Gold-porcelain combined tooth strength testing and performance improving method

Abstract

The invention relates to the technical field of tooth strength testing, in particular to a gold-porcelain combined tooth strength testing and performance improving method. The method comprises the following steps: acquiring stress data of the gold-porcelain combined teeth in different stress directions at various oral temperatures; obtaining a strength performance value according to the stress data of the teeth in each stress direction under each oral cavity temperature; determining a target stress direction and a non-target stress direction according to the difference of the strength performance values of the teeth in the same stress direction at different oral temperatures; obtaining a crack propagation characteristic value according to the difference of the stress data change characteristics of the curve segments corresponding to different stress directions under each oral cavity temperature; based on the difference between the crack propagation characteristic values of the teeth in the target stress direction and the non-target stress direction under each oral cavity temperature, obtaining an anti-fracture performance value; and combining the strength performance value and the fracture resistance value to evaluate the comprehensive strength performance of the teeth. According to the invention, the strength detection result of the gold-porcelain combined tooth can accurately reflect the real performance of the gold-porcelain combined tooth in an actual scene.

Description

Technical Field

[0001] The present invention relates to the technical field of tooth strength testing, and in particular to a method for testing the strength of a metal-ceramic bonded tooth and improving its performance. Background Art

[0002] With the continuous advancement of dental restoration technology, metal-ceramic composites (i.e., restorations that combine metal and porcelain materials) have gained widespread application in the field of dental restoration. This material combines the strength of metal with the aesthetics of porcelain, meeting patients' demands for dental restorations that combine both aesthetic appeal and mechanical strength. Metal-ceramic composites are commonly used in clinical treatments such as tooth defects, crown restorations, and bridge restorations, and exhibit excellent biocompatibility and corrosion resistance. However, their strength still has certain limitations. Particularly during long-term use, a potential problem with metal-ceramic composites is that while the porcelain layer offers a good appearance, it is relatively brittle and prone to fracture when subjected to high chewing forces.

[0003] During the actual eating process, the strength and temperature of the food put into the mouth are different each time, so the chewing force and oral temperature of the teeth will be affected by a variety of foods. Teeth in different positions may be subjected to chewing forces in different directions and be at different oral temperatures. Therefore, performance testing under only a single condition will result in the test results being unable to reflect the true performance of the strength of the metal-ceramic bonded teeth in actual scenarios. Summary of the Invention

[0004] In order to solve the problem that the test results of existing methods for testing the strength of metal-porcelain bonded teeth cannot reflect the actual performance of the strength of metal-porcelain bonded teeth in actual scenarios, the purpose of the present invention is to provide a method for testing the strength of metal-porcelain bonded teeth and improving their performance. The technical solutions adopted are as follows: The present invention provides a method for testing the strength and improving the performance of a metal-ceramic bonded tooth, the method comprising the following steps: Obtain stress data of metal-ceramic bonded teeth in different directions under various oral temperatures; Determine the tooth fracture moment and initial fracture moment based on the stress data changes of the teeth in each force direction at each oral temperature; obtain the strength performance value of the teeth in each force direction at each oral temperature based on the tooth fracture moment and initial fracture moment in each force direction at each oral temperature; determine the target force direction and non-target force direction based on the difference in the strength performance value of the teeth in the same force direction at different oral temperatures; Based on the differences in stress data variation characteristics of curve segments corresponding to different stress directions at each oral temperature, the crack growth characteristic value of the tooth in each stress direction at each oral temperature is obtained. The curve segments are obtained by dividing the time period between the initial fracture moment and the tooth fracture moment according to the magnitude of the stress data. Based on the differences in the crack growth characteristic values ​​of the tooth in the target stress direction and the non-target stress direction at each oral temperature, as well as the crack growth characteristic value in the non-target stress direction, the fracture resistance value of the tooth at each oral temperature is obtained. The comprehensive strength performance of the tooth is evaluated by combining the strength performance value and the fracture resistance performance value.

[0005] Preferably, the method of determining the tooth fracture moment and the initial fracture moment according to the stress data changes of the tooth in each force direction at each oral temperature includes: For any oral temperature: Arrange the stress data of the tooth in the candidate direction in chronological order to obtain a stress data sequence in the candidate direction; determine the time corresponding to the maximum value in the stress data sequence as the tooth fracture time; Determining the last moment of the rising phase of the data value in the stress data sequence as the initial fracture moment; The candidate direction is any force direction.

[0006] Preferably, the strength performance values ​​of the teeth in various force directions at various oral temperatures include: For any oral temperature: The normalized result of the product of the maximum value in the stress data sequence and the time from the start of stress application to the moment of tooth fracture in the candidate direction is used as the endurance performance value of the tooth in the candidate direction at any oral temperature; The normalized result of the product of the stress data at the initial fracture moment of the tooth in the candidate direction and the proportion of the time from the start of stress to the initial fracture moment of the tooth in the candidate direction is used as the fracture difficulty of the tooth in the candidate direction at any oral temperature; Combining the endurance performance value and the fracture difficulty, the strength performance value of the tooth in the candidate direction at any oral temperature is obtained, the endurance performance value is positively correlated with the strength performance value, and the fracture difficulty is negatively correlated with the strength performance value.

[0007] Preferably, determining the target force direction and the non-target force direction according to the difference in strength performance values ​​of the teeth in the same force direction at different oral temperatures includes: According to the difference in strength performance values ​​of teeth in the same force direction at different oral temperatures, the strength difference values ​​of teeth in each force direction at different oral temperatures are obtained; Normalizing the inverse proportion of the strength difference value to determine the crack propagation difficulty of the tooth in each force direction; The force direction with a crack extension difficulty less than a preset difficulty threshold is taken as the target force direction, and the force direction with a crack extension difficulty greater than or equal to the preset difficulty threshold is taken as the non-target force direction.

[0008] Preferably, obtaining the curve segments corresponding to different force directions at various oral temperatures includes: For any oral temperature: The time period between the initial fracture moment and the fracture moment of the tooth in the candidate direction at any oral temperature is recorded as the crack propagation time period in the candidate direction; The crack propagation time period is divided according to the peaks and troughs on the fitting curve to obtain multiple curve segments corresponding to different force directions at any oral temperature. The fitting curve is obtained by curve fitting the stress data of the crack propagation time period of the tooth in the candidate direction at any oral temperature.

[0009] Preferably, obtaining the crack extension characteristic value of the tooth in each stress direction at each oral temperature according to the difference between the stress data change characteristics of the curve segments corresponding to different stress directions at each oral temperature includes: For any oral temperature: The crack growth uniformity factor of the tooth in the candidate direction at any oral temperature is obtained based on the difference between the stress change values ​​of different curve segments in the candidate direction except the last curve segment at any oral temperature, and the difference between the stress change values ​​is negatively correlated with the crack growth uniformity factor; wherein the stress change value of each curve segment is the range value of the stress data of each curve segment; Obtaining the crack growth resistance value of the tooth in the candidate direction at any oral temperature according to the stress change rate of each curve segment corresponding to the candidate direction at any oral temperature; wherein the stress change rate of each curve segment is the ratio of the stress change value of each curve segment to the duration of the same curve segment; The crack growth characteristic value of the tooth in the candidate direction at any oral temperature is obtained by combining the crack growth uniformity factor, the crack growth resistance value and the duration of the crack growth time period of the tooth in the candidate direction at any oral temperature.

[0010] Preferably, obtaining the crack growth resistance value of the tooth in the candidate direction at any oral temperature according to the stress change rate of each curve segment corresponding to the candidate direction at any oral temperature includes: According to the stress change rate of the last curve segment corresponding to the candidate direction at any oral temperature and the difference between the stress change rates of the last curve segment and the other curve segments, the crack growth resistance value of the tooth in the candidate direction at any oral temperature is obtained, and the stress change rate of the last curve segment and the difference between the stress change rates are negatively correlated with the crack growth resistance value.

[0011] Preferably, the combining of the crack growth uniformity factor, the crack growth resistance value, and the duration of the crack growth time period of the tooth in the candidate direction at any oral temperature to obtain the crack growth characteristic value of the tooth in the candidate direction at any oral temperature includes: The product of the normalized value of the duration of the crack propagation time period of the tooth in the candidate direction at any oral temperature, the crack propagation uniformity factor and the crack propagation resistance value is used as the crack propagation characteristic value of the tooth in the candidate direction at any oral temperature.

[0012] Preferably, the tooth fracture resistance value at each oral temperature is obtained based on the difference in crack extension characteristic values ​​of the tooth in the target stress direction and the non-target stress direction at each oral temperature and the crack extension characteristic value in the non-target stress direction, including: For any oral temperature: The difference between the mean of the crack extension characteristic values ​​of the tooth in all target stress directions and the mean of the crack extension characteristic values ​​in all non-target stress directions at any oral temperature is recorded as the first difference; The fracture resistance value of the tooth at any oral temperature is obtained based on the mean of the crack extension characteristic values ​​of the tooth in all non-target stress directions at any oral temperature, the number of non-target stress directions and the first difference. The mean of the crack extension characteristic values ​​of all non-target stress directions is positively correlated with the fracture resistance value, and the number of non-target stress directions and the first difference are negatively correlated with the fracture resistance value.

[0013] Preferably, the combined strength performance value and the fracture resistance performance value are used to evaluate the comprehensive strength performance of the tooth, including: The product of the fracture resistance value of the tooth at each oral temperature and the average value of the strength performance value of the tooth in all force directions is respectively used as the first characteristic value of each oral temperature; determining a normalized result of an average value of the first characteristic values ​​of all oral temperatures as a comprehensive intensity index; If the comprehensive strength index is greater than the preset strength threshold, it is determined that the strength performance of the metal-porcelain bonded tooth meets the requirements; if the comprehensive strength index is less than or equal to the preset strength threshold, it is determined that the strength performance of the metal-porcelain bonded tooth does not meet the requirements.

