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KMID : 1023820200120040181
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The Journal of Advanced Prosthodontics
2020 Volume.12 No. 4 p.181 ~ p.188
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Effect of core design on fracture resistance of zirconia-lithium disilicate anterior bilayered crowns
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Ko Kyung-Ho
Park Chan-Jin
Cho Lee-Ra
Huh Yoon-Hyuk
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Abstract
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PURPOSE: The effect of core design on the fracture resistance of zirconia-lithium disilicate (LS2) bilayered crowns for anterior teeth is evaluated by comparing with that of metal-ceramic crowns.
MATERIALS AND METHODS: Forty customized titanium abutments for maxillary central incisor were prepared. Each group of 10 units was constructed using the same veneer form of designs A and B, which covered labial surface to approximately one third of the incisal and cervical palatal surface, respectively. LS2 pressed-on-zirconia (POZ) and porcelain-fused-to-metal (PFM) crowns were divided into “POZ_A,” “POZ_B,” “PFM_A,” and “PFM_B” groups, and 6000 thermal cycles (5/55℃) were performed after 24 h storage in distilled water at 37℃. All specimens were prepared using a single type of self-adhesive resin cement. The fracture resistance was measured using a universal testing machine. Failure mode and elemental analyses of the bonding interface were performed. The data were analyzed using Welch's t-test and the Games-Howell exact test.
RESULTS: The PFM_B (1376. 8 ± 93.3 N) group demonstrated significantly higher fracture strength than the PFM_A (915.8 ± 206.3 N) and POZ_B (963.8 ± 316.2 N) groups (P<.05). There was no statistically significant difference in fracture resistance between the POZ_A (1184.4 ± 319.6 N) and POZ_B groups (P>.05). Regardless of the design differences of the zirconia cores, fractures involving cores occurred in all specimens of the POZ groups.
CONCLUSION: The bilayered anterior POZ crowns showed different fracture resistance and fracture pattern according to the core design compared to PFM.
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KEYWORD
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Lithium disilicate, Zirconia, Metal-ceramic crown, Fracture resistance
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