Does Abutment Collar Length Affect Abutment Screw Loosening After Cyclic Loading?

2015 ◽  
Vol 41 (S1) ◽  
pp. 346-351 ◽  
Author(s):  
Hakimeh Siadat ◽  
Salma Pirmoazen ◽  
Elaheh Beyabanaki ◽  
Marzieh Alikhasi
Keyword(s):  
Cyclic Loading ◽  
Paired Comparison ◽  
Acrylic Resin ◽  
Screw Loosening ◽  
Ridge Augmentation ◽  
Torque Wrench ◽  
Before And After ◽  
Torque Loss ◽  
One Way Anova ◽  
Abutment Screw

A significant vertical space that is corrected with vertical ridge augmentation may necessitate selection of longer abutments, which would lead to an increased vertical cantilever. This study investigated the influence of different abutment collar heights on single-unit dental implant screw-loosening after cyclic loading. Fifteen implant-abutment assemblies each consisted of an internal hexagonal implant were randomly assigned to 3 groups: Group1, consisting of 5 abutments with 1.5 mm gingival height (GH); Group2, 5 abutments with 3.5 mm GH; and Group3, 5 abutments with 5.5 mm GH. Each specimen was mounted in transparent auto-polymerizing acrylic resin block, and the abutment screw was tightened to 35 Ncm with an electric torque wrench. After 5 minutes, initial torque loss (ITL) was recorded for all specimens. Metal crowns were fabricated with 45° occlusal surface and were placed on the abutments. A cyclic load of 75 N and frequency of 1 Hz were applied perpendicular to the long axis of each specimen. After 500 000 cycles, secondary torque loss (STL) was recorded. One-way ANOVA analysis was used to evaluate the effects of abutment collar height before and after cyclic loading. One-way ANOVA showed that ITL among the groups was not significantly different (P = .52), while STL was significantly different among the groups (P = .008). Post-hoc Tukey HSD tests showed that STL values were significantly different between the abutments with 1.5 mm GH (Group1) and with 5.5 mm GH (Group3) (P = .007). A paired comparison t-test showed that cyclic loading significantly influenced the STL in comparison with the ITL in each group. Within the limitations of this study, it can be concluded that increase in height of the abutment collar could adversely affect the torque loss of the abutment screw.

scholarly journals Effect of lateral oblique cyclic loading on microleakage and screw loosening of implants with different connections

2018 ◽  
Vol 12 (3) ◽  
pp. 183-189 ◽  
Author(s):  
Hakimeh Siadat ◽  
Hossain Najafi ◽  
Marzieh Alikhasi ◽  
Babak Falahi ◽  
Elaheh Beyabanaki ◽  
...  
Keyword(s):  
Cyclic Loading ◽  
Screw Loosening ◽  
Torque Wrench ◽  
Before And After ◽  
Torque Loss ◽  
Connection Type ◽  
Loading Methods ◽  
External Connection ◽  
Two Phases ◽  
Implant System

Background. The implant connection type might affect microleakage and screw loosening in two-piece implants. The aim of this study was to measure microleakage and screw loosening of two connections of Noble Biocare implant system before and after cyclic loading. Methods. Twelve samples were categorized into two groups: external hexagon (Branemark) and internal hexagon connection (Noble Active) and two implants as controls. The abutments were tightened to a 35 Ncm torque. Initial torque loss (ITL) was measured five minutes after retightening the abutment, using a digital torque wrench. The samples were covered with putty material to the abutment‒implant junction. Customized metal crowns with 45° inclinations were placed on the abutments and cyclic loading was performed accordingly. Thereafter, the secondary torque loss (STL) was measured. Microleakage test was also performed. Data were analyzed with Mann-Whitney and Wilcoxon tests (α=0.05). Results. There were no statistically significant differences between the two phases of gamma counting between and within two groups (P>0.05). However, STL after cyclic loading was less than ITL in both groups (P=0.042). Conclusion. Connection type and cyclic loading had no significant effect on microleakage. Furthermore, the internal connection had less TL as compared to the external connection. In addition, the STLs were less than ITLs in both groups.

