Sense of preservation in treating worn dentition. Full mock up and digital approach.
The treatment of tooth wear is an increasingly popular topic. Young patients are as affected as older people, and every dentist happens to be facing these situations, so proper (ultra-conservative) treatment of eroded dentition becomes a challenge of everyday dentistry.
The purpose of raising the vertical dimension of occlusion (VDO) is to reconstruct the occlusal morphology of worn dentition with the least invasive preparation, and to restore the smile line with an adequate thickness of the restorative material. This allows the clinician and technician to have more freedom to recreate occlusal harmony, improve the bite, and reduce stress on the muscles, while creating a sufficient inter-occlusal space to restore proper anterior guidance and correct the occlusal anatomy.
For this kind of treatment, clinicians need to record many parameters (facebow, impression, bite registration…) to allow the technician to recreate the ideal space needed for the reconstruction.
Here we present a new, faster and safer way. Modjaw is a new device that allows recording jaw movements and contact points precisely thanks to an accurate tracking process on both jaws.
Increasing of VDO is safe and well-tolerated by healthy patients. In most cases, recreating the ideal morphology and obtaining optimal esthetic results with minimal preparation would be almost impossible without changing the VDO. This step is crucial to creating the ideal aesthetic and functional project. In other words, the required space for anatomic reconstruction will dictate the new VDO recorded on the patient, giving the technician all of the information needed to create the new design.
This article presents an indirect approach for treating eroded dentition on young patients using the full mock-up approach with a new digital tool.
40-years-old male patient with severe abrasion and erosion combined. Esthetic analysis showed asymmetry in the smile line.
From a lateral view, smile line modification due to incisal destruction is clearly visible.
The intra-oral picture shows how the upper arch is more affected than lower arch.
The clinical analysis also highlights a very good integrity of buccal enamel, which may be taken into consideration in treatment planning and type of restoration.
The incisal anatomy is severely affected by both erosion (palatal surface) and abrasion (incisal edge). Treatment should include the creation of an artificial layer of enamel to restore the lost structure.
In the posterior area almost all occlusal enamel was missing and dentin was exposed. Cusp cupping is typical in the erosion pattern. Some old composite fillings needed to be replaced prior to starting the treatment to allow for ideal design of the occlusal veneers and homogeneous thickness. Treatment planning here is very simple, and customized according to the selective destruction. Palatal, occlusal and buccal veneers will be fabricated to restore both the upper and lower arch.
In order to simulate the ideal physiological motion frame, a new and innovative digital device was used. The Modjaw system is able to track very precisely the jaw motion thanks to calibrated trackers provisionally bonded on the mandible.
After calibration, the dentist and the technician can record the reference position and open the bite in the frame outlined by all anatomical requirements.
Jaw movements are recorded and a replayed to identify the space needed in anterior motion area. You can accurately measure the desired thickness of the new palatal anatomy and the lengthening of the lower incisal edge.
Then with exocad a digital wax up is performed.
Once the design is completed, the biggest challenge for the dentist is to transfer it in the mouth without distortion. A standard silicone index is an option, but can lead to significant distortion of the resin during the placement in the mouth and setting time. Another option is to print out from the final design a resin template which will be relined by light body silicone (Honigum Light DMG Hamburg) able to create friction in the mouth, and avoid pumping effect of the previous silicone index thanks to its rigidity.
Once the digital wax up is complete, .stl files are sent to the printer to create upper and lower arch models. Then two 3D-printed templates are relined with a light body silicone and filled with LuxaCrown resin syringe (DMG Hamburg). After the 30-second setting time, excess material is removed from the buccal area.
3 additional minutes are needed for the material to reach a high conversion rate to get the best physical properties. This crucial step, called the full mock-up, was proposed 10 years ago to simplify the protocol and treatment of worn dentition. Due to the outstanding mechanical properties of this resin, the patients are invited to wear this full mock up sometimes for long period (1-2 months) as a test drive. Although we’ve been using pure bis-acryl resins in the past, they are not able to last for long testing periods (1-3 months). This is why LuxaCrown is much more suitable for this long temporary period.
The advantages of this injectable material are the following:
– easy handling (simple injection)
– Good aesthetics
– High mechanical properties for the testing phase of a new vertical dimension
The accuracy of the full mock up is very good which significantly facilitates the upcoming clinical steps. Here you can appreciate details of the occlusion before touching anything with a bur.
In less than 5 minutes the practitioner is able to validate the esthetic and functional outcome and leave the patient to test the proposal.
After one month of testing the validated project, which was not mandatory in this case (related to rise of VDO beyond 5mm in the anterior area) occlusal preparations are directly performed on the mock up to control cutting thickness. In other words, preparations are guided by the final occlusal anatomy. Three horizontal grooves of 0.5 mm through the LuxaCrown mock-up are performed with a rounded bur.
In the anterior, once the mock up is removed, the design step is concentrated in creating small, wavy irregularities like to facilitate optical integration for the incisal extension of the palatal veneers.
Final view of the preparations. The buccal enamel is preserved.
Palatal preparations are limited to only one spot around cingulum to improve or facilitate stabilisation of the palatal veneer.
Each ceramic restoration is bonded, one by one, using individual dam. You can note the excellent biological and optical integration of the restoration made with multi color leucite reinforced block (empress CAD Multi Ivoclar Vivadent).
Thanks to the bonded restorations, teeth are reinforced and protected.
Optical integration of the incisal edges. Margins are visible at macro view but invisible at social distance.
Lateral view of the final restoration. A polishing sequence is highly recommended to improve the continuity between the ceramic and natural enamel in order to reach a good, long-lasting marginal seal.
Occlusal view, upper arch.
Occlusal view, lower arch.
Intraoral integration of the functional veneers (CDT Hilal Kuday, Bodrum, Turkey).
Monolithic veneer just stained made out of leucite-reinforced blocks.
In today’s world of bonding, tissue preservation is critical, and many clinicians often forget, or bypass the strict rules of minimally invasive tooth preparation techniques and designs for fixed prostheses, because of technical challenges, time constraints, or lack of training. Treating dental wear in younger patients is also an important challenge for clinicians. However, patients can be treated with a very low biological cost due to the performance of current materials. The difficult balance between biology, esthetics, and function can be achieved. At the same time digital tools such as the Modjaw device can be a real plus for both the clinical and lab team to perfectly simulate the jaw movements, and then produce accurate and customized full mock up to convert into final restorations with almost no correction after the bonding protocol. To increase the vertical dimension beyond 5mm it is recommended to let the patient test and integrate the new function for a couple of weeks until patient reach the confort and a complete clinical silence.
The goal of this minimalistic approach is to simplify the procedures for clinician and provide strict guidelines in order to make the treatment feasible, repeatable, and predictable.
Credits: Hilal Kuday DT
– Koubi S, Gürel G, Margossian P, Massihi R, Tassery H. Aspects cli- niques et biomécaniques des restaurations partielles collées dans le traitement de l’usure: Les table top. Réal Clin 2014 ; 25 (4): 327-336.
– Koubi S, Gurel G, Margossian P, Massihi R, Tassery H. A Simplified Approach for Restoration of Worn Dentition Using the Full Mock-up Concept: Clinical Case Reports. Int J Periodontics Restorative Dent. 2018 Mar/Apr;38(2):189-197
– Vailati F, Belser U: full month adhesive rehabilitation of a severely eroded dentition: 3 step technique part 2. Eur J Esthet Dent. 2008 Summer;3(2):128-46.