Effect of Eruption Status of the Mandibular Wisdom Teeth on Distal Caries in the Adjacent Second Molar

An article titled “Effect of Eruption Status of the Mandibular Third Molar on Distal Caries in the Adjacent Second Molar,” written by Feiwu Kang and et. al. appears in  the 2016 issue of J Oral Maxillofac Surg. The article explores the eruption of mandibular wisdom teeth and their effect on adjacent second molars. A total of 500 cone beam computed tomography (CBCT) images of mandibular third molar (MTMs) from 469 patients were evaluated. The authors assessed the presence of distal caries in mandibular second molars (MSMs), impaction depths and angulations of MTMs, cementoenamel junction (CEJ) distances between distal MSMs and mesial MTMs, presence of pericoronitis in MTMs, and patient characteristics (age and gender). The authors state that previous studies show the prevalence of distal caries in MSMs has ranged from 13.4 to 30.1%.

The authors found that the overall prevalence of distal caries in the mandibular second molars was 52.0%. According to the classification of Pell and Gregory, position A was the impaction depth at which most distal caries in MSMs were present (P= .036). For angulation of the mandibular third molars, when mesial angulations were 43 to 73%, MSMs developed more distal caries (P < .0001).

Previous studies have reported that the prevalence of distal caries in MSMs increases with age. In study, patients 27 to 59 years old were 2.18 times as likely to have distal caries in MSMs as those 16 to 27 years old. Further, in the study, gender did not influence the presence of distal caries in the MSM. The study focused mainly on the effects of eruption status of the MTM on distal caries in the adjacent MSM because previous studies have indicated that susceptibility to distal caries in MSMs is linked to the presence of MTMs instead of oral hygiene.

The authors found 1) prophylactic removal of MTMs should be considered when the MTM exhibits an angulation of 43 to 73% or a position A impaction depth; 2) angulation of the MTM is more stable and reliable than the CEJ distance between the distal MSM and the mesial MTM in the estimation of risk factors related to the MTM; and 3) patients older than 27 years should pay close attention to their asymptomatic third molars.

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