Histomorphometric and fluorescence microscopic evaluation of interfacial bone healing around 3 different dental implants before and after radiation therapy.
OBJECTIVE
Radiation therapy influence on bone healing around 3 types of endosseous dental implants in dogs was evaluated.


METHODS
Implants with 3 different surfaces (A = machined commercially pure titanium screws, B = commercially pure titanium plasma spray-coated cylinders, C = hydroxyapatite [HA] -ceramic coated cylinders) were first implanted unilaterally into the right posterior edentulous mandibles of 7 dogs as nonirradiated controls. After 12 weeks without functional loading and after sequential fluorochrome labeling these implants were retrieved by block dissection. In this same surgery, implants were placed on the contralateral side. Three weeks postimplantation the implant-containing hemimandibles were Cobalt 60 irradiated with the biologic equivalent of 5,000 cGy. Twelve weeks postimplantation and after labeling these irradiated implants were retrieved at sacrifice. On scanning electron, light, and fluorescence microscopic images of undecalcified longitudinal ground sections of the implants with surrounding tissues, percent bone-to-implant contact (% BIC), bone formation, and remodeling were histometrically and subjectively evaluated.


RESULTS
Woven bone formation started 1 week after implantation at the implant interfaces on both the nonirradiated and the irradiated sides. Average BICs (total/cortical/spongious bone bed) of 26%/49%/36% for surface A, 46%/48%/64% for surface B, and 81%/83%/78% for surface C were observed. In the irradiated hemimandibles average BICs (total/cortical/spongious bone bed) were reduced to 11%/9%/4% for surface A, 43%/46%/43% for surface B, and 63%/85%/76% for surface C, with increased resorption of peri-implant bone and retarded bone formation after irradiation.


CONCLUSIONS
Reductions of total % BIC in all irradiated implants, though not statistically significant, were significant (P < or = .05) on implant surfaces A and B in the spongious bone bed.


CONCLUSIONS
Retarded bone formation on surfaces A and B in the spongious bone bed represented a more radiation-sensitive situation at the time of radiation onset compared to advanced bone formation and maturation at surface C.
Weinlaender
Michael
M
Bone and Biomaterials Research, Institute for Histology and Embryology, Medical University of Vienna, Austria. office@drweinlaender.at
Beumer
John
J
Kenney
E Barrie
EB
Lekovic
Vojislav
V
Holmes
Ralph
R
Moy
Peter K
PK
Plenk
Hanns
H
D000818:Animals; D016723:Bone Remodeling / Q000528:radiation effects*; D020099:Coated Materials, Biocompatible; D003037:Cobalt Radioisotopes / Q000009:adverse effects; D016371:Cranial Irradiation / Q000009:adverse effects*; D003758:Dental Implantation, Endosseous; D015921:Dental Implants; D017267:Dental Prosthesis Design; D004285:Dogs; D017886:Durapatite; D005260:Female; D008297:Male; D008855:Microscopy, Electron, Scanning; D008856:Microscopy, Fluorescence; D016348:Osseointegration / Q000528:radiation effects*; D013499:Surface Properties; D014025:Titanium; D014945:Wound Healing / Q000528:radiation effects*
D020099:Coated Materials, Biocompatible; D003037:Cobalt Radioisotopes; D015921:Dental Implants; D017886:Durapatite; D014025:Titanium