When preparing anterior teeth for ceramic veneers, do you prepare the incisal edge flat or do you overlap and extend down the lingual aspect of the tooth? To assist you in making that decision, consider the following factors:

  1. Will the veneer be bonded to enamel or dentin on the facial aspect of the tooth?
  2. Are there functional or parafunctional issues that need to be addressed?
  3. Are there structural compromises in the tooth?
  4. Is there a significant morphology change occurring, retroclining or proclining tooth position?

Generally if the ceramic veneer is going to be bonded to enamel and there are no considerations other than restoration of the tooth for esthetic reasons, it is easiest for the clinician to prepare the incisal edge flat. This then makes it easier for the technician to design a well-fitting restoration because there will be less detail in the preparation that needs to be accommodated during fabrication.

flat prep
wrap prep
proclined tooth
retroclined tooth

If you want to increase the retention of the veneer or are planning morphology changes for esthetic, functional or structural reasons, I recommend that you overlap the incisal edge and prepare into the lingual aspect of the tooth. This increases the resistance form of the preparation so that the ceramic engages the lingual aspect of the tooth.

The additional reduction of the tooth allows the technician to make the morphology changes to the restoration without creating an incisal edge that is too thin or too thick. A diagnostic wax-up is extremely helpful in this type of case to determine how far the preparation must extend into the lingual surface.  


Comments

Commenter's Profile Image Kevin S Grimm DDS
March 22nd, 2013
There are no significant studies to show wrapped is better than flat. Porcelain thrives with compression and fails in sheer. If one wraps then 2 factors come in play. 1. Path of insertion. This is one of the most important but overlooked factors. Wrapping creates a more complex path of insertion. 2. Wrapping creates an unsupported thin vestage of porcelain on the lingual more susceptible to fracture.
Commenter's Profile Image Daniel Mairani Dds
April 4th, 2013
Sometimes I have the lab overlap slightly even though I don't want the length or prep for it. It just helps with the seating then I cut back and re-polish. I have had some where the surface is so flat the veneer would slide around during placement and not seat properly. Mind you , these were not reduced very much in the first place.
Commenter's Profile Image Jill
April 7th, 2013
nice tip! thx
Commenter's Profile Image Bob Winter
April 8th, 2013
To all that responded to this blog, thank you. Choosing the least complicated preparation design is always my first suggestion, however there are times when overlapping is indicated as was listed in the blog. The concepts of tooth preparation for ceramic veneer restorations can be personal and is controversial. The literature supports both concepts of flat incisal reduction and a palatal chamfer. Two recent studies (Schmidt, Chaiyabutr, Phillips, & Kois, 2011; Chaiyabutr, Phillips, Ma, & Chitswe, 2009) conclude that a preparation design with a palatal chamfer margin has a significant effect on the load to failure value and a significantly higher failure load, than a shoulder finish line design alone. I only recommend an overlap of the incisal edge if there is a compromise in the remaining tooth structure, if there is a considerable morphology change planned, or if there is significant bonding to dentin rather than enamel. References: Chaiyabutr, Y., Phillips, K. M, & Ma, P. S., & Chitswe, K. (2009). Comparison of load-fatigue testing of ceramic veneers with two different preparation designs. The International Journal of Prosthodontics, 22(6), 573-575. Schmidt, K., K., Chaiyabutr, Y., Phillips, K. M., & Kois, J. C. (2011). Influence of preparation design and exiting condition of tooth structure on load to failure of ceramic laminate veneers. The Journal of Prosthetic Dentistry, 105(6), 374-382. doi: 10.1016/S0022-3913(11)60077-2.
Commenter's Profile Image Noek
December 14th, 2014
Thanks for this ariticle. What will you recommend if the patient has 1. An edge to edge bite. 2. Parafunctional habits like bruxism