The effect of polymerization procedure on Vickers hardness of dual-curing resin cements.
OBJECTIVE
To investigate the surface hardness (Vickers hardness, HVN) of one light-curing flowable resin composite and five dual-curing resin cements after different polymerization procedures.


METHODS
The HVN was measured with a hardness-indentation device on one light-curing flowable resin composite (Tetric EvoFlow) and five dual-curing resin cements (Panavia F2.0, SpeedCEM, RelyX Unicem Clicker, SmartCem2 and iCEM) after the resin material had been cured at constant 30 degrees C according to one of five polymerization procedures (n = 30/procedure and material): (1) 5-minute light-curing (positive control; prolonged light-curing), (2) 40-second light-curing (immediate light-curing), (3) 6-minute auto-curing (negative control; dual-curing resin cements only), (4) 6-minute auto-curing followed by 40-second light-curing (delayed light-curing), and (5) 5-second light-curing, 1-minute auto-curing and 40-second light-curing (instructions for removal of excess cement). A Kruskal Wallis test followed by pairwise Wilcoxon ranksum tests with Bonferroni-Holm adjustment was applied for each material and procedure (level of significance: alpha = 0.05).


RESULTS
For each material, Procedure 1 showed the significantly highest HVN and Procedure 3 the significantly lowest HVN. Procedure 4 showed significantly increased HVN for each material compared to Procedure 3. With Procedure 1, Panavia F2.0 and RelyX Unicem yielded significantly higher HVN than the other resin materials. With Procedure 3, no significant differences in HVN were found between Panavia F2.0, SpeedCEM and SmartCem2 which all showed significantly higher HVN than RelyX Unicem and iCEM.
Department of Preventive, Restorative and Pediatric Dentistry, School of Dental Medicine, University of Bern, Switzerland. simon.flury@zmk.unibe.ch
Simon
S
Flury
Anne
A
Peutzfeldt
Adrian
A
Lussi
D017438:Bisphenol A-Glycidyl Methacrylate / Q000737:chemistry; D002516:Ceramics / Q000737:chemistry; D003188:Composite Resins / Q000737:chemistry; D003764:Dental Materials / Q000737:chemistry; D006244:Hardness; D006801:Humans; D055115:Light-Curing of Dental Adhesives; D008422:Materials Testing; D008689:Methacrylates / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D011093:Polyethylene Terephthalates / Q000737:chemistry; D058105:Polymerization; D011109:Polymethacrylic Acids / Q000737:chemistry; D011140:Polyurethanes / Q000737:chemistry; D019279:Resin Cements / Q000737:chemistry*; D013696:Temperature; D013997:Time Factors
D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; C438843:Panavia-Fluoro; D011093:Polyethylene Terephthalates; D011109:Polymethacrylic Acids; D011140:Polyurethanes; C483701:Rely X Unicem; D019279:Resin Cements; C501891:Tetric EvoCeram; C029824:urethane dimethacrylate luting resin; C020946:triethylene glycol dimethacrylate; C025539:Lavsan; D011092:Polyethylene Glycols; D017438:Bisphenol A-Glycidyl Methacrylate; C069749:methacryloyloxydecyl dihydrogen phosphate