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BACKGROUND: The accuracy of dental crowns is crucial for their longevity and effectiveness. OBJECTIVE: This study aims to investigate how the precision of crowns is affected by two different fabrication methods, either subtractive (milling) or additive (3D printing), within computer-aided design/computer-aided manufacture (CAD/CAM) technology. METHODS: A standardised digital scan of a maxillary first molar with a shoulder margin (.stl file) was used to design and fabricate crowns through both subtractive (milling) and additive (3D printing) processes. The crowns' marginal and internal fits were assessed comprehensively. Statistical analysis, including two-way ANOVA and independent t-tests, revealed significant differences in fitting accuracy between the two methods. RESULTS: Crowns produced via 3D printing demonstrated superior fitting with minimal marginal (14 ± 5 μ m) and internal discrepancies (22 ± 5 μ m) compared to milling (marginal: 22 ± 4 μ m, internal: 23 ± 3 μ m), indicating a statistically significant advantage in precision ( p ⁢ s ⩽ 0.022 for marginal fit). CONCLUSION: The findings suggest that 3D printing may offer a more accurate alternative to milling in the fabrication of digital dental prostheses, potentially revolutionising the field with its enhanced precision capabilities. [ABSTRACT FROM AUTHOR]

The availability of intraoral scanners has significantly increased in recent years. Numerous studies have investigated the accuracy of different intraoral scanners; however, limited evidence is available concerning the effects of the accuracy of IOSs on the fit of zirconia crowns. This study aimed to assess and compare the accuracy of four intraoral scanners in terms of trueness and to analyse its impact on the trueness, as well as the internal and marginal adaptations of zirconia crowns fabricated from these scanners. Ten sound maxillary left first premolar teeth prepared to receive zirconia crowns were used in this research. First, the teeth were scanned with a lab scanner (inEos X5, Dentsply Sirona) as a reference. Each tooth was scanned serially with the following IOSs: PrimeScan, Medit i700 wireless, TRIOS5, and Helios 600. Five monolithic zirconia crowns were fabricated for each tooth, one crown per scanner. The trueness of the tested scanners was determined by the superposition of each IOS's scanned data with the reference scanner's scanned data by metrology software (Geomagic Control X) and presented as a colour-coded map. The accuracy of the fabricated zirconia restoration was assessed by superimposing the scanned data of the intaglio of the crown fabricated from each intraoral scanner with the intaglio of the crown fabricated from the lab scanner (reference crown). The internal and marginal gaps of the crowns were then measured via the silicone replica technique, followed by a 3D evaluation of the replica by the software. The data were analysed using one-way ANOVA, Tukey's HSD test. Pearson's correlation test. The tested IOSs revealed significant differences in trueness (p<0.05). Primescan, Medit i700, and their corresponding crowns showed the highest trueness among the groups, while Helios 600 and its corresponding crowns showed the lowest trueness. The lowest internal and marginal gaps were observed in the crowns fabricated from Primescan and Medit i700, whereas the highest marginal and internal gaps were observed in the crowns fabricated from Helios 600. A moderately positive correlation was found between the tested IOSs' trueness and the fabricated restorations' marginal and internal adaptations. Significant differences in trueness between the IOSs were found, which substantially impacted the trueness and fitness of the produced crowns. [ABSTRACT FROM AUTHOR]

The study was conducted to evaluate the fracture strength of endo-crown restorations fabricated from different CAD/CAM materials luted to maxillary premolars. Fifty endodontically treated maxillary premolars were prepared in a standardized method to be restored with endo-crown restorations using different materials. They were divided into 5 main groups (n =10) according to the material used to fabricate endo-crown restorations: Endo-crowns of Group A (Vita Enamic), Group B (Cerasmart 270), Group C (IPS e. max CAD), Group D (Celtra Duo), Group E (Zirconia). After proper surface treatment for all endo-crowns, the restorations were cemented using dual-cure adhesive (RelyX Ultimate) resin cement (shade A1). All specimens were left undisturbed for an hour in a bench set before being preserved in distilled water for a full day after being removed from the holding apparatus. Universal testing machine was used to evaluate the fracture strength of each material. The study found significant differences in fracture strength between five materials, with Zirconia endo-crowns having the highest strength (2900.62±103.851N) and Celtra Duo endo-crowns having the lowest (771.66±31.159N). This suggests that Zirconia endo-crowns are the most robust. Within the limitations of this in-vitro study, we could conclude that: In terms of fracture strength, Zirconia endo-crowns had the highest fracture strength among all groups, while Celtra duo endo- crowns had the lowest fracture strength. [ABSTRACT FROM AUTHOR]

• Lithium disilicate and advanced lithium disilicate CAD/CAM ceramics displayed the highest translucency and color stability. • Thickness significantly affected color stability, with 0.5 mm thickness showing the least color change unlike 1.5 mm thickness. • The duration of exposure to staining solutions also impacted color changes, with 30 days causing the most significant shift. • Coffee and tea induced more pronounced reductions in translucency and color stability among all tested CAD/CAM ceramics. • Novel advanced lithium disilicate CAD/CAM ceramics show that it can be used to fabricate esthetic restorations as dental veneers, all ceramic restorations, and endocrown of optimum shade matching and color stability. Translucency and optical characteristics significantly affect the aesthetics of ceramic restorations. The introduction of new virgilite crystals to novel ceramic advanced lithium disilicate through a matrix firing process enhances the material's strength and aesthetic quality according to the manufacturer. Four types of CAD/CAM ceramics; lithium disilicate (LD), leucite reinforced (LR), advanced lithium disilicate (ALD), and zirconia-reinforced lithium silicate (ZLS) exposed to different staining solutions (tea, cola, coffee, and distilled water). Each ceramic type had 120 specimens, divided into subgroups based on thickness (0.5 mm, 1 mm, and 1.5 mm). Color changes (ΔE00) and translucency parameters (TP00) were measured after thermocycling, and spectrophotometry was employed to evaluate ΔE00 and TP00 after 1, 7, and 30 days of exposure to the staining solutions. ZLS exhibited the lowest color stability, while lithium LD and ALD displayed the highest. Thickness significantly affected color stability, with 0.5 mm thickness showing the least change. The duration of exposure also impacted color changes, with 30 days causing the most significant shift. LD demonstrated the highest translucency. Coffee and tea induced more pronounced reductions in translucency and color stability compared to the control group. Material structure, thickness, staining solution, and exposure duration significantly influenced the color stability and translucency of CAD/CAM ceramics, with LD and ALD demonstrating superior color stability and LD exhibiting the highest translucency. [ABSTRACT FROM AUTHOR]

