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.

Digital repair for a patient with limited mouth opening: a case report and literature review / 口腔疾病防治

Objective@#To explore an accurate method to obtain an intraoral model of patients with specific limited mouth opening (microstomia) due to systemic scleroderma.@*Methods@#This study followed medical ethics, and informed consent has been obtained from patients. A case of Ken's Type I mandibular dentition defect scleroderma with limited mouth opening was addressed with digital technology as the leading method combined with the traditional impression method of segmental impression. Individual trays were made based on the patient's left and right mandibular dentition, and segmented molds were obtained. Simultaneously, intraoral scanning was performed to obtain the morphological data of both the soft and hard tissues of the upper and lower mandibles. After each part of the model was obtained, the mandibular model was scanned and digitally aligned to form the final denture model, and the final removable partial denture was designed and made by computer aided design/computer aided manufacturing (CAD/CAM) technology. At the same time, combined with the literature, the diagnosis and treatment of removable partial denture in patients with limited mouth opening were retrospectively analyzed.@*Results@#The denture was well retained and achieved a good repair effect. The patients expressed satisfaction with the mastication efficiency and other functions of the denture. The findings of the literature review show that the integration of digital technology with the traditional impression method, along with computer fitting, can accurately obtain the patient's oral model and facilitate successful follow-up repairs. However, when the anterior mandibular dentition of the patient is absent, the margin of error is increased in this procedure, which deserves further exploration.@*Conclusion@#Utilizing digital technology as the leading method, combined with the traditional impression method of segmental impression, for the repair of dental defects in patients with limited mouth opening, has proven to be effective. Thus, patients report a positive medical experience with high satisfaction, indicating that this approach is worthy of clinical promotion.

Challenges of computer-assisted orthognathic surgery in clinical application / 口腔疾病防治

@#After years of development, the advantages of computer-assisted orthognathic surgery have been widely recognized. However, the clinical application of this technology is challenging. Each step may generate errors from data acquisition, computer-assisted diagnosis, and computer-assisted surgical design, causing errors to be transferred from the virtual surgical plan to the operation. The accumulation and amplification of errors will affect the final surgical effect. Currently, digital devices, such as intraoral scanners, are being explored for error control, utilizing automation methods and algorithms, and implementing personalized bone positioning methods. Moreover, there are still many problems that have not been fully resolved, such as precise simulation of postoperative soft tissue, functional assessment of mandibular movement, and absorbable internal fixation materials. Fully understanding computer-assisted orthognathic surgery's limitations could provide direction for optimizing existing methods while helping clinicians avoid risks and maximize its advantages to achieve the best outcome. Many emerging and cutting-edge technologies, such as personalized titanium plates, artificial intelligence, and surgical robots, will further promote the development of this discipline. We can expect future optimization of digital orthognathic surgical technology by innovations in automation, intelligence, and personalization.

Clinical study of polyetheretherketone resin-bonded bridge for restoring anterior missing teeth in patients with periodontitis / 口腔疾病防治

Objective@#To study the clinical effect of a polyetheretherketone (PEEK) bonding bridge on the loss of 3 internal incisors in patients with periodontitis.@*Methods@#This study was reviewed and approved by the ethics committee, and informed consent was obtained from the patients. Thirty-eight patients with periodontitis and 3 missing central or lateral teeth were selected to undergo restoration with a PEEK bonding bridge and then returned to the hospital 3, 6, 12, and 24 months after the restoration was completed. The survival rate of the restorations was assessed by the modified USPHS/Ryge criteria. The plaque index, gingival index, periodontal probing depth and attachment loss of the abutments were recorded, and the changes in periodontal tissues after restoration were observed and compared.@*Results@#Over 24 months of clinical follow-up observation of 38 patients, only 1 patient underwent secondary bonding after partial debonding (evaluated as grade B), while bonding was successful in the other 37 cases (evaluated as grade A). The plaque index, gingival index and periodontal probing depth were significantly lower after restoration than before (P<0.05). There was no significant change in attachment loss between before and after restoration (P>0.05).@*Conclusion@#For periodontitis patients missing 3 internal incisors, short-term PEEK bonding bridge repair has good clinical efficacy.

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.

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.

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.

