Mixed Class V restorations: the potential of a dentine bonding agent

The marginal micromorphology and seal of mixed Class V restorations (i.e. restorations with margins located 50 per cent in dentine and 50 per cent in enamel) using Scotchbond VLC or Scotchbond 2 bonded to dentine in conventional and saucer-shaped cavities were evaluated. The four operative systems tested included a two-step incremental filling technique using the light-curing composite Silux, two direct inlay techniques using Silar or Silux as a luting cement and an inlay technique utilizing a Ca(OH)2 liner. All restoration types showed poor marginal adaptation in dentine irrespective of cavity design and bonding agent used. The inlay technique, tested in seven different variations, did not optimize marginal adaptation. Cavity lining with the Ca(OH)2 base material adversely affected dentine bonding. In mixed Class V restorations, marginal adaptation at the dentinal cavosurface line angle continues to pose a problem.     

Microleakage of indirect inlays placed on different kinds of glass ionomer cement linings

The objective of this study is to compare the marginal seal of Class II cavities restored with indirect inlays constructed on glass ionomer cement linings having different curing properties. Also the effect of acid-etching of these liners on microleakage was investigated. Mesio-occlusal and disto-occlusal cavities in 80 extracted human molars having the cervical floor below the cementoenamel junction were prepared (n:160). Half of the preparations were restored with Ceramco II porcelain and the rest with SR-Isosit resin inlay material. Liners as light curing Ionoseal light+chemically curing LCL 8 and Zionomer and chemically curing Ketac-Bond glass ionomer cements (GICs) were used. On mesial preparations GICs were acid-etched but were not on distal preparations. All inlays were cemented with Ultrabond composite material. After thermocycling the teeth were placed in a basic fuchsin dye solution for 24 h, then each tooth was sectioned. By using a stereomicroscope the extent of marginal leakage was scored and statistically evaluated. Microleakage was observed beneath all GIC linings and was more extensive between light curing GIC/dentine interface. By acid-etching of GICs the microleakage between GIC/dentine interface was increased significantly. Whether acid-etching was applied or not a significantly increased microleakage was recorded between chemically curing GIC/composite interfaces. Although the marginal microleakage was witnessed in both inlays, it appeared that porcelain inlays provided a better marginal seal, in comparison to SR-Isosit inlays.     

Quantitative in vivo evaluation of four restorative concepts for mixed Class V restorations

This study was performed in vivo over a 6-month period to assess restorative margins in Class V restorations placed with different techniques. The margins were evaluated quantitatively under the scanning electron microscope using the replica technique. Results indicated that the sandwich technique using a glass-ionomer cement base and a composite resin restoration was not able to prevent marginal gaps in dentin. However, the experimental Gluma/Clearfil system resulted in a quality of dentinal margins not statistically significantly different from that of enamel margins. These in vivo findings substantiate in vitro results.     

Microleakage of glass ionomer/composite resin restorations: A laboratory study. 1. The influence of glass ionomer cement

Acid-etching of enamel margins, often combined with bevelling and use of a low viscosity resin, has resulted in improved sealing of composite restorations. When enamel is absent and margins involve dentine or cementum, microleakage is more often observed. The use of glass ionomer cement, as both a restorative material and as a base combined with a veneer of composite resin, has been advocated as a means of minimizing microleakage where margins are placed in dentine or cementum. Four restorative techniques incorporating glass ionomer cement were used, in vitro, to restore cervical cavities. After thermal cycling, dye penetration was scored along occlusal and gingival margins. In all instances the gingival margin exhibited a less reliable seal than the occlusal margin. The sandwich restorations produced a superior seal at both occlusal and gingival margins when compared with glass ionomer restorative cement.     

Effect of multi-step dentin bonding systems and resin-modified glass ionomer cement liner on marginal quality of dentin-bonded resin composite Class II restorations

