Age, gender and degree of inclusion are predictors of timing for spontaneous repositioning of intruded primary teeth in pre-school children

Aim To investigate the timing for spontaneous repositioning of primary teeth with intrusive luxation in relation to degree of inclusion, gender and age of injured children. Methods This retrospective study analysed records of 1 to 6-year-old children referred to the Section of Paediatric Dentistry, C.I.R. Dental School, University of Turin (Italy) between January 2009 and December 2020 for traumatic intrusion of primary teeth. Time to the total re-eruption was calculated, and related factors were explored using Cox and Kaplan-Meier analyses. Results Data from 151 intruded teeth in 104 children (56 boys and 48 girls, median age 2.3 years) were reviewed. One hundred twenty (77.9%) teeth were totally and 31 (22.1%) were partially intruded. Trauma involved most the maxillary central incisors and it was more common at home. All teeth re-erupted spontaneously in a few months. Time to total re-eruption varied from 2 weeks to 11 months with a mean time of 4.3 months. All partially intruded teeth completely re-erupted within the first 5 months, with no significant impact of gender and age. In contrast, male gender and age at trauma were statistically associated to the time of re-eruption of totally included teeth (p <0.001). In children younger than 2 years eruption occurred within a maximum of 5 months after trauma, while in those older than 2 years it usually required 5 to 11 months. Conclusion Timing for spontaneous re-eruption seems to be associated to age, particularly as far as total intrusion of primary teeth is concerned. This observation could be related to the degree of bone mineralisation, which is modified during growth.