Intraoral scanning system for determining infrared signals

Abstract

The present disclosure relates to an intraoral scanning system configured to determine 3D data of a dental subject in an oral cavity. The intraoral scanning system may include an intraoral scanner including: a projector unit configured to emit visible light and infrared light during a scan sequence; an image sensor unit configured to acquire a visible light signal and an infrared signal caused by the emitted visible light and the emitted infrared light, respectively, from at least the dental subject; and one or more processors configured to: control a power of the projector unit such that a first power level of the infrared light emitted during a first time period of the scan sequence is lower than a second power level of the infrared light emitted during a second time period of the scan sequence; and determining 3D data based on the visible light signals acquired during the first time period, and determining an interior region of the dental subject based on the infrared signals acquired during the second time period.

Description

TECHNICAL FIELD

[0001] The present disclosure relates to an intraoral scanning system. More particularly, the present disclosure relates to one or more processors of a system configured to acquire infrared images by varying a power level of emitted infrared light. BACKGROUND

[0002] Many dental and orthodontic procedures can benefit from an accurate three- dimensional (3D) description of a patient's dentition and intraoral anatomy. In particular, it would be helpful to provide a three-dimensional description of both the surface and internal structure of a tooth including the enamel and dentin, as well as a description of the general internal composition of caries and tooth volume. While a pure surface representation of the 3D surface of a tooth has proven very useful in the design and manufacture of dental restorations (e.g., crowns or bridges), the ability to image the internal structure including caries and development of cracks in the enamel and underlying dentin, in particular in combination with surface topography mapping, would be very useful.

[0003] Ionizing radiation (e.g., X-rays) of the prior art has been used to image teeth for diagnostic purposes. For example, X-ray bite-wing radiographs are commonly used to provide non-quantitative images of the internal structure of teeth. However, in addition to the risks of ionizing radiation, such images are generally limited in their ability to show early changes in tooth mineralization (e.g., early caries), resulting in underestimation of the depth of demineralization; they cannot assess the presence or absence of a small carious cavity; they result in frequent overlap of adjacent tooth surfaces, which requires repeated acquisition of radiographs and, thereby, can involve a lengthy and expensive process.

[0004] Some intraoral features, such as soft tissue and plaque, are generally not visualized via X-rays due to their low density. Other techniques, such as cone beam computed tomography (CBCT) can provide tomographic images and can be used to collect more information about the tissue and internal structure, but still require ionizing radiation.

[0005] Furthermore, it is known that near-infrared (NIR) light can be used to assess the internal structure of a tooth and tooth surface in the form of transillumination of the tooth or light reflection and backscattering from the tooth. The NIR range provides a non-ionizing and safe approach to assess caries, restorations, cracks, enamel and dentin defects.

[0006] Further, it is known to cycle between different light sources in a handheld intraoral scanner, such light sources being configured to emit light pulses of different wavelengths, such as visible and non-visible wavelengths. The cycling between different light sources can be provided by switching on and off the different light sources, or by applying mechanical filters in front of the different light sources providing an equivalent on and off switching of the different light sources by blocking the unwanted emitted wavelengths. The mechanical filters can be filter wheels with different blocking filters. A drawback of the known solution is that the emitted light pulses of different wavelengths cannot be detected simultaneously, which is not ideal in the real-time scanning scenario of a handheld intraoral scanner. In this example, it is not possible to achieve real-time determination of e.g. surface information, i.e. reflected visible wavelengths, and internal region information, i.e. reflected non-visible wavelengths, of the same region of the dental object if the user is not forced to move the handheld intraoral scanner slower than he / she is used to use known handheld intraoral scanners. Furthermore, for this example, a slower movement of the handheld intraoral scanner is needed if the best image quality of both surface information and internal region information is wanted to generate a three-dimensional model of the scanned dental object containing both surface and internal region information. In addition, the on-off switching generates unwanted transients on the emitted light pulses, and additionally, the on-off switching causes timing problems between the light sources. The example of implicit mechanical filtering would result in a bulky solution, which would result in a larger handheld intraoral scanner, eventually resulting in an uncomfortable scanner experience for the patient. SUMMARY

[0007] An aspect of the present disclosure is to overcome the above-mentioned drawbacks.

[0008] According to these aspects, an intraoral scanning system is disclosed. The intraoral scanning system can be configured to determine 3D data of a dental object in an oral cavity. The intraoral scanning system can include a handheld intraoral scanner comprising a projector unit configured to emit visible light and infrared light during a scanning sequence. The system can include an image sensor unit configured to acquire, from at least the dental object, a visible light signal and an infrared signal resulting from the emitted visible light and the emitted infrared light, respectively. The image sensor unit can be a high-speed camera with a frame rate higher than 60 frames per second. The image sensor unit can be a very high-speed camera with a frame rate above 500 frames per second. The system can include one or more processors configured to control a power level of the emitted infrared light to a first power level during a first time period of the scanning sequence, and during a second time period, the power level of the emitted infrared light is switched between the first power level and a second power level, and wherein the first power level is lower than the second power level. The one or more processors are further configured to determine the 3D data based on the visible light signal acquired during the first time period, and determine an internal region of the dental object based on the infrared signal acquired during the second time period.

[0009] One or more of the plurality of single-color channels can be configured to transmit infrared light and block visible light.

[0010] The power of the projector unit controlled by the one or more processors can be a supply power to the projector unit.

[0011] The emitted visible light can include wavelengths between 350 nm and 750 nm. The emitted infrared light can include wavelengths between 800 nm and 1200 nm.

[0012] The image sensor unit can include a plurality of cameras, such as high-speed cameras. In one example, the plurality of cameras can be arranged around or beside the projector unit.

[0013] An advantage of the system is that switching between visible light and infrared light is avoided, so that real-time determination of the infrared signal and the 3D data can be obtained without the user having to slow down the movement of the handheld intraoral scanner during scanning of the patient's dentition with both visible light and infrared light.

[0014] An internal region of the dental object can be determined by the one or more processors based on the infrared signal. The internal region can contain information about a dental feature disposed within the dental object. The dental feature can be one or more of an anatomical feature, a disease feature, and a mechanical feature. The anatomical feature can be enamel, dentin, or pulp. The disease feature can be plaque, a crack, or a cavity. The mechanical feature can be a filling and / or a composite restoration.

[0015] The power difference between the first power level and the second power level can be determined by a power ratio. The power ratio can be between 1 / 4 to 1 / 2, 1 / 8 to 1 / 2, 1 / 10 to 1 / 2, 1 / 20 to 1 / 2, or 1 / 10 to 1 / 4.

[0016] The one or more processors are configured to raise and lower the power level of the infrared light during a power ramp between the first power level and the second power level. The power ramp has a slope determined such that no transients will appear on the emitted infrared light.

[0017] The projector unit can contain a plurality of light sources configured to emit one or more color lights and infrared light. The plurality of light sources can be disposed within a single module containing a plurality of light emitting diodes (LEDs) configured to emit different wavelengths within the visible and non-visible wavelength ranges. In another case, the light source (i.e., one or more LEDs) configured to emit infrared light can be disposed separately from the light source configured to emit visible light.

[0018] During the first time period, the one or more processors can be configured to determine sub-internal region information based on the infrared signal and augment the 3D data by a combination of the visible light signal and the sub-internal region information. In this example, the sub-internal region information is subtracted from the visible light signal and the result will be the augmented 3D data where the noise that can have been created in the 3D data due to the infrared light emitted during the first time period will be removed.

[0019] During the second time period, the one or more processors can be configured to determine internal region information based on the infrared signal and determine a composite image based on the infrared signal and the visible light signal, and wherein the composite image contains augmented internal region information. In this example, the composite image can contain the visible light signal subtracted from the infrared signal.

[0020] The first power level of the infrared light emitted during the first time period can be lower than a noise floor level of the image sensor unit. By not turning off the infrared light but instead turning down the power of the emitted infrared light to a first power level that is just below the noise floor level, the quality of the 3D data will not be affected by the emitted infrared light during the first time period. Furthermore, since the infrared light is not turned off, no unwanted transients will appear on the emitted light pulses.

[0021] The one or more processors can be configured to control the projector unit during a scan sequence, and during a first time period, the emitted visible light includes a first visible light turned on at a constant power level, while the infrared light is constantly turned on at a first power level. During a second time period, the emitted visible light includes a second visible light turned on and off at a second pulse repetition rate, and the first visible light is turned on and off at a first pulse repetition rate that is asynchronous to the on / off switching of the second visible light, and wherein the power level of the infrared light is turned up when the first and second visible lights are turned off, and the infrared light is turned down when the first or second visible light is turned on, and wherein the power level of the infrared light is turned up and down between the first power level and a second power level.

