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Dental TribuneAsia Pacific Edition | 10/201512 TRENDS&APPLICATIONS Thisarticlediscussesatreatmentap- proach change in the Minimal Inter- vention model, where high viscosity glass ionomers present some advan- tages that position it as the restora- tive material of choice in the poste- riorsectionforallpatients,especially for those with high risk of caries in- cluding children, older people, peri- odontal patients and patients on medication. Black’s classification of cavities was used in dentistry for treating dental caries for much of the last century, and lesions have therefore been treated by removing the dis- eased tissue from the tooth along with a healthy portion as well. That past reality fit the techniques and material available at the time, pri- marilyamalgam. Changes in the treatment ap- proach and the development of adhesive materials led to progress in dentistry. Minimal Intervention has changed the traditional model where treatment of caries does not justinvolveamechanicalapproach, but also requires a biological ap- proach, made possible by less in- vasive techniques; therefore the biocompatibility of the materials requiresgreaterattention. Biomaterials are, by definition, any materials that take on the functions of the tissues in natural organs, capable of imitating the properties of the tissue as far as possible in its biological environ- ment. Biomaterials must meet the requirements of functional feasi- bility, biostability, biocompatibility andsterility. No restorative material can re- place enamel and dentin perfectly, and therefore preserving these must be of the utmost importance in any treatment plan. Aware of the situation, the profession has devel- oped new techniques and dental materials that adequately restore existing lesions and may prevent secondary caries from developing. Glass ionomers were introduced into this search in dentistry several yearsago,which,duetothedevelop- ment of their characteristics, gives them great advantages over other restorativematerials. Glass ionomers have undergone numerous changes with the aim of improving their clinical properties. Theadvancesinthesehighviscosity materials offer a better alternative as restorative material than amal- gamintheposteriorsection.Thead- hesion of the glass ionomer to the dental structure is less susceptible to the loss of healthy dental struc- ture, even recovering affected dentin. Therefore these restorative materials end up being safer and more indicated in minimal inter- vention dentistry. Research sug- geststhatglassionomersusedtofill extensive lesions will facilitate the remineralisation of affected (de- mineralised)dentinatthebottomof the cavity once the infected dentin has been taken away, additionally serving as protection for the pulp. Proper adhesion will help prevent microleakage by isolating residual bacteria from nutrients, reducing itsmetabolicactivity,thusstopping the progress of demineralisation, while the calcium, phosphorous and fluoride ions available in the ionomer will increase reminerali- sation. The ultimate in MI models involves greater conservation of dentaltissue,sinceweknowtheside effects of removing the tooth me- chanically. The setting reaction of the glass ionomer is an acid-base reaction betweenthepolyacrylicacidandthe glass base: the acid attacks the glass particles, causing Ca, Al and F ions to be released. The F ions are incor- porated into the matrix, and can be spread among the structure sur- roundingthetoothandinthesalvia. Fluoridetoothpastescanbeasource of this ion for the glass ionomer. Thereleaseoffluorideprovidesanti- caries qualities that are strongly in- dicated in all patients, but with spe- cialattentiontothosemostatriskto caries (children, older people, those taking medication, etc.) and in peri- odontalpatients(exposedroots). The adhesion is the result of a change in ions between the tooth structureandthecement.Thepoly- acrylic acid in the glass ionomer attacks the tooth surface, releasing calciumandphosphateionsthatre- precipitate along with the calcium, phosphate and aluminium ions re- leased from the material, forming a union between both. A degree of adhesion is also produced between the groups of carboxylic acid and thedentincollagen. The first restorative glass iono- mer aesthetically accepted was the Fuji II (GC Europe, Netherlands), whichshowedbetterphysicalprop- erties than previous materials. Since then, the basic composition of these materials has improved and we