Self-adhesive Resin Cement Research Articles

Effect of cementation delay on bonding of self-adhesive resin cement to yttria-stabilized tetragonal zirconia polycrystal ceramic treated with nonthermal argon plasma

Statement of problemNonthermal argon plasma (NTAP) has been reported to improve the bond strength of resin cements to yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) ceramics. However, the effect of the inevitable delay before cementation and after treating Y-TZP ceramics with NTAP is unclear. PurposeThe purpose of this in vitro study was to investigate whether delays of 8, 12, and 24 hours between the Y-TZP ceramic treatment with NTAP and the cementation would affect the surface energy and the bond strength of a self-adhesive resin cement to Y-TZP ceramic. Material and methodsSixty plates and 50 blocks of 3Y-TZP ceramic were divided into 2 groups (n=30 and n=25): as-sintered (AS) and airborne-particle abraded with 50-μm Al2O3 (APA). These groups were further divided into 5 subgroups (n=6 and n=5) according to the delay between the NTAP treatment and the measurement of surface energy and microtensile bond strength (μTBS) evaluation: (0, 8, 12, and 24 hours). For both 3Y-TZP surface conditions (AS and APA), a control group without NTAP treatment was used (ASC and APAC). The surface energy (SE) was evaluated with a goniometer and the 3Y-TZP elemental composition with X-ray photoelectron spectroscopy (XPS). For the μTBS test, the 3Y-TZP ceramic blocks were cemented to composite resin blocks with a self-adhesive resin cement. After storage in distilled water at 37 °C for 24 hours, the 3Y-TZP-composite resin blocks were sectioned into beams and submitted to a μTBS test. Data were submitted to 2-way ANOVA and the Tukey HSD test (α=.05). ResultsFor the AS group, NTAP increased the SE irrespective of the delay before measurement: ASC<0 hour=8 hours=12 hours=24 hours (P<.05). For the APA group, except after 12 hours, NTAP also increased the surface energy (P<.05). XPS analysis showed an increase in the oxygen/carbon ratio after NTAP treatment for both groups. For the AS group, NTAP increased the μTBS after 0, 8, and 12 hours (P<.05), whereas for the APA group this occurred only after 8 hours (P<.05). For the AS and APA groups, the highest μTBS was reached after 8 hours (P<.05). ConclusionsTreatment of 3Y-TZP ceramic with NTAP improved the SE and increased the μTBS of self-adhesive resin cement to 3Y-TZP ceramic. These effects were time dependent, with better results at 8 hours after NTAP treatment.

Proliferation of Fibroblast Cells in Periradicular Tissue Following Intentional Replantation of Vertical Root Fractures Using Two Materials

This study aimed to investigate the fibroblast cells proliferation in periradicular tissue using mineral trioxide aggregate (MTA) and self-adhesive resin cement as the adhesive material for vertical root fracture fragments following intentional replantation. This study used 27 male New Zealand rabbits aged 8-12 weeks. The mandibular incisor of each rabbit was extracted, and to simulate vertical fracture, the incisor tooth was sectioned vertically from the cervical to the 2/3 apical. The samples were randomly divided into three groups of nine each. Group 1 (control group), no application of any material. Group 2, the fracture line was sealed using MTA. Group 3, with self-adhesive resin cement. All teeth in all groups were then inserted back (replanted) into the socket of the rabbits. Each group was further divided into three subgroups according to the duration of replantation, namely, group A: week 1, group B: week 2, and group C: week 3. Rabbits were sacrificed according to each duration of replantation for histological preparations. The number of fibroblast cells was evaluated by counting at the three viewpoints under the light-microscope (400× magnification) and Optilab camera; finally, the calculation results were averaged. Data were analyzed using a two-way ANOVA and post hoc LSD test, with a significance level of 95%. Following MTA application in the third week produced the highest number of fibroblast cells (104 + 29.5) compared to other groups. Conversely, the lowest number of fibroblast cells occurred in the control group in the first week of observation (4.33 + 3.5). MTA produced the greatest fibroblast cell proliferation than self-adhesive resin cement, particularly in week 3 of vertical root fractures replantation. As the adhesive material for vertical root fracture fragments, MTA generated greater fibroblast proliferation than self-adhesive resin cement. Therefore, it is recommended to use MTA to attach vertical root fracture fragments.

