Questionnaire survey on hands-on simulation training using a dental humanoid robot (SIMROID®).

INTRODUCTION: A dental humanoid robot, SIMROID®, is able to replicate the actions characteristic of human beings and enable training for communicating with patients and coping with unexpected situations. This study assessed user experiences via a survey questionnaire following hands-on training on the SIMROID®. MATERIALS AND METHODS: A total of 112 participants, consisting of 50 high school students who visited AUSD (Asahi University School of Dentistry) to participate in open campus events, 42 fourth-year students at AUSD and 20 dental students from Mexico State Autonomy University, University of Siena and Peking University took the survey. The participants observed the movements and reactions of a SIMROID® robot placed on a dental unit for approximately 20 min after which they completed a questionnaire survey. Both Japanese and English versions of the questionnaire were prepared for local and visiting foreign dental students. The questionnaire comprised 8 items, with a further two items for those undertaking dental training and an open comment field. RESULTS: All participants who observed the SIMROID® completed the questionnaire giving a 100% response rate. Generally, simulation training with SIMROID® was highly appreciated by all participants. The comprehensive evaluation score for SIMROID® was 4.56 ± 0.50 points for high school students, 4.05 ± 0.82 points for students at AUSD and 4.70 ± 0.47 points for foreign dental students, showing all participants had a very positive experience and impression of the SIMROID®. CONCLUSIONS: Therefore, simulation training using SIMROID® seems beneficial learning tool.

MDP-salts as an adhesion promoter with MDP-primers and self-adhesive resin cement for zirconia cementation.

PURPOSE: To evaluate the effect of zirconia priming with MDP-Salt before MDP containing primers and self-adhesive cement on the shear bond strength. MATERIALS AND METHODS: Fully sintered high translucent zirconia specimens (n = 120) were assigned into 2 groups (n = 60 each): Control (No Pretreatment) and Methacryloyloxydecyl dihydrogen phosphate salt (MDP-Salt) pretreated. Each group was divided into 3 subgroups (n = 20) according to cementation protocol: 1) MDP + Silane primer and conventional resin cement, 2) MDP+ Bisphenyl dimethacrylate (BPDM) primer and conventional resin cement, and 3) MDP containing self-adhesive resin cement. Shear bond strength (SBS) was measured after 10,000 thermocycling. Contact angle was measured for tested groups. Surface topography was assessed using a 3D confocal laser scanning microscope (CLSM). Weibull analysis was performed for SBS and one-way ANOVA for contact angle and surface topography measurements (α = 0.05). RESULTS: The use of MDP-Salt significantly improved the SBS (p < .05) for all tested subgroups. Self-adhesive cement showed an insignificant difference with MDP + Silane group for both groups (p > .05). MDP + BPDM showed a significantly lower characteristic strength compared to self-adhesive resin cement when both were pretreated with MDP-Salt. No difference between all tested groups in the surface topographic measurements while MDP-Salt showed the highest contact angle. CONCLUSION: MDP-Salt pretreatment can improve bonding performance between zirconia and MDP containing products.

Influence of 10-methacryloyloxydecyl dihydrogen phosphate (MDP) incorporated experimental cleaners on the bonding performance of saliva-contaminated zirconia ceramic.

