Melatonin-doped polymeric nanoparticles induce high crystalline apatite formation in root dentin

ObjectiveTo investigate the effect of novel polymeric nanoparticles (NPs) doped with melatonin (ML) on nano-hardness, crystallinity and ultrastructure of the formed hydroxyapatite after endodontic treatment.MethodsUndoped-NPs and ML-doped NPs (ML-NPs) were tested at radicular dentin, after 24 h and 6 m. A control group without NPs was included. Radicular cervical and apical dentin surfaces were studied by nano-hardness measurements, X-ray diffraction and transmission electron microscopy. Mean and standard deviation were analyzed by ANOVA and Student-Newman-Keuls multiple comparisons (p < 0.05).ResultsCervical dentin treated with undoped NPs maintained its nano-hardness values after 6 m of storage being [24 h: 0.29 (0.01); 6 m: 0.30 (0.02) GPa], but it decreased at apical dentin [24 h: 0.36 (0.01); 6 m: 0.28 (0.02) GPa]. When ML-NPs were used, nano-hardness was similar over time [24h: 0.31 (0.02); 6 m: 0.28 (0.03) GPa], at apical dentin. Root dentin treated with ML-NPs produced, in general, high crystallinity of new minerals and thicker crystals than those produced in the rest of the groups. After 6 m, crystals became organized in randomly oriented polyhedral, square polygonal block-like apatite or drop-like apatite polycrystalline lattices when ML-NPs were used. Undoped NPs generated poor crystallinity, with preferred orientation of small crystallite and increased microstrain.SignificanceNew polycrystalline formations encountered in dentin treated with ML-NPs may produce structural dentin stability and high mechanical performance at the root. The decrease of mechanical properties over time in dentin treated without NPs indicates scarce remineralization potential, dentin demineralization and further potential degradation. The amorphous stage may provide high hydroxyapatite solubility and remineralizing activity.     

Melatonin-doped polymeric nanoparticles reinforce and remineralize radicular dentin: Morpho-histological,chemical and biomechanical studies

ObjectivesTo investigate the effectiveness of novel polymeric nanoparticles (NPs) doped with melatonin (ML) in reducing dentin permeability and facilitating dentin remineralization after endodontic treatment.MethodsThe effect of undoped NPs and ML-doped NPs (ML-NPs) was tested in radicular dentin, at 24 h and 6 m. A control group without NPs was included. ML liberation was measured. Radicular dentin was assessed for fluid filtration. Dentin remineralization was analyzed by scanning electron microscopy, AFM, Young’s modulus (Ei), Nano DMA-tan delta, and Raman analysis.ResultsML release ranged from 1.85 mg/mL at 24 h to 0.033 mg/mL at 28 d. Both undoped NPs and ML-NPs treated dentin exhibited the lowest microleakage, but samples treated with ML-NPs exhibited hermetically sealed dentinal tubules and extended mineral deposits onto dentin. ML-NPs promoted higher and durable Ei, and functional remineralization at root dentin, generating differences between the values of tan delta among groups and creating zones of stress concentration. Undoped-NPs produced closure of some tubules and porosities at the expense of a relative mineral amorphization. Chemical remineralization based on mineral and organic assessments was higher in samples treated with ML-NPs. When using undoped NPs, precipitation of minerals occurred; however, radicular dentin was not mechanically reinforced but weakened over time.SignificanceApplication of ML-NPs in endodontically treated teeth, previous to the canal filling step, is encouraged due to occlusion of dentinal tubules and the reinforcement of the radicular dentin structure.     

