Impaction of third molars is commonly encountered as demonstrated by various studies [2–4]. Caries and periodontal diseases are commonly seen in relation to the impacted third molars and are often the reason for their extraction. Surgical removal of impacted third molar is one of the commonest procedures. It demands sound knowledge of surgical principles in-order to minimize the trauma and the postoperative complications. Different techniques have been described to perform atraumatic extraction and reduce the post-operative complications. Pain, swelling and trismus are the most frequently reported side effects of mandibular third molar surgery.[6] This study was carried out in Nepal to investigate the role of two most commonly used flap designs, envelope and triangular, effect on the postoperative outcomes.
As reported by several studies [7–10, 13, 15, 17–28] flap design may have a role in the postoperative outcome in the third molar surgery. An envelope flap design with a sulcular incision from the first to second molar and a distal relieving incision to the mandibular ramus is commonly employed. The surgical site is generously uncovered, ensuring a good overview during surgery. The sulcular incision can be prolonged mesially any time as required. As a consequence of the extensively prepared mucoperiosteal flap, osseous defect can always be safely covered after the removal of the molar. Moreover, a large flap with a broad base guarantees a good vascularity up to the wound margins. Possible disadvantages of this method are also discussed. Every mucoperiosteal flap leads to a growing activity of osteoclasts in the area of the alveolar process, including loss of alveolar bone. Every sulcular incision is an intervention to the periodontal ligament and may lead to periodontal damage [12].
Triangular flap is similar in the first part of the incision to the envelope flap design. However, it differs by a vertical incision is continued from the distobuccal line angle of the second molar apically, extending to the mucogingival line about 2-3mm. Therefore, the second molar is involved only upto the distobuccal edge, thereby restricting more involvement of the periodontal tissues. It is simple to close and allows for relatively tension free closure. However unlike the envelope flap, it cannot be readily extended [8].
The present study compared the postoperative outcomes of two most commonly used flap design employed in the removal of impacted 3rd molar. The results regarding the swelling comparison between the two flap designs showed greater swelling in the triangular flap than the envelope flap and it was statistically significant in postoperative measurement on day 2. The overall mean result showed less swelling using the envelope flap on all 2nd, 7th, 14th postoperative days but it was only significant on 2nd postoperative day. This is also consistent with the reposts of other studies such as Baqain et al., Kirk et al., Alqahtani et al., Ergogan et al., Korkmaz et al., Desai et al and Alqahtani et al. who also observed greater postoperative swelling in the triangular flap design than the envelope flap [6, 13, 29–32]. In recent MRI study by Jeong- Kui Ku et al. also favored the envelope flap design over triangular flap in respect to swelling [33].
The probable explanation to the increased in swelling noticed in the triangular flap design could be attributed the anterior releasing incision which introduces a greater inflammatory response and the resultant edema in the buccal tissues. However, in other studies carried by Dolanmaz et al, Monaco et al. and Koyuncu et al. no statistically significant difference between the two flap designs were found regarding the postoperative swelling [10, 26, 34].
Regarding the evaluation of pain score using visual analog scale (VAS) both the flap designs showed similar result and difference between the two on all three measurements of postoperative day 2, day 7, and day 14 were statistically insignificant. This is consistent with other studies conducted by Baqain et al., Mobilio et al., Dolanmaz et al., Kirk et al., Monaco et al., and Enrico et al. [6, 9, 10, 13, 34, 35] where no statistically significant result was found comparing the two flap designs. However, in other study comparing the two flap designs, Sandhu et al. found less postoperative pain using the triangular flap [11]. Similar study by Koyuncu et al. found less postoperative pain using the triangular flap design [26]. Similar findings with less postoperative pain was found by Rabi et al. in their study [23]. In other studies, conducted by Erdogan et al., Korkmaz et al., and Mohajerani et al., they found less pain score using the envelope flap [29–31].
Regarding the postoperative trismus it was measured by comparing the maximum mouth opening in millimeters before and after the surgery on postoperative 2nd, 7th and 14th day. The envelope flap yielded better result comparing with the triangular flap but it was statistically significant only on postoperative day 14th. Baqain et al. found a similar result where the triangular flap design resulted in a significantly greater reduction in maximum inter incisal mouth opening and this was observed on postoperative days 7th and 14th [6] Similar result with better mouth opening in the envelope flap design was found by Enrico et al. in 2014 [35]. In a study by Sandhu et al. they found better result using the bayonet flap(triangular) comparing with the envelope flap though it was statistically insignificant [11]. Similar result favoring the triangular flap over envelope flap was found by Rabi et al on the evaluation of mouth opening postoperatively though statistically insignificant [23]. Mobilio et al. found out no significant difference between the two flap designs for any postoperative symptoms and signs. The duration of surgery was found to be correlated to both trismus and swelling as assessed 2 days after third molar removal. No association was found on the 7th postoperative interval [9]. Similar result with no significant difference between the two flap designs was found by Erdogan er al., Kirk et al. [13, 30].
Alveolar osteitis was reported in 3 cases in each flap designs whereas wound infection was not reported in either group.
Within the limitations of the study, it can be concluded that, when swelling and trismus were considered the envelope flap design yielded better result compared to the triangular flap, whereas pain score was similar in both the flap designs.
LIMITATIONS
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Some patients did not follow the post-operative instructions that were given.
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Degree of trauma to hard and soft tissue during the removal of impacted 3rd molar may vary.
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Since the study was done in a small sample from a single center, it cannot be taken as strong model.