High-Performance Bioinspired Microspheres for Boosting Dental Adhesion.

Dental adhesives are widely used in daily practice for minimally invasive restorative dentistry but suffer from bond degradation and biofilm attack. Bio-inspired by marine mussels having excellent surface-adhesion capability and high chemical affinity of polydopamine (PDA) to metal ions, herein, experimental zinc (Zn)-containing polydopamine-based adhesive formulation, further being referred to as "Zn-PDA@SiO2"-incorporated adhesive is proposed as a novel dental adhesive. Different Zn contents (5 and 10 mm) of Zn-PDA@SiO2 are prepared. Considering the synergistic effect of Zn and PDA, Zn-PDA@SiO2 not only presents excellent antibacterial potential and notably inhibits enzymatic activity (soluble and matrix-bound proteases), but also exhibits superior biocompatibility and biosafety in vitro/vivo. The long-term bond stability is substantially improved by adding 5 wt% 5 mm Zn-PDA@SiO2 to the primer. The aged bond strength of the experimentally formulated dental adhesives applied in self-etch (SE) bonding mode is 1.9 times higher than that of the SE gold-standard adhesive. Molecular dynamics calculations indicate the stable formation of covalent bonds, Zn-assisted coordinative bonds, and hydrogen bonds between PDA and collagen. Overall, this bioinspired dental adhesive provides an avenue technology for innovative biomedical applications and has already revealed promising perspectives for dental restorative dentistry.

Adhesive sonic agitation improves bonding durability to class-II cavity preparation.

The purpose of this study was to evaluate the effect of adhesive sonic agitation on resin-dentin micro-tensile bond strength (µTBS) and interfacial morphology at the gingival wall of class-II cavity preparation. Seventy-two molars with prepared class-II cavities were divided into six groups (n = 12) according to the bonding mode; etch-and-rinse (E&R) or self-etch (SE) and application protocol of the universal adhesive (UA) employed (Clearfil Universal Bond Quick, Kuraray Noritake); following the manufacturer instructions (MI), manual agitation for 20 s (20s), or sonic agitation for 20 s using a modified sonic micro-brush mounted on EndoActivator device, Dentsply Sirona, (sonic). Restored teeth were sectioned into resin-dentin beams and slaps and µTBS was evaluated at 1 week (1w) and after thermocycling (10k). µTBS data were analyzed using the linear mixed-effects modeling with specific contrast (p < 0.05). The resin-dentin interfacial morphology was evaluated using a scanning electron microscope. Adhesive sonic agitation resulted in significantly higher µTBS means in both E&R and SE modes, compared to MI group. The µTBS of MI group showed significant reduction upon aging when applied in SE mode. Sonic agitation was associated with enhanced adhesive infiltration into dentin specially in E&R mode. Sonic agitation of UA using modified sonic micro-brush attached to EndoActivator device significantly improved the resin-dentin µTBS and interfacial morphology at the gingival wall of class-II cavity preparation.

Quick bonding using a universal adhesive.

