Clinical and Radiological Outcomes for Guided Implant Placement in Sites Preserved with Bioactive Glass Bone Graft after Tooth Extraction: A Controlled Clinical Trial.

The goal of the study was to evaluate marginal bone loss (MBL) after 1-year implant placement using a guided implant surgical (GIS) protocol in grafted sockets compared to non-grafted sites. We followed a parallel study design with patients divided into two groups: grafted group (Test group, n = 10) and non-grafted group (Control, n = 10). A bioactive glass bone graft was used for grafting. A single edentulous site with a minimum bone height ≥11 mm and bone width ≥6 mm confirmed by cone-beam computerized tomography (CBCT) was chosen for implant placement. Tapered hybrid implants that were sandblasted and acid-etched (HSA) were placed using the GIS protocol and immediately loaded with a provisional prosthesis. MBL and implant survival rates (ISR) were assessed based on standardized radiographs and clinical exams. Patients were followed up for 1-year post-loading. MBL after one year, in the control group, was −0.31 ± 0.11 mm (mesial) and −0.28 ± 0.09 mm (distal); and in the test group was −0.35 ± 0.11 mm (mesial) and −0.33 ± 0.13 mm (distal), with no statistical significance (p > 0.05). ISR was 100% in both groups after one year. ISR was similar between groups and the marginal bone changes were comparable one year after functional loading, without statistical significance, suggesting that bioactive glass permitted adequate bone formation. The GIS protocol avoided raising flaps and provided a better position to place implants, preserving the marginal bone around implants.

Osteoblast adhesion dynamics: a possible role for ROS and LMW-PTP.

Reactive oxygen species (ROS) modulate a variety of intracellular events, but their role in osteoblast adhesion and spreading remains unclear. ROS is a very-known physiological modulators of Protein Tyrosine Phosphatases activities, mainly to low molecular weight protein tyrosine phosphatase (LMW-PTP) activity. As this biological mechanism is not clear in osteoblast adhesion, we decided to investigate ROS levels and phosphorylations of FAK and Src, identifying these proteins as potential substrates to LMW-PTP activity. Our results showed that during osteoblast adhesion/spreading (30 min and 2 h of seeding) the intracellular ROS content (hydrogen peroxide) is finely regulated by an effective anti-oxidant system [catalase and Superoxide Dismutase (SOD) activities were evaluated]. During the first 30 min of adhesion, there was an increase in ROS production and a concomitant increase in focal adhesion kinase (FAK) activity after its phosphorylation at Tyrosine 397 (Y397 ). Moreover, after 2 h there was a decrease in ROS content and FAK phosphorylation. There was no significant change in LMW-PTP expression at 30 min or 2 h. In order to validate our hypothesis that LMW-PTP is able to control FAK activity by modulating its phosphorylation status, we decided to overexpress and silence LMW-PTP in this context. Our results showed that FAK phosphorylation at Y397 was increased and decreased in osteoblasts with silenced or overexpressed LMW-PTP, respectively. Together, these data show that ROS modulate FAK phosphorylation by an indirect way, suggesting that a LMW-PTP/FAK supra-molecular complex is involved in transient responses during osteoblast adhesion and spreading.

Exploring anorganic bovine bone granules as osteoblast carriers for bone bioengineering: a study in rat critical-size calvarial defects

It is known that current trends on bone bioengineering seek ideal scaffolds and explore innovative methods to restore tissue function. In this way, the objective of this study was to evaluate the behavior of anorganic bovine bone as osteoblast carrier in critical-size calvarial defects. MC3T3-E1 osteoblast cells (1x10(5) cells/well) were cultured on granules of anorganic bovine bone in 24-well plates and after 24 h these granules were implanted into rat critical-size calvarial defects (group Biomaterial + Cells). In addition, other groups were established with different fillings of the defect: Blood Clot (negative control); Autogenous Bone (positive control); Biomaterial (only granules) and Cells (only MC3T3-E1 cells). After 30 days, the animals were euthanized and the calvaria were technically processed in order to allow histological and morphometric analysis. It was possible to detect blood vessels, connective tissue and newly formed bone in all groups. Particularly in the Biomaterial + Cells group, it was possible to observe a profile of biological events between the positive control group (autogenous bone) and the group in which only anorganic bovine granules were implanted. Altogether, the results of the present study showed that granules of anorganic bovine bone can be used as carrier to osteoblasts and that adding growth factors at the moment of implantation should maximize these results.

Sabe-se que uma das atuais tendências na bioengenharia óssea é procurar um carreador ideal e explorar métodos inovadores para restaurar a função do tecido. Desta forma, nosso objetivo foi avaliar o comportamento do osso bovino inorgânico como carreador de osteoblastos em defeitos ósseos de tamanho crítico em calvária de ratos. Osteoblastos da linhagem MC3T3-E1 (1x10(5) células/poço) foram cultivadas em grânulos de osso bovino inorgânico sob placas de 24 poços e após 24 h esses grânulos foram implantados em defeitos ósseos de tamanho crítico em calvária de ratos. Além deste grupo experimental (Biomaterial + Células), foram estabelecidos outros grupos com diferentes preenchimentos do defeito crítico: coágulo sanguíneo (controle negativo); osso autógeno (controle positivo); Biomaterial (apenas grânulos) e Células (apenas células MC3T3-E1). Após 30 dias, os animais foram eutanasiados e as calvárias foram processadas histotecnicamente, a fim de permitir a análise histológica e morfometria. Nossos resultados mostraram que em todos os grupos avaliados foi possível detectar vasos sanguíneos, tecido conjuntivo e osso neoformado. Em especial para o grupo tratado com Biomaterial + Células, foi possível observar um perfil de eventos biológicos intermediário ao grupo controle positivo (osso autógeno) e o grupo de biomaterial (apenas grânulos inorgânico bovino). Ao todo, nossos resultados mostraram que os grânulos de osso bovino inorgânico podem ser usados como carreador de osteoblastos e que a adição de fatores de crescimento no momento em que ocorre o implante deve maximizar os resultados.