Miguel Alcaraz-Baños

Melatonin plus porcine bone on discrete calcium deposit implant surface stimulates osteointegration in dental implants

Abstract:  The aim of this study was to evaluate the effect of the topical application of melatonin mixed with collagenized porcine bone to accelerate the osteointegration on the rough discrete calcium deposit (DCD) surface implants in Beagle dogs 3 months after their insertion. In preparation for subsequent insertion of dental implants, lower premolars and molars were extracted from 12 Beagle dogs. Each mandible received three parallel wall implants with discrete calcium deposit (DCD) surface of 4 mm in diameter and 10 mm in length. The implants were randomly assigned to the distal sites on each side of the mandible in three groups: group I implants alone, group II implants with melatonin and group III implants with melatonin and porcine bone. Prior to implanting, 5 mg lyophylized powdered melatonin was applied to one bone hole at each side of the mandible. None was applied at the control sites. Ten histological sections per implant were obtained for histomorphometric studies. After a 4‐wk treatment period, melatonin significantly increased the perimeter of bone that was in direct contact with the treated implants (P < 0.0001), bone density (P < 0.0001), new bone formation (P < 0.0001) in comparison with control implants. Topical application of melatonin on DCD surface may act as a biomimetic agent in the placement of endo‐osseous dental implants and enhance the osteointegration. Melatonin combined with porcine bone on DCD implants reveals more bone to implant contact at 12 wk (84.5 ± 1.5%) compared with melatonin treated (75.1 ± 1.4%) and nonmelatonin treated surface implants (64 ± 1.4%).

In‐vivo behavior of Si‐hydroxyapatite/polycaprolactone/DMB scaffolds fabricated by 3D printing

Scaffolds made of polycaprolactone and nanocrystalline silicon-substituted hydroxyapatite have been fabricated by 3D printing rapid prototyping technique. To asses that the scaffolds fulfill the requirements to be considered for bone grafting applications, they were implanted in New Zealand rabbits. Histological and radiological studies have demonstrated that the scaffolds implanted in bone exhibited an excellent osteointegration without the interposition of fibrous tissue between bone and implants and without immune response after 4 months of implantation. In addition, we have evaluated the possibility of improving the scaffolds efficiency by incorporating demineralized bone matrix during the preparation by 3D printing. When demineralized bone matrix (DBM) is incorporated, the efficacy of the scaffolds is enhanced, as new bone formation occurs not only in the peripheral portions of the scaffolds but also within its pores after 4 months of implantation. This enhanced performance can be explained in terms of the osteoinductive properties of the DBM in the scaffolds, which have been assessed through the new bone tissue formation when the scaffolds are ectopically implanted.

The importance of collimator angle error in volumetric-modulated arc therapy

Purpose To evaluate the dosimetric errors associated with the effect of the collimator angle error in volumetric-modulated arc therapy (VMAT) treatments. Methods and materials Four patients with different planning target volume (PTV) and localisations treated using VMAT were analysed (high-risk prostate, low-risk prostate, head and neck (H&N) and holocranial with hippocampus protection) in terms of dosimetric variations when errors in the collimator angle were introduced. Original plans underwent modifications of the planned collimator angles of ±0·5°, ±1° and ±1·5°. These modified plans were re-calculated using the same original plan fluencies, and the resulting dose–volume histograms and homogeneity index (HI-ICRU) were compared. Results For the high-risk prostate case, there was a noticeable loss of PTV dose coverage for collimator angle errors larger than ±1°, with HI-ICRU relative variations up to 75% in the range analysed. The low-risk prostate case did not present significant changes in organs at risk or PTV dose coverage. For the H&N case, the spinal cord presented changes around 4% for D 0·1 cc . In the holocranial case, optic lens showed dose variations up to 5% for collimator angle errors larger than ±1°. Conclusions The effect of the collimator error in VMAT increased as the PTV increased. For selecting the position of the isocentre, one should be cautious, and whenever possible choose a position close to the geometrical centre of the PTVs in order to avoid or minimise errors from the calibration of the collimator angle.

