By Dr Salvatore Scolavino and DT Francesco Napolitano 

The dental laboratory is confronted with the greatest aesthetic challenge whenever it comes to the restoration of a single incisor with natural adjacent teeth. In the following case, a young patient had undergone endodontic treatment of her tooth 21 (fig. 1) while all other teeth showed their natural appearance. Tooth 21 was due for replacement now (fig. 2).

Fig. 1:  X-Ray after endodontic treatment (with new crown on tooth 21 in place).

Fig. 2: The former restoration with which the patient showed up in the dentist’s practice.

To keep the natural identity, together with preserving the gingiva outline, the decision was taken in favour of a monolithic zirconia restoration, with a layered block for a full-contour crown. KATANA™ Zirconia STML (Kuraray Noritake Dental) provides for four gradational layers from „Body/Dentine“ (cervical area) to „Enamel“ (incisal aera), varying in chroma and translucency. Using this kind of milling block, it is possible to imitate the natural progression from yellowish to whitish-blue, and this in an easy manner. At the same time this way, the endodontic post wouldn’t shine through and make any aesthetic difference. On the other hand, the zirconia irradiates into the gingiva and results in a natural looking shade allover the anterior area. Furthermore for a lively and most natural-identical appeal, it was intended to individualize the crown by surface stains. With the product CZR™ FC Paste Stain by Kuraray Noritake Dental, 27 shades are available, together with fluorescence. What is essential in the front, too, is this well proven experience: All zirconia material enhances the close gingival attachment and provides for stable results of the pink-and-white aesthetics.

The dentist built up the stump 21, prepared it according to the specifications for zirconia and took the impression (fig. 3). The plaster model followed (fig. 4) and was scanned to start then the digital process. After designing, the crown was milled and tried-in at the next session with the patient (fig. 5).

Fig. 3: Impression taking after preparing tooth 21.

Fig. 4: Plaster model - the prothetic baseline of the case.

Fig. 5: Try-in of the zirconia crown in the patient’s mouth with rubber dam.

SHAPE AND COLOUR

Right when starting the case, the teeth of both jaws had been scrutinized: first for shape. Special attention was payed to the interproximale space between 11 and 21 because this area had worn out in the meantime (see again fig. 2). It was also necessary to move closer to each other the approximale margins 21/22 resp. 11/12 in their cervical-middle parts. When giving the zirconia crown its final shape, this resulted in a widely swinging outer line distally 21. For harmony reasons, tooth 11 was extended distally, too. Here, the clinician used the direct filling composite CLEARFIL MAJESTY™ Classic, shade A2 (fig. 6, 7 and 8). This nano-hybrid composite by Kuraray Noritake Dental is easy-sculpting and integrated fully with the milled crown.

It was most important for crown 21 and tooth 11 too, to create a 3D effect of the tooth structure and an age-appropriate vestibular surface texture. For this, the characteristics of the adjacent teeth and allover both jaws were examined meticulously in general and in detail. Surface burs, discs, stones, and similar instruments sophisticatedly engraved pericymatia and a groove here and there, thus accomplishing the perfect natural look.

Fig. 6: Tooth 11 before recontouring the shape distally.

Fig. 7: Finished crown 21 on the plaster model. Notice: In order to match the shape of crown 21 and close-up the margins 11/12, composite has been added in the interproximal space.

Fig. 8: Finishing the new distal outline of tooth 11.

The final colour touch was given to both teeth by surface staining: with a thin layer of FC Paste Stain measuring only 50-70 micrometers in depth, different shades were applicated. The entire range was used from yellow/orange to blue and white (fig. 9a-d) in order to provoke the effect of mamelons and other structures in all thirds of the restorations.

Fig. 9a: Definitive fitting of the restoration.

Fig. 9b: Directly after the fitting.

FINAL SITUATION

Fig. 9c: View of the lips with the restoration in place.

Fig. 9d: Natural look of the upper and lower jaws.

By Daniele Rondoni, RDT

Hybrid designing meets the functional needs in term of lower abrasiveness and higher toughness.

Step 1
Zirconia Frame (KATANA Zirconia HTML A2) cut-back designed to minic anatomical dentin structure and incisal frame.

Step 2
Application of Internal Stain.

Step 3
Completion of Internal Stain firing.

Step 4
Application of Luster, Clear Cervical and Opacious Body.