Raman spectroscopy for early detection and monitoring of dentin demineralization

Early detection of dental caries and variations in composition/structure of both enamel and dentin represents an important issue in modern dentistry. Demineralization has been associated to teeth discoloration, development of caries, and formation of cavities.ObjectiveIn this study, we systematically monitored the processes of demineralization/remineralization in dentin samples by means of three different spectroscopic techniques, namely, Raman spectroscopy, X-Ray Photo-electron spectroscopy (XPS), and X-Ray Diffractometry (XRD).MethodsBovine dentin samples were first exposed to acidic solutions and their structure systematically monitored as a function of time and pH. Then, the samples were rinsed in artificial saliva to simulate remineralization.ResultsThe above three spectroscopic techniques provided quantitative structural information spanning from the nanometer to the millimeter scale of sample penetration depth. An irreversible level of demineralization was reached when dentin was exposed to pH 2 beyond a time threshold of 6 h, successive treatments with artificial saliva being unable to restore the mineral fraction. On the other hand, short-term treatments at pH 5 and long-term treatments at pH 6 could partially or completely recover the dentin structure within one week of remineralization treatment.SignificanceTwo specific Raman parameters, namely, the bandwidth of the symmetric phosphate-stretching signal and the mineral-to-matrix intensity ratio, showed strong correlations with XPS and XRD data, and matched laser microscopy observations. Such correlations open the path to apply Raman spectroscopy in monitoring dentin demineralization in vivo and provide quantitative working algorithms for the prevention of oral caries.     

Impact of silanization of different bioactive glasses in simplified adhesives on degree of conversion,dentin bonding and collagen remineralization

ObjectiveTo analyze simplified adhesive containing pure or silanized bioglass 45S5 (with calcium) or Sr-45S5 (strontium-substituted) fillers applied on dentin and to evaluate the microtensile bond strength (µTBS), interface nanoleakage, degree of conversion of adhesive, collagen degradation and remineralization.MethodsAmbar Universal adhesive (FGM) was doped with 10 wt% bioactive glasses to form following groups: Control (no bioglass), 45S5 (conventional bioglass 45S5), Sr-45S5 (Sr-substituted bioglass 45S5), Sil-45S5 (silanized bioglass 45S5) and Sil-Sr-45S5 (silanized bioglass Sr-45S5). Adhesives were applied after dentin acid-etching using phosphoric acid at extracted human molars. Resin-dentin sticks were obtained and tested for µTBS, nanoleakage at 24 h or 6 months. Degree of conversion was measured using micro-Raman spectroscopy. Dentin remineralization was assessed by FTIR after 6-month storage in PBS. Hydroxyproline (HYP) release was surveyed by UV-Vis spectroscopy. Statistical analysis was performed using ANOVA and Tukey’s test (p < 0.05).ResultsRegarding µTBS, Sr-45S5 and 45S5 presented higher and stable results (p > 0.05). Control (p = 0.018) and Sil-Sr-45S5 (p < 0.001) showed µTBS reduction after 6-month aging. Sil-Sr-45S5 showed higher HYP release than that obtained in the 45S5 group. Sil-45S5 showed mineral deposition and increase in µTBS (p = 0.028) after 6-months. All experimental adhesives exhibited higher degree of conversion compared to Control group, except for 45S5. All adhesives created gap-free interfaces, with very low silver impregnation, except for Sil-Sr-45S5.SignificanceThe incorporation of silanized 45S5 bioglass into the universal adhesive was advantageous in terms of dentin remineralization, bonding performance and adhesive polymerization. Conversely, Sil-Sr-45S5 compromised the µTBS, interface nanoleakage and had a negative impact on HYP outcomes.     

Chemical interaction of glycero-phosphate dimethacrylate (GPDM) with hydroxyapatite and dentin

Objectives

Although the functional monomer glycero-phosphate dimethacrylate (GPDM) has since long been used in several dental adhesives and more recently in self-adhesive composite cements and restoratives, its mechanism of chemical adhesion to hydroxyapatite (HAp) is still unknown. We therefore investigated the chemical interaction of GPDM with HAp using diverse chemical analyzers and ultra-structurally characterized the interface of a GPDM-based primer formulation with dentin.

