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Effect of fiber-premixed indirect resin composite substructure on fracture resistance of MOD composite inlays adhered with two different adhesive resin cements
Abstract
This study evaluated the effect of a fiber-premixed indirect resin composite (FMC) substructure on the fracture resistance of mesialocclusal-distal (MOD) indirect composite restorations adhered to extracted human upper premolars. The teeth received a standardized MOD cavity preparation, and indirect composite inlays were fabricated with or without using the FMC. Inlays were cemented into the cavity preparations using either Super-Bond C&B or Panavia F2.0. A total of 28 specimens, namely seven specimens for four groups, were thus fabricated. Failure load and failure energy were determined after thermocycling (4-60 degrees C for 5,000 cycles). In terms of failure load, no significant differences were found among the four groups. In terms of failure energy, FMC substructure exerted a significantly favorable effect on Super-Bond C&B-bonded group but a negative one on Panavia F2.0-bonded group. In conclusion, the failure energy of the group using FMC substructure and which was adhered using Super-Bond C&B was significantly higher than the other groups.
... We must not forget that the thickness of the incrustations plays a crucial role, because the light must reach the total of the cementing agent so that it reaches its maximum hardness. From 3 mm thick, hardness is drastically affected cement [47][48][49][50][51]. ...
The composite resin inlays are a low cost alternative which seeks improvements to the direct filling methods meet the challenges of the marginal adaptation, location of proximal contacts, allows us to improve the restoration dental anatomy and overcome the phenomenon of contraction at large sections of material polymerized outside the dental cavity. The objective of this article was to show the use of the composite with indirect technique how an alternative to easy handle and significant clinical results with the structural involvement of molars. The article reports two cases of composite resin inlay onlay in two permanent molars structurally affected, one endodontically treated. The collection of models is performed by the arch alginate impression of the teeth selected, making silicone light casting the prepared tooth and the rest in type III dental stone to obtain a die of work on drawing up the inlay in incremental technique. The cementation process oral cavity is carried out with dual cure resin cement. To control at six months for signs of a leak or marginal jet we used air-dried syringe, explorer and periapical X-Ray. The clinical examination and radiographic analysis revealed a good performance of the restorations in the absence of mismatch or marginal pigmentation. In conclusions the use of the composite inlays in molars with structural involvement with indirect technique is an alternative to easy handle and significant clinical results.
Las incrustaciones en resina compuesta son una alternativa de bajo costo ante los métodos de obturación directos, frente a las dificultades de la adaptación marginal y la ubicación de contactos proximales, porque permiten otorgar una mejor anatomía dental a la restauración y superar el fenómeno de contracción al polimerizar grandes capas de material por fuera de la cavidad dental. El objetivo del presente artículo fue exponer el uso de la resina compuesta bajo técnica indirecta como una alternativa de fácil manipulación y resultados clínicos considerables ante la afectación estructural de molares. Se presentaron dos casos clínicos de incrustaciones con resina compuesta de tipo inlay onlay en dos molares permanentes afectados estructuralmente, uno de ellos fue tratado endodónticamente. Para la obtención de un troquel de trabajo sobre el que se confecciona la incrustación bajo técnica incremental se obtienen modelos al impresionar con alginato la arcada de los dientes seleccionados, se realiza vaciado en silicona liviana del diente preparado y el resto en yeso piedra tipo III. El proceso de cementación en la cavidad bucal se lleva a cabo con cemento resinoso de doble curado. Las incrustaciones fueron sometidas a un control a los seis meses para evaluar los signos de filtración o desadaptación marginal mediante el secado con aire de la jeringa triple, explorador y radiografías periapicales, que mostraron ausencia de desadaptación o pigmentación marginal. Se concluyó que ante la afectación estructural de molares, las incrustaciones con resina compuesta bajo técnica indirecta fueron de fácil manipulación y se obtuvieron satisfactorios resultados clínicos.
