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A triple-armed, double-blind randomized controlled trial with cross-over design investigated patient-reported satisfaction and objective dental evaluation of a 3-unit, monolithic zirconium dioxide (ZrO2), implant-supported fixed dental prosthesis (iFDP) fabricated with 2 completely digital workflows and 1 mixed analog-digital workflow. Participants enrolled required rehabilitation of 2 dental implants in posterior region of either of the arches with a 3-unit, ZrO2 iFDP. A total of 20 participants received the 3 types of ZrO2, iFDP fabricated by 3 different methods. Thus, a total of 60 iFDPs were fabricated in the study. 20 iFDP were fabricated by complete digital workflow by using 3Shape Trios 3 Intraoral scanner (IOS) and 3 Shape designing software (Test-1). In second group (Test-2) 20 iFDPs were fabricated by using Dental Wings Virtuo Vivo IOS and Dental Wings original software (DWOS) for CAD designing. 20 iFDPs (control) were fabricated by mixed analogue-digital workflow by using Polyether impression and Exocad Lab software. The primary clinical outcome was blinded, subjective evaluation on visual analogue scale (VAS) by the participant, and an objective evaluation on VAS by a dentist at the time of prosthetic try-in of each of the 3 types of prosthesis. Secondary outcome was patients' perception about the impression procedures in the 3 different workflows on VAS. The study was conducted at 2 instances during the prosthetic rehabilitation. The primary outcomes were assessed at the time of prosthetic try-in. The secondary outcome was observed after the impression session. Clinical parameters were measured on VAS from 0 to 100 score. For the primary outcome, VAS score was recorded for each iFDP as observed for patient perception (satisfaction) and dentist evaluation (objective). The perception about impression was also recorded on VAS. Descriptive analysis of all scores was done by mean and standard deviation. ANOVA test was used for comparisons among the 3 different types of iFDP. Tukey's HSD was used for pairwise comparisons within ANOVA. Linear regression analyses was done to compare overall satisfaction of the patients and the dentist within each group. The level of significance was set at α = 0.05. After the start of recruitment in January 2020, there were no losses and exclusions. VAS for patient satisfaction was higher than VAS for dentist evaluation. Patient satisfaction among Test-1, Test-2, and Control showed no significant difference (P = 0.876). Dentist satisfaction among workflows were also not significantly different (P = 0.22). The relationship between VAS scores of patients and dentists was weak for Test-1 (R-value = -0.424, P = 0.062), Test-2 (R-value = 0.116, P = 0.068), and Control (R-value = -0.183, P = 0.441). Significant differences for patients' perceptions related to the treatment time for impression procedure (P = 0.005), convenience of impression procedure (P < 0.001), bad oral taste with the impression procedure (P < 0.001), and nausea with the impression procedure (P < 0.001) were observed. Subjective patient satisfaction was similar when comparing iFDPs fabricated with 3 different workflows. Objective dentist evaluation was also similar when comparing the 3 types of iFDPs. However, patient satisfaction of the workflow was higher than dentist evaluation, although there was no correlation between the two. Lower VAS in dentist's evaluation has been attributed to strict standardized clinical criteria and critical expert view. The study also reveals that patients have a favorable perception and preference in favor of digital impressions as compared to use of elastomeric impression materials.

