Flossing Triangles: Why Gaps Show Up

You started flossing or had a cleaning, and now small triangles between your teeth suddenly look obvious. That change is real, but flossing usually did not create a new gap overnight.

Those spaces often become visible when swollen gums shrink back down or when tartar that was filling the area is removed. Existing gum recession, tooth shape, and bone support can also make the triangle easier to see.

Flossing triangles are open spaces near the gums

Flossing triangles are the little open spaces between two teeth near the gumline. They can look dark because the mouth behind them shows through, which is why people often call them black triangles after flossing.

A healthy gum papilla is the small wedge of gum that normally fills that space. When that tissue is shorter than it used to be, or the teeth are shaped in a way that leaves more room, the triangle becomes visible.

Flossing usually reveals the space rather than causing it

Flossing does not usually create a gap between teeth. The more common pattern is that plaque and tartar were sitting there, the gums were puffy from irritation, and the space looked filled until the inflammation settled or the buildup came off.

People are often shocked because the change seems sudden. The tissue change may have been developing for a long time, and the first week of better cleaning is simply when the area starts to look more honest.

They got them because they weren’t flossing. Plaque used to be in place of those triangles..the more the plaque the further it pushes the gums away. Then your friend started flossing..and they could now see the gaps left behind..

— r/askdentists

Spaces often show after tartar removal for the same reason

Gaps between teeth after cleaning are common when tartar had been packed around the teeth. Tartar can act like a false wall, so once it is removed, the true shape of the teeth and gums is easier to see.

Home care can remove soft plaque, but hard tartar needs a professional cleaning. If a new space showed up right after scaling, the cleaning probably exposed a space that was already there rather than carving one out.

The way to approach this is to go in for the professional cleaning and then see if it settles down. There isn’t anything else you can do at home other than keep up with brushing and flossing, but that won’t get rid of the longstanding established buildup on your teeth which is likely contributing to the issue.

— r/askdentists

Gums may improve, but full regrowth is less predictable

Bleeding and puffiness often improve when flossing becomes consistent. That part is routine: less plaque between the teeth usually means less irritation, so gums can look firmer and less swollen over time.

Full regrowth of a missing gum papilla is less predictable. If the triangle is mostly from temporary inflammation going down, the look may soften a bit; if it is tied to recession, bone loss, tooth shape, or tooth movement, home care alone usually does not rebuild that tissue.

Also, if you floss regularly you will discover that your gums won't bleed anymore while flossing. I think that is a really good signal showing that your mouth's health is better when you floss.

— r/LifeProTips

People often blame the floss when the technique or timing is the issue

People often assume the floss cut the gums and made the space. Rough snapping can irritate the gum edge, but that is different from creating a lasting triangle between teeth.

The usual goal is to slide the floss gently under the contact point and hug one tooth, then the other, so the sides of both teeth get cleaned. That removes the sticky bacterial film a toothbrush misses between teeth.

• Guide the floss through the contact instead of popping it hard into the gums.
• Curve the floss into a C shape against one tooth, then the neighboring tooth.
• Use a clean section as you move around the mouth.
• If floss is too awkward, another between-teeth cleaner may be easier to do consistently.

That metaphor is ambiguous becuase I could as well say, that brushing my teeth is cleaning them (freeing them from the bigger junk) and then doing the finer cleaning with the floss. My dentist says flossing is less for bigger things stuck between your teeth but to remove the always existent film of bacteria building everywhere but can't be removed by toothbrush between the teeth.

— r/LifeProTips

Some triangles need an exam, not better guessing

Some black triangles after flossing are mainly about gum swelling going down, but not all of them are. Tooth alignment, triangular tooth shape, previous orthodontic movement, recession, and bone loss can all leave a visible space even when home care is good.

A dentist should look at a triangle that is new, getting larger, trapping food, or coming with loose teeth, pus, or ongoing bleeding. That is the plain way to tell whether you are seeing normal healing after better cleaning or a gum problem that needs attention.

I have to because of the huge gaps Invisalign created between my teeth. Food gets stuck and it can be painful. When I can't be bothered flossing or if I'm out and about I use interdental brushes. They're less hassle.

— r/Invisalign

Common questions

Will flossing create gaps between my teeth?

Usually no. Flossing more often tends to uncover spaces that were masked by puffiness, plaque, or tartar, not manufacture a brand-new gap. Aggressive snapping can irritate the gums, but that is not the usual cause of a lasting triangle.

Why do black triangles show up after I start flossing?

Black triangles after flossing usually become noticeable when inflamed gums shrink back to a less swollen shape. The dark color is often just the shadow of the space behind the teeth. Existing recession or tooth shape can make the change more obvious.

Why do spaces show after tartar removal?

Tartar can fill in the area near the gumline and hide the true contour of the teeth. After a cleaning removes that buildup, the space that was already there becomes visible. The cleaning exposed the shape; it did not usually create it.

Will my gums grow back and fill the triangle?

Bleeding and swelling can improve with steady brushing and flossing, so the area may look a bit better if inflammation was part of the problem. Complete fill-in is much less predictable when the tissue has receded or the bone support is lower. Tooth shape and alignment also affect whether the papilla can fully occupy the space.

Why do gaps between teeth seem bigger after cleaning?

The teeth can feel smoother and the gums can look less puffy after a cleaning, so the spaces are easier to notice. If heavy buildup was present before, the difference can seem dramatic. Food trapping after that change is common and worth mentioning at your next visit.

Start with gentle daily cleaning between the teeth for a few weeks, not harder scrubbing. Watch for less bleeding and less puffiness, because those are the changes that usually show your routine is helping.

If the triangle appeared after a cleaning, assume the space was uncovered, not carved out. If the area keeps enlarging, traps food badly, or bleeds despite steady care, book a dental exam and get a clear explanation of what is causing that specific gap.