Influence of dentin pretreatment with synthetic hydroxyapatite application on the bond strength of fiber posts luted with 10-methacryloyloxydecyl dihydrogen phosphate-containing luting systems

Comparative evaluation of desensitizing agents on shear bond strength of zirconia to dentin

BACKGROUND

The purpose of the study is to evaluate the effect of 7 different desensitizing agents on the shear bond strength (SBS) of zirconia restorations to dentin with a self-adhesive resin cement and determine the failure modes.

METHODS

Eighty molars' occlusal surfaces were ground to expose dentin and were randomly divided into 8 groups (n = 10): 1. Gluma (HEMA/Glutaraldehyde) 2. Bifluoride (Sodium Fluoride/Calcium Fluoride) 3. Admira (Bis-GMA/HEMA) 4. Smart Protect (Glutaraldehyde) 5. Teethmate (Tetracalcium phosphate, Dicalcium phosphate) 6. Clinpro White (Sodium fluoride) 7. BisBlock (Oxalic acid) and 8. Control (No-treatment). After applying the agent, a self-adhesive resin cement (Rely-X U200) was used to lute zirconia discs (4 mm height and 4 mm diameter) to dentin. After stored in distilled water at 37 °C for 24 h, all groups were thermocycled for 2500 cycles between 5 ± 2 °C and 55 ± 2 °C. Specimens were submitted to SBS test with a universal testing machine at a crosshead speed of 0.5 mm/min until failure. SBS values were compared with ANOVA. Post-hoc multiple comparisons were performed with Dunnett T3. The failure modes of specimens were examined with stereomicroscope at a magnification of 20X and the distribution of the failure modes were evaluated with Pearson Chi-Square test.

RESULTS

Regarding mean SBS values in MPa's; Admira (10.70 ± 3.99), Smart Protect (9.62 ± 3.93), and Gluma (8.90 ± 3.76) treatments showed higher SBS values compared to control group (p < .05) according to ANOVA. The SBS values of Teethmate (5.31 ± 2.37) and Clinpro White (4.32 ± 2.44) were higher than control group but the difference was not found significant (p > .05). BisBlock (2.33 ± 1.94) and Bifluouride (1.60 ± 1.47) groups showed the lowest SBS values but their difference between control group was not found statistically significant (p > .05). Most specimens showed adhesive failure but no statistically significant difference was found in the distributions of failure modes according to Chi-square test.

CONCLUSION

Within the limitation of the study; Admira, Smart Protect, and Gluma increased the SBS of the zirconia restorations to dentin and can be recommended to use on prepared dentin surfaces prior to the cementation.

Aspects of glass and hybridization protocols for bonding of fiber posts to root dentine

This study evaluated bond strength of glass fiber posts to root dentin using push-out (PO) and diametral compression (DC), testing glycolic acid as a conditioner and varying dentin moisture. An additional aim was to test whether DC can be an alternative test to PO for bond strength assessment. Eighty bovine teeth were divided into eight groups (n = 10) defined by the use of either 37% glycolic acid or 37% phosphoric acid (PA) on moist or wet dentin before bonding with either Adapter SingleBond/RelyX ARC or One Step Plus/Duo-Link Bisco. Each tooth provided discs with an internal diameter of 2 mm, external diameter of 5 mm, and height of 2 mm, which underwent PO and DC. Finite element analysis (FEA) was carried out on 3D models. When analyzing PO results through linear regression, the highest values of bond strength were observed using glycolic acid on wet dentin in the cervical and middle thirds of the teeth. Analyzing DC results, the only statistical influence on values was the dental thirds. The scatterplot of the DC results and the PO bond strength values indicated no relationship between the results of the two tests (r = 0.03; p = 0.64). PO test detected more sensitive changes in bond strength values than DC.

Digital Workflow for Producing Hybrid Posts and Cores

A novel and straightforward digital workflow is described to aid clinicians in producing in-office hybrid posts and cores. The method is based on scanning and using the basic module of a computer-assisted design and computer-assisted manufacturing (CAD-CAM) software program for dental applications. The applicability of the technique in a digital workflow is the simplicity of in-office production of a hybrid post and core that can be delivered to the patient in the same day.

Influence of photodynamic therapy, different final irrigants, and ultrasonic activation on the bond strength of glass fiber posts to root dentin

OBJECTIVE

To evaluate the influence of photodynamic therapy (PDT), different final irrigants, and ultrasonic activation (US) on the bond strength of glass fiber posts (GFP) to root dentin.

METHODS

One hundred twenty bovine roots were divided into 12 groups according to PDT application, the type of final endodontic irrigant, and US. The samples were divided into 12 groups (n = 10): G1-DW(distilled water); G2-DW+US; G3-17% EDTA; G4-17% EDTA+US; G5-17% GA (glycolic acid); G6-17% GA+US; G7-PDT+DW; G8-PDT+DW+US; G9-PDT+17% EDTA; G10-PDT+17% EDTA+US; G11-PDT+17% GA; G12-PDT+17% GA+US. After cementing the glass fiber posts with resin cement, roots were sectioned into 2-mm-thick slices. One slice from the cervical third and another from the middle third were used for the push out test (PO), and the other two for the diametral compression test (DC). Thus, 10 samples were obtained per third for each mechanical test (n = 10). Kruskal-Wallis and Student-Newman-Keuls tests were used to analyze PO and DC data, and Pearson's correlation test was used to verify the relationship between the variables. Failure patterns were analyzed with chi-square test.

RESULTS

Significant differences were found in the PO test among the experimental groups (p < 0.001; power=1.00). PDT improved bond strength when using EDTA. PDT and US increased bond strength when using GA. Favorable failure patterns occurred more frequently in Group GA+US. There was no correlation between data obtained with PO and DC tests (r = 0.112; p = 0.729).

CONCLUSION

PDT provided the highest bond strength values of GFP to root dentin when associated with GA and US or when associated only with EDTA.

A laboratory study to assess the physical, mechanical, and 3-D structural properties of nano-apatite grafted glass fibre-based endodontic posts

AIM

To fabricate and characterize nano-hydroxyapatite (nHA) grafted and non-grafted glass fibre-based endodontic posts.

METHODOLOGY

Experimental glass fibre posts were fabricated using silanized nHA grafted (ex-HA) and non-grafted glass fibre (ex-P) reinforced resins. The structural analysis and morphological patterns were analysed with Fourier transform infrared spectroscopy and scanning electron microscopy, respectively. EverStick^® glass fibre posts (eS) were used as a control group. The degree of conversion, flexural strength, and flexural modulus was investigated and the fractured structure was evaluated with a scanning electron microscope. Root canals were prepared in human extracted teeth restored with experimental and control posts. The push-out bond strength was evaluated with radicular dentine at days 7, 30, and 90, and the presence of voids at the interface were measured at day 1, 7, 30, and 90 with micro-computed tomography. The Shapiro-Wilk test and one-way ANOVA post-hoc Tukey's test were performed. The level of significance was set at 0.05.

RESULTS

The SEM and FTIR confirmed the presence of a silane-coupling agent on the glass fibres. The ex-HA post had a significantly lower degree of conversion compared to the ex-P post (p = .0008), but a significantly higher conversion than the eS post (p = .0014). The maximum flexural strength value was obtained with the ex-HA post with an insignificant difference (p = .366) compared to ex-P post and a significant difference (p = .029) compared to the eS post. The flexural modulus of ex-HA, ex-P, and eS posts were significantly different (p = .037). Similarly, the ex-HA post had a significantly higher push-out bond strength at days 7 and 30 (p = .037) compared to the ex-P and eS posts. The volume of voids had a nonlinear behaviour amongst the groups with no significant difference between the posts.

