Cariology Flashcards
What is the definition of caries?
Demineralization and loss of substance of the hard tissues of the teeth, leading to continued destruction of enamel and dentine, and cavitation of the tooth.
What 3 factors are involved in caries formation?
Host and saliva, diet, and microflora
What are the 5 risk factors in caries development?
- Pathogenic plaque bacteria
- Poor oral hygiene
- Reduced salivary flow/ Systemic conditions
- Bad dietary habits
- Anatomic variations: hard to clean areas
What are the 5 protective factors from caries development?
- Non-pathogenic plaque bacteria
- Good oral hygiene
- Adequate salivary flow
- Good dietary habits
- Fluoride, xylitol
What are the 3 functions of enamel?
- Provides hard, durable surface for teeth
- Forms a protective cap for the dentin and pulp
- Gives shape of teeth
What are the 2 basic structural units of enamel?
- Cylindrical enamel rods
2. Surrounding interrod enamel
What are the 2 protective mechanisms of enamel?
- Tightly compressed crystals- little or no space for acid penetration
- Renewal of calcium, phosphates, and fluorides
What is the result of enamel’s protective mechanism?
The dynamics of demineralization can be stopped or reversed.
What is enamel?
Acellular and predominantly mineralized epidermal tissue.
What is the function of calcium ions in enamel?
Transported as “seeds” of hydroxyapatite. They form a site for cystallization. Crystals enlarge and supplant organic matrix.
What is the building blocks of enamel crystal?
Molecular units of hydroxyapate
What can diffuse through the semipermeable enamel?
Various fluids, ions, and low-molecular-weight substances.
True or False:
Enamel is capable of self-repair.
False
Incapable of self-repair, but capable of remineralization.
What is the process of remineralization?
After initial stage of mineral loss, enamel fills void with new mineral: alterations in the dynamics of mineralization process through the incorporation of fluoride from various sources.
What is the process of initial demineralization?
- Enamel exposed to acids for a brief time
- Spacing and divergent orientation of crystals result in between rod and interrod enamel
- Makes enamel rod differentially soluble
What characteristic of enamel makes it more susceptible to acid penetration?
Certain areas of our enamel does not have perfect alignment: more susceptible.
What component of enamel are most susceptible to demineralization and first to be solubilized?
Carbonated components of the crystal.
Enamel’s crystalline makeup and rigidity/brittleness makes it more susceptible to what 4 things?
- Acid demineralization
- Attrition (“wear”)
- Erosion/abrasion
- Fracture
Enamel’s hardness is ___ times that of dentin’s.
5
What are the 5 functions of dentin?
- Forms bulk structure of the tooth
- Elastic foundation for the enamel
- Provides color (pale yellow)
- Protective barrier and chamber for vital pulp tissues
- Responds to external thermal, chemical, and mechanical stimuli
Which is harder, dentin or bone?
Dentin is slightly harder than bone, but not as hard as enamel.
Root dentin is covered with ________ and crown dentin supports the _________.
Covered with cementum and supports the enamel.
What makes up dentin?
45-50% inorganic apatite crystals
30% organic matrix
What is the function of intertubular dentin?
It is the structural component of the hydroxyapatite-embedded collagen matrix. Forms the bulk of dentin structure.
Where is the peritubular dentin and what are its components?
Limited to the lining of the tubule walls. Has little organic matrix but densely packed with minuscule apatite crystals.
What is the difference in composition between enamel and dentin?
Inorganic hydroxyapatite: E-96% D- 45-50%
Organic matrix: E- 1% D- 30%
Water: E- 4% D- 25%
*Enamel:Nail::Dentin:Skin underneath
What is the affect of time on intertubular dentin and peritubular lining?
Primary intertubular dentin remains dimensionally stable, but peritubular lining gradually increases in width over time.
*pulp chamber gets smaller with age
When is primary dentin formed and under what conditions does it continue to form?
It is the first dentin to be formed (by odontoblasts).
Formation continues even after tooth is matured, as long as root apex remains undeveloped and open.
When is secondary dentin formed and what are the effects of its formation?
Formed as tooth is maturing. Reduces the volume of the pulp chamber, pulp horns, and root canals.
Where is the tertiary dentin formed and what are its functions?
Formed at the dentin-pulp interface. Compensates for the loss of peripheral dentin from caries or injury. May provide superior pulpal seal against noxious diffusion thru tubules.
*The reactionary/reparative dentin.
In what sequential ways does dentin respond to injury or active caries?
