A cross-over Randomised Controlled Trial of selective pressure impressions for lower complete dentures.

OBJECTIVES: The objective of the research was to assess patient preference for a selective pressure impression technique for complete dentures by means of a Randomised Controlled Clinical Trial (RCT). METHODS: A literature review revealed no reported RCT's of selective pressure impressions for complete dentures. A cross-over, randomised, controlled, clinical trial was performed comparing selective pressure impressions with a placebo and an alternative method of re-distributing pressure. A sample size calculation yielded 65 patients. Sixty-nine patients, who had a superficial mental foramen on the lower denture bearing area, were recruited for the study. The primary outcome was the patients' preference of the dentures provided. The hypothesis under investigation was that one of the dentures would be preferred by the patients. RESULTS: Sixty-six participants completed the trial, 33 (50%) preferred the denture from the selective pressure impression, 19 (29%) the denture with traditional pressure relief, and 14 (21%) the placebo control. 95% confidence intervals showed that the preference for the selective pressure impression was greater than that of the other two techniques. The null hypothesis was rejected. CONCLUSIONS: The participants in this trial showed a preference for the denture constructed from the selective pressure impression technique, providing dentists with useful evidence for a clinical impression technique.

Are general dental practitioners effective in the management of non-apnoeic snoring using mandibular advancement appliances?

OBJECTIVE: This study assessed the effectiveness of general dental practitioners (GDPs) in the management of subjects with non-apnoeic snoring using a mandibular advancement appliance (MAA), following a one day training course. SUBJECTS AND METHODS: Sixty subjects suffering from simple, non-apnoeic snoring were treated by 15 GDPs, in three hospital centres, using a monobloc mandibular advancement appliance design. All GDPs attended a one day training course prior to the study which covered theoretical and practical training in the use of mandibular advancement appliances. Snoring and level of disturbance were assessed using a questionnaire completed by their sleeping partner before and after a three month treatment period. Daytime sleepiness was assessed by the patients using the Epworth sleepiness scale questionnaire (ESS) before and after a three month treatment period. In addition, patients completed an outcome questionnaire, to assess side-effects experienced from the MAA. RESULTS: A success rate of 48% (95% CI 0.35, 0.61) was achieved in partner-assessed snoring and disturbance levels, following a three month period of MAA treatment. The median ESS score reduced from 9 to 7.5 (95% CI 0, 3). General dental practitioners experienced problems during protrusive bite registrations, with 10% being judged inadequate. CONCLUSION: GDPs were not effective in the management of non-apnoeic snoring using a monobloc appliance after a one day training course. Further training and/or selection of a different design of appliance should be considered for GDPs to become highly competent in this area.

Statistical power for analyses of changes in randomized controlled trials.

Randomized controlled trials (RCTs) are widely recommended as the most useful study design to generate reliable evidence and guidance to daily practices in medicine and dentistry. However, it is not well-known in dental research that different statistical methods of data analysis can yield substantial differences in study power. In this study, computer simulations are used to explore how using different univariate and multivariate statistical methods of analyzing change in continuous outcome variables affects study power, and the sample size required for RCTs. Results show that, in general, analysis of covariance (ANCOVA) yields greater power than other statistical methods in testing the superiority of one treatment over another, or in testing the equivalence between two treatments. Therefore, ANCOVA should be used in preference to change score or percentage change score to reduce type II error rates.