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PubMed2001

[A study on affecting factors on dental care demands by logistic regression model].

OBJECTIVE: To develop probability model for dental visits based on analysis of the factors affecting people's dental services utilization in urban area of Beijing, thus providing some evidence for forecasting further demanded dental care and building the more efficient oral health care delivery system. METHODS: A cross-sectional survey was conducted amnog 1,517 subjects of all age groups in Beijing selected by stratified, clustering, random sampling. The first model of dental care demand--probability model for dental visits was established with logistic regression. RESULTS: Awareness of oral health showed the most important relationship. Different social background and economic factors also had great effects on demand. Higher demand for care were existed among those who suffered from a disease that was painful or resulted in poor oral function. CONCLUSIONS: It is suggested that dental care has different characters from general health service. Utilization of dental service is largely determined by people's awareness, income and insurance system. So oral health education should be extended in order to promote the effective demands and reduce the potential demands. Rational oral health insurance system should be set up to provide some priority to certain people, thus stimulating the supply of dental care and improving the utilization of dental service. Since raising price for care will restrain the low-incomer's basic demand, and it will neither add the profit nor improve people's oral health, the price decision should be considered carefully. At last, oral health care should be emphasized on children and adolescent as priority age groups based on the conclusion from demand model.

Dental Care↗
PubMed1988

Facial and dental arch asymmetries in Class II subdivision malocclusion.

The purpose of this investigation was to determine if any significant differences existed with regard to dental arch and facial asymmetries between persons having malocclusions with well-defined asymmetric characteristics, specifically Angle's Class II subdivision malocclusions, and persons having normal occlusions. Secondarily, it was sought to determine the nature of the differences that contributed to the asymmetric occlusal relationship of buccal segments observed in Class II subdivision malocclusions. The sample consisted of 28 subjects in each of the two groups. All possessed a full complement of permanent teeth including first molars. The average age of subjects in both groups was 17 years. Measurements primarily of a linear nature were obtained from posteroanterior and lateral cephalometric radiographs in addition to dental models. Specific measurements were summed to produce various indices of asymmetry. Variables were analyzed with multivariate discriminant analysis. A significant discrimination between the two groups resulted; variables describing asymmetry of the dentoalveolar region of the mandible appeared to be the primary contributors to the difference obtained. Asymmetry of the maxillary dentoalveolar region appeared to make a secondary contribution.

Adolescent↗
PubMed2005

Analysis of changes in gingival contour from three-dimensional co-ordinate data in subjects with drug-induced gingival overgrowth.

OBJECTIVES: This aim of this study was to develop and assess a technique that could be used to assess accurately the gingival volume changes seen in drug-induced gingival overgrowth by the analysis of data obtained from an entire gingival surface by means of three-dimensional imaging. MATERIAL AND METHODS: Stone dental models of patients before and after gingivectomy procedures were digitized with a laser scanner and then regenerated as computer models constructed from the acquired three-dimensional co-ordinate data. A comparison of superposed "before" and "after" surfaces was undertaken to assess and accurately quantify changes in gingival contour. RESULTS: The mean vertical tissue reduction varied from 1.58 to 2.56 mm in the four study subjects and individual differences are shown. The maximum thickness of removed buccal gingival overgrowth was found to range between 1.20 and 3.40 mm. The volume of tissue removed from each inter-dental papilla ranged from 4.2 to 46.1 mm3 and the mean volume of the papilla removed from each subject+/-SD values was 24.8+/-13.1 mm3. CONCLUSION: This method will measure changes in gingival tissues to within 60 microm in one plane, making it ideal for the assessment of longitudinal changes in gingival contour as seen in the development of gingival overgrowth, its recurrence after surgery or the changes in volume brought about by surgery.

Gingiva↗
PubMed2003

The effects of active infant orthopedics on occlusal relationships in unilateral complete cleft lip and palate.

