The vitality assessment of traumatised permanent anterior teeth using laser Doppler flowmetry

• Main Author: Evans, Dafydd James Parry
• Format: Dissertation
• Language: English
• Published: University of Glasgow 1995
• Subjects: Dental pulp; Dentistry

The clinical management of traumatised permanent anterior teeth is complicated by the unreliability of current methods of assessing dental pulp vitality. This study investigated the reliability of laser doppler flowmetry as a method of assessing the pulpal status of traumatised permanent anterior teeth. The study found that although laser doppler flowmetry could record pulpal blood flow, non-pulpal signals were an unavoidable component of the signal obtained. The optimum non-pulpal/pulpal flux signal ratio was obtained when the laser doppler flowmeter probe was supported by a two-stage elastomeric impression jig, perpendicular to the tooth surface, at a distance of between 2-3 mm from the gingival margin. This method resulted in only 10% of the flux signal obtained from a vital dental pulp being of non-pulpal origin. Other recording methods reported in the literature were found to have between 15-45% of the flux signal of non-pulpal origin. Flux signals from vital permanent anterior teeth were found to have two characteristics which distinguished them from flux signals originating from non-vital anterior teeth; a minimum Mean Flux value of 7 perfusion units (P.U.) and a rhythmical variation in the flux signal (termed Slow Wave Vasomotion) with a frequency of between 1-10 cycles a minute, and a mean amplitude of at least 1.6 P.U. Diagnostic criteria based on these variables were used to discriminate between flux signals from 84 vital anterior teeth and 67 non-vital anterior teeth, and were found to have a diagnostic sensitivity and specificity of 1.0. All currently used methods of assessing dental pulp vitality were found to be less reliable (have a lower sensitivity and specificity) than laser doppler flowmetry. The sensitivity and specificity of the majority of the tests remained relatively unchanged whether applied to traumatised or untraumatised teeth. The exception were tests of pulpal sensibility, which showed a large fall in specificity when applied to traumatised incisors as compared with untraumatised incisors. For example, it was found that vital luxated incisors were more likely than not to fail to respond positively to sensibility testing. Although laser doppler flowmetry was found to have a sensitivity and specificity in excess of other pulpal diagnostic tests in current use, it was also found that the pulpal status of teeth was not always determined at the time of injury but could change subsequent to the injury. Both pulpal necrosis and pulpal revascularisation were possible late consequences of dental trauma, occurring months or even years following the injury. Therefore, the reliable diagnosis of pulpal vitality provided by laser doppler flowmetry should only be regarded as an aid to treatment planning the dental care of traumatised incisors. It would appear, however, that the technique of laser doppler flowmetry has potential in increasing current knowledge regarding the pathogenesis of dental pulp disease following traumatic injury.