"Enamel layering" using double-layered enamel-shade resin composites: The strategy to simulate the optical characteristics of human enamel.

OBJECTIVE: To evaluate the optical match between enamel and resin composites fabricated using mono-layered and double-layered techniques. MATERIALS AND METHODS: Enamel slabs were prepared from human upper incisors and canines. Mono-layered composite replicas were prepared from seven Filtek Z350XT and Estelite Sigma shades using silicone molds prepared from the respective enamel surfaces. Translucent and enamel shades (A2 or A3) of the two materials were produced from incisor molds for double-layered replicas, and the groups with the best results underwent accelerated aging. Spectrophotometric evaluation was performed using CIE color system. The differences in translucency (ΔTP) and color (ΔE00 ) between the enamel and paired composite replicas were calculated and analyzed using parametric statistics (α = 0.05). RESULTS: For the mono-layered composites, white enamel and translucent shades of Filtek yielded the lowest ΔTP for canines (4.6) and incisors (8.9), respectively. The ΔE00 of mono-layered replicas ranged from 5.1 to 11.8. Double-layered Filtek replicas displayed a better 1-day optical match with the lowest ΔTP (3.4-4.0) and ΔE00 (4.2-4.6), irrespective of each layer's thickness. CONCLUSIONS: For canines, the lowest ΔTP of Filtek white enamel was close to the acceptable threshold (4.43). For incisors, the thicker translucent double-layered Filtek composites demonstrated the greatest optical match before and after aging. CLINICAL SIGNIFICANCE: Upper incisors and canines have distinct enamel optical properties. Enamel layering using specific double-layered resin composites could achieve a better optical match with upper incisor enamel.

Bond Durability of a Repaired Resin Composite Using a Universal Adhesive and Different Surface Treatments.

PURPOSE: To evaluate the long-term effect of different surface treatments on the repair microtensile bond strength (µTBS) of resin composite using a universal adhesive. MATERIALS AND METHODS: Thirty-six resin composite blocks were fabricated and aged in 37°C distilled water for 1 month. The blocks were randomly assigned to different surface treatments: no treatment (control); diamond bur grinding (D); diamond bur + phosphoric acid cleaning (DP); diamond bur + silane application (DSi); diamond bur + phosphoric acid + silane (DPSi); and grit blasting with 50 µm H3PO4 particles + phosphoric acid + silane (APSi). Thereafter, Single Bond Universal adhesive was applied and repaired with the same composite. Composite-composite stick-shaped specimens were fabricated and subjected to the µTBS test either after 37°C water storage for 24 h or thermocycling for 10,000 cycles. Roughness of different surface-prepared specimens was measured by profilometer. Data were analysed using ANOVA and Duncan's post-hoc test (α = 0.05). Failure mode and micromorphology of different surface-prepared specimens were observed with SEM and EDS analysis. RESULTS: The highest µTBS was found in DPSi group at 24 h, and was significantly higher than others. The bond strengths in all thermocycled groups were significantly lower than those measured at 24 h. The highest µTBS was also found in the DPSi group, but this did not significantly differ from the DSi group. CONCLUSION: Thermocycling significantly reduced the repair bond strength. Diamond bur roughening with application of silane and universal adhesive yielded the highest repair bond strength for the aged resin composite.

Effects of dentin surface preparations on bonding of self-etching adhesives under simulated pulpal pressure.