Purpose: To compare the clinical effectiveness of three different devices used in guided bone regeneration procedures for partially atrophic arches. Materials and methods: A randomised controlled trial with three parallel arms was conducted. The study evaluated titanium-reinforced polytetrafluoroethylene membrane (PTFE group), semiocclusive CAD/CAM titanium mesh (mesh group) and occlusive CAD/CAM titanium foil (foil group) in terms of surgical outcomes and complications as well as surgical times and surgeon satisfaction in 27 guided bone regeneration procedures, presenting results from 1 year post-implant placement. Results: Complications occurred in seven patients. No significant difference was found between the groups in terms of the occurrence of complications (P = 0.51), device exposure (P = 0.12) and implant failure (P = 0.650). Surgeon satisfaction varied significantly, with the PTFE group differing from the mesh (P = 0.003) and foil groups (P < 0.001), but not between meshes and foils (P = 0.172). Surgical times also differed significantly, with longer times for PTFE membranes compared to meshes (P < 0.001) and foils (P = 0.006), but with no difference between meshes and foils (P = 0.308). The mean reconstructed bone volume was 1269.55 ± 561.08 mm3, with no significant difference observed between the three groups (P = 0.815). There was also no significant difference for mean maximum height (6.72 mm, P = 0.867) and width (7.69 mm, P = 0.998). The mean marginal bone loss at 1 year after implant placement was 0.59 ± 0.27 mm. Conclusions: Although this study provides valuable insights into the potential benefits of using different types of CAD/CAM devices, further research with larger sample sizes and longer follow-up periods is warranted to validate these findings. [ABSTRACT FROM AUTHOR]

Artificial intelligence (AI) is increasingly prevalent in biomedical and industrial development, capturing the interest of dental professionals and patients. Its potential to improve the accuracy and speed of dental procedures is set to revolutionize dental care. The use of AI in computer-aided design/computer-aided manufacturing (CAD/CAM) within the restorative dental and material science fields offers numerous benefits, providing a new dimension to these practices. This study aims to provide a concise overview of the implementation of AI-powered technologies in CAD/CAM restorative dental procedures and materials. A comprehensive literature search was conducted using keywords from 2000 to 2023 to obtain pertinent information. This method was implemented to guarantee a thorough investigation of the subject matter. Keywords included; "Artificial Intelligence", "Machine Learning", "Neural Networks", "Virtual Reality", "Digital Dentistry", "CAD/CAM", and "Restorative Dentistry". Artificial intelligence in digital restorative dentistry has proven to be highly beneficial in various dental CAD/CAM applications. It helps in automating and incorporating esthetic factors, occlusal schemes, and previous practitioners' CAD choices in fabricating dental restorations. AI can also predict the debonding risk of CAD/CAM restorations and the compositional effects on the mechanical properties of its materials. Continuous enhancements are being made to overcome its limitations and open new possibilities for future developments in this field. [ABSTRACT FROM AUTHOR]

There is limited information on the repairability of prostheses produced with digital technology. This study aims to evaluate various surface treatments on flexural bond strength of repaired dentured base resins produced by digital and conventional methods. A total of 360 samples were prepared from one heat-polymerized, one CAD/CAM milled and one 3D printed denture base materials. All of the test samples were subjected to thermocycling (5–55 °C, 5000 cycles) before and after repair with auto-polymerizing acrylic resin. The test samples were divided into five subgroups according to the surface treatment: grinding with silicon carbide (SC), sandblasting with Al2O3 (SB), Er:YAG laser (L), plasma (P) and negative control (NC) group (no treatment). In addition, the positive control (PC) group consisted of intact samples for the flexural strength test. Surface roughness measurements were performed with a profilometer. After repairing the test samples, a universal test device determined the flexural strength values. Both the surface topography and the fractured surfaces of samples were examined by SEM analysis. The elemental composition of the tested samples was analyzed by EDS. Kruskal–Wallis and Mann–Whitney U tests were performed for statistical analysis of data. SB and L surface treatments statistically significantly increased the surface roughness values of all three materials compared to NC subgroups (p < 0.001). The flexural strength values of the PC groups in all three test materials were significantly higher than those of the other groups (p < 0.001). The repair flexural strength values were statistically different between the SC–SB, L–SB, and NC–SB subgroups for the CAD/CAM groups, and the L–SC and L–NC subgroups for the 3D groups (p < 0.001). The surface treatments applied to the CAD/CAM and heat-polymerized groups did not result in a statistically significant difference in the repair flexural strength values compared to the NC groups (p > 0.05). Laser surface treatment has been the most powerful repair method for 3D printing technique. Surface treatments led to similar repair flexural strengths to untreated groups for CAD/CAM milled and heat-polymerized test samples. [ABSTRACT FROM AUTHOR]

The study proposes strategies for conducting cutter-workpiece engagement (CWE) analysis and representation based on 4-dimensional (4D) geometric models. To achieve the CWE condition, two 4D models representing the workpiece and the machinable volume of the tool are introduced for Boolean subtraction and CWE calculation. However, performing set operations and mesh transformations on high-accuracy 4D mesh models can be complex and time-consuming. Therefore, a simplified CWE analysis process between the time-invariant workpiece-occupied region (WOR) and the tool-occupied region (TOR) has been implemented to illustrate the validity of the set operation algorithm. The results demonstrate the effectiveness of the proposed 4D Set operation algorithm and its application in CWE analysis to a certain extent. [ABSTRACT FROM AUTHOR]

