Table 1. Characteristics of the studies which utilised BA-, BA+ and LS technique.
| Author | Location | Prospective / Retrospective | Subjects | Teeth numbers | Age (Years) | Intervention | Comparison | Outcome (Primary and Secondary) | Quantitative data |
| Akadiri et al. 2009 | Nigeria | Prospective | 79 | - | - | Three-sided buccal flap with buccal guttering BA-: 79 |
- | Incidence and duration of complicating nerve injuries | LNI (BA-) cases total: 3 (4.0%) LNI (Day 14) cases total: 1 (1%) |
| Baqain et al. 2010 | Jordan | Prospective | 321 M: 92 F: 229 |
443 |
Mean 22 Range: 16–66 |
Buccal mucoperiosteal flap BA-: 299 Buccal mucoperiosteal flap + lingual retraction using a Howarth periosteal elevator. BA+: 110 No data: 34 |
- | Presence of postoperative lingual neurosensory deficit | LNI (BA-) cases total: 1 LNI (BA+) cases total: 10 Recovery within 6 months: 11 Permanent cases total: 0 Lingual flap retraction: OR = 22.821 (95% Confidence Intervals: 2.83–183.83; p = 0.003) |
| Bataineh et al. 2001 | Jordan | Prospective | 741 M: 417 F: 324 |
741 | <20: 61 20–30: 467 >30: 213 |
Buccal approach using a crestal incision extending to the distal of the second molar followed by a second incision extending downward and forward to the buccal sulcus BA-: 525 Buccal flap elevation + lingual retraction using a Howarth periosteal elevator BA+: 216 |
- | The rate and factors influencing sensory impairment of the inferior alveolar and lingual nerves after the removal of impacted mandibular third molars under local anaesthesia | LNI (BA-) cases total: 7 LNI (BA+) cases total: 12 Recovery within 12 months: 19 Permanent cases total: 0 |
| Bataineh and Batarseh 2016 | Jordan | Prospective | 53 M: 23 F: 30 |
66 | Mean: 23.3 Range: 16–43 |
Modified buccal flap without elevation of lingual flap BA-: 66 |
- | Evaluate a modified flap design for removal of lower third molars with avoidance of lingual flap elevation and its effect on postsurgical lingual nerve sensory impairment. | LNI cases total: 0 |
| Charan babu et al. 2013 | India | Prospective | 100 M: 69 F: 31 |
100 | 16–25: 49 26–35: 36 36–45: 9 46–55: 4 55–65: 2 |
Moore/Gillbe collar technique after placement of Ward’s incision by a single oral surgeon BA-: 92 Moore/Gillbe collar technique after placement of Ward’s incision + lingual retraction with unspecified periosteal elevator BA+: 8 |
- | To evaluate the incidence and various risk factors influencing the sensory deficit in case of lingual nerve injury (LNI) in individuals whose impacted mandibular third molars are surgically removed under local anaesthesia. | LNI (BA-) cases total: 1 LNI (BA+) cases total: 3 Recovery within 3 months: 4 Permanent cases total: 0 |
| Cheung et al. 2010 | Hong Kong | Prospective | 3595 M: 39% F: 61% |
4388 | Mean 27.2 Range 14–82 |
Extraction of 8s with or without raising of lingual flap Lingual flap raised: 1427 (33%) Attempt made to protect lingual tissue: 3477 (80%) |
- | To determine the incidence of subsequent neurosensory deficit due to inferior alveolar nerve (IAN) and lingual nerve (LN) injury, to examine possible contributing risk factors and to describe the pattern of recovery | LNI cases total: 30
Recovery after 24 months: 18/25 Permanent cases total: 7 (persist >2 years) (0.16%) |
| Gargallo-albiol et al. 2000 | Spain | Prospective (RCT) |
300 M: 140 F: 160 |
300 Totally impacted: 80 Partially erupted: 220 |
Mean: 27.4 Range: 14–59 |
Buccal mucoperiosteal flap BA-: 158 Buccal mucoperiosteal flap + lingual retraction with unspecified instrument BA+: 142 |
Comparison between protection of the lingual flap and without protection of the lingual flap | To evaluate the efficacy of protecting the lingual nerve by subperiosteal insertion of a retractor in 300 patients | LNI (BA-) cases total: 1 LNI (BA+) cases total: 3 Recovery after 21 days: 3 Recovery after 60 days: 1 Permanent cases total: 0 |
| Ge et al. 2016 | China | Retrospective |
89 M: 46 F: 43 |
110 Deeply impacted: 47 Fully impacted: 63 |
Mean 33.2 Range: 22–56 |
