I'll give a different opinion here. I took biochem as an undergrad and it has definitely helped me in dental school. It is not that biochem is hard in dental school... but when you have 7 other classes (like Anatomy, Histology, etc.) to study for, biochem can be tough. I re-learned all the enzymes, structures, and controls of glycolysis/Kreb cycle in about 2 hours, while my classmates who hadn't taken biochem must have spent several hours. This allowed me to spend that extra time on other classes (Anatomy and Histology) and that was a relief.
As long as your biochem course focuses on human metabolism (as opposed to plants and lots of theoretical stuff), it should help you. But that's just my opinion.