Dentin Smear Layer Research Articles

Effect of inositol hexaphosphate acid versus polyacrylic acid on dentin properties and adhesion of a self-adhesive restorative material to dentin

ObjectiveThis study evaluated the effect of 2% inositol hexaphosphate (IP6) and 10% polyacrylic acid (PAA) on dentin surface micromorphology, matrix/mineral ratio, microhardness, and resin−dentin shear bond strength (SBS) of a self-adhesive restorative material (Surefil™ One; Dentsply Sirona, Konstanz, Germany). Materials and methodsHuman permanent molar mid-coronal dentin discs were either not treated (control), conditioned with 10% PAA (Dentin Conditioner, GC, Tokyo, Japan) for 20 s, or etched with 2% IP6 for 20 s. Dentin surface micromorphology (etching pattern), matrix/mineral ratio, and microhardness were characterized by a scanning electron microscope (SEM), a confocal Raman microscope and a microhardness tester using the Vickers indenter, respectively. Sound molars were cut flat, mounted, surface treated and restored with Surefil™ One, Dentsply. The shear bond strength (SBS) was evaluated using a universal testing machine at 24 h and after 10k thermo-cycles. The failure modes were assessed. One-way and two-way analysis of variance (ANOVA) followed by the Tukey's multiple comparisons test was used for the statistical analysis. ResultsIP6 etching resulted in a more aggressive and uniform etching pattern compared with PAA. The mineral/matrix and Vickers microhardness of IP6-etched dentin were significantly less than those of PAA-conditioned dentin. IP6 etching significantly improved the resin−dentin SBS compared with the control group (no treatment) at 24 h and after thermo-cycling. Adhesive failures were the most predominant in all study groups. ConclusionInositol hexaphosphate acid etching deteriorated dentin microhardness and resulted in substantial demineralization, however, it eliminated the dentin smear layer completely and created marked micromorphological alteration at dentin surface, significantly increasing the resin−dentin SBS of a self-adhesive restorative material.

The Capability of Cocoa Pulp Juice (Theobroma cacao L.) on Crown Dentin Smear Layer Removal

Introduction: smear layer is a thin layer formed from tooth structure instrumentation which can prevent the restoration material bonds the tooth structure. Partial smear layer should be removed using dentin conditioner. One of dentin conditioners that is often used is 10% polyacrylic acid. The natural ingredient that is thought to be an alternative to dentin conditioner is cocoa pulp juice because it contains many acidic compounds. Methods: This research is a laboratory experimental study to determine the ability of 100% cocoa pulp juice (Theobroma cacao L.) to remove the crown dentin smear layer and compare it to 10% polyacrylic acid. Eight dental elements were prepared for class I cavities on the middle 1/3 of buccal surface to reach 3 mm in diameter and 2 mm in depth, enamel was prepared until 1 mm in depth of cavity left. The samples were irrigated with sterile aquades and dried. Furthermore, 4 samples were applied 10% polyacrylic acid and 4 samples used cocoa pulp juice, left for 20 seconds, irrigated, dried, and put in the oven for 2x24 hours. The samples were examined for their cavity cleanliness score using Scanning Electron Microscope (SEM) photo with 2000x of magnification. Result: both groups have the same score and statistical test shows that there is no significant difference between them. Conclusion: the 100% cocoa pulp juice was able to clean the smear layer of crown dentin and its ability equal to 10% polyacrylic acid.

Resin-Based Cement Applied to Enamel and Dentin Pre-Treated with Phytic Acid: An In Vitro Study

Phytic acid (IP6) has the ability to etch tooth structure due to its acidity and chelating properties. This study aimed to evaluate the micro-tensile bond strength (μTBS) of resin-based cement to enamel and dentin using manufacturer-provided etchants, phosphoric acid (PA) for enamel and a mixture of 10% citric acid and 3% ferric chloride (CAF) for dentin and compare them to IP6. Enamel surfaces were etched for 30 s with either PA or IP6 (1%, 5% or 10%). Dentin surfaces were etched for 15 s with either CAF or 1% IP6. Pre-polymerized composite blocks were bonded to enamel and dentin surfaces. After 24 h, the specimens were sectioned into beams and subjected to μTBS testing. De-bonded specimens and smear layer removal were analyzed with a scanning electron microscope. Etching enamel with 1% and 5% IP6 resulted in μTBS values that are comparable to the control (PA) (p > 0.05), while 10% IP6 negatively affected the μTBS (p < 0.05). The μTBS to dentin etched with 1% IP6 was higher compared to the control (CAF) (p = 0.001). IP6 effectively removed enamel and dentin smear layer, and at specific concentrations, it may be a suitable alternative conditioner agent for bonding resin-based cement to enamel and dentin.

Scanning Electron Microscope Image Analysis of Bonding Surfaces following Removal of Composite Resin Restoration Using Er: YAG Laser: In Vitro Study.

It is impossible to remove tooth-colored restorations by mechanical means without unnecessary damage to the adjacent sound tooth structure. This study is aimed at investigating erbium-doped yttrium aluminum garnet (Er: YAG) laser (Hoya ConBio, VersaWave, CA, USA) in removing composite resin restorations and assessing the change in morphology of bonding surfaces using a scanning electron microscope (EDX, CAMSCANNER, 3200LV, UK). The investigators collected thirty extracted sound human premolar teeth for this investigation, and the conventional design class V cavity was prepared on the buccal surface of each specimen. The specimens were allocated randomly into three groups, according to the procedure used for the ablation of the composite restoration: group A (high-speed diamond fissure bur), group B, and group C (Er: YAG laser) using a different pulse repetition rate of 20 Hz (group B) and 25 Hz (group C). The AutoCAD software program (Autodesk, Inc., 2016) was used to calculate the surface area and the resulting dimensional change of the cavities after restoration removal. The cavities were filled with composite resin and randomly assigned into two groups conforming to the methods applied to eliminate the restoration; diamond turbine fissure bur and laser. In each group, two specimens were selected randomly for scanning electron microscope analysis of bonding surfaces. The least meantime for the composite resin removal was observed in the high-speed diamond bur, significantly less than both Er-YAG laser groups (p < 0.001). However, at a higher pulse repetition rate, time-consuming decreased. The results showed that laser is more conservative in removing composite resin restoration as the change was most remarkable in group A (0.800 mm), then group C (0.466 mm), and the slightest change is in group B (0.372 mm) (p = 0.014). The dentin surface of group A showed a smooth surface with no opened dentinal tubule and intact smear layer. In groups B and C, dentin surfaces were irregular, scaly, or flaky, and dentinal tubules were opened without a smear layer. Therefore, Er: YAG laser is effective for composite resin removal considering the parameters chosen in this study with fewer changes in cavity surface area and better microretentive features.

Bonding Performance of Self-etching Adhesives to Bur-cut Dentin with Active Application Mode.

This study evaluated whether active application of self-etching adhesives would influence their microtensile bond strength (µTBS) to dentin cut with burs of different grit sizes. Eighty-four human premolars were divided into 12 groups according to 1) two dentin surface preparations with either superfine- or regular-grit diamond burs; 2) three adhesives - Clearfil SE Bond 2 (SE2), Scotchbond Universal (SBU, 3M Oral Care) and G-Premio Bond (GPB, GC); and 3) two application modes of each adhesive (active or passive). Six bonded teeth per group were sectioned into sticks for µTBS testing. Statistical analyses were performed using 3-way ANOVA followed by Duncan's test (p < 0.05). Additional teeth were prepared to observe the interaction between the dentin smear layer obtained from each bur with adhesives under different application modes using transmission electron microscopy (TEM). Active application significantly increased the dentin bond strength of SE2, irrespective of the kind of bur used (p < 0.05). The highest bond strength of SBU was observed when bonded to superfine-grit diamond bur-cut dentin with the active application. There was, however, no influence of the tested factors on GPB group (p > 0.05). TEM observation showed that active application promoted dentin smear layer dissolution in all adhesive groups. Bond strengths of self-etching adhesives to dentin are influenced by bur-cut smear layers and mainly by application mode of adhesive materials. Active application improves µTBS of self-etching adhesives by enhancing smear layer modification and resin penetration into bur-cut dentin.

Effect of smear layer deproteinization with enzyme solutions on bonding efficacy of one-step self-etch adhesives

ObjectiveThe aim of this study was to evaluate the deproteinizing/pretreatment effect of enzyme solutions on cavity adaptation and bond strengths to enamel and dentin. Materials and methodsClass V cavities with enamel and dentin margins were prepared using bovine incisors. After one of four pre-treatments (bromelain, papain, HOCl-solution and none), Scotchbond Universal (SU) or Clearfil Universal Bond Quick (UQ) was applied to the cavities, followed by filling resin composite. After water storage for 24 h, the interfacial gap lengths were calculated using SS-OCT. In addition, the micro-shear bond strength (μSBS) test to flat enamel and dentin surfaces treated as mentioned above was performed. Furthermore, the enamel and dentin surfaces after the pretreatments were morphologically investigated using a scanning electronic microscopy (SEM). ResultsThe pretreatment of bromelain and HOCl-solutions significantly increased μSBS of SU to enamel and dentin, and improved enamel-marginal and internal adaptations in the cavity (p < 0.05), however for UQ, they could not significantly improve the enamel- and dentin-marginal adaptations (p > 0.05) although they significantly increased μSBS to dentin (p < 0.05). On the other hand, pretreatment with papain did not result in any improvements (p > 0.05). SEM observations revealed that treatments of bromelain and HOCl-solutions partially removed the dentin smear layer, while papain treatment slightly thinned it. ConclusionPretreatment with bromelain could increase μSBS to enamel and dentin, and improve the cavity adaptation due to partial dissolution of the organic phase in the smear layer.

Effect of smear layer deproteinization with chemo-mechanical caries removal agents on sealing performances of self-etch adhesives

ObjectivesTo evaluate the sealing performance of self-etch adhesives (SEA) after smear layer deproteinization with chemo-mechanical caries removal agents (CRA) to enamel and dentin cavity walls in comparison with 6% NaOCl smear layer deproteinizing. MethodsEighty extracted bovine incisors with tapered cylindrical cavities (2.5 mm upper diameter, 1.5 mm lower diameter, 2 mm depth) at the cemento-enamel junction were randomly divided into four pre-treatment groups; no treatment (control), Papacarie (papain enzyme-based CRA), Carisolv (NaOCl-based CRA), and 6% NaOCl. After pretreatment, G-Bond Plus (GBP, one-step SEA) or Clearfil SE Bond 2 (CSE, two-step SEA) was applied to the pre-treated cavity, and then filled with a flowable resin composite (Clearfil Majesty ES Flow). Gap formations at the enamel and dentin lateral walls, and on the dentin cavity floor were investigated using swept-source optical coherence tomography (SS-OCT) after 24-h water storage at 37 °C. Deproteinizing effects of the tested agents on smear layer-covered enamel and dentin were quantified by changes in the amide:phosphate ratio using ATR-FTIR analysis. ResultsPapacarie significantly reduced gap formation with both self-etch adhesives at all locations, compared to the control group (p < 0.05). In contrast, increased gap formation was observed with Carisolv and NaOCl. In most groups, CSE exhibited significantly lower gap formation than GBP (p < 0.05). ATR-FTIR revealed a significant decrease in the amide:phosphate ratio for all the deproteinizing agents (p < 0.05). ConclusionsChemo-mechanical CRAs could effectively remove the organic phase of enamel and dentin smear layer. The papain enzyme-based gel Papacarie could improve the sealing performance of the self-etch adhesives to both enamel and dentin.

