The fabrication of zirconia front crowns and cement-retained metal-ceramic implant crowns (Case presentation) (45)

Our male patient, 50, reported to our clinic with the following requests:

• He sought to have his missing teeth restored (restoration of masticatory function) preferably with implants.
• Restoration of aesthetics was a top priority for him so that he could feel at ease to smile again.
• With his front teeth he desires to have metal-free tooth restorations, i.e. zirconia crowns to achieve as natural an appearance as possible.
• He was looking to have a nice smile, and not overly white teeth but ones that match his age.

Before

After

First treatment session – 3 workdays (consultation, tooth extractions)

At the first consultation a panoramic radiograph was taken to examine the condition of the teeth and the periodontium. The first examination revealed that the lower left first premolar had to be removed and a few others were due for a root canal treatment. We explained to him that tooth extractions had to come first since the bone needs 3 months’ recovery time before it is suitable for the insertion of an implant. We drew up a treatment plan which the patient received with a quote included. Having conducted extensive research into the available options he clearly made up his mind as to the type of the crown he was after, and his choice fell upon zirconia crowns for front teeth but he went with conventional metal-ceramic crowns for his rear teeth. At the first treatment session the root of tooth number 34 was removed. The treatments could be resumed 3 months thereafter with the insertion of the implants.

Panoramic radiograph of the initial condition

Second treatment session – 7 workdays (instalment of implants, root canal treatments)

The second treatment session began with a CBCT (Cone beam computed tomography) scan in order to examine the residual bone mass in 3 dimensions and establish whether the missing teeth could be restored by means of implants. The sites of the lower left premolar extracted in the previous treatment session and the missing second molar behind it were both suitable for the instalment of implants. The upper left molar could not be restored without a bone graft, but since he was against a maxillofacial surgery of that scale, this tooth would be restored by means of a bridge in the next session.

A CT scan displaying the mandible. This image allows bone height and width to be examined in 3 dimensions in and the site and size of the implant can be laid out.

A CT scan picturing the mandible. At the site of tooth number 36 a bone height of 10 mm and bone width of 8.75 mm is available for the instalment of the implant.

At the second treatment session the upper left canine (no. 13) and the lower left first molar (no. 36) were root canal treated, with the ProTaper Next machine-driven endodontics treatment instrument, Raypex 6 apex locator and by means of the lateral condensation technique.

Intraoral panoramic radiograph following the root canal treatment of tooth no. 13.

 

Follow-up panoramic radiograph following the instalment of the implants and the root canal treatments at the end of the second treatment session

Third treatment session – 10 workdays (fabrication of zirconia crowns)

Following the mandatory 3 months’ healing period it was time for the fabrication of the permanent restorations. For the most part, this is the most time-consuming of all the encounters. Zirconia crowns were designed for front teeth and metal-ceramic crowns for the molars and implants. Precision impressions are taken of the tooth preparations and implants with closed-tray impression copings. A gnathological treatment is conducted involving bite registration and a face bow transfer by means of an Artex face bow.

Follow-up radiograph of the closed tray impression copings inserted into the implants

Provisional crowns are made for the tooth preparations in order to protect them until the permanent crowns are ready. Following impression taking several trial stages follow whilst the dental technician proceeds with the preparation of the crowns. During the framework trial fitting, the impressions are checked for trueness, and the frameworks of the tooth restorations are checked for accuracy and their seamless fit of on the master cast. On front teeth zirconia crowns have a white framework.

Metal and zirconia frameworks test-fitted on the master cast

The abutments of the cement-retained implant crowns as laid out on the master cast

At the preliminary trial fitting the crowns are almost complete with the ceramics already sintered onto the framework with a matte finish. At this trial fitting the patient’s bite (function), the shape and colour of the crowns and the midline and smile line can be checked again (aesthetic trial fitting).

Preliminary trial fitting on the master cast

Several days may elapse between the different trial fittings while the dental technicians are working on the tooth restorations in the background. When the crowns were permanently cemented in place, our patient left with was satisfaction. He recovered his self-confidence and feels at ease to smile again thanks to his new crowns. WARNING! Implant-borne tooth restorations require as much, if not more attention, care and follow-up as restorations retained by natural teeth. It is often thought that tooth restorations need no professional tartar removal, but this is a misbelief. There is a close relationship between oral hygiene, the quantity and quality of tartar and the long-term success of the implants. To this end, make sure to abide by the following instructions:

• Reporting for regular annual follow-up, which is also a condition for warranty.
• Professional tartar removal every once or twice a year.
• Use of dental floss (Super Floss) for cleaning bridges and a suitably sized interdental brush at least once in the evening before going to sleep.
• Thorough brushing after each meal, preferably with a soft bristle tooth brush.

Follow-up panoramic radiograph of the crowns designed for natural teeth and implants

Before

After

Before

After

The new smile

Keywords: Zirconia crown, metal-free crown, cement-retained metal-ceramic implant crown, dental implant, gnathological treatment, Artex face bow, framework trial fitting, preliminary trial fitting, CBCT(Cone beam computed tomography), Super Floss, interdental brush, ProTaper Next, Raypex 6