Acquired Tooth Damage

Acquired tooth damage, discussed in Chapter 14, is one of the main reasons for restorative therapy.

Defective Restorations

Defective restorations no longer restore the dentition to an acceptable state of form and function. Although restorations can be either temporary or permanent, no restoration can be considered truly permanent. Physical properties of restorative materials make them susceptible to alteration and deterioration. Certain materials, however, have withstood the test of time and are more readily recognized for their longevity. When properly used, gold restorations are the most durable and compatible in the oral environment. Their resistance to corrosion, nonirritating chemistry, and similarity to enamel in texture and wear resistance are qualities that other materials often lack. Amalgam is the most commonly used restorative material in dentistry because of its versatility, workability, and clinical longevity. However, masticatory forces and tooth-to-tooth contact eventually wear the occlusal margins of most amalgam restorations (Figure 36-1). Tooth-colored resin composite restorations shrink slightly during the curing process and require careful technique to obtain the desired long-lasting results. Cement materials dissolve in the oral environment, resulting in the loosening of luted restorations.

Figure 36-1 Large amalgam restoration, which has served for many years despite its poor design, exhibits defective margins.

Defective restorations, however, may not always be related to the restorative material. Defectiveness of restorations also can be caused by the placement techniques of the clinician; for example, overhangs, open margins, poor contours, and open proximal contacts are the result of improper technique, poor judgment, and lack of attention to detail (Figures 36-2 and 36-3). These are avoidable defects and are not acceptable standards of care.

Figure 36-2 This radiograph shows poor proximal contour and a gingival overhang on the distal surface of the maxillary first molar. The maxillary second premolar exhibits amalgam fractures and dislodgement.

Figure 36-3 Note possible defects at the gingival margins of restorations. It may be possible to remove an overhang without replacing the restoration; however, restorations with short and open margins require replacement.

Esthetic Appearance

Restorative therapy is also an important factor in meeting a person’s need for a wholesome facial image. Missing, broken, or obviously decayed teeth are often the reasons individuals seek oral healthcare. Dental anomalies such as diastemas, mottled enamel, congenital tooth defects, and intrinsic tooth discolorations such as tetracycline staining also may require restorative interventions to improve appearance. One of the main disadvantages of metallic restorations has been esthetics (Figure 36-4). To maintain the esthetic appearance of restorative materials, special polishing paste is used (e.g., Soft Shine [Water Pik, Inc, Fort Collins, Colorado]).

Figure 36-4 Tooth darkening resulting from the display of amalgam and associated internal staining.

Occlusion

The occlusal relationship influences the function and health of the dentition. Restorative treatment can be provided to improve a person’s occlusion. There are times when an occlusal adjustment, the selective reshaping of the dentition by grinding, can improve the occlusion. This is especially true when previous restorations have been poorly contoured. When teeth become misaligned because of the loss of adjacent or opposing teeth, it may be necessary to recontour them to establish a stable, functional occlusion by realigning the vector of occlusal forces to be more parallel to the long axis of the teeth (Figure 36-5). Complex restorations are necessary if this recontouring results in substantial tooth crown removal. Complete coronal restorations (crowns) and even fixed partial dentures (bridges) are necessary to restore occlusion in badly damaged dentitions.

Figure 36-5 Tooth loss has resulted in pathologic occlusion from tooth movement (tip, drift, and extrusion).

Mastication

The most basic function of teeth is to chew food and thus begin the process of digestion. A significant number of clients indicate inadequate chewing as their chief complaint. Often frustration exists because certain favorite foods are difficult to chew. Therefore a missing tooth, defective restoration, or carious lesion can compromise an individual’s eating pleasure and nutrition.

Types of Restorations

Direct Restorations

Restorations are categorized by the technique required for placement of the restorative material. These placement techniques have been classified as direct and indirect. Direct restorations are placed and formed directly in the cavity preparation. These restorations are typically placed in increments, adapted closely to the cavity walls, and shaped to the desired contours. Shaping is done with carvers when the materials are still in a soft or an unset state and with rotating instruments such as burrs and disks, used when the restorative materials are in a hard or set state. Materials used in direct restorations include moldable substances such as amalgam, resin-based composite, resin-modified glass ionomer, and direct gold. In addition, preformed stainless steel crowns that are adapted to prepared teeth using trimming techniques and crimping pliers are considered direct restorations. The restorative procedures that have been legally delegated to REF dental hygienists fall within the direct restoration category. Table 36-1 outlines the uses, advantages, and disadvantages of direct restorative materials.

TABLE 36-1 Direct Restorations

Indirect Restorations

Most indirect restorations are formed on reproductions (dies) of prepared teeth. The shaping of the restoration is done by preparing the desired form in wax and then casting this form in metal or ceramic. Porcelain restorations are formed by building the restoration to shape with porcelain powder and then solidifying the mass in a special “firing” oven. Gold crowns or inlays and porcelain crowns are typical indirect restorations. Because indirect restorations are rigid, solid objects, the cavity preparation must be specially designed (tapered) to allow complete seating of the restoration at the time of permanent cementation. Computer-aided design and computer-aided manufacture (CAD-CAM) restorations are prepared chairside using a computer. With a small intraoral camera the dentist makes a digital picture of the tooth before and after preparing it. This digital image contains three-dimensional information about the size of the tooth, the defect being restored, and the adjacent teeth. The dentist then designs the desired crown or filling directly on a computer screen using CAD-CAM software. Once all the pertinent information has been entered, a tooth-colored block of ceramic material is machined by the computer.¹

Table 36-2 outlines the uses, advantages, and disadvantages of indirect restorative materials.

TABLE 36-2 Indirect Restorations

Cavity Preparation

Black’s Classification System and the Complexity Classification System, presented in Chapter 14, are used to describe the type and location of dental caries and dental restorations. These systems expedite communication among those involved in the delivery of dental services.

A critical step in restoring the dentition is the preparation of the cavity. The intent of this section is to present the fundamentals of cavity preparation essential to each member of the oral health team. A basic understanding of the principles and instrumentation of cavity preparation supports the dental hygienist as a collaborative member of the team.