Effect of a novel prime-and-rinse approach on short- and long-term dentin bond strength of self-etch adhesives.

This study investigated the effects of the prime-and-rinse approach, using a 10-methacryloyloxydecyl dihydrogen phosphate (MDP)-containing primer, on the short- and long-term dentin microtensile bond strengths (MTBSs) of mild self-etch adhesives. Half of sixty human midcoronal dentin surfaces were polished as control (self-etch approach), and the other half were polished and further treated with a 15% MDP-containing primer and thoroughly sprayed with water as prime-and-rinse approach. The dentin surfaces were treated with a self-etch adhesive, and a composite resin was placed on the surfaces. The following materials were used: Clearfil S3 Bond+Clearfil Majesty; G-Bond+Gradia Direct; Adper Easy One+Z250; and i Bond+Charisma. The MTBS was examined after 24h and 14months in water storage. The resin-dentin interfaces were analysed using scanning electron microscopy/transmission electron microscopy. Pretreated dentin surfaces were further analysed using scanning electron microscopy and micro-Raman spectroscopy. Compared with the self-etch approach, the prime-and-rinse approach significantly increased the dentin MTBS, regardless of the duration of storage. The scanning electron microscopy/transmission electron microscopy findings revealed that the prime-and-rinse approach removed most of the dentin smear layer. The Raman spectra of the MDP-treated dentin reveal the characteristic spectra of collagen, hydroxyapatite, and the monomer. Therefore, the prime-and-rinse approach using MDP-containing primers prior to the application of mild self-etch adhesives significantly increases the short- and long-term MTBS of dentin.

Assessment of Cleaning Effect of Irrigation Time Using 5.25% Sodium Hypochlorite and Aspiration with Endovac

The aim of this study is to determine whether there is a link between the 5.25% sodium hypochlorite irrigation time using Endovac and the endodontic space cleaning quality. The study was done on teeth with a root length of more than 12 mm that did not undergo previous endodontic treatments and had a closed apex. All roots where mechanically prepared and the irrigation protocol was applied acording to the established protocol. The root canal surface was explored by electronic microscopy. A score was given to each image regarding remaining debris and smear layer. The comparative analysis of experimental data shows, that there are no statistically significant differences between the study groups regarding debris and smear layer removal. None of the techniques used in the present study has led to the complete removal of dentinal detritus and root smear layer.

СОВРЕМЕННЫЙ ВЗГЛЯД НА АНТИБАКТЕРИАЛЬНУЮ ОБРАБОТКУ КОРНЕВОГО КАНАЛА С ПОМОЩЬЮ ЛАЗЕРНОЙ ФОТОДИНАМИЧЕСКОЙ ТЕРАПИИ

Importance. Currently, endodontic dental treatment is a complex manual process that requires in-depth knowledge of the anatomy of the crown and root part of the tooth, all this is necessary, as is a three-dimensional assessment of the structure of the pulp chamber of the root canal system, using modern technologies. In other words, a favorable result of endodontic treatment can be achieved in case of correct formation of access to the root canals and the qualitative removal of any inflamed, infected, degeneratively altered and necrotized pulp tissues.&#x0D; Objectives ― the study of the antibacterial effect and the possibility of using a laser photodynamic system for antibacterial treatment of root canals containing fragments of endodontic instruments.&#x0D; Methods. Fifteen patients aged from 18 to 50 years with 20 root canals containing fragments of an endodontic instrument were selected for work, previously treated for chronic periodontitis. Three samples for microbiological examination were taken: before the start of treatment, the sampling of dentinal chips from the root canal with a sterile file (sample A), after the instrumental treatment, medical treatment with 2.25 % sodium hypochlorite solution and the sampling of dentinal chips from the channel wall (sample B). Further, a photosensitase solution was placed in the root canal for 60 sec., Exposure was carried out with a laser beam for 120 seconds (HELBO system, Austria), dentinal chips collected (Sample C).&#x0D; Results. In samples A, the infection level corresponded to 4 points (marked bacterial load); in samples B ― 2 (average); in samples C ― 0. &#x0D; Conclusions. The use of a laser photodynamic system in the root canals, provides a high therapeutic effect, accelerates the process of medical treatment of the canal canal, by removing the dentinal chips and smear layer.

