A pilot study to evaluate different palate materials for maxillary complete dentures with xerostomic patients.

PURPOSE: The hypothesis tested in this pilot study was that materials used for the palatal region of a maxillary denture affect the comfort of the maxillary denture in xerostomic patients. MATERIALS AND METHODS: Xerostomic complete denture wearers were selected to test three different maxillary dentures that were made with different palatal materials. Each denture was worn for a period of 2 weeks. The Kapur Index was used to measure retention. The Oral Health Index Profile (OHIP) was used to determine the patient's perception of each denture after the 2-week period. At the end of the study, the patients were asked to select which of the three dentures they would like as their primary denture. RESULTS: All participants chose the metal-palate dentures, and 4 of 5 selected the titanium-palate denture as their primary denture. Statistical analysis of the OHIP demonstrated that the metal-palate dentures were perceived as being more comfortable than the acrylic-resin dentures. CONCLUSION: This pilot study suggests that for xerostomic patients who have worn complete dentures, their selection of a metal-palate denture as their primary prosthesis strongly suggests that these dentures have properties that make them more comfortable to the patient than acrylic dentures. Subjective patient measurements supported this conclusion that the metal-palate dentures were preferable, while the evaluation method available to the clinician failed to discriminate among the prostheses.

Comparison of titanium and cobalt-chromium removable partial denture clasps.

STATEMENT OF PROBLEM: The use of titanium alloys for removable partial dentures is an increasingly popular application. While the flexibility of titanium would allow for cast clasps to be placed in deeper undercuts than advisable with cobalt-chromium, it is possible that the retentive forces of the titanium clasp might not maintain sufficient retention after repeated flexing of the clasp arm during insertion and removal of the partial denture. PURPOSE: This study assessed the characteristics of cast clasps made of titanium and titanium alloys to determine whether these materials are suitable alternatives for removable partial denture applications. MATERIAL AND METHODS: Removable partial denture clasps at two undercut depths were fabricated from commercially pure titanium, titanium alloy (Ti-6A1-4V), and cobalt-chromium. Loss of retention force was measured as the clasps underwent 3 years of simulated clinical use. The data were subjected to ANOVA and Scheffé's tests to determine differences. Evidence of casting defects and porosity was evaluated by radiographic examination and nonparametric statistics. SEM microscopy was used to observe surface characteristics that were described qualitatively. RESULTS: For the 0.75 mm undercut specimens, there was less loss of retention for clasps made from pure titanium and titanium alloy than for cobalt-chromium clasps. Porosity was more apparent in the pure titanium and titanium alloy clasps than in those made from cobalt-chromium, but the amount of porosity did not correspond to evidence of fractures or permanent deformation. CONCLUSIONS: The long-term retentive resiliency of the pure titanium and titanium alloy clasps suggests that these materials are suitable for removable partial dentures.

Surface treatment of indirect resin composite surfaces before cementation.

STATEMENT OF PROBLEM: Controversy surrounds the use of hydrofluoric acid to prepare precementation surfaces of indirect composites. PURPOSE: This study was conducted to compare effects of combining hydrofluoric or orthophosphoric acid with microetching as precementation treatments. MATERIAL AND METHODS: Nine specimens of three composite materials were prepared to simulate heat-cured indirect restorations. The specimen surfaces were prepared with one of three treatments. Adhesive Bond II and Twinlook cements were used to bond a phosphoric acid-etched disk of P50 to the treated surface. Analysis of variance and Scheffé tests were used to assess the bond strength data. Scanning electron microscopy and microscopic analysis of the fractured and treated surfaces were also performed. RESULTS: Bond strengths for all surface treatments did not significantly differ. Hybrids had a higher bond strength with etching than microfills, and mechanical roughening produced the greatest bond strengths with microfills. Microetching with orthophosphoric acid produced higher bond strengths than microetching with hydrofluoric acid on hybrids. CONCLUSIONS: Acid etching alone is not sufficient to produce effective bond strengths, and hydrofluoric acid treatments are detrimental to the resin composite.

A comparison of two silicoating techniques.

PURPOSE: A major challenge of composite-coated metal restorations is creating a strong bond between the two materials. This study was conducted to compare the bond strengths between composite and metal alloys using two silicoating treatments; the Silicoater Classic and the Silicoater MD (Kulzer Inc, Irvine, CA). MATERIALS AND METHODS: The Classic uses a pyrolytically applied silica glass and the MD process is an oven sintering of a metal oxide silicate layer. Two types of specimens of three different alloys were cast (Deva4: 51Au38Pd, G-Cast: 50Au32Ag12Cu [Degussa Corp. South Plainfield, NJ]; Ticonium: 70Ni15Cr [CMP Industries, Inc, Albany NY]). The specimens were silicoated with either the Classic or the MD process and opaque resin and composite (Dentacolor, Kulzer Inc) were bonded to each surface. A total of five control and 10 thermocycled (5,040 cycles 0 degree C to 67 degrees C; dwell time, 1 minute) specimens were fabricated for each alloy and specimen type. Two bond strength tests were used; a three-point flexure test and a shear bond strength test. Data were analyzed using a multivariate analysis of variance (MANOVA) and a Tukey's multiple comparison test. RESULTS: The standard deviations of the shear bond strength values ranged from +/- 2.30 to +/- 17.82.kg; thus, there was no significant difference in these results. Bond strength ratios were calculated from the flexure strength data. After thermocycling, the Silicoater MD produced significantly higher (P < 0.05) bond strength ratio values compared with the Silicoater Classic for Deva-4 (MD, 9.6 +/- 1.5 v Classic, 4.7 +/- 0.9) and G-Cast (MD, 11.6 +/- 1.2 v Classic, 3.9 +/- 0.5) but lower values for Ticonium (MD, 4.5 +/- 0.4 v Classic, 6.9 +/- 0.9). CONCLUSION: The Silicoater MD produced higher bond strength ratio values with noble alloys, and the Silicoater Classic produced higher bond strength ratio results when base metal alloys were used, suggesting a possible correlation between the effectiveness of the coating processes and the compositions of the alloys. These findings suggest that, for optimum results, selection of the type of silicoating process should be based on the components of the alloy.

Cerebral vasospasm: current concepts of pathogenesis and treatment.

It is believed that most patients with subarachnoid hemorrhage secondary to aneurysmal rupture experience some degree of cerebral vasospasm, although not all develop specific neurologic deficits. Management is complicated, and at present the outcome is often less than optimal. This article reviews the symptoms, predictors and pathophysiology of vasospasm, highlighting current theories of pathogenesis as well as their relationship to treatment. This information is essential for the neuroscience nurse to care adequately for these patients. A plan of care for the patient with cerebral vasospasm is included.

Alveolar phospholipids of 17-day-old pigs exposed to microorganisms of nonpulmonic origin.

Alveolar lining material was obtained from gnotobiotic pigs; gnotobiotic pigs exposed to aerobes, anaerobes, or mixtures of both microorganisms; and conventional farm-raised pigs. Alveolar lining material concentrations of phosphatidylcholine, sphingomyelin, phosphatidylserine, phosphatidylinositol, phosphatidylethanolamine, phosphatidylglycerol, and lysolecithin were determined. Seventy-four pigs were allotted to the following groups: 1--gnotobiotes (n = 13), 2--gnotobiotes with aerobes (n = 6), 3--gnotobiotes with anaerobes (n = 31), 4--gnotobiotes with anaerobes and aerobes (n = 2), 5--gnotobiotes with facultative anaerobes (n = 9), and 6--conventionally farm-farrowed (n = 13). The conventionally raised pigs had lysolecithin, sphingomyelin, and phosphatidylinositol concentrations that were significantly different from those of all other groups of pigs. Phosphatidylethanolamine was significantly decreased in group 6 pigs when compared with that in all other groups. There were also statistically significant differences between the gnotobiotic (group 1) and the exposed gnotobiotic (groups 2, 3, 4, 5) pigs, although the differences were less pronounced. Since intestinal microbes produce alveolar lining material phospholipid differences, studies need to be concerned with phospholipid changes that occur after exposure to lung-specific microorganisms and with physiologic changes in lung function associated with the phospholipid changes.

Xylazine-induced hyperglycemia in cattle: a possible involvement of alpha 2-adrenergic receptors regulating insulin release.

The mechanism by which xylazine raises plasma glucose but lowers insulin concentrations was examined in Holstein cows. Intravenous injection of xylazine (15-150 micrograms/kg) induced a dose-dependent hyperglycemia and hypoinsulinemia for 3-4 h. An alpha 2-adrenergic blocking agent, yohimbine, and an alpha 1- and alpha 2-adrenergic blocking agent, phentolamine, at 500 micrograms/kg each reduced or abolished xylazine-induced hyperglycemia and hypoinsulinemia. The alpha 1-adrenergic blocking agents, prazosin and phenoxybenzamine, at 500 micrograms/kg each did not exert such antagonism. Prazosin at the dose studied even prolonged xylazine-induced hypoinsulinemia. The alpha-adrenergic blocking agents alone at 500 micrograms/kg each did not change either plasma glucose or insulin concentrations. The present study suggests that xylazine-induced hyperglycemia and hypoinsulinemia are mediated by alpha 2-adrenergic receptors, possibly in beta-cells of pancreatic islets which inhibit the release of insulin. The present study further suggests the use of xylazine as a pharmacological tool in the study of adrenergic influence on in vivo insulin release.