Composites

COMPOSITE

INTRODUCTION The esthetic quality of a restoration may be as important as mental health of the patient as the biologic and technical qualities of the restoration are to his physical and dental health --(Skinner-1959)

The introduction of Acid_etch technique by Micheal Buonocore in 1955 and Composite resin later in 1962 by R.L. Bowen are the two major advances that make the restorative dentistry more conservative and esthetic concern .

Today, the Composite resin enjoy universal clinical application. They can be used in almost all type and size of restoration. The composite restoration can be accomplished with minimal loss of tooth structure, little or no discomfort, relatively short operating time and modest of expenses to the patients when compared to esthetic ceramic restorations. Composite restoration in comparision to other direct tooth coloured restoration is relatively insoluble, insensitive to dehydration and easy to manipulation

However, Composite resins do have some technical limitations that make the restorative procedure more complex and challenging in some clinical situations. Bonding of Composite resin is very technique sensitive. Failure in bonding can result due to numbers of causes including trauma , improper tooth preparation , mishandling and improper use of the materials.

The patient co-operation is of utmost important in long term success of any restoration .So, it is in part of the restorative procedure to educate and motivate the patient to practice preventive measures, including proper diet, good oral hygiene and maintenance recall visits

The choice of the material to restore the decayed teeth due to carious lesion or the other defects continues to be controversial in the field of restorative dentistry. The restorative dentist is the best judge to select the material of choice after proper discussion with the patient considering all physical, dental, and socioeconomic factors.

The restorative dentist is also responsible for performing and accomplishing each operative procedure with meticulous care and proper attention to the technical details to gain the maximum benefit of the materials properties.

The purpose of the seminar is to highlight the technical details that are to be considered while performing Composite restorative procedures to get clinically long term successful restorations in varieties of clinical situations.

CLASSIFICATION OF COMPOSITE RESTORATIONS

The composite restorations can be categorized as:

1) Direct composite restoration- directly bonded to enamel and dentin.2) Indirect composite restoration- bonded to enamel or dentin with the help of luting or cementing medium.

3) Semi direct restoration- needs intra-oral as well as extra oral steps to produce luted chair-side restorations

GENERAL CONSIDERATIONS FOR DIRECT COMPOSITE RESTORATION

In selecting direct restorative material, practitioners usually choose between Composite and Amalgam. Following are some of the general factors that are to be comparatively analyzed before going to perform a Composite restoration:

1) Isolation factors: For composite restoration to be successful , it must be appropriately bonded to tooth structures (both enamel and dentin) . Bonding to tooth structure requires an environment isolated from contamination by oral fluids or other contaminants; such contamination prohibit bond development.

Therefore the ability to isolate the operating area is a major factors in selecting a Composite material for a restoration. If operating area can be isolated, a bonding procedure can be successfully done ; otherwise a non-bonded Amalgam may be the material of choice. If bonding is possible the practitioner has to consider Composite, bonded Amalgam, or a Glass ionomer restoration, as well as bonding of an indirect restoration with an appropriate cementing agent, and analyze considering the other factors:

2) Occlusal factor: composite materials exhibit less wear resistance than amalgam; however, studies indicate that with contemporary composites the wear resistance is not substantially different from that of Amalgam.13 For patient with either heavy occlusion, bruxism, or restorations that provide all of a tooths occlusal contacts, Amalgam rather than the Composite is the material of choice. 3) Operators ability and commitment factors: The restorative procedure for composite restorations is relatively easy. However, the operator must pay greater attention to the technical details to successfully accomplish a composite restoration. This requires both technical ability and knowledge of the materials used and limitations.

Besides, patient's expectation and the socio-economic factors are also to be considered.

INDICATIONS OF DIRECT COMPOSITE RESTORATION: The American Dental Association1 has indicated the appropriateness of composite for use asa. Pit and fissure sealant and preventive composite restoration

b. Moderate size class I, II, III, IV and V restorations

c. Restorations of aesthetic important areas

d. Partial veneers

e. Full veneers

f. Tooth coloured modificationsg. Diastema closuresh. Restorations in patients allergic or sensitive to metals.

CONTRAINDICATIONS OF COMPOSITE RESTORATION:The primary contraindication for the use of composite as a restorative material relate to the factors as already mentioned like isolation, occlusion and operator factors.Composite restorations extension on the root surface may exhibit gap formation at the junctions of the composite and the root. Any restoration that extends on to the root surface may result in less than ideal marginal integrity.

ADVANTAGE VS DISADVANTAGEAdvantage:1. aesthetic

2. conservation of tooth structure

3. less complex when preparing the tooth.

4. insulative, having low thermal conductivity

5. used almost universally.

6. bonded to tooth structure resulting in good retention, low microleakage, minimal interfacial staining, and increased strength of remaining tooth structure.

7. repairable.Disadvantage:

1. may have a gap formation usually occurring on the root surface as a result of process of polymerization shrinkage.

2. more difficult, time consuming and costly compared to amalgam restoration because :

a. tooth treatment usually requires multiple steps

b. insertion is more difficult.

c. Establishing proximal contact, axial contours, embrasures and occlusal contacts may be more difficult.

d. Finishing and polishing procedures are more difficult.

3. are more technique sensitive because the operating site must be properly isolated and the placement of etchant, primer, and adhesive on the tooth structure is very demanding of proper technique.

4. may exhibit greater occlusal wear in area of high occlusal stresses.

5. have a higher linear coefficient of thermal expansion resulting in potential marginal percolation if an inadequate bonding technique is utilized.

CLNICAL CONSIDERATIONSPreoperative considerations:

It is necessary that the complete examination, diagnosis and treatment plan be finalized before the patient is scheduled for operative appointments. A brief review of chart including medical factors, treatment plan and radiographs (preferably bite wing x-ray) should precede the restorative procedures.

The restorative dentist should draw the attention to the following considerations before starting the tooth preparations:

Local anesthesia.- may be required for many operative procedures. Profound anesthesia contributes to a more pleasant and uninterrupted procedures and usually results in a marked reduction in salivation

Preparation of the Operating site:

It may be necessary to clean the operating site with slurry of pumice to remove plaque, pellicle and superficial stain. Calculus removal with appropriate instrument also may be needed. These steps create a site more receptive to bonding.

Shade selection: The shade of the tooth should be selected before the teeth are subjected to any prolonged drying, because dehydrated teeth become lighter in shade as a result in decrease in translucency. Most manufacturers provide shade guides for their specific materials. Good lighting is necessary when shade selection is made. Natural light is preferred for selection of shades

Isolating the Operating Field Goals of isolation

Moisture control: Moisture control refers to excluding sulcular fluid, saliva and gingival bleeding from the operative field. It also refers to preventing the handpiece spray and restorative debris from being swallowed or aspirated by the patient. The rubber dam, suction devices, and absorbents are varyingly effective in moisture control. Generally, the rubber dam is a recommended technique for moisture control.

