In vitro comparative bond strength of contemporary self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion.

This study compared shear bond strengths of six self-adhesive resin cements to zirconium oxide ceramic with and without air-particle abrasion. One hundred twenty zirconia samples were air-abraded (group SB; n = 60) or left untreated (group NO). Composite cylinders were bonded to the zirconia samples with either BisCem (BC), Maxcem (MC), G-Cem (GC), RelyX Unicem Clicker (RUC), RelyX Unicem Applicator (RUA), or Clearfil SA Cement (CSA). Shear bond strength was tested after thermocycling, and data were analyzed with analysis of variance and Holm-Sidak pairwise comparisons. Without abrasion, RUA (8.0 MPa), GC (7.9 MPa), and CSA (7.6 MPa) revealed significantly higher bond strengths than the other cements. Air-particle abrasion increased bond strengths for all test cements (p < 0.001). GC (22.4 MPa) and CSA (18.4 MPa) revealed the highest bond strengths in group SB. Bond strengths of self-adhesive resin cements to zirconia were increased by air-particle abrasion. Cements containing adhesive monomers (MDP/4-META) were superior to other compositions.

Symmetry of horizontal and sagittal condylar path angles: an in vivo study.

The specific aims of the study were to determine (1) the mean condylar path inclination (CP) and Bennett angles (BA) in occlusally healthy dentate subjects and (2) whether there was right-left asymmetry of CP and BA. Eccentric movements of three mm and five mm from reference positions were recorded for 45 subjects using a Cadiax system. The mean right CP angles: 48.8 +/- 8 degrees (three mm) and 48.2 +/- 7 degrees (five mm); the mean left CP angles: 48.8 +/- 8 degrees (three mm) and 49.5 +/- 70 (5mm) were steeper than suggested means for setting articulators. The mean right BA: 7.7 +/- 3 degrees (3mm) and 7.9 +/- 4 degrees (five mm); and the mean left BA: 8.1 +/- 4 degrees (three mm) and 8.5 +/- 4 degrees (five mm) were lower than suggested means for setting articulators. Paired-t-tests showed no significant differences between right-left CP and right-left BA. These results suggest that current recommended average settings for semi-adjustable articulators for dentate individuals need to be reassessed.

In vitro shear bond strength of dual-curing resin cements to two different high-strength ceramic materials with different surface texture.

OBJECTIVE: The purpose of this study was to evaluate the shear bond strength (SBS) of two dual-curing resin cements to two high-strength ceramics with different surface texture. MATERIAL AND METHODS: Composite cylinders were bonded to aluminum oxide (A) and zirconium oxide (Z) ceramic disks with six different surfaces. Investigated surfaces were for both ceramics: dry-pressed Procera Crown (A1, Z1), machined Procera Bridge (A2, Z2), airborne particle abraded Procera bridge (A3, Z3). Additional surfaces were, for alumina, dry-pressed Procera Laminate (A4) and, for zirconia, two modified surfaces (Z4, Z5). Two adhesive resin cements were used (Clearfil Esthetic and RelyX ARC). SBS was tested in a universal testing machine before and after artificial aging by thermal cycling. RESULTS: Mean SBS ranged from 6.1 to 38.4 MPa before and from 0.0 to 41.4 MPa after aging. Clearfil Esthetic in A3, A4, and Z3 performed better than RelyX ARC. Aging decreased SBS, except for Z1, Z4, and Z5. For alumina, A4 was higher in SBS than A2, but similar to A1 and A3. For zirconia, Z5 showed the highest SBS. Z4 was higher than Z2 and Z3, but similar to Z1. CONCLUSIONS: Shear bond strength to alumina and zirconia increases with surface roughness. The modified zirconia surface Z5 provides stable long-term shear bond strength and can be bonded to either of the two used cements.

Resin-bonded fixed partial dentures with a new modified zirconia surface: a clinical report.

This report describes the clinical application of a new modified zirconia surface. Resin-bonded fixed partial dentures were fabricated for nonprepared abutments, cemented, and evaluated for retention and esthetics. Initial evaluation of this new modified zirconia surface reveals acceptable mechanical and esthetic properties.

An in vitro evaluation of the long-term resin bond to a new densely sintered high-purity zirconium-oxide ceramic surface.