[0022] The first and second time periods repeat throughout the scan sequence, and wherein the second time period can repeat within 100 ms, within 200 ms, or within 500 ms.

[0023] The second time period can be between 30 ms and 50 ms, between 30 ms and 40 ms, approximately 30 ms, or approximately 40 ms, or approximately 50 ms.

[0024] The first visible light can include wavelengths corresponding to white light, and wherein the second visible light includes wavelengths corresponding to blue light. In this example, the emitted blue light is excitation fluorescence information from the dental object, and the fluorescence information can include green fluorescence information and red fluorescence information.

[0025] The projector unit can be configured to emit visible light including white light and blue light during a scan sequence, wherein a first pulse repetition rate of the white light is different from a second pulse repetition rate of the blue light, and wherein the infrared light is constantly turned on at a power level during a first time period, and constantly turned on between two power levels during a second time period.

[0026] The one or more processors can be configured to adjust the first and second pulse repetition rates based on a scan mode of the handheld intraoral scanner. For example, in a scan mode where the projector unit emits both visible light and infrared light, the pulse repetition rate of the visible light is increased, with the infrared light constantly turned on during the scan sequence.

[0027] The first pulse repetition rate is faster than the second pulse repetition rate, and in this example, the higher pulse repetition rate is necessary to provide 3D data with a quality required to determine a 3D model.

[0028] The one or more processors can be configured to change the first pulse repetition rate and / or the second pulse repetition rate during the second time period based on the scan pattern. For example, the low second pulse repetition rate can result in acquiring the infrared signal each time the second visible light is turned off during the second timer period. In another example, the intraoral scanning system includes a filter unit configured to output a filtered visible light signal and a combined filtered light signal, where the combined filtered light signal includes the infrared signal and the first color, and where the filtered visible light signal includes at least the first color. The one or more processors can then be configured to determine the infrared signal by subtracting the first color of the filtered visible light signal from the combined filtered light signal. Then, when the second pulse repetition rate is doubled relative to the low second pulse repetition rate, the one or more processors can then be configured to simultaneously acquire the second visible light signal and the infrared signal due to the filter unit.

[0029] When the second pulse repetition is set to the low second pulse repetition rate, the one or more processors are configured to acquire the second visible light signal and the infrared signal at different time periods in the scan sequence. Then, when the second pulse repetition rate is doubled relative to the low second pulse repetition rate, it will not be possible to acquire the second visible light signal and the infrared signal at different time periods due to the width / size of the second time period. In this example, due to the filter unit, the filter unit allows the one or more processors to simultaneously acquire the second visible light signal and the infrared signal.

[0030] The intraoral scanner can include a filter unit configured to receive a visible light signal and an infrared signal from at least the dental object, and where the filter unit can be configured to transmit a filtered visible light signal and a combined filtered light signal, where the combined filtered light signal includes a combination of a first color light of the visible light signal and an infrared light of the infrared signal. The filter unit can include a plurality of single color channels configured to output the filtered visible light signal, and a plurality of combined color channels configured to output the combined filtered light signal. The image sensor unit can be configured to acquire the filtered visible light signal and the combined filtered light signal. Further, the one or more processors can be configured to determine the infrared signal based on a subtraction of one or more color lights of the combined filtered light signal from the filtered visible light signal, and determine 3D data of the dental object based on at least the filtered visible light signal.

[0031] The one or more processors can be configured to determine fluorescence information of the dental object from the visible light signal. In this example, the fluorescence information is excited by the visible light including an emission of a blue wavelength between 350 nm and 500 nm.

[0032] The internal region can be determined from a composite scan information comprising a difference between the infrared signal and the visible light signal.

[0033] The fluorescence information can comprise green fluorescence information and / or red fluorescence information, wherein the one or more processors can be configured to determine a first difference between the infrared signal and the green fluorescence information and a second difference between the infrared signal and the red fluorescence information, and wherein the composite scan information comprises a sum of the first difference and the second difference. In this example, the contrast between dental features within the internal region of the dental object is significantly improved.

[0034] The composite scan information can comprise a sum of the infrared signal, the green fluorescence information and the red fluorescence information. In another example, the composite scan information can comprise subtracting the infrared signal from the visible light signal comprising white or green wavelengths.

[0035] The one or more processors can be configured to determine the 3D data based on one or more colors of the visible light signal, such as white, red and / or green wavelengths.

[0036] The scan sequence can be a full scan of at least the upper jaw and / or the lower jaw of the oral cavity.

[0037] The emitted visible light can comprise visible light pulses, and the emitted infrared light can not be pulsed.

[0038] The filter unit can comprise a pixel pattern filter comprising a plurality of monochrome channels and an infrared filter configured to block or partially block the infrared light signal of a first group of the plurality of monochrome channels. The infrared filter can be further configured to transmit the infrared light signal of a second group of the plurality of monochrome channels, and wherein the second group of the plurality of monochrome channels corresponds to the plurality of combined filter channels.

[0039] The filter unit can be constructed in a manner allowing alignment and arrangement in front of the image sensor unit, and this ultimately results in a compact filter unit. The pixel pattern filter can comprise a first pixel pattern surface and a second pixel pattern surface opposite the first pixel pattern surface. The infrared filter can be arranged on or near the first pixel pattern surface, and the image sensor can be arranged on or near the second pixel pattern surface. In another example, the infrared filter can comprise a first infrared surface and a second infrared surface opposite the first infrared surface, and wherein the pixel pattern filter is arranged on or near the first infrared surface, and the image sensor unit can be arranged on or near the second infrared surface.

[0040] The pixel pattern filter can be a Bayer filter.

[0041] 3D data includes 3D geometry data of the dental object and / or color data of the dental object. The 3D data can include a plurality of sub-scans acquired by the handheld intraoral scanner and the plurality of sub-scans are stitched together to form the 3D data. The 3D geometry data can include 3D shapes of teeth and gums and the color data includes colors of the teeth and gums. Further, the 3D data can include shade values of the teeth.

[0042] To improve real-time display of the 3D data and internal regions of the dental object in 2D or 3D, the one or more processors can be configured to determine the 3D data and internal regions of the dental object in parallel based on the infrared signal and / or a combination of the infrared signal and the visible light signal, and / or a combination of the infrared signal, the visible light signal that is white, and fluorescent green and fluorescent red. The one or more processors can be configured to receive the infrared signal and the filtered visible light signal from the image sensor unit sequentially and process the received signals in parallel, but with a slight delay between the start of processing of the two signals caused by the sequential receipt of the infrared signal and the filtered visible light signal. In another example, the image sensor unit is configured to output the filtered visible light signal in parallel with the combined filtered light signal, such that no delay occurs between the processing of the two signals.

[0043] In some cases, the filtered visible light signal used to determine the 3D data can include a sum of red, green, and blue wavelengths, and the first color light combined with the reflected infrared light in the combined filtered light signal can be green. In this example, the one or more processors are configured to determine a virtual visible light signal from each of the combined filtered light signals, where the virtual visible light signal includes green wavelengths. The virtual visible light signal is determined by interpolating between the filtered visible light signals of adjacent single color channels related to each of the combined color channels, and where the filtered visible light signals of the adjacent single color channels include green wavelengths. The virtual visible light signal corresponds to the first color light.

[0044] The first color light of the combined filtered light signal can be determined by interpolating between a first set of the plurality of single color channels.

[0045] The one or more processors can then be configured to combine the virtual visible light signal of each of the combined filtered light signals with the filtered visible light signal to determine the 3D data. In this example, all pixels aligned with the plurality of single color channels and the plurality of combined color channels are used to determine the 3D data. Thus, there is no loss of resolution in obtaining the 3D data compared to examples where the one or more processors discard the plurality of combined filtered light signals to determine the 3D data.

[0046] The one or more processors can be configured to vary a pulse repetition rate of the visible light emitted from the projector unit based on a wavelength of the emitted visible light. The one or more processors can be configured to increase the pulse repetition rate of the visible light emitted from the projector unit to improve a signal-to-noise ratio of the filtered visible light signal. For example, where the emitted light of the projector unit contains wavelengths between 350 nm and 500 nm, the one or more processors are configured to increase the pulse repetition rate of the emitted visible light. Since the infrared light is constantly on throughout the scan sequence of the patient, then there is no pulse repetition rate defined for the emitted infrared light.

