6. Tooth wear I Flashcards
LOS
What is tooth wear?
- cumulative surface loss of mineralized tooth substance due to physical or chemo- physical processes (dental erosion, attrition, abrasion).
- NOT CONSIDERED TO BE AS A RESULT OF CARIES, RESORPTION OR TRAUMA
what is erosive tooth wear?
tooth wear with dental erosion as primary etiological factor
diff between tooth wear + erosive tooth wear?
TIP
- if you see severe tooth wear always look for the acid causing it, especially if the patient is young
What is abfraction?
- This is a non-carious tooth tissue loss that occurs along the gingival margin
- It is a mechanical loss of tooth structure that is not caused by tooth decay, located along the gum
line - Poor evidence base that occlusal forces cause tooth wear
- Good evidence base that occlusal equilibration is ineffective
- No fractures detected under Scanning Electron Microscopy or Confocal Laser Scanning Microscopy
- Abrasion scars detected in 70-100% of lesions
prevalence of tooth wear in adults?
1
UK
2
Europe
1
- 77% of dentate patients have tooth wear into dentine in their anterior teeth
- 15% showed moderate wear
- 2% showed severe wear
(UK dental health survey 2009)
2
- Roughly 1/3 of all European adults aged 18-35% have one surface with moderate tooth wear
- 3% have severe tooth wear
prevalence of tooth wear in children?
- 1,308 children were examined in Birmingham at the age of 12years and re-examined 2years later
- New or more advanced lesions were seen in 27% of the children over the study period
- 12% of erosion-free children at 12years had developed the condition over the 2years period
- severe tooth wear can be sign of acid reflux or due to diet
- important to start prevention education early
why is the prevalence of tooth wear increasing?
- fruits are available out of season
- more snacking throughout the say
- more soft drinks consumed
- flavourings in water
recap on enamel composition + structure?
- Enamel is one of the hardest structures in the human body
- roughly 96% mineral content in the form of substituted calcium hydroxyapatite, 3% water and 1% organic tissue
(weak against acids due to high mineral content) - On tooth eruption, 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
- has the highest mineral 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 as it doesn’t have a prism structure
- Hydroxyapatite crystals are arranged in key-hole shaped prism structures which run perpendicular to the outermost layer of enamel
(as prisms, shaped like tube so acid can run down + cause a little bit of subsurface softening)
recap on dentine composition and structure
- Dentine is a permeable structure composed of 75% mineral, 20% organic material and 5% water
- Closest to enamel is the mantle dentine = roughly 15–30µm thick
- Mantle dentine = similar to the aprismatic layer in enamel, is disorganised and only has a few thin, curved tubules
- bulk of dentine consists of intertubular dentine, a type I collagen-rich structure
- This collagen network is moisture rich and elastic resulting in reduced hardness and higher susceptibility to mechanical wear, such as abrasion + attrition
(thus more likely to wear than enamel) - 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
- as if loose peritubular dentin then tubule is widened hence more susceptible to acid challenge + hypersensitivity)
Pathophysiology of teeth
- When teeth are exposed to an acidic environment, minerals are released from the surface causing softening of the outermost layer between 0.2 and 2µm thick
- When acid encounters a natural enamel surface, there is initial breakdown of the interface between the prism and interprismatic layer widening the prism (12)
- Thereafter, the prism cores are richer in carbonate, making them more susceptible to erosion
- Liquid can move through enamel prisms of the teeth causing subsurface softening
- In the absence of further erosive challenges or mechanical removal, there is possibility for minerals to form new ionic bonds in the acid softened enamel
- BUT this needs to be in very early stages of enamel
chemistry of dental erosion VS caries
CARIES
- Initial lesion has a small surface area
- Generally in protected areas with potential for localised application of remineralising agents
- Deep lesions
- Outer surface is generally harder due to fluoridation
- Increased oral hygiene results in decreased disease progression
EROSION
- Initial lesion has a large surface area
- No protection from environment when demineralised
- Wide shallow lesions
- Outer surface is softest
- Increased oral hygiene may result in increased disease progression
summary of what happens during mild acid challenges?
- acid causes outflow of minerals
- this leaves behind a softened surface which is more at risk to physical forces eg. brushing
- fluoride + calcium ions can be incorporated back into tooth structure, rehardening it + making it less susceptible to future acid challenges
- Enamel is very mineralised so is strong in absence of acid challenge, mechanical wear needs high aggression to remove
- Dentine however is much easier to remove with mechanical wear, even without acid although this increases rate
how does tooth brushing affect tooth wear?