OBJECTIVES: To assess the efficacy of experimental cleaners containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) on the saliva decontamination of ceramic and their influence in restoring zirconia's adherence to resin cement. MATERIALS AND METHODS: Four hundred sixty alumina-blasted zirconia specimens were categorized into saliva-contaminated and uncontaminated groups which were treated with ceramic primer (P), experimental cleaner 1 (C1), C1 followed by P (C1P), experimental cleaner 2 (C2), and C2 followed by P (C2P). Stainless-steel rods were then attached to the specimens using PanaviaV5 cement (Kuraray Noritake Dental; Tokyo, Japan). Tensile bond strength (TBS) test was performed after 24 h and 5000 thermocycling processes. X-ray photoelectron spectroscopy (XPS) analysis and contact angle measurement of the specimen were performed. The TBS data were analyzed by Weibull analysis and three-way ANOVA. Contact angle data were analyzed by two-way ANOVA (α = 0.05). RESULTS: C2P groups showed the highest TBS in all conditions among tested groups. Saliva contamination led to a significant reduction of TBS in primer- and cleaner-treated groups, with no significant impact on C2P. Adhesive failure was predominant in contaminated groups except with the C1P and C2P groups. XPS revealed that a nitrogen peak was observed on contaminated groups but not in primed groups. The contact angle was significantly affected by saliva contamination, the cleaners, and/or ceramic primer usage (p < 0.001). CONCLUSIONS: The MDP cleaner followed by the MDP primer protocol may overcome the effect of saliva contamination and improve the resin-ceramic bond strength. CLINICAL RELEVANCE: It is recommended to use a combination of MDP-containing cleaner 2 and ceramic primer as a chair-side chemical pretreatment for zirconia substrate with or without saliva contamination.

The effects of different silicatization and silanization protocols on the bond durability of resin cements to new high-translucent zirconia.

OBJECTIVE: The aim of this study was to assess the influence of different silicatization protocols with various silane treatment methods on the bond performance to high-translucent zirconia. MATERIALS AND METHODS: High-translucent zirconia specimens were assigned to five groups according to mechanical surface pretreatment: as-sintered (Con), 0.2 MPa alumina sandblasting (AB2), tribochemical silica coating (TSC), 0.2 and 0.4 MPa glass bead air abrasion (GB2) and (GB4). Each group was subjected to 4 different cementation protocols: Panavia SA Universal (SAU), Panavia SA plus (SAP), silane + SAP (S-SAP), and Universal adhesive + SAP (U-SAP). Tensile bond strength (TBS) was measured after 24 h and 10,000 thermocycling (TC). Surface topography, surface energy, and elemental composition of the abraded zirconia surface analyses were completed. TBS data was analyzed using the Weibull analysis method. Surface roughness and surface energy were compared by one-way ANOVA analysis of variance (α = 0.05). RESULTS: After 24 h, higher TBS was achieved with all cementation protocols in AB2 and TSC, also, in GB2 with all protocols except U-SAP, and in GB4 with SAU and S-SAP. After aging, GB4/S-SAP, GB2/S-SAP, AB2/U-SAP, and TSC/S-SAP showed the highest bond strength. GB groups showed the lowest surface roughness and highest surface energy. CONCLUSION: Glass bead abrasion achieved the durable bond strength to high-translucent zirconia using a separate silane coupling agent while altered surface chemistry, surface energy, and roughness without effect on morphology. CLINICAL RELEVANCE: Glass bead air abrasion is an alternative to alumina sandblasting and tribochemical silica coating and improves bond strength to high translucent zirconia.

Progression of non-carious cervical lesions: 3D morphological analysis.

OBJECTIVES: This longitudinal study aimed to investigate morphologically and quantitatively the progression of non-carious cervical lesions (NCCLs) using a confocal laser scanning microscope (CLSM) and replica models. MATERIALS AND METHODS: The samples examined comprised sets of replicas annually obtained from 83 lesions in 16 participants over 3 to 5 years. All lesions were visually categorized as wedge-shaped, saucer-shaped, or mixed-shaped lesions. CLSM images of the replicas were analyzed in terms of axial depth, occlusogingival width (height) in the buccolingual cross-section, and estimated volume using a custom code of the image analysis software to estimate the progression of the NCCLs over time. The morphological characteristics of the NCCLs were also objectively divided into three groups according to the depth to height ratio (D/H ratio). Fisher's exact test and the Cochran-Armitage trend test were used for statistical analysis. RESULTS: Saucer-shaped lesions progressed mainly in height, whereas wedge-shaped lesions increased both in height and depth. Annual progression in depth and volume significantly increased as the D/H ratio increased. More than half of the NCCLs with a small D/H ratio progressed 50 µm or more in height, whereas none of them progressed more than 50 µm in depth. Annual progression in depth significantly increased as the lesion depth at baseline increased. CONCLUSIONS: Progression patterns significantly differed between NCCLs of different shapes. Most NCCLs progressed slowly in depth regardless of their shape. Moreover, NCCLs may progress through active and inactive stages.

