Preventive dentistry prevention of dental caries Lec:2
Definition
Dental caries: It is a multifactorial disease mainly bacterial etiology,
characterized by demineralization of the inorganic portion and destruction of the
organic substance of the tooth. The carious process affects the mineralized tissues of
teeth (enamel, dentine, and cementum) and caused by the action of microorganisms
on fermentable carbohydrates in the diet. The disease is often described to be
progressive and if not treated may expand in size and progress to the pulp leading
pulp inflammation, thus pain and discomfort and the end results will be loss of
vitality then loss of tooth.
Etiology of Dental Caries
Tooth decay initiated by the interaction between multi etiological factors. The
main factors are the host like teeth and saliva; the microorganism like bacteria and
biofilm; the substrate like dietary sugar; in addition to the time.
1- Host:
Teeth vary in their susceptibility from one surface to another and from one
subject to another. There are several factors relating to the tooth susceptibility of
dental caries involves susceptible tooth and saliva, in addition to the subject him/
her self.
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Morphology of teeth: the susceptible sites on the tooth that favors plaque retention
are more prone to decay such:
1- Enamel pits and fissures.
2- Approximal enamel smooth surfaces.
3- Cervical margin of teeth.
4- Exposed root surfaces because of gingival recession.
5- Deficient or over hang restoration (recurrent caries).
6- Tooth surfaces adjacent to denture and bridges.
Positions of teeth: posterior teeth are labial to be affected by caries compared to
anterior.
Composition of teeth: the teeth are composed of inorganic elements (96% in
enamel, 70% in dentin), organic elements and water. The composition of teeth is
affected by environmental factors (water, diet and nutrition).
Inorganic components: involve a major elements as calcium, phosphate, and
hydroxyl group that constituents hydroxy apatite crystals Ca10 (PO4)6 (OH)2 and a
minor elements in teeth as Zinc, copper, magnesium, fluoride etc. These minor
elements may incorporate the enamel crystal in substitutions with one if its major
elements for example the substitution of OH group by Fluoride ions Ca10 (PO4)6 F2.
This incorporation may take place either in the pre eruptive stage including all layers
of enamel and dentin, or in the post eruptive stage involving the outer enamel surface
only. Some of these elements when incorporated may increase the resistance of teeth
to dental caries such fluoride ions, tin ions, zinc, strontium, and molybdenum. While
other elements, may increase the susceptibility to dental caries like magnesium.
Saliva:
Saliva secretion plays an important role in preventing plaque accumulation
and maintaining teeth integrity in the oral cavity, human saliva contains a wide range
of mucins, glycoproteins, enzymes, salts, immunoglobulins, and antimicrobial
peptides that contribute to biofilm stability and control. Impaired saliva functions
due to of aging, systemic medical conditions, chemo- and radiotherapy are
commonly associated with biofilm formation and overgrowth of candida species.
Saliva affects the integrity of teeth by the composition (buffer system, calcium and
phosphate ions); the rate of salivary secretion affect the cleansing action of saliva
(oral clearance); it can affect to a large degree the cariogenic bacteria and number of
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oral microorganisms in the mouth by oral immune system (specific and non-
specific).
Subject: The behavior, attitude and dental knowledge affect the caries etiology.
These can influence the oral hygiene of the person as well as his dietary habits.
2- Biofilm: Dental biofilm accumulation is an essential step for caries formation,
the quantity and quality of plaque are greatly influence the caries etiology.
The cariogenic bacteria such as mutans streptococci, lactobacilli and others
has acid tolerating properties, ability to adhere on the tooth surface, and
dietary sugars are readily metabolized by biofilm microorganisms to produce
organic acids (mainly lactic acid), which lowers the pH of the biofilm. Thus
demineralization of tooth surfaces occur.
3- Diet: Some authors have emphasized the importance of the dental biofilm and
others dietary sugars, both are essential primary etiological factors driving
caries expression and one cannot cause caries in the absence of the other.
Sweet diet consumption especially between meals may lead to continuous
sugar fermentation and acid production, which lead to drop in pH and not
allowing the enough (time) for the normal pH to return to by the buffering
action and clearance of saliva. Frequent and prolonged lowering of biofilm
pH favours the growth of the more acid-tolerant (aciduric) bacteria, such as S.
mutans and lactobacilli which are also highly acidogenic. Thus
demineralization of teeth occur.
Caries Process
Our basic understanding of the caries process dates back over 125 years to
W.D. Miller’s Chemoparasitic Theory (1890) and to a large extent we are still
managing dental caries using turn of the last century surgical approaches intended
to remove the demineralized tissue and halt the disease process. Today dental caries
is understood as a dynamic process involving cycles of mineral loss
(demineralization) and mineral gain (remineralization). Several protective and
pathological factors are involved that can shift the balance towards health or disease.