OBJECTIVES: This study aimed to measure the microtensile bond strength (µTBS) of a new universal adhesive (UA) bonded to dentin following a quick bonding mode. MATERIALS AND METHODS: The experimental UA 'SKB-100,' now commercialized as Clearfil Universal Bond Quick ('C-UBq'; Kuraray Noritake), was investigated, with Scotchbond Universal ('SBU'; 3M Oral Care) and the two-step self-etch (SE) adhesive Clearfil SE Bond 2 ('C-SE2'; Kuraray Noritake) serving as references. The adhesives were employed separately in etch&rinse (E&R) and SE modes on each tooth half following a split-tooth design and following their respective instructions for use, except for C-UBq that besides the manufacturer's instructed quick bonding mode was also applied and left untouched for 20 s prior to light curing ('C-UBq_20s') and for C-SE2 that was also applied in the E&R mode. µTBS of half of the specimens was measured upon 1 week (1w), with the other half tested after 6-month (6m) storage in distilled water at 37 °C. Data were statistically analyzed using linear mixed-effects modeling and three-way ANOVA (p < 0.05). The adhesive-dentin interfaces were ultrastructurally characterized by TEM. RESULTS: C-UBq revealed a significantly lower µTBS than C-SE2. The highest µTBS was recorded for C-UBq_20s_1w and C-SE2_1w, both when applied in E&R mode. However, µTBS of C-UBq_20s significantly decreased upon aging in both modes. C-SE2 presented the significantly highest 'aged' µTBS. CONCLUSION: C-UBq applied in the quick bonding mode did not underperform to the UAs applied for 20 s. Superior bonding effectiveness was achieved by C-SE2 in SE and E&R bonding modes. CLINICAL RELEVANCE: Extended application time of C-UBq improved solely its immediate but not aged bonding effectiveness.

Multi-Parameter Characterization of HEMA/BPA-free 1- and 2-step Universal Adhesives Bonded to Dentin.

PURPOSE: This study aimed to investigate the bonding effectiveness of two HEMA/BPA-free universal adhesives (UAs) to flat dentin, to characterize their adhesive-dentin interfacial ultrastructure, and to measure their water sorption (Wsp), water solubility (Wsl), and hydrophobicity. MATERIALS AND METHODS: The immediate and aged (50,000 thermocycles) microtensile bond strength (µTBS) to flat dentin of the HEMA/BPA-free UAs Healbond Max (HbMax; Elsodent) and Healbond MP (HbMP; Elsodent) as well as the reference adhesives OptiBond FL (Opti-FL; Kerr), Clearfil SE Bond 2 (C-SE2; Kuraray Noritake), and Scotchbond Universal (SBU; 3M Oral Care) was measured. The adhesive-dentin interfaces of HbMax and HbMP were characterized by TEM. Wsp and Wsl of all adhesive resins and of the primer/adhesive resin mixtures of HbMax, Opti-FL, and C-SE2 were measured. Hydrophobicity was determined by measuring the contact angle of water dropped on adhesive-treated dentin. RESULTS: In terms of µTBS, HbMax and HbMP performed statistically similarly to Opti-FL and C-SE2, but outperformed SBU. Aging only significantly reduced the µTBS of SBU when applied in E&R bonding mode. TEM revealed typical E&R and SE hybrid-layer ultrastructures at dentin, while electron-lucent globules of unknown origin, differing in size and shape, were observed within the adhesive resin of HbMP and even more frequently in that of HbMax. Higher Wsp was measured for the primer/adhesive resin mixtures than for the adhesive resins. Opti-FL was more hydrophobic than all other adhesives tested. CONCLUSION: The HEMA/BPA-free UAs bonded durably to flat dentin with bond strengths comparable to those of the gold-standard E&R/SE adhesives and superior to that of the HEMA/BPA-containing 1-step UA.

Bonding of Composite Cements Containing 10-MDP to Zirconia Ceramics Without Dedicated Ceramic Primer.

