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Biomedical subjects

R G Triplett

Publications and source records attributed to R G Triplett.

At least 37 records · Page 2Linked to original sources
PubMed1990

Life-threatening hemorrhage from placement of a dental implant.

This report focuses on a potentially fatal hemorrhage arising from dental implant placement in the mandible. Anatomic considerations of the lingual artery and its divisions in the floor of the mouth are discussed. In addition, various methods of controlling bleeding from the floor of the mouth are reviewed. The case presented is unusual in that intraoral ligation of the transected vessel was possible despite the presence of massive sublingual, submental, and submandibular hematomas as well as severely distorted anatomy. This case represents a severe complication resulting from a seemingly minor oral surgical procedure. Those performing endosteal implant placement should be knowledgeable in the management of such complications.

Arteries↗
PubMed1990

Immediate fixture placement: a treatment planning alternative.

The rationale and possible clinical applications of an immediate fixture placement technique are described. Although this concept may be a somewhat radical departure from the conventional mandibular protocol, there are significant potential patient benefits with no apparent change in anticipated fixture survival rates. A similar approach in the maxilla may be less practical with most presenting dentitions, but there is evidence that further research may make immediate fixture placement equally appropriate in this arch.

Alveolar Bone Loss↗
PubMed1989

Heart contains receptors for dihydrotestosterone but not testosterone: possible role in the sex differential in coronary heart disease.

The sex differential in coronary heart disease is well documented but poorly understood. Previous studies have demonstrated receptors for dihydrotestosterone (DHT) in the myocardium and smooth muscle cells of arteries from a number of species. In this autoradiographic study, we further investigated and characterized the in vivo uptake and retention of the androgen binding in the male baboon. Adult castrated male baboons were injected with 1 micrograms/kg bw 3H-testosterone; 1 hr after the injection, the animals were rapidly exsanguinated while under anesthesia. The heart and arterial system were removed and processed for autoradiography. As a negative control, one animal received both 3H-testosterone and 100-fold unlabeled testosterone. For positive controls, the pituitary gland, prostate, seminal vesicles, and other tissues were also removed and processed for autoradiography. In contrast to our previous finding with 3H-DHT, no nuclear uptake and retention of 3H-steroid was found in any of the cells in either the heart or the arterial system. In the positive control tissues, pituitary gland, prostate, seminal vesicles, and others, a very distinct nuclear uptake and retention of 3H-steroid was observed, which was completely inhibited by the simultaneous injection of 100-fold unlabeled testosterone. In the binding study, Scatchard analysis of the cytosol prepared from a 17-year-old female baboon demonstrated levels of androgen receptor (as determined by the use of radiolabeled R1881) comparable to that found in young adults.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1989

The effect of local antibiotics in treating chronic osseous Staphylococcus aureus infection.

The purpose of this study was to determine if antibiotic-supplemented bone allografts (ASBA) would enhance healing and reduce infection in chronic osteomyelitis. Intramedullary injection of Staphylococcus aureus was used to create osteomyelitis in the tibia of New Zealand white rabbits. Twenty-one days postinoculation, the animals were randomly assigned to one of the following six treatment groups: 1. debridement of the infected tibia; 2. debridement + bone graft; 3. debridement + bone graft + gelatin powder; 4. debridement + bone graft + gelatin powder supplemented with antibiotics; 5. debridement + gelatin powder supplemented with antibiotics; and 6. no surgical intervention. The debrided material was cultured for identification of microorganisms. All groups received cephalothin sodium, 100 micrograms/kg subcutaneously every 12 hours for 21-days. At time of death the tibia were assessed to determine the degree of healing. Radiographs, bacterial cultures and specimens for histologic study were obtained. Qualitative grading demonstrated a significant difference between groups (P less than .001). Groups (4 and 5) receiving local antibiotic supplementation demonstrated improved healing compared with the remaining groups. However, there was no difference between groups 4 and 5. Bacteriologic culturing indicated the greatest reduction in colony-forming units of S aureus in the postsacrifice graft sites to be in groups 4 and 5. Histologic findings paralleled qualitative assessment of healing of the gross specimens. The results of this study suggest that local antibiotic supplementation of graft preparations may be useful for treatment of chronic osseous infection.

Animals↗
PubMed1989

Antibody response to Staphylococcus aureus surface proteins in rabbits with persistent osteomyelitis after treatment with demineralized bone implants.