can now say that its aes- thetic condition is suitable for the posterior section or areas where aesthetic requirements are not paramount. After polishing, and with the aim of improving this characteristic, the coat or layer has been developed, which is placed on the surface of the material making it more visually appealing and pro- tecting it from water for proper maturation,increasingitsaesthetic and physical properties. The physical properties of glass ionomers are important in the context of minimal intervention techniques. Like all water-based ce- ments, they are relatively sensitive towaterandloadsfor24hoursafter their placement, until they are fully matured.Withpropercontrolofthe procedure,theyhavedemonstrated adequate duration in areas of nor- malload.Thereissufficientbibliog- raphytoensurethatglassionomers may be used as definitive material inClassI,IIandVrestorations. The latest publications have even indicated that high density glass ionomers can be used in Class II un- der stress where the isthmus is less thanhalftheintercuspaldistance. Its low sensitivity to the tech- nique(encapsulatedionomers),asit isamaterialthatisplacedallatonce, tolerates moisture when it is han- dled,anditseaseofuseinmodelling orremovalofexcessesmakesitwell suitedtotheconditionsrequiredfor day-to-dayuseindentalsurgeries. As Dr Karl-Heinz Friedl demon- strated, these are materials that are more economically efficient than traditional ones (amalgam and composite), and they ultimately end up being more economical in theworkprocess,whichmakesthem of more interest in the current cli- matewhereitisnotonlyaboutdoing itwell,butlessexpensivelytoo. Thereisstrongcontroversyonthe potential health impacts caused by the use of amalgam, which started long ago when some members of the scientific community raised doubts about its effectiveness and safety regarding the effects on ani- mals and humans of the mercury contained in amalgams that have been used for several decades in various odontological applications. Allthisrequiresrethinkingandeven moresonowthatwehavemorebio- compatible materials with a high successratewhenitcomestoresolv- ing the requirements of restoring teeth using current MI working models.Theteamatthedentalclinic itselfsuffersthegreatestriskofcon- tamination when handling it, since itcausesmercurytobereleasedinto thesurgeryenvironment. Up to now, the restorative mate- rial that is closest to nature is glass ionomer(EQUIA,GCEurope),which is a mineral. We could say that EQUIA is in itself a new restoration concept involving two materials: a nextgenerationhighviscosityglass ionomer (Equia Fil), with a translu- cencyandaesthetichithertounseen in this type of material, and a nano- filled varnish (Equia Coat) that not only buffs the material easily, but alsoprotectsitasitmatures. With this new restoration tech- nology,wehavethehugeadvantage ofbeingabletofillacavityallatonce andcarryoutveryquickrestoration, which results in an economical restoration that is at the same time aesthetic. Another added benefit typicalofionomersasexplainedbe- fore,isthatitisnotnecessarytoiso- late the area, so we will have better adhesion in fillings where it is diffi- culttogetanadequatedryarea. Conclusion Minimally invasive restorative models,combinedwiththedemand for more aesthetic, biocompatible and lower cost materials, are caus- ing current direct restorative mini- mal intervention dentistry to move away from amalgam in order to find new systems based on glass ionomers as the material of choice intheposteriorsection.Inaddition, thisnewrestorativeconceptisaper- fectalternativeforanypatientswho reject composites for financial rea- sonsorinthosesituationswherethe isolation required for a composite maynotbeattainable. Editorial note: This article was originally publishedinGACETADENTAL212,March2010 Highviscosityionomers Amalgam alternatives in the posterior section By Dr José Ignacio Zalba Elizari,Spain Dr José Ignacio Zalba Elizari is a specialist in mi- nimally invasive dentistry. He is currently work- ing as a dentist at Zalba dental clinic in Pam- plona in Spain. Zalba can be contacted at consulta@ capdental.net. 4 5 6 1 2 3 Clinical case—Fig. 1: Initial situation with dental caries.—Fig. 2: Opening of the cavity.—Fig. 3: Application of the material (Equia Fil) all at once.— Fig. 4: Modelling after 150 seconds.— Fig. 5: Application of the nano-filled varnish.—Fig. 6: Result after light curing 20 seconds. DTAP1015_12_Elizari 14.10.15 09:12 Seite 1 456 123 DTAP1015_12_Elizari 14.10.1509:12 Seite 1