PURPOSE: To measure zirconia-to-zirconia microtensile bond strength (µTBS) using composite cements with and without primer. MATERIALS AND METHODS: Two Initial Zirconia UHT (GC) sticks (1.8x1.8x5.0 mm) were bonded using four cements with and without their respective manufacturer's primer/adhesive (G-CEM ONE [GOne] and G-Multi Primer, GC; Panavia V5 [Pv5]), and Panavia SA Cement Universal [PSAu], and Clearfil Ceramic Plus, Kuraray Noritake; RelyX Universal (RXu) and Scotchbond Universal Plus [SBUp], 3M Oral Care). Specimens were trimmed to an hour-glass shaped specimen whose isthmus is circular in cross-section. After 1-week water storage, the specimens were either tested immediately (1-week µTBS) or first subjected to 50,000 thermocycles (50kTC-aged µTBS). The fracture mode was categorized as either adhesive interfacial failure, cohesive failure in composite cement, or mixed failure, followed by SEM fracture analysis of selected specimens. Data were analyzed using linear mixed-effects statistics (α = 0.05; variables: composite cement, primer/adhesive application, aging). RESULTS: The statistical analysis revealed no significant differences with aging (p = 0.3662). No significant difference in µTBS with/without primer and aging was recorded for GOne and PSAu. A significantly higher µTBS was recorded for Pv5 and RXu when applied with their respective primer/adhesive. Comparing the four composite cements when they were applied in the manner that resulted in their best performance, a significant difference in 50kTC-aged µTBS was found for PSAu compared to Pv5 and RXu. A significant decrease in µTBS upon 50kTC aging was only recorded for RXu in combination with SBUp. CONCLUSION: Adequate bonding to zirconia requires the functional monomer 10-MDP either contained in the composite cement, in which case a separate 10-MDP primer is no longer needed, or in the separately applied primer/adhesive.

Antibacterial Dental Adhesive Containing Cetylpyridinium Chloride Montmorillonite.

Oral bacteria cause tooth caries and periodontal disease. Much research is being conducted to prevent both major oral diseases by rendering dental materials' antimicrobial potential. However, such antimicrobial materials are regarded as 'combination' products and face high hurdles for regulatory approval. We loaded inorganic montmorillonite with the antimicrobial agent cetylpyridinium chloride, referred to below as 'CPC-Mont'. CPC-Mont particles in a 1, 3 and 5 wt% concentration were added to the considered gold-standard self-etch adhesive Clearfil SE Bond 2 ('CSE2'; Kuraray Noritake) to render its antibacterial potential (CSE2 without CPC-Mont served as control). Besides measuring (immediate) bonding effectiveness and (aged) bond durability to dentin, the antibacterial activity against S. mutans and the polymerization-conversion rate was assessed. Immediate and aged bond strength was not affected by 1 and 3 wt% CPC-Mont addition, while 5 wt% CPC-Mont significantly lowered bond strength and bond durability. The higher the concentration of the antimicrobial material added, the stronger the antimicrobial activity. Polymerization conversion was not affected by the CPC-Mont addition in any of the three concentrations. Hence, adding 3 wt% CPC-Mont to the two-step self-etch adhesive rendered additional antimicrobial potential on top of its primary bonding function.

Experimental two-step universal adhesives bond durably in a challenging high C-factor cavity model.

OBJECTIVES: To determine the bonding effectiveness of experimental 2-step universal adhesives (UAs) to high C-factor class-I cavity-bottom dentin and to assess the potential bond-strength contribution of an additional flowable composite layer. METHODS: Three experimental 2-step UA formulations, involving the application of a 10-MDP-based primer followed by a hydrophobic adhesive resin with a 15-to-20-µm film thickness and differing only for filler, referred to as BZF-21 (silica and bioglass filler), BZF-29 (silica filler) and BZF-29_hv (higher silica-filler loading resulting in a higher viscosity), all prepared by GC, along with three representative commercial adhesives, Clearfil SE Bond 2 (C-SE2, Kuraray Noritake), G-Premio Bond (G-PrB, GC) and OptiBond FL (Opti-FL, Kerr), were comparatively investigated for their 'immediate' and 'aged' (50,000 thermocycles) micro-tensile bond strength (µTBS), when applied either in etch-and-rinse (E&R) or self-etch (SE) mode, to high C-factor class-I cavity-bottom dentin (n = 10; 10 experimental groups). Four additional experimental groups involved the extra application of the flowable composite G-ænial Universal Flo (GC), employed as an intermediate liner in combination with the adhesives BZF-29 and G-PrB and again applied both in E&R or SE mode. Statistical analysis was performed using linear mixed-effects (LME) modelling and linear regression analysis (p < 0.05). RESULTS: All 2-step UAs performed similarly when compared to the gold-standard E&R Opti-FL and SE C-SE2 adhesives, except for the aged µTBS of BZF-29_hv applied in E&R mode, and significantly outperformed the 1-step UA G-PrB. Significant reduction in µTBS upon aging was only recorded for 2-step UAs applied in E&R mode. The extra flowable composite layer significantly improved G-PrB's µTBS. SIGNIFICANCE: The experimental 2-step UAs revealed favorable bonding performance in the challenging high C-factor class-I cavity model, comparable to that of the multi-step gold-standard E&R and SE adhesives and superior to that of the 1-step UA investigated. An additionally applied flowable composite layer compensated for the lower bonding effectiveness of the 1-step UA in the high C-factor cavity model.

