Objective: To critically analyse the formation, composition, ethnic variations and pathogenic potential of subgingival calculus in comparison with supragingival calculus.
Data sources: Using CD-ROM and index medicus, scientific papers relating to subgingival calculus or subgingival and supragingival calculus written in the English language since 1960 were considered, with the emphasis on more recent articles.
Study selection: Studies were selected for their relevance and contemporary nature re:composition and formation of dental calculus and comparisons of ethnic groups with regard to dental calculus, especially subgingival calculus. Some similar studies were not included.
Data extraction: Abstracts of studies were kept brief unless particularly important to the review. Population, methodology, statistics and accurate conclusions were used as important guides to the quality and validity of studies.
Data synthesis: Similarities and differences between supragingival and subgingival calculus in composition and formation were shown. Different morphological types of subgingival calculus were demonstrated. There was evidence for an association between calculus formation and ethnicity with regard to supragingival and subgingival calculus, and an association between subgingival calculus composition and ethnicity was indicated.
Conclusions: An association between ethnicity and subgingival calculus formation and composition was found. Further research into the reasons for these ethnic differences in dental calculus and the role of the mineral constituents especially of subgingival calculus would be valuable.