Purpose: To evaluate, in vitro, the efficiency of a novel apparatus to test the adherence and penetration of bacteria on different membranes for guided regeneration. Methodology: To create the 3D device, Computer Aided Design/Computer Aided Manufacturing (CAD/CAM) systems were used. Three types of biomaterials were tested (n = 6): (DT) a collagen membrane; (DS) a polymer membrane; and (LP) a dense polytetrafluoroethylene barrier. The biomaterials were adapted to the apparatuses and challenged with two different monospecies bacterial culture of A. actinomycetemcomitans b and S. mutans. After 2 h, bacterial adherence and penetration were quantified by counting the number of colony-forming units (CFUs). Two specimens from each group were used for image analysis using Confocal Laser Scanning Microscopy. Statistical analysis was performed. Findings: The DS group had a higher adherence of S. mutans compared to A. actinomycetemcomitans b (p = 0.05). There was less adherence of A. actinomycetemcomitans b in the DS group, compared to the LP (p = 0.011) and DT (p < 0.001) groups. Only the membranes allowed penetration, which was blocked by barriers. The DT group allowed a greater penetration of S. mutans to occur compared to A. actinomycetemcomitans b (p = 0.009), which showed a higher penetration into the DS membranes compared to S. mutans (p = 0.016). The penetration of A. actinomycetemcomitans b through DS was higher compared to its penetration through DT and LP (p < 0.01 for both). DT and DS allowed a greater penetration of S. mutans to occur compared to LP, which prevented both bacterial species from penetrating. Conclusion: The apparatus allowed for the settlement and complete sealing of the biomaterials, enabling standardization. [ABSTRACT FROM AUTHOR]

Background: Due to rapid changes in dental practice, digital technologies have become prominent in undergraduate dental education at German universities in recent years. This shift has prompted a re-evaluation of content as well as teaching methods, particularly in courses where students are prepared for patient treatment. Traditional training on standardized models with resin teeth cannot cover the complexity of individual dental arch configuration encountered in patient situations. This study explores the use of 3D printing technology to create individualized models for prosthetic treatment simulations, aiming to evaluate students' feedback towards their experience with this training setting. Methods: First, the study describes the design and fabrication of individualized models with exchangeable teeth based on intraoral scans, mounted on connected plates with distance holders that can be fixed to standard phantom heads. Second, students provided feedback through a questionnaire, assessing various aspects such as the effectiveness of the 3D-printed models compared to traditional frasaco models for preparation exercises. Results: The results indicated that the design of the realized models was feasible for preparation training (question no. 4: 93% positive rating) and showed positive perceptions of the 3D-printed models, with students finding them effective for preparation exercises and beneficial in bridging the gap between simulation and real patient situations (question no. 6: 69% positive rating). Conclusions: The study suggests that 3D printing technology offers a valuable tool in dental education, providing realistic and patient-specific scenarios for students to enhance their skills and readiness for clinical practice. Further improvements in material properties in hand with cost-effective approaches are essential for widespread implementation. [ABSTRACT FROM AUTHOR]

Fracture resistance is an important parameter used to predict the performance of indirect dental restorations. The purpose of this in vitro study was to assess the fracture load of posterior milled nanoceramic crowns, in comparison with the lithium disilicate crowns, after fatigue loading, for two different restoration occlusal thicknesses. Forty test metal dies were fabricated by duplicating a master metal model consisting of an anatomic abutment preparation of the maxillary first premolar for a single crown. The dies were divided into two groups of 20 each for the fabrication of nanoceramic (Lava Ultimate) and lithium disilicate (IPS e.max CAD) single crowns. Each material group was further divided into two sub-groups of 10 dies each, based on crown occlusal thickness, of 0.5-mm and 0.75-mm (n = 10). Dental Type V stone dies poured from polyvinyl siloxane impressions of the test metal dies were laboratory scanned in order to design and mill 40 ceramic crowns. The crowns were cemented on to the test metal dies with a self-adhesive resin luting cement. All crowns were thermocycled (2500 cycles) and mechanically loaded (250,000 cycles) in a chewing simulator followed by static loading until failure, and the values noted. The data were statistically analyzed by 2-way ANOVA and Tukey HSD post-hoc multiple comparison tests (α = 0.05). The mean fracture loads ranged from 1022 to 1322 N for nanoceramic crowns and from 1145 to 1441 N for the lithium disilicate crowns. Two-way ANOVA revealed insignificant differences between the nanoceramic and lithium disilicate crowns (p > 0.05) in terms of fracture load. Significant differences were noted in the fracture resistance of crowns based on occlusal thickness (303 N; p = 0.013) regardless of the material used. Multiple comparisons by Tukey HSD post-hoc test showed insignificant differences between the four material-occlusal thickness groups (p > 0.05). The nanoceramic crowns were found to be comparable with lithium disilicate crowns in terms of fracture load. The mean fracture loads of all of the tested crowns were within the normal physiological masticatory load limits. Based on the fracture-resistance results, nanoceramic crowns seem to be suitable for clinical use for the tested occlusal thicknesses. [ABSTRACT FROM AUTHOR]

Background.: The present study assessed the impact of thermomechanical aging on the marginal fit of hybrid ceramic, reinforced composite resin, and lithium disilicate ceramic. Methods.: Eighteen human upper first premolars freshly extracted for orthodontic purposes were used to fabricate 18 CAD-CAM veneers and divided into three groups based on materials used: group H (n=6): hybrid ceramics (Vita Enamic), group R (n=6): reinforced composite resin (Brilliant crios), and group L (n=6): lithium disilicate ceramic (IPS e-max CAD). Each material's cementation procedure was carried out according to the manufacturer's instructions. The vertical marginal gap between the laminate veneer margin and the prepared tooth finish line was measured to assess the specimens by digital microscopy. Subsequently, all the samples were thermomechanically cycled (TMC) (5 °C to 55 °C, 30 seconds, 75000 cycles). Then, the vertical marginal gap was re-evaluated. Results.: The Brilliant crios group displayed a significantly lower vertical marginal gap mean score (31.36±2.82 µm) followed by Vita Enamic (39.27±6.54 µm) and E max (41.39±3.97 µm) groups. Similarly, after thermomechanical aging, the Brilliant crios group displayed a significantly lower vertical marginal gap mean score (41.83±8.28 µm) followed by Vita Enamic (55.47±18.65 µm), and the E max group showed the greatest vertical marginal gap mean score (59.43±16.27 µm). Conclusion.: Thermomechanical aging affected the marginal fit of different materials employed in the current research, and these changes were under the established clinical limit. [ABSTRACT FROM AUTHOR]

