Liesbeth Temmerman

Influence of cryopreservation on human periodontal ligament cells in vitro

Cryopreservation of teeth before autotransplantation may create new possibilities in dentistry. The purpose of this study was to examine the effect of a standardised cryopreservation procedure on human periodontal ligament (PDL) cell cultures. Human PDL fibroblasts obtained from immature third molars of 11 patients were cultured and divided into two groups. The experimental group was cryopreserved and cultured after thawing. The control group was cultured without cryopreservation. A comparison was made between cryopreserved and control cells. To evaluate possible differences in the characteristics of the fibroblasts, the cells in both groups were tested for viability (membrane integrity), growth capacity and alkaline phosphatase (ALP) expression. The Wilcoxon test for paired comparison between cryopreserved and non-cryopreserved cells was performed for each characteristic. The results showed that membrane integrity of cells was not influenced by cryopreservation. There was no statistically significant difference in growth capacity between cryopreserved and control cells. Non-cryopreserved cells were slightly stronger positive for ALP, but the difference was not statistically significant. From these experiments it can be concluded that the observed parameters are not influenced by cryopreservation.

Pulpal regeneration and root development after subcutaneous transplantation of cryopreserved immature teeth in rats.

The purpose of this in vivo study was to investigate revascularization and root growth after autotransplantation of cryopreserved immature teeth. Immature molar teeth were extracted in 4-week-old Wistar rats. In the test group, teeth were cryopreserved for 1 week and transplanted subcutaneously to the abdomen. In the control group, teeth were transplanted subcutaneously immediately after extraction. Material was collected in test and control animals at intervals of 1, 2, 4 and 10 weeks post-transplantation and histological and microradiographical examination was performed. Results showed that during the first weeks after transplantation, pulpal repair was similar in both groups although degenerated pulpal tissue was replaced slower in cryopreserved teeth and some differences in types of hard tissue formation were found between test and control teeth. After 10 weeks, the differences in the regenerated pulpal tissue between cryopreserved and control teeth observed during the first weeks were no longer detectable. No root growth was detected microradiographically 10 weeks after transplantation in any of the transplanted teeth. The presence of dentin-like tissue in the pulp cavity of some autotransplanted cryopreserved teeth, suggests survival of pulpal tissue after cryopreservation.

An experimental study on periodontal regeneration after subcutaneous transplantation of rat molar with and without cryopreservation: an in vivo study.

This study analysed the effects of cryopreservation on periodontal regeneration of autotransplanted rat molars. First and second maxillary molars (n=92) of 24 four-week-old Wistar rats were gently extracted and autotransplanted into the abdominal tissue immediately (control group n=44) or after cryopreservation in liquid nitrogen for 7 days (experimental group n=48). At 1, 2, 4 and 10 weeks after transplantation, the transplanted molars were excised and regeneration of the periodontal tissues was analysed on histological sections stained with routine H&E and Goldner method. Different tissue responses were scored on a tooth basis: inflammation, regeneration of the periodontal ligament, resorption/apposition of cementum, and alveolar bone formation. Sixty-two teeth were available for histological evaluation, including 30 experimental and 32 control samples. One week after transplantation, both control and test teeth were surrounded by granulation tissue and some areas of root resorption could be seen. After 2 weeks, signs of regeneration of the periodontal ligament, cementum apposition, and new bone formation roughly coincided in both groups, however markedly retarded in the experimental group. After 4 weeks, regeneration progressed equally in both groups, presenting fewer areas of cementum apposition in experimental samples. Finally, 10 weeks after baseline transplantation, no significant differences between both groups could be observed. Cryopreservation followed by autotransplantation of extracted teeth in rats appears to have minimal detrimental effects on regeneration of periodontal tissues after integration periods of 1-10 weeks. However, the present findings indicated that the regeneration process in general is retarded for cryopreserved teeth, as compared to their immediately transplanted homologues.

A retrospective intercenter comparison of two surgical protocols through the dental arch relationship of 5- to 6-year-old unilateral cleft patients

ObjectivesThe objectives of this retrospective equivalence trial were to assess the dental arch relationship of 5- to 6-year-old patients with unilateral cleft lip and palate (UCLP) treated in two specialized cleft centers with a different surgical protocol using the 5-Year-Olds’ Index and the modified Huddart/Bodenham scoring system, and to determine the correlation between these two scoring indices.Materials and methodsThe dental arch relationship of seventy-three 5- to 6-year-old patients with complete UCLP was evaluated on plaster casts using the 5-Year-Olds’ Index and the modified Huddart/Bodenham scoring system. The sagittal occlusion, overbite, and overjet were also recorded. Inter- and intra-examiner agreement was determined using Intraclass Correlation Coefficients.ResultsA good to very good inter- and intra-examiner agreement was found. No significant mean difference in outcome based on the 5-Year-Olds’ Index, the modified Huddart/Bodenham scoring system, overjet, or overbite was detected. For mean difference in sagittal occlusion, the hypothesis that both centers are clinically equivalent was confirmed. A strong negative correlation (rs = − 0.832) between the 5-Year-Olds’ Index and the modified Huddart/Bodenham scoring system was found.ConclusionsThe dental arch relationship of 5- to 6-year-old unilateral cleft patients treated in two Belgian cleft centers is clinically equivalent based on sagittal occlusion, despite substantial differences in their treatment protocol. Clinical equivalence for other parameters was not confirmed. There is a strong correlation between the 5-Year-Olds’ Index and the modified Huddart/Bodenham scoring system.Clinical relevanceA well-implemented treatment protocol for cleft patients is of the utmost importance, but case load and skill of the surgeon are also important factors for the quality of the results.