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Direct Posterior Composite Restoration

I. Fissure sealant as 1st choice before posterior composite restorations:

Pits and fissures typically result from an incomplete coalescence of enameland are particularly prone to caries, by using a low-viscosity fluid resin,

these areas can be sealed following acid etching of the walls of the pits /

fissures and a few millimeters of surface enamel bordering these faults.

Steps in application of sealant

Fissure in occlusal surface of mandibular molar with area isolated by rubber dam

Cleaning surface with pumice and bristle brush

Sealant inserted and finished

Brush

Pumice


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Sealants are most effective when they are applied in children to the pits andfissures of permanent posterior teeth immediately upon eruption of the clinical

crowns, Adults also can benefit from the use of sealants. Recent clinical studies shown that sealants can be applied even over small

cavitated lesions with no subsequent progression of caries. A recent bitewing radiograph should be made and evaluated prior to sealant

placement to ensure that no caries is evident that penetrates pulpal of the

dentino enamel junction (DEJ).

Typical failures of early composite restorations of occlusal and proximal surfaces

II. Limiting factors to provide " ideal dentistry: Patient preferences. Operator skill. Laboratory support.

Economic considerations. Esthetics.

III. Amalgam Composite replacement ethics:The American Dental Association 139th annual session, October 2000 (San

Francisco) Considered the indiscriminate replacement of amalgam restorations on the

basis of alleged toxicity with any other materials as unethical and irrational conduct

Occlusal wear with loss of centric stops incentral fosse

Color changes no proximal contacts andmarginal leakage


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IV. Newer composite formulations posses the general composition featuresand improved properties:

Raidopaque filers Smaller size of primary filer particles and the inclusion of dispersed

microfiller and even nanofillers.

Increased amounts of filler and a corresponding decrease in the resinmatrix.

Greater strength and stiffness. Reduced porosity. Reduced water sorption. Compatibility with new enamel / dentin bonding agents. Polymerization by visible light and reduce shrinkage. Ormocers are organically modified ceramics as new category to reduce the

organic fraction (BISGMA or UDMA) with an organosilane to get less

shrinkage and high mechanical properties.

Universal nanofilled composite were recently introduced for both anteriorand posterior restoration having very small filler particles that provide

greater wear resistance less marginal ditching, bulk fracture and better

color matching.

V. In fact the ADA Council of Dental Materials, Instruments and Equipmenthas given:

Acceptance status to several compositematerials for limited use in conservative

Classes I and II preparations in the absence ofsignificant occlusal stress.

However, ADA hasnot yet recognized any composite material as an amalgam

substitute.VI. Advantages:Advantages of bonded direct composite restoration (versus dental amalgam) for class

I, II & VI cavity preparation are as follows:

Esthetics. Conservation of tooth structure (no extension for prevention). Improved resistance to microleakage. Strengthening of remaining tooth structure.


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Low thermal conductivity. Completion in one appointment. Economic, less extensive compared to gold or porcelain restorations. No corrosion.

VII. Disadvantages:The following features of present direct posterior (Class I, II & VI) composites are

considered disadvantages (Compared with dental amalgam).

Very technique sensitive. Higher coefficient of thermal expansion than tooth structure. Low modulus of elasticity. Biocompatibility of some components unknown. Limited wear resistance in high stress areas.

VIII. Indications: Classes I and II cavities that can be appropriately Isolated and where some

centric contact(s) on tooth structure is (are) present.

Class V defects:o Hypoplasia and hypocalcification.o Carious lesion that is cavitated.o Abrasion and erosion.

Class VI cavities (faulty pits on selected occlusal cusps. Veneers for metal restorations. Repair of Fractured areas (tooth and or restorations). Restoration of a weakened tooth that can be reinforced by bonded

composite.IX. Contraindications:Composite materials generally are not recommended for direct posterior (Classes I, II

and VI) restorations under the following conditions.

The operating site cannot be appropriately isolated. All occlusal contacts will be in composite materials. Heavy occlusal stresses. Deep subgingival areas that is difficult to prepare or restore.


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X. Case selection: Amalgam and \ or gold posterior restorations provide an excellent service

for maPOSTERIOR

COMPOSITE RESINS A CURRENT ASSESSMENTHISTORY The use of posterior composite resins has been increasing for some time du

e topatients expectations

for esthetics and the lingering concern over mercury toxicity despite decades of formal proceedings on

the safety of dental amalgams that produced no sound scientific evidence of chronic toxicity in humans.

