Formation of ligamentous cementum-like tissues around dental implants

Formation of ligamentous cementum-like tissues around dental implants
10 March 2005
A. MIYASHITA, K. KOMATSU, A. SHIMADA, S. SHIMODA, S. FUKUSHIMA, and S. OIDA, Tsurumi University, Yokohama, Japan
IADR
Objective: Peri-implant tissues resembling periodontal ligament have been achieved around dental implants in monkeys and dogs. Our aims are to observe the formation of ligamentous tissues around implants installed in the sockets of a rat model, and to investigate the support function of the peri-implant tissues. Methods: Forty-three male Wistar rats, aged 6 weeks, were divided into experimental (n=26) and control (n=17) groups. Under anaesthesia, the maxillary first molar in each rat of the experimental group was extracted, and a titanium tooth-shaped implant was placed into the socket with adhering periodontal ligament. At 7, 14, 21, and 28 days, the implants in the experimental (n=12) and control (n=8) groups were scanned with micro-computed tomography and undecalcified sections were then prepared. The remaining rats (n=14) in the experimental group were sacrificed at 14 and 28 days, and those (n=9) in the control group, at 0 day. The force required to extract the implant or natural tooth from its socket was measured with a universal testing machine. Results: Thin layers of cementoblast-like cells, surrounded by an amorphous substance, lined implant surfaces at 7 days. Some extracellular matrices on the surfaces of the implants and bones were connected by collagen fibres. Collagen fibres were observed running in various directions in the gingival region within 7 days and in the apical and middle regions at 21 and 28 days. The extraction force in the experimental group increased significantly from 14 (25% of control) to 28 (68% of control) days (p<0.05). The mean value in the 28-day experimental group was less than that in the control group, although the difference was not significant. Conclusion: These findings suggest that placement of a dentalimplant into the socket with adhering periodontal ligament leads to formation of cementum-like attachments with inserted collagen fibres on the implant surface.