Although advancements in CAD/CAM technology allow for more personalized treatments, it is not clear how modifications in the CAD/CAM milling process could affect the restoration surface conditions and their mechanical behavior. The objective of this study was to evaluate the effect of different CAD/CAM milling protocols on the topography and fracture behavior of zirconia monolithic crowns (3Y-PSZ) subjected to a chewing simulation. Monolithic 3Y-PSZ premolar crowns were milled using three protocols (n = 13) (slow (S), normal (N), and fast (F)). Crowns were cemented on a dentin analog abutment and subjected to mechanical aging (200 N, 2 Hz, 1,500,000 cycles, 37 °C water). Surviving crowns were subjected to compressive load test and analyzed using fractography. Fracture load data were analyzed with two-parameter Weibull analysis. The surface topography of the crowns was examined with a stereomicroscope and a 3D non-contact profiler. All crowns survived the chewing simulation. Crowns milled using the F protocol had the greatest characteristic fracture load, while crowns produced with the S protocol showed high Weibull modulus. Groups N and S had a more uniform surface and detailed occlusal anatomy than group F. The CAD/CAM milling protocol affected the topography and mechanical behavior of 3Y-PSZ monolithic crowns. [ABSTRACT FROM AUTHOR]

Aim: The influence of different heat treatments on the mechanical properties of CAD/CAM ceramics was assessed. Methodology: A systematic search in five databases and gray literature was performed. In vitro studies providing data about the influence of various thermal treatments on the mechanical properties of CAD/CAM ceramics were included. Results: Out of 6500 articles found, 15 were included for results analysis. In the disilicate group, e.max CAD showed the best results in flexural strength (FS) and Vita Suprinity in microhardness (MH) and fracture toughness (FT). In the zirconium oxide group, Incoris exhibited better performance in FS while Razor Zirconia demonstrated superior MH and FT. Eleven studies had low and four had a moderate risk of bias (RoB). Conclusions: Both reinforced vitreous ceramics and zirconia ceramics, when subjected to high temperatures for short periods of time, significantly improve their mechanical properties. Favoring the biomechanical behavior of restorations present in the oral cavity, they are always subjected to constant changes in temperature, forces of different nature, intensity, or direction, changes in acidity, presence of moisture, etc., which make this a difficult environment for their clinical survival. [ABSTRACT FROM AUTHOR]

The latest generation of intraoral scanners can record the prosthetic field with relative ease, high accuracy and comfort for the patient, and have enabled fully digital protocols for designing and manufacturing complete dentures. The present study aims to examine the intaglio surface trueness of 3D printed maxillary dentures produced by fully digital workflow in comparison with dentures produced by analogue clinical and laboratory prosthetic workflow. The edentulous maxillary arch of 15 patients was scanned with an intraoral scanner as well as the intaglio of the delivered conventional denture. The scan of the edentulous arch was imported into a dental design software to produce the denture base which was then 3D printed. The intaglio surface of the finished 3D printed denture bases was digitized and used to assess the trueness of the printed denture bases compared to the intaglio surface of the conventional dentures as well as performing a trueness comparison in relation to the scanned edentulous arches. The dataset (n = 30) was subjected to Kruskal-Wallis test analysis, the significance level being established at α = 0.05. The results of the study showed that the printed group displayed better trueness values with a median of 176.9 μm while the analogue group showed a median of 342 μm. Employing a fully digital workflow to produce 3D-printed denture bases yields a consistent and precise manufacturing method when accounting for the intaglio surface of the denture. [ABSTRACT FROM AUTHOR]

An increasing number of CAD/CAM (computer-aided design/computer-aided manufacturing) hybrid materials have been introduced to the dental market in recent years. In addition, CAD/CAM hybrid materials for additive manufacturing (AM) are becoming more attractive in digital dentistry. Studies on material microstructures using micro-computed tomography (µ-CT) combined with scanning electron microscopy (SEM) have only been available to a limited extent so far. One CAD/CAM three-dimensional- (3D-) printable hybrid material (VarseoSmile Crown plus) and two CAD/CAM millable hybrid materials (Vita Enamic; Voco Grandio), as well as one direct composite material (Ceram.x duo), were included in the present study. Cylindrical samples with a diameter of 2 mm were produced from each material and investigated by means of synchrotron radiation µ-CT at a voxel size of 0.65 µm. Different samples from the same materials, obtained by cutting and polishing, were investigated by SEM. The 3D-printed hybrid material showed some agglomerations and a more irregular distribution of fillers, as well as a visible layered macrostructure and a few spherical pores due to the printing process. The CAD/CAM millable hybrid materials revealed a more homogenous distribution of ceramic particles. The direct composite material showed multiple air bubbles and microstructural irregularities based on manual processing. The µ-CT and SEM analysis of the materials revealed different microstructures even though they belong to the same class of materials. It could be shown that µ-CT and SEM imaging are valuable tools to understand microstructure and related mechanical properties of materials. • µ-CT and SEM imaging are valuable tools to understand material microstructure. • Mechanical properties might be derivable from the microstructure of the material. • Deviations from a homogeneous microstructure may influence material properties. [ABSTRACT FROM AUTHOR]

Background: This pilot study aimed to evaluate the effectiveness of digitally crafted customized healing abutments in stabilizing peri-implant soft tissues following tooth extraction and assess the preservation of peri-implant soft tissue architecture over 5 years. Material and Methods: Forty patients (age ≥ 25 years) were divided into test (n = 20) and control (n = 20) groups. The test group received dental implants with immediate loading after tooth extraction, along with customized healing abutments fabricated using CAD/CAM technology. The control group received dental implants with immediate loading without customized healing abutments. The primary outcome was the change in distance between the peri-implant soft tissue margin and implant fixture surface from baseline to 5 years post implantation. Results: In the test group, there was a significant decrease in the distance between the peri-implant soft tissue margin and fixture surface from baseline to 5 years (p < 0.001), with pairwise comparisons showing significant differences between multiple time points (p < 0.05). The control group showed less pronounced changes over time. Conclusions: Within the limitations of this pilot study, digitally fabricated customized healing abutments appear effective in stabilizing peri-implant soft tissues and preserving soft tissue architecture around dental implants over 5 years following immediate implant placement. Randomized controlled trials are needed to confirm these findings. [ABSTRACT FROM AUTHOR]