Translucency and masking ability of a translucent zirconia with different thicknesses over dark backgrounds / Translucidez e capacidade de mascaramento de uma zircônia translúcida com diferentes espessuras sobre substratos escuros

ABSTRACT Objectives: To evaluate the translucency, contrast ratio and masking ability of a translucent zirconia with different thicknesses. Methods: Disc shaped specimens (n= 3) with 10 mm (Ø) x 1.5 mm, 1 mm and 0.7 mm (thickness) were manufactured simulating all-ceramic simplified restorations. Substrate discs (n= 2; Ø: 10 mm; thickness: 2 mm) were simulated with composite resin shades: A2 (positive control) and C4; and metal alloys: silver (Ni-Cr) and golden (Cu-Al). Optical properties of the 9 translucent zirconia specimens placed on the 3 different substrates were analyzed by a spectrophotometer. The color variation (ΔE00) between each ceramic structure over the positive control substrate (A2) and over the dark backgrounds (C4, silvery, golden) were obtained as to their ceramic masking ability and subjected to non-parametric Kruskal Wallis test (5%). The translucency parameter (TP00) and contrast ratio (CR) of the different thicknesses of the ceramic discs were also collected and analyzed by one-way ANOVA and the Tukey test (5%). Results: The translucent zirconia showed greater opacity in the thickness of 1.5 mm, although it was not statistically different between 0.7 and 1.0 mm. All dark backgrounds significantly affected the final color of the simplified restoration in all evaluated thicknesses. However, the increase in ceramic thickness showed a decrease in ΔE00 values for all substrates. Conclusion: The translucent zirconia was not able to mask the dark substrates, independent of the evaluated thickness.

RESUMO Objetivos: Avaliar a translucidez, razão de contraste e capacidade de mascaramento de uma zircônia translúcida com diferentes espessuras. Métodos: Espécimes em forma de disco (n= 3) com 10 mm (Ø) x 1,5 mm, 1 mm e 0,7 mm (espessura) foram confeccionados simulando restaurações simplificadas em cerâmica pura. Discos de substrato (n= 2; Ø: 10 mm; espessura: 2 mm) foram simulados com as cores de resina composta: A2 (controle positivo) e C4; e ligas metálicas: prata (Ni-Cr) e ouro (Cu-Al). As propriedades ópticas dos 9 espécimes de zircônia translúcida posicionados nos 3 substratos diferentes foram analisadas por um espectrofotômetro. A variação de cor (ΔE00) entre cada espécime cerâmico sobre o substrato controle positivo (A2) e sobre os fundos escuros (C4, prateado, dourado) foi calculada quanto à capacidade de mascaramento da cerâmica e submetida ao teste não paramétrico de Kruskal Wallis (5%). O parâmetro de translucidez (TP00) e a razão de contraste (CR) das diferentes espessuras dos discos cerâmicos também foram coletados e analisados por ANOVA de uma via e teste de Tukey (5%). Resultados: A zircônia translúcida apresentou maior opacidade na espessura de 1,5 mm, embora não tenha sido estatisticamente diferente entre 0,7 e 1,0 mm. Todos os fundos escuros afetaram significativamente a cor final da restauração simplificada em todas as espessuras avaliadas. No entanto, o aumento da espessura da cerâmica mostrou uma diminuição nos valores de ΔE00 para todos os substratos. Conclusão: A zircônia translúcida não foi capaz de mascarar os substratos escuros, independente da espessura avaliada.

A clinical evaluation of zirconia reinforced lithium silicate glass-ceramic CAD/CAM onlay: a two-year case report / Avaliação clínica de onlay cerâmica do tipo CAD / CAM de silicato de lítio reforçado com zircônia: um relato de caso de dois anos

