Tissue development preparation technique (TDPT)

Tissue development preparation technique (TDPT)

The current challenge in reconstructive dentistry is to obtain excellent aesthetic results while preserving the biological structures involved as much as possible. Thanks to the introduction of high strength etchable dental ceramics, clinicians and technicians have materials and procedures at their disposal that allow them to restore aesthetics and function through a minimally invasive approach. New-generation all-ceramic restorations and adhesive systems allow a greater preservation of residual hard tooth structures, especially with regard to single elements. (2)

Gurel et all found that veneers, bonded in dentin have 60% lower success rate.  Recent years have seen increasing demand for treatments aimed at improving dental aesthetics. In this context, both patients and dentists prefer to preserve dental structures as far as possible, thanks to technological advances, especially in adhesive dentistry, new materials and minimally invasive techniques.(1)

A correct diagnosis, comprehensive treatment plan, and an interdisciplinary approach are necessary to obtain optimal conservative and predictable aesthetic results. Nowadays, there are many digital softwares that can make it easier to predict the final result. In this way we create a guideline to serve as a starting point for where it would be right to place, for example, the gingival contour and how it would look harmonious and aesthetic. Based on the REBEL software, we can present to the patient with the new smile design and properly plan the preparation line so we can get the perfect gingival aesthetics.

Classifying the geometry of the finish line, which margins are broadly divided into two main classes: vertical and horizontal.

Vertical preparations such as featheredge have been considered unsuitable because of poor marginal adaptation, horizontal over- contouring, and possible distortion of the cast during porcelain ring.(11)

Among margin designs, dentists usually prefer horizontal, such as shoulders or chamfer, over vertical preparation, such as featheredge. This is most likely for practical reasons, including that horizontal preparations are distinct; are readily visible on the prepared tooth, impression, and achieve a neat margin on the relined provisional restoration; and should produce better seating for the restoration.
However, according to the literature, the vertical geometry rather than the horizontal has proven to reduce the marginal gap of the restoration and create a less irritating environment within the gingival sulcus.(9–11) Recent clinical studies have discussed the application of featheredge tooth preparation in different clinical situations.(12–14)

Adhesive bonding techniques in combination with tooth-coloured restorative materials are one of the greatest achievements of restorative dentistry. Today ceramic veneers are used to restore the biomechanics of the dentition, to establish adequate function, to mask highly discoloured endodontically treated teeth, and for many other purposes. This includes analyzing the case, defining the treatment goal, determining the right shade, selecting the most suitable ceramic material, finding the best preparation design, and choosing the most appropriate adhesive concept.(9)
This clinical case describes the rehabilitation of the upper anterior region by means of minimal preparation, with the Tissue development preparation technique (TDPT) cervical margins. This technique was designed to create an anatomic crown with a prosthetic emergence profile that simulated the shape of the natural tooth.(7)

Initial situation with smile

Fig.1

Initial situation with smile.

The presented clinical case describes dental treatment which includes achieving a high aesthetic result using the tissue development preparation technique In this clinical situation a 28 years-old female patient presented at our dental practice with a desire for a new smile and naturally white teeth.

Intraoral situation

Fig.2

Intraoral situation.

After a trauma in childhood and early endodontic treatment of the upper central incisors, discolouration of the teeth occurs from the root canal filling agent.

Retracted, contrasted view of incisors

Fig.3

Retracted, contrasted view of incisors.

Intraoral photo with retracted lips. There is a significant difference in the colour between the central and lateral incisors.

thin soft tissue biotype

Fig.4

Another important feature in this case is that the patient has a thin soft tissue biotype, which should be taken into consideration at the positioning and edges of future restorations so that the gingival contour can be harmonious in order to achieve the desired maximum aesthetic effect.
After discussing the possible treatment options it was decided to place four veneers of the upper frontal teeth.

Initial X-ray of the upper central incisors

Fig.5

Initial X-ray of the upper central incisors.

