Analysis of the sliding mechanics of NBR thread pattern

The objective of the present work is to study materials properties and performance of the footwear thread to develop and implement an analytical-numerical model capable of simulating their performance. The numerical results simulation was carried out, analyzing the sliding mechanisms of shoe-floor and evaluating the contact pressure and vertical stress. An experimental procedure, supported by a numerical model, was implemented for computing the evolution of the tangential force over several load increments.

Comparison of frictional resistance between four types of brackets in combination with stainless steel and beta-titanium archwires

Objectives: The objective of the study was to evaluate and compare the frictional resistance generated by four different types of brackets in combination with stainless steel (SS) and titanium molybdenum alloy (TMA) archwires. Materials and Methods: Maxillary premolar brackets were used in this study. These brackets were divided into eight groups comprising seven samples each. Of the eight groups, four groups were combined with SS and four groups were combined with TMA archwires. The testing was done in the presence of human saliva. The static frictional resistance was calculated for each group. One-way ANOVA and post hoc Tukey tests were done to compare the friction generated by each group. Results: There was a statistically significant difference between the friction generated by the monocrystalline brackets and the other bracket groups (P < 0.001). There was no statistically significant difference in static friction generated between self-ligating and conventionally ligated brackets. There was a statistically significant difference between the frictional resistance produced by SS and TMA wires (P = 0.02) with regard to monocrystalline ceramic brackets only. Conclusion: Monocrystalline ceramic brackets (Radiance) were found to generate the highest frictional resistance during sliding mechanics when compared to other brackets in combination with both SS and TMA wires. Self-ligating brackets did not show a statistically significant reduction in friction when compared to conventional ligation. There was a statistically significant difference between SS and TMA wires when used with monocrystalline brackets.

Micro-osteoperforation effectiveness on tooth movement rate and impact on oral health related quality of life:

ABSTRACT Objectives To investigate the effect of micro-osteoperforation (MOP) on the rate of tooth movement (RTM), space closure duration, and oral health–related quality of life (OHRQoL) during completion of anterior retraction in patients undergoing combined orthodontic-surgical treatment after premolar extraction and decompensation with sliding mechanics. Materials and Methods Twenty-four participants with indications for premolar extractions were randomly allocated to treatment with conventional sliding mechanics (control group; CG) or with to treatment in which three MOPs were performed every activation (experimental group; EG). Dental impressions were taken monthly until space closure was completed and dental casts were converted to three-dimensional models. After the anterior retraction procedure, Oral Health Impact Profile (OHIP-14) questionnaires were filled out at 4 and 72 hours. Results Eighteen patients (7 men and 11 women) remained in the trial until space closure was completed (mean follow-up period = 247 days). For full space closure RTM, no significant difference (P = .492) was found between groups (0.614 mm/month for the CG; 0.672 mm/month for the EG). The RTM for different time points, groups, time frames and their interaction were statistically different (P &lt; .05). In multiple correlation analysis, the RTM significantly decreased over time for both groups (P &lt; .05). The OHRQoL scores were significantly higher (worse) for the EG. The psychological, physical and social disabilities, and handicap domains displayed significant differences between the two groups. Conclusion Use of MOPs did not change the full space closure RTM, while it had a negative impact on OHRQoL.

Comparison of dual-dimensional and rectangular wires in terms of space closure and anchorage loss during retraction with miniimplants: A prospective clinical study

Background . In sliding mechanics, archwires should slide easily during the retraction of anteriors. Round wires slide well, but the torque control is a significant problem. Rectangular wires produce effective torque expression but pose a challenge to free sliding due to factors like friction and force used to overcome friction, etc. To utilize the properties of both wires, the wire should be bi-dimensional. Dual-dimensional wire is one such wire with different dimensions in the anterior and posterior sections. This study aimed to compare the amount of space closure and anchorage loss of molars between the rectangular and dual-dimensional wire groups during retraction with mini-implants. Methods. Forty patients were randomly allocated to two groups (n=20). Patients with rectangular wires formed the control group, and those with dual-dimensional wires formed the experimental group. Mini-implants and NiTi coil springs were used for retraction. Model and cephalometric analyses were carried out to calculate the amount of space closure and anchor loss, before and four months after the study. Statistical significance was set at P<0.05. Results. The average amount of space closure was higher with DDW (3.98 mm) than rectangular wire (3.22 mm). The difference was statistically significant. No significant difference was found with anchorage loss. Conclusion. DDW can be used as an alternative to rectangular wires during retraction with mini-implants; however, it cannot replace the rectangular wires completely. Anchorage control was effective with both wires.

