Search Results (589)

Using multifunctional dual-cure smart bioactive resin luting agents (DRLs) offers benefits in adhesive dentistry, but their optical stability remains a concern. Their pre-cured form is a shear-thinning structure with thixotropic gel-like behavior. The effect of their hydrophilicity and different thicknesses of nanoceramic hybrid on the final shade of milled esthetic restorations needs further investigation. This study examined how the optical function deterioration of dual-cure smart bioactive resin luting agents used to bond a CAD/CAM nano-ceramic hybrid composite would influence the restoration’s final shade at three different thicknesses. A nanoceramic hybrid composite (GD) was cut into blocks and grouped by thickness (0.8, 1.0, 1.5 mm). Ten blocks from each group were assigned to subgroups based on the DRL type: Panavia SA Universal (PN), Predicta Bioactive (PR), and ACTIVA BioACTIVE (AC). Color and whiteness changes after a 24 h/day (24 days) coffee immersion were analyzed using statistical methods (ANOVA and Tukey’s HSD for ΔE₀₀; Welch’s ANOVA and Games-Howell for ΔWI_D and ΔL*). DRL type significantly affected ΔE₀₀, ΔWI_D, and ΔL* (p < 0.001). All materials showed the least color change and optical function deterioration at a restoration thickness of 1.5 mm, which was below the acceptability threshold (AT). Despite PR’s bioactive functionality, it maintained its primary optical function with the least color change at GD thicknesses of 1.0 and 1.5 mm (p < 0.001). AC exhibited the greatest ΔE₀₀ above AT, especially at a thickness of 0.8 mm (p < 0.001). ΔL*, ΔE₀₀, and ΔWI_D varied significantly based on DRL type, GD thickness, and the interaction between DRL and thickness (p < 0.05). This suggests that although dual-cure smart DRLs containing bioactive glasses are advantageous, their optical function shifts may become more noticeable in thin, translucent restorations. Increasing the restoration thickness can help mitigate this by altering the optical pathway. Full article

Background: Patients with a thin gingival phenotype and a narrow buccal alveolar plate are highly susceptible to periodontal complications during orthodontic expansion. Traditional biomechanics often fail to maintain root control in thin alveolar housing. This report presents two clinical cases illustrating soft- and hard-tissue responses to a novel biomechanical approach, the Bone Protection System (BPS), designed to reduce buccal cortical overload during expansion. Case Presentation: Two adult patients with a thin gingival phenotype assessed by a standardized periodontal probe transparency test and narrow alveolar ridges underwent orthodontic expansion. Patient 1 was treated with the full BPS protocol in both arches. Patient 2 received BPS only in the maxilla, while the mandible was treated conventionally, creating an intra-individual control model under identical systemic conditions. Soft-tissue phenotype and cortical plate response were evaluated clinically and radiographically when applicable. Results: In Patient 1 clinically, the vestibular phenotype showed clear thickening and stabilization. In Patient 2, the maxillary arch treated with BPS exhibited progressive thickening of the vestibular phenotype, whereas the mandible treated conventionally presented thinning and increased translucency—features consistent with buccal compression in thin alveolar bone. No soft- or hard-tissue augmentation procedures were performed in either case. Conclusions: The Bone Protection System may contribute to improved periodontal safety during orthodontic expansion in thin-biotype patients by reducing buccal cortical loading and supporting adaptive soft-tissue and bone responses. Preliminary observations suggests that BPS has potential value for possibly expanding the biological limits of safe tooth movement. Further studies on larger cohorts are warranted. Full article

