Comparison of stainless steel and titanium-molybdenum alloy closing loop archwires using numeric simulation model based on finite element method.

INTRODUCTION: The objective of this study was to determine and compare the moment-to-force (Mc/F) ratio and the type of tooth movement generated in the anterior and posterior segments in orthodontic space closure with stainless steel and titanium-molybdenum alloy loop archwires. METHODS: Three-dimensional model of the maxilla from which the first premolar was extracted, 18 × 25-mil slot stainless steel brackets, and 16 × 22-mil stainless steel and ß titanium-molybdenum alloy (TMA) closing loop archwires with anterior gable bend of 15° and posterior gable bend of 25° were constructed. The archwires were engaged in the brackets, and 1-mm activations were carried out, which were repeated 5 times. The anterior and posterior segment Mc/F ratio and the type of tooth movement generated by the 2 wires were compared. RESULTS: It was found that the Mc/F ratio for the anterior segment was approximately 5 mm, and for posterior teeth was approximately 10 mm for both stainless steel and TMA closing loop archwire. The anterior teeth exhibited controlled tipping, whereas the posterior teeth showed bodily tooth movement, which was in accordance with the Mc/F ratio that was obtained. CONCLUSIONS: The Mc/F ratio and the type of tooth movement exhibited by stainless steel and TMA closing loop archwires were similar in both anterior and posterior segments.

An In Vivo Randomized Clinical Evaluation of the Surface Morphology of Nickel-Titanium, Beta-titanium, and Copper-Nickel-Titanium.

AIM: Variation in the surface roughness of archwires not only leads to more accumulation of plaque but also modifies the coefficient of friction. This necessitated for the present study to evaluate the surface characteristics of 0.016 × 0.022-inch nickel-titanium, beta-titanium, and copper-nickel-titanium archwires, before and after their use in the oral cavity using atomic force microscopy. MATERIALS AND METHODS: The control and experimental samples were measured at three different positions under atomic force microscopy. The surface roughness was measured using roughness average, root mean square, and maximum height before and after use in the oral cavity among 60 adult participants. Data were analyzed using a one-way analysis of variance and Student's t tests using the Statistical Package for Social Software (SPSS) v.20.0. RESULTS: The surface roughness of archwires increased considerably after their clinical use compared to controls for nickel-titanium (p = 0.013) and beta-titanium (p = 0.002). A similar trend was noticed for root mean square where nickel-titanium (p = 0.014) and beta-titanium (p = 0.013) had increased root mean square. Maximum height was also noticed in nickel-titanium (p = 0.031) and beta-titanium (p = 0.016). CONCLUSION: Surface roughness and the level of friction of the orthodontic wires increase significantly for nickel-titanium and beta-titanium after the clinical use. There is a difference in increase of surface roughness of the archwire within and between the bracket slots. CLINICAL SIGNIFICANCE: Nickel-titanium and beta-titanium wires show more roughness and resultant higher friction levels after use in the oral cavity. Hence, care related to plaque accumulation is essential.

Comparative cephalometric evaluation of tongue position in subjects with skeletal class II division 1 and division 2 malocclusion.

AIM AND OBJECTIVE: To evaluate and compare the position of the tongue from rest to centric occlusion in subjects with skeletal class II division 1 and skeletal class II division 2 malocclusions with subjects of skeletal class II normal occlusion. MATERIAL AND METHODS: The study was conducted on 30 individuals equally divided into three groups of skeletal class II division (div) 1, skeletal class II div 2, and skeletal class I normal occlusion. The study was conducted on two lateral cephalograms for each subject: one taken at rest and one in centric occlusion. RESULTS: On evaluation of tongue posture, a statistically significant difference was observed at the middle portion of the tongue in class II div 1 malocclusion, and at the posteromedial portion of the dorsum of the tongue in class II div 2 skeletal malocclusions as the tongue moved from rest to centric occlusion. While statistically significant differences were found between class II div 2 malocclusion and class I normal occlusion, no statistically significant differences were observed between class II div 1 and class II div 2 malocclusions. CONCLUSION: Tongue position was observed to be the same in both class II div 1 and class II div 2 malocclusions, with no statistically significant differences. However, a great change was seen in the tongue position from rest to centric occlusion.

Matrix Metalloproteinase-8 Levels in Peri-Miniscrew Crevicular Fluid During Immediate and Delayed Orthodontic Loading--A Split-Mouth Study.

