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Glass Ionomer-Resin: A Maturing Concept
G ordon
J.
C
h r is t e n s e n ,
d . d . s .,
ivi. s . d . ,
ph.d .
GLASS IONDMER RESIN: A MATURING CONCEPT Q p ver the p a st several years, a successful new concept in dental m aterials has evolved. T raditional glass ionomer has been combined w ith variations of cu rren t restorative resins. The new m aterial has been received well for m ultiple uses. This hybrid h as a combination of the good and bad character istics of glass ionomer and resin, and is superior for m any uses to eith er m aterial alone. In itiated by Vitrebond (3M D ental Products) and used m ainly as a liner, th e concept has expanded into fillers, buildups and restorations. It is being observed by several companies as a potential cem enting agent. A t th is point in the evolution of glass ionomer-resin, the commercial m aterials have these characteristics: ** stronger th a n glass ionomer and w eaker th a n restorative resin; ™ less soluble th a n glass ionomer and more soluble th an resin; ■» fluoride release a t least equal to glass ionomer; easier to use th a n glass ionomer and generally more difficult to use th a n restorative resin; <*» b e tte r esthetic properties th a n glass ionomer b u t usually less acceptable esthetically th an 248
JADA, Vol. 124, July 1993
restorative resin; *■ m olecular bond-to-tooth stru ctu re a t least equal to glass ionomer. G lass ionom er-resin is a versatile m aterial w ith significant potential for dental treatm ent. W hat follows are categories of tre a tm e n t and suggested clinical use of glass ionomer-resin. L IN E R
In the short tim e since intro duction of th e glass ionomerresin Vitrebond, this product has become the m ost popular tooth preparation liner. There has been a significant decrease in th e use of calcium hydroxide as a liner. Recently, liners of any type have been criticized by some clinicians who claim th a t th ere is no need currently for th eir use under any restoration because th e current generation of “dentin” bonding agents are able to seal tooth stru ctu re and decrease tooth sensitivity. Although bonding agents seal tooth stru ctu re w hen used properly, they do not release fluoride or produce subsequent cariostatic influence on teeth. Research has shown th a t fluoride containing glass ionom er-resin liners inhibit sim ulated dental caries activity. Why? At least some m icroleak age still occurs under bonded
resin restorations placed on dentin m argins. Fluoride release from the liner appears to escape to th e outside of the tooth. U ntil fu rth e r research proves otherwise, glass ionom er-resin liners are indicated u n d er restorations having a t least some m argins on dentin. W hat is the optim um liner thickness? Light-cure of current liners is effective up to 2 m illim eters, b u t a t least 0.5 mm is probably an adequate depth for lining am algam or resin restorations th a t have some dentin m argins. F IL L E R
W hen m aking tooth p rep ara tions for crowns or fixed prostheses, void areas in the rem aining tooth stru ctu re are often p resen t w here previous restorations have been removed. Filling these holes w ith thickly mixed traditional glass ionomer or glass ionomerresin provides a nearly ideal replacem ent for m issing dentin. The m aterial bonds to under lying tooth structure, and it does not need m echanical undercuts. It is cariostatic because of fluoride release, and it h as expansion-contraction characteristics sim ilar to tooth structure. Both tradition al glass ionom er and glass ionomer-
CHRISTENSEN) resin are relatively easy to use for th is purpose. B U IL D U P
W hen a significant am ount of tooth stru ctu re is m issing during a tooth preparation for a crown or fixed prosthesis, m ost authorities now recommend building up the rem aining tooth stru ctu re to provide adequate retention for th e subsequent crown restoration. Although traditional glass ionomer is som ew hat w eak for large tooth buildups, glass ionom er-resin is adequate for a t least sm all to m oderate buildup needs. Exam ple strengths of buildup m aterials are: traditional glass ionomer, 18,000 pounds per square inch; glass ionomerresin, 25,000 psi; composite resin, 40,000 psi; and am algam , 60,000 psi. Am algam or composite resin are indicated for larger buildups, retained by pins, undercuts and/or adhesive agents. T O O T H R E S T O R A T IO N S
G lass ionom er-resins are nearly ideal restorative m aterials for patien ts having high need for cariostatic activity. Most often these are pediatric or geriatric patients. These m aterials are especially indicated for p atients for whom new dental caries can be expected unless fluoride release is present in the restor ative m aterial. D entists using glass ionom er-resin restorative m aterial have observed th a t clinical use of these m aterials for restorations is relatively easy, and th a t th e esthetic resu lt is adequate to very good. S trength lim itations and potential w ear characteristics dictate the use of these m aterials m ainly in non
