A literature review study published in Oral Surgery, Oral Medicine, Oral Pathology, Oral Radiology, and Endodontology (August 2005;100(2):133-137) by Richardson and Dodson applied evidence-based principles to assess the risk of having periodontal defects on the distal aspect of the mandibular second molar (M2) following third molar (M3) removal. The study reviewed prospective cohort studies or randomized clinical trials with follow-up periods of 6 months or more, and preoperative and postoperative measurements of periodontal probing depths (PDs) or attachment levels (ALs). The review found that the reported mean changes in ALs or PDs on the distal of M2 6 months after M3 removal were clinically insignificant (< 2 mm). Six months after M3 removal, 52% to 100% of subjects had no change or improvement in ALs or PDs. Given periodontal disease present preoperatively, the number needed to treat (NNT) ranged from 3 to 10. Given healthy periodontal status preoperatively, 48% had worsening of their periodontal measures after M3 removal, and the number needed to harm (NNH) was 2.
The study concluded that commonly, the second molar periodontal probing depth or attachment levels either remain unchanged or improve after third molar removal. For subjects with healthy second molar periodontium preoperatively, the indication for third molar removal needs to be evaluated carefully as these subjects have an increased risk for worsening of probing depths or attachment levels after third molar removal.
(Source: National Institute of Dental and Craniofacial Research Web site, accessed August 3, 2005)
