Getting Started in the Aesthetic Zone

I always get asked how I actually got started in Aesthetic Dentistry. You want to know the secret? It all started with understanding the posterior teeth before the anterior teeth...shhhh. Don't let the secret out of the bag.

Where on earth do we start with posterior teeth? I want to help point you in the right direction.

Have you seen patients with crack lines on posterior teeth and don't know which ones are the nasty cracks or the ones that can be monitored?

To help answer this eternal conundrum, we need to get back to fundamentals and start looking at this from another perspective. Let's first explore which intact tooth is the most susceptible to splitting i.e. Where have you seen THE MOST catastrophic cracks in unrestored teeth?

The literature is quite unclear in regards to this with some articles saying it is the lower second molars (Kang et al 2016, Mamoun et al 2015) and upper molars (Hilton et al 2021). My clinical experience tells me overwhelmingly it is the upper first premolars and then the lower second molars that can catastrophically fracture when unrestored - which agrees with Khera et al (1990).

Now it doesn't really make any logical sense that a little upper first premolar, near the front of the mouth can have the highest fracturing potential - until we look at it more closely. It's all about the tooth anatomy and a little bit about occlusion.

The reasons why upper first premolars and lower second molars have the highest potential to fracture:

1. Occlusal relationship with the antagonist. When we look at the opposing tooth for lower molars we have the large mesiopalatal functional cusp of upper molars. The upper first premolar has the sharp and prominent buccal cusp of lower first premolars. This can cause a plunger effect onto the opposing tooth.
   
2. Upper first premolars and lower second molars tend to have steep cuspal inclines and a deep central fossa/groove. This forms a wedging effect from opposing plunger cusps.
   
3. Anatomy of roots. Upper first premolars have two slender roots which are the smallest in any posterior tooth.
   
4. Relationship to the TMJ. Force magnifies the closer the tooth is to the TMJ.

Throw in a dash of parafunction or bruxism and we have a recipe for a catastrophic fracture.

So how can we use this information for good? My thought process is once a crack is identified, I assess the occlusion and tooth anatomy. If any of the points mentioned above is found, I consider this to be a potential nasty crack that could turn into a catastrophic fracture and then look at decreasing as many risk factors as possible. Understanding occlusion is one of the biggest key factors in getting started with predictable veneers. 

Keep an eye out for my emails where we will dive into other fundamentals that will help you in real world dentistry.