Ask the Experts

DENTIN BONDING, CARIES CONTROL

Associate Editor Edward J. Swift Jr., DMD, MS

QUESTION: I accidentally discov- ered that Gluma One Bond does not set to a “hard” state when light-cured on a pad. Even when blown very thinly, an oily residue remains. In contrast, 3M Single Bond does cure hard. My obvious concern is that there is an uncured interface between the luting agent and the composite that would affect the long-term viability of these restorations. Could you please comment on this situation and, if possible, allay my anxiety that these restorations are doomed?

DR. SWIFT: That is a good question. I am not sure that I can give you a definite explanation about what is happening, but I can give you an educated guess.

As you know, methacrylate resin polymerization is inhibited by oxy- gen. That is why, when you place a sealant, the surface feels sticky. This is certainly not a bad thing-it is

what allows one to build up com- posite in layers, with the layers actually adhering to each other.

Adhesives also have an air-inhibited surface layer that allows bonding of the composite to the adhesive. To my knowledge, this is something that has not been studied in detail, but it seems that different adhesives will have different degrees of air inhibition. Here is where my edu- cated guess comes in-the Gluma One Bond probably is more inhib- ited by oxygen than Single Bond is. 3M Dental Products uses a slightly different photoinitiator system than most other manufacturers, and it is quite efficient.

The good news is that the Gluma One Bond is almost surely curing completely after the composite is placed over it. I sincerely doubt that your restorations will have problems related to what you have seen,

SUGGESTED READING Swift EJ Jr, Perdigio J, Heymann HO. Bonding to enamel and dentin: a brief his- tory and state of the art. Quintessence Int 1995; 26:95-110.

Walshaw PR, McComb D. Clinical con- siderations for optimal dentin bonding. Quintessence Int 1996; 27619425.

Haller B. Recent developments in dentin bonding. Am J Dent 2000; 13:44-50.

Tulunoglu 0, ifgtash M, Alagam A, bniirlii H. Microleakage of light-cured resin and resin-modified glass ionomer dentin bonding agents applied with co-cure vs. pre-cure technique. Oper Dent 2000; 25:292-298.

QUESTION: I am treating a patient who is in the late stages of multiple sclerosis. Owing to dry mouth and declining dexterity, he is undergoing root caries at an accelerated pace. He refuses the use of amalgam. Many of the areas of decay are on the lingual of lower molars, and field control is a problem. He is using a home fluoride regime as well as artificial saliva. Neverthe- less, recurrent caries is appearing around composite restorations.

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What alternative materials do you recommend?

DR. SWIFT: Although laboratory studies uniformly indicate that glass ionomers reduce the frequency and severity of recurrent caries, clinical studies are less conclusive. Still, some type of fluoride-releasing material may be beneficial in this case.

In considering fluoride-releasing materials, there are essentially four choices: composites, compomers, glass ionomers, and resin-modified glass ionomers. Fluoride-releasing composites are few in number, and generally do not release as much fluoride as the other materials, so I

which are essentially modified com- posites, do release fluoride and can be “re-charged” with topical appli- cations to some extent. 2.

Glass ionomers and resin-modified glass ionomers are a bit less user- friendly than the composite materi- als. However, they tend to release more fluoride and can be re-charged more easily. Conventional glass ionomers (e.n., Fuji IX GP, GC

3.

4.

Berg JH. The continuum of restorative materials in pediatric dentistry: a review for the clinician. Pediatr Dent 1998; 20:93-100.

McLean JW. Dentinal bonding agents ver- sus glass-ionomer cements. Quintessence Int 1996; 276594567.

Carvalho AS, Cury JA. Fluoride release from some dental materials in different solutions. Oper Dent 1999; 24:14-19.

Randail RC, Wilson NHF. Glass-ionomer restoratives: systematic review of a sec- ondary caries treatment effect. J Dent Res 1999; 78:628-637.

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America, Chicago, Illinois) do not require light-curing, which can be a real advantage where curing-light access is limited. This particular material also seems to tolerate rela- tively poor field control.

02000 BC Decker Inc

Editor’s Note: If you have a question on any aspect of esthetic dentistry, please direct it to the Associate Editor, Edward J. Swift Jr., DMD, MS. We will forward questions to appropriate experts and print the answers in this regular feature.

Ask the Experts Edward J. Swift Jr., DMD, MS Department of Operative Dentistry University of North Carolina, CB#7450, Brauer Hall Chapel Hill, NC 27599-7450 Telephone: 919-966-2773; Fax: 919-966-5660 E-mail: Ed-Swift@dentistry.unc.edu

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would rule those out. Compomers, SLJGGES'rED R E A D I N G