不同粘接材料与牙本质粘接界面的元素分布分析

目的 通过能谱仪分析粘接材料与牙本质层界面间的元素分布,比较不同粘接材料与牙本质层的结合方式.方法 选用8颗离体下颌第一磨牙进行常规牙体预备,预备后基牙外形保持相对一致的高度.常规制作镍铬合金金属全冠.使用不同类型(玻璃离子、聚羧酸锌、树脂类)的8种粘接材料,按照厂家的要求进行粘接,试样保存于(23±1)℃,100％相对湿度的环境中,30d后用慢速锯将试样纵向切开,运用能谱分析仪观察粘接界面的形貌和元素分布,对粘接材料与牙本质的粘接界面进行线扫描和元素定量分析,观测元素质量分数的变化.结果 玻璃离子类粘接材料的元素分布在牙本质和粘接材料之间表现出明显的相互扩散现象,其中GC Fuji I最显著.树脂粘接材料具有树脂突混合层,微观界面结合表现较为致密.结论 不同类型的粘接材料,粘接界面的致密性和连续性存在差异.其中,复合树脂粘接材料与牙体粘接界面最致密,玻璃离子粘接材料与牙体粘接界面的元素扩散最为活跃.     

Nano-calcium phosphate and dimethylaminohexadecyl methacrylate adhesive for dentin remineralization in a biofilm-challenged environment

ObjectiveDentin remineralization at the bonded interface would protect it from external risk factors, therefore, would enhance the longevity of restoration and combat secondary caries. Dental biofilm, as one of the critical biological factors in caries formation, should not be neglected in the assessment of caries preventive agents. In this work, the remineralization effectiveness of demineralized human dentin in a multi-species dental biofilm environment via an adhesive containing nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM) was investigated.MethodsDentin demineralization was promoted by subjecting samples to a three-species acidic biofilm containing Streptococcus mutans, Streptococcus sanguinis, Streptococcus gordonii for 24 h. Samples were divided into a control group, a DMAHDM adhesive group, an NACP group, and an NACP + DMAHDM adhesive group. A bonded model containing a control-bonded group, a DMAHDM-bonded group, an NACP-bonded group, and an NACP + DMAHDM-bonded group was also included in this study. All samples were subjected to a remineralization protocol consisting of 4-h exposure per 24-h period in brain heart infusion broth plus 1% sucrose (BHIS) followed by immersion in artificial saliva for the remaining period. The pH of BHIS after 4-h immersion was measured every other day. After 14 days, the biofilm was assessed for colony-forming unit (CFU) count, lactic acid production, live/dead staining, and calcium and phosphate content. The mineral changes in the demineralized dentin samples were analyzed by transverse microradiography.ResultsThe in vitro experiment results showed that the NACP + DMAHDM adhesive effectively achieved acid neutralization, decreased biofilm colony-forming unit (CFU) count, decreased biofilm lactic acid production, and increased biofilm calcium and phosphate content. The NACP + DMAHDM adhesive group had higher remineralization value than the NACP or DMAHDM alone adhesive group.SignificanceThe NACP + DMAHDM adhesive was effective in remineralizing dentin lesion in a biofilm model. It is promising to use NACP + DMAHDM adhesive to protect bonded interface, inhibit secondary caries, and prolong the longevity of restoration.     

Enhanced effect of nano-monetite hydrosol on dentin remineralization and tubule occlusion

ObjectivesWe aim to investigate the dentin tubule occlusion and remineralization potential of a novel nano-monetite hydrosol (nMH).MethodsFirst, nano-monetite hydrosol (nMH) was fabricated by homogeneous precipitation method. Then, the effectiveness of toothpaste with nMH on improving remineralization was evaluated by the measurement of tubule occluding ratio and acid-resistant stability compared with dentifrices comprising nano-hydroxyapatite hydrosol (nHH) and bioactive glass (BG). To explain this result, we studied the ions releasing and remineralization based on gelatin scaffold among nMH, nHH and BG. Finally, the cytotoxicity of these three minerals on Human dental pulp stem cells (HDPSCs) was evaluated.ResultsProcessing for more than 7 days, the toothpaste containing nMH exhibited the significant remineralization potential and acid-resistant compared with two commercial de-sensitive dentifrices comprising nHH and BG. In addition, cytotoxicity test resulted that nMH has good cell compatibility to HDPSCs below extracts concentration of 3.12 mg/mL.SignificanceSmall size, the release of Ca²⁺ and PO₄³⁻ with high concentration, strongly binding on dental surface, and fast transformation to HAp, were all needed in the preparation of effective dentin tubule occluding biomaterials.     

