Revolution vs status quo? Non-intervention strategy of asymptomatic third molars causes harm

Historical aspects about third molar removal versus retention and distal surface caries in the second mandibular molar adjacent to impacted third molars

This paper provides an insight into the historical recommendations regarding removal of mandibular third molars, as set out by the Royal College of Surgeons of England and the National Institutes of Health in the USA, as well as regional guidance from the National Institute for Health and Care Excellence and the controversy that surrounds surgical removal of third molars. The influences of third molar management as it developed in the UK, the historical economic evaluations, and the available evidence base on third-molar removal versus retention are described. This article seeks to address the growing concerns regarding the increasing frequency of distal surface caries (DSC) in mandibular second molar teeth when the decay is associated with asymptomatic, partially erupted, mandibular third molars, especially when they are mesially or horizontally impacted. Lastly, we illustrate radiographs of patients affected by DSC and how guidance that has been issued by a guideline institution regarding third molar surgery, even though it is based on insufficient evidence, is perceived as a strictly compulsory clinical strategy, and has been used in clinical practice in the UK for more than 20 years.

A systematic review of second molar distal surface caries incidence in the context of third molar absence and emergence

Objective The aim of this systematic review was to gain a greater insight into the incidence rates of distal surface caries (DSC) on second permanent molars.Data sources A literature search using the Cochrane Library, Lilacs, Embase and Medline via Ovid retrieved English and non-English language articles from inception to June 2016. The electronic searches were supplemented with reference searching and citation tracking. Reviewers independently and in duplicate performed data extraction and completed structured quality assessments using a validated risk of bias tool for observational studies and categorised the summary scores.Data selection The search yielded 81 records and, after application of inclusion and exclusion criteria, two incidence studies were included in this systematic review.Data extraction The DSC incidence was reported in one study as relative risk (RR = 2.53; 95% CI, 1.55 to 4.14) adjacent to erupted, (RR = 0.83; 95% CI, 0.11 to 6.04) soft tissue impacted and (RR = 1.44; 95% CI, 0.55 to 3.72) bony impacted third molars in comparison to when the third molar was absent with a 25-year follow-up. The second study reported a DSC incidence of 100 surface-years (1% of all sites) with an 18-month follow-up period.Conclusions Both cohort studies indicated that DSC incidence was higher when third molars were erupted in the intermediate term, but greater over the long term for an ageing male population. However, further high-quality research is required to improve the accuracy of these findings.

Does Retaining Third Molars Result in the Development of Pathology Over Time? A Systematic Review

PURPOSE

The present systematic review was conducted to assess the available literature on pathologies associated with third molar retention.

MATERIALS AND METHODS

A systematic literature search was conducted in MEDLINE (PubMed), Embase, and Cochrane Library and reported in accordance with the Preferred Reporting Items for Systematic reviews and Meta-Analyses guidelines. Relevant reports were selected using predefined inclusion and exclusion criteria. Pathology related to third molar retention included caries, periodontal pathology, second molar external root resorption, and pathologic widening of the third molar pericoronal space. The methodologic quality of each study was reviewed using a pathology-specific tool to assess the risk of bias.

RESULTS

A total of 37 studies were included for qualitative analysis. The available data showed that asymptomatic retained third molars frequently become diseased with increasing age of the patient and increased retention time. Caries and periodontal pathology were most frequently observed, especially in partially erupted third molars and mesially inclined mandibular third molars. Overall, the available data were regarded as medium to fair quality evidence.

CONCLUSIONS

The available data have revealed that retained asymptomatic third molars rarely remain disease-free over time. Increasing age and, thus, increasing retention time seemed associated with greater disease prevalence. Well-designed, prospective follow-up studies are needed to substantiate the clinical management of asymptomatic disease-free third molars.

Prophylactic removal of impacted mandibular third molars: a systematic review and economic evaluation

BACKGROUND

Impacted third molars are third molars that are blocked, by soft tissue or bone, from fully erupting through the gum. This can cause pain and disease. The treatment options for people with impacted third molars are removal or retention with standard care. If there are pathological changes, the current National Institute for Health and Care Excellence guidance states that the impacted third molar should be removed.

OBJECTIVE

The objective of this study was to appraise the clinical effectiveness and cost-effectiveness of the prophylactic removal of impacted mandibular third molars compared with retention of, and standard care for, impacted third molars.

METHODS

Five electronic databases were searched (1999 to 29 April 2016) to identify relevant evidence [The Cochrane Library (searched 4 April 2016 and 29 April 2016), MEDLINE (searched 4 April 2016 and 29 April 2016), EMBASE (searched 4 April 2016 and 29 April 2016), EconLit (searched 4 April 2016 and 29 April 2016) and NHS Economic Evaluation Database (searched 4 April 2016)]. Studies that compared the prophylactic removal of impacted mandibular third molars with retention and standard care or studies that assessed the outcomes from either approach were included. The clinical outcomes considered were pathology associated with retention, post-operative complications following extraction and adverse effects of treatment. Cost-effectiveness outcomes included UK costs and health-related quality-of-life measures. In addition, the assessment group constructed a de novo economic model to compare the cost-effectiveness of a prophylactic removal strategy with that of retention and standard care.

