Fluid shear stress (FSS) caused by interstitial fluid flow within trabecular bone cavities under mechanical loading is the key factor of stimulating biological response of bone cells. Therefore, to investigate the FSS distribution within cancellous bone is important for understanding the transduction process of mechanical forces within alveolar bone and the regulatory mechanism at cell level during tooth development and orthodontics. In the present study, the orthodontic tooth movement experiment on rats was first performed. Finite element model of tooth-periodontal ligament-alveolar bone based on micro computed tomography (micro-CT) images was established and the strain field in alveolar bone was analyzed. An ideal model was constructed mimicking the porous structure of actual rat alveolar bone. Fluid flow in bone was predicted by using fluid-solid coupling numerical simulation. Dynamic occlusal loading with orthodontic tension loading or compression loading was applied on the ideal model. The results showed that FSS on the surface of the trabeculae along occlusal direction was higher than that along perpendicular to occlusal direction, and orthodontic force has little effect on FSS within alveolar bone. This study suggests that the orientation of occlusal loading can be changed clinically by adjusting the shape of occlusal surface, then FSS with different level could be produced on trabecular surface, which further activates the biological response of bone cells and finally regulates the remodeling of alveolar bone.
Objective To assess the clinical efficacy and treatment-induced side effects of intravesically administered bacillus calmette-guerin (BCG) plus chemotherapy following TURB-t in patients with superficial bladder cancer compared with BCG alone.Methods Randomized controlled trials (RCTs) were identified from PubMed (1950 to December 2006), Ovid (1966 to December 2006), EMbase (1984 to December 2006), The Cochrane Library (Issue 4, 2006), CBM (1978 to 2006) and VIP (1989 to 2006). We also handsearched relevant published and unpublished reports as well as their references.The quality of included trials was evaluated by two reviewers. We used The Cochrane Collaboration’ s RevMan 4.2.9 software for statistical analysis. Results Four studies involving 681 patients were included. Meta-analyses showed that, in patients with Ta and T1 bladder cancer, there was a significant difference in the recurrence rate between intravesically administered BCG plus chemotherapy and BCG alone (RR 0.69, 95%CI 0.53 to 0.90). In patients with Tis bladder cancer, no significant difference was found in the recurrence rate between the two groups (RR 1.22, 95%CI 0.97 to 1.54). In patients with Ta, T1 and Tis bladder cancer, no statistically significant difference was found in the incidence of side effects (RR 0.85, 95%CI 0.70 to 1.03). Conclusion Compared with BCG alone, intravesically administered BCG plus chemotherapy in patients with Ta and T1 superficial bladder cancer can reduce the incidence of tumor recurrence more effectively. For patients with Tis bladder cancer, the two therapeutic regimens do not differ in the incidence of tumor recurrence. The two regimens have similar side effects. There is a moderate possibil ity of selection bias, performance bias and publ ication bias in the small number of included studies, which weakens the strength of the evidence of our results. Better evidence from more high-quality double-blind randomized controlled trials is needed.