A rabbit model was used to study the effect of allogeneic demineralized bone powder (DBP) implants on the persistence of Staphylococcus aureus osteomyelitis. Thirty-one rabbits with chronic osteomyelitis of the tibia established by day 21, were started on systemic antibiotics followed by either no additional treatment or debridement plus either DBP (with or without supplemental antibiotics) or supplemental antibiotics only. On day 21, cultures showed a mean of 2 x 10(4) CFU/mg of debrided osseous material. By day 70, the treatment most effective in clearing infection was found in animals treated with supplemental antibiotics only (mean of 142 +/- 116 CFU/mg). In contrast, infection persisted at a 7- to 10-fold-higher level in animals receiving DBP with and without supplemental antibiotics; these results suggest that DBP contributed to persistence of infection. Longitudinal sera were tested again staphylococcal sonic extracts by immunoblot. Detection of numerous probe-positive bands indicated complex but remarkably similar antibody responses among infected animals. Antibodies attached directly to the cell surfaces of staphylococci as shown by immunogold and blocked the binding of organisms to HEp-2 and human fetal lung cells in a radioadherence assay. Antibodies could be absorbed out by intact organisms and were unreactive by immunoblot against antigens derived from cells pretreated with pronase, proteinase K, or lysostaphin. These results indicate that the major response was directed against staphylococcal cell surface proteins. Surprisingly, only one major band (molecular weight, approximately 12,000) was detected when a homologous in vivo antigen preparation was studied by immunoblot. Antibody reactive against this peptide did not appear to react with staphylococci grown in vitro.

Animals↗
PubMed1988

A differential nuclear uptake and retention of 3H-androgens in the thyroids of baboons.

Women have a greater incidence of autoimmune thyroiditis, thyroid cancer and radiation-induced carcinogenesis than men. Over the past several years we have examined for the presence of steroid receptors in both humans and non-human primates. In this study we examined the nuclear uptake and retention of 3H-testosterone, the main circulating androgen in mammals, in different cells of the thyroid gland of baboons, our non-human primate model. Castrated-adrenalectomized male baboons were injected with 3H-testosterone (1 microgram/kg bw) and killed 1 1/2 h later. The thyroid glands and other tissues were removed and processed for autoradiography. Nuclear localization of 3H-testosterone or one of its metabolites was found in a small fraction of the follicular cells (approximately 10-20%). The discrepancy between these findings and those previously obtained with 3H-dihydrotestosterone (virtually 100% of the follicular cells concentrated the 3H-steroid) are discussed. The results from this study and those of the past strongly support a direct action of androgen on the thyroid. Whether a direct action of androgen on the thyroid is related to smaller incidence in autoimmune thyroiditis, thyroid cancer and radiation-induced carcinogenesis in men than women remains an unanswered question at the present time.

Androgens↗
PubMed1988

The role of bacterial-laden biofilms in infections of maxillofacial biomaterials.

Biomaterials from 11 consecutive patients with persistent infections refractory to antimicrobial therapy and local wound care were surgically removed and studied by scanning electron microscopy for the presence of bacterial-laden biofilms. Unlike previously reported biomaterial infections involving other regions of the body, infections in this study were not associated with a conspicuous bacterial-laden biofilm. Instead, adherent light bacterial colonization without a biofilm layer was noted. The only specimen that was suggestive of a bacterial-laden biofilm was in a patient who suffered from a chronic infection. Consistent with previous reports, bacterial colonization was frequently polymicrobial. Observations made in this study suggest that bacterial adherence may not require an obvious biofilm layer.

Adolescent↗
PubMed1987

Sexual dimorphism in the distribution of estrogen receptors in the temporomandibular joint complex of the baboon.

The localization of radiolabeled estradiol was examined in the temporomandibular complex of male baboons by means of an autoradiographic technique. Five baboons were studied. Four animals received only the tritiated estrogen (1 microgram/kgm) and one animal, which served as the control, received both the tritiated estrogen and the unlabeled estrogen (100 micrograms/kgm). The study failed to demonstrate nuclear uptake and retention of tritiated estrogen in any of the tissues of the temporomandibular joint complex, including the articular surface of the condyle, articular disk, capsule, and muscles of mastication. However, estrogen receptors were identified in other tissues, including the pituitary. All tissues examined in the control animal were negative for estrogen receptors. It was concluded that there were no estrogen receptors in the temporomandibular joint complex of aged male baboons. As in previous studies, these findings provide additional evidence of a sexual dimorphism with respect to estrogen receptor distribution in the temporomandibular joint complex of the baboon. Furthermore, it is reasonable to speculate that estrogens may modulate a variety of metabolic functions in these tissues that could be important in the maintenance, repair, and/or pathogenesis of the temporomandibular joint.

Animals↗
PubMed1987

Intraosseous wire fixation versus rigid osseous fixation of mandibular fractures: a preliminary report.

While wire osteosynthesis has been the accepted modality to use with open reduction of mandibular fractures, several authors have suggested the use of more rigid techniques to achieve the same result while also eliminating adverse effects associated with prolonged maxillomandibular fixation. Few studies have directly compared the two techniques in a prospective manner. The purpose of this paper was to evaluate complications seen with wire osteosynthesis versus a small bone plating system in management of mandibular fractures. The results suggest that small bone plating systems similar to the one used in this study may serve as a suitable alternative to wire osteosynthesis for the management of mandibular parasymphysis, body, and angle fractures. The length of the procedure, the length of hospital stay, and patient comfort were comparable with the two techniques. Factors that may contribute to failure are: location of the fracture, poor patient compliance, length of time from the trauma to the repair, antibiotic choice, and most importantly, operator skill and experience.

