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ABSTRACT PURPOSE OF INVESTIGATION The study was undertaken to identify the least costly, most effective and most cost-effective management strategy for asymptomatic, disease free mandibular
third molars. METHODS AND PATIENTS A decision tree model of the outcomes of mandibular third molar retention and removal was constructed. Probability data for possible outcomes were obtained
from a comprehensive literature review and entered into the decision tree. The cost to the NHS in treating each outcome was calculated. 100 patients attending the oral surgery clinics,
University of Wales Dental Hospital rated the effect of each outcome on their own life. The cost and effectiveness data for each outcome were entered into the decision tree and the analyses
were conducted by 'folding back' the decision tree based on the probabilities. MAIN FINDINGS Mandibular third molar retention was less costly (£170), more effective (69.5
effectiveness units on a 100 point scale) and more cost-effective (£2.43 per unit of effectiveness) than removal (£226, 63.3 and £3.57 respectively). These findings were sensitive to changes
in the probability of pericoronitis, periodontal disease and caries. PRINCIPAL CONCLUSIONS Mandibular third molar retention is less costly to the NHS, more effective for the patient and
more cost-effective to both parties than removal. However, should the likelihood of developing pericoronitis, periodontal disease and caries increase substantially then removal becomes the
more cost-effective strategy. You have full access to this article via your institution. Download PDF SIMILAR CONTENT BEING VIEWED BY OTHERS HISTORICAL ASPECTS ABOUT THIRD MOLAR REMOVAL
VERSUS RETENTION AND DISTAL SURFACE CARIES IN THE SECOND MANDIBULAR MOLAR ADJACENT TO IMPACTED THIRD MOLARS Article 24 February 2023 HALL TECHNIQUE: IS IT SUPERIOR IN SUCCESS AND SAVINGS TO
CONVENTIONAL RESTORATIONS? Article 18 December 2020 PATIENT PREFERENCE FOR THE MANAGEMENT OF MANDIBULAR THIRD MOLARS WITH MESIO-ANGULAR AND HORIZONTAL IMPACTIONS Article 07 February 2025
MAIN The indications for the removal of mandibular third molars have been the subject of a great deal of debate. In the past, many dentists and surgeons have recommended that asymptomatic
mandibular third molars should be removed to prevent future disease.1,2,3 Many others have expressed the opposite view. Published reviews of the risks and benefits of mandibular third molar
management have concluded that prophylactic removal is unjustified.4,5 Decision and cost-effectiveness analyses have strongly supported the appropriateness of retention of asymptomatic,
disease free third molars.6,7,8 However, these studies have rarely taken account of the patients' perspective or health service costs. As health care evolves towards a patient-centred
service, it is increasingly important to consider the patient's perspective in health care decisions.9 Additionally, decisions must be made concerning the maximisation of effective
resource allocation. A method of quantifying the relative costs, effectiveness and cost-effectiveness of particular treatment options is decision analysis. This method depends on clinical
knowledge (probability of outcomes) and values attached to different outcomes (patient utilities and health service cost). It permits both objective data and subjective personal preferences
to play a part in the decision process. This is consistent with how medical decisions are actually made.10 Decision analysis was first described more than three decades ago.11 It arose from
the disciplines of economics, statistics, and psychology and in the case of clinical decision analysis, epidemiology and clinical informatics. Since the 1970s, decision analysis has
increasingly been applied to complex medical decisions12 in clinical, financial and research settings.13 The increased use of decision analysis in medicine and dentistry6,8 possibly reflects
the increasing importance of economic costs and quality of health care provision. Tulloch _et al_. have stated that 'Although performing a detailed analysis for every mandibular third
molar management decision may appear complex and time-consuming, an analysis of well-defined outcomes that occur frequently and where there are both uncertainties and risks would be
useful'.19 This study is based on this recommendation, a decision analysis was conducted to identify the least costly, most effective and most cost-effective management strategy for
asymptomatic, disease-free third molars from both the health care provider and patient perspective. METHOD The construction of the decision tree and determination of the probability, cost
and effectiveness data was carried out in phases. PHASE 1 CONSTRUCTION OF THE DECISION TREE AND DETERMINATION OF THE PROBABILITY DATA. The various outcomes of lower third molar retention and
removal, together with their incidences were obtained from a comprehensive computerised (Medline) and manual search of the medical literature (1966 to 1998). The detailed outcomes were
structured within their own sub-trees, for example with or without pain (Appendix 1). The probability of each outcome was the mean incidence reported from all of the relevant literature. The
rates were expressed as a proportion of one relative to the other outcomes within the sub-tree. Collectively, this information formed the basis of the decision tree, which was constructed
using decision analysis software20 (Appendix 1). The decision tree did not include an analysis of differences in surgical morbidity with age or changes in increase of disease with age.
