Self-etching Primer Research Articles

Evaluation of the bonding ability of a nano-structured adhesive system

The most significant advantage of self-etching primers is to simplify bonding procedures and reduce technique sensitivity. AimsThe aim of this study is to evaluate the shear bond strength (SBS) of self-etch primers, such as polyhedral oligomeric silsesquioxanes (POSS) and silica filled adhesive systems and to assess the nano-leakage (NL) at the resin–dentin interface with field-emission scanning electron microscope (FE-SEM) before and after aging. MethodsOne light cured nano-hybrid composite resin and two self-etch primer adhesive systems (Nano-bond and AdheSE) have been used. Sixty extracted sound human molars were prepared for SBS: two self-etch primer adhesive systems (Nano-bond and AdheSE) have been used for bonding a light cured nano-hybrid composite resin. The test was performed at a universal testing machine and twelve were prepared for evaluation of NL at the interface with FE-SEM before and after aging. Data were statistically analyzed using multiple ANOVA and post hoc Scheffe test (p<0.05). ResultsNano-bond showed higher significant SBS values compared to AdheSE groups in the testing groups. Mean while a significant reduction in SBS was observed in each of the tested adhesive systems, after aging, where the highest was recorded by the control, followed by the thermal cycling and finally by the thermal cycling and water storage. The representative micrographs revealed more pronounced NL pattern in the specimens of AdheSE groups when compared to those of Nano-bond. ConclusionsWithin the limitation of this laboratory study, the following conclusions could be drawn:1.The incorporation of the POSS molecules in the dentin adhesive improves its bonding strength.2.Chemical formulation of the dental adhesive influences its bonding efficiency.3.Nano-structured adhesive system shows better resistance to nano-leakage.

The evolution of bonding in orthodontics.

In the early days of fixed-appliance orthodontic treatment, brackets were welded to gold or stainless steel bands. Before treatment, the orthodontist had to create enough space around each tooth to accommodate the bands, and then those spaces had to be closed at the end of treatment, when the bands were removed. This was time-consuming for the orthodontist and uncomfortable for the patient. Banded appliances frequently caused gingival trauma when fitted, and decalcification could occur under the band. In the mid-1960s, Dr George Newman, an orthodontist in Orange, New Jersey, and Professor Fujio Miura, chair of the Department of Orthodontics at Tokyo Medical and Dental University in Japan, pioneered the bonding of orthodontic brackets to enamel. Many developments have occurred in the decades that followed, including many new adhesives, sophisticated base designs, new bracket materials, faster or more efficient curing methods, self-etching primers, fluoride-releasing agents, and sealants. The purpose of this article is to review the history of orthodontic bonding, especially the materials used in the bonding process.

Effect of thermocycling with or without 1 year of water storage on retentive strengths of luting cements for zirconia crowns

Statement of problemBond stability between zirconia crowns and luting cement and between cement and dentin is a main concern; however, only limited evidence is available as to its longevity. PurposeThe purpose of this in vitro study was to measure the retentive strengths of 7 self-adhesive cements (RelyX Unicem Aplicap, RelyX Unicem Clicker, RelyX Unicem 2 Automix, iCEM, Maxcem Elite, Bifix SE, SpeedCem), 2 adhesive cements with self-etch primers (Panavia 21, SEcure), 1 glass ionomer cement (Ketac Cem), 1 resin-modified glass ionomer cement (Meron Plus), and 1 zinc phosphate cement for luting zirconia crowns (LAVA) to extracted teeth after thermocycling with or without 1 year of water storage. Material and methodsTwo-hundred-forty extracted human molars (2 treatments; n=10 per cement) were prepared in a standardized manner. All cements were used according to the manufacturers' recommendations. The intaglios of the crowns were treated with airborne-particle abrasion. After thermocycling (×5000, 5°C/55°C) with or without 1 year of water storage, the cemented ceramic crowns were removed by using a Zwick universal testing device. Statistical analyses were done with the Wilcoxon rank sum and the 2-independent-samples Kolmogorov-Smirnov test. ResultsMedian retentive strengths [MPa] for specimens thermocycled only/thermocycled with 1 year of water storage were as follows: Panavia 21: 1.7/2.5, SEcure: 3.0/3.0, RelyX Unicem Aplicap: 3.1/3.4, RelyX Unicem Clicker: 4.1/4.2, RelyX Unicem 2 Automix: 3.8/3.1, iCEM: 2.3/2.7, Maxcem Elite: 3.0/3.2, Bifix SE: 1.7/1.7, SpeedCem: 1.3/1.6, Meron Plus: 3.1/2.7, Ketac Cem: 1.4/1.4, and zinc phosphate cement: 1.1/1.6. Statistically significant differences were found only among specimens thermocycled only or thermocycled with 1-year water storage (P<.001). ConclusionsSignificant differences in retentive strengths were observed among cements after thermocycling only or thermocycling with 1 year of water storage, but not for the effect of the additional 1 year of water storage.

Effects of type I collagen degradation on the durability of three adhesive systems in the early phase of dentin bonding.

ObjectiveThis study was designed to evaluate the effects of type I collagen degradation on the durability of three adhesive systems in the early phase of dentin bonding.MethodsBonded dentin specimens were prepared using three different types of adhesive systems. Micro-tensile bond strength and degradation of collagen were tested before, and after 1 month or 4 months of aging in artificial saliva. The relationship between micro-tensile bond strength and collagen degradation was analyzed by calculating their Pearson’s correlation coefficient.ResultsAging induced time-dependent reduction in micro-tensile bond strengths for all the tested adhesive systems, although such reduction for the single-step self-etching adhesive G-Bond (GB) was not statistically significant. The bond strength of the two-step self-etching primer adhesive system Clearfil SE Bond (SEB) was similar to that of the two-step etch-and-rinse self-priming adhesive system Single Bond 2 (SB), and they were both significantly reduced after one or four months of aging. A negative correlation was found between the degree of collagen degradation and magnitude of micro-tensile bond strength (r = - 0.65, p = 0.003). The Pearson’s correlation coefficient was 0.426, indicating that 42.6% of the aging-induced reduction in bond strength can be explained by the degradation of collagen.ConclusionsIn the early phase of dentin bonding, there was a negative correlation between the degree of collagen degradation and the magnitude of micro-tensile bond strength. The reduction of bond strength was accompanied by the degradation of collagen. These results provide evidence for the causative relationship between the degradation of collagen and the deterioration of dentin-adhesive interface.

Effect of partially demineralized dentin beneath the hybrid layer on dentin–adhesive interface micromechanics

ObjectiveTo investigate the presence of non-infiltrated, partially demineralized dentin (PDD) beneath the hybrid layer for self-etch adhesive systems, and its effect on micromechanical behavior of dentin–adhesive interfaces (DAIs). This in-vitro laboratory and computer simulation study hypothesized that the presence of non-infiltrated PDD beneath the hybrid layer does not influence the mechanical behavior of the DAI of self-etch adhesive systems. MethodsFifteen sound third molars were restored with composite resin using three adhesive systems: Scotchbond Multipurpose (SBMP), Clearfil SE Bond (CSEB) and Adper Promp L-Pop (APLP). The thickness and length of all DAIs were assessed using scanning electron microscopy, and used to generate three-dimensional finite element models. Elastic moduli of the hybrid layer, adhesive layer, intertubular dentin, peritubular dentin and resin tags were acquired using a nano-indenter. Finite element software was used to determine the maximum principal stress. Mixed models analysis of variance was used to verify statistical differences (P<0.05). ResultsElastic moduli and morphology were found to differ between the adhesive systems, as well as the presence and extension of PDD. SignificanceBoth self-etch adhesive systems (APLP and CSEB) had PDD. The DAI stress levels were higher for the one-step self-etch adhesive system (APLP) compared with the etch-and-rinse adhesive system (SBMP) and the self-etch primer system (CSEB).