However, Raskin et al19 and Fusayama8 have reported that achieving effective isolation; is more important than the specific technique utilized

Methods of isolationRubber dam isolation

In 1864, S.C. Barnum, a New York City dentist, introduced the rubber dam into dentistry. Use of the rubber dam ensures appropriate dryness of the teeth and improves the quality of clinical restorative dentistry2.

Advantages: are significant and become obvious as the operator gains proficiency , because of:

A dry, clean operating field

Improved access and visibility

Potentially improved properties of dental material

Protection of the patient and operator

Operative efficiency

Smales20 concludes that there is no difference between the use of the rubber dam and cotton roll isolation; each relates to restoration quality and survival. However, Christensen reports that use of a rubber dam increases both the quality and quantity of restorative services.

Disadvantages: Rubber dam usage is low among private practitioners. Time consumption and patient objection are the most frequently quoted disadvantages of the rubber dam. However, these concerns are reduced with the use of a simplified technique for application and removal. Usually the rubber dam can be placed in 3 to 5 minutes. 21

Certain oral conditions may preclude the use of the rubber dam:

Teeth that have not erupted sufficiently to support a retainer

Some third molars, and

Extremely mal positioned teeth

In addition, patients suffering from asthma may not tolerate the rubber dam if breathing through the nose is difficult. Also, there are rare instances when the patient cannot tolerate a rubber dam because of psychological reasons or latex allergy

Material and instruments:

Rubber dam material is available in 5(5 inch (12.5(12.5 cm) or 6(6 inch (15(15 cm) sheets. Sterile dam material is also available packaged as individual sheets. The thicknesses or weights available are thin (0.006 inch [0.15 mm], medium (0.008 inch [0.2 mm]) heavy (0.010 inch [0.25mm]), extra heavy (0.012 inch [0.30 mm]) and special heavy (0.014 inch [0.35mm]). Both light and dark dam material are available; but the dark color is preferred for contrast. Green and blue colors are also marketed.

The rubber dam holder (frame) The young holder is a U-shaped metal frame with small metal projections for securing the border of the rubber dam in positionPlacement of rubber dam: step by step technique

1:Testing and lubricating the proximal contacts

2: Punching the Holes

3: Lubricating the Dam

4: Selecting the Retainer

5: Testing the Retainers stability and Retention

6: Positioning the Dam over the Retainer

7: Applying the Napkin

8: Positioning the Napkin

9: Attaching the Frame

10: (Optional): Attaching the Neck strap

11: Passing the Dam through posterior contact

12: (Optional): Applying compound

13: Applying the Anterior Anchor (If needed)

14: Passing the Septa Through the contracts without tape

15: Passing the Septa through the contacts with Tape

16 (Optional): Technique for using Tape

17: Inverting the Dam interpoximally

18: Inverting the Dam Facio-lingually

19 (Optional): Using a saliva Ejector

20: Confirming a properly applied rubber dam

21: Checking for Access and Visibility

22: Inserting the Wedges

Removal of the rubber dam

1: Cutting the Septa

2: Removing the Retainer

3: Removing the Dam

4: Wiping the lips

5: Rinsing the mouth and massaging the tissue

6: Examining the dam

Cotton Roll isolation and cellulose Wafers: Absorbents are isolation alternatives when rubber dam application is impractical or impossible. In conjunction with; profound anesthesia, absorbents provide acceptable moisture control for most clinical procedures. Using a saliva ejector in conjunction with absorbents may further abate salivary flow. The assistant has the responsibility of keeping g dry cotton rolls in; the mouth. The assistant should change the cotton rolls when they become saturated.

Other isolation techniques:Throat Shields: When the rubber dam is not being used throat shields are indicated when there is danger of aspirating or swallowing small objects. This is particularly important when treating teeth in the maxillary arch. A gauze sponge (2 ( 2 inch [5 ( 5 cm]), unfolded and spread over the tongue and the posterior part of the mouth, is helpful in recovering small objects, such as an indirect restoration should it be dropped

High volume evacuators and saliva ejectors: High volume evacuators are preferred for suctioning water and debris from the mouth because saliva ejectors remove water slowly and have little capacity for picking up solids.. Mc Wherter(1957) showed that one type of evacuator would remove 1 pint (0.5 L) of water in 2 seconds, had a 75% to 95% pick of water air and would remove 100% of solids during cutting procedures.Retraction Cord: When the rubber dam is not used, is impractical, or is inappropriate, retraction cord, usually moistened with a non-caustic styptic may be placed in the gingival sulcus to control sulcular seepage and/or hemorrhage. Most brands of retraction cord are available with and without the vasoconstrictor epinephrine, which also acts to control sulcular fluids. A properly applied retraction cord improves access and visibility and helps prevent abrasion of gingival tissue during tooth preparation. Retraction cord may help restrict excess restorative material from entering the gingival sulcus and provide better access for contouring and finishing the restorative material

Mirror and evacuator Tip Retraction

Mouth props: A potential aid to restorative procedures on posterior teeth. A prop should establish and maintain suitable mouth opening thereby relieving the patients muscles of this task, which often produces fatigue and sometimes pain. Moreover, with the use of a prop, the patient is relieved of the responsibility of maintaining mouth opening, thereby permitting added relaxation.

Drugs: The use of drugs to control salivation is rarely indicated in restorative dentistry and is generally limited to atropine. It is important to remember that atropine is contraindicated for nursing mothers and patients with glaucoma

TOOTH PREPARATION FOR COMPOSITE RESTORATION:

The basic principle of tooth preparation must be followed for composite restoration. The tooth preparation should include:

Outline form: to remove all the caries, fault, defect or old restorative material (when necessary) in most conservative manner possible.

Retention form: a composite material must be retained within a tooth, but this primarily results from the micromechanical bonding of the composite to the roughened, etched, and primed enamel and dentin. In some instances a dentinal retention groove or enamel bevel may be prepared to enhance the retention form

Resistance form: which keeps the tooth strong and protects it from fracture, is primarily accomplished by the strength of the micromechanical bond but may be increased when necessary by usual resistance form features such as flat preparation floors, box like forms and floor prepared perpendicular to the occlusal surfaces.

Pulp protection: the pulp protection procedures are different for a composite restoration because the composite is bonded to the prepared tooth and the composite material is insulative, there is no need for any base under composite restorations. However the calcium hydroxide liner is still indicated when a pulp exposure (or a possible pulp exposure) occurs.

These objectives can be met by producing a tooth preparation form significantly different from that for an amalgam restoration:

Less outline extension

An axial and/or pulpal wall of varying depth

Incorporation of enamel bevel in some areas

Tooth preparation walls being rough

Use of a diamond stone to increase surface roughness

Design of the tooth preparation

The design of the tooth preparation to receive a composite restoration may vary depending on several factors. Theodore M. Roberson et al21 described mainly five types of cavity designs for composite restoration, which may some times be used in combination. They are:

Conventional

Beveled conventional,

Modified

Box only

Slot preparations designs.

Tooth preparation Class III composite restoration

When a proximal surface of an anterior tooth is to be restored and there is a choice between facial or lingual entry into the tooth, the lingual approach is preferable. A small carious lesion should be treated from the lingual approach unless such an approach would necessitate excessive cutting of tooth structure, such as in instances of irregular alignment of the teeth or facial positioning of the lesion.

