The role of dental implant abutment design on the aesthetic outcome: preliminary 3-month post-loading results from a multicentre split-mouth randomised controlled trial comparing two different abutment designs.

PURPOSE: To evaluate whether there are aesthetic and clinical benefits to using a newly designed abutment (Curvomax), over a conventional control abutment (GingiHue). MATERIALS AND METHODS: A total of 49 patients, who required at least two implants, had two sites randomised according to a split-mouth design to receive one abutment of each type at seven different centres. The time of loading (immediate, early or delayed) and of prosthesis (provisional crowns of fixed prosthesis) was decided by the clinicians, but they had to restore both implants in a similar way. Provisional prostheses were replaced by definitive ones 3 months after initial loading, when the follow-up for the initial part of this study was completed. Outcome measures were: prosthesis failures, implant failures, complications, pink esthetic score (PES), peri-implant marginal bone level changes, and patient preference. RESULTS: In total, 49 Curvomax and 49 GingiHue abutments were delivered. Two patients dropped out. No implant failure, prosthesis failure or complication was reported. There were no differences at 3 months post-loading for PES (difference = -0.15, 95% CI -0.55 to 0.25; P (paired t test) = 0.443) and marginal bone level changes (difference = -0.02 mm, 95% CI -0.20 to 0.16; P (paired t test) = 0.817). The majority of the patients (30) had no preference regarding the two abutment designs; 11 patients preferred the Curvomax, while five patients preferred the GingiHue abutments (P (McNemar test) = 0.210). CONCLUSIONS: The preliminary results of the comparison between two different abutment designs did not disclose any statistically significant differences between the evaluated abutments. However the large number of missing radiographs and clinical pictures casts doubt on the reliability of the results. Longer follow-ups of wider patient populations are needed to better understand whether there is an effective advantage with one of the two abutment designs.

Mechanical behavior of bulk direct composite versus block composite and lithium disilicate indirect Class II restorations by CAD-FEM modeling.

OBJECTIVES: To study the influence of resin based and lithium disilicate materials on the stress and strain distributions in adhesive class II mesio-occlusal-distal (MOD) restorations using numerical finite element analysis (FEA). To investigate the materials combinations in the restored teeth during mastication and their ability to relieve stresses. METHODS: One 3D model of a sound lower molar and three 3D class II MOD cavity models with 95° cavity-margin-angle shapes were modelled. Different material combinations were simulated: model A, with a 10µm thick resin bonding layer and a resin composite bulk filling material; model B, with a 70µm resin cement with an indirect CAD-CAM resin composite inlay; model C, with a 70µm thick resin cement with an indirect lithium disilicate machinable inlay. To simulate polymerization shrinkage effects in the adhesive layers and bulk fill composite, the thermal expansion approach was used. Shell elements were employed for representing the adhesive layers. 3D solid CTETRA elements with four grid points were employed for modelling the food bolus and tooth. Slide-type contact elements were used between the tooth surface and food. A vertical occlusal load of 600 N was applied, and nodal displacements on the bottom cutting surfaces were constrained in all directions. All the materials were assumed to be isotropic and elastic and a static linear analysis was performed. RESULTS: Displacements were different in models A, B and C. Polymerization shrinkage hardly affected model A and mastication only partially affected mechanical behavior. Shrinkage stress peaks were mainly located marginally along the enamel-restoration interface at occlusal and mesio-distal sites. However, at the internal dentinal walls, stress distributions were critical with the highest maximum stresses concentrated in the proximal boxes. In models B and C, shrinkage stress was only produced by the 70µm thick resin layer, but the magnitudes depended on the Young's modulus (E) of the inlay materials. Model B mastication behavior (with E=20GPa) was similar to the sound tooth stress relief pattern. Model B internally showed differences from the sound tooth model but reduced maximum stresses than model A and partially than model C. Model C (with E=70GPa) behaved similarly to model B with well redistributed stresses at the occlusal margins and the lateral sides with higher stress concentrations in the proximal boxes. Models B and C showed a more favorable performance than model A with elastic biomechanics similar to the sound tooth model. SIGNIFICANCE: Bulk filling resin composite with 1% linear polymerization shrinkage negatively affected the mechanical behavior of class II MOD restored teeth. Class II MOD direct resin composite showed greater potential for damage because of higher internal and marginal stress evolution during resin polymerization shrinkage. With a large class II MOD cavity an indirect composite or a lithium disilicate inlay restoration may provide a mechanical response close to that of a sound tooth.

