Complete genome sequence and phylogenetic analysis of a newly discovered fusagra-like virus infecting Carica papaya in Ecuador.

A new fusagra-like virus infecting papaya (Carica papaya L.) was genetically characterized. The genome of the virus, provisionally named "papaya sticky fruit-associated virus" (PSFaV), is a single molecule of double-stranded RNA, 9,199 nucleotides (nt) in length, containing two discontinuous open reading frames. Pairwise sequence comparisons based on complete RNA-dependent-RNA-polymerase (RdRp) sequences revealed identity of 79.4% and 83.3% at the nt and amino acid (aa) level, respectively, to babaco meleira-like virus (BabMelV), an uncharacterized virus sequence discovered in babaco (Vasconcellea x heilbornii) in Ecuador. Additional plant-associated viruses with sequence identity in the 50% range included papaya meleira virus (PMeV) isolates from Brazil. Phylogenetic analysis based on the amino acid sequences of the capsid protein (CP), RdRp, and CP-RdRp fusion protein genes placed PSFaV in a group within a well-supported clade that shares a recent ancestor with Sclerotium rolfsii RNA virus 2 and Phlebiopsis gigantea mycovirus dsRNA 2, two fungus-associated fusagraviruses. Genomic features and phylogenetic relatedness suggest that PSFaV, along with its closest relative BabMelV, represent a species of novel plant-associated virus classified within the recently established family Fusagraviridae.

Renal impairment is prevalent in pediatric NAFLD/MASLD and associated with disease severity.

OBJECTIVES: Renal impairment is prevalent in adults with nonalcoholic fatty liver disease (NAFLD/metabolic dysfunction associated steatotic liver disease [MASLD]) and is associated with increased mortality. Pediatric data are limited. Our objective was to determine the prevalence of hyperfiltration or chronic kidney disease (CKD) in children with NAFLD/MASLD and determine links with liver disease severity. METHODS: Data from children who had previously participated in prospective, multicenter, pediatric studies by the Nonalcoholic Steatohepatitis Clinical Research Network (NASH-CRN) were collected. Renal function was determined using the calculated glomerular filtration rate (cGFR). Hyperfiltration was defined as cGFR > 135 mL/min/1.73m2, while CKD stage 2 or higher as cGFR < 90 mL/min/1.73 m2. Renal dysfunction progression was defined as transition from normal to hyperfiltration or to CKD stage ≥ 2, or change in CKD by ≥1 stage. Multinomial logistic regression models were used to determine the prevalence of CKD and independent associations between CKD and liver disease severity. RESULTS: The study included 1164 children (age 13 ± 3 years, 72% male, 71% Hispanic). The median cGFR was 121 mL/min/1.73 m2; 12% had CKD stage 2-5, while 27% had hyperfiltration. Hyperfiltration was independently associated with significant liver fibrosis (odds ratio: 1.45). Baseline renal function was not associated with progression in liver disease over a 2-year period (n = 145). Renal dysfunction worsened in 19% independently of other clinical risk factors. Progression of renal impairment was not associated with change in liver disease severity. CONCLUSIONS: Renal impairment is prevalent in children with NAFLD/MASLD and hyperfiltration is independently associated with significant liver fibrosis. Almost 1/5 children have evidence of progression in renal dysfunction over 2 years, not associated with change in liver disease severity. Future assessments including additional renal impairment biomarkers are needed.

Solar photovoltaic panel production in Mexico: A novel machine learning approach.

This study examines the potential for widespread solar photovoltaic panel production in Mexico and emphasizes the country's unique qualities that position it as a strong manufacturing candidate in this field. An advanced model based on artificial neural networks has been developed to predict solar photovoltaic panel plant metrics. This model integrates a state-of-the-art non-linear programming framework using Pyomo as well as an innovative optimization and machine learning toolkit library. This approach creates surrogate models for individual photovoltaic plants including production timelines. While this research, conducted through extensive simulations and meticulous computations, unveiled that Latin America has been significantly underrepresented in the production of silicon, wafers, cells, and modules within the global market; it also demonstrates the substantial potential of scaling up photovoltaic panel production in Mexico, leading to significant economic, social, and environmental benefits. By hyperparameter optimization, an outstanding and competitive artificial neural network model has been developed with a coefficient of determination values above 0.99 for all output variables. It has been found that water and energy consumption during PV panel production is remarkable. However, water consumption (33.16 × 10-4 m3/kWh) and the emissions generated (1.12 × 10-6 TonCO2/kWh) during energy production are significantly lower than those of conventional power plants. Notably, the results highlight a positive economic trend, with module production plants generating the highest profits (35.7%) among all production stages, while polycrystalline silicon production plants yield comparatively lower earnings (13.0%). Furthermore, this study underscores a critical factor in the photovoltaic panel production process which is that cell production plants contribute the most to energy consumption (39.7%) due to their intricate multi-stage processes. The blending of Machine Learning and optimization models heralds a new era in resource allocation for a more sustainable renewable energy sector, offering a brighter, greener future.

