Assessment of the Efficacy and Bond Strength of Different Dentin-bonding Agents with Adhesives on Primary Teeth: An In Vitro Study.

AIM: The purpose of this study was to evaluate the effectiveness and strength of three various dentin-bonding agents used with adhesives on primary teeth. MATERIALS AND METHODS: The study used 80 recently extracted, healthy human maxillary anterior primary teeth that had undergone physiologic resorption, or over-retention. Teeth were cut to expose a flat dentin surface at a depth of 1.5 mm. All samples were divided into four groups (20 samples in each group) as follows: Group I-Control group, Group II-Primary teeth bonding with 6th-generation bonding agent, Group III-Primary teeth bonding with 7th-generation bonding agent, Group IV-Primary teeth bonding with 8th-generation bonding agent. All of the samples' dentinal surfaces were covered with composite resin using a Teflon mold after adhesive had been applied. A universal testing machine (INSTRON) was used to assess the shear bond strength. Data were collected and statistically analyzed. RESULTS: The maximum mean shear bond strength was found in 8th-generation bonding agent (30.76 ± 0.16), followed by 7th-generation bonding agent (26.08 ± 0.21), 6th-generation bonding agent (25.32 ± 0.06), and control group (6.18 ± 0.09). Statistically significant difference was found between the three different bonding agents (p < 0.001). CONCLUSION: On conclusion, the 8th-generation bonding agent demonstrated a greater shear bond strength to dentin than the 7th and 6th-generation bonding agent. CLINICAL SIGNIFICANCE: The emergence of different bonding techniques to the market improves the durability and quality of restorations. An effective bonding to the tooth would also reduce bacterial penetration, marginal microleakage, possibility of pulpal inflammation preserve tooth structure, and postoperative sensitivity by allowing less cavity preparation. How to cite this article: Alqarni AS, Al Ghwainem A. Assessment of the Efficacy and Bond Strength of Different Dentin-bonding Agents with Adhesives on Primary Teeth: An In Vitro Study. J Contemp Dent Pract 2024;25(4):342-345.

Assessment of physical properties of bioactive glass-modified universal multimode adhesive and its bonding potential to artificially induced caries affected dentin.

BACKGROUND: To evaluate the physical properties of bioactive glass-modified universal multimode adhesive and its micro-tensile bond strength (µTBS) to artificially induced caries-affected dentin. METHODS: All bond universal adhesive was used in the study. Specimens were divided into 2 main groups: control unmodified adhesive and 5 wt% BAG modified adhesive. The degree of conversion, pH, bioactivity, and viscosity of the adhesives were tested with n = 5 for each test. Micro-tensile bond strength evaluation was done in etch & rinse (ER) and selective-etch (SE) modes, where 24 human molar teeth were used (n = 3), 12 teeth for immediate bond strength, and the other 12 were tested after 6 months of storage in simulated body fluid (SBF). RESULTS: No significant difference was found between the control and the 5wt% BAG groups regarding the degree of conversion (61.01 ± 0.43 and 60.44 ± 0.61 respectively) and the viscosity (109.77 ± 22.3 and 124.3 ± 9.92 respectively). The control group revealed significantly lower pH values than the 5wt% BAG group (3.16 ± 0.5 and 4.26 ± 0.09 respectively). Immediate bond strength results revealed that the 5wt% BAG in the ER mode had the highest bond strength followed by the control group in the ER mode (44.16 ± 7.53 and 44.00 ± 7.96 respectively). SE groups showed that the immediate strength of the 5wt% BAG group was higher than the control group (42.09 ± 6.02 and 39.29 ± 6.64 respectively). After 6 months of storage, bond strength results revealed a decrease in bond strength values for the control groups but not for the 5wt% BAG in both application modes. CONCLUSIONS: The incorporation of BAG (5wt%) improved the universal adhesive micro-tensile bond strength and bond durability for both adhesive application modes without affecting its degree of conversion or viscosity.

Adhesive Performance Assessment of Universal Adhesives and Universal Adhesive/Composite Cement Combinations.

