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PubMed2004

Mechanical properties and three-body wear of veneering composites and their matrices.

Fatigue as one of the major factors affecting three-body wear of resin composites is influenced by mechanical properties of the resin matrix. The aim of this in vitro study was to determine three-body wear (ACTA methodology), fracture strength, and Young's modulus of four veneering composites (Artglass old and new formula, Vita Zeta LC Composite, Targis) and one direct restorative composite (Z 100). Furthermore, three-body wear of the pure matrices of the materials was tested. The wear results were compared to Amalgam as reference material. It should be computed whether there exists a correlation between the wear results of resin composite and matrix alone. Wear of the veneering composites was significantly higher than of Z100 (13 microm) and Amalgam (14 microm; p < 0.01, Mann-Whitney U-test). Mean fracture strengths of indirect composites ranged from 127.5 MPa (Targis) to 71.6 MPa (Vita Zeta LC). The elastic moduli of the composites were between 2.9 and 12.8 GPa. The matrix wear rates did not differ significantly. Three-body wear results of complex resin composites are highly influenced by their filler content, filler particle size distribution, kind of filler particles, shape, and their silanization to the matrix. Due to this fact, three-body wear testing is an essential testing method and cannot be replaced by testing single material components.

Composite Resins↗
PubMed2003

Fracture resistance of fiber-reinforced vs. non-fiber-reinforced composite molar crowns.

UNLABELLED: This study compared fracture resistance of fiber-reinforced and non-fiber-reinforced composite molar crowns under simulated oral stress conditions. Three groups of fiber-reinforced composite crowns were constructed using one polyethylene fiber (belleGlass/Connect) and two glass fiber reinforcement systems (Sculpture/FiberKor, Targis/Vectris). The non-fiber-reinforced crowns based on the facing material alone: Sculpture, Targis or belleGlass. Additionally, crowns were made of the non-reinforced composite Artglass. Each group consisted of eight crowns. All crowns were luted to human molars and exposed to thermal cycling and mechanical loading (6000 x 5 degrees C/55 degrees C; 1.2 x 10(6x)50 N; 1.66 Hz). The fracture resistance was measured using a Zwick universal testing machine. RESULTS: The non-reinforced Artglass crowns demonstrated the highest fracture resistance, significantly higher than the resistance shown with belleGlass, belleGlass/Connect or Targis. Artglass showed an extremely wide distribution of values, however. No statistically significant differences were found between the reinforced and non-reinforced composite crowns of Vectris/Targis, FiberKor/Sculpture or Connect/belleGlass although the reinforced crowns showed a tendency towards higher values. The fracture resistance values scattered markedly more for the reinforced crowns, and their lowest fracture values also reached the level of the lowest non-reinforced crowns. The small distribution of fracture values for the non-reinforced crowns indicates that they will be less susceptible for manufacturing faults and more reliable under clinical conditions. CONCLUSIONS: RESULTS of this study suggest that single molar composite crowns (tested in this study) do not benefit from fiber-reinforcement.

Analysis of Variance↗
PubMed2005

In vitro fracture resistance of four-unit fiber-reinforced composite fixed partial dentures.

OBJECTIVES: The aim of this in vitro study was to investigate the influence of glass fiber-reinforcement on the fracture resistance of four-unit composite fixed partial dentures (FPDs) in the posterior region. METHODS: A total of 70 FPDs were fabricated of the composites Sinfony, Vita Zeta and Targis. With each material, 10 FPDs were made without glass fiber-reinforcement and 10 were reinforced with the new glass fiber system EverStick. In addition, 10 FPDs were fabricated of the material combination Targis/Vectris. After thermocycling, all FPDs were loaded until failure in a universal testing machine. The FPDs were then cut and cross-sectional areas were examined by scanning electron microscopy (SEM). RESULTS: The load to fracture of the fiber-reinforced FPDs lay between 615 and 1191 N, which was significantly greater than the values found with unreinforced FPDs (between 178 and 307 N). The highest values were found with the combinations Targis/Vectris (1191 N) and Sinfony/EverStick (1137 N). SEM showed that the FPDs with EverStick reinforcement not only exhibited fracture lines in the fiber-composite interface, but also more often in the area of the fiber-reinforcement than was the case with the FPDs with Vectris reinforcement. The load to fracture was not significantly dependent on fiber quantity or course of fracture. SIGNIFICANCE: It may be concluded that the fracture resistance of four-unit composite FPDs can be significantly raised by glass fiber frameworks (p<0.05). The reinforcement effect of EverStick depended significantly on the composite used (p<0.05).

Composite Resins↗
PubMed2003

Monotonic flexure and fatigue strength of composites for provisional and definitive restorations.

