Reduction In Shear Bond Strength Research Articles

Bleaching effect on bonding performance of composite to enamel.

This study aimed to assess the effects of dental bleaching on the immediate shear bond strength (SBS) of composite to enamel. Different bleaching methods and time intervals between bleaching and composite restoration were examined. A total of 45 enamel specimens were divided into three groups (n = 15) based on the applied bleaching protocol: in-office (A), at-home (B), and unbleached control (C). Groups A and B were then subdivided into three time intervals until bonding: 1, 3, and 7 days. The composite was bonded to enamel using self-etch adhesive technique and submitted to SBS testing. The enamel surface and adhesive interface were observed under scanning electron microscope (SEM). The highest average SBS was measured in the control (unbleached) group (31.1 ± 3.4). A significant difference in SBS was found between the control and in-office bleaching (p < .001), as well as between control and at-home bleaching (p = .034), while the difference between in-office and at-home bleaching methods was insignificant. In relation to the waiting period, a significant reduction in SBS (p < .001) was found 1 day post-bleaching. The weakest marginal sealing to enamel under SEM was observed also 1 day after bleaching. Both bleaching methods significantly reduced the SBS of composite to enamel, especially immediately after the bleaching procedure. Reduction in SBS is temporary and 3-day waiting period seems to be sufficient to reverse the adverse effects of bleaching. RESEARCH HIGHLIGHTS: SBS of composite to enamel is significantly reduced by bleaching procedures, especially immediately after bleaching. The reduction in SBS is temporary and reversible by delaying the restoration for a minimum of 3 days.

Shear bond strength of ultraviolet-polymerized resin to 3D-printed denture materials: Effects of post-polymerization, surface treatments, and thermocycling.

The purpose of this study is to compare the shear bond strength of ultraviolet (UV)-polymerized resin to 3D-printed denture materials, both with and without post-polymerization. Moreover, the effects of surface treatment and thermocycling on shear bond strength after post-polymerization were investigated. Cylindrical 3D-printed denture bases and teeth specimens were prepared. The specimens are subjected to two tests. For Test 1, the specimens were bonded without any surface treatment or thermal stress for comparison with and without post-polymerization. In Test 2, specimens underwent five surface treatments: untreated (CON), ethyl acetate (EA), airborne particle abrasion (APA) with 50 μm (50-APA) and 110 μm alumina (110-APA), and tribochemical silica coating (TSC). A UV-polymerized resin was used for bonding. Half of the Test 2 specimens were thermocycled for 10,000 cycles. Shear bond strength was measured and analyzed using Kruskal-Wallis and Steel-Dwass tests (n = 8). In Test 1, post-polymerization significantly reduced shear bond strength of both 3D-printed denture materials (P < 0.05). No notable difference was observed between the denture teeth and the bases (P > 0.05). In Test 2, before thermocycling, the CON and EA groups exhibited low bond strengths, while the 50-APA, 110-APA, and TSC groups exhibited higher bond strengths. Thermocycling did not reduce bond strength in the latter groups, but significantly reduced bond strength in the EA group (P < 0.001). Post-polymerization can significantly reduce the shear bond strength of 3D-printed denture materials. Surface treatments, particularly APA and TSC, maintained bond strength even after thermocycling.

تحليل الخصائص المورفومترية للأحواض النهرية (السفح الجنوبي لجبل بيرات) بين وادي زنتا ونهر الزاب الكبير

Background and Objectives: This in vitro study was performed to assess the shear bond strength (SBS) of three different fixed lingual retainers using two types of different adhesive systems and fracture modes (Adhesive Remnant Index -ARI) of different retainer’s wire-adhesive combination. Materials and methods: one hundred eighty (180) extracted sound human upper premolar teeth were divided into two groups (90 for each group). Then each group subdivided to three subgroups (30 for each subgroup) bonded with three different fixed lingual retainers (Straight-8 strand braided flat soft wire 0.028 x 0.008 inches db UK, 3M Unitek coaxial multi strand 0.0195-inch wire USA and Ultra-Flex Lingual Retainer 0.9 mm x 0.4 mm IOS USA), which were bonded to the lingual surface of the teeth using two types of different adhesive systems (3M™ Transbond™ LR Adhesive USA and HeyTec Flow SE Composite, Heydent Germany). To assess the shear bond strength, the samples were debonded using a Universal testing machine (Instron). For each specimen, the site of failure was examined using a Stereomicroscope. One-way analysis of variance was used for the statistical analysis. Results: There was a high statistically significant difference between the two study groups (p &lt; 0.001). Straight-8 strand braided flat soft wire combined with 3M Transbond LR Adhesive had the strongest shear bond strength (14.0 ± 4.0 MPa) whereas the minimal SBS was noted in Ultra-Flex Lingual Retainer 0.9 mm x 0.4 mm bonded with HeyTec Flow SE Composite (4.5 ± 2.7 MPa). The site of failure in group one was predominantly at the wire composite interface (cohesive failure), while in group two was in enamel/composite interface (adhesive failure). Conclusion: The simplified bonding procedures (self-etching composite) resulted in unfavorable reduction in shear bond strength. There is still support for the traditional multi-step adhesive technique