For this purpose firstly an endodontic retreatment was performed followed by internal bleaching. (Opalescence Endo 35% hydrogen peroxide). Meanwhile, the patient also proceed with home dental bleaching (White Dental Beauty Teeth Whitening gels 10%CP (Carbamide peroxide) to achieve the desired colour.

Facial map with landmark points and type

Fig.6

Facial map with landmark points and type.

Using Visagismile software based on patient’s personal and psychological characteristics an individual smile design was discussed with the patient and the necessary corrections were done.

Personality interview

Fig.7

Personality interview.

Final design of the software

Fig.8

Final design of the software.

The optimal tooth shape was determined by an interview (questionnaire in the software). Based on the data from the interview, a software algorithm automatically calculates the temperament, as perceived by the patient.

Based on it wax up was produced in the dental laboratory

Fig.9

Based on it wax up was produced in the dental laboratory.

Mock up

Fig.10

Mock up.

After the composite mask was transferred to the mouth – clinical previsualization by means of a mock-up, the shape, size and projection of the teeth were discussed. After the patient’s approval, we moved to the next important stage of treatment. The four upper incisors were prepared using the tissue development preparation technique the purpose of which is to re-shape the gingival contour and create a natural emergence profile of the future restorations.

Preparation technique

Fig.11

Preparation technique.

Initially, the teeth were prepared with a 0.5mm horizontal margin design. After that the margin was removed and vertical preparation, using a longneck bur was performed. After preparing the CEJ, the bur is rotated with an angulation, following the root surface, reaching the the bone margin, without touching it, shaping a slightlY concave root surface.

First provisionals

Fig.12

First provisionals.

Immediately after the preparation provisionals were placed – 0.5mm from the gingival margin with a very thin edge.The crown is adjusted with an over contoured equator. The provisional veneers were placed to serve as a guide for the the future restorations, as well as for the shaping of soft tissues. At this stage the most important thing is that they do not irritate the soft tissues, leaving at least 0.5mm distance from the gingival margin to allow a complete healing process.

Fig.13

Second provisionals between five and eight weeks after tooth preparation. There is a significant difference in soft tissue volume, indicating a complete healing process. During this period, the patient was called for control visits to evaluate the healing process and to follow the level of the gingival margin.

First try in

Fig.14

Тhe most interesting part of the follow-up of this clinical case is the significant difference in the gingival marginal level of the of the two lateral incisors. The picture above illustrate how the gingival margin was placed during the first try in of the veneers.
In this case, we decided to wait as long as necessary time, because after a vertical preparation we managed to create a thick soft tissue biotype, allowing the gum to grow to the level we set with the provisional restorations.

Fig.15

For this purpose, we asked the dental technician to shorten the level of the left lateral incisor to the desired height, as shown on the working model, knowing that based on the increased thickness the tissue will grow
Two weeks later a second impression, using two retraction cords was taken and new provisional restorations were placed at the final planned vertical position.

Occlusal view after increasing VDO

Fig.16

Occlusal view after increasing VDO.

Meanwhile, a minimal increasing of the vertical dimension of occlusion was performed in order to harmonize the occlusion and to create perfect contacts.

After preparation frontal view

Fig.17

After preparation frontal view.

The final stage of the treatment was to fix the final veneers after the healing process was finished and there was adequate integration between soft and hard tooth tissues.

After preparation occlusal view

Fig.18

After preparation occlusal view.

Try in

Fig.19

Try in.

Adaptation of the veneers

Fig.20

Adaptation of the veneers.

After checking that dental fit and gingival adaptation were correct, the colour shade of the cement was selected using try-in pastes (Variolink Esthetic, Ivoclar Vivadent).

Firstly, the teeth were isolated with a rubber dam for achieving perfect isolation and moisture control during adhesive cementation.

Adhesive protocol

Fig.21

Adhesive protocol.

