Caries Classification and Class I Preps Flashcards
Caries occurring in pits and fissures on the occlusal surfaces of posterior teeth, buccal and lingual surfaces of molars, lingual surfaces of maxillary anterior teeth (general)
Pit and fissure carries
Caries occurring on the surfaces that are “pit and fissure free”
Smooth surface caries
Caries occurring more in elderly, follows advanced gingival recession
Root surface caries
Incipient, Small, Moderate, and Extensive classify _______.
Stage of caries
Where do recurrent/secondary caries occur?
Under a preexisting restoration.
G.V. Black
Create of one type of cavity classification system; said the location of the lesion dictated the design of the cavity preparation.
Caries classification:
Pits and fissures of: occlusal surfaces of premolars and molars; buccal or lingual pits/fissure of the molars; lingual pit near the cingulum of the maxillary incisors.
Class I
Caries classification:
Involving the proximal surfaces (mesial and distal) of premolars and molars
Class II
Caries classification:
Proximal (mesial and distal) surfaces of incisors and canines.
Class III
Caries classification:
Proximal surfaces of incisors and canines, but also will involve the incisal
edge
Class IV
Caries classification: gingival third (the area near the gingiva) of the facial or lingual surfaces of any tooth
Class V
Caries classification:
Involve the incisal edges of anterior teeth and the cusp tips of posterior teeth. Carious lesions are rare.
Class VI
Fundamental concepts for all tooth preparations:
1- Removal of dental caries
2- Removal of weak tooth structure to provide well supported sound hard tissue
3- Pulp protection
Healthy state is reestablishing…
- Tooth is not diseased anymore
- Normal function and form
- Esthetically pleasing where indicated (anterior zone of the oral cavity)
Isthmus in a class I
narrowest portion of a cavity preparation
Isthmus in a class II
a portion of the cavity connecting an occlusal portion and a proximal portion together
Dovetail design includes each _______ and the ______ around the marginal pits
marginal fossa, developmental grooves
Junction between the external walls of the cavity preparation and the uncut tooth surface.
Cavosurface margin
Basic 6 Principles of Cavity Preparation
- Outline form
- Resistance form
- Retention form
- Convenience form
- Finishing
- Debridement
The shape of the cavity preparation; perimeter of the tooth preparation in
width, length and depth
Outline form
Factors governing outline form
- Conservation of tooth structure
- Location and the extent of the carious lesion
- Position of pit and fissure dictate the outline
Conservative approach to outline form
remove minimal amount of tooth (while still removing entire carious area and any weak enamel, e.g. no unsupported enamel)
Design features of cavity preparation
allowing the remaining tooth structure & the restoration to withstand
forces that are principally directed towards the long axis of the tooth.
Resistance form
Primary resistance factors
1-Removal of undermined surface enamel
2-Flat pulpal floor and Cavity wall angulation
3- Cavity preparation depth
4- Well defined rounded Internal line angles
5- Type of restorative material
Why have a box shaped cavity instead of a cup shaped cavity?
Helps with resistance form – cup shaped cavity would allow micro-movement of restoration in a wedging effect on the supporting dentin bridge
Minimum amalgam thickness to withstand forces (help with resistance form)
1.5mm
Amalgam has a _____ edge strength
low (so amalgam margin is of importance)
Desired cavosurface margin (Butt-joint Margin) for amalgam
90 degrees
Design features of the cavity preparation that prevent dislodgement of the restoration by lifting or tipping forces
Retention form
How is retention form achieved?
Making opposing walls parallel or slightly convergent towards occlusal
Sufficient access to the cavity, to facilitate visibility and instrumentation of the cavity preparation and the insertion of the restorative material.
Convenience form
Minimal diameter of any spot in a cavity
1.0mm so that the small end of the smallest condenser can fit
Finishing the cavosurface margin (enamel margin) to prevent jagged or rough outline
finishing
purpose of finishing the margin
to achieve the best marginal seal
Final step before restoring; rinsing the cavity with air/water spray and high suction evacuation
Debridement
Two cavities should not be united unless the separating ridge is less than ______
0.5 mm
Teeth with ridges that should not be prepped through unless decay is present on ridges
Maxillary molars (with oblique ridge) and Mandibular 1st premolars (with transverse ridge)
Isthmus width should not exceed ___ intercuspal distance
1/3 (but preferably 1/4 max)
Enamel rod direction in central, middle, and peripheral 1/3s away from long axis of tooth
central 1/3 = rods lean towards axis
middle 1/3 = parallel to long axis
peripheral 1/3 = away from long axis
Correct depth of the cavity preparation
0.2-0.5mm into dentin (1.5-2.0mm on ivorine teeth)
Dimensions of 330 bur
0.8mm diameter and 1.5mm depth
___mm of tooth structure should be left between cavosurface margin and proximal contact area to conserve marginal ridge
1.6mm
Pulpal floor should be ______ to long axis of tooth
perpendicular
Adequate depth insures proper _______ form
Resistance (allows amalgam to withstand opposing forces)
Proper isthmus measurement of a Class I prep on the ivorine teeth
1.0-1.2mm
Axial depth of an extension
1.0-1.2mm
