Dentin Etching Research Articles

Short dentin etching with universal adhesives: effect on bond strength and gingival margin adaptation

BackgroundShort dentin etching, a relatively recent technique, aims to improve resin-dentin bonding by preserving hydroxyapatite crystals within the collagen spaces. This study explores short dentin etching’s potential in mitigating over-etching issues in deep proximal dentin/cementum margins, an aspect not previously investigated. This study evaluates the microtensile bond strength (μTBS) and marginal adaptation of two universal adhesives using different etch-and-rinse strategies (15-second and 3-second etching) and self-etch strategies, both immediate and post-thermal cycling and mechanical loading.MethodsEighty-four molars underwent μTBS testing, categorized by the universal adhesive type (Tetric Uni and Prime&Bond Uni) (n = 42) and adhesive strategy (n = 14) with half tested after 24 h and the rest post aging. Forty-two molars received occluso-mesial preparations with proximal margins in dentin/cementum and were restored accordingly. Scanning electron microscope (SEM) examination of epoxy replicas for the restoration/gingival dentin interfaces was conducted after 24 h and aging. Dentin etching patterns were assessed using SEM. A three-way ANOVA evaluated μTBS data, while a two-way ANOVA and paired sample t-test analyzed marginal adaptation data (significance level is α = 0.05).ResultsAdhesive type, strategy, and aging significantly influenced μTBS. After aging, Tetric Uni subgroups displayed higher bond strength compared to Prime&Bond Uni subgroups. Marginal adaptation was unaffected by adhesive type or strategy, although aging reduced bond strength and adaptation for both adhesives.ConclusionsThe etch-and-rinse protocol yielded higher μTBS results for the HEMA-free isopropanol-based adhesive (Prime&Bond Uni). Marginal integrity was similar for both adhesives. The 3-second and 15-second etching times produced consistent results in all tests and for both adhesives.Clinical significanceThe adhesive protocol for bonding universal adhesives to dentin is contingent on the adhesive composition.

Effects of lactic acid etching on immediate and aged bond strength of resin-dentin bonding interface.

To investigate the effects of lactic acid etching on the immediate and aged bond strength of the resin-dentin bonding interface, the resin-dentin bonding interface was evaluated 24 hours and 6 months later. A total of 42 isolated third molars were randomly divided into 6 experimental groups according to different lactate concentration (35%, 40%, 45%) and acid etching time (30 s, 45 s), with 37% phosphoric acid etching 15 s as a control. In each group, dentin samples were etched under different acidic conditions and bonded with Adper Single Bond 2 (3M ESPE) as directed. The immediate group was immediately stored in deionized water at 37 °C for 24 h, and the aging group was stored in artificial saliva at 37 °C for 6 months. Immediate and aged bond strengths were measured by a micro-tensile tester, and the specimen fracture surface was observed under a microscope. 14 isolated third molars were randomly divided into 7 groups, and each group was etched with acid. Collagen fibers morphology in dentin was examined after gradient dehydration with ethanol by scanning electron microscopy (SEM). Statistically, there was no difference between the resin-dentin immediate bonding strength of 35% lactic acid for 30 s and 37% phosphoric acid for 15 s, but the aged bond strength was greater than that of the phosphoric acid group. According to scanning electron microscope observations, the collagen fiber morphology in 35% and 40% lactate etching dentin 30 s groups was relatively intact compared with other groups. In conclusion, 35% lactic acid etching of dentin 30 s ensures both immediate and aged resin-dentin bond strength.

Water/ethanol and water/acetone proanthocyanidin solutions enhance the mechanical stability and sealing ability of resin-dentin bonds produced by the cross-linked dry bonding technique

ObjectivesTo evaluate the influence of solvents on the mechanical stability and dentin sealing ability of adhesive interfaces produced on dry dentin after collagen biomodification with a proanthocyanidin-rich grape seed extract (GSE). MethodsFlat dentin surfaces (N = 120) were initially divided into 10 groups. After phosphoric acid etching for 15s, the etched dentin was treated with: water (control), 5 % ethanol, 90 % ethanol, 5 % acetone, 90 % acetone, and the same groups added with 5 % GSE. The treatments were kept on the etched dentin for 60s. Then, the teeth of each treatment were further divided into two groups. Thus, after rinsing, the dentin was kept moist (wet bonding) or air-dried for 60 s (dry bonding). A water-free two-step etch-and-rinse adhesive system (Optibond S, Kerr) was applied, and composite blocks were built up. The teeth were tested for bond strength (μTBS) immediately or after 12 months of aging. Considering the μTBS results, additional teeth were prepared for qualitative analysis of nanoleakage (NL; SEM) and hybrid layer permeability (CLSM). The μTBS data were analyzed with three-way RM ANOVA and Tukey (α = 0.05). ResultsThe immediate μTBS did not differ among treatments for wet dentin. For dry dentin, GSE in 5 % ethanol or acetone presented the highest μTBS values, the latter similar to wet control. After 12 months, μTBS of GSE in 5 % ethanol or acetone were comparable to the immediate results for wet and dry techniques. These reduced NL and improved dentin sealing for both dentin wetness conditions like the immediate wet control. ConclusionsThe application of 5 % GSE to etched dentin, either in 5 % ethanol or 5 % acetone, resulted in enhanced mechanical stability and dentin sealing of interfaces produced on dry dentin. SignificanceDentin biomodification with proanthocyanidin in the presence of ethanol or acetone makes bonding procedures less sensitive by eliminating the need to keep dentin wet and increasing the quality and stability of hybrid layers produced on dry etched dentin.

