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.

Impact of Resin Composite Viscosity and Fill-technique on Internal Gap in Class I Restorations: An OCT Evaluation

2021 ◽  
Author(s):  
KR Kantovitz ◽  
LL Cabral ◽  
NR Carlos ◽  
AZ de Freitas ◽  
DC Peruzzo ◽  
...  
Keyword(s):  
Repeated Measures ◽  
Resin Composite ◽  
Oral Care ◽  
High Viscosity ◽  
Class I ◽  
Low Viscosity ◽  
Significant Difference ◽  
Before And After ◽  
Internal Adaptation ◽  
Internal Gap

SUMMARY The aim of this in vitro study was to quantitatively evaluate the internal gap of resin composites of high-and low-viscosity used in single- and incremental-fill techniques in Class I cavities exposed to thermal cycling (TC) using optical coherence tomography (OCT). Cavities of 4-mm depth and 3-mm diameter were prepared in 36 third molars randomly distributed into four groups, according to viscosity of restorative resin-based composite (high or low viscosity, all from 3M Oral Care) and technique application (bulk or incremental fill) used (n=9): RC, high-viscosity, incremental-fill, resin-based composite (Filtek Z350 XT Universal Restorative); BF, high-viscosity, bulk-fill, resin-based composite (Filtek One Bulk Fill); LRC, low-viscosity, incremental-fill, resin-based composite (Filtek Z350 XT Flowable Universal Restorative); and LBF, low-viscosity, bulk-fill, resin-based composite (Filtek Flowable Restorative). Single Bond Universal Adhesive system (3M Oral Care) was used in all the experimental groups. The incremental-fill technique was used for RC and LRC groups (2-mm increments), and a single-layer technique was used for BF and LBF groups, as recommended by the manufacturer. The internal adaptation of the resin at all dentin walls was evaluated before and after TC (5000 cycles between 5°C and 55°C) using OCT images. Five images of each restored tooth were obtained. Images were analyzed using ImageJ software that measured the entire length of the gaps at the dentin–restoration interface. The length of gaps (μm) was analyzed using two-way repeated measures ANOVA and the Tukey tests (α=0.05). There was a significant interaction between material types and TC (p=0.006), and a significant difference among all material types (p&lt;0.0001), before and after TC (p&lt;0.0001). Increased internal gaps at the dentin–restoration interface were noticed after TC for all groups. RC presented the lowest value of internal gap before and after TC, while LBF showed the highest values of internal gap after TC. In conclusion, TC negatively affected the integrity of internal gap, whereas high-viscosity, incremental-fill, resin-based composite presented better performance in terms of internal adaptation than low-viscosity, bulk-fill materials in Class I cavities.

Postural control and risk of falling in people who are blind: The effect and durability of perturbation and vestibular exercises

2022 ◽  
pp. 026461962110673
Author(s):  
Yousof Moghadas Tabrizi ◽  
Mohammad Hani Mansori ◽  
Mohammad Karimizadeh Ardakani
Keyword(s):  
Repeated Measures ◽  
Dynamic Balance ◽  
Somatosensory System ◽  
Exercise Group ◽  
Risk Of Falling ◽  
Balance System ◽  
Significant Difference ◽  
Before And After ◽  
Post Test ◽  
Falling Risk

The aim of this study was to compare the effect and durability of perturbation and vestibular exercises on balance and the risk of falling in people with visual impairment (VI). Thirty-six men with VI were divided into three groups, including a control and two experimental (perturbation and vestibular) groups. The experimental groups performed perturbation and vestibular exercises for 4 weeks and three sessions per week. Biodex balance system was used to assess balance and falling risk before and after training interventions. To evaluate the effects within and between groups at three levels of measurement: pre-test, post-test, and durability effect between three groups, repeated measures analysis of variance (ANOVA) and one-way ANOVA were used. Repeated measures ANOVA test showed that both experimental groups showed significant improvements in static balance, dynamic balance, and falling risk. In comparison between the groups, the results showed that in the post-test and durability stages, there was a significant difference between the groups and the perturbation exercise group had a greater effect on the dependent variables. Due to the effectiveness of exercises, it is recommended that people with VI pay attention to balance-based perturbation exercises to strengthen the somatosensory system and vestibular exercises to strengthen the vestibular system.

