Influence of time and adhesive system on the extrusion shear strength between feldspathic porcelain and bovine dentin

Influence of Ambient Temperature and Light-curing Moment on Polymerization Shrinkage and Strength of Resin Composite Cements

Objective:

The purpose of this study was to establish a clinically appropriate light-curing moment for resin composite cements while achieving the highest indirect tensile strength and lowest polymerization shrinkage.

Methods and Materials:

Polymerization shrinkage of seven resin composite cements (Multilink Automix, Multilink Speed Cem, RelyX Ultimate, RelyX Unicem 2 Automix, Panavia V5, Panavia SA plus, VITA Adiva F-Cem) was measured at ambient temperatures of 23°C and 37°C. Testing was done for autopolymerized and light-cured specimens after light application at either 1, 5, or 10 minutes after mixing. Indirect tensile strength of all cements was measured after 24 hours of storage at temperatures of 23°C and 37°C, for autopolymerized and light-cured specimens after light application 1, 5, or 10 minutes after mixing. To illustrate filler size and microstructures, SEM images of all cements were captured. Statistical analysis was performed with one-way ANOVA followed by post hoc Fisher LSD test (α=0.05).

Results:

Final polymerization shrinkage of the resin composite cements ranged from 3.2% to 7.0%. An increase in temperature from 23°C to 37°C as well as the light-curing moment resulted in material dependent effects on the polymerization shrinkage and indirect tensile strength of the cements. Polymerization shrinkage of the cements did not correlate with the indirect tensile strength of the cement in the respective groups. Highest indirect tensile strengths were observed for the materials containing a homogeneous distribution of fillers with a size of about 1 μm (Multilink Automix, Panavia V5, VITA Adiva F-Cem).

Conclusion:

The magnitude of the effect of light-curing moment and temperature increase on polymerization shrinkage and indirect tensile strength of resin composite cements is material dependent and cannot be generalized.

Shear bond, wettability and AFM evaluations on CO2 laser-irradiated CAD/CAM ceramic surfaces

The purpose of this study is to determine the CO₂ laser irradiation in comparison with sandblasting (Sb), hydrofluoric acid (Hf) and silane coupling agent (Si) on shear bond strength (SBS), roughness (Rg) and wettability (Wt) of resin cement to CAD/CAM ceramics. Sixty (CAD/CAM) ceramic discs were prepared and distributed into six different groups: group A, control lithium disilicate (Li); group B, control zirconia (Zr); group C, Li: CO₂/HF/Si; group D, Li: HF/Si; group E, Zr: CO₂/Sb/Si; group F, Zr: Sb/Si. Result showed significant difference between irradiated and non-irradiated in terms of shear bond strength for zirconia ceramics (p value = 0.014). Moreover, partial surface wettability for irradiated and non-irradiated ceramics. Irradiated surface demonstrated more rough surface in lithium disilicate than zirconia ceramics. CO₂ irradiation could increase shear bond strength, surface roughness and wettability for both CAD/CAM ceramics.

Correlation between clinical performance and degree of conversion of resin cements: a literature review

Resin-based cements have been frequently employed in clinical practice to lute indirect restorations. However, there are numerous factors that may compromise the clinical performance of those cements. The aim of this literature review is to present and discuss some of the clinical factors that may affect the performance of current resin-based luting systems. Resin cements may have three different curing mechanisms: chemical curing, photo curing or a combination of both. Chemically cured systems are recommended to be used under opaque or thick restorations, due to the reduced access of the light. Photo-cured cements are mainly indicated for translucent veneers, due to the possibility of light transmission through the restoration. Dual-cured are more versatile systems and, theoretically, can be used in either situation, since the presence of both curing mechanisms might guarantee a high degree of conversion (DC) under every condition. However, it has been demonstrated that clinical procedures and characteristics of the materials may have many different implications in the DC of currently available resin cements, affecting their mechanical properties, bond strength to the substrate and the esthetic results of the restoration. Factors such as curing mechanism, choice of adhesive system, indirect restorative material and light-curing device may affect the degree of conversion of the cement and, therefore, have an effect on the clinical performance of resin-based cements. Specific measures are to be taken to ensure a higher DC of the luting system to be used.

The effect of IDS (immediate dentin sealing) on dentin bond strength under various thermocycling periods

PURPOSE

The purpose of this study was to find out the effect of immediate dentin sealing (IDS) on bond strength of ceramic restoration under various thermocycling periods with DBA (dentin bonding agent system).

