Influence of cyclosporin A therapy on bone healing around titanium implants: A histometric and biomechanic study in rabbits

Background: Immunosuppressive agents may induce severe changes on bone metabolism. The purpose of the present study was to evaluate the influence of the administration of cyclosporin A (CsA) on the bone tissue around titanium implants. Methods: Eighteen New Zealand rabbits were randomly divided into 2 groups of 9 each. The test group (CsA) received daily subcutaneous injection of CsA (10 mg/kg body weight) and the control group (CTL) received saline solution by the same administration route. Three days after therapy began, 2 implants (7.0 mm long and 3.75 mm in diameter) were inserted bilaterally at the region of the tibial methaphysis. After 4, 8, and 12 weeks the animals were sacrificed and biomechanical tests and histometrical procedures, consisting of the determination of the percentages of bone-implant contact and bone area within the limits of the implant threads, were performed. Results: Intergroup analysis showed that the removal torque and the percentage of bone contact with the implant surface for CsA group were significantly lower than those of the CTL group at 12 weeks (28.5 and 39.2 N cm, P = 0.01; 7.76% and 18.52%, P = 0.02, respectively). Conclusion: The data from the present study suggest that long-term administration of cyclosporin A may negatively influence bone healing around dental implants.74797698

Histometric Analysis of Bone Repair in Bone-Implant Interface Using a Polylactic/Polyglycolic Acid Copolymer Associated With Implants in Rabbit Tibia

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The purpose of this study was to evaluate the association of the combination of polylactic/polyglycolic acid around implants installed with and without primary stability through the histometric analysis of bone-implant interface. We used male rabbits, each of which received 2 titanium implants in each tibial metaphysis. The animals were divided into 4 groups: control with primary stability (CPS), control without primary stability (C), polymer with primary stability (PPS), and polymer without primary stability (P). Euthanasia was performed at postoperative days 40 and 90. The pieces were embedded in resin, sectioned, scraped, and stained with alizarin red and Stevenel blue. Histometric analysis evaluated the linear extension of contact between the bone and implant surface on the implant collar (CIC) and contact between the bone and implant surface on the first thread (CFT). Also evaluated was the area of newly formed bone (ANB) in the first thread. The results showed that there was new bone formation in all groups and during all periods. At 40 days, the ANB was higher in the PPS group than in the P group (P < .001); the CFT was statistically higher in the CPS group than the PPS group (P < .001) and was higher in the CPS group than the C group (P < .001). At 40 and 90 days, the CIC was higher in the P group than in the C group (P < .001). In conclusion, the copolymer had biocompatibility, enhanced bone healing, and presented osteoconductive properties, thus raising the contact between bone and implant, even without primary stability.381SI449457Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

Cyclosporine-a And Bone Density Around Titanium Implants: A Histometric Study In Rabbits

Aim: Cyclosporine A (CsA) is an immunosuppressive agent commonly used to prevent organ transplantation rejection. It has been demonstrated that CsA may negatively affect osseointegration around dental implants. Therefore, the aim of this study was to evaluate the effect of CsA administration on bone density around titanium dental implants. Materials and Methods: Fourteen New Zealand rabbits were randomly divided into 2 groups with seven animals each. The test group (CsA) received daily subcutaneous injection of CsA (10mg/kg body weight) and the control group (CTL) received saline solution by the same route of administration. Three days after the beginning of immunosuppressive therapy, one machined dental implant (7.00 mm in lenght and 3.75 mm in diameter) was inserted bilaterally at the region of the tibial methaphysis. After 4 and 8 weeks the animals were sacrificed and the histometrical procedures were performed to analyse the bone density around the first four threads of the coronal part of the implant. Results: A significant increase in the bone density was observed from the 4- to the 8 week-period in the control group (37.41% + 14.85 versus 58.23% + 16.38 - p <0.01). In contrast, bone density consistently decreased in the test group overtime (46.31% + 17.38 versus 16.28 + 5.08 - p <0.05). In the 8-week period, there was a significant difference in bone density between the control and the test groups (58.23 + 16.38 eand16.28 + 5.08 - p= 0.001). Conclusion: Within the limits of this study, long-term CsA administration may reduce bone density around titanium dental implants during the osseointegration process.322529Albrektsson, T., Bone tissue response (1985) Tissue Integrated Prosthesis Osseointegration in Clinical Dentistry, pp. 129-144. , Brånemark P-I, Zarb G, Albrektsson T, eds, Chicago: QuintessenceMargonar, R., Sakakura, C.E., Holzhausen, M., Pepato, M.T., Alba Jr., R.C., Marcantonio Jr., E., The influence of diabetes mellitus and insulin therapy on biomechanical retentionaround dental implants: A study in rabbits Implant Dent, , in pressTakeshita, F., Murai, K., Iyama, S., Ayukawa, Y., Suetsugu, T., Uncontrolled diabetes hinders bone formation around titanium implants in rat tibiae. A light and fluorescence microscopy, and image processing study (1998) Journal of Periodontology, 69 (3), pp. 314-320Dao, T.T., Anderson, J.D., Zarb, G.A., Is osteoporosis a risk factor for osseointegration of dental implants? (1993) Int J Oral Maxillofac Implants, 8, pp. 137-144Mendes Duarte, P., Cesar-Neto, J.B., Sallum, A.W., Sallum, E.A., Nociti Jr., F.H., Effect of estrogen and calcitonin therapies on bone density in a lateral area adjacent to implants placed in the tibiae of ovariectomized rats (2003) Journal of Periodontology, 74 (11), pp. 1618-1624. , DOI 10.1902/jop.2003.74.11.1618Granström, G., Radiotherapy, osseointegration and hyperbaric oxygen therapy (2000) Periodontol, 33, pp. 145-162Cesar-Neto, J.B., Duarte, P.M., Sallum, E.A., Barbieri, D., Moreno Jr., H., Nociti Jr., F.H., A comparative study on the effect of nicotine administration and cigarette smoke inhalation on bone healing around titanium implants (2003) Journal of Periodontology, 74 (10), pp. 1454-1459. , DOI 10.1902/jop.2003.74.10.1454Duarte, P.M., Filho, G.R.N., Sallum, E.A., De Toledo, S., Sallum, A.W., Nociti Jr., F.H., The effect of an immunosuppressive therapy and its withdrawal on bone healing around titanium implants. 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