Tooth Erosion

Introduction
· Tooth erosion is often confused with tooth decay although the causes and symptoms are different.
· Tooth decay occurs when acid is produced by the bacteria in the mouth (plaque), feeding on the carbohydrate in the diet. The effect is also quite localised.
· However, tooth erosion occurs across the whole tooth surface and does not involve bacteria or dietary sugars
· It is the irreversible loss of dental hard tissue due to the chemical process of acid dissolution.


Prevalence
· Tooth erosion was included for the first time in the 1993 National Survey of Child Dental Health conducted in the United Kingdom.
· Results revealed that more than half of 17,061 (5 and 6 year olds) children had some form erosion of the teeth. 25% had dentinal erosion of the primary dentition. Nearly 25% of children in the 11+ age group had erosion, with 2% with dentinal erosion in the mixed dentition.(Betul Kargul & Meltem Bakkal , 2009)


Tooth Erosion as a multifactorial condition
The erosion of teeth is usually the result of interplay between the following factors:
· biological
· chemical
· behavioural
Tooth Erosion - Cariology
Fig 1 Interactions of the different factors for the development of dental erosion (Lussi A, Jaeggi T, 2006)


Biological factors

Saliva (flow, buffer)

· Saliva provides the following protective mechanisms:
  • diluting and clearing out erosive agents
  • neutralising and buffering of acids
  • slowing down the rate of dissolution of enamel through the common ion effect by salivary calcium and phosphate
· Demineralization happens when the tooth enamel begins to lose minerals when exposed to an acidic environment. Saliva however, can neutralise the activity of the acids by restoring the pH back to normal. This is known as the process of remineralization.

· What happens in the mouth is usually a fine balance between demineralization and remineralisation of the enamel. However in tooth erosion, there are factors that can disturb this balance. For example, there can be an increased intensity and frequency of acid attacks that does not give time for the natural restoration of the tooth enamel.
· Additionally, there might be low salivary flow that results in inadequate rinsing and buffering of the acids that demineralise the tooth surface.


Pellicle
· The pellicle is a protein-based layer that is rapidly re-formed on tooth surfaces after its removal by tooth brushing with dentifrice, other prophylaxis or chemical dissolution.
· One of its functions is to protect against erosion by acting as a diffusion barrier or a selectively permeable membrane.
· This inhibits direct contact between acids and the tooth surface, reducing the dissolution rate of hydroxyapatite.


Chemical factors

  • In the event oral fluids are undersaturated with respect to tooth mineral, long term exposure of tooth surfaces to can result in erosion.
  • Under in vitro conditions, teeth demineralise centripetally. This is normally not observed in the mouth.
Tooth Erosion - Cariology

Figure 2: Effect of continuous exposure of a human third molar to 10% citric acid.
The amorphous, centripetal tissue loss is obvious.
(a- unaffected tooth, b- tissue loss after 4h, c- 8h, and d- 12h of immersion time).
( Ganss C , 2008)

In tooth erosion, acids can come from both intrinsic and extrinsic sources:
  • Diet (e.g. carbonated drinks, fruit juice)
  • Gastric acid (e.g. from acid reflux, eating disorder bulimia)
  • Environment (e.g. from chlorinated swimming pools)
· It is noted in recent years that the increased consumption of acidic food and beverages is a significant factor for the development of tooth erosion.


pH and Buffering capacity

  • In previously conducted studies, the initial pH values and buffering capacities of several soft drinks were determined. Carbonated drinks had lower pH than fruit juices. The buffering capacities are in the following order: fruit juices>fruit-based carbonated drinks>non-fruitbased carbonated drinks (Owens, 2007)

Behavioural factors

Acidic drinks and food

  • In the USA, soft drink consumption increased by 300% in 20 years (Cavadini C et. al, 2008) This increase is correlated with the progression of erosion when other risk factors exist (Lussi A & Schaffner M, 2000)
Tooth grinding and brushing
  • Hard tissue loss after erosion and toothbrushing is significantly greater than erosion alone (Rios D et. al., 2006)

  • Erosion usually co-exists with attrition and/or abrasion, but one of these factors may be more important than the other (Sullivan E.O.& Milosevic A. , 2008). Attrition occurs when teeth are eroded by tooth-to-tooth contact for example in teeth grinding. Abrasion is caused by external mechanical factors such as incorrect tooth brushing.
Regurgitation

· The pH of stomach acid is much lower than the critical pH of enamel dissolution;
· Reflux of stomach contents into the oral cavity over a prolonged period of time can cause severe loss of tooth structure.



