ICP-17 Occlusal and Approx Cavity Prep of PRIMARY TEETH Flashcards
Why should we restore children’s teeth
- Eradicate disease and restore health
- To give child simplest form of treatment - easier to accept that pulpotomy or extraction
- Prevent pain and suffering
- Avoid infection
- Maintain arch length - presence space needed for eruption of permanent teeth
- Restore function
- Psychological benefits
- Quality of life
What are the differences between primary and permanent molars
- Primary = thinner enamel
- Primary = greater thickness of dentin over pulpal wall at the occlusal fossa
- Primary = higher pulpal horns, especially mesially, pulp chambers are proportionately larger
- Primary = more pronounced cervical ridges, especially on the buccal aspect of the first primary molars
- Enamel rods at cervix slope occlusal instead of gingivally
- Primary molars have a markedly constricted neck
- Roots of primary teeth = longer and more slender compared to crown size
- roots of primary molars flare out near the cervix
What must be taken into account when taking the decision to restore a child’s tooth
- developmental stage of child
- Caries risk assessment
- oral hygiene
- Parent compliance
- Child compliance
Name some restorative materials that can be used to restore primary molar teeth
- Composite
- GIC
- RMGIC
- Compomers (Polyacid modified composite resin)
- Stainless steel crowns (SSCs)
What are the advantages of choosing composite resin when restoring deciduous teeth
- Aesthetics
- Minimally invasive
- Can be used for PRRs/Fissure sealants/occlusal/small approx. in deciduous molars not extending beyond proxima line
- Approx. in permanent molars no more than one third of buc-lin intercuspal width
What are the disadvantages of choosing composite resin when restoring deciduous teeth
- Polymerisation shrinkage can occur
- Need good isolation/patient cooperation
- Technique sensitive and more time consuming to place
- Not suitable for large multiple surface restorations in posterior primary teeth
What are the advantages of choosing GIC when restoring deciduous teeth
- Chemical bonding to enamel and dentine
- thermal expansion similar to tooth
- biocompatibility
- uptake and release of fluoride
- less moisture sensitivity compared to resin composite
- Good for a shit ton of thing like: luting cement SSC, repainting restorations, cavity base and liner etc
What are the disadvantages of choosing GIC when restoring deciduous teeth
- Not as wear resistant as resin composite
- Not as good aesthetics as resin composite
- RMGIC has better wear resistance
What are the advantages of choosing SSCs when restoring deciduous teeth
- Durable
- Relatively inexpensive
- Minimal sensitivity
- Full coronal coverage
- good for hypo plastic teeth/extensive caries/Hall Tech/multiple lesions
What are the disadvantages of choosing SSCs when restoring deciduous teeth
Aesthetics
What are the considerations that you need to make in cavity preparations
- Risk of pulpal exposure as pulpal horns are higher in primary teeth
- Buccal and lingual wall should be parallel to the outer tooth surface
- Isthmus width should be 1/3 the intercuspal distance
- No bevel at the gingival rest
What is an isthmus
Central portion of the cavity preparation on the occlusal surface of a bicuspid or molar
Where is the isthmus found in a class I preparation
This is located between the mesial and distal dovetails
Where is the isthmus found in a class II preparation
This is located between two proximal flares or one proximal flare and dovetail
What are some important point to remember when preparing occlusal cavity
- Preserved marginal ridge
- Isthmus width 1/3rd of intercuspal distance
- Outline form of isthmus showing smooth flowing curves including all pits and fissures
Describe the process and features of a good external outline of a primary tooth cavity prep
- Gain access with a 330 bur in the deepest pit
- Extend to remove all caries and include susceptible pits and fissures
- Smooth outline
- Contour outline parallel to messiah and distal ridges (oblique ridge in maxilla)
- Width to be less than 1/3 of occlusal table
Describe the features of a good internal outline of a primary tooth cavity prep
- 0.5mm into dentine (1mm enamel + 0.5mm dentine)
- Rounded pulpal line angles
- Cavo-surface 90 degress
- Lateral wall undercuts
What is the approx. occlusal and proximal depth of approximal cavities
- 5mm occlusally
2. 5mm. approximally
AY BAWS CAN I HABE DE NOTE PLZ
Proximal extension should be 90 degrees to the axial surfaces of the tooth to avoid digging into pulp
Describe the floor of the proximal box of an approximate cavity
Must be flat or slightly concave gingival, not bevelled
Describe the shape of the pulpoaxial wall of the approximate cavity
The wall follows the contour of missing tooth surface
Describe the buccal and lingual walls of the proximal box thing of approximate cavities
Diverge towards the gingival margin of the box
How do you start the prep of the proximal box of an approximate cavity
- Start from marginal ridge, use slight pendulum motion to widen entry point and gradually move deeper into tooth preparing the prox box to depth of 2.5mm and width of 1.5mm at base and 1mm at top of cavity
