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Articulators

Dr Matsubara

LEARNING OUTCOMES:

1. Explain the importance of the articulator for oral rehabilitation
2. Describe the classification of articulators
3. Understand the difference between ARCON and NON-ARCON articulators
4. Describe the Facebow recording and its clinical importance
5. Describe bite registration in CR and when to mount in CR or MIP
6. Describe the programming of a semi-adjustable articulator

THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia

LEARNING OUTCOMES:

1) Explain the importance of the articulator for oral rehabilitation 2) Describe the classification of articulators 3) Understand the difference between ARCON and NON-ARCON articulators 4) Describe the Facebow recording and its clinical importance 5) Describe bite registration in CR and when to mount in CR or MIP 6) Describe the programming of a semi-adjustable articulator

                                                  

Terminology and Definitions³⁴

• Bennet angle: Adjustability in the angle formed between the sagittal plane and the condylar track in the nonworking side.
• Bennett movement: lateral shift of the mandible resulting from the movements of the condyles along the lateral inclines of the mandibular fossae during lateral jaw movement
• Intercondylar distance: Refers to the distance between the vertical axes of rotation
• Horizontal axis of rotation: Mandibular movement around the horizontal axis is an opening and closing motion.
• Incisal guidance: The simulation of anterior guidance in the natural dentition.
• Condylar & glenoid fossa components: Variability in the angle of the eminentia; the directional condylar guidance provided by the medial, superior and posterior walls of the glenoid fossa; and the ability to simulate laterotrusive and protusive movements.

A mechanical instrument that represents the TMJs and jaws, to which maxillary and mandibular casts may be attached to simulate some or all mandibular movements

Glossary of Prosthodontic Terms 9th ed.

Articulators

”A mechanical instrument that represents the TMJs and jaws, to which maxillary and mandibular casts may be attached to simulate some or all mandibular movements”

Glossary of Prosthodontic Terms 9th ed.

   

Functions and Clinical Indications⁵⁶⁷⁸⁹

FUNCTION

• To evaluate the patient’s occlusion (simulate mandibular movements and hold casts in a determined fixed relationship)
• To allow most of the prosthetic work to be done without the presence of the patient
• Dental laboratory can then design the prosthesis (occlusal surfaces) to be in functional harmony with the patient’s movements
• To reduce clinical time needed for adjustments of restorations

ASSIST IN: Diagnosis & treatment planning, and fabrication of restorations

LIMITATIONS

• Due to their inflexible mechanical nature, articulators cannot simulate the complex tissues, joints; and neuromuscular control that influence mandibular movements.
• Even the most advanced and expensive articulator, can only be customised to simulate, but still not fully replicate, all possible combinations of movements in the patient

Human masticatory system is the ultimate articulator

When should you mount the models on articulators?

• To assess occlusion (Diagnostic Articulation)
• Diagnostic wax up
• More than two single crowns / Bridge
• Removable partial dentures
• Complete dentures
• Immediate dentures (partial or complete)
• Cases where increase of VD is necessary (wax up)
• Occlusal splints (if not using CAD-CAM)
• Single crowns ??

During treatment planning: Diagnostic Articulation

• Tooth alignment
• Prosthetic/interocclusal space
• Occlusal contacts
• Occlusal plane
• Enough space for restorations,
• Shape, morphology and size of artificial teeth (Partial dentures and immediate dentures)
• Occlusal rest (guide planes, adequate height of contour, undercuts – surveyor)

Do you need to mount study models on articulator for Complete Denture treatment plan?

No, we can change all those parameters in a complete denture.

Note: Edentulous patient with severe class II or III, you may need to mount the models to assess ridge relationship.

Case Study Exception

In cases of severe Class II or Class III malocclusion, study models should be mounted to assess the ridge relationship and determine if pre-prosthetic surgery is required.

     

Classification of Articulators^{10111213141516171819202122232425}

Based on:

• Instrument function
• Adjustability

CLASSIFICATION BASED ON INSTRUMENT FUNCTION

Capacity to simulate mandibular movements

• Class I: Hinge type
• Class II: Arbitrary
• Class III: Average
• Class IV: Special

Class I: Hinge type

• Simplest instrument
• Accept a single static registration
• Only vertical motion is passible
• Cannot accept a facebow
• Limited use: very simple restorations

Class II: Arbitrary

Articulator that allow horizontal and vertical movements but it does not orient the motion of TMJs

Class III: Average

• Simulates condylar pathways by using averages or mechanical equivalents for all or part of the motion
• Allows vertical and horizontal motion
• Use of face-bow transfer
• Does not allow total customization of condylar pathways

Class IV: Special

• Accept three dimentions dynamic registrations
• Use of facebow transfer
• Capable of accurately reproduce the condylar pathway
• Able to adjust multiple angles

