Abstract
OBJECTIVES: The incidence and clinical characteristics of bi-rooted primary canines were investigated by performing oral panoramic radiographs. METHODS: A total of 100 976 oral panoramic radiograph of subjects aged 3-9 years old were collected, and the incidence and distribution of bi-rooted primary canines were observed and recorded. The obtained data were analyzed using SPSS 25.0 statistical software, and the literature on bi-rooted primary canine was reviewed to record patient's data. RESULTS: The incidence of bi-rooted primary canines was 0.37‰ (37/100 976), of which 0.59‰ (32/54 276) occurred in males and 0.12‰ (5/46 700) in females. Statistically significant difference was observed between males and females (χ(2)=15.955, P=0.000). The number of bi-rooted primary canine in 37 children was mainly 1-2. Among them, 11 subjects (29.73%) had one bi-rooted primary canine, and 18 subjects (48.65%) had two bi-rooted primary canines. The tooth position distribution of 76 bi-rooted primary canines showed no significant difference between the left and right sides (χ(2)=1.316, P=0.251). However, significant difference was found between the upper and lower jaws (χ(2)=15.213, P=0.000) and between the unilateral and bilateral sides (χ(2)=6.083, P=0.014). CONCLUSIONS: Bi-rooted primary canines are rare, mostly occur in 1-2 teeth, and are more common in males than females, in the upper jaw than in the lower jaw, and on both sides than on one side.