• When determining excursion path of a cusp, what are we looking for specifically?

In working side lateral excursion, what is the movement of

• Mandibular posterior
• Maxillary posterior

In non-working side lateral excursion, what is the movement of

• Mandibular posterior
• Maxillary posterior

In protrusion, what is the movement of

• Mandibular over maxilla
• Maxilla over mandibular

In working side lateral protrusion, what is the movement of

• Mandibular posterior
• Maxillary posterior

In non-working side lateral protrusion, what is the movement of

• Mandibular posterior
• Maxillary posterior

Steps

1. Determine the movement side: working vs non-working → left vs right

2. Determine the opposite tooth/teeth → occlusal anatomy → possible grooves & cusps

3. Determine the MICP position of the cusp on the opposing tooth

   → If mesial supporting cusp of maxilla ⇒ central groove (stay in opposite occlusal surface)

   → If distal supporting cusp of maxilla ⇒ embrasure (move into the occlusal surface of adjacent tooth)

   → If distal supporting cusp of mandible ⇒ central groove (stay in opposite occlusal surface)

   → If mesial supporting cusp of mandible ⇒ embrasure (move into the occlusal surface of adjacent tooth)

4. Determine protrusive direction OF THE MICP POSITION

5. Determine lateral excursion direction OF THE MICP POSITION

   ⇒ Determine lateral protrusive excursion direction, if applicable

   <aside> 💡 If the cusp in question is on the mandible → normal direction (follow jaw movement) If the cusp in question is on the maxilla → invert direction (if normal is mesial → inverted is distal)

   </aside>

6. Determine the possible path: following grooves or crossing incline plane of opposing cusp.

   → Movement direction = name of opposing cusp being crossed if there are only 4 cusps (MF, ML, DF, DL)

   → Inverted movement direction = name of incline plane being crossed (e.g. DF direction = ML incline plane)

   If looking for excursion of incisal edges → anterior guidance

   If looking for excursion of canine cusps → canine guidance

Example: ML cusp of # 14 - NW lateral protrusive excursion

1. NW side of #14 → right side movement

2. Opposing tooth = # 19 → 5 cusps (D cusp), central groove, MF groove, DF groove L groove

3. MICP position of ML cups of #14 → mesial supporting cusp of maxilla → central groove

4. Protrusive direction → distal (#14 is on maxilla, invert of mesial)

5. Lateral direction → facial (#14 is on maxilla, invert of lingual)

   ⇒ Lateral protrusive direction→ DF