The objective of this review of the literature is to summarize the physiology of orofacial pain in dentistry, particularly physiology of the pain pathway and molecular mechanisms on pathophysiology of pain, on account of new insights into classification of orofacial pain related diseases. This article will also focus on possible mechanisms of neuropathic orofacial pain which is distinguished from other types of pain.

To investigate the effect of a standardized extract of Centella asiatica (ECa 233), which has anti-inflammatory properties, on the local expression of the transient receptor potential vanilloid 1 (TRPV1), the acid-sensing ion channel subunit 3 (ASIC3), and the calcitonin gene-related peptide (CGRP) in the temporomandibular joint (TMJ) structure 21 days after injecting the TMJ with complete Freund’s adjuvant (CFA). A mouse model was induced by analyzing the CFA-injected TMJ on days 7, 14, and 21. We assessed TMJ histology by the osteoarthritis cartilage grade score. Then, we observed the effect of different ECa 233 concentrations (30, 100, and 300 mg/kg) and of 140 mg/kg ibuprofen doses on TRPV1, ASIC3, and CGRP local expression on day 21. Osteoarthritis cartilage scores were 1.17±0.37 and 3.83±0.68 on days 14 and 21, respectively, in the CFA group (n=5). On day 21, TRPV1, ASIC3, and CGRP expression significantly increased in the CFA group. In the ibuprofen-treated group, TRPV1 expression significantly decreased, but ASIC3 and CGRP showed no significant difference. All ECa 233 doses reduced TRPV1 expression, but the 100 mg/kg ECa 233 dose significantly decreased ASIC3 expression. TRPV1, ASIC3, and CGRP expression increased in mice with TMJ-OA on day 21. All ECa 233 and ibuprofen doses inhibited pathogenesis by modulating the local expression of TRPV1 and ASIC3. Therefore, ECa 233 was more effective than ibuprofen.

Mirror-image pain is a kind of pain that occurs on the contralateral side, but its pathogenesis remains unclear. Objective To develop an osteoarthritis mouse model for investigating mirror-image pain through observing nocifensive behaviors, histological changes, and nociceptive activity at days 3, 7, 14, 21, and 28 after the chemical induction of unilateral temporomandibular joint (TMJ) osteoarthritis. Methodology We randomly divided 6-week-old mice into sham and complete Freund adjuvant groups. To induce nocifensive behaviors, we applied 0.04 g of von Frey filament, 10 psi of air puff, and cold acetone on both sides of whisker pads at different days. The histology of TMJ on both sides was observed by hematoxylin/eosin staining and microcomputed tomography scanning. Furthermore, the nociceptive activity was evaluated using the phosphorylated cyclic AMP response element binding protein (pCREB) and a microglia marker at different days in the trigeminal subnucleus caudalis. Results Nocifensive behaviors against mechanical and temperature stimuli on the contralateral side became stronger than the baseline on day 28, in agreement with the elevation of the pCREB and the microglia marker in the trigeminal subnucleus caudalis. Thus, hypernociception on the contralateral side occurred at day 28. Conclusions Clearly, the TMJ model with unilateral osteoarthritis exhibited mirror-image pain. Therefore, this model is useful in investigating the pathogenesis of pain and in developing treatments.

Purpose: This study aimed to investigate the minimum inhibitory concentration (MIC) and biological properties of modified glass-ionomer cement (BIO-GIC) supplemented with chlorhexidine diacetate (CHX).Methods: The BIO-GIC was originally a combining formulation of conventional glass-ionomer cement, chitosan, albumin and tricalcium phosphate. CHX was incorporated at various concentrations of 1.25%, 2%, 2.5%, 5%, 7.5% and 10%. Antimicrobial activity against certain microorganisms related to cariogenesis Streptococcus mutans (S. mutans), Streptococcus sanguinis (S. sanguinis), and Enterococcus faecalis (E. faecalis), was evaluated by microdilution test. One effective concentration of CHX was mixed with Penaeus merguiensis-Translationally Controlled Tumor Protein (Pmer-TCTP) and further conducted by biological tests including cell viability and mineralization in dental pulp.Results: S. mutans were inhibited at 7.5% CHX-modified BIO-GIC, while S. sanguinis and E. faecalis showed no inhibition at any concentration. Cell viability significantly decreased with 7.5% CHX-modified BIO-GIC after 72 h. Dental pulp exposed to this group formed smaller and fewer calcium nodules but adding Pmer-TCTP reduced cell death and slightly enhanced mineralization.Conclusion: 7.5% CHX-modified BIO-GIC shows potential for inhibiting S. mutans and having potential cell viability and mineralization in dental pulp cells.

Temporomandibular disorders (TMDs) are multifactorial musculoskeletal conditions involving the temporomandibular joints, masticatory muscles, and associated craniofacial structures [1]. Although hi...