Dental Problems and Hypersensitivity

Causes of Dentin Hypersensitivity

• Exposure of cementum leading to exposure of dentin and hypersensitivity
• Cracked tooth syndrome: incomplete fracture of teeth, involving dentin only or extending to pulp, resulting in teeth hypersensitivity with biting relieved with releasing
• Trauma: fracture of enamel, dentin, or root
• Preoperative etiological factors:
  • Bacterial
  • Chemical - Osmotic
  • Mechanical
  • Thermal
  • Idiopathic
• Postoperative (Iatrogenic) factors:
  • Cavity preparation
  • Restorative phase and restorations
  • Vital teeth bleaching

Types of Dentin Hypersensitivity

• Reversible hypersensitivity: subsides by treating the exposed dentin
• Irreversible hypersensitivity: might require root canal treatment or even extraction of the teeth in some severe cases

Factors Affecting Dentin Hypersensitivity

• Instrumentation:
  • Rotary instruments produce more heat generation than hand instruments
  • Dull instruments require higher pressure and subsequently more heat generation
  • Heat can destruct pulpal tissue, coagulate protoplasm, and even burn dentin, making proper cooling mandatory
• Cutting instruments:
  • Every square millimeter of dentin cut exposes 30,000 to 45,000 dentinal tubules, resulting in fluid movement and stimulating nerve damage
• Dentin desiccation:
  • Heating of dentin during cutting
  • Use of chemicals to sterile the cavity
  • Use of air as a coolant for final cavity toilet

Restorative Phase and Restorations

• Polymerization shrinkage: results in stresses at the interface, resulting in microleakage, microcracks, and secondary caries
• Under-cured resin: incompletely cured inner layer, results in marginal fracture, open margin, and chemical toxicity
• Micro-leakage: ingress of fluids and microorganisms causes dentinal hypersensitivity due to dentinal fluid movements
• Inadequate protection: metallic restoration causes hypersensitivity, especially in the first few days
• Fractured restoration: exposed dentin, recurrent caries, and dentin hypersensitivity
• Cracked tooth: sharp pain on biting and eating citrus fruits, large restorations, and restorations without cusp protection
• Galvanism: hypersensitivity is usually felt in the tooth containing the restoration with the lower potential
• Faulty occlusal and/or proximal relationship: occlusal contact affects the periodontal ligament, leading to sensitivity with bite and/or mobility
• Finishing procedures: might lead to heat generation, scratch, or cementum loss
• Barodontology: expansion of air voids under or within a restoration or gases in a non-vital teeth in an airplane
• Gingival reaction: retraction cord and chemical tissue packs, improperly contoured or overhanging temporary dressing
• Pulpal reaction: direct pulp capping is considered successful if the tooth remains asymptomatic and gives a positive vitality test

Management of Etiological Factors

• Identify and prevent etiological factors in the treatment plan
• Home care:
  • Desensitizing toothpastes/dentifrices
  • Toothbrush and toothpaste application
  • Mouthwashes and chewing gums
  • Dietary modifications
  • Management of parafunctional habits
• In-office treatment:
  • Fluorides: sodium fluoride and stannous fluoride
  • Iontophoresis: uses electricity to enhance diffusion of ions into the tissues
  • Potassium nitrate: reduces dentin hypersensitivity by reducing nerve excitability
  • Oxalates: reduce dentin permeability and occlude tubules
  • Calcium phosphates: occlude dentinal tubules and decrease dentin permeability
  • NovaMin: bioactive glass that delivers ionic form of calcium, phosphorus, silica, and sodium for bone and tooth mineralization
  • Casein phosphopeptides: a water-based topical cream that provides extra teeth protection and neutralizes acids from acidogenic bacteria and external acid sources