An interesting study titled “What is the Risk of Future Extraction of Asymptomatic Third Molars? A Systematic Review,” written by Gary F. Bouloux and et al., appears in the May 2015 issue of the Journal of Oral and Maxilofacial Surgery (vol. 73, issue 5). The study attempts to determine the annual and cumulative rate of when asymptomatic wisdom teeth become necessary to remove.
The authors state that the management of asymptomatic wisdom teeth is controversial and unresolved. They performed a systematic review of past studies using PubMed, Google Scholar, and the Cochrane Central Register of Controlled Trials on retained wisdom teeth. The authors had several criteria necessary for the study to be included in their analysis. The studies were included if they were an English language publication, were a prospective study design, had more than 50 subjects, had recorded the number of subjects or wisdom teeth requiring extraction during the study period, and had a follow-up duration of 1 year or more. Additional criteria were patients aged 18 years old or older, at least 1 wisdom teeth present at enrollment, and only asymptomatic wisdom teeth at enrollment.
The authors started with 65 studies and narrowed it down to 7 studies for analysis. They state
“To estimate the cumulative incidence rate of [wisdom teeth] removal, the number of [wisdom teeth] (or subjects) removed during the follow-up period was divided by the total number of [wisdom teeth] (or subjects). The annual incidence rate was estimated by dividing the cumulative incidence rate by the total number of follow-up years.”
The authors found the cumulative incidence for wisdom teeth extraction varied from 5% at 1 year to 64% at 18 years and was associated with the follow-up duration. The annual incidence rate for wisdom teeth extraction varied from 1 to 9%, with a mean of 3.0% annually. The studies reported data that limited what the authors could do in their analysis.
“The point at which the [wisdom teeth] were extracted during the studies was not reported. This prevented calculation of the variation in the rate of extraction over time using a life table analysis, which would have provided a better understanding of the age-related changes in the frequency of [wisdom teeth] extractions.”
The authors discuss in their discussion that with a 3% annual risk of extraction of wisdom teeth it may be a more prudent strategy to remove asymptomatic wisdom teeth at a younger age in addition to those with caries, periodontal disease, pericoronitis, or other pathologic features. The authors also note that in the 7 studies they used in their analysis it is possible some of the wisdom teeth extracted were asymptomatic and disease free which could have lead to an overestimation in their calculation of the cumulative annual risk of wisdom teeth removal.