六种粘接剂的牙本质粘接界面纳米渗漏比较

目的检测6种粘接剂粘接处理后牙本质粘接界面的纳米渗漏情况。方法选取12颗无龋人磨牙,用600目碳化硅砂纸在流水冲洗下预备出统一的牙本质粘接面玷污层。分别用6种粘接剂按使用说明进行粘接处理,切割成0.9mm厚试件,避光贮存于氨化硝酸银溶液中24h。透射电子显微镜下观察牙本质粘接界面的纳米渗漏情况,单因素方差分析比较各组银染颗粒分布面积比的均值。结果6种粘接剂的牙本质粘接界面在电子显微镜下均观察到明显的纳米渗漏,其中材料A[邦多,(16.09±2.08)%]、材料B[Single Bond,(13.39±1.81)%]和材料C[Prime&Bond NT,(11.27±1.94)%]之间的差异均有统计学意义(P<0.05);材料D[B1自酸蚀底涂剂,(12.13±2.11)%]与材料E[ClearfilTMSE Bond,(12.35±2.60)%]的差异无统计学意义,但两者的纳米渗漏均小于材料F[AdperTMPromptTM,(14.93±2.67)%],差异有统计学意义(P<0.05)。结论6种牙科粘接剂的牙本质粘接界面均存在不同程度的纳米渗漏。     

Stability and remineralization of proteoglycan-infused dentin substrate

ObjectiveThis study tested the effects of small leucine-rich proteoglycan (SLRP) proteins on phosphoric acid (PA)-treated dentin bonding overtime and the role of such SLRPs in the remineralization potential of demineralized dentin collagen.MethodsCoronal dentin sections of human molars were used. SLRPs were either decorin (DCN) or biglycan (BGN) in core or proteoglycan form (with glycosaminoglycans, GAGs). Groups were: No treatment (control), DCN core, DCN + GAGs, BGN core, BGN + GAGs. Samples were etched with PA for 15 s and prior to application of Adper Single Bond Plus and composite buildup an aliquot of the specific SLRPs was applied over dentin. Twenty-four hours or 6 months after the bonding procedure, samples were tested for microtensile bond strength (MTBS). Debonded beams were analyzed by scanning electron microscopy (SEM). For remineralization studies, dentin blocks were fully demineralized, infused with the SLRPs, placed in artificial saliva for 2 weeks, and evaluated by transmission electron microscopy (TEM).ResultsMTBS test presented a mean of 51.4 ± 9.1 MPa in control with no statistically significant difference to DCN core (47.6 ± 8.3) and BGN core (48.3 ± 6.5). The full proteoglycan groups DCN + GAGs (27.4 ± 4.5) and BGN + GAGs (36.4 ± 13.6) showed decreased MTBS compared to control (p < 0.001). At 6 months, control or core-treated samples did not have a statistically significant difference in MTBS. However, SLRPs with GAGs showed statistically significant improvement of bonding (62.5 ± 6.0 for DCN and 52.8 ± 8.1 for BGN, p < 0.001) compared to their baseline values. SEM showed that GAGs seem to favor water retention but overtime help remineralization. TEM of demineralized dentin indicated a larger collagen fibril diameter pattern of samples treated with core proteins compared to control and a smaller diameter with DCN + GAGs in water with evidence of mineralization with DCN + GAGS, BGN core and BGN + GAGs.Significance: In conclusion, core proteins seem not to affect dentin adhesion significantly but the presence of GAGs can be detrimental to immediate bonding. However, after ageing of samples, full proteoglycans, particularly DCN, can significantly improve bonding overtime while promoting remineralization which can prove to be clinically beneficial.     

