Evaluation of the effects of diagnostic radiation on titanium dental implant osseointegration in the micropig
The aim of this study was to compare any difference in titanium implants exposed and not exposed to radiation of varying doses. The researchers took nine micropigs and surgically extracted mandibular premolars. After 10 weeks of healing, titanium implants were inserted in a split-mouth design with three implants in either side of the mouth. The animals were randomly assigned to one of three groups: control, radiation x 2 doses, or radiation x 10 doses at implant placement. The experimental animals had a specially designed Inn XCP device that was secured to the implants. Sham radiation exposure was performed on the contralateral side of each experimental animal. Sites adjacent to and cross arch from each radiated implant were shielded. Three control animals were subjected to sham x-rays on one side of the mandible (with stent affixed), while the contralateral side received no radiation .All radiographs were taken using a Phillips Oralix 50, 50kVp, 7.5mA, portable dental x-ray machine. An exposure time of 2.5 seconds was employed. After a 14-week healing period, radiographs of all implants were obtained and overlaid on a transparent grid marked in millimeters and viewed without magnification. Their results showed that the success rate for all implants was 83%.
In the control group, two implants perforated the mucosa and had marked inflammation and calculus. For the group receiving two doses of radiation, three control implants perforated with the tissue exhibiting edema and implant exhibiting calculus. The group receiving 10 doses had three implants (two control and one experimental) perforate the soft tissue and showed calculus over the implant. SEM studies showed 59 control specimens yielded a range of 15% to 81% implant length in contact with bone (contact length fraction, CLF).The mean CLF for all controls was 47.72%. The mean CLF for implants receiving two doses of diagnostic radiation was 53.83% with a range of 20% to 70%. Implants that had excessive doses of radiation showed a CLF of 53.15 with a range of 14% to 84%. Both control and radiated implants showed a wide range of bone-to-implant appearances as well as crestal bone resorptions. Statistical analysis showed there was no statistically significant difference between groups when paired by implant site, radiation or none, or stent applied or not. Radiographic exam revealed that all implants exhibited crestal alveolar resorption from 0 to 3.5 mm. Histologic evaluation showed no difference between experimental and control implants with respect to vasculature, perivascular infiltrate, connective tissue stromal architecture, or appearance of calcified tissue. This study suggests that diagnostic dental radiographs can be used during the implant healing phase without any adverse effects. [M.C.R.]
Basquill, P.J., D. Steflik, W. Brennen, J. Homer, and T. Van Dyke, J Periodont, 65:872,1994