Esthetic Alternatives for Treating Children
Is there still a place for resin-modified glass-ionomer cement restorations?
Kevin J. Donly, DDS, MS | Shahad Abudawood, BDS, MS
The current restorative armamentarium for both pediatric patients and the primary dentition includes amalgam, resin-based composite, resin-modified glass-ionomer cement, resin-faced stainless steel crowns, zirconia crowns, and stainless steel crowns. In this era of esthetics, restorative dentistry has moved toward the more esthetic restorative materials whenever possible. The introduction of nano-filled resin-based composites, high-strength and esthetic zirconia crowns, and resin-faced stainless steel crowns has changed the traditional restorative options for the primary dentition. The advent of these restorative materials has offered strength, excellent color appearance, high polish characteristics, and high bond strength of resin-based composite. When teeth are badly broken down due to the extent of caries, high-strength and esthetically pleasing zirconia crowns are available, as well as resin-faced crowns, where the amount of the tooth structure available for restoration retention is minimal or when tooth isolation is not possible.
With the introduction of these esthetic restorative materials, is there still a need for resin-modified glass-ionomer cement? The answer is definitely yes. Resin-based composites cannot be placed unless there is perfect tooth isolation to prevent saliva or hemorrhage contamination. Glass-ionomer cements can set in the presence of water; the acid-base curing reaction of glass-ionomer cement actually releases water as a by-product.1 Traditional glass-ionomer cements did not demonstrate an ideal clinical performance,2,3 but the introduction of resin-modified glass-ionomer cements have shown very good clinical performance.4,5 More current resin-modified glass-ionomer cements have greater strength and color stability.
The practitioner needs to understand that resin-based composite can only be placed in ideal situations, when tooth isolation is perfect. Resin-modified glass-ionomer cements offer an alternative when perfect tooth isolation is not possible. Not only is the restorative material forgiving and esthetic, but research has indicated that glass-ionomer cement restorations prevent secondary caries at restoration margins.6 Therefore, there is a need for resin-modified glass-ionomer cement restorations, particularly when tooth isolation is not possible. The following resin-modified glass-ionomer cement restorations remain appropriate in the primary dentition, as noted in the paper titled, “Glass Ionomer Restorative Cement Systems: An Update,” which was published subsequent to the American Academy of Pediatric Dentistry Symposium on An Update in Pediatric Restorative Dentistry.7
Class I Restorations
Resin-modified glass-ionomer cement is an acceptable restorative material for Class I restorations in the primary dentition (Figure 1 through Figure 3).4,5,7 The wear and strength of the restorative material has demonstrated positive clinical results. If the carious lesion is only in pits or fissures, the preparation should involve the removal of minimal tooth structure, as there is no concern for bulk strength in these non-stress bearing areas. Larger carious lesions require larger preparations, which include stress-bearing areas of the occlusal surface. The preparation design should be similar to that of a Class I amalgam preparation. In these situations, the bulk of the resin-modified glass-ionomer restorative material will be less susceptible to fracture. The clinician is reminded that the occlusal preparation should have non-beveled margins due to the concern that the compressive strength cannot withstand the occlusal loading forces developed at restoration margins during mastication.
Class II Restorations
Resin-modified glass-ionomer cement has also been effective as a restorative material for Class II restorations in the primary dentition (Figure 4 through Figure 6). In fact, resin-modified glass-ionomer cement Class II restorations were shown to clinically perform as well as Class II amalgam restorations in the primary dentition over a 3-year time period.8,9 Not only do these restorations perform effectively, but they have the capability to release fluoride, calcium, and phosphate ions. Glass-ionomer cements have demonstrated their ability to inhibit tooth demineralization at restoration margins and on adjacent proximal tooth surfaces.6,10 The preparation design for a Class II resin-modified glass-ionomer cement restoration is similar to a Class II amalgam preparation. Ideally, the occlusal depth of the preparation is 1.5mm, unless the extent of caries requires further dentin removal. The buccal and lingual walls of the preparation should be slightly convergent toward the occlusal surface, which follows the principle of remaining parallel to the external tooth dimensions and also aids in restoration retention. The proximal box is approximately 1.25mm axially. Again, no bevels are placed on the preparation margin due to the compressive strength of the resin-modified glass-ionomer cement and the potential for fracture at the beveled cavosurface margin.