scholarly journals Hearing Thresholds Changes after MRI 1.5T of Head and Neck

2019 ◽  
Vol 2019 ◽  
pp. 1-4 ◽  
Author(s):  
Maryam Bahaloo ◽  
Mohammad Hossein Davari ◽  
Mohammad Sobhan ◽  
Seyyed Jalil Mirmohammadi ◽  
Mohammad Taghi Jalalian ◽  
...  
Keyword(s):  
Head And Neck ◽  
High Frequency ◽  
Repeated Measures ◽  
Hearing Threshold ◽  
Significant Shift ◽  
Auditory Thresholds ◽  
Hearing Thresholds ◽  
High Frequency Audiometry ◽  
Significant Difference ◽  
Before And After

Introduction. Exposure to high intensity noise produced by MRI is a cause for concern. This study was conducted to determine the temporary and permanent effects of exposure to noise created by performing MRI on the hearing threshold of the subjects using conventional and extended high frequency audiometry. Methods. This semiexperimental study was performed on 35 patients referred to Shahid Rahnemoun Hospital for head and neck MRI due to different clinical conditions. The hearing threshold of patients was measured before, immediately after, and 24 hours after performing 1.5 Tesla MRI using conventional and extended high frequency audiometry. SPSS version 18 was used to compare the mean hearing thresholds before and after MRI using paired T test and repeated measures analysis. Results. Comparison of auditory thresholds in conventional and extended high frequencies before and immediately after MRI showed a significant shift at 4 KHz (P = 0.008 and P = 0.08 for right and left ears), 6 KHz (P = 0.03 and P = 0.01 for right and left ears), and 14 KHz (P =0.03 and P = 0.31 for right and left ears). However, there was no significant difference between audiometric thresholds before and 24 hours after MRI. Conclusion. Noise due to 1.5 Tesla MRI can only cause transient threshold shift.

Treatment of Objective and Subjective Benign Paroxysmal Positional Vertigo

2013 ◽  
Vol 24 (07) ◽  
pp. 600-606 ◽  
Author(s):  
Alexandra C. Huebner ◽  
Susan R. Lytle ◽  
Steven M. Doettl ◽  
Patrick N. Plyler ◽  
James T. Thelin
Keyword(s):  
Repeated Measures ◽  
Benign Paroxysmal Positional Vertigo ◽  
Head Position ◽  
Subjective Report ◽  
Repeated Measures Design ◽  
Positional Vertigo ◽  
Data Collection And Analysis ◽  
Significant Difference ◽  
Before And After ◽  
Paroxysmal Positional Vertigo

Background: Benign paroxysmal positional vertigo (BPPV) is the most common cause of vertigo in adults and is a result of otolithic particles or debris that become free floating within a semicircular canal or adhere to the cupula. Characteristics of BPPV include brief episodes of latent onset vertigo that occur with changes in head position, transient rotary nystagmus beating toward the dependent ear, and reversed nystagmus upon sitting up. Both the vertigo and nystagmus fatigue quickly while maintaining the same head position. The BPPV may be classified as objective or subjective. Objective BPPV presents all the aforementioned symptoms whereas subjective BPPV presents all the symptoms without nystagmus. The accepted method of treatment for objective BPPV is canalith repositioning maneuvers (CRM); however, CRM are not traditionally used as the method of treatment for cases of subjective BPPV. Purpose: The purpose of the study was to determine if the subjective report of dizziness using the Dizziness Handicap Inventory (DHI) was different in patients with objective and subjective BPPV and to determine if the two groups showed similar improvements in perceived dizziness handicap following CRM treatment. Research Design: The present study utilized a retrospective, repeated measures design. Study Sample: Sixty-three adults with BPPV that were given the DHI both before and after CRM treatment. Data Collection and Analysis: Pre and post DHI results were analyzed for participants with objective versus subjective BPPV. A five-question DHI subscale was also analyzed between the groups. Results: A significant difference was noted between initial and posttreatment DHI scores for patients in both the subjective and objective groups when using the full-scale and subscale DHI. No significant difference was noted between groups for their initial or posttreatment DHI scores. The two groups also did not differ significantly in their initial or posttreatment DHI subscale scores. Conclusions: The results of the study indicated that individuals with both objective and subjective BPPV demonstrated significant improvement in DHI scores following CRM treatment. Additionally, there was no difference in DHI improvement for the subjective versus objective group suggesting CRM are effective for both subjective BPPV and objective BPPV. This improvement in DHI scores was also noted in the five-question DHI subscale with no significant difference noted between groups. These findings combined with previous studies suggest the presence or absence of nystagmus during Dix-Hallpike maneuvers is not related to the effectiveness of treatment using CRM.

scholarly journals Marginal Adaptation of Implant Prostheses Fabricated by Different Materials in Excessive Crown Height Space Before and After Veneering

