Retained third molars not linked to second-molar loss in males, Finds study

The prophylactic removal of asymptomatic third molars is a common but controversial procedure often rationalized as necessary to prevent future disease on adjacent teeth.

E. Kaye and colleagues from the Department of Health Policy and Health Services Research, Boston University Henry M. Goldman School of Dental Medicine, Boston, MA, USA carried out the present study with the objective to examine whether second-molar loss differed by baseline status of the adjacent third molar, taking into account the individual's overall state of oral hygiene, caries, and periodontitis.

The authors analyzed data from participants of the VA Dental Longitudinal Study who had at least 1 second molar present at baseline and 2 or more triennial dental examinations. They classified second molars by third-molar status in the same quadrant: unerupted, erupted, or absent.

Tooth loss and alveolar bone loss were confirmed radiographically. Caries and restorations, calculus, and probing depth were assessed on each tooth. They further estimated the hazards of second-molar loss with proportional hazards regression models for correlated data, controlling for age, smoking, education, absence of the first molar, and whole-mouth indices of calculus, caries, and periodontitis.

The study revealed the following observations-

1. The analysis included 966 men and 3024 second molar/first molar pairs.
2. Follow-up was 22 ± 11 y (median 24, range 3–38 y).
3. At baseline, 163 third molars were unerupted, 990 were erupted, and 1871 were absent.
4. The prevalence of periodontitis on the second molars did not differ by third-molar status.
5. The prevalence of distal caries was highest on the second molars adjacent to the erupted third molars and lowest on the second molars adjacent to the unerupted third molars.
6. Relative to the absent third molars, adjusted hazards of loss of second molars were not significantly increased for those adjacent to erupted (hazard ratio [HR] = 0.96, 95% confidence interval [CI] = 0.79–1.16) or unerupted (HR = 1.25, 95% CI = 0.91–1.73) third molars.
7. Similar results when using alveolar bone loss as the periodontitis indicator were found.

Hence, the authors concluded that "retained third molars are not associated with an increased risk of second-molar loss in adult men."