UNIDAD FORMATIVA 3
3. Informes y presentaciones comerciales de la información de mercados
Definition
Dental caries is defined as a microbiological disease of the hard structure of teeth, exposed in oral cavity, that results in localized demineralization of the inorganic portion and destruction of the organic substances of the tooth, beginning on the external surface.
Etiology
The etiological agents of dental caries are pathogenic bacterial plaque. There are two basic hypothesis concerning the pathogenicity of plaque.
1. Non-specific plaque hypothesis: According to this hypothesis all plaques are pathogenic because pathogenic bacteria are universally present in plaque. 2. Plaque and caries: The carious lesions are started when specific bacteria in plaque are increased and active pH is decreased. The plaque will become pathogenic when signs of caries develop.
Theories of Etiology of Dental Caries 1. Endogenous theories: • Humoral theory • Vital theory. 2. Exogenous theories: • Chemical theory • Parasitic theory
• Miller’s acidogenic theory • Proteolysis theory
• Proteolysis chelation theory. 3. Other theories:
• Autoimmune theory
• The legend of worm • Sulfatase theory.
Local Factors Affecting the Incidence of Caries (Fig. 29.1) A. Microorganisms: Microorganisms present, on the tooth surface like Streptococcus mutans and Lactobacillus cause dental plaque.
B. Tooth a. Morphological variation b. Composition c. Position C. Environmental factors a. Saliva 1. Composition 2. Quantity 3. pH viscosity
4. Antibacterial factors like enzymes.
b. Diet
1. Physical factors 2. Local factors
a. Carbohydrate content—Presence of refined cariogenic carbohydrate particles on the tooth surface
b. Vitamin content c. Fluoride content d. Fat content D. Time period
GIVE CLINICAL CLASSIFICATION OF DENTAL CARIES?
Dental caries may be classified according to the following:
The surface topography and environmental conditions:
1. Pits and fissures caries (Fig. 29.2):
• Initially, they appears brown or black in color and with a fine explorer it will feel soft and a ‘catch’ is felt.
• The enamel which borders the pits and fissures appears opaque bluish-white.
• If enamel is thin at the base of pits and fissures, it causes early involvement of dentino-enamel junction and caries spreads laterally and involves dentin.
2. Smooth enamel surface caries (Fig. 29.2):
• Occur on gingival third of buccal and lingual surfaces and on proximal surfaces.
• Occur because of lack of plaque control. • Shape is two triangles.
• On proximal surface caries begins below the contact point.
• It appears as a slightly roughened chalky area which gradually becomes excavated.
3. Root surface caries:
• Located on dentin and cementum of root surface. • Rapidly progressive
• Associated with old age
4. Cervical caries – It starts from cervical region of the tooth.
The rapidity of the caries progress, it is classified as follows:
a. Acute dental caries:
• Travels towards the pulp at a very fast speed. • Multiple and light colored
• Rapidly involve pulp. b. Rampant caries:
It is a suddenly appearing, rapidly burrowing type of caries resulting in early pulp involvement, in which more than 10 new lesions appear every year on healthy teeth surfaces which are generally immune to caries.
• It occurs usually in deciduous dentition.
• Usually affects maxillary four incisors, then molars followed by canines
• Due to severe carious process only root stumps remain.
Rampant caries is of following three types: • Nursing bottle rampant caries
• Adolescent rampant caries
• Xerostomia induced rampant caries (radiation rampant caries).
c. Chronic dental caries: • Progresses slowly
• Involves the pulp much later than acute caries • Due to slow progression of caries process there is
sufficient time for sclerosis of dentin and formation of reparative response to the adverse irritation
• There is no or less pain in chronic caries. d. Arrested caries:
• Arrested caries occurs on occlusal and proximal surfaces
• Characterized by a large open cavity which no longer retains food and becomes self-cleansing. • On the proximal surface they occur due to
extraction of adjacent tooth.
• It appears as brown-stained area just below contact point of retained tooth.
• The caries process is arrested due to area of proximal surface becoming self cleansing because of extraction of adjacent teeth.
Fig. 29.2: Diagrammatic representation of pit and
126 Review of Endodontics and Operative Dentistry
Whether caries attacks previously intact surface or margin of restoration, it is classified as follows:
1. Primary caries:
• They are white spot lesions • Reversible
• Can be mineralized
• Describe first attack on the tooth surface
• Shape of lesion depends on location i.e. whether pit and fissure or smooth surface lesion.
2. Secondary or recurrent caries:
• They occurs at the margins of a restoration. • The causes of secondary caries are poor adap-
tability of restorative materials to the cavity walls and leaky margins or inadequate extension of restorative materials to margin of cavity, which favour the retention of food debris and bacteria.