The advantages of restoring the proximal lesion form the lingual approach include.

The facial enamel is conserved for enhanced esthetics

Some unsupported, but not friable, enamel may be left on the facial wall of the Class III or Class IV preparation.

Color matching of the composite is not as critical

Discoloration or deterioration of the restoration is less visible

The indication for a facial approach include

The carious lesion is positioned facially such that facial access would significantly conserve tooth structure

The teeth are irregularly aligned, making lingual access undesirable

Extensive Caries extend on to the facial surface

A faulty restoration that was originally place for facial approach needs to be replaced

When both the facial and lingual surfaces are involved, use the approach that provides the best access for instrumentation.

It is expeditious to prepare and restore approximating carious lesions or faulty restorations on adjacent teeth at the same appointment. Usually one of the preparations will be larger (more extended outline form) than the other. When the larger outline form is developed first, the second preparation usually can be more conservative because of the improved access provided by the larger preparation. The reverse order would be followed when the restorative material is inserted.

Conventional Class III Tooth preparation: The primary indication for this type of Class III preparation is for the restoration of root surfaces. In such a situation, the design of the preparation would be a combination of the modified or a beveled conventional preparation with a conventionally prepared root surface area.

When preparing the conventional portion, preparation is done using a No. , 1, or 2 round bur or diamond . The cavosurface margins exhibit a 90-degree cavosurface angle and provide butt joints between the tooth and the composite materials. Thus the external walls are prepared perpendicular to the root surface.

These walls must be prepared to a sufficient depth pulpally to provide for the following:

The axial wall depth (depth to axial line angles) usually will be approximately 0.75 mm into dentin, assuming no additional caries excavation is required.

Adequate removal of the caries, old restorative material, or fault

The placement of retention groves, if deemed necessary.

Facial approach: Once adequate access is achieved, remove all remaining infected dentin using round burs or small spoon excavators, or both. Remaining old restorative material on the axial wall should be removed if any of the following conditions are present

If the old material is amalgam and its color would negatively affect the color of the new restoration

There is radiographic evidence of caries under the old material

The tooth pulp was symptomatic pre-operatively

The periphery of the remaining restorative material is not intact

The use of the underlying dentin is necessary to effect a stronger bond for retention purposes

The boxlike design may be considered a part of retention form

Groove retention may be necessary in root surface preparations to better ensure that the restorative material is retained in tooth. A continuous retention groove can be prepare in the internal portion of the external walls using a No. round bur and/ or using hand cutting instruments

Beveled Conventional Class III Tooth Preparation:It is indicated primarily for replacing an existing defective restoration in the crown portion of the tooth. When restoring a large carious lesion for which the need for increased retention and / or resistance form is anticipated. The tooth preparation for the replacement restoration will have the same general form of the previous (old) tooth preparation.

Usually retention is obtained by bonding to the enamel and dentin and no groove retention is necessary. However, when replacing a large restoration or restoring a large Class III lesion, the operator may decide that retention form should be enhanced by placing groove (at gingival) and/or cove ( at incisal) retention features in additional to the bonded tooth structure.

The cavosurface bevel or flare is best prepared with either a flame shaped or round diamond instrument, resulting in an angle approximately 45 degrees to the external tooth surface conventional preparations, all accessible enamel margins usually are beveled, with the exception of the gingival margin.

Modified Class III Tooth Preparation:It is indicated for small and moderate lesions or faults and is designed to be as conservative as possible. The preparation design is dictated by the extent of the fault or defects and is prepared from a lingual approach when possible, with an appropriate size round bur or diamond instrument. Thus, the preparation design appears to be scooped or concave.

For a larger modified preparation, the preparation is start from the lingual approach by making an opening using a round carbide bur (No. , 1, or 2) or diamond instrument depending on the size of the lesion. At this initial preparation stage, an axial wall should be of limited depth, 0.2 mm internal of the DEJ. Final preparations steps for the modified tooth preparations are :

1. Extension of out line form to include the fault

2. Removal of infected dentin

3. Pulp protection

4. Bevel placement on accessible enamel margins and

5. Final procedure of cleaning and inspecting

Tooth preparation for class IV composite restorationThe class IV composite restoration has provided the profession with a conservative treatment to restore fractured, defective, or cariously involved anterior teeth when, previously, a porcelain crown may have been the treatment of choice.

Conventional Class IV Tooth Preparation:

Class IV restoration that extends onto the root requires a 90-degree cavosurface margin and possible groove retention form, regardless of whether either a beveled conventional or modified preparation design is used for the portion of the preparation in the crown of the tooth.

Beveled Conventional Class IV Tooth Preparations: indicated for restoring large proximal areas that also include the incisal surface of an anterior tooth. When there is a faulty or fractured class III restoration , which upon removal may need this type of preparation.

Using an appropriate size round carbide bur or diamond instrument, prepare the outline form to remove all weakened enamel and establish the initial axial wall depth at 0.5 mm into dentin.

Excavate any remaining infected dentin as the first step of final tooth preparation. If necessary, apply a calcium hydroxide liner.

Bevel the cavosurface of all accessible enamel margins of the preparation. The width the bevel should be 0.25 to 2 mm, depending on the amount of tooth structure missing and the retention perceived necessary.

In addition to the etched enamel margin, retention of the composite restorative material in beveled conventional Class IV tooth preparations may be obtained by groove or other shaped undercuts, dovetail extension, threaded pins, or a combination of these. Although pin retention is sometimes necessary, the use of pins in composite restorations is discouraged

Modified Class IV Tooth preparation: is indicated for small or moderate Class IV lesions or traumatic defects.

Usually no groove or cove retention form is indicated. Instead, the retention is obtained primarily from the bonding strength of the composite to the enamel and dentin.

Class IV fracture without caries involvement as such does not necessitate preparation of retention groove or other undercut. Preparation of chamfer approximately 0.3mm in depth, extending 2-3mm long around the margin followed by placing of long bevel with flame-shaped or long tapered diamond stone, along the cavosurface margin completed the tooth preparation.

Class V Tooth preparations:

Conventional Class V Tooth preparation: indicated for the portion of a carious lesion or defect entirely or partially on the facial or lingual root surface of a tooth.

Because many Class V carious lesions or defects will have some enamel at the incisal (occlusal) and possibly the mesial and/or distal margins, the conventional composite tooth preparation design is indicated only for the portion of the lesion or defect extending onto the root surfaceA tapered fissure carbide bur or similarly shaped diamond is used at high speed with air water spray. If access interproximally or gingivally is limited a No. 1 or No. 2 round bur or diamond may be used.

When a tapered fissure bur or diamond is used, make an entry at a 45 degree angle to the tooth surface by tilting the handpiece distally, however as a cutting progresses distally, maneuver the handpiece to thereafter maintain the burs long axis perpendicular to the external surface of the tooth during preparation of the outline form, which should result in 90-degree cavosurface margins.

