BACKGROUND: The application of direct current can have a significant impact on the rate of tooth movement and surrounding periodontal ligament collagen turnover. This study aims to provide insight into the optimal characteristics of applied current to achieve enhanced tissue response.
METHODS: Eighteen male Wistar rats were divided into three groups (I, II, and III). Split mouth design was used, and each side was allocated into an experimental group or control group. Experimental sides of groups I, II, and III received 20, 10, and 15 μA of current (15 min, twice daily for 3 days). Both the experimental and control groups receive an orthodontic force via the NiTi closed coil spring. The amount of tooth movement was determined daily. Immunohistochemistry slides were scored using the immunoreactive scoring (IRS) system for collagen types I and III. One-way Analysis of Variance (ANOVA) and Tukey post hoc test were used to analyse the rate of tooth movement, while Mann-Whitney test was used to analyse IRS distribution between control and experimental groups.
RESULTS: Compared with the control group, there was a statistically significant difference in tooth movement in all the experimental groups, with group 3 showing the maximum rate on days 2 and 3. This was supported by immunoreactive scores for both collagen types I and III.
CONCLUSIONS: After 72 hours, the expression of collagen types 1 and 3 increased significantly for group III. This finding was in harmony with the rate of tooth movement, which was maximum for group 3 (15 μA) as compared to other groups.

OBJECTIVE: This study aimed to compare the insertion torque (IT), flexural strength (FS) and surface alterations between stainless steel (SS-MIs) and titanium alloy (Ti-MIs) orthodontic mini-implants.
METHODS: Twenty-four MIs (2 x 10 mm; SS-MIs, n = 12; Ti-MIs, n = 12) were inserted on artificial bone blocks of 20 lb/ft3 (20 PCF) and 40 lb/ft3 (40 PCF) density. The maximum IT was recorded using a digital torque meter. FS was evaluated at 2, 3 and 4 mm-deflection. Surface topography and chemical composition of MIs were assessed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDS). General linear and mixed models were used to assess the effect of the MI type, bone density and deflection on the evaluated outcomes.
RESULTS: The IT of Ti-MIs was 1.1 Ncm greater than that obtained for the SS-MIs (p= 0.018). The IT for MIs inserted in 40 PCF test blocks was 5.4 Ncm greater than that for those inserted in 20 PCF test blocks (p < 0.001). SS-MIs inserted in higher density bone (40 PCF) had significantly higher flexural strength than the other groups, at 2 mm (98.7 ± 5.1 Ncm), 3 mm (112.0 ± 3.9 Ncm) and 4 mm (120.0 ± 3.4 Ncm) of deflection (p< 0.001). SEM evidenced fractures in the Ti-MIs. EDS revealed incorporation of 18% of C and 2.06% of O in the loaded SS-MIs, and 3.91% of C in the loaded Ti-MIs.
CONCLUSIONS: Based on the findings of this in vitro study, it seems that SS-MIs offer sufficient stability and exhibit greater mechanical strength, compared to Ti-MIs when inserted into higher density bone.

OBJECTIVE: To evaluate and compare the formation of dentinal defects using hand Hedstrom files, XP-Shaper, TruNatomy, and Reciproc Blue file systems when used for oval shaped root canals.
METHODS: One hundred and five extracted human mandibular premolars with single root and oval canals were selected for the study. Twenty-one teeth were unprepared (control), and the remaining teeth were divided into the prepared groups (n = 21), that is, Group H-Files, Group XP-Shaper, Group TruNatomy, and Group Reciproc Blue. All selected teeth were de-coronated perpendicular to the long axis of the tooth by using a diamond-coated disk with water cooling, leaving root segments approximately 16 mm in length. Each group was prepared according to the above file system. Then all roots were sectioned perpendicular to their long axes at 3, 6, and 9 mm from the apex using a diamond-coated disk under a continuous water stream. Each specimen was then checked for the presence of dentinal defects/microcracks.
RESULTS: The XP-Endo shaper group had the lowest number of defects (01/21 roots) 4.7%; TN (04/21) 19%, H-Files (04/21) 19%, and RC Blue (05/21) 23.8% had the highest incidence of defects. However, no significant difference was detected among these groups (P > 0.05).
CONCLUSIONS: The motor-driven root canal instrumentation with rotary and reciprocating files and hand files may create microcracks in the radicular dentine, whereas the XP-Shaper file system produces minimal or less cracks compared to other tested rotary file systems and H-file instrumentation.