Influence of the dentin smear layer trait on the bond strength of the self-adhesive resin cements

This work aimed to evaluate the influence of smear layer on the bonding effectiveness and durability of the self-adhesive resin cements to dentin. A total of 48 fresh caries-free third molars with exposed dentin surface were divided into two groups. The dentin surfaces were treated using a standard grit diamond bur (group A) or further polished using a fine grit diamond bur (group B) and then bonded with either of the two self-adhesive resin cements, namely, Clearfil SA Cement (CSA, Kuraray) and Multilink Speed (MS, Ivoclar Vivadent). After 24 h or 2-year water storage, a microtensile bond strength test was performed. In group A, the dentin surface was rough, the smear layer was thick, and the dentin tubule orifice detritus showed low embolism value. In group B, the dentin surface roughness decreased, the embolism proportion increased, and the smear layer became thin. The initial bonding strengths of CSA and MS in group A were significantly lower than those in group B (P<0.05). The bonding strengths of CSA and MS significantly decreased after two years of water storage (P<0.05). For CSA, the bond strength of group B was significantly lower than that of group A (P<0.05). For MS, the differences in the bonding strength between groups A and B were insignificant (P>0.05). The properties of the smear layer and the types of self-adhesive resin cement used affected the bond strength and durability.

Investigation of the Effect of Er:Cr:Ysgg Laser 2780 nm in Comparison with xp-Endo Finisher on Root Canal Dentin Permeability and Smear Layer Removal: An In Vitro Study

The aim of this study was to assess the effect of Er:Cr:YSGG 2780nm laser in comparison with Xp-endo Finisher in elimination of smear layer in terms of root canal dentin permeability and SEM analysis. Method: twenty-eight single-rooted extracted lower premolars were instrumented up to size X4 (protaper Next, Dentsaply) and divided into two groups according to the irrigation system, first group activated by Xp-endo Finisher and second one by Er:Cr:YSGG laser 2780 nm, pulsed mode, 1.25 W. Afterward, the roots were made externally impermeable, filled with 2%methylene blue dye, divided horizontally into three segments representing the apical, middle, and coronal thirds then examined under stereomicroscope. Using analytical software, the root section area and dye penetration area were measured, and then, the percentage of net dye penetration area was calculated. Moreover, scanning electron microscope investigations were accomplished. Results The non-parametric Mann-Whitney U test was done and showed a highly significant difference between the two experimental groups over the three root thirds. Dye penetration in Erbium laser group was significantly higher over the whole root length compared to other group. Scanning electron micrographs of Erbium laser group showed a distinctive removal of smear layer with preservation of the annular structure of dentinal tubules, while Xp-endo finisher group result in uneven removal of smear layer, and the dentinal tubules appear in sickle shape which indicate that they are partially opens especially in the apical third.

Comparative SEM Study on the Effect of Irrigating the Radicular Dentine with NaOCl and EDTA Through Conventional Techniques and Diode Laser

Since there are not many references in literature about the action of diode laser 940nm on the dentin and root smear layer, the aim of this study is to evaluate and compare, through SEM analysis, the efficiency of the Sodium hypochlorite 2% (CERKAMED) - EDTA 17% (CERKAMED) combination, operated in the middle and apical third of the root, by conventional syringe needle EndoEze and diode laser 940nm treatment. The study was performed on 40 single-root teeth, which were divided into two groups: group A consisting of 20 teeth, for which irrigation was performed only with the syringe and a top open side needle EndoEze Irrigator, resulting in a turbulence moving upward which efficiently irrigates the root canal and prevents periapical water solution; and group B consisting of 20 teeth, which benefited from irrigation associated with diode laser 940nm treatment. In the middle third and apical third smear layer removal was more effectively achieved when teeth benefited from irrigation associated with the laser diode treatment. In Endodontics, Diode laser is a good decontamination system, with biostimulation effect, which is important in healing the periapicale area. Significantly better results were obtained using 940nm laser diode associated with successive irrigation with 2% NaOCl and 17% EDTA, as compared to the conventional technique performed by syringe and lavage needle EndoEze Irrigator (Ultradent).