Atraumatic Restorative Treatment

Atraumatic restorative treatment (ART) is “a dental caries treatment procedure involving removal of soft demineralized tooth tissue using hand instruments alone, followed by restoration of the tooth with an adhesive restorative material, routinely glass ionomer.”² ART is typically used for persons who are young, are uncooperative, or have special healthcare needs and provides caries treatment at a low cost. ART requires no anesthesia or power-driven equipment. Developed in Tanzania in the mid-1980s, it is used successfully in developing countries, where carious teeth often go untreated. In these countries, nondental personnel or primary healthcare workers provide ART; it is endorsed by the World Health Organization and the International Association for Dental Research.³ The American Academy of Pediatric Dentistry (AAPD) policy statement on interim restorative therapy (IRT) states, “The AAPD recognizes IRT as a beneficial provisional technique in contemporary pediatric restorative dentistry. IRT may be used to restore and prevent dental caries in young patients, uncooperative patients, patients with special health care needs, and situations in which traditional cavity preparation and/or placement of traditional dental restorations are not feasible.” IRT may be used for caries control in children with multiple carious lesions prior to definitive restoration of the teeth.2 IRT uses similar techniques as ART but has different therapeutic goals in that an IRT is not a definitive restoration. ART/IRT may be used to increase access to dental care by reducing costs. Currently it is not included in the scope of practice for restorative function dental hygienists in the United States.

Delivery of Restorative Therapies and the Dental Hygienist

Originally the dental hygienist was chiefly responsible for the prevention of oral disease, which explains why today the dental hygienist is recognized as an oral disease preventive and health promotion specialist. However, in the 1960s and 1970s it was theorized that the dental hygienist could play a significant role through the delivery of restorative therapies. It was at this time that the primary focus of the dental profession became improving the oral health of the public through the elimination and treatment of dental caries. Therefore the rationale for the initial delegation of restorative services was to provide a mechanism to respond to an expanding need and demand for dental care, making dental hygienists responsible for expanded functions. These programs were eliminated due to pressure from organized dentistry.

Because the scope of dental hygiene practice varies dramatically among states, provinces, and territories, not all educational programs prepare dental hygienists to practice in all locations.⁴ The dental hygienist has the legal and ethical responsibility to practice within the scope of the law at all times.

Rationale

The purpose of the rubber dam is to improve the quality of restorative dental treatment via the following:

Moisture control

Accessibility and visibility

Client and operator protection

Disadvantages

The disadvantages of the rubber dam most often cited are time consumption and client objection. The efficient practitioner overcomes the perception of the procedure as time-consuming. The quality of restorations completed with the rubber dam should outweigh perceived inconvenience. Client objections can usually be overcome with education.

Contraindications

Rubber dam application may be contraindicated because of cracks or fissures of the commissures, herpetic lesions, respiratory congestion, claustrophobia, asthma, and latex allergy.

Rubber Dam Material

Features considered in the selection of rubber dam material are as follows:

Size (in inches)

Weight

Color

Latex versus nonlatex

The rubber dam material is typically marketed as a 5- × 5-inch child size or a 6- × 6-inch adult size latex sheet. Weights of rubber dam material are light, medium, heavy, extra heavy, and special heavy. The lighter weight, thinner dams are easier to apply because of flexibility and client comfort, whereas the heavier weight, thicker dams provide better retraction of tissues and protection from revolving instruments. Medium and heavy weights are most commonly used for restorative procedures. Rubber dam material is available in black, gray, white, green, blue, and pastels. Although color selection is based on operator preference, the main issues to consider in color selection are the contrast with the teeth and eye. Many of these materials now are pleasantly scented. Nonlatex rubber dam materials are available for clients allergic to latex.⁵

Rubber Dam Punch

The rubber dam punch, used to punch the tooth holes in the rubber dam material (Figure 36-7), typically has five or six hole sizes.

Figure 36-7 Rubber dam punch.

Rubber Dam Forceps

Rubber dam forceps, plierlike forceps that expand the rubber dam retainer for placement on the tooth, are used to place the rubber dam retainer (clamp) on the anchor tooth (Figure 36-8). The beaks of the forceps are placed into the holes of the retainer, and when the handles of the forceps are squeezed, the beaks are separated and the retainer is expanded. The rubber dam forceps have a locking device that may be engaged, allowing release at the handles without loss of the desired expansion.

Figure 36-8 Rubber dam forceps.

Rubber Dam Frame

The rubber dam frame is used to secure the extraoral rubber dam material during the procedure (Figure 36-9). Several styles of frames satisfy operator preference; however, the frame must be sterilizable or disposable. The most commonly used rubber dam frame is a U-shaped stainless steel frame with small projections for securing the edges of the rubber dam sheet.

Figure 36-9 The rubber dam frame is used to secure the edges of the rubber dam.

Rubber Dam Retainer

The rubber dam retainer provides intraoral stabilization of the rubber dam material by anchoring the material securely in place. The rubber dam retainer is produced in winged and wingless designs. The parts of the rubber dam retainer include the jaws, prongs, bow, and forceps holes, as follows (Figure 36-10):

The prongs contact the clamped tooth.

The bow joins the two retainer jaws.

The forceps holes are the insertion point for the rubber dam forceps during the placement and removal of the retainer.

Figure 36-10 Rubber dam retainer design and parts.

Retainer designs are identified by number. Winged and wingless retainers of the same number are identical in shape; however, the letter W is used to designate the wingless retainer. The wings of a retainer provide additional retraction of the rubber dam material away from the retainer tooth. Retainers come in numerous shapes and sizes to take into consideration the specific tooth to be retained (permanent or primary), the stage of eruption of the tooth to be retained, and the access needed for the operation (Figure 36-11). Success of rubber dam isolation depends largely on the stability of the rubber dam retainer.

Figure 36-11 Rubber dam retainer variations: wingless molar retainers (upper left and right), winged premolar retainer (lower right), winged molar retainer (lower left), and anterior retainer (center).

Retainer Selection

Selection of the rubber dam retainer is the next step in rubber dam application. The anchor tooth is the tooth to be retained and the most distal tooth to be isolated. Four points of consideration when selecting the retainer for the anchor tooth are as follows:

Mesiodistal width between the prongs of the retainer jaws should be slightly narrower than the mesiodistal width of the anchor tooth at the cementoenamel junction (CEJ).

Mesiodistal curvature of the retainer jaws must be greater than the mesiodistal curvature of the anchor tooth at the CEJ.

Faciolingual width between the prongs of the retainer jaws should be narrower than the faciolingual width of the anchor tooth at the CEJ.

Bow of the retainer must arch high enough to clear the occlusal surface of the anchor tooth when the retainer is appropriately seated.

Each of these criteria (illustrated in Figure 36-12) permits the correct and stable seating of the jaw prongs on the anchor tooth. Usually in the anterior aspects of the arches, the rubber dam can be successfully retained without the use of a retainer. Small pieces of rubber dam, or other devices such as wooden wedges and/or floss, can be inserted between teeth to hold the dam in position.

