The Effect of Tissue Entrapment on Screw Loosening at the Implant/Abutment Interface of External- and Internal-Connection Implants: An In Vitro Study

Helios A. Zeno, Renan L. Buitrago, Sidney S. Sternberger, Marisa E. Patt, Nick Tovar, Paulo Coelho, Kenneth S. Kurtz, Frank J. Tuminelli

Research output: Contribution to journalArticle

Abstract

Purpose: To compare the removal of torque values of machined implant abutment connections (internal and external) with and without soft tissue entrapment using an in vitro model. Materials and Methods: Thirty external- and 30 internal-connection implants were embedded in urethane dimethacrylate. Porcine tissue was prepared and measured to thicknesses of 0.5 and 1.0 mm. Six groups (n = 10) were studied: External- and internal-connection implants with no tissue (control), 0.5, and 1.0 mm of tissue were entrapped at the implant/abutment interface. Abutments were inserted to 20 Ncm for all six groups. Insertion torque values were recorded using a digital torque gauge. All groups were then immersed in 1 M NaOH for 48 hours to dissolve tissue. Subsequent reverse torque measurements were recorded. Mean and standard deviation were determined for each group, and one-way ANOVA and Bonferroni test were used for statistical analysis. Results: All 60 specimens achieved a 20-Ncm insertion torque, despite tissue entrapment. Reverse torque measurements for external connection displayed a statistically significant difference (p < 0.05) between all groups with mean reverse torque values for the control (13.71 ± 1.4 Ncm), 0.5 mm (7.83 ± 2.4 Ncm), and 1.0 mm tissue entrapment (2.29 ± 1.4 Ncm) groups. Some statistically significant differences (p < 0.05) were found between internal-connection groups. In all specimens, tissue did not completely dissolve after 48 hours. Conclusions: External-connection implants were significantly affected by tissue entrapment; the thicker the tissue, the lower the reverse torque values noted. Internal-connection implants were less affected by tissue entrapment.

Original languageEnglish (US)
Pages (from-to)216-223
Number of pages8
JournalJournal of Prosthodontics
Volume25
Issue number3
DOIs
StatePublished - Apr 1 2016

Keywords

  • Gingival entrapment
  • Preload
  • Screw loosening
  • Tissue entrapment

ASJC Scopus subject areas

  • Dentistry(all)

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