MATERIALS AND METHODS

Fifty freshly extracted human mandibular third molars were divided into 5 groups (1 control and 4 experimental groups) of 10 teeth. We removed enamel layer of sound teeth and embedded them which will proceed to be IDS, using All Bond II. A thermocycling was applied to experimental groups for 1, 2, 7, 14 days respectively and was not applied to control group. IPS Empress II for ceramic was acid-etched with ceramic etchant (9.5% HF) and silane was applied. Each ceramic disc was bonded to specimens with Duo-link, dual curable resin cement by means of light curing for 100 seconds. After the cementation procedures, shear bond strength measurement and SEM analysis of the fractured surface were done. The data were analyzed with a one-way ANOVA and Tukey multiple comparison test (α=.05).

RESULTS

There were no statistically significant differences between 4 experimental groups and control group, however the mean value started to decrease in group 7d, and group 14d showed the lowest mean bond strength in all groups. Also, group 7d and 14d showed distinct exposed dentin and collapsed hybrid layer was observed in SEM analysis.

CONCLUSION

In the present study, it can be concluded that ceramic restorations like a laminate veneer restoration should be bonded using resin cement within one week after IDS procedure.

Evaluation of the color reproducibility of all-ceramic restorations fabricated by the digital veneering method

PURPOSE

The objective of this study was to evaluate the clinical acceptability of all-ceramic crowns fabricated by the digital veneering method vis-à-vis the traditional method.

MATERIALS AND METHODS

Zirconia specimens manufactures by two different manufacturing method, conventional vs digital veneering, with three different thickness (0.3 mm, 0.5 mm, 0.7 mm) were prepared for analysis. Color measurement was performed using a spectrophotometer for the prepared specimens. The differences in shade in relation to the build-up method were calculated by quantifying ΔE(*) (mean color difference), with the use of color difference equations representing the distance from the measured values L(*), a(*), and b(*), to the three-dimensional space of two colors. Two-way analysis of variance (ANOVA) combined with a Tukey multiple-range test was used to analyze the data (α=0.05).

RESULTS

In comparing means and standard deviations of L(*), a(*), and b(*) color values there was no significant difference by the manufacturing method and zirconia core thickness according to a two-way ANOVA. The color differences between two manufacturing methods were in a clinically acceptable range less than or equal to 3.7 in all the specimens.

CONCLUSION

Based on the results of this study, a carefully consideration is necessary while selecting upper porcelain materials, even if it is performed on a small scale. However, because the color reproducibility of the digital veneering system was within the clinically acceptable range when comparing with conventional layering system, it was possible to estimate the possibility of successful aesthetic prostheses in the latest technology.

Effect of surface treatment on the bond strength between yttria partially stabilized zirconia ceramics and resin cement

STATEMENT OF PROBLEM

No consensus has been reached on the best bonding protocol between a zirconia ceramic surface and the tooth structure.

PURPOSE

The purpose of this study was to evaluate the extrusion shear strength between yttria partially stabilized zirconia ceramics and resin cement (Panavia F) after different surface treatments.

MATERIAL AND METHODS

The surface treatments evaluated (n=7) included the following: G1-control group (no surface treatment); G2-treated with MDP primer (Alloy Primer); G3-treated with 40% hydrofluoric acid (210 seconds); and G4-treated with 40% hydrofluoric acid (210 seconds) followed by MDP primer. The specimens were bonded to 2.5-mm-thick disks of bovine root dentin, and the extrusion shear tests were performed after they had been stored for 24 hours in distilled water at 37°C. The surface modifications were assessed on 2 specimens that were selected from each group by scanning electron microscopy. Data were analyzed with 1-way ANOVA and the Tukey-Kramer honestly significant difference test (α=.05).

RESULTS

G4 (mean 2.84, standard deviation [SD] 0.43 MPa) presented significantly higher (P<.001) extrusion shear strength when compared with the other groups in the study (G1: mean, 1.57; SD 0.28 MPa; G2: mean 1.46, SD 0.28 MPa; G4: mean 1.16, SD 0.41 MPa). No significant differences were found among the other groups in the study.

CONCLUSIONS

Yttria partially stabilized zirconia ceramics can be treated with 40% hydrofluoric acid for 210 seconds to increase the bond strength with the resin cement.

