Indirect Restorative Materials Research Articles

Dental restorative materials and halitosis: a preliminary in-vitro study

Despite the widespread use of dental restorative materials, little information exists in the literature regarding their potential impact on bad breath. This in vitro study aims to fill this gap by investigating the influence of different restorative materials on the release of hydrogen sulfide (H2S). Thirteen diverse dental restorative materials, including composites, flowable composites, glass ionomer restorative materials, high-copper amalgam, and CAD–CAM blocks, were examined. Cellulose Sponge models were used as negative and positive control. All samples were prepared with a diameter of 5 mm and a height of 2 mm. Except for the negative control group, all samples were embedded into Allium cepa L., and the emitted H2S was measured using the Wintact W8802 hydrogen sulfide monitor. Surface roughness’s effect on emission was explored by roughening the surfaces of CAD–CAM material samples, and gas emission was measured again. The data were statistically analyzed using the Kruskal–Wallis test and DSCF pairwise comparison tests. Fiber-reinforced flowable composite (EverX Flow), amalgam (Nova 70-caps), and certain composite materials (IPS Empress Direct, Tetric Evoceram, Admira Fusion X-tra) released higher H2S concentrations compared to the negative control. The H2S release period lasted longer in the same materials mentioned above, along with G-aenial Universal Injectable. Indirectly used materials, such as GC Cerasmart, Vita Enamic, and Vita YZ HT, demonstrated significantly lower emissions compared to other direct restoratives. Importantly, the surface roughness of indirect materials did not significantly affect peak H2S concentrations or release times. The study reveals variations in H2S release among restorative materials, suggesting potential advantages of indirect restorative materials in reducing H2S-induced halitosis. This comprehensive understanding of the relationship between restorative materials and halitosis can empower both dental professionals and patients to make well-informed treatment choices. Notably, there is evidence supporting the enhanced performance of indirect restorative materials for individuals affected by halitosis.

Influence of Immediate Dentin Sealing on Bond Strength of Resin-Based CAD/CAM Restoratives to Dentin: A Systematic Review of In Vitro Studies.

Immediate dentin sealing (IDS) is a method of improving the bond strength of indirect dental restorative materials to dentin and belongs to the biomimetic protocols of contemporary dentistry. The purpose of this systematic review was to evaluate the effect of IDS on the bond strength of resin-based CAD/CAM materials to dentin. PubMed and MEDLINE, Scopus, and the Web of Science were searched by two individual researchers, namely for studies that have been published in English between 1 January 2005 and 31 December 2023 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The inclusion criteria encompassed articles related to in vitro studies, measuring the bond strength through microtensile bond strength (μ-TBS), micro-shear bond strength (μ-SBS), tensile bond strength (TBS) or shear bond strength (SBS) tests after the use of the IDS technique. The included restorative materials comprised resin-based CAD/CAM materials bonded to dentin. A total of 1821 studies were identified, of which 7 met the inclusion criteria. A meta-analysis was not deemed appropriate due to the high level of diversity inthe publications and techniques. The use of IDS yielded higher bond strength outcomesin various experimental conditions and resin-based CAD/CAM materials. Overall, IDS in CAD/CAM restorations may contribute to better clinical outcomesand improved restoration longevity due to this property.

Effect of acidic environment on color and translucency of different indirect restorative materials

