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.

Influence of antimicrobial peptide biofunctionalized TiO2 nanotubes on the biological behavior of human keratinocytes and its antibacterial effect / 中华口腔医学杂志

Objective: To fabricate TiO2 nanotube material functionalized by antimicrobial peptide LL-37, and to explore its effects on biological behaviors such as adhesion and migration of human keratinocytes (HaCaT) and its antibacterial properties. Methods: The TiO2 nanotube array (NT) was constructed on the surface of polished titanium (PT) by anodization, and the antimicrobial peptide LL-37 was loaded on the surface of TiO2 nanotube (LL-37/NT) by physical adsorption. Three samples were selected by simple random sampling in each group. Surface morphology, roughness, hydrophilicity and release characteristics of LL-37 of the samples were analyzed with a field emission scanning electron microscope, an atomic force microscope, a contact angle measuring device and a microplate absorbance reader. HaCaT cells were respectively cultured on the surface of three groups of titanium samples. Each group had 3 replicates. The morphology of cell was observed by field emission scanning electron microscope. The number of cell adhesion was observed by cellular immunofluorescence staining. Cell counting kit-8 (CCK-8) assay was used to detect cell proliferation. Wound scratch assay was used to observe the migration of HaCaT. The above experiments were used to evaluate the effect of each group on the biological behavior of HaCaT cells. To evaluate their antibacterial effects, Porphyromonas gingivalis (Pg) was respectively inoculated on the surface of three groups of titanium samples. Each group had 3 replicates. The morphology of bacteria was observed by field emission scanning electron microscope. Bacterial viability was determined by live/dead bacterial staining. Results: A uniform array of nanotubes could be seen on the surface of titanium samples in LL-37/NT group, and the top of the tube was covered with granular LL-37. Compared with PT group [the roughness was (2.30±0.18) nm, the contact angle was 71.8°±1.7°], the roughness [(20.40±3.10) and (19.10±4.11) nm] and hydrophilicity (the contact angles were 22.4°±3.1° and 25.3°±2.2°, respectively) of titanium samples increased in NT and LL-37/NT group (P<0.001). The results of in vitro release test showed that the release of antimicrobial peptide LL-37 was characterized by early sudden release (1-4 h) and long-term (1-7 d) slow release. With the immunofluorescence, more cell attachment was found on NT and LL-37/NT than that on PT at the first 0.5 and 2.0 h of culture (P<0.05). The results of CCK-8 showed that there was no significant difference in the proliferation of cells among groups at 1, 3 and 5 days after culture. Wound scratch assay showed that compared with PT and NT group, the cell moved fastest on the surface of titanium samples in LL-37/NT group at 24 h of culture [(96.4±4.9)%] (F=35.55, P<0.001). A monolayer cells could be formed and filled with the scratch in 24 h at LL-37/NT group. The results of bacterial test in vitro showed that compared with the PT group, the bacterial morphology in the NT and LL-37/NT groups was significantly wrinkled, and obvious bacterial rupture could be seen on the surface of titanium samples in LL-37/NT group. The results of bacteria staining showed that the green fluorescence intensity of titanium samples in LL-37/NT group was the lowest in all groups (F=66.54,P<0.001). Conclusions: LL-37/NT is beneficial to the adhesion and migration of HaCaT cells and has excellent antibacterial properties, this provides a new strategy for the optimal design of implant neck materials.

The influence of haematogenous bone marrow on the early osseointegration of a titanium implant which penetrates the endosteum / La influencia de la médula ósea hematógena en la osteointegración temprana de un implante de titanio que penetra en el endostio

SUMMARY: The utility of metallic bio-medical implants in osseous or dental affections is irrefutable. The paper aims to test the tolerance of the bone marrow to titanium implants. Titanium implants were inserted in the femur of 11-months old rabbits. The implants penetrated the endosteum, half of their length getting into the haematogenous bone marrow. Seven days after the insertion we collected bone fragments containing the implant. The CT exam revealed a significant decrease in the density of the bone at the interface with the implant and a more discrete one aloof from the insertion area. The histologic exam after 7 days revealed osseous reparatory processes only in the endosteal area from where it expanded on the surface of the implant which was inside the marrow. The presence and intensity of the osseous reparatory processes after only seven days post-implant demonstrates that the marrow actively participates in bone regeneration and implants osseointegration.

RESUMEN: La utilidad de los implantes biomédicos metálicos en afecciones óseas o dentales es irrefutable. El documento tiene como objetivo probar la tolerancia de la médula ósea a los implantes de titanio. Se insertaron implantes de titanio en el fémur de conejos de 11 meses. Los implantes penetraron en el endostio y la mitad de su longitud penetró en la médula ósea hematógena. Siete días después de la inserción, recolectamos fragmentos de hueso que contenían el implante. El examen de TC reveló una disminución significativa en la densidad del hueso en la interfaz con el implante y una más discreta alejada del área de inserción. El examen histológico a los 7 días reveló procesos de reparación ósea solo en el área endóstica desde donde se expandió en la superficie del implante que estaba dentro de la médula. La presencia e intensidad de los procesos de reparación ósea después de solo siete días del implante demuestra que la médula ósea participa activamente en la regeneración ósea y en la osteointegración de los implantes.

Evolution and development: engine-driven endodontic rotary nickel-titanium instruments / 国际口腔科学杂志·英文版

Various engine-driven NiTi endodontic files have been indispensable and efficient tools in cleaning and shaping of root canals for practitioners. In this review, we introduce the relative terms and conceptions of NiTi file, including crystal phase composition, the design of the cutting part, types of separation. This review also analysis the main improvement and evolution of different generations of engine-driven nickel-titanium instruments in the past 20 years in the geometric design, manufacturing surface treatment such as electropolishing, thermal treatment, metallurgy. And the variety of motion modes of NiTi files to improve resistance to torsional failure were also discussed. Continuous advancements by the designers, provide better balance between shaping efficiency and resistance to of NiTi systems. In clinical practice an appropriate system should be selected based on the anatomy of the root canal, instrument characteristics, and operators' experience.

Cyclic Fatigue Resistance and Surface Roughness of Rotary NiTi Instruments after Simulated Clinical Use in Curved Root Canals - An Atomic Force Microscopy Study

Abstract Objective: To examine the cyclic fatigue resistance and surface topography of TruNatomy and ProTaper Gold nickel-titanium rotary files and evaluate the presence of alterations to surface topography following instrumentation in simulated curved canals. Material and Methods: Twenty-four nickel-titanium instruments, twelve each of TN and PTG file systems, were evaluated for cyclic fatigue resistance. The rotary files were rotated in a simulated root canal with standardized diameter, angle of curvature, and radius of curvature in a custom-made cyclic fatigue testing device until the instrument fracture occurred. The time to fracture for each instrument was recorded with a stopwatch; in seconds in each group. Fractured instruments were subjected to atomic force microscopy analysis measuring the average roughness and the root mean square values to investigate surface features of endodontic files. Mean values and standard deviation were calculated. Data were analyzed using the Mann-Whitney U test. Results: Time to fracture was marginally higher in PTG instruments than in the TN file systems. PTG files exhibited higher surface roughness when compared with TN files (p<0.05). Conclusion: TN file system had a higher cyclic fatigue resistance than PTG. Cyclic fatigue causing file breakage did affect the surface topography of the files. PTG files showed a higher surface porosity value than the TN files (AU).

Enhanced osseointegration of porous titanium scaffold implanted with preload: an experiment study in rabbits / Osteointegración mejorada de malla de titanio poroso implantada con precarga: un estudio experimental en conejos

Porous titanium alloy scaffold was widely used in treating bone defect caused by traumatic injury and osteomyelitis, which was incapable of self-healing. The implantation of scaffold produced stress shielding thereby forming osteolysis. The objective of this study was to analysis trabecular morphological features of osseointegrated bone. 14 New Zealand rabbits were divided into two groups, surgery group and healthy control group. 7 rabbits in surgery group were selected to perform 3D printed porous titanium alloy scaffold implantation surgery with preload at the defect of femoral condyle for osseointegration. The other 7 rabbits in control group were feed free. After 90 days healing, femoral condyles were extracted to perform micro-CT scanning with hydroxyapatite calibration phantom. Mean bone mineral density (BMD), bone volume fraction (BV/TV), BS/TV (bone surface area ratio), Tb.Th (thickness of trabeculae), Tb.N (number of trabeculae), Tb.Sp (trabecular separation) and DA (degree of anisotropy) were calculated from micro-CT images. The results revealed that osseointegration inside and at the surface of scaffolds worked well from grey values of micro-CT images. After 12 weeks healing, mean bone mineral densities (BMD) in surgery group and healthy control group were calculated as 800±20mg/cm3 and 980±90mg/cm3, respectively. This revealed that the strength of trabeculae in surgery group might lower than that in the healthy group. Trabecular morphological parameters test showed that trabecular morphological parameters at the surface of scaffolds in the surgery group deteriorated significantly. It was found from micro-CT images that ingrowth bone was filled with pores of scaffold. Overall, the effect of osseointegration was promoted through the change of mechanical micro-environment in the scaffold region. Overall, preload could improve osseointegration effect in the long-term after surgery. However, the trabecular morphology in the surgery group was deteriorated, which might bring secondary fracture risk again.

La malla de aleación de titanio poroso se usó ampliamente en el tratamiento de defectos óseos causados por lesiones traumáticas y osteomielitis. El implante de la malla generó una protección contra el estrés, formando así osteolisis. El objetivo de este estudio fue analizar las características morfológicas trabeculares del hueso osteointegrado. Se dividieron 14 conejos (Neozelandeses) en dos grupos, grupo cirugía y grupo control saludable. Se seleccionaron 7 conejos en el grupo de cirugía para realizar una implantación de mallas de aleación de titanio poroso, impresas en 3D con precarga en el defecto del cóndilo femoral para la osteointegración. Los 7 conejos restantes del grupo control se mantuvieron sin alimentación. Después de 90 días de curación, se extrajeron los cóndilos femorales para realizar una exploración por micro-CT con un espectro de calibración de hidroxiapatita. Se calcularon a partir de imágenes de micro-CTDensidad mineral ósea media (DMO), fracción de volumen óseo (BV / TV), BS / TV (relación de área de superficie ósea), Tb.Th (espesor de trabéculas), Tb.N (número de trabéculas), Tb.Sp (trabecular separación) y DA (grado de anisotropía). Los resultados revelaron que la osteointegración dentro y en la superficie de los andamios funcionó bien a partir de los valores grises de las imágenes de micro-CT. Después de 12 semanas de curación, las densidades medias de minerales óseos (DMO) en el grupo cirugía y en el grupo control sano se calcularon como 800 ± 20 mg/cm3 y 980 ± 90 mg/cm3, respectivamente. Esto reveló que la fuerza de las trabéculas en el grupo de cirugía podría ser menor que la del grupo sano. La prueba de parámetros morfológicos trabeculares mostró que en el grupo de cirugía, la superficie de las mallas, se deterioraron significativamente. Se descubrió a partir de imágenes de microCT que el hueso en crecimiento estaba lleno de poros de andamio. En general, el efecto de la osteointegración se promovió mediante el cambio del microambiente mecánico en la región de la malla. En general, la precarga podría mejorar el efecto de osteointegración a largo plazo después de la cirugía. Sin embargo, la morfología trabecular en el grupo de cirugía se deterioró, lo que podría traer un nuevo riesgo de fractura secundaria.

Effect of focal adhesion kinase inhibition on osteoblastic cells grown on titanium with different topographies

Abstract Objective The present study aimed to investigate the participation of focal adhesion kinases (FAK) in interactions between osteoblastic cells and titanium (Ti) surfaces with three different topographies, namely, untreated (US), microstructured (MS), and nanostructured (NS). Methodology Osteoblasts harvested from the calvarial bones of 3-day-old rats were cultured on US, MS and NS discs in the presence of PF-573228 (FAK inhibitor) to evaluate osteoblastic differentiation. After 24 h, we evaluated osteoblast morphology and vinculin expression, and on day 10, the following parameters: gene expression of osteoblastic markers and integrin signaling components, FAK protein expression and alkaline phosphatase (ALP) activity. A smooth surface, porosities at the microscale level, and nanocavities were observed in US, MS, and NS, respectively. Results FAK inhibition decreased the number of filopodia in cells grown on US and MS compared with that in NS. FAK inhibition decreased the gene expression of Alp, bone sialoprotein, osteocalcin, and ALP activity in cells grown on all evaluated surfaces. FAK inhibition did not affect the gene expression of Fak, integrin alpha 1 ( Itga1 ) and integrin beta 1 ( Itgb1 ) in cells grown on MS, increased the gene expression of Fak in cells grown on NS, and increased the gene expression of Itga1 and Itgb1 in cells grown on US and NS. Moreover, FAK protein expression decreased in cells cultured on US but increased in cells cultured on MS and NS after FAK inhibition; no difference in the expression of vinculin was observed among cells grown on all surfaces. Conclusions Our data demonstrate the relevance of FAK in the interactions between osteoblastic cells and Ti surfaces regardless of surface topography. Nanotopography positively regulated FAK expression and integrin signaling pathway components during osteoblast differentiation. In this context, the development of Ti surfaces with the ability to upregulate FAK activity could positively impact the process of implant osseointegration.

Extrusión Apical de Barro Dentinario e Irrigante Producidos por Dos Sistemas de Instrumentación de Níquel Titanio al Utilizar Irrigación Pasiva o Activa / Apical Extrusion of Dentin and Irrigant Smear Layer Produced by Two Nickel Titanium Instrumentation Systems when Using Passive or Active Irrigation

RESUMEN: El barro dentinario producido durante tratamiento endodóntico puede ser extruido hacia el tejido periradicular junto con el irrigante, produciendo inflamación y dolor postoperatorio. Comparar la cantidad de extrusión apical de barro dentinario e irrigante, producido durante la preparación químico-mecánica, por dos sistemas de instrumentación Rotatoria (Mtwo), y Reciprocante (Reciproc), complementado con irrigación pasiva o activa (Endoactivator). Cuarenta y ocho premolares (48) inferiores, fueron aleatoriamente distribuidos en cuatro grupos de estudio (n=12 dientes), (1) Rotatorio-pasiva, (2) Reciprocante-pasiva, (3) Rotatorio-activa y (4) Reciprocante-activa. Los conductos radiculares fueron instrumentados de acuerdo a las instrucciones del fabricante, e irrigados con hipoclorito de sodio al 5 %. El barro dentinario e irrigante extruido, fueron recolectados en tubos Eppendorf previamente pesados. Se calcularon los valores de extrusión de barro dentinario e irrigante para cada grupo. Los datos fueron analizados con el análisis de varianza ANOVA. En todos los grupos se produjo extrusión apical. No se encontraron diferencias estadísticamente significativas en la extrusión apical de barro dentinario, entre los grupos estudiados (P = 0,068), sin embargo, al analizar la extrusión de irrigantes, se evidenció diferencia estadísticamente significativa entre los grupos 1 y 4 (P< 0,05), entre los demás grupos no se observaron diferencias estadísticamente significativas. (P > 0,05). Bajo las condiciones de este estudio, los sistemas rotarios y reciprocante, extruyen sólido y líquido, siendo el sistema reciprocante el que produce mayor extrusión de líquido, tanto con irrigación activa como pasiva.

ABSTRACT: The smear layer produced during endodontic treatment can be extruded into the periradicular tissue together with the irrigant, producing inflammation and postoperative pain. The purpose of this in vitro study was to compare the amount of apical extrusion, produced during the endodontic preparations with two rotary instrumentation systems using passive and active irrigation. Forty-eight (48) mandibular premolars were randomly assigned to 4 groups (n = 12 teeth), (1) Rotatory - passive, (2) Reciprocating passive, (3) Rotatory-active, (4) Reciprocating- active. The root canals were instrumented according to the manufacturer's instructions and irrigated with 5 % sodium hypochlorite. Extruded debris and irrigant were collected in previously weighed Eppendorf tubes. The extrusion values were calculated for each group. The data were analyzed with the ANOVA analysis of variance. Results: Apical extrusion was produced in all groups. No statistically significant differences were found in the apical extrusion of smear layer, between the groups studied (P = 0.068), however, when analyzing the extrusion of irrigants, a statistically significant difference was evidenced between groups 1 and 4 (P <0.05). , among the other groups no statistically significant differences were observed. (P> 0.05). Under the conditions of this study, the reciprocating and rotary systems, extrude solid and liquid, being the reciprocating system the one that produces more extrusion of liquid, with both active and passive irrigation.

Cyclic fatigue resistance of novel Genius and Edgefile nickel-titanium reciprocating instruments

Abstract: This study aimed to assess the cyclic fatigue resistance of Genius and EdgeFile X1 reciprocating instruments compared with WaveOne Gold Primary. Twenty Genius (Ultradent) 25.04, 20 Genius 30.04, 20 EdgeFile X1 (EdgeEndo) and 20 WaveOne Gold Primary (Dentsply Maillefer) instruments were included in this study and tested in a static cyclic fatigue testing device, which has an artificial stainless steel canal with a 60° angle of curvature and a 5-mm radius of curvature. All instruments were operated in reciprocation mode until fracture occurred. The number of cycles to failure (NCF) was calculated and time to fracture (TF) was recorded in seconds using a digital chronometer. The mean and standard deviations of NCF and TF were calculated for each reciprocating system and the data were subjected to Kruskal-Wallis one-way analysis of variance and to Dunn's test (p < .05) using SigmaPlot software (Systat software, CA, USA). The fractured surfaces of five instruments from each brand were randomly examined and microphotographed by a low-vacuum environmental scanning electron microscopy - SEM (Tabletop Microscope TM3030, Hitachi, Japan) to confirm the cyclic fatigue fracture. EdgeFile exhibited the highest cyclic fatigue resistance, followed by both Genius files (p < .05). Within the limitations of this in vitro study, EdgeFile X1 instruments had significantly higher cyclic fatigue resistance than did Genius and WaveOne Gold Primary instruments. The cyclic fatigue resistance of both Genius files was higher than that of WaveOne Gold Primary.

Additive manufacturing of titanium alloy could modify the pathogenic microbial profile: an in vitro study

Abstract Additive manufacturing (AM) is an emerging process for biomaterials and medical devices. Direct Laser Metal Sintering (DLMS) is an AM technique used to fabricate Ti-6Al-4V implant materials with enhanced surface-related properties compared with wrought samples; thus, this technique could influence microbial adsorption and colonization. Therefore, this in vitro study was conducted to evaluate the impact of different implant production processes on microbial adhesion of periodontal pathogens. Titanium discs produced using two different processes—conventional and AM—were divided into three groups: conventional titanium discs with machined surface (G1), AM titanium discs with chemical treatment (G2) and AM titanium discs without chemical treatment (G3). Subgingival biofilm composed of 32 species was formed on the titanium discs, and positioned vertically in 96-well plates, for 7 days. The proportions of microbial complexes and the microbial profiles were analyzed using a DNA-DNA hybridization technique, and data were evaluated using Kruskal-Wallis and Dunnett tests (p < 0.05). Lower proportions of the red complex species were observed in the biofilm formed in G2 compared with that in G1 (p < 0.05). Moreover, the proportions of the microbial complexes were similar between G2 and G3 (p > 0.05). Compared with G1, G2 showed reduced levels of Porphyromonas gingvalis , Actinomyces gerencseriae, and Streptococcus intermedius , and increased levels of Parvimonas micra , Actinomyces odontolyticus, and Eikenella corrodens (p < 0.05). The microbial profile of G3 did not differ from G1 and G2 (p > 0.05). The results of this in vitro study showed that titanium discs produced via AM could alter the microbial profile of the biofilm formed around them. Further clinical studies should be conducted to confirm these findings.

Effect of stem cells combined with a polymer/ceramic membrane on osteoporotic bone repair

Abstract Cell therapy associated with guided bone regeneration (GBR) can be used to treat bone defects under challenging conditions such as osteoporosis. This study aimed to evaluate the effect of mesenchymal stem cells (MSCs) in combination with a poly(vinylidene-trifluoroethylene)/barium titanate (PVDF-TrFE/BT) membrane on bone repair in osteoporotic rats. Osteoporosis was induced in female rats by bilateral removal of the ovaries (OVX) or sham surgery (SHAM), and the osteoporotic condition was characterized after 5 months by microtomographic and morphometric analyses. Calvarial defects were created in osteoporotic rats that immediately received the PVDF-TrFE/BT membrane. After 2 weeks, bone marrow-derived MSCs from healthy rats, characterized by the expression of surface markers using flow cytometry, or phosphate-buffered saline (PBS) (Control) were injected into the defects and bone formation was evaluated 4 weeks post-injection by microtomographic, morphometric, and histological analyses. A reduction in the amount of bone tissue in the femurs of OVX compared with SHAM rats confirmed the osteoporotic condition of the experimental model. More bone formation was observed when the defects were injected with MSCs compared to that with PBS. The modification that we are proposing in this study for the classical GBR approach where cells are locally injected after a membrane implantation may be a promising therapeutic strategy to increase bone formation under osteoporotic condition.

A novel application of nano eggshell/titanium dioxide composite on occluding dentine tubules: an in vitro study

Abstract To synthesize Nano eggshell-titanium-dioxide (EB@TiO2) biocomposite and to evaluate its effectiveness in occluding opened dentine tubules. EB@TiO2 was synthesized and characterized using X-ray diffraction (XRD), and Transmission Electron Microscope (TEM). Sixteen simulated bovine dentine discs were prepared and randomly assigned into four groups according to the following treatment (n = 4): Group 1: No treatment; Group 2: eggshell powder; Group 3: EB@TiO2; Group 4: Sensodyne. These were then agitated in a solution of 1g powder and 40mL water for 3hours. Thereafter, each dentine discs from the respective groups were post-treated for 5 min with 2wt% citric acid to test their acid resistant characteristics. Scanning Electron Microscope (SEM) was used to observe the effectiveness of occluded dentine pre-and post-treatment. The cytotoxicity of the synthesized EB@TiO2 was tested using NIH 3T3 assay. ANOVA was used to evaluate the mean values of the occluded area ratio and the data of MTS assay. This was followed by a multi-comparison test with Bonferroni correction (α = .05). The XRD confirmed that EB@TiO2 was successfully modified through ball-milling. The TEM revealed the presence of both spherical and irregular particle shape powders. The SEM result showed that EB@TiO2 could effectively occlude open dentine tubules. Equally, the result demonstrated that EB@TiO2 exhibited the highest acid resistant stability post-treatment. NIH 3T3 assay identified that EB@TiO2 had little effect on the NIH 3T3 cell line even at the highest concentration of 100µg/ml. This study suggests that the application of EB@TiO2 effectively occluded dentine tubules and the occlusion showed a high acid resistant stability.

Otimização do procedimento de colagem de braquetes ortodônticos utilizando um recipiente fotoprotetor: passo a passo / Optimization of the bonding procedure of orthodontic brackets using a photoprotective vessel: step-by-step

A resina composta fotoativável é usualmente utilizada para o procedimento de colagem de braquetes ortodônticos. No entanto, seu uso requer cuidados antes da fotoativação, pois sua polimerização pode ocorrer precocemente por outras fontes de luz, que não a de um fotoativador dentário (e.g., luz ambiente). Foi idealizado um recipiente fotoprotetor que permite o armazenamento temporário do conjunto de pinças com os braquetes preparados com resina em sua base, evitando o processo de polimerização da resina antes do momento desejado. Objetivo: este estudo tem como objetivo apresentar uma descrição detalhada do procedimento de colagem de braquetes ortodônticos estéticos cerâmicos, quando se utiliza um recipiente fotoprotetor para otimizar o atendimento. Relato de caso: paciente do sexo feminino, 24 anos de idade, submeteu-se ao tratamento ortodôntico em clínica particular. Foram utilizados braquetes ortodônticos autoligados, cerâmicos de alumina policristalina. A colagem dos braquetes foi realizada na arcada inferior de maneira tradicional, porém se fez uso de um recipiente fotoprotetor (protótipo) para otimizar o procedimento. O recipiente teve como finalidade principal o armazenamento temporário de braquetes ortodônticos apreendidos em pinças ortodônticas, já com resina composta para colagem em suas bases. Concluiu-se a instalação do aparelho ortodôntico com a colocação de um arco ortodôntico redondo Ni-Ti 0,014". Considerações finais: a utilização do recipiente fotoprotetor mostrou-se clinicamente eficaz e apresentou um bom resultado final da satisfação tanto do profissional quanto do paciente. O seu uso foi capaz de reduzir o tempo de cadeira do paciente durante o procedimento e impediu a polimerização precoce da resina composta de colagem utilizada. (AU)

The photo-activated resin composite is usually used for the bonding procedure of orthodontic brackets. However, their use requires caution prior to photoactivation, as their polymerization may occur early by light sources other than a dental photoactivator (e.g. ambient light). A photoprotective vessel has been developed to allow temporary storage of the clamps assembly with the resin-prepared brackets, avoiding the polymerization process of the resin prior to the desired moment. Objective: this study purpose was to present a detailed description of the bonding procedure of ceramic orthodontic brackets when using a photoprotective vessel to optimize care. Case report: a 24-year-old female patient underwent orthodontic treatment in a private practice. Orthodontic brackets of polycrystalline alumina ceramics were used for treatment. Bracket bonding was performed in the lower arch in the traditional manner, however a photoprotective vessel (prototype) was used to optimize the procedure. The main purpose of the vessel was the temporary storage of orthodontic brackets- -clamps assembly, already with composite resin for bonding in their bases. The installation of the orthodontic appliance was finished with the placement of a 0.014" round Ni-Ti orthodontic arch. Final considerations: the use of the photoprotective vessel was clinically effective and with a good end result in both professional and patient satisfaction. Its use was able to reduce the patient's chair time during the procedure and prevented the early polymerization of the bonded composite resin used. (AU)

Influência da conicidade e do ponto de imobilização na flexibilidade dos instrumentos de níquel-titânio rotatórios RaCe / Influence of taper and immobilization point on the flexibility of RaCe nickel-titanium rotary instruments

Objetivo: esse estudo comparou a flexibilidade de instrumentos de níquel-titânio rotatórios com diferentes conicidades, em diferentes diâmetros da haste helicoidal cônica (D3 e D6). Métodos: trinta instrumentos RaCe (FKG, La Chaux-de Fonds, Suíça), #40 (D0 = 40), com 25 mm de comprimento, foram divididos em três grupos (n = 10), de acordo com sua conicidade. No teste de flexão em cantiléver (45 graus), foram realizadas duas avaliações, com cargas aplicadas, em D3 e D6, para cada grupo. Resultados: a comparação das cargas aplicadas em D3 e D6 nos instrumentos RaCe com diferentes conicidades mostrou valores de carga máxima significativamente diferentes para flexionar os instrumentos: D3 < D6, com a flexibilidade em D3 maior do que em D6. A comparação das cargas aplicadas em D3 nos três grupos revelou diferenças significativas entre os grupos (p < 0,0001), enquanto o teste Student-Newman-Keuls (SNK) mostrou diferenças de flexibilidade entre os três grupos: 0,06 < 0,04 < 0,02mm/mm. O mesmo resultado foi encontrado na comparação da força aplicada em D6. Conclusões: a flexibilidade do instrumento aumenta com a redução da conicidade (p < 0,05) e diminui com o aumento no diâmetro do eixo helicoidal (p < 0,05).

Mechanical properties of anatomic finishing files: xp-endo finisher and xp-clean

Abstract The aim of the present study was to evaluate the cyclic fatigue of two anatomic finishing files: XP-Endo Finisher and XP-Clean. Roughness pattern and the micro-hardness of the files were also assessed. Instruments were subjected to cyclic fatigue resistance measuring the time to fracture in an artificial stainless-steel canal with a 60° angle and a 5-mm radius of curvature. The fracture surface of all fragments was examined with a scanning electron microscope. The roughness of the working parts was quantified by using a profilometer and the micro-hardness test was carried out using a Vickers hardness tester. Results were statistically analyzed using a student´s t-test at a significance level of P < 0.05. Weibull analysis was also performed. XP-Endo Finisher presented significantly longer cyclic fatigue life than XP-Clean instruments (P<0.05). XP-Endo Finisher was able to withstand 1000% more cycles to fracture when compared to XP-Clean instruments. SEM visual inspection of the fracture surfaces revealed fractographic characteristics of ductile fracture in all tested instruments; wide-ranging forms of dimples were identified and no plastic deformation in the helical shaft of the fractured instruments was observed. When mean life was compared XP-Endo Finisher lasted longer than XP-Clean with a probability of 99.9%. XP-Endo Finisher instruments also exhibited significantly lower roughness than XP-Clean instruments (P<0.05). No differences in the micro-hardness was observed between the files (P>0.05). It can be concluded that XP-Endo Finisher instruments showed improved performance when compared with XP-Clean instruments, demonstrating higher cyclic fatigue resistance and lower roughness.

Resumo O objetivo do presente estudo foi avaliar a fadiga cíclica de dois instrumentos finalizadores anatômicos: XP-Endo Finisher e XP-Clean. O padrão de rugosidade e a micro dureza dos instrumentos também foram avaliados. Os instrumentos foram submetidos à resistência à fadiga cíclica, medindo o tempo de fratura em um canal artificial de aço inoxidável com um ângulo de 60 ° e um raio de curvatura de 5 mm. A superfície de fratura de todos os fragmentos foi examinada com um microscópio eletrônico de varredura. A rugosidade dos instrumentos foi quantificada usando um perfilômetro e o teste de micro dureza foi realizado usando um testador de dureza Vickers. Os resultados foram analisados ​​estatisticamente usando o teste t de student em um nível de significância de p<0,05. A análise Weibull também foi realizada. XP-Endo Finisher apresentou vida de fadiga cíclica significativamente mais longa do que os instrumentos XP-Clean (p<0,05). XP-Endo Finisher foi capaz de suportar 1000% mais ciclos para fratura quando comparado aos instrumentos XP-Clean. A inspeção visual em microscópio eletrônico de varredura das superfícies de fratura revelou características fractográficas da fratura dúctil em todos os instrumentos testados. Não foi observada deformação plástica no eixo helicoidal dos instrumentos fraturados. Quando o tempo para a fratura foi comparado entre os instrumentos, o XP-Endo Finisher durou mais do que o XP-Clean com uma probabilidade de 99,9%. Os instrumentos XP-Endo Finisher também exibiram uma rugosidade significativamente menor do que os instrumentos XP-Clean (p<0,05). Não foram observadas diferenças na micro dureza entre os arquivos (p>0,05). Pode-se concluir que os instrumentos XP-Endo Finisher apresentaram desempenho melhorado em comparação com os instrumentos XP-Clean, demonstrando maior resistência à fadiga cíclica e menor rugosidade.

Apically extruded debris in filling removal of curved canals using 3 NiTi systems and hand files

Abstract The aim of this study was to assess the amount of apically extruded debris during filling removal with WaveOne Gold (WOG), ProTaper Universal Retreatment (PTR), D-RaCe Retreatment (DRR) or hand files (HF), to compare the working time during filling removal, and to describe failures of NiTi instruments. Forty mesiobuccal roots of maxillary first molars were prepared with WOG Primary, obturated and divided into 4 groups (n=10), according to the instruments used: WOG, PTR, DRR or HF. Distilled water was used as irrigant and the extruded debris were collected in Eppendorf tubes and dried. The amount of extruded debris was determined by subtracting the final from the initial weight. The time of filling removal for each canal was recorded and the instruments used were analyzed pre and post-operatively by SEM. Kruskal-Wallis and Dunn's test analyzed extruded debris data and ANOVA, followed by Tukey's test, compared the working time data (a=0.05). Instrument deformation and fracture were described. WOG produced significantly less debris compared with HF and DRR (p<0.05), and similar to PTR (p>0.05). HF, PTR and DRR showed no significant difference (p>0.05). Working time in HF group was significantly higher than others (p<0.05). SEM analyses showed, from the 18 instruments evaluated, 3 fractures and 10 deformations. All instruments tested caused debris extrusion. WOG was associated with less extrusion than DRR and HF. Filling removal with HF was slower than with the other instruments. All NiTi systems presented fracture and deformation.

Resumo O objetivo deste estudo foi avaliar a extrusão apical de debris durante a desobturação com WaveOne Gold (WOG), ProTaper Universal Retratamento (PTR), D-RaCe (DRR) ou limas manuais (HF), comparar o tempo de trabalho durante a desobturação, e descrever as falhas dos instrumentos de NiTi. Quarenta canais de raízes mésio-vestibulares de primeiros molars superiores foram preparados com WOG Primary, obturados e divididos em 4 grupos (n = 10), de acordo com os instrumentos a serem utilizados: WOG, PTR, DRR ou HF. Água destilada foi utilizada como irrigante, e os debris extruídos foram coletados em tubos Eppendorf e secos. A quantidade de debris extruídos foi determinada subtraindo-se o peso inicial do peso final. O tempo de cada desobturação foi anotado e os instrumentos utilizados foram analisados no pré e pós-operatório em MEV. Os testes Kruskal-Wallis e Dunn foram utilizados para analisar os dados da extrusão de debris, e os testes ANOVA e Tukey para comparar os dados do tempo de trabalho (a=0.05). As deformações e fraturas dos instrumentos foram descritas. O grupo WOG produziu significativamente menos debris quando comparado aos grupos HF e DRR (p<0.05), e foi similar ao grupo PTR (p>0.05). Os grupos HF, PTR e DRR não apresentaram diferença estatisticamente significante (p>0.05). O tempo de trabalho no grupo HF foi significativamente maior do que nos outros grupos (p<0.05). A análise em MEV mostrou que, dos 18 instrumentos avaliados, 3 fraturaram e em 10 foi observado deformação. Todos os sistemas testados causaram extrusão apical de debris. WOG foi associado com menor extrusão do que DRR e HF. A desobturação com HF foi mais lenta do que com os demais instrumentos. Todos os sistemas de NITI apresentaram fratura e deformação.

Influence of biomaterials on scintigraphic diagnosis of periprosthetic infections. Ceftizoxime-99m technetium model

Abstract Purpose: To compare the influence of two metallic implants in the diagnosis of periprosthetic infection using 99m technetium-labeled ceftizoxime. Methods: Twenty rats were randomly divided into four groups, which received sterile and contaminated titanium and stainless steel implants. After 3 weeks, scintilographic images were obtained using a gamma chamber. Radioactivity counts were obtained for the region of interest (ROI) on the operated and non-operated paws. Results: Groups A, B, and C showed homogenous distribution of the radiopharmaceutical. Hyper uptake was observed in the operated paw from group D. The ROI target count was higher in the two groups with stainless steel implants. Among the control groups, the count was higher in the stainless steel group. Furthermore, among the contaminated groups, the uptake was higher in the stainless steel group, with a significant difference. The target: non-target ratio was significantly lower in the control and contaminated groups with both titanium and stainless steel, but the comparison between control groups and contaminated groups was only significant in the former. The cpm/g observed after a decay of 48h showed statistically significant differences between groups. Conclusion: Different biomaterials used in implants have an influence on the results of scintigraphy with 99mTc-CFT.

Cyclic flexural fatigue resistance of NiTi Controlled Memory and Blue Technology instruments after torsional preloading

Abstract Objective The aim of this study was to evaluate the influence of torsional preloading on the cyclic flexural fatigue resistance of thermally treated NiTi instruments. Material and Methods Ten new instruments New Hyflex CM (HF 30.06; Coltene/Whaladent Inc.), Typhoon CM (TYP 30.06; Clinician's Choice Dental Products) and Vortex Blue (VB 30.06; Dentsply Tulsa Dental) were chosen, based on geometry and specific characteristics of the manufacturing process. The new instruments of each system were tested in a bench device to determine their fatigue resistance through mean value of number of cycles to failure (Nf) (Control Group - CG). Another group of 10 new HF, TYP and VB instruments were submitted to 20 cycles of torsional straining between 0° and 180° (Experimental Group - EG) and then submitted to fatigue until rupture under the same conditions of the CG. Tested instruments were examined by scanning electron microscopy (SEM). Data were analyzed using one-way analysis of variance and post hoc Tukey's test (α=.05). Results Higher fatigue resistance was accomplished by HF instruments, followed by VB and TYP (p<0.05). During the torsional preloading, the lowest mean torque value was observed for TYP instruments (p<0.05). The torsional preload caused a significant reduction in the Nf values (p<0.05) of about 20%, 39% and 45% for instruments HF, VB and TYP, respectively. Longitudinal cracks, generated during the torsional preloading, were present in VB files, but were not observed in the CM instruments (HF and TYP). Conclusions In conclusion, the flexural fatigue resistance of thermally treated instruments is diminished after cyclic torsional loading.

Comparison of deflection forces of esthetic archwires combined with ceramic brackets

Abstract Coated archwires and ceramic brackets have been developed to improve facial esthetics during orthodontic treatment. However, their mechanical behavior has been shown to be different from metallic archwires and brackets. Therefore, the aim of this study was to compare the deflection forces in coated nickel-titanium (NiTi) and esthetic archwires combined with ceramic brackets. Material and Methods Non-coated NiTi (NC), rhodium coated NiTi (RC), teflon coated NiTi (TC), epoxy coated NiTi (EC), fiber-reinforced polymer (FRP), and the three different conventional brackets metal-insert polycrystalline ceramic (MI-PC), polycrystalline ceramic (PC) and monocrystalline ceramic (MC) were used. The specimens were set up on a clinical simulation device and evaluated in a Universal Testing Machine (Instron). An acrylic device, representative of the right maxillary central incisor was buccolingually activated and the unloading forces generated were recorded at 3, 2, 1 and 0.5 mm. The speed of the testing machine was 2 mm/min. ANOVA and Tukey tests were used to compare the different archwires and brackets. Results The brackets presented the following decreasing force ranking: monocrystalline, polycrystalline and polycrystalline metal-insert. The decreasing force ranking of the archwires was: rhodium coated NiTi (RC), non-coated NiTi (NC), teflon coated NiTi (TC), epoxy coated NiTi (EC) and fiber-reinforced polymer (FRP). At 3 mm of unloading the FRP archwire had a plastic deformation and produced an extremely low force in 2; 1 and 0.5 mm of unloading. Conclusion Combinations of the evaluated archwires and brackets will produce a force ranking proportional to the combination of their individual force rankings.

Reliability of light microscopy and a computer-assisted replica measurement technique for evaluating the fit of dental copings

Abstract The aim of this in vitro study was to assess the reliability of two measurement systems for evaluating the marginal and internal fit of dental copings. Material and Methods: Sixteen CAD/CAM titanium copings were produced for a prepared maxillary canine. To modify the CAD surface model using different parameters (data density; enlargement in different directions), varying fit was created. Five light-body silicone replicas representing the gap between the canine and the coping were made for each coping and for each measurement method: (1) light microscopy measurements (LMMs); and (2) computer-assisted measurements (CASMs) using an optical digitizing system. Two investigators independently measured the marginal and internal fit using both methods. The inter-rater reliability [intraclass correlation coefficient (ICC)] and agreement [Bland-Altman (bias) analyses]: mean of the differences (bias) between two measurements [the closer to zero the mean (bias) is, the higher the agreement between the two measurements] were calculated for several measurement points (marginal-distal, marginal-buccal, axial-buccal, incisal). For the LMM technique, one investigator repeated the measurements to determine repeatability (intra-rater reliability and agreement). Results: For inter-rater reliability, the ICC was 0.848-0.998 for LMMs and 0.945-0.999 for CASMs, depending on the measurement point. Bland-Altman bias was −15.7 to 3.5 μm for LMMs and −3.0 to 1.9 μm for CASMs. For LMMs, the marginal-distal and marginal-buccal measurement points showed the lowest ICC (0.848/0.978) and the highest bias (-15.7 μm/-7.6 μm). With the intra-rater reliability and agreement (repeatability) for LMMs, the ICC was 0.970-0.998 and bias was −1.3 to 2.3 μm. Conclusion: LMMs showed lower interrater reliability and agreement at the marginal measurement points than CASMs, which indicates a more subjective influence with LMMs at these measurement points. The values, however, were still clinically acceptable. LMMs showed very high intra-rater reliability and agreement for all measurement points, indicating high repeatability.