A Characteristic Analysis of the Pulse Transit Time to Dental Pulp : An Attempt at a New Approach to Dental Pulp Diagnoses Based on the Microcirculatory System

Objectives: This study examined the characteristics of healthy teeth by analyzing the pulse transit time (PTT) and factors influencing the PTT of teeth to diagnose dental pulp using transmitted-light plethysmography (TLP).
Design: The PTT was measured in 58 healthy maxillary central incisors in 34 healthy subjects. The PTT values in earlobes (ears), fingertips, and toes were also measured for comparison purposes. In addition, the optical density of the teeth was measured. Data were analyzed using a one-way analysis of variance followed by Dunnettʼs test. Pearsonʼs correlation was performed to determine the relationship between the tooth PTT and mean blood pressure, systolic blood pressure, diastolic blood pressure, and heart rate.
Results: The average PTT of toes was significantly longer than the other three measurement sites, including the teeth. Additionally, the toes had a significantly longer average PTT among subjects in their 20s than in other age groups. There were no significant differences in the average PTT by age at the measurement sites of the teeth, ears, and fingertips, but the average PTT for the teeth and ears tended to decrease with age. The PTT of the teeth negatively correlated with the heart rate and tended to decrease with an increasing heart rate. Furthermore, the PTT of the teeth in females was significantly longer than in males.
Discussion: The average PTT of the toes was significantly longer than that at other measurement sites, possibly due to the distance from the measurement site to the heart. The average PTT of teeth tended to decrease with age, but there were no significant differences by age. The decrease in the pre-ejection period (PEP) with an increasing heart rate might have been due to the decrease in the PTT with an increasing heart rate. The loss of vascular elasticity caused by progressive atherosclerosis increases the pulse wave velocity (PWV) and decreases the PTT of teeth. Finally, the gender difference in the average PTT of teeth might have been due to the blood pressure and presence of female hormones.
Conclusion: We found that the PTT of teeth was influenced by the heart rate and elasticity of the systemic blood vessels. The PTT is useful for evaluating the blood flow in teeth and is promising for future applications in the diagnosis of dental pulp, such as in cases of chronic caries and trauma to teeth.