Adhesión a dentina parte I: características del sustrato y sistemas adhesivos / Dentin bonding part I: substrate characteristics and bonding systems

La Odontología Restauradora contemporánea no puede concebirse sin la adhesión de los materiales restauradores a las estructuras dentarias. En mu-chos procedimientos restauradores, no sólo el esmal-te sino también la dentina se encuentra involucrada, por lo tanto, la adhesión a esta última juega un rol cla-ve en el éxito clínico. No obstante, todavía supone un gran desafío lograr una adhesión estable y predeci-ble en el tiempo. El propósito del presente artículo es analizar las características principales de la dentina como sustrato adhesivo y describir los sistemas ad-hesivos actuales y sus mecanismos de acción (AU)

Contemporary Restorative Dentistry cannot be conceived without the adhesion of restorative materials to dental structures. In many restorative procedures not only the enamel, but also the dentin is involved, therefore dentin bonding plays a key role in their success. However, it is still a great challenge to achieve stable and predictable dentin bonding over time. The aim of this article is to analyze the main characteristics of dentin as an adhesive substrate and to describe current adhesive systems and their bonding mechanisms (AU)

Flow Cytometry Analysis of Antibacterial Effects of Universal Dentin Bonding Agents on Streptococcus mutans.

There is no consensus on the antibacterial activity of dentin bonding systems (DBS). Many study models have been used to evaluate the antimicrobial activity of dental materials. In this study, a novel detection method, flow cytometry, was introduced. It allows for evaluation of the antibacterial activity of DBS, based on assessment of the disruption of the bacterial physical membrane induced by DBS. The aim of the study was to evaluate the antibacterial properties of selected dentin bonding systems against Streptococcus mutans. The highest antibacterial activity against S. mutans was observed for Adhese Universal (99.68% dead cells) and was comparable to that of Prime&Bond Universal, OptiBond Universal, or Clearfil Universal Bond Quick (p > 0.05). The lowest activity of all tested systems was displayed by the multi-mode adhesive, Universal Bond (12.68% dead bacteria cells), followed by the self-etch adhesive, OptiBond FL (15.58% dead bacteria cells). The present study showed that in the case of two-component DBS, the primer exhibited higher antimicrobial activity than the adhesive (or bond) itself.

[Curing mode of universal adhesives affects the bond strength of resin cements to dentin].

OBJECTIVE: To determine the effects of curing mode of one-step and two-step universal adhesives on the micro-tensile bond strength (µTBS) of different dual-cure resin cements to dentin. METHODS: One-step universal adhesive Single Bond Universal (SBU), and two-step universal adhesive OptiBond Versa (VSA) were chosen as the subjects, one-step self-etching adhesive OptiBond All in One (AIO) and two-step self-etching adhesive Clearfil SE Bond (SEB) were control groups, and two dual-cure resin cements RelyX Ultimate (RLX) and Nexus 3 Universal (NX3) were used in this study. In this study, 80 extracted human molars were selected and the dentin surface was exposed using diamond saw. The teeth were divided into 16 groups according to the adhesives (AIO, SBU, SEB, VSA), cure modes of adhesives (light cure, non-light cure) and resin cements (RLX, NX3). The adhesives were applied on the dentin surface following the instruction and whether light cured or not, then the resin cements were applied on the adhesives with 1 mm thickness and light cured (650 mW/cm(2) for 20 s. A resin was built up (5 mm) on the cements and light cured layer by layer. After water storage for 24 h, the specimens were cut into resin-cement-dentin strips with a cross sectional area of 1 mm×1 mm and the µTBS was measured. RESULTS: Regarding one-step universal adhesive (SBU) light cured, the µTBS with RLX [(35.45±7.04) MPa] or NX3 [(26.84±10.39) MPa] were higher than SBU non-light cured with RLX [(17.93±8.93) MPa)] or NX3 [(10.07±5.89) MPa, P<0.001]. Compared with AIO, light-cured SBU combined with RLX presented higher µTBS than AIO group [(35.45±7.04) MPa vs. (24.86±8.42) MPa, P<0.05]. When SBU was not lighted, the µTBS was lower than AIO [(17.93±8.93) MPa vs. (22.28±7.57) MPa, P<0.05]. For two-step universal adhesive (VSA) and control adhesive (SEB), curing mode did not affect the µTBS when used with either RLX or NX3 (25.98-32.24 MPa, P>0.05). CONCLUSION: Curing mode of one-step universal adhesive may affect the µTBS between dual-cure resin cements and dentin, while for two-step universal adhesive, the curing mode and the type of resin cements did not influence the µTBS.

