Postoperative irradiation after implant placement: A pilot study for prosthetic reconstruction

Abstract

PURPOSEOn maxillofacial tumor patients, oral implant placement prior to postoperative radiotherapy can shorten the period of prosthetic reconstruction. There is still lack of research on effects of post-implant radiotherapy such as healing process or loading time, which is important for prosthodontic treatment planning. Therefore, this study evaluated the effects of post-implant local irradiation on the osseointegration of implants during different healing stages.MATERIALS AND METHODSCustom-made implants were placed bilaterally on maxillary posterior edentulous area 4 weeks after extraction of the maxillary first molars in Forty-eight Sprague-Dawley rats. Experimental group (exp.) received radiation after implant surgery and the other group (control) didn't. Each group was divided into three sub-groups according to the healing time (2, 4, and 8 week) from implant placement. The exp. group 1, 2 received 15-Gy radiation 1 day after implant placement (immediate irradiation). The exp. group 3 received 15-Gy radiation 4 weeks after implant placement (delayed irradiation).RESULTSThe bone mineral density (BMD) was significantly lower in the immediate irradiation groups. BMD was similar in the delayed irradiation group and the control group. The irradiated groups exhibited a lower bone-to-implant contact ratio, although the difference was not statistically significant. The irradiated groups also exhibited a significantly lower bone volume and higher empty lacuna count than the control groups. No implant failure due to local irradiation was found in this study.CONCLUSIONWithin the limits of this study, the timing of local irradiation critically influences the bone healing mechanism, which is related to loading time of prostheses.

Bone Regeneration Effect of Hyperbaric Oxygen Therapy Duration on Calvarial Defects in Irradiated Rats

“…Radiotherapy and surgical resection are performed for the treatment of head and neck tumors and bone regeneration ability of treatment sites is reduced by radiation therapy [2]. After surgical resection, bone grafting is performed to induce bone regeneration.…”

“…Irradiation reduces the ability to regenerate bone within the irradiation range [2]. Bone exposed to radiation is in a hypocellular, hypovascular, hypoxic environment that is unfavorable compared to the preirradiation condition for bone regeneration or remodeling.…”

“…In general, the higher the radiation dose, the higher the probability that radiation osteonecrosis will occur [4]. Trauma to irradiated bone may also cause radiation necrosis [2]. The most frequent causes of trauma are extraction, ulcers caused by dentures, and periapical periodontitis [5].…”

Synergistic effect of hyperbaric oxygen therapy with PTH [1–34] on calvarial bone graft in irradiated rat

“…Because histology and histomorphometry only give two‐dimensional results, qualitative evaluation is limited. Recently, it became possible to evaluate the quality of the experimental site through various parameters of micro‐CT (Bouxsein et al, ; Doh et al, ; Huh et al, ). Therefore, it was important to select the parameters that were meaningful to this study.…”

“…Patients undergoing radiation therapy experience tissue destruction and chronic non‐healing wounds because bone marrow, collagen, periosteum, and endothelial cells are damaged, leading to tissue hypoxia (Ihde, Kopp, Gundlach, & Konstantinovic, ). Similar loss and severe fibrosis of remodeling elements occur at the periosteum as well as blood vessels; consequently, the regenerative ability of irradiated tissue gradually decreases (Doh et al, ). As a result, the failure rate of bone grafts in irradiated bone has been reported to be 2–3 times greater than that in non‐irradiated bone (Vissink, Jansma, Spijkervet, Burlage, & Coppes, ).…”