Day 2 Lecture 1 Flashcards
Caries
A multifacorial infectious disease that attacks teeth by certain bacteria if the conditions are permissible causing destruction (demineralization/ dissolution) of the tooth - bacteria are part of microflora. When other factors line up, you get caries. Mutens and… other primary bacteria (60+). Substrate is carbohydrates - used as food, pH of mouth also has a role.
Demineralization
Dissolving of the tooth. Collagen fibers (small amount - tooth is mostly calcium phosphate*) small amount of organic matter is broken down, Calcium phosphate demineralizes.
Remineralization
Opposite of demineralization. If remineralization exceeds demineralization, you’re good and no operation is needed. Enough flourides in saliva to where flourohydroxyapatite can form.
Caries classification
Stages: Incipient (reversible), small (operative 1), moderate, extensive.
incipient
No operation, still in enamel, not yet to DEJ.
Small
Operative 1. Caries has gone along enamel, has gotten to DEJ
Moderate
Has gone into enamel, spread in dentin.
Extensive
Deep enough caries to the point that the dentin has grown down to stop the caries from reaching the pulp.
Pit and fissure carries
pits and fissures on the occlusal surfaces of posterior teeth, buccal and lingual surfaces of molars, lingual surfaces of maxillary anterior teeth. On buccal surface of mandibular molars, lingual surface of maxillary molars, on cingulum of central and lateral incisors.
Smooth surface caries
on the surfaces that are “pit and fissure free.” Mainly on proximal surfaces, buccal surfaces of premolars.
Root surface caries
more in elderly, follows an advanced gingival recession.
Caries classification
Rate - active and arrested
Active
Rampant (acute) decay and chronic decay.
Rampant
Rapidly invading, softer lesions. Very smooth and mushy, usually due to something. Nursing bottles caries, radiaiton caries, meth mouth.
Chronic
slow, long standing, dark in color and so there is a good chance of remineralization in early stages (reverse the demineralization process)
Arrested
Not showing any further progression.
• Smooth and polished like surface
Recurrent/Secondary caries
Caries under preexisting faulty restoration.
Black’s classification of caries
Class I-Class VI - each class has a different cavity prep.
Class I
Pits and fissures of occlusal surfaces of premolars/molars, buccal or lingual pits/fissures of the molars, lingual pit near the cingulum of the maxillary incisors.
Class II
Involving proximal surfaces (mesial and distal) of premolars and molars.
Class III
Proximal (mesial and distal) surfaces of incisors and canines.
Class IV
Proximal surfaces of incisors and canines, but also will involve the incisal edge. Chips,
Class V
Gingival third (area near the gingiva) of the facial or lingual surfaces of any tooth. **Gingival = cervical in operative.
Class VI
Involves the incisal edges of anterior teeth and the cusp tips of posterior teeth. These are rare.
Amalgam
Intricate, requires a specific size/shape of cavity preps.
Tooth prep steps
- removal of caries, 2. removal of weak tooth structure to provide well supported hard tissue, 3. protect the pulp.
Caries prep goal
Not showing any further progression.
• Smooth and polished like surface
Healthy state is reestablishing the following
Tooth is not diseased anymore, normal function, aesthetically pleasing for anteriors
Walls
External wall and internal wall. External extend to outer uncut tooth surface. Internal walls do not. Angle based on long axis. Axial and perpendicular walls.
Cavosurface margin
External margin that touches an uncut tooth surface. Junction between external wall of prep and uncut tooth surface.
Dovetail
Class 1 - isthmus connects two dovetails. Dovetail design includes each marginal fossa and the developmental grooves around the marginal pits. See images.
Isthmus
Narrowest portion of cavity prep in class I, portion of the cavity connecting an occlusal and proximal portion in class II.
Axial walls
Parallel to long axis of tooth. Internal wall
Pulpal walls
Perpendicular to long axis. Internal wall. Also called perpendicular.
Wall names
Termed based on adjacent surfaces.
Line angles
Whether external or internal, use other rules. It is consistent.
Principles of amalgam cavity prep
- outline, 2. resistance, 3. retention, 4. convenience, 5. finsihsing, 6. debridement
Outline form - step 1
conservation of tooth structure Final shape of tooth, shape of cavity prep, perimeter of the tooth prep in width, length and depth. Factors - conservation of tooth structure, location and extent of the carious lesion, position of pit and fissures. Extent of lesions - entire carious area should be removed, any weak enamel removed.
Old outline form vs new
Old - extensive tooth preps, unnecessary loss of structure. New - conservative approach to try to lessen amount of lost tooth structure. Composite is more conservative
Maxillary tooth anat
Oblique ridge. Separating ridge - less than 0.5mm of enamel will require joining cavities. Oblique ridge should not be touched otherwise, as it is important.
Resistance form - step 2
Design features of cavity prep - allow remaining tooth structure and restoration to withstand forces to long axis of tooth. 5 factors to resistance
- Removal of undermined surface enamel
Cavosurface margin should not terminiate on unsupported or undermined enamel to prevent its fracture. Undermined = unsupported = weakened
- Flat pulpal floor
Cup shaped cavity - rotation of the restoration (micromovement) results in a wedging effect on the supporting dentin bridge. Box shaped - pulpal floor perpendicular to the long axis of the tooth. **Cup can move due to wedging action, will eventually break or crack tooth structure.
Cavity prep depth
Amalgam - metal alloy - must have depth to have enough thickness to prevent fracture under load. Must be 1.5 mm at the least.
Well defined rounded internal line and point angles
• Placing line angles to delineate the walls • Sharp line angles are not recommended in any restoration • Sharp line angles act as stress concentration areas
Type of restorative material
Amalgam has low edge strength. Margin is of prime importance, in order to reinforce amalgam, need 90 degree angle from enamel to dentin.
Cavosurface angle
Angle formed by cavity walls and external tooth.
Butt-joint margin
90 degree amalgam margin. Exposed edge will break otherwise, 90 degree cavosurface angle.
Retention form
Design features of the cavity prep prevent dislodgement of the restoration by lifting or tipping forces. Amalgam does not bond to tooth structure, thus increasing the surface area of the walls that contacts the amalgam (increased friction).
Convenience form
Sufficient access to the cavity, to facilitate visibility and instrumentation of the cavity preparation and the insertion of the restorative material. Visibility - for complete removal of decay, access to prep for instruments, insertionof restoration material (1 mm is the smallest diameter of condenser). Narrowest portion of cavity must be at least 1 mm.
Finishing
Finishing the cavosurface margin (enamel margin) to prevent jagged or rough outline
•To achieve the best marginal seal
Debridement
Final step before restoration. Rinsing the cavity is done with air/water spray syringe and high suction evacuation. To wash away dental shavings and debris, dry out cavity.
Smear layer
Layer of dentinal shavings.