Defying ageing: An expectation for dentine bonding with universal adhesives?

OBJECTIVES: The present study evaluated the long-term dentine bonding effectiveness of five universal adhesives in etch-and-rinse or self-etch mode after 12 months of water-ageing. METHODS: The adhesives evaluated included All-Bond Universal, Clearfil Universal Bond, Futurabond U Prime&Bond Elect and Scotchbond Universal. Microtensile bond strength and transmission electron microscopy of the resin-dentine interfaces created in human coronal dentine were examined after 24h or 12 months. RESULTS: Microtensile bond strength were significantly affected by bonding strategy (etch-and-rinse vs self-etch) and ageing (24h vs 12 months). All subgroups showed significantly decreased bond strength after ageing except for Prime&Bond Elect and Scotchbond Universal used in self-etch mode. All five adhesives employed in etch-and-rinse mode exhibited ultrastructural features characteristic of collagen degradation and resin hydrolysis. A previously-unobserved inside-out collagen degradation pattern was identified in hybrid layers created by 10-MDP containing adhesives (All-Bond Universal, Scotchbond Universal and Clearfil Universal Bond) in the etch-and-rinse mode, producing partially degraded collagen fibrils with intact periphery and a hollow core. In the self-etch mode, all adhesives except for Prime&Bond Elect exhibited degradation of the collagen fibrils along the thin hybrid layers. The three 10-MDP containing universal adhesives did not protect surface collagen fibrils from degradation when bonding was performed in the self-etch mode. CONCLUSIONS: Despite the adjunctive conclusion that bonds created by universal adhesives in the self-etch bonding mode are more resistant to decline in bond strength when compared with those bonds created using the etch-and-rinse mode, bonds created by universal adhesives are generally incapable of defying ageing.

Adhesive sealing of dentin surfaces in vitro: A review.

PURPOSE: This review describes the evolution of the use of dental adhesives to form a tight seal of freshly prepared dentin to protect the pulp from bacterial products, during the time between crown preparation and final cementation of full crowns. The evolution of these "immediate dentin sealants" follows the evolution of dental adhesives, in general. That is, they began with multiple-step, etch-and-rinse adhesives, and then switched to the use of simplified adhesives. METHODS: Literature was reviewed for evidence that bacteria or bacterial products diffusing across dentin can irritate pulpal tissues before and after smear layer removal. Smear layers can be solubilized by plaque organisms within 7-10 days if they are directly exposed to oral fluids. It is likely that smear layers covered by temporary restorations may last more than 1 month. As long as smear layers remain in place, they can partially seal dentin. Thus, many in vitro studies evaluating the sealing ability of adhesive resins use smear layer-covered dentin as a reference condition. Surprisingly, many adhesives do not seal dentin as well as do smear layers. RESULTS: Both in vitro and in vivo studies show that resin- covered dentin allows dentin fluid to cross polymerized resins. The use of simplified single bottle adhesives to seal dentin was a step backwards. Currently, most authorities use either 3-step adhesives such as Scotchbond Multi-Purpose or OptiBond FL or two-step self-etching primer adhesives, such as Clearfil SE, Unifil Bond or AdheSE.

Adhesión a tejidos dentarios / Bonding to dental tissues

En las últimas décadas, la odontología restauradora ha logrado un avance significativo que permite preservar tejido dentario mediante la realización de restauraciones adheridas, directas e indirectas. Este enfoque moderno de “Odontología Mínimamente Invasiva”, se centra en obtener preparaciones dentarias con un diseño más conservador, basándose en la eficacia de la adhesión al tejido remanente de los biomateriales utilizados. El conocimiento de las características de los sustratos y de los materiales adhesivos, y la comprensión del mecanismo de adhesión es un factor fundamental para alcanzar el éxito clínico...

Self-etch and etch-and-rinse adhesive systems in clinical dentistry.

