Zhang 2013.

Methods	Design: split‐mouth randomised controlled clinical trial Centres: 1 Date: 2009 to 2011; the months were not reported Setting: secondary care Operators: treatments were provided by 1 doctor
Participants	Setting: University School of Dentistry Clinic Geographical area: China Sample: 53 children; 120 teeth Age: 3 to 15 years; mean age 8.6 years (SD 3.1) Sex: males 40% Baseline: participants with primary and permanent, anterior and molar teeth affected by unclassified caries in terms of dental surface location. The lesions depth varied by enamel to shallow or deep dentine. Methods used for caries diagnosis were not described. There was also a lack of information about pulpal vitality of decayed teeth Inclusion criteria: children who were generally healthy and had 2 teeth with caries of equivalent degree Exclusion criteria: clinical or radiological signs, or both of pulp infection involving tested teeth
Interventions	Intervention: Er:YAG laser: wavelength: 2.94 μm pulse energy: 100 mJ to 700 mJ pulse duration: 450 μsec repetition rate: 5 Hz to 20 Hz cooling method: water/air Control: sterile hand excavator and traditional drill in handpiece
Outcomes	Primary outcomes Caries removal: complete removal of the caries was assessed via visual and dentine hardness examination by using a sterile hand excavator Episodes of pain: measured by 6‐face rating scale: 0 = no hurt, 1 = hurts little bit, 2 = hurts little more, 3 = hurts even more, 4 = hurts whole lot, 5 = hurts worst Secondary outcomes Marginal integrity of restoration: the restorations were evaluated at 3, 6 or 12 months. Insufficient information was provided about the method and tools used Durability of restoration: the restorations were evaluated in 3, 6 or 12 months. Insufficient information was provided about the method and tools used Recurrent caries: not reported Pulpal inflammation or necrosis: not reported Participant discomfort: not reported Need for anaesthesia: all treatments were begun with anaesthesia; during treatment children could have local anaesthesia whenever they wanted Operator preference/fatigue in operator: not reported Participant preference: each child was asked to answer questions in a questionnaire including describing sensitivity during treatment as well as expressing their preference for further treatment Duration of treatment: generically referred to the duration of treatment or average amount of time spent performing a cavity preparation without specifying the starting and finishing times of treatment
Notes	Cavities were filled by resin (Filtek Z350, Z250, 3M Co., USA) Treatments were performed without local anaesthesia Funding: unclear
Risk of bias
Bias	Authors' judgement	Support for judgement
Random sequence generation (selection bias)	Low risk	Teeth were randomly assigned to either group by a coin toss
Allocation concealment (selection bias)	Unclear risk	Investigators enrolling participants could possibly foresee assignments given that the method used for assignment was based on a coin toss
Blinding of participants and personnel (performance bias) All outcomes	High risk	The type of intervention does not allow blinding of the personnel. However, authors reported that children were unaware of the method of preparation of cavities
Blinding of outcome assessment (detection bias) All outcomes	Unclear risk	Outcomes were evaluated by the investigator and by an "an independent evaluator" but no clear statement on the blinding procedure was provided
Incomplete outcome data (attrition bias) All outcomes	Unclear risk	1 out of 60 teeth in laser group was reassigned into the bur group because the child refused laser treatment. Of 32 recalled children, at 6 months' visit 4 children dropped out, and at 12 months' visit a further 8 children were lost to follow‐up
Selective reporting (reporting bias)	Unclear risk	The study protocol was not available. The primary outcome caries removal was reported in the methods but no data was provided
Other bias	Unclear risk	It was unclear whether the study was funded or not

Er,Cr:YSGG: erbium, chromium: yttrium‐scandium‐gallium‐garnet.
 Er:YAG: erbium‐doped yttrium aluminium garnet.
 Nd:YAG: neodymium‐doped yttrium aluminium garnet.
 SD: standard deviation.
 WHO: World Health Organization.