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.

Tissue-Mimetic Supramolecular Polymer Networks for Bioelectronics.

Addressing the mechanical mismatch between biological tissue and traditional electronic materials remains a major challenge in bioelectronics. While rigidity of such materials limits biocompatibility, supramolecular polymer networks can harmoniously interface with biological tissues as they are soft, wet, and stretchable. Here, an electrically conductive supramolecular polymer network that simultaneously exhibits both electronic and ionic conductivity while maintaining tissue-mimetic mechanical properties, providing an ideal electronic interface with the human body, is introduced. Rational design of an ultrahigh affinity host-guest ternary complex led to binding affinities (>1013  M-2 ) of over an order of magnitude greater than previous reports. Embedding these complexes as dynamic cross-links, coupled with in situ synthesis of a conducting polymer, resulted in electrically conductive supramolecular polymer networks with tissue-mimetic Young's moduli (<5 kPa), high stretchability (>500%), rapid self-recovery and high water content (>84%). Achieving such properties enabled fabrication of intrinsically-stretchable stand-alone bioelectrodes, capable of accurately monitoring electromyography signals, free from any rigid materials.

Optimizing glass-ceramic bonding incorporating new silane technology in an experimental universal adhesive formulation.

OBJECTIVE: Incorporating silane-coupling agent into universal adhesives (UAs) to simplify adhesive luting of glass-ceramic restorations appeared ineffective due to silane's instability in an acidic aqueous solution. This study aimed to evaluate new silane technology added to an experimental UA to be bonded to glass ceramics without separate prior silanization. METHODS: Combined silane technology, consisting of 3-(aminopropyl)triethoxysilane (APTES) and γ-methacryloxypropyltriethoxysilane (γMPTES), was incorporated into an experimental UA formulation, being referred to as ADH-XTE (3M Oral Care). Immediate and aged shear bond strength (SBS) of ADH-XTE onto as-milled ('AM'), tribochemical silica-coated ('TSC'), HF-etched ('HF'), and mirror-polished ('MP') glass-ceramic CAD/CAM blocks (IPS e.max CAD) with/without separate silanization was measured (n = 10/group). The control adhesives included Scotchbond Universal ('SBU') and Scotchbond 1 XT ('SB1-XT'). The glass-ceramic surface topography and the fractography of the SBS-debonded specimens were observed by SEM. RESULTS: Without separate prior silanization, the experimental UA ADH-XTE, containing combined APTES/γMPTES silane technology, significantly outperformed the glass-ceramic bonding efficiency of its silane-containing SBU precursor, while it performed equally effective as SBU applied with prior silanization. Upon aging, significant reduction in SBS was recorded when ADH-XTE was bonded to TSC glass-ceramic surfaces (p < 0.05), while not to HF ones. Notably, the lowest SBS was obtained when the UAs were bonded to AM and MP glass-ceramic surfaces, in particular when applied without separate prior silanization (p < 0.05). SIGNIFICANCE: The glass-ceramic bonding capacity of the new combined APTES/γMPTES silane-containing UA ADH-XTE surpassed that of its SBU precursor. HF etching remains needed to durably bond to glass-ceramics.

