摘要:

SummaryIn addition to bone‐bonding bioma‐terials such as calcium phosphate ceramics and Bioglass/glass ceramics, an elastomeric poly(ethylene oxide) poly(butylene terephthalate) (PEO/PBT) segmented block co‐polymer (Polyactive®) was recently introduced. In contrast to ceramic bioma‐terials, Polyactive® is a flexible material. In a previous three‐dimensional finite element analysis study, it was stated that application of a flexible Polyactive® coating simulates the function of the periodontal ligament. The topic of this investigation was to compare the bone‐bonding capacity of Polyactive®‐coated titanium implants with hydroxylapatite (HA) coated implants. The implants were inserted bilaterally in the edentulous part of the mandibular bone of 12 goats. After 3 weeks, the implants were in close contact with the cortical bone, but no cortical bone reaction or remodelling was observed. After 9 weeks, an extensive bone reaction was seen around the HA and Polyactive®‐coated implants and contact was frequently encountered between newly formed bone and the implants. Within the surface of the Polyactive® coating, a considerable amount of calcification was present. After 25 weeks, cortical remodelling was still apparent. A striking finding was the apparent association between osteon formation and calcification within the surface of the Polyactive® layer. Back‐scatter analysis of the non‐decalcified Polyactive® bone interface showed the presence of a calcium phosphate layer in the implant material that apparently formed a continuity with the mineral matrix of bone, suggesting bone‐bonding. In general, it was observed that the bone reactions to HA and Polyactive® were comparable. A swelling of the coating, just beneath the cortical layer (champagne‐cork effect) was often seen. This increase in volume, caused by water uptake, might result in a more intimate initial bone/Polyactive® contact, as comp

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01560.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryToothpastes are commonly used in the treatment of dentine hypersensitivity. One mode of action could be to block patent dentinal tubules with toothpaste ingredients or by abrasion to form a smear layer. Studiesin vitrohave shown that tooth‐paste abrasives have variable affinity for the dentine surface but retention may be limited. This SEM study extended previous work and determined the uptakein vitroof toothpaste ingredients onto the dentine surface and their retention when challenged by washing with water or orange juice. All products were seen to leave variable residues on the surface of etched or unetched dentine specimens, furthermore brush application produced some smearing with closure of previously open tubules. Washing with water and more particularly orange juice removed most residues and orange juice etched the dentine to open previously closed tubules. One product with an artificial silica abrasive was relatively resistant to both water and orange juice washings and in a pilot experiment showed some penetration into tubules not seen with another desensitizing product. These findings suggest that some abrasives may be usefully employed in desensitizing products, but without consideration of erosive factors in the aetiology of dentine hypersensitivity recurrences of the condition will be commo

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01561.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe effect of silanation on the dispersion of quartz and zirconia‐silica fillers by monomers used to formulate composites was studied. Sixteen silane coupling agents and three methods were used, and the amounts of the monomers needed to reach wet and flow point values were determined. The silanes were selected to have a variety of organofunctional and hydrolysable groups. Silanation was done from an ethanol‐water solution of the silanes and by adding the silanes directly to the filler at room temperature (24°C) and at the boiling temperature of the silanes. The amount of silane used was either that required to produce minimum uniform coverage on the fillers or three times the minimum coverage. All silanes and all methods of treatment decreased the flow values for both fillers compared to the unsilanated controls. Generalizations were that the effectiveness of silanation on the dispersion of the filler particles was greater (i) when silanation from ethanol solution was used compared to direct addition; (ii) when three times the minimum uniform coverage was used; (iii) when the silane contained methoxy rather than ethoxy groups; (iv) when the silanes were trialkoxy rather than dialkoxy compounds; (v) when the length and bulkiness of the organic functional group was smaller; and (vi) when the organic functional group was methacrylate rather than acrylic. The strength of composites prepared from one of the monomer systems and quartz silariated with methacryloxypropyltrimethoxysilane was higher than those silanated with acryloxypropyltrimethoxysilane, which supports the use of the wet and flow point values as screening tests for estimating the dispersability of fil

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01562.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryIn six healthy subjects, the integrated electromyographic (IEMG) activity of the right masseter muscle was recorded during 10s of maximum voluntary teeth clenching, without and with manual movements (at a rate of 1.6 Hz, with a force of approximately 3 N) of the bipolar surface electrodes affixed to the cheek. All IEMG recordings were undertaken at discrimination thresholds of 1 μV and 30μV. Electrode movements were the likely source of some distortion (artefact) of the IEMG readings. An increase in the discrimination threshold (30 μV vs. 1 μV) seemed to decrease the artefactual effects of electrode movements, possibly because the movements exerted their major distorting effects on the smaller (low voltages) masseteric motor un

