Effect of provisional cements on the bond strength of various adhesive bonding systems on dentine

Immediate Dentin Sealing for Adhesive Cementation of Indirect Restorations: A Systematic Review and Meta-Analysis

Immediate dentin sealing (IDS) involves applying an adhesive system to dentin directly after tooth preparation, before impression. This was considered an alternate to delayed dentin sealing (DDS), a technique in which hybridization is performed following the provisional phase and just before the indirect restoration luting procedure. This study aimed to compare the bond strength of restorations to dentin of the IDS and the DDS techniques throughout a systematic review and meta-analysis. The following PICOS framework was used: population, indirect restorations; intervention, IDS; control, DDS; outcomes, bond strength; and study design, in vitro studies. PubMed (MedLine), The Cochrane Library, ISI Web of Science, Scielo, Scopus, and Embase were screened up to January 2022 by two reviewers (L.H. and R.B.). In vitro papers studying the bond strength to human dentin of the IDS technique compared to the DDS technique were considered. Meta-analyses were carried out by using a software program (Review Manager v5.4.1; The Cochrane Collaboration). Comparisons were made by considering the adhesive used for bonding (two-step etch-and-rinse, three step etch-and-rinse, one-step self-etch, two-step self-etch, and universal adhesives). A total of 3717 papers were retrieved in all databases. After full-text assessment, 22 potentially eligible studies were examined for qualitative analysis, leaving a total of 21 articles for the meta-analysis. For the immediate bond strength, regardless of the adhesive strategy used, the IDS technique improved the bond strength of restorations to the dentin (p < 0.001). Taking into account the subgroup analysis, it seems that the use of the IDS technique with a two-step etch-and-rinse or a one-step self-etch adhesive system does not represent any advantage over the DDS technique (p = 0.07, p = 0.15). On the other hand, for the aged bond strength, regardless of the adhesive strategy used, the IDS technique improved the bond strength of restorations to the dentin (p = 0.001). The subgroups analysis shows that this improvement is observed only when a three-step etch-and-rinse adhesive system (p < 0.001) or when a combination of an adhesive system plus a layer of flowable resin (p = 0.01) is used. The in vitro evidence suggests that the use of the IDS technique improves the bond strength of dentin to resin-based restorations regardless of the adhesive strategy used. The use of a three-step etch-and-rinse adhesive system or the combination of an adhesive system plus a layer of flowable resin seems to considerably enhance the bond strength in the long term.

Effect of calcium silicate-based endodontic sealer on the retention of fiber posts cemented at different time intervals

Objective

To evaluate the effect of BC HiFlow, a new calcium silicate-based endodontic sealer, compared with a resin epoxy-based sealer after 2 different times of cementation on the pull-out bond strength of glass-fiber–reinforced composite posts cemented with a self-adhesive resin cement (RelyX Unicem).

Methodology

Sixty human maxillary central incisors were decoronated, prepared and obturated with gutta-percha and sealer. Roots were distributed into 5 groups according to the sealer and time of post cementation: (1) AH Plus sealer with immediate post fixation, (2) BC HiFlow with immediate post fixation, (3) AH Plus and post fixation after 7 days, (4) BC HiFlow and post fixation after 7 days, and (5) fiber post fixation in canals obturated with gutta-percha only (no sealer). After 1 week of post cementation, the pull-out test was performed and the failure mode was examined under a digital microscope. Data were analyzed using ANOVA followed by Tukey's post hoc and t tests (p < .05).

Results

With immediate post cementation, AH Plus group showed significantly higher pull-out retentive strength than the BC HiFlow and control groups (p = .009 and p < .001, respectively). There was no significant difference between the groups when the posts were cemented 7 days after obturation (p = .726). The time of post cementation had a significant influence on the canals obturated with AH Plus (p = .003). The time did not significantly affect the canals obturated with BC HiFlow (p = .289). The prominent type of failure was mixed mode in all groups.

Conclusion

BC HiFlow sealer did not affect the pull-out bond strength of glass-fiber–reinforced composite posts cemented with a self-adhesive resin cement immediately after or 7 days after obturation. For immediate post cementation, AH Plus increased the pull-out bond in comparison to BC HiFlow.

Impact of Immediate Dentin Sealing Using Universal Adhesive under Simulated Pulp Pressure on Microtensile Bond Strength of Indirect Resin Composite Restorations and Dentin Permeability

Objective  The aim of this study was to investigate the effect of immediate dentin sealing (IDS) technique using universal adhesive under simulated pulp pressure on microtensile bond strength (μTBS) of indirect resin composite restorations and dentin permeability.

Materials and Methods  Fifty extracted caries-free human third molars were used for specimens' preparation. Each molar's occlusal table was abraded flat and their roots were separated under continuous water cooling. Forty specimens were used for microtensile bond strength test (μTBST) evaluation. The μTBST specimens were randomly assigned to two groups according to the dentin sealing time; Immediate dentin sealing (IDS) and delayed dentin sealing (DDS). Each group was further subdivided into two subgroups according to the adhesive system used for dentin sealing: iBOND self-etch adhesive and GLUMA Bond Universal. All specimens were exposed to simulated pulp pressure for 1 week then restored using computer-aided design/computer-aided manufacturing (CAD/CAM) resin composite blocks. The μTBS was evaluated for all tested subgroups after 24 hours and 6 months of water storage. The remaining 10 teeth were used for the preparation of dentin discs for dentin permeability evaluation. They were divided into two groups according to type of self-etch adhesive used. Fluid filtration rate was evaluated after etching, with smear layer and after adhesive application. Results obtained were statistically analyzed using Shapiro–Wilk test and Weibull analysis.

Results  Statistically significant difference was recorded between µTBS mean values of both IDS and DDS techniques at 24 hours and after 6 months of water storage. GLUMA Bond Universal adhesive had significantly higher bond strength compared with iBond at both IDS and DDS techniques, but both adhesives showed a significant reduction in the Weibull characteristic strength after 6 months of water storage. Significant reduction in dentin permeability was recorded by both adhesives without any significant difference between them.

Conclusions  The IDS technique using universal adhesive in self-etch mode is an effective strategy for improving the final bond strength of CAD/CAM resin composite restorations and reducing dentin permeability.

Predictable bonding of adhesive indirect restorations: factors for success

Adhesive indirect restorations are a popular restorative treatment option. This article discusses the many factors that contribute to their successful adhesive cementation, including a review of how to surface treat and manage contaminants across the wide range of indirect materials available.

Critiques the current various adhesive strategies used by resin cements at the tooth tissue interface.

Describes how to prepare the fitting surface of a wide range of restorative materials for adhesive cementation.

Discusses how to mitigate against contaminants during the adhesive cementation process.

Substantial in-vitro and emerging clinical evidence supporting immediate dentin sealing

The application of resin adhesive to freshly cut dentin after teeth preparation, the so-called immediate dentin sealing (IDS) has been suggested as an alternative to the delayed dentin sealing (DDS), a technique in which resin adhesive is applied just before final bonding of indirect restorations.

The aim of this review is to demonstrate the evidence of the claimed advantages made by the proponents of IDS technique.

The results of this review revealed substantial in-vitro evidence supporting the IDS benefits including improved bond strength, reduced dentin permeability, improved restorations’ adaptation, and increased fracture strength of the restorations. Clinical studies have shown that IDS improves survival of ceramic laminate veneers bonded to prepared teeth with increased exposure of dentin. Moreover, it has been shown that IDS reduces post-cementation hypersensitivity in full coverage restorations, which is characterized by exposure of a large number of dentinal tubules. The selection of filled resin adhesive that is capable of producing thick adhesive layer appears to contribute to the success of the technique. Furthermore, careful management of the oxygen inhibition layer before conventional impression making and proper cleaning of the residual temporary cement used with provisional restorations appears to affect the outcome of the restorations.

Immediate Dentin Sealing: A Literature Review

Purpose

The immediate application of a dentin-bonding agent after tooth preparation and before impression-taking (immediate dentin sealing [IDS]) has been suggested to provide several advantages concerning bacterial microleakage, hypersensitivity, and bonding quality. We reviewed the literature and clarified certain aspects related to each step of IDS application.

