Class II Direct Composite Resin Restorations with Beta-Quartz Glass-Ceramic Inserts Robert E

Operative Dentistry

Class II direct composite resin restorations with beta-quartz glass-ceramic inserts Robert E. Rada*

With the increasing demand for esthetic posterior restorations, numerous ¡eclmiques have been developed. The direct resin restoration has probably been u.sed most exten- sively in Cla.ss II situations. Problems with Class II direct resin restorations include difficulty in developing proximal contact, occlusal wear, and polymerization shrinkage. Beta-quartz glass-ceramic inserts have been developed in an attempt to reduce the inci- dence of these potential problems. They can be placed in a one-appointment technique, are relatively inexpensive, and can readily be utilized by the clinician adept in placing Class II composite resin restorations. (Quintessence Int 1993:24:793-798.)

Introduction The most economical, estbetic technique is the direct composite resin restoration. These restorations in tbe past decade there bas been a tremendous in- are best suited for conservative Class I and Class II crease in the number of techniques available that may situations. The clinician may encounter numerous be used to conservatively and esthetically restore the complications when placing posterior resin restora- posterior dentition. These techniques have varied tions, including difficulty in achieving proximal con- from those that allow direct placement of tbe restor- tact, occlusa! wear, and polymerization shrinkage, ative material, to those that require indirect, labora- which in turn can cause microleakage and postoper- tory fabrication, to those that incorporate a combi- ative sensitivity.-••' nation of direct and indirect procedures. Both com- Porcelain inlays and onlays have been utilized to posite resin and dental porcelain are presently being enhance operator control of tbe posterior estbetic res- utihzed. torations. Posterior ceramic restorations are fabri- These esthetic restorations are typically conserva- cated in the dental laboratory. This indirect fabrica- tive, ¡eave sufficient tooth structure remaining for tion allows the ceramist to create optimal tooth con- proper retention and resistance forms, and require tours and proximal contacts. Only a thin layer of com- minimal tooth preparation. If significant tooth struc- posite resin is used; as a result, polymerization shrink- ture has been lost or if the patient is incapable of age is minimized. Porcelain restorations have several meticulous maintenance of tbe oral tissues, more con- disadvantages. These restorations are fragile and very ventional restorations are indicated. All of the pres- prone to breakage during try-in and bonding as well ently available conservative, esthetic restorative op- as during beavy occlusal stresses. They require mul- tions are highly technique sensitive.' tiple appointments because of laboratory fabrication and as a result a provisional restoration is necessary. Additionally, fees must be significantly higher than those for directly placed composite resin restorations."" Composite resin has also been used in both an in- ' Prívale Practice, 1415 West 47'" Street, La Grange, IHinOLS 60525; direct technique and a direct-indirect tecbnique. Tbe Formerly Assistant Professor, Division of Operative Dentistry, Department of Restorative and Preventive Dentistry, Loyola indirect tecbnique offers many of the same advantages University. and disadvantages of the porcelain restoration.-^ The

Quintessence Internationai Volume 24, Number 11/1993 793 operative Dentistry

Fig 1 A Class II preparation in the mandibular first molar is tobe restored with composite resin-glass-eeramic insert restoration. Clear matrices and wedges are used. The puip- al floor is lined with glass-ionomer iiner.

Fig 2 (right) The giass inserts are availabie in three shapes, each in three different sizes.

