Preventive and Desensitizing Dental Materials

Preventive and Desensitizing Materials

Introduction to Prevention and Dental Professionals

• Role of Expanded Function Dental Assistants and Hygienists: These professionals play crucial roles in disease prevention and maintaining patient health in collaboration with the dentist.

• Important Preventive Measures for Caries Management: The primary methods discussed include fluorides, antibacterial mouth rinses, and sealants.

Fluoride and Caries Control

What is Fluoride?

• Naturally Occurring Mineral: Fluoride is naturally found in various sources, including well water, food that has absorbed fluoride from the soil, and as an additive in many over-the-counter dental products.

• Effectiveness and Safety: It is highly effective and safe in preventing dental decay, recognized as one of the greatest public health successes of the 20th century.

• Optimal Fluoride Levels: Fluoride can occur naturally or be supplemented. The accepted optimal level of fluoride in drinking water ranges from $0.7$ to $1.2\, \text{mg/L}$ (milligrams per liter) or parts per million (ppm).

Fluorosis

• Definition: Fluorosis is a condition caused by excessive fluoride intake during tooth formation.

• Causes: Common causes include eating fluoridated toothpaste or swallowing supplemental fluoride during dental treatment.

Topical and Systemic Effects of Fluoride

• Demineralization: Fluoride helps counteract the loss of tooth mineral.

• Remineralization: It promotes the repair and strengthening of tooth structure.

• Cariogenic Protection: Fluoride plays a key role in protecting against caries (dental decay).

Protection Against Erosion

• Cause: Highly acidic foods contribute to the loss of tooth mineral, a process distinct from caries as bacteria are not primarily involved.

• Location: Most mineral loss due to erosion occurs at the tooth surface.

• Medical Conditions: Certain medical conditions can also cause or exacerbate erosion.

Fluoride and Antibacterial Rinses for Caries Control

• Combined Approach: Fluoride alone is not always sufficient in managing dental caries. Its effectiveness is enhanced when used in conjunction with antibacterial mouth rinses.

• Chlorhexidine Gluconate:

  • A prescription antibacterial rinse.

  • Maximum concentration allowed by the FDA is $0.12\%$.

  • Substantivity: It has a prolonged antibacterial effect (substantivity).

  • Side Effects: Can cause brown staining on teeth, tongue, and composite restorations.

Methods of Fluoride Delivery

• Dietary Fluoride Supplements: Taken systemically.

• In-Office Fluoride Applications (Topical):

  • Gels and Foams

  • Varnish

• Self-Applied Topical Gels and Pastes: Used at home.

• Over-the-Counter Fluoride Rinses: Available for daily use.

• Fluoride-Containing Toothpaste: The most common daily source of topical fluoride.

• Fluoride-Containing Prophylaxis Pastes: Used by dental professionals during cleanings.

In-Office Topical Gels and Foams

• APF (Acidulated Phosphate Fluoride):

  • Most often used in children.

  • Contains $12,300\, \text{ppm}$ fluoride.

  • Provides good fluoride uptake with enamel.

  • Cautions: Can etch composite restorations and worsen root sensitivity by dissolving plugs in dentinal tubules.

• Two Percent Neutral Sodium Fluoride (NaF):

  • Contains $9000\, \text{ppm}$ fluoride.

  • Used more often in adults.

  • Advantage: Less likely than APF to etch the surface of restorations made of porcelain, composite resin, glass ionomer, or compomer due to the absence of phosphoric acid.

Fluoride Varnish

• Application: Applied directly onto the tooth surfaces.

• Advantages: Holds fluoride against the tooth surface for a longer duration compared to other products.

• Availability: Available in $5.0\%$-sodium fluoride, providing $22,600\, \text{ppm}$.

• Retention and Release: Can remain on teeth for $1$ to $3$ days with gentle brushing. Peak fluoride release occurs within the first $5$ minutes, with high levels sustained for $2$ to $4$ hours.

• Trend: Rapidly replacing foams and gels as the preferred in-office topical fluoride application method.

Safety of Fluoride Applications

• Usage: Must be used only as directed.

• Children: Keep fluoride products away from small children. The lethal dose for a child weighing $20$ pounds is approximately $700$ to $1500\, \text{mg}$ of sodium fluoride.

Self-Applied Topical Gels and Pastes

• Indications: Recommended for patients at high risk for dental caries, orthodontic patients to prevent decalcification, elderly patients with xerostomia (dry mouth) due to medications (who are at high caries risk), and those with exposed root surfaces.

• Availability: Available by prescription as $1.1\%$-neutral sodium fluoride ($5000\, \text{ppm}$) or $0.4\%$-stannous fluoride ($900\, \text{ppm}$).

Pit and Fissure Sealants

Purpose and Composition

• Material: Sealants are unfilled or lightly filled resins.

• Function: Their primary purpose is to prevent dental caries in the pits and fissures of teeth.

• Location: Primarily applied to the occlusal surfaces of posterior teeth.

• Indications: Not all teeth require sealants. They are recommended for teeth with steep cuspal inclines and deep, sticky fissures that are prone to caries.

Composition of Sealants

• Similarity to Composites: Sealants have a composition similar to composite resins.

• Resin Components: Based on dimethacrylate monomers such as Bisphenol A-glycidyl methacrylate (bis-GMA) and Urethane dimethacrylate (UDMA).

• Polymerization: The material undergoes polymerization (hardening).

• Filler Particles: Contain small filler particles to enhance strength and wear resistance.

Working Time and Curing

• Self-Cured Sealant: Sets through a chemical reaction over time.

• Light-Cured Material: Polymerizes when exposed to a specific wavelength of light, offering more control over working time.

Color and Wear

• Appearance: Available in a variety of colors, including clear, tinted, and opaque.

• Maintenance: Should be examined at each dental visit for stability and potential wear from occlusion.

Sealant Placement Steps

• Attention to Detail: Proper sealant placement requires meticulous attention to detail through multiple steps:

  1. Clean Surface: The tooth surface is cleaned with pumice.

  2. Etch Enamel: Enamel is etched with $37\%$-phosphoric acid to create microscopic porosities for mechanical retention.

  3. Rinse: The etched surface is thoroughly rinsed with water.

  4. Dry Enamel: The enamel is completely dried to ensure proper adhesion.

  5. Bonding (Optional): A bonding agent may be applied (optional step).

  6. Place Sealant: The sealant material is carefully applied to the pits and fissures.

  7. Cure: The sealant is cured, typically with a curing light.

  8. Wipe Cured Surface: The cured surface is wiped with gauze or a cotton roll to remove the oxygen-inhibited layer.

Desensitizing Agents

Causes of Tooth Sensitivity

• Mechanism: Sensitivity arises from exposed dentinal tubules to the oral cavity.

• Triggers: Common triggers include:

  • Temperature (usually cold).

  • Sweet foods (sugar).

  • Acidic foods.

  • Exposed root structure due to gum recession or abrasion.

Treatment for Sensitivity

• Goal: Desensitizing agents are used to reduce or eliminate tooth sensitivity.

• Two Main Modalities:

  1. Occluding (Plugging) Open Tubules: Blocking the openings of the dentinal tubules to prevent fluid movement that irritates the nerve.

  2. Desensitizing Nerve Endings: Directly affecting the nerve within the pulp to reduce pain signals.

Various Desensitizing Agents

• Toothpastes: Many over-the-counter toothpastes contain desensitizing agents (e.g., potassium nitrate).

• Fluoride Gels and Varnishes: Can help occlude tubules and strengthen enamel.

• Inorganic Salt Solutions: Such as strontium chloride.

• Resin Primers and Bonding Agents: Applied by professionals to seal tubules.

• Mineralizing Agents: Products that promote the formation of mineral deposits to block tubules.

• Glass Ionomer Surface Sealer: A restorative material that can also be used to seal sensitive areas.

Remineralization Products

Process of Remineralization

• Definition: The natural repair process of the tooth structure surface, where minerals are redeposited into demineralized enamel.

How Remineralization Products Work

• Products Facilitating Remineralization:

  • Fluorides: Enhance remineralization by promoting the formation of fluorapatite, which is more acid-resistant than hydroxyapatite.

  • Amorphous Calcium Phosphate (ACP): Releases calcium and phosphate ions, which are building blocks for tooth mineral.

  • Calcium Sodium Phosphosilicate (NovaMin): A bioactive glass that reacts in saliva to release calcium, phosphate, and silica, forming a protective layer of hydroxycarbonate apatite.

• Resin Infiltration: A technique used to treat early white spot lesions (initial caries). It involves applying a low-viscosity resin into the porous enamel of the lesion, thus sealing and strengthening it without removing tooth structure.

Summary of Preventive Practices

• Scope of Dentistry: Preventive practices in dentistry extend far beyond routine cleanings and bi-annual fluoride applications.

• Caries Management: Caries can be arrested, and tooth structure remineralized, through comprehensive caries risk assessment and the topical application of fluoride.

• Occlusal Protection: Sealants are crucial for protecting the pits and fissures of teeth from decay.

• Addressing Sensitivity: Desensitizing agents are increasingly important as people retain their natural teeth longer, leading to a higher prevalence of sensitivity issues. Efforts include applying desensitizing agents to sensitive teeth and applying topical fluoride gel, foam, or varnish correctly, as permitted by state law.