Class III Preparation in Dentistry

Proximal Caries Restoration

• Anaesthesia is usually necessary for patient comfort and to decrease salivary flow during the procedure
• The restoration involves selecting the composite shade before the tooth is dehydrated and lightened
• The area must be isolated to permit effective bonding

Class III Preparation

• The preparation is initiated from a lingual approach using a round bur instrument
• The bur is positioned for entry and rotated at high speed using air-water spray
• The point of entry is located within the incisogingival dimension of the lesion or defect and as close to the adjacent tooth as possible
• The cutting instrument is directed perpendicular to the enamel
• Incorrect entry overextends the lingual outline and unnecessarily weakens the tooth

Composite Restoration

• Place composite into the most facial portion of the preparation, beginning at the facial-axial line angle
• Increments of composite should be no more than 2mm thick
• Use the index finger to hold down on the facial portion of the mylar strip and wrap the lingual portion over the lingual contour of the tooth to create the proximal anatomy

Finishing and Polishing

• Remove gross excess material or overhang as needed
• Use the more abrasive side of the finishing strip to reduce interproximal excess
• Insert the finishing strip by the grit-free middle portion and move it buccally and lingually to contour and smooth
• Do not use the finishing strip in the contact area
• Use a No. 12 surgical blade or scaler to remove interproximal excess material in the gingival area

Cavity Preparation and Removal

• Remove caries until all infected dentin has been removed
• When breaking the proximal wall, use a wedge guard or a metal matrix to protect the adjacent tooth
• Protect the external fluoride-rich layer to avoid the increased possibility of caries
• Full interproximal clearance is not mandatory for Class II cavities

Matrix and Wedges

• Use a wedge guard or a metal matrix to protect the adjacent tooth
• A margin separation technique can simplify matrix band insertion and work for minor interproximal beveling
• Placing a wedge to separate the tooth and a matrix band may be all that is necessary
• Another possibility is to pre-separate the teeth by placing a ring in advance of the cavity preparation

Class II Cavity

• When caries approaches the gingival margin, the supragingival protocol should be employed
• Minimally invasive removal of caries and old restorations and enamel preservation techniques will make restoring easier, more predictable, and healthier for the periodontium
• Remove the sharp external cavosurface margin throughout, to remove loose enamel rods and enhance adhesion using a flame diamond

Essential Burs

• Very small-diameter flame bur (FG; 006–008): used for conservative opening of suspect grooves
• Cylindric bur with rounded head (FG; 007–0014): used for most Class 1 and 2 cavity preparations
• Tungsten carbide rosehead bur (CA; 010–020): used to remove infected dentin
• Fine-grained flame bur (FG; 010): used to finish Class 2 box walls
• Arkansas stone (FG): used to smooth the cavity margin
• Brownie polisher (CA): used to polish the cavity margin