Figure 36-12 Retainer selection criteria: mesiodistal width of the retainer (1); mesiodistal curvature of the retainer (2); faciolingual width of the retainer (3); and height of the retainer (4).

Rubber Dam Material Preparation

Several techniques are used to determine hole placement on the rubber dam. A rubber stamp or cardboard template can be used as a guide for marking the placement of holes for primary and permanent dentition (i.e., marks correspond to the teeth to be punched) (Figure 36-13). As the operator becomes proficient, the template is no longer needed. The tooth to receive the retainer may require a double or triple hole. The holes must be punched precisely without tags and tears, which facilitate further tearing when the dam is stretched over the tooth (Figure 36-14). For clean holes to be punched, the rubber dam punch must be well maintained and free of lodged rubber dam material. In addition, the action of punching the dam must be sharp and determined, not uncertain and hesitant.

Figure 36-13 Stamp used with inkpad on rubber dam sheet marks template to punch holes for permanent and primary dentition.

(From Bird DL, Robinson DS: Torres and Ehrlich modern dental assisting, ed 9, St Louis, 2009, Saunders.)

Figure 36-14 As pictured left to right, triple hole, double hole, tag, and tear.

When the dentition is normally spaced and aligned, 3 to 4 mm should be left between holes. Holes punched too close together cause stretching and inadequate seal around the tooth, whereas holes punched too far apart result in excess material and bunching (Figure 36-15).

Figure 36-15 Rubber dam problems: dam not through proximal contact between teeth 20 and 21; bunching of the dam between teeth 19 and 20; and stretching of the dam, exposing the gingiva between teeth 18 and 19.

Rubber Dam Placement Technique

Two techniques for placement of retainer and rubber dam material are as follows:

The two-step process of placing the retainer and then the rubber dam material (Figure 36-16)

The placement of retainer and rubber dam material in a single step, which requires that the rubber dam material be placed over the bow of the retainer and then carried into its ultimate location (Figure 36-17)

Figure 36-16 The retainer is positioned with rubber dam forceps.

Figure 36-17 In a single step, the retainer is seated and the rubber dam carried in.

Selection of a technique is best left to operator preference. The remaining steps are identical for both techniques. The hole is then stretched to the lingual side and spread over the lingual jaw; the procedure is repeated for the facial side. The anchor tooth is now the only tooth isolated in the rubber dam (Figure 36-18). A piece of dental floss is tied to the jaw of the retainer to facilitate retrieval should the retainer break or be dislodged (Procedures 36-1 and 36-2).

Figure 36-18 The rubber dam hole is stretched to enclose and isolate the retainer and anchor tooth.

Figure 36-19 Retainer ligation progressing from lingual (left) to facial (right), and a broken ligated retainer at far right.

Figure 36-20 Dental floss is used to carry the septa between the teeth using the double flossing technique.

Figure 36-21 The spoon excavator is supported by an air stream to invert the dam and create a seal.

Figure 36-22 A well-sealed, properly inverted rubber dam.

Figure 36-23 The retainer is removed from the tooth with forceps.

Figure 36-24 Rubber dam is stretched, and septa are cut with scissors.

Figure 36-25 Tooth lost to undetected band of rubber dam left after dental treatment.

Amalgam

Dental amalgam remains the standard restorative material for posterior teeth; this reputation is based on decades of clinical evaluation during which it has proven to be a durable material even when placed in some compromised circumstances.⁴ Its longevity is directly related to proper cavity preparation, attention to basic principles of manipulation, and condensation in a moisture-free environment.

Armamentarium

The following equipment is needed for placement of an amalgam restoration.

Triturator (Amalgamator)

The triturator is a mechanical device used to mix the encapsulated alloy and mercury (Figure 36-26). It is adjustable for speed and time of trituration to achieve the correct amalgam mix.

Figure 36-26 Amalgam capsule is placed in the triturator. Mixing time is set according to manufacturer’s instructions.

(From Bird DL, Robinson DS: Torres and Ehrlich modern dental assisting, ed 9, St Louis, 2009, Saunders.)

Amalgam Well

The amalgam well is a small, heavy, stainless steel dish with a cuplike recess that confines the mixed amalgam to facilitate pickup with the amalgam carrier (Figure 36-27); mixed amalgam is transferred immediately from the amalgam capsule to the amalgam well after trituration.

Figure 36-27 Amalgam well and carrier.

Amalgam Carrier

The instrument used to carry and dispense amalgam into the cavity preparation is the amalgam carrier (see Figure 36-27). The operator loads amalgam into the barrel (cylinder) by pressing the barrel tip into the amalgam mass contained in the amalgam well. When pushed, the instrument lever forces a plunger to dislodge the contained restorative material from the barrel.

Condensing Instruments

Condensing instruments are used to pack amalgam and other restorative materials firmly into a cavity preparation. There are numerous shapes and sizes of condensers (Figure 36-28). Selection is based on size and configuration of the cavity preparation and amount of material to be condensed.

Figure 36-28 Large and small amalgam condensers.

Carving and Burnishing Instruments

Carving and burnishing instruments are used to remove excess restorative material and refine the margins of the restoration. All carvers are sharp, cutting instruments. Numerous blade shapes and sizes are selected for use based on carving action to be completed and personal preference (Figure 36-29). Burnishing instruments are ball-, egg-, or beavertail-shaped instruments that give a smooth surface to the setting amalgam (Figure 36-30).

Figure 36-29 Common amalgam carvers. As pictured left to right, cleoid, discoid, 1/2 Hollenback, and Baum interproximal carver.

Figure 36-30 Burnishing instruments.

From Boyd LB:Dental instruments: a pocket guide, ed 3, St Louis, 2009, Saunders).

Tofflemire Matrix System

The Tofflemire matrix system is a device that reproduces proximal wall(s) removed during the preparation of the tooth. Numerous matrix techniques are available, but by far the most popular and versatile for amalgams is the Tofflemire matrix system. This system is composed of a Tofflemire retainer,matrix bands, and wedges (Figure 36-31). The Tofflemire retainer is a stainless steel mechanical device used to hold thethe matrix band. After preparation of a Class II or IV cavity prep, the matrix does the following:

Confines the restorative material during insertion, thereby allowing adequate condensation pressure

Provides a framework for reconstruction and contouring of missing tooth anatomy

Supports establishment of proper proximal contacts

Prevents overhangs

Figure 36-31 Tofflemire retainers and bands. As pictured top to bottom, straight retainer, and modified bands that fit either retainer.