[0014] The present invention has at least the following beneficial effects: The present invention first collects stress data of metal-porcelain teeth in different stress directions at different oral temperatures, and evaluates the strength performance of teeth under different oral temperature conditions based on the changes in stress data of teeth in different stress directions at different oral temperatures, and divides the stress direction into target stress direction and non-target stress direction; by analyzing the difference in crack propagation characteristic values ​​between the target stress direction and the non-target stress direction, the fracture resistance of metal-porcelain teeth in different stress directions can be accurately evaluated; finally, the comprehensive strength performance of the teeth is evaluated by combining the strength performance value and the fracture resistance performance value, thereby improving the accuracy of the comprehensive strength performance evaluation results of metal-porcelain bonded teeth, so that the strength test results of metal-porcelain bonded teeth can accurately reflect the true performance of the strength of metal-porcelain bonded teeth in actual scenarios, thereby effectively reducing the risk of tooth damage, extending its service life, and thus improving the oral health and comfort of the wearer. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] In order to more clearly illustrate the technical solutions and advantages of the embodiments of the present invention or the prior art, the following briefly introduces the drawings required for use in the embodiments or the prior art descriptions. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0016] Figure 1 This is a flow chart of a method for testing the strength and improving the performance of metal-ceramic bonded teeth provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0017] In order to further illustrate the technical means and effects adopted by the present invention to achieve the predetermined purpose of the invention, the following is a detailed description of a metal-ceramic bonded tooth strength testing and performance improvement method proposed in accordance with the present invention in conjunction with the accompanying drawings and preferred embodiments.

[0018] Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0019] The specific scheme of the metal-porcelain bonded tooth strength testing and performance improvement method provided by the present invention is described in detail below with reference to the accompanying drawings.

[0020] An embodiment of a method for testing the strength and improving the performance of a metal-ceramic bonded tooth: This embodiment proposes a method for testing the strength and improving the performance of metal-ceramic bonded teeth. Figure 1As shown, a method for testing the strength and improving the performance of a metal-ceramic bonded tooth in this embodiment includes the following steps: Step S1, obtaining stress data of metal-ceramic bonded teeth in different stress directions at various oral temperatures.

[0021] The chewing force in the mouth is not constant and is affected by many factors, such as the temperature of the food, the way the food is chewed (light chewing, heavy chewing), and the individual's chewing habits. For example, the pressure exerted on the teeth by hard foods (such as nuts and bones) and soft foods (such as bread and vegetables) is very different, and the force applied to the teeth is in different directions. In addition, the temperature in the mouth fluctuates with the temperature of food and drinks. Therefore, this change cannot be fully simulated by a single static strength test.

[0022] When a metal-ceramic bonded tooth fractures in the mouth, the crack will initially propagate in the direction of weaker force (such as microcracks in the enamel), and will not necessarily lead to the entire tooth breaking. Stronger teeth typically exhibit a more uniform fracture pattern, and good strength means that cracks propagate more slowly under load. However, if the strength is poor, the crack may suddenly propagate in the direction of weaker force, rapidly leading to the entire tooth breaking.

[0023] This embodiment uses stress data of metal-ceramic teeth in different stress directions at different oral temperatures to analyze the strength performance of tooth materials under different oral temperature conditions; analyzes the difference in crack propagation characteristic values ​​between the target stress direction and the non-target stress direction, evaluates the fracture resistance of metal-ceramic teeth in different stress directions, and finally determines the overall strength performance of metal-ceramic teeth.

[0024] First, in this embodiment, the force directions of the metal-ceramic bonded tooth are set at 0°, 30°, 60°, 90°, 120°, and 150°, and the simulated oral temperatures are set at 10°C, 15°C, 20°C, 25°C, 30°C, 35°C, and 40°C. In specific applications, the implementer can adjust the force direction and oral temperature according to specific circumstances. At any simulated oral temperature, a stress sensor is placed on the metal-ceramic bonded tooth. A pressure is applied to the metal-ceramic bonded tooth in any direction of force, simulating a three-point bending test. The stress sensor records stress data at all times from the start of force application to complete fracture of the metal-ceramic bonded tooth.

[0025] Thus, this embodiment has collected stress data of the metal-ceramic bonded tooth at all times from the beginning of stress application to complete fracture under different stress directions at various oral temperatures.

[0026] Step S2, determine the tooth fracture moment and the initial fracture moment according to the change of the stress data of the teeth in each force direction at each oral temperature; obtain the strength performance value of the teeth in each force direction at each oral temperature based on the tooth fracture moment and the initial fracture moment of the teeth in each force direction at each oral temperature; determine the target force direction and the non-target force direction according to the difference in the strength performance values ​​of the teeth in the same force direction at different oral temperatures.

