Assessment of marginal leakage around Class II composite restorations in retrieved primary molars

The aim of the present investigation was to evaluate, by means of dye penetration, the microleakage around Class II composite restorations, in retrieved primary molars that functioned in the mouth for at least one year. The experimental material consisted of 13 exfoliated primary molars that had been restored with Herculite (Kerr Corporation, Romulus, Michigan 48174 USA) at least one year previously, utilizing an incremental or a bulk filling technique. The retrieved teeth were insulated with utility wax and nail polish, immersed in 2% basic fuchsin, embedded in acrylic resin, and ground off to various depths. The marginal leakage was assessed according the degree of dye penetration at the occlusal and cervical margins. No difference was observed between the two filling techniques. In most teeth, no leakage at the occlusal margins was observed; minimal leakage, limited to the enamel, was observed at the occlusal margins of two teeth, one of each filling technique. Severe penetration was evident at the cervical margin of three restorations, two of them filled incrementally and the third using the bulk technique. Mild to moderate penetration was observed at the cervical margin in the majority of the other restorations. It was concluded that an incremental filling technique could not eliminate microleakage at the cervical margins of Class II composite restorations.     

Microleakage of resin composite restorations with glass-ceramic inserts.

OBJECTIVE: The purpose of this study was to evaluate the effects of glass-ceramic inserts and different application techniques of resin composites on marginal leakage. METHOD AND MATERIALS: Three groups of 10 standardized, round, Class V cavities were prepared on the buccal surface of 30 extracted human molar teeth. Group 1 received resin composite restorations, placed in one increment (bulk). Group 2 received resin composite restorations that were placed in two increments, and group 3 received resin composite restorations with beta-quartz ceramic inserts. After the teeth were thermocycled and placed in 0.5% basic fuchsin for 24 hours, they were sectioned and examined for microleakage. RESULTS: On the occlusal margins, there was no statistically significant difference between the restorations placed with the incremental technique and the restorations with beta-quartz inserts. The restorations placed with the bulk technique had significantly more microleakage than did the others. On the gingival margins, the restorations with beta-quartz inserts exhibited significantly less microleakage than did the other groups. The restorations placed with the bulk technique showed significantly more dye penetration than did the others. CONCLUSION: The use of a glass-ceramic insert reduced the marginal leakage of Class V resin composite restorations.     

The effect of occlusal loading on the microleakage of class V restorations

OBJECTIVE: This in vitro study evaluated the microleakage of Class V cavities restored with a resin composite and different adhesive systems after occlusal loading. METHODS & MATERIALS: Standardized box-shaped Class V cavities were prepared on the buccal side of 135 non-carious human premolars. The teeth were randomly divided into three groups of 45 premolars each and restored as follows: Group 1-two-step total-etch adhesive (Single Bond, 3M) + resin composite (Supreme, 3M ESPE); Group 2-two-step self-etch adhesive (Clearfil SE, Kuraray) + resin composite and Group 3-one-step self-etch adhesive (Xeno III, Dentsply) + resin composite. The restorations were finished with aluminum oxide discs (Sof-Lex, 3M). Fifteen teeth in each group received 10,000 x 100 N and 250 N occlusal loads, respectively, and the remaining 15 teeth served as the control. The premolars were immersed in 2% methylene blue for 24 hours. The dye penetration was examined under a stereomicroscope, and the results were statistically analyzed by Kruskal Wallis, Mann-Whitney U and Wilcoxon Signed Rank tests to determine differences between the groups. RESULTS: Gingival margins showed more dye penetration than occlusal margins in all the tested groups (p<0.05). In all the tested adhesive systems, 100 N occlusal loading did not change dye penetration; however, Groups 1 and 2 exhibited better marginal sealing than Group 3 at the enamel margins under 250 N occlusal loading. CONCLUSION: Within the limitations of this in vitro study, it may be concluded that enamel margins provided better marginal sealing than dentin/cementum margins and the two-step self-etch adhesive exhibited better marginal sealing than an all-in-one adhesive at the enamel margins under 250 N occlusal loading.     

