Enhancement of human periodontal ligament by preapplication of orthodontic loading

Long-term survival of 57 premolars consecutively transplanted to premolar sites

INTRODUCTION

The objective of this study was to report the long-term outcome of autotransplantation of premolars to other premolar recipient sites.

METHODS

The sample was limited to adolescents seeking orthodontic treatment, and all had 1 or 2 premolars transplanted to a recipient site in which a premolar was congenitally missing. The transplantations were performed between 1980 and 2008, comprising 29 premolars in 22 males and 28 premolars in 22 females. Systematic clinical and radiographic follow-up varied from 1 year to 36.8 years, with a mean observation time of 18.9 years and a median of 19.2 years. Of the 57 transplanted teeth, 52 were subjected to orthodontic forces.

RESULTS

A total of 9 of 57 teeth (15.8%) were lost during the observation period, and 8 of 9 lost teeth had been functional for at least 9 years posttransplantation. Of the 48 surviving transplants, 6 did not meet the criteria for success, giving an overall success rate of 73.7%. Complications were diagnosed within 5 years from the transplantation in 4 of 57 teeth (7.0%) and later in 11 of 57 (19.3%). The Kaplan-Meier survival curve shows that the complication-free proportion of transplants decreased at a constant rate over the observation time. The average survival time, taking censoring into account during follow-up of 36.8 years, was estimated as 28.5 years. The complications in the 15 teeth were classified into 4 categories: periapical lesions (6 teeth), inflammatory resorption (5 teeth), abrupt fracture (2 teeth), and ankylosis (2 teeth).

CONCLUSIONS

Overall, premolar transplants in all stages of root formation have high success and survival rates. Transplants with complications may survive temporarily and preserve critical arch space and alveolar bone. Transplants with normal healing may have latent weaknesses that can eventually affect long-term survival.

An evaluation of 910 premolars transplanted in the anterior region-A retrospective analysis of survival, success, and complications

AIM

The aim this retrospective analysis was to evaluate the survival, success and possible complications of transplanted premolars to the anterior region subdivided in development stage and patient's age.

MATERIALS AND METHODS

The material comprised patients that underwent a tooth transplantation between April 2004 and December 2021. A total of 910 premolars were transplanted in 707 patients. Tooth mobility, oral hygiene, and periodontal parameters were clinically evaluated. Standardized radiographs were used to evaluate pulpal and periodontal healing and root formation. The cumulative survival rate was calculated using the Kaplan-Meier method.

RESULTS

The data were subdivided in three groups based on the stage of root development and patient's age. The average age at surgery was 16 years. The main indication for transplantation was trauma, followed by agenesis and other indications. Two premolars were lost during the whole observation period. The overall survival and success in the immature premolars group after an observation period of 10 years was 99.8%. The 10-year survival and success rate when fully developed premolars were transplanted in the anterior region in adolescents were 100% and 96.3%, respectively. In adults, the 10-year survival and success rate were 87.5%.

CONCLUSION

Transplantation of premolars with developing and fully developed roots to the anterior region in children, adolescents, and adults is a predictable treatment modality.

An evaluation of 1654 premolars transplanted in the posterior region-A retrospective analysis of survival, success and complications

AIM

The aim of this retrospective analysis was to evaluate the survival, success and possible complications of transplanted premolars in the posterior region subdivided by developmental stage and patient age.

MATERIALS AND METHODS

This study included patients who underwent tooth transplantation between April 2004 and December 2021. A total of 1654 premolars were transplanted into 1243 patients. Tooth mobility, oral hygiene and periodontal parameters were clinically evaluated. Intraoral radiographs were used to evaluate pulpal and periodontal healing, and root formation. The cumulative survival rate was calculated using the Kaplan-Meier method.

RESULTS

Data were subdivided into three groups based on the stage of root development and patient age. The mean age at surgery was 14.5 years. The main indication for transplantation was agenesis, followed by trauma and other indications, such as impacted or malformed teeth. A total of 11 premolars were lost during the study period. The overall survival and success rates in the immature premolar group after an observation period of 10 years were 99.7% and 99.4%, respectively. High survival and success rates (95.7% and 95.5%, respectively) were also observed when fully developed premolars were transplanted into the posterior region of adolescents. In adults, the success rate after 10-year follow-up is 83.3%.

CONCLUSIONS

Transplantation of premolars with developing and fully developed roots is a predictable treatment modality.

Periodontal ligament proliferation and expressions of bone biomolecules upon orthodontic preloading: Clinical implications for tooth autotransplantation

Objective

Preservation of the periodontal ligament (PDL) is vital to the success of tooth autotransplantation (TAT). Increased PDL volumes and facilitated tooth extraction have been observed upon orthodontic preloading. However, it is unclear whether any changes occur in the expressions of bone biomolecules in the increased PDL volumes. This study aimed to determine the expressions of runt-related transcription factor 2 (RUNX2), alkaline phosphatase (ALP), receptor activator of nuclear factor kappa-B ligand (RANKL), and osteoprotegerin (OPG) in PDL upon preloading.

Methods

Seventy-two premolars from 18 patients were randomly assigned to experimental groups that received a leveling force for 1, 2, or 4 weeks or to a control unloaded group. Following extraction, PDL volumes from 32 premolars of eight patients (21.0 ± 3.8 years) were evaluated using toluidine blue staining. The expressions of the biomolecules in the PDL from 40 premolars of ten patients (21.4 ± 4.0 years) were analyzed via immunoblotting.

Results

The median percentage of stained PDL was significantly higher at 2 and 4 weeks after preloading than in the unloaded condition (p < 0.05). The median RUNX2 and ALP expression levels were significantly higher at 2 and 4 weeks after preloading than in the unloaded condition (p < 0.05), whereas the median RANKL/OPG ratios were significantly higher at 1 and 4 weeks after preloading (p < 0.05).

Conclusions

Orthodontic preloading for 4 weeks enhances PDL volumes as well as the expressions of RUNX2, ALP and the RANKL/OPG ratio in the PDL, suggesting this loading period is suitable for successful TAT.