Analysis of the distance between lingual frenal attachment and mandibular incisal edge position in establishing occlusal plane in three different races

INTRODUCTION: The orientation of the occlusal plane forms the basis for the arrangement of teeth conducive to satisfactory esthetics and function, making it one of the most important clinical procedures in prosthodontic rehabilitation. This study aimed to analyze and compare the vertical distance between the anterior attachment of lingual frenum (AALF) and the incisal edge of mandibular central incisors among three races in Malaysia.

MATERIALS AND METHODS: The sample consisted of 63 dentate subjects (21 Malays, 21 Chinese, and 21 Indians) who were chosen based on the inclusion criteria. Two models were made using irreversible hydrocolloid impressions, and an average of the value was obtained. Lingual frenum was recorded in function. Casts were fabricated with dental stone. AALF was marked and the vertical distance was measured using a caliper.

RESULTS: In Malays, the mean and standard deviation of the vertical distance were 14.2 ± 0.9 mm, with a range of 12.3-16.0 mm; in Chinese were 14.4 ± 0.9 mm, with a range of 12.0-16.9 mm; and in Indians were 15.1 ± 1.0 mm, with a range of 13.0-17.2 mm. The difference among the three races regarding the distance between AALF and the incisal edge of mandibular central incisors was statistically significant (P < 0.05). Among the three races, Malays and Indians have the greatest mean difference.

CONCLUSION: According to the results of the current study, the distance between AALF and the incisal edge of mandibular central incisors might be a proper criterion for the initial adjustment of occlusal rims. The values obtained from three different races were significantly different from one another, hence a different range of values was used to establish occlusal height for different races.