Current adhesive systems follow either an "etch-and-rinse" or "self-etch" approach, which differ in how they interact with natural tooth structures. Etch-and-rinse systems comprise phosphoric acid to pretreat the dental hard tissues before rinsing and subsequent application of an adhesive. Self-etch adhesives contain acidic monomers, which etch and prime the tooth simultaneously. Etch-and-rinse adhesives are offered as two- or three-step systems, depending on whether primer and bonding are separate or combined in a single bottle. Similarly, self-etch adhesives are available as one- or two-step systems. Both etch-and-rinse and self-etch systems form a hybrid layer as a result of resins impregnating the porous enamel or dentin. Despite current trends toward fewer and simpler clinical application steps, one-step dentin bonding systems exhibit bonding agent lower bond strengths and seem less predictable than multi-step etch-and-rinse and self-etch systems. The varying evidence available today suggests that the choice between etch-and-rinse and self-etch systems is often a matter of personal preference. In general, however, phosphoric acid creates a more pronounced and retentive etching pattern in enamel. Therefore, etch-and-rinse bonding systems are often preferred for indirect restorations and when large areas of enamel are still present. Conversely, self-etch adhesives provide superior and more predictable bond strength to dentin and are, consequently, recommended for direct composite resin restorations, especially when predominantly supported by dentin.

Bonding performance of a newly developed step-less all-in-one system on dentin.

The purpose of this study was to evaluate the short-term µTBS (Micro-tensile bond strength) and microscopic (SEM and TEM) observation of four recent adhesives. One adhesive was an experimental step-less 1-step system (LLB-2, Tokuyama Dental), which is an all-in-one system without the light-curing step in the application process. The other two were self-adhering light-cured flowable composite resin systems FLD (Fusio Liquid Dentin, Pentron Clinical Technologies) and VF (Vertise Flow Dental Restorative Materials, Kerr Corporation), which combine all the bonding steps together. A 2-step self-etching system MG (Clearfil MegaBond, Kuarary Medical) was employed as the control group in this study. The µTBS of MG was the highest (79.0 MPa) followed by that of LLB-2 (63.1 MPa), FLD (23.6 MPa), and VF (13.1 MPa). The microscopic observations showed that MG and LLB-2 had an approximately 20 µm and 5 µm adhesive layer respectively, without bubble or gap-formation at the resin-dentin interface, which were found in FLD and VF.

Adhesives for the restoration of non-carious cervical lesions: a systematic review.

OBJECTIVES: To establish whether simplified adhesives (self-etch) are as clinically effective as conventional adhesives (etch-and-rinse) with multiple application steps for treatment of non-carious cervical lesions (NCCLs). NULL HYPOTHESIS: there is no difference in the clinical effectiveness of the four different bonding strategies: Three-step etch-and-rinse; Two-step etch-and-rinse; Two-step self-etch; One-step self-etch for treatment of NCCLs. SOURCES: Electronic databases were searched including: Cochrane Oral Health Group Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE and EMBASE. In addition, studies were identified by handsearching of selected journals. STUDY SELECTION: Randomised controlled trials (RCTs) comparing at least two adhesives in non-carious cervical lesions (NCCLs), with at least 18 months follow-up were selected. The primary outcome was loss of retention/restoration loss, with marginal adaptation and marginal discolouration as secondary outcomes. Criteria for quality assessment included: random sequence generation; allocation concealment; blinding of outcome assessment; and information on withdrawals. Twenty six studies were identified that met the inclusion criteria. In general, studies were not of sufficient quality to fully address the objectives of this review. CONCLUSION: There is not enough evidence to support one adhesive or bonding strategy over another for treatment of NCCLs. Consequently, the null hypothesis of no difference cannot be supported or rejected with the data currently available. There is a need for better standardisation and reporting of randomised controlled trials investigating adhesive performance. CLINICAL SIGNIFICANCE: Studies with low overall risk of bias demonstrated good clinical performance for adhesives with all four bonding strategies. However, included studies showed wide variation between adhesives of the same category.

Shear bond strength of seventh generation bonding agents on dentin of primary teeth--an in vitro study.

This controlled, randomized, in vitro study evaluated the shear bond strength of several seventh generation bonding agents on the dentin of primary teeth. Six different adhesives were used: Xeno IV, Clearfil S3 Bond, Adper Prompt-L-Pop, AdheSE One, Bond Force, and Optibond (control). Ninety primary teeth were prepared by wet grinding with a 320-grit silicon carbide paper on a polishing wheel running at 110 RPM. After 24 hours of storage in water, shear bond strengths of each group were determined. The mean shear bond strength of the tested adhesive systems to primary dentin was 12.27 MPa. One-way ANOVA testing showed a statistically significant difference between adhesive products (P < 0.001). Tukey HSD post hoc tests were used to assess which means were significantly different from one another. There was no statistically significant difference between the fifth generation adhesive system (Optibond) and the two seventh generation systems (Xeno IV and Bond Force), with Optibond exhibiting a lower mean shear bond strength compared to Bond Force. Within the limitations of this study, there is a significant difference between seventh generation bonding materials. Bond Force and Optibond appear to exhibit higher shear bond strengths than the other products.