Signs and symptoms

Early Symptoms

· Discoloration – Teeth can become yellow because dentine is exposed. The more dentin that is exposed, the more yellow the teeth will become.
· Tooth Sensitivity – Protective enamel is worn away, leaving the exposed dentine. Pain is usually felt when one consumes hot, cold or sweet foods and drinks.
· Rounded Teeth – Teeth will appear with a broad rounded concavity.
· Transparent or Sand Blasted Appearance – Teeth may appear sand-blasted or look transparent near the biting edges.

Advanced Symptoms
· Cracking – Small cracks and roughness may appear at biting edges of teeth.
· Cupping - Small dents can start to appear on the biting areas of the teeth. Fillings also might appear to be rising out of the tooth.
· Severe Sensitivity - Since the enamel wears away during tooth erosion, the teeth can become extremely sensitive during the advanced stages of tooth erosion.

Tooth Erosion - Cariology

Figure 3: Early enamel erosion in 36-year-old female patient. Tooth is observed to have a glazed shiny surface.
(Magalhães AC, 2009)

Tooth Erosion - Cariology

Figure 4: (a – c) Advanced stages of erosion of teeth 45 and 46 in three different patient. Dentine is exposed in all three.
(Lussi A & Jaeggi T, 2008)


Prevention and management

There are different reasons for tooth erosion, but the following are some general preventive steps:
· Reduce or eliminate drinking carbonated drinks.
· Drink acidic drinks quickly and use a straw so that liquid is pushed to the back of the mouth.
· After consuming high-acid foods, rinse mouth with water to neutralise the acids.
· Check sugar-free gum to produce more saliva that aid in remineralization.
· Use a soft toothbrush and toothpaste that contains fluoride.





References

Betul Kargul, Meltem Bakkal (2009, August 25). Prevalence, Etiology, Risk Factors, Diagnosis, and Preventive Strategies of Dental Erosion: Literature Review (Part l & Part II). [Electronic version]. Acta Stomatologica Croatia. 2009;43(3):165-187. Retrieved Oct 5, 2009 from http://www.ascro.net/index.php?id=504#c4530

Cavadini C, Siega-Riz AM, Popkin BM.(2000). US adolescent food intake trends from 1965 to 1996. Arch Dis Child; 83: 18-24.

Ganss C. (2008). How valid are current diagnostic criteria for dental erosion? Clin Oral Investig;12 Suppl 1:S41-9.

Lussi A, Jaeggi T. (2006). Chemical factors. Monogr Oral Sci. 2006;20:77-87.

Lussi A, Jaeggi T.(2008). Erosion--diagnosis and risk factors. Clin Oral Investig;12 Suppl 1:S5-13.

Lussi A, Schaffner M. (2000). Progression of and risk factors for dental erosion and wedge-shaped defects over a 6-year period. Caries Res. 2000 Mar-Apr;34(2):182-7.

Magalhães AC, Wiegand A, Rios D, Honório HM, Buzalaf MA. (2009). Insights into preventive measures for dental erosion. J Appl Oral Sci;17(2):75-86

O'Sullivan, E., Milosevic A. (2008). UK National Clinical Guidelines in Paediatric Dentistry: diagnosis, prevention and management of dental erosion. Int J Paediatr Dent. 2008 Nov;18 Suppl 1:29-38.

Owens BM. (2007). The potential effects of pH and buffering capacity on dental erosion. Gen Dent. 2007 Nov-Dec;55(6):527-31.

Rios D, Honório HM, Magalhães AC, Buzalaf MA, Palma-Dibb RG, Machado MA, et al. (2006). Influence of toothbrushing on enamel softening and abrasive wear of eroded bovine enamel: an in situ study. Braz Oral Res. 2006;20(2):148-54.











Links

An Introduction | Tooth Anatomy and Histology | Dental Caries | Dental Caries - An Infectious Disease or a Chronic Disease |

Early Caries and Enamel Changes | Caries Progression and Dentine Changes | Pulpo-dentinal Changes

Root Surface Caries and Changes in the Cementum
| Dental Fluorosis | Erosion of the Teeth | Conclusion


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