摘要:

SummaryThree dental nurses took part in an investigation of the reproducibility of the EMG silent period. The latency and duration of the silent period after tooth tapping and jaw jerk were found to be rather stable within the same day and between recordings every other day for 10 days. No differences in the SP variables between right and left side were found. Differences in the latency and duration of the silent period between the masseter and anterior temporal muscles during tooth tapping and jaw jerk were registered. The findings suggest functional difference between the two muscles.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00511.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryIt was investigated whether theoretical doubts against the diametral tensile strength test applied to a material such as dental amalgam in the early stage of hardening have practical consequences. The diametral tensile strength values were compared with compressive strengths. The same conclusions may be drawn independent of whether a compressive or a diametral test is used.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00512.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryEven though the temporomandibular joint is loaded in function, it often arthroses under heavy use. The effects of stress to the joint are not well understood. This study utilizes three‐dimensional photo‐elastic stress analysis to visualize the intensity and direction of stresses within the mandibular condyle generated by various occlusal forces.Functional stresses were shown to concentrate in the condylar neck, but were reduced within the condylar head due to its elliptical shape. Stress directions within the condyle were found to be non‐preferential, varying with different mandibular positions. This supports the idea that the condyle is designed to receive light varied forces rather than heavy, cyclical unidirectional f

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00513.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryThe interaction between tooth and amalgam duringin vitrocorrosion of dental amalgams has been studied in this investigation. Extracted teeth have been restored with five commercial amalgams, one of which was γ2‐free and the others contained the γ2‐phase. The restored teeth were immersed in a 1% NaCl solution for 9 months. Post‐corrosion restorations have been examined by optical microscopy, scanning electron microscopy, and X‐ray microanalysis. The results are: (1)γ2‐containing amalgam surfaces were covered with Ca‐Sn‐P‐rich corrosion products of various morphology which occasionally contained relatively low concentrations of Cl and/or Zn; (2) the corrosion products on the γ2‐free amalgam surface indicated relatively high concentrations of Hg in addition to Ca, P, Sn, Cu, and Zn. These results agree with the past observations that corrosion of amalgam restorations is not an isolated process. Rather it may involve reactions of the restoration and the surrounding oral environment including tooth and oral fluids in which interactions of Sn, Zn, Hg

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00514.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryTo determine the onset of subjective fatigue and the subjective endurance of fatigue and pains in the masseter muscle, ten adult male subjects exercised maximal voluntary tooth clenching. Concomitantly, the electrical activity in the masseter muscle was recorded by bipolar surface electrodes and integrated. Onset of subjective fatigue occurred on average 21 s after onset of muscle hyperactivity and the isometric endurance time of the masseter muscle, during which period severe muscle pains were present, was on average 82 s. The electrical muscle activity of the threshold and endurance tests showed a curvilinear configuration (y = a+b logx), and it is suggested that progressive physiological, or peripheral, muscle fatigue accompanied the psychological, or central, endurance of tooth clenching.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00515.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryIt has been suggested that hypersensitivity and awareness of dentures are causes of retching associated with dentures and dental treatment. Oral form recognition (OFR) and oral motor (OM) ability were examined in fifty‐three pairs of retchers and controls. The retchers had all had problems with retching when wearing dentures or during dental procedures. The controls were the same sex as the retchers and were matched with them as closely as possible for age, remaining teeth and edentulous spaces.No difference in OFR and OM ability was found between the paired subjects which might indicate that increased oral awareness contributed to the retchers' symptom

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00516.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryThe purpose of this study was to investigate the properties of composite materials that had been heated to temperatures which may occur during dry polishing. Bulk composite material was submitted to thermal analysis from R.T. to 200°C. Two distinct stages of thermal reaction in this range could be identified. One at approximately 70°C, which could be related to a further initiating of unreacted groups, and one above 100°C, which could be related to the glass transition. The glass transition was also observed microscopically. Hardness measurements were carried out on the warm material at different temperatures as well as on the material being cooled down to R.T. With temperature rise, a continuous increase in hardness and abrasion resistance could be demonstrated. The observed phenomena for bulk material are related to the properties measured on dry polished surfac

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00517.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryFive overdenture wearers with a small number of remaining natural teeth were selected to evaluate the effect of the afferent input from periodontal mechanoreceptors on masseter activity in man. As a control, a full denture wearer was included. The subjects were instructed to chew a piece of gum, and/or tap their teeth. Surface EMG from the bilateral masseter muscles were recorded and analysed.When functional pressure was applied, during chewing, to the abutment teeth as well as to mucosa through the denture base, masseter activities were encouraged. Following application of anaesthesia to the periodontal membrane of the abutments, masseter activities were reduced.The duration of the silent period (SP) appearing in the EMG burst following tooth tapping was significantly increased with root support compared to mucosal support only. With topical anaesthesia of the periodontal tissues, SP duration decreased significantly.In conclusion, it has become apparent that the pressure sensibility of abutment teeth bearing functional pressure under an overdenture base is capable of facilitating masseter activity, as one of the sources of oral sensory input during mastication.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00518.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY

摘要:

SummaryTo acquire more information concerning the changes of the oral functions in shortened dental arches, a cross‐sectional clinical investigation was carried out among 118 subjects. They were classified into six classes, according to the degree and the symmetry of the shortened condition. The method was based on the measuring of variables which were derived from the oral function. The results showed two patterns of change in oral functions: oral functions that change slowly until four occlusal units are left and then change rapidly, and oral functions that change progressively without a sudden change. The preliminary conclusion is that there is sufficient adaptive capacity to maintain adequate oral function in shortened dental arches when at least four occlusal units are left, preferably in a symmetrical positio

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1981.tb00519.x

出版商:Blackwell Publishing Ltd    

年代:1981

数据来源: WILEY