Interproximal contact types of primary molars based on the OXIS classification: a cross-sectional study in Turkiye

The aim of this study was to investigate the different interproximal contact areas of primary molars, as defined in the OXIS classification. This study evaluated 1033 contact areas of caries-free primary molars in 422 children aged 3–8 years. During clinical examinations, contact types were recorded according to the OXIS classification as “O” (open), “X” (point), “I” (straight), and “S” (curved). Contact types were analyzed in relation to age, gender, and location. Data were assessed using descriptive statistical methods, chi-square tests and Fisher’s exact test. A total of 422 patients participated in the study, including 225 girls and 197 boys. The most frequently observed contact type was “I” (73.1%), while the least was “O” (5.9%). These findings were consistent across both genders. When age groups were evaluated separately, type “I” was the most prevalent in all age groups. When dental arches were analyzed independently, “I” type contact was the most common in all quadrants. The least frequent contact type in the maxilla was “O,” whereas in the mandible it was “S”. According to the OXIS classification, type ‘‘I’’ was the most frequently observed interproximal contact type among primary molars in the study sample. The high prevalence of closed contacts (94.1%) underscores the importance of interproximal plaque control in this age group. However, further studies using the OXIS classification are needed.