Don't hurry through if it will hurt your grades. If you can't keep a competitive GPA with the courseload, I think you should take fewer classes. The matriculating stats for dental school are going up every year. You don't want to endager your chances of even getting in. 🙂
Although, if it's just a matter of a 3.8 semester instead of a 4.0 - well... then maybe you should just rush.
Remember some specialties consider your undergrad grades as well. Especially oral surgery; don't burn any bridges. 🙂
I agree with supernumerary. Whatevery you do keep your GPA up. Don't worry about dental school yet, for that will just come later when you work hard in school. Yes, average GPA is just going up each year for dental school which means it's just getting competitive, so don't compromise your GPA at the expense of "getting used to the workload". Good luck to you!