Radiographic Evaluation of the Margin Distance of Class II Restorations to the Bone Crest (Biologic Width Invasion)

Background: It has been established that biologic width (BW) is essential for maintaining periodontal health and alleviating irritations that may harm the periodontium. Thus, biologic invasion should be evaluated, especially after restorative treatment. This study aimed to radiographically examine the distance from the margin of Class II restorations to the bone crest in maxillary and mandibular premolars and molars. Methods: Bitewing images of 64 patients (218 teeth) with Class II restorations were collected from oral and maxillofacial imaging centers in Bandar Abbas during 12 months. The data were analyzed using SPSS 22 and Scanora 5.0.2. Results: The results revealed that 90 (41.3%) out of the total 218 teeth were premolars, and the remaining 128 teeth (58.7%) were molars. Approximately 45.68% of the examined teeth showed violations of the biologic width. Moreover, 93 teeth (42.7%) were mesial, and 125 teeth (57.3%) were distal. Further, biologic width invasion was more prevalent on the distal surfaces of teeth than on mesial surfaces. Based on the results, 88 teeth (40.4%) had overhangs. Eventually, 65 teeth (29.9%) undergoing root canal treatment (RCT) had BW invasion, while 35 teeth (16.1%) that did not undergo RCT violated BW. Conclusion: The restoration of molar teeth led to violations of BW more frequently than that of premolars. Violations on BW were more prevalent in teeth that had undergone RCT. The incidence of violation into the BW was greater on the distal surfaces of teeth compared to the mesial surfaces.