Incisive Papilla as a Biometric Reference to Maxillary Anterior Tooth Positions Among Kenyans of African Descent

Abstract

Introduction: Denture aesthetics is key in patient satisfaction with complete denture treatment. Positions of maxillary anterior teeth are critical in the aesthetic outcome of complete dentures. Positions of denture teeth are best determined using pre-extraction records, but most persons who seek complete denture construction in Kenya do not have these records. Biometric guides have been used to determine positions of prosthetic teeth, the most common one being the incisive papilla. This study sought to describe the relationship between the incisive papilla and the maxillary anterior teeth among Kenyans of African descent. Aim: To describe the relationship between the incisive papilla and the positions of the maxillary anterior teeth among Kenyans of African descent. Materials and Methods: Maxillary impressions were taken of 112 participants from the College of Health Sciences (CHS) of the University of Nairobi (UoN) using irreversible hydrocolloid and generated in Type IV gypsum. The canine tips and the posterior limit of the incisive papilla were marked on each cast. Photocopies of the casts were taken at 1:1 ratio. On the photocopies a line was drawn to connect the canine tips. Lines through the posterior limit of the incisive papilla and the most labial aspect of the right central incisor were drawn parallel to the inter-canine line. A perpendicular line was drawn connecting the three lines. The distance between the lines was measured in mm using a digital caliper. Each subject was instructed to stand upright and place his/her head in the physiologic natural head position looking at the horizon. With the head in this position, the relationship between two lines was noted; one line dropped from the bridge of the nose to the base of the upper lip and a second one extending downward to the chin. Facial profile was judged as straight if the three points were on a straight line, convex if the middle point (base of upper lip) was anterior to the two other points and concave when the middle point was posterior to the other two points. The somatotype was categorized by the investigator based on the general body build of the subject as ectomorphic (tall and thin), mesomorphic (average) and endomorphic (short and fat). Results: This study was conducted among students of CHS, UON aged 18-35 years. The most labial aspect of maxillary central incisor was a mean of 14.93±1.52mm from the posterior limit of the incisive papilla. This was statistically different from findings from Caucasian populations (p<0.001). This distance did not vary with the gender (t=0.52, p=0.61), facial profile (t=0.93, p=0.35), or body type (F=1.05, p=0.35). There was a weak correlation between this distance and the age (r= ‒0.178, p=0.061). The inter-canine line was a mean of 4.73±1.73mm anterior to the most posterior limit of the incisive papilla. This finding contradicts recommendations from Caucasian studies (t=28.93, df= 111, p<0.001). There was weak correlation between age and the distance from the posterior margin of the incisive papilla to the inter-canine line (r= -0.13, p= 0.15). There was no variation on the relationship between the inter-canine line and the posterior margin of the incisive papilla with gender (t=0.14, p=0.89), facial profile (F=0.17, p= 0.68), body type (F=0.51, p= 0.61). The distance between the posterior margin of the incisive papilla to the inter-canine line varied with the arch form (F=3.40, p= 0.04). The mean inter-canine width was 35.44±1.79mm. The inter-canine width was significantly higher among the males than the females (t=2.68, p=0.008). There was no variation in the inter-canine width with age (Pearson correlation=0.03, p=0.75), facial profile (t=0.17, p= 0.86) or body type (F=0.86, p=0.43). The inter-canine width for square arches was significantly higher than that of ovoid and tapering arches. There was a weak correlation between the inter-canine width and the distance from the inter-canine line to the most posterior limit of the incisive papilla (r=‒0.09, p=0.34).There was a correlation between the inter-canine width and the distance from the posterior limit of the incisive papilla to the most labial aspect of the right maxillary central incisor. The distance from the posterior limit of the incisive papilla to the inter-canine line was correlated to the distance from the posterior limit of the incisive papilla to the most labial aspect of the 11 (r=0.75, p< 0.05). Conclusion: The mean distance from the posterior margin of the incisive papilla to the most labial aspect of the maxillary central incisor was 14.93±1.52mm among Kenyans of African descent. This is different from findings among Caucasian populations. The mean distance from the posterior margin of the incisive papilla to the inter-canine line was 4.73±1.73mm. This finding contradicts the recommendation from Caucasian studies.