Endodontics and Odontogenic Pain

Endodontics

• Dental pulp is a soft connective tissue composed of cells (odontoblasts, fibroblasts, and others), vessels, and nerves
• Pulp innervation is provided by three types of trigeminal sensory nerve fibers: A-beta, A-delta, and C fibers
  • A-beta (5%) and A-delta (15%) are myelinated with fast conduction speeds and low excitability thresholds
  • C fibers (80%) are unmyelinated with slow conduction speeds and high excitability thresholds
• Pulp is richly vascularized - blood flow and plasma extravasation increase in inflamed pulp, leading to local delivery of protein-bound drugs like NSAIDs
• Central sensitization can occur alongside peripheral sensitization in response to pulpitis

Odontogenic Pain

• Myelinated afferents innervate dentinal tubules, causing sharp, bright, and stabbing pain in dentinal hypersensitivity
• Unmyelinated afferents terminate in the perivascular regions of the pulp, leading to dull aching and throbbing pain in pulpitis
• Pulpitis is primarily a localized infection by microorganisms, which can indirectly activate nociceptors through inflammatory mediators
• Increased levels of prostaglandin E2 (PGE2) are associated with pain

Mechanisms of Tooth Pain

• Hydrodynamic theory - relies on the proximity of mechanosensitive neurons to fluid movement within dentinal tubules
• Direct innervation - hydrodynamic theory doesn't account for the full range of activation seen in odontogenic pain
• Neuroplasticity - involves peripheral sensitization and plasma extravasation
• Odontoblasts as mechanoreceptors - odontoblasts express TRP channels and release signals like ATP
• Brush the outer tooth surface, then the inner tooth surface, then the chewing surface - disadvantage of non-alcohol versions is that they don't work as well

Dental Prescriptions

• In 2022, there were approximately 1.17 million dental prescriptions
• Top 15 prescribed drugs included 7 antibiotics and 1 antifungal

Infective Endocarditis

• Risk factors for infective endocarditis include repeated Group A Strep infections, Strep throat, impetigo, scabies, acute rheumatic fever, and bacteremia following dental procedures
• Acute rheumatic fever can cause an autoimmune response damaging heart valves, leading to rheumatic heart disease
• Prophylactic therapy is recommended for patients with high risk of adverse outcomes from infective endocarditis:
  • Artificial heart valves
  • History of infective endocarditis
  • Congenital heart conditions
  • Transplant with valve problems
• Recommended dose is 2g amoxicillin orally 1 hour before procedure, or clindamycin for immediate hypersensitivity to penicillin
• Prophylactic therapy is not required for all procedures, only those with high incidence of bacteremia (e.g., extractions, scaling and root planing)
• Oral hygiene of patient is important, including full mouth probing for patients with periodontitis
• Not recommended for restorations, LA administration, or probing healthy teeth

Choice of Antibiotics for Infections

• Narrow spectrum: penicillin V and amoxicillin
• Broad spectrum: co-amoxyclav (Augmentin), azithromycin, metronidazole, clindamycin
• Bactericidal: metronidazole, penicillin
• Bacteriostatic: trimethaprim, sulfonamides, tetracycline, azithromycin
• Odontogenic Infections:
  • Prevotella resistant to penicillin (Russia, Romania, Europe)
  • Dentists are the second largest prescriber of antibiotics
  • Increase in misuse and overuse of antibiotics due to:
    • Antibiotics used as feed additives in agriculture
    • Antibiotic-resistant genes as markers in GMO crops
• Antibiotic Resistance:
  • WHO declared it one of the top 10 global public health threats
  • 70% of HCAI are resistant to at least one common antibiotic
  • Increase in community-acquired infection resistance
  • Contributes to 700,000 deaths per year

Mechanisms of Antibiotic Resistance

• Innate Resistance:
  • No mechanism to transport the drug into the cell
  • Do not contain or rely on the antibiotic's target process or protein (e.g., gram- bacteria naturally resistant to beta-lactams)
• Acquired Resistance:
  • Microorganisms develop genetic mutations to resist antibiotics

