The effects of illumination and focal distance on light-induced fluorescence images in vitro.

When using quantitative light-induced fluorescence a number of factors can influence illumination level. The purpose of this study was to investigate, using a high-resolution camera and fibre-optic light source, the impact of illumination level and focal distance on common quantitative light-induced fluorescence outcomes. Twenty-four extracted teeth were examined using 6 illumination levels and 4 focal distances. Analysis was conducted using multiple linear regression models fitted to log DeltaQ, log DeltaF and log area with clustering of teeth and robust standard errors. Separate models were used for the different light and focal levels. The regression coefficients were significant for both DeltaQ and DeltaF but not area. Despite the significant regressions the actual effect was very small, and unlikely to confound clinical trial or practice results.

Potassium nitrate toothpaste for dentine hypersensitivity.

BACKGROUND: Dentine hypersensitivity may be defined as the pain arising from exposed dentine, typically in response to external stimuli, and which cannot be explained by any other form of dental disease. Many treatment regimes have been recommended over the years, and in recent years particular attention has been focused on toothpastes containing potassium nitrate. OBJECTIVES: To compare the effectiveness of potassium nitrate containing toothpastes with placebo toothpastes in reducing dentine hypersensitivity. SEARCH STRATEGY: The following databases were cross searched via the database host DIALOG: MEDLINE, EMBASE, ELSEVIER BIOBASE, BIOSIS PREVIEWS, CAB HEALTH, SCI SEARCH, CURRENT CONTENTS until 1 April 2000. The specialised Cochrane Oral Health Group Trials Register was also searched. Bibliographies of clinical studies and reviews identified in the electronic search were checked for studies published outside the electronically searched journals. SELECTION CRITERIA: Randomised clinical trials (RCTs) in which the effect on dentine hypersensitivity of potassium nitrate toothpastes were tested against non-potassium nitrate containing placebo toothpastes. DATA COLLECTION AND ANALYSIS: Two of the reviewers independently recorded the results of the included trials using a specially designed chart. Sensitivity was assessed by using thermal, tactile, air blast, and subjective methods. The quality of all RCTs, that fulfilled the inclusion criteria, was acceptable with Jadad scores ranging from 3 to 4 (Jadad 1998). MAIN RESULTS: Out of the eight studies that initially fulfilled the criteria to be included in the review, four studies did not present mean and standard deviations and could thus not be included in the meta-analysis. Three of these did not show an effect on any of the measurements of dentine hypersensitivity, while one did. Four studies were included in the meta-analysis which showed statistically significant effect of potassium nitrate toothpaste on air blast and tactile sensitivity, e.g. the meta analysis of air blast sensitivity showed a standardized mean difference in sensitivity score of -1.51 (95% CI: -2.09 to -0.94) in favour of treatment. The subjective assessment failed to show a significant effect at the six to eight week assessment. REVIEWER'S CONCLUSIONS: No strong evidence is available supporting the efficacy of potassium nitrate toothpaste for dentine hypersensitivity.