Fracture resistance of partial and complete coverage veneers and ceramic crowns for maxillary central incisors.

STATEMENT OF PROBLEM: Minimally invasive treatments have gained popularity in recent years. However, research comparing the fracture resistance of lithium disilicate partial coverage veneer restorations with that of ceramic crowns is lacking. PURPOSE: The purpose of this in vitro study was to evaluate and compare the fracture resistance of lithium disilicate restorations fabricated for preparations of various designs. The designs included veneer preparations with finish lines in the upper, middle, and lower third of the facial surface and ceramic crown preparations with margins in the lower third of the facial surface. All restorations were designed and fabricated using a chairside digital workflow. MATERIAL AND METHODS: Four maxillary right central incisor typodont teeth were prepared for partial coverage veneer preparation with the margin in the upper middle third of the facial surface (PU1/3); partial coverage veneer preparation with margin in lower middle third of the facial surface (PL1/3); complete coverage veneer preparation (CV) with margin in the cervical region; and ceramic crown (CC) preparation. Each preparation was scanned, and 15 casts were 3D printed from each scan. A total of 60 lithium disilicate restorations were fabricated (n=15 per group) using a chairside computer-aided design and computer-aided manufacturing (CAD-CAM) system (Primescan and MCXL). The different restorations were cemented to the 3D printed testing dies with a photopolymerizable resin cement. The specimens were artificially aged with 10 000 thermal cycles between 5 and 55 °C with a dwell time of 30 seconds and were loaded to failure using a universal testing machine. The maximum load to fracture was analyzed using a 1-way ANOVA and post hoc Tukey honestly significant difference (HSD) test (α=.05). Additionally, the fracture patterns of the specimens were evaluated with a stereomicroscope for descriptive purposes. RESULTS: The mean fracture resistance of the chairside CAD-CAM lithium disilicate veneers and ceramic crowns was statistically different depending on the design of the restoration (P<.05). Group CC demonstrated the highest fracture resistance values (1440.66 N), followed by CV (929.8 N) and PU1/3 (756.13 N). The lowest value was for PL1/3 (532.4 N). CONCLUSIONS: The fracture resistance measured for the maxillary central incisor partial coverage veneers with margins in the middle third of the facial surface appear capable of resisting average occlusal forces. However, these veneers demonstrated lower fracture resistance values when compared with complete coverage veneers. Further, lithium disilicate crowns demonstrated higher fracture resistance than veneers, irrespective of their design.

Verifying the seating of a 3D-printed removable die using elastomeric matrices: A dental technique.

Computer-aided design and computer-aided manufacturing systems enable digital designing and 3-dimensional (3D) printing of definitive casts with removable dies. However, the fit of the removable dies should be without interferences for their accurate positioning in the cast. Given that the accuracy of additive manufacturing depends on design- and manufacturing-related factors, verifying the accuracy of the position of 3D-printed removable dies in their cast is essential to fabricate positionally accurate definitive prostheses, which would enable minimal or no laboratory and clinical adjustments. This dental technique article presents a straightforward approach to verify the seating of a 3D-printed removable die by using verification matrices made of a polyvinylsiloxane interocclusal registration material.

The 3D-printed shell complete denture technique: Simplifying prosthodontic diagnosis prior to implant planning.

Traditionally, artificial teeth arrangements or the definitive complete dentures are used to establish important prosthodontic parameters such as the occlusal plane orientation, vertical dimension, and the incisal edge position. The relationship of these elements with the underlying bony structures is commonly evaluated using advanced planning protocols such as the dual scan technique. This technique article presents an uncomplicated alternative approach to establish these parameters intraorally using a 3D-printed shell complete denture generated from a 3D scan of the patient's existing complete denture.