Patients with severe structural tooth wear present significant restorative challenges, including compromised oral function and the loss of essential anatomical landmarks such as marginal ridges, incisal edges, cusps, occlusal planes, and vertical dimension of occlusion (VDO). Successful management requires meticulous diagnosis, comprehensive treatment planning, and careful selection of restorative materials with appropriate biomechanical properties. Digital technologies have become integral to this process, particularly for enhancing diagnostic accuracy, material selection, and tooth preparation design within a fully digital workflow. This clinical case report illustrates a complete digital approach, beginning with an initial intraoral scan merged with a digital wax-up STL file featuring varying translucency dimensions to guide tooth preparation. This workflow enabled precise planning of tooth reduction, accurate assessment of available interocclusal space, and determination of material thickness requirements prior to irreversible procedures. Additionally, the integration of digital visualization improved patient communication, treatment predictability, and interdisciplinary collaboration. Overall, this case highlights the value of CAD/CAM technology in supporting complex oral rehabilitation for patients with advanced tooth wear, demonstrating its capacity to enhance efficiency, precision, and outcome quality in full-mouth zirconia ceramic restorations. Full article

This study aimed to compare the translucency values of anterior crowns fabricated with ultra-high-translucent (UHT) zirconia, low-translucent (LT) lithium disilicate (LDS), and LT zirconia-reinforced lithium silicate (ZLS) glass-ceramics. In total, 48 central incisor crowns (n = 12) were fabricated from IPS e.max CAD LT (IPS), Celtra Duo LT (CD), and GC Initial UHT zirconia (GC, GC1). A standard of 1.5 mm labial thickness of the crowns was determined for three groups (IPS, CD, GC), and 1 mm labial thickness was determined for GC1. The crowns’ translucency values were assessed in terms of the contrast ratio (CR). One-way ANOVA and Tamhane tests were used for analyzing the data. The mean CRs of GC1, GC, IPS, and CD specimens were 0.13 ± 0.01, 0.22 ± 0.01, 0.22 ± 0.04, and 0.29 ± 0.04, respectively. The CD group had significantly higher CR values than the other groups. The difference between the CR values of GC and IPS groups was not statistically significant. The GC1 group’s CR was significantly lower than the GC group. It is critical to select monolithic materials in order to achieve esthetic restorations, particularly for anterior teeth. The translucency of monolithic restorative materials was influenced by the type and the thickness of the material used. Full article

Background and Clinical Significance: Fourth-ventricular epidermoid cysts are rare intracranial lesions. They account for fewer than 1% of all primary brain tumors. Fourth-ventricular epidermoid cysts grow slowly because they are closely related to brainstem, cerebellum, and major blood vessels, so their treatment requires special caution. Because the cyst capsule attaches to functionally sensitive locations, complete removal is usually not possible without compromising some aspect of brain or spinal cord function. Surgical decision-making always involves weighing the need to remove the entire cyst against the potential loss of function of the affected area. The following case study describes how a patient was treated with a focus on the relationship between the cyst and surrounding anatomy, allowing for successful decompression with minimal risk to the patient’s neurologic status. Case Presentation: A young adult female patient was hospitalized with progressive truncal ataxia, disequilibrium and occipital headache accompanied by papilledema. Her physical examination disclosed significant dysfunction of the midline cerebellar region (SARA score = 18/40, ICARS score = 42/100), gaze-evoked nystagmus and bilaterally elevated grade II papilledema. MRI and MRA demonstrated a large, lobulated, nonenhancing, avascular mass located within the fourth ventricle, encroaching upon the dorsal medulla and obstructing both the foramen of Magendie and foramina of Luschka—findings typical of an epidermoid cyst. Microsurgical resection was accomplished via a median suboccipital craniectomy using a telovelar approach along the embryonic cerebellomedullary fissure to protect the integrity of the vermis and brainstem. The cyst contained layers of keratin embedded in a thin, translucent capsule. The capsule was carefully dissected away from the floor of the fourth ventricle. A very narrow band of capsule attached to the rhomboid fossa was intentionally spared to avoid damaging the cranial nerves. The patient had normal cerebrospinal fluid circulation restored and normal ventricular pulsation observed during surgery. Histopathology confirmed a benign epidermoid cyst consisting of keratinizing stratified squamous epithelium containing cholesterol clefts and laminated keratin debris. After surgery, the patient exhibited continuous neurological improvement including restoration of balance, disappearance of her headaches, and normalization of ocular pursuit. Sequential imaging studies were conducted post-operatively at one week, one month, three months, five months, and seven months to document stable decompression of the fourth ventricle, re-expansion of the fourth ventricle, and no evidence of cyst recurrence. Post-operative course was uncomplicated and the patient has remained free of symptoms and fully independent functionally at most recent follow-up. Conclusions: This case illustrates that when anatomically oriented, “maximal safe resection” can result in long-lasting decompression and clinically meaningful improvement in neurological function in patients with fourth-ventricular epidermoid cysts. Restoration of the patient’s natural cerebrospinal fluid pathway and preservation of neural interface relationships is more beneficial than pursuing aggressive removal of the cyst capsule. Although the risk of late recurrence is present even after nearly total removal, continuous radiologic monitoring is necessary to identify any recurrence. These experiences illustrate that with the principles of surgical restraint and anatomical guidance, there can be a balance between long-term stability and low operative risk. Full article