The quest for composite resins with sufficient strength and durability for posterior placement actually began nearly four decades ago, shortly after this class of materials was introduced to the dental profession as an extraordinarily successful alternative to silicate cements and direct filling resins. 1,2 Earlier materials showed relatively high rates of wear and secondary caries after a couple of years. 3,4 Figure 1 shows a cast of an earlier composite resin in tooth Figure 1

number 19 after two years. The occlusal wear along the margins is

apparent and measured approximately 400 microns. For the most part, these problems have been overcome due to evolutionary

advances in composite

resintechnology that included improved adhesion to dentin resulting in less mic

roleakage and

secondary caries development, a reduction in the size of inorganic filler particles resulting in less wear,

and visible light curing resulting in improved adaptation due to an unlimited working time as well as


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increased physical properties due to the elimination of voids incorporatedduring the mixing process.

ADVANTAGES The advantages posterior composite resin restorations offer

over dental amalgam are many:

Esthetics Most modern day composites are made available in numerous shades and s

everal variations in opacity

making possible excellent optical matches to tooth structure. The figures below (series courtesy Dr. Jeff

Blank) show a commonly used composite layering technique that can result in a high level of esthetics

when restoring posterior teeth. Figure 1. Cavity preparation

Figure 2. Flowable composite liner placed

Figure 3. Body layer placed up to DEJ Figure 4. Enamel layer placedfinished restoration

(2)Conservative Cavity Preparations A major benefit to using composite resins is the ability to prepare very con

servative cavity preparations.

When coupled with the strong bonds that can be formed with enamel and dentin, the result is less

weakening of tooth structure. There is usually no need for undercuts or extending cavity preparations

into self cleansing areas. Line angles are rounded and occlusal bevels are often not necessary. Figures 5

and 6 show an array of conservative cavities prepared to receive compositeresin restorations.

Figure 5 Figure 6 Increased Wear Resistance At a recent meeting of the International Association of Dental Research, da

ta were presented on a

packable posterior composite resin, SureFil


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High Density Posterior Restorative, DENTSPLY/Caulk, Milford, DE, showing mean marginal wear of only 142 microns after ten y

ears.

5 Considering this is less than wear measurements recorded for posterior enamel cusps, 6,7 it is apparent that contemporary composite resins matrerials can withstand the challenges posed in the poste

rior region of the mouth.

Reparability It has been shown that composite resin can bond to previously cured mater

ial, even after the oxygen

inhibition layer is removed, if the cured surface is first etched with phosphoric acid and then coated with

a chemically compatible bonding agent. 8 Lower Coefficient of Thermal Conductivity Teeth often become more sensitive to temperature fluctuations following o

perative procedures, and

restorative materials capable of rapidly conducting heat can only add to theproblem. Dental amalgam is

more than 30 times more conductive than dentin and gold is approximately500 times more

conductive; 9 therefore insulating bases are required when these materials are used in de

eper

restorations. While the minimal thickness of an insulating material has notbeen specified, anything less

than 0.5 mm would be considered of little help. 10 Filled resin materials are not good conductors of heat and in fact offer greater insulation than dental enamel,


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11 a desirable property that obviates the need for insulating bases. (3)Lower Incidence of Cusp Fractures? Numerous statements and implications have been made that composite resi

n restorations in posterior

teeth are less likely to be associated with fracturing of remaining cusps because they can be bonded so

well to tooth structure. The argument makes sense from the standpoint ofmaterial science, however, it

is not well supported with evidence. One study that observed 10,869 posterior teeth with amalgam or

composite resin restorations in 1,902 patients found no significant difference in the prevalence of cusp fractures between the two restorative materials. 12 There was a higher prevalence of cusp fractures in teeth with more than one surface restored and in older individuals but these were independent of the specific restorative material used. Figure 7. Fractured DB cusp #3 (Courtesy Dr. Jeff Blank) DISADVANTAGES Despite the many advantages offered by composite resins

and the vast improvements that have been

made in the properties of these materials over the past three plus decades, issues remain with their use

in the posterior region of the mouth, particularly for larger restorations. In1998 the American Dental

