The Composite Inlay is an excellent procedure which can be incorporated into clinical practice pretty fast and with remarkable ease if all the principles of composite restorations are understood and followed. Dr. Mona Kakar brings to you a very detailed step by step presentation of this procedure.

THE COMPOSITE INLAY

The Composite Inlay is a procedure which allows the clinician to restore badly damaged teeth efficiently and aesthetically by utilising the properties of modern day composite materials to its fullest extent. The beauty of this procedure is that it does not require very expensive equipment and armamentarium. It should be noted that it is a skilfull procedure and the end results are in absolute correspondence with the skill with which the dentist can recreate the tooth structure with composites.

PHASE ONE - TOOTH PREPARATION

Step One - Remove all caries with round burs of appropriate sizes.

Step Two - All cavity walls to be made flaring occlusally (approximately 6 to 10 degrees). Do not panic if a small area is flared more then the recommended amount. It will only facilitate the placement of the restoration and bonding will take care of retention of the inlay.

Step Three - Needless loss of tooth structure to eliminate gross undercut areas is to be avoided. Directly placed composite or light cured glass ionomer restorative can eliminate the undercut areas and create a conducive cavity form. Cavity form and depth is dictated primarily by the extent of carious involvement and/or the presence of previous restorations. Do not level the floor of the preparation. Leave any undulations that may have been created due to carious removal. The only thing to ensure is that no undercuts are left in and that a minimum of 1.5 mm depth is available for restoration.

Step Four - All line angles and point angles should be rounded so that there is no stress concentration in any area.

Step Five - The minimum depth of the preparation from the occlusal surface must be 1.5 mm at any given point. This must be attended to particularly in the region of the occlusal surface grooves since the thinnest section of the inlay fabrication will be in this region. If necessary, a small round bur can be used to create a dip or indentation in the preparation, corresponding to the pit and fissure areas of the occlusal surface.

Step Six - The external cavosurface margins of the preparation should have a sharp, well defined butt joint. Alternately, a grooved bevel (a hollow-ground chamfer), may be prepared with a round bur to help in the merging of the inlay with the surrounding natural tooth structure.

Step Seven - Do not connect two individual preparations on a single tooth if there is a minimum of 1 mm thickness of good tooth structure in between. Two individual inlays can be fabricated for the two sites.

Step Eight - In the case of proximal wall involvement, again keep all line and point angles rounded. Eliminate any undercut present along the proximal box walls by placement of composite or light cured GI.

Step Nine - DO NOT leave any liner or base cements or any old restoration segments in the preparation. The latest generation bonding agents do not warrant the use of any insulation agents.

PHASE TWO - IMPRESSION MAKING AND INLAY FABRICATION

Step One - If your preparation extends to anywhere near the gingival margins, the use of a retraction cord prior to impression making certainly makes the inlay fabrication much easier since the preparation margins will be well differentiated. A tip: whatever retraction cord you use, soak it in Astringednet, a hemostatic solution marketed by Ultradent. According to me, it is the best hemostatic in the world.

Step Two - Removed the retraction cord just prior to making the impression. Wet the cord and remove gently to avoid triggering any hemorrhage. The impressions (both arches), may be made with the impression material of your choice: an irreversible hydrocolloid, an elastomer or an addition silicone. Either way, make sure that the impression material flows properly into the deep areas of the preparation. A hint for hydrocolloid users: Take some material on the finger or in a disposable syringe and force material into the base of the preparation before placing the impression tray with the bulk of the material in the mouth.

Step Three - Match the shade. The dentin shade should be matched with any exposed dentin available. If the dentin has amalgam tattoos or other stains, the cervical area of the buccal surface would be a better bet. Make a note if there are base stains - you will have to use opaque composite as the base layer to mask those stains. The enamel shade should be matched with the occlusal surface of the tooth. Make a note of any surface stains on the adjacent teeth so that they can be duplicated in the restoration.

Step Four - Temporize. Any non-eugenol cement can be used as a temporary cover for the prepared tooth. Make sure that the margins are sealed well. Alternately, a provisional acrylic inlay can be fabricated and fit into the prepared tooth with a non-eugenol cement.

Step Five - Pour the model in die stone. Mount and section the die for fabrication of the inlay. Preferably use a quick setting stone if you are to fabricate the inlay yourself. Paint a separating medium on the die as well as on all the adjacent teeth. Gently air dry. The layer of separating medium must be even all over.

Step Six - Place the appropriate shade of hybrid composite resin in increments of 2 mm at a time into the preparation and light cure each increment as if you were building a direct restoration. Proximal contour (in case of proximal involvement), contact, occlusal anatomy and staining should be developed. Utilize the opposing arch model to check occlusion. Make sure that it too has separating medium on it so as not to have composite adhering to, and dragging with it.

Step Seven - Heat treat the inlay in a curing oven. The temperature achieved by these commercially available ovens is in the range of 100 to 120 degrees Celcius. The inlay is to be tempered for 10 to 15 minutes. It may be tempered while in place on the die or preferably after removal from the die. To facilitate removal and handling of an occlusal inlay, a wooden tooth pick can be attached to the occlusal surface with a small blob of composite and cured. An inlay involving a proximal surface can eaily be slid out of the die with occlusally directed pressure on the proximal surface.