occluding areas (Class 3,5), and in all prim ary tooth classifica tions having m inim al longevity expectations before exfoliation. In the past two years, there have been constant improve m ents in glass ionomer restorative m aterials, and it is expected th a t fu rth er positive changes will be made. These restorations are indicated for situations requiring m oderate strength, high cariostatic activity, m oderate esthetics and relative ease of use. C EM ENTS
Look for the introduction of glass ionom er-resin cement from several companies. The Den-M at products, Geristore and Infinity, have physical characteristics close to glass ionomer-resin, and both are used currently as cements. They do not have a true glass ionomer chemical reaction during setting, but they have been wellDr. Christensen is co-founder and accepted as currently senior easily used, consultant of highly Clinical Research Associates, Provo, retentive, non Utah, and a wellsensitivity known practitioner, researcher and producing international cem ents for speaker. He has a master's degree in situations restorative dentistry needing high and a doctorate in resistance to education and psychology. He is removal. board certified in It is prosthodontics. anticipated th a t soon to be released glass ionom er-resin cements will be significant additions for
cem entation of crowns and fixed prostheses. P R O D U C T S A V A IL A B L E
The following glass ionomerresin products are available now: Fuji II, LC (GC America Inc.); Photac-Fil (ESPE Premier); Variglass (L.D. Caulk/Dentsply); V itrem er (3M). Products sim ilar to glass ionomer-resin, G eristore and Infinity (Den-M at Corp.), have also been promoted and wellreceived for the uses described in th is article. However, m ost people do not categorize these products as glass ionomer-resin, b u t ra th e r as resins containing glass ionomer. Com parisons of these products show varying results, and more tim e is needed for adequate clinical comparisons of b rand nam es. SUMMARY
Glass ionom er-resin is now available from several com panies. The products have been well-accepted for m any uses. Expect continued im provem ents and new product introductions, b ut don’t wait. These products satisfy m any current needs in dentistry. ■ Information about the products mentioned in this article may be available from the author. N either the author nor the American Dental Association has any commercial interest in the products listed. The opinions expressed are those of the author and do not necessarily reflect those opinions or policies of the American Dental Association.
JADA, Vol. 124, July 1993
249
J.
C
h r is t e n s e n ,
d . d . s .,
ivi. s . d . ,
ph.d .
GLASS IONDMER RESIN: A MATURING CONCEPT Q p ver the p a st several years, a successful new concept in dental m aterials has evolved. T raditional glass ionomer has been combined w ith variations of cu rren t restorative resins. The new m aterial has been received well for m ultiple uses. This hybrid h as a combination of the good and bad character istics of glass ionomer and resin, and is superior for m any uses to eith er m aterial alone. In itiated by Vitrebond (3M D ental Products) and used m ainly as a liner, th e concept has expanded into fillers, buildups and restorations. It is being observed by several companies as a potential cem enting agent. A t th is point in the evolution of glass ionomer-resin, the commercial m aterials have these characteristics: ** stronger th a n glass ionomer and w eaker th a n restorative resin; ™ less soluble th a n glass ionomer and more soluble th an resin; ■» fluoride release a t least equal to glass ionomer; easier to use th a n glass ionomer and generally more difficult to use th a n restorative resin; <*» b e tte r esthetic properties th a n glass ionomer b u t usually less acceptable esthetically th an 248
JADA, Vol. 124, July 1993
restorative resin; *■ m olecular bond-to-tooth stru ctu re a t least equal to glass ionomer. G lass ionom er-resin is a versatile m aterial w ith significant potential for dental treatm ent. W hat follows are categories of tre a tm e n t and suggested clinical use of glass ionomer-resin. L IN E R
In the short tim e since intro duction of th e glass ionomerresin Vitrebond, this product has become the m ost popular tooth preparation liner. There has been a significant decrease in th e use of calcium hydroxide as a liner. Recently, liners of any type have been criticized by some clinicians who claim th a t th ere is no need currently for th eir use under any restoration because th e current generation of “dentin” bonding agents are able to seal tooth stru ctu re and decrease tooth sensitivity. Although bonding agents seal tooth stru ctu re w hen used properly, they do not release fluoride or produce subsequent cariostatic influence on teeth. Research has shown th a t fluoride containing glass ionom er-resin liners inhibit sim ulated dental caries activity. Why? At least some m icroleak age still occurs under bonded
