ABSTRACT
Aims: To evaluate the effi cacy of autologous platelet- rich fi brin in regeneration of bone and to assess clinical compatibility of the material in mandibular third molar extraction socket. Materials and Methods: This study was conducted in 20 patients visiting the out patient department of Oral & Maxillofacial Surgery, Subbaiah Institute of Dental Sciences. Patients requiring extraction of bilateral symmetrical mandibular third molars were taken for the study. Following extraction, platelet rich fi brin prepared from patients own blood was placed in one extraction socket. The patients were assessed for postoperatively pain, periodontal pocket depth and bone blending and trabecular formation. Radiological assessment of the extraction site was done for a period of 6 months to evaluate the change in bone density. Results: All the local signs and symptoms of infl ammation were mild to moderate and subsided in normal course of time. Pain was less in study site compared to control site. Soft tissue healing was better in study site. Evaluation for bone blending and trabecular bone formation showed earlier in study (prf)site compared to control(non prf) site in 10 patients. The evaluation of bone density by radiological assessment showed the grey level values calculated at 4months at the prf site were comparatively higher than the average baseline value of bone density at extraction site in control site. Conclusion: The study showed that autologous PRF is biocompatible and has signifi cant improved soft tissue healing,bone regeneration and increase in bone density in extraction sockets. However a more elaborate study with a larger number of clinical cases is very much essential to be more conclusive regarding its effi cacy.
ABSTRACT
Objective To study the effects of electromagnetic field (EMF) exposure on osteoporosis in ovariectomized mice. Methods Sixty 8-week-old female Kunming mice were divided into four groups at random: a sham operation group (group A), an ovariectomized group (group B), an EMF and ovariectomized group (group C) and a nilestriol and ovariectomized group (group D). Bilateral ovariectomies were performed on all mice except those in group A. The mice of group C were exposured to a 15 Hz, 1.0 mT electromagnetic field. The mice of group D were given at nilestriol 1.5 mg/kg/week. The bone mineral density (BMD) of the lumbar vertebrae was measured before the mice were sacrificed at the 12th week. Blood specimens were collected every two weeks to measure the ac-tivity of alkaline phosphatase (ALP) and the concentration of bone gamma-carboxyglutamic-acid-containing proteins (BGP), calcium and estradiol in the serum. Histological sections were taken to examine and analyze the changes in bone trabeculae in the lumbar vertebrae after 6 and 12 weeks. Results EMF at 15 Hz and 1.0 mT intensity signifi-cantly increased the activity of ALP and the concentrations of BGP and calcium in the serum. In addition, the absorp-tion of bone trabeculae in the lumbar vertebrae was significantly restrained. Conclusions EMF at 15 Hz and 1.0 mT can restrain the development of osteoporosis in ovariectomized mice.
ABSTRACT
Objective: To determine the failure mode of depressive osteochondral fracture under the maximum compressive load. Design: An experimental cadaveric study. A compressive load was applied through an indenter on a femoral condyle to create a depressive osteochondral fracture until the maximum load was reached. Background: Most depressive osteochondral fractures occur without a gross articular cartilage injury because a large amount of load is reabsorbed by the surrounding tissues, especially the subchondral bone under the cartilage. We asked what the mode of depressive osteochondral fracture is. It might function as a load adsorber from the articular cartilage. Methods: Three groups of depressive osteochondral fractures were studied. Croup 1 consisted of 12 pieces of middle third of normal median and lateral femoral condyles. Groups 2 and 3 consisted of 12 pieces of osteoporotic and osteosclerotic middle of both femoral condyles. Using a universal testing machine, a depressive osteochondral fracture was created by applying a uniaxial compressive load through an indenter until the load rose to the maximum level. At that point, the load applied was stopped in order to minimize the extent of subchondral trabeculae fracture. Maximum load was recorded. Pressure and stiffness were calculated. The pattern of depressive fracture was studied histologically. Results: The failure mode of depressive osteochondral fracture wan such that the bone under the articular cartilage had a subchondral plate fracture, an interlacing of bone trabeculae under the plate, and a few fractures of the bone trabeculae. The interlacing of subchondral bone trabeculae was most evident in the normal bone as compared with the osteoporotic and osteosclerotic bones. The osteosclerotic bone failed at the highest load, while the osteoporotic bone failed at the lowest. Conclusion: The subchondral plate fracture and the interlacing of subchondral bone trabeculae under the plate are the characteristics of the failure mode of depressive ostechondral fracture. This failure mode occurs before there is a discernible fracture of the subchondral bone trabeculae. The amount of load causing fracture depends on the quality of the bone. Relevance: The failure mode, especially the interlacing of subchondral bone trabeculae, night function as a load absorber from the articular cartilage. Therefore, the quality of subchondral bone is important for protection of the articular cartilage from compressive load injury.