Progress in Dental Adhesive Materials Cadenaro, M.; Josic, U.; Maravić, T. ...
Journal of Dental Research,
03/2023, Letnik:
102, Številka:
3
Book Review, Journal Article
Recenzirano
There have been significant advances in adhesive dentistry in recent decades, with efforts being made to improve the mechanical and bonding properties of resin-based dental adhesive materials. ...Various attempts have been made to achieve versatility, introducing functional monomers and silanes into the materials’ composition to enable the chemical reaction with tooth structure and restorative materials and a multimode use. The novel adhesive materials also tend to be simpler in terms of clinical use, requiring reduced number of steps, making them less technique sensitive. However, these materials must also be reliable and have a long-lasting bond with different substrates. In order to fulfill these arduous tasks, different chemical constituents and different techniques are continuously being developed and introduced into dental adhesive materials. This critical review aims to discuss the concepts behind novel monomers, bioactive molecules, and alternative techniques recently implemented in adhesive dentistry. Incorporating monomers that are more resistant to hydrolytic degradation and functional monomers that enhance the micromechanical retention and improve chemical interactions between adhesive resin materials and various substrates improved the performance of adhesive materials. The current trend is to blend bioactive molecules into adhesive materials to enhance the mechanical properties and prevent endogenous enzymatic degradation of the dental substrate, thus ensuring the longevity of resin–dentin bonds. Moreover, alternative etching materials and techniques have been developed to address the drawbacks of phosphoric acid dentin etching. Altogether, we are witnessing a dynamic era in adhesive dentistry, with advancements aiming to bring us closer to simple and reliable bonding. However, simplification and novelty should not be achieved at the expense of material properties.
Resin cement diffusion into dentin may differ as a function of the pre-treatment regimen. Since self-adhesive cements do not require substrate pre-treatment for luting, penetration of and interaction ...with the underlying dentin are questioned. We hypothesized that differences in the resin cement diffusion into dentin may exist among current commercial adhesive cements. Composite cylinders were luted on mid-coronal dentinal surfaces by an etch-and-rinse cement (Calibra), a self-etching system (Panavia F 2.0), and 4 self-adhesive cements (Multilink Sprint, Rely X Unicem, G-Cem, Bis-Cem). Dentin/cement interfacial characteristics were analyzed by a staining technique (Masson’s trichrome) and by scanning electron microscopy. Conventional acid etching resulted in partially infiltrated adhesive interfaces differing from those achieved with the application of self-etching primer. No hybrid layer and/or resin tag formation was detectable at the interfaces bonded with self-adhesive cements. Limited decalcification/infiltration was observed for self-adhesive cements into the underlying dentin. Self-adhesive cements were not able to demineralize/dissolve the smear layer completely.
To evaluate the effects of microorganisms’ contamination inside the dispensing syringes of different types of resin-based composites (RBCs).
This study encompassed two sections. First, an anonymous ...electronic survey was submitted via Google forms to Italian dentists to acquire information about composite handling during clinical procedures. Then, a bench test was performed on nanohybrid RBCs differing in matrix chemistry and fillers FiltekTM Supreme XTE (3MTM); Venus Pearl (Kulzer GmbH); Admira Fusion x-tra (Voco) to evaluate the microbial viability on their surfaces with/out photocuring. Uncured RBCs were exposed to standardized inocula of Streptococcus Mutans, Candida Albicans, Lactobacillus Rhamnosus, or mixt plaque in an in vitro model reproducing clinical restorative procedures. Half of the RBC specimens were cured after exposure. Microbial viability was assessed using an MTT-based test. Statistical analysis included three-way ANOVA and Tukey's tests (p<0.05).
Among 300 dentists completing the survey, the majority declared to use the spatula to carry the RBCs from the syringe to the dental cavity (50% same spatula; 35% two spatulas). However, 80% of respondents had personal feelings that using one spatula could be a source of cross-contamination. In vitro results using one spatula showed microbial contamination of all RBCs after one hour of storage. The contamination levels depended on the used strain and RBC type (p<0.0001), but photocuring did not reduce contamination (p = 0.2992).
Microbial species’ viability on uncured RBCs and after photocuring shows the existence of a considerable risk of cross-infection. Clinical procedures in Restorative Dentistry need to acknowledge and to reduce such risk during RBCs handling.
