O emprego da moldagem digital na prática odontológica - relato de caso / The use of digital molding in dental practice ­ case report

O avanço da tecnologia de digitalização de imagens e desenvolvimento de dispositivos de fresagem possibilitaram a otimização de diversos processos na Odontologia. O emprego do escaneamento intraoral e do sistema CAD-CAM (CAD - Computer Aided Design; CAM - Computer Aided Manufacturing) aprimorou a realização de reabilitações protéticas, permitindo a obtenção de peças de alta qualidade em tempo reduzido. O objetivo deste trabalho é relatar um caso de reabilitação de um incisivo central inferior a partir de escaneamento intraoral, com scanner Omnicam (DentsplySirona Charlotte, NC, EUA) e aplicação do sistema CAD-CAM.

The advancement of image digitization technology and the development of milling devices have made it possible to optimize various processes in Dentistry. The use of intraoral scanning and the CAD-CAM system (CAD - Computer Aided Design; CAM - Computer Aided Manufacturing) has improved the performance of prosthetic rehabilitations, allowing the obtaining of high quality parts in a reduced time. The objective of this work is to report a case of rehabilitation of a lower central incisor using intraoral scanning, with an Omnicam scanner (Dentsply Sirona) and application of the CAD-CAM system.

Fully digital versus conventional workflow: Are removable complete overdentures equally good? A randomized crossover trial.

INTRODUCTION: Implant-supported removable complete overdentures (IODs) are a common treatment in case of edentulism and malfunctioning of the conventional denture. Manufacturing IODs in a conventional way (C-IODs) is time-consuming, but in a digital workflow, this can be done in three sessions. Digitally produced IODs (3D-IODs) are also more advantageous than C-IODs because lost or broken 3D-IODs can be swiftly reproduced as the digital design is always available. PURPOSE: To prove in a non-inferiority study, with a margin of 0.3 point per Oral Health Impact Profile-20 (OHIP-20) question, that IODs made according to a fully digital workflow (3D-IODs), function as good as C-IODs with respect to patient-reported outcome measures (PROMs). MATERIALS AND METHODS: This randomized crossover study included 36 fully edentulous patients who showed extreme resorption of the maxillary alveolar process, making denture retention difficult. After a maxillary bone augmentation and the installation of 4-6 implants, each patient wore both types of IOD for 1 year each, with the order reversed in two subsets of patients. The 3D-IODs and C-IODs were fabricated in advance for both jaws (at least two mandibular implants were already present). The OHIP-20 survey was performed at baseline, after 1 year (before the IOD switch), and after 2 years to determine patient satisfaction scores using a visual analog scale (VAS). The general health status was assessed using the Short Form (SF-36) questionnaire. RESULTS: Regarding the PROMs, patients preferred the 3D-IOD: the improvement on the overall OHIP scale (0-4), expressed as a mean, was 0.26 points greater than for the C-IOD (p < 0.001). This applied also to the VAS scale (1-100) with an increase of 7.37 points (p < 0.001). Regarding the SF-36 scale, only for the item "emotional well-being," the 3D-IOD scored significantly better (p = 0.033). CONCLUSION: Compared with conventionally fabricated C-IODs, fully digitally produced 3D-IODs resulted in significantly higher OHIP-20 and satisfaction scores.

Effect of artificial aging and different surface finishing protocols on the flexural strength and surface hardness of a photopolymer for manufacturing monolithic polychromatic complete dentures using PolyJet 3D printing.

