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, weinvestigated 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 between8 and 10 years old were collected. Canine and premolar inclinations to the midline and mesiodistal sectorlocations were measured, and their changes over time were estimated. The relationship between changes incanine (δα) and premolar inclinations (δπ) was explored alone and after adjustment for intraosseous distancebetween the teeth (Sc-p) and months between radiographs (δM). Conclusions: Canine and premolar inclinations and mesiodistallocations varied significantly between 8 and 10 years of age. The strong positive correlation between thepreeruptive positional changes of the maxillary canine and the first premolar suggested that with a greater uprightingmovement of the long axis of the premolar over time, there was greater uprighting of the long axis of thecanine. Results: Except for right canine sector, bothcanine and premolar inclinations and sectors showed significant differences between time points. Pearson partialcorrelation analysis showed a strong, positive correlation between δα and (δπ after adjusting for Sc-p and δ M(right: r 5 0.766, P < 0.05; left: r 5 0.785; P < 0.05).