ABSTRACT The CAD/CAM technology arose from the need to develop materials with better mechanical and optical properties that could be used for making monolithic restorations. Several materials have been used for milling indirect restorations in prefabricated blocks. Among them, lithium silicate reinforced with zirconia. Due to its recent introduction in the market, this case report aimed to present a detailed clinical protocol for the execution of a ceramic onlay of this material using CAD/CAM technology. A 57-year-old female patient sought care with extensive restoration in composite resin (BOMD) of tooth 15 maintained for almost two years. However, due to bruxism, constant dental tightening, the extension of the direct restoration and the need for improved esthetics, it was proposed to replace it with an indirect ceramic onlay restoration. Prophylaxis and choice of the color of the patient's dental substrate were performed. Afterwards, the dental preparation was made and polished. Subsequently, the molding was made with addition silicone and the provisional restoration confectioned. Once the stone model was obtained, it was scanned and the ceramic onlay restoration was milled using CAD/CAM technology. Finally, the restoration was stained and cemented over the preparation. After 2 years, the restoration remained stable, with no evidence of color mismatch, marginal discoloration, marginal cleft, caries or fracture, proving the effectiveness of the treatment in this time interval. The correct indication of the ceramic material combined with the use of CAD/CAM technology facilitated the restorative process, restoring function and the esthetics desired by the patient.

RESUMO A tecnologia CAD/CAM surgiu da necessidade de desenvolvimento de materiais com melhores propriedades mecânicas e ópticas que pudessem ser utilizados para confecção de restaurações monolíticas. Diversos materiais têm sido utilizados para fresagem de restaurações indiretas em blocos pré-fabricados. Dentre eles, o silicato de lítio reforçado com zircônia. Devido a sua recente introdução no mercado, este relato de caso objetivou apresentar um protocolo clínico detalhado para a execução de uma onlay cerâmica desse material utilizando a tecnologia CAD/CAM. Paciente, 57 anos, sexo feminino, procurou atendimento com extensa restauração em resina composta envolvendo as faces (MODV) do dente 15 mantida por quase dois anos. Contudo, em virtude do bruxismo, do apertamento dental constante, da extensão da restauração direta e da necessidade de melhora na estética, foi proposto a substituição por uma restauração indireta em cerâmica do tipo onlay. Foi realizada a profilaxia e escolha da cor do substrato dental da paciente. Em seguida o preparo dental foi confeccionado e polido. Posteriormente foi feita a moldagem com silicone de adição e a confecção do provisório. Com a obtenção do modelo, este foi escaneado e fresada a onlay cerâmica pela tecnologia CAD/CAM, que posteriormente foi maquiada e cimentada sobre o preparo. Após 2 anos, a restauração permaneceu estável, sem evidência de incompatibilidade de cor, descoloração marginal, fenda marginal, cárie ou fratura, comprovando a eficácia do tratamento neste intervalo de tempo. A correta indicação do material cerâmico aliada ao uso da tecnologia CAD-CAM facilitou o processo restaurador devolvendo função e a estética desejada pela paciente.

Bonding performance of universal adhesives with concomitant use of silanes to CAD/CAM blocks / Associação de adesivos universais com silanos na adesão em blocos de CAD/CAM

ABSTRACT Objective: This study assessed whether the use of a silane coupling agent influence the bond strength of two universal adhesives to ceramic or resin CAD/CAM blocks. Methods: Forty-eight samples were obtained from each resin nano-ceramic hybrid block (RCBs) and lithium disilicate ceramic blocks (LD). Samples were treated with silane with MDP (Monobond - S-MDP), silane without MDP (Prosil - PS), and no silane application (Control - Ctr) followed by universal adhesive with silane (UAS) and without silane (UA) (n=8). Three polyurethane tubes (1.5 mm of internal diameter) were positioned in each sample treated surface and filled with a dual cured resin cement. Bond strength was assessed by microshear bond strength test and failure analysis was performed for all samples. Results: For the RCBs, UAS presented the highest bond strength values (p=0.004). Silane application was not significant in bond strength values (p=0.444). For LD, silane application was significant in bond strength values (p<0.001), but the adhesive was not (p=0.066). Failure analysis showed high prevalence of adhesive failures for both substrates. Conclusion: A silane-containing universal adhesive promoted the best bond strength results to the resin nano-ceramic hybrid block. For bonding to a glass-ceramic CAD/CAM material, additional silane (without MDP) application presented the best results.