PurposeThe aim of the current study was to evaluate the effect of simulated gastric acid on the color and translucency of different indirect restorative materials.Materials and methodsA total of 36 disc-shaped samples were cut by using an isomet saw and divided into four equal groups (n = 9) according to the material type: Group Z: translucent zirconia (Ceramill® Zolid ht.+ preshade, Amann Girrbach, Koblach, Austria); Group E: lithium disilicate (IPS e.max CAD, Ivoclar Vivadent AG, Schaan, Liechtenstein); Group C: resin nanoceramic (Cerasmart, GC, Tokyo, Japan); Group P: polyether ether ketone (PEEK) (Bettin Zirconia Dentale Italy) veneered with indirect high impact polymer composite (HIPC) (breCAM HIPC, Bredent GmbH & Co. KG, Germany). The samples were immersed in simulated gastric acid (HCl, pH 1.2) for 96 hours at 37 °C in an incubator. The color change (ΔE00) and translucency (RTP00) were measured every 9.6 hours (one-year clinical simulation) of immersion in simulated gastric acid.ResultsFor color change (∆E00) and translucency (RTP00) among the tested materials, there was a highly statistically significant difference (P < 0.001) after every year of follow-up. The color change in both Z and G groups was the lowest after 1 year of acid immersion, followed by that in group H, and the highest change in color was recorded in group P.ConclusionHigh translucent zirconia is recommended in patients who are concerned about esthetic, especially with acidic oral environment.

Repair protocols for indirect monolithic restorations: a literature review.

Despite the advancements in indirect monolithic restorations, technical complications may occur during function. To overcome this issues, intraoral repair using resin composite is a practical and low-cost procedure, being able to increase the restoration's longevity. This review aimed to evaluate the need for repair and suggest a standardized repair protocol to the main indirect restorative materials. For this, studies were surveyed from PubMed with no language or date restriction, to investigate the scientific evidence of indirect monolithic restoration repair with direct resin composite. A classification to guide clinical decisions was made based on the FDI World Dental Federation criteria about defective indirect restorations considering esthetic and functional standards, along with the patient's view, to decide when polishing, repairing or replacing a defective restoration. Based on 38 surveyed studies, different resin composite intraoral repair protocols, that included mechanical and chemical aspects, were defined depending on the substrate considering resin-based, glass-ceramic or zirconia restorations. The presented criteria and protocols were developed to guide the clinician's decision-making process regarding defective indirect monolithic restorations, prolonging longevity and increasing clinical success.

Monomer release, cell adhesion, and cell viability of indirect restorative materials manufactured with additive, subtractive, and conventional methods.

The aim of this study was to measure residual monomer, cell adhesion, and cell viability of 3-dimensional printable permanent resin (PR), hybrid ceramic block (HCB), and indirect composite (IC) produced with additive, subtractive, and conventional techniques. Five 8 × 8 × 2 mm3 samples of each material were prepared for each experiment. In a 24-h period, monomer release was analyzed with high-performance liquid chromatography, and cell viability and adhesion were evaluated with the water-soluble tetrazolium salt test. Data were analyzed with IBM SPSS Statistics 26.0 statistical software, and results were regarded as significant at α = 0.05. Monomer release (triethylene glycol dimethacrylate, urethane dimethacrylate, and Bisphenol A glycerolate dimethacrylate) was significantly higher in the IC group. Mean cell viability was significantly lower in the HCB group than in the IC group. All monomers in the tested materials were released at rates that were below clinical significance. Cell adhesion rates in the groups were similar. Cytotoxic response was classified as minor in the HCB and PR groups and non-cytotoxic in the IC group.

Characterization of materials used for 3D printing dental crowns and hybrid prostheses.