Mechanisms of Drug Action

• Drugs that affect cell wall synthesis - target peptidoglycan
  • Beta-lactams and cephalosporins (penicillin and flucloxacillin)
  • Glycopeptides (vancomycin - only effective against gram-positive bacteria)
• Drugs that affect protein synthesis - prokaryote ribosomes are different from human ribosomes, interfering with mRNA binding to ribosomes during translation
  • Aminoglycosides, tetracyclines, macrolides, chloramphenicol, clindamycin
• Drugs that affect nucleic acid synthesis: structure of DNA is identical in prokaryotes and eukaryotes
  • Target enzymes absent in eukaryotes
  • E.g., quinolones

Adverse Reactions to Antibiotics

• Unexpected or unintended effects: headaches, vomiting, liver or kidney injury
• Dose-related effects: extension or side effects
• Allergic reactions: require sensitization (e.g. S. Pyogenes, clindamycin-resistant Group B strep)

Oral Hygiene

• Toothpaste:
  • Fluoride
  • Low abrasion
  • Spit, don't rinse
  • Can treat sensitive teeth or bleach teeth
  • Alternatives: tea tree, bicarbonate, xylitol
• Tongue cleaning:
  • Reduces organisms, tongue coating, and halitosis
• Water flossers:
  • Alternative to flossing for those with limited dexterity or oral appliances
  • Unclear effectiveness at plaque control

Factors Affecting Oral Hygiene Maintenance

• Patient factors:
  • Motivation
  • Manual dexterity
  • Self-esteem
• Tooth anatomy:
  • Crowding
  • Tooth surface/position in jaw
  • Proximity to frenum
  • Recession
  • Deep grooves
  • Plaque retentive anatomy

Partial Dentures

• Thorough cleaning is necessary, especially abutment teeth and clasps
• Nighttime wear can result in gingival inflammation

Iatrogenic Dental Disease (from dental interventions)

• Open contacts
• Over or under contouring restorations
• Crowns and Bridges:
  • Margins should be seamless with no gaps or overhangs to retain plaque
  • Subgingival margins are harder to clean
• Restoration overhangs:
  • Need to be removed or replaced
  • Plaque retentive
  • Avoid overhangs with effective wedging

Periodontitis Prevention

• All periodontitis is preceded by gingivitis, but not all gingivitis progresses to periodontitis
• Subgingival plaque can stimulate a destructive immune response in susceptible individuals
• Risk factors for periodontitis:
  • Diabetes (type 1 and 2)
  • Smoking
• Smoking cessation decreases the risk of periodontitis to levels seen in non-smokers

Early Detection of Periodontitis

• Gingival bleeding during toothbrushing
• Change in gingival color (redness) or shape (swelling)
• Persistent halitosis (bad breath) or bad taste
• Receding gums
• Tooth mobility or movement
• Bleeding gums are the earliest sign and should not be ignored

Mouthwash Treatment

• Chlorhexidine mouthwash for moderate-to-severe periodontitis:
  • SRP + amoxicillin / metronidazole
• Prophylaxis:
  • Used to be commonly used to reduce risk of infective endocarditis
  • Side effects and risk of resistance
  • Prescribe for patients with cardiac conditions with high risk of adverse outcomes
• C. Glabrata (less common):
  • Opportunistic pathogen
  • Risk factors:
    • Very old or very young
    • Poor health
    • Overuse of antibiotics
    • HIV infection or AIDS
    • Chemotherapy or immunosuppressive drugs
    • Taking steroid medication
    • Diabetic with high blood sugar
    • Poorly fitting dentures

This quiz covers essential concepts in endodontics, focusing on dental pulp composition, innervation, and the types of nerve fibers involved in pain perception. It also explores the mechanisms of pulpitis and related odontogenic pain types. Test your understanding of these critical dental topics.