The Evolution of Glass Ionomer Restorative Materials - Oral Health Group (2023)

Glass ionomers have experienced many innovations in dentistry. They were the first materials developed to resist repeated deterioration. They were the first bioactive materials to release fluoride in an acidic environment and replace or replenish lost fluoride ions when returned to the oral environment. They were the first easy-to-use bulk fill material. Many improvements have been made to the original formulas, now featuring better handling, strength, wear rate and aesthetics. In addition, there are many new applications for glass ionomers as they approach their 50th anniversary.

History of Glass Ionomers
Dr Alan Wilson and Dr. Brian Kent of the British Laboratory of the Government Chemist, who experimented with mixing silica glass with polyacrylic acid, first synthesized glass ionomers in 1965. They determined that the curing mechanism was an acid/base reaction. In 1975, the first commercially available glass ionomer was produced. Dr John McLean was the first to develop clinical techniques and demonstrate the material's resistance to caries. Over the years, improvements have been made to the original formulations to speed up setup and allow for instant shaping. A small loyal group of dentists used the materials successfully, but their growth was overshadowed by the development of better dentin bonding agents and composite resins.

In the past 10 years, interest in glass ionomer materials has increased again. Many companies have added glass ionomers to their restorative product lines. As the use of direct metal restorative materials has declined, dentists have looked for ways to use tooth-colored materials in all procedures. Composite resins have limitations and alternative materials were needed to complete the transition. Glass ionomers are the perfect complement to other esthetic restorative materials and allow dentists who wish to eliminate direct metal restorations from their practice to successfully do so.

Advantages of glass ionomers
Direct glass-ionomer restorations are easier to putty and have less postoperative operator sensitivity than composite restorations.1,2 The hardened material has a coefficient of thermal expansion similar to that of the tooth structure.3 Glass ionomers are antibacterial.4 They are not as sensitive to moisture fluctuations in the restoration area during seating as composites and have a stable, long-term bond to dentin that generally does not deteriorate over time.5 Resin adhesion to dentin has been shown to gradually decrease over time due to MMPs, hydrolysis, polymerization shrinkage and other factors.6,7,8 The greatest advantage of glass ionomers is their ability to release fluoride during an acid attack and to absorb fluoride ions when present in the oral environment.9

Placement of Class V glass ionomer restoration
Glass ionomer restoratives were originally indicated for the repair of Class V dentine lesions. Tooth decay around areas of gingival recession can be problematic for older people who suffer from xerostomia because of all the medications they are taking. It has been reported that medications are the most common cause of decreased salivary function and that 80% of the most commonly prescribed medications cause xerostomia.10

An elderly patient presented with a Class V lesion around the maxillary cervical first premolar. The canine was extracted due to caries, implanted and covered until complete bone integration. It was decided that a glass ionomer restoration would be ideal for this high caries risk patient with cervical caries who will have an implant restoration. Implants often have open gum areas due to papilla loss, where food and plaque more easily build up, making them more susceptible to recurrent tooth decay.

The patient was anesthetized and a retractor wire (Dux Dental Gingibraid 1E) was placed to retract and protect the gingival tissue during preparation.(Abd. 1). A 330 burr on a high-speed handpiece with copious amounts of water spray was used to initially shape and outline the prep. A #2 round auger was used on a low speed handpiece to finish the dig and ensure all rot was removed. The finished restoration was carefully washed and evaluated(ab. 2).

(Video) Operative Dentistry | Composite Resin & Glass Ionomer | INBDE, NBDE Part II

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The restoration was treated with polyacrylic acid (GC cavity conditioner) for 10 seconds and washed thoroughly and lightly blown with air to leave a damp but not wet surface.(Abd. 3). Treatment with this conditioner improves the strength of the bond between the restoration and the tooth. A pre-encapsulated glass ionomer (GC Fuji IX GP Extra) was selected. It was first tapped on the counter several times to loosen the powder. It was then placed in the dispenser and squeezed once to ensure the plunger was fully inserted and activated. The capsule was crushed for 10 seconds. Pre-encapsulated glass ionomers deliver predictable results, are easier to use and provide consistent setting times.

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The mixed glass ionomer was placed in an applicator and applied to the restoration (GC Capsule Applier III). A composite placement tool was used to push the material out to ensure the edges were sealed. The area was isolated, kept dry, and allowed to cure for two and a half minutes.(Abb. 4, 5). A very fine diamond bur with copious amounts of water spray was used to shape the hardened glass ionomer, while a worn and scratched composite placement tool was used to keep the gingiva out of the way (Premier 201.3VF).(Abd. 6). The cord was removed and the restoration and tooth were veneered together.

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(Video) Glass ionomer cement simplified!

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The formed restoration was washed and completely dried and a surface sealant was applied with a brush over the entire unetched restoration (GC G Coat Plus).(Abd. 7). Acid should not be applied to hardened material before a surface sealer has been added. The area was light cured for 20 seconds(Abd. 8). The finished restoration was evaluated and shown to the patient.(Abd. 9).

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Class II glass ionomer restoration
A patient came to our office for the replacement of a leaky and defective amalgam filling. The patient was anesthetized and the old restoration was removed. Decomposition was unearthed and was visible near the pulp. Decadence undermined many humps(Abd. 10). Postoperative sensitivity and polymerization shrinkage stress were concerns, therefore, glass ionomer was chosen as the restorative material. There were concerns about pulpitis and maybe later a broken hump. The tooth will likely need a crown later on.

