Dual-cure Resin Cement Research Articles

Assessment of Dual-Cure Resin Cement Properties of Microhardness and Water Sorption/Solubility through Various Shades of Monolithic Zirconia

Assessment of Dual-Cure Resin Cement Properties of Microhardness and Water Sorption/Solubility through Various Shades of Monolithic Zirconia

Static Loading of Different Intraradicular Preparation Depths of Trinia Endocrowns in Maxillary Canines.

The aim of this study is to compare the fracture resistance of canine teeth restored using TRINIA Endocrowns with three different types of preparations (2, 3, and 4 intracanal preparations). Thirty maxillary-extracted canines were collected. All teeth were fixed in orthodontic acrylic resin and decapitated at the level of the proximal cemento-enamel junction (CEJ). After being endodontically treated, specimens were distributed equally between 3 groups (n = 10) with different preparation depths (GT: 2 mm Intraradicular Preparation, GH: 3 mm Intraradicular Preparation, GF: 4 mm Intraradicular Preparation). Thirty TRINIA endocrowns were dry milled. After surface treatment, all endocrowns were bonded to their corresponding roots using Permaflo a dual-cure resin cement. Each specimen was then fixed in the lower part of a universal testing machine with a load cell of 5 KN, at an angle of 45 degrees to the tooth long-axis at 0.5 mm/min crosshead speed. Failure loads were recorded in Newton's. Data were recorded, organized, and statistically investigated. Shapiro-Wilk tests revealed that the data were not normally distributed. Descriptive statistics revealed a high mean fracture resistance of GH (647 N), then GT (475.6 N), and finally GF (353.9 N). The Kruskal-Wallis test revealed a significant difference that existed between the groups being studied (p = 0.036). TRINIA endocrowns with intracanal preparations of 2 and 3 mm provide more promising fracture resistance than those with intracanal preparations of 4 mm as a way of treating of root-canal-treated maxillary canines. TRINIA endocrowns (2 and 3 mm intracanal preparations) are as promising as fiber posts and all ceramic crowns in terms of fracture resistance. TRINIA endocrowns with 2 mm intracanal preparations are mostly reparable after failure, but those of 3 and 4 mm are mostly irreparable after failure. Modifying endocrowns to have intraradicular projections, simulating Nayyar core, may improve the success and longevity of endocrowns in anterior teeth. How to cite this article: Alahmad AM, Alenezi AY, Rayyan M, et al. Static Loading of Different Intraradicular Preparation Depths of Trinia Endocrowns in Maxillary Canines. J Contemp Dent Pract 2024;25(6):575-580.

Fracture resistance and fractographic analysis of pressable glass-ceramics with different partial coverage designs for maxillary premolars

BackgroundPartial coverage concepts have met the main goal of conservative dentistry. Vonlays, which combine features of veneers and onlays, are a recent alternative to full coverage designs and overlay partial coverage restorations. This in vitro study was conducted to compare the fracture resistance of the newly introduced pressable zirconia-reinforced lithium silicate with pressable lithium disilicate ceramic and to determine the optimal preparation design for partial coverage on upper premolars.MethodsFifty-two duplicated epoxy resin dies were prepared following vonlay and overlay preparation guidelines. For each preparation (n = 26), the specimens were divided into two subgroups to be restored with lithium disilicate (IPS e.max Press) or zirconia-reinforced lithium silicate (Vita Ambria) (n = 13 each). Ceramic vonlays and overlays were bonded using dual cure resin cement, subjected to thermomechanical fatigue, and the load to fracture was tested by using a universal testing machine. The specimens were fractographically analyzed via scanning electron microscopy (SEM). The normality of the fracture resistance data was checked using the Shapiro‒Wilk test and Q‒Q plots, and two-way ANOVA was used to assess the effect of the type of preparation and ceramic material on the fracture resistance.ResultsThe group of overlays restored with zirconia-reinforced lithium silicate showed the highest mean fracture load (1218.69 N), while the group of vonlays restored with lithium disilicate had the lowest mean fracture resistance (967.15 N). The effect of preparation design and material type on fracture resistance was significant for both factors, p = 0.003 and p < 0.0001, respectively. Different features of the fracture surfaces, such as arrest lines, hackles, and directions of crack propagation, were observed.ConclusionsZirconia-reinforced lithium silicate exhibited greater resistance to fracture compared to lithium disilicate, making it a potential substitute for partial coverage restorations. Additionally, the overlay showed superior fracture resistance when compared to the vonlay preparation design.