PURPOSE: To investigate the bonding performance of three universal adhesives (UAs) to dentin and the effect of different curing modes and hydrofluoric-acid (HF) etching of lithium-disilicate glass-ceramic on the adhesive performance of two UA/composite cement (CC) combinations. MATERIALS AND METHODS: In the first project part, the immediate and aged (25k and 50k thermocycles) microtensile bond strength (µTBS) of the two light-curing UAs G2-Bond Universal (G2B; GC) and Scotchbond Universal Plus (SBUp; 3M Oral Care), and the self-curing UA Tokuyama Universal Bond II (TUBII; Tokuyama) to flat dentin was measured, when applied in both E&R and SE bonding mode using a split-tooth design (n = 10). The resultant adhesive-dentin interfaces were characterized using TEM. In the second project part, CAD/CAM composite blocks were luted to flat dentin with either Scotchbond Universal Plus/RelyX Universal (SBUp/RxU; 3M Oral Care) or Tokuyama Universal Bond II/Estecem II Plus (TUBII/ECIIp; Tokuyama Dental) using different curing modes (AA mode: auto-curing of both adhesive and cement; AL mode: auto-curing of adhesive and light-curing of cement), upon which their immediate and aged (25k and 50k thermocycles) µTBS was measured. In the third project part, the same UA/CC combinations were luted to CAD/CAM glass-ceramic to measure their immediate and aged (6-month water storage) shear bond strength (SBS). RESULTS: In E&R bonding mode, the performance of G2B, SBUp and TUBII was not significantly different in terms of µTBS, while G2B and SBUp significantly outperformed TUBII in SE bonding mode. No significant difference in µTBS was found between the SBUp/RxU and TUBII/ECIIp UA/CC combinations, regardless of bonding mode, aging time, or curing mode. The cement-curing mode did not significantly influence µTBS, while a significantly higher µTBS was recorded for the UA/CC combinations applied in E&R bonding mode. HF significantly improved the SBS of the UA/CC combinations to glass-ceramic. CONCLUSION: The self-curing adhesive performed better when applied in E&R than in SE bonding mode. The curing mode did not influence the adhesive performance of the composite cements, while an E&R bonding mode rendered more favorable adhesion in a self-curing luting protocol. When bonding to glass-ceramic, the adhesive performance of the universal adhesive/composite cement combinations benefited from HF etching.

Micro Tensile bond strength and microleakage assessment of total-etch and self-etch adhesive bonded to carious affected dentin disinfected with Chlorhexidine, Curcumin, and Malachite green.

AIMS AND OBJECTIVES: Assessment of micro tensile bond strength (microTBS) and micro-leakage scores of total-etch adhesive (TAE) and self-etch adhesive (SAE) bonded to carious affected dentin (CAD) sterilized using different cavity disinfectant (curcumin photosensitizer (CP) and malachite green (MG) and Chlorhexidine (CHX) in comparison to no disinfection (ND) control group. MATERIALS AND METHODS: One hundred and twenty human molars having International Caries Detection and Assessment System (ICDAS) scores of 4 and 5 were included. Visual inspection, dental explorer hardness testing, and caries detector solution using 5% basic Fuchsin dye solution was applied to dentin to identify the CAD surface. All the specimens were divided into four groups (n = 30) according to the cavity disinfectants used. Group A: 2% CHX, Group B: CP, Group C: MG, and Group D: ND. Each group was further divided into two subgroups (n = 15) based on the adhesion protocol. Groups A1, B1, C1, and D1 were held using TEA, and groups A2, B2, C2, and D2 were adhered using SEA system. The composite material was then built in 2 mm increments and then cured with light. MicroTBS and failure mode assessment using a universal testing machine (UTM) and stereomicroscope at a 40X magnification was performed on 10 samples from each subgroup. The microleakage assessment was performed using a dye penetration test on five samples from each group. ANOVA and Tukey post-hoc tests were used to compare means and standard deviation (SD) of bond strength and microleakage (p < 0.05). RESULTS The maximum microTBS was displayed by A1= CHX and TEA (13.28± 1.01 MPa). The lowest bond scores were demonstrated by C2= MG and SEA (5.98±0.44 MPa). The highest micro-leakage was exhibited by C1= MG and TEA (58.32 ± 2.11 nm). Whereas, the lowest micro-leakage values were displayed by A2= CHX and SEA (24.34± 1.11 nm). CONCLUSION: Chlorohexidiene displayed better bond strength and the lowest microleakage scores with Total-etch adhesive and Self-etch adhesives when used as a cavity disinfectant. Total-etch adhesives performed better in terms of microTBS scores whereas self-etch adhesives displayed superior seal ability within the same disinfectant group.