direct-indirect composite resin restoration is intended Technique to maximize the benefits of curing the resin outside the oral cavity, thus reducing polymerization shrink- Many of the procedures utilized in placement of direct age in the bulk of the restoration. It allows fabrication posterior composite resin restorations are employed in a single, albeit lengthy, appointment. However, it when ceramic inserts are used. Cavity preparation is is extremely difficult to perform and requires the op- identical. Conservatism is maximized, internal line an- erator to have special equipment (a Hght- and heat- gles are rounded, and occlusal cavosurface margins euring oven).* are not beveled. Pulpal protection can generally be The ideal posterior esthetie restoration remains one accomplisbed by use of glass-ionomer lining mate- that ean be placed directly, in one appointment, ex- rials: a calcium hydroxide liner is placed first in es- hibits good tooth eontours, has long-term wear char- pecially deep areas of the preparation. Prewedging aeteristics, and minimizes polymerization shrinkage. during the preparation stage is frequently utilized to In an attempt to accomplish these goais. Lee Phar- ensure slight separation of the teeth and improve the maceuticals has introduced beta-quartz glass-ceramic restored proximal eontact. Rubber dam isolation dur- inserts for direct composite resin restorations. ing all phases of placement of the restorative materials These ceramie inserts are intended as megafillers to is absolutely essential to the success of these resto- reduce polymerization shrinkage of the restoration rations. Enamel etching, dentinal bonding agents, and and thus to reduce microleakage and postoperative unfdled resin are employed in the same manner as for sensitivity. They also help to minimize wear of the conventional posterior resin restorations. The prep- restoration and can aid in developing proximal con- aration is matrixed and wedged. The clear plastic tour and contact. The inserts are silane treated to matrices arc useful in visualizing placement of the improve bonding to composite resin and are fabri- inserts (Fig 1). cated in a variety of shapes and sizes. They have been At this point, the ceramic inserts are selected recommended for use in Class I, Class 11, and Class (Fig 2). Generally, one insert is selected for the prox- III cavity preparations.' The technique for placing a imal box area and one for the occlusal preparation. Class II composite resin-beta-quartz glass-ceramic The author has found the tapered cylinders to con- restoration is illustrated. form best to the proximal box and has used round

794 Quintessence international Volume 24, Number 11/1993 Operative Dentistry

Fig 3 A tapered cylinder insert is tried in the proximai box Fig 4 Alternatively, an L-shaped insert may be used in the and a round oyiinder is tried in the occlusal preparation. proximal box.

Fig 5 Composite resin is piaced around the glass insert Fig 6 Composite resin is placed in the occlusal portion of within the proximal box. The glass insert appositions the the preparation. proximal tooth surfaoe.

cylinders for the occlusal preparation (Fig 3). An L- floor of the preparation and laterally against the prox- shaped insert that may also be used in the proximal imal tooth surface. This will aid in the formation of hox is available (Fig 4). Whatever the shape desired a sohd proximal contact (Fig 5). Buccal and lingual for the cavity preparation, the largest insert should be increments of composite resin may then be placed, ehosen. This will maximize displacement of the com- forming the rest of the proximal tooth surface. The posite resin. The inserts are then coated with unfilled occiusal surface may be restored similarly through resin to assist in wetting the surface with composite insert placement in 1 to 2 mm of composite resin resin.* followed by incremental placement and curing of ad- The following technique for minimizing polymeri- ditional material (Fig 6). The curing light should be zation shrinkage and the resulting microleakage and directed at both the occiusal and proximal surfaces postoperative sensitivity, has been described. The ce- (Fig 7). ramic insert is placed into approximately 1 to 2 mm When placement and curing are completed, the ma- of unpolymerized composite resin at the gingival floor trix is removed and the handle of the insert is cut off of the proximal box. The posterior resin is photopo- with a medium-grit diamond bur used with water iymerized while the insert is held against the gingival spray {Figs 8 and 9).

Quintessence International Volume 24, Number 11/1993 795 Operative Dentistry

1 Fig 7 Photopolymerization is carried out in much the Fig 8 Giass insert materiai that rises above the surface of same manner as for conventional Class li composite resin the restoration is removed and contoured. restorations.

Fig 9 The handie of the insert is removed with high-speed Fig 10 The inserts are finished first with abrasive points. diamonds and wafer spray. The restoration is contoured simultaneousiy.

Fig 11 Finai poiish is accomplished with diamond and alu- Fig 12 The final restoration is coated with a surface-pen- minum oxide poiishing pastes. etrating sealant

796 Quintessence International Volume 24, Number 11/1993 Operative Dentistry

Finishing of the restoration will vary slightly when the ceramic inserts are used. The restoration is made up of two distinct surfaces, ceramic and composite resin. Ultrafine diamonds or multifluted carhide btirs should be used to define the occiusal anatomy and proximal tooth contours, Pohshing should be directed first toward the ceramic portion of the restoration. Ceramic polishing points and diamond polishing paste may be used (Fig 10), The composite resin is then polished with conventional abrasive points, disks, and pastes (Fig 11), The restoration should be coated with a surface- penetratiug sealant. This material (Fortify, Bisco Fig 13 The completed restoration demonstrates esthetics, Dental) penetrates microstructural defects, reducing occiusal morphology, and acceptable proximal contact. long-term wear of the composite resin, and ehminates marginal defects^'" {Fig 12). The final restoration is both structurally sound and of sufficient esthetic qual- ity (Fig 13).

