Dental Caries Pathology, Diagnosis and Prevention
Dental Caries Pathology, Diagnosis and Prevention
Dental Caries Pathology, Diagnosis and Prevention
Demineralization: loss of minerals from the tooth when the pH is dropping due to the effect of bacteria in the biofilm which are always metabolically active, causing minute fluctuations in pH. Remineralization: is the process of gaining minerals when the pH is increasing. If the biofilm is partially or totally removed mineral loss may be stopped or even reversed towards mineral gain.
Demineralization
Remineralization
Caries: both the carious process that occurs in the biofilm at the tooth or cavity surface and the carious lesion that forms on the tooth tissue. Carious lesion is the consequence of the carious process.
Dental caries
and fissures on occlusal surfaces of molar and premolar teeth, buccal pits of molars and palatal pits of maxillary incisors.
3. The enamel at the cervical margin of the tooth at the gingival margin. In patients with gingival recession, the area of plaque stagnation is on the exposed root surface.
4. The margins of restorations, particularly where there is a wide gap between the restoration and the tooth or those where the restoration overhangs the margin of the cavity.
Classification of Caries
Acc. to location
Pit/Fissure caries
- Smooth surface caries - Root caries Acc. to origin - Primary - Secondary/Recurrent Acc. to tissues involved - Enamel caries - Dentinal caries - Cemental caries
Acc. to rapidity of the process -Acute/ Progressive Rampant caries Radiation caries -Chronic Arrested caries Acc. to nature of progress - Forward caries - Backward caries Acc. to age - Nursing caries - Senile caries G. V. Black Classification
Dental caries
Crown caries
Root caries
Occlusal caries
Root caries
arrested
acute
Senile Caries: Aging process. Exposed root surfaces. Partial denture clasps.
Rampant caries
A sudden rapid destruction of many teeth, widespread, rapidly burrowing type of caries resulting in early involvement of the pulp and affecting those teeth usually regarded as immune to ordinary decay. More than 10 lesions per year, it can be seen in the following: Primary dentition of infants who continually suck a bottle or comforter containing sugar. Permanent dentition of teenagers and is usually due to frequent cariogenic snacks and sweet drinks between meals. Where there is a sudden marked reduction in salivary flow (xerostomia).
Arrested caries
A carious lesions which do not progress. It is seen when the oral environment has changed from conditions predisposing to caries to conditions that tend to slow the lesion down. Operative treatment is clearly not necessary.
Longitudinal ground section through a carious lesion on a smooth surface examined in water with polarized light. The lesion is cone shaped. Note the relatively intact surface zone (SZ).
Sometimes the lesion is shiny and this would indicate that good plaque control has been re-established and the outer demineralized enamel has been worn away. This lesion is arrested and sometimes it may appear brown due to exogenous stains absorbed by this porous region.
Then in active lesion: Direct dissolution of the outer enamel surface. Physical defect in the surface (cavitation) will take place.
Plaque formation continues within the cavity and this may not be accessible to cleaning aids. For this reason a cavitated lesion is more likely to progress, although it can still become arrested if the patient is able to clean.
Fissures and pits: The lesion forms at the entrance to the fissure (noncleansabl area), and the erupting tooth is particularly susceptible to plaque stagnation because;
The histological features of fissure caries are similar to those already described for smooth surfaces. The lesion forms around the fissure walls and gives the appearance in section of two small smooth surface lesions. The lesions again follow the direction of the enamel prisms and this anatomy gives the lesion the shape of a cone with its base at the DEJ.
A molar tooth with a white spot lesion formed in an area of plaque stagnation at the fissure entrance.
A hemisection of this tooth showing a larger lesion than would be expected from examination of the outer enamel surface.
A hemisection of this tooth showing the cavity and lateral spread of the lesion at the DEJ. There is extensive demineralization of the dentine.
Caries of peripheral dentine will result in pulpal inflammation and chronic inflammatory cells (macrophages, lymphocytes, and plasma cells) will infiltrate the pulp near the odontoblast layer. Initial enamel caries Indeed, may show this chronic inflammatory reaction which is mainly due to the movement of bacterial toxins through the dentinal tubules.
