Efficacy of Ibuprofen Gargle for Postoperative Pain After Mandibular Third Molar Extraction: Protocol for a Phase II, Placebo-Controlled, Double-Blind, Randomized Crossover Trial
Authors: Kakei Yasumasa , Ioroi Takeshi , Ito Takahiro , Okazaki Yutaro , Hasegawa Takumi , Yano Ikuko , Akashi Masaya 
Published: April 2022

Background
Extraction of mandibular third molars is one of the most commonly performed oral surgical procedures, and nonsteroidal anti-inflammatory drugs (NSAIDs) are widely used for pain management. Oral NSAIDs are associated with adverse events such as gastrointestinal disorders, renal and hepatic dysfunction, and platelet dysfunction. Topical analgesics have been proposed as alternatives to oral and injectable medications to safely improve postoperative pain relief. We will conduct a single-center, placebo-controlled, double-blind, randomized crossover trial to assess the pain-relieving effect of an ibuprofen-containing gargle in patients undergoing extraction of mandibular third molars when compared with a placebo gargle.

Objective
This will be the first clinical study to compare the efficacy of an ibuprofen gargle with that of a placebo for relieving postoperative pain in addition to loxoprofen after mandibular third molar extraction.

Methods
This study will be performed at Kobe University Hospital. Participants (N=40) will be randomized equally to 1 of 2 groups. The ibuprofen-placebo group will receive an ibuprofen gargle on postoperative day (POD) 1 and a placebo gargle on POD 2. The placebo-ibuprofen group will receive a placebo gargle on POD 1 and an ibuprofen gargle on POD 2. Both groups will receive ibuprofen gargles on PODs 3-5 at least once daily. The primary objective is to estimate the within-subject difference on a visual analog scale (VAS) before and 5 minutes after using the ibuprofen or placebo gargle on PODs 1 and 2. The secondary objectives are to estimate the within-subject differences in ΔVAS before and 15 minutes after using the ibuprofen or placebo gargle on PODs 1 and 2, ΔVAS before and 5 or 15 minutes after using the ibuprofen gargle on PODs 3-5, overall efficacy (self-completion, 5 scales) on PODs 1-5, daily frequency of use (ibuprofen or placebo gargle and analgesics) on PODs 1-7, and the occurrence of adverse events.

Results
The Certified Review Board of Kobe University approved the study. The intervention was implemented in May 2021. For the primary analysis, we will calculate the mean and SD of ΔVAS5 on PODs 1 and 2 and the within-study difference in ΔVAS5. The treatment effect will be estimated by dividing the mean ΔVAS5 in the within-subject difference by 2 and calculating the P value using an unpaired t test. For the secondary analysis, we will calculate the mean and SD of ΔVAS15 on PODs 1 and 2 and the within-study difference in ΔVAS15. The treatment effect will be estimated as in the primary analysis.

Conclusions
This trial will provide exploratory evidence of the efficacy and safety of an ibuprofen gargle for pain reduction after mandibular third molar extraction.

Trial Registration
Japan Registry of Clinical Trials jRCTs051210022; https://tinyurl.com/39ej23zu

International Registered Report Identifier (IRRID)
DERR1-10.2196/35533