Evaluation of self-etching primer and erbium-doped yttrium aluminum garnet laser on bracket bond strength: An in-vitro study

Introduction: The purpose of this study was to evaluate and compare the shear bond strength, the adhesive remnant scores and surface characteristics of the teeth prepared for bonding with erbium-doped yttrium aluminum garnet (Er:YAG) hard tissue laser, self-etching primer (SEP) and phosphoric acid etching. Materials and Methods: Seventy-eight human premolars, extracted for orthodontic purposes were randomly divided into three groups, enamel was irradiated with 37% phosphoric acid in Group-1, with SEP in Group-2 and with Er:YAG laser at 1.5-W in Group-3. After surface preparation standard edgewise stainless steel premolar brackets were bonded; one tooth in each group was not bonded and was examined under a scanning electron microscopic. The brackets were debonded 24 h later; shear bond strengths were measured, and adhesive remnant index scores were recorded. Results: Statistically significant differences were found between phosphoric acid etching, SEP, 1.5-W laser irradiation. Adhesive remnant scores were compared with the Chi-square test, and statistically significant differences were found between all groups. Conclusions: The mean shear bond strength obtained with 37% phosphoric acid etching, SEP and Er-YAG laser etching were clinically acceptable. SEP produces a more conservative etch pattern and more shear bond strength than phosphoric acid. More adhesive was left on the SEP treated enamel as compared to enamel treated with acid and laser etching.

Neodymium-doped yttrium aluminum garnet laser × self-etching primer: Association with mineral trioxide aggregate as retrograde root filling

Objective: The purpose of this study was to assess the effects of laser irradiation and self-etching primer on the microleakage of apicoectomized teeth retro filled with mineral trioxide aggregate (MTA). Materials and Methods: A total of 60 bovine teeth were endodontically treated and had the apical 3 mm resected. Root-end cavities were prepared and the specimens were divided into five groups: Group 1 - control group, teeth only retrofiled with MTA; Group 2 - specimens treated with neodymium-doped yttrium aluminum garnet (Nd: YAG) laser on the inner walls of the root-end cavities; Group 3 - specimens treated as Group 2 added with Nd: YAG laser on the surface of the apical resection; Group 4 - teeth treated with self-etching primer on the inner walls of the root-end cavities, and Group 5 - teeth treated as Group 4 and in addition, treated with self-etching primer on the surface of the apical resection. All the specimens were retrofiled with MTA and sealed with varnish. The teeth were immersed in 2% rhodamine B dye for 24 h. After this period, roots were washed, dried and resected. Marginal microleakage at material/root surface interface was evaluated quantitatively through linear measure in mm with the aid of a steromicroscope and calculated by an image program. Results: The mean values obtained were: Group 1 - 2.76 ± 0.60; Group 2 - 2.30 ± 0.84; Group 3 -2.21 ± 0.85; Group 4 - 1.04 ± 0.76, and Group 5 - 0.84 ± 0.40. ANOVA showed a significant difference among the groups ( P < 0.05) and Tukey’s test revealed that Group 1, Group 2 and Group 3 were different from Group 4 and Group 5. Conclusion: It was concluded that groups that used self-etching primer presented significantly lower degrees of marginal microleakage. Teeth treated with Nd: YAG laser presented same results as control group. The area of application did not reduce marginal leakage (for both laser and self-etching primer). Only MTA as a retro filling material was not sufficient to prevent marginal microleakage.

