Human pulp response to resin cements used to bond inlay restorations.

OBJECTIVE: The aim of this study was to evaluate the pulp response following cementation of inlays using two different resin cements. METHODS: Deep Class V cavities were prepared on the buccal surface of 34 sound human premolars. Impressions were taken and inlays were prepared which were cemented with the following luting materials-Group 1: Rely X Unicem (3M ESPE); Group 2: Variolink II (Ivoclar Vivadent). In Group 3 (control), after lining the cavity floor with Dycal (Dentsply Caulk) the inlays were cemented with Rely X Unicem. Four additional teeth were used as an intact control group. For Variolink II, the adhesive system Excite was used as part of the cementation procedure. After 7 or 60 days, the teeth were extracted and processed for histological assessment. RESULTS: At 7 days, Rely X Unicem and Variolink II system triggered in two samples a mild and moderate inflammatory response, respectively. At 60 days, the pulpal response decreased for both groups. A discrete persistent inflammatory response occurred in Group 2 in which displacement of resin components across the dentin tubules was observed. In the control group, normal histological characteristics were observed. The inflammatory response and tissue disorganization were related to the remaining dentin thickness between the cavity floor and the pulp tissue. SIGNIFICANCE: Techniques for inlay cementation using distinct luting cements may cause specific pulpal damage. Variolink II associated with the adhesive system Excite cause more aggressive effects to the pulp-dentin complex than Rely X Unicem cement when both are used to cement inlay restorations.     

The marginal quality of luted ceramic inserts in bovine teeth and ceramic inlays in extracted molars after occlusal loading

PURPOSE: To compare the marginal adaptation of adhesively luted ceramic inserts in standardized cylindrical cavities of bovine dentin and enamel with the marginal adaptation of adhesively luted ceramic inlays in extracted molars after mechanical loading, and to calculate the minimum sample size required to differentiate between material groups based on the findings of this investigation. MATERIALS AND METHODS: Ceramic inserts of similar dimension were luted in standardized cylindrical cavities of bovine dentin and enamel (n = 6, O = 4 mm) with seven different adhesive/resin cement systems (Syntac/Variolink, Prime & Bond NT/Variolink, Excite DSC/Variolink, AdheSE/Variolink, Excite DSC/Multilink, Multilink Primer/ Multilink, RelyX Unicem). The same materials were used to lute ceramic inlays (Empress II) in three-surface cavities of extracted human molars (n = 6 per group). All specimens were submitted to 2000 cycles of thermocycling. In addition, restored teeth were submitted to cyclic loading (640,000 cycles, 50 N) in a chewing simulator. Replicas after stressing were analyzed with SEM, and the percentage of continuous margin of the inserts and the inlays was calculated, differentiating the proximal part of the inlay into cervical dentin/enamel and axio-proximal enamel. The mean percentage values per material group of the insert and inlay groups were ranked using relative ranks. Sample size estimation was done for pooled standard deviations comparing between two and seven materials and assuming 20% or 10% of the mean of continuous margin to be statistically significant. RESULTS: The Spearman correlation coefficient between the variables "insert dentin" and "inlay cervical dentin" was 0.71 (p = 0.07), between "insert enamel" and "inlay axio-proximal enamel" 0.07 (p = 0.9). The variability of the test results was large for both the insert and inlay variables, especially at the resin-dentin interface. No statistically significant difference between the materials could be found for the insert method when ANOVA and Bonferroni post-hoc tests were applied (p > 0.05), while the inlays luted with Prime & Bond NT/Variolink showed significantly less continuous margin at the cervical dentin than all other groups with the exception of RelyX Unicem. At least 16 (63) inlays and 14 (57) inserts had to be used per group for differences of 20% (10%) of the mean of continuous margin. CONCLUSION: To evaluate luting agents with regard to their ability to reduce marginal discrepancies, the inlay model is inadequate due to high sample numbers which make the test time-consuming and expensive; furthermore its clinical relevance is uncertain. Alternatively, the insert method may be a suitable screening method for dentinal margins, although its clinical relevance is also unknown.     