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Mesial and distal sectional matrices were placed (Triodent V-3 sectional matrix system)(Abd. 11). The desired contact surfaces were polished against neighboring teeth. The tooth was treated with a glass ionomer dentin conditioner (GC Fuji IX GP Extra) for 10 seconds and washed thoroughly. Air was lightly blown onto the dentin to remove accumulated water, but the dentin was left moist. An encapsulated glass ionomer was mixed and placed on the tooth (EQUIA-GC America). A gloved thumb was pressed against the material for two and a half minutes to ensure there were no gaps. The dies and retainers have been removed. A very fine football diamond (Premier Diamond 285.5VF) with copious amounts of water spray was used to shape the occlusal surface and a very fine diamond tipped bur was used to shape the interproximal areas. The occlusion was adjusted and the contacts checked with dental floss. Metal bands were placed back in the interproximal areas. The restoration was carefully washed and dried; an applied and light cured surface seal (GC EQUIA Coat Plus)(Abd. 12). Several hundred similar restorations have been used in my practice over the last 10 years and they have been successful.

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New improved high strength glass ionomer posterior restorative materials
New newly introduced high viscosity glass ionomer materials designed for downstream use (GC EQUIA Forte)(Abd. 13). Strength has been increased and wear rates reduced. The most common reason for composite resin failure is recurrent caries. Although glass ionomers are not as strong as composite resins, in many cases their overall durability can be superior to that of composite restorations. People with high caries rates will have little success with composite resin restorations. Glass ionomer fillings may last longer than composite fillings in young people who consume large amounts of sugar, drug addicts, patients with xerostomia, elderly people with recession, and patients with poor oral hygiene. The advantages of glass ionomers generally outweigh their disadvantages.

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Multiple Class II glass ionomer restorations
A patient who has been attending the clinic for 30 years reported regular examinations and prophylaxis. Interproximal digital radiographs were taken and found abnormally high areas of new interproximal caries (Dexis-Platinum)(Abd. 14). Although she was examined regularly, no surgical treatment had been performed for over eight years. There was a big change in her medication.

Initial excavations were initiated on the first molar and second premolar to determine the extent of caries.(Abd. 15). The first premolar and canine were prepared and the first molar restored with a high strength glass ionomer restoration (GC-EQUIA Forte).(Ab. 16). It was determined that a 50-year-old patient who had had no fillings for years and then required 16 fillings was in need of a bioactive material that releases fluoride. Sectional matrices were used (Triodent V-3 sectional matrix system) and all posterior teeth were restored with high-strength glass ionomer. The canine was restored with composite resin. The restorations were shaped and sealed(Abd. 17). The remaining areas in the mouth were similarly restored in subsequent appointments.


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Glass ionomer direct restorative materials, along with composite resin materials, allow dentists to restore metal-free teeth. The ability of the glass ionomer to resist repetitive degradation, the biggest cause of direct composite failure, is very important. When looking at the big picture, a material's strength is not always the best indicator of its longevity. Due to ease of use, excellent retention, reduced post-operative sensitivity and anti-cariogenic properties, the use of glass ionomers is expected to continue to increase. Glass ionomers should be part of every dentist's restorative kit.OH

Oral Health appreciates this original article.

1.Opdam NJ, Feilzer AJ, Roeters JJ, Smale I. Class I composite occlusal restorations: postoperative in vivo sensitivity, wall adaptation and microleakage. Bin J Dent. 1998;11(5):229-234.
2. Akpata ES, Sadiq W. Postoperative sensitivity in glass ionomer versus later bonding resin line composites. Bin J Dent. 2001;14:34-38.
3.Browning W. D. The benefits of self-adherent glass-ionomer materials in restorative dentistry. Compend Contin Educ Dent. 2006;27::308-314.
4. Menon T, Kumar CP, Dinesh K. Antibacterial activity of glass-ionomer restorative cements and polyacid-modified composite resin against cariogenic bacteria. Indian J Med Microbiol. 2006;24:150-151.
5. Albers H.A. Tooth Color Restorative Materials: Principles and Techniques 9th ed. Hamilton, Ontario: BC Decker Inc. 2002:43-55.
6.Pashley DH, Tay FR, Yiu C, Hashimoto M, Breschi L, Carvalho RM, Ito S. Collagen degradation by host-derived enzymes during aging. J Dent Res. 2004;83:216-221.
7. Hashimoto M, Ohno H, Sano H, et al. Micromorphological changes in resin-dentin bonds after 1 year of storage in water. J Biomed Mater Res. 2002;63(3):306-311.
8.Giachetti L, Russo DS, Bambi C, Nieri M, Bertini F. Influence of operator skill on microleakage of total etch and self-etch adhesive systems. J Dent. 2008;36(1):49-53.
9. Dejan Lj Markovic, Bojan B Petrovic and Tamara O Peric. Fluoride content and rechargeability of five glass-ionomer dental materials. BMC oral health. 2008;8-21.
10.Gupta A, Epstein JB, Sroussi H. Hyposalivation in elderly patients. Association J Can Dent 2006; 72(9):841-6.

(Video) Glass Ionomer Restorative Material | Ketac molar | GIC | ART | Dental Maestro | Dr.Jyoti Agarwal

Regarding theAuthor
Dr Ward has a private practice in Columbus, Ohio. He is a Diplomate of the American Board of Aesthetic Dentistry, a Fellow of the American Society for Dental Aesthetics, and a Fellow of the International College of Dentists. He is a reviewer for the Journal of Prosthetic Dentistry and the Journal of Esthetic and Restorative Dentistry. He has lectured internationally and written seminal articles in the area of ​​proportionate smile design.

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