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Health Technol Assess.2020 Jun;24(30):1-116. doi: 10.3310/hta24300.


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

  • Juliet Hounsome
  • Gerlinde Pilkington
  • James Mahon
  • Angela Boland
  • Sophie Beale
  • Eleanor Kotas
  • Tara Renton
  • Rumona Dickson
PMID: 32589125 PMCID: PMC7336222. DOI: 10.3310/hta24300.



インパクトを受けた第三大臼歯は、第三大臼歯が軟組織や骨によって、歯肉から完全に噴出することができなくなっている状態です。これは痛みや病気の原因となります。インパクトのある第三大臼歯の人の治療法は、標準的な治療による抜歯か保定です。病理的な変化がある場合は、現在のNational Institute for Health and Care Excellenceのガイダンスでは、衝撃を受けた第三大臼歯を除去すべきであるとされています。

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.


関連するエビデンスを特定するために、5つの電子データベースを検索した(1999年~2016年4月29日)[The Cochrane Library(2016年4月4日検索、2016年4月29日検索)、MEDLINE(2016年4月4日検索、2016年4月29日検索)、EMBASE(2016年4月4日検索、2016年4月29日検索)、EconLit(2016年4月4日検索、2016年4月29日検索)、NHS経済評価データベース(2016年4月4日検索)]。衝撃を受けた下顎第三大臼歯の予防的除去を保持と標準治療とで比較した研究、またはどちらのアプローチからの転帰を評価した研究が含まれた。考慮された臨床転帰は、留置に関連する病理学、抜歯後の術後合併症、治療の副作用であった。費用対効果のアウトカムには、英国のコストと健康関連のQOL(生活の質)が含まれていた。さらに、評価グループは、予防的摘出法の費用対効果を留置および標準治療と比較するために、de novo経済モデルを構築した。

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.


この研究はPROSPERO CRD42016037776として登録されています。

STUDY REGISTRATION: This study is registered as PROSPERO CRD42016037776.


このプロジェクトは、国立衛生研究所(NIHR)の健康技術評価プログラムから資金提供を受けており、その全文は、Vol.24, No.30に掲載される予定です。NIHR Journals Libraryのウェブサイトで、プロジェクトの詳細情報をご覧ください。

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

第三大臼歯は、一般的に親知らずとして知られていますが、通常、若年期(18~24歳)には問題なく歯茎から生えてきます。しかし、いくつかのケースでは、他の歯、歯茎、または骨によって、それらがうまく配置されていないか、または妨害されているため、それらが噴火することができません。このような場合は「インパクテッド」と呼ばれます。歴史的に、歯科医はしばしばこれらの歯を除去することを推奨していました。これは「予防的」抜歯と呼ばれています。2000年には、国立医療技術研究所(National Institute for Health and Care Excellence)がこの慣習を見直し、人に迷惑をかけない場合には、これらの歯を除去すべきではないと推奨しています。多くの歯科医師や口腔外科医は、これらの歯を人生の後半で除去することはより困難であり、人生の後半で除去した場合、患者にとってより多くの合併症があると信じて、この決定に反対してきました。私たちのレビューグループは、衝撃を受けた第三大臼歯の予防的抜歯について、利用可能な臨床的有効性と費用対効果のエビデンスを系統的にレビューした。このレビューでは4件の臨床研究が確認されたが、いずれも第三大臼歯の予防的抜歯に強いエビデンスを提供するものではなかった。これらの知見は、以前の9件のレビューと同様である。また、この方法の費用対効果に関する研究はほとんど報告されておらず、3件の研究しか確認されていません。抜歯率と下顎第三大臼歯の衝撃を受けたままにしている人が経験する症状に関する利用可能なエビデンスをもとに、予防的抜歯を推奨する場合の費用対効果を評価するための探索的経済モデルを構築し、見守りを推奨する場合の費用対効果と比較しました。このモデルの結果から、予防的な抜歯は見守りよりも費用がかかるが、生活の質の改善につながることが示唆された。2つの戦略に関連する費用とQOLの測定値を比較すると、結果として得られた統計量は、QOL調整後の生活年数あたり11,741ポンドであり、これはおそらくNHSにとってお得であると思われる。

Third molars, commonly known as wisdom teeth, may come through the gum (erupt) without any problems, usually during young adulthood (aged 18–24 years). However, in some cases they are unable to erupt because they are poorly aligned or obstructed by other teeth, gums or bone. They are then referred to as ‘impacted’. Historically, dentists often recommended that these teeth be removed, so as not to cause problems later in life. This is referred to as ‘prophylactic’ removal. In 2000, the National Institute for Health and Care Excellence reviewed this practice and recommended that these teeth should not be removed if they are not bothersome to the person. Many dentists and oral surgeons have disagreed with this decision, believing that it is more difficult to remove these teeth later in life, and that there are more complications for the patient if they are removed later in life. Our review group carried out a systematic review of the available clinical effectiveness and cost-effectiveness evidence of the prophylactic removal of impacted third molars. The review identified four clinical studies, none of which provided strong evidence for or against the prophylactic removal of these teeth. These findings are similar to those of nine previous reviews. There is also very little research reported that relates to the cost-effectiveness of the procedure, with only three studies identified. With the available evidence on the rates of extraction and the symptoms experienced by people who keep their impacted mandibular third molar, we built an exploratory economic model to assess the cost-effectiveness of recommending prophylactic removal compared with that of recommending watchful waiting. Results from the model suggested that a prophylactic removal strategy costs more than a watchful waiting strategy, but leads to improvements in quality of life. When the costs and quality-of-life measures that are associated with the two strategies are compared, the resulting statistic is £11,741 per quality-adjusted life-year gained, which would probably be good value for money for the NHS.