Cariology Midterm Part 2

Second stage of caries in Pits & Fissures

Soon after the initial enamel lesion occurs, a reaction can be seen in the dentin and pulp. Forceful probing of the lesion at this stage can result in damage to the weakened porous enamel and accelerate the progression of the lesion. Clinical detection at this stage should be based on observation of discoloration and opacification of the enamel adjacent to the fissure. These changes can be observed by careful cleaning and drying of the fissure.

Dietary Analysis

Sugar intake in the form of fermentable carbohydrates and increased frequency of intake are conditions that increase risk for caries. *The use of candies and lozenges frequently during the day or night increases the risk. *Acidic beverages, including sport drinks, fruit juices, and soft drinks, all contribute to increasing risk by providing energy to the acidogenic and aciduric bacteria and by influencing the pH of the biofilm to support cariogenic bacteria. *Frequency of snacking and the frequency of consuming these foods and beverages all support an increase in biologic caries risk factors by modifying the biofilm to support a lower pH environment.

Enamel Caries Histology

Surface (a) appears to be intact. Body of lesion (b) shows enhancement of striae of Retzius. Dark zone (c) surrounds body of lesion, whereas translucent zone (d) is evident over entire advancing front of lesion.

What should you follow once a patient has been determined to be high risk for ROOT caries?

an aggressive preventive protocol. This protocol is based upon four primary strategies for the prevention of root caries.

Social, Economic and Education Status

are not directly involved in the disease process but are important because they affect the expression and management of the caries disease. The socioeconomic status and educational status of the patient have implications on the necessary compliance and behavioral changes that can decrease risk for caries in patients. These are predictive at the population level but are generally inaccurate at the individual level.

Why are resin-modified glass ionomer materials preferred for definitive restorations?

because they bond effectively to both enamel and dentin and they act as reservoirs for fluoride which can be re-released into the oral

Presence of trace amounts of fluoride ions during remineralization greatly enhance?

greatly enhances the precipitation of calcium and phosphate, resulting in the remineralized enamel becoming more resistant to subsequent caries attack because of the incorporation of more acid-resistant fluorapatite.

Saliva's role in protection against caries

inhibition of bacteria, diluting and eliminating bacteria and their substrates, buffering bacterial acids, and offering a reparative environment with necessary calcium and phosphate minerals after bacteria-induced demineralization.

Root Surface Caries

is rougher than enamel • Readily allows cariogenic biofilm formation in the absence of good oral hygiene • Cementum covering the root surface is extremely thin and provides little resistance to caries attack. • Critical pH for dentin is higher than for enamel, so demineralization is likely to start even before the pH reaches the critical level for enamel (pH = 5.5)

What kind of bacteria is found in carious pits and fissures?

large numbers of MS

What of remineralized lesions look like?

observed clinically as intact, but discolored, usually brown or black, spots. The change in color is presumably caused by trapped organic debris and metallic ions within the enamel. These discolored, remineralized, arrested caries areas are intact and are more resistant to subsequent caries attack than the adjacent unaffected enamel. They should not be restored unless they are esthetically objectionable.

Dentin/Pulp Complex Development

- mesenchymal origin - Odontoblasts remain in pulp

What are the three distinctly different clinical sites for caries initiation?

A. Pits and Fissures B. Smooth Enamel Surfaces C. Root Surfaces

Caveated Enamel Lesion

Active Caries

Zone 2: Affected Dentin

Also called inner carious dentin • A zone of demineralization of intertubular dentin and of initial formation of fine crystals in the tubule lumen at the advancing front. • Damage to the odontoblastic process is evident. • Softer than normal dentin and shows loss of mineral from intertubular dentin and many large crystals in the lumen of the dentinal tubules. • Stimulation of affected dentin produces pain. • Collagen cross-linking remains intact in this zone. • The intact collagen can serve as a template for remineralization of intertubular dentin, and this region remains capable of self-repair, provided that the pulp remains vital. • The affected dentin zone can also be subclassified in three sub-zones: (1) subtransparent dentin (2) transparent dentin (3) and turbid dentin.

Caries dev. in Dentin

Carious dentin undergoes several changes. The most superficial infected zone of carious dentin (3) is characterized by bacteria filling the tubules and granular material in the intertubular space. The granular material contains very little mineral and lacks characteristic cross-banding of collagen. As bacteria invade dentinal tubules, if carbohydrates are available, they can produce enough lactic acid to remove peritubular dentin. This doubles or triples the outer diameter of the tubules in infected dentin zone. Pulpal to (below) the infected dentin is a zone where the dentin appears transparent in mounted whole specimens. This zone (2) is affected (not infected) carious dentin and is characterized by loss of mineral in the intertubular and peritubular dentin. Many crystals can be detected in the lumen of the tubules in this zone. The crystals in the tubule lumen render the refractive index of the lumen similar to that of the intertubular dentin, making the zone transparent. Normal dentin (1) is found pulpal to (below) transparent dentin.

