Evaluation of Animal Wellfare in a Mechanically Induced Pulpitis Model

Objectives: Evaluate the animal welfare in the mechanically induced pulpitis model (PIM) in rats,
for intradental application of potentially anti-inflammatory/regenerating compounds,
avoiding the use of analgesics that mask a cellular answer and that will allow understand the associated mechanisms to the late inflammatory pain to the PIM.
Methods: This study was approved by the Institutional Care and Use of Animals Committee IACUC from PUJ (Pontificia Universidad Javeriana). Previously an ethogram of basal conditions behaviour and weight increase curve was performed. Under an anaesthesia protocol with 2,5% Isoflurane a PIM method was established In-vivo in male Lewis rats raging 3.5-4 months of age (350-400g). The PIM was done through rotational instruments in eight conditions and the later sealing of the cavity: with or without administering subcutaneous 2% lidocaine, with or without Capsaicin, sealing with amalgam or Zinc phosphate and control groups, individuals without PIM with anaesthesia, with or without lidocaine. To determine the loss of the welfare behaviour was evaluated from the individuals during the seven days following the Rifai, Grimace, Frecknell scales under the double blinded method and the pain, distress and discomfort identification format. The weight variation results were analysed through an ANOVA with the Graph Pad Prism program.
Results: During the PIM procedure no modifications in the vital signs were observed. In the following seven days to the PIM, there wasn’t a loss of welfare associated to pain obtaining resulting scores of zero in the applied scales. Regarding the weight, no significant variations were presented from the beginning until the end of the evaluation period.
Conclusions: A pulpitis mechanical induction model was implemented in rats that without affecting the welfare, allows the application of compounds with anti-inflammatory/regenerating potential. Under the conditions of this study the analgesic therapy won’t be necessary.