Rationale for Use of Semi-Adjustable Articulators

Rationale for Use of Semi-Adjustable Articulators

Question. List various uses and requirements of articulators and describe in detail, semi-adjustable articulators.
Answer:

Semi-adjustable articulators Use Of Articulator

1. Is to act as the patient in the absence of the patient.
2. It is used to simulate the patient’s temporomandibular joints, muscles of mastication, and the complex neuromuscular mechanism that programs mandibular movements.
3. Mounting of dental casts for diagnosis, treatment planning, and patient presentation.
4. Fabrication of occlusal surfaces for dental restorations.
5. Arrangement of artificial teeth for complete and removable partial dentures.

Read And Learn More: Complete Dentures Question and Answers

Semi-adjustable articulators  Requirements of an Articulator

1. To maintain the correct horizontal and vertical relationship of the patient’s casts.
2. The cast should be easily removed and attached to the articulator without losing their correct horizontal and vertical relationship.
3. It should have an incisal guide pin with a positive stop that is adjustable and calibrated.
4. The articulator should be able to open and close in a hinge-like fashion.
5. The articulator should accept a face-bow transfer utilizing an anterior reference point.
6. The articulator should be accurate, rigid, and of a noncorrosive material able to resist wear.
7. The adjustments should be freely movable and secure.
8. There should be adequate distance between the upper and lower members with good rear vision.
9. The articulator should not be too bulky and heavy.

Semi-adjustable articulators  Additional Articulator Requirements

If dentures are to be fabricated with balanced occlusion.

1. The condylar guides should allow right lateral, left lateral, and protrusive movements.
2. The condylar guides should be adjustable horizontally.
3. Provisions for adjustment of Bennett movement.
4. The incisal guide table should be a mechanical table that can be adjusted in the sagittal and frontal planes or a customized table.

• • Optional articulator capabilities are adjustable intercondylar distance and an immediate Bennett adjustment. The articulator may either be arcon or non-arcon.

Hanau Articulators

Hanau Articulators Hanau H2

• The Hanau H2 articulator is non-arcon type with the condylar guidance controls attached to the lower member of the articulator. “
• It has a fixed intercondylar distance of 110 mm and does accept a face-bow transfer. The lateral horizontal condylar inclinations are set by the protrusive interocclusal record.
• The amount of Bennett movement is calculated from the lateral horizontal condylar inclinations and the vertical condylar posts are rotated accordingly.
• The mechanical incisal guide table is adjustable both in sagittal and frontal planes.

Hanau Articulators Procedure

• The maxillary cast is mounted on the Hanau H2 articulator by means of a face-bow transfer. The facia face-bow or earpiece face-bow can be used.
• The hinge axis is located (the axis around which the mandible may rotate without translation). The facia face-bow has adjustable condylar rods that are placed lightly against the face over the center of rotation of the condyles.

• The earpiece face-bow is placed in the external auditory canals and while transferring to the articulator, the earpieces are seated on the auditory pins of the centric locks which relate to the patient’s horizontal axis.
• The anterior reference point of the facia and earpiece face-bows can either be the orbital or the incisal plane.
• The anterior reference point along with the two posterior reference points form the axis orbital plane, which has the same occlusal plane that is in the patient’s skull.
• The incisal plane is adjusted so that it is level with the upper notch on the incisal pin when making the face-bow transfer.
• If orbitale is the anterior reference point then the orbitale pointer in the face-bow assembly should touch the orbitale indicator on the upper member of the articulator when making the transfer.
• The Hanau Twirl-Bow relates the maxillary arch to the Frankfort horizontal plane and this can be transferred to the articulator without physically attaching the face-bow to the articulator.
• This facebow allows the operator to open and close the earpieces simultaneously and equidistantly.
• A horizontal orbital pointer is attached to the right temple arm. The relationship is recorded by a transfer rod, which is attached to the bite fork perpendicular to the Frankfort horizontal plane. A mounting guide is utilized to mount the transfer rod and attached the bite fork to the articulator.

Hanau Articulators Advantages

Hanau Articulators Ease of Manipulation

The maxillary cast can be mounted on the articulator without the face bow.

Hanau Articulators Records

• Horizontal condylar inclinations are determined by means of a protrusive interocclusal record. The patient should protrude approximately 6 mm. The horizontal condylar guidances are adjusted until the maxillary cast seats into the protrusive interocclusal record.
• The amount of Bennett movement is calculated from the horizontal condylar settings by Hanau’s equation,
• Bennett angle (L) = (H/8) + 12
• Where H is the horizontal condylar inclination determined by the protrusive interocclusal record. If the horizontal condylar inclination is 30°, then the Bennett angle would be approximately 16°. The vertical condylar posts are then rotated to the calculated Bennett angulation.

Hanau Articulators Incisal Guide Pin And Incisal Table

• The mechanical incisal guide table is adjustable in sagittal and frontal planes. There is a single sagittal adjustment and right and left frontal adjustments.
• These adjustments are made to compensate for the amount of horizontal and vertical overlap incorporated in the anterior teeth arrangement.
• The setting of the incisal guide table protects the anterior teeth from dislodgment when arranging the posterior teeth.
• The sagittal inclination is determined by bringing the central incisors into an end-to-end relationship and the frontal adjustments are determined by bringing the cuspids into an end-to-end relationship.
• The incisal guide pin is straight or angled.
• The angled incisal guide pin always maintains an exact center of the table position even with a change in the vertical dimension of 5 mm.
• In the case of the straight incisal pin, any change in vertical dimension will alter the position of the incisal guide pin in relation to the incisal guide table and a readjustment of the incisal guide table is needed.