[0047] The pulse duration of the emitted visible light pulses can be around 0.4 ms. In a scan mode where only white and blue visible light pulses are switched between, the switching period between the two colors can be around 0.8 ms, corresponding to a pulse repetition rate (PRR) of 1.25 kHz. This would be the PRR of the white visible light pulses. In another scan mode, the PPR of the blue visible light pulses occurs only once every four pulses, and then the PPR of the blue pulses is reduced to 625 Hz.

[0048] The one or more processors can be configured to vary a gain level of the image sensor unit based on a wavelength and / or power level of the light emitted from the projector unit. To further improve the signal-to-noise ratio of the filtered visible light signal, the one or more processors are configured to increase the gain level of the light emitted from the projector unit.

[0049] Throughout the scan of the patient, the projector unit can be configured to constantly emit infrared light while emitting visible light. In this example, switching of the emitted infrared light is avoided, thereby avoiding unwanted transients on the emitted infrared light.

[0050] The determination of the infrared signal is performed by the one or more processors. In this example, the one or more processors can be configured to generate a color light magnitude signal from the filtered visible light signal, and wherein the color light magnitude signal can be one or more of a red light, a green light, and a blue light. If the red, green, and blue colors are combined, then the color light magnitude signal corresponds to a white light. The one or more processors can then be configured to generate a combined light magnitude signal from the combined filtered signal of the combined filtered signals, wherein the combined light magnitude signal can be a sum of the infrared light and a first color containing one or more colors of the color light magnitude signal. The one or more processors can then be configured to determine the infrared signal by subtracting the color light magnitude signal from the combined light magnitude signal.

[0051] The color light amplitude signal can be a sum of red, green and blue light, and wherein the combined light amplitude signal is a sum of infrared and red, green and blue light. In another example, the color light amplitude signal comprises green light, and wherein the combined light amplitude signal is a sum of infrared and green light.

[0052] The color light amplitude can be generated based on filtered visible light signals from a first group of multiple monochrome channels, and the combined light amplitude signal can be generated based on a single combined color channel of multiple combined color channels, and wherein the first group of multiple monochrome channels is arranged in proximity to the single combined color channel. By arranging this first group in proximity to the single combined color channel, an improved approximation of the color of the color light amplitude and the first color light of the combined light amplitude will result. To improve the approximation of the color of the color light amplitude, the first group can be arranged as neighboring channels to the single combined color channel. The first group of monochrome channels constitutes a color filter channel neighborhood, and the color filter channel neighborhood is one of a 4-neighborhood color filter channel arrangement, a diagonal-neighborhood color filter channel arrangement or an 8-neighborhood color filter channel arrangement.

[0053] A 2D infrared image or a synthetic scan image can be determined based on the infrared signal, and to obtain a best resolution quality of the 2D infrared image, a ratio between the multiple combined color channels and the multiple monochrome channels is determined to be between 1 / 16 and 1 / 4.

[0054] A handheld intraoral scanner can be configured to scan a patient during a scan sequence, and during the scan sequence, the projector unit can be configured to emit visible light and infrared light such that a 3D model is determined and displayed in real-time based on the 3D data. Further, an infrared signal can also be determined in real-time. In one example, the one or more processors can be configured to determine and display a 2D or 3D infrared image based on the infrared signal, or determine and display a composite scan image based on the infrared signal. In yet another example, the one or more processors are configured to determine in real-time a 3D model that contains one or more of the following information of a dental object or dentition: 3D geometry, color information, hue information, and internal region information determined from at least the infrared signal. The one or more processors can be configured to control the projector unit during the scan sequence, and wherein the scan sequence contains at least a first time period and a second time period, wherein during the first time period, the emitted visible light contains a first visible light turned on at a constant power level, while the infrared light is turned on at a constant power level, and during the second time period, the emitted visible light contains a second visible light turned on and off at a second pulse repetition rate, and the first visible light is turned on and off asynchronously to the on / off switching of the second visible light at a first pulse repetition rate, and wherein the power level of the infrared light is increased when the first visible light and the second visible light are turned off and decreased when the first visible light or the second visible light is turned on, and wherein the power level of the infrared light is increased and decreased between a first power level and a second power level.

[0055] The first visible light can contain a white wavelength, a green wavelength, or a red wavelength, and the second visible light can contain a blue wavelength for the purpose of exciting susceptible molecules on the dental object to excite red and green fluorescence signals. The one or more processors can be configured to determine a composite scan image based on the infrared light, the first visible light, and / or the second visible light.

[0056] The one or more processors can be configured to change a signal-to-noise ratio of the filtered visible light signal by changing a pulse repetition rate during a time period of the emitted visible light. During the scan sequence, the one or more processors can be configured to change the signal-to-noise ratio of the filtered visible light signal by changing the first pulse repetition rate during the second time period based on the scan pattern. For example, in a scan pattern in which the projector unit emits both visible light and infrared light, the pulse repetition rate of the visible light is increased relative to the scan sequence, with the infrared light being constantly turned on during the scan sequence.

[0057] The scan sequence can include repetitions of a first time period and a second time period, and wherein the first time period and the second time period are repeated throughout the scan sequence, and wherein the second time period is repeated within 100 ms, 200 ms, or 500 ms. The first time period can be longer than the second time period. The first time period can be between 100 ms and 500 ms, or between 100 ms and 250 ms. The second time period can be between 30 ms and 50 ms, between 30 ms and 40 ms, about 30 ms, or about 40 ms, or about 50 ms. With this time period, the scan sequence will provide one or more processors with a sufficient amount of visible light signals and infrared signals to determine 3D data and infrared signals that will inevitably result in a 3D model of necessary quality for a user to investigate dental plaque, caries, cracks, and other dental features within and on dental objects in the dentition.

[0058] The scan sequence can be a full scan of at least the upper jaw and / or the lower jaw of the patient’s oral cavity.

[0059] In another example, the projector unit can be configured to emit a first visible light containing white light and a second visible light containing blue light during the scan sequence, and wherein a first pulse repetition rate of the first visible light is different from a second pulse repetition rate of the second visible light, and wherein infrared light is constantly emitted during the scan sequence. The one or more processors can be configured to adjust the first repetition rate and the second repetition rate based on a scan mode of the handheld intraoral scanner. The first pulse repetition rate can be faster than the second pulse repetition rate. Based on the emitted blue light, the one or more processors can be configured to determine fluorescence information of the dental object from the filtered visible light signals. The filtered visible light signals can contain excited fluorescent red light and fluorescent green light excited by the emitted blue light.

[0060] The one or more processors can be configured to determine 3D data based on two or more different colors of the filtered visible light signals. For example, the 3D data can be determined based on white light that can contain a sum of red light, blue light, and green light, or the 3D data can be determined based on blue light, green light, or red light, or a combination of blue light, green light, and red light.

[0061] The power level of the infrared light can be constant throughout the scan sequence of at least the upper jaw and / or the lower jaw of the oral cavity.

[0062] To improve the power consumption of the handheld intraoral scanner, the power level of the infrared light can be set to a first power level during a primary time period and to a second power level during a secondary time period, wherein the first power level is lower than the second power level. The primary time period can correspond to a first time period of the scan sequence, which mainly means the capturing of the visible light signals for determining the 3D data. The secondary time period corresponds to a second time period of the scan sequence, which mainly means the capturing of the scattered visible light and scattered infrared light for determining the fluorescence information.

[0063] The first power level can be between 50% and 90%, between 10% and 50% or between 5% and 40% of the second power level.

[0064] The first power level can provide a signal above the noise floor level of the image sensor unit.

[0065] The emitted visible light can comprise visible light pulses, and wherein the emitted infrared light is not pulsed, as the emitted infrared light is constantly on throughout the entire scan sequence of the patient’s jaw.

[0066] The one or more processors can be configured to determine an infrared signal based on a subtraction of one or more color lights of the combined filtered light signal and the filtered visible light signal, and the inner region is determined by a composite scan information comprising a difference between the infrared signal and one or more color lights of the filtered visible light signal. The composite scan information comprises an enhanced contrast between the dental features, wherein the enhanced dental features can be depicted on or in a 3D model determined from the 3D data and the composite scan information.

[0067] The one or more processors can be configured to determine a first difference between the infrared signal and the green fluorescence information and a second difference between the infrared signal and the red fluorescence information, and wherein the composite scan information comprises a sum of the first difference and / or the second difference. In this example, the contrast between the dental features will be even more enhanced.

