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Statement of problem. Although endodontically treated tooth is less likely to break when there is enough remaining tooth structure, controversy exists concerning the remaining coronal tooth structure of endodontically treated maxillary incisors.Purpose. The aim of this investigation was to access the resistance to fracture of endodontically treated maxillary incisors with four walls and those with three walls of remaining coronal tooth structure and the influence of the site of the missing coronal wall. Material and methods. Forty endontically treated maxillary central incisors were decoronated according to the criteria of each group, leaving 3 mm above the cemento-enamel junction (CEJ). A 0.5-mm-wide chamfer was prepared 1 mm above the CEJ. The teeth were randomly divided into four groups (n=10) Group 1 had four walls of coronal tooth structure (control group), whereas groups 2, 3, and 4 had only three walls, missing the labial, palatal, and mesial wall respectively (test groups). The cast dowel and cores and crowns Ni–Cr-Be base metal alloy were fabricated and cemented with Panavia 21 cement. A compressive load was applied 45-degree to the long axis with an Instron machine until failure at a crosshead speed of 0.5 mm/min. Failure load was recorded in N and data were analyzed with 1-way ANOVA, followed by multiple comparisons using Tukey HSD test (α=.05).Results. The mean failure load (N) of teeth with four walls (965.7 ± 37.7 N) was significantly higher from teeth with three walls (P

SUMMARY The absolute marginal gap (AMG) precementation and postcementation and the retention of zirconia crowns cemented to standardized molar preparations (4×10) by self-adhesive resin cements (SARCs) were evaluated. The following SARCs were used: RelyX U-200 (RXU200; 3M ESPE, Seefeld, Germany), SmartCem 2 (SC2; Dentsply, Milford, DE, USA), and G-Cem Automix (GCA; GC, Alsip, IL, USA). The control adhesive resin cement was Panavia 21 (PAN; Kuraray Dental Co Ltd, Osaka, Japan). Twenty measuring locations at a constant interval along the margins were marked, and the AMG was measured by an image analysis system connected to a stereomicroscope (20×). The cemented copings were aged 270 days at 100% humidity and 37°C and then underwent 10,000 thermal cycles, 5°C-55°C. After aging, the crowns were tested for retention, and the debonded surfaces were examined at 3× magnification. The mean marginal gaps precementation and postcementation were 34.8 ± 17.4 μm and 72.1 ± 31 μm, respectively, with no statistically significant differences between the cements. A significant difference (p≤0.001) in retention between the cements was found. The highest values were obtained for SC2 and GCA (1385 Pa and 1229 Pa, respectively), but these presented no statistically significant differences. The lowest values were found for PAN and RXU200 (738 Pa and 489 Pa, respectively), but these showed no statistically significant differences. The predominant mode of failure in all of the groups was mixed, and no correlations were found between marginal gap and retention.

PURPOSE: This in vitro study measured push-out bond strength of different posts as function of radicular regions. Statement of problem: In non circular or excessively flared root canals,prefabricated posts may not fit well,increasing cement thickness and bubbles at coronal level which may alter its mechanical performance causing impaired post retention.Methods:40 sound extracted human central incisors were used in this study. All teeth were endodontically treated and decoronated 2 mm above CEJ. Then were randomly divided into 4 groups of 10 each regarding type of post used:group 1(PD): Polymer infiltrated ceramic,Paradigm MZ 100(3M-ESPE); group 2(FRC)Fiber post,Postec Plus (Ivoclar Vivadent); group 3 (ZR): Lava Zirconium dioxide blocks (3M-ESPE); group 4(CP):Cosmo Post, Zirconium dioxide (Ivoclar Vivadent). All posts were luted with Panavia 21(Kuraray Noritake, Japan). Push-out tests were performed to evaluate the bond strength of different posts at different radicular regions.Data were statistically analyzed using one way (ANOVA)and Scheffe test made pairwise comparison (α=0.05).Results: FRC group recorded the highest bond strength (11.78±0.79MPa). PD group showed higher results (10.10±1.12MPa) than ZR(9.56±0.85MPa) and CP(7.93±0.89 MPa) and the 2 latter groups were not significantly different from each other p≤0.05.Regardless to post type, it was found that middle region recorded highest bond strength means value, then apical region meanwhile the lowest bond strength values were recorded at cervical regions p≤0.05.Conclusions:1- Push-out bond strength of different esthetic posts are significantly affected by the type of its materials and manufacturing; FRC recorded the highest bond strength values,PD recorded intermediate values, ZR and CP showed the least values with no significant difference between them.(P≤0.05) 2-Regardless to type of post , the middle radicular region recorded the highest bond strength then apical region, meanwhile cervical region showed the lowest bond strength values P≤0.05.

Background To evaluate a potential correlation between flexural strength and indirect tensile strength in assessing the mechanical strength of resin composite cements. Methods Flexural strength (n = 5) and indirect tensile strength (n = 5) of 7 resin composite cements (RelyX Unicem 2 Automix [RXU], Panavia SA [PSA], Clearfil SA [CSA], Panavia F2.0 [PF2], Multilink Implant [MLI], DuoCem [DCM], Panavia 21 [P21]) were determined. Specimens were either auto-polymerized or dual-cured (except P21) and stored in water at 37 °C for 1 day prior to measurement. Flexural and indirect tensile strength of 4 cements (RXU, PSA, PF2, MLI) was additionally measured directly after curing and after 96 h water storage at 37 °C. Results Except for PF2, dual-cured specimens achieved higher flexural strength than auto-polymerized specimens. In the indirect tensile strength test differences in auto-polymerized and dual-cured specimens were only detected for RXU and DCM. A general non-linear correlation was found between flexural and indirect tensile strength values. However, strength values of auto-polymerized and dual-cured specimens did not generally correlate. Conclusions Flexural strength and indirect tensile strength of resin composite cements are correlated. At high strength values the indirect tensile test is less sensitive than the flexural test. The results suggest that the indirect tensile test may only be recommended as a screening test especially for low or medium strength resin composite cements.

Objectives This study evaluated the clinical outcome of all-ceramic resin-bonded fixed partial dentures (RBFPDs) with a cantilevered single-retainer design. Methods Thirty anterior zirconia ceramic RBFPDs were inserted using either a phosphate monomer containing resin (Panavia 21 TC; N = 16) or an adhesive bonding system with a phosphoric acid acrylate primer (Multilink–Automix with Metal/Zirconia primer; N = 14). Results During a mean observation time of 41.7 months one debonding occurred in each group. Both RBFPDs could be rebonded successfully resulting in a three-year survival rate of 100%. Conclusion Independent of the bonding system cantilevered zirconia ceramic RBFPDs showed promising results during the first three years. Clinical significance Single-retainer zirconia ceramic RBFPD present an alternative treatment option offering good aesthetics, a minimal invasive preparation, a high biocompatibility and can even be used to treat juvenile patients who do not yet come into consideration for implant placement. No significant influence of the bonding system used was detected so far.

Die Befestigung von Zirkoniumdioxidkeramik am Zahn ist sowohl mit konventionellen als auch mit adhasiven Zementen moglich. Untersuchungen belegen, dass die adhasive Zementierung wesentliche Vorteile in Bezug auf Bruchfestigkeit und Randdichte gewahrt (Geiselhoriger und Holst 2007). Die vorliegende in vitro Studie untersucht die Haftung von adhasiv zementierter Zirkoniumoxidkeramik auf Dentin mit drei verschiedenen Kompositzementen. Die Proben wurden laut Herstellerangaben fur den jeweiligen Zement verklebt und in 2 Versuchsreihen einem ThermocyclingProzess zu 5.000 bzw 10.000 Zyklen unterzogen. Nach diesem simulierten Alterungsprozess wurden die Proben abgeschert, die erforderliche Scherkraft gemessen und die Entwicklung der Haftwerte im Vergleich zwischen den unterschiedlichen Thermocycling-Durchlaufen untersucht. Es konnten signifikante Unterschiede zwischen den jeweiligen Zementen in den verschiedenen Versuchsreihen festgestellt werden.

Objectives Assessment of dental material biocompatibility is gaining increasing importance for both patients and dentists. Dental cements may be in contact with oral soft tissues for prolonged periods of time and play an important role in prosthetic rehabilitation. The aim of the present study was to evaluate eight dental cements using a standardized L929-fibroblast cell culture test. Methods For each material, fresh specimens (added to the cultures immediately after preparation) and specimens preincubated for 7 days in cell culture medium were prepared according to the manufacturers’ recommendations. After exposure to test specimens, cell numbers were compared to glass controls. The main outcome was a two-sided 95% confidence interval for the mean value of the standardized cell number for each substance investigated. Results Fresh specimens of all tested cements showed significant cytotoxicity, which diminished after 7 days preincubation. Cytotoxicity of fresh adhesive and self-adhesive resin cements was lower when specimens were dual-cured compared to self-cured. A rank order of cytotoxicity was established based on mean values: Nexus 2 (dual-cured) showed least cytotoxicity, followed by Variolink II (dual-cured), Nexus 2 (self-cured), Harvard, RelyxUnicem (dual-cured), Panavia 21, Fujicem, Durelon, Variolink II (self-cured), RelyxUnicem (self-cured), Maxcem (dual-cured) and Maxcem (self-cured). When bondings were added to Nexus 2 or Variolink II specimens, a slight increase in cytotoxicity was observed. Significance Adhesive resin cements showed less cytotoxicity than self-adhesive and chemically setting cements. Bonding only slightly influenced cytotoxicity of the adhesive resin cements. Dual-cured specimens of adhesive and self-adhesive resin cements showed significantly less toxicity than self-cured specimens.

Objectives To evaluate the push-out bond strength and the sealing ability of five adhesive cements routinely used for fiber-post bonding. Methods Fifty extracted single-rooted teeth were randomly divided in five groups and restored using Parapost FiberLux and the following luting agents: Panavia 21 (PAN), Clearfil Esthetic Cement (CLF), Variolink II (VAR), RelyX Unicem (UNI) and experimental GC self-adhesive cement (EGC). After 1 week of water storage at 37 °C, three sections (coronal, middle and apical) of 2 mm thickness were prepared from each specimen. Sealing ability was quantified with a fluid-filtration system (Flodec) during 10 min, after which the push-out bond strength was immediately measured. Data were analyzed with ANOVA (push-out) and Kruskal–Wallis (sealing ability). Results The push-out bond strength and sealing ability were not significantly different among the coronal, middle and apical sections for each luting agent. The highest push-out bond strength was measured for CLF (14.60 ± 3.63 MPa), which was not significantly different from PAN (12.57 ± 2.45 MPa), but significantly higher than VAR (11.09 ± 4.09 MPa), UNI (11.29 ± 4.31 MPa) and EGC (7.65 ± 4.79 MPa). When evaluating the sealing ability, significant differences were not found among PAN, CLF and VAR, and between UNI and EGC. The latter luting agents scored significantly lower than the former ones. The push-out bond strength was correlated to the sealing ability (p Significance The self-etching MDP-based cements presented the highest push-out bond strength. Although the bonding effectiveness of self-adhesive cements appears promising, their interaction with root dentin might be too weak to minimize microleakage at the post–cement–dentin interface.