Evaluation of adhesive bond strength of restorative materials to hard tissues of deciduous teeth based on adhesion technique

Relevance. Treating caries in deciduous teeth remains one of the most complex challenges in pediatric dentistry. The bond strength between the enamel and dentin of deciduous teeth and restorative materials is crucial for the durability of hard tissue restorations in these teeth. This article evaluates the adhesive strength of restorative materials to the enamel and dentin of deciduous teeth using a universal adhesive system, both with and without prior etching with orthophosphoric acid.Purpose. To assess the adhesive bond strength of dental filling materials to the hard tissues of deciduous teeth, contingent upon the enamel and dentin etching techniques used with a universal adhesive system.Materials and methods. This study measured the adhesive strength of a composite filling material to the enamel and dentin of deciduous teeth using a universal adhesive system. The methods included both the absence of preliminary etching with 37% orthophosphoric acid (self-etch technique) and the application of preliminary etching of enamel and dentin with 37% orthophosphoric acid (total-etch technique). Sixty extracted deciduous teeth from children aged 6-8 years were used. Adhesive strength was assessed using the shear test of the filling material in cylinder form against the substrate surface.Results. Significant differences were observed in the adhesive bond strength of the composite material to the hard tissues of deciduous teeth when using 37% orthophosphoric acid before applying the adhesive system (total-etch technique) compared to no preliminary etching (self-etch technique). When filling carious lesions in deciduous teeth, if the defect is within the enamel, etching the surface with 37% orthophosphoric acid significantly (by two-fold) enhances the adhesive strength of the bond with the composite material using a universal adhesive. However, when repairing defects located deeper than the enamel layer in deciduous teeth, no statistically significant differences were observed in the adhesive strength with or without dentin etching. The optimal adhesive bond strength of composite materials to the hard tissues of deciduous teeth under laboratory conditions was attained by selectively etching the enamel with 37% orthophosphoric acid, followed by the application of a universal adhesive system to both the enamel and dentin.

Effect of argon plasma and dentin rehydration on bond strength of dental adhesives to etched dentin.

This study investigated the effects of nonthermal atmospheric pressure plasma (NAPP) application and dentin rehydration with water (REHY) on bond strength (BS) of adhesives. Three etch-and-rinse adhesives were tested: Scotchbond Multi-Purpose (SBM / water-based primer + adhesive resin), Gluma Bond Universal (GBU / single-bottle containing acetone as organic solvent) and Prime&Bond Universal (PBU / single-bottle containing propanol as organic solvent). Adhesives were applied: 1- to phosphoric acid-etched dentin (Control), 2- after NAPP application for 45 seconds to etched dentin or 3- after REHY with water (10 seconds) of plasma-treated etched dentin. BS was performed using human molars and microtensile test, in which specimens were tested after 24 hours or one year (n=6). BS data were analyzed by three-way mixed ANOVA and Bonferroni's test (α=0.05). The morphology of etched dentin (n=3) and the dentin-adhesive interfaces (n=3) were evaluated using SEM. NAPP and REHY did not increase the BS of GBU and PBU. The BS of SBM to etched dentin not treated with NAPP (Control) reduced significantly after one year. The PBU adhesive showed the highest bond strength to dentin when the adhesives tested were applied after REHY. Phosphoric acid demineralized dentin to a depth of 5 mm that allowed the adhesive penetration into the dentinal tubules, forming the resin tags. Interfacial structures were maintained after one year. Argon plasma treatment was not beneficial in increasing the dentin bond strength of adhesives to etched-dentin at 24 hours. However, rehydration after plasma application prevented the bond strength reduction for three-step adhesive after one year.

