I have been trying to whiten my teeth and have bought every kind of toothpaste that says, ‘Whitening’; but none seem to work.  Why is this? -J.S. New Jersey


 To understand why whitening toothpastes don’t always deliver, we have to understanding the difference between ‘whitening’ and ‘bleaching’…terms that toothpaste manufacturers would prefer that you stayed confused about!



When teeth are young, the enamel is thick and not very transparent.  So as long as the surface of the teeth are free from stains and grime, the teeth will look fairly white.



If the surfaces of the teeth do have stains, then the teeth will look darker in the same way as a grimy windowpane will darken the view.  In this case any toothpaste that has enough abrasives in it can polish this grime off the surface and because of that the FDA permits a ‘whitening’ claim.



But as we age, the enamel becomes thinner and more transparent, revealing the yellow color of the tooth layer under the enamel, the ‘dentin’, more clearly. To lighten this yellow color, not due to surface grime, a bleaching agent will need to be used (and all surface grime must first be cleaned away to allow it to penetrate the enamel and bleach out the dentin)


Why do my jaws ‘click’? -E.B. New Jersey




The clicking is a result of a jaw joint that has had some wear and tear.  In a normal joint as pictured to the left, there is a cartilage disc that separates and cushions the ball and the socket.  



Because the jaw joint not only ‘hinges’ like an elbow or a knee, but also ‘slides’ (the only joint the body that does this), the ball of the joint has to be able to slide in the socket.  This happens when the disc is pulled forward by a little muscle (called the ‘internal pterygoid’).  Then the ball, sitting on the disc like a child sitting on a snow sled, glides forward.  In this picture you will notice that the lower teeth now touch the edges of the upper teeth as the jaw has come forward.  The muscle is like the friend who pulls the rope attached to the sled.



But if the muscle pulls the disc when the jaws are otherwise at rest—a frequent problem in people who have bite problems—then when the jaw does slide forward the ball no longer sits squarely on the middle of the disc but instead starts to ride on the rear lip of the disc.



If this happens over a long period of time the rear lip of the disc gets compressed and it no longer serves to keep the ball centered on it, but rather the ball can now slip off the back of the disc when the jaw opens.  This produces a ‘click’ and in early cases when the jaw closes the ball hops back onto the disc and then clicks yet again when the jaw opens again




In late stages the disc gets permanently displaced in front of the ball and then the clicking stops, but there can then be more serious TMJ problems.



In your website you describe a replacement for cast gold restorations made with a kind of liquefied porcelain.  Is this the same as ‘Cerec’?  -M.M., Washington, DC


The technology for restoring teeth with different kinds of porcelain and using different means of fabrication has grown by leaps and bounds in recent years.  There are now three widely used technologies for creating tooth replacements out of porcelain: stacking, pressing, and milling.  

Stacking refers to taking a porcelain powder, wetting it with distilled water to form a material with the consistency of wet sand, shaping it to the desired shape and then firing it in a kiln so that the porcelain particles fuse to each other to form a solid mass.  It is an old technology that has been used to make porcelain fused to metal or porcelain fused to gold crowns for decades. It is also the technique for making highly esthetic porcelain laminates that are used for enhancing the appearance of front teeth. Because porcelain made in this way shrinks as it is fired, it cannot be made to accurately fit anything that is shaped like a hole (an ‘inlay’) as it always has to be ‘overbuilt’ in size to accommodate the expected shrinking. Any shape that sits on a surface (an ‘onlay’, a porcelain laminate, a biting surface) can successfully be built with stacked porcelain and it is the most esthetic material we have.  In fact it can be combined with other techniques, although labor intensive to do so, for reasons described below.

Pressing refers to taking a porcelain ingot and melting it under high temperature and pressure and injection molding it into a three dimensional pattern of the missing tooth structure.  This technique is explained in more detail elsewhere on this website.  It produces restorations that have an extremely accurate fit, but the process involves many steps to accomplish and the varieties of porcelain that are available for pressing is fairly limited.  Also, for highly aesthetic requirements it can be cut back to allow an overglazing with stackable porcelain.

Milling is the latest technology.  It involves using a computer to create a three dimensional design of a tooth restoration on a computer screen, the data from which is fed into a milling machine that takes a block of porcelain and sculpts it down to the desired shape.  When finished it is baked in an oven to harden the structure.  This technology has become very popular because it involves many fewer steps then pressing and there are a wider variety of porcelains that are available that can be milled.  Lately the most common porcelains to be used are either lithium disilicate or zirconium.  Both of these are much harder than enamel and that translates into less breakage, but it also translates into much more wear on the teeth that come into contact with these restorations.  Therefore an important step in their fabrication is the highly skilled and labor intensive polishing of the surfaces before they are glazed in the hardening step.  Also, for better aesthetics, this material can be cut back to allow an overglazing with stackable porcelain.

