Polymer-infiltrated Ceramic Network Research Articles

Intraoral wear of PICN CAD-CAM composite restorations used in severe tooth wear treatment: 5-year results of a prospective clinical study using 3D profilometry.

To evaluate, in a prospective clinical study over 5 years with ex vivo 3D profilometry analyses, the intraoral wear of Polymer-Infiltrated Ceramic Network (PICN) CAD-CAM composite restorations used in severe tooth wear treatment with the One-Step No-Prep technique. 192 PICN (Vita Enamic) restorations on molars and premolars were included in a prospective clinical study involving patients treated according to the One-step No-prep protocol (n=7). All patients showed clinical signs of bruxism. Replicas of restorations on molars and premolars were realized at each evaluation time (baseline and then every year up to 5 years) and scanned to perform 3D profilometry. Baseline and recall scans were superimposed with Geomagic Control software. The mean material wear was calculated for the full occlusal area (FOA) and for the occlusal contact area (OCA), respectively. Clinical evaluation of restorations was performed at recall. At 5 years, the estimated mean material wear for FOA was inferior to the accuracy threshold of the profilometry measurement chain. For OCA, the estimated mean wear of the material was - 27.97µm. This material wear was shown to be significantly influenced by time (p<0.0001) and patient (p=0.026), while the type of tooth (molar or premolar) had no influence. At 5 years, the survival and the success rates of restorations were 99.48% and 90.62%, respectively. The PICN material exhibits a low wear process in the treatment of severe tooth wear despite the presence of clinical signs of bruxism, and it constitutes a suitable material for the One-step No-prep technique.

Static and dynamic stress analysis of different crown materials on a titanium base abutment in an implant-supported single crown: a 3D finite element analysis

BackgroundThis Finite Element Analysis was conducted to analyze the biomechanical behaviors of titanium base abutments and several crown materials with respect to fatigue lifetime and stress distribution in implants and prosthetic components.MethodsFive distinct designs of implant-supported single crowns were modeled, including a polyetheretherketone (PEEK), polymer-infiltrated ceramic network, monolithic lithium disilicate, and precrystallized and crystallized zirconia-reinforced lithium silicates supported by a titanium base abutment. For the static load, a 100 N oblique load was applied to the buccal incline of the palatal cusp of the maxillary right first premolar. The dynamic load was applied in the same way as in static loading with a frequency of 1 Hz. The principal stresses in the peripheral bone as well as the von Mises stresses and fatigue strength of the implants, abutments, prosthetic screws, and crowns were assessed.ResultsAll of the models had comparable von Mises stress values from the implants and abutments, as well as comparable maximum and minimum principal stress values from the cortical and trabecular bones. The PEEK crown showed the lowest stress (46.89 MPa) in the cervical region. The prosthetic screws and implants exhibited the highest von Mises stress among the models. The lithium disilicate crown model had approximately 9.5 times more cycles to fatique values for implants and 1.7 times more cycles to fatique values for abutments than for the lowest ones.ConclusionsWith the promise of at least ten years of clinical success and favorable stress distributions in implants and prosthetic components, clinicians can suggest using an implant-supported lithium disilicate crown with a titanium base abutment.

Fracture resistance and failure mode of three esthetic CAD-CAM post and core restorations