The aim of this study was to evaluate how preset torque settings influence the torque, vertical force, and root canal-centering ability of ProGlider and ProTaper NEXT nickel-titanium rotary instruments in canals with different curvature locations. Based on micro-computed tomography, mesial roots of human mandibular molars (25°-40° curvature) were allocated to the apical curvature (apical 1-5 mm) or the middle curvature (apical 5-9 mm) groups, and mandibular incisors (curvature <5°) to the straight canal group. Each group was subjected to automated instrumentation and torque/force measurement with the preset torque of 1, 2.5, or 5 N•cm. Canal-centering ratios were determined with micro-computed tomography. Instrument fracture occurred only in the 2.5 and 5 N•cm groups in curved canals. The preset torque setting and curvature location did not influence canal shaping ability.

To evaluate the three-dimensional (3D) stability and accuracy of additively manufactured surgical templates fabricated using two different 3D printers and materials.
Forty surgical templates were designed and printed using two different 3D printers: the resin group (n = 20) used a digital light processing (DLP) 3D printer with photopolymer resin, and the metal group (n = 20) employed a selective laser melting (SLM) 3D printer with titanium alloy. All surgical templates were scanned immediately after production and re-digitalized after one month of storage. Similarly, the implant simulations were performed twice. Three-dimensional congruency between the original design and the manufactured surgical templates was quantified using the root mean square (RMS), and the definitive and planned implant positions were determined and compared.
At the postproduction stage, the metal templates exhibited higher accuracy than the resin templates (p < 0.001), and these differences persisted after one month of storage (p < 0.001). The resin templates demonstrated a significant decrease in three-dimensional stability after one month of storage (p < 0.001), whereas the metal templates were not affected (p > 0.05). No significant differences in implant accuracy were found between the two groups. However, the resin templates showed a significant increase in apical and angular deviations after one month of storage (p < 0.001), whereas the metal templates were not affected (p > 0.05).
Printed metal templates showed higher fabrication accuracy than printed resin templates. The three-dimensional stability and implant accuracy of printed metal templates remained unaffected by one month of storage.
With superior three-dimensional stability and acceptable implant accuracy, printed metal templates can be considered a viable alternative technique for guided surgery.

BACKGROUND: The aim of this study was to assess the interaction between a 0.019×0.025-inch (″) stainless steel archwire and two types of passive self-ligating brackets with the same slot height (0.022″) and different slot depths (0.028″ and 0.026″, and to measure the archwire/slot play as well as to compare the torque expression with archwire torsions of 12°, 24°, and 36°.
METHODS: An experimental device was developed along with a universal testing machine to measure torque expression in two types of brackets with 0.028″ and 0.026″ slot depths. Analysis of variance (ANOVA) and Tukey\'s test were performed to identify the differences between groups.
RESULTS: The 0.026″ slot bracket presented greater archwire/slot play when compared to the 0.028″ bracket. Torque expression with torsions of 24° and 36° were significantly higher in the 0.028″ depth brackets when compared to the 0.026″ depth brackets.
CONCLUSIONS: The 0.022″×0.026″ passive self-ligating brackets attached with a 0.019″×0.025″ stainless steel archwire provided no greater torque control when compared to 0.022″×0.028″ passive self-ligating brackets.

The purpose of the study is to evaluate the influence of the pecking motion (reciprocal axial motion) surgical technique on the durability behaviour of the Nickel-Titanium endodontic files using Finite Element Analysis (FEA). A commonly used endodontic file, ProTaper Universal F2, is selected for the study. Root canal treatment procedure is simulated on a test-bench (simulated root canal) proposed by G. Gambarini for cyclic fatigue loading of endodontic files with and without the pecking motion via FEA. The hysteresis energy density is used as evaluation criteria for low cycle fatigue life estimation of Shape Memory Alloy files. In an additional study, the root canal treatment procedure is also simulated for an FEA model of a molar tooth with significant root canal curvature to understand the influence of the realistic curvature of a root canal on the fatigue behaviour of endodontic files. For the simulated root canal, analysis accurately predicts the endodontic file\'s failure location, and fatigue life estimation based on the hysteresis energy density is shown to increase significantly with the introduction of the pecking motion, an observation confirmed by reported experimental results. Molar tooth simulations reveal greater file fatigue resistance than in simulated root canals, confirming the pecking motion\'s efficacy in enhancing file durability, even in real root canal conditions. Simulations indicate that the pecking motion technique increases the fatigue life of endodontic files for simulated as well as real root canals and the hysteresis energy is confirmed as an acceptable parameter to quantify fatigue life of Nickel-Titanium endodontic files.