Formulation and characterization of experimental orthodontic adhesive containing antibacterial dimethacrylate DABCO monomers: An in vitro study

The purpose of the study was to investigate the antibacterial efficacy and mechanical properties of experimental orthodontic adhesives containing newly synthesized antibacterial dimethacrylate monomers with doubly charged 1,4-diazabicyclo[2.2.2]octane (DABCO) group (dication). Experimental orthodontic adhesives were formulated using varying compositions of synthesized antibacterial dimethacrylate monomers containing DABCO dication, C16DC2DMA and BisC11DCDMA, replacing part of the control group, Transbond™XT. The concentrations of monomers tested were 5% C16DC2DMA, 10% C16DC2DMA, 5% BisC11DCDMA, and 10% BisC11DCDMA. The biofilm-inhibition effects of the experimental adhesives against Streptococcus mutans were tested. Brackets were then bonded to extracted human teeth utilizing the experimental adhesives in the bonding protocol. The shear bond strength and modulus of elasticity of the control and experimental groups were tested. The adhesive remnant index scores were recorded. The experimental adhesives containing 5% or 10% BisC11DCDMA and 10% C16DC2DMA showed significantly lower S. mutans colony forming units (CFU) than the control. Both BisC11DCDMA experimental groups displayed similar mechanical properties as compared to the control, although 10% C16DC2DMA showed a reduction in shear bond strength as compared to the control. For all experimental adhesives, the adhesive remnant index scores were not significantly different compared to the control. BisC11DCDMA is a novel antibacterial dimethacrylate monomer that exhibits the significant ability to inhibit bacterial growth while maintaining acceptable mechanical properties. When incorporated into orthodontic adhesives, this monomer may reduce the occurrence of white spot lesions around brackets in orthodontic patients.

Effect of Different Surface Treatment Methods on the Shear Bond Strength of Resin Composite/Zirconia for Intra-oral Repair of Zirconia Restorations.

A durable resin/zirconia bond is essential for successful intra-oral repair of zirconia restorations. The purpose of this study was to evaluate the influence of two mechanical treatments followed by seven chemical treatments on the shear bond strength (SBS) of composite resin to zirconia. In this in vitro study, 280 zirconia blocks (Y-TZP) were either air-abraded or bur roughened and divided into seven experimental groups (n = 20) in terms of primer/resin application: 1) ZPP, Z-Prime Plus; 2) ZPP + GP, Z-Prime Plus followed by G-premio bond; 3) ZPP + ALB, Z-Prime Plus followed by All Bond Universal; 4) ZPP + CLRF, Z-Prime Plus followed by Clearfil SE Bond; 5)GP, G-Premio Bond 6) ALB, All Bond Universal; and 7) CLRF, Clearfil SE Bond. After composite bonding and storage in distilled water (24 hours), half of each group specimen (n = 10) were thermocycled. All specimens were subjected to shear force. Statistical analysis was performed using Kruskal-Wallis and Mann-Whitney test (α = 0.05). Significant reduction in SBS was observed in all groups after thermocycling(p < 0.05), except for the air-abraded ZPP + CLRF (p = 0.143). After aging, air-abraded CLRF exhibited the highest SBS (13.55 ± 7.8 MPa) and bur roughened ZPP showed the lowest SBS (1.16 ± 1.23 MPa). In the aged specimens, there was a significant difference between air abrasion and bur roughening in all groups (p < 0.05). Air-abrasion followed by application of adhesive (with/without prior primer application) is the most efficient technique for repair of veneered zirconia restorations with resin composite.

Shear Bond Strength of Composite Diluted with Composite-Handling Agents on Dentin and Enamel.

This in vitro study aimed to examine the shear bond strength of composite on the dentin and enamel substrates when mixed with different composite-handling agents (CHAs). Eighty extracted molars were embedded into acrylic resin and sectioned sagittally. On the prepared specimens, four groups of resin mixtures were bonded onto the enamel or dentin surfaces—composite only, composite mixed with Composite Wetting Resin (CWR), composite mixed with Brush and Sculpt (BS), and composite mixed with Modeling Resin (MR). All groups were prepared by mixing at a 1:1 ratio by weight. Each specimen was subjected to the shear bond strength test. After the test, adhesive or cohesive failures were examined at the fractured sites. Data were analyzed using one-way and two-way analysis of variance (ANOVA) and the Tukey post hoc test. All composite groups mixed with CHAs displayed a reduced shear bond strength on dentin and enamel substrates compared to composite alone (p < 0.05). The shear bond strength on dentin decreased in the following order: CWR > BS > MR. A similar pattern was observed on enamel, except that there was no statistically significant difference between BS and MR. Statistically significant interactions between resin mixtures and substrates were found (p < 0.001). On the dentin substrate, adhesive failure dominated while adhesive/cohesive failure dominated on the enamel substrate. Conclusions: The shear bonding strength of composite decreases when mixed with CHAs on both dentin and enamel substrates.

Assessment of chemical, ultrasonic, diode laser,\xa0and Er:YAG laser application on debonding of ceramic brackets

BackgroundRisk of enamel damage that often accompanies ceramic brackets debonding raises the demand of finding an optimal method for debonding of them without adverse effects. Different techniques were proposed in an attempt to facilitate their debonding. Comparison of these techniques is crucial. The aim of this study was to evaluate and compare different techniques for debonding of ceramic brackets in terms of shear bond strength and adhesive remnant index.Materials and methodsA total of 100 extracted premolars were randomly allocated into 5 groups. Ceramic brackets were then bonded to teeth using light cure composite resin. Among test groups; group I: served as control, group II: chemical aided debonding via peppermint oil, group III: ultrasonic aided debonding, group IV: diode laser aided debonding, and group V: Er:YAG laser aided debonding. Brackets were shear tested using universal testing machine followed by ARI assessment and evaluation of enamel microstructure was performed using scanning electron microscopy.ResultsA significantly lower shear bond strength was found in ultrasonic, diode, and Er:YAG laser groups. However, no significant difference was found in the chemical group. A significantly higher adhesive remnant index was found solely in Er:YAG laser group with minimal enamel microstructure alterations.ConclusionsEr:YAG laser is a promising tool in debonding ceramic brackets. Ultrasonic and diode laser significantly reduced shear bond strength. Yet, adhesive remnant index in both groups revealed no difference. Chemical aided debonding had little effect and hence, it cannot be recommended without further development.

Optimizing glass-ceramic bonding incorporating new silane technology in an experimental universal adhesive formulation

ObjectiveIncorporating silane-coupling agent into universal adhesives (UAs) to simplify adhesive luting of glass-ceramic restorations appeared ineffective due to silane’s instability in an acidic aqueous solution. This study aimed to evaluate new silane technology added to an experimental UA to be bonded to glass ceramics without separate prior silanization. MethodsCombined silane technology, consisting of 3-(aminopropyl)triethoxysilane (APTES) and γ-methacryloxypropyltriethoxysilane (γMPTES), was incorporated into an experimental UA formulation, being referred to as ADH-XTE (3M Oral Care). Immediate and aged shear bond strength (SBS) of ADH-XTE onto as-milled (‘AM’), tribochemical silica-coated (‘TSC’), HF-etched (‘HF’), and mirror-polished (‘MP’) glass-ceramic CAD/CAM blocks (IPS e.max CAD) with/without separate silanization was measured (n = 10/group). The control adhesives included Scotchbond Universal (‘SBU’) and Scotchbond 1 XT (‘SB1-XT’). The glass-ceramic surface topography and the fractography of the SBS-debonded specimens were observed by SEM. ResultsWithout separate prior silanization, the experimental UA ADH-XTE, containing combined APTES/γMPTES silane technology, significantly outperformed the glass-ceramic bonding efficiency of its silane-containing SBU precursor, while it performed equally effective as SBU applied with prior silanization. Upon aging, significant reduction in SBS was recorded when ADH-XTE was bonded to TSC glass-ceramic surfaces (p < 0.05), while not to HF ones. Notably, the lowest SBS was obtained when the UAs were bonded to AM and MP glass-ceramic surfaces, in particular when applied without separate prior silanization (p < 0.05). SignificanceThe glass-ceramic bonding capacity of the new combined APTES/γMPTES silane-containing UA ADH-XTE surpassed that of its SBU precursor. HF etching remains needed to durably bond to glass-ceramics.

