Research On Dental Feature Extraction And Occlusal Assessment In Orthodontic Treatment Plan

Malocclusion has negative effects on both facial appearance and occlusal function. When treating the patients, orthodontists need to use orthodontic indices to diagnose the teeth and evaluate clinical efficacy. Traditional orthodontic indices are based on dental plaster models and much manual measurement is required. Three-dimensional dental models are introduced to measure and assess the teeth precisely. As the necessary prerequisites of occlusion assessment, dental feature extraction and teeth collision detection are studied in this thesis. On this basis, the occlusal assessment method is studied.A teeth feature extraction method based on tensor voting algorithm is put forward. The method extracts candidate feature points from teeth mesh data by applying tensor voting algorithm. Weak feature points are detected and preserved through improving classification method of matrix eigenvalue in the algorithm. Neighborhood search and non-maximum suppression operation are integrated to position teeth features like cusps and incisal ridges precisely.Applying variable radius sphere search method for maxillary and mandibular dentition collision detection, the nearest point of paired jaw teeth can be sought by variable radius sphere search quickly. Signed shortest distance is computed and used to indicate jaw occlusal contact situation, then the result is visualized by occlusion depth map.Combined with the existing clinical orthodontic indices, an occlusion assessment method is proposed. According to the results of dental feature detection, interactive measurement of three-dimension teeth mesh data is done to gain accurate orthodontic parameters. Several teeth analysis methods are proposed by analyzing and combining occlusal relationship and traditional orthodontic indices in orthodontic. Occlusal relationship, alignment and symmetry are then analyzed quantitatively. An occlusion assessment system is designed by combining measuring method of current orthodontic indices.The proposed assessment method has been validated by professional orthodontists that it is of high clinical application value.