Abrasion and abfraction

Question 1

Define abfraction, abrasion, attrition, corrosion

Answer 1

• Abfraction: Pathological loss of hard tooth substance caused by biomechanical loading forces. Such loss is thought to be a result of flexure and chemical fatigue degradation of enamel and/or dentin at some location distant from the actual point of loading
• Abrasion: Wearing away of surface material between tooth and exogenous agent
• Attrition: Wear caused by tooth to tooth friction
• Corrosion: Tooth surface loss by chemical or electrochemical action i.e. chemical dissolution of tooth (endogenous and exogenous agents)

Question 2

Define non- carious cervical lesions (NCCL)

Answer 2

• Describes a dental hard tissue defect of unknown origin
• Two distinct variations: wedge-shaped lesions and saucer-shaped lesions
• Recognising CEJ is a ‘very vulnerable’ region
• 100% of wedge-shaped and 70% of saucer-shaped teeth showed evidence of additional abrasion (incisal and/or occlusal surface)
• 11% of wedge-shaped and 39% saucer-shaped lesions had tiny grooves parallel to the cemento-enamel junction (CEJ)
• 88% of all teeth had ‘dead tracts’ (empty dentinal tubules as result of deterioration of odontoblastic processes)
• 48% of the teeth showed presence of sclerotic dentin immediately adjacent to the defect

Question 3

Briefly discuss findings related to wedge- versus saucer-shaped lesions

Answer 3

• Chemical degradation of surface by bacteria could weaken the CEJ, further influenced by low pH values
• Higher % of plaque makes abrasion theory less plausible, as less plaque would be present with vigorous toothbrushing
• Attrition, rather than abrasion, may be major factor in wedge-shaped lesions
• Presence of grooves to CEJ could support toothbrush abrasion in saucer-shaped lesions
• Border of defects more rounded in saucer-shaped- possibly due to erosion and toothbrushing

Question 4

Discuss the principle and secondary factors related to toothbrushing that contribute to recession

Answer 4

• Subjects using a manual toothbrush (MTB) had greater recession after 12 months than those using powered toothbrushes (PTB)

13 cross-sectional studies identified gingival recession associated most frequently with:
• Toothbrushing frequency
• Horizontal or scrub TB method
• Bristle hardness
• Toothbrushing duration
• Frequency of changing toothbrush

Question 5

List the three main categories of the multifactorial nature of tooth surface lesions

Answer 5

1. Stress
2. Biocorrosion
3. Friction

Question 6

Explain endogenous stress as a multifactorial nature of tooth surface lesions (3)

Answer 6

• Parafunction
• Occlusion (premature contacts, occlusal loading)
• Hard foods

Question 7

Explain exogenous stress as a multifactorial nature of tooth surface lesions (4)

Answer 7

• Habits (biting on things like nails and pens)
• Occupation for example, playing wind instruments and/or using teeth to hold things
• Dental appliances (dentures, ortho)
• Type of stress: static or cyclic

Question 8

Explain endogenous biocorrosion as a multifactorial nature of tooth surface lesions (3)

Answer 8

• Plaque (acidogenic bacteria and proteolytic bacteria)
• Gingival crevicular fluid
• Gastric juices (GORD)

Question 9

Explain exogenous biocorrosion as a multifactorial nature of tooth surface lesions (5)

Answer 9

• Acidic beverages
• Occupational for example, exposure to acidic gases
• Electrochemical - piezoelectric effect in dentine. This is when the dentine develops an electric charge as a result of mechanical stress

Proteolysis:
• Enzymatic lysis (caries)
• Proteases (pepsin, trypsin)

Question 10

Explain endogenous friction as a multifactorial nature of tooth surface lesions (2)

Answer 10

• Parafunction

* Eating hard foods

Question 11

Explain exogenous friction as a multifactorial nature of tooth surface lesions (6)

Answer 11

• Overusing dental hygiene instruments
• Detrimental habits like chewing on objects, or using teeth to open things
• Occupational risks
• Dental appliances
• Mutilating teeth (rituals)
• Erosion (due to liquid)

Question 12

Explain how OHTs can help people with abrasion (3)

Answer 12

• Revise/correct harmful brushing habits (Eg. excessive force, technique, electric TB?)
• Recommend patient use less abrasive toothpastes (Eg. avoid whitening toothpastes)
• Advise patients to avoid brushing within 30 minutes following extrinsic or intrinsic acid attack

Question 13

Explain how OHTs can help people with erosion (6)

Answer 13

• Reduce dietary acid intake (frequency & duration) or consume these foods with meals
• Avoid or decrease intake of sports drinks, carbonated and acidic alcoholic beverages
• Suggest the use of a straw to avoid bathing teeth
• Following consumption of acidic foods/drinks, eat hard cheese, use baking soda rinse or sugarless chewing gum
• Recommend high Fluoride toothpaste or mouth-rinses
• Recommend seeing GP for those struggling with alcohol or drug use, eating disorders

Question 14

Explain how OHTs can help people with attrition and abfraction (3)

Answer 14

• Decrease consumption of alcohol and caffeine containing beverages
• Consult with dentist regarding need for occlusal adjustments or night guard (splint)
• Consult with dentist with regards to referral for orthodontic treatment, cognitive and behaviour therapies, etc

Question 15

Discuss why ‘erosion’ might not be ideal term to describe the dissolution of tooth substance

Answer 15

Using new terminology that describes mechanisms involved in tooth surface lesions to improve communication with other sciences