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. 2014 Aug 29;2014:1302.

Impacted wisdom teeth

Thomas B Dodson 1,#, Srinivas M Susarla 2,#
PMCID: PMC4148832  PMID: 25170946

Abstract

Introduction

The incidence of impacted wisdom teeth (third molars) is high, with some 72% of Swedish people aged 20 to 30 years having at least one impacted wisdom tooth. Impacted wisdom teeth occur because of a lack of space, obstruction, or abnormal position. They can cause inflammatory dental disease manifested by pain and swelling of infected teeth and may destroy adjacent teeth and bone.

Methods and outcomes

We conducted a systematic review and aimed to answer the following clinical questions: Should asymptomatic, disease-free impacted wisdom teeth be removed prophylactically? What are the effects of different operative (surgical) techniques for removing impacted wisdom teeth? We searched: Medline, Embase, The Cochrane Library, and other important databases up to October 2013 (Clinical Evidence reviews are updated periodically; please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We performed a GRADE evaluation of the quality of evidence for interventions.

Results

We found 11 studies that met our inclusion criteria.

Conclusions

In this systematic review, we present information relating to the effectiveness and safety of the following interventions: prophylactic extraction, active surveillance, and different operative (surgical) techniques for extracting impacted wisdom teeth.

Key Points

Impacted wisdom teeth (third molars) occur because of a lack of space, obstruction, or abnormal position.

  • They can cause pain, swelling, and infection, and may destroy adjacent teeth and bone.

  • The incidence of impacted wisdom teeth is high, with some 72% of Swedish people aged 20 to 30 years having at least one impacted wisdom tooth.

Non-RCT evidence indicates that about one third of asymptomatic, unerupted wisdom teeth will change position, resulting in wisdom teeth that are partially erupted but non-functional or non-hygienic.

  • Between 30% and 60% of people who retain their asymptomatic wisdom teeth proceed to extraction of one or more of them between 4 and 12 years after their first visit.

Removal of impacted wisdom teeth (symptomatic and asymptomatic) is a commonly performed procedure.

While symptomatic or diseased impacted wisdom teeth should be recommended for removal, current evidence neither refutes nor confirms the practice of prophylactic removal of asymptomatic, disease-free wisdom teeth.

  • Some non-RCT evidence indicates that extraction of the asymptomatic tooth may be beneficial when disease, such as caries, is present in the adjacent second molar, or if periodontal pockets are present distal to the second molar.

We do not know whether active surveillance is effective for asymptomatic, disease-free wisdom teeth, as we found no RCTs or prospective cohort studies on this topic.

We don't know which is the most effective operative (surgical) technique for extracting impacted wisdom teeth.

About this condition

Definition

Wisdom teeth are present in most adults, and they generally become apparent between the ages of 18 and 24 years, although there is wide variation in the age of presentation. Impacted wisdom teeth are third molars that are not ordinarily expected to erupt into functional teeth. Wisdom teeth become partially or completely impacted owing to lack of space, obstruction, or abnormal position. Impacted wisdom teeth may be diagnosed because of symptoms such as pressure, pain, or swelling; by physical examination with probing or direct visualisation; or incidentally by routine dental radiography.

Incidence/ Prevalence

Wisdom tooth (third molar) impaction is common. More than 72% of Swedish people aged 20 to 30 years have at least one impacted lower wisdom tooth. Removal of impacted wisdom teeth (symptomatic and asymptomatic) is a commonly performed operation. The incidence of wisdom tooth removal is estimated to be 4 per 1000 person-years in England and Wales, making it one of the top 10 inpatient and day-case procedures. In a report from 1994, up to 90% of people on oral and maxillofacial surgery hospital waiting lists were awaiting removal of wisdom teeth. Fewer operations are done now, possibly because of guidance.

Aetiology/ Risk factors

Wisdom tooth impaction may be more common now than in the past, as modern diet tends to be softer.

Prognosis

Impacted wisdom teeth can cause pain, swelling, and infection, and may destroy adjacent teeth and bone. The removal of diseased or symptomatic wisdom teeth alleviates pain and suffering, and improves oral health and function. About one third of asymptomatic, unerupted wisdom teeth have been found to change position with time, resulting in wisdom teeth that are partially erupted but non-functional or non-hygienic. Three prospective cohort studies have also demonstrated that 30% to 60% of people with previously asymptomatic impacted wisdom teeth will undergo extraction of one or more of their wisdom teeth because of symptoms or disease, between 4 and 12 years following study enrolment. In another cohort study, a surprisingly high percentage (25%) of people with asymptomatic wisdom teeth had periodontal disease, as evidenced by probing depths greater than 5 mm. Probing depths could be an indicator of future periodontal status. One prospective cohort study demonstrated that 40% of people with asymptomatic wisdom teeth with probing depths of more than 4 mm had clinically significant progression of their periodontal status (probing depth increase of >2 mm) in the subsequent 24 months. The same study also found that, for those people with wisdom teeth with a probing depth of less than 4 mm, only 3% of teeth demonstrated progression of periodontal disease as evidenced by increasing probing depths.

