The effect of resin coating on the shear punch strength of restorative glass ionomer cements.
OBJECTIVE
The aim of the current study was to examine the shear punch strength (SPS) of high-strength glass ionomer cements (HSGICs) in relation to coating applications and duration of coating.


METHODS
I-Ninety specimens each of Fuji IX GP Fast (FIX Fast), Ionofil Molar AC (IM), Riva Self Cure (R) and Ketac Molar (KM) were prepared and divided into uncoated and coated groups, sub-divided into three sub-groups and incubated for 24 h, 1 week or 8 weeks (distilled water, 37 °C) before SPS. II-Ninety specimens each of uncoated and coated Fuji IX GP Extra were similarly prepared, divided into six sub-groups and incubated for 2 h, 24 h, 1 week, 1 month, 2 months or 3 months (artificial saliva, 37 °C) before SPS. Another 90 specimens were coated for 2 h, 24 h, 1 week, 1 month or 2 months, after which the coating was removed. Specimens were re-incubated in artificial saliva until the end of the 3-month period and then subjected to SPS.


RESULTS
None of the materials gained extra strength when coated. Uncoated KM, IM (at all times) and FIX Fast (at 24 h) were stronger. Fuji IX GP Extra achieved 11.5 MPa after 2 h, which increased to 56.7 MPa after 24 h. The highest strength after 3 months was achieved when the coating was retained for 2 h (71.7 MPa).


CONCLUSIONS
A resin coating will not positively affect the SPS of HSGICs.


CONCLUSIONS
There is no need to protect HSGICs from water to gain extra strength unless the coating is retained for 2 h.
Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel. rafipilo@gmail.com.
Raphael
R
Pilo
Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel.
Ariel
A
Ben-Amar
School of Dental Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel.
Anna
A
Barnea
School of Dental Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel.
Yaron
Y
Blasbalg
Department of Oral Rehabilitation, The Maurice and Gabriela Goldschleger School of Dental Medicine, Tel Aviv University, Tel Aviv, 6997801, Israel.
Shifra
S
Levartovsky
D020099:Coated Materials, Biocompatible; D003799:Dental Stress Analysis; D005899:Glass Ionomer Cements / Q000737:chemistry*; D008422:Materials Testing; D012117:Resins, Synthetic / Q000737:chemistry*; D012464:Saliva, Artificial; D033081:Shear Strength; D013499:Surface Properties; D014867:Water
D020099:Coated Materials, Biocompatible; D005899:Glass Ionomer Cements; D012117:Resins, Synthetic; D012464:Saliva, Artificial; C110713:fuji IX; C541507:ionofil U; C110712:ketac-molar; D014867:Water
Artificial saliva; Auto-cured glass ionomer; Distilled water; Resin coating; Shear punch strength