[Occlusal contact of primary dentition at intercuspal position in children with individual normal occlusion]

Objective: To record occlusal contact of primary dentition at maximal intercuspal position in children with individual normal occlusion. Methods: A total of 57 children were recruited from patients of the Department of Pediatric Dentistry, Peking University School and Hospital of Stomatology. Inclusion criteria were that the subjects were 3-5 years old with no visually detectable caries or pupal and periapical diseases, had complete primary dentition, had individual normal occlusion, had normal function of craniofacial system, were medically healthy, could cooperate with sampling and had obtained written informed consent from the parents or guardians. Finally, forty-seven children aged 3 to 5 years old were enrolled, including 24 males and 23 females. The age, height and weight of all subjects were (4.1±0.7) years old (ranging 3.0-5.8 years old), (103.7±7.2) cm (ranging 90-120 cm) and (17.1±2.5) kg (ranging 12.5-22.5 kg), respectively. Occlusal abilities such as occlusal contact area, average bite pressure, maximum bite pressure, maximum bite force and occlusal balance were measured with Dental Prescale Ⅱ system. Results: Maximum bite force and occlusal contact area at intercuspal position in children with primary dentition were (567.40±223.84) N (ranging 226.7-1 154.6 N) and (18.56±6.54) mm² (ranging 8.4-41.2 mm²), respectively. There was a significantly strong correlation between maximum bite force and occlusal contact area (r=0.954, P<0.01). Height and weight of children were also positively correlated with their maximum bite force (r=0.397, P=0.022 and r=0.453, P=0.008, respectively). Maximum occlusal bite force and contact occlusal area of boys [(651.80±224.34) N and (20.77±6.97) mm²] were significantly higher and larger than those of girls [(479.34±190.45) N and (16.25±5.27) mm²] (P<0.05). Thirty-two of all 47 children had one occlusal contact point with maximum bite pressure, mostly locating within the primary molar region. Bite forces of anterior and posterior teeth of primary dentition were (124.12±56.99) N and (450.11±205.09) N, respectively, about (21.82±11.40)% and (71.80±21.35)% of maximum bite force of the whole primary dentition. All of the occlusal balance points located in posterior teeth regions. Occlusal contacts were observed at both anterior and posterior teeth of primary dentition with individual normal occlusion. Conclusions: There was a great variation of maximum bite forces of primary dentitions at intercuspal position of children with individual normal occlusion. Maximum bite force of primary dentition was significantly correlated with occlusal contact area, height and weight of children. Occlusal contact points with maximum bite pressure and occlusal bite balance points of primary dentitions mostly located in primary molar regions.