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01563.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe surface texture changes of three kinds of glass‐ionomer cements were compared with various glazed and polished cement surfaces after the initial finishing. Method 1–the glazing agent–was used, and method 2 consisted of four different Shofu Super Snap discs. In method 3 specimens were compressed with a glass plate. The glazed and polished surfaces were used for investigating various properties such as the surface roughness, colour change, gloss, hardness, toothbrush wear, and were also subject to SEM (scanning electron microscope) observation in the laboratory. The period of 48 h after mixing was chosen for the various testing data. The smoothest surface was formed after compression with a glass plate, however, the glazing agent gave the highest gloss surface for glass‐ionomer cement. The lower roughness generally observed was for glazing compared to polishing. The glazed surface is effective as a glass‐ionomer cement re

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01564.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryOcclusal sounds, contact timings and time moments were measured and analysed on 10 subjects onto whom an occlusal interference was created experimentally. A full‐cast double crown was unilaterally set on the upper first molar of each subject, then gradually elevated for 0.06, 0.10, 0.20 and 0.30 mm by inserting a pre‐calibrated metal folio. Occlusal sound was measured with an analyser designed for the purpose. Timings and time moments were analysed with a T‐scan system. All measurements were performed at least 10 times per subject. The results showed that prolonged occlusal sound duration, changes in acoustic signal waveform and increased shift of the centre of effort were observed concomitantly with crown elevation. Differences in these values at 0.06mm as compared with those at baseline were not statistically significant. This could be explained through a physiological compensation by the periodontal ligament. The differences with baseline were statistically significant from 0.10mm ongoing. The distribution of occlusal conacts was determined by the use of a newly developed parameter. Referred to as ‘Tap Score’, the parameter consists of converting contact timings occuring in seven ranges into least‐square‐based weighted scores. Analysis of the tap score disclosed evident imbalance between the crowned and the non‐crowned side starting from 0.10mm elevation, whereby a forward shift of the major contact point was observed on the non‐crowned side. Our study demonstrated that evident changes in gnathosonic and T‐scan parameters are likely to occur at a crown elevation within a 0.06–0.10 mm range. Not only did the results show the analytical capacity of the combined use of occlusal sound analyser and T‐scan, but also they confirmed that a method using simple chairside devices, e.g. T‐scan and Dental Sound Checker, could be helpful in bringing further understanding and information

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01565.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryThe effect of the method of silanation of zirconia‐silica by 3‐methacryloxypropyltrimethoxy‐silane (MAPM) and 3‐acryloxypropyltrimethoxysilane (APM) on the diametral tensile and transverse strength of composites made from these silanated fillers and a urethane dimethacrylate was determined after 0– 108 h of boiling in water. The water sorption of these composites was also measured at times up to 108 h. Silanation with either silane significantly increased the tensile and transverse strengths and decreased water sorption relative to comparable unsilanated controls. Silanation with MAPM from ethanol solution at three times the minimum uniform coverage gave the best overall results, and the tensile strength tests appeared to be most predictive of effectiveness of the silane t

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01566.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryTooth contact in mediotrusion as well as the signs and symptoms of periodontal and mandibular dysfunction were recorded in healthy patients aged between 20 and 31 with Angle class I or II. Non‐functional side contact (NFSC) was found in 94% of the patients, indicating that it is a common phenomenon. In cases of NFSC, the entire range of movement, and not only the final stage of tip‐to‐tip contact on the working side, should be recorded. Slight positive mobility with tooth faceting, as compared to the adjacent and contralateral teeth, was observed in 56 patients. There was no correlation between mediotrusion and mandibular dysfunction. The cumulative effects of NFSC are not well documented, and longitudinal follow‐up studies should be carried out to clarif

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01567.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryTo investigate the effects of the composition and structure on the gelation of tissue conditioners, we measured gelation time with an oscillating rheometer. Also, the plasticizer factor was determined using linear multiple regression equations with the dependent variable of gelation time and the independent variables of molecular weight, molar volume, solubility parameter and viscosity of plasticizers. The results obtained were (i) gelation time decreased as the average particle size of poly‐ethyl‐methacrylate was decreased and its weight average molecular weight increased; (ii) gelation time decreased as ethanol content in the liquid increased. It varied depending on the type of plasticizer; (iii) it was suggested that gelation time was explained by linear multiple regression equations with independent variable of molar volume, solubility parameter and viscosity of plasticizer. In particular, the most influential factor was suggested to be molar vol

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01568.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY

摘要:

SummaryReliability of the intra‐oral method which orientates the occlusal plane to terminate at the upper level of the retromolar pad was studied. Thirty individuals all with natural teeth and 34 complete denture wearers participated in the study. Stone casts were mounted in the S.A.M. 2 articulator by a quick mount face bow transfer. The angle between the occlusal plane and the articulator horizontal plane was measured in both groups. The angle was 9.42°± 4.1° in dentate individuals and 8.53°± 2.8° in complete denture wearers. No statistically significant difference was found between the groups (t=0.72,P>0.05). Therefore, the method can be advocated for a wide clinical use, as it is a simple method and places the artificial occlusal plane very close to the position of the natural plane of oc

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1995.tb01569.x

出版商:Blackwell Publishing Ltd    

年代:1995

数据来源: WILEY