Shear bond strength of resin cement to an acid etched and a laser irradiated ceramic surface

PURPOSE

To evaluate the effects of hydrofluoric acid etching and Er,Cr:YSGG laser irradiation on the shear bond strength of resin cement to lithium disilicate ceramic.

MATERIALS AND METHODS

Fifty-five ceramic blocks (5 mm × 5 mm × 2 mm) were fabricated and embedded in acrylic resin. Their surfaces were finished with 1000-grit silicon carbide paper. The blocks were assigned to five groups: 1) 9.5% hydrofluoric-acid etching for 60 s; 2-4), 1.5-, 2.5-, and 6-W Er,Cr:YSGG laser applications for 60 seconds, respectively; and 5) no treatment (control). One specimen from each group was examined using scanning electron microscopy. Ceramic primer (Rely X ceramic primer) and adhesive (Adper Single Bond) were applied to the ceramic surfaces, followed by resin cement to bond the composite cylinders, and light curing. Bonded specimens were stored in distilled water at 37℃ for 24 hours. Shear bond strengths were determined by a universal testing machine at 1 mm/min crosshead speed. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-tests (α=0.05).

RESULTS

Adhesion was significantly stronger in Group 2 (3.88 ± 1.94 MPa) and Group 3 (3.65 ± 1.87 MPa) than in Control group (1.95 ± 1.06 MPa), in which bonding values were lowest (P<.01). No significant difference was observed between Group 4 (3.59 ± 1.19 MPa) and Control group. Shear bond strength was highest in Group 1 (8.42 ± 1.86 MPa; P<.01).

CONCLUSION

Er,Cr:YSGG laser irradiation at 1.5 and 2.5 W increased shear bond strengths between ceramic and resin cement compared with untreated ceramic surfaces. Irradiation at 6 W may not be an efficient ceramic surface treatment technique.

Shear bond strength between different materials bonded with two resin cements

BACKGROUND

The aim of this study was to compare the shear bond strength between Ni-Cr alloy specimens bonded to air-abraded Ni-Cr, bur-abraded Ni-Cr, etched ceramic and etched enamel substrates using the resin cements RelyX ARC or Enforce.

MATERIALS AND METHODS

Ni-Cr specimens were made and sandblasted with Al(2)O(3) airborne-particles. Disc-shaped patterns were made for each of the four experimental substrates: Ni-Cr treated with Al(2)O(3) airborne-particles, Ni-Cr treated with diamond bur abrasion, etched enamel and etched ceramic.

RESULTS

Significant differences in shear bond strength were found between the different materials and luting agents evaluated. The Ni-Cr alloy cylinders bonded to Ni-Cr surfaces sandblasted with 50 μm Al(2)O(3) particles and bonded with Enforce achieved the highest bond strength when compared with other substrates (28.9 MPa, p < 0.05). Bur-abraded metal discs had lowest values, regardless the cement used (2.9 and 6.9 MPa for RelyX and Enforce, respectively). Etched enamel and etched ceramic had similar shear bond strengths within cement groups and performed better when RelyX was used.

CONCLUSIONS

Bonding Ni-Cr to Ni-Cr and ceramic may result in similar and higher bond strength when compared to Ni-Cr/enamel bonding. For metal/metal bonding, higher shear bond strength was achieved with resin cement Enforce, and for metal/ceramic and metal/enamel bonding, RelyX had higher results.

Novel glass-ceramics for dental restorations

BACKGROUND

There are many different ceramic systems available on the market for dental restorations. Glass-ceramics are a popular choice due to their excellent esthetics and ability to bond to tooth structure allowing a more conservative approach. However, at present, these materials have insufficient strength to be used reliably in posterior regions of the mouth.

PURPOSE

The aim of this review article is to discuss the types of novel glass-ceramic currently be investigated including composition, microstructure and properties.

CONCLUSION

Current research in glass-ceramics focuses on the quest for a highly esthetic material along with sufficient strength to enable crowns and bridgework to be reliably placed in these areas.

CLINICAL SIGNIFICANCE

There is a gap in the market for a machinable resin bonded glass-ceramic with sufficient strength as well as excellent esthetics.

Tensile Bond Strength and Flexural Modulus of Resin Cements—Influence on the Fracture Resistance of Teeth Restored with Ceramic Inlays

The mechanical properties of resin cement can influence the fracture resistance of teeth restored with ceramic inlays. In general, cement with a higher elastic modulus resulted in a tooth/ceramic inlay that had a higher fracture resistance.

