ПРЕПАРИРОВАНИЕ ЗУБОВ по герберту

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ПРЕПАРИРОВАНИЕ!ЗУБОВ!по!герберту5шиллинбургу,!

http://www.dentaljuce.com/fruit/page.asp?pid=106!

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ASSESSMENT.

Study the unprepared tooth; visualize the preparation shape you want to achieve.

Decide which areas will be restored with alloy and which areas will require more room for alloy an only.

Plan where you will place your finishing lines, and what type of margin will be where.

OCCUSAL DEPTH SLOTS (GROOVES) – BUCCAL CUSP

Using 501 round-ended tapered diamond* cut a depth slot into the central ridge of the buccal cus cusp will be covered in alloy and porcelain, reduction should be 2.0mm. Cut 2 more occlusal slots and distally to the first.

*The 501 bur acts as your depth gauge, its dimensions are: Tip 1.1mm; Maximum diameter 1.6m 7.0mm ; Taper 4.5° (9° convergence)

OCCLUSAL DEPTH SLOTS – PALATAL CUSP

Cut 3 slots in the palatal cusp, at depth 1.5mm if it is to be covered in alloy only or 2.0mm if porc coverage is required.

JOIN DEPTH SLOTS – BUCCAL CUSP.

Using 501 join depth slots on the buccal cusp to create a smooth, uniform, planar reduction that general occlusal morphology.

Note that a thin band of marginal ridge can be left unprepared to prevent bur contact with the ad and aid in depth orientation.

JOIN DEPTH SLOTS – PALATAL CUSP. Repeat for palatal cusp.

FUNCTIONAL CUSP BEVEL.

Use 501 to prepare a smooth, uniform functional cusp bevel on the palatal cusp, at an angle that approximates the inclination of the opposing cusps (about 45°).

Reduction is 1.5mm for alloy; 2.0mm for gold, and can be begun with depth grooves.

BUCCAL DEPTH SLOTS – OCCLUSAL HALF.

Buccal axial reduction is completed in 2 (or more) planes because of the curvature usually presen premolars.

Use 501 bur to cut 1.5mm depth slots in the occlusal half of the buccal surface, fading out at the bulbosity.

BUCCAL DEPTH SLOTS – CERVICAL HALF.

Using 501 bur cut 1.0mm deep marginal depth slots parallel to the cervical half of the buccal surf depth slots supragingivally.

BUCCAL DEPTH SLOTS – CERVICAL HALF. Alternative view

PLANAR BUCCAL REDUCTION.

Attempting the buccal axial reduction in one plane will:

-Cut too much tooth away in the middle of the buccal surface.

-Create an irretrievable over-taper of the buccal surface.

-Risk pulpal exposure.

-Leave occlusal 1/3 of axial wall under-prepared, resulting in a finished crown of poor contour.