RESUMO Objetivo: Este estudo avaliou se o uso de um agente de união silano influencia na resistência de união de dois adesivos universais a blocos CAD/CAM cerâmicos ou resinosos. Métodos: Quarenta e oito amostras foram obtidas de blocos resinosos (RCBs) e cerâmicos de dissilicato de lítio (LD). As amostras foram tratadas com silano contendo: MDP (Monobond - S-MDP), silano sem MDP (Prosil - PS) ou sem aplicação de silano (Control - Ctr) seguido de adesivo universal com silano (UAS) ou sem silano (UA) (n=8). Três tubos de poliuretano (1,5 mm de diâmetro interno) foram posicionados em cada superfície tratada da amostra e preenchidos com um cimento resinoso dual. A resistência de união foi avaliada pelo teste de microcisalhamento e a análise de falha foi realizada para todas as amostras. Resultados: Para os RCBs, UAS apresentou os maiores valores de resistência de união (p=0,004). A aplicação de silano não foi significativa nos valores de resistência adesiva (p=0,444). Para LD, a aplicação de silano foi significativa nos valores de resistência de união (p<0,001), mas o adesivo não (p=0,066). A análise de falhas mostrou alta prevalência de falhas adesivas para ambos os substratos. Conclusão: O adesivo universal contendo silano promoveu os melhores valores de resistência adesiva ao bloco de resina. Para o bloco cerâmico, a aplicação adicional de silano (sem MDP) apresentou melhores resultados.

A systematic review and meta-analysis of the clinical performance of implant-supported overdentures retained by CAD-CAM bars

Abstract Currently, there is no consensus on the indications and clinical performance of implant-supported overdentures (IODs) involving computer-aided design and manufacturing (CAD-CAM) bars. Objective: To evaluate the performance of IODs involving CAD-CAM bars. Methodology: A comprehensive search of studies published until May 2023 was conducted in many databases, including PubMed/MEDLINE, Web of Science, Cochrane Library, and SciELO, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The population, intervention, comparison, outcome (PICO) question was: "How do IODs retained by bars fabricated by CAD-CAM technology perform in daily clinical practice?" The meta-analysis included clinical studies based on effect size and a two-tailed null test with a 95% confidence interval (CI). Results: Ten studies were included in the meta-analysis. Among them, nine reported a 100% implant survival rate for all CAD-CAM milled bars. Complications were reported in two studies with CAD/CAM-milled titanium bars, and one study reported more fractures in soldered gold bars used in maxillary rehabilitation. However, no fractures were observed in IODs retained by PEEK and zirconia bars. According to six studies, biological complications, including peri-implantitis, were minimal in the BioHPP and PEEK bar groups, while no cases were reported in the titanium or zirconia bar groups. CAD-CAM-milled zirconia bars had higher plaque and bleeding indices compared with titanium bars, as evidenced by findings from five studies. All four studies that evaluated Oral Health Impact Profile (OHIP) scores showed a positive effect of IODs retained by CAD-CAM milled titanium bars on quality of life. Patient satisfaction and acceptance by prosthodontists were significantly high, according to the results of five studies. Conclusion: Overdentures retained with CAD-CAM milled titanium bars show great potential for use in daily clinical practice. Moreover, patient and practitioner satisfaction was very high when this method was used.

Peri-implant bone level assessment of early loaded dental implants submitted to different prosthetic protocols: a case report / Avaliação do nível ósseo peri-implantar de implantes dentários com carregamento antecipado submetidos a protocolos protéticos diferentes: relato de caso

Aim: The present split-mouth case report aims to describe the clinical and radiographic long-term outcomes of the implant rehabilitation of two mandibular premolars in which the digital workflow was used to apply different prosthetic protocols. Case description: A female 42-year-old patient with the absence of both mandibular second premolars was submitted to guided surgery for the placement of platform-switching Grand Morse connection implants. Digital workflow was used for implant and prosthetic planning, applying early loading protocol 21 days after surgery. The implant on the right side received the final abutment at the time of surgery (without loading), whereas the implant on the left side had a healing abutment placed, which was replaced by a temporary abutment and then by a final abutment. Two months after surgery, both implants had final ceramic restorations delivered. The patient was followed clinically and radiographically for 30 months, presenting excellent hard and soft tissue outcomes, with bone level changes lower than 2mm for both implants. Conclusion: The use of digital workflow and early loading, made the present implant-supported rehabilitation predictable, safe and time-efficient, resulting in total patient satisfaction. Peri-implant bone level was observed to be stable after early loading protocol for both platform-switching connection implants inserted, despite the prosthetic protocol applied.(AU)

Objetivo: O presente relato de caso de boca dividida tem como objetivo descrever os resultados clínicos e radiográficos a longo prazo da reabilitação com implante de dois pré-molares inferiores em que o fluxo de trabalho digital foi usado para aplicar os conceitos de "one abutment-one time" em uma das reabilitações e troca de componente no outro. Descrição do caso: Paciente do sexo feminino, 42 anos, com ausência de ambos os segundos pré-molares inferiores, foi submetida à cirurgia guiada para colocação de implantes de conexão Grand Morse plataforma-switching. Foi utilizado fluxo de trabalho digital para planejamento de implante e prótese, aplicando protocolo de carga antecipada 21 dias após a cirurgia. O implante do lado direito recebeu o componente protético definitivo no momento da cirurgia (sem carga), enquanto o implante do lado esquerdo recebeu um cicatrizador, que foi substituído por um pilar provisório e depois por um componente definitivo. Dois meses após a cirurgia, ambos os implantes tiveram restaurações cerâmicas finais entregues. A paciente foi acompanhada clínica e radiograficamente por 30 meses, apresentando excelentes resultados de tecidos duros emoles, com alterações do nível ósseo inferiores a 2mm para ambos os implantes. Conclusão: O fluxo de trabalho digital e carregamento precoce, tornou a presente reabilitação implantossuportada previsível, segura e eficiente em termos de tempo, resultando em total satisfação do paciente. O nível ósseo peri-implantar foi observado como estável após o protocolo de carregamento inicial para ambos os implantes de conexão plataforma-switching inseridos, independente do protocolo protético aplicado. (AU)

Use of scanning electron microscope to evaluate the marginal fit of protocol bars obtained through benchtop or intraoral digital scanners

Aim: To evaluate the marginal fit of protocol bars milled from digital models obtained by conventional molding followed by bench scanning or digital molding with an intraoral scanner. Methods: Four morse-cone implants and the mini-pillars were installed in a 3D printed mandible model (master model). Digital models of the master model were obtained by (n=10): (Group A - Conventional) conventional (analog) molding of the master model followed by bench scanning or (Group B - Digital) molding of the master model with an intraoral scanner. All-on-four protocol bars were designed and milled from the digital models for both groups and screwed into the master model. Scanning electron microscopy (SEM) images from the distal, central, and mesial regions of each implant were obtained and the implant-protocol bar marginal fit was measured in an image software (Image J). The mean misfit of each region was analyzed by two-factor ANOVA, Tukey test, and Student's t-test (0,05 = 0.05). Results: The digital approach (B) showed higher misadaptation than the conventional approach (A, p < 0.05), regardless of the region evaluated. In group A, the central region showed higher maladjustment than the mesial region (p<0.05), however, there were no differences among regions of group B (p>0.05). Conclusion: The conventional method of acquiring digital models using the bench scanner produced bars for the All-On-Four protocol with better marginal fit than the digital models obtained with an intraoral scanner

Digital design and 3D-printed customized flanged cups in hip revision with severe acetabular bone defects / 中华骨科杂志

Objective:To investigate the effect of 3D-printed customized flanged cup in hip revision with severe acetabular bone defects.Methods:Since February 2017, 10 cases of 3D-printed customized flanged cups were used in hip revision with severe acetabular bone defects, including 2 cases of Paprosky type IIIA and 8 cases of Paprosky type IIIB. There were 5 males and 5 females, mean age 73.6±8.1 yrs (range, 62-87 yrs), 5 left and 5 right cases. The preoperative thin-layer CT scan was preformed to reverse reconstruct digital pelvis. Five cases of one-piece flanged cups and 5 cases of decomposed flanged cups, including 3 cases of composite one-piece cups were designed by computer. The surgery was performed strictly according to the plan.Postoperative follow-up was performed to evaluate the Harris score. Operation time,intraoperative bleeding and other complications such as vascular and nerve injury, postoperative infection, and dislocation were counted. Pelvic X-ray was used to assess the height and horizontal position of the center of rotation and the stability of the prosthesis.Results:The surgical procedure was successful, with an average operative time of 147.9±48.3 min (range, 96-212 min) and an average intraoperative bleeding of 730.4±262.6 ml (range, 500-1 300 ml). The mean time of final follow-up was 40.8±18.7 months (range, 16-70 months) after surgery. At the last follow-up, the average Harris score was 83.80±6.73, with 4 cases excellent, 5 cases good, and 1 case fair. The excellent and good rate was 90%. The last Harris score was significantly higher than that before operation 28.60±8.40 ( t=16.84, P<0.001). The height of affected hip joint rotation center decreased from 46.24±7.74 mm before operation to 15.54±2.54 mm after operation with significant difference ( t=14.61, P<0.001). It was slightly higher than the opposite side (13.81±1.48 mm), which had no significant difference ( t=1.83, P=0.100). The horizontal distance of affected hip joint rotation center increased from 33.79±5.27 mm before operation to 40.53±4.50 mm after operation with significant difference ( t=3.62, P=0.006). It had no significant difference ( t=1.28, P=0.232) compared with the opposite side (38.54±3.46 mm). All incisions were healed in one stage without infection, vascular or nerve injury. During the following-up, all prostheses were in satisfied position without loosening, dislocation or screw breaks. Conclusion:Digitally assisted 3D-printed flanged cups can be used in hip revision with severe acetabular bone defect. It can not only improve hip joint function, but also restore the acetabular rotation center and the prosthesis stability, which can achieve good early and mid-term effect.

Ilizarov bone transport assisted by a 3D printed patient-specific guide plate for treatment of tibial bone defects / 中华创伤骨科杂志

Objective:To evaluate the efficacy of 3D printed patients-specific guide plates in assisting Ilizarov bone transport in the treatment of tibial bone defects.Methods:A retrospective study was conducted to analyze the clinical data of 24 patients with tibial bone defects who had been admitted to Institute of Trauma Orthopedics, The 80th Army Group Hospital of PLA from January 2018 to March 2022. There were 9 males and 15 females with an age of (49.8±6.5) years, and 4 upper tibial defects, 5 middle tibial defects, and 15 lower tibial defects. According to the methods of repairing bone defects, the patients were divided into 2 groups: a 3D printing group of 10 cases where a 3D printed patient-specific guide plate was used to assist Ilizarov bone transport in the treatment of tibial bone defects, and a traditional group of 14 cases where Ilizarov bone transport was performed in a traditional manner. The 2 groups were compared in terms of operation time, frequency of intraoperative fluoroscopy, axial angulation of the tibia at postoperation and the last follow-up, external fixation time (EFT) and external fixation index (EFI). At the last follow-up, healing of bone defects was evaluated according to the criteria of The Association for the Study and Application of the Method of Ilizarov (ASAMI), functional outcomes were evaluated according to the Paley criteria, and needle infection was recorded according to the Paley classification for complications.Results:There was no statistically significant difference in the preoperative general data between the 2 groups, indicating comparability ( P>0.05). All patients were followed up for (11.3±2.0) months on average after operation. The 3D printing group had significantly shorter operation time [(19.9±2.6) min] and significantly lower frequency of intraoperative fluoroscopy [(3.0±0.8) times] than the traditional group [(38.1±2.2) min and (8.9±1.3) times] (P<0.05), and had significantly better axial angulation of the tibia at postoperation and the last follow-up than the traditional group ( P<0.05). There was no significant difference in EFT or EFI between the 2 groups ( P>0.05), and the last follow-up revealed no significant difference either in bone healing, functional outcomes, or needle infection between the 2 groups ( P>0.05). Conclusion:In the treatment of tibial bone defects, compared with conventional Ilizarov bone transport, the Ilizarov bone transport assisted by a 3D printed patient-specific guide plate demonstrates advantages of shorter operation time, lower intraoperative fluoroscopy, and higher reduction accuracy.

Design of an anatomic plate of ulna coronoid process by 3D printing and computer software / 中华创伤骨科杂志

Objective:To design an anatomical plate of ulna coronoid process using 3D printing and computer model design software based on a collection of CT scanning data of the ulna coronoid process.Methods:The CT scans of the elbow joint with no obvious anatomic variation, no fracture, or no history of elbow operation were collected which had been taken at Trauma Center, The First Affiliated Hospital of Kunming Medical University from September 2017 to January 2022. There were 52 males and 50 females. RadiAnt DICOM Viewer and Mimics Medical 21.0 were used to visualize the CT data of the elbow joint of 102 volunteers. The software was used to measure the angle between the tip of the ulna coronoid process and the tuberosity of the ulna, the width at 1/2 height of the ulna coronoid process, the distance between the tip of the ulna coronoid process and the horizontal plane of the ulna tuberosity, and the safety angle for screw placement. After the values were measured, Siemens Ungraphics NX12.0 software was used to design the anatomical plate and the screw guide device of the ulna coronoid process. After the plate model was designed, a 1:1 actual plate model of the ulna coronoid process was produced by 3D printing. The actual plate model was placed onto an adult model of the ulna coronoid process and an adult cadaveric specimen of the ulna coronoid process to verify its matching degree. An in vitro operation was simulated using the plate model to verify its operability. Results:There were no significant differences between the left and right sides in the angle between the tip of the ulna coronoid process and the tuberosity of the ulna, the width at 1/2 height of the ulna coronoid process, the distance between the tip of the ulna coronoid process and the horizontal plane of the ulna tuberosity, or the safety angle for screw placement in either males or females ( P>0.05). There were no significant differences between males and females in the angle between the tip of the ulna coronoid process and the tuberosity of the ulna or in the safety angle for screw placement ( P>0.05). There were statistically significant differences between males and females in the width of 1/2 height of the ulna coronoid process and the distance between the tip of the ulna coronoid process and the horizontal plane of the ulna tuberosity ( P<0.05). However, the experiments on computer simulative adaptation and plate model simulative adaptation found that the anatomical plates of the ulna coronoid process designed on various parameters of males and females were exchangeable, leading to similarly good marching degrees and safe angles for screw placement. Conclusions:The anatomical plate of the ulna coronoid process designed in this study demonstrates a good fit and a safe angle for screw placement, basically achieving the goal expected to provide a basis for fabrication of a titanium alloy plate. In design of an anatomical plate of ulna coronoid process, it is not necessary to differentiate males from females or to differentiate the left side from the right one, because only a general plate can be used for both males and females and for both the left and the right sides.

Hemodynamic Effects of Banding Width on Pulmonary Artery / 医用生物力学

Objective To investigate the effects of banding width on hemodynamic characteristics of pulmonary artery (PA) by constructing pulmonary artery banding (PAB) models with different widths. Methods Based on clinical practice, with the same banding position and degree, computer-aided design (CAD) was utilized to reconstruct three-dimensional PAB models with different banding widths (2, 3, 4, 5 mm). Hemodynamic characteristics of the models with different banding widths, including pressure, streamlines, energy loss, energy efficiency and blood flow distribution ratio, were compared and analyzed through computational fluid dynamics (CFD). Results The pressure of PA decreased significantly, while the change of banding width had no significant effects on the pressure drop level at banding position. With the increase of banding width, the energy loss decreased, and the energy efficiency showed an upward trend. The blood flow of the left PA raised, and the ratio of blood flow distribution between the left PA and right PA increased, with the maximum reaching up to 2.28 : 1. Conclusions The increase of banding width can reduce the energy loss of PA and improve the energy efficiency of blood flow, but it will lead to the imbalance of blood flow distributions between the left and right lungs. Both the balance of blood flow distribution and the energy loss should be considered in choice for banding width of PAB. The virtual design of PAB surgery based on CAD and CFD will assist individualized banding width selection in future.

Application of 3D printing technology in the precise functional reconstruction of jaws / 口腔疾病防治

@#With the development of computer-aided surgery and rapid prototyping via 3D printing technology, digital surgery has rapidly advanced in clinical practice, especially in the field of oral and maxillofacial surgery. 3D printing technology has been applied to the functional restoration and reconstruction of the jawbone. Before surgery, a 3D digital model is constructed through software to plan the scope of the osteotomy, shape the bone graft and plan the placement of the implant. Additionally, 3D models of personalized surgical instrument guides are printed prior to surgery. With these 3D-printed models and guides, accurate excision of the jaw tumor, accurate placement of the grafted bone and precise placement of implants can be achieved during surgery. Postoperative evaluation of accuracy and function shows that 3D printing technology can aid in achieving the biomechanical goals of simultaneous implant placement in jaw reconstruction, and in combination with dental implant restoration, the technology can improve patients' postoperative occlusal and masticatory functions. Nevertheless, 3D printing technology still has limitations, such as time-consuming preparation before surgery. In the future, further development of 3D printing technology, optimization of surgical plans, and alternative biological materials are needed. Based on domestic and foreign literature and our research results, we have reviewed the process and clinical application prospects of jaw reconstruction via 3D printing technology to provide a reference for oral and maxillofacial surgeons.

Fracture strength and failure load of CAD/CAM fabricated endocrowns performed with different designs

Aim: Endocrown restorations are commonly used to rehabilitate endodontically treated posterior teeth and their use is well-founded in these cases. However, to date, there is little scientific evidence of their behavior in anterior teeth. The aim of this in vitro study was to evaluate the compressive strength of upper central incisors teeth, restored with glass-ceramic total crowns by the conventional anatomical core technique, and compare them to teeth restored with endocrowns with and without the presence of ferrule. Methods: Thirty teeth were randomly distributed into three groups: GE2 - endocrown group with 2 mm ferrule, GE0 - endocrown group without a ferrule, and GC - conventional crown with intraradicular post group. Crowns were cemented and teeth submitted to the 45o compression test until the fracture happened. Fractured specimens were analyzed to determine the fracture pattern. Descriptive analysis of the variables was performed and one-way analysis of variance was utilized to analyze the data for significant differences at p < 0.05. Results: The results of the control group (284.5 ± 201.05N) showed the highest fracture resistance value, followed by the 2mm group (274.54 ± 199.43N) and by the 0mm group (263.81 ± 80.05N). There was no statistically significant difference between all the groups (p = 0.964). Conclusions: The absence of a cervical enamel necklace favored a debonding of the pieces and endodontically treated anterior teeth could be restored with endocrown, which could be considered a conservative and viable treatment option

Sistema CAD/CAM en la confección de prótesis totales dentales / The CAD/CAM system in the fabrication of total dental prostheses

La técnica CAD/CAM es un sistema que ha facilitado los procesos de toma de impresiones totales e incorpora registros intraorales y requisitos apropiados para lograr bases protésicas adecuadas, lo cual permite óptimos resultados en clínica dental, como son el ahorro de tiempo y la comodidad para el especialista y el paciente, razones que llevan al profesional estomatológico a dar el paso hacia una odontología digital. El objetivo del estudio fue analizar el sistema CAD/CAM en la confección de prótesis totales dentales. La búsqueda se realizó en las bases de datos Google Scholar, Pubmed y Scopus, intentando responder a la pregunta orientadora: ¿Cuáles son los aspectos más significativos para el sistema CAD/CAM en la confección de prótesis totales dentales? Como resultados, se pudo interpretar que, consiguiendo registros tridimensionales producidos en un escáner, se proporciona una mejor adaptación de estructuras respecto a los métodos convencionales, por lo que induce estética y precisión, que son factores importantes en la odontología. Se concluyó que el sistema CAD/CAM disminuye el margen de error humano y conduce a mayores éxitos odontológicos, al brindar un mejor soporte para la toma decisiones y conseguir mejores resultados estéticos y funcionales en las prótesis totales de los pacientes(AU)

The CAD/CAM technique is a system that has facilitated the process of taking total impressions and incorporates intraoral records and appropriate requirements to achieve adequate prosthetic bases, which allows optimal results in the dental clinic, such as time savings and comfort for the specialist and the patient, reasons that lead the dental professional to take the step towards digital dentistry. The objective of the study was to analyze the CAD/CAM system in the fabrication of total dental prostheses. The search was carried out in Google Scholar, Pubmed and Scopus databases, trying to answer the guiding question: What are the most significant aspects for the CAD/CAM system in the manufacture of total dental prostheses? As results, it was possible to interpret that, by obtaining three-dimensional records produced in a scanner, it provides a better adaptation of structures compared to conventional methods, thus inducing esthetics and precision, which are important factors in dentistry. It was concluded that the CAD/CAM system reduces the margin of human error and leads to greater dental success by providing better support for decision making and achieving better esthetic and functional results in the total prostheses of patients(AU)