A 48-month clinical performance of hybrid ceramic fragment restorations manufactured in CAD/CAM in non-carious cervical lesions: case report.

From the restorative perspective, various methods are available to prevent the progression of non-carious cervical lesions. Direct, semi-direct, and indirect composite resin techniques and indirect ceramic restorations are commonly recommended. In this context, semi-direct and indirect restoration approaches are increasingly favored, particularly as digital dentistry becomes more prevalent. To illustrate this, we present a case report demonstrating the efficacy of hybrid ceramic fragments fabricated using computer-aided design (CAD)/computer-aided manufacturing (CAM) technology and cemented with resin cement in treating non-carious cervical lesions over a 48-month follow-up period. A 24-year-old male patient sought treatment for aesthetic concerns and dentin hypersensitivity in the cervical region of the lower premolar teeth. Clinical examination confirmed the presence of two non-carious cervical lesions in the buccal region of teeth #44 and #45. The treatment plan involved indirect restoration using CAD/CAM-fabricated hybrid ceramic fragments as a restorative material. After 48 months, the hybrid ceramic material exhibited excellent adaptation and durability provided by the CAD/CAM system. This case underscores the effectiveness of hybrid ceramic fragments in restoring non-carious cervical lesions, highlighting their long-term stability and clinical success.

Reinforcement of 3D-printed resins for denture base by adding aramid fibers: Effect on mechanical, surface, and optical properties.

PURPOSE: The present study evaluated the mechanical, surface, and optical properties of 3D-printed resins for removable prostheses reinforced by the addition of aramid fibers. MATERIALS AND METHODS: According to ISO 20795-1:2013 standards, specimens were printed using a digital light processing 3D printer and divided into two groups (n = 06/group): 3D-printed resin for denture base as the control group, and a group with the same 3D-printed resin in addition of 5% aramid fibers as the experimental group. Red aramid fibers were chosen for aesthetic characterization. The specimens were evaluated for their mechanical properties, such as elastic modulus (GPa), flexural strength (MPa), and superficial properties by their surface microhardness (KHN), surface roughness (µm), and surface free energy (mJ/m2). Optical properties were evaluated by the color difference (∆E00) between groups. The statistical test chosen after the exploratory analysis of the data was One-way ANOVA followed by Tukey's HSD (α = 0.05). RESULTS: The results showed statistical differences in elastic modulus (p < 0.0001), flexural strength (p < 0.0001), surface free energy polar variable (p = 0.0322), total surface free energy (p = 0.0344), with higher values for the experimental. Surface hardness and surface roughness showed no statistical difference (p ≥ 0.05). The color difference (∆E00) obtained through the CIEDE2000 calculus was below the perceptibility threshold (≤1.1). CONCLUSION: Adding aramid fibers to 3D-printed resin for denture bases resulted in better mechanical properties, without major alterations in surface properties. In addition, it is an easy-to-apply choice for mechanical reinforcement and aesthetic characterization, with the expression of small blood vessels in the 3D-printed resin for removable denture bases.

Prótesis Totales Digitales 3D fabricadas por CAD-CAM: Revisión bibliográfica / 3D Digital Denture Complete manufactured by CAD-CAM: Literature review

El artículo se centra en la aplicación de tecnología CAD/CAM en la odontología, específicamente en la fabricación de prótesis dentales totales. Este avance ha transformado la forma en que se diseñan y producen estas prótesis, emergiendo la fabricación de ella mediante capas sucesivas a base de tecnologías de impresión 3D como la estereolitografía, el procesamiento digital de luz y la pantalla de cristal líquido. En la presente revisión se profundizó en aspectos clínicos y biomecánicos, evaluando la retención, adaptación de la base, resistencia a la flexión y límite elástico de las prótesis. Los resultados indican que las prótesis digitales ofrecen mejor retención y adaptación en comparación con los métodos convencionales, aunque no hay diferencias estadísticamente significativas en resistencia a la flexión. También se exploraron aspectos económicos, destacando la reducción de costos y ahorro de tiempo en el proceso clínico con el enfoque digital. Los pacientes experimentan mayor satisfacción con prótesis impresas en 3D en términos de comodidad y eficiencia. Sin embargo, existen limitaciones, como la dificultad en la evaluación estética de prótesis monocromáticas, además de la dependencia de técnicas convencionales para evaluar la funcionalidad del paciente. La tecnología CAD/CAM ha revolucionado la fabricación de prótesis dentales totales, ofreciendo ventajas y beneficios. Este avance tecnológico promete mantener su relevancia en la comunidad científica y odontológica.

The article focuses on the application of CAD/CAM technology in dentistry, specifically in the manufacturing of complete dentures. This advance has transformed the way these dentures are designed and produced, with the manufacturing of layers emerging through successive 3D printing technologies such as stereolithography, digital light processing and liquid crystal display. In the present review clinical and biomechanical aspects were delved into, evaluating retention, adaptation of the base, resistance to flexion and elastic limit of the prostheses. The results indicate that digital prostheses offer better retention and adaptation compared to conventional methods, although there are no statistically significant differences in bending resistance. Economic aspects were also explored, highlighting the cost reduction and time savings in the clinical process with the digital approach. Patients experience greater satisfaction with 3D printed dentures in terms of comfort and efficiency. However, there are limitations, such as the difficulty in the aesthetic evaluation of monochromatic dentures, in addition to the dependence on conventional techniques to evaluate the patient's functionality. CAD/CAM technology has revolutionized the manufacturing of total dental prostheses, offering advantages and benefits. These technological advance promises to maintain its relevance in the scientific and dental community.

Accuracy and time efficiency of conventional and digital outlining of extensions of denture foundation on preliminary casts.

PURPOSE: The purpose of this diagnostic study was to assess the accuracy and time efficiency of a digital method to draw the denture foundation extension outline on preliminary casts compared with the conventional technique. MATERIALS AND METHODS: A total of 28 preliminary edentulous casts with no anatomical landmarks were digitized using a laboratory scanner. The outlining of the entire basal seat of the denture was performed on preliminary casts and digitized. Casts with no extension outline were digitized and outlines were drawn using software (DWOS, Straumann). The accuracy of the extension outlined between both techniques was evaluated in the software (GOM Inspect; GOM GmbH) by file superimposition. Specificity and sensitivity tests were applied to measure accuracy. The paired t-test (95% CI) was used to compare the mean total area and the working time. RESULTS: The accuracy ranged from 0.57 to 0.92. The buccal and labial frenulum showed a lower value in the maxilla (0.57); while the area between the retromolar pad and buccal frenulum (0.64) showed a lower score in the mandible. The maxillary denture foundation and the working time for both arches were significantly longer for the digital method (P < .001). CONCLUSION: The denture foundation extension outline exhibited a sufficiently excellent accuracy for the digital method, except for the maxillary anterior region. However, the digital method required a longer working time.

New scenarios for training in oral radiology: clinical performance and predoctoral students' perception of 3D-printed mannequins.

OBJECTIVES: This study aimed to evaluate the impact of 3D-printed mannequins on the training of predoctoral students. METHODS: Two 3D-printed training models were developed: a traditional model that simulates a sound adult patient and a customized model with pathological and physiological changes (impacted third molar and edentulous region). Students accomplished their pre-clinical training divided into a control group (CG, n = 23), which had access to the traditional model, and a test group (TG, n = 20), which had access to both models. Afterward, they performed a full mouth series on patients and filled out a perception questionnaire. Radiographs were evaluated for technical parameters. Descriptive statistics and the Mann-Whitney test were used to compare the groups. RESULTS: Students provided positive feedback regarding the use of 3D printing. The TG reported a more realistic training experience than the CG (P = .037). Both groups demonstrated good clinical performance (CG = 7.41; TG = 7.52), and no significant differences were observed between them. CONCLUSIONS: 3D printing is an option for producing simulators for pre-clinical training in Oral Radiology, reducing student stress and increasing confidence during clinical care.

Guided coronally advanced flap to treat gingival recession: Digital workflow and case report.

BACKGROUND: The inherently technique-sensitive nature of periodontal plastic procedures demands a significant level of skill and expertise. The incorporation of three-dimensional (3D) printing technologies emerges as a potential strategy to optimize and simplify surgical procedures. This case report describes the digital workflow and presents the clinical outcomes achieved using a guided coronally advanced flap for the treatment of a single gingival recession (GR). METHODS AND RESULTS: A female patient with a gingival recession type 1 (RT1 B-) defect on the mandibular second left premolar underwent successful treatment using a guided coronally advanced flap (g-CAF) and de-epithelized connective tissue graft (CTG). The digital planning included intraoral scanning of the mandible and hard palate using an intraoral scanner, with resulting polygon format (PLY) files exported for virtual model creation. The CAF guide was meticulously designed to orient horizontal and vertical incisions at the papillae base adjacent to the GR defect. For the donor site, a guide was specifically created, positioning the graft area 2 mm apically to the premolars' gingival margins. The delineation of this area involved two horizontal and vertical incisions, meticulously based on the dimensions of the GR. The digitally designed guides were then 3D-printed using a surgical guide-specific resin, contributing to the precise execution of the innovative surgical approach. Complete root coverage was achieved. CONCLUSION: This case report demonstrates that g-CAF can be a promising approach for the treatment of single GR. HIGHLIGHTS: Why is this case new information? To the best of the authors' knowledge, this is the first manuscript to report a guided procedure for the treatment of gingival recession. This report provides the digital workflow for the fabrication of a guide to perform the coronally advanced flap for single recession defects. What are the keys to successfully manage this case? It is necessary to adequately scan the recession defect area and palate. Properly not only design the guide using specific software but also print it. The guide has to be stable when in position for the surgical procedure. What are the primary limitations of this technique? This guide was designed to help surgeons during the incisions. However, it does not provide aid to split and release the flap and suture.

An in vitro study using confocal laser scanning microscopy to evaluate the marginal misfits of different implant-supported frameworks.

PURPOSE: This study aimed to develop and evaluate a simple, non-destructive method for assessing the misfit and passivity of implant-retained prostheses frameworks. MATERIALS AND METHODS: To simulate the rehabilitation of a mandible posterior partially edentulous area using 3-unit screw-retained frameworks supported by two implants were fabricated and divided into the following five groups (n = 10 in each group): OP = one-piece framework cast in Co-Cr with the conventional method (control-group); Co-Cr frameworks sectioned and welded by laser (=LAS) or tungsten inert gas (=TIG); Co-Cr CAD-CAM = milled Co-Cr framework; Zir CAD-CAM = milled zirconia framework. The horizontal |X| and vertical |Y| misfits were measured using confocal laser scanning microscopy with one or both screws tightened. Data were analyzed by a two-way ANOVA with repeated measures and Bonferroni correction (α = 0.05). RESULTS: The greatest |X| misfit was observed in the OP group with both screws tightened (290 µm) and one screw tightened (388 and 340 µm). The conventional casting groups sectioned and welded by laser or TIG had lower mean values (235.35 µm, both screws tightened; and 275 µm, one screw tightened) than the OP framework. However, these values still exceeded those of the milled Co-Cr and zirconia frameworks (190 and 216 µm with both screws tightened). Across all reading conditions, every framework subjected to testing consistently maintained vertical |Y| misfit levels below the threshold of 53 µm; however, the milled frameworks exhibited higher vertical misfits than the frameworks obtained by the conventional cast method. CONCLUSIONS: The frameworks, whether cast and sectioned with laser welding or milled from Co-Cr, exhibit improved marginal misfit and enhanced passive fit when compared to other fabrication methods. Additionally, the use of confocal laser scanning microscopy is highly effective for passivity and misfit analysis.

Impresiones digitales dentales con escáneres intraorales: una revisión de la literatura / Dental digital impressions with intraoral scanners: a review of the literature / Impressões digitais dentárias com scanners intraorais: uma revisão da literatura

RESUMEN El diseño asistido por computadora y la fabricación asistida por ordenador (CAD-CAM, por sus siglas en inglés) se ha aplicado en odontología para la confección y el análisis de diversos tratamientos dentales. Inicia con la captura de imágenes a través de escáneres intraorales, contando con diversos tipos de softwares y sistemas de exportación de imágenes y tecnología. Las ventajas de este flujo de trabajo digital son el mejor ajuste, el empleo de menor tiempo clínico y la celeridad en tratamientos dentales, además de que brinda una mayor practicidad en el uso de los cirujanos dentistas. La precisión que brinda es clínicamente aceptable en comparación con los métodos convencionales, por lo cual existe suficiente evidencia para su validez; sin embargo, se debe tener en cuenta que diversos factores pueden alterar el resultado, como la experiencia del operador, el tipo de escáner, el tipo de software, la actualización del software, el principio de escaneo del escáner, el ambiente, la secuencia de escaneo y las estructuras bucales. El presente artículo de revisión tiene como objetivo analizar la literatura sobre las diferentes características y propiedades que presentan los escáneres intraorales en la actualidad, así como la evidencia de los posibles beneficios y la precisión de las técnicas de impresión digital frente a las técnicas de impresión convencionales.

ABSTRACT Computer-aided design and computer-aided manufacturing (CAD-CAM) has been applied in dentistry for the preparation and analysis of various dental treatments. It starts with capturing images through intraoral scanners, having different types of software and image export systems and technology. The advantages of this digital workflow are the following: better adjustment, shorter clinical time, and speed in dental treatments, in addition to providing greater practicality for dental surgeons. The accuracy he provide is clinically acceptable in comparison with conventional methods, so there is sufficient evidence for their validity; however, it should be taken into account that several factors can alter the result, such as the operator's experience, the type of scanner, the type of software, the software update, the scanning principle of the scanner, the environment, the scanning sequence, and the oral structures. The present review article aims to analyze the literature on the different characteristics and properties that intraoral scanners present today and the evidence of the potential benefits and accuracy of digital impression techniques versus conventional impression techniques.

RESUMO O desenho assistido por computador e o fabrico assistido por computador (CAD-CAM) têm sido aplicados na medicina dentária para a preparação e análise de vários tratamentos dentários. Começa com a captura de imagens através de scanners intraorais, com vários tipos de software e sistemas e tecnologia de exportação de imagens. As vantagens deste fluxo de trabalho digital são as seguintes: melhor ajuste, menor tempo clínico, rapidez nos tratamentos dentários, além de proporcionar maior praticidade no uso dos cirurgiões-dentistas. A precisão que proporcionam é clinicamente aceitável quando comparada com os métodos convencionais, pelo que existem evidências suficientes para a sua validade; no entanto, deve ter-se em conta que vários fatores podem alterar o resultado, tais como a experiência do operador, o tipo de scanner, o tipo de software, a atualização do software, o princípio de digitalização do scanner, o ambiente, a sequência de digitalização e as estruturas orais. Este artigo de revisão tem como objetivo analisar a literatura sobre as diferentes características e propriedades dos scanners intraorais atuais, bem como a evidência dos potenciais benefícios e precisão das técnicas de moldagem digital em comparação com as técnicas de moldagem convencionais.

Evaluation of surface roughness, wettability and adhesion of multispecies biofilm on 3D-printed resins for the base and teeth of complete dentures

Abstract Studies evaluating the roughness, wettability and microbial adhesion of 3D-printed resins for complete denture bases and teeth are scarce. Objective This study evaluated the surface roughness, wettability and adhesion of multispecies biofilms (Candida albicans, Staphylococcus aureus and Streptococcus mutans) on 3D-printed resins for complete denture bases and teeth compared to conventional resins (heat-polymerized acrylic resin; artificial pre-fabricated teeth). Methodology Circular specimens (n=39; 6.0 mm Ø × 2.0 mm) of each group were subjected to roughness (n=30), wettability (n=30) and biofilm adhesion (n=9) tests. Three roughness measurements were taken by laser confocal microscopy and a mean value was calculated. Wettability was evaluated by the contact angle of sessile drop method, considering the mean of the three evaluations per specimen. In parallel, microorganism adhesion to resin surfaces was evaluated using a multispecies biofilm model. Microbial load was evaluated by determining the number of Colony Forming Units (CFU/mL) and by scanning electron microscopy (SEM). Data were subjected to the Wald test in a generalized linear model with multiple comparisons and Bonferroni adjustment, as well as two-way ANOVA (α=5%). Results The roughness of the conventional base resin (0.01±0.04) was lower than that of the conventional tooth (0.14±0.04) (p=0.023) and 3D-printed base (0.18±0.08) (p<0.001). For wettability, conventional resin (84.20±5.57) showed a higher contact angle than the 3D-printed resin (60.58±6.18) (p<0.001). Higher microbial loads of S. mutans (p=0.023) and S. aureus (p=0.010) were observed on the surface of the conventional resin (S. mutans: 5.48±1.55; S. aureus: 7.01±0.57) compared to the 3D-printed resin (S. mutans: 4.11±1.96; S. aureus: 6.42±0.78). The adhesion of C. albicans was not affected by surface characteristics. The conventional base resin showed less roughness than the conventional dental resin and the printed base resin. Conclusion The 3D-printed resins for base and tooth showed less hydrophobicity and less adhesion of S. mutans and S. aureus than conventional resins.

Utilidad de la tecnología CAD/CAM en la fabricación de prótesis dentales

La tecnología CAD/CAM es una forma innovadora relacionada con la implementación de técnicas digitales para mejorar las restauraciones prostéticas en un paciente, entre ellas, las destinadas a la estética dental. El presente estudio tiene el objetivo de describir la utilidad de la tecnología CAD/CAM en la fabricación de prótesis dentales. Para ello se realizó una revisión de la literatura médica disponible en las bases de datos PubMed/Medline, Scopus y SciELO, mediante fórmulas de búsqueda avanzada; se seleccionaron artículos en idioma español e inglés. En la actualidad, con esta tecnología se ha logrado combinar estética, resistencia y precisión en la restauración directa, además de garantizarse una mayor duración y años de funcionalidad para cada una de las prótesis, coronas e implantes. La calidad de vida y satisfacción referidas por los pacientes portadores de piezas producidas con esta tecnología, es superior a las manifestadas por aquellos tratados con piezas de fabricación tradicional. El uso de técnicas de inteligencia artificial y biomateriales representará un cambio cualitativo y cuantitativo en el uso de los sistemas CAD/CAM.

CAD/CAM technology is an innovative way related to the implementation of digital techniques to improve prosthetic restorations in a patient, including those intended for dental aesthetics. The objective of this study is to describe the usefulness of CAD/CAM technology in the dental prostheses manufacture. A review of the medical literature available in the PubMed/Medline, Scopus and SciELO databases was carried out, using advanced search formulas; Articles in Spanish and English were selected. Currently, with this technology it has been possible to combine aesthetics, resistance and precision in direct restoration, in addition to guaranteeing greater duration and years of functionality for each of the prostheses, crowns and implants. The quality of life and satisfaction reported by patients wearing parts produced with this technology is higher than those reported by those treated with traditionally manufactured parts. The use of artificial intelligence and biomaterials techniques will represent a qualitative and quantitative change in the use of CAD/CAM systems.

Microtensile bond strength of resin cements to 3-D printed and milled temporary restorative resins / Resistencia de unión en microtracción de cementos resinosos a resinas para provisionales impresas y fresadas

Abstract To evaluate the microtensile bond strength (µTBS) of two resin cements to 3D printed and milled CAD/CAM resins used for provisional fixed partial dentures. Blocks (5 x 5 x 5 mm) of three 3D-printed resins (Cosmos3DTemp / Yller; Resilab3D Temp / Wilcos and SmartPrint BioTemp, / MMTech) were printed (Photon, Anycubic Technology Co.). A milled material (VitaCAD-Temp, VITA) was used as control. Half the specimens were sandblasted and the rest were untreated. Two blocks were bonded with the corresponding resin cement: PanaviaV5 (Kuraray Noritake) and RelyX Ultimate (3M Oral Care). After 24 hours, the bonded blocks were sectioned into 1 x 1 mm side sticks. Half the beams were tested for µTBS and the other half was thermocycled (5000 cycles, 30s dwell-time, 5s transfer time) before µTBS testing. A four way Generalized Linear Model (material*sandblasting*cement*aging) analysis was applied. VITA exhibited the lowest µTBS, regardless of the cement, sandblasting and thermocycling. Sandblasting significantly improved the µTBS of VIT, especially after aging, but did not improve the µTBS of 3D printed resins. Sandblasting was not beneficial for 3D printed resins, although is crucial for adhesive cementation of milled temporary resins. Airborne particle abrasion affects the integrity of 3D-printed resins, without producing a benefit on the microtensile bond strength of these materials. However, sandblasting is crucial to achieve a high bond strength on milled temporary resins.

Resumen Evaluar la resistencia adhesiva en microtracción (µTBS) de dos cementos resinosos a resinas CAD/CAM impresas y fresadas indicadas para restauraciones provisionales. Bloques (5 x 5 x 5mm) de tres resinas impresas (Cosmos3DTemp / Yller; Resilab3D Temp / Wilcos and SmartPrint BioTemp, / MMTech) y una resina fresada (VitaCAD-Temp, VITA) fueron fabricados. La mitad de los especímenes fueron arenados y el resto no recibió tratamiento mecánico. Dos bloques con condiciones de tratamiento iguales fueron cementados con cemento resinoso (PanaviaV5 / Kuraray Noritake y RelyX Ultimate / 3M Oral Care). Después de 24 horas los bloques fueron seccionados en palitos de 1 mm² de área. En la mitad de los especímenes se midió la TBS inmediatamente y el resto fue termociclado (5000 ciclos, 30s remojo, 5s transferencia) antes de la prueba de TBS. Se aplica un análisis estadístico por Modelo Linear General con 4 factores (material*arenado*cemento*termociclado). La resina VITA presentó la menor µTBS, independientemente del cemento usado, el arenado y el termociclado. Sin embargo, el arenado aumentó la µTBS de VIT, especialmente después del termociclado. Por otro lado, el arenado no resultó en un aumento significativo de la µTBS de las resinas impresas. El arenado no fue beneficiosos para las resinas impresas, aunque es un paso crucial para la cementación adhesive de las resinas fresadas. El arenado afecta la integridad de las capas de las resinas impresas, sin generar un beneficio en la TBS.

Effect of artificial aging on mechanical and physical properties of CAD-CAM PMMA resins for occlusal splints.

PURPOSE: This study aimed to assess and compare the color stability, flexural strength (FS), and surface roughness of occlusal splints fabricated from heat-cured acrylic resin, milled polymethyl methacrylate (PMMA)-based resin, and 3D-printed (PMMA) based-resin. MATERIALS AND METHODS: Samples of each type of resin were obtained, and baseline measurements of color and surface roughness were recorded. The specimens were divided into three groups (n = 10) and subjected to distinct aging protocols: thermomechanical cycling (TMC), simulated brushing (SB), and control (without aging). Final assessments of color and surface roughness and three-point bending test (ODM100; Odeme) were conducted, and data were statistically analyzed (2-way ANOVA, Tukey, P <.05). RESULTS: Across all resin types, the most significant increase in surface roughness (Ra) was observed after TMC (P < .05), with the 3D-printed resin exhibiting the lowest Ra (P < .05). After brushing, milled resin displayed the highest Ra (P < .05) and greater color alteration (ΔE00) compared to 3D-printed resin. The most substantial ΔE00 was recorded after brushing for all resins, except for heat-cured resin subjected to TMC. Regardless of aging, milled resin exhibited the highest FS (P < .05), except when compared to 3D-printed resin subjected to TMC. Heat-cured resin exposed to TMC demonstrated the lowest FS, different (P < .05) from the control. Under control conditions, milled resin exhibited the highest FS, different (P < .05) from the brushed group. 3D-printed resin subjected to TMC displayed the highest FS (P < .05). CONCLUSION: Among the tested resins, 3D-printed resin demonstrated superior longevity, characterized by minimal surface roughness and color alterations. Aging had a negligible impact on its mechanical properties.

Técnicas de montagem em articulador para confecção de placas oclusais pelo fluxo digital: efeito no tempo de trabalho / Articulator assembly techniques for manufacturing occlusal splints using digital flow: effect on working time

Objetivo: Avaliar a influência de diferentes tipos de registros interoclusais e técnicas de montagem em articulador virtual no tempo de confecção clínico e laboratorial de placas oclusais estabilizadoras confeccionadas por fluxo de trabalho digital (CAD/CAM). Metodologia: Trata-se de um ensaio clínico, onde a amostra foi constituída por 30 pacientes com diagnóstico de um provável bruxismo do sono, os quais foram randomizados aleatoriamente em dois grupos de acordo com a técnica de montagem do modelo no articulador virtual: GP (grupo plano horizontal) e GM (grupo mesa de camper). Também foram avaliados três diferentes tipos de registros interoclusais para confecção de placas oclusais impressas, sendo: "máxima intercuspidação habitual" (MIH), "dispositivo anterior de registro" (DAR) e "palhetas oclusais"; e as técnicas de desenho das placas oclusais sendo essas etapas subdivididas em suavização e delimitação, montagem do modelo do modelo superior no articulador (variando em plano horizontal e mesa de camper), desenho da placa e ajustes finais. A partir disso, foram analisados os tempos (em minutos e segundos) necessários para a realização das etapas clínicas e laboratoriais (etapas CAD ­ obtenção dos arquivos e desenho da placa). Os dados foram avaliados estatisticamente pelos testes T, ANOVA e Tukey pelo software Statistical Package for Social Sciences 22.0. Resultados: Observou-se diferença estatística no tempo de registro interoclusal, onde MIH (47,94seg) e palheta (01:03,01min) foram realizados em um menor tempo quando comparado com o DAR (03:09,26min) (<0,001). O tempo da etapa de montagem no articulador foi estatisticamente maior quando o registro foi realizado em MIH e a montagem foi realizada levantando no pino no articulador (01:59,62min), comparando ao DAR (01:07,82min) e a palheta (01:06,43min) (<0,001), apresentando também diferença no tempo de desenho (p=0,045) e tempo total das etapas (p=0,033). Conclusão: Dentro das limitações do estudo, pode-se afirmar que utilizar a palheta oclusal ou registrar em MIH apresentaram um menor tempo clínico quando comparada à técnica do DAR. Levantar o pino no articulador levou a um maior tempo de montagem dos modelos, independente do modelo ter sido montado no plano horizontal ou na mesa de camper, aumentado o tempo na etapa CAD (AU).

Objective: To evaluate the influence of different types of interocclusal registrations and assembly techniques in a virtual articulator on the clinical and laboratory preparation time of stabilizing occlusal splints made by digital workflow (CAD/CAM). Methodology: This is a clinical trial, where the sample consisted of 30 patients diagnosed with sleep bruxism, who were randomly randomized into two groups according to the technique of mounting the model on the articulator virtual: GP (flat horizontal group) and GM (camper's table group). Three different types of interocclusal records were also evaluated for making printed occlusal plates, namely: "maximum habitual intercuspation" (MIH), "anterior recording device" (DAR) and "occlusal reeds"; and the techniques for designing the occlusal splints, these steps being subdivided into smoothing and delimitation, mounting the model of the upper model on the articulator (varying in the horizontal plane and camper's table), designing the plate and final adjustments. Based on this, the times (in minutes and seconds) required to perform the clinical and laboratory steps were analyzed. Data were statistically evaluated by T, ANOVA and Tukey tests using the Statistical Package for Social Sciences 22.0 software. Results: There was a statistical difference in the time of interocclusal registration, where MIH (47.94sec) and reed (01:03.01min) were performed in a shorter time when compared to the DAR (03:09.26min) (<0.001 ). The time of the assembly step on the articulator was statistically longer when the registration was performed in MIH and the assembly was performed by lifting the pin on the articulator (01:59.62min), comparing to the DAR (01:07.82min) and the reed (01:07.82min) 01: 06.43min) (<0.001), also showing difference in design (p=0.045) and total time of steps (p=0.033). Conclusion: Within the limitations of the study, it can be stated that using the occlusal palette or registering in MIH demonstrated a shorter clinical time when detected using the RAD technique. Lifting the pin on the articulator led to a longer time to assemble the models, regardless of whether the model was mounted in the horizontal plane or on the camper's table, it increased the time in the CAD step (AU).

Surface wear and adhesive failure of resin attachments used in clear aligner orthodontic treatment.

PURPOSE: This study evaluated adhesive and cohesive failures and the surface wear of attachments employed in clear aligner treatment (CAT) using three-dimensional (3D) superimposition. METHODS: In all, 3D models of 150 teeth were obtained from intraoral scans from patients undergoing CAT with at least 4 months between each scan. Of the initial sample, 25 teeth were discarded, and 125 teeth were included in the study. Superimpositions of each individual tooth at the first and second time points were made using computer-aided design (CAD) software (Meshmixer; Autodesk, Mill Valley, CA, USA). Analyses were performed to compare surface wear and failures related to type of attachment (optimized/conventional), dental group (molars/premolars/anterior teeth), and arch (mandibular/maxillary). Mann-Whitney and Kruskal-Wallis statistical tests were applied with significance set at 5%. RESULTS: More surface wear was observed in conventional attachments, mandibular and anterior teeth with statistical significance for surface wear on the distal surface of conventional attachments (p < 0.05). Cohesive failure was observed in 10% of attachments, occurring most frequently on optimized attachments and molar teeth. Adhesive failure was observed in 10% of the samples, more frequently on conventional attachments and posterior teeth. CONCLUSION: Attachment type (conventional vs. optimized) was significantly correlated with surface wear on the distal surface of the attachment. Arch (mandibular or maxillary) and group of teeth (anterior or posterior) showed no correlation with surface wear. Failure, both adhesive and cohesive, correlated with attachment type and group of teeth, but not with the arch in which they were located.

The effect of abutment material stiffness on the mechanical behavior of dental implant assemblies: A 3D finite element study.

PURPOSE: This study aimed to evaluate the stress distribution and microgap formation in implant assemblies with conical abutments made of different materials under an oblique load. MATERIALS AND METHODS: The mechanical behavior of an implant assembly with a titanium abutment was analyzed and compared with that of an assembly with a Y-TZP abutment using finite element analysis (FEA). A torque of 20 Ncm was first applied to the abutment screw, followed by oblique loads of 10 N-280 N applied to the prosthesis placed on the implant. The maximum stress in the abutment screw, the microgap formation process, and the critical load for bridging the internal implant space were evaluated. RESULTS: No significant difference in stress distribution between the two cases was observed, with the stresses being mainly concentrated at the top half of the screw (the predicted maximum von Mises stress was approximately 1200 MPa at 280 N). The area in contact at the implant-to-abutment interface decreased with increasing load for both abutments, with the critical load for bridging the internal implant space being roughly 140 N. The maximum gap size being was approximately 470 µm with either abutment. CONCLUSION: There was no significant difference in the stress distribution or microgap formed between implant assemblies with titanium and Y-TZP abutments having an internal conical connection.

An Innovative 3D Printed Tooth Reduction Guide for Precise Dental Ceramic Veneers.

Tooth reduction guides allow clinicians to obtain the ideal space required for ceramic restorations. This case report describes a novel design (CAD) for an additive computer-aided manufactured (a-CAM) tooth reduction guide with channels that permitted access for the preparation and evaluation of the reduction with the same guide. The guide features innovative vertical and horizontal channels that permit comprehensive access for preparation and evaluation of the reduction with a periodontal probe, ensuring uniform tooth reduction and avoiding overpreparation. This approach was successfully applied to a female patient with non-carious lesions and white spot lesions, resulting in minimally invasive tooth preparations and hand-crafted laminate veneer restorations that met the patient's aesthetic demands while preserving tooth structure. Compared to traditional silicone reduction guides, this novel design offers greater flexibility, enabling clinicians to evaluate tooth reduction in all directions and providing a more comprehensive assessment. Overall, this 3D printed tooth reduction guide represents a significant advancement in dental restoration technology, offering clinicians a useful tool for achieving optimal outcomes with minimal tooth reduction. Future work is warranted to compare tooth reductions and preparation time for this guide to other 3D printed guides.

CAD-CAM natural restorations-Reproducing nature using a digital workflow.

OBJECTIVES: Natural restorations combine digital workflow and shell technique to create CAD/CAM restorations with the form and texture of natural teeth. This case report describes an interdisciplinary digital workflow combined with CAD/CAM natural restorations to achieve the naturalness of an anterior rehabilitation. CLINICAL CONSIDERATIONS: A 38-year-old patient attended to the office with esthetic issues. An interdisciplinary treatment plan was conducted, which included periodontal surgery to recreate the gingival contour, associated with bleaching and manufacturing CAD/CAM ceramic veneers to return an optimal teeth surface texture and shape. CONCLUSIONS: The design and manufacturing of CAD/CAM natural restorations using a digital workflow allowed a predictable result and overcame the limitations of conventional shell technique. CLINICAL SIGNIFICANCE: Conventional shell technique is used to create restorations with the form and texture of natural teeth. This article presents a combination of the conventional shell technique with a digital workflow, facilitating the design and manufacturing of CAD/CAM natural restorations.

Failure behavior of zirconia crowns subjected to air abrasion with different particle sizes

Abstract This study aimed to investigate the failure behavior of 3 mol.% yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) prosthetic crowns air-abraded with aluminum oxide (AO) particles of different sizes. Ninety ceramic premolar crowns were produced with 3Y-TZP frameworks veneered with porcelain. Crowns were randomly divided into three groups, according to the size of the air abrasion AO particles (n = 30): (GC) untreated (control); (G53) 53 µm; (G125) 125 µm. Air abrasion was performed with 0.25 mpa pressure, 10-mm distance, for 10 s. Crowns were adhesively cemented to dentin analog abutments. Specimens were loaded in compression to failure, in 37oC distilled water, using a universal testing machine (n = 30). Fractographic analysis was performed using a stereomicroscope and SEM. The roughness of the crown's inner surface was evaluated using an optical profilometer (n = 10). Fracture load data were statistically analyzed with Weibull analysis and roughness data with Kruskal-Wallis (α = 0.05). GC had the lowest characteristic fracture load (L0), while G53 and G125 had higher and statistically similar L0 values. The Weibull modulus (m) was similar among groups. The failure modes observed were catastrophic failure and porcelain chipping. There were no differences between the roughness parameters for the experimental groups (p > 0.05). The size of the AO particles did not affect the fracture load and failure mode of 3Y-TZP crowns. Air abrasion with 53 µm and 125 µm particles resulted in a higher fracture load of ceramic crowns than the untreated group while maintaining their reliability and surface characteristics.

Resumo O objetivo deste estudo foi investigar o efeito do jateamento com óxido de alumínio (AO) com diferentes tamanhos de partículas no comportamento de fratura de coroas protéticas de zircônia tetragonal estabilizada com 3 mol% de ítria (3Y-TZP). Noventa coroas cerâmicas de pré-molares foram produzidas com infraestruturas de 3Y-TZP recobertas com porcelana. As coroas foram divididas aleatoriamente em três grupos, de acordo com o tamanho das partículas de AO do jateamento (n = 30): (GC) não tratada (controle); (G53) 53 µm; (G125) 125 µm. O jateamento foi realizado com pressão de 0,25 MPa, distância de 10 mm, por 10 s. As coroas foram cimentadas adesivamente em pilares análogos à dentina. As coroas foram testadas em compressão até a falha, em água destilada a 37ºC, usando uma máquina universal de ensaios (n = 30). A análise fractográfica foi realizada usando estereomicroscópio e MEV. A rugosidade da superfície interna das coroas foi avaliada usando um perfilômetro óptico (n = 10). Os dados de carga de fratura foram analisados ​​estatisticamente com análise de Weibull e os dados de rugosidade com Kruskal-Wallis (( = 0,05). GC apresentou a menor carga característica de fratura (L0), enquanto G53 e G125 apresentaram valores de L0 maiores e estatisticamente semelhantes. O módulo de Weibull (m) foi semelhante entre os grupos. Os modos de falha observados foram falha catastrófica e lascamento da porcelana. Não houve diferenças entre os parâmetros de rugosidade para os grupos experimentais (p > 0,05). O tamanho das partículas de AO não afetou a carga de fratura e o modo de falha das coroas 3Y-TZP. O jateamento com partículas de 53 µm e 125 µm resultou em maior carga de fratura das coroas cerâmicas do que o grupo não tratado, mantendo sua confiabilidade e características de superfície.

Resin cement coating reverts the machining damage on the flexural fatigue strength of lithium disilicate glass-ceramic.

This study evaluated the effect of resin cement coating with high and low viscosities on the flexural fatigue strength of machined lithium disilicate glass-ceramic. Discs (IPS e.max CAD; Ivoclar Vivadent) were prepared and divided according to the surface condition (machining [M]-CEREC inLab; and polishing [P]-laboratory procedures), resin cement coating (with or without), and cement viscosity (high [H] and low [L]). The ceramic bonding surface was etched/primed by a one-step primer application followed by resin cement application (Variolink N base + high or low viscosity catalyst; Ivoclar Vivadent). Biaxial flexural fatigue strength was evaluated on a piston-on-three-ball set by the step-test method (n = 15) (initial stress: 60 MPa; incremental steps: 20 MPa; 10,000 cycles/step, at 20 Hz). Weibull statistics were used for fatigue data. Contact angle, topographic, and fractographic analysis were also performed. Machining produced statistically lower contact angle than polishing and a significant detrimental effect on the fatigue behavior (σ0 M = 247.2 [246.9-268.3]; σ0 P = 337.4 [297.8-382.4]). Machined groups followed by resin cement coating (σ0 MH = 297.9 [276.0-321.5]; σ0 Ml = 301.2 [277.1-327.4]) behaved similarly to the polished and coated groups (σ0 PH = 342.0 [308.9-378.5]; σ0 PL = 357.3 [324.7-393.1]), irrespective of the cement viscosity. Therefore, cement coating has able to revert the detrimental effects of the machining on the fatigue strength of lithium disilicate glass-ceramic. High and low viscosity cements behaved similarly in the improvement of CAD-CAM lithium disilicate fatigue strength.

Guided Access Cavity Preparation Using a New Simplified Digital Workflow.

INTRODUCTION: This study evaluated the precision of a simplified workflow using only preoperative cone-beam computed tomographic (CBCT) scans to gain guided access to root canals of extracted mandibular molars. A workflow using CBCT scanning associated with 3-dimensional oral scanning was used as a reference for comparison. The influence of the presence of coronal restoration in the simplified workflow was also evaluated. METHODS: Forty-five mandibular molars were randomized into 3 groups: a control group in which digital planning was performed with CBCT and oral scanning and 2 experimental groups in which digital planning was performed only with CBCT examination. In experimental group 1, teeth had no coronal restorations, whereas in group 2 teeth presented with coronal composite restorations. After digital planning, the teeth were accessed using the guides, and a new CBCT scan was made to overlap the pre- and postoperative examinations. Precision was measured by calculating the deviation between the planned and prepared cavities in millimeters and angle. Data were compared using 1-way analysis of variance (P < .05). RESULTS: All root canals were accessible after access preparation in all tested groups. Deviations of the planned and prepared access cavities were low, with a mean value of 0.55, 0.58, and 0.47 mm and 1.98°, 2.45°, and 1.43° for the control group, group 1, and group 2, respectively. No significant differences in millimeters or angle were observed among the 3 tested groups (P > .05). CONCLUSIONS: The simplified digital workflow using only CBCT examination allowed a high level of precision in obtaining access in extracted molars with and without coronal restoration, presenting similar results compared with the digital workflow using CBCT and 3-dimensional oral scanning.