Materials and Methods

The search strategy comprised an electronic research in MEDLINE, Cochrane, Ovid and Scopus for studies published from January 1990 to December 2020 regarding the IDS technique and including both in vitro and clinical studies.

Results

After exclusion of irrelevant or duplicate articles, 88 articles focusing on aspects of the IDS technique were assessed. IDS seems to be advantageous with regard to bond strength, gap formation, bacterial microleakage, and dentin hypersensitivity. However, issues arising from interaction with impression materials, the provisional phase, and conditioning methods before cementation require further investigation.

Conclusion

There are no documented reasons preventing clinicians applying IDS in their everyday practice. On the contrary, the presented technique seems to be beneficial in certain aspects regarding indirect restorations.

The effect of temporary sealing materials and cleaning protocols on the bond strength of resin cement applied to dentin using the resin-coating technique

This study evaluated the effect of temporary sealing materials and cleaning protocols on the bond strength of resin cement applied to dentin using resin-coating technique. Scotchbond Universal Adhesive and Filtek Supreme Ultra Flowable were applied to bovine dentin. Forty-five specimens were divided into the following three groups according to the temporary sealing materials: Cav-: CAVITON EX, Vas-: COCOA BUTTER and FIT SEAL, and Sep-: Washable SEP and FIT SEAL. Each material was placed on resin-coated dentin. After 1-week water storage, one of the following three cleaning protocols was performed: -WA: washed with water, -BR: brushed with PRESSAGE, and -AF: cleaned with AIR-FLOW. Microtensile bond strength test and EDS analysis were conducted. Irrespective of the cleaning protocol used, Washable SEP demonstrated less residual debris on resin-coated dentin, resulting in high bond strength. Regardless of the temporary sealing material applied, AIR-FLOW demonstrated less residual debris, resulting in high bond strength.

Effect of immediate dentine sealing on the aging and fracture strength of lithium disilicate inlays and overlays

OBJECTIVES

The objectives of this study were to compare the in vitro, laboratory aging, fracture strength, failure mode and reparability of molars restored with lithium disilicate inlays and overlays in conjunction with or without immediate dentin sealing (IDS).

METHODS

Forty extracted, sound human molars were selected and divided into four groups: 1) Inlays with IDS; 2) Inlays without IDS; 3) Overlays with IDS; 4) Overlays without IDS. Standard MOD preparations were made (3 mm wide, 5 mm deep) and in groups 2 and 4, all the cusps were reduced by 2 mm. Directly following tooth preparation, IDS was applied in specimens belonging to groups 1 and 3. The indirect restorations were luted with a heated composite. The restored teeth were subsequently challenged during aging (1.2 million cycles) and thermocycling loading (8000 cycles, 5-55 degrees C). Subsequently, the fracture strength was tested by a load to failure test at 45°. A failure analysis was performed using light- and scanning electron microscopy. The results were analyzed using two-way ANOVA and a Fisher exact test.

RESULTS

Mean fracture load + SD (N) were: Group 1 (n = 12): 1610 ± 419; Group 2 (n = 12): 1115 ± 487; Group 3 (n = 12): 2011 ± 496; Group 4 (n = 12): 1837 ± 406. Teeth restored with an onlay were stronger than those restored with an inlay restoration (p < .001). Teeth with IDS were stronger overall than those without IDS (p = .026). The interaction between preparation type and the mode of dentin conditioning had no statistically significant influence on fracture strength (p = .272). Subsequently, custom hypothesis tests showed that there was no statistically significant difference in fracture strength between inlays with IDS and overlays without IDS (p = .27). Overlays tend to fail in a more destructive, non-reparable way (p = .003).

SIGNIFICANCE

Both variables IDS and overlay preparation improve overall fracture strength. Inlays with IDS and overlays without IDS didn't differ in fracture strength. Both inlays and overlays are strong enough to withstand physiological chewing forces.

Influência do selamento dentinário imediato com sistema adesivo universal na resistência de união

Resumo Introdução O selamento dentinário imediato consiste na aplicação imediata de um sistema adesivo sobre exposições dentinárias após o preparo dental e previamente aos procedimentos de moldagem. Objetivo O objetivo do estudo foi avaliar a influência do selamento dentinário imediato (SDI) na resistência adesiva do sistema adesivo universal (Single Bond Universal, 3M ESPE) em dentina, na forma de aplicação autocondicionante. Material e método 30 incisivos bovinos foram divididos em 3 grupos (n = 10): grupo S (Sem Selamento Dentinário Imediato), grupo SDI (Selamento Dentinário Imediato) e grupo SDIF (Selamento Dentinário Imediato + Resina Flow). A superfície vestibular foi desgastada com pontas diamantadas até a exposição superficial de dentina. A simulação da lama dentinária foi realizada com lixa d’água por 30s e a dentina tratada de acordo com o respectivo grupo. Para simulação da restauração provisória, foram cimentados blocos de resina bisacrílica com cimento de óxido de zinco. Após 7 dias, foi realizada a cimentação definitiva de blocos de resina com cimento resinoso dual (RelyX ARC, 3M ESPE). Os espécimes foram seccionados para obtenção de filetes de 1mm2 e submetidos ao teste de microtração, em uma máquina universal de ensaios (Instron). Os resultados foram tabulados e submetidos a Análise de Variância (ANOVA) e teste de Tukey a 5% de significância. Resultado Observaram-se maiores valores de resistência de união para o grupo SDIF (23,53 MPa), diferindo estatisticamente do Grupo S (17,65 MPa) (p=0,008). O grupo SDI apresentou valor médio de resistência de união (19,25 MPa), não diferindo estatisticamente dos grupos S (p=0,68) e SDIF (p=0,07). Conclusão Recomenda-se a técnica de selamento dentinário imediato seguido da uma camada de resina flow, em exposições dentinárias ocasionadas pelo preparo dental para restaurações indiretas.

Comparison between shear forces applied on the overlay-dental tissue interface using different bonding techniques: An in vitro study

Aim:

The aim of this study was to compare the adhesion of glass-ceramic overlays to tooth structure, under the effect of shear forces, using different bonding systems.

Materials and Methods:

Thirty healthy lower third molars were selected and randomly allocated into three groups (n = 10). Group 1: overlays bonded to tooth structure using Panavia V5 with immediate dentin sealing (IDS); Group 2: overlays bonded using Panavia V5 without IDS; and Group 3: overlays bonded using heated composite combined with a bonding agent with IDS. All the restorations were made of glass-ceramic (Suprinity, Vita). The restored teeth were then stored in distilled water for 7 days and at room temperature. Shear forces were applied using a universal testing machine. Load and displacement were recorded at intervals of 0.1 s. A statistical analysis was used to compare the groups.

Results:

The mean resistance to fractures ± standard deviation obtained for the Groups 1, 2, and 3 was, respectively, 15.7440 ± 2.13, 12.0750 ± 1.41, and 8.33364 ± 2.85 MPa. The analysis of variance was highly significant (P < 0.001) allowing us to reject the null hypothesis of equality between the three groups. Comparisons between pairs also provided significant results.

Conclusion:

Bonding using Panavia V5 with IDS showed a better resistance to shear forces when compared to other bonding techniques. The application of IDS increased the adhesion.

Immediate dentin sealing for indirect bonded restorations

PURPOSE

The aim of this article is to review available literature on the clinical procedure of immediate dentine sealing for indirect bonded restorations.

STUDY SELECTION

More than 40 articles reporting the technique, studies, outcomes, etc. were reviewed after PUBMED/MEDLINE search, most of them addressing the specific situation of dentin bonding for indirect restorations.

RESULTS

It is known that tooth preparation for indirect bonded restorations can result in significant dentin exposures. Immediate application and polymerization of the dentin bonding agent to the freshly cut dentin, prior to impression making is therefore recommended by some authors. Literature indicates that this procedure, immediate dentine sealing (IDS), appears to achieve improved bond strength, fewer gap formations, decreased bacterial leakage, and reduces post-cementation sensitivity. This rational approach to adhesion is also reported to have a positive influence on tooth structure preservation, patient comfort, and long term survival of indirect bonded restorations.

CONCLUSION

In the extensive literature regarding advantages of using IDS technique significant differences have been shown when compared to Delayed Dentine Sealing. Although more research is required in this field, presently there are NO scientific reasons not to recommend IDS in routine practice.