Aims of intervention

To maximise the benefits and minimise the adverse effects of wisdom-tooth management.

Outcomes

Dental disease: development or progression of asymptomatic or symptomatic inflammatory dental disease (e.g., caries, acute and chronic periodontal disease, pain); incisor crowding; disruption to regular activities of daily living (e.g., chewing, speaking, and missing work or education); days of disability; oral health profile; damage to adjacent teeth or restorations; maxillofacial lesions (e.g., odontogenic cysts or tumours); facial cellulitis of odontogenic origin; need for future treatment (e.g., extraction) of initially asymptomatic wisdom teeth. Complications or adverse effects of extraction: pain; swelling; prolonged or persistent trismus; persistent or excessive bleeding; surgical-site infection with or without cellulitis or osteomyelitis; disruption to regular activities of daily living (e.g., chewing, speaking, and missing work or education); wound dehiscence; alveolar osteitis; new or persistent periodontal defects on the adjacent teeth; damage to adjacent teeth or restorations; temporary, permanent, or prolonged symptoms related to inferior alveolar or lingual nerve injuries; maxillary tuberosity fracture; temporary or persistent oro-antral communication with or without sinusitis.

Methods

Clinical Evidence search and appraisal October 2013. The following databases were used to identify studies for this systematic review: Medline 1966 to October 2013, Embase 1980 to October 2013, and The Cochrane Database of Systematic Reviews 2013, issue 10 (1966 to date of issue). Additional searches were carried out in the Database of Abstracts of Reviews of Effects (DARE) and the Health Technology Assessment (HTA) Database. We also searched for retractions of studies included in the review. Titles and abstracts identified by the initial search, run by an information specialist, were first assessed against predefined criteria by an evidence scanner. Full texts for potentially relevant studies were then assessed against predefined criteria by an evidence analyst. Studies selected for inclusion were discussed with an expert contributor. All data relevant to the review were then extracted by an evidence analyst. Study design criteria for inclusion in this review were: published RCTs and systematic reviews of RCTs in the English language, containing at least 20 individuals (at least 10 per treatment arm). Split mouth studies were included, but outcomes on incisor crowding in these studies were not reported due to confounding. There was no minimum length of follow-up, no required level of blinding, and no maximum loss to follow-up (except for Question 2, which implemented a maximum loss to follow-up of 20%). Additionally, specific to Question 1, prospective cohort studies with control groups were included. We included RCTs and systematic reviews of RCTs where harms of an included intervention were assessed, applying the same study design criteria for inclusion as we did for benefits. In addition, we use a regular surveillance protocol to capture harms alerts from organisations such as the FDA and the MHRA, which are added to the reviews as required. To aid readability of the numerical data in our reviews, we round many percentages to the nearest whole number. Readers should be aware of this when relating percentages to summary statistics such as relative risks (RRs) and odds ratios (ORs). We have performed a GRADE evaluation of the quality of evidence for interventions included in this review (see table). The categorisation of the quality of the evidence (high, moderate, low, or very low) reflects the quality of evidence available for our chosen outcomes in our defined populations of interest. These categorisations are not necessarily a reflection of the overall methodological quality of any individual study, because the Clinical Evidence population and outcome of choice may represent only a small subset of the total outcomes reported, and population included, in any individual trial. For further details of how we perform the GRADE evaluation and the scoring system we use, please see our website (www.clinicalevidence.com).

Table.

GRADE Evaluation of interventions for Impacted wisdom teeth.

Important outcomes Complications or adverse effects of extraction, Dental disease
Studies (Participants) Outcome Comparison Type of evidence Quality Consistency Directness Effect size GRADE Comment
Should asymptomatic, disease-free impacted wisdom teeth be removed prophylactically?
1 (164) Dental disease Prophylactic extraction versus no extraction plus no active surveillance 4 –2 0 –1 0 Very low Quality points deducted for sparse data and large loss to follow-up (over 50%); directness point deducted for unclear clinical importance of results
What are the effects of different operative (surgical) techniques for removing impacted wisdom teeth?
7 (at least 252) Complications or adverse effects of extraction Bone-removal techniques versus each other 4 –2 0 –1 0 Very low Quality points deducted for incomplete reporting of results and weak methods; directness point deducted for heterogeneity between RCTs
2 (359) Complications or adverse effects of extraction Coronectomy versus complete removal of wisdom tooth 4 –2 0 –2 0 Very low Quality points deducted for incomplete reporting of results and weak methods; directness points deducted for restricted population in RCTs (high risk of nerve injury) affecting generalisability and small number of events for many outcomes, affecting power to detect differences between groups
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We initially allocate 4 points to evidence from RCTs, and 2 points to evidence from observational studies. To attain the final GRADE score for a given comparison, points are deducted or added from this initial score based on preset criteria relating to the categories of quality, directness, consistency, and effect size. Quality: based on issues affecting methodological rigour (e.g., incomplete reporting of results, quasi-randomisation, sparse data [<200 people in the analysis]). Consistency: based on similarity of results across studies. Directness: based on generalisability of population or outcomes. Effect size: based on magnitude of effect as measured by statistics such as relative risk, odds ratio, or hazard ratio.

