Interfacial bond strengths of amalgam bonded to amalgam and resin composite bonded to amalgam

A preparative method for the preparation of large peptides is described. An advantageous theoretical weight of peptide/weight of starting resin ratio (tPw/Rw) of about 0.3 was successfully experimented. The esterification of the first amino acid was realized with a racemization of less than 1%. The study of the coupling conditions led to the use of a diluted acylating mixture that allowed a 56% consumption of the amino acid derivatives (percentage use of amino acids) introduced in the synthesis. The cost analysis of the synthesis showed that the recovery of the amino acid derivatives was not worthwhile.     

Community alternatives to psychotherapy.

Increasingly, individuals are turning to and being confronted by alternatives to dynamically-oriented therapy. Among these alternative change systems are alternative therapies such as Alcoholics Anonymous, and alternatives to therapy, such as the spiritual approaches based on various meditations. There are important theoretical conflicts between dynamic therapy and these alternatives. However, combinations of dynamic therapy and these alternatives are being forged by consumers of mental health services. In their effort to maximize the delivery of help, consumers make pragmatic decisions to construct such combinations, ignoring or deemphasizing theoretical conflicts or viewing them within a framework of complementarity. Research on these combinations is needed to learn more about which are effective with whom and for what purpose. (26 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Shear bond strength of amalgam and gallium alloys to dentine

The purpose of this in vitro investigation was to determine the shear bond strength of admixed (Dispersalloy), irregular (Oralloy) and spherical (Lojic) amalgams, as well as an admixed gallium alloy (Galloy) to superficial, buccal, human dentine surfaces, using the Scotchbond Multi-Purpose Plus system. The bonds were stressed to failure in an Instron testing machine after 48 hours, and the following values (MPa) were obtained: Admixed = 7.74 +/- 0.7; Irregular = 9.47 +/- 1.4; Spherical = 9.82 +/- 2.4; Galloy = 11.03 +/- 2.5. Data were statistically analysed and fracture sites examined in a scanning electron microscope. Galloy demonstrated a statistical significant higher shear bond strength than to the other types of amalgams (p < 0.01).     

Shear bond strength of amalgam adhesives to dentin

Recent studies have suggested that failure of pentamidine prophylaxis against Pneumocystis carinii pneumonia (PCP) may be due to reduced deposition of pentamidine in the upper lobes. In this study, we performed bronchoalveolar lavage from the apical segment of the upper lobe and the middle lobe in 51 HIV-positive patients, all of whom were receiving prophylaxis with aerosolized pentamidine, who had presented with acute respiratory symptoms. Lavage fluid from each lobe was assayed for pentamidine using high-performance liquid chromatography (HPLC). The number of clusters of P carinii were counted after staining with a Wright-Giemsa stain. The patients were subclassified as PCP-positive (32 patients) and PCP-negative (19 patients) on the basis of the presence/absence of P carinii clusters in their BAL fluid. The concentration of pentamidine in the upper lobe compared with the middle lobe was no different (using paired Student's t tests) for either PCP-positive patients or PCP-negative patients. In comparing the positive with the negative subjects, using unpaired Student's t test, there was no difference in the concentration of pentamidine in the upper lobe or the middle lobe. For PCP-positive patients, the numbers of P carinii clusters were on average higher in the upper lobes (mean +/- SD: upper = 14.9 +/- 16.6, middle 7.5 +/- 10.8, p = 0.013, paired Student's t test), but there was no correlation between lobar P carinii cluster counts and pentamidine levels. We conclude that the absence of a relationship between cluster count and pentamidine level, the similarity in regional pentamidine levels between upper and middle lobes, as well as the similarity in pentamidine levels between the PCP-positive and PCP-negative groups indicate that the regional dose of pentamidine is not the determining factor as to whether aerosolized pentamidine prophylaxis will succeed or fail.     