Objectives: This study evaluated the effects of different smear layer preparations on the dentin permeability and microtensile bond strength (µTBS) of 2 self-etching adhesives (Clearfil SE Bond [CSE] and Clearfil Tri-S Bond Universal [CTS]) under dynamic pulpal pressure. Materials and Methods: Human third molars were cut into crown segments. The dentin surfaces were prepared using 4 armamentaria: 600-grit SiC paper, coarse diamond burs, superfine diamond burs, and carbide burs. The pulp chamber of each crown segment was connected to a dynamic intra-pulpal pressure simulation apparatus, and the permeability test was done under a pressure of 15 cmH2O. The relative permeability (%P) was evaluated on the smear layer-covered and bonded dentin surfaces. The teeth were bonded to either of the adhesives under pulpal pressure simulation, and cut into sticks after 24 hours water storage for the µTBS test. The resin-dentin interface and nanoleakage observations were performed using a scanning electron microscope. Statistical comparisons were done using analysis of variance and post hoc tests. Results: Only the method of surface preparation had a significant effect on permeability (p < 0.05). The smear layers created by the carbide and superfine diamond burs yielded the lowest permeability. CSE demonstrated a higher µTBS, with these values in the superfine diamond and carbide bur groups being the highest. Microscopic evaluation of the resin-dentin interface revealed nanoleakage in the coarse diamond bur and SiC paper groups for both adhesives. Conclusions: Superfine diamond and carbide burs can be recommended for dentin preparation with the use of 2-step CSE.

Role of the smear layer in adhesive dentistry and the clinical applications to improve bonding performance.

Currently, dental adhesives can be divided into two systems; a smear layer-removal approach with etch-and-rinse adhesives or a smear layer-modified approach with self-etching adhesives. After phosphoric acid etching, the smear layer is completely removed. More attention is, however, required when using self-etching adhesives. The smear layer is partially demineralized by the weak acidic monomer and subsequently incorporated into the hybrid layer. Therefore, the characteristics of the smear layer play an important role on the bonding performance of self-etching adhesives. Such characteristics, for instance, smear layer thickness and smear layer density, are influenced by many factors, e.g., instruments used for dentin surface preparation, cutting speed, and the abrasive particle size of the cutting instruments. This review discusses the contributing factors that affect the smear layer characteristics, and the influence of the smear layer on the bonding performance of dental adhesives. Also, the application techniques regarding how to improve the bonding performance of self-etching adhesives - the smear layer removal by using chemical agents, or the modification of the adhesive application procedures - are provided.

Effect of Stress Generated by Occlusal Cyclic Force on Class I Bulk-Fill Composite Restoration Microleakage.

OBJECTIVE: This study aimed to evaluate the effects of different types and restorative techniques of Class I composite restorations with a single loading force on stress distribution and cyclic loading force on microleakage formation. MATERIALS AND METHODS: Class I cavities were prepared in premolars with 4 mm depth and divided into six groups of different restorations with: (1) Filtek Z250; (2) a 3-mm-thick layer of Filtek Bulk Fill Flowable Restoration and covered with Z250; (3) a 1.5-mm-thick layer of flowable composite and covered with Z250; (4) lining all cavity with flowable composite and restored with Z250; (5) Filtek Bulk Fill Posterior Restoration; and (6) lining all cavity with flowable composite and restored with bulk-fill composite. The specimens with and without cyclic occlusal loading were subjected to microleakage observation. In addition, six different models of Class I restorations corresponding to the microleakage study were generated. Finite element analysis (FEA) was used to identify the stress distribution under a single loading force. STATISTICAL ANALYSIS: Data were statistically analyzed by two-way analysis of variance and multiple comparison. The significance level set at 0.05. RESULTS: Cavity lining or restoration with flowable composite underneath conventional composite reduced stress on composite resin based on FEA (groups 2 and 3). The cyclic stress on composite increased microleakage. Restoration with flowable composite underneath conventional composite reduced the microleakage in Class I restoration (groups 2, 3, and 4). CONCLUSION: The most effective cavity lining with a flowable composite underneath conventional composite restoration was stress reduction under loading force resulting in microleakage reduction.

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

PURPOSE: 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. MATERIALS AND METHODS: 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). RESULTS: 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. CONCLUSIONS: 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.

Efficacy of gel-based artificial saliva on Candida colonization and saliva properties in xerostomic post-radiotherapy head and neck cancer patients: a randomized controlled trial.

