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Purpose: To compare the translucency parameters and masking abilities of different monolithic CAD/CAM ceramics placed on different-colored substructures. Materials and Methods: Square-shaped specimens (12 × 12 × 1.5 mm) were prepared from feldspathic (C), leucite (EMP), lithium disilicate (e.max), zirconiareinforced lithium silicate (VS), resin nanoceramic (LU), polymer-infiltrated ceramic (VE), hybrid nanoceramic (GC), monolithic zirconia (TZI), and composite resin (TC) blocks (n = 10 per material). After mechanical polishing, the translucency parameter (TP) was calculated. Then, each ceramic specimen was measured on eight substructures, and the color difference between ND2 and each substrate was calculated with the CIEDE2000 formula. TP values were analyzed with one-way ANOVA and Games-Howell tests, and the color differences indicating masking ability were analyzed with two-way ANOVA and Tukey HSD tests. Results: The highest TP was observed in TC, followed by LU, EMP, C,GC, e.max, VS, VE, and TZI. The E00 color difference values of TZI, VS, and VE on all abutment colors, except for ND9, were below the acceptable threshold value. Conclusions: All monolithic ceramic materials used in the study masked the ND1 and ND3 substrates. The ND9, representing severely discolored or devitalized preparations, could not be masked by any monolithic CAD/CAM ceramics used in the study. [ABSTRACT FROM AUTHOR]

Purpose: To compare the masking ability of monolithic CAD/CAM veneers placed over different resin cement shades and substrate colors. Materials and Methods: Veneers were milled from four different monolithic CAD/CAM restorative materials: feldspathic ceramic (VMII), lithium disilicate ceramic (Emax CAD), zirconiareinforced lithium silicate ceramic (VS), and high-translucency zirconia ceramic (YZ-XT). Veneers were luted on natural tooth-colored (ND1) or discolored substrates (ND3 or ND5) using two different resin cement shades (opaque white or translucent). Each CAD/CAM material, resin cement shade, and substrate combination comprised 9 sample veneers (N = 216). Color parameters were obtained using a dental spectrophotometer before and after luting. Color differences (E00) were calculated using CIEDE2000 formula and compared to perceptibility (P = .81 E00 units) and acceptability (AT = 1.77 E00 units) visual thresholds. Color variation data were statistically analyzed using Kruskal-Wallis and Mann-Whitney U tests with Bonferroni-Holm correction (a = .05). Results: The highest E00 value was obtained in the VMII group placed over a discolored substrate, followed by the Emax CAD, YZ-XT, and VS groups. The effect of material types on E00 values was significantly observed when the veneers were luted on discolored substrates using translucent resin cement (P < .05). Conclusions: Restorative material type, substrate color, and resin cement shade affect the masking ability of monolithic CAD/CAM laminate veneers. [ABSTRACT FROM AUTHOR]

Two clinical cases involving the fracture of a natural tooth and one of a ceramic crown are presented and discussed based on fractography principles. In the first case, a patient reported intense pain in a sound third molar where a longitudinal fracture was identified, and the tooth was extracted. In the second case, a posterior rehabilitation using a lithium silicate ceramic crown was carried out, and the patient returned after 1 year with a fractured piece of the crown. Both were analyzed under microscopy to identify the origins of fractures and their causes. The fractures were critically analyzed so that relevant information could be generated from the laboratory to the clinic. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the fracture-behavior of monolithic crowns made of lithium disilicate (IPS e.max CAD, Ivoclar Vivadent; IniBal LiSi Block, GC Dental) and zirconia-reinforced lithium silicate (Celtra Duo, DeguDent; VITA Zahnfabrik) materials before and aKer cyclic faBgue aging. Materials and Methods: Four groups (n = 22/group) of CAD/CAM fabricated upper incisor crowns were produced. All crowns were luted on metal dies with an adhesive dualcure resin cement (G-CEM LinkForce, GC Dental). Half of the crowns in each group (n = 11) were staBcally loaded unBl fracture, without aging. The remaining crowns were subjected to cyclic faBgue aging for 120,000 cycles (Fmax = 220 N) and then loaded staBcally unBl fracture. The fractured models were then visually examined. Scanning electron microsopy (SEM) and energy-dispersive spectroscopy (EDS) were used to evaluate the microstructure of CAD/CAM ceramic materials. The data were staBsBcally analyzed with two-way ANOVA followed by the Tukey HSD test (a = .05). Results: Before cyclic aging, there was no staBsBcally significant difference in load-bearing capacity among the four groups (P = .371). AKer cyclic aging, load-bearing capacity significantly decreased for all groups (P = .000). While the e.max CAD blocks had significantly higher load-bearing capacity (1061 ± 94 N) than both monolithic ceramic crowns (load-bearing capaciBes of the groups) (P < .05), no significant difference was obtained with the IniBal LiSi Block group (920 ± 140 N) (P = .061). Conclusions: The mechanical performance of monolithic ceramic crowns fabricated from lithium disilicate was befer than zirconia-reinforced lithium silicate aKer cyclic faBgue aging. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effects of two different lasers and their use in combination with hydrofluoric acid (HF) etching on the surface roughness of zirconia-reinforced lithium silicate (ZLS) ceramics and their shear bond strength (SBS) to composite resin. Materials and Methods: The five study groups were as follows: (1) Group H = HF etching; (2) Group N = Nd:YAG (neodymium: yttrium-aluminum-garnet) laser; (3) Group NH = Nd:YAG laser + HF gel; (4) Group E = Er:YAG (erbium: yttrium-aluminum-garnet) laser; and (5) Group EH = Er:YAG laser + HF gel. Surface roughness was assessed using a noncontact profilometer, and SBS tests were conducted with a universal testing machine. Results: The mean SBS values were 16.23 ± 1.77 MPa for Group H, 17.1 ± 1.65 MPa for Group N, 16.65 ± 1.11 MPa for Group NH, 8.08 ± 1.12 MPa for Group E, and 11.58 ± 0.82 MPa for Group EH. There were significant differences between groups E and EH (P < .001) but no significant differences (P > .05) among the other groups. Conclusions: Clinicians may prefer Nd:YAG laser or the combination of Nd:YAG and HF to intraorally repair fractured areas. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the performance of fully crystallized zirconia-reinforced lithium silicate (Celtra Duo, ZLS-CD), partially crystallized zirconia-reinforced lithium silicate (Vita Suprinity, ZLS-VS), and partially sintered lithium disilicate-based (IPS e.max CAD, LD) glass-ceramics submitted to polishing, glazing, or no surface treatment after aging. Material and Methods: Samples of each glass-ceramic material were subjected to polishing with rubber cups (POL), glazing (GL), or no treatment (control: unpolished) and afterward aged with 18,000 thermal cycles (5°C to 55°C). The average roughness, 2D and 3D morphology, contact angle, multispecies biofilm formation (Streptococcus mutans and Candida albicans), and mechanical strength were evaluated with atomic force microscopy (AFM, n = 5), sessile-drop goniometry (n = 5), spectrophotometry (n = 5), and the flexural strength test (n = 10), respectively. Data were analyzed using two-way ANOVA and Tukey test (a = 5%). Results: POL produced lower surface roughness than GL, and ZLS-CD presented higher roughness than LD (P < .05). Surfaces without polishing displayed higher roughness than the POL group (P < .001), greater contact angle (P < .001), and significant morphologic changes, regardless of the glassceramic material. Irrespective of the treatment, the contact angle was higher in the ZLS-CD group, and regardless of the material, there was higher biofilm formation and lower flexural strength of the unpolished compared to the POL or GL ceramics. Conclusions: POL promoted lower roughness and minor morphologic surface alterations, but biofilm formation and flexural strength were similar to the GL group. In general, ZLSCD and ZLS-VS showed more similar behavior than LD, which makes ZLS glass-ceramic a good option for indirect restorations. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of cavity tapering on marginal and internal adaptation of endocrowns fabricated from two different ceramic materials. Materials and Methods: Two mandibular molar model teeth were prepared with two different cavity tapers (5 and 10 degrees). A total of 40 endocrowns (four groups of 10 each) were milled using lithium disilicate and zirconia-reinforced lithium silicate ceramics for each cavity taper. The marginal and internal adaptation of endocrowns were measured by a stereomicroscope (×30) at 18 different points. The data were statistically analyzed using independent t test (P < .05). Results: A statistically significant difference was shown among the tested groups at 10 degrees of taper (P < .001). At 5 degrees of taper, the difference was insignificant. The greatest internal gap was observed at the pulpal floor in all tested groups. Conclusion: All materials had clinically acceptable internal and marginal gaps; however, lithium disilicate ceramic had significantly better adaptation at 10 degrees of taper. [ABSTRACT FROM AUTHOR]

