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A smile says more than a thousand words: Reconstruction & modification of anterior teeth

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Fig. 1: Initial situation: worn incisal edges, enlarged interdental spaces, and aesthetic shortcomings.
Ronaldo Hirata, Brazil

By Ronaldo Hirata, Brazil

Tue. 3. March 2009

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Ceramic veneers and direct composite build-ups present the two most popular treatment options in modern dentistry for modifying anterior teeth; both attain a harmonious aesthetic appearance and re-establish an anatomically correct form and proportion of incisor teeth. Ceramic veneers necessitate tooth preparation, which in most cases involves the reduction of tooth structure. Hence, ceramic veneers are categorised as irreversible dental treatments. The progress achieved in the field of dental adhesives and the continued improvement of the mechanical and optical properties of dental composites have opened up new possi- bilities in restorative dentistry. It is now possible to fully restore the aesthetic appearance and function of anterior teeth that have lost their original length due to parafunctional habits or physiological abrasion, using resin-bonded composite restorations. Careful treatment planning is, however, essential for keeping the reduction of healthy tooth structure to a minimum.

Direct composite build-ups provide a treatment method for rebuilding worn anterior teeth, if the treatment is accurately planned and performed. This is particularly important if anterior guidance has to be established or if a guard splint has to be produced upon completion of the restorative treatment. This article describes the reconstruction of anterior teeth with a nano-optimised hybrid composite material.

Case report

A male patient presented with abraded anterior teeth. The abrasion was caused by parafunctional habits, resulting in a loss of canine and anterior guidance. In addition, the aesthetic appearance was compromised (Fig. 1). As a large portion of healthy tooth structure was still present, we opted for a minimally-invasive treatment method using composite material. In addition, this method would allow us to restore the teeth with ceramic veneers at a later stage, should this become relevant.

Initial treatment planning is best carried out on the basis of digital images of the patient’s situation, providing the dentist and the dental technician in charge of producing the wax-up with all the necessary information. A silicone key was prepared from the wax-up and used to fabricate a mock-up. In addition, the silicone key provided a spatial reference for the composite build-up. The dentition was bleached before commencing the restorative treatment. As a result, a consistent tooth shade was established before the aesthetic intervention was started.

The appointment for restoring the teeth was scheduled for two weeks later—this is the minimum interval that should be observed between the bleaching process and restorative treatment, to ensure a firm bond to the tooth structure and a stable tooth shade, which is essential to accurate shade selection. As the existing restorations exhibited hardly any defects, only those portions that were close to the surface were removed.

If existing restorations demonstrate an acceptable shade and tight restoration margins, repairing them is often the best solution.

Relative isolation may be sufficient in conjunction with cosmetic treatment in the anterior region. In the present case, untreated retraction cords were used.

Two points have to be considered when restoring anterior teeth with composite materials: first, the restorative treatment should start with the central incisors, and second, the central incisor that shows the least damage, i.e. is closest to the ideal final result, should be restored first. Restoring several teeth simultaneously may lead to problems in the proximal region, such as inappropriate proximal contact areas.

The prepared surfaces were etched for 30 seconds using the total etch technique. Next, Tetric N-Bond was applied and light-cured for 20 seconds (Fig. 2). If a silicone key is sited, composite stratification is started in the palatal area, for which a translucent shade is utilised. In the present case, Bleach I (Tetric N-Ceram) was applied. The composite was placed in a very thin layer in order not to impair the subsequent reconstruction of the incisal edge (Fig. 3). After the material was light-cured for 20 seconds, the dentin core was rebuilt using a shade that offered an appropriate level of opacity and saturation. In the present case, Tetric N-Ceram A3.5 Dentin was applied and light-cured for 20 seconds. An opaque halo effect resulted. This thin visible line is produced regardless of the patient’s age or degree of tooth abrasion. The halo effect is caused by the variation in the arrangement of vestibular and lingual enamel prisms. For this purpose, Tetric N-Ceram in shade A3.5 Dentin was utilised. The same shade was also used to rebuild the dentin body. Since this material was applied in only a thin layer, light-curing for 20 seconds was sufficient to achieve an optimum depth of cure.

Next, the incisal effects were recreated using Bleach I (Fig. 4). The same shade was used for the reconstruction of the palatal surfaces. This material provides a slightly bluish translucent effect and thereby enhances the degree of translucency and accentuation in this area. After the incisal and palatal surfaces were rebuilt, Tetric N-Ceram A2 was applied to the entire surface in the vestibular region. The material was applied in slightly thinner layers in the marginal and incisal areas, to save space for the application of an incisal material with a higher degree of translucency. This method enhances the passage of light and slightly reduces the colour saturation of the basic material. Here, Tetric N-Ceram T was utilised for this purpose.

