Effects of the highly COX-2-selective analgesic NSAID etoricoxib on the rate of orthodontic tooth movement and cranial growth.

BACKGROUND: NSAID analgesics have found widespread use in the treatment of pain, inflammation and fever. The highly COX-2-selective NSAID etoricoxib has shown a favorable side effect profile and excellent analgesic efficacy, particularly for dental and orthodontic pain, surpassing the current standard analgesic in orthodontics, acetaminophen. However, potential side effects on the rate of orthodontic tooth movement (OTM) and cranial growth, relevant for clinical usability during orthodontic treatment, have not yet been investigated.

MATERIAL AND METHODS: 40 male Fischer344 rats were randomly assigned to 4 groups (n=10) - controls receiving only 1.5ml tap water per day by oral gavage for a total of 5 weeks (1) as well as rats receiving an additional daily normal etoricoxib dosage of 7.8mg/kg for 3d (2) and 7d/week (3) and a high dosage of 13.1mg/kg for 7d/week (4) with serum bioavailability assessed by liquid chromatography-mass spectrometry. After one week of premedication, the first upper left molars (M1) were moved orthodontically in anterior direction for 4 weeks using a closed NiTi coil spring (0.25N) and OTM as well as sagittal cranial growth were quantified cephalometrically by CBCT imaging at the start and end of OTM.

RESULTS: OTM, quantified as anterior metric tipping of M1, was significantly inhibited by about 33% only in rats receiving high-dose etoricoxib 7d/week (p=0.046) with a respective, but insignificant tendency also detectable for the normal dosages, whereas sagittal cranial growth was by tendency slightly increased with rising etoricoxib dosages, reflected by corresponding steady-state serum concentrations, confirming etoricoxib bioavailability.

CONCLUSIONS: An etoricoxib-induced clinically relevant deceleration of OTM is not to be expected at dosage regimens used in clinical practice to treat dental or orthodontic pain in contrast to a continuously administered high dosage. Due to its favorable side effect profile and higher analgesic efficiency regarding dental and orthodontic pain, etoricoxib should be a clinically valid alternative to the current standard orthodontic analgesic acetaminophen with its associated higher risk profile.