Effects of an MDP-based surface cleaner on dentin structure, morphology and nanomechanical properties

ObjectiveTo analyze the effect of Katana™ Cleaner (KC) in nanomechanical and triboscopic properties of etched dentin. MethodsDentin disks from human third molars were prepared. Two main groups of study were established in function of the etching conditioning, phosphoric acid (PA) and Clearfil SE Bond primer (CSEB). Four subgroups were tested within each group: i) untreated dentin (UD), ii) etched dentin (ED) [(PAED/CSEB)], iii) etched dentin contaminated with saliva (PAED+S)/(CSEB+S), and iv) etched and contaminated dentin treated with KC (PAED+S+KC)/(CSEB+S+KC). Nano-DMA testing and imaging, atomic force microscopy (AFM) analysis and nanoroughness (SRa) measurements were obtained. Field emission scanning electron microscopy (FESEM) images were also acquired. ResultsPhosphoric acid etched dentin samples and those specimens contaminated with saliva (PAED+S) attained the highest SRa values, that decreased after Katana™ Cleaner application (PAED+S+KC). In the group of dentin treated with CSEB primer, all subgroups performed similar, except in CSEB+S that attained the highest SRa values. The treatment with KC restored the original values of complex modulus of the untreated dentin. KC application produced the lowest and the highest tan delta values on PAED and CSEB groups, respectively. ConclusionKatana™ Cleaner provided equally mature dentin surfaces after any of the etching methods. Tan delta increased when Katana™ Cleaner was applied on the dentin surface previously etched and contaminated with saliva, regardless the kind of etchant, thus facilitating the dissipation of energy for elastic recoil during loading. Clinical significanceKatana™ Cleaner application after saliva contamination originated similar low roughness levels, regardless the type of etching method. Both complex and storage moduli were similar, after Katana™ Cleaner application, in any case.

Silver diamine fluoride and resin-dentin bonding: Optimization of application protocols

ObjectiveTo evaluate the effect of SDF-based treatments following delayed bonding and surface treatment approaches on resin-dentin bonding efficiency of a universal adhesive under different application modes. MethodsMid-coronal dentin surfaces from sound third molars were randomly treated with 38% silver diamine fluoride (SDF) and/or additionally with potassium iodide (SDF/KI). Untreated dentin served as control. SDF-treated teeth were assigned to groups according to surface treatment approaches (air-abrasion and water rinsing), the application mode of a mild universal adhesive (etch-and-rinse or self-etch) and delayed bonding (immediate, 7, 15 or 30 days). Microtensile bond strength (n = 5), SEM analyses of hybrid layer formation and dentin etching patterns and dentin permeability were evaluated. Data were analyzed with factorial ANOVA. ResultsSDF-based treatments affected dentin bonding depending on application mode and surface treatment approaches (p<0.001). Etch-and-rinse bonding was not affected by SDF-based treatments (p<0.05), producing more homogenous hybrid layers. While dentin etching patterns of etch-and-rinse application were not affected by SDF-based treatments, self-etching presented limitations. Bond strength reductions of self-etched dentin were restored by silver-removal strategies containing a water-rinsing step (p<0.05). Delayed bonding additionally reduced dentin permeability (p<0.05), further decreasing with longer periods (p<0.05). ConclusionAlthough the negative effect of SDF-based treatments on resin-dentin bonding can be avoided by strategies incorporating water-rinsing before hybridization, delayed bonding brings additional advantages due to higher mineral deposition. Clinical significanceWhile the etch-and-rinse technique avoids major bonding drawbacks to SDF-treated dentin, self-etch bonding requires removal of excess silver deposits before hybridization. Performing SDF-based treatments and dentin hybridization in separate sessions (>15 days apart) potentialize mineral deposition improving caries control and service life of composite restorations.

Enamel and Dentin Etching with Glycolic, Ferulic, and Phosphoric Acids: Demineralization Pattern, Surface Microhardness, and Bond Strength Stability.

This study evaluated the etching pattern, surface microhardness, and bond strength for enamel and dentin submitted to treatment with phosphoric, glycolic, and ferulic acids. Enamel and dentin blocks were treated with phosphoric, glycolic, and ferulic acid to evaluate the surface and adhesive interface by scanning electron microscopy (2000×). Surface microhardness (Knoop) was evaluated before and after etching, and microtensile bond strength was evaluated after application of a two-step adhesive system (Adper Single Bond 2, 3M ESPE) at 24 hours and 12 months storage time points. Analysis of variance (ANOVA) and Tukey's test showed a decrease in the microhardness values for both substrates after application of each acid (p<0.0001). The reduction percentage was significantly higher for enamel treated with phosphoric acid (59.9%) and glycolic acid (65.1%) than for ferulic acid (16.5%) (p<0.0001), and higher for dentin that received phosphoric acid (38.3%) versus glycolic acid (27.8%) and ferulic acid (21.9%) (p<0.0001). Phosphoric and glycolic acids led to homogeneous enamel demineralization, and promoted the opening of dentinal tubules, whereas ferulic acid led to enamel surface demineralization and partially removed the smear layer. The adhesive-enamel interface showed micromechanical embedding of the adhesive in the interprismatic spaces when phosphoric and glycolic acids were applied. Ferulic acid showed no tag formation. Microtensile bond strength at both time points, and for both substrates, was lower with ferulic acid (p=0.0003/E; p=0.0011/D; Kruskal Wallis and Dunn). The bond strength for enamel and dentin decreased when using phosphoric and glycolic acids at the 12-month time evaluation (p<0.05). Glycolic acid showed an etching pattern and microhardness similar to that of phosphoric acid. Ferulic acid was not effective in etching the enamel or dentin, and it did not provide satisfactory bond strength to dental substrates.

