Zirconia-reinforced lithium silicate (ZLS) mechanical and biological properties: A literature review

Objectives: This paper aimed to provide a literature review of the mechanical and biological properties of zirconia-reinforced lithium silicate glass-ceramics (ZLS) in Computer-aided design / Computer-aided manufacturing (CAD/CAM) systems.Data/Sources: An extensive search of the literature for papers related to ZLS was made on the databases of PubMed/Medline, Scopus, Embase, Google Scholar, Dynamed, and Open Grey. The papers were selected by 3 independent calibrated reviewers.Study selection: The search strategy produced 937 records. After the removal of duplicates and the exclusion of papers that did not meet the inclusion criteria, 71 papers were included.Conclusions: After reviewing the included records, it was found that two types of ZLS (Vita Suprinity PC; Vita Zahnfabrik and Celtra Duo; Dentsply Sirona) are nowadays available on the market for CAD/CAM systems, similar in their chemical composition, microstructure, and biological-mechanical properties. ZLS is reported to be a biocompatible material, whose fracture resistance can withstand physiological chewing loads. The firing process influences the improvements of strength and fatigue failure load, with a volumetric shrinkage. To date, ZLS can be considered a viable alternative to other glass-ceramics for fixed single restorations. Clinical Significance: . As to biocompatibility and mechanical properties of ZLS, data are still scarce, often controversial and limited to short-term observational periods. These promising ceramics require further in vitro/ in vivo studies to accurately define mechanical and biological properties, mainly in the long-term performance of restorations produced with such materials

The effect of chlorhexidine primer application on the clinical performance of composite restorations: a literature review

AbstractTo discuss the effectiveness of chlorhexidine (CHX) used as therapeutic dentin primer in adhesively bonded composite restorations.OverviewAn electronic search in MEDLINE database, accessed through PubMed was conducted. No restrictions of languages and date of publication were made. The following key words were used: "chlorhexidine", "composite" and "composite resins." Clinical studies in which CHX was used during bonding procedures were included in this review. Six studies met the inclusion criteria. Of these, five studies were carried out on noncarious cervical lesions (NCCL). Only one study was carried out on class II preparation of permanent molars. In all studies, either etch‐and‐rinse and self‐etch adhesive systems were used during bonding procedures. On the basis of the reviewed clinical trials, it can be concluded that CHX primer application does not seem to influence clinical outcome of composite restorations.Clinical significanceCurrent scientific evidence cannot neither strongly recommend nor discourage the application of CHX as therapeutic primer in composite restorations. Studies with longer follow‐up periods with adhesive restorations placed on dentin after caries removal, rather than only on NCCL, are desirable to further investigate the therapeutic effect of CHX during bonding procedures

Quality of veiled olive oil: Role of turbidity components

This study investigated the effects of water and content of solid particles, taken together as well as separately, on stability of veiled olive oil. The following oil samples were obtained through four different separation treatments: veiled, filtered, \u2018solid-only\u2019, and \u2018water-only\u2019. Changes in chemical, microbial, and sensory characteristics were evaluated during storage (240 days). A significant effect of hydrolysis was shown in veiled and \u2018water only\u2019 oils; in \u2018solid-only\u2019 oils, a slow increase of phenols was observed. A notable microbial activity, with resulting formation of volatile metabolites and sensory defects, was observed in veiled samples. Filtered oils underwent less significant changes

Effect of Different Artificial Staining Procedures on the Color Stability and Translucency of a Nano-Hybrid Resin-Based Composite