To compare the filler weight percentage (wt%), filler and resin composition, flexural strength, modulus, and hardness of several 3D-printed resins to direct and indirect restorative materials. Four 3D-printed resins (C&B MFH, Ceramic Crown, OnX, and OnX Tough), one milled resin composite (Lava Ultimate), one conventional composite (Filtek Supreme), and one ceramic (IPS e.max CAD) were evaluated. Filler wt% was determined by the burned ash technique, and filler particle morphology and composition were analyzed by scanning electron microscopy and energy-dispersive spectroscopy, respectively. Organic resin composition was analyzed by Fourier transform infrared spectroscopy. Three-point bend flexural strength and modulus of the materials were determined by ISO 4049 or ISO 6872. Vickers microhardness was measured. Data were compared with a one-way analysis of variance (ANOVA) and Tukey post hoc analysis. Linear regression analysis was performed for filler wt% versus flexural strength, modulus, and hardness. 3D-printed resins were composed of various sized and shaped silica fillers and various types of methacrylate resins. Significant differences were found among filler wt% with some materials around 3% (C&B MFH), others between 33% and 38% (OnX Tough and OnX), others around 50% (Ceramic Crown), and some around 72% (Filtek Supreme and Lava Ultimate). All 3D-printed resins had significantly lower flexural strength, modulus, and hardness than the conventional and milled resin composites and ceramic material (p < 0.001). Filler wt% demonstrated a linear relationship with modulus (p = 0.013, R2 = 0.821) and hardness (p = 0.018, R2 = 0.787) but not flexural strength (p = 0.056, R2 = 0.551). 3D-printed resins contain from 3% to 50% filler content. Filler wt% alone does not affect flexural strength, but strength may be affected by resin composition as well. Although the 3D-printed resins had lower flexural strength, modulus, and hardness than milled and conventional composite and ceramic, they demonstrated nonbrittle plastic behavior. The properties of 3D-printed resins vary based on their composition, which affects their clinical applications.

Zirconia restoration types, properties, tooth preparation design, and bonding. A narrative review.

The purpose of this review was to provide dental professionals with information regarding the various types of zirconia restorations, their mechanical and optical properties, tooth preparation design, and bonding protocol in an effort to enhance the longevity and durability of zirconia restorations. The yttria content of zirconia ceramics determines their classification. The mechanical and optical properties of each type are discussed, with an emphasis on the effect of yttria concentration on the properties of zirconia. The processing and sintering methods are also discussed as they have a direct impact on the properties of zirconia. The design of tooth preparation, specifically occlusal reduction, varies depending on the type of zirconia used in each case. Finally, a protocol for zirconia restoration bonding is described to ensure optimal bonding to the tooth structure. Not all zirconia restorations are the same. The selection of zirconia type based on yttria concentration, processing and sintering methods, tooth preparation design, and adherence to the bonding protocol are all critical to the success and longevity of zirconia restorations. Zirconia restorations are the most commonly used indirect restorative material. The selection of the most appropriate zirconia type based on its yttria content, which determines its strength and translucency, is critical to the success and the longevity of the restoration. Tooth preparation design also influences the strength and translucency of the zirconia. Air-borne particle abrasion, followed by a ceramic primer and resin cement, can ensure a durable bond to the tooth structure.

Preheated Composite as an Alternative for Bonding Feldspathic and Hybrid Ceramics: A Microshear Bond Strength Study.

To evaluate the bond strength between alternative or conventional luting agents and indirect restorative materials. Blocks of a polymer-infiltrated ceramic network (PICN, Vita Enamic) and a feldspathic ceramic (FEL, Vita Mark II) were sliced and divided according to the luting agent: resin cement (PICN-RC, FEL-RC), flowable composite (PICN-FC, FEL-FC), or preheated composite (PICN-PH, FEL-PH). The ceramic surfaces were polished, etched with 5% hydrofluoric acid for 60 s, and then a silane layer was applied. Cylinders of the luting agents were built up on the ceramic surfaces. In half the samples, the microshear bond strength (µSBS) was tested after 24 h (baseline). The other half was tested after 5000 thermocycles (5°C-55°C) (aging). The failure modes were determined using a stereomicroscope, and the ceramic surfaces were analyzed using a scanning electron microscope. Data were statistically analyzed with two-way ANOVA. Thermocycling reduced the bond strength values of all experimental groups. Regarding FEL, the preheated composite obtained the highest results. Resin cement showed results similar to the flowable composite at baseline and after aging. The highest results of PICN were obtained from the preheated composite followed by resin cement and flowable composite. Significant differences among the three luting agents were observed before and after aging. The most frequent failures among the experimental groups were adhesive and cohesive in the ceramic. Bond strength results indicate that the preheated composite can be an alternative for adhesive cementation when applied on the tested feldspathic ceramic or PICN.