BackgroundThe rising demand for improved aesthetics has driven the utilization of recently introduced aesthetic materials for creating custom post and core restorations. However, information regarding the fracture resistance of these materials remains unclear, which limits their practical use as custom post and core restorations in clinical applications.Aim of the studyThis study aimed to evaluate the fracture resistance of three non-metallic esthetic post and core restorations and their modes of failure.Materials and methodsThirty-nine single-rooted human maxillary central incisors were endodontically treated. A standardized post space preparation of 9mm length was performed to all teeth to receive custom-made post and core restorations. The prepared teeth were randomly allocated to receive a post and core restoration made of one of the following materials (n=13): glass fiber-reinforced composite (FRC), polyetheretherketone (PEEK) and polymer-infiltrated ceramic-network (PICN). An intraoral scanner was used to scan all teeth including the post spaces. Computer-aided design and computer-aided manufacturing (CAD-CAM) was used to fabricate post and core restorations. Post and core restorations were cemented using self-adhesive resin cement. All specimens were subjected to fracture resistance testing using a universal testing machine. Failure mode analysis was assessed using a stereomicroscope and SEM. The data was statistically analyzed using One-Way ANOVA test followed by multiple pairwise comparisons using Bonferroni adjusted significance level.ResultsCustom PEEK post and core restorations displayed the least fracture load values at 286.16 ± 67.09 N. In contrast, FRC exhibited the highest average fracture load at 452.60 ± 105.90 N, closely followed by PICN at 426.76 ± 77.99 N. In terms of failure modes, 46.2% of specimens with PICN were deemed non-restorable, while for PEEK and FRC, these percentages were 58.8% and 61.5%, respectively.ConclusionsWithin the limitation of this study, both FRC and PICN demonstrated good performance regarding fracture resistance, surpassing that of PEEK.

Investigation of Mechanical Properties of Polymer-Infiltrated Tetrapodal Zinc Oxide in Different Variants.

The aim of this study was to evaluate the influence of weight ratio, the shape of the precursor particles, and the application of a phosphate-monomer-containing primer on the mechanical properties of polymer infiltrated ceramic networks (PICNs) using zinc oxide. Two different types of zinc oxide particles were used as precursors to produce zinc oxide networks by sintering, each with two different densities resulting in two different weight ratios of the PICNs. For each of these different networks, two subgroups were built: one involving the application of a phosphate-monomer-containing primer prior to the infiltration of Bis-GMA/TEGDMA and one without. Elastic modulus and flexural strength were determined by using the three-point bending test. Vertical substance loss determined by the chewing simulation was evaluated with a laser scanning microscope. There was a statistically significant influence of the type of precursor particles on the flexural strength and in some cases on the elastic modulus. The application of a primer lead to a significant increase in the flexural strength and in most cases also in the elastic modulus. A higher weight ratio of zinc oxide led to a significantly higher elastic modulus. Few statistically significant differences were found for the vertical substance loss. By varying the shape of the particles and the weight fraction of zinc oxide, the mechanical properties of the investigated PICN can be controlled. The use of a phosphate-monomer-containing primer strengthens the bond between the infiltrated polymer and the zinc oxide, thus increasing the strength of the composite.

Comparison of Treatment Time for Single-Implant Crowns Between Digital and Conventional Workflows for Posterior Implant Restorations: A Randomized Controlled Trial.

To compare the treatment time of digital and conventional workflows for single-implant crowns, as well as prostheses made of polymer-infiltrated ceramic-network (PICN; Vita Enamic, Vita Zahnfabrik) and lithium disilicate (LS2; n!ce, Straumann). A total of 40 patients who needed a single-implant crown in posterior regions were considered and randomly divided into digital workflows (n = 20) that used an intraoral scanner (IOS; iTero Element 5D, Align Technologies) and conventional workflows (n = 20) that used polyether impressions (3M ESPE Impregum Penta). Then, each group was again distributed into two subgroups based on the crown material used: PICN (n = 10) and LS2 (n = 10). Treatment time was calculated for both digital and conventional workflows. Analysis was done at a 5% confidence interval (P < .05). An independent two-sample t test was used to compare treatment time between the groups. The Kruskal-Wallis test was used to compare clinical try-in time among subgroups. Any of the implant crowns that had to be remade in each subgroup were evaluated using the Fisher exact test. The entire process of digital and conventional workflows required 104.31 ± 20.83 and 153.48 ± 16.35 minutes, respectively. Digital workflows saved 39.2% more time than the conventional protocol for the single-implant crown treatment (P < .0001). Both digital and conventional workflow protocols can achieve a successful outcome for single-implant monolithic crowns in posterior areas. The digital protocol yielded greater timesaving over the conventional procedure in data acquisition and laboratory steps, while the time for clinical try-in and delivery were similar.

