Biomedical subjects

Josef W Freudenthaler

Publications and source records attributed to Josef W Freudenthaler.

3 recordsLinked to original sources

PubMed2006

Heat generated by residual adhesive removal after debonding of brackets.

AIM: To measure the rise in temperature during mechanical removal of residual adhesive after debonding of brackets in vitro. METHODS: Different carbide burs on a high-speed handpiece were tested. Acrylic on the buccal surfaces of recently extracted human maxillary incisors was removed using 3 types of carbide burs (6-, 12-, 40-fluted) with a varying number of windings relative to the long axis of the shaft. The temperature was measured using a thermocouple probe in the pulp chamber of the extracted teeth. RESULTS: The highest mean rise in temperature was measured using a 6-fluted bur (+9.4 degrees C, P < .001), followed by the 12-fluted bur (+6.5 degrees C, P <.001). The lowest rise in temperature (+1.2 degrees C, not significant) was seen with a 40-fluted bur. After 3 to 8 seconds of continuous grinding, the rise in temperature seems to slow down. CONCLUSION: The removal of residual adhesive after debonding is best performed with fine burs. If 6-fluted burs are used, a pause after 5 to 10 seconds of continuous grinding is recommended, especially in the mandibular anterior area.

Body Temperature↗

PubMed2003

A cephalometric comparison of skulls from different time periods--the Bronze Age, the 19th century and the present.

The aim of this study was to evaluate secular trends by means of orthodontic measurements on lateral cephalograms. We use roentgenograms from three populations: 22 Bronze Age skulls from a cemetery near Hainburg/Austria, 140 soldiers who served in the Hapsburg Imperial Army in the late 19th century, and 154 contemporary recruits of the Austrian Federal Army. Using conventional morphometric analysis, no statistically significant differences could be established. But applying geometric morphometrics to the 2D-coordinates of the pentagon composed of the landmarks Sella, Nasion, Articulare, Gonion and Menton, some biologically interpretable differences were detected, the size allometry between the 19th- and 20th-century populations being the only notable one. We conclude that landmarks should be digitized directly (and many more of them) and that conventional methods used in clinical orthodontics are inappropriate for addressing the scientific questions approached here.

Anthropology, Physical↗

PubMed2002

Rectangular loops in inconsistent force systems: a laboratory investigation.

MATERIAL AND METHOD: [corrected] The force system delivered by the rectangular loop (R-loop) was the subject of this in-vitro investigation. The correction of a first-order irregularity was simulated in an inconsistent force system. Three types of R-loop made of 0.017" x 0.025" TMA wire but differing in length and insertion system were tested in a 3D strain gauge (Hottinger, Darmstadt, Germany). The buccal segment consisted of one molar and two bicuspids, with the first bicuspid as an active unit scheduled to be moved buccally into the dental arch. RESULTS: The first R-loop tested revealed too high a force magnitude to be recommended for clinical use. A loop connecting only two teeth and bypassing the second premolar delivered a favorable initial force of 85 cN with a drop of 20 cN per 1 mm deactivation. In order to achieve a translatory tooth movement, a buccal root torque must be bent in addition into the short horizontal leg of the R-loop. The use of a transpalatal arch is indispensable if adverse side effects are to be avoided.

Biomechanical Phenomena↗