BMP-Binding Polysulfonate Brushes to Control Growth Factor Presentation and Regulate Matrix Remodelling.

Bone morphogenetic proteins (BMPs) are important targets to incorporate in biomaterial scaffolds to orchestrate tissue repair. Glycosaminoglycans (GAGs) such as heparin allow the capture of BMPs and their retention at the surface of biomaterials at safe concentrations. Although heparin has strong affinities for BMP2 and BMP4, two important types of growth factors regulating bone and tissue repair, it remains difficult to embed stably at the surface of a broad range of biomaterials and degrades rapidly in vitro and in vivo. In this report, biomimetic poly(sulfopropyl methacrylate) (PSPMA) brushes are proposed as sulfated GAG mimetic interfaces for the stable capture of BMPs. The growth of PSPMA brushes via a surface-initiated activator regenerated by electron transfer polymerization is investigated via ellipsometry, prior to characterization of swelling and surface chemistry via X-ray photoelectron spectroscopy and Fourier transform infrared. The capacity of PSPMA brushes to bind BMP2 and BMP4 is then characterized via surface plasmon resonance. BMP2 is found to anchor particularly stably and at high density at the surface of PSPMA brushes, and a strong impact of the brush architecture on binding capacity is observed. These results are further confirmed using a quartz crystal microbalance with dissipation monitoring, providing some insights into the mode of adsorption of BMPs at the surface of PSPMA brushes. Primary adsorption of BMP2, with relatively little infiltration, is observed on thick dense brushes, implying that this growth factor should be accessible for further binding of corresponding cell membrane receptors. Finally, to demonstrate the impact of PSPMA brushes for BMP2 capture, dermal fibroblasts were then cultured at the surface of functionalized PSPMA brushes. The presence of BMP2 and the architecture of the brush are found to have a significant impact on matrix deposition at the corresponding interfaces. Therefore, PSPMA brushes emerge as attractive coatings for scaffold engineering and stable capture of BMP2 for regenerative medicine applications.

Determination of Prevalence of Dental Erosion in 12 - 14 Years School Children and Its Relationship with Dietary Habits.

OBJECTIVE: To determine the frequency of dental erosion in 12-14 years school children and its association with dietary habits. STUDY DESIGN: Observational cross-sectional analytical study. PLACE AND DURATION OF STUDY: Fatima Jinnah Dental College, Karachi, from January to June 2010. METHODOLOGY: School children aged between 12 - 14 years were included in this study. Dental erosion was detected by visual examination. Aself-developed questionnaire was used to assess the dietary habits of children. Acidic diet was considered a diet that has an acidic pH. The amount of consumption of acidic drinks and food per week was categorized into low consumption (1 - 7 times / week) and medium consumption (8 - 21 times / week). Chi-square test was applied to see any statistical difference between diet and tooth erosion at 95% CI. RESULTS: The results showed a high frequency of (46%) dental erosion in children, which was significantly higher (p < 0.001) in children with more acidic diet. CONCLUSION: This study highlights the impact of dietary habits on the prevalence of dental erosion in children. Acidic diets need to be controlled in frequency to prevent dental erosion.

Overhanging amalgam restorations by undergraduate students.

OBJECTIVE: To determine the frequency of overhanging margins in amalgam restorations done by undergraduate students at Fatima Jinnah Dental College Hospital, Karachi. STUDY DESIGN: Observational study. PLACE AND DURATION OF STUDY: Department of Operative Dentistry, Fatima Jinnah Dental Hospital, Karachi, from January to June 2009. METHODOLOGY: Patients aged 20 - 45 years attending the Department of Operative Dentistry requiring class-II restorations were included in the study. Whereas, third molars, overlapped proximal surfaces, teeth adjacent to edentulous spaces and pregnant females were excluded. One hundred and fifty patients were selected randomly aged between 20 - 45 years requiring class-II restorations. Posterior Bitewing radiographs were taken and 1600 surfaces were examined. Restorations were done by undergraduate students at Fatima Jinnah Dental College Hospital, Karachi. Chi-square test was utilized to analyze the relationship between location and surface of overhang. RESULTS: Overhanging amalgam restorations were common in the restorations done by undergraduate students (58%). The occurrence of overhangs was more frequent on the distal surfaces (56%) Although the association of amalgam overhangs with the surfaces of the teeth was significant (p < 0.0001), overhangs were not significantly associated with the location of the teeth (p < 0.063). CONCLUSION: Overhanging restorations were present in approximately 58% of all proximal amalgam restorations done by undergraduate students.