OBJECTIVE: To evaluate the efficacy of an edible artificial saliva gel, oral moisturizing jelly (OMJ), and a topical commercial gel (GC dry mouth gel) on Candida colonization and saliva properties. MATERIALS AND METHODS: This study was a secondary analysis of a single-blinded randomized controlled trial conducted in xerostomic post-radiotherapy head and neck cancer patients. Candida colonization, stimulated salivary flow rate (SSFR), saliva pH, and buffering capacity (BC) were measured at 0, 1, and 2 months after each intervention. Candida colonization was quantified by colony counts and species identified by Candida Chromagar, polymerase chain reaction, and API 20C AUX system. Statistical significance level was 0.05. RESULTS: A total of 56 participants in OMJ (N = 30) and GC (N = 26) groups completed the study. OMJ significantly increased saliva pH (p = 0.042) and BC (p = 0.013) after 1-month use, while GC only improved saliva pH (p = 0.027). Both interventions tended to increase SSFR but only GC had a significant increase at 2 months (p = 0.015). GC and OMJ significantly decreased the number of Candida species at 1 and 2 months, respectively. Both groups tended to reduce Candida counts but not significant. CONCLUSIONS: Both OMJ and GC saliva gels could improve saliva pH and decrease the number of Candida species. OMJ is superior to GC in its buffering capacity, while GC may better improve salivary flow rate. Long-term and large-scale study is warranted to test the efficacy of artificial saliva in oral health improvement. CLINICAL RELEVANCE: OMJ and GC gel could decrease the number of Candida species and improve saliva properties in post-radiation xerostomic patients. TRIAL REGISTRATION NUMBER: Clinicaltrials.gov NCT03035825. Date of registration: 25th January 2017.

Ultra-morphological characteristics of dentin surfaces after different preparations and treatments.

Using transmission electron microscopy (TEM), this study investigated the characteristics of smear layers after preparation of dentin surfaces using different methods. In addition, this study analyzed, using scanning electron microscopy (SEM), the interactions of smear layers with the various acidic agents used subsequently to treat the dentin surface. Mid-coronal dentin surfaces were prepared according to one of five instrumentation methods: fracture; grinding with carbide bur; grinding with regular-grit diamond bur; grinding with superfine-grit diamond bur; or grinding with 600-grit silicon carbide (SiC) abrasive paper. Then, each prepared dentin surface was further divided into control (no further treatment) or treatment with one of the following agents: phosphoric acid solution (PAS); phosphoric acid gel (PAG); Clearfil SE Bond 2 Primer (SE2); or Scotchbond Universal Adhesive (SBU). Longitudinal ultra-thin sections were made for TEM observations. Dentin discs, representing each surface preparation and treatment method described above, were created, and the morphology was examined by SEM. The TEM results revealed differences in thickness and denseness of the smear layer, according to the different methods of instrumentation used to prepare the dentin surface. The two forms of phosphoric acid completely removed the smear layer in all groups. Agglomerated silica particles were observed on the top of the collagen layer after etching with PAG. For all dentin surfaces, except for that prepared with SiC, SE2 demonstrated better etching efficacy on different smear layers, whereas SBU provided only superficial interaction.

Oral Candida colonization in xerostomic postradiotherapy head and neck cancer patients.

OBJECTIVES: To evaluate (a) oral colonization of Candida species, especially for non-albicans Candida species (NACS), in xerostomic postradiotherapy head and neck cancer patients and (b) risk factors affecting their colonization. MATERIALS AND METHODS: Subjective and objective dry mouth scores, stimulated salivary flow rates, pH and buffering capacity were measured in 72 xerostomic postradiotherapy head and neck cancer patients. Candida counts and species identification were performed using oral rinse samples cultured in Candida Chromagar, followed by polymerase chain reaction and API 20C AUX system. RESULTS: Candida colonization was observed in 87.5% of subjects, with 80.6% and 48.6% of study population colonized by C. albicans and NACS, respectively. NACS was associated with high objective dry mouth scores, denture use, and females (p = .006, .009, and .036, respectively). In addition, Candida glabrata was detected more in females (p = .018) and denture wearers (p = .026), while Candida tropicalis was associated with high objective dry mouth scores (p = .022) and females (p = .027). Quantity of Candida colonization correlated positively with objective dry mouth scores (r = 0.599, p < .001) and negatively with salivary flow rates (r = -0.258, p = .041) and pH (r = -0.290, p = .022). CONCLUSION: NACS colonization was common in xerostomic head and neck cancer patients. Increased signs of dry mouth, female and dental prostheses may promote NACS colonization.

