1. Classification
   1. Vertical dimension at rest (VDR)
      1. The length of face when mandible is in rest position
         1. VDR = VDO + FreeWay space
   2. Vertical dimension at occlusion (VDO)
      1. The length of face when the teeth are in contact in MIP (Maximum intercuspation)
   3. Physiological rest position
      1. The postural position of mandible when individual is resting comfortably with upright position & associated muscles are in a state of minimal contractual activity
2. Methods of recording VDR
   1. Facial measurements after swallowing
      1. Can be done by :- ▪︎Marking 2 points - 1 at tip of nose & other on the chin. Hence vertical distance btw 2 points can be measured using a divider/scale ▪︎Willis gauge can be used ▪︎Dakometer ▪︎Boley gauge
   2. Tactile sensation
   3. Anatomical landmarks
      1. Willis guide - states that distance from pupil of eye to Rima oris (corner of mouth) [B] should be equal to distance from anterior nasal spine to lower border of mandible [A]
   4. Speech
   5. Facial expressions
3. Methods of recording VDO
   1. Mechanical methods
      1. RIDGE RELATIONS
      2. 1) Distance of incisive papilla to mandibular central incisor edge
      3. 2) Parallelism of ridges
      4. PRE-EXTRACTION RECORD
      5. a) Profile photographs
      6. b) Profile radiographs
      7. c) Profile silhouettes
      8. d) Profile tracing
      9. e) Articulated casts
      10. f) Facial measurements
   2. Physiological methods
      1. a) Physiological rest position
      2. b) Phonetics
      3. c) Esthetics
      4. d) Swallowing threshold
      5. e) Tactile sense
      6. f) PowerPoint
      7. g) Wax occlusal rims
      8. h) Cephalometry
   3. EFFECTS OF VERTICAL DIMENSION (VD)
      1. Effects of Increased VD
         1. Effects of Decreased VD
      2. ▪︎Discomfort to patient
         1. ▪︎Reduced masticatory efficiency
      3. ▪︎Clicking of teeth during speech
         1. ▪︎Poor esthetics
      4. ▪︎Pain & clicking in TMJ
         1. ▪︎Angular chelitis
      5. ▪︎Difficulty in swallowing
         1. ▪︎Pain in TMJ
      6. ▪︎Loss of freeway space
         1. ▪︎Prognathism
      7. ▪︎Speech problems
         1. ▪︎Decreased lower facial height
      8. ▪︎Stretching of facial muscles
         1. ▪︎Decreased space of oral cavity
4. OTHER KEY PONITS
   1. ▪︎Pure hinge movements of mandible occur in - Terminal Hinge position ▪︎Hinge movt is produced by action of Lateral pterygoid & suprahyoid muscles & is aided by gravity ▪︎Rest position of mandible is governed by - tone of Elevator muscles & Gravity
   2. Difference between :-
      1. CLOSED SPEAKING SPACE
         1. FREEWAY SPACE/INTEROCCLUSAL SPACE
      2. ▪︎Described by Silverman
         1. ▪︎Described by Thompson & Niswonger
      3. ▪︎Measures VD when mandible & muscles involved in function of speech. It's the space btw upper & lower teeth when sounds like "s", "j", "ch", are pronounced
         1. ▪︎It establishes VD when mandible & muscles are in rest position. ( FREEWAY SPACE = VDR - VDO ) where, VDR - Vertical dimension at rest VDO - Vertical dimension at occlusion
      4. ▪︎Dynamic position when muscles are in state of function
         1. ▪︎Static position when muscles are in state of rest
      5. ▪︎It's about 1-2mm when measured in premolar area
         1. ▪︎It's about 2-4mm when measured in 1st Premolar area
      6. ▪︎Speaking spaces increases when VD is small
         1. ▪︎Freeway space increases with reduced VD