STATEMENT OF PROBLEM: Successful long-term bonding to zirconia ceramic remains a challenge, requiring special cements and surface roughening by airborne-particle abrasion, which might negatively affect the ceramic. PURPOSE: The purpose of this study was to evaluate the shear bond strength (SBS) of composite resin cylinders to a modified zirconia surface using different luting techniques after thermal cycling. MATERIAL AND METHODS: Composite resin (TPH3) cylinders with a diameter of 3 mm were bonded to zirconia ceramics (Procera Zirconia) with a modified surface (RZ) and a machined surface (MZ). Three different adhesive luting cements (Panavia F2.0, RelyX ARC, RelyX Unicem) in combination with and without airborne-particle abrasion (50-microm and 110-microm Al(2)O(3)) were used. RZ was bonded using all 3 cements with (50 mum) and without airborne-particle abrasion; with 110 microm, only Panavia F2.0 was used. MZ was bonded using only Panavia F2.0 with (50 microm, 110 microm) and without airborne-particle abrasion. SBS was tested in a universal testing machine (Instron) before and after 90 days of water storage and 20,000 thermal cycles (dwell time, 15 seconds). Statistical analysis was performed using a multifactorial ANOVA model with alpha=.05. RESULTS: Mean SBS ranged from 10.1 to 20.0 MPa after 3 days and from 0.16 to 14.8 MPa after thermal cycling. Thermal cycling decreased SBS significantly. Airborne-particle abrasion significantly decreased SBS to the modified surface, regardless of cements used. SBS to the modified zirconia surface was significantly higher than to the machined surface. CONCLUSIONS: SBS to the modified zirconia surface is higher than to airborne-particle-abraded, machined zirconia. Airborne-particle abrasion of the modified zirconia surface is not recommended.

The effect of immediate dentin sealing on the marginal adaptation and bond strengths of total-etch and self-etch adhesives.

STATEMENT OF PROBLEM: Sealing ability and bond strengths of total-etch and self-etch dentin adhesives used for immediate dentin sealing have not been assessed and established. PURPOSE: The purpose of this study was to determine the effectiveness of immediate dentin sealing (IDS) using total-etch or self-etch dentin adhesives on microleakage and microtensile bond strength. MATERIAL AND METHODS: Twenty recently extracted molars were selected, and standard MOD inlay preparations were made with the gingival margins located below the cemento-enamel junction. The teeth were assigned to 4 experimental groups (n=5) according to the indirect composite restoration cementation technique used: (1) immediate dentin sealing with Adper Single Bond (TEBI); (2) conventional adhesive cementation technique using Adper Single Bond (TEAI); (3) immediate dentin sealing using Adper Prompt L-Pop (SEBI); or (4) conventional adhesive cementation technique using Adper Prompt L-Pop (SEAI). The restored teeth were thermal cycled 1,000 times between 5 degrees and 55 degrees C and then immersed in 50% ammoniacal silver nitrate. Three specimens per restoration were evaluated for microleakage, according to predefined scores, and submitted to Friedman's test (alpha=.05). The specimens were then sectioned to obtain 0.8 +/-0.2-mm-thick sticks (with n ranging from 32 to 57 specimens) and submitted to microtensile bond strength (muTBS) testing. The obtained data were submitted to 2-way ANOVA test (alpha=.05). RESULTS: None of the experimental groups demonstrated complete elimination of marginal microleakage. There were significant differences in microleakage of the tested adhesives (P>.001). IDS microleakage scores were similar to those obtained using the conventional cementation technique (CCT) for both adhesives. The highest mean bond strengths were obtained with TEBI (51.1 MPa), whereas SEAI showed the lowest mean bond strengths (1.7 MPa). IDS resulted in significantly higher bond strengths than CCT (P<.001). CONCLUSIONS: Total-etch and self-etch adhesives have a significant effect on IDS. IDS resulted in high bond strengths for both adhesives; however, the microleakage was similar to that obtained with CCT. (J Prosthet Dent 2009;102:1-9).

Shade-matching abilities of dental laboratory technicians using a commercial light source.

PURPOSE: The purpose of this study was to evaluate dental laboratory technicians' abilities to match shades using a light-corrective device under conventional laboratory conditions. The variables measured were years experience, gender, and light source. MATERIALS AND METHODS: A 14-item shade-matching quiz (SMQ) was field-tested and deemed adequate. Information included age, gender, number of years experience, and Ishihara's Colour-Blindness Assessment. Forty-two dental technicians from five northeast Ohio laboratories were invited to participate. The SMQ was administered twice: under the lighting conditions in the individual laboratories (SMQ-Lab) and with a light-corrective source (SMQ-LC). For each item, the technicians were to select the matching Vita shade tab from five preselected shade tabs. SMQ scores equaled the number of correct matches. Statistical analysis included calculation of means, standard deviations, correlation coefficients, and independent and paired t-tests. Significance was set at p

Microtensile bond strengths and scanning electron microscopic evaluation of self-adhesive and self-etch resin cements to intact and etched enamel.