CLASSIFICATION BASED ON ADJUSTABILITY

• Nonadjustable articulator
• Semi-adjustable articulator
• Fully-adjustable articulator

Nonadjustable articulator:

• Class I articulator
• Open and close in a fixed horizontal axis

Indication: simple cases (e.g. single crown)

Semi-adjustable articulator:

• Class III articulator
• Condylar guidance incline, Bennet angle, incisal guidance, inter condylar distance
• Two types:
  • Arcon articulator
  • Non-arcon articulator

ARCON Type

Ar – articulator Con – condyle

This type resemble the TMJ:

• Condylar element (sphere) is attached to the lower member of the articulator
• Mechanical fossae is attached to the upper member

Simulated the correct anatomical position of the TMJ elements

Example: Kavo Protar, Whip Mix

NONARCON Type

• Condylar element (sphere) is attached to the upper member of the articulator
• Mechanical fossae is attached to the lower member

Upper and lower components are rigidly attached – easier to handle

Example: Hanau, Dentatus articulator

ARCON vs NONARCON

ARCON Articulator	NONARCON Articulator
- Condylar inclination is at a fixed angle to the maxillary occlusal plane	- the angle changes as the articulator is opened ↓ Errors to program the articulator (protrusive record)

Horizontal axis of rotation

A) Semi-adjustable articulator B) Nonadjustable Articulator Type I

Premature contact, interference

Fully adjustable articulator:

• Class IV articulator
• Capable of being adjusted to follow the mandibular movement in all direction
• Condylar guidance, Bennet angle, Fisher angle, intercondylar distance, anterior guide
• Not commonly used due to its complexity

The articulator is an essential tool in successful denture manufacturing that allows for the correct positioning of artificial teeth, which in turn result in balanced articulation and a successful prosthodontic appliance

Programming the Articulator

Once models are mounted, the semi-adjustable articulator must be programmed using four specific bite registrations:

• ==Centric Relation: To mount the lower model.==
• ==Protrusion: To set the Condylar Guidance. The glenoid fossa component is adjusted until it touches the condylar sphere in the protruded position.==
• ==Lateral Left: To set the Right Bennett Angle (non-working side).==
• ==Lateral Right: To set the Left Bennett Angle (non-working side).==

Clinical Tip

If the mounting does not look exactly like the patient's mouth, do not send it to the lab. Errors at this stage lead to significant occlusal interferences and may require the entire process to be restarted..

Articulators

CLASSIFICATION BASED ON INSTRUMENT FUNCTION

• Capacity to simulate mandibular movements

Class I: Hinge type Class II: Arbitrary Class III: Average Class IV: Special

Articulators

CLASSIFICATION BASED ON INSTRUMENT FUNCTION

Class I: Hinge type

• Simplest instrument
• Accept a single static registration
• Only vertical motion is passible
• Cannot accept a facebow
• Limited use: very simple restorations

Articulators

CLASSIFICATION BASED ON INSTRUMENT FUNCTION

Class II: Arbitrary

• Articulator that allow horizontal and vertical movements but it does not orient the motion of TMJs

Articulators

THE UNIVERSITY OF WESTERN AUSTRALIA Oral Health Centre of Western Australia

CLASSIFICATION BASED ON INSTRUMENT FUNCTION

Class III: Average

• Simulates condylar pathways by using averages or mechanical equivalents for all or part of the motion
• Allows vertical and horizontal motion
• Use of face-bow transfer
• Does not allow total customization of condylar pathways

Articulators

CLASSIFICATION BASED ON INSTRUMENT FUNCTION

Class IV: Special

• Accept three dimentions dynamic registrations
• Use of facebow transfer
• Capable of accurately reproduce the condylar pathway
• Able to adjust multiple angles

Articulators

CLASSIFICATION BASED ON ADJUSTABILITY

• Nonadjustable articulator
• Semi-adjustable articulator
• Fully-adjustable articulator

Articulators

CLASSIFICATION BASED ON ADJUSTABILITY

Nonadjustable articulator:

• Class I articulator
• Open and close in a fixed horizontal axis

Indication: simple cases (e.g. single crown)

Articulators

CLASSIFICATION BASED ON ADJUSTABILITY

Semi-adjustable articulator:

• Class III articulator
• Condylar guidance incline, Bennet angle, incisal guidance, inter condylar distance*
• Two types:
  • Arcon articulator
  • Non-arcon articulator

Articulators

CLASSIFICATION BASED ON ADJUSTABILITY Semi-adjustable articulator

ARCON Type

Ar – articulator Con – condyle

This type resemble the TMJ:

• Condylar element (sphere) is attached to the lower member of the articulator
• Mechanical fossae is attached to the upper member

Simulated the correct anatomical position of the TMJ elements

The angle between the condylar guidance and the maxillary occlusal plane remains constant regardless of the articulator's opening.