STATEMENT OF PROBLEM: Ordinarily, the mechanical strength of composites is characterized by their flexural strength. Information as to the material's fatigue strength is seldom provided. PURPOSE: The purpose of this study was to compare the flexural strength and the resistance to fatigue loading of composites and an acrylic resin for provisional and definitive restorations. MATERIAL AND METHODS: Artglass, Colombus, and Targis (composites) and Jet, Protemp II, Protemp Garant, and Provipont DC (provisional restorations) were subjected to mechanical tests. Fatigue tests (MPa) (n = 30 specimens/group) were conducted with the rotating-bending cantilever design. Monotonic flexural strength (MPa) (n = 10) was determined in 3-point bending tests. Fatigue resistance was analyzed via the staircase procedure, and flexural strength was examined by use of the 2-parameter Weibull distribution (confidence intervals at 95%). RESULTS: The mean fatigue resistances (S(50)) in MPa +/- SD were: Targis, 62.1 +/- 7.0; Artglass, 58.5 +/- 3.7; Colombus, 54.6 +/- 6.2; Provipont DC, 29.5 +/- 3.2; Protemp II, 23.1 +/- 5.3; Jet, 22.8 +/- 8.3; Protemp Garant, 19.6 +/- 4.6. The flexure strengths (Weibull's S(0)) in MPa and their shape parameters (m) were: Colombus, 145.2 (13.1); Targis, 110.3 (7.8); Artglass, 5.9 (5.4); Jet, 150.9 (17.3); Provipont DC, 97.3 (23.8); Protemp II, 57.9 (6.4); Protemp Garant, 54.2 (12.8). The S(50) of Targis was significantly higher than that of Colombus but not different from Artglass. In flexion, the S(0) of Colombus was significantly higher than that of Artglass and Targis. The S(50) ranged between 40% and 60% of the S(0) for the composites and between 15% and 30% for the provisional restorative materials. CONCLUSIONS: Correlations between monotonic flexure strength and resistance to fatigue loading were weak. Because fatigue tests are considered more pertinent than monotonic tests as to their predictive value, it is concluded that flexure strength data alone may not provide relevant information for long-term clinical performance. The material's resistance to fatigue loading should also be determined.

Acrylic Resins↗
PubMed2001

Bonding of restorative and veneering composite resin to some polymeric composites.

OBJECTIVES: The aim of the study was to determine bond strengths between different fiber-reinforced composites (FRC) and visible light-curing composites (VCR). METHODS: A total of 180 specimens comprising eight types of FRC substrates and four types of VCR substrates were fabricated and divided in 36 different groups. Substrate surfaces were ground with 1200-grit silicon carbide paper before adding a repair composite (RC). The shear bond strength was determined for specimens without the use of an intermediate resin (IMR), for specimens with the IMR and for specimens with the IMR and thermocycling. Surface roughness of the substrate was measured with a profilometer before adding RC on the substrate. RESULTS: The univariate analyses of variance (ANOVA) revealed significant differences (p<0.001) related to the type of the substrate, the IMR and the thermocycling. The highest shear bond strength for FRC substrates was achieved with StickNet/Z-100 combination and for VCR substrates with Sinfony/Sinfony combination. Surface roughness (R(a)) varied from 0.10 microm of Targis VCR to 0.50 microm for Vectris Pontic FRC. SIGNIFICANCE: Surface roughness seemed not to influence shear bond strengths of RC to FRC and VCR substrates. High shear bond strengths were related to specific materials and IMRs used. In some cases materials performed better without the use of the accessory IMR.

Analysis of Variance↗
PubMed2001

Influence of pH and storage time on the sorption and solubility behaviour of three composite resin materials.

OBJECTIVES: The aim of this study was to determine whether pH and time has any influence on the sorption and solubility behaviour of composite resin materials stored in a buffer solution. METHODS: Three hybrid composite restorative resin materials (Spectrum, Z-100 and ArtGlass) with different matrix structure and filler composition were studied. One hundred and twenty specimens of each material were produced according to ISO 4049. The materials were stored in McIlvain's buffer solution at different pH (4, 6 and 8) at 1, 7, 60 and 180 days. pH measurements were carried out before and after completed storage. RESULTS: Time had a significant influence on the sorption and solubility behaviour of the composite resin materials tested. One of the materials Z-100 showed a significant mass increase and/or decrease depending on the pH of the solution. The material Spectrum was significantly influenced by pH, resulting in different sorption depending on the pH of the solution. CONCLUSIONS: Time of storage was important for the sorption and solubility behaviour of the composite resin materials tested. Comparison of solubility for one of the materials showed twice as high values in the present study as previously reported when distilled water was used as storage medium. pH in the solution seems to have an influence on the sorption and solubility behaviour of composite resin materials. The sensitivity of the sorption and solubility behaviour to time and pH of the materials tested seems to be related to the hydrophilicity of the matrix and the chemical composition of the filler.