Effects of Er: YAG, Er,Cr: YSGG, and Nd: YAG laser irradiation and adhesive systems on the immediate and long-term bond strength of dentin: a systematic review and meta-analysis.

At present, lasers are increasingly used in the oral clinical field, and research and applications in dental hard tissue treatment are also increasing. The effect of laser etching dentin on the bonding strength of composite resin reported in the literature is still inconclusive. The purpose of this review was to evaluate whether laser etching can improve the immediate and long-term bonding strength of dentin and investigate the effect of different types of adhesives on the bonding strength of dentin. Two reviewers performed a literature search up from January 2012 to November 2021 in four databases: MEDLINE (PubMed), Web of Science, EMBASE, and the Cochrane Library. A total of 25 studies were included in the meta-analysis. The Cochrane Collaboration Bias Risk Assessment tool was used to evaluate the quality of the included literature, and an analysis was carried out using Review Manager Software version 5.3. The aging bond strength of dentin after erbium (Er): yttrium aluminum garnet (YAG) laser treatment was significantly lower than that of dentin in the bur group (P < 0.00001). At the same time, the bond strength of dentin immediately and aging after (Er), chromium-doped (Cr): yttrium scandium gallium garnet (YSGG) laser treatment was lower than that of dentin in the bur group (P < 0.05). There was no significant difference in the immediate and aging bonding strength among samples in the Er: YAG laser, Er, Cr: YSGG laser, and blank control groups (no laser or bur). The aging bond strength of samples after neodymium-doped (Nd): YAG laser treatment was higher than that of samples in the blank control group (P < 0.05); in addition, the performance of self-etching adhesive was slightly better than that of acid etching adhesive. Regardless of the applied surface treatment and the adhesive employed, dentin after aging showed significant bond degradation (P < 0.05). There was high heterogeneity of bond strength between different groups, and the small number of studies and the contradictory results may be the main reasons for this outcome.

Effect of phytic acid on dentinal collagen solubilization and its binding and debinding potentials to dentin

ObjectivesTo study phytic acid (IP6) effect on collagen solubilization by assessing hydroxyproline (HYP) release, evaluate its binding to demineralized (DD) and mineralized dentin (MD) and determine the effect of different media on debinding of IP6. MethodsDemineralized dentin beams were incubated in 1%, 2% or 3% IP6 and HYP release was evaluated at 1 or 3 weeks and compared to those obtained in untreated control or phosphoric acid (PA)-treated beams. DD or MD powder was treated with 1%, 2% or 3% IP6 and the decrease in IP6 amount was quantitated by ultraviolet–visible spectroscopy. IP6-treated samples were re-suspended in distilled water, ethanol, urea or sodium chloride and the amount of IP6 displaced was determined. ResultsAt 1 week, the control group and IP6 showed lower HYP release when compared to PA (P < 0.05). There was no difference among PA, IP6 and control at 3 weeks (P = 0.22). IP6 binding was concentration dependent. 1% IP6 had higher binding potential with MD compared to DD while 2% IP6 showed the opposite result (P<0.05). 3% IP6 had similar binding values between DD and MD (P = 0.53). The highest debinding in MD occurred with urea for 2%, 3% and 1% IP6 in descending manner. Within each concentration of IP6 in DD, the highest debinding effect was reported with ethanol. ConclusionsIP6 bound to DD and MD in a concentration-dependent manner. IP6 was debound from DD mostly by the action of ethanol, while in MD, urea caused the most displacement. Collagen solubilization of IP6-treated DD was comparable to untreated DD. Clinical significanceThese findings add to the potential use of IP6 as an alternative to PA for dentin etching which possibly results in long-term stability of resin-dentin adhesion.