Minimally invasive prosthetic procedures (MIPPs) have been suggested and utilized for the esthetic rehabilitation of severely worn dentition. Minimizing the reduction of tooth structure and the use of additional adhesive techniques are key elements to ensure long-term results. This article presents the long-term result of this restorative technique. A total of 1,040 lithium disilicate restorations were adhesively luted, and 45 patients and 87 arches were treated. The cumulative survival rate recorded was 99.15%, with a 10-year survival probability of 96.5%. These remarkable results strongly support the use of MIPP as a restorative option for severely worn dentition. [ABSTRACT FROM AUTHOR]

Purpose: To test whether internal accuracy affects the load-bearing capacity of 0.5-mm-thick occlusal veneers made out of milled or heat-pressed lithium disilicate (LS2).Materials and Methods: Extracted human molars (N = 80) were divided into four groups (n = 20 each) depending on the bonding substrate (enamel [E] or dentin [D]) and the fabrication method (milling [CAD] or heat pressing [PRE]) for the occlusal LS2 veneers: (1) E-CAD, (2) D-CAD, (3) E-PRE, or (4) D-PRE. After restoration fabrication, the abutment teeth and the corresponding restorations were scanned and superimposed in order to measure the marginal and internal accuracy. After adhesive cementation, the specimens were thermomechanically aged and thereafter loaded until fracture. The load-bearing capacities (Fmax) were measured. Fmax and the marginal and internal accuracy between the groups were compared using Kruskal-Wallis test (P < .05) and pairwise group comparisons. In addition, the relationship between Fmax and the internal accuracy was analyzed using Spearman rank correlation.Results: Median Fmax values (and first and third quartiles) per group were as follows: 1,495 N (Q1: 932; Q3: 2'318) for E-CAD; 1,575 N (Q1: 1,314; Q3: 1,668) for E-PRE; 1,856 N (Q1: 1,555; Q3: 2,013) for D-CAD; and 1,877 N (Q1: 1,566; Q3: 2,131) for D-PRE. No statistical difference was found between the groups (P = .0981). Overall, the internal accuracy in the areas of the cusp (P < .0007) and fossa (P < .0001) showed significant differences. While no significant differences were detected in the marginal area (P = .3518), a significant correlation with a negative linear relationship was found between the 3D internal accuracy and the Fmax values (P = .0007).Conclusion: An increase in the internal accuracy raised the load-bearing capacity of minimally invasive LS2 occlusal veneers. In general, the restorations bonded to dentin in the occlusal regions showed a better accuracy compared to those bonded to enamel. [ABSTRACT FROM AUTHOR]

This clinical report presents the use of a modified polyetheretherketone (PEEK) post and core in order to support a lithium disilicate ceramic crown for a maxillary lateral incisor. When considering post-and-core restorations, material flexibility is essential to prevent root fractures. The low elastic modulus of PEEK (4 GPa) could result in lower root fracture rates, preserving tooth structure and favoring tooth re-restoration if the post fractures. PEEK is biocompatible, presents adequate bond strength with dentin when bonded with a resin cement, and can be used under ceramic restorations because of its white, esthetic color. PEEK posts and cores could also cost less when fabricated using common laboratory procedures. Polyetheretherketone (PEEK) posts and cores could be a viable alternative to rigid cast or zirconia posts, or even to fiber-reinforced composite posts, especially when combined with lithium disilicate crowns. [ABSTRACT FROM AUTHOR]

Purpose: To compare the marginal and internal gap values of different types of ceramic crowns fabricated based on digital and conventional impression methods. Materials and Methods: Ten noncarious extracted human teeth were prepared, and 60 restorations were made using six different impression and fabrication methods. Silicone replicas were obtained for marginal and internal gap evaluation. Statistical analyses were performed using Mann-Whitney U and Kruskal-Wallis tests (P < .05). Results: Statistically significant differences were found among various impression and fabrication methods. The smallest gap value was shown by the monolithic zirconia indirect digital scanning group (31.13 µm), and the largest for the lithium disilicate indirect digital scanning group (90.09 µm). Conclusion: The marginal and internal gap values of the restorations in the present study were 31.13 to 90.09 µm. The marginal and internal discrepancies of the tested materials were considered clinically acceptable. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the 2-year performance of definitive implant- or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate placed to restore premolars and molars in clinical cases of partial edentulism. Materials and Methods: All patients received a three-unit fixed restoration made of monolithic, hot-pressed, zirconia-reinforced lithium silicate glass-ceramic. The restoration was cemented to two natural teeth or attached to two 3.5- or 4.5-mm-diameter square threaded, gritblasted, acid-etched integrated implants with a Morse taper connection. Peri-implant pocket depth and bone and soft tissue remodeling were recorded for 2 years at each follow-up visit. Esthetic, functional, and biologic United States Public Health Services (USPHS) parameters modified by the World Dental Federation study design were assessed yearly until the final follow-up appointment. At the time of placement of the definitive restorations and at the 2-year follow-up visit, the opposing dentitions were identified by type of restoration and supporting structures. Results: A total of 100 patients were consecutively enrolled in the period between June 2016 and July 2017, and 50 patients each received an implant-supported restoration (Group A) or a tooth-supported restoration (Group B). One (2%) of the 50 implant-supported prostheses fractured after 21 months of function. None of the other prostheses failed or became loose or detached. No significant differences involving probing levels or bone and soft tissue remodeling were found between the follow-up times. No cases of inflammation or infection of the mucosal cuff around the neck of the implants were recorded. The most common issue occurred immediately after placement of the prosthesis, when 3 patients (6%) from Group A and 4 patients (8%) from Group B asked for a modification of tooth shade. Conclusion: Implant-supported or tooth-supported three-unit fixed dental prostheses made of zirconia-reinforced lithium silicate can be used to successfully restore cases of posterior partial edentulism. The 2-year results of this report will be studied more in depth in ongoing long-term research. [ABSTRACT FROM AUTHOR]