The proximity of caries to pulp:
By relating the caries to their clinical location, GV Black gave a simple cavity classification listed as class I, class II, class III, class IV and class V. An additional class VI was later on added by Simon as modification to Black’s classification.
Class I: Pit and fissure cavities occur in the occlusal
surfaces of premolars and molars, the occlusal two-third of buccal and lingual surface of molars, lingual surface of incisors.
Class II: Cavities in the proximal surface of premolars
and molars.
Class III: Cavities in the proximal surface of anterior teeth
and not involving the incisal angles.
Class IV: Cavities in the proximal surface of anterior teeth
also involving the incisal angle.
Class V: Gingival cavities on gingival third (not pit and
fissure cavities) on facial and lingual or palatal surfaces of all teeth.
Class VI: Cavities on incisal edges of anterior and cusp
tips of posterior teeth without involving any other surface.
WHAT IS CARIES OF ENAMEL?
Caries of enamel starts by deposition of microbial plaque on enamel surface. Two types smooth surface caries, and pit and fissure caries.
Smooth Surface Caries
• Earliest manifestation of incipient caries is like a smooth chalky white area.
• Carious lesions have cone or triangular shape, in which apex is toward the pulp and base toward the outer surface of tooth.
• Smooth surface caries occurs on gingival third of buccal and lingual surfaces and on proximal surfaces. • On proximal surface caries begins below the contact
point.
• Caries in the cervical area is in the form of crescent shaped cavities.
Pit and Fissure Caries
• Shape of pits and fissures contributes to their high susceptibility to caries because in these structures bacteria and food debris are packed.
• The microorganisms ferment this food and acid is produced and caries is initiated.
• Initially they appear brown or black in color, enamel which borders the pits and fissures appears opaque bluish-white.
• Early involvement of dentino-enamel junction and dentin because of thin enamel at pits and fissures causes undermining of enamel. This undermined enamel is sometimes fractured by masticatory forces. • When undermined enamel fractures, it causes
cavitation and caries.
Zone in Caries Lesions
These zones are beginning on the dentinal side of the lesion.
Zone 1: Translucent Zone
• It represents the advancing front of the enamel lesion. • Not always present.
• This is ten times more porous than sound enamel. Zone 2: Dark Zone
• Lies adjacent and superficial to the translucent zone. • Called as dark zone because it does not transmit
polarized light
• Also known as positive zone, because it is usually present.
• Formed by demineralization because deminerali- zation and remineralization both occur in this zone. Zone 3: Body of Lesion
• Largest portion.
• Stria of Retzius are well marked indicating more demineralization and thus more porous.
• Varying from 5 percent at the periphery to 25 percent at the center.
Zone 4: Surface Zone
• Least affected by caries because it is hypermineralized and has more fluoride.
• More resistant to caries. • Less than 5 percent porous.
WHAT IS CARIES OF DENTIN?
Caries in dentin spreads more rapidly in comparison to enamel because dentin provides much less resistance to acid attack.
Changes in Early Dentinal Caries
• Slowly progressing caries causes dentinal sclerosis. • This alteration in dentin is a reaction of vital dentinal
tubules and vital pulp to prevent further penetration by microorganisms.
• In slowly advancing caries, formation of sclerotic dentin is more.
• When dentinal tubules are completely occluded by the mineral precipitate, tooth gives transparent appearance, this is termed as transparent dentin. • In the earliest stages of caries when only a few tubules
are involved, microorganisms found in these tubules are termed as “pioneer bacteria”.
Changes in Advanced Dentinal Caries
• The diameter of dentinal tubules increases due to packing of microorganisms. Due to the focal coalescence and breakdown of a few dentinal tubules, tiny “liquefaction foci” are formed.
• These “foci” are ovoid areas of destruction, which tend to increase in size by expansion producing compression and distortion of adjacent dentinal tubules.
Zones of Dentinal Caries
• Five different zones in dentinal caries.
• Are clearly distinguished in slowly progressing caries and less distinguished in rapidly progressing caries. • Zones begin from the pulpal side.
Zone 1: Normal Dentin
• There is fatty degeneration of Tomes fibers.
• Dentin is normal and produces sharp pain on stimulation.
Zone 2: Subtransparent Dentin
• Intertubular dentin is demineralized. • In this zone dentinal sclerosis takes place.
• Damage to the odontoblastic zone process is evident. • No bacteria in this zone.
• This zone is capable of remineralization. Zone 3: Zone of Dentinal Sclerosis
(Transparent Dentin)
• Further demineralization of intertubular dentin lead to softer dentin.