Effect of dentin pretreatment with dialdehyde carboxymethyl cellulose on dentin properties and long-term adhesion

ObjectivesThe aim of this in vitro study was to evaluate the effect of pretreatment of dentin with different concentrations (0, 1%, 2.5% or 5%) of dialdehyde carboxymethyl cellulose (DCMC) on the biodegradation rates, mechanical properties of the dentin and long-term dentin bonding (μTBS and nanoleakage). MethodsIn all tests, specimens were designated to 4 groups: Control (without DCMC), DCMC1%, DCMC2.5% and DCMC5%. For the biodegradation evaluation, dentin beams (n = 5) were prepared (2x2x6mm), dehydrated, and demineralized. After, the beams were immersed in test solutions for 24h. After, the biodegradation rate was quantified by hydroxyproline assay. The nano-indentation technique was used to measure nanohardness and elastic modulus. 2 mm thick dentin slices (n = 5) were prepared. After dentin etching, the pretreatment solution (according to groups) was applied for 1 min, followed by drying with absorbent paper. After bonding procedure and restoration, the specimens were polished and the nanohardness and modulus of elasticity were evaluated. For μTBS, the dentin of forty-eight teeth (n = 6) was etched and pretreated for 1 min according to groups, the adhesive system was applied, and resin composite buildups were constructed incrementally. Beams (1 mm2) were obtained and μTBS was evaluated after 24h and 1 year of water storage. 2 beams of each tooth were separated for nanoleakage tests (after 24h and 1 year of water storage). ResultsControl and DCMC1% presented higher biodegradation rates when compared to DCMC2.5% and DCMC5%. The nanohardness of dentin and hybrid layer was higher for DCMC1%, DCMC2.5% and DCMC5% when compared to Control. DCMC2.5 and DCMC5% increased the modulus of elasticity of hybrid layer, when compared to Control and DCMC1%. DCMC1%, DCMC2.5% and DCMC5% showed lower immediate μTBS than Control, but they showed no decrease in μTBS and nanoleakage after 1 year of storage. Control showed significant decrease of μTBS and significant increase of nanoleakage after aging. ConclusionsThe use of DCMC as a dentin pretreatment decreased the biodegradation rate, improved the mechanical properties of dentin, and preserved the long-term bond strength.

Effect of the Viscosity and Application Time of Different Phosphoric Acids on the Bond Strength and Nanoleakage of Fiber Posts to Root Dentin.

To evaluate the effect of application time and viscosity of meta-phosphoric acid (MPA) and ortho-phosphoric acid (OPA) on the push-out resin-dentin bond strength (PBS) and nanoleakage (NL) at the adhesive-root dentin interface. Ninety-six roots of premolars were endodontically prepared and randomly assigned into groups according to the (i) acid (OPA and MPA), (ii) viscosity (gel and liquid), and (iii) application time (7 and 15 seconds). Fiber posts were cemented to the roots, which were then transversally sectioned into serial slices. The slices (cervical, medium, and apical) were subjected to PBS or NL. Analysis of the dentin etching pattern was performed using scanning electron microscopy (SEM). The PBS (MPa) and NL (%) data were subjected to three-way repeated-measures analysis of variance (ANOVA) and Tukey's test (α=0.05). The cross-product interaction was significant for both PBS and NL (p<0.001). No significant difference in the PBS was observed with the use of OPA compared to MPA (p>0.05). Higher PBS values were observed in the groups etched for 15 seconds compared to 7 seconds, regardless of the acid, viscosity, or root third (p<0.05). Lower NL was observed for MPA etching when compared to OPA etching (p<0.05), and these values were not affected by increasing the application time or acid viscosity (p>0.05). A more pronounced etching pattern was observed with OPA than MPA regardless of the acid viscosity. The use of 40% meta-phosphoric acid promoted adequate bond strength without increasing dentin demineralization or void spaces in the hybrid layer.

Noncarious cervical lesions: Morphology and progression, prevalence, etiology, pathophysiology, and clinical guidelines for restoration.