The objective of this study was to assess and compare the flexural strength and Vickers hardness of five nanofiller-containing composites (Filtek Supreme XT, Gradia Forte, Luna-Wing, GNH400N, GCUC) against five microhybrid composites (Meta Color Prime Art, Solidex, Estenia C&B, Ceramage, Clearfil Majesty) before and after rotating fatigue test (RFT). For each resin composite, 16 rectangular beam specimens (2 mm×2 mm×25 mm) were prepared and half of which were subjected to 1×10(4) cycles in RFT. Flexural strength was determined using a three-point bending test. Vickers hardness measurements were carried out on specimens which failed after the three-point bending test. When under the influence of rotating fatigue, the flexural strength of all composites was affected by multiple factors. In contrast, rotating fatigue had no significant influence on the Vickers hardness of both microhybrid and nanofiller-containing composites.
It has been suggested that the provision of dental implants can improve the oral function of subjects with severely resorbed mandibles, possibly restoring function to the level experienced by satisfied wearers of conventional complete dentures. Nevertheless, a quantitative comparison has never been made and can be drawn from the literature only with difficulty, since studies differ greatly in methodology. To make such a comparison, we measured bite force and chewing efficiency by using identical methods in subjects with overdentures, complete full dentures, and natural dentitions. Our results indicated that bite forces achieved with overdentures on dental implants were between those achieved with artificial and natural dentitions. Chewing efficiency was significantly greater than that of subjects with full dentures (low mandible), but was still lower than that of subjects with full dentures (high mandible) and overdentures on bare roots. Differences in the height of the mandible revealed significant differences in chewing efficiency between the two full-denture groups. Furthermore, subjects with a shortened dental arch exerted bite forces similar to those of subjects with a complete-natural dentition, but their chewing efficiency was limited due to the reduced occlusal area. For all groups combined, a significant correlation was found between maximum bite force and chewing efficiency. Nearly half of the variation in chewing efficiency was explained by bite force alone.
Clinicians must be aware of the bonding effectiveness of auto- and dual- polymerizing adhesive systems before choosing the material and technique of cementing inlay/onlays to dentin. An inadequate choice may compromise the success of indirect restorations.
This study compared the microtensile bond strength (MTBS) of indirect composite resin bonded to dentin by light-activated, autopolymerizing, and dual-polymerizing adhesive systems.
Occlusal dentin surfaces of 36 human third molars were exposed and flattened. Teeth were assigned to 1 of the following 6 groups (n=6) of adhesive luting systems: 2 dual-polymerizing systems (Scotchbond Multipurpose Plus/Rely X [SBMP] and Prime & Bond NT Dual Cure/Enforce [PBDC]); 1 autopolymerizing system (ED Primer/Panavia F [EDP]); and 3 light-activated systems (control groups) (Adper Single Bond/Rely X [SB], Prime & Bond NT/Enforce [PB], and Clearfil SE Bond/Panavia F [CF]). The restorative materials were applied according to manufacturer's directions. A 2-mm-thick prepolymerized composite resin (Clearfil APX) disc was cemented with the resin cements on the bonded dentin. Teeth were stored in water at 37 degrees C for 24 hours. Afterwards, teeth were sectioned both mesial-distally and buccal-lingually to obtain multiple bonded beam specimens with 0.8 mm(2) of cross-sectional area. Each specimen was tested in tension at a crosshead speed of 0.5 mm/min until failure. Data (MPa) were analyzed by 1-way analysis of variance and the Tukey post hoc test (alpha=.05). Failure patterns of tested specimens were analyzed using scanning electron microscopy.
Mean MTBS values (MPa) for experimental groups were as follows: SBMP, 32.89 +/- 3.26(a); SB, 26.74 +/- 7.45(ab); PB, 26.11 +/- 4.48(ab); CF, 25.30 +/- 6.42(ab); EDP, 16.82 +/- 5.53(bc); PBDC, 11.20 +/- 5.89(c) (P<.001). Groups with similar lowercase letters were not significantly different. Failure pattern of fractured specimens varied according to the polymerization mode.
The autopolymerizing system and one of the dual-polymerizing systems were as effective as the light-activated systems in bonding indirect composite restorations to dentin.
To compare the fracture resistance and failure patterns of endodontically-treated teeth with a progressively reduced number of residual walls restored using resin composites, with or without translucent glass fiber posts.
Ninety extracted human single-rooted maxillary premolars were used. After endodontic treatment, the following groups were created: Group 1 (control group): endodontically-treated single-rooted maxillary premolars with four residual walls; Group 2: three residual walls; Group 3: two residual walls; Group 4: one residual wall, and Group 5: no residual wall. Groups 2-5 were each divided into two subgroups: subgroups "a" were restored with resin composites, while subgroups "b" were restored with translucent glass fiber posts and resin composites. Static fracture resistance tests and statistical analyses (P= 0.05) were performed.