Extra Bonding Layer Compensates Universal Adhesive's Thin Film Thickness.

PURPOSE: Universal adhesives (UAs) are applied in 2-step etch-and-rinse (2-E&R) or 1-step self-etch (1-SE) mode. This study investigated whether three UAs could benefit from a highly filled extra bonding layer (EBL), turning them into 3-E&R and 2-SE UAs, respectively, thus also compensating for the commonly thin film thickness of UAs. MATERIALS AND METHODS: Microtensile bond strength (µTBS) to bur-cut dentin of Clearfil Universal Bond Quick (C-UBq, Kuraray Noritake), G-Premio Bond (G-PrB, GC) and Prime&Bond Active (P&Ba, Dentsply Sirona), applied in E&R and SE mode without/with the adhesive resin (EBL) of OptiBond FL (Opti-FL_ar, Kerr), was compared to that of the 3-E&Ra OptiBond FL (Opti-FL; Kerr), which was also employed in 2-SE mode. As a cross reference, the SE primer of Clearfil SE Bond 2 (Kuraray Noritake) was combined with Opti-FL_ar (C-SE2/Opti-FL) and again applied in 2-SE and 3-E&R mode. µTBS was measured after 1 month of water storage (37°C) and additional 25,000 and 50,000 thermocycles (TC). All µTBS were statistically analyzed using three different linear mixed-effects models with specific contrasts (p < 0.05). RESULTS: Overall, the four parameters (adhesive, bonding mode, aging, EBL) significantly influenced µTBS. G-PrB and P&Ba benefited from EBL when applied in both E&R and SE bonding modes. In E&R mode, P&Ba generally revealed the highest µTBS; C-UBq presented an intermediate and G-PrB the lowest µTBS. No significant differences were found between different bonding modes. C-SE2/Opti-FL outperformed Opti-FL in 3-E&R and 2-SE_1 month/25k. CONCLUSION: The overall benefit of EBL on the 1-month and TC-aged bonding efficacy differed for the different UAs tested.

Bonding Efficacy of a New Self-Adhesive Restorative onto Flat Dentin vs Class-I Cavity-bottom Dentin.

PURPOSE: This study investigated the bonding efficacy of a new so-called self-adhesive composite hybrid onto flat (FLAT) and high C-factor class-I cavity-bottom (CAVITY) dentin. MATERIALS AND METHODS: The immediate and aged (50,000 thermocycles) microtensile bond strength (µTBS) to FLAT and CAVITY dentin of the experimental self-adhesive bulk-fill restorative (K-0180 ASAR pilot [ASAR-pilot], Dentsply Sirona) was compared to that of two universal adhesives applied in self-etch mode and combined with a bulk-fill composite (Prime&Bond Elect/QuiXfil [P&Be/QuiXF], Prime&Bond Active/QuiXfil [P&Ba/QuiXF], both Dentsply Sirona), two pre-conditioned materials (Activa Bioactive-Restorative [Activa], Pulpdent; Fuji II LC Improved [Fuji2LC], GC); and one bulk-fill glass-hybrid restorative (Equia Forte Fil [EquiaF], GC). Statistically significant differences were recorded using Welch's ANOVA with Games-Howell contrast (p < 0.05). RESULTS: No significant difference in immediate µTBS was recorded when the restorative materials were applied onto FLAT dentin, except for Activa_FLAT and EquiaF_FLAT. When bonded to CAVITY dentin, the significantly highest µTBS was recorded for Fuji2LC_CAVITY (layer filled), and was not significantly different only from P&Ba/QuiXF_CAVITY. Upon aging, the highest µTBS to flat dentin was achieved by ASAR-pilot_FLAT, which was not significantly different from P&Be/QuiXF_FLAT and Fuji2LC_FLAT. No significant difference between immediate and aged µTBS was recorded for ASAR-pilot when bonded onto FLAT or CAVITY dentin; the latter, however, was associated with low bond strength. CONCLUSION: Favorable bonding performance was found for the new self-adhesive bulk-fill composite hybrid ASAR-pilot when bonded to flat dentin. However, much lower bond strength was recorded when ASAR-pilot was bonded to high C-factor cavity-bottom dentin.