• Pain on stimulation. • No bacteria present.
• Zone has the capacity of self-repair by reminerali- zation of the intertubular dentin.
Zone 4: Turbid Dentin
• Characterized by widening and distortion of the dentinal tubules which are filled with bacteria. • Dentin is not self-repairable.
• There is less mineral content and irreversibly denatured collagen. So during cavity preparation for restoration this zone should be removed.
Zone 5: Decomposed Dentin
• Outermost zone which consists of decomposed dentin filled with bacteria.
• Must be removed prior to restoration of carious tooth.
DIFFERENCE BETWEEN INFECTED AND AFFECTED DENTINE
Infected Dentine
128 Review of Endodontics and Operative Dentistry
• Demineralized dentine. • Can’t be remineralized. • Lacks sensation.
• In this intertubular layer is demineralized with irregularly scattered crystals.
• Collagen fibers are broken down, appear as only indistinct cross bands.
• It can be stained with:
– 0.2 percent propylene glycol – 10 percent acid red solution – 0.5 percent basic fuschin.
Affected Dentine
• It is a deeper layer.
• Intermediate demineralized dentine. • Can be remineralized.
• It is sensitive.
• In this intertubular layer is only partly demineralized. • Distinct cross bands are present.
• It can not be stained with any solution.
WHAT ARE DIFFERENT METHODS OF CARIES DIAGNOSIS?
Following methods are used for the diagnosis of caries: • Visual inspection methods: For inspections following
instruments, devices and techniques are used. – Magnifying mouth mirror.
– Magnifying lens.
• Special illumination techniques:
– Ultraviolet Illumination: Ultraviolet (UV) light increases optical contrast between carious area and the surrounding healthy tissue.
Advantage
It is more sensitive and gives more reliable results than visual and tactile methods.
Disadvantage
Carious lesion and developmental defect cannot be distinguished by UV illumination.
Fiberoptic Transillumination (FOTI)
Light is delivered via fiberoptics from a light source on the surface of the tooth. The light travels from the fiber illumination across tooth tissue to non-illuminated
surface. This results in image formation which is used for diagnosis.
Advantages
• Lesions which cannot be diagnosed radiographically can be diagnosed
• No radiation hazard • Comfortable to patient Disadvantage
FOTI is not possible in all locations of carious lesions
Wavelength Dependent FOTI
Advantages
• It gives quantitative information about depth of the lesion
• There is no radiation hazard. Disadvantage
Same as with FOTI.
Digital Imaging FOTI
It works on basis of the principle that the images of teeth obtained through visible light fiberoptic trans- illumination (FOTI) are acquired with digital CCD camera and sent to a computer for analysis with dedicated algorithms.
Detection of Carious Enamel by Dyes
• Calcein • Procion • Brilliant blue
Endoscope Technique
Endoscope technique is based on observing the fluorescence which takes place when the tooth is illuminated with blue light in the wavelength range of 400 to 500 nm. Sound enamel and carious enamel produce different fluorescence.
Tactile Method
Here smoothness, roughness and softness is determined by sharp explorers of various shapes.
Radiographic Methods
1. Intraoral periapical radiographs.
2. Bitewing radiographs: They provide good view of the following:
a. Interproximal caries b. Recurrent caries
c. Recurrent or secondary caries below proximal restoration.
3. Xeroradiography: In this the latent images are recorded on an aluminum plate coated with selenium particles. The latent images are developed in the positive images.
4. Digital imaging.
Direct digital imaging: In this radiation rays are directly
collected by digital image receptor.
Indirect digital imaging: In this video camera forms digital
image of radiographs. 5. Subtraction radiography:
By this technique structured radiographic noise is reduced in order to increase the detectability of changes in the radiographic pattern.
Electrical Conductance Measurement Method
Due to high mineralization sound enamel is very bad conductor. Electric conductivity is directly proportional to the amount of demineralization present.
Lasers
Following types of lasers are used for diagnosis of caries. Diagnodent
Diagnodent is a diode-laser caries detector. It can be used to determine the soundness of tooth structure on occlusal surfaces.
Quantitative Laser Fluorescence (QLF)
Here argon laser is used to monitor caries lesions Optical Coherence Tomography (OCT)
In OCT cross sectional images of biological tissues are created using differences in the reflection of light. DNA Chip Technology (DNACT)
DNACT is a new system which combines the use of computer and molecular biology technologies.
Caries Activity Tests (Table 29.1)
Caries activity tests are important in individual persons to help the practitioner arrive at decisions in relation to preventing and controlling measures. The timing of recall appointments, indication of type of restorative pro- cedures and materials, and assessing the prognosis.
