Effectiveness of Hydrogen Water Intervention on Acute Oral Inflammation, Oral Microbiota, and Pain Following Free Flap Reconstruction in Patients With Oral Cancer

The research team explains the study purpose, intervention, possible risks, and participant rights to the participant (and/or legally authorized representative) in person and provides written information. After questions are answered and the informed consent form is signed, the participant is enrolled and randomly assigned by a computer-generated randomization table in a 1:1 ratio to the experimental group (hydrogen water oral care, n = 18) or the control group (boiled water oral care, n = 18).

The hydrogen water is produced on site by the research team using a nano hydrogen water machine (electrolytic reduction, nano micro-bubbles), with an average concentration of 1.1 mg/L, an oxidation-reduction potential of about -550 mV, and a hydrogen concentration shown to remain stable for 12 hours. The principal investigator prepares the hydrogen water twice a day. The hydrogen water and the boiled water are dispensed into bottles labeled only with the date and time, and are received and distributed by the research team nurse.

Oral condition is assessed with the Oral Assessment Guide (OAG; 8 items: voice, swallowing, lips, tongue, saliva, mucous membranes, gingiva, and teeth or dentures; each scored 1-3; total score 8-24), and the frequency of oral care is based on the OAG score: 8, once per shift; 9-10, every 4 hours; 11-24, every 2 hours. The first oral care is performed by the ward nurse according to ward routine, who also teaches the primary caregiver the correct procedure; after the caregiver can perform it proficiently, subsequent oral care is performed daily by the primary caregiver according to the schedule. The research team nurse checks the procedure daily and provides guidance and correction when needed. Oral care is performed with a sterile sponge toothbrush dipped in the assigned solution, gently brushing the oral mucosa, the upper and lower jaws, and the tongue surface, avoiding mechanical irritation, for 7 days. The control group uses boiled water in the same manner and at the same frequency, so that only the liquid differs between groups. The research team records the implementation and the patient's oral reactions daily. Both groups receive the same postoperative care and health education in the plastic surgery ward.

Saliva samples are collected on the day of transfer from the intensive care unit to the plastic surgery ward, immediately after group allocation (T0), and on Day 3 (T1) and Day 7 (T2) of the intervention. All saliva samples are collected in the morning, 30 minutes after oral care, by natural absorption with a syringe or a cotton roll placed in the mouth; participants do not eat, drink, or brush their teeth for 30 minutes before collection. At least 2 mL of saliva is collected in a sterile centrifuge tube and frozen within 30 minutes. IL-1β, IL-6, TNF-α, and IL-10 are quantified with LEGENDplex, and the oral microbiota is analyzed by 16S rRNA gene region analysis. Pain is assessed once daily with the Brief Pain Inventory-Taiwan (BPI-T).