[The extraction of the lower third molars: germectomy or late avulsion?]

Abstract

Introduction: Lower third molars show the highest incidence of impaction and have been held responsible for pathologies such as pericoronitis, periodontitis, second molars tooth-crown resorption, pain, cysts or odontogenic tumors, primary or secondary crowding of the dentition. Early removal of these teeth to prevent the overmentioned problems is widely acknowledged, as many studies demonstrated a direct correlation between age and incidence of complications. These studies mostly refer to adult patients, while studies about germectomies are few. Because recent contributions showed that the risk of development of these pathologies in presence of impacted third molars is quite low while a certain morbidity associated to this procedure may be expected, a very careful risk to benefit ratio must be considered. The purpose of this study was therefore to compare the incidence of complications and side effects in three age groups, in order to obtain some informations about the choice of the best moment for operation.

Materials and methods: The patients, 462 females and 406 males, were divided, according to age, in the following three groups: group A included patients from 9 to 16 years; group B included patients from 17 to 24 years; group C included patients over 24 years. All patients were treated under local anesthesia; surgical procedure and instruments were standardized.

Results: In group A, formed by 500 germectomies, the incidence of complications was 2.6% (10 instances of secondary infections, 2 instances of trismus, 1 instance of excessive postoperative bleeding). Group B included 570 procedures and the incidence of complications was 2.8% (3 instances of alveolar osteitis, 7 instances of secondary infections, 2 instances of excessive postoperative bleeding, 2 instances od second molar lesions, 1 instance of inferior alveolar nerve paresthesia, 1 instance of trismus). Group C included 430 procedures and the incidence of complications was 7.4% (2 instances of second molar lesions, 9 instances of alveolar osteitis, 8 instances of secondary infections, 4 instances of excessive postoperative bleeding, 6 instances of inferior alveolar nerve paresthesia, 3 instances of trismus). All complications were transient; in one instance only of mandibular nerve paresthesia in group C symptoms were still present 25 months after the operation.

Discussion and conclusions: This study has shown no significant differences between group A and B, while complications significantly increase in group C. Recent researches have shown that: a) there is a low risk of development of pathologies correlated to third molar impaction; b) nowadays there are not valid criteria to evaluate the future eruption of the impacted tooth; c) a direct correlation between third molar impaction and anterior dental crowding hasn't been demonstrated yet; d) morbidity of the procedure is relevant. Therefore germectomy should be performed: a) if morphostructural alterations or ectopic impactions are present; b) in case eruption is not allowed for dysplastic alterations of the germs or pathological processes of the mandible; c) to gain space in the posterior segments of the lower jaw when distalization of first and second molars is necessary; d) in case of excessive anterior-posterior mandibular growth.