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To evaluate and compare the effect of tooth preparation designs and different CADCAM. materials on stress distribution and Weibull survival probability of endocrowns. applied to root canal-treated lower first permanent molar using the 3D finite element. analysis method. A root canal-treated lower first permanent molar was prepared for endocrowns with a. butt joint or with a ferrule design by placing, circumferentially, a 1-mm wide shoulder. finish line. The prepared molar was scanned for the two designs and modeled on a 3D. Finite element model. Monolithic zirconia (IPS e.max ZirCAD MT, FCZ), lithium. disilicate (IPS e.max CAD, EX), and nano-ceramic resin composite (Lava Ultimate, LU). CAD-CAM materials were used for each preparation to design the virtual endocrown. A. total of six models were built according to the different tooth preparation designs and. endocrown materials. An occlusal load of 600 N and a transverse load of 20 N in. magnitude that simulates the average occlusal load was directed toward the occlusal. surfaces. von Mises and maximum principle values were evaluated Weibull risk-ofrupture. analysis was used to analyze the survival probability of the restorations and. tooth in the different models. The highest von Mises were found in the butt joint design for FCZ, EX, and LU (45.3. MPa, 35.2 MPa, and 24.2 MPa, respectively) compared to the ferrule design for the. same materials (42.6 MPa, 31.2 MPa, and 23.6 MPa, respectively). For von Mises. stress distribution in the remaining part of tooth structure (dentin), the highest stresses. were found in LUFerrule which was closely similar to LUButt joint (135.4 MPa and. 134.7 MPa, respectively), followed by EXFerrule and FCZFerrule (132.2 MPa and. 131.7 MPa, respectively), while the lowest stresses were found in EXButt joint and. FCZButt joint (129.0 MPa and 128.4 MPa, respectively). Shear stresses within the. resin cement were the highest in FCZ and EX compared to LU. EX was found to be the. most reliable material with the highest survival probability, while FCZ showed the. lowest survival probability according to the Weibull risk-of-fracture results. Materials with high elastic modulus transfer more stresses to the endocrown and less. to the remaining tooth structure. Endocrown tooth preparation with ferrule design has. better stress distribution and magnitude compared to the butt joint design. [ABSTRACT FROM AUTHOR]

The widespread adoption of distributed generation (DG) is changing the operation of distribution networks. To increase the control of power flows and avoid the detriments of DG intermittency, active distribution networks (ADN) emerge as a feasible solution. In this paper, we propose a convex model for ADN expansion planning. Four active network management (ANM) schemes are considered: DG active power curtailment, DG reactive power control, on-load tap changer (OLTC) tap adjustment, and shunt compensation device control. The problem is formulated as a mixed integer second-order cone programming problem (MISOCP) using the distflow equations and second-order cone relaxations (SOCR). By scenario analysis, we address the uncertainty associated with power demand, renewable generation, and electricity prices. The proposed model is used to study the benefits of different combinations of ANM schemes to a modified IEEE 33-bus system and compare them with the individual benefits of each scheme. The results indicate that ANM schemes can reduce total network costs, reduce losses, delay network reinforcement, and improve the voltage profile. In addition, some combinations of schemes develop synergies in which the combined economic benefits are greater than the sum of the individual benefits. [Display omitted] [ABSTRACT FROM AUTHOR]

