Autotransplantation of maxillary second premolars to mandibular recipient sites where the primary second molars were impacted, predisposes for complications.

Objective: The aim of the study was to elucidate whether ankylosis of a transplanted permanent tooth can be predicted based on an evaluation of the primary and permanent dentitions.

Materials And Methods: The study comprised 162 maxillary second premolars and 49 third molars transplanted to the mandibular second premolar region in 157 patients treated in the period 1980-2003.

Selection Criteria: panoramic radiograph available; agenesis of the mandibular permanent premolar/s; persistence of the primary molar at the recipient site. The 211 transplanted teeth were observed for a period of between 1-29 years.

Results: Seven per cent (95% confidence interval, CI = 3-11%) of the transplanted second premolars ankylosed during the first 10 years after operation. The success rate for transplantation of the third molar to the mandibular second premolar region was significantly lower (p = 0.001), as 40% (95% CI = 24-57%) of the third molars had ankylosed 10 years after operation. A significant association (p = 0.022) was found between ankylosis of a second premolar and infra-position of the primary second molar located at the recipient site. The infraposition group had 13% (CI = 4-23%) ankylosis after 10 year, whereas the non-infraposition group had 5% (CI = 1-9%) ankylosis after 10 years.

Conclusions: The present study concludes that there is an increased risk of ankylosis of the transplanted permanent tooth if the primary tooth at the recipient site is in infraposition. This observation may be decisive for treatment planning, especially in young individuals in whom excessive growth of the alveolar process is expected from the cephalometric analysis.