TRIPASS XR تري باس

 • Whip-Mix: According to their design of their ear bow, in

anteroposterior direction at anterior wall of external auditory

meatus and in superior–inferior direction approximately at level of

most prominent point of posterior border of tragus.

• Brandrup-Wognsen: About 12 mm anterior to the most prominent

point of posterior border of tragus on line from it to the outer

canthus of the eye.

• Weinberg’s Point: A point 11–13 mm anterior on a reference line

drawn from the middle and posterior border of tragus of the ear to

the corner of the eye.

• Gysi: About 13 mm anterior to anterior margin of external auditory

meatus on line from superior margin of external auditory meatus

and the outer canthus of the eye.

FIGURE 5-9 Beyron’s point (P).

Hinge axis

Definition

Hinge axis or transverse horizontal axis is defined as ‘an imaginary line

around which the mandible may rotate within the sagittal axis’. (GPT 8th

Ed)

Hinge axis is also called horizontal axis, intercondylar axis, terminal

hinge axis, transverse horizontal axis.

Concepts of hinge axis

Transverse horizontal axis (THA)

Authors who advocated that THA exists are B.B. McCollum, C.E.

Stuart, R.B. Sloane, H. Sicher and Allil.

• The THA is the most retruded hinge position and is significant

because it is learnable, repeatable and recordable and coincides with

CR. The limits of the hinge movement in this position are about 12–

15° at condyles or 19–21 mm in the incisal region.

• The THA plus one other anterior point serves to locate the maxillae in

space and to record the static starting point for functional

mandibular movements.

• The recording and reproduction of the opening axis of the mandible

enables a given occlusal relation to be reproduced on the articulator at any

vertical height without the necessity of making a new interocclusal

(IO)–centric relation (CR) record at new VDO.

Gnathology

The proponents (McCollum, Stuart, Sloane, Allil) of gnathology claim

that there is one THA common to both condyles.

• The condyles are in a definite position in the fossa during the

rotation.

• Snow recognized the importance of this axis and to transfer this axis

to the articulator led to the development of facebow. In 1921,

McCollum, Stuart and others reported the first method of

transferring this axis.

Transographics

The proponents (Page, Trapozzanno, Lazzari) of transographics claim

that each condyle has a different THA.

H. Page (1957):

• He was the first one to state the theory of split

hinge axis. He also stated that:

• There were at least 12 hinge axes in every head.

• Three in each TMJ

• Three in each mandibular angle

• These, he said, were responsible for movements in

all three planes.

V.R. Tropazzono and J.B. Lazzari (1957):

• They found the presence of multiple hinge axes.

• Relaxation of the patient, during the making of THA

recordings is essential.

Because of the presence of multiple hinge axes points, increase or

decrease of the VD on the articulator is contraindicated unless a new

interocclusal record is made on the patient at the desired VDO.

L.A. Weinberg (1958):

• He refuted the transographic concept.

• He said that because it was mechanically impossible

for a solid object to have two axial centres of

rotation in the same plane for one direction of

movement.

Schools of thought regarding the transverse axis

• Absolute location of the axis: The absolute location of the hinge axis school,

as practised by V. Lucia (1953), B.B. McCollum (1939, 1943), E.R.

Granger (1952, 1954).

• Arbitrary location of the axis: The arbitrary axis school as practised by

Craddock and Symmons (1952).

• Nonbelievers in the transverse axis location: Nonbelievers such as H.A.

Collett (1955), R. Levao (1955), L.E. Kurlh and I.K. Feitistein (1951),

F.W. Craddock and H.F. Symmons (1952) and H.O. Beck (1959)

expressed doubts about the presence of THA.

• They thought that the axis is theoretically possible

but not practically acceptable.

• Split axis rotation: Page, V.R. Trapozzanno, J.B. Lazzari, F.R. Slavens

(1961) believed in the transographic theory.