Evidence available in relation to these issues is scarce, but such evidence as is available suggests that surgical morbidity does not increase with age.21 Therefore, these values were not
incorporated into the decision analysis. PHASE 2: DETERMINATION OF COST DATA Cost was measured in terms of direct economic cost in an NHS hospital and incorporated consumables, staff costs,
overheads and equivalent annual costs. The strategy used to calculate these can be seen in Appendix 2. The costs for third molar removal (including anaesthetic costs) and retention were
calculated to obtain a total cost given a particular outcome (Tables 1 and 2). PHASE 3: DETERMINATION OF EFFECTIVENESS DATA Effectiveness data were obtained using a questionnaire adapted and
modified from research conducted by Armstrong _et al_.22 The questionnaire consisted of twenty-two scenarios, describing in everyday language all of the various outcomes identified in the
literature, for example 'A wisdom tooth erupts at the back of your mouth. Every six weeks or so you experience a few days of aching pain around the tooth and the gum feels
swollen', and 'After the extraction you experience pain and your face and mouth are swollen'. Fourteen of the scenarios represented the possible health outcomes following
third molar removal (Table 1) and eight scenarios represented the outcomes of retention (Table 2). Accompanying each scenario was a VAS, 100mm in length. The end points of the VAS were
'Things could not be worse' (0mm) and 'I would not be bothered at all' (100mm). One hundred and two consecutive patients were invited to rate the outcomes after they had
completed a consultation in the oral surgery clinic, University of Wales Dental Hospital; however, two refused due to lack of time. As part of normal treatment planning, patients had been
informed of all the possible outcomes of removal by the clinician. In addition, to standardise this information, an information leaflet23 was given to the patient to read at the end of the
consultation. Before completing the questionnaire, the patients were asked to read each of the scenarios. This allowed them to become familiarised with the scope of outcomes. Each patient
then re-read the scenarios and placed a cross on the VAS at a point they felt represented how they would feel if they experienced each of the scenarios. The patients were allowed as much
time as they required to complete the questionnaire. The cross made by each patient on the VAS for each scenario was measured to the nearest millimetre and constituted the measure of
effectiveness. The mean effectiveness scores were then calculated (Table 3). PHASE 4: DECISION ANALYSIS NHS procedure costs and mean effectiveness scores were entered into their respective
terminal nodes, or outcomes on the tree. Collectively, these values were 'folded back'. This is a decision analysis procedure that takes into consideration the probability of each
outcome when determining the average cost, effectiveness and cost-effectiveness of mandibular third molar retention and removal. In addition, the various values were subjected to sensitivity
analyses, which allowed the investigation of how changes to the various values could alter the most cost-effective strategy. RESULTS The National Health Service procedure cost of outcomes
following mandibular third molar management is shown in Tables 1 and 2 and Appendix 3. The average National Health Service procedure cost for mandibular third molar retention (£170) was less
than surgical removal (£226) resulting in a marginal cost of £56 (Table 4). The effectiveness of mandibular third molar management was rated as being greater for third molar retention
(69.5) than for removal (63.3) giving a marginal effectiveness of -6.2 (Table 4). Taking into consideration both the costs and effects, mandibular third molar retention (£2.43 per unit of
effectiveness) was more cost-effective than removal (£3.57 per unit of effectiveness). It thus follows that the strategy of removal was less cost effective over the whole range of cost
compared with the strategy of third molar retention (Table 4). Sensitivity analyses revealed that the model was only sensitive to alteration of the probability values for pericoronitis,
periodontal disease and unrestorable caries in the second molar. They had threshold values of 0.40, 0.17 and 0.22, respectively. The threshold values indicate the point at which the most
cost-effective strategy for an asymptomatic mandibular third molar would alter from retention to removal. For example, if for a particular third molar, the probability of developing
pericoronitis exceeded 40% then it would be more cost effective to remove the tooth than to adopt a conservative approach. DISCUSSION AND CONCLUSIONS Cost, effectiveness and