Extrusion shear strength between an alumina-based ceramic and three different cements

STATEMENT OF PROBLEM

Surface treatment is an essential step in bonding a ceramic to resin. Alumina ceramics are particularly difficult to prepare for adequate bonding to composite resin cements.

PURPOSE

The purpose of this study was to evaluate the bond strength between a densely sintered alumina ceramic and bovine dentin with 2 adhesive resin cements and a resin-modified glass ionomer cement using an extrusion shear strength test.

MATERIAL AND METHODS

Alumina cones (n=30), 4 mm in height, 3 mm in diameter at the small end, and with an 8-degree taper, were fabricated. Without any treatment, the cones were cemented in a standardized cavity in 2.5-mm-thick bovine dentin discs using 1 of 3 cement systems: Panavia F, RelyX ARC, or RelyX Luting. The cements were manipulated following the manufacturers' instructions. After 24 hours of storage at 37 degrees C, an extrusion shear test was performed in a universal testing machine at 0.5 mm/min until bonding failure. The data were analyzed using 1-way ANOVA and Tukey HSD test (alpha=.05). All fractured specimens were examined at x25 magnification and classified by fracture mode. Representative specimens were selected for SEM observation.

RESULTS

The highest strength values were obtained with Panavia F, and they were significantly higher (P<.05) than each of the other 2 cements, which were not significantly different from each other. Panavia F resulted in predominantly mixed failure and RelyX ARC and RelyX Vitremer showed primarily adhesive failure.

CONCLUSIONS

An MDP-containing adhesive system (Panavia F) provides better extrusion bond strength to a high-density alumina ceramic than a Bis-GMA resin luting agent system (RelyX ARC) or a resin-modified glass ionomer cement system (RelyX Luting).

Relationship between fracture toughness and flexural strength in dental porcelains

The aim of this study was to investigate the correlation between fracture toughness (K(Ic)) and flexural strength (FS) in dental porcelains. Porcelains with different leucite contents and clinical indications were used (A, B, C, D, and E). K(Ic) was determined by surface crack in flexure method (SCF) and FS was determined by four-point-bending test. Microstructural characterization was also carried out. The leucite contents of porcelains A, B, C, D, and E were, respectively, 22, 22, 6, 15, and 0%. Materials with higher leucite content (A and B) presented significantly higher K(Ic) values compared to materials with lower leucite content (C and E). The Weibull moduli (m) of porcelains A and B were statistically higher than those of the other three materials. Regarding characteristic strength (sigma(0)), porcelains D and E showed similar values and statistically higher than those of the other materials which were statistically different from each other. According to the regression analysis, sigma(0) increased with the increase of K(Ic) until approximately 0.75 MPa m(1/2). After that, the increase in K(Ic) was accompanied by a decrease in sigma(0). However, the Weibull modulus increased with the increase in K(Ic), especially for values greater than 0.80 MPa m(1/2).

Influence of dentin bonding agents and polymerization modes on the bond strength between translucent fiber posts and three dentin regions within a post space

STATEMENT OF PROBLEM

Debonding is the most frequent failure encountered with translucent fiber posts and usually occurs along the post space dentin-adhesive interface.

PURPOSE

The purpose of this study was to evaluate the effect of different dentin bonding agents and polymerization modes on the bond strength between translucent fiber posts and root dentin in different regions of the post space.

MATERIAL AND METHODS

Forty maxillary canines with similar root lengths were selected, sectioned at the cemento-enamel junction, and the roots were endodontically treated. Following post space preparation, the roots were divided into 4 groups of 10 specimens each, and the post spaces were treated with 1 of 4 different dentin bonding agents: light-polymerized, single-bottle bonding agent Excite (Group EX); dual-polymerized, single-bottle bonding agent Excite DSC (Group EX-DSC); self-etching primer Clearfil Liner Bond 2V with a light-polymerized bonding agent, Bond A (Group CL-LC); or self-etching primer Clearfil Liner Bond 2V with a dual-polymerized bonding agent, Bond A+B (Group CL-DC). Translucent fiber posts (D.T. Light-Post), 2.2 mm in diameter, were luted (Panavia F) in each specimen after respective dentin bonding procedures. The roots were cut into 3-mm-thick sections, perpendicular to the long-axis in cervical, middle, and apical post space dentin. Push-out tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min, and bond strength values (MPa) were calculated by dividing the force at which bond failure occurred by the bonded area of the post. The data were analyzed with 1- and 2-way analysis of variance and Tukey multiple comparison tests (alpha=.05). Dentin adhesive bonding mechanisms in different regions of the post spaces were evaluated with a scanning electron microscope.

