Tooth-supported all-ceramic single crowns (SCs), fixed dental prostheses (FDPs), and a removable telescopic restoration

CHAPTER 5

Anterior regions

2.5.1 Full-mouth rehabilitation

Posterior regions

2.5.2 Tooth-supported, all-ceramic three-unit fixed dental prosthesis (FDP)

2.5.3 The 3D-printed prototype

2.5.1 Full-mouth rehabilitation

■ Maxillary arch: veneered, all-ceramic crowns, and fixed dental prostheses (FDPs) (Lava Plus, 3M, Seefeld, Germany)

■ Mandibular arch: individually veneered removable telescopic restoration (Gradia, GC, Leuven, Belgium)

■ Endodontic retreatment

■ Ball attachments

This first case details the full-mouth rehabilitation of a failing and insufficient old dental restoration by means of veneered all-ceramic crowns and FDPs in the maxillary arch and a removable restoration in the mandibular arch.

Assessment and treatment planning

A 72-year-old female patient presented herself at the clinic seeking general treatment and an esthetic improvement of her entire dentition. The patient was healthy and did not take any medication; however in the past she suffered heavily from a chemotherapy treatment that led to a long period of vomiting, which explained the severe loss of tooth substance.

One of the patient’s chief complaints was the poor esthetics of her fixed restorations. Poor adaptation of the crowns with overcontoured margins made it very difficult for the patient to properly clean the restorations, leading to generalized gingivitis.

The patient’s second wish was to receive fixed dental restoration if possible of both arches, and restore the masticatory function to allow her to properly eat again and not feel embarrassed in public.

At the beginning of the comprehensive treatment, a detailed diagnostics process was required for the evaluation of the single tooth prognosis and the potential strategic relevance. The quality of the existing root canal treatments was analyzed and furthermore, an extra- and intraoral esthetic analysis was performed to determine the new outline of her teeth.

In general it was planned to maintain as many teeth as possible by means endodontic retreatment along with an opening of the vertical dimension. If needed, this would entail a crown lengthening and implants to replace failing teeth to avoid long-span FDPs on the compromised teeth.

The final maxillary restoration was planned to be fabricated from a semi-translucent multicolor as for the mandibular arch with the reduced number of abutment teeth and a lack of bone. It was most likely that a removable restoration supported from a precious alloy would be the treatment of choice.

As this was a major change, a long-term provisional phase for the patient to adapt to the new vertical dimension and the overall shape and size of her new restorations was foreseen (Fig 2-5-1).

Diagnostics

The patient’s chief complaint was her compromised esthetic appearance, especially in the maxillary anterior teeth. However, she was also aware that some of her teeth and restorations were not in good condition. This was due to several severe chippings, and to constant bleeding and a bad taste she sensed while trying to clean her restorations.

Evaluating and defining a sound prognosis for her teeth with these types of metal-based existing restorations in place was extremely difficult, if not impossible.

The panoramic radiograph and the peri-apical radiographs allowed for a first prognosis and a categorization of the teeth into three groups (safe, questionable, and irrational to treat) but this assessment could only be finalized once the failing restorations were removed and the substrate beneath could be examined.

To develop a clear treatment aim, alginate impressions of both arches were created along with a facebow. The laboratory then developed a full wax-up including a vertical augmentation of the bite.

As the existing restorations were very bulky, the wax-up created in the dental laboratory was already based on a subtractive preparation of the casts; consequently, no direct mock-up could be performed. However, at least the desired shape and design of the new restorations could be discussed with the patient based on the wax-up in the articulator.

In the clinic, the failing restorations were removed and the assessment for the teeth could be reviewed.

The wax-up was then transferred into a direct provisional, allowing the patient at this early treatment phase to test the planned restorations, to improve her esthetics, get used to the new shapes and volume of her planned restorations, and finally verify the raised vertical dimension.