两种树脂粘接剂粘接K2O-Al2O3-SiO2系统牙科玻璃陶瓷Ⅴ类洞嵌体的效果比较

目的评价2种树脂粘接剂与K2O-Al2O3-SiO2系统牙科玻璃陶瓷嵌体的粘接效果。方法24颗离体牙随机分为自固化组和双固化组,每组12颗,均预备Ⅴ类洞,分别使用自固化型树脂粘接剂和双重固化型树脂粘接剂粘接K2O-Al2O3-SiO2系统牙科玻璃陶瓷嵌体,热循环300次后浸入林格溶液待用。每组随机抽取6个样本,浸入品红溶液24 h后测量洞壁的染色渗透度。3个月后扫描电镜下观察余下6个样本粘接剂的丧失情况。结果自固化组粘接剂-牙体界面的染色渗透度小于双固化组（χ2=5.383,P=0.02）,粘接剂裂隙量小于双固化组（t=4.24,P〈0.001）。双固化组个别样本在陶瓷-粘接剂界面和粘接剂-牙体界面均出现粘接剂裂隙量较大的区域。结论自固化型树脂粘接剂粘接K2O-Al2O3-SiO2系统牙科玻璃陶瓷Ⅴ类洞嵌体的效果优于双重固化型树脂粘接剂。     

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.     

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.     

Luting of ceramic inlays in vitro: marginal quality of self-etch and etch-and-rinse adhesives versus self-etch cements.

OBJECTIVES: To evaluate marginal integrity of IPS Empress inlays luted with different adhesives and cements before and after thermo-mechanical loading (TML). METHODS: MOD cavities with one proximal box beneath the cementoenamel junction were prepared in 72 extracted human third molars. IPS Empress inlays were luted with nine combinations of adhesive and luting composite or self-etch cement alone (n=8): Prime&Bond NT Dual-Cure+Calibra (PC), XP BOND/SCA+Calibra (XC), XP BOND/SCA light-cured+Calibra (XL), Syntac+Variolink II (SV), Multilink Primer+Multilink (ML), AdhesSE DC+Variolink II (AV), ED Primer+Panavia F 2.0 (EP), RelyX Unicem (RU), and Maxcem (MC). Marginal quality was analyzed under an SEM using epoxy resin replicas before and after thermo-mechanical loading (100,000x50N and 2500 thermocylces between +5 and +55 degrees C). RESULTS: All systems involving the etch-and-rinse approach resulted in significantly higher percentages of gap-free margins in enamel than all other luting systems (p<0.05). ML and AV achieved higher percentages of gap-free margins in enamel than EP and RU (p<0.05), with EP and RU being significantly above MC (p<0.05). For dentine margins, XP Bond resulted in significantly higher percentages of gap-free margins than Prime&Bond NT, independent of a separate light-curing step (p<0.05). Between the luting systems XC, XL, SV, ML, AV, ED, EP, and RU, no significant differences were computed (p>0.05). MC ranged at the end of the statistical subsets with 62% gap-free margins (p<0.05; Mann-Whitney U-test). SIGNIFICANCES: Etch-and-rinse adhesives combined with conventional luting resin composites reveal still the best prognosis for adhesive luting of glass ceramic inlays.     

Shear bond strength of tooth-colored indirect restorations bonded to coronal and cervical enamel

This study evaluated the shear bond strength of resin inlays bonded with resin cement to cervical and mid-coronal enamel. Two regions of enamel, cervical and mid-coronal, were chosen from the buccal surface of extracted molars. Composite "inlays" (Estenia, Kuraray Medical Inc) were fabricated indirectly and cemented with a dual-cured resin cement (Panavia Fluoro Cement II, Kuraray Medical Inc). The resin cement was cured with or without light irradiation for 30 seconds. After 24-hours or one-week's storage in 37 degrees C water, the bonded inlays were subjected to a microshear bond test, whereby a shear force was applied to the inlays at a crosshead speed of 1 mm/minute. The data were statistically analyzed using ANOVA and Fisher's PLSD test, with significance defined as p<0.05. Observations using confocal laser scanning microscopy were also performed after debonding the specimens. The light-cure method showed significantly higher bond strengths to both enamel regions compared with self-cure, especially at 24 hours (p<0.05). However, bond strength of the self-cured resin cement significantly improved after one week's storage (p<0.05; cervical enamel: p=0.022, midcoronal enamel: p=0.0024). The cervical enamel showed significantly lower bonding than midcoronal enamel (p<0.05), except for the self-cured specimens at 24 hours. Light curing of resin cement is a better choice than self-curing for luting of indirect restorations. The bond strength of indirect restorations to cervical enamel was lower than mid-coronal enamel.     

Microleakage of indirect composite inlays

The purpose of this in vitro study was to evaluate the microleakage of indirect composite inlays and to compare leakage of inlays with directly placed composite restorations. Standardized MOD preparations were cut in 50 extracted human molars. One gingival margin was placed in enamel above the CEJ, and the other was placed in dentin below the CEJ. Two groups of teeth were directly filled with composites (P-30 and Heliomolar) after being etched, and dentin bonding agents were applied. Two groups of teeth were restored with composite inlays that were fabricated on stone dies. The inlays were made and luted with the same two composites. The last group of teeth was restored with Heliomolar inlays luted with Dual cement. The specimens were thermocycled 300 times between 5 and 50 degrees C. Microleakage was evaluated by use of the silver-nitrate staining technique. The depth of leakage was measured microscopically after the teeth were sectioned. Both direct restorations and inlays showed substantial leakage at gingival-dentin margins; however, there was only superficial leakage at enamel margins. P-30 inlays and Heliomolar inlays cemented with Dual leaked less than direct restorations at the gingival-dentin margins. There was no difference in leakage of enamel margins of inlays and direct restorations, except that direct Heliomolar restorations leaked more than the others. There was no difference in leakage between Heliomolar restorations luted with light-cured or dual-cured cement.     

Comparison of microleakage of three acid-base luting cements versus one resin-bonded cement for Class V direct composite inlays

STATEMENT OF PROBLEM: Demineralized dentin beneath set cement may adversely affect microleakage under fixed restorations. PURPOSE: Microleakage of direct composite inlays cemented with acid-base cements and a methyl methacrylate resin cement were evaluated to determine their effect on the integrity of the underlying hybridized dentin. MATERIALS AND METHODS: Sixty Class V box preparations (3 mm x 3 mm x 1.5 mm) were precisely prepared in previously frozen bovine teeth with one margin in enamel and another margin in dentin. Direct composite inlays (EPIC-TMPT) for each preparation were divided into 4 groups of 15 specimens each and cemented with 3 acid-base cements (control group): Elite, Ketac-Cem, Hy-Bond Carbo-Cem, and 1 adhesive resin cement: C&B Metabond. All specimens were stored in distilled water for 24 hours at 37 degrees C before immersion in 0.5% basic fuchsin for 24 hours. The dye penetration was measured on the sectioned specimens at the tooth-cement interface of enamel and cementum margins and recorded with graded criteria under light microscopy (Olympus Vanox-T) at original magnification x 50, 100, and 200. A Kruskal-Wallis and the Mann-Whitney test at P<.05 were used to analyze leakage score. RESULTS: All cementum margins of the 3 acid-base cements tested demonstrated significantly higher leakage scores than cementum margins for inlays cemented with the resin cement tested(P<.01). No leakage along the tooth-cement interface was found for inlays retained with the adhesive resin cement. CONCLUSIONS: Within the limitations of this study, the 3 acid-base cements tested exhibited greater microleakage at the cementum margins than did the adhesive resin cement that was tested.     

The effect of eugenol-containing and eugenol-free temporary cements on microleakage in resin bonded restorations.

Eugenol is known to have a detrimental effect on both composite resin and dentin bonding agents. The purpose of this in vitro investigation was to compare the microleakage among groups of resin-luted inlays when the cavity preparations were pretreated with a eugenol-containing temporary cement, a eugenol-free temporary cement, or no temporary cement. Class 5 inlay preparations (20 per group) were completed in extracted human molars. Following the fabrication of composite resin inlays, the preparations were filled with either a eugenol-based temporary cement, a eugenol-free temporary cement, or no cement. After removal of the cement from the cavity preparations and application of a dentin bonding agent, the composite inlays were luted with a resin cement, thermocycled, stained, sectioned, and evaluated for microleakage under a stereomicroscope. None of the groups exhibited significant leakage at the enamel margins. Both of the groups treated with temporary cement leaked at the nonenamel margins significantly more than the control (no cement) group. No significant difference in leakage was demonstrated between the groups treated with the eugenol-containing and the eugenol-free temporary cements.     

