Enamel Flashcards
What is the primary mineral composition of enamel?
Contaminated apatite mineral around a proteinaceous matrix
Apatite is a group of phosphate minerals, and in the context of enamel, hydroxyapatite is the primary form.
What is the significance of contaminants in the hydroxyapatite lattice?
They can destabilize or stabilize the lattice
For example, carbonate can destabilize while fluoride and magnesium can stabilize.
What is the flexural strength range of enamel?
30-50 MPs
Flexural strength measures the ability of a material to resist deformation under load.
How does the prismatic structure of enamel affect load distribution?
Prisms are always perpendicular to the surface, channeling load down into dentine
This design helps avoid stress concentration on the brittle outer enamel shell.
What is the role of fluoride in enamel?
Fluoride can reduce mineral dissolution in the presence of acid
Topical application of fluoride is more effective than systemic fluoride for caries prevention.
What is Amelogenesis Imperfecta (AI)?
A heterogeneous group of genetic disorders characterized by defects in enamel formation
AI occurs without any generalized or systemic diseases.
What is the prevalence range of Amelogenesis Imperfecta?
1:700 to 1:14,000
This indicates the number of individuals affected by AI in the general population.
What are the components of the diagnosis for Amelogenesis Imperfecta?
Clinical appearance, mode of inheritance, and biochemistry
These factors are important for clinical management and genetic counseling.
What is the effect of systemic fluoride on dental health?
It increases the fluoride content of teeth, which may result in fluorosis
Fluorosis is a condition caused by excessive fluoride intake during tooth development.
What is the difference between caries and erosion?
Caries is caused by weak acids from bacterial metabolism, while erosion is caused by strong intrinsic or extrinsic acids
Erosion is a surface phenomenon and is not reversible.
What is the role of saliva in tooth eruption?
Saliva is supersaturated with respect to calcium and phosphate, providing a unique opportunity to mineralize and strengthen teeth
This is an ideal time for topical fluoride application.
What is the significance of the Tomes process in amelogenesis?
Each Tomes process is responsible for the formation of an enamel prism/rod
Prisms/rods run from the Amelodentin Junction (ADJ) to the tooth surface.
What is the main treatment approach for amelogenesis imperfecta?
Protection against wear and aesthetic restoration
Treatments may include gold, composite, porcelain, or acrylic stabilization splints.
Fill in the blank: The ‘head-of-fish’ crystalites in enamel are ________ packed in the long axis of the prism.
densely
This structure aids in the mechanical properties of enamel.
True or False: Enamel can last a lifetime without any claims for other dental materials.
True
Enamel is unique in its durability compared to other dental materials.
What is the relationship between fluoride concentration and dental caries experience?
No significant difference in decay susceptibility between fluoridated and non-fluoridated areas
Fluoride should be available topically for the lifetime of the tooth.
What is the most effective way to apply fluoride for caries prevention?
Topical application in the aqueous environment around the teeth
This method ensures fluoride is readily available to the enamel surface.
What are perikymata in enamel?
Remnants of the Tomes process at the tooth surface
They reflect the growth patterns of enamel.
What is amelogenesis imperfecta?
A genetic disorder affecting the development of enamel on teeth
Affects the structure and appearance of teeth.
What bonding agent enhances composite to amelogenesis imperfecta enamel?
Sodium hypochlorite (NaOCl) after etching
Increases bond strength in various studies.
What is the effect of resin infiltration on hypomineralised enamel?
It improves microshear bond strength of resin composite
A key factor in restoring hypomineralised enamel.
What are the three main goals of treating amelogenesis imperfecta?
- Preventive care
- Protect against wear to maintain function
- Treat aesthetics
What are the requirements for all cavity margins in dental restorations?
- Caries-free
- Free of contact with adjacent tooth
- Accessible for cleansing
What is the ideal cavo-surface angle for cavity margins?
Close to 90 degrees
Important for maximizing strength and minimizing leakage.
What does the acid etching technique do?
Increases the adhesion of acrylic filling materials to enamel surfaces
Developed by Dr. Michael Buonocore in 1955.
What is posterior composite made of?
- Resin (based on BIS-GMA)
- Filler (usually quartz)
- Silane bonding agent
What year was BIS-GMA developed?
1963
By Rafael ‘Ray’ Bowen DDS.
How does posterior composite bond to enamel?
Through a micromechanical bond to etched enamel
Requires optimal flow properties of unfilled resin.
What is the primary mechanism for teeth whitening?
- Clean the enamel
- Oxidise the enamel
- Remove and replace enamel with restorative material
What is the role of hydrogen peroxide in bleaching?
Breaks down to produce oxygen free radicals that react with intrinsic stains
Highly reactive and effective in stain removal.
What is the legal limit for hydrogen peroxide in tooth whitening products?
No more than 6% hydrogen peroxide
Regulated by GDC for cosmetic purposes.
What are the five types of acids used for etching enamel?
- 35-40% orthophosphoric acid
- 2% acetic acid
- 10% metaphosphoric acid
- 30% hydrochloric acid
- 35-40% citric acid
Why is it critical to remove caries at the dentine-enamel junction?
To prevent unsupported enamel and early breakdown of the restoration margin
Ensures durability of dental restorations.
What is the effect of fluoride on enamel remineralization?
Stabilizes the hydroxyapatite lattice
Helps in preventing further demineralization.
How does the structure of mature human enamel relate to cavity design?
Unsupported enamel should be removed before cavity obturation
Ensures a robust restoration.
What is the definition of mature human enamel?
A crystalline structure of carbonate depleted apatite
Essential for understanding enamel’s properties.
How does the chemistry of human enamel affect the caries process?
- Carbonate replaces hydroxyl ions to inhibit apatite dissolution
- Fluoride destabilizes the apatite lattice in demineralization
- Carbonate is preferentially lost in early demineralization
