[Evaluation of survival rate, bone loss and post operative complication in fixed retained prosthesis with all-on-4 technique: review article]

The purpose of this study was to evaluate the survival rate, mean bone loss and post operative complication of implants inserted in All-on-4 technique. The literature was searched using keywords angled implant, All-on-4, tilted implant and graftless technique in the last 10 years [2001 to 2011] and clinical trial article that evaluated survival rate and mean bone loss around axial and tilted implants in All-on-4 technique was selected and evaluated. A total of 73 articles were found by searching. After evaluation of titles and abstracts, finally 10 clinical trial, that were fully consistent with including criteria such as mean of bone loss and survival rate was selected and evaluated. Results showed that the survival rate [96-100%] and mean bone loss [0.34-1.9 mm] with All-on-4 technique in immediate loading is comparable with other implant support treatment plan. Comparison of implant survival and bone loss in axial and tilted implant in All-on-4 system showed that this treatment plan has consistent result with other conventional implant support prosthesis. Also, postoperative complication including fractures of the acrylic temporary prosthesis, detachment of the teeth, abutment or prosthesis screw loosening have been reported with All-on-4 technique.

Evaluation of torque loss value of MAD/MAM zirconia abutments with prefabricated titanium abutments

In response to esthetic demand of patients, ceramic abutments have been developed. Despite esthetic of zirconia abutments, machining accuracy of these abutments has always been a question. Any misfit in the abutment-implant interface connection can lead to detorque and screw loosening. The aim of this study was to compare torque loss value of manually aided design/manually aided manufacture [MAD/MAM] zirconia abutments with prefabricated titanium abutments. Seven titanium abutments [Branemark RP, Easy abutment] and seven copy milled abutments which were duplicated from the prefabricated Zirkonzhan [ZirkonZahn, Sand in Taufers, Italy] were prepared. After sintering process of zirconia abutment, all abutments were fastened with a torque screw under 35 Ncm. Detorque measurements were performed per group pushing the reverse button of the Torque controller soon after screw tightening with values registered. The mean torque loss were calculated and compared using Student's t test. The mean of torque loss was 12.71 Ncm with standard deviation of 1.70 for prefabricated titanium abutments and 15.50 Ncm with standard deviation of 4.67 for MAD-MAM abutments. The difference between the two groups was not statistically significant [P=0.23]. Within the limitation of this study, MAD-MAM ceramic abutments could maintain the applied torque comparing to the prefabricated abutments