Because so much of the work to make a milled porcelain restoration is done on a computer screen, some companies have developed machines different from the ones that they have been selling to dental laboratory technicians that dentists can purchase themselves in order to make these restorations right in their own office. One if these is the Cerec machine.  In these circumstances the dentist or, more likely, a trained dental assistant handles the design work ‘while you wait’.  It is marketed as a convenience to patients because the restoration is made in a single visit, as nothing has to be sent out to a dental laboratory.  But without the oversight of a trained laboratory technician, there is a limit to the refinement that these office made restorations can reach.  In regions of high aesthetic need, the skill and artistry of a trained laboratory technician, plus the additional equipment for cutting back and stacking porcelain, will be lacking in typical Cerec restorations.  In addition, the polishing step is often avoided by painting a ‘glaze’ over the surface and baked.  Studies have shown that this glaze layer wears off in about one year, exposing a microscopically rough underlying surface that can rapidly wear down the opposing teeth.

I want to thank Richard Pavlak, CDT, MDT, FNGS, the founder and director of Porcelain Plus Dental Systems of Cranford, NJ, for his expert help in answering this question.


Are there peer reviewed published studies on the health effects of the mercury vapor released from amalgam fillings? -G., Wantage, NJ


Elsewhere on this website you will find an extensive review of the whole issue of mercury toxicity.  In terms of studies in the peer reviewed literature there are many.  Here are just a few:


Summers, AO, Wineman, J, Vimy, MF, et al. Mercury released from dental ‘silver’ fillings provokes an increase in mercury and antibiotic-resistant bacteria in oral and intestinal flora of primates. Antimicrob Agents Chemother. 1993;37:825-834.


Siablerud, RL.  The relationship between mercury from dental amalgam and mental health. Am J Psychother. 1989;43:575-587.


Lorscheider, FL, Vimy MF, Summers, AO. Mercury exposure from ‘silver’ fillings: emerging evidence questions a traditional dental paradigm. FASEB J. 1995;9:504-508.


Eggleston, et al. Correlation of dental amalgam with mercury in brain tissue. J Prost Dent. 1987; 58(6): 704-707


Vimy, et al. Maternal-fetal distribution of mercury released from dental amalgam fillings. Exper & Molec Pathology. 1990; 52:291-299.


Also, the current issue (September 2015) of the Journal of the American Dental Association includes a cover story on the effects of mercury exposure on US dentists.  As all dentists wear gloves while working, the only route for routine exposure is via mercury vapor.  The research found that there is a correlation between mercury exposure and hand tremor in dentists:

Anglen, J, Gruninger, E, et al. Occupational mercury exposure in association with prevalence of multiple sclerosis and tremor among US dentists. JADA. 2015: 146 (9): 659-668.


Have you ever seen a correlation between people with autoimmune disorders and dental issues? I’ve started an immunotherapy medication for my Ankylosing Spondylitis and I have 3 cavities out of nowhere!!! Just wondering if these are related to the systemic issues in my body or more likely to the medications? Would love your insight!   -S.Y., Santa Rosa, Calif.


I often see correlations between auto immune disorders and dental issues, so you are not alone.  The connections are many and they run in all directions:

An auto immune disorder can affect the body’s ability to fight infection or it may affect bone metabolism–this can lead to an increase in tooth decay or gum disease, it can also alter the flow or quality of saliva which has a direct influence on susceptibility to tooth decay particularly along the gum line.  

At the same time, dental infections and diseases that are left unchecked can lead to various auto immune disorders.  It is not uncommon, as an example, for a patient with severe untreated gum disease to have adult onset diabetes and when the gum disease is treated the diabetes goes away.  Years ago I treated a patient who had recently been diagnosed with cardiac arrhythmia.  He had not seen a dentist in almost 20 years and needed about 10 teeth extracted as well as other treatment to clean up the rest of his mouth.  His arrhythmia vanished when his dental infections were eliminated. In both cases the heavy bacterial load present in the mouth led to high levels of these same bacteria circulating in the blood stream, leading to inflammation of the pancreas in the first case mentioned and in the heart in the second case mentioned.

Lastly, the medications used to treat auto immune disorders, be they non steroidal anti-inflammatory drugs, steroids, or inflammatory protein blocking drugs can each have side effects that can affect dental health.  When there is a bacterial infection in the mouth, such as tooth decay or some kinds of gum disease, the body must mount a specific kind of inflammatory response to overcome that infection.  If the inflammatory response is being muted by a medication, if will be easier for the bacterial infection to continue on and cause damage–such as tooth decay.  The other issue, and this is common, is that oftentimes there is a side effect from medication that reduces the flow of the saliva, and this can have a dramatic effect on tooth decay.

So it is hard to answer your ‘either/or’ question without saying that most likely the answer is ‘and’–all of the above could apply.  But we can often narrow down the possibilities on the basis of history.  For example, if you have had a long history of being free from tooth decay and if your auto immune condition has been present for a long time then it would be more likely that the recent change in your medication had more to do with the new cavities.  But if the medication is helping you then you would be best served by asking your dentist or hygienist for their advice on prevention.  This often includes issues of diet, daily oral hygiene, and may require the use of a fluoride mouth rinse.  In many holistic circles fluoride has a bad name, and I am not a fan of taking it systemically either in pill form or in treated tap water, but I have no problem recommending it for topical use for my patients who have auto immune disorders or limited flow of saliva.