Glossary

Very low-quality evidence

Any estimate of effect is very uncertain.

Disclaimer

The information contained in this publication is intended for medical professionals. Categories presented in Clinical Evidence indicate a judgement about the strength of the evidence available to our contributors prior to publication and the relevant importance of benefit and harms. We rely on our contributors to confirm the accuracy of the information presented and to adhere to describe accepted practices. Readers should be aware that professionals in the field may have different opinions. Because of this and regular advances in medical research we strongly recommend that readers' independently verify specified treatments and drugs including manufacturers' guidance. Also, the categories do not indicate whether a particular treatment is generally appropriate or whether it is suitable for a particular individual. Ultimately it is the readers' responsibility to make their own professional judgements, so to appropriately advise and treat their patients. To the fullest extent permitted by law, BMJ Publishing Group Limited and its editors are not responsible for any losses, injury or damage caused to any person or property (including under contract, by negligence, products liability or otherwise) whether they be direct or indirect, special, incidental or consequential, resulting from the application of the information in this publication.

Contributor Information

Thomas B. Dodson, Associate Dean for Hospital Affairs, University of Washington School of Dentistry, Seattle, US.

Dr Srinivas M. Susarla, Department of Plastic and Reconstructive Surgery, Johns Hopkins Hospital, Baltimore, US.

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BMJ Clin Evid. 2014 Aug 29;2014:1302.

Prophylactic extraction of asymptomatic, disease-free impacted wisdom teeth

Summary

We don’t know whether early extraction of asymptomatic, disease-free impacted wisdom teeth is more effective at improving incisor crowding (as indicated by measures of incisor irregularity, inter-canine width, or arch length) compared with no extraction plus no active surveillance.

We found no direct information from RCTs or prospective cohort studies with a control group that met Clinical Evidence: inclusion criteria on complications or adverse effects of early extraction of asymptomatic, disease-free, impacted wisdom teeth compared with no extraction plus no active surveillance.

In summary, we did not find any evidence that prophylactic extraction of impacted wisdom teeth was more effective at improving incisor crowding compared with no extraction plus no active surveillance.

Benefits and harms

Prophylactic extraction versus no extraction plus no active surveillance:

We found five systematic reviews evaluating the extraction of impacted wisdom teeth (search dates 1997; 2000; 2003; and 2012 ), which between them identified one RCT that met Clinical Evidence inclusion criteria. We have reported the RCT directly from the original report. One further RCT on incisor crowding was identified. However, this was a split-mouth study, and we do not report incisor crowding as an outcome for this type of study (see Comment). The fourth systematic review also identified a further RCT that was discontinued, the results of which have not yet been published.

Dental disease

Prophylactic extraction compared with no extraction plus no active surveillance We don't know whether early wisdom tooth extraction is more effective at improving incisor crowding (as indicated by measures of incisor irregularity, inter-canine width, or arch length) at 5 years in people aged 14 to 18 years with asymptomatic, disease-free impacted wisdom teeth (very low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Dental disease

RCT		 164 people, aged 14–18 years, with asymptomatic impacted wisdom teeth Mean change from baseline in incisor irregularity 5 years
0.80 mm with early third-molar extraction
1.10 mm with no extraction of third molars
P = 0.56 		Not significant

RCT		 164 people, aged 14–18 years, with asymptomatic impacted wisdom teeth Mean change from baseline in inter-canine width 5 years
–0.37 mm with early third-molar extraction
–0.38 mm with no extraction of third molars
P = 0.92 		Not significant

RCT		 164 people, aged 14–18 years, with asymptomatic impacted wisdom teeth Mean change from baseline in arch length 5 years
–1.1 mm with early third-molar extraction
–2.13 mm with no extraction of third molars
P = 0.001
The authors of this RCT did not consider this difference to be clinically important 		Effect size not calculated extraction
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Adverse effects

No data from the following reference on this outcome.

Prophylactic extraction versus active surveillance:

We found no systematic review, RCTs, or prospective cohort studies with a control group comparing extraction versus active surveillance in people with asymptomatic, disease-free impacted wisdom teeth. See also harms from Extraction of impacted wisdom teeth: different operative (surgical) techniques.

