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At least 703 records · Page 39Linked to original sources
PubMed2006

Dimensional accuracy of a binder jet model produced from computerized tomography data for dental implants.

A full-scale model produced by multislice helical computerized tomography (CT) was made by using the binder jet method and applied for presurgical diagnosis, surgical simulation, and the production of surgical templates for dental implant treatment. In this study, accuracy of the full-scale model with plaster powder was assessed by shifting the binary threshold values. A step phantom was made from bone-equivalent material. When it was placed in water, the CT imaging was performed with a multislice helical CT unit. Three-dimensional (3-D) images were reconstructed by 3-D visualization software. Using 4 different threshold values, full-scale models were produced by a binder jet method with plaster powder. All sides of the full-scale models were directly measured, and their values were compared with that of the step phantom. The mean difference was approximately 0.1 mm in the axial plane when the setting was 0.75 for the threshold. In total, the mean difference was approximately 0.2 mm when the setting was 0.50 for the threshold. It is suggested this full-scale model could be applied for presurgical diagnosis, surgical simulation, and the production of surgical templates in dental implant treatment.

Computer-Aided Design↗
PubMed1996

The development of the Braun Oral-B Ultra Plaque Remover: an in vitro robot study.

PURPOSE: To assess the efficacy of a new brush head design and brushing action using a novel robot system which simulates normal clinical toothbrush use. The system allows developments in toothbrush design to be assessed prior to embarking on expensive and time consuming clinical trials. MATERIALS AND METHODS: Using this system, the efficacy of a new brush head design combined with a modified brushing speed, was compared with the clinically established Braun Oral-B Plaque Remover (D7 handle and EB5 brush head). RESULTS: A combination of a new brush head (EB9) with longer tufts of bristles designed to improve interdental penetration, and an increased frequency of bristle movement (63Hz, 3,800 strokes per minute - D9 handle) was associated with significantly greater removal of artificial plaque. Visual observation of typodonts suggested that this increased efficacy is related to greater removal of plaque from interdental surfaces and occlusal fissures. These results suggest that the D9/EB9 prototype electric toothbrush is suitable for further investigation and clinical evaluation.

Dental Plaque↗
PubMed1991

[Bidimensional measurements of the dental arches using a digitizer].

This method is based on the photographic reproduction of plaster models of dental arches, having previously identified reference points at a canine, molar and inter-incisor level. Subsequent measurement, using a digitizer, of the distances between the above points allows a precise bidimensional measurement to be easily obtained. By selecting plaster models for the different stages of treatment, the method can also be used to monitor changes in the dimensions of the alveolodental arch induced by therapy, or the possible presence of long-term recidivation.

Analog-Digital Conversion↗
PubMed1975

Impact of expanded-duty assistants on cost and productivity in dental care delivery.

Data from an experimental dental program are used to develop a linear programming model of dental care delivery that the authors use to examine the economic implications of introducing expanded-duty dental assistants (EDDA's) in three types of dental practices. The authors examine the changes in productivity and profitability that result from hiring one or more EDDAs and conclude that a dentist in solo practice can more than double his net revenue by hiring one EDDA but will not increase his productivity further by hiring additional EDDAs. Two- and three-dentist groups also can increase revenue by hiring EDDAs, but, beyond a certain point, an inverse relationship exists between the number of auxiliaries hired and net revenue generated.

Cost-Benefit Analysis↗
PubMed1980

Test of a method to determine socially acceptable occlusal conditions.

A method for determining the social acceptability for dental appearance across the full range of occlusal conditions found in a natural population was developed and tested. The strategy used in developing the Social Acceptability Scale of Occlusal Conditions (SASOC) was to present photographs of 100 dental study models to a large sample of high school students (n = 880) and their parents (n = 403) whose responses were measured by a semantic differential instrument. After refinement of the semantic differential instrument scale scores were derived for each study model by computing the mean individual scores. Ranks were assigned to the mean scores. The Pearsonian correlation obtained between parent and student subsamples was 0.95. The reliability and validity of SASOC were assessed. COCSTOC measures of specific occlusal traits for these 100 study models are available. The future task involves the development of a highly reliable regression equation for predicting social acceptability scores from a small number of objective physical measurements.

Adolescent↗
PubMed2005

Towards automated 3D finite element modeling of direct fiber reinforced composite dental bridge.

An automated 3D finite element (FE) modeling procedure for direct fiber reinforced dental bridge is established on the basis of computer tomography (CT) scan data. The model presented herein represents a two-unit anterior cantilever bridge that includes a maxillary right incisor as an abutment and a maxillary left incisor as a cantilever pontic bonded by adhesive and reinforced fibers. The study aims at gathering fundamental knowledge for design optimization of this type of innovative composite dental bridges. To promote the automatic level of numerical analysis and computational design of new dental biomaterials, this report pays particular attention to the mathematical modeling, mesh generation, and validation of numerical models. To assess the numerical accuracy and to validate the model established, a convergence test and experimental verification are also presented.