Mechanical characterization and adhesive properties of a dental adhesive modified with a polymer antibiotic conjugate.

This study is a follow up investigation on recent work by our group demonstrating synthesis, release and strong antibacterial character of resins modified with penicillin V (PV)-based polymer-antibiotic conjugates (PACs). Here, we aimed to evaluate the mechanical, bonding, and other relevant biomedical properties of a commercial adhesive resin modified with PV-PAC. Single Bond Plus (SB+) was modified with PAC containing 1.8 wt% conjugated PV. Adhesive resins were bonded to dentin from extracted human molars and restorative resin added. Beams of cross-sectional area of 0.9 ± 0.1 mm (Kutsch and Young, 2011) (n = 20) were obtained from the molars and tested for micro-tensile bond strength (µTBS) at 24 h and 4 months. For cohesive strength, hourglass beams (10 × 2 × 1 mm; n = 10) were assessed for ultimate tensile strength (UTS), beam-shaped specimens (25x2x2 mm; n = 10) evaluated for flexural strength and modulus (FS/FM) via three-point bending, and cylindrical specimens (3 × 2 mm; n = 10) assessed for ultimate compressive strength (UCS). For surface micro-hardness (MH), cylindrical specimens (3 × 2 mm; n = 6) were assessed before and after an EtOH challenge. The degree of conversion (DC) (5 × 1 mm; n = 6) was determined based on changes in absorbance ratio between peaks at ∼1637 cm-1 and ∼1608 cm-1 before and after curing of adhesive resins using attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy. To monitor water uptake and diffusion kinetics over a 28-day period, specimens (5 × 1mm) were desiccated, weighed and stored in deionized water. Control and PV-PAC modified adhesive resins demonstrated similar µTBS at 24 h and 4 months; both showing decrease in values after 4 months (p = 0.001 and 0.004). No significant differences between adhesive resins were shown in UTS, FS/FM or UCS (p<0.05). MH of PV-PAC adhesive resin was significantly reduced relative to the control (p<0.001). The DC values of the adhesive resins were not significantly different. While sorption and solubility were no different between materials, the diffusion coefficient of PV-PAC modified adhesive resin was higher than the control (p<0.001). We conclude that incorporation of PV-PAC with 1.8 wt% PV into an adhesive resin does not adversely affect its mechanical, bonding, and physical properties, thus providing a promising option for materials with long-term antibacterial character and on-demand release.

Clinical and OCT assessment of application modes of a universal adhesive in a 12-month RCT.

OBJECTIVES: To evaluate a universal adhesive clinically using FDI criteria and by optical coherence tomography (OCT). METHODS: In 50 patients, three or four non-carious cervical lesions (NCCL) were restored with composite (Venus® Diamond Flow, Kulzer) using iBond® Universal (iBU, Kulzer) applied in self-etch (iBU-SE, n = 50), selective-enamel-etch (iBU-SEE, n = 29) or etch-and-rinse mode (iBU-ER, n = 50) and the reference OptiBond™ FL (OFL, Kerr, n = 50). Restorations were imaged by SD-OCT. The weighted mean length of interfacial adhesive defects (AD, %) was quantified per restoration immediately after placement (t0), simultaneously with clinical assessment (FDI criteria) after 14 days (t1), 6 (t2) and 12 months (t3). Data were statistically analyzed (McNemar-/Wilcoxon-/Mann-Whitney-U test (α = 0.05), Kaplan-Meier survival curves). RESULTS: After 12 months, cumulative failure rates were lower with iBU-SE (0.0%; p = 0.016), iBU-SEE (0.0%; p = 0.125), and iBU-ER (2.1%; p = 0.070; loss t3) compared to OFL (16.7%; losses t2, t3). Generally, marginal adaptation decreased (pi < 0.001) and marginal staining increased (pi ≤ 0.031), without significant group differences (pi > 0.064). AD increased in all groups (pi < 0.001). At enamel, AD appeared more extended with iBU-SE vs. iBU-SEE (t2-t3; pi ≤ 0.005), iBU-ER (t1-t3; pi ≤ 0.051) and OFL (t0-t3; pi ≤ 0.018). At dentin/cement iBU generally caused fewer defects than OFL (t1-t3; pi ≤ 0.010) and with SE vs. ER (t2-t3; pi = 0.010). CONCLUSIONS: In NCCLs, iBU generally provides a more durable bond than OFL. Recommended mode is SEE. Clinic and OCT provided comparable results. OCT has higher statistical power, shows group differences earlier and specifically for the different hard tooth tissues. CLINICAL SIGNIFICANCE: The universal adhesive iBU was superior against the reference OFL in NCCLs. It can be recommended with SEE. Evaluation of interfacial adhesive defects by OCT seems to allow early prediction of adhesives' clinical performance.