Bonding of amalgam to composite: tensile strength and morphology study

OBJECTIVES: The present study was based on the premise that it may be possible to produce useful dental restorations by bonding freshly triturated amalgam to a cured composite restoration (Group 1 specimens), or by bonding uncured composite to hardened amalgam (Group 2 specimens). METHODS: To determine the validity of this premise, a phosphonate adhesive resin cement was used to produce simulated, layered dental restorations for each test group. RESULTS: The mean tensile bond strength of 24 hour-old Group 1 specimens (6.74 MPa +/- 1.63 MPa) was almost twice that of 24 hour-old Group 2 specimens. Cohesive failure of the amalgam-substrate layer was a prominent feature of the fracture pattern of Group 1 specimens. On the other hand, rupture of all Group 2 specimens occurred mainly along the adhesive-amalgam interface. Findings from SEM examination of the layers of amalgam, adhesive cement, and resin composite of intact Group 1 specimens suggested that inclusions of adhesive resin cement may be the cause of the persistent cohesive failure of the amalgam layer. SIGNIFICANCE: It may be possible to improve the strength of bonded couples made from freshly triturated amalgam and cured resin composite by minimizing the thickness of the adhesive layer.     

Mercury and dental amalgam fillings

During 1993-95 a total of 169 patients (112 women, 57 men) with a wide range of complaints associated with earlier or present amalgam fillings were seen by the "Dental Biomaterials Adverse Reaction Unit" in Norway. Most patients had amalgam fillings; 19 had removed all amalgam, and 14 were in the process of replacing the amalgam fillings with other materials. Predominant symptoms were of a subjective and general nature (96% of the patients). Muscle and joint pain, headache, dizziness and feeling exhausted comprised the most common symptoms. Intra-oral pathology was observed in 48%. There was a correlation between the amount of amalgam ("amalgam score") and urinary mercury. Those without amalgam fillings and significantly lower values (median = 1.6 micrograms mercury/g creatinine) than those with amalgam fillings (medians: with amalgam = 3.5 micrograms/g; with partial removal of amalgam = 2.7 micrograms/g). Overall, in the present group of patients, no statistically significant correlation seemed to exist between the type and number of subjective symptoms or objective findings and the urinary mercury. This would indicate therefore that there is no straightforward association between urinary mercury and symptoms in the present group of patients.     

Advantages and disadvantages of lateral preference.

Reviews the book, Lateral Preferences and Human Behaviour by Clare Porac and Stanley Coren (1981). This book contains a wealth of information and detailed discussion on lateral preferences in human beings. Previously, Porac and Coren have been responsible for the only really systematic surveys of handedness in relation to the other lateral preferences, andsidedness in relation to such variables as sex, age, medical history, cognitive abilities, motor skills, and social and cultural factors. In the main, the book is a review of this work, though it also contains lucid accounts of physiological and cerebral asymmetries and an especially clear and informative account of single- and multi-gene explanations of lateral preference. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Indentation creep behavior of a direct-filling silver alternative to amalgam

Amalgam creep has been identified as a key parameter associated with marginal breakdown and corrosion. The aim of this study was to evaluate the time-dependent deformation (creep) of a novel silver filling material as an alternative to amalgam. We made the silver specimens by pressing a precipitated powder at room temperature to a density that can be achieved in clinical hand consolidation. The surface of the silver was either polished or burnished. To examine local contact creep and the effect of surface finishing, we used an indentation creep method in which a Vickers indenter was loaded on the specimen surface at a load of 10 N with dwell times of 5 sec to 6x10(4) sec. We used a bonded-interface technique to examine subsurface creep mechanisms. The flexural strength (mean+/-SD; n = 10) was 86+/-20 MPa for amalgam, 180+/-21 MPa for polished silver, and 209+/-19 MPa for burnished silver-values which are significantly different from each other (family confidence coefficient = 0.95; Tukey's multiple-comparison test). Indentation creep manifested as hardness number decreasing with increased dwell time. With dwell time increasing from 5 sec to 6x10(4) sec, the hardness number of amalgam was reduced by approximately 80%; that of the polished silver and the burnished silver was reduced by only 40%. Subsurface creep in amalgam consisted of the shape change of the alloy particles from spherical to elongated shapes, and the separation of matrix grains from each other, possibly due to grain-boundary sliding. Creep of the polished silver occurred by densification reducing porosity and increasing hardness; that of the burnished silver occurred by the displacement of the burnished layer. These results suggest that, due to creep-induced subsurface work-hardening and densification, the consolidated silver exhibits a higher resistance to indentation creep than does amalgam. The hardness number of silver approaches that of amalgam after prolonged indentation loading.     

