Class II cavity

Date: 2015-10-07; view: 574.

Deep-seated class I cavity

If an amalgam restoration is planned, the first step in the preparation of an extensive class I cavity is to plane back the enamel that overhangs the extensive carious lesion. Then the cavity preparation should be extended throughout the remaining grooves and anatomic occlusal defects. The carious dentin should next be removed with large, round burs or spoon excavators. If a carious exposure is not encountered, the cavity walls should be paralleled and finished as previously described. With deep carious lesions and near pulp exposures, the depth of the cavity should be covered with a biocompatible base material to provide adequate thermal protection for the pulp. If a composite resin and/or glass ionomer restoration is planned, any disease-free pits and grooves may be sealed as part of the bonded restoration. The restorative material will also provide thermal insulation to the pulp.

Small Lesions.As bonded restorations have improved, especially those restorations capable of fluoride release, more conservative cavity preparation designs have also been advocated. In otherwise sound teeth free of susceptible pits and fissures, accessing small class II carious lesions via small openings in the marginal ridges or in the facial surfaces of the teeth is becoming a popular technique. Gaining access to the lesion with openings only large enough to allow caries excavation is the goal. Caries is removed by pendulous motions of small burs or by tilting of the air abrasion tip laterally and pulpally at the initial opening. This technique is particularly useful in cooperative patients with one or two affected primary molars who are judged to be at relatively low risk for additional caries activity. After conservative preparation restorations with fluoride-releasing restorative materials are recommended. Local anesthesia is usually unnecessary to make the preparation. When performing this short procedure in cooperative patients, rubber dam isolation is often optional, especially on maxillary teeth. Use of resin-modified glass ionomer materials results in excellent restorations for this conservative procedure.

Lesions with greater dentin involvement.The first step in the traditional preparation of a class II cavity in a primary tooth for an amalgam or an esthetic restoration involves opening the marginal ridge area. Extreme care must be taken when breaking through the marginal ridge to prevent damage to the adjacent proximal surface. Before application of amalgam the gingival seat and proximal walls should break contact with the adjacent tooth. The angle formed by the axial wall and the buccal and lingual walls of the proximal box should approach a right angle. The buccal and lingual walls necessarily diverge toward the cervical region, following the general con-tour of the tooth. The occlusal extension of the preparation should include any caries-susceptible pits and fissures. If the occlusal surface is sound and not caries susceptible, then a minimal occlusal dovetail is still often needed to enhance the cavity retention form. If carious material remains after the preparation outline is established, it should next be removed. The appropriate liner or intermediate base, if indicated, and a snug-fitting matrix should be placed before the insertion of the amalgam.

Restorations with esthetic adhesive materials.Because of the improvements in the properties of composite resins, many dentists use them routinely for posterior restorations. More recently the use of glass ionomer restoratives (or other materials on the glass ionomer—composite resin continuum) has also been advocated. The preparation and restoration may be similar to that described earlier for amalgam when significant caries exists on both the occlusal and proximal surfaces. However, little or no occlusal preparation may be required when the occlusal pits and fissures are caries susceptible but sound or incipient. Then the proximal restoration may be combined with application of an occlusal sealant. Whenever composite restorative materials are employed, enamel beveling, etching, and application of bonding agents are recommended. The dentist's sound professional judgment is the key to selecting the restoration that will best serve the patient in each situation.