Comment

The further RCT (52 people with unerupted wisdom teeth, aged 13–19 years) compared extraction of impacted wisdom teeth versus no extraction (people had impacted wisdom teeth on both sides of the lower jaw, and one molar was randomly selected for removal, and the non-extraction side acted as a control). The RCT was excluded from the fourth review, as it was felt that a split-mouth study was not an appropriate study design to assess incisor crowding. The RCT reported that incisor crowding (measured using the length of the arch: a straight line between the central fossa of the second molar and the incisal cross) did not change differently on the extraction side compared with the no extraction side at 3 years (absolute results not reported and significance not assessed). The RCT reported that 19 teeth in the control side were extracted 'for various reasons' (timescale not clear, further details not reported). The RCT found that postoperative adverse effects (pain, infection, or limited mouth opening) occurred in 4/52 (8%) teeth and secondary haemorrhage in 2/52 (4%) teeth in the extraction group. Adverse effects in the control group were not reported.

Clinical guide:

Prospective cohort studies have shown that 30% to 60% of asymptomatic patients may develop disease or become sufficiently symptomatic to warrant extraction. Delaying extraction of asymptomatic teeth could result in an increased risk for postoperative inflammatory complications and prolonged recovery after extraction. One treatment guideline for managing unerupted and impacted wisdom teeth (search date 2000; 8 clinical studies of different designs; number of people not reported) suggested that removal of asymptomatic disease-free wisdom teeth may be beneficial in the presence of caries in the adjacent second molar, which cannot be properly treated without the removal of the wisdom teeth. Extraction may also be beneficial in the presence of periodontal pockets distal to the second molar.

The harms associated with prophylactic extraction of asymptomatic, disease-free wisdom teeth are the expected adverse effects associated with any operation (e.g., costs, pain and swelling, loss of work or school time, and undergoing unnecessary surgery). The removal of the lower wisdom teeth also carries the risk of damage to the inferior alveolar nerve (injured in 1%–8% of people and permanently damaged in up to 1% of people), and to the lingual nerve (permanently damaged in up to 1% of people, although a range of frequencies have been reported, including much lower rates). The risks seem to be greater with greater depth of impaction, and the risks are the same whether the wisdom tooth is symptomatic or asymptomatic. Observational studies have found limited evidence that the complications associated with the removal of wisdom teeth are more frequent when operators are less experienced, and in older people with deeply impacted teeth. See also harms from Extraction of impacted wisdom teeth: different operative (surgical) techniques.

Of note, the five systematic reviews identified offer different recommendations for management. This variation may be attributable to the different data identified by each review. The first review identified 12 literature reviews, the second review identified two RCTs and 34 literature reviews, the third review identified five cohort studies, the fourth review identified one RCT, and the fifth review identified four studies. The first and second systematic reviews both advocated against prophylactic removal, but acknowledged that the evidence supporting their position was weak. The third systematic review recommended against prophylactic removal, but, given the low level of evidence supporting this position, deferred to patient preference regarding treatment choice.The fourth systematic review concluded that there was no evidence to support or refute prophylactic removal of asymptomatic wisdom teeth. The fifth review concluded that there was a lack of scientific evidence to justify the indication of the prophylactic extraction of wisdom teeth.

When managing asymptomatic, disease-free wisdom teeth, no RCT data are available to guide therapeutic choices. Consistent with the application of evidence-based medicine principles, after a thorough review of the risks and benefits of the treatment alternatives, patient preference should be the factor driving the clinical decision.

Substantive changes

Prophylactic extraction of asymptomatic, disease-free impacted wisdom teeth One systematic review updated, and one systematic review added. Categorisation unchanged (unknown effectiveness).

BMJ Clin Evid. 2014 Aug 29;2014:1302.

Active surveillance of asymptomatic impacted wisdom teeth

Summary

We found no direct information from RCTs or prospective cohort studies with a control group to provide guidance as to whether active surveillance is better than extraction, or whether active surveillance is better than no extraction plus no active surveillance in people with asymptomatic impacted wisdom teeth.

Benefits and harms

Active surveillance versus no extraction plus no active surveillance:

We found no systematic review, RCTs, or prospective cohort studies with a control group comparing active surveillance versus no extraction plus no active surveillance in people with asymptomatic impacted wisdom teeth.

Active surveillance versus extraction:

We found no systematic review, RCTs, or prospective cohort studies with a control group comparing active surveillance versus extraction.

Different forms of active surveillance versus each other:

We found no systematic review, RCTs, or prospective cohort studies with a control group comparing different forms of active surveillance versus each other in people with asymptomatic impacted wisdom teeth. See also harms from Extraction of impacted wisdom teeth: different operative (surgical) techniques.