Absorption↗
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↗
PubMed2002

Marginal accuracy and fracture strength of ceromer/fiber-reinforced composite crowns: effect of variations in preparation design.

STATEMENT OF THE PROBLEM: Targis/Vectris restorations provide excellent esthetics and clinical success; however, the relationship of their marginal accuracy and fracture strength to the tooth preparation design requires further investigation. PURPOSE: The aim of this study was to evaluate the effect of variations in tooth preparation design on the marginal accuracy before and after cementation and on the fracture strength of the ceromer/fiber reinforced composite crown. MATERIAL AND METHODS: Three metal dies with varying total occlusal convergence angles (6 degrees, 10 degrees, 15 degrees) were prepared. A total of 30 (10 for each angle) Targis/Vectris crowns were fabricated. The restorations were evaluated at 48 points on the entire circumferential margin with a stereomicroscope measuring in micrometers for margin adaptation before and after cementation. The specimens then were compressively loaded to failure in a universal testing machine. Marginal adaptation was analyzed with Kruskal-Wallis test and post-hoc Dunnett test (alpha=0.05). The fracture strength was analyzed with analysis of variance and the Scheffe adjustment at the 95% significance level. Fracture surfaces of the crowns were examined with a scanning electron microscope to determine the mode of fracture. RESULTS: The smallest marginal gap was recorded in angled crowns with a 6-degree convergence (47 microm mean). The marginal gap of most (95.6%) of the crowns was within a clinically acceptable level (established as </=100 microm). The mean marginal gap increased significantly after cementation, with the largest increase in the 6 degree group (76 microm mean). The 6-degree angled crowns had a significantly higher fracture strength (1,543 N) than the more convergent crowns (1,366 N) (P<.001). Mean fracture strength of all the crowns was 1,390 N. Scanning electron microscope observation showed that all crowns exhibited a 2-phase fracture pattern: a crack and chipping of the Targis layer followed by adhesive failure. CONCLUSION: Within the limitations of this experimental design, decreasing the axial convergence angle of the ceromer/fiber-reinforced composite crowns diminished their marginal gap and increased their fracture strength.

Analysis of Variance↗
PubMed1991

The effect of glass ionomer cement and composite resin fillings on marginal gingiva.

Glass ionomer cement and composite resin are the most popular restorative materials in operative dentistry today. Earlier studies have shown more crevicular exudate around different types of composite resins than around intact enamel surfaces. The aim of this study was (1) to investigate plaque, retention on and the condition of the gingiva around, 1-year-old, subgingivally located, glass ionomer cement and composite resin fillings, and (2) to compare the initiation of gingival inflammation around these materials with that around enamel during a 14-day period of experimental gingivitis. Plaque index, gingival index, bleeding on probing and crevicular fluid were recorded and compared intra-individually. The amount of plaque and the degree of gingivitis adjacent to the composite fillings were not significantly higher than those for the glass ionomer cement and enamel surfaces in both the cross sectional and the experimental gingivitis study. Composite resin surfaces showed significantly higher crevicular fluid levels than did enamel at all days in the experimental gingivitis study. Glass ionomer cement showed significantly higher values at day-0 and day-7.

Adult↗
PubMed2002

The treatment of localised anterior tooth wear with indirect Artglass restorations at an increased occlusal vertical dimension. Results after two years.

This study evaluated the use of indirect palatal veneers placed at an increased vertical dimension of occlusion in patients with advanced localised anterior tooth wear. A total of 75 indirect Artglass palatal veneers were cemented on 12 patients. Patients were reviewed until the posterior occlusion had re-established and then annually. Preliminary follow up at two years showed minor failures had occurred in 13.3% of cases. These were repaired with direct composite or polishing only. Posterior occlusion was restored after a mean duration of nine months in ten cases. Artglass indirect palatal restorations are an effective short-term treatment of localised anterior tooth wear.

Adolescent↗
PubMedDate not supplied

Fiber-reinforced composite crowns and FPDs: a clinical report.

