Effect of an antibacterial adhesive on the bond strength of three different luting resin composites

OBJECTIVES: Effect of a dentin adhesive system containing antibacterial monomer-MDPB (Clearfil Protect Bond) on the shear bond strength of all-ceramic-IPS Empress 2 restorations luted with three different dual-polymerizing systems (Variolink 2, RelyX ARC and Panavia F 2.0) to dentin was investigated. METHODS: One hundred and eight all-ceramic discs (2 x 3mm; IPS Empress 2) were fabricated and ultrasonically cleaned. The buccal surfaces of 108 non-carious extracted human premolars were flattened to expose dentin and subsequently polished with 600-grit wet silicon carbide paper. Three dual-polymerizing luting systems had test groups and control groups consisting of 18 samples each. For the test groups Clearfil Protect Bond was applied to the exposed dentin surfaces. Control groups received the original bonding procedures of each adhesive system. After the all-ceramic samples were luted to the teeth, thermocycling was performed 5000 times. Shear bond strengths were tested using Shimadzu Universal Testing Machine until failure. Analysis of fractured dentin surfaces were performed using Optical Microscope at x10 and x1000 magnifications and the images were analyzed with Image Analyzer. Data was analyzed with one-way ANOVA and Bonferroni test at a significance level of p<0.05. RESULTS: Mean shear bond strength data of the groups in MPa were; Variolink: 20.45+/-4.75, Variolink+Clearfil Protect Bond:29.32+/-2.37, RelyX ARC:18.82+/-3.19, RelyX ARC+Clearfil Protect Bond:25.58+/-4.05, Panavia F 2.0:17.11+/-2.98, Panavia F 2.0+Clearfil Protect Bond:24.40+/-7.46. Application of the antibacterial adhesive increased the shear bond strengths of all three dual-polymerizing systems to dentin (p=0.00). The surface analysis showed that most of the specimens showed the adhesive failure mode between the dentin and the composite luting agent interface. CONCLUSION: The antibacterial adhesive system Clearfil Protect Bond can be safely used to prevent the potential risk of complications resulting from bacterial activity regardless of affecting the bond strength of IPS Empress 2 restorations luted with the dual-polimerizing systems used in this study.     

Fiber‐post bond strength in canals obturated with a cross‐linked gutta‐percha core obturator

The aim of this in‐vitro study was to evaluate the bond strength of fiber posts cemented in a root canal filled using various root‐canal obturation techniques. A total of 33 monoradicular samples, treated endodontically, were randomly assigned to three groups according to the root‐canal obturation technique: group 1, continuous‐wave technique; group 2, plastic‐obturator‐core technique; and group 3, cross‐linked gutta‐percha obturator‐core technique. Fiber posts were luted in each sample and each was sectioned perpendicular to the post axis. The push‐out test was performed using a universal machine and the maximum failure load was recorded in MPa mm^?2. Several samples were randomly chosen for scanning electron microscopy evaluation. The mean debris and dentinal tubule‐opening scores were calculated separately in the coronal and apical portions. Bond strength was significantly higher in group 1 than in groups 2 and 3. Debris scores were significantly higher in the apical portion of groups 2 and 3 than in group 1. Within the limitations of this study it can be affirmed that thermoplasticized alpha gutta‐percha seemed to worsen the cleaning of post‐space walls and hence reduced fiber‐post bond strength.     

The effect of different adhesive system applications on push-out bond strengths of glass fiber posts

PURPOSE

Over the past years, the adhesion of fiber posts luted with simplified adhesive systems has been a matter of great interest. The aim of this study was to assess the post retentive potential of a self-adhesive resin cement using different adhesive systems to compare the push-out bond strengths of fiber posts.

MATERIALS AND METHODS

The post spaces of 56 mandibular premolar roots were prepared and divided into 4 experimental groups and further divided into 2 subgroups according to testing time (n=7). The fiber posts (Rely X Fiber Post) were luted with a self-adhesive resin cement (RelyX Unicem) and one of the following adhesive systems: no adhesive, a total-etch adhesive resin (Single Bond), a two-step self-etch adhesive resin (Clearfil SE Bond) and a one-step self-etch adhesive resin (Clearfil S3 Bond). Each root was cut horizontally, and 1.5 mm thick six root segments were prepared. Push-out tests were performed after one week or three months (0.5 mm/min). Statistical analysis were performed with three-way ANOVA (α=.05).