Expediting the Rehabilitation of Severely Resorbed Ridges Using a Combination of CAD-CAM and Analog Techniques: A Case Report.

With the life expectancy increasing, there is a growing need for prosthetic dental treatments to restore the oral health, function, and quality of life of edentulous patients. Presently, only a few articles are available describing the oral rehabilitation of patients with severely resorbed ridges with milled complete dentures. This clinical case report provides a straightforward protocol consisting of a combination of analog and digital techniques for the rehabilitation of edentulous patients with severely resorbed ridges with milled fixed and removable complete dentures. This technique permits the minimization of the number of appointments, improves patient comfort, allows for the digital archiving of important clinical data, and permits the manufacture of prostheses with improved mechanical properties. These favorable outcomes were achieved by using the patient's existing PMMA complete denture as a custom tray for a final impression with light-bodied Polyvinylsiloxane. Subsequently, the resulting models were digitized, and a digital complete denture was designed and manufactured in an expedited manner using CAD-CAM techniques. Therefore, this case report highlights the potential of CAD/CAM technology to predictably restabilize oral functions and improve patients' quality of life.

Functions of Melatonin during Postharvest of Horticultural Crops.

Melatonin, a tryptophan-derived molecule, is endogenously generated in animal, plant, fungal and prokaryotic cells. Given its antioxidant properties, it is involved in a myriad of signaling functions associated with various aspects of plant growth and development. In higher plants, melatonin (Mel) interacts with plant regulators such as phytohormones, as well as reactive oxygen and nitrogen species including hydrogen peroxide (H2O2), nitric oxide (NO) and hydrogen sulfide (H2S). It shows great potential as a biotechnological tool to alleviate biotic and abiotic stress, to delay senescence and to conserve the sensory and nutritional quality of postharvest horticultural products which are of considerable economic importance worldwide. This review provides a comprehensive overview of the biochemistry of Mel, whose endogenous induction and exogenous application can play an important biotechnological role in enhancing the marketability and hence earnings from postharvest horticultural crops.

GK-1 effectively reduces angiogenesis and prevents T cell exhaustion in a breast cancer murine experimental model.

Breast cancer is the leading malignancy in women worldwide, both in terms of incidence and mortality. Triple-negative breast cancer (TNBC) is the type with the worst clinical outcomes and with fewer therapeutic options than other types of breast cancer. GK-1 is a peptide that in the experimental model of the metastatic 4T1 breast cancer has demonstrated anti-tumor and anti-metastatic properties. Herein, GK-1 (5 mg/kg, i.v.) weekly administrated not only decreases tumor growth and the number of lung macro-metastases but also lung and lymph nodes micro-metastases. Histological analysis reveals that GK-1 reduced 57% of the intra-tumor vascular areas, diminished the leukemoid reaction's progression, and the spleens' weight and length. A significant reduction in VEGF-C, SDF-1, angiopoietin-2, and endothelin-1 angiogenic factors was induced. Moreover, GK-1 prevents T cell exhaustion in the tumor-infiltrating lymphocytes (TILs) decreasing PD-1 expression. It also increased IFN-γ and granzyme-B expression and the cytotoxic activity of CD8+ TILs cells against tumor cells. All these features were found to be associated with a better antitumor response and prognosis. Altogether, these results reinforce the potential of GK-1 to improve the clinical outcome of triple-negative breast cancer immunotherapy. Translation research is ongoing towards its evaluation in humans.

Diversity, distribution, and expression of opsin genes in freshwater lakes.