Physicochemical and microbiological assessment of a dental adhesive doped with cashew nut shell liquid.

To evaluate i) the inhibitory and bactericidal activity of cashew nut shell liquid (CNSL) and its isolated compounds (anacardic acid and cardol) against oral bacteria; ii) the biofilm formation inhibition, resin-dentin bond strength and physicochemical properties of a dental adhesive incorporated with these substances. The antibacterial effect of CNSL, anacardic acid, and cardol were assessed by determining the minimum inhibitory (MIC) and minimum bactericidal (MBC) concentrations. Effect in inhibiting biofilm formation of the adhesive incorporated with the substances (15 µg/ml) against a mixed-species biofilm of Streptococcus mutans and Candida Albicans and was determined by direct contact test. Additional Analysis included microtensile bond strength (µTBS) test, elastic modulus (EM), flexural strength (FS), degree of conversion (DC), water sorption (WS) and solubility (SL). The data were submitted to statistical analysis by one-way ANOVA and Tukey's test (p < 0.05). CNSL, anacardic acid and cardol showed antibacterial activity for all strains tested, with MIC and MBC values ranging from 3.12 to 25 µg/ml. There was no growth of colonies forming units in the adhesives incorporated with the substances. EM increased in the adhesive incorporated with anacardic acid, decreased after incorporation of cardol and it was not affected by incorporation of CNSL. The substances tested showed no effect in FS, DC, WS, SL and µTBS. In conclusion, the CNSL, anacardic acid and cardol showed antibacterial effects against oral bacteria and, the incorporation of substances did not reduce the performance of the adhesive.

In vitro assessment of ribose modified two-step etch-and-rinse dentine adhesive.

OBJECTIVE: Collagen fibrils aid in anchoring resin composite restorations to the dentine substrate. The aim of the study was to investigate effect of non-enzymatic glycation on bond strength and durability of demineralized dentine specimens in a modified two-step etch-and-rinse dentine adhesive. METHODS: Dentine surfaces were etched with 37% phosphoric acid, bonded with respective in vitro ethanol and acetone adhesives modified with (m/m, 0, 1%, 2% and 3% ribose), restored with restorative composite-resin, and sectioned into resin-dentine slabs and beams to be stored for 24h or 12 months in artificial saliva. Bond-strength testing was performed with bond failure analysis. Pentosidine assay was performed on demineralized ribose modified dentine specimens with HPLC sensitive fluorescent detection. The structural variations of ribose-modified dentine were analysed using TEM and human dental pulpal cells were used for cell viability. Three-point bending test of ribose-modified dentine beams were performed and depth of penetration of adhesives evaluated with micro-Raman spectroscopy. The MMP-2 and cathepsin K activities in ribose-treated dentine powder were also quantified using ELISA. Bond strength data was expressed using two-way ANOVA followed by Tukey's test. Paired T tests were used to analyse the specimens for pentosidine crosslinks. The modulus of elasticity and dentinal MMP-2 and cathepsin K concentrations was separately analyzed using one-way ANOVA. RESULTS: The incorporation of RB in the experimental two-step etch-and-rinse adhesive at 1% improved the adhesive bond strength without adversely affecting the degree of polymerisation. The newly developed adhesive increases the resistance of dentine collagen to degradation by inhibiting endogenous matrix metalloproteinases and cysteine cathepsins. The application of RB to acid-etched dentine helps maintain the mechanical properties. SIGNIFICANCE: The incorporation of 1%RB can be considered as a potential candidate stabilizing resin dentine bond.

Micro-CT assessment of comparative radiopacity of adhesive/composite materials in a cylindrical cavity.