[0068] The composite scan information can comprise a sum of the infrared signal, the green fluorescence information and the red fluorescence information, and in this example the dentin-enamel junction is further enhanced, making it easier to distinguish from other dental features of the dental object.

[0069] The composite scan information provides an enhanced visualization of caries of the tooth in such a way that it becomes easier for the dentist to identify and treat the caries.

[0070] The intraoral scanning system can be configured to enhance the visualization of the dental restoration in such a way that it becomes easier for the dentist to identify and treat the secondary caries, and to identify the type of the restoration, such as the type of filling, inlay, onlay, crown and / or sealant.

[0071] Intraoral scanning systems can be configured to enhance the visibility of the dentin-enamel junction (DEJ) of teeth in such a way that it becomes easier for dentists to identify the DEJ for clinical assessment.

[0072] Intraoral scanning systems can be configured to generate or update three-dimensional 3D models while using different wavelength modes to determine synthetic scanning information.

[0073] In addition to enhancing visualization of caries, restorations, and the dentin-enamel junction, another aspect of this disclosure is the detection of early caries at a stage where preventative measures may affect remineralization, allowing for the repair of damage caused by carious infection before more complex restorative procedures are required. Advantageously, this disclosure is more accurate in detecting caries at the early stages of infection compared to methods using existing fluorescent or near-infrared approaches.

[0074] Intraoral scanning systems can be configured to provide synthetic scan data based on captured visible light and determined infrared signals. The infrared signals may primarily consist of reflections from the interior of the tooth (i.e., the internal region of the dental object), with significantly less reflection from the tooth's surface. The visible light signals may primarily consist of reflections from the tooth's surface, with significantly less reflection from the interior of the tooth (i.e., the internal region of the dental object). The infrared signals may contain information about the dental condition from within the tooth, not just from the surface.

[0075] The synthetic scan information does not involve the superposition of two 2D images, each of which is associated with a different emission wavelength from the projector unit. In this example, no enhancement of internal structural information is provided. The synthetic scan information can be a combination of the intensity levels of each pixel of 2D images associated with different wavelengths. For example, in a first time period, the image sensor unit captures light information associated with a visible wavelength, and in a second time period, the image sensor unit captures light information associated with an infrared wavelength, and the intensity levels of the two time periods are recorded and combined to enhance dental conditions, i.e., dental features such as dentin, enamel, dentin-enamel junction, plaque, caries, cracks, etc. The combination of intensity levels can be done digitally by subtracting and / or adding the intensity levels. In another example, for at least three different wavelengths such as white wavelength, blue wavelength, and infrared wavelength, intensity levels can be captured and recorded during at least three time periods.

[0076] Infrared wavelengths can be between 750 nm and 1500 nm.

[0077] The one or more processors can be configured to display synthetic scan information and 3D models on the system's display unit.

[0078] The one or more processors can be configured to generate or update the 3D model and determine the synthetic scan information with the filtered visible light signal, the synthetic scan information containing enhanced internal structure in the form of enhanced contrast between dental features such as caries lesions and the tooth structure. The surface of the dental object is mainly provided by the visible light information and the internal regions of the dental object are mainly provided by the synthetic scan information or the infrared signal determined by the one or more processors.

[0079] In another example, the handheld intraoral scanning device first performs a scan for generating or updating the 3D model and then later performs another scan for determining the synthetic scan information, which compared to the present disclosure will result in a more complicated way of aligning the location of the synthetic scan information on the 3D model.

[0080] The intraoral scanning system can comprise an intraoral scanner comprising a projector unit and an image sensor unit. The system can comprise one or more processors configured to control the power level of the emitted visible light to a first power level during a first time period of a scanning sequence and during a second time period the power level of the emitted visible light is switched between the first power level and a second power level, and wherein the first power level is lower than the second power level, and wherein the emitted infrared light is modulated at a given frequency. The modulation of the emitted infrared light can be based on a switching of a switch. The advantage of having a white light with constant on is that the temperature of the white light source is more constant and closer to the idle temperature of the white light source. Furthermore, the images generated based on the acquired infrared signal will have more sub-surface scattering from the dental object. This will result in easier to see the infrared image or the synthetic scan image of the tooth. Fortunately, it turns out that dentists prefer this.

[0081] Adding white light to the infrared image or the synthetic scan image can be done digitally, however, the above described solution is done in a similar way, which means that the computation of the one or more processors uses less.

[0082] The first power level can be between 0.5% and 10%, 1% and 5%, or preferably around 1%. The advantage of emitting visible light, e.g. white light, at the first power level at the same time as the ultraviolet light or the infrared light is emitted is that the synthetic scan information will contain additional sub-surface reflections caused by the emitted visible light. And, the additional sub-surface reflections will even further enhance the contrast of interproximal lesions or the enamel junction in the dental object. BRIEF DESCRIPTION OF DRAWINGS

[0083] The various aspects of the disclosure can best be understood with reference to the following detailed description taken in conjunction with the accompanying drawings. The drawings are schematic and simplified for clarity and they merely provide the basic understanding of the structure and function of the application. They are not to be considered restrictive of the application's scope as it can occur in other variations and modifications, which are equally clear to those having ordinary skill in the art. Throughout the drawings, like reference numerals are used for like elements or components. The various features of the aspects can each be combined with any or all of the other aspects. These and other aspects, features, and / or technical effects are readily apparent to one skilled in the art from the following detailed description, the accompanying drawings, and the appended claims. Figure 1A , Figure 1B , Figure 1C and Figure 1D different examples of intraoral scanning systems are illustrated; Figure 2A , Figure 2B and Figure 2C different examples of filter units are illustrated; Figure 3A , Figure 3B , Figure 3C and Figure 3D different examples regarding synthesizing scan information are illustrated; and Figure 4 another example of an intraoral scanning system is illustrated. DETAILED DESCRIPTION

[0084] The detailed description set forth below, in connection with the appended drawings, is intended as a description of various configurations and is not intended to limit the scope of the disclosure. The detailed description includes specific details for the purpose of providing a thorough understanding of various concepts. However, it will be apparent to those skilled in the art that these concepts can be practiced without these specific details. Numerous aspects of devices, systems, media, programs, and methods are described by various blocks, functional units, modules, components, circuits, steps, processes, algorithms, etc. (collectively referred to as “elements”). These elements can be realized using electronic hardware, computer programs, or any combination thereof, depending on the particular application or

[0085] Electronic hardware can include microprocessors, microcontrollers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), programmable logic devices (PLDs), gated logic, discrete hardware circuits, and other suitable hardware configured to perform the various functionality described throughout this disclosure. Computer programs, whether referred to as software, firmware, middleware, microcode, hardware description language, or otherwise, should be interpreted broadly to encompass a set of instructions that are executable by a computer or a computer processor, including any changes to memory layouts, instruction mapping, instruction sets, etc. In general, a computer program can include a handful of

[0086] Scans for providing intraoral scan data can be performed by a dental scanning system that can comprise an intraoral scanning device such as a TRIOS series scanner from 3Shape A / S. The dental scanning system can comprise wireless capabilities provided by a wireless network unit. The scanning device can employ a scanning principle such as a triangulation-based scanning, a confocal scanning, a focus scanning, an ultrasound scanning, an x-ray scanning, a stereo vision, a structure from motion, an optical coherence tomography OCT, or any other scanning principle. In an embodiment, the scanning device is capable of obtaining surface information by projecting a pattern and translating a focal plane along an optical axis of the scanning device and capturing a plurality of 2D images at different focal plane positions such that each series of captured 2D images corresponding to each focal plane forms a stack of 2D images. The acquired 2D images are also referred to herein as raw 2D images, where raw in the present context means that the images are not subjected to image processing. The focal plane positions are preferably moved along the optical axis of the scanning system such that for a given view of the object, i.e. for a given arrangement of the scanning system relative to the object, the 2D images captured at a plurality of focal plane positions along the optical axis form a stack of 2D images (also referred to herein as a sub-scan). After moving the scanning device relative to the object or imaging the object at different views, a new stack of 2D images for this view can be captured. The focal plane positions can be changed by at least one focusing element, e.g. a moving focusing lens. During a scanning session, the scanning device is generally moved relative to the dentition and angled such that at least some groups of sub-scans at least partially overlap in order to enable reconstruction of a digital dental 3D model by stitching the overlapping sub-scans together in real time and displaying a progress of the virtual 3D model on a display as feedback to the user. The result of the stitching is a digital 3D representation of the surface that is larger than the surface that can be captured by a single sub-scan, i.e. larger than the field of view of the 3D scanning device. The stitching, also referred to as registration and fusion, works by identifying overlapping regions of the 3D surface in the various sub-scans and transforming the sub-scans to a common coordinate system such that the overlapping regions match, ultimately resulting in a digital 3D model. An iterative closest point (ICP) algorithm can be used for this purpose. Another example of a scanning device is a triangulation scanner, where a time-varying pattern is projected onto the dental arch and a sequence of images of different pattern configurations is acquired by one or more cameras positioned at an angle relative to the projector unit.