The mean failure loads (N) were 502.4+/-152.5 (Group 1), 416.4+/-122.2 (Group 2a), 423.0+/-103.3 (Group 2b) 422.1+/-138.9 (Group 3a) 513.2+/-121.7 (Group 3b), 488.7+/-153.7 (Group 4a) 573.4+/-169.2 (Group 4b), 856.7+/-112.2 (Group 5a) and 649.5+/-163.5 (Group 5b), respectively. The samples restored with fiber posts exhibited predominantly restorable fractures. The number of residual cavity walls influenced the mechanical resistance of endodontically-treated teeth.
The purpose of the present study was to evaluate the bond strength between a fiber-reinforced composite (FRC) and six luting agents (Panavia F 2.0, Linkmax MC, Chemiace II, Multibond, Super-Bond C&B, and Fuji I). A prosthodontic resin composite material (RC-control) and a luting agent containing no functional monomer (MT) were used as controls. Shear bond strengths between alumina-blasted FRC and the luting agents were determined after 20,000 thermocycles. The FRC showed superior bond strength when compared with the RC-control. Highest bond strengths were achieved when FRC was bonded with Panavia F 2.0, Linkmax MC, Multibond, Super-Bond C&B, and MT, whereas Chemiace II trailed in the list of resin-based luting agents evaluated. Insufficient bonding was obtained with Fuji I. Results of the present study revealed that when fabricating restorations, the clinician should select an appropriate combination of resin composite material and luting agent so as to ensure the longevity of restorations.
The purpose of this study was to examine changes in translucency and color of particulate filler composite resins that can be fabricated into metal-free crowns.
Eight types of materials were used in this study. The particulate filler composite resins were represented by Artglass, BelleGlass, Estenia, Gradia, and Targis. Herculite XRV and Solidex were the conventional composite resins for crowns and fixed partial denture facings, and Empress was the ceramic material. Disks with a thickness of 1.0 mm were fabricated from each material and subjected to an accelerated test by immersion in 60 degrees C distilled water for up to 8 weeks. Color measurements were made before and after water immersion. Changes in translucency were evaluated by determining the contrast ratio, and changes in color were evaluated by determining color difference.
After water immersion, Targis and Solidex demonstrated a significant increase in contrast ratio (6% to 7%) and a decrease in translucency. A color difference of more than 2.0, a visually perceptible value, was found for Targis, Gradia, and Solidex. However, the maximum color difference for these was 3.0, a value that would be considered clinically acceptable.
Within the limitations of this study, the particulate filler composite resins were stable in both translucency and color.
Micro-tensile bond strength (microTBS) evaluation and fractographic analysis were used to compare four resin cement systems (AC: All-Bond 2/Choice; RX: Single Bond/RelyX ARC; SB: Super-Bond C & B; and PF: Panavia F) in indirect composite/dentin adhesive joints.
Flat dentin surfaces were created on extracted human third molars. The resin cements were used according to the manufacturers' instructions for bonding silanized composite overlays to deep coronal dentin. 0.9x0.9 composite-dentin beams prepared from the luted specimens were stressed to failure in tension. Dentin sides of all fractured specimens were examined by scanning electron microscopy (SEM) to examine the failure modes. In group PF, morphologic features that could not be resolved at the SEM level were further validated by transmission electron microscopy (TEM) examination of the SEM specimens.
Statistical analyses revealed significant difference (p<0.05) among microTBS and failure modes in the resin cement groups. The two groups (AC and RX) with highest microTBS failed predominantly along the composite overlay/cement interface. Cohesive failure in resin cement was primarily observed in group SB that exhibited intermediate microTBS values. In group PF with the lowest microTBS, failure occurred mostly along the dentin surface. Globular resin agglomerates seen by SEM on PF-treated dentin were distinguished from silica fillers by TEM.
The bond between the processed composite and the luting resin cement was the weak link in indirect composite restorations cemented with AC or RX. Super-Bond C&B exhibited intermediate tensile strength and Panavia F is less reliable when used in conjunction with a self-etching primer for bonding indirect restorations to dentin.