Dentists must be aware of the possibility of cross-infection during restorative procedures, especially when the same spatula is repeatedly used for placing RBC in the cavity.
Carbodiimide (EDC)–based dentin primers preserve hybrid layer (HL) integrity. However, aging >1 y has not been investigated. The present study examined whether the cross-linking effect of EDC was ...reflected in dentin bond strength, endogenous enzymatic activity, and the chemical profile of the HL after 5-y aging in artificial saliva. Noncarious human third molars (N = 42) were cut to expose middle/deep coronal dentin and treated as follows: group 1, dentin etched with 35% H3PO4, pretreated with a 0.3M aqueous EDC primer for 1 min and restored with XP Bond (Dentsply Sirona); group 2, as in group 1 but without EDC pretreatment; group 3, Clearfil SE Bond (Kuraray-Noritake) primer applied to dentin surface, followed by EDC pretreatment as in group 1 and application of bond; group 4, as in group 3 without EDC pretreatment. After composite buildup, the specimens were cut into sticks or slabs, depending on the experiment. All tests were performed at baseline (T0) and after 5 y of aging (T5) in artificial saliva at 37 °C. Microtensile bond strength (µTBS) was tested at a crosshead speed of 1 mm/min until failure. Endogenous enzymatic activity was investigated with in situ zymography. The chemical profile of HL was determined via Raman spectroscopy. Three-way analysis of variance and post hoc Tukey test were used to analyze µTBS and in situ zymography data (α = 0.05). EDC pretreatment and aging significantly influenced µTBS and in situ zymography results (P < 0.05). Higher bond strength and lower gelatinolytic activity were identified in the EDC-treated groups at T5 (P < 0.05), especially in the etch-and-rinse groups. Raman spectra revealed less defined amide III peaks in control specimens at T5. The EDC cross-linking effect persisted in the HL for 5 y in terms of bond strength, collagen structure preservation, and dentinal enzyme silencing.
The chemo-mechanical surface treatment of fiber posts increases their bonding properties. The combined use of atomic force and confocal microscopy allows for the assessment and quantification of the ...changes on surface roughness that justify this behavior. Quartz fiber posts were conditioned with different chemicals, as well as by sandblasting, and by an industrial silicate/silane coating. We analyzed post surfaces by atomic force microscopy, recording average roughness (Ra) measurements of fibers and resin matrix. A confocal image profiler allowed for the quantitative assessment of the average superficial roughness (Ra). Hydrofluoric acid, potassium permanganate, sodium ethoxide, and sandblasting increased post surface roughness. Modifications of the epoxy resin matrix occurred after the surface pre-treatments. Hydrofluoric acid affected the superficial texture of quartz fibers. Surface-conditioning procedures that selectively react with the epoxy-resin matrix of the fiber post enhance roughness and improve the surface area available for adhesion by creating micro-retentive spaces without affecting the post’s inner structure.
New zirconia ceramics obtained from blanks having interpenetrating layers with different mechanical and optical properties (yttria gradient concept) have been developed to improve the restoration ...strength without impairing the optical properties; the aim of this study is to evaluate the translucency of crowns made with Katana YML (Yttria Multi-Layered) comparing them to other monolithic restorations.
A.stl file was used to obtain 60 crowns (1.5mm thickness, shade: A2 VITA) with one of the following materials (n=10): 1) Katana Zirconia YML, ultra-rapid sintering (URS, Kuraray-Noritake); 2) 88 ZB PRO (8853S.p.A.); 3) Explore GT-M (Lispning-UpCera); 4) IPS e.max ZirCAD (Ivoclar); 5) Katana Zirconia YML, long sintering cycle (LS); 6) Avencia Block LT, hybrid ceramic (Kuraray). Each crown was checked for external and internal defects under transillumination, weighed to ascertain the accuracy and repeatability and finally polished using Katana Zirconia Twist Dia rubber-wheels. The following methods were used to assess crown translucency: a) Total Transmission, using both white D65 light (TTW) and blue light (TTB) @405 -468 nm peaks (Cybird Gold lamp, DXM): the light (Lx) passing through the crowns was determined as a percentage of the original flow (integrating sphere: Everfine AAIS-2-0.3M; photoradiometer: L100, PCE); b) Contrast ratio, by alternately putting the crowns on a white and black substrate: a colorimeter (Easy-Color, Smart-Vision) was used to calculate the translucency parameter (TP). Data were statistically analyzed (alpha=0.05).
