Innovative Materials for Glass Ionomer Cements (GICs): Dental Applications

Sandra Forbes

Product Manager

INTRODUCTION

Advancements in dental restorative materials are fueled by the quest for biocompatible solutions that mimic natural appearance. Traditional dental materials, such as amalgam and composite resins, possess inherent drawbacks. Amalgam, despite its functionality, suffers from aesthetic deficiencies and contains mercury, sparking concerns regarding potential toxicity and bodily release. On the other hand, resin-based materials enhance aesthetics over amalgam but are susceptible to technical intricacies in bonding and are labor-intensive in application.

Glass ionomer cements (GICs), also recognized as glass polyalkenoate cements, emerge as an appealing substitute for amalgam and resin composites in dental practices. These cements boast an array of advantageous characteristics that render them ideal for various dental applications. Predominantly employed for implant stabilization and reconstructive surgeries, GICs can be directly placed in cavities, eliminating the need for additional bonding agents. By adjusting their composition, GICs can be customized to cater to diverse requirements, including sealing or underlining cavity floors, luting procedures, core build-ups, high fluoride-releasing formulations, and even pediatric-specific cements.

BENEFITS OF GIC MATERIALS

Glass Ionomer Cements (GICs), renowned for their multifaceted advantages, are witnessing a surge in popularity across numerous dental applications. Their inherent benefits encompass:

• Safety

– Unparalleled biocompatibility, ensuring no inflammatory reactions or toxicity concerns.

– Free from both Bisphenol A and mercury, providing a safer alternative.

• Exceptional Physical and Chemical Properties

– Demonstrating thermal compatibility and minimal thermal expansion, ensuring stability.

– Exhibiting strong adhesion to mineralized tissues like enamel and dentin, as well as glass particles and base metals.

– Possessing a stable and durable ionomer chemical structure, ensuring longevity.

• Ease of Use

– Rapid setting time, streamlining the application process.

– Versatile physical properties that can be tailored by adjusting the powder-to-liquid ratio.

– Formulated to release fluoride, acting as an effective anti-caries agent.

• Aesthetic Appeal

– Providing a natural-looking restoration that blends seamlessly with the surrounding teeth.

EXAMPLES OF CONVENTIONAL IONOMERS

Traditional Glass Ionomer Cements (GICs) primarily consist of a blend of a polymeric ionomer, such as polyalkenoic acid, and silicate glass particles ranging in size from 15 to 50 micrometers. During the curing process, the ionomer intertwines with the glass particles, creating a robust network structure. The carboxylate groups present in the ionomer function as crucial network modifiers, facilitating cross-linking and the formation of salt bridges with metallic ions. These conventional ionomers, illustrated in Figure 1, are typically homopolymers or copolymers derived from unsaturated mono-, di-, or tricarboxylic acids, or polyphosphonic acids.

Figure 1.

The ionomer component holds paramount significance in dictating the quality and properties of Glass Ionomer Cements (GICs). Key GIC attributes, including cure time, adhesion strength, and cement durability, are intimately tied to the ionomer's composition, structural arrangement, viscosity, molecular weight, and polymer dispersity. Furthermore, the purity of the ionomer, with a keen eye on trace monomer and oligomer contents, is instrumental in shaping the ultimate properties of the GIC.

INNOVATIVE IONOMERS FOR NEXT GENERATION OF GICS

Despite their numerous benefits, conventional Glass Ionomer Cements (GICs) suffer from relatively inferior mechanical properties, resulting in low fracture strength, reduced toughness, and diminished durability. Specifically, their low tensile strength renders them inadequate for applications involving high stress areas, like Class II restorations, especially when cavity wall support is inadequate. Consequently, the employment of conventional ionomers is constrained to non-stress-bearing restorations. To overcome these limitations, innovative GIC formulations have been devised, aimed at enhancing their properties and bolstering resistance to fracture, wear, and erosion.

Enhanced GIC formulations encompass:

• Resin-Modified Glass Ionomer Cements (RMGICs): Incorporating polymerizable resins into the GIC formula enhances its mechanical and physical attributes, notably adhesiveness and translucency.

• Hybrid Ionomer Cements (Dual-Cured and Tri-Cured): Boosting strength involves adding photocurable monomers to the GIC. This hybrid material undergoes both the acid-base ionomer reaction and photo-initiated curing. The initial setting of the cement is facilitated by photochemical polymerization, safeguarding it from premature moisture exposure. Tri-cured GICs further incorporate a chemical curing agent alongside photo-initiated and acid-base reactions.

• Reinforced GICs: The integration of metal powders or fibers into GICs elevates their overall strength. The inclusion of alumina, silica, or carbon fibers notably improves flexural strength.

• Bioactive Glass Ionomers: Incorporating bioactive glass into GICs amplifies tooth bioactivity, regenerative capabilities, and restoration efficacy. This bioactive glass can also aid in remineralizing dentin.

DESIGN OF NOVEL IONOMERS

We are pioneering synthetic methodologies that grant us heightened control over the properties of ionomer copolymers. Crafting a robust synthetic route for ionomers is imperative to achieving products with predictable and reproducible characteristics. Traditional ionomer copolymer synthesis involves acrylic acid and di/tri-carboxylic acid monomers, which possess distinct intrinsic reactivity, posing challenges in regulating molecular weight, polydispersity, and composition. Our optimized synthetic process addresses these issues by employing tightly controlled reaction conditions, precise monomer feed ratios, and meticulous addition of monomers and catalysts, thereby yielding ionomers with exacting physical and molecular properties.

Moreover, we have introduced a suite of novel monomers featuring extended linkages, designed to enhance GIC performance. Existing ionomers possess carboxylic acid groups tightly tethered to the polymer backbone, which hinders their effective conversion to ion-bonded carboxylate groups during the curing process, ultimately limiting salt-bridge formation. By incorporating monomers with varied spacer lengths between the carboxylic acid groups, we aim to bolster the properties of the cement by fostering more robust salt-bridge networks.

Furthermore, we are engaged in the development of ionomers that are devoid of polyacrylic acid. It is well-established that even in trace amounts (ppm concentrations), polyacrylic acid can restrict bioactivity and hinder the formation of apatite on the surfaces of GIC materials. Consequently, our pursuit of polyacrylic acid-free alternative ionomers aims to promote enhanced apatite formation and superior overall performance.

Aladdin’s CUSTOM MANUFACTURING CAPABILITIES

Premium, innovative raw materials serve as the cornerstone for groundbreaking dental formulations. Aladdin provide an extensive range of ionomers and monomers tailored for dental research & development and commercial endeavors, complemented by our manufacturing prowess to tailor or formulate monomers according to clients' precise specifications. This streamlined approach significantly diminishes the overall cost associated with product development and manufacturing.

Aladdinsci: https://www.aladdinsci.com/