polishing of anterior composite resin restorations

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Polishing of Anterior Composite Resin Restorations

Written by Howard E. Strassler, DMD, FADM, FAGD and Judith Porter, DDS, EdD

Tuesday, 01 April 2003 00:00

The aesthetic appearance of a composite resin restoration depends upon shape, color, and

gloss of the restoration achieved by finishing and polishing. When composite resins were first

introduced in the late 1950s and early 1960s, they were self-cured and macrofilled with

particles in the 25 to 50 µ m range. In most cases, the filler particles were quartz. These

composite resins, once contoured, had little surface gloss, and the patient sensed roughness

when their tongue touched the restoration.

The introduction in the late 1970s of visible light-cured composite resins with smaller

diameter filler particles of synthetic, softer glasses made composites more polishable. These

materials allowed the clinician to provide patients with more natural and aesthetic tooth-like

restorations in the anterior region of the mouth. As a result of changes in the polymerizationchemistry, visible-light cured composite resins demonstrated improved color stability. Light

activation was generally initiated when a blue light with a wavelength of 460 to 470 nm was

absorbed by a photo-initiator, usually camphoroquinone (CQ). The use of CQ combined with

an organic amine resulted in a chemical reaction so the composite resin hardened. This light-

activated reaction eliminated the need for the tertiary amines that were present in the early

self-cured resins. The tertiary amines contributed to unaesthetic color changes that

characterized these restorative materials.

In the last 15 years, manufacturers have introduced a wide variety of composite resins with

varied applications in both the anterior and posterior regions (see Table 1). For anterior

restorations, microfilled composites and hybrid composite resins have become acceptedstandards. Microfilled composites offer high polishability with tooth-like translucency, but

unfortunately are radiolucent. The microfilled composites are polishable and maintain their

luster as a result of the inclusion of 0.04-µm colloidal silica particles within the polymer

matrix (homogenous microfill) or mixed with the polymer matrix, light cured, and then

crushed to make a prepolymer filler that is an organic filler within the microfilled composite

(heterogenous microfill). The small fillers and resin-rich surface promote high polishability.

Microfilled composites are generally loaded 32% to 50% by volume and have greater

polymerization shrinkage, higher water sorption, and a higher coefficient of thermal

expansion and contraction than hybrid composites.1



Hybrid composite resins combine microfiller particles (0.04-µm fumed silica) with microfine

glass fillers with an average particle size diameter of less than 2 µm. Typically these

composites are loaded 58% to 75% by volume and are radiopaque. This mixture of fillers

accounts for the excellent physical properties, including high polishability, as compared to

macrofilled composites.2 An important problem associated with hybrid composite resins is

their inability to maintain a gloss when exposed to toothbrushing with toothpaste or

application of prophylaxis pastes.3-6

Although microfilled composites maintain their gloss, these composites are susceptible to

fracture in high-stress-bearing areas.7 Consequently, a highly polishable composite resin with

optimal physical properties was needed for anterior and posterior restorations.



NEW GENERATION COMPOSITE RESIN

Recently, a new generation of hybrid composite resin has been introduced. These materials

have been categorized as nanofilled, with filler particles with a diameter in the 0.005- to 0.1-

µm range (Table 2). The nanofilled composites have physical properties equivalent to the

original hybrid composite resins, good handling characteristics, and greater polishability.8,9

These nanofilled composites offer an excellent alternative to microfilled composites because

they can be polished to a toothlike translucency.10 For anterior restorations, both microfill and

nanofilled hybrid resins can be expected to provide good color stability, resistance to stain,

low wear, and good polishability.2,8

While the new nanofilled composites are supplied with basic shades, they also have incisal,

enamel, and dentin shades. With the introduction of these composites, manufacturers have

provided specialized shade guides that help the clinician select the mix of shades to be used

in specialized circumstances, such as building on class IV incisal edge fractures from the

inside out and stratified building of completed facial veneers for aesthetic bonded

restorations. Examples include Filtek Supreme (3M ESPE), which provides a comprehensiveshade selection wheel that is used once the basic shade has been selected from a Vitapan

(Vident) classical shade guide, and Esthet-X (DENTSPLY/Caulk), which provides a

comprehensive, expanded shade guide that matches bleached teeth and includes some darker

shades than the traditional Vitapan guide. These advanced composite resins have been

formulated to be more sculptable and easily placed, with minimal slump and very little

tackiness.



