" We use the OMSAS scale when calculating cumulative GPA for applicants. The GPA conversion table can be found on our website at: https://www.dentistry.utoronto.ca/how-to-apply/application-page. All university courses are included in the calculation of your cumulative GPA including summer courses, graduate courses and online university courses. If you have completed four years of university or more we will drop your one lowest year only when calculating your GPA provided it is not your most recently completed year. We consider one academic year to be all the courses taken from September to the end of August. " - UoT website
Essentially you should just focus on finishing your 4 years and aim to get around a 3.94+. If they say they'll take off your worst year then they will; don't be paranoid about it.