The Clinical Evaluations of a 3mm Extended Hex on a Titanium Screw Type Implant
Weiner, Saul; Aboyoussef, Hoda; Zweig, Barry; Thompson, Van: University of Medicine & Dentistry of New Jersey, 110 Bergen Street, University Heights, Newark, NJ, 07103, USA Kwan, Norman; Yang, Silvia: Canadian Dental Implant Institute, 206 King Street, St. Catharines, ON, L2R 3J7, Canada

Most dental implant systems today employ either an external or internal hexed implant which connects to an abutment using a screw for stabilization of a prosthesis. This report reviews the success of a one-piece implant system with a 3mm extended hex to which the prosthesis can be directly attached, either with a screw or by cement.
In one series, a total of 172 consecutive patients with more than 800 implants were evaluated with one group receiving the two-piece device in a two-stage procedure while the second group received a two-piece device in a one-stage procedure. Eight year Kaplan-Meier life table analysis indicated no significant difference in survival between the two-stage (91.6%) and the one-stage (89.7) protocols, p<0.05.
In another one-year prospective clinical study, 140 (88.61%) of the one-piece non-submergible, implantable devices achieved osseointegration and were able to support a total of 64 fixed restorations. 20 out of 32 single implant restorations were screw-retained crowns the other 12 single crowns were cemented. 32 other restorations were supported by multiple implants and all were screw retained. No prosthetic complication was observed in this one-year period.
This 3mm extension provides stable support in lateral function and retention of the final prosthesis - no separate abutment was used. The abutment-implant component gap is replaced by a smooth-rough interface. The removal of the component gap eliminates all prosthetic complications. In addition, the location of the smooth-rough (abutment-implant) interface minimizes horizontal and vertical bone loss around implant support of the prosthesis.
Use of this one-piece system eliminates problems associated with impression transfer of the two-stage external hex and the uncertainties in selection and use of abutments. In addition, the lack of an abutment-implant component gap reduces prosthetic instability, reduces the possibilities of loss of crestal bone adjacent to the abutment-implant interface and the possibility of component fracture.

1. Bernard JP, Belser UC, Martinet JP, Borgis SA.: Osseointegration of Branemark Fixtures Using a Single-step Operating Technique. A Preliminary Prospective One-year Study in the Edentulous Mandible. Clin Oral Implants Res 1995;6:122-129.
2. Hermann JS, Cochran DL, Nummikoski PV, Buser D: Crestal Bone Changes Around Titanium Implants. A Radiographic Evaluation of Unloaded Nonsubmerged and Submerged Implants in the Canine Mandible. J Periodontol 1997;68:1117-1130.

This research is supported by Biomedical Implant Technology Inc.