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

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
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.

The effect of serrating abutment-implant mating surface on torque stability of implant-abutment connection, before and after cyclic loading.

2020 ◽  
Author(s):  
Vida Rezayani ◽  
Marzieh Alikhasi ◽  
Abbas Monzavi
Keyword(s):  
Cyclic Loading ◽  
Repeated Measures ◽  
Peak Load ◽  
T Test ◽  
The Other ◽  
Repeated Measures Anova ◽  
Implant Abutment ◽  
Before And After ◽  
Torque Loss ◽  
Connection Design

This study evaluated the effect of adding serration to the abutment-implant connection on torque maintenance before and after loading. Two implant systems with the same dimensions and connection design (internal 8˚morse taper octagon) were selected: one with non-serrated abutments (Simple line II) and the other one with serrated abutments (F & B). The removal torque value (RTV) was measured in two groups for each system: one group with one-piece abutments and the other group with two-piece abutments, before and after cyclic loading (n=10 in each group). The initial RTV of the abutment screw was measured with a digital torque meter. Each abutment received a cement-retained metal crown with 30° occlusal surface. Cyclic axial peak load of 75±5 N was applied to the implants for 500,000 cycles at 1 Hz. The post-load RTV was then measured. Two-way and repeated measures ANOVA, and independent t-test were applied to assess the effects of cyclic loading, connection design, abutment type, and their interaction on the percentage of torque loss (α=.05). Two-way ANOVA showed that serration of mating surfaces had a significant effect on torque maintenance before (P<0.001) and after (P=0.004) cyclic loading. Repeated measures ANOVA also showed that loading had a significant effect on the torque loss percentage (P< 0.01). Comparison of the groups with t-test showed that the torque loss of the serrated groups was lower than that of non- serrated groups. Despite the limitations of this study, the stability of the implant-abutment connection in the serrated design was higher than that of non-serrated group.

scholarly journals Implant Volume Loss, Misfit, Screw Loosening, and Stress In Custom Titanium and Zirconia Abutments

2020 ◽  
Vol 31 (4) ◽  
pp. 374-379
Author(s):  
Sales Antônio Barbosa Jr ◽  
Ataís Bacchi ◽  
Valentim Adelino Ricardo Barão ◽  
Yara Teresinha Corrêa Silva-Sousa ◽  
João Felipe Bruniera ◽  
...  
Keyword(s):  
Stress Distribution ◽  
Repeated Measures ◽  
Titanium Implants ◽  
Volume Loss ◽  
Screw Loosening ◽  
Mechanical Cycling ◽  
Torque Wrench ◽  
Significant Difference ◽  
Before And After ◽  
Cad Cam

Abstract The aim of this study was to verify the effect of the implant volume loss, vertical misfit between abutment and prosthetic platform, prosthetic screw loosening torque, and screw stress distribution in titanium and zirconia abutments. Ten CAD/CAM system custom abutments of each material were milled and attached to the titanium implants. The implant volume loss was evaluated by microtomography, the vertical misfit with optical microscopy, and digital torque wrench measured the prosthetic screw loosening. All experimental analyses were performed before and after mechanical cycle (1,000,000 cycles, 100 N/2 Hz). Virtual models of the structures were created for finite element analysis, and the stress on the screw obtained with von Mises procedure. Data were analyzed using an independent t-test, two-way ANOVA for repeated measures, and Tukey’s HSD test (a=0.05). There was no significant difference in the implant volume loss for the two abutment materials (p=0.662). Titanium abutments provided higher loosening torque values after mechanical cycling (p<0.001). Lesser marginal misfit was obtained with titanium abutments before and after mechanical cycling (p<0.001). The stress distribution on the screw was similar between abutment materials. In conclusion, CAD/CAM custom titanium abutment reduced the marginal misfit and increased the torque maintenance of prosthetic screws when compared to CAD/CAM custom zirconia abutment.