At this initial tooth preparation stage, the extensions in every direction are to sound tooth structure, except the axial depth should only be 0.75mm.

Final tooth preparation consists of the following steps:

Removing remaining infected dentin or old restorative material (if indicted) on the axial wall

Applying a calcium hydroxide liner, only if necessary Sometimes preparing groove retention form

If retention grooves are necessary, they are prepared with a No. bur along the full length of the gingival axial and incsio-axial (occluso-axial) line angles.

Beveled conventional Class V Tooth preparation:

Indicated for:

The replacement of an existing defective Class V restoration that used a conventional preparation

For a large new carious lesion

Advantages

Increased retention due to the greater surface area of etched enamel afforded by the bevel

Decreased microleakage due to the enhanced bond between the composite and the tooth

Decreased need for groove retention form (and consequently less removal of tooth structure)

Modified Glass V Tooth Preparation:

Indicated for small and moderate Class V lesions or defects. The lesion or defect is scooped out, resulting in a preparation form that may have a divergent wall configuration and an axial surface that usually is not uniform in depth

Class V Tooth preparation for

Abrasion: in the form of notch, often V shaped is a loss or wearing away of tooth structure due to mechanical forces, such as strenuous tooth brushing with a hard bristle toothbrush or abrasive toothpaste.

Erosion : often a saucer shaped notch, occurs primarily as a result of chemical dissolution (e.g., sustained exposure to citric acid(juices or vomitus).

Idiopathic erosion or abfraction may occur as a result of flexure of the cervical area under heavy occlusal stress beginning with microfracture of the thin enamel tooth structure occlusal of the cementoenamel junction, which when combined with abrasive tooth brushing, could produce a notched defects. These notches are progressive, enlarging with time if the causative factor is not eliminated.

Tooth preparation for Aberrant Smooth surface Pit Fault:

Faults existing entirely in enamel are prepared with an appropriately sized round diamond instrument by merely eliminating the defect. Adequate retention is obtained by etching the enamel . When the defect includes carious dentin, the infected portion is removed also, leaving a flared enamel margin.

Pit and Fissure sealants, Preventive resin and conservative composite restorations, and Class VI composite restorations.

Long-term clinical studies indicate that pit and fissure sealants provide a safe and effective method of preventing carries. Sealants are most effective in children when they are applied to the pits and fissures of permanent posterior teeth immediately upon eruption of the clinical crowns.

Clinical studies also show that sealant can be applied even over small cavitated lesions, with no subsequent progression of caries

Conservative composite and preventive resin restorations: When restoring small pits and fissures on an unrestored tooth, an ultraconservative, modified preparation design is recommended. This design allows for restoration of the lesion or defect with minimal removal of tooth 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

Class VI Composite restoration:The typical Class VI tooth preparation should be as small in diameter and as shallow in depth as possible. Enter the faulty pit with a small, round bur (No. or No. ) or diamond oriented perpendicular to the surface and extend pulpally to eliminate the defect

Tooth preparations for Class I composite restoration: Conventional Class I Tooth Preparation: For the large Class I composite tooth preparation, enter the tooth in the distal pit area of the faulty occlusal surface, with an inverted cone diamond, positioned parallel to the long axis of the crown. Prepare the pulpal floor to an initial depth of 1.5 mm, as measured form the central groove. Once the central groove area is removed, the facial or lingual measurement of this depth will be greater usually about 1.75 mm, but this depends on the steepness of the cuspal inclines. Normally this initial depth is approximately 0.2 mm inside (internal to) the DEJ. The diamond is then moved medially to include other remaining faults, following the central groove, as well as any fall and rise of the DEJ. Facial and lingual extension and width are dictated by the caries, old restorative material, or fault. After extending outline form to sound tooth structure, if any caries or old restorative material remains on the pulpal floor, it should be removed with the diamond or a round carbide bur

No attempt is made to place additional beveling on the occlusal margin because it may result in thin composite in areas of heavy occlusal contract.

Also, the inverted cone diamond result in occlusal walls that converge occlusally, thereby enhancing retention form.

Because of the occlusal surface enamel rod direction, the ends of the enamel rods are already exposed by the preparation which further reduces the need for occlusal bevels.

The marginal form of a groove extension on the facial or lingual surface may be beveled with the diamond, resulting in a 0.25 to 0.5 mm width bevel at a 45-degree angel to the prepared wall.

Modified class I tooth preparation: Minimally involved Class I lesions or faults may be restored with preparations are less specific in form, having a scooped out appearance. Typically, they are prepared with a small round or inverted cone diamond. The initial pulpal depth is still 1.5mm or approximately 0.2 mm inside the DEJ, but may not be uniform (i.e, the pulpal floor is not necessarily flat throughout its length.)

Tooth preparation for class II composite restoration

Conventional Class II tooth preparationOcclusal Step: The occlusal portion of the Class II preparation is prepared similarly as described for the Class I preparation. Initial occlusal extension toward and involved proximal surface should go through the marginal ridge area at initial pulpal floor depth, exposing the DEJ. The DEJ serves as a guide for preparing the proximal box portion of the preparation

Use No. 330 or No. 245 shaped diamond enter the pit opposite the faulty proximal surface, the diamond is positioned parallel with the long axis of the tooth crown. If only one proximal surface is being restored, the opposite marginal ridge dentinal support should be maintained. This may require using the proximal side of the diamond to include the faulty pit near the marginal ridge of the unaffected proximal surface, especially in smaller teeth the entire central groove area may not need to be included, and only the faulty areas are prepared.

Every effort should be made to keep the faciolingual width of the preparation as narrow as possible. The initial depth is maintained during the mesiodistal movement but follows the rise and fall or the underlying DEJ. If caries is still present in enamel on the pulpal floor at the initial depth of 1.5 mm, then the pulpal floor is extended 0.2 mm inside the DEJ, if caries remains in the dentin, it is removed as part of final tooth preparation.

Proximal box: Typically caries develops on a proximal surface immediately gingival to the proximal contact. The extent of the carious lesion or amount of old restorative material are two factors that dictate the facio- lingual and gingival extension of the proximal box of the preparation. If all of the fault can be removed without extending the proximal preparation beyond the contact, the restoration of the proximal contract with the composite ( a major difficulty) will be simplified.

Once the diamond is extended through the marginal ridge, be careful not to cut the adjacent tooth, the proximal ditch cut is initiated that will be 0.2 mm inside the DEJ. The diamond is then extended facio- lingually and gingivally to include all of the fault caries or old material. The Facio-lingual cutting motion follows the DEJ and therefore is usually in a slightly convex arch outward.

During this entire cutting, the diamond is held parallel to the long axis of the tooth crown. The gingival floor is prepared flat with an approximately 90- degree cavosurface margin. Gingival extension should be as minimal as possible trying to maintain an enamel margin. The axial wall should be 0.2 mm inside (internal to the DEJ and have a slight outward convexity.

If the preparation extends onto the root surface, more attention must be focused on keeping the area isolated during the bonding technique, but no difference in tooth preparation are required. The preparation portion on the root should have

A 90 degree cavosurface margin

An axial depth of approximately 0.75 to 1 mm

Usually no secondary retention features are incorporated.

