In aesthetic dentistry there are two factors that drive the integration of a restoration with the adjacent teeth: the shade and the shape. The shape is the most important factor both in direct and indirect restorations. In posterior teeth, the main occlusal sulci and cusps predict not only function, but also the natural aesthetics of the restoration (Essential Lines).
In the anterior teeth the outline silhouette, light reflective areas, surface texture and gloss are the keys to a natural shape. In this article we will describe the Essential Shape guidelines for a natural direct composite restoration, and describe some clinical examples of tooth shape modification.
In this case we can see two different shape outcomes in a ceramic veneer try-in of the central incisors. Changing the shape from square (top) to oval (bottom) we can improve the harmony of a smile.
Shape modification after a direct composite resin restoration. An old restoration on tooth 11 had a triangular shape, while the natural tooth 21 had an oval shape. The restoration was replaced to improve the the shade and internal anatomy, as well as the shape, thus obtaining a well-proportioned outcome.
Details of a tooth surface with very little texture. This can happen due anatomic factors or by surface wear.
Usually, the more aged a tooth is, the smoother the buccal surface.
Details of a tooth surface with a rich texture. Usually, the younger the tooth, the more textured the buccal surface.
We can define the anterior Essential Shape in 4 steps:
0 – Recognize the outline silhouette
1 – Main shape (primary anatomy)
2 – Surface vertical and horizontal macro texture (secondary anatomy)
3 – Surface horizontal micro texture (tertiary anatomy)
The primary anatomy is the main factor of the shape. It is mostly influenced by the highly-reflective lines that divide the buccal reflective surface, which is mostly flat, and the shadow area at the sides that round into the proximal areas.
The primary anatomy can be different, depending on the patient. Usually the main shapes that can be found, from left to right: triangular, oval and rectangular.
To define the primary anatomy, we should look for tree factors that will give us the contour of the tooth:
– angle lines (highly reflective areas)
– incisal angles and embrasures (usually the distal angle is more rounded that the mesial one)
– buccal contour (tree inclination planes – cervical, medium and incisal)
Secondary anatomy of a natural tooth.
The secondary anatomy is correlated with the vertical and horizontal macrotexture.
The vertical macrotexture is usually more obvious with the V-shaped grooves. They are more opened in the incisal and going more narrow to the cervical.
The horizontal macrotexture is characterized by horizontal grooves usually located in the cervical and middle third of a tooth.
Tertiary anatomy of a natural tooth.
The tertiary anatomy is correlated with the thin horizontal microtexture, usually called perikymata. These are usually more visible on the cervical/medium thirdor in the deepest part of the V-shaped grooves.
Primary anatomy clinical steps:
– Define the angle lines (highly reflective areas) with a pencil and then round them with a polishing grain disc (SofLex, 3M) in a 45 degrees direction.
– Round or accentuate the incisal angles with a polishing grain disc (Sof-Lex, 3M).
– Correct the buccal contour on the three inclination planes – cervical, medium and incisal with a polishing grain disc (Sof-Lex, 3M)
Polishing discs come with different grains (Sof-Lex, 3M), and can be used in the polishing and finishing steps.
From the more coarse one to the lower coarse one, they can be used as we need to remove more or less composite resin. The lower the grain, the more polished the surface.
The secondary anatomy is especially related to the vertical macro texture and more visible with the V-shape grooves. The burs used for the macro and microtexture should be handled with gentle pressure and slow speed.
Burs used for macro and micro texturization (Finishing Style, Komet powered by Styleitaliano). In this kit, the most used bur is the perio-set 831-204-012. This but is used at low RPM.
Tertiary anatomy. To create the tertiary anatomy (perikymata) we should use a thin grain bur (831-204-012, Komet) in a horizontal movement at slow speed, creating some thin lines in the composite surface.
To soften the composite resin surface and create a glossy surface, some rubbers or spiral discs can be used (SofLex Spiral Diamond, 3M). Usually this spiral discs come in two grains. The first one is yellow, and is a prepolisher. The second one is the pink one, and makes the surface glossy. Both spirals should be used with water for easy, fast and long-lasting gloss
For a shiny surface, polishing paste and a soft felt can be used. Just a small amount of low grain polishing paste (Diashine, USA) can be added on top of the composite surface after using the abrasive discs. With a soft and extra-thin felt (Lucida, by Diashine powered by Style Italiano) the composite can be finally polished with soft, gentle, slow and round movements.
Aspect of the smooth, shiny and glossy surface of the composite resin restoration after polishing with the Lucida felt star.
Initial situation of an old composite resin restoration. The patient wanted to replace it with a new one, better adapted, with a better shade and mainly with a better shape.
Shade matched with the VitaPan Classical A2.
Remaining dental tissue after removing the old composite.
Etching of the enamel with phosphoric acid for 30 seconds. A metal strip was used to protect the adjacent teeth.