Meta-analytical review of parameters involved in dentin bonding.

Bond-strength testing is the method most used for the assessment of bonding effectiveness to enamel and dentin. We aimed to disclose general trends in adhesive performance by collecting dentin bond-strength data systematically. The PubMed and EMBASE databases were used to identify 2,157 bond-strength tests in 298 papers. Most used was the micro-tensile test, which appeared to have a larger discriminative power than the traditional macro-shear test. Because of the huge variability in dentin bond-strength data and the high number of co-variables, a neural network statistical model was constructed. Variables like 'research group' and 'adhesive brand' appeared most determining. Weighted means derived from this analysis confirmed the high sensitivity of current adhesive approaches (especially of all-in-one adhesives) to long-term water-storage and substrate variability.

Adhesive systems: important aspects related to their composition and clinical use.

This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and influence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classified according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-and-rinse systems require a specific acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and deficiencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplified ones due to some chemical associations and interactions. The SEM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions.

Adhesive systems: important aspects related to their composition and clinical use

This literature review article addresses the types and the main components of different etch-and-rinse and self-etch adhesive systems available in the market, and relates them to their function, possible chemical interactions and infuence of handling characteristics. Scanning electron microscopy (SEM) images are presented to characterize the interface between adhesives and dentin. Adhesive systems have been recently classifed according to their adhesion approaches in etch-and-rinse, self-etch and glass ionomer. The etch-and-rinse systems require a specifc acid-etch procedure and may be performed in two or three steps. Self-etch systems employ acidic monomers that demineralize and impregnate dental substrates almost at the same time. These systems are separated in one or two steps. Some advantages and defciencies were noted for etch-and-rinse and self-etch approaches, mainly for the simplifed ones due to some chemical associations and interactions. The SEM micrographs illustrate different relationships between adhesive systems and dental structures, particularly dentin. The knowledge of composition, characteristics and mechanisms of adhesion of each adhesive system is of fundamental importance to permit the adoption of ideal bonding strategies under clinical conditions.

Enamel bonding of single-step self-etch adhesives: influence of surface energy characteristics.

OBJECTIVES: This study examined the surface free energy of enamel treated with the single-step self-etching adhesives Bond Force, Clearfil tri-S Bond and G-Bond. METHODS: The labial enamel surfaces of bovine mandibular incisors were wet ground with #180-grit, #600-grit and #2000-grit silicon carbide paper. The adhesives were applied to the ground enamel, and then rinsed with acetone and distilled water. The surface free energies were determined by measuring the contact angles of three test liquids placed on the adhesive-treated enamel. The data for each adhesive system were analyzed using analysis of variance and Tukey's honestly significant difference test. RESULTS: The surface free energies of the samples treated with the G-Bond and tri-S Bond adhesives increased as the surface roughness decreased. No significant differences in the surface free energy were found for the samples treated with the Bond Force adhesive regardless of the surface roughness. CONCLUSION: The results indicated that the surface free energies and their components of the treated enamel surfaces were different among the adhesive systems used.

In vitro evaluation of bonding effectiveness to dentin of all-in-one adhesives.