This study examines the effect of two light-curing protocols from a LED polywave light curing unit (LCU) on water sorption, solubility, and hygroscopic expansion of fast and conventional bulk-fill resin-based composites (RBCs) aged in distilled water for 120 d. Three bulk-fill RBCs materials were studied: Tetric PowerFill® (fast photo-polymerised composite) (TPF), Tetric EvoCeram bulk-fill (EVO), and GrandioSo x-tra bulk-fill (GSO) (conventiona l photo-polymerised composites). Specimens were prepared within a 3D-printed resin mold (8-mm diameter x 4-mm height) and light-cured from one side only with 2 modes of polywave LCU (Bluephase® PowerCure): 3 s mode and for 20 s in "Standard" mode. Water sorption and solubility were measured at fixed time intervals for 120 d of distilled water storage, then reconditioned to dry to measure desorption for 75 d, all at 37 ± 1 °C. Hygroscopic (volumetric) expansion was recorded at the same time intervals up to 120 d. Data were analysed through SPSS using Two-way ANOVA, One-way ANOVA, independent t-tests, and Tukey's post-hoc correction tests (p < 0.05). TPF, when irradiated for 3 s demonstrated minimal water sorption (0.83%), solubility (1.01 μg/mm3), and least volumetric expansion (1.64%) compared to EVO and GSO. While EVO showed the highest water sorption (1.03%) and solubility (1.95 μg/mm3) at 3 s. GSO had the lowest sorption (0.67%) and (0.56%) in 3 s and 20 s protocols, respectively. Nevertheless, all the sorption and solubility data were within the ISO 4049 limits. For TPF, fast (3 s) polymerisation did not increase either water sorption or solubility, compared with 20 s irradiation. However, with the two comparative bulk-fill composites, fast cure increased water sorption by 15–25% and more than doubled solubility. These findings were consistent with the lesser volumetric expansions observed for Tetric PowerFill at both the fast and standard protocols, indicating its relative stability across polymerisation protocols. [ABSTRACT FROM AUTHOR]

This 3D finite element analysis study aimed to investigate the effect of reinforcing CAD-CAM bars on stress distribution in various components of a posterior composite bridge. A virtual model mimicking the absence of an upper second premolar was created, featuring class II cavity preparations on the proximal surfaces of the adjacent abutment teeth surrounding the edentulous space. Five distinct finite element analysis (FEA) models were generated, each representing a CAD-CAM reinforcing bar material: 3-YTZP (IPS. emax ZirCAD MO; Zr), lithium disilicate (IPS e.max CAD; EX), nano-hybrid resin composite (Grandio Blocs; GB), Fibre-reinforced composite (Trilor; Tri), and polyetheretherketone (PEEK). A veneering resin composite was employed to simulate the replacement of the missing premolar (pontic). In the FEA, an axial force of 600 N and a transverse load of 20 N were applied at the center of the pontic. Subsequently, maximum von Mises (mvM) and maximum principal stresses (σmax) were computed across various components of the generated models. Additionally, shear stresses at the interface between the CAD-CAM bars and the veneering resin composite were determined. CAD-CAM materials with high modulus of elasticity, such as Zr and EX, exhibited the highest mvM stresses and shear stresses while transferring the lowest stress to the veneering resin composite in comparison to other materials. Conversely, PEEK demonstrated the lowest mvM stresses but produced the highest stresses within the veneering resin composite. There was a uniform distribution of mvM stresses in the remaining tooth structure among all groups, except for a noticeable elevation in the molar region of Zr and EX groups. Reinforcing CAD-CAM bar materials with a high modulus of elasticity, such as Zr and EX, may result in debonding failures at the connector sites of posterior composite bridges. Conversely, GB, PEEK, and Tri have the potential to cause fracture failures at the connectors rather than debonding. [ABSTRACT FROM AUTHOR]