This study compared the ability of various intracanal restorative materials to restore the stiffness of endodontically treated teeth. We randomly placed bovine central incisors into six groups. We did not instrument negative control teeth, and we instrumented, but did not restore, positive control teeth. We restored teeth in the experimental groups with resin-based composite, resin-based composite plus a fiberglass post, or resin-based composite plus a cemented metal post. We subjected all teeth to nondestructive, compressive testing and recorded the stiffness of each sample. Results indicated that performing endodontic access and instrumentation alone resulted in a 24% loss in tooth stiffness. Teeth restored using an intracanal resin bonding technique alone or in combination with a post regained the stiffness lost from access and instrumentation, and teeth that were restored with bonded resin and a metal post cemented with Panavia 21 cement were significantly stiffer than the untreated negative control group (p0.05). Our results suggest that intracanal resin bonding techniques may reduce the need for immediate crown placement after endodontic therapy.

Hagge MS, Wong RDM, Lindemuth JS. Effect of three root canal sealers on the retentive strength of endodontic posts luted with a resin cement. International Endodontic Journal, 35, 372–378, 2002. Aim This investigation examined what effect three different sealers had on retention of endodontic posts (Parapost) luted with a resin cement (Panavia 21 OP). Methodology Sixty-four single-rooted teeth were decoronated, filed, cleaned, and shaped with a size 5 Gates–Glidden drill and 0.12 taper G.T. rotary instrumentation (Dentsply/Tulsa Dental). Teeth were then divided into four groups of 16 each. Group 1 was not obturated, and served as a control. The other three groups were obturated with gutta-percha using a different sealer for each group. Group 2 used a eugenol containing sealer (Kerr Pulp Canal Sealer), group 3 a resin sealer (AH-26), and group 4 a calcium hydroxide sealer (Sealapex). After 1 week’s storage at 100% humidity, 10-mm deep post spaces were prepared with a size 6 Gates–Glidden drill, and size 5 Paraposts were cemented. Following 48 h of storage, samples were mounted in a PVC pipe with acrylic, and the posts were removed vertically using a universal testing machine at 1 mm min−, with data recorded in kilograms. Results The mean values of force required to remove the posts were: group 1 = 61.80, SD = 16.21; group 2 = 43.14, SD = 14.66; group 3 = 48.54, SD = 17.84; group 4 = 53.52, SD = 18.77. Using anova and Bonferroni tests, group 1 demonstrated significantly greater mean retention strength values than group 2, but no other significant differences existed between groups. Conclusion The chemical formulation of root canal sealers did not significantly affect the retention of endodontic posts luted with resin cement.

Purpose: To evaluate the survival of maxillary anterior cantilever resin-bonded metalceramic (MC) and all-ceramic (AC) fixed dental prostheses (RBFDPs). Materials and Methods: Between August 2007 and December 2009, 40 patients received 40 RBFDPs made of either cobalt-chromium-ceramic (n = 20) or glass-infiltrated alumina (In-Ceram, Vident; n = 20) and were followed up until December 2012. Restorations were adhesively cemented (Panavia 21, Kuraray). Results: Two fractures were observed with AC. No debondings were observed with MC (n = 0) but were observed with AC (n = 3). The difference in survival rates of MC and AC was not significant (MC: 100%; AC: 90%; P = .15) (Kaplan-Meier method, confidence interval = 95%). Conclusions: Cantilever AC RBFDPs could be a promising alternative to MC RBFDPs for replacement of missing anterior incisors, provided that no mechanical complications were experienced with the latter

The purpose of this study was to test in shear mode the bond strengths of two BIS-GMA resin cements bonded to alumina blasted and heat-treated gold alloy surfaces. This was carried out in order to investigate the manufacturer's claim of the superiority of Panavia 21 over Panavia Ex. Alumina blasted gold alloy surfaces were cemented in pairs with either Panavia Ex or Panavia 21 resin cements. Heat-treated gold alloy surfaces were similarly paired. The luted pairs were stored in water at 37 degrees C for 48 h before bond was tested with shearing forces. Although the differences were not statistically significant, it was found that Panavia 21 formed stronger bonds on the alumina blasted surfaces than Panavia Ex. However, Panavia Ex exhibited higher mean strength values than Panavia 21 on the heat-treated surfaces. Not only was this difference statistically significant, but the bond strength values obtained for Panavia Ex on this surface were the highest in the data set. On the basis of bond testing in shear, it would appear that Panavia 21 is inferior to Panavia Ex on heat-treated gold alloy surfaces.

