ABSTRACT
The influence of sodium fluoride (NaF) concentration in mouthwashes on the properties of superelastic NiTi orthodontic wires has been studied. In this work, 55.8%Ni and 44.2%Ti (in weight) wires were introduced in commercial mouthwashes with different NaF contents (0, 130, 200 and 380 ppm). The release of Ni2+ and Ti4+ ions was by Inductively Coupled Plasma-Mass Spectrometry (ICP-MS) at 1, 4, 7 and 14 days. Superelastic orthodontic wires present at oral temperature the austenitic phase which is transformed into a plastic phase (martensite) by cooling. The temperatures at which this occurs are influenced by the chemical composition. The release of ions from the wire will produce variations in the temperatures and stresses of the stress-induced martensitic transformation. Ms, Mf, As, Af were determined by Differential Scanning Calorimeter (DSC). The transformation stresses (austenite to stress induce martensite) were determined with a servo-hydraulic testing machine at 37 °C. The surfaces for the different times and mouthwash were observed by Scanning Electron Microscope (SEM). The release of Ni2+ in mouthwashes with 380 ppm NaF concentrations reaches 230,000 ppb in 14 days and for Ti4+ 175,000 ppb. When NaF concentrations are lower than 200 ppm the release of Ni and Ti ions is around 1500 ppb after 14 days. This variation in compositions leads to variations in Ms from 27 °C to 43.5 °C in the case of higher NaF concentration. The increasing immersion time and NaF concentrations produce a decrease of Ni in the wires, increasing Ms which exceed 37 °C with the loss of superelasticity. In the same way, the stresses (tooth position corrective) decrease from 270 MPa to 0 MPa due to the martensitic phase. The degradation can produce the growth of precipitates rich in Ti (Ti2Ni). These results are of great interest in the orthodontic clinic in order to avoid the loss of the therapeutic properties of superelastic NiTi due to long immersion in fluoride mouthwashes.
ABSTRACT
BACKGROUND: New tetragonal zirconia polycrystal dental implants stabilized with yttria (Y-TZP) have appeared in the implantology market in the form of single piece or two-piece zircona implant system. These new type of implants improve the aesthetical properties compared to conventional commercially pure (c.p.) titanium used for implants, although the long term mechanical behavior of these new implants is not yet well known. In orthopaedics, the application of zirconia as femoral balls presented an important controversial use due to the premature fracture once implanted. Y-TZP dental implants can be affected by hydrothermal degradation and its behavior should be analysed to avoid a premature fracture. The scientific question behind the study is to analyse if the degradation mechanism observed in orthopaedics applications of Y-TZP is similar to that of Y-TZP for dental applications. MATERIALS AND METHODS: For this purpose, 30 original Y-TZP dental implants and 42 Y-TZP femoral balls fractured in vivo have been studied. Dental implants were submitted to an accelerated hydrothermal degradation to compare with the femoral balls fractured in vivo. Phase transformation as well as the mechanical behaviour of the degraded samples was studied by X ray diffraction and nanoindentation tests, respectively. RESULTS: Results have shown that the fracture mechanism of dental implants does not resemble the mechanism observed in orthopaedic samples, presenting a good long-term behaviour. CONCLUSION: The results ensure the good performance of zirconia dental implants, because the degradation of the ceramic is very limited and does not affect the mechanical properties.
Subject(s)
Dental Implants , Materials Testing , Surface Properties , X-Ray Diffraction , ZirconiumABSTRACT
INTRODUCTION: Antibiotic-loaded bone cements of poly(methyl methacrylate) are considered as very useful biomaterials for the management of corporal deep osseous infections. However, the high prevalence of resistant germs and polymicrobial infections makes it necessary to search for new formulations of bone cements containing antibiotics for local antibacterial therapy. In this work, bone cements loaded with drugs with different mechanism of action were evaluated to determine its antibacterial effectiveness on Pseudomonas aeruginosa. METHODOLOGY: Poly(methyl methacrylate) cements loaded with 10 wt.% of Oleozon®, mixtures of Ciprofloxacin/Meropenem and Ciprofloxacin/Meropenem/Oleozon® were prepared. The in vitro drugs release in water was followed by UV-Vis spectroscopy, and their antibacterial activity against Pseudomonas aeruginosa was evaluated for 11 days using the microdilution method. RESULTS: All the extracts demonstrated an inhibitory effect on the growth of the strain during the whole trial period. Extracts from cement with Oleozon® only presented a total antibacterial inhibitory effect during 20 hours for the extracts taken at day 1 while the extracts from the cements loaded with mixtures of Ciprofloxacin/Meropenem and Ciprofloxacin/Meropenem/Oleozon® showed complete inhibition of the growth of the microorganism, even at 11 days. At the end of the trial period, some of the drugs remained inside the matrices, indicating that they can be released for a longer time in treatments. CONCLUSIONS: The results indicated a positive antibacterial effect by the combined used of the two or the three drugs tested against the Gram-negative bacilli Pseudomonas aeruginosa, so these proposal may be a valid alternative to be considered by surgeons.
Subject(s)
Anti-Bacterial Agents/pharmacology , Bone Cements/pharmacology , Polymethyl Methacrylate/pharmacology , Pseudomonas aeruginosa/drug effects , Anti-Bacterial Agents/pharmacokinetics , Drug Combinations , Microbial Sensitivity TestsABSTRACT
En la actualidad, para el odontólogo resulta un gran desafío poder restaurar la apariencia natural y la anatomía de dientes perdidos. En este trabajo se realiza el reporte de un caso clínico donde se restituye el incisivo central superior derecho, a causa de traumatismo dentomaxilofacial, por un implante Leader® combinado con el relleno óseo Biograft-G®. Se trata de una paciente de 19 años atendida en la consulta multidisciplinaria del Centro Nacional de Estomatología, La Habana, Cuba. La paciente portaba prótesis inmediata a causa de la pérdida del diente 11 por fractura de corona y raíz, con defecto óseo vestibular. A la paciente le ocurría fractura frecuente de la prótesis, viéndose afectada desde el punto de vista estético, social, psicoafectivo y funcional. Después de una evaluación multidisciplinaria y el consentimiento de la paciente, se procedió a la cirugía mediante la técnica de colgajo, colocación de implante Leader® y relleno con Biograft-G® para regenerar el defecto óseo, devolver contorno vestibular y lograr una rehabilitación definitiva. Con este tratamiento, la paciente obtuvo los resultados estéticos y funcionales deseados.
Today is a challenge to restore the natural appearance and anatomy of extracted teeth. In this paper we present a clinical case in which the right upper central incisor is restored, due to the presence of a dentomaxillofacial trauma, through a Leader® implant combined with Biograft-G® bone filler. The patient is a 19 year woman treated in the multidisciplinary consultation of the National Center of Stomatology, Havana, Cuba. The patient had an immediate prosthesis due to a fracture of the crown and root, with vestibular bone defect. The patient frequently fractured the prosthesis, which affected her in terms of aesthetics, social, psychological and functional incorporation. After a multidisciplinary evaluation and the patient's consent, the surgery was performed using the flap technique, the placement of the Leader® implant and the filling with Biograft-G® to regenerate the bone defect, to recover the vestibular contour and to achieve a definitive rehabilitation. With this treatment, the patient obtained the desired aesthetic and functional results.
