🔹Camper’s line is the line joining the inferior border of the ala of the nose to the superior border of the tragus. Ideally, the Camper’s plane is considered to be parallel to the occlusal plane.
🔹Christensen’s phenomenon is the space that occurs between the occlusal surfaces during mandibular protrusion.
🔹Central bearing device was first described by Alfred Gysi in 1910.
🔹Interocclusal distance or freeway space is 2–4 mm which is observed in the premolar region in class I cases. In class II, it is greater than 4 mm and in class III, it is less than or equal to 1 mm.
🔹Gothic arch tracing is a device which produces a tracing resembling the arrowhead or Gothic arch during the mandibular movements.
🔹Increased vertical dimension leads to trauma to the tissues, pain in the TMJ, clicking sound of the dentures, increased facial height, tense facial muscles and difficulty in speech.
🔹Reduced vertical dimension results in reduced function of the muscles with loss of muscle tone, creases at the corner of the mouth, trauma to the TMJ, decreased facial height, lax facial muscles with ageing appearance.
🔹Vertical dimension influences the aesthetics and mechanics of the denture and if incorrect may produce possible disturbances in the TMJ.
🔹 M.E. Niswonger (1934) called the rest position as neutral position and estimated it to be 3 mm.
🔹Silverman’s closest speaking space the small amount of space between the upper and lower teeth in the anterior region.
🔹There are two types of record bases:
➡️ VDO is established by using this formula.
🔺VDO = VDR – freeway space
➡️ Freeway space as given by various authors are as follows:
🔺 M.J. Thompson: 2–3 mm.
🔺 H. Sicher: 2–5 mm.
🔺 M.E. Niswonger: 3 mm.
🔺M.A. Pleasure : 3 mm.
📌 Methods Of Determining Vertical Relations
👉 Mechanical Methods
(i) Ridge relation
🔸Distance of incisive papilla from mandibular incisors
🔸Parallelism of the ridges
(ii) Measurements of the former dentures
(iii) Pre-extraction records
🔸 Profile radiographs
🔸 Articulated casts
🔸 Facial measurements
🔸 Profile silhouettes
🔸 Profile photographs
🔸 Wright’s method
🔸 Willis method
🔸 Face mask
👉 Physiologic Methods
(i) Physiologic rest position
(ii) Phonetics and aesthetics as guides
(iii) Swallowing threshold
(iv) Tactile sense or neuromuscular perception
(v) Patient-perceived comfort
(vi) Occlusion rims
(vii) Bimeter
📌 Theories Of Centric Relation
🔸Four accepted theories to explain the centric relation (CR):
(i) Muscle theory
(ii) Ligament theory
(iii) Osteofibre theory
(iv) Meniscus theory
💠 Materials used for temporary record bases:
🔸 Shellac
🔸 Cold-cure acrylic
🔸 Vacuum-formed vinyl or polystyrene
🔸 Baseplate wax
💠 Materials used for permanent record bases:
🔸 Heat-cure acrylic
🔸 Gold
🔸 CoCr alloy
🔸 NiCr alloy
🔍 METHODS OF RECORDING HORIZONTAL JAW RELATION
👉 Classification of methods for recording CR:
💠 According to C.O. Bouchers
(i) Static Methods: In this, the mandible is caused to assume CR position and the rims are locked into this position. Advantage is that it causes minimal displacement of the recording bases in relation to the supporting base.
(ii) Functional Methods: Records are made when the mandible is in function. The disadvantage of this method is causing lateral displacement and anteroposterior displacement of the recording bases.
🔺 Direct recording
🔺 Graphic recording
🔺 Functional recording
🔺 Cephalometric method
Patient-guided methods of recording CR
🔺 Schuyler technique
🔺 Physiological technique
🔺 Gothic arch (arrow point tracing)
🔺 Myo-monitor technique
Operator-guided methods
🔺 Chin point guidance methods
🔺 Three finger chin point guidance methods
🔺 Bimanual manipulation method
🔺 Anterior guidance with Lucia jig
🔺 Anterior guidance by a leaf gauge
🔺 Anterior guidance by OSU Woelfel gauge
🔺 Power centric registration method
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