The introduction of resin-modified glass ionomer cements has expanded the choices of luting cements available to the clinician; however, few independent studies are available on the fracture toughness of the currently available resin-modified glass ionomer luting agents compared with the composite cements.This investigation evaluated the relative fracture toughness (K(IC)) of 3 composite luting cements (Panavia 21, Enforce, and CB Metabond), 3 resin-modified glass ionomer luting cements (Advance, Vitremer Luting, and Fuji Duet), and a conventional glass ionomer luting cement (Ketac-Cem) at 24-hour and 7-day storage times.K(IC) was determined by preparing minicompact test specimens (n = 8) with introduced precracks. Specimens were stored in distilled water at 37 degrees C + 2 degrees C until testing. Testing was performed on an Instron testing machine at a displacement rate of 0.5 mm/min.ANOVA (P.001) and REGW Multiple Range Test (P.05) demonstrated significant differences among several of the cements tested. The mean fracture toughness values of CB Metabond at 24 hours and Enforce at both 24 hours and 7 days were significantly greater than use any of the other cements tested.The resin-modified glass ionomer cements exhibited improved fracture toughness when compared with the conventional glass ionomer; however, they were still inferior to Enforce and CB Metabond composite cements.

Aim The purpose of this study was to evaluate the sealing ability of two contemporary endodontic obturation and restorative techniques and materials. Methodology Seventy-nine extracted human single-rooted teeth were distributed randomly in two experimental groups of 36 and 37 specimens (groups 1 and 2, respectively), one group of three positive controls and one of three negative controls. The teeth were radiographed preoperatively, accessed, and instrumented. After smear layer removal, the teeth in group 1 were obturated using the System B and Obtura and were restored coronally with Core Paste using Tenure as a bonding agent. The teeth in group 2 were obturated using the Microseal technique and were restored coronally with amalgam using Panavia 21 as a bonding agent. All teeth in groups 1 and 2 were coated with three layers of nail varnish on all of their surfaces apart from the apical 4.0 mm and the coronalarea above the cemento-enamel junction. The positive control teeth were obturated, restored coronally and completely coated with varnish, whereas the negative control teeth were not obturated, restored coronally, nor coated with varnish. The teeth were radiographed postoperatively and retained in saline solution for 10 days. For the next 10 days they were submerged in India ink. Subsequently all teeth were demineralized, dehydrated and rendered transparent. Dye penetration was measured using a stereomicroscope. Results All materials and techniques provided minimal to zero dye penetration, apart from one specimen in the Core Paste group that showed 4.0 mm of dye penetration. The Wilcoxon rank sum test and t-test showed no statistically significant differences and all materials and techniques tested presented with a high degree of acceptability. Conclusions It was concluded that these contemporary techniques and materials provide equally good results, but long-term studies are needed for outright inferences to be drawn relative to their clinical performance.

The purpose of this study was to evaluate the clinical strength of castable glass-ceramic (OCC, Olympus Optical Co., Japan) restorations.On 38 patients, from February 8, 1994 to December 19, 1996 at Aichi-Gakuin University Dental Hospital, 154 castable glass-ceramic restorations were cemented.These restorations were reexamined February 1998 and an analysis of fractures in the restorations was performed. Observed fractures as well as cracking or chipping and 22.7% of the restorations were considered fractured, and the longest survival time until now has been 48 months. The Kaplan-Meier survival probability calculated for these restorations was 0.86 using Panavia 21 and 0.90 using Panavia EX after a time interval of 24 months, and 0.66 using Panavia 21 and 0.82 using Panavia EX after a time interval of 36 months. There were no significant differences in the survival between the two cements.It was then con cluded that castable glass-ceramic restorations are suitable for clinical use, although some problems remain, especially with the successful lifetime of the castable glass-ceramics.

— This in vitro study investigated the fracture strengths of fractured incisors after reattachment to the remaining tooth structure, using either Gluma dentin-bonding agent together with 1 of 13 different experimental resins or 1 of the following dentin-bonding agents: Gluma+ (experimental modification of Gluma), Panavia 21, ScotchBondl (SingleBond), All-Bondz, Dentastic, Super-Bond, Prime & Bond 2.1. No siwcant differences were found in the experiments with various experimental resins. The fracture strength of teeth rebonded with Gluma, All-Bondz, Dentastic, SuperBond or Prime & Bond 2.1 showed mean fracture strengths in the range of 8.7–11.2 MPa, which were significantly different in all cases from that of intact teeth (16.3 MPa). Teeth bonded with Gluma+, Panavia 21 or ScotchBondl (SingleBond) showed mean fracture strengths of 15.5, 14.6, and 14.2 MPa, respectively. These fracture strengths were not significantly different from that of intact teeth.

Although selection of clinically reliable bonding system is essential, limited information concerning the combination of durable ceramic bonding and luting agents is available.This in vitro study was conducted for the purpose of evaluating bond strengths of ceramic bonding materials in conjunction with their initiation and silane-activation modes.Disk-shaped fired porcelain specimens were air-abraded with alumina, then bonded with six combinations of three silane priming and two luting agents; specimens were also bonded with two luting cements without priming. Shear bond strengths were determined both before and after thermocycling.For the two unprimed control groups, as well as two of the groups bonded with Panavia 21 cement (Clearfil Porcelain Bond and Panavia 21; Panavia Ceramic Primer and Panavia 21) the reduction in bond strengths after thermocycling was remarkable as compared with the corresponding prethermocycling groups (p0.05). A dual-cured luting cement (Clapearl DC) used with each of three silane priming materials (Clapearl Bonding Agent, Clearfil Porcelain Bond, and Panavia Ceramic Primer) exhibited consistent shear bond strength greater than 30 MPa after 20,000 thermocycles.The above three systems appeared to be useful for the long-term clinical success of feldspathic porcelain restorations.