Effect of Air-Particle Abrasion Protocol and Primer on The Topography and Bond Strength of a High-Translucent Zirconia Ceramic.

PURPOSE: To evaluate effect of air-particle abrasion protocol and primer on surface topography and bond strength of resin cement to high-translucent zirconia ceramics. MATERIALS AND METHODS: Two hundred disk-shaped high-translucent zirconia specimens of 5Y-PSZ were prepared. The specimens were assigned to 5 groups in terms of particle type and air-particle abrasion pressure: (1) control, (2) alumina with 0.2 MPa-air pressure [AB-0.2], (3) alumina with 0.4 MPa-air pressure [AB-0.4], (4) glass beads with 0.2 MPa-air pressure [GB-0.2], and (5) glass beads with 0.4 MPa-air pressure [GB-0.4]. Two different primers 1% MDP (Experimental) and MDP-silane primer (Clearfil Ceramic Primer Plus) was also tested. Stainless steel rods were bonded to the 5Y-PSZ specimens with PANAVIA V5. For each group, the tensile bond strength (TBS) was measured after 24-hour water storage (n = 10) and after 5000 thermal-cycling (n = 10) at crosshead speed of 2 mm/min. The data were statistically analyzed using Weibull analysis. Surface roughness (Sa) was measured using a 3D-Laser Scanning Confocal Microscope (n = 5) and analyzed by t-test with Bonferroni correction. Surface topography using scanning electron microscopy (SEM) and surface elemental analysis using energy dispersion spectroscopy (EDX), and cross-section SEM at the interface with composite cement were also investigated. RESULTS: In MDP-silane groups, the highest TBS was observed in AB-0.4 after 24 hours and GB-0.4 after thermal-cycling (p < 0.05). In MDP groups, AB groups resulted in the significantly higher TBS than GB groups (p < 0.05). AB-0.4 group showed the highest Sa value compared to all groups (p < 0.005), meanwhile GB groups did not show different Sa compared to control (p > 0.005). CONCLUSION: Air-abrasion with different particle and blasting pressure can improve bonding to zirconia with proper primer selection. Particularly, glass beads abrasion followed by MDP-silane primer and alumina abrasion followed by MDP primer alone provided stable bond strength of resin cement to high-translucent zirconia after aging. High-translucent zirconia abraded with glass beads achieves a desirable bonding performance without creating surface microcracks which may hinder zirconia's mechanical properties.

The prevalence of non-carious cervical lesions (NCCLs) with or without erosive etiological factors among adults of different ages in Tokyo.

OBJECTIVES: To evaluate the prevalence of non-carious cervical lesions (NCCLs) on teeth with or without erosive etiological factors across a broad range of ages of Japanese adults. MATERIALS AND METHODS: The study sample consisted of a total of 1108 subjects aged 15 to 89 years in Tokyo, Japan. Two examiners evaluated NCCLs and dental erosion (DE) during a full-mouth examination. Subjects were asked to complete a self-administered daily diet, habits, and health condition questionnaire. Subjects who had frequent acid consumption or gastric reflux and at least one tooth with initial enamel wear were placed in the erosion present (EP) group, and the remainder of subjects were placed in the erosion not present (EN) group. Logistic regression analyses were carried out to identify etiological factors of NCCLs associated with DE. RESULTS: Overall prevalence of NCCLs was 60.2%; the prevalence increased with age. There were no statistical differences in the prevalence of NCCLs between the EP and EN groups, except for the 60-69 years group. Multiple logistic regression analysis showed the frequency of consumption of carbonated soft drinks, citrus juice, and acidic fruits such as oranges; tooth brushing pressure; and bruxism were associated with the presence of NCCLs. CONCLUSION: There were no statistical differences in the prevalence of NCCLs with or without erosive etiological factors except for the 60-69 years group. CLINICAL RELEVANCE: NCCL distribution increased with age, and erosive risk factors caused by change in dietary habits might affect the incidence of NCCLs for elders. TRIAL REGISTRATION: UMIN000041982.

