Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “Mastic Resin”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 163 records · Page 9Linked to original sources
PubMed1994

Occlusal wear simulation with the ACTA wear machine.

This paper describes how the clinical conditions in stress bearing areas are thought to be simulated in the ACTA wear machine. The wear types simulated are erosive wear and contact sliding wear in the presence of a third-body medium, consisting of natural food substances. Wear due to surface fatigue may also be studied with the wear machine. Wear rates for a wide range of resin composites, an amalgam and a glass polyalkenoate (ionomer) cement obtained with the ACTA wear machine correlated with an average correlation coefficient of 0.90 with data collected from clinical trials. The results justify the experimental set-up as being one that includes a realistic simulation of the complexity of clinical wear.

Bite Force↗
PubMed2002

Fracture strength after dynamic loading of endodontically treated teeth restored with different post-and-core systems.

STATEMENT OF PROBLEM: Prefabricated metal and ceramic posts can be used with direct or indirect cores as an alternative to the conventional cast post and core. It is unclear how the fracture strength of zirconia posts with composite or ceramic cores and titanium posts with composite cores compares to the fracture strength of gold posts and cores after dynamic loading. PURPOSE: This study compared the fracture strength of endodontically treated, crowned maxillary incisors with limited ferrule length and different post-and-core systems after fatigue loading. MATERIAL AND METHODS: Sixty-four caries-free, human maxillary central incisors were divided into 4 groups. After root canal treatment, Group 1 was restored with titanium posts and composite cores, Group 2 with zirconia posts and composite cores, and Group 3 with zirconia posts and heat-pressed ceramic cores. Teeth restored with cast-on gold posts and cores served as the controls (Group 4). Teeth were prepared with a circumferential shoulder including a 1 to 2 mm ferrule; all posts were cemented with an adhesive resin cement, restored with complete-coverage crowns, and exposed to 1.2 million load cycles (30 N) in a computer-controlled chewing simulator. Simultaneous thermocycling between 5 degrees C and 55 degrees C was applied for 60 seconds with an intermediate pause of 12 seconds. All specimens that did not fracture during dynamic loading were loaded until fracture in a universal testing machine at a crosshead speed of 1.5 mm/min; loads were applied at an angle of 130 degrees at the incisal edge. Fracture loads (N) and modes (repairable or catastrophic) were recorded. The Kruskal-Wallis test was used to compare fracture loads among the 4 test groups. Analyses were conducted both with and without the specimens that failed during the chewing simulation. A Fisher exact test was performed to detect group differences in fracture modes. A significance level of P<.05 was used for all comparisons. RESULTS: The following survival rates were recorded after the chewing simulation: 93.8% (Group 1), 93.8% (Group 2), 100% (Group 3), and 87.5% (Group 4). The median fracture strengths for Groups 1 to 4 were 450 N, 503 N, 521 N, and 408 N, respectively. No significant differences were detected among the groups. The use of zirconia posts resulted in a nonsignificant lower number of catastrophic root fractures. CONCLUSION: Within the limitations of this study, the results suggest that zirconia posts with ceramic cores can be recommended as an alternative to cast posts and cores. If a chairside procedure is preferred, zirconia or titanium posts with composite cores can be used. Clinical trials are required to verify these in vitro results.

Ceramics↗
PubMed1997

Resin composites in dentistry: the monomer systems.

The present review outlines the history of monomers used in resin composites, motivates further development, and highlights recent and ongoing research reported in the field of dental monomer systems. The monomer systems of most present-day resin composites are based on BisGMA, developed some 40 years ago, or derivatives of BisGMA. In the remaining resin composites, urethane monomers or oligomers are used as the basis of the monomer system. The main deficiencies of current resin composites are polymerization shrinkage and insufficient wear resistance under high masticatory forces. Both factors are highly influenced by the monomer system, and considerable efforts are being made around the world to reduce or eliminate these undesirable properties. The use of fluoride-releasing monomer systems, some of which are under investigation, has been suggested to mitigate the negative effects of marginal gaps formed in consequence of polymerization shrinkage. The very crux of the problem has also been approached with the synthesis of potentially low-shrinking/non-shrinking resin composites involving ring opening or cyclopolymerizable monomers. By the use of additives with a supposed chain transfer agent function, monomer systems have been formulated that improve the degree of conversion of methacrylate double bonds and mechanical properties. Many promising monomer systems have been devised, the implementation of which may be expected to improve the longevity of resin composite fillings and expand the indications for resin composites.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1990

[Time-course of changes in alveolar bone surrounding and vascular system of molars of rats fed a high-protein low-calcium diet].