• They believe in the split axis with which each

condyle rotates independently of the other, as the

mandible is not bilaterally symmetrical.

• There must be two axes parallel to each other with

both axes at right angles to the opening and closing

movement of the mandible.

Articulators

Definition

Articulator is defined as ‘a mechanical instrument that represents the

temporomandibular joints and jaws, to which maxillary and mandibular

casts may be attached to simulate some or all mandibular movements’. (GPT

8th Ed)

Uses

• To diagnose the state of occlusion in both the natural and artificial

dentitions.

• To plan dental procedures based on the relationship between

opposing natural and artificial teeth.

• To aid in the fabrication of restorations and prosthodontics

replacements.

• To correct and modify completed restorations.

• To arrange artificial teeth.

Requirements of an Articulator

Minimal requirements

• It should hold cast in correct horizontal and vertical relationship.

• The cast should be easily removable and re-attachable.

• It should provide a positive anterior vertical stop (incisal pin).

• It should accept facebow transfer record using an anterior reference

point.

• It should open and close in a hinge movement.

• It should be made of noncorrosive and rigid materials that resist

wear and tear.

• It should not be bulky or heavy.

• There should be adequate space present between the upper and

lower members.

• The moving parts should move freely without any friction.

• The nonmoving parts should be of rigid construction.

Additional requirements are as follows:

• The condylar guides should allow protrusive and lateral jaw

motions.

• The condylar guides should be adjustable to accept and alter the

Bennett movement.

• The incisal guide table should be customizable.

• It should have adjustable intercondylar distance.

Advantages of articulators

• These allow the operator to visualize the patient’s occlusion,

especially from the lingual aspect.

• Patient’s cooperation is not a factor when using an articulator once

the appropriate interocclusal records are obtained from the patient.

• The refinement of complete denture occlusion in the mouth is

difficult. This is eliminated by the use of articulators.

tors.

• These reduce the chairside time.

• The patient’s saliva, tongue and cheeks do not interfere when using

articulators.

Limitations

• An articulator can simulate but not duplicate jaw movements.

• Articulators made of metal may show error due to tooling or error

resulting from metal fatigue and wear.

• The articulator may not exactly simulate the intraborder and

functional movements of the mandible.

• Thus, the mouth would be the best place to complete the occlusion,

but using the jaws as an articulator also has limitations:

• Inability of humans to visually detect the finer

changes in the motion

• Making accurate marks in the presence of saliva

• Exact location of the condyles

• The resiliency of the supporting structures

• The dentures are movable on slippery base

Evolution of articulators

Articulators have evolved from simple hinge axis device to more

sophisticated instruments simulating the movements of the jaws

accurately. The objective of evolution was to reproduce the occlusal

relationships extraorally.

1756: Plaster articulator was first described by Phillip Pfaff. It is also

called slab articulator.

1805: First mechanical articulator described by JB Gariot.

1800s: Barn door hinge articulators.

1800s: Adaptable barn door hinge was capable of opening and closing

only in a hinge movement. It has anterior vertical stop between the

upper and lower members. It is also known as Dayton Dunbar

Campbell instrument.

1840: J. Cameron and T.W. Evans made attempt to device plane line

articulator.

1858: W.G.A. Bonwill developed an articulator based on the theory of

equilateral triangle (Bonwill triangle). It was the first of the kind of

articulator that imitated the movements of mandible in eccentric

movements.

1896: P.M. Walker devised a clinometer which had provision for Gothic

arch tracings.

1902: M.M. Kerr articulator developed by Kerr brothers had fixed

protrusive and lateral movements. Hinge was located at

approximately the same place as the occlusal plane of the mounted

cast.

1906: New century articulator developed by George B. Snow.

1910: Acme articulator was also developed by George B Snow. It had

three models of different widths with three ranges of intercondylar

width.

1910: Gysi’s adaptable articulator developed by Gysi.