Table 29.1: Caries activity tests and their principles
S. No Test Principles and Results
1. Buffering capacity To estimate buffering capacity, a saliva
sample is used
2. Fosdick Capacity of saliva sample to dissolve
powdered enamel is measured
3. Dewar
4. Lactobacillus count By counting colonies on a culture media
plate the number of bacteria in saliva is estimated
5. Snyder In culture media the rapidity of acid
formation from a saliva sample is measured
6. Mutans streptococci By use of selective culture media the
screening number of colony forming bacteria are
estimated
7. Reductase From a saliva sample, activity of reductase
enzyme to change the color is measured sample in culture media is measured
130 Review of Endodontics and Operative Dentistry
WHAT ARE DIFFERENT WAYS FOR CARIES PREVENTION?
Caries can be prevented by three methods.
Chemical Method
• Fluoride: Fluoride alters the tooth surface or/and tooth structure to increase resistance to deminerali- zation and prevent dental caries. Fluorides are used in the following forms:
a. Fluoridation of water supplies b. Topical application of fluoride
i. Sodium fluoride (NaF) ii. Stannous fluoride (SnF2)
iii. Acidulated fluorido-phosphate iv. Prophylactic paste
v. Fluoride dentifrices
vi. Fluoride mouthwashes or rinses. • Chlorhexidine
• Zinc chloride • Caries vaccine • Vitamin K.
Dietary Method
Caries can be prevented by the restriction of intake of refined carbohydrate. Sucrose is most cariogenic carbohydrate, hence its use in food should be restricted.
Mechanical Methods
• Tooth brushing • Dental floss • Mouth rinsing
• Pit and fissure sealants.
HOW IS PULP PROTECTION DONE IN MODERATE AND DEEP CARIOUS LESIONS? Pulp Protection in Moderate Carious Lesions
• Moderate carious lesion is one in which the caries penetrates the enamel and may involve one half of the dentin, but not to the extent of endangering the pulp.
• After cavity preparation, the liner is applied to cover the axial and/or pulpal wall.
• Then, base is placed over the liner. • After this permanent restoration is done.
Pulp Protection in Deep Carious Lesions
In deep cavity, the caries can reach upto the pulp. If hard dentin is present, protective cement base and permanent restoration is done as in moderate lesion.
Indirect Pulp Capping
Here all the carious tissue is removed except the soft undiscolored carious dentin which is adjacent to the pulp. Indications
• Deep carious lesion near the pulp tissue but not involving it.
• No mobility of tooth.
• No history of spontaneous toothache. • No tenderness to percussion.
• No radiographic evidence of pulp pathology. • No root resorption or radicular disease should be
present radiographically. Contraindications
• Presence of pulp exposure.
• Radiographic evidence of pulp pathology. • History of spontaneous toothache.
• Tooth sensitive to percussion. • Mobility present.
• Root resorption or radicular disease is present radiographically.
Materials Used • Zinc oxide eugenol. • Calcium hydroxide. Technique
• Cavity is cleaned, dried and covered by calcium hydroxide and temporary restoration.
• After 2 to 3 months, the cement is removed and the cavity is inspected.
• If due to remineralization and/or formation of secondary dentin the soft dentin has become hard, then remove any residual soft debris.
• Finally give protective cement base and place the permanent restorative material.
Direct Pulp Capping
The purpose of direct pulp capping is to preserve the vitality of the pulp by placing the medicament over the
exposure site, so as to provide an environment for the healing of the pulp.
Indications
• Small mechanical exposure of pulp during – Cavity preparation
– Traumatic injury
• No or minimal bleeding at the exposure site. Contraindications
• Wide pulp exposure.
• Radiographic evidence of pulp pathology. • History of spontaneous pain.
• Presence of bleeding at exposure site. Technique
• When vital and healthy pulp is exposed, fresh bleeding of bright red blood takes place.
• After the bleeding at the exposure site is stopped, clean and dry the area.
• Over the exposure site, calcium hydroxide is placed, which is sealed by temporary cement.
• After 2 to 3 months, the cement is removed.
• If secondary dentin formation takes place, tooth is restored permanently.
MATERIALS USED FOR PULP PROTECTION
Various materials are used to: • Insulate the pulp
• Protect the pulp
• Act as barriers to microleakage
• Prevent bacteria and toxins from affecting the pulp.
The Materials Used for Pulp Protection
• Cavity Varnish • Cavity Liners
• Calcium Hydroxide and Mineral Trioxide Aggregate (MTA)
• Zinc Oxide-Eugenol • Zinc Phosphate Cement • Polycarboxylate Cement • Glass Ionomer Cement.