An interesting article titled “How Many Patients Have Third Molars and How Many Have One or More Asymptomatic, Disease-Free Third Molars?” appears in the September 2012, supplement 1. (vol. 70, issue 9) of the Journal of Oral and Maxillofacial Surgery written by Thomas B. Dodson, DMD, MPH (pg. S4-S7). The article seems to attempt to arrive at an answer to the question of how many patients really have a wisdom tooth (third molar) that is not causing problems and that has no disease.
In the article Dr. Dodson recommends that patients are divided into 4 different categories when having their wisdom teeth evaluated.
- symptomatic, disease present (based on history and radiological examination)
- symptomatic, disease absent (includes teething and vague pain symptoms unrelated to wisdom tooth)
- asymptomatic, disease present (disease is evident from radiological findings or clinical exam but not patient complaints)
- asymptomatic, disease absent
In the article over 20 journal articles are assessed to determine how many patients have wisdom teeth of which a number ranging between 6.0% to 96% is arrived at. The range is so broad due to differences in assessments and definitions. Several articles are briefly described which attempt to show third molar prevalence. These articles sometimes include if the wisdom tooth is erupted or not and the overall prevalence.
The author includes his definition of what a asymptomatic disease free third molar is on clinical examination
“On clinical examination, a disease-free impacted [third molar] will not be visible, cannot be probed, and probing depths (PDs) will be shallower than 4 mm. If the tooth is erupting, there must be adequate space to accommodate the tooth. A disease-free erupted tooth will have reached the occlusal plane, be functional and hygienic, and have PDs shallower than 4 mm. The tooth will be caries-free, or have restorable caries, or be well restored. All 5 surfaces of the tooth can be examined for caries. The tooth will be surrounded by attached gingiva, including the distal aspect of the tooth.”
With regards to radiological examination, no evidence of disease is present. The author is clear to say that the absence of symptoms does not equal the absence of disease. The author later describes two different studies which an estimate of disease free asymptomatic wisdom teeth can be obtained from.
The first study consisted of 409 asymptomatic volunteers. 119 (29%) of the patients in the study were also free of disease (according to the definition provided above). The second study consisted of 249 patients of which 29 (11.6%) had all asymptomatic disease free third molars with a total of 855 wisdom teeth (37.3%) being asymptomatic and disease free.
The author states in the conclusion:
“The differences between the 2 estimates may be due to differences in the sample composition (patient vs volunteer samples), sites of referral (hospital vs school or clinic), definitions of disease status, and eligibility…”
Based on the literature review and the 2 studies the article concludes that patients with disease free asymptomatic wisdom teeth represent a small proportion of patients. In this study, of course some may take issue with the definition of what an asymptomatic disease free third molar is. Furthermore, some may take issue of the difference between a patient with all asymptomatic disease free third molars and some (1 or more but not all) asymptomatic disease free third molars. Naturally it would be the case that encountering a patient with all asymptomatic disease free third molars would occur less likely than encountering a patient with one or more asymptomatic disease free third molars.
When a patient has some asymptomatic disease free wisdom teeth present but also either asymptomatic or symptomatic with disease present wisdom teeth, the issue of whether to extract them all or retain some can be hazy. For example see the case report described under mouth sinus hole in the wisdom teeth complications page http://www.teethremoval.com/complications.html.