[0027] In the early stage of the simulation experiment, with the uniform increase of external force, the stress on the metal-ceramic bonded teeth increased linearly. When approaching fracture, the stress on the teeth increased nonlinearly due to the crack expansion. The stress on the teeth suddenly rose to a peak value at the moment of fracture and then dropped sharply. The temperature in the oral cavity will fluctuate with the temperature of food and drink. The smaller the strength difference of a certain force direction of the teeth under different oral temperature environments, the smaller the strength performance of the force direction of the teeth at different temperatures, indicating that the force direction of the teeth itself has good toughness and compressive resistance, and it can maintain stable strength in hot and cold food environments. When the strength of the metal-ceramic bonded teeth is poor, the cracks will start to expand from the weaker force direction (such as microcracks in the enamel) and cause the entire tooth to break. Therefore, it is necessary to obtain the target force direction and non-target force direction of the teeth.

[0028] In the At the oral temperature, the teeth In the stress data of the three force directions, when the peak value of the stress data of the metal-ceramic bonded tooth is larger, it means that the first The structural design in each stress direction can effectively disperse and withstand greater pressure; and the longer the nonlinear increase time period of crack expansion, the longer the crack is in the first The expansion in the first force direction is slower, indicating that the The material in the direction of force is more resistant to further crack expansion. The higher the strength of the metal-ceramic bonded tooth is in each direction of force.

[0029] For any oral temperature: Taking any force direction as an example for explanation, the method provided in this embodiment can be used to process other force directions. Specifically, any force direction is recorded as a candidate direction, and the stress data of the tooth in the candidate direction are arranged in chronological order to obtain a stress data sequence of the candidate direction; the moment corresponding to the maximum value in the stress data sequence is determined as the moment of tooth fracture; and the last moment of the rising phase of the data value in the stress data sequence is determined as the initial fracture moment. It should be noted that the last moment of the rising phase of the data value in the stress data sequence in this embodiment is the last moment of the first rising phase of the data value of the tooth from the beginning of force.

[0030] The normalized product of the maximum value in the stress data series and the duration from the onset of stress to the moment of tooth fracture in the candidate direction is used as the tooth's endurance performance value in the candidate direction at the oral temperature. Normalization can be performed using the maximum and minimum value normalization method, or other normalization methods.

[0031] The smaller the stress data at the initial fracture moment of the tooth in the candidate direction, the easier it is for the tooth to fracture in the candidate force direction at the oral temperature. Therefore, the normalized result of the product of the stress data at the initial fracture moment of the tooth in the candidate direction and the ratio of the time period from the start of force application to the initial fracture moment of the tooth in the candidate direction is used as the fracture difficulty of the tooth in the candidate direction at the oral temperature. In this embodiment, the product of the maximum value in the stress data sequence and the time period from the start of force application to the fracture moment of the tooth in the candidate direction and the normalization method of the stress data at the initial fracture moment of the tooth in the candidate direction and the ratio of the time period from the start of force application to the initial fracture moment of the tooth in the candidate direction are processed using the maximum and minimum value normalization method. In specific applications, the implementer may choose other data normalization methods for processing, which will not be elaborated here. The method for obtaining the proportion of the time from the start of force application to the initial fracture moment of the tooth in the candidate direction is: the ratio of the time from the start of force application to the initial fracture moment of the tooth in the candidate direction to the total time from the start of force application to the end of force application is used as the proportion of the time from the start of force application to the initial fracture moment of the tooth in the candidate direction.

[0032] If the fracture difficulty of the tooth in the candidate direction at the oral temperature is smaller, and the endurance performance value of the tooth in the candidate force direction at the oral temperature is larger, it means that the strength performance value of the tooth in the candidate force direction at the oral temperature is larger; therefore, this embodiment combines the endurance performance value and the fracture difficulty to obtain the strength performance value of the tooth in the candidate direction at the oral temperature, the endurance performance value is positively correlated with the strength performance value, and the fracture difficulty is negatively correlated with the strength performance value.

[0033] In this embodiment, a specific calculation formula for the strength performance value is given. At the oral temperature, the teeth The strength performance value of each force direction can be expressed as: in, Indicates the At the oral temperature, the teeth Strength performance value in each force direction, Indicates the At the oral temperature, the teeth Endurance performance value in each force direction, Indicates the At the oral temperature, the teeth The difficulty of fracture in each stress direction, represents an exponential function with a natural constant as base, Represents the normalization function.

[0034] When At the oral temperature, the teeth The greater the endurance performance value in each force direction, the At the oral temperature, the teeth The smaller the fracture difficulty in each stress direction, the At the oral temperature, the teeth The greater the strength performance value in each force direction.

[0035] By using the above method, the strength performance values ​​of the teeth in various force directions at various oral temperatures can be obtained.

[0036] The more consistent the strength performance values ​​of the teeth in the same force direction at different oral temperatures, the more stable the strength of the teeth in this force direction can be in hot or cold food environments. Therefore, the strength difference values ​​of each force direction of the teeth at different oral temperatures are determined based on the difference in strength performance values ​​of the teeth in the same force direction at different oral temperatures. Specifically, for any force direction: the absolute value of the difference between the strength performance values ​​of the teeth in this force direction at each two oral temperatures is calculated, and this absolute value is used as the difference between the strength performance values ​​of the teeth in this force direction at these two oral temperatures; there is a difference in strength performance value for the teeth in this force direction at each two oral temperatures, and the cumulative sum of the differences in strength performance values ​​is used as the strength difference value of the teeth in this force direction at different oral temperatures; then, the strength difference value is inversely normalized, and the inversely normalized result is determined as the difficulty of crack growth of the teeth in this force direction. In this embodiment, the specific process of inversely normalizing the strength difference value is: the exponential function value with a natural constant as the base and the negative strength difference value as the exponent is determined as the difficulty of crack growth of the teeth in this force direction. By using the above method, the crack propagation difficulty of the tooth in each force direction can be obtained.

