摘要:

SummaryAttrition, or wear of the occlusal surfaces of the teeth, may not only be physiologically normal, but necessary for function. Since occlusal wear must lead to reduction in tooth length, significant dimensional changes in facial morphology are inevitable unless mechanisms exist to compensate for attrition. Secondary dentine formation, alveolar growth, and adaptive changes in the masticatory muscles can provide this compensation, and may be part of a complex system by which an effective level of masticatory function is maintained even when attrition is extreme.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00945.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SummaryRecent Swedish publications report that a large number of patients suffer from the mandibular dysfunction syndrome. Some theories assume that this syndrome is the result of a disturbance in blood flow through the maxillary artery.The present authors suggest, that the syndrome is caused by a disturbance in the pattern of contraction of the masticatory muscles. This hypothesis is based on the assumption that the human periodontal membrane contains mechanoreceptors which are able to exert reflex control over the pattern of contraction of the muscles during chewing.If the pattern of stimulation of these receptors is modified following dental restoration, then this could result in a disturbance of the neuromuscular pattern of the masticatory apparatus. In order to test this hypothesis, an electromyographic study was carried out in three volunteers and eight patients. The results of this study support the view that there are receptors in the human periodontal membrane which are able to control the pattern of contraction of the masticatory muscles.The hypothesis that the mandibular dysfunction syndrome is the result of a disturbance in the pattern of contraction of these muscles is pursued further in the discussion.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00946.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SummaryCharacterization of the pore structure of compacted and sintered parts made from a nickel‐base powder was accomplished using the mercury porosimetry method. The theoretical density values for the sintered specimens varied from 56.3 to 96.7% which corresponds to a porosity of 43.7 to 3.3%. A maximum interconnecting median pore diameter of 21 μm resulted from a −80/+ 200 mesh powder compacted at 138 MN/ m2and sintered for 2 h at 1250°C. Photomicrographs of the same sample showed that it had a maximum pore diameter of 200 μm. The interconnected pore volume decreased with decreasing particle size of the powder, increasing compaction pressure, and increasing sintering temperature. Mechanical properties of tensile strength, yield strength, elastic modulus and percentage elongation were correlated with the pore structure. Proper selection of particle size, compaction pressure, sintering times and sintering temperatures should permit parts with controlled porosity characteristics to be produced that possess adequate mechanical properties for application as im

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00947.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SummaryThe adaptation of amalgam fillings to the cavity walls has been studied. Cavities were made in human teeth and filled with four different amalgams: (1) amalgam with an expansion of approx. 10 μm/cm after 48 h; (2) amalgam with no dimensional change after 48 h (balanced); (3) amalgam with a contraction of approx. 10 μm/cm after 48 h; and (4) amalgam with a contraction of approx. 20 μm/cm after 48 h.The filling surface and parts of the surrounding enamel were planed, polished and studied under the microscope. The degree of contact between the amalgam and the cavity wall and the number and dimensions of the marginal defects were observed.Fillings made from expanding or balanced amalgams mostly had good contact with the cavity wall, and the marginal defects were small and scattered. Around fillings made from contracting material, a slit formation was observed, and in these areas fractures of both the amalgam and the enamel margins had regularly changed the slit to a V‐shaped gap 10–20 μm wide. Greater defects exceeding 50 μm were also frequently observed.The results showed a gradual decrease in the quality of adaptation from fillings made of expanding material to those made of contracting material. It was further shown that the polishing procedure caused fracturing of both the unsupported enamel and amalgam margins thus widening the defects cons

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00948.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SummaryThe oral hygiene, gingival condition, pocket depth and loss of attachment were studied during a period of 5 years in a group of patients (114) who had been treated with fixed dental protheses. Eighty‐four per cent of the subjects had received periodontal therapy prior to the prosthetic treatment. During the study the subjects participated in an oral hygiene programme.Crown margins were located sub‐gingivally, at the gingiva, and supra‐gingivally. Initially 65% of the crown margins were sub‐gingival compared to 41% 5 years later. When the crown margins were located sub‐gingivally there was an increase in Gingival Index scores 2 and 3, in pocket depth, and in loss of attachment compared to a supra‐gingival placement. However, most of the alterations