This study investigated effects of the different emittance-mode protocols from three light curing units (LCUs): (i) a Laser (Monet); (ii) a quad-wave (PinkWave); (iii) a conventional LED (Elipar S10) on the temperature rise (ΔT) and degree of conversion (DC) when photo-curing fast or conventional bulk-fill resin-based composites (RBC). The aim was to correlate ΔT and DC, and the radiant exposure delivered to RBC specimens. A 3D-printed resin mold of 4 mm depth was filled with two bulk-fill RBCs: Tetric PowerFill® (fast photo-polymerised composite) (TPF) or Tetric EvoCeram® Bulk-Fill (EVO). Three LCUs were used: (i) Monet laser for 1 s and 3 s (MONET-1 s, MONET-3 s); (ii) PinkWave quad-wave used for 3 s in Boost mode (PW-3 s) and for 20 s in standard mode (PW-20 s); (iii) Elipar S10 for 5 s (S10–5 s) and for 20 s in standard mode (S10–20 s). 2-dimensional temperature maps were obtained before, during and for 60 s after the LCU had turned off using a thermal imaging camera. Thermal changes were analysed at five depths: (0, 1, 2, 3, and 4 mm from the top surface of the RBC). The maximum temperature rise (T max) and the mean temperature rise (ΔT) were determined. Cylindrical-shaped specimens were prepared from each material using a stainless-steel split mold (4 × 4 mm) and light-cured with the same protocols. The DC was measured for 120 s and at 1 h after LCU had turned off using Fourier Transform Infrared Spectroscopy (FTIR). Data were analysed using Three-way ANOVA, One-way ANOVA, independent t-tests, and Tukey post-hoc tests (p < 0.05). Radiant exposures delivered by the various irradiation protocols were between 4.5–30.3 J/cm2. Short exposure times from MONET-1 s and PW-3 s delivered the lowest radiant exposures (4.5 and 5.2 J/cm2, respectively) and produced the lowest ΔT and DC. The longer exposure times in the standard modes of PW-20 s, S10–20 s, and MONET-3 s produced the highest T max , ΔT, and DC for both composites. The ΔT range among composites at different depths varied significantly (31.7–49.9 °C). DC of TPF ranged between 30–65% and in EVO between 15.3–56%. TPF had higher T max, ΔT for all depths and DC compared to EVO, across the LCU protocols (p < 0.05), except for PW-20 s and MONET-3 s. The coronal part of the restorations (1–2 mm) had the highest ΔT. There was a positive correlation between ΔT and DC at 4-mm depth after 120 s Longer, or standard, exposure times of the LCUs delivered greater radiant exposures and had higher DC and ΔT compared to shorter or high-irradiance protocols. The fast photo-polymerised RBC had comparatively superior thermal and conversion outcomes when it received a high irradiance for a short time (1–5 s) compared to the conventional Bulk-Fill RBC. [ABSTRACT FROM AUTHOR]

To evaluate properties of fiber-reinforced-composites (FRC) containing Bis-EMA/UDMA monomers but identical dispersed phase (60% wt BaSi glass power +10% wt E-glass fibre). A control (Group A), monomer mixture comprising 60% Bis-GMA, 30% TEGDMA, and 10% PMMA (typical FRC monomers) was used. The following monomer mass fractions were mixed: 50% bis-GMA plus 50% of different ratios of Bis-EMA+UDMA to produce consistent formulations (Groups B-E) of workable viscosities was also studied. Flexural strength (FS), fracture toughness (K IC), water sorption (SP), solubility (SL) and hygroscopic expansion (HE) were measured. FS and K IC specimens were stored for 1, 7 d, and 30 d in water at 37 °C. SP/SL specimens were water-immersed for 168d, weighed at intervals, then dried for 84 d at 37 °C. To analyze differences in FS, and K IC , a two-way ANOVA and Tukey post-hoc tests (α = 0.05) were conducted. For SP/SL, and HE, one-way ANOVA with subsequent Tukey post-hoc tests (α = 0.05) were utilized. FS and K IC for groups A, D, E decreased progressively after 1 d. Groups B and C (highest amounts of Bis-EMA) did not decrease significantly. The modified matrix composites performed significantly better than the control group for SP and HE. The control group outperformed the experimental composites only for SL with up to 250% higher SL for group E (6.9 μg/mm) but still below the maximum permissible threshold of 7.5 μg/mm. Significance: composites with highest amounts of Bis-EMA showed improved hydrolytic stability and overall enhancement in several clinically-relevant properties. This makes them potential candidates for alternative matrices to a semi-interpenetrating network in fiber-reinforced composites. [ABSTRACT FROM AUTHOR]