Proanthocyanidin-functionalized hydroxyapatite nanoparticles as dentin biomodifier

ObjectiveThis study evaluated the potential combined effects of nanohydroxyapatite and proanthocyanidin on the remineralization and collagen stabilization of demineralized dentin.MethodsSeventy-five coronal dentin beams (6 × 1 × 1 mm³) were randomly allocated into five experimental groups (n = 15): Sound (no treatment), Control (pH-cycling), nHAp (nanohydroxyapatite), nHAp_PA (Proanthocyanidin-functionalized nanohydroxyapatite), and PA (proanthocyanidin) treatments. The sound group (negative control) were immersed in distilled water over the experimental period. The remaining groups were submitted to a pH-cycling process for 14 days. Following the de-re mineralization process, specimens corresponding to the control group (positive control) were immersed in distilled water whereas the test groups were immersed in 1 mL of respective solution treatment (nHAp, nHAp_PA, or PA) for 1 min. The dentin samples were analyzed to determine their chemical composition (ATR-FTIR and Thermogravimetric) and mineralogical (XRD) characteristics as well as their mechanical response, obtained by three-point bending test.ResultsHigher phosphate content (v₄ PO₄: ATR-FTIR) and amount of mineral (XRD) was observed in the nHAp_PA group. Furthermore, a larger induction of collagen cross-links (ATR-FTIR) and %Organic Matter (TGA) would indicate the PA incorporation and the achievement of dentin matrix stability. These effects on dentin properties were related to increasing flexural strength (MPa), demonstrating that 15% w/v nHAp_PA treatment improved the mechanical properties of the samples.SignificancenHAp_PA shows significant potential for promoting remineralization while improving collagen stability into demineralized dentin in a clinically feasible period of 1 min.     

葡萄籽提取物促进早期牙本质龋损再矿化作用的体外研究

目的评价葡萄籽提取物（GSE）对人工牙本质龋的再矿化作用和显微结构的影响。方法制备60个人牙本质标本,采用化学法形成人工牙本质龋损,将样本随机分为4组,分别用10%GSE溶液、1 mg/L NaF溶液、10%GSE+ 1 mg/L NaF溶液和去离子水（DDW）处理,进行体外pH循环。采用显微硬度计测定处理前、后各样本的显微硬度值,扫描电镜观察pH循环后各组牙本质显微结构的变化,并用X线能谱仪分析牙本质元素百分含量。采用SPSS17.0软件包对数据进行统计学分析。结果显微硬度结果显示,GSE组牙本质的显微硬度获得百分比（SMHR）为40.87±9.92,NaF组为44.60±12.48,GSE+NaF组为48.54±9.27,去离子水组为15.98±8.33。与去离子水组相比,3个实验组的SMHR值均显著提高（P<0.05）,但相互之间无显著差异。扫描电镜显示,GSE组、NaF组和GSE+NaF组牙本质小管大部分呈封闭状态,而去离子水组牙本质小管呈开放状态。元素分析结果显示,3个实验组的Ca、P百分含量均显著高于去离子水组（P<0.05）。结论GSE能显著促进人工牙本质龋的再矿化作用,抑制牙本质龋的进展。     

Effect of tetracalcium phosphate/monetite toothpaste on dentin remineralization and tubule occlusion in vitro

Objectives

To investigate the tubule occlusion and remineralization potential of a novel toothpaste with active tetracalcium phosphate/monetite mixtures under de/remineralization cycling.