Comparative Evaluation of Bond Strength of Different Luting Cements for Cementation of Stainless Steel Bands on Primary Molar Crowns (Stainless Steel and Zirconia Crowns): An In Vitro Study.

Aim and backgroundPrimary teeth are the valuable assets of a child. Apart from the obvious function of delivering esthetics, their most important function is space maintenance for the succeeding permanent teeth. At times, due to unavoidable pathological conditions, there is premature loss of primary teeth. Space maintainers can either be banded to the enamel surfaces of healthy adjacent teeth or to the surfaces of full coronal restorations, the most common ones being stainless steel crowns (SSCs) and zirconia crowns (ZCs). Due to esthetic demands, ZCs have started replacing SSCs and therefore, there needs to be data on the banding of space maintainers on ZCs and the bond strengths obtained on cementations. Thus, the present study planned to evaluate and compare the bond strengths obtained by the banding of stainless steel bands (SSBs) over SSCs and ZCs using type I glass ionomer cement (GIC) and self-adhesive resins.Materials and methodsSixty primary right mandibular molars were divided into four groups, group I, with cementation of SSB on SSC with type I GIC; group II, with cementation of SSB on SSC with self-adhesive resin cement; group III, with cementation of SSB on ZC with type I GIC; and group IV, with cementation of SSB on ZC with self-adhesive resin cement.ResultsThe mean bond strength value of GIC as luting cements in group I is 1.13 ± 0.075 MPa. The mean bond strength value of self-adhesive resin as luting cements in group II is 1.70 ± 0.104 MPa. The mean bond strength value of GIC as luting cements in group III is 1.38 ± 0.100 MPa. The mean bond strength value of self-adhesive resin as luting cements in group IV is 2.06 ± 0.119 MPa.ConclusionThe bond strength of self-adhesive resin was higher when SSB was cemented over SSC when compared with the bond strength of GIC when SSB was cemented over ZC.How to cite this articleKalaskar R, Ijalkar R, Kalaskar A, et al. Comparative Evaluation of Bond Strength of Different Luting Cements for Cementation of Stainless Steel Bands on Primary Molar Crowns (Stainless Steel and Zirconia Crowns): An In Vitro Study. Int J Clin Pediatr Dent 2021;14(6):762–767.

Effect of the application of different concentrations of EDTA on the adhesion of fiber posts using self-adhesive cements.

The purpose of this study was to analyze the effect of the application of different concentrations of EDTA on the adhesion of fiber posts to root dentin using self-adhesive resin cements. After endodontic treatment, 78 single roots were randomly divided into six groups (n = 13) according to the combination of the following factors: surface dentin treatment - control (distilled water), 17% EDTA and 24% EDTA; and self-adhesive resin cement - RelyX U200 (RX); and Multilink Speed (ML). After fiber post cementation, six slices were obtained for each root. Ten roots of each group were used for bond strength (BS) and three for microhardness (MH) evaluations. Data obtained from BS and MH tests for each resin cement were subjected to two-way ANOVA (surface treatment vs. root region) and to a post-hoc Tukey's test (α = 0.05). The lowest BS value was observed in the 24% EDTA group for RX cement, whereas the highest values for ML cement were observed for the control group in the middle and apical regions. In the MH test, the lowest value for RX was observed for 24% EDTA in the cervical region, whereas and the highest value for the ML cement was observed in the control group. Regarding both self-adhesive resin cements tested, the application of 24% EDTA was not able to improve the adhesion of fiber posts to root canal.

Effect of post-space irrigation with acid solutions on bond strength and dentin penetrability using a self-adhesive cementation system.

BackgroundThe aim of this study was to evaluate the effects of surface treatments with 1% peracetic acid (PA), solution containing 17% EDTA (SmearClear, Kerr Endodontics), solution containing a combination of 17% EDTA with 2% chlorhexidine (QMix, Dentsply Sirona) on the post-space root dentin compared to 2.5% sodium hypochlorite (NaOCl) on bond strength and resin tags length in dentin. Material and MethodsForty human-canine roots were endodontically treated and the post space was prepared. The specimens were randomised into four groups (n = 10): control – irrigation with 2.5% NaOCl solution, PA – irrigation with 1% PA, SmearClear – irrigation with SmearClear solution, and QMix – irrigation with QMix solution. The fibre posts were cemented using a self-adhesive resin system (Relyx U200, 3M ESPE). After six months, the specimens were cross-sectioned and subjected to push-out and confocal laser microscopy tests. One-way ANOVA and Tukey’s tests were used to analyse the data (α= 0.05). ResultsPA and QMix presented the highest bond strength values compared to the other groups (p< 0.05). There was no significant difference between the resin tags length in dentin by the groups (p = 0.75). ConclusionsIrrigation of the post space with 1% PA and QMix showed a positive clinical impact on the adhesion between the fiber post and root dentin. However, these materials had no influence on resin tags length in dentin by self-adhesive resin cement. Key words:Fiber post, adhesive cementation, self-adhesive resin cement, root dentin, irrigating solutions.

Effect of surface treatment on the dislocation resistance of prefabricated esthetic fiber posts bonded with self-adhesive resin cement: A systematic review and meta-analysis.

Background:This systematic review aimed to determine the presence of any in vitro proof to validate the utilization of surface treatments to advance the bond strength of fiber posts to intraradicular dentin with self-adhesive resin cements.Methodology:Laboratory studies that assessed the push-out or pull-out bond strength of the prefabricated esthetic posts whose surface was treated with either chemical or physical treatment or a combination and bonded using self-adhesive resin cement within root canal model were included for this systematic review. The review began after obtaining the registration number from the International Prospective Register of Systematic Reviews (PROSPERO ID-CRD42020165009). Study reporting was performed following the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines. Relevant articles were identified using a literature database search in Web of Science, Scopus, PubMed, and EBSCO. Besides this, handsearch was also done to ensure complete capture of the articles.Results:Fifteen articles were then selected and included in this study, out of which four were excluded for meta-analysis due to usage of the artificial substrate. It was shown that an additional step of surface treatment of esthetic fiber post did not result in significant improvement in dislocation resistance. Assessment of risk of bias categorized the available research into high risk and medium risk. The results showed heterogeneity.Conclusion:The use of additional steps such as chemical, mechanical, or a combination of post surface treatment does not have any added benefit. However, the results must be interpreted with caution due to methodological shortcomings.

A novel acrylic resin palatal device contaminated with Candida albicans biofilm for denture stomatitis induction in Wistar rats.

Denture stomatitis is the most frequent oral lesion in removable prosthesis wearers, with high recurrence rates and a complex treatment. ObjectiveThis study describes a protocol to obtain and to contaminate a palatal device with Candida albicans biofilm that could be used for an animal model of denture stomatitis.Methodology Acrylic resin devices (N=41) were obtained from impressions of the palates of Wistar rats with individual trays and polyether. The efficacy of microwave irradiation (MW), ultraviolet light (UV), or ultrasonic bath (US) was assessed by colony viability and spectrophotometric analyses (n=5) in order to select the most appropriate method for sterilizing the devices. Then, different devices (n=5) were contaminated with C. albicans and evaluated by CFU/mL determination, scanning electron microscopy, and laser confocal microscopy. Device stabilization was assessed with either autopolymerizing acrylic resins or a self-adhesive resin cement (n=2). The spectrophotometric data were analyzed by one-way ANOVA followed by the Tukey’s HSD post-hoc test (α=0.05).Results MW was the only method capable of sterilizing the devices, and the contamination protocol developed a mature and viable C. albicans biofilm (~1.2 x 106 CFU/mL). The self-adhesive resin cement was the best stabilization material.Conclusions This acrylic resin palatal device was designed to be similar to the clinical situation of contaminated prostheses, with easy manufacturing and handling, effective stabilization, and satisfactory contamination. Thus, the acrylic device can be a valuable tool in the development of denture stomatitis in rats.

Postspace pretreatment with 17% ethylenediamine tetraacetic acid, 7% maleic acid, and 1% phytic acid on bond strength of fiber posts luted with a self-adhesive resin cement

Context:Pretreatment of radicular dentin with chelating agents improves the bond strength of fiber-posts luted with a self-adhesive resin cement.Aims:The aim of this study was to assess the effects of the three chelating agents as final rinse of the postspace on bond strength of fiber posts luted with a self-adhesive resin cement.Settings and Design:This is an in vitro laboratory study.Materials and Methods:Forty-five mandibular premolars were prepared using MTwo rotary system and irrigation was done with 2.5% sodium hypochlorite. Three groups of teeth samples were considered for postspace preparation and irrigated with different solutions: Group 1: 17% ethylenediamine tetraacetic acid (EDTA); Group 2: 7% Maleic acid; Group 3: 1% Phytic acid. This was followed by the luting the posts with RelyX U200. After a week, from each sample, 2 mm thick slices were obtained from each third of the root and subjected to push-out bond strength testing.Statistical Analysis Used:One-way analysis of variance and Bonferroni's Post hoc analysis was used for assessing the results. The statistical significance level was set at P < 0.05.Results:Bond strength values were improved with maleic acid and phytic acid pretreatment with slight or no significant difference between these groups. A final rinse of postspace with EDTA significantly reduced the bond strength.Conclusions:Maleic acid (7%) pretreatment of postspace improved the adhesion of fiber posts luted with a self-adhesive resin cement.

Comparative evaluation of pull-out bond strength of fiber post using different luting cements in endodontically treated teeth: An in-vitro study

Aim: This study was aimed to evaluate and compare the pull-out bond strength of fiber post using glass ionomer cement (GIC), resin-modified glass ionomer cements (RMGIC), self-etch adhesive resin cement, and self-adhesive resin cement in endodontically treated teeth. Materials and Methods: Forty single-rooted teeth with single canal were decoronated, endodontically treated, post space were prepared and divided into four groups (n = 10) based on the cement used for luting the fiber post. Group 1: GIC, Group 2: RMGIC, Group 3: Self etch adhesive resin cement, Group 4: Self-adhesive resin cement. Pull-out test was evaluated for the prepared samples. Statistical analysis was performed using analysis of variance and Tukey's test (P = 0.05). Results: The mean pull-out bond strength of Group 4 was statistically higher than Group 1,2 and 3. Group 1 showed the least bond strength among all the groups. Conclusion: Within the limitation of this study, self-adhesive resin cements provide better bond strength of fiber post to root canal compared to self-etch adhesive resin cement and glass ionomer based cements.

Bonding to zirconia: Effects of translucency and cusp inclinations using an experimental methodology.

Purpose To investigate the effects of translucency and cusp inclination on the micro-shear bond strength (µSBS) of zirconia to self-adhesive resin cement (SARC).Methods Sixty U-shaped zirconia specimens with 1.0 mm thickness consisting of three planes (0°, 20°, and 30°) simulating different cusp inclinations were fabricated from zirconia blocks of high, moderate, and low translucency (n=20). SARC was bonded to the specimen and light-cured for 40 s. The µSBS was tested using a universal testing machine with a cross-head at a speed of 0.5 mm/min and fracture mode was observed using a stereomicroscope (×50). Two-way analysis of variance followed by a post hoc Tukey's honest significant difference test was used for the statistical analyses (α=0.05).Results Varied µSBS values were found in the test groups (7.1-14.9 MPa). Within the zirconia of the same translucency, the µSBS value of the plane 0° specimen was significantly higher than that of the 20° and 30° planes (all p<0.05). Within the zirconia of the same cusp inclination, the µSBS value of highly translucent zirconia was significantly higher than that of moderate and low translucent zirconia (all p<0.05). There was no significant interaction between cusp inclination and translucency (p=0.525). Among the fracture modes, 83.33% were adhesive failure, 11.11% mixed failure, and 5.56% were cohesive failure.Conclusions Translucency and cusp inclination significantly affect the µSBS of zirconia to SARC. The higher the translucency, the greater are the µSBS values; the higher the cusp inclination, the lower are the µSBS values.

Effect of Nd:YAG and Er:YAG laser tooth conditioning on the microleakage of self-adhesive resin cement

Statement of problem Recently, the application of lasers in restorative dentistry has been considered for cavity preparation and surface conditioning of enamel and dentin. However, the beneficial effects of cavity surface conditioning by laser irradiation on microleakage are still controversial. Purpose This study aimed to compare the microleakage of self-etch adhesive resin cement with Nd:YAG and Er:YAG laser tooth surface conditioning to evaluate the capabilities of these lasers as a reliable replacement for etching cavities. Materials and methods Fifty-four class V cavities were prepared on the buccal and lingual surfaces of 27 sound human premolar teeth. The samples were randomly divided into three groups (n = 18): group 1: no conditioning; group 2: conditioned with Er:YAG laser (2940 nm, 10 Hz, 1.2 W); group 3: conditioned with Nd:YAG laser (1064 nm, 1.5 W, 10 Hz). All the cavities were filled with self-adhesive resin cement. After curing and polishing, the samples were immersed in 2% methylene blue solution for 24 h, and after being embedded in acrylic resin, they were sectioned longitudinally and examined under a stereomicroscope. The data were submitted to Kruskal–Wallis and Dunn tests (α = 0.05). Results The lowest microleakage mean rank was observed in the Er:YAG group (19.19), and the highest mean rank was noted in the Nd:YAG group (33.08), with significant differences between the three groups (P-value = .01). Pairwise comparisons demonstrated significant differences between the Er:YAG and Nd:YAG groups (P-value = .004) as well as Er:YAG and no conditioned groups (P-value =.022). Conclusion The irradiation of the Er:YAG laser (2940 nm, 10 Hz, 1.2 W) on cavity surface resulted in less marginal microleakage of self-etch adhesive resin cement restorations compared to Nd:YAG (1064 nm, 1.5 W, 10 Hz) and no conditioning groups.

Bond strength according to the moment of fiber post cutting fixed with self-adhesive cement to the root dentin.

BackgroundThe fiber posts require a cut in the coronal portion to adjust it to the available clinical space. The cutting of posts cemented may generate tension via bur vibrations of drill on the bonding interface, with the possibility of decreasing the bond strength. Thus, this study aimed to evaluate if the moment of cutting the fiber posts has an effect on its bond strength when fixed with self-adhesive resin cement. Material and MethodsThirty-six bovine teeth were randomly divided into three groups after endodontic treatment and post space preparation (n = 12): IAC- the fiber posts were cutting immediately after cementation; ACR - the fiber posts were cutting after coronal reconstruction with resin; Control - the fiber posts were not cut. The fiber posts were cemented with self-adhesive cement (RelyX U200 - 3M ESPE). After 24 h, the teeth were sectioned perpendicularly and the push-out test was performed in a universal testing machine at a speed of 0.5 mm/min, until failure. Data were analyzed using two-way ANOVA and Tukey’s post-hoc test. ResultsThe effect of moment of fiber posts cutting (p = 0.44) and the interaction between the factors moment of post cutting and third root (p = 0.81) had no significant. The root third factor showed a significant effect (p = 0.01). The bond strength in the apical third was significantly lower than in the middle (p = 0.00) and coronal (p = 0.01) thirds. ConclusionsThe moment of post cutting has no effect on the bond strength of fiber posts fixed with self-adhesive cement to the root canal. Key words:Fiber post, self-adhesive resin cement, push-out bond strength, operative dentistry.

