Radiological Infrabony Defects After Impacted Mandibular Third Molar Extractions in Young Adults

Purpose To estimate the prevalence of infrabony defects and their healing at the distal aspect of mandibular second molars (M2s) after extraction of impacted mandibular third molars (M3s). Materials and Methods This prospective clinical study included 22 young healthy patients (21.03 ± 4.51 yr old). Thirty-seven surgical extractions of high-risk periodontal and mesioangular impacted M3s in close contact with adjacent M2s were performed. Radiographic bone height (RBH), radiographic infrabony defects (RIDs), and bone loss (BL) were recorded at baseline and 3, 6, and 12 months after surgery. RBH and RIDs were measured from the tip of a periodontal gauge to the root apex and to the cementoenamel junction of the M2, respectively; BL was calculated by dividing the length of the M2 root into thirds and categorized as slight, moderate, or severe. Results Only 26 extracted teeth were included in all radiographic assessments. Mean RID size at baseline was 4.54 ± 1.87 mm. At 12 months, an average recovery of 2.80 ± 2.36 mm ( P < .001) was recorded, for a mean RID size of 1.78 ± 1.65 mm. Statistically significant differences in RBH and RIDs were found at all assessments ( P < .05). Improved bone healing was registered during the postoperative period, with higher values during the first 3 months (1.3 mm; P < .01). Most RIDs of at least 4 mm associated with moderate or slight BL decreased to no larger than 3 mm without BL. For moderate BL, the bone gain pattern was gradual and continuous, whereas for slight BL, the pattern was variable. Conclusions In young healthy patients, a high-risk periodontal impacted M3 leads to an RID of at least 4 mm associated with slight or moderate BL at the distal aspect of the M2, which decreases to no larger than 3 mm 12 months after surgery. Bone healing is clinically and statistically significant at 12 months, with the most notable changes at the first 3-month follow-up.