Indirect composite restoratives have been improved in their wear resistance and physical properties. Several new indirect composites claim to be successfully used for full coverage crowns, but there is limited information for wear values of these new indirect composites.
The purpose of this study was to evaluate the wear characteristics of 7 indirect composite restoratives and to compare them with a type III gold alloy by means of an in vitro wear test.
Seven indirect composites (2 photopolymerized and 5 photo/heat-polymerized types) and a type III gold alloy (control) were used. Cylindrical Class I cavities (4-mm diameter and 3-mm depth) were prepared in occlusally flattened extracted human molars. Inlays with respective materials were fabricated on duplicated stone casts according to the manufacturers' instructions. Three types of in vitro wear tests were completed by use of the University of Alabama wear simulator. The wear tests included generalized wear as simulation of the wear during mastication, localized wear as simulation of attrition by occlusal contact, and antagonistic enamel wear, which simulated the wear of enamel created by direct contact with the restorative materials. Seven specimens were tested for each material and wear mode, and the wear depths were measured on profilometric tracings with a 2-dimensional profilometer with 1-microm accuracy. All data were analyzed by 1-way analysis of variance, and multiple comparisons were performed with Fisher's test, for which the significant level was set at.05.
The gold alloy control exhibited a very small amount of wear in both generalized wear (0.2 +/- 0.1 microm) and localized wear (13.8 +/- 5.0 microm) as compared with all composite specimens. The antagonistic enamel wear of gold alloy was similar with the value of Sculpture. The material group, which was post polymerized or post heat-treated, included BelleGlass, Sculpture, Estenia, and Cristobal+ and showed small values ranging from 1.6 to 2.2 microm in the generalized wear. For the localized wear, Estenia exhibited the minimum value (12.8 +/- 4.9 microm) that was statistically the same as the value of the gold alloy control. However, Estenia exhibited the greatest antagonistic enamel wear value (66.0 +/- 14.0 microm) of all materials tested in this study. It was statistically significant with other materials (P</=.05).
Within the limitations of this study, it was concluded that some indirect composite restoratives have similar wear resistance to the type III gold alloy tested. Antagonistic enamel was abraded more by highly filled composite materials.
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.
The aim of the current study was to compare the bond strength of an experimental bonding system with commercial bonding systems.
An aqueous solution of 10% ascorbic acid and 5% ferric chloride was prepared as an experimental conditioner (Exp). The flattened human dentin surfaces were conditioned with phosphoric acid, NaOCl, and Exp. They were bonded to a stainless steel rod with 4-META/MMA-TBB resin. Super-Bond C&B (10-3), Panavia Fluoro Cement (Panavia), Panavia Fluoro Cement with AD gel (AD/Panavia), and All-Bond 2 system (All-Bond 2) were also used. After immersion in water for 24 h, half of the specimens of each group were tested for tensile bond strength, and the remaining specimen groups were subjected to 10,000 cycles of thermo-cycling prior to tensile testing. All of the data were analysed by ANOVA and a post hoc test. In addition, two thermo-cycled specimens (10-3/10,000, Exp/10,000) were prepared for photomicrography.
The bond strengths of Exp and AD/Panavia groups showed no decrease after 10,000 thermo-cycles, although those of 10-3, Panavia, and All-Bond groups decreased significantly after thermo-cycling. SEM micrographs exhibited that cracks and voids can be observed in the 10-3/10,000 specimen at the interface of the adhesive resin and the hybrid layer, although neither a hybrid layer nor cracks can be seen in the Exp/10,000 specimen.
Comparison of the tensile bond strengths for all adhesive resins revealed that the novel dentin bond system with experimental conditioner and Panavia Fluoro Cement with AD gel exhibited the most durable bonding after thermo-cycling.
The assessment of bite forces on healthy single tooth appears essential for a correct quantification of the actual impact of single implant oral rehabilitations. In the present study, a new single tooth strain-gauge bite transducer was used in 52 healthy young adults (36 men, 16 women) with a complete permanent dentition. The influences of tooth position along the dental arch, of side, and of sex, on maximum bite force were assessed by an ANOVA. No significant left-right differences were found. On average, in both sexes the lowest bite force was recorded on the incisors (40-48% of maximum single tooth bite force), the largest force was recorded on the first molar. Bite forces were larger in men than in women (P < 0.002), and increased monotonically along the arch until the first or second permanent molar (P < 0.0001). The present data can be used as reference values for the comparison of dental forces in patients.
