Mechanical testing of indirect composite materials directly applied on implant abutments.
OBJECTIVE
To test the strength to failure and fracture mode of three indirect composite materials directly applied onto Ti-6Al-4V implant abutments vs cemented standard porcelain-fused-to-metal (PFM) crowns.


METHODS
Sixty-four locking taper abutments were randomly allocated to four groups and were cleaned in ethanol in an ultrasonic bath for 5 min. After drying under ambient conditions, the abutments were grit blasted and a custom 4-cusp molar crown mold was utilized to produce identical crowns (n = 16 per group) of Tescera (Bisco), Ceramage (Shofu), and Diamond Crown (DRM) according to the manufacturer's instructions. The porcelain-fused-to-metal crowns were fabricated by conventional means involving the construction and a wax pattern and casting of a metallic coping followed by sintering of increasing layers of porcelain. All crowns were loaded to failure by an indenter placed at one of the cusp tips at a 1 mm/min rate. Subsequently, fracture analysis was performed by means of stereomicroscopy and scanning electron microscopy. One-way ANOVA at 95% level of significance was utilized for statistical analysis.


RESULTS
The single load to failure (± SD) results were: Tescera (1130 ± 239 N), Ceramage (1099 ± 257 N), Diamond Crown (1155 ± 284 N), and PFM (1081 ± 243 N). Stereomicroscopy analysis showed two distinct failure modes, where the loaded cusp failed either with or without abutment/metallic coping exposure. SEM analysis of the fractures showed multiple crack propagation towards the cervical region of the crown below a region of plastic deformation at the indenter contact region.


CONCLUSIONS
The three indirect composites and PFM systems fractured at loads higher than those typically associated with normal occlusal function. Although each material had a different composition and handling technique, no significant differences were found concerning their single load to fracture resistance among composite systems and PFM.
Andriani
Wilson
W
Department of Prosthodontics, Universidade Federal de Santa Catarina, Florianopolis, Brazil.
Suzuki
Marcelo
M
Bonfante
Estevam A
EA
Carvalho
Ricardo M
RM
Silva
Nelson R
NR
Coelho
Paulo G
PG
D000497:Alloys; D003188:Composite Resins / Q000737:chemistry; D019245:Compressive Strength; D003442:Crowns; D000044:Dental Abutments; D003722:Dental Alloys; D015921:Dental Implants; D017267:Dental Prosthesis Design; D017268:Dental Prosthesis Retention / Q000379:methods; D019094:Dental Prosthesis, Implant-Supported; D019232:Dental Restoration Failure; D003799:Dental Stress Analysis; D008422:Materials Testing; D016876:Metal Ceramic Alloys; D008855:Microscopy, Electron, Scanning; D011897:Random Allocation; D014025:Titanium
D000497:Alloys; D003188:Composite Resins; D003722:Dental Alloys; D015921:Dental Implants; D016876:Metal Ceramic Alloys; C031462:titanium alloy (TiAl6V4); D014025:Titanium