RESULTS

Cervical root segments showed higher bond strength values than middle segments. Adhesive application increased the bond strength. For one week group, the total-etch adhesive resin Single Bond showed higher bond strength than the self-adhesive resin cement RelyX Unicem applied without adhesive resin at middle region. For 3 months group, the two-step self-etch adhesive resin Clearfil SE Bond showed the highest bond strength for both regions. Regarding the time considered, Clearfil SE Bond 3 months group showed higher bond strength values than one week group.

CONCLUSION

Using the adhesive resins in combination with the self-adhesive resin cement improves the bond strengths. The bond strength values of two-step self-etch adhesive resin Clearfil SE Bond improved as time passes.     

Influence of eugenol on the push-out bond strengths of fiber posts cemented with different types of resin luting agents

This study evaluated the influence of eugenol on the push-out bond strengths of fiber posts cemented with different types of resin luting agents. Seventy-two extracted maxillary single-rooted canine teeth were randomly divided into two groups of 36 teeth. Group 1, the control group, was filled with gutta-percha only (i.e., did not receive eugenol), whereas group 2 was filled with a eugenol-containing sealer. All root canals were filled and each group was divided into three subgroups. The posts in each subgroup were cemented with the following materials: subgroup 1 with a 2-step self-etching adhesive system (Clearfil Liner Bond 2V + Panavia F); subgroup 2 with a 1-step self-etching adhesive (Panavia F); and subgroup 3 with a self-adhesive (Clearfil SA Cement). Dislodgement resistance was measured using a universal testing machine. All data were subjected to ANOVA using a factorial design and Tukey test (α = 0.05). The use of the eugenol-containing sealer significantly reduced the push-out bond strength of the fiber post (P < 0.05). The push-out bond strength of Panavia F was significantly higher than those of the other groups filled with the eugenol-containing sealer (P < 0.05). The Panavia F group was less susceptible to the inhibiting effect of eugenol than were the other evaluated groups when the fiber post was cemented in the canals filled with the eugenol-containing sealer.     

Influence of cement type and ceramic primer on retention of polymer-infiltrated ceramic crowns to a one-piece zirconia implant

Statement of problem

The best procedure for cementing a restoration to zirconia implants has not yet been established.

Effect of adhesives on bond strength of porcelain veneer to base metal alloy.

OBJECTIVE: The purpose of this in vitro study was to evaluate the bond strength of porcelain veneer to base metal alloy using different adhesive systems. METHOD AND MATERIALS: Eighty cylindrical models were cast in a nickel-chromium-beryllium base metal alloy. After they were mounted in self-cured acrylic resin, the surfaces of the specimens were air abraded. Specimens were divided into four groups of 20. Control porcelain disks were baked on the base metal. For the experimental groups, 60 porcelain disks were made. After 50-microm aluminum oxide sandblasting, a silane coupling agent was applied to the surface of the porcelain. The experimental groups were based on the type of adhesive used to bond porcelain to metal: Scotchbond Multipurpose and Duo Cement; One Coat Bond and Duo Cement; or Panavia 21 Ex. After 500 thermal cycles, the bonded porcelain specimens were placed under a continuous shear load of 2 mm/min until fracture occurred. RESULTS: Mean values for bond strength were 25.39 (control), 19.10 (Panavia 21 Ex), 15.81 (Scotchbond Multipurpose), and 13.69 MPa (One Coat Bond). Statistically significant differences in bond strength were noted between the control group and all the experimental groups. A statistically significant difference was observed between Panavia 21 Ex specimens and One Coat Bond specimens. CONCLUSION: Panavia 21 Ex provided an effective bond strength between a porcelain veneer and a base metal alloy, the closest of all the experimental groups to that of the control group.     

The effect of application sustained seating pressure on adhesive luting procedure.

