Is arch form influenced by sagittal molar relationship or Bolton tooth-size discrepancy?

A study to estimate tooth size discrepancy values specific to Saudi orthodontic patients: A systematic review and meta-analysis

Objective

This study aimed to establish intermaxillary tooth size ratios (overall index (OI) and anterior index (AI)) for normal occlusion and different Angle's malocclusions specific to the Saudi population and compare them to Bolton's values, which were specific to Americans.

Methods

The Saudi Digital Library, PubMed, Web of Science, Cochrane Library, Scopus, and Embase were searched systematically to acquire articles which reported OI and AI for Saudi patients; inclusion and exclusion criteria were applied. Data, including author's name, publication year, city, measurement technique, number of subjects, type of occlusion, means, and standard deviations, were extracted and sorted. To assess the methodological quality of the included studies, The National Heart, Lung, and Blood Institute Quality Assessment Tool for Observational Cohort and Cross-Sectional Studies was utilized.

Results

Of the 1473 articles, eight met the inclusion criteria and were included in the meta-analysis. Values for normal occlusion and Bolton's values were not significantly different. All malocclusion classes showed significant differences in the overall OI and AI values compared with Bolton's original values and values for normal occlusion, but they did not differ from each other. Gender showed an effect only on the OI ratio for Class III malocclusion.

Conclusions

Bolton's original values can be used in Saudi patients only with normal occlusion. For cases with any Angle's malocclusion, we recommend using an AI value of 79.08 (±3.4) for both genders. Classes I and II, regardless of gender, have the same OI value of 92.51 (±2.82). For Class III, values of 91.97 (±2.4) for females and 93.13 (±2.6) for males can be used.

Mandibular Clinical Arch Forms in Iraqi Population: A National Survey

Background: This study aims to identify mandibular clinical arch forms and dimensions in the Iraqi population. Materials and methods: The study sample consisted of pre-treatment mandibular study models of the Iraqi population. The most labial aspect of 13 proximal contact areas was digitized using AutoCAD software to determine the clinical bracket point for every tooth. The dental arches were classified into three types: tapered, ovoid, and square. The arch dimensions were identified using four linear and two proportional measurements. Results: A total of 1005 study models were collected. The arch forms were distributed as ovoid (47%), tapered (36.2%), and square (16.8%), with no significant difference in the distribution between Arabs and Kurds. The ovoid arch form was predominant in class I and class III malocclusion, while the tapered arch form was predominant in class II. All the linear measurements were greater in the males than in the females. The arch widths decreased as the arch form shifted from square to ovoid to tapered, while the arch depths showed the reverse relation. Conclusions: According to this study, ovoid and tapered archwires should suit the majority of Iraqi patients. The ovoid arch form was the most predominant in the subjects with class I and class III malocclusion, while the tapered arch form was the most predominant in the class II subjects.

The Tooth Size Discrepancy among Orthodontic Patients and Normal Occlusion Individuals from Saudi Arabia: A Three-Dimensional Scan Analysis of Diagnostic Casts

Background/Purpose:

Tooth size discrepancy is one of the causative factors of malocclusion. This study aimed to establish the TDS among various malocclusion classes and normal occlusion subjects in a Southern Saudi population.

Materials and Methods:

The study casts of orthodontic patients from Southern Saudi Arabia (mean age: 19.6 years ± 2.45; n = 120) were randomly selected and grouped into eight equal classes based on Angle's classification and gender. An additional 30 study casts, devoid of malocclusion, having excellent intercuspation and class I occlusion, were grouped into two controls (n = 15) based on gender. The study casts were three-dimensional scanned to measure mesiodistal widths of all the teeth. The calculated anterior ratios (AR) and overall ratio (OR) were statistically analyzed with analysis of variance and t-tests.

Results:

There were no significant differences in “OR” and “AR” between the genders (P > 0.05) and among the malocclusion and control subgroups (P > 0.05). The mean “OR” (92.01 ± 0.18) and “AR” (78.60 ± 0.27) of the malocclusion group were significantly higher than that of Bolton's ratios (P > 0.05). The “AR” of the control group was significantly higher than Bolton's standards (P = 0.048). However, “OR” was no different (P = 0.105). Malocclusion patients displayed a discrepancy (±2 standard deviation) in “AR” of 22.5% and 'OR' of 6.7% from Bolton's mean (BM). Similarly, the control group displayed a discrepancy in “AR” of 20% and “OR” of 10% from BM.

Conclusion:

The mean “OR” and “AR” of the Southern Saudi population showed no sexual dimorphism and no significant difference among various malocclusion and control subgroups. The “AR” of the malocclusion and control subgroups did not comply with Bolton's standards.