The following treatment plan was then developed according to the diagnostics and prognosis of the maintaining teeth (Fig 2-5-2).

Bite and facebow registration

In the dental laboratory the conventional alginate impressions were poured with plaster and diagnostic casts were fabricated. Thereafter, they were articulated based on the preliminary bite registration based on the copy of the old removable restoration in the mandibular arch and by means of a facebow that was acquired for the correct three-dimensional (3D) orientation of the casts in the articulator (Fig 2-5-3).

Wax-up

In order to visualize the final treatment outcome and also its potential limitations, a full wax-up was performed on two conventional plaster casts that were articulated by means of a facebow. The vertical dimensions were raised by 6 mm on the incisal pin.

As the existing anterior restorations, still present in the casts, were very bulky it was decided to already prepare the teeth on the casts so that a natural contour could be developed by the dental technician. Unfortunately, this made it impossible to actually visualize the prospective treatment before the actual removal of the restorations.

Amalgam replacement and direct composite build-ups in the mandibular arch

Under rubber dam, the amalgam could be safely removed and then pretreated. The composite build-up (Tetric Classic, Ivoclar Vivadent, Schaan, Liechtenstein) was guided by transparent silicone keys (Memosil 2, Kulzer, Hanau, Germany) that reflected the diagnostics and made the build-up extremely predictable and efficient (Fig 2-5-4).

Removal of insufficient restorations in the maxillary arch

In a first treatment step, the insufficient restorations in the anterior and posterior segments of the maxillary arch were carefully removed and evaluated (Fig 2-5-5).

Endodontic re-treatments and build-ups

After the removal of the old restorations, access to the previous root canal filling was possible and rubber dam was placed. The endodontic retreatment was performed using a combination of manual endodontic instrumentation (K files, Maillefer, Tulsa, OK, USA) and machine-driven endodontic instruments (ProTaper Universal Files, Maillefer). The previous root canal filling was thereby meticulously removed and the root canals of both teeth were disinfected with Na(OH)₂. Thereafter, the root canals were filled with gutta-percha, condensed, and fixed with aid of the cement AH 26 (Maillefer). At the next meeting and after the setting of the cement, the two root canals were prepared for titanium root posts. The posts were adhesively inserted using a self-adhesive universal cement (RelyX Unicem, 3M), and the composite build-ups were made with a light curing composite (Tetric Evo Ceram, Ivoclar Vivadent), associated with the respective dentin and titanium pretreatment steps (Syntac Classic, Heliobond; Monobond Plus, Ivoclar Vivadent). The two abutment teeth were reprepared and the provisionals were adapted.

Extraction with the Benex system

Due to a vertical fracture visible only after the removal of the old restoration, the lateral incisor 12 had unfortunately to be removed. To perform the extraction as minimally invasively as possible, the Benex system (Benex, Lucerne, Switzerland) was applied, as it allowed an extremely careful and predictable extraction.

Once the tooth was extracted, a lot of granulation tissue had to be removed and finally the socket was cleansed with the aid of curettes and rinsed with neomycin solution (Fig 2-5-6).

Ridge preservation

After the extraction and cleaning of the socket, a xenogeneic bone substitute (Bio-Oss Collagen, Geistlich, Wolhusen, Switzerland) was inserted in combination with a subepithelial connective tissue graft harvested from the palate, to perform a ridge preservation (Fig 2-5-7).

Endodontic treatments and placement of a ball attachment

The second premolar was shortened and endodontically retreated to receive a cast root cap with a ball attachment later during the final treatment phase. For a better retention throughout the provisional phase, the questionable first premolar received a direct composite-based ball attachment to keep the costs as low as possible and at the same time allow for a better retention of the provisional (Fig 2-5-8).

Indirect mock-up and eggshell provisional

In order to visualize the final treatment outcome and also its potential limitations, the wax-up had to be transferred into the patient’s mouth, as now the old and overcontoured restorations were removed there was sufficient space to fabricate an indirect mock-up for both the maxillary and mandibular arches in the dental laboratory (Fig 2-5-9).