[0087] Color texture of the dental arch can be obtained by illuminating the object with different monochromatic colors such as separate red, green and blue colors or by illuminating the object with polychromatic light such as white light. The 2D images can be acquired during a flash of white light.

[0088] In general, the process of obtaining surface information of a dental arch to be scanned in real time requires the scanning device to illuminate the surface and obtain a large number of 2D images. Typically, a high-speed camera with a frame rate of 300-2000 2D frames per second is used depending on the technology and 2D image resolution. The scanning device needs to process the large amount of image data either to forward the raw image data stream directly to an external processing device or to perform some image processing before transferring the data to an external device or display. This process requires a number of electronic components inside the scanner to operate with high workload, thereby requiring high current demand.

[0089] The scanning device comprises one or more light projectors configured to generate an illumination pattern to be projected onto the three-dimensional dental arch during a scanning session. The light projector(s) preferably comprise a light source, a mask with a spatial pattern, and one or more lenses, such as a collimating lens or a projection lens. The light source can be configured to generate light of a single wavelength or a combination of wavelengths (monochromatic or polychromatic). The combination of wavelengths can be produced by using a light source configured to produce light comprising different wavelengths, such as white light. Alternatively, the light projector(s) can comprise a plurality of light sources, such as LEDs, that individually produce different wavelengths of light that can be combined to form light comprising different wavelengths, such as red, green, and blue. Thereby, the light produced by the light source can be defined by a wavelength defining a specific color, or by a range of different wavelengths defining a combination of colors, such as white light. In an embodiment, the scanning device comprises a light source configured for exciting fluorescent materials of the teeth to obtain fluorescence data from the dental arch. Such a light source can be configured to produce a narrow range of wavelengths. In another embodiment, the light from the light source is infrared (IR) light that is able to penetrate dental tissue. The light projector(s) can be a DLP projector using a micro-mirror array for generating a time-varying pattern, or a diffractive optical element (DOF), or a backlit mask projector, wherein the light source is placed behind a mask with a spatial pattern, so that the light projected onto the surface of the dental arch is patterned. The backlit mask projector can comprise a collimating lens for collimating the light from the light source, placed between the light source and the mask. The mask can have a checkerboard pattern, so that the generated illumination pattern is a checkerboard pattern. Alternatively, the mask can feature other patterns, such as lines or dots.

[0090] The scanning device preferably further comprises optical components for guiding the light from the light source to the surface of the dental arch. The specific arrangement of the optical components depends on whether the scanning device is a focus scanning apparatus, a scanning device using triangulation, or any other type of scanning device. The same applicant further describes a focus scanning apparatus in EP 2 442 720 B1, the entire content of which is incorporated herein.

[0091] Using optical components of the scanning device, light reflected from the dental arch in response to the illumination of the dental arch is directed toward the image sensor(s). The image sensor(s) are configured to generate a plurality of images based on the incident light received from the illuminated dental arch. The image sensor unit can be a high-speed image sensor, such as an image sensor configured to acquire images with an exposure of less than 1 / 1000 of a second or a frame rate of more than 250 frames per second (fps). As an example, the image sensor can be a rolling shutter (CCD) or a global shutter sensor (CMOS). The image sensor(s) can be a monochrome sensor containing a color filter array such as a Bayer filter and / or a further filter that can be configured to substantially remove one or more color components from the reflected light before the reflected light is converted into an electrical signal and only retain the other, non-removed components. For example, such a further filter can be used to remove a certain portion of the white light spectrum, such as the blue component, and only retain the red and green components from the signal generated in response to the excited fluorescent material of the teeth.

[0092] The network unit can be configured to connect the dental scanning system to a network comprising a plurality of network elements including at least one network element configured to receive the processed data. The network unit can comprise a wireless network unit or a wired network unit. The wireless network unit is configured to wirelessly connect the dental scanning system to a network comprising a plurality of network elements including at least one network element configured to receive the processed data. The wired network unit is configured to establish a wired connection between the dental scanning system and a network comprising a plurality of network elements including at least one network element configured to receive the processed data.

[0093] The dental scanning system preferably further comprises a processor configured to generate scanning data (such as extra-oral scanning data and / or intra-oral scanning data) by processing two-dimensional (2D) images acquired by the scanning device. The processor can be part of the scanning device. As an example, the processor can comprise a field-programmable gate array (FPGA) and / or an advanced RISC machine (ARM) processor located on the scanning device. The scanning data comprises information related to a three-dimensional dental arch. The scanning data can comprise any of the following: 2D images, 3D point clouds, depth data, texture data, intensity data, color data, and / or combinations thereof. As an example, the scanning data can comprise one or more point clouds, wherein each point cloud comprises a set of 3D points describing a three-dimensional dental arch. As another example, the scanning data can comprise images, each image comprising image data described by, for example, image coordinates and a timestamp (x, y, t), wherein depth information can be inferred from the timestamp. The image sensor(s) of the scanning device can acquire a plurality of raw 2D images of the dental arch in response to illuminating the object using one or more light projectors. The plurality of raw 2D images can also be referred to herein as a stack of 2D images. The 2D images can subsequently be provided as input to the processor, which processes the 2D images to generate the scanning data. The processing of the 2D images can comprise a step of determining which part of each of the 2D images is in focus in order to infer / generate depth information from the images. The internal depth information can be used to generate a 3D point cloud comprising a set of 3D points described by, for example, Cartesian coordinates (x, y, z) in space. The 3D point cloud can be generated by the processor or another processing unit. Each 2D / 3D point can also comprise a timestamp indicating when the 2D / 3D point was recorded, i.e., which image from the stack of 2D images the point originates from. The timestamp is related to the z-coordinate of the 3D point, i.e., the z-coordinate can be inferred from the timestamp. Thus, the output of the processor is the scanning data, and the scanning data can comprise image data and / or depth data described by, for example, image coordinates and a timestamp (x, y, t), or alternatively (x, y, z). The scanning device can be configured to transmit other types of data in addition to the scanning data. Examples of data include 3D information, texture information, such as infrared (IR) images, fluorescence images, reflective color images, x-ray images, and / or combinations thereof.

[0094] The examples illustrated in the following figures can be performed by one or more processors.

[0095] Figure 1A , Figure 1B , Figure 1C and Figure 1DExamples of intraoral scanning systems 1 are illustrated. In these examples, the system 1 comprises a handheld intraoral scanner 10 which can be handheld and used to scan a patient’s mouth. The handheld intraoral scanner can comprise a projector unit 3 configured to emit 8 visible light (51A, 51B) and infrared light 52 during a scan sequence 50. The handheld intraoral scanner 10 can comprise an image sensor unit 4 configured to acquire from at least a dental object a visible light signal 9 and an infrared signal 9 resulting from the emitted 8 visible light (51A, 51B) and the emitted infrared light 52, respectively. The system 1 comprises one or more processors 2 configured to control the power of the projector unit 3 such that a first power level 52A of the emitted 8 infrared light 52 during a first time period 56 of the scan sequence 50 is lower than a second power level 52B of the emitted 8 infrared light 52 during a second time period 55 of the scan sequence 50. Further, during the first time period 56, the emitted 8 visible light 51A is constantly on at a constant power level, and during the first time period 56, the emitted visible light comprises a white wavelength, and during the second time period 55, the emitted visible light comprises two modalities (51A, 51B) of a white wavelength 51A and a blue wavelength 51B. During the second time period, the one or more processors 2 are configured to asynchronously turn on and off the two modalities (51A, 51B). When the first and second modalities (51A, 51B) are off, then the power of the infrared light 52 is turned up to the second power level 52B, and when the first or second visible light is on, it is turned down to the first power level 52A. Further, the first time period 56 and the second time period 55 are repeated multiple times during the scan sequence 50. In Figure 1A , the first power level 52A of the emitted 8 infrared light 52 is lower than a noise floor 102 of the image sensor unit 4, and during the second time period 55, the one or more processors 2 are configured to turn up and down the power level of the emitted infrared light 52 between the first power level 52A and the second power level 52B. In other words, the one or more processors 2 are configured to switch between the first power level 52A and the second power level 52B during the second time period 55. For example, the second time period can be repeated within 100 ms, within 200 ms, or within 500 ms, and the second time period can be between 30 ms and 50 ms, between 30 ms and 40 ms, approximately 30 ms, or approximately 40 ms, or approximately 50 ms. In Figure 1A , Figure 1B , and Figure 1C , the one or more processors 2 are further configured to determine 3D data based on the acquired 9 visible light signal during the first time period 56, and to determine an internal region of the dental object based on the acquired infrared signal during the second time period 55.