The only remaining final tooth preparation procedure that may be necessary is additional excavation of infected dentin on either the pulpal floor or axial wall. A round bur or appropriate spoon excavator is used to remove any remaining infected dentin.

Thus, the conventional Class II composite tooth preparation is similar to that for amalgam, except no secondary retention featuresconservative preparation design may be used. A small round or inverted cone diamond may be used for this preparation to scoop out the carious or faulty material. This scooped appearance occurs on both the occlusal and proximal portions. The pulpal and axial depths are dictated only by the extent of the lesion, but may require the use of another diamond with straight side to prepare walls that are 90 degrees or greater.

Facial or lingual slot preparation: a lesion is detected on the proximal surface but the operator believes that access to the lesion can be obtained form either a facial or lingual direction, rather than through the marginal ridge in a gingival direction. Usually a small round diamond is oriented at the correct occluso-gingival position and the entry is made with the diamond as close to the adjacent tooth as possible, thus preserving as much of the facial or lingual surface as possible.

The preparation is extended occlusally, facially and gingivally enough to remove the lesion. The axial depth is 0.2 mm inside the DEJ. The occlusal, facial, and gingival cavosurface margins are 90 degrees or greater. This preparation is similar to a Class III preparation for an anterior tooth.

VENEERSA veneer is a layer of tooth colored material that is applied to a tooth to resort localized or generalized defects and intrinsic discolorations.

Veneer can be of tow types:

Partial veneers

Full veneers.

Partial veneers are indicated for the restoration of localized defects or areas of intrinsic discoloration.

Full veneers are indicated for the restoration of generalized defects or areas of intrinsic staining involving the majority of the facial surface of the tooth. However, several important factors, including patient age, occlusion, tissue health position and alignment of the teeth, and oral hygiene, must be evaluated before pursuing full veneers as a treatment option.

Indirect veneers require two appointments but typically offer the advantages over directly placed full veneers.

Tooth preparations for veneers

Some controversy exists regarding the extent of tooth preparation that is necessary and the amount of coverage for veneers. Intra-enamel preparation (or the roughening of the surface in undercontoured areas) before placing a veneer is strongly recommended for the following reasons:

To provide space for opaque, bonding, or veneering materials for maximal esthetics without over contouring

To remove the outer, fluoride rich layer of enamel that may be more resistant to acid etching.

To create rough surface for improved bonding

To establish a definite finish line

Establishing an intra-enamel preparation with a definite finish line is of particular importance when placing indirectly fabricated veneers. Accurate positioning and seating of and indirectly made veneer are significantly enhanced if an intra-enamel preparation is present

Another controversy involves the location of the gingival margin of the veneer. Should it terminate short of the free gingival crest at the level of the gingival crest or apical of the gingival crest. The answer depends on the individual situation.

If the defect or discoloration does not extend subgingivally, then the margin of the veneer should not extend subgingivally.

The only logical reason for extending the margin subgingivally is, if the area is carious or defective warranting restoration, or if it involves significantly dark discoloration that presents a difficult esthetic problem. Clinicians should remember that no restorative material is as good as normal tooth structure, and the gingival tissue is never as healthy when it is in contact with an artificial material.

Two basic preparation design exist for full veneers:

A window preparation and

An incisal, lapping preparation.

A window preparation is recommended for most direct and indirect composite veneers. This intraenamel preparation design preserves the functional lingual and incisal surfaces of an maxillary anterior teeth, protecting the veneers from significant occlusal stress. This design is particularly useful in preparing maxillary canines in a patient with canine-guided lateral guidance. By using a window preparation, the functional ;surfaces are better preserved in enamel.

An incisal lapping preparation is indicated when the tooth being veneered needs lengthening or when an incisal defect warrants restoration.

Additionally, the incisal lapping design is frequently used with porcelain veneers, because it not only facilitates accurate seating of the veneer upon cementation, but it also allows for improved esthetics along the incisal edge.

The preparation and restoration of a tooth with a veneer should be carried out in a manner that will provide optimal function, esthetics, retention, physiologic contours, and longevity. All of these objectives should be accomplished without compromising the strength of the remaining tooth structure.

Darkly stained teeth, especially those discolored by tetracycline, are much more difficult to veneer with full veneers than teeth with generalized defects, but normal coloration. The difficulty is further compounded when the cervical areas are badly discolored.

Discolored mandibular anterior teeth are rarely indicated for veneers, because the facioincisal portions are thin and usually subject o biting forces and attrition. Therefore veneering lower teeth is discouraged if the teeth are in normal occlusal contact, because it is exceedingly difficult to achieve adequate reduction of the enamel to totally compensate for the thickness of the veneering material. Fortunately, in most cases the lower lip hides these teeth, and esthetics is not as much of a problem.

Direct veneer techniques

Direct partial veneersSmall localized intrinsic discolorations or defects that are surrounded by healthy enamel are ideally treated with direct partial veneers. The outline form is dictated solely by the extent of the defect and should include all discolored areas. The clinician should use a coarse, elliptical or round diamond instrument with air water coolant to prepare the tooth to a depth of about 0.5 tp 0.75 mm

Direct full veneersThe window preparations is typically made to a depth roughly equivalent to half the thickness of the facial enamel, ranging form approximately 0.5 to 0.75 mm midfaically and tapering down to a depth of about 0.2 to 0.5 mm along the gingival margin, depending on the thickness of enamel. A heavy chamfer at the level of the gingival crest provides a definite preparation margin for subsequent finishing procedures. The margins are not extended subgingivally because these areas are not defective.

The preparations for a direct veneer normally is terminated just facial to the proximal contact, except in the area of the diastema. To correct the diastema, the preparations are extended from the facial onto the mesial surfaces terminating at the mesiolingual line anglesIndirect processed composite veneers also are indicated for placement in patients who exhibit significant wear of their anterior teeth caused by occlusal stress. Because of their somewhat lower cost.

SELECTION AND PLACEMENT OF MATRIX SYSTEM AND GINGIVAL WEDGEA matrix device that may be applied to a prepared toot , fits around part or all of the tooth to be restored and functions primarily to confine the restorative material on the axial surfaces.

Objectives of matrix placement Provide proper contact and contour

Confine the restorative material

Reduce the amount if excess material

Requirements to be effective it should be be easy to easy to apply and remove

extend below the gingival margin

extend above the marginal ridge height

resist deformation during material insertion

The matrix band may need to be altered to have appropriate contour for a desired shape of a restoration. It is held in place by the gingival wedges, and in some instances by a matrix retainer. Regardless of the use of the matrix retainer, the gingival wedges are placed in to the gingival embrasure and are positioned between the two adjacent teeth, below the prepared gingival margin, and exterior to the matrix material.

The wedges function to:

separate the teeth to compensate for the thickness of the matrix material, as it relates to establishing a proximal contact

hold the matrix in place

Prevent or reduce any excess restorative material at the gingival margin.