Based on a silicone index of the wax-up, a classic acrylic PMMA (75% Dentin A3 and 25% Enamel High Value, New Outline, Anaxdent, Stuttgart, Germany) was pressed onto the isolated cast, to fabricate the indirect mock-up that served at the same time as an eggshell provisional. This type of acrylic was used as it was later on easy to reline and adjust to the actual intraoral preparation.

As indicated in the wax-up, a small buccal flange pink acrylic (34 Original Pink – AESTHETIC BLUE, Candulor, Glattpark, Switzerland) was added to compensate for the uneven length of the mandibular incisors and the position of the teeth in front of the ridge.

Finally, at this time point in the treatment phase and for the first time, the patient was able to see and visualize the potential outline of her new restorations (Fig 2-5-10).

Relining of the eggshell provisionals

The eggshell provisionals were now clinically relined and adjusted to the actual clinical situation. To achieve a long-term stable provisional, the same material was used for the relining as for its fabrication (Fig 2-5-11).

Amalgam replacement and direct composite build-ups in the maxillary arch

Under rubber dam, the amalgam could be safely removed and pretreated. The composite build-up (Tetric Classic, Ivoclar Vivadent) was guided by transparent silicone keys (Memosil 2, Kulzer) that reflected the diagnostics and made the build-up extremely predictable and efficient (Fig 2-5-12).

Crown lengthening

The diagnostic mock-up was transformed in to a thermoplastic surgical stent for the localized crown lengthening of teeth 11, 21, 14, and 15. Displaying the ideal pink and white proportions, the surgical stent was used to mark the needed repositioning of the buccal soft tissues. After local anesthesia (Ubistesin Forte, 3M), a buccal mucoperiosteal flap was raised with distal releasing incisions. The mock-up (ie, surgical stent), was then used to mark the necessary amount of bone to be removed buccally. The marking was performed with a sterilized round bur, and the marked buccal Part was thereafter removed with the same instrument and a chisel, assuring careful exposure of the buccal root surfaces of the teeth. The root surfaces were then polished with specialized periodontal diamond instruments (Perioset, Intensiv, Montagnola, Switzerland), and the flap was apically repositioned and sutured (Dafilon, 6.0 sutures, B. Braun Melsungen, Melsungen, Germany). During the initial healing, the patient was instructed not to clean the operated area with toothbrush or dental floss. She received a chlorhexidine solution for daily disinfection until suture removal. After the suture removal, further healing and maturation of tissues was allowed for another 3 months prior to continuation of the restorative phase (Fig 2-5-13).

Surgical evaluation of distal Part of abutment tooth 34

As the intraradicular defect and distal pocket were pronounced at tooth 34, a minimal interdental flap was raised. The distal Part of the root 34 was inspected for fissures or fractures, and the granular tissues were carefully removed. No fissure or fracture was found therefore the root surface was gently cleaned and the area disinfected with a chlorhexidine solution. Thereafter, the flap was repositioned and sutured. The healing was uneventful and the prognostics of the tooth re-evaluated to be on the safe side for a long-term provisional anchorage (Fig 2-5-14).

Conditioning of the pontic

Prior to the prosthetic replacement of missing tooth 12, the gingival area in the pontic region was shaped (ie, conditioned according to the desired emergence profile of the restoration). The conditioning was performed in order to shape the soft tissues into an “ovate-pontic-like” shape and, hence, to allow for a natural emergence profile of the pontics.

For the conditioning, a flowable composite (Tetric Flow, Ivoclar Vivadent) was applied in a stepwise approach to the basal region of the provisional pontic, inducing pressure to the soft tissues in the edentulous area and thereby shaping of this region. This procedure was repeated three times at intervals of 8–10 days until the desired shape of the pontic area was achieved (Fig 2-5-15).