Black triangles between teeth: what to ask a dentist

Black triangles are small dark spaces near the gumline between your teeth. Learn what causes them and what questions to ask your dentist.

Medically reviewed by Dr. Jose, DDS — August 31, 2026

What are black triangles between teeth?

Black triangles are small dark spaces that appear near the gumline between your teeth. The space is usually visible when you smile or look in a mirror. The “black” appearance happens because light doesn’t reflect well into that narrow gap—it’s not mold or decay, just a shadow.

Common reasons black triangles form

Several factors can create these spaces:

Gum recession. When gum tissue pulls back from the tooth, the root becomes exposed. If this happens on neighboring teeth, a triangular gap appears. This can result from aggressive brushing, gum disease, or natural aging.

Gum disease. Advanced gum disease can destroy the bone and tissue that normally fills the space between teeth, leaving a gap.

Tooth shape and spacing. Some people naturally have teeth with pointed or narrow crowns, or wider spacing. As gums recede slightly over time, these shapes can make gaps more obvious.

Bone loss. When underlying bone shrinks (from disease, trauma, or other causes), the gum follows, creating space below the contact point of the teeth.

Prior orthodontic treatment or natural shifting. If teeth have moved slightly over years, the gum and bone may not fill the new space completely.

Questions to ask your dentist

Bring these questions to your next visit:

• “Why do I have these spaces?” Ask your dentist to show you on your x-rays or in a mirror. Understanding the cause shapes next steps.
• “Is gum recession involved?” If yes, ask whether it’s stable or changing. Discuss what may have caused it (brushing technique, gum disease, age, genetics).
• “How should I clean this area?” Aggressive brushing can worsen recession. Your dentist or hygienist can show you a gentler technique and recommend tools.
• “Are my gums and bone healthy?” Request a gum-health assessment. If disease is present, early treatment matters.
• “What options do I have?” Ask what your dentist recommends—whether it’s monitoring, improved hygiene, a graft, bonding, or another approach—and why.
• “Can I see my x-rays?” Understanding what the images show helps you track changes and make informed decisions.

What you can do now

Practice gentle oral hygiene. Brush with a soft-bristled toothbrush using gentle, circular motions. Aggressive scrubbing can accelerate gum recession.

Floss or use interdental cleaning. Keeping the space between teeth clean reduces inflammation and helps you notice any changes.

Avoid tobacco and limit alcohol. Both slow gum healing and worsen gum disease.

Stay hydrated and manage stress. Both support overall gum health.

Schedule regular dental visits. Early detection of gum changes makes management easier.

Related concerns

If you also notice tooth chipping or gaps elsewhere in your mouth, ask your dentist about those too. Sometimes multiple changes suggest a common cause worth addressing. See our guides on gum recession causes and dental bonding for chips and gaps for more detail.

How MediMouth helps

If you don’t have a regular dentist, MediMouth can help you find one in Arizona. Bring these questions to your first visit, ask to see your x-rays and gum health assessment, and discuss what’s best for your situation. A dentist who listens and explains your options empowers you to make choices that fit your goals.

This guide is educational information from MediMouth. It is not a diagnosis or a treatment plan, and it isn't a substitute for seeing a licensed dentist.