Quantitative Assessment of Mechanical Allodynia and Central Sensitization in Endodontic Patients

Introduction: Patients seeking endodontic treatment commonly present with reduced mechanical pain thresholds (ie, mechanical allodynia [MA]) in the offending teeth. In patients with moderate to severe pain, MA may manifest in the teeth contralateral to the offending teeth because of the onset of central sensitization (CS). We hypothesize that there are quantitative differences in MA and CS in patients with different pulp and periradicular diagnoses. Methods: Patients (n = 70) receiving endodontic treatment in the graduate endodontic clinic at the University of Texas Health Science Center at San Antonio and healthy volunteers (n = 10) were included in this cross-sectional study. The mechanical pain threshold from molar teeth was measured by a digital bite force transducer on the offending tooth (ipsilateral) and the contralateral tooth. Ipsi- and contralateral MA among different endodontic diagnoses were analyzed using the Kruskal-Wallis with Dunn post hoc test and the Student t test for differences between sexes. Multivariate regression models analyzed predictors for MA and CS. Results: Periradicular diagnoses of asymptomatic apical periodontitis, symptomatic apical periodontitis, and chronic apical abscess cases were significantly associated with MA. CS, seen as contralateral MA, was only detected in pulpal diagnosis of symptomatic irreversible pulpitis, previously initiated treatment, symptomatic apical periodontitis, and chronic apical abscess. Females experienced significantly lower pain thresholds than males on both sides. MA and CS were significantly correlated in both sexes. The preoperative pain level and duration were significant predictors for MA and CS only in female patients. Lastly, age was a significant predictor for MA in females. Conclusions: The magnitude of MA and CS varied with different endodontic diagnoses, with CS being correlated with increases in MA. Only in female patients were age, preoperative pain duration, and intensity significant predictors for the development of MA and CS.