Association (ADA) issued a position statement on posterior resinbased composites that in general

supported theiruse, but not in teeth with heavy occlusal stress, in sites that cannot be isolat

ed or in


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patients who are allergic or sensitive to resinbased composite materials. 13 While a more recent position statement has not been published, the ADA did host a panel discussion

on posterior composite resins,

the proceedings of which appeared in the summer, 2006 issue of the ADAProfessional Products

Review. 14 The panelists noted that while the reports on the performance of posterior

composites have

generally been favorable, concern remains regarding use of the material inlarge restorations and the

durability of the bond to tooth structure since bonds have been shown in the laboratory to deteriorate

over time. It was further suggested in the panel discussion that posterior composite resins not be placed

in situations where good isolation is not possible, in patients with a high caries rate and/or poor oral

hygiene or in patients who clench or brux their teeth. Some disadvantages associated with the placement of composite resin rest

orations in the posterior

region of the mouth are as follows: Technique Sensitivity It has long been recognized that placing posterior composites resins is a m

ore demanding clinical

procedure compared to dental amalgam and may require twice the time forcompletion, particularly in

multisurface restorations. 15 Adequate light curing is essential for maximal physical properties, and incremental placement is necessary due to polymerization shrinkage stress

and depth of cure


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limitations. Obtaining proper anatomic form and marginal adaptation is more difficult with composite

resins due to their plastic consistency compared to the carving characteristics associated with dental

amalgam. Isolation becomes more critical when using composite resins than with dental amalgams or

glass ionomer cements since moisture contamination during the polymerization process can result in

reduced physical properties. (4)Obtaining proximal contact is also more difficult since even the heavies

t bodied composite resin

formulations have difficulty holding an extended matrix band in position, and specialized matrix systems

are normally required (Figure 8). Perhaps the greatest source of technique sensitivity in using composite resins is the need to bond to enamel and dentin. Modern day adhesives can bond adequately to both hard tissues even though they vary considerably in the number of steps involved, the type of solvent used and, in the case of selfetch adhesives, the pH value which can greatly influence the Figure 8. Sectional matrix in place (Courtesy Dr. Mark Latta) aggressiveness of the etching pattern. Most of the documented clinical trial

s on adhesives have been in

noncarious cervical erosion lesions since their nonretentive nature presents a formidable clinical

challenge to the strength and durability of an adhesive bond. These trials have shown good results with

both etchandrinse and selfetch adhesives, but the most consistent resultsseem to be associated with

the threestep etchandrinse systems and the twostep selfadhesive sytems.


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16 Nonantimicrobial Unlike dental amalgam, composite resins are unable to arrest the growth of

microorganisms, which

could result in a more rapid progression of recurrent or secondary caries. 15,20 Polymerization Shrinkage Stress The resin matrix of composite resin materials is composed of monomer mo

lecules that upon

polymerization convert to a polymer network wherein molecules are packed closer than in their free

state leading to bulk contraction. 17 If the resulting stress is greater than the bond strength to tooth structure, debonding could occur leading to marginal gap formation and irr

itation of the pulp due to

microbial colonization. 18 The extent of shrinkage and the resulting stress will depend upon the dyna

mics

of the polymerization reaction and the level of inorganic filler loading. Atthe clinical level, the degree of

stress placed on restorative margins is most influenced by the bulk of material being cured and the

configuration of the cavity into which the material is placed. The potentialfor a given cavity

configuration to cause stress at the margins of a restoration is known as theC factor and is calculated

very simply by dividing the number of bonded internal cavity surfaces by the number of nonbonded

surfaces. Below are shown the C factors for the various cavity classes (Courtesy Dr. Jeff Blank).

Class IV C= 0.5 Class III C= 1.0 Class I C= 5.0 Class II C= 2.0 (5)


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Class IV C=0.5 Class III C=1.0 Class I C=5.0Class II C=2.0Little clinical evidence exists to support a relationship betwe

en negative outcomes and polymerization

shrinkage stress;however, direct effects relative to bond stability can be shown in the labora

tory. It is

therefore prudent to at least bear in mind that shrinkage stress is likely an undesirable property for a

restorative material and practical steps that could minimize shrinkage stress should be considered. Such

steps include vertical rather than horizontal layering of composite resins and avoiding the placement of

bulk amounts of the material prior to light curing. POSTERIOR RESIN COMPOSITE FAILURE AND CAUSES Since composite resins were first considered as a potential replacement for

dental amalgam, questions

have been raised as to their suitability for such a critical role in dentistry. There are many reports

comparing the success rates of the two materials, and by and large composite resins have shown

acceptable performance even if not quite to the level of dental amalgam. Matching the efficiency of

dental amalgam as a public health measure is indeed beyond the reach ofmost restorative materials.