Microleakage of silorane- and methacrylate-based class V composite restorations

The marginal integrity of class V restorations in a silorane- and a group of methacrylate-based composite resins with varying viscosities was tested in the present study. Different adhesives (OptiBond FL, KerrHawe; AdheSE One, Vivadent; or Silorane System Adhesive, 3M ESPE) were applied to 168 standardized class V cavities. The cavities (n = 12) were filled with a wide range of different viscous composite resins: Filtek Silorane, 3M ESPE; els and els flow, Saremco; Tetric EvoCeram and Tetric EvoFlow, Vivadent; Grandio, Voco; and Ultraseal XT Plus, Ultradent. Microleakage of the restoration was assessed by dye penetration (silver staining) on multiple sections with and without thermocycling and mechanical loading (TCML: 5,000 × 5-55°C; 30 s/cycle; 500,000 × 72.5 N, 1.6 Hz). Data were statistically analyzed with the Mann-Whitney U test and the Error Rates Method (ERM). The silorane-based composite resin yielded the lowest dye penetration after TCML. Microleakage of methacrylate-based composite restorations, in general (ERM), was statistically significantly influenced by the adhesive system, Moreover, dye penetration at enamel margins was significantly lower than dye penetration at dentin margins. The chemical basis of composite resins and adjacent tooth substance seems to strongly influence marginal sealing of class V restorations for methacrylate-based materials. Moreover, the steps of dental adhesives used affected marginal integrity. The silorane-based composite resin evaluated in the present study exhibits the best marginal seal. The three-step adhesive yielded better marginal sealing than the one-step adhesive for methacrylate-based class V composite restorations.     

Microleakage of Class V restorations using two different compomer systems: an in vitro study

This study compared the marginal microleakage of Class V cavities restored with Dyract-AP and F2000. Forty Class V cavity preparations were performed on extracted human teeth. As a negative control, twenty teeth were used without Class V preparations. The apical foramina of the teeth were sealed with a layer of varnish and amalgam restorations. Class V cavity preparations with occlusal margins in enamel, and gingival margins in cementum or dentin that measured approximately three millimeters in width (gingival-occlusal) and length (mesial-distal), were prepared on the buccal surface of the teeth. Samples were divided randomly into 2 groups of 15, and restored per manufacturer's instructions using experimental primer/conditioner (PCC, D/C) and Single Bond Adhesive (3M). All restorations were polished with an abrasive finishing kit. After storage in 37 degrees C water for 24 hours, all specimens were thermocycled between 5 degrees C and 55 degrees C for 500 cycles with a 30-second dwell time, followed by immersion in 0.2% basic fucsine for 24 hours. Teeth were then embedded in cold cure acrylic resin, sectioned longitudinally, and the dye penetration at the enamel and cementum margins were scored at 30x magnification. Evaluations were rated from 0 to 3 (0 = no leakage; 1 = dye penetration up to one-half of the preparation depth; 2 = dye penetration more than one-half preparation depth, but less than the axial wall; 3 = dye penetration along the axial wall). Both F-2000 and Dyract-AP indicated no leakage in the enamel margins. Dyract-AP showed no leakage at either the enamel or dentin margins. Fisher's Exact Test revealed that this difference in dentin margins was statistically significant (p < 0.05). Under the given conditions, Dyract-AP and F-2000 demonstrated resistance to microleakage in enamel, and showed Dyract-AP to be more resistant to microleakage in dentin than F-2000.     

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.     

Influence of selective caries excavation on marginal penetration of class II composite restorations in vitro

Selective caries excavation may support pulp preservation. This in vitro study investigated the influence of selective removal of demineralized dentin on marginal integrity of composite restorations as determined by dye penetration. Dentinal caries-like lesions were produced in the approximal surfaces of 40 extracted human molars (ethylenediaminetetraacetate, 0.5 M, 96 h). The following test procedures were established: complete excavation, selective excavation, and caries-free control. Two class II cavities with enamel at the cervical margins were prepared per tooth and demineralization volume was determined by micro-computed tomography for the purpose of a stratified distribution to receive complete excavation or selective excavation. After complete or selective excavation (30 cavities each), adhesive composite restorations were placed. Cavities without demineralized dentin (20 cavities) served as control. The marginal integrity of restorations was evaluated by dye penetration with and without thermocycling or mechanical loading. Results were analyzed by non-parametrical statistical tests (Mann-Whitney U Test) with an α = 0.05 level of significance. Dye penetration did not differ significantly among completely excavated, selectively excavated, or undemineralized teeth, but was increased by thermocycling and mechanical loading in all experimental groups. Selective caries removal did not increase marginal penetration in class II restorations. The presence of remaining demineralized dentin surrounded by sound dentin did not impair marginal integrity of restorations with margins placed in sound enamel.     

