Key to success in Esthetics Dentistry

Finishing is the protocol of conditioning a surface and progressively reducing the scratches of the top most layer of the restoration.Polishing in case of composites is a rearrangement of the surface molecules so as to get a mirror like reflective surface.Finishing involves shaping, contouring, creating subtle characteristics (lobes and embrasures) and margination. The goals / purposes of this procedure is :

- To create a physiologic contour which renders the restoration surface and margins less likely to accumulate plaque.
- To increase wear- and discoloration resistance of the composites.
- Improve tolerance of periodontal tissues to these restorations.
- Provide the composite with an appearance that closely matches the tooth.
- Finishing is a precursor to Polishing Optimal finishing protocol ensure the right polish or lustre.

Timing : When to do -Finishing and polishing are usually conducted during the placement appointment as it is essential to remove all the excess material from the body and the margins of the restorations.Ideally, the procedure should be performed few days after the placement, reasons being -
Resins exhibit a different shade after rehydration.
Obtaining a marginal seal is better after the composite has undergone water sorption. Immediate finishing would cause cracks and subsequent increased wear of composites.

Action : All finishing and polishing procedures entail an action of abrasion or cutting. The abrasion could be involving only 2 surfaces - the abrasive and the restoration or it could be a 3 body abrasion wherein pastes or slurries are used along with the abrasive to obtain a polish. The basic philosophy however remains the same. Progressive reduction in the size of scratches as the corresponding size of abrasive particle is reduced. Before the procedure - certain aspects that have to be borne in mind include

1) The composite material being used - Composite resin restorations present a unique polishing problem because they are composed of a relatively soft polymeric resin and hard filler. Polishing may result due to unequal wear rates of the resin and filler, leaving ‘valleys’ between filler particles. These valleys are very apparent in hybrids (which still look and feel rough) and less apparent in microfills and microhybrids (appears glossy).Microhybrids tend to appear shiny and smooth but cannot be polished as easily as the microfilled. 2) Use of moist and dry polishing - Moist polishing should be preferred to avoid heat built up and to protect pulp insult. The coolant avoids charring of microfilled resin matrix. It can be done at moderate speed on airmotor / micromotor. Dry polishing should always be done on slow speed with little more pressure (especially DFS Buff, Buff discs), every grit disc should be washed before proceeding to next to remove the smear layer which may mix with subsequent discs leading to an unpredictable lustre. 3) Check of polish - polishing should always be checked by dry air for lustre and gloss.

If the look is dull reasons could be :
- use of hybrids with no microfill
- charring or overzealous dry polishing
- patches of top layer devoid of microfill
- improper protocol of finishing

Overheating / burnout / charring of superficial layer due to dry, heated polishing can cause high polymerization conversion of resin matrix and filler causing them to give a dull appearance. Then reflectivity goes down. This can be rectified by removing an entire layer and replenishing it with a new one. Follow gentle finishing and polishing protocol to get the gloss back.
Composites require strict maintainence and this should be explained to the patient. Every 3 months a check up should be carried out.

4) Maintainence - coloured mouth rinses, chewing habbits, coloured medicines on a long term basis should be avoided. Sequence to be followed for a common class lll restoration involving a central incisor would be -

1) Palatal surface - The shape of the finishing point should conform to the surface that it is to be worked upon. This ensures the desired contour and also offers a convenience in the procedure. Round / football shaped burs and points should be used on this surface. Dry finishing on this surface allows to discern the difference between resin and the tooth. The points can be moistened / lubricated to control the heat build up. This reduces the risk of having white lines on the margins.

The movement must be from the restoration to the tooth to reduce the gross excess of the material and to replicate anatomy without abrading the tooth surface.

Special abrasive rubber points and silicon coated points are suited for palatal anatomy and its smoothening. Fluted football carbide burs are recommended. Discs are difficult to use on the palatal aspect.

2) Facial surface - With the similar logical sequence as palatal.Examine the tooth from an incisal and from a profile view to detect overcontouring or undercontouring in a specific area. Complete finishing of facial surface can be performed with Flexible discs.

Natural Convexity of the surface must be maintained (contour). Intermittent abrasion is required to avoid making the restoration excessively convex or flat. The procedure calls for subtle contouring by the operator.

Long thin fine grit diamond burs, fluted (20 & 30) carbides are excellent aids to create primary, secondary and tertiary anatomy of the tooth. Coarse or fine grit diamond at slow speed helps in recreating surface textures specific to the teeth.High lustre and enhancement of surface details can be achieved by using felt wheels, cotton buffs, Buff discs or silicondioxide impregnated brushes. eg : (DFS Buff, Buffdisc (shofu), Flexibuff, Occlubrush, Vivabrush, Jiffy brush).3) Proximal Surface - Remove marginal excess and begin to form facial embrasures with a # 12 scalpel blade working with great care from the tooth towards the restorations. Scalpel blades cut microfilled resins with ease but hybrid resins poorly.Proximal surfaces are finished with Proxidisc (centrixdental) and interproximal strips (Shofu, 3M Soflex). The strips must be used apical to the contact region to preserve the contact itself. The strip should not simultaneously touch the facio-proximal and proximo-lingual angles of the restorations which would create a flat proximal surface with unwanted esthetic results. Excellent replication of the facial and lingual embrasures is achieved when the strips are positioned and pulled facio-lingually in a ‘S’ curve direction.Overzealous stripping can open up the contacts. Central portion of interproximal strips is devoid of abrasive to allow its easy entry through the contact without abrading it. Metal strips have minimal indication and need to be used with extreme care, (if at all). Proxidisc or Compodisc (Primier dental) are preffered to refine a contact.Any flash of material on unetched enamel must be removed with the scalpel blade. 4) Cervical / Gingival Surface : Finishing is done in this area by use of carbide points and with the aid of a special type of gingival retractor - the zekrya. This particular instrument conforms to the gingival form for each tooth during finishing procedures and protects it from damage.

Margination is finishing of the margin of the restoration with the tooth. It includes - removal of excess flash, overhangs and blending of polished composite to enamel, cementoenamel junction with respect to emergence profile of the tooth. Polishing : This creates the surface luster, gloss or shine. When a beam of incident light falling on the tooth surface is reflected at the same angle as that of incident light ( Angle of incidence = angle of reflection ) the phenonmenon is perceived to the eye as lustre or gloss.

On the other hand when the incident beam is scattered by the tooth, there is decrease in gloss as a larger portion of the incident beam is diffuse – scattered.

Differences in gloss between restorations or between restorations and teeth are easily detectable even in colors that are matched. In addition, high gloss reduces the effect of a colour difference because the colour of the reflected light is more prominent. In a restorative material, high gloss also lightens the colour appearance ( increases ‘Value’). After the finishing has been completed very little remains to be done for the final lustre. However, buff discs, finishing cones (Astrapol) are finally run over to achieve the result. Polishing pastes can also be used through finishing dictates the ultimate lustre.

After polishing has been completed the tooth should be evaluated for further details to match the adjacent tooth. These include :
- lustre match
- creating tertiary anatomy (surface details)
- surface texture etc.

This is what entails biomimetics ie esthetic integration of a finished and polished restoration.