STATEMENT OF PROBLEM: The longevity of indirect adhesively cemented restorations is directly related to the bond quality of resin cements to dental tissues. Bonding to cervical enamel can generate significantly lower bond strengths than bonding to other enamel areas. The effect of enamel pretreatment on bond strengths of self-etch and self-adhesive resin cements to cervical enamel remains undetermined. PURPOSE: The purpose of this study was to evaluate cervical enamel bond strengths of self-adhesive, self-etch resin cements according to acid pretreatment, using a total-etch resin cement as the control. MATERIAL AND METHODS: The proximal surfaces of 20 extracted molars were sectioned to obtain 40 enamel rectangles with an area of 8.0 x 4.0 mm. The rectangular enamel specimens were assigned to 1 of 5 enamel experimental groups: intact enamel + RelyX Unicem (UN), etched enamel + UN (UNpa), intact enamel + Multilink (ML), etched enamel + ML (MLpa), and the total-etch-based RelyX ARC (RX; control group). Standard 8.0 x 4.0 x 6.0-mm composite resin blocks (Z250) were cemented to all specimens. The bonded enamel surfaces were sectioned into sticks with a cross-section of 0.8 +/-0.2 mm(2) and tested to failure in tension mode at a crosshead speed of 1 mm/min. The data were submitted to 1-way analysis of variance (ANOVA), followed by Tukey's HSD post hoc test (alpha=.05). Additionally, the enamel etching pattern was investigated for all experimental groups using field-emission electron microscopy. RESULTS: Statistical analysis showed significant differences among different resin cements (P<.001) and phosphoric acid etching (P<.002). The highest mean (SD) bond strengths were obtained with UNpa (32.92 (4.23)) > RX (19.40 (9.47)). Acid etching of enamel before application of self-etch resin cement did not improve the mean bond strengths (SD) for self-etch resin cement [ML (5.38 (5.97)); MLpa (5.23 (1.1))]. Self-adhesive and self-etch resin cements yielded the lowest significant mean bond strengths (SD) when applied on intact enamel: UN (13.03 (2.82)) > ML (5.38 (5.97)). Scanning electron microscopy showed a consistent etching pattern for phosphoric acid-etched specimens. Self-etch and self-adhesive resin cements applied directly to intact enamel showed inconsistent areas of etching. CONCLUSIONS: Etching cervical enamel surfaces resulted in significantly higher bond strengths for self-adhesive resin cement. For self-etch resin cement, etching did not improve bond strength.

The pier abutment: a review of the literature and a suggested mathematical model.

Many clinicians consider the prosthetic restoration of missing posterior teeth by means of a 5-unit fixed partial denture with a pier abutment a non-favorable situation. The present article assesses the validity of the pier abutment by means of a critical review of the literature and mathematical analysis of the forces generated within a fixed partial denture of this design. Few studies are available, and none substantiate the theory that the pier abutment serves as a fulcrum. A mathematical model suggests that debonding may occur in the anterior abutment, but not due to the teetering of the fixed partial denture around the pier abutment.

A conservative approach for the management of a crown-root fracture.

Subgingival crown-root fractures are major complications that jeopardize tooth survival and require the clinician to adopt a multidisciplinary approach combining different dental specialties to effectively treat the teeth and ensure long-term survival. Fragment reattachment is a conservative therapeutic option for uncomplicated crown-root fractures. However, biologic width involvement must be carefully evaluated and addressed. This article describes a case of restoration of a crown-root fracture by means of periodontal surgical exposure of the fracture, crown and root recontouring, and fragment reattachment.

Adhesive cementation of chairside CAD/CAM inlays and onlays.

Chairside CAD/CAM restorations offer aesthetic, functional, biocompatible, and long-term successful alternatives to traditional materials and techniques, and can be fabricated in one appointment. Adhesive cementation is key for the long-term clinical success of CAD/CAM inlays and onlays. The clinical use of a newly developed composite resin cement for adhesive cementation of CAD/CAM inlays/onlays has been described.

