Effect of calcium hydroxide on fracture resistance and microhardness of dentin in human teeth: A systematic review

Aim: Calcium hydroxide to date is a widely used intracanal medicament during endodontic treatment. Long duration of exposure of dentin to calcium hydroxide may influence the fracture resistance and microhardness of dentin thereby affecting the tooth. The aim of this review was to identify and systematically analyze the effect of calcium hydroxide on fracture resistance and microhardness of dentin in human teeth. Methods: A PubMed and Scopus search was performed using keywords 'fracture resistance' and 'microhardness' along with Medical Subject Heading (MeSH) terms 'Calcium hydroxide' and 'dentin' and 'tooth' till 12th March 2022. The reference list of each selected article was also explored to identify additional articles. An inclusion criteria was set that had to be met by each study for it to be selected for the review. Only articles written in English language were included in this systematic review. The review was conducted according to the PRISMA checklist. Results: Ten in-vitro studies that fulfilled the inclusion criteria were included in this review. The findings of majority of studies showed that an exposure duration of more than one month to calcium hydroxide decreased the fracture resistance and microhardness of dentin thereby affecting the strength of the tooth. Further, one week of exposure to calcium hydroxide did not show any significant change in fracture resistance. Conclusion: Based on the analysis of the studies included in this review, it can be concluded that increased duration of exposure of dentin to calcium hydroxide negatively affects the fracture resistance and microhardness, thereby weakening the tooth.