After exposure; bacteria may enter the pulp. Polymorphonuclear leucocytes may now predominate, and acute inflammation can supervene and spread throughout the pulp, resulting in pulpal necrosis. Then, inflammation may move apically until the entire pulp is necrotic. This is followed either by spread of toxins into the periapical tissues at the root apex, producing the chronic inflammatory response of chronic apical periodontitis, or, if organisms pass into the periapical tissues, an acute apical abscess develops.
demineralization of dentine
destruction of the organic matrix damage and death of odontoblasts.
These changes begin before cavitation of the enamel occurs and while the microorganisms are still confined to the tooth surface.
The rate of caries progress is highly variable and provided the biofilm is removed from the cavity surface the progress of the disease can be arrested.
Clinically; in actively progressing lesions, the dentine is soft and wet, and, because of the speed at which some lesions develop, the defence reactions may not have time to be effective.
in arrested or slowly progressing lesions, the dentine, has a hard, leathery, or dry consistency. The defence reactions are well marked and the carious lesion accumulates minerals from the oral and from pulpal blood flow.
Root caries
Exposed root surfaces occur following gingival recession are susceptible to root caries and to mechanical wear and chemical damage more than enamel. Why? because the cementum on the root surface is softer than enamel and dentin Histologically, demineralization appears to take place beneath a well-mineralized surface layer. Deep to the lesion there are often areas of tubular sclerosis and reactionary dentine.
carious lesions can be converted into arrested lesions by regular tooth brushing with a fluoridecontaining dentifrice
Secondary or recurrent caries: is the same as primary caries except that it is located at the margin of a restoration. it is most often localized gingivally where plaque is most likely to stagnate. It can be arrested by regular disturbance of the biofilm with a fluoride-containing dentifrice. Residual caries: The parts of the carious lesion that remain after cavity preparation
Clean teeth
A three-in-one syringe so that teeth can be viewed both wet and dry.
A smooth surface lesion before and after probing. Note the damage that can be caused by a sharp probe.
4. Cavitated lesions may present as microcavities which are easily missed on visual examination but are usually visible in dentine on a bitewing radiograph
It is not possible to judge the activity of a lesion from a single bitewing radiograph. also not possible to know whether a lesion is cavitated. A proximal lesion on the root surface may be diagnosed visually if the gingival health is good. It is also is visible on a bitewing radiograph.
The radiographs record the progress of proximal caries over a period of 18 months
Suggested ranking for radiographic diagnosis of dental caries (early proximal lesions) (Axelson)
After 5 days the separator is removed and now a probe can be used gently to feel whether a cavity is present.
The operating light can help in diagnosis of proximal caries. It is reflected through the contact point with the dental mirror, and a carious lesion appears as a dark shadow following the outline of the decay.
Fibre-optic: a stronger lights, with the beam of 0.5 mm diameter, have been used. The light should be used with dry teeth. The advantages; can detect enamel crazing, cracks and caries
Inactive lesions may be further from the gingival margin, white or brown in colour with a shiny surface. Arrested lesions are hard and shiny, plaque-free, and some distance from the gingival margin.
5. Saliva; Where the dentist suspects from clinical examination that the mouth is dry, or where it is difficult to explain a high caries activity, salivary flow should be measured chairside. The stimulated salivary flow rate can then be expressed in millilitres (ml) per minute. The normal stimulated secretion rate in adults is 12 ml per minute.
Caries prevention
The relevance of the diagnostic information to the management of caries There are three approaches to the management of active caries:
Attempt to arrest the disease by preventive, nonoperative treatment Remove and replace the carious tissues (operative dentistry) and prevent recurrence by preventive, nonoperative treatment Extract the tooth.
Caries prevention
1
Reduce the pathogenic potential of dental plaque
2
Increase the resistance of tooth structure to caries attack
3
Augment salivary factors
Mechanical plaque control: Motivation about the correct way of tooth brushing
With children, pay particular attention to the occlusal surface of erupting teeth. Tooth brush should be kept at right angle to the occlusal surface When a proximal lesion in the outer enamel exist, the patient should be shown how to use dental floss. Root surface lesions are as the same as coronal lesions to control by mechanical plaque control. Pay particular attention to the proximal surfaces of teeth next to a denture.
Bactericide
Mode of Action
Crystallize
Remineralize
Pickards Manual of Operative Dentistry, 2003. Eighth edition. Edwina A. M. Kidd, et al. Strudevants. Art and science of operative dentistry. Fifth edition. 2006 Fundamentals of operative dentistry. A contemporary approach. Third edition. 2006.