-II- ARTICULATORS
Dr. Monia M.N. KandilArticulator
The articulator: Is a mechanical instrument that represents the temporomandibular joints and jaw members, to which maxillary and mandibular casts may be attached to simulate some or all- mandibular movementsArticulators
The non-adjustable articulatorSemi-adjustable articulator
Fully adjustable articulator
Arcon
Non- Arcon
Mean Value
Hinge
Panto-graphic tracing
Sterio-graphic
Non Adjustable Articulators
Hinge articulator
Mean Value articulatorSemi Adjustable Articulators
Some of semi-adjustable articulators (for example, the Hanau H series, the Dentatus, and the Gysi) have the condyles attached to the upper member of the instrument (non-arcon), whereas others have the condyle attached to the lower member as occurs in nature (arcon)Arcon articulator
Non Arcon articulatorDifference between Arcon & Non arcon articulators
Fully Adjustable ArticulatorsFully adjustable articulator
Deficiencies and inherent inadequacies of articulatorsAs the mandible closes around hinge axis (mha), the cusp tip of each mandibular tooth moves along an arc.
The distance between the teeth and the axis of rotation on the small instrument is consider shorter than it is in the skull with a resultant less of accuracy.
If the location of the axis of rotation relative to the cusp tip differs markedly from the patient to the articulator, the radius of the arc of closure of the cusp tips may be different producing an error.
The large dissimilarity between the (aha) and (mha) will produce a large discrepancy between the arc of closure of the articulator and of the mandible.
What if patient doesn’t match articulator? Articulator
PatientArticulators
mhaaha
Patients
Therefore the distance from the condyle to the teeth is crucial
We obtain a measurement of this distance with a facebowaha
mha
Records needed for mounting on a Semi-adjustable Articulator:
I-Face Bow record or by Bonwill triangleII-Centric relation record III-Eccentric relation records
a-Protrusive Record b-Lateral Excursion Records ??
Semi-adjustable Articulator
Can be programmed to reproduce some mandibular movement capabilities; usually limited to straight line movementsRemember
Fully-adjustable Articulator
An articulator that allows replication of three dimensional movement of recorded mandibular motions:Fully-Adjustable Articulator
• It is the most accurate instrument.• It is designed to reproduce the entire character of the mandibular border movements, including: immediate and progressive lateral translation, and the curvature and direction of the condylar inclination.• Intercondylar distance is completely adjustable. The tracing of condyle path way is accomplished by helping of a pantographic tracer.
The techniques required for its use demand a high degree of skill & are time consuming to accomplish. This type of instrument is expensive. For these reasons, they are used primarily for extensive treatment, requiring the reconstruction of an entire occlusion. Unavoidable errors that occur in recording the angulation of the condyle paths on using such instruments make their value doubtful.
Limitations of Fully adjustable condylar path articulators
Articulators of the fully adjustable type include for example:
Stansbery tripod articulator. Hanau Kinoscope articulator. The Denar articulators. H.O. Beck and Coworkers have developed an experimental articulator that takes the factor of time into account by correlating the time of movement in each of the three planes of the skull. Fully Adjustable PROTAR (9) articulator.Stansbery tripod articulator
Hanau Kinoscope articulatorDenar II
Denar V
Fully adjustable H.O. Beck experimentalarticulator
Fully Adjustable PROTAR (9)This class of articulators accepts registration of all anatomic determinant of occlusal morphology, and accept a “hinge axis” kinematic transfer bow.The incisal guidance can closely simulate the paths of natural dentition.This class is fully utilized in extensive restorative procedures, as well as adjunct to diagnostic determinations of TMJ dysfunction.
Records needed for mounting on a Fully Adjustable Articulator
Centric Relation Record
Hinge axis location and Face bow record
Pantographic tracings
Stereographs
A- Hinge axis location and Face bow record
Face bow record has to be made in relation to the actual terminal hinge axis. This should first be located using a Kinematic face bow.B- Centric Relation Record:
Since the use of such an articulator would be limited to those cases that need full reconstruction and rehabilitation It can be done byBut it prefers more sophisticated methods, such as:- Electronic recording techniques- Intraoral gothic arc registration Classic centric recordsC- Pantographic tracings
Tracing the exact movements made by the mandible to register the exact direction and path and amount of those movements.A pantographic tracing is made by the use of the pantograph, to record lateral and protrusive excursions
The pantograph
Consists of two facebows, one affixed to the maxilla while the other to the mandible, with the use of clutches that are attached to the teeth.The tracings are made by styli attached to one member and small tables upon which the tracings are drawn attached to the other member, opposite the styli. There are posterior vertical and horizontal tables on both right and left sides. The patient is instructed to move his mandible through protrusive, right and left lateral excursion movements, while the styli scribe on their opposing tables the paths followed by the condyles in those movements.
When the pantograph is attached to the articulator, adjustments and alterations are made to the movements of the articulator follows the same paths that was scribed by the styli on their tables, that is following the paths of the condyles in their movements. Computerized systems have also been developed. A print out is obtained and used to program the articulator. The computerized systems closely resembles the manual pantograph and are much more economical as regards time, as the transfer stage is eliminated.
Pantographic recording
For fully adjustable articulatorPantograph Computerized systems
D- Stereographs:This is another method for programming the fully adjustable articulators. Clutches are made to fit the teeth, and the patient is instructed to perform lateral and protrusive excursions, during which, studs in one clutch cut into the opposing one.
For programming the articulator, the clutches are transferred to it, and it is moved to follow along the paths formed by the cut out areas. The condyles of the articulator are made to mold auto-polymerizing resin, previously placed in the articulator fossae. This enables the original jaw movements to be reproduced when the clutches are removed.