2021 ◽  
Author(s):  
Safoura Ghodsi ◽  
Marzieh Alikhasi ◽  
Majid Sahebi ◽  
Vahideh Nazari
Keyword(s):  
Repeated Measures ◽  
Marginal Adaptation ◽  
Crown Height ◽  
Second Molar ◽  
Basic Model ◽  
Nickel Chromium ◽  
Significant Difference ◽  
Before And After ◽  
Marginal Discrepancy ◽  
To Receive

Objectives: This study aimed to investigate the marginal adaptation of implant-supported three-unit fixed restorations fabricated in excessive crown height by various frameworks namely zirconia, nickel-chromium (Ni-Cr) alloy, and Polyetheretherketone (PEEK) before and after veneering. Materials and Methods: A basic model with two implant fixtures was made to receive posterior three-unit fixed partial dentures (second premolar to second molar) in 15 mm crown height. A total of 30 frameworks were fabricated using Ni-Cr, zirconia, and PEEK (n=10). All specimens were veneered and vertical marginal discrepancy was evaluated before and after veneering using a stereomicroscope (×75). The effect of framework material and veneering on marginal discrepancy was evaluated by repeated-measures and one-way ANOVA, and paired t test (α=0.05). Results: There was a significant difference between the groups (P<0.001) before and after veneering. The vertical marginal discrepancy of zirconia frameworks was significantly lower than that of other groups both before and after veneering (P<0.001). Statistical analysis revealed that the veneering process had a significant effect on marginal adaptation (P<0.001). Conclusion: In implant prostheses with excessive crown height, zirconia had the greatest marginal adaptaion significantly, followed by Ni-Cr. Veneering caused a significant increase in marginal discrepancy of all the materials.

scholarly journals In vitro study of marginal, internal and proximal adaptation of implant-supported single-crown CAD/CAM restorations

2020 ◽  
Vol 19 ◽  
pp. e207286
Author(s):  
Kamila Aguiar Figueiredo Alves ◽  
Janaina Emanuela Damasceno ◽  
Viviane Maia Barreto de Oliveira ◽  
Luiz Gustavo Cavalcanti Bastos ◽  
Andrea Nóbrega Cavalcanti
Keyword(s):  
Repeated Measures ◽  
T Test ◽  
Digital Impression ◽  
Single Crown ◽  
Significant Difference ◽  
Cad Cam ◽  
Student’S T ◽  
One Way Anova ◽  
Student’S T Test

Aim: This study evaluated the precision of a CAD/CAM system by measuring marginal, internal and proximal fits in implantsupported single-crown restorations. Methods: Ten models of the upper arch were made in which implants replaced the upper left premolars. For fabrication of the zirconia infrastructures, titanium bases (TiBase) were coded and scanned using a scan body. A second digital impression was made for the fabrication of prostheses. Silicone impression material was used to determine the internal clearance between the TiBase and infrastructure and between the infrastructure and crown, whose thickness was measured at three points [P1 (cervical), P2 (middle) and P3 (occlusal)] with a stereoscopic microscope at 70x and 100x magnification. One-way ANOVA for repeated measures and the Student t-test were used for the analysis of internal and marginal adaptation. Proximal contacts were analyzed qualitatively. Results: There was no significant difference between the teeth evaluated (Student’s t-test; p>0.05) or between the corresponding points evaluated in either tooth (one-way ANOVA; p>0.05). Analysis of the internal clearance between the infrastructure and crown demonstrated that all points were significantly different compared to the reference standardized at 100 μm (Student’s t-test p<0.0001). There was no significant difference between P1 and P2, with the thickness at these two points being lower than that obtained at P3 (one-way ANOVA, p<0.05). The proximal contacts did not coincide with the quality defined by the device. Conclusion: The system tested was unable to produce implantsupported single-crown ceramic restorations with marginal, internal and proximal fits matching the digital workflow, with the inferior fits requiring adjustment prior to cementation.

scholarly journals Different fabrication techniques of implant-supported prostheses

2019 ◽  
Vol 18 ◽  
pp. e191573
Author(s):  
Silas Monteiro Borges ◽  
Stephanie Francoi Poole ◽  
Izabela Cristina Maurício Moris ◽  
Aloísio Oro Spazzin ◽  
Adriana Cláudia Lapria Faria ◽  
...  
Keyword(s):  
Mechanical Behavior ◽  
Computer Aided Design ◽  
Fracture Load ◽  
Fracture Pattern ◽  
Thermomechanical Cycling ◽  
Significant Difference ◽  
Computer Aided ◽  
Before And After ◽  
Cad Cam ◽  
Manufacturing Techniques