Root Reinforcement after Obturation with Calcium Silicate-based Sealer and Modified Gutta-percha Cone.

INTRODUCTION: A root canal obturated with a calcium silicate-based sealer (bioceramic sealer [BCS]) and a modified gutta-percha cone (bioceramic cone [BCC]) might improve the fracture resistance of the root. The objective of this study was to evaluate root reinforcement of a bioceramic cone/sealer (TotalFill; FKG Dentaire SA, La Chaux-de-Fonds, Switzerland) by investigating the fracture resistance, push-out bond strength, sealer penetration, and modulus of elasticity (MOE) in comparison with gutta-percha/AH Plus (Dentsply Maillefer, Tulsa, OK) (GP/AH). METHODS: Eighty-four roots from bilateral mandibular premolars were prepared. For fracture resistance, 40 teeth were randomly divided into 4 groups (n = 10 each): intact roots (negative control), prepared roots (positive control), and the roots obturated with either BCC/BCS or GP/AH. Root canals were obturated with the matched single-cone technique and vertically loaded with a spreaderlike tip until fracture. For push-out bond strength (n = 10 each), coronal, middle, and apical root slices of BCC/BCS and GP/AH were loaded with a cylindrical plunger, and failure modes were determined. Sealer penetration of BCC/BCS and GP/AH (n = 12 each) was evaluated for the maximum depth and the circumferential and total area of penetration at the coronal, middle, and apical levels using confocal laser scanning microscopy. The MOE was investigated according to ISO 4049:2000. RESULTS: The fracture load of BCC/BCS, GP/AH, and the intact roots was not significantly different but significantly higher than the prepared, nonobturated roots. BCC/BCS provided a higher bond strength, maximum depth, and circumferential penetration at the apical root level as well as a greater sealer penetration area at all levels compared with GP/AH. The MOE of all materials was much lower than dentin. CONCLUSIONS: BCC/BCS and GP/AH bonded and reinforced the prepared roots; their fracture resistances were similar to the intact roots.

Effects of mechanical and chemical surface treatments on the resin-glass ceramic adhesion properties.

AIM: Intraoral repair of fractured ceramic restorations using resin composite is practical for dental treatment. In the present study, we investigated whether differences in surface treatments for glass ceramic would affect resin adhesion. METHODS: Leucite-reinforced glass ceramic plates (IPS Empress Esthetic) were ground with 320-grit silicon carbide paper, cleaned using phosphoric acid, and then etched with hydrofluoric acid (IPS Ceramic Etching Gel) or left unetched, and silanized using silane coupling agent (RelyX Ceramic Primer) or kept unsilanized. Either conventional (Adper Scotchbond Multi-Purpose) or universal (Scotchbond Universal) adhesive was used to bond the resin composite to ceramic surfaces. Specimens were subjected to microshear test after 37°C water storage for 24 h, and fractured surfaces were examined. Ceramic surface hydrophobicity after treatments was verified with contact angle measurements. Data were analyzed using anova and Tukey's tests. RESULTS: Regardless of the adhesive tested, hydrofluoric acid-etched ceramics showed higher bond strengths. Ceramic primer application improved resin bonding, even in non-etched groups, and also influenced fractography (P < 0.001). Contact angles on ceramics treated with ceramic primer were higher than those treated with silane-containing universal adhesive (P < 0.001). CONCLUSIONS: Mechanical and chemical retentions contribute to resin adhesion to glass ceramic. Universal adhesive seems to not function in the same manner as a silane coupling agent.