To synthesize the literature regarding noncarious cervical lesions (NCCLs) and propose clinical guidelines when lesion restoration is indicated. A PubMed search was performed related to NCCL morphology, progression, prevalence, etiology, pathophysiology, and restoration. NCCLs form as either rounded (saucerlike) depressions with smooth, featureless surfaces that progress mainly in height or as V-shaped indentations that increase in both height and depth. Prevalence ranges from less than 10% to over 90% and increases with age. Common locations are the facial surfaces of maxillary premolars. They have a multifactorial etiology due to personal habits such as excessive horizontal toothbrushing and consumption of acidic foods and drinks. Occlusal factors have been identified as contributing to the prevalence of NCCLs in some studies, whereas other studies indicate there is no relationship. The concept of abfraction has been proposed whereby mechanical stress from occlusal loading plays a role in the development and progression of NCCLs with publications supporting the concept and others indicating it lacks the required clinical documentation. Regardless of the development mechanism, demineralization occurs and they are one of the most common demineralization diseases in the body. Treatment should be managed conservatively through preventive intervention with restorative treatment delayed until it becomes necessary due to factors such as lesion progression, impact on patient's quality of life, sensitivity, poor esthetics, and food collection may necessitate restoration. Composite resins are commonly used to restore NCCLs although other materials such as glass ionomer and resin-modified glass ionomer are also used. Sclerotic dentin does not etch like normal dentin and therefore it has been recommended to texture the dentin surface with a fine rotary diamond instrument to improve restoration retention. Some clinicians use mechanical retention to increase retention. Beveling of enamel is used to increase the bonding area and retention as well as enhance the esthetic result by gradually creating a color change between the restoration and tooth. Both multistep and single-step adhesives have been used. Dentin etching should be increased to 30 seconds due to the sclerotic dentin with the adhesive agent applied using a light scrubbing motion for 20 seconds but without excessive force that induces substantial bending of a disposable applicator. Both flowable and sculptable composite resins have been successfully used with some clinicians applying and polymerizing a layer of flowable composite resin and then adding an external layer of sculptable composite resin to provide enhanced resistance to wear. When caries is present, silver diamine fluoride has been used to arrest the caries rather than restore the lesion. Noncarious cervical lesions (NCCLs) form as smooth saucerlike depressions or as V-shaped notches. Prevalence values as high as 90% and as low as 10% have been reported due to habits such as excessive toothbrushing and an acidic diet. Occlusal factors have been proposed as contributing to their presence but it remains controversial. Publications have both supported and challenged the concept of abfraction. They are one of the most common demineralization diseases in the body. Conservative treatment through prevention is recommended with restorative treatment delayed as long as possible. When treatment is needed, composite resins are commonly used with proposed restorative guidelines including texturing the sclerotic dentin, beveling the enamel, potential use of mechanical retention, 30 seconds of acid etching, and use of either multistep or single-step adhesives in conjunction with a light scrubbing motion for 20 seconds without excessive force placed on disposable applicators.

To etch or not to etch, Part II: On the hydrophobic-rich content and fatigue strength of universal adhesives

ObjectiveTo determine whether smear layer management, via conservative etching protocols, and the hydrophobic-rich content of hybrid layers would affect the fatigue strength of resin-dentin interfaces. MethodsBar-shaped dentin beams obtained from sound third molars were wet-polished for 30 s. Dentin was etched with 32 % ortho-phosphoric acid for 3 or 15 s, 10 % meta-phosphoric acid for 15 s or by a prime-and-rinse application using a mild universal adhesive (Scotchbond Universal, 3M ESPE). Self-etch application served as control. Coating was performed with a solvent-free bisGMA-based resin. Composite buildups were made with a nanofilled composite. Resin-dentin beams with twin-bonded interfaces were sectioned and stored in deionized water for 24 h at 37 ℃ before 4-point flexural quasi-static monotonic testing (n = 16). Stress-life fatigue behavior was evaluated under cyclic loading (n = 35) by the staircase method at 4 Hz. The tension side of cyclic-loaded unfractured beams were evaluated under SEM, along with the micro-morphology of etched dentin surfaces. Monotonic data was analyzed by two-way ANOVA followed by the Tukey Test and cyclic-loaded data by Kruskal-Wallis on Ranks (α = 0.05). ResultsEtching protocols and higher hydrophobic-rich content produced significantly higher fatigue life distributions (p < 0.05). Dentin demineralization was ranked as OPA 15 s > MPA 15 s > OPA 3 s > P + R > SE. Less aggressive etching and coating reduced crack formation at hybrid layers. SignificanceCurrent oversimplification trends in resin-dentin bonding constitute a trade-off between hybridization quality and easier adhesive handling. Controlled dentin etching and increasing the hydrophobic-rich content of hybrid layers may be necessary to extend the longevity of mild universal adhesives.