Step Eight - Trim the excess material (fins, etc.), replace the inlay on the die and complete the finishing. Use the opposing arch model again to check occlusion. Any surface characterization that may have been eliminated during trimming, may be re-done at this stage.

Step Nine - Cleanse the final restoration in an ultrasonic cleanser.

PHASE THREE - TRIAL AND PLACEMENT OF THE RESTORATION

Step One - Remove the provisional restoration from the tooth, making sure that no portion of it is left adhering to the walls of the prepared tooth.

Step Two - Place the inlay into the prepared tooth. DO NOT force the inlay into the tooth. If the inlay does not seat completely into the tooth, it is probably due to an inadvertently overlooked undercut area in the preparation. You will receive a hint to this effect while removing the inlay from the die itself - it will probably have to be chipped or broken to remove the inlay. In such a scenario, use a contact detecting spray on the undersurface of the inlay to determine the interfering section and reduce that section. The inlay will then glide smoothly into place. Do not worry about the space created between the tooth and inlay due to the reduction - the luting agent (which itself is composite based), will occupy that space.

Step Three - Once the inlay is seated completely, check for marginal integrity, proximal contact and colour. The colour should match to within half a shade of the surrounding structure and teeth. Mild colour modifications can be acheived with incorporation of tints into the luting agent. If the proximal contact is open, composite material will have to be added to the appropriate area on the proximal surface. This is done after roughening the area on the inlay with a diamond bur or microabrading, then etching with phosphoric acid (37%) for 30 seconds, washing and drying and then applying a bonding resin and curing it for 20 seconds. Apply the composite and taper its edges so as to merge with the remainder of the proximal surface. Light cure the composite and check the seating and contact again. If satsifactory, polish the inlay, specifically the proximal surface which is difficult to access after seating. CAREFUL, do not reduce the marginal areas of the inlay lest they become deficient!!

Step Four - DO NOT check for occlusal harmony at the try-in stage. Remember: by itself, the composite inlay is a brittle entity, much like a thick sheet of glass and is likely to shatter if a sudden force is applied to it. It is only when the inlay is “one” with the tooth after bonding in, that it is well supported, and occlusal forces are transmitted to the underlying tooth structure.

Step Five - Try the inlay for fit even after rubber dam placement. It might be a good idea to isolate more than the tooth under consideration else the clamp may interfere with complete inlay seating.

Step Six - Prepare the undersurface of the inlay: Microabrade it with aluminium oxide or roughen with a medium grit diamond bur. Etch with phosphoric acid gel for 30 seconds. Take care to see that the etchant does not touch the extenal surfcaces of the inlay. Wash and dry. Apply an extemely thin layer of unfilled bonding resin onto the undersurface. DO NOT cure this layer.

Step Seven - Select a shade of Dual Cured composite luting agent for sealing the inlay into the tooth, according to the modifications in shade desired if any. It is easier to darken an inlay by using an appropriate shade of luting agent than to lighten it. If the components of the luting composite are dispensed onto a mixing pad, be sure to cover it with an opaque item else it will cure prematurely with the operatory light.

Step Eight - Clean the tooth preparation with pumice and water. Etch the preparation with phosphoric acid (37%) for 15 to 20 seconds. Wash and dry; do not dessicate the tooth. A shiny film of moisture should be visible all over the preparation. This is a requirement of the currently available bonding agents. Follow this up with the application of the bonding agent available to you. Adhere to the manufacturer’s instructions rigidly.

Step Nine - Once the bonding steps are completed, mix the luting agent components well without incorporation of air into the mix. The luting agent can be applied to the undersurface of the inlay in as even a layer as possible. Seat the inlay into the tooth with gentle pressure on the occlusal surface with a ball burnisher. The excess cement on the margins can be quickly removed with a brush or a tiny cotton swab, all the time keeping the pressure on the inlay to avoid unseating of the inlay. An assistant can keep the pressure on the inlay while you can pass a floss through the interprpximal region to remove excess cement from that area. This will eliminate the need to gind off all the excess later.

Step Ten - Light cure each aspect of the restoration for one minute. This will seal the margins of the restoration, leaving the remaining internal cement to cure by the self curing mechanism.

PHASE FOUR - FINISHING AND POLISHING

Step One - Trim all excess cement with finishing burs of your choice.

Step Two - Check occlusion and adjust wherever necessary with the trimming burs.

Step Three - The interproximal finishing can be done with trimming and polishing strips or with a Profin polishing system. The latter system comprises a unique handpiece with its “burs” moving to and fro in an axial direction instead of a rotary fashion. Appropriate tips designed for trimming and polsihing make interproximal finishing easy.

Step Four - Finally polish the restoration to a high shine using your favourite composite polishing system.

BEFORE AFTER IMAGE OF A LOWER SECOND MOLAR COMPOSITE INLAY

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