Evaluation of the physical properties of an endodontic Portland cement incorporating alternative radiopacifiers used as root-end filling material.
OBJECTIVE
To investigate the physical and chemical properties of Portland cement (PC) loaded with alternative radiopacifying materials for use as root-end filling materials in a mineral trioxide aggregate (MTA)-like system.


METHODS
Portland cement loaded with barium sulphate, gold and silver/tin alloy was mixed with water, and the physical and chemical properties of the hydrated cements were evaluated. MTA and intermediate restorative material (IRM) were used as controls. The radiopacity was compared to the equivalent thickness of aluminium, and the setting time of the cements was assessed using an indentation technique. The compressive strength and the stress-strain relationship were determined at 28 days. The stress-strain relationship was determined by monitoring the strain generated when the cement was subjected to compressive load. In addition, the pH was determined in water and simulated body fluid for a period of 28 days.


RESULTS
The radiopacity of the cements using alternative radiopacifiers was comparable to MTA (P > 0.05). IRM demonstrated a higher radiopacity than all the materials tested (P < 0.05). All the cements with the exception of IRM exhibited an alkaline pH and had an extended setting time when compared to IRM. MTA had a longer setting time than the PC (P < 0.001), and its setting time was similar to the gold-loaded cement (P = 0.159). The addition of a radiopacifier retarded the setting time (P < 0.001) but did not have any effect on the compressive strength as all loaded cements had comparable strength to PC (P > 0.05). IRM was the weakest cement tested (P < 0.001). The cement loaded with gold radiopacifier had comparable strength to MTA (P = 1). The stress-strain relationship was linear for all the cements with IRM generating more strain on loading.


CONCLUSIONS
Within the parameters set in this study, bismuth oxide in MTA can be replaced by gold or silver/tin alloy. The physical, mechanical and chemical properties of the cement replaced with alternative radiopacifiers were similar and comparable to ProRoot MTA.
Department of Building and Civil Engineering, Faculty for the Built Environment, University of Malta, Msida MSD, Malta. josette.camilleri@um.edu.mt
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Camilleri
D017607:Aluminum Compounds / Q000737:chemistry; D000704:Analysis of Variance; D017610:Calcium Compounds / Q000737:chemistry; D019245:Compressive Strength; D003287:Contrast Media / Q000737:chemistry*; D003722:Dental Alloys; D003738:Dental Cements / Q000737:chemistry*; D003799:Dental Stress Analysis; D004338:Drug Combinations; D006047:Gold Alloys; D006863:Hydrogen-Ion Concentration; D008768:Methylmethacrylates / Q000737:chemistry; D010087:Oxides / Q000737:chemistry; D012184:Retrograde Obturation / Q000379:methods*; D012387:Root Canal Filling Materials / Q000737:chemistry*; D017640:Silicates / Q000737:chemistry; D012834:Silver; D018709:Statistics, Nonparametric; D014001:Tin; D015035:Zinc Oxide-Eugenol Cement / Q000737:chemistry
D017607:Aluminum Compounds; D017610:Calcium Compounds; D003287:Contrast Media; D003722:Dental Alloys; D003738:Dental Cements; D004338:Drug Combinations; D006047:Gold Alloys; D008768:Methylmethacrylates; D010087:Oxides; D012387:Root Canal Filling Materials; D017640:Silicates; D015035:Zinc Oxide-Eugenol Cement; C472247:accelerated Portland cement; C086631:mineral trioxide aggregate; D012834:Silver; C031667:IRM cement; D014001:Tin