Foreword: Please beware that I ask this question only for mouthwash with NO alcohol whatsoever; so please omit alcoholic mouthwashes (which can cause cancer).

Since my grandmother continues to develop cavities, she twice daily brushes, flosses, then flosses again with interdental brushes, and concludes with a Crest mouthwash with 0 alcohol (see the footnote). She also abstains from any added sugar or sweeteners.

Question 1: How does saltwater compare with non-alcoholic mouthwash for daily lifelong use? Her dentist does not know of any relevant research, and only recommends saltwater for short-term use. So her dentist agrees with some of the claims here by Dentist David Kerr (B.DSc (Hons) BSc (Hons), University of Queensland).
Question 2: But is Dentist Kerr perfectly right in his criticism (of saltwater) below?

How about using salt water long term?

Longer term, the salt water is acidic, so there would be a problem if you were to use it every day, it could erode the teeth, but is not necessarily abrasive to the teeth. It is the acidity of the salt water that could eat away and soften the enamel on the teeth making them more susceptible to wearing, chipping and cavities.

Footnote: My grandmother uses this brand because it contains cetylpyridinium chloride, which (this website claims) has 'been proven to reduce plaque or fight cavities'.

  • "Is Dentist Kerr perfectly right...?" It is unlikely that he is perfectly right. Your grandmother needs to see a new dentist. It is not unusual for the elderly to have poor oral health as a result of medications or medical problems as well as decreased salivary flow. If her dentist cannot advise her adequately, she needs to find a better one. – anongoodnurse Apr 28 '15 at 3:59
  • 1
    For starters, Dentist Kerr is incorrect that salt water is acidic, so that's not an encouraging sign. Sea water, which is probably a good analogue for home brewed salt water, is actually slightly base. – Carey Gregory Aug 11 '15 at 2:13

Comparing "saltwater" to non-alcoholic mouthwash may be too general.

If I remember correctly, pH is dependent on OH- (hydroxide) and H+ (Hydrogen) levels. Depending on the type of salt, let's say NaCl (table salt), water will recombine with the salt, but OH and H levels aren't affected. Na binds to OH and H binds to CL in equal quantity.

Regarding the following that I found below, I believe "alkalinize" can't be taken to mean below neutral. I think it means that it lowers the pH level, whether to basic or less acidic. How I think of it is that you start with a highly acidic environment due to the bacteria. Then you use something with less acidity to average out the pH.

"Salt water rinses are good because they alkalinize the mouth (opposite of acidify, which is what the bacteria create.) Use one-half teaspoon each of baking soda and salt in a cup of warm water. The alkalinity helps decrease the bacteria count because they like an acid environment. As far as hot or cold, I'm not sure it matters. The rise in pH (alkalinity) is temporary. That is why the docs are promoting the Peridex, because they last longer."1

However, I believe that the acidity is relative. So for short term, it kills the bacteria, but for long term I believe Dr. Kerr is correct: it erodes teeth, which are made from Ca+ and probably fall to influence of the Cl- present in the solution.

Cetylpyridinium chloride is a modern anti-sceptic. Despite the hazards of LARGE quantity exposure, "CPC was one of only three antimicrobial systems to be classified as safe and efficacious for the treatment of plaque-induced gingivitis, along with stannous fluoride and essential oils."2 So it's safe in the amounts we use. Plus, hopefully you're not swallowing your mouthwash.

1: Ped-Onc Resource Center - Mouth and Teeth: Care and Problems

2: Cetylpyridinium chloride reduces plaque, calculus

What is Cetylpyridinium Chloride?

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