cosmetic dentistry_ beauty & science

_The composite restoration is the basic foun- dation of the general dental practice. Countless composites are placed by dentists every day. Through the science of adhesive dentistry, these restorations can be conservative and provide long- term service. With time and function some break- down may occur, usually at the margin of the resto- ration, the interface between the tooth structure andcompositeresin.Inmanycases,whilethemargin shows localised breakdown, the rest of the resto- ration remains intact. The dentist is then faced with thedecisionofreplacingorrepairingtherestoration. In the days before adhesive dentistry, when an amalgam margin began to break down, the entire restoration was soon compromised. There was no tooth–amalgambondorsealtopreventtheleakage and percolation of saliva, bacteria and bacterial products into the area under the amalgam and the adjacenttoothstructure.Thisenvironmentallowed bacteria to thrive, creating further breakdown and secondary caries. With the advent of adhesive dentistry, leakage is nolongeramajorconcern.Eveninsituationswhere the restorative margin has become defective, the bulk of the restoration is still sealed against bacter- ial challenge. It is, however, important not to leave these margins open over the long term. With time, there can be further marginal breakdown and sec- ondary decay around the perimeter of the restora- tion. The dentist should not leave the restoration until it becomes unsalvageable and must be re- placed entirely. With today’s technology and ma- terials, there are tools to address the situation proactively at an early stage, before more extensive treatment becomes necessary. This approach is the perimeter preparation. _The ultimate wish list What tools are needed to repair and restore the defective margins of a composite resin restoration? First, there must be an excisional instrument (bur) thatisconservativeandminimallyinvasive.Thisbur should access marginal decay with minimal tooth removal.Second,therestorativematerialmustflow easily into all the irregularities of the perimeter preparation. The typical preparation is very narrow. It may also be long and convoluted, following the defects at the margins of the restoration and the surrounding tooth. The dental material of choice is a flowable composite resin, which can easily pen- etrate the intricate geometry of the narrow prepa- ration without bubbles or gaps. The ideal material should have strength and wear resistance to with- stand all oral forces. It must be radiopaque to allow for monitoring of treated sites. Additional features to this ultimate wish list are plaque resistance and remineralisingproperties,topreventfutureperime- ter breakdown. The ultimate wish list is no longer dental science fiction. These tools, materials and techniques are available, as discussed below. _Fissurotomy Bur TheFissurotomyBursystem(SSWhiteBurs)was developed to detect and remove incipient decay in enamelproactively(Fig.1).Theshapeandsizeofthe Fissurotomy Bur are designed specifically for treat- ing early pit and fissure lesions. The head length is2.5mm,allowingthedentisttocontroltheburtip to cut just below the amelodentinal junction and 26 I I technique _ perimeter preparation cosmeticdentistry 2_2013 Fig. 1 Fig. 2 Fig. 1_The Fissurotomy bur (SS White) is designed to conservatively remove incipient decay in enamel. Fig. 2_Beautifil Flow Plus (SHOFU) combines the “healing” of giomer science with the handling and adaptability of flowable composites. The perimeter preparation Author_Dr Fay Goldstep, Canada