In vitro mechanical analysis of complete-arch mandibular implant-supported fixed prostheses abutment screws after cyclic loading

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Abstract

Statement of problem Clinicians question when to evaluate for worn or loose implant-supported retainer screws to prevent possible clinical complications. Purpose The purpose of this study was to compare differences among initial and postdynamically loaded detorque values and identify physical structural changes of prosthetic retaining screws in a simulated implant-supported mandibular complete fixed prosthesis. Material and methods Nine groups and nonloaded controls comprising a 5-implant-supported, milled titanium framework were fabricated and assembled (screw torque 35 Ncm). Dynamic loading (20 to 220 N) was applied to simulate 2 years of oral function. After testing, screw detorque values were measured (ΔT, initial-detorque value). A scanning electron microscopic analysis of screw threads was used to assess physical changes. Data were analyzed by 2-way ANOVA to determine the influence of loading and implant position on ΔT (α=.05). Results ΔT values of loaded and nonloaded groups were compared separately at each implant position and showed a significant difference only for the implant in the central position (P=.002). All positions were compared in terms of ΔT values separately for loaded and nonloaded conditions. A significantly higher ΔT was found in 1 cantilever area of the loaded group, whereas a significantly lower ΔT value was found in the central position in the nonloaded group. No statistically significant differences were found in physical changes between loading and nonloading or among implant positions. Conclusions When delivering a multiimplant supported prosthesis, the application of dynamic loading and the sequence in which implant screws are tightened could influence the subsequent detorque value of a screw; they have no effect on the physical appearance of screws after extended function.

Original languageEnglish (US)
Pages (from-to)432-439
Number of pages8
JournalJournal of Prosthetic Dentistry
Volume113
Issue number5
DOIs
StatePublished - May 1 2015

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Prostheses and Implants
Torque
Titanium
Analysis of Variance
Electrons
Control Groups
In Vitro Techniques

ASJC Scopus subject areas

  • Oral Surgery

Cite this

@article{aadd8b4b0982456ba11c2268020d58dc,
title = "In vitro mechanical analysis of complete-arch mandibular implant-supported fixed prostheses abutment screws after cyclic loading",
abstract = "Statement of problem Clinicians question when to evaluate for worn or loose implant-supported retainer screws to prevent possible clinical complications. Purpose The purpose of this study was to compare differences among initial and postdynamically loaded detorque values and identify physical structural changes of prosthetic retaining screws in a simulated implant-supported mandibular complete fixed prosthesis. Material and methods Nine groups and nonloaded controls comprising a 5-implant-supported, milled titanium framework were fabricated and assembled (screw torque 35 Ncm). Dynamic loading (20 to 220 N) was applied to simulate 2 years of oral function. After testing, screw detorque values were measured (ΔT, initial-detorque value). A scanning electron microscopic analysis of screw threads was used to assess physical changes. Data were analyzed by 2-way ANOVA to determine the influence of loading and implant position on ΔT (α=.05). Results ΔT values of loaded and nonloaded groups were compared separately at each implant position and showed a significant difference only for the implant in the central position (P=.002). All positions were compared in terms of ΔT values separately for loaded and nonloaded conditions. A significantly higher ΔT was found in 1 cantilever area of the loaded group, whereas a significantly lower ΔT value was found in the central position in the nonloaded group. No statistically significant differences were found in physical changes between loading and nonloading or among implant positions. Conclusions When delivering a multiimplant supported prosthesis, the application of dynamic loading and the sequence in which implant screws are tightened could influence the subsequent detorque value of a screw; they have no effect on the physical appearance of screws after extended function.",
author = "Sananez, {Andreina Josefina} and Lefebvre, {Carol A} and Looney, {Stephen Warwick} and Baker, {Philip S} and Don Mettenburg and Frederick Rueggeberg",
year = "2015",
month = "5",
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doi = "10.1016/j.prosdent.2014.09.026",
language = "English (US)",
volume = "113",
pages = "432--439",
journal = "Journal of Prosthetic Dentistry",
issn = "0022-3913",
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TY - JOUR

T1 - In vitro mechanical analysis of complete-arch mandibular implant-supported fixed prostheses abutment screws after cyclic loading

AU - Sananez, Andreina Josefina

AU - Lefebvre, Carol A

AU - Looney, Stephen Warwick

AU - Baker, Philip S

AU - Mettenburg, Don

AU - Rueggeberg, Frederick

PY - 2015/5/1

Y1 - 2015/5/1

N2 - Statement of problem Clinicians question when to evaluate for worn or loose implant-supported retainer screws to prevent possible clinical complications. Purpose The purpose of this study was to compare differences among initial and postdynamically loaded detorque values and identify physical structural changes of prosthetic retaining screws in a simulated implant-supported mandibular complete fixed prosthesis. Material and methods Nine groups and nonloaded controls comprising a 5-implant-supported, milled titanium framework were fabricated and assembled (screw torque 35 Ncm). Dynamic loading (20 to 220 N) was applied to simulate 2 years of oral function. After testing, screw detorque values were measured (ΔT, initial-detorque value). A scanning electron microscopic analysis of screw threads was used to assess physical changes. Data were analyzed by 2-way ANOVA to determine the influence of loading and implant position on ΔT (α=.05). Results ΔT values of loaded and nonloaded groups were compared separately at each implant position and showed a significant difference only for the implant in the central position (P=.002). All positions were compared in terms of ΔT values separately for loaded and nonloaded conditions. A significantly higher ΔT was found in 1 cantilever area of the loaded group, whereas a significantly lower ΔT value was found in the central position in the nonloaded group. No statistically significant differences were found in physical changes between loading and nonloading or among implant positions. Conclusions When delivering a multiimplant supported prosthesis, the application of dynamic loading and the sequence in which implant screws are tightened could influence the subsequent detorque value of a screw; they have no effect on the physical appearance of screws after extended function.

AB - Statement of problem Clinicians question when to evaluate for worn or loose implant-supported retainer screws to prevent possible clinical complications. Purpose The purpose of this study was to compare differences among initial and postdynamically loaded detorque values and identify physical structural changes of prosthetic retaining screws in a simulated implant-supported mandibular complete fixed prosthesis. Material and methods Nine groups and nonloaded controls comprising a 5-implant-supported, milled titanium framework were fabricated and assembled (screw torque 35 Ncm). Dynamic loading (20 to 220 N) was applied to simulate 2 years of oral function. After testing, screw detorque values were measured (ΔT, initial-detorque value). A scanning electron microscopic analysis of screw threads was used to assess physical changes. Data were analyzed by 2-way ANOVA to determine the influence of loading and implant position on ΔT (α=.05). Results ΔT values of loaded and nonloaded groups were compared separately at each implant position and showed a significant difference only for the implant in the central position (P=.002). All positions were compared in terms of ΔT values separately for loaded and nonloaded conditions. A significantly higher ΔT was found in 1 cantilever area of the loaded group, whereas a significantly lower ΔT value was found in the central position in the nonloaded group. No statistically significant differences were found in physical changes between loading and nonloading or among implant positions. Conclusions When delivering a multiimplant supported prosthesis, the application of dynamic loading and the sequence in which implant screws are tightened could influence the subsequent detorque value of a screw; they have no effect on the physical appearance of screws after extended function.

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