摘要:

SummaryThe development and progression of cervical lesions have not been thoroughly documented. Clinically, two morphologically distinct forms, saucer‐or wedge‐shaped, have been described. In this study, the micromorphology of manifest cervical lesions was documented in six subjects, by SEM replication and microendoscopy. Optoelectronic recordings were made of extreme mandibular lateral excursions. Salivary parameters were evaluated and a detailed case history, including oral hygiene and dietary habits, was taken.Lesions of varying severity could be observed in the same subject. Longitudinal fractures of the enamel were common. The dietary analyses were uneventful and salivary values were normal. No correlation was found between brushing habits and the location and severity of the lesions. The optoelectronic recordings, however, indicated a possible correlation between irregular lateral excursion and the severity and location of the lesions, with a tendency for fewer and less severe lesions on the preferred chewing side. The results have indicated some areas of interest for future studies applying non‐invasive observation me

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01509.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe aim of this study was to compare the effects upon marginal leakage of a number of dentine bonding agents when used with a posterior composite resin, Occlusin, after storage for periods of up to 2 years. The bonding agents used were Gluma, Scotchbond, Topaz and an experimental material. The results were compared with a glass ionomer, Chemfil II. Class V cavities with or without a bevelled cavo‐surface margin were prepared in the buccal surfaces of extracted premolar teeth. Following restoration, the teeth were stored for periods of up to 2 years and then thermally cycled. Marginal leakage was subsequently demonstrated using a radioactive isotope containing45Ca, and an auto‐radiographic technique. Image analysis was used to determine the total amount of linear leakage for each specimen. The results showed that some leakage occurred for all materials at each time interval. The bevelled design of cavity allowed significantly less leakage than the unbevelled cavity. Overall, there was little difference between the various dentine bonding agents. The glass ionomer restorations showed significantly less leakage than the composite resin and dentine bonding agent combinations in unbevelled cavit

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01510.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryAccuracy of fit of denture bases is critical to adequate retention. This study compared the dimensional change of a newer continuous‐injection technique with a standard trial‐pack technique as determined by measuring the posterior palatal border opening. The influence of palate shape and immersion were also assessed.Stone casts were made from master moulds with either a high or flat palate. Denture base adaptation was measured at 5 mm intervals across the entire posterior palatal border. Measurements were made after deflasking, trimming and polishing, and after immersion in room temperature water for l h, 1 day and 1 week. Statistical analysis (P<0.05) showed that where differences occurred between the two techniques, openings were always smaller for the continuous‐injection technique. It was also shown that dimensional changes were always larger for the flat palate compared with the high palate. Dimensional change using the continuous‐injection technique was reduced by immersion in water, while no influence was observed for the trial‐pack technique. It was concluded that the continuous‐injection technique showed smaller dimensional changes compared with the standard trial‐pack technique, and that these changes were influenced by palate shape and immer

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01511.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryIn 10 male and 10 female adults jaw movements and muscle activity were monitored during chewing. Subjects had a Class I occlusion and fluent unrestricted jaw movements; none exhibited signs or symptoms of craniomandibular disorders. Recordings were made on two occasions separated by 2 weeks. Within each recording session the subjects carried out a number of tasks under direction, including eating nuts and gum. The jaw movements were monitored with a Sirognathograph® which had been interfaced to a computer for data logging and analysis.A computer program identified each chewing stroke and after scrutiny a data base was constructed of measurements from a subset of 4447 suitable strokes. Mean values of 10 parameters selected to describe jaw movements during chewing were entered into ananova. This indicated that the major contribution to variance was due to the subject from whom the data was recorded. This intersubject variability is well known, but can its separation from the other contributions to the variation within the data be assessed? To provide an estimate of the spread of data the variance for each parameter was calculated, transformed and these values entered into an analysis of variance.All subject differed significantly in their chewing movements from one another. But 15 of the 20 subjects showed a greater degree of consistency than the other five: they exhibited good inter‐ and intra‐recording reproducibility. The food being eaten made a major contribution to the variability. The timing of the chewing strokes was also more consistent than the dimensions of the chewing enve

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01512.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThisin vitrostudy investigates whether the surface smoothness of a finished composite resin is a function of the time at which it is trimmed. Five materials were studied. Visiodispers® (VIS) is a sintered microfine, the remainder were hybrid formulations: Miradapt® (MIR), Command Ultrafine® (COM) and two experimental formulations –‘EXP (2)’and‘EXP (15)’– with larger filler particles. All except MIR were photoactivated. Samples were placed and cured in holes machined in Perspex rods, ensuring excess of material and moulded to shape with cellulose acetate matrix strip. The strips were removed immediately after light curing and after 5 min in the case of MIR. Sample groups were finished after the following intervals: 10, 15, 30, 45 s, 1, 2, 3, 4, 5min, dry, and after 1 and 7 days in 37°C water. The finishing procedure used plain‐cut tungsten‐carbide burs and coarse, medium and fine finishing discs, which were applied for standardized times, directions and pressures. Surface roughness was assessed visually and with a surface profilling instrument. COM and VIS materials significantly improved in surface finish when the procedure was delayed for 7 days. However, EXP (2), EXP (15) and MIR surface finishes were independent of finishing time. This may result from a rapid attainment of optimum surface hardness, whereas with COM and VIS incomplete curing leads to smearing of resins and filler

