Diagnosis Detective
A tooth has lingering pain to cold but no percussion or palpation sensitivity. Give the pulpal and apical diagnoses.
Symptomatic irreversible pulpitis + normal apical tissues
What pulpal nerve plexus lies immediately beneath the odontoblastic layer?
Plexus of Raschkow
What irrigant removes the inorganic portion of the smear layer but does not effectively dissolve organic tissue?
EDTA
A tooth is completely displaced from its socket. What traumatic injury occurred?
Avulsion
What is the narrowest portion of the apical root canal called?
Apical constriction/minor diameter
A tooth has no response to cold, is tender to percussion, and has no apical radiolucency. Give both diagnoses.
Pulp necrosis + symptomatic apical periodontitis
One canal leaves the chamber, divides into two, then rejoins before exiting. What Vertucci type is this?
Vertucci Type III (1-2-1)
A NiTi file fractures after repeated rotation through a curvature without binding. What caused the fracture?
Cyclic fatigue
Following luxation, a tooth becomes yellow and its pulp space progressively narrows. What process occurred?
Pulp canal obliteration
What phenomenon can trap gas in the closed apical portion of a canal and interfere with irrigant penetration?
Apical vapor lock
A previously treated tooth has an isolated narrow, deep periodontal probing defect and persistent symptoms. What major endodontic complication should be suspected?
Vertical root fracture
According to Krasner and Rankow, canal orifices are located at the junction of what two structures?
Pulp chamber wall-floor junction
The apical portion of a rotary file binds while the shank continues rotating. What failure mechanism occurs?
Torsional failure
Following replantation, a tooth develops a metallic percussion sound and progressive replacement of the root by bone. What complication occurred?
Replacement resorption/ankylosis
What anatomical structure connects two canals within the same root without extending to the external root surface?
Isthmus
A tooth responds normally to cold testing but produces pain on biting that is especially pronounced upon release. What condition should be suspected?
Cracked tooth syndrome
What anatomical structure represents the histologic transition between dentin and cementum near the root terminus and has traditionally been associated with the pulpal-periodontal transition?
Cementodentinal junction (CDJ)
During preparation of a curved canal, excessive dentin is removed from the outer apical curvature, altering the original canal path. Name the procedural error.
Canal transportation
After trauma, a tooth initially gives no response to sensibility testing. Why is this finding alone insufficient to diagnose pulp necrosis?
Trauma can temporarily disrupt neural response, so sensibility testing may produce a false-negative
A resorptive lesion shifts relative to the canal when the horizontal tube angle changes. What type of resorption does this support?
External root resorption
What key histologic feature distinguishes a true radicular cyst from a pocket/bay cyst?
True cyst is completely epithelial-lined without direct communication with the canal
Two canals leave the chamber separately and merge into one before exiting through a single foramen. What Vertucci classification is this?
Vertucci Type II (2-1)
A curved canal develops a transported apical foramen with a narrow constriction immediately coronal to it. Name both preparation errors.
Apical zip + elbow
After avulsion, extensive PDL damage results in progressive loss of the root and its substitution by alveolar bone. Name the biological process.
Replacement resorption/ankylosis
What reaction describes NaOCl's interaction with fatty acids, producing soap and glycerol?
Saponification