Table 1.

Summary of measurement methods of saliva flow rate.

Type	Methods	Procedure	Pros	Cons
Unstimulated whole saliva [UWS]	Draining method	Allow the saliva to flow naturally down the lower lip and collect it in a graduated container [21]	No effect of slow rate [25] More representative of unstimulated secretion [25] Good repeatability [11] Easy use [11]	Time-consuming [26] Unattractive [26] Remaining saliva in oral [27] Need good collaboration [25]
	Spitting Method	Allow the saliva to cumulate at the bottom of the mouth for a while and then spit into a graduated container [21]	Less evaporation of saliva [25] Good repeatability [11] Easy use [11]	Time-consuming [26] Unattractive [26] Incomplete spit [27] Stimulatory effects [25] Need good collaboration [25]
	Swab method	Allow the saliva to be absorbed with pre-weighed cotton rolls and reweighed at the end of the collection period [21]	Low cost [25] Easy use [25] Suitable for less- or non-collaborative patients [25]	Risk of swallowing [25] Possible stimulatory effect [28]
	Suction method	Allow the saliva to be sucked into a graduated container by a negative pressure suction device in the closed or open suction method [21]	High reliability [29] Time-saving [29] No strict demands for Collaboration [29]	Require skilled personnel [29] Possible stimulatory effect [28]
	BokaFlo™	Place BokaFlo™ disposable device under the subject's tongue to collect saliva, then the device was removed and placed on the BokaFlo™ instrument for measurement [30]	High sensitivity [30] High specificity [30] Comfortable [30] Time-saving [30]	Underestimate saliva flow rate [30]
Stimulated whole saliva [SWS]	Acid stimulation method	Place a solution of 2% citric acid on each side of the tongue every 30 seconds for five minutes and collect saliva [21]	Get more saliva in a short time [31]	Change the composition of saliva [25] Change salivary pH [25] Need collaboration [25]
	Chewing method	Collect saliva after chewing an unflavored gum base or paraffin wax [21]	Get more saliva in a short time [31]	Change the composition of saliva [25] Change salivary pH [25] Uncontrollable chewing force and force duration [32]
Major salivary gland	Parotid gland	Place the Lashley cup at the mouth of the parotid gland catheter to collect saliva from the parotid gland [32]	Not invasive [25]	Time-consuming [33] Complex procedure [33] Required skilled personnel [33]
	Submandibular gland and sublingual gland	Use a Wolff saliva collector to collect saliva from the submandibular and sublingual gland [32]	Not invasive [33]	Time-consuming [33] Complex procedure [33] Require skilled personnel [33]
Minor salivary gland	Iodine-starch filter paper method	Place the iodine-starch filter paper on the lower lip for a period of time and then scan and digitize with an image scanner [34]	Comfortable [34] Easy use [34] Larger area of lower lip [34]	No large volume collected [34] Contain harmful iodine [34] Not for people allergic to iodine [34]
	Electronic sialometry device	Measure the electrical resistance of a filter paper that has absorbed saliva, providing an estimate of saliva volume [35]	Easy use [35] Low cost [35] Quick [34]	No large volume collected [35]
	Standard filter paper	Place a standard filter paper on the buccal mucosa to absorb saliva and weigh it [36]	Not invasive [25] Easy use [36]	No large volume collected [36]