technetium-tc-99m-medronate and Jaw--Edentulous

The aim of this study was to evaluate the osteoblastic activity around delay-loaded intraosseous dental implants using nuclear medicine imaging techniques.. Seven totally edentulous patients (two females and five males, between 48 and 57 years of age) were included in the study. Two implants were inserted into mandibular canine regions and removable prostheses were produced after 3 months. Whole-body bone scintigraphies with 20 mCi technetium 99m labelled methylene diphosphonate were taken from the patients before implant insertion, 3 months after implant placement just before the prostheses were made and 1 year after implant placement. Standardized count/pixel (SC/P) rates were calculated for each patient. Preimplantation SC/P values were compared with the 3- and 12-month values. Three-month values were compared with the 12-month values as well.. SC/P rates in the third month were significantly higher (P<0.05) than preoperative values and the SC/P rates of the 12th month were significantly lower (P<0.05) than 3-month values. The SC/P rates of the 12th month were relatively higher than first scintigraphies but the difference was insignificant (P>0.05).. Within the limitations of this study, in which delayed loading was applied, we showed that osteoblastic activity persisted more in delay loaded implants than immediate and early loading. After 1 year, there was no cellular activity around two implants and this implied that two implants were sufficient for a total prosthesis.

Topics: Analysis of Variance; Dental Implantation, Endosseous; Dental Implants; Dental Prosthesis, Implant-Supported; Female; Humans; Jaw, Edentulous; Male; Middle Aged; Osseointegration; Osteoblasts; Radionuclide Imaging; Radiopharmaceuticals; Statistics, Nonparametric; Technetium Tc 99m Medronate; Treatment Outcome

To evaluate the integration process of endosseous dental implants by using quantitative bone single photon emission computerized tomography (SPECT).. Five consecutive patients receiving titanium implants (Astra Tech, Mölndal, Sweden) in the normal edentulous jaw were evaluated by bone SPECT before loading and at regular intervals up to 5 months after loading. Osteoblastic activity at the implant site was compared with activity within the skull (reference) to calculate an osteoblastic activity index (AI).. A time activity curve obtained by plotting AI against time over 5 months showed 3 distinct phases of osteoblastic activity: (1) a rise in osteoblastic activity, part of which may reflect postoperative changes, (2) maximum activity about 1 month after implant, and (3) a gradual falloff in the AI, which returned to pre-implant levels at about 4 months.. We conclude that this method offers a simple, reproducible, objective, and physiologic approach to studying the osseous integration process that occurs after endosseous dental implants. In this small series of patients, this osseous integrative process appears to have become established approximately 4 months after loading. This method also has the capability of quantitating bone activity in absolute terms of microCi/gram (microcuries per gram) and can be useful when bone grafting and other surgical procedures are involved.

Topics: Dental Implantation, Endosseous; Dental Implants; Female; Humans; Jaw, Edentulous; Male; Middle Aged; Osseointegration; Osteoblasts; Radiography; Technetium Tc 99m Medronate; Tomography, Emission-Computed, Single-Photon

The aim of the present study was to evaluate the healing of onlay grafts to edentulous jaws in conjunction with osseointegrated implants using single photon emission computed tomography (SPECT). In all, 24 patients were examined who had received 26 full arch onlay grafts for augmentation of extremely atrophic edentulous jaws with secondary placement of implants 21.4 weeks after grafting. 99m-technetium-MDP scintigrams were performed immediately after grafting, before implant placement, after implant placement and before abutment connection. Tracer accumulation was assessed semiquantitatively by calculating ratios of count densities between the uptake over the calvarium and over the grafted jaws based on 16 regions of interest in the reconstructed tomograms corresponding to 16 possible areas of implant placement. There was a significant decrease in tracer uptake during graft healing, which was followed by a significant increase after implant placement and a subsequent decrease during implant healing. In 3 patients, infection and partial necrosis of the grafted bone occurred. In these cases, tracer uptake in areas of subsequent graft infection immediately after grafting was significantly lower compared to patients with uneventful healing as a sign of inferior graft revascularization. In 3 patients, 14 implants failed due to mobility at the time of abutment connection or loss of osseointegration within the first weeks thereafter. Significantly lower levels of tracer uptake immediately after grafting and during graft healing were found in these areas, representing a lack of bone turnover due to decreased revascularization. These areas also showed a lower increase in tracer accumulation after implant placement due to the inferior graft quality, followed by a significant increase of peri-implant bone turnover at the time of abutment connection representing inflammatory peri-implant bone reaction.

Topics: Adult; Aged; Bone Transplantation; Dental Abutments; Dental Implantation, Endosseous; Female; Humans; Jaw, Edentulous; Male; Mandible; Maxilla; Middle Aged; Prospective Studies; Technetium Tc 99m Medronate; Time Factors; Tomography, Emission-Computed, Single-Photon; Wound Healing