Model operation

5.1 Dental laboratory

5.1.1 Creation of dental casts and production of relaxation splint


Fig 5-1 Necessary working materials (modeling clay, mechanical pencil, set square, caliper, ruler, dental probe, protractor, red and black permanent marker, dental laboratory).

Fig 5-2 Jet Blue (Coltene) bite registratrion.

Figs 5-3a and 5-3b Creation of two maxillary and two mandibular casts (one pair of casts for the model operation, one pair of casts for reference. The second maxillary cast is required for manufacture of the first osteotomy splint.

Fig 5-4 TMJ-adjusted articulation of the maxillary cast using the facebow with bite fork and transfer aid.

Fig 5-5 Articulation of the mandibular cast using a trimmed registration (unblocked). The registration is trimmed laterally to allow checking of whether the casts placed on top of each other have gaps when articulating.

Figs 5-6a to 5-6d Initial position of maxilla and mandible in the model (from front, left, right, and back).

Production of the relaxation splint

The maxilla and mandible are in the rest position.

Figs 5-7a to 5-7d Production of the relaxation splint in the initial position (approximately 3-mm blocking).

Figs 5-8a and 5-8b Relaxation splint (initial position) with hooks in the canine and molar region on both sides for attaching elastics for trial wear on the maxilla.

Fig 5-9 The relaxation splint must be sufficiently strong (therefore 3-mm blocking) so that the hooks do not break off too easily, but should be as thin as possible.

5.2 Clinic

The relaxation splint is checked on the patient. Operation planning then takes place.

5.3 Dental laboratory

The model operation is based on the following system: First, the target occlusion is set, if necessary also with multiple division of the maxilla/mandible. Only then is the skeletal position (position of the maxillomandibular complex in the facial skull) determined.

5.3.1 Determination of the target occlusion and model analysis

Figs 5-10a to 5-10f A close-up view from behind reveals an arch disrepancy between the maxilla and mandible. The excessively narrow maxilla must be widened transversely during the model surgery.

Figs 5-11a to 5-11d The casts are positioned in Angle Class I and at a suitable width with finding of the interference contacts [at teeth 37 (a and b) and 47 (c and d)]. In this case, a satisfactory target occlusion can be achived with a maxillary bisection.

Figs 5-12a and 5-12b Abrading of the interference contacts and marking (bracket on 37 and 47) of the abraded facets for the clinical splint try-in.

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Jan 19, 2024 | Posted by in Orthodontics | Comments Off on Model operation

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