Long-Term Bonding Efficacy of CAD/CAM Hybrid Restorative Materials and Universal Adhesives.

In-office and lab milled prostheses are the staple for indirect restorations. It is therefore critical to determine their long-term bonding durability. CAD/ CAM blocks of two classes of restorative materials: 1) a nano-ceramic reinforced polymer matrix (NCPM) and, 2) a polymer-infiltrated ceramic network (PICN) were bonded using four different universal adhesives (UA) and silane systems. A lithium disilicate glassceramic (LDS) was used as a reference. The blocks were bisected and bonded with different UA/resin-cement pairs. Bonded blocks were then cut into 1.0x1.0x12.0 mm bar specimens for microtensile bond testing. Half the bars were subjected to bond strength testing immediately and the other half after aging by 50,000 thermal cycles between 5°C and 55°C. ANOVA and post-hoc tests were used to compare mean bond strength among groups. NCPM presented consistently high bond strength regardless of bonding techniques, while the bond strength of PICN and LDS were lower when bonded with UA relative to traditional silanes. The more hydrophilic UA produced higher bond strengths. Glass-ceramics exhibited lower bond strength with UA than the conventional etch-rinse-silane techniques. However, UAs preserved bonding interface in the long-term. NCPM displayed superior bond strength relative to PICN and LDS regardless of the type of adhesives and bonding techniques.

Polymer-Infiltrated Ceramic Network Produced by Direct Ink Writing: The Effects of Manufacturing Design on Mechanical Properties

Polymer-infiltrated ceramic network (PICN) materials have gained considerable attention as tooth-restorative materials due to their mechanical compatibility with human teeth, especially with computer-aided design and computer-aided manufacturing (CAD/CAM) technologies. However, the designed geometry affects the mechanical properties of PICN materials. This study aims to study the relationship between manufacturing geometry and mechanical properties. In doing so, zirconia-based PICN materials with different geometries were fabricated using a direct ink-writing process, followed by copolymer infiltration. Comprehensive analyses of the microstructure and structural properties of zirconia scaffolds, as well as PICN materials, were performed. The mechanical properties were assessed through compression testing and digital image correlation analysis. The results revealed that the compression strength of PICN pieces was significantly higher than the respective zirconia scaffolds without polymer infiltration. In addition, two geometries (C-grid 0 and C-grid 45) have the highest mechanical performance.

Bonding Pretreatment of Aesthetic Dental CAD-CAM Materials through Surface Etching with a Mixed Aqueous Solution of Ammonium Fluoride and Ammonium Hydrogen Sulfate.

Hydrofluoric acid (HF) is commonly used as an etchant for the pretreatment of dental computer-aided design/computer-aided manufacturing (CAD-CAM) materials, such as glass-ceramics and resin composites. Despite its effectiveness, the harmful and hazardous nature of HF has raised significant safety concerns. In contrast, ammonium fluoride (AF) is known for its relatively low toxicity but has limited etching capability. This study explored the potential of ammonium hydrogen sulfate (AHS), a low-toxicity and weak acid, to enhance the etching ability of aqueous AF solutions for the bonding pretreatment of CAD-CAM materials. This study investigated five types of aesthetic CAD-CAM materials: lithium disilicate glass, feldspathic porcelain, polymer-infiltrated ceramic networks, resin composites, and zirconia. Seven experimental etchants were prepared by varying the amount of AHS added to aqueous AF solutions, with each etchant used to etch the surfaces of the respective CAD-CAM materials. The treated surfaces were analyzed using scanning electron microscopy and confocal laser scanning microscopy. Additionally, the shear bond strength (SBS) of the CAD-CAM materials treated with a luting agent (resin cement) was evaluated. The results indicated that the AF1/AHS3 (weight ratio AF:AHS = 1:3) etchant had the most substantial etching effect on the surfaces of silica-containing materials (lithium disilicate glass, feldspathic porcelain, polymer-infiltrated ceramic networks, and resin composites) but not on zirconia. The SBS of the materials treated with the AF1/AHS3 etchant was comparable to that of the commercial HF etchant. Hence, an AF/AHS mixed solution could effectively etch silica-containing CAD-CAM materials, thereby enhancing their bonding capabilities.

