Variations in Primary Molar Contact and Approximal Caries in Children: A Three-Year Prospective Cohort Study.

To evaluate the association between the contact areas of primary molar teeth and approximal caries after three years of observation. This prospective cohort study included 1,119 caries-free children, aged three to four years, from Puducherry, India. At base- line, 4,476 contacts were assessed using the OXIS criteria, which denotes O for open contact and X, I, and S for closed contacts. X contact represents a point contact, I is a straight contact, and S is a curved contact. Two calibrated dentists measured dental caries at one-year intervals following the International Caries Detection and Assessment System for three years. Poisson regression analysis with a multilevel approach was used to determine the association between contact type and approximal caries. Of 3,848 contacts observed at the end of three years, 499 (13 percent) were carious. The adjusted analysis revealed a significant association between contact type and approximal caries (P<0.05). The risk ratios for the development of approximal caries were 2.3 for X-type contacts (0.5 to 11.4, P=0.307), 12.7 for I-type (4.1 to 39.6, P<0.05), and 22.5 for S-type (7.2 to 70.6, P<0.05) when compared with O-type. Compelling evidence suggests that variations in contacts between teeth are significant in the development of approximal caries. The S-type contact is the most susceptible to approximal caries, followed by the I-type.