Firstly, the teeth were isolated with a rubber dam for achieving perfect isolation and moisture control during adhesive cementation.

The teeth were etched with 37% orthophosphoric acid etching gel (Total Etch, Ivoclar Vivadent) for 30 seconds and the veneers with 5% hydrofluoric (IPS Ceramic Etching Gel, Ivoclar Vivadent) for 1 minute. Both the teeth and the veneers were then washed and dried.

The finished ceramic veneers before preparing them for luting

Fig.22

The finished ceramic veneers before preparing them for luting.

Adhesive was applied to the dental enamel (Syntac Bond Ivoclar Vivadent), and a silane coupling agent (Monobond plus, Ivoclar Vivadent) was applied to the internal face of each veneer, followed by the adhesive (Adhese Universal, Ivoclar Vivadent) without undergoing polymerization. Then, the veneers were cemented with photopolymerizable resin cement (Variolink Esthetic LC Light, Ivoclar Vivadent) one by one, starting with the central teeth, fitting each veneer in place and polymerizing for 2 seconds in order to remove excess cement.

full polymerization

Fig.23

Afterwards full polymerization was performed for 40 seconds per tooth vestibular and palatal behind oxygen barrier. Lastly, any remaining excess cement was removed with a scalpel blade.

The final result after cementation

Fig.24

The final result after cementation.

The patient smile

Fig.25

The patient smile.

The final result after cementation

Fig.26

The final result after cementation. The tissue on the lateral incisor is 1 mm apical from the edge of the veneer.

The perfect healing of the tissues over the veneers after 6 months

Fig.27

The perfect healing of the tissues over the veneers after 6 months. The tissue grew over vertically on the veneer edge in coronal direction.

Final result occlusal view

Fig.28

Final result – occlusal view. The thickness of the tissues is clearly visible.

Final result lateral view

Fig.29

Lateral vision.

The patient was recalled to the clinic after 15 days, 3 and 6 months to assess the health of the soft tissues, checking that gingival scalloping adjacent to veneers was symmetrical and that prosthetic aesthetics were optimal.

Discussion

The suggested workflow is predictable protocol to create a digital architecture plan of the smile and an noninvasive way of treatment of the hard and soft tissues.

If the patient accept the mock up, the suggested technique is an easy way to duplicate it and keep the predictable outcome.

The vertical preparation is creating a concave emergence profile of the CEJ and allowing the soft tissues to fill in and increase its volume.

The digital measurements showed an average gain of 0,7mm of horizontal and 0.5mm of vertical growth of the soft tissue volume. The increased volume is a predisposition for a longterm stability of the gingival contour.
In order to have an undisturbed healing the margin of the provisional restoration should be a knife edge and at least 1mm coronary of the margin. Once it is healed with the second provisional restoration we can push the tissues to the desired position, but it will be a healthy and thick tissue.
The vertical preparation is allowing the clinician to plan the perfect zenith of the soft tissues and the dental technician could create it, without being focused on the soft tissues. Even by pushing them more apically they migrate vertically at the papillae space and as shown above- if the margin is placed a little more coronary, by having a thick tissues it will grow enough to reach it.
Once the level of the emergence profile is fixed at the planed level, the second provisional restoration should be replicated and the treatment finalized.
In our dental center this technique is applied since 2012 and more than 700 cases are finished. We observe stability of the tissues in all cases that we follow and the great percent of patient acceptance and satisfaction.
In the next years more studies including histology should be done in order to prove the principles.

Conclusions

We opted to apply TDPT philosophy, which would make it possible to modify the height of the gingival margin without any need for surgery, simply by modifying the emergence profile to make it more concave or more convex, which would allow the gums to thicken and adapt to the new shapes. In this way, it is possible to achieve greater gingival stability in the medium and long terms, improve the restorations’ emergence profiles, facilitate oral hygiene maintenance, and create more natural appearance.

Bibliography

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