Microbial rhodopsins are widely distributed in aquatic environments and may significantly contribute to phototrophy and energy budgets in global oceans. However, the study of freshwater rhodopsins has been largely limited. Here, we explored the diversity, ecological distribution, and expression of opsin genes that encode the apoproteins of type I rhodopsins in humic and clearwater lakes with contrasting physicochemical and optical characteristics. Using metagenomes and metagenome-assembled genomes, we recovered opsin genes from a wide range of taxa, mostly predicted to encode green light-absorbing proton pumps. Viral opsin and novel bacterial opsin clades were recovered. Opsin genes occurred more frequently in taxa from clearwater than from humic water, and opsins in some taxa have nontypical ion-pumping motifs that might be associated with physicochemical conditions of these two freshwater types. Analyses of the surface layer of 33 freshwater systems revealed an inverse correlation between opsin gene abundance and lake dissolved organic carbon (DOC). In humic water with high terrestrial DOC and light-absorbing humic substances, opsin gene abundance was low and dramatically declined within the first few meters, whereas the abundance remained relatively high along the bulk water column in clearwater lakes with low DOC, suggesting opsin gene distribution is influenced by lake optical properties and DOC. Gene expression analysis confirmed the significance of rhodopsin-based phototrophy in clearwater lakes and revealed different diel expressional patterns among major phyla. Overall, our analyses revealed freshwater opsin diversity, distribution and expression patterns, and suggested the significance of rhodopsin-based phototrophy in freshwater energy budgets, especially in clearwater lakes.

A novel function of the tomato CALCINEURIN-B LIKE 10 gene as a root-located negative regulator of salt stress.

Climate change exacerbates abiotic stresses like salinization, negatively impacting crop yield, so development of strategies, like using salt-tolerant rootstocks, is crucial. The CALCINEURIN B-LIKE 10 (SlCBL10) gene has been previously identified as a positive regulator of salt tolerance in the tomato shoot. Here, we report a different function of SlCBL10 in tomato shoot and root, as disruption of SlCBL10 only induced salt sensitivity when it was used in the scion but not in the rootstock. The use of SlCBL10 silencing rootstocks (Slcbl10 mutant and RNAi line) improved salt tolerance on the basis of fruit yield. These changes were associated with improved Na+ and K+ homoeostasis, as SlCBL10 silencing reduced the Na+ content and increased the K+ content under salinity, not only in the rootstock but also in the shoot. Improvement of Na+ homoeostasis in Slcbl10 rootstock seems to be mainly due to induction of SlSOS1 expression, while the higher K+ accumulation in roots seems to be mainly determined by expression of LKT1 transporter and SlSKOR channel. These findings demonstrate that SlCBL10 is a negative regulator of salt tolerance in the root, so the use of downregulated SlCBL10 rootstocks may provide a suitable strategy to increase tomato fruit production under salinity.

Carfilzomib-based antibody mediated rejection therapy in pediatric kidney transplant recipients.

BACKGROUND: To date, the evidence for proteasome-inhibitor (PI) based antibody mediated rejection (AMR) therapy has been with the first-generation PI bortezomib. Results have demonstrated encouraging efficacy for early AMR with lesser efficacy for late AMR. Unfortunately, bortezomib is associated with dose-limiting adverse effects in some patients. We report use of the second generation proteosome inhibitor carfilzomib for AMR treatment in two pediatric patients with a kidney transplant. METHODS: The clinical data on two patients who experienced dose limiting toxicities from bortezomib were collected along with their short- and long-term outcomes. RESULTS: A two-year-old female with simultaneous AMR, multiple de novo DSAs (DR53 MFI 3900, DQ9 MFI 6600, DR15 2200, DR51 MFI 1900) and T-cell mediated rejection (TCMR) completed three carfilzomib cycles and experienced stage 1 acute kidney injury after the first two cycles. At 1 year follow up, all DSAs resolved, and her kidney function returned to baseline without recurrence. A 17-year-old female also developed AMR with multiple de novo DSAs (DQ5 MFI 9900, DQ6 MFI 9800, DQA*01 MFI 9900). She completed two carfilzomib cycles, which were associated with acute kidney injury. She had resolution of rejection on biopsy and decreased but persistent DSAs on follow-up. CONCLUSIONS: Carfilzomib treatment for bortezomib-refractory rejection and/or bortezomib toxicity may provide DSA elimination or reduction, but also appears to be associated with nephrotoxicity. Clinical development of carfilzomib for AMR will require a better understanding of efficacy and development of approaches to mitigate nephrotoxicity.

First report of Pectobacterium brasiliense causing banana soft rot in Ecuador.

