Effects of intrusive force on selected determinants of pulp vitality.
OBJECTIVE
To determine the activity of aspartate aminotransferase (AST) in the pulp of orthodontically intruded teeth and to test the sensitivity of these teeth by means of electrical pulp testing (EPT).


METHODS
The study sample consisted of 21 healthy subjects who needed extraction of first premolars for orthodontic reasons. In every subject, one premolar included in a 0.016''- 0.022'' stainless steel spring from the first molar and loaded by the force was regarded as a test tooth. The magnitude of the intrusive tipping force for every tooth was calculated with the use of ANSYS 10.0 software. The contralateral premolar was used as a control tooth. After 7 days, the spring was removed, and EPT was applied to test and control teeth. The teeth were extracted, and the dental pulp was removed. AST activity in the pulp was determined spectrophotometrically at 20 degrees C.


RESULTS
Estimated mean AST activity values ranged from 0.572 +/- 0.097 U/mg in the test teeth to 0.348 +/- 0.053 U/mg in the control teeth (P < .01). The EPT test showed significant differences between test and control teeth (P < .001). The mean estimated magnitude of the intrusive tipping force was 61 +/- 4.5 g.


CONCLUSIONS
Seven days of orthodontic intrusion can cause metabolic changes in the pulp expressed by increased AST activity. The increased threshold in the pulp reaction to EPT indicates changes in the neural response of the pulp.
Clinic of Dental and Oral Pathology, Kaunas University of Medicine, Kaunas, Lithuania. weberis@gmail.com
Rita
R
Veberiene
Dalia
D
Smailiene
Jovita
J
Danielyte
Adolfas
A
Toleikis
Arvydas
A
Dagys
Vita
V
Machiulskiene
D000293:Adolescent; D001219:Aspartate Aminotransferases / Q000032:analysis; D001641:Bicuspid / Q000201:enzymology / Q000502:physiology; D001696:Biomechanical Phenomena; D002648:Child; D003782:Dental Pulp / Q000201:enzymology / Q000502:physiology*; D003791:Dental Pulp Test; D004558:Electric Stimulation; D006801:Humans; D016910:Orthodontic Brackets; D009969:Orthodontic Wires; D013053:Spectrophotometry; D013314:Stress, Mechanical; D014087:Tooth Movement Techniques / Q000295:instrumentation; D055815:Young Adult
D001219:Aspartate Aminotransferases