The effect of intracanal placement of various medicaments on the bond strength of three calcium silicate-based cements to root canal dentin

This study aimed to evaluate the effect of intracanal placement of various medicaments on the bond strength of ProRooT MTA, Biodentine, and Endosequence root repair material (ERRM) putty. Ninety extracted human mandibular premolar teeth were decoronated and instrumented using Protaper Next rotary system and #1 to #6 Peeso reamers. The prepared teeth were randomly divided into six groups according to the intracanal medicaments: Group 1: double antibiotic paste (DAP) consisting of metronidazole and ciprofloxacin; Group 2: Triple antibiotic paste (TAP) with cefaclor; Group 3: TAPwith clindamycin; Group 4: amoxicillin and clavulanic acid (Augmentin®); Group 5: calcium hydroxide (CH); Group 6: control (no medicament) (n = 15). Parallel transverse sections were obtained in the coronal to the apical direction (4 slices/ tooth) and were divided into three subgroups according to the cements: Group A: ProRoot MTA; Group B: Biodentine; Group C: ERRM (n = 20 slices/subgroup). A push-out test was used to measure bond strength. Data were analyzed using two-way analysis of variance and Tukey’s post hoc test. The bond strength was significantly lower for DAP and TAPs than for Augmentin®, CH, or the control (p < 0.05). Biodentine and ERRM had significantly higher bond strength values than ProRooT MTA (p < 0.05) regardless of the intracanal medicaments tested, while no significant difference existed between Biodentine and ERRM (p > 0.05). While the application of DAP or TAPs decreased the bond strength, application of CH or Augmentin® did not. ERRM and Biodentine had higher bond strength values than ProRoot MTA.     

Long-term bond strength of fiber posts cement to dentin with self-adhesive or conventional resin cements

The aim of this study was to evaluate the immediate and the long-term push-out bond strength of glass fiber posts (GFP) cemented with conventional or self-adhesive dual-curing resin cements, at different root depths. Prior to cementation, the GFP (Reforpost #3, Angelus) were etched with 37% phosphoric acid for 30 s followed by silane for 1 min. Thirty canine roots were divided into two groups (n = 15) according to resin cement type: ARC – dual resin cement (RelyX ARC/3M ESPE) combined with an three-step etch-and-rinse adhesive (Adper Scotch Bond Multi-Purpose Plus 3M/ESPE) or U200 – self-adhesive resin cement (RelyX U200/3M ESPE). The manufacturer’s instructions were followed. After 48 h, the roots were cross-sectioned at three different depths, resulting in serial slices corresponding to the cervical, middle, and apical root thirds. Slices were randomly divided into two groups, according to the period of water storage prior to push-out bond strength analysis: 48 h or 180 days. The data (MPa) were analyzed using three-way ANOVA for randomized blocks (p < 0.05), which showed no significant interaction between the three factors (p = 0.716). The main study factors were also proven not significant (cement: p = 0.711; time: 0.288; root third: p = 0.646). In conclusion, root depth, cement type (self-adhesive or conventional), and storage in water for 180 days did not influence the bond strength of GFP to intracanal dentin.     

The effects of chelation on the adhesion of two different root canal sealers

Objective: This study aims to evaluate alterations in the root canal dentin after irrigation with EDTA, HEBP, and Chitosan in order to determine the push-out bond strengths of the different root canal sealers on altered dentin surfaces. Materials And Methods: Crowns of 70 maxillary single-rooted teeth were removed to obtain a standardized length of 16 mm. The canals were instrumented using rotary files and the step back technique. The master apical file used in this study was #40. The subgroups were determined based on the chelation agent and the material of the root canal sealer that was used (17% EDTA, 18% HEPB, 0.2% Chitosan, Well Root ST (WRST) or AH Plus). Three slices with 1 mm thickness were cut from the root thirds of each tooth and subjected to a push-out test. The data (MPa) were analyzed using a one-way ANOVA and a Duncan’s multiple comparison test at a level of α = 0.05. Finally, scanning electron microscope (SEM) photographs were taken. Results: Groups that used WRST exhibited significantly higher push-out bond strength values in all subgroups independent of the irrigant that was used (ANOVA, p < 0.05). Group 1 showed higher push-out bond strength than the other AH Plus subgroups. Conclusion: The EDTA improved the push-out bond strength of the AH Plus. The WRST root canal sealer had the highest push-out bond strength and did not depend on the irrigant used.     

Comparative evaluation of push-out bond strength of Neo MTA Plus with Biodentine and white ProRoot MTA

Objective: The aim of this in vitro study was to evaluate the bond strength of a new calcium silicate cement, Neo MTA Plus (Avalon Biomed Inc. Bradenton, FL, U.S.A) by comparing ProRoot MTA and Biodentine.

Material and Methods: Sixty dentin slices were instrumented to achieve a diameter of 1.3 mm. Group 1: white ProRoot MTA, group 2: Biodentine, group 3: Neo MTA Plus – G (powder mixed with gel), group 4: Neo MTA Plus – W (powder mixed with distilled water) were loaded into cavities. The push-out bond strength values were measured. Data were analyzed using Welch ANOVA with Bonferroni correction p = 0.05. Failure modes (adhesive, cohesive, and mixture) were analyzed.

Results: The highest bond strength value was recorded in Neo MTA Plus mixed with gel (5.23 ± 1.78 MPa), whereas white ProRoot MTA (2.57 ± 0.66 MPa) had the lowest. Bond strength values of Neo MTA Plus mixed either with gel or with distilled water were statistically different from both white ProRoot MTA and Biodentine (2.61 ± 0.70 MPa) (p < 0.05). Adhesive failure was predominantly observed in all groups.

Conclusion: Neo MTA Plus could be considered as alternatives to the ProRoot MTA and Biodentine due to its better performance in bonding to root dentin.     

Effect of Er,Cr:YSGG laser surface conditioning on the adhesion of fiber- reinforced composite and zirconia intraradicular posts to the root dentin

This study evaluated the influence of Er,Cr:YSGG laser surface conditioning on push-out bond strength of different root posts to the root dentin. Extracted (N = 27, n = 9 per group) and endodontically treated human mandibular premolars were prepared to receive the posts. Three types of posts, namely quartz fiber (D), glass fiber (S), and zirconium dioxide post (C) were luted with resin cement. The posts were randomly assigned to one of the surface conditioning method: (a) No conditioning, control (L0), (b) Er,Cr:YSGG laser at 175 mJ, 3.5 W for 60 s (L1), and (c) at 225 mJ, 4.5 W for 60 s, with 60 μs pulse duration and repetition rate was 20 Hz (L2) irradiation. Six sections (two coronal, two middle, and two apical) were made in each tooth yielding to 1 mm thick specimens. The specimens were stored in distilled water at 37?°C for 24 h and push-out bond strength (MPa) was tested in a Universal Testing Machine (1 mm/min). Data were analyzed using Kruskall–Wallis and Dunns`s post hoc tests (α = 0.05). In group D, both laser treated groups (L1:16.16 ± 19.89; L2:8.24 ± 9.26) presented significantly less bond strength compared to control group (L0:28.3 ± 16.8) (p < 0.001). Mean push-out bond strength values did not significantly differ according to the root segments (coronal, middle, and apical) (p = 0.106). Application of Er,Cr:YSGG laser, with the parameters tested, did not increase the bond strength of zirconium glass fiber and zirconium oxide posts. Laser surface conditioning decreased the bond strength of quartz fiber posts in the root canal.     

Effects of mixing techniques and dentin moisture conditions on push-out bond strength of ProRoot MTA and Biodentine

Objective: To evaluate the influence of manual and mechanical mixing techniques as well as the effects of moisture on the push-out bond strength of ProRoot MTA (Dentsply Tulsa Dental, Tulsa, OK, USA) and Biodentine (Septodont, Saint Maur des Fosses, France) to radicular dentin.

Material and methods: Two hundred and forty dentin discs were assigned into three groups with respect to the moisture condition tested: (1) dry, (2) paper points, (3) wet. The discs were further divided into four subgroups according to the calcium silicate cements (CSCs) and mixing techniques used: (1) ProRoot MTA mixed manually, (2) ProRoot MTA mixed mechanically, (3) Biodentine mixed manually, and (4) Biodentine mixed mechanically. Bond strengths of the cements to root canal dentin were measured using a push-out test setup. The data were statistically analyzed using three-way ANOVA and Bonferroni post hoc test p = 0.05.

Results: The data indicated that the push-out bond strength values were significantly affected by CSCs, mixing techniques, and moisture conditions (p < 0.001). Dry conditions caused a significant decrease in bond strength values for both CSCs (p < 0.001). The mean bond strength of Biodentine was significantly higher than that of ProRoot MTA, regardless of the mixing techniques and moisture conditions (p < 0.001). Mechanical mixing favored bond strength values statistically compared to manual mixing (p < .001).

Conclusion: The mixing techniques and moisture conditions have an effect on the push-out bond strengths of ProRoot MTA and Biodentine. Dry samples and manual mixing of cements deteriorate the push-out bond strengths values.     

The effect of combined use of chitosan and PIPS on push-out bond strength of root canal filling materials

Adhesion of root canal filling materials to root dentin is important for the long-term success of the treatment. Push-out bond strength test is used to evaluate the adhesion capacity of root canal filling materials to root canal walls. The aim of the present study is to compare the bond strength of root canal filling materials to root dentin after irrigation with EDTA, chitosan and the combination of chitosan and PIPS irridation using push-out bond strength test. Forty-eight extracted teeth were resected until 13-mm long roots were obtained. Root canals were prepared with a size-25 OneShape instrument. Samples were divided into three groups each including 15 roots. Group 1: Canals were rinsed with 0.2% chitosan and subjected to laser irridation with PIPS at the same time. Group 2: Canals were rinsed with 0.2% chitosan. Group 3: Canals were rinsed with EDTA. All canals were filled with .06 tapered gutta-percha and AH-plus sealer. One-mm thick slices were taken from coronal, middle and apical one-thirds of the roots. Push-out bond strength was determined using a Universal Testing Machine. One root from each group was observed under SEM to evaluate the degree of smear removal. Statistical analysis was performed with Kruskall-Wallis test. Results showed that bond strength values were statistically similar in overall evaluation for all groups (p > .05). In segmental evaluation, group 1 revealed the highest bond strength in apical one-third compared to other groups (p < .05).     

Effect of calcium hydroxide removal techniques on the bond strength of root canal sealers

To evaluate the influence of calcium-hydroxide(CH) with different vehicles on the push-out bond strength of different canal sealers to radicular dentin. 152 decrowned single-rooted human teeth were used. After preparation of root canals with nickel-titanium rotary files, 8 roots served as control groups. Then, the roots were divided as follows: (1) Calasept and (2) Surepaste (n = 72). Roots were further subgrouped according to the CH removal techniques: (1) %17 ethylenediaminetetraacetic acid (EDTA) + rotary file, (2) %17EDTA + hand file, and (3) %17EDTA (n = 24). Eight roots from each group sectioned longitudinally, divided into two pairs and photographed by stereomicroscope (n = 16). The remaining 16 roots in CH intracanal dressing groups were further divided into 2 subgroups according to the sealer used: (1) AH-Plus-jet and (2) Apexit-Plus (n = 8). Bond strengths of the root canal sealers to root canal dentin were measured using a push-out test setup. The data were statistically analyzed using multivariate analysis of variance p = 0.05. The push-out bond strength values were significantly affected by type of vehicle and the removal techniques (p < 0.05). The mean bond strength of AH-Plus-jet was significantly higher than Apexit-Plus, regardless of type of vehicle and the removal techniques (p < 0.05). There was no difference between vehicles on CH removal (p > 0.05). When examining the removal techniques, only irrigation with %17 EDTA left significantly larger amount of residue (p < 0.05). AH-Plus-jet showed better dislocation resistance than Apexit-Plus. Type of vehicle does not play a fundamental role in the degree of persistence of CH residues on the dentin walls. Instrumentation improves the removal efficiency of CH from root canal.     

The Disk-Specimen Thickness Does Not Influence the Push-Out Bond Strength Results Between Fiber Post and Root Dentin

This study evaluated the effect of different thickness of disk-shaped specimens on the push-out bond strength test. Eighteen lower bovine teeth were sectioned (20 mm) and prepared (15 mm) with the same post system drill (Light Post® #1, Schaumburg, IL, Bisco, USA). The apical third of each specimen was embedded in a plastic matrix filled with an acrylic resin (Dencrilay?, Dencril, Sao Paulo, Brazil). The posts were cleaned with alcohol, silanated (ProSil®, FGM, Joenville, SC, Brazil) and cemented with the RelyX? U100 (3 M ESPE, St. Paul, MN, USA). Each specimen was sectioned into three pieces of differing thicknesses (1, 2, and 4 mm). These disk-samples were allocated into 3 groups (n = 18) and subjected to push-out testing. One-way ANOVA showed no influence of the specimen thickness on the results (p = 0.842). No correlation was observed between thickness and push-out bond strength (Pearson Correlation, r² = 0.0688; P = 0.6209). The push-out bond strength test was not affected by the thickness of the disk-specimens.     

Influence of the ER,CR:YSGG laser and different irrigation methods on push-out bond strength of fiber post

Er,Cr:YSGG lasers are currently being investigated for disinfecting the root canal treatment. The aim of this study was to compare the effects of various irrigation protocols on push-out bond strength of fiber posts. Fifty maxillary anterior teeth were divided into five groups (n = 10) according to the protocol that applied into the post space. Group-1: distilled water, Group-2: 5% NaOCl, Group-3: 2% CHX, Group-4: Er,Cr:YSGG laser (1.5 W, 20 Hz, 85 air, 75 water, 26.7 J/cm²), Group-5: Er,Cr:YSGG laser (1.25 W, 50 Hz, 34 air, 24 water, 12.7 J/cm²). Fiber posts were cemented with resin cement. The remaining part of the root, three slices were obtained from each specimen and push-out test was performed. One-way ANOVA and Duncan’s test at a 5% level of significance were used for the statistical analysis. Post space irradiation with Er,Cr:YSGG laser (1.5 W 20 Hz, 85 air, 75 water, 26.7 J/cm²) increases push-out bond strength of fiber post to root canal dentin. Further investigations are needed to establish and optimize ER,Cr:YSGG laser parameters to increase the push-out bond strength of fiber posts.     

Mechanical properties of flared root canals restored with fiber post and chemically activated resin: study using push-out bond strength and fracture load tests

This study aimed to evaluate the fracture load and push-out bond strength of flared root canals restored with different procedures, including a technique with a fiber post and a chemically activated resin composite. Eighty human canines were selected and treated endodontically. Two methodologies were used: push-out and fracture load. The teeth were divided into four groups: Cast metal core (CMC); PAN (direct anatomic post); PAC (fiber post and accessory posts); and PE (fiber post with chemically activated resin composite). For the fracture load test, the samples were submitted to load application in a universal testing machine. The fracture mode was evaluated visually. Forty other samples were submitted to the push-out test. The fracture load (n = 10) and the bond strength (n = 10) were analyzed by analysis of variance and Tukey tests (α < 0.05). CMC presented the highest fracture load (p < 0.05), and no significant differences were observed in the fracture load values for Groups PAN, PAC, and PE. CMC presented 90% of unfavorable failures; PAN and PAC, the remaining 10% of these failures. PE presented only favorable failures. PAC presented lower push-out bond strength values. The fracture load for CMC procedure was higher than that of the others, but presented 90% unfavorable fractures, indicating the use of any of the glass fiber post techniques evaluated for restoring flared root canals due to favorable fracture modes.     

Degree of conversion and adhesion of methacrylate-based resin cements with phosphonic or phosphoric acid acrylate to glass fiber posts at different regions of intraradicular dentin

This study evaluated the degree of conversion (DC) and adhesion of methacrylate-based resin cements to glass fiber posts at different regions of intraradicular dentin. Single-rooted teeth (N?=?24, n?=?12 per group) were cut at the cement–enamel junction (CEJ), endodontically treated and post space (depth?=?8 mm) was prepared. Teeth were randomly divided into two groups according to the resin cements: (a) Group ML: methacrylate-based cement with phosphonic acid acrylate (Multilink Automix, Ivoclar Vivadent); (b) Group RXU: methacrylate-based cement with phosphoric acid acrylate (RelyX Unicem 2 Automix, 3 M ESPE). Fiber-reinforced composite root posts (RelyX Fiber Post, 3 M ESPE) were cemented according to the manufacturers’ instructions of the resin cements. Root slices of 2-mm thickness (n?=?3 per tooth) were cut below the CEJ 1, 3, and 5 mm apically. The DC of each section was analyzed with micro-Raman spectrometer and push-out test was performed in the Universal Testing Machine (0.5 mm/min). After debonding, all specimens were analyzed using optical microscope to categorize the failure modes. While data (MPa) were statistically evaluated using Kruskal Wallis, Mann–Whitney U tests for DC data 3-way ANOVA and Tukey’s tests were used (α?=?0.05). Regardless of the resin cement type, the mean push-out bond strength results (MPa), were significantly higher for the coronal slices (ML: 9.1?±?2.7; RXU: 7.3?±?4.1) than those of the most apical ones (ML: 7?±?4.9; RXU: 2.89?±?1.5) (p?=?0.002). Resin cement type and (p?p?=?0.002) significantly affected the DC values, while the interaction terms were not significant (p?=?0.606). Overall, DC was significantly higher for ML (67?±?8.2%) than RXU (26?±?8.8%) (p?相似文献   

Bond strength of veneering porcelain to zirconia after different surface treatments

Aim: The aim of this study was to evaluate the effect of various surface treatments on the bond strength of veneering feldspathic porcelain to zirconia. Methods: Fifty yttria-stabilized tetragonal zirconia polycrystalline specimens were divided into five groups (n = 10) according to various surface treatments. The groups were as follows: Group 1: control group with liner application and no further surface treatment; Group 2: air-particle abrasion with 110 μm of alumina (Al₂O₃) particles; Group 3: grinding with a diamond disk; Group 4: Nd:YAG laser irradiation (the laser and the energy parameters were 10 Hz, and 2 W and 200 mJ, and the pulse duration (short pulse) range was up to 180 μs); Group 5: selective infiltration etching (SIE). After surface treatments, a liner application was performed for all surfaces according to the manufacturer’s instructions. Veneering porcelain was applied on zirconia surfaces using a Teflon mold. Shear bond strength was tested using a universal testing machine. The fractured surface morphologies were examined with scanning electron microscopy. The data were statistically analyzed using Mann–Whitney U and Kruskal–Wallis tests (α = .05). Results: The Megapascal values of the bonding groups were as follows: G1 = 8.62 ± 1.12, G2 = 13.87 ± 5.08, G3 = 12.31 ± 3.35, G4 = 17.32 ± 6.16, and G5 = 16.17 ± 4.55. Statistically significant differences were observed between the control group and the other groups (p < 0.05). Group 4 had the highest bond strength while G1 showed the lowest bond strength. No significant differences were found between the Nd:YAG, grinding, sandblasting, and SIE groups. Conclusion: Surface treatments had different effects on the shear bond strength of feldspathic porcelain to zirconia. Surface treatment techniques used in this study can be used on zirconia specimens prior to liner application to obtain an acceptable bond strength of veneering porcelain to zirconia. The effect of Nd:YAG laser irradiation and SIE techniques on bond strength of veneering ceramic to zirconia should be evaluated with further studies.     

Effect of the frequency of mechanical pulses for fatigue aging testing on push-out bond strength between glass fiber posts and root dentin

The aim of this study was to evaluate the influence of the frequency of mechanical pulses during mechanical fatigue aging on bond strength between glass fiber posts and root dentin. Fiber posts were adhesively cemented in 30 bovine roots and the core was built up with composite. All specimens were subjected to mechanical cycling (45° angle; 37 °C; 50 N; 2×10⁶ pulses) at different frequencies: 2, 4, and 8 Hz. After the fatigue, each specimen was submitted to push out test. The bond strength was calculated for data analysis (one-way ANOVA, p = 0.05). The frequency did not affect the push-out (p = 0.7). The main failure mode was between dentin and cement in all groups. The mechanical pulses were not influenced by the bond strength between root dentin and fiber posts. Thus, it is possible to decrease the time-consuming in vitro tests involving posts without damaging the reliability of the test.     

Correlation between sealer penetration into dentinal tubules and bond strength of two new calcium silicate-based and an epoxy resin-based,endodontic sealer

The relationship between sealer penetration into dentinal tubules and the bond strength of two new calcium silicate-based and epoxy resin-based endodontic sealers was evaluated. Thirty recently extracted human maxillary incisors were instrumented and divided into three groups according to the sealer used: (1) AH Plus; (2) iRoot SP; and (3) MTA Fillapex. Sealer penetration into dentinal tubules was measured using CLSM. Then, a universal testing machine was used to compare the push-out bond strengths of the sealers to the root canal dentin. AH Plus and MTA Fillapex exhibited significantly higher sealer penetration than iRoot SP did (p > .05). The push-out bond strengths of AH Plus and iRoot SP were higher than that of MTA Fillapex. We concluded that greater penetration of the sealer into the dentinal tubules was not associated with higher bond strength among the three sealers tested.     

Micro-computerized tomography analysis of cement voids and pull-out strength of glass fiber posts luted with self-adhesive and glass-ionomer cements in the root canal

This study evaluated the pull-out strength of different glass fiber posts and measured volume of cement and voids in the cement in the root canal utilizing micro-computerized tomography (micro-CT) analysis after they were cemented with two different luting cements. Canine teeth (N = 40) were endodontically treated and randomly divided into four groups depending on the fiber post and the cement type (n = 10 per group) as follows: Group RU: (RelyX + RelyX U200), Group PU: (PINpost + RelyX U200), Group RF: (RelyX + FujiCEM 2), Group PF: (PINpost + FujiCEM 2). Each tooth was scanned using micro-CT and the percentage of cement and void volume at the coronal, middle, and apical levels was calculated. Pull-out tests were performed by applying tensile load parallel to the long axis of the posts (0.5 mm/min). Data were analyzed using, ANOVA, Kruskal–Wallis, and Mann–Whitney U tests (α = 0.05). Regardless of cement type, the percentage (%) of cement volume in the RelyX post groups (RU:31–36; RF:29–40) was significantly higher than that in the PINpost groups (PU:19–23; PF:18–22) (p < 0.05). The percentage of void volume at the PINpost groups (PU:6–11; PF:8–13) was significantly lower than that in the RelyX groups (RU:2; RF:3) (p < 0.05). No significant differences were observed in pull-out strength (N) between the four experimental groups (RU:358.8 ± 56.2; RF:299 ± 64.8; PU:311.9 ± 61.3; PF:293.1 ± 91.3) (p > 0.05). The micro-CT analysis demonstrated that the percentage of cement and void volumes vary depending on the type of fiber post and cement used. No correlation between cement, void volume, and pull-out strength was observed.     

Impact of conditioning regimens and time on adhesion of a fiber post to root dentin using two resin cements

The aim of this study was to evaluate the influence of irrigation protocols on the bond strength of a glass fiber post bonded to dentin using two resin cements. In 200 root-filled teeth, post space was prepared and divided into five groups (n?=?40) based on the irrigation protocol: group 1 (3% sodium hypochlorite), group 2 (3% sodium hypochlorite – 17% Ethylene diamine tetraacetic acid), group 3 (a mixture of sodium hypochlorite and etidronic acid), group 4 (sodium hypochlorite – QMix), and group 5 (distilled water). Samples were subdivided into two subgroups (n?= 10) and fiber posts were cemented using subgroup A (Self-adhesive dual-cure resin cement; SEA) or B (dual-cure resin cement following an etch-and-rinse protocol, ER). Push-out bond strength was performed after 24 h and four months (n?= 10) and failure modes were categorized. Statistical analysis of data was carried out by appropriate analyses (p < 0.05). The irrigation protocol and the resin cement had a significant impact on push-out bond strength. Subgroup A group showed lower bond strength than B at both time periods when 3% NaOCl–17% EDTA and 1:1 mixture of 6% NaOCl + 18%EA protocols were used. Three percent NaOCl used in combination with 17% EDTA or QMix significantly decreased the push-out bond strength of ER at the end of four months (p < 0.05). In conclusion, dual-cure resin cements bonded with etch-and-rinse protocol showed highest bond strength when a mixture of NaOCl and etidronic acid was used as root canal irrigant. These values were differentially influenced by time.     

Effect of timing for core preparation,luting cement type and root level on adhesion of fiber posts to intraradicular dentin