Inattentive and contented: Relationship commitment and attention to alternatives.

Commitment to a relationship is affected by the quality of one's alternatives to that partnership, but one must be aware of those alternatives in order for them to be influential. In a study of the links between attention to one's alternatives and relational outcomes, participants described their relationships, inspected slides of attractive opposite-sex targets, and, 2 months later, reported whether their relationships had ended. Satisfaction with, investment in, commitment to, and adjustment in a dating relationship were negatively correlated with reports of vigilance toward desirable alternatives to that relationship. In the lab, those who had earlier claimed to be attentive to alternatives really did spend more time inspecting pictures of attractive opposite-sex targets. Moreover, there was no better predictor of relationship failure than high attentiveness to alternatives. Inattentiveness may be a maintenance mechanism that helps to preserve and protect desirable relationships. Even if the grass is greener on the other side of the fence, happy gardeners will be less likely to notice. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Are there alternatives to traditional polygraph procedures?

The most commonly used method for detecting deception is based on the assumption that lies given by a person in response to critical questions posed during a polygraph examination will elicit an identifiable pattern of autonomic reactivity. Critics of this method argue that a polygraph examination cannot detect lying because lying does not produce a distinct physiological response. They assert that the possession of information only the guilty person would be expected to have can be revealed in a polygraph examination, however, by the pattern of autonomic arousal presentation this information elicits in a person who possesses it. In this article, the position is taken that the dependence of both procedures on autonomic measures diminishes their effectiveness and inhibits the development of alternatives. A few studies are reviewed that suggest that measures of brain electrical activity can be used to infer the possession of information in persons attempting to conceal it. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

The science and politics of dental amalgam

OBJECTIVE: To evaluate the effectiveness of pediatric practice consultation in reducing missed-opportunity rates at eight pediatric sites in Baltimore, Maryland. The overarching goal was to decrease the occurrence of missed opportunities from 33% to 15% for the first, second, and third diphtheria and tetanus toxoids and pertussis vaccines during visits at which children were eligible for the vaccines. DESIGN: The effect of an in-office educational program alone at four sites is compared with the educational program and a consultation on office vaccination practices at four matched sites. All eight sites received a small grant ($2,000) to fund practice changes. The medical records of children making visits before and after the interventions were audited to determine missed-opportunity rates. The policies and operations and the knowledge, attitudes, and practices of physicians and nurse practitioners at each site were also assessed. RESULTS: The four education-consultation sites experienced a statistically significant 14% net reduction in the missed-opportunity rate relative to the education-only sites. This positive effect, however, was largely due to an increase in missed opportunities at one education-only site. There was a 10% increase in the missed-opportunity rate among the education-only sites and a 4% decrease among the education-consultation sites; neither change was statistically significant. Two of the three sites that reduced missed opportunities were matched health maintenance organizations (HMOs). Shortly after the interventions, both HMOs implemented tracking and follow-up information systems, which were planned before the interventions. CONCLUSIONS: There is no evidence that either the educational program alone or the educational program and consultation combination reduced missed opportunities. The findings suggest that improved tracking and follow-up data systems and vaccination of children at sick visits may reduce missed opportunities.