Dentin-smear remains at self-etch adhesive interface

ObjectiveThe bonding potential of ‘mild’ self-etch adhesives may be compromised due to smear interference, as they may not dissolve/penetrate the smear layer effectively due to their relatively low acidity. We observed that the thickness of the dentin smear layer differed depending on the surface-preparation methodology used. MethodsThe interaction of an (ultra-)mild self-etch adhesive (Clearfil S3 Bond, Kuraray Noritake) with human dentin, prepared either using a medium-grit diamond bur (‘thick’, clinically relevant smear layer) or 600-grit SiC-paper (‘thin’ smear layer), or just fractured (smear-free), was evaluated using high-resolution transmission electron microscopy (TEM). Non-demineralized/demineralized 30–100nm interfacial cross-sections were prepared following common TEM-specimen processing and diamond-knife ultra-microtomy. ResultsThe adhesive did not dissolve the bur-cut, nor the SiC-ground smear layer, but impregnated it. Within this ‘resin-smear complex’, hydroxyapatite was abundantly present. At fractured dentin, this complex was not present, while the actual layer of interaction of the adhesive was limited to about 100nm. Non-demineralized ‘ultra-thin’ (30–50nm) sections confirmed the interfacial ultra-structure to differ for the three surface-preparation methods. An electron dense band was consistently disclosed at the adhesive interface, most likely representing the documented chemical interaction of the functional monomer 10-MDP with Ca. SignificanceThe dentin surface-preparation method significantly affects the nature of the smear layer and the interaction with the ultra-mild self-etch adhesive.

두 가지 다른 행정의 니켈 티타늄 파일의 성형 성상: 표면 성상, 상아질 삭편과 도말층에 대한 예비적 비교 연구

Purpose: To assess the surface profile of dentinal wall, dentin chips and smear layer during the canal shaping with rotary (ProTaper) and ProFile and reciprocating (WaveOne) nickel-titanium file. Materials and Methods: Sixty human extracted mandibular premolars and incisors with single canals were randomly selected. Three experimental groups (n = 20) were instrumented with ProTaper (F2), ProFile (25/.06), WaveOne (25/.08) with irrigation of 2.5% NaOCl. The dentin chips were collected from flute of file during each canal preparation. After canal preparation, roots were grinded and each group was divided into two subgroups (n = 10) for surface profile and smear layer of dentinal wall of shaped root canal. Each specimen was observed under scanning electron microscope for evaluating size of dentin chips, root canal surface recessions and smear layer. Scores of Smear layer were statistically analyzed using Kruskal Wallis test and Mann Whitney test at P = 0.05 level. Results: The size of dentin chips from ProFile, ProTaper and WaveOne was up to 7 µm, 6.5 µm, and 4 µm, respectively. In the surface profile, the width of surface irregularity was measured and Profile, ProTaper and WaveOne was up to 150 µm, 70 µm, and 80 µm, respectively. Completely cleaned root canals were not found. In the middle and apical third of the canals, WaveOne group showed higher smear layer score than ProFile and ProTaper groups (P < 0.05). Conclusion: Within limits of this study, reciprocating motion WaveOne group was not significant difference of shaping ability with the full-sequence ProFile and ProTaper systems except canal clearness of middle and apical third of root canal. When using WaveOne to shaping root canal, thorough root canal irrigation is recommended. (J Dent Rehabil Appl Sci 2014;30(2):121-30)

Sem evaluation of efficacy of rotary system in removal of smear layer with and without plastic f-file - An invitro study