METHOD OF MOLAR SURFACE RESTORATION FOR TREATMENT OF PIT-AND-FISSURE CARIES IN CHILDREN

Lesions of permanent teeth are diagnosed shortly after their eruption and the largest percentage of lesions is found in the first permanent molars, and in 100% of cases it is a pit-and-fissure caries. Considering this progress, the features in children caries may be unnoticed for definite period and be revelaed only during preventive checkups, when the defect is identified in the fissure or pit while the occlusal surface remains intact.&#x0D; Occlusal surface restoration after preparation of the carious cavity requires the knowledge of anatomical features of molars, certain skills, experience in modeling cusps, slopes, fissures and pits and, of course, doctor’ attention. Lately, the restorative dentistry has used a method of the occlusal stamp restoration for restoration of occlusal surfaces.&#x0D; The purpose of our study is to use the occlusal stamp restorative technique for restoration of occlusal surfaces of molars in children.&#x0D; This technique was used in 10 children aged 8 from 12 years old, who visited the department of pediatric dentistry with the aim of prevention of dental diseases.&#x0D; Examination of children revealed carious cavities in the first permanent maxilary (3) and mandibular (7) molars. In all cases the carious cavities were diagnosed in the pits or fissures of the occlusal surface. The carious cavities had narrow inlets and the enamel of the occlusal surface was preserved but discolorated. The mentioned restorative method was performed in all cases according to the following algorithm.&#x0D; Appropriate topical and infiltrative anesthesia was provided for patients, teeth were isolated with the rubber-dam, the tooth surface was cleaned and the occlusal stamp was made with “Latelux Flow” flowable composite in the following way: a portion of liquid composite was applied on the dry occlusal surface of the tooth and spread with dental applicator (Latus, Ultrafine). Then, a small portion of flowable composite was added to the area of the the microapplicator`s head and the composite was photopolymerized.&#x0D; The occlusal stamp was removed with a dental probe after polymerization, its quality was assessed and the carious cavity was prepared according to biological feasibility principles, which included standard steps. After preparation the total etching of enamel (30 sec) and dentin (15 sec) with orthophosphoric acid ("Conditioner 36", "Dentsply") was performed. After washing and drying, Prime &amp; Bond Universal adhesive was inseted additionally to the carious cavity, dried, and polymerized. Liquid SDR composite (Dentsply) was added to the cavity as an adaptation layer, polymerized, and the rest of carious cavity was restored with nanohybrid composite CeramX SphereTEC one. (Dentsply).&#x0D; The last layer of material which was placed in the cavity was formed with the occlusal stamp. Firstly, the material was adjusted with a modelling spatula then Teflon tape was applied on surface and the stamp was placed on it. After the using of light pressure, the stamp and Teflon tape were removed, exceeds of material were extracted with a modelling spatula, the composite was adjusted to the tooth tissues along the restoration margins with a microapplicator, and then all the composite was polymerized. Furtherly, the stage of checking of the occlusal contacts was performed. Usually, the restoration were made with the occlucal stamp technique demanded minial occlusal corrections. The final stage was the finishing and polishing of the restoration.&#x0D; The stamp technique for restoration of occlusal surface allows minimize the time needed for modelling and adjustment of interocclusal contacts, which is very actual during the work with children and therefore can be recommended for general usage in clinical practice of pediatric dentistry.

A comprehensive in vitro study on the performance of two different strategies to simplify adhesive bonding

ObjectiveThe purpose of this study is to compare the bonding performance and mechanical properties of two different resin composite cements using simplified adhesive bonding strategies.Materials and methodsShear bond strength of two resin composite cements (an adhesive cement: Panavia V5 [PV5] and a self‐adhesive cement: RelyX Universal [RUV]) to human enamel, dentin, and a variety of restorative materials (microfilled composite, composite, polymer‐infiltrated ceramic, feldspar ceramic, lithium disilicate and zirconia) was measured. Thermocycle aging was performed with selected material combinations.ResultsFor both cements, the highest shear bond strength to dentin was achieved when using a primer (PV5: 18.0 ± 4.2 MPa, RUV: 18.2 ± 3.3 MPa). Additional etching of dentin reduced bond strength for RUV (12.5 ± 4.9 MPa). On enamel, PV5 achieved the highest bond strength when the primer was used (18.0 ± 3.1 MPa), while for RUV etching of enamel and priming provided best results (21.2 ± 6.6 MPa). Shear bond strength of RUV to restorative materials was superior to PV5. Bonding to resin‐based materials was predominantly observed for RUV.ConclusionsWhile use of RUV with the selective‐etch technique is slightly more labor intensive than PV5, RUV (with its universal primer) displayed a high‐bonding potential to all tested restorative materials, especially to resin.Clinical significanceFor a strong adhesion to the tooth substrate, PV5 (with its tooth primer) is to be preferred because etching with phosphoric acid is not required. However, when using a wide range of varying restorative materials, RUV with its universal primer seems to be an adequate option.

Effect of Active Bonding Application after Selective Dentin Etching on the Immediate and Long-Term Bond Strength of Two Universal Adhesives to Dentin.

The objective was to evaluate the influence of active bonding applications (ABA) for different time intervals after selective dentin etching (SDE) for 3 s on the microtensile bond strength (μTBS) to dentin of two universal adhesive systems (UAs): one containing 2-hydroxyethyl methacrylate (HEMA) (Scotchbond Universal, SBU), and one that was HEMA-free (Prime&Bond Universal, PBU). Dentin bovine specimens were divided into four groups: self-etch as control (SE), SDE + ABA for 15 s (SDE15), SDE + ABA for 20 s (SDE20), and SDE + ABA for 25 s (SDE25). The μTBS test was performed after a water storage of 24 h and 6 months. Scanning electron microscopy (SEM) was used in order to examine the resin–dentin interface. For the PBU, the µTBS was significantly influenced only by the aging factor (p < 0.026). A statistically significant decrease in the µTBS after 6 months of aging was observed only for the SDE15 group. For SBU, µTBS was significantly influenced by the protocol application and the aging time (p ≤ 0.041). The groups SDE15, SDE20, and SDE25 achieved statistically significant higher values (after 24 h and 6 months). No considerable variances were noticed in the homogeneity and continuity of the hybrid layer (HL) among the groups. In conclusion, SDE and ABA improved the µTBS only of a HEMA-containing universal adhesive.