Aim: This study evaluated the mechanical behavior of implant-supported crowns obtained by different fabrication technique after thermomechanical cycling. Methods: Thirty-two external hexagon dental implants were divided into four groups (n=10): CC – conventional casting with torch; EI – electromagnetic induction casting; PL – plasma casting; and CAD-CAM – milling through computer-aided design and computer-aided manufacturing. Vickers microhardness of the specimens were made before and after the thermomechanical cycling, and then subjected to fracture load. Fracture pattern was evaluated. Results: No significant difference was observed comparing the microhardness before and after thermomechanical cycling. CAD-CAM group presented significant lower microhardness than the other groups. No significant statistical difference was showed on fracture load between the groups. The CAD-CAM and PL presented lower number of failure by plastic deformation. Conclusion: The manufacturing techniques affected the mechanical behavior and the failure pattern of implant-supported crowns tested.

Effects of Polishing versus Glazing on Dental Ceramic Wear: A Comparative In Vitro Study

2021 ◽  
Vol 11 (1) ◽  
pp. 73-79
Author(s):  
Mohammed Abujalala ◽  
A. Nehir Özden
Keyword(s):  
Wear Behavior ◽  
In Vitro Study ◽  
Ceramic Materials ◽  
Volume Loss ◽  
Dental Ceramic ◽  
Chewing Simulation ◽  
System A ◽  
Before And After ◽  
Cad Cam

This study analyzed the wear behavior caused by steatite antagonists to four dental ceramic materials, comparing this between two surface treatments: polishing and glazing. Methods: Thirty flat samples (10 × 8 × 2 mm) were prepared from each of four ceramics: IPS e. max CAD (IPS), GC Initial LiSi Press (LP), Vita Enamic (VE), and monolithic zirconia (MZ). Subgroups of samples were finished by polishing or glazing or neither (as controls). The samples were subjected to computer-controlled chewing simulation (240,000 cycles of 49 N at 1.6 Hz, with thermocycling at 5/55 C), with steatite balls as antagonists. The samples and antagonists were visualized before and after the test with a laser abrasion measurement system, a CAD/CAM scanner, and electron microscopy scanning, and the volumes lost from the tested samples and antagonists were analyzed. Results: For the MZ samples, the polished samples showed significantly less volume loss than the glazed samples (0.0200 mm3 vs. 0.0305 mm3; p =0.0001), whereas there was significantly greater antagonist volume loss (0.0365 mm3 vs. 0.0240 mm3; p = 0.011). There were no significant differences between the subgroups for IPS, VE, and LP, although antagonist volume losses were non-significantly greater with the glazed samples than with the polished samples. Conclusions: Polishing MZ had adverse effects on the corresponding antagonist wear. Glazed MZ showed the lowest antagonist wear.

scholarly journals Effect of Mechanical Cycling on Screw Torque in External Hexagon Implants with and without Platform Switching

2015 ◽  
Vol 26 (3) ◽  
pp. 284-287 ◽  
Author(s):  
Bruno Andrade Cantharino de Carvalho ◽  
Eduardo Vedovatto ◽  
Paulo Sérgio Perri de Carvalho ◽  
José Vitor Quinelli Mazaro ◽  
Rosse Mary Falcón-Antenucci
Keyword(s):  
In Vitro Study ◽  
Screw Loosening ◽  
Removal Torque ◽  
Tukey Test ◽  
Reverse Torque ◽  
Mechanical Cycling ◽  
Significant Difference ◽  
Platform Switching ◽  
Abutment Screw

This in vitro study evaluated the effect of mechanical cycling on the torque of retaining screw in external hexagon implants with platform switching (PS), regular platform (RP) and wide platform (WP). A total of 30 specimens were equally divided into 3 groups: PS, PR and WP. Each specimen was prepared with implants: 3.75 x 10 mm for RP group and 5.0x10 mm for PS and WP groups and its respective abutment with 32 Ncm torque. All groups were subjected to 106 cycles with 100 N (corresponding to about 40 months of chewing). The results were obtained with the reverse torque of each specimen and data were evaluated using ANOVA and Tukey test (p<0.05). The PS group showed statistically significant difference in screw removal torque (30.06±5.42) compared with RP (23.75±2.76) and WP (21.32±3.53) (p<0.05) groups; the RP and WP groups showed no statistically significant difference between them. It was concluded that the PS group showed higher reverse torque value, suggesting lower susceptibility of the abutment screw loosening.

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