The improved mechanical properties of contemporary composites have resulted in their extensive use for the restoration of posterior teeth. However, the influence of fiber reinforcement, cementation technique, and physical stress on the fracture resistance of metal-free crowns is unknown.
This in vitro study evaluated the effect of fiber reinforcement, physical stress, and cementation methods on the fracture resistance of posterior metal-free Sinfony crowns.
Ninety-six extracted human third molars received a standardized tooth preparation: 0.5-mm chamfer preparation and occlusal reduction of 1.3 to 1.5 mm. Sinfony (nonreinforced crowns, n=48) and Sinfony-Vectris (reinforced crowns, n=48) crowns restoring original tooth contour were prepared. Twenty-four specimens of each crown type were cemented, using either glass ionomer cement (GIC) or resin cement. Thirty-two crowns (one third) were stored in humidity for 48 hours. Another third was exposed to 10,000 thermal cycles (TC) between 5 degrees C and 55 degrees C. The remaining third was treated with thermal cycling and mechanical loading (TCML), consisting of 1.2 million axial loads of 50 N. The artificial crowns were then vertically loaded with a steel sphere until failure occurred. Significant differences in fracture resistance (N) between experimental groups were assessed by nonparametric Mann-Whitney U-test (alpha=.05).
Fifty percent of the Sinfony and Sinfony-Vectris crowns cemented with glass ionomer cement loosened after thermal cycling. Thermal cycling resulted in a significant reduction in the mean fracture resistance for Sinfony crowns cemented with GIC, from 2037 N to 1282 N (P=.004). Additional fatigue produced no further effects. Fiber reinforcement significantly increased fracture resistance, from 1555 N to 2326 N (P=.001). The minimal fracture resistance was above 600 N for all combinations of material, cement and loading.
Fracture resistance of metal-free Sinfony crowns was significantly increased by fiber reinforcement. Adhesive cementation may be recommended to avoid cementation failure.
The aim of this study was to evaluate the effect of ageing in distilled water on the hardness and compressive strength of a direct composite resin Z100, a feldspatic porcelain (Noritake) and three indirect composites (Artglass, Solidex and Targis). For the Vickers hardness tests, five disk-shaped specimens (2 x 4 mm) of each material were prepared according to the manufacturers' instructions. The hardness tests were conducted using a Vickers diamond indentor. Compressive strength measurements were recorded on cylindrical specimens with a diameter of 6 mm and a length of 12 mm. The compression tests were carried out with a constant cross-head speed of 0.5 mm min(-1) on a mechanical test machine. For each material, 10 specimens were tested after 7 days of dry storage at 37 +/- 1 degrees C and 10 specimens were tested after water storage at 37 +/- 1 degrees C for 180 days. Noritake porcelain specimens showed higher hardness values than the composites. Among the composite materials, Z100 promoted the highest VHN values, regardless of the ageing periods. The results showed that Solidex and Z100 had the highest compressive strength values. Ageing in water reduced the hardness for all composites, but had no long-term effect on the compressive strength.
The effects of the filler composition on physical and mechanical properties of microfilled composites was investigated by measuring water absorption, solubility, compressive, flexural, and impact strength. A series of experimental composites, consisting of UDMA/TEGDMA comonomer matrix and prepolymerized fillers, was fabricated. The prepolymerized fillers were composed of hydrophobic colloidal silica and two monomers in varying ratios, trimethylolpropanetrimethacrylate (TMPT), and polyesterdiacrylate (PEDA). TMPT/PEDA ratios were 100:0, 64:36, 46:54, 18:82, and 0:100%. There were no significant differences in water sorption and solubility, regardless of the amount of PEDA monomer. Young's modulus and modulus of resilience increased with decreasing PEDA ratio. Fracture energy exhibited drastic changes (30.1 x 10(-5) J to 93.4 x 10(-5) J). The highest value of flexural strength (96.0 +/- 3.5 MPa) was obtained when the TMPT-PEDA filler was 46:54. The impact strengths of composites fabricated with TMPT-PEDA filler of 46:54 (11.2 +/- 1.4 kJ/m(2)), 18:82 (10.6 +/- 3.2 kJ/m(2)), and 0:100 (13.1 +/- 3.8 kJ/m(2)) were significantly higher than those with 100:0 (6.0 +/- 1.8 kJ/m(2)) or 64:36 (7.1 +/- 2.4 kJ/m(2)). Based upon the results, it was concluded that the mechanical properties of microfilled composites were improved by the modification of prepolymerized filler composition.