Purpose: To compare the load-bearing capacity after long-term use (5-year simulation) of posterior three-unit implant-supported fixed partial dentures (FPDs) fabricated with different esthetic materials.Materials and Methods: A total of 20 specimens fabricated from one design file using CAD/CAM were divided into four groups: polyetherketoneketone (PEKK) veneered with composite resin (CR); PEKK veneered with lithium disilicate (LD); zirconia veneered with fluorapatite (FA); and monolithic zirconia. Samples were placed into a chewing simulator with simultaneous thermocycling. The fracture load after aging was measured using the universal testing machine with load on the central fossa of the pontic.Results: FPDs fabricated with PEKK + LD had significantly higher fracture load (1,526.56 [SD 95.54] N) compared to PEKK + CR (1,069.54 [SD 67.94] N) (P < .05). FPDs fabricated with zirconia materials had significantly higher fracture load compared to PEKK materials (P < .05). There was no significant difference between monolithic zirconia and zirconia + FA (P > .05).Conclusion: FPDs fabricated with PEKK + LD were superior to PEKK + CR. These materials can be promising alternatives for use as implant-supported FPD materials in the high-stress-bearing posterior region. Zirconia + FA can be an alternative to monolithic zirconia in cases that require more esthetics. [ABSTRACT FROM AUTHOR]

Purpose: To compare the marginal vertical misfit between implant-supported frameworks fabricated using CAD/CAM systems and the conventional technique (lost-wax casting).Materials and Methods: This review was performed according to PRISMA criteria and registered on PROSPERO (CRD42017055685). An electronic search was performed independently by two examiners in the MEDLINE (Pubmed), Embase, Web of Science, and Cochrane Library databases to find studies published up to April 2018.Results: The database search yielded 507 references. After removing duplicate references, 384 studies remained. Eleven in vitro studies were selected according to the eligibility criteria (inter-reader κ = 0.88). Nine different CAD/CAM systems were used to fabricate 172 frameworks of different materials, including zirconia, monolithic lithium disilicate, and metallic alloys. Subgroup analyses were performed for different types and retention systems of the frameworks. In the general analysis, marginal misfit observed with the CAD/CAM systems was lower than with the conventional method (P = .003), as was observed in the subgroup analysis for single-unit frameworks (P < .00001). For fixed (P = .89), cemented (P = .60), and screwed (P = .18) frameworks, no significant difference was observed between the evaluated techniques.Conclusion: The CAD/CAM systems showed improved marginal fit over the conventional lost-wax casting technique for fabricating single-unit frameworks; however, in the subgroup analyses, no difference was observed for the fixed implant-supported type or for the retention systems evaluated. [ABSTRACT FROM AUTHOR]

Purpose: To investigate the efficacy of different ceramic surface cleaning methods after saliva contamination on the resin bond strength to lithium disilicate ceramics. Materials and Methods: 300 e.max CAD blocks (Ivoclar Vivadent) were polished with 600-grit silicon carbide paper and divided into five groups with or without human saliva contamination and according to the surface treatment performed (n = 10); control: no pretreatment; MP: Monobond Plus; PA+MP: 37% phosphoric acid (PA) followed by MP; HF+MP: 5% hydrofluoric acid (HF) followed by MP; MEP: Monobond Etch & Prime. The specimens were bonded with one of three resin cements: Variolink Esthetic DC (VE), Multilink Automix (MA) and Speed CEM (SC). After 24-h water storage, tensile bond strength (TBS) was measured. The ceramic surfaces after pretreatment were analyzed using x-ray photoelectron spectroscopy (XPS). Results: XPS analysis showed similar elemental distributions between saliva contamination vs no saliva in PA, HF, and MEP. The TBSs were significantly influenced by surface treatments (p < 0.05). HF+MP and MEP showed statistically non-significantly different bond strengths to saliva-contaminated HF+MP and MEP, but were different from MP and saliva-contaminated MP. The TBSs after 24 h were significantly higher in HF+MP and MEP groups with VE. HF+MP and MEP did not show statistically significant differences among any groups with or without saliva contamination. Conclusion: Surface treatments with PA or HF followed by silane or by MEP alone were effective in removing saliva contamination and enhancing the resin bond strength. [ABSTRACT FROM AUTHOR]

Purpose: To assess the clinical performance of lithium disilicate single restorations on natural teeth.Materials and Methods: All patients who received lithium disilicate single restorations between 2009 and 2013 at the dental clinic of the University of Ferrara were recalled for clinical evaluation. A total of 43 partial and total restorations in 17 patients were evaluated from a minimum of 36 months follow-up to a maximum of 81 months follow-up, with a mean follow-up of 51 months.Results: The cumulative survival rate was 97.7%, and the cumulative success rate was 94.2%.Conclusion: Lithium disilicate can be successfully used for single-tooth restorations. [ABSTRACT FROM AUTHOR]

Purpose: To compare operating time and patient perception of conventional impression (CI) taking and intraoral scanning (IOS) for manufacture of a tooth-supported crown.Materials and Methods: A total of 19 patients needing indirect full-coverage restorations fitting the requirements for a split-mouth design were recruited. Each patient received two lithium disilicate crowns, one manufactured from CI taking and one from IOS. Both teeth were prepared following the manufacturers' recommendations. For both impression techniques, two retraction cords soaked in 15% ferric sulphate were used for tissue management. CIs were taken in a full-arch metallic tray using one-step, two-viscosity technique with polyvinyl siloxane silicone. The operating time for each step of the two impression methods was registered. Patient perception associated with each method was scored using a 100-mm visual analog scale (VAS), with 100 indicating maximum discomfort.Results: Median total operating time for CI taking was 15:47 minutes (interquartile range [IQR] 15:18 to 17:30), and for IOS was 5:05 minutes (IQR 4:35 to 5:23). The median VAS score for patient perception was 73 (IQR 16 to 89) for CI taking and 6 (IQR 2 to 9) for IOS. The differences between the two groups were statistically significant (P < .05) for both parameters.Conclusion: IOS was less time consuming than CI taking, and patient perception was in favor of IOS. [ABSTRACT FROM AUTHOR]