Clinical considerations for densely sintered alumina and zirconia restorations: part 2.

Part 1 of this series provided the foundation for understanding the nature of densely sintered alumina- and zirconia-based restorations, provided guidelines for case selection, and addressed framework design considerations. This article discusses guidelines for lamination of the densely sintered alumina- and zirconia-based restorations and proper try-in, and examines options for conventional and adhesive luting procedures.

Clinical considerations for densely sintered alumina and zirconia restorations: Part 1.

Densely sintered alumina- and zirconia-based restorations were introduced to dentistry in the early 1990s and became a popular treatment modality, especially in situations requiring complete-coverage restorations. The use of industrial technologies for the fabrication of the restoration, simple clinical management, and pleasing esthetic outcome have made these restorations an attractive treatment alternative. This article reviews the nature of the materials used and the technologies involved and provides indications for clinical case selection and tooth preparation.

Selected characteristics of a new polyvinyl siloxane impression material--a randomized clinical trial.

OBJECTIVES: This study evaluated the ability of a new polyvinyl siloxane impression material (Affinis, Coltène/Whaledent, material A) to obtain final impressions free of bubbles and voids for indirect fixed cuspal-coverage restorations. The results were compared to a control polyvinyl siloxane impression material (material B). Both materials were handled by inexperienced clinicians (undergraduate dental students) in student clinics. METHOD AND MATERIALS: One-hundred and thirty patients who were treated in the Louisiana State University School of Dentistry Junior Student Clinic for indirect fixed cuspal-coverage restorations and who met the inclusion criteria were randomly assigned to either one of two treatment groups, group A (n = 65) or group B (n = 65). Two calibrated examiners evaluated the first impression of prepared posterior teeth at a magnification of 10x for acceptability (no voids or bubbles). Position of tooth, type of preparation, preparation finish line (Class I-V), and gingival bleeding scores were recorded. All statistical tests were performed with the level of significance set at .05. RESULTS: The Fisher-Freeman-Halton test did not reveal significant associations between material and gingival bleeding score (P = .492). Significant differences in the location of the preparation finish line between materials were observed (P = .0096); material A was more frequently used in cases where the preparation finish line was located at least 2 mm subgingivally. Logistic regression was used to assess the effect of the material on the success of the impression (acceptable/ unacceptable). Material was highly significant in the logistic model (P < .001) with an odds in favor of an acceptable impression being eight times higher with material A than with material B (odds ratio = 8.00; 95% confidence index for odds ratio: 2.832, 22.601). The 60/65 (92.3%) impressions made with material A and 39/65 (60%) impressions made with material B were rated "acceptable." CONCLUSION: The new polyvinyl siloxane impression material provided a significantly higher proportion of impressions free of bubbles and voids than the control polyvinyl siloxane material.

Hydrophilic vinyl polysiloxane impression materials.

VPS impression materials that contain a surfactant cannot be considered as hydrophilic, rather they are probably less hydrophobic. More VPS products that contain surfactants are expected to be introduced to the market. It is yet to be proven that surfactant-containing VPS materials have a better wettability than polyether-based impression materials. The current data still indicates that polyethers are more hydrophilic. The less hydrophobic behavior of the surfactant-containing VPS may provide a significant advantage in clinical practice. Due to this advantage, the author suggests that clinicians using VPS as their preferred elastomeric impression material should consider switching to surfactant-containing VPS impression materials.

In vitro durability of the resin bond to feldspathic ceramics.

PURPOSE: To measure and compare shear bond strength of three different resin-based composite cements (Panavia 21, Noribond DC, and Variolink II) to two feldspathic ceramic materials (Noritake EX-3 and Ceramco) after 3 days (at baseline) and after 180 days of water storage and repeated thermocycling. METHODS: Composite cylinders were bonded with Panavia 21, Noribond DC, and Variolink II to the hydrofluoric acid (HF)-etched surfaces of either Noritake Super Porcelain EX-3 (NEX) or Ceramco (CER) following the manufacturers' directions. Subgroups of 15 specimens were stored in distilled water for either 3 days without thermocycling or 180 days with 12,000 thermal cycles. Shear bond strength was measured and compared by loading each specimen in shear to failure in an Instron testing system. Data were analyzed with a three-factor ANOVA model. Post-hoc multiple comparisons of the individual main-effect levels were performed with Tukey's HSD multiple comparison procedure (alpha = 0.05). RESULTS: Mean bond strength did not differ for the two ceramic materials. Differences in mean bond strength were found among the bonding systems and between the early and late time points. Panavia exhibited significantly lower bond strength as compared to Noribond and Variolink II for both early and late time points, with a greater difference at 180 days. For all groups, failure modes were almost exclusively cohesive in the ceramic, which indicates sufficient resin-ceramic bonds with all tested materials.

