Evaluation of Sensibility Threshold of Dental Pulp to Electric Pulp Test (EPT) in the Teeth under Fixed Orthodontic Treatment with 0.014 and 0.012 Initial NiTi Archwire ZC16-ZC19
Dr. Nazanin Shahsavand,
Resident, Department of Endodontics, School of Dentistry, Hamadan University of Medical Sciences, Hamadan, Iran.
Introduction: The health and integrity of the dental pulp following orthodontic therapy is of major importance for tooth survival. EPT is a conventional method for evaluation of pulp vitality.
Aim: The aim of the study was to evaluate sensibility of the dental pulp to EPT in the teeth under fixed orthodontic treatment with 0.014 and 0.012 initial NiTi archwire.
Materials and Methods: In this study, 516 teeth (maxillary central and lateral incisors) were studied prospectively in 129 patients assigned to three groups: the 0.012 NiTi archwire, the 0.014 NiTi archwire and the control group. The aligning forces were administered using initial NiTi archwires of 0.012 and 0.014 ligated on fixed appliances by using the MBT straight wire technique. Stimulation of electrical sensibility threshold was done by EPT and was measured pre-bonding (EPT0), immediately upon initiation (EPT1) and one month post orthodontic therapy (EPT2). The data were analysed by paired sample t-test and one-way ANOVA test (p<0.05).
Results: The mean values of sensibility threshold for all the experimental and control maxillary incisors at EPT0, EPT1, and EPT2 times were 28.5, 40.8, and 38.0, and 23.2, 23.5, and 22.7 units respectively. The mean values of sensibility threshold for all experimental teeth at EPT0, EPT1 and EPT2 times were statistically different by using Paired sample t-test (p<0.05). Statistical analysis using one-way ANOVA shows that there is a statistically significant difference between sensibility threshold when groups were compared with the control group (p<0.05).
Conclusion: Following application of orthodontic forces, physiological changes of the dental pulp could affect the neural response. Response thresholds to electrical stimulation are also increased and consequently the EPT may not initiate a response. This finding is not an indication of loss of pulp vitality because after a few weeks the response threshold decreases. Therefore, the results of electrical pulp testing need to be carefully interpreted and closely scrutinised in orthodontics.