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.     

Clinical evaluation of light-cured composite resin inlays in primary molars

A study was carried out to evaluate the clinical potential of a visible light-cured composite resin inlay (P-30) cemented with an adhesive resin cement (Panavia-EX) in primary molars. The inlays were placed in Class I complex, Class II MO, DO, MOD and more extensive cavity preparations in primary molars. Fifty restorations were placed in 40 patients and evaluated at baseline, 3 months, 6 months, 1 year and 2 years. The evaluations were carried out according to the U.S. Public Health Service Clinical Rating System. The results showed the composite resin inlay cemented with an adhesive resin cement to be a highly effective combination.     

Resin-modified glass ionomer cement and self-cured resin composite luted ceramic inlays. A 5-year clinical evaluation.

OBJECTIVE: This study evaluated IPS Empress ceramic inlays luted with two chemical-cured luting agents, a resin-modified glass ionomer cement (Fuji Plus (F)) and a resin composite (RC) (Panavia 21 (P)). METHODS: Seventy-nine ceramic inlays were placed in Class II cavities in 29 patients. At least two inlays were placed in each patient to compare the luting techniques intra-individually. In each patient half of the inlays were luted with F and the other half with P. The inlays were evaluated clinically, according to modified USPHS criteria (van Dijken, 1986), at baseline, after 6 months, and yearly during 5 years. RESULTS: At 5 years, 71 inlays were evaluated. Two small partial fractures were observed at 3 years (1P, 1F). One inlay showed recurrent root caries at 4 years (P). Four inlays, two in each group showed non-acceptable color match (2P, 2F). Small defects were observed in 4 inlays (2P, 2F). A slight ditching of the cement margins was observed in both luting groups but did not seem to increase during the second half of the evaluation. No significant difference in durability was observed between the two luting agents. SIGNIFICANCE: IPS Empress inlays luted with the chemical-cured RC and the resin-modified glass ionomer cement functioned satisfactory during the 5 years follow-up.     

Effect of dentin adhesives used as sealers and provisional cementation on bond strength of a resin cement to dentin

PURPOSE: To evaluate the effects of dentin adhesives employed as resin sealers and provisional cementation on the bond strengths of a resin cement to dentin. METHODS: A two-step etch-and-rinse adhesive (Excite DSC--Group 1) and two-step self-etch adhesive (AdheSE--Group 2) were applied to exposed dentin surfaces prepared from human molars (N=4). Water was used instead of a resin sealer in control Groups 3 and 4. A eugenol-free provisional cement (except for Group 4) was applied to the treated surfaces. After storing in distilled water for 1 week, the provisional cement was removed and cylindrical composite blocks were luted with a resin cement (Variolink II). 0.9 x 0.9 mm sticks were produced from these luted specimens for microtensile bond testing and SEM examination. RESULTS: One-way ANOVA revealed that neither the resin sealer nor the temporary eugenol-free cement had a negative effect on the final bond strength (P> 0.05). Mixed failures were predominantly identified from SEM.     

Clinical performance of pressed ceramic inlays luted with resin-modified glass ionomer and autopolymerizing resin composite cements

STATEMENT OF PROBLEM: Several in vitro studies have been published showing the incapability of the chemical cure of dual-cured resin composite luting agents to compensate for absence of visible light activation. PURPOSE: This study evaluated and compared pairs of Empress ceramic inlays luted with 2 chemical-cured luting agents: a resin-modified glass ionomer cement and a resin composite within individual patients. MATERIAL AND METHODS: Seventy-nine ceramic inlays were placed in class II cavities in 29 patients. In each patient half of the inlays were luted with a resin-modified glass ionomer cement and the other half with a chemical-cured resin composite cement. The inlays were evaluated clinically, according to modified USPHS criteria, at baseline, after 6 months, and 1 and 2 years. RESULTS: No failed inlays were observed during the 2-year follow-up. A slight ditching of the cement margins was observed in both luting groups. No significant difference was seen between the 2 luting techniques. CONCLUSION: IPS Empress inlays luted with both chemical-cured luting agents functioned satisfactorily in the short-term follow-up. Longer observation periods are necessary to evaluate the long-term clinical behavior of both luting techniques.     