Performance of Different Orthodontic Brackets after Exposure to Dietary Components: An &amp;lt;i&amp;gt;in Vitro&amp;lt;/i&amp;gt; Pilot Study

Introduction: The aim of this study was to determine whether there was a significant difference in shear bond strength between metal and ceramic brackets when exposed to acidic dietary components (beverages) and to observe the chromogenic potential of each in vitro. Methods: Metal and clear orthodontic brackets were placed on extracted maxillary second premolars and exposed to select beverages three times daily for four weeks. Shade was taken using a colorimeter device at seven intervals and the shear bond strength of each bracket was recorded. Results: There was a variable change in tooth shade with respect to the various beverages in which they were submerged. Coffee and Dr. Pepper had the most pronounced change, whereas Red Bull and water produced little to none, respectively. Compared to controls, brackets submerged in coffee had the greatest reduction in shear bond strength, followed by Dr. Pepper, then Red Bull. Overall, clear brackets showed higher shear bond strength than metal brackets. Conclusion: Acidic dietary components have a negative effect on the shear bond strength of orthodontic brackets, and more pigmented beverages have a higher chromogenic staining potential.

Stereomicroscopic Analysis of Microleakage, Evaluation of Shear Bond Strengths and Adhesive Remnants Beneath Orthodontic Brackets under Cyclic Exposure to Commonly Consumed Commercial “Soft” Drinks

Objective: This study aimed to evaluate the effects of Coca-Cola®, Sprite®, and Maaza® on Microleakage, shear bond strength (SBS) and adhesive remnants underneath orthodontic brackets. Materials and Methods: A total of 192 human premolar teeth were used in this study. The sample was divided into four groups: Artificial saliva (control) [Group 1], Coca-Cola [Group 2], Sprite [Group 3] and Maaza [Group 4]. All the samples were stored in artificial saliva and immersed in their respective testing media (except the control group) for 15 minutes 3 times a day, separated by intervals of 8 hours. The immersion cycle was repeated for 15 days. After the immersion cycle, 24 teeth from each group were tested for SBS and adhesive remnant index subsequently. The remaining 24 teeth from each group underwent dyeing with methylene blue and were analyzed stereomicroscopically to evaluate microleakage underneath the brackets. Kolmogorov-Smirnov and Shapiro normality tests were performed and homogeneity of variance was tested with the Levene test. One-way ANOVA and Kruskal-Wallis tests were carried out separately for SBS, ARI and microleakage. Statistical analyses were performed using SPSS 20 for Windows (SPSS Inc., Chicago) software. Results: Coca-Cola showed a significant reduction in SBS and microleakage (p &lt; 0.05) compared to the other groups. ARI did not show any significant differences between any groups (p &gt; 0.05). The mean microleakage scores were higher for the gingival side of the brackets compared to the incisal side. Both Sprite and Maaza showed significant differences compared to artificial saliva, despite the SBS not being statistically significant (p &gt; 0.05). Conclusions: A significant reduction of SBS was observed in Coca-Cola while increased microleakage was seen in all three drinks compared to artificial saliva.

Adverse effect of consumption of carbonated soft drinks on orthodontic treatment - A systematic review.