Evaluation of surface roughness and push-out bond strength of glass fiber post with and without surface pretreatments: A scanning electron microscopy study

Objective: The aim is to evaluate and compare the surface roughness and push-out bond strength of glass fiber post with and without surface pretreatments using scanning electron microscopy.Materials and Method: A total of 40 extracted human maxillary central incisors selected were decoronated at 15 mm coronally from the root apex. The teeth were subjected to root canal treatment and the postspace preparation was done with Peeso reamers size 1, 2, and 3, leaving a minimum 4 mm apical seal and created a standard postspace of 10 mm. Forty glass fiber posts (Easy Post, Dentsply) were divided into four groups based on surface treatment of the post with 10 in each. Group I: Without Pretreatment (Control Group) (10 Nos), Group II: 9.6% hydrofluoric acid (10 Nos), Group III: Sandblasting with 110 μm aluminum oxide particles (10 Nos), and Group IV: erbium: yttrium-aluminum-garnet (Er: YAG) Laser (10 Nos). The surface roughness analysis with and without pretreatment was performed under Scanning Electron Microscope and measured in Mountains map premium 7.4 software. The posts were luted with Self-adhesive resin cement (RelyX U200) and light cured for 40s. Push-out bond strength was evaluated using the universal testing machine; the values were recorded, tabulated, and statistically analyzed.Results: The push-out bond strength of the post is significantly increased when the postsurface is treated with 9.6% hydrofluoric acid at all three levels.Conclusions: Acid etching of post with 9.6% hydrofluoric acid increased push-out bond strength significantly without changing the structural integrity of the post whereas Er:YAG can be used as alternative to sandblasting.

Effects of Brown and Green Propolis on Bond Strength of Fiberglass Posts to Root Canal Dentin.

The purpose of this study was to evaluate the effect of brown and green propolis on bond strength of the fiberglass posts to root canal dentin, and to compare it with conventional endodontic irrigants. Sixty bovine teeth were selected, decoronated and randomly distributed into six groups (n=10), according to the irrigation solution: 0.9% saline solution (Control); 2% chlorhexidine (CHX); 5% malic acid (MA); 0.5% ethanolic extract of brown propolis (BP); 0.25% ethanolic extract of green propolis (GP); 2.5% sodium hypochlorite (NaOCl). After root canal treatment, fiber posts were cemented into prepared root canals with a self-adhesive resin cement. The roots were cross-sectioned to obtain two discs from each third and submitted to the micro push-out test. Failure patterns were evaluated under optical microscopy. The influence of irrigants agents was analyzed using one-way ANOVA followed by Games-Howell's test (α=0.05). Failure modes were analyzed using Fischer's exact test (α=0.05). There were statistically significant differences among the groups (P<0.05). The control, NaOCl and BP groups showed the highest bond strength with no statistically significant difference between them (P>0.05). Adhesive failure type was the predominant in all groups. Based on this in vitro study, the use of 0.5% brown propolis did not influence the bond strength of fiberglass posts to root canal dentin, while the use of 0.25% green propolis did affect it negatively.

Influence of different cleaning procedures on the shear bond strength of 10-methacryloyloxydecyl dihydrogen phosphate-containing self-adhesive resin cement to saliva contaminated zirconia.

Purpose To evaluate the effect of different cleaning methods on the shear bond strength (SBS) of a 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing self-adhesive resin cement to zirconia after saliva contamination.Methods Sixty zirconia specimens were randomly divided into four groups (n=15) according to treatment surface. Except for the control group, all samples were contaminated with saliva and were then rinsed with water-spray and air-dried. Subsequently, the specimens were either treated with a cleaning paste (CP), with argon plasma (AP), or did not undergo an additional cleaning process (WS). An MDP-containing self-adhesive resin cement was applied onto the ceramic surfaces. Specimens were stored in water (24 hours) followed by thermocycling (5°C to 55°C for 10.000 cycles). SBS tests were performed in a universal testing machine, and the results (MPa ± SD) were statistically analyzed using ANOVA and Bonferroni post-hoc test. Fractured surfaces were examined to identify the failure types using a stereomicroscopy and SEM.Results The surface cleaning treatment (p<0.05) significantly affected the results. The highest SBS values were observed in the control group (12.16 ± 1.22 MPa) and were statistically comparable to values for the CP group (11.38 ± 1.65 MPa). The AP group (9.17 ± 1.06 MPa) showed significantly higher bond strength than the WS group (6.95 ± 1.20 MPa), but it showed significantly lower strength than the control and CP groups.Conclusions The CP application was the most effective method in removing saliva contamination. The AP treatment could not restore the SBS to the same level as uncontaminated specimens.

Immediate and long-term microshear bond strength of resin-based cements to core build-up materials.