Effect of elastic cavity wall and occlusal loading on microleakage and dentin bond strength

OBJECTIVE: This study evaluated the effect of an unfilled-adhesive resin (Adper Single Bond) and a filled-adhesive resin (Adper Single Bond 2) with and without a low viscosity resin (Filtek Flow) as an elastic cavity wall on marginal leakage and dentin microtensile bond strength in Class V composite restorations under unloaded and loaded conditions. METHODS: V-shaped cavities were prepared on the buccal surfaces of 56 premolars lined with unfilled (Groups 1 and 3) or filled (Groups 2 and 4) adhesives with (Groups 3 and 4) and without (Groups 1 and 2) a low viscosity resin and restored with a resin composite. The restored teeth in each group were divided into two sub-groups for unloaded and loaded conditions with 50N loading force for 250,000 cycles parallel to the long-axis of the tooth. Five specimens from each group were cut bucco-lingually 0.7 mm thick and subjected to a dye leakage test for four hours using 2% methylene blue dye. The tested specimens were then trimmed into dumbbell shapes at the gingival margin and subjected to microtensile testing. The remaining two specimens were cut, embedded and observed for resin/dentin interfaces under a scanning electron microscope. RESULTS: For the microleakage test, there were no significant differences in microleakage among the groups on both the enamel and dentin margin. No statistically significant differences were found between microleakage of the loaded and unloaded groups on enamel margins for all materials. There were statistically significant differences between microleakage of the loaded and unloaded groups on the dentin margin for Groups 3 and 4. For the microtensile test, the significant difference was found between Groups 1 and 4 for the unloaded groups. For the loaded groups, there were no significant differences between Groups 1 and 2 and Groups 3 and 4. There were no statistically significant differences in microtensile bond strength between the loaded and unloaded groups except for Group 2. CONCLUSION: The application of filled adhesive or low viscosity resin had no influence on marginal leakage at both the enamel and dentin margin but it had an influence on the microtensile bond strength to dentin of Class V restorations. Occlusal loading significantly increased the degree of marginal leakage at the dentin margin when low viscosity was applied in combination with either unfilled or filled-adhesives, but it decreased dentin bond strength in the group treated with only filled adhesive.     

Influence of resin composite shade and location of the gingival margin on the microleakage of posterior restorations

OBJECTIVE: The objective of this in vitro study was to evaluate the influence of resin composite shade and location of the gingival margin (enamel or dentin) on the microleakage of proximal restorations on posterior teeth. Methods and MATERIALS: Sixty freshly extracted human third molars were prepared with standardized Class II box-shaped cavities with proportional size and shape, with distal gingival margins located on the enamel and mesial gingival margins on dentin. The teeth were randomly divided into 6 groups according to resin shade (n=10): G1-Incisal; G2-A1; G3-A2; G4-A3; G5-A3.5; G6-A4. The cavities were restored with a total-etch 1-bottle adhesive system and microhybrid resin composites inserted in 4 increments, light cured for 20 seconds through the occlusal surface, then an additional 60 seconds for each surface. After 1 week of immersion in distilled water, the specimens were thermocycled (500 cycles, 5 degrees -55 degrees C, 30 seconds dwell time), sealed with nail polish and immersed in 0.5% basic fuschin solution for 24 hours. The restorations were sectioned longitudinally, and microleakage was evaluated using a 0-3 score scale. RESULTS: Data were subjected to Kruskal-Wallis and Wilcoxon tests at p<0.05. No statistically significant differences between groups were observed regarding the shade of resin composite (p=0.8570). When margins (enamel or dentin) were considered separately, statistically significant differences were observed between groups (p<0.0001), with enamel margins exhibiting lower degrees of microleakage. CONCLUSION: The variation of resin composite shades utilized in this study did not influence the microleakage of Class II restorations. However, the location of the gingival margin influenced the microleakage.     