Figure 36-32 The ends of the band are placed evenly together to form a loop. The loop is tapered to permit adaptation at the gingival aspect.

Figure 36-33 Diagram of the Tofflemire retainer.

Figure 36-34 Initial placement of band in retainer slot with occlusal aspect of loop being inserted first.

Figure 36-35 The locking nut is tightened to secure the band in the retainer.

Figure 36-36 Inserted band before shaping (bottom) and band shaped to rounded form to facilitate placement (top).

Figure 36-37 Initial placement of band over prepared tooth. Finger pressure supports lingual aspect of band.

Figure 36-38 Wedge is inserted into lingual embrasure between band and adjacent tooth using cotton forceps.

Figure 36-39 The handle of the cotton forceps is used to firmly position the wedge.

Figure 36-40 The band is firmly burnished against the adjacent tooth.

Figure 36-41 Final preparation and matrix system.

Wedges

Wedges are typically triangular (in cross-section) pieces of wood or plastic that come in numerous sizes and adaptations. They are usually placed from the lingual side because the lingual embrasure is larger than the facial embrasure, thereby allowing a more complete wedge placement (Procedure 36-3). A properly shaped and positioned wedge does the following:

Gently displaces rubber dam and gingival papilla in an apical direction

Supports the matrix band in the proximal space without encroaching on the contact area

Adapts the band to the gingival cavity margin

Provides slight tooth separation that supports the attainment of a positive proximal contact after removal of the matrix band

Procedure 36-3 PLACING A TOFFLEMIRE MATRIX SYSTEM

EQUIPMENT

Personal protective equipment

Protective eyewear for client

Tofflemire retainer

Matrix bands

Wooden wedges

Metal-cutting scissors

Cotton forceps

Modeling compound

Burnishing instrument

Tofflemire matrix system

STEPS

1. Evaluate the prepared tooth.

2. Select a matrix band that best encloses all lateral aspects of the cavity and extends 1 to 2 mm above the adjacent marginal ridge and 1 mm beyond the gingival margin.

3. Select a matrix retainer.

4. Loop band in fingers so that ends match. The convergent opening (smaller) of the loop should be positioned next to the gingiva (rubber dam) (Figure 36-32).

5. Position locking vise approximately ¼ inch from end of retainer and free locking screw (spindle) from band slot in the locking vise (Figure 36-33).

6. Position loop in retainer (leading with the occlusal edge of the band); insert matched ends into the slots in the locking vise and the loop into the appropriate guide channel.

When positioned, the guide channels of the retainer open toward the gingiva.

The loop of band should exit guide channel to allow the loop to be positioned from the preferred side of the tooth (usually the facial side).

Assuming that the seated retainer will be most commonly positioned on the facial aspect of the prepared tooth, use left channel guide for dentition in the maxillary left and mandibular right; use right channel guide for dentition in the maxillary right and mandibular left.

When inserting band into the retainer, first insert the wider occlusal aspect of the band so that the retainer is seated with the slots of the retainer toward the gingiva (Figure 36-34).

7. Secure matrix band by advancing the locking screw (smaller nut) (Figure 36-35).

8. Shape matrix loop into a rounded form: (1) insert an instrument handle through the loop, (2) pinch the band between the instrument handle and your thumb, and (3) rotate your wrist as you pinch the band (Figure 36-36).

9. Position loop around tooth with slots of the Tofflemire and narrow aspect of band toward the gingiva (Figure 36-37); brace lingual aspect of loop with thumb of opposite hand; gently tighten band by rotating the adjusting nut (larger nut).

Examine placement of band to ensure that band extends occlusally 1 to 2 mm beyond the adjacent marginal ridge; it should also extend apically approximately 1 mm beyond the gingival margin without impinging on soft tissue.

10. Moisten wedge(s) and place into the lingual embrasure between band and adjacent tooth, slightly beyond the gingival margin (Figure 36-38). Apply steady pressure on base of the wedge to move it in a facial direction to desired position (Figure 36-39). Numerous pretrimmed wedges are available for selection.

11. Burnish internal aspect of band against the adjacent tooth (or teeth) with a thin, rigid instrument (Figure 36-40).

12. Conduct a final evaluation of cavity preparation with matrix system in place (Figure 36-41).

Trituration

Modern amalgam materials are pre-encapsulated to prevent mercury spills and provide consistent quality of mixes (Figure 36-42). Capsules contain small and large quantities for selection according to the cavity size. Within each capsule, a plastic diaphragm separates the mercury from the alloy. At the start of trituration the diaphragm ruptures, allowing amalgamation (trituration) to begin. Thorough mixing occurs within a few seconds, according to the metallurgy of the mass and the speed of the amalgamator. The operator determines the proper setting of the instrument based on the manufacturer’s recommendation, the amalgam material, and the desired mix. Following amalgamation, the mass is transferred to the amalgam well. Generally a proper mix of amalgam is shiny, homogeneous, and easily manipulated with the amalgam carrier and condensers (Figure 36-43).

Figure 36-42 Common pre-encapsulated amalgam capsule.

(From Bird DL, Robinson DS: Torres and Ehrlich modern dental assisting, ed 9, St Louis, 2009, Saunders).

Figure 36-43 Soft, shiny proper amalgam mix (left) and dry, crumbly overtriturated mix (right).

Figure 36-44 A small increment of amalgam is expressed into the proximal box of the cavity preparation.

Figure 36-45 Initial condensation is begun with a small condenser in the proximal box.

Figure 36-46 Additional increments of amalgam are carried to the cavity preparation.

Figure 36-47 The cavity is overfilled with amalgam, and a large condenser is used to complete condensation.

Figure 36-48 Burnishing of the overpacked amalgam.

Figure 36-49 Marginal ridge height and outer contours are established with an explorer.

Figure 36-50 Excess amalgam is removed with a carver.

Figure 36-51 Occlusal margins are recovered.

Figure 36-52 The wedge has been removed, and the retainer loosened from the band.

Figure 36-53 An amalgam condenser is used to stabilize the marginal ridge during the removal of the band.

Figure 36-54 Gingival margin is checked for excess amalgam with an explorer.

Figure 36-55 Excess amalgam at the gingival margin is carved away.

Figure 36-56 Amalgam anatomy should be carved to shallow form whenever possible. Doing so produces stronger margins (A). Thin angles seen in B will eventually fracture from occlusal stress.