Comment

Clinical guide:

Active surveillance is defined for this review as scheduled clinical and radiographical evaluations of wisdom teeth on a regular basis by a healthcare professional trained to discern the disease status of wisdom teeth. The goal of active surveillance is to detect and treat disease early. The benefits of active surveillance include avoiding the costs and adverse effects of prophylactic removal of asymptomatic wisdom teeth. The risks of active surveillance include failure to detect disease in a timely manner due to clinical error or oversight, and failure of the patient to comply with the recommended follow-up schedule, which can lead to delayed extraction. Extraction in people older than 24 years can lead to decreased postoperative quality of life compared with extraction at a younger age.

Who should complete the active surveillance evaluations (either generalist or specialist), and the optimum frequency of the evaluations, are open to question: we found no RCTs on these issues. The benefit of having a specialist evaluate the patient lies in having an experienced clinician who will share in the responsibility and consequences of the management choice. However, there is concern that the specialist will remove impacted wisdom teeth unnecessarily. The benefits of having a generalist evaluate patients are decreased cost and increased patient convenience; however, there is concern that the generalist may miss disease or delay referral in a timely manner.

The benefits of more-frequent visits are the opportunity to detect and treat disease prior to the development of symptoms or damage to adjacent teeth or bone, and to prevent the progression of disease requiring treatment additional to the removal of the wisdom teeth (e.g., restoration or extraction of a carious second molar or the development of a jaw cyst or tumour). However, longer intervals between visits decrease costs, reduce exposure to radiation, and improve patient convenience. Non-RCT evidence indicates that clinically important changes in periodontal status can occur over a 24-month interval, and provides some basis for selecting examinations every 2 years.

Based on non-RCT evidence, when active surveillance is the recommended management option, the interval for follow-up should be 24 months. In addition to assessing the patient's symptoms, the examination should include physical and radiographical components.

Substantive changes

No new evidence

BMJ Clin Evid. 2014 Aug 29;2014:1302.

Extraction of impacted wisdom teeth: different operative (surgical) techniques (different bone removal techniques versus each other; complete extraction versus coronectomy)

Summary

We don’t know whether any one bone-removal technique is consistently more effective than any other at reducing complications or adverse effects of extraction of impacted wisdom teeth.

Only a small number of poor-quality RCTs comparing different bone-removal techniques were found.

We don’t know whether coronectomy or complete removal differ in their effectiveness for improving outcomes such as pain, delayed healing/infection, and dry socket in people thought to be at high risk of nerve injury.

Coronectomy may be more effective than complete removal at reducing inferior alveolar nerve damage in people thought to be at high risk of injury to the inferior alveolar nerve. However, the significance of some of the results was dependent on the exact analysis performed.

Benefits and harms

Bone-removal techniques versus each other:

We found one systematic review (search date 2010), one additional RCT, and two subsequent RCTs. The systematic review included four RCTs. It reported that the quality of RCTs was poor, and that allocation concealment and blinding was unclear in all four RCTs. It reported that, owing to the lack of quantitative data and heterogeneity, pooling of data was only possible for the outcomes of pain and swelling. The review noted that it was difficult to reach strong conclusions due to the small number of RCTs found, the small numbers of people involved, and the heterogeneity of study methods used.

Complications or adverse effects of extraction

Bone-removal techniques compared with each other We don’t know whether any one bone-removal technique is consistently more effective than any other at reducing complications or adverse effects of extraction, as we found insufficient evidence from small RCTs (very low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Pain

Systematic review		 82 people with impacted lower third molars
2 RCTs in this analysis		 Pain (assessed using a 4-point visual analogue scale) 7 days
with lingual split
with surgical bur
Absolute results not reported
P = 0.9661
The review also reported that there was no significant difference between groups at 24 hours (P = 0.0684) and 48 hours (P = 0.0719) postoperatively (2 RCTs, 82 people, absolute numbers not reported) 		Not significant

Systematic review		 20 people with impacted mandibular third molars
Data from 1 RCT		 Pain (assessed using a 100 mm visual analogue scale) Days 1 and 2 postoperatively
with lingual split
with surgical bur
Absolute results not reported
P = 0.12 		Not significant

Systematic review		 30 people with bilateral impacted lower third molars (split-mouth design)
Data from 1 RCT		 Pain (assessed by patients’ self-report of the most painful side) Day 1 and Day 7 postoperatively
8/27 (33%) with lingual split
18/27 (67%) with surgical bur
Significance not reported

RCT		 42 people with partially erupted lower third molars Proportion of people with pain scores 5/10 or more (measured by 10-point visual analogue scale) Day 7
4/20 (20%) with surgical bur
1/22 (5%) with erbium YAG laser
P = 0.2 		Not significant

RCT		 52 people with bilateral and symmetrically oriented impacted mandibular third molars (split mouth design) Mean pain scores (assessed using visual analogue scale, 0 = no pain, 100 = most severe pain imaginable) immediately postoperatively
47.23 with surgical bur
36.54 with piezoelectric device
P <0.05 		Effect size not calculated piezoelectric device