Caries Risk Assessment

Gather Data on current and recent dental history *Interview patient to determine risk factors *Conduct tests to determine status of saliva, bio- load, and any other pertinent data. *Establish a risk level for each patient that indicates their level of risk to develop new lesions. *Establish a caries treatment plan or protocol.

Reaction to severe rapidly advancing caries

High levels of acid production overpowers dentinal defenses and results in: • Infection, • Abscess, and • Death of the pulp, usually due to impaired blood supply.

Modern Practice Model

In a modern practice model, the restoration of a caries lesion should no longer be considered a cure for dental caries. Rather, the practitioner must identify patients who have active caries lesions and patients at high risk for caries and institute appropriate preventive and treatment measures.

Dry Mouth/xerostomia

In cases of dry mouth, or xerostomia, a salivary analysis is a predictive risk factor for root caries in older patients with recession and for increased caries in general in other populations.

Remineralized Enamel Lesion

Inactive Caries

Advanced Caries Lesion

Increasing demineralization of thebody of the enamel lesion results in the weakening and eventual collapse of the surface enamel. The resulting cavitation provides an even more protective and retentive habitat for the cariogenic biofilm, accelerating the progression of the lesion. TheDEJ provides less resistance to the carious process than either enamel or dentin. • The resultant lateral spread of the lesion at the DEJ produces the characteristic second cone of caries activity in dentin.

Third stage of caries in Pits & Fissures

Initial cavitation of the opposing walls of the fissure cannot be seen on the occlusal surface. Opacification can be seen that is similar to the previous stage. Remineralization of the enamel because of trace amounts of fluoride in the saliva may make progression of pit-and-fissure lesions more difficult to detect.

Xerostomia

Radiation-induced xerostomia (dry mouth) can lead to clinical caries development in 3 months from the onset of the radiation

Why are root caries more prevalent now?

Recently, prevalence of root caries has increased significantly because of the increasing number of older persons who retain more teeth, experience gingival recession, and usually have cariogenic biofilm on the exposed root surfaces.

Risk Indicator vs. Risk Factor

Risk Indicator: more likely to have more decay (best indicator that you are going to get new decay is if you have decay today!) Risk Factor: drinking sugary drinks etc.

Root Caries

Root caries lesions have less well-defined margins, tend to be U-shaped in cross-section, and progress more rapidly because of the lack of protection from an enamel covering

Salivary Analysis

Salivary flow rate, buffering capacity, and pH all can be measured by different tests and means. The predictive value for these tests for caries is not supported by the highest evidence in all circumstances. Patients with good saliva flow and adequate buffering can still have caries.

Tooth Centered Care

Tooth Centered is surgical intervention to eliminate cavitated lesions.

Fourth stage in Pits & Fissures

Extensive cavitation of the dentin and undermining of the covering enamel darken the occlusal surface

Zone 3: Infected Dentin

*carious layer, the layer that the clinician would encounter first when opening a lesion* • The zone of bacterial invasion and is marked by widening and distortion of the dentinal tubules, which are filled with bacteria. • Little mineral is present, and the collagen in this zone is irreversibly denatured. • The dentin in this zone does not self-repair. • This zone cannot be remineralized, and its removal is essential to sound, successful restorative procedures and the prevention of spreading the infection.

Enamel Development

- epithelial origin - Ameloblasts extinct after deposition

Three levels of reaction in pulp-dentin complex caries reaction

(1) reaction to a long-term, low-level acid demineralization associated with a slowly advancing lesion (2) reaction to a moderate-intensity attack (3) reaction to severe, rapidly advancing caries characterized by very high acid levels

What are the steps of caries control restoration?

(1) removing the infected tooth structure (2) medicating the pulp, if necessary (3) restoring the defect(s) with a temporary material. With this technique, most of the infecting organisms and their protecting sites are removed, limiting further acute spread of caries throughout the mouth. The caries-control procedure must be accompanied by other preventive measures.

Dentin Dev.

