Comparison of a new flap design with the routinely used triangular flap design in third molar surgery

Abstract

The aim of this study is to introduce a new flap design in the surgical removal of impacted mandibular third molars – a lingually based triangular flap – and to compare this flap design with the routinely used triangular flap. This randomized, prospective, split-mouth study involved 22 patients with impacted bilateral mandibular third molars that were symmetrically positioned, mesially angulated, and retained in bone. The impacted teeth were removed in two sessions, using two different flap designs: the new alternative flap and the traditional triangular flap. Postoperative complications (pain, swelling, trismus, alveolar osteitis, and wound dehiscence) were recorded on days 2, 7, 14, and 21. The data obtained were analysed using the χ 2 test, the Mann–Whitney U -test, and Pearson’s correlation. In terms of the severity of postoperative facial swelling and trismus, there were no statistically significant differences between the flap designs ( P > 0.05). The alternative flap exhibited higher pain scores at 12 h post-surgery ( P < 0.05). In addition, the alternative flap group exhibited less wound dehiscence, although this was not statistically significant. Moreover, all wound dehiscence in this group occurred on sound bone. In conclusion, these results show that this new flap design is preferable to the routinely used flap for impacted third molar surgery.

The mandibular third molars, or wisdom teeth, are present in 90% of the population, with 33% exhibiting at least one impacted third molar. Owing to the high incidence rate of impacted third molars, their surgical excision is probably the most frequently performed operation in oral and maxillofacial surgery. Morbidities associated with the surgical removal of an impacted third molar, such as pain, swelling, trismus, alveolar osteitis (dry socket), nerve damage, and compromised periodontal status of the adjacent second molar, still pose a major problem for surgeons and patients. Postoperative morbidity has important medical, legal, and economic implications. Consequently, many surgical approaches have been tried to minimize these complications, such as the use of surgical drains, different wound closure techniques, and various flap designs.

In oral surgical procedures, it is desirable to place the mucoperiosteal incision on sound bone. Many flap designs used in impacted third molar surgery do not follow this rule, as they involve incisions that are placed on the extraction socket, resulting in a high incidence of mucosal dehiscence, followed by secondary wound healing. In secondary healing, the buccal flap is often tucked into the socket region and organization of the coagulum in the socket region may be disrupted. In addition, the surgical area is left unprotected against oral pathogens and food residue. This condition leads to delayed wound healing and increases the risk of developing alveolar osteitis. Hence, existing wound dehiscence at the distofacial edge of the second molar probably extends the postsurgical treatment period. This may lead to an elevated level and duration of postoperative pain and discomfort. Furthermore, potential periodontal complications distal to the preceding second molar may also occur. Numerous investigators advocate using primary wound closure after mandibular third molar surgery to obtain quicker mucosal healing and superior amounts of bone regeneration.

Various incision and flap techniques, each with variations, have been performed for third molar surgery. The envelope flap and triangular flap are the most commonly use and preferred flap designs in impacted third molar surgery. The aim of this study was to compare a new flap design with the routinely used triangular flap design in the surgical removal of impacted mandibular third molars.

Materials and methods

This randomized, prospective, split-mouth study was performed at the Department of Oral and Maxillofacial Surgery, Faculty of Dentistry, Inönü University. It involved 22 patients with impacted bilateral mandibular third molars that were symmetrically positioned, mesially angulated, and retained in bone. The exclusion criteria were the following: history of systemic disease, use of medications, poor oral hygiene and compromised dental and periodontal status, smoking habit, allergy or contraindications to the drugs or anaesthetics used in the study, pregnancy or lactation, and a noticeable local inflammation or pathology in the oral cavity that would influence the surgical procedure or postoperative wound healing.

Before the procedure, each participant was informed about the surgical and postoperative study protocol. Signed consent indicating their agreement to participate in the study was obtained. The study was approved by the relevant ethics committee.

All surgical procedures were carried out by the same surgeon (UY), who has more than 10 years of experience as a specialist in oral and maxillofacial surgery. For each patient, the impacted teeth were removed in two sessions using the two different flap designs. The time interval between the two sessions was at least 4 weeks. The flap design and operated side of the mouth were assigned randomly for each patient using envelopes prepared in advance. The side of the first operation was defined by the patient.

