Scaling Practice

The Big Picture

Upper arch = chin always faces UP, head tilted BACK.

Lower arch = chin always TOWARDS chest.

Anterior teeth = you only ever sit at 12 o'clock (averted) or 8 o'clock (facing). 8–9 o'clock for the inner facing exception.

Upper posterior = almost always 1 o'clock. Only exception is mesials of 14/15/16 where you can shift to 9–10 o'clock.

Decoding Mesio/Disto to Facing/Averted (Anterior)

Patient's right side teeth (11, 12, 13, 41, 42, 43):

Mesial = averted (12 o'clock). Distal = facing (8 o'clock).

Patient's left side teeth (21, 22, 23, 31, 32, 33):

Mesial = facing (8 o'clock). Distal = averted (12 o'clock).

Why: facing means the half of the tooth angled towards your 8 o'clock chair. On the patient's right, the distal half is closer to you. On the patient's left, the mesial half is closer to you.

Anterior Seating Rules

Averted surface = 12 o'clock, always.

Facing labial surface = 8 o'clock.

Facing inner surface (palatal/lingual) = 8–9 o'clock.

Facing means the half of the tooth that turns towards your chair. Averted is the half turned away.

Anterior Head Position

Upper averted/facing labial & averted palatal = head back, chin up, midline of face centred at 12 o'clock.

Upper facing palatal (the exception) = raise the patient up, head tilted away from operator.

Lower averted/facing labial & averted lingual = chin to chest, midline at 12 o'clock.

Lower facing lingual (the exception) = chin to chest, head rotated towards operator.

Posterior Seating Rules

Sextant 1 (upper right, 14–18) buccal & palatal = 1 o'clock.

Sextant 3 (upper left, 24–28) buccal & palatal = 1 o'clock.

Sextant 4 (lower left, 34–38) buccal = 10–11 o'clock. Lingual = 9–10 o'clock.

Sextant 6 (lower right, 44–48) buccal = 8–9 o'clock. Lingual = 10–11 o'clock.

Memory hook: lingual sextant 4 = 9–10. Lingual sextant 6 = 10–11. Don't mix them up.

Posterior Head Position (Lower Arch)

Always chin down, but the rotation flips depending on what surface you want to see.

Sextant 4 buccal = head rotated TOWARDS operator.

Sextant 4 lingual = head rotated AWAY from operator.

Sextant 6 buccal = head rotated AWAY from operator.

Sextant 6 lingual = head rotated TOWARDS operator.

Simple rule: rotate the patient's head so the surface you want comes into view.

Posterior Head Position (Upper Arch)

For sextant 1 and sextant 3, head is back, chin up, tilted AWAY from operator. The away-tilt opens up access for your hand even though you can't see directly, which is why the mirror is doing the seeing.

Vision Rules

Outer surfaces (labial / buccal) = mostly direct vision.

Inner surfaces (palatal / lingual) = mostly indirect vision.

Exception: Sextant 1 buccal is INDIRECT (head tilts away, you can't see directly). Sextant 3 buccal stays direct.

Mirror's Job (5 categories)

Retract lip = any labial surface, anterior or alternative.

Retract cheek = any buccal surface, posterior. (S3 buccal, S4 buccal, S6 buccal.)

Retract / deflect tongue = any lingual surface where the tongue is in the way. (Anterior averted lingual, S4 lingual, S6 lingual.)

Indirect vision = the mirror is your eyes. (S1 buccal, S3 palatal, anterior averted palatal.)

Indirect vision and reflect light = mirror sees AND throws light onto the surface. (S1 palatal, anterior facing palatal, anterior facing lingual.)

The Only Alternative You Need

If you're asked specifically about the mesio-buccal of 14, 15, or 16 (alternative), you shift from 1 o'clock to 9–10 o'clock. Head stays back and tilted away. This gives direct vision with lip retraction (the mirror retracts the upper lip). Finger rest is extra-oral, side of cheek.

If they just say "buccal of 14/15/16" without specifying alternative, use the standard 1 o'clock position with indirect vision.

Finger Rest (Anterior)

Upper averted labial = extra-oral, side of cheek.

Upper averted palatal = intra-oral, two teeth away (specifically Q2 molars).

Upper facing labial = extra-oral, side of cheek.

Upper facing palatal = intra-oral, two teeth away (specifically 16 to 14 occlusal).

Lower averted labial = extra-oral, side of cheek.

Lower averted lingual = intra-oral, two teeth away (around 35).

Lower facing labial = no rest or side of cheek.

Lower facing lingual = extra-oral or intra-oral, two teeth away (47/46).

Finger Rest (Posterior)

Sextant 1 buccal & palatal = extra-oral, chin cupping.

Sextant 3 buccal & palatal = extra-oral, side of cheek.

Sextant 4 & 6 buccal = extra-oral, side of cheek.

Sextant 4 lingual = cross arch (rest on 46/47).

Sextant 6 lingual = cross arch (rest on upper Q2).

Pattern: upper arch is mostly extra-oral chin or cheek rests. Lower lingual = cross arch (rest on the opposite side of the same arch). Lower buccal = extra-oral.

Stroke Rule (All Anterior)

Start at the midline of the tooth, pull OUTWARD towards the line angle on your side. Never cross the midline. When you reach the other half, you're now on a different surface category, so reposition.

Quick Decode Test

You hear "averted labial 23" → averted = 12 o'clock → upper = head back chin up → labial = direct vision retract lip → done.

You hear "buccal 46" → sextant 6 buccal = 8–9 o'clock → lower = chin down → away from operator → direct vision retract cheek → done.