Three processes for the production of ceramics close to stoichiometric MgAl₂O₄ are benchmarked against each other. The traditional ceramic route is based on mostly crystalline starting powder, which is converted into ceramic via shaping and heat treatment (IKTS). The other two processes are based on glasses. Partial or complete crystallization without pressure (ISC) or complete crystallization with pressure (CAU) leads to (glass) ceramics. Spinel powder is mixed with various dopants (BaO, TiO₂, CaO and SrO), with the aim to reduce the grain size (IKTS). The doping results in a second, partly interfering phase, and the transmission decreases strongly due to absorption with increasing content of the added oxide. For the glass route without pressure (ISC), it is shown that a network-forming oxide (B₂O₃, TiO₂) is needed to produce the glasses. Compared to the starting glasses, the resultant glass ceramics suffer loss of transparency due to crystallization. Using the levitation furnace, it is possible to produce amorphous glass beads from MgAl₂O₄ enriched with 25 wt% SiO₂ without a container. The nanocrystalline ceramics synthesized from these glasses and the ISC glasses via the high-pressure route (CAU) are moderately transparent to translucent. Full article

Background/Objectives: Super translucent zirconia (ST zirconia) is increasingly used for esthetic restorations, but its optical stability after mechanical wear remains unclear. This study aimed to evaluate the effects of three finishing protocols—polishing, glazing, and staining followed by glazing (Chroma + Glaze)—on the color stability and translucency of ST zirconia after simulated toothbrushing. Methods: Sixty zirconia specimens (Vita YZ ST, shade A1) were fabricated and divided into three groups, namely Polished, Glazed, and Chroma + Glaze (n = 20 in each group). Color (L*, a*, b*) was measured using a spectrophotometer (VITA Easyshade V; VITA Zahnfabrik) before and after 10,000 brushing cycles (200 g load, 1.5 Hz). Translucency parameters (TP_ab, TP₀₀) were calculated, while color changes were assessed using CIELAB (ΔE_ab) and CIEDE2000 (ΔE₀₀) formulas. Data were analyzed using two-way ANOVA and Kruskal–Wallis tests (α = 0.05). Results: Treatment significantly affected translucency (H = 46.79, p < 0.001; H = 21.09, p < 0.001), indicating consistent differences among the three treatment groups. Bonferroni-adjusted post hoc comparisons showed that Chroma + Glaze exhibited significantly lower TP₀₀ values than Glaze in both measurements (p < 0.0001; p < 0.001), as well as lower values than Polished in both measurements (p < 0.0001; p = 0.0147, respectively). Kruskal–Wallis analysis revealed significant differences among finishing protocol groups for both ΔE_ab (H = 13.21, p < 0.0014) and ΔE₀₀ (H = 9.14, p = 0.0104), with Chroma + Glaze exhibiting the smallest ΔE values (ΔE₀₀ ≈ 0.33) below the perceptibility threshold. Conclusions: The finishing protocol significantly influences the optical behavior of ST zirconia after simulated wear. The Chroma + Glaze group demonstrated the highest color stability and lowest translucency, suggesting enhanced long-term esthetic performance. In contrast, polished zirconia showed greater color variation and an increase in translucency, indicating lower optical stability under brushing abrasion. Full article