Aim: To compare the effectiveness of the ProTaper and K3 Ni-Ti rotary instruments with and without F-file, regarding smear layer removal. Methodology: 60 extracted single rooted human mandibular premolar teeth were divided into two groups of 30 teeth each (group A and B). Both the groups were divided into two subgroups of 15 teeth each (group A had subgroups A1 and A2) and (group B had subgroups B1 and B2). In group A, all the 30 canals were subjected to cleaning and shaping with two different rotary system and kept unfinished. This group was named as unfinished group. In group B, all the 30 canals were subjected to cleaning and shaping with two different rotary system followed by finishing with plastic files. This group was named as finished group. The crown of each tooth was sectioned at the cement-enamel junction. Canals were prepared following conventional crown-down technique. After splitting the roots longitudinally, the dentinal smear layer of each root canal was evaluated in three areas (coronal, middle and apical thirds of the root) by means of numerical evaluation scale scoring system, using scanning electron microscope. Results:The statistical analysis was done using Mann-Whitney U-test and showed that there was better smear layer removal in finished group as compared to unfinished group in all the thirds of the root canal. Conclusion: After instrumentation with different rotary system, the use of plastic finishing files showed cleaner canal walls.

Effect of dentine smear layer on the performance of self‐etching adhesive systems: A micro‐tensile bond strength study

This study aimed to evaluate the effect of the smear layer on the micro-tensile bond strength when two self-etching adhesives were used with different techniques. Flat dentine surfaces were prepared using either medium grit diamond burs or tungsten carbide burs. Ten specimens from each prepared surfaces were subjected for smear layer evaluation under SEM. Forty specimens from each of the prepared surfaces were further divided into two groups, bonded with either Clearfil SE Bond (SE) or Clearfil S(3) Bond (S3) using one of four applications (as manufacturer's instructions, agitation, reapplication, and increased application time), restored with composites and subjected to a micro-tensile bond strength test. Smear layers created with diamond burs were thicker than those created with tungsten carbide burs. Surfaces prepared with tungsten carbide burs produced a higher bond strength than those prepared with diamond burs and the same type of adhesive resin. SE demonstrated a higher bond strength than S3 for all surfaces. S3 applied with the agitation technique demonstrated a higher bond strength to dentine prepared with tungsten carbide and diamond burs than that applied with other techniques. SE applied with increased time on dentine treated with carbide burs produced the highest bond strength. In conclusion, a thick smear layer decreased bond strength to dentine, and this might be improved by modification of application technique.

Effect of lactic acid irrigant on shear bond strength of Epiphany adhesive sealer to human dentin surface

To examine the effects of varied dilutions of lactic acid as a root canal irrigant and compare the shear bond strength of Epiphany adhesive sealer to human dentin surface with other solutions deemed to be suitable root canal irrigants. The occlusal surfaces of 60 extracted molar teeth were ground wet and treated with one of the following irrigants: 1) no irrigant (control); 1) 5% hydrogen peroxide; 3) 5% sodium hypochlorite; 4) 15% ethylenediaminetetraacetic acid (EDTA); 5) 10% lactic acid; or 6) 20% lactic acid. An additional specimen for each group was critical-point dried and freeze-fractured to evaluate the dentin surfaces after treatment by scanning electron microscopy. Specimens were treated with Epiphany primer, hollow steel tubes were placed on the dentin surfaces, and resin sealer (Epiphany) was applied to dentin inside the tubes. Specimens were stored in 100% humidity, then loaded to failure in a universal testing machine in the shear mode with a cross speed of 0.05 mm/min. Dentin surface treatment resulted in significant differences for surface topography and shear bond strength of Epiphany sealer (P < .001). Lactic acid and EDTA significantly improved epiphany- dentin bond strengths when compared with other irrigants (P < .001). The highest mean (SD) bond strength was 1.95 (0.47) MPa for dentin surfaces treated with 20% lactic acid. The lowest mean bond strength [0.41 (0.29) MPa] was associated with untreated dentin surfaces. Scanning electron micrographs showed that the surface of the control specimens had a smear layer that contained smear plug material. Similarly, hydrogen peroxide and sodium hypochlorite produced surfaces with a smear layer. Lactic acid solutions and EDTA, however, removed the dentinal smear layer but left remnants of smear plugs in the dentinal tubules. Lactic acid irrigant performed similarly to 15% EDTA and demonstrated higher bond strength of Epiphany sealer to dentin surface.

