Study	Reason for exclusion
Andjelic 1991	Not RCT. Control group selected from another village
Aslanova 2003	Parallel group study comparing different sealant materials to control without sealant. Not RCT. Random allocation not stated
Azul 1990	Study comparing resin‐based sealant to control without sealant. Not RCT. Random or quasi‐random allocation not stated.
Baglioni‐Gouvea 2001	Conference abstract with split‐mouth study comparing resin sealant to compomer. Comparison excluded in this update. No random or quasi‐random allocation to surfaces within each tooth pair (teeth 26 and 46 were sealed with Fluoroshield, and teeth 16 and 36 with Compoglass).
Beiruti 2006	Quasi‐randomised parallel group study comparing glass ionomer sealant with resin‐based sealant. Quasi‐randomised parallel group designs excluded in this update. (Children were randomly allocated to one of the two sealant treatment groups using the class list. The first child on the list was allocated to the composite resin and the second child to the glass ionomer group and so on. Which treatment group to start with was determined through the flip of a coin.The sequence generation included systematic, non‐random component (class lists)).
Boksman 1987	Split‐mouth study comparing glass ionomer with resin‐based sealant. No random allocation to surfaces within each tooth pair (teeth on the left side of the mouth sealed with a glass ionomer cement, teeth on the right side with resin).
Braga 2009	RCT comparing three treatments: silver diamine fluoride; glass ionomer sealant; and cross toothbrushing technique. Each of these three treatments was used in each child's mouth. Study design neither parallel group nor split‐mouth (however, data analysed as in parallel group designs).
Carlsson 1992	Study mainly intended to estimate the number of Mutans streptococci in saliva after treatment with sealants. Not RCT. Random allocation not stated. Primary teeth included in study.
Carlsson 1997	Parallel group design comparing resin‐based sealant (children at caries risk) with reference group without sealant (children at low caries risk), not randomised. Randomised split‐mouth design within the sealant group comparing two resin‐based sealant materials.
Centenaro 2001	Conference abstract with split‐mouth study comparing resin sealant to glass ionomer. No random or quasi‐random allocation to surfaces within each tooth pair (teeth 16 and 36 were sealed with Fluoroshield, and teeth 26 and 46 with glass ionomer).
De Puel 1983	Split‐mouth design comparing resin‐based sealant to control without sealant. Not RCT. Random or quasi‐random allocation not stated.
Dogon 1995	Conference abstract. Not RCT. Random allocation not stated. Children were divided into five groups by classroom.
Duggan 1987	Test material was a varnish.
Flório 2001	RCT. Three groups: sealant, fluoride varnish and control. Conventional control group was not used; control group children got other preventive treatments than sealants (e.g. fluoride flasks were given to home).
Güngör 2004	RCT study comparing polyacid‐modified resin composite with resin‐based sealant. Comparison excluded in this update.
Helle 1975	Study design comparing resin‐based sealant materials to control without sealant including both permanent and primary teeth (majority of the sealed teeth were sealed by Nuva‐Seal material). Not RCT. Random or quasi‐random allocation not stated.
Hepp 1990	Not RCT. The author was contacted to clarify this.
Hickel 1989	Split‐mouth design comparing glass ionomer to resin‐based sealant. Not RCT. Random or quasi‐random allocation not stated.
Hilgert 2015	Trial comparing three treatments: daily supervised toothbrushing at school, resin‐based sealant and glass ionomer sealant. Not RCT related to comparison of glass ionomer with resin sealant which was the only relevant comparison for this review (randomised only related to comparison of glass ionomer sealant with toothbrushing; schools with equipped with a dental unit were allocated to resin‐based sealant group)
Hotz 1978	Split‐mouth design comparing resin‐based sealant to control without sealant. Study included other preventive treatment (Elmex Fluid around 10,000 ppm F 6 times per year). The author was contacted to clarify this.
Irmisch 1992	Not RCT. Random or quasi‐random allocation not stated.
Jodkowska 1984	Split‐mouth study (resin versus no treatment). Randomisation unclear.
