摘要:

In this study we investigated the effect of metal wire bonding to acrylic resin on the fracture resistance of an acrylic denture base material construction. Two different bonding methods were tested, and after measuring the resistance, the surface of the wires were examined by a scanning electron microscope. The effect that the placing of metal strengtheners in different positions in the acrylic resin had on the fracture resistance of the denture base material construction was also clarified. When three different positions of the metal wires in the acrylic resin were compared, the results showed that bonding of metal wire to acrylic resin somewhat enhanced the fracture resistance of test specimens, while the different positions of the wires had no effect on the fracture resistance.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01606.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

This study was designed to examine the effects of three different types of glass polyalkenoate lining cement combined with three different types of bonding resin and varying surface treatments on the seal between the lining cement and the composite resin as used in the so called ‘laminate’ technique. The seal was assessed using a radioisotope and autoradiographic technique.Results showed that all the cements behaved in a manner specific to them. The seal of all systems examined could be improved, or at least, not compromised, by modification of the surface of the cement prior to attachment of the resin. Only one type of intermediate resin gave a reliable seal when applied to an unmodified surface of any of the cements under investigation.It is concluded that all the glass polyalkenoate cements tested behave differently when used beneath composite resin. Recommendations about the laminate restoration technique must be related to the specific combinations of materials u

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01607.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

For several different procedures and material combinations adhesive Class V composite restorations were made under clinical and under laboratory conditions. Marginal discrepancy and gap formation at the floor of the cavity was recorded by way of SEM on replicas. Only weak correlation could be demonstrated between results obtained fromin vivoandin vitroplaced restorations. In general the hydrophobic resinous bonding systems performed better under laboratory conditions while the hydrophillic glass ionomer lining led to a better marginal integrity under clinical circumstances.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01608.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Electromyographic activity of anterior temporal and masseter muscles was measured in 92 young healthy men and women with sound dentitions during rest position, contact in centric occlusion and clench. Male and female mean potentials were similar except in clench, where males had higher electromyographic levels. Mean pooled electromyographic potentials were 1.9 μV (TA) and 1.4 μV (MM) during rest position, 6.5 μV (TA) and 2.8μV (MM) during contact in centric occlusion. Mean maximum voluntary clench potentials were 181.9μV (TA) and 216.2 μV (MM) in men, 161.7 μV (TA) and 156.8 μV (MM) in women. Examined muscles were more asymmetric at low electromyographic activity (rest and centric occlusion) with the temporal muscle less asymmetrical than the masseter. In females temporal muscle activity tended to dominate at every contraction level, while in males masseter activity was stronger in clench, and temporal activity in centric occlusion and in rest p

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01609.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Previous studies of human muscle inhibition during chewing have shown that many factors contribute to the incidence and intensity of this reflex but few studies have been in a physiological context. During the first crushing cycle of brittle foods ipsilateral masseter muscle EMG, mandibular movement and vibration were recorded simultaneously in four healthy dentate subjects. Experiments were repeated before and during anaesthesia of the cheek teeth on the chewing side. The results suggest that vibration seems to be the most important factor in muscle inhibition during food crushing; conversely periodontal sensation, mandibular closing movement and the preload by the muscle at the onset of food fracture play a minor role.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01610.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

For a wide variety of dentine bonding systems the bond strength before and after thermocycling was determined on dentine with and without hydraulic tubular pressure. The importance of the hydrophillic nature of several bonding systems could be demonstrated. The dentine smear layer could not prevent a negative effect of water in the tubulus on hydrophobic systems. Removal of the smear layer had a positive effect on the durability of the bond. When loaded until fracture, some bonding systems resisted adhesive failure.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01611.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The EMG signals from left and right masseter and anterior temporal muscles of 40 healthy subjects were sampled at rest position and through gradually increased clench level to maximum voluntary contraction (MVC) at intercuspal position. A visual sense feedback of masseter muscle potential value was used for the subject to control clench level. The relationship between mean power frequency (MPF) and potential of EMG was investigated by a curvilinear regression of the second order. It was found that the relationship was of the second order logarithmic curve with maximum value of MPF. With the raising of the potential levels of EMG, the MPF increased at the lower clench levels and decreased at higher clench levels. The results indicate that controlling an identical clench level is necessary for using MPF to describe the functional state of masticatory muscles in the clinical situation.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01612.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

A method for the incorporation of chlorhexidine into acrylic resin using monomer together with the pattern of release of chlorhexidine from treated resin into water at 37°C is described. Release from polished and unpolished resin, and from acrylic prepared by short‐curing and dry‐curing processes are investigated.The pattern of release in all cases was of an exponential nature, showing a rapid release within the first 10 days becoming almost constant at a level of 0.4‐1.5 μg cm‐2at about 20 days. Release was still evident at the end of the test period in all cases. Release of chlorhexidine into water from the short‐cure specimens was accompanied by release of monomer, evident from the odour of the test solutions, indicating that polymerization was n

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01613.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

Local muscle fatigue was investigated in the anterior temporal and masseter muscles during sustained isometric contractions. The volunteers’ subjective perception of fatigue or pain was recorded at intervals during the sustained contractions, and this level was then compared to objective measures of fatigue. These objective measures included shift in median frequency of the power spectrum of the surface‐detected EMG signal, and change in signal amplitude.The relationship was investigated while closing on a bite force meter placed between the second premolars and first molars unilaterally, and while simply clenching with the teeth together without the bite force meter.It was found that the subjective perception of fatigue, as measured on a visual analogue scale (VAS), had a nearly linear relationship with time, and that the relationship between the VAS score and median frequency shift was rather closer than the relationship with amplitude cha

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01614.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

The nature and frequency of dental wear facets were studied in a sample of 18‐year‐old Aborigines, 28 males and 31 females, living at Yuendumu in the Northern Territory of Australia. Facet frequencies were scored indirectly using dental models for all permanent teeth, except third molars, and evidence of non‐masticatory tooth grinding in eccentric jaw positions was also recorded. The interplay between attrition and abrasion in an individual over time was assessed by examining facet appearance on serial dental models obtained at approximately yearly intervals from 7 to 25 years of age.Facetting was found to be a very common feature of the Aboriginal dentitions, with frequencies ranging from around 65% for pre‐molars to about 90% for molars. Evidence of extreme mandibular movement was noted in 93% of males and 100% of females. The longitudinal observations indicated that wear facet definition varied over time, apparently due to episodes of tooth grinding superimposed on continually‐acting abrasive influences.These results show that facetting on teeth associated with extreme mandibular positions and, by inference, the related behaviour of tooth grinding or bruxism are very common features in dentitions of Australian Aboriginals living an essentially non‐industrial

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01615.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY