Dual Resin Cement Research Articles

Comparison of the microtensile bond strength of direct and indirect resin restorations in the cervical region

ObjectivesTo evaluate in vitro the adhesion system of direct and indirect composite resin restorations in enamel and dentin, in cavities made in the cervical region using microtensile bond strength (μTBS) and to observe the most recurrent types of failure in the different groups. MethodsStandardized cavities were made in the line of the cementoenamel junction (CEJ) in 36 selected human premolars, which were randomly divided into 2 groups. In the Indirect Restorations (IR) group, indirect restorations were cemented in composite resin, using a universal adhesive and dual resin cement, performing selective enamel etching (SEE). In the Direct Restorations (DR) group, direct restorations were made in composite resin, performing SEE and bonding with the universal adhesive. Each specimen was sliced into sections measuring approximately 1 mm2, with enamel and dentin adhesion divided into subgroups DRe, DRd, IRe, and IRd. The sections were subjected to the μTBS test to assess bond strength in both enamel and dentin, comparing direct and indirect restorations in the cervical region. The types of failure in each group were also observed. ResultsThere was no statistically significant difference in μTBS between the DRe and IRe groups (p = 0.314) and also between the DRd and IRd groups (p = 0.145). There was a predominance of adhesive failures. ConclusionsThe bond strength of composite resin restorations was found to be equivalent in enamel and dentin, whether applied directly or indirectly. There was a predominance of adhesive fractures followed by cohesive resin fractures. Clinical significanceThe choice between direct and indirect restorations in the cervical region may consider patient preferences, but with caution, as clinical factors such as operator skill, specific tooth conditions and case complexity are crucial, and both techniques exhibit comparable bond strength.

Bonding and Cleaning Effects of Irrigation Protocols Using Calcium Hypochlorite on the Post-space Radicular Dentin.

This study evaluated the effect of 2.5% sodium hypochlorite (SH) or calcium hypochlorite (CH) submitted to passive ultrasonic irrigation (PUI) or conventional irrigation (CI) on the incidence of residues and the bond strength of the cementation system to post-space dentin. Distilled water (DW) and 2.5% SH followed by 17% EDTA (SH-ED) were used as negative and positive control groups, respectively. The cervical, middle, and apical thirds of the post space were evaluated. One hundred and twenty bovine incisors were endodontically treated and post-space preparation was performed. The specimens were randomly assigned to six groups, according to the solution and irrigation method: DW-CI, SH-ED-CI-SH, SH-CI, SH-PUI, CH-CI, and CH-PUI. The incidence of residues (n=10) over the dentin was evaluated by scores using SEM images. Other specimens were irrigated as previously described and the post cementation was immediately performed using a conventional dual resin cement and a two-step etch-and-rinse adhesive system. Push-out and failure modes were performed for bonding evaluation. Kruskal-Wallis and Dunn test for incidence of residues data and one-way ANOVA and Tukey tests for bond strength data were used at a significance level of 5%. The protocols that showed a lower incidence of residues were: SH-ED-CI-SH, SH-PUI, and CH-PUI for the cervical third and SHED-CI-SH for the middle third (p<0.05). In the apical third, the protocols were similar to each other (p>0.05). Bond strength values were higher after irrigation with DW-CI for all thirds (p<0.05). 2.5% sodium or calcium hypochlorite negatively impacted the adhesion interface and exhibited a greater incidence of residues over the post-space radicular dentin.

Resin inlays as an aesthetic alternative to conventional restorations in posterior teeth. Case study

The systematized professional experience was developed from the analysis of a case treated based on resin inlays as an aesthetic alternative to conventional restorations in posterior teeth. The description of the design and care protocol prior to the attention of the ethics committee is of relevant importance. The objective was to expose the use of composite resin under indirect technique as an alternative to the structural involvement of posterior teeth in a patient treated at the postgraduate clinic of the San Gregorio University of Portoviejo, Manabí, Ecuador. Dies were used as a basis for making the inlays using the incremental technique. To obtain the model, the arch of the selected teeth was impressed with alginate, followed by casting in light silicone for the prepared portion of the tooth and in type III stone plaster for the rest. The cementation process in the oral cavity is carried out with dual resin cement. After analyzing the information collected, an encouraging conclusion is reached that supports the viability and predictability of composite resins indirectly in clinical settings. This, of course, provided that there is a deep knowledge of the advantages and limitations inherent to the various materials involved. Likewise, it is positioned as a reasonable alternative for cases of considerably affected teeth, which, in some instances, could have been considered for more extensive treatments, such as crowns, which involves the removal of remaining dental tissue that could possibly have been preserved

Conventional-, bulk-fill- or flowable-resin composites as prosthetic core build-up: Influence on the load-bearing capacity under fatigue of bonded leucite-reinforced glass-ceramic

This study aimed to evaluate the fatigue performance of simplified ceramic restorations (leucite-reinforced glass ceramic) adhesively cemented onto substrates of different resin composites. Three options from the same commercial line were selected (Tetric N-Line, Ivoclar), classified as Conventional (CRC), Bulk-fill (BRC) and Flowable (FRC), which were used to make discs using a cylindrical metallic device (n = 19; Ø = 10 mm, thickness = 2.0 mm). A total of 57 discs (Ø = 10 mm, thickness = 1.0 mm) were made from CAD/CAM prefabricated blocks of a leucite reinforced glass-ceramic (Empress CAD, Ivoclar) to simulate a monolithic restoration, then were randomly distributed to be bonded on 19 discs of each three different resin composite substrates (CRC; BRC; or FRC) with a dual resin cement (Multilink N; Ivoclar). The samples were subjected to a compression test with a hemispherical stainless-steel piston (Ø = 40 mm) at a monotonic regimen (n = 4; 1 mm/min loading rate and 500 kgf loading cell until fracture). The cyclic fatigue test was performed underwater at a frequency of 20 Hz (n = 15). The first step was applied using 200N for 5000 cycles, followed by increments of 50N at each step of 10,000 until failure. The outcome considered for both tests was the occurrence of radial crack. Specific statistical tests (α = 0.05) were performed for monotonic (One-way ANOVA; Tukey's test) and fatigue data (Kaplan-Meier test; Log-rank test). Fractography of fractured samples were also performed. The FRC group had the lowest failure load in both test regimes (p < 0.05; monotonic: 726.64N; fatigue: 716.67N). There were no differences between the CRC and BRC groups (p > 0.05; monotonic: 989.30 and 990.11N; fatigue: 810.00 and 833.33N, respectively). The same result was obtained considering cycles for fatigue failure (FRC < CRC=BRC). Leucite glass-ceramic bonded to substrates made of flowable resin composite behaves worse mechanically than bonding to conventional or bulk-fill resin composite substrates.

Effect of diode laser irradiation on bond strength of resin cements to high-translucent zirconia.

Treatment of acid-resistance high-translucent zirconia prior to luting procedures is usually carried out with sandblasting. Considering that this process could lead to the formation of cracks on the zirconia surface, laser irradiation became an alternative to sandblasting. The effect of diode laser, however, was never investigated under this context. Therefore, this study aimed to evaluate the effect diode laser irradiation on the bond strength between zirconia and two resin cements after 48-hour and 12-month water aging. Slabs of high-translucent zirconia were sandblasted with 50-µm Al2O3 particles (SB), irradiated with diode laser (DL), or SB+DL. All slabs were etched with 10% hydrofluoric acid and layered with a universal adhesive. Plastic tubes with 0.8-mm internal diameter positioned on treated zirconia surfaces were used as matrices to insert a dual- (DUAL) or a light-cure (LC) resin cement. All specimens were light-cured for 40 seconds at 1000 mW/cm2 and submitted to the µSBS test after 48-hour or 12-month water storage. Data were statistically analyzed with a three-way analysis of variance (p<0.05). The µSBS of DUAL was higher than LC only after 12 months for SB or SB+DL-treated zirconia (p<0.05); in addition, SB+DL resulted in higher µSBS than DL only for DUAL resin cement (p<0.05). The 12-month aging resulted in higher µSBS for DUAL resin cement luted on SB or SB+DL-treated zirconia, as well as for LC luted on DL-treated zirconia (p<0.05). Most of the DUAL specimens presented adhesive failures after 48 hours. After 12 months, the majority of DUAL specimens luted on DL or SB+DL-treated zirconia presented adhesive failures. The use of dual-cure resin cement on sandblasted or sandblasted and diode laser-irradiated zirconia exhibited superior bond strength after aging. Key words:Microshear bond strength, Resin cement, Diode laser, Zirconia, Sandblasting.

Bond strength to dentin of a Polymer-infiltrate ceramic-network material cemented with dual resin cements submitted to different adhesive strategies

The purpose of the present in vitro study is to assess the immediate and long-term bond strength of a self-adhesive and conventional resin luting agents with a new hybrid restorative material to dentin. Blocks of a polymer-infiltrated ceramic-network (PICN) material (VITA Enamic) were cemented to a flat exposed dentin surface through different protocols. The groups were divided considering the combination of resin luting agent and ceramic surface treatment (U200 – Relyx U200 with silane; Ult + Sil – Relyx Ultimate with silane; Ult + SBU – Relyx Ultimate with Scotchbond Universal) and dentin treatment (NT – no dentin treatment; ER – etch-and-rinse with 35 % phosphoric acid) (n = 6). Beam-shaped specimens were obtained by cutting the cemented restorations. Specimens were submitted to microtensile bond strength in a universal testing machine (EMIC). Half of the specimens were tested 24 h after cementation, and the other half were tested after 12 months of water storage. ANOVA revealed one significant interaction between “time” and “dentin treatment” factors, as ER strategy was associated with bond strength decreases after 12 months. All resin luting agents (u200, Ult + Sil, and Ult + SBU) presented higher immediate μTBS with ER adhesive strategy. As the groups Ult + Sil, with both ER and SE adhesive strategies, and (Ult + SBU), with ER adhesive strategy, showed higher μTBS values after 12 months. It was concluded that conventional dual resin cement, combined with ER strategy produced better bond strength to dentin when cementing indirect PICN restoration.

Surface treatments for polyetheretherketone (Peek): Effects on the bond strength to a resin cement and on the fatigue performance of a bonded glass-ceramic

ObjectiveTo evaluate the effect of distinct surface treatments on Peek (polyetheretherketone) adhesion to the resin cement and the mechanical fatigue behavior of lithium disilicate adhesively bonded to it. Materials and methodsPeek slices embedded in plastic rings with self-curing acrylic resin were randomized into 4 groups for adhesion testing, considering the following surface treatment factors: Ctrl (just cleaned with 78 % isopropyl alcohol); Grinding (4219F diamond bur - 46 μm grain size); Air abrasion (45 μm aluminum oxide for 10 s); Sulfuric acid (acid etching for 30 s). All slices received a layer of adhesive agent; resin composite cylinder specimens (Ø = 3 mm; h = 3 mm) were produced and bonded onto the Peek slices using a dual resin cement for the shear bond strength tests (n = 20) through the wire-loop technique. Next, disc-shaped specimens of Peek (Ø = 10 mm; thickness: 2 mm) and lithium disilicate (LD) (Ø = 10 mm; thickness: 1 mm) were produced for the fatigue tests (n = 20) and paired. The LD was treated (5 % hydrofluoric acid for 20 s + silane agent) and adhesively bonded (with dual resin cement) onto Peek (treated with the previously mentioned surface treatments). The fatigue tests were performed with a step-stress approach (20 Hz; 10,000 cycles/step; initial load: 100 N; step-size: 50 N). Roughness, contact angle, topography and fractographic analysis were performed. The adhesive data was analyzed by one-way ANOVA and Tukey post-hoc tests, while the fatigue data were subjected to survival analysis (Kaplan Meier and Mantel-cox post hoc tests). ResultsOnly the air abrasion surface treatment was able to improve the bond strength between Peek and resin cement (p < 0.05); the Grinding and Sulfuric acid groups were similar to the Ctrl. All surface treatments promoted similar fatigue performance. ConclusionAir abrasion promoted increased bond strength between Peek and resin cement, having no detrimental effect on fatigue behavior. Overall, the mechanical behavior under fatigue of a lithium disilicate glass-ceramic was not influenced by the Peek substrate surface treatments.

KNOWLEDGE OF DENTAL SURGEONS IN THE SELECTION AND CEMENTATION OF FIBERGLASS POSTS

The aim of this study is to record the knowledge of dentists in relation to the selection and cementation technique of the fiberglass post in the daily routine of dental professionals to check which fiberglass post brand and anatomy are most used; to describe the reasons that lead the professionals to choose this technique, as well as analyze the types of cement available and the one most used by dentists in cementing the fiberglass post. In addition to helping dental students with information on the topic, taking into account the fact that this type of retainer is a great choice for the reconstruction of endodontically treated teeth, as it is a cost-effective material, it is resistant to chewing forces, aesthetic and simple technique. To carry out the research, an electronic questionnaire was applied, with objective questions for dental students from Faculdade Patos de Minas (FPM), via a Google Forms form, aiming to acquire data on how the dentists use the fiberglass post. Given the results obtained, among the materials used for cementing the post, there was a great preference for dual resin cement, as it has a good adhesion and resistance, however, it has an unsatisfactory polymerization. Furthermore, it was observed that the self-adhesive resin cement launched on the market recently has been highly praised for presenting several advantages. It is concluded that dual resin cement is the most used by dentists in dental offices today, but self-adhesive cement has been the best choice, as it presents properties similar to previous cements and resistance equivalent to conventional cements according to the literature researched.

Fracture load and failure mode of semi-direct resin composite occlusal veneers: Influence of design and mechanical cycling

AimsTo evaluate the influence of the type of preparation and mechanical cycling on the fracture load and failure mode of semi-direct posterior resin composite restorations. MethodsIn total, 70 healthy third molars were used; 10 belonging to the control group (C - unprepared teeth) and 60 teeth prepared and restored with nanoparticle resin composite, divided into 3 groups (n = 20): O - exclusively occlusal preparation (Table Top); OV - occlusal preparation with buccal extension (Veneerlay); OVP - Occlusal preparation with chamfer on the proximal and buccal-lingual/palatal surfaces (Overlay). The preparations were performed with diamond burs with a thickness of 1 mm. The restorations were made with nanoparticulate resin composite (Filtek Z350 XT) and subsequently received additional polymerization (thermoprocessing). Cementation was performed with the use of universal adhesive system (Single Bond Universal) on dental substrate and dual resin cement (RelyX ARC). Half of the teeth in each group (n = 10) were submitted to mechanical cycling, simulating 6 months of clinical service (5 × 105 fatigue cycles), under dynamic loading of 130 N, at a frequency of 2Hz. Fracture load tests were performed in a universal testing machine with a 200 kgf load cell. Failure mode was classified using scores. Generalized linear models and Fisher Exact tests were applied to the data (significance level of 5%). ResultsThere were no significant differences between the types of preparation (p = 0.9435), or relative to cycling (p = 0.3764). The Fisher Exact Test showed a significant association between the groups and the type of failure (p = 0.0006), with preparations O (with cycling) and OVP (with and without cycling) exhibiting most failures with restoration fractures without involvement of the dental remnant. ConclusionsSemi-direct restorations showed resistance to fracture load similar to that of healthy teeth and were capable of withstanding functional masticatory loads. The type of preparation influenced the failure mode of teeth. The Table Top and Overlay types of preparations were those had fewer catastrophic failures, suggesting that since they are more conservative preparations, they made it possible for the tooth to receive a new restorative procedure in the future in cases of failures.

Effect of sodium/calcium hypochlorite on adhesion and adaptation of fiber posts luted with a dual resin cement.

This study aimed to evaluate the effect of different concentrations of sodium hypochlorite (NaOCl) and calcium hypochlorite [Ca(OCl)2] on the bond strength and adaptation of glass fiber posts luted with a dual-curing resin cement. Fifty decoronated premolars were sectioned 14 mm from the apex and endodontically treated. The root canal filling was partially removed. The specimens were divided into 5 groups (n=10) according to the irrigant for post space irrigation: 0.9% sodium chloride (NaCl), (control); 2.5% NaOCl; 5.25% NaOCl; 2.5% Ca(OCl)2; and 5.25% Ca(OCl)2. For each group, irrigation was performed with 5 ml of solution. Afterward, the posts were luted with a dual-curing resin cement. One slice from each third was obtained and submitted to the push-out test and failure modes analysis. An additional slice from the middle third was submitted to confocal images for analysis of adaptation failures (gaps). Two-way ANOVA, Tukey's post-hoc, Kruskal-Wallis with Bonferroni adjusted, and chi-square tests, analyzed data. The group treated with 5.25% NaOCl showed lower bond strength values and generated more cohesive failures compared to the control (p < 0.05). Bond strength decreased from coronal to apical in the post space (p < 0.001). The groups treated with NaOCl had the highest percentages of gaps compared to the control (p < 0.05). Regardless of concentration, Ca(OCl)2 did not influence the bond strength and the occurrence of gaps (P > 0.05). Ca(OCl)2 is a good option for irrigating the post space before luting a fiber post with a dual-curing resin cement.

Efectos del uso de diferentes selladores de conductos radiculares y protocolos para limpiar la dentina intrarradicular sobre la fuerza de unión de una resina compuesta utilizada para reforzar raíces debilitadas

Background: This study evaluated the effects of using different root canal sealers and protocols for cleaning intraradicular dentin on the bond strength of a composite resin used to reinforce weakened roots. Material and Methods: Sixty-four roots of extracted human maxillary canines were weakened, prepared and filled with two different endodontic sealers (Endofill and AH Plus). In half of the sample, set aside for each respective sealer, excess filling material was cleaned. In the other half, the weakened areas were not cleaned, and the excess of sealer was spread on the intraradicular dentin. Intentionally worn areas inside each root were restored with a microhybrid light-cure composite resin (Z100) to reinforce them, with and without acid etching. Prefabricated metal posts were fixed with a dual resin cement (RelyX ARC), and the specimens were submitted to a pull-out test. Statistical analysis was performed by means of Shapiro-Wilk, analysis of variance (one-way ANOVA) and Tukey-Kramer tests (pandlt;0.05). Results: The groups filled with Endofill (GI, GII, GIII, GIV) had the lowest bond strength values, which were similar among each other (pandgt;0.05).The greatest bond strength values were observed in roots filled with AH Plus (GV, GVI, GVII, GVIII), mainly without cleaning of the weakened areas, and followed by acid etching (GVII), and also with cleaning of the weakened areas, however, with no acid etching (GVI) (pandlt;0.05). Conclusion: The greatest bond strength values were observed in roots filled with AH Plus; (1) without cleaning of the weakened areas and with acid etching, and; (2) with cleaning of the weakened areas, but without acid etching.

Y-TZP Physicochemical Properties Conditioned with ZrO2 and SiO2 Nanofilms and Bond Strength to Dual Resin Cement.

Commercial Yttria-tetragonal zirconia polycrystalline (Y-TZP) was subjected to surface treatments, and the bond strength of dual resin cement to Y-TZP and failure modes were evaluated. Disks (12 mm × 2 mm), cylinders (7 mm × 3.3 mm), and bars (25 mm × 5 mm × 2 mm) were milled from Y-TZP CAD-CAM blocks, divided into seven groups, and subjected to different surface treatments; silicatization was used as control. On the basis of the literature, this study evaluated modifications with films containing SiO2 nanoparticles and silane; SiO2+ZrO2-SiO2 (50%) and ZrO2 (50%) nanoparticles, SiO2+ZrO2/Silane-SiO2 (50%) and ZrO2 (50%) nanoparticles, and silane. Specimens were analyzed by wettability (n = 3), surface free energy (n = 3), X-ray diffraction (n = 1), Fourier transform infrared spectroscopy (FTIR) (n = 1), roughness (n = 5), shear bond test (n = 10), and dynamic modulus (n = 3). Specimens treated with hydrofluoric acid-HF 40% presented significantly higher contact angle and lowest surface free energy (p &lt; 0.05). The SiO2/Silane presented crystalline SiO2 on the surface. The surface roughness was significantly higher for groups treated with nanofilms (p &lt; 0.05). Shear bond strength was significantly higher for silicatization, HF 40%/silicatization, SiO2/Silane, and SiO2+ZrO2/Silane groups. The proposed treatments with nanofilms had potentially good results without prejudice to the physicochemical characteristics of zirconia. Generally, groups that underwent silica surface deposition and silanization had better bond strength (p &lt; 0.005).

Evaluation of Antimicrobial Effectiveness of Dental Cement Materials on Growth of Different Bacterial Strains.

BACKGROUND The aim of this study was to evaluate the antimicrobial effectiveness of dental cement materials for the prevention of bacterial growth, which can cause failure of fixed cementation. MATERIAL AND METHODS We developed an agar diffusion disk test in-house to evaluate the antibacterial properties of 3 commercially available dental cement materials (Ketac, Harvard FLB, and Panavia SA Universal Dual Resin cements) compared with a negative control. The materials were tested for the inhibition against Streptococcus mutans (ATCC 10449), Streptoccocus salivarius (ATCC 25975), Enterococcus faecalis (ATCC 29212), and Lactobacilus acidophilus (ATCC 4356). The antimicrobial effectiveness of materials was expressed as the diameters of the inhibition zones around the disk. RESULTS Overall, 240 specimens were tested. All cement materials showed antimicrobial effectiveness. Different microbial strains reacted differently to the different dental cements (all P.

Influence of restorative materials on occlusal and internal adaptation of CAD-CAM inlays

Aim: To evaluate the occlusal and internal marginal adaptation of inlay restorations made of different materials, using CAD-CAM. Methods: Preparations were made for MOD inlays of one-third intercuspal width and 4 mm depth in 30 third human molars. The teeth were restored using CAD-CAM materials (n=10) of nanoceramic resin (Lava Ultimate), polymer-infiltrated ceramic network (VITA ENAMIC), or lithium disilicate glass-ceramic (IPS e.max CAD). The specimens were cemented with dual resin cement and sectioned at the center of the restoration, after which the two halves were evaluated, and photographed The occlusal and internal discrepancy (μm) was determined at five points: cavosurface angle of the occlusal-facial wall (CA-O); center of the facial wall (FW); faciopulpal angle (FPA); center of the pulpal wall (PW); and center of the lingual wall (LW). The data were submitted to the Kruskal-Wallis and the Dunn tests (α=0.05). Results: No difference was observed among the materials regarding the occlusal discrepancy at the CA-O, FPA, or PW internal points. The e.max CAD measurement at FW showed larger internal discrepancy than that of Lava (p=0.02). The internal discrepancy at LW was greater for e.max CAD than VITA ENAMIC (p=0.02). Conclusion: Lithium disilicate glass-ceramic presented greater internal discrepancy in relation to the surrounding walls of the inlay preparations.

Fracture resistance to fixed partial denture abutments with direct and indirect posts

The objective of this study was to evaluate the resistance to fracture of three-element fixed partial dentof glasstment teeth restored with glass fiber posts (GFP) and cast post-and-core (CPC) retainers. Herein, 60 bovine mandibular incisors were divided into two groups (n = 30) according to the retainer type in: 1) resin composite core reinforced with GFP; and II) CPC (Cu-Al). Each pair of roots consisted of one sample, simulating a three-element fixed partial denture. The structures of the fixed three-element partial dentures were made in Ni-Cr alloy. A conventional dual resin cement (RelyX ARC - 3M Espe, USA) was used for all cementation procedures. Samples were subjected to a compressive load onto an orifice at occlusal contact region of the pontic until collapse or fracture. Normal data distribution was verified by D'Agostino &amp; Pearson normality test. Unpaired t test was used for data analysis (α = 5%). The results showed that the the three-element fixed partial denture abutment teeth restored with composite resin cores retained by GFP presented higher fracture resistance compared to the ones restored with CPC (p=0.0009). In conclusion, the resistance to fracture of three-element fixed partial denture restored with resin composite core reinforced with glass fiber posts was higher to the one restored with post-and-core retainers.

"Comparison of Two Types of Dual Resin Cements in Cantilever Dental Bridge Compressive Stress Distribution: Finite Element Analysis"

"Comparison of Two Types of Dual Resin Cements in Cantilever Dental Bridge Compressive Stress Distribution: Finite Element Analysis"

Stress distribution in restorations with glass fiber and polyetheretherketone intraradicular posts: An in silico analysis.

This study evaluated stresses generated at maxillary central incisor (21) root restored with lithium disilicate crown (LDC), and glass fiber (GFP) or polyetheretherketone (PEEK) post. 3D models created by computed tomographic image (i-CAT Cone Beam 3D Dental Imaging System) reproduced maxillary central incisor. Each model had prosthetic LDCs (2.0 mm thick) cemented to GFP or PEEK posts with dual resin cement. Different loads were applied to each model (cervical, incisal, axial, middle). At maximum principal stress, PEEK showed higher stress than GFP in all loads, but with qualitative similarity. At minimum principal stress, PEEK and GFP showed qualitative and quantitative similarities, except axial load. Maxillary central incisor restored with GFP or PEEK and LDC presented, in general, similar stress intensity and distribution for main occlusal loads. Only two of sixteen occlusal loads tested (cervical for maximum principal; axial for minimum principal) showed significant quantitative difference.

Intraradicular fiberglass posts: comparison among different techniques for restoring flared roots

This in vitro study aimed to analyze the fracture strength and failure pattern of flared bovine roots restored with different intraradicular fiber posts and core materials, without a ferrule. To conduct this study fifty bovine incisor roots were treated endodontically, and divided into five groups (n=10), according to the following fiber post techniques and core materials: prefabricated fiberglass post and full-body bulk-fill resin composite (PF-BF); prefabricated fiberglass post and dual function resin cement (PF-RC); direct anatomic post and full-body bulk-fill resin composite (AP-BF); CAD-CAM integrated fiberglass post-and-core (CAD-PC); and adjustable fiberglass post and full-body bulk-fill resin composite (AD-BF). Intraradicular fiber posts were cemented with dual functional resin cement (Allcem Core, FGM), restored with CAD-CAM composite crowns (Brava, FGM), and subjected to loading. The data were analyzed by generalized linear models (p &lt;0.05). It was revealed that AP-BF presented lower fracture strength values compared with PF-RC (p=0.006) and AD-BF (p=0.013). Fractures involving the apical third only in CAD-PC. PF-RC presented only failure patterns involving the core restoration or were limited to the cervical third. PF-RC and AD-BF presented higher failure patterns limited to the core restoration, compared with other groups (60% and 50% respectively). Fractures involving the middle third were observed in the PF-BF, AP-BF, CAD-PC, and AD-BF groups. In conclusion, most of the intraradicular fiber post techniques used, and different core materials presented similar fracture strength values. CAD-CAM integrated fiberglass post-and-core presented more fractures involving the middle and apical thirds than the other groups.