Key Points Demonstrates the difficulties of matching teeth and the need for an objective and reliable means of shade matching. Digital images acquired under standard lighting conditions can provide reliable colour measurements. The use of digital images in shade matching will allow technicians to view variations in tooth colour and improve communication between technicians and clinicians. Objective To develop a shade matching method based on digital imaging and to compare observers' ability using this method with the conventional one set against a spectrophotometric 'gold standard'. Methods Two Vita Lumin shade guides were used in this study, nine shades being selected from the first Vita Lumin shade guide, A2, A3, A3.5, B2, B3, B4, C1, C2 and C3. A second shade guide was used to match the selected shades. A Nikon Coolpix 990 digital camera with Nikon SB21B ring flash was used to record the digital images of the shade tabs of the two shade guides and the images were processed using Adobe Photoshop software. A total of 27 samples (three replicates of each shade of the nine tabs selected) were matched with a digital shade guide prepared from the digital images of the second shade guide by 10 observers on a computer screen (computerised matching method). The 10 observers also matched the same shade tabs using the conventional matching method simulated in a phantom head. In addition, colour values were obtained from the digital images using Adobe Photoshop and quantified according to an internationally recognised scale as CIELAB colour values, L * ,a * ,b * . The relationship of the digitally derived CIELAB values to the CIELAB values obtained using a reflectance spectrophotometer was investigated. Results The cross tabulation statistical analysis showed a statistically significant difference (p<0.001) between the conventional method and the computer method with a 43% and 61.1% correct match respectively. There was also a statistically significant difference between observers in both methods (p<0.001 and p<0.04 for the conventional and computer methods respectively). A statistically significant high correlation of the CIELAB colour values were found between both colour measurement methods (p<0.001). Conclusion The observers' shade matching performance was significantly better with the computer method compared with the conventional one. There was a large variation in the observers' matching ability. The digital camera can be used as a means of colour measurements in the dental clinic.

Key Points Discusses the latest technologies in 3D imaging and printing that can be applied in dentistry. Suggests these technologies could be used in daily practice. 3D printing has been hailed as a disruptive technology which will change manufacturing. Used in aerospace, defence, art and design, 3D printing is becoming a subject of great interest in surgery. The technology has a particular resonance with dentistry, and with advances in 3D imaging and modelling technologies such as cone beam computed tomography and intraoral scanning, and with the relatively long history of the use of CAD CAM technologies in dentistry, it will become of increasing importance. Uses of 3D printing include the production of drill guides for dental implants, the production of physical models for prosthodontics, orthodontics and surgery, the manufacture of dental, craniomaxillofacial and orthopaedic implants, and the fabrication of copings and frameworks for implant and dental restorations. This paper reviews the types of 3D printing technologies available and their various applications in dentistry and in maxillofacial surgery.

Background The continuous development in dental processing ensures new opportunities in the field of fixed prosthodontics in a complete virtual environment without any physical model situations. The aim was to compare fully digitalized workflows to conventional and/or mixed analog-digital workflows for the treatment with tooth-borne or implant-supported fixed reconstructions. Methods A PICO strategy was executed using an electronic (MEDLINE, EMBASE, Google Scholar) plus manual search up to 2016–09-16 focusing on RCTs investigating complete digital workflows in fixed prosthodontics with regard to economics or esthetics or patient-centered outcomes with or without follow-up or survival/success rate analysis as well as complication assessment of at least 1 year under function. The search strategy was assembled from MeSH-Terms and unspecific free-text words: {((“Dental Prosthesis” [MeSH]) OR (“Crowns” [MeSH]) OR (“Dental Prosthesis, Implant-Supported” [MeSH])) OR ((crown) OR (fixed dental prosthesis) OR (fixed reconstruction) OR (dental bridge) OR (implant crown) OR (implant prosthesis) OR (implant restoration) OR (implant reconstruction))} AND {(“Computer-Aided Design” [MeSH]) OR ((digital workflow) OR (digital technology) OR (computerized dentistry) OR (intraoral scan) OR (digital impression) OR (scanbody) OR (virtual design) OR (digital design) OR (cad/cam) OR (rapid prototyping) OR (monolithic) OR (full-contour))} AND {(“Dental Technology” [MeSH) OR ((conventional workflow) OR (lost-wax-technique) OR (porcelain-fused-to-metal) OR (PFM) OR (implant impression) OR (hand-layering) OR (veneering) OR (framework))} AND {((“Study, Feasibility” [MeSH]) OR (“Survival” [MeSH]) OR (“Success” [MeSH]) OR (“Economics” [MeSH]) OR (“Costs, Cost Analysis” [MeSH]) OR (“Esthetics, Dental” [MeSH]) OR (“Patient Satisfaction” [MeSH])) OR ((feasibility) OR (efficiency) OR (patient-centered outcome))}. Assessment of risk of bias in selected studies was done at a ‘trial level’ including random sequence generation, allocation concealment, blinding, completeness of outcome data, selective reporting, and other bias using the Cochrane Collaboration tool. A judgment of risk of bias was assigned if one or more key domains had a high or unclear risk of bias. An official registration of the systematic review was not performed. Results The systematic search identified 67 titles, 32 abstracts thereof were screened, and subsequently, three full-texts included for data extraction. Analysed RCTs were heterogeneous without follow-up. One study demonstrated that fully digitally produced dental crowns revealed the feasibility of the process itself; however, the marginal precision was lower for lithium disilicate (LS2) restorations (113.8 μm) compared to conventional metal-ceramic (92.4 μm) and zirconium dioxide (ZrO2) crowns (68.5 μm) ( p  < 0.05). Another study showed that leucite-reinforced glass ceramic crowns were esthetically favoured by the patients (8/2 crowns) and clinicians (7/3 crowns) ( p  < 0.05). The third study investigated implant crowns. The complete digital workflow was more than twofold faster (75.3 min) in comparison to the mixed analog-digital workflow (156.6 min) (p < 0.05). No RCTs could be found investigating multi-unit fixed dental prostheses (FDP). Conclusions The number of RCTs testing complete digital workflows in fixed prosthodontics is low. Scientifically proven recommendations for clinical routine cannot be given at this time. Research with high-quality trials seems to be slower than the industrial progress of available digital applications. Future research with well-designed RCTs including follow-up observation is compellingly necessary in the field of complete digital processing.