Banana (Musa spp.) is the most economically important crop in Ecuador, with exports representing 35% of the agricultural GDP of the country. It covers 230,000 hectares, mostly concentrated in three coastal provinces, Guayas, Los Ríos, and El Oro. Between July and September 2022, disease symptomatic banana cv. Williams plants were observed in commercial plantations located in two parishes in the province of Guayas (Naranjito and Lorenzo de Garaicoa) and one parish in the province of Santo Domingo de los Tsáchilas (La Concordia), with an incidence that ranged from 5% to 15%. Symptoms included soft rot of the pseudostem and rhizome decay, characterized by a fetid odor. Three symptomatic pseudostems from each location were collected, washed with running water to remove any debris, and dried with absorbent paper. From the lesion of each pseudostem, seven pieces of 2 cm² were taken, surface-sterilized, and macerated in 9 ml of sterile peptone water (0.1% w/v). The macerate was diluted three fold in sterile water, plated on nutrient agar, and incubated at 30°C for 24 h. Eight randomly picked colonies, with convex elevation and creamy white color, were isolated on nutrient agar. Each of the bacterial isolates was biochemically profiled by the Biolog system (Biolog Inc., USA) and identified as Pectobacterium. Three isolates, one from each parish (FP220416, FP220694, and FP220904), were selected for testing Koch's postulates and further identification. Sequences from fragments of the 16S, dnaA, gapA and gyrB genes were obtained from these isolates, following the protocols used by Dobhal et al. (2020) and Boluk et al. (2020), showing 98.1-99.0%, 98.2%, 99.7-99.8%, and 98.4-98.9% identitity, respectively, with sequences from the P. brasiliense type strain LMG_21371 (Acc. number JQOE00000000). The obtained sequences were deposited in GenBank with the following accession numbers: OR392417, OR371545,OR371546, OR727281, OR727282, and OR739074-OR739080. Using BEAST v.1.10.4 (Suchard et al.,2018), a bayesian multilocus phylogenetic tree was built with multiple sequence alignments of dnaA, gapA, ang gyrB from 22 P. brasiliense isolates and 2 P. aquaticum isolates used as outgroup. The phylogenetic analysis showed that the Ecuadorian isolates cluster with P. brasiliense BF20, isolated from Opuntia ficus-indica in México and are closely related with the type strain. Pathogenicity tests were conducted through syringe infiltration with 1 ml of 1 × 10^8 CFU ml-1 bacterial suspensions. Each of the three characterized isolates were inoculated into the pseudostems of five healthy 4-month-old banana plants of the Williams cultivar. Negative control plants were infiltrated with sterile distilled water. The plants were incubated at 25°C and 74% relative humidity. Black lesions started to appear 11 days after inoculation and 5 weeks after inoculation plants showed clear symptoms of soft rot of the pseudostem, including fetid odor associated with plant tissue decomposition. Control plants remained symptom-free. Bacteria were re-isolated only from symptomatic pseudostems and identified as P. brasiliense with specific primers Pb1F and Pb1R. Soft rot of banana caused by different enterobacteria including Dickeya zeae, Erwinia carotovora, and Erwinia chrysanthemi hasve been previously reported (Jingxin et al. 2022, Arun et al. 2012, Loganathan, et al. 2019). This is the first report of P. brasiliense causing soft rot of banana in Ecuador, the biggest exporter of the fruit in the world.

Do we still need to screen our patients?-Orthopaedic scoring based on motion tracking.

PURPOSE: Orthopaedic scores are essential for the clinical assessment of movement disorders but require an experienced clinician for the manual scoring. Wearable systems are taking root in the medical field and offer a possibility for the convenient collection of motion tracking data. The purpose of this work is to demonstrate the feasibility of automated orthopaedic scorings based on motion tracking data using the Harris Hip Score and the Knee Society Score as examples. METHODS: Seventy-eight patients received a clinical examination and an instrumental gait analysis after hip or knee arthroplasty. Seven hundred forty-four gait features were extracted from each patient's representative gait cycle. For each score, a hierarchical multiple regression analysis was conducted with a subsequent tenfold cross-validation. A data split of 70%/30% was applied for training/testing. RESULTS: Both scores can be reproduced with excellent coefficients of determination R2 for training, testing and cross-validation by applying regression models based on four to six features from instrumental gait analysis as well as the patient-reported parameter 'pain' as an offset factor. CONCLUSION: Computing established orthopaedic scores based on motion tracking data yields an automated evaluation of a joint function at the hip and knee which is suitable for direct clinical interpretation. In combination with novel technologies for wearable data collection, these computations can support healthcare staff with objective and telemedical applicable scorings for a large number of patients without the need for trained clinicians.

