What does MOD stand for in dentistry?

Mesial, Occlusal and Distal — three surfaces of a single tooth. It is three surface codes written together, not an abbreviation of a word.

What is the difference between MO, DO and MOD?

All three include the occlusal surface. MO adds the mesial surface, DO adds the distal surface, and MOD includes both — so MOD spans the tooth from the front proximal surface, across the chewing table, to the back proximal surface.

Can an incisor have a MOD?

No. The O stands for occlusal, and only premolars and molars have an occlusal surface. On an incisor or canine the equivalent involves the incisal edge and would be written with an I, such as MID.

Does MOD tell you what treatment was done?

No. MOD names surfaces only. It says which faces of the tooth are involved, not what was found there or what was done about it. The rest of the chart entry carries that.

What does MOD mean in dentistry?

MOD is not a word. It is three tooth surface codes written together: Mesial, Occlusal and Distal.

MOD describes three surfaces of one posterior tooth: the mesial surface facing the midline, the occlusal chewing table on top, and the distal surface facing the back of the mouth. Written after a tooth number — #19 MOD — it says those three surfaces of that one tooth are involved.

Because the O is the occlusal table, MOD only applies to premolars and molars. Anterior teeth have an incisal edge instead.

Schematic view from above. Mesial is drawn left and distal right on every tooth; on a real chart, which side faces the midline depends on the quadrant.

The three letters

Letter	Surface	Where it is
M	Mesial	The proximal surface facing toward the midline of the face.
O	Occlusal	The chewing surface on top. Premolars and molars only.
D	Distal	The proximal surface facing away from the midline.

MO, DO and MOD

The related combinations differ only in how many proximal surfaces join the occlusal table. Select any to open it in the decoder.

MO

Schematic view from above. Mesial is drawn left and distal right on every tooth; on a real chart, which side faces the midline depends on the quadrant.

Mesio-occlusal — the mesial surface and the chewing table.

Try #19 MO

DO

Schematic view from above. Mesial is drawn left and distal right on every tooth; on a real chart, which side faces the midline depends on the quadrant.

Disto-occlusal — the distal surface and the chewing table.

Try #19 DO

MOD

Schematic view from above. Mesial is drawn left and distal right on every tooth; on a real chart, which side faces the midline depends on the quadrant.

Mesio-occluso-distal — both proximal surfaces and the chewing table.

Try #19 MOD

What MOD does not tell you

MOD is a location, not a finding and not a procedure. It names which faces of the tooth are in scope. It does not say what condition was present, what material was used, or what was done — that information sits elsewhere in the chart entry. Reading a surface code as a treatment is the most common misreading of dental notation.

Common questions

What does MOD stand for in dentistry?: Mesial, Occlusal and Distal — three surfaces of a single tooth. It is three surface codes written together, not an abbreviation of a word.
What is the difference between MO, DO and MOD?: All three include the occlusal surface. MO adds the mesial surface, DO adds the distal surface, and MOD includes both — so MOD spans the tooth from the front proximal surface, across the chewing table, to the back proximal surface.
Can an incisor have a MOD?: No. The O stands for occlusal, and only premolars and molars have an occlusal surface. On an incisor or canine the equivalent involves the incisal edge and would be written with an I, such as MID.
Does MOD tell you what treatment was done?: No. MOD names surfaces only. It says which faces of the tooth are involved, not what was found there or what was done about it. The rest of the chart entry carries that.

Read a full expression

Decode #19 MOD