This work highlights the feasible fabrication of translucent ceramics from un-doped and Nd³⁺-doped BaLaLiWO₆ (BLLW) and BaLaNaWO₆ (BLNW) cubic tungstates using the Spark Plasma Sintering (SPS) method. Ceramics were sintered using pure-phase, homogeneous powders with submicron particle sizes, obtained via the solid-state reaction method. The present study investigated the microstructural, structural, and spectroscopic properties of both un-doped and Nd³⁺-doped sintered specimens. All the ceramic materials exhibited certain drawbacks that significantly contributed to their low transparency in both sample types. However, initial spectroscopic tests on sintered translucent ceramics doped with Nd³⁺ ions revealed promising properties, comparable to those of the powdered samples. Therefore, we believe that producing higher-quality ceramics would improve their spectroscopic properties. For that, further optimization of the manufacturing conditions is necessary. Full article

The genus Tortula is one of the most diverse and morphologically complex groups within Pottiaceae. This study presents both morphological and phylogenetic evidence for the recognition of a new species, T. murciana, within the T. subulata complex. The new species is distinguished by a unique combination of traits, including a translucent leaf lamina, upper laminal cells with 3–7 simple, wart-like papillae (verrucae), and middle laminal cells 16–24(35) µm wide, that are much higher near the costa than at the leaf margins. The ventral epidermal cells of the costa at mid-leaf are quadrate to spherical and inflated. The costa is robust, up to 140 µm wide at mid-leaf and papillose on the dorsal side. The apical cell of the apiculus is typically hyaline and often deciduous. The leaf border is usually absent or poorly developed. The basal membrane of the peristome is 0.70–0.90 mm long, with a reticulate pattern where the lumina are delimited by strongly developed muri ornamented with globose clusters of ear-like lobes (auricles). Phylogenetic analysis of the nuclear ITS region places T. murciana within the T. subulata complex, clearly distinguishing it from T. mucronifolia and T. subulata var. graeffii, with which it shares the closest morphological similarity. Although most specimens can be identified morphologically, some remain difficult to name, making them a semi-cryptic species. The new species is formally diagnosed, described, illustrated, and compared to similar taxa. A key to all species in the complex is also provided. Full article

This study investigated real-time polymerisation kinetics and mechanical properties under accelerated ageing of novel universal bulk-fill composites incorporating reversible addition–fragmentation chain transfer (RAFT) agent ß-allyl sulfone, designed for anterior and posterior applications. Five bulk-fill composites were tested: Tetric Plus Fill and Tetric Plus Flow (new universal composites); their predecessors, Tetric PowerFill and Tetric PowerFlow (Ivoclar); and RAFT-free Ecosite Bulk Fill (DMG). Specimens were polymerised for 3 s (~3000 mW/cm²), 10 s (~1200 mW/cm²), or 20 s (~1200 mW/cm²). Degree of conversion (DC) was monitored during and after curing, with mechanical testing after 24 h and after thermal cycling. DC and maximum polymerisation rate at 4 mm depth were significantly lower than at 0.1 mm for all materials and curing times. Three-second curing accelerated the polymerisation rate at both depths. Except for Ecosite cured for 3 or 10 s as RAFT-free material, DC ratios at 4 mm exceeded 80% of surface values. Tetric Plus Fill and Ecosite exhibited the highest flexural strength after 24 h, while PowerFill and Ecosite showed the highest flexural modulus at 24 h and after thermal cycling. Rapid curing did not compromise mechanical properties after 24 h, except for PowerFlow, the composite with the lowest filler vol%, but negatively affected both flowable composites after ageing. Thermal cycling reduced flexural strength in most tested conditions, but all materials and curing conditions more than satisfied the ISO 4049 requirements. The new simplified universal composite Plus Fill has a higher DC and improved polymerisation kinetics compared to its predecessor, PowerFill. Rapid curing is not recommended for the material without RAFT agents. Full article

