Natural care for discoloration and metallic post abutments
Natural restorations of incisors is the most demanding of the dental disciplines. Cases of discoloration of the dentine and/or metallic pivot teeth/stump teeth pose a special esthetic challenge. Here, dental technicians have to choose a material mix which provides a reliable mask, but also allows for natural shading and lighting. In the following case, Master Dental Technician Show Yamamoto (Tokyo, Japan) shows how such a clinical situation can be successfully solved with the VITA YZ zirconium dioxide and VITA VM 9 veneering ceramic (VITA Zahnfabrik, Bad Säckingen, Germany). The clinical treatment and intraoral photography were carried out by Dr. Takuya Yada (Tokyo, Japan).
1. Initial situation and treatment planning
A patient came to the dental practice and expressed the desire to receive a new single crown for tooth 21. The color and characterization of the dull metal ceramic crown did not blend in well with the natural remaining teeth. The metallic crown rim was visible cervically and only partially covered with a direct composite filling. After the imperfect crown was removed, discolored dentine and a metallic stump tooth appeared. No secondary cavities could be diagnosed clinically. The radiographic examination showed a sufficient root canal treatment without periapical inflammatory signs. To mask the discoloration and metallic stump tooth, a crown framework of zirconium dioxide VITA YZ TColor in brightness level LL1 was planned. The VITA VM 9 fine-structure feldspar ceramic was selected for ceramic veneering in order to ensure a natural color and lighting.
2. Shade determination and framework fabrication
The prepared tooth stump was molded and a temporary restoration was prepared using a silicone key. The framework was first waxed against a master model and subsequently fabricated with CAD/CAM support. Special attention was paid to the tooth shade determination with the VITA Linearguide 3D-MASTER in two systematic steps (brightness + shade intensity and shade tone). The result was verified by a digital three-point measurement with the VITA Easyshade V. "I think the combination of visual and digital shade determination contributes to the precision of the final shade information," Yamamoto said, emphasizing the importance of this step. 3M2 was finally determined to be the base shade. A polar eyes filter, which eliminates reflections, was used to visualize characterizations and internal effects.
3. Veneering step by step
To reproduce the basic shade on the zirconium dioxide framework, a mixture of VITA AKZENT Plus EFFECT STAINS 5 and 3 (both orange) was initially used. After the firing, it was layered with VITA VM9 BASE DENTINE 3M2 in a similar way to the specific base shade and cervically individualized with EFFECTLINER 6 (green-yellow), 2 (beige), and 3 (brown), CHROMA PLUS 3 (light orange-brown), green-brown EFFECT CHROMA 10 (EC10) and GINGIVA G2 (orange-pink). After the first dentine firing, 3M2 and TRANSPA DENTINE 3M2 were veneered and combined with SUN DENTINE 3 (orange-red), light ENAMEL, EC10 and 3 (light yellow), blueish EFFECT ENAMEL 10 (EE10) and neutral EFFECT OPAL 1 (EO1). After the second dentine firing, whitish characterizations were created with fine vertical and horizontal lines using different INTERNO STAINS. The melt was finally layered from a mixture of NEUTRAL, WINDOW (WIN), EC 1 (white) and numerous EFFECT ENAMELS.
4. Finalization and treatment result
In order to be able to create the ideal morphology of the crown and shape of the soft tissue, a fixation mold was made in the course of the clinical try-in. Based on this mold, a new master model was made with the light-curing VITA SIMULATE preparation material as a stump material on 21, in order to definitively check the crown shape. After a minimal cut back, the dentine core was modified with 3M2, the melted material with EO5 (dark violet) and a mixture of WIN with EE7 (orange translucent). The shape and surface texture of the adjacent incisors were finally created with diamond tools. The treatment results showed a natural and vivid single incisor crown that is integrated harmoniously into the esthetics.