The effects of early orthodontic force application on pulp test responses

Abstract

The effects of orthodontic tooth movement on pulpal responses are of interest to the clinician. Alterations to pulpal physiology may result in altered responses to external stimuli. This pilot project tested a small group of orthodontic patients during the early stages of treatment. Heat, cold and electrical stimuli were applied prior to treatment, after the placement of fixed appliances and after one month of force application. A smaller group was tested after two months of force application. One month after force application there was a lack of response to electrical stimulation but there was continued response to thermal stimulation. The lack of response to electrical stimulation continued in the smaller group up to two months. The results suggest that the outcome of electric pulp testing during orthodontic treatment should be interpreted cautiously. Thermal testing will offer more reliable data.

Effects of Intrusive Force on Selected Determinants of Pulp Vitality

“…This could be explained as resulting from pressure or tension on apical nerve fibers. 19,20 As was suggested by Bender et al 18 in their study on posttraumatic teeth, no response to EPT occurs immediately after trauma caused by the concussion syndrome; however, this response normally returns over time.…”

“…This has been shown to be the most effective site of electrical testing because of its close proximity to the pulp horns. [18][19][20][26][27][28] During testing, current flow was increased slowly from the initial zero current state by adjusting the variable voltage control. Readings were recorded as the perception threshold stimulating current in microamperes.…”

“…In orthodontic patients, for whom force application might have the physiological status of the pulpal element, the response of pulp to electrical stimulation becomes inconsistent. [18][19][20] Of possible force vectors that can be applied to the teeth during orthodontic treatment, intrusion is thought to have the greatest impact on the apical region 3,[21][22][23][24] in that it may cause ''strangulation'' of the pulp by occluding the apical blood supply. 25 To date, no studies have evaluated AST activity in the dental pulp during orthodontic tooth intrusion, and no data have been generated about the response of intruded teeth to electrical pulp testing (EPT).…”

Comparison of Heat-testing Methodology

“…With hot water, a nonuniform application over a tooth could result in variable pulpal temperature changes. Heated gutta-percha use has reported temperatures from 90 C-150 C (1,9,10). Others have reported difficulty with false-negative responses because of considerable heat loss within the gutta-percha before it could be applied to a tooth (11), and normal teeth can be nonsensitive to heat, whereas other normal teeth give severely painful responses despite efforts to standardize the application of the gutta-percha (13).…”

“…Several techniques have been used in dental practice to create warming of the dental pulp to establish whether a particular tooth is sensitive to heat. The use of friction, heated gutta-percha, hot water, or a heated instrument has been previously described (1)(2)(3)(4)(5)(6)(7)(8)(9)(10)(11)(12)(13)(14)(15)(16)(17).…”