Effect of resin cement viscosities and surface roughness on shear bond strength of conditioned polymer infiltrated ceramic network

BackgroundHybrid ceramics bonding with the dentinal substrate is crucial for clinical success and longevity. To enhance adhesion, the surface of ceramic restorations is modified through various conditioning techniques AimEffect of Different Surface Conditioners Erbium-doped yttrium aluminum garnet (ER: YAG) laser and Low-level laser therapy (LLLT) activated Methylene blue (MB) on the surface roughness (Ra) and shear bond strength (SBS) of Polymer infiltrating ceramic network (PICN) discs bonded using different viscosity resin cement before and after thermal aging. Material and MethodsOne hundred and fifty human central incisors and one hundred and fifty-three PICN discs were prepared. PICN discs were randomly allocated into three groups based on the surface conditioning(n = 51) Group 1:10 % HF acid-S, Group 2: LLLT (MB), and Group 3: Er: YAG laser. Following conditioning Ra scores of ten samples were performed. Surface topography of samples was performed using a scanning electron microscope (SEM). Bonding of forty PICN discs from each conditioning group was performed with high (A) or low viscosity (B) dual-curing resin cement (n = 20 each). Each subgroup was divided into two cohorts and subjected to varying storage conditions. The SBS test and failure mode analysis were performed using a universal testing machine and stereomicroscope. Descriptive statistics of SBS and Ra for each group were analyzed using ANOVA and Tukey post hoc tests. HF acid-S attained the highest Ra scores. ResultsGroup 1A (HF-S+HIGH) samples achieved the highest SBS values at baseline. Group 3A, on the other hand, displayed the lowest bond score (Er: YAG laser+HIGH) after thermal aging. Intergroup comparison analysis at baseline unveiled that Group 1A and Group 1B (HF(S) + LOW) displayed no significant difference in their bond strength scores (p>0.05). Following artificial aging, it was observed that Group 2A (LLLT (MB) + HIGH) and Group 3A (Er:YAG laser + HIGH) ) presented comparable SBS(p > 0.05). Thermal aging decreased SBS significantly in all groups. PICN conditioned with HF-S results in high surface roughness. ConclusionPICN conditioned with HF acid with silane and bonded with low-viscosity resin cement to the dentinal substrate is preferable. Aging influences SBS.

Clinical Evaluation of Metal Dental Prostheses in Captive Wild Felids.

Captive felids are prone to dental fractures, and the recommended treatment involves endodontics (root canal treatment), prosthodontics (coronal restoration), or tooth extraction. A single-unit dental prosthesis can restore the crown of a tooth whose structure has been partially or completely lost. Nine animals out of 35 captive wild felids kept under human care in 7 different Brazilian institutions were selected for the study. The animals selected included the little spotted cat (Leopardus tigrinus), ocelot (L. pardalis), margay cat (L. wiedii), pampas cat (L. colocolo), jaguarundi cat (Puma yagouaroundi), puma (P. concolor), jaguar (Panthera onca), lion (P. leo), and tiger (P. tigris). Nineteen canine prosthodontic crowns (18 full and one 3/4) were cemented using dual-cure resin cement and their feasibility was evaluated for 30 months. Fourteen (73%) remained fixed to the tooth and 5 (27%) were lost after the evaluation period. This study aimed to assess the longevity of prosthodontic crowns in the canine teeth of wild felids. Furthermore, it aimed to determine the functionality and longevity of teeth which had received prosthodontic crowns.

Comparative evaluation of dual-cure resin (TheraCal PT) and Biodentine in coronal pulpotomy of patients with symptoms indicative of irreversible pulpitis: A randomized clinical trial.

New and innovative materials are being marketed for the treatment of coronal pulpotomy. It is crucial to compare their efficacy with already-established materials. TheraCal PT (TP) is such a new material that studies are scarce. This study aim to compare and evaluate the outcome of coronal pulpotomy using Biodentine and a newly introduced calcium silicate-based dual-cure resin cement, TP, in patients with symptoms of irreversible pulpitis. Sixty patients with exposed carious pulp and symptomatic irreversible pulpitis were included, aged 18-40, randomly allocated to two groups: TP (group I) and Biodentine (group II). Coronal pulpotomy was performed following a standardized protocol, with TP or Biodentine applied accordingly. The pain was recorded using Visual Analog Scale preoperatively for up to 1 week. Success was assessed clinically and radiographically for up to 12 months. The data were analyzed using the Friedman test and the Mann-Whitney U-test. Intragroup pain was analyzed using the Wilcoxon signed-rank test. Among 60 patients, intervention was done in 53. By removing dropout patients, 47 were analyzed, with 38 available for follow-up at 3, 6, and 12 months. The Biodentine group exhibited a 12-month success rate of 84%, while the TP group revealed 77.3%, with statistically insignificant difference (P = 0.563). TP can be effectively utilized as a pulpotomy material in cases of symptomatic irreversible pulpitis in mature permanent teeth, offering rapid setting and ease of use, although Biodentine yielded slightly better results in this study.

Photon-Induced Photo-Acoustic Streaming vs. Shock Wave-Enhanced Emission Photo-Acoustic Streaming-The Effect of Three Final Irrigation Protocols on the Bond Strength of an Individually Formed Fiber Post.

(1) Background: This study aimed to evaluate how laser-activated irrigation (LAI) influences the retention of a fiber post when used before an endodontic filling, as well as after post space preparation. (2) Materials and Methods: Sixty freshly extracted human incisors were selected. The teeth were randomly assigned to three groups-CONVENTIONAL (CONV), PIPS or SWEEPS-and treated endodontically. Each group received irrigation with 1 × 5 mL EDTA (17%) and 3 × 5 mL NaOCl (5.25%). In the first group, the irrigants were not activated, while in the second and third group, LAI was adopted using PIPS and SWEEPS protocols (Lightwalker from Fotona, Ljubliana, Slovenia). After post space preparation, each group received the same irrigation protocol initially established. Sticky posts (everStick Post, GC AUSTRIA GmbH Swiss) were individually adapted to the corresponding post spaces and cemented using dual cure resin cement (Gradia Core, GC Austria GmbH Swiss). All specimens were vertically embedded into self-curing acrylate (Duracryl plus, Spofa Dent, Europe), and each was sectioned into three segments of type A and type B samples for debonding through push-out and pull-out tests. The results were statistically analyzed. (3) Results: The pull-out test showed the superiority of the SWEEPS group, with a mean fracture force of 133.0 ± 50.7 N, followed by the PIPS group, with 102 N, with a lower standard deviation of ± 34.5 N. The CONV group registered the lowest fracture force. Concerning the push-out test, the SWEEPS group showed superior shear stress in comparison to the other two groups (13.45 ± 4.29 MPa); the CONV group was inferior, with shear tension values of 8.31 ± 4.67 MPa. (4) Conclusions: It can be stated that the SWEEPS and PIPS protocols resulted in considerably higher fiber post retention than the conventional method, whereas the SWEEPS protocol was superior to the PIPS protocol.

Clinical Performance of Computer-Aided Design (CAD)/Computer-Aided Manufacturing (CAM) Resin Nanoceramic Endocrowns in Restoring Molars: An In Vivo Study.

Background It is difficult to determine the optimal method for restoring endodontically treated teeth, as several factors affect this decision. Functional requirements and the amount of remaining coronal tissue are considered the most important factors in choosing the best restoration for those teeth. Endocrown was introduced as a conservative alternative for endodontically treated and coronally damaged teeth. Aim The aim of this study is to assess the clinical performance of the nanoceramic system for molar endocrowns by evaluating color change, gingival condition, prosthesis integrity, and the presence of secondary caries. Materials and methods The sample consisted of 20 endocrowns. The teeth were prepared with at least 2 mm of wall thickness and a cavity depth of 4 mm from the occlusal surface. The final impression was taken, and the prostheses were adhered using dual-cure resin cement. It was clinically evaluated according to clinical success criteria (United States Public Health Service) in terms of color stability, gingival indexes, integrity of the restoration, and the presence of secondary caries after a week, three months, six months, and a year. The statistical study was conducted using IBM SPSS Statistics for Windows, Version 23.0 (Released 2015; IBM Corp., Armonk, NY, USA), and the results were considered statistically significant at the 95% level of significance. The Friedman test was used to study the significance of the differences in the average values of color change, plaque index, and the integrity of the prostheses during follow-up periods. Results The study showed a gradual increase in the degree of color change with follow-up periods. Furthermore, there was no significant difference in the incidence of gingival changes, the integrity of the prosthetic margins, or the occurrence of secondary caries during the follow-up periods. Conclusions Within the limitations of this study, an endocrown made of CeraSmart nanoceramic is an acceptable option for crowning decayed and endodontic-treated molars with acceptable clinical performance.

Comparative evaluation of incorporation of ferrule in premolars endocrown designs to check any alterations in their fracture resistance: A pilot study.

Endocrown preparation of endodontically treated teeth as final restoration has been extensively studied for different teeth. Bindl et al. questioned the application of endocrowns for premolars due to the pulp chamber space's smaller dimensions, which diminish bonding surface area. The addition of ferrule into the endocrown preparations of premolars has not been extensively studied. Comparative evaluation of incorporation of the ferrule in premolars endocrown designs to check any alterations in their fracture resistance. The sample consisted of 40 maxillary first premolars without cracks or caries, extracted for orthodontic or periodontal purposes. The teeth were individually mounted with cold-cure acrylic resin. Group A: Composite endocrown without ferrule and Group B: Composite endocrown with ferrule. An endocrown former was prepared with elastomeric polyvinyl siloxane material (GC Exaclear). Endocrowns were then prepared with dual-cure core build-up composite-Core-x flow (Dentsply Maillefer, Switzerland) using the endocrown former so that morphologically, they all were almost identical. Endocrowns are cemented by dual-cure resin cement following manufacturer instructions. The fracture resistance of endocrowns with and without ferrule was evaluated and compared. The data were tabulated in Microsoft Excel and analyzed with SPSS version 24 software. The variables were presented with mean, standard deviation, and independent t-test. The P ≤ 0.05 is considered statistically significant. Group B (with ferrule) showed higher fracture resistance (622.06 N) than Group A (537.59 N) (without ferrule). Independent t-test showed that the difference was statistically significant (P = 0.008). Comparing the failure load findings, it could be concluded that ferrule-containing endocrown needed greater loads than ordinary endocrown restorations for failure.

THE INFLUENCE OF ABUTMENT SURFACE TREATMENT ON PULL-OFF BOND STRENGTH BETWEEN (5)YTTRIA STABILIZED ZIRCONIA CROWN AND TITANIUM IMPLANT ABUTMENT

ABSTRACT Aim: The objective of this research was to evaluate the effect of mechanical method and energetic method of surface treatments for Ti-abutment base (Ti-Base, Dentium/Korea) on the pull-off bond strength with (5)Y-TZP crown. Materials and Methods: : Forty titanium implant abutments were used in this study and randomly assigned to four groups (n = 10 for each group) according surface treatment methods of titanium abutment: group (1) act as control without surface treatment for Ti-abutment, group (2) bur surface treatment of Ti-abutment, group (3) sandblast (50-µm aluminum oxide) surface treatment for Ti-abutment, group (4) plasma surface treatment for Ti-abutment. Then, forty implant analogs were placed in the center of acrylic mold. After that abutment was tightened on the each analog with (35 N/cm) torque . Forty (5)Y-TZP crowns fabricated by CAD/CAM system that had special design with occlusal O-hole cemented to all abutments using Allcem dual-cure resin cement. All specimens were then subjected to thermos-cycling with (5000) cycles. With a universal testing machine record pull-off bond strength for all samples, Collected data were analyzed using a one-way analysis of variance at a significance level of (p &lt; 0.01) . Results:, The bur treated abutment (group 2) group showed the highest bond strength values, followed by sandblast treated abutment (group 3) and plasma treated abutment (group 4). Control group was the lowest value of tensile strength. Conclusion: Surface treatments of Ti-abutment had observed effect on pull-off (tensile bond strength) between Ti-abutment and (5)Y-TZP crown Bur and sandblast cause roughness of surface and increase bond strength , plasma cause reactive surface for increasing tensile bond strength.

A Push-out Bond Strength Study and Interface Analysis of New Porous Titanium Dental Post Luted with Resin Cement

This study aimed to compare the push-out bond strength (PBS) between a new porous titanium post (PTP) and other marketed dental posts cemented with two types of dual-cure resin cement. A total of 96 extracted single-rooted human teeth were recruited. Four types of dental posts (n = 24 each), namely: stainless steel post (SSP), commercially-pure titanium post (CTP), fibre glass post (FGP), and PTP were cemented with two types of resin cements (RelyX U200 and ParaCore) and then sectioned at coronal and middle root levels. The specimens were subjected to a PBS test at a crosshead speed of 0.5 mm/min. The interface analysis was performed using a stereomicroscope and scanning electron microscope. A p-value &lt; 0.05 was considered significant for all statistical tests. PBS recordings showed that the highest PBS mean value in RelyX group was 2.68±1.10 MPa for PTP. The differences in PBS between PTP and SSP and FGP were not significant (p = 0.098 and p = 0.075, respectively). The null hypothesis for RelyX group at both coronal and middle sections of the root was retained (p &gt; 0.05). No failure at the post-cement interface was found in the PTP group, which was founder superior over the other posts (no gap for this interface was observed). The PTP showed similar bonding strength and adhesion to the other tested posts when using RelyX U200 cement. The PTP can be considered a new alternative option for the dental post system.

The Effect of Surface Properties of Different Types of Post Materials on Fracture Type

Introduction and Aim Considering the advantages and disadvantages of different clinical situations, the surface characteristics of the post materials significantly affect the connection of the post material with dentin. In this study, the surface properties of PEEK posts, which are not yet widely used as post materials, were examined in terms of their effects on dentin bonding. Method 66 extracted upper central incisor-type human teeth that had undergone canal treatment with single and straight root canals were used. Posts were produced ) (n=11) from metal, fiber, and PEEK materials to form six groups (CP-0, CP-1, FP-0, FP-1, PP-0, and PP-1). The surface roughness of each post was examined by using a tactile profilometer. Zirconium full crowns, compatible with the central maxillary incisor anatomy, were produced for 66 samples with completed post-core production and polymerized using dual-cure resin cement (Monobond plus Vivadent). Subsequently, the samples were subjected to fracture strength testing at a 135-degree angle to the long axis of the tooth from the palatal side of the zirconium crown at a speed of 0.02 cm/min using a universal testing machine. After the test, the samples were classified into three groups based on the type of fracture: adhesive, cohesive, and mixed. One-way ANOVA and Pearson’s chi-squared tests were used for statistical analysis. Results The surface roughness value of the PEEK post group (1.42 ± 0.21) was significantly lower than that of the metal and fiber post groups. Although no significant difference was found in terms of the fracture type, the adhesive failure rate was higher in the PEEK post group (P

The Impact of Bonding Agents and Bone Defects on the Fracture Resistance of Reattached Vertically Root-Fractured Teeth

Many patients experience vertical root fractures, and clinicians often consider conservative treatment options like reattaching the fractured root segments. The study investigated the impact of different bonding agents on the fracture resistance of rebonded vertically fractured teeth with various alveolar bone defects. Human premolar teeth with a single root were sectioned and reattached using dual-cure resin cement (DCRC), resin-modified glass ionomer (RMGI), and cyanoacrylate. The reattached teeth were then restored with a resin fiber post, composite resin core, and full veneer metal copings. These teeth were embedded in acrylic blocks with angular, V-shaped, and step-shaped bone defects to simulate various alveolar bone conditions. After subjecting the samples to thermal cycling, the fracture resistance was evaluated using a universal testing machine. Teeth samples reattached with RMGI exhibited a higher average fracture resistance. The study also found that DCRC proved to be an effective bonding agent for VRF teeth. However, cyanoacrylate-rebonded teeth exhibited the lowest fracture resistance. The V-shaped defects had a significant impact on the fracture resistance of reattached VRF teeth, with largely unfavorable fractures observed in these cases. Predominantly favorable fractures were observed in the teeth treated with RMGI. The fracture loads in both RMGI and DCRC groups exceeded the expected masticatory load.

Analysis of the Marginal Continuity in Different Designs of Monolithic Zirconia Inlay-Retained Fixed Dental Prostheses: An In Vitro Study.

To evaluate the marginal integrity of three inlay-retained fixed dental prosthesis (IRFDP) designs fabricated using monolithic zirconia. In total, 30 IRFDPs were fabricated using 4-YTZP monolithic zirconia and randomly divided into three groups according to the cavity design. Groups ID2 and ID1.5 received an inlay cavity preparation, which includes a proximal box and an occlusal extension with a depth of 2 mm or 1.5 mm, respectively. Group PB received a proximal box cavity preparation without an occlusal extension. The restorations were fabricated and cemented using a dual-cure resin cement (Panavia V5) and subjected to an equivalent of 5 years of aging. The specimens were evaluated under an SEM to measure marginal continuity before and after the aging process. During the whole 5-year aging process, no specimens showed signs of cracking, fracture, or loss of retention in any restorations. In the SEM analysis, most marginal defects observed in the restorations were areas of microgaps at the tooth/cement interface (TC) or zirconia/cement interface (ZC), resulting in loss of adaptation. There was a significant difference between the groups after the aging process at both the TC (F = 4.762, P < .05) and ZC (F = 6.975, P < .05), with Group ID2 presenting the best performance. There was a significant difference between TC and ZC in all groups (P < .05), with ZC presenting more gaps in all groups. Inlay cavity designs including a proximal box and an occlusal extension exhibited better marginal stability than a proximal box without occlusal extension.

Comparative bonding performance of coronal dentin disks and CAD/CAM resin composite disks for biological restoration: The impact of resin-coating technique.

This study evaluated the bonding performance of coronal dentin disks, designed for biological restoration, and CAD/CAM resin composite disks when bonded to flat dentin surfaces using dual-cure resin cements, with and without a resin-coating (RC) technique. Three distinct groups were established within the non-RC group, each using one of the two types of resin cements in a self-adhesive mode: one-step self-etch adhesive (1-SEA) without light-cure, 1-SEA with light-cure, and a separate group using an alternate cement. Within the RC group, a subgroup was established for each cement. The microtensile bond strength (μTBS) of the disk-dentin beam was tested after 0 and 10,000 thermocycles in a 5°C/55°C. No significant μTBS difference was observed among the non-RC groups. However, when using RC, the μTBSs of coronal dentin disks significantly exceeded those of CAD/CAM resin composite disks. Thermocycle aging did not affect μTBS in any of the bonding methods, except in self-adhesive mode.

Impact of CAD/CAM Material Thickness and Translucency on the Polymerization of Dual-Cure Resin Cement in Endocrowns.

The objective of this study is to evaluate the impact of the thickness and translucency of various computer-aided design/computer-aided manufacturing (CAD/CAM) materials on the polymerization of dual-cure resin cement in endocrown restorations. Three commercially available CAD/CAM materials-lithium disilicate glass (e.max CAD), resin composite (CERASMART), and a polymer-infiltrated ceramic network (ENAMIC)-were cut into plates with five different thicknesses (1.5, 3.5, 5.5, 7.5, and 9.5 mm) in both high-translucency (HT) and low-translucency (LT) grades. Panavia V5, a commercial dual-cure resin cement, was polymerized through each plate by light irradiation. Post-polymerization treatment was performed by aging at 37 °C for 24 h under light-shielding conditions. The degree of conversion and Vickers hardness measurements were used to characterize the polymerization of the cement. The findings revealed a significant decrease in both the degree of conversion and Vickers hardness with increasing thickness across all CAD/CAM materials. Notably, while the differences in the degree of conversion and Vickers hardness between the HT and LT grades of each material were significant immediately after photoirradiation, these differences became smaller after post-polymerization treatment. Significant differences were observed between samples with a 1.5 mm thickness (conventional crowns) and those with a 5.5 mm or greater thickness (endocrowns), even after post-polymerization treatment. These results suggest that dual-cure resin cement in endocrown restorations undergoes insufficient polymerization.

Influence of Thickness and Translucency of Lithium Disilicate Ceramic on the Degree of Conversion of Resin Cements with Different Initiators.

The degree of conversion (DC) of resin cements can be affected by ceramics, and by the type of resin cement. The purpose was to evaluate the influence of thickness and translucencies of lithium disilicate ceramic on the DC of resin cements: two light-cure (Variolink LC; NX3 LC) and one dual-cure (NX3 Dual). IPS e.max Press ceramic (A2) discs were prepared in 4 thicknesses (0.3, 0.5, 1.0, and 1.5 mm) and in 3 translucencies: HT (high translucency), LT (low translucency), and MO (medium opacity). Subsequently, 234 samples of resin cement (5 x 1 mm) were light-cured through those ceramic discs. The DC was assessed by Fourier Transform Infrared Spectroscopy (FTIR). Ceramic thicknesses decreased DC of NX3 Dual through HT-1.0 and HT 1.5 (p=0.005). Between translucencies, only MO-0.3 affected Variolink LC DC (p=0.018). There was difference among light- and dual-cured resin cements (p=0.001). Increasing thickness and opacity lead to a decrease in the DC of all resin cements, with a significantly lower DC value in NX3 Dual (HT-1.0; HT-1.5), and in Variolink LC (MO- 0.3). Light- and dual-cured resin cements were different among each other. NX3 Dual achieved a significantly lower value than its counterpart NX3 LC.

Evaluation of Bond Strength of Three Glass Fiber Post-systems Cemented to Large Root Canals.

The aim of this study was to evaluate the push-out bond strength and the failure mode of single adjustable posts (SPLENDOR SAP), anatomical posts (AP), or computer-aided design/computer-aided manufacturing (CAD-CAM) posts cemented to flared root canal dentin with self-adhesive dual-cure resin cement. Thirty single-rooted premolars received endodontic treatment with gutta-percha and a calcium hydroxide-based endodontic cement. After 24 hours, the canal spaces were enlarged with burs. The tooth specimens were divided equally into three groups (n=10), according to the glass fiber post (GFP) system: AP-prefabricated GFP (Reforpost #2, Angelus) was relined with composite resin (Filtek Z350 XT, 3M ESPE); SPLENDOR SAP-GFP was used with a glass fiber sleeve to adjust the adaptation (Splendor SAP, Angelus); and CAD-CAM-a resin pattern was obtained and scanned to produce a CAD-CAM GFP (Fiber CAD Lab, Angelus) milled using a subtractive technique. The three GFP systems were cemented with self-adhesive resin cement (Rely X U200, 3M ESPE). The roots were fixed to an acrylic resin plate used to section them into specimens of cervical, middle, and apical thirds. Then, the slices were attached to a universal testing machine to perform the push- out test at a speed of 0.5 mm/min and a load of 50 Kgf. The posttest specimens were examined under a stereoscopic microscope to evaluate the failure mode. The bond strength variable was analyzed using a generalized linear model, following a split-plot design. Failure mode analysis was performed using Fisher exact test. The significance level adopted was 5%. There was no significant difference among the GFP systems or among the thirds, in terms of bond strength (p>0.05), nor was there any significant association between the systems and the failure mode (p>0.05). Most specimens presented mixed or adhesive failure between resin cement and dentin. It was concluded that the bond strength to flared root dentin was not influenced by the GFP system or the root third.