The complications of soft drink consumption during orthodontic treatment includes degradation of enamel, reduction in the shear bond strength of orthodontic brackets, and also corrosion of orthodontic wires. The main objective of this review is to discuss the adverse effects of carbonated soft drink (CSD) consumption on patients undergoing fixed orthodontic treatment. A search of studies in MEDLINE (via PubMed), the Cochrane library, Web of science, IndMED, EMBASE, Google scholar and limited grey literature on the effects of consumption of CSDs was conducted. All pertinent abstracts were reviewed for inclusion. Full articles were retrieved for abstracts or titles that met the initial inclusion criteria or lacked sufficient detail for immediate exclusion. Out of the 4484 results obtained from search, 16 articles were selected based on title and 6 articles were eliminated after reading the abstracts. 10 articles were selected for systematic review which included 6 invitro studies, 1 animal study, 1 observational study and 2 invivo studies. Of these, six studies evaluated the effects of carbonated drinks on the shear bond strength of brackets on enamel of which two evaluated the microhardness of enamel, two studies evaluated the mechanical and chemical properties of wires, one evaluated tooth movement and one study focussed on white spot lesions. The results from the selected articles showed that with the consumption of carbonated drinks, there was reduced shear bond strength of orthodontic brackets, altered enamel characteristics, alteration of mechanical and physical properties of orthodontic wires and decrease in rate of orthodontic tooth movement. Based on the available evidence, CSD consumption during orthodontic treatment definitely has an effect on orthodontic appliances, enamel and possibly on tooth movement.

Epigallocatechin gallate, in comparison with other pretreatments, improves resin-enamel bonding following bleaching

With the popularity of dental bleaching, the need of immediate restoration following bleaching is increasing urgently. This study aimed to seek methods to improve the bonding strength to enamel of composite resin after bleaching. The best concentration and reaction time of Epigallocatechin gallate (EGCG) regarding bonding strength after bleaching were determined using micro tensile bond strength test (µTBS) to enamel. Bovine Incisors were randomly divided into six groups. Composite resin was built-up after different pretreatments (deionized water, 10% sodium ascorbate, the remineralization fluid, EGCG of the optimal concentration and 75% ethanol) for 1 h after bleaching. µTBS and scanning electron microscopy (SEM) were used to evaluate the effect to immediate bonding strength after bleaching. The mode of failure was determined by a stereo-microscope at 50-fold magnifications. Treatment with 10% EGCG for 30 mins was selected as the best concentration and reaction time. Bleaching led to significantly reduced shear bond strength (p < 0.05). 10% EGCG produced higher µTBS than other groups (p < 0.05). The resin tags after treatments with the four pretreatments were significantly longer and thicker than the control groups under SEM. The application of 10% EGCG could rescue the resin-enamel bond strength after bleaching.

EFFECT OF DIFFERENT DENTIN TREATMENT PROTOCOLS ON SURFACE ROUGHNESS AND COMPOSITE BONDING

Introduction: With advances in technology, other options besides the traditional cavity preparation with diamond and carbide burs have emerged; among them are laser and sono-abrasive systems. Objectives: The aim of this study was to compare in vitro the effect of (Er:YAG) laser with different radiation distances, sono-abrasion and rotary cutting on the surface roughness of dentin and the shear bond strength of resin composite to dentin using self-etching adhesive system. Materials and methods: 50 extracted human molars were randomly divided into 5 groups (n=10) received the following treatments. Group 1: carbide bur, Group 2: diamond bur, Group 3: sono-abrasion, Group 4: contact Er:YAG laser, Group 5: non-contact Er:YAG laser. Average surface roughness (Ra) was determined with a profilometer. Specimens in all groups were treated with self-etching adhesive system and composite build ups were done with Filtek Z-250. Bonding of resin composites to the dentine specimens was tested in shear mode. For morphological analysis; two extra teeth from each group were examined using a scanning electron microscope (SEM). Results:The shear bond strength of composite to the laser irradiated dentine (contact and non-contact) ranged from 6.64 ± 5.24 MPa and 6.29 ± 2.08 MPa respectively, and were significantly lower than the bond strength seen in other groups. However, the surface roughness of the laser irradiated dentine was significantly higher than that of the sono-abraded dentine and bur-cut dentine. SEM revealed that, the dentine surfaces irradiated by laser showed a scaly and rugged appearance and open dentinal tubules without smear layer production. Conclusions: It was concluded that Er:YAG laser treatment reduced shear bond strength of resin composite to dentin in comparison with conventional treatment with high speed rotary and treatment with sono-abrasion. Different Er:YAG laser distance irradiations did not influence the shear bond strength of composite to dentin.