[0037] The force direction with a crack propagation difficulty less than a preset difficulty threshold is used as the target force direction, and the force direction with a crack propagation difficulty greater than or equal to the preset difficulty threshold is used as the non-target force direction. In this embodiment, the preset difficulty threshold is 0.45. In specific applications, the implementer can set it according to specific circumstances.

[0038] At this point, all force directions are divided into target force directions and non-target force directions using the method provided in this embodiment.

[0039] Step S3, based on the difference between the stress data change characteristics of the curve segments corresponding to different force directions at each oral temperature, obtain the crack extension characteristic value of the tooth in each force direction at each oral temperature, and the curve segment is obtained by dividing the time period between the initial fracture moment and the tooth fracture moment according to the size of the stress data; based on the difference between the crack extension characteristic values ​​of the tooth in the target force direction and the non-target force direction at each oral temperature and the crack extension characteristic value in the non-target force direction, obtain the fracture resistance value of the tooth at each oral temperature.

[0040] When a metal-ceramic bonded tooth fractures, the crack often propagates from a weaker stress direction (such as microcracks in the enamel), leading to the entire tooth breaking. Stronger teeth typically exhibit a more uniform fracture pattern, and good strength means that crack propagation is slow under load. If the strength is poor, the crack may suddenly propagate in a weaker stress direction, quickly leading to direct fracture of the entire tooth. Therefore, at the same oral temperature, the greater the difference in stress data series between the target and non-target stress directions of the tooth, the worse the tooth's fracture resistance.

[0041] Teeth with better strength usually exhibit a more uniform fracture pattern, and good strength means that cracks propagate more slowly under load. The above description is manifested in stress data as follows: the fluctuations in stress data in the time period between the initial fracture moment and the tooth fracture moment are relatively uniform and last for a long time.

[0042] Next, this embodiment will be described using an oral temperature as an example. The method provided in this embodiment can be used to process other oral temperatures.

[0043] Specifically, for any oral temperature: The time period between the initial fracture moment of the tooth in the candidate direction and the tooth fracture moment at the oral temperature is recorded as the crack propagation time period in the candidate direction.

[0044] A fitting curve is obtained by curve fitting the stress data of the crack propagation time period of the tooth in the candidate direction at the oral temperature. The horizontal axis of the fitting curve is time and the vertical axis is stress data. Curve fitting is a prior art and will not be described in detail here. The peak points and trough points on the fitting curve are obtained, and the peak points and trough points on the fitting curve are used as dividing points to divide the fitting curve into multiple curve segments. The method for obtaining the peak points and trough points is a prior art and will not be described in detail here.

[0045] Next, the extreme difference value of the stress data of each curve segment is used as the stress change value of each curve segment. Each curve segment has a corresponding stress change value. The closer the stress change values ​​between all curve segments except the last curve segment in the candidate direction at the oral temperature are, the more uniform the fracture pattern of the tooth during the crack propagation period, and the better its strength in the candidate direction. Based on this, according to the difference between the stress change values ​​of different curve segments except the last curve segment in the candidate direction at the oral temperature, the crack propagation uniformity factor of the tooth in the candidate direction at the oral temperature is obtained. The difference between the stress change values ​​is negatively correlated with the crack propagation uniformity factor. In this embodiment, a specific calculation method for the crack propagation uniformity factor of the tooth in the candidate direction at the oral temperature is given: the absolute value of the difference between the stress change values ​​of each two curve segments except the last curve segment in the candidate direction at the oral temperature is calculated respectively, and the absolute value is used as the difference in the stress change values ​​of the corresponding two curve segments. The sum of the differences in the stress change values ​​of all two curve segments except the last curve segment is calculated, and the exponential function value with the natural constant as the base and the negative sum as the exponent is used as the crack propagation uniformity factor of the tooth in the candidate direction at the oral temperature.

[0046] Furthermore, the ratio between the stress change value of each curve segment and the duration of the same curve segment is used as the stress change rate of each curve segment. Each curve segment has a corresponding stress change rate.

[0047] Based on the stress change rate of the last curve segment corresponding to the candidate direction at the oral temperature and the difference between the stress change rates of the last curve segment and other curve segments, the crack growth resistance value of the tooth in the candidate direction at the oral temperature is obtained. The stress change rate of the last curve segment and the difference between the stress change rates are negatively correlated with the crack growth resistance value.