[0096] Figure 1B Fig. illustrates an example similar to Figure 1A Fig. illustrates an example similar to

[0097] Figure 1C Fig. illustrates an example similar to Figure 1A Fig. illustrates an example similar to

[0098] Figure 1D Fig. illustrates an example where the pulse repetition rate of the visible light 51 in the second time period 55 has increased to such an extent that, in order not to increase the width of the second time period 55, the projector unit 5 has to emit both visible light 51 and infrared light 52 at the same time so that the one or more processors 2 acquire both the visible light signal and the infrared light signal during the second time period 55. In this example, the handheld intraoral scanner 10 comprises a filter unit 3 arranged in front of the image sensor unit 4. The filter unit 3 is configured to transmit a filtered visible light signal and a combined filtered light signal, wherein the combined filtered light signal comprises a combination of a first color light of the visible light signal and infrared light of the infrared light signal. The filter unit can comprise a plurality of single color channels 11 configured to output the filtered visible light signal and a plurality of combined color channels (12A, 12B) configured to output the combined filtered light signal.

[0099] The image sensor unit 4 is configured to acquire a filtered visible light signal by the pixels 14 aligned 16 with one or more of the plurality of single color channels 11 and to acquire a combined filtered light signal by the pixels 15 aligned 16 with one or more of the plurality of combined color channels (12A, 12B). In this example, each of the plurality of single color channels 11 and each of the plurality of combined color channels (12A, 12B) is aligned 16 with each of the pixels (14, 16) of the image sensor unit 4.

[0100] The one or more processors 2 receive the filtered visible light signal and the combined filtered light signal, wherein the one or more processors 2 are configured to determine an infrared signal based on a subtraction of one or more color light of the combined filtered light signal from the acquired filtered visible light signal. The one or more processors 2 are further configured to determine an internal region of the dental object based on the infrared signal. In addition, the one or more processors are configured to determine 3D data of the dental object based on at least the filtered visible light signal. The one or more processors 2 are then configured to determine a 3D model, the 3D model 45 containing one or more of the following information of the dental object or dentition: 3D geometry, color information, hue information, and internal region information determined based on at least the infrared signal. The one or more processors 2 are configured to determine the 3D data and the internal region of the dental object in parallel based on the infrared signal.

[0101] The 3D model and the internal region can be determined in parallel.

[0102] Figure 2A 、 Figure 2B 、 Figure 2C Different examples of the filter unit 5 are illustrated. In Figure 2A the filter unit 5 contains a plurality of combined color channels (12A, 12B), in this particular example, the plurality of combined color channels contains two combined color channels (12A, 12B). In addition, the filter unit 5 contains a plurality of single color channels (11, 11A, 11B). The combined color channels (12A, 12B) are configured to output a combined filtered light signal containing a combination of green light and infrared light, wherein wavelengths within the blue and red spectrum are blocked from being output through the combined color channels (12A, 12B). In this example, the first color light of the combined color channels (12A, 12B) contains green wavelengths. The plurality of single color channels 11 are configured to output a filtered visible light signal containing blue, green, and red light. The one or more processors 2 are configured to determine an infrared signal by subtracting the green light output by the adjacent single color channels (11A, 11B) related to the respective combined color channels (12A, 12B) from the combined filtered visible light signal. In Figure 2BIn this example, the composite color channels (12A, 12B) are configured to output a combined filtered optical signal containing a combination of white and infrared light. One or more processors 2 are then configured to determine the infrared signal by subtracting the green, red, and blue light output from the adjacent monochromatic channels (11A, 11B) associated with the respective composite color channels (12A, 12B) from the combined filtered visible light signal. In this example, the two composite color channels (12A, 12B) share two monochromatic channels (11A+11B). Figure 2A and Figure 2B In the two examples shown, one or more processors 2 are configured to generate color light amplitude signals (11A, 11B) from filtered visible light signals, wherein the color light amplitude signals (11A, 11B) are one or more of red, green, and blue light. Figure 2A In the diagram, the color light amplitude signals (11A, 11B) correspond to green light, and... Figure 2B In this context, the color light amplitude signals (11A, 11B) correspond to the sum of red, green, and blue light. Furthermore, one or more processors are configured to generate a combined light amplitude signal from the combined filtered signals, wherein the combined light amplitude signal is the sum of infrared light and a first color light comprising one or more colors of the color light amplitude signal. Figure 2A In the universe, the first color of light is green, and... Figure 2B In this context, the primary color is white. One or more processors are further configured to determine the infrared signal by subtracting the color light amplitude signal from the combined light amplitude signal.

[0103] exist Figure 2A and Figure 2B In the two examples shown, a color light amplitude is generated based on filtered visible light signals from a first group (11A, 11B) of multiple monochromatic channels 11, and a combined light amplitude signal is generated based on a single combined color channel (12A, 12B) of multiple combined color channels, wherein the first group (11A, 11B) of multiple monochromatic channels 11 is arranged near the single combined color channel (12A, 12B). One or more processors 2 are configured to determine the color light amplitude signal by averaging the filtered visible light signals from the first group (11A, 11B) or by interpolating between the filtered visible light signals from the first group (11, 11B). The determined color light amplitude signal is an approximation of a first color combined with infrared light from the multiple combined color channels. Figure 2C The illustration shows different examples of how the first group (11A, 11B) of multiple monochrome channels 1 are arranged relative to each of the combined color channels (12A, 12B). Figure 2C In all three examples shown, the first group (11A, 11B) of the monochrome channel (11) constitutes the color filter channel neighborhood, and the color filter channel neighborhood is as follows:Figure 2C In example (I), the color filter channel neighborhood 11A is a four-neighbor color filter channel arrangement, where each of the four neighbors in the single filter channel 11A outputs green light, which also corresponds to the first color of the combined filtered light signal. In example (II), the color filter channel neighborhood 11A is a diagonal-neighbor color filter channel arrangement, and in example (III), the color filter channel neighborhood 11A is an eight-neighbor color filter channel arrangement.

[0104] Figure 3A , Figure 3B , Figure 3C and Figure 3D Fig. illustrates an example of a combined scan image 20 determined based on the infrared signal 24 and the visible signals (51A, 51B).

[0105] In Figure 3A , the visible light signal 22 (e.g., a filtered visible light signal) contains surface reflections, i.e., surface information, provided by the emitted white light 51A by the handheld intraoral scanning device 10, and the infrared signal 24 provided by the emitted infrared light 52. In Figure 3A , the combined scan information 20 contains a subtraction of the infrared signal 24 from the visible light signal 22, and wherein the visible light signal 22 is used to determine a 3D surface model 29 of the dentition 80. The combined scan information 20 contains enhanced internal structures represented by the restoration 26A, which is not visible in the infrared signal 24 but can be easily identified in the combined scan information 20. The combined scan information 20 can be mapped onto the 3D surface model 29 by the one or more processors 2, such that the combined scan information provides three-dimensional information about the internal regions of the dentition 80.

[0106] In Figure 3B , the visible light signal 22 contains excitation fluorescence information provided by the emitted blue light 51B by the handheld intraoral scanning device 10, and in this example, the combined scan information 20 contains a subtraction of the infrared signal 24 from the visible light signal 22, and wherein the visible light signal 22 is used to apply the fluorescence information on the 3D surface model 29 of the dentition 80. On the infrared image 24, the caries lesion 27 is hardly visible, however, on the combined image 20, the visibility of the caries lesion has been improved.