Objective: Several methods for the evaluation of fit of computer-aided design/computer-assisted manufacture (CAD/CAM)- fabricated restorations have been described. In the study, digital models were recorded with an intraoral scanning device and were measured using a new three-dimensional (3D) computer technique to evaluate restoration internal fit. The aim of the study was to evaluate the internal adaptation and fit of chairside CAD/CAM-fabricated zirconia-reinforced lithium silicate ceramic crowns fabricated with different post-milling protocols. The null hypothesis was that different post-milling protocols did not influence the fitting accuracy of zirconia-reinforced lithium silicate restorations. Method and Materials: A master all-ceramic crown preparation was completed on a maxillary right first molar on a typodont. Twenty zirconia-reinforced lithium silicate ceramic crowns (Celtra Duo, Dentsply Sirona) were designed and milled using a chairside CAD/CAM system (CEREC Omnicam, Dentsply Sirona). The 20 crowns were randomly divided into two groups based on post-milling protocols: no manipulation after milling (Group MI) and oven fired-glazing after milling (Group FG). A 3D computer method was used to evaluate the internal adaptation of the crowns. This was based on a subtractive analysis of a digital scan of the crown preparation and a digital scan of the thickness of the cement space over the crown preparation as recorded by a polyvinylsiloxane (PVS) impression material. The preparation scan and PVS scan were matched in 3D and a 3D difference analysis was performed with a software program (OraCheck, Cyfex). Three areas of internal adaptation and fit were selected for analysis: margin (MA), axial wall (AX), and occlusal surface (OC). Statistical analysis was performed using 80% percentile and one-way ANOVA with post-hoc Scheffé test (P = .05). Results: The closest internal adaptation of the crowns was measured at the axial wall with 102.0 ± 11.7 µm for group MI-AX and 106.3 ± 29.3 µm for group FG-AX. The largest internal adaptation of the crowns was measured for the occlusal surface with 258.9 ± 39.2 µm for group MI-OC and 260.6 ± 55.0 µm for group FG-OC. No statistically significant differences were found for the post-milling protocols (P > .05). The 3D difference pattern was visually analyzed for each area with a color-coded scheme. Conclusion: Post-milling processing did not affect the internal adaptation of zirconia-reinforced lithium silicate crowns fabricated with a chairside CAD/CAM technique. The new 3D computer technique for the evaluation of fit of restorations may be highly promising and has the opportunity to be applied to clinical studies. [ABSTRACT FROM AUTHOR]

Purpose: Lithium disilicate (LDS) glass-ceramic restorations are routinely used, but results over a period longer than 10 years are rare. The objective of this study was to obtain long-term clinical data on monolithic LDS posterior crowns provided by a single restorative dentist.Materials and Methods: Eligible patients who received a circumferential LDS crown in the posterior region between 1997 and 2010 were invited to participate in a clinical examination in 2015. This consisted of intraoral inspection and radiographs, performed by one observer and according to standardized criteria. Probability of survival was estimated using Kaplan-Meier survival analysis.Results: A total of 13 patients (n = 87 restorations) fulfilled the inclusion criteria. Of these, 12 patients were available for clinical evaluation (n = 74 restorations). After 5, 10, and 15 years, the cumulative chance of survival of the restoration was 92%, 85.5%, and 81.9%, respectively, with a median observation period of 12.8 years. Of the 74 restorations, 13 failed: 4 because of secondary caries, 2 because of debonding, and 7 because of fracture of the restoration.Conclusion: Lithium disilicate can be regarded as a strong and fracture-load-resistant restorative material providing reliable long-term clinical performance. [ABSTRACT FROM AUTHOR]

Objective: No clinical data are available for the new computer- aided design/computer-assisted manufacture (CAD/CAM) material zirconia-reinforced lithium silicate (ZLS) ceramic. This study describes preliminary clinical results for indirect ZLS CAD/CAM restorations after 12 months. Method and Materials: Indirect restorations were fabricated, using the CEREC method and intraoral scanning (CEREC Omnicam, CEREC MCXL). Sixty-seven restorations were seated adhesively (baseline). Sixty restorations were evaluated after 12 months (follow- up), using modified FDI criteria. Two groups were established, according to ZLS restorations’ post-processing procedure prior to adhesive seating: group I (three-step polishing, n = 32) and group II (fire glazing, n = 28). Statistical analysis was performed with Mann-Whitney U test and Wilcoxon test (P < .05). Results: The success rate of indirect ZLS CAD/ CAM restorations after 12 months was 96.7%. Two restorations clinically failed as a result of bulk fracture (failure rate 3.3%). No statistically significant differences were found for baseline and follow-up criteria (Wilcoxon test, P > .05). Statistically significant differences were found for criteria surface gloss for group I and group II (Mann-Whitney U test, P < .05). Conclusion: This study demonstrates ZLS CAD/CAM restorations have a high clinical success rate after 12 months. A longer clinical evaluation period is necessary to draw further conclusions. [ABSTRACT FROM AUTHOR]

Purpose: Various materials and systems for bonding lithium disilicate to the tooth substrate are available to clinicians, who can adapt the materials to each clinical situation to maximize the performance of indirect esthetic restorations. This study aimed to evaluate the degree of conversion (DC) and the microhardness (MH) of a dual-curing and a light-curing cement under lithium disilicate discs of different thicknesses.Materials and Methods: A total of 48 lithium disilicate (IPS e.max CAD, Ivoclar Vivadent) samples were prepared and divided into three groups (n = 16) according to the thickness (group A was 0.6 mm; group B was 1.0 mm; group C was 1.5 mm). Each group was further divided into two subgroups (n = 8) according to the resin cement employed, NX3 (Kerr) or Choice 2 (Bisco). A standardized quantity of cement was placed on the sample, and DC was evaluated with an attenuated total reflectance Fourier transformed infrared spectrophotometer (Nicolet IS10, Thermo Scientific). Twenty-four hours after DC was established, Vickers test was performed on the cement with a microindentometer (Leica Microsystems). Results were statistically analyzed with analysis of variance test and significance set at P < .05.Results: Statistical analysis showed cement type had a significant influence (P = .005) on DC. MH results were influenced by thicknesses only between 0.6 and 1.5 mm when light-cured cement was employed.Conclusion: The light-curing and the dual-curing cements reached comparable DCs between 0.6 and 1.5 mm. However, the light-curing resin showed a higher DC and MH. [ABSTRACT FROM AUTHOR]

Purpose: To test the effect of surface conditioning protocols on the reparability of CAD/CAM zirconia-reinforced lithium silicate ceramic compared to lithium-disilicate glass ceramic. Materials and Methods: Zirconia-reinforced lithium silicate ceramic (Vita Suprinity) and lithium disilicate glass-ceramic blocks (IPS e.max CAD) were categorized into four groups based on the surface conditioning protocol used. Group C: no treatment (control); group HF: 5% hydrofluoric acid etching for 60 s, silane (Monobond-S) application for 60 s, air drying; group HF-H: 5% HF acid etching for 60 s, application of silane for 60 s, air drying, application of Heliobond, light curing for 20 s; group CO: sandblasting with CoJet sand followed by silanization. Composite resin (Tetric Evo Ceram) was built up into 4 x 6 x 3 mm blocks using teflon molds. All specimens were subjected to thermocycling (5000x, 5°C to 55°C). The microtensile bond strength test was employed at a crosshead speed of 1 mm/min. SEM was employed for evaluation of all the debonded microbars, the failure type was categorized as either adhesive (failure at adhesive layer), cohesive (failure at ceramic or composite resin), or mixed (failure between adhesive layer and substrate). Two-way ANOVA and the Tukey's HSD post-hoc test were applied to test for significant differences in bond strength values in relation to different materials and surface pretreatment (p < 0.05). Results: The highest microtensile repair bond strength for Vita Suprinity was reported in group CO (33.1 ± 2.4 MPa) and the lowest in group HF (27.4 ± 4.4 MPa). Regarding IPS e.max CAD, group CO showed the highest (30.5 ± 4.9 MPa) and HF the lowest microtensile bond strength (22.4 ± 5.7 MPa). Groups HF, HF-H, and CO showed statistically significant differences in terms of all ceramic types used (p < 0.05). The control group showed exclusively adhesive failures, while in HF, HF-H, and CO groups, mixed failures were predominant. Conclusions: Repair bond strength to zirconia-reinforced lithium silicate ceramics and lithium-disilicate glass ceramic could be improved when ceramic surfaces are sandblasted with CoJet sand followed by silanization. [ABSTRACT FROM AUTHOR]