Biocompatible Materials↗
PubMedDate not supplied

Antibacterial effect of chlorhexidine on bacteria adsorbed onto experimental dental plaque.

The most common method used to examine the antibacterial effect of antiplaque agents is the minimal inhibitory concentration (MIC) method, which is tested on bacteria in suspensions. Examining the antibacterial effect on bacteria adsorbed onto dental surfaces models is not as popular, although it is clear that such models reflect the conditions in the oral cavity far more accurately than the conventional MIC method. The antibacterial effect of chlorhexidine (CHX) on bacteria adsorbed onto experimental dental plaque model was investigated. Hydroxyapatite beads were coated with human saliva. Next, cell-free fructosyltransferase (FTF) and glucosyltransferase (GTF) were adsorbed onto the beads, and sucrose was added to allow the synthesis of polysaccharide by the surface-bound enzymes. Following adsorption of Streptococcus sobrinus to the experimental dental plaque (EDP), the EDP was exposed to CHX at concentrations between 0.008 to 0.0002% at pH values of 5.5, 6.5, and 7.5. After 150 min incubation, growth of the adsorbed bacteria was measured by their incorporation of 3H-uridine or 3H-thymidine. Comparison of bacterial growth on the EDP with that in suspension showed that the surface-bound bacteria were less sensitive to CHX than were the bacteria in suspension. At all tested CHX concentrations, the antibacterial effect was independent of pH. In addition, under our experimental conditions, the use of 3H-uridine as an indicator of bacterial viability proved to be more sensitive than 3H-thymidine. The antibacterial effect of an agent in a model closely mimicking the tooth surface should generate results that are more relevant to the in vivo conditions than are conventional methods, thus bearing significant information concerning clinical applications of CHX.

Adult↗
PubMed1999

Dental fear in children--a proposed model.

Over the past eleven years, we have worked together to treat children who are dentally phobic. This has enabled us to develop an understanding of how children come to be dentally fearful. We have constructed a model of child dental fear which helps us in our work. It is important to acknowledge that fear is a normal phenomenon when any of us are exposed to threat. Helping dentally fearful children appraise or evaluate threat, face their fear and build upon their strengths is the task facing dentists and, occasionally, psychologists. The consequences for children of not doing so are extreme difficulty with accepting and ultimately total avoidance of treatment. Both of these can persist into adulthood. First, we propose to discuss the normality of fear in children, placing dental fear within a developmental context. We will then outline a model for assessing and treating dental fear which identifies five discrete but interrelated factors. Each of the factors and its treatment is illustrated with examples.

Attitude↗
PubMed1990

A social anthropology model to evaluate curricula of dental schools.

The purpose of the research project was to construct a model to evaluate curricula of schools of dentistry following the social anthropology paradigm. The point of departure for the project was practical experience gained in looking for information which could aid better decisions about how to conduct and change a dental curriculum. Information was obtained from the different people involved in the educational project: teachers, students and patients. Qualitative as well as quantitative curriculum information was included. The general questions posed were not only about 'how much', but also 'what, why, who, where and when?' The model used in the project seems to have been of value. It gave a base for considering why things were happening in the way they were, and facilitated a general explanation about how the main purposes of the school were accomplished.

Curriculum↗
PubMed1991

A random effects model for some epidemiological features of dental caries.

We describe a random effects model for caries lesion development and progression based on considering the effects of the pH fluctuations over time in microbial dental plaque as a Wiener process with a single absorptive barrier. The model predicts that the period of greatest risk to developing caries occurs shortly after eruption, but thereafter the longer a surface survives without developing a lesion, the less likely will it be that a lesion will subsequently develop. The model is able to anticipate why the effect of water fluoridation on caries prevalence is most pronounced when caries is diagnosed at cavity level. This model offers one way in which the variability which characterizes the complex ecosystem associated with dental caries may be considered a subject of interest for enhancing our understanding of its pathogenesis and epidemiology.

Absorption↗
PubMed1984

Reliability of an intraoral camera: utility for clinical dentistry and research.

Photographic images can be reliable and efficient sources of data in dentistry. Many variables can be investigated from single exposures. This study was undertaken to test the reliability of an intraoral graphic instrument--the Orthoscan camera. The utility of this instrument in clinical orthodontics has been described, but the research potential has yet to be investigated. Upper and lower dental arches of fifteen patients were photographed intraorally. Alginate impressions of the arches were taken immediately afterward. Identical intertooth distances were located (1) on the intraoral photographs, (2) on the photographs of the dental casts, and (3) on the dental casts themselves. Univariate and multivariate analyses were used to assess measurement error in these replicate measurements. The camera was found to be a highly reliable instrument. The images are flat and free of distortion, with a one-to-one size relationship. The camera is quite suitable for precise scientific investigations, and the data are acceptable for valid interobserver and interpopulation comparisons.

Cephalometry↗