Biodegradation of all-in-one self-etch adhesive systems at the resin-dentin interface.

This study evaluated the effects of two exogenous enzymes on the resin-dentin interface. Collagenase (Col) and acetylcholinesterase (Ach) were used to simulate salivary enzymes and accelerate the aging process of the bonding interfaces. Four adhesives, Adper Single Bond 2 (SB), Clearfil SE Bond (SE), Clearfil tri-S Bond (S3) and G-Bond (G), were bonded to the dentin surfaces. After storage in water with collagenase or acetylcholinesterase, the specimens were examined using a microtensile bond strength test (MTBS). Nanoleakage patterns were observed with a scanning electron microscope (SEM). The MTBS results demonstrated significantly lower bond strengths in the groups stored with either enzyme than in water. SB exhibited severe degradation after exposure to collagenase, while G showed severe degradation after exposure to acetylcholinesterase. All of the self-etch systems (SE, S3 and G) exhibited water-tree patterns within the adhesive layer when immersed in water for three months. The etch-and-rinse system (SB) showed nanoleakage within the hybrid layer and the adhesive.

Resin-dentin bond strength as related to different surface preparation methods.

OBJECTIVE: To determine the microtensile bond strength and micromorphological structures on bonding of two adhesives (OptiBond FL and Clearfil SE Bond) to dentin surfaces ground with different preparation methods. METHODS: Extracted human molars were ground flat to expose mid-coronal occlusal dentin surface with one of six preparation methods--P120 grit SiC paper, P400 grit SiC paper, P1200 grit SiC paper, medium grit diamond bur, fine grit diamond bur, and carbide bur. Each of the adhesives was used to bond resin-based composite to the dentin surface. Dumbbell-shaped specimens were fabricated and microtensile bond strengths were determined. The subsequent debond pathway and micromorphological structures of representative dentin surfaces were examined under scanning electron microscopy. ANOVA and survival analyses were performed both assuming independence from and accommodating for within-tooth correlation between specimens. RESULTS: By ignoring the correlations between specimens, statistical analyses revealed no surface preparation effect on microtensile bond strength for each adhesive system. However, effects of surface preparation method on dentin adhesion of both adhesives were detected when accommodating for any within-tooth specimen correlations. Overall, carbide bur group showed the lowest bond strength for both OptiBond FL and Clearfil SE Bond. Dentin surfaces ground with diamond burs tended to present more compact smear layer than those ground with SiC papers and, subsequently, produced an effect on resin-dentin bond strengths. CONCLUSIONS: The dentin surface preparation method affects smear layer characteristics and dentin surface topography and, therefore affects resin-dentin bond strength. Smear layer denseness, more so than thickness, may compromise bonding efficacy of adhesives, especially of the self-etch systems.

Effects of saliva contamination on dentin bond strength using all-in-one adhesives.

PURPOSE: To evaluate the effects of saliva contamination on microtensile bond strengths of all-in-one adhesives to dentin. MATERIALS AND METHODS: Flat superficial occlusal dentin surfaces of extracted human molars were used and randomly divided into 2 groups depending on two all-in-one adhesives: One-Up Bond F Plus (Tokuyama Dental) and Adper Prompt L-Pop (3M ESPE). For each adhesive, the teeth were allocated to 7 subgroups in which one group was bonded without contamination with saliva, serving as a control. The other groups, either before or after the polymerization of adhesives, were contaminated with saliva and dried; contaminated, dried, and adhesives re-applied; contaminated, rinsed, and the adhesives re-applied. Resin composite was then placed on the treated dentin surfaces. After 24 h storage in distilled water at 37 degrees C, the teeth were sectioned perpendicular to the adhesive interface in x and y directions, obtaining multiple beam-shaped specimens with a cross-sectional area of approximately 1.0 mm2. Specimens were stressed in tension at 1 mm/min until rupture of the bond. Data were analyzed using one-way ANOVA and the Games-Howell test. RESULTS: For both all-in-one adhesives, saliva-contaminated groups showed lower bond strengths than the controls. Re-application of the adhesives after drying or rinsing the saliva off restored the dentin bond strengths to the control levels. CONCLUSION: Saliva contamination reduced the dentin bond strengths of all-in-one adhesives. Supplementary application of the adhesive after cleaning the saliva from the dentin surface is an empirical recommendation for restoring bond strength.