cost-effectiveness analyses indicated that third molar retention was less costly to the NHS within the Hospital Dental Service, more effective for the patient and more cost-effective than
removal. Although the costs are specific to the HDS, these findings support the findings of previous research suggesting that third molar retention is the optimal management for
asymptomatic, disease free mandibular third molars.4,5,6,7,8 It is appropriate to consider the extent to which these results would translate to general practice where different costs would
apply. Potentially, more efficient cost control in practice might make the surgical treatment of patients with mild low grade disease more appropriate. However, the optimal treatment for
pathology free teeth would not alter since, on clinical grounds alone, they are best treated conservatively. The findings also suggest that there is only a cost saving or health gain in
removing asymptomatic, pathology-free mandibular third molars when there is a substantially increased risk of developing pericoronitis, periodontal disease and caries. Should the chance of a
patient developing one of these three diseases be greater than the threshold value identified in this study then removal becomes the more cost-effective strategy. Certain populations are at
greater risk of developing pericoronitis/periodontal diseases such as smokers.23,24 An additional concern is that the probability values used for this study may be underestimated. The range
of reported incidences in the literature suggests that this is possible in some patient groups as the maximum reported probabilities compare with the probabilities that would change the
optimal strategy.25,26,27,28,29 The conclusions drawn from decision analyses depend upon the quality of the information upon which they are based. In this instance, the sources of
probability data were of concern as there was a wide range of reported incidences for each outcome suggesting that there were both variations in methodology and biases in results. Ideally,
randomised-controlled trials or prospective, longitudinal research needs to be conducted to provide evidence that is more conclusive. The benefit of incorporating NHS cost and patient
perceived effects when evaluating mandibular third molar management options is that resources can be apportioned so that treatment that does not yield a health gain can be avoided.8 Cost and
effectiveness data collection is straightforward. This would facilitate analyses on a national basis and across various clinical settings. This type of analysis also provides a clearer
insight into the economic implications of high volume, high cost procedures, where small changes in treatment may result in large gains in terms of financial and opportunity cost. This study
has highlighted the dynamics of decision making in relation to one high volume surgical procedure. The apparent similarities between the perceived and economic impact of mandibular third
molar management options implies that there is some agreement between the patient and the NHS when it comes to developing appropriate criteria for treatment interventions. The likelihood of
developing pericoronitis, periodontal disease and unrestorable caries are the only factors that may challenge the philosophy that prophylactic removal should be avoided. Until more knowledge
is gained about the risks of developing these, non-surgical management of asymptomatic mandibular third molars remains the most cost-effective strategy for the NHS. REFERENCES * Laskin D M
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AUTHORS AND AFFILIATIONS * Department of Oral Surgery, Clinical Decisions Research Group, Medicine and Pathology, University of Wales College of Medicine Dental School, Heath Park, CF4 4XY,
Cardiff Michelle J Edwards, Mark R Brickley, Rebecca D Goodey & Jonathan P Shepherd Authors * Michelle J Edwards View author publications You can also search for this author inPubMed
Google Scholar * Mark R Brickley View author publications You can also search for this author inPubMed Google Scholar * Rebecca D Goodey View author publications You can also search for this
author inPubMed Google Scholar * Jonathan P Shepherd View author publications You can also search for this author inPubMed Google Scholar ADDITIONAL INFORMATION REFEREED PAPER APPENDICES
APPENDIX 1 APPENDIX 2 APPENDIX 3 RIGHTS AND PERMISSIONS Reprints and permissions ABOUT THIS ARTICLE CITE THIS ARTICLE Edwards, M., Brickley, M., Goodey, R. _et al._ The cost, effectiveness
and cost effectivenes of removal and retention of asymptomatic, disease free third molars. _Br Dent J_ 187, 380–384 (1999). https://doi.org/10.1038/sj.bdj.4800285 Download citation *
Received: 14 January 1999 * Accepted: 23 July 1999 * Published: 09 October 1999 * Issue Date: 09 October 1999 * DOI: https://doi.org/10.1038/sj.bdj.4800285 SHARE THIS ARTICLE Anyone you
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