The Evaluation of Unscrewing Torque Values of Implant-Abutment Connections: An In Vitro Study.

PURPOSE: This study investigated the stability of titanium screws in implant-abutment connections by measuring the force necessary to induce unscrewing. MATERIALS AND METHODS: A total of 60 implant-abutment couplings were assigned to two groups (n = 30 each). The sequence 10-20-32 Ncm was tested in Group 1; the sequence 10-20-32-32-32 Ncm was tested in Group 2. The force necessary to unscrew each abutment-implant sample was recorded and statistically analyzed. The significance level was set at P < .05. RESULTS: Significant differences were found between the two sequences. Group 2 required higher forces than Group 1 to unscrew. CONCLUSION: The stability of the implant-abutment joint may be improved by tightening with the sequence 10-20-32-32-32 Ncm.

The use of bonded partial ceramic restorations to recover heavily compromised teeth.

Restorative procedures are accompanied by a reduction of tooth stability, a decrease of fracture resistance, and an increase in deflection of weakened cusps. The choice between a direct or an indirect restorative technique, mainly in posterior areas, is a challenge, and involves biomechanical, anatomical, functional, esthetic, and financial considerations. In this article, the pros and cons of direct restorations are examined, as well as an analysis of indirect restorations and an overview of dental ceramics. In particular, several clinical uses of lithium disilicate overlays with a circumferential adhesive ferrule effect are proposed: heavily compromised vital teeth with thin walls, cracked teeth, and endodontically treated molars. Clinical procedures are described step by step on the basis of data from scientific literature. In conclusion, the use of lithium disilicate in combination with adhesive technologies can lead to a more conservative, economic, and esthetic approach in the restoration of heavily compromised teeth.

Effect of 2 impression techniques on the dimensional accuracy of working implant prosthesis models: an in vitro study.

PURPOSE: Implant impressions and working models form integrated precision systems for registration and transmission of clinical data. The components of implant systems have a dimensional tolerance capable of introducing inaccuracies in the impression, thus in the prosthetic framework. This article aimed at comparing 2 repositioning impression techniques: one using impression copings (conventional technique) and the other using the final abutments as impression copings (interceptive technique). MATERIALS AND METHODS: Two experimental models, one with 4 parallel implants and the other with 4 nonparallel implants, were used to make silicone impressions. Twenty impressions were made with the conventional technique, and a further 20 were made with the interceptive technique. Three-dimensional images acquired with a three-dimensional scanner were measured using a three-dimensional image analysis software, comparing models obtained from the impressions with the experimental models. Data were statistically analyzed by means of confidence intervals calculated with the mean (α = 0.05), descriptive (box plot), and bivariate analyses. RESULTS: Statistic analysis highlighted significant differences among models obtained using both techniques: the interceptive technique generated working models with less distortion and variability. CONCLUSIONS: For internal-connection implants, the interceptive technique provided significantly more precise working models than did the conventional technique.

The evaluation of marginal gap with and without optical aids: clinicians versus technicians.

PURPOSE: This study investigated the reliability of visual assessment of marginal gaps in relation to the use of magnification and the operator's profession. MATERIALS AND METHODS: A titanium bar was notched, simulating 40 marginal gaps, and 35 operators performed a quantitative evaluation of the incisions. RESULTS: Visual examination was neither sensitive nor specific, as an extreme variability of data was recorded. The precision of readers improved with magnification aids only for clinicians; technicians were significantly more accurate in evaluating the incision's width. CONCLUSION: The visual examinations were inadequate to decide the clinical acceptability of a restoration with regard to its marginal fit.

Microleakage in class II restorations: open vs closed centripetal build-up technique.

PURPOSE: This study evaluated whether a Class II restoration in a flowable resin composite has to be placed prior to (open-sandwich technique) or after (closed-sandwich technique) construction of the interproximal wall in the centripetal build-up technique in order to reduce microleakage. METHODS AND MATERIALS: Thirty non-carious molars were selected and randomly divided into two groups (n = 15). A standardized Class H preparation was made with the cervical margin 1 mm below the cementum-enamel junction. In Group 1, flowable resin composite was applied as a 1 mm base, remaining exposed at the cervical margin. In Group 2, the hybrid resin composite was applied to the interproximal wall, followed by a layer of flowable composite on the pulpal floor, away from the margins. The restorations were then subjected to 500 thermal cycles, each with a dwell time of 20 seconds at 5 degrees C and 55 degrees C. Adaptation at the cervical margin was evaluated by dye penetration and SEM analysis using the replica technique. The data were statistically analyzed using the Mann-Whitney U-test (p < 0.05). RESULTS: The centripetal open-sandwich technique led to significantly lower dye penetration than the centripetal closed-sandwich technique (p < 0.001). CONCLUSION: Flowable resin composite placed under hybrid resin composites in Group 1 provided better marginal adaptation and fewer voids. However, neither Group 1 nor Group 2 was able to completely prevent microleakage.