A new method for sealing composite resin contraction gaps in lined cavities

Composite resin restorations are often applied in cavities where cervical margins are left unetched, resulting in poorer adaptation in this area. Recent experiments have indicated the possibility of impregnating with resin the gap caused by polymerization contraction. Cavities were prepared in vitro and in vivo. A thin liner was applied inside and outside the cavity. Except for the cervical wall, enamel margins were bevelled and acid-etched, and the cavities restored with Concise Enamel Bond and Composite. In another series, cavities with unetched enamel were restored. Since the liner was placed outside the cavity margins, excess material could be removed without blockage of the air-filled gap. Enamel Bond with a fluorescent additive was applied to various margins. Ground sections were prepared, and the penetration of this resin into the gap was examined with a microscope. In most teeth, the resin penetrated from 0.5 to 2 mm from the cervical margins. Similar penetration was seen from unetched margins, except for the occlusal one. No penetration was seen at acid-etched margins. By impregnating gaps with low-viscous resin after the filling has cured, one can obtain an improved seal at unetched margins.     

Prevention of microleakage into experimental cavities in teeth: an in vitro study

Dye penetration into cylindrical, 1 mm diameter cavities in forty-nine extracted human teeth was studied. Twenty-eight teeth were filled with Cavit-W or gutta percha and the remainder were left unfilled. The enamel surrounding all cavities was etched and the cavities sealed with three types of sealants. After 8 weeks, during which the temperature of the teeth was changed twice daily, Estilux appeared to have prevented the dye from penetrating into the cavities.     

Effect of new generation surface sealants on the marginal permeability of Class V resin composite restorations

This study evaluated, in vitro, the effectiveness of 5 surface sealants (Biscover, Optiguard, Seal-n-Shine, PermaSeal and DuraFinish); 1 pit and fissure sealant (Helioseal) and 1 dentin bonding agent (Adper Scotchbond MultiPurpose Adhesive) on the marginal sealing ability of Class V hybrid resin composite (Esthet.X) restorations. Ninety-six non-carious human molars were randomly assigned to 8 groups (n=12). Class V cavities were prepared on either the facial or lingual surfaces, with coronal margins in enamel and apical margins in cementum (dentin), and restored following manufacturers' instructions. Following finishing and polishing procedures, the covering agents were applied to each restoration and adjacent tooth surface, except for the control group restorations, which were not sealed. The teeth were thermocycled, immersed in a 1% methylene blue dye solution, sectioned and analyzed for dye penetration (leakage) using a 20x binocular microscope. Microleakage was evaluated at the coronal and apical margins using an 0-3 ordinal grading scale. Non-parametric data was analyzed at a p< or =0.05 level of significance. The Kruskal-Wallis test showed a significant difference was exhibited among groups at the coronal margins, with Helioseal pit/fissure sealant and DuraFinish surface sealant exhibiting significantly less leakage than the control and Adper Scotchbond MultiPurpose adhesive. At the apical margins, DuraFinish surface sealant showed significantly less leakage than the Biscover, Seal-n-Shine and PermaSeal surface sealants or Helioseal pit/fissure sealant, Adper Scotchbond MultiPurpose adhesive and the control group. According to the Wicoxon signed-rank test, significantly greater leakage was revealed at the apical margins compared to the enamel margins of the material groups.     

Marginal leakage of impregnated Class 2 composites in primary molars: an in vivo study.

In vivo impregnation of the cervical margin was used in an attempt to prevent leakage of class 2 composite restorations in primary molars. Examination after 18 months demonstrated clinical success of the restorations. However, the exfoliated teeth presented extensive dye penetration at the approximal margins of the restorations, suggesting that impregnation did not prevent marginal leakage.     

