Association of positional variations of premolars with interarch features among Malaysians

Objectives: This study aims to determine the prevalence of various premolar positions and to identify the interach features that are associated with these variations. Materials and Methods: Using a cross-sectional epidemiological study design, individuals meeting the selection criteria were randomly selected from the 15-35 years old Malaysian population. Dental impressions of 1000 subjects were obtained using alginate and poured into dental casts. Clinical data of the premolar positions and interarch features were made using these dental casts. Chi-square tests were performed to compare the prevalence rates among the positional variations of premolars. Results: A total of 4000 maxillary and 4000 mandibular premolar (N=8000) positions were observed in 1000 patients. Normal position accounted for majority of the premolars (59%), followed by those that were rotated (32.4%), displaced (6.9%), impacted (1.2%), unerupted (0.3%) and congenitally missing (0.2%). The left mandibular first premolars positions were mostly significantly associated (P<0.05) with all of the interarch features variables measured. Associations were noted with incisor relationships (p=0.004, Table 4), canine relationships (p=0.011, Table 5), molar relationships (P=0.043, Table 6), overjet (p=0.016, Table 7) and overbite (p=0.046, Table 8). Conclusion: The variations of premolar position shows significant association with interarch features; incisor, canine and molar classifications, as well as overjet and overbite.