Within TP analysis, YML URS showed the highest translucency among zirconia crowns, inferior only to Avencia hybrid ceramic; however, when analyzed with TTW and TTB, 88ZB and e.max ZirCAD showed slightly higher (~10%) translucency values. When comparing TTW and TTB translucency, a reduction of the residual blue light flow percentage was observed in all groups, although not significant in 88ZB and e.max ZirCAD (P>0.075); the other groups showed a significant drop (p<0.001) of the permeability to blue light. The YML LS displayed the lowest translucency among groups, irrespective of the test used.
The translucency of Katana YML ultra-rapid sintering proved to be higher or similar to the other ceramic and hybrid ceramic materials, depending on the evaluation method. The YML URS permeability to blue curing light was moderately lower (7,83%) in comparison to the value obtained with white light. Katana YML seemed sensible to the sintering technology: when processed with ultra-rapid sintering the restorations were significantly more translucent than the one subjected to long sintering cycle.
This study investigated the composite-to-composite microtensile bond strength and interfacial quality after using different combinations of intermediate agents and pre-curing temperatures of ...repairing resin. Forty-five composite discs (8x4 mm) of Gradia Direct Anterior (GC Corp), stored in a saline solution at 37 degrees C for one month, were sandblasted (50 microm aluminum oxide), cleaned (35% phosphoric acid) and randomly divided into three groups (n=15) according to the intermediate agent applied: (1) no treatment; (2) unfilled resin (Scotchbond Multi-Purpose Adhesive, 3M ESPE); (3) flowable composite (Gradia LoFlo, GC Corp). Each disc was incrementally repaired (8x8 mm) with the same resin as the substrate. For each group, three subgroups (n=5) were created, depending on the pre-curing temperature of the repairing resin-4 degrees C, 23 degrees C or 37 degrees C. Two bonded specimens per group were prepared to evaluate the composite-to-composite interfacial quality via scanning electron microscope. Microtensile bond strength measurements were performed with the remaining three specimens and failure mode was examined by stereomicroscopy. Two-way ANOVA revealed that temperature (p < 0.001), intermediate agent (p < 0.001) and the interaction (p = 0.002) significantly affected the repair strength. Post-hoc comparisons revealed that bond strengths were significantly lower using a 4 degrees C repairing resin in groups where intermediate agents were used. The highest bond strengths were recorded when flowable composite was used as an intermediate agent under each of the three temperature conditions. Interfacial quality improved by raising the resin temperature from 4 degrees C to 37 degrees C.
To evaluate the effects of two SDF dentin surface pre-treatments on bond strength and endogenous enzymatic activity (MMPs) of a simplified universal adhesive at baseline and after 1 year of ...artificial aging.
The middle/deep and enamel/free coronal dentin of 60 sound human molars was exposed. The following groups were formed, according to the dentin surface pre-treatment and etching mode of the universal adhesive (Zipbond, SDI; ZB) used for bonding procedures (n=10): 1) ZB applied in the self-etch mode (SE); 2) Riva Star (R) + SE (RSE); 3) Riva Star Aqua (A) + SE (ASE); 4) ZB applied in the total-etch mode (TE); 5) R + TE (RTE); 6) A + TE (ATE). After 24h, specimens were cut to obtain 1-mm2 thick sticks. The microtensile bond strength (µTBS) test was performed at baseline (T0) and after 1 year (T12) of storage in artificial saliva at 37°C and 100% relative humidity. Fractography analysis of debonded specimens was performed with a scanning electron microscope (SEM). To investigate the effect of SDF on MMPs activity, 3 additional molars per group were processed for the in situ zymography analysis at T0 and T12. Data were statistically analyzed (p<0.05).
Dentin pre-treatment, etching mode, aging and their interactions significantly influenced the bond strength (p T12 (p0.05).
Bonding performances and endogenous enzymatic activity were influenced by pre-treatment with SDF solutions, although the use of Riva Star Aqua showed long term MMPs inhibitory effects comparable to the control groups. Further studies are warranted to validate these results.