This study was performed to evaluate the comparative radiopacity of adhesive/resin composite materials in cylindrical cavities using micro-computed X-ray tomography (µCT). The two-step self-etch adhesive systems, Clearfil SE Bond (SE) and FL-Bond II (FL), and flowable resin composites, Beautifil Flow F10 (BF) and Clearfil Majesty ES Flow High (MJ), were used. The radiopacity of bovine tooth structures and restorative materials was measured by µCT. In addition, cylindrical cavities prepared in bovine teeth were restored with the following adhesive/composite combinations: SE-BF, SE-MJ, FL-BF, and FL-MJ. The mean gray values of the composite restorations were calculated. The threshold values of the µCT images were evaluated using the Otsu's thresholding method. The current results show that the comparative radiopacity of the materials and tooth structure varied, which affected distinguishing the µCT images of the composite restorations in the cylindrical cavity. The proper combination of restorative materials should be considered when conducting in vitro µCT assessments of composite restorations.

The laboratory comparison of shear bond strength and microscopic assessment of failure modes for a glass-ionomer cement and dentin bonding systems combined with silver nanoparticles.

PURPOSE: More than half of the cavity restorations are replaced due to bacterial microleakage. A need for disinfection agents arises. Application of silver nanoparticles (AgNPs) may be beneficial, yet their impact on the adhesives' shear bond strength to dentin remains unknown. METHODS: The aim was to assess the shear bond strength to dentin of different dental materials combined with AgNPs. Failure modes were also examined using SEM/FIB, SEM/EDS and endodontic microscopes. RESULTS: The results showed no impact of AgNPs addition to dental materials in terms of shear bond strength to dentin. A change of the failure mode of the self-etch bonding system, Clearfil SE Bond, combined with AgNPs was observed. The new failure modes depended upon the order of application of the materials onto dentin. CONCLUSIONS: The microscopic evaluation of the samples showed the presence of AgNPs agglomerations gathered on the dentin's surface. AgNPs connection with self-etching dentin bonding system may have a serious clinical impact.

Short fibre-reinforced composite for extensive direct restorations: a laboratory and computational assessment.

OBJECTIVES: The objective of the study was to evaluate the effectiveness of a short fibre-reinforced composite (FRC) applied in combination with a conventional filler composite (CFC) on the fatigue resistance, fracture strength, failure mode and stress distribution, for restorations of premolars under two loading angles. MATERIAL AND METHODS: Thirty-two inferior premolars received extensive cavities with removal of the lingual cusp. Teeth were restored directly using 'FRC (EverX Posterior, GC) + CFC (G-aenial, GC)' or 'CFC only' and received two fatigue/fracture loadings at two different angles (0°/45°) (n = 8). Data were submitted to two-way ANOVA (α = 5 %) and Tukey test. Failure mode was analysed using SEM. Four 3D finite element (FE) models were constructed and static, linear and elastic analyses were performed. Maximum principal and von Mises stresses were evaluated. RESULTS: All specimens survived the mechanical fatigue simulation. No statistical difference in fracture resistance was recorded between FRC + CFC and CFC only, considering both loading angles (p = 0.115). However, the 0° loading showed a statistical significant higher strength than the 45° loading (p = 0.000). Failure mode analysis revealed more repairable fractures upon 0° loading, versus more root fractures (unrepairable) upon 45° loading. FE revealed a higher amount of stress upon 45° loading, with tensile stress being imposed to the lingual cervical area. CONCLUSION: The fracture strength was not increased using the FRC. Loading at a 45° decreased significantly the fracture resistance. CLINICAL RELEVANCE: The restoration of extensive cavities in posterior tooth is a challenge for the clinicians and the choice of the material that increases the fracture strength of tooth-restoration complex is required.

In situ assessment of effects of the bromide- and fluoride-incorporating adhesive systems on biofilm and secondary caries.