CONCLUSION

The fabrication of the experimental posts was successful and the ex-HA post had greater flexural strength and push-out bond strength compared to the ex-P post. The degree of conversion of the ex-HA post was lower than the ex-P and eS posts. The volume of voids of ex-HA and ex-P posts was lower than that of eS posts.

Post-Space Treatment Influences the Bond Strength In Endodontically Treated Teeth: A Systematic Review and Meta-Analysis of In Vitro Studies

OBJECTIVES

This systematic review of in vitro studies investigated the influence of the post-space treatment used to remove the smear layer on the bond strength of the post to root canal dentin.

METHODS AND MATERIALS

In vitro studies included in this study were identified from PubMed/MEDLINE, Lilacs, and Scopus databases up until March 2019, without limits on publication year or language. Two reviewers independently selected the studies based on the inclusion and exclusion criteria, extracted the data, and evaluated the risk of bias of all studies. A random effects model was used for pairwise meta-analyses (control vs. post-space preparation groups) at a significance level of p<0.05.

RESULTS

Of the 2,832 potentially eligible studies, 453 studies were selected for full-text analysis, and 75 were included in this systematic review. Only one study was considered to have a low risk of bias. Overall, post-space treatment significantly improves the bond strength to root canal dentin (p<0.00001).

CONCLUSION

Post-space treatment has a positive influence on the bond strength of the post to root canal dentin. In this review, the post-space treatments that improve the adhesive resistance of the post were ethanol, sodium hypochlorite, and ethylene diamine tetra-acetic acid (NaOCl + EDTA), NaOCl + EDTA + ultrasound, erbium-doped yttrium aluminium garnet laser (Er:YAG laser), neodymium-doped yttrium aluminium garnet laser (Nd:YAG laser), and diode laser.

Bioactive Materials for Direct and Indirect Restorations: Concepts and Applications

Currently, minimally invasive restorations could be made in dentistry applying adhesive materials and adhesion principles to the dental structures. Following this philosophy, endodontic interventions have been avoided largely, preserving hard tissues, and maintaining dental vitality. Advances in biologically favorable bioactive materials enabled clinicans to induce repair and regeneration of dental tissues. Such materials are primarily used for pulp protection and cementation of indirect restorations. This review highlights current bioactive materials available, principles of bioactivity and their mechanisms of action.

Adhesion of Two New Glass Fiber Post Systems Cemented with Self-Adhesive Resin Cements

The aim of this in vitro study was to evaluate the adhesion strength of two new fiber post systems (FiberSite™ Post and Cytec™ Blanco Post) cemented with two different adhesive resin cements (Panavia™ SA and Maxcem™ Elite). Root canals of sixty extracted human mandibular premolars were prepared using ProTaper Universal™ rotary files (Dentsply Sirona Endodontics, York, PA, USA). The root canals were irrigated with 5.25% sodium hypochlorite (NaOCl) during instrumentation. After root canal preparation, the canals were irrigated with 2 mL of 17% EDTA (1 min), followed by 2 mL of 5.25% (5 min) NaOCI, and 2 mL saline. The root canals were dried with paper points and divided randomly into two study groups (n = 30) according to the type of post system: Group 1, FiberSite™ Post (MegaDental, Partanna, Italy); and group 2, Cytec™ Blanco Post (Hahnenkratt, Königsbach-Stein, Germany), with one of the two adhesive resin cements: Subgroup A, Panavia™ SA Cement Plus Automix (Kuraray, Osaka, Japan); subgroup B, Maxcem™ Elite (Kerr, Orange, CA, USA). Following thermocycling, the adhesion strength was evaluated using the push-out adhesion (bond) strength test. Fractographic analysis was performed using stereomicroscope. The data were analyzed using two-way analysis of variance (p = 0.05). The adhesion strength values of both the posts were significantly higher when cemented with subgroup B (Maxcem™ Elite). The highest adhesion strength value was demonstrated by group 1B (FiberSite™ post cemented with Maxcem™ Elite cement). The type of post did not have a significant impact on the bond strength values for either cement material.