Figure 36-57 The occlusal markings show that the contact on amalgam, although present, is lighter than that on the natural tooth. As a result the operator does not need to further reduce the occlusal contact.

Figure 36-58 Using a stroke parallel to the margin, a sharp carver refines occlusal margins of the amalgam.

Figure 36-59 A rubber polishing cup is used to polish the marginal ridge and cusp slopes. An air stream is used as a coolant.

Figure 36-60 A rubber polishing point is used to polish pits and grooves.

Figure 36-61 A polished amalgam.

Condensing, Carving, and Burnishing Amalgam

Condensation is the process of packing the amalgam into the prepared cavity. Adequate pressure is approximately 8 lb/inch² for lathe-cut alloys and slightly less for spheric alloys. Carving and burnishing is the process of using hand instruments to shape the freshly placed amalgam into the anatomic form that will restore tooth function (Procedure 36-4).

Finishing and Polishing

Polished amalgam retains less oral biofilm and resists tarnish and corrosion better than unpolished amalgam. After time the amalgam hardens fully and can be polished to a high degree of smoothness; amalgam restorations must be allowed to set up for at least 24 hours prior to rotary finishing or polishing. Obtaining a smooth surface is more important than achieving a high gloss on the metallic surface; gloss is usually short-lived because of the scouring action of certain foods.

It is imperative in the polishing procedures that undue heat is not generated from rotating rubber cups and points as they contact the amalgam. Such heat can harm the pulp, leaving the tooth very sensitive. The metallurgy of the amalgam also can be adversely affected. A wet field should be maintained whenever heat generation is a possibility.

Finishing and polishing procedures vary in materials and technique. However, the first step in the procedure is to recheck the occlusion to ensure that in polishing the operator does not destroy important occlusal contacts. If the carving has left a smooth amalgam, polishing proceeds simply and rapidly. In most cases it is not realistic to attempt a polish of the proximal surface. If it is smooth, it should be left alone except for a brief “shoeshine” using wet flour pumice and dental tape. Other areas can be finished with disks, brushes, rubber cups, and points. A flour of pumice slurry and other polishing powders is used by many operators. Abrasives incorporated into special rubber polishing cups and points are also popular. After the amalgam margins are refined with a sharp carver or finishing burr, these polishing cups and points are excellent for producing a smooth metallic surface. Using a light intermittent touch and rotary speeds in the low-to-moderate range, the operator rapidly can produce an excellent finish. A periodic reshaping of the rubber points, rounded from wear, against an abrasive disk enables the operator to properly polish grooves and fossae (Procedure 36-5).

Mercury Hygiene

Care exercised in preventing bodily harm from mercury ingestion or inhalation is termed mercury hygiene. Disregard for mercury’s toxic potential may produce injury and disease. However, in decades of use, careful handling of mercury has made its usage and dental amalgam safe.^6,7

Resin-Based Composites

Resin-based composite is tooth-colored restorative material made of complex organic resin that is hardened by light activation. Many people demand the esthetics of tooth-colored restorations.

Material

Resin-based composites are a heterogeneous blend of organic resin and inorganic filler. The resin is dimethacrylate, either bisphenol A glycidyl dimethacrylate (Bis-GMA) or urethane dimethacrylate. Filler particles are silane-coated (for adhesion and coupling) barium silicate glass, quartz, or zirconium silicate; they usually are combined with very small-sized particles of colloidal silica.¹ Light-cured composites include a photopolymerizable synthetic organic resin matrix. A radiopaque oxide is added to make the composite fillings visible on radiographs.⁸ Resin composite is often provided by manufacturers in handy dispensing devices (Figure 36-62).

Figure 36-62 Composite resin kit includes applicator, etchant and bonding agents, and various shades of composite resin.

(From Bird DL, Robinson DS: Torres and Ehrlich modern dental assisting, ed 9, St Louis, 2009, Saunders.)

Preparation

Resin composite procedures and cavity design are unique. Research has provided a means for conserving tooth structure by the discovery that retention and resistance form for resins can be created on enamel.⁹ This concept, known as micromechanical or enamel bonding, has become the basis for the routine placement of modern direct resin restorations and for such popular procedures as pit and fissure sealants and bonded veneers. As long as the prepared tooth presents an adequate enamel surface area, significant retention can be achieved. The enamel surface is shaped with instruments such as rotary burrs or diamonds to establish the desired design. Then controlled application of an acidic conditioning agent to the prepared enamel roughens the surface (acid etching). Thorough rinsing and forced-air drying displays the etched enamel (frosty appearance), which is ready to receive a primer and/or bonding resin and thereby retain a resin restoration.

Compared with enamel bonding, dentin bonding is far less predictable. Most cavities extend into dentin; the treatment of this tissue surface is in question. Lack of inorganic structure results in a weaker bond to organic collagen fibrils. The composition of dentin presents special challenges for those attempting to bond to it. Dentin is more organic than enamel and when instrumented leaves a surface covered with microscopically observable debris called the smear layer. This smear layer may interfere with strong bonding at the dentin-resin interface. In addition, a trace amount of moisture from the vital pulp is present on the dentin surface. Because restorative resins are incompatible with moisture (hydrophobic), numerous adhesive systems (hydrophilic) have been developed to chemically unite the resin with the moist dentin surface. Hybridization bonding is the bond between the dentin and the resin. Successes in this area continue to be made.¹⁰

Armamentarium

The following equipment is needed to place a resin composite:

Curing Light

A curing light is required to initiate polymerization of the resin matrix. The light is in the blue range and is transmitted from its electrical source via a fiberoptic bundle to the tip of a small wand that is positioned on the tooth surface (Figure 36-63). An intensity of 400 mW/cm² is considered adequate.¹¹

Figure 36-63 A light source for polymerization and a handheld protective shield.

Plastic Instruments

Plastic instruments are conveniently designed to carry, shape, and mold soft (plastic) materials. They may be blunt-ended instruments or flat blades not intended for firm condensation or cutting (Figure 36-64). Selection of instruments is based on the location of the cavity preparation and personal preference. Anodized instruments have been specifically developed to facilitate placement of sticky, tooth-colored materials without adherence to the instrument.

Figure 36-64 Common plastic instruments.