PURPOSE: This study evaluated the effect of thermocycling and three different surface finishing protocols on the flexural strength and surface hardness of a novel photopolymer intended for manufacturing monolithic polychromatic dental prostheses using PolyJet 3D printing. MATERIALS AND METHODS: A total of 90 specimens were manufactured using a photopolymer for 3D printing monolithic polychromatic dental prostheses using PolyJet technology (TrueDent; Stratasys USA). The specimens were divided into three groups (n = 30) according to the surface finishing protocol used: The control group Pumice+Moldent (Pumice), Pumice+Optiglaze (Optiglaze), and Polycril+Moldent (Polycril). Half of the specimens of each group (n = 15) were subjected to 5000 thermocycles (Thermocycling Unit OMC350TSX; Odeme Dental Research, Santa Catarina, Brazil), The other half was stored in distilled water at room temperature for 7 days before testing. The flexural strength of the specimens was assessed in a universal testing machine (MTS Sintech ReNew; MTS Systems Corp, Aiden Prairie, MN), and the Vicker's surface hardness was evaluated with a microhardness tester (Micro indentation Hardness Tester LM247AT; Leco Instruments Ltd, Ontario, Canada). The resulting data was analyzed using two-way ANOVA tests, and Fisher's protected least significant differences (α = 0.05) in a professional statistical analysis computer program (SAS v9.4, SAS Institute, Cary, NC) RESULTS: The two-way ANOVA tests suggested a statistically significant effect of thermocycling and the surface finishing protocol on the flexural strength (p = 0.01) but without significant interaction between both independent variables (p = 0.18). The post hoc analysis revealed no significant differences in the flexural strength between groups without thermocycling (p > 0.05). Thermocycling decreased the flexural strength of all groups (p < 0.05), and the Optiglaze group exhibited significantly higher flexural strength than the Polycril and Pumice groups after thermocycling (p < 0.01). Regarding the surface hardness, the two-way ANOVA indicated a significant 2-way interaction between thermocycling and the surface of the finishing protocol (p = 0.01). The post hoc analysis showed that the Optiglaze group had significantly higher hardness than the other groups, both before and after thermocycling (p < 0.01) After thermocycling, a significant decrease in surface hardness was observed in the Polycril and Pumice groups (p < 0.01). CONCLUSIONS: Surface finishing protocols and artificial aging can affect the surface hardness and flexural strength of the dental prostheses manufactured using the photopolymer studied. Careful polishing and surface finishing are required to ensure favorable clinical performance. Coating with a photopolymerizable glaze material seems to be a favorable surface treatment for monolithic polychromatic complete dentures fabricated using PolyJet 3D printing.

Repair of fractured metal-ceramic restoration using CAD/CAM technologies. Case report.

Fractures in esthetic ceramic veneering are one of the potential failure modes during prosthetic treatment. Depending on the type of chipping fracture, there are three possible outcomes: replacement, restoration repair, or polishing of the fractured area. Computer-aided design and manufacturing (CAD/CAM) technologies provide new methods to the maintenance and repair of fixed metal-ceramic restorations. Here, we report the case of a 68-year-old patient who came to the dentist with comcerns about his appearance due to spontaneous gingival bleeding and a fracture in the ceramic veneering of a metal-ceramic restoration. The patient reported occurrences of bruxism. The proposed treatment plan included consultation with a cardiologist, periodontal treatment, polishing of the chipped areas, repair of the fractured zone with an exposed metal core, and fabrication of a mouth guard. Once the ceramic veneering on the palatal and buccal sides of the retainers had been completely removed, a digital impression was obtained and sent to the dental lab so that milled zirconium veneer could be manufactured. The veneering was cemented the next day using the standard prosthetic field preparation process and resin-modified glass ionomer cement. In conclusion, fixed metal-ceramic restorations that have fractured can be successfully repaired using CAD/CAM methods and materials.

Wide Restorative Emergence Angle Increases Marginal Bone Loss and Impairs Integrity of the Junctional Epithelium of the Implant Supracrestal Complex: A Preclinical Study.

AIM: To assess the influence of the emergence angle on marginal bone loss (MBL) and supracrestal soft tissue around dental implants. MATERIALS AND METHODS: In six mongrel dogs, the mandibular premolars and molars were extracted. After 3 months of healing, four dental implants were placed in each hemimandible. The implants were randomly allocated to receive one of four customized healing abutments, each with a different value of the restorative emergence angle: 20°, 40°, 60° or 80°. Intra-oral radiographs were taken after placing the healing abutments and at 6, 9, 16 and 24 weeks of follow-up. Then, micro-CT and undecalcified histology and synchrotron were performed. MBL over time was analysed with generalized estimating equations (GEEs) and adjusted for baseline soft-tissue thickness. RESULTS: From implant placement to 24 weeks, GEE modelling showed that the MBL at mesial and distal sites consistently increased over time, indicating MBL in all groups (p < 0.001). The model indicated that MBL varied significantly across the different restorative angles (angle effect, p < 0.001), with 80° showing the greatest bone loss. Micro-CT, histology and synchrotron confirmed the corresponding trends and showed that wide restorative angles (60° and 80°) impaired the integrity of the junctional epithelium of the supracrestal tissue. CONCLUSIONS: A wide restorative angle increases MBL and impairs the integrity of the junctional epithelium of the implant supracrestal complex.