Cytotoxicity of temporary cements on bovine dental pulp-derived cells (bDPCs) using realtime cell analysis

PURPOSE

To evaluate the cytotoxicity of temporary luting cements on bovine dental pulp-derived cells (bDPCs).

MATERIALS AND METHODS

Four different temporary cements were tested: Rely X Temp E (3M ESPE), Ultratemp (Ultradent), GC Fuji Temp (GC), and Rely X Temp NE (3M ESPE). The materials were prepared as discs and incubated in Dulbecco's modified eagle's culture medium (DMEM) for 72 hours according to ISO 10993-5. A real-time cell analyzer was used to determine cell vitality. After seeding 200 µL of the cell suspensions into the wells of a 96-well plate, the bDPCs were cured with bioactive components released by the test materials and observed every 15 minutes for 98 hours. One-way ANOVA and Tukey-Kramer tests were used to analyze the results of the proliferation experiments.

RESULTS

All tested temporary cements showed significant decreases in the bDPCs index. Rely X Temp E, GC Fuji Temp, and Rely X Temp NE were severely toxic at both time points (24 and 72 hours) (P<.001). When the cells were exposed to media by Ultratemp, the cell viability was similar to that of the control at 24 hours (P>.05); however, the cell viability was significantly reduced at 72 hours (P<.001). Light and scanning electron microscopy examination confirmed these results.

CONCLUSION

The cytotoxic effects of temporary cements on pulpal tissue should be evaluated when choosing cement for luting provisional restorations.

Effect of different surface-cleaning techniques on the bond strength of composite resin restorations

STATEMENT OF PROBLEM

Different techniques have been suggested for cleaning dentin surfaces after the removal of an interim prosthesis and before the application of a bonding agent. How different surface-cleaning techniques affect the bond strength of the composite resin restorations is not clear.

PURPOSE

The purpose of this study was to investigate the effects of different surface-cleaning techniques on the bond strength of composite resin restorations and the surface topography of the prepared tooth surfaces.

MATERIAL AND METHODS

The occlusal surfaces of 25 molars were ground until the dentin was exposed. A bonding agent and interim cement were applied on the teeth. The teeth were divided into 5 groups (n=5) according to the method used for surface-cleaning (microairborne-particle abrasion, alcohol, rubber-rotary instrument, desiccating agent, and control). Once the surfaces of the teeth had been cleaned, the same bonding material was applied to the teeth. A 5-mm-thick composite resin layer was built up. Each specimen was sectioned to microbars, and 6 centrally located beams were selected for microtensile testing (n=30) (1.10 ±0.10 mm). The data were statistically analyzed with 1-way ANOVA (1-sample Kolmogorov-Smirnov test). The Bonferroni test was used for significantly different groups (α=.05). One specimen from each group was observed under a scanning electron microscope and an atomic force microscope. Energy dispersive x-ray analysis also was performed.

RESULTS

Bond strength values were in the following descending order: microairborne-particle abrasion, desiccating agent, alcohol, rubber-rotary instrument, control. Differences between the microairborne-particle abrasion group and the remainder of the groups, desiccating agent--rubber-rotary instrument, desiccating agent-control, alcohol--rubber-rotary instrument, and alcohol-control groups, were statistically significant (P<.05). The microairborne-particle abrasion group displayed the roughest surface and a different surface topography from the remainder of the groups. Increased aluminum was observed in the microairborne-particle abrasion group.

CONCLUSIONS

Surface-cleaning techniques, except for the rubber-rotary instrument, increased the bond strength of composite resin. The roughest dentin surfaces and highest bond strength were achieved with the microairborne-particle abrasion technique.

An in vitro evaluation of effect of eugenol exposure time on the shear bond strength of two-step and one-step self-etching adhesives to dentin

Objectives:

To evaluate the effect of the eugenol exposure time of an eugenol-based provisional restorative material on the shear bond strength of two-step and one-step self-etching adhesives to dentin, at three different time intervals of 24 h, 7 days, and 14 days.

Materials and Methods:

Forty extracted human posterior teeth were sectioned mesiodistally to obtain two halves and the resulting 80 halves were randomly assigned into four groups of 20 specimens each (Group-I, -II, -III, and -IV). Cavities of specified dimensions were prepared to expose dentin surface. In Group-I, temporarization was carried out with noneugenol cement (Orafil-G) for 24 h (control group). In Group-II, -III, and -IV, temporarization was carried out with eugenol cement (intermediate restorative material (IRM)) for 24 h, 7 days, and 14 days, respectively. Each group was further divided into two subgroups of 10 teeth each for two-step (Adper SE Plus) and one-step (Adper Easy One) self-etch adhesive systems, respectively. A plastic tube loaded with microhybrid composite resin (Filtek Z-350, 3M) was placed over the dentin surface and light cured. The specimens were subjected to shear stress in universal testing machine.

Results:

Group-II yielded low shear bond strength values compared with Group-III, -IV, and Group-I, which was statistically significant.

Conclusions:

The prior use of eugenol containing temporary restorative material reduced the bond strength of self-etch adhesive systems at 24-h period. No reduction in bond strength at 7 or 14 days exposure was observed with either two-step or one-step self-etch adhesive.

Thickness of immediate dentin sealing materials and its effect on the fracture load of a reinforced all-ceramic crown

Objectives:

The objective of this study is to evaluate, in vitro, the thickness of immediate dentin sealing (IDS) materials on full crown preparations and its effect on the fracture load of a reinforced all-ceramic crown.

Materials and Methods:

Sixty premolars received full crown preparation and were divided into the following groups according to the IDS technique: G1-control; G2-Clearfil SE Bond; and G3-Clearfil SE Bond and Protect Liner F. After the impressions were taken, the preparations were temporized with acrylic resin crowns. IPS empress 2 restorations were fabricated and later cemented on the preparations with Panavia F. 10 specimens from each group were submitted to fracture load testing. The other 10 specimens were sectioned buccolingually before the thicknesses of Panavia F, Clearfil SE Bond and Protect Liner F were measured in 10 different positions using a microscope.

Results:

According to analysis of variance and Tukey's test, the fracture load of Group 3 (1300 N) was significantly higher than that of Group 1 (1001 N) (P < 0.01). Group 2 (1189 N) was not significantly different from Groups 1 and 3. The higher thickness of Clearfil SE Bond was obtained in the concave part of the preparation. Protect Liner F presented a more uniform range of values at different positions. The thickness of Panavia F was higher in the occlusal portion of the preparation.

Conclusions:

The film thickness formed by the IDS materials is influenced by the position under the crown, suggesting its potential to increase the fracture load of the IPS empress 2 ceramic crowns.

Cytotoxicity testing of temporary luting cements with two- and three-dimensional cultures of bovine dental pulp-derived cells

This study evaluated the cytotoxicity of eugenol-containing and eugenol-free temporary luting cements. For cytotoxicity testing, bovine pulp-derived cells transfected with Simian virus 40 Large T antigen were exposed to extracts of eugenol-containing (Rely X Temp E) and eugenol-free (Provicol, PreVISION CEM, and Rely X Temp NE) temporary luting cements for 24 h. The cytotoxicity of the same materials was also evaluated in a dentin barrier test device using three-dimensional cell cultures of bovine pulp-derived cells. The results of the cytotoxicity studies with two-dimensional cultures of bovine dental pulp-derived cells revealed that cell survival with the extracts of Rely X Temp E, Provicol, PreVISION CEM, and Rely X Temp NE was 89.1%, 84.9%, 92.3%, and 66.8%, respectively. Rely X Temp NE and Provicol showed cytotoxic effects on bovine dental pulp-derived cells (P < 0.05). The results of the dentin barrier test revealed that cell survival with the above-mentioned temporary cement was 101.5%, 91.9%, 93.5%, and 90.6%, respectively. None of the temporary luting cements significantly reduced cell survival compared with the negative control in the dentin barrier test (P > 0.05). Biologically active materials released from temporary luting cements may not influence the dentine-pulp complex if the residual dentine layer is at least 0.5 mm thick.

Influence of Endodontic Sealer Composition and Time of Fiber Post Cementation on Sealer Adhesiveness to Bovine Root Dentin

This study aimed to assess the influence of the type of endodontic sealer (salicylate resin-based sealer vs. two endodontic sealers) and the time of fiber post cementation after root filling on the post adhesion to bovine root dentin. Sixty bovine roots were assigned to six groups (n=10), considering an experimental design with two factors (factorial 3x2): endodontic sealer factor in three levels [epoxy resin-based sealer (AH Plus), eugenol-based sealer (Endofill), and salicylate resin-based sealer plus mineral trioxide aggregate - MTA (MTA Fillapex)] and time for post cementation factor in two levels (immediate post cementation or 15 days after root canal filling). After post cementation, 2-mm-thick slices were produced and submitted to push-out test. The failure modes were analyzed under a 40× stereomicroscope and scored as: adhesive at cement/dentin interface; adhesive at cement/post interface; cement cohesive; post cohesive; dentin cohesive; or mixed. Data were analyzed using two-way ANOVA and Tukey's post-hoc tests (α=0.05). When the fiber posts were cemented immediately after the root canal filling, the bond strengths were similar, independent of the endodontic sealer type. However, after 15 days, the epoxy resin-based sealer presented higher bond strength than the other sealers (p<0.05). Comparison between each sealer in different experimental times did not reveal any differences. The main failure type was adhesive at dentin/cement interface (89.4%). The time elapsed between the root canal filling and post cementation has no influence on post/root dentin adhesion. On the contrary, the type of endodontic sealer can influence the adhesion between fiber posts and root dentin.

Influence of immediate dentin sealing techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays

SUMMARY This research evaluated the influence of immediate dentin sealing (IDS) techniques on cuspal deflection and fracture resistance of teeth restored with composite resin inlays. Forty-eight maxillary premolars were divided into four groups: G1, sound teeth (control); G2, without IDS; G3, IDS with Clearfil SE Bond (CSE); and G4, IDS with CSE and Protect Liner F. The teeth from groups 2, 3, and 4 received mesio-distal-occlusal preparations. The impressions were made with vinyl polysiloxane, followed by provisional restoration and storage in water for seven days. The impressions were poured using type IV die stone, and inlays with Filtek Z250 composite resin were built over each cast. The inlays were luted with Panavia F. After storage in water for 72 hours, a 200-N load was applied on the occlusal surface using a metal sphere connected to a universal testing machine, and the cuspal deflection was measured with a micrometer. The specimens were then submitted to an axial load until failure. The following mean cuspal deflection (μm) and mean fracture resistance (N) followed by the same lowercase letter represent no statistical difference by analysis of variance and Tukey (p<0.05): cuspal deflection: G1, 3.1 ± 1.5(a); G2, 10.3 ± 4.6(b); G3, 5.5 ± 1.8(ac); and G4, 7.7 ± 5.1(bc); fracture resistance: G1, 1974 ± 708(a); G2, 1162 ± 474(b); G3, 700 ± 280(b); and G4, 810 ± 343(b). IDS with CSE allowed cuspal deflection comparable with that associated with sound teeth. The application of Protect Liner F did not contribute to a decrease in cuspal deflection. The IDS techniques did not influence the fracture resistance of teeth.

The effect of eugenol-free temporary cement's remnants on retention of full metal crowns: comparative study

INTRODUCTION

The aim of this study was to evaluate the effects of eugenol-free temporary cement's remnants on the retentive strength of full metal crowns luted via zinc phosphate and resin cement (Maxcem) to the tooth structure.

MATERIALS AND METHODS

Forty complete standardized Ni-Cr crowns in four groups were cemented by two types of permanent cements: zinc phosphate cement and resin cement (Maxcem). In the two groups before permanent cementation of crowns, temporary acrylic crowns were cemented by eugenol-free temporary cement. Crowns' retention was evaluated by Universal testing machine. All data were analyzed by means of one-way ANOVA test in SPSS software version 11.5 (α=0.05).

RESULTS

There was no significant difference in groups with prior using eugenol-free temporary cement and groups with just using two permanents cement (p-value≥0.05).

DISCUSSION

The application of temporary cement before permanent cementation of full metal crowns does not have any adverse effect on retention of full metal crowns, when temporary cements are removed properly.

The effects of desensitizing resin, resin sealing, and provisional cement on the bond strength of dentin luted with self-adhesive and conventional resincements

STATEMENT OF PROBLEM

Self-adhesive resin cements were designed to bond without any pretreatment of dentin. However, pretreatments such as the application of desensitizing resin or the resin sealing of dentin with priming/bonding solutions might influence the bonding quality of these self-adhesive resin cements. Little is known about the effect of dentin pretreatment on the bond quality of self-adhesive resin cements.

PURPOSE

This study evaluated whether dentin desensitizing or sealing methods influenced the shear bond strength of 1 self-adhesive and 2 conventional resin cements.

MATERIAL AND METHODS

One-hundred and eighty human molars were assigned to 5 different pretreatment groups: 1) freshly ground dentin, 2) glutaraldehyde/hydroxyethylmethacrylate (HEMA) desensitized dentin (Gluma), 3) contamination of desensitized dentin with provisional cement, 4) sealed dentin (dual bonding technique), and 5) contamination of sealed dentin with provisional cement. The shear bond strength of a self-adhesive resin cement (RelyX Unicem; RXU) and 2 conventional resin cements (Variolink II; VAR, Panavia 21; PAN) was assessed for each pretreatment group (n=12 per cement types). Two-way ANOVA and 1-way ANOVA together with the post hoc Tukey multiple comparison (α=.05) were performed.

RESULTS

On freshly ground dentin, PAN exhibited the highest shear bond strength values (P<.001). The use of the glutaraldehyde/HEMA resulted in a significant increase in the bond strength of RXU as compared to fresh dentin (P<.001). Resin sealing of dentin increased the bond strength of RXU but had no significant effect on VAR or PAN. RXU exhibited the highest mean bond strength after the contamination of resin-sealed dentin by provisional cement.

CONCLUSIONS

Glutaraldehyde/HEMA treatment and resin sealing of dentin have a beneficial effect on the shear bond strength of self-adhesive resin cement (RXU). Contamination of dentin with provisional cement has no influence on the bond strength of the self-adhesive resin cement (RXU) or VAR but lowered the bond strength of PAN.

Influence of immediate dentin sealing on the shear bond strength of pressed ceramic luted to dentin with self-etch resin cement

Objectives. To examine the effect of immediate dentin sealing (IDS), with dentin bonding agents (DBAs) applied to freshly cut dentin, on the shear bond strength of etched pressed ceramic luted to dentin with RelyX Unicem (RXU) cement. Method. Eighty extracted noncarious third molars were ground flat to expose the occlusal dentin surfaces. The teeth were randomly allocated to five groups (A to E) of sixteen teeth each. Groups A to D were allocated a dentin bonding agent (Optibond FL, One Coat Bond, Single Bond, or Go!) that was applied to the dentin surface to mimic the clinical procedure of IDS. These specimen groups then had etched glass ceramic discs (Authentic) luted to the sealed dentin surface using RXU. Group E (control) had etched glass ceramic discs luted to the dentin surface (without a dentin bonding agent) using RXU following the manufacturer's instructions. All specimens were stored for one week in distilled water at room temperature and then shear stressed at a constant cross-head speed of 1 mm per minute until failure. Statistical analysis was performed by ANOVA followed by post hoc Tukey HSD method (P < 0.05) applied for multiple paired comparisons. Results. The shear bond strength results for group A to E ranged from 6.94 ± 1.53 to 10.03 ± 3.50 MPa. One-way ANOVA demonstrated a difference (P < 0.05) between the groups tested and the Tukey HSD demonstrated a significant (P < 0.05) difference between the shear bond strength (SBS) of Optibond FL (Group A) and Go! (Group D). There was no statistical difference (P > 0.05) in the SBS between the test groups (A-D) or the control (group E). Conclusion. IDS using the dentin bonding agents tested does not statistically (P > 0.05) affect the shear bond strength of etched pressed ceramic luted to dentin with RXU when compared to the control.

Bond strength of a composite resin to an adhesive luting cement

This study evaluated the influence of surface treatment on the shear bond strength of a composite resin (CR), previously submitted to the application of a temporary cement (TC), to an adhesive luting cement. Eight-four CR cylinders (5 mm diameter and 3 mm high) were fabricated and embedded in acrylic resin. The sets were divided into 6 groups (G1 to G6) (n=12). Groups 2 to 6 received a coat of TC. After 24 h, TC was removed and the CR surfaces received the following treatments: G2: ethanol; G3: rotary brush and pumice; G4: air-abrasion; G5: air-abrasion and adhesive system; G6: air-abrasion, acid etching and adhesive system. G1 (control) did not receive TC or any surface treatment. The sets were adapted to a matrix and received an increment of an adhesive luting cement. The specimens were subjected to the shear bond strength test. ANOVA and Tukey's tests showed that G3 (8.53 MPa) and G4 (8.63 MPa) differed significantly (p=0.001) from G1 (13.34 MPa). The highest mean shear bond strength values were found in G5 (14.78 MPa) and G6 (15.86 MPa). Air-abrasion of CR surface associated with an adhesive system provided an effective bond of the CR to the adhesive luting cement, regardless the pre-treatment with the phosphoric acid.

Effect of Eugenol Exposure Time and Post-removal Delay on the Bond Strength of a Self-etching Adhesive to Dentin

The presence of a provisional restoration containing eugenol for one week or longer does not interfere with the bond strength of self-etching adhesives to dentin. If a eugenol-based provisional restoration remained in place for only 24 hours, a delay of one week re-establishes proper bond strength.

An effect of immediate dentin sealing on the shear bond strength of resin cement to porcelain restoration

PURPOSE

The aim of this study was to determine differences in shear bond strength to human dentin using immediate dentin sealing (IDS) technique compared to delayed dentin sealing (DDS).

MATERIALS AND METHODS

Forty extracted human molars were divided into 4 groups with 10 teeth each. The control group was light-cured after application of dentin bonding agent (Excite® DSC) and cemented with Variolink® II resin cement. IDS/SE (immediate dentin sealing, Clearfil™ SE Bond) and IDS/SB (immediate dentin sealing, AdapterTM Single Bond 2) were light-cured after application of dentin bonding agent (Clearfil™ SE Bond and Adapter™ Sing Bond 2, respectively), whereas DDS specimens were not treated with any dentin bonding agent. Specimens were cemented with Variolink® II resin cement. Dentin bonding agent (Excite® DSC) was left unpolymerized until the application of porcelain restoration. Shear strength was measured using a universal testing machine at a speed of 5 mm/min and evaluated of fracture using an optical microscope.

RESULTS

The mean shear bond strengths of control group and IDS/SE group were not statistically different from another at 14.86 and 11.18 MPa. Bond strength of IDS/SE group had a significantly higher mean than DDS group (3.14 MPa) (P < .05). There were no significance in the mean shear bond strength between IDS/SB (4.11 MPa) and DDS group. Evaluation of failure patterns indicates that most failures in the control group and IDS/SE groups were mixed, whereas failures in the DDS were interfacial.

CONCLUSION

When preparing teeth for indirect ceramic restoration, IDS with Clearfil™ SE Bond results in improved shear bond strength compared with DDS.

The effect of root canal sealers and timing of cementation on the microlekage of the parapost luted with resin cement

OBJECTIVES

The objectives of the study were to study the effect of root canal sealers either eugenol or non-eugenol and timing of cementation on microleakage of the parapost luted with resin cement.

MATERIALS AND METHODS

Seventy extracted human, single-rooted teeth were instrumented using a crown-down technique. All teeth were instrumented up to a size 50 .04 taper ProFile followed by the use of Gates Glidden drills from size 2 up to 5. Following instrumentation, the teeth were randomly divided into four experimental groups of fifteen teeth each, based on type of root canal sealer (eugenol or non-eugenol sealer) and timing of post cementation (immediate or delayed). The remaining ten teeth were divided into two control groups with five teeth per group. All teeth were tested for microleakage using a fluid filtration method.

RESULTS

The microleakage of the paraposts luted with resin cement increased over time, irrespective of sealer type or timing of post cementation. Immediate post cementation following obturation with AH26 (non-eugenol sealer) produced the least microleakage at all three time periods at 24 h, 2 months and 3 months.

CONCLUSIONS

The microleakage paraposts luted with resin cement was not influenced by either sealer type or timing of post placement. All experimental groups demonstrated a significant increase in microleakage over time as well as the presence of voids at the resin-dentin interface.

The effects of tooth preparation cleansing protocols on the bond strength of self-adhesive resin luting cement to contaminated dentin

This in vitro study evaluated the bond strength of a self-adhesive luting cement after using four different techniques to remove surface contamination on dentin. Extracted human molars were flattened to expose the dentin surface and prepared for full crown preparation. Acrylic temporary crowns were fabricated and placed using temporary cement. The specimens were stored at room temperature with 100% relative humidity for seven days. Following removal of the temporary crowns, the specimens were randomly divided into four groups, and excess provisional cement was removed with (1) a hand instrument (excavator), (2) prophy with a mixture of flour pumice and water (3) aluminous oxide abrasion with a particle size of 27 microm at 40 psi and (4) aluminous oxide abrasion with a particle size of 50 microm at 40 psi. The microstructure morphology of the tooth surface was evaluated and residual materials were detected using SEM and EDS analysis of randomly selected specimens. The ceramics were treated with 9.5% hydrofluoric acid-etch and silanized to the prepared dentin prior to cementing with self-adhesive resin cement (RelyX Unicem, 3M ESPE). The shear bond strength was determined at a crosshead speed of 0.5 mm/minute. The results were analyzed with one-way ANOVA, followed by Tukey's test. Particle abrasion treatment of dentin with an aluminous oxide particle provided the highest values of bond strength, while hand instrument excavation was the lowest (p < 0.05). Aluminous oxide particle size did not significantly influence the bond strength at 40 psi. The use of low pressure and small particle abrasion treated dentin as a mechanical cleansing protocol prior to definitive cementation increased the bond strength of self-adhesive resin-luting cement to dentin following eugenol-containing temporary cement.

Immediate dentin sealing supports delayed restoration placement

STATEMENT OF PROBLEM

Immediate dentin sealing (IDS) is a new approach in indirect restorations. Dentin is sealed immediately following tooth preparation, prior to impression making. It is not known whether it is still possible to obtain an efficient bond between the resin-coated dentin and the restoration after 2 to 4 months of placement of provisional restorations.

PURPOSE

The purpose of this study was to determine if there were differences in microtensile bond strength to human dentin using the IDS technique when comparing 2, 7, and 12 weeks of delay until restoration placement, using 2 different dentin bonding agents (DBAs). Previously published preliminary IDS data were included for comparison.

MATERIAL AND METHODS

Fifty freshly extracted human molars were obtained and divided into 10 groups. A 3-step etch-and-rinse DBA (Optibond FL) and a 2-step self-etching DBA (SE Bond) were used. For each DBA, the control (C) specimens were prepared using a direct immediate bonding technique and composite restoration (Z100). Preparation of the other specimens used an indirect approach without dentin prebonding (delayed dentin sealing, DDS) or with immediate dentin sealing (IDS), immediately following preparation. IDS teeth had provisional restorations (Tempfil inlay) placed for 2 weeks (IDS-2W), 7 weeks (IDS-7W), or 12 weeks (IDS-12W) before restoration placement. All teeth were prepared for a nontrimming microtensile bond strength test (MTBS) 24 hours after definitive restoration with composite overlays (Z100). Ten to 11 beams (0.9 x 0.9 x 11 mm) from each tooth were selected for testing. MTBS data obtained from the 10 experimental groups were analyzed with a 2-way analysis of variance (ANOVA, dentin bonding system, and sequence of application) with each tooth (mean MTBS from the 10-11 beams) used as a single measurement. The Tukey HSD post hoc test was used to detect pairwise differences among experimental groups (alpha=.05). Fractured beams were also analyzed under stereoscopic microscope (x 30) and SEM.

RESULTS

For both adhesives, the mean microtensile bond strengths of C and all IDS groups were not significantly different and exceeded 45 MPa. DDS groups exhibited lower bond strength than all others sequences (P<.001) with SE Bond at 1.81 MPa significantly lower (P=.026) than Optibond FL at 11.58 MPa. The highest mean microtensile bond strength values were found with Optibond FL at 7 weeks (66.59 MPa) and 12 weeks (59.11 MPa). These were significantly higher than SE Bond in the same conditions with values of 51.96 MPa and 45.76 MPa (P=.001 and P=.003), respectively. Failures in DDS groups were all interfacial and purely adhesive. Both C and IDS-2W groups demonstrated interfacial failure that was typically mixed with both areas of failed adhesive resin and areas of cohesively failed dentin while IDS-7W and IDS-12W failed consistently between the existing resin coating (used during IDS) and the overlaying composite resin.

CONCLUSIONS

When preparing teeth for indirect bonded restorations, IDS with a 3-step etch-rinse or a 2-step self-etching DBA (prior to impression making) results in microtensile bond strength similar to that obtained with a freshly placed adhesive. The bond strength is not affected by up to 12 weeks of elapsed time prior to placement of the definitive restoration.

Influence of previous provisional cementation on the bond strength between two definitive resin-based luting and dentin bonding agents and human dentin

This study evaluated the effect of two different types of provisional luting agents (RelyX Temp E, eugenol-based; RelyX Temp NE, eugenol-free) on the shear bond strengths between human dentin and two different resin-based luting systems (RelyXARC-Single Bond and Duo Link-One Step) after cementation with two different techniques (dual bonding and conventional technique). One hundred human molars were trimmed parallel to the original long axis, to expose flat dentin surfaces, and were divided into three groups. After related surface treatments for each specimen, the resin-based luting agent was applied in a silicone cylindrical mold (3.5 x 4 mm), placed on the bonding-agent-treated dentin surfaces and polymerized. In the control group (n = 20), the specimens were further divided into two groups (n = 10), and two different resin-based luting systems were immediately applied following the manufacturer's protocols: RelyX ARC-Single Bond (Group I C) and Duo Link-One Step (Group II C). In the provisionalization group (n = 40), the specimens were further divided into four subgroups of 10 specimens each (Group I N, I E and Group II N, II E). In Groups I N and II N, eugenol-free (RelyX NE), and in groups I E and II E, eugenol-based (RelyX E) provisional luting agents (PLA), were applied on the dentin surface. The dentin surfaces were cleaned with a flour-free pumice, and the resin-based luting systems RelyX ARC (Group I N and E) and Duo Link (Group II N and E) were applied. In the Dual bonding groups (n = 40), the specimens were divided into four subgroups of 10 specimens each (Group I ND, ED and Group II ND, ED). The specimens were treated with Single Bond (Groups I ND and ED) or One Step (Groups II ND and ED). After the dentin bonding agent treatment, RelyX Temp NE was applied to Groups I ND and II ND, and RelyX Temp E was applied to Groups I ED and II ED. The dentin surfaces were then cleaned as described in the provisionalization group, and the resin-based luting systems were applied: RelyX ARC-Single Bond (Group I ND and ED) and Duo Link-One Step (Group II ND and ED). After 1,000 thermal cycles between 5 degrees C and 55 degrees C, shear bond testing was conducted at a crosshead speed of 0.5 mm/minutes. One-way ANOVA, followed by a post hoc Tukey test (alpha = 0.05) was done. The dentin-resin-based luting system interfaces were evaluated under a scanning electron microscope. There was a significant reduction in the mean shear bond strength values of groups subjected to the provisionalization compared to the control and dual bonding technique groups (p < 0.05). The composition of provisional luting did not create a significant difference with regard to reducing shear bond strength values (p > 0.05). With regard to resin based luting systems, the shear bond strength values of the double-bond technique groups were not significantly different from the controls (p > 0.05).

The effect of two root canal sealers on the retentive strength of glass fibre endodontic posts

This study was undertaken to examine the effect of eugenol-containing and non-eugenol-containing root canal sealers on the retention strength of glass fibre endodontic posts (ParaPost Fibre White) luted with a resin cement (ParaPost cement). We also examined the mode of failure that occurred visually by using scanning electron microscopy. Seventy-two single rooted, recently extracted, premolar teeth were root canal treated and randomly divided into two groups. Group 1 was obturated with gutta percha and a calcium hydroxide-based sealer (Sealapex, Kerr). Group 2 was obturated with gutta percha and a eugenol-based sealer (Tubli-Seal Kerr). The teeth were stored for 1 week in distilled water at 37 degrees C and then prepared for 9 mm posts with a 1.40-mm drill. The matching glass fibre post was luted with a resin cement following the manufacturer's instructions. The samples were stored for 1 week and thermocycled. The posts were removed from the root canals using a calibrated testing machine in tensile mode. The mean dislodging force for group 1 was 190.46 N and for group 2 was 183.8 N, with standard deviations of 54.9 and 56.0 N respectively. The t-test indicated no significant difference between the two groups. Failure of the posts occurred mainly within the resin layer. This study showed that under experimental conditions there was no statistically significant difference between Sealapex sealer and Tubli-Seal sealer on the retention of glass fibre posts using a resin cement.

Effect of Zoe Temporary Restoration on Resin-Dentin Bond Strength Using Different Adhesive Strategies

STATEMENT OF THE PROBLEM

Eugenol is a radical scavenger that inhibits the polymerization of resin materials. Little is known about the effect of a eugenol-containing temporary restorative material on the resin-dentin bond strength of adhesive systems that partially dissolves and modifies the smear layer.

PURPOSE OF THE STUDY

The aim of this study was to evaluate the effect of eugenol-containing temporary restoration (zinc oxide eugenol [ZOE]) on the resin-dentin microshear bond strength of etch-and-rinse and self-etch adhesives.

MATERIAL AND METHODS

The roots of 18 human molars were removed and the crowns of the teeth were transversally sectioned into two halves. The dentin surfaces were embedded in acrylic resin. Half of the samples were stored while the remaining specimens were restored with eugenol-containing temporary restoration. After 24 hours, the ZOE restoration was mechanically removed and dentin surfaces were ultrasonically cleaned. Dentin surfaces were treated with one of the following adhesives: Single Bond, Clearfil SE, and iBond. Six cylinders of Z250 (0.5 mm high and 0.75 mm in diameter) were applied to each bonded dentin surface using a tygon tube. After storage for 24 hours, the specimens were subjected to micro-shear testing. The data was subjected to a two-way analysis of variance and Tukey's test (alpha=0.05).

RESULTS

Similar bond strength values were obtained for Single Bond (p=0.48) either in the control or in the ZOE-treated group. For both self-etch systems, the bond strength in the ZOE-treated group was statistically lower than the control group (p < 0.01).

CONCLUSIONS

Although the prior use of eugenol-containing temporary restoration (IRM) affects the resin-dentin bond strength of the etch-and-rinse Single Bond, a more pronounced reduction on bond strength was observed for the two self-etch systems evaluated (iBond, Clearfil SE Bond). CLINICAL SIGNIFICANCE Eugenol-containing provisional restorations (IRM) should not be used prior to the placement of resin restorations bonded with the two-step etch-and-rinse Single Bond and the self-etch adhesives systems iBond and Clearfil SE Bond.

Effects of a ferric chloride primer on collagen-depleted dentin bonding between tri-n-butylborane initiated self-curing resin and dentin

This study was designed to evaluate the micro-tensile bond strength between a carboxylic resin and dentin, when the dentin surface was modified with an experimental dentin primer. The three primers tested were ED primer II (ED), 0.3% ferric chloride aqueous solution (FE), and ED containing 0.3% ferric chloride (ED/FE). Three commercial dentin conditioners [40% phosphoric acid, 10% NaOCl, and 10% citric acid with 3% ferric chloride (10-3)] were also used. The coronal surfaces of extracted human molars were ground flat to dentin. The dentin surfaces were treated with phosphoric acid, NaOCl, or with one of the primers. The 10-3 was used without phosphoric acid or NaOCl as a control. A composite material rod was bonded to the dentin surface with 4-META/MMA-TBB resin. After 24-h immersion in 37 degrees C distilled water, 0.9 mm x 0.9 mm composite-dentin beams cut from the bonded specimens were stressed to failure in tension at 0.6 mm/min. The bond strengths were also evaluated after 5000 thermocycles. The bond strength of the group ED/FE was significantly higher than those of the 10-3, ED, and FE. After 5000 thermocycling, 10-3, ED and FE showed significant decrease in bond strength, although no significant decrease was seen for ED/FE. It was concluded that dentin surface treatment with phosphoric acid, NaOCl, and the ED/FE primer improved the bonding (p < 0.05) between 4-META/MMA-TBB resin and dentin, with or without thermocycling, while the bond strengths in the control group fell 34% following 5000 thermocycles.

Immediate Dentin Sealing: A Fundamental Procedure for Indirect Bonded Restorations

The purpose of this article is to review evidence-based principles that could help optimize dentin bonding for indirect composite and porcelain restorations. More than 30 articles were reviewed, most of them addressing the specific situation of dentin bonding for indirect restorations. It appears that the combined results of this data plus clinical experience suggest the need for a revision in the dentin bonding procedure. Immediate application and polymerization of the dentin bonding agent to the freshly cut dentin, prior to impression taking, is recommended. This new application procedure, the so-called immediate dentin sealing (IDS), appears to achieve improved bond strength, fewer gap formations, decreased bacterial leakage, and reduced dentin sensitivity. The use of filled adhesive resins (low elastic modulus liner) facilitates the clinical and technical aspects of IDS. This rational approach to adhesion also has a positive influence on tooth structure preservation, patient comfort, and long-term survival of indirect bonded restorations.

CLINICAL SIGNIFICANCE

Tooth preparation for indirect bonded restorations (eg, composite/ceramic inlays, onlays, and veneers) can generate significant dentin exposures. It is recommended to seal these freshly cut dentin surfaces with a dentin bonding agent (DBA) immediately following tooth preparation, before taking impression. A three-step total-etch DBA with a filled adhesive resin is recommended for this specific purpose. The major advantages, as well as the technical challenges of this procedure, are presented in detail.

Marginal adaptation and microtensile bond strength of composite indirect restorations bonded to dentin treated with adhesive and low-viscosity composite

OBJECTIVES

This study evaluated the marginal adaptation of composite indirect restorations bonded with dual curing resin cement after different strategies to seal dentin. Different bonding techniques associated or not with a low-viscosity composite resin (LVCR) were utilized. In addition, the bond strength between composite resin and pre-sealed dentin was evaluated in the buccal and pulpal walls of class I cavities, prepared for indirect restorations.

METHODS

Thirty-three freshly extracted human molars were used for this study, divided into three groups (n=11) representing different techniques to seal dentin-(Group 1) Conventional technique: the adhesive system was applied and polymerized just before the cementation of the indirect restoration; (Group 2) Dual bonding technique: a first layer of the adhesive system was applied and polymerized just after preparation, and a second layer just before the final cementation; (Group 3) Resin coating technique: a LVCR was applied and polymerized after the first layer of the adhesive system, and before the impression. A further application of the adhesive system was performed before the placement of the restoration. The restorations were polished and a solution of acid red propylene-glycol was dropped on each specimen's occlusal surface for 10 s. The dye penetrations were captured under stereoscopic lens and the images were transferred to a computer with a measurement program, in order to determine the extension of the dye penetration. The microtensile bond strength test (muTBS) was applied on pulpal (P) and buccal (B) walls of the restorations for Groups 1-3. The subgroups for muTBS were: Group 1P (n=13); Group 1B (n=7); Group 2P (n=6); Group 2B (n=14); Group 3P (n=14); Group 3B (n=15). All specimens were sectioned to obtain an area of 0.8 mm2. The specimens were mounted on a microtensile device and fractured using a universal testing machine at a cross-head speed of 1mm/min. Failure modes were analyzed by SEM. One-way ANOVA and multiple-comparison Tukey's test were used for statistical analysis of the marginal adaptation scores and muTBS test. Non-parametrical Kruskal-Wallis test was used for failure mode analysis.

RESULTS

Group 3 showed a significantly higher mean value of marginal dye penetration (45.59) when compared to Groups 1 (8.44) and 2 (18.92). For pulpal walls, Group 1P showed significantly higher mean muTBS (25.93+/-2.27) when compared to Groups 2P (14.71+/-1.78) and 3P (16.07+/-2.81). There was no statistical difference between Groups 2P and 3P. For buccal walls, Group 2B presented significantly higher mean muTBS (23.29+/-1.42), and Group 1B the lowest mean values (11.37+/-1.14). The failure mode analysis presented a considerable variation, according to the treatment and to the wall.

SIGNIFICANCE

The results of this study indicated that a previous sealing of dentin using the adhesive system, followed by a second application just before the cementation, is an effective alternative technique, since it maintains the marginal adaptation of indirect composite resin restorations, and improves the bond strength at the interface on buccal walls, which are the most critical regions for the long-term durability of these procedures.

Immediate dentin sealing improves bond strength of indirect restorations

STATEMENT OF PROBLEM

Delayed dentin sealing is traditionally performed with indirect restorations. With this technique, dentin is sealed after the provisional phase at the cementation appointment. It was demonstrated that this chronology does not provide optimal conditions for bonding procedures. Immediate dentin sealing (IDS) is a new approach in which dentin is sealed immediately following tooth preparation, before making the impression.

PURPOSE

The purpose of this study was to determine whether there were differences in microtensile bond strength to human dentin using IDS technique compared to delayed dentin sealing (DDS).

MATERIAL AND METHODS

Fifteen freshly extracted human molars were obtained and divided into 3 groups of 5 teeth. A 3-step etch-and-rinse dentin bonding agent (DBA) (OptiBond FL) was used for all groups. The control (C) specimens were prepared using a direct immediate bonding technique. The DDS specimens were prepared using an indirect approach with DDS. Preparation of the IDS specimens also used an indirect approach with IDS immediately following preparation. All teeth were prepared for a nontrimming microtensile bond strength test. Specimens were stored in water for 24 hours. Eleven beams (0.9 x 0.9 x 11 mm) from each tooth were selected for testing. Bond strength data (MPa) were analyzed with a Kruskal-Wallis test, and post hoc comparison was done using the Mann-Whitney U test (alpha=.05). Specimens were also evaluated for mode of fracture using scanning electron microscope (SEM) analysis.

RESULTS

The mean microtensile bond strengths of C and IDS groups were not statistically different from one another at 55.06 and 58.25 MPa, respectively. The bond strength for DDS specimens, at 11.58 MPa, was statistically different (P=.0081) from the other 2 groups. Microscopic evaluation of failure modes indicated that most failures in the DDS group were interfacial, whereas failures in the C and IDS groups were both cohesive and interfacial. SEM analysis indicated that for C and IDS specimens, failure was mixed within the adhesive and cohesively failed dentin. For DDS specimens, failure was generally at the top of the hybrid layer in the adhesive. SEM analysis of intact slabs demonstrated a well-organized hybrid layer 3 to 5 microm thick for the C and IDS groups. For DDS specimens the hybrid layer presented a marked disruption with the overlying resin.

CONCLUSIONS

When preparing teeth for indirect bonded restorations, IDS with a 3-step etch-and-rinse filled DBA, prior to impression making, results in improved microtensile bond strength compared to DDS. This technique also eliminates any concerns regarding the film thickness of the dentin sealant.

Effect of the dentin cleansing techniques on dentin wetting and on the bond strength of a resin luting agent

STATEMENT OF PROBLEM

Remnants of the provisional cement on prepared teeth may have an adverse effect on the performance of the definitive luting agent.

PURPOSE

This in vitro study investigated the effect of different dentin cleansing techniques on the bond strength of a resin luting agent and dentin wetting.

