Fracture strength of custom-fabricated Celay all-ceramic post and core restored endodontically treated teeth.
(17/60)
BACKGROUND: The increased use of all-ceramic crown provides a rationale for tooth-colored core. Due to superior mechanical properties, Vita Celay infiltration ceramic developed for crown and bridge works presents the potential for fabricating all-ceramic posts and cores in one piece. This study was conducted to compare the fracture strength of endodontically treated teeth which were thereafter given different types of posts and cores and crowns restoration, respectively. The evaluated post-and-core systems are: custom-fabricated Celay all-ceramic post-core, custom cast metal post-core, and prefabricated stainless steel post (Parapost) with and without 2.0 mm dentine ferrule. METHODS: Sixty freshly extracted human maxillary central incisors were endodontically treated and randomly divided into five groups with 12 samples each. Group A: Celay ceramic post-cores restored teeth with 2.0 mm dentine ferrule. Group B: Celay ceramic post-cores restored teeth with no dentine ferrule. Group C: cast metal post-cores restored teeth with 2.0 mm dentine ferrule. Group D: cast metal post-cores restored teeth with no dentine ferrule. Group E: prefabricated post and composite cores restored teeth with 2.0 mm dentine ferrule. All teeth were restored with Celay ceramic crowns. Each specimen was subjected to a load at a 45-degree angle to the long axis on MTS 810 material testing machine until failure, at crosshead speed of 0.02 cm/minute. Analysis of variance followed by the Newman-Keuls pairwise multiple comparison tests were used to compare the results of the groups tested. RESULTS: There was a statistically significant difference among the five groups (P < 0.01). Celay ceramic post-cores restored teeth with 2.0 mm dentine ferrule [(758.35+/-19.26) N] and cast metal post-cores restored teeth with 2.0 mm dentine ferrule [(756.63+/-66.22) N] had a significantly greater mean fracture strength than the other three groups in which no significant difference was observed. The 2.0 mm dentine ferrule could cause significant fracture resistance alteration of Celay post-core restored teeth. CONCLUSIONS: When covered with Celay ceramic crowns, Celay post-cores restored teeth with 2.0 mm dentine ferrule and cast metal post-cores restored teeth with 2.0 mm dentine ferrule have similar fracture strength. There was a statistically significant difference between the fracture resistance of Celay post-core restored teeth with and without 2.0 mm dentine ferrule. (+info)
Effect of curing method of a dual-cure resin cement on monkey pulpal reaction after bonding of tooth-colored inlay.
(18/60)
To compare the pulpal responses to light-cured and self-cured resin cements, cervical cavities were prepared in monkey's teeth, followed by application of etching gel and adhesive (Single Bond). A dual-cure resin cement (RelyX ARC) was applied, and hybrid composite inlays (Estenia) were bonded to the cavities. In one group, the cavities were photoirradiated for 20 seconds and the resin cement light-cured. In the other group, the resin cement was self-cured for six minutes without any photoirradiation. After experimental periods of seven, 28, and 70 days, histological features of pulp tissue were evaluated and compared. Results showed no significant differences in the histological features of the pulp tissues between the two curing methods. Both light-cured and self-cured resin cements showed acceptable biological compatibility with the monkey pulp. No bacterial penetration along the cavity walls was detected with either curing method. (+info)
Recent advances in materials for all-ceramic restorations.
(19/60)
The past 3 years of research on materials for all-ceramic veneers, inlays, onlays, single-unit crowns, and multi-unit restorations are reviewed in this article. The primary changes in the field were the proliferation of zirconia-based frameworks and computer-aided fabrication of prostheses, and a trend toward more clinically relevant in vitro test methods. This article includes an overview of ceramic fabrication methods, suggestions for critical assessment of material property data, and a summary of clinical longevity for prostheses constructed of various materials. (+info)
Finite element stress analysis of indirect restorations prepared in cavity bases.
(20/60)
The objective of this study was to analyze the distribution of tensile stresses in indirect restorations prepared in several composite cavity bases. Elastic moduli of 20 materials were measured by nanoindentation technique for finite element analysis. Axisymmetric models of posterior onlays were constructed using combinations of two onlay materials and three cavity base materials. Thickness of resin cement was 50 um. A vertical load of 95.5 N was applied on the cusp tip. Maximum stress of 18.1 MPa was found in the model consisting of a ceramic onlay and a flowable resin composite base. It was also found that tensile stress increased as the area of the base having a lower elastic modulus became wider. Base materials having higher elastic moduli were determined to be suitable as cavity base materials for posterior restorations. (+info)
Tooth structure and fracture strength of cavities.