Coloring Multilayer Zirconia May Affect Its Optical and Mechanical Properties.

The coloring process of monolithic dental zirconia caused considerable debate on the possible effects of different coloring methods. The main objective of this study was to investigate the influence of pigments in 3 multilayer 5-mol% yttria partially stabilized zirconia (5Y-PSZ) disks (Lava Esthetic A2 [Zr-AGG_A2] and Bleach [Zr-AGG_BL], both 3M Oral Care, and Katana STML A2 [Zr-NoAGG], Kuraray Noritake). The influence of pigment addition on the translucency parameter (TP00), fracture toughness, Vickers hardness, biaxial strength, and hydrothermal stability was assessed and correlated with the microstructure and phase composition. The pigment composition and distribution were evaluated by light and fluorescence microscopy, electron probe microanalysis, and nano-scanning electron microscopy. The chemical and phase composition and aging behavior were assessed using X-ray fluorescence and X-ray diffraction, respectively, while the aging sensitivity of the pigments was evaluated using micro-Raman spectroscopy. In contrast to Zr-NoAGG, possessing a typical 5Y-PSZ microstructure, the pigment additions in both Zr-AGG_A2/BL zirconia resulted in large yellow and blue fluorescent Er-, Hf-, and Al-containing agglomerates composed of small grains (0.57 µm and 0.38 µm, respectively, vs. 0.92 µm for the surrounding grains) with lower Y2O3 content. Zr-AGG_A2 had the lowest aging resistance, with transformation degradation occurring exclusively within the pigment agglomerates. All zirconia grades had a high Y2O3 content (4.2%-5.7 mol%) tetragonal ZrO2 phase and a high (42%-55 wt%) cubic ZrO2 phase content. Although no statistical differences were measured for hardness and toughness, Zr-NoAGG had a significantly higher TP00, higher flexural strength, and lower mechanical reliability compared to both Zr-AGG_A2/BL zirconia. The rare-earth oxide-containing zirconia agglomerates that were added as pigments to the multilayered monolithic Zr-AGG_A2/BL zirconia are the cause for their lower optical and mechanical properties and reduced aging resistance.

The colour stability of 3D-printed, non-invasive restorations after 24 months in vivo - esthetically pleasing or not?

OBJECTIVES: The aim of the present prospective study was to evaluate the colour stability of 3D-printed non-invasive restorations after 24 months in vivo. METHODS: The study included 29 patients, who received 3D-printed restorations made of a computer-aided design (CAD) / computer aided-manufacturing (CAM) hybrid material (n = 354). Restoration colour of 190 restorations was measured using a spectrophotometer. By applying the CIELAB system, *L (lightness), a* (red-green) and b* (blue-yellow) values were recorded. An evaluation of the colour differences (ΔE) after 6, 12 and 24 months was conducted. RESULTS: Analysis of colour differences of 3D-printed restorations showed continuous discolouration of the restorations. After one year 34 % and after two years 18 % of the restorations were rated alpha or bravo, indicating no or hardly visible colour change. After two years, 54 % of the evaluated restorations yielded a colour difference with ΔE > 6.8 (delta). More than 82 % of the evaluated restorations showed values between ΔE 3.8 - 6.8 (charlie) and ΔE ˃ 6.8 (delta) after two years. CONCLUSIONS: 3D-printed non-invasive restorations showed an overall reduced colour stability after 24 months in vivo. CLINICAL SIGNIFICANCE: The present study provides first clinical data regarding 3D-printed restorations. These restorations are recommended for a wearing time of about 6 months.

Computer-Assisted Porcelain Laminate Veneer Preparation: A Scoping Review of Stereolithographic Template Design and Fabrication Workflows.