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01513.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryA random sample of 1019 elderly home dwelling persons participated in this study. There were 809 dentate respondents, 28.6% of whom wore removable partial dentures. They were examined for coronal and root caries, gingival recession, pocket depth and loss of gingival attachment. The removable partial dentures were also evaluated. Abutment teeth were found to be more likely to have caries and periodontal disease than all other teeth. Using amanovastatistical procedure, the analysis indicated that the partial denture itself, irrespective of any professionally determined problems with the denture, appears to affect coronal and root caries on the teeth of partial denture wearers. Partial dentures judged to need repair or adjustment were related to periodontal status. The data on adverse effects of partial dentures suggest a need for patient education by the dentist and through public health measures, and good oral self care and regular professional recall for people who wear removable partial dentures.

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01514.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe thermal diffusivity has been measured for 10 glass ionomer and resin‐based materials: three conventional (water‐hardened) glass ionomer cements, two silverreinforced glass ionomers, an experimental stainless steel‐reinforced glass ionomer, three visible light‐cured (VLC) glass ionomer‐resin hybrid materials, and a VLC resin‐based product developed for the same clinical uses as the hybrid materials. Cube‐shaped specimens, c. 10 × 10 × 10 mm, initially at room temperature were immersed in mercury surrounded by an ice‐water bath. From the experimental cooling curve a semi‐log plot of relative temperature decrease vs. time yielded a straight line whose slope is proportional to the thermal diffusivity. The values ranged from 1.74–5.16 × 10−3cm2s−1, and all of the materials tested would have adequate insulating properties provided normal clinical thickness levels for lining materials are maintained. It was found that the thermal diffusivities for the three metal‐reinforced glass ionomers, where composition information is avaiable, do not follow a rule of mixtures applied

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01515.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe purpose of this study was to perform longitudinal measurement of forces transmitted from the denture base to retainers of lower distal‐extension removable partial dentures with a conus crown telescopic system. The experimental denture was embedded with a force‐detecting unit which could detect a change in lateral and vertical forces transmitted from denture base to retainers at the same time. Forces were measured during chewing of food on several separate occasions from the insertion of new dentures to about 3 months after. Max.ver (maximal mean value of vertical force) and Max.lat (maximal mean value of lateral force) were calculated from the peak level of all strokes of chewing of food at the minimum of the interocclusal distance.The results are summarized as follows:(i)There were no significant changes of Max.ver and Max.lat;(ii)There were no significant differences of Max.ver between subjects the value of which was about 20 N;(iii)There were significant differences of Max.lat between subjects the value of which was less than 1

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01516.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryThe physical properties and bond strengths of two glass ionomer materials reinforced with silver and amalgam alloy powders were compared with those of a conventional material from the same manufacture as well as two commercially available products. The diametral tensile strength, hardness and bonding strength are improved with the addition of either commercial available silver particles or fabricated high‐copper amalgam alloy powders to the glass. Simple mixture of the metal or alloy powders with the glass ionomer cement seems to be feasible to improve the properties of the regular cement. However, further studies in formulating an optimal composition of metal or alloy, setting characteristics and long‐term clinical evaluation are necessary before proposing uses for this new mater

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01517.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY

摘要:

SummaryDynamic fracture energies and patterns of fracture in extracted human central incisors were determined for groups of intact controls, groups with Vita Dur N® crowns, Vita Hi Ceram® crowns, Dicor® crowns and porcelain veneers. Teeth were struck on their middle labial surfaces by a pendulum impact device.The mean fracture energy for teeth with Dicor crowns was significantly lower than for all other groups (P<0.05). Control tooth crowns fractured obliquely in an apicaldirection. Vita Dur N® and Dicor® crowns, shattered, the underlying tooth usually fracturing in the plane of the impact force. Vita Hi Ceram® crowns chipped at the site of impact and some fractures were located in the roots. Gold crowns remained cemented and fracture occurred at the crown/root junction, or in the root. Porcelain veneers fractured at the site of impact but remained cemented. Dicor® crowns were less fracture resistant than other restoration types tested. Porcelain veneers and full gold crowns stiffened teeth which led to more root fractures than the porcelain

ISSN:0305-182X    

DOI:10.1111/j.1365-2842.1993.tb01518.x

出版商:Blackwell Publishing Ltd    

年代:1993

数据来源: WILEY