The use of resin composites in the restoration of Class II cavities with gingival margins located in dentin is still controversial. The purpose of this in vitro study was to evaluate the effect of four state-of-the-art multi-step dentin-bonding systems (A. R. T. Bond, Syntac, OptiBond DC, Scotchbond Multipurpose) on marginal adaptation and microleakage of dentin-bonded composite Class II restorations. A total of 72 Class II cavities with gingival margins in dentin were prepared in extracted molars and filled with fine-hybrid composites using a three-sited light curing technique. In one half of the cavities the pulpal wall was lined with a resin-modified glass ionomer cement liner (RM-GIC), in the other half a total bonding technique was applied. A. R. T. Bond and Syntac were tested with selective enamel etching (SE) and total etching (TE). Marginal adaptation was evaluated in a scanning electron microscope before and after thermocycling (TC). Microleakage was determined by dye penetration. After TC the proportions of continuous margin in dentin ranged from 37% (Syntac/SE) to 91.2% (A. R. T. Bond/TE). Scotchbond Multipurpose exhibited the lowest degree of microleakage (0.22 mm). Marginal enamel fracture was the most prevalent marginal defect at the enamel margins (8.3–22.2%). The use of the RM-GIC had no beneficial effect on any of the marginal parameters, either in dentin or in enamel. It is concluded that low degrees of marginal gap formation and microleakage can be achieved in totally bonded composite Class II restorations when using state-of-the-art multi-step bonding systems in combination with a meticulous incremental filling technique. Received: 6 April 1998 / Accepted: 25 August 1998     

Amalgam alternatives – micro‐leakage evaluation of clinical procedures. Part I: direct composite/composite inlay/ceramic inlay

This study investigated the degree of dye penetration with three different types of tooth‐coloured restorations. Twenty‐four intact extracted molars were collected. The teeth were immediately stored in water at room temperature. Class II cavity preparations were prepared and restored with three different types of tooth‐coloured restorations: A, composite resin in the incremental technique; B, composite inlay technique; and C, ceramic inlay. Specimens were subjected to 700 cycles of thermal stress. They were than immersed in 2% basic fuchsin dye. The teeth were sectioned in three planes before being ranked as to the amount of dye penetration. The highest score obtained on three plano‐parallel sections was adopted as the representative value. The three groups were compared using the Kruskal Wallis non‐parametric test. Dye penetration was significantly lower at the enamel margins when using the composite inlay system and the incremental technique compared to the ceramic inlay technique. The restorations placed using the composite inlay technique showed less dye penetration than the incremental technique at the dentine margins ( P < 0·017).     

Effect of different luting materials on the marginal adaptation of Class I ceramic inlay restorations in vitro.

OBJECTIVES: The aim of this in vitro study was to assess the marginal adaptation of prefabricated Class I ceramic inlay restorations placed with various luting materials. METHODS: Forty-two standardized occlusal cavities were prepared in extracted human molars with diamond burs exactly corresponding to the dimensions of prefabricated glass ceramic inlays. The prepared teeth were randomly assigned to seven groups of six teeth each and restored using (1). the composite resin Tetric Ceram in increment technique [Group I] or (2). ceramic inlays (Cerana) luted with: the composite based materials Dual Cement [Gr. II] and Panavia 21 [Gr. III], the compomer material Dyract Cem [Gr. IV], Dyract Cem with additional use of Prime & Bond 2.1 [Gr. V], the silicophosphate cement Trans-Lit [Gr. VI], or the ethylcyanoacrylate Cyano-Veneer [Gr. VII]. Marginal adaptation was evaluated by SEM-analyses before and after thermal cycling (2500 cycles; 5-55 degrees C) and mechanical loading (100N; 500000 cycles) using replica models. Kruskal-Wallis H-test and Mann-Whitney U-test were used for statistical analyses. RESULTS: Group I (increment technique) as well as Groups II-V (inlay technique) revealed high percentages of perfect marginal adaptation in over 95% of the analyzed margins, both before and after thermo-mechanical loading. Statistical significant differences could not be detected within these groups. All inlays luted with silicophosphate cement (Group VI) and four of six inlays applied with Cyano-Veneer (Group VII) fractured under occlusal load. SIGNIFICANCE: A stable bonding to the enamel and to the ceramic inlay was achievable with the composite luting resins Dual Cement and Panavia 21 as well as with the compomer based luting material Dyract Cem but not with the use of the silicophosphate cement Trans-Lit or the ethylcyanoacrylate Cyano-Veneer.     

Indications for self-cured and light-cured adhesive composite resins.

Self-cured and light-cured adhesive composite resins have biologic advantages and disadvantages. In contrast to the self-cured composite resin, the light-cured composite resin has a greater tendency to separate from a cavity wall and gingival margin. Alternative methods of insertion such as the incremental technique and cement liner have decreased the tendency to separate, but have failed to completely eliminate the problem. The light-cured composite resin may also fracture the marginal enamel rods. The light-cured composite resin is indicated for shallow facial restorations and veneers. The self-cured composite resin is indicated to restore deeper cavities, those with a dentinal gingival margin, and for occlusal restorations.     