scholarly journals Effect of Angle and Type of Customized Abutment (Castable & Cast-to) on Torque Loss and Fracture Resistance After Cyclic Loading

2018 ◽  
Vol 12 (1) ◽  
pp. 987-994
Author(s):  
Moeen Hosseini Shirazi ◽  
Maryam Memarian ◽  
Marzieh Alikhasi ◽  
Somayeh Zeighami
Keyword(s):  
Cyclic Loading ◽  
Repeated Measures ◽  
Fracture Resistance ◽  
Testing Machine ◽  
Chromium Alloy ◽  
Cobalt Chromium ◽  
High Fracture ◽  
Before And After ◽  
Torque Loss ◽  
Rotational Freedom

Background: Implant placement with more than 25° angle and use of customized abutments are still challenging in implant dentistry. Also, casting is still the most commonly used method for fabrication of customized abutments. Objective: This study evaluated the effect of angulation and type of abutment (castable and cast-to) on torque loss and fracture resistance after cyclic loading. Methods: Two implants were mounted with 0 and 30° angle on a gypsum model. Castable and Cast-to abutments were casted by cobalt-chromium alloy on each implant (10 samples in 4 groups). Rotational freedom was measured by a video-measuring microscope. The reverse torque values before and after cyclic loading (500,000 cycles) were measured by a digital torque-meter. Abutments were subjected to fracture resistance test in a universal testing machine. Data were analyzed using the Kruskal Wallis, two-way ANOVA and repeated measures tests. Results: Difference between castable and cast-to abutments regarding rotational freedom was not significant. Torque loss in castable abutments was significantly greater than cast-to abutments before and after cyclic loading (P < 0.05). The effect of abutment angle on torque loss before and after cyclic loading was not significant. Conclusion: Irrespective of the abutment angle, torque loss was significantly higher in castable groups. Considering the high fracture resistance, abutment fractures were not clinically an issue.

scholarly journals Comparing Torque Loss in Standard Implants and Short Implants with Increased Vertical Cantilever Abutments: an In Vitro Study

2020 ◽  
Vol 24 (1) ◽  
Author(s):  
Ezzatollah Jalalian ◽  
Zahra Yousofi
Keyword(s):  
In Vitro Study ◽  
Longitudinal Axis ◽  
Screw Loosening ◽  
Reverse Torque ◽  
Short Implants ◽  
Significant Difference ◽  
Torque Loss ◽  
Student’S T ◽  
Abutment Screw

Objectives: With regard to the prevalence of abutment screw loosening (SL) and bone height reduction, particularly in the posterior regions of the jaws, as well as the contradictory issue of applying short implants instead of surgeries, along with all preparations associated with longer implants, the present study aimed to compare the amount of torque loss in short implants with increased vertical cantilever abutments and standard ones. Material and Methods: In this experimental study, a total number of 20 implants (MegaGen Implant Co., Ltd, South Korea) with 4.5 mm diameter including 10 short implants (7 mm) and 10 standard ones (10 mm) were utilized. Using a surveyor, fixtures were perpendicularly mounted in 13×34 mm resin for short implants and 19×34 mm resin for standard ones. The abutments of the same height but different cuff heights (2.5 mm for the standard implants and 5.5 mm for the short ones) were then tightened with 30 N.cm, via a digital torque meter. To compensate the settling effect, the abutment screw was re-tightened with 30 N.cm after 10 min. Upon applying 500,000 cycles at 75 N.cm and 1 Hz along the longitudinal axis on each sample, blind reverse torque value (RTV) was measured with a digital torque meter. The data were finally analyzed using Student’s t-test. Results: Both groups experienced torque loss, but there was no statistically significant difference between the case and control groups in terms of abutment SL (p = 0451). Conclusion: Short implants seem to be a good mechanical alternative in emergencies with respect to torque loss and abutment SL. KEYWORDS Reverse torque value; Cyclic loading, Short implant; Screw loosening; Crown-implant ratio; Torque loss.

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