Comparison of Cytotoxicity and Genotoxicity in Three Types of Indirect Restorative Materials on Human Periodontal Stem Cells.

This study aimed to compare the cell toxicity and biological characteristics of Ketac GIC (glass-ionomer cement), Nexus RMGIC (resin-modified glass-ionomer cement), and RelyX RC (resin cement) in human periodontal stem cells (PDSCs). To compare the effects of Ketac GIC, Nexus RMGIC, and RelyX RC on PDSCs, the cements were diluted from 1:2 to 1:8. PDSCs were then treated with the serially diluted cements with or without N-acetyl-cysteine (NAC), and cell survival was measured using water-soluble tetrazolium salt (WST-1) assay. Intracellular reactive oxygen species (ROS) was measured using 2',7'-dichlorofluorescin diacetate (DCFDA), and western blot analysis was performed to observe phosphorylation and activation of extracellular signal-regulated kinase (ERK) by Nexus RMGIC or RelyX RC. Cell death and proliferation were dose-dependently reduced following Nexus RMGIC or RelyX RC treatment. In addition, Nexus RMGIC or RelyX RC showed an increase intracellular ROS generation compared to Ketac GIC. Pretreatment with NAC confirmed the suppression of cell toxicity and ROS generation induced by Nexus RMGIC or RelyX RC. Nexus RMGIC or RelyX RC activates ERK phosphorylation, not p38 phosphorylation, in PDSCs. This study showed that the treatment with Nexus RMGIC or RelyX generates intracellular ROS and cell death through the ERK signaling pathway in PDSCs. In contrast, these effects were not observed with Ketac GIC, indicating that resin-based materials may have cytotoxic and genotoxic effects on PDSCs.

Thermocycling Stain Challenge and Colour Stability of two Current Zirconium Silicate-filled Indirect Composite Restorative Materials

Aim: This study compares the colour stability of two zirconium silicate-filled indirect composite materials CM and its improved formulation CMD using an in vitro thermocycling stain challenge model with 2 immersion solutions. The rationale of the thermocycling stain challenge model is to replicate the intraoral conditions that the indirect composite materials may be exposed to during a clinical service, water or saliva absorption and cyclical exposure to staining food colourant at varying temperature extremes. Materials and Methods: Ten discs each from shade A1 subtypes of CM and CMD indirect composites (Dentine Body A1B, Incisal 58, and Translucent HVT) were subjected to a thermocycling stain challenge following final polishing, which consisted of static immersion in 37°C of distilled water, followed by 500 thermocycles in 5°C of tea and 55°C of soy sauce and finally a 10-minute cleaning using an ultrasonic device. L*, a* and b* colour coordinates were measured, and the mean colour difference expressed as Delta E (ΔE) at different time points of the experiment were calculated and compared. Results: CM and CMD indirect composites had a significant color difference at all experimental time points (F=37.818, p&lt;0.001). ΔE for CM subtypes and CMD subtypes in descending order, respectively, were Translucent HVT&gt;Incisal 58&gt;Dentin Body A1B and Incisal 58&gt;Translucent HVT&gt;Dentin Body A1B. Conclusion: CMD indirect composite showed improved colour stability compared to CM indirect composite. Clinical Significance: Limiting the usage of translucent shades and polishing according to the manufacturer’s recommendation may improve the overall colour of prostheses made using indirect zirconium silicate-filled composite materials.

Evaluation of shade matching in the repair of indirect restorative materials with universal shade composites.