Effect of mechanical cleaning protocols in the fiber post space on the adhesive interface between universal adhesive and root dentin.

The aim of this study was to evaluate the effects of cleaning protocols on the presence of residues, open dentinal tubules, and bond strength of a self-etch adhesive plus a dual-cure resin cement to dentin in the fiber-post space. The methods for cleaning utilized were conventional irrigation (CI), rotary brush with continuous rotary movement (RB), and continuous ultrasonic irrigation (CUI). Sixty bovine incisors were used for fiber-post space preparation. Thirty roots were divided into three groups (n=10) according to the cleaning protocols and submitted to scanning electron microscope to evaluate presence of residues and relative quantity of open dentinal tubules on dentin surface. Similar protocols were performed in the other thirty roots (n=10) using a self-etching adhesive system (Scotchbond Universal) and a dual-cure resin cement (Relyx Unicem 2). After 6months cervical, middle, and apical thirds sections of fiber-post space were submitted to push-out testing. To data ANOVA and Tukey's test were employed (α=5%). RB and CUI showed the lowest presence of residues on dentin surface (p=.015) and the highest bond strength values (p < .001), regardless of the dentin third. CUI presented the highest quantity of open dentinal tubules in middle and apical thirds (p < .001). CI presented the lowest bond strength value of resin cement, regardless of dentin third (p < .001). Mechanical cleaning protocols, such as RB and CUI, presented better surface cleaning capabilities and higher bond strength than CI with dual-cure resin cement employed. The use of a mechanical cleaning protocol seems to cause appropriate condition on the root dentin surface. Mechanical cleaning of root dentin provided greater bond strength of the self-etching system with dual resin cement. Conventional irrigation did not provide adequate root dentin cleaning. RESEARCH HIGHLIGHTS: • The use of a mechanical cleaning protocol seems to cause appropriate condition on the root dentin surface. • Mechanical cleaning of root dentin provided greater bond strength of the self-etching system with dual resin cement. • Conventional irrigation did not provide adequate root dentin cleaning.

COMPARATIVE EVALUATION OF THE SHEAR BOND STRENGTH OF TWO RESIN CEMENTS WITH THAT OF ZIRCON-BASED CROWNS – AN IN-VITRO STUDY

Introduction: Because of ceramics' exceptional esthetical qualities, the range of materials for implicitly rebuilding missing tooth structures has already grown substantially in recent years. One of the earliest ceramics, silica-based ceramics, needs an adhesive attachment to the tooth structures to keep them from breaking. Previous studies looked at the relationship between the properties of human dentine and the shear bond strength of adhesive on a polished, flat tooth structure surface. For the cementation of inlays, Onlays, crowns, posts, and veneers, resin-based adhesive luting substances are often utilized. the self-adhesive qualities are based on phosphoric-acid methacrylates, which demineralize and penetrate the tooth substrate to provide micromechanical retention.&#x0D; Methodology: This study was undertaken to investigate the shear bond strength between zirconia and two resin-luting types of cement. One is a conventionally used dual-cure resin cement and the other is a new universal self-adhesive self-cure resin cement. Methods: The two self-adhesive self-cured resin cement utilized in the current study, Panavia-F 2.0 and Rely X U 100 were two of these relatively novel products.&#x0D; Result: The number of adhesive and cohesive fractures was calculated for both groups .chi-square test was applied to compare the two parameters in both groups. it was found that 60% of Group RelyX–U100 showed cohesive fractures and 13.33% of group Panavia–F2.0 showed cohesive fractures. There was a highly significant difference found in the type of fractures shown by each group.&#x0D; Conclusion: It is thus concluded from the above study that to bond the zirconia restorations to dentin a better shear bond strength can be observed with respect to self-adhesive self-cure cement rather than the conventional dual resin cement where the application of primer &amp; etchants is required for the bonding process.