BackgroundTo evaluate the microshear bond strength (μ-SBS) between resin-based cements and core build-up materials after water storage. Material and MethodsCylinders (1x1 mm) of conventional dual-cure resin cement (RelyX ARC, 3M ESPE), universal dual-cure resin cement (RelyX Ultimate, 3M ESPE) or self-adhesive resin cement (RelyX U200, 3M ESPE) were adhered to disks (6x2 mm) made with commercial core build-up materials (Bis-Core, Bisco or LuxaCore Z, DMG) or conventional nanocomposite resin (Filtek Z350 XT, 3M ESPE). The specimens (n=10) were submitted to μ-SBS test using a universal testing machine and fracture pattern analysis at 48 hours or after 9 months of water storage. The data were evaluated by three-way ANOVA for repeated measures and Tukey’s test (α=0.05). ResultsAfter 48 hours, regardless of the resin-based cement used, the μ-SBS to the conventional resin composite (Filtek Z350 XT) was greater compared to other materials. However, after 9 months, there was a statistically significant decrease in μ-SBS values between the conventional resin composite and evaluated luting agents. The μ-SBS values of core build-up commercial materials (Bis-Core and LuxaCore Z) did not change over time. Regardless of the composite used and storage time, there was no statistically significant difference between the resin-based cements. After 48 h, the most prevalent failure was mixed for all groups. However, after 9 months, the core build-up materials showed a predominantly mixed fracture pattern whereas the resin composite presented an adhesive pattern. ConclusionsCommercial core build-up materials achieved stable bonding performance with resin-based cements over time. Key words:Composite resins, resin cement, dental restoration failure.

Microleakage of Temporary Crowns with Different Cement gap

Objective: To evaluate the effect of different cement gap on microleakage of PMMA crowns cemented with resin cement. Materials and Methods: Thirty natural human molar teeth were collected, the root of the teeth was sealed with a double layer of varnish for insulation to a level of 1 mm below the preparation margin, and mounted in an acrylic mold. Teeth were prepared through CNC, PMMA crowns fabricated by cad/cam. Samples were divided into 3 subgroups according to the cement gap(CG) (n=10): 25µm (CG25), 50µm (CG50), 100µm (CG100). PMMA crowns cemented with Breeze Self-Adhesive Resin Cement. Samples were thermocycled for 5000 cycles between two water baths at 5°C and 55°C with a dwell time of 20 seconds and 10 seconds of transfer time. Samples were immersed in methylene blue dye solution for 24 hours, then sectioned buccolingually. Dye penetration was assessed using a spectromicroscope, and then a score assessment was done for the microleakage. Results: The CG50 group scored the lowest median microleakage score, followed by CG100, and finally, CG25. The CG25 group; showed a statistically significantly higher median microleakage score than CG50 or CG100 groups. Conclusion: The cement gap has an effect on the microleakage of PMMA crowns cemented with self-adhesive resin cement. Keywords: Cement gap, Microleakage, PMMA, Resin cement

One year clinical evaluation of fracture and marginal integrety of milled biohpp polyetheretherketon (PEEK) versus zirconia veneered single crowns

Aim: To compare the clinical performance of milled PEEK-based single crowns to zirconia veneered single crowns through evaluation of restoration fracture, margin adaptation, and patient satisfaction. Methodology: Twenty-four full coverage crowns were fabricated for posterior teeth. The patients were divided into two groups according to crowns’ material: Group 1(control group) patients received Zr veneered crowns and Group2 (intervention group) patients received Bio HPP crowns. The preparations were standardized with supra-gingival, chamfer finish line for all teeth. The try-in and provisionalization were performed using CAD/CAM (CAM5-S1) machine with software (Exocad). The restorations were veneered according to manufactures instructions. The restoration surfaces were treated according to the manufacture instructions for each material. Self-adhesive resin cement (by BISCO) was used for both groups for crowns cementation. Fracture, margin integrity and biocompatibility (shade and function) were also evaluated during each recall visit using questionnaire to determine patient satisfaction. These measurements were repeated after two, four, six, eight, ten and twelve months respectively. Results: Fisher’s Exact test was used to compare between the two groups; There was no statistically significant difference between the two groups (P-value = 1.000, Effect size = 0.478) for each time period, respectively. Conclusions: Both Zr veneered and Bio HPP crowns revealed successful clinical performance from the clinical performance aspect and patient satisfaction. No significant difference was recorded between the two materials; regarding the clinical performance and patient satisfaction. Therefore, careful checking of the surface of the veneering material one-year post-cementation is recommended. Keywords: fracture resistance, marginal integrity, zirconium veneered crowns, PEEK crowns.

