Nanotopography and oral bacterial adhesion on titanium surfaces: in vitro and in vivo studies

Abstract The present study aimed to evaluate the influence of titanium surface nanotopography on the initial bacterial adhesion process by in vivo and in vitro study models. Titanium disks were produced and characterized according to their surface topography: machined (Ti-M), microtopography (Ti-Micro), and nanotopography (Ti-Nano). For the in vivo study, 18 subjects wore oral acrylic splints containing 2 disks from each group for 24 h (n = 36). After this period, the disks were removed from the splints and evaluated by microbial culture method, scanning electron microscopy (SEM), and qPCR for quantification of Streptococcus oralis, Actinomyces naeslundii, Fusobacterium nucleatum, as well as total bacteria. For the in vitro study, adhesion tests were performed with the species S. oralis and A. naeslundii for 24 h. Data were compared by ANOVA, with Tukey's post-test. Regarding the in vivo study, both the total aerobic and total anaerobic bacteria counts were similar among groups (p > 0.05). In qPCR, there was no difference among groups of bacteria adhered to the disks (p > 0.05), except for A. naeslundii, which was found in lower proportions in the Ti-Nano group (p < 0.05). In the SEM analysis, the groups had a similar bacterial distribution, with a predominance of cocci and few bacilli. In the in vitro study, there was no difference in the adhesion profile for S. oralis and A. naeslundii after 24 h of biofilm formation (p > 0.05). Thus, we conclude that micro- and nanotopography do not affect bacterial adhesion, considering an initial period of biofilm formation.

In vitro study on cyclic fatigue resistance of three types of nickel titanium files in preparation for bending root canals / 口腔疾病防治

Objective@#The purpose of this study was to investigate the differences in the anti cyclic fatigue performance of Woride KS (WKS), Proteper Gold (PTG), and Hyflex CM (HCM) nickel titanium instruments with different tip diameters in curved root canal models, and to provide reference for the targeted selection of suitable nickel titanium instruments in clinical preparation of curved root canals.

Evaluation the scanning accuracy of Blue-Light laboratory scanners in complete edentulous Maxilla with multiple implants with titanium scan bodies / Evaluación de la precisión de escaneado de los escáneres de laboratorio de luz azul en maxilares desdentados completos con implantes múltiples con cuerpos de escaneado de titanio

Abstract To evaluate the accuracy of complete arch scanning with multiple implant titanium scan bodies using laboratory scanners. A master model of an edentulous maxillary arch with 6 implants was fabricated. Titanium scan bodies were inserted into the model. Three laboratory scanners were used: D2000 (3Shape), Vinyl High Resolution (Smart Optics), and inEos X5 (Dentsply Sirona). The master model was consecutively scanned ten times using dental laboratory scanners (LS) without detaching and repositioning the scan bodies. Linear and angular accuracy between adjacent implants was measured using inspection software (Control X, Geomagic). The accuracy of the complete arch scans was calculated. Implant regions were defined as; parallel (R1: #24-26 and #16-14), angled (R2: #22-24 and #14-12), angled to occlusal plane (R3: #12-22), and cross-arch (R4: #16-26). The effect of LS and implant region on accuracy was compared using two-Way ANOVA (α=0.05). Significant greater linear distortion was noted in R4 (61.2±17.9µm) compared to R1 (23.4±15.5µm) and R2 (26±17.7µm) (p<0.01). Greater linear distortions were noted in R4 with D2000 (0.07±0.016 degrees) and Vinyl High Resolution (0.067±0.02 degrees) than inEos X5 (0.032±0.021 degrees) (p>0.05). Greater mean linear precisions were noted in R1 (9±8µm) and R3 (9.3±8.3µm) than R4 (12.6±10.3µm) (p<0.05). The highest linear precision was noted in D2000 (7.2±7.6µm) (p<0.05). The angular precision of D2000 (0.02±0.015 degrees) was the highest (p<0.01). The angular precisión of R4 (0.036±0.018 degrees) was the lowest (p<0.01). This study revealed that the trueness was affected by the implant region and the precision was affected by both LS and implant region.

Resumen Evaluar la precisión del escaneado de la arcada completa con cuerpos de escaneado de titanio de múltiples implantes utilizando escáneres de laboratorio. Se fabricó un modelo maestro de una arcada maxilar edéntula con 6 implantes. Se insertaron cuerpos de escaneo de titanio en el modelo. Se utilizaron tres escáneres de laboratorio: D2000 (3Shape), Vinyl High Resolution (Smart Optics) e inEos X5 (Dentsply Sirona). El modelo maestro se escaneó consecutivamente diez veces usando escáneres de laboratorio dental (LS) sin separar y reposicionar los cuerpos de escaneo. La precisión lineal y angular entre implantes adyacentes se midió utilizando un software de inspección (Control X, Geomagic). Se calculó la precisión de los escaneos completos del arco. Las regiones del implante se definieron como; paralelo (R1: #24-26 y #16-14), angulado (R2: #22-24 y #14-12), angulado al plano oclusal (R3: #12-22) y cruzado (R4: #16-26). El efecto de LS y la región del implante en la precisión se comparó mediante ANOVA de dos vías (α=0,05). Se observó una distorsión lineal significativamente mayor en R4 (61,2±17,9µm) en comparación con R1 (23,4±15,5µm) y R2 (26 ±17,7µm) (p<0,01). Se observaron mayores distorsiones lineales en R4 con D2000 (0,07±0,016 grados) y vinilo de alta resolución (0,067±0,02 grados) que en inEos X5 (0,032±0,021 grados) (p>0,05). Se observaron precisiones lineales medias mayores en R1 (9±8µm) y R3 (9,3±8,3µm) que en R4 (12,6±10,3µm) (p<0,05). La mayor precisión lineal se observó en D2000 (7,2±7,6 µm) (p<0,05). La precisión angular de D2000 (0,02±0,015 grados) fue la más alta (p<0,01). La precisión angular de R4 (0,036±0,018 grados) fue la más baja (p<0,01). Este estudio reveló que la veracidad se vio afectada por la región del implante y la precisión se vio afectada tanto por LS como por la región del implante.