Comparative evaluation of different prophylaxis pastes on shear bond strength of orthodontic brackets bonded with Self Etch Primer: An in-vitro study

Introduction: The aim of the study was to determine the effect of different prophylaxis pastes on shear bond strength of orthodontic brackets bonded with Self-Etch Primer (SEP). Methods: Two hundred human premolars were divided into 4 equal groups. In Group 1 (control), no prophylaxis was done prior to bonding with SEP. In Groups 2-4 different prophylaxis pastes, that is, pumice, nonfluoridated and fluoridated pastes were used respectively. After bonding, the samples were debonded using a universal testing machine at a cross head speed of 0.5 mm/min. Results: The shear bond strength (MPa) for Group 1-4 was 5.99, 7.51, 7.57, and 7.71, respectively. Conclusions: The result shows that the shear bond strength of brackets bonded with SEP without prior prophylaxis produces statistically significant lower bond strength as compared to brackets which were bonded with prior prophylaxis treatments. The shear bond strengths of orthodontic brackets bonded with SEP with prior prophylaxis with various prophylaxis pastes were not statistically different from each other. The use of fluoridated prophylaxis pastes did not adversely affect bond strength of orthodontic brackets bonded with SEP.

Odsetek niepowodzeń utrzymania się zamków ortodontycznych MBT za pomocą samowytrawiającego się primeru lub szklano-jonomeru modyfikowanego żywicą w porównaniu do metody tradycyjnej w badaniu in vivo

Background. Self-etching primer and resin modified glass ionomer has been introduced to counter phosphoric etching disadvantages.Objectives. Evaluation of the bond failure rate of MBT stainless steel brackets bonded with either self etching primer SEP or resin modified glass ionomer RMGI in comparison with conventional methods CM.Material and Methods. 46 patients with complete permanent dentition were involved in this study. A total of 920 Gemini MBT® brackets (3M Unitek, Monrovia, Calif) were bonded using a split-mouth design. For each patient, four adhesives systems were used: self etching primer SEP (Transbond Plus®, 3M, Unitek, USA), resin-modified glass ionomer RMGI (Fuji Ortho® LC, GC Corp, Japan), light cure LC (Transpond XT®, 3M, Unitek, USA) and chemical cure CC (Unite®, 3M, Unitek, USA). All brackets were bonded by the same clinician. Only first-time bracket failures with tooth number and the remnant adhesive on the enamel were recorded through to 12th month of treatment and observation. Significant differences in bracket failure rate with regard to bonding procedure, patient sex, arch site, and tooth type were determined using the chi-square. The adhesive remnant index was used to determine the bond failure interface.Results. The bond failure rates were 7%, 15.7%, 7% and 6.5% for the SEP, RMGI, LC, CC respectively. Significant differences in failure rates were found between the groups. The maximum bond failure sites were at the enameladhesive interface in SEP and RMGI groups.Conclusion. The clinical study showed that Transbond Plus can be used effectively for bonding brackets, whereas using Fuji Ortho LC is not effective in clinical practice.

Influence of erbium, chromium-doped: Yttrium scandium-gallium-garnet laser etching and traditional etching systems on depth of resin penetration in enamel: A confocal laser scanning electron microscope study.

Objective:This study was performed to assess the resin tag length penetration in enamel surface after bonding of brackets to identify which system was most efficient.Methodology:Our study was based on a more robust confocal microscopy for visualizing the resin tags in enamel. Totally, 100 extracted human first and second premolars have been selected for this study and were randomly divided into ten groups of 10 teeth each. In Group 1, the buccal enamel surface was etched with 37% phosphoric acid (3M ESPE), Group 2 with 37% phosphoric (Ultradent). In Groups 5, 6, and 7, erbium, chromium-doped: Yttrium scandium-gallium-garnet (Er, Cr: YSGG) laser (Biolase) was used for etching the using following specifications: Group 5 (1.5 W/20 Hz, 15 s), Group 6 (2 W/10 Hz, 15 s), and Group 7 (2 W/20 Hz, 15 s). In Groups 8, 9, and 10, Er, Cr: YSGG laser (Biolase) using same specifications and additional to this step, conventional etching on the buccal enamel surface was etched with 37% (3M ESPE) after laser etching. In Groups 1, 5, 6, 7, 8, 9, and 10 3M Unitek Transbond XT primer was mixed with Rhodamine B dye (Sigma-Aldrich, Germany) to etched surface and then cured for 20 s. In Group 2, Ultradents bonding agent was mixed with Rhodamine B. In Group 3, 3M Unitek Transbond PLUS, Monrovia, USA, which was mixed with Rhodamine B dye (Sigma-Aldrich, Germany). Group 4, with self-etching primer (Ultradent-Peak SE, USA) was mixed with Rhodamine B dye (Sigma-Aldrich, Germany). Later (3M Unitek, Transbond XT, Monrovia USA) [Figure 1] was used to bond the modified Begg brackets (T. P. Orthodontics) in Groups 1, 3, 5, 6, 7, 8, 9, and 10. In Groups 2, 4 Ultradent-Peak LC Bond was used to bond the modified brackets. After curing brackets were debonded, and enamel depth penetration was assessed using confocal laser scanning microscope.Results:Group J had a mean maximum depth of penetration of 100.876 μm, and Group D was the least having a maximum value of 44.254 μm.Conclusions:Laser alone groups had comparable depths of penetration to that of self-etching groups but much lower than conventional acid etched groups.

