Dr. Friedman is correct that pathology associated with 2nd molars adjacent to erupted and partially erupted 3rd molars is well known (Garaas et al., 2011; Falci et al., 2012; Friedman, 2014). Our article sought to categorically define the risk posed to adjacent 2nd molars by unerupted, erupted, or absent 3rd molars (Nunn et al., 2013). Previously, the most comprehensive study was The Third Molar Clinical Trials (White, 2007). However, these included only patients with 4 retained asymptomatic 3rd molars and adjacent 2nd molars. Our study included participants with any retained asymptomatic 3rd molars and adjacent 2nd molars and also those with absent 3rd molars. Inclusion of these additional categories allowed for comparison of bony-impacted, soft-tissue–impacted, erupted, and absent 3rd molars on the risk of 2nd molar pathology, which is a novel contribution of our study.
Dr. Friedman is also correct about the low prevalence of soft-tissue–impacted 3rd molars in our study cohort. Nevertheless, the associated absolute risks for 2nd molar tooth loss and 2nd molar pathology are substantial (Table). Importantly, we found that bony-impacted 3rd molars posed no more risk to adjacent 2nd molars than did erupted 3rd molars. This information may be useful in guiding decision-making by patients with various types of unerupted 3rd molars. Analysis of our data clearly indicates that any potential benefit to 2nd molars of prophylactic removal of 3rd molars is related to the type of 3rd molar status. Last, our findings should not be inferred as justifying the prophylactic removal of asymptomatic 3rd molars. Rather, these findings are consistent with the approach of ‘watchful waiting’.
Table.
Absolute Risk over Course of Study
| 3rd Molar Status | 2nd Molar Loss (entire study) | 2nd Molar Pathology (entire study) |
|---|---|---|
| Absent | 0.0% | 39.6% |
| Erupted | 3.8% | 52.8% |
| Soft-tissue impaction | 39.1% | 81.6% |
| Bony impaction | 14.6% | 56.5% |
Acknowledgments
The VA Dental Longitudinal Study and VA Normative Aging Study are components of the Massachusetts Veterans Epidemiology Research and Information Center, supported by the US Department of Veterans Affairs Cooperative Studies Program. Dr. Garcia was a recipient of a VA Career Development Award in Health Services Research from the VA HSR&D Service.
Footnotes
This work was also supported by NIDCR grants K24 DE000419 and R01 DE019656. Views expressed in this paper are solely those of the authors and do not necessarily represent the views of the US Department of Veterans Affairs.
The authors declare no potential conflicts of interest with respect to the authorship and/or publication of this article.
References
- Falci SG, de Castro CR, Santos RC, de Souza Lima LD, Ramos-Jorge ML, Botelho AM, et al. (2012). Association between the presence of a partially erupted mandibular third molar and the existence of caries in the distal of the second molars. Int J Oral Maxillofac Surg 41:1270-1274. [DOI] [PubMed] [Google Scholar]
- Friedman J. (2014). Letter to the Editor, “Retained asymptomatic third molars and risk for second molar pathology.” J Dent Res 93: (in press). [DOI] [PubMed] [Google Scholar]
- Garaas R, Moss KL, Fisher EL, Wilson G, Offenbacher S, Beck JD, et al. (2011). Prevalence of visible third molars with caries experience or periodontal pathology in middle-aged and older Americans. J Oral Maxillofac Surg 69:463-470. [DOI] [PubMed] [Google Scholar]
- Nunn ME, Fish MD, Garcia RI, Kaye EK, Figueroa R, Gohel A, et al. (2013). Retained asymptomatic third molars and risk for second molar pathology. J Dent Res 92:1095-1099. [DOI] [PMC free article] [PubMed] [Google Scholar]
- White RP., Jr (2007). Progress report on Third Molar Clinical Trials. J Oral Maxillofac Surg 65:377-383. [DOI] [PubMed] [Google Scholar]