Preoperative and Postoperative Hyperalgesia in Dental Patients on Chronic Opioid Therapy: A Pilot Study.

OBJECTIVE: Opioid-induced hyperalgesia, a paradoxical increase in pain sensitivity associated with ongoing opioid use, may worsen the postoperative pain experience. This pilot study examined the effect of chronic opioid use on pain responses in patients undergoing a standardized dental surgery. METHODS: Experimental and subjective pain responses were compared prior to and immediately following planned multiple tooth extractions between patients with chronic pain on opioid therapy (≥30 mg morphine equivalents/d) and opioid-naïve patients without chronic pain matched on sex, race, age, and degree of surgical trauma. RESULTS: Preoperatively, chronic opioid users rated experimental pain as more severe and appreciated less central modulation of that pain than did opioid-naïve participants. Postoperatively, chronic opioid-using patients rated their pain as more severe during the first 48 hours and used almost twice as many postoperative analgesic doses during the first 72 hours as the opioid-naïve controls. CONCLUSION: These data suggest that patients with chronic pain taking opioids approach surgical interventions with heightened pain sensitivity and have a more severe postoperative pain experience, providing evidence that their complaints of postoperative pain should be taken seriously and managed appropriately.

2-Hydroxyethyl methacrylate inhibits migration of dental pulp stem cells.

INTRODUCTION: Cell migration is an important step in pulpal wound healing. Although components in the resin-based dental materials are known to have adverse effects on pulp wound healing including proliferation and mineralization, their effects on cell migration have been scarcely examined. Here, we investigated the effects of 2-hydroxyethyl methacrylate (HEMA) on the migration of dental pulp stem cells (DPSC) in vitro. METHODS: Cell viability was assessed using the MTT (3-(4, 5-dimethylthiazolyl-2)-2, 5-diphenyltetrazolium bromide) assay, and cell migration was evaluated using the wound scratch assay and transwell migration assay at noncytotoxic doses. The Western blot was used to examine pathways associated with migration such as focal adhesion kinase, mitogen-activated protein kinase, and glycogen synthase kinase 3. RESULTS: There were no drastic changes in the cell viability below 3 mmol/L HEMA. When DPSCs were treated with HEMA at 0.5, 1.0, and 2.5 mmol/L, cell migration was diminished. HEMA-treated DPSCs exhibited the loss of phosphorylated focal adhesion kinase in a dose-dependent manner. The HEMA-mediated inhibition of cell migration was associated with phosphorylation of p38 but not glycogen synthase kinase 3, Extracellular signal-related kinase (ERK), or c-Jun N-terminal kinase (JNK) pathways. When we inhibited the p38 signaling pathway using a p38 inhibitor, the migration of DPSCs was suppressed. CONCLUSIONS: HEMA inhibits the migration of dental pulp cells in vitro, suggesting that poor pulpal wound healing under resin-based dental materials may be caused, in part, by the inhibition of cell migration by HEMA.