Effect of composite resin placement and use of an unfilled resin on the microleakage of two dentin bonding agents

The purpose of this study was to assess, in vitro, the microleakage of Class V restorations using two third generations dentin bonding agents, with a hybrid light polymerized composite resin. One of the bonding agents was of the NPG-PMDM type and the other was a polyhexanide. Restorations were placed in cavities prepared in extracted human premolars using either a bulk or incremental packing technique. The NPG-PMDM-based agent was used with and without an intermediary unfilled resin. The teeth were stored for 1 week at 37 degrees C, thermocycled for 1500 cycles between 55 degrees C, 37 degrees C and 5 degrees C and the restorations examined for leakage using methylene blue dye. The teeth were sectioned through the restorations and the degree of microleakage assessed visually. All groups of restorations showed some degree of leakage at the gingival margin. Statistical analysis showed that there were significant differences in the amounts of leakage (P less than 0.001). There was no difference in leakage between any of the groups that had been restored using the NPG-PMDM system (P greater than 0.05). There was, however, less leakage of the incrementally filled group compared with the bulk-packed group with the polyhexanide agent (P less than 0.05). When the two bonding agents were compared, there was no significant difference in leakage (P greater than 0.05) except for the incrementally-packed polyhexanide and the incrementally-packed NPG-PMDM with unfilled resin (P less than 0.05). Only one specimen in any of the groups leaked at the enamel margin.     

Marginal adaptation of heat-pressed glass-ceramic veneers to Class 3 composite restorations in vitro

The aim of the present in vitro study was to compare the marginal adaptation and integrity of heat-pressed glass-ceramic veneers to adjacent class 3 composite restorations and to enamel using four dual-curing composite resin cements of different viscosity with their corresponding dentin bonding agents. Thirty-six caries-free human maxillary incisors were first restored with mesial and distal class 3 composite restorations and then prepared for facial ceramic veneers. The cavity margins of the veneers were located either in the class 3 composite restorations or in the residual enamel. Heat-pressed glass-ceramic veneers (IPS Empress) were inserted adhesively using one of the following four luting systems in nine teeth: SonoCem (SC) with EBS; Variolink Ultra (VU), Variolink High-Viscosity (VHV), and Variolink Low-Viscosity (VLV) with Syntac. The veneer margins in the region of the composite restoration and in the region apical to the composite restoration (ceramic/composite resin cement interfaces, composite resin cement/composite restoration interface, and composite resin cement/enamel interface) were evaluated before and after thermo-cycling and mechanical loading (TCML) by quantitative margin analysis under a scanning electron microscope (SEM) using an image analysis system. Furthermore, microleakage was assessed in each tooth by dye penetration after TCML. For all luting systems, SEM analysis revealed excellent marginal adaptation of the ceramic veneers to the composite restorations as well as to enamel. The median percentages of marginal gap formation were 1.1% and less before TCML and 5.1% and less after TCML. The error-rates method revealed no statistical influence of the interface or of the viscosity of the luting material. Maximal values of dye penetration showed a significantly higher microleakage at veneers cemented with VU (median: 86.4%) compared to SC (median: 13.3%). In conclusion, the present data demonstrated that existing clinically acceptable class 3 composite restorations have no negative influence on the marginal adaptation of ceramic veneers. This was valid independent of the viscosity of the dual-curing composite resin cement when SC, VHV, or VLV was used.     

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     

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.     

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.     

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.     

In vitro comparison of marginal adaptation of various filling materials. I. Effect of the filling material on marginal adaptation

In a two-month in vitro experiment cervical marginal adaptation was examined in relation to the preparation, filling method and restorative material. Fifty Class II cavities were prepared in fifty extracted sound human premolar and molar teeth extending to the approximal cement-enamel junction. The cavities to receive composite restorations were bevelled at the vestibulo-occlusal and -approximal enamel margins, the other aspects of the cavity enamel and gingival margins at the cement-enamel junction being prepared conventionally. The cavities for amalgam were prepared and filled conventionally. The specimens were cycled in different buffer solutions and temperature, modelling possible variations in the oral environment and examined with SEM. The results were analysed using ANOVA. The best marginal adaptation among the composites was achieved with Charisma, Estilux Posterior, Durafil and Prisma AP. H at the bevelled enamel margins, the worst marginal fit was with Heliomolar and Polofil. It was concluded, that adhesive technique reduces, but does not eliminate marginal leakage.