OBJECTIVE: To evaluate the effects of active infant orthopedic treatment on dental arch relationships and determine the effect on maxillary growth in children born with unilateral complete cleft lip and palate (UCCLP). DESIGN: The GOSLON Yardstick was used to assess dental models taken on patients treated with and without active infant orthopedics. PATIENTS: Two groups of nonsyndromic Caucasian children born with UCCLP (total n = 40), all treated by the same surgeon and ranging from 5 to 10 years of age, were evaluated. INTERVENTIONS: One group had a Latham dentomaxillary alignment (DMA) appliance inserted at 5 to 6 weeks of age, after which a lip-nasal adhesion was performed at an average age of 3.5 months. This was followed by more definitive nasolabial repair at the average age of 5.9 months. Those patients treated without preoperative orthopedics underwent a lip-nasal adhesion at average age 1.5 months followed by nasolabial repair at average age 5.1 months. MAIN OUTCOME MEASURES: Randomized assessments using the GOSLON Yardstick were done independently at two separate times by three different examiners. Differences in GOSLON scores between the active orthopedic group and nonorthopedic group were evaluated by both categorical and continuous statistical analyses. RESULTS: The mean GOSLON score was 3.30 for the orthopedic group and 3.21 for the nonorthopedic group. There was no significant group difference in the modal scores of the two groups. CONCLUSIONS: This study showed that active infant orthopedics does not affect the dental arch relationships in preadolescent children with repaired UCCLP, compared with a similar group treated without orthopedic intervention at this center.

Activator Appliances↗
PubMed2001

Treatment planning for porcelain veneer restoration of crowded teeth by modifying stone models.

UNLABELLED: The three-dimensional result attainable through porcelain veneer restoration of crowded teeth can be preoperatively determined by diagnostically altering stone study models of the patient's dentition. Techniques for diagnostically preparing and waxing the stone dental models are described in this article, along with the corresponding postoperative restorative results of representative cases. CLINICAL SIGNIFICANCE: Patients with malaligned teeth who are not willing or able to undergo straightening of their teeth with orthodontics, nonetheless may be able to attain straight teeth concomitant with the restoration of their teeth with modified porcelain veneer restorations. This article describes a straight forward treatment planning technique for altering study casts preoperatively, to accurately predict and guide the postoperative outcome.

Adult↗
PubMed1995

The use of time study results in a system model for presenting dental care outcome.

The documentation of dental care outcome and dental clinic efficiency is based on variables for the patient's dental health and on resources in time and costs concerning the dental treatment. The aim of this paper was to measure dental clinic activities using a time study method in relation to a model for a system for presenting dental care outcome, and the dental clinic's output and efficiency. For efficiency reporting of dental care related effects, the documentation should be based on rules for input costs related to dental clinic activities, based on valid country-wide criteria for work times of the dental personnel; dental care economics; and current epidemiological indices. Additional use of results from time studies made it possible to adapt the need of resources in dental care, and to obtain essential information concerning the choice of dental team models. For reporting, a dental health related patient group system, based on the patients' dental health and need of dental treatment, should be used. In the proposed model for a system for presenting dental care, knowledge of patients, and of what services the dental personnel can perform was used.

Adolescent↗
PubMed1977

[Epidemiological study on hepatitis morbidity in dental personnel on the model of the Erlangen university dental clinic].

1. The dentist and staff are exposed to nearly double the risk of hepatitis than the population in general. The risk of infection rises with proved contact with hepatitis patients. 2. About 60% of dental personnel suffers subclinical infections. A subclinically infected person is a source of infection for his patients. 3. The chief source of infection is blood contact. In comparisons with the practitioner with mixed dental practice, the surgically active dentist is exposed to three or four times the infection risk. 4. Serological determination of hepatitis antibodies makes it possible to demonstrate subclinical infections. 5. Consistent prophylaxis against infection is required. After proved contact with a hepatitis patient, infection can be prevented by timely treatment with hyperimmune serum.

Dental Staff↗
PubMed2005

[The electrochemical behavior of titanium and dental casting in modelling oral conditions].