Impact of CAD/CAM Material Thickness and Translucency on the Polymerization of Dual-Cure Resin Cement in Endocrowns.

The objective of this study is to evaluate the impact of the thickness and translucency of various computer-aided design/computer-aided manufacturing (CAD/CAM) materials on the polymerization of dual-cure resin cement in endocrown restorations. Three commercially available CAD/CAM materials-lithium disilicate glass (e.max CAD), resin composite (CERASMART), and a polymer-infiltrated ceramic network (ENAMIC)-were cut into plates with five different thicknesses (1.5, 3.5, 5.5, 7.5, and 9.5 mm) in both high-translucency (HT) and low-translucency (LT) grades. Panavia V5, a commercial dual-cure resin cement, was polymerized through each plate by light irradiation. Post-polymerization treatment was performed by aging at 37 °C for 24 h under light-shielding conditions. The degree of conversion and Vickers hardness measurements were used to characterize the polymerization of the cement. The findings revealed a significant decrease in both the degree of conversion and Vickers hardness with increasing thickness across all CAD/CAM materials. Notably, while the differences in the degree of conversion and Vickers hardness between the HT and LT grades of each material were significant immediately after photoirradiation, these differences became smaller after post-polymerization treatment. Significant differences were observed between samples with a 1.5 mm thickness (conventional crowns) and those with a 5.5 mm or greater thickness (endocrowns), even after post-polymerization treatment. These results suggest that dual-cure resin cement in endocrown restorations undergoes insufficient polymerization.

Effect of Hydrothermal Aging on the Flexural Strength and Microhardness of Materials Used for Additive or Subtractive Manufacturing of Definitive Restorations.

To evaluate the flexural strength (FS) and microhardness of various CAD/CAM restorative materials intended for definitive use. The effect of hydrothermal aging on the mechanical properties of these materials was also investigated. A total of 210 bar-shaped specimens (17 × 4 × 1.5 mm ± 0.02 mm) were fabricated via either subtractive manufacturing (SM) methods-reinforced composite resin (SM-CR), polymer-infiltrated ceramic network (SM-PICN), fine-structured feldspathic ceramic (SMFC), nanographene-reinforced polymethyl methacrylate (PMMA; SM-GPMMA), PMMAbased resin (SM-PMMA)-or additive manufacturing (AM) methods with urethane acrylate-based resins (AM-UA1 and AM-UA2). Specimens were then divided into two subgroups (nonaged or hydrothermal aging; n = 15). A three-point flexural strength test was performed, and five specimens from the nonaged group were submitted to microhardness testing. Specimens were subjected to 10,000 thermal cycles, and the measurements were repeated. Regardless of aging, SM-CR had the highest FS (P < .001), followed by SM-GPMMA (P ≤ .042). In nonaged groups, AM-UA2 had a lower FS than all other materials except SM-FC (P = 1.000). In hydrothermal aging groups, AM specimens had lower FS values than other materials, except SM-PMMA. With regard to microhardness, there was no significant difference found between any of the tested materials (P ≥ .945) in the nonaged and hydrothermal aging groups. The effect of hydrothermal aging on FS varied depending on the type of restorative material. Regardless of aging condition, SM-CR showed the highest FS values, whereas SM-FC had the highest microhardness. Hydrothermal aging had no significant influence on the microhardness of the tested materials.

