An in vitro analysis of implant screw torque loss with external hex and internal connection implant systems

Document Type

Article

Publication Date

12-1-2006

Abstract

PURPOSE: The purpose of this study was to examine, in a controlled environment, effects of connection design upon screw stability. Implant fixtures have 2 types of connections to the abutment: internal connection and external hex. Four implant systems were tested: Bio-Lok (external hex; Bio-Lok International, Inc., Deerfield Beach, FL); Zimmer (internal connection; Zimmer Dental, Carlsbad, CA); Nobel Biocare (external hex; Nobel Biocare USA, Inc., Yorba Linda, CA); and Astra Tech (internal connection; Astra Tech Inc., Waltham, MA). MATERIALS AND METHODS: Ten samples of each system, including base, implant, abutment, and molar crown, were loaded to 200 N for 1 × 10 cycles. Screws were tightened to manufacturers' recommendations,and torque audits done at 2.5 × 10, 5 × 10, 7.5 × 10, and 1 × 10 cycles. RESULTS: The Bio-Lok samples lost an average of 10% of the original torque values, the Astra Tech group lost almost all of the torque and loosened, while the Zimmer and Nobel Biocare samples lost an average of 50% of the torque but did not loosen (P ≤ 0.05). CONCLUSIONS: It may be concluded from this study that although internal connections are clinically favored, this study did not show any advantage relative to screw loosening. However, screw design may be a significant factor in loosening of the joint. © 2006 Lippincott Williams & Wilkins, Inc.

Identifier

33845746236 (Scopus)

Publication Title

Implant Dentistry

External Full Text Location

https://doi.org/10.1097/01.id.0000245440.09464.48

ISSN

10566163

PubMed ID

17172962

First Page

427

Last Page

435

Issue

4

Volume

15

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