Microtensile bond strength of a resin cement to a novel fluorcanasite glass-ceramic following different surface treatments.

OBJECTIVES: This study evaluated the effect of surface treatments on the bond strength of fluorcanasite and lithium disilicate glass-ceramics, with the possibility of eliminating HF etching of these ceramics. METHODS: Fifteen blocks of an experimental fluorcanasite and a lithium disilicate glass-ceramic (IPS e.max CAD) were assigned to one of the following three surface treatments: (1) machined with 60 microm finish, (2) machined and grit blasted, (3) machined and HF etched. The ceramic blocks were duplicated in composite resin (Spectrum) and cemented together with a resin luting agent (Variolink II). Thirty microbars per group (1.0 x 1.0 x 20 mm) were obtained and subjected to a tensile force at a crosshead speed of 0.5 mm/min using a universal testing machine until failure. The mode of failure was determined using scanning electron microscopy. The appropriate bonding procedure was assessed for durability by storing in water at 100 degrees C for 24 h. Statistical analyses were performed with ANOVA and Tukey's test (P<0.05). RESULTS: Machining alone significantly increased the bond strength (MPa) of the fluorcanasite (27.79+/-6.94) compared to the lithium disilicate (13.57+/-4.52) (P<0.05). HF etching resulted in the lowest bond strength (8.79+/-2.06) for the fluorcanasite but the highest for the lithium disilicate (24.76+/-9.38). Regarding durability, the machined fluorcanasite (15.24+/-5.46) demonstrated significantly higher bond strength than the machined and HF etched lithium disilicate (12.28+/-3.30). SIGNIFICANCE: The fitting surface of the fluorcanasite glass-ceramic should retain the machined finish and be directly treated with silane. The use of HF acid is contraindicated.

The effect of different surface treatments on bond strength between leucite reinforced feldspathic ceramic and composite resin.

OBJECTIVES: The aim of this study was to evaluate the effect of different surface treatments on the microtensile bond strength between a leucite reinforced glass-ceramic and composite resin. METHODS: Leucite reinforced ceramic blocks (n=24) were constructed using the hot pressing technique. The blocks were assigned to 4 groups, which received the following surface treatments: G1: hydrofluoric (HF) acid and silane; G2: silane alone; G3: HF acid and silane then dried with warm air (100 degrees C); G4: silane alone then dried with warm air (100 degrees C). Unfilled resin was applied, followed by composite resin. Specimens were prepared and loaded in tension to determine the microtensile bond strength. Failure modes were classified by stereo- and scanning electron microscopy (SEM). Data was analysed using Kruskal-Wallis test followed by the Dunn's multiple range test. RESULTS: The groups including the warm air step (G3 and G4) achieved a significantly stronger adhesion than G1 and G2. Pre-treatment of the surface with hydrofluoric acid in G1 resulted in significantly higher bond strength than G2. Failures were mostly cohesive in the luting resin for G1, G3 and G4 and mainly adhesive at the ceramic-resin interface in G2. CONCLUSIONS: The method of application of silane to the ceramic surface can have a significant influence on the adhesion between the ceramic restoration and the resin cement. Enhancing the condensation reaction by drying the silane with a 100C warm air stream significantly improved the microtensile bond strength, possibly eliminating the need for the hydrofluoric acid etching step.

Effect of air-drying temperature on the effectiveness of silane primers and coupling blends in the repair of a microhybrid resin composite.

