The surgical removal of lower third molar (wisdom) teeth is a. common oral surgery procedure. Typically, it is carried out because of infection associated with a partially erupted and impacted tooth. Infection may spread locally or more rarely threaten the airways. Post-operative complications include pain, swelling, alveolar osteitis (dry socket), trigeminal nerve injuries (inferior alveolar, lingual nerve) and, rarely, fracture of the mandible.

The aim of this Cochrane review was to compare the relative benefits and risks of different techniques for surgical removal of mandibular wisdom teeth.

Methods

Searches were conducted in the Cochrane Oral Health Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline, Embase ClinicalTrials.gov and the World Health Organization International Clinical Trials Registry Platform with no restrictions on the language or date of publication. Randomised controlled trials (RCTs) comparing different surgical techniques for the removal of mandibular wisdom teeth were considered.  The primary outcomes considered were alveolar osteitis (7 days), Infection seven (7 days), Permanent altered sensation of tongue, chin, or lip (> 6months), and adverse effects, such as reactionary bleeding or fracture of the mandible (up to 30 days).

Three reviewers were involved in assessing the studies, evaluating risk of bias and extracting data. Dichotomous data in parallel-group trials was reported as risk ratios (RRs) or Peto odds ratios (POR) if the event rate was low. Odds ratios (ORs) were used for dichotomous data in cross-over or split-mouth studies, and mean differences (MDs) for continuous data.  Analysis took account of the pairing of the split-mouth studies. A fixed-effect model was for three studies or fewer, and random-effects model for more than three studies.

Results

• 62 trails involving 4643 studies were included.
• 33 (53%) were considered to be at high risk of bias and 29 at unclear risk.
• There is insufficient evidence to determine whether envelope or triangular flap designs led to
  • more alveolar osteitis, OR= 0.33 (95%CI; 0.09 to 1.23) [ 5 studies; low-certainty evidence (LCE)]
  • wound infection, OR= 0.29 (95%CI; 0.04 to 2.06) [2 studies; LCE], or
  • permanent altered tongue sensation, POR = 4.48 (95%CI; 0.07 to 286.49) [1 study; very LCE( VLCE)].
  • 2 studies reported wound dehiscence at up to 30 days after surgery but found no difference in risk between interventions.
• 1 RCT [VLCE] provided insufficient evidence to determine whether the use of a lingual retractor compared to not using one affected the risk of permanent altered sensation, POR=0.14 (95%CI; 0.00 to 6.82).
• There is insufficient evidence to determine whether lingual split with chisel is better than a surgical handpiece for bone removal in terms of
  • Wound infection OR= 1.00 (95%CI; 0.31 to 3.21) [1 study; VLCE].
  • Alveolar osteitis, Permanent altered sensation, and other adverse effects were not reported.
• There is insufficient evidence to determine whether there is any difference in alveolar osteitis according to
  • irrigation method -mechanical versus manual, RR =0.33 (95%CI; 0.01 to 8.09) 1 study VLCE or
  • irrigation volume – high versus low; RR=0.52, (95%CI; 0.27 to 1.02) 1 study VLCE, or
• whether there is any difference in postoperative infection according to
  • irrigation method-mechanical versus manual: RR 0.50, 95% CI 0.05 to 5.43; 1 study VLCE or
  • irrigation volume -low versus high; RR 0.17, 95% CI 0.02 to 1.37; 1 study VLCE).
• There is insufficient evidence to determine whether primary or secondary wound closure led to
  • more alveolar osteitis, RR= 0.99 (95%CI; 0.41 to 2.40) 3 studies; LCE,
  • wound infection, RR= 4.77 (95%CI 0.24 to 96.34) 1 study; VLCE, or
  • adverse effects (bleeding), RR= 0.41 (95%CI; 0.11 to 1.47) 1 study; VLCE; permanent sensation changes were not reported in these studies.
• 2 studies LCE suggest placing platelet rich plasma (PRP) or platelet rich fibrin (PRF) in sockets may reduce the incidence of alveolar osteitis OR= 0.39 (95%CI; 0.22 to 0.67).

Conclusions

The authors concluded: –

In this 2020 update, we added 27 new studies to the original 35 in the 2014 review. Unfortunately, even with the addition of these studies, we have been unable to draw many meaningful conclusions. The small number of trials evaluating each comparison and reporting our primary outcomes, along with methodological biases in the included trials, means that the body of evidence for each of the nine comparisons evaluated is of low or very low certainty.

Participant populations in the trials may not be representative of the general population, or even the population undergoing third molar surgery. Many trials excluded individuals who were not in good health, and several excluded those with active infection or who had deep impactions of their third molars.

Consequently, we are unable to make firm recommendations to surgeons to inform their techniques for removal of mandibular third molars. The evidence is uncertain, though we note that there is some limited evidence that placing PRP or PRF in sockets may reduce the incidence of dry socket. The evidence provided in this review may be used as a guide for surgeons when selecting and refining their surgical techniques. Ongoing studies may allow us to provide more definitive conclusions in the future.

Comments

This Cochrane review has been undertaken using Cochrane’s well-established methods and updates an earlier version published in 2014 (Dental Elf – 4^th Aug 2014).  Although the authors well able to add another 27 studies to the 35 included in the previous version they were still unable to provide meaningful conclusions. While a large number of new trials were available for this update the authors commented on their small sample sizes. They also highlighted the large proportion of split-mouth studies many of which were treated in the same operative session. While this has apparent efficiency if may present difficulties in attributing outcomes (eg pain or trismus) to the intervention or the control. The need to properly account for this paired data in the analysis was also note.  Although improvements in the quality of studies overtime was noted the risk of bias for the included studies was high (50%) or unclear with no studies being considered to be at low risk of bias. Future studies need to make more consistent use of SPIRT and CONSORT statements to increase the value of research in this area.

Links

Primary Paper

Bailey E, Kashbour W, Shah N, Worthington HV, Renton TF, Coulthard P. Surgical techniques for the removal of mandibular wisdom teeth. Cochrane Database of Systematic Reviews 2020, Issue 7. Art. No.: CD004345. DOI: 10.1002/14651858.CD004345.pub3.

Other references

Cochrane Oral Health Group – Methods of removing wisdom teeth from the lower jaw

Dental Elf  – 27^th May 2020

Third molars: Remove or retain asymptomatic disease-free impacted teeth?

Dental Elf  – 4^th  Aug 2014

Available evidence for various aspects of surgical removal of third molars is very low to moderate

 

Dental Elf – Third Molar Blogs