Evaluation of shear bond strength of brackets bonded to fluoride-treated enamel surfaces: An in vitro study

Enamel decalcification is a well-recognized problem associated with orthodontic treatment with fixed multibanded appliances. Several methods have been proposed to minimize the incidence and severity of white spot decalcification around brackets. The present study is concerned with the evaluation of the effect of different topical fluoride gels, applied before and after etching on the shear bond strength of directly bonded orthodontic brackets. The sample consisted of (70) human upper first premolars distributed to (7) groups: group A served as a control; groups B1, C1, andDl received, for (4) minutes prior to etching, a topical application of neutral sodium fluoride gel (1.1%), sodium monofluorophosphate gel (1.2%), and acidulated phosphate fluoride gel (1.23%) respectively. Groups B2, C2, and D2, on the other hand, were treated, for (4) minutes after etching, with topical application of neutral sodium fluoride gel (1.1%), sodium monofluorophosphate fluoride gel (1.2%), and acidulated phosphate fluoride gel (1.23%) respectively. The brackets were loaded under shear to failure using Universal Compression Machine Apparatus. The shear strengths were recorded in Megapascals. The results of the present study showed that the application of fluoride gels for (4) minutes before and after etching did not alter the shear bond strengths of directly bonded orthodontic brackets, when compared with the control group, for all groups except for group D2 in which the topical application of acidulated phosphate fluoride gel for (4) minutes after etching has resulted in a significant reduction in shear bond strength and severity of white spot decalcification around brackets.

Analysing the potential of hydrophilic adhesive systems to optimise orthodontic bracket rebonding

IntroductionBond failure during fixed orthodontic treatment is a frequently occurring problem. As bracket rebonding is associated with reduced shear bond strength, the aim of the present investigation is to analyse the effect of different innovative rebonding systems to identify optimised rebonding protocols for orthodontic patient care.MethodsMetallic brackets were bonded to the frontal enamel surfaces of 240 bovine lower incisors embedded in resin bases. Teeth were randomly divided into two major experimental groups: in group 1 a hydrophilic primer (Assure™ PLUS) was compared to commonly used orthodontic adhesives (Transbond XT™, BrackFix®, Grengloo™) and a zero control. In group 2 different rebonding systems were analysed using a hydrophilic primer (Assure™ PLUS), a methyl methacrylate-consisting primer (Plastic Conditioner) and a conventional adhesive (Transbond XT™). All teeth were tested for shear bond strength according to the DIN-13990 standard, the Adhesive Remnant Index and enamel fracture rate.ResultsThe hydrophilic primer enhanced shear bond strength at first bonding (Assure™ PLUS 20.29 ± 4.95 MPa vs. Transbond XT™ 18.45 ± 2.57 MPa; BrackFix® 17 ± 5.2 MPa; Grengloo™ 19.08 ± 3.19 MPa; Meron 8.7 ± 3.9 MPa) and second bonding (Assure™ PLUS 16.76 ± 3.71 MPa vs. Transbond XT™ 13.06 ± 3.19 MPa). Using Plastic Conditioner did not seem to improve shear bond strength at rebonding (13.57 ± 2.94). When enamel etching was left out, required shear bond strength could not be achieved (Plastic Conditioner + Assure™ PLUS 8.12 ± 3.34 MPa; Plastic Conditioner: 3.7 ± 1.95 MPa). Hydrophilic priming systems showed decreased ARI-scores (second bonding: 2.63) and increased enamel fracture rates (first bonding: 55%; second bonding 21,05%).ConclusionsBased on the present study we found that rebonding strength could be compensated by the use of hydrophilic priming systems. The additional use of a methyl methacrylate-consisting primer does not seem to enhance shear bond strength. No etching approaches resulted in non-sufficient bond strength.

The long-term consequence of salivary contamination at various stages of adhesive application and clinically feasible remedies to decontaminate