[0107] Figure 3C Fig. illustrates an example similar to Figure 3B , however, Figure 3C , the combined scan information 20 in Figure 3CIn this example, the synthetic scan information 20 includes a sum of the green fluorescence information 22 and the infrared signal 24. In this example, the synthetic scan information 20 includes enhanced texture information about the enamel 28A and the dentin 28B, and as a result, the dentin-enamel junction (DEJ) becomes more easily visible due to the improved contrast in the synthetic scan information image 20. It is readily seen that the enamel 28A and the dentin 28B are more clearly seen in the synthetic scan information image 20 than in the infrared signal 24. In another example, the synthetic scan information includes a sum of the infrared signal 24, the green fluorescence information 22, and the red fluorescence information 22, and the synthesis also shows improved visibility of the DEJ relative to conventional or enhanced fluorescence information (or relative to the infrared signal 24).

[0108] Figure 3B An example is illustrated in which the projector unit 5 emits visible light including blue wavelengths 51B and white wavelengths 51A, and non-visible light including infrared wavelengths. In this example, the emitted blue wavelengths 51B excite green fluorescence information 22B and red fluorescence information 22C. In this example, the visible light signal (22A, 22B, 22C) includes surface information provided by the emitted white wavelengths 22A and green 22B and red 22C fluorescence provided by the emitted blue wavelengths. The surface information is used to generate or update the 3D model 29, and the fluorescence information (21A, 21C) is used to determine the synthetic scan information 20. In the present example, the one or more processors 2 are configured to determine a first difference between the infrared signal 24 and the green fluorescence information 22B and a second difference between the infrared signal and the red fluorescence information 22C, and the synthetic scan information 20 includes a sum of the first difference and the second difference. The enhanced internal structure involves a carious lesion, which becomes more visible compared to the infrared signal 24 and in the Figure 3B In the illustrated example, the carious lesion is more visible.

[0109] Figure 4 An example of a scan sequence 50 is illustrated. In a first time period 56, the emitted visible light 51A, e.g., white light, is constantly on at a constant power level. During a second time period 55, the emitted visible light includes two modalities (51, 51B), e.g., white light 51A and ultraviolet light 51B. During the second time period, the one or more processors 2 are configured to asynchronously turn on and off the ultraviolet light 51B and the infrared light 52, while the white light 51A is constantly on at two different power levels, i.e., a first power level 51A’ and a second power level 51A”. For example, the white light 51A, i.e., the first visible light 51A, is emitted at the second power level 51” during the first time period 56. When the ultraviolet light 51B, i.e., the second visible light 51B, is emitted and / or the infrared light is emitted, the white light, i.e., the first visible light 51A, is emitted at the first power level 51A’ which is substantially lower than the second power level 51A”. Figure 4Without being illustrated, a third power level of the white light 51A can be introduced. The white light 51A is emitted at the third power level at the same time as the infrared light 52 is emitted by the projector unit, and the third power level is greater than the first power level 51A’ but lower than the second power level 51A”. The varying low power levels, i.e. the first and third power levels, provide the benefit of being able to specifically adjust the white light level for generating fluorescence information and / or infrared signals with a sub-surface scattering level that neither destroys the fluorescence information nor the infrared information, but provides a better visibility of the actual dental object, e.g. the tooth, in combination with the fluorescence information and / or the infrared information.

[0110] While some embodiments have been described and shown in detail, the present disclosure is not limited to such details but can be practiced with the subject matter defined in the appended claims using other embodiments and by making structural and functional modifications thereof. In particular, it is to be understood that embodiments can be utilized without departing from the scope of the present invention.

[0111] Benefits, other advantages, and solutions to problems have been described herein with regard to specific embodiments. However, the benefits, advantages, solutions to problems and any one or more components / elements of any of the claims or the application should not be construed as critical, required or essential to all the claims or the application. Accordingly, the scope of the application is defined by the appended claims rather than the description and the exemplary embodiments. The description and the exemplary embodiments are not intended to limit or restrict the scope of the claims in any way. It is therefore expressly intended that the claims shall cover all readily equivalents as would be covered by the claims but for the statutory limitations. In this regard, no admission is made that a particular reference, or a combination of any references, is material to determining patentability. It is the applicant's position, to the extent indicated by express incorporation of references into the claims, that any reference can serve as a basis for a proper written statement pursuant to 37 C.F.R. § 1.97 and 37 C.F.R. § 1.98.

[0112] The structural features of the apparatus described above in the detailed description and / or claims can be combined with the steps of the method when appropriately replaced by corresponding processes.

[0113] "comprise," "including," and / or "comprising" when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements can be present. In addition, the word "connected" or "coupled" as used herein can include wirelessly connected or coupled. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. The steps of any disclosed methods need not be performed in the exact order detailed herein unless specifically stated.

[0114] It is to be understood that the singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise. It is to be understood that the term "comprising" as used herein is not intended to exclude other features, integers, steps, operations, elements, and / or components but to add additional features, integers, steps, operations, elements, and / or components to the methods and / or compositions described herein. It is to be understood that where the application, or any feature thereof, is / are claimed and / or described herein as meaning "at least one of A and / or B," it should be understood that this implies that A is present, B is present, or both A and B are present.

[0115] The claims are not intended to be limited to the aspects shown herein, but are to be accorded the full scope consistent with the language of the claims wherein only the claims are limiting, unless specified otherwise. An element proceeded by "comprises... a," "has... a," "includes... a," or "contains... a" does not, without further qualification, preclude the existence of additional similar elements or further elements in the composition, method, or process of the application. The values set forth in the examples are approximate, and thus do not limit the scope of the application. All publications and patents are herein incorporated by reference to the same extent as if each individual publication or patent application was specifically and individually indicated to be incorporated by reference. Wherein in the disclosure, numbers are designated as "about X," it is understood that the value of X is approximate, and thus does not limit the scope of the application.

[0116] Item 1. An intraoral scanning system configured to determine 3D data of a dental object in an oral cavity, the intraoral scanning system comprising: an intraoral scanner comprising: a projector unit configured to emit visible light and infrared light during a scanning sequence, an image sensor unit configured to acquire, from at least the dental object, a visible light signal and an infrared signal resulting from the emitted visible light and the emitted infrared light, respectively; and one or more processors configured to: controlling power to the projector unit such that a first power level of infrared light emitted during a first time period of the scan sequence is lower than a second power level of infrared light emitted during a second time period of the scan sequence; and determining 3D data based on visible light signals acquired during the first time period and determining internal region information of the dental object based on infrared signals acquired during the second time period.

[0117] 2. The intraoral scanning system of item 1, wherein the power to the projector unit is a supplied power to the projector unit.

[0118] 3. The intraoral scanning system of any of the preceding items, wherein a power ratio between the first power level and the second power level is between ¼ to ½, 1 / 8 to ½, 1 / 10 to ½, 1 / 20 to ½, or 1 / 10 to ¼.

[0119] 4. The intraoral scanning system of any of the preceding items, wherein during the first time period, the one or more processors are configured to determine sub-internal region information based on the infrared signals and augment the 3D data by a combination of the visible light signals and the sub-internal region information.

[0120] 5. The intraoral scanning system of any of the preceding items, wherein during the second time period, the one or more processors are configured to determine internal region information based on the infrared signals and determine a composite image based on the infrared signals and the visible light signals, and wherein the composite image contains augmented internal region information.

[0121] 6. The intraoral scanning system of any of the preceding items, wherein the first power level of infrared light emitted during the first time period is lower than a noise floor level of the image sensor unit.

[0122] 7. The intraoral scanning system of any of the preceding items, wherein the one or more processors are configured to control the projector unit during the scan sequence and: during the first time period, the emitted visible light contains a first visible light turned on at a constant power level while infrared light is constantly on at the first power level; and during the second time period, the emitted visible light contains a second visible light turned on and off at a first pulse repetition rate while infrared light is constantly on at the second power level and the first visible light is turned on and off at a second pulse repetition rate that is asynchronous to the on / off switching of the first visible light.

[0123] 8. The intraoral scanning system of item 7, wherein the one or more processors are configured to vary the first pulse repetition rate during the second time period based on a scan mode.

[0124] 9. The intraoral scanning system of any of items 7 and 8, wherein the first time period and the second time period repeat throughout a scan sequence, and wherein the second time period repeats within 100 ms, within 200 ms, or within 500 ms.

[0125] 10. The intraoral scanning system of any of items 7 to 9, wherein the second time period is between 30 ms and 50 ms, between 30 ms and 40 ms, approximately 30 ms or approximately 40 ms, approximately 50 ms or approximately 50 ms.

[0126] 11. The intraoral scanning system of any of items 7 to 10, wherein the first visible light comprises a wavelength corresponding to white light, and wherein the second visible light comprises a wavelength corresponding to blue light.