Efficacy of Various Surface Treatments on the Bonding Performance of Saliva-contaminated Lithium-Disilicate Ceramics.

PURPOSE: To investigate the efficacy of different ceramic surface cleaning methods after saliva contamination on the resin bond strength to lithium disilicate ceramics. MATERIALS AND METHODS: 300 e.max CAD blocks (Ivoclar Vivadent) were polished with 600-grit silicon carbide paper and divided into five groups with or without human saliva contamination and according to the surface treatment performed (n = 10); control: no pretreatment; MP: Monobond Plus; PA+MP: 37% phosphoric acid (PA) followed by MP; HF+MP: 5% hydrofluoric acid (HF) followed by MP; MEP: Monobond Etch & Prime. The specimens were bonded with one of three resin cements: Variolink Esthetic DC (VE), Multilink Automix (MA) and Speed CEM (SC). After 24-h water storage, tensile bond strength (TBS) was measured. The ceramic surfaces after pretreatment were analyzed using x-ray photoelectron spectroscopy (XPS). RESULTS: XPS analysis showed similar elemental distributions between saliva contamination vs no saliva in PA, HF, and MEP. The TBSs were significantly influenced by surface treatments (p < 0.05). HF+MP and MEP showed statistically non-significantly different bond strengths to saliva-contaminated HF+MP and MEP, but were different from MP and saliva-contaminated MP. The TBSs after 24 h were significantly higher in HF+MP and MEP groups with VE. HF+MP and MEP did not show statistically significant differences among any groups with or without saliva contamination. CONCLUSION: Surface treatments with PA or HF followed by silane or by MEP alone were effective in removing saliva contamination and enhancing the resin bond strength.

Effects of Different Tooth Conditioners on the Bonding of Universal Self-etching Adhesive to Dentin.

PURPOSE: To investigate the effect of different etching products used prior to the application of universal self-etching adhesive on dentin bonding. MATERIALS AND METHODS: The etching products Multi Etchant (ME), Enamel Conditioner (EC), and K-etchant GEL (KE) were used as pre-treatments prior to the application of the one-bottle self-etching adhesive Adhese Universal (AU). Ground human dentin surfaces were randomly divided into four treatment groups: 1. control (CT; AU without con-ditioner); 2. ME; 3. EC; 4. KE. Microtensile bond strength (µTBS) tests with a thermocycling challenge (0-TC or 10,000-TC) were carried out and the morphological attributes of the adhesive-dentin interface were observed after an acid-base challenge using SEM to observe the acid-base resistant zone (ABRZ). RESULTS: The KE group had a statistically significantly lower µTBS than did the ME and EC groups at 0-TC, and than the CT, ME, and EC groups at 10,000-TC (p < 0.05). An ABRZ was observed in all groups but had partially disappeared in KE. A funnel-shaped area of erosion was also observed at the junction of the dentin and bonding layer in the CT, ME, and EC groups, while the hybrid layer was thicker in the KE group with no evidence of erosion. CONCLUSION: The application of ME or EC did not reduce the microtensile bond strength and resulted in ABRZ formation, while the ABRZ was partially reduced in the KE group.

Influence of Ambient Air and Different Surface Treatments on the Bonding Performance of a CAD/CAM Composite Block.