Purpose: To demonstrate the influence of restorative material on the success of clinical bonding to zirconia.Materials and Methods: A total of 50 participants with a single implant received screw-retained restorations; ie, Lava Ultimate (LU) crowns extraorally bonded to zirconia abutments. After 1 year, lithium disilicate (LDS) was used as an alternative restorative material. These restorations were also followed for 1 year.Results: Forty LU restorations (80%) debonded within 1 year of clinical service, whereas no bonding failures occurred with LDS restorations.Conclusion: The choice of restorative material for single crowns luted to zirconia implant abutments strongly influences the incidence of bonding failures. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate in vitro the effect of using titanium tetrafluoride as an alternative etchant prior to the silani-zation of the bonding surface on the long-term resin bond strength to lithium disilicate ceramic. Materials and Methods: Disk-shaped specimens made of lithium disilicate ceramic were ground with abrasive paper, then etched with aqueous solutions (2.5% and 5%) of titanium tetrafluoride for 60 s, 120 s and 240 s. Positive control specimens were etched with 5% hydrofluoric acid for 20 s and negative control specimens were not etched. Afterwards, bonding surfaces of all specimens were silanized. Plexiglas tubes filled with a composite resin were bonded to the specimens using an alignment apparatus and a composite luting resin. After storage in 37°C tap water for three days (n = 8) and after storage in 37°C tap water for 150 days interrupted by 5 x 7500 thermal cycles (n = 8), tensile bond strength (TBS) was measured in a universal testing machine at a crosshead speed of 2 mm/min. Results: After artificial aging, all specimens etched with titanium tetrafluoride debonded spontaneously resulting in a TBS of 0 MPa. Therefore, statistical analysis revealed a highly significant difference between the positive control and the test groups after 150 days storage. Conclusion: Etching the bonding surface of lithium disilicate ceramic restorations with hydrofluoric acid is still a "gold standard" and cannot be replaced by titanium tetrafluoride [ABSTRACT FROM AUTHOR]

Purpose: This study evaluated the microtensile bond strength (uTBS) of 3 different resin cements to lithium-disil-icate ceramic using two assemblies: ceramic-cement-ceramic (CCC) and ceramic-cement-dentin (CCD). Materials and Methods: The bonding surfaces of lithium disilicate ceramic blocks (5x5x4 mm) (Nbiock = 90) were etched with 4% hydrofluoric acid for 20 s and silanized. Flat dentin surfaces of human third molars were conditioned according to the respective manufacturer's specifications for three types of resin cements (ML: Multilink, Ivoclar-Vivadent; PF: Panavia F, Kuraray; SB: Super Bond C&B, Sun Medical). While one set of ceramic blocks (n = 30) was cemented to another equal set (CCC assembly), another set of ceramic blocks (n = 30) was cemented on flat dentin (CCD assembly). The bonded specimens were stored in distilled water at 37°C for 24 h, and then sectioned along the x- and y-axes to obtain nontrimmed beam specimens. The beam specimens were randomly divided into two conditions: dry condition (DC - immediate testing); and aging condition (AC - thermo-cycling 12,000 times + water storage for 150 days). The uTBS bond strength test was performed using a universal testing machine (1 mm/min). After debonding, the substrate and adherent surfaces were analyzed using a scanning electron microscope to categorize the failure types. The data were statistically evaluated using 2-way AN0VA and Tukey's test (5%). Results: While the mean uTBS of CCC assemblies were significantly influenced by the cement type (p < 0.05) and aging (p < 0.05), CCD assemblies showed a significant effect of the cement (p < 0.05) but not the aging (p > 0.05). Without aging (DC), the mean uTBS (MPa) of SB (26.9) and PF (26.9) were significantly higher than ML (18.5) (p < 0.05). For CCC after aging (AC), SB (26.6) showed higher mean μTBS than those of PF (16.4) and ML (18.5) (p < 0.05). However, in CCD after AC, no significant difference was found between the groups (p > 0.05). In both CCC and CCD assemblies, pre-test failures were the least with SB cement. Regardless of the resin cement type employed and storage conditions, adhesive failures ranged between 35.3% and 88.9%, cohesive failures in cement between 2.3% and 35.3%, and cohesive failures in ceramic between 3.3% and 6.8%. Conclusion: SB resin cement demonstrated the highest bond strength to a lithium disilicate ceramic in both tests assemblies with and without aging conditions [ABSTRACT FROM AUTHOR]

Purpose: The aim of this prospective study was to evaluate the clinical efficacy and long-term survival rate of three-unit fixed partial dentures (FPDs) made from lithium disilicate-based core ceramic. Materials and Methods: Twenty-one three-unit FPDs were placed in 19 patients to replace single lost teeth in the esthetic area, following a study protocol that took clinical, esthetic, and radiologic aspects into consideration. Each case was reviewed at 1 week following placement, at 6 months, and then annually for 10 years. Statistical analysis was performed using Kaplan- Meier survival analysis. Results: Out of the 19 patients, 14.3% presented reversible postoperative sensitivity. Recession was observed in 24% of dental posts, and 7.1% presented marginal discoloration. Treatment did not increase either Bleeding or Plaque Index scores at prepared teeth; secondary caries did not appear either. The restorations' survival rate at the 10-year follow-up was 71.4%; six FPDs had fractured and one debonded. Conclusions: Fracture failure rate was 28.6% after 10 years; a high percentage corresponded to connector fractures and occurred during the first 5 years. Lithium disilicate glass-ceramic FPDs present a higher risk of fracture than standard therapies (metal-ceramic) or other more recently developed ceramic materials. The prognosis for survival improves for Class I occlusion and nonparafunctional patients. [ABSTRACT FROM AUTHOR]

The article presents clinical and laboratory steps for an aesthetic and functional protocol for full-mouth rehabilitation that promotes dental team cooperation and patient understanding. It examines a case report of a 64-year-old Caucasian woman suffering from an accentuated overbite and malocclusion and provides treatment planning to correct the maxillary central incisors overbite. It talks about preparation of the teeth for all-ceramic crowns and CAD/CAM systems to fabricate frameworks.

The article presents a case study of the use of minimally invasive prosthetic procedures (MIPP) on a 43-year-old male patient with dentition stained by tetracycline and generalized enamel wear. It provides information on principles of MIPP modality which include monolithic lithium disilicate posterior restorations, adhesive bonding, and reduced tooth preparation. It mentions after a diagnostic wax-up was completed, a mock-up of the proposed restorations was made using flowable composite resin.

The aim of this prospective clinical split-mouth study was to investigate the long-term performance of pressed and computer-aided design/computer-assisted manufacture (CAD/CAM) all-ceramic partial-coverage restorations (PCRs). Twenty-five patients were restored with 40 lithium disilicate pressed PCRs (IPS e.max-Press, Ivoclar Vivadent) and 40 leucite-reinforced glass-ceramic CAD/CAM PCRs (ProCAD, Ivoclar Vivadent). All restorations were placed in vital first or second molars. The 7-year Kaplan-Meier survival rate was 100% for pressed PCRs and 97% for CAD/ CAM PCRs. Both systems showed significant deterioration over time in all modified United States Public Health Service criteria. Increased surface roughness and impaired color match were significantly more prevalent with pressed PCRs. Based on the 7-year data, both all-ceramic systems can be considered reliable treatment options for posterior PCRs. [ABSTRACT FROM AUTHOR]

The article presents a case report of a 17-year-old male patient whose maxillary left central incisor had trauma-induced ankylosis. It states the tooth was stable despite severe root resorption shown in periapical radiographs. It mentions the use of vinyl polysiloxane dental impressions and reports labioversion of the incisor was evident. It talks about the presents of unexposed dental enamel and possible gingival resection and also mentions the installation of a lithium disilicate dental crown.

