Determination of Familial Inheritance of Temporomandibular Joint Disorders Among the Urhobos in Delta State, Nigeria

This study determined if temporomandibular joint disorders (TMDs) are substantially heritable among the Urhobos in Delta State, Nigeria. Ethical clearance was sought from the Research and Ethics Committee of the Delta State University Teaching Hospital, Oghara, Delta State. Multistage sampling was used in this study to select 384 Urhobo subjects. A total of 96 families (96 fathers, 96 mothers and 192 offsprings) were examined. Data collection was done between the first day of the month of February and the last day of the month of July in the year 2025. The subjects were examined physically and completed questionnaire regarding age, gender, ethnicity, social status, personal and medical history, antidepresant drug usage, dental status, limited mouth opening, temporomandibular joint sound and parafunction (bruxism, clenching). Examination of the temporomandibular joint was guided by the principles based on International RDC/TMD and the amendments thereto (version: 20 Jan 2014). Data obtained was subjected to Statistical Package for the Social Sciences (SPSS), version 24.0. Results were presented in frequency distribution and cross tabulation. All inferential statistical analysis was carried out at 95% confidence level, with P<0.05 regarded as significant. Mendelian chi-square analysis was done to determine the closeness of the observed offspring outcome (TMDs) to the expected Mendelian ratio. The results divulged that gender variation in prevalence of TMDs among the Urhobo subjects is not significant. Mendelian chi square test when both parents are affected by TMDs disclosed a chi square value of 0.000. This indicates exteme closeness of the observed offspring outcome (TMDs) to the expected Mendelian ratio. The p-value is greater than the chosen significance level (0.05), thus the null hypothesis should be accepted. Accepting the null hypothesis after the Mendelian chi-square test means that the observed results (TMDs) are statistically close enough to the expected Mendelian ratios. The conclusion is that the TMD data supports the predicted inheritance pattern (3:1 or 9:3:3:1 ratio) and does not show a statistically significant deviation from it. This means the results are consistent with Mendelian inheritance. Thus the present scrutiny affirms that temporomandibular joint disorders are substantially heritable among the Urhobos in Delta State, Nigeria.