Browsing by Subject "Stainless Steel"

Now showing 1 - 5 of 5
  • Thumbnail Image
    Item
    A Frictional Evaluation of a New Surface-Modified Titanium Orthodontic Bracket
    (2000) Olsen, Marc E.; Oshida, Yoshiki; Andres, Carl J.; Katona, Thomas R.; Moore, B. Keith; Roberts, W. Eugene; Shanks, James C.
    Sliding mechanics is a popular method of moving teeth orthodontically. Sliding mechanics refers to the guiding of a tooth by means of the bracket slot along an archwire in response to some applied force. This concept of tooth movement is subject to both static and kinetic friction. An accurate evaluation of an appliance's frictional properties enables a clinician to identify applications where the utilization of a new appliance may be advantageous. The aim of this study was to evaluate the frictional properties of this new surface-modified titanium orthodontic bracket compared with a traditional stainless steel orthodontic bracket and a currently available non-surface modified titanium bracket. Fifteen brackets (5 Stainless steel, 5 Titanium, 5 Coated Titanium) were combined with five archwires from each material type (SS, NiTi, βTi). Frictional evaluation was completed on each bracket material utilizing .021" x .028" size archwire materials in a specially designed apparatus under wet conditions. The frictional resistance was measured on an Instron Universal Testing machine (Instron Corp, Canton, Mass). The brackets/archwire samples were tested one at a time individually. In addition, a single bracket/ archwire sample from each group was repeatedly tested five times. Measurements were made at every 0.1mm for 30mm via a computer attached to the testing machine. An ANOV A was used to determine differences between groups. The results indicate that stainless steel brackets exhibited significantly better static and kinetic frictional properties than the titanium brackets. Stainless steel wires possessed superior frictional properties to NiTi and β-Ti wires. NiTi wires were generally superior than β-Ti wires. As brackets and archwires were reused, the overall frictional values showed a distinct trend to increase.
  • Thumbnail Image
    Item
    A Torsional Analysis of Stainless Steel Orthodontic Wires
    (1962) Mulligan, Thomas F.
    Maximal torque and torque-twist rate were determined for straight lengths of wire. The effect of wire length on each was studied. Anti-rotational torque was determined for cuspid retraction springs, and finally, distal root torque produced by cuspid retraction springs and anterior retraction springs was determined. Torque watch gauges in combination with a Bunsen burner assembly and self-devised deflection scale were used to determine the data. Maximal torque was shown to be independent of wire length, and closely approximated the theoretically determined values, while twist was shown to be proportional to wire length. Pre-stressing followed by stress-relief produced the highest maximal torque values, while wires which received neither type of treatment exhibited the lowest values. Torque-twist rate was determined for a number of wires commonly used in orthodontics, both experimentally and theoretically. It was shown that anti-rotational torque produced by cuspid retraction springs used in the Segmented Arch Technique was not only capable of preventing cuspid rotation during distal tooth movement, but could actually move the distal of the cuspid labially on the basis of theoretical mechanics. Initial activation of anterior retraction springs used in the Segmented Arch Technique produces added distal root torque for the appliance when activated for distal tooth movement, while it appears that both cuspid and anterior retraction springs produce sufficient distal root torque to prevent forward root displacement.
  • Thumbnail Image
    Item
    Comparison of Electrosurgical and Formocresol Pulpotomy Procedures
    (1997) Fulkerson, Bradley Todd; Dean, Jeffrey A.; Avery, David R.; Sanders, Brian J.; Zunt, Susan L.; Legan, Joseph E.
    Formocresol is the most commonly used pharmacologic pulpotomy agent. Concerns over its safety have led investigators to search for new pulpotomy medicaments. This study compared the electrosurgical pulpotomy with the formocresol pulpotomy in teeth requiring pulp therapy after carious involvement. There were 25 pulpotomies performed in each group. The teeth were evaluated for clinical and radiographic success after at least six months. In the electrosurgical group, the clinical and radiographic success rates were 96 percent and 84 percent, respectively. The age range at the time of treatment was 26 to 97 months, with a mean treatment age of 63.6 months. The postoperative observation time range was six to 31 months, with the mean being 10.9 months. In the formocresol group, the clinical and radiographic success rates were 100 percent and 92 percent, respectively. The age range at the time of treatment was 32 to 126 months, with a mean treatment age of 68.2 months. The postoperative observation time ranged from five to 25 months, with the mean being 11.5 months. The electrosurgical and formocresol groups were compared for differences in the percentage of successes by using a Fisher's Exact test. There were no statistical differences between the two groups at the p < 0.05 level. Therefore, this study failed to demonstrate a statistically significant difference in the success rate between the electrosurgical and formocresol pulpotomy techniques and supports the use of the electrosurgical pulpotomy as a viable and safe alternative to formocresol.
