Remineralizing amorphous calcium phosphate based composite resins: the influence of inert fillers on monomer conversion, polymerization shrinkage, and microhardness.
OBJECTIVE
To determine if the addition of inert fillers to a bioactive dental restorative composite material affects its degree of conversion (DC), polymerization shrinkage (PS), and microhardness (HV).


METHODS
Three amorphous calcium phosphate (ACP)-based composite resins: without added fillers (0-ACP), with 10% of barium-glass fillers (Ba-ACP), and with 10% of silica fillers (Si-ACP), as well as commercial control (Ceram•X, Dentsply DeTrey) were tested in laboratory conditions. The amount of ACP (40%) and the composition of the resin mixture (based on ethoxylated bisphenol A dimethacrylate) was the same for all ACP materials. Fourier transform infrared spectroscopy was used to determine the DC (n=40), 20 min and 72 h after polymerization. Linear PS and Vickers microhardness (n=40) were also evaluated. The results were analyzed by paired samples t test, ANOVA, and one-way repeated measures ANOVA with Student-Newman-Keuls or Tukey's post-hoc test (P=0.05).


RESULTS
The addition of barium fillers significantly increased the DC (20 min) (75.84±0.62%) in comparison to 0-ACP (73.92±3.08%), but the addition of silica fillers lowered the DC (71.00±0.57%). Ceram•X had the lowest DC (54.93±1.00%) and linear PS (1.01±0.24%) but the highest HV (20.73±2.09). PS was significantly reduced (P<0.010) in both Ba-ACP (1.13±0.25%) and Si-ACP (1.17±0.19%) compared to 0-ACP (1.43±0.21%). HV was significantly higher in Si-ACP (12.82±1.30) than in 0-ACP (10.54±0.86) and Ba-ACP (10.75±0.62) (P<0.010).


CONCLUSIONS
Incorporation of inert fillers to bioactive remineralizing composites enhanced their physical-mechanical performance in laboratory conditions. Both added fillers reduced the PS while maintaining high levels of the DC. Silica fillers additionally moderately improved the HV of ACP composites.
Danijela Marović, Department of Endodontics and Restorative Dentistry, School of Dental Medicine, University of Zagreb, Gundulićeva 5, 10 000 Zagreb, Croatia, marovic@sfzg.hr.
Danijela
D
Marović
Kristina
K
Šariri
Nazif
N
Demoli
Mira
M
Ristić
Karl-Anton
KA
Hiller
Drago
D
Škrtić
Martin
M
Rosentritt
Gottfried
G
Schmalz
Zrinka
Z
Tarle
D017609:Barium Compounds / Q000737:chemistry; D002130:Calcium Phosphates / Q000737:chemistry*; D003188:Composite Resins / Q000737:chemistry*; D003764:Dental Materials / Q000737:chemistry*; D006801:Humans; D008689:Methacrylates / Q000737:chemistry; D058105:Polymerization; D012822:Silicon Dioxide / Q000737:chemistry
D017609:Barium Compounds; D002130:Calcium Phosphates; C520091:CeramX; D003188:Composite Resins; D003764:Dental Materials; D008689:Methacrylates; C519480:amorphous calcium phosphate; C102738:barium glass filler; C074277:ethoxylated bis-phenol A dimethacrylate; D012822:Silicon Dioxide