The article focuses on the concept of visagism in dental composition and presents a case study of a 34-year-old female patient who had a complaint about the worn aspect of her teeth. It states the definition of visagism was developed by artist Philip Hallawell and involves the creation of a customized personal image expressing a person's sense of identity. It mentions the creation of dental veneers fabricated in lithium disilicate glass-ceramics which would accent her sensitivity and femininity.

The article presents a case study of a female patient who wanted to improve the aesthetic appearance of her maxillary anterior teeth while avoiding an orthodontic realignment. It states her central incisors had been endodontically treated years previous and comments on the use of crowns for her central incisors and veneers for her lateral incisors to restore the proper relationship between her teeth. It mentions the use of a metal-free method in fabricating lithium disilicate veneers and crowns.

The article presents a case study of a 25-year-old male patient who had weakening and fracturing of the maxillary incisal edges. It comments that the patient showed generalized initial dental erosion and had an accelerated loss of dental enamel. It mentions that palatal and facial dental veneers were also used to restore incisors which showed darkening, and talks about the use of additive diagnostic wax-up to prepare for lithium disilicate ceramic onlays which were etched with hydrofluoric acid.

The article presents a case study of a 16-year-old male patient who was diagnosed with the autosomal dominant genetic trait dentinogenesis imperfecta (DI) type II. It states that the DI is characterized by hard tissue discoloration of the dentin, resulting from a defect in the dentin sialophosphoprotein gene. It mentions the dentin malformation compromised the connection between dentin and enamel. It comments on the use of a thermoformed template and casts in creating lithium disilicate crowns .

Purpose: The aim of this research was to evaluate the fatigue behavior and reliability of monolithic computer-aided design/computer-assisted manufacture (CAD/CAM) lithium disilicate and hand-layer-veneered zirconia all-ceramic crowns. Materials and Methods: A CAD-based mandibular molar crown preparation, fabricated using rapid prototyping, served as the master die. Fully anatomically shaped monolithic lithium disilicate crowns (IPS e.max CAD, n = 19) and hand-layer-veneered zirconia-based crowns (IPS e.max ZirCAD/Ceram, n = 21) were designed and milled using a CAD/CAM system. Crowns were cemented on aged dentinlike composite dies with resin cement. Crowns were exposed to mouth-motion fatigue by sliding a WC-indenter (r = 3.18 mm) 0.7 mm lingually down the distobuccal cusp using three different stepstress profiles until failure occurred. Failure was designated as a large chip or fracture through the crown. If no failures occurred at high loads (> 900 N), the test method was changed to staircase r ratio fatigue. Stress level probability curves and reliability were calculated. Results: Hand-layer-veneered zirconia crowns revealed veneer chipping and had a reliability of < 0.01 (0.03 to 0.00, two-sided 90% confidence bounds) for a mission of 100,000 cycles and a 200-N load. None of the fully anatomically shaped CAD/CAM-fabricated monolithic lithium disilicate crowns failed during step-stress mouth-motion fatigue (180,000 cycles, 900 N). CAD/CAM lithium disilicate crowns also survived r ratio fatigue (1,000,000 cycles, 100 to 1,000 N). There appears to be a threshold for damage/bulk fracture for the lithium disilicate ceramic in the range of 1,100 to 1,200 N. Conclusion: Based on present fatigue findings, the application of CAD/CAM lithium disilicate ceramic in a monolithic/fully anatomical configuration resulted in fatigue-resistant crowns, whereas hand-layer-veneered zirconia crowns revealed a high susceptibility to mouth-motion cyclic loading with early veneer failures. [ABSTRACT FROM AUTHOR]

Purpose: The aim of this study was to evaluate the fracture resistance of fatigued lithium disilicate pressed zirconia crowns versus other ceramic crowns.Materials and Methods: Lithium disilicate pressed zirconia, fluorapatite pressed zirconia, monolithic lithium disilicate, and monolithic zirconia crowns were fabricated. Cyclic and static loadings were applied to the mesiobuccal cusp tip after thermocycling and fracture strengths were recorded.Results: Fatigued lithium disilicate pressed zirconia crowns were found to have a fracture resistance of 9,117.81 ± 727.04 N, compared with 9,240.61 ± 887.21 N for monolithic zirconia crowns, 3,030.18 ± 1,505.83 N for fluorapatite pressed zirconia crowns, and 4,173.94 ± 877.46 N for monolithic lithium disilicate crowns (P = .001).Conclusion: This in vitro study shows that fatigued lithium disilicate pressed zirconia and monolithic zirconia crowns have better fracture resistance than fluorapatite pressed zirconia and monolithic lithium disilicate crowns. [ABSTRACT FROM AUTHOR]

This study aimed to evaluate and compare the marginal and internal gap widths of lithium disilicate computer-aided design / computer-assisted manufacture (LDC) crowns and conventionally produced porcelain-fused-to-metal (PFM) crowns. A convenience sample of 21 patients treated with a single restoration was selected. PFM and LDC crowns were fabricated for each selected abutment tooth, following traditional crown preparation. Silicone replicas were produced, and internal gaps and marginal gaps were measured. Internal gaps were significantly larger for the axial and occlusal surfaces of LDC crowns than for those of PFM crowns (P < .001). Marginal gaps were not significantly different (P > .05). Both LDC crowns and PFM crowns showed clinically acceptable marginal fit. [ABSTRACT FROM AUTHOR]

This study analyzed the shear strength and fracture characteristics of the interface between zirconia samples and their veneering ceramic compared with a metal-ceramic and a lithium disilicate glass-ceramic control group together with an assessment of the possible relationship between the fracture characteristics and the recorded shear strength. The greatest shear strengths corresponded to the lithium disilicate glass-ceramic control group followed by the metal-ceramic control group, with lesser strengths in the zirconia groups. Since the fractographic study showed cohesive-type failure to predominate in the zirconia samples, it is concluded that improvements are needed in the veneering ceramic and liner used in zirconia restorations. [ABSTRACT FROM AUTHOR]