RESULTS

The highest mean bond strength values were obtained for Group CL-LC (18.3 +/- 4.1 MPa). The dual-polymerized bonding agent resulted in significantly lower bond strength (P<.001) in combination with self-etching primer (Group CL-DC) (13.2 +/- 2.5 MPa). The light-polymerized and dual-polymerized single-bottle bonding agents provided similar bond strengths (12.7 +/- 5.0 for EX; 13.5 +/- 5.3 for EX-DSC). The regional bond strength values of single-bottle bonding agents were reduced significantly in apical post space dentin (P<.001). Self-etching primers did not demonstrate regional differences in post space dentin bonding and dense resin tags were apparent.

CONCLUSION

Data suggests that the self-etching primer system used in this study was unaffected by the morphological variations in the post space dentin compared to the single-bottle bonding agents. Dual polymerization did not improve the bond strength values of the bonding agents tested.

The influence of different core material on the FEA-determined stress distribution in dental crowns

OBJECTIVES

All ceramic restorations without metal have great advantages in their biocompatibility and aesthetic aspects. With the introduction of new core materials, the cores are sufficiently strong to produce long lasting all-ceramic restorations; however, the stresses in the veneering porcelain could still determine the longevity. The objective of this study was to evaluate, by finite element analysis (FEA), the influence of different core materials on the stress distribution in dental crowns.

METHODS

The model of a multi-layer all-ceramic crown for posterior tooth 46 produced with CAD-CAM-technology was translated into a three-dimensional FEA program. This crown model was made with gold, zirconia, and alumina-based porcelain core and their matching veneering porcelains. The stress distribution due to the combined influences of bite forces, residual stresses caused by the difference in expansion coefficient of the core material and the veneering porcelain, and the influence of shrinkage of the cement was investigated.

RESULTS

Stiffer core material does not always for various reasons result in lower stresses in the veneering porcelain.

SIGNIFICANCE

This study indicates that the actual distribution of the tensile stresses and the design of restorations must be taken into account; otherwise, the significant contribution of stronger and tougher core materials to the performance of all-ceramic restorations may be offset by the weaker veneering porcelain.

Finite element analysis model to simulate the behavior of luting cements during setting

OBJECTIVES

Besides the fixation of the restoration, an important function of dental luting cements is to seal the gap between tooth and restoration. However, as a result of adhesion, curing contraction is hindered, creating stresses. To maintain the seal these stresses neither exceed the bond nor the cohesive strength of the cement. The aim of this study was to evaluate a rather simple model, which mimics the setting behavior of luting cements based on the division of the setting process into a liquid, visco-elastic and elastic phase, for its suitability to predict in Finite Element Analysis (FEA) the magnitude of the setting stresses occurring clinically.

METHODS

Commercial luting cement, RelyX ARC, was used in this study. In a dynamic test set-up the stresses, the elastic strain, and the shrinkage were determined. Two layers with different thicknesses and different ratios between bonded and free surface (C-factor) were examined. The parameters were used in three-dimensional FEA models. The experimental contraction stresses were compared with the results of the FEA.

RESULTS

In cement layers with uniform layer thickness, it is possible to predict the contraction stresses with the found parameters. The smallest plastic deformations and contraction stresses were found in the thinnest layer. The studied model was reliable in predicting the experimental stresses.

SIGNIFICANCE

The results of this study may be used for the prediction using FEA of the actual stresses occurring in dental restorations.

Influence of ceramic thickness and polymerization mode of a resin luting agent on early bond strength and durability with a lithium disilicate–based ceramic system

STATEMENT OF PROBLEM

Attenuation of polymerization light energy by translucent all-ceramic materials may result in insufficient polymerization of underlying resin luting agents and inadequate early bond strength and durability. There is little information regarding the selection of an appropriate polymerization mode for cementing translucent all-ceramic restorations.

PURPOSE

The purpose of this study was to evaluate the influence of ceramic thickness and polymerization mode on the early bond strength and bond durability of a lithium disilicate-based ceramic system.

