title: Periodontal regeneration of transplanted rat molars after cryopreservation.
abstract: The effects of cryopreservation on periodontal regeneration of transplanted rat molars were investigated histologically and histochemically in rats. Bilateral first and second maxillary molars of 4-week-old Wistar rats were gently extracted and transplanted into the abdominal subcutaneous connective tissue immediately or after cryopreservation in liquid nitrogen overnight. Donor teeth were slowly frozen by a rate-controlling freezer (program freezer) using 5% dimethylsulfoxide (DMSO) and 6% hydroxyethyl starch (HES) as cryoprotectants. One-four weeks after transplantation, they were carefully excised with the surrounding tissues. Regeneration of acellular cementum, periodontal ligament, and alveolar bone were observed 2 weeks after immediate transplantation. The pulp was repaired by the ingrowth of granulation tissue from the root apex followed by the formation of calcified tissue. The regenerated periodontal ligament was positive for alkaline phosphatase (ALP). Small or mononuclear tartrate resistant acid phosphatase (TRAP) positive cells were scattered on the newly formed alveolar bone and on the hard tissue in the pulp, but there was no external or internal progressive root resorption at 4 weeks. Cryopreserved teeth had acellular cementum with a rough surface at 1 week, but with the increase of cementoblasts and the appearance of periodontal ligament and alveolar bone, the surface became smooth at 3 weeks. Epithelial rests of Malassez (ERM) also revived. After regeneration of the periodontal tissues at 4 weeks, there was no evidence of root resorption. Although the process proceeded slowly, the cryopreserved teeth showed the periodontal regeneration substantially similar to that of the immediately transplanted teeth without progressive root resorption, indicating that they could be applicable for clinical use.
authors.affiliation: Department of Regeneration and Reconstruction, Division of Reconstructive Surgery, Course for Oral Life Science, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Naoko
authors.initials: N
authors.lastname: Kawasaki
authors.forename: Yoshioki
authors.initials: Y
authors.lastname: Hamamoto
authors.forename: Tamio
authors.initials: T
authors.lastname: Nakajima
authors.forename: Kazuharu
authors.initials: K
authors.lastname: Irie
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Ozawa
mesh_terms: D000469:Alkaline Phosphatase / Q000032:analysis; D000539:Alveolar Process / Q000502:physiology; D000818:Animals; D015925:Cryopreservation; D003739:Dental Cementum / Q000502:physiology; D008297:Male; D008963:Molar; D010513:Periodontal Ligament / Q000201:enzymology; D010519:Periodontium / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012038:Regeneration; D013997:Time Factors; D014090:Tooth Replantation; D014182:Transplantation, Autologous
chemical_list: D000469:Alkaline Phosphatase