A miller matrix was placed from the palatal to allow us to create a palatal composite surface. No wax-up was used in this case.
After creating the palatal wall, a convex sectional matrix (Polydentia) was placed to create the inter-proximal surface and contour using the same enamel A2 shade. (Filtek Supreme, 3M).
After the distal contour was also created, the restoration is ready to be filled.
As the adjacent and natural central incisor is not very opaque, a body opacity was used in the middle and incisal third to recreate a natural optical effect (A2 body, Filtek Supreme XTE, 3M).
Small amounts of white and orange stains were used in the incisal edge to mimic the internal effects of the natural tooth.
Final result of the direct composite resin restoration. We can observe the natural integration of the restoration and the similar shape fo the adjacent central incisor.
Initial situation. Young patient with an old composite restoration at tooth 11 came asking for a better restoration in terms of shade and shape integration.
After removal of the old restoration, a smooth bevel was created to obtain better aesthetic integration.
The shape of a restorations can be defined in two ways: by the finishing procedures and/or by adding material to give the desired contour and volume of the composite resin layers.
The ideal situation is to control the shape from the beginning, meaning while applying and modeling the composite resin. In this case, after the composite palatal surface was built, we could use the Unica full contour matrix (Polydentia, powered by Styleitaliano) to achieve the perfect restoration contour and outline.
Situation after the palatal enamel and inter-proximal enamel application.We can see a symmetry in the contour of the restorations and the adjacent tooth. By adding the composite resin in the right way and with the right tools we can better control the final shape of a restoration.
Final situation before removing the rubber dam and before the finishing and polishing procedures.
Final situation after removing the rubber dam and after the finishing and polishing procedures. The restoration showed symmetry with the naturale adjacent incisor.
Situation after orthodontic treatment. The patient wanted to close the cervical black spaces and reshape the central incisors.
Situation after the cervical embrasures were closed. A Single mass approach (A1, Filtek Universal, 3M) was used to close the gaps and to change the shape of the central incisors to create a harmonious smile.
In the pediatric patient, the natural shape of the teeth is very important for the kid’s self-confidence. As we all know, trauma on front teeth happens especially in children, thus leading to quite common fracture of one or both incisors. Although the best solution is to bond the broken fragment, when it is missing our mission as dentists is to give our patient a direct restoration similar to the natural tooth.
Final situation of the class IV direct composite restoration of both central incisors, made with one opacity and one shade (A1, Filtek Universal, 3M). We can see that, even without internal effects, if we give am adequate shape for the restoration, the final outcome looks very natural.
Initial situation of a patient with noticeable wear, loss of VDO, and a central diastema. Also, some teeth showed discoloration. After a functional and aesthetic wax-up, we can proceed with a mock-up to check aesthetics directly the mouth, and to get acceptance by the patient.
For the final restorations, depending on the clinical conditions, the aesthetic demand and financial situation, either a direct or and indirect approach may be chosen. Direct composite resin restorations, guided by the waxup, are a simple and predictable procedure to meet our patients’ needs.
After rubber dam placement.
On the wax-up model we can fabricate a transparent silicone index to inject or press the composite, and have a predictable shape of the restoration. Nowadays, a digital workflow allows to 3D-print this stent in soft transparent resin. It is important to test the index before starting the procedure, in order to check accuracy of the fit.
After adhesion, we can alternately protect teeth with a thin teflon tape while injecting the composite resin on the other ones, through the transparent index. We should light cure from different sides of the restoration to ensure a complete polymerization.
Final situation after the finishing and polishing procedures. A single composite shade (A1, Filtek Universal, 3M) was pre-heated at 50° C and then injected/pressed inside the index. This technique can be a solution for expensive cases, if a wax-up is available. It is highly predictable, and allows full control over the final shape of the restorations.
Initial situation of an old female patient who wanted to improve the aesthetics in the upper anterior teeth with minimal intervention.
In such situations, composite resins are an excellent solution, as they allow us to maintain more sound tooth structure, which in the future will be easy to repair, if needed. In such multiple restoration cases, working with a wax-up will help us a lot, and guide us through the procedure to get the ideal final shape. In this case, a wax-up was done and then a mock-up to preview the result in the mouth of the patient. In this particular case the patient had refused orthodontic pre-treatment.
Final situation a few months after the direct composite restorations were made. An A2 body shade was used for the restorations (Filtek Supreme XTE, 3M).
The upper right canine was lightly prepared to allow us to change the shape to that of a lateral incisor. Even with a freehand application we can get a natural and predictable result with direct composite restorations.
The goal of direct anterior composite restorations is to emulate the natural teeth of the patient. The shape is the most important factor to take care of during the restorative procedure, in order to have natural looks and harmony. The Essential Shape step by step helps us get this integration and harmony, based on the anatomical details of each patient. Even though shape is the most important factor, we should also never discard the shade and maintenance of direct composite resins to get long-term success of our treatments.
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