Comparison of Mesiodistal Width of Maxillary Anteriors with Arch Form in Various Malocclusions: A Retrospective Study

INTRODUCTION

Younger generation nowadays is very concerned about their appearance, attractiveness, and beauty. Face plays a key role in attractiveness of an individual.¹ People perceive beauty by the size, arrangement, and appearance of anterior teeth in an individual.² The term “tooth size” refers to the mesiodistal width of the tooth. Tooth size and tooth arrangement vary among different individuals and different populations. Orthodontic literature has also supported the point that the tooth size and arrangement show a significant relation between genetic and environmental factors.³ Heredity, diseases, abnormal or premature birth, developmental defects, bone growth and tooth eruption pattern, environmental influences, function, and ethnic background have a great influence on the size and shape of dental arches.^4–6 Tooth size measurement is performed by using manual or digital method. Plaster models are used to visualize the shape and form of the arches and are also used for measuring the tooth size, as well as to provide the three-dimensional model of the patient’s occlusion.

It is observed that pattern of the supporting bone, perioral musculature force, and intraoral functional forces take part in the arch formation.⁷

Dental arch morphology has been described through different techniques starting from simple classification of arch shape⁸ by combination of linear dimension^9,10 to compound mathematical equations.^11,12 In 1932, the arch form concept was introduced by Chuck as square, ovoid, and tapered forms.¹³ Three types of arch forms can also be identified as narrow, normal, and wide clinically. Many researchers tried to identify the different shapes of the arch form with different malocclusions. The different malocclusions (classes I, II, and III) may also be the reason for changes in the relation to maxillary arch form and differences in its dimension.

This study was considered essential as it provides information regarding the relation of mean mesiodistal width of upper anteriors to Angle’s malocclusions and various arch forms.

This study was aimed to calculate the mean mesiodistal width of the maxillary anterior teeth and to evaluate its relation with the different malocclusions and arch forms.

MATERIALS AND METHODS

RESULTS

After calculating the mesiodistal width of 60 samples, the least obtained mesiodistal width was 40 mm, while the highest was 57 mm; so, the difference between these two values was calculated to be 17 mm. The three groups, namely 40 to 45.6 mm, 46 to 51.3 mm, and 52 to 57 mm, were formulated by dividing the 17-mm difference equally.

The mean value of maxillary anterior was compared among the three groups of malocclusions using the one-way analysis of variance (ANOVA) test. Mesiodistal widths of maxillary anteriors in class I, class II, and class III were compared. The results were found to be significant. A p value of ≤0.05 was considered statistically significant (Table 2A).

In class I group, the mean was found to be 50.43 mm. In class II group, the mean was found to be 49.96 mm. In class III group, the mean was found to be 45.15 mm. The p value was 0.0000, which was found to be statistically significant. Post hoc Bonferroni test was also done to confirm the results of ANOVA (Table 2A and Fig. 1).

The distribution of arch form was compared among various malocclusion groups (classes I, II, and III) using the Chi-square test. The p value was 0.003, which was found to be statistically significant (Fig. 2 and Table 2B).

The mode of arch form was compared on the basis of mesiodistal width of the anteriors in the three groups. Samples had more ovoid arch form with 40 to 45.6 mm anterior mesiodistal width and 46 to 57 mm anterior mesiodistal width existed with tapered arch form. In 46 to 57 mm anterior mesiodistal width, the ovoid arch form was second most found. The square arch form was least in all the three groups (Fig. 3 and Table 2C).

DISCUSSION

Mesiodistal tooth width, arch form, and growth pattern have an anthropological significance. These have revealed important information about individuals’ dietary habits and family lineage. Arch form, arch type, and teeth size are also much desired by forensic odontology experts while solving criminal cases.

This study provides important information regarding the mesiodistal width of maxillary anterior teeth and maxillary arch form with different malocclusions. Regarding class I malocclusion, the mean mesiodistal width was calculated to be 50.43 mm, which was correlating with the ovoid arch form. The tapered arch form was the common type in both class II and class III malocclusions with a mean mesiodistal width of 49.96 and 45.15 mm, respectively.

The result of this study also showed the relation of anterior tooth size of the upper arch in different malocclusions with different arch forms by using 3M Unitek arch form template. The outcome revealed that the sum of the anterior mesiodistal tooth size of maxilla if present below the 45.7 mm showed a relation with the ovoid arch form, while the value more than 45.8 to 57 mm was in a relation with the tapered arch form in different malocclusions.

In a study, Lavelle et al. concluded that class III individuals had remarkably smaller upper teeth than other groups.⁴ Our study also showed that class III malocclusion had a remarkably lesser mesiodistal width of anterior teeth than other groups.

The result of this study showed disagreement with Nie and Lin,¹⁴ Araujo and Souki,¹⁵ and Fattahi,¹⁶ who suggested that there are statistical differences in tooth size ratios among various groups. They reported that subjects with class III malocclusion always present with greater tooth size.

This study revealed that ovoid was the common arch form in class I and tapered was the followed arch form, whereas in class II groups, the most common arch form was tapered. These findings indicate that orthodontist should consider the ovoid arch form while treating class I, and for class II, tapered arch form wire should be selected.

This study was also supported by Murshid.¹⁰

This study showed that for class III samples, the arrangement pattern square form was more when compared with the three groups. The findings of this study were supported by Kook et al.¹⁷

Data from this study revealed that there is a relation between arch form and various malocclusions. The most stable arch form has been ovoid because it was seen maximum in class I cases. Hence, while ending up a class II or class III case, the final arch form for the patient should be ovoid, as it is the most stable retentive arch form. Also, this study can be used by forensic teams while inspecting decayed dead bodies to evaluate the type of arch form and type of malocclusion of the deceased by obtaining the MD width of the upper anteriors.

Although age and gender were taken as the inclusion criteria for the sampling, this study does not provide any comparison or relation data between age and gender of the subjects studied. This study was solemnly carried out to relate the arch form and mesiodistal width of maxillary anterior teeth with the malocclusion.

FUTURE SCOPE

Such studies should be carried out in different ethnic groups and population samples. The sample size should be increased, with gender specification and age specifications to obtain more significant results. Dental anomalies in tooth size, number, or shape and habit of the individuals should also be taken into measurement along with the mesiodistal and buccolingual proportion. The intra and interexaminer calibration should be developed to provide more reliable results. A digital intraoral scanner can be used to obtain the accurate arch form in all the malocclusion groups with gender specification.

CONCLUSION

The mean of anterior mesiodistal width for Angle’s class III individuals was considerably less than that of class II subjects and class I subjects, which signifies that the tooth material was more in the anterior region of the subject of class I followed by class II and class III malocclusions. The frequency of ovoid arch form was common among class I samples, while tapered was the common arch form in class II and class III individuals.

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