Overall and Anterior Tooth Size Ratios In A Group of Emiratis

Abstract

Aims: 1- To study overall and anterior tooth size ratios in a group of Emiratis with Class I normal occlusion. 2- To estimate overall and anterior tooth size ratios in different malocclusion groups of Emiratis. 3- To compare overall and anterior tooth size ratios of a group of Emiratis, with Class I normal occlusion, with the Bolton standards. 4- To determine the distribution of overall and anterior tooth size ratios ± 2 SD from Bolton mean values in all occlusion groups.

Materials and Methods: Consecutive patients’ files, including dental casts, were selected from the archives of the governmental orthodontic clinics of the Dubai Health Authority located in Bur Dubai and Bur Deira. The final sample was formed following the application of specific inclusion criteria: healthy patients, age from 13-18 years, Emirati origin, complete permanent dentition, in which, however, second and third molars may be absent, normal tooth crown morphology, no dental anomalies in tooth shape, tooth size and tooth number, no history of interproximal reduction, no restorations altering mesiodistal tooth crown width, complete record files and excellent quality of study models. The exclusion criteria were: history of systemic diseases, craniofacial anomalies, medical history contributory to dental and jaw development, mixed Emirati origin, mixed dentition, presence of dental anomalies in tooth shape, tooth size and tooth number, history of interproximal reduction, restorations altering mesiodistal tooth crown width, congenital missing teeth, incomplete record files and poor quality of study models. The sample consisted of 521 pairs of dental casts representing both sexes (males: 188; females: 333) and different occlusion groups (Class I malocclusion: 288; Class II malocclusion 110; Class malocclusion: 30; Class I normal occlusion: 93). The mean age of patients whose dental casts were utilized in this study was 16.18 years for Class I malocclusion, 15.73 years for Class II malocclusion, 15.83 years for Class III malocclusion and 16.55 years for Class I normal occlusion. The dental casts were selected, scanned using Ortho Insight 3D laser scanner (3D Motion View, Chattanooga, Tennessee, USA) and digitized by the author using the Ortho Insight 3D laser scanner (3D Motion View Software). Measurements were made regarding maxillary and mandibular sums of mesiodistal tooth dimension of the overall (6-6) and anterior (3-3) groups of teeth. In order to test the intra-examiner reliability, the author re-measured 50 pairs of casts, which were randomly selected from the original sample one week after the initial measurement. The intra-examiner reliability was assessed using paired t-test. Statistical analysis included descriptive statistics, paired t-test and analysis of variance (ANOVA). The level of significance was set at p<0.05.

Results: No statistically significant differences were found between the first and the second sets of measurements thus, confirming the intra-examiner reliability. The mean values of overall ratios were 91.57 for Class I malocclusion, 91.54 for Class II malocclusion, 90.21 for Class III malocclusion and 91.41 for Class I normal occlusion. In addition, the mean values of anterior ratios were 78.05 for Class I malocclusion, 79.14 for Class II malocclusion, 77.54 for Class III malocclusion and 77.54 Class I normal occlusion. There was a statistically significant difference among malocclusion groups. Comparison of overall and anterior tooth size ratios between the III sample of this investigation with Class I normal occlusion and the Bolton standards showed no statistically significant differences. Only five cases in Class II malocclusion presented an anterior tooth size discrepancy outside plus 2 SD from Bolton mean values and one case in Class I malocclusion presented with an overall tooth size discrepancy outside plus 2 SD from Bolton mean values.

Conclusions: Based on the finding of this investigation the following conclusions could be presented regarding the Emirati sample which was studied: - • Class I normal occlusion cases presented similar overall and anterior tooth size ratios to Bolton standards. • Overall and anterior tooth size ratios among occlusion and different malocclusion groups exhibited statistically significant differences. • Five cases in Class II malocclusion presented an anterior tooth size discrepancy outside plus 2 SD from Bolton mean values. • One case in Class I malocclusion presented with an overall tooth size discrepancy outside plus 2 SD from Bolton mean values.