L10 Non-Carious Destruction of Teeth

Question 1

What are the 4 types of physical non-carious destruction?

Answer 1

• Fracture
• Attrition
• Abrasion
• Iatrogenic

Question 2

Describe crown fractures.

Answer 2

• Common
• Frequently seen in children
• 70-90% maxillary teeth
• Affects predominantly upper anterior teeth, non-vital teeth (more brittle) and teeth with large restorations
• 9 classes of tooth fracture

Question 3

Describe how root fractures may repair themselves.

Answer 3

Deposition of osteodentine: a bone-like material deposited, no tubules and contains osteocytes

Question 4

Describe attrition.

Answer 4

• Tooth on tooth contact
• Affects occlusal, incisal and interproximal surfaces
• Increases with age
• Presents clinically as a small polished facet on a cusp tip or ridge, or slight flattening of an incisal edge
• Leads to exposed dentine, exposed tubules can lead to dentinal sclerosis (calcification) and reparative dentine formation

Question 5

What factors contribute to the variations in prevalence and severity of attrition?

Answer 5

• Men usually show more attrition (stronger masticatory forces?)
• Differences in coarseness of diet
• Differences in chewing patterns
• Bruxism
• Soft teeth e.g. hypoplasia, amelogenesis imperfecta, dentinogenesis imperfecta

Question 6

How may attrition be caused on the interproximal surfaces?

Answer 6

Teeth move in the socket during mastication, thus producing wear of interproximal contact points.

Question 7

Describe abrasion.

Answer 7

• Pathological wearing of tooth substance by an abnormal mechanical process
• Improper use of floss, pipe smokers, opening hair grips, biting cotton, poor toothbrushing technique, abrasive toothpaste

Question 8

How does abrasion present clinically?

Answer 8

• V-shaped or wedge shaped ditch on the root site of the amelo-cemental junction, exposed dentine will be highly polished
• Remarkable wear of cementum and dentine, often after gingival recession has uncovered cementum

Question 9

What is another cause of V-shaped defects other than abrasion?

Answer 9

Abfraction

Question 10

Describe abfraction.

Answer 10

• High occlusal load causes large stress concentrations in cervical regions of teeth
• These stresses may be high enough to disrupt bonds between HAP crystals thus causing loss of cervical enamel

Question 11

Describe iatrogenic causes of tooth destruction.

Answer 11

• With laryngoscope during intubation
• Misuse of elevators
• During cavity prep: damage to adjacent tooth, overcutting cavity, pulp exposure

Question 12

What are the underlying causes of erosion?

Answer 12

• Dietary acid
• Industrial erosion
• Vomiting
• Idiopathic (unknown cause)

Question 13

Describe erosion.

Answer 13

Chemical destruction of teeth.

• Loss of tooth substance due to the action of acid
• May involve chelating agents (which remove calcium and phosphate ions from teeth)
• Affects buccal, labial and palatal surfaces
• Produces shallow scooped out depressions with smooth highly polished surface

Question 14

How do dietary acids cause erosion?

Answer 14

• Citric acid is most destructive

- Present in sugary drinks, citrus fruits, energy drinks

Question 15

What is industrial erosion?

Answer 15

• Acid in the form of fumes, mist and particles
• Incisal third most commonly affected, lips cover the rest of the tooth
• Not common now due to health and safety laws

Question 16

How does vomiting cause erosion?

Answer 16

• Gastric acid erodes teeth
• Affects lingual and palatal surfaces
• Commonly present in patients with bulimia or gastric and duodenal ulcers

Question 17

How can cellular activity lead to non-carious destruction of teeth?

Answer 17

Cellular activity/Resoprtion:

• Destruction of tooth tissue due to activity of neighbouring tissue
• Odontoclasts resorb tooth tissue

Question 18

What are the 2 types of resorption?

Answer 18

External resorption: starts outside of the tooth, usually caused by a tissue reaction in peridontal or pericoronal tissue

Internal resorption: begins centrally within the pulp

Question 19

How may a resorped tooth present clinically?

Answer 19

• No early clinical features
• May have a pink hue to the crown (vascular pulp)
• May fracture

Question 20

What type of teeth are more prone to resorption?

Answer 20

• Avulsed and replanted teeth

- Root filled teeth

Question 21

How will resorped teeth present radiographically?

Answer 21

• Irregular areas of radiolucency

Question 22

What are the histological features of resorped teeth?

Answer 22

• Resorbed area of dentine replaced by fibrous CT
• Often evidence of repair with bone like material (ostoedentine)
• Multi-nucleated osteoclast-like cells in lacunae on surface of resorbed dentine (odontoclasts)

Question 23

Describe internal resorption.

Answer 23

• Uncommon
• Begins in the pulp
• Possibly related to an usual inflammatory hyperplasia of the pulp
• This condition is rare and may not exist other
  than as a consequence of pulpitis

Question 24

What is a physiological example of external resorption?

Answer 24

The resorption of deciduous teeth.

Question 25

What are the 7 potential causes of external resorption?

Answer 25

1. Periapical inflammation: causes microscopic resoprtion, unlikely to be large degree
2. Re-implanted tooth: non-vital cementum and dentine frequently resorbed
3. Tumours and cysts: resorption not as likely as it is for tooth to be displaced
4. Pressure from unerupted tooth on the root of adjacent erupted tooth causing root resoprtion (e.g. 3rd molars on 2nd molars)
5. Excessive orthodontic forces
6. Impacted teeth: often begins in the crown, may be caused by loss of reduced enamel epithelium, 80% of cases in maxilla
7. Idiopathic: no obvious cause, more likely in older patients