The risks of ankylosis of 89 avulsed human teeth stored in saliva prior to replantation-A re-evaluation of a long-term clinical study.

BACKGROUND/AIM: The survival of an avulsed tooth highly depends on the emergency management. The aim of this study was to evaluate the risk of ankylosis for avulsed human teeth stored in saliva preceded by various dry storage conditions prior to replantation. MATERIAL AND METHODS: Data include 74 patients (54 male and 20 female) with 89 avulsed and replanted teeth (16 immature teeth, 73 mature teeth). Patient ages ranged from 6 to 36 years (median: 13.0 years). All teeth were stored in saliva before replantation. Treatment and follow-up were performed according to a standardized procedure. Follow-up periods ranged from 7 months to 20 years (mean 5.3 years). The risk of ankylosis over time was estimated by the Aalen-Johansen method in relation to the length of dry storage and the stage of root development. The effect of risk factors (root development and length of dry time) on the risk of ankylosis was analysed by Cox regression analysis. RESULTS: For mature teeth, dry storage for 5 min or less before saliva storage resulted in a 47.4% (95% confidence interval (CI): 32.8-60.7) ankylosis rate. When dry storage was >5 min and <20 min, the risk of ankylosis was 76.8% (95% CI: 45.7-91.5). When dry storage exceeded 20 min prior to saliva storage, ankylosis increased to 89.3% (95% CI: 68.0-96.7). Ankylosis also increased with increasing saliva storage time. Specifically, one additional minute of wet time increased the ankylosis hazard rate (HR) by approximately 1% (CI = [0%, 2%], p = .052). Teeth with mature root development were significantly more frequently affected by ankylosis than teeth with immature root development (HR: 2.4 (95% CI: 1.0-5.5), p = .04). CONCLUSION: Temporary storage in saliva should be encouraged if an avulsed permanent tooth cannot be immediately replanted or a suitable storage medium such as milk or saline is not immediately available at the place of the accident.