  • Thumbnail Image
    Item
    A Comparison of Frictional Forces During Simulated Cuspid Retraction on a Continuous Edgewise Archwire
    (1982) Allai, W. Wesley; Garner, LaForrest D.; Sondhi, Anoop; Shanks, James C.; Swartz, Marjorie L.; Barton, Paul
    This investigation was designed to compare the force (grams) required to overcome a simulated cuspid retraction assembly capable of three dimensional control during the retraction process. It was hypothesized that a significant difference in the mean retraction values exists between the newer orthodontic alloys of Nitinol, Beta-Titanium, as well as Stainless Steel. One hundred eighty bracket and archwire combinations were examined as follows: Sample # Wire Cross-section Wire Material 30 .016”x.022” Stainless Steel 30 .017”x.025” ” 30 .016”x.022” Nitinol 30 .017”x.025” ” 30 .016”x.022 Beta-Titanium (TMA) 30 .017”x.025” ” A statistically significant difference was shown to exist between all six groups examined regarding the variables of wire size and wire material. The statistical analysis revealed that increasing rectangular archwire cross-sectional size from .016"x.022" to .017"x.025” rectangular wire when simulating canine retraction using an .018" slotted Lewis bracket will lead to significantly greater functional forces. The analysis of wire materials indicated that a significant difference (p=.01) exists between rectangular Beta-Titanium (TMA), Nitinol, and stainless steel during simulated cuspid retraction utilizing a narrow .018" Lewis bracket ligated with A-lastik ligatures. The least frictional force was observed with the .016"x.022" stainless steel test cells. The largest frictional force was found in the .017”'x.025" Beta-Titanium retraction specimens. Nitinol revealed force data intermediate between stainless steel and Beta-Titanium. The maximum resistance assembly developed 2.3 times the minimum frictional force observed. The mean grams of frictional force within these test cells ranged from 55.03 grams for the .016"x.022" retraction assembly to 132.68 grams for the .017"x.025" Beta-Titanium assembly. A topographical scanning electron microscope survey of the brackets and archwires utilized was included to provide qualitative insights into the quantitative results described.
  • Thumbnail Image
    Item
    Laser-treated stainless steel mini-screw implants: 3D surface roughness, bone-implant contact, and fracture resistance analysis
    (Oxford University Press, 2016-04) Kang, He-Kyong; Chu, Tien-Min; Dechow, Paul; Stewart, Kelton; Kyung, Hee-Moon; Liu, Sean Shih-Yao; Department of Orthodontics and Oral Facial Genetics, School of Dentistry
    BACKGROUND/OBJECTIVES: This study investigated the biomechanical properties and bone-implant intersurface response of machined and laser surface-treated stainless steel (SS) mini-screw implants (MSIs). MATERIAL AND METHODS: Forty-eight 1.3mm in diameter and 6mm long SS MSIs were divided into two groups. The control (machined surface) group received no surface treatment; the laser-treated group received Nd-YAG laser surface treatment. Half in each group was used for examining surface roughness (Sa and Sq), surface texture, and facture resistance. The remaining MSIs were placed in the maxilla of six skeletally mature male beagle dogs in a randomized split-mouth design. A pair with the same surface treatment was placed on the same side and immediately loaded with 200 g nickel-titanium coil springs for 8 weeks. After killing, the bone-implant contact (BIC) for each MSI was calculated using micro computed tomography. Analysis of variance model and two-sample t test were used for statistical analysis with a significance level of P <0.05. RESULTS: The mean values of Sa and Sq were significantly higher in the laser-treated group compared with the machined group (P <0.05). There were no significant differences in fracture resistance and BIC between the two groups. LIMITATION: animal study CONCLUSIONS/IMPLICATIONS: Laser treatment increased surface roughness without compromising fracture resistance. Despite increasing surface roughness, laser treatment did not improve BIC. Overall, it appears that medical grade SS has the potential to be substituted for titanium alloy MSIs.