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In This case report a surgical technique for vertical ridge augmentation is presented. The procedure, performed in a 30-year-on woman with an atrophied alveolar ridge in the anterior portion of the mandible, is based on the biologic concept of osteogenesis distraction previously introduced in orthopedic and maxillofacial surgery. After elevation of a full-thickness flap a horizontal osteotomy was performed 7 to 8 mm from the top of the ridge. Two vertical osteotomies were prepared with drills of increasing diameter (2, 2.8, and 3.25 mm), tapping was performed for the first 5 to 6 mm, and two distractor base plugs were placed at the base of the osteotomies with a repositioning tool. An intraosseous distraction implant was then inserted and 2 inward vertical cuts were mode in the bone to allow proper distraction to take place. Correct functioning of the device was checked by distracting the bone fragment 1 mm using the axial distraction screw. A latency distraction healing screw was inserted in each of the distraction implants and the area was left to heal for 5 days. Once primary healing had occurred, the distraction of the newly formed bone callus was activated each day for 10 days (1 mm per day). At the end of the distraction period a final distraction screw was left in place and a final healing screw was inserted. During this lime there were no complications and the patient on no occasion complained of discomfort. The distractor device was removed 30 days late, leaving the base plugs in place. One month later a vertical augmentation of 7 mm had been achieved; the base plugs were removed, 3 intraosseous implants were inserted, and a biopsy of the newly formed tissue was obtained. Histologic evaluation of the biopsy specimen showed woven bone formation approximately 75 days after the initial procedure. [ABSTRACT FROM AUTHOR]

Six block grafts harvested from the mandibular symphysis were used to augment partially atrophied ridges. Three maxillary detects and three mandibular defects were treated in five patients. Autologous bone grafts from the chin were stabilized in the recipient sites with resorbable pins and no membranes were used over the grafts. Healing proceeded without complications. At 3 to 4 months the external cortical surface of the grafts progressively resorbed and the profiles of the pins protruded from underneath the buccal tissue that covered the augmented areas. However, the pins never perforated the tissue and they were resorbed macroscopically within 4 to 6 months. At 6 months the areas treated showed successful ridge augmentation and, when exposed for stage 2 surgery remnants of the pin holes on the external surface of the repaired defects were detected. Radiographic evaluation of the block grafts was performed at 3 and 6 months and histologic specimens were obtained at 6 months; the specimens demonstrated incomplete pin resorption and encapsulation. A severe foreign-body reaction was detected in, one case. The presence of an acellular bone matrix in certain sections and a normal bone pattern with a cellular component in others was a consistant finding. ITI endosseous implants were placed with excellent primary stability in all treated cases. [ABSTRACT FROM AUTHOR]

The clinical and histologic responses to periodontal treatment of gingival enlargements, induced when cyclosporine and nifedipine were administered singly or in combination, were evaluated. A significant correlation was noted between plaque, gingivitis, and gingival overgrowth, Severity of enlargement appeared to be greater in patients on combined therapy. All treatment approaches such as scaling, root planing, gingivectomy, and periodontal flaps, and a combination of therapies, were effective in the management of gingival overgrowth up to 1 year after completion of treatment. Adjunctive use of chlorhexidine was found to be beneficial. [ABSTRACT FROM AUTHOR]

Most electronic ballasts for fluorescent lamps provide a sinusoidal lamp current at the switching frequency. The high-frequency current flowing through the lamp can generate significant radiated noise, which is unacceptable in noise-sensitive applications, such as fluorescent lights in airplanes. Using shielded enclosures for the lamps may solve the problem, but it is expensive. A discontinuous conduction mode (DCM) electronic ballast topology is presented which drives the lamp with line frequency current, just like a magnetic ballast. However, compared to a magnetic ballast, its weight is substantially reduced due to operation at 40 kHz switching frequency. The topology also ensures unity power factor at the input and stable lamp operation at the output. Index Terms--Electromagnetic interference, electronic ballasts, power factor correction.