Shear bond strength of tooth-colored indirect restorations bonded to mid-coronal and cervical dentin.

To investigate the bonding of tooth-colored indirect restorations to cervical dentin, shear bond strengths of bonded resin inlays to cervical dentin and mid-coronal dentin were investigated and compared. Indirectly fabricated composite inlays (Estenia) were cemented with a dual-cured resin cement (Panavia Fluoro Cement II) to either cervical or mid-coronal dentin. Resin cement was cured with or without light irradiation for 20 seconds. After 24-hour or one-week storage, the bonded inlays were subjected to a micro-shear bond test. The light-cure method showed significantly higher bond strengths to both dentin regions compared with the self-cure method. Further, significant improvement in bonding after one-week storage was found in the case of light-cure method rather than the self-cure method. Although the cervical dentin tended to show lower bond strength than mid-coronal dentin, significant difference between the two dentin regions was only found when the resin cement was light-cured and stored for only one day.

Bonding of resin to artificially carious dentin.

PURPOSE: To evaluate the bond strength of adhesive resins to artificially carious dentin specimens which were previously exposed to an acid buffer solution for various periods. MATERIALS AND METHODS: Flat dentin disks were obtained from superficial occlusal dentin of extracted human third molars and polished with wet silicon carbide paper. Dentin disks were immersed in acid buffer solution for different periods to create the demineralized dentin layer. The first group of demineralized specimens was used for the evaluation of demineralization depth under SEM and the second group was used for the bond strength measurement. Shear bond strengths mediated by three dentin adhesives (Clearfil SE Bond, OptiBond Solo Plus Total-Etch, and OptiBond Solo Plus Self-Etch) were examined. A 0.75-mm-diameter area of dentin was bonded according to the manufacturers' instructions before placing a 0.5-mm-high resin composite cylinder. The bonds were stressed in shear at a crosshead speed of 1 mm/min. All data were analyzed using ANOVA and LSD multiple comparison test. RESULTS: Depth of demineralization increased with the prolongation of demineralizing time. After dentin specimens were demineralized for up to 24 h, bond strengths of the self-etching adhesives were significantly higher than those of the total-etch adhesive. However, for longer demineralization periods, no statistical differences in bond strengths were observed. SEM photographs showed that resins cannot thoroughly infiltrate through the whole depth of the demineralized dentin layer. CONCLUSION: Bond strengths to demineralized, artificially carious dentin were affected by the depth of demineralization and adhesive resins used.

Monkey pulpal response to an MMA-based resin cement as adhesive luting for indirect restorations.

