Resistance of three new esthetic post-and-core systems to compressive loading.
BACKGROUND
Despite their esthetic properties, the fracture resistance of newly introduced esthetic post-and-core systems has not been studied, restricting clinical use.


OBJECTIVE
The purpose of this study was to determine and compare the fracture resistances of 3 recently introduced esthetic post-and-core systems with a cast metal post and core using a clinically related test method.


METHODS
Forty recently extracted caries-free maxillary central incisors were selected, sectioned, and their roots endodontically treated. The roots were then embedded in acrylic resin blocks and assigned to 4 experimental groups (n = 10). The cast metal (Wiron 99) post-and-core group (CMDC) served as the control. Three experimental groups consisted of a stainless steel post/composite-resin (Charisma) core group (SCOM), zirconium dioxide post/composite-resin (Charisma) core group (ZCOM), and zirconium dioxide post/ceramic (Cosmopost) core group (ZCER). The post spaces were prepared, posts were seated, cores were formed, and 40 post-and-core foundations were cemented into the roots. Following thermal cycling (5000 cycles between 5 degrees C and 55 degrees C with a dwell time of 30 seconds), a compressive load was applied to the inclined surface of each specimen at a 130-degree angle to the specimen long axes in a universal testing machine at a crosshead speed of 1 mm/min until failure occurred. Force to failure (N) was recorded. Data were analyzed with a 1-way analysis of variance and Bonferroni tests to determine the difference between the groups (alpha=.05). For pairwise comparisons among group mean values, P < .0083 indicated statistical significance and established the overall confidence level at 95%.


RESULTS
Groups CMDC (738.6 N +/- 10.2) and ZCER (710.2 N +/- 5.3) exhibited the highest resistance to fracture. The ZCOM group showed the lowest fracture resistance (450.3 N +/- 5.7). The fracture resistance of the SCOM group (565 N +/- 7.2) was lower than the CMDC and ZCER groups, and higher than the ZCOM group. The differences among the groups were significant (P < .001) except for CMDC and ZCER (P < .016).


CONCLUSIONS
Within the limitations of this study, the cast metal post/core and zirconia post/ceramic core foundations were found to be more fracture resistant than the zirconia post/composite-resin core and stainless steel post/composite-resin core foundations. Aside from its desirable esthetic properties, the zirconia post/ceramic core combination demonstrated high resistance to fracture.
Dental Sciences Center, Gulhane Military Medical Academy, Ankara, Turkey.
Faruk Taner
FT
Dilmener
Cumhur
C
Sipahi
Mehmet
M
Dalkiz
D000704:Analysis of Variance; D003188:Composite Resins; D019245:Compressive Strength; D003722:Dental Alloys; D003776:Dental Porcelain; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D006801:Humans; D007180:Incisor; D008422:Materials Testing; D011176:Post and Core Technique; D013193:Stainless Steel; D015040:Zirconium
C084111:Charisma composite resin; D003188:Composite Resins; D003722:Dental Alloys; D003776:Dental Porcelain; D013193:Stainless Steel; D015040:Zirconium; C028541:zirconium oxide