Composites and Whitening: How and When to Combine Treatments

Gerard Kugel, DMD, MS, PhD; Susana Ferreira, DDS; and Ronald Perry, DMD, MS

Gerard Kugel, DMD, MS, PhD; Susana Ferreira, DDS; and Ronald Perry, DMD, MS

Given the objective of today’s conservative dentistry to save tooth structure, it is common to combine direct composite restorations and tooth whitening to achieve esthetically pleasing clinical results that also limit the necessity for prosthodontic tooth preparation. Clinicians must consider, however, that with whitening and composites, a certain methodology is necessary to prevent potential failure inherent to this combination. Addressing issues ranging from concerns over loss of tooth structure to lack of funds for prosthodontic work, direct composites and whitening are logical and ideal treatment options dentists can recommend for numerous patients. The authors present one such case study to demonstrate the benefits that are possible when such a course of treatment is properly performed.

Dental research shows the bond strengths of adhesives to bleached hard tissues can be temporarily reduced in some cases.¹ The literature states that surface softening and roughening of restorative materials is a concern, particularly in composite.² However, in this age of the popular concept of conservative dentistry to save tooth structure, it has become very common to combine direct composite restorations and tooth whitening to achieve an esthetic clinical result while limiting the need for prosthodontic tooth preparation.³ To marry the two principles—the benefit of combining whitening and composite restorations with the potential for surface degradation in doing so—for ideal treatment and case planning, clinicians should use an evidence-based approach to esthetic treatment.

It is important for clinicians to understand why methodology is important for the use of whitening and composites in clinical practice. Industry researchers studied bond strengths incessantly over the last 15 years, which led to the modification of products, systems, and techniques for the betterment of dentistry. It is of clinical importance not to undermine that progress with whitening materials, which are intended to enhance dental practitioners’ work, not hinder it.

The reduction in composite bond strength to bleached dentition can be attributed to several factors; some are considered common knowledge among dentistry’s clinical peers while others are more esoteric to research circles. The former is comprised of the following: residual oxygen often inhabits the enamel and dentinal pores post-bleaching; once liberated, the oxygen molecules could prevent adequate resin infiltration into dentin and enamel⁴ and/or inhibit resin polymerization of those that cure using free-radical mechanisms.⁵ The ultimate result could be debonding of the restorative material as a result of a soft interface between hard tissues and composite caused by oxygen-inhibited polymerization.⁶

The latter factors, often not discussed in clinical lectures or literature, relate to changes in enamel morphology that weaken bond strengths subsequent to whitening. Hydrogen peroxide and its releasing agents may result in decreasing levels of enamel calcium and phosphate in addition to changes in form and structure of the most superficial crystallites in enamel.⁷ The clinical consequence of these factors is not only potential debonding, but also an enamel surface that appears over-etched; bleached enamel submitted to acid-etching produces a deficit of prismatic form, leaving the restoration less esthetic than intended.⁸ It is important to note that the potential negative effects of whitening on restorative materials are not limited to the surface of a tooth; layers beneath the surface are equally at risk. Polishing the bleached surface of an adhesive material may not suffice to reinstate the physical properties of the fillings.⁹

Clinically, it is imperative to incorporate the potential risks to new restorations into treatment planning to stave off clinical failure, patient dissatisfaction, and their corollary relationship to the economic consequences of redoing composite restorations. The literature is rife with studies suggesting a lapse between the completion of whitening therapy and the placement of composites (and orthodontic brackets). Because adhesion of resin to bleached enamel is compromised for up to 14 days after bleaching, a 2- to 3-week waiting period is suggested.¹⁰ Furthermore, the necessity to avoid bonding to older composite restorations is commonly understood.

The following case outlines a series of restorations provided to a patient who presented in the clinic at Tufts University School of Dental Medicine in Boston. The authors, using a team approach to diagnosis, decided to restore the patient’s mouth in stages using a combination of caries control, whitening, direct composites, and single crowns. The authors elected to perform the dental procedures at a price point well below the affordability of the patient to make a case study of his condition and restorations. The patient understood the ramifications of treatment, as well as the alternatives to the therapies proposed in the treatment plan.

CLINICAL CASE
The patient was a 40-year-old man with no medical contraindications to treatment. The patient underwent a comprehensive examination and a full-mouth set of radiographs for screening purposes (Figure 1 View Figure ; Figure 2 View Figure ; Figure 3 View Figure ). The authors found generalized rampant decay with a more profound incidence on the maxillary arch. Immediate caries control was deemed necessary to allow the patient to start whitening at home as part of his overall treatment plan. The authors decided on an initial treatment plan for the maxillary arch consisting of the following: crown teeth Nos. 7 and 8 and restore teeth Nos. 11 and 12 immediately for caries control; let the patient whiten for a period of 10 days; allow the patient to wait for 2 weeks before doing cervical composites on teeth Nos. 5, 6, 9, and 10. Pending finances, the posterior teeth and the mandibular arch were relegated to phase two of the patient’s treatment plan.