[0048] In this embodiment, a specific calculation formula for the crack growth resistance value is given. At the oral temperature, the teeth The crack growth resistance value in each stress direction can be expressed as: in, Indicates the At the oral temperature, the teeth The crack growth resistance value in each stress direction, Indicates the At the oral temperature, the teeth The stress change rate of the last curve segment corresponding to the force direction, Indicates the At the oral temperature, the teeth The force direction corresponds to the The stress change rate of each curve segment is Indicates the At the oral temperature, the teeth The number of curve segments corresponding to the force direction, Indicates the absolute value sign.

[0049] When At the oral temperature, the teeth The stress change rate of the last curve segment corresponding to the force direction is smaller, and the At the oral temperature, the teeth The smaller the difference in stress change rate between the last curve segment corresponding to the force direction and the other curve segments, the smaller the stress change rate between the last curve segment corresponding to the force direction and the other curve segments. At the oral temperature, the teeth The stronger the crack propagation resistance in the first stress direction, At the oral temperature, the teeth The greater the crack growth resistance value in each force direction.

[0050] Then, the product of the normalized value of the crack propagation time period of the tooth in the candidate direction at the oral temperature, the crack propagation uniformity factor of the tooth in the candidate direction at the oral temperature, and the crack propagation resistance value of the tooth in the candidate direction at the oral temperature is used as the crack propagation characteristic value of the tooth in the candidate direction at the oral temperature. The normalization method of the crack propagation time period is as follows: the ratio of the crack propagation time period of the tooth in the candidate direction at the oral temperature to the total time from the initial moment to the end moment of the force application of the tooth in the candidate direction at the oral temperature is used as the normalized value of the crack propagation time period.

[0051] When the crack propagation characteristic value of the tooth under the non-target force direction is larger, the number of non-target force directions of the tooth is smaller, and the difference in the crack propagation characteristic value between the target force direction and the non-target force direction is smaller, it means that the tooth exhibits a more uniform fracture pattern during the crack propagation process under the non-target force direction, and the crack propagation is slower, which means that the tooth has better fracture resistance.

[0052] In this embodiment, the mean of the crack extension characteristic values ​​of the tooth in all target stress directions at the oral temperature and the mean of the crack extension characteristic values ​​of the tooth in all non-target stress directions at the oral temperature are calculated, and the difference between these two means is recorded as the first difference. Based on the mean of the crack extension characteristic values ​​of the tooth in all non-target stress directions at the oral temperature, the number of non-target stress directions, and the first difference, the fracture resistance value of the tooth at the oral temperature is obtained. The mean of the crack extension characteristic values ​​of all non-target stress directions is positively correlated with the fracture resistance value, and the number of non-target stress directions and the first difference are both negatively correlated with the fracture resistance value.

[0053] In this embodiment, a specific calculation formula for the fracture resistance value is given. The fracture resistance value of teeth at oral temperature can be expressed as: in, Indicates the The fracture resistance of teeth at oral temperature, Indicates the The mean of the crack extension characteristic values ​​of the tooth in all non-target stress directions at the oral temperature, Indicates the The mean of the crack extension characteristic values ​​of the tooth in all target stress directions at the oral temperature, Indicates the number of non-target force directions, Represents an exponential function with a natural constant as its base.

[0054] It represents the first difference. The larger its value is, the greater the overall difference between the crack extension characteristic value of the tooth in the target force direction and the crack extension characteristic value in the non-target force direction is.

[0055] By using the above method, the fracture resistance value of teeth at various oral temperatures can be obtained.

[0056] Step S4: Evaluate the comprehensive strength performance of the tooth by combining the strength performance value and the fracture resistance performance value.

[0057] Good fracture resistance means that teeth can effectively resist the stress applied in daily use (such as chewing, biting, etc.), and even when cracks or damage occur, it is not easy to cause overall fracture; at different oral temperatures, the greater the strength performance value of the teeth in each force direction, it means that the teeth can withstand stress evenly in multiple directions, whether it is chewing, collision or other external forces, and can maintain structural integrity under various force conditions; therefore, the better the fracture resistance of the teeth and the greater the strength performance value of the teeth in different force directions at different oral temperatures, the stronger the comprehensive strength performance of the teeth.

[0058] For any oral temperature, calculate the average strength performance value of the teeth in all force directions at that oral temperature; the product of this average value and the tooth's fracture resistance value at that oral temperature is recorded as the first eigenvalue of that oral temperature. Using this method, the first eigenvalue of each oral temperature can be obtained. The normalized result of the average value of the first eigenvalues ​​of all oral temperatures is determined as the comprehensive strength index. There are many data normalization methods, and implementers can select an appropriate normalization method based on the specific situation to perform normalization processing, so that the normalized result of the average value of the first eigenvalues ​​of all oral temperatures is (0, 1).