RCT		 52 people with bilateral and symmetrically oriented impacted mandibular third molars (split mouth design) Mean pain scores (assessed using visual analogue scale, 0 = no pain, 100 = most severe pain imaginable) Day 6 postoperatively
13.23 with surgical bur
10.12 with piezoelectric device
P >0.05
The RCT also reported no significant difference between groups on Days 1, 2, 3, 4, and 5 postoperatively 		Not significant

RCT		 26 people with lower impacted third molars (split-mouth design) Incidence of pain on palpation 30 days postoperatively
4/26 (15%) with surgical bur
5/26 (19%) with piezoelectric device
Reported as not significant
P value not reported
The RCT also reported no significant difference between groups at 7 days: 23/26 (88%) with surgical bur v 14/26 (54%) with piezoelectric device (P value not reported) 		Not significant
Swelling

Systematic review		 82 people with impacted lower third molars
2 RCTs in this analysis		 Swelling (assessed using a 4-point visual analogue scale) 7 days
with lingual split
with surgical bur
P = 0.2037
The review reported no significant difference between groups at 24 hours (P = 0.9734) and 48 hours (P = 0.6566) postoperatively 		Not significant

Systematic review		 20 people with impacted mandibular third molars
Data from 1 RCT		 Swelling (assessed using stereometric photogrammetry)
with lingual split
with surgical bur
Absolute results not reported
P = 0.88 		Not significant

Systematic review		 30 people with bilateral impacted lower third molars (split mouth design)
Data from 1 RCT		 Swelling (assessed by patients’ self-report of the most painful side) Day 1 and Day 7 postoperatively
8/27 (33%) with lingual split
18/27 (70%) with surgical bur
Significance not reported

RCT		 26 people with lower impacted third molars (split-mouth design)
Data from 1 RCT		 Incidence of persistent oedema 30 days
1/26 (4%) with surgical bur
1/26 (4%) with piezoelectric device
Reported as not significant
P value not reported
The RCT also reported no significant difference between groups at 7 days: 8/26 (31%) with surgical bur v 7/26 (27%) with piezoelectric device (P value not reported) 		Not significant
Delayed healing/infection

Systematic review		 52 people (split-mouth design) with bilateral impacted lower third molars Delayed healing/infection
3/52 (6%) with lingual split
3/52 (6%) with surgical bur
Reported as not significant
P values not reported 		Not significant

Systematic review		 20 people with impacted mandibular third molars
Data from 1 RCT		 Delayed healing
with lingual split
with surgical bur
The review reported that none of the group suffered delayed healing

Systematic review		 60 people with impacted mandibular third molars
Data from 1 RCT		 Delayed healing 7 days post-treatment
with lingual split
with surgical bur
The review reported 2 people in the lingual split group had “delayed healing probably due to wound infection”; further details not reported

Systematic review		 30 people with bilateral impacted lower third molars (split-mouth design)
Data from 1 RCT		 Delayed healing/infection
with lingual split
with surgical bur
It was reported that 1 person developed postoperative alveolitis (further details not reported)

RCT		 26 people with lower impacted third molars (split-mouth design) Incidence of pus 30 days
2/26 (8%) with surgical bur
0/26 (0%) with piezoelectric device
Reported as not significant
P value not reported
The RCT reported no significant difference between groups at 7 days: 1/26 (4%) with surgical bur v 0/26 (0%) with piezoelectric device (P value not reported) 		Not significant

RCT		 26 people with lower impacted third molars (split-mouth design) Incidence of dehiscence 30 days
4/26 (15%) with surgical bur
3/26 (12%) with piezoelectric device
Reported as not significant
P value not reported
The RCT reported no significant difference between groups at 7 days: 8/26 (31%) with surgical bur v 7/26 (27%) with piezoelectric device (P value not reported) 		Not significant
Disturbance of nerve function

Systematic review		 52 people (split mouth design) with bilateral impacted lower third molars
Data from 1 RCT		 Disturbance of lingual nerve function (recorded as present or absent by the person) 7 days postoperatively
1/52 (2%) with lingual split
4/52 (8%) with surgical bur
Reported as not significant
P value not reported
The review also reported on differences between groups at 6 hours (21% with lingual split v 23% with surgical bur), 24 hours (17% with lingual split v 23% with surgical bur) and 48 hours (10% with lingual split v 15% with surgical bur) postoperatively (absolute numbers not reported; P values not reported) 		Not significant

Systematic review		 60 people with impacted mandibular third molars
Data from 1 RCT		 Disturbance of lingual nerve function (assessed using a 4-point visual analogue scale) 24 hours postoperatively
2.6 with lingual split
2.9 with surgical bur
P = 0.004
The review also reported that there were no significant differences between groups at 48 hours postoperatively (2.8 with lingual split v 3.0 with surgical bur; P = 0.08) 		Effect size not calculated lingual split

