RESUMEN
Bone condensation is thought to densify interfacial bone and thus improve implant primary stability, but scant data substantiate either claim. We developed a murine oral implant model to test these hypotheses. Osteotomies were created in healed maxillary extraction sites 1) by drilling or 2) by drilling followed by stepwise condensation with tapered osteotomes. Condensation increased interfacial bone density, as measured by a significant change in bone volume/total volume and trabecular spacing, but it simultaneously damaged the bone. On postimplant day 1, the condensed bone interface exhibited microfractures and osteoclast activity. Finite element modeling, mechanical testing, and immunohistochemical analyses at multiple time points throughout the osseointegration period demonstrated that condensation caused very high interfacial strains, marginal bone resorption, and no improvement in implant stability. Collectively, these multiscale analyses demonstrate that condensation does not positively contribute to implant stability.
Asunto(s)
Proceso Alveolar/cirugía , Densidad Ósea/fisiología , Remodelación Ósea/fisiología , Implantación Dental Endoósea/métodos , Implantes Dentales , Animales , Equipo Dental de Alta Velocidad , Análisis de Elementos Finitos , Ratones , Modelos Animales , Oseointegración/fisiología , Osteotomía , Extracción DentalRESUMEN
The mammalian skeleton performs a diverse range of vital functions, requiring mechanisms of regeneration that restore functional skeletal cell populations after injury. We hypothesized that the Wnt pathway specifies distinct functional subsets of skeletal cell types, and that lineage tracing of Wnt-responding cells (WRCs) using the Axin2 gene in mice identifies a population of long-lived skeletal cells on the periosteum of long bone. Ablation of these WRCs disrupts healing after injury, and three-dimensional finite element modeling of the regenerate delineates their essential role in functional bone regeneration. These progenitor cells in the periosteum are activated upon injury and give rise to both cartilage and bone. Indeed, our findings suggest that WRCs may serve as a therapeutic target in the setting of impaired skeletal regeneration.
Asunto(s)
Proteína Axina/metabolismo , Huesos/citología , Huesos/lesiones , Regeneración Hepática , Animales , Proteína Axina/genética , Linaje de la Célula , Proliferación Celular , Análisis de Elementos Finitos , Ratones , Modelos Teóricos , Vía de Señalización WntRESUMEN
In Spain mumps vaccine is given at the age of 15 months together with measles and rubella vaccines since 1982. Increased numbers of cases and outbreaks of mumps appeared in several autonomous communities in 1995. An outbreak of mumps in the province of.
RESUMEN
In Spain mumps vaccine is given at the age of 15 months together with measles and rubella vaccines since 1982. Increased numbers of cases and outbreaks of mumps appeared in several autonomous communities in 1995. An outbreak of mumps in the province of -