Angular changes of impacted mandibular third molars and developing mandibular third molars in premolar extraction cases- A retrospective radiographic study

Abstract

Background: Successful eruption of impacted third molars requires the establishment of proper mesiodistal angulation as the tooth erupts into the oral cavity. Extraction of premolars in orthodontic cases may favour the eruption of third molars. Materials and Methods: Patients were divided into 2 categories. Category I -Radiographs of patients undergone orthodontic treatment with third molar roots formation completed and category II -Radiographs of patients undergone orthodontic treatment with third molar roots formation uncompleted. The samples consisted of 24 third molars in each category with a total of 48 samples. On pre operative and post operative OPGs linear and angular measurements were measured. Results: There was statistically significant difference in the space between the anterior border of the ramus and the second molar. But there was no significant difference in the angulation of the third molars. So even if there is a gain of space for the third molars to erupt, the changes in the angulations of third molar does not favour the spontaneous eruption after the orthodontic treatment with extraction of 1 s t premolar. Conclusion: Extraction of 1 s t premolar has positive influence on the space available for the third molar eruption. But there are no changes in the angulations of the third molars that would in turn help in the eruption.

Beyond the ARCH: Examining mandibular third molar movements in response to premolar and single incisor extractions in orthodontic practice

“…The inclusion criteria include Panoramic radiographs at T0 & T1 of patients with formulated treatment plan of extraction of premolars and single incisor. 5 The exclusion criteria include 1. Patients were excluded if the 3 r d molars at T0 had already erupted 2.…”

“…Additionally, the absence of periosteal growth on the maxillary tuberosity can also hinder the emerging of maxillary third molars. 4,5 due to natural attrition between neighbouring teeth which allowed for drifting of the posterior teeth, lack of proper uprightness during the process of root formation often results in third molar impaction, particularly more frequently in the lower jaw rather than the upper. 6 Third molars can appear on radiographs as early as 5 or as late as 16 years.…”