PURPOSE: The objective of this study was to evaluate the pulpal response to a newly-developed MMA resin cement (MultiBond, Tokuyama) when used for adhesively luting composite resin inlays. MATERIALS AND METHODS: Cervical cavities were prepared in monkey teeth. The teeth were randomly divided into 3 groups. In the experimental group, a self-etching primer and a resin cement were applied to the cavities, and then hybrid composite inlays (Estenia, Kuraray) were inserted using freshly mixed resin cement. In the other groups, a zinc oxide/eugenol cement (Eugedain, Showa Yakuhin Kakou) or a glass-ionomer cement (Fuji II, GC) was used to fill the cavity. The teeth were then extracted after 3, 30, and 90 days, fixed in 10% buffered formalin solution, and prepared using routine histological techniques. Five-mum-thick sections were stained with hematoxylin and eosin, or Brown & Brenn gram stain for bacterial observation. Histopathological reactions in the pulp tissue and bacterial penetration along the cavity walls were assessed using a standardized score. RESULTS: No serious inflammatory reactions in the pulp, such as necrosis or abscess formation, were observed in any of the experimental periods, except for 1 case after 30 days, in which a pulpal exposure was suspected. Disarrangement of the odontoblast layer and deposition of reparative dentin were the major reactions observed in this specimen. No bacterial penetration along the cavity walls was detected. The monkey pulpal response and in vivo sealing ability of the MMA resin cement in combination with the self-etching primer was considered as good as that of the glass-ionomer cement. CONCLUSION: The new MMA resin cement showed acceptable biological compatibility to the monkey pulp when used to adhesively lute composite resin inlays.

Bond strengths of current adhesive systems on intact and ground enamel.

PURPOSE: The goal of this study was to compare the microshear bond strengths of current adhesive systems to intact and ground enamel surfaces. MATERIALS AND METHODS: Three commercially adhesive materials were examined: a two-step total-etching self-priming system (Single Bond, 3M ESPE, St. Paul, MN, USA), a two-step self-etching system (Clearfil SE Bond, Kuraray Co. Ltd., Osaka, Japan), and an all-in-one system (One-Up Bond F, Tokuyama Dental, Tokyo, Japan). The labial surfaces of extracted human incisors were used. For intact enamel surfaces, the teeth were polished with pumice. However, for the ground enamel, 0.5 mm deep, flat enamel surfaces at the midlabial aspect were ground with a no. 600 grit silicon carbide paper. Ground and intact enamel surfaces were bonded with one of three bonding systems and a resin composite and were subjected to a microshear bond test. RESULTS: The two self-etching systems demonstrated lower bond strengths than did the total-etching system on intact enamel (One-Up Bond F, 18.59 MPa; Clearfil SE Bond, 35.71 MPa; Single Bond, 47.20 MPa). No significant difference was found between the total-etching system and the two-step self-etching system on ground enamel (One-Up Bond F, 28.96 MPa; Clearfil SE Bond, 48.51 MPa; Single Bond, 51.07 MPa). Shear bond strengths on ground enamel were significantly higher than those on intact enamel except for the group that was bonded with the total-etching system. CONCLUSIONS: The two-step adhesives showed significantly higher bond strengths than did the one-step adhesive. When applying the total-etching system, no significant differences in bond strength were demonstrated between bonding to intact and to ground enamel.

The bond of resin to different dentin surface characteristics.

This study investigated the effects of dentin surface characteristics on bond strengths between resin and dentin. The shear bond strengths mediated by two dentin adhesive systems (Clearfil SE Bond and OptiBond Solo Plus) were evaluated. For each material, flat dentin surfaces prepared from human upper premolars were allocated to eight groups according to three characterizations; dentin location (occlusal or cervical), dentin depth (superficial or deep) and dentinal tubule orientation (perpendicular or parallel). A 0.75-mm diameter area of dentin was bonded according to each manufacturer's instructions before placing 0.5-mm high resin composite. The bonds were stressed in shear at a crosshead speed of 1 mm/minute. The mean bond strengths were compared using ANOVA and independent t-test. No statistically significant differences were found in shear bond strengths based on dentin location. Clearfil SE Bond presented higher bond strengths to deep dentin specimens bonded perpendicular to the tubules compared to those that were bonded parallel to the tubules. Whereas, the opposite results were found for deep dentin specimens bonded with OptiBond Solo Plus. In the case of superficial dentin, there were no differences between the two materials when bond strengths were compared among the different orientations of tubule. The results indicated that shear bond strengths may be affected by dentin depth, orientation of the tubule and the bonding material used, but not by location of the dentin.