Lingual split technique using piezosurgery all by the same surgeon under LA LS: 110 |
- | Primary outcome: Evaluate the effect and safety of lingual split technique using piezosurgery for the extraction of lingually positioned impacted mandibular 3rd molars Success rate, operating time (from the 1st incision to the last suture), and the incidence of major complications Secondary outcome: Pain, swelling, restricted mouth opening, and the postoperative symptom severity (PoSSe) score at the postoperative 7-day |
LNI (LS) cases total: 6 (5.5%) Permanent cases total: 0 |
| Gomes et al. 2005 | Brazil | Prospective (RCT) |
55 | 110 |
- | Buccal flap with a buccal retractor BA-: 55 Buccal flap with buccal retractor + lingual flap retraction using Free’s elevator BA+: 55 Patients were randomly allotted to have 1 side operated with buccal flap only and the other side with buccal and lingual flap retraction |
Without lingual flap retraction Same patient, different technique for opposite side of mouth |
Primary outcome: To clinically evaluate the frequency, type, and risk factors for lingual nerve damage after mandibular third molar surgery with reference to lingual flap retraction. | LNI (BA-) cases total: 0 LNI (BA+) cases total: 5 Recovered within 3 months: 5 Permanent cases total: 0 |
| Janakiraman and Sanjay 2010 | India | Prospective | 119 | 119 | Mean 27 Range: 18–35 |
Standard buccal Ward’s mucoperiosteal flap BA-: 6 Standard buccal Ward’s mucoperiosteal flap + lingual flap retraction with unspecified periosteal elevator BA+: 113 |
- | To determine the incidence of injury to the inferior alveolar and lingual nerves following surgical removal of impacted mandibular third molars and to evaluate the various factors contributing to the same. | LNI (BA-) cases total: 0 LNI (BA+) cases total: 5 Recovery in 6 months: 2 Still under observation (permanent): 1 |
| Jerjes et al. 2006 | United Kingdom | Prospective | 1087 M: 505 F: 585 |
1087 Partially erupted: 857 |
Mean 23.3 Range 17–46 |
Envelope mucoperiosteal flap reflected and bone removal with a round bur in a straight hand- piece. Sectioning of tooth when needed. No lingual flap employed. BA-: 1087 |
- | The proportion of permanent sensory impairment of the inferior alveolar and lingual nerves and the factors influencing such prevalence after the removal of mandibular third molars under local anaesthesia. | LNI (BA-) cases total: 71 Permanent tongue paraesthesia 2 years after surgery: 11 |
| Jerjes et al. 2010 | United Kingdom | Prospective |
3236 M: 1445 F: 1791 |
3236 Partially impacted: 2572 Close to IAC: 2531 |
Mean: 24.2 Range: 17–36 17–20: 852 21–25: 49.2 26–30: 471 >30: 319 |
An envelope mucoperiosteal flap reflected and bone was removed bucco-distally. No lingual flap employed. No lingual split technique used. BA-: 3236 |
- | Earlier reports, including a preliminary study within our unit, have shown that the surgeon’s experience is one of the most influential factors in determining the likelihood of both permanent inferior alveolar nerve (IAN) and lingual nerve (LN) paraesthesia, following third molar surgery. The effect of this and other factors influencing such prevalence are assessed in this study. | LNI (BA-) cases total: 57 Recovery after 6 months: 5 Recovery after 6–18 months: 15 Cases present 18–24 months after surgery: 37 |
| Kale et al. 2014 | - | Prospective | 20 M: 13 F: 7 |
- | - | Standard Wards’ incision made in all cases. The tissue flap was reflected buccally, distally and lingually. The wide end of Howarth’s elevator was inserted adjacent to the lingual plate to protect the lingual nerve. Bone guttering on the buccal, distal and lingual side using straight fissure bur in low speed micrometre straight handpiece under copious irrigation. BA+: 20 |
- | To assess the clinical feasibility of lingual bone guttering technique for surgical extraction of mandibular third molars. | LNI (BA+) cases total: 0 |
