A cross-over Randomised Controlled Trial of selective pressure impressions for lower complete dentures T.P. Hyde a, *, H.L. Craddock a , A. Blance b , P.A. Brunton a a Operative Dentistry, Leeds Dental Institute, Clarendon Way, University of Leeds, Leeds LS2 9LU, United Kingdom b Division of Biostatistics, Leeds Institute of Genetics, Health & Therapeutics, Clarendon Way, University of Leeds, Leeds LS2 9JT, United Kingdom 1. Introduction The dental academic literature has many papers, case histories and textbooks written on the subject of impressions for complete dentures. Four broad concepts for impressions have been described: Muco-displacing, 1 Mucostatic, 2,3 Selec- tive Pressure 4–8 and Functional 9,10 Impressions. These im- pression techniques have been suggested and developed to record the denture bearing tissues in various states of displacement, and to manage particular clinical situations. The different states of tissue displacement are said to be achieved by variations in pressure within the impression. The evidence for pressure variation with impressions comes from the laboratory experiments by Frank, 11 Komiyama, 12 Masri, 13 Al-Ahmad 14 and Hyde 15 who have all have shown variation in the pressure of impressions in vitro. However, the level of in vivo evidence and in particular the clinical evidence for particular impression techniques is poor and needs careful consideration. Within the prosthodontic literature, there is a paucity of high quality evidence in the form of Randomised Controlled journal of dentistry 38 (2010) 853–858 article info Article history: Received 11 May 2010 Received in revised form 7 July 2010 Accepted 8 July 2010 Keywords: Randomised Trial Denture Impression RCT abstract 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. # 2010 Elsevier Ltd. All rights reserved. * Corresponding author. Tel.: +44 0113 343 8515; fax: +44 0113 343 6236. E-mail address: T.P.Hyde@Leeds.ac.uk (T.P. Hyde). available at www.sciencedirect.com journal homepage: www.intl.elsevierhealth.com/journals/jden 0300-5712/$ – see front matter # 2010 Elsevier Ltd. All rights reserved. doi:10.1016/j.jdent.2010.07.003