The Effect of Different Ferrule Configurations and Preparation Designs on the Fatigue Performance of Endodontically Treated Maxillary Central Incisors: A 3D Finite Element Analysis

The presence of an adequate circumferential ferrule is of great importance for the prosthetic rehabilitation of endodontically treated teeth. However, there may not be an adequate circumferential ferrule effect. This study aimed to evaluate the fatigue performance of endocrown and post–core restorations applied to different configurations without an adequate ferrule effect using the finite element method and endeavors to offer a comprehensive perspective on the challenging rehabilitation of maxillary incisors with excessive coronal substance loss, addressing a notable gap in research and providing valuable insights for clinicians. The goal is to address this gap in research and contribute valuable insights that could be beneficial for practitioners. The maxillary central incisor was selected, and lithium disilicate (LS) and a polymer-infiltrated ceramic network (PICN) were used in post–core groups with no ferrule effect (PC0); a 2 mm ferrule effect on the buccal wall (PC1); a 2 mm ferrule effect on the buccal-mesial wall (PC2); a 2 mm ferrule effect on the buccal–mesial–palatal wall (PC3); and a 2 mm circumferential ferrule effect (PC4) In the endocrown groups, an external retention group with a circumferential ferrule (ECER) and an inner retention form group (ECIR) were prepared. Fatigue performance was examined by applying a 150 N oblique load. The evaluation of the fatigue performance of the restorative materials shows that LS always had more successful fatigue performance results, while the post–core groups were generally more successful in terms of dentin survival. In situations where there is insufficient circumferential ferrule, the application of endocrowns is likely to result in a less successful prognosis for survival.

In-vitro evaluation of wear characteristics, microhardness and color stability of dental restorative CAD/CAM materials.

The aim of this study was to demonstrate the vertical and volumetric wear characteristics of CAD/CAM materials. The microhardness and color stability were evaluated. A polymer infiltrated ceramic network CAD/CAM block, resin nanoceramic CAD/CAM blocks, a resin composite, and enamel tissue were investigated. Samples were loaded in a chewing simulator. Other samples were aged and immersed in coffee. Color change was evaluated using the digital image analysis and a spectrophotometer. The data were analyzed using Kolmogorov-Smirnov, Kruskal Wallis, Mann Whitney U, Friedman, Spearman's rho tests (p<0.05). The lowest level of wear was obtained in enamel tissue group 0.20 (Q1:0.14; Q3:0.27μm). Resin composite group 2.48 (Q1:2.12; Q3:2.92) showed lower level of discoloration. No agreement was obtained between the digital image analysis and spectrophotometer data (Spearman's rho -0.314, p=0.014). Similar wear rate to the natural enamel tissue was obtained for Vita Enamic. Digital image analysis was considered a promising technique for monitoring the color change.

Influence of sterilization on the retention forces of lithium disilicate and polymer-infiltrated ceramic-network crowns bonded to titanium base abutments: An in-vitro study.

The aim of this study was to evaluate the effect of sterilization on the retention forces of lithium disilicate (LD) and polymer-infiltrated ceramic network (PICN) crowns bonded to titanium base (Ti-base) abutments. Forty LD and 40 PICN crowns were milled and then bonded to 80 Ti-bases with two resin composite cements: Multilink Hybrid Abutment (mh) and Panavia V5 (pv) for a total of 8 groups (n = 10). Half of the specimens (test) underwent an autoclaving protocol (pressure 1.1 bar, 121°C, 20.5 min) and the other half not (control). Restorations were screw-retained to implants, and retention forces (N) were measured with a pull-off testing machine. The surfaces of the Ti-bases and the crowns were inspected for the analysis of the integrity of the marginal bonding interface and failure mode. Student's t-test, chi-square test, and univariate linear regression model were performed to analyze the data (α = 0.05). The mean pull-off retention forces ranged from 487.7 ± 73.4 N to 742.2 ± 150.3 N. Sterilized groups showed statistically significant overall higher maximum retention forces (p < .05), except for one combination (LD + mh). Sterilization led to an increased presence of marginal gaps and deformities compared to no-sterilization (p < .001), while no statistically significant relationship was found between failure mode and sterilization (p > .05). Sterilization may have a beneficial effect on the retention forces of LD and PICN crowns bonded to titanium base abutments, although it may negatively influence the integrity of the marginal bonding interface.