Statement of problem. Adhesive resin luting agents are used to successfully bond the metal surfaces of fixed prostheses to teeth. Panavia 21 luting agent is a new addition to the series of Panavia adhesive resin luting agents. Purpose. This investigation measured the shear bond strengths of two types of alloy specimens (Olympia and Rexillium III) bonded to prepared human enamel (etched and unetched) with Panavia 21. Material and methods. After a simulated porcelain firing sequence, the alloy specimens were bonded to the teeth and subjected to shear testing after water storage for 2 weeks, thermocycling for 500 cycles, and water storage for an additional 2 weeks. Data were analyzed with a two-way analysis of variance (alpha = 0.05). Results. The shear bond strengths of Rexillium III and tinplated Olympia specimens bonded to prepared and unetched enamel were significantly lower than for specimens bonded to prepared and etched enamel with Panavia 21 luting agent. (J Prosthet Dent 1997;78:132-5.)

SiO2 type glass ceramics (OCC), which educe mica and -spodiumen crystals, were developed in the 1980 s and clinically applied in 1986. On a commercial basis, some of the clinical failure cases developed, and since 1995, properties of the material and technique have been reexamined. OCC restorations are now cemented by Panavia 21, a luting agent.Some of the main improvements of OCC to prevent failure are as follows: Currently used pellet type was changed to powder type and stabilization of the material was attempted. In the laboratory technique, polishing of OCC restorations, which has been done after ceraming, was done before ceraming, in the state of as-cast because processed micro cracks became obtuse angles or diminished. The crystalization schedule was examined, and a modified schedule was found to be useful for obtaining small, constant sized crystal grains.Furthermore, applications of OCC to the artificial denture teeth or implant prosthesis and so on were discussed.

The differences due to the types of temporary cement and the period of temporary cementation as well as the effect of the pre-treatment during the adhesion on adhesive strength of the adhesive resin cement and dentin were evaluated by performing shearing adhesive strength test, by determining contact angle, and by scanning electron microscopy.The results were as follows:1. In Bistite Resin Cement and Imperva Dual, adhesive strength significantly increased more by etching treatment than by primer treatment. When Super Bond C & B was used, adhesive strength was 20 MPa or more regardless of the type of temporary cement and the period of temporary cementation. When Panavia 21 was used, adhesive strength increased significantly as the period of temporary cementation became longer except HY-BOND temporary cement.2. On the surface of dentin after removal of temporary cement, except HY-BOND temporary cement, and cleaning, the contact angle of the surface of dentin significantly decreased. After etching treatment, the contact angle of the dentin surface increased in most of the cases as the period of temporary cementation became longer.3. After the removal of temporary cement and cleaning, temporary cement remained on the surface of dentin, and the primer treatment of the dentin surface after removal of temporary cement and cleaning was not effective. However, by performing etching treatment on the dentin surface after the removal of temporary cement, except HY-BOND temporary cement and cleaning, smear plug was removed.

The purpose of this study was to evaluate and compare the mechanical properties, water sorption and solubility and shear bond strengths of eight commercially available luting agents to silver-palladiumcopper-gold (Ag-Pd-Cu-Au) dental alloy. Five adhesive resin cements, Bistite Resin Cement, Imperva Dual, Panavia EX, Panavia 21 and Super-Bond C & B and three conventional luting agents, zinc phosphate (Elite Cement 100), carboxylate (HY-bond Carbo Cement) and glass ionomer (Fuji Bond) were used. In general, resin cements except for Super-Bond C & B showed higher values of Knoop hardness and compressive, diametral and transverse strengths than conventional luting agents. Adhesive resin cements showed much less water sorption and solubility than ordinary cements. Adhesive luting agents maintained excellent bond strengths of approximately 27-37 MPa to Ag-Pd-Cu-Au alloy after 50, 000 thermocycles while alternately immersing the specimen in 4°C and 60°C water for one minute each. These results suggest that resip cements may be more clinically useful for cementing restorations than conventional luting agents.

Objectives Bonding of all-ceramic restorations has become routine practice mainly due to results from clinical studies. Sandblasting has been advocated for surface treatment of many ceramics, based on results from numerous in vitro studies. This present work examines the influence of bonding on fracture loads of a veneered alumina ceramic using both chemical and sandblasting treatments. Methods Veneered tabs (In-Ceram alumina) were cemented (50 μm; ZnPO 4 or Panavia 21) to dentin-analog bases designed to allow water penetration to the cement/dentin interface. 60 specimens were fabricated for 2 weeks storage and another 80 specimens for 6 months storage (water, 37 °C). Half of each group was tested “as-finished” and the other half “as-sandblasted”, each divided between two cements. Specimens were loaded cyclically (20 Hz, 500,000) cycles in water beneath a 3 mm diameter piston. A staircase sensitivity protocol was followed, using a step size of 25 N. Specimens were examined for cracking by transillumination (10×). Results Mean failure loads differed significantly between (1) as-finished Panavia versus zinc phosphate at 2 weeks; (2) as-finished versus sandblasted at 2 weeks; and (3) as-finished at 6 months versus 2 weeks (ANOVA, 95% post hoc test). Sandblasted groups did not differ among themselves at either time period or between 2 weeks and 6 months. Conclusion Sandblasting was important for maintaining failure loads after 6 months of water storage. Zinc phosphate was equally protective as Panavia for sandblasted groups. Adhesion testing may not replicate clinical stresses important for investigating protective cement effects.

