CAD-CAM ceramic crown retention of resin cements

Objectives: To measure retention of CAD-CAM e.max (Ivoclar Vivadent) and Lava (3M-ESPE) crowns using three resin luting agents with and without surface priming.

Methods: Extracted molars (n=10) were embedded in PVC cylinders with acrylic resin and placed into a lathe to produce a uniform crown preparation (20ș-taper). Following the orientation groove placement(69L bur), preparations were scanned using CEREC 3D/Sirona (e.max crowns) and LAVA COS/3M ESPE (LAVA crowns).  A CAD-CAM Milling Machine produced crowns. Preparations were imaged with digital microscope (Keyence/VHX-600) at 20X magnification and the surface area of each preparation calculated.  The bonding area was used to calculate bond strength by dividing the failure load with bonded surface area. Crowns were cemented using temporary cement (RelyX TempE/3M ESPE), stored (distilled water/37șC/7days), cleaned, sandblasted (Al₂O₃ /50”/35psi/10sec),primed and cemented(table). Specimens were stored (distilled water/37°C/24h) before debonding in tension at a cross-head speed of 5mm/min (INSTRON Model/5565). Data were compared with 2-way ANOVA and Tukey-Kramer post-hoc test(p=0.05).

Results: (Mean±SD)

Experimental Groups Parkell		e.max			Zirconia(LAVA)
		Force(N)		Stress(MPa)	Force(N)	Stress(MPa)
C&B Metabond	Primer	649.9±270	5.4±2		479.6±150	3.93±1.2
	No-Primer	183.3±66	1.8±0.6		397.7±181	3.47±1
	Metal-Primer				423.1±143	3.36±1
SEcure	Primer	459.6±155	3.8±1		353.79±166	2.63±1
	No-Primer	194.9±91	1.70±0.8		350.37±151	2.56±1
	Metal-Primer				390.71±184	3.11±1
Brush&Bond/Secure	Primer	441.7±181	3.9±2		556.64±177	4.16±1
	No-Primer	163.3±70	1.4±0.6		505.69±201	3.91±1
	Metal-Primer				509.19±222	3.71±1
Brush&Bond/Hyperfil	Primer	485.7±140	4±1		541.46±137	3.98±1
	No-Primer	138.5±77	1.3±0.7		267.09±124	1.90±0.7
	Metal-Primer				359.25±159	2.49±0.9

Conclusion:

e.max: Groups bonded with primer produced higher retention compared to no primer groups (p<.05).

Zirconia(LAVA):

Load Failure: No significant difference (p>0.05) was observed among groups except Brush&Bond/Hyperfil/(No Primer and Metal Primer), Brush&Bond/(Hyperfil/No Primer and Secure /Metal Primer), Brush&Bond/(Hyperfil/No Primer and Secure/Primer).

Stress: No significant difference (p>0.05) was observed among groups except C&B Metabond/(No Primer;Primer) and Brush&Bond/Hyperfil/No primer, Brush&Bond/Hyperfil/(No Primer and Primer), Brush&Bond/(Hyperfil and Secure)/(No Primer and Primer) showed significance. Supported in part  by a grant from Parkell.