Orthodontics and Orthodontology Commons^™

A Comparison Of Enamel Detachments After Debonding Between Unitek's "Dynalok" Bracket And A Foil-Mesh Bracket: A Scanning Electron Microscope Study, Robert E. Meister

Loma Linda University Electronic Theses, Dissertations & Projects

The intent of this paper was to: 1. Evaluate the mode of adhesive failure when debonding both flexible and rigid base orthodontic brackets. 2. Evaluate the bracket bases for enamel detachments. 3. Measure the enamel detachments.

After preforming shear test on flexible and rigid base orthodontic brackets mounted to extracted human teeth it was determined that failure occurred at the enamel/adhesive interface 30% of the time, at the bracket/adhesive interface 10% of the time and a combination of these 60% of the time for both groups.

Five brackets from each group were evaluated for enamel detachments using energy dispersive x-ray …

An Evaluation Of 17-4 Precipitation-Hardenable Stainless Steel Alloy For Use As An Orthodontic Wire, Martin G. Martz

Loma Linda University Electronic Theses, Dissertations & Projects

17-4 precipitation-hardenable stainless steel, a high strength alloy developed for aircraft applications, has been examined for possible use in orthodontics. The effects of solution treatment, various refrigeration treatments, and various aging treatments on standard tensile properties were measured. Comparisons were made with the tensile properties of 18-8 stainless steel and a Co-Cr alloy presently used in orthodontics.

Solution treatment was found to decrease ultimate strength by 37.8%, 0.2% yield strength by 45.9%, and (YS)/E ratio by 36.7%, while having almost no effect on elastic modulus or percentage elongation. Refrigeration treatments had statistically significant but small effects on tensile properties. Aging …

A Comparison Of Two Rapid Palatal Expansion Appliances And Their Effect On Palatal Cross-Sectional Area, William D. Scott

Loma Linda University Electronic Theses, Dissertations & Projects

Two rapid palatal expansion appliances, acrylic-free and acrylic-reinforced, were compared for their effect on the cross-sectional area of the palate. Two groups, twenty-five patients in each, were selected so that they would match as closely as possible with regards to age and sex distribution. The pre-treatment and post-treatment maxillary models were duplicated, and this duplicate model was then trimmed in a specific manner to allow the cross-sectional area between the first permanent molars to be compared. The results indicate that there is no difference, at the five percent level of significance, between these two appliances. It is concluded that the …

Force Loss In Retraction Springs At 37°C As Affected By Time, Roger Edward Clawson

Loma Linda University Electronic Theses, Dissertations & Projects

Closed helix retraction springs fabricated from .016 X .016 inch Blue Elgiloy, Permachrome Standard stain less steel, and Multiphase orthodontic wire were tested at 37°C in their heat and nonheat treated condition to determine force relaxation properties. Electronic equipment consisting of load cells, regulated power supply, and an automatic recording device were used to measure force changes which occurred in the wire samples over a seven day period. A constant temperature was maintained by an ethylene glycol and water circulator. A temperature probe and an electronic thermometer monitored the 37°C water bath surrounding the wire samples. The data was graphed …

A Comparative Study Of Tensile Properties In Five Orthodontic Wires, Charles B. Mcdermott

Loma Linda University Electronic Theses, Dissertations & Projects

The tensile properties of .017 x .025" stainless steel. Multiphase, Blue Elgiloy, beta titanium, and Nitinol were tested and compared. All wires were tested in the "as received" condition. Fifteen samples of each type of wire were tested in order to determine the (1) modulus of elasticity, (2) .2% yield strength, (3) ultimate tensile strength, (4) percentage elongation and (5) maximum elastic deflection.

The modulus of elasticity and .2% yield strength are the most important properties to orthodontists because of their influence on the wire's stiffness, strength and range. The ratio of yield strength/modulus of elasticity, termed maximum elastic deflection, …

Methodology In Measurement Of Load Loss Or Gain In Orthodontic Wires : A Pilot Study, Merton S. Lacy

Loma Linda University Electronic Theses, Dissertations & Projects

The purpose of this investigation was to develop methods and equipment to measure and record over any desired length of time the loss or gain in force of any material used in orthodontics that can produce a force upon an object. The material and the object being acted upon should not be disturbed while measuring that force.

Holding devices were designed and constructed in two basic forms. For intrusive and extrusive type forces, a load cell was fixed horizontally in such a position that an adjustable tube with a set screw to hold the wire could be rotated to cause …

Fatigue Properties Of Orthodontic Wire, Kirkland B. Reuer

Loma Linda University Electronic Theses, Dissertations & Projects

Fracture of orthodontic appliances can be a problem because of the time involved to replace and repair them. It has been shown that most failures have been a result of fatigue fracture, i.e., failure resulting from cyclic loading.

The purpose of this study was to determine what effect variation of the type of orthodontic wire and heat treatment had on fatigue resistance. A device was constructed to put a cyclic load on a piece of wire until fracture. Two types of cobalt-chromium alloy wire (Blue and Green Elgiloy from Rocky Mountain Orthodontics) and three types of stain less steel wire …

Effects Of Heat Treatment On The Mechanical Properties Of Chromium-Cobalt Alloy Wire, Robert L. Nations

Loma Linda University Electronic Theses, Dissertations & Projects

Since virtually all stages of orthodontic treatment involve forces obtained from deformed metallic materials, an understanding of properties of metals is an important part of orthodontics. The use of chromium-cobalt alloy for arch wires is relatively new to the field, and more needs to be known about its use in order to get the most from this product.

