International Journal of Health Sciences and Research Vol.10; Issue: 7; July 2020 Website: www.ijhsr.org Original Research Article ISSN: 2249-9571 Modification of Portland Cement Properties using Glycerin Manar Abu-Nawarega, Ahmed Zidanb aKing Abdulaziz University, Faculty of Dentistry, Jeddah, Saudi Arabia and Faculty of Oral and Dental Medicine, Cairo University, Cairo, Egypt. bFaculty of Dentistry, Umm Al-Qura University, Mekkah, Saudi Arabia and Faculty of Dentistry, October University for Modern Sciences and Arts (MSA), Cairo, Egypt. Corresponding Author: Manar Abu-Nawareg ABSTRACT Objective: The aim of this study was to evaluate the influence of 15% glycerin on the physico- mechanical properties of Portland cement, in an attempt to apply it to mineral trioxide aggregate (MTA). Materials and Methods: Portland cement, mixed with 10 wt% calcium chloride (CaCl2) as an accelerator, was used in this study. The resultant powder was either mixed with distilled water (PC) or 15% glycerin liquid (PCG). The compressive strength, setting time, cohesion time and anti-washout time of the two cements PC and PCG were tested and compared to those obtained by Biodentine (BD). Furthermore, the internal microstructure of the three tested cements (BD, PC and PCG) was evaluated by scanning electron microscope (SEM). Results: BD provided the highest compressive strength followed by PCG then PC. The highest setting and cohesion times were exhibited by PC while there was no significant difference between BD and PCG. Regarding the anti-washout time test, PC exhibited the highest value followed by BD while the lowest value was provided by PCG. Conclusions: Addition of 15% glycerin to Portland cement has improved the setting time, the cohesiveness and the anti-washout ability of the cement with subsequent improvement in the handling properties as well as increasing its compressive strength. This trial is considered to be a successful step which should be performed on Portland cement twin; the MTA. Keywords: Portland Cement, Glycerin, Compressive Strength, Setting Time, Anti wash-out ability, SEM INTRODUCTION hydroxide. Thus, the resultant calcium Many years ago, the introduction of hydroxide is responsible for the alkaline mineral trioxide aggregate (MTA), a medium of the cement. Besides, the derivative of Portland cement, in the dental cement’s ability to set in presence of water therapy has received a great attention. This or blood (i.e. requires moisture to set) is mainly due to its unique biological makes its use in contact with a moist tissue, activity, as it has antibacterial and anti- such as the pulp, relatively easy. [1,2] inflammatory properties. This is primarily MTA has proven to be a material due to the increase in the pH value (12.5) of with several potential clinical applications. the surrounding environment resulting from This is mainly due to its biocompatibility the reaction of tricalcium silicate, the main and its ability to induce mineralization constituent of both MTA and Portland which promotes dental pulp and peri- cement, with water to produce calcium radicular tissue regeneration. Furthermore, it International Journal of Health Sciences and Research (www.ijhsr.org) 168 Vol.10; Issue: 7; July 2020 Manar Abu-Nawareg et.al. Modification of portland cement properties using glycerin has a superior sealing property owing to its composition and the low price of Portland setting expansion. [2-4] These attractive cement encourage trials which aim at properties have encouraged the use of MTA modifying both physical and mechanical as a potential medicament for pulpotomy properties of Portland cement as a step to be procedures, capping of pulps with reversible followed by their application on MTA. pulpitis, apexification, repair of root In Portland cement industry, perforation and coronal barrier. [5,6] This is attempts were performed to incorporate in addition to its successful use in the repair additives as methylcellulose or glycerin as of external root resorption and obturation of anti-washout ingredients, in combination retained primary teeth. [7] with calcium chloride as an accelerator, to On the other hand, the main increase the cohesiveness and plasticity of disadvantages of MTA are its extended the material, making it easier to handle and setting time and difficult handling. This is accelerating its setting time. [8,14,16-18] mainly due to its granular consistency, Therefore, the aim of this study was to initial looseness, tendency to washout in evaluate the influence of 15% glycerin on presence of excess moisture and, once the the physico-mechanical properties of mixture starts to dry, it loses its Portland cement including; compressive cohesiveness and becomes difficult to strength, setting time, cohesion time and handle. This is in addition to the limitation anti-washout time in an attempt to apply it in achieving high strengths, which lies in the to mineral trioxide aggregate (MTA). inherent porosity of the material. [1,8,9] Since MTA is very similar in composition