scholarly journals Structural resistance of orthodontic mini-screws inserted for extra-alveolar anchorage

2021 ◽  
Vol 34 (1) ◽  
pp. 27-34
Author(s):  
Carlos Vieira ◽  
Francyelle Pires ◽  
Wallisen Hattori ◽  
Cleudmar de Araújo ◽  
Marcelo Garcia-Junior ◽  
...  
Keyword(s):  
Stainless Steel ◽  
In Vivo Studies ◽  
Scanning Electron Microscopy Data ◽  
Insertion Angle ◽  
Electron Microscopy Data ◽  
Alloy Type ◽  
Structural Resistance ◽  
Microscopy Data ◽  
Post Hoc

The risk of fracture or strain in mini-screws is higher if diameter, length, type of alloy or insertion angle is selected inappropriately. The aims of this study were to test the structural resistance of two types of orthodontic mini-screws –one made of stainless steel and another of titanium– from an international brand and to evaluate the efficacy of two other titanium miniscrews of Brazilian origin, during an extra-alveolar anchorage procedure. The mini-screws analyzed were: Bomei stainless steel and Bomei titanium / Taiwan, Morelli titanium and Neodent titanium/ Brazil. Experiments were conducted on pig mandibles to simulate the process of extra-alveolar anchorage. Two insertion processes were used: Direct at 30º, and Indirect, starting at 60º and ending at 30º with gradual continuous movement. Strain was evaluated using Optical and Scanning Electron Microscopy. Data were evaluated using Kruskal-Wallis non-parametric statistical analysis and post hoc Tamhane test. Significant statistical differences in strain were observed among the mini-screws used in the extra-alveolar insertions, both for the direct and indirect procedures. In the indirect insertion tests, both stainless steel and titanium mini-screws suffered deformation, showing that angling can be an important factor in mini-screw failure rates. The change in angle during the insertion movement increased deformation rates independently of alloy type, increasing the risk of failure. These results could help orthodontists in choosing mini-screws for extra-alveolar anchorage, which can be performed with direct or indirect insertion. In vivo studies should be conducted to confirm the findings of this study.

The Effect of Bioceramic Surface Modifications on Different Endosseous Implant and Surgical Design. A Series of In Vivo Studies in Dogs.

2008 ◽  
Vol 396-398 ◽  
pp. 385-388
Author(s):  
Paulo Guilherme Coelho ◽  
Marcelo Suzuki
Keyword(s):  
Close Contact ◽  
In Vivo Studies ◽  
Implant Design ◽  
Implant Surface ◽  
Intimate Contact ◽  
Endosseous Implant ◽  
Level Of Significance ◽  
Post Hoc ◽  
Appositional Bone

The objective of this series of experiments was to evaluate the effect of bioceramic coatings/ incorporations on implant surfaces as a function of implant and surgical drilling design. Methods: A series of four in vivo studies were conducted utilizing the dog proximal tibia model. The models provided implants that remained from 2 to 5 weeks implantation time. The different studies comprised the placement of implants with intimate contact with bone following placement and implant designs that resulted in healing chambers. The various implant types presented surfaces with and without Ca- and P-based bioceramic incorporations. Biomechanical and histomorphometric measurements along with qualitative bone-implant interface morphology evaluation were performed. For all studies, one-way ANOVA at 95% level of significance was employed along with Tukey's post-hoc multiple comparisons. Results: Close contact between cortical and trabecular bone and all the different implant surfaces irrespective of implant fit (with and without healing chambers) showed that all surfaces were biocompatible and osteoconductive. In general, appositional bone healing was observed at all implant regions that were in intimate contact with bone immediately after placement, and an intramembranous-like healing occurred throughout the whole volume of the healing chambers. Irrespective of implant + surgical drilling design, the presence of Ca and P resulted in a bone morphology that showed primary osteonic structures at earlier times than uncoated surfaces. Conclusion: Irrespective of implant design and surgical drilling combination, the presence of Ca and P on the implant surface positively modulated early healing around endosseous implants.

Fractographic Regularities in Fatigue Failure of 17Mn1Si Steel

2014 ◽  
Vol 1040 ◽  
pp. 230-235
Author(s):  
Pavlo Maruschak ◽  
Sergey Panin ◽  
Ilya Vlasov ◽  
Iryna Danyliuk ◽  
Roman Bishchak
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Scanning Electron Microscopy Data ◽  
Structural Level ◽  
Deformation And Failure ◽  
Leading Role ◽  
Electron Microscopy Data ◽  
Microscopy Data ◽  
Scanning Electron

Using the scanning electron microscopy data the main regularities of the fatigue crack propagation in the 17Mn1Si steel were studied. Based on fracture surface observation and analysis one can testify that the transition of the leading role of deformation and failure from the lower structural level to the higher one has the ordered pattern.

scholarly journals In vivo orthodontic retainer survival - a review

2015 ◽  
Vol 88 (3) ◽  
pp. 298-303 ◽  
Author(s):  
Anca Victoria Labunet ◽  
Mîndra Badea
Keyword(s):  
Stainless Steel ◽  
Survival Rate ◽  
Glass Fiber ◽  
Composite Resin ◽  
Steel Wire ◽  
In Vivo Studies ◽  
Fiber Reinforced Composite ◽  
Reinforced Composite ◽  
Glass Fiber Reinforced