PURPOSE: To evaluate the effect of different silane agents and air-drying temperatures on the repair strength of a microfilled hybrid composite. MATERIALS AND METHODS: Composite cylinders (8 x 4 mm) of Gradia Direct Anterior (GC, N=36), stored in a saline solution at 37 degrees C for 1 month, were sandblasted (50-microm aluminium oxide), cleaned (35% phosphoric acid) and randomly divided into six groups (n=6). Two prehydrolyzed silane primers (Monobond-S, Ivoclar-Vivadent, Porcelain Primer, Bisco), a non prehydrolyzed silane primer (Porcelain Liner M, Sun Medical) and three silane/adhesive coupling agents (Porcelain Bond Activator-PBA/Clearfil New Bond, PBA/Clearfil SE Bond, PBA/Clearfil Tri-S Bond, Kuraray) were investigated. Silane-coated surfaces were air dried at two different temperatures (23 degrees C and 38 degrees C) and repairs (8 x 8 mm) were fabricated (Gradia Direct Anterior). Unrepaired composite cylinders (8 x 8 mm, n=6) were used as control to evaluate the cohesive strength of the material. Microtensile bond strength measurements (microTBS) were performed. RESULTS: The silane agent applied (p < 0.001), the airdrying temperature (p < 0.001) and their interaction (p < 0.001) were significant factors (two-way ANOVA, Tukey test; p < 0.05). Silane primers achieved inferior microTBS when air dried at 23 degrees C as compared to silane/adhesive blends. Warm air-drying was significantly beneficial to composite repairs mediated by silane primers. Comparable results were achieved by silane/adhesive couplings at 23 degrees C and 38 degrees C. At 38 degrees C all the intermediate agents resulted in repair microTBS that were comparable to the 24-h cohesive strength of the composite (one-way ANOVA, Dunnett t-tests; p < 0.05). CONCLUSION: The chemical interactions between silane primers and compozite substrate may be optimized through warm airdrying. Silane/adhesive couplings were not influenced by the air drying temperature.

A clinical trial of Empress II porcelain inlays luted to vital teeth with a dual-curing adhesive system and a self-curing resin cement.

PURPOSE: The aim of the study was to clinically evaluate Empress II inlays cemented with a dual-curing bonding agent and a self-curing luting system. MATERIALS AND METHODS: Forty patients were selected to receive one Empress II inlay. Empress II is a heat-pressed glass ceramic containing lithium disilicate and lithium orthophosphate crystals, purported to provide higher stress resistance and improved strength. The restorations were placed between March and May 2000. Recalls were performed after 6, 12, 24, and 36 months. At the 3-year recall, 7 patients were lost to follow-up. Inlays were evaluated for postoperative sensitivity, marginal integrity, marginal leakage, color stability, surface staining, retention, and surface crazing (microcracks). RESULTS: At the 3-year recall, all the restorations were in place and only one showed postoperative sensitivity (at the first recall, 1 week after placement). Only 3 inlays showed slight marginal staining, and 4 inlays showed gaps, with little surface staining or microcracks. CONCLUSIONS: No inlay debonded or fractured during theobservation period. All the evaluated inlays were in place and acceptable.

Evaluation of the adhesion of fiber posts to intraradicular dentin.

The interfacial strength and ultrastructure of a total-etch, self-etch and self-adhesive resin cement used to lute endodontic glass fiber posts (FRC Postec, Ivoclar-Vivadent) was assessed with the "thin-slice" push-out test and transmission electron microscopy (TEM). The tested adhesive cements were Variolink II (Ivoclar-Vivadent), Panavia 21 (Kuraray Co) and RelyX Unicem (3M ESPE). In each group, seven posted roots were used for push-out tests and two were processed for TEM observations. The interfacial strength achieved by Variolink II (10.18 +/- 2.89 MPa) was significantly higher than Panavia (5.04 +/- 2.81 MPa) and RelyX Unicem (5.01 +/- 2.63 MPa), which were comparable to each other. TEM micrographs of the interface between Variolink II and intraradicular dentin revealed that the smear layer was totally removed and an 8-10 micron thick hybrid layer was formed. In the other group specimens, the smear layer was not completely dissolved and smear plugs were retained. Gaps were present between the hybridized complex and the adhesive layer in the Panavia 21 specimens and between the smear layer and underlying root dentin in the RelyX Unicem specimens. Interfacial strengths and microscopic findings were in agreement and indicated that the bonding potential of the total-etch resin cement was greater. The acidic-resin monomers responsible for substrate conditioning in Panavia 21 and RelyX Unicem appeared unable to effectively remove the thick smear layer created on root dentin during post space preparation.

The contribution of friction to the dislocation resistance of bonded fiber posts.

This study tested the null hypothesis that the use of dentin adhesives produces no improvement on the fixation of fiber posts with resin cements in endodontically treated teeth. Post spaces were prepared in 36 single-rooted root-filled teeth. Silanized glass fiber posts were cemented to the post spaces using a self-etch (ED primer/Panavia 21) and a total etch resin cement (Excite DSC/Variolink II), with or without the accompanying dentin adhesives. Fixation strengths and interfacial ultrastructure were evaluated using a "thin slice" push-out test and transmission electron microscopy. For both resin cements, the fixation strengths obtained from specimens luted with resin cement only did not differ significantly from those in which the intraradicular dentin was first bonded with a dentin adhesive. In the presence of incomplete smear layer removal and interfacial gaps, the dislocation resistance of bonded fiber posts was contributed largely by sliding friction.

