January 3, 2019
by Carla Cohn, DMD
In today’s fast paced world where information is available with only a few keystrokes, we must be ready to embrace new ideas, adapt and learn. As dental professionals, we live in an ever-changing discipline of new materials and techniques. Even after we have completed our formal educations, our lives continue in a constant state of learning and continuing education. I graduated dental school nearly three decades ago, and I can honestly say that the majority of my mainstream daily dental treatment today makes use of materials that either did not exist during my dental school days, or at the very least were only beginning to emerge. It is safe to say that in another ten, twenty or thirty years, dentistry will look very different again. But, as we are creatures of habit, and become comfortable in our routines, it can be difficult to accept and adopt new concepts. One thing that is certain though, we must be willing and able to adapt, or, we will become extinct like the dinosaurs. Step out of the comfort zone of the familiar and let us explore what is new and improved in paediatric restorative materials.
As a general dentist, my clinical practice is limited to a specific group of patients, the paediatric patients. Thus, my emphasis will be on those materials specific to use for children. I have the good fortune and wonderful opportunity to be on the cutting edge as innovations in dentistry appear. In this article, I will review: glass ionomers, bioactive composite materials, bulk fill composite materials, aesthetic zirconia full coverage options, resin infiltration, and silver diamine fluoride. Each category of material has inherent clinical indications, as well as strengths and weaknesses. With so many options in our armamentarium, it is important to become well versed in our materials and be able to take advantage of what is available. Some of the materials you may be familiar with, others less so. Whether you incorporate these options into your practice currently, are planning to do so, or not, it is critical that we are well educated. In a world that is so savvy with available choices, patients’ parents are searching and demanding those options. As awareness continues to grow, so too does our responsibility.
Bioactive restorative materials have flooded our dental world. Perhaps the earliest category of bioactive materials are glass ionomers: Equia (GCA), Riva SC (SDI), Ionostar molar (VOCO), FX-II (Shofu), Chemfil (Dentsply Sirona) and resin modified glass ionomers: Fuji II LC (GCA), Riva LC (SDI), Ionolux (VOCO). Glass ionomers are a combination of fluoro-alumina silicate glass and the ionomer, polyalkenoic acid, which when mixed together form the material glass ionomer cement or glass ionomer cement restorative. Resin modified glass ionomers share this same chemistry, but with the addition of resin, which reinforces the material and adds a dimension of aesthetics to the material. Glass ionomers have been used for many years as cements and restoratives, but recently they have undergone significant improvements. In the past challenges with strengths and aesthetics of glass ionomer materials were common. While they still do not approach the physical strength and durability of other restorative materials, for example composite resins or full coverage crowns, they have vastly improved. Today’s glass ionomers not only release significant amounts of fluoride, and are rechargeable, but they have reached a new level of longevity and aesthetics. Used widely in Europe and Asia as definitive restorative materials for deciduous teeth, they are only recently gaining more and more acceptance in North America. Favourable properties of glass ionomers and resin modified glass ionomers include: chemical bonding to both enamel and dentin, thermal expansion similar to that of tooth structure, biocompatibility, uptake and release of fluoride, and decreased moisture sensitivity when compared to composite resins. Because of these excellent properties, glass ionomers and resin modified glass ionomers are the material of choice in a behaviourally challenged or special health care needs child in which we have difficulty maintaining a dry field, or must work very quickly. Clinical indications for glass ionomer are: atraumatic or interim restorative techniques in pre-cooperative or un-cooperative patients, or base material for sandwich techniques. With increased aesthetics and strength, the indications for resin modified glass ionomers are: non-stress bearing class I or II, class V restorations for deciduous teeth and sandwich co-curing technique. Several studies confirm the success of glass ionomers and resin modified glass ionomers when compared to other restorative materials. As improvements in chemistry of glass ionomers and resin modified glass ionomers have been made and are likely to continue they will surely become more standard as a definitive restorative material for our child patients (Figs. 1 & 2).