The aim of this study was to evaluate the effect of primers, luting systems and aging on bond strength to zirconium oxide substrates. Eighteen zirconia discs (19.5 x 4 mm) were polished and treated (n = 3) either with a MDP primer (Md) or with a MDP and VBATDT primer (MV). In the control group (n = 3) no surface chemical treatment was performed. Zirconia specimens were cemented to prepolymerized composite discs utilizing resin cements - RelyX Unicem or Panavia 21 (RU and Pa, respectively). After 24 h, samples were sectioned for microtensile testing and returned to water at 37 degrees C for two different periods before being tested: 72 h or 60 days + thermocycling (5-55 degrees C/5000 cycles). Bond strength testing was performed at 1 mm/min. Values in MPa were analyzed through ANOVA and Tukey's Studentized Range (HSD) (p > 0.05). The application of MV primer resulted in the highest bond strength (22.77 MPa), statistically superior to Md primer (12.78 MPa), and control groups presented the lowest values (9.17 MPa). When luting systems were compared, RU promoted the highest bond strength (16.07 MPa) in comparison with Pa (13.75 MPa). The average bond strength decrease after aging (9.35 MPa) when compared with initial values (20.46 MPa). The results presented by this in vitro study suggest that a chemical surface treatment based on the MDP and VBATDT combination may improve bond strength between zirconia and luting system, without any previous mechanical treatment, depending on the luting system used. This chemical treatment may result in a reliable alternative to achieve adequate and durable bond strength.

Statement of problem A luting cement must maintain a minimum film thickness over a sufficient period of time to allow seating of indirect restorations. The performance of newer luting cements in this regard has not been evaluated. Purpose The purpose of this study was to compare the film thicknesses of 6 luting cements, 2 resin-modified glass ionomer (FujiCEM and RelyX Luting Plus), 2 composite resin (Panavia 21 and RelyX ARC), and 2 self-adhesive resin (Maxcem and RelyX Unicem) cements, over 3 minutes. Material and Methods The film thickness (μm) of each cement (n=7) was determined at room temperature at 1, 2, and 3 minutes after the start of mixing, according to the testing method set forth in ISO Standard 9917. Means of all cements were compared at the 2-minute interval, and means at the 1- and 3-minute intervals for each were compared to the mean for the same cement at 2 minutes, using 1-way analyses of variance (ANOVA) and Tukey-Kramer multiple comparison tests (α=.05). Results Except for 1 resin-modified material at 3 minutes, a point beyond its specified working time, all materials produced film thicknesses under 30 μm at 3 minutes and under 26 μm at 2 minutes. Conclusions All of the materials tested meet the ISO standard of 25-μm maximum film thickness for up to 2 minutes after mixing. (J Prosthet Dent 2009;101:189–192)

The resin-bonded bridge (RBB) is a predictable technique that has a useful place in modern day dentistry. Practitioners' main concerns, regarding this technique, are a lower survival rate when compared with conventional prostheses, and unpredictable aesthetics. Unfortunately, the minimal preparation and adhesive concepts used with RBBs complicates provisional cementation. Ideally, the RBB should be assessed as if it were the definitively bonded prosthesis. It is possible to achieve a good final aesthetic result as the grey shine-through of the metal wing can be eliminated by the use of opaque resin cements such as Panavia 21 OP. Ideally, the restoration should be assessed with an identical opaque try-in paste but, unfortunately, such a proprietary paste is not available. This paper describes the use of Dycal as a try-in paste for provisionally cementing a resin-bonded bridge and the benefits this offers.

