Effect of fluid contamination on reverse torque values in implant-abutment connections under oral conditions

Mechanical stability of implant-abutment set is fundamentally important for the success in implant supported rehabilitation. For this, the knowledge about torque removal values is essential. In this way, the objective of this work was to evaluate the torque reverse values in indexed abutments of Morse Taper system. Five Morse taper implants with their respective abutments were tested (n=5). Each abutment received a sequence of two consecutive torques in insertion (15Ncm) with an interval of ten minutes, and one reverse torque, all measured by digital torque wrench. The t-student test with 5% significance was used to evaluate the data. The analysis of results showed there is statistical significant difference in reverse torque values between the insertion torque value and reverse torque value intra-group, the indexed abutments presented an average percentage of torque loosing of 15% (P=0.002). It is possible to conclude that the use of indexed abutments of Morse taper system presented statistical significant reduction of reverse torque values, which in turns increase the risk of no biomechanical instability.

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A Novel Technique Using Polytetrafluoroethylene Tape to Solve Screw Loosening Complication in Implant-Supported Single Crowns

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18010125 ◽

2020 ◽

Vol 18 (1) ◽

pp. 125

Author(s):

Luis F. Félix ◽

Michell Medina ◽

Cristina Gómez-Polo ◽

Rubén Agustín-Panadero ◽

Rocío Ortega ◽

...

Keyword(s):

Control Group ◽

Screw Loosening ◽

Novel Technique ◽

Reverse Torque ◽

Titanium Screws ◽

Implant Abutment ◽

Torque Values ◽

Single Crowns ◽

Screw Group ◽

Abutment Screw

This study aimed to analyze a novel technique to make screws with greater untightening resistance and to solve screw loosening in implant-supported single crowns. Thirty grade IV titanium straight abutments were screwed onto 30 external hex implants using grade IV titanium screws (30 Ncm). They were exposed to cyclic loading (300,000 cycles, 200 N). Samples were divided into 4 groups (15 samples per group): new screws (SCREW group) (control), reused screws (rSCREW group), new screws wrapped with polytetrafluoroethylene (PTFE) tape (PTFE group), and reused screws wrapped with PTFE tape (rPTFE group). Reverse torque values (RTVs) were recorded with a digitally calibrated implant motor. Mean RTVs observed were 14.46 N (±1.10 N) for the control group, 14.42 N (±1.22 N) for the rSCREW group, 19.97 N (±1.16 N) for the PTFE group, and 19.13 N (±2.38 N) for the rPTFE group. Statistically significant differences were found between RTVs of both groups employing screws without PTFE tape (SCREW and rSCREW groups) compared with those using screws wrapped with PTFE tape (PTFE and rPTFE) (p < 0.001). These results suggest that wrapping the implant–abutment screw with PTFE tape may effectively lower the risk of loosening and even constitute a solution when this complication occurs in implant single crowns.

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Reverse torque values of abutment screws after dynamic loading: The effects of sealant agents and the taper of conical connections

Journal of Oral Implantology ◽

10.1563/aaid-joi-d-19-00228 ◽

2020 ◽

Author(s):

Arda Ozdiler ◽

suleyman dayan ◽

Burc Gencel ◽

Gulbahar Isık-Ozkol

Keyword(s):

Dynamic Loading ◽

Antibacterial Agent ◽

In Vitro Study ◽

Control Group ◽

Silicone Sealant ◽

Reverse Torque ◽

The Stability ◽

Torque Values ◽

Chlorhexidine Gel

This in vitro study evaluated the influence of taper angles on the internal conical connections of implant systems and of the application of chlorhexidine gel as an antibacterial agent or a polyvinyl siloxane (PVS) sealant on the reverse torque values of abutment screws after dynamic loading. The current study tested four implant systems with different taper angles (5.4°, 12°, 45°, and 60°). Specimens were divided into three groups: control (neither chlorhexidine gel filled nor silicone sealed), 2% chlorhexidine gel-filled or silicone-sealed group, and group subjected to a dynamic load of 50 N at 1 Hz for 500,000 cycles prior to reverse torque measurements. Quantitative positive correlation was observed between the taper angle degree and the percentage of tightening torque loss. However, this correlation was significant only for the 60° connection groups except in the group in which a sealant was applied ( p = 0.013 for the control group, p = 0.007 for the chlorhexidine group). Percentages of decrease in the torque values of the specimens with silicone sealant application were significantly higher compared with both the control and chlorhexidine groups ( p = 0.001, p = 0.002, p = 0.001, and p = 0.002, respectively, according to the increasing taper angles); the percentage of decrease in torque values due to chlorhexidine application was statistically insignificant when compared with the control group. The application of gel-form chlorhexidine as an antibacterial agent does not significantly affect the stability of the implant–abutment connection under dynamic loads. PVS sealants may cause screw loosening under functional loads.

