Selected physical properties of new resin-modified glass ionomer luting cements.
BACKGROUND
Two resin-modified glass ionomer (RMGI)-based luting agents have been recently marketed without independent reports of their physical properties.


OBJECTIVE
The purpose of this in vitro study was to evaluate selected physical properties of 2 newly marketed RMGI luting agents and compare the findings with traditional materials.


METHODS
Specimens (N=12) of Nexus RMGI, UltraCem, GC Fuji Cem 2, and RelyX Luting Plus were fabricated using standardized molds for flexural strength and fracture toughness according to manufacturer recommendations and stored in physiologic phosphate-buffered saline solution at 37°C until testing. Specimens were tested at 1 and 24 hours, 1 week, and 1 month. Mean values for flexural strength, flexural modulus, flexural toughness, and fracture toughness were determined. Additionally, film thickness (N=12) for each material was determined following Amerian National Standards Association/American Dental Association (ANSI/ADA) specifications. Mean results were analyzed with Kruskal-Wallis and Mann-Whitney U tests (α=.05).


RESULTS
All luting agents exhibited a similar film thickness that met ANSI/ADA requirements for aqueous-based luting agents. Nexus RMGI surprisingly demonstrated significantly greater flexural strength and fracture toughness at 1 hour, which decreased significantly at 24 hours, making it similar to the other materials evaluated. All materials had similar flexural strength values at 7 days.


CONCLUSIONS
Physical property performance was material dependent. Nexus RMGI demonstrated greater early physical properties that were significantly less at 24 hours. UltraCem, GC Fuji Cem 2, and RelyX Luting Plus demonstrated the increasing physical property development that is normally associated with polyalkenoate-based systems.
General Dental Officer, 52 Dental Squadron/SGD, Spangdahlem AFB, Germany.
Jason R
JR
Garner
Director, AEGD-2, USAF Dental Postgraduate School, Keesler AFB, Miss.
Michael N
MN
Wajdowicz
Deputy Director, AEGD-2, USAF Dental Postgraduate School, Keesler AFB, Miss.
Nicholas B
NB
DuVall
Director, Graduate Dental Research, USAF Dental Postgraduate School, Keesler AFB, Miss. Electronic address: Howard.roberts@us.af.mil.
Howard W
HW
Roberts
D003188:Composite Resins / Q000627:therapeutic use; D003738:Dental Cements; D003799:Dental Stress Analysis; D005899:Glass Ionomer Cements / Q000737:chemistry* / Q000627:therapeutic use; D066298:In Vitro Techniques; D019279:Resin Cements / Q000737:chemistry; D013718:Tensile Strength
D003188:Composite Resins; D003738:Dental Cements; D005899:Glass Ionomer Cements; C433206:Nexus; D019279:Resin Cements; C084550:Vitremer