The electrochemical behavior of titanium and dental casting alloys in modelling oral conditions With applying dental implants in the oral cavity the direct contact of various metals (titanium and other casting alloys) is unavoidable. Considering the electrolyte characteristic of the saliva, the chances are given that electrochemical processes might occur under such circumstances. The aim of this study was to investigate the electrochemical behavior of titanium and other dental alloys being in direct contact with the oral environment. Nickel-chromium, cobalt-chromium, high palladium content and gold alloys as well as CP grade I titanium cast samples respectively were involved in the study. Test models were made from these metals. As an electrolyte solution (set to pH 4) artificial saliva and 0.9 % NaCl solution were used. The type and the rate of corrosion were assessed with laboratory immersion test and electrochemical polarization method. In case of polarization method a three-electrode measuring-cell was applied. Laboratory exposure tests revealed that titanium resisted corrosion; there was no sign of corrosion at all. The high palladium content alloy and gold alloy behaved similarly. The nickel-chromium and cobalt-chromium alloys showed some signs of corrosion, especially in sites with damaged surface or inhomogeneities on the surface. Results of the laboratory electrochemical experiments correlated with immersion studies graphically illustrated in the paper.

Biocompatible Materials↗
PubMed1983

A need-based model to project national dental expenditures.

A national model on need for dental treatment, as measured by the HANES survey of the National Center for Health Statistics, is described and applied to determine expenditures required to provide necessary dental services under third-party funding of a national dental program. Services have been divided into five components by type of service and age of the population and expenditures are projected for each year, 1980-84. Total expenditures are projected to increase from 18.98 billion dollars in 1980 to 26.42 billion in 1984. Separate projections are also provided for each component and each service. Expenditures derived from this model are compared to direct projections of trends taking place in the current dental care system. Only minor discrepancies in total expenditures are noted but there are large differences for individual services, notably in the areas of prevention and periodontal diseases. Separate comparisons with demand-based projections derived from the experience of the California Dental Service are also presented. Again, the major differences relate to expenditures for individual services, particularly crowns, for which demand expenditures outstripped need by a three-fold margin.

Adolescent↗
PubMed2000

On the heterogeneous structure of thermally cured bis-GMA/TEGDMA resins.

In this paper we report on the morphogenesis of dental resins formed by a thermally initiated radical cross-linking copolymerization of model dental resins. These systems were considered reasonable model simplifications of the actual resins used in commercial filling composites, veneers, etc. Effect of bis-GMA content varying from 0 to 100% on the degree of conversion and morphology of the cured resin was investigated. Dynamic scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), dynamic mechanical thermal analysis (DMTA) and high temperature solvent extraction experiments were performed in order to determine the nature and location of unreacted unsaturations in relation to bis-GMA concentration. The interval of cure temperatures, ranging from 23 to 250 degrees C, may seem irrelevant from the clinical point of view but is instrumental for an understanding of the processes involved. Single glass transition temperature (Tg) found in DMTA experiments showed that the copolymerization process between bis-GMA and TEGDMA is random in nature, however, the overall cure reaction is inhomogeneous and this inhomogeneity is increasing with increasing bis-GMA molar fraction. Heterogeneous character of the cure was reflected into the network morphogenesis characterized by microgellation preceded by cyclization and, following connection of microgels. These cure kinetics resulted in a heterogeneous morphology of the cured resin. Moreover, it was shown that the cure kinetics controls to a great extent the degree of conversion of the reactive vinylidene C=C bonds in a fully cured resin. A decrease in bis-GMA concentration in the resin mixture led to a higher degree of conversion, however, even a neat TEGDMA homopolymer did not exhibit C=C conversion greater than 65-70% under the cure conditions used. Leaching out tests, consisting of an extraction of unreacted monomer from a finely ground cured resin in boiling cyclohexanone at 160 degrees C over a period of 5 d, revealed total weight loss of the order of 3.2-5.6 wt % regardless of the total conversion. No uncured monomer was detected in the extract solution using FTIR spectroscopy, however, the method used is not sensitive to the presence of oligomers. It was concluded that the remaining unreacted double bonds are the inevitable result of the diffusion controlled heterogeneous cure reaction. The low rate of diffusion in the resin beyond its gel point is controlled by high monomer rigidity, low mobility and radius of gyration of the monomers. The unreacted C=C bonds exist in the form of pendant, side groups chemically attached to the network. In addition, a hypothesis has been proposed that for concentrations of rigid bis-GMA monomers above 50 wt %, preferably only one methacrylate group of its molecule has reacted on the time span of the experiment performed and has been incorporated in the cured network. Hence, a substantial part of unsaturation exists in the solid polymer in the form of pendant groups formed by mechanically ineffective bis-GMA monomers. The results are in good qualitative agreement with computer simulations based on the kinetic gelation model.