AIM: This in situ study assessed the effects of adhesive systems containing or not fluoride and/or the antibacterial monomer 12-methacryloyloxydodecylpyridinium bromide (MDPB) on the microbiological composition of dental biofilm and enamel demineralization. MATERIALS AND METHODS: During two phases of 14 days, ten volunteers wore intraoral palatal appliances containing two slabs of human enamel according to a double-blind, crossover design. The slabs were randomly restored using a composite resin and one of the following adhesive systems: All-Bond SE(TM) (self-etch, fluoride/MDPB free adhesive, AB) and Clearfl Protect Bond (self-etch containing fluoride and MDPB adhesive, CB). The biofilm formed on the slabs was analyzed with regard to total and mutans streptococci and lactobacilli counts. Demineralization represented by integrated area of hardness × lesion depth Delta S ( ΔS) was determined on enamel by analysis of cross-sectional microhardness, at 20 and 70 µm from the restoration margin. Data were analyzed by ANOVA. RESULTS: No statistically significant difference was found either in enamel demineralization or in the microbiological composition of dental biofilm. CONCLUSION: All adhesive systems containing or not fluoride and/or MDPB tested were unable to inhibit secondary caries in the in situ model used in the present research.

Impact of intracoronal dentin treatment prior to bleaching on bond strength of restorative materials.

Surface treatment of dentin before the bleaching procedure may affect its permeability and influence the bond strength of restorative materials. This study evaluated the influence of surface treatment before the bleaching on shear bond strength (SBT) of restorative materials to intracoronal dentin. Dentin slabs were subjected to surface treatment: no bleaching (control - CON), no surface treatment + bleaching (HP), 37% phosphoric acid + bleaching (PA) and Er:YAG laser + bleaching (L). After the bleaching procedure, specimens (n=10) were restored with: microhybrid composite resin (MH), flowable composite resin (F), and resin-modified glass-ionomer cement (RMGIC). The shear test was carried out. ANOVA and Tukey's test (α=0.05) showed significant difference for surface treatment and restorative materials (p<0.05). CON presented higher STB and was statistically different from HP (p<0.05). PA and L showed intermediate values and were statistically similar to CON and HP (p>0.05). STB for MH and F were higher than RMGIC (p<0.05), and did not differ from each other (p>0.05). The surface treatments with phosphoric acid and Er:YAG laser before the bleaching procedure provided shear bond strength at the same level of unbleached dentin and the composite resins presented superior bond strength to the intracoronal dentin.

Assessment of the quality of resin-dentin bonded interfaces: an AFM nano-indentation, µTBS and confocal ultramorphology study.

OBJECTIVE: The aim of this study was to assess by using confocal microscopy (CLSM), AFM nano-indentation and microtensile bond strength test (µTBS) the quality of the resin-dentin interfaces created with selected bonding parameters. METHODS: Dentin conditioned with H(3)PO(4) or EDTA was bonded in ethanol- or water-wet condition using a HEMA-free or HEMA-containing adhesive. The resin-bonded teeth were stored in distilled water (24h) and sectioned as match-sticks (0.9 mm(2)) for µTBS. Further resin-bonded teeth were sectioned and analyzed using CLSM, and AFM nano-indentation. The AFM imaging and nano-indentation processes were undertaken using a Berkovich diamond indenter. The modulus of elasticity (Ei) and hardness (Hi) across the interface were evaluated with the specimens in a fully hydrated status. The AFM imaging was performed both in dry and wet conditions for evaluating the shrinkage of the hybrid layer on dehydration. RESULTS: The HEMA-containing adhesive applied onto H(3)PO(4)-etched ethanol or water-wet dentin created hybrid layers with the lowest biomechanical nano-properties (p<0.05); no significant differences in µTBS were found between the two wet-bonding techniques (p>0.05). However, the ethanol-wet bonding reduced the dye penetration into the adhesive layer created with the HEMA-containing adhesive. Hybrid layers with high biomechanical properties, low micropermeability and no shrinkage were only possible when using HEMA-free adhesive applied in ethanol wet-dentin. In particular, a significant increase in Ei and Hi was achieved at the hybrid layer and underneath the resin-dentin interface of ethanol-wet EDTA-treated dentin. SIGNIFICANCE: The use of HEMA-free adhesives applied onto ethanol-wet dentin may be considered as an alternative and suitable bonding strategy to achieve high quality resin-dentin interfaces.

Assessment of bactericidal effects of quaternary ammonium-based antibacterial monomers in combination with colloidal platinum nanoparticles.

