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. 2015 Jul-Aug;12(4):359-64.
doi: 10.4103/1735-3327.161458.

Effect of tightening torque on the marginal adaptation of cement-retained implant-supported fixed dental prostheses

Jalil Ghanbarzadeh  1 , Hossin Dashti  1 , Reza Karamad  1 , Marzieh Alikhasi  2 , Mohammadreza Nakhaei  1
Affiliations

Effect of tightening torque on the marginal adaptation of cement-retained implant-supported fixed dental prostheses

Jalil Ghanbarzadeh et al. Dent Res J (Isfahan). 2015 Jul-Aug.

Abstract

Background: The final position of the abutment changes with the amount of tightening torque. This could eventually lead to loss of passivity and marginal misfit of prostheses. The aim of this study was to evaluate the effect of three different tightening torques on the marginal adaptation of 3-unit cement-retained implant-supported fixed dental prostheses (FDPs).

Materials and methods: Two implants (Straumann) were inserted in an acrylic block so that one of the implants was placed vertically and the other at a 15° vertical angle. A straight abutment and a 15° angulated abutment were connected to the vertically and obliquely installed implants, respectively, so that the two abutments were parallel. Then, 10 cement-retained FDPs were waxed and cast. Abutments were tightened with 10, 20, and 35 Ncm torques, respectively. Following each tightening torque, FDPs were luted on respective abutments with temporary cement. The marginal adaptation of the retainers was evaluated using stereomicroscope. FDPs were then removed from the abutments and were sectioned at the connector sites. The retainers were luted again on their respective abutments. Luting procedures and marginal adaptation measurement were repeated. Data were analyzed by ANOVA and least significant difference tests (α = 0.05). After cutting the FDP connectors, the independent samples t-test was used to compare misfit values (α = 0.05).

Results: Following 10, 20, and 35 Ncm tightening torques, the marginal discrepancy of the retainers of FDPs significantly increased (P < 0.05). There was no significant difference between the marginal discrepancies of these two retainers (P > 0.05). The marginal gap values of angulated abutment retainers (ANRs) were significantly higher than those of the straight abutment after cutting the connectors (P = 0.026).

Conclusion: Within the limitations of this study, the marginal misfit of cement-retained FDPs increased continuously when the tightening torque increased. After cutting the connectors, the marginal misfit of the ANRs was higher than those of the straight abutment retainers.

Keywords: Dental implants; fixed partial denture; implant-supported prosthesis; marginal adaptation; torque.

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Conflict of interest statement

Conflicts of Interest: The authors of this manuscript declare that they have no conflicts of interest, real or perceived, financial or nonfinancial in this article.

Figures

Figure 1
Figure 1
(a) Straight and angulated abutments were connected to their respective implants (b) wax pattern of cement-retained 3-unit fixed dental prosthese.
Figure 2
Figure 2
Vertical marginal discrepancy of the buccal side of one of the angulated abutment retainers following 20 (a) and 35 Ncm (b) torque tightening (×250).
See this image and copyright information in PMC

References

    1. Schwarz MS. Mechanical complications of dental implants. Clin Oral Implants Res. 2000;11(Suppl 1):156–8. - PubMed
    1. Binon PP. Implants and components: Entering the new millennium. Int J Oral Maxillofac Implants. 2000;15:76–94. - PubMed
    1. Scacchi M, Merz BR, Schär AR. The development of the ITI Dental implant system. Part 2: 1998-2000: Steps into the next millennium. Clin Oral Implants Res. 2000;11(Suppl 1):22–32. - PubMed
    1. Merz BR, Hunenbart S, Belser UC. Mechanics of the implant-abutment connection: An 8-degree taper compared to a butt joint connection. Int J Oral Maxillofac Implants. 2000;15:519–26. - PubMed
    1. Norton MR. An in vitro evaluation of the strength of an internal conical interface compared to a butt joint interface in implant design. Clin Oral Implants Res. 1997;8:290–8. - PubMed