Virtual Dental Model Alignment Using 2D Photographs
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Solution Overview
Problem
Current dental simulation software lacks patient-specific settings for jaw movement simulations, relying on average values and requiring radiographic imaging, which is undesirable due to radiation exposure and difficulties in determining the hinge axis and condylar guidance.
Innovation Solution
A method to align a virtual dental model with a virtual hinge axis using 2D photographs, correcting for perspective and field of view, and setting the axis of rotation to simulate jaw movement without radiographic imaging, involving calibration devices, telecentric lenses, zoom lenses, and post-processing to determine the hinge axis and condylar guidance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If radiographic imaging is used to determine the position of the temporal mandibular joint and estimate the hinge axis, then measurement precision is improved, but the patient is exposed to higher radiation dose
Solution Approach 1:
The patent extracts the hinge axis determination process from radiographic imaging and relocates it to 2D photograph analysis combined with virtual articulator simulation. By taking out the harmful radiographic step and replacing it with non-ionizing 2D imaging and computational methods, the system maintains measurement capability while eliminating radiation exposure
Solution Approach 2:
The patent creates a virtual copy of the articulator and jaw movement mechanics through software simulation. Instead of using physical articulators that require radiographic data, a digital replica is constructed from 2D photographs and anatomical landmarks, allowing hinge axis determination without radiation while preserving the functional simulation capability
2Measurement precision
If 2D x-ray images are used to determine hinge axis position, then measurement capability is improved, but perspective and viewing angle determination becomes difficult
Solution Approach 1:
The patent introduces facial landmarks and anatomical reference points as intermediary elements that bridge the gap between 2D image data and 3D spatial relationships. These intermediaries (visible facial features, tooth positions, and their projections) serve as measurable references that eliminate the need to directly determine perspective and viewing angle, as the virtual articulator automatically calculates these parameters from the landmark coordinates
Solution Approach 2:
The patent replaces the mechanical/physical process of determining perspective and viewing angle through geometric analysis with a computational approach. The virtual articulator software automatically calculates the three-dimensional hinge axis position and condylar guidance angles from two-dimensional landmark coordinates using mathematical algorithms, eliminating the difficulty of manual perspective determination
3Reliability
If virtual articulators with patient-specific settings are implemented, then simulation accuracy is improved, but device complexity increases
Solution Approach 1:
The patent creates a universal virtual articulator platform that can handle multiple functions: hinge axis determination, condylar guidance measurement, jaw movement simulation, and treatment planning. This single integrated system replaces multiple separate tools (physical articulators, radiographic equipment, manual measurement devices), reducing overall system complexity while maintaining patient-specific accuracy through programmable parameters
Data Source
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AI summary
Disclosed is a method for setting the axis of rotation between a virtual maxillary model and a virtual mandible model to a virtual hinge axis representing the axis of rotation of the mandibular condyles, the method comprises the steps of, obtaining at least one 2D photograph of the face of a patient comprising at least one facial feature, obtaining a virtual dental model comprising the virtual maxillary model and the virtual mandible model representing at least a part of the dental situation of the patient, aligning the virtual dental model with the at least one facial feature, determining the virtual hinge axis based on the at least one 2D photograph, and setting the axis of rotation to the virtual hinge axis.