- Immediate inflammatory response
- Increased outward flow rate of tubular fluid
- Passage of plasma proteins into the dentinal fluid
- Direct immune response to bacteria.
What happens during dentin’s immediate inflammatory response?
Pulpal vasodilation, increased blood flow, and increased interstitial fluid pressure.
Which two plasma proteins are passaged into the dentinal fluid during dentin’s inflammatory response?
Albumin and immunoglobulin passaged between the odontoblast cells into the dentinal fluid.
True or False
The diffusion of exogenous stimuli to the pulp is limited.
True and it forms direct immune response to bacteria.
What is tubular sclerosis?
Dentin reaction against caries by deposition of mineral within the dentin tubules, resulting in gradual occlusion (clogging of passageway)
How does tertiary dentin respond to caries or trauma?
Odontoblasts form tertiary dentin at the pulp-dentin border as a response to stimulus.
What happens to dentin-pulp complex in moderate and slow developing stimuli?
- It has time to hyper mineralize or sclerose the tubule channels.
- Can add new tertiary dentin at the pulp-dentin junction. (PDJ)
What happens to dentin-pulp complex in trauma/ rapid advance of caries lesion/ deep cavity preparation?
- Numerous open tubules –> vulnerable pulp
- Bacteria reaches level of PDJ
- Pulpal necrosis
What is pulp?
Viscous CT of collagen fibers and organic ground substance supporting the vital cellular, vascular, and nerve structures of tooth.
What are the functions of pulp?
- Formative: generats dentin (dentinogenesis)
- Nutritive
- Sensory: Nociception (neural processing of noxious stimuli: pain)
- Protective
How does pulp provide nutrition to the teeth?
Provides 1. vascular supply and 2. ground substance transfer for metabolic functions and maintenance of cells and organic matrix.
How does pulp protect the teeth?
Coordinates inflammatory, antigenic, neurogenic, and dentinogenic responses to injury and noxious stimuli.
What is the composition of pulp?
75% water and 25% organic material
How is the pulp vascularized?
Through one opening (apical foramen) and it is completely surrounded by rigid dentinal walls.
What are the advantages or disadvantages of pulp?
Advantages: protected and isolated. Sensitive but resilient tissue with great potential for healing.
Disadvantages: Limited collateral blood supply. Limited expansion space (bc of enamel) for swelling during typical inflammatory response–> pressure.
What are the zones of the pulpal tissue?
- Peripheral odontoblastic layer
- Cell-free zone
- Cell-rich zone
- Pulp core
What is the process of demineralization?
- Bacteria feed on carbohydrates producing acid as byproduct and lowering pH
- Acids diffuse into tooth
- Acids dissolve carbonated hydroxyapatite crystal
- Subsurface lesion (partial demineralization)
- Cavitation
Which step of demineralization is reversible and how is it reversed?
Subsurface lesion step. Reversed by addition of fluoride, phosphate, and calcium.
Which minerals are lost during demineralization?
Calcium, phosphate, and carbonate.
What is the result of remineralization?
Hydroxyapatite turns into fluorohydroxyapatite, which is more stable and less acid-soluble crystals than hydroxyapatite.
What is cavitation?
Breakdown of outer enamel due to caries, mechanical injuries (mastication), microtraumas (wear), iatrogenic trauma (careless probing). At this point, remineralization is not guaranteed.
Why is cavitation conducive to further demineralization?
Difficult to remove biofilm out of cavitated area.
What is the evolution of caries?
- Adhesion
- Colonization
- De- & Re-mineralization
- White spot
- Enamel lesion
- Dentin lesion
- Pulpal lesion
What is the result of greater demineralization than remineralization?
White spot lesion
At point is demineralization still reversible?
White spot lesion. Once evolved into enamel lesion, bacteria more protected leading to cavitation.
True or False
Caries is caused by commensal organisms not infecting invaders
True
Commensal organism: normal bacteria flora in mouth that normally does no harm.
Where does dental caries take place?
On any tooth surface where plaque is allowed to develop e.g. enamel, dentin, and cementum
True or False
Microbial adhesion/colonization is vital to have caries and cause disease
False
Adhesion/colonization is vital but not necessarily sufficient to cause disease
What is the carious process once the biofilm forms at tooth surface?
- Bacteria ferment carbs and produce acid
2. Acids lowers pH ( longer periods of demineralization and not enough time for remineralization
What is the critical pH threshold for enamel? For dentin?
Enamel: 5.5
Dentin: 6.5