Start with the recommendation: soft is the safest default
For most people, soft bristles are the right starting point. The American Dental Association recommends a soft-bristled toothbrush because it can remove plaque effectively while reducing the risk of unnecessary abrasion to the gums.
That does not mean every soft brush feels the same, or that "soft" by itself tells you whether a head is well designed. Filament diameter, length, density, tuft layout, head size, end-rounding, and the motion of a powered brush all influence how a toothbrush feels and performs.
Why medium can feel cleaner - even when that is not the whole story
A firmer bristle creates more resistance against the tooth. That sensation can feel satisfying, which makes it easy to equate intensity with cleaning. But brushing is not a scrubbing contest. Plaque removal depends on contact, coverage, time, technique, and consistency - not simply on using the stiffest filament you can tolerate.
This is particularly important with an electric toothbrush. The motor is already providing motion. Pressing harder can flatten the bristles and make the experience harsher without necessarily improving the result.
A brush head is a system, not a single firmness
One of the things we learned while developing Lyric is how incomplete the soft-versus-medium question can be. We tested multiple bristle configurations. Some felt comfortable but did not give us the cleaning experience we wanted. Others felt more assertive but were less pleasant around the gumline.
Lyric ultimately uses a dual-density layout. The outer bristles are very soft and are positioned to keep contact around the gums comfortable. The center bristles are firmer, giving the middle of the head a more substantial cleaning feel. The head itself is deliberately not oversized or bulky, so it remains easy to move around the mouth.
We also specifically requested rounded filament ends as part of the brush-head specification, including an approximately 80% end-rounding target. That detail is not there to create a marketing number; it reflects the same design goal as the rest of the head: effective contact without turning two minutes of brushing into an unnecessarily aggressive experience.
“We did not want to choose between a head that felt gentle and one that felt capable. The goal was the balance, not the label.”
Comfort is not a secondary feature
Performance was our first priority when developing Lyric, but we define performance more broadly than "the strongest possible clean, regardless of how it feels." A toothbrush is used twice a day, every day. If it feels bulky, harsh, noisy, or unpleasant, that experience matters because it affects how willingly and consistently you use it.
Our aim was to find the best balance we could between cleaning performance and a brush people would genuinely enjoy using. That took more than choosing a bristle firmness from a catalog. It meant testing combinations until the head felt gentle where it should and purposeful where it needed to.
If you have sensitive teeth or gums
If your gums are sore after brushing, you have recession, persistent sensitivity, recent dental work, or a history of brushing-related abrasion, do not use a firmer brush as a way to chase a stronger clean. Use gentle pressure and ask your dentist or hygienist what is appropriate for your mouth.
Sensitivity can have many causes, and changing bristles is not a substitute for having persistent discomfort evaluated.
The short version
For most people, soft bristles are the sensible default. But do not assume a one-word firmness label tells the whole story. The best brush head combines comfortable contact, thoughtful geometry, good technique, and a design that makes it easy to brush thoroughly for the full two minutes.
Sources
American Dental Association: Toothbrushes
MouthHealthy: Brushing Your Teeth
Editorial note: General oral-care information only; individual needs can vary. Readers with persistent pain, bleeding, sensitivity, or other dental concerns should speak with a dentist or qualified dental professional.