Table 1 shows the results of one comprehensive study that followed over 1700 posterior restorations for

a seven year period. Half of the patients received composite resin restorations while the other half

received amalgam. TABLE 1 MEAN ANNUAL SURVIVAL RATES OF COMPOSITES AND AMAL

GAMS

AFTER SEVEN YEARS (%) CHARACTERISTIC AMALGAM COMPOSITE


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TOOTH TYPE Premolar Molar 94.5 94.4 85.7 85.5 RESTORED SURFACES 1 2 3 4 or more 98.8 90.5 88.5 81.8 93.6 80.6 66.2 50.0 SIZE Small Medium Large 98.9 93.3 89.5 93.6 84.9 74.3 ALL 94.4 85.5 Adapted from Bernardo M et al 19


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As evident from the table, amalgam restorations did demonstrate fewer failures than composite resins

over the seven year period, particularly in restorations with three or more surfaces where composite

resins experienced a 50% failure rate in the largest restorations. This studyalso reported that the main

reason for restoration failures in both groups was secondary caries.However, the proportion of failures

due to secondary caries was higher in the composite resin group (88%) compared with the

(6)amalgam group (66%).It has been reported that the most frequent sites for secondary caries are th

e

gingival margins of all classes of restorations. 20 This is not terribly surprising given the difficult access many of these areas present as well as the challenges posed by bonding to

dentin and cementum as

compared with enamel. While the main cause for failure of posterior composite resin restorations a

ppears to be secondary

caries in the area of the gingival margin, the specific reasons for caries development are far less clear.

Certainly a low level of oral hygiene is considered by many as causative, yet the evidence is scant. It is

known that the replacement rate for posterior composite resins is higher inadolescents compared with

adults, perhaps owing to poorer oral hygiene and higher sugar intake in theyounger cohort. The

technique sensitivity of composite resin placement and associated bondingprocedures have been

thought to contribute to a reduced survival rate compared with amalgam, but evidence here is also


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lacking. One study had Class II restorations placed in teeth destined for extraction, following which the

restorations were observed on radiographs and under scanning electron microscopy.

21 It was reported that only 27% of gingival margins were free of defects, a finding that woul

d support the technique

sensitivity involved with placing composite resins in posterior teeth and perhaps also the higher risk

these areas face with respect to secondary caries. Surprisingly, the study also found that none of the

following variables had an effect on the quality of gingival margins: Experience level of the operator Horizontal versus vertical layering of restorations

Type of adhesive; onestep etchandrinse, twostep etchandrinse or two

step selfetch

While this study highlighted the gingival margin as an area that should receive focused attention, it did

not suggest that experience, layering technique or adhesive selection would help remedy the observed

defects.Another study that evaluated the longevity of posterior resin composite res

torations cast a

shadow of doubt over the insistence on the part of some that rubber dam isolation is essential for a

successful restoration since it did not result in significantly higher survivalrates than isolation by cotton

rolls. 22 LINERS


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Some comments regarding the use of liners and flowable composites in particular beneath posterior

composite resin restorations are in order since a recent survey 23 indicated that 90% of dentists have used a flowable composite in the past twelve months, and that 82% of flow

able users apply them as

liners. The use of flowable composite liners has been claimed to increasemarginal adaptation in the

gingival marginal area of Class II restorations thereby reducing microleakage. It has also been claimed to

mollify polymerization shrinkage stress on the part of the composite resindue the more more elastic

nature of flowable composite resins. Recent work has shown that the use of a flowable liner showed

fewer voids at the interface of the restoration and tooth structure in the cervical area of Class II

restorations when compared with bonding agent and resin composite alone.