Before starting the procedure, the oral cavity was rinsed thoroughly with diluted povidone iodine solution for 30 s. Three millilitres of articaine HCl 4% with 1:200,000 epinephrine (Ultracaine D-S Ampul; Sanofi Aventis, Istanbul, Turkey) was used as the local anaesthetic agent for inferior alveolar and lingual nerve block (2 ml), along with vestibular infiltration (1 ml).

Flaps were made using two techniques. For technique A ( n = 22 teeth), the impacted teeth were removed using a buccally based triangular flap, as first described by Szymd. An incision was made from the anterior border of the mandibular ramus to the distal surface of the distobuccal cusp of the mandibular second molar. It was extended along the sulcus to the distobuccal corner of the second molar crown. The incision was continuous, with a relieving vertical incision, oblique into the mandibular vestibular fornix, aligned with the mesiobuccal cusp of the second molar ( Fig. 1 ).

Fig. 1
Incision for the buccally based triangular flap.

For technique B ( n = 22 teeth), a lingually based triangular flap was used to remove the impacted mandibular third molar on the contralateral side of the patient. An incision was made adjacent to the distal surface of the mandibular second molar, and extended along the sulcus to the distobuccal corner of the mandibular second molar. An oblique vestibular incision was made and extended into the vestibular fornix of the mandible, aligned with the mesiobuccal cusp of the second molar. It was continued postero-superiorly towards the anterior border of mandibular ramus ( Figs 2 and 3 ).

Fig. 2
Incision for the lingually based triangular flap.

Fig. 3
Intraoperative image of the lingually based triangular flap.

A mucoperiosteal flap was raised ( Fig. 4 ). Bone was removed with a round bur under copious irrigation with 0.9% sterile saline, following which the tooth was extracted. When necessary, the tooth was sectioned with a fissure bur. Primary wound closure was accomplished using 4–0 silk sutures. The buccally based triangular flap was closed with three single sutures distal to the second molar and three single sutures in the perpendicular incision line ( Fig. 5 ). For the lingually based triangular flap, the same suturing technique was used vertically, and the posterior portion of the incision was sutured with four single sutures ( Figs 6 and 7 ). The duration of each procedure from the start of the incision to the time of last suture placement was noted. Further, the need or lack thereof for tooth sectioning was recorded.

Fig. 4
Raising of the mucoperiosteal flap in the lingually based triangular flap technique.

Fig. 5
Closure of the buccally based triangular flap.

Fig. 6
Closure of the lingually based triangular flap.

Fig. 7
Intraoperative image of closure of the lingually based triangular flap.

Following surgery, the patients were prescribed paracetamol (Minoset, 500 mg 3 × 1; Bayer Turk, Istanbul, Turkey) and chlorhexidine gluconate/benzydamine hydrochloride mouth wash (Kloroben, 3 × 1; Drogsan, Ankara, Turkey) for 3 days and 5 days, respectively. Antibiotics were not prescribed before or after the procedure. Sutures were removed on day 7 postoperative.

Patients were recalled on days 2, 7, 14, and 21 postoperative, and were evaluated for the parameters of pain, facial swelling, maximum mouth opening, wound dehiscence, and other variables. During each postoperative visit, data were collected and recorded by the same surgeon (AHA) who was blinded to the surgical technique used.

Trismus was assessed by measuring the maximum inter-incisal opening (in millimetres) – the distance between the incisal margin of the upper and lower central incisors – using a standard ruler. This measurement was repeated twice.

The level of postoperative pain was evaluated using a 10-cm visual analogue scale (VAS), with zero representing no pain and 10 representing excruciating pain. Patients were asked to mark the position of their pain along the scale at 6 h and 12 h after the operation and in the morning for 7 days post-surgery. The VAS was converted to a numerical value by millimetre measurement.

