A comparison of the effects of two burs on endodontic access in all-ceramic high Lucite crowns

Resistance to fracture of two all-ceramic crown materials following endodontic access

“…The authors concluded carbide burs produced more fractures and craze lines than diamond rotary cutting instruments. In another study, Haselton et al 8 quantitatively characterized damage to crowns following endodontic access. Using SEM analysis on 28 Lucite-reinforced pressed glass-ceramic crowns (IPS Empress; Ivoclar Vivadent, Amherst, NY), the authors classified the damage into 3 categories: (1) edge chipping-a disruption of the outline form; (2) visual microcrack-a crack with no separation of porcelain, and (3) fracture-a crack resulting in 2 or more parts.…”

Fracture resistance assessment of endodontically accessed hybrid ceramic crowns repaired with two different protocols

“…(26,27) Endodontic access openings through all ceramic restorations may initiate microcracks which could propagate with time and cause fracture. Considering these challenges, access openings were done with a diamond rotary cutting instrument in a high speed hand piece with heavy water spray in accordance with Sutherland et al (28) Haselton et al (29) and Oden et al (30) in order to avoid the vibration of low speed hand pieces which may produce cracks at the ceramic margins. Diamonds were the instrument of choice rather than carbide burs because they are more suited for ceramics as the mechanism of grinding leads to a smoother cut with less vibration.…”

Fracture Resistance of Pressed and Milled Lithium Disilicate Anterior Complete Coverage Restorations Following Endodontic Access Preparation

“…Ceramic systems respond differently to the creation of access openings, with all‐ceramic crowns being negatively affected when accessed. Edge chipping commonly seen around the access opening can render a restoration more prone to crack propagation …”

“…Edge chipping commonly seen around the access opening can render a restoration more prone to crack propagation. [17][18][19][20][21] The strength of lithium disilicate in particular poses distinct challenges during endodontic access. Specialized diamonds with anti-clog coatings, minimal heat generation designs, and durable brazing techniques, in combination with copious water irrigation, aim to minimize ceramic chipping and heat accumulation.…”

“…29 The substrate material of a ceramic restoration also influences its fracture resistance. 29,35,36 The elastic modulus of the substrate used in vitro needs to be close to the range reported for human dentin (15)(16)(17)(18)(19)(20), to ensure clinically relevant results. 29 In recent in vitro studies, 21,24 the elastic moduli of the substrates was different from human dentin, potentially limiting clinical validity of results.…”