Marginal integrity of large compomer Class II restorations with cervical margins in dentine

OBJECTIVES: The aim of the present study was to investigate the marginal integrity of total-bond Dyract AP restorations in large Class II restorations with cervical margins in dentine. The efficacy of a new non-rinse conditioner and the effect of beveling the enamel margins were also studied. METHODS: Large MOD cavities with cervical margins located 1mm below the CEJ were prepared in 48 extracted human molars. Six groups (n=8) were filled using a total-bond technique with Spectrum TPH or Dyract AP or a sandwich technique with Dyract in combination with Spectrum TPH. For Dyract AP total-bond restorations, a new non-rinse conditioner was tested vs. a total-etch with 36% phosphoric acid in beveled and butt-joint cavities. After water storage for 21 days and thermocycling (2000x, 5-55 degrees C), replicas were produced for quantitative marginal analysis in the SEM. Afterwards, teeth were immersed in 0.5% basic fuchsin for 24h and dried. Percent dye penetration over the total margin length was analysed in three layers using a sequential grinding technique. Statistical analysis was performed with non-parametric tests and the Bonferroni correction for multiple comparisons at p<0.05. RESULTS: All restoration types showed microleakage. On cervical margins in dentine, Dyract AP restorations showed better marginal adaptation than Spectrum TPH total-bond restorations (marginal openings (MO), median 33.8 vs. 79.6%), but were inferior to Dyract/Spectrum TPH sandwich restorations (MO: 0. 0%). The non-rinse conditioner improved the marginal adaptation of Dyract AP restorations in dentine (MO: 4.7 vs. 38.4%, p=0.0206 for beveled cavities, 12.2 vs. 33.8%, p=0.0238, for butt-joint cavities) and yielded similar results in enamel margins provided that enamel margins were beveled. Beveling of enamel significantly reduced the occurrence of enamel microcracks. CONCLUSIONS: The use of a non-rinse conditioner in combination with Dyract AP may improve the marginal adaptation of Class II restorations compared to composite restorations. The sandwich technique with Dyract results in better marginal adaptation in cervical dentine compared to all other restorative techniques tested in this study. However, microleakage cannot predictably be prevented with the sandwich technique.     

Marginal adaptation of class V composite restorations submitted to thermal and mechanical cycling

Objective:

This study evaluated the effect of the margin location and an adhesive system on the marginal adaptation of composite restorations.

Material and Methods:

Class V cavities were prepared in bovine teeth with the gingival margin on the dentin and the incisal margin on the enamel. The cavities were restored with a micro-hybrid composite resin using an etch-and-rinse [Single Bond 2 (SB)] or a self-etching adhesive [Clearfil SE Bond (CL)]. After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500 x magnification). The higher gap width in each margin was recorded (T0). After the first evaluation, the samples were submitted to thermal cycling (2,000 cycles of 5ºC±2ºC followed by 55ºC±2ºC - T1) and mechanical cycling (100,000 cycles of 50 kN and 2 Hz - T2). Replicas of samples were rebuilt after each cycling and analyzed under SEM. The data were submitted to Mann-Whitney, Wilcoxon and Friedman testing (a=0.05).

Results:

The SB presented higher gaps in the dentin than the enamel, while there was no difference between the substrate for the CL. In the dentin, the CL showed better marginal sealing than the SB. The opposite occurred in the enamel. There were no significant differences between the baseline, thermal and mechanical cycling for any experimental condition.

Conclusions:

The outcomes of the present study showed that the adhesive system and margin location have an important effect on the marginal adaptation of composite restorations.     

Proximo-cervical adaptation of Class II-composite restorations after thermocycling: a quantitative and qualitative study

summary Sixty caries-free extracted human molars were used to determine the proximo-cervical adaptation and sealing of Class II-composite restorations related to the location of the cavity margins: 1.0 mm or 0.5 mm coronal to the cementum-enamel-junction (CEJ), at the CEJ, and 0.5 mm apical to the CEJ. All cavities were filled with a hybride type composite resin, which was combined at the CEJ and apical to the CEJ with a dentine adhesive in half of the specimens. The proximo-cervical adaptation and sealing was determined before and after thermocycling (TC, 2000 cycles, 5–55°C) by SEM and dye penetration tests. Furthermore, an analysis of the interfaces between the enamel or dentine and the filling material was performed to determine whether or not there is a significant correlation between micromorphological factors of the dental hard tissues (enamel acid etch pattern, dentine resin tag pattern) and the marginal adaptation of the composite restorations. The data were statistically evaluated by means of H-tests (Kruskall–Wallis), U-tests (Mann–Whitney), and Chi²-tests (P < 0.05). It was found that the proximo-cervical adaptation is statistically significant dependent on the position of the margin. 1.0 mm coronal to the CEJ an excellent marginal sealing was found before and after TC, whereas all other groups revealed a significant deterioration of the marginal integrity after TC. Using a dentine adhesive significantly improved the marginal sealing in cavities at the CEJ before and after TC, however the marginal quality was not achieved as in the case of the normally structured enamel 1.0 mm coronal to the CEJ following acid etching. In defects 0.5 mm apical to the CEJ the dentine adhesive only improved the cervical adaptation before TC. The evaluation of the tooth/ filling interfaces revealed that there is no statistically significant correlation between the enamel acid etch pattern resp. dentine resin tag pattern and the marginal sealing.     