RESULTS

The clinical review identified four cohort studies and nine systematic reviews. In the two studies that reported on surgical complications, no serious complications were reported. Pathological changes due to retention of asymptomatic impacted mandibular third molars were reported by three studies. In these studies, the extraction rate for retained impacted mandibular third molars varied from 5.5% to 31.4%; this variation can be explained by the differing follow-up periods (i.e. 1 and 5 years). The findings from this review are consistent with the findings from previous systematic reviews. Two published cost-effectiveness studies were identified. The authors of both studies concluded that, to their knowledge, there is currently no economic evidence to support the prophylactic removal of impacted mandibular third molars. The results generated by the assessment group's lifetime economic model indicated that the incremental cost-effectiveness ratio per quality-adjusted life-year gained for the comparison of a prophylactic removal strategy with a retention and standard care strategy is £11,741 for people aged 20 years with asymptomatic impacted mandibular third molars. The incremental cost per person associated with prophylactic extraction is £55.71, with an incremental quality-adjusted life-year gain of 0.005 per person. The base-case incremental cost-effectiveness ratio per quality-adjusted life-year gained was found to be robust when a range of sensitivity and scenario analyses were carried out.

LIMITATIONS

Limitations of the study included that no head-to-head trials comparing the effectiveness of prophylactic removal of impacted mandibular third molars with retention and standard care were identified with the assessment group model that was built on observational data. Utility data on impacted mandibular third molars and their symptoms are lacking.

CONCLUSIONS

The evidence comparing the prophylactic removal of impacted mandibular third molars with retention and standard care is very limited. However, the results from an exploratory assessment group model, which uses available evidence on symptom development and extraction rates of retained impacted mandibular third molars, suggest that prophylactic removal may be the more cost-effective strategy.

FUTURE WORK

Effectiveness evidence is lacking. Head-to-head trials comparing the prophylactic removal of trouble-free impacted mandibular third molars with retention and watchful waiting are required. If this is not possible, routine clinical data, using common definitions and outcome reporting methods, should be collected.

STUDY REGISTRATION

This study is registered as PROSPERO CRD42016037776.

FUNDING

This project was funded by the National Institute for Health Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 24, No. 30. See the NIHR Journals Library website for further project information.

Prevalence of distal surface caries in the second molar among referrals for assessment of third molars: a systematic review and meta-analysis

We conducted a systematic review of epidemiological studies to assess the prevalence of distal surface caries (DSC) in second molars adjacent to third molars. We searched the Cochrane Library, Lilacs, Embase, and Medline through Ovid^® (Wolters Kluwer) to retrieve English and non-English papers from inception to June 2016, and supplemented this with a search of the references and by tracking citations. Three reviewers contributed: one reviewed all the papers, and the other two divided the rest between them. They extracted data, completed structured quality assessments with a validated risk of bias tool for observational studies, and categorised the summary scores. The search yielded 81 records and 11 studies were analysed. The considerable methodological diversity meant that five were not eligible for inclusion in the quantitative synthesis. A meta-analysis of six studies on the prevalence of DSC and a subgroup analysis of three on various third-molar angulations were indicated. The overall pooled prevalence estimate calculated with a random-effects model was 23% (95% CI 2% to 44%) among patients. Prevalence subtotals were 20% (95% CI 5% to 36%) for prospective, and 15% (95% CI 5% to 36%) for retrospective studies among teeth. A subgroup analysis of three studies with 1296 patients (1666 molars) yielded a prevalence of DSC of 36% (95% CI 5% to 67%) for mesial impactions and 22% (95% CI 1% to 42%) for horizontal impactions. DSC was present in 3% of distally-inclined impactions, (95% CI 1% to 5%) and in 7% (95% CI 1% to 13%) of vertical third molars. The studies varied. The risk of bias was low in one and moderate in two. European studies suggested that DSC may be present in about one in four referrals for the assessment of third molars, and that the risk is considerably higher in those with convergent third molar impactions.

Distal caries of the second molar in the presence of a mandibular third molar - a prevention protocol

Objectives The objectives of the prospective study were to establish the prevalence of distal caries (DC) in the mandibular second molar and to assess the outcomes of these diseased teeth in our population. Further aims were to identify associated risk factors and to design a protocol for prevention.Methods Clinical and radiographic data from 210 consecutive patients were ascertained over a three-month period. The sample population included all patients who had been referred to a hospital oral surgery department for a lower wisdom tooth assessment.Results A total of 224 mandibular third molars were included and assessed. The prevalence of caries affecting the distal aspect of the second molar was 38% (n = 85) in this population. In 18% of patients there was evidence of early enamel caries. Fifty-eight percent of caries was managed with restorative treatment but 11% of patients required second molar extraction and 13% of patients required the removal of the second and third molars. The prevalence of distal caries was significantly higher in patients with partially erupted wisdom teeth positioned below the amelocemental junction (P <0.05) of the adjacent second molar and in patients who presented with mesioangular impactions (P <0.001). However there was no difference in dental health when comparing this group to the remaining study population (P = 0.354). The Pearson chi-square test and Pearson correlation coefficient were used to verify the association between the tested variables.Conclusion This study demonstrates that the eruption status, type of angulation and the nature of tooth contact between both molars are useful disease predictors which can be used to indicate the likelihood of a caries process occurring on the distal aspect of the second mandibular molar. If patients' third molar teeth are not removed then consideration needs to be given to prevention and regular monitoring.