For the objective evaluation of swelling, five distances were measured: (a) the distance from the mandibular angle to the lateral corner of the mouth; (b) the distance from the mandibular angle to the nasal alar curvature, (c) the distance from the mandibular angle to the lateral canthus of the eye, (d) the distance from the tragus to the soft tissue pogonion, and (e) the distance from the tragus to the lateral corner of the mouth. Measurements were performed twice with a thread, transferred to a ruler, and recorded. The facial measurement was calculated as: (a + b + c + d + e)/5. The percentage of facial swelling (%) was calculated as: [(postoperative measurement–preoperative measurement)/preoperative measurement] × 100.

The presence of alveolar osteitis (dry socket) was determined clinically using Blum’s criteria. On days 7, 14, and 21 postoperative, wound healing was assessed and recorded as primary or secondary, depending on the absence or presence of dehiscence, respectively. Every opening along the incision was recorded as a wound dehiscence. Dental tweezers were used to identify dehiscence.

Statistical analysis

Data were analyzed using IBM SPSS Statistics version 21.0 (IBM Corp., Armonk, NY, USA). Data for individual parameters were initially tested for normal distribution using the Shapiro–Wilk test. Differences in individual parameters among the groups were tested using an independent sample t -test for normally distributed variables (trismus and operation time) and the Mann–Whitney U -test for non-normally distributed variables (swelling and pain). Additionally, Pearson’s correlation test was used to assess if a statistically significant relationship existed between two categorical variables. Differences were considered significant if the P -value was less than 0.05.

Results

A total of 22 patients (16 women and six men), aged between 19 and 28 years (mean ± standard deviation, 22.23 ± 2.49 years), participated in this study.

The average time taken to perform the surgery was 18.23 ± 6.17 min for the buccally based triangular flap group and 20.41 ± 3.97 min for the lingually based triangular flap group ( P = 0.17).

Bone was removed in all cases; teeth were sectioned in 13 cases (59.1%) in the buccally based triangular flap group and in 11 cases (50%) in the lingually based triangular flap group ( P = 0.55).

When compared to the buccally based triangular flap group, the lingually based triangular flap group exhibited the following: (1) a higher mean VAS score at 12 h post-surgery, which was statistically significant ( P = 0.04); (2) higher pain scores at 6 h and on each of the first 7 days post-surgery, although this was not statistically significant ( P > 0.05) ( Table 1 ); and (3) inferior maximal inter-incisal mouth opening from day 2 to day 21 postoperative, although the difference was not statistically significant ( P > 0.05) ( Table 2 ).

Table 1
Pain levels assessed by VAS (in millimetres).
Time of assessment post-surgery Buccally based triangular flap (mean ± SD) Lingually based triangular flap (mean ± SD) P -value a
6 h 53.82 ± 2.82 65.68 ± 2.24 0.16
12 h 52.59 ± 2.79 69.95 ± 2.31 0.04 *
1 day 35.04 ± 24.27 47.32 ± 29.80 0.19
2 days 31.36 ± 29.96 39.41 ± 29.67 0.30
3 days 21.36 ± 24.11 31.68 ± 23.16 0.11
4 days 12.09 ± 15.51 20.86 ± 21.23 0.11
5 days 14.91 ± 21.23 15.14 ± 17.07 0.61
6 days 6.50 ± 12.01 12.68 ± 17.21 0.24
7 days 4.73 ± 10.08 8.64 ± 15.44 0.25
VAS, visual analogue scale; SD, standard deviation.

a P -value, Mann–Whitney U -test.

* P < 0.05.

Table 2
Maximum inter-incisal opening (in millimetres).
Time of assessment post-surgery Buccally based triangular flap (mean ± SD) Lingually based triangular flap (mean ± SD) P -value a
Preoperative 47.86 ± 5.44 48.50 ± 4.98 0.69
2 days 28.05 ± 7.84 25.23 ± 8.36 0.26
7 days 37.41 ± 8.25 34.23 ± 8.82 0.22
14 days 44.59 ± 6.32 41.82 ± 8.30 0.22
21 days 47.50 ± 5.54 45.95 ± 5.85 0.37
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Jan 17, 2018 | Posted by in Oral and Maxillofacial Surgery | Comments Off on Comparison of a new flap design with the routinely used triangular flap design in third molar surgery
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