# Evaluation of the Distal Periodontal Bone Defect Associated with Lower Third Molar Extraction  
[PERSON]  
1 Department of Surgery, Medicine, Dentistry and Morphological Sciences with Transplant Surgery, Oncology and Reggio Emilia, 41125 Modena, Italy; [EMAIL_ADDRESS] (P.B)  
1 Department of Surgery, Medicine, Dentistry and Morphological Sciences with Transplant Surgery, Oncology and Reggio Emilia, 41125 Modena, Italy; [EMAIL_ADDRESS] (P.  
is associated with complications like pericoronitis, dental caries, and cystic lesion, making third molar extraction a routine procedure for Oral and Maxillofacial surgeons [6; 7; 8]. The impaction angle, representing the angle formed between the longitudinal axes of the second and third molars, is commonly classified using [PERSON]'s classification system [7]. Both maxillary and mandibular third molars, whether impacted or not, can be classified using the [PERSON] and Gregory classification system [5]. The eruption of third molars frequently presents periodontal challenges for adjacent second molars, with studies identifying a link between third molar presence and periodontal defects. The decision to extract an impacted tooth requires a thorough assessment of alternatives. Factors influencing this decision include the depth of impaction, proximity to vital structures, patient age, systemic conditions, and compliance. Comprehensive clinical and radiological evaluations are for informed decision-making. Proper preoperative planning, supported by operator experience, minimizes unforeseen complications. Orthopantomography (OPG) is the preferred imaging method for initial evaluation, offering a panoramic view of dental arches and adjacent structures (Figure 1). OPG combines low-radiation exposure with patient comfort. Computed tomography (CT) with specialized software may provide three-dimensional analyses for more complex  
[PERSON] et al. suggest that the third molars should be extracted before the age of 25 in at-risk patients, as older age reduces the likelihood of complete recovery [11; 12; 13; 14]. Younger patients demonstrate better bone healing and fewer complications, especially when root apex maturation is incomplete [15; 16]. A history of periodontitis, deep pockets, and older age are recognized as independent risk factors for residual pockets \(\geq\) 4 mm [9]. Regarding surgical technique, [PERSON] & [PERSON] [15] suggest that flap design has minimal influence on bone loss distal to the second molar but may reduce residual distal pocket depth. Authors like [PERSON] and [PERSON] et al. [16] propose that the choice of flap design should favor maintaining periodontal health distal to the seventh molar. A 2023 systematic review suggests that a three-sided flap may slightly outperform an envelope flap in reducing Probing Pocket Depth (PPD) after six months, with baseline PPD being the strongest predictor of post-operative outcomes [17; 18]. Impaction type and initial periodontal status also influence periodontal healing [18]. Factors such as the contact area between the second and third molars, their close proximity, and the inclination of the second molar are correlated with bone and periodontal healing post-extraction. According to [PERSON] et al. [19], three major risk factors for residual periodontal defects in the second molar are the presence of preoperative crestal radiolucency visible on panoramic radiography, the level of impaction, and the presence of postoperative plaque. Preoperative radiolucency as a predictor of residual bone defect was previously reported by [PERSON] (1991b) [12], and [PERSON]'s [19] study confirms this association. The mesioangular inclination of the third molar inevitably creates a space between the second and third  
Figure 2: Cone beam CT scan of impacted third molar in different sections. molars, promoting subgingival microbiota colonization, including periodontaltopathogen bacteria [20]. Recent studies further elucidate these phenomena. [PERSON] et al.