Example: Kavo Protar, Whip Mix

Articulators

CLASSIFICATION BASED ON ADJUSTABILITY Semi-adjustable articulator NONARCON Type

• Condylar element (sphere) is attached to the upper member of the articulator
• Mechanical fossae is attached to the lower member

Upper and lower components are rigidly attached – easier to handle

The angle of condylar guidance changes as the articulator opens, which can introduce errors during excursive movement simulation.

Example: Hanau, Dentatus articulator

Articulators

CLASSIFICATION BASED ON ADJUSTABILITY Semi-adjustable articulator

ARCON vs NONARCON

ARCON Articulator	NONARCON Articulator
Condylar inclination is at a fixed angle to the maxillary occlusal plane	the angle changes as the articulator is opened $\downarrow$ Errors to program the articulator (protrusive record)

Contemporary Fixed Prosthodontics 4^th^

Articulators

SEMI-ADJUSTABLE

ARCON NONARCON

Articulators

THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia

CLASSIFICATION BASED ON ADJUSTABILITY

Horizontal axis of rotation

A) Semi-adjustable articulator

B) Nonadjustable Articulator Type I

Premature contact, interference

Contemporary Fixed Prosthodontics 4

Articulators

CLASSIFICATION BASED ON ADJUSTABILITY

Fully adjustable articulator:

• Class IV articulator
• Capable of being adjusted to follow the mandibular movement in all direction
• Condylar guidance, Bennet angle, Fisher angle, intercondylar distance, anterior guide
• Not commonly used due to its complexity

• The articulator is an essential tool in successful denture manufacturing that allows for the correct positioning of artificial teeth, which in turn result in balanced articulation and a successful prosthodontic appliance.

                                         

Facebow Recording^{262728293031323334353637383940414243444546474849505152}

Aim: to record the anteroposterior and mediolateral spatial position of the maxillary occlusal plane in relation to horizontal axis of rotation of the mandible during opening and closing, and to the cranial base

Clinical Importance

• It ensures the maxillary model is mounted at the correct distance from the hinge axis.
• ==Error Prevention: Mounting without a facebow (e.g., too close to the hinge) results in a more vertical arc of closure than the patient’s actual movement. This leads to “high” restorations and premature contacts in the mouth that were not visible on the articulator.== .

Kavo Protar facebow

Model mounted with facebow

OVD Reduction

Model mounted without facebow

OVD Reduction

Reduce more than necessary

• Frankfurt Horizontal plane
  • 1- Infra-orbital point
  • 6 - Porion
• Camper’s plane (2)
  • 3 – Subnasal point
  • 5 - Tragus
• 7 – Hinge axis
• 4 Occlusal plane

2 // 4

Kavo Protar facebow

Can use either Frankfurt or Camper’s plane

1. Nasal support

INTERCONDILAR ADJUSTMENT (Not available on Kavo PROTAR)

Intercondylar Distance

3 2 1

Large Medium Small

FACEBOW RECORD

1. Impression of maxillary cusp tips on the fork.

   • Automixed elastomer
   • Addition or condensation silicone putty
   • Impression Compound (not available in the clinic)

2. Place the prepared bite fork in the patient’s mouth: patient can hold it against the upper teeth.

   • The post is usually offset to the left, not the midline.
   • For partial or complete edentulous cases, you need a base and wax rim to provide posterior support.

3. Adapt the bow to the width of the patient’s face.

4. Adjust the nasal support on the nasion and fix it with the lock lever.

   NOTE: If the Frankfurter horizontal is used, the reference pointer must be inserted above the bow. If the Camper plane is used, the reference pointer must be positioned below the bow.

5. Shove the bite fork support onto the bite fork ④.

6. Adapt the bite fork support on the facial bow and tighten the the finger screw ①. Make sure that the guide pins of the bite fork support engage in the guide groove of the facial bow.

7. Tighten the knurled screw ②.

Articulators

Facebow

Aim: to record the anteroposterior and mediolateral spatial position of the maxillary occlusal plane in relation to horizontal axis of rotation of the mandible during opening and closing, and to the cranial base.

Kavo Protar facebow

Model mounted with facebow

OVD Reduction

Model mounted without facebow

Model mounted without facebow

Model mounted without facebow

OVD Reduction

Reduce more than necessary

Articulators

1- Infra-orbital point 6 - Porion } Frankfurt Horizontal plane

3 – Subnasal point 5 - Tragus } 2 Camper’s plane

7 – Hinge axis 4 Occlusal plane

2 // 4

Articulators

Kavo Protar facebow

Can use either Frankfurt or Camper’s plane

1. Nasal support

Articulators

INTERCONDILAR ADJUSTMENT (Not available on Kavo PROTAR)

Articulators

INTERCONDILAR ADJUSTMENT (Not available on Kavo PROTAR)

3 2 1

Large Medium Small

Articulators

Intercondylar Distance

Articulators

FACEBOW RECORD

1^st Impression of maxillary cusp tips on the fork

Automixed elastomer	Addition or condensation silicone putty

Impression Compound (not available in the clinic)

Articulators

FACEBOW RECORD

2^nd Place the prepared bite fork in the patient’s mouth: patient can hold it against the upper teeth

Partial or complete edentulous cases

Need base and wax rim to provide posterior support

Articulators

FACEBOW RECORD

3^nd Adapt the bow to the width of the patient’s face.

