Bioactive Inorganic Materials for Dental Applications: A Narrative Review.

Over time, much attention has been given to the use of bioceramics for biomedical applications; however, the recent trend has been gaining traction to apply these materials for dental restorations. The bioceramics (mainly bioactive) are exceptionally biocompatible and possess excellent bioactive and biological properties due to their similar chemical composition to human hard tissues. However, concern has been noticed related to their mechanical properties. All dental materials based on bioactive materials must be biocompatible, long-lasting, mechanically strong enough to bear the masticatory and functional load, wear-resistant, easily manipulated, and implanted. This review article presents the basic structure, properties, and dental applications of different bioactive materials i.e., amorphous calcium phosphate, hydroxyapatite, tri-calcium phosphate, mono-calcium phosphate, calcium silicate, and bioactive glass. The advantageous properties and limitations of these materials are also discussed. In the end, future directions and proposals are given to improve the physical and mechanical properties of bioactive materials-based dental materials.

Neutrophil Enzyme Myeloperoxidase Modulates Neuronal Response in a Model of Subarachnoid Hemorrhage by Venous Injury.

Background and Purpose: Aneurysmal subarachnoid hemorrhage (SAH) is associated with the development of delayed cognitive deficits. Neutrophil infiltration into the central nervous system is linked to the development of these deficits after SAH. It is however unclear how neutrophil activity influences central nervous system function in SAH. The present project aims to elucidate which neutrophil factors mediate central nervous system injury and cognitive deficits after SAH. Methods: Using a murine model of SAH and mice deficient in neutrophil effector functions, we determined which neutrophil effector function is critical to the development of deficits after SAH. In vivo and in vitro techniques were used to investigate possible pathways of neutrophils effect after SAH. Results: Our results show that mice lacking functional MPO (myeloperoxidase), a neutrophil enzyme, lack both the meningeal neutrophil infiltration (wild type, sham 872 cells/meninges versus SAH 3047, P=0.023; myeloperoxidase knockout [MPOKO], sham 1677 versus SAH 1636, P=NS) and erase the cognitive deficits on Barnes maze associated with SAH (MPOKO sham versus SAH, P=NS). The reintroduction of biologically active MPO, and its substrate hydrogen peroxide (H2O2), to the cerebrospinal fluid of MPOKO mice at the time of hemorrhage restores the spatial memory deficit observed after SAH (time to goal box MPOKO sham versus MPOKO+MPO/H2O2, P=0.001). We find evidence of changes in neurons, astrocytes, and microglia with MPO/H2O2 suggesting the effect of MPO may have complex interactions with many cell types. Neurons exposed to MPO/H2O2 show decreased calcium activity at baseline and after stimulation with potassium chloride. Although astrocytes and microglia are affected, changes seen in astrocytes are most consistent with inflammatory changes that likely affect neurons. Conclusions: These results implicate MPO as a mediator of neuronal dysfunction in SAH through its effect on both neurons and glia. These results show that, in SAH, the activity of innate immune cells in the meninges modulates the activity and function of the underlying brain tissue.

A review of bioceramics-based dental restorative materials.

Currently, much has been published related to conventional resin-based composites and adhesives; however, little information is available about bioceramics-based restorative materials. The aim was to structure this topic into its component parts and to highlight the translational research that has been conducted up to the present time. A literature search was done from indexed journals up to September 2017. The main search terms used were based on dental resin-based composites, dental adhesives along with bioactive glass and the calcium phosphate family. The results showed that in 123 articles, amorphous calcium phosphate (39.83%), hydroxyapatite (23.5%), bioactive glass (16.2%), dicalcium phosphate (5.69%), monocalcium phosphate monohydrate (3.25%), and tricalcium phosphate (2.43%) have been used in restorative materials. Moreover, seven studies were found related to a newly developed commercial bioactive composite. The utilization of bioactive materials for tooth restorations can promote remineralization and a durable seal of the tooth-material interface.

Effect of nano-bioceramics on monomer leaching and degree of conversion of resin-based composites.

The aim of this laboratory study was to evaluate the monomer leaching and degree of conversion (DC) from experimental bioactive resin composites (RBCs) and to do comparison with commercial bulkfill and packable resin composites. Experimental dimethacrylatebased resin composites were reinforced with silanated nano-hydroxyapatite (30 and 45 wt%). The ion leaching and DC of these resin composites were compared and contrasted with SDR™ and Filtek P60™ by using the high performance liquid chromatography (HPLC) and Fourier transform infrared spectroscopy (FTIR), respectively. A significant difference was found in elution of monomer between the resin composites. SDR™ showed significantly high monomer elution and structural changes compared to other resin composites. The DC of bioactive RBCs showed the highest conversion rate after polymerization. Resin composite with nano-hydroxyapatite with the presence of a bioactive component might provide biomimetic approach for the material. Moreover, a low concentration of nanohydroxyapatite nano-fillers have shown better properties than micro-fillers based resin composites.

Assessment of characteristics of patients with cholelithiasis from economically deprived rural Karachi, Pakistan.

BACKGROUND: Gallstones have been regarded as one of the most expensive diseases in Gastroenterology, posing a great economic burden on developing nations. The majority of Pakistani people live in rural areas where healthcare facilities are not available or are very primitive. We aim to assess the characteristics among cholelithiasis patients from rural Karachi so that a prevention campaign can be launched in rural underprivileged settings to reduce the economic burden of this preventable disease. METHOD: A total of 410 patients were included in the study after giving verbal consent as well as written consent. Variables such as age, weight, height, body mass index (BMI), blood pressure, waist circumference, number of children, monthly family income, number of siblings, and number of family members, were considered in this questionnaire. All data was analysed by SPSS ver. 16.0. Mean and standard deviation (SD) were calculated for continuous variables. Frequency and percentages were calculated for categorical variables. RESULTS: Nearly 85.4% of the participants were female. The mean ± S.D. for age was 43.8 ± 9.59. Nearly 61% of the patients were illiterate. All of our patients were from low socioeconomic status and their mean salary ± S.D. was 6915 ± 1992 PKR (1 US $ = 90.37PKR). 75% of them were smokers with mean consumption ± S.D. of 7.5 ± 10 cigarettes per day. Fibre in diet was not used by 83.65% of patients. 40.2% were living in combined families. 61% were living in purchased homes. A positive history of diabetes mellitus was given by 45.1%, family history of cholelithiasis by 61% and history of hypertension by 31.7% of subjects. Soft drink consumption was given by 45.1% of patients; while only 8.5% used snacked daily. Tea was consumed by 95.1% of the subjects. Daily physical activity for 30 minutes was reported by only 13.4% of participants. CONCLUSION: In conclusion, rural dwellers from low socioeconomic strata are neglected patients and illiteracy further adds fuel to the fire by decreasing the contact with the health professionals. Assessment of the characteristics are very important because considering the great socio-economic burden, an intervention strategy in the form of mass media campaign as well as small group discussions in such rural areas can be formulated and applied to high risk populations to reduce the burden and complications of gallstone disease.