Preeruptive changes in maxillary canine and first premolar inclinations: a retrospective study on panoramic radiographs.

Introduction: Because of the close anatomic proximity of the maxillary permanent canine and first premolar, we investigated the relationship between their preeruptive positional changes in this retrospective study.

Methods: Sixty-three pairs of panoramic radiographs obtained 12 to 24 months apart from nonorthodontic subjects between 8 and 10 years old were collected. Canine and premolar inclinations to the midline and mesiodistal sector locations were measured, and their changes over time were estimated. The relationship between changes in canine (Δα) and premolar inclinations (Δπ) was explored alone and after adjustment for intraosseous distance between the teeth (Sc-p) and months between radiographs (ΔM).

Results: Except for right canine sector, both canine and premolar inclinations and sectors showed significant differences between time points. Pearson partial correlation analysis showed a strong, positive correlation between Δα and Δπ after adjusting for Sc-p and ΔM (right: r = 0.766, P <0.05; left: r = 0.785; P <0.05).

Conclusions: Canine and premolar inclinations and mesiodistal locations varied significantly between 8 and 10 years of age. The strong positive correlation between the preeruptive positional changes of the maxillary canine and the first premolar suggested that with a greater uprighting movement of the long axis of the premolar over time, there was greater uprighting of the long axis of the canine.