Page 1 Global Scientific Research Journal of Dentistry Effect of Nano-Bioglass Addition to Calcium Hydroxide Cements in Terms of Ions Release, Apatite Formation and Compressive Strength Effect of Nano-Bioglass Addition to Calcium Hydroxide Cements in Terms of Ions Release, Apatite Formation and Compressive Strength Shaymaa I Habib 1 *, Rania E Bayoumi 2 , Sabry A El-Korashy 3 and Rasha M Abdelraouf 1 1 Assistant Professor of Dental Materials, Biomaterials Department, Faculty of Dentistry, Cairo University, Cairo, Egypt. 2 Lecturer of Dental Materials, Biomaterials Department, Faculty of Dentistry (Girls), Azhar University, Cairo, Egypt. 3 Professor of Inorganic Chemistry, Faculty of Science, Ismailia, Suez Canal University, Egypt. 1 rasha.abdelraouf@dentistry.cu.edu.eg Abstract Objective: To evaluate the effect of the nano-bioglass addition to calcium-hydroxide cements regarding ions release, apatite formation and compressive strength. Materials and Methods: Two calcium-hydroxide Ca(OH) 2 liner materials were used; chemical and light-cured. Nano-bioglass (7wt%) was added to both cements. Specimens were prepared and classifed as follows: Group I: Chemical-cured Ca(OH) 2 , and Group II: Light-cured Ca(OH) 2 . Each group was further subdivided according to the added bioactive glass into two subgroups a) control without nano-bioglass, and b) subgroup containing nano-bioglass. Forty disc-shaped-specimens were stored in distilled water at 37 o C (n = 10/subgroup). Half of the specimens in each subgroup were stored for 1 day, while the others for 7 days. The storage media was collected for pH measurement using pH-meter, and then calcium and phosphorus analysis using the atomic-absorption-spectrophotometry. For the apatite-forming ability, test was performed by soaking disc-specimens in phosphate-buffered-saline at 37 ºC (n = 6/subgroup). The endpoint times were 1 day and 7 days. Scanning-Electron-Microscope (SEM) and Energy- Dispersive X-ray-Analysis (EDXA) were used for microstructure and elemental analysis of the specimens’ surfaces. For the compressive-strength-test, twenty cylindrical specimens were prepared (n = 5/subgroup) and tested using universal-testing-machine. Statistical-analysis was performed and the signifcance-level was set at P≤0.05. Results: After nano-bioglass addition, signifcant increases in pH values were recorded in both chemical-cured Ca(OH) 2 and light-cured one in day 1 and day 7. Similarly, adding nano-bioglass caused signifcant increase in calcium-ions-release at day 1 and further increase at day 7 in both tested materials. Meanwhile, no signifcant difference in phosphorus-ions-release was recorded after nano-bioglass addition at days 1 and 7 in chemical cured Ca(OH) 2 and at day 1 for light-cured one. SEM and EDXA showed different surface morphologies depending on the material type, addition of nano-bioglass and the immersion time. The compressive strength of the chemical-cured Ca(OH) 2 was not signifcantly affected by nano-bioglass addition. Contrary, the light-cured one showed signifcant decrease in the compressive strength after nano-bioglass addition. Conclusions: Although addition of nano-bioglass to Ca(OH) 2 liner could decrease its compressive strength, yet, it improves the ions release and hence its bioactivity. Keywords: Nano-bioglass, Calcium hydroxide, Ions release, Apatite formation, Bioactivity, Compressive strength www.gsrjournals.com Research Article Open Access Dentistry Volume 1 - Issue 1 - 14 pages Introducton Pulp capping is a procedure which consists of the placement of biocompatible materials on pulp tissue to preserve its vitality and stimulate the repair process via mineralized tissue formation 1 . It has long been rec- ognized that the traumatic exposure of the dental pulp