摘要:

SummaryA dysfunctional occlusal relationship was produced in six Macaca irus monkeys by insertion of occlusal splints which raised the vertical dimension of occlusion by 3–4 mm and incorporated interferences into the occlusion. Cortisol levels of plasma and 24 h urine samples were measured by competitive protein‐binding analysis. After insertion of the splints there was an immediate, approximately two‐fold rise of the mean 24 h urinary cortisol excretion rate and a significant decrease of urinary volume and body weight. The plasma cortisol level did not rise significantly. During the 3 weeks experimental period the teeth showed increasing mobility and occlusal wear facets developed on the splints. Urinary cortisol excretion rates were significantly elevated throughout the experimental period. Urinary cortisol levels declined to basal values when the splints were removed. This animal model produces experimental evidence in support of the hypothesis that a dysfunctional occlusal relationship may result in bruxism associated with emotional s

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00469.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryThe effect of accidental salivary contamination on the retention of fissure sealants is investigated via in Vitro bond tests and scanning electron microscopy. The strength of the bond between sealant and saliva contaminated and washed enamel (168 ± 14 kg cm−2) is not found to be significantly different from the bond strength to uncontaminated enamel (174 ± 17 kg cm−2). Unwashed contaminated enamel gives significantly reduced bond strength (68 ± 11 kg

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00470.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryToothpaste abrasivity should be sufficiently high to give effective cleaning without causing mechanical damage to tooth tissue. A clinical trial carried out to measure the cleaning power of calcium carbonate toothpastes of different abrasivity is described; cleaning power is then related toin vitrodentine abrasivity measurements. These findings are used to derive an expression specifying the toothpaste cleaning power which ensures that a chosen low and cosmetically acceptable level of stain is not exceeded providing a consistent daily brushing routine is adhered to.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00471.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryMaximal voluntary isometric contractions of the elevator jaw muscles, with the mandible in the position of maximal intercuspation of the natural teeth, can induce fatigue and weak as well as severe pains in the jaw muscles of children and adults. A subjective sensation of muscle fatigue appears after about 0.5 min of clenching, and it seems as if the psychological parameter of fatigue onset to a large, but unknown, extent is determined by the physiological parameter of the amount of isometric contractile activity, and perhaps also the original strength of the muscle; however, also individual psychological factors seem to play a role. Pains in the elevator jaw muscles appear after about 1 min of clenching. Although isometric contractions are necessary to cause onset of jaw muscle pains, it is conceivable that the perception of the moment of onset of pains to a large, but unknown, extent depends on psychological factors, perhaps the intensity of pains; however, also physiological factors may play a role. The severe muscle pains and gradually increasing subjective exhaustion of the elevator jaw muscles can be endured for about 2 min of maximal voluntary tooth clenching. It is suggested that the psychological parameter of muscle endurance to a large, but unknown, extent depends on the physiological parameter of isometric contractile activity, but also individual psychological factors seem to play a role.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00472.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryThe effect of incorporated CaF2(2.04%), NaF (2.27%) and amine fluoride (0.71%) in acrylic resin plates, on bending strength and fluoride release by rinsing and immersion in synthetic saliva, was determined. Bending strength was reduced by 6.7, 9.5 and 20% respectively. The most elevated release of fluoride from the NaF containing—and the most protracted from the CaF2containing—plates may be related to the solubilities of the compounds.It appears that the organic molecule of the AmF compound affects the strength of the acrylic plates most significantly.The F‐ concentrations released in thein vitrorinsing experiment may be presumed to occur in vivo at some higher level due to the larger size of dental appli

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00473.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryThe superior clinical performance of several dental amalgams which contain high Cu concentrations and little or no γ2 has stimulated the introduction of a number of new amalgam alloys. This investigation sought to study the nature of the phases present in eight commercial systems after trituration. Samples were powdered for X‐ray diffraction phase analysis or were polished for SEM/EDS analysis. These methods were complementary since they permitted positive identification of the phases and their distribution and composition, respectively.The matrix phase of all systems was γ1 (Ag‐Hg). Cu6Sn5was found as the major Sn‐rich amalgamation product. The Cu6Sn5phase forms reaction zones around the Cu‐rich particles with morphological variations from system to system. All amalgams contained the γ (Ag3Sn) phase, but it was microstructurally distinct only in two particle systems. Small amounts of the γ2 (Sn‐Hg) phase were found in three systems. These results suggest that there are important microstructural variations in the new Cu‐rich systems which could eventually result in variations in clini

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00474.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryThe rheological behaviour of six setting carboxylate cements was studied by capillary techniques in the shear rate of 0.65–65 s−1and the cements were found to behave as power law fluids. All cements became dilatant as setting progressed and the kinetics of apparent viscosity increase, were found to follow an exponential function of time, exp (mt), with m

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00475.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryThe rheological properties of two glass ionomer cements, ASPA and Fuji have been investigated. The viscosities of the liquid components of these systems have been found to be Newtonian up to a shear rate of 140 s−1with values of 0.80 N m−2s for ASPA and 1.8 N m−2for Fuji. Capillary viscometry techniques have been employed to study the rheological changes accompanying setting. Both cements appear to behave as power law fluids, becoming progressively dilatant as setting proceeds. The apparent viscosities of the two systems are approximately equivalent displaying values of the order of 50 Nm‐2s, at a shear rate of unity shortly after

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00476.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryResidual stresses in metal‐ceramic crowns were examined in three different ways. First, a mathematical formula was used to calculate the stresses in the cervical part of a crown. Second, plastic models was used where the strains were measured with strains‐gauges. Third, real crowns were used and strain gauges were attached on them. The results indicated that compressive stresses appeared in the porcelain‐metal interface. Compressive stresses were also found on the surfaces of the crowns and tensile stresses perpendicular to the inte

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00477.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryA four‐unit principal model bridge was used. The stresses in the porcelain part of an anchor crown were analysed. When the middle of the span was loaded tensile stresses appeared in the outer surface of the porcelain and compressive ones in the interface. Greater stresses were found when the anchor crown was loaded itself. They were not critical, however, when the gold thickness was>3 m

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00478.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY