Preparation and filling of small oval root canals: influence of file system and sealer.

OBJECTIVE: To carry out a morphometric analysis of small oval root canals prepared with different instruments (part 1) and filled with different sealers (part 2). METHOD AND MATERIALS: Ninety extracted mandibular incisors with small oval root canals were instrumented with Self-Adjusting File (n = 45), XP-endo Finisher (n = 15), GentleFile (n = 15), or Reciproc (n = 15). All groups of part 1 were filled with AH Plus (n = 15 each). For part 2 (including group Self-Adjusting File/AH Plus) teeth instrumented with Self-Adjusting File were additionally filled with GuttaFlow Bioseal (n = 15) or Total Fill BC sealer (n = 15). All sealers were placed with a lentulo and filled with master point and additional points. Serial cuts were made at 1-mm intervals up to 10 mm. Total root canal area, percentage of gutta-percha filled area (PGFA), sealer, voids, and debris were evaluated using interactive image analysis software. RESULTS: Preparation with Reciproc caused significantly wider canals than with Self-Adjusting File, GentleFile, or XP-endo Finisher, but also resulted in the greatest PGFA and lowest percentage of sealer (P ≤ .05). Following XP-endo Finisher, the significantly greatest percentage of debris (30%) was found 1 mm from the apex (P ≤ .05). Regarding different sealers, only minor differences were found (GuttaFlow Bioseal: less percentage of sealer at 2 and 3 mm levels [P ≤ .05]). CONCLUSION: Within the limits of this study Reciproc caused the greatest substance loss, but also the most favorable PGFA. The apical debris accumulation with XP-endo Finisher needs further investigation. The sealers under investigation performed equally well.

Filling of small oval root canals: influence of sealer placement and filling technique.

Objectives: The aim of this study was to carry out a morphometric analysis of small oval root canals filled with GuttaFlow 2 sealer (Coltène/Whaledent) using different methods of sealer placement and different root canal filling techniques.
Method and materials: Eighty extracted mandibular incisors with small oval root canals were instrumented with the Self-Adjusting File (Redent Nova). GuttaFlow 2 was placed using a lentulo spiral, paper point, master point, or sonically activated CanalBrush (Coltène/Whaledent), followed by the placement of a master point and accessory points (M?P+) (part 1). GuttaFlow 2 was placed using a lentulo spiral without a gutta-percha point, together with a single point, with a chloroform-dipped master point, or the latter with accessory points (ChMP+) (part 2). Serial cuts were made at 1-mm intervals up to 10 mm. The percentages of gutta-percha filled area (PGFA), sealer, voids, and debris were evaluated using interactive image analysis software.
Results: For part 1 of the study (sealer placement), significant differences regarding PGFA at 2 and 5 mm from the apex were found, whereas for part 2 (filling technique), significant differences were found at all levels besides 2 and 4 mm (Kruskal-Wallis test, P = .05). ChMP+ reached 85% PGFA at 3 mm from the apex, but only 30% near the apex. The MP+ groups showed a relatively equal distribution of PGFA by 60% to 80% at different levels. GuttaFlow 2 without a gutta-percha point exhibited significantly more voids and debris than the other groups (Kruskal-Wallis test, P = .05).
Conclusion: Within the limits of this study, MP+ could be recommended for clinical use. The presence of voids and debris for the group without a gutta-percha point needs further investigation.

Temperature changes affect the rheological properties of a silicone-based and an epoxy resin-based root canal sealers.

To evaluate temperature changes on the rheological properties (setting time and complex viscosity (η*)) of GuttaFlow Bioseal (GFB) and AH Plus Jet (AHPJ). Rheological measurements were performed in oscillating mode at the strain amplitude and angular frequency of 0.01% and 10 rad s-1 , respectively. Each sealer (n = 5) was tested running a temperature ramp (rapid increase to 80°C, 1 min constantly at 80°C, and slower decrease to 37°C). Control groups (n = 5) were tested at a constant temperature of 37°C. Kolmogorov-Smirnov and one-way ANOVA (P < 0.05) statistical tests were performed. The temperature ramp reduced setting time of GFB (24.85 to 4.45 min) (P < 0.05), but did not alter that of AHPJ (P > 0.05). GFB exhibited an increased η*, whereas the AHPJ η* was decreased when heated (P < 0.05). Rheological properties of sealers were negatively affected by temperature changes.

Do Contaminating Substances Influence the Rheological Properties of Root Canal Sealers?

INTRODUCTION: This study evaluated the effect of residual substances derived from irrigant solutions and intracanal medications on the rheological properties of a silicone, gutta-percha, and bioactive glass-based sealer in comparison with an epoxy resin-based sealer. METHODS: Thin films of contaminants (0.5 µL) (3% sodium hypochlorite [NaOCl], chlorhexidine digluconate [CHX], 17% EDTA, calcium hydroxide, 40% citric acid, or distilled water [DW]) were applied along with freshly mixed GuttaFlow Bioseal (GFB; Coltene/Whaledent, Langenau, Germany) or AH Plus Jet (Dentsply DeTrey, Konstanz, Germany) on the lower plate of a dynamic rheometer. Rheological measurements were performed in oscillating mode at the strain amplitude, angular frequency, and constant temperature of 0.01%, 10 rad/s, and 37°C, respectively. Samples without contaminants served as controls. All measurements were performed 5 times. The Kolmogorov-Smirnov test and 1-way analysis of variance followed by the Student-Newman-Keuls test were performed to analyze the results (P < .05). RESULTS: The contaminants did not alter the setting time of GFB compared with the controls; however, CHX and calcium hydroxide decreased its complex viscosity (ƞ*) (P < .05). The setting time of AH Plus Jet was increased by DW, CHX, citric acid, and EDTA (P < .05). All contaminants decreased its ƞ* at the setting point (P < .05). NaOCl led to the greatest alteration of its rheological parameters. CONCLUSIONS: Irrigant solutions and intracanal medications adversely affected at least 1 of the tested rheological properties of both sealers, except for DW and 3% NaOCl, which did not alter any rheological property of GFB.

Removal of Radioactively Marked Calcium Hydroxide from the Root Canal: Influence of Volume of Irrigation and Activation.

INTRODUCTION: The purpose of this study was to evaluate the amount of calcium hydroxide (Ca[OH]2) removed by irrigation with different volumes and activation methods. METHODS: One hundred thirty extracted straight, single-rooted human teeth were instrumented to size 45/.04. One hundred twenty teeth were filled with radioactively marked Ca(OH)2 and a gutta-percha point; 10 teeth with only gutta-percha served as a negative control. All specimens were stored in saline solution (7 days at 35°C). After storage, teeth were randomly divided into 12 groups (n = 10). The gutta-percha was taken out, and Ca(OH)2 was removed either by irrigation with different volumes (0 mL, 0.5 mL, 1 mL, 2 mL, 4 mL, or 8 mL) or mechanical activation with a 2- or 4-mL volume using a file (Instr) (FlexMaster size 45/.04; VDW, Munich, Germany), a brush (CanalBrush [CB]; Coltène/Whaledent, Langenau, Germany), or passive ultrasonic irrigation (PUI, smooth wire). Irrigation was performed by alternating 40% citric acid and 3% sodium hypochlorite. Residual Ca(OH)2 was measured by scintillation and expressed as a percentage of the original Ca(OH)2. RESULTS: Increasing the irrigation volume led to a significant decrease (P < .05) of residual Ca(OH)2 (0 mL [98.5%], 0.5 mL [21.7%], 1 mL [16.5%], 2 mL [12.9%], 4 mL [8.7%], 8 mL [5.0%], and negative control [0.0%]). Activation led to less residual Ca(OH)2 (2 mL Instr [12.0%], 2 mL CB [11.7%], 2 mL PUI [9.1%], 4 mL Instr [8.5%], 4 mL CB [7.4%], and 4 mL PUI [6.2%]), with significant differences according to the PUI (P < .05). CONCLUSIONS: No irrigation procedure was able to remove Ca(OH)2 completely. PUI was the most effective activation method. However, irrigation with an 8-mL volume was the most effective.

Apical debris removal of CanalBrushes with different tip modifications.

OBJECTIVE: In this study the apical debris score regarding the rotary use of the CanalBrush (Coltène-Whaledent) with three different tip variations was compared to that of sole needle irrigation. METHOD AND MATERIALS: Sixty straight roots of human teeth with one canal were instrumented to size 45/.04. Roots were split into halves, reassembled, and embedded in model resin to form separable tooth models. Artificially manufactured dentin debris was packed into the apical 2 mm of the roots to form a relatively consistent debris challenge to be assessed. Then, the debris of each root half was evaluated apically using a modified Hülsmann-score under a light microscope. After remounting the models, root canals were irrigated with NaOCl 3% (2 mL): group 1 with sole needle irrigation, in groups 2 to 4 additionally agitated with different versions of the CanalBrush for 30 s at 600 rpm; group 2, one straight bristle ("old"); group 3, two additional diagonal bristles ("new"); group 4, central straight bristle of the new version removed ("experimental"). Following this, all root halves were reevaluated. RESULTS: Irrigation reduced debris scores in all groups (Wilcoxon tests, P < .001). Mean debris scores were reduced from a pre-irrigation score of about 4 for all groups to a score of around 2 to 3 in groups 1 and 2, and to scores around 1 in groups 3 and 4. Samples of groups 3 and 4 were significantly cleaner than of groups 1 and 2 (Mann-Whitney tests, P < .05). CONCLUSION: CanalBrushes with diagonal bristles achieved an improved apical cleaning ability.

Sealing ability of different versions of GuttaFlow2 in comparison to GuttaFlow and AH Plus

Introduction and objective: GuttaFlow2 is a further development of the silicone sealer GuttaFlow, exhibiting a stiffer consistency. This is intended to overcome possible problems regarding retention of the apical part of the root canal filling when preparing for a fiber post. GuttaFlow2 is delivered within a capsule, like GuttaFlow, or within an automix syringe. This study compared apical dye leakage of GuttaFlow2 in comparison to GuttaFlow and AH Plus. The null hypothesis tested was that different sealers exhibited similar microleakage. Material and methods: Seventy extracted human lower premolars with fully mature apices were root canal prepared to 45/.04 and divided into seven groups: group 1: AH Plus sealer, group 2: "normal" setting GuttaFlow, group 3: "fast" setting GuttaFlow, group 4: GuttaFlow2 within a capsule, group 5: GuttaFlow2 within an automix syringe, group 6: positive control, group 7: negative control (n = 10 each). Root canals were filled with sealer (except group 7) and a master gutta-percha cone size 40/.04 using the non-compaction technique. A dye penetration test was carried out by centrifugation for 3 min at 30 G within 5 % methylene blue dye. Linear dye penetration was recorded. Statistical evaluation was carried out with IBM SPSS 19.0 (α = 0.05). Results: The positive control was significantly different from all other groups (ANOVA, p < 0.001; Student-Newman-Keuls post-hoc test p < 0.05). When the control groups were disregarded, no significant differences were apparent. Groups 1 to 5 showed low leakage values when compared with results of earlier studies using a similar methodology. Conclusion: All sealers tested exhibited low dye leakage values.

pH neutralization and influence on mechanical strength in self-adhesive resin luting agents.

OBJECTIVE: The aim of this study was to evaluate if pH-neutralization behavior of self-adhesive resin cements has an influence on their mechanical properties. METHODS: pH-neutralization, water sorption, solubility and flexural strength of G-Cem Automix (GCA), G CEM Capsules (GCC), Maxcem Elite (MCE), RelyX Unicem Clicker (RXC), RelyX Unicem Maxicap (RXM), RelyX Unicem 2 (RX2), and Speed-Cem (SPC) were tested in self-curing mode. Specimen's pH-values were recorded up to 24h with a pH-electrode. Water sorption (WS) and solubility (SO) were measured. Flexural strength (FS) was evaluated before and after thermocycling (TC) and fracture surfaces analyzed under SEM. RESULTS: RX2 (pH(24) 5.89), RXC (pH(24) 5.49) and SPC (pH(24) 5.42) showed highest 24h pH-values, followed by GCA (pH(24) 5.34). Capsulated products and MCE (pH(24) 3.90) reached lower pH-values. GCC (75.78 µg/mm(3)) showed the highest WS followed by MX (69.64 µg/mm(3)), RXM (64.76 µg/mm(3)), GCA (25.86 µg/mm(3)) and SPC (30.42µg/mm(3)). Capsulated products RXM (56.58 µg/mm(3)) and GCC (30.94 µg/mm(3)) presented the highest SO, GCA (4.06 µg/mm(3)) and SPC (4.26 µg/mm(3)) revealed the lowest. GCA (114.03 MPa) had the highest initial FS followed by SPC (79.81 MPa), RXM (41.61 MPa) the lowest. FS of all materials decreased significantly after TC except for RXC (44.65 MPa) and RX2 (65.92 MPa). FS of GCC (16.47 MPa) and MCE (28.21 MPa) decayed the most. A highly linear correlation was observed between percentage decrease of FS after TC and 24h pH-values (R(2)=0.861). SIGNIFICANCE: Within the limits of this study pH-neutralization behavior has an influence on mechanical stability. When using self-adhesive resin luting agents, automix-syringe products with improved pH-neutralization behavior should be favored.

A novel approach for filling tunnel-prepared teeth with composites of two different consistencies: a case presentation.

A new approach to fill tunnel preparations with composites of two different consistencies is presented. Removal of caries through a narrow access space and reliably filling this cavity are the two main problems with tunnel-prepared teeth. Caries removal can be supplemented by the use of hand instruments, especially curettes, but filling the lesion with composite of a single consistency is problematic. Flowable composite alone does not create enough pressure to place the filling material into shallow extensions of the lesion; packable composite does not flow well enough. A solution for this problem may be a dual-consistency technique: flowable composite is placed, followed by packable composite, with no light curing in between. The flowable composite is pressed into small details of the cavity by the pressure created by the packable composite.

Seven-year clinical performance of CEREC-2 all-ceramic CAD/CAM restorations placed within deeply destroyed teeth.

OBJECTIVES: Adhesively luted all-ceramic restorations represent a promising way to preserve and stabilize weakened tooth substance, but little information is published about the clinical performance of extensive all-ceramic restorations. MATERIALS AND METHODS: A total of 78 large CEREC 2™ single-tooth all-ceramic restorations had been placed in 35 patients. After 7 years, 59 teeth in 25 patients were reevaluated according to USPHS or modified USPHS criteria regarding aesthetic properties, e.g., "anatomic form," "color match," and "marginal discoloration"; functional properties, e.g., "marginal integrity," wear expressed by the criteria "proximal contact" and "static/dynamic occlusal relationship"; and biological properties, e.g., "tooth vitality" and "secondary caries". Additionally, the "proportion of margin below/above cemento-enamel junction" was included. RESULTS: Two restorations had failed prior to the 7-year recall, one due to a bulk fracture of the restoration and one due to poor marginal integrity (rated "Charlie") after 4 years. Other six restorations were rated as failure at the 7-year evaluation (three restorations revealed secondary caries, one was bulk fracture of the Cerec 2 restoration, and two failures were related to endodontic problems resulting in extraction or amputation of one root, respectively), resulting in a failure rate of 13.1% after 7 years. A total of 96.4% of the restorations revealed sufficient ratings for esthetic properties "anatomic form," "color match," "marginal discoloration," and "marginal integrity". CONCLUSIONS: The survival rate of 86.9% at the 7-year recall demonstrates that adhesively luted all-ceramic CAD/CAM-generated restorations are suitable for restoration of extended coronal defects. CLINICAL RELEVANCE: CAD/CAM-generated all-ceramic restorations facilitate the reconstruction of deeply destroyed teeth irrespectively of the location of the cavity margins.

Bond strength of adhesive cements to root canal dentin tested with a novel pull-out approach.

INTRODUCTION: A novel approach to the pull-out test using silica-coated and silanized steel spreaders was designed to avoid influence from the post-cement interface. In this study, this test was applied to compare the post retention of adhesive versus conventional cements. METHODS: Canals of 90 single-rooted human teeth were prepared to size 60 taper .02; trimmed to an 8-mm root canal length; irrigated with 40% citric acid, 3% NaOCl, and 70% ethanol; and randomly divided into 9 groups (n = 10). Steel spreaders (size 55, taper .02) were silica coated and silanized with the Rocatec system (3M-Espe, Seefeld, Germany), except for a control group using GCem, and cemented with one of these adhesive luting materials (RelyX Unicem [3M-Espe], Clearfil SA Cement [Kuraray Medical, Okayama, Japan], Bifix SE [Voco GmbH, Cuxhaven, Germany], NX3 [Kerr, Orange, CA], GCem [GC Corp, Tokyo, Japan], or SmartCem2 [Dentsply De Trey GmbH, Konstanz, Germany]) or conventional cements (Hoffmann's cement [Hoffmann Dental Manufaktur GmbH, Berlin, Germany] or Ketac Cem [3M-Espe]). After storage in distilled water (24 h/37°C), the spreaders were pulled out in a universal testing machine at a crosshead speed of 2 mm/min. RESULTS: The failure mode was cohesive or adhesive at the cement-dentin interface in more than 80% of the experimental samples (control group: adhesive to the post: 9/10 samples). Adhesive luting materials retained posts better than conventional cements (t test, P < .001) but with a wide range in variation. RelyX Unicem displayed significantly higher values except when compared with Bifix SE and Clearfil SA (analysis of variance/Student-Newman-Keuls, P < .05). NX3, SmartCem2, and GCem showed no significant differences to Hoffmann's cement and Ketac Cem. CONCLUSIONS: The novel pull-out approach served well in testing the bond strength of different cements to root canal dentin. The bonding effectiveness of adhesive cements varied significantly and was material specific.

Secondary protective seal of root canal fillings performed under simulated clinical conditions

Objective: This study evaluated sealing properties of root canal fillings with an additional composite barrier. The null hypothesis tested was that different sealers and different methods of sealer removal did not influence microleakage. Material and methods: Eighty extracted human molars with fully mature apices had root canal prepared to size 60 taper .02 and divided into eight groups: three experimental groups for each sealer and negative/positive control (n = 10 each). Teeth of experimental groups were mounted into the molar region of a training puppet to simulate clinical conditions. Root canals were filled with AH Plus or GuttaFlow and gutta-percha. Excess sealer was removed with: ethanol-moistened foam pellet only, additional preparation with a water-cooled diamond bur or additional etch-and-rinse procedure (37% phosphoric acid gel). All procedures were carried out until clean as judged by the naked eye. In all groups except the positive control Syntac was applied to the access cavity. Tetric flow was applied in two increments of 1 mm each. A dye penetration test was carried out by centrifugation for 3 min at 30 G within 5% methylene blue dye. Statistical evaluation was carried out with PASW 18.0 (α = 0.05). Results: Although the two sealers had different chemical composition, sealer exhibited no influence on the results, whereas technique of sealer removal did (Two-way-ANOVA, p < 0.001). Groups with "foam pellet" or "bur preparation" showed significantly more leakage than groups with "etch-and rinse" (SNK, p < 0.05). Conclusion: Applying an etch-and-rinse procedure prior to Syntac may be beneficial for the adhesive seal over root canal fillings.

Strength and wear resistance of a dental glass-ionomer cement with a novel nanofilled resin coating.

PURPOSE: To evaluate the influence of different resin coating protocols on the fracture strength and wear resistance of a commercial glass-ionomer cement (GIC). METHODS: A new restorative concept [Equia (GC Europe)] has been introduced as a system application consisting of a condensable GIC (Fuji IX GP Extra) and a novel nanofilled resin coating material (G-Coat Plus). Four-point fracture strength (FS, 2 x 2 x 25 mm, 14-day storage, distilled water, 37 degrees C) were produced and measured from three experimental protocols: no coating GIC (Group 1), GIC coating before water contamination (Group 2), GIC coating after water contamination (Group 3). The strength data were analyzed using Weibull statistics. Three-body wear resistance (Group 1 vs. Group 2) was measured after each 10,000 wear cycles up to a total of 200,000 cycles using the ACTA method. GIC microstructure and interfaces between GIC and coating materials were investigated under SEM and CLSM. RESULTS: The highest FS of 26.1 MPa and the most homogenous behavior (m = 7.7) has been observed in Group 2. The coated and uncoated GIC showed similar wear resistance until 90,000 cycles. After 200,000 wear cycles, the coated version showed significantly higher wear rate (ANOVA, P< 0.05). The coating protocol has been shown to determine the GIC fracture strength. Coating after water contamination and air drying is leading to surface crack formation thus significantly reducing the FS. The resin coating showed a proper sealing of GIC surface porosities and cracks. In terms of wear, the coating did not improve the wear resistance of the underlying cement as similar or higher wear rates have been measured for Group 1 versus Group 2.

Adhesive coronal seal of Syntac and Tetric flow following different dentine pretreatment protocols

Introduction: The purpose of this study was to test different sealerremoval protocols following root canal filling before adhesive seal ofaccess cavities. Material and methods: Forty single root teeth wereselected for the study, prepared to size 60 taper .02, and filled withAH plus and a single gutta-percha cone size 55 taper .02. Excesssealer was removed with: ethanol-moisturised foam pellet (group 1),pellet and additional etch-and-rinse procedure (group 2), pellet andadditional preparation with a water-cooled diamond bur (group 3) orby etch-and-rinse following temporary filling for one week (group 4).Syntac and Tetric flow were used as a secondary protective seal. Adye penetration test (centrifugation 3min / 30G; 5% methylene blue)was carried out. Results were analyzed statistically using PASW 18.0(Kolmogorov-Smirnov-test, Kruskal-Wallis-test, Mann-Whitney-test;p < 0.05). Results: Groups 2, 3 and 4 revealed less leakage than group 1(p < 0.05; Mann-Whitney-tests) and displayed no coloration exceedingthe adhesive seal. Teeth with immediate (group 2) or delayed (group4) adhesive seal showed similar results. Conclusion: Acid etching orbur preparation may be recommended before adhesively sealing theaccess cavity in single-rooted teeth. There is no need to wait until thesealer has set.

Clinical adhesive sealing of the pulp chamber following endodontic treatment: influence of thermomechanical loading on microleakage.

PURPOSE: To test the influence of thermomechanical loading and mode of cleaning the pulp chamber on coronal microleakage of adhesive sealings over root canal fillings. MATERIALS AND METHODS: Root canals of molars were instrumented to size 60 taper .02 and filled with AH plus (Dentsply DeTrey) and a single gutta-percha cone size 55 taper .02. After removal of residual sealer with an alcoholmoistened foam pellet, different pretreatments were performed: groups 1 and 5: no further pretreatment; groups 2 and 6: use of a water cooled high-speed diamond bur; groups 3 and 7: etch-and-rinse with 37% H3PO4 for 10 s; groups 4 and 8: diamond bur and etching. Then Syntac (Ivoclar Vivadent) and two consecutive layers of Tetric flow (Ivoclar Vivadent) were applied. After placing glass-ionomer cement as a provisional restoration, teeth of groups 5 to 8 were additionally subjected to thermomechanical loading (chewing simulation of 200,000 cycles/50 N) and thermocycling (2880 cycles between 5 degrees C and 55 degrees C). A dye penetration test (methylene blue dye 5%, centrifugation for 3 min at 30 G) was used to evaluate linear dye penetration and dye penetration area. Statistical tests were performed using SPSS Win 12.0 (Kolmogorov-Smirnov test, two-way ANOVA, t-test). RESULTS: Thermomechanical loading (TML) had a negative impact on coronal seal (two-way ANOVA, p < 0.001). Among TML groups, group 7 (etch-and-rinse) performed best, exhibiting the least influence of TML. CONCLUSION: For adhesive sealing of the pulp chamber floor, the etch-and-rinse technique combined with a flowable resin composite showed promising results. Nevertheless, a stabilizing restoration should be placed as soon as possible.

Influence of moisture on the apical seal of root canal fillings with five different types of sealer.

The aim of this study was to evaluate the influence of moisture on apical leakage using five different types of sealer. There were 120 single-rooted teeth instrumented to .02/#60 and randomly assigned to 10 experimental groups, one control group (AH Plus, lateral condensation) (n = 10) or positive/negative controls (n = 5). Before obturation teeth were dried thoroughly, followed by recontamination with moisture in a wet chamber (moist groups; 37 degrees C for 7 days). The teeth of the experimental groups (a, dry; b, moist) were obturated with sealer (groups 1, AH Plus; 2, Apexit; 3, Ketac-Endo; 4, RoekoSeal; 5, Tubli-Seal) and a single gutta-percha cone .02/#55. Teeth were centrifuged (30 x g for 3 minutes) in 5% methylene blue. Linear dye penetration was measured under a stereomicroscope. Moisture led to less microleakage for Apexit, RoekoSeal, and Tubli-Seal and higher values for AH Plus and Ketac-Endo. Multifactorial ANOVA displayed a significant dependence of leakage on sealer (p < 0.001) and the combination sealer or moisture (p < 0.01). It depends on the sealer type in which way moisture affects the apical seal.

Ceramic inlays bonded with two adhesives after 4 years.

OBJECTIVE: The aim of the present study was to clinically evaluate the effect of two different adhesive/resin composite combinations for luting of IPS Empress inlays. METHODS: Ninety-four IPS Empress restorations were placed in 31 patients in a controlled prospective clinical split-mouth study. The restorations were luted with EBS Multi/Compolute (3M Espe) or with Syntac/Variolink II low (Ivoclar Vivadent) without lining. At baseline and after 0.5, 1, 2, and 4 years, the ceramic restorations were examined according to modified USPHS codes and criteria. RESULTS: Two patients including four restorations missed the 4 years recall (drop out). After 4 years of clinical service, four restorations in two patients (three luted with Compolute, one with Variolink II) had to be replaced due to hypersensitivities, 90 inlays and onlays were acceptable (failure rate 4%; Kaplan-Meier survival analysis). Between the five recalls, a statistically significant deterioration was found for the criteria marginal adaptation and inlay fracture (Friedman 2-way ANOVA; p < 0.05). Between the adhesives no statistical difference was found. At baseline, 95% of the restorations revealed luting composite overhangs. After 4 years, 55% of cases had overhangs and 38% showed marginal ditching. No differences were found for surface roughness, color matching, integrity tooth, proximal contact, hypersensitivity, and satisfaction (p > 0.05). CONCLUSION: For luting of ceramic inlays, no difference between the two luting systems was detectable. The overall failure rate after 4 years was 4%.

Fatigue behavior of the resin-resin bond of partially replaced resin-based composite restorations.

PURPOSES: (1) To evaluate different pre-treatment modes for partial resin-based composite repair using a shear bond strength fatigue design on aged specimens, and (2) to investigate the effect of these pre-treatments on aged and partially replaced Class II resin-based composite restorations. MATERIALS AND METHODS: (Study 1) 150 composite discs (Tetric Ceram) were light-cured, secondary cured, and stored in water for 365 days. The specimens were randomly assigned to five pretreatment groups (n=30): (1) Roughening with a finishing diamond bur + dentin bonding system (DBS, Syntac Classic), (2) Roughening with a silicon carbide bur + DBS, (3) Roughening with a silicon carbide bur + DBS + Tetric Flow, (4) silica-coating (CoJet) + DBS, and (5) silica-coating + dentin bonding agent + Tetric Flow. The disks were restored with fresh repair composite cylinders and after 24-hour water storage, initial bond strengths (n=10) and fatigue bond strengths (n=20; 5,000 cycles in shear mode) were evaluated and fracture modes determined under a SEM. (Study 2): 40 Class II restorations (EBS Multi/Pertac II) were placed in extracted human third molars. The specimens were stored for 365 days and then replaced partially by removing the proximal box and leaving the occlusal part. The partial repairs (Pertac II) were placed after identical pre-treatment modes A-E (n=8). After thermomechanical loading (100,000 x 50 N, simultaneously x2,500 at 5 degrees C/55 degrees C), marginal quality between old and fresh composite was evaluated by SEM at x200 magnification and dye penetration was observed by light microscopy under x50 magnification. RESULTS: Initial repair bond strengths were significantly higher for the groups with additional application of flowable composite compared to composite only (P<0.05; Mann Whitney U test). Diamond finishing revealed the lowest bond strengths. Fatigue bond strengths exhibited the worst results for Group 1 as well, but were similar for Groups 2-5. In the Class II partial repair simulation, Groups 3 and 5 with additional flowable lining exhibited significantly better marginal quality and significantly lower leakage, whereas the other groups revealed up to 100% separation between aged and freshly applied composite.