Detection of mandibular flexure with a dental plaster verification device: A clinical report with video recording.

Mandibular flexure is a phenomenon characterized by a reduction of the arch width caused by the action of various muscular groups involved during mastication. When flexure is pronounced and teeth or dental implants are rigidly splinted, mandibular flexure leads to a biomechanical environment detrimental to the longevity of the restoration. This clinical report presents the use of a dental plaster device as a diagnostic tool to determine the extent of mandibular flexure in an edentulous patient treated with a mandibular fixed complete denture.

Rehabilitation of a patient with mandibular flexure using contemporary glass-infiltrated high performance CAD-CAM polymers: A clinical report with 1-year follow-up.

Mandibular flexure is a phenomenon generated by the action of the muscles of mastication and other muscles in the head and neck region which can lead to prosthetic and biological complications such as pain, material fracture, and bone loss around dental implants. To avoid such complications, dividing the mandibular prostheses into 3 short-span prostheses or sectioning at the midline has been suggested. This clinical report presents the management of an edentulous patient with clinically detectable mandibular flexure treated with a 1-piece metal-free complete arch implant-supported prosthesis.

Using the foundation restoration as a blueprint: An uncomplicated approach to retrofitting crowns to existing removable partial dentures using CAD-CAM technology.

Removable partial dentures have been used to rehabilitate partially edentulous patients for decades. A challenging but commonly encountered procedure is retrofitting a crown to an existing removable partial denture. Several techniques have been proposed for fabricating these complex prostheses, some involving the intraoral application of polymers to the abutment tooth or making impressions of the preparation with the removable prosthesis seated. The present technique presents an approach that simplifies the design and fabrication of retrofitted crowns for fractured abutment teeth needing foundation restorations. This approach involves the implementation of computer-aided design and computer-aided manufacturing technology to record and utilize the contours of the foundation restoration established intraorally as a blueprint for the retrofitted crown.

Positional trueness of three removable die designs with different root geometries manufactured using stereolithographic 3D printing.

STATEMENT OF PROBLEM: Three-dimensional (3D) printed casts are a suitable alternative to dental stone casts. Contemporary dental design computer programs permit designing definitive casts with removable dies with different root geometries and retention mechanisms. Studies on the positional trueness of 3D-printed removable dies with different root geometries are lacking. PURPOSE: The purpose of this in vitro study was to investigate the 3D displacements of three 3D-printed removable die designs with different root geometries. MATERIAL AND METHODS: The digital file of a dental stone alveolar cast with root-form removable dies (MOD UJ IV Fixed Prosthetics; Ivoclar AG) was used as a reference to create 3 removable die and alveolar cast designs (Root Form, RF; Conical, CON; Cylindric, CYL) with different root geometries in 2 dental design computer programs (DentalCAD 3.1 Rijeka; exocad; GmbH; InLab CAD 22.0; Dentsply Sirona). 3 equidistant Ø1-mm spheres (C, Cervical; M, Middle; O, Occlusal) were designed on the buccal surface of the coronal portion of the removable die to evaluate their displacement. A total of 45 alveolar casts with 45 removable dies were fabricated using a stereolithographic 3D printer (Form 3; Formlabs); each die group consisted of 15 specimens. After fabrication and postprocessing, the specimens were scanned, and their digital files were analyzed in a metrology-grade computer program to evaluate the displacement of the removable dies with respect to the position of the die in the master reference file. Subsequently, the data were analyzed using a 3-way analysis of variance (ANOVA) followed by step-down Bonferroni-corrected pairwise comparisons (α=.05). RESULTS: Two statistically significant 2-way interactions were detected between the independent variables, die design and direction (P<.001), and location and direction (P<.001). The post hoc analysis identified significant differences between the displacement values of RF and CYL (P<.001) and RF and the CON (P<.001) designs on the Y axis. The measured displacements were statistically different between the C and O locations on the Y axis (P=.001) and the M and O locations on the Z axis (P=.006). CONCLUSIONS: The root geometry of a 3D-printed removable die and alveolar cast can affect seating, and variable degrees of tipping of the removable die can be seen. The seating and congruence of the removable die with the interocclusal space and relationships observed intraorally should be confirmed before adjusting indirect restorations.

Effect of resin cement selection on fracture resistance of chairside CAD-CAM lithium disilicate crowns containing virgilite: A comparative in vitro study.