Bond strength of composite resin to enamel and dentin prepared with Er,Cr:YSGG laser.

We aimed to examine the effect of various adhesive systems on the bond strength of composite resin to enamel or dentin prepared with erbium, chromium: yttrium scandium gallium garnet (Er,Cr:YSGG) laser. Each laser-cut enamel or dentin surface was treated with a bonding agent (SBB, Group 1); self-etching primer (SBP) and SBB (Group 2 and control); phosphoric-acid (KET), SBP and SBB (Group 3); KET, sodium-hypochlorite (ADG), SBP and SBB (Group 4); all-in-one adhesive (TSB, Group 5); or KET, ADG and TSB (Group 6). The control group was only polished with wet silicon carbide papers. The enamel shear bond strength of Group 5 was significantly lower than that of other groups (p<0.01). The control group showed higher bond strength compared to Groups 1-6 (p<0.05). Preconditioning using phosphoric acid or phosphoric acid followed by sodium hypochlorite increased the bond strength of composite resin to enamel and dentin prepared using an Er,Cr:YSGG laser.

Effect of a self-etching primer and phosphoric acid etching on the bond strength of 4-META/MMA-TBB resin to human enamel.

The purpose of this study was to evaluate the shear bond strength and durability of 4-META/MMA-TBB resin to human enamel. A self-etching primer that contained 4-META (Teeth Primer, TP) and 35-45% or 60-65% concentrations of phosphoric acid (K-Etchant Gel, KE, and Super Bond C&B Red Activator, RA) were used as the surface treatment agents. A methyl methacrylate (MMA)-based self-polymerizing resin (Super-Bond C&B) was used as a luting agent. The shear bond strength was determined both pre and post thermocycling. The results were statistically analyzed with a non-parametric procedure. The post-thermocycling shear bond strength of the TP group was significantly higher than that of other groups, and that of the KE group was significantly higher compared with the RA group. These results demonstrated that 4-META was effective. Furthermore, when the degree of tooth demineralization was compared, surface treatment with less demineralization using TP was the most effective treatment.

Shear Bond Strength Evaluation of Resin Composite Bonded to GIC Using Different Adhesives.

To evaluate the bonding of composite to glass ionomer cement (GIC) using two different bonding systems. The occlusal surface of 30 teeth was flattened and they were divided into three groups. In Group A, composite (Filtek" Z350 XT, 3M ESPE, USA) was bonded to GIC (Fuji II, GC Corporation, Japan) after initial setting of the GIC being employed as a total-etch adhesive(AdperSinglebond 2, 3M ESPE, USA). In Group B and C, self-etch primer(Adper" Easy One, 3M ESPE, USA) was employed to bond composite to GIC before and after initial setting of GIC respectively. Shear bond strength and nature of fracture of specimens was determined. One-way analysis of variance (ANOVA) was used. Group B showed higher bond strength than Group A & Group C (p<0.01). Group C showed the least bond strength. Bond strength of composite to GIC was significantly higher for self-etch primer group employed on unset GIC.

