Table 1.

PICOS criteria for study inclusion

Parameter	Inclusion criteria	Exclusion criteria
Population	Patients with a diagnosis of BMS according to the International Classification of Headache Disorders-3 (ICHD-3) [29]: patients presenting symptoms of oral burning or pain lasting more than 2 h per day for more than 3 months	Any local or systemic factors that could produce the symptoms of oral burning pain, such as oral infections, oral lichen planus, or oral candidiasis
Intervention	LLLT (600–1100 nm) was delivered directly to the site of pain; no limitations were placed on exposure duration or distance
Comparator	No treatment or other treatments
Outcomes	Primary outcome: 1) Burning pain, measured using the Visual Analog Scale (VAS) Secondary outcomes: 1) Oral health-related quality of life, assessed by the Oral Health Impact Profile-14 (OHIP-14); 2) Negative emotions, measured using the Hospital Anxiety and Depression Scale (HADS); 3) Other relevant outcomes and serious adverse events
Study design	1) Randomized controlled trials; 2) Published in English	1) Observational studies; 2) Non-randomized controlled trials; 3) Other types of studies