Mono-material multilayer polypropylene films were developed as light barrier structures through the incorporation of mineral-filled composite layers. Trilayer films with different layer arrangements were fabricated by thermocompression from polypropylene-based films containing 0, 1 and 5 wt.% of talc and kaolinite. A monolayer polypropylene film of equivalent total thickness was used as a control. Structural, thermal, mechanical, optical, and gas barrier properties were evaluated for all films fabricated. A well-defined trilayer structure was confirmed by SEM. FTIR analysis demonstrated negligible thermo-oxidation, with no thermal-degradation during processing. Improved thermal stability and a slight modification in crystallinity were evidenced by TGA and DSC, respectively. XRD revealed the predominance of the α-form crystalline phase and a preferential polymer crystal orientation associated with the particle presence. Regarding mechanical behavior, enhanced stiffness and tensile strength without loss of sealability or puncture resistance were observed. Trilayer films exhibited significantly reduced UV and visible light transmittance, while maintaining adequate translucency, making them suitable for photosensitive packaging applications. Gas permeabilities remained nearly unchanged, confirming that the barrier performances were preserved. Overall, these mono-material multilayer composites films offer a promising and recyclable alternative to conventional multi-material light barrier packaging, combining improved UV protection, mechanical robustness, and environmental compatibility. Full article

Ceramic materials have gained outstanding popularity in restorative and prosthetic dentistry due to their combination of high biocompatibility, mechanical durability, and natural esthetics. Among the most important developments in this field are the use of zirconia- and glass-based ceramics for various applications. Zirconia ceramics, especially yttria-stabilized tetragonal zirconia polycrystals (Y-TZP), are famous for their high mechanical strength, transformation toughening, chemical stability, and great biocompatibility. Newer generations like 4Y/5Y-PSZ zirconia have addressed the demand for higher translucency, meeting esthetic requirements. Glass–ceramics, including lithium disilicate and leucite-reinforced systems, are preferred for their optical properties, etchability, and strong adhesive bonding. Their microstructure provides a balance between strength and esthetics, supporting minimally invasive restorations with long-term clinical success. Both zirconia and glass–ceramics exhibit favorable biological responses, including low plaque accumulation and soft tissue compatibility. The goal of ongoing research is to overcome limitations, such as low-temperature degradation, bonding limitations, and surface durability. Also, to improve mechanical performance and functional integration, new approaches include 3D printing, graded materials, nanostructuring, and bioactive coatings. This review aims to provide a comprehensive overview of the composition, properties, clinical applications, current limitations, and future perspectives of zirconia- and glass-based ceramics in restorative dentistry. Full article

Background/Objectives: Zirconia-reinforced lithium silicate (ZLS) is a glass–ceramic that combines the translucency of lithium disilicate with the enhanced strength provided by dispersed zirconia crystals. Evidence on the mechanical behavior of ZLS implant-supported crowns remains limited. This study evaluated the fracture resistance of posterior monolithic ZLS crowns and analyzed the influence of cement type and artificial aging. Methods: Forty ZLS crowns (Celtra™ Duo) were fabricated, cemented onto straight titanium abutments and assigned to four groups (n = 10) according to cement type (adhesive or self-adhesive) and aging (500,000 cycles at 150 N). Specimens underwent axial load-to-fracture testing using a universal testing machine. Data were analyzed with Student’s t-tests and Kruskal–Wallis tests (α = 0.05). Results: Mean fracture resistance was 1625.46 ± 340.02 N. Although adhesive cement showed higher mean values than self-adhesive cement, no statistically significant differences were found (p = 0.102). Artificial aging also produced no significant reduction in fracture resistance (p = 0.674). All groups exceeded the physiological posterior occlusal forces. Conclusions: Monolithic ZLS crowns cemented onto titanium abutments demonstrated high fracture resistance under axial loading. Within the limitations of this in vitro design, neither cement type nor mechanical aging significantly affected performance. These findings support the mechanical feasibility of ZLS for posterior implant-supported single crowns, although further studies including thermomechanical aging and oblique loading are required. Full article