Structural/Chemical Characterization and Bond Strength of a New Self-Adhesive Bulk-fill Restorative.

PURPOSE: The material structure and chemical elemental composition of a new self-adhesive composite hybrid were investigated. The bonding performance when applied on flat (FLAT) vs high C-factor class-I cavity-bottom (CAVITY) dentin and in light-cure (LC) vs self-cure (SC) mode was determined. MATERIALS AND METHODS: The self-adhesive bulk-fill composite Surefil One (Su-O; Dentsply Sirona) was compared with the resin-modified glass-ionomer Fuji II LC Improved (Fuji2LC; GC) and the ion-releasing alkasite material Cention N (CentionN; Ivoclar Vivadent). The material structure was examined with SEM and TEM, while the chemical elemental composition was analyzed using EDS. The immediate and aged microtensile bond strength (µTBS) of Su-O_LC/SC was compared to that of Fuji2LC applied without any pre-treatment, and to that of CentionN applied following bonding with Adhese Universal (AU) (Ivoclar Vivadent) in self-etch mode (AU/CentionN). All restorative materials were bonded onto FLAT and CAVITY dentin. Statistical analysis was performed with the Kruskal-Wallis nonparametric test. RESULTS: EDS analysis revealed that Su-O was richer in C and P than the reference restorative materials. Applied to FLAT dentin, the significantly highest immediate and aged µTBS were recorded for AU/CentionN, which were not significantly different only from Su-O_LC. Applied to CAVITY dentin, the significantly highest immediate µTBS was recorded for AU/CentionN, which did not differ significantly only from Su-O_SC. Su-O_LC bonded to CAVITY dentin suffered from a high incidence of pre-test failures. CONCLUSION: While Su-O_LC bonded effectively and durably to FLAT dentin, Su-O_SC bonded more favorably than Su-O_LC in class-I cavities, which was probably related to shrinkage stress variously challenging the respective bond.

Zinc-Calcium-Fluoride Bioglass-Based Innovative Multifunctional Dental Adhesive with Thick Adhesive Resin Film Thickness.

Apart from producing high bond strength to tooth enamel and dentin, a dental adhesive with biotherapeutic potential is clinically desirable, aiming to further improve tooth restoration longevity. In this laboratory study, an experimental two-step universal adhesive, referred to as Exp_2UA, applicable in both the etch-and-rinse (E&R) and self-etch (SE) modes and combining a primer, containing 10-methacryloyloxydecyldihydrogen phosphate as a functional monomer with chemical binding potential to hydroxyapatite, with a bioglass-containing hydrophobic adhesive resin, was multifactorially investigated. In addition to primary property assessment, including measurement of bond strength, water sorption, solubility, and polymerization efficiency, the resultant adhesive-dentin interface was characterized by transmission electron microscopy (TEM), the filler composition was analyzed by energy-dispersive X-ray spectroscopy, and the bioactive potential of the adhesive was estimated by measuring the long-term ion release and assessing its antienzymatic and antibacterial potential. Four representative commercial adhesives were used as reference/controls. Application in both the E&R and SE modes resulted in a durable bonding performance to dentin, as evidenced by favorable 1 year aged bond strength data and a tight interfacial ultrastructure that, as examined by TEM, remained ultramorphologically unaltered upon 1 year of water storage aging. TEM revealed a 20 µm thick hydrophobic adhesive layer with a homogeneous bioglass filler distribution. Adequate polymerization conversion resulted in extremely low water sorption and solubility. In situ zymography revealed reduced endogenous proteolytic activity, while Streptococcus mutans biofilm formation was inhibited. In conclusion, the three-/two-step E&R/SE Exp_2UA combines the high bonding potential and bond degradation resistance with long-term ion release, rendering the adhesive antienzymatic and antibacterial potential.