1914: Gysi simplex articulator was introduced. Condylar guidance of

this articulator was fixed at 33° and was shaped like ‘ogee path’.

This path is an S-shaped curve in profile.

1918: Maxillomandibular instrument developed by George Monson.

This articulator was based on the spherical theory of occlusion.

1923: Rudolph L. Hanau developed Hanau model M Kinescope

articulator. This articulator has two condylar posts on each side.

Bennett angle was adjusted here.

1923: Homer Relator was introduced by Joseph Homer. Plastic

material was used to preserve the articulator positions.

1927: Hanau model H110 modified introduced incisal guide table.

1929: Stansberry tripod instrument was developed without hinge to

reproduce any functional relationship.

1938: Phillips occlusoscope did not use facebow. The articulator was

adjusted by either intraoral or extraoral records.

1950s: Coble articulator maintained CR and vertical dimension (VD)

but did not allow functional movements.

1955: Pankey–Mann articulator was developed by L.D. Pankey and

A.W. Mann.

1956: Stuart articulator was developed by Charles E. Stuart. It is a fully

adjustable arcon-type articulator.

1963: Hanau model H2 Series. It had increased distance between the

upper and lower members from 95 to 110 mm.

1958: Dentatus ARL articulator. It is a semi-adjustable articulator with

straight condylar path and fixed intercondylar distance.

1960: Verticulator developed by William Windish.

1962: Ney articulator is an arcon-type articulator with no locking

device between the upper and lower members in CR.

1964: Whip-Mix articulator was developed by Charles E. Stuart. It is a

semi-adjustable articulator which has three intercondylar

adjustments (Fig. 5-10).

1968: Denar D4A articulator developed by Niles Guichet. It is a fully

adjustable articulator which is programmed by tracings made with

pneumatically controlled pantographs.

1971: Simulator evolved from Granger Gnathoscope. It is a fully

adjustable articulator that is set from pantographic tracings,

positional records and other tracings.

1975: Denar Mark II by S. Hobo and F.V. Celanza.

1978: Penadent articulator – based on the work of Robert Lee.

1981: Panahoby articulator – Arcon-type semi-adjustable articulator

devised by S. Hobo. It had provisions of adjustment of sagittal

inclination of condylar path between 0° and 60°, immediate

mandibular lateral translation between 0 and 4 mm, progressive

lateral translation between 0° and 25°.

1982: Cyberhoby articulator – Fully adjustable articulator devised by

S. Hobo.

FIGURE 5-10 Whip-Mix articulator.

The articulators have evolved over the period of time and the

present generation of articulators such as KaVo Protar, Denar Mark II,

Panadent, Hanau radial shift incorporate the Bennett movement in

order to simulate the mandibular movements as closely as possible.

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

Based on instrument functions

According to the International Prosthodontic Workshop on Complete

Denture Occlusion at University of Michigan in 1972, articulators are

classified as follows:

Class I

• Simple holding instruments capable of accepting a

single static registration.

• The first articulators were known as ‘slab

articulators’. Plaster indices extended from the

posterior portion of the casts and were keyed to

each other by means of these indices (e.g. JB

Gariot’s hinge articulator [1805]).

Class II

Instruments that permit horizontal as well as vertical

motion but do not orient the motion to TMJ with

facebow transfer.

Class IIA

• It permits eccentric motion based on average or

arbitrary values.

• In this type, the condyles are on the lower member

and their paths are inclined at 15°. Casts are

mounted to this articulator according to Bonwill’s

theory (e.g. Gritmann articulator [1899]).

Gysi simplex articulator (1914) has the condylar path

inclined at 30° and the incisal fixed at 60°.

Class IIB

• Permits eccentric motion based on arbitrary theories

of motion (e.g. maxillomandibular instrument

designed by Monson in 1918 based on his spherical

theory of occlusion).

Class IIC

• Permits eccentric motion based on engraved records

obtained from the patient and does not accept a

facebow transfer (e.g. House articulator designed

by MM House in 1927).

