Bonding to tooth enamel has been used in dentistry since 1955, when the concept was first introduced by Buonocore.1 More recent developments in dental adhesives and the involved clinical techniques have enabled practitioners to place aesthetic restorations with favorable bond strengths and greater resistance to microleakage.2,3
The two prevailing techniques in adhesive dentistry today are the total-etch and the self-etch. In the former, whether performed using a three-step or two-step material [Table 1], phosphoric acid is used to preferentially etch enamel and dentin prior to the application of a dental primer and adhesive within the prepared cavity design. This etching process removes the smear layer and opens the dentin tubules for the subsequent penetration of adhesive polymers. The latter (ie, SE technique) does not require a separate etching step and, instead of removing the smear layer, conditions and primes the enamel and dentin layers without rinsing. An SE adhesive partially dissolves hydroxyapatite to produce a resin-infiltrated zone with minerals incorporated.5,6 For the majority of practitioners, SE adhesives are regarded as less technique-sensitive than are TE adhesives.
Postoperative Sensitivity and Restorative Imperatives
For years, postoperative sensitivity has been an undesired outcome to the placement of direct resin restorations in Class I through V cavity designs.7-10 The etiology of postoperative sensitivity has been traced to several factors that include bacterial penetration of the pulp,11 occlusal discrepancies, and deformation of the cusps as a byproduct of polymerization shrinkage stresses.5,9,12 Regardless of its origin, one primary treatment objective for today’s clinicians should be the elimination of postoperative sensitivity. This treatment objective is not in lieu of standard restorative guidelines but is rather an extension of these requisites. Among these imperatives are the following:
- The extent of preparation should be dictated by the amount and location of sound tooth structure present, with the clinician taking care to confine tooth reduction to the elimination of carious tooth structures and creating a cavity design sufficient to withstand the demands of the intraoral environment. Whenever possible, preparations should remain in the enamel. The use of surgical loupes or similar magnification may aid in tooth preparation.
- Bevel enamel margins to conceal the margin, whether using the TE or SE procedure. Leaving the enamel margins roughened will enhance bond strength as well.
- The cavity design should feature rounded internal line angles to improve stress distribution upon placement of the restorative materials through a micromechanical adhesive approach.
- Rubber dam isolation is recommended for proper moisture control at the restorativesite as well as to prevent bacterial or salivary contamination and to reduce airborne debris.
Postoperative sensitivity causes patient discomfort that often predisposes him or her for re-treatment and additional office time. Consequently, the ability of modern adhesive dental approaches to eliminate this sequellae is a considerable benefit to patient and practitioner alike.
(Continued from page 1 )
Adhesive Material Advances
While postoperative sensitivity has been observed with early generations of adhesive materials, subsequent advances in the sixth- and seventh-generation adhesives (Table 1) have minimized the potential of this occurrence and have enabled practitioners to perform adhesive dentistry for their patients with confidence in the long-term result.
In particular, seventh-generation adhesives may help minimize the potential for postoperative sensitivity. Such “all-in-one” materials are indicated for direct and indirect bonding procedures. Formulations that produce a smaller microhybrid layer have less potential for microleakage and thus the transfer of heat, cold, and similar stimuli through the dentin tubules to the pulp and nerve of the tooth is less likely. The result is a restoration with an excellent potential for longevity and pain-free experience for the patient.
It has been suggested that the clinician’s precision in the adhesive procedure has a greater influence on the potential for postoperative sensitivity than does adhesive material selection, and the author generally agrees with this finding. Nevertheless, the ability of the latest generation of adhesive materials to eliminate the technical sensitivities associated with wet bonding can clearly benefit today’s practitioner. Their ease of use, bond strength, and ability to better ensure the comfort of the patient make a compelling argument for use in every restorative dentist’s daily armamentarium.
*Private practice, Fort Lee, NJ
- Buonocore MG. A simple method of increasing the adhesion of acrylic filling materials to enamel surfaces. J Dent Res 1955;34:849-853.
- Swift EJ, Bayne SC. Shear bond strength of a new one-bottle dentin adhesive. Am J Dent 1997;10:184-188.
- Finger WJ, Fritz U. Laboratory evaluation of one-component enamel/dentin bonding agents. Am J Dent 1996;9:206-210.
- Eick JD, Gwinnett AJ, Pashley DH, Robinson SJ. Current concepts on adhesion to dentin. Crit Rev Oral Biol Med 1997;8:306-335.
- Perdigão J, Geraldeli S, Hodges JS. Total-etch versus self-etch adhesive. Effect on postoperative sensitivity. J Am Dent Assoc 2003;134(12):1621-1629.
- Perdigão J, Lopes M. Dentin bonding: Questions for the new millennium. J Adhes Dent 1999;1:191–209.
- Leinfelder KF. Posterior composites. In: Taylor DF, ed. Proceedings of the International Symposium on Posterior Composite Resins. Chapel Hill, N.C.: University of North Carolina Press; 1984:353.
- Eick JD, Welch FH. Polymerization shrinkage of posterior composite resins and its possible influence on postoperative sensitivity. Quint Int 1986;17:103-111.
- Christensen G. Preventing postoperative tooth sensitivity in Class I, II, and V restorations. J Am Dent Assoc 2002;133:229-231.
- Opdam NJ, Feilzer AJ, Roeters JJ, Smale I. Class I occlusal composite resin restorations: in vivo post-operative sensitivity, wall adaptation, and microleakage. Am J Dent 1998;11:229-234.
- Brännstrom M. Etiology of dentin hypersensitivity. Proc Finn Dent Soc 1992;88(Suppl1):7-13.
- Pashley DH, Tay FR. Aggressiveness of contemporary self-etching adhesives, part II: Etching effects on unground enamel. Dent Mater 2001;17:430-444.