The purpose of the current in vitro study was to evaluate the surface roughness and hardness of three brands of as-received esthetic coated NiTi archwires and compare them with the same parameters after immersion in artificial saliva.
Three groups of 0.016 × 0.022 inch epoxy-coated NiTi orthodontic wires [Tooth tone coated NiTi (Ortho Technology, West Columbia, USA), EverWhite NiTi (American Orthodontics, Wisconsin, USA) and Nitanium Super Elastic Tooth Tone Plastic coated (Ortho Organizers, San Marcos, CA, USA)] were compared. Each group was subdivided into five as-received archwire specimens and five archwire specimens retrieved following immersion in artificial saliva for 28 days. Atomic force microscopy was used for analysis of average surface roughness (Sa). Hardness testing was performed using Digital Vickers hardness tester. ANOVA and Kruskal-Wallis tests were used for comparing the wire groups.
The ranking of (Sa) values was as follows: Nitanium Ortho Organizers > Everwhite American Orthodontics > Tooth tone Ortho Technology (P > 0.05). Nitanium Ortho Organizers archwires showed significantly greater (Sa) than both other groups following immersion in saliva (P < 0.001). The coating hardness of as-received and post-immersion archwires from Tooth tone Ortho Technology was significantly lower than the other groups (P < 0.001). For all the three types of archwires, the mean hardness of immersed wires was significantly lower than that of the as-received archwires (P < 0.001).
Esthetic coated archwires have shown unpleasant surface changes following exposure to artificial saliva. These surface changes are affected by physical characteristics such as surface roughness and hardness of the coating.

BACKGROUND: This study aimed to compare tubular coaxial-NiTi and copper-NiTi orthodontic aligning archwires in terms of teeth alignment, patients\' pain perception, and root resorption.
METHODS: Orthodontic patients aged 12 years or older, having Little\'s irregularity index (LII) of 5-9mm were randomly allocated to either the copper-NiTi group or tubular coaxial-NiTi group with a 1:1 allocation ratio. The archwire sequence was 0.014-inch followed by 0.018-inch for the copper-NiTi group and 0.016-inch followed by 0.018-inch for the tubular coaxial-NiTi group. Each archwire was left in place for eight weeks before progressing to the next size. Good quality impression for the lower arch before treatment (T0) and thereafter every 4 weeks up to 16 weeks was taken to measure LII. Evaluation of pain perception was performed using a visual analog scale (VAS) during the first week following each archwire insertion. Assessment of root resorption was undertaken at T0 and after 16 weeks by taking periapical radiographs for mandibular central incisors using the long cone paralleling technique.
RESULTS: A total of 33 patients were randomized and selected for participation. Of those, 31 patients with a mean age of 15.45±2.22 who completed the trial were included in the analyses (15 patients in the copper-NiTi group and 16 patients in the tubular coaxial-NiTi group). In both groups, the irregularity index significantly decreased after 16 weeks of treatment with an overall reduction of 5.22mm for the copper-NiTi group and 6.03mm for the tubular coaxial-NiTi group. However, the difference between the two groups was not statistically significant. Likewise, pain perception and root resorption were not significantly different between the two study groups.
CONCLUSIONS: Both copper-NiTi and tubular coaxial-NiTi archwires were equally effective in terms of teeth alignment, patients\' pain perception, and root resorption. Consideration could be given to the cost and clinician preference when selecting an initial archwire.
BACKGROUND: the trial was registered in ClinicalTrials.gov on 26/05/2022 with a registration ID: NCT05391542, https://clinicaltrials.gov/ct2/show/NCT05391542.

OBJECTIVE: A TiNb alloy wire (GUMMETAL® [GM], Toyota Central R&D Labs, Inc., Nagakute, Japan) was recently developed with unique properties for orthodontic applications. This pilot split-mouth randomized controlled trial compared maxillary canine retraction during space closure using sliding mechanics on GM vs. stainless steel (SS) archwires.
METHODS: Subjects who met the inclusion criteria were treated with fixed appliances and maxillary first-premolar extractions between September 2020 and March 2022. After leveling and aligning, maxillary archwires, fabricated by crimping together segments of 0.016×0.022\" GM and SS archwires, were placed and canine retraction initiated using nickel-titanium coil springs. Digital models of the maxillary arch were superimposed at 0, 4, 8 and 12 weeks and the amount of canine movement (mm), rate of movement (mm/month), and 3-dimensional changes (rotational, vertical extrusion, tip) were measured and compared statistically.
RESULTS: Of the 12 subjects recruited, only six completed the study with a median age of 15.8 years (12.0-17.4 years). At 12 weeks, the median canine retraction was 3.41mm (IQR: 2.10, 4.76) with GM versus 3.71mm (IQR: 1.62, 6.45) with SS. The retraction rate was 1.14mm/month (IQR: 0.69, 1.59) with GM, versus 1.24mm/month (IQR: 0.54, 2.15) with SS. The median rotational, vertical and tip changes of the canine were 7.90̊, 0.59mm and 6.15̊ with GM, and 7.25̊, 0.29mm and 2.05̊ with SS. Intergroup differences with all measurements were not statistically significant.
CONCLUSIONS: No significant differences were found between GM and SS during maxillary canine retraction. GM demonstrated clinical potential for space closure mechanics, however, future larger studies are needed.