Patterns of third-molar agenesis in an orthodontic patient population with different skeletal malocclusions

Abstract

Objective: To examine the relationship between third-molar agenesis and different skeletal malocclusion patterns. Materials and Methods: Pretreatment records of 1046 orthodontic patients (aged 13-17 years; mean age, 14.07 6 1.27) were used. Third-molar agenesis was calculated with respect to genders, number of missing teeth, jaws, and skeletal malocclusion patterns. The Pearson chi-square test was performed to determine potential differences. Results: Among the 1046 subjects, 237 subjects were diagnosed with third-molar agenesis (22.7%) with no statistical gender difference (P . .05). It was more common in the maxilla than in the mandible or in both jaws (P , .01). The prevalence of patients with a third-molar agenesis was the most commonly found type (P , .001). The prevalence of third-molar agenesis in those with a Class III malocclusion was significantly higher than in those with Class I or Class II (P , .05). However, there was similar prevalence among the hyper-divergent (24.5%), normal (23.8%), and hypodivergent (19.2%) groups (P . .05). Conclusion: These results suggest that agenesis of the third molar does not depend on vertical patterns of the skeletal malocclusions, but does depend on sagittal skeletal malocclusions in this orthodontic patient population. (Angle Orthod. 2012;82:165-169.)

Skeletal Facial Morphology and Third Molar Agenesis

“…The 2 studies that investigated the association of third molar agenesis, and the vertical skeletal dimensions display conflicting results. Celikoglu and Kamak (2012) reported that agenesis of the third molar does not depend on vertical patterns of the skeletal malocclusions (6). There was similar prevalence rate of third molar agenesis among the hyper-divergent (24.5%), normal (23.8%), and hypodivergent (19.2%) groups.…”

“…Third molar hypodontia seems to follow a similar pattern. It was shown that third molar agenesis was seen less in patients with skeletal Class II, and was most common in Class III skeletal relationship (6,16). Celikoglu and Kamak (2012) reported that the prevalence of third molar agenesis in those with a Class III malocclusion (28.4%) was significantly higher than in those with Class I (20.3%), and Class II (19.9%) malocclusion (6).…”

Pattern of Third Molar Agenesis among Patients with Different Skeletal Malocclusion

“…21,22 Furthermore, we observed higher frequency of M3 agenesis in maxilla (61.5%) compared to mandible (11.5%) which is similar to the study by Celikoglu and Kamak, 9 Kazanci, 3 Afzal et al 20 and Mok & Ho. 7 In addition, there was a significant difference in the occurrence of M3 agenesis between upper and lower jaw (p=0.001).…”

“…Few studies showed that hypodontia patients have higher tendency towards skeletal Class III pattern 23,24 followed by Class I. 9 This study also found the similar results with skeletal Class III patients having highest occurrence of M3 agenesis followed by skeletal Class I. In consistent with the study done by Celikoglu et al, 25 present study showed that the skeletal Class II malocclusion were less affected by M3 agenesis compared to other groups.…”

“…(46.2%) followed by one (34.6%), four (11.5%) and three M3s (7.7%), which is similar to the studies done by Banks 9 and Afzal et al 20 In Contrast, other studies found the order of frequency of M3 agenesis to be one, two, three and four respectively. 21,22 Furthermore, we observed higher frequency of M3 agenesis in maxilla (61.5%) compared to mandible (11.5%) which is similar to the study by Celikoglu and Kamak, 9 Kazanci, 3 Afzal et al 20 and Mok & Ho.…”