Influence of silanization on early bond strength to sandblasted densely sintered alumina.

OBJECTIVE: The increased popularity of alumina-based restorations has resulted in an interest in proper adhesive techniques to assure a strong and predictable bond to these restorations. This study investigated the early bond strength of three different resin-cement systems to densely sintered alumina (aluminum-oxide ceramic) with and without the use of their corresponding silane coupling agent (silanization). METHOD AND MATERIALS: Ninety samples of densely sintered high-purity aluminum-oxide ceramic were randomly divided into three groups. Composite cylinders were bonded to the ceramic samples with three resin-cement/bonding-agent systems: Noribond DC (NOR), Panavia 21 EX (PAN), and Variolink II (VAR). Each resin-cement/bonding-agent system was used with and without their corresponding silane (SIL) coupling agent (n = 15). After fabrication, the specimens were stored in distilled water for 3 days at room temperature, and shear bond strength was tested. RESULTS: Application of the silane-coupling agent on sandblasted densely sintered alumina did not significantly influence bond strengths with PAN. Silanization significantly improved shear bond strengths with NOR and VAR. NOR-SIL and VAR-SIL revealed the statistically highest values, with NOR-SIL showing the highest mean bond strength of all groups. CONCLUSIONS: Silanization of sandblasted densely sintered alumina had mixed effects on the applied resin cements: It had no effect on the performance of the phosphate-modified resin cement PAN, but significantly improved shear bond strength of the Bis-GMA composite resin cements VAR and NOR. NOR-SIL revealed the highest overall mean bond strength.

The effect of silica coating on the resin bond to the intaglio surface of Procera AllCeram restorations.

OBJECTIVES: This study investigated the influence of a silica-coating method on the resin bond of two different resin composite cements to the intaglio surface of Procera AllCeram densely sintered, high-purity, alumina ceramic restorations after long-term storage and thermocycling. METHOD AND MATERIALS: Densely sintered alumina ceramic specimens were fabricated with the intaglio surface of the Procera AlICeram coping and randomly divided into five adhesive groups (100 total specimens). Resin composite cylinders were bonded either to the untreated or to the tribochemical silica/silane-coated ceramic surface with either a conventional Bis-GMA resin cement or a resin composite containing an adhesive phosphate monomer (Panavia 21) in combination with their corresponding bonding/silane coupling agents. Panavia was also used without silanization to the untreated ceramic surface (control). Subgroups of 10 specimens were stored in distilled water for either 3 (baseline) or 180 days prior to shear bond strength testing. The 180-day samples were subjected to repeated thermocycling for a total of 12,000 cycles. Data were analyzed with one-way analysis of variance and Tukey's multiple comparison. RESULTS: Silica coating significantly increased overall bond strength to Procera AllCeram. RelyX ARC and silica coating revealed the highest bond strength at baseline. Long-term storage and thermocycling significantly decreased overall bond strength. Two groups revealed the significantly highest bond strength values after artificial aging: Panavia 21 with its silane/bonding agent to the original ceramic surface and Panavia 21 to the silica-coated ceramic surface. CONCLUSION: The use of a resin composite containing an adhesive phosphate monomer either in combination with a silane coupling/bonding agent or after tribochemical silica/silane coating revealed the highest long-term shear bond strength to the intaglio surface of Procera AllCeram restorations.

Post placement and cementation: Part 1.

Premolars can be considered as a separate entity in the category of root canal treated teeth that will receive a full-coverage restoration. Their unique morphology and their susceptibility to high occlusal load, as well as contemporary preparation guidelines that advocate a wide shoulder finish line design will necessitate the placement of a post in the majority of premolars. Although some of the remaining thin walls will be eliminated during preparation, their removal is not recommended prior to the buildup procedure. Any remaining wall structure can provide additional ferrule and serve as an anti-rotation mechanism.

Post placement and cementation: Part 2.

In situations with thin remaining root walls, the clinician should not attempt to place an extremely wide post that will engage the canal walls. Rather, the practitioner should use a thinner post and a resin cement that will create a custom-fitted, cement-post complex.