Indications for Resin-Based Composite Restorations

Class I (Occlusal) and Class II Restorations

Client demands for natural-looking teeth have resulted in use of resin composites for restoring posterior teeth. Current generation resin composites are specifically designed for restoring either anterior or posterior teeth. Successful placement of Class II resin composite restorations still poses challenges that make some dentists hesitate to use the material as a routine restorative for these situations.¹²

Class II composite restorations are extremely technique sensitive. In addition to the need for very careful isolation and moisture control, manipulation of the matrix is critical. Establishing a positive proximal contact that is physiologically contoured is one of the biggest challenges facing the operator. Placement, curing, and finishing of resin composites demand four-handed dentistry at its best.

Class III and IV Restoration Placement and Finishing

Before the rubber dam is applied, shade selection is done to match the color of the composite to the dentition in which the restoration is being placed.

A typical Class III carious lesion is illustrated in Figure 36-65. The preparation is made to satisfy all principles but with emphasis on conservatism in outline form. The plastic nature of the resin material allows it to be placed under virtually no force, and specially designed delicate instruments are available for placement and finishing. In the maxillary anteriors, access is usually from the lingual direction, and care is taken to preserve the marginal ridge whenever possible. In deep restorations, dentin coverage with glass ionomer cement helps decrease microleakage and the possibility of sensitivity by bacterial invasion (Figure 36-66; Procedure 36-6).

Figure 36-65 Class III carious lesion depicted. Caries is shown invading the dentin, but the cavity does not endanger the incisal corner.

Figure 36-66 Lingual view of the completed Class III cavity preparation. The dentin is protected by a cavity liner, an enamel bevel has been placed, and the rubber dam retracts the gingiva to provide access.

Figure 36-67 The etched enamel receiving a coating of bonding resin. A matrix separates the cavity from the adjacent tooth and is contoured and stabilized by a wedge placed interproximally.

Figure 36-68 Placement of increments of resin composite into the preparation. The resin must be adapted into the recesses of the cavity and built against the matrix and cavity walls.

Figure 36-69 Cavity filled to slight excess, cured, and prepared for finishing.

Figure 36-70 Contouring the resin composite with a disk to achieve the final form. The wedge and matrix have been removed.

Figure 36-71 Damage to the tooth structure occurs if due caution is not exercised with the use of a burr in the finishing procedure.

Figure 36-72 Finished Class III resin composite restoration.

Figure 36-73 Glass ionomer products are supplied in various forms, including base and catalyst for hand mixing and triturated pre-encapsulated.

(From Bird DL, Robinson DS: Torres and Ehrlich modern dental assisting, ed 9, St Louis, 2009, Saunders).

Figure 36-74 Placement of the resin-modified glass ionomer to slightly overfill the cavity.

Figure 36-75 Positioning the clear cervical matrix over the cavity and expressing excess resin-modified glass ionomer at the edges of the matrix.

Figure 36-76 Final contouring of the restoration with a disk.

Figure 36-77 Root damage from improper disking.

Figure 36-78 Finished resin-modified glass ionomer restoration.

Figure 36-79 Trim the margin of the crown with crown scissors.

Figure 36-80 Crimping pliers are used to adapt the margin of the crown.

Figure 36-81 Overfill the crown with cement.

Figure 36-82 Use knotted floss and a scaler or explorer to remove excess cement after seating the crown.

Procedure 36-6 PLACING AND FINISHING A RESIN COMPOSITE RESTORATION

EQUIPMENT

Personal protective equipment

Protective eyewear for client

Isolation materials

Glass ionomer cavity liner or sealer as needed

Conditioning agent (acid gel)

Priming agent

Bonding resin

Resin composite

Resin surface coating

Matrix system

Dispensing syringe

Curing light and protective shields

Plastic instruments

Finishing burrs and disks

Articulating paper

STEPS

1. Query client regarding expectations; explain nature of resin composites.

2. Select composite shade, place small amount of material on the tooth near the lesion and cure it; involve client in shade selection.

3. Place rubber dam.

4. After cavity preparation, apply cavity liner, sealer, and/or base as needed.

5. Position a clear, plastic matrix strip between the preparation and the adjacent tooth.

6. Dry tooth and apply etchant to the entire cavity surface according to manufacturer’s instructions. Rinse with an air-water spray for at least 15 seconds; dry with forced-air drying. Reposition matrix as necessary; position a wedge interproximally.

7. Inspect the peripheral etched pattern.

8. Apply thin coats of primer to etched surfaces according to manufacturer’s instructions, and lightly dry.

9. Apply a thin coat of bonding resin to primed surface; spread resin over etched enamel with a small brush or sponge and a gentle stream of air (Figure 36-67).

10. Place special protective eyeshield on operator, assistant, and client to avoid eye damage during the curing that is about to start.

11. Polymerize bonding resin with curing light for 15 to 20 seconds; light wand should be as close as possible without direct contact. Careful inspection of cured bonding resin will reveal a slightly tacky surface. This very thin layer of resin is unable to completely polymerize because of the influence of air. It will rapidly polymerize once covered by resin composite or a matrix strip and reexposed to the curing light.

12. Remove cap from resin composite dispensing device; express small amount of selected resin composite onto a small paper pad; replace cap. Many systems are pre-encapsulated.

13. With a plastic instrument, or pre-encapsulated mixture placed in dispensing gun, place increment of resin (no more than 2 mm thick) in preparation; adapt to walls and margins; cure this first increment for 20 to 30 seconds (Figure 36-68).

14. Continue to add and cure increments, building form to a slight excess in contour. In small cavities final form may be achieved by firmly wrapping clear matrix against tooth and curing through it (Figure 36-69); remove wedge and matrix.

15. Contour restoration with finishing burrs and disks, exercising care to avoid tooth damage (Figures 36-70 and 36-71).

16. Remove rubber dam and check for occlusal prematurities on restoration. Lingual high spots can be carefully reduced with a large, round finishing burr or a football-shaped fine diamond.

17. Polish accessible parts of restoration with polishing disks; examine gingival sulcus and remove debris.

18. Condition restoration surface with conditioning agent.

19. Apply resin surface coating with a cotton pellet or foam applicator; cure for 10 seconds.

20. Show client restoration; explain shade discrepancies (Figure 36-72).

Class V Restoration Placement and Finishing

A perplexing problem in restorative dentistry is the course and treatment of lesions at the gingival margin. Abrasion, erosion, dental caries, or combinations of these can create defects that are difficult to properly restore and often require isolation with special rubber dam retainers because they frequently extend into the gingival sulcus. Shade selection is accomplished before the rubber dam placement. The rubber dam is placed in a routine manner. To properly isolate the lesion, it may be necessary to retract the free gingiva to expose the gingival margin of the cavity. Several rubber dam retainers work well for this purpose. After etching, rinsing, and drying the prepared cavity, following the manufacturer’s instructions, the preparation is covered with one or more coats of a priming agent and lightly air-dried. Then the bonding resin is spread gently over the internal surface, lightly air-dried, and cured for 15 seconds. This is followed by incremental placement and curing of the resin composite. Contour can be developed by tamping the final increments into place with an instrument tip that has been dipped in bonding resin to prevent sticking to the composite. This procedure produces a smooth, contoured surface that requires a minimum of finishing. After final curing, careful shaping and polishing are accomplished with finishing burrs and disks. The gingival sulcus should be cleansed of any debris and surface coating material before the client is dismissed.