Jodkowska 2008	Resin‐based sealant versus control without sealant comparison. In total four groups: children were divided into three groups depending on the number and type of teeth to be sealed; the fourth group was a control group. Group 1: two first molars sealed (one maxillary and one mandibular) with the remaining two left as controls. Group 2: all four first molars sealed. Group 3: all molars and premolars sealed as they erupted. Group 4: control group, no teeth sealed. Three resin‐based sealant materials used (one of those materials was Nuva‐Seal). The quote "Teeth designed for sealing were allotted at random to be sealed with 1 of the materials used" gives an impression that the sealant material for each tooth to be sealed was randomised (but not the tooth or teeth). Allocation of children to groups not randomised. Group 1 could have been handled as split‐mouth design but the selection of teeth to be sealed in each child's mouth remains unclear. Further, Nuva‐Seal was used as sealant material. Study included other preventive treatment (NaF‐rinsing 5 times during the year at 2‐week intervals).
Kamala 2008	Children randomised to two glass ionomer groups, and for each child split‐mouth design was used (the other tooth of the tooth pair was sealed with one of the two glass ionomer materials and the contralateral tooth was left unsealed as control). Randomisation at tooth pair level not stated. It remains unclear how the tooth within a tooth pair to be sealed was selected.
Kawakami 1984	Not RCT. Random or quasi‐random allocation not stated.
Komatsu 1994	Parallel group study comparing glass ionomer to control without sealant. Not RCT (control group was selected using annual school examination records).
Lampa 2004	RCT study comparing polyacid‐modified resin composite with resin‐based sealant. Comparison excluded in this update.
Li 2008	Glass ionomer sealant versus control without sealant. Unclear data: (1) contradictory results in table and text, (2) drop‐out rates not specified by group. Additional information was inquired from the authors to assess the adequacy of the study for this review (no response).
Liu 2000	Conference abstract with split‐mouth study comparing resin‐modified glass ionomer to resin sealant. Not RCT. Random or quasi‐random allocation not stated.
Louw 2002	Conference abstract of RCT comparing glass ionomer to control without sealant on erupting teeth. No full‐text report available (the author was contacted to clarify this).
Lovadino 1994	Split‐mouth design comparing glass ionomer to resin‐based sealant. Not RCT. Random or quasi‐random allocation not stated.
Lusanandana 1986	Not RCT. Random or quasi‐random allocation not stated.
Madléna 1993	Study comparing resin‐based sealant to no treatment. Not RCT. Random allocation not stated (translator‐based information)
Manau 1989	Study comparing resin‐based sealant to no treatment. Children received other preventive treatments (fluoride mouthrinses).
Marković 2012	Glass ionomer sealant versus resin sealant comparison. Unclear data, no information e.g. on: (1) the numbers of teeth under evaluation at baseline in each group, (2) drop‐out rate of children at follow‐up. Additional information was inquired from the authors to assess the adequacy of the study for this review (no response).
Mejàre 1990	Study comparing glass ionomer to resin‐based sealant materials. Not RCT. Random or quasi‐random allocation not stated. Study design neither parallel group nor split‐mouth design with tooth pairs.
Mel'nichenko 1994	Split‐mouth study comparing sealant to control without sealant. No random allocation to surfaces within each tooth pair (right side of each subject control side, and left side sealant side).
Monse 2012	Only the 3 schools without daily toothbrushing program at school could be considered in this review but there were too few clusters for adequate RCT design
Morgan 1998	Study included other preventive treatment (weekly 0.2% NaF‐rinsing).
Morrow 1997	Conference abstract of a randomised study comparing four different sealant materials. No information on numbers of children or numbers of teeth per child in each group at baseline. No information on data at follow‐up in numbers (only in percentages). No contact details of the authors.
Noack 1997	Conference abstract with split‐mouth study comparing compomer to resin sealant. Comparison excluded in this update. Random or quasi‐random allocation to surfaces within each tooth pair not stated.
Oba 2009	RCT comparing glass ionomer to resin‐based sealant. The design stated to be a split‐mouth. However, the number of sealed teeth with each material was different at baseline (91 in glass ionomer cement group and 116 in resin group). The report gives an impression that both materials were used in one child's mouth which has, however, not been taken into account in the analyses. Additional information was inquired from the authors to assess the adequacy of the study for this review (no response).
Ohmori 1976	Not RCT. Split‐mouth study and right side of each subject was the test side.
Oliveira 2008	Study comparing glass ionomer cement with a resin‐based sealant with or without an associated bonding agent (six groups). Not RCT. No random allocation to groups.
Pereira 1999	RCT comparing two glass ionomers to control without sealant. Data remain unclear; some contradictory data in separate reports for the same follow‐ups.
Petrovic 1996	Conference abstract of a study comparing four different sealant materials. Not RCT. Random or quasi‐random allocation not stated.
