Research and Education
Maxillary lateral incisor agenesis and its relationship to overall tooth size

This article is based on the Master’s thesis (J.W.) presented in 2011 in partial fulfilment of requirements for the degree of Master of Science, Marquette University School of Dentistry, 2011.
https://doi.org/10.1016/j.prosdent.2015.07.010Get rights and content

Abstract

Statement of problem

Agenesis of the maxillary lateral incisor has been linked to differences in the size of the remaining teeth. Thus, the mesiodistal space required for definitive esthetic restoration in patients with missing maxillary lateral incisors may be reduced.

Purpose

The purpose of this study was to determine whether a tooth size discrepancy exists in orthodontic patients with agenesis of one or both maxillary lateral incisors.

Material and methods

Forty sets of dental casts from orthodontic patients (19 men and 21 women; mean 15.9 years of age; all of European origin) were collected. All casts had agenesis of one or both maxillary lateral incisors. Teeth were measured with a digital caliper at their greatest mesiodistal width and then compared with those of a control group matched for ethnicity, age, and sex. Four-factor ANOVA with repeated measures of 2 factors was used for statistical analysis (α=.05).

Results

Orthodontic patients with agenesis of one or both maxillary lateral incisors exhibited smaller than normal tooth size compared with the control group. The maxillary arch had a larger tooth size difference between the control and test groups than the mandibular arch (there was a significant Jaw×Group interaction [F=4.78, P=.032]).

Conclusions

Agenesis of one or both maxillary lateral incisors is significantly associated with tooth size discrepancy, which may affect the space remaining for restoration of the remaining teeth.

Section snippets

Material and Methods

This research was approved by the Institutional Review Board. Forty sets of dental casts (21 women, 19 men, mean 15.9 years of age), with missing maxillary lateral incisors (22 unilateral, 18 bilateral) (Fig. 1), were collected from local orthodontic practices. For comparison, an equal number of dental casts were collected from the Graduate Orthodontics program at the Marquette University School of Dentistry to form a control group matched for ethnicity, age, and sex. Inclusion criteria for the

Results

The results of this study reject the null hypothesis that no differences exist in tooth size in patients with agenesis. Orthodontic patients with agenesis of one or both maxillary lateral incisors exhibited smaller than normal tooth size than the control group. (F=4.01, P=.049) (Table 2; Fig. 3A).

Men were found to have larger teeth than women. (Table 2; Fig. 3B). Canine teeth presented the largest tooth size differences between men and women (there was a significant tooth type×sex interaction

Discussion

Although clinicians discuss the minimum necessary space for an implant when one or both maxillary lateral incisors are missing, they should focus on determining the appropriate space for the implant/restoration. The golden proportion for the anterior teeth can be considered when they determine the size for the missing lateral incisor.3 Patients with smaller than normal maxillary and mandibular teeth, as shown in the test sample of this study, may require a smaller than necessary 6.5-mm or 7-mm

Conclusions

Orthodontic patients with unilateral or bilateral agenesis of the maxillary lateral incisor have smaller than average teeth when compared with a control-matched group. The maxillary arch has larger tooth size differences between the control and test groups than the mandibular arch. Clinicians should consider the findings of this study when preparing maxillary lateral incisor sites for restorations.

Acknowledgments

The authors thank Drs William Lobb, Gerard T. Bradley, and Dawei Liu, Marquette University School of Dentistry, for advice and suggestions; and Jessica Pruszynski and Dr Raphael Benoliel for statistical analysis.

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      Therefore, our first and third hypotheses were partially accepted, and the second hypothesis was fully accepted. Few authors have evaluated the relationship between the congenital defects of maxillary lateral incisors (agenesis or size discrepancy) and the mesiodistal widths of other teeth.18-20,27,28 However, these studies had some limitations that may prevent clinicians from drawing conclusions about certain clinical situations.

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    Supported, in part, by the American Association of Orthodontists and American Association of Orthodontists Foundation (to J.A.B.).

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