Considering the rapid evolution of lithium silicate-based glass ceramics (LSCs) in dentistry, this review paper aims to present an updated overview of the recently introduced commercial novel LSCs. The clinical and in vitro English-language literature relating to the microstructure, manufacturing, strengthening, properties, surface treatments and clinical performance of LSC materials was obtained through an electronic search. Findings from relevant articles were extracted and summarised for this manuscript. There is considerable evidence supporting the mechanical and aesthetic competency of LSC variants, namely zirconia-reinforced lithium silicates and lithium–aluminium disilicates. Nonetheless, the literature assessing the biocompatibility and cytotoxicity of novel LSCs is scarce. An exploration of the chemical, mechanical and chemo-mechanical intaglio surface treatments—alternative to hydrofluoric acid etching—revealed promising adhesion performance for acid neutralisation and plasma treatment. The subtractive manufacturing methods of partially crystallised and fully crystallised LSC blocks and the additive manufacturing modalities pertaining to the fabrication of LSC dental restorations are addressed, wherein that challenges that could be encountered upon implementing novel additive manufacturing approaches using LSC print materials are highlighted. Furthermore, the short-term clinical performance of zirconia-reinforced lithium silicates and lithium–aluminium disilicates is demonstrated to be comparable to that of lithium disilicate ceramics and reveals promising potential for their long-term clinical performance. [ABSTRACT FROM AUTHOR]

The widespread application of CAD/CAM technology in contemporary dentistry led to the development of promising restorative materials, such as resin composite blocks (RCBs). Thus, the present study aims to evaluate the mechanical properties of RCBs, comparing this material to the direct composite resin from the same manufacturer. Samples retrieved from three CAD/CAM resin composite blocks (Tetric CAD (TC), Ivoclar Vivadent, Grandio blocs (GB), VOCO GmbH and Brilliant Crios (BC), Coltene/Whaledent) and four direct composite resins (Tetric EvoCeram (TEC), Ivoclar Vivadent, GrandioSO (GS), VOCO GmbH, Brilliant EverGlow Translucent (BET) and Universal Shade (BEU), Coltene/Whaledent) were submitted to three-point bending flexural test and Vickers microhardness test. The resulting data of the flexural strength were analyzed using one-way ANOVA considering Bonferroni correction for post hoc tests (α = 0.05). The flexural modulus and Vickers microhardness results were analyzed using Welch's ANOVA considering Games–Howell correction for post hoc tests (α = 0.05). Regarding results, flexural strength and flexural modulus values ranged from 81.1 MPa (BEU) to 246.5 MPa (GB) and 10.6 GPa (BEU) to 20.3 GPa (GB), respectively. GS (121.2) and GB (136.2) groups were associated with the highest microhardness values. According to the post hoc tests, statistically significant differences in flexure strength were found in RCBs (BC, GB, and TC) compared to all direct composite resins. Flexural modulus and Vickers microhardness of RCBs (BC, GB, TC) were also significantly different from the direct composite resin (BET, BED, and TEC), except when comparing GS and GB for microhardness. In conclusion, differences between RCBs and direct composite resins were observed regarding flexural strength, flexural modulus, and microhardness, revealing that RCBs have enhanced mechanical properties compared to direct composite resins. [ABSTRACT FROM AUTHOR]

Copyright of Quintessenz der Zahntechnik is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Quintessenz der Zahntechnik is the property of Quintessenz Verlags GmbH and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Osteosarcomas arising within the pterygomaxillary/infratemporal fossa region are rare among the pediatric population. Survival rates are most influenced by tumor resection with negative margins, which can be dependent on surgical accessibility of the tumor site. The pterygomaxillary/infratemporal fossa location poses several challenges to safe and adequate tumor resection, including proximity of the facial nerve and great vessels and scarring associated with traditional transfacial approaches. In this article, we present the case of a 6-year-old boy with an osteosarcoma of the left pterygomaxillary/infratemporal fossa region successfully managed with an "oncoplastic" approach, incorporating the use of CAD/CAM and mixed reality technologies. [ABSTRACT FROM AUTHOR]

IntroductionThe aim of this study was to evaluate the fit performance of implant infrastructures manufactured by five different techniques: heat-press (IPS), milling (ZIR), lost wax (CER), calcinable cylinder (CAL), and CAD/Waxx® (CAD).MethodsThe methodology was based on the Replica Technique, which can simulate and evaluate the fit of the infrastructure on the implant component. Thus, each infrastructure was internally filled with low-viscosity silicone addition and seated on the component until its final setting, obtaining the replica of the cementation space. After removing the coping containing the silicone film, light-density silicone was inserted addition in place of the components, and in its surroundings, condensation silicone was applied, establishing support for the assembly. The joint was sectioned mesiodistally, photographed, and analyzed in image processing software in order to measure the thickness of the interface infrastructure/implant at five different areas: marginal opening (M), gingival-axial angle (G-A), axial region (A), axial-occlusal angle (A-O) and occlusal surface (O).ResultsThe lowest and the highest average thickness between groups was, respectively, IPS: 187.5 μm and CAD: 221.6 μm, with statistically significant differences (p

To evaluate the marginal accuracy of soft-milled cobalt-chromium (Co-Cr) compared to other construction methods/restorative materials in tooth/implant-supported restorations. Materials and Methods: PICO questions were defined, and a systematic search was conducted in six electronic databases. Titles and abstracts were collected and screened by two independent reviewers. After removing duplicate articles, the full texts of relevant articles were gathered, and the required information and data were extracted. Risk of bias was assessed and meta-analyses of the collected data were conducted using STATA software version 16. Results: A total of 1,914 experimental and clinical articles were reviewed, and 18 studies were selected for qualitative analysis. The 16 studies that were included in the meta-analysis showed no significant marginal gap differences between soft-milled Co-Cr and the following methods/materials: hardmilled Co-Cr (I2 = 92.9%, P = .86), casting wax (I2 = 90.9%, P = .42), laser-sintered Co-Cr (I2 = 93.3%, P = .46), and zirconia (I2 = 0.00%, P = .47). However, a significantly higher marginal accuracy of soft-milled Co-Cr was observed when compared to milled-wax casting (I2 = 93.1%, P < .001). Conclusion: The marginal gap of soft-milled Co-Cr restorations is within the acceptable clinical range and provides an accuracy similar to other available methods/materials for both the prepared implant abutment and tooth. [ABSTRACT FROM AUTHOR]