To evaluate color differences in repair of indirect ceramic and resin nanoceramic CAD/CAM blocks with two universal shade composites after different surface preparations. 120 samples were prepared from IPS Empress and GC Cerasmart270 CAD/ CAM blocks and thermocycled (5000 cycles, 5°C-55°C). Initial colors of sample surfaces were measured using a spectrophotometer. Rectangular prism-shaped cavities were prepared and repaired with Tokuyama Universal Bond/Omnichroma and G-Multiprimer/G-Premio/Essentia Universal following surface preparation with aluminum oxide, Cojet, and bioactive glass (Sylc). Repaired samples were thermocycled (5000 cycles) and color measurement was performed. Color coordinates L*a*b* were recorded, and color differences were calculated using the CIELab formula. Color differences between pre-and post-repair (ΔE1) and between post-repair and post-aging (ΔE2) were determined. Data were analyzed using Three-way ANOVA with a significance level set at p<0.05. ΔE1 values in all subgroups exceeded the threshold of 3.3. No significant difference was found between the surface preparation processes regarding ΔE1 values. There was no significant difference between the composites and bonding agents in ΔE1 values, except for Cerasmart/Sylc and Empress/Sylc groups. No statistically significant difference was detected in ΔE2 values between the surface preparation treatments in all groups. (p >0.05). Color match of the universal shade composites, which are preferred to increase the esthetic satisfaction and to simplify repair procedures, were found above the acceptable threshold. Post-aging color stability of universal shade composites was below the acceptable threshold.

Indirect restorative systems-A narrative review.

The background and clinical understanding of the properties of currently available indirect restorative systems and fabrication methods is, along with manufacturer and evidence-based literature, an important starting point to guide the clinical selection of materials for tooth and/or implant supported reconstructions. Therefore, this review explores most indirect restorative systems available in the market, especially all-ceramic, along with aspects of manufacturing process, clinical survival rates, and esthetic outcomes. Progressive incorporation of new technologies in the dental field and advancements in materials science have enabled the development/improvement of indirect restorative systems and treatment concepts in oral rehabilitation, resulting in reliable and predictable workflows and successful esthetic and functional outcomes. Indirect restorative systems have evolved from metal ceramics and polymers to glass ceramics, polycrystalline ceramics, and resin-matrix ceramics, aiming to improve not only biological and mechanical properties, but especially the optical properties and esthetic quality of the reconstructions, in attempt to mimic natural teeth. Based on several clinical research, materials, and patient-related parameters, a decision tree for the selection of indirect restorative materials was suggested to guide clinicians in the rehabilitation process. The pace of materials development is faster than that of clinical research aimed to support their use. Since no single material provides an ideal solution to every case, professionals must continuously seek information from well designed, long-term clinical trials in order to incorporate or not new materials and technological advancements.

The Longevity and Clinical Performance of Direct and Indirect Restorations, Including Amalgam, Composite, Ceramic, and Metal Restorations

The longevity of dental restorations depends on patient-related, dentist-related, and material-related factors. Patientrelated factors include restoration size, chewing habits, oral hygiene, and systemic conditions. Strength, wear resistance, water tolerance, dimensional stability, and colour stability are all material-related variables. When deciding on a course of treatment, dentists must take these things into account. Since the 19th century, dental amalgam, which is composed of mercury, silver, tin, copper, and other metals, has been used effectively. Although it has limits in terms of tooth colour matching, it is appropriate for Class I and II restorations. Amalgam offers good load-bearing qualities, wear resistance, and tolerance for various clinical conditions. Safety concerns include the release of mercury vapor and the possibility of localized allergic reactions. Resin-based composites are esthetic and safe materials used for anterior and small to moderate-sized posterior fillings. Postoperative tooth sensitivity and shrinkage-related issues can occur, but improvements have minimized these problems. Adequate field control is essential for successful placement. Indirect restorative materials include all-ceramic and base metal casting alloys. All-ceramic restorations provide excellent aesthetics, high strength, and biocompatibility. However, they rely on resin-based cements and adhesives for retention, and allergies can occur. Base metal alloys offer an economical alternative and are effective for crown-and-bridge restorations. The choice of restorative materials depends on various factors, and dentists must consider the specific needs of each patient to achieve successful outcomes.