to MATERIALS AND METHODS Portland cement, they both appear to have White Portland cement powder was the same advantages and disadvantages. [9] used in this study and was mixed with 10 wt A series of innovative calcium % calcium chloride (CaCl2) powder as an silicates, based on Portland cement, have accelerator, i.e. 0.9 gm white Portland been recently developed to get use of the cement powder was mixed with 0.1 gm alkaline medium provided during its setting. CaCl2using an electronic balance with four Biodentine™ is a new calcium silicate digits precision (Scaltec Instruments GmbH based cement, similar to MTA, where Rudolf-Heiligenstadt, Germany).The tricalcium silicate is found as the main formulated powder was mechanically mixed cementitious component. [10-12] Therefore, in a vibrator (Jenway 1010 vibrator, Serial Biodentine exhibits physical and chemical #: 2273, Dunmow, Essex, U.K.) for 5 properties similar to those described for minutes to ensure proper distribution and Portland cement derivatives. [11] However, intermingling of the powder particles. The according to the manufacturer, it is resultant powder was divided into two characterized by obviously shorter setting groups; in the first group it was mixed with time and much more user-friendliness. distilled water to form "PC" paste while in Biodentine has been developed and the second group it was mixed with 15% produced aiming to bring together the high glycerin liquid to form "PCG" paste. These biocompatibility and bioactivity of calcium two cements "PC" and "PCG" were silicates with enhanced physical properties, compared to the commercially available thus offering a homogeneous and dense Biodentine (BD). product with maximized strength. [10,12-14] For the PC group, the powder/ liquid On the other hand, the highly ratio was 3: 1 (according to the successful results and the wide spread of the manufacturer’s recommendations for MTA) commercially available mineral trioxide i.e. for every 1gm powder, 0.33 ml distilled aggregate (MTA) during the last few years water was used. On the other hand, for the necessitate carrying out trials to improve its PCG group, 15% glycerin liquid was mixed main drawbacks. [8,15] The close similarity in with the powder of Portland cement at International Journal of Health Sciences and Research (www.ijhsr.org) 169 Vol.10; Issue: 7; July 2020 Manar Abu-Nawareg et.al. Modification of portland cement properties using glycerin different weight ratios till attaining an condenser to minimize air entrapment. appropriate smooth and homogenous Moulds were overfilled and the excess consistency employing the standardized one material was removed by using a glass slide inch string method. [19] A 2:1 powder/ liquid to ensure properly leveled specimens. After ratio was selected for the PCG group i.e. for setting, the tops and bottoms of the every 1 gm Portland cement powder, 0.5 ml specimens were ground, until flush with the glycerin liquid was used. moulds, using a series of silicon-carbide The 15% glycerin liquid means that abrasive sheets; # 800,# 1000 and # 1200 every 100 ml of the liquid is formed of 15 successively to obtain flat and smooth ml glycerin and 85 ml distilled water. This surfaces. percentage was selected according to a pilot The specimens were removed from study based on extensive preliminary the Teflon moulds and examined for voids mixtures and tests. In the pilot study, the and irregularities. If voids were detected, the criteria used for selecting the appropriate specimen was discarded. The specimens glycerin percentage, to be mixed with were then stored in distilled water for 24 Portland cement powder containing10 % hours at 37±1°C in an incubator (Foc CaCl2, was done by evaluating the setting Incubator, Japan). time and compressive strength of each At the time of test conduction, each tested sample. For the BD group, specimen was vertically mounted in a BiodentineTM was mixed according to the computer controlled universal testing manufacturer’s directions. The materials machine (LRX plus, LC 5 KN. Lloyd used in this study are detailed in table (I). Instruments Ltd., Fareham, U.K.) with a The tested materials (BD, PC, and PCG) load-cell of 5 KN and data were recorded were evaluated regarding the following using computer software (Nexygen-MT; properties: Lloyd Instruments). Then, each specimen was statically loaded (in a compression 1. Compressive strength test: manner) along its long axis at a crosshead Ten specimens of each tested speed of 0.5 mm/min until failure. The material (BD, PC, and PCG) were prepared failure load was recorded in Newtons (N). according to ISO Standard 9917: 1991 and Then, the compressive strength in Mega American National Standards Institute / Pascal (MPa) was calculated using the American Dental Association (ANSI/ADA) following formula; [9,20] Specification No. 96 for water-based dental [20,21] cements. A cylindrical split Teflon mould of Where; diameter 4 mm and height 8 mm was used δc: Compressive Strength in Mega Pascal for specimens preparation.