Class III

• Instruments that simulate condylar pathways by

average or mechanical equivalents for all or part of

the motion and allow for joint orientation of the

casts with a facebow transfer.

Class IIIA

• Accepts facebow transfer and a protrusive

interocclusal record (e.g. Hanau model H designed

by Rudolph Hanau in 1923, Dentatus articulator

[1944]).

Class IIIB

• Accepts facebow transfer, protrusive interocclusal

records and some lateral interocclusal records.

• For example, A. Gysi (1926) introduced the Trubyte

articulator. It is a nonarcon instrument with a fixed

intercondylar distance. The horizontal condylar

inclinations are individually adjustable and the

individual Bennett adjustments are located near the

centre of the intercondylar axis. The incisal guide

table is adjustable.

Class IV

• Instrument accepts three-dimensional dynamic

registrations and utilizes a facebow transfer.

Class IVA

• The condylar pathways are formed by registrations

engraved by the patient (e.g. TMJ instruments

designed by Kenneth Swanson in 1965).

Class IVB

• Condylar pathways are selectively angled and

customized.

For example, gnathoscope designed by Charles Stuart

in 1955, Niles Guichet in 1968 designed the Denar

(D4A) fully adjustable articulator. The latest

instrument in Denar series is D5A which has the

plastic condylar inserts. This has provision for both

immediate and progressive side shift Bennett

adjustment.

Based on the ability to simulate jaw movements

Class I

• These are instruments that receive and reproduce

stereograms (pantograms). These articulators can

be adjusted to permit individual condylar

movement in each of the three planes. These are

capable of reproducing the timing of the side shift

of the orbiting (balancing) side and its direction on

the rotating (working) side.

Class II

• Instruments that will not receive stereograms. Some

of the instruments have fixed controls whereas

others are adjustable, but usually in no more than

two planes. Most are set to anatomical averages or

with some type of positional records.

• This class is divided into four types:

Type 1 (hinge): This type is capable of opening and

closing in a hinge movement. A few permit limited

nonadjustable excursive-like movements.

Type 2 (arbitrary): This is designed to adapt to specific

theories of occlusion or is oriented to a specific

technique.

Type 3 (average): This type is designed to provide

condylar element guidance by means of averages,

positional records or mini-recorder systems. Most

permit adjustments of both horizontal and lateral

guidance surfaces. Some types of facebow can be

used in maxillary cast orientation.

Type 4 (special): This type is designed and used

primarily for complete dentures.

Class II (Type 2)

• Monson

• Handy II

• The correlator

• Transograph

• The gnathic relator

• Verticulator

Class II (Type 3)

• House

• Dentatus

• Hanau (several models)

• Whip-Mix (several models)

• Denar: Mark II and Omni model

• TMJ: Mechanical fossa and moulded fossa models

• Panadent

Based on the adjustability of the articulator

• Nonadjustable

• Semi-adjustable

• Fully adjustable

Based on the types of records used for their

adjustment

Interocclusal record adjustment

• Most articulators used for fabrication of complete dentures are

adjusted by some kind of interocclusal records.

• These records are made in wax, plaster of Paris, zinc oxide eugenol

paste or cold curing acrylic resin.

Graphic record adjustment

• Articulators designed for the use with graphic records are generally

more complicated than those designed for interocclusal records.

• As graphic records consist of records of extreme border positions of

the mandibular movements, the articulator must be capable of

producing at least the equivalent of curved movements.

Based on the theories of occlusion

Bonwill theory articulators

• One of the early instruments that reproduced eccentric movement

was the Bonwill articulator.

• Although Bonwill invented his articulator in 1858, it was marketed

only in late 1880s.

• According to the Bonwill’s theory of occlusion, the teeth move in

relation to each other as guided by the condylar and the incisal

guidances.