Purpose: To assess the mechanical performance and enamel-crack propensity of large MOD composite-resin restorations on maxillary molars with severely undermined cusps. Materials and Methods: Thirty-six extracted maxillary third molars (n = 12) received a standardized slot-type MOD preparation (5-mm depth by 5-mm bucco-palatal width) with severe undercuts, leaving unsupported buccal and lingual enamel cusps. A short-fiber reinforced composite resin base (SFRC, everX Flow, GC) was used for both the experimental direct approach and semi-direct CAD/CAM inlays (Cerasmart 270, GC). In the control group using a direct approach, Gradia Direct (GC) composite resin was used alone without SFRC. Optibond FL (Kerr) adhesive was used in all three groups (also for the immediate dentin sealing of inlays). Artificial masticatory forces were simulated under water using closed-loop servo-hydraulics (MTS Acumen 3). Each specimen was mounted at a 30-degree angle and positioned so that a cylindrical antagonistic cusp (actuator) contacted the internal palatal cusp slope of the restoration. Cyclic loading was applied at a frequency of 5 Hz, starting with a load of 200 N, increasing by 100 N every 2000 cycles. Samples were loaded until fracture and the number of endured cycles and failure modes of each specimen was recorded. Each sample was also evaluated for crack propensity during the experiment and for final failure mode (reparable failures above the CEJ [cementoenamel junction] vs irreparable failures below the CEJ). Results: Shrinkage-induced cracks (>3 mm) were found in most specimens for both direct groups (66% to 83%) but not with inlays. The survival of inlays with a SFRC base was superior to that of the direct SFRC restorations and Gradia Direct (control) restorations (Kaplan-Meier survival analysis and post-hoc log-rank test p < 0.000). The direct control group without SFRC exhibited not only the poorest survival but also 100% catastrophic failure (vs 42% and 17% for SFRC direct and SFRC inlays, respectively). Conclusion: Large MOD restorations with severely undermined cusps were most favorably restored with an SFRC base and a CAD/CAM inlay, yielding the highest survival rate, more reparable failures and absence of shrinkage-induced cracks. When a low-cost restoration must be chosen, the SFRC base will significantly improve the performance and failure mode of directly layered restorations. [ABSTRACT FROM AUTHOR]

Purpose: This study investigated the effect of different surface treatments and the effect of silane heat treatment with laser on the shear bond strength (SBS) of a nanoceramic composite to repaired hybrid CAD/CAM blocks. Materials and Methods: 60 hybrid CAD/CAM specimens (Cerasmart, GC) were prepared and randomly divided into six groups according to the different surface treatments (n = 10): group ER: Er:YAG laser+silane (Monobond Plus, Ivoclar Vivadent); group ER+SHT: Er:YAG laser+silane heat treatment; group B: bur+silane; group B+SHT: bur+silane heat treatment; group HF: hydrofluoric acid+silane; group HF+SHT: hydrofluoric acid+silane heat treatment. Afterwards, a universal adhesive (Universal Bond Quick, Kuraray) was applied, and nanoceramic resin composite (Zenit, President) cylinders were bonded to the Cerasmart specimens. They were thermocycled for 10,000 cycles (5-55°C) and subjected to SBS testing using a universal testing machine. Failure modes were examined with a stereomicroscope (15X). Scanning electron microscopy (SEM) was used to evaluate the surface topography (n = 2). The data were statistically analyzed using the Mann-Whitney U-test and the Kruskal-Wallis test (p < 0.05). Results: Regarding the surface treatments, group ER showed significantly lower SBS than groups B and HF (p < 0.05). Regarding the presence of silane heat treatment by laser, groups ER+SHT and B+SHT showed significantly lower SBS than group HF+SHT(p < 0.05). In addition, group B+SHT showed significantly lower SBS than did group B (p < 0.05). Conclusion: Er:YAG laser treatment for repairing hybrid CAD/CAM blocks was not as effective as bur roughening or hydrofluoric acid etching. Silane heated by Er:YAG laser was incapable of significantly increasing the bond strength to repaired hybrid CAD/CAM blocks. [ABSTRACT FROM AUTHOR]

The widespread application of CAD/CAM technology in contemporary dentistry led to the development of promising restorative materials, such as resin composite blocks (RCBs). Thus, the present study aims to evaluate the mechanical properties of RCBs, comparing this material to the direct composite resin from the same manufacturer. Samples retrieved from three CAD/CAM resin composite blocks (Tetric CAD (TC), Ivoclar Vivadent, Grandio blocs (GB), VOCO GmbH and Brilliant Crios (BC), Coltene/Whaledent) and four direct composite resins (Tetric EvoCeram (TEC), Ivoclar Vivadent, GrandioSO (GS), VOCO GmbH, Brilliant EverGlow Translucent (BET) and Universal Shade (BEU), Coltene/Whaledent) were submitted to three-point bending flexural test and Vickers microhardness test. The resulting data of the flexural strength were analyzed using one-way ANOVA considering Bonferroni correction for post hoc tests (α = 0.05). The flexural modulus and Vickers microhardness results were analyzed using Welch’s ANOVA considering Games–Howell correction for post hoc tests (α = 0.05). Regarding results, flexural strength and flexural modulus values ranged from 81.1 MPa (BEU) to 246.5 MPa (GB) and 10.6 GPa (BEU) to 20.3 GPa (GB), respectively. GS (121.2) and GB (136.2) groups were associated with the highest microhardness values. According to the post hoc tests, statistically significant differences in flexure strength were found in RCBs (BC, GB, and TC) compared to all direct composite resins. Flexural modulus and Vickers microhardness of RCBs (BC, GB, TC) were also significantly different from the direct composite resin (BET, BED, and TEC), except when comparing GS and GB for microhardness. In conclusion, differences between RCBs and direct composite resins were observed regarding flexural strength, flexural modulus, and microhardness, revealing that RCBs have enhanced mechanical properties compared to direct composite resins.