Resin-Modified Glass Ionomer

Glass ionomer cements are available as cavity liners as well as definitive restorations. Like all cements, they undergo dissolution when exposed to saliva. To compensate for the tendency to dissolve and improve their use as a restorative material, glass ionomer cements have been modified. The improved product is called resin-modified glass ionomer (RMGI). All glass ionomer dental materials release fluoride ions. As a result, recurrent caries is rarely seen at the margin of a RMGI restoration. RMGIs offer enhanced esthetics, less solubility, and greater strength than glass ionomer cements but retain some of their fluoride-release characteristics. RMGIs are an important class of materials for restoration of primary teeth.¹³

Preformed Stainless Steel Crowns

Research has shown that stainless steel crowns used to restore primary molars have a greater longevity than amalgams.^14,15 Some REF dental hygienists place stainless steel crowns within their scope of practice (Procedure 36-9).

Procedure 36-9 PLACING A STAINLESS STEEL CROWN

EQUIPMENT

Personal protective equipment

Protective eyewear for client

Isolation materials

Stainless steel preformed crowns

Crown trimming scissors

Crimping pliers

Resin-modified glass ionomer cement

Floss

Articulating paper

STEPS

1. Evaluate prepared tooth for size.

2. Correct size is selected by measuring the mesiodistal width between contact points of a matching tooth in mouth.

3. Choose smallest crown that will fit

4. To seat, place crown lingually and adapt it over the occlusal and buccal aspects of prepared tooth.

5. Use firm pressure to seat crown. May hear an audible click as it springs over gingival undercut area of preparation.

6. To evaluate fit, observe marginal gingiva. It will blanch somewhat with a well-fitting crown. If excess blanching is observed, crown will have to be trimmed.

7. In a properly seated crown, margin should extend approximately 1 mm subgingivally. To trim crown, scribe a line where marginal gingival hits crown with an explorer.

8. Trim crown 1 mm below scribed line. Use crown scissors or an abrasive wheel to trim crown (Figure 36-79).

9. Use crimping pliers to adapt edge of crown for a tighter fit (Figure 36-80).

10. Seat crown once more to evaluate fit.

11. Crown is now ready to be cemented.

12. Use resin-modified glass ionomer cement. Fill entire crown with cement (Figure 36-81).

13. Excess cement will flow out from margins as crown is seated.

14. Use an explorer, a scaler, and knotted floss to remove excess cement (Figure 36-82).

15. Check occlusion using articulating paper.

Indications

Stainless steel preformed crowns are indicated for primary molars where an amalgam is likely to fail, for extensive caries damage involving multiple surfaces of the tooth, and after pulp or endodontic therapy.^16,17 Stainless steel preformed crowns provide a suitable medium-term option when financial considerations prevent use of a permanent cast restoration in permanent molars.¹⁸

Materials and Armamentarium

Materials needed include the following:

Preformed crowns

Trimming scissors

Crimping pliers

Glass ionomer cement

Liners

Liners are liquidlike materials applied in thin coatings (<0.5 mm) that act as cavity sealers and provide beneficial functions such as fluoride release, adhesion to tooth structure, and/or antibacterial action that promotes the health of the pulp.¹⁹ Calcium hydroxide preparations are commonly used to protect the pulp in deep cavity preparations and in situations when the pulp has been exposed, to stimulate the vital pulp to heal if the wound is small and clean. These liners are easily prepared and are usually supplied by manufacturers in small tubes (Figure 36-83). Equal amounts of agents are dispensed onto a small pad, quickly mixed, and then specifically placed on the dentin or over the pulp exposure (Figures 36-84 and 36-85). Because these materials typically do not resist compressive forces, an additional hard base material is often used for protection.

Figure 36-83 A popular calcium hydroxide product, an applicator, and a mixing pad.

Figure 36-84 Equal amounts of the calcium hydroxide base and catalyst have been mixed.

Figure 36-85 Placement of mixed calcium hydroxide in the deeper areas of the cavity preparation.

Sealers

Cavity sealers are used to seal dentinal tubules to protect the pulp from chemical irritation. Sealing of dentinal tubules is accomplished by using bonding resins or liners.¹⁹ Dentin bonding agents provide a hybridization bond formed between the restorative material and the tooth structure (hybrid layer) that has been found to better seal tubules and provide some retentive strength for resin composites when used (Figure 36-86).

Figure 36-86 A popular dental liner.

Bases

Bases, materials placed to provide thermal insulation and support under metallic restorations, must be strong enough to resist occlusal forces and, in the case of amalgam, resist firm condensation. This category includes zinc phosphate, glass ionomer cements, and resin composites. Bases of zinc phosphate cement have served dentistry well, providing dependable support and insulation under metallic restorations (Figure 36-87). The rationale for its use in preventing sensitivity, however, has become questionable in recent times. Gaining a seal of the dentinal tubules to prevent microleakage is believed to be far more important in controlling postoperative sensitivity than is physical insulation. When zinc phosphate cement is used, its preparation requires attention to detail.

Figure 36-87 A popular zinc phosphate cement.

Figure 36-88 Retraction cord looped around the lingual of the prepared tooth.

Figure 36-89 Periodontal probe holds packed cord in place while side of explorer rotates cord into place in the sulcus.

Figure 36-90 Explorer on left properly permits the cord to roll into place, but the round-ended instrument on the right permits the cord to improperly pop up on the sides.

Figure 36-91 A small end of the top cord extends out of the sulcus.

Compared with zinc phosphate cement, glass ionomer cements require less time to prepare and bond to dentin, achieving a desirable seal. Most glass ionomer cements are available in a self-dispensing form and do not require manual mixing. However, when these cements are manually prepared, mixing and manipulation times are critical.