Adolescent↗
PubMed1987

Effect of pretreatment with acetaminophen-propoxyphene for oral surgery pain.

To determine the effect of pretreatment and multiple doses on postsurgical pain, a study of the relative analgesic efficacy of placebo, acetaminophen 650 mg, and propoxyphene napsylate 100 mg alone and in combination was conducted. Forty-five patients undergoing surgical removal of impacted third molar teeth under local anesthesia were randomly allocated to the four treatment regimens under double-blind conditions. The first oral dose was administered one hour preoperatively and the second dose when the pain became moderate or severe, following the dissipation of the local anesthesia. Pain intensity and pain relief were assessed using standard verbal descriptor scales at 30 minutes and hourly for four hours after the postoperative dose. Measures of total effect, peak effect and duration of their effect were derived from these descriptors. Acetaminophen was no better than placebo. For peak and total effects, propoxyphene alone and the propoxyphene-acetaminophen combination were substantially superior to both placebo and acetaminophen alone. Duration of analgesia was also significantly longer with both propoxyphene-containing treatments. No side effects were reported. The results suggest that pretreatment with a narcotic agonist markedly improves postoperative analgesia.

Acetaminophen↗
PubMed1986

Predictability of maxillary surgery: a comparison of internal and external reference marks.

Internal reference lines have traditionally been used to correlate model work with maxillary surgery. An external point of reference has been suggested for more accurate positioning of the maxilla during surgery. This study compared the predictability of two groups of patients undergoing Le Fort I maxillary osteotomies with either internal reference lines or an external reference point. In the group in which an external reference point was employed, the position of the maxillary central incisor was more accurately predicted on both the x and y coordinates (p less than 0.01) than in the group in which internal reference lines were placed.

Cephalometry↗
PubMed1985

Effect of preoperative cimetidine and ranitidine on gastric secretion.

To decrease gastric volume and acidity prior to anesthesia and surgery and decrease the risk of aspiration, a prospective double-blind trial comparing two H2 receptor blockers, cimetidine and ranitidine, was performed. Analysis of gastric contents revealed both drugs to be extremely effective in raising gastric pH to the 6-7 range. However, ranitidine was shown to be more effective in decreasing gastric volume.

Administration, Oral↗
PubMed1985

The effect of electrical current on the healing of mandibular freeze-dried bone allografts in dogs.

Low levels of electrical current have been shown to affect the process of osseous repair. This study experimentally evaluated the effect of electrical stimulation on the healing of freeze-dried mandibular allogeneic bone grafts in dogs. Healing of the grafts was monitored by sequential submento-occlusal radiographs and radionuclide bone imaging at two, four, six, and eight weeks after grafting. Results indicated no significant difference in the osseous repair of stimulated and nonstimulated freeze-dried allogeneic bone grafts.

Animals↗
PubMed1983

The effect of chronic red cell mass depletion on the healing of bone grafts.

The purpose of this study was to determine whether a marked decrease in red cell mass with a normal blood volume (normovolemic anemia) would compromise osseous repair in experimental mandibular bone grafts. In adult male dogs, osseous defects in the mandibular body were restored with combined allogeneic and autologous bone grafts. In the experimental group, the red cell mass was depleted by a mean 55% of the baseline value and the resulting anemia maintained for eight weeks by serial phlebotomies. In the control group phlebotomy was not performed. Osseous repair was evaluated by quantitative sequential radionuclide imaging, subjective and quantitative determinations of graft stability, and histologic examination. Results demonstrated no significant difference in bone graft repairs between the anemic and control animals by any of the evaluation methods over the eight-week period of study (P greater than 0.05).

Anemia↗
PubMed1983

Comparison of fresh autogenous and freeze-dried allogenic skin for mandibular vestibuloplasty.

This study compared the ability of fresh autogenous and freeze-dried allogenic split-thickness skin grafts to maintain vestibular depth following vestibuloplasty. Both graft systems resulted in covering of the alveolar ridge by firmly attached tissue, which would be expected to enhance prosthetic stability. The appearance of the fresh autogenous grafts was consistent with that of mature skin grafts, whereas the freeze-dried grafts had the appearance of alveolar mucosa. Vestibular depth stabilized at six weeks with both graft systems, and at six months there was no significant difference (P less than 0.05) between the freeze-dried and fresh grafts with respect to their ability to maintain vestibular depth.

Animals↗
PubMed1983

A simplified technique for the evaluation of circulation in experimental osseous grafts.

A technique has been described that is effective in the evaluation of microcirculation in experimental bone grafts. This method employs India ink with a perfusion pump. These materials provide an inexpensive, rapid, and simple protocol that yields consistent, repeatable results with graphic demonstration of microcirculation in experimental bone grafts.

Animals↗