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At least 1,117 records · Page 62Linked to original sources
PubMed1989

Effect of finishing on the in vivo wear rate of a posterior composite resin.

A problem with posterior composites is an unacceptable wear level. One factor contributing to inadequate wear resistance may be the way the restoration is surfaced or finished. A clinical study was carried out to determine the influence of finishing on the wear rate of a posterior composite resin. Except for the first 30 days, the resistance to wear was significantly higher for the unfinished group as compared to those that received a conventional finish. The average difference in wear between the two groups was nearly 40 microns.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1997

Comparing the accuracy of reversible hydrocolloid and elastomeric impression materials.

This in vitro investigation evaluated the accuracy of reversible hydrocolloid, vinyl polysiloxane and polyether elastic impression materials used in conjunction with two die stones. The authors made impressions in an experimental environment that approximated clinical conditions in regard to temperature and moisture. Analysis of variance and t-tests were used to compare corresponding measurements on experimental casts made from the various impression materials.

Alginates↗
PubMed2000

Disinfection and communication practices: a survey of U.S. dental laboratories.

BACKGROUND: The need to disinfect impressions is crucial to prevent the transmission of infectious diseases. The authors report the results of a survey of U.S. dental laboratory directors. The survey was designed to determine how well dental laboratory personnel are communicating with dentists regarding the disinfection of impressions, and, in turn, what laboratory technicians are doing to protect themselves against microbial cross-contamination. METHODS: Four hundred dental laboratory directors were selected in a blinded and random manner. To create a geographically representative sample, an equal number of laboratory directors from the East, Midwest and West were interviewed. A survey consisting of 16 open-ended questions was conducted by trained interviewers via 10- to 15-minute telephone interviews. All dental laboratory directors stated that they were thoroughly familiar with their laboratory's disinfection protocol. RESULTS: The survey documented that the majority of impressions were made of polyvinyl (57 percent) or polyether (27 percent) materials. Only 44 percent of the respondents stated that they knew if the impressions they received had been disinfected. Twenty-three percent of the laboratory directors did not know the method of disinfection used, and 47 percent did not know the length of time involved. Forty-five percent of the respondents reported that they receive inadequate instruction in regard to disinfection techniques. No one class of impression materials was found to be more problematic than others by the laboratory directors. CONCLUSIONS: The results indicate a significant and problematic lack of communication between these team members. The responses also suggested that laboratory-perceived problems with impressions were not linked to any particular type of material, but more to the disinfection technique used. PRACTICE IMPLICATIONS: Lack of communication between dentists, staff members and dental laboratory personnel, along with poor training of laboratory personnel in disinfection techniques, may have a direct effect on the prosthetic results achieved in dental practices.

Administrative Personnel↗
PubMed2002

A method to assess the clinical outcome of ridge augmentation procedures.

BACKGROUND: Alveolar ridge augmentation procedures are often needed prior to implant placement or prosthetic rehabilitation. The purpose of this study was to develop a quantitative method to assess the clinical outcome of such procedures. METHODS: Two volumetric methods, based on the volume difference between the pre- and postoperative ridge, were developed. Either a transparent vacuum stent material (method A) or a silicone impression material in a custom acrylic tray (method B) was used to make an impression of the postoperative stone cast. This impression was then filled with polyvinylsiloxane bite registration material (PBRM) and placed on the preoperative cast. The volume of PBRM at the site of the augmented ridge (corresponding to the achieved ridge volume increase, in ml) was measured gravimetrically. Two independent examiners used both methods, in random order, to assess the outcome of 6 diverse clinical cases. Triplicate measurements were made (method precision). Method accuracy was assessed by fabrication of metal castings (known volumes) applied on a preoperative cast to simulate an augmentation procedure. RESULTS: Intra- and inter-examiner reproducibility was high (intraclass correlation coefficients > or =0.84) for both methods. The volumetric measurements obtained by method B showed excellent correlation with the predetermined augmentation volumes (r2 = 0.99; y = 0.94x + 0.12), in contrast to the measurements obtained by method A (r2 = 0.46; y = 0.43x + 1.37). CONCLUSIONS: The developed volumetric method (method B) is both precise and accurate in assessing the outcome of ridge augmentation. This simple, cost-effective, and easy to implement method should be helpful in clinical studies of ridge augmentation procedures.

Alveolar Ridge Augmentation↗
PubMed1989

[Utility of the impression technique with the individual tray for cast crown].