Determining the initial viscosity of 4 dentinal adhesives. Relationship with their penetration into tubuli

The main aim of this study was to determine the viscosity of four amelo-dentinal adhesives based on the same adhesion principles: the complete elimination of the dentinal smear layer using a 37% orthophosphoric acid and the building of a hybrid layer in a single stage. The secondary aim was to study the filling time for a tubulus using 2 approaches: analytically and using finite elements. The viscosity of four amelo-dentinal adhesive systems (Vivadent’s Syntac Sprint ®, De Trey Dentsply’s Prime & Bond 2.1 ®, Prime & Bond NT ® and Kuraray’s Panavia F ®) was determined using a viscometer (a StressTech ® rheometer) with a Couette rheometer-type tool mounted on it. A tubulus model was fixed: the assumption was of a cylindrical–conical cavity with its lower part closed, a depth of 11 μm, and a radius of more than 1.5 μm and less than 0.5 μm. This allowed us to perform an analytical study on the time it took these tubuli to be filled by the adhesives according to their viscosity and the various pressures involved when they were introduced into the dentinal tissue. The Forge 2 software application allowed us to reduce the geometry of the tubuli referring to a 3D problem to an axisymmetric 2D configuration. Thus modelling using finite elements was also performed and the results obtained by the two approaches were compared. The results from the analytical calculation and from the modelling showed different patterns of behaviour by the four adhesives with different viscosities at 25 °C: Syntac Sprint ®: 50×10 –3 Pa s, Prime & Bond 2.1 ®: 1.1×10 –3 Pa s, Prime & Bond NT ®: 1.4×10 –3 Pa s, Panavia F ®: 10 Pa s. The four adhesives would fill up the dentinal tubuli very quickly indeed. At identical surface tension values, the viscosity would have an influence on the filling time for the dentinal tubuli. Clinically, given the 20 s recommended by manufacturers in order for these products to impregnate the dentinal tissue, the viscosity of these adhesives did not appear to be a decisive factor in the formation of the hybrid layer.

Comparitive effects of tetracyclines and citric acid on dentin root surface of periodontally involved human teeth: A scanning electron microscope study

Periodontal diseases produce physical and chemical alterations in the root cementum. Various topical applications as root conditioning agents have been recommended as an adjunct to mechanical root surface debridement to remove smear layer, endotoxins and to expose collagen fibers on dentin surface. The objectives were to compare dentin surface changes following applications of tetracyclines and citric acid to the instrumented root surface of periodontally involved human teeth under scanning electron microscope.The study group comprised of 80 dentin samples, which were prepared from periodontally-compromised teeth, planned for extraction. Diseased surfaces were root planed. The teeth were sectioned and solutions of tetracycline HCl, minocycline, doxycycline and citric acid were applied to the surfaces with cotton pellets for 5minutes.The root surface samples were then examined by scanning electron microscope.Removal of smear layer in all the four groups was near total except a few areas. All four groups showed slight difference in mean number of total dentinal tubules. Minocycline and doxycycline showed no significant difference. The proportion of patent dentinal tubules was (74%) in tetracycline HCl group compared to minocycline (48.3%), doxycycline 42%), citric acid (52%), showing the differences statistically significant. Tetracycline group showed higher number of patent tubules when compared to minocycline, doxycycline and the difference was statistically significant.Results of this study suggest that tetracycline is the best current tetracycline form for root surface conditioning as measured by its ability to affect both dentin smear layer removal and tubule exposure.