Background & Aims
Pulpitis is an acute clinical condition, often symptomatic, characterized by a significant pain profile, and represents one of the primary reasons for patients to seek urgent dental care. The presence of persistent pain, commonly reported in acute pulpitis, results in changes in mood, social behavior, and the response to acute or chronic nociceptive stimuli, along with alterations in pro-inflammatory cytokines. However, this association of inflammatory conditions and behavioral changes, concerning pulpal pathologies still is considerable gap in the literature. In this context, the use of animal models is useful to reproduce validated analysis parameters of acute conditions and behavioral alterations. This study assessed the inflammatory effects during the development of experimentally induced pulpitis in mice on emotional state alterations, nociception, food consumption, and mechanical sensitivity.
Methods
The Ethics Committee on Animal Use (231.1.395.59.0) approved this study. A total of 48 wild-type isogenic mice of the Mus musculus (C57BL/6) were used and divided in 2 groups (n=24): G1: experimental and G2: control (n=24). The mice were received at an age between 5 and 7 weeks, with an average weight of 20g, and were housed in groups of 4 animals per cage. For pulpitis induction, the animals were anesthetized, and the lower right first molar was accessed using a 1/4 drill. A 10 µm solution of Escherichia coli LPS (1 µg/µL) was inoculated, and the access was sealed using glass ionomer. The animals underwent open field tests (anxious state and locomotor activity), formalin tests (nociception evaluation), and von Frey tests (mechanical sensitivity assessment). Euthanasia was scheduled on days 2, 5, and 10 post pulp access. The animals had their normal/sucrose water consumption, food intake, and weight checked daily. Data were analyzed using ANOVA and Tukey’s post-test (p<0.05).
Results
Intra-examiner agreement values were excellent (>0.70). Regarding food consumption, a significant difference was identified between G1 and G2 at days 1 (5.3 ± 2.25, 16.1 ± 1.46), 2 (11.3 ± 1.51, 16.0 ± 2.38) and 4 (15.0 ± 2.94, 16.6 ± 2.49), and between groups and days at days 2 and 4; water consumption showed difference among the G1 and G2 at days 4, 5, 9 and 10 (p<0.05). Weight gain showed difference between G1 and G2 (p<0.05). For mechanical sensitivity, differences were observed between groups (p<0.001) and between days 0 (9.19 ± 1.26, 8.55 ± 1.61), 1 (6.36 ± 1.22, 9.13 ± 1.21) and 10 (8.11 ± 1.22, 9.58 ± 0.57) (p<0.05). No significant difference was identified in locomotor activity (p>0.05), and a difference was observed between groups and days 2 (21.8 ± 7.88, 37.5 ± 21.8), 5 (34.8 ± 11.8, 50.6 ± 15.1), and 10 (36.8 ± 10.8, 47.1 ± 13.5) in the center time (p<0.05). The nociception indicated a difference only between days (p<0.05), with no difference between groups (p>0.05).
Conclusions
According to the methods employed, this study allowed us to conclude that there are statistically significant differences in emotional state alteration, mechanical sensitivity, and nociception in the proposed animal model. Acute pulpitis is a pathological condition capable to induce behavior changes based on the animal model tested, with potential interference at central sensibilization.
References
Allareddy, V., et al. “Hospital-Based Emergency Department Visits Involving Dental Conditions?: Profile and Predictors of Poor Outcomes and Resource Utilization.” Journal of the American Dental Association 145 (4): 331–37.
Cazuza, R. A., et al. “Effects of Treatment with a Carbon Monoxide Donor and an Activator of Heme Oxygenase 1 on the Nociceptive, Apoptotic and/or Oxidative Alterations Induced by Persistent Inflammatory Pain in the Central Nervous System of Mice.” Brain Research Bulletin 188 (January): 169–78.
Coral-Pérez, S., et al. “Treatment with Hydrogen-Rich Water Improves the Nociceptive and Anxio-Depressive-like Behaviors Associated with Chronic Inflammatory Pain in Mice.” Antioxidants 11 (11): 2153.
Raoof, M., et al. Effect of chronic stress on capsaicin-induced dental nociception in a model of pulpitis in rats. Archives of oral biology, 85, 154-159.
Tsuboi, Y., et al. Modulation of astroglial glutamine synthetase activity affects nociceptive behaviour and central sensitization of medullary dorsal horn nociceptive neurons in a rat model of chronic pulpitis. European Journal of Neuroscience, 34(2), 292-302.
Presenting Author
Jardel Francisco Mazzi-Chaves
Poster Authors
Jardel Mazzi-Chaves PhD
Prof. Dr
University of São Paulo
Lead Author
Fabiane Lopes-Olhê PhD
University of São Paulo
Lead Author
Manoel Sousa-Neto PhD
University of São Paulo
Lead Author
Francisco Paula-Silva PhD
University of São Paulo
Lead Author
Iago Ramirez
MSc
Universidade de São Paulo
Lead Author
Igor Petean PhD
University of São Paulo
Lead Author
Topics
- Mechanisms: Psychosocial and Biopsychosocial