CAD/CAM international magazine of digital dentistry No. 4, 2016

| study fracture resistance of restorations 12 CAD/CAM 4 2016 Exploring the fracture resistance of retentive pin-retained e.max press onlays in molars Authors: Dr Les Kalman & Yasmin Joseph, Canada Abstract Retentive titanium dentinal pins have been com- bined with indirect restorations. Application of pins has been used with lithium disilicate, an indi- rect pressed ceramic restorative material, termed e.max. The objective of this study was to investi- gate the fracture resistance of pin-retained versus non pin-retained indirect e.max press restorations. Ten human extracted teeth were used for the con- trol and ten for the test group. Titanium dentinal pinswereplacedande.maxpressrestorationswere fabricated, by a commercial laboratory, and then cemented. Fracture resistance was assessed. Data was collected and results were obtained. Fracture resistance of both groups indicated no significant difference in values. An observation from testing illuminated that pin-reinforced e.max benefitted from a controlled fracture, which minimized tooth damage. The data suggests that pin-reinforced indirect e.max restorations offer no appreciable difference in fracture resistance. Further testing would be required to expand upon the sample size, explore other strength vectors and consider a clin- ical investigation. Introduction The loss of tooth structure, from disease or biome- chanical stress, requires the replacement of tooth structure through dental restoration techniques. Thismayoccureitherdirectlyorindirectly.Extensive tooth restorations typically require indirect resto- rations.1 Indirect dental restorations benefit from excellent form, function, esthetics, and strength; however, the retention of indirect restorations can prove problematic.1 This is primarily due to the variable technique-sensitive chemical bond of the restorativematerialwiththetooth.2 Thetypeofres- toration used largely depends on the magnitude of tooth destruction and dictates unique preparation design characteristics.3 Fig. 1: No pin onlay tooth preparation. Fig. 2: Pin onlay tooth preparation. Fig. 1 Fig. 2 42016

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