OBJECTIVES: To evaluate the effect of short versus long application seating pressure on the bond strength of resin blocks, luted with a dual-cured resin cement (Panavia F) to pre-coated or non pre-coated dentin with an hydrophobic light-cured adhesive (Clearfil Protect Bond). METHODS: Sixteen non-carious human third molars were randomly divided into six Groups (four teeth each). Cylindrical composite blocks were luted with Panavia F (Group Ia) and with Clearfil Protect Bond with Panavia F (Group IIa) and seating pressure was applied for 5s. In Groups Ib and IIb, the two bonding procedures were respectively repeated, but the resin cylinder was maintained under constant pressure during the entire 3min polymerization period for the resin cement. After storing in distilled water for 24h, 0.9mmx0.9mm sticks were produced from these luted specimens for microtensile bond testing and SEM examination. RESULTS: The use of Clearfil Protect Bond with Panavia F produced higher bond strengths than the use of Panavia F (p<0.05). Extending the time of pressure application up to 3min increased the bond strength (p<0.001) and improved the integrity of the interfacial quality. SIGNIFICANCE: The application of sustained seating pressure during luting procedures and the additional use of a hydrophobic light-cured adhesive both improve the final bond strength of the resin cement.     

Influence of dentin bonding agents and polymerization modes on the bond strength between translucent fiber posts and three dentin regions within a post space

STATEMENT OF PROBLEM: Debonding is the most frequent failure encountered with translucent fiber posts and usually occurs along the post space dentin-adhesive interface. PURPOSE: The purpose of this study was to evaluate the effect of different dentin bonding agents and polymerization modes on the bond strength between translucent fiber posts and root dentin in different regions of the post space. MATERIAL AND METHODS: Forty maxillary canines with similar root lengths were selected, sectioned at the cemento-enamel junction, and the roots were endodontically treated. Following post space preparation, the roots were divided into 4 groups of 10 specimens each, and the post spaces were treated with 1 of 4 different dentin bonding agents: light-polymerized, single-bottle bonding agent Excite (Group EX); dual-polymerized, single-bottle bonding agent Excite DSC (Group EX-DSC); self-etching primer Clearfil Liner Bond 2V with a light-polymerized bonding agent, Bond A (Group CL-LC); or self-etching primer Clearfil Liner Bond 2V with a dual-polymerized bonding agent, Bond A+B (Group CL-DC). Translucent fiber posts (D.T. Light-Post), 2.2 mm in diameter, were luted (Panavia F) in each specimen after respective dentin bonding procedures. The roots were cut into 3-mm-thick sections, perpendicular to the long-axis in cervical, middle, and apical post space dentin. Push-out tests were performed with a universal testing machine at a crosshead speed of 0.5 mm/min, and bond strength values (MPa) were calculated by dividing the force at which bond failure occurred by the bonded area of the post. The data were analyzed with 1- and 2-way analysis of variance and Tukey multiple comparison tests (alpha=.05). Dentin adhesive bonding mechanisms in different regions of the post spaces were evaluated with a scanning electron microscope. RESULTS: The highest mean bond strength values were obtained for Group CL-LC (18.3 +/- 4.1 MPa). The dual-polymerized bonding agent resulted in significantly lower bond strength (P<.001) in combination with self-etching primer (Group CL-DC) (13.2 +/- 2.5 MPa). The light-polymerized and dual-polymerized single-bottle bonding agents provided similar bond strengths (12.7 +/- 5.0 for EX; 13.5 +/- 5.3 for EX-DSC). The regional bond strength values of single-bottle bonding agents were reduced significantly in apical post space dentin (P<.001). Self-etching primers did not demonstrate regional differences in post space dentin bonding and dense resin tags were apparent. CONCLUSION: Data suggests that the self-etching primer system used in this study was unaffected by the morphological variations in the post space dentin compared to the single-bottle bonding agents. Dual polymerization did not improve the bond strength values of the bonding agents tested.     

Influence of endodontic post type (glass fiber, quartz fiber or gold) and luting material on push-out bond strength to dentin in vitro.

