Flossing the back molars is often challenging due to their position and the limited space at the back of the mouth, yet these teeth are highly susceptible to plaque buildup. Molars have wider surfaces with grooves and pits designed for chewing, which easily trap food particles and bacteria that a toothbrush cannot reach. Neglecting these posterior teeth means skipping a large portion of your mouth’s surface, as flossing accounts for cleaning up to 40% of the tooth area missed by brushing. A specialized technique is necessary to ensure these hard-to-access areas receive a thorough and effective cleaning.
Preparing for Effective Flossing
Dental professionals commonly recommend starting with a length of string floss measuring about 18 inches. This length allows you to use a fresh segment of floss for each interdental space, preventing the transfer of plaque and bacteria.
Once the floss is measured, wind most of it around the middle or ring finger of one hand, and a small amount around the middle or ring finger of the opposite hand. This leaves a short working section of only one to two inches of taut floss pinched between the index fingers and thumbs for maximum control and maneuverability. Using a mirror can help guide your hands, especially when reaching the lingual (tongue) side of the lower molars, where visibility is lowest.
Step-by-Step Guide for String Floss
To guide the floss between the molars, use a gentle, controlled back-and-forth “sawing” motion to ease it through the contact point. Avoid forcefully snapping the floss down, which can injure the delicate gum tissue. Once the floss has passed the contact point, curve it tightly around the side of one molar, forming a “C-shape” that hugs the tooth’s contour.
Slide the floss gently into the sulcus (the small pocket between the tooth and the gum) until you feel slight resistance. While maintaining the C-shape, move the floss up and down the side of the tooth several times, using a “shoe-shining” motion to scrape away plaque. This motion must cover the entire side of the tooth, from the gum line to the top of the tooth, polishing the surface clean.
After cleaning the first tooth surface, keep the floss in place and reposition the C-shape to hug the adjacent molar, repeating the up-and-down scraping motion. To clean the very back surface of the last molar, curve the floss around the entire back of the tooth, ensuring it cleans the distal surface. Unwind a clean section of floss from one finger and wind the used section onto the other before moving to the next interdental space.
Specialized Tools for Difficult Access
For individuals who experience difficulty with manual dexterity or a strong gag reflex when using string floss, alternative tools can provide an effective clean for back molars. Floss picks, particularly those with a Y-shaped design, offer a more rigid handle and angle that simplifies reaching the far back teeth. The handle angle allows for better leverage and control in the posterior regions.
Water flossers (oral irrigators) use a pressurized stream of water to remove plaque and food debris from between teeth and below the gum line. This pulsed water action is highly effective for cleaning around molars and is a suitable option for those who struggle with traditional flossing. Interdental brushes, which resemble small pipe cleaners, are also useful for cleaning the wider gaps that sometimes exist between molars.
Ensuring Complete Coverage and Avoiding Mistakes
A common mistake that reduces flossing efficacy is failing to curve the floss around both teeth in the space. Simply sliding the floss straight up and down only cleans a small portion of the surface, leaving plaque on the remainder of the sides of both molars. The C-shape technique is necessary to wrap the floss around the convex surface of each tooth, ensuring a thorough clean of the entire interproximal area.
Another oversight is failing to guide the floss slightly below the gum line, where bacteria and sticky biofilm often accumulate. While it is important to avoid snapping the floss aggressively, a gentle slide below the gum line is necessary to dislodge trapped debris. If bleeding occurs, it is often a sign of inflammation from not flossing regularly, and consistency is necessary to improve gum health. Remember to use a fresh section of floss for each new area, preventing the spread of bacteria.