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Evaluation of reverse torque values and failure loads of three different abutment designs with internal connections

Dental Research Journal ◽

10.4103/1735-3327.302891 ◽

2020 ◽

Vol 17 (6) ◽

pp. 439

Author(s):

AzamSadat Mostafavi ◽

Saied Nokar ◽

Habib Hajimiragha ◽

Leyla Sadighpour

Keyword(s):

Reverse Torque ◽

Failure Loads ◽

Torque Values ◽

Internal Connections

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Axial Displacements and Removal Torque Changes of Five Different Implant-Abutment Connections under Static Vertical Loading

Materials ◽

10.3390/ma13030699 ◽

2020 ◽

Vol 13 (3) ◽

pp. 699 ◽

Cited By ~ 2

Author(s):

Ki-Seong Kim ◽

Young-Jun Lim

Keyword(s):

Static Loading ◽

Testing Machine ◽

Butt Joint ◽

Removal Torque ◽

Vertical Loading ◽

Implant Abutment ◽

Before And After ◽

Masticatory Force ◽

Torque Values ◽

Molar Region

The aim of this study was to examine the settling of abutments into implants and the removal torque value under static loading. Five different implant-abutment connections were selected (Ext: external butt joint + two-piece abutment; Int-H2: internal hexagon + two-piece abutment; Int-H1: internal hexagon + one-piece abutment; Int-O2: internal octagon + two-piece abutment; Int-O1: internal octagon + one-piece abutment). Ten implant-abutment assemblies were loaded vertically downward with a 700 N load cell at a displacement rate of 1 mm/min in a universal testing machine. The settling of the abutment was obtained from the change in the total length of the entire implant-abutment unit before and after loading using an electronic digital micrometer. The post-loading removal torque value was compared to the initial torque value with a digital torque gauge. The settling values and removal torque values after 700 N static loading were in the following order, respectively: Ext < Int-H1, Int-H2 < Int-O2 < Int-O1 and Int-O2 < Int-H2 < Ext < Int-H1, Int-O1 (α = 0.05). After 700 N vertical static loading, the removal torque values were statistically different from the initial values, and the post-loading values increased in the Int-O1 group and Int-H1 group (α = 0.05) and decreased in the Ext group, Int-H2 group, and Int-O2 group (α = 0.05). On the basis of the results of this study, it should be taken into consideration that a loss of the preload due to the settling effect can lead to screw loosening during a clinical procedure in the molar region where masticatory force is relatively greater.

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In Vitro Evaluation of Manual Torque Values Applied to Implant-Abutment Complex by Different Clinicians and Abutment Screw Loosening

BioMed Research International ◽

10.1155/2017/7376261 ◽

2017 ◽

Vol 2017 ◽

pp. 1-9 ◽

Cited By ~ 5

Author(s):

Onur Dincer Kose ◽

Burcin Karataslı ◽

Sabit Demircan ◽

Taha Emre Kose ◽

Erhan Cene ◽

...

Keyword(s):

Dynamic Loading ◽

Optical Microscope ◽

Control Group ◽

Screw Loosening ◽

Loading Test ◽

Torque Wrench ◽

Implant Abutment ◽

Torque Values ◽

Abutment Screw

Preload is applied to screws manually or using a torque wrench in dental implant systems, and the preload applied must be appropriate for the purpose. The aim of this study was to assess screw loosening and bending/torsional moments applied by clinicians of various specialties following application of manual tightening torque to combinations of implants and abutments. Ten-millimeter implants of 3.7 and 4.1 mm diameters and standard or solid abutments were used. Each group contained five implant-abutment combinations. The control and experimental groups comprised 20 and 160 specimens, respectively. Implants in the experimental group were tightened by dentists of different specialties. Torsional and bending moments during tightening were measured using a strain gauge. Control group and implants with preload values close to the ideal preload were subjected to a dynamic loading test at 150 N, 15 Hz, and 85,000 cycles. The implants that deformed in this test were examined using an optical microscope to assess deformities. Manual tightening did not yield the manufacturer-recommended preload values. Dynamic loading testing suggested early screw loosening/fracture in samples with insufficient preload.

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An Indirect Method to Measure Abutment Screw Preload: A Pilot Study Based on Micro-CT Scanning

Brazilian Dental Journal ◽

10.1590/0103-6440201300274 ◽

2015 ◽

Vol 26 (6) ◽

pp. 596-601 ◽

Cited By ~ 1

Author(s):

Carlos Eduardo E. Rezende ◽

Jason Alan Griggs ◽

Yuanyuan Duan ◽

Amanda M. Mushashe ◽

Gisele Maria Correr Nolasco ◽

...

Keyword(s):

Ct Scanning ◽

Measuring Method ◽

Micro Ct ◽

Ct Scanner ◽

Removal Torque ◽

Ct Technique ◽

Original Length ◽

Implant Abutment ◽

Torque Values ◽

Abutment Screw

This study aimed to measure the preload in different implant platform geometries based on micro-CT images. External hexagon (EH) implants and Morse Tapered (MT) implants (n=5) were used for the preload measurement. The abutment screws were scanned in micro-CT to obtain their virtual models, which were used to record their initial length. The abutments were screwed on the implant with a 20 Ncm torque and the set composed by implant, abutment screw and abutment were taken to the micro-CT scanner to obtain virtual slices of the specimens. These slices allowed the measurement of screw lengths after torque application and based on the screw elongation. Preload values were calculated using the Hooke's Law. The preloads of both groups were compared by independent t-test. Removal torque of each specimen was recorded. To evaluate the accuracy of the micro-CT technique, three rods with known lengths were scanned and the length of their virtual model was measured and compared with the original length. One rod was scanned four times to evaluate the measuring method variation. There was no difference between groups for preload (EH = 461.6 N and MT = 477.4 N), but the EH group showed higher removal torque values (13.8±4.7 against 8.2±3.6 Ncm for MT group). The micro-CT technique showed a variability of 0.053% and repeatability showed an error of 0.23 to 0.28%. Within the limitations of this study, there was no difference between external hexagon and Morse taper for preload. The method using micro-CT may be considered for preload calculation.

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