Abrasiveness of an air-powder polishing system on root surfaces in vitro.

OBJECTIVE: The purpose of this study was to evaluate the abrasiveness of a new air polisher on root surfaces. METHOD AND MATERIALS: Fifty extracted human teeth were air polished for 5 seconds. RESULTS: All root surfaces showed a circular defect visible with the naked eye. Scanning electron microscope examination showed smooth crater walls and a few open dentin tubules, but most seemed to be obliterated. Laser profilometry of the exposed areas revealed defects with an average depth of 484 microns, whereas the unexposed root surfaces showed irregularities with an average depth of 323 microns. The depths of the abraded areas were evaluated in relation to the values for the unexposed surfaces, and an average depth of 161 microns was found. The difference between the exposed and unexposed surfaces was statistically significant. CONCLUSION: The present study indicates that the air polisher has a strong abrading effect on exposed root surfaces and should therefore be used with caution on patients with gingival retractions.

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.