THE IMPORTANCE OF FINISHING AND POLISHING

The final aesthetic appearance of any composite resin is dependent upon the artistic abilities

of the clinician in (1) choosing the correct shade or shades of composite resin to mimic thecolor and appearance of the teeth, and (2) shaping and contouring of the restoration. The

restoration’s ability to imitate the appearance of the tooth and/or adjacent teeth also depends

upon the proper finish and polish of the restorative to its highest luster.11,12 Research has shown

that the technique for polishing composite resins to their optimal smoothness and gloss is

specific to the type of composite resin and the product.10-17

Barkmeier and Cooley18 evaluated the ease of polish and surface finish of 4 heterogenous

microfills and 1 homogenous microfill. They found all 5 microfills had no difference in ease

of finish, but the homogenous microfill produced the smoothest surface. Hoelscher and

coworkers19 compared 3 different finishing systems employed with 4 aesthetic materials

(including glass ionomers and a hybrid and a microfill composite resin). Their findingsindicate that a finishing bur left the roughest surface, while abrasive disks, when used from

coarse to fine, yielded the smoothest finish of all materials tested. Setcos, Traim and Suzuki20

compared several disk systems used to polish hybrid and microfilled composites. Regardless

of composite type, the sequential use of disks from coarsest to finest produced the smoothest

surfaces.

The principles governing the polishing of composite resins are similar to those used to polish

dental metals. Unlike metals that have a homogenous alloyed surface and a uniform hardness,

however, composite resins are composed of resin matrix and filler particles. In some cases,

the resin matrix and fillers have different hardnesses. While composite resin finishing

systems can be used on metals, metal finishing and polishing systems should not be used for

composites in order to avoid undesirable staining and discoloration. The abrasive particles

used to polish composites are material specific. Similar to metal polishing, the sequence of

polishing for composite resin progresses from coarsest abrasive to finest.

Finishing and polishing devices and instruments can be classified as...

(1) coated abrasives; eg, abrasive finishing disks and strips;

(2) rotary cutting devices, eg, carbide finishing burs;

(3) rotary submicron particle diamond finishing abrasives;

(4) reciprocating abrasive tips; eg, laminated abrasive flat paddles;

(5) rubberized embedded abrasives; eg, rubber or silicone rotary points;

(6) hand instruments, and;

(7) abrasives suspended in a polishing paste.

No matter which abrasives are selected, the rule of coarsest to finest must be followed. Table3 has a partial listing of instruments, devices, and materials for polishing composite resins.



The goal when placing a composite resin is minimal finishing and polishing. While this is not

difficult with routine anterior restorations (class III and class V), for larger, more involved

restorations (class IV and complete facial veneering, especially for multiple teeth),

significantly more contouring and finishing is usually required. Typically, for these larger

restorations the sequence for finishing and polishing involves gross contouring, shaping with

finishing burs and submicron finishing diamonds with a high-speed handpiece, followed byadditional finishing with abrasive discs and/or rubber points. For long incisal-gingival

restorations, narrow, long finishing burs or diamonds with safe-tipped ends allow the

establishment of aesthetic curved surfaces. While finishing burs and diamonds can be used

either wet or dry, the authors prefer using them dry with light pressure, with the dental

assistant suctioning the composite “dust” during the procedure. Working with a dry field

provides better visualization of shape and contour of the composite resin surface.

Judicious use of coarse and medium grit finishing disks using only small sections of the disk

allows the same level of control. Today, most disks have a small metal hub to reduce the

chance of accidentally hitting the composite with the hub. Some manufacturers (Shofu and

Brasseler) have placed their disks on silicone sheaths that slip over the metal mandrel,thereby eliminating the potential to mar the composite resin surface. Additional finishing of

facial and lingual surfaces can be accomplished with specialized rubberized polishers in

flame, disk, and cup shapes. These shapes provide access to the different tooth contours.

These are used on a latch-type contra-angle handpiece. It is important whenever using

abrasive systems that the surface of the composite resin be physically debrided of composite

and abrasive debris with a damp cotton roll or gauze. If only an air-water spray is used, some

of the debris will remain on the surface and interfere with polishing when sequentially using

the next finest abrasive grit.

Interproximal finishing and polishing are accomplished with gapped finishing and polishing

strips covered with aluminum oxide abrasive particles, or with metal strips covered with

submicron diamond particles. Occasionally, even with the use of a matrix strip, the

restoration may bond to the adjacent teeth, literally splinting the teeth together. In these cases,

there are specialized accessories that allow the clinician to separate the teeth without

damaging the restoration. Included here is an ultra-thin stainless steel saw blade mounted in a

handle (Cerisaw, Den-Mat). This mini-hacksaw and handle allows for total control of the

instrument while gently sawing through the interproximal resin. When using a saw, a gingival

wooden wedge should be placed between the teeth to protect the gingival papilla. Den-Mat

also places diamond strips in the CeriSaw handle to finish interproximal surfaces of resin

restorations and ceramic veneers. In addition, Axis Dental combines a gapped diamond-

containing metal finishing strip with saw teeth on the strip.