Bone tissue engineering. Design and development of biologically active vitroceramic-based hybrid materials to be used as bone substitutes

Abstract Purpose To describe the development and characterisation of a vitroceramic material as well as the initial response of adult mesenchymal stem cells (MSCs-A) isolated from bone marrow. Material and methodology The material was obtained by heating glass with composition in mol% 55SiO2-41CaO-4P2O5 by a sol gel method. Cells were isolated from direct iliac crest aspirates from young adult patients. An analysis was performed of the degree of adhesion, proliferation and osteoblastic differentiation of MSCs-A seeded onto the material. Cell differentiation was evaluated through the production of osteocalcin and the loss of the CD90 mesenchymal marker. Cell proliferation on the substrate was performed using the tetrazolium salt reduction method. The seeded material was implanted in a critical defect caused in a rabbit femur in order to determine its osteogenerating capacity; CT observations were carried out. Results MSCs-A se bound to the material, expanded, proliferated and produced mineralised extracellular matrix on the material during the culture period. At the same time, they showed an osteoblastic phenotype, increasing osteocalcin production and losing CD90 expression. The material was partially resorbed at the end of the study. Conclusion The material is cytocompatible, osteoconductive, bioactive and has a capacity to promote osteoblastic differentiation of MSCs-A as well as new bone formation following its implantation in association with MSCs-A; an appropriate matrix for bone tissue regeneration.

Respuesta ósea al implante de espuma de hidroxiapatita (HA-02). Estudio experimental en conejos

Introduccion y objetivos Se ha realizado un estudio experimental en modelo animal para analizar el comportamiento de una espuma de hidroxiapatita (HA-02) como potencial sustituto oseo. Material y metodo En 12 conejos colocamos un implante (espuma HA-02) en las tibias. Los animales fueron sacrificados a la semana, uno, cinco y ocho meses. Se realizo el estudio radiologico y morfologico (microscopia optica y microscopia electronica de barrido). Resultados Se observo crecimiento oseo en todos los periodos del estudio de forma centripeta, alrededor y en el interior del implante, sin presentar tejido fibroso en la intercara implante-hueso huesped y sin reaccion inflamatoria relevante. Tambien se observo una disminucion del volumen de los implantes. Discusion y conclusiones La espuma HA-02 se ha comportado en nuestro estudio como material biocompatible, pues solo provoca respuesta inflamatoria leve durante las dos primeras semanas, osteoconductor al permitir formacion de tejido oseo en su interior y biorreabsorbible al sufrir reabsorcion parcial por mecanismos celulares fagociticos, sin originar productos intermedios. Por ello, puede considerarse la espuma de hidroxiapatita como potencial sustituto del tejido oseo.

Cuidados enfermeros a pacientes intervenidos mediante cirugía radiológica. Caso clínico

We report the case of a 73-year-old man with medical diagnoses of long-standing diabetes mellitus, chronic ischemia of the lower limbs and intermittent claudication, for which the patient had been treated with minimally invasive radiological surgery. On arrival at the radiology unit, the patient had nursing diagnoses of anxiety and fear. Intraoperatively, the client had nursing diagnoses of pain, urine retention and infection risk. At discharge, a collaboration problem was detected and hemorrhagic risk. The patient received individualized nursing care. Interventions were planned following the nursing intervention classification (NIC) and the expected results for these interventions followed the Nursing Outcomes Classification (NOC) taxonomy. The application of an appropriate nursing care plan contributes to making the patients hospital stay easier, more comfortable and less traumatic.Resumen Se presenta el caso clinico de un paciente varon de 73 anos, con los diagnosticos medicos de diabetes mellitus de larga evolucion, isquemia cronica de miembros inferiores y claudicacion intermitente, al que se le ha tratado con cirugia minimamente invasiva radiologica. A su llegada a la unidad de radiologia, el paciente presenta los diagnosticos enfermeros de ansiedad y temor; durante el intraoperatorio dolor, retencion urinaria y riesgo de infeccion, y al alta de la unidad se detecta el problema de colaboracion y el riesgo de hermorragia. Se le prestan cuidados enfermeros individualizados, y se planifican las intervenciones segun las clasificaciones NIC (Nursing Intervention Classification) y los resultados esperados de estas intervenciones segun la taxonomia NOC (Nursing Outcomes Classification). La aplicacion de un correcto plan de cuidados enfermeros ayuda a que la estancia del paciente en el quirofano sea mas facil, confortable y menos traumatica.