Computer-assisted preparation of porcelain laminate veneers (PLVs) using stereolithographic templates has been developed to enhance the accuracy of tooth preparation. However, the digital workflows involved in guided PLV preparation remain inconsistently defined across various practices. Therefore, this scoping review aimed to examine publications on computer-assisted PLV preparation to identify the key stage of digital workflows involved in designing and fabricating stereolithographic templates, as well as to highlight the limitations of various template designs. This scoping review aimed to identify publications on digital workflows for designing and fabricating stereolithographic templates in computer-assisted porcelain laminate veneer preparation. A systematic search on MEDLINE/PubMed, Web of Science and Scopus identified English-language articles published from 2014 to March 2024. Eligible articles focused on digitally designed and fabricated tooth reduction templates for porcelain laminate veneers, excluding conventional tooth preparation procedures for tooth reduction assessment. Seven clinical reports were included, demonstrating various 3D data acquisition techniques for virtual patient generation. All articles described virtual diagnostic wax-ups on digital casts, with two using a virtual articulator. Only five articles documented chair-side mock-ups with resin trial restorations to evaluate planned dental esthetics. Additionally, virtual tooth preparation prior to templates design was included in only four articles. The templates were designed using different software and ranged from simple designs with access windows to complex stacked templates with rotary instrument sleeved windows. Each template design had limitations affecting tooth reduction accuracy. All articles reported printing templates in clear acrylic resin using different technologies. In conclusion, the review highlights a lack of standardization in the digital workflow for designing stereolithographic templates for PLVs. Establishing a sound protocol for designing the tooth reduction templates is essential to ensure the accuracy and consistency of veneer preparation.

The Mechanical and Clinical Properties of Customized Orthodontic Bracket Systems-A Comprehensive Review.

The rise of computer-aided design and computer-aided manufacturing (CAD/CAM) and 3D printing technologies in orthodontics has revolutionized the development of customized labial and lingual bracket systems with a variety of materials, which offer potential advantages over traditional orthodontic brackets. To highlight the current state of knowledge regarding the mechanical and clinical properties of CAD/CAM and 3D-printed custom bracket systems, we conducted a comprehensive search across the PubMed, Embase, Cochrane Library, Web of Science, and Scopus databases to identify relevant articles published before April 2024. Mechanical (including fracture toughness, hardness, modulus of elasticity, frictional resistance, slot accuracy, torque transmission, and shear bond strength) and clinical (including treatment efficiency and duration, cost, and comfort) properties were compared between traditional and customized orthodontic bracket systems in the current review. Our findings suggest that customized brackets have the potential to increase bracket slot precision, reduce treatment time, and offer cost-efficiency. However, it is worth noting that the advantages and disadvantages of customized bracket systems vary depending on the bracket material and the manufacturing methods, warranting comprehensively controlled investigations in the future.

Evaluation of Wear on Primary Tooth Enamel and Fracture Resistance of Esthetic Pediatric Crowns Manufactured from Different Materials.

Background and Objectives: Advances in dental materials and CAD-CAM technology have expanded crown options in primary teeth due to their improved appearance and mechanical properties. Thus, this study aimed to assess the enamel wear and fracture resistance of prefabricated, milled, and 3D-printed esthetic pediatric crowns. Materials and Methods: The study involved 60 extracted maxillary second primary molars and 60 3D-printed resin dies, divided into six groups based on different crown materials (n = 10): prefabricated zirconia, prefabricated composite, milled composite, milled resin matrix ceramic, milled PEEK, and 3D-printed resin. Prefabricated crowns were selected after the preparation of the typodont mandibular second primary molar tooth, while milled and 3D-printed crowns were custom produced. The specimens underwent mechanical loading of 50 N at 1.6 Hz for 250,000 cycles with simultaneous thermal cycling. The 3D and 2D wear amounts were evaluated by scanning the specimens before and after aging. Then, the fracture resistance and failure types of the restorations were recorded. Results: The results showed that the milled PEEK group had superior fracture resistance compared to the other groups, while prefabricated zirconia crown group had the lowest value. Milled resin matrix ceramic crown group displayed the lowest 3D wear volume, while 3D-printed crown group showed the highest 2D wear. Conclusions: The restorative material type did not have a significant effect on the wear of primary tooth enamel. The fracture resistance of the tested materials differed according to the material type. Although the milled PEEK group showed the highest fracture resistance, all tested materials can withstand chewing forces in children.

Mechanical, Adhesive and Surface Properties of a Zirconia-Reinforced Lithium Silicate CAD/CAM Ceramic Exposed to Different Etching Protocols.

The aim of this investigation was to evaluate the effect of etching protocols on bond strength, surface roughness, and mechanical properties of a zirconia-reinforced lithium silicate (ZLS) CAD/CAM-ceramic. In total, 100 bars (ISO 6872), 75 plaques, and 25 cubes were cut from ZLS blocks(Vita Suprinity®). The surfaces were standardized, crystallized and divided into five groups: 1. control (no/treatment-C), 2. 5%-Hydrofluoric-acid (HF)/20 s (HF5%20s), 3.HF5%60s, 4.HF10%20s, and 5.HF10%60s. Flexural strength (FS) (three-point bending test, 1 mm/min), roughness (Pa), and micro-shear bond-strength (µSBS) tests were performed. The data were statistically analyzed with one-way ANOVA, Tukey's test (p ˂ 0.05) and Weibull (FS data). C showed higher Pa (1.176 ± 0.370 µm) than HF10%60s (0.627 ± 0.236 µm) and all other groups. Groups C and 20 s showed the most irregular surface patterns. The FS results were not influenced by etching protocols, while the Weibull modulus was, with the 5%HF groups being the most reliable (m: 5.63/6.70), while C and HF10%60s (m: 2.78/2.73) were the least reliable. All fractures originated from surface defects on the treated side of specimens. The 5%HF groups showed higher µSBS (20 s: 21.35 ± 4.70 MPa; 60 s: 23.50 ± 4.27 MPa) than the 10%HF groups (20 s: 14.51 ± 2.47 MPa; 60 s: 16.54 ± 3.12 MPa) and C (6.46 ± 2.71 MPa). The most prevalent failure pattern was "mixed" for etched groups, and "adhesive" for C. Etching protocols affect the evaluated properties by roughening materials' surface and, in some cases, regularizing surface defects. The best overall outcomes were achieved when applying 5%HF.

Bond strength of 4META-MMA-TBB resin to a CAD/CAM composite resin block and analysis of acetone-insoluble cured resin residues at adhesive interfaces.

This study investigated the adhesion of 4META-MMA-TBB resin to CAD/CAM composite resin blocks. CAD/CAM composite resin blocks were subjected to alumina blasting, ceramic primer treatment, or both, and then bonded with 4META-MMA-TBB resin. The tensile bond strength of 4META-MMA-TBB resin to blocks without surface treatment was approximately 20 MPa, but with surface treatment, it significantly improved to approximately 40 MPa. Cohesive failure was observed in some blocks with surface treatment with both alumina blasting and ceramic primer. As a result of Soxhlet extraction of the adhesive interface with acetone solvent and FT-IR spectrum analysis, it was found that PMMA remained on the block surface when surface treatment with both alumina blasting and ceramic primer were performed. These results demonstrated that the bond strength of 4META-MMA-TBB resin is significantly improved when both alumina blasting and ceramic primer are applied as surface pretreatment to the CAD/CAM composite resin block.

Evaluation of the accuracy of digital indirect bonding vs. conventional systems: a randomized clinical trial.

OBJECTIVES: To compare the accuracy and chair time of self-ligating brackets using direct bonding, traditional indirect bonding (IB), and computer-aided design/computer-aided manufacturing (CAD/CAM) IB techniques after orthodontic leveling and alignment. MATERIALS AND METHODS: Forty-five patients were randomly assigned to three bonding groups (G1 [n = 15], G2 [n = 15], and G3 [n = 15]). Evaluation after the alignment and leveling phases used two parameters of the objective grading system of the American Board of Orthodontics for root parallelism and posterior marginal ridges, assessed using panoramic radiographies (PR I and PR II), a digital model, and a plaster model. Blinding was only applied for outcome assessment. No serious harm was observed except for gingivitis associated with plaque accumulation. RESULTS: Although G3 showed better numerical results, they were not statistically significant in the radiographic or model evaluations (P > .001). Mean chair time was significantly shorter in G3 (1.1 ± 11.8 min) vs. G1 (56.7 ± 7.3 min) and G2 (52.8 ± 8.3 min; P < .001). CONCLUSIONS: The CAD/CAM IB system for self-ligating brackets was as effective as conventional methods, with a shorter chair time.

Effect of preparation design on fracture resistance of molars restored with occlusal veneers of different CAD-CAM materials: an in vitro study.

BACKGROUND: Occlusal veneer had been evaluated for mechanical properties using lithium disillicate. However, studies evaluating the mechanical properties of occlusal veneer with different preparation designs and ceramic materials are lacking. So, this in vitro study aimed to evaluate the fracture resistance of occlusal veneers with two designs fabricated from two different ceramic materials. MATERIAL AND METHODS: Fourty mandibular third molars were distributed to 2 groups (n = 20) according to preparation design: group (O) anatomical occlusal reduction and group (OA) anatomical occlusal and 1 mm axial reduction. Each group was additionally subdivided into two subgroups (n = 10) according to ceramic materials; in subgroup X, lithium disilicate (e.max CAD, Ivoclar AG, Schaan, Liechtenstein) was used, and in subgroup S, zirconia-reinforced lithium silicate (ZLS) (Vita Suprinity, VitaZahnfabrik, Bad Säckingen, Germany) was used. All specimens were cemented with a light-cure resin cement (Choice 2, Bisco, Schaumburg, USA). 5000 thermocycles were applied to all specimens with both temperatures of 5 °C and 55 °C in two water baths; the dwell time was 30s at each bath, and the transfer time was 10s. Then all specimens were subjected to a fatigue simulation under dynamic loading of 200 N for 250,000 cycles. A universal testing machine (5500R/1123, Instron, Norwood, USA) was used to evaluate the fracture strength with a crosshead speed of 1 mm/min. All data were analyzed statistically by using a two-way ANOVA, and for some violations of assumptions, these results were compared with those obtained by the nonparametric test (Scheirer Ray Hare) (α = 0.05). RESULTS: A statistically significantly higher fracture resistance in the 'OA' (3389 N) compared to the 'O' (2787 N) group regardless of the ceramic material (P < .001) and a statistically significantly higher fracture resistance in the 'X' (3295 N) compared to the 'S' (2881 N) regardless of the preparation design (P = .015). CONCLUSIONS: For occlusal veneers, all preparation designs and materials (such as Vita Suprinity and e.max CAD) had clinically acceptable fracture resistance values that were greater than the maximal biting forces. On the other hand, the e.max CAD with occlusal veneer, including axial reduction design, demonstrated the maximum fracture resistance value. Finally, no relationship between fracture strength and mode of failure was found.

Comparison of denture space and patient satisfaction for neutral zone versus standard-designed digital dentures restoring mandibular resorbed ridges: A crossover randomized clinical trial.

PURPOSE: To compare neutral-zone-designed and standard-designed digital complete dentures used to restore severely resorbed ridges through differential digital analysis of teeth arrangement position, shape of the polished surface, and assessment of patient satisfaction. MATERIALS AND METHODS: This study applied a within-subject comparison of two denture forms: computer-aided design and computer-aided manufacturing (CAD-CAM) dentures designed based on the bone-support concept (control group) and CAD-CAM dentures designed based on the neutral-zone concept (test group). Twelve completely edentulous patients exhibiting advanced ridge atrophy were recruited, and they were randomly assigned to use one of the two dentures before the other. A comparison between the two groups' virtual denture confines was conducted using "Medit compare" digital software. The average values of three-dimensional deviations between the two dentures at different regions were calculated. The "patient denture assessment" questionnaire was used to gauge participants' satisfaction with their dentures. The obtained scores were used to compare the two denture types. RESULTS: The position of the neutral zone was significantly shifted at the level of both denture teeth and denture base outer limits (p = 0.001). The greatest deviation was calculated at the region of the palatal polished surface followed by lingual flange contours, while the buccal flanges displayed the least deviations (p ≤ 0.05). Statistically significant differences were observed between patients' satisfaction with neutral zone and standard dentures regarding function and comfort, retention, and stability of lower dentures (p ≤ 0.05). CONCLUSION: CAD-CAM neutral-zone dentures have distinctly different anatomical confines that can be clinically correlated to their better impact on patient acceptance.

Influence of nanohydroxyapatite mouthwash on the growth of Candida albicans biofilm on milled denture surfaces: An in vitro study.

PURPOSE: There is a need for effective solutions for the persistent prevalence of denture stomatitis (DS) in denture-wearing populations. This study assessed the impact of nanohydroxyapatite (nanoHAP) nanoparticles on Candida albicans biofilm formation on milled polymethylmethacrylate (PMMA) denture bases. MATERIALS AND METHODS: Acquired salivary pellicle was formed on disks milled from a prepolymerized PMMA puck. The disks were assigned to two groups, A (n = 18) and B (n = 18), and each group was further subdivided into three subgroups (6/subgroup), each treated with either Polident solution (antibacterial denture cleanser), nanoHAP mouthwash, or distilled water. Disks in group A subgroups were soaked in their respective treatment solutions for 8 h, followed by biofilm formation on the disk for 24 h. Disks in group B subgroups had C. albicans biofilm formed on them for 24 h, followed by soaking in their respective treatment solutions for 8 h. Biofilm thickness, biomass, and live/dead cell ratio were determined using a confocal laser scanning microscope. Biofilm morphology was examined with a scanning electron microscope (SEM). Data were analyzed by ANOVA and Tukey-Kramer multiple comparisons (α = 0.05). RESULTS: In group A, nanoHAP mouthwash displayed significant anti-adhesive properties. In group B, biofilm biomass and thickness significantly decreased (p < 0.05), with the nanoHAP showing the most substantial reduction in existing biofilm compared to other solutions, but it did not significantly affect cell viability. CONCLUSIONS: This study demonstrated the efficacy of nanoHAP mouthwash in inhibiting C. albicans biofilm formation when used as a storage medium for acrylic dentures. It suggests its potential clinical application for preventing denture stomatitis in patients.

Comparison of Direct Intraoral Scan and Traditional Impression for CAD/CAM Mandibular Overdenture Base: RCT on Peri-implant Marginal Bone Changes.

AIM: This study aimed to evaluate the impact of digital vs traditional impression techniques on peri-implant vertical bone resorption in the creation of mandibular overdenture bases supported by four implants using CAD/CAM technology. MATERIALS AND METHODS: Twenty edentulous patients were placed in four mandibular implants and randomly divided into groups: (A) the control group (CIG) (n = 10); patients obtained CAD/CAM denture base using conventional impression technique and group (B) the study (DIG) group (n = 10); patients obtained CAD/CAM denture base using digital impression technique. Peri-implant vertical bone height was measured immediately (T0), 6 (T6), and 12 (T12) months after insertion. Peri-implant vertical bone loss (VBL) was calculated first 6 months (T1), the second 6 months (T2), and 1 year (T3) after insertion. RESULTS: For both groups, the survival rates of inserted implants were 100%. The amount of VBL in the first year in both groups was within normal ranges. In both groups, VBL significantly decreased over time. The control group recorded significantly higher VBL than (DIG) group at T2 (p = 0.006) and at T3 (p = 0.005). CONCLUSION: Digital intraoral scanning technique may be considered a more beneficial registration method than traditional impression technique for the construction of CAD/CAM 4-implant-assisted overdenture base regarding the preservation of vertical bone levels. CLINICAL SIGNIFICANCE: Both digital intraoral scanners and conventional impression techniques can be used for the construction of CAD/CAM-implant-assisted overdenture bases regarding the preservation of peri-implant vertical bone resorption. How to cite this article: Seifeldeen AR, Aboelez MA, Gebreel AA, et al. Comparison of Direct Intraoral Scan and Traditional Impression for CAD/CAM Mandibular Overdenture Base: RCT on Peri-implant Marginal Bone Changes. J Contemp Dent Pract 2024;25(6):527-534.

In-vitro comparison of fracture resistance of CAD/CAM porcelain restorations for endodontically treated molars.

BACKGROUND: This study evaluates the fracture strength and patterns of feldspathic porcelain restorations made using CAD/CAM technology for lower first molars with extensive crown destruction. The restorations include post-core and full-contour crown, composite resin core and full-contour crown, and endocrown. This research provides insights into effective restorative options to address tooth fracture risk, supporting minimally invasive procedures and CAD/CAM integration in dental practices. METHODS: This study utilized 80 permanent mandibular first molars, which were divided into four groups: Group I (Post-Core-Full-contour crown), Group II (Core- Full-contour crown), Group III (Endocrown), and Group IV (Control). Root canal treatment was performed on all samples except for the control group. Following access cavity preparation, restorations for each tooth were fabricated using the CAD/CAM system and cemented with resin cement. The specimens were embedded in acrylic blocks. After undergoing thermomechanical aging, the samples were subjected to fracture resistance testing using a universal testing machine, which applied force until fracture occurred. The fracture patterns were subsequently analyzed, and the data were statistically evaluated using the Kruskal-Wallis and Chi-Square tests (p < 0.05). RESULTS: A significant difference in fracture values under axial forces was observed (p < 0.05). The control group had the highest fracture strength (1830 ± 277 N), while the Core- full-contour crown group showed the lowest (1532 ± 371 N). Failure types varied significantly among the groups (χ2 = 26.886, df = 9, p = 0.001). The most common failure type was Type-2 (33.75%), characterized by restorable fractures, while Type-3 fractures, unrestorable, were the least common (12.5%). CONCLUSIONS: The findings underscore the significance of technological advancements in CAD/CAM for effectively restoring endodontically treated teeth with extensive crown damage. This study contributes valuable insights, emphasizing the clinical relevance of selecting appropriate restorative options to mitigate the risk of tooth fracture associated with coronal restoration failures.

Impact of liner treatment on the translucency of CAD/CAM multi-colored lithium disilicate and multi-layered zirconia implant-supported crowns, and evaluation of fracture strength of ceramic crowns.

This study aimed to evaluate the optical properties of liner-treated CAD/CAM Multi-colored lithium disilicate (Amber Mill Direct; AMD) and multi-layered zirconia (Omega multi; OM) implant-supported crowns, as well as their effect on the fracture strength of Ti or Zr abutments to which they were applied. After sintering AMD and OM ceramic blocks, they were classified into three groups: untreated, liner-treated, and liner-treated with added color. Optical properties were evaluated by analyzing color differences using background materials to assess translucency and the masking ability of liner-treated ceramics. Subsequently, the fracture strength of implant-supported crowns applied to Ti or Zr abutments was measured, and statistical analysis was conducted using Weibull statistics. Untreated AMD exhibited the highest translucency. Liner treatment reduced translucency in both ceramics, while color-added liner treatment increased translucency. Liner-treated AMD showed greater color difference compared to OM, whereas color-added liner treatment reduced the color difference. Fracture strength was highest in Ti abutment-OM crowns (548.03 N) and lowest in Zr abutment-AMD crowns (283.58 N). Additionally, the Weibull coefficient was over twice as high in Ti abutment-AMD crowns (m = 17.500). Color liners can adjust the high translucency of lithium disilicate ceramics to block discoloration, providing natural tooth-like color and enabling the creation of esthetic restorations. Furthermore, lithium disilicate ceramic crowns applied to Ti abutments exhibited high Weibull coefficients and fracture strengths.

Masking ability of CAD-CAM resin-matrix ceramics with different translucencies and thicknesses combined with four cement shades against varying background colors when facing veneer restorations.

BACKGROUND: To evaluate the comprehensive effect of translucency, thickness, cement shades, and background color on the masking ability of resin-matrix ceramic veneer restorations. METHODS: Resin-matrix ceramic specimens with 2 translucencies (LT, HT) and 3 thicknesses (0.5, 1.0, and 1.5 mm) were made of Upcera Hyramic (A2 shade). Cement specimens were made of Variolink N in 4 shades (yellow, white, transparent, and bleach XL). Five background specimens were made of IPS Natural Die Material in 5 shades (ND1, ND2, ND3, ND4, and ND5). Color coordinates of 120 subgroups (n = 5) of combined specimens composed of different ceramic, cement, and background specimens were obtained using a spectroradiometer. Color difference (ΔE00) compared with a 4-mm thick specimen of LT and HT ceramics was calculated and four-way ANOVA was used for statistical analysis (α = 0.05). RESULTS: Translucency, thickness, cement shade, background color, and their interaction had significant effects on ΔE00 (p < 0.001). ΔE00 values of HT groups were always higher than that of LT groups and were greater than 1.8 against all background colors. ΔE00 values of LT groups could be achieved to be less than 1.8 with appropriate thickness and cement shade. ΔE00 value decreased with increasing ceramic thickness. The effect of cement shade on ΔE00 had no obvious regularity, but ΔE00 values of bleach XL cement shade group were always lower than other cement shade groups under ND3 and ND5 background color. CONCLUSIONS: The masking ability of CAD-CAM resin-matrix ceramics can be simultaneously affected by translucency, thickness, cement shade, and background color. Resin-matrix ceramics with low translucency has a better masking ability than that with high translucency. The masking ability of CAD-CAM resin-matrix ceramics increase with increasing thickness. Cement shade has less impact on the final color of resin-matrix ceramic restorations.