Part 1 of this study investigates the influence of zirconia types, chimney heights, and gingival heights on the strength of the zirconia-abutment-interface. Part 2 extends the analysis to include adhesive brands and macro-retentions. In Part 1, the study utilized three zirconia types (700 MPa, 1000 MPa, 1200 MPa) to fabricate 234 screw-retained zirconia crowns with varying chimney heights (3.5 mm, 4.1 mm, 5 mm) and gingival heights (0.65 mm, 1.2 mm, 3 mm) of the titanium abutments. All adherend surfaces underwent sandblasting with aluminum oxide before cementation with a specific resin cement. In Part 2, the investigation of 240 screw-retained zirconia crowns focused on a single zirconia type (1000 MPa) with chimney heights of 3.5 mm and 5 mm and a gingival height of 0.65 mm of the titanium abutments, cemented with three different resin cements. All adherent surfaces underwent sandblasting with aluminum oxide before cementation, whereas 120 out of 240 abutments received additional macro retentions. Storage in water at 37 °C for 24 h preceded the tensile test. The study revealed a substantial impact of chimney height and zirconia type on the bond strength of the zirconia-abutment-interface. Neither adhesive brands nor macro retentions significantly impacted the bond strength. Fracture incidence was significantly influenced by gingival height and zirconia type in part 1, whereas in part 2 smaller chimney heights correlated with a higher fracture incidence. This study contributes insights into the complex interplay of factors influencing the zirconia-abutment-interface. The results provide a foundation for refining clinical approaches, emphasizing the importance of chimney height and zirconia type in achieving successful anterior gap implant restorations. [ABSTRACT FROM AUTHOR]

This study evaluates the potential for osseointegration and remodeling of customized dental implants made from Titanium-Hydroxyapatite Functionally Graded Material (Ti-HAP FGM) with optimized geometry, using the finite element method (FEM). The study utilized CT scan images to model and assemble various geometrical designs of dental implants in a mandibular slice. The mechanical properties of Ti-HAP FGMs were computed by varying volume fractions (VF) of hydroxyapatite (0–20%), and a bone remodeling algorithm was used to evaluate the biomechanical characteristics of the ultimate bone configuration in the peri-implant tissue. The findings of the FEA reveal that osseointegration improves with changes in the density and mechanical properties of the bone surrounding Ti-HAP implants, which are influenced by the varying VF of hydroxyapatite in the FGM. Increasing the hydroxyapatite fraction improves osseointegration, and appropriate length and diameter selection of Ti-HAP dental implants contribute to their stability and longevity. [Display omitted] [ABSTRACT FROM AUTHOR]

The current dental resin composites often suffer from polymerization shrinkage, which can lead to microleakage and potentially result in recurring tooth decay. This study presents the synthesis of a novel monomer, (3,9-diethyl-1,5,7,11-tetraoxaspiro[5,5]undecane-3,9-diyl)bis(methylene) bis((2-(3-(prop-1-en-2-yl)phenyl)propan-2-yl)carbamate) (DDTU-IDI), and evaluates its effect in the formulation of low-shrinkage dental resin composites. DDTU-IDI was synthesized through a two-step reaction route, with the initial synthesis of the required raw material monomer 3,9-diethyl-3,9-dihydroxymethyl-1,5,7,11-tetraoxaspiro-[5,5] undecane (DDTU). The structures were confirmed using Fourier-transform infrared (FT-IR) spectroscopy and hydrogen nuclear magnetic resonance (1HNMR) spectroscopy. Subsequently, DDTU-IDI was incorporated into Bis-GMA-based composites at varying weight percentages (5, 10, 15, and 20 wt%). The polymerization reaction, degree of conversion, polymerization shrinkage, mechanical properties, physicochemical properties and biocompatibility of the low-shrinkage composites were thoroughly evaluated. Furthermore, the mechanical properties were assessed after a thermal cycling test with 10,000 cycles to determine the stability. The addition of DDTU-IDI at 10, 15, and 20 wt% significantly reduced the polymerization volumetric shrinkage of the experimental resin composites, without compromising the degree of conversion, mechanical and physicochemical properties. Remarkably, at a monomer content of 20 wt%, the polymerization shrinkage was reduced to 1.83 ± 0.53%. Composites containing 10, 15, and 20 wt% DDTU-IDI exhibited lower water sorption and higher contact angle. Following thermal cycling, the composites exhibited no significant decrease in mechanical properties, except for the flexural properties. Significance. DDTU-IDI has favorable potential as a component which could produce volume expansion and increase rigidity in the development of low-shrinkage dental resin composites. The development of low-shrinkage composites containing DDTU-IDI appears to be a promising strategy for reducing polymerization shrinkage, thereby potentially enhancing the longevity of dental restorations. • A new monomer "DDTU-IDI" was synthesized through a simple two-step reaction route. • The composites containing 10 wt% ∼ 20 wt% DDTU-IDI exhibited low polymerization shrinkage. • The addition of DDTU-IDI effectively maintained the mechanical properties of the composites. • The composites containing DDTU-IDI showed favorable resistance to aging. • The novel composites may be a promising dental restoration material in reducing the occurrence of secondary caries. [ABSTRACT FROM AUTHOR]