MATERIAL AND METHODS

The occlusal surfaces of 120 extracted, intact, human third molars were sectioned to expose a flattened area of dentin. The surface was etched with 32% phosphoric acid, and a single-step adhesive (One-Step) was applied to the etched dentin surfaces. Ceramic specimens (Empress 2), 6 mm in diameter and 1 mm, 1.5 mm, or 2 mm thick (n=40 per group), were fabricated using fluoropolymer resin matrixes. Each specimen was ground flat. Following hydrofluoric acid etching and silane treatment, ceramic discs of each thickness were further divided into 2 groups (n=20 per group) and bonded to the dentin surfaces with a dual-polymerized resin luting agent (Illusion), either with a catalyst (dual polymerization) or without a catalyst (light polymerization). A shear bond test was performed after 10 minutes (n=10) or after 24 hours following 1000 thermal cycles between 5 degrees C and 55 degrees C and a dwell time of 30 seconds (n=10). Debonded dentin surfaces were examined with SEM. The data were analyzed with 3-way analysis of variance (ANOVA) (alpha=.05).

RESULTS

The shear bond strengths ranged between 13.2 +/- 4.1 MPa and 15.9 +/- 2.0 MPa. Three-way ANOVA revealed that ceramic thickness, polymerization mode, storage time, or combinations of these parameters did not influence shear bond strength. The location of failure for all specimens was adhesive, between the dentin surface and bonding agent.

CONCLUSION

Both light polymerization and dual polymerization provided similar early shear bond strengths for the lithium disilicate-based ceramic system (Empress 2). The bond strength was not dependent on the thickness of the ceramic material tested. Durability of the bond was similar for both of the polymerization modes.

The influence of design parameters on the FEA-determined stress distribution in CAD–CAM produced all-ceramic dental crowns

INTRODUCTION

Knowledge of factors, which influence stress and its distribution is of key importance to the successful production of durable all-ceramic restorations. The objective of this study was to evaluate, by finite element analysis (FEA), the influence of the shape of the preparation and the cement layer on the stress distribution in CAD-CAM produced all-ceramic crowns and in their cement layer.

MATERIAL AND METHODS

The CAD models of multi-layer all-ceramic crowns for posterior tooth 46 of three patients produced with CAD-CAM-technology were translated into a three-dimensional FEA program. The stress distribution due to the combined influences of bite forces, residual stresses caused by the difference in expansion coefficient of the two ceramic layers, and the influence of shrinkage of the cement was investigated.

RESULTS

The tensile stresses in the crown for the chamfer knife-edge preparation might put the integrity of the currently available ceramic materials at risk, while a non-uniform cement layer might result in stresses exceeding the bond strength. It was concluded that for long lasting restorations in the posterior region it is advisable to make a chamfer with collar preparation, the cement layer as uniform, and the difference in thermal expansion for the two ceramics as small as possible.

SIGNIFICANCE

This study indicates that for full ceramic crowns in the posterior region, specific design rules should be followed, and that FEA utilizing CAD-CAM data can be a successful tool to develop design guidelines for all-ceramic restorations.

Marginal and internal adaptation of class II restorations after immediate or delayed composite placement

Direct class II composite restorations still represent a challenge, particularly when proximal limits extend below the CEJ. The aim of this in vitro study was to evaluate the influence of the type of adhesive and the delay between adhesive placement and composite insertion on restoration adaptation. Direct class II MOD box-shaped composite restorations (n=8 per group) were placed on intact human third molars, with proximal margins 1mm above or under CEJ. All cavities were filled with a horizontal layering technique, immediately after adhesive placement (IP) or after a 24h delay (DP). A filled three-component adhesive (OptiBond FL: OB) and a single-bottle, unfilled one (Prime & Bond 2.1: PB) were tested. Marginal adaptation was assessed before and after each phase of mechanical loading (250000 cycles at 50 N, 250000 cycles at 75 N and 500000 cycles at 100 N); internal adaptation was evaluated after test completion. Gold-plated resin replicas were observed in the SEM and restoration quality evaluated in percentages of continuity (C) at the margins and within the internal interface, after sample section. Adaptation to beveled enamel proved satisfactory in all groups. After loading, adaptation to gingival dentin degraded more in PB-IP (C=55.1%) than PB-DP (C=86.9%) or OB-DP (C=89%). More internal defects were observed in PB samples (IP: C=79.2% and DP: C=86.3%) compared to OB samples (IP: C=97.4% and DP: C=98.3%). The filled adhesive (OB) produced a better adaptation than the 'one-bottle' brand (PB), hypothetically by forming a stress-absorbing layer, limiting the development of adhesive failures. Postponing occlusal loading (such as the indirect approach) improved also restoration adaptation.