This study was executed at an opportunity for taking the impressions of a full crown abutment tooth by the five different methods with the four different impression materials; the copper ring tray on the abutment method with the polysulfide rubber, the resin ring tray on the abutment method with silicone rubber, the wash technique with silicone rubber, the hydrocolloid impression technique and the hydrocolloid-alginate impression technique. The reproducibility of the preparation margin on the ten stone dies was photographically measured and the following results were obtained. 1. The reproducibility of the preparation margin was affected considerably by the following conditions. 1) The character of the impression materials, 2) the position of the preparation margin in the gingiva sulcus and 3 the undercut degree beneath the preparation margin. 2. The impression technique with the individual ring tray on the abutment showed great utility under any condition of the preparation margin on the abutment. 3. The impression method should be selected clinically according to the condition of the abutment.

Crowns↗
PubMed1990

Cavity design and marginal degradation of the occlusal part of Class-II amalgam restorations.

The effect of variations in the design of class-II cavity preparations on the marginal degradation of amalgam restorations was included as a study aim in a clinical trial. Four hundred and sixty-eight restorations were placed in 210 patients by 7 Scandinavian dentists using 5 different alloys. The marginal degradation was scored on impressions of the restored teeth by means of a six-point ordinal rating scale. The scores were then compared with defined characteristics of the occlusal parts of the initial cavity preparations. Characteristics of the cavity that could be related to the marginal degradation were diverging occlusal cavity walls, occlusal cavity depth, fissures perpendicular to the cavosurface angle, and rough or variable occlusal cavosurface angles. Cavity preparation features not influencing the rate of degradation were the occlusal width, the location of the cavosurface angle on the cusp slope, occlusal cavosurface angles with sectors smaller than 90 degrees, and less than 1 mm enamel remaining between the cavity preparation and another restoration. The association between the different cavity design features and the marginal degradation varied with the different alloys. Superior marginal performance is probably the result of optimal condensation or surface treatment, rather than features of the cavity preparation.

Dental Alloys↗
PubMed1997

Dental erosion associated with soft-drink consumption in young Saudi men.

This study reports on the causative factors of dental erosion in selected high- (n = 19) and low-erosion (n = 19) subgroups of a larger random sample (n = 95) of young male Saudi military inductees. By means of a questionnaire, the role of various possible factors related to oral health in general, and to dental erosion in particular, was assessed for each participant. Clinical examination included recordings of severity of dental erosion and fluorosis, presence of buccal cervical defects and first permanent molar 'cuppings', DMFT and DMFS, visible plaque index, and gingival bleeding index. In addition, bitewing radiographs, study casts, and intraoral color transparencies were obtained for each individual. Logistic regression analysis showed a strong correlation between the presence of dental erosion and a high level of consumption of cola-type soft drinks. Other statistically significant associated factors, although of less predictive strength, were type of cleaning aid and gingival bleeding index. In subgroup comparisons, dental problems (primarily pain), number of buccal cervical defects, and number of missing teeth were significantly greater in the high- than in the low-erosion subgroup.

Adult↗
PubMed1993

Improvement of CAD to produce crown by considering occlusion.

Improvement of the CAD process to design the shape of crown restorations of a 6 die was carried out by including the bite data of the antagonistic tooth in addition to the data measured in the previous paper. Initially, the position adjustment of the crown data with the bite data in the centric occlusion was attempted. After fixation of the crown data to a suitable position, modulation of the occlusal surface by the functionally generated path (FGP) data was carried out. To connect between the end of the crown data and the margin, a parabolic function was used instead of the B-Spline function used in the previous paper. As a result, the data points were connected more smoothly. Thus, CAD data which were composed of the die data, the crown data, and the connecting data were accomplished. They will be used as the basic data to CAM.

Computer-Aided Design↗
PubMed1999

[Ready-made crowns in the deciduous dentition].

The following review of the literature on "prefabricated crowns for deciduous teeth" attempts to highlight the benefits and limitations of this treatment modality. The use of prefabricated crowns is indicated in the following situations: severe destruction of the clinical crown, deep approximal cavities, bilateral approximal cavities, circumferential caries, history of root canal treatment, and need for fixed space retention. Compared to amalgam restorations involving two or more surfaces, prefabricated crowns on deciduous molar teeth gave very high survival rates. They consist of a chromium-nickel-steel alloy and are reported to have an acceptable gingival tolerance profile. In contrast to the Anglo-American countries this treatment modality is quite uncommon in Germany. A probable reason for this reservation could be that many clinicians often fail to see the need for a filling in the deciduous dentition. Besides, many dentists are reluctant to use local anesthesia in children, which is inevitable in preparing and fitting a prefabricated crown. In the United States and UK dentists are less frequently confronted with this problem, as complex treatments are often carried out under nitrous oxide sedation or insufflation anesthesia. Modern filling materials have been introduced which have the potential to narrow the indications for prefabricated stainless steel crowns. Against this background, future studies are necessary to compare the survival rates of prefabricated crowns and modern filling materials.

Child↗