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Biomedical subjects

G F Andreasen

Publications and source records attributed to G F Andreasen.

At least 19 recordsLinked to original sources
PubMed1989

Bond strength comparison: a simplified indirect technique versus direct placement of brackets.

Two methods for orthodontic bonding were used to attach brackets to 48 incisor and 48 premolar extracted human teeth. Half of the sample teeth were bonded by means of a highly filled bis-GMA adhesive by a direct placement method. The remaining teeth were bonded with the same adhesive by an indirect method suggested by Thomas. Actual chairside bonding procedures were simulated with regard to the timing and manipulation of adhesives and attachments. Tensile and shear bond strengths are reported for each of the two methods of bracket attachment.

Bisphenol A-Glycidyl Methacrylate↗
PubMed1989

Aligning, leveling, and torque control--a pilot study.

Aligning, leveling, and anterior torque control of teeth from the onset of treatment is suggested with thermal ni-ti rectangular low stiffness wires. Before and after superimpositions show the degree that torque control was achieved on four clinical patients.

Adolescent↗
PubMed1988

Thermomechanical study of Ni-Ti alloys.

A preliminary study was conducted to demonstrate the usefulness of the combined technique of differential scanning calorimetry (DSC) and mechanical testing for the shape memory metals of 54NiTi and 53NiTiCo(3%) alloys. The DSC technique was used to measure precise transformation temperatures and the amount of thermal energy required for the corresponding phase transformation. The degree of plastic deformation by bending and the effect of alloying (such as Co) were studied with combined DSC and mechanical property measurements.

Alloys↗
PubMed1988

Bonding and debonding brackets to porcelain and gold.

Today's orthodontic practice includes a larger proportion of adults. Because many of these adults have crown and bridge restorations fabricated from porcelain or gold, the orthodontist must use methods that permit the attachment of orthodontic brackets to porcelain and nonprecious metal or gold. A bracket may be placed on single-unit crowns of porcelain or gold, but banding becomes difficult. Thus bonding the orthodontic bracket to the restoration provides a satisfactory alternative. This clinical report describes several techniques for bonding orthodontic brackets to porcelain or gold surfaces, and some suggestions for removal of bonded brackets.

Chemical Phenomena↗
PubMed1979

55 Nitinol wire: force developed as a function of "elastic memory".

Closing spaces is done either by translation of the edgewise brackets over an archwire or by the use of closing loops of some common design. This investigation suggests the concept of the further refinement of the "wire rubber band" as a means of closing spaces. Advantages of such a wire hypothetically would be to level the dentition, align the dentition, and condense spaces in the dentition with only one or two stretched nickel titanium wires having the proper temperature transition range (TTR). The temperature of the mouth would make such wires return to their original prestretched length. A correctly-sized wire would have sufficient stiffness at mouth temperature, and it would be kept at or above its TTR. The system eliminates friction from edgewise bracket translation and also the use of many auxiliary closing devices as well as reducing the number of archwire changes, thus saving chairside time.

Dental Alloys↗