Effect of dentin depth on hybridization quality using different bonding tactics in vivo

OBJECTIVES: Incomplete resin infiltration and polymerization of adhesive contributed to nanoleakage formation. This study tested the null hypothesis that adoption of different bonding tactics and dentine depth will not affect hybridization quality in vivo. METHODS: Class V cavities were prepared on the labial/buccal surface of monkey teeth. They were bonded by Single Bond (a two-step total-etch adhesive), Clearfil SE Bond (a two-step self-etch adhesive), or Clearfil S(3) Bond (an all-in-one self-etch adhesive). Combined nanoleakage analysis and quantitative immunolabeling evaluation were carried out in the hybrid layer formed in both cervical superficial and deep dentine. RESULTS: Single Bond showed reticular and spotted nanoleakage while Clearfil SE Bond and Clearfil S(3) Bond presented only a spotted one. While Single Bond showed increased concentration of labeling of type I collagen within the deep part of the hybrid layer, two self-etch adhesives-Clearfil SE Bond and Clearfil S(3) Bond revealed a homogeneous labeling pattern, even if the latter presented a significantly increased labeling index in deep dentine. CONCLUSIONS: Different bonding tactics showed different nanoleakage patterns and immunolabeling index, and was influenced by dentine depth at different levels in vivo.     

Phosphoric acid esters cannot replace polyvinylphosphonic acid as phosphoprotein analogs in biomimetic remineralization of resin-bonded dentin

Polyvinylphosphonic acid (PVPA), a biomimetic analog of phosphoproteins, is crucial for recruiting polyacrylic acid (PAA)-stabilized amorphous calcium phosphate nanoprecursors during biomimetic remineralization of dentin collagen matrices. This study tested the null hypothesis that phosphoric acid esters of methacrylates in dentin adhesives cannot replace PVPA during bimimetic remineralization of resin–dentin interfaces. Human dentin specimens were bonded with: (I) XP Bond, an etch-and-rinse adhesive using moist bonding; (II) XP Bond using dry bonding; (III) Adper Prompt L-Pop, a self-etching adhesive. The control medium contained only set Portland cement and a simulated body fluid (SBF) without any biomimetic analog. Two experimental Portland cement/SBF remineralization media were evaluated: the first contained PAA as the sole biomimetic analog, the second contained PAA and PVPA as dual biomimetic analogs. No remineralization of the resin–dentin interfaces could be identified from specimens immersed in the control medium. After 2–4 months in the first experimental medium, specimens exhibited either no remineralization or large crystal formation within hybrid layers. Only specimens immersed in the second remineralization medium produced nanocrystals that accounted for intrafibrillar remineralization within hybrid layers. The null hypothesis could not be rejected; phosphoric acid esters in dentin adhesives cannot replace PVPA during biomimetic remineralization of adhesive-bonded dentin.     

不同镍钛根管预备系统对牙本质裂纹形成的影响

目的 探讨不同镍钛旋转预备系统ProTaper Universal（PU）、ProTaper Next（PN）和X+File（X+）对牙本质微裂纹形成的影响。方法 将100颗下颌前磨牙随机分为4组（n=25）。组1为对照组（不做根管预备）;组2为PU预备组（SX预备根管口,S1、S2、F1、F2预备直达工作长度）;组3为PN预备组（Protaper Universal SX预备根管口,再用ProTaper Next X1、X2预备直达工作长度）。组4为X+预备组（Protaper Universal SX预备根管口,然后用X+File X1、X2预备直达工作长度）。预备完成后,所有离体牙在距根尖顶点3mm、6mm和9mm处垂直于牙体长轴做横切片,在根管显微镜下观察并记录裂纹形成情况。卡方检验对裂纹形成数目进行统计分析。结果 对照组未产生牙本质裂纹。镍钛旋转系统PU、PN和X+的牙本质裂纹发生率分别为60%,32%和24%（P<0.05）。仅PU组产生完全裂纹,且数目高于另外3组（P<0.05）。在根尖1/3处,PU组的不完全裂纹数高于另外3组（P<0.05）。PN组和X+组的牙本质裂纹发生率无明显差异（P>0.05）。结论 本研究中使用的3种镍钛根管预备系统均产生了牙本质裂纹。其中,X+File与ProTaper Next产生的牙本质裂纹较少,这可能与镍钛金属结构、尖端设计以及中心定位能力有关。     