Universal Adhesives Benefit from an Extra Hydrophobic Adhesive Layer When Light Cured Beforehand.

PURPOSE: To measure microtensile bond strength (µTBS) of universal adhesives immediately and after 6-month aging, with or without an additional adhesive layer applied on a separately light-cured or non-light-cured universal adhesive. MATERIALS AND METHODS: Eighty human third molars were randomly assigned to 8 experimental groups. The universal adhesives Clearfil Universal Bond (Kuraray Noritake) and Single Bond Universal (3M Oral Care) were used in self-etch mode (following the manufacturer's directions), and either light cured or not before application of an extra hydrophobic adhesive layer (Clearfil SE Bond bond, Kuraray Noritake). The two-step self-etch adhesives Clearfil SE Bond (Kuraray Noritake) and OptiBond XTR (Kerr) were used as references. After composite buildups were bonded to mid-coronal occlusal dentin surfaces, the specimens were stored in water (37°C/24 h) and sectioned into microspecimens (0.96 ± 0.04 mm2). Half of the specimens were immediately subjected to µTBS testing (1.0 mm/min), while the other half was stored in water (37°C) for 6 months prior to testing. Failure analysis was performed using stereomicroscopy and SEM. Data were analyzed with two-way repeated measures ANOVA, Tukey's and paired t-tests (p = 0.05). RESULTS: The immediate µTBS was similar for the universal adhesives when applied following the different application strategies (p > 0.05). Application of an extra layer of hydrophobic adhesive improved the aged µTBS of the universal adhesives, which was statistically significant when the universal adhesives were first light cured (p < 0.05). The reference adhesives Clearfil SE Bond and OptiBond XTR exhibited a significantly higher immediate and aged µTBS to dentin than did the universal adhesives (p < 0.05). CONCLUSION: The bond durability of universal adhesives, applied in self-etch mode, was found to benefit from the application of an extra hydrophobic adhesive layer when the universal adhesives were first light cured.

Do Universal Adhesives Benefit from an Extra Bonding Layer?

PURPOSE: Universal adhesives use a combined primer/bonding resin applied either in 2-step etch-and-rinse (2-E&R) or 1-step self-etch (1-SE) mode. This study investigated whether three universal adhesives would benefit from an extra bonding layer (EBL), essentially making them 3-step E&R (3-E&R) and 2-SE adhesives, respectively. MATERIALS AND METHODS: Microtensile bond strengths (µTBSs) to bur-cut dentin of Clearfil Universal Bond Quick (C-UBq, Kuraray Noritake), G-Premio Bond (G-PrB, GC) and Prime&Bond Active (P&Ba, Dentsply Sirona) were compared to those of the 2-SEa Clearfil SE Bond 2 (C-SE2, Kuraray Noritake) which was also employed in 3-E&R mode. A split-tooth design was applied with each adhesive used in E&R and SE mode on each tooth, half without/with EBL (C-SE2 Bond). All adhesives were light cured after application of the final layer. The µTBS of one-third of the specimens was measured after 1-month water storage without thermocycling (TC), with the remaining two-thirds aged with 25,000 and 50,000 TCs. All µTBSs were statistically analyzed using a linear mixed-effects model with specific contrasts (p < 0.05). RESULTS: Overall, the four variables (adhesive, bonding mode, EBL, aging) significantly influenced µTBS. Solely G-PrB benefited from EBL when applied in SE mode. In E&R mode, P&Ba generally resulted in the highest µTBSs, C-UBq presented with intermediate and G-PrB with the lowest µTBSs, where the latter was significantly lower than the µTBSs recorded for C-SE2. In SE mode, P&Ba generally resulted in the highest µTBSs in 1- and 2-SE mode. Equally high µTBSs were recorded for G-PrB in 2-SE mode with EBL. Lower µTBSs were recorded for G-PrB in 1-SE mode and for C-UBq in 1- and 2-SE mode. CONCLUSION: The overall effect of EBL on immediate and aged bonding efficacy depended on the specific universal adhesive and its bonding mode.