ObjectiveTo analyse the bond quality in dentine post-ageing after salivary contamination and decontamination at different stages of dental adhesive application.Materials and methodsA total of 1120 human dentine specimens were randomly allocated to 14 groups for four intervals (n = 20) to be treated with a self-etching (SE) and universal (U) adhesive. The saliva contamination and decontamination were implemented after surface preparation, after primer application (for SE) and after adhesive curing. The decontamination groups were either rinsed and air-dried or rinsed, air-dried and reapplied with adhesive. They were stored (37 °C, distilled water) for four intervals (1 week, 1 month, 3 months and 1 year) and subjected to shear bond strength (SBS) test at a crosshead speed of 0.5 mm/min.ResultOne-way ANOVA with Tukey’s test (α = 0.05) revealed significant reduction in SBS in all the groups in U adhesive compared with the control group at 1 week (p < 0.0001) and in SE when the contamination took place after primer application. However, decontamination improved the SBS in SE but not in U adhesive. The univariate analysis confirmed significant influences (p < 0.0001) seen by treatment procedure ( {eta}_{mathrm{p}}^2 =0.075), type of adhesive ( {eta}_{mathrm{p}}^2 = 0.328), ageing ( {eta}_{mathrm{p}}^2 = 0.13), experimental groups ( {eta}_{mathrm{p}}^2 = 0.518), and the stage of influence ( {eta}_{mathrm{p}}^2 = 0.60).ConclusionSaliva contamination is detrimental after primer application in SE but, decontamination regained the SBS and maintained it over time. In U adhesive, SBS deteriorated over time irrespective of the contamination.Clinical relevanceSalivary contamination showed different influences on SBS at various stages of restoration with contemporary dental adhesives.

Bond strength of CAD-CAM and conventional veneering materials to different frameworks

Statement of problemNew materials and precise manufacturing processes allow for new processes in the veneering and production of fixed dental prostheses. However, data on the bond strength of computer-aided design and computer-aided manufacturing (CAD-CAM) and conventional veneering materials to substrates bonded with different composite resins are lacking. PurposeThe purpose of this in vitro study was to investigate the shear bond strength (SBS) of 2 CAD-CAM, Lava Ultimate (LVU) and VITABLOCS Mark II (VMII), and 3 conventional veneering materials (VM9, VM13, VTI) to 3 different substrates: zirconia (ZIR), cobalt-chromium (CC), and titanium (TIT). Material and methodsSubstrates and veneering cylinders were manufactured and bonded by using 3 different composite resins, RelyX Unicem (RUL), RelyX Ultimate (RXU), and Sinfony (SIN), after various pretreatments (n=18). Half the specimens underwent artificial aging before SBS testing, and failure types were analyzed. Univariate 1-way ANOVA, Kruskal-Wallis, and Mann-Whitney U were computed (α=.05). ResultsCC substrates bonded with RUL showed the highest SBS (P=.007). ZIR substrates bonded with RXU presented higher SBS than TIT substrates (P=.007). ZIR substrates bonded with SIN showed higher SBS than CC substrates (P<.001). SIN veneered groups showed lower SBS than that observed for VM9/13/VTI (P<.001). SIN veneered LVU and VMII substrates presented lower SBS (P<.001). Thermocycling led to a reduction in SBS for most groups (P=.001-.022). SIN veneered substrates and RXU veneered VMII substrates resulted in lower SBS than that seen for VM9/13/VTI and veneered ZIR substrates bonded with SIN or RXU (P<.001). Adhesive failures were most common. ConclusionsWhile RUL is capable of forming a stable bond to CC without pretreatment, ZIR substrates achieve higher SBS after conditioning with an MDP-containing primer when using RXU or SIN than that seen for RUL. Pretreated CAD-CAM–veneered ZIR substrates bonded with SIN or RXU led to similar SBS results to those observed for conventional veneers, while veneering with SIN resulted in lower SBS.

Effect of bleaching with carbamide peroxide on shear bond strength of orthodontic brackets: A meta-analysis of in vitro studies

This study aimed to evaluate the effect of bleaching with carbamide peroxide (CP) according to different doses and intervals between bleaching and bonding on shear bond strength (SBS) of orthodontic brackets. Cochrane Central Register of Controlled Trials, the Cochrane Database of Systematic Reviews, PubMed, and Scopus were searched for articles published up to June 2018. After removing the duplicates, two of the authors screened the titles and abstracts independently. Assessing the eligibility of the selected full texts was also conducted by two of the authors independently. Disagreements were resolved by discussion. Modified version of Cochrane's risk of bias tool was used to assess the quality of studies. Fifteen studies were selected. Overall, bleaching with CP decreased the SBS by around 2MPa (P<0.0001). Using 10% CP decreased the SBS of the immediately bonded brackets by 5.13MPa (P<0.005). This value was 1.67MPa when the bonding procedure was postponed by one day (P<0.0001). Postponing the bonding procedure for longer periods did not cause a statistically significant change in SBS. Using 11-16% CP, the reduction in SBS of the immediately bonded brackets was 8.51MPa (P<0.01). The SBS decreased by 4.12MPa when the bonding procedure was postponed for 20days (P<0.05). According to one study, use of CP with>16% concentration seemed not to affect the SBS. Bleaching with CP decreases the SBS, especially if the bracket bonding is performed shortly after bleaching. However, given the small number of articles interpretation should be made with caution.