Comparación Placas de Titanio vs. Placas Reabsorbibles en Fracturas de Orbita: Revisión de literatura / Comparison of Titanium Plates vs. Resorbable Plates in Orbital Fractures: Literature Review

RESUMEN Introducción: Los tratamientos para fracturas de órbita se basan en la corrección del defecto de las lesiones orbitarias de tipo blow in y blow out (o de estallido), mediante diversas placas y mallas biocompatibles con el organismo, dándose una cicatrización de primera generación evitando un callo óseo y una fijación más rígida. Para el diagnóstico de este tipo de lesiones tenemos inflamación periorbitaria, enoftalmos, diplopía, equimosis, hemorragia subconjuntival. Existen diversos materiales reconstructivos siendo estos compuestos por distintas materias primas, como son los aloplásticos y autógenos; donde encontramos varios tipos como placas de titanio y las placas reabsorbibles siendo estas las más comunes y usadas actualmente, por su bajo estímulo a reabsorciones óseas y evitando efectos secundarios a largo plazo. Estas placas presentan diversos grados de ductilidad y resistencia. Se informó sobre varias complicaciones según el tipo de placas como es la cicatrización, las cirugías postquirúrgicas en caso de placas de titanio, etc. El objetivo de esta revisión es la evaluación de la eficacia las placas reabsorbibles versus placas de titanio en fracturas de órbita. Materiales y métodos: La investigación es de carácter documental, descriptivo y no experimental. En el cual se emplea una metodología de identificación e inclusión de artículos científicos tipo prisma. Resultados y conclusiones: Se verificaron las ventajas y desventajas tanto de las placas reabsorbibles como las de titanio siendo estas similares en la biocompatibilidad con el organismo humano, así como también varias diferencias como el soporte, fuerzas, resistencia de estas, concluyendo que es debatible el material ideal para tratar fracturas de órbita. Se seleccionaron artículos tomando en cuenta el título y objetivos; considerando estudios comparativos, revisiones sistemáticas, revisiones de literatura, los cuales comprendían criterios con respecto a fracturas de órbita y tratamientos quirúrgicos. La búsqueda arrojó 55 artículos en PubMed, 65 en Google, 4 en Scielo y 29 en Science direct, de los cuales se excluyeron libros, monografías, estudios experimentales, dando como resultado 21 artículos para el desarrollo de esta revisión bibliográfica. Y que fueron leídos y analizados en su totalidad, estudiando los objetivos, metodología y conclusión de cada uno de ellos para la posterior comparación.

ABSTRACT Introduction: Treatments for orbit fractures are based on the correction of the defect of blow in and blow out orbital injuries, by means of various plates and meshes biocompatible with the organism, giving a first-generation healing avoiding a bony callus and a more rigid fixation. For the diagnosis of this type of lesions we have periorbital inflammation, enophthalmos, diplopia, ecchymosis, subconjunctival hemorrhage. There are several reconstructive materials being these composed of different raw materials, such as alloplastic and autogenous, where we find several types such as titanium plates and resorbable plates being these the most common and currently used, for its low stimulus to bone resorption and avoiding long-term side effects. These plates have different degrees of ductility and resistance. Several complications have been reported depending on the type of plates, such as scarring, post-surgical surgeries in the case of titanium plates, etc. The objective of this review is to evaluate the efficacy of resorbable versus titanium plates in orbital fractures. Materials and methods: This research are a documentary, descriptive and non-experimental nature. A prism-type methodology of identification and inclusion of scientific articles was used. Results and conclusions: The advantages and disadvantages of both resorbable and titanium plates were verified, being these similar in biocompatibility with the human organism, as well as several differences such as support, forces, resistance of the same, concluding that it is debatable. The ideal material to treat orbital fractures. Articles were selected considering the title and objectives; considering comparative studies, systematic reviews, literature reviews, which included criteria regarding orbital fractures and surgical treatments. The search yielded 55 articles in PubMed, 65 in Google, 4 in Scielo and 29 in Science direct, from which books, monographs, experimental studies were excluded, resulting in 21 articles for the development of this bibliographic review. The 21 articles were read and analyzed in their entirety, studying the objectives, methodology and conclusion of each one of them for subsequent comparison.

CYCLIC AND TORSIONAL FATIGUE RESISTANCE OF THERMALLY TREATED ROTARY NiTiINSTRUMENTS WITH DIFFERENT DESIGNS

Aims: The aim was to evaluate the cyclic and torsional fatigue resistance among thermally treated NiTi rotary instruments with different design features.Materials and methods: Sixty instruments of three systems were used (n=20): TruNatomy 26.04 (TN 26.04), BassiLogic 25.05 (BL 25.05), and Flat File 25.04 (FF 25.04). The cyclic fatigue test (n=10) was performed to evaluate the time to fracture (s) and the number of cycles until failure (NCF). The torsion test was performed to evaluate the torque (N.cm) and maximum angular deflection until fracture (n=10). The fracture surface of each fragment was examined under a scanning electron microscope. The data were analyzed by Tukey's test (p<0.05).Results: BL 25.05 and FF 25.04 instruments had a higher number of cycles and time to fracture compared with TN 26.04 (p<0.05). TN 26.04 instruments showed lower torque to fracture.Conclusions: Based on the proposed objectives and the methodology used, TruNatomy 26.04 instruments present lower resistance to cyclic fatigue and torsional fatigue when compared to BassiLogic 25.05 and Flat File 25.04 instruments.

Comparative Assessment of Contact Osteogenesis at the Titanium Implant-Bone Junction in Male Rabbits with Dissimilar Femoral Defects / Evaluación Comparativa de la Osteogénesis de Contacto en la Unión entre el Hueso y el Implante de Titanio en Conejos Macho con Defectos Femorales Diferentes

SUMMARY: Traumatized bone tissue has the capacity to repair itself so that it eventually regains its almost original form, even in the case of artificially inserted implants. The process that stays at the base of the regeneration is represented by osteogenesis or remote osteogenesis. The major difference between the two types of bone formation is the location of the cement line, which is located on the surface of the implant for contact osteogenesis and on the surface of the bone defect for remote osteogenesis. The aim of the present study was to assess the contact osteogenesis in the case of inserted titanium screws in holes with diameters of 1.8 mm and 1 mm respectively. The obtained results show, in the case of the groove with 1.8 mm that the newly proliferated bone represents 73.85 % of the total area, while in the case of the groove with 1 mm in diameter the value of the newly proliferated bone is 26.15 %. In conclusion, the insertion of titanium screws by self-tapping into the hole smaller than the core of the screw is accompanied by bone proliferation by contact osteogenesis much more modest than in the case of insertion into the hole larger than the core of the screw.

El tejido óseo traumatizado tiene la capacidad de reparar en forma espontánea, de modo que eventualmente recupera su forma casi original, incluso en el caso de implantes insertados artificialmente. El proceso que queda en la base de la regeneración está representado por la osteogénesis u osteogénesis a distancia. La principal diferencia entre los dos tipos de formación ósea es la ubicación de la línea de cemento, que se encuentra en la superficie del implante para la osteogénesis de contacto y en la superficie del defecto óseo para la osteogénesis remota. El objetivo del presente estudio fue evaluar la osteogénesis de contacto en el caso de tornillos de titanio insertados en forámenes con diámetros de 1,8 mm y 1 mm respectivamente. Los resultados obtenidos muestran, en el caso del surco de 1,8 mm que el hueso neoproliferado representa el 73,85 % del área total, mientras que en el caso del surco de 1 mm de diámetro el valor del hueso neoproliferado es del 26,15 %. En conclusión, la inserción de tornillos de titanio por autorroscantes en el foramen menor que el núcleo del tornillo se acompaña de una proliferación ósea por osteogénesis de contacto mucho más modesta que en el caso de la inserción en el foramen mayor que el núcleo del tornillo.

UTILIZAÇÃO CLÍNICA DO TETRAFLUORETO DE TITÂNIO NA ODONTOLOGIA: UMA REVISÃO CRÍTICA / CLINICAL USE OF TITANIUM TETRAFLUORIDE IN DENTISTRY: A CRITICAL REVIEW

Objetivo: avaliar a eficácia preventiva e terapêutica do tetrafluoreto de titânio (TiF4) em ensaios clínicos randomizados (ECR) e não randomizados (N-ECR). Materiais e Métodos: estudos sobre a eficácia do tetrafluoreto de titânio em esmalte e dentina, testado em diferentes veículos e formulações, foram obtidos nas seguintes bases de dados: PubMed, Cochrane Library, Scopus, Web of Science, LILACS/BBO e EMBASE, sem limite de ano de publicação ou idioma. Resultados: seis estudos com abordagem preventiva e terapêutica do TiF4 sobre a superfície dentária foram incluídos. Destes, três ECR e três N-ECR. Por meio da tabulação e categorização dos artigos, notou-se que o TiF4 obteve efeito positivo na prevenção da cárie em três estudos; efeito nulo no tratamento de lesões cariosas em dois; e apenas um estudo apresentou efeito negativo no tratamento da erosão quando comparado aos outros compostos fluoretados. Conclusão: Embora haja estudos na literatura, com distintos delineamentos metodológicos comprovando a eficácia do TiF4, tanto na prevenção quanto no tratamento de lesões de cárie e erosivas, ainda é necessário que mais ensaios clínicos randomizados sejam realizados, com o intuito de validar a eficácia da utilização clínica deste composto fluoretado.

Objective: to analyze the preventive and therapeutic efficacy of titanium tetrafluoride (TiF4) in studies with a methodological design based on randomized clinical trials (RCT) and non-randomized (N-RCT). Materials and Methods: data on the behavior of titanium tetrafluoride in enamel and dentin, tested in several vehicles and formulations, were extracted in the following databases: PubMed, Cochrane Library, Scopus, Web of Science, LILACS/BBO and EMBASE, without limitation of publication year or language. Results: six studies were obtained with preventive and therapeutic approach of TiF4 on the dental surface. Three studies were RCT and three were N-RCT. Through tabulation and categorization of articles, it was noticed that TiF4 showed a positive effect in caries prevention in three studies; a null effect in caries treatment was observed in two; and only one study had a negative effect in erosion treatment when compared to the other fluoridated compounds. Conclusion: Although there are several studies in the literature, with different methodological designs, proving the efficacy of TiF4 both in prevention and in therapeutic treatments of caries and dental erosion, it is still necessary that more clinical controlled studies be conducted, in order to validate the clinical use efficacy of this fluoride compound.

STUDY ON THE EFFECT OF BRASS AND COPPER ELECTRODES DURING ELECTRIC DISCHARGE MACHINING OF INCONEL 718 USING NANO PARTICLES MIXED DIELECTRIC FLUID.

Electrical Discharge Machine (EDM) parameters have a significant influence on machining characteristic like material removal rate (MMR) and tool wear rate (TWR). Inconel 718, which is widely used in the Medical, Marine, Architectural and food processing industries, is used as a work material. The tool electrode materials used are brass and copper. Experiments are conducted using face centered central composite design to determine the effects of process parameters like current rate, pulse on time, pulse off time and concentration of titanium carbide nano particle in dielectric fiuid. Based upon the experimental outcomes, the effect of brass and copper electrodes during electric discharge machining of Inconel 718 using nano particles mixed dielectric fiuid was investigated.

ASSESSMENT OF TORSION RESISTANCE OF GLIDE PATH ROTARY INSTRUMENTS

NiTi endodontic instruments for glide path are the most susceptible to fractures inside the root canal, mainly as a result of high torsional stress. Objective: The present study investigated the resistance to torsion and angular deflection of instruments destined for the glide path: ProGlider #16.02; T-File #17.02 and the MK Life #16.02. Materials and methods: Thirty rotating NiTi glide path instruments (n=10) with 25mm lengths were selected. The torsion test was performed based on ISO 3630-01 (1992). Three millimeters from the tip of the instruments, it was attached to a small load cell by a lever arm connected to the torsion shaft. Torsional strength and angular deflection were evaluated. Fracture surfaces were examined by scanning electron microscopy with magnifications of 1000x and 5000x in the cross section, and 50x in the lateral section. Statistical analysis was performed using the Kruskal-Wallis H test, followed by the Down's post hoc test. Results: The ProGlider instrument showed greater torsional strength (p<0.05) compared to the T-File (p<0.05) and MK Life (p<0.05), respectively. However, the T-File showed greater angular deflection (p<0.05) than the other groups tested. Conclusion: It can be concluded that the ProGlider instrument presented greater torque for the fracture, while the T-File instrument presented greater angular deflection.

Inhibitory Effect of Gallium Nitrate against Staphylococcus aureus and Its Action on the Formation of Biofilms on Titanium Surfaces

Aims: This study aimed to investigate the effect of gallium nitrate [Ga(NO3)3], an inorganic antimicrobial agent, against the growth and biofilm formation of Staphylococcus aureus on the titanium surface. Study Design: This study is a laboratory investigation involving the determination of the inhibitory concentration (IC) of Ga(NO3) 3 against the planktonic strain of S. aureus and biofilm formation on titanium coupons. Place and Duration of Study: Sample: Center of Science and Technology for Sustainability (CCTS), Federal University of São Carlos, SP, Brazil, between March 2020 and March 2022. Methodology: The inhibitory concentration of gallium nitrate was determined in a 96-well microtiter plate in Muller Hinton broth. The potential of the antimicrobial agent to inhibit biofilm formation by S. aureus on titanium surfaces was evaluated by Scanning Electron Microscopy (SEM). The cytotoxicity potential of Ga(NO3)3 was determined on V79 cells. Results: The results showed that the susceptibility of gallium nitrate against S. aureus was 1.40 µM, while SEM images revealed that concentrations of 90 µM inhibited biofilm formation by S. aureus. Conclusion: This research has shown promising results regarding gallium nitrate's potential of inhibiting the growth of both planktonic and sessile S. aureus cells. In addition, coating titanium surfaces with Ga(NO3)3 would be an extra alternative to prevent implant-associated infections due to its non-toxicity to cells.

Regulación de la implantología dental en México / Regulation of dental implantology in Mexico

Introducción: los implantes dentales se han convertido en uno de los tratamientos odontológicos con mayor demanda en todo el mundo, no sólo por el nivel máximo de funcionalidad y de estética, sino también debido a su estabilidad, osteointegración y facilidad en su rehabilitación. Es incierto si los implantes dentales se encuentran normados formalmente en México, lo que motiva a la revisión del estado actual. Objetivo: evidenciar el estado actual de la legislación de la práctica de la implantología dental en México a través de una revisión en la literatura. Material y métodos: revisión de las legislaciones existentes en México para la aplicación de implantes dentales y su contraparte en el mundo a través de la evaluación de normas expedidas en América y Europa. Resultados: se contabilizó un total de 17 escuelas de implantes dentales que cuentan con el reconocimiento de la Secretaría de Educación Pública, de las cuales tres son públicas y 14 privadas. Se presentó una discrepancia en los planes de estudio que va de 16 a 36 meses. Las escuelas no contaron con un aval normativo. Las normas internacionales para control de calidad y aplicación de la tecnología en implantes se ubicaron en Canadá, Estados Unidos, España, Reino Unido y Francia. Conclusiones: contar con un antecedente normativo establecido por los países de primer mundo y ausente en México permite evidenciar la necesidad de implementar una Norma Oficial Mexicana que regule la fabricación, distribución y almacenamiento de los implantes dentales en México. A la vez, la revisión sugiere que la Secretaría de Educación Pública norme los créditos mínimos necesarios en las instituciones educativas reconocidas para la formación de recursos humanos que ejercen la implantología dental (AU)

Introduction: dental implants have become one of the dental treatments with the highest demand in the world, not only because of the highest level of functionality and aesthetics, but also because of their stability, osseointegration and ease of rehabilitation. It is uncertain if dental implants are formally regulated in Mexico, which motivates the review of the current status. Objective: to demonstrate the current state of the legislation for the practice of dental implantology in Mexico through a review of the literature. Material and methods: review of the existing legislation in Mexico, for the application of dental implants and its counterpart in the world, through the evaluation of standards issued in America and Europe. Results: a total of 17 dental implant schools that have the recognition of the Ministry of Public Education were counted, of which 3 are public and 14 private. There was a discrepancy in the study plans that ranged from 16 to 36 months. Schools will not have regulatory backing. The international standards for quality control and application of technology in implants were located in Canada, the United States, Spain, the United Kingdom and France. Conclusions: having a normative antecedent established by the countries of the first world and absent in Mexico, allows to demonstrate the need for the implementation of an Official Mexican Standard, which regulates the manufacture, distribution and storage of dental implants in Mexico. At the same time, the review suggests that the Ministry of Public Education regulate the minimum necessary credits in recognized educational institutions, for the training of human resources that practice dental implantology (AU)

Influence of temperature on the torsional properties of two thermally treated NiTi rotary instruments

Abstract This study aimed to evaluate the influence of temperature on torsional strength and angular deflection of two experimental NiTi rotary instruments manufactured from Blue and Gold thermal treatments and with identical cross-sections. A total of 40 experimental NiTi instruments 25.06 and with a triangular cross-section and manufactured from Blue and Gold thermal treatments were used (n=20). The torsional test was performed in the 3 mm from the tip of the instrument according to ISO 3630-1. The torsional test evaluated the torsional strength and angular deflection to failure at room temperature (21°C ± 1° C) and body temperature (36°C ±1°C). The fractured surface of each fragment was observed by using scanning electron microscopy (SEM). Data were analyzed using an unpaired t test for inter and intra-group comparison and the level of significance was set at 5%. The results showed that the body temperature did not affect the torsional strength and angular deflection of the instruments when compared with room temperature (P>0.05). However, at body temperature, the Blue NiTi instruments presented significantly lower angular deflection in comparison with Gold NiTi instruments (P<0.05). There was no significant difference regarding the torsional strength of the instruments at body temperature (P>0.05). The temperature did not affect the torsional strength of the instruments manufactured from Blue and Gold technology. However, the Blue NiTi instruments presented significantly lower angular deflection than Gold instruments at 36°C temperature.

Resumo O objetivo deste estudo foi avaliar a influência da temperatura nas propriedades de torção (resistência à torção e deflexão angular) de dois instrumentos rotatórios experimentais de NiTi fabricados com secção triangu.ar e tratamentos térmicos Blue e Gold. Quarenta instrumentos experimentais de NiTi 25.06 com tratamento térmico Blue e Gold foram usados (n= 20). Foi avaliada a resistência torcional e a deflexão angular até a fratura na temperatura ambiente (21°C ± 1°C) e corporal (36°C ± 1°C). O teste torcional foi realizado nos 3 mm da ponta dos instrumentos de acordo com a ISO 3630-1. A superfície fraturada de cada instrumento foi observada pelo microscópio eletrônico de varredura (MEV). Os dados foram analisados por meio do teste t não pareado para a comparação inter e intragrupos e o nível de significância à 5%. Os resultados demonstraram que a temperatura corporal não afetou a resistência a torção e deflexão angular quando comparada com a temperatura ambiente (P>0.05). No entanto, na temperatura de 36°C o instrumento com tratamento térmico Blue apresentou menor deflexão angular quando comparado com o Gold (P<0.05). Não houve diferença significante entre os dois instrumentos em relação a resistência à torção. A temperatura corporal não modificou a resistência torcional dos instrumentos fabricados com tecnologia Blue e Gold. No entanto, os instrumentos com NiTi Blue apresentaram menor deflexão angular do que o Gold a 36°C.

Effects of Fretting Stimulation Amplitude on Bone Growth and Micro-Injury at the Interface Between Bone Tissues and TitaniuBead Coating / 医用生物力学

Objective To improve the performance of artificial joint at biological fixed interface by frettingmechanical stimulation. Methods Taking the bonding sample of active rat bone tissues and inactive titanium bead coating as the research object, by using the self-developed fretting mechanical stimulation test device, the effects of mechanical stimulation with different tangential fretting amplitudes on growth promotion and micro-injury of bone tissues at fixed interface were explored, and the mechanism of growth promotion and micro-injury of bonetissues on the surface of titanium bead coating under fretting stimulation was revealed. Results The mechanical stimulation group with 40 μm fretting amplitude showed the maximum interface bonding force between bone tissues and titanium bead coating. The tangential fraction force-displacement curves changed from elliptic shape to linear shape, and the bonding interface was in adhesion area, which was difficult to become loose. The bone tissues had the most complete structure, and the number of tissue cells adhering and growing on the surface of titanium bead coating was the largest, as well as the distribution range was the widest. With the increase of fretting amplitude, the promoting effect of fretting stimulation on bone growth weakened, the bonding strength between bone tissues and titanium bead coating interface gradually decreased, the internal cavity area increased, the number and proliferation activity of tissue cells decreased to varying degrees as well. Conclusions Fretting stimulation with different amplitudes can promote the growth of bone tissue and cause micro-injury at the same time, and the optimal fretting amplitude is 40 μm.

Effects of titanium dioxide nanoparticles on circRNA expression profiles in human hepatocellular carcinoma cells HepG2 / 北京大学学报(医学版)

OBJECTIVE@#To investigate the effect of titanium dioxide nanoparticles (TiO2 NPs) on the expression profile of circular ribonucleic acid (circRNA) in human hepatocytes through in vitro cell experiments, and to attempt to understand the potential mechanism of hepatotoxicity through bioinformatics analysis.@*METHODS@#TiO2 NPs were characterized from the aspects of particle size, shape and agglomeration state. The cell counting kit-8 (CCK8) was used to detect the cytotoxicity of TiO2 NPs against human hepatocellular carcinoma cells (HepG2) after exposure to 0, 1.56, 3.13, 6.25, 12.5, 25, 50, 100, and 200 mg/L TiO2 NPs for 24 h or 48 h. The cells were treated at doses of 0 mg/L TiO2 NPs (control group) and 100 mg/L TiO2 NPs (treatment group), and collected after exposure for 48 h, and then RNA from the extracted cell samples was collected and sequenced. The differential circRNAs between the control and the TiO2 NPs treatment groups were screened, and then the enrichment pathway of the differential circRNA target gene was analyzed by multivariate statistics. According to the sequencing results, significantly altered genes and important genes in the significant enrichment pathways were screened, and real-time reverse transcription-polymerase chain reaction (real-time RT-PCR) was performed to verify the results.@*RESULTS@#TiO2 NPs were spherical anatase with a hydrated particle size of (323.50±85.44) nm and a Zeta potential of (-21.00±0.72) mV in a serum-free medium. The results of the CCK8 cytotoxicity assay showed that with the increase of TiO2 NPs concentration, cell viability gradually decreased. A total of 11 478 circRNAs were found by RNA sequencing. Compared with the control groups, TiO2 NPs treatment groups (100 mg/L) had a total of 89 differential circRNAs, of which 59 were up-regulated and 30 were down-regulated. Analysis of the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway showed that the targeted genes of differential circRNAs were mainly enriched in fatty acid degradation, Fanconi anemia pathway, and fatty acid metabolism. The expression levels of circRNA.6730, circRNA.3650 and circRNA.4321 were significantly different between the TiO2 NPs treatment group and the control group, which were consistent with the sequencing results.@*CONCLUSION@#TiO2 NPs can induce changes in circRNA expression profile, and epigenetics may play an important role in the mechanism of hepatotoxicity.

Angiogenic property of cobalt and calcium-phosphorus doped coating on titanium surfaces in vitro / 口腔疾病防治

Objective@# To investigate the effect of cobalt (Co) and calcium-phosphate (Ca/P) doped coating on titanium surfaces and their angiogenic effect.@*Methods @# Microarc oxidation (MAO) was used to prepare Co-Ca/P-doped and Co-doped coatings. Titanium (Ti) sheet without MAO treatment was used as control. Scanning electron microscopy (SEM) was used to observe the surface micromorphology of the coatings. Energy dispersive spectrometry (EDS) was also applied to detect the doped chemicals and their contents. Standard soaking solutions of these coatings were prepared using an endothelial cell medium (ECM) solution for subsequent angiogenesis experiments. Human umbilical vein endothelial cells (HUVECs) were cultured on Matrigel with ECM soaking solutions for 4 h and 8 h. The microvessels were observed under a microscope, and the number of microtubules and their interconnecting nodes were analyzed with Image J software. @*Results@# Co doped and Co-Ca/P-doped coatings were successfully prepared by MAO, which was demonstrated by both SEM observation and EDS analysis. SEM observation showed that irregular crystals of the above chemicals were present on both Co and Co-Ca/P-doped coatings, commonly with a diameter <2 μm. However, more crystals were observed on the Co-Ca/P coatings than on the Co coating, and the distribution of the crystals was more homogenous on the Co-Ca/P coatings. However, only polishing scratches were observed on the Ti sample surface. EDS analysis indicated that in contrast to only Co in the Co coating, Co, Ca and P were doped within the Co-Ca/P coating, and none of the three elements were observed on the Ti plate surface. The number of vascular rings and nodes formed by HUVECs in the extract of the Co-Ca/P group was significantly higher than that of the Co group (P<0.05), and the angiogenic effect of these two components was significantly better than that of the Ti group (P<0.05). @*Conclusion@#The Co-Ca/P coating exhibits good angiogenic properties in vitro and is valuable for the development of new titanium implants with high surface bioactivity.

Correction of hemifacial microsomia using preformed titanium mesh combined with contralateral mandibular angle bone graft with CAD/CAM assistance / 口腔医学

@#Objective To explore the indications and clinical effects of simultaneous mandibular angleplasty on the unaffected side, performed using preformed titanium mesh combined with mandibular angle bone graft, for the treatment of hemifacial microsomia (HFM). Methods The study group included 11 patients between 2013 and 2021 with HFM who underwent simultaneous mandibular angle reduction of the unaffected side and augmentation of the affected side using resected bone scaffolds within the titanium mesh. A series of mandibular linear measurements such as ramus height(RH)and mandibular body length(BL), angular measurements, and asymmetry index combined with clinical photographs and postoperative complications were used to assess the therapeutic effect. Results Postoperatively, all patients were satisfied. Significant improvement in mandibular contour was shown, with no obvious complications. Postoperative data, such as BL and angular measurements, showed no statistically significant differences(P>0.05) between the affected and unaffected sides with improvement in symmetry, except for RH(P<0.05). The preoperative and postoperative asymmetry index were (17.11±4.56)% and (4.81±1.73)%, respectively, with significant improvement(P=0.002). Conclusion This approach provides satisfactory results and significantly improves facial asymmetries for unilateral HFM with hypertrophy of the contralateral mandibular angle.

Research progress on surface modification of titanium implants by strontium ions / 口腔疾病防治

@#Traditional titanium implants do not completely meet the clinical requirements because they are bioinert. The surface of titanium implants, modified by strontium ions, can enhance osseointegration and reduce peri-implantitis. In this paper, the biological properties of titanium implant surfaces modified by strontium ions were reviewed. Strontium ions can be coated on the implant surface by hydrothermal treatment, electrochemical deposition, phosphate chemical conversion, flame-spraying, supramolecular self-assembly, magnetron sputtering, laser deposition and alkali etching. Implant surfaces modified by strontium ions can not only promote osteogenesis and early osseointegration but also inhibit bacterial growth and reduce postoperative infections. Even better osseointegration and antibacterial effects can be achieved when strontium ions are incorporated with other elements, such as silver, zinc, gallium, and calcium. However, most of the studies on the use of strontium ion-modified titanium implants are animal experiments and in vitro experiments, and the observation time is short compared with the actual service life of the implants. Thus, the conclusions obtained may be different from the actual clinical application, and the long-term effects need to be studied. In addition, the osteogenic effects of various modification methods also need to be compared. Future research can focus on the following points: ① to find efficient modification methods that can be widely used in the clinic; ②to study how to control the concentration of strontium ions near the implant to exert their biological function and reduce their toxic side effects; and ③ to conduct long-term follow-up clinical trials to observe their osteogenic and antibacterial effects.

Surgical technique and effectiveness of titanium elastic nail assisted retrograde channel screw implantation in superior pubic branch / 中国修复重建外科杂志

OBJECTIVE@#To investigate the surgical technique and effectiveness of titanium elastic nail (TEN) assisted retrograde channel screw implantation of superior pubic branch.@*METHODS@#The clinical data of 31 patients with pelvic or acetabular fractures treated with retrograde channel screw implantation in superior pubic branch between January 2021 and April 2022 were retrospectively analyzed. Among them, 16 cases were implanted with assistance of TEN (study group) and 15 cases were implanted under the guidance of C-arm X-ray machine (control group). There was no significant difference in gender, age, cause of injury, Tile classification of pelvic fracture, Judet-Letournal classification of acetabular fracture, and time from injury to operation between the two groups ( P>0.05). The operation time, fluoroscopy times, and intraoperative blood loss of each superior pubic branch retrograde channel screw were recorded during operation. X-ray films and three-dimensional CT were reexamined after operation, the quality of fracture reduction was evaluated by Matta score standard, and the position of channel screw was evaluated by screw position classification standard. The fracture healing time was recorded during the follow-up, and the postoperative functional recovery was evaluated by Merle D'Aubigne Postel score system at last follow-up.@*RESULTS@#Nineteen and 20 retrograde channel screws of superior pubic branch were implanted in the study group and the control group, respectively. The operation time, fluoroscopy times, and intraoperative blood loss of each screw in the study group were significantly less than those in the control group ( P<0.05). According to the postoperative X-ray films and three-dimensional CT, none of the 19 screws in the study group penetrated out of the cortical bone or into the joint, and the excellent and good rate was 100% (19/19); in the control group, there were 4 screws of cortical bone penetration, and the excellent and good rate was 80% (16/20); the difference between the two groups was significant ( P<0.05). Matta score standard was used to evaluate the quality of fracture reduction, there was no patient in the two groups with poor reduction results, and the difference was not significant between the two groups ( P>0.05). The incisions of the two groups healed by first intention, and there was no complication such as incision infection, skin margin necrosis, and deep infection. All patients were followed up 8-22 months, with an average of 14.7 months. There was no significant difference in healing time between the two groups ( P>0.05). At last follow-up, the difference in functional recovery evaluated by the Merle D'Aubigne Postel scoring system between the two groups was not significant ( P>0.05).@*CONCLUSION@#TEN assisted implantation technique can significantly shorten the operation time of retrograde channel screw implantation of superior pubic branch, reduce the times of fluoroscopy, and have less intraoperative blood loss and accurate screw implantation, which provides a new safe and reliable method for minimally invasive treatment of pelvic and acetabular fractures.

Dosimetric Impact of Titanium Alloy Implant in Spinal IMRT Plan / 中国医疗器械杂志

The purpose of this study is to establish and apply a correction method for titanium alloy implant in spinal IMRT plan, a corrected CT-density table was revised from normal CT-density table to include the density of titanium alloy implant. Dose distribution after and before correction were calculated and compared to evaluate the dose deviation. Plans were also copied to a spinal cancer simulation phantom. A titanium alloy fixation system for spine was implanted in this phantom. Plans were recalculated and compared with the measurement result. The result of this study shows that the max dose of spinal cord showed significant difference after correction, and the deviation between calculation results and measurement results was reduced after correction. The method for expanding the range CT-density table, which means that the density of titanium alloy was included, can reduce the error in calculation.

3D-printed vertebral body in anterior spinal reconstruction after total spondylectomy for patients with cervical chordoma / 北京大学学报(医学版)

OBJECTIVE@#To investigate whether 3D-printed artificial vertebral body can reduce prosthesis subsidence rate for patients with cervical chordomas, through comparing the rates of prosthesis subsidence between 3D printing artificial vertebral body and titanium mesh for anterior spinal reconstruction after total spondylectomy.@*METHODS@#This was a retrospective analysis of patients who underwent surgical treatment for cervical chordoma at our hospital from March 2005 to September 2019. There were nine patients in the group of 3D artificial vertebral body (3D group), and 15 patients in the group of titanium mesh cage (Mesh group). The patients' characteristics and treatment data were extracted from the medical records, including age, gender, CT hounsfield unit of cervical vertebra and surgical information, such as the surgical segments, time and blood loss of surgery, frequency and degree of prosthesis subsidence after surgery. Radiographic observations of prosthesis subsidence during the follow-up, including X-rays, CT, and magnetic resonance imaging were also collected. SPSS 22.0 was used to analysis the data.@*RESULTS@#There was no significant difference between the two groups in gender, age, CT hounsfield unit, surgical segments, time of surgery, blood loss of posterior surgery and total blood loss. Blood loss of anterior surgery was 700 (300, 825) mL in 3D group and 1 500 (750, 2 800) mL in Mesh group (P < 0.05). The prosthesis subsidence during the follow-up, 3 months after surgery, there was significant difference between the two groups in mild prosthesis subsidence (P < 0.05). The vertebral height of the 3D group decreased less than 1 mm in eight cases (no prosthesis subsidence) and more than 1 mm in one case (mild prosthesis subsidence). The vertebral height of the Mesh group decreased less than 1 mm in five cases (no prosthesis subsidence), and more than 1 mm in eight cases (mild prosthesis subsidence). Two patients did not have X-rays in 3 months after surgery. There was a statistically significant difference between the two groups in the prosthesis subsidence rate at the end of 12 months (P < 0.01). The vertebral height of eight cases in the 3D group decreased less than 1 mm (no prosthesis subsidence) and one case more than 3 mm (severe prosthesis subsidence). Four of the 15 cases in the Mesh group decreased less than 1 mm (no prosthesis subsidence), two cases more than 1 mm (mild prosthesis subsidence), and nine cases more than 3 mm (severe prosthesis subsidence). There was a statistically significant difference between the two groups in the prosthesis subsidence rate at the end of 24 months (P < 0.01). The vertebral height of seven cases in the 3D group decreased less than 1 mm (no prosthesis subsidence), one case more than 3 mm (severe prosthesis subsidence), and one case died with tumor. One case in the Mesh group decreased less than 1 mm (no prosthesis subsidence), one case more than 1 mm (mild prosthesis subsidence), 11 case more than 3 mm (severe prosthesis subsidence), one case died with tumor and one lost the follow-up. Moreover, at the end of 12 months and 24 months, there was significant difference between the two groups in severe prosthesis subsidence rate (P < 0.01).@*CONCLUSION@#3D-printed artificial vertebral body for anterior spinal reconstruction after total spondylectomy for patients with cervical chordoma can provide reliable spinal stability, and reduce the incidence of prosthesis subsidence after 2-year follow-up.