Polishing lifelike composite
The aim of this step-by-step article is to show how easy is to obtain extremely shiny composite restorations, with rich morphology and long lasting surface stability changing just very few times the rotating instruments on our contrangle.
This article is part of chapter 10 of the book “Layers” by Jordi Manauta and Anna Salat published by Quintessence books on September 2012.
The tree rotating instruments used, from left to right goat brush (Shiny S, Micerium, Italy), felt wheel (Shiny F, Micerium, Italy) and Periocare blue ring bur (DC Pericare 831 524 014, Alicante Spain)
A sample tooth of white composite (Intensive milk “IM”, Micerium) obtaining on purpose a terrible surface after final polymerization. The color white is to obtain full visibility in this exercise.
Probably the most important step is the first one. We place in the contrangle 10,000rpm (maximum) the Periocare blue ring bur and obtain a smooth surface, trying to eliminate all the excess and uneven parts to obtain a continuous surface. The aim is to educate ourselves to achieve a “bake-bisque try in” like surface which any ceramist can teach us very precisely. This step usually is where we focus most of the time in the finishing and polishing stage.
With a sharp pencil we mark the proximal angles to define the shape of the tooth (primary anatomy).
Following the marked lines, always with the same bur, we do some pre-interproximal grinding at low speed. This step can be done in a clinical case and often we must get help with red and yellow diamond polishing strips (Intensiv). Note how the tooth changes its shape dramatically.
With the pencil we can mark the path to do some incisal characterizations (if needed) in this case we make the proximal lobes more short as in many young teeth.
After incisal grinding (with the same bur) we mark some incisal lobes division and develop them with the tip of the bur. If they need to be really sharp we can help ourselves with the red diamond strip.
In order to develop secondary anatomy (macro texture), we mark some vestibular weaves which must be sharper in the cervical and wider in the incisal, but always very smooth, we shall never see the “bur shape” marked on our restorations. To achieve this we must pass the bur from mesial to distal, applying more pressure when approaching the center of the groove and releasing it he surroundings.
With a pencil we mark the tertiary anatomy (micro texture), note that the more close and parallel the grooves are, the more natural they look.
With the same bur always at low speed, we can develop with just the tip, each one of these grooves. the more pressure we make, the deeper the grooves will be.
We use a polishing rubber tip to remove grinding debris and smoothen the surface.
After the finishing stage with the bur (which I consider to be the most important) the we start the polishing, to do this we switch to the goat brush and apply a supercharged and superfine diamond paste (Diamond Twist SCL, Premier), we spread the paste with the brush without rotation, then we start 3,000 rpm with no water, doing really slight touches otherwise extreme heating can happen and ruin something more than the restoration, and then 15,000 rpm with water.
The restoration showing a “ceramic like” appearance, after cleaning with a gauze the paste excess.
The tooth observed from a 45º degree view, shows strongly the surface characterizations and secondary and tertiary anatomy playing a fundamental role in lifelike of restorations.
When working extraorally we can use some silver powder to study shape, texture and every minimum detail of our work.