| Lata and Tiwari 2011 | India | Prospective | 90 | - | - | Standard Terence Ward`s incision was made and after reflecting the buccal flap, a gutter in the disto-buccal bone was created. Bone removal done with motor-driven surgical bur under constant saline irrigation. Odontectomy or odontotomy procedure was done depending on the path of removal of the impacted tooth. No use of lingual retractor. BA-: 90 |
- | To determine the clinical incidence of lingual nerve injury following mandibular third molar removal and to analyse possible factors for the lingual nerve injury. | LNI (BA-) cases total: 6 LNI (6 months after surgery) cases total: 1 |
| Majeed et al. 2018 | Pakistan | Prospective (RCT) |
300 | 300 Right: 170 Left:130 |
Range: 21–50 21–30: 245 31–40: 40 41–50: 15 |
BA-: 200 BA+: 100 No other information provided |
- | To determine the incidence of lingual nerve injury and the effects of different variables on lingual nerve injury during mandibular third molars removal surgery. | LNI cases total: 18
|
| Malden and Maidment 2002 | United Kingdom | Retrospective | 260 | 260 | - | Mucoperiosteal flap raised buccal to the third molar. Distal relieving incision placed on retromolar pad to avoid all anatomical variants of the lingual nerve. Retracted with a Bowdler Henry rake retractor or Austin retractor. Lingual tissue retracted only to expose the occlusal aspect of the tooth or the superior aspect of mandibular bone covering the tooth or the crest of the lingual plate. No raising or elevating a lingual mucoperiosteal flap off the lingual aspect of the mandible. Tooth section with bone removal: 102 Bone removal without tooth section: 74 Soft tissue surgery: 84 BA-: 260 |
- | To determine if the incidence of lingual nerve damage differed to any significant extent from that reported elsewhere. To modify the operative technique, if indicated, to bring the incidence of nerve damage to within an accepted currently published standard. |
LNI (BA-) cases total: 1 Permanent cases total: 0. Returned to full sensation within 6 weeks |
| Mavrodi et al. 2015 | Greece | Prospective | - | 1210 Left: 47.3% Right: 52.7% |
Mean 48.5 Range: 15–82 |
Full thickness mucoperiosteal 3-cornered flap used in all cases 1. Classical bur technique: 470 2. Elevator placed on the buccal surface of the impacted molar to luxate the alveolar socket more easily: 740 Tooth sectioned 57.4% in group 1, 32.7% in group 2 BA-: 1210 |
- | To compare the efficacy and the postoperative complications of patients to whom two different surgical techniques were applied for impacted lower third molar extraction. | LNI cases total: 0 |
| Moss and Wake 1999 | United Kingdom | Retrospective | 1614 M: 605 F: 1009 |
2906 Removed with a lingual flap: 2088 |
Range: 12–89 | Buccal mucoperiosteal flap retraction BA-: 818 Buccal mucoperiosteal flap retraction + lingual flap retraction with the Hovell’s and Rowe retractors. BA+: 2088 |
- | To establish whether the deliberate raising of a lingual flap to allow the insertion of a broad lingual flap retractor in itself had any effect on lingual nerve morbidity. | LNI (BA-) cases total: 2 LNI (BA+) cases total: 16 Recovery within: 0–2 weeks: 8 3–6 weeks: 8 7–12 weeks: 1 13–25 weeks: 1 No permanent lingual sensory disturbance |
| Nguyen et al. 2014 | Australia | Retrospective | 6803 | 11599 | - | Buccal flap with bone removal and tooth division BA-: 11599 |
- | To assess the incidence of and risk factors for permanent neuro- logic injuries to the inferior alveolar nerve (IAN) or lingual nerve (LN) after the removal of third molars. |
LNI (BA-) cases total: 15 (0.15%) Temporary LNI cases total: 7 (0.069%) Permanent LNI cases total: 8 (0.079%) |
| Obiechina et al. 2001 | Nigeria | Prospective | 517 M: 297 F: 220 |
717 | >16 |
Bur technique with preservation of lingual plate BA-: 699 Lingual bone split technique LS: 18 |
- | To analyse the depth of impaction of mandibular third molars, the type of anaesthesia, the surgical method used and the outcome. | LNI (BA-) cases total: 3 (0.4%) LNI (LS) cases total: 6 (0.8%) Complete recovery of lingual/labial sensation within 10–21 days Permanent case totals: 0 |