Background: To evaluate the effect of different experimental staining procedures on color stability and translucency of a nano-hybrid resin-based composite (RBC). Methods: Forty-eight cylindrical-shaped specimens (10 x 2 mm) were prepared with a nano-hybrid RBC (Clearfil Majesty ES-2) and randomly divided in four groups according to the experimental staining procedure: G1) static immersion in a staining solution (coffee) (44 +/- 1 degrees C); G2) staining cycling between coffee (44 +/- 1 degrees C) and distilled water (37 +/- 1 degrees C) with an experimental staining machine based on Arduino, an Open Source hardware development platform; G3) staining cycles as in G2 + brushing with a low abrasive toothpaste (Relative Dentin Abrasion RDA = 30) (Elmex Sensitive Professional); G4) staining cycles as in G3, with brushing performed with a very strong abrasive toothpaste (RDA = 90) (Lacult Active). Color parameters were recorded at the baseline (T0) after staining procedures (T1) and repolishing (T2) using a spectrophotometer. Color change ( increment E00) and translucency (TP, CR) were evaluated. Data were statistically analyzed (p < 0.05). Results: For increment E00 after staining, Group 1 showed the highest color change and Group 3 the lowest. All groups were significantly different (p < 0.001) except for Group 2 vs. Group 4; after repolishing, Group 1 was significantly higher than Group 3 (p < 0.001), Group 2 (p < 0.001), and Group 4 (p = 0.003); Group 2 was higher than Group 3 (p < 0.001). For TP variable, after staining procedures, Group 2 was significantly higher than all other groups (p < 0.001), and Group 1 was significantly higher than Group 3 (p < 0.001) and Group 4 (p = 0.007). After repolishing, Group 4 was significantly lower than Group 3 (p = 0.008) and Group 2 (p = 0.027). Repolishing procedure significantly reduced color parameters. Conclusions: The investigated staining procedure induced significant differences in color stability and translucency. The use of a very strong abrasive toothpaste (RDA = 90) induced higher color change than a low abrasive one (RDA = 30). Repolishing procedures are able to partially reduce color change induced by artificial staining procedures

Structurally compromised teeth. Part II: A novel approach to peripheral build up procedures

ObjectiveTo introduce the "Peripheral Build-Up technique - PBUt" as a foundation restoration strategy for structurally compromised teeth (SCT). Clinical ConsiderationsSeveral strategies have been proposed over time (cervical marginal relocation, doughnut, and preformed ring techniques) to enable the management of restorative procedures in challenging situations such as the presence of deep subgingival defects. The PBUt is a versatile, completely additive direct technique that share some strategical concepts with these techniques to approach critical clinical situations while supplying a wider field of application thanks to distinct operative expedients. The clamp insertion modality, the extension of the proximal wall and the matrix customization/stabilization strategies adopted in PBUt endorse the possibility to manage the most apical and peripheral border of the residual tooth structure when located up to >1.5 mm above the bone crest. The periodontal response has to be then monitored over time. Moreover, thanks to the peripheral and apically-extended addictive approach, it allows a massive preservation of residual sound tooth structure and improves the resistance and retentive physical/geometrical features of the abutment tooth. The PBUt operative workflow is herein explained. Clinical SignificanceThe Peripheral-Build-Up technique (PBUt) advocates some innovative clinical restorative steps for the management of SCT with coronal and deep subgingival defects

Effect of shelf-life of a universal adhesive to dentin

The microtensile bond strength (\u3bcTBS), nanoleakage expression (NL), and endogenous enzymatic activity of a simplified universal adhesive system used in combination with a dual-cure resin cement for luting indirect restorations were evaluated considering its shelf-life (as-received vs expired). The universal adhesive was used asreceived (AS-R) by manufacturer or after three months after being expired (EXP). Resin composite overlays (n \ubc 10) were luted to flat deep coronal dentin surfaces with a universal bonding system (iBond universal, used in the self-etch mode) in combination with a dual-cure resin cement (RelyX Ultimate; 20s of light-cure followed by 15 min of self-cure at 37 \ufffdC). After 24 h, the specimens were cut into microtensile sticks (1 mm2) and stressed to failure under tension, in accordance with ISO/TS 11.405. The fracture pattern was evaluated with optical microscopy. The significance level of p \ubc 0.05 was used for the statistical analysis. Additional specimens (n \ubc 4) were processed for quantitative interfacial nanoleakage expression using ammoniacal silver nitrate. To investigate the endogenous enzymatic activity within the hybrid layer in situ zymography was performed. The EXP group obtained significantly lower \u3bcTBS values than those recorded in the AS-R group (p < 0.05). NL resulted in higher deposition of AgNO3 granules when the adhesive was used in the EXP group compared to the AS-R bonding system. In situ zymography assay revealed increased level of fluorescence when the universal bonding system was used at the end of shelf-life compared to the AS-R group. The use of the universal adhesive system beyond the expiry limit resulted in decreased bonding performances. Furthermore, the higher endogenous enzymatic activity recorded after the end of the shelf life of the universal adhesive would portend for a shortened durability of the restorations

Optical behaviors, surface treatment, adhesion, and clinical indications of zirconia-reinforced lithium silicate (ZLS): A narrative review