(A) As dentin grows, odontoblasts become increasingly compressed in the shrinking pulp chamber, and the number of associated tubules becomes more concentrated per unit area. The more recently formed dentin near the pulp (a) has large tubules with little or no peritubular dentin and calcified intertubular dentin filled with collagen fibers. Older dentin, closer to the external surface (b), is characterized by smaller, more widely separated tubules and a greater mineral content in intertubular dentin. The older dentin tubules are lined by a uniform layer of mineral termed peritubular dentin. These changes occur gradually from the inner surface to the external surface of the dentin. Horizontal lines indicate predentin; diagonal lines indicate increasing density of minerals; darker horizontal lines indicate densely mineralized dentin and increased thickness of peritubular dentin. The transition in mineral content is gradual.

How to detect a Cavitated Enamel Lesion

(Active Caries) Surface is disturbed or missing. • Soft, chalky surface discernible with an explorer • Cavitated enamel lesions lose most of the original crystalline framework of the enamel rods. *Can not remineralize, must be restored*

What should you recommend to patients with high risk for root caries?

* use of powered toothbrushes. It is critical that patients susceptible to root caries practice meticulous oral hygiene. However, many of these patients have physical and visual deficiencies, and this makes it difficult for them to adequately cleanse the mouth. For these patients, a powered toothbrush may be advantageous *Restore all root caries lesions with a fluoride-releasing material. Resin-modified glass ionomer materials are preferred for definitive restorations primarily because they bond effectively to both enamel and dentin and they act as reservoirs for fluoride which can be re-released into the oral

Go over the caries risk assessment forms!

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What are the factors that influence caries risk?

*General Health *Diet *Oral Hygiene *Fluoride Exposure *Immunization (Caries) * Function of Saliva *Antimicrobial Agents *Calcium and Phosphate Compounds *Probiotics *Sealants *Restorations

What are the four primary strategies for the prevention of root caries?

1) try to improve salivary flow rates and increase the buffering capacity 2) try to reduce the numbers of cariogenic bacteria (S. mutans) in the oral cavity. 3)reduce the quantity and numbers of exposures of ingested refined carbohydrates. 4) attempt to remineralize noncavitated lesions and prevent new lesions from developing.

What is the composition of enamel?

1-2% protein 4-8% water 90-95% inorganic (HA) --> mineralized

When is the peak rate for the incidence of new lesions occur?

3 years after the eruption of the tooth

What is the composition of Dentin?

50 vol% HA --> (75% weight) 25% vol Collagen--> (20% weight) 25 vol% water includes tubules --> (5% weight)

Zones of Dentin Caries

Caries advancement in dentin proceeds through three changes: (1) Weak organic acids demineralize dentin (2) The organic material of dentin, particularly collagen, degenerates and dissolves (3) The loss of structural integrity is followed by invasion of bacteria

Why do caries advance more rapidly in Dentin?

Caries advances more rapidly in dentin than in enamel because dentin provides much less resistance to acid attack owing to less mineralized content.

Caries development in compromised pt's

Caries development in healthy individuals is usually slow compared with the rate possible in compromised persons.

Why is demineralization likely in exposed dentin?

Critical pH for dentin is higher than for enamel, so demineralization is likely to start even before the pH reaches the critical level for enamel (pH = 5.5).

White Spot Lesion Overview

Demineralized but not cavitated. • Disappear when wet. • Chalky, white when desiccated. • Hard external surface. • Do not restore. • Proximal lesions in enamel. • When a proximal lesion is clearly visible radiographically, the lesion may have advanced significantly, and histologic alteration of the underlying dentin probably already has occurred, whether the lesion is cavitated or not. • Noncavitated enamel lesions retain most of the original crystalline framework of the enamel rods, and the etched crystallites serve as nucleating agents for remineralization. *Noncavitated caries of enamel can remineralize*.

Dentin characteristics

Dentin contains much less mineral and possesses microscopic tubules that provide a pathway for the ingress of bacteria and egress of minerals. •Because of these characteristics, dentinal caries is V-shaped in cross- section with a wide base at the DEJ and the apex directed pulpally. •Caries produces a variety of responses in dentin, including pain, sensitivity, demineralization, and remineralization.

Dental Exam

Determines risk indicators more than risk factors.Many of the indicators are directly related to the current caries activity . *Indicators and current caries activity drive the decision making process for the type of intervention. *Visible cavitated caries lesions,white spots on teeth, and brown spots on teeth are all indicators for caries risk. *Visible plaque or biofilm can be considered a risk factor for caries development. Other examination findings that would influence increased risk for caries are exposed root surfaces, deep pits or grooves, fixed, removable prosthesis, or orthodontic appliances used, poor quality existing restorations with open contacts, open margins, or overhangs.

What is a key indicator of a white spot lesion?

Disappear when wet

Zones of dentin

During caries excavation, the goal is to remove only infected dentin, while affected dentin is remineralizable and can be maintained. For orientation of layers on tooth.

