Effect of mechanical loading on the removal torque of different types of tapered connection abutments for dental implants.
BACKGROUND
The mechanical behavior of internal taper implant abutment designs needs to be evaluated.


OBJECTIVE
The purpose of this study was to evaluate the effect of simulated mechanical loading on the removal torque of 1-piece and 2-piece abutments connected to internal taper oral implants.


METHODS
Forty-eight internally notched taper implants were divided into 2 groups of 24. Group OP received solid (1-piece) abutments; group TP received esthetic (2-piece) abutments. Each group was further subdivided into subgroups C (control) without mechanical loading and T (test) with mechanical loading. In groups OPC and TPC, the abutments were placed and removed and the removal torque values (RTVs) registered. In groups OPT and TPT, abutments were placed, mechanically loaded (500 000 cycles), removed, and the RTVs registered. Groups TPC and TPT were further tested for the traction force necessary to dislodge the abutment from the implant. For data analysis, the Student t test (for RTVs) and the Mann-Whitney U test (for TFVs) (α=.05) were performed.


RESULTS
All abutments tested presented torque loss with RTVs lower than the placement torque. A statistically significant difference (P=.002) was found between groups OPC (81.6% of placement torque) and OPT mean RTVs results (85.0% of placement torque), while no statistical differences (P=.362) were found between groups TPC (63.7% of placement torque) and TPT (59.1% of placement torque). The traction force values necessary to dislodge the abutment from the implant, however, were significantly higher (P<.001) for group TPT than for group TPC.


CONCLUSIONS
Cold welding did not occur in any of the abutment specimens tested. Even after the mechanical loading, esthetic abutments presented similar RTVs. The traction force necessary to remove esthetic abutments from inside the implants presented a 2-fold increase after mechanical loading.
Lecturer, School of Dentistry, State University of Maringá-UEM, Maringá, Brazil.
Marilene
M
Pintinha
Edevaldo Tadeu
ET
Camarini
Sergio
S
Sábio
Jefferson Ricardo
JR
Pereira
D059605:Dental Implant-Abutment Design; D015921:Dental Implants; D003764:Dental Materials / Q000737:chemistry; D017267:Dental Prosthesis Design; D003799:Dental Stress Analysis / Q000295:instrumentation; D006801:Humans; D008422:Materials Testing; D013314:Stress, Mechanical; D013499:Surface Properties; D014025:Titanium / Q000737:chemistry; D019415:Torque
D015921:Dental Implants; D003764:Dental Materials; D014025:Titanium