Fissure sealants

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. 

Fissure sealants are clear, low-viscosity, photocurable liquids, based on a mixture of fefrafunctional and difuncfional mefhacrylafes. Other dental photocurable materials are cements, adhesives, and denture base resins. " ... 

Studies have also shown that calcium and phosphate can be taken up from saliva [55]. Specimens that were exposed to saliva not only had an altered chemical composition in the surface, but they were also significantly harder than specimens exposed only to pure water. This showed that the calcium phosphate-enriched surfaces were mechanically different from the unmodified ones. In a clinical study of glass-ionomer fissure sealants, residual cement left at the bottom of deep fissures was found to form an enamel-like structure with time, either by ion-exchange with the saliva or ion-exchange with the tooth [56]. 

The main application of composite resins in contemporary dentistry is as direct repair materials in a variety of cavities teeth [117] and it is estimated that 95% of all anterior restorations and 50% of all posterior restorations are now made with composite resin [118], In addition, they are also being increasingly used as indirect repair materials for a number of uses, including as onlays and inlays [119], and as fissure sealants. 

Polyacid-modified composite resins are aimed to be used in similar applications to conventional composites, such as Class II [44] and Class V cavities [45,46], and fissure sealants [47], They have also been used as bonding agents in orthodontics [48]. 

H.C. Gungor, N. Althay, R. Alpar, Clinical evaluation of a polyacid-modified resin composite-based fissure sealant two-year results, Oper. Dent. 29 (2004) 254—260. 

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. 

V. Yengopal, S. Mickenautsch, A.C. Bezerra, S.C. Leal, Caries-preventive effect of glass ionomer and resin-based fissure sealants on permanent teeth a meta-analysis, J. Oral Sci. 51 (2009) 373-382. 

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. 

M.C. Morales-Chavez, Z.C. Nualart-Grolhnus, Retention of a resin-based sealant and a glass ionomer used as a fissure sealant in children with special needs, J. Clin. Exp. Dent. 6(2014)e551-e555. 

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. 

K. Gorseta, D. Glavina, A. Borzabadi-Farahani, R.N. Van Duinen, I. Skrinjaric, R.G. HUl, E. Lynch, One-year clinical evaluation of a glass carbomer fissure sealant, a preliminary study, Eur. J. Prosthodont. Restor. Dent. 22 (2014) 67-71. 

Today, flowable materials are used not only for most classes of restoring teeth, but also as fissure sealants. Current products differ considerably in formulation and filler content (Beun et al., 2008). Fissure sealants contain less than 25% inorganic filler, while conventional flowable filling materials have about 50-70% filler. Consequently there are considerable differences in properties between commercially available products. Beun et al. (2008) have studied the effect of these variations on rheological properties including storage modulus, and classified the products into three groups, based on their sohd-like behavior. 

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. 

The acrylic monomers preferred in the preparation of UV curable inks and coatings or in the photoprepolymer printing plate procedure are 2-hydroxyethyl acrylate (2-HEA), 2-hydroxypropyl acrylate (2-HPA), 2-hydroxypropyl methacrylate (2-HPMA), 2-hydroxy-ethyl methacrylate (2-HEMA) and 2-ethylhexyl acrylate (2-EHA). Also, 2-HPMA is used in light-sensitive compositions for fissure sealant adhesives or bonding preparations in dentistry and in Napp printing plates. Various mono(meth)acrylates can be used in water-based acrylic latex paints. Plastics dispersions of acrylic polymers are used as binders or thickeners in paints as well as in cosmetic creams. The monomer content is usually less than 0.3% (Bjorkner 1995). 

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]. 

Meyer-Lueckel, H., Paris, S., Mueller, J., Colfen, H., Kielbassa, A.M. Influence of the application time on the penetration of different dental adhesives and a fissure sealant into artificial subsurface lesions in bovine enamel. Dent. Mater. 22, 22-28 (2006)... 

For some time, the material of choice was considered to be an unfilled resin, essentially a low viscosity blend of the type of monomers used in conventional composite resins. Such fissure sealants have good retention, which is obviously highly desirable. 

---