Remineralization potential and biocompatibility of titanium dioxide-doped phosphate glasses

This study reports the remineralizing potential and biocompability of titanium dioxide doped phosphate glass (TDPG). Glass paste was prepared with polyacrylic acid and applied as a thin coat on etched dentin for different periods. Normal and etched dentin were used as controls. Remineralization potential was tested using atomic force microscopy, scanning electron microscopy coupled with energy dispersive x-ray and Raman spectroscopy. The biocompability was tested using XTT assay and human dental pulp stem cells. After 5 days of paste application, some angular or plate-like crystals were observed occluding some dentinal tubules and precipitated within intertubular dentin. After 14 days, these crystals form a thin, uniform layer, consistent with vsP–O–P, vasPO2 and vsPO peaks and has ions detected in the glass, covering the dentin surface. By 30 days, the thickness of this layer and intensity of detected peaks increased to completely obscure the underlying dentin apatite peak. By 77 days, additional glass peaks were identified. The glass extract showed comparable or significantly higher cell viability than positive control. ConclusionTDPG paste could be a suitable material for remineralization of affected dentin.

Influence of Etching Methods on the Shear Bond Strength of a Influence of Etching Methods on the Shear Bond Strength of a Universal Adhesive System to Sound and Artificial Caries-Affected Universal Adhesive System to Sound and Artificial Caries-Affected Dentin

Purpose:This study tested the bond strength of a universal adhesive system to both caries-affected (CAD) and sound dentin after using different etching techniques. Methods: Forty premolars were wet grinded to expose flat occlusal midcoronal dentin. Specimens were equally divided according to the substrate into sound and (CAD) specimens which were exposed to pH- cycling for 14 days. Single Bond™ universal adhesive was used to bond each dentin substrate either after no etching or etching of dentin, after which, resin composite was used for build-up. These specimens were then tested for shear bond strength (SBS). The results were then analyzed by two-ways ANOVA. Results: Single Bond™ universal bonded to sound dentin had statistically significantly higher SBS mean values compared to CAD. Single Bond™ applied after separate etching step of dentin showed a statistically higher SBS compared to self-etching method when bonded to sound dentin. Conclusion: Separate etching improved bonding to sound dentin and did not influence the bond strength of tested universal adhesive to CAD.

Mechanical Stability and Proteolytic Activity of Resin–dentin Bonds Using the Cross-linked Dry Bonding Technique

To evaluate the mechanical stability and the proteolytic activity of bonds created by a two-step, etch-and-rinse adhesive applied to cross-linked and air-dried etched dentin. Flat dentin surfaces were produced in 64 extracted sound human molars. The dentin was etched with 35% phosphoric acid for 15 seconds, and then the teeth were divided into groups according to the cross-linking solution applied on the etched dentin. Group 1: 5% grape seed extract (GSE), Group 2: 5% glutaraldehyde, Group 3: Gluma Desensitizer, or Group 4: deionized water (control). Solutions were applied for 60 seconds, followed by rinse and blot drying. Then, the teeth were separated into two subgroups where the etched dentin was kept moist or air-dried. The adhesive was applied followed by a composite resin buildup. After 24 hours, the teeth were cut into beams (0.81 mm²) that were tested for microtensile strength immediately or after 12 months of aging in a 37°C saliva-like buffer. Additional teeth (n=32) were bonded as described and cut into 0.5-mm-thick slabs. The slabs were prepared for nanoleakage (scanning electron microscopy) and in situ zymography (EnzChek Protease Assay Kit). Bond strength data were submitted to ANOVA and Tukey tests (α =0.05). Significant reduction in immediate bond strength (ca 65%) and increase in proteolytic activity was seen when the etched dentin was air dried without previous cross-linking biomodification. Conversely, bond strengths did not differ from those produced on wet dentin when collagen was cross-linked before air drying, irrespective of the solution applied. For both moist and air-dried etched dentin, collagen cross-linking resulted in mechanically stable bonds and reduced proteolytic activity after 12 months of storage. Bonds produced by the application of a two-step, etch-and-rinse adhesive to cross-linked, air-dried, etched dentin were mechanically stable and revealed reduced proteolytic activity after 1 year of aging.