MATERIAL AND METHODS

Sixty buccal or lingual coronal portions of human molar teeth were mounted, with the buccal or lingual surfaces up, in acrylic resin blocks. The specimens were prepared until the dentin was exposed and a eugenol-containing provisional cement (Temp Bond) was applied to the dentin surfaces. After mechanical removal of the cement with a carving instrument, specimens were divided into 6 groups of 10 specimens each. The dentin surfaces of the specimens were treated with 1 of 5 cleansing techniques: Group S, cleansing agent (Sikko Tim); Group C, cleansing agent (Cavity Cleanser); Group O, rotary instrumentation (OptiClean); Group OS, rotary instrument preceding Sikko Tim; and Group OC, rotary instrumentation preceding Cavity Cleanser. The remaning 10 specimens were untreated and served as controls (CT). An adhesive resin luting agent (Variolink II) was applied to all specimens. Shear bond strength (MPa) was measured using a universal testing machine at a 0.5 mm/min crosshead speed. To measure the contact angle, another 6 groups (n=5) were prepared using the same methods. Contact angle measurements were performed to assess wettability using the Axisymmetric Drop Shape Analysis-Contact Diameter (ADSA-CD) technique. Wettability measurements were made with water. Data were statistically analyzed by 1-way analysis of variance with Tukey HSD tests (alpha=.05). The effect of the dentin cleansing techniques on removing the provisional cement from the dentin surface was examined with scanning electron microscope (SEM).

RESULTS

Specimens cleaned with all techniques showed stronger shear bond strength values than control specimens (P<.001), with the exception of C specimens. The surface cleansing techniques tested affected the dentin wetting significantly in comparison with the control group (P<.001), except for the C and the O groups. There was no significant difference in wetting between the groups C and O. The SEM observations demonstrated that the dentin cleansing techniques left differing amounts of provisional cement remnants.

CONCLUSION

Specimens treated with only the cleansing agent Sikko Tim showed the highest bond strength, likely due to the solvent effect of Sikko Tim on the removal of provisional cement. The lowest bond strength was obtained with the rotary instrument. It was concluded that the provisional cement could plug the dentinal tubules into which the resin luting agent penetrates.

Influence of temporary cement remnant and surface cleaning method on bond strength to dentin of a composite luting system

The aim of the current study was to evaluate the influence of polycarboxylate temporary cement remaining on the dentin surface on the bond strength of a composite luting system. An acrylic resin plate was luted to bovine dentin with a polycarboxylate temporary cement (HY-Bond Temporary Cement Hard, HYB). The temporary cement was not used for the control groups. After removing the temporary cement with an excavator, dentin specimens were divided into five groups; 1) no subsequent treatment, 2) cleaning with a rotational brush (RTB), 3) cleaning with a rotational brush and non-fluoridated flour of pumice, 4) sweeping with an air scaler, and 5) treated with a sonic toothbrush. A silane-treated ceramic disk (IPS Empress) was bonded to each dentin specimen with a composite luting system (Panavia F). Shear testing results showed that the RTB groups exhibited the highest bond strength regardless of the use of temporary cement (P < 0.05). The use of a rotational brush with water coolant is recommended to achieve ideal bond strength between the Panavia F luting system and dentin to which HYB temporary cement was primarily applied.

Improvement of the bond strength of 4-META/MMA-TBB resin to collagen-depleted dentin

It has been reported that the tensile bond strength between the 4-META/MMA-TBB resin and dentin pretreated with 10% citric/3% ferric chloride solution decreased after immersion in water for 2 years. The current study investigated the effect of an experimental dentin conditioner on the bonding of 4-META/MMA-TBB resin to dentin after thermocycling. The experimental conditioner was an aqueous solution of 10% ascorbic acid and 5% ferric chloride (Exp). Human teeth were prepared to expose flat dentin surfaces. These were treated sequentially with 40% phosphoric acid, 10% sodium hypochlorite, and the experimental conditioner. A commercially available dentin conditioner, an aqueous solution of 10% citric/3% ferric chloride (10-3) was used for a control group. Stainless steel rods were bonded to the pretreated dentin surfaces with the use of the 4-META/MMA-TBB resin. Tensile bond strengths were determined after 0, 5,000, 10,000, 20,000 themocycles. All data were analyzed by ANOVA, and differences among groups were analyzed by Duncan's new multiple range test (n = 10, p < 0.05). The experimental group showed no significant decrease in bond strength through 20,000 thermocycles, while the control group exhibited significant decrease after 10,000 thermocycles. Mean bond strength of the experimental groups were significantly higher than those of the control group at both 10,000 and 20,000 thermocycles. A hybrid layer could not be identified in SEM micrographs of the experimental groups. 10-3-conditioned specimen SEMs displayed crack formation between the adhesive resin and a hybrid layer. The experimental dentin pretreatment improved the bond strength of a 4-META/MMA-TBB resin to human dentin compared to 10-3 treatment after thermocycling.

Evaluation of a novel dentin bonding system compared to commercial bonding system

OBJECTIVE

The aim of the current study was to compare the bond strength of an experimental bonding system with commercial bonding systems.

MATERIAL AND METHODS

An aqueous solution of 10% ascorbic acid and 5% ferric chloride was prepared as an experimental conditioner (Exp). The flattened human dentin surfaces were conditioned with phosphoric acid, NaOCl, and Exp. They were bonded to a stainless steel rod with 4-META/MMA-TBB resin. Super-Bond C&B (10-3), Panavia Fluoro Cement (Panavia), Panavia Fluoro Cement with AD gel (AD/Panavia), and All-Bond 2 system (All-Bond 2) were also used. After immersion in water for 24 h, half of the specimens of each group were tested for tensile bond strength, and the remaining specimen groups were subjected to 10,000 cycles of thermo-cycling prior to tensile testing. All of the data were analysed by ANOVA and a post hoc test. In addition, two thermo-cycled specimens (10-3/10,000, Exp/10,000) were prepared for photomicrography.

RESULTS

The bond strengths of Exp and AD/Panavia groups showed no decrease after 10,000 thermo-cycles, although those of 10-3, Panavia, and All-Bond groups decreased significantly after thermo-cycling. SEM micrographs exhibited that cracks and voids can be observed in the 10-3/10,000 specimen at the interface of the adhesive resin and the hybrid layer, although neither a hybrid layer nor cracks can be seen in the Exp/10,000 specimen.

CONCLUSION

Comparison of the tensile bond strengths for all adhesive resins revealed that the novel dentin bond system with experimental conditioner and Panavia Fluoro Cement with AD gel exhibited the most durable bonding after thermo-cycling.

In vivo evaluation of three cleansing techniques for prepared abutment teeth

STATEMENT OF PROBLEM

Residual provisional cement and debris on prepared teeth may have the potential to negatively influence the performance of the definitive luting agent.

PURPOSE

This in vivo study quantified the adherence of provisional cement to abutment teeth prepared with 1 of 2 textures (coarse or fine) and cleaned with 1 of 3 common cleansing techniques.

MATERIAL AND METHODS

One hundred ten provisional restorations in 22 patients were luted to maxillary anterior abutment teeth. The teeth were prepared for complete veneer restorations with either a coarse-grit diamond bur or a coarse-grit diamond bur followed by a fine-grit diamond bur. After removal of the restoration, abutment teeth were randomly cleansed with either a No. 23 dental explorer and air-water spray, a prophy cup with fine flour pumice, or a cotton pellet soaked in chlorhexidine gluconate, 0.12%. After the abutments were cleansed, they were evaluated intraorally under a light microscope (magnification, x64) by 2 blinded examiners. The teeth were given scores based on the number of specks of residual cement found on the surface after the cleansing techniques were performed. Pearson correlation coefficients (alpha=.96), 3-way analysis of variance, and post hoc Scheffé tests (P<.05) were used to analyze the data.

RESULTS

As determined with Pearson correlation coefficient, the interexaminer reliability was alpha=.96. Three-way analysis of variance revealed significant effects for the cleansing techniques but not for the interaction between cleansing techniques and preparation texture. A post hoc Scheffé test showed that the pumice cleansing technique (1.8 specks/tooth) was significantly better than the explorer or the cotton pellet/chlorhexidine gluconate technique (3.6 and 3.5 specks/tooth, respectively) (P<.05).

CONCLUSION

Within the limitations of this study, abutment teeth cleansed with a prophy cup and flour pumice exhibited the least amount of residual provisional cement.

Crowns and other extra-coronal restorations: resin-bonded metal restorations

Resin-bonded metal restorations is the final part of the series. Cast metal restorations which rely on adhesion for attachment to teeth are attractive because of their potential to be much more conservative of tooth structure than conventional crowns which rely on preparation features providing macromechanical resistance and retention.