The post‐traumatic colour change of primary incisors: a colourimetric and longitudinal study

Background Tooth colour change after trauma has been described subjectively as ranging from yellow/pink to grey/black. Aim To investigate the longitudinal colourimetric change of post‐traumatic discoloured primary incisor using an intraoral colourimeter. Design A total of 34 primary incisors from 15 boys and eight girls were studied. The mean post‐injury day during clinic visits ( SD ) and number of visit was 205.4 (194.8) and 3.9 (2.0). CIE L* (lightness), a* (green‐red) and b* (blue‐yellow) of the maxillary primary incisors were measured at every visit. The colour difference (Δ E* ab ) was calculated between the traumatized tooth and the control. Scatter graphs were made depicting the colour change of discoloured teeth and the Δ E* ab over time. Results Mean CIE L *, a * and b * of the unaffected control were 80.8 (2.29), 0.9 (0.77) and 13.1 (2.67), respectively. L * gradually decreased to 70.7 (on day 71), then slowly recovered. a * increased to 3.7 (day 29) and decreased slowly. b * only demonstrated a small change that was within the control range during the follow‐up. Δ E* ab increased to 9.58 (day 56) and decreased slowly. Conclusion The earlier recovery of a * was followed by the recovery of L *. During the post‐traumatic period, Δ E* ab failed to reach the clinically acceptable threshold.