Comparison of Two Different Electro Polish Temperature on Cobalt Ion Release of Chromium Cobalt Alloy in Artificial Saliva with Atomic Absorption Spectrophotometry

Introduction: Metals are widely used in direct and indirect restorative materials, both in prosthetics and orthodontics. The biocompatibility of these metals depends on their chemical nature, the number of ions released, and the period of contact of these metals. This study aims to compare two different electropolish temperatures on the release of cobalt ion from chromium-cobalt alloy.&#x0D; Materials &amp; Methods: In this experimental study, 24 wax patterns were cut in the form of a circle with a diameter of 15 mm and a thickness of 1 mm. Then, the samples were sprued and invested. Burn out and casting were used to cast the alloy. The samples were sandblasted and polished with aluminum oxide. They were randomly divided into two 12-number groups and electropolished at 45° and 55° C. Samples were placed in artificial saliva and sent to atomic absorption spectrophotometer for 15 and 30 days to read the cobalt. Data were then analyzed by Independent t-test and Paired t-test (p value = 0.05).&#x0D; Results: The average release of cobalt from chromium cobalt alloy on the 30th day was higher than the 15th day at both 45°C and 55°C. This difference was significant at 45°C (p value = 0.036) while not significant at 55°C (p value = 0.0754). Regarding the comparison of the ion release at 45° and 55°C, the difference was not significant on the 15th day (p value = 0.067) and 30th day (p value = 0.0754).&#x0D; Conclusion: The amount of cobalt ions released from the cobalt-chromium alloy at 45°C is fewer than at 55°C over time.&#x0D;

Overview of Lithium Disilicate as a restorative material in dentistry

Lithium disilicate was first introduced to the dental field as an indirect restorative material in 1998. It was marketed under the name IPS Empress 2, and was intended for use with press technology. It was later replaced by modified versions including IPS e.max® Press and IPS e.max® CAD. Newer versions have since emerged,namely Amber Mill GC Initial and CEREC Tesseratwo.The latter has part crystal composition of lithium disilicate,embedded in a glassy zirconia matrix. The CAD versionis provided in a meta-silicate state, characterised by40% platelet-shaped lithium meta-silicate crystals and aglassy matrix that is bluish in colour. To obtain the desired lithium disilicate structure and tooth shades, a process ofcrystallization is required. This involves firing at 840 °C,for 25 minutes. The resulting glass-ceramic material has the benefit of providing maximum aesthetic translucency along with good fracture resistance of about 2MPa, and mechanical strength of 360MPa. Developments in the all-ceramic dental materials have led to improvements in their physical properties and aesthetic appeal, leading to a substantial increase in their clinical use. This paper present a review of lithium disilicate with particular reference to its chemical composition, aesthetic versatility, and durability for use in crowns, veneers, and implant retained restorations. It also covers the recommended techniques prescribed to ensure predictable bonding and cementation. An electronic literature search on the use of lithium disilicate in dentistry was carried out using EBSCOhost search engine. This included all papers relating to its use for conventional veneers, crowns and bridge work, for CAD/CAM restorations, dentine bonding procedures and luting agents. It covered all papers published in peer reviewed journals from 1988 to 2021. The review indicates that lithium disilicate can be a useful and versatile material in dentistry providing it is handled correctly and the recommended tooth and restoration surface preparations and bonding procedures are carried out. The latter involves tooth etching and silane treatment of the fitting surfaces of restorations prior to cementation to improve adhesion and fracture resistance.