Pretreatment of dentin using colloidal platinum nanoparticles (CPtN) can enhance the bond strength of dentin adhesives. However, the combination of CPtN, which is negatively charged, with cationic monomer-containing adhesive may reduce the antibacterial activity of the original material. Thus, the purpose of this study was to assess the effect of CPtN on the bactericidal activity of two cationic antibacterial monomers, 12-methacryloyloxydodecylpyridinium bromide (MDPB) and methacryloxylethyl cetyl dimethyl ammonium chloride (DMAE-CB). The rapid killing effects of the two monomers against planktonic or attached Streptococcus mutans in the presence or absence of CPtN were examined by viable cell counts. The measurement of minimum inhibitory and bactericidal concentrations demonstrated that CPtN up to 2.5 mM has no antibacterial activity. In the absence of CPtN, rapid killing of both planktonic and attached Streptococcus mutans were achieved by the two cationic monomers. Combination with 0.1 mM CPtN did not reduce the bactericidal effects of the two monomers, indicating that CPtN may be used as a pretreatment with antibacterial adhesives.

Non-destructive assessment of cavity wall adaptation of class V composite restoration using swept-source optical coherence tomography.

The purpose of this study was to evaluate gap formations under class V restoration using swept-source optical coherence tomography (SS-OCT). Wedge-shaped cavities were prepared on the buccal surface of 40 extracted premolar teeth at 2 locations; 1) cemento-enamel junction (CEJ) with enamel and cementum margin and 2) root surfaces with cementum margin. The cavity was treated with Clearfil S(3) Bond, restored with Clearfil Majesty and polished with abrasive disks. The specimens were kept in water at 37°C for 24 hours and subjected to a thermocycling procedure. Gap formations at the tooth-restoration interface were measured with SS-OCT image and conventional dye leakage under a microscope. There was no effect of the locations of the cavity and the margins of the cavity on the gap formation. Therefore, a significant effect of the observational methods was observed. The gap formation was 0.89±0.48 mm with the SS-OCT, and the gap formation was 0.34±0.41 mm with the dye leakage. The observation with SS-OCT demonstrated a greater degree of gap formation than the observation with dye leakage.

Assessment of the nanostructure of acid-base resistant zone by the application of all-in-one adhesive systems: Super dentin formation.

An acid-base resistant zone (ABRZ) has been shown to be created under a hybrid layer in a self-etching adhesive system at the adhesive/dentin interface. The purpose of this study was to assess the nanostructure of the ABRZ by applying all-in-one adhesive systems. Human premolar dentin was treated with one of two all-in-one adhesive systems; Clearfil Tri-S Bond and G-Bond according to the manufacturers' instructions. After placement of a resin composite, the bonded interface was vertically sectioned and subjected to an acid-base challenge. Following this, the nanostructure of the ABRZ was examined by SEM and TEM. The SEM observations of the adhesive-dentin interface after the acid-base challenge indicated that a hybrid layer less than 1 mum thick was created, and a ABRZ was formed beneath the hybrid layer for each adhesive system. The TEM observations indicated that the ABRZ contained mineral components in both adhesive systems, however, the thickness of the ABRZ was material dependent. The application of the all-in-one adhesive systems created an ABRZ at the underlying dentin, which reinforced normal dentin against dental caries. Therefore, this zone was named 'Super Dentin'. Formation of 'Super Dentin' is a new approach in caries prevention.

In vitro assessment of solvent evaporation from commercial adhesive systems compared to experimental systems.

Solvents should be properly evaporated after application to dental substrates. The aim of this study was to assess the evaporation of commercial, experimental and neat solvents. The tested null hypotheses were that there are no differences in solvent evaporation regardless of its formulation and over time. Evaporation from commercial adhesive systems (Scotchbond Multipurpose Primer, Scotchbond Multipurpose Adhesive, Prime & Bond NT, Multi Bond, Excite, Single Bond 2, Adhese Primer, Adhese Bond, Xeno III A and Xeno III B) and experimental primers (35% HEMA plus 65% acetone or ethanol or water v/v) were compared to neat solvents (acetone, ethanol and water). Samples (10 microL) of these products were dripped into glass containers placed on a digital precision balance. Evaporation was assessed at 0, 5, 10, 15, 30, 60, 120, 300 and 600 s times to calculate mass loss. Data were analyzed statistically by ANOVA and Bonferroni's correction (a=0.05). Acetone-based products exhibited a remarkable capacity to evaporate spontaneously over time. Neat acetone evaporated significantly more than the HEMA-mixtures and the commercial formulations (p<0.05). The incorporation of monomers and other ingredients in the commercial formulations seem to reduce the evaporation capacity. Solvent evaporation was time and material-dependent.