Composite resins are the most common restorative material used in North America. They too have evolved into formulas which are bulk fill and bioactive materials, and sometimes the two properties combined. Bulk fill composites have been available for a short time only. Several on the market are excellent: SDR Flow Plus (Dentsply Sirona), Estelite Bulk Fill (Tokuyama), x-Tra base (VOCO), Beautifil Bulk (Shofu), Ecosite (DMG) , Reveal (Bisco). Bulk fill composites allow for a faster fill technique than incremental technique which is a valuable time saver, especially relevant when working with children who have a limited ability to sit still and tolerate dental treatment. These bulk fills all share in common a greater translucency which simply allows the light to penetrate and cure to greater depths. Figure 3. Bioactive composites have emerged as well. Beautifil (Shofu) are a combination of resin and glass ionomer which contain surface pre-reacted glass (PRG) as a filler in the resin. The surface pre-reacted glass confers multiple properties to the resin including the cariostatic qualities, fluoride recharge ability, anti-plaque effect, acid neutralization, and allows acceleration of calcification. Giomers are able to recharge from external fluoride sources. Giomer restorations resist plaque formation due to a film that forms on the restorative surface when it contacts saliva. This film consists of aluminum, silica, strontium and other ions that originate from the giomer fillers and act to inhibit bacterial adhesion. Remineralization occurs at surfaces adjacent to giomers. Figures 4 and 5. Another innovative restorative material is an ionic resin modified glass ionomer, Activa Kids (Pulpdent). Unique properties of this materials are release of fluoride, calcium and phosphate, again with the ability to recharge. Activa works with saliva to exchange the ions fluoride, calcium and phosphate, it contains rubberized resin component to guard against fracture and contains no BPA BisGMA or Bisphenol A (Figs. 6 & 7). Work published by Nedeljkovic et al in the Journal of Dental Research in 2016 studied biofilm developed on different restorative materials. The findings are that the lack of buffering by traditional composites promotes a shift to more cariogenic bacteria and that buffering of restorative material does have an impact on the microbial composition of the biofilm. These bioactive composite type materials clinical indications are the same as our traditional composites. Strength and durability are reliable, and aesthetics are superb. I describe these bioactive materials to “composites on steroids” as they have all of the advantages of our traditional composites in addition to favourable properties that can only benefit our restorations for our children.
Stainless steel crowns are alive and well, however we have finally reached the time when we can restore children teeth with aesthetic crowns and restore white smiles. Aesthetic prefabricated full coverage materials in the form of prefabricated zirconia crowns are available for both posterior and anterior applications by NuSmile (Figs. 8 & 9), Sprig, KinderKrown, and Cheng. These crowns are monolithic yttrium stabilized zirconium, offer full cover protection and unsurpassed aesthetics. Paediatric zirconia crowns have brought a new era of full coverage to our paediatric patients. Years of stainless steel crowns and full metal smiles can be left in the past. We now have the ability to aesthetically restore both form and function to our children.
Resin infiltration, Icon (DMG) is the replacement of lost tooth structure with an infiltration of fluid resin. It does not require anesthesia or removal of tooth structure, besides acid etching. Resin infiltration effectively arrests the demineralization process. Three steps are involved: a HCl etchant which erodes the surface of the lesion and exposes the lesion’s porosities, a drying step of ethanol, and finally, infiltration with an unfilled low viscosity light cured resin material. It is a micro-invasive treatment method that creates a diffusion barrier not only on the surface, but within the hard tissue thus stabilizing and arresting the caries progression. Resin infiltration can be used to restore interproximal lesions that are less than or equal to a penetration of the outer third of dentin. Additionally resin infiltration can be used to mask white spot lesions on smooth surface, for example post orthodontic demineralization lesions areas of hypocalcification etc,. (Figs. 10 & 11). A Cochrane review of 2015, concluded that available evidence shows that micro-invasive treatment of proximal caries lesions arrests non-cavitated enamel and initial dentinal lesions (limited to outer third of dentine, based on radiograph) and is significantly more effective than non-invasive professional treatment (e.g. fluoride varnish) or advice (e.g. to floss). Resin infiltration is a technique sensitive procedure that demands a dry field for the hydrophobic material. It is a phenomenal tool.