PURPOSE: To evaluate the bond strengths of time elapsed after sandblasting with alumina particles on a CAD/CAM composite block treated with different surface conditioning methods. MATERIALS AND METHODS: A CAD/CAM composite block (CCB) was cut into 72 slices of approximately 2 mm thickness. The CCB slices were divided into three groups according to sandblasting pressure (0.1 MPa, 0.2 MPa, or untreated), and then divided into two subgroups according to the time elapsed after sandblasting: same-day or one-week dry storage under controlled laboratory conditions before cementation. Surface roughness was observed by confocal laser microscopy (CLSM) (n = 20); then the wettability of the CCB surfaces was examined using a contact angle (CA) measuring device on a droplet of deionized water (n = 12). Next, CCB slices were divided into three subgroups according to the surface treatment: Clearfil Ceramic Primer (CP), Clearfil Universal Bond (UB), or a mixture of Clearfil Porcelain Bond Activator and Clearfil tri-S Bond ND Quick (NDP). All CCB slices were then cemented with Panavia V5 and stored at 37°C in distilled water for 24 h and cut into sticks (n = 10). The sticks were subjected to microtensile bond strength (µTBS) testing, and failure mode analysis was performed using scanning electron microscopy. The µTBS results were subjected to 3-way and 2-way ANOVA (α = 0.05). RESULTS: All groups showed a statistically significant increase in wettability accompanied by decreased µTBS after one week; however, the UB group exhibited stable performance after one week. CONCLUSION: The time elapsed after sandblasting with alumina particles affects the bond strength, but it had no significant effect on the UB group.

Bonding Efficacy of 4-META/MMA-TBB Resin to Surface-treated Highly Translucent Dental Zirconia.

PURPOSE: To evaluate the bonding efficacy of 4-META/MMA-TBB resin to highly translucent zirconia subjected to various surface treatments. MATERIALS AND METHODS: Highly translucent zirconia specimens (Zpex Smile, Tosoh; 11.5 mm diameter, 5.0 mm thick) were mechanically pre-treated to improve micromechanical interlocking either by sandblasting with 50-µm Al2O3 particles (Kulzer Japan) or subjecting the specimens to a low-pressure plasma treatment (PM100, Yamato), or evaluated using the as-sintered surfaces as controls. Next, specimens from each condition were primed with an MDP-containing primer (PZ Primer, Sun Medical), while some remained unprimed. All specimens were bonded to stainless rods using 4-META/MMA-TBB resin (Super-Bond, Sun Medical). The specimens were stored in ultrapure water at 37°C for 24 h, after which a portion were subjected to 10,000 thermocycles. For all specimens (n=10/group) the tensile bond strength (TBS) was determined with a universal testing machine. The measured values were statistically analyzed using Weibull analysis. Fractographic analysis was performed using a light microscope and an SEM. RESULTS: After aging, Weibull analysis revealed significantly lower bond strengths for both as-sintered and plasma-treated zirconia without a primer treatment. The fractographic analysis showed that these two conditions resulted in a higher frequency of adhesive failure. CONCLUSION: Chemical pre-treatment with an MDP-containing primer improved bonding efficacy of 4-META/MMA-TBB resin to highly translucent zirconia. In addition, Al2O3 sandblasting resulted in durable bonding of 4-META/MMA-TBB resin to highly translucent zirconia, regardless of chemical pre-treatment.

Effects of Selective Phosphoric Acid Etching on Enamel Using "No-wait" Self-etching Adhesives.

PURPOSE: To evaluate the effect of selective phosphoric acid etching on enamel using "no-wait" self-etching adhesives. MATERIALS AND METHODS: Clearfil Universal Bond Quick (UBQ, Kuraray Noritake) or G-Premio BOND (GPB, GC) was applied to ground human enamel surfaces. The adhesives were used in 3 modes: no-waiting self-etching mode (UBQ-0 or GPB-0), 10-s self-etching mode (UBQ-10 or GPB-10), and the selective-etch mode with phosphoric acid etching (UBQ-PA or GPB-PA). After an acid-base challenge, the morphological attributes of the interface were examined using scanning electron microscopy (SEM) to characterize the acid-base resistant zone (ABRZ). Microshear bond strength (µSBS) testing to enamel and ultimate tensile strength (UTS) of the adhesive resin were carried out. RESULTS: ABRZ formation was confirmed in all groups. UBQ-PA and GPB-PA created thicker ABRZ with no funnel-shaped erosion beneath the adhesive-enamel interface. µSBS of UBQ-PA was significantly higher than UBQ-0 and UBQ-10 (p < 0.05). However, there were no statistically signficant differences in µSBS among GPB-0, GPB-10, and GPB-PA. For the UTS, UBQ was significantly higher than GPB. CONCLUSION: Selective phosphoric acid etching created a stable adhesive-enamel interface. The no-waiting self-etching concept adhesive led to a thinner ABRZ. The results of µSBS suggest that phosphoric acid etching effects on enamel are material dependent.