Fracture Resistance, Failure Mode and Pull-Out Bond Strength of Polymer-Infiltrated Ceramic-Network Post-Core Fabricated using Computer-Aided Design/Computer-Aided Manufacturing

This study compared fracture resistance (FR), failure mode (FM), and pull-out retention in endodontically-treated teeth restored with computer-aided design-and-manufacturing polymer-infiltrated ceramic networks (PICN) to cast post-core. A total of 45 maxillary central incisors were selected, endodontically treated, and were prepared to receive the post-core restorations. The specimens were randomly divided into five groups (n = 9): CG: control (without post-core); NC1, NC2: cast nickel-chromium (Ni-Cr) post-core; and VE1, VE2: PICN post-core. Groups CG, NC1, and VE1 were subjected to the FR test, while Groups NC2 and VE2 were subjected to the pull-out retention test. FR were recorded, and FM were classified as favourable or non-favourable, while the degree of retention in the maximum force was recorded in Newton. A one-way ANOVA was used to assess the FR, and an independent T-test was used for retention of post-core. No significant mean differences of FR between Ni-Cr versus PICN group (p = 0.261). Non-favourable FM was recorded in all samples in the NC group, with 88.9% of the VE group showed favourable FM. No significant mean differences were recorded in retention between NC2 and VE2 (p&gt;0.05). PICN post-core exhibited favourable FR, FM, and retention values, thus having the potential to be used as a substitute post-core in endodontically-treated anterior teeth.

Adhesive Performance of Resin Cement to Glass-Ceramic and Polymer-Based Ceramic CAD/CAM Materials after Applying Self-Etching Ceramic Primer or Different Surface Treatments.

Ensuring optimum bond strength during cementation is vital for restoration success, with the practicality of the process being crucial in clinical practice. This study analyzed the effect of a single-step self-etching ceramic primer (MEP) and various surface treatments on the microshear bond strength (µSBS) between resin cement and glass-ceramic or polymer-based ceramic CAD/CAM materials. Specimens were fabricated from leucite-based glass-ceramic (LEU), lithium disilicate glass-ceramic (LDC), resin nanoceramic (RNC), and polymer infiltrated ceramic network (PICN) (n = 160). They were then classified based on the surface treatments (n = 10): control (no treatment); sandblasting with Al2O3 (AL); etching with hydrofluoric acid (HF); and MEP application. Scanning electron microscopy was used to evaluate the surface topography. µSBS was measured after cementation and thermocycling procedures. Failure modes were examined with a stereomicroscope. Statistical analysis involved two-way analysis of variance and Tukey HSD tests with a significance level of 0.05. µSBS was significantly influenced by both surface treatment and CAD/CAM material type. The most enhanced µSBS values for each material, regarding the surface treatment, were: LEU and LDC, HF; RNC, AL; PICN, AL or HF. MEP significantly increased the µSBS values of CAD/CAM materials except RNC, yet it did not yield the highest µSBS values for any of them.

Development of zirconia-based polymer-infiltrated ceramic network for dental restorative material

