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 (20�-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/37�C/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.