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.

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 — that's 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

Anterior labial = retract the lip (upper lip, lower lip, or general soft tissue).

Posterior buccal = retract the cheek.

Anterior averted palatal = indirect vision only.

Anterior facing palatal = reflect light onto the surface.

Anterior averted lingual = deflect the tongue.

Anterior facing lingual = protect the tongue and reflect light.

Posterior lower lingual (S4) = retract the tongue.

Posterior lower lingual (S6) = retract the tongue, indirect vision for the distals.

Sextant 1 palatal = indirect vision and reflect light.

Sextant 1 buccal = the mirror is your eyes (indirect vision to see).

Sextant 3 palatal = indirect vision only.

The Only Alternative You Need

When working on the mesio-buccal of 14, 15, or 16, you may shift from 1 o'clock to 9–10 o'clock. This gives direct vision with lip retraction. Either answer is accepted in the quiz.

Finger Rest (Anterior)

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

Upper averted palatal = quadrant 2 molars.

Upper facing labial = extra-oral.

Upper facing palatal = 16–14 occlusal.

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

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

Lower facing labial = no rest or side of cheek.

Lower facing lingual = extra-oral or intra-oral on 47/46.

Finger Rest (Posterior)

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

Sextant 3 buccal = extra-oral, left cheek.

Sextant 3 palatal = extra-oral.

Sextant 4 & 6 buccal = extra-oral.

Sextant 4 lingual = cross arch 46/47.

Sextant 6 lingual = cross arch 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.