SHAPING LARGE RESTORATIONS
Quite often a large restoration with few anatomical references takes an inordinate amount of time to shape after removing the band.This is a disincentive to placing these restorations. Proficiency must be developed to become a master of this modality. The following tips should increase clarity and enhance speed.
SEQUENCE OF STEPS IN DEVELOPING CONTOUR
- Presumably the band has been bent properly and there is bulk in all the required areas, and you now just need to reduce excess contour. See Bandbender
- Typically, with a Tofflemire band, the occlusal table is too large and the buccal and lingual walls are excessively divergent.
- Be sure that you have started the restorative process correctly, and registered the occlusal contour with Kerr Occlusal Indicator Wax and planned the shape of the restoration, noting the form of the opposing tooth and any distortions from ideal, see Preoperative Occlusal Analysis
- Be sure you have set the stage to develop ideal morphology in the restored tooth. Reshape the opposing tooth If needed, with the patient’s consent, to the extent feasible,see Occlusal Plasty. Examples are
- reduce plunger cusps which point-load the restorative if left sharp
- reduce over- erupted cusps that force marginal ridges to be uneven with respect to the height of the adjacent tooth
- harmonize irregular cusp tips, if over-eruption or wear distorts the aesthetic appearance of the buccal corridor.
- Develop the occlusal contour Start bulk-shaping the outline form, using an 1157 carbide or 1716.8C coarse tapered diamond for speedy reduction.The bur axis should be held perpendicular to the occlusal surface, reducing excess buccal and lingual contour by sweeping mesio-distally. The objective is to create an occlusal table of correct proportions and by using more aggressive rotary instruments spare the 12-bladed finishing burs from excess wear. Do not use a coarse diamond near any enamel cavosurface. Sight down the buccal and lingual corridors to reference the shape as it develops.
- Create occlusal convergence to a smaller occlusal table above the widest point of the buccal or lingual surface. Use the 7406 bur, again held in the handpiece with the vertical axis perpendiciular to the occlusal surface.
- Marginal ridge heights You should have noted preoperatively if the marginal ridges were at the same height between adjacent teeth, or if they could be if occlusal plasty was performed. See Occlusal Plasty. Now reduce the marginal ridges to correct height, using the 7406bur.
- Refine the buccal and lingual contours Once gross reduction has neared completion, switch to the 7902 bur, and improve the proximal embrasures with this same bur, and all embrasures.
- Visualize the occlusal table as a smaller version of the overall tooth silhouette, as seen from an occlusal view, set inside the outline form of the tooth.
- Develop occlusal anatomy Return to the 7406 carbide and “scribe in” central fossa, CDG and fossae.
- Create cusp arms.
- Ensure that as you create the cusp arms that the bur tip is always aimed towards the midpoint of the tooth.Visualize the central fossa as the center of a wheel and the cusp inclines as spokes radiating out from that center. This will angle the cusp arms correctly. Do not allow the cusp arms to extend all the way to the outline form; stop the arms short at the periphery of the occlusal table.
- Lingual and Buccal silhouette With a mirror in the buccal or lingual vestibule, assess the tooth as a silhouette from the buccal and lingual.
- Detail cusp separation: If the cusp arms are not sufficiently separated, use the 7902 to deepen the buccal or lingual grooves and thereby separate the cusps. Don’t use the 7406 : it is too large and bulky, cuts too quickly, and will create crude anatomy.
- Remove dam and check occlusion. If occlusion is sub, more resin can be added by following a Composite-to-Composite Bonding protocol,
- Sandblast the surface needing augmentation see Sandblasting
- place bonding agent, blow thin and cure. This will no work with S/E Adhesives.See Standard Bonding Protocol
- Place additional heated resin see Heated Resins using the Hufriedy H27/29 lubricated with ethanol see Ethanol Instrument Lubrication to avoid pull-back and to
- Cover the increment with Zest Danville Liquid Lens, and instruct the patient to bite into occlusion. and curing with the curing tip from a buccal access until hardened.
- Then have the patient open cure fully to full normal cure time See Curing Resins
- Check for flash using caries detector See Caries detector to avoid flash, voids,bubbles and irregulaities
- Repair any voids, bubbles or deficiencies. See Fixing Voids and Bubbles
- Round, polish and unify with FG brownie points used wet FG Shofu Brownie minipoints See Polishing with Shofu Brownie