• Bonwill’s theory is also known as the theory of equilateral triangle

according to which the distance between the condyles is equal to

the distance between the condyles and the midpoint of the

mandibular incisors (incisal point).

• An equilateral triangle is formed between the two condyles and the

incisal point. Theoretically, the dimension of the equilateral triangle

is 4 inches.

• Bonwill articulators allow lateral movement and permit the

movement of the mechanism (joint) only in the horizontal plane

(Fig. 5-11).

FIGURE 5-11 Diagrammatic representation of Bonwill

triangle.

Conical theory articulators (proposed by R. E. Hall).

The conical theory of occlusion proposed that the lower teeth move

over the surfaces of the upper teeth as over the surface of a cone,

generating an angle of 45° with the central axis of the cone tipped 45°

to the occlusal plane (Fig. 5-12).

FIGURE 5-12 Diagrammatic representation of the conical

theory of occlusion.

Spherical theory articulators

• The articulator devised by G.S. Monson in 1918 operated on the

spherical theory of occlusion.

• The spherical theory of occlusion proposed that lower teeth move

over the surface of upper teeth as over a surface of sphere with a

diameter of 8 inches.

• The centre of sphere was located in the region of glabella.

Semi-adjustable articulators.

These have adjustable horizontal condylar paths, adjustable lateral

condylar paths, adjustable incisal guide tables and adjustable

intercondylar distances. The degree and ease of these adjustments

differ.

There are two types of semi-adjustable articulators:

(i) Arcon articulators

(ii) Nonarcon articulators

Features

• These articulators are used to simulate the patient’s condylar path

by using mechanical equivalents which has capacity to simulate all

or part of its motion.

• Casts mounted in this articulator have approximately the same

spatial relationship as the condyle to the teeth, thus discrepancies in

the difference in the radius of arc of closure is minimized.

• Therefore, the occlusal discrepancies in the finished restoration are

minimal.

• Facebow transfer is necessary to use semi-adjustable articulators.

• It is useful in diagnostic evaluation of the study cast, occlusal

analysis, occlusion correction and rehabilitation.

• It is ideal to use a semi-adjustable articulator with facebow for

complete denture fabrication with minimal occlusal errors.

• It is the more preferred articulator for complete denture construction to

fully adjustable as it is comparatively easy to use and requires less

time and is cheaper.

• It is the articulator of choice for denture remount procedures.

• Semi-adjustable articulator can accept centric, lateral and protrusive

records.

• It can be arcon or nonarcon depending on the location of the

condylar guides and condylar elements.

Arcon and nonarcon articulators.

The term arcon was given by G. Bergstorm. ‘Ar’ means articulator and

‘con’ means condyle. The differences between arcon and nonarcon

articulators are given in Table 5-2.

TABLE 5-2

DIFFERENCES BETWEEN ARCON AND NONARCON

ARTICULATORS

Arcon Articulator Nonarcon Articulator

The condylar element is attached to the lower member

of the articulator and the condylar guidance is attached

to the upper member

Condylar guidance is attached to the lower

member and the condylar elements are attached

to the upper member

Simulates TMJ Does not simulate TMJ

The facebow transfer, occlusal plane and the

relationship of the opposing casts are preserved when

the articulator is opened and closed

Angulation between the condylar inclination and

the occlusal plane changes when the articulator is

opened and closed

Upper member is rigid and the lower member is

movable as in the patient

Upper member is movable and lower member is

rigid

Examples are Hanau Wide Vu and Whip-Mix Examples are Hanau H series, Dentatus and Gysi

Fully adjustable articulators

• A fully adjustable articulator is an instrument that will accept threedimensional ‘dynamic’ registrations.

• These are capable of being adjusted to follow the mandibular

movement in all directions.

