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J O U R N A L OF ESTHETIC D E N T I S T R Y
Ask the Experts
BLEACHING, DENTIN BONDING
Associate Editor Edward J. Swift Jr., DMD, MS
DR. JIM FARMER, Charlottesville, Virginia: Are reservoirs necessary for bleaching trays?
D R . V A N B. HAYWOOD*: The answer to this question depends on the bleaching material, tray design (based on patient conditions and concerns), and the extent of wear anticipated. Reservoirs are an Ultradent-patented feature designed to allow complete seating of a tray containing a viscous bleaching material, such as Opalescence, and other similar materials. Reservoirs also avoid the pinching effect of the tray, by eliminating contact on one side, and may reduce the chances of tooth sensitivity. Products with a thin creamy consistency (e.g., Colgate Platinum Overnight) do not require reservoirs for any reason.
Clinical research has shown that reservoirs are not needed for effi- cacy of bleaching, because they do not speed up the rate of lightening. However, reservoirs may prolong the activity of the peroxide con-
tained in viscous gel materials. A recent in vivo study of several bleaching materials without reser- voirs reported that only minimal material remained in the tray after 4 hours. However, a similar in vivo study using Opalescence with reservoirs reported the presence of active material in the tray even after 10 hours.
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Haywood VB. Nightguard vital bleaching: current concepts and research. ] Am Dent ASSOC 1997; 128 (Suppl):l9~-25~.
Haywood VB, Leonard RH, Dickinson GL. Efficacy of six-months' nightguard vital bleaching of tetracycline-stained teeth.] Esthet Dent 1997; 9:13-19.
Heymanti HO, Swift E], Bayne SC, et al. Clinical evaluation of two carbamide per- oxide tooth-whitening agents. Com- pendium 1998; 19:359-376.
Christensen G]. Tooth bleaching. state-of- art '97. CRA Newsletter 1997; 21:l-3.
Gaiao U, Matis BA, Cochran MA, Bhck- man D, Schultz F. Cliniccll study o f 10% carbamide peroxide degradation in bleach- ing trays. ] Dent Res 1998; 77:135. (Abstr)
*Professor, Department of Oral Rehabilita- tion. Media l College of Georgia, Augusta, Georgia
D R . J A N DELORRY-LYTLE, King
George, Virginia: HOW is dentin bond- ing affected by caries indicator dyes?
DR. MARCOS A. VARGAS*: Caries detection dyes are designed to stain the irreversibly altered organic matrix of demineralized dentin. Little is known about their effects on bonding of resin to dentin. However, a study reported at a 1997 research meeting found that caries detectors reduced the bond strength of two adhesive systems to sound dentin. Another study has reported that the type of dye did not affect tensile bonds to dentin.
A more recent study evaluated bonding between resins and artifi- cially demineralized dentin. Bond strengths were low, as might be expected, but the use of caries detec- tors had no effect on bond strengths.
In summary, there is some evidence that caries detectors reduce the bond of resin to sound dentin. However, if all caries is not removed during
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J O U R N A L O F E S T H E T I C D E N T I S T R Y
cavity preparation, bonding to the remaining demineralized dentin is poor. Bonds to sound dentin are
S U G G E S T E D R E A D i N c 3. Xie J , F la i t z CM, Hiaks MJ, Powers JM. Bond strength of composite to sound and artificial curious dentin. Am J Dent 1996; 1. Palma RG, Xurbino ML, Matson E,
Powers JM. Bond Strength to dentin with artificial carious lesions: influence of curies detecting dye. Am J Dent 1998;
9:31-33.
much better, so if the caries detector 11:128-130. '
helps to Provide a noncarious sub- strate, any reduction in bond
2. Demarco FF, MntOs AB, Matson €, powers JM. Dyes for caries detection influence sound dentin bond strength. J Dent Res 1997; 76:417. (Abstr)
*Associate Professor, Department of Opera- tive D"'tkhy, un'versib' of lows, Iowa city- Iowa 01 999 B.C. Decker lnc. strength as a result of its use is
probably acceptable.
Editor's Note: If you have a question on any aspect of esthetic dentistry, please direct it to the Associate Editor, Dr. Edward J. Swift. We will forward questions to appropriate experts and print the answers in this regular feature.
Ask the Experts Dr. Edward J. Swift Jr. 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: [email protected]
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