Teeth Nos. 7 and 8 were prepared and provisionalized for zirconia restorations. At the time of the initial visit, the average tooth shade (VITA Shade Scale, Vident^™, Brea, CA) on the maxillary anterior teeth was determined to be A3.5 in value order. Anticipating effects from whitening, a temporary crown shade of A2 was selected. This same shade was chosen for the composite material on teeth Nos. 11 and 12.

Tooth No. 11 was treated for cervical decay using a Class V composite preparation (Figure 4 View Figure ). The tooth was etched with an etchant (Ultra-Etch^™, Ultradent Products, Inc., South Jordan, UT) and bonded with a bonding agent (Adper^™ Singlebond^™, 3M^™ ESPE^™, St. Paul, MN), then restored with an A2 shaded enamel composite (4 Seasons, Ivoclar Vivadent, Amherst, NY). Tooth No. 12 had a pre-existing mesial-occlusal-distal composite restoration with marginal leakage and was described as uncomfortable by the patient. Also, a Class V preparation was necessary to restore the decay in the cervical area. Both restorations on tooth No. 12 were placed using the same armamentarium as tooth No. 11. All composites were finished using a finishing bur (ET Finishing Burs, Brasseler^® USA, Savannah, GA) and polished with a polishing kit (CompoSite^® Polishing Paste, Shofu Dental Corporation, Menlo Park, CA).

At that initial visit, the patient was prescribed a 10-day treatment of a take-home whitening system (Opalescence Trèswhite Supreme, Ultradent Products, Inc., South Jordan, UT) and an over-the-counter sensitivity dentifrice. This type of whitening was chosen because of the gratis nature of the case and the product’s particular convenience as it afforded the patient the opportunity to skip a visit to receive whitening trays in an already taxing clinical appointment schedule.

After 5 days of whitening, the patient presented for a coping try-in for the anterior crowns (Figure 5 View Figure ). At that visit, the patient complained of extra sensitivity on teeth Nos. 9 and 10. It was hypothesized that the cause of this sensitivity was two-fold: many carious lesions and transient sensitivity common in whitening; examination excluded pulpal involvement. The clinicians agreed on the need for caries control using immediate composites on those two teeth (Figure 6 View Figure). The temporary restorations were placed using the previously used shade A2 enamel composite, with the expectation that the composites would be redone at the crown insertion appointment so that shade matching among the anterior teeth would be possible (Figure 7 View Figure).

The patient resumed whitening for another 5 days to complete the full treatment (Figure 8 View Figure). Two weeks after completing the home whitening, the patient returned to the school for shade selection of the anterior crowns. It was important to wait for the teeth to rehydrate because a slight relapse in color is expected immediately after external whitening.¹¹ An average shade of A2 was selected for the crowns, with some variations in the hue and chroma at different points on the body of the crowns (Figure 9 View Figure). The composite restorations were not placed on this date because the final crowns—needed for use as a reference to match the anterior composites—were not finalized.

Three days later, after an expedited laboratory fabrication, the crowns for teeth Nos. 7 and 8 were cemented, the composites on teeth Nos. 9 and 10 were replaced, and a pre-existing defective restoration on tooth No. 6 was removed and the tooth was restored (Figure 10 View Figure and Figure 11 View Figure). The authors were comfortable with this treatment date given the 2-week span necessary to maximize the adhesion of the new resin to the bleached enamel. The crowns were placed in the mouth without cement initially to facilitate shade matching and contouring of the adjacent composites. Both composite restorations on teeth Nos. 9 and 10 were placed using an etchant (Ultra-Etch), a bonding agent (Adper Singlebond), and A2 dentin shade of composite (4 Seasons) on the cervical margin; an A1 enamel shade of composite (4 Seasons) was layered over the cervical and onto the body toward the incisal edge. The incisal was restored using a custom medium translucent shade of composite (4 Seasons). The composite restorations were finished with the burs (ET Finishing Burs) and polished with a polishing paste (CompoSite^® Polishing Paste).

At this visit, the needs of tooth No. 5 were addressed to remove the cervical and mesial decay, and in tooth No. 6, which had cervical decay and a pre-existing distal/lingual defective retoration. These teeth were restored using the same etchant and bonding agent as the previous teeth, and the authors layered shade A2 dentin composite (4 Seasons) on the cervical margin and an A2 enamel shade (4 Seasons) on the remainder of the affected area. These teeth were finished and polished in the same manner.

At that point, the crowns were inserted and the patient was instructed to return in 1 week for observation (Figure 12 View Figure ; Figure 13 View Figure; Figure 14View Figure ; Figure 15 View Figure). The patient expressed overwhelming satisfaction with the results and is expected to return for further treatment on the mandibular arch (Figure 16 View Figure and Figure 17 View Figure).

CONCLUSION
Studies evaluating the effects of whitening therapies on the hardness and morphology of dental restorative materials are prevalent. Although the results of the numerous trials vary regarding the scope and severity of the effects, most researchers and clinicians agree that some deleterious outcomes are possible, if not probable. A conservative strategy for esthetic dentistry, a combined treatment of whitening and composite re-storations, may be ideal for many patients. Dentists must keep in mind that with whitening and composites, a certain methodology is necessary to ensure against the potential failure inherent to this combination. Addressing issues ranging from concerns over loss of tooth structure to lack of funds for prosthodontic work, direct composites and whitening are logical and ideal plans for many patients.

