Elbay 2016.

Study characteristics
Methods	Study design: randomised, controlled, double‐blind, split‐mouth, clinical trial Location: Kocaeli University, Turkey Number of centres: 1 Recruitment period: not reported Funding source: not reported
Participants	Inclusion criteria: patients requiring bilateral periapical radiographs of the maxillary molar region; patients with moderate to very severe gagging according to the Classification of Gagging Problem (CGP) index Exclusion criteria: parents who were unwilling to implement the DAS for their children; children with unco‐operative attitudes, disabilities, or severe systemic diseases; children requiring emergency treatment Age: children 6 to 12 years old. Mean age group: 8.68 years Gender: male: 17; female: 8 Number randomised: 25 Number evaluated: 25
Interventions	Intervention: low‐level laser therapy (LLLT) at P6 point (laser energy of 300 mW (energy density = 4 J/cm2) for 14 seconds on each P6 point) Control: without application of LLLT on P6 Duration of treatment: 14 seconds Duration of follow‐up: not reported
Outcomes	Reduction in gagging leading to completion of dental procedures ‐ as assessed by researcher/dentist using gagging severity score: Category 0: no/mild ‐ gagging did not occur or was so mild that it could be controlled by the patient without difficulty Category 1: moderate ‐ the patient had obvious difficulties controlling reflexes, but the radiographic procedure was completed with correct film placement. The operator could utilize prophylactic and suppressive precautions Category 2: severe ‐ the patient violently reacted to film placement and might remove the film after insertion. Film placement required several attempts. The operator could utilize any precaution including anaesthetic spray. Radiography was completed, possibly with modified film placement or using an alternative intraoral technique Category 3: worst ‐ total refusal, occasional vomiting. An intraoral radiograph from the region in question was unobtainable Assessed by participant: not reported Health‐related quality of life: not reported Adverse effects: none reported
Notes	Sample size calculation: minimum sample size of 22 was calculated using the G*Power software program (version 3.1.9.2; power 0.80, α = 0.05, β = 0.20). Therefore, considering possible dropouts, this study was conducted with 25 children Key conclusions of the study authors: "Both mean and median gagging scores were higher in the control group than in the experimental group. Patients who were unable to tolerate the intraoral control radiography were able to tolerate the procedure after LLLT. Differences between gagging scores of the control and experimental groups were statistically significant (P = .000). There was no significant correlation between gagging severity and anxiety score (P > .05). A negative correlation was found between age and gagging score in the control group (P.05). Within the limitations of this study, LLLT of the PC 6 acupuncture points appears to be a useful technique for controlling the gag reflex in children during maxillary radiography"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "A computer generated list was used to randomly select the control and experimental sides" Comment: done
Allocation concealment (selection bias)	Unclear risk	Not reported
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Quotes: "In order to blind patients to the LLLT, laser application was simulated using a non‐working laser for the control radiograph.." "All laser treatment was performed by a single operator who did not perform the radiography or gagging evaluation" Comment: done. Laser application was simulated using non‐working laser for control followed by actual laser for experimental. Both patients and operator wore protective eye wear regardless of laser activation
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "All laser treatment was performed by a single operator who did not perform the radiography or gagging evaluation"
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