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00949.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SummaryPhosphoric acid at different concentrations has been extensively used as an etching agent to improve bonding of dental materials to enamel surfaces. Recently attention has been drawn to the possible use of polyfunctional organic acids as conditioning agents.The object of this investigation was to determine the optimal concentration of pyruvic acid as an etching agent. A commercial composite resin with an intermediary bonding system supplied with 37% H3PO4as an etching agent was used as the control system. In addition, a comparative study was carried out to evaluate 37% H3PO4, 20% lactic acid and the optimal concentration of pyruvic acid as conditioning solutions.Etching enamel surfaces with 10% pyruvic acid resulted in the optimal tensile bond strength of the resin to etched enamel surfaces. The use of 10% pyruvic acid did not adversely affect the bond strength of the resin system when compared to enamel surfaces etched with 37% H3PO4for the same time period. Significantly lower tensile bond strengths were recorded on enamel surfaces etched with 20% lactic acid. The rate and depth of etching obtained with 37% H3PO4can be considerably reduced by using 10% pyruvic acid as the conditioning agent.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00950.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SummaryNinety‐nine people who were fitted with partial dentures in 1959 were invited to take part in an investigation 13 years later. A questionnaire was answered by fifty‐eight, which means a frequency of 81% if allowance is made for an explainable loss. Of the sixty‐eight partial dentures in these fifty‐eight patients, twenty‐three were still being used, fourteen patients had had their original partial dentures replaced by new ones and three by a fixed bridge, while seven had been replaced by complete dentures. Twenty‐one were no longer used and had not been replaced. Of the fifty‐four patients who originally had a complete upper denture and a partial lower denture, thirty were still available. Following an invitation to take part in a clinical review, twenty‐seven (90%) co‐operated. Most of the patients were in need of treatment (for caries, periodontitis and/or prosthetic treatment). The periodontal injuries were rarely serious. A correlation was found between good oral hygiene and good res

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00951.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SummaryAn analysis of five proprietary acrylic soft lining materials revealed that they can be classified into two groups. The first of these groups (Soft Oryl and Coe Soft) resemble the tissue conditioners in composition in that their liquid component contains no monomer. A study of their mechanical properties may reveal that these materials should, in fact, be classified as tissue conditioners.The second group (including Palasiv, Virina and Coe Super Soft) were more conventional acrylic materials which differed in the amount of plasticizer and the type of acrylic monomer used in the liquid component and in the nature of the polymer component.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00952.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SummaryAs part of a cineradiographic study of temporomandibular joint movements, the reliability of the apparatus and techniques has been assessed. The areas of concern were the radiographic procedure, tracing apparatus and tracing technique.To assess the accuracy of the radiographic procedure, anatomical and radiographic measurements of mandibular condyles were compared. A range of variation of 0.46–0.8 mm was found, which compared favourably to the only previously published investigation. The use of mechanical devices simulating the fundamentals of mandibular movements suggested that the cineradiographic record showed paths of opening and closing separated more widely than occurredin vivo.The reliability of the tracing apparatus was assessed by calculated misalignments and found to be acceptable.The subjective error in tracing cineradiographic films by a regular observer was investigated by a point location error method. The error was found to be small and within acceptable limit

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00953.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY

摘要:

SummaryA clinical study of the use of root abutments as an aid to the support of complete dentures is presented. This technique offers a realistic alternative for patients who are reluctant to face the loss of their remaining natural teeth and the wearing of complete dentures. The abutments enhance the support and stability of the dentures and appear to slow the rate of alveolar resorption. The clinical procedures are straightforward and can be readily applied in general dental practice.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1976.tb00954.x

出版商:Blackwell Publishing Ltd    

年代:1976

数据来源: WILEY