Marginal adaptation of direct composite and sandwich restorations in Class II cavities with cervical margins in dentine

OBJECTIVES: The aim of this study was to evaluate the marginal adaptation of direct Class II sandwich restorations with resin-modified glass-ionomer cements and compomers in comparison to base and total bond restorations. For sandwich restorations with a triple cure resin-modified glass-ionomer cement the influence of different light curing techniques was also evaluated. METHODS: Large butt-joint class II cavities with cervical margins 1 mm below the cemento-enamel junction were cut into 120 extracted human molars. The cavities (15 groups, n = 8) were filled using a sandwich, base or total bond technique with materials from five different manufacturers. A three-sited light curing technique was used in 13 groups. For the material combination Vitremer/Z100 two additional groups with a different wand positioning and a metal matrix were evaluated. After water storage for 21 days and thermocycling (2000x, 5-55 degrees C), replicas were quantitatively analysed in the SEM. Statistical analysis was performed with the Kruskal-Wallis test and the Bonferroni test at p < 0.05. RESULTS: The marginal adaptation of vertical enamel margins was not dependent on the restorative technique. For margins in dentine, marginal adaptation was significantly better with the sandwich technique than with a base or total bond technique for all materials. There were no significant differences between the base and total bond technique. Overall, resin-modified glass-ionomer cements showed somewhat better results than compomers in sandwich restorations, though differences were not significant for some criteria. Vitremer/Z100 sandwich restorations applied with a metal matrix showed the highest mean percentage of excellent margins of all experimental groups. CONCLUSIONS: Both resin-modified glass-ionomer cements and compomers can improve the marginal quality when used in a sandwich technique. Further research is necessary to determine the ideal material combination for sandwich restorations.     

Replica patterns on composite restorations performed in vivo with different acid-etch restorative procedures

243 experimental Class V restorations using a chemically cured composite resin were inserted in human third molars with the conventional acid-etch restorative procedure and eight modifications of this technique. The teeth were extracted after 4 months and, following demineralization, the filings were examined in SEM concerning their enamel and dentin replica patterns on the inner cavity faced surface. Results showed a significant correlation between the enamel replica patterns and the marginal adaptation of the restorations while the dentin replica patterns did not influence the in vivo adaptation. Furthermore it was found that the improved adaptation obtained by low viscous resin applied as an intermediary layer in etched cavities is due to fewer porosities in the restorative material interface with enamel and dentin. Beveling of preparations prevents stress-induced fractures of unsupported enamel prisms along the cavity periphery. Treatment of etched cavities with the surface active comonomer NPG-GMA increases the general interfacial contact between resin restoratives and cavity walls, and surface coating of finished and re-etched restorations fills up spaces created along cavity margins during the filling and finishing procedure.     

Marginal seal of composite inlays using different polymerization techniques

summary The effect of indirect and semi-direct curing systems of Cl II composite inlays on microleakage was investigated in vitro and compared to conventional direct posterior composite restorations. Nearly identical Cl II cavities were restored with the same composite resin using different polymerization systems. Microleakage assessment was carried out after cyclic loading and thermal stressing by assessing the dye penetration. The data showed that all inlay techniques resulted in improved marginal sealing compared with conventional restorations. However, the indirect procedure resulted in significantly reduced microleakage compared to the semi-direct inlay techniques.     