Distinct decalcification process of dentin by different cariogenic organic acids: Kinetics,ultrastructure and mechanical properties

ObjectivesWe studied artificial dentin lesions in human teeth generated by lactate and acetate buffers (pH 5.0), the two most abundant acids in caries. The objective of this study was to determine differences in mechanical properties, mineral density profiles and ultrastructural variations of two different artificial lesions with the same approximate depth.Methods0.05 M (pH 5.0) acetate or lactate buffer was used to create 1) 180 μm-deep lesions in non-carious human dentin blocks (acetate 130 h; lactate 14days); (2) demineralized, ∼180 μm-thick non-carious dentin discs (3 weeks). We performed nanoindentation to determine mechanical properties across the hydrated lesions, and micro X-ray computed tomography (MicroXCT) to determine mineral profiles. Ultrastructure in lesions was analyzed by TEM/selected area electron diffraction (SAED). Demineralized dentin discs were analyzed by small angle X-ray scattering (SAXS).ResultsDiffusion-dominated demineralization was shown based on the linearity between lesion depths versus the square root of exposure time in either solution, with faster kinetics in acetate buffer. Nanoindentation revealed lactate induced a significantly sharper transition in reduced elastic modulus across the lesions. MicroXCT showed lactate demineralized lesions had swelling and more disorganized matrix structure, whereas acetate lesions had abrupt X-ray absorption near the margin. At the ultrastructural level, TEM showed lactate was more effective in removing minerals from the collagenous matrix, which was confirmed by SAXS analysis.ConclusionsThese findings indicated the different acids yielded lesions with different characteristics that could influence lesion formation resulting in their distinct predominance in different caries activities, and these differences may impact strategies for dentin caries remineralization.     

44Ca doped remineralization study on dentin by isotope microscopy

Objective

The dental caries is developed as a result of an alternative course of mineral gain and loss. In order to distinguish between intrinsic Ca (tooth-derived mineral) and extrinsic Ca (solution-derived mineral) uptakes, a ⁴⁴Ca doped pH-cycling was performed using ⁴⁴Ca (a stable calcium isotope) remineralization solution.

Tensile bond strength of indirect composites luted with three new self-adhesive resin cements to dentin

Objective

The aims of this study were to evaluate the tensile bond strengths between indirect composites and dentin of 3 recently developed self-adhesive resin cements and to determine mode of failure by SEM.

Material and Methods

Exposed dentin surfaces of 70 mandibular third molars were used. Teeth were randomly divided into 7 groups: Group 1 (control group): direct composite resin restoration (Alert) with etch-and-rinse adhesive system (Bond 1 primer/adhesive), Group 2: indirect composite restoration (Estenia) luted with a resin cement (Cement-It) combined with the same etch-and-rinse adhesive, Group 3: direct composite resin restoration with self-etch adhesive system (Nano-Bond), Group 4: indirect composite restoration luted with the resin cement combined with the same self-etch adhesive, Groups 5-7: indirect composite restoration luted with self-adhesive resin cements (RelyX Unicem, Maxcem, and Embrace WetBond, respectively) onto the non-pretreated dentin surfaces. Tensile bond strengths of groups were tested with a universal testing machine at a constant speed of 1 mm/min using a 50 kgf load cell. Results were statistically analyzed by the Student''s t-test. The failure modes of all groups were also evaluated.

Results

The indirect composite restorations luted with the self-adhesive resin cements (groups 5-7) showed better results compared to the other groups (p<0.05). Group 4 showed the weakest bond strength (p>0.05). The surfaces of all debonded specimens showed evidence of both adhesive and cohesive failure.

Conclusion

The new universal self-adhesive resins may be considered an alternative for luting indirect composite restorations onto non-pretreated dentin surfaces.