Background: This study evaluated the influence of various decontamination protocols after salivary contamination on the micro-shear bond strength (µSBS) between monolithic high-translucency zirconia and resin cement. Methods: A total of 81 multilayer (ML) monolithic–translucent zirconia discs of 10 mm diameter and 2 mm thickness (DD cubeX2 ML, Dental Direkt) were fabricated, sintered, and polished using silicon–carbide papers. The bonding surfaces were treated with 50-μm Al₂O₃ using a Renfert sandblaster at 0.3 MPa for 20 s. Fifty samples were randomly assigned to five groups (n = 10). A control group consisted of clean, uncontaminated samples, while the other four groups were contaminated and cleaned using water, sodium hypochlorite, phosphoric acid + ethanol, or Ivoclean, respectively. Resin cement cylinders (Panavia V5, Kuraray Noritake) were bonded onto the zirconia surfaces. The µSBS was evaluated after simulated ageing using a universal testing machine. Failure modes were analysed by light microscopy. Surface morphology was evaluated using a field emission scanning electron microscope (SEM), and the chemical surface was assessed with X-ray photoelectron spectroscopy (XPS) and Fourier Transform Infrared (FTIR) Spectroscopy. Surface wettability was assessed through contact angle measurements. One-way ANOVA with Tukey’s HSD was used to compare µSBS between groups. Results: Among the tested groups, the control group exhibited the highest µSBS value (59.5 ± 4.2 MPa), followed by Ivoclean (56.7 ± 4.8 MPa), phosphoric acid + ethanol (46.8 ± 4.7 MPa), and sodium hypochlorite (41.1 ± 5.7 MPa), with the lowest value observed with water (33.5 ± 6.3 MPa). All groups exhibited adhesive failure, with no sign of cohesive or mixed failures. SEM analysis showed no effect on zirconia crystallinity or sandblasting, while Ivoclean left residual zirconium oxide particles. Furthermore, XPS and FTIR analysis revealed favourable chemical changes after Ivoclean treatment, correlating with improved bonding performance. Contact angle measurements confirmed greater surface wettability in the Ivoclean group, resulting in strong bond strength. Conclusions: Ivoclean significantly increased the resin–zirconia bond strength after saliva contamination, showing more reliable results compared to others. Phosphoric acid + ethanol showed the second-highest mean strength, while water showed the least effectiveness. Full article

Background: Gastroesophageal reflux disease (GERD) exposes restorative materials to gastric acid, which may compromise their esthetic and optical properties. Limited evidence exists regarding the performance of different CAD/CAM ceramics under acidic challenges. Methods: Forty CAD/CAM ceramic discs were prepared (n = 10 per group): high-translucency zirconia (Z; Ceramill Zolid Gen-X), lithium disilicate (E; IPS e.max CAD), zirconia-reinforced lithium silicate (S; VITA Suprinity), and hybrid ceramic (C; Cerasmart 270). Specimens were immersed in simulated gastric acid (0.06 M HCl, pH 1.2) at 37 °C for 96 h. Color difference (ΔE) and translucency parameter (ΔTP) were recorded before and after immersion using a spectrophotometer. Data were analyzed using one-way ANOVA with Tukey’s post hoc test (α = 0.05). Results: All materials exhibited changes in color and translucency after acidic immersion. Group Z demonstrated the lowest ΔE values, indicating the best color stability, whereas group C showed the highest ΔE and a significant reduction in ΔTP. Groups E and S revealed moderate but clinically acceptable changes. Intergroup differences were statistically significant (p < 0.05). Conclusions: Exposure to simulated gastric acid as in (GERD) resulted in measurable alterations in the optical properties of CAD/CAM ceramic materials. The extent of color change and translucency loss differed among the materials tested. High-translucency zirconia (Z) exhibited the greatest stability, while hybrid ceramic (C) showed the most pronounced changes. Zirconia-reinforced lithium silicate (S) and lithium disilicate (E) demonstrated moderate alterations, falling between these two extremes. Full article