Vieira 2009.

Study characteristics
Methods	Study type: RCT (split‐mouth, 3 groups) Duration of trial: not mentioned in the study Duration of follow‐up: 3 months
Participants	Setting: Department of Restorative Dentistry, Federal University of Ceará, Fortaleza, Ceará, Brazil Inclusion criteria: patients who had good oral hygiene and at least 3 hypersensitive teeth Exclusion criteria: patients who had severe systemic and/or psychological diseases, constant use of analgesic and/or anti‐inflammatory drugs, or allergic responses to dental products; patients who used any desensitizing agents and/or submitted to periodontal surgery or scaling in the 6 months before enrolment; teeth which had carious lesions, defective restorations, cracks or fractures, premature contact, prosthesis or orthodontics appliances, periodontal pockets, mobility, or evidence of pulpitis Total number: 30 participants with 164 teeth enrolled, 24 participants with unknown number of teeth completed Age range: 24 to 68 years Sex (M/F): 7/23
Interventions	Group 1: (58 teeth enrolled, unknown number of teeth completed) GaAlAs laser (wavelength: 660 nm; output 30 mW; duration 2 minutes) Details: the treatments were applied under relative isolation by 1 experienced operator other than the examiner. The diode laser device was used on contact mode with the following parameters: continuous emission, 30 mW output power, wavelength of 660 nm, irradiation time of 120 s, and ray diameter of 3 mm resulting in an energy density of 4J/cm2. The laser beam was applied with the laser tip positioned perpendicularly to the tooth surface at 4 points: 1 to the apex (apical point) and 3 to the cervical area (mesio‐buccal, disto‐buccal, and lingual points) of the tooth Group 2: (55 teeth enrolled, unknown number of teeth completed) potassium oxalate gel (3%) Details: potassium oxalate gel was applied according to manufacturer's instructions: passive application, using a brush, for 2 minutes. During this period, the laser device was positioned but not activated Group 3: (51 teeth enrolled, unknown number of teeth completed) placebo gel Details: the placebo gel application followed this same procedure and the laser device was also positioned but not activated. (The treatment was repeated at 7‐day intervals for 4 consecutive weeks. 3 months after the 4th treatment session, patients were recalled for re‐assessment of dentinal hypersensitivity)
Outcomes	Responses to tactile (probe) and air blast stimuli (VAS) at baseline, and immediately, 3 months after intervention
Notes	Baseline characteristics: the degree of sensitivity was determined for each tooth in response to tactile (probe) and air blast stimuli. The probe stimulus was applied under slight manual pressure in the mesio‐distal direction on the cervical area of the tooth. The air blast was performed with an air syringe for 1 s at a distance of 1 cm from the tooth surface. Dentinal hypersensitivity was assessed by patient's indication of the amount of pain related to each tooth immediately after each stimulus, according to a VAS. The VAS was 10 cm long and, on the left and right ends, contained an indication of 'no pain' and 'severe pain,' respectively. The participants were instructed to the pain severity of each tooth elicited by the hydrodynamic stimuli. The sensitivity patterns were recorded at baseline and immediately after and 3 months after treatment by an examiner previously calibrated for applying the stimuli. The order in which the teeth were evaluated within each subject was maintained at each visit Sample size calculation: not mentioned in the study Source of funding: not mentioned in the study Ethics approval: quote: "The search protocol was approved by the Committee of Ethics in Research of Federal University of Ceará" Informed consent: quote: "Participants were informed about the purpose and design of the investigation and signed an appropriate informed consent form" Adverse events: none
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Unclear risk	Quote: "This randomisation was performed by placing all the selected teeth in a list and assigning treatment according to a predefined sequence: 1) laser, 2) potassium oxalate gel, and 3) placebo gel" Comment: insufficient information to permit judgement of low or high risk. Not clearly mentioned how random sequence generation was done
Allocation concealment (selection bias)	Unclear risk	Insufficient information provided
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Due to use of placebos, the study might be free of performance bias Comment: it was impossible to blind personnel in this study design, but the outcome is not likely to be influenced by lack of blinding
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "The examiner and the patients did not know, which type of treatment was applied to which tooth" Comment: adequate
Incomplete outcome data (attrition bias) All outcomes	Low risk	A loss to follow‐up of 6 out of 30 patients was reported in the study. However, since the study was a split‐mouth design, the outcomes would unlikely be influenced by the dropouts
Selective reporting (reporting bias)	Low risk	All intended outcomes were reported in the study
Other bias	Low risk	No other sources of bias were identified Sample size of calculation and source of funding were not mentioned in the study