Impact of Dilution and Polymerization on Cytotoxicity of Dentin Adhesives to Human Gingival Fibroblasts: Early Exposure Time.

Background and aims. The aim of this study was to evaluate the effect of dilution and curing methods of an etch-and-rinse adhesive and a self-etching primer from the same manufacturer at early exposure time on cytotoxicity of primary human gingival fibroblasts.Materials and methods. Primary human gingival fibroblasts were exposed to different dilutions of Adper Single Bond (ASB) and Adper Prompt L-Pop (APL) (3M ESPE, USA). They were evaluated in unpolymerized mode for 20 s, 5 min and 24 h and in polymerized mode for 24 h and 48 h. Cytotoxicity was evaluated using three cytotoxic tests (MTT, cell counting and DNA condensation). Data was analyzed by a one-way ANOVA and Post Hoc Tukey HSD test.Results. Cytotoxicity tests revealed that unpolymerized APL was more cytotoxic compared to ASB after 20 s (P<0.05). By increasing the time to 5 min and 24 h, ASB was more cytotoxic than APL with lower dilutions. Polymerized ASB was more toxic than APL.Conclusion. Both adhesives were cytotoxic in different dilutions, times and curing modes. Cytotoxicity of the unpolymerized self-etching primer (APL) was more than etch-and-rinse adhesive (ASB) in 20 s, which is important clinically and dentists should be aware of the harmful effects and try to minimize it by curing and rinsing soon after composite resin insertion. ASB was more cytotoxic at 5 min and 24h.

Shear Bond Strength of Orthodontic Brackets Fixed with Remineralizing Adhesive Systems after Simulating One Year of Orthodontic Treatment.

The objective of this study is to assess, in vitro, the shear bond strength of orthodontic brackets fixed with remineralizing adhesive systems submitted to thermomechanical cycling, simulating one year of orthodontic treatment. Sixty-four bovine incisor teeth were randomly divided into 4 experimental groups (n = 16): XT: Transbond XT, QC: Quick Cure, OL: Ortholite Color, and SEP: Transbond Plus Self-Etching Primer. The samples were submitted to thermomechanical cycling simulating one year of orthodontic treatment. Shear bond strength tests were carried out using a universal testing machine with a load cell of 50 KgF at 0.5 mm/minute. The samples were examined with a stereomicroscope and a scanning electron microscope (SEM) in order to analyze enamel surface and Adhesive Remnant Index (ARI). Kruskal-Wallis and Mann-Whitney (with Bonferroni correction) tests showed a significant difference between the studied groups (p < 0.05). Groups XT, QC, and SEP presented the highest values of adhesive resistance and no statistical differences were found between them. The highest frequency of failures between enamel and adhesive was observed in groups XT, QC, and OL. Quick Cure (QC) remineralizing adhesive system presented average adhesive resistance values similar to conventional (XT) and self-etching (SEP) adhesives, while remineralizing system (OL) provided the lowest values of adhesive resistance.

Shear bond strength and debonding characteristics of metal and ceramic brackets bonded with conventional acid-etch and self-etch primer systems: An in-vivo study.