To evaluate the micro-tensile bonding strength (muTBS) of three luting resins to human regional dentin.
Dentin disks from non-carious third molars were prepared from different regions (s, superficial dentin; d, deep dentin; c, cervical dentin), and divided into groups based on anatomical locations and luting resins (Super-Bond C&B: SB; Panavia F 2.0: PF; RelyX Unicem: RU): SB-s, SB-d, SB-c; PF-s, PF-d, PF-c; RU-s, RU-d, RU-c. Luting resins were used according to the manufacturers' instructions, to bond 1-mm-diameter PMMA or composite rods to the exposed dentin specimens under a load of 7.5 N, in the self-curing mode. After storage for 1 or 3 days, muTBS was tested at a cross-head speed of 1mm/min. Data were analyzed with ANOVA and Fisher's PLSD test. The bonding interface and fractography analyses were performed with SEM and TEM.
ANOVA results showed that muTBS to superficial dentin was significantly higher than to deep or cervical dentin for all three luting resins. SB-s and PF-s, with the highest muTBS, failed primarily cohesively in luting resin. muTBS of SB-d and SB-c were significantly higher than those of PF and RU. RU, with the lowest regional muTBS, failed mostly within demineralized dentin. SEM and TEM showed that adhesive failures in SB and PF occurred at the top of the hybrid layer (HL), but no obvious HL was observed in RU.
Luting resins with different chemical formulations and applications yield significantly different bond strengths to different regions in human dentin.
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.
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).
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.
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).
Efficacy of the usage of an experimental fiber-reinforced composite (FRC) on mechanical properties of an indirect composite was investigated by means of three-point bending and Charpy impact tests. Bond strength between the FRC and the indirect composite was also evaluated by tensile testing. The FRC consisted of a matrix resin with 25% silanized milled glass fiber (11-microm diameter, 150-microm length) and 5% colloidal silica. The values of strain of proportional limit, total strain, and fracture energy of the FRC during the bending test (1.2%, 10.4%, and 41.6 x 10(-3) J) were significantly higher than those of the indirect composite (0.1%, 2.5%, and 11.9 x 10(-3) J). The impact strengths of the 1-mm specimens with FRC ranged from 15.2 to 15.9 kJ/m(2), and were significantly higher than that of the control (3.1 kJ/m(2)). The 2-mm specimens showed significant difference from the control when the FRC thickness was equal or greater than 0.5 mm. The bond strength after the thermocycling was 15.2 MPa, and all of the specimens exhibited cohesive fracture inside the indirect composite. Based upon the results, it was concluded that the FRC tested in this study improved toughness and impact resistance of the indirect composite. The interfacial bonding between the FRC and the indirect composite was strong enough to prevent delamination.
The aim of this study was to evaluate the clinical performance of posterior, metal-free polymer crowns with and without a glass-fiber framework, in comparison to metal-ceramic crowns.
After randomisation, 80 single crowns, manufactured from a newly designed polymer composite, were set in posterior teeth. Half of these received a glass-fiber framework, while half were prepared without any framework stabilisation. All polymer crowns were adhesively luted with resin cement. As the control group, 40 conventional metal-ceramic crowns were inserted with hybrid cement. Documentation included failures and other complications, as well as gingival/plaque status and aesthetic performance.
During the 12-month observation period, eight polymer crowns and three metal-ceramic crowns showed clinically relevant complications. The most frequent complications were root canal treatments (n=4) and decementation (n=4) of the crowns. A total of two crowns (one polymer crown with fiber network and one crown of the control group) had to be replaced. After 12 months, polymer crowns with glass-fiber framework exhibited significantly higher plaque accumulation (p=0.005) and gingival index (p=0.04) than metal-ceramic crowns, while no significant differences could be demonstrated for polymer crowns without fiber reinforcement. Postoperative sensibility and aesthetic performance did not differ significantly between the groups.
