The practice of dentistry extends beyond routine restorative care and oral hygiene maintenance; it also involves a keen ability to diagnose, localize, and evaluate pathological conditions of the oral cavity and surrounding structures. Accurate diagnosis is the cornerstone of successful treatment, and investigations form an essential part of this diagnostic process. Among these investigations, sensibility testing and radiographic examinations remain fundamental tools in evaluating dental vitality, diagnosing pathology, and determining the extent of disease.
Sensibility Testing: Understanding Pulp Vitality
The Concept of Vitality vs. Sensibility
When clinicians speak of vitality testing, they are essentially referring to the health of the dental pulp. However, there is often confusion between vitality and sensibility.
- Vitality refers to the true physiological state of the pulp, determined primarily by its blood supply.
- Sensibility refers to the pulp’s ability to respond to external stimuli via nerve fibers.
Most routine tests in clinical practice, such as cold tests or electric pulp testing, do not measure pulp vitality directly. Instead, they measure nerve response. This distinction is crucial because a tooth may still have a blood supply (and therefore be vital) even if it does not respond to sensibility tests. Conversely, a hypersensitive tooth may indicate an inflamed pulp, which is not necessarily healthy.
Clinical Methods of Sensibility Testing
1. Application of Cold
The cold test remains one of the simplest and most reliable methods for assessing pulp sensibility. Common agents include:
- Endo-Frost sprays
- Ethyl chloride
- Carbon dioxide snow (dry ice)
Procedure:
A pledget of cotton wool soaked with the refrigerant is applied to the dried tooth surface. The patient’s response is then evaluated:
- Normal pulp: A sharp sensation that subsides quickly once the stimulus is removed.
- Inflamed pulp (pulpitis): An exaggerated, lingering response.
- Necrotic pulp: No response.
Cold tests are quick, non-invasive, and widely accepted, though results may sometimes be misleading.
2. Application of Heat
Heat testing is less frequently used but can be helpful in diagnosing pulpitis, especially when the patient complains of pain exacerbated by hot food or drinks.
Procedure:
A heated gutta-percha stick is applied to the tooth surface after protecting the enamel with petroleum jelly to prevent sticking.
- Positive response: Pain that lingers after the stimulus is removed, suggesting irreversible pulpitis.
- No response: Could indicate necrotic pulp.
This test is considered less reliable than cold testing, but it can reproduce a patient’s characteristic symptoms, which makes it valuable in some cases.
3. Electric Pulp Testing (EPT)
Electric pulp testers apply a mild current to the tooth surface to stimulate nerve fibers within the pulp. A conducting medium such as toothpaste or a special gel ensures proper contact.
Advantages:
- Can localize sensibility in multi-rooted teeth.
- Provides numerical readings for comparative purposes.
Limitations:
- Measures nerve response, not true vitality.
- Readings vary depending on electrode placement, moisture, patient anxiety, and battery strength.
Interpretation:
- Early, exaggerated response → inflamed pulp.
- No response → possible necrosis or heavily calcified pulp.
Misleading results that may occur:
- False positives: Multi-rooted teeth with one necrotic canal, pus-filled canals, anxious patients.
- False negatives: Recently traumatized teeth, secondary dentine, large restorations.
4. Test Cavity
The test cavity is considered the most definitive, though invasive, method.
Procedure:
- Drilling is performed into dentine without local anesthesia (LA).
- If the pulp is vital, the patient should feel pain.
Because it involves permanent destruction of tooth structure, this test is regarded as a last resort, especially in crowned or heavily restored teeth where other tests are inconclusive.
5. Percussion Testing
Percussion is carried out by tapping gently on the suspect tooth with the blunt end of a mirror handle. It helps in detecting periapical inflammation rather than pulpal pathology.
Positive response: Pain or tenderness, indicating inflammation in the periodontal ligament, often associated with an apical abscess.
Percussion testing is not a direct pulp test but is invaluable in differentiating between pulpal and periapical disease.
6. Tooth Mobility
Tooth mobility testing evaluates the periodontal support around a tooth. Increased mobility may indicate:
- Periodontal disease
- Periapical pathology
- Vertical root fracture
Mobility is graded clinically, with grade III indicating severe mobility and poor prognosis.
7. Palpation
Palpation of the buccal sulcus adjacent to a tooth can detect periapical swelling, tenderness, or the presence of an abscess. It provides additional diagnostic evidence when combined with percussion and radiography.
8. Biting Tests
Biting on objects such as:
- Tooth Slooth device
- Cotton roll
- Wooden stick or rubber
These can reveal pain associated with cracked tooth syndrome or fractured cusps. Patients often report sharp, localized pain on release of biting pressure.
9. Diagnostic Local Anaesthesia
When conventional methods fail, local anaesthetic infiltration can help localize the source of pain. If anesthesia of a suspect tooth relieves symptoms, the diagnosis is confirmed. This is particularly useful when multiple teeth are tender or when pain referral complicates the clinical picture.