BackgroundDifferent in-vitro studies have reported various results regarding shear bond strength (SBS) of orthodontic brackets when SEP technique is compared to conventional system. This in-vivo study was designed to compare the effect of conventional acid-etching and self-etching primer adhesive (SEP) systems on SBS and debonding characteristics of metal and ceramic orthodontic brackets.Material and Methods120 intact first maxillary and mandibular premolars of 30 orthodontic patients were selected and bonded with metal and ceramic brackets using conventional acid-etch or self-etch primer system. The bonded brackets were incorporated into the wire during the study period to simulate the real orthodontic treatment condition. The teeth were extracted and debonded after 30 days. The SBS, debonding characteristics and adhesive remnant indices (ARI) were determined in all groups.ResultsThe mean SBS of metal brackets was 10.63±1.42 MPa in conventional and 9.38±1.53 MPa in SEP system, (P=0.004). No statistically significant difference was noted between conventional and SEP systems in ceramic brackets. The frequency of 1, 2 and 3 ARI scores and debonding within the adhesive were the most common among all groups. No statistically significant difference was observed regarding ARI or failure mode of debonded specimens in different brackets or bonding systems.ConclusionsThe SBS of metal brackets bonded using conventional system was significantly higher than SEP system, although the SBS of SEP system was clinically acceptable. No significant difference was found between conventional and SEP systems used with ceramic brackets. Total SBS of metal brackets was significantly higher than ceramic brackets. Due to adequate SBS of SEP system in bonding the metal brackets, it can be used as an alternative for conventional system. Key words:Shear bond strength, Orthodontic brackets, Adhesive remnant index, self-etch.

Effect of Adhesive Pretreatments on Marginal Sealing of Aged Nano-ionomer Restorations.

Background and aims. Nano-ionomer (NI) interacts with tooth structures superficially, and there is a concern about the enamel bonding ability of mild self-etch Ketac primer. This study compared the effect of different adhesive procedures (self-etching and etch-and-rinse approach) on long-term marginal microleakage of nano-filled resin-modified glass-ionomer (NI) cervical restorations.Materials and methods. Class V cavities were prepared on 72 maxillary premolars. The teeth were divided into six groups: G1: No treatment (NC); G2: Ketac primer (K primer); G3: Etchant + Ketac primer (E+K primer); G4: Self-etch adhesive (Bond Force); G5: Etchant + Bond Force (E+Bond Force); G6: Etchant + Adper Single Bond (Etch and rinse adhesive). All the cavities were restored with Ketac N100. The samples were stored in water for 6 months and thermocycled for 2000 cycles. Marginal sealing was assessed using dye penetration technique. Data were analyzed with non-parametric tests (α=0.05).Results. All the adhesive pretreatments resulted in a lower marginal leakage than that of NC (P≤0.01), except for E+Bond Force at the dentin margin. There was no significant difference between K primer and Bond Force. Microleakage differed significantly between K primer pretreatment and E+K primer (P=0.003), E+Bond Force (P=0.002) and etch-and-rinse adhesive (P=0.001) at the enamel margin, but it did not differ at the dentin margin. E+ Bond Force group showed insignificantly lower leakage at the enamel margin and significantly higher leakage at the dentin margin (P=0.02).Conclusion. Etch-and-rinse adhesive and selective enamel etching along with self-etch adhesive/Ketac primer might improve marginal sealing of aged nano-ionomer restoration.

Does self-etching primer safely bond bleached teeth? An in-vitro study

Aim: The purpose of this in-vitro study was to compare the effect of carbamide peroxide, 16% clinex-gel bleaching on shear bond strength using conventional bonding and self-etching primer bonding (SEP) and to find out how far the changes affect the shear bond strengths at clinically significant level on extracted human tooth enamel. Materials and Methods: Eighty freshly extracted human premolar teeth having moderate to severe dental fluorosis as per Dean's criteria were collected and divided into four groups of 20 each. The four groups are: Group I: Acid etching followed by bonding with Transbond XT (white), Group II: Bleaching, acid etching followed by bonding with Transbond XT (pink), Group III: SEP followed by bonding with Transbond XT (white). Group IV. Bleaching, acid-etching, followed by bonding with Transbond XT (pink). Results: There was a statistically significant difference between the four groups on comparing the mean shear bond strength of Group I, II, III, and IV by one-way analysis of variance test. Summary and Conclusion: Bleaching and bonding with SEP after 30 days storage have comparably similar shear bond strength to the unbleached acid etching group.

