Restorative - Outcome 6 Flashcards
The preparation of a cavity results in..
The preparation of cavities results in the formation of various lines, walls, and angles.
Cavity Wall is…
A wall is an enclosing side of a prepared cavity. The cavity wall is named for the surface of the tooth toward which it is placed
A pulpal floor/wall is..
is the portion of the cavity prep that is external to the pulp (or covers the pulp)
An axial wall is…
that area of the prepared cavity that is parallel to the long axis of the tooth
A line angle is formed…
where two walls meet
A point angle is where…
three walls meet and form a point
A cavo-surface angle or margin is…
is a line angle in a prepared cavity formed at the junction of te wall of the cavity and the surface of the tooth
4 Steps in Cavity Preparation
The principals of cavity preparation presented to the dental profession by. Dr. Black are still being used in cavity design
The dentist will design a preparation based on the location and extend of the caries and the type of restorative material to be used
- Obtain the Required Outline Form
- Obtain the Required Resistance and Retention Form
- Obtain the Required Retention Form
- Convenience Form
Step 1 of Cavity Preparation - Obtain the Required Outline Form
-the outline form is the overall shape of the preparation along the external surface of the enamel or the Cavo-surface margin.
- it is determined by the size and shape of the carious lesion and by the need for a suitable design that will hold a restoration firmly in place
-concept has changed since Dr. Black’s original steps in 1859. (he believed sulcus was bacteria free so all preparations should be made in sulcus to avoid recurrent caries)
-today, there is an extension of the preparation to eliminated deep occlusal fissures and to place the margins or the restoration in areas that are easy to clean
Following principles form the basis for what appear to be scientifically acceptable cavity outlines for restorative dentistry:
-Cavity preparations should be related to the anatomy of the tooth, its position in relation to other teeth, the extent of the carious lesion, and the physical properties of the replacement material.
-Cavity preparations should not be cut to specific stereotyped forms.
-Whenever possible, gingival margins of cavity preparations should end on enamel rather than on dentin or cementum.
-Whenever possible, cavity preparation margins are extended supragingival.
-Margins of posterior cavity preparations should not end directly in contact points.
Step 2 of Cavity Preparation - Obtain the Required Resistance and Retention Form
Resistance form is the internal shape of the cavity preparation.
The shape is designed to protect both the restoration and the tooth from fracture when biting forces are applied to the restored tooth.
Step 3 of Cavity Preparation - Obtain the Required Retention Form
Retention form is the relationship that exists between different walls of the cavity preparation.
An amalga preparation generally has walls that are either parallel or slightly undercut which creates mechanical retention of the restorative material. Retention is also enhanced by the addition of retentive grooves in the walls of the preparation.
Step 4 of Cavity Preparation - Convenience Form
The Dental Assistant’s Role - Instruments and materials in Cavity Preparation
Prepare the operatory setup for the restorative procedure
Maintain moisture control using suction and placement of the dental dam
Transfer dental instruments
Properly mix and transfer or place dental materials
Perform any required steps such as placing bases or liners and/or matrices and wedges
Maintain patient comfort throughout the procedure
Maintain appropriate infection control precautions
Single working end instruments are..
Single working end instruments are designed for a very specific area or task.
Double ended/paired intruments have…
Double-ended instruments, or paired instruments, have one end for one surface of the tooth or side of the mouth and the other end for the opposite side of the tooth or mouth.
Straight instrument
If the instrument has a shank with no angles it is termed ‘straight’ and will be used in the anterior part of the mouth.
The instrument will be held in a palm-thumb grasp
Curved instruments
If the instrument has a shank with a curve it is usually one that is designed by a specific dentist and will usually have the name of the dentist assigned to it.
The instrument willl be held in a palm-thumb grasp.
Instrument Shank Angles
If the shank has one angle it is described as ‘monangled.’
If the shank has two angles it is called ‘binangled’ and will be held in a pen grasp.
If the shank has three angles it is called ‘triple angled’ and will be held in a pen grasp.
If the shank has four angles it is called ‘quadrangled’ and will be held in a pen grasp.
Instrument Bevels
Instruments are designed to work on the right or left, mesial or distal surface of the tooth or on the right or left side of the mouth with the placement of a bevel or angle on the cutting edge.
The bevel of an instrument has been cut or sharpened to form one angle or two. If an instrument is dropped and broken, the bevel will probably be gone and the instrument will not cut. The terminology used to describe bevels is “single beveled” meaning one cut, or “bi- bevelled” which means it comes to a point like a knife.
Rotary Burs
Rotary burs are instruments that are required in all areas of dentistry. In restorative dentistry they are used to cut through the tooth structure in order to gain tooth access, remove decay, and create mechanical retention.
Rotary instruments are unique in the fact that they are not utilized with manual strength. These instruments require the use of a dental handpiece to rotate the cutting edges at either high or low speeds in order to cut tooth structure, bone, or restorative materials.
Grips
Low-speed handpieces operate on low RPM, and the rotary burs constructed for this handpiece
have a latch style locking mechanism to anchor the bur in the head.
Highspeed handpieces operate at a higher RPM and a friction grip style bur is utilized as a locking mechanism to anchor the bur in the head.
Safety Notes:
To prevent injury to the dental healthcare worker and /or patient, all rotary instruments must be locked into place and checked for secure placement prior to operating.
High-speed rotary burs should not cut into a vital tooth without the use of water spray. As the bur turns at a high RPM, there is a high risk of overheating and traumatizing the pulp.
Rotary Burs - Sizes and Shapes
Rotary burs are manufactured in multiple sizes and shapes based on the intended use. The dental assistant is required to identify the shapes and sizes to prepare for the procedure and order supplies.
Cavity Preparation Materials
Some common materials in this procedure include disposables such as gauze 2X2 or cotton pellets as well as a material used to detect decay by transferring colour onto demineralized carious dentin rendering it more visible to the operator for removal. This material is in a liquid format and is often called a “caries detector.”