24 The study also showed that thicker (2mm) flowable precured liners showed more marginal leakag

e when compared with

thinner (0.51mm) liners. This finding would obviously refute the notion that flowable liners could

counteract the effects of polymerization shrinkage stress from the composite resin. Finally, this study

showed that a lining technique originally presented by Jackson and Morgan

25 involving placement of a packable composite over a thin uncured flowable liner resulted in the best

marginal sealing of all groups


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tested. (7)REFERENCES 1. Phillips RW, Avery DR, Mehra R, Swartz MI, McCune J. Observations

on a composite resin for Class II

restorations: twoyear report. J Prosthet Dent Aug 1972;26:6877. 2. Phillips RW, Avery DR, Mehra R, Swartz MI, Mc Cune J. Observations

on a composite resin for Class II

restorations:threeyear report. J Prosthet Dent Dec 1973;30:8917. 3. Eames WB, Strain JD, Weitmann RT. Williams AK. Clinical compariso

n of composite, amalgam and

silicate restorations. JADA 1974;89(5):1117 4. Leinfelder KF, Sluder TB, Santos JFF, Wall JT. Fiveyear clinical evalu

ation of anterior and posterior

restorations of composite resin. Oper Dent 1980;5(2):5765 5.Wilder AD, Bayne SC, Heymann H, Perdigao, J, Swift EJ. 10year clinic

al performance of packable

posterior composite. 2008 IADR Abstract #0238. 6. Molnar S, McKee JK, Molnar IM, Pryzbeck TR. Tooth wear rates amon

g contemporary Australian

Aborigines. J Dent Res 1983;62:5625. 7. Lambrechts P, Braem M, VuylstekeWauters M, Vanherle G. Quantitati

ve I vivo wear of human

enamel. J Dent Res Dec 1989;68(12):17524. 8. Blank JT, Latta MA. Bond strength of composite to composite simulatin

g clinical layering. 2003 IADR

Abstract #2003. 9. Craig RG, Peyton FA. Thermal conductivity of tooth structure, dental ce

ments and amalgam. J Dent

Res MayJune 1961;40:4118. 10. Jeffrey IWM. The relationship of lining thickness and thermal insulatin

g efficiency. J Oral Rehab

1984;11:42939.


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11. Saiho M et al. Thermal properties of dental materials. Part 10. Crown and bridge resins containing

high concentrations of filler. J Japan Soc Dent Mat Dev 2000;19(5):4417. 12. Wahl MJ, Schmitt MM, Overton DA, Gordon KM. Prevalence of cusp

fractures in teeth with amalgam

and with resinbased composite. JADA August 2004;135:112732. 13. ADA Council on Scientific Affairs; ADA Council on Dental Benefit P

orgrams. Statement on posterior

resinbased composites. JADA Nov 1998;129:16278. 14. Hilton TJ, Ferracane J, Liebenberg W, Sarrett DC, Swift EJ. Posterior

composites: expert panel

discussion. Summer 2006;1(1). 15. Leinfelder KF. Posterior composite resins: the materials and their perfo

rmance. JADA May

1995;126:66376. 16. De Munck J, Van Landuyt K, Peumans M, Poitevin A, Lambrechts P,

Braem M, Van Meerbeek B. J

Dent Res 2005;84(2):11832. 17. Davidson CL, Feilzer AJ. Polymerization shrinkage and polymerizatio

n shrinkage stress in polymer

based restoratives. Journal of Dentistry 1997;25(6):43540. 18. Roulet JF. Benefits and disadvantages of toothcoulored alternatives to

amalgam. Journal of

Dentistry 1997;25(6):45973. 19. Bernardo M, Luis H, Martin MD, Leroux BG, Rue T, Leito J, De Rou

en TA. Survival and reasons for

failure of amalgam versus composite posterior restorations placed in a randomized clinical trial. JADA

June 2007;138:77583. 20. Mjr IA, Clinical diagnosis of recurrent caries. JADA Oct 2005;136:14

2633.

21. Opdam NJM, Roeters FJM, Feilzer AJ, Smale I. A radiographic and scanning electron microscopic


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study of approximal margins of Class II resin composite restorations placed in vivo. Journal of Dentistry

1998;26(4):31927. (8)22.Brunthaler A, Knig F, Lucas T, Sperr W, Schedle A. Longevity of

direct resin composite restoration in

posterior teeth. 2003 Clin Oral Invest;7:6370. 23. Council on Scientific Affairs of the American Dental Association. Spri

ng 2009;4(2).

24. Chuang SF, Jin YT, Chang CH, Shieh DB. Influence of flowable composite lining thickness on Class II

composite restorations. Operative Dentistry 2004;29(3):3018. 25. Jackson RD, Morgan MM. The new posterior resins and a simplified pl

acement technique. JADA

March 2000;131(3):37583. (9)ny years, whereas posterior composite restoration may not serve as

long. Amalgam and \ or gold posterior restorations have adequate strength and

wear resistance to support occlusion in high stress areas, whereas wear of

posterior composite restoration may be greater. It is important that the occlusion be, evaluated preoperatively to determine

the bite relationship and type of occlusal function.

