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Results for “DENTAL MODELS”

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At least 685 records · Page 38Linked to original sources
PubMed2005

Efficacy of a posterior implant support for extra shortened dental arches: a biomechanical model analysis.

The purpose of this study was to test the efficacy of utilizing implants underneath distal free-end denture bases to establish a stable occlusal support for extreme shortened dental arches (ESDA). The authors constructed a two-dimensional finite element model of the ESDA where only lower anterior teeth remain. Posterior occlusal support was provided by a fixed partial denture with an osseointegrated implant (IFPD), fixed cantilever partial denture (CFPD), or a removable partial denture with or without an implant underneath (IRPD and RPD). A dentate mandible model was the control. When muscle vectors simulating clenching force were applied, stress levels on the temporal bone surface area under each configuration were compared, to evaluate the efficacy in establishing the occlusal support. The largest stress increase in temporal bone was found in the ESDA situation followed by the RPD. The least amount of stress increase was found with the IFPD followed by IRPD when the implant was placed in the molar region. The stress increase with IRPD was about 20-45% of the amount with RPD. Our results suggest that IFPD provides most favourable and stable occlusal support, however, IRPD with a single posterior implant also provide stable occlusal support with reducing the stress levels in the temporomandibular joint.

Biomechanical Phenomena↗
PubMed2000

Preliminary evaluation of a new dental implant design in canine models.

Problems with crestal bone resorption and bone adaptation to dental implants in compromised and weak bone present clinical challenges due to insufficient bone volume. Mathematical models have shown that a new, square-thread, dental implant design increases functional surface area and reduces shear loading at the implant interface. The aim of this investigation was to evaluate the ability of bone to grow between the threads of the new implant and its general biocompatibility in a canine model. Test implants were placed in the mandibles of four beagle dogs after posterior partial edentulism. Three months after implantation, the animals received independent fixed partial dentures, were followed for an additional 6 months, and then euthanized for histological analyses. Analyses revealed that bone grew between the threads and closely apposed the new implant design. Histological observations also revealed that the inferior aspect of the test implant threads were apposed by more bone than the coronal aspect, suggesting a biological advantage for the compressive load transfer mechanism of the new implant design. The results of this study revealed that the new implant design became osseointegrated with bone growing between the threads of the device.

Animals↗
PubMed1999

Dental insurance, managed care and traditional practice.

BACKGROUND AND OVERVIEW: The author examined the impact of trends in commercial insurance plans and their managed care products on the traditional fee-for-service solo or partnership model of dental practice. CONCLUSION: In response to rising dental expenditures, employers are passing on more costs of dental insurance to employees, dropping dental benefits altogether and moving from indemnity to managed care plans, mainly preferred provider organizations. These trends are likely to continue, resulting in fewer people with employer-based dental insurance coverage. PRACTICE IMPLICATIONS: These changes in dental insurance coverage are unlikely to challenge the traditional model of dental practice within the next five years, largely because of the growing decline in the supply of dental services and a lack of local market concentration of dental managed care companies.

Dentists↗
PubMed2001

Studies on dental erosion: an in vitro model of root surface erosion.

Most research on dental erosion has focused on erosion in enamel. However, the increasing retention of teeth into old age has increased the potential for root surface erosion. The nature and kinetics of root surface erosion have not yet been adequately explored. The objective of this project was to develop an in vitro model of root surface erosion in order to investigate the polarised light microscopy of controlled erosion and the histology and rate of demineralisation of this process in root cementum/dentine. The results demonstrate a process quite different in outcome from that in enamel erosion. Erosion results in loss of volume of enamel. However, it leaves a root surface softened though with little volume loss so long as the demineralised collagen remains hydrated. The polarised light histology was similar to that seen in root surface caries. The rate of erosive demineralisation of tooth roots by selected acids was investigated, with differing rates of demineralisation similar to that seen in enamel erosion observed. The process of erosion showed evidence of significant diffusion control.

Acetic Acid↗
PubMedDate not supplied

Picenadol in a large multicenter dental pain study.

STUDY OBJECTIVE: To estimate the analgesic dose of picenadol hydrochloride equal to codeine 60 mg in a dental pain model. DESIGN: Randomized, double-blind, parallel, dose-response study. SETTING: Four university-based dental clinics. PATIENTS: Four hundred eight adult patients with moderate or severe pain after extraction of one or more impacted molar teeth plus bone removal. INTERVENTIONS: Patients received orally administered single doses of picenadol 15 and 30 mg, codeine phosphate 30 and 90 mg, or placebo. METHODS: Single oral doses of picenadol 15 and 30 mg, an opioid agonist-antagonist, were compared with codeine 30 and 90 mg and placebo in 408 patients with moderate or severe pain from third molar extraction in a randomized, double-blind, parallel study. Assessments were performed for pain intensity, pain relief, and adverse events for up to 6 hours after drug administration. MAIN RESULTS: Picenadol 30 mg and codeine 90 mg were more effective than placebo based on sum of pain intensity differences, total pain relief, peak pain relief, and duration of analgesia (p < 0.05). Compared with placebo, the frequency of adverse events was highest for patients receiving codeine 90 mg (p < 0.05). No patients discontinued due to adverse events, and all such events resolved spontaneously. CONCLUSIONS: Picenadol 22 mg was estimated to be equianalgesic to codeine 60 mg, and picenadol 30 mg was safe in this dental pain model.