Poulsen 1979	Study included other preventive treatment (fortnightly fluoride rinses).
Poulsen 2006	Split‐mouth study comparing resin‐based sealant to glass ionomer. Very different follow‐up periods for tooth pairs.
Prados‐Atienza 2002	Assignment to the sealant group was not randomised.
Puppin‐Rontani 2006	Split‐mouth study comparing resin‐based sealant to compomer. Comparison excluded in this update. No random or quasi‐random allocation to surfaces within each tooth pair.
Rajić 2000	Split‐mouth design comparing sealant to control without sealant. Not RCT. Random or quasi‐random allocation not stated.
Simonsen 1980	Not RCT. Study comparing resin‐based sealant to control (sealant group was a random sample; the control group of children was selected). Matched pair analysis was performed.
Skrinjaric 2008	Split‐mouth study (glass ionomer versus resin). Study mainly designed to investigate retention rate of glass ionomer cement heated during setting time. No random allocation to surfaces within each tooth pair (teeth on the left side of the mouth sealed with a glass ionomer cement, teeth on the right side with resin).
Smales 1996	Study comparing resin‐modified glass ionomer to resin sealant. Intra‐individual study design not clearly split‐mouth design with tooth pairs. Patients older than 20 years. Follow‐up time 6 months.
Taifour 2003	Study design comparing glass ionomer to control without sealant. Not RCT. Erupted teeth were sealed and non‐erupted, later erupted teeth were used as controls.
Tanguy 1984	Not RCT. Random or quasi‐random allocation not stated.
Tapias Ledesma 2002	Study comparing sealant with control without sealant. Not RCT (prospective cohort study). Sealant group with other preventive treatments.
Thylstrup 1976	Split‐mouth design comparing resin‐based sealant with control without sealant. Study included other preventive treatments (e.g. fortnightly 0.2% NaF‐rinsing).
Tostes 1997	RCT with three treatments (glass ionomer sealant, resin‐based sealant, and fluoride varnish). Three of each child's teeth were divided to receive one of those treatments; the fourth tooth was left as a control without treatment (in total there were 25 children with 100 teeth). Data reported as summary data for each treatment. Study design not suitable for reliable data analysis (the data could have been treated as a split‐mouth design if they could have been reduced to two treatments which was not the case in this study).
Unal 2015	No data on dentine carious lesions (the trial was designed to evalute the remineralizing capacity of sealants used with or without gaseous ozone; outcome measured by means of changes in the DIAGNOdent values)
Valsecki 1992	Conference abstract. Not RCT. Random or quasi‐random allocation not stated.
Vieira 2000	Conference abstract of a trial comparing glass ionomer to resin‐based sealant. No full‐text report available (the author was contacted to clarify this but the information was not available for this update).
Vrbic 1983	Split‐mouth study, random or quasi‐random allocation to surfaces within each tooth pair not stated.
Winkler 1996	Split‐mouth study comparing resin‐modified glass ionomer to resin‐based sealant. Not RCT. Random or quasi‐random allocation not stated.
Wåhlin 1997	Parallel group design comparing sealing with no sealing, not randomised. The randomised design comparing glass ionomer cement with resin‐based sealant not clear split‐mouth design with tooth pairs. Very different follow‐up periods (in average 4.3 years; range 2 to 5 years).
Yakut 2006	Split‐mouth study comparing resin composite with polyacid‐modified resin composite. Comparison excluded in this update. Not RCT. Random or quasi‐random allocation not stated.
Yildiz 2004	Split‐mouth study comparing resin‐based sealants to control without sealant. Not RCT. Right side in each patient's mouth was the test side, and left side was the control side.
Yilmaz 2010	RCT comparing different sealant materials: two BIS‐GMA resin sealants, ormocer, and compomer. Caries data remain unclear. There are unexplained missing data in all groups at both follow‐ups (e.g. results for 34 teeth are missing at 24 months).
Yoshihara 2000	Study comparing glass ionomer cement to resin‐based sealant. Not RCT. Random or quasi‐random allocation not stated.
Zhang 2003	Split‐mouth study comparing sealant with no treatment. Not RCT. Random or quasi‐random allocation not stated.
Zimmer 2009	Split‐mouth study comparing glass ionomer to resin‐based sealant. Not RCT. Random or quasi‐random allocation not stated. Very different follow‐up periods for tooth pairs (range 1.5 to 4.1 years).

RCT = randomised controlled trial.