Surgical extraction of impacted mandibular third molars is one of the most frequently performed procedures in oral and maxillofacial surgery.1 Despite being routine, the procedure is often associated with postoperative complications such as pain, swelling, trismus, and delayed periodontal healing of the adjacent second molar. Among these, periodontal breakdown distal to the mandibular second molar remains a major concern due to its long-term implications on oral health.2 Flap design plays a crucial role in surgical access, visibility, wound closure, and healing. The commonly used flap designs for mandibular third molar surgery include envelope flap and triangular (three-cornered) flap.3 While the triangular flap provides improved surgical access, it involves a vertical releasing incision which may compromise blood supply and increase postoperative inflammation. Conversely, the envelope flap preserves vascularity but may limit access in deeply impacted teeth.4

Periodontal healing following third molar surgery depends on several factors including patient age, oral hygiene, impaction depth, bone removal, and surgical technique. Improper flap design may lead to increased probing depths, attachment loss, and periodontal pocket formation distal to the second molar, ultimately predisposing the area to chronic periodontal disease.5 Several studies have investigated the influence of flap design on postoperative outcomes; however, conflicting results exist regarding which design offers superior periodontal healing.6,7 Some authors suggest envelope flaps minimize periodontal damage, while others report no significant difference between flap types.8

Given the clinical importance of preserving periodontal health adjacent to the second molar, the present study aimed to evaluate and compare the effect of envelope and triangular flap designs on periodontal healing after surgical extraction of impacted mandibular third molars.

This comparative clinical study was carried out in the Department of Oral and Maxillofacial Surgery over a period of 12 months. A total of 120 systemically healthy patients aged between 18 and 35 years requiring surgical extraction of impacted mandibular third molars were included after obtaining ethical approval from the institution wide number (ERC-W1Y56). Patients with pre-existing periodontal disease, pericoronitis, smoking habits, or systemic conditions affecting wound healing were excluded.

Patients were randomly allocated into two equal groups. Group A underwent surgical extraction using an envelope flap, while Group B underwent extraction using a triangular flap. All procedures were performed by the same surgeon under local anesthesia following standardized surgical protocols. Bone removal and tooth sectioning were carried out where necessary. Primary closure was achieved using 3-0 silk sutures.

Periodontal parameters of the mandibular second molar adjacent to the surgical site were recorded by a blinded examiner. Probing depth, clinical attachment level, plaque index, and gingival index were measured preoperatively and postoperatively at 1 week, 1 month, and 3 months. Postoperative medications and oral hygiene instructions were standardized for all patients.

Data were analyzed using statistical software. Descriptive statistics were calculated, and intergroup comparisons were made using independent t-tests. A p-value of <0.05 was considered statistically significant.

Table 1 demonstrates that both groups were comparable in terms of age and gender distribution. No statistically significant difference was observed between Group A and Group B with respect to baseline demographic characteristics, indicating adequate randomization and group homogeneity.

Table 1: Demographic Distribution of Study Participants

Table 2 shows a postoperative increase in probing depth at one week in both groups, reflecting immediate surgical trauma. However, a progressive reduction in probing depth was observed over time, with Group A exhibiting significantly lower values at one month and three months compared to Group B, indicating better periodontal healing with the envelope flap design.

Table 2: Mean Probing Depth (mm) of Adjacent Second Molar

Table 3 highlights that patients in Group A had significantly less clinical attachment loss compared to Group B at the three-month follow-up. Additionally, a higher percentage of patients in the triangular flap group demonstrated attachment loss greater than 3 mm, suggesting an increased risk of periodontal compromise associated with this flap design. Group A demonstrated significantly better periodontal outcomes with reduced probing depth, attachment loss, plaque accumulation, and gingival inflammation at all postoperative intervals.

Table 3: Clinical Attachment Loss at 3 Months

The present study evaluated the influence of flap design on periodontal healing distal to the mandibular second molar following surgical extraction of impacted third molars. The findings revealed that although both flap designs resulted in acceptable healing, the envelope flap demonstrated superior periodontal outcomes compared to the triangular flap.

The increased probing depth observed during the first postoperative week in both groups can be attributed to surgical trauma, edema, and inflammation.9 However, a more pronounced increase in probing depth was observed in the triangular flap group, possibly due to the presence of a vertical releasing incision which may disrupt vascular supply and delay healing.10 At the three-month follow-up, Group A showed significantly lower probing depth and attachment loss. This finding is consistent with previous studies that reported better periodontal healing with envelope flaps due to minimal tissue trauma and preservation of blood supply. Studies by Singh et al. (2022)11 and Albanese et al. (2023)12 also reported reduced periodontal pocket formation with envelope flap designs.

In contrast, some authors have reported no significant difference between flap designs. However, these discrepancies may be due to variations in sample size, surgical skill, follow-up duration, and oral hygiene compliance. In the present study, strict standardization of surgical technique and postoperative care may have contributed to clearer outcome differences. The higher plaque and gingival index scores observed in the triangular flap group may be related to delayed soft tissue healing and increased patient discomfort, leading to compromised oral hygiene in the early postoperative period.13 From a clinical perspective, preserving periodontal health of the second molar is critical, especially in young patients where long-term tooth retention is desired.14 The results of this study suggest that envelope flap design offers a more favorable environment for periodontal healing.

Envelope flap design demonstrated better periodontal healing compared to triangular flap following surgical extraction of impacted mandibular third molars. Selection of flap design should prioritize preservation of periodontal health of the adjacent second molar.

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