Adult↗
PubMed1997

Effect of masticatory cycles on tooth compression and resultant leakage of amalgam retrofills.

This study was carried out to investigate the effect of changes in tooth structure due to masticatory cycles on amalgam retrofillings performed to different cavity depths. Forty upper maxillary first molars were tested. In the obturated palatal root apical amalgam was inserted to different depths (1.5 and 3 mm). Eight casts were built, each having four sample molars. To block the teeth, the vestibular roots were embedded in resin (palatal root was left free). The eight remaining retrofilled teeth served as controls and were not submitted to occlusal forces. A mechanical device to simulate masticatory cycles subjected the teeth to 500,000 to three million cycles. Leakage was assessed from dye penetration observations. The values of microleakage were analyzed and compared, and strain gauges were used to assess structural modifications to the tooth. The leakage of all retrofilled obturations increased in correlation with the number of masticatory cycles. At three million cycles, root length compression was 0.3 +/- 0.02%. Leakage was significantly less for the deeper cavity preparations at all stages. This in vitro study suggests a significant effect by root compression due to masticatory loads on the leakage of retrofilled amalgam obturations.

Analysis of Variance↗
PubMedDate not supplied

Dental lab technology in the digital age.

The "Information Age" is starting to have an impact on dental technology. Procera, Cerac and several other digital systems are commonly used by many technicians. Other systems are being developed and marketed. Computer Aided Design (CAD) can be used by dental technicians to create precise dental restorations. Solid modeling techniques can provide unique dental applications.

Computer Simulation↗
PubMed1989

A mechanistic study of the electrochemical corrosion of the gamma 2 phase in dental amalgams. II. Introduction of a model.

Electrochemical impedance measurements on conventional dental amalgams at an anodic polarization potential of -250 mV vs. SCE were performed. An initial evaluation was given in part I of this study; in the second part the results are interpreted in terms of a model. The latter, characterized by an equivalent circuit, is a parallel combination of a flat surface and a pore. The selection of appropriate values for the elements of the equivalent circuit leads to a better insight into the corrosion process. Although no simple relationship exists between the circuit elements and the impedance curves, an explanation was found for some typical features of these curves. As an application, the influence of the anodic polarization potential on the impedance curves was studied. Evaluation by means of the model demonstrated the importance of the characteristics of the corrosion products.

Corrosion↗
PubMed2005

A model for clinical credentialing of dental school faculty.

Committed to the premise that the same standards of review for clinical practice may be applied to clinical teaching, The University of Texas Health Science Center Dental Branch at Houston began credentialing clinical faculty in 1997 as part of its quality assurance and risk management program, one of the first dental schools in the country to do so. Credentialing, modeled after health care institutions such as hospitals, is general and procedure-specific involving the review of qualifications such as licensure, training, education, experience, and performance of professional practitioners; measuring those qualifications against pre-established criteria; and granting of "clinical privileges" to clinical faculty to perform or supervise procedures for which they are deemed qualified, based on that review. The development process included the leadership of the Quality Assurance and Risk Management Committee who met with all interested parties, explained the rationale and justification for credentialing, and successfully gained the support of the clinical department chairs, clinical faculty, faculty senate, and the administration of the school in implementing the credentials process. Evaluation of this process indicates that it has been useful in providing a mechanism to address a variety of patient care and clinical education issues such as faculty competency, compliance, and accommodations through a peer review process.

Accreditation↗
PubMed1976

A regression model analysis of longitudinal dental caries data.

Longitudinal data on caries experience were derived from the reexamination and interview of a cohort of 306 subjects with an average follow-up period of 33 years after the baseline examination. Analysis of the data was accomplished by the use of contingency tables utilizing enumeration statistics compared with a multiple regression analysis. The analyses indicated a strong association of caries experience at one point in time with the caries experience of that same person earlier in life. The regression model approach offers adjustment of any given independent variable for the effect of all other independent variables, providing a powerful means of bias reduction. The model is also useful in separating out the specific effect of an independent variable over and above the contribution of other variables. The model used explained 35% of the variability in the DMFS scores recorded. Similar models could be useful adjuncts in the analyses of dental epidemiologic data.

Adolescent↗