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Observational Study
. 2025 Apr 17;11(1):32.
doi: 10.1186/s40729-025-00620-y.

Retention forces in mini-dental-implant retained mandibular overdentures: 10-year outcomes of a non-comparative longitudinal observational study

Hristina Bukvic #  1 , Nicole Schenk #  1 , Sebastian Hinz  1 , Martin Schimmel  1   2 , Norbert Enkling #  1   3 , Samir Abou-Ayash #  4   5
Affiliations
Observational Study

Retention forces in mini-dental-implant retained mandibular overdentures: 10-year outcomes of a non-comparative longitudinal observational study

Hristina Bukvic et al. Int J Implant Dent. .

Abstract

Purpose: To report the evaluation of in vivo retention forces after replacement of O-rings in one-piece mini dental implants (MDIs), retaining mandibular implant overdentures (IODs) with ball/O-ring attachments during 10 years assessed.

Methods: Twenty patients received new complete dentures, which were converted into IODs through stabilization with four MDIs (Condent GmbH; diameter: 1.8 mm) placed in the interforaminal region. Retention forces were measured at the male and female parts at baseline, 5, and 10 years using a validated strain gauge. Fourteen patients completed the 10-year follow-up.

Results: After 10 years, a minor but significant reduction in retention force was observed in the male part of the implant at position 44. In contrast, neither the male part at the other implant positions nor the female part at any position showed a significant decrease in retention force compared to baseline. After replacement of the O-ring inserts, baseline values could be restored and no significant changes in retention forces were observed at the 10-year follow-up. No difference in anterior and posterior implants could be determined.

Conclusions: Initial retention forces of mandibular IODs supported by four MDIs can be reestablished by replacing the O-rings with pristine ones after 10 years, with stable retention forces at both the male and female parts throughout the functional period, with no discernible differences between anterior and posterior implants.

Keywords: Denture retention; Elderly patients; Mini dental implants; Narrow-diameter implants; Overdenture; Retention forces.

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Conflict of interest statement

Declarations. Ethics approval and consent to participate: Informed consent was obtained from all subjects involved in the study. Consent for publication: Not applicable. Competing interests: The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
Schematic drawing of a study implant with a MH2 matrix and the corresponding nitrile rubber O-ring, reprinted from Ref. [26]
Fig. 2
Fig. 2
Schematic illustration of the timing of the O-ring replacement
Fig. 3
Fig. 3
The measurement of the retention forces at the 10-year follow-up. a Auxiliary reconstructions for measurement of retention forces: MH2 matrix with pristine O-ring attachment and a pristine ball attachment, and b measurement of the retention force when dis-connecting the pristine ball attachment from the female parts of the prosthesis
See this image and copyright information in PMC

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