Another useful device to help separate interproximal contacts for placement of matrix strips

or gapped finishing strips is the Contact Disc (Centrix). This thin, rigid disk can be inserted

from the incisal, occlusal, or facial directions to force the teeth apart. If excess composite

resin is present, the disk will create space to allow a matrix strip to be placed without

bleeding, as may occur when using a gingival wooden wedge to accomplish the same task. In

the presence of excess interproximal composite resin, the disk will break away excess resin

without damaging the restoration. Premier Dental Products has developed a diamond-

impregnated thin disk (CompDisk) that not only creates space with rapid separation, but can

also be used for interproximal finishing or cleaning interproximal surfaces before bonding.



Occasionally, after placement of the composite restoration, finishing the margin is best

accomplished with a hand instrument or by using a specialized reciprocating handpiece with

a flat abrasive paddle. Carbide-tipped hand instruments (Brasseler; Den-Mat), restorative

knives (Hu-Friedy), or scalpel blades with shapes that allow access to the margin of the

restoration will allow the clinician to remove excess restorative material in a more controlled

manner than with rotary burs or diamonds.12,21 Carbide carvers are especially useful formarginating composite resin restorations when only minimal excess is present. In

inaccessible areas such as the gingival margin of an interproximal surface, specialized

instruments and devices such as a reciprocating handpiece (Profin, Dentatus) with a flat

Lamineer abrasive tip can be used.21,22 Lamineer tips come in a variety of submicron abrasives

for finishing and polishing the cervical margin of the restoration. The flat tips can also be

used to finish and shape facial surfaces and incisal embrasures.

Final polish of the composite resin surface to its most lustrous finish can be accomplished

using disks with the finest aluminum oxide abrasive. Using a disk will not only smooth the

resin surface, but will also heat the surface, creating a high luster. This heating is sufficient to

allow the polymer matrix to reach its glass transition temperature. This phenomenon gives thecomposite resin a glassy appearance. Also, a composite resin can be polished with specialized

composite resin polishing pastes that contain either very fine aluminum oxide abrasive

particles or diamond particles. This is best accomplished with foam cups, felt-mounted disks,

or fine goat-hair brushes. If the surface of the restoration is generally smooth, disks work

well. For surfaces that have anatomic variations such as lobular forms or striations, composite

polishing pastes work best.

Figure 1a. Facial view of the

maxillary anterior teeth. The

central incisors are lingually

positioned and the lateral

incisors are rotated distally.

Figure 1b. Palatal view

showing the misalignment of

the incisors.

CASE REPORT

During the restorative treatment consultation, the patient was presented with 3 options —

ceramic crowns, porcelain veneers, or direct placement composite resin. Adhesive bonding

with composite resin and ceramic veneers are alternative treatments for aesthetic correction

of tooth malposition in the anterior area.23,24 Because of financial considerations, the patient

chose direct placement composite resin restorations.



Figure 2a. Palatal view of cast

demonstrating malaligned

incisors.

Figure 2b. Stone has been

removed from the cast to

simulate tooth preparation.

Figure 3a. Diagnostic buildup

with composite resin.

Figure 3b. Palatal view of the

buildup.

During the treatment planning phase, study casts were used to further evaluate tooth position.

The maxillary incisors were reduced on the casts to determine how much tooth preparation

would be needed to allow for adequate composite resin to align the incisors (Figures 2a and

2b). A diagnostic buildup with composite resin was performed to assess tooth shape,

proportions, and widths, and for patient acceptance (Figures 3a and 3b). When the patient

accepted the proposed treatment, he was scheduled for restoration with a direct placement,nanofilled hybrid composite resin (Point 4, Kerr).

Before tooth isolation, a shade was selected with a Vitapan shade guide (Vident). This

selection was checked by placing an increment of composite resin most closely matching the

shade of the maxillary canine on the lateral incisor and light curing that increment. Like many

of the new generation of nanofilled composite resins, Point 4 offers regular shades, opaque

shades, translucent shades, and bleaching shades. Although Point 4 has very little color

change when light cured, some composite resins change shade when light cured because of

removal of the orange-yellow photoinitiator (camphoroquinone) during the polymerization

process. Accurate shade selection is a critical step when placing anterior composite

restorations.

Figure 4. Preparation of

maxillary incisors.