Systematic review		 60 people with impacted mandibular third molars
Data from 1 RCT		 Disturbance of lingual nerve function (assessed using a 4-point visual analogue scale) 7 days postoperatively
2.9 with lingual split
3.0 with surgical bur
P = 0.36 		Not significant

Systematic review		 30 people with bilateral impacted lower third molars (split-mouth design)
Data from 1 RCT		 Disturbance of lingual nerve function
with lingual split
with surgical bur
The review reported that 7 people who reported worse pain and swelling on the surgical bur side experienced lingual paraesthesia, which resolved within 3 months

Systematic review		 52 people (split-mouth design) with bilateral impacted lower third molars
Data from 1 RCT		 Disturbance of inferior alveolar nerve function 7 days postoperatively
1/52 (2%) with lingual split
0/52 (0%) with surgical bur
Reported as not significant
P value not reported
The review also reported on differences between groups at 6 hours (12% with lingual split v 17% with surgical bur), 24 hours (10% with lingual split v 13% with surgical bur) and 48 hours (8% with lingual split v 8% with surgical bur) postoperatively (absolute numbers not reported; P values not reported) 		Not significant

Systematic review		 60 people with impacted mandibular third molars
Data from 1 RCT		 Disturbance of inferior alveolar nerve function (assessed using a 4-point visual analogue scale) 7 days postoperatively
3.0 with lingual split
3.0 with surgical bur
P = 1.0
The review also reported on differences between groups immediately postoperatively (1.0 for both lingual split and surgical bur; P value not reported) and at 24 hours (P = 0.36) and 48 hours (P = 1.0) postoperatively 		Not significant

Systematic review		 30 people with bilateral impacted lower third molars (split-mouth design)
Data from 1 RCT		 Disturbance of inferior alveolar nerve function
with lingual split
with surgical bur
The review reported that no person experienced sensory impairment (further details not reported)

Systematic review		 20 people with impacted mandibular third molars
Data from 1 RCT		 Disturbance of nerve function
with lingual split
with surgical bur
The review reported that “no one experienced sensory impairment of the inferior alveolar or lingual nerves” without further qualification

RCT		 26 people with lower impacted third molars (split mouth design) Disturbance of nerve function
with surgical bur
with piezoelectric device
The review reported there was “the absence of nerve lesions after either treatment”; further details not reported
Trismus

Systematic review		 20 people with impacted mandibular third molars
Data from 1 RCT		 Trismus (assessed using callipers) Days 1, 2, and 7 postoperatively
with lingual split
with surgical bur
P = 0.03
Further details not reported 		Effect size not calculated lingual split
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Coronectomy versus complete removal of wisdom tooth:

We found one systematic review (search date 2011), which included two RCTs. It only included people at high risk of nerve injury, as defined by radiography. Criteria for high risk of nerve injury included absence of cortical bone between third molar roots and nerve canals, third molar roots touching or overlapping the superior cortical line of nerve canals, loss of lamina dura of nerve canals, and darkening of third molar roots. Only studies that compared coronectomy with total removal for wisdom tooth extraction were included. No antibiotics were prescribed in the two RCTs. In the coronectomy group, roots that were loosened or mobilised during surgery were extracted. In one RCT (128 people), these were re-assigned to a third group called 'failed coronectomy', while the other RCT (231 people) did not consider them in subsequent analysis. The failure rates varied between the two RCTs (see comments). The review reported a per-protocol (treatment received) analysis and intention-to-treat (ITT) analysis. We have reported the ITT analysis unless otherwise stated.

Complications or adverse effects of extraction

Coronectomy compared with complete removal of wisdom tooth Coronectomy may be more effective than complete removal at reducing inferior alveolar nerve damage in people thought to be at high risk of injury to the inferior alveolar nerve. However, the significance of some results was dependent on the exact analysis performed. We don’t know whether coronectomy and complete removal differ in effectiveness at improving outcomes such as pain, delayed healing/infection, and dry socket in people thought to be at high risk of nerve injury (very low-quality evidence).

Ref (type) Population Outcome, Interventions Results and statistical analysis Effect size Favours
Pain

Systematic review		 128 people (196 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Pain 1 week postoperatively
12/94 (13%) molars with coronectomy
22/102 (22%) molars with complete removal
RR 0.59
95% CI 0.31 to 1.13 		Not significant

Systematic review		 231 people (349 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Pain 1 week postoperatively
69/171 (40%) molars with coronectomy
102/178 (57%) molars with complete removal
RR 0.70
95% CI 0.56 to 0.88
The RCT also reported that there was no significant difference between groups in pain score at 1 to 24 months (absolute numbers not reported, P value not reported) 		Small effect size coronectomy
Delayed healing/infection

