Sealants, pit and fissures

Glass—Ionomer Cement. The glass—ionomer polyelectrolyte system was developed primarily as a restorative for anterior teeth and erosion cavities a general cement a cavity liner and a base, pit, and fissure sealant (27,43—48). 

Restoratives. Polymer reskis were iatroduced as tooth restorative materials ki the early 1940s. These materials can be classified as unfiUed tooth-restorative reskis, composite or fiUed restorative reskis, and pit and fissure sealants. 

R.M. Puppin-Rontani, M.E. Baglioni-Gouvea, M.F. de Goes, F. Garcia-Godoy, Compomer as pit and fissure sealant effectiveness and retention after 24 months, J. Dent Child. 73 (2006) 31-36. 

Glass-ionomers not only release ions, but are capable of taking them up. Studies have shown that cements exposed to natural saliva take up calcium and phosphate ions, and develop a surface of significantly increased hardness [121]. Also, when used as pit and fissure sealants, they interact with saliva to form a substance with increased content of calcium and phosphate that is considerably more resistant to cutting with a dental drill than the original material. Under these circumstances, the cement had become transformed into a material with enamel-like optical and mechanical properties [122]. This observation is the basis of the development of glass-ionomer type materials with even further enhanced bioactivity, the so-called glass carbomers, which are discussed in Chapter 8. 

The ability of glass-ionomers to form a natural adhesive bond to the surface of the tooth is one of these material s most important clinical advantages. They were originally prepared from poly(acrylic acid), a substance chosen because of its use in the zinc polycarboxylate cement, a material known to adhere to the tooth surface [123]. The advantages of adhesion by these materials were apparent right from the start, when they were used for the repair of cervical erosion lesions and as pit and fissure sealants [124,125]. 

J. Avinash, C.M. Marya, S. Dhingra, P. Gupta, S. Katana, Meenu, H.P. Bhatia, Pit and fissure sealants an unused caries prevention tool, J. Oral Health Comm. Dent. 4 (2010) 1-6. 

E. Barja-Eidalgo, S. Maroun, B.H. de Ohveira, Effectiveness of a glass ionomer used as a pit and fissure sealant in recently erupted permanent first molars, J. Dent. Child. (Chicago) 76 (2009) 34-40. 

Enhanced bioactivity conventional glass-ionomers (glass carbomers) are intended for use in the same range of applications as conventional glass-ionomers, ie, liners and bases, full restorations of various types, and pit-and-fissure sealants. Because of their similarity to conventional glass-ionomers, it is considered that these materials wiU prove useful in the restoration of primary dentition [15],... 

There have been pubhcations on the effectiveness of glass carbomer as a pit-and-fissure sealant. In one [16], the study compared glass carbomer with a resin-based sealant in 48 teeth in 24 patients. After 6 months, both materials showed 100% retention and after 12 months, they both showed 75% retention. This showed that in terms of one important requirement of fissure sealants, namely retention, the glass carbomer performed quite well. However, further work is necessary to establish whether the enhanced bioactivity confers any further or longer term benefits by way of caries inhibition. 

Beun S, Bailly C, Devaux J, Leloup G (2008) Rheological properties of flowable resin composites and pit and fissure sealants. Dent Mater, 24, 548-555. 

A variety of sealants have been explored or developed (168), with many people having one or more applications of a sealant. Sealants are vital for promotion of adhesion, which significantly reduces caries formation (169-177). Pit and fissure sealants are covered under the American Dental Association (ADA) Acceptance Program. These materials are used to seal high caries-susceptible pits and fissures of the deciduous and permanent molars, and also to seal microspaces between the tooth and restorative materials, enabling these materials to adhere firmly both to prepared cavity walls and to other restoratives. They provide dental pulp protection and protection from secondary caries formation. 

Preventive dental sealants, used to seal the susceptible areas of teeth, are classified into pit and fissime sealants and smooth simface sealants. From a material science perspective, pit and fissure sealants can be further classified iuto resin sealants and GI cements. Preventive dental sealants are usually placed onto molar teeth of young children who are at high risk for caries development. 

Pit and Fissur Sealants. Resin sealants consist of a free-radical polymerizable monomer mixture, having a viscosity low enough to penetrate easily into narrow pits and fissures, capable of being cured to a hard and durable sealing material. BisGMA, urethane dimethacrylate, and other methacrylates are very popular as monomers for resin sealants, along with other monomers, to lower... 

Modern resin-based restorative materials used in stomatology originated with the invention of the so-called Bowen s monomer and the introduction of composites [142]. This monomer is known as BisGMA, a label easier to use than chemical name of 2,2-bis[4-(2-hydroxy-3-methacryloyloxypropoxy)-phenyl]propane.Today, both unfilled and composite resins are widely employed in dentistry—as binding agents, pit and fissure sealants, direct filling materials, orthodontic adhesives, and resin cements [143]. 

Pit and fissure sealants (12) used as caries preventive treatment for filling deep fissures in posterior teeth, primarily deciduous molars, are rather popular despite the controversy on the economic efficacy. The sealants now in use are composed of methyl methacrylate, Bis-GMA and/or urethane methacrylate mixtures. They are applied to phosphoric acid-etched occlusal surface in a very fluid state to flow into the surface (Fig. 11), and cured by U.V. or are self curable. They attach to the enamel by mechanical locking into the etched surface rather than by adhesion. 

Figure 11. Cured pit and fissure sealant in fissure of molar tooth showing flow of sealout completely into the fissure.

Until recently, only long wave ultraviolet light curing systems (320 - 400 nm) were used. The first of these was a pit and fissure sealant which was reported in 1970 (1). This was followed by a composite restorative in 1973 (2). Shortly thereafter, this material was slightly modified for use as an orthodontic bracket adhesive. 

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