The purpose of this study was to assess the effect of 3D printing technology (SLA vs. DLP), print orientation (0°, 10°, 20°), and model shell thickness (2 mm vs. 4 mm) on the manufacturing accuracy of full-arch dental casts with teeth preparations. A reference STL file of a maxillary arch, featuring preparations for a posterior crown and a three-unit bridge, was used to fabricate 144 printed models (72 with SLA and 72 with DLP). Each technology group was subdivided based on print orientation (0°, 10°, 20°) and shell thickness (2 mm, 4 mm), resulting in 12 subgroups with n = 12 each. All models were scanned and analyzed for global and landmark-level deviations using surface superimposition (Geomagic Control X). Trueness was calculated via root mean square (RMS) error, and precision was determined as standard deviation (SD). Data were statistically analyzed using the Kruskal–Wallis test to assess trueness, and precision was evaluated using Levene’s median-based test (α = 0.05). Printing technology (DLP vs. SLA), model orientation, and shell thickness showed no significant impact on the overall accuracy, as measured by trueness (RMS: p  = 0.453–1.000) and precision (SD: p  = 0.117). The overall trueness (RMS) values ranged from 73.9 to 194 µm, with all groups remaining below the clinical acceptability threshold (< 0.2 mm). Isolated significant differences were observed at specific anatomical points but did not impact overall model performance. The type of printing technology, orientation angle, and shell thickness did not significantly affect the global accuracy of full-arch models for fixed prosthodontics.

Background In recent years, artificial intelligence (AI) has made remarkable advancements and achieved significant accomplishments across the entire field of dentistry. Notably, efforts to apply AI in prosthodontics are continually progressing. This scoping review aims to present the applications and performance of AI in dental crown prostheses and related topics. Methods We conducted a literature search of PubMed, Scopus, Web of Science, Google Scholar, and IEEE Xplore databases from January 2010 to January 2024. The included articles addressed the application of AI in various aspects of dental crown treatment, including fabrication, assessment, and prognosis. Results The initial electronic literature search yielded 393 records, which were reduced to 315 after eliminating duplicate references. The application of inclusion criteria led to analysis of 12 eligible publications in the qualitative review. The AI-based applications included in this review were related to detection of dental crown finish line, evaluation of AI-based color matching, evaluation of crown preparation, evaluation of dental crown designed by AI, identification of a dental crown in an intraoral photo, and prediction of debonding probability. Conclusions AI has the potential to increase efficiency in processes such as fabricating and evaluating dental crowns, with a high level of accuracy reported in most of the analyzed studies. However, a significant number of studies focused on designing crowns using AI-based software, and these studies had a small number of patients and did not always present their algorithms. Standardized protocols for reporting and evaluating AI studies are needed to increase the evidence and effectiveness.

Introduction A little over ten years ago, zirconia crowns made their debut in the field of dentistry. Despite early problems with the chipping of veneering porcelain, clinical studies have demonstrated excellent performance. It is essential for a ceramic crown to have good aesthetic qualities, in addition to having good mechanical characteristics. The exceptional mechanical qualities of zirconia crowns and the simplicity with which they may be machined, employing computer-aided design and computer-aided manufacturing schemes, are primarily responsible for the widespread use of these materials in clinical settings. New ceramic-based materials, including monolithic zirconia, zirconia-containing lithium disilicate ceramics, and graded glass/zirconia/glass, have recently been launched in the field of dentistry. These newly discovered zirconia crown materials stem from varied technological approaches, each likely to lead to additional clinical advancements. At this point, it seems imperative to offer a concentrated report on the newer developments, along with essential clinical recommendations for best clinical outcomes with zirconia crowns. Types of studies This review article is a consolidation of several case studies, cohort studies and systematic reviews, as well as experimental and observational randomised control trials and other peer-reviewed articles. Results On reviewing, a concise list of clinical recommendations is generated, demonstrating that monolithic zirconia offers some clinical advantages over veneered zirconia crowns. Conclusion This review article discloses various clinical revelations and in-office recommendations for favourable usage of zirconia ceramic crowns that can lead to better patient outcomes and long-term clinical success rates. Key points To master clinical knowledge with novel insights on zirconia crowns. To grasp current trends and methodology for long-term clinical success with zirconia ceramics. To gain scientific expertise through clinical guidelines for long-standing restorative success. To learn new innovations and trends with zirconia crowns and restorations.

The aim of this study was to compare the compressive strength, microstructural characteristics, and cost-effectiveness of cast dental posts fabricated using two techniques: torch casting (TC) and electric arc casting (EAC), both integral to the lost wax method. Employing an applied research approach with an experimental design, the study analyzed 40 non-precious gold (NPG) alloy cast posts, divided equally into two groups of 20 for each technique. The selection process was non-probabilistic and based on convenience, with specific inclusion and exclusion criteria to ensure precision and relevance. The results reveal a significant advantage for the EAC technique. In Essay 1, EAC posts exhibited a mean compressive strength of 206.102 MPa, compared to 157.207 MPa for TC posts. Similarly, in Essay 2, EAC posts showed a mean strength of 172.625 MPa versus 136.303 MPa for TC posts. These differences were statistically significant (p < 0.05), with EAC posts also displaying smaller failure diameters and areas, suggesting better load distribution. Morphological and microstructural analysis using scanning electron microscopy (SEM) revealed a porous surface with irregular topography in both techniques. However, EAC samples displayed crystalline growths within the copper matrix, indicating a non-homogeneous stoichiometry, while TC samples showed aluminum-enriched zones, suggesting a non-uniform elemental distribution. Chemical composition analysis via energy-dispersive spectroscopy (EDS) identified copper (Cu) as the predominant element in both samples, with trace elements such as aluminum (Al), nickel (Ni), and iron (Fe) also present. X-ray diffraction (XRD) analysis further revealed distinct crystalline phases, with EAC samples exhibiting a higher proportion of Cu₃Zn and gamma-Fe phases compared to TC samples. A cost analysis using Python 3.13 and Monte Carlo simulation with 1,000 iterations revealed that EAC is more expensive, with a total cost per unit of 2.181compared to 1.467 for TC, primarily due to higher operational costs. The Mann-Whitney U test confirmed significant differences in cost distributions (p < 0.001), indicating that EAC has higher and more variable costs. In conclusion, the study demonstrates that EAC produces dental models with significantly higher compressive strength and a more refined microstructure compared to TC, enhancing restoration durability. However, its higher operational costs must be considered. These findings provide valuable information for dental professionals, particularly in low- to middle-income countries, and suggest that future research should explore additional properties such as corrosion resistance and biocompatibility to further validate the clinical applicability of these materials.

Key Points In general a significant decrease in marginal accuracy should be taken into consideration for partial coverage restorations after adhesive cementation. Adhesive luted partial coverage restorations appear to have a moderate increase in marginal gap width under masticatory ageing. The introduced new preparation designs fulfil the technical demands to fabricate accurate fitting all ceramic partial coverage restorations. Objectives To determine the influence of the preparation design and the dimensions of all-ceramic partial coverage restorations (PCR) on the marginal accuracy before and after masticatory simulation. Methods In this in vitro study 80 extracted human maxillary molars were restored with MOD inlay restorations and four different modified PCR restorations using a new press ceramic IPS e.max® Press (IPS e.max® Press VP 1989). The teeth were divided into five groups of 16 specimens each and prepared as follows: Group A received an MOD inlay preparation and Group B, C, D and E received modified PCR. The restorations were adhesively luted and exposed to a mastication simulator. The discrepancies of the marginal fit were examined on epoxy replicas before and after luting as well as after masticatory simulation at 200× magnification. Results The mean (geometrical) [95% confidence limits] marginal gap decreased from Group A to E before cementation (A-83[77-90]μm, B-68[65-70]μm, C-59[55-64]μm, D-56[52-61]μm, E-50[45-55]μm). Group A had significantly higher marginal gap values than group B (p = 0.017) and the other groups (p<0.0001). After cementation the marginal accuracy was recorded as following: A-103[93-114]μm, B-101[94-108]μm, C-93[89-98]μm, D-102[98-105]μm and E-99[96-102]μm. Cementation increased the marginal gap in groups B-E significantly (p<0.00001), not significantly in group A (p = 0.059). Artificial ageing (A-116[106-127]μm, B-114[109-120]μm, C-106[103-110]μm, D-109[100-118]μm and E-109[105-112]μm) led to further significant decrease of marginal accuracy in Group B (p = 0.029) and C (p = 0.026) only. After cementation and masticatory simulation of the ceramic restorations, the marginal gap values of Groups A, B, C, D and E did not significantly differ from each other (p = 1.00). Conclusions The result of this in vitro study showed that IPS e.max® Press can be used to fabricate all-ceramic inlays and PCR which meet the requirements in terms of a clinically acceptable marginal gap, irrespective of the preparation design used. However, the preparation design and dimensions of the restorations appeared to affect the initial marginal fit and flowing off of luting material during the cementation process. The factors responsible for these findings require further substantiation.

Purpose The purpose of this systematic review was to explore and identify the factors that influence the accuracy of intraoral scanning in implant dentistry, with a specific focus on scan bodies (ISBs). Methods Following the PRISMA 2020 guidelines, this study conducted a thorough electronic search across MedLine, PubMed, and Scopus to identify relevant studies. Articles were screened based on titles, abstracts, and full texts for relevance. The Robins I tool assessed the risk of bias in various study types. Data extraction occurred based on predetermined parameters for studying specimens and assessing outcomes. Results 16 studies met the specified criteria and were consequently included in the systematic review. Due to variations in variables and methods across the selected studies, statistical comparison of results was not feasible. Therefore, a descriptive review approach was chosen, acknowledging the substantial heterogeneity in the reviewed literature. Conclusions The precision of virtual scan results is contingent upon diverse characteristics of ISBs and implants. These factors encompass their placement within the dental arch, structural design, shape, material composition, color, and the manufacturing system, all of which contribute to scan accuracy. Additionally, considerations such as the intraoral scanner (IOS) type, scanning technique, use of scan aids, inter-implant distance, scan span, and the number of implants warrant evaluation. In the context of capturing implant positions, intraoral scanning with ISBs demonstrates comparable accuracy to traditional impression methods, particularly in single and short-span scenarios. However, the existing data lacks sufficient information on in vivo applications to formulate clinical recommendations. Graphical abstract