Bonding to enamel using alternative Enamel Conditioner/etchants.

OBJECTIVE: Enamel bond durability of three new alternative etchants combined with three representative adhesives was determined. METHODS: The 'immediate' and 'aged' micro-tensile bond strength (µTBS) of the 3-step etch&rinse adhesive OptiBond FL ('O-FL', Kerr), 2-step self-etch (SE) adhesive Clearfil SE Bond 2 ('C-SE2', Kuraray Noritake) and universal adhesive Adhese Universal ('ADU', Ivoclar Vivadent) were measured when bonded to enamel following either a proprietary organic acid-containing Enamel Conditioner ('EC', Shofu), a phosphoric-acid monomer-containing Multi Etchant ('ME', Yamakin: 10-methacryloyloxy tetraethylene glycol dihydrogenphosphate or MTEGP), or a metal salt-based ZON etchant ('ZON', Ivoclar Vivadent: ZrO(NO3)2). All alternative etchants were used in replacement of phosphoric acid, the latter (K-Etchant, Kuraray Noritake) also used with O-FL and ADU, in addition to C-SE2 that was solely used in SE mode (controls). The enamel-etching patterns and de-bonded fracture surfaces were examined by SEM, while the interfaces with enamel were ultra-morphologically characterized by TEM. RESULTS: No statistically significant difference in immediate and aged µTBS, obtained by combining the three alternative etchants with the three adhesives, was recorded as compared with the respective controls, except for ME combined with O-FL. Upon aging, significant reduction in µTBS was recorded for the ME/C-SE2 and ME/ADU combinations. The percentage of adhesive failures increased with aging. SEM revealed similar etching patterns produced by EC and ZON as by classic phosphoric-acid etching, for which also numerous micro-resin tags at the adhesive-enamel interface were disclosed. SIGNIFICANCE: Durable bonding to enamel was generally obtained for all etchant/adhesive combinations with the exception of the ME/O-FL combination.

Impact of different malocclusion types on the vertical mandibular asymmetry in young adult sample.

OBJECTIVE: The aim of this study was to investigate the vertical mandibular asymmetry in a group of adult patients with different types of malocclusions, based on Angle's dental classification. MATERIALS AND METHODS: A sample of 102 patients (age range 19-28) who went for routine orthodontic treatment in the institution were divided into four groups: Class I, 26 patients; Class II/1, 30 patients; Class III, 23 patients; and control group (CG) with normal occlusion, 23 patients. Condylar asymmetry index (CAI), ramal asymmetry index (RAI), condylar-plus-ramal asymmetry index values were measured for all patients on panoramic radiographs. Data were analyzed using Kruskal-Wallis and Mann-Whitney U-test at the 95% confidence level (P < 0.05). RESULTS: The results of the analysis showed that different occlusal types significantly affected the vertical symmetry of the mandible at the condylar level. Class I and Class II/1 malocclusion groups showed a significant difference in CAI values relative to the CG (P < 0.05, P < 0.001). No statistically significant difference was found between the CG and Class III malocclusion group (P > 0.05). Comparisons between Class II/1 and Class I malocclusions revealed a significant difference in CAI values (P < 0.01). CONCLUSIONS: Both Class II/1 and Class I malocclusions patients had significantly higher CAI values compared to CG and Class III group. CAI value was significantly higher in Class II/1 malocclusion compared to Class I malocclusion. Both these malocclusions could act as a predisposing factor for having asymmetric condyles if left untreated.