Objectives: The present narrative review was focused on the optical properties, surface treatment, adhesion, and clinical indications of zirconia-reinforced lithium silicate ceramics (ZLS) for Computer-aided design / Computer-aided manufacturing (CAD/CAM) technologies. Data/sources: A literature search was performed by 3 calibrated independent researchers on PubMed, Scopus, Embase, Google Scholar, Dynamed, and Open Grey. The criteria for inclusion were: 1) papers addressing at least one of the following variables about ZLS: optical properties, surface treatment, adhesion, and clinical indications; 2) in vitro, in silico, or in vivo studies; 3) case reports; 4) systematic reviews. The exclusion criteria were: 1) animal studies; 2) non-dental studies; 3) studies only focusing on ZLS used in the heat-pressed process. Study selection: 98 records among in vitro studies and case reports were included. Conclusions: Despite the promising microstructure characteristics of ZLS, increased translucency compared to lithium disilicate ceramics (LS2) was not proven, but acceptable color changes and stability were reported. Mechanical polishing was the most effective method to reduce surface roughness. Moreover, machinability and handling of ZLS resulted harder than LS2. Conventional acid etching procedures seemed effective in conditioning ZLS surface, but no protocol has been established yet. Besides, silane-coupling and dual-curing resin cements were recommended. Clinical significance: ZLSs can be used for anterior and posterior fixed single-unit CAD/CAM restorations onto both natural teeth and implants, but do not seem to represent a viable treatment option for endocrowns onto posterior teeth or fixed dental prostheses

Resin composite cements: Current status and a novel classification proposal

ObjectivesCurrently, a classification of resin cements that includes relatively recently formulated ("universal") cements is lacking. Furthermore, the terminology used to define different resin cements in the scientific reports is inconsistent. Accordingly, this work aims to: (i) propose a novel classification of resin composite cements; (ii) disambiguate the term "universal cements" and (iii) present an overview of the properties of these cements. MethodsAn analysis of peer-reviewed literature (PubMed search), as well as market research on definitive resin composite cements were performed. ResultsA tendency toward simplified and versatile luting materials was observed both in the scientific literature and on the dental market with the advent of self-adhesive/one-step resin cements. However, additional priming procedures were necessary to improve their bonding performance in certain clinical situations. Hence, several cements that can be applied both in adhesive and self-adhesive mode were introduced. These cements are associated with a universal adhesive resin, that can be used as a tooth and/or restorative material primer, without the need for other priming systems, regardless of the substrate. These systems should be considered truly universal. Therefore, we hereby suggested a new classification of resin-based cements: (1) adhesive/multi-step; (2) self-adhesive/one-step; (3) universal cements (one- or multi-step). Despite promising in vitro results, clinical trials and long-track laboratory studies are necessary to confirm the reliability of the universal cements. ConclusionsThis review presented the current advances in the field of resin-based cements, which are reflected in the proposed classification. The term "universal cement" was disambiguated, which will help standardize the terminology used in published research. Clinical SignificanceThe classification of resin-based cements and a better understanding of the proper terminology will help standardize the terminology in published research, as well as improve the understanding of the clinical practitioners of the different indications and possible modalities of use of the available cements

Selective adhesive luting: A novel technique for improving adhesion achieved by universal resin cements

Objective: We aimed to introduce the concept of "Selective adhesive luting-SAL" which is explained through clinical steps and supported by preliminary laboratory evidence. Clinical considerations: Cementation with rubber dam is difficult to perform in case of short abutment teeth and/or subgingival crown margins. By means of universal resin cements/universal adhesive systems, which can be employed in self-adhesive as well as adhesive luting procedures, this paper presents a novel technique allowing clinicians to perform reliable cementation where rubber dam isolation is difficult. The SAL technique entails the application of a universal adhesive system only on easily accessible abutment surfaces, enabling simultaneous adhesive and self-adhesive luting in different portions of the abutment. The SAL clinical workflow is explained through prosthodontic rehabilitation of maxillary right central incisor affected by microdontia and restored with a lithium-disilicate crown. Furthermore, our laboratory microshear bond strength study supports the rationale behind SAL application demonstrating higher bond strength even when the adhesive resin is placed only on one portion of the cementation substrate. Clinical significance: This article advocates the application of SAL technique in clinical situations where effective adhesive luting is uncertain, since it can improve the adhesion between the tooth and universal resin cements