(21/60)
This study evaluated, in vitro, the loss of tooth substance after cavity preparation for direct and indirect restorations and its relationship with fracture strength of the prepared teeth. Sixty sound human maxillary first premolars were assigned to 6 groups (n=10). MOD direct composite cavities (Groups I, II and III) and indirect inlay cavities (Groups IV, V and VI) were prepared maintaining standardized dimensions: 2-mm deep pulpal floors, 1.5-mm wide gingival walls and 2-mm high axial walls. Buccolingual width of the occlusal box was established at 1/4 (Groups I and IV), 1/3 (Groups II and V) or 1/2 (Groups III and VI) of the intercuspal distance. Teeth were weighed (digital balance accurate to 0.001 g) before and after preparation to record tooth substance mass lost during cavity preparation. The prepared teeth were submitted to occlusal loading to determine their fracture strength using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were analyzed by two-way ANOVA and Tukey test (alpha= 0.05). 1/4-inlay cavities had higher percent mean mass loss (9.71%) than composite resin cavities with the same width (7.07%). 1/3-inlay preparations also produced higher percent mean mass loss (13.91%) than composite resin preparations with the same width (10.02%). 1/2-inlay cavities had 21.34% of mass loss versus 16.19% for the 1/2-composite resin cavities. Fracture strength means (in kgf) were: GI = 187.65; GII = 143.62; GIII = 74.10; GIV = 164.22; GV = 101.92; GVI = 50.35. Statistically significant difference (p<0.05) were observed between Groups I and IV, II and V, III and VI. Higher tooth structure loss and lower fracture strength were recorded after preparation of inlay cavities, regardless of the width of the occlusal box, compared to the direct composite resin cavities. (+info)
Bond strength between luting materials and a fiber-reinforced resin composite for indirect restorations.
(22/60)
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. (+info)
Tensile bond strength of Er, Cr: YSGG laser-irradiated human dentin to composite inlays with two resin cements.
(23/60)
The purpose of this study was to investigate the tensile bond strength of composite inlays to human dentin with two different cavity preparation tools (bur versus Er, Cr: YSGG laser) and with two different bonding procedures (total-etch: Variolink II versus self-etch: Maxcem). The specimens were divided into four groups: bur-cut/Variolink II, bur-cut/Maxcem, laser-ablated/Variolink II, and laser-ablated/Maxcem. The following characteristics were then investigated: morphological change, dentin-resin cement interface, surface roughness, and tensile bond strength. Results demonstrated that the tensile bond strengths of the four groups were 19.11 +/- 5.88 MPa, 8.54 +/- 2.38 MPa, 13.72 +/- 3.43 MPa, and 12.11 +/- 3.71 MPa, respectively. We concluded that Variolink II provided higher tensile bond strength to composite inlays than Maxcem. On the other hand, the bond strength of Variolink II with dentin cavity prepared by Er, Cr: YSGG laser was statistically lower than that prepared by bur. (+info)
Effect of surface characteristics on adherence of S. mutans biofilms to indirect resin composites.
(24/60)
The purpose of this study was to evaluate the adherence of biofilms to the surfaces of two indirect resin composites, Estenia C&B and Gradia. Slabs were prepared from the materials, and then either ground with 800-grit silicon carbide paper or polished with diamond pastes up to 1 microm. Artificial biofilms of Streptococcus mutans were grown on the composite slabs in an artificial mouth system for 20 hours. Thereafter, the amounts of retained biofilm on the surfaces were measured after sonication. Surface characteristics of the resins--such as surface roughness, amount of residual monomers, and distribution of filler particles--were examined. Two-way ANOVA revealed that the amount of retained biofilm varied (p<0.05) according to the composition and surface roughness of the material. In particular, biofilm adherence was lowest on Estenia C&B slabs when polished with diamond pastes up to 1 microm. It was thus concluded that the surface roughness and composition of a resin composite influenced biofilm adherence. (+info)