Remineralization Cycles

Enamel interacts with its fluid environment in periods of undersaturation and supersaturation. Undersaturation periods dissolve most soluble mineral at the site of cariogenic attack, whereas periods of supersaturation deposit most insoluble minerals if their ionic components are present in immediate fluid environment. As a result, under favorable conditions of remineralization, each cycle could lead toward higher enamel resistance to a subsequent challenge.

Pits & Fissures: Bacteria

Large variations exist in the microflora found in pits and fissures, suggesting that each site can be considered a separate ecologic system

Smooth Enamel Surface Caries

Lesions starting on smooth enamel surfaces have a broad area of origin and a conical, or pointed, extension toward the DEJ. The path of ingress of the lesion is roughly parallel to the long axis of the enamel rods in the region. A cross-section of the enamel portion of a smooth-surface lesion shows a V-shape, with a wide area of origin and the apex of the V directed toward the DEJ. After caries penetrates the DEJ, softening of dentin spreads rapidly laterally and pulpally.

Reaction to a moderate-intensity attack

More intense caries activity results in bacterial invasion of dentin by a wide variety of pathogenic materials or irritants, including high acid levels, hydrolytic enzymes, bacteria, and bacterial cellular debris. • Can cause the degeneration and death of odontoblasts and a mild inflammation of the pulp. • Cause formation (from undifferentiated mesenchymal cells) of replacement odontoblasts (secondary odontoblasts). • These cells produce reparative dentin (reactionary dentin) on the affected portion of the pulp chamber wall • The structure of reparative dentin varies from well-organized tubular dentin (less often) to very irregular atubular dentin (more often • An effective barrier to diffusion of material through the tubules and is an important step in the repair of dentin. Severe stimuli also can result in the formation within the pulp chamber of unattached dentin, termed pulp stones, in addition to reparative dentin. • The success of dentinal reparative responses depends on the severity of the caries attack and the ability of the pulp to respond. The pulpal blood supply may be the most important limiting factor to the pulpal responses.

What kind of bacteria are frequently found in the pits and fissures of newly erupted teeth?

Numerous gram-positive cocci, especially S. sanguis

What cavitates more quickly, pit/fissures or smooth surfaces?

Occlusal pit-and-fissure lesions develop in less time than smooth-surface caries.

Why is it difficult to diagnose caries?

Pit-and-fissure caries expands as it penetrates into the enamel The entry site may appear much smaller than the actual lesion, making clinical diagnosis difficult. Caries lesions of pits and fissures develop from attack on their walls. Progression of the dissolution of the walls of a pit-and-fissure lesion is similar in principle to that of the smooth- surface lesion because a wide area of surface attack extends inward, paralleling the enamel rods. A lesion originating in a pit or fissure affects a greater area of the DEJ than does a comparable smooth-surface lesion. In cross-section, the gross appearance of a pit-and-fissure lesion is an inverted "V" with a narrow entrance and a progressively wider area of involvement closer to the DEJ.

White spot lesions

Poor oral hygiene and frequent exposures to sucrose- containing or acidic food can produce noncavitated ("white spot") lesions (first clinical evidence of demineralization) in 3 weeks.

Strategies for prevention

Preventive treatment methods are designed to limit tooth demineralization caused by cariogenic bacteria, preventing cavitated lesions. (1) limiting pathogen growth and altering metabolism (2) increasing the resistance of the tooth surface to demineralization (3) increasing biofilm pH. A caries prevention and management program is a complex process involving multiple interrelated factors

Dentin Caries

Progression of caries in dentin is different from progression in the overlying enamel because of the structural differences of dentin.

Partial Caries Excavation and Indirect Pulp Capping

Teeth that have large caries lesions but no overt pulpal or periapical pathology should be managed conservatively. *It is generally not advisable to initiate definitive root canal therapy for asymptomatic teeth with a healthy pulp and healthy periapical area. * Growing clinical and scientific evidence indicates that large carious lesions with healthy pulpal and periapical tissues should be managed via partial caries excavation and indirect pulp capping. *Aggressive complete caries removal that invades the pulp space and forces a decision of definitive root canal treatment or extraction in the context of caries control is to be avoided. *Partial caries excavation followed by indirect pulp capping via placement of a sedative restoration has significant benefits.

What area has the least resistance to caries attack?

The DEJ allows rapid lateral spreading when caries penetrate the enamel

What is the caries lesion a product of?

