Transplantation of primary canines after loss or ankylosis of upper permanent incisors. A prospective case series study on healing and survival

Primary canines were transplanted to replace lost or ankylosed permanent upper incisors. Healing, healing complications and loss and survival were evaluated in a prospective case series study. In total, 27 primary canines were transplanted. Extraorally posts made of titanium were inserted into the root canal from a retrograde direction as an immediate endodontic treatment and as an elongation of the short autologous roots. In some cases antiresorptive- regenerative therapy was used. Inclusion criteria for the evaluation were a minimal observation period of 12 months or the observation of complications. The median observation period of the analyzed 17 transplants was 26.6 months (min: 6.7 months, max: 54.6 months). Sixteen out of seventeen transplants exhibited functional healing until the end of the observation or the occurrence of an external influence (another trauma, resorption by neighbored tooth). In no case ankylosis or arrest of alveolar growth was recorded. In some transplants resorptions not related to infection or ankylosis were observed. One transplant exhibited an early infection-related complication and was removed. One transplant was resorbed by the developing permanent canine and lost. Following another trauma five transplants were lost. External influence and new trauma were significantly related to the loss of transplants (Fisher's exact test; P = 0.0006 and 0.0034). The estimated survival according to a Kaplan-Meier analysis was 40.7 months for all transplants. It was significantly shorter for teeth which were lost in relation to an external influence (survival 28.4 months vs 44.7 months; log rank test: P = 0.0093). The transplantation of primary canines maintains bone and soft tissues of the alveolar process. The healing rate is high. However, there is a high incidence of repeated trauma episodes, causing a high loss rate. The observation period is still limited.