• By virtue of numerous adjustments available on it, the articulator is

capable of repeating most of the precise condylar movements

depicted in any individual patient. The adjustments include the

following:

• Adjustable horizontal condylar guidance

• Adjustable lateral condylar guidance

• Adjustable incisal guide table

Adjustable intercondylar distance, i.e. the fully adjustable

articulator can accept the following records:

• Centric

• Protrusive

• Lateral

• Facebow transfer

• Intercondylar distance

Stuart instrument gnathoscope is an example of fully adjustable

articulators.

Advantages

• Most accurate instrument to reproduce restorations that precisely fit

the occlusal requirements of the patient.

Disadvantages

• Expensive

• Demands high degree of skill

• Time consuming

Indications

• Primarily for extensive treatment requiring the reconstruction of an

entire occlusion.

Split cast method and its importance

Definition

Split cast method is defined as ‘method of mounting casts wherein the

dental cast’s base is sharply grooved and keyed to the mounting ring’s base.

The procedure allows verifying the accuracy of the mounting, ease of removal

and replacement of the casts’. (GPT 8th Ed)

• This technique was first introduced by A.G. Lauritzen.

Uses

• It is an useful method of relating upper and lower cast to each other

in the articulator for the purpose of occlusal rehabilitation.

• It is used to compare the interocclusal records.

• It is used in mounting casts for multiple restorations or full mouth

rehabilitation.

Benefits

• To verify plaster records in centric and to adjust the horizontal

condylar inclination in the articulator.

• To verify centric records during full mouth rehabilitation.

• To check the accuracy of hinge axis transfer.

• To observe processing errors during clinical remount procedure.

• To simplify waxing and carving procedure, as the master cast can be

easily removed from the articulator and replaced back.

Split cast methods

• Custom cut notches (Lauritzen)

• Custom-made grooves

• Split cast formers – diagonal grooves

• Magnetic split cast

Technique employed

Preparation of the primary cast

• Impression is poured with stone conventionally.

• Sides and base of the cast is trimmed to form a primary cast.

Preparation of the secondary cast

• V-shaped notches are made on the base of the cast with cylindrical

stone.

• Two notches are made in the area of lateral incisor, two at the buccal

border and one at the posterior border of the cast.

• Box the cast after applying separating medium around the cast.

• Stone is poured in the boxed cast with different colour to form the

secondary cast.

Separation of the split cast

• Secondary cast is separated from the primary cast and its fit into the

grooves is verified.

• The separated secondary cast is assembled back on the primary cast.

• Split cast consists of a primary cast with five notches and a

secondary cast with five ridges corresponding to the notches.

Articulation of the split cast

• Split cast is mounted on the articulator with the help of facebow

transfer.

• Split cast technique allows separation of the primary cast from the

secondary cast which is mounted on the upper member of the

articulator.

Mounting lower cast to articulator with centric

record

Centric interocclusal record is used to mount the lower cast with the

upper cast.

Verification of several interocclusal centric

records with split cast

• After mounting, the interocclusal record is removed and the second

record is placed in its position over the lower cast.

• Upper split cast is removed from the mounting and positioned over

the interocclusal record.

• The upper member of the articulator which has the secondary cast is

lowered into the base of the upper primary cast until the notches

engage its counterpart.

• If the notches engage accurately, the interocclusal centric record is

correct.

• If the notches do not engage accurately, another interocclusal record

is made.

• At least two interocclusal centric records should fit the cast

accurately in order to verify the record.

• This shows consistency and accuracy of the interocclusal centric

record.

• Only then it is accepted as the true centric record.

Bennett movement

Definition

Bennett movement or laterotrusion is defined as ‘condylar movement on

the working side in the horizontal plane. This term may be used in

combination with terms describing condylar movement in other planes, for

example, laterodetrusion, lateroprotrusion, lateroretrusion and

laterosurtrusion’. (GPT 8th Ed)

Or

‘the direct lateral side shift of the mandible that occurs simultaneously with a

lateral mandibular excursion’. (Bouchers)

The term Bennett movement is obsolete and is referred to as

lateroretrusion.