Bisphenol A release from orthodontic adhesives and its correlation with the degree of conversion

Our objective was to quantitatively assess and compare the bisphenol A (BPA) released from an orthodontic adhesive using a light-emitting diode device (LED) or a halogen light-curing unit (HLC) at 3 tip-to-bracket distances (0, 5, and 10 mm) and varying curing times using high-performance liquid chromatography. BPA release with self-etching and moisture-insensitive primers with light-cured and chemically cured composites was also evaluated. BPA release was correlated to the corresponding degree of conversion. Our sample consisted of 598 stainless steel first premolar brackets. Of these, 520 were used for assessing BPA release and divided into 13 groups of 40 each. In groups I, II, and III, the composite was cured with the LED for 20 seconds at distances of 0, 5, and 10 mm, respectively. Groups IV, V, and VI were cured with the HLC for 40 seconds at the same 3 distances. Groups VII and VIII were cured for 5 and 10 seconds with the LED, and groups IX and X were cured for 10 and 20 seconds with the HLC at 0-mm distance. Groups XI, XII, and XIII consisted of brackets bonded with a self-etching primer and Transbond (3M Unitek, Monrovia, Calif), with a moisture-insensitive primer and Transbond, and with a chemically cured composite. The remaining 78 brackets were also divided into 13 groups and used for assessing the degree of conversion. The LED devices demonstrated significantly less BPA release and greater degrees of conversion (P <0.05). For both units, BPA release increased and the degree of conversion decreased as the tip distance increased and curing time decreased. The chemically cured group showed significantly less BPA release (P <0.05). Among the light-cured composites, those cured according to the manufacturers' recommendations (40 seconds and 0-mm distance for the HLC unit) released less BPA than did the self-etching primer and the moisture-insensitive primer. The degree of conversion was greatest for the chemically cured composite, whereas it was similar for the conventional, self-etching primer, and moisture-insensitive primer groups. However, correlations ranged from strongly negative to weakly positive between BPA release and degree of conversion. Clinicians should consider using LEDs in clinical practice and should keep the light-cure tip as close to the bracket as clinically possible. Curing time should be according to the manufacturer's recommendations. These steps will ensure less BPA release and a greater degree of conversion. Since chemically cured composites had less BPA release and a greater degree of conversion, they can be considered superior to light-cured composites in this aspect.

Effect of long-term storage on nanomechanical and morphological properties of dentin–adhesive interfaces

IntroductionTo evaluate the influence of storage time on the elastic modulus, micromorphology, nanoleakage, and micromechanical behavior of the dentin–adhesive interfaces of five adhesive systems (Scotchbond Multi-Purpose, Clearfil SE Bond, One Up Bond F, Adper Easy One, and Filtek LS Adhesive) after 24h (T0) and 12 months (T1). MethodsFifty teeth were restored and distributed according to each adhesive system (n=10). At least four specimens were obtained from each tooth. One specimen was evaluated under SEM to obtain the micromorphology of dentin–adhesive interface (DAI). Two specimens were used to assess nanoleakage, one tested in T0 and the other in T1. The last specimen was used for nanoindentation, in T0 and T1, to obtain the initial and final mechanical properties of DAI structures. Two non-restored teeth were evaluated under SEM to obtain the dentin morphology. Laboratorial data were used to build 15 finite element models to assess the maximum principal stress in each time of analysis. ResultsStorage resulted in hydrolysis of the dentin–adhesive interfaces for all groups. Silver impregnation increased for all groups after 1 year storage (p<.05), except for Clearfil SE Bond. In general, a decrease in elastic modulus values was observed for all groups from T0 to T1 (p<.05), mainly at the hybrid layer. The FEAs showed higher stress levels at T1 than T0 simulations for all adhesives. ConclusionAt T1, degradation occurred at the dentin–adhesive interface formed by all adhesives, and the intensity of degradation differed depending on the type of adhesive system used. The interface formed by the self-etching primer containing the 10-MDP functional monomer showed the highest stability among the adhesive systems after 12 months of storage.