Dental Caries and Nomenclature PDF

Cavity Classification and Nomenclature A cavity is a defect in the hard tooth structure resulting from an insult to the dental tissues. This cavitation induces several adverse effects, including: Irritation to the pulp-dentin organ and the periodontium. Increased food stagnation and...

Cavity Classification and Nomenclature A cavity is a defect in the hard tooth structure resulting from an insult to the dental tissues. This cavitation induces several adverse effects, including: Irritation to the pulp-dentin organ and the periodontium. Increased food stagnation and plaque retention. Increased vulnerability to fracture of the remaining tooth structure. Disturbance of the occlusion, contact or contour. Impairment of the esthetic appearance. A prepared cavity: a bio-mechanical foundation for a restoration Classification of Cavity: 1. Anatomical classification 2. Black’s classification 3. Numerical classification 4. Mount’s classification 1. Anatomical Classification: Considering the areas of liability to dental caries, cavities can be classified into: a. Pits and fissures cavities. b. Smooth surface cavities. 2. Black’s classification: The classification devised by G.V. Black is based on the site of onset of the carious process. The same classification is used to refer to cavity preparations because the location of the carious lesion is the major factor in cavity preparation design. a. Class I Cavities: These are cavities originating in anatomical pits and fissures. They are found in the occlusal surface of molars and premolars, the occlusal two-thirds of the buccal and lingual surfaces of molars, and in the palatal surfaces of upper anterior teeth (most frequently in lateral incisors, less frequently in central incisors and rarely in canines). b. Class II Cavities: These smooth surface lesions occur in the proximal surfaces of posterior teeth, i.e. mesial or distal surfaces of molars and premolars.  c. Class III Cavities: These smooth surface cavities occur in the proximal surfaces of anterior teeth, i.e. mesial and distal of incisors and canines (cuspids); without the involvement of incisal angle. d. Class IV Cavities: These are smooth surface cavities that originate on the mesial and distal surfaces of anterior teeth, with incisal angle involvement. e. Class V Cavities: These smooth surface cavities occur on the gingival third of the buccal and lingual surfaces of all teeth, excluding cavities occurring in anatomical pits in the palatal surfaces of upper incisors, where they are grouped with class I cavities. f. Class VI Cavities: This is an additional class that has been added comprising sites not originally included in Black’s classification. These include cavities on the incisal edge of anterior teeth and the occlusal cusp heights or tips of posterior teeth. 3. Numerical classification: Cavities may be classified according to the number of surfaces involved into: a. Simple cavities: These are cavities occurring on one surface only, e.g. simple occlusal, simple buccal, simple mesial, etc. b. Compound cavities: These are cavities involving two surfaces, e.g. occluso-mesial or distal, occluso-buccal or lingual, mesio- or disto-labial, mesio-palatal, etc. c. Complex cavities: These are cavities involving more than two surfaces e.g. mesio- occluso distal, occluso-bucco-lingual, mesio-labio-palatal, etc. N.B.: Class I, II, and III may be simple, compound, or complex, while class V is always simple and class IV is always complex. N.B.: The description of tooth preparation is abbreviated by capitalizing the first letter of each tooth surface involved. For example, an occlusal tooth preparation is abbreviated (O), a preparation involving the mesial and occlusal surfaces is abbreviated (MO) and a preparation involving the mesial, occlusal, and distal surfaces is abbreviated (MOD). 4. Mount’s Classification: Only three surfaces of a tooth's crown can be affected by caries. However, this classification system also considers the size of the cavity. As a result, it combines the location and severity of the decay, leading to its name: Si/Sta classification (site and stage). Site 1: Pits and fissures on the occlusal surfaces of posterior teeth and other defects on otherwise smooth enamel surfaces. Site 2: Contact areas, anterior or posterior. Site 3: Cervical areas related to gingival tissues including exposed root surfaces. The sizes or stages that can be readily identified include: Size 0: Initial lesion at any site can be identified but not yet resulted in surface cavitation. It can possibly be healed. Size 1: Smallest minimal lesion requiring operative intervention. The cavity is into dentin just beyond healing through remineralization. Size 2: Moderate-sized cavity; there is still sufficient sound tooth structure to maintain the integrity of the remaining crown. Size 3: The cavity needs to be modified and enlarged to provide some protection for the remaining tooth tissues from the occlusal load. There is already a split at the base of the cusp, or if not protected a split will likely develop. Size 4: an extensive lesion, following the loss of cusp from a posterior teeth or an incisal edge from an anterior.  Cavity Preparation Nomenclature: The Enamel Wall: A portion of a prepared cavity, which consists of enamel. It includes the thickness of the enamel from the dentin-enamel junction to the cavosurface angle. The Dentin Wall: It is that portion of the wall of a prepared cavity, which consists of dentin. The Dentino-Enamel Junction: The dentin-enamel junction (DEJ) is the line of junction of dentin and enamel. It usually appears in the internal walls of the prepared cavities. The Cemento-Enamel Junction: The cemento-enamel junction (CEJ) is the junction of the enamel and cementum. It also is referred to as the cervical line. Cavo-Surface angle and Cavo-Surface margin: It is the angle formed by the junction of the wall of the cavity preparation with the external surface of the tooth. The actual junction is called the cavo-surface margin. The cavo-surface margin of a cavity is usually in enamel. However, in cavities found in the root of teeth, the cavo surface margin will be cementum The isthmus portion: It is the junction between two portions of a compound or complex cavity preparation, e.g. junction between occlusal and proximal portions in class II.  Walls and Angles of the cavity preparation: Rule I: The walls of a prepared cavity are named according to the tooth surface they face. For instance, a wall facing the buccal side is called the buccal wall. Rule II: The wall that is positioned occlusal to the pulp and perpendicular to the tooth's long axis is referred to as the pulpal wall. Rule III: The wall of a prepared cavity in an axial plane (parallel to the long axis of the tooth) and approximates the pulp, is called the axial wall. Rule IV: All line angles are formed by the junction of two walls along a line, and are named by combining the names of the walls joining to form the line angle. Rule V: All point angles are formed by the junction of three walls at a point, and are named by joining the names of the walls forming the point angle. N.B.: the junction of two walls is often rounded, so it does not actually form a line, but it is still referred to as a line angle; likewise, a point angle is usually not a sharp point. This is especially true in adhesive cavity designs.