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This study aimed to evaluate the fracture resistance of monolithic single crowns made from zirconia (ZI), lithium disilicate (LS2), or feldspar ceramic (FC). Five groups of crowns representing a maxillary first molar were made with the appropriate dimensions according to the manufacturer’s instructions. The ZI and LS2 crowns were luted adhesively or cemented conventionally on a metal abutment tooth analog. The feldspar ceramic crowns were luted adhesively. All specimens underwent axial loading until fracture. The crowns in the ZI groups possessed the highest fracture resistance independent of the mode of fixation. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate 3D interfacial behavior, occlusal wear, and fracture resistance of endodontically treated molars restored with a full-crown restoration made with 2 different CAD/CAM materials after chewing simulation. Materials and Methods: 24 sound molars were selected and endodontically treated, shaped with PathFile and ProTaper Next (Dentsply Sirona) and filled using a warm condensation technique. Then a standardized MOD cavity was prepared and a fiber post (Panavia Post, Kuraray) supported build-up was performed. A standardized preparation for a complete crown with chamfer margin was done. Samples were then divided into two groups, according to restorative material: G1: zirconia-reinforced lithium silicate (Celtra DUO, Dentsply); G2: cubic zirconia (Katana, Kuraray). Preparations were scanned with Cerec Omnicam and restorations were milled with Cerec MXCL. The restorations were then luted (Panavia V5, Kuraray) following the manufacturer's instructions. After 7 days, the following tests were performed: micro-CT scan (Skyscan, Bruker); optical scan (Sinergiascan, Nobimetal). Fatigue and fracture resistance testing was performed with a chewing simulator (CS4.4, SD-Mechatronik). Thereafter, static fracture was tested using a universal testing machine (Instron) with a 6-mm-diameter steel sphere crosshead welded to a tapered shaft and applied to the specimens at a constant speed of 0.5 mm/min and an angle of 30 degrees to the long axis of the tooth. The load was applied perpendicular to the triangular crest of the palatal cusp. Samples were loaded until fracture; the maximum breaking loads were recorded in Newton (N). Each sample was scanned, radiographically and optically, before and after chewing. Data were imported into Mimics after smoothing and region growing; only external gaps were considered in the analysis. The STL optimal quality masks obtained were imported into Geomagic software for noise removal and volume calculation. Interfacial gap progression and occlusal wear data, expressed in mm3, and fracture resistance, expressed in N, were collected and statistically analyzed with two-way ANOVA (α < 0.05). Results: G1 showed a mean gap size of 0.43 mm3, while G2 had 0.39 mm3. Two-way ANOVA showed that interfacial gaps were not influenced by the material employed (p = 0.0674). Concerning the wear rate, lithium silicate showed a much larger volume reduction in mm3 than cubic zirconia (p = 0.00001). Fracture resistance (G1 = 1351,52; G2 = 1136,43) was significantly influenced by the material employed (p = 0.0001). Conclusion: The obtained results showed that cubic zirconia seems to better perform in the restoration of endodontically treated molars. Further studies are necessary to confirm present data. [ABSTRACT FROM AUTHOR]

The aim of this research was to evaluate internal and marginal adaptation of lithium disilicate partial crowns fabricated using IPS e.max Press and IPS e.max CAD systems.Forty maxillary first molars were divided into two groups. The margins were located above the cementoenamel junction mesially and below it distally. The adaptation of the restoration was evaluated by means of the silicone replica technique. The lowest marginal discrepancy was measured between the preparation margin on the enameland the IPS e.max Press specimens; the highest discrepancy was observed on the occlusal surface of the IPS e.max CAD specimens. Both systems tested demonstrated acceptable marginal discrepancies in vitro. [ABSTRACT FROM AUTHOR]

The aim of this randomized controlled trial was to evaluate the clinical performance of lithium disilicate fixed partial dentures (FPDs). Eighteen patients received lithium disilicate FPDs (study group), and 19 patients received porcelain-fused-to-metal FPDs (control). After 6 years, the survival probabilities were found to be 63% in the study group and 95% in the control group (log-rank test, P = .028). The data suggest that strict conditions should be considered before the use of lithium disilicate glass-ceramic for FPDs. [ABSTRACT FROM AUTHOR]

Aim: Color matching of the restoration to the adjacent teeth can be difficult due to the translucency of the ceramic and the visual exposure of the polymerized resin cement through the ceramic material. The aim of this study was to identify color differences between try-in pastes and the corresponding luting resin composites. Materials and methods: The materials tested were Variolink Veneer, Variolink Try-In, Variolink Esthetic LC, and Variolink Esthetic Try-In. Blocks of IPS e.max CAD were bisected along the vertical axis, producing specimens of different thicknesses. The surfaces to be evaluated were finely polished with a metallographic machine using 6000 grit SiC paper. The IPS e.max CAD specimens cemented with resin cement or with the try-in pastes were superimposed on a resin composite specimen reproducing the tooth structure. Evaluation of the color differences between the try-in pastes and polymerized cements of the same shade was performed with a spectrophotometer and a visual evaluation by three observers. Results: The measurements showed that for shades of Variolink Veneer and Variolink Esthetic LC resin cements and the corresponding try-in pastes there were significant color differences ΔE > 2.23). Among the groups of different thicknesses, specimens of 0.5-mm thickness exhibited the highest ΔE values, while the specimens of 2-mm thickness exhibited the lowest. Conclusions: The present study suggests that dentists should not rely on try-in pastes for the final color evaluation because they do not perfectly match the color shade of the cement used for the final luting of ceramic restorations. The originality of this study was the interpretation of color differences utilizing both a scientific spectrophotometer and visual observation. (Int J Esthet Dent 2018; 13:98-109) [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the load at fracture and influence of artificial aging of posterior teeth occlusal veneers ("table tops") made of two different ceramics.Materials and Methods: A total of 80 table tops were produced from feldspathic ceramic (VM) and zirconia-reinforced lithium silicate ceramic (CD) using computer-aided design/computer-assisted manufacturing (CAD/CAM). Half of the specimens from each ceramic were aged prior to the load test.Results: Mean ± standard deviation (SD) load at fracture was significantly higher for CD (1,571.1 N ± 297.0 N) than for VM (573.6 N ± 86.4 N) (P < .001). After aging, load at fracture increased significantly to 1,819.0 N (± 310.6 N) for CD and to 745.2 N (± 168.3 N) for VM.Conclusion: The use of zirconia-reinforced lithium silicate ceramic for molar nonprep table tops should be uncomplicated according to the high load-at-fracture values. Mechanical stability of either ceramic is not compromised by aging. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate the effect of premolar axial wall height on the retention of adhesive, full-coverage, computer-aided design/computer-assisted manufacture (CAD/CAM) restorations.Materials and Methods: A total of 48 premolar teeth randomized into four groups (n = 12 per group) received all-ceramic CAD/CAM restorations with axial wall heights (AWH) of 3, 2, 1, and 0 mm and 16-degree total occlusal convergence (TOC). Specimens were restored with lithium disilicate material and cemented with self-adhesive resin cement. Specimens were loaded to failure after 24 hours.Results: The 3- and 2-mm AWH specimens demonstrated significantly greater failure load. Failure analysis suggests a 2-mm minimum AWH for premolars with a TOC of 16 degrees.Conclusion: Adhesive technology may compensate for compromised AWH. [ABSTRACT FROM AUTHOR]

