Cavity Classification & Nomenclature PDF

Chapter 2 CAVITY CLASSIFICATIONS 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 dentin-pulp organ (DPO) and the periodontium.  Inc...

Chapter 2 CAVITY CLASSIFICATIONS 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 dentin-pulp organ (DPO) 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 cavity preparation is the surgical procedures followed to eliminate the lesion in the hard tooth structure, prevent spread of infection and establish compatible foundation for the restoration. The cavity preparation should be given a form that will assure proper retention for the restorative material, adequate resistance to fracture during function, immunity from recurrence of caries at the margins of restoration and protection for vital pulp. Classification of cavities: 1. Anatomical classification: Considering the areas of liability to dental caries, cavities can be classified into:  Pits and fissures cavities.  Smooth surface cavities. 2. Black’s classification: The classification devised by G.V. Black, which is based upon 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. Black classified cavities into five classes: Class I Cavities: Pit and fissure lesions occur in the occlusal surface of molars and premolars, the occlusal two-third of the buccal and lingual surfaces of molars 1|Page  and in the palatal surfaces of upper anterior teeth (most frequently in lateral incisors, less frequently in central incisors and rarely in canines). Class II Cavities: Smooth surfaces lesions that occur in the proximal surfaces of posterior teeth, i.e. mesial or distal surfaces of molars and premolars. Class III Cavities: Smooth surface lesions occur in the proximal surfaces of anterior teeth, i.e. mesial and distal of incisors and canines (cuspids); but do not include the incisal angle. Class IV Cavities: Smooth surface lesions that originate on the proximal surfaces of anterior teeth, but caries is so extensive that the incisal angle is involved. Class V Cavities: Smooth surface lesions occurring in 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 cavity. 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. 2. Numerical classification: Cavities may be classified according to the number of surfaces involved into:  Simple cavities: These are cavities occurring in one surface only, e.g. simple occlusal (O), simple buccal(B), simple mesial(M), etc.  Compound cavities: These are cavities involving two surfaces, e.g. occluso-mesial(OM) , occluso-buccal(OB),disto-lingual(DL), mesio- palatal(MP), etc.  Complex cavities: These are cavities involving more than two surfaces e.g. mesio-occluso-distal(MOD), occluso-bucco-lingual(OBL), mesio- bucco-palatal(MBP), 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. 2|Page 3. ICDAS (international caries detection and assessment): Based on the severity of the lesion 3|Page  4. Mount and Hume Classification (Si/Sta Classification): This cavity classification is based on the new concept of minimal intervention. The proposed classification is based on the fact that there are only three surfaces of the crown of a tooth that can be subjected to caries attacks. However, this classification also takes into consideration the size of the lesion. Thus, it is a combination of the Site and Stage of the defect and hence the name Si/Sta classification. The sites involved are: Stage 0 Stage 1 Stage 2 Stage 3 Stage 4 Initial lesion Smallest minimal lesion Moderate-sized cavity; The cavity needs to be Extensive cavity, ex; identified but not requiring operative there is still sufficient modified and enlarged to loss of cusp from a yet cavitated. It can intervention. The cavity is sound tooth structure provide some protection posterior teeth or an possibly be into dentin just beyond to maintain the for the remaining tooth incisal edge from an remineralized healing through integrity of the tissues from the occlusal anterior teeth. remineralization. remaining crown. load. Site 1 1.0 1.1 1.2 1.3 1.4 Pits and fissures on the occlusal surfaces of posterior teeth Site 2 2.0 2.1 2.2 2.3 2.4 Contact areas between any pair of teeth, anterior or posterior Site 3 3.0 3.1 3.2 3.3 3.4 Cervical areas related to gingival tissues including exposed root surfaces. Cavity Preparation Nomenclature: The Enamel Wall: It is that portion of a prepared cavity, which consists of enamel. It includes the thickness of the enamel from the dentino-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 dentino-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 4|Page cavity is usually in enamel. However, in cavities found in the root of teeth, the cavosurface 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 surrounding walls of a prepared cavity take the name of the tooth surface that the wall is toward. For example, the wall towards the buccal surface is called the buccal wall and that towards the lingual surface is termed the lingual wall. Rule II: The wall of a prepared cavity, which is occlusal of the pulp, and in a plane at right angle to the long axis of the tooth, is called 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. D.Mai Mamdouh Conservative and Restorative Dentistry Department 5|Page