OBJECTIVES: The study was aimed at assessing the bonding potential of all-in-one adhesives to dentin. METHODS: The microtensile bond strength of the all-in-one adhesives Bond Force (Tokuyama), AdheSE One (Ivoclar-Vivadent), and Xeno V (Dentsply) was measured in comparison with the etch-and-rinse system XP Bond (Dentsply). The ultrastructural characteristics of dentin-adhesive interface were observed under scanning electron microscope (SEM). Twenty human extracted third molars had their mid-coronal dentin exposed and ground with wet 600-grit SiC paper in order to create a standardized smear layer. Bonding procedures were performed according to the manufacturers' instructions and microtensile beams were obtained with the "non-trimming" technique. The bond strengths in MPa were statistically analyzed including pre-test failures as "zero" values (Kolmogorov-Smirnov test, Levene's test, One-Way ANOVA, Tukey's test p<0.05). RESULTS: The following bond strengths were recorded in MPa (mean+/-standard deviation): AdheSE One 31.7+/-21.3; Xeno V 42.8+/-26.4; Bond Force 43.3+/-22.1; XP Bond 51.9+/-18.6. The statistical analysis demonstrated that the bond strengths achieved by Bond Force and Xeno V were similar to that of the etch-and-rinse adhesive, whereas the bond strength of AdheSE One was significantly lower. A distinct hybrid layer with resin tags was seen only in XP Bond specimens. All-in-one adhesives demonstrated a rather superficial interaction with the dentin substrate. CONCLUSIONS: Although the strongest bond to dentin was established by the etch-and-rinse system, however the all-in-one adhesives containing organic solvents reached bond strength levels that were comparable from a statistical point of view.

Microleakage of ceramic inlays luted with different resin cements and dentin adhesives.

STATEMENT OF PROBLEM: Despite recent advances in adhesive dentistry, resin cement/dentin adhesive combinations are not able to prevent microleakage in ceramic inlays. Marginal quality of tooth-colored restorations in large Class II cavities is satisfactory in enamel margins, but microleakage in dentin margins remains a concern. PURPOSE: The purpose of this study was to evaluate the microleakage of all-ceramic inlays luted with 2 dual-polymerizing resin cements or 1 autopolymerizing resin cement in combination with different dentin adhesives. MATERIAL AND METHODS: One hundred and twenty extracted human mandibular third molars were used in this study. Teeth were prepared to receive Class II MOD inlays with enamel gingival margins on 1 proximal surface and dentin gingival margins on the other surface. One hundred and twenty prepared teeth were divided into 3 groups of 40; 1 group for each resin cement: RelyX ARC, Variolink II, or Panavia 21. Each of the 3 groups were further divided into 4 dentin adhesive groups; Single Bond, ExciTE DSC, ED Primer, or Admira Bond. Each of the resin cements were used in combination with the 4 dentin adhesives, and IPS Empress ceramic inlays were placed with 12 different cement/adhesive combinations. After 1000 thermal cycles in a 5 degrees -55 degrees C water bath with a dwell time of 30 seconds, all specimens were subjected to cyclic axial mechanical loading. Then the restored teeth were stored in 0.5% basic fuchsin solution for 24 hours. The extent of dye penetration along the margins was measured with a stereomicroscope at x40 magnification. The data were evaluated statistically using repeated-measures ANOVA and Duncan tests (alpha=.05). RESULTS: Microleakage at dentin margins was greater than that at enamel margins (P<.05) for all groups. Variolink II and RelyX ARC resin cements showed significantly lower microleakage results than Panavia 21 with all dentin adhesives in enamel margins. For dentin margins, Variolink II/Admira Bond combination showed the lowest microleakage value in dentin (P<.05). CONCLUSIONS: The overall microleakage at the enamel margins was significantly less than at the dentin margins (P<.05). Panavia 21 showed higher microleakage values than Variolink II and RelyX ARC in enamel margins.

Micro-shear bond strength of current one-step adhesives to cementum and dentin.

PURPOSE: To investigate the bonding performance of current one-step adhesives to human cementum and compare the results with those of two-step adhesives. METHODS: Four commercially available adhesives were investigated: two one-step adhesives (Clearfil Tri-S Bond and G-Bond), and two two-step adhesives: a self-etch adhesive (Clearfil SE Bond) and a total-etch wet bonding adhesive (Adper Single Bond). The cementum and dentin regions were chosen from the mesial surface of extracted human molars and bonded with each adhesive. A micro-shear bond test was employed to evaluate the bond strength in this study. Morphological micrographs of cementum and dentin after etching, as well as bonded interfaces were obtained using scanning electron microscopy. RESULTS: The shear bond test results showed significantly lower bonding of all adhesives when they were applied to cementum (P < 0.05). The mean bond strength values in MPa obtained from dentin and cementum were 33.7 and 26.7 for Clearfil Tri-S Bond, 28.9 and 22.4 for G-Bond, 42.9 and 35.2 for Clearfil SE Bond and 38.6 and 32.5 for Adper Single Bond, respectively. One-step adhesives showed significantly lower bond strengths than two-step adhesives to both cementum and dentin (P < 0.05).