Why does the subject of postoperative tooth sensitivity in Class I, II and V restorations keep resurfacing? It probably is because these restorations are among the most common treatment procedures dentists accomplish, and many of the dentin-bonding concepts are overpromoted in terms of preventing postoperative tooth sensitivity.
Frequently, participants in my restorative dentistry courses ask questions about prevention of postoperative tooth sensitivity in Class I, II and V resin-based composite restorations. It is not clear why Class III and IV restorations are not sensitive. In explaining the potentially sensitivity-preventing procedures, I find that because of time limitations, I commonly emphasize one method or another, instead of listing the several ways in which the sensitivity can be prevented.1–3
This article describes several ways to prevent postoperative tooth sensitivity in teeth restored with Class I, II and V resin-based composite restorations. The suggestions are based on empirical evidence provided by dentists in my courses, as well as my personal observations.
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PERFECT USE OF TOTAL-ETCH SYSTEMS
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Many dentists use the well-known total-etch concept on a routine basis. If the total-etch technique is mastered, tooth structure can be sealed adequately to preclude postoperative sensitivity.
How does a dentist use the total-etch technique perfectly? Tooth surfaces are etched for about 15 seconds; the acid is washed from the tooth and the tooth surface is dried only superficially, leaving slight moisture on the surface; the primer solution is applied in coats sufficient to allow impregnation of the primer liquid into the dentinal canals; the bonding solution is applied, blown slightly and cured adequately with a curing light. The specific techniques used for different total-etch products vary from brand to brand.
Practitioners have observed several challenges with the total-etch concept. Among them:
- – it is easy to dry tooth surfaces too much before applying the primer solutions;
- – it is difficult to apply the primer solution in coats sufficient to provide impregnation of the liquid into the dentinal canals;
- – if the bonding solutions are blown too thin, which can happen easily, the bonding resin will not cure properly because of the oxygen-inhibition.
Total etching is acceptable if it is carried out perfectly, but dentists constantly report to me that some of their patients experience postoperative tooth sensitivity when they, the dentists, believe they have carried out the total-etch procedure exactly as manufacturers recommend. Can improvements or modifications be made in the total-etch concept?
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IMPROVING THE TOTAL-ETCH CONCEPT
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Tooth-desensitizing solutions.
Tooth-desensitizing solutions can improve the total-etch technique. These solutions should be used after acid etching is completed and the tooth surfaces are dried slightly. Wetting of the tooth surfaces provided by the hydroxyl ethyl methacrylate in the desensitizing solutions, and the subsequent drawing of the bonding resin into the dentinal canals, appear to reduce tooth sensitivity significantly. One popular desensitizing solution is GLUMA (Heraeus Kulzer, South Bend, Ind.), but other products also have been reported to be effective, including MicroPrime (Danville Materials, San Ramon, Calif. ), Tubulicid (Global Dental Products, North Bellmore, N.Y.) and HurriSeal (Beutlich Pharmaceuticals, Waukegan, Ill.).
Flowable resins.
Dentists in many of my continuing education courses have reported to me that that placement of flowable resin after the completion of the previously described steps of the total-etch concept reduces sensitivity. This technique has become very popular because of its simplicity. After placing and curing the bond ingredient of the standard bonding agent, the practitioner places and cures a thin layer of flowable resin. This flowable resin layer is thicker than the standard layer of bonding agent. The flowable resin provides a buffer between the tooth and the restorative material, and it potentially obturates any areas of inadequate seal between the previously placed bonding agent and the acid-etched dentin.
High-viscosity bonding agents.
Several total-etch bonding agent brands have a high viscosity that approximates that of flowable resins. Examples of these products are Opti-Bond Solo Plus (Kerr Dental, Orange, Calif.), PQ1 (Ultradent Products, South Jordan, Utah) and One Coat Bond (Coltène/ Whaledent, Mahwah, N.J.). Dentists have reported to me that the use of these products has reduced postoperative tooth sensitivity.
Can improvements or modifications be made in the total-etch concept?
Using multiple layers of bonding agent.
This technique is similar to the previous two procedures. When a layer of bonding agent is thinned by an air blast, it may be insufficiently thick to cure properly because of oxygen inhibition. As a result, the unfilled resin bonding agent may not seal the dentin. When more than one layer of unfilled bonding agent is applied to the etched tooth surface and each layer of bond is cured separately, there is a greater chance of the bond layers’ being sufficiently thick to seal the acid-etched dentinal canals. Additionally, the thicker layer of unfilled bonding agent provides a flexible layer of resilient resin between the tooth and the restorative resin. Dentists report that this procedure reduces or eliminates postoperative tooth sensitivity.
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SELF-ETCHING PRIMERS
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In my opinion, the most significant advancement in bonding agents in many years has been the introduction of self-etching primers. These bonding agents do not remove the smear layer. The smear layer is left in place and impregnated with a wetting agent and unfilled resin. The resultant combination of smear layer, wetting agent and unfilled resin creates plugs in the dentinal canals, and many dentists have reported to me that there it almost totally eliminates postoperative tooth sensitivity. That has been my own experience with many hundreds of restorations.
Changing from the total-etching to the self-etching technique is not difficult, except in that dentists and staff members must remember to avoid any moisture contamination of the tooth surfaces. If moisture contamination occurs, the tooth must be treated as though a total-etch system has been used.
Representative products included in the self-etch category are Clearfil Liner Bond 2V and Clearfil SE Bond (Kuraray America, New York City), Prompt L-Pop (3M ESPE, St. Paul, Minn.), Touch & Bond (Parkell, Farmingdale, N.Y.) and One-Up Bond F (J. Morita, Irvine, Calif.).
The self-etching concept can be used alone or with other techniques described above; I will state my preferred combination of techniques later in this article.
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RESIN-REINFORCED GLASS IONOMER LINERS
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Many years ago, a combination of glass ionomer and resin was introduced to be used as a luting cement, liner and restorative material. The resultant resin-reinforced glass ionomer materials, used as crown and fixed-prosthesis cements, have been shown effective in preventing postoperative tooth sensitivity. Similarly, when this type of material (Vitrebond, 3M ESPE, St. Paul, Minn., or GC Fuji Lining Cement LC, GC America, Alsip, Ill.) is applied to the deepest portions of Class I, II and V tooth preparations before any bonding systems are used, clinicians have reported to me that it almost totally prevents postoperative tooth sensitivity. In my own clinical experience, this technique is one of the most predictable methods of preventing postoperative tooth sensitivity.
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COMBINATIONS OF THE ABOVE TECHNIQUES
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When postoperative tooth sensitivity is expected, combining two or more of the previously described desensitizing techniques may be necessary. Numerous combinations of the methods have been described and supported by clinicians.
The combination technique that I have used with nearly 100 percent success follows:
- – tooth preparation;
- – placement of thin (about one-half millimeter–thick) resin-reinforced glass ionomer liner on deepest dentin surfaces;
- – use of self-etching primer (such as Kuraray SE Bond, Kuraray America, New York City) without previous use of standard acid etching;
- – placement and cure of resin-based composite.
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SUMMARY
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Postoperative tooth sensitivity in Class I, II and V resin-based composite restorations continues to be an unpredictable problem in dentistry. In spite of meticulous use of dentin bonding agents, dentists and patients are faced with the sensitivity problem and the frustrating need to remove restorations and occasionally accomplish endodontic therapy on teeth that were not sensitive before the restorations were placed. Practitioners have developed numerous preventive methods to overcome the sensitivity challenge, which I have described in this article.
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PERFECT USE OF TOTAL-ETCH...
IMPROVING THE TOTAL-ETCH CONCEPT