OBJECTIVES: To determine the influence of post type and luting material on bond strength to dentin. METHODS: The root canals of extracted human upper central incisors were instrumented and post space was prepared using the respective drills for each post system. Glass fiber posts (Luscent Anchor, Dentatus [LA]) were luted using three dual-curing adhesive systems (Excite DSC/Variolink II, Vivadent [VL2]; EnaBond/EnaCem, Micerium [ENA]; Prime & Bond NT/Calibra, DentSply DeTrey [CAL]). A different brand of glass fiber post (EasyPost, DentSply Maillefer [EP]) and quartz fiber post (DT Light Post, VDW [DT]) were luted using CAL. Gold posts (Perma-dor, VDW) were luted either adhesively following tribo-chemical silicate coating (Rocatec, ESPE-Sil, 3M ESPE; CAL) or conventionally using glass ionomer cement (Ketac Cem, 3M ESPE). Three slices of 2mm height were cut perpendicular to the post from each restored root. Bond strength was determined by pushing out the post using a universal testing machine (/1449, Zwick). RESULTS: For all experimental groups combined, bond strength increased from the coronal to the apical section (Friedman test: P<0.001). Significant differences were observed among the fiber posts (DT/CAL>LA/CAL; Mann-Whitney U-test with Bonferroni-Holm adjustment: P<0.05; EP/CAL ranging in between) but not among luting materials (LA/VL2, LA/ENA, LA/CAL: n.s.). The gold posts were equivalent to DT/CAL with both luting procedures. SIGNIFICANCE: Selection of post type may be more important for bond strength than luting material. Bond strength of fiber posts was equivalent but not superior to adhesively or conventionally luted gold posts.     

Effect of a 12‐methacryloyloxy‐dodecyl‐pyridinium‐bromide–containing adhesive with different post types on the long‐term bond strength to dentin

The use of matrix metalloproteinase (MMPs) inhibitors, such as 12‐methacryloyloxy‐dodecyl‐pyridinium‐bromide (MDPB), might improve the adhesion of glass‐fiber (GF) and polyfiber (PF) posts to root dentine. This study assessed the effect of an MDPB‐containing adhesive on the long‐term bond strength of GF or PF posts to bovine dentine. Bovine endodontically treated roots were randomly divided into six groups, according to the post type and adhesive system used, as follows: GF serrated post + MDBP‐free adhesive; GF serrated post + MDPB‐containing adhesive; GF smooth post + MDBP‐free adhesive; GF smooth post + MDPB‐containing adhesive; PF post + MDBP‐free adhesive; PF post + MDPB‐containing adhesive. Specimens were stored in water for 6 months, thermocycled (500 cycles wk^?1), and submitted to the pull‐out test and failure pattern analysis. The cement–dentin interface was evaluated using scanning electron microscopy. The pull‐out data were analyzed using anova and Tukey's test (α = 0.05). No significant interaction between the type of post and the adhesive system was found. Polyfiber posts showed lower bond strength than GF posts, whether serrated or smooth, and the bond strength of the serrated and smooth GF posts was not significantly different. Adhesive failures were predominant in all groups. The type of retainer influenced the bond strength, and MDPB‐containing adhesive did not improve the long‐term bond strength of posts to dentine.     

Relationship between mechanical properties and bond durability of short fiber‐reinforced resin composite with universal adhesive

The purpose of this study was to determine the relationship between mechanical properties and bond durability of short fiber‐reinforced resin composite with universal adhesive. As controls, micro‐hybrid and nano‐hybrid resin composites were tested. The universal adhesives used were Scotchbond Universal, Adhese Universal, and G‐Premio Bond. The fracture toughness and flexural properties of resin composites, and shear bond strength and shear fatigue strength of universal adhesive with resin composite using both total‐etch and self‐etch modes were determined. In the results, short fiber‐reinforced resin composite showed significantly higher fracture toughness than did micro‐hybrid and nano‐hybrid resin composites. The flexural strength and modulus of short fiber‐reinforced and nano‐hybrid resin composites were significantly lower than were those of micro‐hybrid resin composites. Regardless of etching mode, the shear bond strength of universal adhesives with short fiber‐reinforced resin composite did not show any significant differences from micro‐hybrid and nano‐hybrid resin composites. The shear fatigue strength of universal adhesives with short fiber‐reinforced resin composite and micro‐hybrid resin composites were significantly higher than that of nano‐hybrid resin composites. The results of this study suggest that the mechanical properties of short fiber‐reinforced resin composite improve their bond durability with universal adhesive.     