The teeth were isolated using a split rubber dam. Split rubber dam involves punching holes

for rubber dam placement and then cutting through the septa between holes with a scissor. A

bite block was placed. Use of the rubber dam combined with a bite block improves patient

comfort and affords better access when preparing and restoring anterior teeth with direct

bonded composite resin. Here, the teeth were prepared with a thin, medium-grit flame-shaped

diamond (Revelation 653-016, SS White Burs) on a high-speed handpiece with water spray(Figure 4).

Before acid etching, dead soft stainless steel metal matrix, 0.001-inch thick, was placed distal

to the maxillary central incisors. A piece of Tofflemire stainless steel rigid matrix (0.002-inch

thick) was cut into a small rectangular strip and was placed between the central incisors. This

more rigid strip holds the correct orientation of the midline.

Figure 5. Etched facial

surfaces of maxillary incisors.

Figure 6. Application of

adhesive to etched tooth

surfaces.

The tooth surfaces were etched for 15 seconds with a 32% phosphoric acid etchant and then

rinsed with an air-water spray for 15 seconds. The etched tooth surfaces were dried, leaving a

slightly frosty appearance to the enamel, and the dentin was moistened, leaving a glossyappearance (Figure 5). An enamel/dentin adhesive (Optibond Solo Plus, Kerr) was applied to

the facial surface of the etched enamel (Figure 6), and then light cured for 20 seconds with an

Optilux 501 (Demetron/Kerr) curing light. The nanofilled composite resin hybrid (Point 4,

Kerr) was placed on the facial surfaces of both central incisors and sculpted with a thin, broad

plastic filling instrument (PFIAB1, HuFriedy). This instrument allows for smooth shaping of

the broad facial areas of incisors. The instrument was lightly wetted with a coating of

adhesive resin to prevent the composite resin from sticking to the instrument and pulling

away from the enamel surface. The composite resin was light cured for 20 seconds using a

wide-angle light probe tip so that the entire facial surface could be polymerized. After

placement of the composite resin on the central incisors, the lateral incisors were restored

using the same protocol.

FINISHING AND POLISHING

Many manufacturers provide kits containing finishing burs, diamond abrasives, rubberized

abrasives, and disks that give the clinician an orderly sequence of finishing and polishing

instruments. There is no one approach to the finishing and polishing of composite resins, but

a general rule is to proceed from coarse to fine grit size.



Figure 7. Long, thin composite

resin finishing bur trimming

the facial surface.

Figure 8. Shaping of the

gingival margin with a thin

needle shaped finishing bur.

Figure 9. Fine diamond

finishing bur for contouring the

gingival margin.

In this case, the facial surfaces were contoured using a long, narrow, safe-ended, multifluted

finishing bur (7204, SS White Burs) (Figure 7), but a submicron diamond abrasive with a

similar shape could also have been used. The gingival margin was contoured and marginated

with a shorter, thin-needle shaped finishing bur (CFT 2, SS White Burs) (Figure 8). Another

popular choice for shaping facial surfaces of veneers and class IV restorations is the ET seriesof finishing burs and diamonds (Brasseler USA). The choice of finishing bur and diamond

abrasive is usually made by the practitioner based upon experience. Finishing burs can have

as few as 8 or 12 blades for gross reduction. For finer finishing, 16- or 30-bladed burs are

available. Diamond composite finishing abrasives usually have a diamond particle size of

approximately 30 µm for fine grit, 15 µm for extra-fine grit, and 8 µm for ultra-fine grit. Note

that a thin, new finishing bur can cut aggressively into a facial surface. A composite resin

finishing bur dulls to the ideal after 2 sequences of autoclaving. To further finish the gingival

margin, a flame-shaped fine finishing diamond (862-016, SS White Burs) (Figure 9) was

used as it allows better access to the gingival margin without nicking the root surface. After

the fine diamond was used, the composite surface was further finished with a flame-shaped

extra-fine bur and then a flame-shaped ultra-fine diamond.

Figure 10. Coarse disk

shaping the incisal edge.

Figure 11. Disk shaping the

facial and incisal embrasures.



The incisal edge was shaped and the length determined using a coarse disk (Soflex XT disk

No. 2381C, 3M ESPE) (Figure 10). The best technique for shaping the incisal edge is to have

the patient seated in an upright position that mimics how the incisal edges are visualized. The

disk should be oriented with a slight lingual inclination following the chisel shape of the

incisal edge of an intact incisor. The incisal embrasures and facial embrasures were

established using a thin, flexible diamond disk (Vision Flex Disc, Brasseler USA) (Figure11). These areas can also be shaped with a reciprocating handpiece (Profin) and an “S” series

knife edge lamineer tip. Once shaped, the areas were finished using successively smoother

disks, from a medium to fine to finest grit.