Polymer-infiltrated ceramic network (PICN) materials have gained considerable attention as tooth restorative materials owing to their mechanical compatibility with human teeth. However, the mechanical strength of contemporary PICN materials is lower than those of conventional resin composites and ceramics. This study aims to develop novel high-strength PICN for use as a dental restorative material. Zirconia-based PICN (EXP) was fabricated using 3 mol% yttria tetragonal polycrystalline zirconia powder and resin monomers via slip casting, followed by sintering and polymer infiltration. Comprehensive analyses of the microstructure, mechanical properties, and physicochemical properties of EXP were performed using scanning electron microscopy with energy-dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, inorganic content measurements, three-point bending test, Vickers hardness test, two-body wear test, shear bond strength (SBS) test, surface free energy analysis, and water sorption/solubility test. Commercially available computer-aided design/computer-aided manufacturing (CAD/CAM) materials, including resin composite (CERASMART), silicate-based PICN (ENAMIC), and zirconia ceramic (e.max ZirCAD), were used for comparison. The analyses highlight the dual network structure of EXP, which comprised a zirconia skeleton and an infiltrated resin phase. EXP exhibits a flexural strength of 346.0 ± 46.0 MPa, flexural modulus of 44.0 ± 3.7 GPa, and Vickers hardness of 440.1 ± 51.2 VHN. The mechanical properties of EXP are significantly higher than those of CERASMART and ENAMIC but lower than those of ZirCAD. Notably, the EXP hardness closely mimics that of the human enamel. The wear volume, SBS, and water sorption/solubility of EXP are comparable to those of CERASMART and ENAMIC. Therefore, EXP has potential applications as a tooth restorative material.

The influence of titanium-base abutment geometry and height on mechanical stability of implant-supported single crowns.

This study aimed to investigate the influence of titanium base (ti-base) abutment macro- and micro-geometry on the mechanical stability of polymer-infiltrated ceramic network (PICN) screw-retained implant-supported single crowns (iSCs). Twelve specimens per group were used, comprising six different implant/ti-base abutment combinations restored with PICN iSCs: Nb-T (gingival height [GH]: 1.5 mm, prosthetic height [PH]: 4.3 mm), CC (GH: 0.8 mm, PH: 4.3 mm), CC-P (GH: 0.8 mm, PH: 7 mm), Nb-V (GH: 1.5 mm, PH: 6 mm), St (GH: 1.5 mm, PH: 5.5 mm), and Th (GH: 0.5 mm, PH: 9 mm). The specimens underwent thermo-mechanical aging, and those that survived were subsequently subjected to static loading until failure. The data were analyzed using a one-way ANOVA test followed by Tukey post hoc test (α = .05). All specimens survived thermo-mechanical aging without complications, namely, visible cracks, debonding, or screw loosening. Th group demonstrated the highest strength values among all the groups, with significant differences compared to Nb-T (p < .05), CC (p < .001), and St (p < .001). Additionally, CC-P group exhibited significantly superior fracture strength results compared to CC (p < .05) and St (p < .05). The choice of ti-base, particularly prosthetic height, had a significant influence on fracture resistance of PICN iSCs. Nevertheless, the height or geometrical features of the ti-base did not exhibit a significant influence on the mechanical behavior of the iSC/ti-base assembly under thermomechanical loading, as all specimens withstood the aging without complication or failure.

Bond strength to dentin of a Polymer-infiltrate ceramic-network material cemented with dual resin cements submitted to different adhesive strategies

The purpose of the present in vitro study is to assess the immediate and long-term bond strength of a self-adhesive and conventional resin luting agents with a new hybrid restorative material to dentin. Blocks of a polymer-infiltrated ceramic-network (PICN) material (VITA Enamic) were cemented to a flat exposed dentin surface through different protocols. The groups were divided considering the combination of resin luting agent and ceramic surface treatment (U200 – Relyx U200 with silane; Ult + Sil – Relyx Ultimate with silane; Ult + SBU – Relyx Ultimate with Scotchbond Universal) and dentin treatment (NT – no dentin treatment; ER – etch-and-rinse with 35 % phosphoric acid) (n = 6). Beam-shaped specimens were obtained by cutting the cemented restorations. Specimens were submitted to microtensile bond strength in a universal testing machine (EMIC). Half of the specimens were tested 24 h after cementation, and the other half were tested after 12 months of water storage. ANOVA revealed one significant interaction between “time” and “dentin treatment” factors, as ER strategy was associated with bond strength decreases after 12 months. All resin luting agents (u200, Ult + Sil, and Ult + SBU) presented higher immediate μTBS with ER adhesive strategy. As the groups Ult + Sil, with both ER and SE adhesive strategies, and (Ult + SBU), with ER adhesive strategy, showed higher μTBS values after 12 months. It was concluded that conventional dual resin cement, combined with ER strategy produced better bond strength to dentin when cementing indirect PICN restoration.