[0059] If the combined strength index is greater than a preset strength threshold, the metal-ceramic bond is judged to meet the strength requirements. If the combined strength index is less than or equal to the preset strength threshold, the tooth's fracture resistance is low when subjected to external forces such as chewing and collisions, and the metal-ceramic bond may be prone to cracking, breaking, or chipping. Introducing more high-toughness materials, such as bauxite and zircon, can improve the tooth's fracture resistance, preventing it from cracking when subjected to external forces. In this case, the metal-ceramic bond is judged to be unsatisfactory in terms of strength. If the metal-ceramic bond does not meet the strength requirements, a thin film of an oxide such as Al2O3 or ZrO2 can be sprayed on the metal substrate or ceramic surface to form a transition layer, reducing interface defects and enhancing bonding strength. Introducing high-toughness materials such as bauxite and zircon can significantly improve the tooth's fracture resistance, improve durability, enhance strength performance in different force directions, and improve adaptability to changes in oral temperature. In this embodiment, the preset strength threshold is 0.6. In specific applications, the implementer can set it according to specific circumstances.

[0060] Thus, the method provided in this embodiment has been used to accurately test the strength of metal-ceramic bonded teeth. This test can effectively reduce the risk of tooth breakage and extend its service life, thereby improving the wearer's oral health and comfort.

[0061] This embodiment first collects stress data of metal-ceramic teeth in different stress directions at different oral temperatures, and evaluates the strength performance of the teeth under different oral temperature conditions based on the changes in stress data of the teeth in different stress directions at different oral temperatures, and divides the stress directions into target stress directions and non-target stress directions; by analyzing the differences in crack propagation characteristic values ​​between the target stress directions and the non-target stress directions, the fracture resistance of the metal-ceramic teeth in different stress directions can be accurately evaluated; finally, the comprehensive strength performance of the teeth is evaluated by combining the strength performance value and the fracture resistance performance value, thereby improving the accuracy of the comprehensive strength performance evaluation results of the metal-ceramic bonded teeth, so that the strength test results of the metal-ceramic bonded teeth can accurately reflect the true performance of the strength of the metal-ceramic bonded teeth in actual scenarios, thereby effectively reducing the risk of tooth damage and extending its service life, thereby improving the wearer's oral health and comfort.

[0062] It should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent replacements, improvements, etc. made within the principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for testing the strength and improving the performance of metal-ceramic bonded teeth, characterized in that: The method comprises the following steps: Obtain stress data of metal-ceramic bonded teeth in different directions under various oral temperatures; Determine the tooth fracture moment and initial fracture moment based on the stress data changes of the teeth in each force direction at each oral temperature; obtain the strength performance value of the teeth in each force direction at each oral temperature based on the tooth fracture moment and initial fracture moment in each force direction at each oral temperature; determine the target force direction and non-target force direction based on the difference in the strength performance value of the teeth in the same force direction at different oral temperatures; Based on the differences in stress data variation characteristics of curve segments corresponding to different stress directions at each oral temperature, the crack growth characteristic value of the tooth in each stress direction at each oral temperature is obtained. The curve segments are obtained by dividing the time period between the initial fracture moment and the tooth fracture moment according to the magnitude of the stress data. Based on the differences in the crack growth characteristic values ​​of the tooth in the target stress direction and the non-target stress direction at each oral temperature, as well as the crack growth characteristic value in the non-target stress direction, the fracture resistance value of the tooth at each oral temperature is obtained. The comprehensive strength performance of the tooth is evaluated by combining the strength performance value and the fracture resistance performance value.

2. A method for testing the strength and improving the performance of a metal-ceramic bonded tooth according to claim 1, characterized in that: Determining the tooth fracture moment and initial fracture moment according to the stress data changes of the tooth in each force direction at each oral temperature includes: For any oral temperature: Arrange the stress data of the tooth in the candidate direction in chronological order to obtain a stress data sequence in the candidate direction; determine the time corresponding to the maximum value in the stress data sequence as the tooth fracture time; Determining the last moment of the rising phase of the data value in the stress data sequence as the initial fracture moment; The candidate direction is any force direction.

3. A method for testing the strength and improving the performance of a metal-ceramic bonded tooth according to claim 2, characterized in that: The strength performance values ​​of the teeth in various stress directions at various oral temperatures include: For any oral temperature: The normalized result of the product of the maximum value in the stress data sequence and the time from the start of stress application to the moment of tooth fracture in the candidate direction is used as the endurance performance value of the tooth in the candidate direction at any oral temperature; The normalized result of the product of the stress data at the initial fracture moment of the tooth in the candidate direction and the proportion of the time from the start of stress to the initial fracture moment of the tooth in the candidate direction is used as the fracture difficulty of the tooth in the candidate direction at any oral temperature; Combining the endurance performance value and the fracture difficulty, the strength performance value of the tooth in the candidate direction at any oral temperature is obtained, the endurance performance value is positively correlated with the strength performance value, and the fracture difficulty is negatively correlated with the strength performance value.

4. A method for testing the strength and improving the performance of a metal-ceramic bonded tooth according to claim 2, characterized in that: Determining the target force direction and the non-target force direction according to the difference in strength performance values ​​of the teeth at different oral temperatures in the same force direction includes: According to the difference in strength performance values ​​of teeth in the same force direction at different oral temperatures, the strength difference values ​​of teeth in each force direction at different oral temperatures are obtained; Normalizing the inverse proportion of the strength difference value to determine the crack propagation difficulty of the tooth in each force direction; The force direction with a crack extension difficulty less than a preset difficulty threshold is taken as the target force direction, and the force direction with a crack extension difficulty greater than or equal to the preset difficulty threshold is taken as the non-target force direction.