AbstractBackground. Relapse following orthodontic treatment is a constant concern of orthodontists. Fixed retention is preferred especially for the lower arch by most orthodontists.Objectives:. This review focuses on in vivo studies. The main objective is to determine the survival rate of different types of retainer: glass-fiber reinforced composite resin, polyethylene or multistrand stainless steel wire bonded to each tooth from canine to canine in the mandibular arch. A second objective is to assess which of these types is less likely to cause additional problems and the third objective is to evaluate the factors that may influence retainer survival.Results and conclusions. There were 8 studies identified that matched the objectives stated. Curent in vivo studies on survival rate take little notice of the role of the material used for bonding of the fixed retainer. It is not possible to draw a conclusion on reliability of new types of retainers glass fiber reinforced composite resin or polyethylene compared to multistrand stainless steel wire. The multistrand wire remains the gold standard for fixed retention.Although it is a logical outcome that retainer survival is dependent on the application technique, there seems to be no research outcome proving that operator experience, moisture control are essential, nor does patient age or sex have statistically proven effects on survival rates.Adequate studies that involve such aspects should be performed.

scholarly journals Influence of Implant Connection, Abutment Design and Screw Insertion Torque on Implant-Abutment Misfit

2020 ◽  
Vol 9 (8) ◽  
pp. 2365
Author(s):  
Jorge Vélez ◽  
Jesús Peláez ◽  
Carlos López-Suárez ◽  
Rubén Agustín-Panadero ◽  
Celia Tobar ◽  
...  
Keyword(s):  
Insertion Torque ◽  
Scanning Electron Microscopy Data ◽  
Test Results ◽  
Tightening Torque ◽  
Screw Insertion ◽  
Electron Microscopy Data ◽  
Implant Abutment ◽  
External Connection ◽  
Microscopy Data ◽  
One Way Anova

Background: An accurate fit at the implant-abutment interface is an important factor to avoid biological and mechanical complications. The aim of this study was to evaluate the marginal misfit at the implant-abutment interface on external and Morse taper connection, with straight and angulated abutments under different insertion torque loads. Materials and Methods: A total of 120 implants were used, 60 with external connection (EC) and 60 with Morse taper connection (IC). Straight (SA) (n = 60) and angulated abutments (AA) (n = 60) were randomly screwed to each connection at different torque levels (n = 10 each): 10, 20 and 30 Ncm. All specimens were subjected to thermal and cyclic loading and the misfit was measured by scanning electron microscopy. Data were analyzed with one-way ANOVA, t-test and Kruskal-Wallis test. Results: Significant differences (p < 0.001) were found between connections and abutments regardless of the torque applied. Morse taper connections with straight and angulated abutments showed the lowest misfit values (0.6 µm). Misfit values decreased as torque increased. Conclusions: The misfit was affected by the type of connection. The type of abutment did not influence the fit in the Morse taper connection. The higher the tightening torque applied the increase in the fit of the implant-abutment interface.

Tubule Density and Diameter in Coronal Dentin from Primary and Permanent Human Teeth

2013 ◽  
Vol 19 (6) ◽  
pp. 1445-1449 ◽  
Author(s):  
Tathiane L. Lenzi ◽  
Camila de Almeida B. Guglielmi ◽  
Victor E. Arana-Chavez ◽  
Daniela P. Raggio
Keyword(s):  
Repeated Measures ◽  
Primary Teeth ◽  
Permanent Teeth ◽  
Scanning Electron Microscopy Data ◽  
Dentinal Tubule ◽  
Human Teeth ◽  
Deep Layers ◽  
Microscopy Data ◽  
Post Hoc ◽  
Tubule Diameter

AbstractThis study compared dentinal tubule density and diameter of human primary and permanent teeth at different depths of the coronal dentin. Crowns of eight primary second molars and eight permanent third molars were serially sectioned into three disks of ~0.5 mm thickness (superficial, middle, and deep layers), perpendicular to the long axis. Tubule density and diameter were evaluated in 2,000× and 3,000× magnifications by scanning electron microscopy. Data obtained were subjected to two-way repeated measures ANOVA and Tukey's post hoc test (α = 0.05). Tubule density was greater in primary teeth compared with permanent ones, regardless of depth (primary: 124,329 ± 43,594 mm2; permanent: 45,972 ± 21,098 mm2). In general, the tubule density increased as the dentin depth increased, except to the superficial and middle layers from permanent teeth. Tubule diameter was larger in the dentin layer close to the pulp chamber (superficial: 2.4 ± 0.07 μm; middle: 3.70 ± 0.06 μm; deep: 4.28 ± 0.04 μm). No difference was observed between primary (3.48 ± 0.81 μm) and permanent teeth (3.47 ± 0.73 μm). The tubule diameter increases as the dentin depth increases for primary and permanent teeth; however, the tubule density is higher in primary teeth.

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