The purpose of this study was to demonstrate changes in alveolar bone surrounding and blood vessels in the molar teeth of rats fed a high-protein low-calcium diet for various periods of time. Five-week-old male Sprague-Dawley rats were used. Control rats were given a normal diet; whereas the experimental rats were fed a high-protein low-calcium diet for 3, 5, 7, 10, 14, 18 or 21 days. Samples were observed by means of light microscopy and scanning electron microscopy, and the following results were obtained. 1. The changes appeared earlier in the dental alveolus than in the diaphysis of the femur. 2. Early changes in the alveolus were observed clearly in the 7-day experimental group. 3. Bone resorption progressed mesio-distally and cervically from spongy bone with the passage of time, and severe osteoporosis was observed in the 18-day experimental group. 4. An enlarged marrow cavity caused by bone resorption was observed, but the height and overall shape of the alveolar bone showed no changes, indicating the continuance of its support function. 5. The architecture of blood vessels in the bone marrow changed its form gradually from 7-day experimental diet and the vessels appeared to have been functioning like a cushion against mastication or physiological force acting on bone. 6. The vessels in the periodontal membrane exhibited characteristic changes in the cervical and apical resins of the membrane as bone resorption proceeded and changes in vessels in the bone marrow also progressed, and the vessels showed a relatively dense distribution there.

Alveolar Bone Loss↗
PubMedDate not supplied

Attritional wear and abrasive surface alterations of composite resin materials in vitro.

OBJECTIVES: A laboratory study was performed with 232 specimens and 72 human enamel, 24 gold, 24 ceramic and 12 composite antagonists in 22 groups to test attritional and abrasive wear behavior of composite materials compared to wear behavior of human enamel. METHODS: Belleglass HP, Concept Inlay/Onlay, Targis and Targis Upgrade 99 composite resin for lab-made restorations was tested as well as Tetric Ceram and FHC Merz light as resins for direct restorations. Natural human enamel specimens served as control. All specimens were subjected to long-term thermo-mechanical loading in a computer-controlled masticator, chemical degradation and toothbrush/toothpaste abrasion. Wear of specimen in occlusal contact area (OCA), contact-free occlusal area and wear of natural enamel cusps as well as antagonists made of gold, ceramic and composite in identical form was measured after 120,000, 240,000, 640,000 and 1200,000 load cycles. A qualitative SEM analysis was performed to support quantitative data. RESULTS: Belleglass HP and Targis Upgrade 99 restorative materials showed wear resistance comparable to human enamel when loaded with enamel cusps. Wear of Targis versus composite and gold antagonists was significantly higher (p<0.0001). Analysis of surface alterations showed hygroscopic expansion in all composite resins during the test. CONCLUSIONS: As a consequence of this study, necessity to further improve physical properties of composites for long lasting restorations was obvious. Beside of attritional wear in OCA, attention must be given to stable filler-matrix interfaces and prevention of water sorption.

Analysis of Variance↗
PubMedDate not supplied

[A splint construction technique for coadjuvant treatment of parafunctions].

In this paper, we introduce a technique of elaboration of soft acrylic's splints as soon as its respective indications. Its main advantage, in addition to his easy and quick making, is the creation of a inner tube between the splint and the occlusal surface that it provides a more even distribution of the pressures exercised by the mastication's forces on the teeth.

Acrylic Resins↗
PubMed1999

Analysis of a restored maxillary second premolar tooth by using three-dimensional finite element method.

In the first part of this study some physical properties of restorative materials, amalgam, glass-ionomer and composite resin were measured experimentally. In the second part a numerical study was carried out, for which the maxillary second premolar tooth was used. The tooth model was restored with composite resin and amalgam on glass-ionomer, which was used as the base material. The stress distribution investigated was the resultant of the stresses which come from the mastication force and those resulting from the contraction and expansion of restorative materials. All calculations were carried out using the finite element method and programs were written using FORTRAN 77. A load of 450 N, at an angle of 45 degrees to the longitudinal axis was applied on the occlusal margin of the tooth. The tooth was assumed isotropic, homogenous, elastic and unsymmetrical. The distribution of compressive, tensile and shear stresses were plotted for the whole tooth structure.

Bicuspid↗
PubMed1998

[Fundamental study on occlusal wear of high-strength resin posterior denture teeth].

The purpose of this study was to evaluate resistance to occlusal wear in high-strength resin posterior teeth (here in after referred to as HS teeth), and to clarify the effects of occlusal adjustment by grinding on the wear resistance of HS teeth. In order to remove the surface layer of HS teeth, sandblasting was substituted for occlusal grinding. A test machine was designed to simulate mastication for impact and sliding under a load of 500 g. The occlusal wear was measured as change of vertical height and volume of the test posterior teeth. The results were as follows: 1. HS teeth exhibited greater resistance to the occlusal wear than resin and porcelain posterior teeth. 2. HS teeth with sandblasting started to wear earlier than without sandblasting, and showed a greater degree of attrition. 3. Once wearing has started, either with or without sandblasting, attrition seemed to increase on the same curvature of wear. 4. Two types of HS teeth showed different wear patterns. These results suggested that it is important to preserve the surface layer of HS teeth, when applied to the denture prosthesis.