resin restorations placed on dentin m argins. Fluoride release from the liner appears to escape to th e outside of the tooth. U ntil fu rth e r research proves otherwise, glass ionom er-resin liners are indicated u n d er restorations having a t least some m argins on dentin. W hat is the optim um liner thickness? Light-cure of current liners is effective up to 2 m illim eters, b u t a t least 0.5 mm is probably an adequate depth for lining am algam or resin restorations th a t have some dentin m argins. F IL L E R
W hen m aking tooth p rep ara tions for crowns or fixed prostheses, void areas in the rem aining tooth stru ctu re are often p resen t w here previous restorations have been removed. Filling these holes w ith thickly mixed traditional glass ionomer or glass ionomerresin provides a nearly ideal replacem ent for m issing dentin. The m aterial bonds to under lying tooth structure, and it does not need m echanical undercuts. It is cariostatic because of fluoride release, and it h as expansion-contraction characteristics sim ilar to tooth structure. Both tradition al glass ionom er and glass ionomer-
CHRISTENSEN) resin are relatively easy to use for th is purpose. B U IL D U P
W hen a significant am ount of tooth stru ctu re is m issing during a tooth preparation for a crown or fixed prosthesis, m ost authorities now recommend building up the rem aining tooth stru ctu re to provide adequate retention for th e subsequent crown restoration. Although traditional glass ionomer is som ew hat w eak for large tooth buildups, glass ionom er-resin is adequate for a t least sm all to m oderate buildup needs. Exam ple strengths of buildup m aterials are: traditional glass ionomer, 18,000 pounds per square inch; glass ionomerresin, 25,000 psi; composite resin, 40,000 psi; and am algam , 60,000 psi. Am algam or composite resin are indicated for larger buildups, retained by pins, undercuts and/or adhesive agents. T O O T H R E S T O R A T IO N S
G lass ionom er-resins are nearly ideal restorative m aterials for patien ts having high need for cariostatic activity. Most often these are pediatric or geriatric patients. These m aterials are especially indicated for p atients for whom new dental caries can be expected unless fluoride release is present in the restor ative m aterial. D entists using glass ionom er-resin restorative m aterial have observed th a t clinical use of these m aterials for restorations is relatively easy, and th a t th e esthetic resu lt is adequate to very good. S trength lim itations and potential w ear characteristics dictate the use of these m aterials m ainly in non
occluding areas (Class 3,5), and in all prim ary tooth classifica tions having m inim al longevity expectations before exfoliation. In the past two years, there have been constant improve m ents in glass ionomer restorative m aterials, and it is expected th a t fu rth er positive changes will be made. These restorations are indicated for situations requiring m oderate strength, high cariostatic activity, m oderate esthetics and relative ease of use. C EM ENTS
Look for the introduction of glass ionom er-resin cement from several companies. The Den-M at products, Geristore and Infinity, have physical characteristics close to glass ionomer-resin, and both are used currently as cements. They do not have a true glass ionomer chemical reaction during setting, but they have been wellDr. Christensen is co-founder and accepted as currently senior easily used, consultant of highly Clinical Research Associates, Provo, retentive, non Utah, and a wellsensitivity known practitioner, researcher and producing international cem ents for speaker. He has a master's degree in situations restorative dentistry needing high and a doctorate in resistance to education and psychology. He is removal. board certified in It is prosthodontics. anticipated th a t soon to be released glass ionom er-resin cements will be significant additions for
cem entation of crowns and fixed prostheses. P R O D U C T S A V A IL A B L E
The following glass ionomerresin products are available now: Fuji II, LC (GC America Inc.); Photac-Fil (ESPE Premier); Variglass (L.D. Caulk/Dentsply); V itrem er (3M). Products sim ilar to glass ionomer-resin, G eristore and Infinity (Den-M at Corp.), have also been promoted and wellreceived for the uses described in th is article. However, m ost people do not categorize these products as glass ionomer-resin, b u t ra th e r as resins containing glass ionomer. Com parisons of these products show varying results, and more tim e is needed for adequate clinical comparisons of b rand nam es. SUMMARY
Glass ionom er-resin is now available from several com panies. The products have been well-accepted for m any uses. Expect continued im provem ents and new product introductions, b ut don’t wait. These products satisfy m any current needs in dentistry. ■ Information about the products mentioned in this article may be available from the author. N either the author nor the American Dental Association has any commercial interest in the products listed. The opinions expressed are those of the author and do not necessarily reflect those opinions or policies of the American Dental Association.
JADA, Vol. 124, July 1993
249