Step 5
Completion of firing.

Step 6
Completion of glaze (self-glaze) firing.

Step 7
Polishing of lingual side.

Step 8
Post-operative view.

4-Years Post-operative.

CERABIEN™ ZR
High translucent and opal porcelain for True-to-life, highly aesthetic restoration.

Blue-tinged light translucency at incisor edge of enamel was reproduced with LTx and LT Royal Blue.

Initial situation.

LTx and LT Royal Blue were used at the incisor edges to reproduce the bluish opalescence and translucency effect.

Step 1: Build-up of internal structures.

In order to reproduce the mamelon structure with stain and dentin color, Internal Stains were applied, then baked.

Step 2: Applied the first Internal Stain, then baked it.

In order to reproduce the stain in the internal enamel structure, Luster porcelains were applied and baked as a base.

Step 3: Applied the first enamel structure, then baked.

In order to reproduce the white spot and the incisor halo, Internal Stains were applied before baking.

Step 4: Applied the second Internal Stain before baking it.

To reproduce the subtle color and translucency of enamel, Luster porcelains were applied before baking.

Step 5: Applied the second enamel structure before baking it.

Step 6: Final situation.

Photos: Courtesy of Otani Dental Clinic, MDT Ryuzo Shiba and MDT Naoto Yuasa.

By Daniele Rondoni, RDT

A middle-aged patient sought dental advice because she felt uncomfortable with the aesthetic appearance of her upper front jaw, specifically regions 11, 12, 21 and 22. Additionally, she was not happy about the diastema between her upper central incisors.

Fig. 1: Initial situation.

The oral examination showed four crown regions (12-22) and revealed that all of them have deteriorated. Tooth 21 had undergone an endodontic treatment, while teeth 11 to 22 have been newly built up. Due to the deteriorated conditions, all affected teeth were taken into consideration in the planning and designing of new restorations, including the intention to close the diastema between the width-to-length-ratio for the incisors.

The best suitable material for a natural look in combination with a close gingival attachment to the restoration is, in this case, zirconia, because of its biocompatibility and gentleness to the gingival region. The KATANA^TM Zirconia series from Kuraray Noritake Dental, offers a line-up of high-quality materials combined with true-to-life aesthetics, due to its natural color gradient within the material.

Fig. 2: Preparations, showing discoloration in the cervical area of tooth 21.

Fig. 3: Occlusal view of the preparations.

Fig. 4: The four zirconia crowns after designing followed by milling.

Fig. 5: Result directly after sintering.

To achieve an even more natural-looking and aesthetic restoration, CZR FC Paste Stains were used externally on the zirconia surface.

Fig. 6: Characterization of the restoration.

As often done, Cervical 2 was used to give an orange tint to the cervical area, to accentuate even better the natural tooth gradation. For the incisal areas, Grayish Blue in combination with Value was used to enhance transparency and opalescence. Same procedure applied to the approximal areas. Mamelon Orange 2 was used to reproduce dark orange stain on the mamelons.

Fig. 7: Result after cementation of the four new zirconia crowns. Their shape and chroma blend harmoniously with the arch.

Fig. 8: The vestibular view showing natural-looking characterization.

During a period of five years, annual check-ups showed intact crowns and a healthy gingiva. Additionally, the durability of the restorations, including their mechanical and optical properties revealed no signs of deterioration.

By Japanese Dr. Shigeru Adachi, Cusp Dental Supply Co. Ltd

Initial situation

Checking of the shade (Posterior Crowns: FC Paste Stain, Anterior Crowns: Micro layered CERABIEN™ ZR)

Checking the restoration on the model

Final situation

Ceramist:

MDT Shigeru Adachi, Cusp Dental Supply Co. Ltd

MDT Adachi is a promising ceramist of the new generation, who has been working for Cusp Dental Supply Co. Ltd. since 2013. He received the Award of Excellence 2018 at QDT TECHNICAL CONTEST.

April, 2013 - Present
Working for Cusp Dental Supply Co., Ltd.
March, 2013
Graduated from the Osaka Ceramic Training Center
April, 2009 - March, 2011
Worked for Tsuruga Denatal Laboratory
March, 2009
Graduated from the Aishi Dental Technician College

MDT SHIGERU ADACHI USED KATANA™ ZIRCONIA HTML AND CZR FC PASTE STAIN FOR HIS CASE STUDY