Selection of Matrices: numerous matrix systems are available in the market , such as-

1. Polyester matrix (transparent matrices)-mainly used for class III and class IV restoration

2. .Metal matrices-

Metal tofflemire matrx- currently ultra thin ().001inch) universal metal matrix systems are available which can be used for class II composite restoration , retained by tofflemire retainer, Eg- HO Bands, Young Dental Company, Earth City, Missouri.Self adjustable circumferential metal matrix-

Eg- Auto- matrix system, Dentsply/Caulk, Milford, DE USA

Dead soft metal matrix, Dent Mat Corporation , Santa Maria California

3M Matrix system (3M- ESPE)

Most of the matrix system have clamps to stabilize the matrix in position and improve their adaptation to the buccal and lingual walls of the prepared tooth . However, they can be supported by modeling compound .

Wedges:

Several types of wedges are also available in assorted sizes

A triangular-shaped (plastic) wedge is indicated for preparation with margin that are deep in the gingival sulcus.

An end of a round wooden tooth pick approximately 3/8inch (9mm) long usually is an excellent wedge.

Placement of matrix band matrix placement preceding etching, and bonding procedure , provide best isolation for maximum enamel and dentin adhesion. This sequence is especially beneficial in tooth prepared with deeply extended gingival margin. This also allow to assess of any enamel fracture (upon insertion of the proximal wedges) before bonding to that area

ETCHING AND BONDING PROCEDURE

The acid etch technique requires that a very exacting sequence be followed if optimal results are to be obtained. The etchants are available both in liquid and gel form, most in concentration of 32% to 37% phosphoric acid.

The gel form is preferred due to its thixotropic property which helps in application of the etchant to the preparation wall including bevel and margin The etchant gel can be placed carefully with brush or endodontic paper points held in cotton pliers, but usually a syringe applicator is used to inject a gel etchant directly on to the prepared tooth structure .

The etched surfaces must not be contaminated by oral fluids; Such contamination adversely affects the etch and requires repeating the etching procedure. For preparation involving the proximal area, a polyester matrix strip is placed between teeth before the acid is applied to prevent inadvertently etching the adjacent tooth.

Regardless of the form of the enchant, the acid is gently applied to the appropriate surfaces to be bonded ,keeping the excess to a maximum of 0.5 mm past the anticipated extent of the restoration .The etching time of 15 seconds for both dentin and enamel is considered sufficient .For the preparations limited with in the enamel require 30 second of etching time.

The enchant area is rinsed for 5 to 15 seconds, starting on the adjacent tooth to prevent possible splashing of acid rich water on to the patient, operator ,or assistant .

The area should be dried with clean ,dry air from the air-water syringe if only enamel has been etched .If both enamel and dentin has been etched, then the area must be left slightly moistened (should not be dried more than 5 seconds). This allows the primer and adhesive materials to more effectively penetrate the collagen fibril to form a hybrid layer

Etch is the basis for micro mechanical bond to dentin .Over drying etched dentin surfaces compromises dentin bonding as a result of the collapse of the collagen network in the etched dentin layer . This collapse prevents optimal primer and adhesive penetration and compromises hybrid layer formations .If dentin wall have been dried ,they should be rewetted with a water saturated applicator tip ( or Gluma Desensitizer)

SELECTION OF COMPSITE RESIN

In selecting a composite resin one must consider strength, polymerization shrinkage, finishing and polishing ability.

Hybrid composites:The compressive and wear resistant exhibited by hybrid composites make them suitable for application on posterior teeth. Such characteristics are result of high filler percentage (above 60 % in volume) of the composites. The hybrid composites are nothing but mixtures of various sized filler particle (0.04-3 m) with a minimum of 7 to 15 % micro fill particles.

Microhybrid or minifilled hybrid compositesReferred to composites with a filler load percentage similar to that of hybrid composites. Microhybrid have a smaller average particle size (0.8 to 1.0 m), they have a more uniform filler load distribution, which makes them easier to light cure9. As a result, microhybrid composites have a grater polishing capacity then do hybrids and exhibit excellent mechanical properties. Their acceptance resulted in the development of minifield hybrid composite with and even smaller average particle size (0.4 to 0.6 m). The minifilled composites exhibit excellent polishing capacity.

Pack- able composite:is preferred by that restorative dentist who is used in doing amalgam restoration; because it can be packed or condensed like silver or amalgam alloy. The packable characteristic is due to the incorporation of spiral structure of filler particles that reinforces the resin matrix.

.

Flowable CompositeThe flowable composite exhibits low modulus of elasticity due to its lower filler contents and shows lower wear resistance and strength.

More appropriate for small class-I restoration, as pit and fissure sealant, as a liner in deep cavity under hybrid or micro-hybrid or packable composite.

Due to its wettability and injecting capacities it is chosen as the 1st layer in the preparations where the margins are gingivally extended.

Due to its lower modulus of elasticity, it is the material of choice for class-V restoration.

For anterior restorations, the material selected should exhibit excellent polishability, so; microfilled and/or minifilled composites can be selected for such restorations

INSERTION AND CURING OF COMPOSITE RESIN

The composite restoration is usually placed in two stages:

First, bonding receipt is applied.

Second, the composite restorative material is inserted.

Either a hand instrument or a syringe can be used for inserting self-cure or light cure composite .The use of hand instrument is popular; because, it is easy and fast. In addition, a smaller amount of composite material is required compared to the amount needed for the syringe method

Disadvantage of hand instrument insertion is that air can be trapped in the tooth preparation or incorporated into the material during the insertion procedures.

The syringe technique is popular because it provides a convenient means for transporting the composites to the preparation and reduces the possibility of trapping air. Many manufactures provide preloaded syringe compules with a light cure composite .The tip of the light cure have covers that should be replaced when not using the material to keep from being polymerized in adherently by ambient light.

Insertion TechniqueGenerally two insertion techniques are followed:

1) Bulk insertion technique a single application of composite and subsequent polymerization. This technique is generally used to restore small modified preparations (class- III, class- I, class II box and slots preparations) and for preventive restorations.2) Incremental or layering technique composite resin is inserted in two or more layers to restore the preparations. Large conventional and preparations, mainly class-I, class-II, and class-IV preparations are restored using this insertion technique.

The main short coming of direct composite is that the placement technique has to compensate for the unavoidable polymerization shrinkage, especially in class-II and larger class-I preparations. To that effect numerous procedures have been proposed:

Segmentation of the polymerization by multilayer techniques (Lutz and Kull, 1980; Tjan et al,1992

Use of condensation and polymerization tips ( Erikcson and Derand, 1991; Jorgensen and Hisamitu,1984).

CONFIGURATION FACTOR (C-FACTOR):Ratio of bounded surface to unbounded surface

So, C-factors for different types of composite restoration can be equated as follows:

The higher the C- factor, the greater is the potential for bond disruption from polymerization effects

Due to polymerization shrinkage internal stresses are generated at the interface of composite resin and prepared tooth surfaces. This stresses are released through the open or unbounded tooth surfaces that causes bond disruption and gap formation. This is more obvious in Class-I restoration with the C-factor particularly along the papal floor which may causes pain on chewing.