Journal Article↗
PubMed2001

Maxillary morphology in obstructive sleep apnoea syndrome.

The aim of this case-control study was to test the hypothesis that maxillary morphology differs between obstructive sleep apnoea (OSA) patients and non-snoring, non-apnoeic subjects. Forty randomly selected patients [36 M, 4 F; mean age 49 +/- 2 (SEM) years] with varying degrees of OSA (mean Apnoea/Hypopnoea Index 32 +/- 4/hour) were compared with 21 non-snoring, non-apnoeic control subjects (18 M, 3 F; mean age 40 +/- 2 years). An intra-oral assessment of the occlusion was carried out, particularly for the presence or absence of posterior transverse discrepancies. Maxillary dental arch width was assessed by standardized lateral inter-tooth measurements (inter-canine, inter-premolar, and inter-molar) from dental models. Palatal height and maxillary depth were also measured. The maxillary dental arch was described by a 4th order polynomial equation. The ratios of maxillary to mandibular width (max/mand) and maxillary to facial width (max/facial) were determined from standardized postero-anterior cephalometric radiographs in a subgroup of patients (n = 29) and all controls. Twenty patients (50 per cent) had evidence of posterior transverse discrepancies compared with one control subject (5 per cent; P < 0.01). All patients had significantly reduced inter-canine, inter-premolar, and inter-molar distances (P < 0.05). The maxillary depth was also shorter (P < 0.05), but palatal height was not different. The quadratic coefficient of the polynomial equation was greater in the patients than in the controls (P < 0.05), indicative of greater arch tapering. Patients had smaller maxillary to mandibular and maxillary to facial width ratios (P < 0.01). These results suggest that OSA patients have narrower, more tapered, and shorter maxillary arches than non-snoring, non-apnoeic controls. Further work is required to determine the relevance of these findings in the pathophysiology of OSA.

Adult↗
PubMed2001

Induction and 3D reconstruction of caries-like lesions in an experimental dental plaque biofilm model.

The aim of this study was to examine an in vitro dental plaque model for volumetric assessment and 3D reconstruction of experimentally bacterial induced caries-like lesions. Twenty-three extracted, impacted human molars were coated with a varnish leaving a 3 x 3 mm window on the smooth surface. The teeth were coated with human saliva and Streptococcus sobrinus 6715 adhered onto the enamel via a sucrose dependent mechanism. The coated teeth were incubated for 1, 7, 14 and 28 days. At the end of each incubation period microhardness was measured on three sectioned teeth of each incubation period at the enamel surface and at 450 and 750 microm depth perpendicular to the enamel surface. The enamel surface was investigated by scanning electron microscopy (SEM) prior to embedding and serial sectioning of 12 other teeth. The serial sections were studied with polarization light microscopy to investigate subsurface demineralization. The outlines of the caries-like lesions were then traced consecutively on transparencies, digitized and three-dimensionally reconstructed to demonstrate the expansion of the lesion into enamel for volumetric assessment. Microhardness was significantly reduced on the enamel surface after 7, 14 and 28 days incubation. The SEM investigation showed a surface demineralization with dissolution of the prism cores after 28 days incubation. Polarization light microscopy demonstrated caries-like lesions with an irregular expansion into enamel. The results demonstrate that the described method produces caries-like lesions which can be used for further experimental studies regarding demineralization and remineralization processes.

