Recording the bite in worn dentition

When patients’ teeth are affected by wear process their main concern is, usually, esthetics. To enhance the smile and recreate ideal proportion in the anterior zone we need some space to recreate the function and then esthetics. Professor Jean Francois Lasserre from Bordeaux call it “the bio-functional esthetics”.

It it highly recommended that, in these cases, the vertical dimension be increased in order to reduce the biological cost of our treatment (Vailati F, Fradeani M, Koubi S).

This is why it is highly recommended to get all the needed data to let the technician wax-up the missed volume in the new free space which has been created by the new vertical dimension. The data you should collect, hence, is:

– face, smile, intraoral picture

– impression of both arches

– record of the face references with Ditramax device (www.ditramax.com)

– free hand composite shape modeling on the 2 central insisors (buccal and palatal) to set the length and the new incisal edge to create the new volume we are looking for. I can’t stress enough how this one step is the key factor to build the new full arch.

Fig.1

Patient was affected by abrasion and erosion and now is looking for a smile improvement. Treatment planning is to reconstruct the upper arch only with an increase of the VDO. Monolithic occlusal veneer, palatal veneer with the new incisal edge will fill up the new free space in order to follow a minimally invasive approach and a prep less or almost no prep concept.

Fig.2

Free hand composite rough shapes are built to set the new length and the ideal incisal edge position.
Same protocol is applied to the palatal anatomy on the 2 central incisors. Then it is very important to check the new space created in the posterior area to see if we have or not enough available space or if the final esthetic will be modified by the added occlusal veneer. If the smile line must not be modified then we will have to reduce the increase of the VDO. In this case a smile improvemente is expected which means a lengthening of the lateral corridor.

Fig.3

When the esthetic parameters are validated with the JIG recorded in centric relation , it is crucial to record the bite in this position. We highly recommend to use a bisacryl material instead of bite registration silicone to get a very repeatable position without distortion.
This is why we use the Luxabite (DMG) as an accurate bite registration. The practitioner has to inject a small quantity on the occlusal surface in order to remove and replace it without fracture. The setting time must be minimum of 2 min in order to have the complete curing of the resin.

Fig.4

The wax up is performed by the technician (Hilal Kuday, Bodrum, Turkey) and follows exactly the clinical observations and recreates the lost volume.

Fig.5

In order to ideally transfer the wax up in the mouth and improve the accuracy of the full mock up, the wax up is scanned and a 3D printed template is created from the .stl files in order to get the rigidity of the resin. This template is relined internally with a light body silicone to increase the friction with the existing and avoid pumping effect during the insertion in the mouth.

Fig.6

This 3D printed template is filled with a bis-acryl resin (luxatemp star, DMG) and inserted in the mouth to perform the full mock up. You can see the new smile line in the anterior area and the lateral part as well as it was expected during the VDO record.

Fig.7

The full mock up is very useful to check simultaneously the functional and the esthetic outcome.
Also, the accuracy and the esthetic of the bis-acryl resin (luxatemp star, DMG)  is very useful to communicate with the patient.

Fig.8

Following the regular workflow of the full mock up concept, the posterior mock up is used as a precise guide for the posterior prep and offer the required space for the occlusal veneer (table top)

Fig.9

Almost no prep is needed to seat the occlusal veneer because it is additive dentistry. Only a mark is required to visualize the margin and let the technician read the perimeter of the restoration. Also, it is important to offer thick margin for the table top to avoid chipping and fracture.

Fig.10

Each veneer is bonded, one by one, using a flowable dentin body  (enamel HRi flowable UD1) resin cement to reduce the visibility of the margin. Also, some barely visible waves have been created to improve the esthetic integration of the restoration.

Fig.11

Final view of the restoration made with emax LT A1. If the patient is looking for higher esthetics, buccal veneers can be proposed.

Fig.12

Palatal view of the monolithic lithium disilicate palatal veneer. Thanks to the translucency of the material, the mimic effect is very nice also for the functional part.