To reduce these internal stresses, the following steps can be considered:

1) Incremental insertion technique

2) Soft- start polymerization instead of high intensity light curing

3) Stress breaking liner, such as compomers, flowable composite or RMGI

LIGHT- CURING

Today, the restorative dentists have the choices of the light sources between halogen, plasma-arc, and LED lamps with energy level that ranges from 350 to far above 1000 mW/cm2

According to the ISO specification of polymerization, light source, energy output must be measured only for the spectral region of 460 to500nm

The light curing time depend on the structure and composition of the material used, site, size and depth of the restoration, and also to the energy level of the light source used for curing the restoration

When conventional halogen light source with standard energy level is used for curing the resin composites containing the camphoroquinone as initiator, generally the following time regimens for each increment can be followed:

Opaque layer-40 sec., body and enamel -20 sec. each layer, Flowable composite -40 sec., Packable composite-40 sec.

Practitioner always desire a short irradiation time combined with high, uniform conversion and low polymerization shrinkage stress. Swift conversion is proportionally accompanied by rapid hardening, which can negatively affect the marginal integrity of the adhesive restoration. Prolonged irradiation time is more effective for proper conversion than increased energy. The uses of extremely short high energy irradiation might have disadvantages regarding the quality of the overall conversion, could still lead to better restorations where isolation control is critical

CONTOURING THE COMPOSITE

Contouring can be initiated immediately after a light cure material has been polymerized or 3 minutes after the initial hardening of a self cure material.

Usually a slight amount of material is present to remove to provide the final contour and smooth finish if insertion of the composite done following adequate technique.

Coarse diamond instrument can be used for removing gross excess but are not generally recommended for finishing the restoration because of the high of inadvertently damaging the adjacent tooth structure. They also leave a rough surface on the restoration and tooth compared to finishing bur and disc.

For final contouring or finishing diamond or carbide bur is recommended.

During contouring the restoration special attention should be given to copy the surface anatomy of the adjacent and/or contra lateral tooth. Proper surface texture of the composite restoration is relatively difficult to achieve, demanding intensive training, meticulous attention and very close observation of the surrounding natural tooth. Attention must be given to establish proper occlusal contact and anterior guidance

FINISHING AND POLISHING PROCEDURESThe finishing and polishing procedures have always been indicated to give composite restoration an extended life offered by greater surface smoothness, enhanced esthetic characteristics, reduced amount of plaque less surface discolorations, comfort in the adjustment of the occlusion, correction of anatomy, and removal of marginal excesses (flashes).

To start with 12/30 bladed carbide finishing burs under high speed without water spray. A few examples are Esthetic Trimming TM (ET) set by Brasseler, or finishing burs nos. E0510L, E0512, E0516, E0534 by Dentsply maillefer.

Enhance TM composite finishing and polishing kit by Dentsply is one of the best finishing kits especially for posterior composites

Sof Lex TM contouring and polishing discs by 3M is another fine system for composite finishing.

If Sof Lex TM is used, finishing should be started with coarse, medium, fine and superfine grades. The advantage of using Enhance TM is that only one grit is needed to make the surface smooth.

For final enamel like polish, Prisma Gloss TM (aluminous oxide) is a very good polishing paste when used with rubber cup or synthetic foam polishing cup supplied with the enhance TM kit (Dentsply).

Composite should never be overheated while polishing. Abrasives should be used with slow speed and light pressure.

Well-polished composite lasts longer because it attracts less plaque and stains and is more wear resistant.

The polished composite restoration can be coated with a surface sealant or bonding agent which are then cured .This step can fill the micro cracks that may be result from finishing and polishing procedure and also the microporisities on the restoration as well as unrestored tooth surfaces. This post polishing step of application of surface sealants or bonding agents are capable of reducing wear rates upto 50% when compared to non sealed restoration. It is imperative to seal the restorative margin and surfaces every 12 months, to maintain wear protections.

GUIDELINES (TO REDUCE POSTOPERATIVE SENSITIVITY AND PULPAL DAMAGE)To start with a clean uncontaminated enamel and dentin surface.

If isolation is difficult, for example in 2nd molars, enamel should be etched but not the dentine. Etching of dentin will open up the dentinal tubules and subsequently not be able to seal them with dentin adhesives, it would be a more than 15 secs good invitation for bacterial to reach the pulp. Dentin should not be etched for.

.

If remaining dentin thickness is less than 1 mm. from the pulp, it is advisable not to etch the dentin and to use a self-etching primer like Prime and Bond N.T. TM on the dentin and cover with a thin layer of a flowable compomer ( Dyract Flow TM, Dentsply). Next, the remaining enamel should be etched, washed and covered the entire preparation with Prime and Bond N.T. TM followed by the restorative material. This step is particularly effective in getting a good seal, preventing voids and for fluoride release

After washing the etchant, over drying (desiccate) the dentin with the air syringe should be avoided. For drying cotton pellet or suction or air syringe for 1 sec. can be used.

Preferably filled adhesives e.g. Prime and Bond N.T. TM (Dentsply), Optibond Solo plus TM (Kerr) should be used. Less sensitivity has been reported with filled adhesives. Fillers reinforce the hybrid layer and reduce micro leakage even under stress of polymerization shrinkage and occlusal loading. The dentin adhesive should be applied gently adhesive for 20 secs.with the applicator tip taking care to keep the dentin wet with the

Air syringe for 5 seconds should be use to evaporate the solvent and then to be light cure for 10 seconds before placing restorative material.

In deep cavities and on gingival steps of class II restoration a flowable compomer like Dyract Flow TM is placed as first increment to prevent voids. The next increment used should be of a good creamy hybrid like TPC Spectrum Tm or a packable composite like Sure Fill TM or a compomer like Dyract TM

Each increment of composite should be cured adequately with a good power light. The light should have radiometer, which advises when it is time to change the bulb or filter. Uncured resin at the base of the cavity can be an important cause of postoperative sensitivity.

REVIEW OF LITERATURE

N.Barghi et al (1991)17 - evaluated and compared the bond strength of composite resin to acid etched enamel with and without the use of a rubber dam. Cylindrical-shaped composite resin rods were bonded to teeth treatment planned for extraction. Methods utilized for controlling moisture were: a) placement of a rubber dam and b) the use of cotton roll isolation.

Following extractions bonded resins were subjected to shear bond strength testing. The following conclusions were made.1. Overall, utilization of the rubber dam for moisture control and isolation resulted in significantly higher shear bond strength of composite resin to enamel. Results were consistent between the tested patient, teeth of each patient and between the tested teeth of all 2. The mode of fracture between enamel and composite resin may differ between in vitro and in vivo conditions. Additional studies are needed to further clarify this difference

Tjan AHet al (1992)23 - compared the effects of various placement techniques on the formation of micro-gaps at the gingival margins of class II composite resin restorations. Three incremental techniques (occlusogingival layering, oblique layering, and faciolingual layering) and two one-bulk techniques of placing composite resin were studied. In the first one-bulk placement technique the composite resin was photocured occlusally; in the second one-bulk technique the composite resin was irradiated from three directions; facial, lingual, and occlusal. None of the incremental placement techniques improved the adaptation at the gingival margin compared with a one-bulk technique irradiated occlusally. However, the one-bulk placement technique that was irradiated from three directions created a substantial marginal discrepancy.

