Yilmaz 2011c.

Study characteristics
Methods	Study type: RCT (split‐mouth, 4 groups) Duration of trial: not mentioned in the study Duration of follow‐up: 6 months
Participants	Setting: Department of Periodontology, Near East University, Turkey Inclusion criteria: patients had to have followed the periodontal maintenance program for > 1 year. They would have been initially diagnosed with chronic periodontitis or gingivitis with gingival recession (maximum 3 mm). The subjects had to have 4 or more hypersensitive teeth at different quadrants Exclusion criteria: criteria for exclusion from the study were carious lesions on the selected or neighboring teeth, defective restorations, any professional desensitizing therapy on the selected teeth during the last 6 months, use of desensitizing toothpaste in the last 3 months, taking analgesics/anti‐inflammatory drugs at the time of the study, pregnancy, and smoking Total number: 48 participants with 244 teeth enrolled and completed Age range: 18 to 58 years (mean age: 41 years) Sex (M/F): 22/26
Interventions	Group 1: GaAlAs laser Details: low‐level laser therapy was performed with GaAlAs diode laser (LaserSmile, Biolase Technology, Irvine, CA) with continuous emission (810 nm) on non‐contact mode (2 mm from the surface). The laser device was used with the following parameters: output power of 500 mW, irradiation time of 60 s, and 3.5 cm2 area of active tip resulting in an energy density of 8.5 J/cm2 Group 2: placebo laser Details: in the placebo laser group, the same GaAlAs laser without laser emission was used. GaAlAs laser was applied by scanning the cervical part in an overlapping pattern Group 3: NaF varnish Details: in the NaF varnish group (Voco, Cuxhaven, Germany), the light yellow varnish was applied with a disposable brush at the cervical region of both the buccal and lingual surfaces strictly, ensuring dry tooth surface by isolation with cotton rolls and an air syringe. The patients were instructed not to eat/drink or brush their teeth for 1 hour following the varnish application, as suggested by the manufacturer Group 4: placebo NaF varnish Details: in the placebo NaF varnish group, the same treatment procedures were performed with a saline solution that was in dark brown bottle like the NaF varnish bottle
Outcomes	Responses to air blast stimuli (VAS) at baseline, and immediately after, 1 week, 1 month, 3 months, 6 months after intervention
Notes	Baseline characteristics: the vitality of all experimental teeth was controlled at the beginning and end of the trial by means of an electric pulp tester (Digitest, Parkel, NY). Prior to the application of laser and NaF varnish, dentine hypersensitivity was assessed by an evaporative stimulus. A cold air blast from a dental syringe was directed to the exposed cervical area for 3 s at a distance of 1 cm and at a right angle to the buccal site of the assigned teeth, while the adjacent teeth were isolated with cotton rolls. Patients were asked to record their overall sensitivity by marking a point on a 10 cm VAS, anchored at each end by the phrases ‘no pain’ and ‘unbearable pain.’ After all stimuli, a separate sheet of paper containing the printed VAS was given to the patient so that patients could not be influenced by the previous results. Data from the VAS were recorded by measuring the distance between 0 point and the sign marked by the patient in millimeters on the 10‐cm line. Only patients with baseline VAS scores > 4 were included in the study. All stimuli were given by 1 operator on the same dental chair with the same equipment yielding similar air (55 to 60 ѱ) and temperature (21 to 22℃) each time Sample size calculation: quote: "A minimum clinically significant difference in VAS scores of 0.6 was determined from a previous study on DH. The power analysis was done based on this minimum clinically significant difference in VAS scores, using a at level 0.05, at 80% power, and a σ of 1.12. According to these data, the number of patients required to be involved to conduct this study was calculated as 40" Source of funding: not mentioned in the study Ethics approval: quote: "Study protocol and related consent forms were approved by Institutional Review Board of Near East University" Informed consent: quote: "After having received oral and written information about the intention and design of the study, and having signed the informed consent form, the subjects were included in the study" Adverse events: none. Quote: "No complications such as detrimental pulpal effects or allergic reactions were observed"
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Quote: "In this split‐mouth study for each patient, selected teeth were randomly assigned to the GaAlAs laser group, placebo laser group, NaF varnish group, and the placebo NaF varnish group by lottery method" Comment: probably done
Allocation concealment (selection bias)	Unclear risk	Insufficient information provided
Blinding of participants and personnel (performance bias) All outcomes	Low risk	Use of placebos might reduce performance bias
Blinding of outcome assessment (detection bias) All outcomes	Low risk	Quote: "DH was assessed with VAS; immediately, at 1 week, and at 1, 3, and 6 months after treatments by a single examiner who was not aware of the type of treatment applied" Comment: adequate
Incomplete outcome data (attrition bias) All outcomes	Low risk	No loss to follow‐up
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 Source of funding was not mentioned in the study