AIM: To evaluate the occurrence of supra-gingival calculus in children aged 6-9 years with disuse conditions such as: presence of dental pain, open-bite or erupting teeth. METHODS: A cohort of 327 children aged 7.64[+ or -]2.12 (range: 6-9) years (45% girls) were screened for presence of supra-gingival calculus in relation to open bite, erupting teeth and dental pain. Presence of dental calculus was evaluated dichotomically in the buccal, palatinal/lingual and occlusal surfaces. Plaque index (PI) and gingival index (GI) were also evaluated. RESULTS: Supra-gingival calculus was found in 15.9% of the children mainly in the mandibular incisors. Children aged 6-7 years had a higher prevalence of calculus as compared to children aged 7-8 years (23% vs. 13.5%, p = 0.057) or 8-9 years (23% vs. 12.4%, p = 0.078), respectively. No statistical relation was found between plaque and gingival indices and presence of calculus. The prevalence of calculus among children with open-bite was significantly higher than that of children without open-bite (29.4% vs. 10.7%, p = 0.0006, OR = 3.489). The prevalence of calculus among children with erupting teeth in their oral cavity was higher than that of children without erupting teeth (17.7% vs. 9%, respectively, p = 0.119). No statistical correlation was found between presence of dental pain and calculus (15.4% vs. 15.9%; p = 0.738). CONCLUSION: Accumulation of calculus in children aged 6-10 years was found mainly in the mandibular incisors, decreased with age and was correlated with open-bite. Key words: Open-bite, disuse, prevention, plaque, scaling.