Laser-texturing and traditional surface modification to improve the adhesion of glass fiber-reinforced composite posts to resin cements

ObjectivesThe aim of this study was to perform an experimental evaluation of the synergistic effects of laser-texturing and different traditional surface modification approaches to improve the adhesion of glass fiber-reinforced composite (GFRC) posts to resin-matrix cements used in endodontically treated teeth rehabilitation. MethodsOne hundred and ten freshly extracted mandibular single-rooted premolars were endodontically treated and groups of specimens were divided according to the GFRC cementation after different surface treatment, as follow (n = 10): silane-based conditioning (SIL); 9.7 % HF acid-etching (HF); 35 % H2O2 etching (H2O2); grit-blasting (GB); HF plus H2O2 etching (HFH2O2); 6 W Nd:YAG laser-texturing (L6W); 4.5 W Nd:YAG laser-texturing (L4.5W); 3 W Nd:YAG laser-texturing (L3W); 3 W Nd:YAG plus 35 % H2O2 (L3WH2O2); 3 W Nd:YAG plus SIL (L3WSIL); and untreated (C). GFRC posts were cemented into the tooth root canals using a dual-cured resin cement. Then, specimens were cross-sectioned and mechanically assessed by push-out bond strength tests. Specimens were inspected by optical microscopy and scanning electron microscopy (SEM) at magnification from × 30 up to × 2000. The failure mode was recorded by microscopic analyses after the bond strenght tests. ResultsSurface analyses of the GFRC posts showed a rough and retentive morphological aspect with a removal of the outer epoxy matrix layer and exposure of glass fibers after laser-texturing, grit-blasting, or etching under 35 % H2O2. The highest bond strength values at 21.8 MPa was recorded for GFRC posts after laser-texturing on 3W plus silane-based conditioning followed by the group etched with 35 % H2O2 (20.5 MPa). The failure mode was microscopically characterized as cohesive and mixed pathways. The lowest bond strength values around 5 and 9 MPa and adhesive failure were recorded for the untreated GFRC group or specimens etched with HF. ConclusionsThe combination of acidic etching and silane conditioning with laser-texturing at moderate intensity promoted an adequate surface modification of GFRC posts and increased adhesion to a resin-matrix cement. Such combination of physicochemical approaches can enhance the long-term mechanical behavior of the restorative interface at endodontically treated teeth. Clinical relevanceCombining traditional and novel physicochemical approaches can provide promising adhesion pathways for glass fiber-reinforced composite posts to resin-matrix cements. A high mechanical interlocking of the resin-matrix cements and the stable retention of the teeth root intracanal posts can decrease the risks of clinical failures by fracture and detachment of the intraradicular interface.

Prolonged post-washing in ethanol decreases bond strength of additively manufactured crown materials

ObjectivesThis study aimed to investigate the effect of post-washing duration and crown thickness on the bond strength between additively manufactured crown materials and dental cement in vitro. MethodsRectangular-shaped specimens of two thicknesses (1.5 and 2.0 mm) were additively manufactured from permanent VarseoSmile Crown (VC) and long-term temporary NextDent (ND) materials. The specimens were post-washed (n = 160) in ethanol for 5 min, 10 min, 1 h, and 8 h then cemented with dual-cure resin cement. Twenty PMMA (TC) were milled as a control. A chevron-notch test was performed to measure the maximum load until failure (N). Interfacial bond strength (J/m2) was calculated and statistically analysed. The mode of failure was analysed by scanning electron microscopy (SEM). ResultsThere was a significant difference in the bond strength between all groups (p < 0.01). VC at 1.5mm thickness post-washed for 10 min showed the highest mean bond strength (1.77 ±0.96 J/m2) while VC at 2.0mm thickness post-washed for 8 h showed the lowest (0.22 ±0.10 J/m2). Exposure to ethanol for 8 h resulted in lower bond strength. Within the type of material, there were no differences in bond strength between the thicknesses when post-washed for the same duration. ConclusionsProlonged post-washing of AM crown materials can significantly decrease the bond strength to resin cement. There were no differences between the permanent and long-term temporary AM materials. When post-washed for 5 min, AM materials observed comparable or higher bond strength values compared to PMMA. Clinical significanceThe output of this research serves as a guide for dental practitioners, emphasising the importance of adhering to correct post-washing procedures for optimal bond strength of additively manufactured crown materials.