Evaluation of clinical and radiographic scoring methods before and after initial periodontal therapy

The purpose of the present study was to compare the determination of the attachment level by probing and by measuring bone heights prior to and after completion of a hygienic phase of periodontal therapy. 68 patients with moderate to severly advanced periodontitis underwent initial (hygienic phase) therapy including scaling and root planing, oral hygiene instructions and the elimination of plaque retention factors. Measurements of pocket probing depths, probing attachemnt levels and the location of gingival margins in relation to the cemento-enamel junction were performed at 4 aspects of each tooth with a thin calibrated probe at a baseline examination and 3 to 5 months following treatment. During these 3 to 5 months, the patients were kept in a maintenance care program. On the full-mouth radiographs obtained at baseline, the distance from the cemento-enamel junction to the marginal alveolar crest was measured in millimeters and as a % of the root length. Furthermore, a subgroup of 11 patients, who were scheduled for modified Widman flap procedures, received another full-mouth radiographic examination before the surgical treatment. In addition, the level of the alveolar crest was assessed with a periodontal probe during the surgical procedure. The comparison of the different clinical and radiographic parameters showed the best correlations between the various radiographic measurements of bone heights (r=0.87; r=0.86). Clinical measurements of probing attachment level and probing level of the alveolar crest revealed slightly weaker correlations (r=0.72). When comparing radiographic bone heights with clinical measurements of probing attachment levels, the lowest correlations were found (r=0.65; r=0.61; r=0.61).link_to_subscribed_fulltex

Temporal dynamics of healing in rabbit cranial defects using guided bone regeneration

Purpose: The objective of this study was to histologically evaluate the early stages of bone regeneration using rabbit calvaria defects in conjunction with guided tissue regeneration. Materials: A semilunar cutaneous-periosteal flap was raised on the forehead of four rabbits exposing the top of the skull. A standardized transosseous skull defect (≥ 15 mm in diameter) was made in the area of the right parietal bone with a rotating round bur. Care was taken not to damage the underlying dura. A flat expanded polytetrafluoroethylene (ePTFE) membrane was placed to cover the defect. The membrane was tightly adapted, extending at least 4 mm onto intact bone, and the flap was sutured. One, 2, 3, and 5 weeks later, the specimens were removed and processed using standard, undecalcified, hard-tissue histologic techniques. Contact radiographs were also taken. Results: Bone growth increased with time, starting at the borders of the defect. At 1 week, trabeculae of woven bone grew into the highly vascularized loose connective tissue occupying the defect. Two weeks postsurgery, isolated islands of new bone were detected in this connective tissue. Subsequently, neighboring small islands merged to form large islands. In later stages, the primary trabeculae of woven bone were reinforced by layers of regularly deposited lamellar bone. Conclusion: Rabbit calvaria defects treated by guided tissue regeneration heal by ingrowth of woven bone from the defect margins and by formation of bony islands within the defect area. Bone healing showed the histophysiological characteristics of intramembranous bone.link_to_subscribed_fulltex

Evaluation of an in situ formed synthetic hydrogel as a biodegradable membrane for guided bone regeneration

The aim of the present study was to test whether or not the application of an in situ formed synthetic hydrogel made of polyethylene glycol (PEG) used as a biodegradable membrane for guided bone regeneration will result in the same amount of bone regeneration as with the use of an expanded polytetrafluoro- ethylene (ePTFE) membrane. In eight New Zealand White rabbits, four evenly distributed 6 mm diameter defects were drilled into the calvarial bone. Three treatment modalities were evenly distributed among the 32 defects: hydroxyapatite (HA)/tricalciumphosphate (TCP) granules covered at the outer and inner surface with a PEG membrane (test), HA/TCP granules covered at the outer and inner surface with an ePTFE membrane (positive control) and HA/ TCP granules alone without membranes (negative control). After 4 weeks, the animals were sacrificed and the calvarial bones were removed. The area fraction of newly formed bone was determined by histomorphometrical analysis of the vertical sections from the middle of the defect and by micro-computed tomography of the entire defect. Multiple regression analysis (SAS® GLM) was used to model the amount of new bone formation. The quantitative histomorphometric analysis clearly revealed higher values of newly formed bone for the two membrane groups compared with the negative control group. The average area fractions of newly formed bone measured within the former defect amounted to 20.3 ± 9.5% for the PEG membrane, 18.9 ± 9.9% for the ePTFE membrane, and 7.3 ± 5.3% for the sites with no membrane. The micro-computed tomography also showed higher values of new bone formation for the PEG and for the ePTFE groups compared with the negative control group. The GLM revealed a highly significant effect of the treatment on the amount of bone formation (P = 0.0048). The values for the negative control group were significantly lower than the ones found in the PEG membrane group (P = 0.0017), whereas the ePTFE membrane group showed no significant difference from the PEG membrane group. It is concluded that the PEG membrane can be used successfully as a biodegradable barrier membrane in the treatment of non-critical-size defects in the rabbit skull, and leads to similar amounts of bone regeneration as an ePTFE membrane. Copyright © Blackwell Munksgaard 2006.link_to_subscribed_fulltex