[0127] 12. The intraoral scanning system of any of the preceding items, wherein the projector unit is configured to emit visible light comprising white light and blue light during a scan sequence, wherein a first pulse repetition rate of white light is different from a second pulse repetition rate of blue light, and wherein infrared light is constantly on during the first time period and the second time period.

[0128] 13. The intraoral scanning system of item 12, wherein the one or more processors are configured to adjust the first repetition rate and the second repetition rate based on a scan mode of the handheld intraoral scanner.

[0129] 14. The intraoral scanning system of item 12 or 13, wherein the first pulse repetition rate is faster than the second pulse repetition rate.

[0130] 15. The intraoral scanning system of any of the preceding items, wherein the first power level is constant during the first time period, and the second power level is constant during the second time period.

[0131] 16. The intraoral scanning system of any of the preceding items, wherein the intraoral scanner comprises: a filter unit configured to receive visible light signals and infrared signals from at least a dental object, and wherein the filter unit is configured to transmit filtered visible light signals and combined filtered light signals, wherein the combined filtered light signals comprise a combination of a first color light of the visible light signals and infrared light of the infrared signals, and wherein the filter unit comprises: a plurality of single color channels configured to output the filtered visible light signals; and a plurality of combined color channels configured to output the combined filtered light signals, an image sensor unit configured to acquire the filtered visible light signal and the combined filtered light signal, and one or more processors configured to: determine an infrared signal based on a subtraction of one or more color lights of the combined filtered light signal from the filtered visible light signal; and determine 3D data of the dental object based on at least the filtered visible light signal.

[0132] 17. The intraoral scanning system according to any one of the preceding items, wherein the one or more processors are configured to determine fluorescence information of the dental object from the visible light signal.

[0133] 18. The intraoral scanning system according to any one of the preceding items, wherein the inner region is determined by composite scan information comprising a difference between the infrared signal and the visible light signal.

[0134] 19. The intraoral scanning system according to item 17 or 18, wherein the fluorescence information comprises green fluorescence information and / or red fluorescence information.

[0135] 20. The intraoral scanning system according to item 19, wherein the one or more processors are configured to determine a first difference between the infrared signal and the green fluorescence information and a second difference between the infrared signal and the red fluorescence information, and wherein the composite scan information comprises a sum of the first difference and the second difference.

[0136] 21. The intraoral scanning system according to item 19, wherein the composite scan information comprises a sum of the infrared signal, the green fluorescence information, and the red fluorescence information.

[0137] 22. The intraoral scanning system according to any one of the preceding items, wherein the one or more processors are configured to determine the 3D data based on one or more colors of the visible light signal.

[0138] 23. The intraoral scanning system according to item 22, wherein the scan sequence is a full scan of at least the upper jaw and / or the lower jaw of the oral cavity.

[0139] 24. The intraoral scanning system according to any one of the preceding items, wherein a power level of the infrared light is set to a first power level during a main time period and to a second power level during a secondary time period, wherein the first power level is lower than the second power level.

[0140] 25. The intraoral scanning system according to any one of the preceding items, wherein the emitted visible light comprises visible light pulses, and wherein the emitted infrared light is not pulsed.

[0141] 26. An intraoral scanning system configured to determine 3D data of a dental object in an oral cavity, the intraoral scanning system comprising: an intraoral scanner comprising: a projector unit configured to emit visible light and infrared light during a scan sequence, an image sensor unit configured to acquire from at least the dental object a visible light signal and an infrared signal resulting from the emitted visible light and the emitted infrared light, respectively; and one or more processors configured to: control a power level of the emitted visible light to a first power level during a first time period of the scan sequence, and during a second time period, the power level of the emitted visible light is switched between the first power level and a second power level, and wherein the first power level is lower than the second power level, and wherein the emitted infrared light is modulated at a given frequency; determine the 3D data based on the visible light signal acquired during the first time period, and determine an internal region of the dental object based on the infrared signal acquired during the second time period.

Claims

1. An intraoral scanning system configured to determine 3D data of a dental object in an oral cavity, the intraoral scanning system comprising: an intraoral scanner comprising: a projector unit configured to emit visible light and infrared light during a scan sequence, an image sensor unit configured to acquire, from at least the dental object, a visible light signal and an infrared signal resulting from the emitted visible light and the emitted infrared light, respectively; and one or more processors configured to: control a power level of the emitted infrared light to a first power level during a first time period of the scan sequence, and during a second time period, the power level of the emitted infrared light is toggled between the first power level and a second power level, and wherein the first power level is lower than the second power level; and determine 3D data based on the visible light signal acquired during the first time period, and determine internal region information of the dental object based on the infrared signal acquired during the second time period.

2. The intraoral scanning system of claim 1, wherein, the one or more processors are configured to toggle between the first power level and the second power level during the second time period.

3. The intraoral scanning system according to any one of the preceding claims, wherein, during the first time period, the one or more processors are configured to determine sub-internal region information based on the infrared signal, and augment the 3D data by a combination of the visible light signal and the sub-internal region information.

4. The intraoral scanning system according to any one of the preceding claims, wherein, during the second time period, the one or more processors are configured to determine internal region information based on the infrared signal, and determine a composite image based on the infrared signal and the visible light signal, and wherein the composite image comprises augmented internal region information.

5. The intraoral scanning system according to any one of the preceding claims, wherein, the first power level of the emitted infrared light during the first time period is lower than a noise floor level of the image sensor unit.

6. The intraoral scanning system according to any one of the preceding claims, wherein, the one or more processors are configured to control the projector unit during the scan sequence, and: during the first time period, the emitted visible light comprises a first visible light turned on at a constant power level, while the infrared light is constantly turned on at the first power level; and during the second time period, the emitted visible light comprises a second visible light turned on and off at a second pulse repetition rate, and the first visible light is turned on and off asynchronously to the on / off toggling of the second visible light at a first pulse repetition rate, and wherein the power level of the infrared light is turned up when the first visible light and the second visible light are turned off, and the power level of the infrared light is turned down when the first visible light or the second visible light is turned on, and wherein the power level of the infrared light is turned up and down between the first power level and the second power level.

7. The intraoral scanning system of claim 6, wherein, the first visible light comprises wavelengths corresponding to white light, and wherein the second visible light comprises wavelengths corresponding to blue light. the first visible light comprises wavelengths corresponding to white light, and wherein the second visible light comprises wavelengths corresponding to blue light.

8. The intraoral scanning system according to any one of the preceding claims, wherein, The projector unit is configured to emit visible light comprising white light and blue light during the scan sequence, wherein a first pulse repetition rate of the white light is different from a second pulse repetition rate of the blue light, and wherein the infrared light is constantly on during the first and second time periods.

9. The intraoral scanning system of claim 8, wherein, The one or more processors are configured to adjust the first repetition rate and the second repetition rate based on a scan mode of the handheld intraoral scanner.

10. The intraoral scanning system according to any one of the preceding claims, wherein, The intraoral scanner comprises: a filter unit configured to receive the visible light signal and the infrared signal from at least the dental object, and wherein the filter unit is configured to transmit a filtered visible light signal and a combined filtered light signal, wherein the combined filtered light signal comprises a combination of a first color light of the visible light signal and infrared light of the infrared signal, and wherein the filter unit comprises: a plurality of single color channels configured to output the filtered visible light signal; and a plurality of combined color channels configured to output the combined filtered light signal; an image sensor unit configured to acquire the filtered visible light signal and the combined filtered light signal, and wherein the one or more processors are configured to: determine an infrared signal based on a subtraction of one or more color lights of the combined filtered light signal from the filtered visible light signal; and determine 3D data of the dental object based on at least the filtered visible light signal.

11. The intraoral scanning system according to any of the preceding items, wherein, The inner region is determined by a combined scan information comprising a difference between the infrared signal and the visible light signal.

12. The intraoral scanning system according to item 10 or 11, wherein, The fluorescence information comprises green fluorescence information and / or red fluorescence information.

13. The intraoral scanning system of item 12, wherein, The one or more processors are configured to determine a first difference between the infrared signal and the green fluorescence information and a second difference between the infrared signal and the red fluorescence information, and wherein the combined scan information comprises a sum of the first difference and the second difference.

14. The intraoral scanning system of item 12, wherein, The combined scan information comprises a sum of the infrared signal, the green fluorescence information, and the red fluorescence information.

15. The intraoral scanning system according to any of the preceding items, wherein, The one or more processors are configured to determine the 3D data based on one or more colors of the visible light signal.

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