Goel 2017.

Study characteristics
Methods	Study design: randomised, cross‐over trial Location: Ghaziabad, India Number of centres: 1 Recruitment period: not reported Funding source: self‐funded
Participants	Inclusion criteria: patients requiring impression of the maxillary arch; patients with Gagging Severity Index scores of 3 to 5 Exclusion criteria: not reported Age: 4 to 14 years old Gender: male: 17; female: 23 Number randomised: 40 Number evaluated: 40
Interventions	Intervention: diode laser with a penetration depth of few millimetres in a defocused continuous mode applied on P6 acupressure point (output 0.5 mW, wavelength 940 nm, energy 4J) Total number of intervention groups: 2 (cross‐over design): Group A: first impression without laser simulation followed by 30‐minute break and impression with laser stimulation (n = 20) Group B: first impression with laser simulation followed by 30‐minute break and impression without laser stimulation (n = 20) Control: no laser Duration of treatment: 1 minute Duration of follow‐up: no follow‐up
Outcomes	Completion of dental procedure: not reported Reduction in gagging as assessed by researcher/dentist: dichotomous: presence or absence of gagging Assessed by participant: not reported Health‐related quality of life: not reported Adverse effects: not reported
Notes	Sample size calculation: reported. Data from pilot study was used, pooled variance S2 = 1.58 and mean difference d = 1.385 Key conclusions of the study authors: "LLLT on PC6 point was found to be effective in lowering anxiety levels as observed by faces modified anxiety rating scale. Further, it was authenticated as the pulse rates were significantly reduced and oxygen saturation levels were significantly increased. Also, gag reflex was significantly controlled when LASER stimulation was done at PC6"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Method not reported. Quote: "The patients were randomly assigned into two groups Group A and Group B"
Allocation concealment (selection bias)	Unclear risk	Method not reported
Blinding of participants and personnel (performance bias) All outcomes	Unclear risk	Method not reported
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Method not reported
Incomplete outcome data (attrition bias) All outcomes	Low risk	No dropouts. All subjects completed the study
Selective reporting (reporting bias)	Low risk	All outcomes described were reported. Conclusions are in accordance with the results
Other bias	Unclear risk	We are not sure regarding the carry‐over effect of the laser treatment