Are third molars a threat to periodontal health?

This summary is based on the article published in the Journal of Maxillofacial and Oral Surgery: Third molars: a threat to periodontal health? (June 2012) 

G. S. Kaveri and Shobha Prakash

Context

Third molars have received a fair amount of interest in literature. They have been blamed for problems, such as lower incisor crowding, atypical facial pain, caries etc. They are considered as ‘waste bins’ in dental practices as they are regarded as functionally non-essential. While making clinical decisions about treatment, third molars are given less importance and are often considered for extraction as the treatment option.

Despite periodontal problems that can arise with extracted third molars, retention of third molars can also lead to periodontal problems with the adjacent teeth in addition to teeth farther to third molars. Therefore, it has become very important to consider the periodontal problems while making clinical treatment decisions.

Purpose of the Review

To review the need for taking a more serious account of third molars and its relation to periodontal health.

Key Messages

1. It is not just the presence or absence of symptomatic or asymptomatic third molar that makes the decision difficult but sometimes the consequences that follow with either of it. One needs to consider the endodontic, prosthodontic, surgical, periodontic, orthodontic prognosis of third molar. It is this inter-disciplinary concern that makes the clinical decision difficult and needs to be totally weighed.
2. Caries and periodontal diseases occurring in relatively older age group were the major reasons for non-surgical extraction of third molars while recurrent pericoronitis occurring in relatively younger age was the major reason for surgical extraction of impacted third molars. (1) 
3. Justifications for prophylactic surgery include the need to minimize the risk of disease (cysts and tumors) development, reduction of the risk of mandibular angle fracture, increased difficulty of surgery with age, and that third molars have no definite role in the mouth. (2)
4. Those with a visible third molar are more likely to have greater periodontal probing depths overall, particularly on second molars, and a greater surface area of the biofilm-gingival interface compared with those with no visible third molar. (3)
5. The finding of more severe periodontal conditions associated with visible third molars in the young adults indicates that third molars may have a negative impact on periodontal health. (4)
6. Studies have concluded the incidence of deep periodontal pocket in second molar after removal of third molars. (5, 6, 7, 8)
7. There are also studies that reported improvement in periodontal conditions of second molar following the removal of third molar. (9, 10)
8. Third molar periodontal pathology appears to be a significant risk indicator for periodontal disease progression during pregnancy. (11)

References

1. http://www.oralhealthjournal.com/news/third-molar-surgery-areview- of-current-controversies-in-prophylactic-removal-ofwisdomteeth/1000330848/3-12-10 
2. Adeyemo WL (2006) Do pathologies associated with impacted lower third molars justify prophylactic removal? A critical review of the literature. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 102(4):448–452 Epub 2006 May 11.
3. White RP Jr, Fisher EL, Phillips C, Tucker M, Moss KL, Offenbacher S (2011) Visible third molars as risk indicator for increased periodontal probing depth. J Oral Maxillofac Surg 69(1):92–103 Epub 2010 Nov 2.
4. Elter JR, Cuomo CJ, Offenbacher S, White RP Jr. (2004) Third molars associated with periodontal pathology in the Third National Health and Nutrition Examination Survey. School of Dentistry, University of North Carolina, Chapel Hill, NC, USA.
5. Richardson DT, Dotson TB (2005) Risk of periodontal defects after third molar surgery: an exercise in evidence-based clinical decision making. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 100:133–137.
6. Ash M, Costich ER, Hayward R (1962) A study of periodontal hazards of third molars. J Periodontol 33:209–215.
7. 10. Chin Quee TA, Gosselin D, Millar EP, Stamm JW (1985) Surgical removal of the fully impacted mandibular third molar. The influence of flap design and alveolar bone height on the periodontal status of the second molar. J Periodontol 56:625–630.
8. Osborne W, Snyder A, Tempel T (1981) Attachment levels and crevicular depths at the distal of mandibular second molars following removal of adjacent third molars. J Periodontol 53:93–95.
9. Pecora G, Cellen R, Davapanah M, Covani U, Etienne D (1993) The effects of guided tissue regeneration on healing after impacted mandibular third molar surgery: 1-year results. Int J Periodon Restor Dent 13:397–407
10. 13. Grondahl HG, Lekholm U (1973) Influence of mandibular third molars on related supporting tissues. Int J Oral Maxillofac Surg 2:137–142.
11. Moss KL, Ruvo AT, Offenbacher S, Beck JD, Mauriello SM, White RP Jr (2007) Third molars and progression of periodontal pathology during pregnancy. J Oral Maxillofac Surg 65(6): 1065–1069.

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