Evaluation of MDP and NaF in Two-step Self-etch Adhesives on Enamel Microshear Bond Strength and Morphology of the Adhesive-Enamel Interface.

PURPOSE: To evaluate the roles of MDP and NaF in the bonding resin of a two-step self-etch adhesive (2-SEA) on enamel bonding performance. MATERIALS AND METHODS: The experimental 2-SEAs were composed of an MDP-containing self-etching primer and four different bonding resins which were MDP- and NaF-free (00), MDP-containing and NaF-free (M0), MDP-free and NaF-containing (0F), and MDP- and NaF-containing (MF) adhesives. Microshear bond strength (µSBS) to enamel and ultimate tensile strength (UTS) of the adhesive resin were determined. The morphological characteristics of the adhesive-enamel interface after acid-base challenge were observed using SEM to evaluate the acid-base resistant zone (ABRZ). RESULTS: No decrease in µSBS was observed even after thermocycling (TC) in 00, 0F and MF. However, the µSBS of M0 significantly decreased after TC. The UTS of M0 significantly decreased after 1- and 180-day storage in water. SEM observations indicated that ABRZ was present in all groups. However, formation of erosion beneath the ABRZ was observed in M0 and 00, whereas formation of a slope without erosion was observed at the bottom of the ABRZ in MF. CONCLUSION: In the experimental 2-SEAs, the addition of MDP alone to the adhesive resin did not contribute to an improvement in enamel bonding durability and interfacial morphology, whereas the addition of NaF in the adhesive resin demonstrated an enhancement of the bonding durability and improvement of acid resistance at the bonded interface.

Effect of Different Surface Treatments on the Tensile Bond Strength to Lithium Disilicate Glass Ceramics.

PURPOSE: To evaluate the influence of different surface treatments of lithium disilicate glass ceramics on the bonding efficacy of three luting composites. MATERIALS AND METHODS: A total of 450 blocks of e.max CAD (Ivoclar Vivadent) ground with 600-grit silicon carbide paper were prepared and divided into three groups (n = 150) according to the composite cements used: Variolink Esthetic DC (VE), Multilink Automix (MA), and SpeedCEM (SC). Each group was further divided into five subgroups (n = 10) according to the surface treatment performed: no treatment (control), Monobond Plus (MP), 37% phosphoric acid and Monobond Plus (PA), < 5% hydrofluoric acid and Monobond Plus (HF), and Monobond Etch & Prime (ME). All treated ceramic specimens were bonded with three composite cements and light cured. After 24-h water storage and 5000 or 10,000 thermocycles, tensile bond strength (TBS) was measured. The specimens underwent failure mode analysis. The results were statistically analyzed using two-way ANOVA and t-tests with Bonferroni correction. RESULTS: The TBSs were significantly influenced by surface treatments (p < 0.05). There were no significant differences in HF and ME among most of the groups. Furthermore, ME showed the highest bond strength with MA after 10,000 thermocycling. Most specimens of the ME groups exhibited cohesive failures, whereas a combination of adhesive failures and mixed failures were observed in control, MP, PA, and HF groups. CONCLUSION: In the surface treatment of lithium disilicate glass ceramics, Monobond Etch & Prime was found to be a possible substitution for the combination of hydrofluoric acid and Monobond Plus.

Erosive Tooth Wear Among Different Tooth Types and Surfaces in Japanese Adults 15 to 89 Years Old.

