Restoring Primary Molars Quiz

Restoring Primary Molars

• Placing deep anatomy in primary teeth (like grooves) can weaken the restoration, leading to fracture.
• Steps of Preparation and Restoration
  • Begin burnishing after the amalgam has started to set.
  • Use a small, round burnisher to create a satin-like appearance.
  • Smoothing the surface reduces finishing time and creates a substructure with fewer voids.
  • Use a wet cotton pellet to smooth the burnished amalgam (optional).
  • Remove the rubber dam and check occlusion.
  • Rinse the oral cavity and massage the soft tissue around the previously clamped tooth.

Common Errors in Class I Amalgam Restorations

• Preparing the cavity too deep.
• Undercutting the marginal ridges.
• Carving the anatomy of the amalgam too deep.
• Not removing amalgam flash from cavosurface margins.
• Undercarving, which leads to subsequent fracture of amalgam from hyperocclusion.
• Not including all susceptible fissures.

Class II Amalgam Restorations

• Guidelines for the occlusal portion of the preparation are the same as for Class I restorations.
• Proximal Box:
  • Should be wider at the cervical portion than at the occlusal portion.
  • The buccal, lingual, and gingival walls should all break contact with the adjacent tooth, allowing for explorer tip passage.
  • Buccal and lingual walls should form a 90-degree angle with the enamel
  • The gingival wall should be flat and not beveled. All unsupported enamel should be removed.
  • Ideally, the axial wall should extend 0.5 mm into dentin and follow the outer proximal contour of the tooth.
  • The axiopulpal line angle is routinely beveled or rounded.
  • No buccal or lingual retentive grooves should be placed in the proximal box.
  • The mesiodistal width of the ging seat should be 1 mm.

Class II vs. SSCs

• Many practitioners limit Class II amalgam restorations to relatively small two-surface restorations in primary teeth.
• Three-surface (MOD) restorations may be done, but studies show SSCs (stainless steel crowns) are more durable and predictable.
• Messer and Leveringl's study shows that SSCs placed in children 4 years old and younger had a success rate twice that of Class II amalgams for up to 10 years of service.
• Roberts and Sherriff's study reported that after 5 years, one-third of Class II amalgams placed in primary teeth had failed or required replacement, whereas only 8% of SSCs required retreatment.
• SSCs are preferred for large proximal carious lesions in preschool children due to their durability.
• Amalgam may be suitable for similar lesions in teeth within 2 or 3 years of exfoliation, considering the shorter anticipated lifespan.

Steps of Preparation and Restoration (Class II)

• Administer appropriate local anesthesia and place a rubber dam.
• Place a wooden wedge interproximally, retracting the gingival papilla during instrumentation, preventing cutting of the interseptal rubber dam material and underlying gingiva, and creating prewedging for a tight proximal contact of the final restoration.
• Prepare the occlusal outline form at an ideal depth using a No. 330 bur (high-speed).
• Prepare the proximal box, starting at the marginal ridge by brushing the bur (bucco-lingually) in a pendulum motion and in a gingival direction at the dentinoenamel junction.
• Continue until contact is broken between the adjacent tooth and the gingival wall, and the wedge is visible.
• The widest bucco-lingual width of the box will be at the gingival margin.
• If the gingival wall is made too deep, the cervical constriction of the primary molar will create a very narrow gingival seat.
• Remove any remaining caries.
• Round the axiopulpal line angle slightly.
• Remove the wedge and place a matrix band.
• Reinsert the wedge between the matrix band and the adjacent tooth, beneath the gingival seat of the preparation, while holding the matrix band in place.
• Triturate the amalgam. Add the amalgam to the preparation in single increments, beginning in the proximal box, using an amalgam carrier.
• Condense the amalgam into the corners of the proximal box and against the matrix band to ensure a reestablishment of a tight proximal contact, using a small condenser. Continue filling and condensing until the entire cavity is overfilled.
• Use a small round burnisher to begin the initial contouring of the amalgam. Carve the occlusal portion with a small cleoid-discoid carver, as in Class I restorations.
• The marginal ridge can be carved with the tip of an explorer or with a Hollenback carver.
• Remove the wedge and the matrix band by drawing the band in a bucco-lingual direction.
• Remove excess amalgam at the buccal, lingual, and gingival margins using an explorer or Hollenback carver.
• Gently floss the interproximal contact to check the tightness of the contact, check for gingival overhang, and remove any loose amalgam particles from the interproximal region.
• Perform a final burnish and apply a wet cotton pellet for final smoothing (if necessary).
• Remove the rubber dam.
• Check the occlusion.

