This retrospective study’s aim was to examine the success rate of prepared and unprepared sealants at different ages of placement, and to determine if caries risk played a role in the sealants’ success. Data was collected from 1,173 first molars subjects from a private pediatric dental clinic (Children’s Dental World, Winnipeg, Manitoba). These were categorized based on initial treatment types (unprepared sealants (55%), prepared sealants (38%), and non-treated (7%)), and then further analyzed by their initial caries risk (low (27%) or moderate-high (73%)). Treatment failure and success were assessed at 12-months and 24-months post-treatment. Overall, in a 24-month period, both sealant methods were found to be highly successful with an overall average of 97% at 12-months and 93% at 24-months. The prepared sealants method statistically did not have significantly more failures (3.24% and 4.31%) than unprepared sealants (3.67% and 2.71%) at both recall periods. There were more failures for the sealants when placed at age 5, 6, and 7 years (5.54% and 5.88%) at 12-months and 24-months. Initial and change in caries risk status did not seem to have an impact on the overall success rate of sealants. The highest success rate for sealed molars was found when subjects consistently remained at low caries risk over the 24-month period (Group 1 97.60%) but it was found to be statistically insignificant. Overall, both sealant methods are highly successful in preventing occlusal caries on first permanent molars, regardless of caries risk. / October 2015