Resistance of All-Ceramic Crowns

Objectives: The objective of this study was to analyze full crown removal or crown fracture using two different types of cements on all ceramic crowns that had a total taper of 45 degrees when introduced to compressive loads. Methods: Ten prepared teeth were placed in water solution, and then properly cemented with self adhesive resin cement to their respective CEREC (Serona) constructed all-ceramic crown. Five teeth were cemented with Multilink Automix (Ivoclar) and the other five were cemented with SpeedCEM (Ivoclar). The all-ceramic crown specimens were then placed in a humidifier for twenty four hours. These crowns were then subject to displacement stress, which was done at 45 degrees giving a combination of shear and compression, by the INSTRON testing machine until crown fracture or full crown removal from the tooth. Results: The 45 degree compressive method proved that in most cements the bond strength surpass the compressive strength of the all-ceramic crown, and that only crown fracture occurred as opposed to full crown removal. Conclusion: The resistance of the all-ceramic crown differs in tension versus shear and compression. In a previous study, it shows that tension by the pull method yields low resistance of the crown, and that the compressive method at a 45 degree angle yields higher crown resistance. Supported by the UTHSC Dental Alumni Endowment Fund for Research