Considering the rapid evolution of lithium silicate-based glass ceramics (LSCs) in dentistry, this review paper aims to present an updated overview of the recently introduced commercial novel LSCs. The clinical and in vitro English-language literature relating to the microstructure, manufacturing, strengthening, properties, surface treatments and clinical performance of LSC materials was obtained through an electronic search. Findings from relevant articles were extracted and summarised for this manuscript. There is considerable evidence supporting the mechanical and aesthetic competency of LSC variants, namely zirconia-reinforced lithium silicates and lithium–aluminium disilicates. Nonetheless, the literature assessing the biocompatibility and cytotoxicity of novel LSCs is scarce. An exploration of the chemical, mechanical and chemo-mechanical intaglio surface treatments—alternative to hydrofluoric acid etching—revealed promising adhesion performance for acid neutralisation and plasma treatment. The subtractive manufacturing methods of partially crystallised and fully crystallised LSC blocks and the additive manufacturing modalities pertaining to the fabrication of LSC dental restorations are addressed, wherein that challenges that could be encountered upon implementing novel additive manufacturing approaches using LSC print materials are highlighted. Furthermore, the short-term clinical performance of zirconia-reinforced lithium silicates and lithium–aluminium disilicates is demonstrated to be comparable to that of lithium disilicate ceramics and reveals promising potential for their long-term clinical performance.

Abstract Background Complete tooth loss is a significant global oral health issue, particularly impacting older individuals with lower socioeconomic status. Computer-assisted technologies enhance oral healthcare access by the elderly. Despite promising in vitro reports on digital denture materials, evidence from randomized clinical trials (RCTs) is lacking to verify their performance. This cross-over RCT will investigate whether 3D-printed implant-retained mandibular overdentures (IMO) are more satisfactory for edentulous seniors than those made through traditional methods. Methods/design We will recruit 26 completely edentulous participants (any sex/gender) based on the following eligibility criteria: age ≥ 60 years, no tooth extraction in the past 12 months, two implants in the lower jaw, and need for new dentures in both jaws. Each participant will receive two denture pairs, either manufactured by 3D printing or traditionally, to be worn in a random order. A timeline of 3 months with each denture pair will be considered for outcome assessment (total: 6 months). Patient satisfaction with dentures will be measured by the McGill Denture Satisfaction Questionnaire. We will evaluate other patient-reported outcomes (including oral health-related quality of life) as well as clinician-assessed quality and cost. At the end of the trial, participants will choose which denture pair they wish to keep and interviewed about their experiences with the 3D-printed IMO. The quantitative and qualitative data will be incorporated through an explanatory mixed-methods strategy. A final quantitative assessment will happen after 12 months with the preferred IMO to assess the long-term performance and maintenance needs. Discussion This mixed-methods RCT will explore patient experiences with 3D-printed IMOs, aiming to assess the potential for altering clinical practice and dental public health policies. Our results will inform policies by showing whether 3D printing offers comparable outcomes at lower costs, facilitating greater access to oral care for the elderly. Trial registration ClinicalTrials.gov, NCT06155630, Registered on 04 December 2023. https://classic.clinicaltrials.gov/ct2/show/NCT06155630

Background/purpose: Nowadays, zirconia-based framework has been used for longspan or full-arch fixed dental prostheses (FDPs). This study aimed to evaluate the effect of pontic distribution on marginal and internal gaps of five-unit anterior zirconiabased DPs. Materials and methods: Right maxillary central incisor and second premolar were selected as terminal abutments and three different edentulous conditions with one nonterminal abutment were simulated. Marginal and internal gaps in each zirconia-based samples(n = 10) were examined by computer-aided replica technique. Five regions, including marginal gaps at mesial or distal finishing line, internal gaps at the mesial or distal axial wall, and occlusal surface, were statistically analyzed (α = .05). Results: Most of marginal gaps and internal gaps at axial wall were clinically acceptable, but larger at occlusal surface. For the three experimental groups, clinically accepted percentage with qualified gaps were less than 30%.There were statistical differences at axial wall over pontic side and marginal gaps over non-pontic side between groups (P

The introduction of CAD/CAM technology in dentistry opened the way for the use of numerous materials for prosthetic restorations: dental alloys, ceramic masses, zirconia, PMMA, etc. One of the materials suitable for CAD/CAM technology is zirconia, used either ceramic-plated or full-contour, through its mechanical and optical properties. Zirconia, proves to be a real competitor for dental alloys used in porcelain fused to metal technology, with great results on posterior and frontal areas of dental arches. Prosthetic restorations made of zirconia in transit areas (including canines and premolars) exemplify the perfect combination between mechanical resistance and aesthetics of this material.

Abstract Background The selection of post-core material holds significant importance in endodontically treated teeth, influencing stress distribution in the dental structure after restoration. The use of computer-aided design/computer-aided manufacturing (CAD/CAM) glass fiber post-core possesses a better adaptation for different root canal morphologies, but whether this results in a more favorable stress distribution has not been clearly established. Materials and methods This study employed finite element analysis to establish three models of post-core crown restoration with normal, oversized, and dumbbell-shaped root canals. The three models were restored using three different materials: CAD/CAM glass fiber post-core (CGF), prefabricated glass fiber post and resin core (PGF), and cobalt-chromium integrated metal post-core (Co-Cr), followed by zirconia crown restoration. A static load was applied and the maximum equivalent von Mises stress, maximum principal stress, stress distribution plots, and the peak of maximum displacement were calculated for dentin, post-core, crown, and the cement acting as the interface between the post-core and the dentin. Results In dentin of three different root canal morphology, it was observed that PGF exhibited the lowest von Mises stresses, while Co-Cr exhibited the highest ones under a static load. CGF showed similar stress distribution to that of Co-Cr, but the stresses were more homogeneous and concentrated apically. In oversized and dumbbell-shaped root canal remnants, the equivalent von Mises stress in the cement layer using CGF was significantly lower than that of PGF. Conclusions In oversized root canals and dumbbell-shaped root canals, CGF has shown good performance for restoration of endodontically treated teeth. Clinical relevance This study provides a theoretical basis for clinicians to select post-core materials for residual roots with different root canal morphologies and should help to reduce the occurrence of complications such as root fracture and post-core debonding.