Many clinicians feel that advantages can be gained through a low temperature heat-treatment to change certain mechanical properties of the material. A tensile test was chosen in the attempt to learn more about this alloy in the untreated form as well as …

A Clinical Method For Predicting Orthodontic Band Sizes, Robert P. Mohr

Loma Linda University Electronic Theses, Dissertations & Projects

A correlation was established among the orthodontic band sizes in a given individual. The original sample contained 258 data sets (Unitek Corp. band sizes from first molar through the first molar in both arches) which were computer analyzed. The maxillary right central incisor band size was selected as the "predictor size" for a band size prediction table developed from this study.

An additional 56 data sets were tabulated and became the test sample to test the accuracy of the band size prediction table. Band sizes of the test sample were predicted within ±1 band size 66% of the time and …

Tensile Properties Of Stainless Steel Orthodontic Wire, Elbert E. Jackson

Loma Linda University Electronic Theses, Dissertations & Projects

Ten types of .020 inch stainless steel wire were compared using a tensile test. The wires were tested in the as-received condition and after heat treatment at 750°F for eleven minutes. The data were then analyzed statistically using the general linear hypothesis.

In the as-received condition each of four mechanical properties--elastic modulus, 0.2 per cent yield strength, tensile strength, and percent elongation--was found to vary significantly from one type to another.

When subjected to heat treatment, the elastic modulus proved to be the most stable of the four properties, changing only slightly in three cases. There was no significant change …

An Evaluation Of A Precipitation Hardened Stainless Steel Alloy As An Alternate To Chrome Cobalt Alloys For Orthodontic Purposes, Joseph M. Caruso

Loma Linda University Electronic Theses, Dissertations & Projects

The intent of this paper was to evaluate a precipitation hardenable stainless steel (Alloy I) as an alternate to chromium cobalt alloys (Alloy II) for orthodontic purposes.

After evaluating several heat treatments of alloy I it was determined that solution treatment produced a wire that was soft initially and had similar properties found with alloy II. After solution treatment of alloy I a 330 gram load was required to deform the wire 1.0 mm which proved to be similar to the 295 gram force required for alloy II for the same deformation and only an 11% increase in resistance of …

Heat Treatment Of Chrome Cobalt Alloy Orthodontic Wire, Galen M. Fillmore

Loma Linda University Electronic Theses, Dissertations & Projects

Chrome cobalt alloy orthodontic wire may be heat treated to increase spring performance and efficiency. This study was designed to quantify the effects that several heat treatment temperatures have upon the ability of .016" x .022" type 1 chrome cobalt wire to resist permanent deformation. In addition, the changes in resistance to permanent deformation due to heat treatment at 900° F were studied in .018" stainless steel wire and chrome cobalt wire of all four tempers.

When compared to untreated wire, .016" x .022" type 1 chrome cobalt wire exhibited a maximum increase of approximately 174 percent in resistance to …

The Theoretical Distribution Of Forces In The Rigid Component Of The Buccal Arch Positioner, Dennis H. Teruya

Loma Linda University Electronic Theses, Dissertations & Projects

The distribution of an applied force to the rigid component of the Buccal Arch Positioner was determined with a theoretically formulated model. The rigid component was assumed to be a free body without the semi-rigid attachments and was evaluated at four points for the force distribution. The summation of the forces and the moments were equated to zero and were utilized to derive equations to solve for the unknown forces. The unknown forces at each point of the rigid component were solved for in terms of the given force applications.

A laterally directed force application at one of the posterior …

The Development Of A New Appliance For The Third Stage Of Begg Treatment, Ronald C. Parker

Loma Linda University Electronic Theses, Dissertations & Projects

The third stage of Begg treatment can pose difficulties to the orthodontist. Some of the undesirable developments encountered are anchorage loss, unintentional tooth tipping, extrusion, intrusion, palatal and mandibular rotation, muscular strain and profile deficiency or procumbency. In the interest of eliminating or minimizing these developments a new appliance was developed for use during the third stage of treatment.

Simply described, the appliance consisted of a rigid vestibular arch that provided anchorage for flexible extensions to each tooth. Extraoral force was directed to the maxillary rigid arch to counter anterior root torquing forces.

Anchorage control, maxillary incisor torquing efficiency and …

A Clinical Evaluation Of A Technique Utilizing Plastic Modules For Cuspid And Incisor Retraction, Dwane I. Johnston

Loma Linda University Electronic Theses, Dissertations & Projects

In a clinical study, polyurethane-type plastic modules were evaluated for use in retracting cuspids and incisors in Class I extraction cases.

Seven patients were selected to be treated with a technique utilizing these plastic modules. All cases were in Class I molar relationship and were either bimaxillary, protrusive or had tooth-size, arch-length discrepancies.

Evaluation was based on rate of cuspid and incisor retraction and the control of molar anchorage during the retraction phase.

At four-week intervals data were collected on space closure. At the same time, such subjective data as amount and duration of pain, difficulty of appliance adjustment and …