In this case study, the authors admittedly only have begun to restore this patient to optimum function and esthetics; posterior maxillary teeth and the full mandibular arch still must be addressed. The patient will be monitored at Tufts University School of Dental Medicine on an ongoing basis. The authors understand that crown-and-bridge procedures may be a likely outcome in the future, but consider their treatment plan ideal for this individual patient at this point in time.

As a team, the authors had several discussions over the sequencing and timing of the different treatment steps in this plan. Perhaps the most important point decided was the 2-week lapse between the final whitening and the application of new composite materials; this was done in an attempt to minimize the possibility of debonding from soft surface structure and roughness. Ultimately, conservative measures resulted in a highly satisfied patient with an interesting case study.

ACKNOWLEDGMENTS
The authors would like to thank Dr. Shradha Sharma of Tufts University and John Orfanidis of Orfan Dental Laboratory for their clinical assistance with this case, in addition to Jennifer Towers of Tufts University for her editing and grammatical composition, which was very much appreciated.

REFERENCES
1. Cavalli V, Reis AF, Giannini M, et al. The effect of elapsed time following bleaching on enamel bond strength of resin composite. Oper Dent. 2001;26: 597-602.

2. Attin T, Hannig C, Wiegand A, et al. Effect of bleaching on restorative materials and restorations—a systematic review. Dent Mater. 2004;20:852-861.

3. Deliperi S, Bardwell DN. Two-year clinical evaluation of nonvital tooth whitening and resin composite restorations. J Esthet Restor Dent. 2005;7:369-378.

4. McGuckin RS, Thurmond BA, Osovitz S. Enamel shear bond strengths after vital bleaching. Am J Dent. 1992;5:216-222.

5. Rueggeberg FA, Margeson DH. The effect of oxygen inhibition on an unfilled/filled composite system. J Dent Res. 1990;69: 1652-1658.

6. Cadenaro M, Breschi L, Antoniolli F, et al. Influence of whitening on the degree of conversion of dental adhesives on dentin. Eur J Oral Sci. 2006;114:257-262.

7. Perdigao J, Francci C, Swift EJ Jr, et al. Ultra-morphological study of the interaction of dental adhesives with carbamide peroxide-bleached enamel. Am J Dent. 1998;11: 291-301.

8. Josey AL, Meyers IA, Romaniuk K, et al. The effect of a vital bleaching technique on enamel surface morphology and the bonding of composite resin to enamel. J Oral Rehabil. 1996;23:244-250.

9. Attin T, Buchalla W, Wiegand A. Adhesion, ceramics and bleaching—a critical evaluation. Academy of Dental Materials Transactions. 2006;20:132.

10. Titley KC, Torneck CD, Ruse ND, et al. Adhesion of a resin composite to bleached and unbleached human enamel. J Endod. 1993;19:112-115.

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FIGURE 1 Preoperative view of a fully retracted smile of a 40-year-old patient with no medical contraindications to the treatment plan. After examination, the authors selected an initial average shade.		FIGURE 2 Part of the comprehensive examination included a full-mouth set of radiographs and preoperative right lateral views of the patientas teeth.
FIGURE 3 Preoperative left lateral views were also included as part of the comprehensive examination.		FIGURE 4 Caries control was performed on tooth No. 11. In this procedure, a lighter shade was selected to match the tooth after the whitening process.
FIGURE 5 Five days after initial whitening treatment, the patient presented for a coping try-in for the anterior crowns.		FIGURE 6 Caries control was performed on teeth Nos. 9 and 10 during whitening treatment because of sensitivity.
FIGURE 7 Caries control was performed on teeth Nos. 9, 10, and 11.		FIGURE 8 Whitening treatment resumed on day 10.
FIGURE 9 Final shade selection for the crowns and composite restorations was made 2 weeks after bleaching treatment.		FIGURE 10 At the final visit, the provisional crown preparations and caries control composites were removed. Note that the caries on tooth No. 11 has also been addressed.
FIGURE 11 Lingual view of the prepared teeth at the time of the patientas final visit.		FIGURE 12 After the crowns were inserted, teeth Nos. 7 and 8, as well as the final composite restorations on teeth Nos. 5, 6, 9, 10, 11, and 12, were completed.
FIGURE 13 Postoperative left lateral view exhibits satisfactory results.		FIGURE 14 Postoperative right lateral view demonstrates an esthetically satisfactory outcome to the treatment plan.
FIGURE 15 Postoperative occlusal view of the maxillary arch exhibits satisfactory results.		FIGURE 16 As evident from this preoperative maxillary arch view of the patientas smile, considerable work was needed.
FIGURE 17 The patient was overwhelmingly satisfied with the results of the authorsa work, which can be appreciated in this postoperative smile view of patientas maxillary arch treatment.