Surface characterization of indirect restorative materials submitted to different etching protocols

ObjectivesThis in vitro study aimed to evaluate the effect of different times and concentrations of hydrofluoric acid etching on the surface of indirect restorative materials obtained from blocks used in CAD-CAM technology. MethodsSpecimens (4 mm × 4 mm × 0.8 mm) were obtained for each indirect restorative material: zirconia-reinforced lithium monosilicate ceramic (Celtra Duo), nanoceramic resin (Lava Ultimate), and polymer-infiltrated ceramic network material (Vita Enamic). The materials were submitted to etching with 5% or 10% hydrofluoric acid for 20, 40, 60, or 90 s. A control group for each material was evaluated without any surface treatment, totaling nine experimental groups for each material (n = 10). The specimens were evaluated for surface roughness (Ra and Rz), confocal optical microscopy, the contact angle (θ), surface free energy (γs), total free interaction energy (∆G) using a goniometer, and microshear bond strength to resin cement. Specimen images were obtained using scanning electron microscopy, confocal optical microscopy, and atomic force microscopy. Data on the surface roughness, the contact angle, surface free energy, total free interaction energy, and bond strength were subjected to two-way ANOVA and Tukey´s test (α=0.05). ResultsIn general, Celtra Duo showed better results after etching with 10% hydrofluoric acid for 40 or 60 s. Lava Ultimate showed better performance after etching with 10% hydrofluoric acid for 20 or 40 s, whereas Vita Enamic showed better results after etching with 5% hydrofluoric acid for 90 s. ConclusionEach material showed different characteristics after etching with hydrofluoric acid. Knowledge of the proper protocol for each material is essential to ensure improvements in the adhesion process and durability of indirect restorations. In general, Celtra Duo presented mechanical properties superior to those of Lava Ultimate and Vita Enamic. Clinical SignificanceSpecific etching protocols must be recommended for each indirect material because longer exposure to hydrofluoric acid can jeopardize the surface, thus affecting the mechanical and bond strength properties.

The effect of periodontal prophylaxis procedures on the surface properties of tooth-colored restorative materials

This study aimed to investigate the effect of various periodontal hygiene procedures on the surface properties of direct and indirect restorative materials. Disc-shaped specimens (10 × 2 mm) of FC: Flowable Composite, UC: Universal Composite, IC: Indirect Composite, CC: CAD/CAM Composite were fabricated (n = 70) and divided randomly into subgroups: 1-Control, 2-US: Ultrasonic scaling, 3-RP: Rubber-cup polishing, 4-AP: Air-polishing, 5-US+RP, 6-US+AP, 7-US+AP+RP. The color, surface roughness, and gloss measurements were performed. Data were analyzed with variance analysis and the correlation coefficient was used to evaluate the relationship between surface properties (p < 0.05). The highest and lowest roughness values were obtained in FC after US and CC’s control group, respectively. The surface roughness of FC, IC, and CC was significantly affected by the application of various prophylaxis procedures (p < 0.05). AP and US+AP+RP presented the least and most affected surface roughness, respectively. The lowest surface gloss value was in the US and RP subgroups of FC. The process that the least reduced the surface gloss was AP. Material and procedure affected the color stability (p < 0.05) except for CC. The highest ΔE values were obtained in US+AP+RP subgroups. Indirect restorative materials showed less roughness and color change as well as higher gloss values after all periodontal prophylaxis procedures. The use of air-polishing has proven to be a reliable periodontal hygiene approach for direct and indirect restorations due to the less deterioration in the surface properties.

Finite element analysis and nanomechanical properties of composite and ceramic dental onlays

The aim is to evaluate the mechanical properties of the composite and ceramic based indirect restorative materials used in dental treatments with scanning nanoindentation test (NT). Finite element analysis (FEA) was applied to investigate the stress distribution. Four hybrid composite materials; Indirect resin composite (IRC), Resin nanoceramic (RNC), Polymer infiltrated ceramic (PIC) and Zirconia-reinforced lithium-di-silicate (ZRC) were divided into two subgroups for NT (n = 20) and fracture test (n = 40). Statistical analyses were performed with independent t-test, ANOVA and post-hoc Tukey tests (p ≤ 0.05). The highest hardness, elasticity and fracture toughness were observed in ZRC (p = 0.001). Frequency of vertical root fractures in RNC and IRC were statistically lower than ZRC (p = 0.032). Reinforced CAD-CAM ceramics revealed higher mechanical properties compared with IRC materials. The FEA model for fracture mechanism of RNC demonstrated lowest stress values and uniform stress distribution amongst all groups, while ZRC and PIC presented the highest fracture toughness.