In vitro evaluation of wall-to-wall adaptation of a self-adhesive resin cement used for luting gold and ceramic inlays.

PURPOSE: This in vitro study evaluated the wall-to-wall adaptation of a new self-adhesive resin-based cement (RelyX Unicem) in comparison with that of other cements when luting gold and porcelain inlays in standardized Class II cavities in extracted teeth. MATERIALS AND METHODS: In each experimental group (n = 10), a different combination of inlay and luting material was tested. Group 1: Porcelain Empress II (Ell) and RelyX Unicem (U); group 2: Ell and resin-based cement Variolink II in combination with primer and bonding Excite DSC; group 3: gold inlays (G) and U; group 4: G and Harvard zinc-oxy-phosphate cement; group 4: G and glass-ionomer cement Fuji Cem. After storage and thermocycling, microleakage testing was carried out and dye penetration was examined at the occlusal and cervical margins of each inlay. The differences in microleakage score were tested for statistical significance first comparing all groups, then pooling the groups for inlay material (Kruskal-Wallis nonparametric ANOVA and Mann-Whitney U test, p < 0.05). SEM observations of the tooth/cement/restoration interfaces were also made in each group. RESULTS: Harvard cement had the highest microleakage. The sealing ability exhibited by RelyX Unicem was satisfactory with both gold and porcelain inlays, and comparable to that of Fuji Cem and Variolink II. CONCLUSION: RelyX Unicem achieved an adequate seal on both enamel and dentin when used to lute in vitro gold and porcelain inlays.

The adhesion between fiber posts and root canal walls: comparison between microtensile and push-out bond strength measurements.

Aim of the study was to compare the trimming and non-trimming variants of the microtensile technique with the 'micro' push-out test in the ability to measure accurately the bond strength of fiber posts luted inside root canals. In 15 endodontically treated teeth (Group A), fiber posts were cemented with Excite DSC in combination with Variolink II (Ivoclar-Vivadent). In 15 roots RelyX Unicem (3M-ESPE) was used for fiber post luting (Group B). Within each group, the bond strength of cemented fiber posts was assessed with the trimming and non-trimming microtensile technique, as well as with the push-out test. The great number of premature failures (16.9% in Group A, 27.5% in Group B) and the finding of high standard deviation values make questionable the reliability of the trimming microtensile technique. With the non-trimming microtensile technique, only five sticks were obtained from a total of six roots. The remaining specimens failed prematurely during the cutting phase. With the push-out test no premature failure occurred, the variability of the data distribution was acceptable, and regional differences in bond strength among root levels could be assessed. Relatively low values of bond strength were, in general, recorded for luted fiber posts. In conclusion, when measuring the bond strength of luted fiber posts, the push-out test appears to be more dependable than the microtensile technique.

Sealing ability of packable resin composites in class II restorations.

PURPOSE: To evaluate in Class II restorations the marginal adaptation of ten packable composite resins in combination with the proprietary adhesive system. MATERIALS AND METHODS: Standard Class II cavities were prepared in 100 extracted molars. The sample was randomly divided into ten groups. In each group, one specific packable composite was tested in association with its own adhesive: Groups: 1) Scotchbond1/FiltekP60; 2) Etch & Prime3.0/Definit; 3) Prime & Bond 2.1/SureFil; 4) Excite/Tetric Condensable; 5) Gluma/Solitaire; 6) Kerr Bonding/Prodigy Condensable; 7) One-step/Pyramid; 8) Tenure/Virtuoso; 9) Syntac/Cavex Packable; 10) Excite/Tetric flow/Tetric Ceram. The restored teeth were sectioned at three levels in the mesiodistal direction and processed for the microleakage test. On each section, the degree of dye penetration along the margins of the restoration was assessed, and the differences in the leakage given by the ten materials at either the occlusal or the cervical margin were evaluated for statistical significance. A statistical analysis was also conducted to assess the significance of the differences between the scores recorded at the occlusal margin and those measured at the cervical margin of the restoration. RESULTS: In general, the scores recorded at the cervical margin were significantly higher than those measured at the occlusal margin (p < 0.05). When all of the groups were compared for microleakage at the occlusal margin, the only significant difference revealed by the statistical analysis was that the specimens treated with Etch&Prime 3.0 and Definit (group 2) exhibited a marginal adaptation significantly worse than that seen in groups 1, 3, 4, 6, 8, 10. CONCLUSION: The application of a thin layer of a flowable composite at the cervical margin as a liner underneath the packable composite enhanced the marginal adaptation of the restoration. The use of a self-etching primer to condition the dental substrate resulted at the occlusal margin in greater microleakage than when phosphoric acid was applied.