Influence of Ceramic Materials and Preparation Designs on the Marginal Adaptation of Inlays and Onlays after Thermocycling.

The aim of the current study is to evaluate inlay and onlay marginal adaptation of two different ceramic materials using two intra-coronal preparation designs. An examination of the marginal adaption of two materials, lithium disilicate (IPS e.max CAD) (EX) and polymer infiltrated ceramic network material (PICN; Vita Enamic) (EN), and two preparation designs where D1 represents MOD inlay preparation with no cusp reduction and D2 in addition of the basic MOD preparation, the buccal cusps (functional cusps) were reduced by 1.5 mm. 4 sub-groups (EX-D1), (EX-D2), (EN-D1), (EN-D2) were conducted. Forty (n=40) mandibular molars were used. A stereomicroscope was used to assess the marginal gap before, after cementation and after thermocycling. Values were calculated for the mean, median, standard deviation (Sd), minimum, maximum, and 95% confidence interval. Pair-wise comparisons using Tukey's Post-Hoc test were performed following a significant analysis of variance (ANOVA) P ≤ 0.05. The results revealed that lithium disilicate (IPS e.max CAD) showed statistically significantly higher mean gap distance than polymer infiltrated ceramic network material (PICN; Vita Enamic) (61μm to 99μm). Pair-wise comparisons showed that D2 design has statistically significant higher mean gap values than D1. Both lithium disilicate (IPS e.max CAD) or polymer infiltrated ceramic network material (PICN; Vita Enamic) provided marginal adaptation within clinical accepted range. Polymer infiltrated ceramic network material restorations provided better fit than lithium disilicate restorations. Cusp coverage has a greater marginal gap compared to conventional Preparation.

Comparative Bonding Analysis of Computer-Aided Design/Computer-Aided Manufacturing Dental Resin Composites with Various Resin Cements

The use of dental resin composites adapted to computer-aided design/computer-aided manufacturing (CAD/CAM) processes for indirect tooth restoration has increased. A key factor for a successful tooth restoration is the bond between the CAD/CAM composite crown and abutment tooth, achieved using resin-based cement. However, the optimal pairing of the resin cement and CAD/CAM composites remains unclear. This study aimed to identify the optimal combination of a CAD/CAM composite and resin cement for bonding. A commercial methyl methacrylate (MMA)-based resin cement (Super-Bond (SB)) and four other composite-based resin cements (PANAVIA V5; PV, Multilink Automix (MA), ResiCem EX (RC), and RelyX Universal Resin Cement (RX)) were tested experimentally. For the CAD/CAM composites, a commercial polymer-infiltrated ceramic network (PICN)-based composite (VITA ENAMIC (VE)) and two dispersed filler (DF)-based composites (SHOFU BLOCK HC (SH) and CERASMART300 (CE)) were used. Each composite block underwent cutting, polishing, and alumina sandblasting. This was followed by characterization using scanning electron microscopy, inorganic content measurement, surface free energy (SFE) analysis, and shear bond strength (SBS) testing. The results demonstrated that the inorganic content and total SFE of the VE composite were the highest among the examined composites. Furthermore, it bonded highly effectively to all the resin cements. This indicated that PICN-based composites exhibit unique bonding features with resin cements. Additionally, the SBS test results indicated that MMA-based resin cement bonds effectively with both DF- and PICN-based composites. The combination of the PICN-based composite and MMA-based resin cement showed the best bonding performance.