5. The method for testing the strength and improving the performance of a metal-ceramic bonded tooth according to claim 2, characterized in that: Obtaining the curve segments corresponding to different force directions at various oral temperatures, including: For any oral temperature: The time period between the initial fracture moment and the fracture moment of the tooth in the candidate direction at any oral temperature is recorded as the crack propagation time period in the candidate direction; The crack propagation time period is divided according to the peaks and troughs on the fitting curve to obtain multiple curve segments corresponding to different force directions at any oral temperature. The fitting curve is obtained by curve fitting the stress data of the crack propagation time period of the tooth in the candidate direction at any oral temperature.

6. A method for testing the strength and improving the performance of a metal-ceramic bonded tooth according to claim 5, characterized in that: The method of obtaining the crack extension characteristic value of the tooth in each stress direction at each oral temperature according to the difference between the stress data change characteristics of the curve segments corresponding to different stress directions at each oral temperature includes: For any oral temperature: The crack growth uniformity factor of the tooth in the candidate direction at any oral temperature is obtained based on the difference between the stress change values ​​of different curve segments in the candidate direction except the last curve segment at any oral temperature, and the difference between the stress change values ​​is negatively correlated with the crack growth uniformity factor; wherein the stress change value of each curve segment is the range value of the stress data of each curve segment; Obtaining the crack growth resistance value of the tooth in the candidate direction at any oral temperature according to the stress change rate of each curve segment corresponding to the candidate direction at any oral temperature; wherein the stress change rate of each curve segment is the ratio of the stress change value of each curve segment to the duration of the same curve segment; The crack growth characteristic value of the tooth in the candidate direction at any oral temperature is obtained by combining the crack growth uniformity factor, the crack growth resistance value and the duration of the crack growth time period of the tooth in the candidate direction at any oral temperature.

7. A method for testing the strength and improving the performance of a metal-ceramic bonded tooth according to claim 6, characterized in that: Obtaining the crack growth resistance value of the tooth in the candidate direction at any oral temperature according to the stress change rate of each curve segment corresponding to the candidate direction at any oral temperature includes: According to the stress change rate of the last curve segment corresponding to the candidate direction at any oral temperature and the difference between the stress change rates of the last curve segment and the other curve segments, the crack growth resistance value of the tooth in the candidate direction at any oral temperature is obtained, and the stress change rate of the last curve segment and the difference between the stress change rates are negatively correlated with the crack growth resistance value.

8. The method for testing the strength and improving the performance of a metal-ceramic bonded tooth according to claim 6, characterized in that: Combining the crack growth uniformity factor, the crack growth resistance value, and the duration of the crack growth time period of the tooth in the candidate direction at any oral temperature to obtain the crack growth characteristic value of the tooth in the candidate direction at any oral temperature includes: The product of the normalized value of the duration of the crack propagation time period of the tooth in the candidate direction at any oral temperature, the crack propagation uniformity factor and the crack propagation resistance value is used as the crack propagation characteristic value of the tooth in the candidate direction at any oral temperature.

9. The method for testing the strength and improving the performance of a metal-ceramic bonded tooth according to claim 1, characterized in that: The tooth fracture resistance value at each oral temperature is obtained based on the difference in the crack extension characteristic values ​​of the tooth in the target stress direction and the non-target stress direction at each oral temperature and the crack extension characteristic value in the non-target stress direction, including: For any oral temperature: The difference between the mean of the crack extension characteristic values ​​of the tooth in all target stress directions and the mean of the crack extension characteristic values ​​in all non-target stress directions at any oral temperature is recorded as the first difference; The fracture resistance value of the tooth at any oral temperature is obtained based on the mean of the crack extension characteristic values ​​of the tooth in all non-target stress directions at any oral temperature, the number of non-target stress directions and the first difference. The mean of the crack extension characteristic values ​​of all non-target stress directions is positively correlated with the fracture resistance value, and the number of non-target stress directions and the first difference are negatively correlated with the fracture resistance value.

10. The method for testing the strength and improving the performance of a metal-ceramic bonded tooth according to claim 1, characterized in that: The combined strength and fracture resistance values ​​are used to evaluate the comprehensive strength of the tooth, including: The product of the fracture resistance value of the tooth at each oral temperature and the average value of the strength performance value of the tooth in all force directions is respectively used as the first characteristic value of each oral temperature; determining a normalized result of an average value of the first characteristic values ​​of all oral temperatures as a comprehensive intensity index; If the comprehensive strength index is greater than the preset strength threshold, it is determined that the strength performance of the metal-porcelain bonded tooth meets the requirements; if the comprehensive strength index is less than or equal to the preset strength threshold, it is determined that the strength performance of the metal-porcelain bonded tooth does not meet the requirements.

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