John R. Condon et al (2000)11 measured the magnitude of the polymerization stress of a variety of dental composite materials and explored the effect of a novel monomer, methacrylated derivative of styrenene-allyl alcohol, or MSAA, in reducing polymerization stress. They concluded that composites that contain lower level of filler particles are less likely to produce high level pf polymerization stress during placement. Modification to traditional composite chemistry can result in materials that can produce lower polymerization stress levels. The clinical implication drawn from their study is that the polymerization stress produced by dental composite materials during light curing is a leading reason for bond failure in adhesive restorations, resulting in post operative sensitivity, marginal staining and recurrent caries.

Cobb DS et al (2000)5- compared the physical properties of three packable hybrid resin-based composites with those of a conventional hybrid and a microfill composite material advocated for use as posterior restorative materials. They concluded, the packable composites tested in this study had physical properties superior to those of the microfill composite, they were no better suited for use as a posterior restorative material than was the conventional hybrid resin-based composite. CLINICAL IMPLICATIONS: Packable composites may be easier for clinicians to handle than conventional resin-based composites; however, their physical properties were not superior to those of the conventional small-particle hybrid resin-based composite. In addition, these materials may have the clinical drawback of increased wear and surface roughness that was seen with early, large-particle composite restorative materials

Chen HY et al (2001)4 - Determined the polymerization contraction stress of packable composites (ALERT, Surefil, Solitaire, Solitaire 2) and a packable ORMOCER material (Definite) in comparison with a conventional hybrid composite (Tetric Ceram) High contraction stress and rapid contraction force development can lead to failure of bond to tooth structure. This study suggested that, packable composite resins are less capable of reducing the contraction stress during the early setting stage, thus not superior in maintaining the bond with cavity walls compared to conventional hybrid composite (Tetric Ceram.)

Idriss, C. Habib et al (2003)10 compared marginal gap formation in class II resin composite restorations. Forty caries-free extracted molars were prepared in a standardized manner for class II restoration by one of four methods: bulk- or incrementally-placed light-activated resin composite (Amelogen), and bulk- or incrementally-placed chemically activated composite (Rapidfill). although method of placement of a given material had no significant effect on the quality of marginal adaptation, both of the chemically activated resin composite restorations produced significantly smaller marginal gaps than both the bulk- and incrementally-placed light-activated composites

Guilherme Carpena (2004)9 reviewed some concepts about the adhesive restorative procedure and presented two case reports illustrating the step by step procedure for direct posterior composite restorations. They highlighted few critical points to receive careful attention: correct field isolation, adhesive application, insertion and polymerization of composites, selection and insertion of the matrix system, and proper adjustment and finishing of the restoration. Taking all the care, a properly inserted and controlled resin restoration on posterior teeth can often function for 10 years or more.N. Attar et al (2004)16- investigated the effect of flowable resin material on gingival micro leakage of microhybrid and packable resin restorations. The result obtained in this study indicates that the use of flowable resin materials as a gingival increment of class-II restorations with packable and micro-hybrid composites decreased the micro-leakage. .

CONCLUSIONThe use of composite restoration is increasing because of the benefit accrued from adhesive bonding to tooth structure, esthetic qualities, and almost universal clinical usage. When done properly, a composite restoration can provide excellent service for many years. However, composite restorations are more difficult and technique sensitive to operator ability than amalgam restorations. To effect the bond that provides the benefit, the operative site must be free from contamination. Meticulous care should be taken while performing the every step of the restorative procedure. Hence to get the strong bond of the composite with the tooth structures and clinically and functionally durable restoration.

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7. Didier Dietschi, Roberto Spreafico-Adhesive Metal-Free Restorations, Current Concepts for the Esthetic Treatment of Posterior Teeth, Quintessence Publishing Co,Inc;1998 8. Fusayama T. : Total etct technique and cavity isolation, J. Esthet. Et. 1992,4:150-599. Guilherme Carpena Lopes, Luis Clovis Cardoso Vieira, Elito Araujo- Direct composite restorations: A review of some clinical procedures to achieve predictable result in posterior teeth., J Esthet Restor Dent 16:19-32, 200410. Idriss*, C. Habib*, T. Abduljabbar & R. Omar- Marginal adaptation of class II resin composite restorations using incremental and bulk placement techniques: an ESEM study , Journal of Oral Rehabilitation Volume 30Issue 10Page 1000 - October 2003doi:10.1046/j.1365-2842.2003.01082.x

11. John R. Condon, B.S.; Jack L. Ferranace- assessing the effect of composite formulation on polymerization stress, JADA,Vol.131:497-503,April2000.

12. Leevailoj C, Cochran MA, Matis BA, Moore BK, Platt JAMicroleakage of posterior packable resin composites with and without flowable liners. Oper Dent. 2001 May-Jun;26(3):302-7

13. Mair LH:Ten years clinical assessment of three posterior resin composites and two amalgams, Quintessence Int 29:483-490, 1998

14. Manhart J, Chen HY, Hickel R. -The suitability of packable resin-based composites for posterior restorations. J Am Dent Assoc. 2001 May;132(5):639-45.

15. Mertz-Fairhurst EJ et al: Caristatic and ultraconservative sealed ewstorations: six year results, Quintessence Int 23(12):827-838, 1992.

16. N. Attar, M.D.Turgut, H C Gungor The effect of flowable resin composites as gingival increments on the micro leakage of posterior resin composites.Oper. Dent., 2004, 29-2,162-67.

17. N.Barghi,G T Knight, T G Berry-Comparing two methods of Moisture control in bonding to enamel: A clinical study, Oper Dent.1991;16:130-35.

18. Quellet D. - Considerations and techniques for multiple bulk-fill direct posterior composites. Compend Contin Educ Dent. 1995 Dec;16(12):1212, 1214-6, passim; quiz 1226

19. Raskin A, Setcos JC, Vreven J: influence of isolation method on the 10 years clinical behavior of posterior resin composite, Clin Oral Investig 25:148-152, 2000.Rei naldo de Souza Ferreira, Guilherme Carpena Lopes, Luiz Narciso Baratieri- Direct posterior resin composite restorations: consideration on finishing and polishing, Clinical procedures, Quintessence Int 2004;35:359-66.

20. Smales R.J. - Rubber dam usage related to restoration quality and survival Br. Dent. J. 1993, 174:330-33

21. Sturdevants Art and Science of Operative Dentistry 4th ed-2001, Mosby St. Louis,

22. Swift EJ Jr: thr effect of sealants on dental carie : a review, JADA 116:700-704, may 1998

23. Tjan AH, Bergh BH, Lidner C. - Effect of various incremental techniques on the marginal adaptation of class II composite resin restorations.J. Prosthet Dent. 1992 Jan; 67(1):62-6.

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