Fingernail form as a post-extraction guide for selecting the maxillary central incisor tooth form in the Saudi Arabian population: A novel application of CAD software.

Background: Human teeth and nails have demonstrated similar factors genetically, embryologically, and morphologically. The fingernail form may be used as a post-extraction guide for selecting the tooth form. Aim: To evaluate the correlation between the maxillary left central incisor tooth form with the left index, middle, and ring fingernails in the Saudi Arabian population. Materials and Methods: A descriptive cross-sectional study with purposive sampling was done among 200 Saudi participants. The maxillary left central incisor and the left index, middle, and ring fingernail were scanned using an intraoral scanner. The 3D digital images were converted to 3D models. The tooth form (tooth length, tooth width, and tooth shape) and nail form (nail length, nail width, and nail shape) were measured using the CAD software. Pearson's correlation coefficient and T-test were used for statistical analysis (P < 0.05). Result: A significant correlation exists between tooth length and nail length, with a maximum correlation toward index nail length (P = 0.015). A significant correlation exists between tooth width and nail width, with a maximum correlation toward ring nail width (P = 0.002). A significant correlation exists between tooth length and nail length in females with a maximum correlation toward index nail length in females (P = 0.001). The mean percentage of similarity between tooth and nail shape (index, middle, and ring) in males and females shows a highly significant difference between them (P = 0.001). The results indicate that the tooth and nail shape are similar (70 to 90%) based on the criteria set by the software. Conclusion: A definite correlation exists between maxillary central incisor tooth form and fingernail form. The fingernail form may be used as a post-extraction guide for selecting the maxillary central incisor tooth form in the Saudi Arabian population.

A comparative study on the influence of third point of reference on condylar guidance settings in a semi-adjustable articulator with lateral cephalographs: An in-vivo study.

AIM: The study aimed to evaluate the effect on condylar guidance values with casts mounted by facebow transfer (Guichet's point as the third point of reference), Bonwill's, and radiographic method. MATERIALS AND METHODS: The dentulous subject's casts were mounted to a semi-adjustable articulator (Artex Type AR) after facebow transfer with Guichet's point as the third point of reference and also by Bonwill's method. Protrusive records made earlier were utilized to program the right and left side condylar guidance value. Two digital lateral cephalograms were made, one in centric relation, and one in protrusion and the condyles were traced and overlapped. The condylar guidance readings obtained by Bonwill's method, facebow transfer, and lateral cephalometric tracings were compared in this study using the SPSS (Version 17.0 Illinois, Chicago, USA) software. RESULTS: The condylar guidance values obtained from Bonwill's and the facebow transfer method (p < 0.001) was lesser than the radiographic method. The values obtained by casts mounted to the Bonwill's method differed significantly (p < 0.001) from the other two methods. CONCLUSION: The values obtained by facebow transfer were closer to the radiographic values whereas the values obtained by Bonwill's method mounting differed markedly.