Surface Treatment Of Nanozirconia Fillers To Strengthen Dental Bisphenol A–Glycidyl Methacrylate–Based Resin Composites

Figures & data

Table 1 Contents Of Resin Composites (wt%)

Group	Bis-GMA	TEGDMA	CQ	EDMAB	Silica	ZrO2
1	27	11.5	0.5	1	57.5	2.5/MDP-ZrO2
2	27	11.5	0.5	1	57.5	2.5/MDP-Zr(OH)4–ZrO2
3	27	11.5	0.5	1	57.5	2.5/ZrO2
4	27	11.5	0.5	1	55	5/MDP-ZrO2
5	27	11.5	0.5	1	55	5/MDP-Zr(OH)4–ZrO2
6	27	11.5	0.5	1	55	5/ZrO2
7	27	11.5	0.5	1	52.5	7.5/MDP-ZrO2
8	27	11.5	0.5	1	52.5	7.5/MDP-Zr(OH)4–ZrO2
9	27	11.5	0.5	1	52.5	7.5/ZrO2
Control	27	11.5	0.5	1	60	0

Notes: MDP-ZrO₂, MDP-conditioned zirconia fillers; MDP-Zr(OH)₄–ZrO₂, MDP-conditioned, Zr(OH)₄-coated zirconia fillers.

Abbreviations: Bis-GMA, bisphenol A glycidyl dimethacrylate; TEGDMA, triethylene glycol dimethacrylate; CQ, camphorquinon; EDMAB, ethyl 4-dimethylaminobenzoate; MDP, 10-methacryloyloxydecyl dihydrogen phosphate; ZrO₂, zirconia.

Figure 1 Transmission electron micrograph (TEM) and electron diffraction pattern.

Notes: Untreated zirconia fillers (A–C) and zirconia fillers coated with different concentrations of Zr(OH)₄ by adding 2 mmol/L (D–F), 5 mmol/L (G–I), 10 mmol/L (J–L), 0.5 mmol/L (M), and 100 mmol/L (N) zirconium chloride.

Table 2 Binding Energy Of O_C–O, O_Zr–O–P, O_Zr–O–Zr, O_OH– And Relative Percentages Of Zr–O–P Bond

	Bindingenergy (eV)				Percentage Zr–O–P
	C–O	OH–	Zr–O–P	Zr–O–Zr
Untreated ZrO2	532.8	532.4	—	529.5	—
MDP-ZrO2	533.3	532.6	531.7	530	35.89%
MDP-Zr(OH)4–ZrO2	533.2	532.6	531.7	529.9	52.93%

Notes: MDP-ZrO₂, resin composites with MDP-conditioned zirconia fillers; MDP-Zr(OH)₄/ZrO₂, resin composites with MDP-conditioned, Zr(OH)₄-coated zirconia fillers; Percentage of each peak was calculated from the relative peak area in the O1s narrow scan XPS spectrum.

Figure 2 X-ray photoelectron spectra.

Notes: (A) Wide-scan X-ray photoelectron spectra; (B) narrow-scan O1s spectra of untreated zirconia particles; (C) MDP-conditioned zirconia particles; (D) MDP-conditioned Zr(OH)₄-coated zirconia particle; I (O_C–O), II (O_OH–), III (O_Zr–O–P), IV (O_Zr–O–Zr), V(O_OH–) represent the different deconvoluted peaks within the main peak.

Figure 3 NMR spectra.

Notes: (A) ¹H MAS NMR spectrum of MDP-conditioned zirconia particles; (B) ³¹P MAS NMR spectrum of MDP-conditioned zirconia particles; (C) curve-fitting analysis results of ³¹P MAS NMR spectrum of MDP-conditioned zirconia particles; (D) ¹H MAS NMR spectrum of MDP-conditioned, Zr(OH)₄-coated zirconia particles; (E) ³¹P MAS NMR spectrum of MDP-conditioned Zr(OH)₄-coated zirconia particles; (F) curve-fitting analysis results of ³¹P MAS NMR spectrum of MDP-conditioned Zr(OH)₄-coated zirconia particles.

Figure 4 Mean and SD three-point bending strength values of different resin composites groups.

Notes: Letter superscripts (a–e) above columns indicate no significant difference between groups.

Table 3 Three-Point Bending Strength And Parameters Of Different Resin Composites

Zirconia Fillers, wt%	Surface Treatment Of Zirconia Fillers	σθ, Mean (MPa)	Weibull Modulus
0	Control	87.668^a	12.82
2.5%	Untreated	94.058^b	13.53
5.0%	Untreated	84.532^a,c	11.59
7.5%	Untreated	80.965^c	11.955
2.5%	MDP-ZrO2	95.195^b,d	13.055
5.0%	MDP-ZrO2	97.902^b,d	11.71
7.5%	MDP-ZrO2	92.135^a,b	16.395
2.5%	MDP-Zr(OH)4–ZrO2	95.262^b,d	13.759
5.0%	MDP-Zr(OH)4–ZrO2	105.956^e	13.17
7.5%	MDP-Zr(OH)4–ZrO2	100.354^d,e	11.83

Notes: MDP-ZrO₂, resin composites with MDP-conditioned zirconia fillers; MDP-Zr(OH)₄–ZrO₂, resin composites with MDP-conditioned Zr(OH)₄-coated zirconia fillers; letter superscripts (a-e) indicate no significant difference between groups (P>0.05).

Figure 5 Weibull distribution plot with 95% confidence intervals of different resin composites.

Notes: (A) Uniform silica fillers; (B) 2.5% untreated zirconia; (C) 5 wt% untreated zirconia; (D) 7.5 wt% untreated zirconia; (E) 2.5 wt% MDP-conditioned zirconia fillers; (F) 5 wt% MDP-conditioned zirconia fillers; (G) 7.5 wt% MDP-conditioned zirconia fillers; (H) 2.5 wt% MDP-conditioned Zr(OH)₄-coated zirconia fillers; (I) 5 wt% MDP-conditioned Zr(OH)₄-coated zirconia fillers; (J) 7.5 wt% MDP-conditioned Zr(OH)₄-coated zirconia fillers.

Table 4 Vickers Hardness Of Different Resin Composites

Zirconia Fillers, wt%	Surface Treatment Of Zirconia Fillers	Mean	SD
0	Control	43.02^a,b	1.208
2.5%	Untreated	44.32^b,c	1.687
5.0%	Untreated	44.16^b,c	1.542
7.5%	Untreated	45.6^c,d,e	1.493
2.5%	MDP-ZrO2	42.94^a,b	1.428
5.0%	MDP-ZrO2	44.16^b,d	1.542
7.5%	MDP-ZrO2	43.42^b	0.857
2.5%	MDP-Zr(OH)4–ZrO2	46.68^e	2.093
5.0%	MDP-Zr(OH)4–ZrO2	41.12^a	1.125
7.5%	MDP-Zr(OH)4–ZrO2	42.34^a,b	0.845

Notes: MDP-ZrO₂, resin composites with MDP-conditioned zirconia fillers; MDP-Zr(OH)₄–ZrO₂, resin composites with MDP-conditioned, Zr(OH)₄-coated zirconia fillers; letter superscripts (a-e) indicate no significant difference between groups (P>0.05).

Figure 6 Mean and SD translucency parameter (TP) values of different resin composites groups.

Notes: Letter superscripts (a–d) above columns indicate no significant difference between groups.