Data collection
SECONDARY, DISEASE TRANSMISSION
The research design was a block-randomized controlled trial. After enrollment, 70 participants were randomly and blindly assigned to use either 10% trehalose intervention, or CMC oral solution control group. Before intervention (day 0), the participants were interviewed for the XeQoLs questionnaire and demographic data. Then, unstimulated saliva was collected by spitting into a 50-mL Eppendorf tube for 5 min and was calculated to unstimulated salivary flow rate (mL/min) (AP). Salivary pH was measured with a pH meter (HI 98,100 Checker Plus, HANNA Instruments, Thailand). To prevent contamination and disease transmission, saliva volume was measured after centrifugation in the biosafety tissue culture hood (KP).Previously, a random allocation sequence was generated using a random-numbers table with a block size of 10 based on an estimated number of participants per week. The bottles of oral spray were sequentially numbered (KP) to be given to participants. The bottle of oral spray had no label so that the allocation was concealed to both patients and the researcher (AP). Participants were then instructed to use oral spray 4 times a day, after each meal and before bedtime. Each time, two pumps (approximately 0.4 mL) were intraorally applied. After 14 days of intervention (day 14), all participants were interviewed by phone using the XeQoLs questionnaire (KP), and VAS scores were recorded as a primary outcome by one researcher (KP). Because of COVID-19 pandemic, only some participants came back for saliva collection post treatment. Salivary pH and unstimulated salivary flow rate were recorded as secondary outcomes (KP). The sequential numbers on the bottles remained blinded to the researcher (AP) throughout the data collection phase.