To maintain proper vertical dimension, at least one centric holding contactshould be located on sound tooth structure or on the same type of

restorative material that has wear rate approximately that of tooth

structure.

Articulating paper

point

Occlusal centric stops


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During evaluation of occlusion centric stops and functional patterns are marked

articulating with paper. Classes I posterior restorations could be placed in selected

areas of these premolar maxillary teeth.

XI. Cavity preparation designs:A. Conventional Preparation Design:

These boxlike cavity designs have slightly converging (toward theocclusal) external walls, basically flat floors and undercuts in dentin for

retention form. Although the conventional type of preparation can be used withposterior composites for Classes I, II or VI cavities, it is usually not

employed in its entirety because of the benefits of beveling most enamel

walls.


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Conventional cavity preparation for amalgam or composite restorations

Moderate size class I cavity preparation

Large class II cavity preparation

B. Beveled conventional preparation design: The Incorporation of an enamel cavosurface bevel in preparations forcomposite is recommended, because it provides more surface area for bonding

and it allows for the more preferred end on etching of the enamel rods.

These features increase retention, reduce leakage and provide greaterpotential for strengthening the remaining tooth structure. The bevel is prepared with a coarse, flame shaped diamond instrument,approximately 0.5 mm wide, and at an angle of approximately 45 to the

external enamel surface.

Beveling is particularly beneficial when placed along facial and lingualwalls of proximal box because the enamel rods run parallel to these cavity

walls:

It increases the surface area along the end of the enamel rods,resulting in improved retention and resistance to leakage.


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It is most frequently used for restoration of class I & VI cavities,when there is a need for increased resistance form to resist occlusal

forces.

C. Modified preparation design: Typically dictated by the extent of the lesion or defect, conserving as muchintact tooth structure as possible, and in some rare instances the preparation

can be restricted entirely to enamel.

Modified preparations are characterized by: The conservative removal of only thedefective or carious tooth

structure. The establishment of a beveled configuration on all enamel

cavosurface margins.

Extensive modified designs for Classes I and II cavities can incorporateunique preparation features such as: Reverse Bevels, Secondary flares and

Brace-Type Skirting at the axial transitional tooth corners to enhance

retention and resistance form. Large preparations of this type should not beconsidered routine and are contraindicated except

in specific compromise situations.

Modified Class I cavity preparation for posterior

composite restorations

(A) Marginal configuration for

beveled conventional

preparation.

(B) Occlusal bevel are less

beneficial due to enamel rod

orientation.

Some undermined

enamel is maintained

Extension strengthen

remaining toothstructure Extensive cavitypreparation.


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XII. Preventive Resin Restoration (PRR) or class one conservative compositerestoration:

This design allows for restoration of the lesion or defects with minimal removal oftooth structure and often may be combined with the use of composite or sealant to

seal radiating non-carious fissures or pits that are at high risk for subsequent caries

activity. It is referred to as a conservative composite restoration or preventive risin

restoration PRR.

An accurate diagnosis is essential prior to restoring the occlusal surface of aposterior tooth. The critical factor in this clinical assessment is whether or not the

suspicious pit or fissure is cavitated, therefore requiring restorative intervention. After deciding that cavitations has occurred, it usually must be determinedwhether to use amalgam or composite; important factors related to this decision

include: Ability to isolate the tooth \ teeth. Occlusal relationship. Esthetics. Operator ability. Environmental amalgam restriction.

Advantages of preventive resin restoration (PRR) over amalgam are: Conserving tooth structure. Enhancing esthetics. Bonding tooth structure together. Sealing the prepared tooth structure. Including other suspicious areas on the occlusal surface with either the

composite restorative material or a sealant material.

When caries is limited to enamel, there is no need to prepare into dentin as isnecessary for amalgam restoration.

Small cavities could be restored with flowable composite that may also act asa fissure sealant or composite resin followed by fissure sealants to seal the

adjacent fissures. This procedure is considered less traumatic to the patient and

minimally invasive to the tooth structure.


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XIII. Simple proximal box preparation:1) It's used to restore a small proximal lesion without either occlusal

fissure or previously inserted occlusal restoration. It's limited to teeth

with narrow interproximal contact.