Matrix Application

• Place matrices for proximal restorations to restore normal contour, maintain normal contact, and prevent the extrusion of restorative material into gingival tissue.

Matrix Types

• T-band
• Sectional matrices (strip-T)
• Automatrix
• Tofflemiere matrix

Class I & II Preparation

• If a resin-modified glass ionomer (RMGI) liner is to be used, it should be placed and cured before the etchant.
• Etch for 15-20 seconds using an acid gel.
• Thoroughly rinse the etchant from the tooth, then apply and cure a dentin bonding agent.
• Polymerize no more than 2 mm of composite at one time.

Back-to-Back Class II Resin-Based Composite Restorations

• Place two matrix bands, then etch and bond both preparations.
• Completely fill, contour, and polymerize one of the restorations.
• After the first restoration is polymerized, use a small ball burnisher to burnish the matrix band against the newly placed restoration in the area where you want to create the contact point, ensuring a tight contact between the two restorations.
• Add, contour, and polymerize the resin-based composite material in the second preparation.
• Remove the wedge and bands, and finishing and polishing procedures are identical to single restoration placement.

Restoration of Primary Incisors and Canines

• Indications:
  • Caries
  • Trauma
  • Developmental defects of the tooth’s hard tissue

Class III Adhesive Restorations

• Very challenging due to subgingival extension, which makes isolation and hemorrhage control difficult, and large pulp size, which requires small preparations.
• A simple slot preparation removes decay and has a short cavosurface bevel.
• Retention is gained through:
  • Acid etching.
  • Retentive locks on the facial or lingual surface, especially important in children with bruxism.
  • Beveling the cavosurface margin to increase the surface area of enamel etched.
  • Preparing the entire facial surface by 0.5 mm and veneering the surface.

Class III Restorations in Primary Canines

• Slightly different preparation from that for incisors.
• Proximal box is directed at a different angle toward the gingiva.
• Either amalgam or adhesive materials may be used.
• The preparation (except for a short cavosurface bevel for resins) is identical regardless of the restorative material chosen.
• A dovetail can be placed on the facial surface, except for amalgam in a maxillary canine, where it is placed on the palatal surface.

Modified Class III Cavity Preparation

• Uses a dovetail on the lingual or labial surfaces of the tooth.
• Lingual lock is used for maxillary canines.
• Labial lock is used for mandibular canines (aesthetic requirement is not as important).
• Dovetails allow for additional retention and access to properly insert the restorative material.

Clinical Steps (Class III)

• Administer appropriate anesthesia.
• Place the rubber dam. Ligation of individual teeth with dental floss provides the best stability.
• Place a wooden wedge interproximally.
• Create access and remove caries using a No. 330 bur or No. 2 round bur (high-speed), using a facial access.
• Ideally, the axial wall should be placed 0.5 mm into dentin. Use a round bur (low-speed) to remove deep decay
• The gingival and lingual walls should just break contact with the adjacent tooth.
• It is not necessary to break contact with the incisal wall of the preparation to maintain adequate tooth structure.
• To enhance retention, place a dovetail or lock on the labial or lingual surface. The dovetail should not extend more than halfway across the labial surface and should be in the middle horizontal third of the tooth. It may extend across the cervical area if decalcification is present.
• Place a short bevel (0.5 mm) at the cavosurface margin using a fine, tapered diamond or a flame-shaped composite finishing bur.
• Clean and dry the preparation with water and compressed air.
• Place a plastic or sectional metal matrix, cut in half horizontally, interproximally.
• Reinsert a wedge.
• Etch for 15-20 seconds.
• After etching, rinse and dry the preparation well. (This step is eliminated if using a self-etching bonding agent.)
• Place a dentin-bonding agent. Gently blow compressed air into the preparation to disperse a thin layer of bonding agent evenly over dentin and enamel.
• Polymerize the bonding agent.
• Place the composite in the preparation using a plastic instrument or a pressure syringe. Pull the matrix tightly around the cavity preparation with finger pressure and hold until cured.
• Hold the visible light as close as possible to the composite and polymerize according to the manufacturer's instructions.