Full-mouth versus partial-mouth recording in experimental gingivitis studies

Objectives: Clinical indices are the most widely used parameters for the assessment of plaque and gingivitis in clinical trials on oral hygiene products. However, a full-mouth recording of these indices is the most time consuming part of a study. Therefore, the aim of this investigation was to determine whether correlations exist between full-mouth and partial-mouth recording of plaque, gingivitis, and discoloration in experimental gingivitis (EG) studies. Methods: Two study populations who had different oral hygiene habits were investigated. Group A consisted of 79 dental students, group B included 78 subjects of a local population. During a 21-day EG study in parallel groups the subjects rinsed with 0.20 % or 0.06% chlorhexidine digluconate, amine fluoride/stannous fluoride, or a placebo. No oral hygiene was permitted. Gingival index (GI, Löe 1967), plaque index (PlI, Silness and Löe 1964), and discoloration index (Brecx et al. 1993) of the entire dentition were recorded. Parameters were scored two weeks before the start of the study, at baseline, and after 7, 14, and 21 days of rinsing. To test the association between full-mouth scores and "Ramfjord teeth" scores the Pearson correlation coefficients were calculated. Results: Statistically significant correlations between full-mouth and partial-mouth approaches were determined for GI, PlI, and DI. Correlations existed at all time points and in all mouthrinse groups. The majority of the correlations exceeded 0.90 but 0.80 in any case. When the means of the full-mouth recording were compared to the means of the "Ramfjord teeth", the differences were not higher than 0.07. Conclusions: Assessment of the "Ramfjord teeth" is as reliable as the full-mouth scoring in EG studies. The assessment of the "Ramfjord teeth" saves time for both participants and investigators, reduces costs, and results in a study simplification without distorting the outcome. The study was supported by GABA International AG. Keywords: clinical trial, experimental gingivitis, full-mouth recording, partial-mouth recording, mouthrinse, plaque index, gingivitis index, discoloration index