Relationship between skeletal malocclusion and dental anomalies in Nepalese population

Introduction: Teeth eruption is important for the development of alveolar process which increases vertical height of the face and third molar is the last tooth to erupt in the oral cavity after birth. The aim of this study was to determine relationship between skeletal malocclusion and dental anomalies in Nepalese population. Materials & Method: A sample of 170 patients with agenesis of at least one third molar was divided into four groups according to the third-molar agenesis pattern. Panoramic radiographs, lateral cephalograph and cast models were used to determine the skeletal malocclusion and associated dental anomalies. The Pearson chi-square test was used for stastical analysis. Result: Among 170 patients more than half of the patients were female with the average age being 18.15 ± 3.64 years. Majority of the patients had Class I skeletal malocclusion followed by Class II and III but on group wise comparison of patients with different skeletal patterns Class I skeletal malocclusion had highest prevalence of dental anomalies followed by Class III and Class II malocclusion. Conclusion: Prevalence of third-molar agenesis was more in skeletal class I malocclusion followed by class II and III but skeletal Class I malocclusions had more dental anomalies followed by class III and class II malocclusion.


INTRODUCTION
Tooth agenesis is the congenital absence of at least one permanent tooth, because it never formed. 1 The order of decreasing frequency of agenesis is third molar, mandibular second premolar, and maxillary lateral incisor, suggesting that it is the most distal tooth in each group that disappears. 2,3 Ageneses do not appear in isolation, 4 they are usually associated morphology, and its varying presence or absence in the oral cavity. 7 Variations in tooth morphology are associated with tooth agenesis, including reduced mesiodistal crown diameter and conical or tapered crowns. 8 Corresponding contralateral teeth are often accompanied by imperfect morphologic formation. 9 The alveolar process, the portions of the mandible and the maxilla that surround and support the dentition, dependent on crown completion and root formation. 10 Third molars are important in assessing the dental age of juveniles and also provide forensic specimens. 4,11 Orthodontic treatment planning is also affected by third molar agenesis, especially when arch distalization is planned.

MATERIALS AND METHOD
The subjects for the study were selected from

RESULT
Among 170 patients more than half of the patients were female. Majority of the patients had Class I skeletal malocclusion followed by Class II and III ( Table   2). The results showed that Class I skeletal malocclusion had highest prevalence of dental anomalies followed by Class III and Class II malocclusion (Table 3). This difference in proportion among the patients reached statistical significance with p value less than 0.001.
Thus, there is a significant association between skeletal malocclusion and occurrence of dental anomalies.
The results are summarized in tables 1, 2, 3 and 4.
Pant BD, Rajbhandari A, Pradhan R, Bajracharya M, Mishra S, Gharti B : Relationship between skeletal malocclusion and dental anomalies in Nepalese population

DISCUSSION
Third molar is a tooth that develops after birth and also the last tooth to erupt. It is characterized by the variability in the time of its formation, its widely varying crown and root morphology, and its varying presence or absence in the oral cavity. 7 The purpose of this study was to determine the association between skeletal malocclusion and dental anomalies in Nepalese population. One hundred seventy sample of adolescent patients aged between 13 to 25 years with agenesis of at least one third molar was selected from the files of orthodontic patients undergoing treatment in Department of Orthodontics, Peoples dental college and hospital, Kathmandu, Nepal.
In this study minimum age was set at 13 years because third molar crypt formation starts at 3 to 4 years of age, calcification begins from 7 to 10 years, crown calcification completes at 12 to 16 years of age and eruption occurs between 17 to 25 years of age. 12,13 Upper age limit was set at 25 years because upto this Prevalence of third-molar agenesis was more in skeletal class I malocclusion followed by class II and III which was not in accordance with Celikoglu, 6 who reported that the prevelance of third molar agenesis was more in skeletal class III followed by class I and II, this may be due to polygenetic inheritance on formation of third molar germs that control maxillary and/or mandibular dimensions which was different in different Pant BD, Rajbhandari A, Pradhan R, Bajracharya M, Mishra S, Gharti B : Relationship between skeletal malocclusion and dental anomalies in Nepalese population   population. Present study also shows that skeletal Class I malocclusions had more dental anomalies followed by class III and class II malocclusion which was stastically significant.

CONCLUSION
Prevalence of third-molar agenesis was more in skeletal class I malocclusion followed by class II and III but skeletal Class I malocclusions had more dental anomalies followed by class III and class II malocclusion. OJN