4^th Adjust the nasal support on the nasion and fix it with the lock lever

NOTE: If the Frankfurter horizontal is used, the reference pointer must be inserted above the bow. If the Camper plane is used, the reference pointer must be positioned below the bow.

Articulators FACEBOW RECORD

5^th Shove the bite fork support onto the bite fork ④

6^th Adapt the bite fork support on the facial bow and tighten the the finger screw ① Make sure that the guide pins of the bite fork support engage in the guide groove of the facial bow.

7^th Tighten the knurled screw ②

                                                                 

Bite Registration and Centric Relation^{535455565758596061626364656667}

Should I use CR or MIP (habitual bite position)?

Confirmative approach: patient has stable bite, no symptoms of TMD

• Prosthetic treatment in MIP, habitual bite position.

Reorganized approach: patient with no stable bite, loss of VD, signs and symptoms of TMD

• Prosthetic treatment in CR

A second option for Reorganized approach: Freedom in centric: Reestablish the bite in CR and leave area of freedom in the restoration so that the patient can function anywhere between CR and old habitual position (MIP) if necessary.

MIP (habitual bite position)

• Respect working time of bite registration material
• Do not use a lot of material
• Check if the patient is contacting upper and lower teeth

MOUNTING OF MANDIBULAR MODEL

BITE REGISTRATION IN CR

RC = Most posterior position of the mandible in which the condyle is in the most anterior and superior position within the fossa.

Manipulating a patient’s mandible:

• Tongue tip to soft palate

• ==Bimanual Manipulation: Manual guidance of the mandible.==

• ==Leaf Gauge: Using layers of plastic to separate posterior teeth, allowing the condyle to seat superior-anteriorly.==

”Lucia Jig” / Anterior jig

• Small anterior programming device made of acrylic resin.
• It should create a platform and keep the teeth about 1 mm apart.
• Prevent posterior contact points.
• Help mandible manipulation.
• Used for an RC record.

Other methods:

• Occlusal splint
• Kois deprogrammer

Jaw Relation Record

Requirements:

• Durability
• Rigidity
• Ease of application
• Ease of transfer

For edentulous areas:

• stabilizing base and occlusal rim
• Consider multiple records to ensure repeatability

Suitable materials:

• Wax
• Silicone
• ZnO-eugenol
• Resin

Articulators

MIP (habitual bite position)

• Respect working time of bite registration material
• Do not use a lot of material
• Check if the patient is contacting upper and lower teeth

Articulators

MOUNTING OF MANDIBULAR MODEL

BITE REGISTRATION IN CR

RC = Most posterior position of the mandible in which the condyle is in the most anterior and superior position within the fossa.

Manipulating a patient’s mandible

Contemporary Fixed Prosthodontics 4ᵗʰ

Articulators

BITE REGISTRATION IN CR

Tongue tip to soft palate

Articulators

BITE REGISTRATION IN CR

Articulators

BITE REGISTRATION IN CR ”Lucia Jig”

• Small anterior programming device made of acrylic resin
• Prevent posterior contact points
• Help mandible manipulation

Articulators

BITE REGISTRATION IN CR ”Lucia Jig”

Articulators

BITE REGISTRATION IN CR

”Lucia Jig”

1 mm apart

Articulators

BITE REGISTRATION IN CR ”Lucia Jig”

Create a platform

Articulators

BITE REGISTRATION IN CR ”Lucia Jig”

Articulators

BITE REGISTRATION IN CR ”Lucia Jig”

RC record

Articulators

BITE REGISTRATION IN CR

”Lucia Jig”

Articulators

BITE REGISTRATION IN CR

Occlusal splint

Kois deprogrammer

Articulators

THE UNIVERSITY OF WESTERN AUSTRALIA | Oral Health Centre of Western Australia

BITE REGISTRATION IN CR

Anterior jig

Kois deprogrammer

Articulators

Jaw Relation Record

• Requirements:

  • Durability
  • Rigidity
  • Ease of application
  • Ease of transfer

• For edentulous areas: stabilizing base and occlusal rim Consider multiple records to ensure repeatability

Suitable materials Wax Silicone ZnO-eugenol Resin

                                                           

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