| Pogrel and Goldman 2004 | United States | Prospective | 250 | - | - | Buccal flap raised and an appropriate buccal retractor placed (usually Minnesota-type retractor). Lingual flap then raised using Molt or Ward’s periosteal elevator. Walter’s lingual retractor was then placed Lingual flap + buccal flap with a specially designed lingual retractor BA+: 250 |
- | The traditional approach in the United States has been a buccal approach avoiding exposure or surgery on the lingual side of the crest of the ridge. An alternative technique is to deliberately expose the lingual tissues and retract the lingual nerve lingually before tooth removal. This study reports a trial of this technique. | LNI (BA+) cases total: 4 Recovery within 21 days: 3 Recovery within 60 days: 1 Permanent cases total: 0 |
| Praveen et al. 2007 | India | Prospective (RCT) |
90 | 90 | Mean: 38 Range: 14–62 |
Buccal mucoperiosteal flap with buccal bone removal and tooth division + lingual nerve protection using Howarth’s periosteal elevator: BA+: 30 Buccal mucoperiosteal flap + lingual nerve protection using Howarth’s periosteal flap + normal/modified lingual split technique using a chisel LS: 60 |
- | To compare the morbidity rates of the three different surgical techniques and their efficacy with regard to postoperative pain, swelling, labial and lingual sensation. | LNI (BA+) cases total: 0 LNI (LS) cases total: 3 Recovery after 7 days: 1 Recovery after 14 days: 1 Permanent cases total: 1 |
| Ramadorai et al. 2019 | Singapore | Retrospective | 1276 M: 458 F: 818 |
1276 | Mean: 30.5 Range: 15–80 |
Buccal bone removal without raising a lingual flap BA-: 1276 |
- | To ascertain the incidence of IAN and LN damage after mandibular third molar surgery in National Dental Centre Singapore. Secondary outcome: To identify the contributory factors for the risk of IAN and LN nerve injury on the basis of the data collected. |
LNI (BA-) cases total: 1 Recovery after 3 months: 1 Permanent cases total: 0 |
| Robinson et al. 1999 | United Kingdom | Retrospective | 200 | 200 | - | Buccal flap elevation without elevation of lingual mucoperiosteal flap: BA-: 110 Buccal flap elevation + Howarth periosteal elevator eased across the distal bone to the lingual side: BA+: 90 |
- | - | LNI (BA-) cases total: 1 LNI (BA+) cases total: 3 Complete recovery within 3 months Permanent cases total: 0 |
| Shad et al. 2015 | Pakistan | Prospective (RCT) |
380 M: 179 F: 201 |
380 | Mean: 25.6 Range: 18–38 |
Buccal flap elevation without elevation of lingual mucoperiosteal flap: BA-: 190 Buccal and lingual flap retraction + lingual flap retraction with Howarth’s periosteal elevator BA+: 190 |
- | - | LNI (BA-) cases total: 5 LNI (BA+) cases total: 17 Permanent cases total (BA-): 1 Although all showed signs of recovery within 3–6 months, 21 cases showed spontaneous recovery |
| Smith 2013 | United Kingdom | Prospective | 1000 | 1589 | Mean 33.9 Range: 13–87 |
Buccal envelope mucoperiosteal flap. Lingual retraction was not used electively unless a significant amount of distal or distolingual bone removal was anticipated. BA-: 1455 LS: 134 |
- | To identify the relative risk of damage to the inferior dental (ID) and lingual nerves in patients undergoing lower third molar removal. | LNI (BA-) cases total: 3 LNI (LS) cases total: 2 Permanent cases total (BA-): 1 (0.06%) |
| Yadav et al. 2014 | India | Prospective | 1200 | 1200 | Range: 18–45 | Buccal mucoperiosteal flap BA-: 576 Buccal mucoperiosteal flap + lingual retraction with Howarth’s periosteal elevator BA+: 624 |
- | Investigate the incidence of sensory impairment of the lingual nerves following lower third molar removal and to compare the outcome with various operative variables. | 1 week (Temporary) LNI (BA-) cases total: 10 LNI (BA+) cases total: 57 6 months (Permanent) LNI (BA-): 1 LNI (BA+): 3 |
BA+—Buccal approach with lingual flap retraction; BA-—Buccal approach without lingual flap retraction; F—Female; LNI—Lingual nerve injury; LS—Lingual split technique; M—Male; RCT—Randomised controlled trials