Articulator : a mechanical device which represent the TMJ and jaw to which maxillary and mandibular casts attached to stimulate jaw movement.
It classified based into adjustability into :
1-Simple hinge articulator :
It consist of two arms joint together by a hinge
Is not an articulator , at best it is a cast holder because it has limited movement which is often used for a simple fixed prosthodontics as only opening and closing of jaws , no lateral movement , and smaller than patient jaws. It has limited value in dentistry but allow evaluation of tooth arrangement on study cast and discussion with patients. after cast mounted use intraocculsal record
2- average value articulator :
It has (eccentric movement ) limited lateral and protrusive movement and permit horizontal and vertical but not orient movement because straight condylar path that set at 30 degree and can not change , 15 degree for incisal guidance and 110 mm for intercondylar distance .
Using dimension from the average distance between the condylar guidance and incisal, the condylar shafts placed at 110 mm from each other , are engaged the condylar slots. The condylar slots at 30 incline.which helps to push the condylar rod into position.the incisal pin rests on the incisal table,to maintain the vertical height and separation between the upper and lower members.there is a smaller ,thinner pin placed horizontally known as the midincisal pin.
The relationship of the maxilla to the condyles is established by the occlusal surface of the upper occlusal rim with the incisal pin & with the notches on the condylar posts at the rear of the articulator in accordance to Bonwill triangle.
Bonwill triangle : is equilateral triangle formed between incisal pin and condylar, it allow lateral movement.
Used for construction of simple , indirect restoration and for partial and compelet denture.
These have adjustable horizontal and lateral condylar path , adjutable incisal guide and intercondylar distance ,the degree and ease of these adjustable differ , it used in most restorative and prosthodontic purpose “diagnostic assessment, and most fixed parial denture ” ,.Records For a Semi-adjustable Articulator :Face-bow record, Inter occlusal record ,Protrusive record
Most accurate to produce restoration but its expansive , time consuming and required high degree of skill
There are two types of semi-adjustable :
B) non arcon
Arcon articulators :
Condylar is attached to the lower member of articulator and condylar guidance attached to upper member
Upper member is rigid and lower is moveable , stimulate TMJ , occlusal plane and relations between casts are preserved when articulator is opened and closed.
Condylar guidance attached to lower member and condylar element attached to upper member
Upper member is movable and lower is rigid
Does not stimulate TMJ
Angulation between condylar and occlusal plane changes when articular opened and closed.
Fixed intercondylar distance at 110 mm
It has dynamic registration, allow to mandible to move in all directions , numerous of adjustment available on it , include :
1-adjustable incisal guide table
2-adjustale horizontal condylar guidance
3-adjustable lateral condylar guidance
They are all arcon with adjustable intercondylar distance , they all accept eccentric jaw relation records , use pantograph register. Used for full mouth rehabilitation , extensive occlusal pathology.