Bond strength efficiency of a high fluoride and calcium release self-adhesive resin cement: A comparative in vitro study

Aim: To clarify the bond strength of Theracem in comparison to other types of adhesive material, in addition to testing the adhesive remnant index (ARI). Material and Methods: A hundred extracted human premolars were collected for orthodontic purposes. Teeth were stored in 1% Chloramine-T trihydrate as bacteriostatic/bactericidal solution for one week; then, they were transmitted into distilled water. The buccal surface of the studied teeth was kept under surveillance and mounted in acrylic block. Siamese metal pre-adjusted premolar brackets were fixed on the buccal surface using three adhesive cements: Bisco ORTHO, GC Fuji ORTHO LC (Light Cure) and Theracem. The teeth were randomly divided into five groups of 20 specimens each. Group 1 (G1) used 37% phosphoric acid gel, Bisco primer, and Bisco adhesive. Group 2 (G2) used GC Fuji ORTHO LC (Light Cure) without etching. Group 3 (G3) used GC Fuji ORTHO LC (Light Cure) with etching. Group 4 (G4) used Theracem without etching. Group 5 (G5) used Theracem with etching. All the tested specimens were kept at 370°C in a distilled water bath for 24 h. Shear bond strength (SBS) was conducted using a universal microcomputer-controlled electronic test machine. Then, specimens’ surfaces were assessed under a stereomicroscope with a 10× magnification to examine the orthodontics adhesive residue’s buccal surface and scored using ARI. Results: The G4 exhibited the lowest mean bond strength value (M = 11.24, SD = 3.52), whereas G3 yielded the highest bond strength value (M = 25.02, SD = 3.41). The variance analysis revealed F = 61.71, indicating a significant difference among the bond strength values (P < .001). Tukey HSD post hoc testing demonstrated a significant difference in bond strength among groups, except G2 with G1 and G3. Kruskal–Wallis test showed statistically significant differences among all groups (P < .001). On comparison, the least adhesives that remained on the tooth surface were in G4 and G5. Conclusion: Theracem bonding system provides many advantages, as there is no need for an acid-etching step, it is easy to manipulate, and it provides a very suitable S.B.S. with no enamel detachment during debonding. Also, scores 0 and 1 in the ARI test lead to a decrease in enamel damage.

THE EFFECT OF FABRICATION TECHNIQUE AND CEMENT TYPE ON THE RETENTION STRENGTH OF IMPLANT SUPPORTED CROWNS

Objectives: The purpose of this study was to compare the retention strength of implant-supported crowns produced by traditional lost-wax, direct metal laser sintering, CAD/CAM technique by using three different luting cements. Materials and Methods: Ninety standard titanium abutments screwed to analogs then mounted in acrylic resin. Samples divided into three main groups according to the manufacturing technique (N=30). Then groups divided into three subgroups based on the cement type used (n=10). The specimens subjected to the pull-out test by using an universal testing machine at a 1 mm/min crosshead speed. The highest pull-out strength values were recorded in Newton and statistical analyzes were performed by using Two-way ANOVA test and multiple comparison test with Bonferroni correction at a significance level of 0.05. Results: The two-way analysis of variance revealed that the fabrication technique and cement type had a significant effect on pull-out strength (p 0.05). The highest pull-out strength was found in the laser sintering group, while the conventional technique had the lowest values. Within the subgroups self-adhesive resin cement had the highest pull-out strength, traditional cement subgroup had the lowest. Conclusions: Fabrication technique and cement type have statistically significant effect on the retention of the implant-supported crowns.