In vivo and in vitro evaluation of marginal fit of class II ceromer inlays

The aim of this study was to evaluate the marginal adaptation of class II ceromer (Targis, Vivadent) indirect inlay restorations under both in vivo and in vitro conditions. Twenty Targis inlays were produced for class II inlay cavities (13 mandibular and seven maxillary teeth) in 20 patients. The in vivo adaptation of the inlay to the tooth cavity was evaluated by means of silicone replica technique. For in vitro evaluation, 20 mesio-occluso-distal (MOD) Targis inlays were made in extracted upper molars. Half of the inlays were cemented with Variolink high-viscosity resin cement while the other half was cemented with Variolink Ultra. The replica specimens and in vitro samples were sectioned buccolingually and mesiodistally, and marginal adaptation was evaluated at both proximal and occlusal margins at 200x magnification under a light microscope. The data was analyzed with anova (P < 0.05). The in vivo mean film thickness values for occlusal and proximal locations were recorded as 73 and 132 microm respectively. In vitro mean marginal fit values were observed as 48 and 67 microm for occlusal and proximal margins of inlays luted with Variolink II high viscosity. The marginal fit values recorded under in vivo conditions were higher in magnitude than the measurements obtained under in vitro conditions. The use of a highly filled resin luting agent with an ultrasonic insertion technique did not cause an increase in marginal gap width of the inlay.     

The leakage of Class II cavities restored with packable resin-based composites

Recently, new resin-based composites, called "packable" or "condensable" resin composites, are being promoted as amalgam alternatives. The purpose of this study was to evaluate leakage in Class II cavities restored with the five packable resin-based composites. On 45 freshly extracted human molars, cavities were prepared following a standardized pattern in which the Class II cavity had a length of 3.0 mm, width of 2.0 mm, and depth of 1.5 mm occlusally. The proximal box had an axial depth of 1.5 mm and a buccolingual width of 4.0 mm. The cervical margin was located 1.0 mm below the cement enamel junction (CEJ). The teeth were randomly divided into five groups of 8 each. The cavity surface was conditioned with 36% phosphoric acid, rinsed, excess water removed, and a dental bonding adhesive (Prime&Bond NT) was used for all the cavities. The teeth were then restored according to the manufacturer's instructions: Group 1, Surefil; Group 2, Solitaire; Group 3, Alert; Group 4, Filtek P60; and Group 5, Prodigy Condensable. After the restorations were completed, the specimens were finished and polished with an aluminum-oxide-coated disc, thermocycled, stained, sectioned, and viewed under a stereomicroscope for leakage at occlusal/enamel and gingival/dentin margins. All test groups showed that leakage of gingival/dentin margins were greater when compared with leakage of occlusal/enamel margins. At the occlusal/enamel margins, there were no significant differences between the materials; however, at gingival/dentin margins, Filtek P60 and Prodigy Condensable demonstrated less leakage, while Solitaire demonstrated greater leakage.     

In vitro evaluation of microleakage of indirect composite inlays cemented with four luting agents

STATEMENT OF PROBLEM: Microleakage around dental restorations is implicated in the occurrence of secondary carious lesions, adverse pulpal response, and reduced restoration longevity. PURPOSE: The aim of this in vitro study was to evaluate the microleakage of indirect resin composite inlays cemented with 4 luting agents. MATERIAL AND METHODS: Standardized Class V inlay preparations overlapping the cemento-enamel junction were prepared on the buccal and lingual surfaces of 40 extracted human mandibular third molars. Eighty postpolymerized, heat-treated resin composite inlays (Targis, 72 specimens, 8 controls) were processed in stone replicas and cemented into the preparations using 4 luting agents (n = 18 + 2 controls for each cement group): a resin composite used with a bonding agent (Variolink II/Excite), a resin composite used with a self-etching primer, but without bonding agent (Panavia F/ED Primer), a modified resin composite used with a bonding agent (Resinomer/One Step), and a resin-modified glass-ionomer cement (Fuji Plus). Thirty-six inlays (n = 9 + 1 control) were subjected to thermal cycling (2000 cycles, 5 degrees C/55 degrees C), whereas the other 36 were not. All the teeth were then immersed in 1% methylene blue dye solution for 48 hours. Microleakage score, margin location (enamel/cementum), thermal cycling history, and preparation location (buccal/lingual) were analyzed using a multivariate model (alpha = .05). Multivariate analysis was performed using a polychotomous logistic regression. RESULTS: The preparation location had no significant effect on dye penetration. The margin location (enamel or cementum) and the thermal cycling had a significant effect on microleakage (odds ratios [ORs] = 17.6 and 8.04, respectively). In comparing the 3 resin-based luting agents (Variolink II, Panavia F, and Resinomer) to Fuji Plus, Panavia F exhibited the lowest significant overall microleakage (OR = 0.09), followed by Variolink II (significant OR equal to 0.43), whereas Resinomer demonstrated the greatest significant overall microleakage (OR = 1.35). CONCLUSION: Within the experimental conditions of this in vitro study, thermal cycling significantly increased microleakage (OR = 8.04). The overall microleakage at the enamel margins was significantly lower than the overall microleakage at the cementum margins for the 4 luting agents tested (OR = 17.6).     

