G.V. Black's classification sorts carious lesions (and the restorations that fix them) by location. It's used in charting and in nearly every operative procedure you'll assist on, so it's worth knowing cold.
The six classes
- Class I: pits and fissures. Occlusal surfaces of premolars and molars, buccal or lingual pits of molars, lingual pits of upper incisors.
- Class II: proximal surfaces of premolars and molars. The classic MO, DO, or MOD.
- Class III: proximal surfaces of incisors and canines that do not involve the incisal angle.
- Class IV: proximal surfaces of incisors and canines that do involve the incisal angle. A chipped corner that gets rebuilt.
- Class V: the gingival third of the facial or lingual surface of any tooth. Root caries and abfraction lesions live here.
- Class VI: cusp tips of posterior teeth and incisal edges of anterior teeth. Added after Black's original five.
Remembering them
Ask two questions: is it a front tooth or a back tooth, and where on the tooth is the decay?
- Back tooth, chewing surface: Class I
- Back tooth, between the teeth: Class II
- Front tooth, between the teeth, corner still there: Class III
- Front tooth, between the teeth, corner broken off: Class IV
- Any tooth, near the gumline on the cheek or tongue side: Class V
- Any tooth, on the cusp tip or biting edge: Class VI
In a chart note, the class tells the team what to set up. A Class II needs a matrix band and wedge, because the wall between the teeth has to be rebuilt. A Class V on the facial usually doesn't.