Customization and the production of patient-specific devices, tailoring the unique anatomy of each patient's jaw and facial structures, are the new frontiers in dentistry and maxillofacial surgery. As a technological advancement, additive manufacturing has been applied to produce customized objects based on 3D computerized models. Therefore, this paper presents advances in additive manufacturing strategies for patient-specific devices in diverse dental specialties. This paper overviews current 3D printing techniques to fabricate dental and maxillofacial devices. Then, the most recent literature (2018–2023) available in scientific databases reporting advances in 3D-printed patient-specific devices for dental and maxillofacial applications is critically discussed, focusing on the major outcomes, material-related details, and potential clinical advantages. The recent application of 3D-printed customized devices in oral prosthodontics, implantology and maxillofacial surgery, periodontics, orthodontics, and endodontics are presented. Moreover, the potential application of 4D printing as an advanced manufacturing technology and the challenges and future perspectives for additive manufacturing in the dental and maxillofacial area are reported. Additive manufacturing techniques have been designed to benefit several areas of dentistry, and the technologies, materials, and devices continue to be optimized. Image-based and accurately printed patient-specific devices to replace, repair, and regenerate dental and maxillofacial structures hold significant potential to maximize the standard of care in dentistry. [ABSTRACT FROM AUTHOR]

To assess visually and quantitatively the contributions of the adhesive layer photopolymerization and the subsequent resin composite increment to spatio-temporal maps of temperature at five different cavity locations, subjected to two irradiance curing protocols: standard and ultra-high. Caries-free molars were used to obtain 40, 2 mm thick dentin slices, randomly assigned to groups (n = 5). These slices were incorporated within 3D-printed model cavites, 4 mm deep, restored with Adhese® Universal bonding agent and 2 mm thick Tetric® Powerfill resin composite, and photocured sequentially, as follows: G1: control-empty cavity; G2: adhesive layer; G3 composite layer with no adhesive; and G4 composite layer with adhesive. The main four groups were subdivided based on two curing protocols, exposed either to standard 10 s (1.2 W/cm2) or Ultra high 3 s (3 W/cm2) irradiance modes using a Bluephase PowerCure LCU. Temperature maps were obtained, via a thermal imaging camera, and numerically analyzed at 5 locations. The data were analyzed using two-way ANOVA followed by multiple one-way ANOVA, independent t-tests and Tukey post-hoc tests (α = 0.05). T max , ΔT, T int (integrated area under the curve) and time-to-reach-maximum-temperature were evaluated. Two-way ANOVA showed that there was no significant interaction between light-curing time and location on the measured parameters (p > 0.05), except for the time-to-reach-maximum-temperature (p < 0.05). Curing the adhesive layer alone with the 10 s protocol resulted in a significantly increased pulpal roof temperature compared to 3 s cure (p < 0.05). Independent T-tests between G3 and G4, between 3 s and 10 s, confirmed that the adhesive agent caused no significant increases (p > 0.05) on the measured parameters. The ultra-high light-curing protocol significantly increased ΔT in composite compared to 10 s curing (p < 0.05). When the adhesive layer was photocured alone in a cavity, with a 2 mm thick dentin floor, the exothermal release of energy resulted in higher temperatures with a 10 s curing protocol, compared to a 3 s high irradiance. But when subsequently photocuring a 2 mm layer of composite, the resultant temperatures generated at pulpal roof location from the two curing protocols were similar and therefore there was no increased hazard to the dental pulp from the immediately prior adhesive photopolymerization, cured via the ultra-high irradiation protocol. [ABSTRACT FROM AUTHOR]