Comparison between universal adhesives and two‐step self‐etch adhesives in terms of dentin bond fatigue durability in self‐etch mode

This aim of this study was to compare universal adhesives and two‐step self‐etch adhesives in terms of dentin bond fatigue durability in self‐etch mode. Three universal adhesives – Clearfil Universal, G‐Premio Bond, and Scotchbond Universal Adhesive – and three‐two‐step self‐etch adhesives – Clearfil SE Bond, Clearfil SE Bond 2, and OptiBond XTR – were used. The initial shear bond strength and shear fatigue strength of resin composite bonded to adhesive on dentin in self‐etch mode were determined. Scanning electron microscopy observations of fracture surfaces after bond strength tests were also made. The initial shear bond strength of universal adhesives was material dependent, unlike that of two‐step self‐etch adhesives. The shear fatigue strength of Scotchbond Universal Adhesive was not significantly different from that of two‐step self‐etch adhesives, unlike the other universal adhesives. The shear fatigue strength of universal adhesives differed depending on the type of adhesive, unlike those of two‐step self‐etch adhesives. The results of this study encourage the continued use of two‐step self‐etch adhesive over some universal adhesives but suggest that changes to the composition of universal adhesives may lead to a dentin bond fatigue durability similar to that of two‐step self‐etch adhesives.     

Effect of ethanol application on post-luting to intraradicular dentine

Aim  To examine the effect of the application of an ethanol rinse before luting fibre posts to intraradicular dentine with etch-and-rinse adhesive systems by means of push-out bond strength evaluation and scanning electron microscopic (SEM) analysis.
Methodology  Fibre posts were luted to single-canal premolars using Dual Link as a luting agent in combination with a three-step (All Bond 2) or a two-step (One Step Plus) etch-and-rinse adhesive system, which were applied as per manufacturers' instructions (control) or with the additional rinse of ethanol on acid-etched dentine prior to the bonding procedures (experimental). Bonded specimens were sectioned into 1-mm-thick slabs and subjected to push-out bond strength testing. In addition, specimens from each group were processed for SEM analysis. Data were analysed by Kruskal–Wallis followed by Dunn's post hoc test at P  = 0.05.
Results  Push-out bond strength of All Bond 2 was significantly increased if the adhesive was applied on ethanol-saturated dentine ( P  < 0.05), whilst no significant difference ( P  > 0.05) was detected amongst experimental and control groups for One Step Plus. Irrespective of the adhesive, the SEM analysis revealed good impregnation patterns when both bonding techniques were employed.
Conclusions  The use of the additional ethanol rinse on acid-etched dentine revealed higher bond strength of All Bond 2 when compared with the control application procedure, used in combination with a resin-based cement to lute fibre posts into the dowel space. However, no bond strength improvements were detected using One Step Plus. Further investigations are needed to develop a clinically applicable ethanol/bonding/luting technique.     

Effect of post‐space treatments on the push‐out bond strength and failure modes of glass fibre posts

The aim of this study was to evaluate the effect of different post‐space treatments on the push‐out bond strength and failure modes of glass fibre posts. Forty mandibular premolar roots were cut and endodontically treated. Post spaces were prepared and roots were divided into four groups. In group 1 distilled water irrigation (control), in group 2 2.25% NaOCl irrigation, in group 3 2.25% NaOCl + 17% EDTA irrigation were done and in group 4 diode laser was applied to the prepared post spaces. Scanning electron microscope (SEM) analysis was made for each group. Fibre posts were then luted with resin cement. Each root was prepared for push‐out test. Data were statistically analysed with anova (P = 0.05). After push‐out test, the failure modes were observed but not statistically analysed. There were statistically significant differences between Group 3 and Group 2 in both regions (P < 0.05), also in the middle region of Group 4 and Group 2 (P < 0.05). Cervical root segments showed higher bond strengths than middle ones in all groups (P < 0.05). The highest bond strength values were obtained from NaOCl/EDTA and the lowest bond strength values were obtained from NaOCl for both regions.     