Within a 12-month observation period, posterior polymer crowns with and without glass-fiber framework demonstrated acceptable stability and aesthetic performance. Polymer crowns with fiber framework showed significant higher plaque accumulation and gingival index than metal-ceramic crowns.
In this study, the effect on the fracture load of inlay-retained composite fixed partial dentures (FPDs) caused by reinforcing them with fiber-reinforced composite (FRC) in different positions was examined. Experimental FPDs were fabricated using Estenia/EG Fiber (Kuraray Medical). Pontic reinforcement was then performed in one of the following three ways: reinforced the central area in a single line or in double straight lines, or reinforced the bottom in a curved line. The finding was that, when the area ranging from the connector to the bottom of the pontic was reinforced with FRC in a curved line, the fracture load of the FPDs tended to become higher. In addition, the FPDs fractured mainly at the veneering composite of the connector area. Based on the results of this study, it was concluded that reinforcement using FRC is effective, and that the veneering composite in the connector area needs to have sufficient strength to prevent the fractures.
To evaluate the interfacial characteristics of five adhesive resin luting agents with dentine including tensile bond strength, failure mode, extent of demineralisation, morphological changes and hybrid layer formation.
The products tested were Bistite II DC (BDC), C&B Super-Bond (CBM), M-Bond (MBD), Panavia-F (PAF) and Rely-X Unicem (RXU). For tensile bond strength measurements (TBS), metallic rods were bonded to standardised dentine surface areas (n=10), thermal-cycled (3000x 5-55 degrees C, 4 cycles/min) and debonded at 1mm/min crosshead speed. The failure mode was examined on dentine surfaces by LV-SEM (n=10), whereas the thickness of the hybrid layer by HV-SEM (n=4). FT-IR microscopy (n=4) and ESEM (n=4) were used to assess the extent of demineralisation and the morphological changes induced on dentine by the conditioning and priming treatments.
TBS (MPa) values were BDC (13.01), MBD (9.19) and PAF (7.07) significantly different from CBM (4.79) and RXU (4.47). The percentage of debonded dentine area covered with resin showed the highest values in BDC (47.80) and MBD (38.12) significantly different from CBM (17.20), PAF (16.47), and RXU (16.50). The extent of demineralisation for CBM was 100%. No statistical differences were found among BDC (60.86%), MBD (60.22%) and PAF (51.99%). RUX (45.03%) showed the lowest value. CBM induced the most pronounced tubule funneling and intertubular dissolution, followed by PAF, BDC and MDB. RXU partially removed the smear layer without opening tubule orifices. The thickest hybrid layer was found in CBM (4.17microm) followed by MBD (2.39microm). No statistically significant differences were found between PAF (0.95microm) and BDC (1.12microm), whereas RXU showed no detectable hybrid layer.
Significant differences were found in the interfacial properties among the materials tested, that may lead to differences in their clinical performance.
To evaluate the laboratory fracture resistance of teeth restored with crowns constructed in one of these materials (BelleGlass HP with and without fiber reinforcement.
40 sound maxillary premolar teeth were chosen and were allocated to four groups of 10 teeth, with the mean size of any group varying by less than 2.5% from other test groups. The teeth were stored in water. Each tooth was fixed in a steel mold and subjected to a standardized crown preparation. Crowns were constructed in belleGlass HP. Group A contained no fiber reinforcement. In Group B, Construct polyethylene braided fibers were applied from the mesial margin over the coronal aspect of the die down to the distal margin, and circumferentially around the preparation, prior to crown construction as in Group A. In Group C, a bundle of experimental S-glass fiber of 9 microm diameter was applied circumferentially prior to crown construction as in Group A. In Group D, two layers of Stick net pre-impregnated woven glass fibers were adapted over the whole surface of the initial thin coping, prior to constructing crowns as in Group A. Crowns were luted with a dual cure resin cement (Nexus), with the dentin surface of the specimens having first been treated with a dentin bonding system. Each specimen was stored under water at 37 degrees C for 24 hours prior to testing, and were then subjected to compressive loading at a cross-head speed of 1 mm/minute in a Universal Testing Machine by way of a 4 mm diameter steel bar placed along the midline fissure of the upper premolar crown.
The mean force required (kN) to cause fracture was as follows: Group A 2.0kN, Group B 2.4kN, Group C 2.7kN, Group D 2.3kN. ANOVA showed that there was no statistically significant difference between the groups.