Original article Distribution of biofilm on internal and external surfaces of upper complete dentures: the effect of hygiene instruction Helena de Freitas Oliveira Paranhos, Claudia Helena Lovato da Silva, Giovana Cherubini Venezian, Leandro Dorigan Macedo and Raphael Freitas de Souza Department of Dental Materials and Prosthodontics, Ribeira ˜o Preto School of Dentistry, University of Sa ˜o Paulo, Ribeira ˜ o Preto, Brazil Gerodontology 2007; 24; 162–168 Distribution of biofilm on internal and external surfaces of upper complete dentures: the effect of hygiene instruction Objectives: The purpose of this study was to evaluate biofilm distribution over internal and external surfaces of upper complete dentures. It was also aimed at assessing the effect of oral hygiene instructions before and after home use of a disclosing solution. Materials and methods: The sample consisted of 29 complete denture wearers whose upper prostheses were evaluated. Surface biofilm was disclosed by means of a 1% neutral red solution and quantified with regard to internal and external surfaces. Oral hygiene information was provided on an individual basis. During the second stage, an amount of disclosing solution was given for domestic use. Results: Internal and external surfaces presented a similar amount of biofilm, which was concentrated over the area of the posterior teeth area, palatal rugae and the internal vestibular incline of the distobuccal flange. This pattern was maintained during the study. However, overall amounts were reduced following denture hygiene information. The use of disclosing solution by subjects at home resulted in a further reduction. Conclusions: It was concluded that biofilm deposits were similar over assessed surfaces, regardless of the type of procedure but irregular areas presented greater amounts. Oral health instruction was effective in reducing the biofilm, in particular when associated with home use of a disclosing agent. Keywords: complete denture, oral hygiene, dental health education, biofilm. Accepted 18 February 2007 Introduction An effective biofilm control programme should be part of the treatment plan for every complete denture wearer. It has been reported that lower prevalence and intensity of denture stomatitis is related to good cleaning habits 1,2 . However, studies have revealed poor oral health amongst edentulous subjects 3–5 . This status can be explained by poor hygiene resulting from several factors such as insufficient information, decreased dexterity, shape of the prostheses and, in Brazil, the lack of specific products for denture cleaning 6,7 . Topographic distribution of biofilm over com- plete dentures is an important aspect to be con- sidered in oral hygiene and anatomical features of the base influence the retention of debris. Thus, awareness of areas on dentures that present greater retentive capacity can result in more effective removal of deposits by the patient 8 . As denture biofilm is transparent, it must be stained in order to be seen and in this context, the importance of disclosing dyes is evident. These dyes can be used in demonstrating hygiene, and in evaluating biofilm control habits of edentulous patients. Therefore, the use of dyes is advanta- geous in maintaining denture cleanliness, and thus a healthy mucosa 9 . The purpose of the present study was to describe the distribution of biofilm on the impression and polished surfaces of upper complete dentures. An assessment of the effect of patient information on denture hygiene with or without the domestic use of a disclosing solution was also carried out. Ó 2007 The Authors. Journal compilation Ó 2007 The Gerodontology Association and Blackwell Munksgaard Ltd 162 Gerodontology 2007; 24: 162–168