Introduction to our project

Introduction

Dental Caries

The seemingly simple term 'dental caries' is being defined in this section, covering the entire scope of dental caries and the direct and indirect factors influencing its formation. It is important to note that this multifactorial disease is not solely confined to the scientific factors of its development, but is greatly influenced by other social and personal factors. Nevertheless, this project will focus on the scientific processes occuring on the tooth during the initiation and progression of dental caries.

Caries - a chronic or infectious disease

This section explores the possibility of dental caries being classified under the term ‘infectious disease’ and/or the term ‘chronic disease’. Firstly, the definitions of the aforementioned classifications of disease are further elucidated before comparisons are being made. We then continue by perusing through the various reasons why dental caries may or may not be classified as either infectious or chronic by studying various experiments, tests and theories on the topic at hand. And at the end of this section a conclusion is drawn up after a brief discussion on the complexity of the disease and whether dental caries should or should not be classified into either category of diseases.

Early caries and enamel changes

This part of the project focuses on early caries and enamel changes. The earliest form of caries is in the form of white-spot lesions (non-cavitated), which is caused by the metabolism of carbohydrates to produce acid by bacteria in the mouth. The acid seeps into the enamel and dentin, causing breakdown of the enamel’s hydroxyapatite structures, of which this process is known as demineralisation. As demineralisation proceeds further, cavities form. The most common form of caries is occlusal caries, due to the pit and fissures on the occlusal surfaces of teeth that allow easy accumulation of bacterial and plaque. Remineralisation comes in when properties in the saliva neutralises the acid produced by the plaque microbes to restore the hydroxyapatite structures in the tooth. The balance between demineralisation and remineralisation thus accounts for the progress of dental caries.

Caries progression and dentine changes

Caries progression is a repeat of many cycles of demineralisation and remineralisation in favour of demineralisation. However, the rate of progress is heavily dependant on the imbalance of the 2 counteracting forces that degrade and maintain/restore the tooth. Therefore it can be a slowly occuring process or very fast process, depending on which of the the 2 forces is stronger and the magnitude by which it is stronger. Besides affecting the enamel structure, caries can have profound effect on the underlying dentine. Dentine unlike enamel, can react to dentine caries due to the presence of odontoblast. As a result the structure of the dentine continually undergoes not only due to the progression of the caries but also as a result of reactionary mechanisms that attempt to slow down and restore the tooth structure. Which of the 2 forces (caries vs the reactionary defence mechanism) is stronger will ultimately determine the rate of progression of caries in the dentine.

Pulpo-dentinal changes due to caries

During carious attack, demineralization of tooth structure elicits a response from the pulp chamber. Odontoblasts at the pulpo-dentinal junction first sense the demineralization due to movements of dentinal fluid. A mechanical signal is sent from the odontoblasts to the nerves in the pulp, initiating immune response by T cells and macrophages in the pulp. Odontoblasts that survive carious attack initiate the formation of sclerotic dentine (the innate protective mechanism) so as to block further carious attack. Varying extent of injury to the tooth and pulp results in different outcomes that requires different types of therapy. In severe cases, pulpitis may ensue.

Root surface caries and changes in the cementum

Root caries arises due to exposure of the gingival margin of the tooth, often due to bad oral practices or recession of the gingival margin in old age. Cementum - the structure that surrounds the root of the tooth - is soft and easily eroded away, exposing the dentin inside to acid attack and demineralization. Root caries can be active or arrested, the former requiring regular removal of caries so as to arrest the caries. Dentin response due to root caries is similar to that in coronal caries.

Dental fluorosis

Dental fluorosis is a disorder of the teeth, where the tooth may appear discoloured or stained, with pits and cracks on the surface. It has long been associated with excessive fluoride intake, and frequently downplayed as a mere superficial, cosmetic problem. In this section we aim to dispel the myths and assumptions about dental fluorosis, explain how and why it happens, and raise questions about the next step in dealing with dental fluorosis.


Tooth erosion

Tooth erosion results from the chemical process of acid dissolution that leads to the loss of dental hard tissue. There are multiple factors that could cause tooth erosion, and these are broadly classified under biological (eg. Saliva flow), chemical (eg. pH of drinks) and behavioural (eg. Tooth brushing habits). Common symptoms of tooth erosion such as rounded teeth can be prevented against by taking precautionary measures.




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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