Prevalence of Hypodontia in Unilateral and Bilateral Cleft Lip and Palate Patients Inside and Outside Cleft Area: A Case-Control Study.

Objectives: The aim of this study is to evaluate the prevalence and distribution of hypodontia, inside and outside the cleft area, in an Italian population with a non-syndromic unilateral (UCLP) and bilateral (BCLP) cleft lip and palate on panoramic radiographs and comparing it with a control sample.

Study Design: Case group was ethnically uniform and consisted in 233 patients. The control group was composed of 1000 subjects. Patients included were between seven and fifteen years old. Descriptive analysis, using absolute and relative frequencies, was performed to check out the prevalence of gender distribution, hypodontia and cleft formation. Statistical analysis was conducted with Chi-squared test, Yate's correction and the Fisher's exact test. The power was set higher than 0.8 for each test.

Results: 160 cleft patients (68.68%) presented at least one missing tooth, while 88 patients in the control groups presented agenesis (8.80%). A statistically significant difference was found in case and control groups for upper lateral incisors (37.34% and 48.07% in the case group against 2.50% and 2.60% in the control group), upper and lower second premolars (8.58%, 6.44%, 5.58% and 6.01% in the cleft group and 0.60%, 0.60%, 2.50% and 2.70% in the control group).

Conclusion: Higher prevalence of dental agenesis in the maxillary dental arch is explained by the cleft defect. Higher prevalence of mandibular second premolars agenesis cannot be explained by the anatomical defect and suggests a multifactorial aetiology, including environmental and genetic factors, of the cleft condition.