Biofilms↗
PubMed1996

Photopolymerized multifunctional (meth)acrylates as model polymers for dental applications.

Polymer networks that can serve as model systems for dental applications were prepared by photopolymerizations of 1,1,1-trimethylolpropane triacrylate, 1,1,1-trimethylolpropane trimethacrylate, 1,1,1-trimethylolethane trimethacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, Photomer 2028 and Photomer 3015. The UV polymerizations were initiated by 2,2-dimethoxy-2-phenyl-acetophenone. Volume shrinkage was followed over the course of polymerization using a dilatometric technique. Incident light intensities ranged from 1 mW cm-2 to 20 mW cm-2. The effects of monomer structure on % volume shrinkage, including pendant group size, molecular weight between reactive double bonds, and acrylate versus methacrylate monomers were investigated. In addition, the effect of incident light intensity on % volume shrinkage was studied. Typical volume shrinkage varied from 3.5% to 13.5%. The volume shrinkage decreased with increasing monomer rank and increased pendant group size; the shrinkage for methacrylates was less than that for acrylates. Increased incident light intensity resulted in increased shrinkage rate, but not in statistically significant increases of the volume shrinkage. Conversion was calculated from shrinkage data and compared to data from monomer extraction experiments. Results indicate that although double bond conversion is low, conversion of monomer units is significantly higher.

Biocompatible Materials↗
PubMed2002

Influence of patient, visit, and oral health factors on dental service provision.

OBJECTIVES: Service provision should reflect the oral health of the patient. However, patient and visit factors may influence service patterns and the appropriateness of care delivered. The aim of this study was to examine factors associated with variation in dental services and to assess whether variation by patient and visit characteristics persisted after controlling for oral health status. METHODS: A random sample of Australian dentists was surveyed during 1997-98 (response rate = 60.3%). Private general practitioners (n = 345) provided data on service provision, as well as patient, visit and oral health variables from a log of a typical clinical day (n = 4,115 patients). Multivariate Poisson regression models were run for eight service areas (e.g., diagnostic, preventive, and restorative). RESULTS: Significant effects (P < .05) were observed for oral health factors in all eight models, visit factors in all eight models, patient demographics in four models, dental knowledge/behavior in one model, and area-based socioeconomic status in one model. CONCLUSIONS: After controlling for oral health, visit characteristics persisted as significant predictors of services, with nonemergency visits, insurance, and capital city location associated with more favorable service mix patterns. Higher socioeconomic status areas and payment scale ratings also were associated with a better service pattern in particular service areas. These findings show that a wide range of factors, in addition to oral health, contribute to variation in service provision.

Adolescent↗
PubMed1999

[A preliminary study on dental-manpower forecasting model of Miyun County in Beijing].

OBJECTIVE: To explore the dental-manpower forecasting model of Chinese rural region and provide references for Chinese dental-manpower researches. METHODS: Chose rural Miyun County in Beijing as a sample, according to the need-based and demand-weighted forecasting method, a protocol WHO-CH model and corresponding JWG-6-M package developed by authors were used to calculate the present and future need and demand of dental-manpower in Miyun County. Further predications were also calculated on the effects of four modeling parameters to the demand of dental manpower. RESULTS: The present need and demand of oral care personnel for Miyun were 114.5 and 29.1 respectively. At present, Miyun has 43 oral care providers who can satisfy the demand but not the need. The change of oral health demand had a major effect on the forecast of the manpower. CONCLUSION: Dental-manpower planning should consider the need as a prime factor but must be modified by the demand. It was suggested that corresponding factors of oral care personnel need to be discussed further.

Adolescent↗
PubMed1985

Applying an evaluation model to a dental public health program.

The applicability of an evaluation model applied to an urban dental public health program was assessed. The model required the specification of objectives and focuses on the accomplishment of these objectives and the associated costs. This model is primarily a goal model as contrasted with a system model; thus, the focus was on goal accomplishment. The model was simple to use and provided detailed evaluation information for use by administrators.

Costs and Cost Analysis↗