torations can easily adapt to this new treatment mo- da h ty. Discussion Directly placed posterior Class II resin restorations Summary may fail because of occiusal wear, postoperative tooth sensitivity, marginal leakage, and restoration fracture. A technique for placernent of Class II posterior com- Additionally, proximal contour and contact can be posite resin restorations with beta-quartz glass-ceram- diificult to develop. Indirect posterior esthetic resto- ic inserts has heen presented. These inserts improve rations are time consuming and costly to fabricate. restoration strength, reduce polymerization shrinkage Beta-quartz glass-ceramic inserts are one attempt at and microleakage. allow formation of good próxima! maximizing the direct posterior resin technique. contours and contact, and can be placed in a reason- Glass inserts were developed at the American Den- ably short time period at a low cost. Long-term chn- tal Association Health Foundation. Paffenharger Re- ical studies will be necessary to determine if these es- search Center, of the National Institute of Standards thetic restorations will truly be effective in improving and Technology. They are composed of a lithiumalu- the life expectancy of directly placed composite resin minosilicate glass that undergoes various heat treat- restorations. tnents and is silauated to enhance chemical bonding of the insert to composite resin. Beta-quartz glass- ceramic inserts minimize marginal contraction gaps and microleakage in composite resins. They have a sevenfold lower coefficient of thermal expansion than References amalgam. Polymerization shrinkage is reduced by 1. Truskowsky RD Comparison of aesthetic posterior restora- 50% to 75%. Proper use of the inserts can improve tions. Pract Periodont Ae«het Dent l991;3(6):33-39. proximal eontact in direct posterior esthetic resin res- 2. Eich JD. Weich PH. Polymerization shrinkage or posterior torations. They have been shown to reduce wear in composite resins and its possible inflnence on postoperative contact areas. The ceramic inserts match adjacent sensitivity. Quintessence Inl 19S6:17:103-l II. tooth structure and composite resin shades and are 3. Leinfelder KF Using composite resin as a posterior restorative material. S Am Dent Assoc 1991:122:65-70. hiocompatible and radiopaque."""'' 4. Calamia JR. High strength porcelain bonded restorations: An- Minimum additional placement and finishing time terior and posterior. Quintessence Int 19S9;20:717 726. 5. Jackson RD, Ferguson RW. An esthetic bonded inlay/onlay is necessary, and each insert is relatively inexpensive technique for posterior teeth. Quintessence Int 1990;21:7-12, (approximately US$ 2 each). Any clinician comfort- 6. Candido SJ. The direct resin inlay: Clinical protocol. Compend ahie with placing direct posterior composite resin res- Contin Educ Dent ¡9KK;9:292-301.

Quintessence International Volume 24, Number 11/1993 797 operative Dentistry

7. Bowen RL, Eichmiller FC, MatjenholT WA. Glass ceramic to. Dickinson GL, Leinfclder K.F, Mazer RB, Russell GM. Effecl inserts anticipated for mcgafilled composite restorations. J Am of surface penetrating sealant on wear rate of posterior com- Dent Assoc 1991:122:71-75. posite resins. J Am Dent Assoe 1990,121:251-255. 8. Bowen RL, Setz L, Eichmiller, et al. Bêla Quartz Glass Ce- 11. Bowen RL. Reduction or microleakage around composite res- ramic Insert. South El Miinte, CA, Lee Pharmaceuticals, toralLOns [abstract 1117]. J Dent Res t987;66:246. 12. Bowen RL, Setz LE. Posterior composite resins with a novel 9. Donly K.J, Witd TW, Bowen RL, Jensen ME. An in vitro structure [abstract 642]. J Dent Res 1985;65:797. investigation of the effects of glass inserts on the effective composite resin polymerization shrinkage. J Dent Res 13. Donly KJ. Ellis RK. Glass inserts. A new dimension in res- t989;68:l 234-1237. torative dentistry. Am J Denl 1989:2:21-24. D

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798 Quintessence International Voiume 24, Number 11/1993