PURPOSE: To evaluate the prevalence of erosive tooth wear on buccal, incisal/occlusal and palatal/lingual surfaces in a wide age range of Japanese adults. MATERIALS AND METHODS: The study included a total of 1108 adults aged 15 to 89 years in Tokyo, Japan. The subjects were asked to complete a self-administered nutrition-related questionnaire. Two examiners evaluated tooth wear on the buccal, occlusal/incisal and palatal/lingual surfaces in a full-mouth recording, using a modified Smith and Knight tooth-wear index. Subjects who frequently consumed acidic beverages or food, or had gastric reflux and at least one tooth with an initial enamel smooth-surface wear facet were placed in an erosion-positive group, and the rest of subjects were placed in the erosion-negative group. RESULTS: 26.1% of the participants were placed in the erosion-positive group. For buccal surfaces, advanced wear progression was predominantly observed on maxillary and mandibular anterior teeth, especially in the youngest age group (15-39 years). On incisal/occlusal surfaces, early dentin exposure was observed in the middle age group (40-49 years) in the erosion-positive group. For palatal/lingual surfaces, wear progression was mainly observed on maxillary anterior teeth among 30- to 39-year olds and 50- to 59-year-old in the erosion-positive group, but that prevalence was lower than for the other tooth surfaces. CONCLUSIONS: For all age groups of Japanese adults, the prevalence of erosive tooth wear depended on tooth types and surfaces.

Adsorption behavior of methacryloyloxydecyl dihydrogen phosphate on an apatite surface at neutral pH.

This study aimed to quantify the adsorption affinity of neutralized 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP-N) toward hydroxyapatite (HA) and dicalcium phosphate dihydrate (DCPD) at pH 7.0 by employing the Langmuir isotherm model. Furthermore, the effects of inorganic phosphate (Pi) and fluoride (F(-) ) ions on the adsorption of 10-MDP-N onto HA and DCPD were examined. Fixed amounts of HA and DCPD powders were suspended in different concentrations of 10-MDP-N solutions and were incubated for 18 h. Equilibrated concentrations of 10-MDP-N were measured by spectrophotometry and the adsorption affinity was estimated using the Langmuir model. Moreover, the adsorption was examined by zeta-potential analysis. The results indicated that significant Langmuir correlation was noted in both substrates, along with an increasing negative zeta-potential; however, in DCPD the correlation was less strong. The addition of 1.0 mM Pi slightly delayed the adsorption of 10-MDP-N onto both substrates, whereas 3.0 mM Pi drastically delayed adsorption onto HA but completely inhibited adsorption onto DCPD. Up to 50 ppm, F(-) enhanced the adsorption onto HA, and the adsorption plateaued at higher concentrations of F(-) , whereas no obvious influence of F(-) on the adsorption onto DCPD was noted.

Morphological Evaluation of the Adhesive/Enamel interfaces of Two-step Self-etching Adhesives and Multimode One-bottle Self-etching Adhesives.

PURPOSE: To evaluate the acid-base resistant zone (ABRZ) at the adhesive/enamel interface of self-etching adhesives with or without prior phosphoric acid etching. MATERIALS AND METHODS: Four adhesives were used in 8 groups: Clearfil SE Bond (SEB), Optibond XTR (XTR), Scotchbond Universal Adhesive (SBU), and Clearfil BOND SE ONE (ONE) without prior phosphoric-acid etching, and each adhesive with phosphoric acid etching for 10 s (P-SEB, P-XTR, P-SBU and P-ONE, respectively). After application of self-etching adhesives on ground enamel surfaces of human teeth, a flowable composite was placed. For observation of the acid-base resistant zone (ABRZ), the bonded interface was exposed to demineralizing solution (pH 4.5) for 4.5 h, followed by 5% NaOCl with ultrasonication for 20 min. After the acid-base challenge, morphological attributes of the interface were observed using SEM. RESULTS: ABRZ formation was confirmed in all groups. The funnel-shaped erosion beneath the interface was present in SBU and ONE, where nearly 10 to 15 µm of enamel was dissolved. With phosphoric acid etching, the ABRZs were obviously thicker compared with no phosphoric acid etching. CONCLUSION: Enamel beneath the bonding interface was more susceptible to acid dissolution in SBU and ONE. In the case of the one-bottle self-etching adhesives and universal adhesives that intrinsically have higher pH values, enamel etching should be recommended to improve the interfacial quality.

Nanoleakage in Hybrid Layer and Acid-Base Resistant Zone at the Adhesive/Dentin Interface.