Purpose: To compare the matrix metalloproteinase-8 (MMP-8) levels in the peri-miniscrew implant crevicular fluid (PMCF) of immediate-loaded and delayed-loaded miniscrew implants at different time intervals. Materials and Methods: Titanium orthodontic miniscrews were placed bilaterally in the attached gingiva of 15 patients between the maxillary second premolar and maxillary first molar for en masse retraction. This split-mouth study was designed to have an immediate-loaded miniscrew on one side and a delayed-loaded miniscrew on the other side that was loaded 8 days after miniscrew placement. PMCF was collected from the mesiobuccal aspects of the immediate-loaded implants at 24 hours, 8 days, and 28 days after loading, and from the delayed-loaded miniscrew implants at 24 hours and 8 days before loading and 24 hours and 28 days after loading. An enzyme-linked immunosorbent assay kit was used to assess MMP-8 levels in the PMCF samples. Unpaired t test, ANOVA F-test, and Tukey post hoc test were used to evaluate data at the P < .05 level. Results: Although there were slight alterations in the MMP-8 levels in the PMCF over time, there was no statistically significant difference in the MMP-8 levels between groups. There was a statistically significant decrease in the levels of MMP-8 between 24 hours after miniscrew placement and 28 days after loading on the delayed-loaded side (P < .05). Conclusion: The MMP-8 levels did not vary much between immediate-loaded and delayed-loaded miniscrew implants as a result of the force application. However, there was no significant difference between immediate loading and delayed loading in terms of biologic response to mechanical stress. The increase in MMP-8 levels after 24 hours post-miniscrew insertion, as well as the subsequent gradual reduction over the course of the study period in both immediate and delayed groups after loading, is probably due to the bone adapting to stimuli.

Treatment effects of "PowerScope" fixed functional appliance - a clinical study.

AIM: To study the skeletal, dental effects and evaluate the soft tissue changes with PowerScope-fixed functional appliance in class II malocclusion. MATERIALS AND METHODS: This clinical study was carried out where a total of 10 growing (CVMS 3 and 4) Class II Division 1 malocclusion patients, indicated for treatment with fixed functional appliance were allocated based on specific inclusion criteria. PowerScope (American Orthodontics) was used as the fixed functional appliance. Skeletal, dental and soft tissue effects of the appliance with various angular and linear parameters on a digital lateral cephalogram were evaluated for all 10 participants. Records were collected before the insertion of PowerScope appliance (T0) and after 5 months, during the appliance removal (T1). All participants were treated with 0.018"×0.025" MBT (3M Unitek) prescription. Statistical analysis was performed using a paired t-test to compare individual mean changes for each treatment category. RESULTS: Statistically significant changes were seen in skeletal parameters such as forward positioning of the mandible with an increase in SNB angle and N perpendicular-Pogonion distance, the class II jaw base relationship improved with reduction in ANB angle and Wits appraisal. Significant changes were observed in dental parameters such as forward positioning of mandibular incisors, maxillary molar distalization and intrusion with reduction in overbite and overjet respectively. In the soft tissue, a significant improvement in facial profile was seen due to an increase in labiomental angle. CONCLUSIONS: The results of this study have shown that statistically significant changes in skeletal, dental and soft tissue parameters.

Comparative evaluation of interrupted and intermittent forces on canine retraction: an in vivo study.

INTRODUCTION: Various force systems are used in orthodontics to move teeth, such as continuous, intermittent and interrupted. Teeth responds differently to these orthodontic forces. AIMS: The aim of the study is to compare the rate of canine retraction with intermittent and interrupted forces. MATERIALS AND METHODS: A split mouth study was carried among eighteen participants. One side of maxillary arch randomly received interrupted force with elastomeric powerchain while other received intermittent force with elastics with magnitude of 150-170g for canine retraction on each side. For 15 weeks, participants were asked to wear the elastics 8 hours a day whereas the elastomeric powerchains were replaced by operator every 5 weeks. The outcomes were assessed using scanned images of study models collected at the beginning (T0) and 15 weeks later (T3) as well on OPG. Linear and angular measurements were used to measure the distal movement, rotation as well tipping of canines and the results were statistically analysed using Independent t-test. RESULTS: The distal movement of canine on the interrupted force side was 0.98mm/5weeks and on the intermittent force side was 1.06mm/5weeks. The distopalatal rotation on interrupted and intermittent force side was 8.38° and 5.72°. Tipping measured on OPG was 5.72° and 5.27° for interrupted and intermittent force. No statistically significant differences were found. CONCLUSION: The rate of canine retraction with interrupted force and intermittent force showed no statistically significant differences. Less canine rotation and tipping with intermittent force compared to interrupted force though not statistically significant.

