Quote from Dr. Garrett Smith on February 8, 2019, 5:49 pm

Dental health is important to everyone.  Poison/"Vitamin A" ruins dental health in multiple ways.

Before we get into dental health, let's go into everyone's biggest concern whether they admit it or not, vanity.  Carotenoids stain your teeth, this is known.  Carotenoids are yellow, orange, and red.  Combine those colors, and brown results.  Between brown and yellow is where most teeth stain shades lie.  Note on the image below:  "beta-carotene is an orange colored chromogen that can stain teeth".

Tooth Whitening: What We Now Know

Figure 2
Chemistry of chromogen bleaching. A. β-carotene is an example of an organic chromogen with many conjugated double bonds; B. Chemical reaction of hydrogen peroxide with a chromogen double bond; and C. Chemical reaction of sodium hypochlorite with a chromogen double bond.

So if carotenoids can and do stain teeth, if one consumes more carotenoid Poison/"Vitamin A", do they have more carotenoids in their saliva?  Yes!

Saliva concentrations of some selected proteins and glycoprotein markers in man after supplementary intake of beta-carotene.

In the present study we investigated the effect of supplementation with beta-carotene (provitamin A) on the secretion of salivary glycoproteins and some antibacterial components. Eighty-nine men, drawn from a larger double-blind pilot study among Finnish men of a high socio-economic standard, participated in this study which lasted for 60 days. The men were allocated either to beta-carotene supplementation of 20 mg a day or to placebo treatment. At the end of the study samples of stimulated whole and parotid saliva were collected and examined for total protein as well as hexosamine, sialic acid, thiocyanate and the activity of salivary peroxidase. The secretion rate of whole saliva was calculated and the activities of lysozyme, a bacteria aggregating glycoprotein (BAGP) and secretory IgA were measured in parotid saliva. Significantly higher levels of beta-carotene, but not retinol, were found in serum and whole saliva in the beta-carotene group compared to the placebo group. Retinol or beta-carotene could not be detected in parotid saliva. No difference was found either in saliva secretion rate or in the composition of whole or parotid saliva between the beta-carotene and the placebo group.

Eat more carotenoids, have more carotenoids in your saliva, get yellow-orange-brown teeth eventually.

In terms of dental health, saliva production is extremely important.  From the American Dental Association:

Saliva

Saliva, or spit, plays a significant role in maintaining oral health. It is derived from blood and acts as the bloodstream of the mouth. What this means is, like blood, saliva helps build and maintain the health of soft and hard tissues. When saliva flow is reduced oral health problems such as tooth decay and other oral infections can occur. 

Less saliva, worse dental health.  Got it.  What does Poison/"Vitamin A" do to saliva production?  It lowers it.  Isotretinoin is also known as Accutane, and is 13-cis-retinoic acid:

Reduced salivary flow induced by systemic isotretinoin may lead to dental decay. A prospective clinical study.

BACKGROUND: The adverse effects of isotretinoin have been well documented, but dental side effects over the course of treatment have never been studied.

OBJECTIVES:To prospectively document the oral side effects experienced by a group of patients taking isotretinoin and to compare the changes in oral health and salivary parameters with a control group.

METHODS: A cohort study was conducted within the dermatology department at the University Hospital in collaboration with two private dermatology practices in Nice, France. Patients were treated at a dose of 0.5 mg/kg/day. The control group was made up of students from the University of Nice-Sophia-Antipolis. The salivary flow, the buffer capacity of saliva, the number of pathogen bacteria and the DMFT index (number of decayed, missing and filled teeth) were assessed at each visit.

RESULTS: Eighteen patients and 99 controls were available for evaluation. None of the oral parameters varied with time in the control group, whereas the DMFT significantly increased in the treated group (3.07 +/- 3.85 vs. 3.41 +/- 4.36; p<0.036). The salivary flow gradually decreased with time (p<0.004), but the patients recovered their baseline salivary flow 2 months after the end of the treatment.

CONCLUSIONS: This study clearly showed that patients treated with isotretinoin experienced oral side effects.

Pretty straightforward, retinoic acid reduces saliva production and thus increases dental disease.

Excess retinoic acid (Poison/"Vitamin A") causes defects in the tooth enamel!

Retinoic Acid Excess Impairs Amelogenesis Inducing Enamel Defects

Abnormalities of enamel matrix proteins deposition, mineralization, or degradation during tooth development are responsible for a spectrum of either genetic diseases termed Amelogenesis imperfecta or acquired enamel defects. To assess if environmental/nutritional factors can exacerbate enamel defects, we investigated the role of the active form of vitamin A, retinoic acid (RA).
[...]
Our observations support a model in which elevated RA signaling at fetal stages affects dental cell lineages. Thereafter enamel protein production is impaired, leading to permanent enamel alterations.

Does too much Poison/"Vitamin A" negatively affect tooth development as well?  We already know it causes birth defects, so this would seem quite plausible:

Effects of retinoids on tooth morphogenesis and cytodifferentiations, in vitro.

The first embryonic lower mouse molar was used as a model system to investigate the effects of two retinoids, retinoic acid (RA) and a synthetic analogue, Ch55, on morphogenesis and cytodifferentiations in vitro.
[...]
On the other hand, the stage-specific inhibition of tooth morphogenesis by excess RA is consistent with the hypothesis that CRABPs might protect embryonic tissues against potentially teratogenic concentrations of free retinoids.

Morphogenesis is the biological process that causes an organism to develop its shape.

What would happen when that process is inhibited (aka impede, hinder, hamper, hold back, discourage, interfere with, obstruct, put a brake on, slow, slow down)?  The answer is that things don't develop properly.

Excess Poison/"Vitamin A" gets in the way of all things oral health related.  Maybe you've seen an epidemic of MASSIVE problems in children's teeth today?  Maybe you're wondering why people who take pristine "mechanical" care of their teeth are still having major problems?

There are no coincidences.