Dby Dr. Sam Simos

Dr. Sam Simos is recognized as a leader

in cosmetic and restorative dentistry.

He earned his DDS from Chicago’s Loyola

University.

Simos teaches postgraduate courses

to practicing dentists on cosmetic dentistry, occlusion and comprehensive restorative dentistry

through Allstar Smiles’ learning center and client facility in Bolingbrook, Illinois, and throughout the

country. He is committed to promoting awareness, communication and education within the dental

profession through lecturing around the country and being the author of internationally published

professional articles on the use of innovative techniques and materials.

When the conditions are right, consider resin-modifi ed glass ionomers for direct or indirect restorations

Material

GoodsDespite ongoing advancements of dental restorative products,

no single material on the market can address all clinical scenarios. The past few decades might suggest that composite resins have a competitive edge over other material classes, but resin-modifiedglass ionomers (RMGIs) must not be overlooked as viable options when performing direct or indirect restorations.

It can be argued that RMGIs should have a place in every clinician’s offi ce, regardless of how far composite resins have come. RMGIs possess numerous qualities that are still elusive to composite resins, including elasticity, high natural bond strength to the tooth and, most impressively, active fl uoride release. Indeed, some clinical situations will arise that require the use of RMGIs. This article will acquaint readers with today’s RMGIs and showcase some of their benefi ts.

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The previous generation: glass ionomers

To fully comprehend RMGIs, one must fi rst under-stand the basics of their glass ionomer predecessors. Glass ionomers (GIs) are composed of a basic glass (fl uoroaluminosilicate) and a polyalkenoic acid (most commonly polyacrylic acid), which produce a self-curing material that doesn’t require light activation.1,2 They’re best known for their continuous f luoride release, biocompatibility and ability to form a true chemical bond to the dentin. These qualities are derived from the acid/base reaction that takes place between the two components.1

However, GIs exhibit a few drawbacks, including low wear resistance, moisture sensitivity and poor handling, which has caused dentists to shy away from them in practice.

RMGIs were developed in an attempt to propagate the advantages of GIs while mitigating their shortcomings. RMGIs are glass ionomers mixed with a small amount of resin (typically 4.5–6 percent).1 The added resin, along with fi ller modifi cations, is enough to yield a new class of hybrid restorative materials that retains most of the benefi ts of conventional GIs but shows signifi cant advantages, such as the ability to be light-cured, improved handling, better strength and improved aesthetics.

The new class: RMGIsRMGIs have been well established as luting cements

since their inception in the early 1990s, but only recently has their scope expanded into the area of direct restorations.3

Outside of cementation, the most highly touted applications of RMGIs are observed in pediatric and geriatric dentistry. Older and younger populations present dentists with constraints that require a reliable material with the capability for quick and proper placement, and RMGIs have proved to facilitate this need.4 Both demographics also can benefi t immensely from the fl uoride release of RMGIs because they’re at higher risk for developing secondary caries.

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A 24-year-old patient with a history of moderate/severe caries profi le, fair hygiene and a poor track record of keeping his dental appointments presented with MO decay in #18 (Figs. 1 and 2).

I decided to use Ionolux by Voco as an RMGI liner, in an open sandwich technique (Fig. 3), instead of a closed sandwich technique (Fig. 4) with Admira Fusion by Voco as the composite capping material. I opted for Ionolux because it’s manufactured with a pure form of polyacrylic acid. With the ionic exchange mechanism of adhesion which is characteristic of RMGIs, a superior bond strength to the tooth is achieved. This entirely eliminates the need for an adhesive, which can save clinicians valuable time.

(Because of Ionolux’s inclusion of a pure form of polyacrylic acid, as mentioned above, the use of a dentin conditioner is not required; nevertheless, clinicians may include this step for the sake of scrupulousness, as long as a mild conditioner is used.1)

Unlike composite resins, which are the typical selection of most clinicians, RMGIs are inherently hydrophilic, which make them good candidates for scenarios in which isolation may be problematic.

In fact, clinicians must take care not to overdesiccate the target area when using an RMGI; otherwise, they run the risk of impairing the physical properties of the material.

After preparation and isolation of the Class II restoration was accomplished with the Palodent Plus matrix system from Dentsply Sirona (Fig. 5), the RMGI was placed into the proximal box (Figs. 6 and 7) and light-cured for 20 seconds. Once cured, the tooth was conditioned with 32% Uni-Etch phosphoric acid etchant from Bisco (Fig. 8). Futurabond DC bonding agent from Voco was placed and light-cured for 20 seconds (Fig. 9).

Admira Fusion (Fig. 10) was then placed in 2-millimeter increments and contoured; the rubber dam was removed and proper occlusion was obtained. Finishing and polish was accomplished with a single-use composite polishing system from Darby Dental (Fig. 11). The resulting restoration (Fig. 12) provides a predictable and long-term solution that affords both patient and clinician peace of mind for years to come.

Case study

Fig. 1 Fig. 2

Fig. 5 Fig. 6

Fig. 8 Fig. 10Fig. 7

Fig. 12

Fig. 9

Fig. 11

Fig. 3

Composite

GIC exposed to oral cavity

GICGIC

Composite

Enamel

Fig. 4: Closed sandwich technique

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Because of their hydrophilic nature, RMGIs are also great candidates for hard-to-reach restorations. They can be used in deep restorations or buildups as liners when utilizing the sandwich technique, on account of their elasticity and biocompatible tendency to soothe the pulp. For patients on strict medicinal regimens who experience decreased saliva, RMGIs can be a smart choice because the fl uoride-releasing feature allows the material to thrive in acidic environments.

ConclusionClinicians have many choices of materials on the

market today. Regardless of the most popular or most familiar materials on the market, clinicians have a responsibility to seek out the best materials for the clinical situation that presents. RMGIs are proven restorative materials that are underutilized in most American dental offi ces today, but they should be considered more often as a strategy to help increase the longevity and predictability of direct and indirect restorations. ■

References1. Koirala, Sushil, and Yap, Adrian. “A Clinical Guide to Direct Cosmetic Resto-

rations with Giomer.” Leipzig: Dental Tribune International, 2008. Print.2. Berzins, D.W., Abey, S., Costache, M.C., Wilkie, C.A., and Roberts. H.W.

“Resin-Modifi ed Glass-Ionomer Setting Reaction Competition.” Journal of Dental Research. 89:1; 82–86.

3. Sidhu, Sharanbir K., and Nicholson, John. “A Review of Glass-Ionomer Ce-ments for Clinical Dentistry.” Journal of Functional Biomaterials 7.3 (2016).

4. Margeas, Robert C., DDS. “Simplifi ed Delivery of a Resin-Modifi ed Glass Ionomer Restorative.” Dentistry Today, March 7, 2011.

Resin-modifi ed glass ionomers possess numerous qualities that are still elusive to composite resins.

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