Purpose: To evaluate the fracture load of monolithic, single-tooth implant-supported crowns cemented on solid or Ti-base (Variobase C) abutments. Materials and Methods: Besides abutment types (solid and Ti-base abutments), two ceramic systems (IPS e.max CAD and Zirconia inCoris ZI) and two occlusal thicknesses (0.5 and 1.5 mm) were also investigated in this study. In total, eight groups (n = 8) with 64 maxillary second premolar crowns were fabricated. All the crowns were cemented with resin cement, and the screw accesses in Ti-base groups were sealed with composite resin. After mechanical cycling, the specimens were submitted to fracture load test with the maximum force recorded in Newtons (N). Three-way analysis of variance (ANOVA) and Tukey post hoc test were used for statistical analyses (α = .05). Results: Both the abutment type (P = .0001) and the ceramic system (P = .0001) significantly affected the results. Screw-access channels reduced the fracture load of crowns by half compared to those cemented on solid abutments. The 1.5-mm and 0.5-mm zirconia crowns placed on solid abutments had similar highest fracture loads, while the e.max CAD groups positioned on Ti-base abutments showed significantly lower values compared with other groups. Conclusion: The screw access reduces the resistance of crowns supported by Ti-base abutments compared to crowns cemented on solid abutments. The inCoris ZI showed a higher fracture load than the IPS e.max CAD regardless of the abutment type and thickness. [ABSTRACT FROM AUTHOR]

The purpose of this study was to examine the biocompatibility of 3D printed materials used for additive manufacturing of rigid and flexible oral devices. Oral splints were produced and finished from six printable resins (pairs of rigid/flexible materials: KeySplint Hard [KR], KeySplint Soft [KF], V-Print Splint [VR], V-Print Splint Comfort [VF], NextDent Ortho Rigid [NR], NextDent Ortho Flex [NF]), and two types of PMMA blocks for subtractive manufacturing (Tizian Blank PMMA [TR], Tizian Flex Splint Comfort [TF]) as controls. The specimens were eluted in a cell culture medium for 7d. Human gingival fibroblasts (hGF-1) and human oral mucosal keratinocytes (hOK) were exposed to the eluates for 24 h. Cell viability, glutathione levels, apoptosis, necrosis, the cellular inflammatory response (IL-6 and PGE2 secretion), and cell morphology were assessed. All eluates led to a slight reduction of hGF-1 viability and intracellular glutathione levels. The strongest cytotoxic response of hGF-1 was observed with KF, NF, and NR eluates (p < 0.05 compared to unexposed cells). Viability, caspase-3/7 activity, necrosis levels, and IL-6/PGE2 secretion of hOK were barely affected by the materials. All materials showed an overall acceptable biocompatibility. hOK appeared to be more resilient to noxious agents than hGF-1 in vitro. There is insufficient evidence to generalize that flexible materials are more cytotoxic than rigid materials. From a biological point of view, 3D printing seems to be a viable alternative to milling for producing oral devices. [ABSTRACT FROM AUTHOR]

Immediate dentin sealing (IDS) is a method of improving the bond strength of indirect dental restorative materials to dentin and belongs to the biomimetic protocols of contemporary dentistry. The purpose of this systematic review was to evaluate the effect of IDS on the bond strength of resin-based CAD/CAM materials to dentin. PubMed and MEDLINE, Scopus, and the Web of Science were searched by two individual researchers, namely for studies that have been published in English between 1 January 2005 and 31 December 2023 in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) statement. The inclusion criteria encompassed articles related to in vitro studies, measuring the bond strength through microtensile bond strength (μ-TBS), micro-shear bond strength (μ-SBS), tensile bond strength (TBS) or shear bond strength (SBS) tests after the use of the IDS technique. The included restorative materials comprised resin-based CAD/CAM materials bonded to dentin. A total of 1821 studies were identified, of which 7 met the inclusion criteria. A meta-analysis was not deemed appropriate due to the high level of diversity inthe publications and techniques. The use of IDS yielded higher bond strength outcomesin various experimental conditions and resin-based CAD/CAM materials. Overall, IDS in CAD/CAM restorations may contribute to better clinical outcomesand improved restoration longevity due to this property. [ABSTRACT FROM AUTHOR]

Aim of this prospective study was to assess full mouth rehabilitation of severe tooth wear patients using minimally invasive CAD/CAM resin-based composite (RBC) restorations and direct veneers by evaluating restoration survival up to 5.5-years. Twenty-two patients with generalized severe tooth wear with functional and/or esthetic problems were included. Following minimally invasive preparation, CAD/CAM RBC restorations (LAVA Ultimate,3M) were adhesively luted, direct RBC veneers (Filtek Supreme XTE, 3M) were applied in the aesthetic region. Patients were recalled after 1m,1y,3y,5y and seen in between recalls by their general dentists or at the clinical study center if complaints occurred. Failures were categorized as F1 (severe deficiencies requiring replacement/extraction), F2 (localized deficiencies requiring re-cementation/repair) and F3 (small chippings requiring refurbishment/monitoring). Survival of indirect restorations was evaluated using lifetables and Kaplan-Meier-graphs, distinguishing between failure categories and tooth type (front teeth=FT, premolars=PM, molars=M). F1 + F2 and F1 + F2 + F3 failures were analyzed using Cox regression on the variables tooth type/ location, age, gender and VDO increase (p < 0.05). 568 indirect restorations and 200 direct veneers in 21 patients evaluated for up to 5.5-years. For indirect restorations, 96 failures were recorded (F1:6;F2:41;F3:49) and annual failure rates were 0.29%(FT), 1.56%(PM), 2.93%(M) for F1 +F2 and 0.53%(FT), 2.42%(PM), 6.11%(M) for F1 + F2 + F3. Reasons for failure were chipping fracture (48), adhesive fracture (32), complete debonding (7), caries (4), endodontic treatment (1) and reasons unknown (documentation general dentists, 4). Molar tooth type had a statistically significantly increased probability of failure compared with front teeth and premolars for F1 + F2 + F3 (p < 0.006). Direct veneer restorations showed 18 failures (F1:2;F2:9;F3:7). Minimally invasive CAD/CAM RBC restorations combined with direct RBC veneers showed an acceptable clinical mid-term survival for restorative rehabilitation of severely worn dentitions. • Minimal-invasive CAD/CAM RBC restorations can protect severely worn dentitions. • Restorations on molars exhibited higher failure probability than those on other tooth types. • Refurbishment and repair of RBC restorations should be considered before replacement. [ABSTRACT FROM AUTHOR]