Implant osseointegration in the irradiated mandible

Abstract

This research focuses on the effects of radiotherapy on the osseointegration of dental implants placed before or after radiotherapy in 11 male beagles. After the extraction of all mandibular premolars 1st and 2nd molars, three dogs were implanted without radiotherapy (Control group), four dogs were irradiated 4 weeks after implantation (IrA group) and four dogs were irradiated 8 weeks before implantation (IrB group). Eight implants were placed in each dog, in an alternating pattern: four nonsubmerged ITI Bonefit titanium plasma spray-coated and four submerged Steri-Oss hydroxyapatite-coated. The irradiated dogs received 4.3 Gy daily for 10 days. Two different fluorescent markers were administered at the time of implantation and of irradiation. The dogs were sacrificed 6 months after implantation, i.e. 5 months after radiotherapy for the IrA group and 8 months for the IrB group. Each mandible was submitted to histological and microradiographic analysis. Bone formation occurred around 85 of the 88 implants and consisted mostly of the successive deposit of woven and lamellar bone. Both irradiated groups showed obvious bone remodeling in alveolar bone as well as in the basilar part of the mandible. Nevertheless, in the IrA group, the resorption phenomena predominated over osteogenesis. The balance between these two opposite processes seemed to be restored 8 months after the end of radiotherapy (IrB group). In spite of focal lesions of radiation-specific bone destruction emphasized in some irradiated dogs, we conclude from our results that osseointegration of dental implants is possible in irradiated bone tissue.

Effects of irradiation on bone remodelling around mandibular implants: an experimental study in dogs

“…Cortical bone remodelling was in progress several weeks after irradiation and appeared to follow its normal course, contrary to the findings in rabbits 18,24 . These observations therefore strengthen previous recommendations about radiotherapy planning 4,8,12 . In particular, the therapeutic timing and length of delay between irradiation and implantation appear decisive to ensure the correct osteogenic reaction and thus osseointegration.…”

“…As described previously 7,8 , the clinical stability observed in all control implants, as well as in 61 of the 64 irradiated implants, clearly results from direct bone-implant contact, visible on the microradiographs of undecalcified sections (Fig. 3).…”

“…Experimental data on the rabbit suggested long-term impairment of bone remodelling after post-implantation irradiation 18,24 . In contrast, histological analysis of mandibular bone of dogs 24 weeks after implantation showed a higher level of remodelling in the irradiated animals than in the non-irradiated ones 8 . This qualitative observation was mostly restricted to the bone-implant interface.…”

Dental Implants Installed in Irradiated Jaws

“…It has been suggested that a six-month period between irradiation and implantation should be implemented to allow improved bone apposition and adequate osseointegration (Brasseur et al, 2006). This finding is in line with data from Brogniez et al (2002), who reported progressive deposition of woven and lamellar bone around implants placed before or after irradiation of the bone, as well as a positive balance between bone resorption and remodeling after 8 weeks of radiotherapy. Histologic data on removed implants from irradiated human jaws suggest that bone anchorage of these implants is feasible (Bolind et al, 2006).…”

Measurement of Elastic Modulus and Vickers Hardness of Surround Bone Implant Using Dynamic Microindentation - Parameters Definition

“…Trabecular bone has a porous structure and is located in medullary cavities (9,10). The effect of the implant parameters, bone quality and characteristic modulated by different aspects like aging, irradiation, tobaccoism, coffee consumption and alcohol consume, have been evaluated using several laboratory techniques (4,(10)(11)(12). From a macro-biomechanical perspective, the anchorage of implants has been assessed using tensile tests (13), torque (14), pull-out (2) and push-in tests (2).…”