The step by step in finishing and polishing: anterior direct composite restorations
Although we often consider color the main challenge of anterior composite restorations, finishing and polishing procedures are the ones that let us create the shape and texture that are just as crucial, as they’re necessary to restoring all the three-dimensional features that natural teeth have.
In the direct restorative process we must follow several steps to achieve aesthetic, natural and predictable results. These steps are: planning, dental preparation, adhesion, layering and finishing and polishing.
The natural tooth is rich in small details that make all the difference in integrating the restoration when they are replicated. These details can be: length, width, proportion, length / width, contour, flat area, lobes, crests, vertical grooves, texture, wear facets, incisal edge thickness, fracture lines, periquimatias, point and contact surface, embrasures, palatine concavity and cingulum.
The details of shape and texture thus become essential to the integration of the restoration with the remaining natural teeth and smile of the patient.
First, it is mandatory identify the surface type of the patient’s natural teeth, see if there is a surface texture or just a smooth surface, without much detail. The act of observing the natural tooth becomes fundamental for us to understand what we must reproduce in our restoration. Observing the patient’s anterior teeth from various angles can give us a lot of rich information about the details of shape and texture.
When direct observation is not enough or becomes complicated, we can use some auxiliary methods of texture identification, such as silver powder or articulating paper, passing over the vestibular surface of the natural tooth. In this sense we will be able to observe the differences between zones of high reflection of light and zones of shadows, more prominent zones and grooves more or less detailed.
In case the surface of the natural teeth to be copied is smooth, the clinical process of reproduction can become simpler as we will have to go through fewer steps: details of shape, polish and hight shine surface.
When we want to have a polishing and textured tooth we can divide this procedure into four shapes: shape details, macro texture details, micro texture details and brightness.
The first step of finishing and polishing involves checking and/or correcting the shape of the tooth. The shape is responsible for the symmetrical proportion and integration of the restoration with the various teeth. To check the shape we have to observe the angle lines, which divide the plane area of a large reflection light (between the angle lines) and the shadow area, which lies outside the angle lines and is rounded.
By working in the distance between the angle lines we can create optical illusions between wider or narrower, longer or shorter teeth, maintaining the actual proportion of the tooth. So if we want to give the illusion that the tooth is narrower, we should approach the angle lines, decreasing the flat area. On the other hand if we want to create the illusion that the tooth is wider, we should move away from the angle lines by increasing the flat area.
Typically, this correction of angle lines and flat area is made with medium grain discs or with fine-grained diamond tips.
Then the contour of the incisal embrasures must be done. This contour may range from straight or curved. Usually the distal angle is more rounded than the mesial angle. In a feminine smile, the incisal embrasures are usually rounder too.
The outline of the embrasures is usually made with abrasive discs. Almost all brands that have abrasive discs provide four particle sizes identified by color. In the finishing process we usually use only the two intermediate grains (for example Sof-Lex, 3M dark orange and light orange). This is because if we use the more abrasive we can remove too much composite resin and if we use the less abrasive we only add brightness to the resin.
To finalize the details of shape, it is necessary to verify and/or rectify the vestibular contour of the restoration, respecting the transitions and inclinations between the cervical third, middle third and incisal third. This procedure is usually done with medium or fine grain diamond drills (depending on the amount of composite resin to be corrected).
Before proceeding to the details of macro and/or micro texture, inter-proximal polishing and removal of cervical excess should be done.
Interproximal polishing should be done with strips of sandpaper. These may be more or less abrasive (for example Epitex, GC) depending on the amount of interproximal material to be removed and polished.
If there is too much excess in the cervical crenellations or the need to rework these crenellations, metal polishing strips should be used. These sandpapers are also available in different abrasives (GC, Edenta, Intensive, Coltène, etc.).
Cervical excess can be removed with a #12 surgical blade (by shaving the center of the tooth out) or by an instrument itself called Eccesso (LM Arte).
After the details of shape and contour, it is advised to pass a rubber or a rubber disk on the composite resin to smoothen the entire surface.
After correcting the shape, contour and volume of the restoration, if we want to recreate a textured tooth, we should go to the macro texture details.