Resin composite materials are handled in a manner similar to glass ionomer cement bases. However, more care is required in ensuring retention because resin composites adhere only by micromechanical retention. Most of them are available in cartridge (compule) form and can be mixed mechanically in a few seconds. These may be chemical-cured or light-cured materials. For best adhesion the cavity is cleansed with a 10- to 20-second application of a conditioning agent (polyacrylic acid) to remove microscopic debris (smear layer). After rinsing and gentle drying of the cavity, the mixed cement is injected into the cavity and molded with a suitable instrument to the desired form while it is in a gel state. If chemical-cured, the material hardens in a few minutes, at which time it should be coated with a special varnish provided with the resin composite system to prevent moisture loss or gain. If the material is light-cured, the operator has time to mold it before light-activating it. Depending on the specific product, amalgam can be condensed on the set base within 4 to 10 minutes.

Armamentarium

Gingival Tissue Management

For any preparation for impression, the depth of the gingival margin of the preparation must be evaluated in relation to the gingival sulcus. In addition, the health and flexibility of the free gingival tissue must be assessed. Normal, healthy tissue does not require pretreatment before the tissue retraction procedure. Hemorrhagic tissue, however, may require treatment before retraction or postponement of the retraction and impression procedures. Hemorrhaging may be controlled using an astringent and coagulation liquid such as Monsel’s solution (15% ferric subsulfate) or Astringedent X (20% ferric subsulfate).

Retraction Cord Placement

Tissue retraction can be accomplished using a one-cord or two-cord retraction technique. The two-cord technique is preferred unless the depth of the sulcus or the tightness of the free gingival tissue, especially on the facial surface, does not permit placement of the second cord.¹⁵ The bottom cord, smaller in diameter, acts to control seepage and promote slight lateral displacement of the sulcular base. This cord is left in place during the impression procedure; therefore placement apical to the gingival margins of the preparation is critical. The top cord, larger in diameter, provides enhanced lateral displacement of the gingival tissue and is removed before the impression procedure. Adequate tissue retraction is achieved within 8 to 10 minutes. Each layer of cord is placed using the same technique. There are times when a small amount of anesthetic is needed for tissue retraction, such as for lingual areas of maxillary teeth. In an effort to avoid a potentially painful lingual injection, the retraction cord can be soaked in a mixture of 12.5 g of aluminum chloride crystals with 50 mL of 4% lidocaine (Procedure 36-10).

Temporary Materials and Placement Techniques

Temporary Stopping

Temporary stopping is a thermoplastic compound that is quickly and easily prepared and placed (Figure 36-92); it is best used to seal small, shallow cavities requiring temporary restoration for periods of not more than 2 weeks.

Figure 36-92 A popular temporary stopping product.

The placement of temporary stopping requires that the end of a stick of material be slowly warmed over an alcohol flame until softened, then allowed to cool until it can be handled by the operator. Small increments are rapidly molded in the fingers and positioned on the tip of a placing instrument (Figure 36-93). These increments are rapidly and firmly packed into the cavity until the material fills the preparation. Minor shaping of the restoration to restore the tooth to the original occlusion or anatomy is done with a warm, not hot, instrument tip.

Figure 36-93 Temporary stopping material has been warmed over an alcohol flame until soft and then positioned on the tip of a placing instrument.

Reinforced Zinc Oxide with Eugenol

Reinforced zinc oxide with eugenol readily restores intermediate-size cavities that require a more durable material; it is prepared with a mixture of zinc oxide powder and eugenol liquid (Figure 36-94). The insulating properties of the hardened zinc oxide mass and the obtundent effect of the eugenol result in a material that protects the vital pulp against chemical and thermal insults. Reinforced zinc oxide with eugenol is relatively easy to prepare and place and is reliable for interim periods of a few months.

Figure 36-94 A popular reinforced zinc oxide with eugenol material.

Figure 36-95 Properly mixed reinforced zinc oxide with eugenol ready for placement.

Figure 36-96 Reinforced zinc oxide with eugenol being placed in cavity preparation.

Figure 36-97 Final adjustment to the occlusal aspect of the temporary restoration with a carver.

The powder and liquid are mixed on a nonabsorbent pad according to manufacturer’s instructions. Firm pressure on the spatula is needed to thoroughly mix the material. Properly mixed, the material is thick and claylike. The material is then rolled with the fingertips (on the pad) into a cylindric form. Increments can be pinched off the end of the mass with a placing instrument and firmly packed into the preparation until it is full (Procedure 36-11).

Procedure 36-11 PREPARING REINFORCED ZINC OXIDE AND EUGENOL TEMPORARY RESTORATIONS (CLASS II CAVITY PREPARATION)

EQUIPMENT

Personal protective equipment

Protective eyewear for client

Isolation materials

Tofflemire matrix system

Petrolatum

Reinforced zinc oxide and eugenol

Nonabsorbent mixing pad

Plastic instruments

Cotton pellets and rolls, dry aids

Finishing burrs

Carving instruments

Articulating paper

STEPS

1. Isolate operating site as appropriate.

2. Prepare Tofflemire matrix system.

Apply thin coat of petrolatum on the inside of the matrix band; position matrix, secure it, and place interproximal wedges as needed.

3. Use manufacturer’s instructions for measuring and mixing.

4. Prepare mix; when material reaches consistency of firm clay, carry an ample amount to cavity with a plastic instrument. Firmly adapt rubbery material to all walls of cavity with a placement instrument (Figures 36-95 and 36-96).

5. Fill cavity to slight excess; shape occlusal anatomy by using a moist cotton pellet in cotton forceps to create a general anatomic form.

6. When material has hardened, remove wedge(s), retainer, and matrix band; apply pressure apically on the temporary restoration to counteract removal of band.

7. Check proximal and gingival margins for excess material and remove with sharp, narrow-bladed carving instrument.

8. Remove isolation materials; evaluate premature occlusion on temporary restoration with articulating paper and adjust as necessary with large, round burr and carving instruments (Figure 31-97).

9. Examine gingival sulcus for debris and remove as necessary; excess material at gingival margin can be removed using a bladed instrument such as the ½ Hollenback or IPC carver.

Luting Agents

Indirect restorations are fabricated in the dental laboratory on dies made from impressions of prepared teeth. These restorations include crowns and inlays made of rigid substances such as metal, cast ceramic, or porcelain. When these restorations are completely seated, all margins should intimately fit. However, between the restoration and the cavity walls exists a minute space filled with a luting agent (cement) that, when set, prevents the indirect restoration from loosening. Dislodging forces of occlusion and mastication are resisted by this firm interface of cement. Without a proper luting agent, castings leak, loosen, and fail.