Age and third molar extraction as risk factors for TMD

Objective: Third molar removal has been identified as a risk factor for TMD in teenagers and young adults. The current study utilizes dental and medical claims data to investigate this potential relationship among all age groups. Methods: The subjects were selected from enrollees of Kaiser Permanente Northwest (KPNW), a large HMO providing both dental and medical coverage, who had 6 years of continuous coverage (Jan. 1998 - Dec. 2003). The final sample consisted of 2217 KPNW enrollees with a history of third molar extraction during the study period, and 2217 age and gender-matched enrollees with radiographic confirmation of no lifetime third molar removal.  Exposure information (eg, tooth number, severity of impaction, etc) was obtained from electronic dental claims data, and medical ICD-9 codes were used to identity TMD outcomes.  Relative risks were calculated to assess the impact of third molar extraction on subsequent TMD for the entire sample, as well as by each decade of life. Gender, extraction parameters (type of anesthesia, provider, arch of extraction, and severity of impaction), and time since exposure were also assessed. Results: The table below lists relative risks overall, by age category, gender, severity of impaction, and years after exposure. Conclusions: This study is suggestive of an increased risk in those younger than 20, as well as in subjects with more severely impacted teeth. There was a significantly increased risk for TMD in the first year after third molar removal.  This study supported by NIDCR grant DE14609-01.