The radicular portion of zirconia endodontic posts often need to be reshaped to achieve a definitive form and may be airborne-particle abraded to improve adhesion during luting. Therefore, the surface of the tetragonal zirconia ceramics may be transformed and damaged, influencing the mechanical properties of the material.This study compared the fracture resistance of prefabricated zirconia posts with a new retentive post-head after different surface treatments.Experimental zirconia posts of 2 different diameters, 1.3 mm and 1.5 mm, were produced from commercially available zirconia powder. A cylindro-conical outline form was used for the root portion of the system and a post-head with 3 retentive rings was designed. Sixty posts of each diameter were divided into 3 groups (n=20). Group 1 was ground with a coarse grit diamond bur; Group 2 was airborne-particle abraded with 110-microm fused alumina particles, and Group 3 was left as-received (controls). Posts were luted into the root-shaped artificial canals with the Clearfil adhesive system and Panavia 21 adhesive resin luting agent. The posts were loaded in a universal testing machine at an inclination of 45 degrees with the constant cross-head speed of 1 mm/min. The fracture load (N) necessary to cause post fracture was recorded, and the statistical significance of differences among groups was analyzed with 1-way ANOVA followed by the Fischer LSD test (alpha=.05). The variability was analyzed using Weibull statistics.Load to fracture values of all zirconia posts depended primarily on post diameter. Mean fracture loads (SD) in Newtons were 518.4 (+/-101.3), 993.6 (+/-224.1), and 622.7 (+/-110.3) for Groups 1 through 3, respectively, for thicker posts, and 385.9 (+/-110.3), 627.0 (+/-115.1), and 451.2 (+/-81.4) for Groups 1 through 3, respectively, for thinner posts. Airborne-particle-abraded posts exhibited significantly higher resistance to fracture (P.05) than those in the other 2 groups for diameters 1.3 mm and 1.5 mm. Grinding reduced Weibull modulus compared with controls, and the values were 4.1 and 6.5 for thicker and thinner posts, respectively.Within the limitations of this study, the results suggest that grinding leads to a significant drop in load to fracture of zirconia posts, whereas airborne-particle abrasion increased the fracture load.

CAD-CAM restorative materials are popular because they have high esthetic value and short fabrication time. Unfortunately these materials are brittle and tend to fracture under heavy occlusal load.The purpose of this in vitro study was to investigate the tensile bond strengths of 5 luting agents to 2 CAD-CAM restorative materials and enamel. Material and methods One hundred truncated cones, with a 3-mm diameter bonding surface and 5-mm diameter base, were fabricated with Dicor MGC (n=50) or Cerec Vitablocs Mark II (n=50) with the Cerec system. Enamel surfaces of the crowns of 100 freshly extracted noncarious, anterior teeth, stored in 0.9% saline solution with 0.25% sodium azide (NaN(3)) as disinfectant, were prepared with sandpaper disks (320-grit size) on the Buehler Variable Speed Grinder-Polisher. The bonding surfaces of the Dicor MGC or Cerec Vitablocs Mark II truncated cones from each of the 2 tests systems were airborne particle abraded, chemically etched, and cemented on the prepared enamel surface of the tooth specimens with 5 luting agents: Vita Cerec Duo Cement, EnForce, Panavia 21, CB Metabond, and Fuji Duet. All specimens were thermocycled 1000 times, in 5 degrees C and 55 degrees C water with a dwell time of 30 seconds in each temperature. Tensile force (MPa) was applied perpendicular to the bonding surfaces of the specimens with a universal testing machine until fracture. Fracture patterns were examined with a microscope at original magnification x10. The differences in the tensile bond strengths were analyzed with the Tukey-Kramer test (alpha=.05).The mean tensile bond strengths of Dicor MGC bonding to enamel with luting agents in descending order in MPa were EnForce (10.12 +/- 2.25), Panavia 21 (7.28 +/- 1.77), Cerec Duo (5.32 +/- 1.65), Fuji Duet (3.73 +/- 1.78), and CB Metabond (3.11 +/- 1.11). EnForce had a significantly higher bond strength than CB Metabond, Fuji Duet, Cerec Duo, and Panavia 21 (P=.05). The mean tensile bond strengths of Cerec Vitablocs Mark II bonding to enamel with luting agents in descending order in MPa were as follow: Fuji Duet (11.51 +/- 2.79), EnForce (9.44 +/- 2.03), CB Metabond (8.98 +/- 3.29), Cerec Duo (8.66 +/- 4.71), and Panavia 21 (5.10 +/- 2.49). Within this group, there was no significant difference between Fuji Duet and EnForce, but the bond strength of Fuji Duet was significantly higher than that of CB Metabond, Panavia 21, and Cerec Duo (P=.05). The mean tensile strength of all the luting agents bonded to Cerec Vitablocs Mark II and enamel (8.74 MPa) was higher than Dicor MGC and enamel (5.91 MPa).In this in vitro study; within the Dicor MGC group, the mean bond strength of Panavia 21 with enamel was significantly higher than CB Metabond, Panavia 21, Cerec Duo, and Fuji Duet. Within the Cerec Vitablocs Mark II group, the mean bond strength of Fuji Duet was significantly higher than CB Metabond, Panavia 21, and Cerec Duo but was not significantly higher than EnForce.

This in vitro study evaluated the survival rate and fracture resistance of maxillary central incisors restored with different post and core systems. The post and core systems investigated were a prefabricated high precious metal post with cast core (group A), zirconia post with a prefabricated bonded ceramic core (group B), and a resin-ceramic interpenetrating phase composite post (experimental) with a prefabricated bonded ceramic core (group C). The all-ceramic copings were cemented using Panavia 21 TC. In the group without coronoradicular reinforcement, the access cavity was closed with a light-cured composite in combination with a dentine-bonding agent (group D). Each specimen was intermittently loaded and thermocycled before final stress tests in a Zwick machine. The survival rates after 1,200,000 cycles in the artificial mouth were 90% (group A), 80% (group B), 60% (group C), and 100% (group D). Statistically significant differences were found between all groups with the exception of A and B, when failure during cyclic loading was included (Kruskal-Wallis multiple comparisons test). Samples restored with a cast post and core demonstrated more vertical root fractures. It was concluded that the preservation of both internal and external tooth structure is of utmost importance when restoring endodontically treated teeth.