Push‐out bond strength of an experimental self‐adhesive resin cement

The adhesion of fiber posts luted with simplified adhesive systems has been a matter of great interest over the past years. The aim of this study was to assess the post retentive potential of experimental self‐adhesive resin cement (EXP) when used alone and in combination with a self‐etch adhesive. Fiber posts were placed in endodontically treated teeth and divided into four groups (n = 6) according the luting material, as follows: group 1 (EXP alone); group 2 (EXP used with self‐etch adhesive); group 3 (marketed dual‐cured cement used with self‐etch adhesive); and group 4 (marketed self‐adhesive cement). The push‐out test was used to assess the retentive strength of fiber posts (expressed in MPa), and specimens were analyzed under a stereomicroscope to determine failure mode. The adhesive interface between the cement and root canal dentin for each group was evaluated using scanning electron microscopy. The post retentive potential of group 1 (EXP) (7.48 ± 4.35 MPa) was comparable with that of marketed cements from group 4 (6.79 ± 3.68 MPa) and group 3 (8.77 ± 4.58 MPa). When EXP was used in combination with self‐etch adhesive (group 2), significantly higher push‐out bond‐strength values were measured (15.87 ± 4.68 MPa) compared with the other groups.     

Effect of different bonding procedures on micro-tensile bond strength between a fiber post and resin-based luting agents

The purpose of this study was to evaluate the effect of silanization and light-irradiation on bonding between a fiber post and different resin-based luting agents. Sixty silicium fiber posts (Easy Post) were divided into 10 groups according to the type of resin-based luting agent employed, whether the post surface was silanized, whether the adhesive was light-irradiated, and whether Calibra luting agent was used. The micro-tensile bond strength and bonded interface of specimens in each group were evaluated. Specimens luted with Calibra or FluoroCore 2 resin-based luting agent systems were superior to those treated with Multilink or Variolink II, in terms of both bond strength and interfacial integrity. Application of silane, light-irradiation of the adhesive, or light-irradiation of the Calibra resin-based luting agent did not significantly increase the bond strength further. It can be concluded that Calibra or FluoroCore 2 resin-based luting agent systems are more suitable for luting prefabricated Easy Post in a clinical situation, while pre-silanization of the post surface and light-irradiation of XP Bond/SCA adhesive or resin-based luting agent may not be as important as hitherto considered.     

Effect of a functional monomer (MDP) on the enamel bond durability of single‐step self‐etch adhesives

The present study aimed to determine the effect of the functional monomer, 10‐methacryloxydecyl dihydrogen phosphate (MDP), on the enamel bond durability of single‐step self‐etch adhesives through integrating fatigue testing and long‐term water storage. An MDP‐containing self‐etch adhesive, Clearfil Bond SE ONE (SE), and an experimental adhesive, MDP‐free (MF), which comprised the same ingredients as SE apart from MDP, were used. Shear bond strength (SBS) and shear fatigue strength (SFS) were measured with or without phosphoric acid pre‐etching. The specimens were stored in distilled water for 24 h, 6 months, or 1 yr. Although similar SBS and SFS values were obtained for SE with pre‐etching and for MF after 24 h of storage in distilled water, SE with pre‐etching showed higher SBS and SFS values than MF after storage in water for 6 months or 1 yr. Regardless of the pre‐etching procedure, SE showed higher SBS and SFS values after 6 months of storage in distilled water than after 24 h or 1 yr. To conclude, MDP might play an important role in enhancing not only bond strength but also bond durability with respect to repeated subcritical loading after long‐term water storage.     

