Direct composite resin inlay

SECTIONEDITORS

Direct Jason

corn D. Biederman

Greenvale,

N.U.

Posterior composite resin restorations have several physical limitations. Polymerization shrinkage during curing and resistance to wear are two factors that can be alleviated by a composite resin inlay. Curing the restoration extraorally in a heat-and-light curing unit and cementing the restoration with a composite resin cement reduces the deleterious effects of polymerization shrinkage and increases wear resistance of the material. A metho to make a direct composite resin inlay is detailed.(J PROSTHETDENT ~~$~g~249-~~.)

T

here has been a dramatic increase m the number of posterior composite resin restorations with public awareness in esthetics. Tlowever, posterior composite resin restorations have many limitations. Understanding the physical properties of composite resins and providing resolutions to compensate for the polymerization shrinkage, wear, and viscosity will improve posterior composite resins. Lambrechts et a1.l stated that polymerization shrinkage of the composite resin during curing compromised the composite resin-tooth bond. Polymerization shrinkage does not usually cause microleakage in conservative restorations (Fig. 1) with enamel etching if the marginal adbesion is greater than the polymerization shrinkage. Tbe volume of composite resin increases with large restorations so that shrinkage forces prevail, producing marginal openings despite enamel etching. Davidson and deGee2 discovered that contraction forces caused by polymerization shrinkage developed internal stresses, producing cracks in tbe enamel. Contraction forces of this magnitude could contribute to postoperative sensitivity, pain, or discomfort on chewing. Jensen and Chan3 and Robinson et al.4 suggested that acceptable gins were obtained only with composite resin inlays with adhesive resins. With the posterior composite resin inlay technique the quantity of composite resin Ming agent polymerized intraorally is minimal, diminishing undesirable shrinkage. Composite resin wear can be attributed to attrition and abrasion. Attrition occurs during occlusal contact, with loss of material and facet formation resulting from direct tooth contact at the centric stop. Abrasion results from the wear caused by tooth brushing or by chewing food without direct contact between the restoration and the opposing to0th.i Wendt5 found that wear resistance and hardness were increased by using a second cure with beat. The consistency of composite resin material does not allow predictable proximal contacts. The fabrication of

Fig. 1. Small class II composite resin :estoration on distd surface of second premolar. A, Preparation completed; f restoration completed.

direct or indirect inlays encourages appropriate proximal contacts by allowing additions in deficient contact areas, repair of voids, and well-finished surfaces.

ETHOD Restorative methods and materials must be modified to ensure a superior posterior composite resin restoration. A recent approach is the direct composite resin inlay that

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Fig. 2. Mandibular second premolar before replacement of disto-occlusal amalgam with composite resin inlay. Fig. 3. Lubricated round wooden toothpick used to separate tooth and protect rubber dam. Fig. 4. Completed inlay cavity preparation with glass-ionomer cement liner. Fig. 5. Cure-Thru matrix band and reflective wedge. Fig. 6. Rough carved composite resin inlay before curing with visible-light unit. Fig. 7. Curing composite resin inlay with visible-light unit. usesa light-cured, radiopaque hybrid composite resin, a light-: and-heat curing oven, and a separating medium (Brill iant D.I. 500 direct inlay system, Coltene Inc., Carlsbad, f >alif.). The separating medium Brilliant D.I. Separator is unique and is a prerequisite in this technique. Tht 3 treatment sequence is as follows. 250

1. Administer a local anesthesia and while it is reachirIg full effect, clean the tooth with a nonfluoride pro1,hylactic paste. Select a shade after completion of the prophylaxis of the tooth (Fig. 2). 2. Place an extra-heavy textured rubber dam.” 3. Insert a round wooden toothpick, lubricated with liq-

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Fig. Pig. Fig. Fig.

4.

5.

6. 7.

8.

9.

THE

8. Removing preliminary contoured restoration with plastic instrument. 9. Composite resin inlay with contour and appropriate contact area. 10. Light-and-heat curing unit with. compartment. II. Etched enamel and glass-ionomer cement liner before cementation.

uid soap, between the tooth to be preparea and the adjacent tooth for separation and protection of the rubber dam (Fig. 3). Prepare the tooth as a classic intraoral casting with the exception of slightly rounded internas angles without cavosurface bevels. The cured composite resin material dictates butt joints because it is subject to fracture in thin layers. Apply a calcium hydroxide liner and glass-ionomer cement liner over the dentinal surface. Trim the glassionomer cement liner to remove undercuts, and clean the cavosurface margins (Fig. 4). Introduce the separating medium into the cavity preparation with a brush. Place a transparent matrix band and a clear light-reflecting wedge (Premier Cure-Thru Reflective Wedge System, Premier Dental Products Co., Norristown, Pa.) on the prepared tooth (Fig. 5). Repeat the application of separating medium specifically in the cavity preparation and the entire tooth Disperse the separating medium into a thin layer with a gentle stream of air. Place the composite resin into the cavity preparation

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10. II.

12. 13. 14. 15. 16.

ilford, Corm.) with a Centrix-CR III (Centrix Inc., syringe. Contour the surface of the composite resin by using iubricated carving instruments (Fig. 6). Polymerize the light-cured composite resin in the cavity preparation by using a conventional visibie-light curing unit. The first cure requires 60 seconds from the cervical direction on the wedge and the secon directed to the occlusal surface for 60 to 120 seconds (Fig. 7). Remove the matrix band and wedge from the tooth. Gross finish the light-cured composite resin inlay with a carbide finishing bur in a high-speed handpiece, Remove the composite resin inlay from the cavity preparation with a pointed instrument (Fig. 6). Relieve axial walls of inlay with carbide finishing burs. Finish contouring the proximal and occlusal surfaces of the inlay. If there is need for additional composite resin, the procedure is as follows: (a) Lightly abrade area for the addition with a diamond bur. (b) Wash off with water/air spray and dry.

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Fig. 2. Pig. 13. Pig. 14. removed. Pig. 15.

17. 18. 19.

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Etched internal surface of composite resin mlay. Composite rssin imay with excess cement at margins. Finished composite resin inlay with excess cement and Oxyguard Completed

material

inlay during occlusal refinement.

(c) Etch the area with 37 % phosphoric acid for POseconds, then rinse and dry. (d) Add bonding agent and disperse with gentle air pressure for a thin, uniform layer. (e) Add composite resin and develop the contour. (f) Cure the addition witk a conventional visible-light curing unit. (g) Complete contouring of cured composite resin addition. Reseat the inIay and check eontours, contacts, and margins. Complete the corrections at tbis time (Fig. 9). Remove the inlay. Coat the inlay with the separating medium so that there is a complete cure of the composite resin inlay without an oxygen-inhibiting layer. Place the separator-coated inlay in the light-and-heat curing unit for the 7-minute curing cycle (5 minutes at lIOG C effects a greater than 90% cure) (Fig. 10). Rinse the cured inlay and preparation with waterspray and dry. Etch the tooth (enamel and glass ionomer) for 15 sec-

onds with 37% phosphoric acid,’ wash, and dry (Fig. II). 23. Etch the internal surface of the in!ay with 9.5% hydrofluoric acid (Ceram-Etch, Gresco Products; Stafford, Tex.) for 1 minute, wash og acid with water-air spray, and dry (Fig. 12). 24. Cement the finished composite resin inlay with Panavia EX (J. Morito, USA Inc., Tustin, Calif.) dental adhesive or similar chemically cured composite resin cement that is not tooth-colored, for easy identification of the excess cement. The preference for Panavia Ex material is that the cement has sufficient working time (3 minutes) so that it can be neatly applied to the inIay, the inlay inserted, and the excess cement removed before the cement sets. Cementation is as follows: (a) Shake the powder and place on No. 2 scoop on the mixing pad with two drops of liquid. (b) Mix for 90 seconds (minimurn), maintaining the mixed cement in a thin layer on the mixing pad. (c) Apply the mixed cement with a brush to the undersurface of the inlay in a thin uniform layer.