Marginal seal of cervical tooth-coloured restorations. A laboratory investigation of placement techniques

Incremental placement of composite resin has been suggested as a means of overcoming the contraction that occurs during polymerization of the composite material and as a consequence should allow an improved gingival dentine seal. Numerous incremental placement techniques for composite resin restorations have been documented in the literature. This study examined four different methods of placing Silux in class V cavities, located in the region of the cemento-enamel junction, and lined with Vitrabond.
None of the placement methods used completely sealed either the enamel or dentine margins. Of the four techniques employed, the one which involved incremental placement of the gingival component first showed the least amount of leakage at the dentine margin. This result, however, was only significantly different from that of the bulk placement method.
In the majority of cases where leakage did occur at the dentine margin, it progressed no further than the Vitrabond lining. It appeared that the high initial adherence to dentine of the light cured glass-ionomer cement prevented deeper penetration of the dye.     

Marginal adaption of Class V restorations with and without "softstart-polymerization"

Polymerization shrinkage causing marginal gap formation is still a major problem in light curing restorations. The aim of the present study was to test the influence of "softstart polymerization" (prepolymerization at a low light intensity followed by a final cure at a high light intensity) on the marginal integrity of polyacid-modified resin and composite resin restorations in Class V cavities using a commercially available curing unit with two defined curing intensities. Sixty standardized Class V cavities were prepared. Twenty cavities at a time were filled either with a composite resin [Spectrum + Prime & Bond 2.1 (SP)], or with polyacid-modified resins [Dyract + Prime & Bond 2.1 (DY); Hytac + OSB Primer (HY)]. Ten fillings of each group were either conventionally cured (40 seconds, 800 mW/cm2), or they were cured with a lower starting intensity (10 seconds, 150 mW/cm2) and then with the full intensity (30 seconds, 800 mW/cm2). Margins were evaluated before and after thermomechanical loading (TCML) by quantitative margin analysis. Microleakage was assessed by dye penetration. The softstart polymerization showed no significant influence on gap formation for each material and interface before and after TCML. Quantitative margin analysis after TCML showed significantly fewer marginal gaps at the enamel/restoration interface for SP (0%) compared to DY (15.5%) and HY (44.5%) using softstart polymerization. At the dentin/restoration interface the corresponding results for gap formation were 29.6% for SP, 8.5% for DY, and 21.0% for HY. These results were not significantly different from each other. Dye penetration was significantly higher for SP at the dentin/restoration interface. SP showed significantly more marginal swelling at the dentin/restoration interface compared to DY. In conclusion, softstart polymerization using a very low starting intensity did not improve the marginal adaptation of polyacid-modified resins or composite resins in Class V cavity preparations. The best marginal adaptation in Class V cavities at the enamel/restoration interface was achieved with SP, using the acid-etch technique. In dentin, however, the polyacid-modified resins showed a superior marginal adaptation.     

Interfacial gaps following ceramic inlay cementation vs direct composites

This study compared the interfacial integrity of Class II ceramic inlay restorations and direct resin composite restorations. The influence of a flowable resin composite liner was also evaluated. Class II DO cavities were prepared in 40 recently extracted mandibular molars and assigned to four treatment groups. Group A: direct composite restoration; Group B: Cerec inlays fabricated and cemented with a resin cement; Group C: adhesive lining with a flowable resin composite used prior to resin composite restoration; Group D: lining with a flowable resin composite prior to cementation of Cerec inlays. After finishing, polishing and thermocycling (4 degrees C and 60 degrees C x 500), the samples were cross-sectioned in a mesio-distal direction along the center of the fillings or inlays. The cross-sectioned surface was polished, and the adhesive interfaces between resin and enamel or dentin were observed under a scanning laser measurement microscope. Ceramic inlay restorations showed no interfacial gaps in enamel, but direct resin composite restorations showed a significantly higher incidence of gaps at the interface or cracks in the interfacial enamel (p=0.0002). No differences were found in the resin-dentin interfaces for both the inlay and direct resin composite restorations. The use of a flowable resin composite as an adhesive liner produced a significantly greater gap-free resin-dentin interface in Cerec inlay and direct resin composite restorations (p=0.0233 & 0.0009), but it did not reduce gap formation at the resin-enamel interface.     

Replica patterns on composite restorations performed in vivo with different acid-etch restorative procedures

Abstract 243 experimental Class V restorations using a chemically cured composite resin were inserted in human third molars with the conventional acid-etch restorative procedure and eight modifications of this technique. The teeth were extracted after 4 months and, following demineralization, the fillings were examined in SEM concerning their enamel and dentin replica patterns on the inner cavity faced surface. Results showed a significant correlation between the enamel replica patterns and the marginal adaptation of the restorations while the dentin replica patterns did not influence the in vivo adaptation. Furthermore it was found that the improved adaptation obtained by low viscous resin applied as an intermediary layer in etched cavities is due to fewer porosities in the restorative material interface with enamel and dentin. Beveling of preparations prevents stress-induced fractures of unsupported enamel prisms along the cavity periphery. Treatment of etched cavities with the surface active comonomer NPG-GMA increases the general interfacial contact between resin restoratives and cavity walls, and surface coating of finished and re-etched restorations fills up spaces created along cavity margins during the filling and finishing procedure.     

