RESUMEN
OBJECTIVES: A better understanding of the biological processes controlling osseointegration at the bone-to-implant interface is needed. The aim of this study was to examine which are the molecular and biochemical variables that are significantly related to osseointegration, using multiple regression analysis. MATERIALS AND METHODS: Titanium coins were placed into the tibial cortical bone of New Zealand White rabbits and evaluated using pull-out test after 4 and 8 weeks of healing. Correlations between pull-out and several markers from tissue fluid (Lactate dehydrogenase [LDH] and Alkaline phosphatase [ALP] activities and total protein content) and peri-implant bone tissue (total protein, RNA and DNA content, implant area covered with bone and gene expression of osteoblast, osteoclast and inflammation markers) were used to assess the importance of these parameters in bone healing and in relation to implant performance. RESULTS: Our results showed a negative correlation between the content of DNA, RNA and total protein at the peri-implant bone tissue and the pull-out force, indicating that as bone matures and implant becomes more osseointegrated, the organic content of bone decreases. The negative correlation found between pull-out force and ALP activity pointed to a delayed healing in implants with lower pull-out values and primary mineralization still ongoing. LDH activity and total protein content in the tissue fluid were as well negatively correlated with the pull-out force. Finally, a positive correlation was observed between the pull-out force and the expression of the osteoblast and the bone resorption markers, being osteocalcin and collagen-I the best predictive markers for osseointegration after 4 and 8 weeks of healing respectively. CONCLUSIONS: These results suggest that the evaluation of these markers could be relevant for the assessment of new implant surfaces for rapid bone healing and improved implant performance.
Asunto(s)
Biomarcadores/metabolismo , Implantes Dentales , Oseointegración/fisiología , Tibia/metabolismo , Titanio/metabolismo , Fosfatasa Alcalina/metabolismo , Animales , Densidad Ósea , ADN/metabolismo , Femenino , Implantes Experimentales , L-Lactato Deshidrogenasa/metabolismo , Ensayo de Materiales , Proteínas/metabolismo , ARN/metabolismo , Conejos , Propiedades de Superficie , Tibia/cirugía , Titanio/química , Cicatrización de HeridasRESUMEN
The aim of this study was to establish a wear model for testing composite filling materials with abrasion properties closer to a clinical situation. In addition, the model was used to evaluate the effect of filler volume and particle size on surface roughness and wear resistance. Each incisor tooth was prepared with nine identical standardized cavities with respect to depth, diameter, and angle. Generic composite of 3 different filler volumes and 3 different particle sizes held together with the same resin were randomly filled in respective cavities. A multidirectional wet-grinder with molar cusps as antagonist wore the surface of the incisors containing the composite fillings in a bath of human saliva at a constant temperature of 37°C. The present study suggests that the most wear resistant filling materials should consist of medium filling content (75%) and that particles size is not as critical as earlier reported.
Asunto(s)
Resinas Compuestas/química , Materiales Dentales/química , Alisadura de la Restauración Dental , Acetofenonas/química , Grabado Ácido Dental , Bisfenol A Glicidil Metacrilato/química , Preparación de la Cavidad Dental/clasificación , Pulido Dental , Restauración Dental Permanente , Humanos , Incisivo , Microscopía Electrónica de Rastreo , Tamaño de la Partícula , Ácidos Fosfóricos/química , Polietilenglicoles/química , Polimerizacion , Ácidos Polimetacrílicos/química , Saliva/fisiología , Silanos/química , Dióxido de Silicio/química , Espectroscopía Infrarroja por Transformada de Fourier , Propiedades de Superficie , Temperatura , Abrasión de los Dientes/fisiopatología , Microtomografía por Rayos X , Circonio/químicaRESUMEN
Previous studies have shown that bone-to-implant attachment of titanium implants to cortical bone is improved when the surface is modified with hydrofluoric acid. The aim of this study was to investigate if biological factors are involved in the improved retention of these implants. Fluoride was implemented in implant surfaces by cathodic reduction with increasing concentrations of HF in the electrolyte. The modified implants were placed in the cortical bone in the tibias of New Zealand white rabbits. After 4 weeks of healing, wound fluid collected from the implant site showed lower lactate dehydrogenase activity and less bleeding in fluoride-modified implants compared to control. A significant increase in gene expression levels of osteocalcin and tartrate-resistant acid phosphatase (TRAP) was found in the cortical bone attached to Ti implants modified with 0.001 and 0.01 vol.% HF, while Ti implants modified with 0.1% HF showed only induced TRAP mRNA levels. These results were supported by the performed micro-CT analyses. The volumetric bone mineral density of the cortical bone hosting Ti implants modified with 0.001% and 0.01% HF was higher both in the newly woven bone (<100 microm from the interface) and in the older Haversian bone (>100 microm). In conclusion, the modulation of these biological factors by surface modification of titanium implants with low concentrations of HF using cathodic reduction may explain their improved osseointegration properties.
Asunto(s)
Calcificación Fisiológica/fisiología , Galvanoplastia/métodos , Fluoruros/química , Osteogénesis/fisiología , Prótesis e Implantes , Tibia/cirugía , Titanio/química , Animales , Cristalización/métodos , Ensayo de Materiales , Diseño de Prótesis , Conejos , Propiedades de Superficie , Tibia/patologíaRESUMEN
Etching is used for the surface modification of titanium to improve the implant performance in bone. In this study, pure titanium implants were surface modified by a cathodic reduction process by using hydrofluoric acid (HF) at various concentrations (0.001, 0.01, and 0.1 vol %) and a constant current of 1 mA/cm(2). The resulting surface microtopographies were analyzed by atomic force microscopy, scanning electron microscopy, and profilometry, while the surface chemical contents were evaluated by time of flight secondary ion mass spectrometry. The competitive forces between ionic surface implementation induced by the current direction and the HF etching effect on titanium were highlighted. The implant performance was evaluated in an in vivo rabbit model by using a pull-out test method. The group of implants modified with 0.01% HF showed the highest retention in bone. Fluoride and hydride amounts measured in the surfaces, as well as surface skewness (S(sk)), kurtosis (S(ku)), and core fluid retention (S(ci)) were positively correlated to the implant's retention in bone in vivo. Frequently used parameters for characterizing the implant, such as oxide content and the average height deviation from the mean plane (S(a)), were not correlated to implant performance, suggesting that these parameters are not the most important in predicting the implant performance.
Asunto(s)
Ácido Fluorhídrico/química , Implantación de Prótesis , Titanio/química , Animales , Femenino , Microscopía de Fuerza Atómica , Microscopía Electrónica de Rastreo , Oxidación-Reducción , Conejos , Propiedades de SuperficieRESUMEN
Fluoride-modification of dental titanium (Ti) implants is used to improve peri-implant bone growth and bone-to-implant contact and adhesion strength. In this study, the surface topography, chemistry and biocompatibility of polished Ti surfaces treated with hydrofluoric acid solution (HF) were studied. Murine osteoblasts (MC3T3-E1) were cultured on the different groups of Ti surfaces. Surfaces treated with HF had higher roughness, lower cytotoxicity level and better biocompatibility than controls. For short treatment times (40 and 90 s), fluorine was detected only within the first 5 nm of the surface layer (X-ray Photoemission Spectroscopy, XPS), whereas longer treatment time (120 and 150 s) caused fluoride ions to penetrate deeper (Secondary Ion Mass Spectrometry, SIMS). These results suggest that submerging Ti implants in a weak HF solution instigate time-dependant specific surface changes that are linked to the improved biocompatibility of these surfaces.
Asunto(s)
Ácido Fluorhídrico/farmacología , Propiedades de Superficie/efectos de los fármacos , Titanio/química , Animales , Adhesión Celular/efectos de los fármacos , Línea Celular , Supervivencia Celular/efectos de los fármacos , Implantes Dentales , Ratones , Microscopía de Fuerza Atómica , Microscopía Electrónica de Rastreo , Reacción en Cadena de la Polimerasa de Transcriptasa InversaRESUMEN
The aim of the present study was to investigate the biological mechanisms of the functional attachment of fluoride-modified titanium implants to cortical bone by studying the association of the pull-out test results with gene expression of osteoblast (runx2, osteocalcin, collagen-I and IGF-I), osteoclast (TRAP, H(+)-ATPase and calcitonin receptor) and inflammation (TNF-alpha, IL-6 and IL-10) markers from peri-implant bone tissue using real-time RT-PCR, following a 4- and 8-week healing period. After implant detachment, wound fluid from the implant site was collected for LDH and ALP activity analysis. A new method to study volumetric bone mineral density (vBMD) of sub-implant cortical bone was developed using micro-computed tomography. Our results show lower LDH activity and TRAP mRNA levels in fluoride implants after 4 weeks of healing, yet no differences were found either on the pull-out force or expression of bone formation marker genes. After 8 weeks of healing, both pull-out, vBMD and osteocalcin, runx2 and collage type I gene expression were higher in fluoride implants. In conclusion, fluoride-modified implants seem to modulate both inflammation and bone resorption/formation events at the bone-implant interface, suggesting that these biological effects are an intrinsic part of the clinical performance of this surface.