Oakville Dentist Dr Steven Rosenblat

 

 

 

 

Keeping in touch by blog!

Thank you for spending a few minutes and checking out my blog!

This is a great way for me to keep you informed about what's new at Oakdale Dental.  You'll find stories about todays dentistry and how it can make your life better and healthier, and sometimes some random thoughts I hope you find interesting. 

If you are already one of my patients, let me know what you think.  Any topics you would like to read about or questions you have, just send me an email.There is lots of information already on this site and my other practice website: Oakdale Dental! 

For those of you who I have not had the pleasure to meet yet, I'm glad to have here and feel free to drop by and pay us a visit at Oakdale Dental in beautiful Oakville.

So, come back once in a while...I try to post regularly and have some interesting things for you to check out and maybe a story or two to tell.


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"Great things start with a smile!" Dr Rosenblat

« What if you break porcelain crowns? | Main | How about Partial Dentures? »
Monday
Oct192009

Why is it black at the gumline of my crown?

Patients often enquire about dark lines that appear at the gumline of crowns.  Sometimes it can be a wide area and there may be darkness appearing around the gums of a tooth that has a crown too.  The reasons are usually related to how and a crown was fabricated and how the light that lets you see your teeth affects your teeth and gums.  A little bit of background information will help explain all of this.

When you look at teeth (or anything you can see) what you are actually seeing is the light that bounces off each tooth.  But light doesn’t just bounce off a tooth; it also bounces around inside the tooth, and comes out of different areas of the tooth including from below the gums.  This means a tooth has translucency (think light passing through frosted glass).  Today when a crown is fabricated we try to mimic these characteristics by using porcelain, layered with translucent as well as opaque layers to mimic the enamel and dentine layers in natural teeth.  Porcelain is fragile and in many of the ways we use it for teeth it needs support. Traditionally a thin layer of precious metal including gold and palladium (because or their biocompatibility and strength) as thin as ½ mm is used.  So you may now start seeing the difficulty in making a natural looking crown.  A thin layer of gold at the edge or a crown will show if the crown edge is not below the gumline (where a dentist often places it).  In the back of the mouth a line of metal is not an aesthetic problem as no one can see it, but in the front of your mouth it is definitely unattractive.  And if the gums recede the line will appear.  So today we very often design crowns that need metal support with only porcelain at the edge so there is no possibility of seeing metal at all.  These types of crowns supported by metal are mostly used in the back of the mouth because they give you a very strong and long lasting crown with good appearance, but we can do better in the front where it counts. 

As I mentioned above, light needs to bounce around inside the tooth and obviously metal won’t allow this and so any tooth root exposed by receding gums will look darker than nearby teeth and so can the gums at the edge of a crown (if they are thin enough that you can see a darkening of the underlying tooth root). 

Newer technologies allowing all porcelain crowns can solve a lot of these problems of light “illuminating” the crown and gums.  But some teeth are crowned because they are dark or discoloured and we want the light to be blocked so we can improve the appearance of the teeth.  Examples of this are teeth that have had root canal treatment, some of which have metal posts that can also darken the tooth root.  Here we can use either the traditional metal supported crowns in the posterior of the mouth or special newer materials like Zirconium (think artificial diamonds- Zircons) to act as metal by being strong, blocking the darkness underneath but having the advantage of being white so adding porcelain on top of it give us a very natural appearing crown.  

Dentistry is getting much better at mimicking nature but it’s a tough job!