Materials and Methods: Sample size was calculated before experimentation (α = 0.05; β = 0.20; δ = 500.0; σ = 300.0). Thirty-six sound maxillary molars of comparable size received a standardized endodontic treatment and were randomly allocated to 4 experimental groups of 9 teeth each: Lava Ultimate endocrown (3M) without marginal relocation; Lava Ultimate endocrown with marginal relocation; Celtra DUO (Dentsply Sirona) without marginal relocation; Celtra DUO with marginal relocation. The marginal relocation procedure entailed the preparation of a mesial box of fixed dimensions and subsequent marginal relocation with a flowable composite (AP+ flow, Sweden & Martina) placed after self-etch adhesive procedures (Clearfil SE Bond 2, Kuraray). The endocrowns were obtained with the Cerec 3 CAD/CAM system (Dentsply Sirona) and luted with RelyX cement (3M). The restored teeth were subjected to thermomechanical aging (1,250,000 cycles, 1 Hz, 5-55°C) with a chewing machine (CS-4, Willytech) and were axially loaded to fracture with a universal testing machine (Quasar, Galdabini) equipped with a round-head stylus. A qualitative assessment of fracture types was performed. The groups were compared in terms of mean maximum load to fracture with a two-way ANOVA and Duncan's post-hoc test (α = 0.05). Results: In all the tested groups, the mean maximum loads were greater than the threshold of the masticatory forces. The greatest resistance values were registered in the Lava Ultimate endocrown without marginal relocation (1870.6 ± 279.9 N, p < 0.05), while the lowest in the Celtra DUO with marginal relocation (1289.5 ± 303.4 N, p < 0.05). Irrespective of the tested material, marginal relocation did not significantly reduce the resistance values (Lava Ultimate, p = 0.495; Celtra DUO, p = 0.929). The most prevalent type of restoration failure was non-restorable fracture. Conclusion: Marginal relocation in a proximal box did not affect the resistance to fracture of teeth restored with CAD/ CAM endocrowns. Athough both tested materials exhibited satisfactory results, lithium silicate seemed to show slightly inferior resistance to load compared to the tested composite. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate 3D interfacial behavior, occlusal wear, and fracture resistance of endodontically treated molars restored with an adhesive overlay with 2 different CAD/CAM materials after chewing simulation. Materials and Methods: 24 molars were selected and endodontically treated. Subsequently, a standardized MOD cavity was prepared, and a buildup was performed (Clearfil Majesty ES-2, Kuraray) after adhesive application (Clearfil SE Bond 2, Kuraray). A standardized overlay preparation was made. Samples were then divided in two groups, according to restorative materials: G1: Zirconia-reinforced lithium silicate (Celtra DUO, Dentsply); G2: Cubic zirconia (Katana, Kuraray). Preparations were scanned with Cerec Omnicam and restorations were milled with Cerec MXCL (Sirona). Restorations were then luted (Panavia V5, Kuraray) following the manufacturer instructions. After 7 days, the following tests were performed: 1. micro-CT scan (Skyscan, Bruker); 2. optical scan (Sinergiascan, Nobimetal); 3. fatigue and fracture resistance were performed with a chewing simulator (CS4.4, SD-Mechatronik). Afterwards, the restorations were subjected to static loading until fracture using a universal testing machine (Instron) with a 6-mm-diameter steel sphere crosshead welded to a tapered shaft and applied to the specimens at a constant speed of 0.5 mm/min at an angle of 30 degrees to the long axis of the tooth. The load was applied perpendicular to the triangular crest of the palatal cusp. Samples were loaded until fracture, and the maximum breaking loads were recorded in Newton (N). Each sample was scanned, radiographically and optically, before and after chewing. Data were imported into Mimics after smoothing and region growing; only external gaps were considered in the analysis. The STL optimal quality masks obtained were imported into Geomagic software for noise removal and volume calculation. Interfacial gap progression and occlusal wear data, expressed in mm3, as well as fracture resistance, expressed in N, were collected and statistically analyzed with two-way ANOVA (α = 0.05). Results: Two-way ANOVA showed that interfacial gap formation was not influenced by the material employed (p = 0.0657). Concerning the wear rate, lithium silicate showed a much larger volume reduction than cubic zirconia. Considering fracture resistance of overlays, there was no difference between the two materials (p = 0.0578). Conclusion: The obtained results showed that the restoration of endodontically treated molars with bonded overlays could be performed equally well with either lithium silicate or cubic zirconia. Further studies are necessary to confirm the present results. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the load-bearing capacity of monolithic lithium disilicate (LiDi - IPS e.max CAD) and novel ultratranslucent zirconia restorative systems of various compositions: 5Y-PSZ (5 mol% yttria-partially-stabilized zirconia) and 4Y-PSZ (4 mol% yttria-partially-stabilized zirconia); relative to a 3Y-TZP (3 mol% yttria-stabilized zirconia) control. Experiments were carried out with 10 disc specimens (Ø12 x 1 mm) per ceramic material. The zirconia intaglio surface (as machined) was sandblasted (50 µm Al2O3 at 2 bar), while LiDi was etched with 5% hydrofluoric acid for 20 seconds. The ceramic discs were then adhesively bonded onto a dentin-like substrate (G10, a high-pressure fiberglass material) using Multilink Automix cement and Monobond Plus primer, producing a ceramic/cement/dentinlike substrate trilayer structure. The bonded specimens were stored in water for 3 days at 37°C prior to a Hertzian indentation flexural radial fracture test. The plate-on-foundation theory was used to validate the load-bearing capacity of the trilayer systems based on the flexural tensile stress at the ceramic intaglio (cementation) surface--a cause for bulk fracture of ceramic onlays. The experiment data showed that, when bonded to and supported by a dentin-like substrate, the load-bearing capacity of LiDi (872 N) is superior to the 5Y-PSZ (715 N) and can even reach that of 4Y-PSZ (864 N), while 3Y-TZP still holds the highest load-bearing capacity (1,195 N). Theoretical analyses agree with experimental observations. The translucency of 5Y-PSZ approaches that of LiDi, and both are superior to 4Y-PSZ and 3Y-TZP. When adhesively bonded to and supported by dentin, LiDi exhibits similar load-bearing properties to 4Y-PSZ but much better than 5Y-PSZ. [ABSTRACT FROM AUTHOR]

Purpose: To compare the fracture resistance between bilayered zirconia/ fluorapatite and monolithic lithium disilicate heat-pressed crowns and characterize the mode of fracture failure. Materials and methods: Thirty crown samples were sequentially fitted on a mandibular right first molar metal replica of an ivory prepared molar tooth. The crown specimens were divided in three groups (A, B, and C; n = 10 for each group). Group A consisted of bilayered zirconia/fluorhapatite pressed-over crowns with standard design crown copings (0.7 mm uniform thickness), Group B of bilayered zirconia/fluorhapatite with anatomical design crown copings, and Group C of lithium disilicate monolithic crowns. The samples were then dynamically loaded under water for 100,000 cycles with a profile of 250 N maximum load at 1,000 N/s rate and 2.0 Hz frequency. Loading was performed with a steel ball (5 mm in diameter) coming into contact with the test crown, loading to maximum, holding for 0.2 s, unloading and lifting off 0.5 mm. The samples were then fractured under static loading, in order to determine the ultimate crown strength. Analysis of the recorded fracture load values was carried out with one-way analysis of variance (ANOVA) followed by Tukey tests. Fractured specimens were examined by stereomicroscopy and scanning electron microscopy. Results: The fracture loads measured were (N, means and standard deviations): Group A: 561.87 (72.63), Group B: 1,014.16 (70.18) and Group C: 1,360.63 (77.95). All mean differences were statistically significant (P < 0.001). Catastrophic fractures occurred in Group C, whereas mainly veneer fractures were observed in Groups A and B. Conclusion: In the present study, the heat-pressed monolithic lithium-disilicate crowns showed more fracture resistance than zirconia/fluorapatite pressed-over crowns. Within the bilayered groups, the anatomical zirconia coping design presented increased ceramic fracture resistance. [ABSTRACT FROM AUTHOR]