Improving shear bond strength of metallic brackets after whitening.

ABSTRACTObjective: To evaluate a protocol for bonding metallic brackets after bleaching with hydrogen peroxide (HP). Methods: 60 extracted maxillary premolar were randomly divided into an unbleached control group and two groups bleached with a solution of 35% hydrogen peroxide prior to bonding. The teeth in one of the treated groups were bonded immediately after bleaching; while the other group was treated with 10% sodium ascorbate immediately after bleaching and before bonding. The teeth in all groups were stored in an artificial saliva solution for 7 days after bonding. The shear bond strength data was measured in megapascals (MPa) and the fail attempts were verified. The significance level was established at p< 0.05. Results: The unbleached group, in which brackets were bonded to untreated enamel, had the highest bond strength values (11.0 ± 5.7MPa) in comparison to the bleached group (7.14 ± 40MPa), in which brackets were bonded to recently bleached enamel. Slightly improved bond strength was observed in the antioxidant group (8.13 ± 5.4MPa), in which the teeth were bleached and then the antioxidant was applied to the teeth before bonding. Unbleached and bleached groups showed statistically significant difference for shear bond strength (p=0.03) and load strength (p=0.03); no significant differences were noted between unbleached and antioxidant groups (p=0.52).Conclusion: The antioxidant treatment applied immediately after bleaching was effective in reversing the reduction in shear bond strength of brackets after tooth bleaching.

Adhesion, Mechanical Properties, and Microstructure of Resin-matrix CAD-CAM Ceramics.

To investigate the effects of 1-year water storage and surface treatments on shear bond strength (SBS) of two composite cements bonded to resin matrix CAD-CAM ceramics (RMCs) and on the mechanical properties of RMCs. Three types of RMCs were tested: 1. polymer-infiltrated hybrid ceramic (PIHC, Enamic, VITA Zahnfabrik); 2. resin nanoceramic (RNC, Lava Ultimate, 3M Oral Care); and 3. flexible hybrid ceramic (FHC, Cerasmart, GC). One indirect laboratory composite (ILC, Epricord, Kuraray Noritake) was used as control. For each material, 60 plates (14 x 7 x 1 mm) were prepared for the SBS test and submitted to three different surface treatments: following manufacturer's instructions, non-thermal atmospheric plasma application (30 s), and plasma + bonding agent. Two composite cements were tested: RelyX Ultimate (3M Oral Care) and Panavia V5 (Kurarary Noritake). Two resin cylinders (1.5 mm diameter x 1.5 mm height) were bonded to each plate (n = 10), with one tested after 24-h storage in distilled water and the other after 1 year of storage in distilled water. Twenty rectangular bars (12 x 2 x 1 mm) of each indirect material were prepared and submitted to the 3-point flexural test after 24-h or 1-year water storage to determine the elastic modulus (EM) and flexural strength (FS) (n = 10). Fractured samples were also examined with SEM and energy dispersive x-ray spectroscopy (EDS). SBS data were analyzed by four-way ANOVA, and EM and FS data by two-way ANOVA, followed by Tukey's post-hoc test (α = 0.05). Groups treated in accordance with manufacturer's instructions exhibited higher SBS than did plasma and plasma + bonding agent groups for all indirect materials, composite cements, and storage periods tested. In general, RelyX Ultimate displayed higher mean SBS than did Panavia V5, except for some groups of ILC where manufacturer's instructions were followed. After 1-year storage in water, all groups exhibited a significant reduction in SBS, except for some groups that following manufacturer's instructions. ILC showed the lowest values of EM and FS. Among the CAD-CAM materials, FHC exhibited the lowest EM and highest FS means, while PIHC possessed the highest EM and lowest FS means for both storage periods. In general, following the respective manufacturer's instructions yielded the best bond strength results. For most materials, 1-year water storage decreased bond strength of composite cements to RMCs, as well as their FS, while increasing their EM. Microstructure and composition influenced the mechanical properties studied.