- Toothbrushing with a force of 400g (normal brushing force is 100-300g), has been shown to remove dentine and increase the number of patent dentine tubules.
- Attritional forces have the capacity to remove exposed dentine. This is worse on acid softened dentine
ACID EROSION VS DENTAL CARIES features
EROSIVE TOOTH WEAR
- Involves “softening” of surface enamel
- Acids are relatively strong
- Occurs on plaque-free surfaces
- HCl (intrinsic, gastric origin) and citric acid (extrinsic, dietary origin) are main acids involved
- Outer surface is softest
- Involves a widespread shallow unprotected area
- Brushing can exacerbate erosive tooth wear
CARIES
- Involves subsurface demineralization
- Acids are relatively weak
- Plaque is a prerequisite
- Outer surface is generally harder due to fluoridation
- Involves a localized deep protected area
- Brushing will often improve caries
For both it is important to find all of the risk factors, examine the diet and examine oral hygiene
key features to look out for for tooth wear?
- Early identification is key
- key teeth to watch = maxillary central incisors and the lower first molars
- Usually clean, plaque free surfaces
- early stages can be difficult to distinguish with unworn teeth
- as lesions progress, it becomes easier to identify, but tooth wear will be worse
anterior teeth - what to look for in early erosion tooth wear?
- Loss of enamel surface anatomy produces rounding of mesial and distal edges and along the incisal edge
- Loss of perikymata, mamellons and pronounced cingulum features
- A glassy smooth appearance on the facial/buccal surfaces
anterior teeth - what to look for in moderate erosion tooth wear?
- Loss of palatal tooth structure reduces support along the incisal edge
- The tooth becomes shorter
- Distinct buccal lesions can also occur and grow in size
- As the condition progresses the lack of support leads to fracture of the enamel
Severe ETW: Anterior teeth features
- Technically classified as severe erosive tooth wear
- prevention is still effective and a focus and can stop the restorative cycle
- Easy to spot some exposed dentine
but some may be largely enamel - Rehab of teeth are quite difficult
- As it progresses Darkening from underlying dentine
- grooving/ wear along incisal edge
- shortening of clinical crowns
very severe ETW: Anterior teeth features
- really hard to restore
- patients biting in wrong areas
Early ETW: Posterior Teeth features?
- Rounding of cusp tips
- Loss of morphology such as distinct ridges, deep fissures
- Surfaces become shiny and glossy
- loss of staining
Moderate ETW: Posterior teeth features?
- Cupping on occlusal surfaces
- Increasing exposure of “yellow” dentine
- Changes to the shape of teeth
- Shortening of the clinical crowns
- cupped out lesions indicate acids - either from stomach or diet
Severe ETW: Posterior Teeth features
- Lesions start to merge
- Extensive dentine exposure
- Shortened clinical crowns
- Occlusal changes with alveolar compensation
- Prevention may slow progression and avoid the restorative/maintenance cycle
- no restorative space
- very very difficult to restore
Performing the BEWE?
- Divide patient’s dentition into sextants
- Assign a BEWE score to the tooth area in each sextant most severely affected by erosive tooth wear
- calculate your patient’s cumulative score
What are BEWE scores?
_always go for the worst surface in that sextant
0
- no erosive tooth wear
- patients over 30 usu don’t score zero
1
- Initial loss of (enamel) surface structure
- no distinct defect
- but definite signs of erosive tooth wear happening
2
- Distinct defect forming, hard tissue loss of <50% of the tooth surface area
3
- Hard tissue loss of >50% of the surface area (dentine may be visible)
How to decide BEWE score?
how to calculate patients cumulative score?
- a 3 in a sextant = high risk
- Using the diagram assign and calculate your patient’s total score across sextants
- Low: 6 or lower
~ Oral hygiene, dietary assessment
~ Routine maintenance and observation
~ Repeat at 2-year intervals - Medium: 7-12
~ Oral hygiene, dietary assessment
~ Routine maintenance
~ Fluoride measures
~ Avoid restorations
~ Repeat at 3-6 month intervals - High: 13 or over
~ As above with the exception of the
following:
~ Consider restorations
Example BEWE
- if not sure of score always score down, NOT up
