Priming and bonding metal, ceramic and polycarbonate brackets

Figures & data

Table 1. Materials used in the study.

Materials	Manufacturer	Lot No.	Contents	Wt%
Transbond XT Light Cure Adhesive	3M Unitek (Monrovia, CA, USA)	N765918	Silane treated quartz BIS-GMA EBPADMA Silane treated silica Diphnyliodonium hexafluorophosphate	70–80* 10–20* 5–10* <2* <0.2*
Transbond XT Primer	3M Unitek (Monrovia, CA, USA)	N762529	BIS-GMA TEGDMA Triphenylantimony 4-(dimethylamino)-benzeneethanol DL-camphorquinone Hydroquinone	45–55* 45–55* <1* <0.5* <0.3* <0.03*
Etching Gel	3M Unitek (Monrovia, CA, USA)	626002	Water Phosphoric acid Amorphous silica	55–65* 30–40* 5–10*
RelyX™ Ceramic Primer	3M™ ESPE™, (St. Paul, MN, USA)	N759704	Ethyl alcohol Water Methacryloxypropyltrimethoxysilane	70–80* 20–30* <2*
Monobond Plus	Ivoclar Vivadent, (Schaan, Liechtenstein)	V12120	Ethanol 3-trimethoxysilylpropylmethacrylate Methacrylated phosphoric acid ester	50–100 ≤2.5 ≤2.5
Adper™ Scotchbond™ Multi-Purpose Adhesive	3M™ ESPE™, (St. Paul, MN, USA)	N735458	BIS-GMA 2-hydroxyethyl methacrylate (HEMA) Triphenylantimony	60–70* 30–40* <0.5*
GC Composite Primer	GC, (Hongo, Bunkyo-ku, Tokyo, Japan)	1604061	2-hydroxyethyl methacrylate (HEMA) Tetrahydrofurfuryl methacrylate Urethane dimethacrylate (UDMA)	30–60* 10–30* 10–30*
Ortomat Minimat	Ormco, (Glendora, CA, USA)	15M378M	Stainless steel
Inspire ICE	Ormco, (Glendora, CA, USA)	081650467	Single crystal aluminum oxide Zirconium oxide
Spirit MB	Ormco, (Glendora, CA, USA)	081612367	Filler reinforced polycarbonate

BIS-GMA indicates bisphenol-A-diglycidyl ether dimethacrylate, EBPADMA bisphenol-A-bis(2-hydroxyethyl ether) dimethacrylate, TEGDMA triethylene glycol dimethacrylate.

Methacryloxypropyltrimethoxysilane and 3-trimethoxysilylpropylmethacrylate are different names used by the manufacturers for the same compound.

* The specific chemical identity and/or exact percentage (concentration) of this composition has been withheld as a trade secret.

Table 2. Test groups, primers and the primer applying procedure.

Bracket type	Group name	Primer (applied to the base of the bracket)	Primer applying procedure
Metal	met1	No Primer	–
	met2	Silane (RelyX™ Ceramic Primer)	Gentle air drying
	met3	Universal Primer (Monobond Plus)	Gentle air drying
Ceramic	cer1	No Primer	–
	cer2	Silane (RelyX™ Ceramic Primer)	Gentle air drying
	cer3	Universal Primer (Monobond Plus)	Gentle air drying
Polycarbonate	pol1	No Primer	–
	pol2	Adhesive Resin (Adper™ Scotchbond™ Multi-Purpose Adhesive)	Gentle air drying, 10s light curing
	pol3	Composite Primer (GC Composite Primer)	Gentle air drying, 20s light curing

Table 3. Adhesive remnant index (ARI), definition of scores.

Score	Definition
0	No adhesive remained on enamel
1	Less than 50% of adhesive remained on enamel
2	More than 50% of adhesive remained on enamel
3	All adhesive remained on enamel

Figure 1. Scanning electron microscope images of the bracket bases. (1, 2) metal bracket with a mesh base design, magnification X18 and X100; (3, 4) ceramic bracket with small spheres on the base, magnification X18 and X100; (4, 5) polycarbonate bracket with large protuberances on the base, magnification X18 and X100.

Figure 2. Surface contour analysis of the metal bracket, a close-up of the mesh on the bracket base. The overall difference between the highest and the lowest point of the base is approximately 125 µm.

Figure 3. Surface contour analysis of the ceramic bracket, a close-up of the small spheres on the bracket base. The contour of the spheres accounts for the artifact around the edges of the spheres (the spikes). The overall difference between the highest and the lowest point of the base is approximately 50 µm.

Figure 4. Surface contour analysis of the polycarbonate bracket, a close-up of one of the square protuberances on the bracket base. The overall difference between the highest and the lowest point of the base is approximately 150 µm.

Figure 5. Bond Strength (MPa) of test groups, error bars represent standard deviation, the different letters above the columns represent statistically significant differences between groups (p < .05).

Figure 6. ARI scores of the test groups. See Table 3 for ARI score description.

Figure 7. Examples of ARI scores. 1–5 light microscope images. 1 = ARI score 3, 2 = ARI score 2, 3 = ARI score 1, 4 = ARI score 0, 5 = ARI score 1 with enamel fracture, 6 = SEM image of the same sample as picture 5: adhesive remnants and fractured enamel, magnification X25.