STATEMENT OF PROBLEM: Studies on the fracture performance of a recently introduced computer-aided design and computer-aided manufacturing (CAD-CAM) lithium disilicate ceramic containing virgilite with different cements are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the fracture resistance of crowns made of a recently introduced chairside CAD-CAM lithium disilicate containing virgilite cemented with different types of adhesive luting cement. MATERIAL AND METHODS: Sixty complete coverage crowns for a maxillary right central incisor were milled out of a lithium disilicate with virgilite (CEREC Tessera) (n=48) and a traditional lithium disilicate (e.max CAD) (n=12) using a chairside CAD-CAM system (Primescan). The central incisor tooth preparation included a 1.5-mm incisal reduction, a 1.0-mm axial reduction, and a 1.0-mm chamfer finish line. The restorations were bonded with different types of resin cement to 3D printed dies of the tooth preparation and were divided into 5 groups (n=12 per group): e.max CAD with Multilink Automix (E.Mu); Tessera with Multilink Automix (T.Mu); Tessera with Calibra (T.Ca); Tessera with Unicem (T.Un); and Tessera with Speedcem (T.Sp). The cemented restorations were stored in water for 30 days and then loaded until they were fractured in compression. The load at fracture was analyzed with a 1-way analysis of variance (ANOVA) and the honestly significant difference (HSD) Tukey test (α=.05). RESULTS: The mean fracture resistance of traditional lithium disilicate and virgilite lithium disilicate anterior crowns significantly differed depending on the type of resin cement used (P<.05). Group E.Mu displayed the highest values (946.35 ±155 N), followed by group T.Un (819.59 ±232 N), group T.Sp (675.52 ±153 N), and group T.Mu (656.95 ±193 N). The lowest values were displayed by group T.Ca (567.94 ±184 N). CONCLUSIONS: The fracture resistance of lithium disilicate containing virgilite and traditional lithium disilicate crowns cemented with the same cement displayed statistically similar values. However, significant differences were observed when the virgilite lithium disilicate crowns were cemented with different types of adhesive luting cement. The crowns in the T.Ca group displayed the lowest fracture resistance.

Fracture resistance of zirconia surveyed crowns with four different occlusal rest seat designs.

PURPOSE: To determine the fracture resistance of chairside computer-aided design and computer-aided manufacturing (CAD-CAM) zirconia surveyed crowns for a mandibular first molar without occlusal rest and with four different rest seat designs. MATERIALS AND METHODS: Seventy CAD-CAM zirconia 4Y-PSZ (IPS e.max ZirCAD MT for CEREC A1, C15, Ivoclar Vivadent) crowns (14 specimens/group) were designed and fabricated with a dental chairside CAD-CAM system (CEREC PrimeScan, and CEREC MCXL Dentsply Sirona). The restorations were divided into groups according to the following rest seat designs: (1) Surveyed crown without rest seat, (2) surveyed crowns with disto-occlusal rest seat, (3) surveyed crowns with disto-occlusal extended rest seat, (4) surveyed crowns with interproximal rest seat, and (5) continuous rest seat. Crowns were treated with a primer system (Monobond Plus, Ivoclar Vivadent) and cemented using resin luting cement (Multilink Automix, Ivoclar Vivadent) to resin-printed dies (Grey Resin V4, FormLabs). Subsequently, the crowns were subjected to 200,000 load cycles at 1 Hz with 20 N force and then loaded with a steel indenter until fracture. The test results were analyzed with one-way Analysis of Variance (ANOVA) and HSD Tukey post-Hoc test. RESULTS: The mean fracture resistance of surveyed crowns without and with different rest seats was significantly different from each other. Surveyed crowns with no rest seat displayed the highest resistance (4238 N) followed by crowns with continuous rest seat (3601 N), crowns with disto-occlusal extended rest seat (3283 N), and crowns with disto-occlusal rest seat (3257 N). Crowns with interproximal rest seat displayed the lowest fracture resistance (2723 N). CONCLUSIONS: Surveyed crowns without rest seats had a higher fracture resistance than crowns with rest seats Surveyed crowns with interproximal rest seats presented the lowest fracture resistance among all rest seat designs. Crowns with disto-occlusal rest seats, disto-occlusal extended rest seats, and continuous rest seats displayed similar fracture resistance.