A Novel Temporary Anchorage Device Aided Sectional Mechanics for Simultaneous Orthodontic Retraction and Intrusion

Closing spaces on light wires with inadequate knowledge and inappropriate mechanics can cause a “roller coaster” effect leading to an improper occlusion. Current knowledge of biomechanics, along with the incorporation of TADs, has made this process less challenging and more predictable. Resistance to sliding is considered the most prominent inhibitor of space closure in archwire-guided space closure or sliding mechanics, in turn delaying treatment duration considerably. In our case, resistance to sliding, primarily binding of the wire in the bracket slot, was nullified with the use of loop and sectional mechanics. This case report is aimed at showcasing the successful treatment of a young lady with a novel clinical setup to retract the canines into the premolar extraction space and simultaneously retract and intrude the anterior segment using sectional archwires and TADs in just under nine months. The current setup with sectional wires and TADs produced an uprighting, and an intrusive effect on the upper incisors during space closure. Additionally, the anchorage design avoided any significant change in the vertical dimension during sagittal correction of the Class II malocclusion. The occlusal plane remained almost stable with good amount of uprighting of the lower incisors following lower space closure too. The use of good biomechanical principles helped us achieve all the treatment goals and objectives in a very short period of time.

Resistance to sliding of orthodontic archwires under increasing applied moments

Background: Orthodontic treatment with fixed appliances involves sliding of brackets along archwires. These movements involve friction, which causes resistance to sliding. In addition, moments cause teeth to tip until binding occurs between the bracket and archwire. The manufacturer of a new TiMolium®Titanium archwire claims material properties superior to β-Titanium, potentially leading to reduced resistance to sliding. Objective: To compare TiMolium archwires with β-Titanium and stainless steel archwires as the current gold standard for sliding mechanics under application of an increasing moment. Materials and methods: A total of 120 stainless steel (Smartclip, 3M, Monrovia, CA) and ceramic self-ligating 0.022″-slot brackets (Clarity SL, 3M) were divided into six equal-sized groups. Resistance to sliding was tested with 0.019″ × 0.025″ TiMolium (TP Orthodontics, La Porte, IN), β-Titanium (3M), and stainless steel (3M) archwires using a custom-designed apparatus to simulate sliding mechanics and application of moments of 1000, 2000, and 3000 g-mm. Results: Using stainless steel brackets, the TiMolium archwires had significantly higher resistance to sliding than stainless steel archwires at all moments tested while there was no difference between TiMolium and β-Titanium. Using ceramic brackets, the resistance to sliding with TiMolium archwires was no different than with stainless steel archwires. Both TiMolium and stainless steel archwires showed significantly lower resistance to sliding than β-Titanium. Conclusion: TiMolium archwires have resistance to sliding intermediary to stainless steel and β-Titanium archwires when clinically relevant moments are applied. Used with the stainless steel brackets, they behave like β-Titanium, whereas used with the ceramic brackets, they behave more like stainless steel.

Evaluation of friction on self-ligating and conventional brackets associated with different types of archwires submitted to sliding mechanics

Aim: The aim of this study was to verify the frictional force during sliding mechanics in orthodontic tooth movement, using conventional metal brackets of the active and passive self-ligating types with stainless steel and copper nickel titanium archwires. Methods: This experimental in vitro study was conducted with conventional metal (Morelli, Sorocaba, SP, Brazil) brackets, active self-ligated (SLI Morelli, Sorocaba, SP, Brazil) and passive self-ligated (SLP Morelli, Sorocaba, SP, Brazil), with slot 0.022 x 0.028 inches and Roth prescription. The brackets were tested with rectangular section 0.019 x 0.025 inch copper nickel titanium and stainless steel archwires. For each type of bracket, 10 sets of plate/bracket/archwire segment (n=10) were fabricated. Non-parametric Kruskal Wallis and Dunn tests were used for comparison between types of brackets and Wilcoxon tests for comparison between types of archwires. Results: The results showed that the frictional force values were higher with copper nickel titanium than with stainless steel archwires (p<0.05). When copper nickel titanium archwires were used, the active self-ligating brackets showed higher frictional force values than the other types, followed by the conventional brackets. Lower frictional force values were observed with passive self-ligating brackets. For stainless steel archwires, no difference was observed between conventional and active self-ligating brackets, the passive self-ligating type presented lower frictional force values than the others. Conclusion: It was concluded that the higher frictional force was observed when active self-ligating brackets were associated with copper nickel titanium archwires. Lower frictional force was verified between passive self-ligating brackets combined with stainless steel archwires.