صناعة

• Mounting the casts on articulator

• (Lab Procedure)

صناعة / د . هند (م 10 – 11)

اسنان ثاني موصل
7 / 12 / 2015
د . هند (م 11)

Mounting :

It is the procedure of attaching the maxillary and mandibular casts to the articulator in their recorded jaw relation. It is also called articulation.
The maxillary cast is first articulated, and then the mandibular cast is articulated after recording the vertical and centric jaw relations.

Preparation of the Cast For Mounting

1. Determine the midline of the cast according to the midline of incisive papilla and continue this line posteriorly all around the cast.
2. The casts should be placed in slurry water for better adhesion of the casts to the mounting plaster.
3. With wax knife, 3-4 V-shape cuts on the base of upper and lower casts, so as to facilitate the laboratory remounting.
4. Coat the base of the casts with Vaseline or any separating medium.

Mounting the maxillary cast

The maxillary cast is first mounted to the upper member of the articulator after orientation jaw relation by using the face-bow with adjustable type of articulators, while for the mean value articulator use the mounting table to support the maxillary occlusion rim in its position during mounting. The mandibular cast is articulated after recording the vertical and centric jaw relations

Mean value articulator

Mounting the maxillary cast
After recording the orientation jaw relation, the following steps are carried out:
1. Enough space should be present between the base of the cast and the upper member of the articulator to accommodate for the plaster material over the cast. If there is not enough space trimming should be done to the base of the cast;

2. Alignment of the midline maxillary cast occlusion rim to the midline of articulator.

3. Plaster is mixed according to the manufacturer instruction then the plaster is poured over the base of the cast and the upper member is closed until the incisal pin touches the incisal table.

4. Smoothing and polishing of the mounting plaster is done.

Figure : Face-bow transfer supports the maxillary occlusion rim in its position during mounting in semi-adjustable articulator













Figure : Mounting table supports the maxillary occlusion rim in its position during mounting in mean value articulator

Mounting mandibular cast

The mandibular cast is mounted after recording the vertical and centric jaw relations.
1. The articulator with the mounted maxillary cast is inverted to aid in the mounting the mandibular cast.
2. Care should be taken that there is no posterior interference between the maxillary and mandibular casts (Heel area).
3. Centric records(The maxillary occlusal rim with mandibular occlusal rim) placed on the mounted maxillary cast.
4. The mandibular cast is placed on the mandibular occlusal rim (It should be soaked in slurry water before mounting).











Heel area

centric record

Figure : Mounting the mandibular cast in semiadjustable articulator.

5. The plaster is mixed and poured over the base of the mandibular cast and the articulator is closed until the incisal table touch the incisal pin, then the plaster should be smoothed and polished.

Figure : Mounting the mandibular cast in mean value articulator.

Possible errors during mounting
1. The record base is not properly secured to the cast.
2. Interference of the casts posteriorly.
3. The incisal pin does not touch the incisal table.
4. The incisal pin is not properly screwed.
5. Wrong transference of the midline of the articulator with that of the casts (shifting of the midline).
6. Movement of the casts during mounting.
7. Maxillary and mandibular rims are not properly fixed after making centric record.
8. Dimensional changes in the plaster material