Shear Bond Strengths of Resin Adhesive Cements to Dentin and Ni-Cr-Be Alloy

Two adhesives, Super Bond and Panavia, were evaluated for shear bond strength to dentin. Twenty human teeth were used for each adhesive. Bonding sites were prepared in dentin (600 grit) and the adhesives applied according to the manufacturers'instructions. Bond strengths were determined with an Instron testing machine at 24 hours. Super Bond developed the strongest bond of 21.59 ± 3.91 MPa. Panavia produced a lower bond strength of 2.68 ± 1.45 MPa. Statistically, Super Bond was found to have a stronger bond than Panavia. The same two adhesives were applied to Ni-Cr-Be specimens and compared to Comspan. Twenty Rexillium III specimens were used for each adhesive at 24 hours and 20 for thermocycling. The metal specimens were ground flat (600 grit) and then air abraded with 50-micron aluminous oxide. The adhesives were applied to the metal surface in accordance with the manufacturers'instructions. One group was tested at 24 hours while the second group was tested after thermocycling (2,500 cycles at 6°C to 60°C). At 24 hours, Super Bond had a significantly stronger bond than the other materials. Comparison of the 24-hour to thermocycled bond strengths found Comspan had a significant increase in bond strength, Panavia had no significant change and Super Bond had a significant decrease in bond strength. After 2,500 thermocycles, Comspan, Panavia, and Super Bond were not significantly different in bond strength.     

In vitro study of endodontic post cementation protocols that use resin cements

STATEMENT OF PROBLEM: Sodium hypochlorite (NaOCl) may alter resin bond strength by deproteination of demineralized dentin collagen. PURPOSE: To analyze the effect of NaOCl treatment on bond adhesion and tensile strength of different post cementation protocols in vitro. MATERIAL AND METHODS: The periconductual dentin of 120 single-rooted, caries-free, unrestored human teeth was etched with 37% orthophosphoric acid. The teeth in Group I (60) were left untreated, and the teeth in Group II (60) were treated with 10% NaOCl. Four post-cementation protocols were examined (15 teeth in each) for Groups I and II: ED Primer dentin adhesive + Panavia 21 Ex; ED Primer dentin adhesive + Dual Cement; Panavia 21 Ex; and Dual Cement. For each condition, resin tags, hybrid layers over the periconductual dentin and post surface, were analyzed by scanning electron microscopy (SEM). Specimens were loaded with a uniaxial tensile force using an electromechanical testing machine until cement failure. Bond adhesion and tensile strength with different protocols were examined statistically using multiple analysis of variance at a significance level of alpha<.05. RESULTS: SEM revealed morphologic differences; Group II exhibited cylindrical, solid tags and Group I, tapered, hollow tags. Uniaxial tensile strength tests showed that in Group I, Panavia 21 Ex cement was strongest, whereas in Group II, this protocol was the weakest and Dual Cement with adhesive was the strongest. In Group II, Panavia 21 Ex diminished the tensile bond strength; however, combination with dentin adhesive increased it. CONCLUSION: Within the limitations of this study, NaOCl treatment did not significantly alter tensile bond strength, but when combined with the dentin adhesive ED Primer, a significant rise in strength resulted. A positive relationship existed between increased tag numbers and higher tensile bond strength.     

Effect of the adhesive application mode and fiber post translucency on the push-out bond strength to dentin

This study evaluated the effect of the adhesive application mode and fiber post translucency on the push-out bond strength to dentin. Bovine roots were endodontically treated, and 10 roots were used for each adhesive application mode: PB (Prime&Bond 2.1), PB + SC (Self-cure activator), PB + SBM (Scotchbond Multi-purpose adhesive system), BB (Brush&Bond), BB + CAT (chemical catalyst), and BB + SBM. The translucent Light-Post and Aestheti-Post were cemented. The roots/cemented posts were transversally sectioned to originate three thirds (cervical, middle, and apical). The push-out test was performed, and the failure mode of fractured specimens was analyzed. There was no difference between the fiber posts. For PB and BB, the use of hydrophobic adhesive resin SBM increased post bond strength. The use of SC and CAT catalyst did not affect the push-out bond strength values. The apical third presented the lowest bond strengths.