PURPOSE: This clinical study reports on the results of single molar crowns, three-unit inlay fixed partial dentures (FPD), and complete-coverage FPDs made of the glass-fiber composite system Targis/Vectris with an observation period up to 4.4 years. MATERIALS AND METHODS: In total, 38 restorations were inserted in 19 patients. Of these, 17 were adhesively fixed three-unit inlay FPDs, five were conventionally cemented complete-coverage three-unit FPDs, and 16 were single molar crowns (six adhesively, ten conventionally cemented). The mean observation period was 2.5 +/- 1.0 years. Events like fracture of the framework or veneer, loss of cementation, signs of wear, and outward discoloration were noted and rated according to modified Ryge criteria. RESULTS: During the observation time, neither loss of cementation nor framework fracture were noted. However, six facings (36%) of the inlay FPDs fractured. The number of cases with discoloration or wear increased over time for all types of restorations. The wear culminated in fiber exposure of two molar crowns (24 months) and one inlay FPD (54 months). One of the five complete-coverage FPDs was replaced at the request of the patient (discoloration). The cumulative survival rate after 36 months was estimated to be 82% for molar crowns and 72% for inlay FPDs. CONCLUSION: Fiber-reinforced composite restorations need further improvement of the veneering composites. Because of the increasing wear, discoloration, fractures of the facings, and fiber exposure, fiber-reinforced composites should only be used for provisional restorations.

Adolescent↗
PubMedDate not supplied

Clinical outcome of glass-fiber-reinforced crowns and fixed partial dentures: a three-year retrospective study.

OBJECTIVE: Glass-fiber-reinforced resin composites for the fabrication of esthetic single crowns and fixed partial dentures have been developed recently. However, little data on the clinical outcome of such restorations have been published. The purpose of this retrospective study was to evaluate the clinical outcome of crowns and fixed partial dentures made from the glass-fiber-reinforced resin composite material Targis/Vectris. METHOD AND MATERIALS: Between 1995 and 1997, 39 patients were treated with 67 single crowns and 83 fixed partial dentures. Twenty-five crowns and 28 fixed partial dentures were cemented with temporary cement, while 42 crowns and 55 fixed partial dentures were cemented with either zinc-phosphate cement or glass-ionomer cement. RESULTS: In September 2001, 57 restorations in 17 patients were still in function. The three-year survival rate calculated according to the Kaplan-Meier method was 58.8% for all restorations. However, after this time, it was 37.5% for crowns and 59.9% for fixed partial dentures cemented with temporary cement, and 55.1% for crowns and 67.9% for fixed partial dentures cemented with zinc phosphate or glass ionomer. The differences between the restoration groups were not statistically significant. CONCLUSION: Glass-fiber-reinforced crowns and fixed partial dentures made with the glass-fiber-reinforced resin composite material Targis/Vectris showed a lower survival rate than that published for metal-ceramic crowns and fixed partial dentures. Therefore, the use of this material for the fabrication of single crowns or fixed partial dentures as permanent restorations cannot be recommended.

Adult↗
PubMedDate not supplied

A systematic review of the scientific documentation of fixed partial dentures made from fiber-reinforced polymer to replace missing teeth.

PURPOSE: Many restorative systems have become commercially available that are based on fiber-reinforced polymers (FRP) for production of fixed partial dentures. However, the clinical documentation of their use has not been systematically reviewed and critically appraised. This systematic review aimed to identify the scientific documentation of all commercially available products within this material group. MATERIALS AND METHODS: MEDLINE was searched for all clinical and laboratory studies on FRP, and papers were browsed to identify product names. Moreover, the Internet was searched to find manufacturers of FRP products. Also, several large trade exhibitions were visited to identify products and manufacturers. All papers that included any data from a clinical setting of an identifiable product were critically appraised. Each product was categorized according to the scientific clinical documentation of their intended clinical use. RESULTS: Eleven commercial products were identified. The scientific clinical documentation of these products varied markedly, but was generally poor. No randomized controlled trials have been carried out on FRPs versus, eg, conventional treatments, nor are any long-term cohort studies available. None of the products demonstrate good evidence for usage as a technical solution to permanently replace lost teeth. CONCLUSION: The use of FRP for fixed partial dentures must still be regarded as experimental.

Composite Resins↗
PubMed1991

Fluoride release from glass ionomer cement in vivo and in vitro.

The aims of this study were to investigate in vivo the release of fluoride from three glass ionomer cements (GICs) Vitrebond, Ketac-Fil and ChemFil II into the saliva of preschool children for a 1-year period and also to study in vitro the release-absorption-release of fluoride from the same GICs for 16 weeks. In the first part of the study, glass ionomer restorations were placed in primary teeth in preschool children. Unstimulated saliva was collected and the fluoride in the saliva was measured before placement of the restorations, immediately after, after 3 weeks, after 6 weeks, and after 1 year. In the second part of the study, test specimens of GICs were placed in deionized water and the release of fluoride was measured weekly for 16 weeks. At week 12, samples were exposed to fluoride toothpaste. The concentration of fluoride in saliva was 0.04 ppm before placement of the restorations. After three weeks it had increased to 0.8 ppm and the level remained as high as 0.3 ppm even after 1 year. In the laboratory study the tested glass ionomer cements showed a capacity to absorb fluoride from the fluoride toothpaste and then release it. It is concluded that glass ionomer cement can act as a rechargeable slow release fluoride device.

Child↗