Finally, what is old is new again. Silver nitrate is not a new concept. It has been famously discussed by GV Black in “A Work on Operative Dentistry” a century ago. It has been “re-invented” as Silver Diamine Fluoride (SDF) Advantage Arrest (Oral Science in Canada and Elevate in USA) and Riva Star (SDI). SDF is a topical agent that arrests dental caries. It is supplied as a colourless or blue liquid. It is simple to apply as a drop, with no local anesthetic and no drilling required. Silver Diamine Fluoride is most effective at a 38% concentration, which is composed of 25% silver, 8% ammonia and 5% fluoride. The silver acts as an antimicrobial, the ammonia as a solvent and the fluoride as a mineralization agent. In summary, its mechanism of action is as a bactericidal that can penetrate very well, occlude dentinal tubules and mineralize. It is a very inexpensive micro-invasive tool to manage and arrest caries. Indications for use, as per AAPD 2018 are: high caries-risk patients with anterior or posterior active cavitated lesions, cavitated caries lesions in individuals presenting with behavioural or medical management challenges, patients with multiple cavitated caries lesions that may not all be treated in one visit, difficult to treat cavitated dental caries lesions, patients without access to or with difficulty accessing dental care and active cavitated caries lesions with no clinical signs of pulp involvement. The adverse effect of SDF is that arrested caries appears black after treatment (Fig. 12). The black staining has been addressed by Riva Star (SDI). A two-step procedure has been developed in which silver diamine fluoride is placed first, followed immediately by an application of potassium iodide, which masks much of the black staining. Recommended periodicity for application of SDF is biannually at the concentration of 38%. The ability to use SDF to help children who are unable to sit for traditional treatment, or for those with poor access to care is very exciting. Use of SDF helps to arrest caries, however does not restore the tooth to form. In other words, the cavitation is not restored. In order to do this SDF application must be combined with a suitable restorative material. A method combining both silver diamine fluoride and glass ionomers is termed the “Smart” Technique”. Smart is an acronym which stands for silver modified atraumatic restorative technique. Very simply, it is the application of silver diamine fluoride, which as described, arrests caries but does not restore the tooth form combined with the application of glass ionomer to restore the cavitation (Figs. 13 & 14). These materials used together with this method allow for a non-invasive atraumatic restoration to be used to help our uncooperative, unwilling or unable patients.
In summary, we have at our disposal a new and improved armamentarium of dental restorative materials for our paediatric patients. All, without exception, provide improvements over past materials to us and our patients. I am often asked what single specific material I recommend and ultimately the answer comes down to the patient. The choice of material depends upon three factors: the clinical diagnosis and the goal of treatment for our child, the child’s ability to complete treatment, and the ability of the practitioner to complete treatment for that child. We are presented with much compelling science and evidence of the superiority of any given material over another and each of us have preferences in the handling of said materials. Not all practitioners are created equally, nor are all patients, and certainly the practitioner’s ability is dependent upon the child’s ability. Ultimately when working with children, the goal of the treatment must be determined based upon the child. Is the goal to restore form and function? Are we to re-create both health and aesthetics. Or is the goal to simply buy some time? Whatever the case may be, there are choices available to us as practitioners. Our duty is to our patients whom we serve to provide the best. Always remember, kids’ teeth matter! OH
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About the Author
Dr. Cohn is a general dentist, devoted solely to the practice of dentistry for children. She maintains a private practice at Kids Dental in Winnipeg, Canada. She is proud to be a member of the American Academy of Pediatric Dentistry Speakers Bureau, Catapult Education Speakers Bureau, Pierre Fauchard Academy, and a cofounder of Women’s Dental Network. Dr. Cohn has been named as Dentistry Today’s Leader in Continuing Education multiple years in a row. She has published several articles and webinars, and enjoys lecturing on all aspects of children’s dentistry for the general practitioner both nationally and internationally.