The aim of interfacial nanoleakage evaluation is to gain a better understanding of degradation of the adhesive-dentin interface. The acid-base resistant zone (ABRZ) is recognized at the bonded interface under the hybrid layer (HL) in self-etch adhesive systems after an acid-base challenge. The purpose of this study was to evaluate nanoleakage in HL and ABRZ using three self-etch adhesives; Clearfil SE Bond (SEB), Clearfil SE One (SEO), and G-Bond Plus (GBP). One of the three adhesives was applied on the ground dentin surface and light cured. The specimens were longitudinally divided into two halves. One half remained as the control group. The others were immersed in ammoniacal silver nitrate solution, followed by photo developing solution under fluorescent light. Following this, the specimens were subjected to acid-base challenges with an artificial demineralization solution (pH4.5) and sodium hypochlorite, and prepared in accordance with common procedures for transmission electron microscopy (TEM) examination. The TEM images revealed silver depositions in HL and ABRZ due to nanoleakage in all the adhesives; however, the extent of nanoleakage was material dependent. Funnel-shaped erosion beneath the ABRZ was observed only in the all-in-one adhesive systems; SEO and GBP, but not in the two-step self-etch adhesive system; SEB.

Influence of different tooth etchants on bur-cut and uncut enamel.

This study aimed to evaluate the effect of pre-etching for two-step self-etch adhesive bonding to bur-cut and uncut enamel. Bur-cut and uncut enamel surfaces were assigned to surface treatments of no etchant (CT), Enamel Conditioner (EC; Shofu, Kyoto, Japan), or K-etchant syringe (KE; Kuraray Noritake Dental, Tokyo, Japan). The bonded samples were thermal cycled and evaluated by microshear bond strength (µSBS). The adhesive interface after acid-base challenge and the conditioned enamel surfaces were morphologically analyzed using scanning electron microscopy (SEM). For bur-cut enamel, EC and KE pre-etching significantly improved µSBS. For uncut enamel, KE showed higher µSBS than EC. SEM observation revealed that only KE removed the prismless layer of the uncut enamel surface. EC could improve enamel bonding and appears to be a substitute for phosphoric acid, especially for bur-cut enamel. However, uncut enamel could not be effectively conditioned by EC with a lower bond strength than KE.

Resin Cement/Enamel Interface: A Morphological Evaluation of the Acid-Base Resistant Zone, Enamel Etching Pattern, and Effect of Thermocycling on the Microshear Bond Strength.

PURPOSE: To evaluate the effects of etching mode (self-etch and etch-and-rinse) on acid-base resistant zone (ABRZ) formation at the resin cement/enamel interface and enamel etching pattern, as well as the effects of thermocycling (0, 5000, and 10,000 cycles) on the enamel microshear bond strength (µSBS) mediated by dual-cure resin cements (DCRC). MATERIALS AND METHODS: Two DCRC were used in 4 groups: Panavia V5 in self-etch (V5NE) and etch-and-rinse mode (V5E); and Estecem II in self-etch (ENE) and etch-and-rinse mode (EE). For ABRZ observation, the bonded interface was subjected to a demineralizing solution. The morphological attributes of the interface and etching patterns were observed using FE-SEM. For µ-SBS, cylinders with a 0.79-mm internal diameter and 0.5-mm height were made with DCRC and tested in shear after 0, 5000, and 10,000 thermal cycles (TC) (5°C and 55°C) (n = 10). RESULTS: The formation of an enamel ABRZ was observed in all groups with different morphological features between self-etch and etch-and-rinse groups. A funnel-shaped erosion beneath the interface was present using V5NE and ENE modes where enamel was dissolved, while ABRZ formation was confirmed and no funnel-shaped erosion was noticed using V5E and EE. No significant differences in µSBS were observed between resin cements. However, significantly lower µSBSs were recorded when the self-etching mode was used. Thermocycling resulted in a significant reduction in µSBS for all groups. CONCLUSION: Selective enamel etching should be recommended to improve the interfacial quality when dual-cure resin luting cements are used.