Class III Restorations
Class III resin-modified glass-ionomer cement restorations were recommended through the AAPD Pediatric Restorative Dentistry Consensus Conference and reaffirmed during the AAPD Symposium on An Update in Pediatric Restorative Dentistry.4,5,7 Class III restorations are in a non-stress–bearing area and can perform very well clinically. The Class III preparation design is similar to a resin-based composite Class III preparation design, excluding the bevel. Again, the clinician should remember that preparation margins are not beveled when placing glass-ionomer cement or resin-modified glass-ionomer cement restorations.
Class V Restorations
Resin-modified glass-ionomer cement has also been recommended for Class V restorations.4,5,7 The newer resin-modified glass-ionomer cements have improved color stability and polishing characteristics. The Class V preparation design is similar to an amalgam Class V preparation; however, it should be extended to include all carious tooth structure. Frequently, Class V preparations leave little or no enamel at the gingival margin. Resin-modified glass-ionomer cement can be an excellent restorative choice in these instances, with the material inhibiting marginal secondary caries.
Resin-Modified Glass-Ionomer Cement as a Base
Resin-modified glass-ionomer cement is an excellent material to be used as a base below resin-based composite restorations. The glass-ionomer material has physical properties similar to dentin. Resin-based composite exhibits hydroscopic expansion that is much higher than resin-modified glass-ionomer cement. Therefore, a resin-modified glass-ionomer base reduces the amount of resin-based composite restorative material necessary in the preparation and reduces the amount of hydroscopic expansion in the final restoration. Resin-based composite can chemically bond to resin-modified glass ionomer cement, making the total restoration a singular entity. Amalgam restorative dental material has a high coefficient of thermal conductivity. A resin-modified glass ionomer cement base can protect underlying dentin and provide fluoride release to inhibit recurrent caries at restoration margins.11-14
Resin-Modified Glass-Ionomer Cement as a Cementing Agent
Resin-modified glass-ionomer cement is an excellent cementing agent for use in the practice of pediatric dentistry. The resin-modified glass-ionomer cement can be used to cement stainless steel crowns and orthodontic bands, and some manufacturers recommend it for the cementation of zirconia crowns. Its ability to create a strong physicochemical bond to tooth structure and act as a base as well as a cement make it a favorable cementing agent for crowns.
Resin-Modified Glass- Ionomer Cement for Intermediate Restorations
The use of resin-modified glass-ionomer cement is an excellent restorative option for intermediate restorations. Carious lesions in precooperative children are a great concern, particularly when financial restrictions prohibit the provision of treatment utilizing general anesthesia. Following the removal of gross caries using a round bur or spoon excavator, a resin-modified glass-ionomer cement restoration may be placed temporarily. The bonding properties and fluoride release of the resin-modified glass-ionomer cement may keep the temporary restoration intact until the patient matures and can cooperate for more comprehensive restorative dentistry.
Resin-modified glass-ionomer cement may be utilized both in the primary and permanent dentition for intermediate restorations to stabilize caries activity. Traditionally, a reinforced zinc oxide-eugenol material (IRM, Caulk/Dentsply) was recommended for these situations. Presently, resin-modified glass-ionomer cement can provide a temporary restorative material with greater strength than IRM along with the capability to physicochemically bond to tooth structure and release fluoride to inhibit adjacent tooth demineralization.
In addition, resin-modified glass-ionomer cement can be used in the treatment of teeth exhibiting enamel hypoplasia. Oftentimes, caries progress rapidly, secondarily to the hypoplastic enamel. Because it is difficult to bond resin-based composite to hypoplastic enamel, resin-modified glass-ionomer cement can provide a temporary restoration in these cases until a final permanent restoration can be placed or further breakdown of the tooth warrants full coverage.