Bond strength of glass-ceramics on the fluorosed enamel surfaces

OBJECTIVES: Effect of different adhesive luting systems on the shear bond strength of IPS Empress 2 ceramic restorations to fluorosed enamel surface was investigated. METHODS: Forty-eight ceramic discs (2 mm x 3 mm; IPS Empress 2) were fabricated. Twenty-four non-carious extracted human molar teeth with fluorosis and 24 without fluorosis were cleaned with pumice using a plastic brush and then they were divided into two main groups. The IPS Empress 2 ceramic discs were luted to the teeth of four subgroups with two different adhesive luting systems, Variolink 2/Excite DSC (etch-and-rinse) and Clearfil Esthetic Cement/ED Primer II (self-etch), thermocycling was performed 5000 times. Shear bond strengths were tested using Shimadzu Universal Testing Machine until failure. An optical microscope and image analyzer were used at 10x and 1000x magnification to analyze the surfaces for adhesive, cohesive and mixed failure percentages. Data was analyzed with one-way ANOVA and Tukey test at a significance level of p<0.05. RESULTS: Mean shear bond strength data of the groups in MPa were; Variolink 2/Excite DSC on fluorosed enamel: 18.3+/-3.08, Variolink 2/Excite DSC on non-fluorosed enamel: 18.79+/-2.65, Clearfil Esthetic Cement/ED Primer II on fluorosed enamel: 8.43+/-2.45, Clearfil Esthetic Cement/ED Primer II on non-fluorosed enamel: 13.53+/-1.68. Mixed failure was the most prevalent type of failure in moderate fluorosed and non-fluorosed teeth with etch-and-rinse dentin bonding system, and in fluorosed teeth with self-etch dentin bonding system. CONCLUSIONS: The use of an etch-and-rinse adhesive luting procedure produced higher bond strengths of glass-ceramics bonded to fluorosed and non-fluorosed enamel surfaces than the self-etch bonding system.     

Influence of resin cement viscosity on microleakage of ceramic inlays.

OBJECTIVES: The aim of the present investigation was to evaluate the effect of the different viscosities of two resin luting cements on microleakage of ceramic inlays at dentinal margins. The effect of the width of the space between inlay and tooth, on the quality of the marginal seal was also investigated. METHODS: Mesial and distal class V cavities were prepared in 48 extracted third molars. The incisal margins of the cavities were in enamel and the cervical margins in dentin. Subsequently, Empress inlays with different cervical margin gap dimensions were fabricated. The mean cervical gap dimensions in the respective groups were as follows: group 1 (27 microm); group 2 (232 microm); group 3 (406 microm). Half the inlays in each group (16) were cemented with a low viscous resin luting cement, and half (16) with a highly viscous resin luting cement. The teeth were subjected to occlusal loading with synchronized thermal cycling in a masticatory simulator. Then, the specimens were immersed in basic fuchsin solution, and dye penetration along the cavity walls was measured. In addition, marginal adaptation was analyzed in the SEM at baseline and after loading, using a replica technique. RESULTS: With regard to dye penetration at dentinal margins, the highly viscous cement performed statistically significantly better at dentin/composite margins than the low viscous cement (p=0.0158). These findings are supported by SEM analysis. SIGNIFICANCE: It is assumed that polymerization stress within the luting cement could not be completely compensated for by larger luting spaces. Highly viscous luting cements are recommended for cementing class V inlays in larger luting spaces.