The macro texture can be divided into two groups: vertical macro texture and horizontal macro texture.
The vertical macro texture existent especially in the upper incisors can be called vertical grooves or “V-shape grooves”. This macro texture shows the relief made by the three developmental lobes (mesial, central and distal) and by the depressions between them (commonly called groove). These vertical grooves are usually more open in incisal and will narrow each time we walk to the cervical of the tooth, giving the “V” shape to this depression. There are usually two vertical grooves, of which the distal is usually longer than the mesial. This procedure is usually done with low-rotation fine-grained diamond drill.
The horizontal macro texture is more evident in the cervical third and in the transition with the middle third of the tooth. It consists of 2 to 3 small, very smooth horizontal grooves that lie between the angle lines. This procedure is usually done with fine grain spherical diamond drills in low rotation.
After the preparation of the vertical and horizontal macro texture, it is necessary to soften the depressions caused by the drills on the surface of the composite resin. This softening of the surface of the composite resin should be done with rubbers.
There are different types of rubbers for smoothening the macro texture, depending on the amount of smoothening and degree of polishing desired.
Several manufacturers offer rubber systems with different granulations (ex Astropol, Ivoclar). When these different granulations exist it is necessary to go through the entire polishing system, starting at the most abrasive rubber and finishing at the less abrasive rubber.
The rubbers should run through the vertical or horizontal lines previously marked with the diamond rotating tips, leaving the composite surface with a smooth appearance and with slight transitions between depression areas and prominent areas (lobes).
After smoothening the macro texture, the vertical and horizontal micro texture must be done (if present in adjacent natural teeth).
The vertical micro texture usually consists of small vertical grooves that normally exist in the middle of the vertical macro texture grooves.
The horizontal micro texture consists of thin horizontal lines that extend from the cervical to the incisal of the vestibular surface. These lines, usually called perikymata, are extremely thin and are very close to each other.
A very thin diamond tip should be used in this step. The position of the tip relative to the vestibular surface of the restoration should be about 45 degrees, using a very gentle pressure and always in the same direction (mesial to distal or distal to mesial).
After re-creating the micro-texture, the surface of the composite resin should be slightly smoothed. This softening can be done with low abrasive rubbers or with new spiral materials such as Sof-Lex Spiral (3M ESPE) or ShapeGuard (Coltène). In addition of softening the composite resin and giving it a natural look, they also add some shine to the restoration. If a natural tooth are not too shiny on the surface, or that have low gloss, this may be the last step in the finishing and polishing process.
To finish the finishing and polishing process and give to the composite resin a natural appearance of enamel gloss, it is recommended to use a low-grade (less than 0.5 micron) diamond pastes or aluminum oxide pastes. These pastes should be applied with a felt disc or a soft-brushed brush, to not scratch the surface of the composite resin. Circular movements should be made with low pressure and use low rotation (maximum of 5000 rpm).
These steps described above can be performed with water or without water. The advantage of not using water is to have a better visibility of the details. In this case, plenty of water should be used between each step to cool the tooth and clean all debris created by the instruments.
It is also recommended the use of a low speed rotating hand peace (multiplier contra-angle) for the accuracy of the details.
In this first article dedicated to the finishing and polishing of composite resin restorations we will address the “direct restorations in anterior teeth” and we intend to demonstrate the most important details in the identification of the texture and shape of the natural tooth, the step by step in the making of a natural and suitable texture and the materials necessary for its execution.
Finishing and polishing can be considered the last step in the direct restorative process. However it should be regarded as one of the most important allowing the actual natural integration with the adjacent teeth.
It is essential to obtain a smooth and polished surface of the restoration so that its chromatic stability, and surface state is as durable as possible over time.
However, for the details of shape, texture and brightness to last longer, a periodic maintenance of the restoration is necessary, where the surface and gloss state must be evaluated. If necessary, the restoration should be re-polished. This procedure can often be done during the periodic oral hygiene consultations of the patient.
Composite resins have some limitations of longevity, the use of a correct finishing and polishing technique can increase a over life composite resin restoration and reproduce the natural surface of the natural tooth.
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