Those small grooves worn into teeth right at the gumline take two things acting together: acid softens the surface, then brushing wipes the softened layer away. Neither does much alone. Fix the acid and the timing, and brushing stops mattering nearly as much. Here's the plain-English version of what's happening — and the five changes that stop it.
Dentists call these non-carious cervical lesions — "non-carious" meaning they're not cavities, "cervical" meaning the neck of the tooth, where it meets the gum. That spot is the tooth's thinnest, weakest point. In our Keene and Joshua chairs these are among the most common findings in adults over 30, and almost everyone who has them has been told, at some point, that they "brush too hard." That's at most half the story.
Is it really from brushing too hard?
Here's the finding that reframes everything: in a controlled in-situ study, brushing abrasion on healthy enamel had no significant effect — acid erosion was what moved the needle. Brushing a hard, sound surface barely wears it; brushing a surface that acid has just softened removes material easily. "Brushing too hard" and "brushing after acid" turn out to be the same mechanism, and acid is the rate-limiting step. (Once the notch reaches the softer root surface underneath — dentin — both acid and abrasion matter, and progression speeds up. That's why acting early is worth it.)
Force does still play a role: patients with multiple recession sites brushed at nearly twice the pressure of those without (3.75 vs 2.12 newtons in one study) — and instruction alone doesn't reliably change force. What does is a pressure sensor. One more surprise: bristle softness is not the lever. At normal forces, soft vs medium bristles showed no difference in dentin wear, and in one lab test soft bristles caused more loss in root surface, likely by carrying more toothpaste slurry.
What about "abfraction" — is clenching causing my notches?
You may have read that bite forces flex the tooth and pop material off at the neck — the theory is called abfraction. Honest answer: the evidence is split, and the split is informative. A 2017 systematic review of 69 publications found 81% reported an association — but 38 of the 69 were laboratory or computer-model studies. A 2013 systematic review of the nine clinical studies concluded the evidence does not support the association — and explicitly does not support adjusting the bite to prevent or control these lesions. A cross-sectional clinical study found no significant relationship with bruxism, wear facets, or acidic diet; only age over 30 predicted the lesions. The lab evidence is strong, the clinical evidence is weak, and they measure different things. Practical translation: we don't grind on your bite to treat notches, and you should be skeptical of anyone who proposes it as the fix.
The five changes that actually stop them
1. Never brush right after anything acidic. Soda, juice, sports drinks, wine, citrus, vinegar, kombucha, sparkling water — wait at least 30 minutes. Brush before the acid, not after. 2. Rinse with plain water immediately instead — the single most useful habit here. 3. Switch to a verified low-abrasion toothpaste (RDA ≤ 70 once roots show). Whitening and tartar-control pastes are the harshest category — here's the RDA article with the only manufacturer-verified numbers. 4. Brush lighter, not softer — an electric brush with a pressure sensor is the most reliable fix, because it tells you when you're pressing too hard; being told to press lighter almost never works. 5. Stop scrubbing side to side — small circles or short gentle strokes angled toward the gum. And on drinks: how you drink matters more than what you drink. One soda sipped over two hours is far worse than the same soda in five minutes — your teeth sit in acid the whole time. Take acidic drinks with meals, use a straw, don't swish, follow with water.
Wear on the inside surfaces is a different story
Notches on the outer (cheek-side) surfaces point to diet acid plus brushing. Wear on the inner surfaces — the sides facing your tongue and palate — points to stomach acid, which is far stronger than anything you drink: reflux (including silent night-time reflux, common without any heartburn), or vomiting from any cause — pregnancy sickness, illness, migraines, medication. The location of the wear literally reads the cause, and both patterns in one mouth means two causes running at once.
If this is you, the most important step is medical, not dental: dental erosion is often the first visible sign of reflux and is frequently what gets it diagnosed — tell your physician what we found. Right after any episode of reflux or vomiting: do not brush. Rinse immediately with water — better, a teaspoon of baking soda in a cup of water — and wait at least 30 minutes. And one more thing, said plainly: for some people, vomiting is connected to difficult feelings about eating, weight, or control. It's more common than most people realize, it's treatable, and nobody here is judging you. If you'd rather start outside a dental office, the National Alliance for Eating Disorders runs a free helpline staffed by licensed clinicians: 1-866-662-1235.
What this means for you
Change the timing this week — water rinse after acid, 30-minute wait, brush before acidic breakfasts, and a pressure-sensor electric brush if you're a known scrubber. Then let us look: we'll tell you whether the pattern reads diet, stomach acid, or both, whether the notch has reached dentin, and whether a filling makes sense yet. (Fillings at the gumline are known to be hard to keep in place — if one comes loose, that's expected, not a mistake, and we'd rather see it early.) The toothpaste half of the fix is in the label guide, and if your mouth is also dry — which multiplies all of this — start with the dry-mouth article.
Frequently asked questions
Can gumline notches repair themselves?
No — enamel doesn't grow back, and neither does lost root surface. What you can do is stop progression, which the acid-timing habits genuinely achieve, and desensitize or restore where needed. Shallow, symptom-free notches are often just monitored; deepening or sensitive ones we discuss filling.
Do I need a night guard for my notches?
Not for the notches. Clinical systematic-review evidence doesn't support bite forces as the driver or bite adjustment as treatment. A night guard may still be right for you for other reasons — tooth wear on chewing surfaces, jaw symptoms, cracked teeth — but we'd recommend it on those grounds, honestly, not as a notch cure.
Why does cold hurt at my gumline?
The notch has usually reached dentin — the root layer under the enamel — which contains microscopic tubes running toward the nerve. Cold, sweet, and touch travel down them. Low-abrasion pastes, stannous-fluoride sensitivity pastes, fluoride varnish in the chair, or a small filling each close those tubes to a different degree.
Should I stop using whitening toothpaste if I have recession?
Yes — that's the one category we'd have every recession patient drop. Whitening and tartar-control formulas run roughly RDA 100–200, the harshest range on the shelf, and once roots are exposed abrasiveness stops being a footnote and becomes the main variable.
Educational content, not a substitute for an examination. Study figures as cited; formulations change — verify current labelling.
Point at the notch at your next cleaning and we'll read the pattern with you. Keene · Joshua · (817) 476-4537.