Radiographic Investigations in Dentistry
Radiographs complement sensibility tests by providing structural information about teeth and surrounding bone.
Importance of Radiographs
- Detect caries and restorations.
- Evaluate periodontal bone loss.
- Identify periapical pathology.
- Aid in treatment planning for extractions, implants, and orthodontics.
- Assist in localizing unerupted or impacted teeth.
Radiographic Choice for Different Areas
The appropriate radiographic views for different clinical needs:
- General scan of teeth and jaws → Dental Panoramic Tomograph (DPT).
- Localization of unerupted teeth → Parallax periapicals.
- Crown and interdental bone (caries, restorations) → Bitewing, periapicals.
- Root and periapical area → Periapical radiograph.
- Submandibular gland → Lower occlusal view.
- Sinus → Occipito-mental view, DPT.
- Temporomandibular joint (TMJ) → DPT, MRI.
- Skull and facial bones → Occipito-mental, PA and lateral skull, Submento-vertex.
Limitations and Challenges
While sensibility tests and radiographs are indispensable tools, they have limitations:
- Sensibility tests cannot measure true vitality (blood supply).
- False-positive and false-negative results can mislead diagnosis.
- Radiographs provide two-dimensional images, sometimes obscuring small lesions.
- Radiation exposure, though minimal, must be justified.
Emerging technologies such as laser Doppler flowmetry and pulse oximetry offer promise for measuring true pulpal vitality by assessing blood flow, but these methods are not yet widely available in routine practice.
Clinical Scenarios
1. Acute pulpitis
- Exaggerated lingering response to cold.
- Sharp pain on heat application.
- Radiograph may be normal or show widened periodontal ligament space.
2. Chronic pulpitis
- Dull pain, minimal or no response to cold.
- Electric pulp tester may give delayed response.
3. Periapical abscess
- Severe tenderness on percussion.
- Palpation reveals swelling.
- Radiograph shows radiolucency at apex.
4. Cracked tooth syndrome
- Pain on biting/release.
- Radiographs often inconclusive; sensibility tests essential.
Conclusion
Accurate diagnosis in dentistry relies heavily on a systematic approach combining clinical sensibility testing and radiographic assessment. Each test has its advantages and limitations, and no single method is completely reliable on its own. Instead, a combination of investigations, interpreted in the context of the patient’s symptoms and history, provides the most accurate diagnostic outcomes.
While traditional methods like cold testing, percussion, and radiographs remain central to practice, technological advances promise to refine our ability to measure true pulp vitality. Until then, careful interpretation and clinical judgment will remain the most important diagnostic tools in the dentist’s armamentarium.
References
- Hargreaves KM, Berman LH (eds.)
Cohen’s Pathways of the Pulp. 12th ed. St. Louis: Elsevier; 2021.
→ Comprehensive coverage of pulp biology, vitality testing, and endodontic diagnosis. - Pitt Ford TR, Patel S.
Endodontics: Problem-Solving in Clinical Practice. 2nd ed. London: Elsevier; 2016.
→ Discusses diagnostic techniques, electric pulp testing, and interpretation of results. - Summitt JB, Robbins JW, Hilton TJ, Schwartz RS.
Fundamentals of Operative Dentistry: A Contemporary Approach. 4th ed. Hanover Park, IL: Quintessence Publishing; 2013.
→ Offers insights into tooth structure, vitality, and restorative implications of diagnosis. - Ingle JI, Bakland LK, Baumgartner JC.
Ingle’s Endodontics. 7th ed. Hamilton: BC Decker; 2019.
→ Authoritative reference on diagnostic testing, pulp and periapical disease, and radiography. - European Society of Endodontology (ESE).
“Quality guidelines for endodontic treatment: Consensus report.” International Endodontic Journal. 2006;39(12):921-930.
→ Evidence-based recommendations for pulp vitality assessment and radiographic use. - American Association of Endodontists (AAE).
Guidelines for the Assessment of Pulpal and Periapical Conditions. Chicago: AAE; 2020.
→ Official guidelines on vitality testing, radiographic protocols, and diagnostic procedures. - White SC, Pharoah MJ.
Oral Radiology: Principles and Interpretation. 8th ed. St. Louis: Mosby Elsevier; 2019.
→ The definitive text on dental imaging techniques, including periapical, panoramic, and occlusal radiographs. - Grossman LI, Oliet S, Del Rio CE.
Endodontic Practice. 11th ed. Philadelphia: Lea & Febiger; 1988.
→ Classic reference discussing traditional vitality testing and interpretation of results. - Ricucci D, Siqueira JF Jr.
“Biofilms and apical periodontitis: Study of prevalence and association with clinical and histopathologic findings.” Journal of Endodontics. 2010;36(8):1277-1288.
→ Correlates clinical testing with histopathological findings in periapical disease. - Nixon PJ, Gahan M, Robinson S.
Advanced Endodontics: Clinical Retreatment and Surgery. 1st ed. London: CRC Press; 2015.
→ Includes advanced diagnostic imaging and vitality assessment.