Toothwear 1 Flashcards
Give a definition of tooth wear
The loss of mineralised tooth structures due to physical or chemophysical factors such as attrition, abrasion and erosion.
What are the 4 main causes of tooth wear?
- Intrinsic acids
- Parafunction (tooth on tooth contact)
- Mechanical factors (tooth brush abrasion, high RDA toothpaste, piercings)
- Dietary acids
RDA - relative dental abrasivity
What is abfraction and why did it used to be believed?
Contact between the upper and lower teeth causing occlusal forces.
Evidence now that the lesions on the base of the tooth is now caused by toothbrush abrasion.
What % of adults have tooth wear?
1/3
Fill in the gaps on enamel structure:
Enamel is one of the hardest structures in the human body. It has roughly ?% mineral content in the form of substituted calcium ?, 3% water and 1% organic tissue. (weak against acid due to the minerals - higher minerals = ? affected)
On tooth eruption, the outside layer of enamel, is a relatively disorganised structure, containing no prisms and hence is called the ‘aprismatic layer’ which is up to 100 microns deep. It has the highest ? content, containing fluoride and phosphate in the form of fluorohydroxyapatite. This layer has been shown to offer the greatest protection against both acid and mechanical challenges. - better protection on the outside due to higher fluoride, less calcium and no prisms
Acid can travel down the ? and cause softening once past the aprismatic layer so better to notice quickly so it isn’t destructed
Hydroxyapatite crystals are arranged in key-hole shaped prism structures which run ? to the outermost layer of enamel.
96%
hydoxyapitate
more
mineral
prisms
perpendicular
Fill in the gaps: dentine recap
Dentine is a permeable structure composed of ?% mineral, 20% organic material and 5% water. - high mineral so easily affected by acid
Closest to enamel is the ? dentine, which is roughly 15–30µm thick. Mantle dentine, similar to the aprismatic layer in enamel, is disorganised and only has a few thin, curved ?.
The bulk of dentine consists of ? dentine, a type I collagen-rich structure. This collagen network is moisture rich and elastic resulting in reduced hardness and ? susceptibility to wear, such as abrasion.
Peritubular dentin is formed within the lumen of the tubules. It is formed by a network of proteins and apatite crystals with no collagen fibrils. Peritubular dentin is highly mineralised making it more susceptible to an acid challenge. Once lost, the tube is ? which makes it easier to be affected by acid and erosive tooth wear&dentine hypersensitivity.
75%
mantle
tubules
intertubular
higher
wider
Explain what happens when teeth are exposed to acidic environment?
Minerals are released from the surface of the tooth, causing the outmost layer of the enamel to be softened.
Acid encounters a natural enamel surface and there is an initial breakdown of the interface between the prism and the interprismatic layer widening the prism. the prisms cores become richer in carbonate so are more susceptible to erosion.
Once the acid is not present, there is potential for the mineral to reform ionic bonds.
Explain acid dissociation in the mouth
Acid is in equilibrium in the mouth.
This exists between hydoxyapitiate Ca10(PO4)6(OH)2 and calcium, phosphate and hydroxide ions.
H+ environment will drive the tooth from solid to solution as ions are formed.
If a high concentration of calcium and phosphate ions are present, the hydoxapitiate will not dissolve.
Does erosion affect dentine or enamel more?
Dentine - lower mineral content
Give the differences between erosive tooth wear and caries
Erosive tooth wear:
- Involves softening of SURFACE enamel
- Acids are relatively strong, hydrochloric and citric acid
- Occurs on plaque-free surfaces
- outer surface is softest
- involves a widespread shallow unprotected area
- brushing hard can make it worse
Caries:
- Involves subsurface demineralisation
- acids are relatively weak, lactic acid
- plaque is a prerequisite (needed for caries to occur)
- Outer surface is harder due to fluoridation
- involves a localised deep protected area
- brushing will improve it
Anterior teeth
Toothwear signs in…
- early
- moderate
- severe
Early:
- loss of enamel surface anatomy produced round mesial and distal edges
- loss of perikymata, mamellons
- glossy smooth appearance
Moderate:
- loss of palatal tooth structures reduces support along the incisal edge
- the tooth becomes shorter
- distinct buccal lesions
- fracture of enamel
Servere:
- shortening and chipping
- translucency on edges
- buccal lsions
- smooth and glossy surfaces
Posterior teeth:
Toothwear signs in…
- early
- moderate
- severe
Early:
- Rounding of cusps tips
- loss of morphology such as deep fissures
- shiny and glossy
Moderate:
- Cupping on occlusal surfaces
- increasing exposure of yellow dentine
- changes to shape of tooth
- shortening of the clinical crowns
Servere:
- lesions start to merge
- extensive dentine exposure
- shortened clinical crowns
- occlusal changes with alveolar composition
What is the BEWE?
Basic erosive wear exam.
Grade all the teeth from 0 to 3
Divide the tooth in 6 parts
Add up all the scores and see what you get:
<6 = just need normal oral hygiene, routine check ups 7-12 = above and fluoride measures, avoid restorations and repeats every 3 months check ups >13 = above and consider restorations
