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Fracture load and marginal fit of shrinkage‐free ZrSiO 4 all‐ceramic crowns after chewing simulation
Author(s) -
OKUTAN M.,
HEYDECKE G.,
BUTZ F.,
STRUB J. R.
Publication year - 2006
Publication title -
journal of oral rehabilitation
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.991
H-Index - 93
eISSN - 1365-2842
pISSN - 0305-182X
DOI - 10.1111/j.1365-2842.2006.01637.x
Subject(s) - cementation (geology) , molar , dentistry , materials science , fracture (geology) , glass ionomer cement , shrinkage , orthodontics , ceramic , composite material , cement , medicine
summary The aim of this in vitro study was to evaluate the fracture load and marginal accuracy of crowns made from a shrinkage‐free ZrSiO 4 ceramic cemented with glass–ionomer or composite cement after chewing simulation. Thirty‐two human mandibular molars were randomly divided into two groups. All teeth were prepared for and restored with shrinkage‐free ZrSiO 4 ceramic crowns (Everest HPC®, KaVo). The crowns of group A ( N = 16) were luted to the teeth using KetacCem® and group B ( N = 16) were adhesively cemented using Panavia®21EX. Measurements of the marginal accuracy before and after cementation were made using replicas and an image analysis system. All specimens were exposed to 1·2 million cycles of thermo‐mechanical fatigue in a chewing simulator. Surviving specimens were subsequently loaded until fracture in a static testing device. Fracture loads (N) were recorded. All specimens survived chewing simulation. The mean fracture loads (±s.d.) were Group A, 1622 N (±433); group B, 1957 N (±806). There was no significant difference between the two groups ( P > 0·05). The marginal gap values before cementation were (mean ± s.d.): Group A, 32·7 μ m (±6·8); group B, 33·0 μ m (±6·7).The mean marginal gap values after cementation were (±s.d.): Group A, 44·6 μ m (±6·7); group B, 46·6 μ m (±7·7). The marginal openings were significantly higher after cementation for both groups ( P < 0·05). All test groups demonstrated fracture load and marginal accuracy values within the range of clinical acceptability.