TOPIC: ARTICULATORS AND FACEBOWS
🎯 KEY FACTS
🔹Arcon Articulators contain the condylar guidance within the upper member and the condylar elements within the lower member.
🔹Functional Articulation is the occlusal contact of the maxillary and mandibular teeth during mastication and deglutition.
🔹Bennett Angle is formed between the sagittal plane and the orbital path (horizontal lateral condylar path). Average Bennett angle is between 7.5º and 12.8º.
🔹Bonwill Triangle is a 4-inch equilateral triangle bounded by lines connecting the contact points of the incisal edges of mandibular central incisors to each condyle and from one condyle to the other.
🔹Frankfort Horizontal Plane (Fh Plane) is a horizontal plane which is established by joining the line between the lowest point on the margin of the orbit to the highest point on the margin of the auditory meatus.
🔹Bonwill Triangle was first given by W.G.A. Bonwill in 1858.
🔹Fischer’s Angle is the angle formed between the sagittal protrusive condylar path and the sagittal lateral condylar path. Its average the value is 5º.
🔹Pantographic Tracing is the graphic record of the jaw movements recorded in all the three planes, i.e. horizontal, sagittal and frontal with the help of styli on the recording tables of the pantograph or by means of electronic sensors.
🔹The articulation of natural dentures in the patient mouth is called Anatomical Articulation.
🔹Dummy Dentures used for preliminary work in denture construction are called occlusal rims.
🔹Pure Hinge movement occurs at the terminal hinge position.
🔹Bennett Shift of the mandible is the direct lateral shift of the condyle during lateral movements.
🔹Kinematic Facebow is attached to the lower rim.
🔹Balkwill’s Angle is the angle formed between the occlusal plane and the Bonwill’s triangle.
🔹Average progressive Bennett shift is 7.5º.
🔹Average immediate Bennett shift is between 0 and 2.5 mm.
🔹The intercondylar distance in Whip-Mix Articulator can vary between 88 and 112 mm.
🔹RUM Position (rearmost, uppermost, midmost condylar position) of the condyles was proposed by C.E. Stuart (1969). It was considered a physiologic condylar position, harmonious with the centric occlusion.
📣 DIFFERENCES BETWEEN IMMEDIATE SIDE SHIFT AND PROGRESSIVE SIDE SHIFT
📌 Types Of Mandibular Movements
💠 On The Basis Of TMJ Movement
(i) Rotational movement can occur around three reference planes:
🔸 Rotation around the horizontal axis
🔸 Rotation around the vertical axis
🔸 Rotation around the sagittal axis
(ii) Translational movement
💠 On The Basis Of Types Of Movement
i) Hinge movement
ii) Retrusive movement
iii) Protrusive movement
(iv) Lateral excursive movement
(v) Medial excursive movement
💠 On The Basis Of Extent Of The Movement
(i) Border movement
🔸 Border movements around the horizontal plane
🔸 Border movements around the sagittal plane
🔸 Border movements around the frontal plane
(ii) Intraborder movement
🔸 Functional movements
🔸 Chewing
🔸 Speech
🔸 Swallowing
🔸 Parafunctional movements
🔸 Bruxism
🔸 Clenching
🔸 Any habitual movement
📌 Classification Of Articulators
🔸 Based on instrument functions
🔸 Based on the ability to simulate jaw movements
🔸 Based on the adjustability of the articulator
🔸 Based on the theories of occlusion
🔸 Based on the type of interocclusal record used
📌 Types Of Facebow
📣 Facebows are usually of the following two types:
(i) Arbitrary facebow
🔸 Earpiece type
🔸 Fascia type
(ii) Kinematic facebow
📌 Split Cast Methods
🔸 Custom cut notches (Lauritzen)
🔸 Custom-made grooves
🔸 Split cast formers – diagonal grooves
🔸 Magnetic split cast