Restoration of aesthetics with metal-ceramic crowns (Case presentation) (58 )

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Restoration of aesthetics with metal-ceramic crowns

Based on a friend’s referral, a gentleman in his sixties reported to our clinic with the following requests:

Over the years several of his teeth had to be extracted, which rendered his chewing laborious and compromised aesthetics.
He wanted to have his missing teeth replaced with implants but on account of his limited financial means and fears, he wanted to keep the number of implants to a minimum.
He was thinking of a removable solution.
He wanted to have his old crowns replaced with metal ceramic crowns to restore aesthetics.
He desired to be able to chew properly and have sumptuous meals again (restoration of the masticatory function).

Before

After

Treatment phase 1 (5 workdays)

Installation of implants, root canal treatments, fabrication of provisional crowns.
At the first encounter the condition of the teeth and the periodontium were thoroughly examined. Taking into account our patient’s requests we agreed on the following treatment plan, having drawn his attention to the possible risks:
All his teeth will receive a crown. The upper and lower free-end edentulism will be restored with one implant each, so that a removable denture will not be necessary.
This was a compromise seeing as he wanted no removable denture, but was also for a minimum number of implants. (In such a case installing even 2 implants per quadrant would have provided better stability).

In the first treatment phase a CBCT (Cone beam computed tomography) scan was taken for the 3 dimensional examination of residual bone mass prior to the installation of the implants. Based on the scan, the implant surgery had no impediment. Besides the installation of the 4 implants, several of the remaining teeth needed to undergo root canal treatment before crowns could be mounted on them. These treatments were also carried out in these 5 days. For the time of healing the root canal treated teeth would be provided with long-term provisional crowns to protect them and repair aesthetics.

The long-term provisional crowns are fabricated by the dental technician with a few days’ turnaround based on the impression taken of the teeth. In case of several months’ healing time, long-term provisional crowns are applied on account of their durability. The chair-side provisional crown (crown made using the Scutan method) is not as durable, strong and aesthetic as the provisional crown fabricated at the dental laboratory.

Intraoral radiograph following root canal treatments featuring the free-end implant with the gingiva former

Treatment phase two (10 workdays)

The fabrication of metal ceramic crowns for natural teeth and the implants installed.

Following 6 months’ healing time the permanent metal ceramic crowns for implants and natural teeth were ready to be prepared. This requires 10 workdays’ lead time for the dental technician to deliver superior workmanship and work out the minor details of the teeth to an “artistic” perfection. If the dental technician is short of time and the recommendations for treatment times are not observed, he cannot focus on the details and this may compromise aesthetic results. Please observe the number of treatment days at all times for the best possible results.

Once the old crowns were removed and the teeth prepared, the gingiva formers were removed from the implants and precision impressions were taken of the teeth and the implants. The tooth preparations were fitted with immediate provisional crowns (using the Scutan method) to protect them and repair aesthetics for the interim period. Following impression taking a gnathological treatment (viz. an instrument-aided bite registration) was conducted for the technician to see the exact position of the jawbones in the articulator to ensure the correct occlusal position of the temporomandibular joints.

Articulator: the articulator is a dental instrument reproducing the movements of the mandible and the maxilla in the correct positions of the temporomandibular joint, “mimicking the patient’s head” in the dental laboratory, as it were, without the patient actually being present. The articulator can execute opening-closing, lateral and forward (propulsive) and backward (retropulsive) movements.

Amann Girrbach Artex articulator

Trial fittings for fabricating metal-ceramic crowns:

During the trial fitting of the framework, the precision impressions and the metal framework of the crown are verified for accuracy and all tooth restorations must fit the master cast seamlessly.
At the trial fitting of the matte teeth the crowns are almost finished with the ceramics already sintered onto the metal framework with a matte finish. This trial fitting allows a closer verification of occlusion (function) and the shape and colour of the crowns, the centre and smile lines, in other words, aesthetics (trial fitting for aesthetics).

When fabricating crowns, several days may elapse between the different trial fittings, during which the dental technicians are working on the tooth restorations in the background.

Following the trial fitting of the matte teeth, if no adjustments are necessary, the dental technician brings the crowns to completion by giving them a glossy finish (glaze) and makes them ready for gluing on.

The permanent cementing of the crowns is a meticulous process occasionally requiring anaesthetics. Anaesthetics often hinder the “fine-tuning” of occlusion as the patient does not have a precise sensation of the height of the new crown or bridge, which may necessitate another appointment for the dentist to check and adjust occlusion.

Following the permanent cementing of the crowns and adjustment of occlusion our patient was moved to tears when he explained that his smile had never been as charming before and that he was immensely happy with his new teeth.

He was advised on the importance of home cleaning and regular check-ups and was shown the accessories of home cleaning and their use (interdental brush, dental floss, Super Floss), all of which are essential for the long-term success of replacement teeth.

The finished upper metal-ceramic bridge on the master cast:

Shoulder preparations and the implant abutments. The different shapes of the tooth preparations are due to the great extent of crowding and tooth inclination