2) The outline could have rounded margins as in resinous material orcould be in the form of definite walls as in case of amalgam

restorations.

3) It's mainly used whenever there's a need to avoid cutting into soundocclusal surfaces.

4) Buccal and lingual walls of the boxes should be almost facing eachother to maximize retention. It's done without an occlusal step.

5) To compensate to the lack of occlusal portion that allows retentions,proximal retentive groves on the expense of facial and lingual walls

having 0.5 mm at the gingival point angles and taper to 0.3 mm at the

occluso surface are done.

6) Using amalgam or resin composite according to cavity design.

XIV. Slot preparation:1) Used in old patient who have gingival rescission

and often experience cavities on the proximal

exposed cementum on the root surfaces that is

gingival to the contact area. Or whenever wide

embrasures are encountered that allow easy access to the proximal

lesion sparing the marginal ridges and the occlusal surfaces.

2) The approach to perform this design is buccally or lingually in theform of a slot.

Pear shaped proximal

box prepared for resin

restoration or GIC.

Proximal box prepared

for amalgam.


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3) Offers better esthetics, does not alter occlusal relationships, maypreserve a natural proximal contact and enjoys greater patient

acceptability than traditional approach.

4) The occlusal and gingival walls should be perpendicular to the long Ina cavity with buccal approach, the buccal wall must flare suffiently to

allow access and visibility while the lingual wall should face buccally

as much as the caries extension allows resisting the condensation

forces.

5) Two retentive grooves could be placed along the occluso-axial andgingivo-axial line angles if retention is required for non-bonded

restoration.

6) Could be restored using amalgam, resin composite or glassionommerand its modifications.

XV. Tunnel preparation:1) Also termed internal fosse, internal

oblique preparation, internal occlusal

diagnonal preparation or simply internal

preparation.

2) The tunnel approach for a proximallesion preparation allow preservation of

the marginal ridge; access could be

directly on the lesion by trepanning the

occlusal enamel in the fosse near the

marginal ridge keeping it untouched, a

diagonal inclination of the cutting tools

is then done to keep the occlusal marginal ridge without undermining

it.

3) Air abrasion has proven effectiveness lately in performing such adesign.

4) The decayed tissue is then removed with or without involvement of aproximal enamel .this is referred to, as 'partial tunnel' preparation

when this proximal enamel is left undisturbed as it's neither carious nor

cavitated but left supported by sound dentine.


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5) The 'total tunnel' preparation is that when the proximal enamel hasbeen perforated by the carious lesion and removed during the

preparation.

6) The most suitable restorative material used in conjunction with thismodality is the cavity has to be filled to the level of DEJ with GIC and

the rest is filled with composite. Other restoratives can also be used

with this technique like compemers, cement or any high resisting GIC.

7) Molars failed 5 times as often as premolars did. It's thus recommendedthat tunnel technique be used for premolars.

8) The tunnel preparation and restoration are still until now controversyas no firm data have been given to support its use unrestrictedly.

XVI. Ultra conservative cavity preparation:It is determined by the size and shape of the carious lesion rather than by cutting an

outline per sec. Conservative outline vary according to the tooth type, occlusal

pattern, oral hygiene and cares risk tests. The width of the cavity has decreased

enormously from 1/3 to 1/4 the inter cuspal distance to 1/8 to 1/6 of the inter cuspal

distance and sealing fissures and retentive grooves with fissure sealant.

XVII. Class II cavity preparations for moderate composite restoration:1. Even though the ADA has not endorsed composite:As a substitute for amalgam in posterior teeth, composite restorations in Classes I

and VI (as already presented) are excellent when done properly.

2. Composite may be used successfully in restoring class II cavities: When the potential to seal the tooth and strengthen the remaining toothstructure by bonding composite to the tooth, along with the obvious esthetic

benefits are taken in consideration.

Recall that a conservative beveled conventional cavity preparation isrecommended for most moderate Class II composite restorations.

3. Limiting factors for the use of composites in Class II applications are:i. The inability to isolate the area (the bond may be compromised),ii. Deep subgingival extensions (preparation, insertion, and bonding may be

compromised), and


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iii. Occlusal contact entirely on the composite (increased wear may occur).4. Early wedging: a wedge is placed interproximally before cavity preparations:

i. Separating the teeth to compensate later for the thickness of the matrixband.

ii. Depresses and protects the rubber dam and gingival tissue when theproximal area is prepared.

iii. The presence of the wedge during cavity preparation also is a guide tohelp prevent overextension of the gingival floor.


