Types of ArticulatorsTypes of ArticulatorsLecture notesLecture notes

AbdulsalamAbdulsalam A. A. ZwiadZwiadBDS,HD., BDS,HD., M.ScM.Sc. FIHTS, . FIHTS, Ce.ImplCe.Impl..

AssociAssoci. Prof.. Prof. Faculty of Medical Sciences Faculty of Medical Sciences Queen Queen ArwaArwa University University

Former Assist. Prof. Baghdad UniversityFormer Assist. Prof. Baghdad University

DefinitionDefinition

►► It is a mechanical device represents the TMJ, It is a mechanical device represents the TMJ, maxillary and maxillary and mandibularmandibular arches.arches.

►► It can be used to hold the upper and lower casts It can be used to hold the upper and lower casts according to their relationships to facilitate the according to their relationships to facilitate the purposes of diagnosis and arrangement of artificial purposes of diagnosis and arrangement of artificial teeth out side the patient mouth. teeth out side the patient mouth.

►► It is an instrument that acts as the patients in their It is an instrument that acts as the patients in their absence and provide media of working without the absence and provide media of working without the interference of cheek , lips , saliva and tongue.interference of cheek , lips , saliva and tongue.

Articulation requirementsArticulation requirements

►► It must accurately maintain centric relation or occlusion. It must accurately maintain centric relation or occlusion. ►► Casts must be easily attached and removed. Casts must be easily attached and removed. ►► The pin must be adjusted in contact with the The pin must be adjusted in contact with the incisalincisal

table. table. ►► It must open and close on a hinge. It must open and close on a hinge. ►► There must be adequate distance between the upper and There must be adequate distance between the upper and

lower arms. lower arms. ►► It must be stable on the workIt must be stable on the work--bench. bench. ►► It must not be too heavy.It must not be too heavy.

Classification of ArticulatorsClassification of Articulators

Arc of occlusion and dimensional measurements of the jaws Arc of occlusion and dimensional measurements of the jaws relations could be transfer to the articulator according to relations could be transfer to the articulator according to its simplest or adjustable articulation depending to the its simplest or adjustable articulation depending to the

types of articulators.types of articulators.

In this lecture we try to give a simplest In this lecture we try to give a simplest presentation about the various methods of presentation about the various methods of classification articulators.classification articulators.

Type I Simple hinge articulatorsType I Simple hinge articulators

Consists of two united arms which have ability of opening and Consists of two united arms which have ability of opening and closing in a closing in a hinge movements based on Bonhinge movements based on Bon--Will triangle concept which proposed that Will triangle concept which proposed that there is 10 cm. (4inch) distance between both there is 10 cm. (4inch) distance between both condylescondyles and 10 cm. and 10 cm. distance between each distance between each condylecondyle and the and the incisalincisal point, that the upper and point, that the upper and lower teeth move in relation to each other as guided by the lower teeth move in relation to each other as guided by the condylarscondylarscontrol and control and insisalinsisal point.point.

IncisalIncisal pointpoint

10 cm 10 cm

10 cm

TMJTMJ

A view of simple hinge articulatorA view of simple hinge articulator

Type II Mean Value ArticulatorType II Mean Value Articulator

This type proposed that the articulator provide lateral and This type proposed that the articulator provide lateral and protrusive movement and based on average protrusive movement and based on average condylercondyler guidance guidance ( 30( 3000 ) and incisive guidance (10) and incisive guidance (1000 ) e.g.: ) e.g.: gysigysi articulator .articulator .

A view of Mean value ArticulatorA view of Mean value Articulator

3 Adjustable Articulator 3 Adjustable Articulator They are :They are :

A) semiA) semi--adjustable adjustable B) Fully adjustable articulatorsB) Fully adjustable articulators

adjustable Articulatoradjustable Articulator--A ) SemiA ) Semi

This type depends on face bow transfer and protrusive This type depends on face bow transfer and protrusive condylarcondylar path obtain from the patient mouth while the path obtain from the patient mouth while the lateral lateral condylarcondylar path is adjusted according to an average path is adjusted according to an average value by special formula: value by special formula:

L = H / 8 +12 L = H / 8 +12 ((hanu`shanu`s formula)formula)

HH = protrusive = protrusive LL = lateral= lateral

A view of an adjustable articulator with a face bow A view of an adjustable articulator with a face bow

transferredtransferred

B ) Fully adjustable articulatorB ) Fully adjustable articulator

The horizontal and later The horizontal and later condylarcondylar path inclination path inclination can be obtain from the patient mouth beside the can be obtain from the patient mouth beside the using of faceusing of face--bow.bow.

Face bowFace bow►► Face bow consist of UFace bow consist of U--shape frame shape frame

which is large enough to external which is large enough to external from the TMJ.from the TMJ.

►► In have the In have the condylarcondylar rods attached rods attached to the to the condoylarcondoylar region and there region and there is the fork which touch and hold is the fork which touch and hold the upper occlusion rim . the upper occlusion rim .

►► The The condoylarcondoylar rods position in front rods position in front of external auditory of external auditory meatusmeatus 13mm. 13mm. on the line extend from outer on the line extend from outer canthuscanthus to the top of the to the top of the tragustragus. .

►► The face bow have the functions of The face bow have the functions of locating the hinge axis and related locating the hinge axis and related the maxillary cast to this axis and the maxillary cast to this axis and then to facilitate the mount of the then to facilitate the mount of the upper cast.upper cast.

B ) Kinematics' Face bowB ) Kinematics' Face bow

It has the ability to locate the exact position for the center oIt has the ability to locate the exact position for the center of f rotation by using special marker and by closing and opening rotation by using special marker and by closing and opening the mouth this marker can record many points that it is the mouth this marker can record many points that it is finally will record or mark only one point provide the pure finally will record or mark only one point provide the pure rotation on it with out translation to an other point .So this rotation on it with out translation to an other point .So this point will be called the center of rotation which determine point will be called the center of rotation which determine the terminal hinge axis exactly.the terminal hinge axis exactly.

classifingclassifingAnother method of Another method of ArticulatorsArticulators

ClCl. I . I --Only vertical movement (hinge) Only vertical movement (hinge)

ClCl. II . II -- Vertical and horizontal movement Vertical and horizontal movement --no no facebowfacebowmounting.mounting.

ClCl. III . III -- Uses average equivalents for setting the articulator Uses average equivalents for setting the articulator elements and accepts elements and accepts facebowfacebow registration.registration.

ClCl. IV . IV -- Accepts three dimensional dynamic registrations and Accepts three dimensional dynamic registrations and

requires a facerequires a face--bow mounting.bow mounting.

ArconArcon articulatorarticulator

1.1. It is another type of articulator with the It is another type of articulator with the equivalent equivalent condylarcondylar guides fixed to the upper guides fixed to the upper member and the hinge axis to the lower member and the hinge axis to the lower member;member;

22. . An instrument that maintains a constant An instrument that maintains a constant relationship between the relationship between the occlusalocclusal plane and the plane and the arconarcon guides at any position of the upper guides at any position of the upper memermemer..

Importance of Hinge AxisImportance of Hinge Axis

A healthy T.M.J. provides a "hinge axis" motion of A healthy T.M.J. provides a "hinge axis" motion of the mandible with an ideal the mandible with an ideal mandibularmandibular arc of arc of closure to the centric occlusion or relation.closure to the centric occlusion or relation.