Hydrodynamic Theory
Explain the hydrodynamic theory of dentin hypersensitivity and identify the primary researcher associated with its modern formulation.
Hydrodynamic theory: stimuli on dentin surface cause fluid movement in dentinal tubules, activating mechanoreceptors/nerve endings; Brännström credited.
List five common stimuli that can elicit dentin hypersensitivity (provide categories, not individual foods).
Tactile, thermal, evaporative, osmotic, chemical.
State two features that help distinguish hypersensitivity pain from pulpal pain.
Hypersensitivity: stimulus-evoked, brief, stops when stimulus removed; pulpal pain: spontaneous, throbbing, may not require stimulus.
Give two primary goals of treating dentin hypersensitivity.
Pain relief and modify/eliminate contributing factors.
Recommend three oral hygiene modifications to reduce hypersensitivity risk that can be taught to patients.
Use soft/ultra-soft brush, gentle technique, avoid immediate brushing after acidic intake.
Describe how dentinal tubule morphology (diameter and density) correlates with hypersensitivity according to the hydrodynamic model.
Wider and more numerous tubules (especially near pulp) increase fluid movement and sensitivity.
Explain how gingival recession leads to increased dentin exposure and name three behavioral contributors to recession.
Recession exposes root surface; contributors: aggressive brushing, narrow attached gingiva, periodontal therapy/trauma.
Name four diagnostic tests or clinical assessments that aid differential diagnosis of tooth pain related to hypersensitivity.
Visual exam, percussion, thermal testing, radiographs, bite tests, transillumination for cracks.
List three categories of desensitizing agents used clinically and give one mechanism of action for each.
Potassium salts (reduce nerve excitability), fluorides (promote remineralization & tubule occlusion), oxalates (precipitate and occlude tubules), glutaraldehyde (protein coagulation), calcium phosphates (remineralize/occlude).
Explain the role of dietary modifications in both causing and mitigating hypersensitivity; include specific timing advice related to brushing.
Reduce acidic food/drink frequency, rinse with water after acids, wait before brushing to allow remineralization.
Outline an experimental design to test the hydrodynamic theory in vitro using extracted human teeth. Include controls and measurable outcomes.
Experimental design: use extracted teeth with standardized smear layers; apply controlled thermal/evaporative stimuli; measure fluid flow or intra-tubular pressure and record neural surrogate responses; include sealed-tubule controls and tubule‑widened specimens.
Define abfraction and describe how occlusal forces produce the characteristic lesion associated with it.
Abfraction: flexural microfracture at cervical margin from occlusal loading causing V-shaped lesions.
Given a case: patient reports sharp brief pain to cold on mandibular premolars, radiographs normal, percussion negative — outline a stepwise diagnostic plan (questions, tests) to confirm hypersensitivity and rule out other causes.
Stepwise plan: focused interview, visual inspection, isolation/drying, targeted thermal stimulation, tactile probe, radiographs, rule out cracked tooth (bite test) and caries.
Compare and contrast in-office (professional) and at-home (self-applied) desensitizing strategies, including typical active ingredients and indications.
In‑office: varnishes, bonding agents, glutaraldehyde, lasers; at‑home: desensitizing toothpaste (potassium nitrate, fluoride), fluoride gels/trays. Indications depend on severity and location.
Create a short counseling script (3–4 sentences) for a patient who complains of sensitivity after scaling and root planing.
Script: “You may experience temporary sensitivity after scaling because the calculus that coated the roots was keeping tubules partially blocked. This often improves over weeks; use a desensitizing toothpaste and return if severe or persistent.”
Discuss how changes in fluid viscosity within dentinal tubules would theoretically affect stimulus transmission and pain perception according to the hydrodynamic theory.
Increased viscosity → reduced fluid movement → decreased mechanoreceptor stimulation → less pain (theoretically).
Discuss the multifactorial process by which acidic diet and toothbrushing sequence can accelerate enamel/cementum loss and lead to hypersensitivity.
Acid softens enamel/cementum; brushing during this softened state causes abrasion; frequent acid exposure increases cumulative loss.
Describe how you would use thermal and electric pulp testing results to differentiate reversible pulpitis, irreversible pulpitis, and hypersensitivity.
Reversible pulpitis: lingering pain to cold but responsive; irreversible: spontaneous severe lingering pain; hypersensitivity: brief sharp pain that ceases when stimulus removed.
Describe a treatment algorithm that progresses from conservative to more invasive approaches, specifying decision points and when to escalate care.
Algorithm: identify & eliminate cause → recommend behavior/diet modifications & desensitizing toothpaste → apply in-office agents if persistent → consider restorative coverage if structural defect present.
Identify psychosocial impacts of chronic dentin hypersensitivity and suggest two strategies dental professionals can use to address these with patients.
Chronic pain can cause anxiety/depression; strategies: validate experience, set realistic expectations, provide self-care tools, and consider referrals for pain management if needed.
Critically evaluate alternative mechanisms proposed historically for dentin hypersensitivity and argue why hydrodynamic theory remains the most accepted. Cite strengths and limitations.
Alternatives include direct nerve exposure theories; hydrodynamic supported by morphology and experimental data but limited by indirect measurement of neural activation.
Analyze how systemic conditions (e.g., gastroesophageal reflux disease, bulimia) contribute to dentin exposure and describe an evidence-based prevention strategy for dental professionals to advise these patients.
Systemic acids demineralize enamel/cementum; prevention: manage reflux medically, advise rinsing w/ water or sodium bicarbonate, delay brushing 30–60 minutes after acid exposure, fluoride therapy.
Present a differential-diagnosis matrix comparing signs, symptoms, and test findings for: dentin hypersensitivity, cracked tooth syndrome, reversible pulpitis, and root surface caries.
Matrix: provide key distinguishing test results (see above).
Design a randomized controlled trial to compare the effectiveness of a 5% potassium nitrate toothpaste versus a fluoride varnish in reducing sensitivity over 12 weeks. Include primary outcome measure(s), sample selection criteria, blinding considerations, and an outline of statistical analysis.
RCT design: primary outcome = patient-reported sensitivity score reduction (e.g., VAS) at 12 weeks; randomized, double-blind; include power calculation, ANCOVA or mixed-models for repeated measures.
Draft a comprehensive posttreatment instruction sheet (bulleted) for a patient after receiving a professional desensitizing procedure, including monitoring, self-care, and when to return for follow-up.
Posttreatment sheet: avoid abrasive toothpaste for X days, use prescribed fluoride gel/tray nightly for Y weeks, avoid highly acidic foods, report sustained or worsening pain, follow-up in Z weeks.