Effect of Acidic Solutions on the Surface Roughness and Microhardness of Indirect Restorative Materials: A Systematic Review and Meta-analysis

To evaluate the effects of acidic solutions on the surface roughness (SR) and surface microhardness (SMH) of indirect restorative materials by analyzing in vivo and in vitro studies. Studies comparing the SR and SMH of indirect restorative materials after erosion were included in the meta-analysis. Meta-analyses were conducted with a random-effects model at a significance level of P < .05 using Review Manager software (Cochrane Collaboration). The literature search was conducted using Web of Science, MEDLINE (PubMed), and the Cochrane Library, with no limitations on publication year. Of the 1,097 potentially relevant studies, 32 full-text articles were assessed for eligibility. A total of 16 articles were included in the systematic review, and 15 were included in the meta-analyses. The kappa score between the two reviewers was 0.80. The effects of erosion on ceramics, indirect composites, and hybrid ceramics were evaluated by immersion in or rinsing with acidic solutions (eg, hydrochloric acid [HCl], cola drinks, and juices). An increase in the SR (Ra values) (P < .00001; mean difference [MD] = -0.04; 95% CI = -0.06 to -0.03) and a decrease in the SMH (Vickers microhardness) (P < .00001; MD = 13.94; 95% CI = 12.33 to 15.55) were found after erosion. Subgroup analyses revealed that in vitro erosion led to significantly higher Ra values and lower VHN values than in vivo erosion; cola drinks and juices led to more surface degradation than HCl; and the SR and SMH of polymer-infiltrated ceramic network (PICN) materials remained unchanged after erosion. After acidic challenges, a significantly rougher and softened surface was found for indirect restorative materials. Among all the indirect restorative materials, PICN showed the best acid resistance. Nevertheless, the changes in the SR and SMH of indirect restorative materials after erosion detected in the present study were minor and may not have any clinical significance.

25 - Analysis of Indirect Restorative Materials Submitted to Different Conditioning Protocols

The aim of this study was to evaluate the influence of hydrofluoric acid application time and concentration on bond strength and surface morphology of three indirect restorative materials. Samples measuring 4x4x0.8 mm were obtained from three materials (lithium monosilicate reinforced by zirconia - Celtra Duo, nanoceramic resin - Lava Ultimate and hybrid ceramic - Vita Enamic). These materials were conditioned with hydrofluoric acid at concentrations of 5% or 10% for 20, 40, 60 or 90 seconds. In addition, a control group was adopted, in which no conditioning was performed, totaling 9 groups for each material. The analysis of bond strength was performed using the microshear test (n=6). For this purpose, cylinders of Variolink Esthetic LC resin cement were made on the conditioned samples, using a silicone matrix. The test was performed in a mechanical testing equipment, in which the samples were fixed and with the aid of an orthodontic wire, tension was applied to the cylinders. Bond strength data were submitted to two-way ANOVA and Tukey's test (α=0.05). The surface microstructure of each material was observed through images obtained by the technique of scanning electron microscopy (SEM) (n=2). Celtra Duo presented better bond strength values when subjected to etching with 10% hydrofluoric acid for 40, 60 and 90 seconds. For Lava Ultimate, better results were obtained with application of 10% acid concentration for 20 and 40 s, while Vita Enamic showed better results after application of 5% hydrofluoric acid for 40 and 90 seconds and at 10% for 20 and 40 s. Through the images obtained by the technique of scanning electron microscopy (SEM) it was possible to observe the appearance of irregularities on the surface of each material evaluated after conditioning. The evaluated restorative materials showed different behaviors after conditioning protocols with hydrofluoric acid, therefore, the professional must adopt the best hydrofluoric acid concentration and time protocol for each specific material in order to obtain a satisfactory and effective adhesive procedures.