Efficacy of self-etching primer on sealing margins of Class II restorations.

PURPOSE: To evaluate sealing ability of different types of restorative-adhesive combinations and to correlate etch patterns with leakage scores. MATERIALS AND METHODS: 56 molars were selected and divided randomly in four groups of 14 specimens each. A standardized adhesive Class II preparation with the cervical margin placed 1 mm below the CEJ and an occlusal reduction of 2 mm was performed. No bevels were utilized in the preparation. Four combinations of bonding system/restorative material were tested. Group 1: Excite (EX) in combination with Tetric Ceram (TC) as control; Group 2: Prompt-L-Pop (PP1) applied for 15 seconds in combination with TC; Group 3: Etch and Prime 3.0 in combination with Definite restorative material (EP); Group 4: Prompt-L-Pop (PP2) applied for 30 seconds in combination with TC. The bonding systems (Groups 1, 2 and 3) and all restorative materials were used following strictly manufacturers' instructions. The resin composite was applied following an incremental technique. Ten specimens of each group were processed for leakage test. The specimens were sectioned with a diamond saw in three different areas in mesial-distal direction. Two different operators evaluated the sections blindly for scoring leakage at cervical and occlusal margins. The highest score for the sections of each tooth area was selected for scoring and further statistical analysis. The results of the staining measurements were statistically evaluated using the Kruskal-Wallis non-parametric analysis of variance with Bonferroni alpha protection. The level of statistical significance was defined as P<0.05. The remaining four specimens of each group were kept in a 37% HCl solution for 48 hours to dissolve the dental structures and to observe the resin replica of the cavities by SEM. RESULTS: EX showed less dye penetration at occlusal margins than the other three groups, while no statistically significant differences were found at the dentin margin. The SEM observations showed rougher and more uniform enamel etch pattern when phosphoric acid (EX) was applied than that obtained with self-etching adhesive systems. Resin tags and adhesive lateral branches were noted in all groups at the dentin site.

Marginal integrity of ceramic inlays luted with a self-curing resin system.

OBJECTIVE: Aim of this study was to observe the efficacy of two different composite cements on the prevention of marginal deterioration around adhesive ceramic inlay restorations, under laboratory conditions, and to test the null hypothesis that different luting procedures cannot affect sealing ability of luted inlays. METHODS: Twenty-six standardized mesio-occlusal Class II cavities were prepared in extracted posterior teeth. Class II inlays were fabricated with IPS Empress II system following the manufacturer's instructions. The samples were divided into two groups of 13 teeth each at random. Group 1: The ceramic inlays of Group 1 were luted using Excite DSC and an experimental self-curing resin cement (Multilink, Vivadent); in this group, Excite DSC was self-activated and not light-cured. Group 2: Excite DSC in combination with a dual-curing resin cement (Variolink II, Vivadent) was used (as control). In this group Excite DSC was light-cured for 20s separately, before resin cement application. The 'wet' bonding technique was followed. Three samples of each group were selected at random for SEM observations, while the other 10 samples were processed for marginal leakage. The bonding mechanism to dentin and resin cement thickness was evaluated. RESULTS: Samples of both groups showed resin tag and adhesive lateral branch formation. In Group 1 the hybrid layer was mainly uniform along the interface between dental substrates and adhesive material, and resin cement thickness was between 20 and 85 microm. At the cervical margin no gap was detected. In Group 2 the cement thickness was between 30 and 110 microm and hybrid layer formation was observed along the interface but at the cervical margin it was not always uniform and continuous. Resin tag formation was uniform in both groups. At cervical margins, 80% of Group 1 samples showed a perfect seal at the dentin-cementum margins, and 90% at enamel margins. Group 2 samples showed only 50% of cervical margins free from leakage and 80% at the occlusal enamel margins. Statistically significant differences were found at cervical margins between the two groups, while no significant differences were found at enamel site. CONCLUSIONS: It can be concluded that the self-curing adhesive-resin cement combination can properly seal Class II porcelain inlays.