The caries lesion is the product of disequilibrium between the demineralization and remineralization processes

Zone 1: Normal Dentin

The deepest area is normal dentin, which has tubules with odontoblastic processes that are smooth, and no crystals are present in the lumens. The intertubular dentin has normal cross-banded collagen and normal dense apatite crystals. No bacteria are present in the tubules. Stimulation of dentin (e.g., by osmotic gradient [from applied sucrose or salt], a bur, a dragging instrument, or desiccation from heat or air) produces a sharp pain.

First stage of caries in Pits & Fissures

The initial lesions develop on the lateral walls of the fissure. Demineralization follows the direction of the enamel rods, spreading laterally as it approaches the dentinoenamel junction (DEJ).

Physical Properties of Pits and Fissures & Bacteria

The long, narrow fissure prevents adequate biofilm removal Considerable morphologic variation exists in these structures. Some pits and fissures end blindly, others open near the dentin, and others penetrate entirely through the enamel.

Appearance of Dentin Zones

The occlusal enamel appears intact, with a small opening in the occlusal fissure. Enamel is darkened where it is undermined by demineralization. The surface of enamel is unaffected. The lesion is filled with a bacterial plug containing high numbers of mutans streptococci (MS) and lactobacilli. Dentin is infected below the plug. Deeper dentin is not infected but is extensively demineralized. Reparative dentin is being formed below the lesion.

What is the driving force of remineralization?

The supersaturation of saliva with calcium and phosphate ions serves as the driving force for the remineralization process.

What is the progression time for cavitation on smooth surfaces?

The time for progression from non-cavitated caries to clinical caries (cavitation) on smooth surfaces is estimated to be 18 months ± 6 months. Peak rates for the incidence of new lesions occur

Why are patients with dry mouth at higher risk for caries?

These patients are more susceptible to dietary changes that are associated with lower pH foods and beverages or foods and beverages containing fermentable carbohydrates, since the protective factors of saliva are diminished in patients with xerostomia.

Bacterial Biofilm Analysis

Use of supplemental tests to analyze the bacterial component of the biofilm can help determine the patient's risk level. However, the evidence is weaker with some potential for bias by the examiners for these tests being predictive of future caries. For example, the presence of S. mutans or lactobacilli in saliva or plaque as a sole predictor for caries in primary teeth was shown to have low sensitivity but high specificity. Other means of bacterial testing still being evaluated is the measurement of adenosine triphosphate (ATP) activity of the biofilm bacteria as a surrogate measure of caries activity. Although these bacterial tests can be useful for communication with the patient and can provide insight into the type of bacteria present and the type of biofilm environment present, predictive evidence for caries from these tests need to be further studied and improved.

Non-cavitated enamel caries lesion

White spot lesion

What are the age-specific risk factors for children under 6?

presence of active caries in the primary caregiver in the past year *feeding on demand past 1 year of age * bedtime bottle or sippy cup with anything other than water *no supervised brushing; and severe enamel hypoplasia.

Smooth Enamel Surfaces

present a less favorable site for cariogenic biofilm attachment Cariogenic biofilm usually develops only on the smooth surfaces that are near the gingiva or are under proximal contacts. The proximal surfaces are particularly susceptible to caries because of the extra shelter provided to resident cariogenic biofilm owing to the proximal contact area immediately occlusal to it

What is the primary goal of caries prevention?

reduce the numbers of cariogenic bacteria and to create an environment conducive to remineralization. Prevention should start with a consideration of the overall resistance of the patient to infection by the cariogenic bacteria.

What does "Caries Control" mean

refers to an operative procedure in which multiple teeth with acute threatening caries are treated quickly

What may be the most important limiting factor to pulpal responses?

the plural blood supply

Patient Centered Care

use a medical model to control the disease process. *Caries Risk Assessment to establish Risk Level *Individual Risk Indicators *Individual Risk Factors *Protective factors *Non-surgical therapeutics and dental surgical interventions.

What is the first clinical evidence of demineralization?

white spot lesions

Hypo calcified Enamel

• Developmental white spot. • Same wet or dry. • Do not restore unless for esthetics.

Reaction to a long-term, low-level acid demineralization associated with a slowly advancing lesion

• Repair demineralized dentin by remineralization. • Early stages of caries or mild caries attacks produce long-term, low-level acid demineralization of dentin. • Direct exposure of the pulp tissue to microorganisms is not a prerequisite for an inflammatory response. Even when the lesion is limited to enamel, the pulp can be shown to respond with inflammatory cells. • Hypermineralized areas may be seen on radiographs as zones of increased radiopacity ahead of the advancing, infected portion of the lesion. (Called sclerotic dentin, shiny, dark, and hard) • This repair occurs only if the tooth pulp is vital.

What are the zones of dentin caries?

• Zone 1: Normal Dentin • Zone 2: Affected Dentin • Zone 3: Infected Dentin