Bite Force↗
PubMed2007

Wear of composite resin veneering materials and enamel in a chewing simulator.

OBJECTIVES: The purpose of this in vitro study was to evaluate the wear of six composite resins for the veneering of crowns compared with the wear of human and bovine enamel, tested in a dual-axis chewing simulator. METHODS: Eight specimens of six different composite resins (Targis I+II, Solidex, BelleglassHP, Estenia, Solidex) and of human and bovine enamel were prepared. Steatite ceramic balls served as antagonistic specimens. Specimens were dynamically loaded in a dual-axis chewing simulator with 49 N up to 1,200,000 loading cycles with additional thermal cycling between 5 and 55 degrees C. After 120,000, 240,000, 480,000, 840,000 and 1,200,000 loading cycles, an impression of the specimens' surface and the antagonistic specimen was taken using a polyvinylsiloxane impression material. The substance loss at the surface was measured with computer-aided laser profilometry. Data were analyzed using ANOVA and the Tukey test. RESULTS: The wear of the ultra fine compact filled composite resins Solidex and BelleglassHP was not statistically significantly different from that of human enamel. The other composite resins and bovine enamel showed a wear statistically significantly higher than human enamel. SIGNIFICANCE: Comparing six composite resins for the veneering of crowns, ultra fine compact filled composite resins BelleGlassHP and Solidex showed a wear not significantly different from the wear of human and bovine enamel.

Animals↗
PubMed1997

Comparative wear ranking of dental restorative materials utilizing different wear simulation modes.

The aim of this study was to compare the wear of seven different restorative materials using two different wear simulation modes. This included a non-impact sliding wear test (rotary pin and disc) and an impact-cum-sliding wear test (masticatory simulator). The difference in wear ranking between the two wear tests was compared as well as the correlation of wear to the hardness of the materials. Hardness ranking in the order of decreasing hardness was as follows: Dispersalloy (DA), P50 (P50), Hi-Dense (HD), TPH (TPH), Fuji II LC (FJ), Dyract (DR) and Vitremer (VM). For volumetric wear using the non-impact sliding test, the following ranking in the order of decreasing wear resistance was obtained: DA, TPH, DR, HD, VM, FJ, P50. The results for volumetric wear with impact-cum-sliding wear testing in the order of decreasing wear resistance were: TPH, DR, P50, AR, FJ, VM, HD. Results showed that there is no correlation between hardness and wear resistance. There is also no correlation between impact-cum-sliding wear and non-impact sliding wear. Impact wear should be considered in future two-body wear assessment of materials.

Composite Resins↗
PubMed1999

Wear of composite resin veneering materials in a dual-axis chewing simulator.

The attritional wear of human enamel and four different composite resins for the veneering of crowns was evaluated in a dual-axis chewing simulator over up to 1200000 loading cycles. Enamel showed less wear than the composite resins. However, an ultrafine compact-filled composite resin (Targis) showed a wear not statistically significantly different from that of enamel. The other composite resins showed a statistically significantly higher wear than enamel regardless whether microfine, ultrafine midway-filled or ultrafine compact-filled.

Analysis of Variance↗
PubMed1979

The effect of relining on the accuracy and stability of maxillary complete dentures--an in vitro and in vivo study.

A technique was developed for evaluating in vitro the accuracy or fit of experimental denture bases using a low-viscosity impression material for determining the space between the master die and the processed denture base. These measurements indicated that relining heat-cured maxillary denture bases with autopolymerizing acrylic resin improved their adaptation to the ridges. Interestingly, if no teeth were present in the heat-cured denture base, markedly less distortion occurred after processing. Limited clinical measurements on the stability of maxillary dentures in function showed no statistically significant change in stability after relining, but the trend was toward increased stability with the relined denture.

Acrylic Resins↗
PubMed1993

Wear of ceramic inlays, their enamel antagonists, and luting cements.

The wear of ceramic inlay materials and antagonist enamel cups was measured in vitro. Per group, six MOD inlays were adhesively cemented in extracted molars. Castable glass ceramic, pressed glass ceramic, and feldspathic porcelain were used as inlay materials. A microfilled and a fine hybrid composite served as luting agents. The restorations were exposed to an in vitro wear test that corresponds to approximately 5 years of clinical service. The wear in the occlusal contact area was quantified during and at the end of the test with a three-dimensional scanner. Final wear measurements on the inlays (mean +/- SD) ranged from 21.8 +/- 8.8 microns for pressed glass ceramic to 59.0 +/- 37.9 microns for castable glass ceramic. The mean wear of the enamel antagonists ranged from 74.6 +/- 32.9 microns for pressed glass ceramic to 153.2 +/- 61.5 microns for feldspathic porcelain. The wear of the luting composites at the end of the test ranged from 4.9 +/- 5.1 microns for microfilled to 12.3 +/- 6.3 microns for fine hybrid.

Aluminum Silicates↗