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Preoperative and postoperative views of moderate posterior compoAsite

restorations

Failing amalgam restorations are not in centric holding areas

Isolation with rubber dam, Cavity preparation with protective base in place

Initial appearance of compositerestorations

After 3 years of service. Occlusionis marked with articulating paper

Articulating paper mark

Failing amalgam

Rubber dam

Protective base


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5. Main variations in Class II cavity design for a composite restoration as opposed

to that for an amalgam:

i. The axial wall initial depth usually is limited to a depth of 0.2 mm intodentin. This means that the tip of the No. 245 bur would be cutting less

than one half in dentin and more than one half in enamel to be most

conservative. (The diameter of the bur's tip end is 0.8 mm). This

decreased pulpal depth of the axial wall allows greater conservation of

tooth structure since retention locks will not be used. The occlusal walls

are prepared to converge occlusally.

ii. Many areas of the enamel are unsupported by dentin, but not friable.This undermined enamel is not removed, it will be reinforced by etching

and bonding.

iii. Placing bevels on the occlusal and proximal cavosurface margins, ifaccess permit, with a coarse, flame-shaped diamond instrument. Recall

that bevels on the occlusal surface may be considered optional (if not

required for fissure treatment) due to enamel rod direction, especially in

areas of steep cuspal inclines. Also, beveling of the proximal box enamel

to cavosurface margins must be done judiciously.

iv. For placement of bevels it may necessitate undue extension, which maycause the operator to decide whether to reduce or eliminate the proximal

beveling.

XVIII. Extensive Classes I and II preparations for posterior composites: "Real world" dentistry sometimes necessitates esthetic treatmentalternatives that, while representing a clinical compromise, may provide a

needed service to the patient.

Large posterior composite restorations sometimes can be used as areasonable alternative when more permanent options are not possible or

realistic.

The patient must be informed of the possible limitations of these largeposterior composite restorations; primarily excessive wear and increased

recurrent caries potential.


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Most extensive Classes I and II composite restorations will utilize abeveled conventional cavity preparation design. Increased bevel widths may

assist in both the retention of the material and strengthening of the weakened

tooth.

A) Class I extensive modified preparations: Because first molars erupt at an early age, they are sometimes

neglected and extensive caries may develop. When infected dentin is

removed, a severely weakened tooth with unsupported cusps may

remain.

In an effort to splint the weakened facial and lingual cuspal elementstogether, facial and lingual extensions are made with a coarse, rounded-

end diamond instrument.

The depth should be at least 1mm into enamel as the extension crosses thecusp ridge and approximately 0.5 mm deep in the facial and/or lingual

enamel.

Some unsupported, but not friable, enamel may be left because it will bereinforced by etching and bonding. When properly etched and restored, the

composite material acts as a splint to lock the tooth together for resistance

to fracture under masticatory forces.


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Favorable occlusion permitting extensive modified Class I cavity

preparations (mandibular teeth) for composite restorations

Rubber dam isolation of teeth with

fault amal am restorations.

Faulty amalgam

Secondary caries

Existing amalgam restorations

removed revealin secondar caries.

Undermined cusps

Facial and lingual cusps undermined

b removal of infected dentin

Bases inserted and preparation

com leted

Base

Model illustrating extension

and bevels prepared with

diamond instrument to

strengthen the tooth by the

splinting action of bonded

com osite restoration.


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B.Class II extensive modified cavity preparations:

Esthetics and economics were factors in the decision to replace old faultyamalgam with a composite restoration.

A coarse, flame-shaped diamond instrument was used to reduce theseverely undermined enamel of the lingual cusp approximately 1.5mm and

place a reverse bevel with a chamfered margin on the lingual surface.

The same instrument was used to reduce the facial cusp 0.75 mm andplaced slight counter bevel on the facial cusp.

Skirts were placed on all of the axioproximal walls except the mesiofacial,where a secondary flare was used.

This wraparound design in the enamel allows the bonded compositerestoration to brace the tooth to resist fracture.

In this wraparound design note: Reverse bevel lingual cusp. Counter bevel facial cusp. Skirt bevel all axioproximal walls. Secondary flare mesiofacial wall.


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direct posterior composite 1

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