Systematic review		 128 people (196 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Postoperative infection
3/94 (3%) molars with coronectomy
1/102 (1%) molars with complete removal
RR 3.26
95% CI 0.34 to 30.75 		Not significant

Systematic review		 231 people (349 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Postoperative infection 1 week postoperatively
10/171 (6%) molars with coronectomy
12/178 (7%) molars with complete removal
RR 0.87
95% CI 0.38 to 1.95
The RCT also reported that there was no incidence of infection from the third postoperative month in either group, and there was no statistical difference between the two groups throughout the follow-up period (further details not reported, P value not reported) 		Not significant
Disturbance of nerve function

Systematic review		 128 people (196 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Inferior alveolar nerve injury
5/94 (5%) molars with coronectomy
19/102 (19%) molars with complete removal
RR 0.29
95% CI 0.11 to 0.73
The review also reported a treatment received analysis in which 36 failed coronectomies were re-allocated to the complete removal group: 0/58 (0%) with coronectomy v 24/138 (17%) with complete removal, RR 0.05, 95% CI 0.00 to 0.78
See Comment section 		Moderate effect size coronectomy

Systematic review		 231 people (349 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Inferior alveolar nerve injury
2/171 (1%) molars with coronectomy
9/178 (5%) molars with complete removal
RR 0.23
95% CI 0.05 to 1.06
The review also reported a treatment received analysis in which 16 failed coronectomies were re-allocated to the complete removal group: 1/155 (1%) with coronectomy v 10/194 (5%) with complete removal, RR 0.13, 95% CI 0.02 to 0.97
See Comment section 		Not significant
Dry socket

Systematic review		 128 people (196 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Dry socket
11/94 (12%) molars with coronectomy
10/102 (10%) molars with complete removal
RR 1.19
95% CI 0.53 to 2.68 		Not significant

Systematic review		 231 people (349 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Dry socket 1 week postoperatively
0/171 (0%) molars with coronectomy
5/178 (3%) molars with complete removal
RR 0.09
95% CI 0.01 to 1.70 		Not significant
Re-operation

Systematic review		 128 people (196 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Re-operation
0/58 (0%) molars with coronectomy

Systematic review		 231 people (349 lower third molars) with high risk of nerve injury
Data from 1 RCT		 Re-operation
2/155 (1%) molars with coronectomy
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Comment

Of the RCTs identified, most did not specify whether people were symptomatic or asymptomatic.

Coronectomy versus complete removal of wisdom tooth:

In one RCT (128 people) comparing complete removal versus coronectomy, a large proportion of coronectomies failed (36/94 [38%]) as roots were dislodged during surgery. In the remaining RCT (231 people) included in the review, the failed coronectomy rate was 16/171 (9.4%).

Clinical guide:

While there has been disagreement about the removal of asymptomatic, disease-free wisdom teeth, there has been no controversy about the need to remove symptomatic teeth and those showing pathological changes such as infection, non-restorable caries, cysts, tumours, or destruction of adjacent teeth and bone. Most commonly, wisdom teeth are removed because they are impacted against bone or soft tissue, preventing them from fully erupting. Bacteria and debris collect under the overlying flap of tissue and cause infections (pericoronitis), and removal of wisdom teeth in this situation is the management of choice. Wisdom teeth are also removed if they are causing caries of the adjacent tooth. This happens when the tooth is partially erupted, and its position in relation to the adjacent tooth or soft tissues makes the area inaccessible to usual oral hygiene measures. The symptoms of pericoronitis are pain, bad taste, swelling of the gum and face, and restricted mouth opening (trismus). The local infection may spread, resulting in a regional lymphadenopathy, pyrexia, and malaise. Rarely, the swelling may threaten the patency of the airway and breathing. Wisdom tooth caries may also cause pain and, if unmanaged, will ultimately lead to death of the tooth and to abscess formation. Abscess, like pericoronitis, may result in pain, lymphadenopathy, pyrexia, malaise, and, rarely, also threaten the patency of the airway. Removal of the tooth alleviates the symptoms and prevents progress of the disease. It also permits restoration of the adjacent tooth caries. We found one systematic review (search date not reported), including eight studies (6 RCTs and 2 prospective cohorts), which suggested that, overall, the second-molar periodontal probing depth or attachment levels either remained unchanged or improved after wisdom-tooth removal. However, for the subset of people with healthy second-molar periodontium before surgery, the review found an increased risk for worsening of probing depths or attachment levels after wisdom-tooth removal. The clinical significance of this is not clear. There is currently insufficient evidence to show meaningful clinical benefit for one type of surgery versus another.

Substantive changes

Extraction of impacted wisdom teeth: different operative (surgical) techniques Two systematic reviews added, as well as two RCTs. Categorisation unchanged (unknown effectiveness).

Articles from BMJ Clinical Evidence are provided here courtesy of BMJ Publishing Group

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