This study assessed the effect of timing of core preparation and luting cement on adhesion of fiber-reinforced composite (FRC) posts on different levels of intraradicular dentin when cemented with either conventional dual-polymerized or self-adhesive resin cement. Single-rooted human teeth (N = 80) were endodontically treated and randomly divided into 2 groups (n = 40) according to resin cement: (a) Conventional dual resin cement (Variolink II, V) or (b) Self-adhesive resin cement (RelyX U200, R). They were further divided into two subgroups according to timing of core preparation (n = 20): (a) immediate (i) or (b) delayed (d). FRC posts (Cytec Blanco) were cemented and the roots were sliced into discs at the coronal, middle, and apical levels. Push-out tests were then performed in a Universal Testing Machine (1 mm/min). Data (MPa) were analyzed using three-way ANOVA and Tukey’s tests considering the factors ‘core preparation time’, ‘luting cement’, and ‘root level’ (α = 0.05). Type of luting cement (p < 0.001), time of core preparation (p < 0.001), and root level (p < 0.001) significantly affected the bond strength results. R cement was more significantly affected by core preparation time (Ri: 2.91 ± 1.1; Rd: 4.83 ± 1.68) compared to V cement (Vi: 2.92 ± 1.63; Vd: 2.65 ± 1.6) (p < 0.05). Coronal region demonstrated significantly higher bond strength values than those of middle and apical third in all groups (coronal: 4 ± 1.9; middle: 3.1 ± 1.4; apical: 2.4 ± 1.1) (p < 0.05). Adhesive failure between cement and dentin was the most frequent (64%) followed by adhesive failure between cement and post (18%). Delayed core preparation can improve bond strength of FRC posts to intraradicular dentin when cemented with self-adhesive cement compared to conventional dual-polymerized resin cement.     

Bonding ability of self-adhesive resin-cements after dentin biomodification with hyaluronic acid

Purpose: The present study evaluated the influence of the hyaluronic acid (HA) on the bonding ability of self-adhesive resin cements to dentin regarding the bond strength. Eighty bovine incisors were ground flat to obtain a 2-mm thick slices which received conical preparations. The specimens were randomly distributed into 4 groups (n = 15) according to the dentin pretreatment (1 – control: untreated dentin; 2 – application of HA) and the evaluation time (1 – control: immediate evaluation; 2 – hydrolytic degradation: 6 months of storage in water at 37 °C). Preparations received the application of a self-adhesive resin cement (RelyX U200 or MaxCem Elite). Push-out bond strength test was conducted (0.5 mm/min). The bond strength data was submitted to two-way ANOVA/Tukey’s test (α = 0.05). For U200, no significance was observed when comparing the immediate (24 h) and 6 months means for the control groups (unexposed specimens). Previous application of HA to dentin significantly reduced the bond strength of U200 to dentin in both evaluation times (p < 0.05). HA had no significant influence on the push-out bond strength means for the cement MAX in both evaluation times (p > 0.05). The type 1 failure mode (adhesive mode) occurred in 100% of the specimens, irrespective of the dentin treatment or evaluation times. Pretreatment of dentin with HA produces a material-dependent influence on the push-out bond strength. The bonding ability of RelyX U200 is negatively influenced by the pretreatment of dentin with HA, whereas the biomodification of dentin with this bioactive agent causes no impact for the cement MaxCem Elite.     

Fracture strength of composite resins for endodontically treated molars

Objectives: The purpose of this study was to evaluate the effect of different fabrication techniques on the fracture strength of the composite resin-based inlay restorations of endodontically treated molars. Methods: Sixty mandibular molars were divided into six groups (n = 10) designated according to the treatment as: Group-1: Control group, intact teeth; Group-2: Filtek Ultimate Universal restorative with incremental technique; Group-3: Filtek Bulk Fill Posterior restorative; Group-4: Biodentine with Filtek Ultimate Universal restorative; Group 5: everX Posterior with Filtek Ultimate Universal restorative; and Group-6: Lava Ultimate CAD/CAM restorative. The standard mesio-occluso-distal cavities were prepared and the roots filled for all the teeth, except those of the control group. Following the placement of the restorations, the fracture resistance of the specimens was measured. The data were analyzed by the one-way analysis of variance and Tukey’s post hoc test. Results: While Group-1 (2815.80 N) exhibited significantly higher fracture strength than the other groups (p < 0.05), Groups-2 (2062.20 N), 3 (2166.00 N), 5 (2355.60 N), and 6 (2340.70 N) exhibited statistically similar results (p > 0.05). The Biodentine group (1480.50 N) exhibited significantly lower fracture strength than the rest of the groups (p < 0.05). Conclusions: The CAD/CAM and manual build-up techniques exhibited statistically similar results with the exception of Biodentine, which exhibited a significantly lower in vitro performance compared to the other composites used in the study. The fiber-supported composite everX Posterior increased the fracture strength of the endodontically treated teeth.