DIRECTCOMPOSITERESININLAY

(4 Insert the inlay and secure in place for 3 minutes. (e) Remove excesscement with a brush and Superfloss (Oral B Laboratories Inc., Redwood City, Calif.) dental floss while holding the inlay in place (Fig. 13).

(0 Apply Oxyguard (J. Morito, USA Inc.) material to the margins after the initial 3 minutes and sustain in place for 3 minutes, then rinse with a water/air spray (Fig. 14). 25. Remove the rubber dam and refine the occlusion (Fig. 15). SUMMARY The rationale and technique are presented for a direct composite resin inlay by using a light-heat curing unit to effect greater polymerization after initial curing with a conventional visible light-curing unit. Various composite resins and curing units are available, but this basic approach has broad application. The unique feature of this method is the Coltene D.I. Separator material that readily allows the removal of the cured direct inlay from the cavity preparation.

Bond durability structure

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dentinal

REFERENCES 1. Lambrechts M, Braem M, Vanherle G. Evaluation of clinical performance for posterior composite resins and dentin adhesives. Oper Dent 1987;12:53-78. 2. Davidson CL, deGee AJ. Relaxation of polymerization contraction stresses by flow in dental composites. J Dent Res 1984;63:146-8. 3. Jensen ME, Chan DCN. Polymerizationshrinkage andmicroleakage. In: Vanherle G, Smith D, eds. Posterior compositeresin dental restorative materials. Utrecht, The Netherlands: P Szulc Publishing, 1985;243-62. 4. Robinson PB, Moore BK, Schwartz ML. Comparison of microleakage in direct and indirect composite resin restorations in vitro. Oper Dent 1987;12:113-6. 5. Wendt SL. The effect of heat used as secondary cure upon the physical properties of three composite resins. II. wear, hardness, and color stability. Quintessence Int 1987;18:351-6. 6. Howard WW. Atlas of operative dentistry. 2nd ed. St. 1,ouis: CV Mosby co, 1973;17. 7. Barkmeier WW. Schaffer SE, Gwinnett A.J. Effects ol’ 15 vs 60 second enamel acid conditioning on adhesion and morphology Oper TIenr 1986;11:111-6. Reprint requests to. DR. JASON D. BIEDERMAN 34 GLEN COVE RD. GREENVALE, NY 11548

bonding

agents

E. L. Davis, Ph.D.,* R. B. Joynt, D.D.S.,** G. Wieczkowski, Jr., D.D.S.,*** J. C. Laura, D.D.S.**** State University of New York at Buffalo, School of Dental Medicine, Buffalo, N.Y.

and tooth

and

Glass-ionomer cements and dentinal bonding agents have made possible cavity preparations without mechanical retention. However, durability of bond strength is critical to the longevity of these restorations. This research evaluated the durability of the chemical bond formed by four materials attached directly to tooth structure. Tenure bonding agent recorded the strongest bond at each thermocycling time. In addition, whereas the bond strength remained unchanged for Scotchbond bonding agent, Ketac-Bond glass-ionomer cement, and GC lining cement, bond strength for Tenure bonding agent increased with thermocycling. (J PROSTHET DENT 1989;62:263-6.)

R estorations that strengthen weakened teeth could have a substantial impact on restorative dentistry. Initial studies of posterior composite resins used with acid-etch This research was supported in part by USPHS grant No. DE07106. *Assistant Professor,

Departments

of Operative

Dentistry

and

Behavioral Sciences. **Clinical

Assistant

Professor,

Department

of Operative

Den-

tistry. ***Associate Dentistry.

Professor

and Chairman,

Department

****Private practice. 10/l/12828

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techniques suggested that these materials strengthened remaining tooth structures. l, 2 However, later studies revealed that posterior composite resins do not increase resistance to cuspal fracture in clearly compromised teeth.“” Interest has focused recently on gla&ionomer cements (GE) and dentinal bonding agents as bases for posterior composite resin restorations because they bond chemically to tooth structure. GIC can also be acid-etched, providing a mechanical lock between the cement and a composite resin.6 Thus a restorative system with a GIC base in con-

junction with composite resin uses both chemical adhesion and a mechanical interlock to retain the restoration.

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