Many endodontic sealers contain constituents that have been shown to inhibit the polymerization of resin cements. This may be important when prefabricated posts are cemented at the same appointment as root canal obturation. This study evaluated the effects of cementing posts with a resin cement immediately or at a delayed time period after obturation using Roth's 801 Elite Grade or AH26 sealer cements. The contribution of mechanical post-space preparation was also assessed as a critical variable. One hundred twenty extracted canines were randomly divided into eight experimental groups. The variables evaluated were the order of post preparation (either before or after obturation), the type of sealer used, and the time of post cementation. All teeth received a stainless steel #6 Parapost XP cemented with a resin cement, Panavia 21. Each experimental group underwent tensile testing for retention using an Instron universal testing machine. For both sealers posts cemented in teeth in which the canal was obturated before post-space preparation and thus had sealer-contaminated dentin removed by the space preparation procedure had significantly higher retentive values than those obturated after post-space preparation in which contaminated dentin might remain. Sealer used and time of cementation had no specific effect on retention. Achieving a clean, “freshened” den-tinal surface during mechanical post-space preparation seems to be a critical variable for post retention when a resin cement is used.

The purpose of this study was to test the feasibility of adapting a new microtensile testing technique to measure resin cement bond strengths to the cervical, middle, and apical thirds of root canals. Post spaces were created in extracted human teeth, and the roots were ground flat on one side to expose the canal and permit ideal placement of one of two resin cements (Panavia 21 or C&B Metabond). After 48 h of storage, serial 1-mm-thick cross-sections were cut to create 6-10 specimens per root. The first three specimens were from the cervical third, the next three were from the middle third, and the last three were from the apical third of the root. Each 1 x 1 x 8 mm specimen was pulled to failure in a miniature testing machine. The results indicated that both resin cements produced high bond strengths (12-23 MPa), and that bond strengths to the apical third were significantly higher (p < 0.05) than to the cervical or middle third with either cement. This new method shows promise for evaluating resin bond strengths within root canals.

The present study investigates the influence of the pulpotomy agent formaline cresol (FC) on bond strength between dentin and five adhesive systems (Super-Bond C&B, Bistite II, Imperva Dual Set, Panavia 21, and Panavia 21 with AD Gel). After the dentin surfaces of 75 bovine teeth (including 25 control samples) were exposed by grinding, 25 of the samples were soaked in FC for 2 days, and 25 samples were soaked for 7 days. Samples were bonded to acrylic rods using five adhesive systems, and tensile bond strengths were determined after 1-day immersion in water. Data were analysed by analysis of variance and Duncan's new multiple range test, and the fractured surfaces were observed through a scanning electron microscope. The bond strengths were found to be influenced by the type of system, soaking period, and their combination. The bond strength values of three adhesive systems (Super-Bond C&B, Imperva Dual Set Bistite II, and Panavia 21 with AD Gel) decreased after soaking in FC. After 7 days of FC exposure, the highest bond strength (9.8+/-2.9 MPa) was obtained with the Super-Bond C&B system.

Purpose. This study: (1) tested 2 BIS-GMA resinous cements on tinplated gold alloy surfaces with shearing forces to record their bond strengths, and (2) determined whether storage of the tinplated surfaces in water before cementation affected initial bond strengths. Material and methods. The bond strengths of Panavia Ex and Panavia 21 resinous cements to tinplated Type III gold alloy were measured when subjected to shearing forces. Specimens were luted in pairs with these cements. In one group, the cementation was performed after tinplating procedures. In the other group, tinplated alloy surfaces were first stored in water at 37°C for 48 hours before cementation. Results. A 3-fold increase in bond strength values was recorded for tinplated specimens stored in water before cementation with both cements; these differences were statistically significant. Storage of the specimen in water before cementation appeared to increase resistance of the alloy-resin bond to failure with application of shearing forces. Conclusion. This pilot study suggested that it would be advantageous to age tinplated gold alloy surfaces in water for 48 hours before cementation. (J Prosthet Dent 1998;80:302-6.)

This study evaluated the microleakage and interfacial micromorphology of Class V cervical amalgam restorations lined with OptiBond, AElitebond, or Panavia 21.Unlined amalgams served as control. Cavities were treated with each dentin bonding system according to the manufacturers' instructions and restored with Tytin non-gamma 2 spherical amalgam. After one week of storage in tap water at 37 degrees C, the specimens were thermocycled (1000 cycles, 6-60 degrees C, 30s dwell time). Microleakage was assessed by means of basic fuchsin dye penetration and recorded according to an ordinal scale.None of the systems tested in this study completely eliminated microleakage. Kruskal-Wallis one-way ANOVA and Mann-Whitney U test found that on the occlusal wall, Panavia 21 and the control group had the least leakage (P0.05). No statistically significant differences were found at dentin margins (P0.05). Wilcoxon matched pairs signed rank test found that Panavia 21 and the control group had less leakage at the occlusal than at the dentin margins (P0.05); when AElitebond and OptiBond groups were evaluated, microleakage at the enamel and at the dentin margins was similar for each group. With the adhesive systems, perhaps the hydrophilic bonding agents incorporated the dye during specimen immersion and/or sectioning.The use of adhesives may not be as worthy as resin cements for sealing and bonding amalgam restorations to enamel and dentin.