Before final light-curing, the composite surfaces should be covered with a thin layer of glycerine to prevent the formation of an oxygen-inhibited layer and to ensure complete curing of all layers including the top layer. The goal of the layering technique is to pre-empt work-intensive adjustments and to keep the shape of the restoration close to the original. Polishing discs were employed for contouring of the occlusal outline and vertical dimension of the mesial contact areas (Fig. 5).


Figs. 2–6: Tetric N-Bond adhesive is applied to the central incisor after etching with phosphoric acid (Fig. 2). The incisal edge is built up with translucent composite material (Tetric N-Ceram Bleach Incisal) with the help of a silicone key, which has been fabricated based on the wax-up. After this layer has been light-cured, dentin material (Tetric N-Ceram A3.5 Dentin) is applied (Fig. 3). After special effects have been applied, the incisal edge is rebuilt using a specially designed spatula (OptraSculpt) (Fig. 4). After the first incisor has been built up, the proximal contact areas are roughly contoured to facilitate the subsequent re-establishment of adequate contact areas (Fig. 5). The same procedure is used to build up the other teeth. After restoring the central incisors, the lateral incisors and canines are reconstructed (Fig. 6).

Tooth 21 was the second incisor to be restored (Fig. 6). The same technique used for the restoration of the first central incisor was employed. Here, particular care was given to the reconstruction of the contact areas between the two incisors. For this purpose, the restoration was first built up with shades A2 and T until contact with the first restoration was established. At this point, the build-up was light-cured, the proximal surfaces were separated, and composite material was applied from the palatal to the vestibular surface by means of a transparent matrix. After the central incisors were restored, the lateral incisors and canines were reconstructed according to the same principles. After all composite build-ups had been completed, the restorations were finished and polished. Further details may be applied at a later appointment, if desired. First, the occlusal outline and marginal ridges were finished using polishing discs. Here, it is important to pay attention to providing mirror-image symmetry. In other words, the distance between the marginal ridges of a central incisor should not only be physically symmetrical, but the distance should also be optically the same in relation to the other incisor in what is known as symmetrical virtual width. Vestibular lines and depressions can be created with spiral-shaped diamonds (Jota) and a T2 Revo R170 angled hand-piece (Sirona).

The 3-step polishing system, Astropol, allows the restorations to be polished to an optimum surface finish. Finishing is carried out with silicone finishers (Astropol, grey finishing cup) (Fig. 7). The Astropol set is used directly on the composite surfaces in conjunction with indirect water cooling (from a rotating instrument or multifunctional syringe with water spray); a polishing gel or paste is not necessary. Polishing should be performed with intermittent movements, which can be easily accomplished with silicone rubber polishers. The grey finishers facilitate the finishing process considerably. The green Astropol polishing cups are used to polish the surfaces, providing a very smooth surface finish.


Figs. 7 & 8: The restorations are polished with Astropol (Fig. 7). The surface texture is rendered visible with ceramic powder. Shortcomings and inadequacies are now easily identifiable and can be corrected if needed (Fig. 8).

In some cases, it is necessary to apply additional surface characteristics to the labial surface. A variety of options is available for this purpose. In the present case, a spiral-shaped diamond was utilised to apply irregular, frequently interrupted lines of varying depths mainly on the central third of the incisor (the lines can be marked in pencil before they are cut). The lines are clearly visible. After having been cut, they were levelled off with grey finishing tips (Astropol) without, however, eliminating them. The pink polishers (Astropol HP) were subsequently utilised for high gloss polishing. The resulting surface texture, marginal ridges, and mirror surfaces can be viewed more clearly by dusting dry ceramic powder onto the restorations. After the surfaces had been examined, the powder was removed with oil and water spray (Fig. 8). Final polishing was carried out with aluminium oxide polishing pastes.

Conclusion

Direct build-ups of composite restorations are suited, in selected cases, to re-establish the aesthetic properties and function of worn, aesthetically unpleasing anterior teeth. It is however important to select a composite that offers appropriate optical and mechanical properties. In the above clinical case, a group of anterior teeth were aesthetically restored with the Tetric N-Ceram nano-hybrid composite system (Fig. 9).


Fig. 9: Completed restoration of the aesthetic anterior region.

Editorial note: This article was originally published in Cosmetic Dentistry Vol. 3, Issue 1, 2009 and is published here with the kind permission of Ivoclar Vivadent.

Contact info

Prof Ronaldo Hirata
R. Candido Xavin 80
80240-280 Curitiba – PR
Brazil
E-mail: ronaldohirata@ronaldohirata.com.br
www.ronaldohirata.com.br

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