The tooth surface is in a healthy state of dynamic equilibrium with the local oral
environment when demineralization and remineralization are in balance or favour
remineralization. This modern understanding of the caries process supports the shift
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in caries management to detecting caries at an early (non-cavitated) stage and risk
assessment to determine appropriate preventive intervention and recall frequency.
Caries Risk Assessment
Caries risk assessment can play several important roles in the clinical
management of dental caries:
1) Helping dental professionals determine if additional diagnostic procedures are
required.
2) Identifying patients who need additional caries control measures.
3) Assessing the effectiveness of interventions to prevent caries.
4) Guiding clinicians in making treatment plan decisions and in scheduling the
frequency of recall appointments.
A number of different caries risk assessment systems involving paper forms
or computer-based programs have been developed to help dentists assess caries risk
using many of the factors covered above, it is important to note that caries risk-
assessment systems need to be targeted at specific patient age groups as risk factors
vary with age. As a general rule, patients in a ‘low’ risk category will have had no
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incipient or cavitated primary or secondary carious lesions during the last two years
and no change in the risk factors that may increase caries. Patients in a ‘moderate’
risk will have had one or two incipient or cavitated primary or secondary carious
lesions in the last two years. Patients at ‘high’ risk will have had three or more
incipient or cavitated primary or secondary carious lesions in the last two years.
Prevention of Dental Caries
Primary Prevention Strategies
The expression of caries can be mainly attributed to an individual’s behaviours
involving frequent ingestion of fermentable carbohydrates (sugars) and inadequate
oral hygiene. Therefore, primary prevention strategies need to be mostly directed at
modifying or eliminating aetiological factors driving the caries process and by
increasing protective factors to arrest caries from progressing that are include:
1) Educating the public and patients on good oral health behaviours and thus
empowering them to be responsible for their own health.
2) Biofilm formation control either mechanically by tooth brushing twice daily
with toothpaste and interdental flossing or chemically by using antimicrobial
agent such as chlorhexidine mouth wash.
3) Patients advised to limit the frequency of sugar exposures and to substitute
sugar containing foods and beverages with alternatives that are less
cariogenic.
4) Use sugar-free chewing gum for 10-20 minutes after meals is recommended
to stimulate salivary flow, clearance and buffering action.
5) Community water fluoridation or use of dietary fluoride supplements such as
drops and tablets.
6) For individuals at higher risk of developing dental caries, fluoride mouthrinses
are recommended in addition to fluoride toothpaste.
7) Professional application of topical fluoride treatments in higher risk
individuals like fluoride gels or fluoride varnishes two to four times per year.
8) Use of dental sealants for preventing the initiation (primary prevention) or
progression (secondary prevention) of dental caries on occlusal surfaces of
permanent molars.
9) Regular 6-month recall visits and dental check-up provide the opportunity for
caries risk assessment and professional interventions.
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Secondary Prevention Strategies
Secondary prevention comes into play when caries has progressed to the stage
that it is clinically detectable (non-cavitated lesion or white spot), but not so far that
the lesion has cavitated requiring operative intervention (tertiary prevention). The
goal is to reduce the impact of caries as early as possible by preventing further tooth
destruction (demineralization) and possibly reversing the caries process in favour of
remineralization. Secondary prevention requires oral health professionals to
1) Accurately detect and assess the early stages of the disease (non-cavitated
lesions).
2) Use of non-invasive intervention as professionally applied 5% NaF varnish
can remineralise early enamel caries and 38% silver diamine fluoride.
3) Using non-fluoride agents like xylitol, chlorhexidine, and CPP-ACP alone or
in combination with fluoride.
4) Use of therapeutic dental sealants.
5) Use of micro-invasive strategies like resin Infiltration concept (Icon) effective
method to arrest the progression of non-cavitated caries proximal lesions.
6) Use of minimal-invasive techniques has been advocated to preserve tooth
structure like prevention dentistry restoration.
Preventive Dentistry Restoration
This include both concept of prophylactic odontomy and extension for
prevention that requires minimal cutting of tooth structure at the carious site and
maximum tooth conservation. It is indicated in cases were the caries has reached the
dentin, preventive restoration considered a viable option compared to more
destructive conventional approach. The main difficulty in determining the optimal
form of early caries management is the diagnosis of the lesion, which can be done
by use of laser fluorescent for diagnostic accuracy on the presence and depth of the
caries in occlusal pits and grooves.
