Cell response to hyperbaric oxygen treatment.

Wound healing involves matrix deposition, angiogenesis, and new tissue growth. Cellular activity during healing is related to tissue oxygen levels. Since wound healing requires oxygen, the purpose of this study was to investigate the effects of hyperbaric oxygen (HBO) on cells involved in wound healing. Cultured endothelial cells and fibroblasts were exposed to HBO. The effect of varied partial pressure, oxygen saturation, and duration and frequency of exposure to HBO on cell proliferation was determined by 3H-labeled thymidine incorporation. HBO causes an increase in the partial pressure of oxygen in the medium of cultured cells, leading to increased endothelial cell and fibroblast proliferation. Increased endothelial cell proliferation occurred after 15 min of HBO. Fibroblasts required 120 min of HBO to produce a response. A second exposure to HBO on the same day produced no additional increase in cell proliferation. A 120-min HBO exposure stimulated fibroblast proliferation for 72 h after the exposure. An increase in pressure from 2.4 to 4.0 atmospheres absolute did not enhance the proliferative response. These studies begin to elucidate the effects of HBO on cells involved in wound healing and establish a scientific foundation upon which to develop more efficacious and cost-effective HBO therapeutic protocols.

Transdifferentiation of chicken embryonic cells into muscle cells by the 3' untranslated region of muscle tropomyosin.

Transfection with a plasmid encoding the 3' untranslated region (3' UTR) of skeletal muscle tropomyosin induces chicken embryonic fibroblasts to express skeletal tropomyosin. Such cells become spindle shaped, fuse, and express titin, a marker of striated muscle differentiation. Skeletal muscle tropomyosin and titin organize in sarcomeric arrays. When the tropomyosin 3' UTR is expressed in osteoblasts, less skeletal muscle tropomyosin is expressed, and titin expression is delayed. Some transfected osteoblasts become spindle shaped but do not fuse nor organize these proteins into sarcomeres. Transfected cells expressing muscle tropomyosin organize muscle and nonmuscle isoforms into the same structures. Thus, the skeletal muscle tropomyosin 3' UTR induces transdifferentiation into a striated muscle phenotype in a cell-type-specific context.

Orthodontic considerations in orthognathic surgery.

It is important for the oral and maxillofacial surgeon to understand the orthodontic decision-making process as it pertains to the orthognathic surgery patient to facilitate interprofessional communication. The orthodontic diagnostic process integrates the needs of the dentition, the requirements of facial balance, and the constraints of orthodontic mechanics to arrive at the best collective recommendation in each case. The orthodontic treatment objectives, extraction patterns, and types of mechanics used in orthognathic surgery cases may vary from those used in nonsurgical orthodontic regimens, in which the dentition is considered in the context of the largely immutable skeletal pattern. The goal of presurgical orthodontic treatment is to prepare the dentition for maximal surgical correction so that, at the time of surgery, the dental arches are compatible with the postsurgical position and facial balance is achieved.

Coordination of the orthosurgical treatment program.

Health care reform, current changes in the third-party payer system, and the evolution of orthognathic surgery mandate superior communication between the oral and maxillofacial surgeon and orthodontist. This article describes a successful approach to coordinating the entire orthosurgical treatment program to improve treatment outcome and patient satisfaction.

Long-term follow-up of the use of nonporous hydroxyapatite for augmentation of the alveolar ridge.

Particulate hydroxyapatite (HA) was used in the augmentation of 18 mandibular and four maxillary ridges in 21 patients whose cases were followed postoperatively for 5 to 7 years. Patients were evaluated clinically, radiographically, and through questionnaires. Prosthodontic assessment of retention and stability of dentures showed improvement 5 years postoperatively. Patients receiving HA rated their dentures favorably using parameters of the Cornell Medical Index. The results of this study show that particulate HA alone can be used as a satisfactory material for augmentation of the alveolar ridge.

Porous hydroxylapatite granules and blocks as alveolar ridge augmentation materials: a preliminary report.

Porous hydroxylapatite (PHA) blocks and granules were used in the augmentation of 30 maxillary and mandibular ridges in 28 patients. The postoperative evaluation period was 2 years in all cases. The patients were evaluated clinically and radiographically, and by patient questionnaires. An increased incidence of dehiscence was noted with the blocks as compared with the granules. Overall prosthodontic assessment showed 95% improvement among the granule cases when compared with the preoperative ridge, and 88% improvement noted among the block cases. Patient rating of their general satisfaction with their dentures showed 82% improvement in the granule patients, and 55% in the block cases. Radiographically, the granules showed an average decrease of 8%. The results of this study show that PHA granules can be used as satisfactory alveolar ridge augmentation material, while the blocks show an increased number of complications and should be used only in very selected cases.