By Dr Su Yu-Lung and dental technician Shih Tsai-Lieh
For some, a gap is a distinctive feature. Others want to close the gap of a pronounced diastema between the two central incisors in their upper jaw for cosmetic and/or phonetic reasons. In such cases, a disease involving the hard tissue of the teeth is not the reason for treatment. Therefore, minimally invasive procedures are absolutely essential for such purely cosmetic restorations.
In addition, preparations in enamel are beneficial in terms of the adhesive bond, and for clinical long-term success. The restorative material should be able to reproduce the color and character of the natural hard tooth substance in a limited space in order to be able to achieve a harmonious morphology, despite the low tissue removal. In the following case study, dentist Dr Su Yu-Lung (Pin Wei Dental Clinic, Hsinchu, Taiwan) and dental technician Shih Tsai-Lieh (ChuangYi Dental Lab, Changhua, Taiwan) show how they were able to work together to close an unwanted gap in the esthetic zone with fine-structure feldspar ceramic.
Case study
A 30-year-old patient presented a pronounced diastema between the two anterior teeth in his upper jaw. He was dissatisfied with the aesthetics and wanted the gap to be closed. A previous orthodontic treatment had not produced the desired results. The clinical examination revealed narrow central incisors that were positioned in a slightly flared lateral position and tapered sharply in an incisal direction. The diastema was approximately 2mm wide in the marginal region, and widened successively to 6mm in the incisal direction. In order to close the gap, the practitioner and patient opted for a minimally invasive restoration using feldspar ceramic veneers fabricated on heat-resistant stumps, while simultaneously giving teeth 11 and 21 a full morphology. To enable the aesthetic work to be carried out in a very confined space, the dental technician selected the fine-structure feldspar ceramic system VITA VM 9 for layering.
Preparation and tooth shade determination
For the minimally invasive preparation, only slight chamfers were created cervically; the vestibular expansion was recontoured minimally, and the incisal area was shortened moderately. Retraction threads were placed to achieve a precise impression with A-silicone. In order to ensure basic colour harmony between the restorations and the natural hard tooth substance, the tooth shade was determined using the VITA Linearguide 3D-MASTER, which reproduces the entire tooth colour range using 26 natural tooth shades. In two systematic steps, the VITA Valueguide 3D-MASTER was used to determine the brightness from zero to five in the first step. This was followed by matching the colour intensity and shade with the corresponding VITA Chroma/Hueguide 3D-MASTER. The selected shade tab 3M2 was finally photographed intraorally for orientation in the laboratory. Based on the tooth shade determination, a layering pattern was also created on the patient. This was followed by taking an impression and fabricating the temporary restoration.
Fabricating the model and layering
For fabricating the veneers, a model with gingival mask and heat-resistant stumps at 11 and 21 was produced based on the impression. In the preliminary layering, the mesial edges were built up with a mixture of EFFECT LINER 2 (beige) and 6 (green-yellow) to support the base tooth colour in the enamel-free area. After an initial firing, the dentine core was layered with BASE DENTINE 3M2 (70%) and WINDOW (30%). After refiring, the incisal area was created with an alternating layering of EFFECT ENAMEL 7 (orange translucent), 9 (bluish translucent), 10 (blue), and 11 (grayish translucent), and the cervical area was intensified using SUN DENTINE 2 (light orange).
After fixing the intermediate result with another firing, the upper third of the restoration was covered with ENAMEL LIGHT, and the core of the incisal area was modified with EFFECT PEARL (shade in pastel yellow) in order to reproduce the effects of a youthful tooth structure. After the final enamel firing, the delicate restorations were carefully finished and polished using fine-diamond instruments, which proved easy, thanks to the fine-structure feldspar ceramic. Finally, the two veneers were finished with the glaze firing.
Integration and conclusion
The wafer-thin restorations were tried in with glycerine gel. All parties were extremely satisfied with the results, and the restorations were finalised by cleaning the bonding surfaces, etching with hydrofluoric acid and silanising. This was followed by phosphoric acid etching of the enamel areas and fully adhesive cementation of the restorations with a composite cement. After light-curing and removal of the excess, highly aesthetic restoration results that harmonised with the natural hard tooth substance of the adjacent teeth were achieved. Despite preparation limited by the enamel, and the requirement for a minimally invasive procedure, natural and lively-looking restorations made of fine-structure feldspar ceramic were created in an extremely confined space. The patient was very happy with his new smile.
Published in Dental Asia May/June 2022 issue.
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