Primary determinant for a clinically significant increase in the risk of maxillary incisor trauma in the mixed dentition

Which of the following overjet thresholds has been most consistently supported by systematic reviews as the primary determinant for a clinically significant increase in the risk of maxillary incisor trauma in the mixed dentition?

A. Overjet greater or equal to 1.5 mm 

B. Overjet greater or equal to 6 mm 

C. Overjet greater or equal to 3 mm

D. Overjet greater or equal to 4.5 mm

The correct answer is: C. Overjet greater or equal to 3 mm

Systematic reviews, including Nguyen et al. (1999) in the European Journal of Orthodontics, show that an overjet ≥3 mm approximately doubles the risk of maxillary incisor trauma in children, including mixed dentition, based on a meta-analysis of 11 studies (pooled OR ≈2.0). This threshold is consistently cited as the point where risk significantly increases, with ORs ranging from 1.94 to 5.19 in mixed dentition per Arraj et al. (2019) in Dental Traumatology (41 studies). Later reviews, like Pandis et al. (2022) in the British Dental Journal, reinforce >3 mm as a key early indicator for trauma risk in mixed/permanent dentitions (7–14 years).

Higher thresholds like ≥6 mm show stronger associations (OR 3.85) but only in permanent dentition, not consistently in mixed. ≥4.5 mm and ≥1.5 mm lack support in reviews for this stage. Thus, ≥3 mm is the most consistently backed primary determinant.