[Evaluation of correlation between vertical dimension of occlusion [VDO] and facial proportions]

Establishment of VDO [Vertical Dimension of Occlusion] is one of the most important factors in prosthetic rehabilitation of edentulous patients. There is no universally accepted method in VDO determination for edentulous patients. The aim of this study was to evaluate the relationship between VDO and facial proportions. In this descriptive analytical cross-sectional study, sixty four 20-30 year old dental students with class I occlusion were selected. The distances between subnasal to submental areas in the maximum intercuspation, external corner of the eye to corner of the mouth, first one third eyebrows to the ala of the nose and outer corner of one eye to the inner corner of the other eye were measured. Two methods of measurement were used: 1] electronic digital caliber to measure the indices on the face. 2] Auto CAD software to measure the indices on the subjects' digital photos. Pearson and linear regressions tests were used for statistical analysis. The results showed a significant correlation between VDO and measured indices [p<0.001]. There was no significant difference between the two methods. A minimal correlation was detected between VDO and the outer corner of one eye- the inner corner of the other eye dimension. A significant correlation was found between VDO and the external corner of the eye- corner of the mouth distance. It is concluded that some guidelines can be used for VDO determination. The vertical distance between the external corners of the eye to the corner of the mouth was the most reliable guidelines

[Evaluation of the relationship between the shape of the face and the shape of the maxillary central incisors in 18 to 25 year old students]

The shape of a patient face is commonly used as a reference to select the shape of the maxillary central incisors in edentulous patients. The validity of this relationship has not been proved. The objective of this clinical study was to determine whether a relationship exists between maxillary central incisor and face shape. In this descriptive analytical study two standard digital photographs of 186 students were made, one full face and the other from two maxillary central incisor's computer software named PhotoShop [7.0] was used for assessing correlation between tooth and face formed by superimposition. A visual analysis was made to determine the extent of correlation. In addition, the overall shape of the face and teeth was classified in ovoid, square, tapered, square-tapered and tapered- square groups and compared to gather. Statistical analysis was performed using chi-square and Fisher's Exact tests. The comparison of the face shapes with the reverse out line forms of left and right maxillary central incisors showed that 24% of cases had unsimilar faces and tooth forms, 51% had similar face and tooth firms and only 25% had correspond state. Women produced a better match than men 44% of subjects had the same tooth and face forms but for 56% of subjects, they were different. In this study correspondence between face and tooth forms occurred in one forth of cases. As a conclusion, no significant relationship existed between the face shapes and the inverted tooth forms