Each tooth has five surfaces - the front, back, side facing the cheek, side facing the tongue and the top.
A toothbrush can reach the front, back and top of the tooth, but its bristles are not thin enough to get between the teeth, said Dr. Jeff Porter, whose private practice is at 329 Maynard St.
"That's 60 percent," he said. "Flossing often reaches the other 40 percent."
Brushing and flossing results in healthy teeth, but that doesn't mean everyone does it.
"It's silly to just say 'brush and floss,' " Porter said. "You don't do it because the dentist and hygienist tell you to ... It's because (you) want good health and oral health."
The technique for brushing is what he calls the "jiggle sweep."
Holding a toothbrush at a 45-degree angle is the best way to reach the hollows where plaque can hide.
"The jiggle part creates friction," Porter said. "Friction loosens sticky plaque."
Once the plaque is loosened, it can be swept away, similar to sweeping the floors.
Porter pointed to a corner on the floor. "There is the hollow," he said. "You jiggle to get the dirt loose and sweep it away. We want gum, I call it, stimulation."
Two aspects of flossing are very useful for preventing diseases, Porter said.
The first step is to floss between the teeth, past where the teeth connect toward the gum because plaque connects there.
"Big areas for tooth decay are between the teeth," Porter said. "For kids, it's the biting service and between the teeth."
The second step for flossing is "C-shaping."
When regularly flossing, the floss is held on a straight line. With the C-shape, Porter recommends taking the straight line to get between the teeth and turn it into a C-shape by hugging the side of the root wall.
The jiggle sweep done for brushing also can be done while flossing.
While using the C-shaping technique, jiggling the floss slightly will create friction to loosen the plaque which can be swept away vertically.
"You're doing the same thing," Porter said, "using different tools."