Figure 12. Safe-sided

Lamineer tip on reciprocating

handpiece shaping the gingival

interproximal embrasure.

One of the most difficult areas to access when finishing any aesthetic restoration is the

gingival margin of an interproximal surface. Finishing strips do not work well because of

difficulty in accessing this area. In this case, the Profin with a Lamineer tip was used in the

gingival interproximal areas because the reciprocating handpiece, with its back and forth

motion, provides the control needed to safely finish and polish the root surfaces withoutnotching (Figure 12). Finishing burs on a high-speed handpiece, if not used correctly, can

easily notch the root surface. Even the thinnest finishing burs or submicron diamond

abrasives are rounded and can notch a root surface. The Lamineer tips are safe-sided and are

available in decreasing diamond abrasive grits to allow finishing and then polishing of the

gingivoproximal area.

There are times when a rotary instrument or even a reciprocating instrument does not have

complete access to the interproximal surface. For these special situations, a hand instrument

allows for fine control, precision placement, and effective removal of excess composite resin.

Hand instruments for this purpose include carbide-tipped composite instruments (with

specialized shapes to access different tooth surfaces), composite carving knives, and a No. 12

scalpel blade.21

The finishing and polishing of the interproximal surfaces of composite resin restorations

require the same attention given to accessible surfaces. Care should be taken not to remove

excessive composite resin, resulting in an open proximal contact. Interproximal strips can be

used to shape and contour the interproximal contact area, thus maintaining the contact. When

using finishing strips, always proceed from medium abrasive grit, to fine grit, to the finest

grit. Gapped finishing strips work best as they allow ease of placement between the teeth. If

difficulty is encountered introducing the strip through the contact, a plastic filling instrument

can be used to rapidly separate the teeth, and then the finishing strip is slid below theinterproximal contact area. If a diamond abrasive-gapped strip (eg, Gateway Strip, Brasseler)



is used, additional care must be taken to not remove tooth structure when finishing the

interproximal areas. These diamond-impregnated strips also work well for removing stain on

interproximal tooth surfaces before the bonding procedure.

Figure 13. Finishing cup

smoothing the facial surface of

the composite resin.

Figure 14. Egg-shaped 12-

bladed finishing bur

completing the margin andshaping the lingual surface of

the composite restoration.

Figure 15. Flame-shapedfinishing point polishing the

lingual surface of the

composite restoration.

Intermediate finishing of the facial surface was accomplished with a cup-shaped rubber

finisher (Astropol, Ivoclar Vivadent) (Fig 13). The cup shape allows access to the gingival

facial margin and also contours the facial surface. If lobular facial form is desired in the

restoration, this can be accomplished once the facial surface has been smoothed by using a

disk-shaped rubberized abrasive. The lingual surface was finished with an egg-shaped

finishing bur (7406, SS White Burs) (Figure 14). The surface was then smoothed with a

flame-shaped point (Astropol, Ivoclar Vivadent) (Figure 15). The occlusion was then checked just prior to final polishing.

Figure 16a. Completedrestoration, facial view. Figure 16b. Aestheticalignment has been achieved



with direct composite resin

bonding.

The final polish was accomplished with a composite resin polishing paste (Extra Smooth

Composite Polishing Paste, Den-Mat) on a foam cup attached to a screw-in metal mandrel

(Luminescence, Premier Dental Products). Either a foam cup polisher or felt-covered disk will bring the polishing paste in contact with the anatomic areas created on the facial and

lingual surfaces. Another technique for attaining a smooth, high luster is using the finest grit

aluminum oxide disk available or the finest grit of rubber polishing point. Using the finest

abrasive disk or rubber point at greater than 18,000 rpm creates a highly lustrous surface.

This is because of both the polishing effect of the disk and heating of the resin surface; a

glassy appearance is the result. Interproxmal areas can be further polished with small-width

gapped fine abrasive finishing strips or composite resin polishing paste on a Lamineer plastic

polishing tip on a reciprocating handpiece. The final result is seen in Figures 16a and 16b.

DISCUSSION

The clinical success of finishing and polishing techniques can best be observed over time.

While the current generation of composite resins are highly polishable, highly polished

surfaces of resin-rich microfills are still prone to staining.25 The staining of composite resin

surfaces is directly related to patient variables, including diet (coffee, tea, wine, etc), as well

as other habits (smoking, spit tobacco, and the use of alcohol-containing mouthrinses). The

stain

polishing of anterior composite resin restorations

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