Management of Unerupted and Impacted Third Molar Teeth
Section 1: Introduction

1.1 Background

Third molars generally erupt between the ages of 18 and 24 years, although there is wide variation in eruption dates. One or more third molars are absent in approximately 25% of adults2, 3, 4, 5 but they may still be present in the elderly, otherwise edentulous, patient.

The prevalence of unerupted third molars varies widely and is influenced by age, gender and ethnicity. The failure of eruption of third molars is a very common condition3, 6, 7, 8 and the extraction of impacted third molar teeth is one of the most frequent surgical procedures carried out in the NHS. It has been reported that a significant proportion of those on oral and maxillofacial surgery waiting lists are awaiting third molar removal.9, 10, 11

1.2 The need for a guideline

Surgical procedures for extraction of unerupted third molar teeth are associated with significant morbidity including pain and swelling, together with the possibility of temporary or permanent nerve damage, resulting in altered sensation of lip or tongue.12 There appears to be substantial variation in management and it has been reported that conservative treatment with more rigorous adherence to specific indicators for removal would reduce surgical cases by up to 60%.13 A recent review by the NHS Centre for Reviews and Dissemination concluded that 'there appears to be little justification for the removal of pathology-free impacted third molars.' 3

A number of guidelines on this topic have been produced in recent years. The most recent document, produced by a working party of the Faculty of Dental Surgery of the Royal College of Surgeons of England, was published during the development of this SIGN guideline.7 The members of the SIGN guideline development group are grateful for the co-operation offered by the Royal College of Surgeons of England working party and have benefited from the information contained in their document. The SIGN guideline development group considered carefully whether a further guideline was necessary, and concluded that there was scope to build on existing guidelines by using SIGN methodology to develop recommendations based upon the best evidence available.

1.3 Aim of the guideline

The aim of this national guideline is to assist individual clinicians, hospital departments, hospitals and commissioners of health care to produce local guidelines for the identification of patients who might benefit most from removal of unerupted third molar teeth and those for whom removal is not necessary.

1.4 Development of the guideline

The SIGN guideline development methodology involves an extensive review and appraisal of the existing literature (see Annex 1).14 A similar exercise carried out by the NHS Centre for Reviews and Dissemination found that there were no randomised controlled trials to compare the long term outcome of early removal with the deliberate retention of pathology-free third molars, and a dearth of relevant good quality primary studies.3, 15 The systematic literature review carried out by the SIGN third molar guideline development group confirmed this lack of evidence from well-designed randomised controlled trials.

The available evidence is generally from non-experimental descriptive studies (evidence level III) and the recommendations, although based on the best evidence available, are therefore mostly graded as B or C. However, it should be emphasised that this grading relates only to the strength of supporting evidence for each recommendation, and not to the importance of the recommendation.

1.5 Definitions and terminology

Recently published guidelines have included definitions7, 16 and for the purposes of this guideline minor modifications of the previously reported definitions have been introduced:

Throughout the guideline the term third molar refers to unerupted and partially erupted third molar teeth which may or may not be impacted.

The general principles in the guideline apply to both upper and lower third molar teeth, but surgical management of upper third molars is in general much less complex and most of the difficulties apply to lower third molars. Upper wisdom teeth cause less discomfort, are more likely to erupt, and are simpler to remove unless unerupted and encased in bone. Removal of upper third molars results in far less postoperative morbidity, and general anaesthetics are rarely required.

Wherever possible, the guideline development group have employed the most commonly used terminology, e.g. the term local anaesthesia is used in place of local analgesia.

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