Resin-Modified Glass-Ionomer Cement as a Sealant
Finally, there are currently resin-modified glass-ionomer cements available for sealing the occlusal surface of primary and permanent molars. These “glass-ionomer sealants” can be used for teeth that are too difficult to isolate for the placement of a resin-based sealant. As these “glass-ionomer sealants” may break away, they can be replaced with a resin-based sealant once the tooth has fully erupted and can be isolated adequately. Further research is needed to determine the long-term effectiveness of these glass-ionomer sealants.
Conclusion
Resin-modified glass-ionomer cement restorations have provided effective clinical alternatives to more traditional amalgam and resin-based composite restorations. They can be successfully used in the primary dentition for the restorations described in this article. Resin-modified glass-ionomer cement can be used in ideal clinical situations, but also in non-ideal clinical situations when tooth isolation is difficult.
References
1. Nicholson JW, Croll TP. Glass ionomers in restorative dentistry. Quintessence Int. 1997;28(11):705-714.
2. Qvist V, Laurberg L, Poulsen A, Teglers PT. Eight-year study on conventional glass ionomer and amalgam restorations in primary teeth. Acta Odontol Scand. 2004; 62(1):37-45.
3. Mjor IA, Dahl JE, Moorhead JE. Placement and replacement of restorations in primary teeth. Acta Odontol Scand. 2002;60(1):25-28.
4. Croll TP, Nicholson JW. Glass ionomer cements in pediatric dentistry: review of the literature. Pediatr Dent. 2002;24(5):423-429.
5. Berg JH. Glass ionomer cements. Pediatr Dent. 2002; 24(5):430-438.
6. Raggio DP, Tedesco TK, Calvo AF, Braga MM. Do glass ionomer cements prevent caries lesions in margins of restorations in primary teeth? A systematic review and meta-analysis. J Am Dent Assoc. 2016;147(3):177-185.
7. Berg JH, Croll TP. Glass ionomer restorative cement systems: an update. Pediatr Dent. 2015;37(2):116-124.
8. Donly KJ, Segura A, Kanellis M, Erickson RL. Clinical performance and caries inhibition of resin-modified glass ionomer cement and amalgam restorations. J Am Dent Assoc. 1999;130(10):1459-1466.
9. Croll TP, Bar Zion Y, Segura A, Donly KJ. Clinical performance of resin-modified glass ionomer cement restorations in primary teeth. A retrospective evaluation. J Am Dent Assoc. 2001;132(8):1110-1116.
10. Donly KJ, Segura A, Wefel JS, Hogan MM. Evaluating the effects of fluoride-releasing dental materials on adjacent interproximal caries. J Am Dent Assoc. 1999;130(6):817-825.
11. Griffin F, Donly KJ, Erickson R. Caries inhibition of three fluoride-releasing liners. Am J Dent. 1992;5(1): 293-295.
12. Rabchinsky J, Donly KJ. A comparison of glass ionomer and calcium hydroxide liners in amalgam restorations. Int J Periodont Restor Dent. 1993;13(4):378-383.
13. Donly KJ, Souto M. Caries inhibition of glass ionomer. Am J Dent. 1994;7(2):122-124.
14. Donly KJ, Ingram C. An in vitro caries inhibition of photopolymerized glass ionomer liners. ASDC J Dent Child. 1997;64(2):128-130.
About the Authors
Kevin J. Donly, DDS, MS
Professor and Chair
Department of Developmental Dentistry
School of Dentistry
University of Texas Health Science Center at San Antonio
San Antonio, Texas
Shahad Abudawood, BDS, MS
Clinical Assistant Professor
Department of Developmental Dentistry
School of Dentistry
University of Texas Health Science Center at San Antonio
San Antonio, Texas