Comparison of Volumetric Dimensions of Pharyngeal Airway for Different Dentofacial Skeletal Patterns Using Cone Beam Computed Tomography.

INTRODUCTION: After a century of controversies, we are still not certain on the relationship between airway volume and facial morphology. OBJECTIVE: To measure nasopharyngeal airway volume and compare it among different skeletal patterns. MATERIALS AND METHODS: Forty five CBCT scans of patients between sixteen to twenty five years were used in the study. The nasopharyngeal airway was divided into upper, middle and lower segments. CBCT images were grouped into skeletal class I, class II and class III. RESULTS: There was highly significant difference in upper (p=0.001) and middle pharyngeal airway volume (p<0.001) among 3 skeletal groups. Lower pharyngeal airway volume was also statistically significant (p=0.051) among 3 groups. Total pharyngeal airway volume did not show any significant correlation. CONCLUSION: Nasopharyngeal airway volume seems to play a role in different skeletal patterns.

Bone-Miniscrew Contact and Surface Element Deposition on Orthodontic Miniscrews After Ultraviolet Photofunctionalization.

PURPOSE: The aim of this study was to evaluate the effect of ultraviolet (UV) photofunctionalization on peri-implant osteogenesis of miniscrews. MATERIALS AND METHODS: Titanium orthodontic miniscrews were placed in the maxillary premolar-molar region of 17 patients undergoing fixed orthodontic treatment. This was a split-mouth study wherein the miniscrews on one side were treated with UV photofunctionalization and those on the other side were left untreated. Photofunctionalization was performed by placing the miniscrews in a chamber consisting of UV-A and UV-C lights for 15 minutes immediately prior to implantation. Efficacy of the UV chamber was assessed by examining stereomicroscopic images of a 10-µL droplet of double-distilled water placed on a UV-treated titanium pellet. Retrieved miniscrews were evaluated for bone-miniscrew contact (BMSC) using scanning electron microscopy (SEM) based on a custom-devised 4-point objective scoring system. Surface element deposition of miniscrews was estimated using energy-dispersive x-ray spectrometry (EDX). Ratios of Ca/Ti and Ca/P were calculated for upper, middle, and lower regions of all miniscrews. RESULTS: Increased spread of the water droplet over the UV-treated pellet showed that photofunctionalization converted the titanium surface from hydrophobic to superhydrophilic. SEM imaging revealed that BMSC was greater in the photofunctionalized group, but only in the lower third of miniscrews, and this was not statistically significant. EDX analysis revealed that Ca/Ti and Ca/P ratios in both groups were similar. Thus, there was no significant difference between peri-implant osteogenesis of UV-treated and untreated miniscrews. CONCLUSION: These results suggest that UV photofunctionalization did not enhance the biologic potential of titanium orthodontic miniscrews in clinical application.

A comparison of tensile weld strength and microstructural changes in four arch wires, before and after immersion in 1.23% acidulated phosphate fluoride solution: an in-vitro study.

OBJECTIVES: The objective of this study is to evaluate and to compare the tensile weld strengths and microstructural changes in four archwires namely beta titanium, stainless steel (SS), blue elgiloy and timolium before and after immersion in 1.23% acidulated phosphate fluoride (APF) solution. MATERIALS AND METHODS: The mean tensile weld strength of a weld joint of four arch wires were compared pre-fluoride (Group 1) with post fluoride (Group 2) and the microstructural characteristics of weld joints were evaluated under an optical microscope. RESULTS: The mean tensile weld strength for beta titanium was 445.64 N/mm 2, blue elgiloy was 363.26 N/mm 2, SS was 358.30 N/mm 2 and timolium was 308.62 N/mm 2. After immersion in fluoride the mean tensile strength for beta titanium was 427.16 N/mm 2, blue elgiloy was 359.86 N/mm 2, SS is 349.44 N/mm 2 and timolium is 294.86 N/mm 2. After immersion in fluoride, the beta titanium and SS had a smooth fusion at the center of weld assembly with characteristic nugget formation. The beta titanium weld assembly had greater tensile weld strength than other welded assemblies. Blue elgiloy ranked second, whereas SS and timolium were third and fourth respectively. CONCLUSION: The wires in descending order of their mean tensile weld strength, on evaluation of their weld joints were found to be: Beta titanium > blue elgiloy > SS > timolium. The reduction in tensile weld strength was statistically insignificant for all the archwires after exposure to 1.23% APF at 37°C for 90 min.