When indicating extraction of third molars, dentists should have a justifiable reason, one that takes into account future treatment planning from an orthodontic, surgical, periodontal, and/or prosthetic point of view . At the same time, a cost/benefit analysis should be carried out to justify the prophylactic removal of third molars, which should only be indicated with the purpose of preventing cases that involve pathological processes such as root resorption or caries in the second molar, cysts, and pericoronaritis [3, 4, 14, 15].
The most relevant finding of this study was the inability of orthodontists and OMFSs to predict third molar prognosis when these teeth erupted spontaneously. Indication was given in 37.8 % of cases by orthodontists and in 49.58 % of cases by OMFSs. These findings corroborate indication by other authors [16, 17] who—in the absence of reliable predictors—suggested that ideally third molars should be monitored through periodic evaluations. The risk of developing diseases was the key motivator leading orthodontists and OMFs to indicate third molar extractions in our findings. This concept seems to be adopted in several countries [6, 16, 17]. General dentists in the USA recommend removal of third molars in 59 % of cases . A comparative analysis between the opinion of orthodontists and OMFSs, as regards to the role of third molars, found that 56.9 % of OMFSs “often” or “sometimes” recommend prophylactic removal of third molars, while 64.4 % of orthodontists “rarely” or “never” make this recommendation, underscoring a significant disagreement between these two specialists . In this study, although both professionals showed significant agreement in their opinions (Kappa = 0.76), OMFSs tended to recommend more extractions than orthodontists (p < 0.0001). These findings support that orthodontists are more conservative than OMFSs and general dentists.
A survey comparing the views of clinicians and surgeons about the prophylactic removal of third molars conducted in Wales and Sweden found in the latter country a higher rate of third molar removal . The authors explained the results by stating that in Wales, a protocol was developed which provides guidelines to decide whether or not to extract third molars, whereas such protocol is not widely accepted in Sweden. Arguably, the large number of third molar extractions currently performed is due to the lack of a protocol containing criteria that should be examined prior to recommending extraction. Despite the fact that the agreement for the responses given by the two groups of specialists was remarkable, the large number of extraction indications shows that the criteria used to support this decision must be reviewed.
An improvement in third molar position is observed in patients treated with premolar extractions [18–22]; however, when third molars are excessively tipped, they may remain impacted even if there is enough retromolar space . If the probability of spontaneous eruption of third molars increases when premolars are extracted, it is likely that the reliability of prognosis is worse when these cases are assessed by orthodontists and surgeons. Thus, it seems necessary to evaluate the ability of the clinician to predict third molar eruption when orthodontic treatment involves premolar extractions.
Scientific evidence has shown that positional changes and eruption of lower third molar are unpredictable phenomena, whether in children and adolescents [8, 23] or even young adults . Mandibular third molars at, or near to, the the occlusal plane and exhibiting vertical inclination were considered at highest risk for developing pericoronitis. Such third molars can be given high priority for prophylactic care due to the possibility of severe consequences of acute pericoronitis . Furthermore, a higher incidence of dentigerous cysts may be associated with radiographically normal impacted lower third molar teeth . Thus, prophylactic extractions of normal impacted lower third molars can be a treatment option even considering the risk of TMJ disorders . The retrospective nature of this study increases the possibility of bias. A prospective follow-up study including different impaction severity and treatment outcomes should be considered, not only on an orthodontic perspective but also examining surgical complications after third molar removal .