Surface enamel microhardness in nonclinical anticaries testing of fluoride toothpaste

Background This scoping review systematically evaluates the methodologies used in assessing enamel surface microhardness (SMH) in demineralization and remineralization research of anticaries toothpastes. The review identifies the parameters influencing SMH testing, highlights methodological variations, and proposes recommendations to standardize protocols and enhance reliability and suitability. Search Strategy The review followed Arksey and O'Malley's framework, using comprehensive database searches. Citation Sources Sources include MEDLINE, Embase, and Scopus. Study Selection Criteria In vitro and in situ studies evaluating the SMH of human enamel using fluoride toothpaste were included. Data Elements Included Evidence quality was assessed, and data extraction focused on testing parameters, sample characteristics, and methodological rigor. A total of 16,193 studies were screened, and 53 were included for full-text analysis. Remarkable methodological heterogeneity was observed. Only 21% of studies reported sample size calculations, and 17% used blinding. Screening methods for defects were inconsistent. Variations in SMH testing parameters were also notable. The Vickers indenter was the most commonly used. Loading forces varied widely, ranging from 25 through 500 g, with 50 g being the most applied. Most studies used a dwell time of 10 through 20 seconds. Variability in sample geometry and preparation techniques was identified, which can influence SMH values. Limited studies reported quality criteria such as statistical differences between groups (8%), underscoring the variability in reporting standards. Overall Conclusions The findings reveal substantial gaps in methodological rigor and consistency across studies, emphasizing the need for standardized protocols in enamel SMH testing. This review provides insights for future research to validate alternative anticaries testing procedures applicable to regulatory testing or other standardized clinical testing.