Selective enamel etching: effect on marginal adaptation of self-etch LED-cured bond systems in aged Class I composite restorations

The aim of this study was to evaluate the influence of previous enamel etch and light emitting diode (LED) curing on gap formation of self-etch adhesive systems in Class I composite restorations after thermomechanical aging (TMA). Thus, on 192 human molars, a box-shaped Class I cavity was prepared maintaining enamel margins. Self-etch adhesives (Clearfil SE and Clearfil S3) were used to restore the preparation with a microhybrid composite. Before application of the adhesives, half of the teeth were enamel etched for 15 seconds with 37% phosphoric acid; the other half were not etched. For the photoactivation of the adhesives and composite, three light-curing units (LCUs) were used: one polywave (Ultra-Lume LED 5, UL) and two single-peak (FlashLite 1401, FL and Radii-cal, RD) LEDs. After this, epoxy resin replicas of the occlusal surface were made, and the specimens were submitted to TMA. New replicas were made from the aged specimens for marginal adaptation analysis by scanning electron microscopy. Data were submitted to Kruskal-Wallis and Wilcoxon tests (α=0.05). Before TMA, when enamel was etched before the application of S3, no gap formation was observed; however, there were gaps at the interface for the other tested conditions, with a statistical difference (p≤0.05). After TMA, the selective enamel etching previous to the S3 application, regardless of the LCU, promoted higher marginal adaptation compared to the other tested groups (p≤0.05). Prior to TMA, higher marginal integrity was observed, in comparison with specimens after TMA (p≤0.05). With regard to Clearfil SE and Clearfil Tri-S cured with FL, no differences of gap formation were found between before and after aging (5.3 ± 3.8 and 7.4 ± 7.5, respectively), especially when the Clearfil Tri-S was used in the conventional protocol. When cured with RD or UL and not etched, Clearfil Tri-S presented the higher gap formation. In conclusion, additional enamel etching promoted better marginal integrity for Clearfil Tri-S, showing it to be an efficient technique for Class I composite restorations. The two-step self-etch adhesive was not influenced by selective enamel etching or by the LED-curing unit.     

Self-etch vs etch-and-rinse adhesives: effect of thermo-mechanical fatigue loading on marginal quality of bonded resin composite restorations.

OBJECTIVE: This study evaluated the marginal integrity of dentine adhesives bonded to enamel and dentine, before and after thermo-mechanical loading (TML). METHODS: MO cavities with proximal boxes beneath the CEJ were prepared in extracted human third molars. Direct resin composite restorations (Tetric Ceram) were bonded with 3-step etch-and-rinse (Syntac Classic, Solobond Plus, OptiBond FL), 2-step etch-and-rinse (Admira Bond, Single Bond), 2-step self-etch (AdheSE, Clearfil SE Bond), and 1-step self-etch (all-in-one) adhesives (Adper Prompt, Xeno III, iBond). Marginal gaps were analyzed using SEM of epoxy resin replicas. Bonded interfaces before TML were examined with TEM to identify pre-existing attributes for subsequent marginal disintegration. RESULTS: In enamel, high percentages of gap-free margins were initially identified for all adhesives. After TML, etch-and-rinse adhesives exhibited significantly higher percentages of gap-free margins (approximately 90%) compared with two-step self-etch (approximately 75%) and all-in-one (approximately 55%) adhesives (p<0.05). iBond did not completely etch through the enamel smear layer. In dentine, 89-100% gap-free margins were initially observed. After TML, there were no statistical differences among etch-and-rinse (62-70%) and two-step self-etch (62-63%) adhesives (p>0.05). The all-in-one adhesives exhibited significantly less gap-free margins (<40%) in dentine (p<0.05), with iBond showing the worst marginal integrity (15%). The presence of pre-existing water channels within the adhesives probably expedited water sorption when restorations were under functional stresses. CONCLUSION: Enamel bonding was more effective with phosphoric acid-etching. Etch-and-rinse and 2-step self-etch adhesives showed promising marginal adaptation to dentine and may have a better clinical prognosis than the all-in-one bonding approach.