Study guide
2.2 Hard Tissue Anomalies, Cysts, Neoplasms & Radiographic Pathology
National Board Dental Hygiene Examination NBDHE
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1 Chapter 1: Head, Neck & Dental Anatomy, Histology & Embryology
1.1 Head & Neck Cranial Nerves, Osteology & Musculature 1.2 Tooth Morphology, Occlusion & Root Anatomy 1.3 Tooth Development, Histology & Embryology 1.4 Oral Physiology, Salivary Gland Function & TMJ Dynamics 1.5 General Pathology, Inflammation & Immunity Concepts
2 Chapter 2: Oral Pathology, Microbiology & Biofilm Ecology
2.1 Oral Mucosal Lesions, Soft Tissue & Salivary Pathology 2.2 Hard Tissue Anomalies, Cysts, Neoplasms & Radiographic Pathology 2.3 Periodontal Pathology, Plaque Biofilm Ecology & Microbiology 2.4 Cariology, Demineralization Mechanics & Fluoride Chemistry 2.5 Systemic Disease Manifestations & Oral Cancer Risk Factors 2.6 Genetic Conditions, Immunopathology & Diagnostic Biopsy Protocols
3 Chapter 3: Dental Pharmacology, Biochemistry & Nutrition
3.1 Autonomic Drugs, Cardiovascular & Respiratory Pharmacology 3.2 Analgesics, Opioids, NSAIDs & Central Nervous System Agents 3.3 Antimicrobial Therapy, Antibiotic Prophylaxis & Antivirals/Antifungals 3.4 Nutritional Biochemistry, Vitamins, Minerals & Dietary Analysis 3.5 Endocrine Pharmacology, Diabetic Care & Bone Metabolism Agents 3.6 Special Population Pharmacotherapeutics & Drug Interactions
4 Chapter 4: Patient Assessment, Risk Evaluation & Radiographic Interpretation
4.1 Health History Review, ASA Physical Status & Medical Risk Assessment 4.2 Comprehensive Extraoral/Intraoral Examination & Soft Tissue Inspection 4.3 Periodontal Assessment, Probing Techniques & Furcation Classification 4.4 Hard Tissue Examination, Caries Detection & Restorative Evaluation 4.5 Dental Radiography Principles, Physics, Technique & Radiation Safety 4.6 Radiographic Interpretation, Normal Landmarks & Pathologic Artifacts
5 Chapter 5: Periodontal Therapy, Instrumentation & Preventive Services
5.1 Periodontal Disease Etiology, Pathogenesis & Host Response 5.2 Non-Surgical Periodontal Therapy (NSPT) & Scaling/Root Planing (SRP) 5.3 Dental Hygiene Instrumentation, Ergonomics & Sharpness Maintenance 5.4 Preventive Oral Health Agents, Dentifrices, Rinses & Remineralization 5.5 Surgical Periodontal Therapy Overview & Maintenance Protocols 5.6 Patient Motivation, Behavioral Change & Oral Hygiene Instruction 5.7 Care Planning for Special Needs, Medically Compromised & Geriatric Patients
6 Chapter 6: Local Anesthesia Administration, Dental Materials & Special Care
6.1 Local Anesthesia Pharmacology, Neurophysiology & Vasoconstrictors 6.2 Injection Techniques, Anatomical Landmarks & Nerve Blocks 6.3 Local Anesthesia Complications, Toxicity & Nitrous Oxide Sedation 6.4 Dental Materials Chemistry, Impression Media & Restorative Auxiliaries 6.5 Pit & Fissure Sealants, Polishers & Biomaterial Biocompatibility 6.6 Orthodontic, Endodontic, Pediatric & Implant Patient Care
7 Chapter 7: Infection Prevention, OSHA/CDC Protocols & Medical Emergencies
7.1 Infection Control Principles, Transmission Pathways & Standard Precautions 7.2 Sterilization Methods, Biological Monitoring & Chemical Disinfection 7.3 OSHA Bloodborne Pathogens Standard, HazCom & Regulatory Compliance 7.4 Medical Emergency Recognition, CPR/AED & Protocol Management 7.5 Pharmacological Emergency Interventions & Airway Management 7.6 Instrument Processing Safety, Waste Management & Post-Exposure Protocols
8 Chapter 8: Community Oral Health, Epidemiology & Evidence-Based Research
8.1 Dental Public Health Principles, Community Assessment & Needs Analysis 8.2 Oral Epidemiology Indices: DMF, GI, PI, CPITN, Debris & Calculus Indices 8.3 Community Water Fluoridation Standards, Cost-Benefit & Public Health Policy 8.4 Evidence-Based Decision Making, Research Design, Control Groups & Sampling 8.5 Biostatistics in Dental Research: Mean, Median, P-values, Sensitivity & Specificity
9 Chapter 9: Integrated Case-Based Scenarios, Patient Cases & Professional Ethics
9.1 Case Scenario 1: Complex Periodontal Patient with Systemic Conditions 9.2 Case Scenario 2: Pediatric & Adolescent Preventive Management 9.3 Case Scenario 3: Medically Compromised & Special Needs Geriatric Patient 9.4 Case Scenario 4: Oral Pathology Identification & Interprofessional Referral 9.5 Professional Ethics, Jurisprudence & Dental Hygiene Practice Acts 9.6 Risk Management, Informed Consent & Interprofessional Collaboration
2.2 Hard Tissue Anomalies, Cysts, Neoplasms & Radiographic Pathology
Key Takeaways Explain This Topic AI
Gemination results in a single root, single canal, and a notched crown with a normal total tooth count; Fusion results in two separate roots/canals and one less than the normal tooth count.
Dens in dente (dens invaginatus) most commonly affects the maxillary lateral incisor, presenting radiographically as a 'tooth within a tooth' with a deep invaginated lingual pit prone to early pulpal necrosis.
A dentigerous cyst (follicular cyst) is an odontogenic cyst attached at the cementoenamel junction (CEJ) surrounding the crown of an unerupted or impacted tooth.
Ameloblastoma is a benign but locally aggressive odontogenic tumor featuring a multilocular 'soap-bubble' or 'honeycomb' radiolucency in the posterior mandible with high recurrence rates.
Symmetrical widening of the periodontal ligament (PDL) space is an early radiographic sign of osteosarcoma of the jaw, which later develops a classic 'sunburst' periosteal appearance.
Last updated: July 2026
2.2 Hard Tissue Anomalies, Cysts, Neoplasms & Radiographic Pathology
NBDHE Core Knowledge: A comprehensive understanding of tooth developmental anomalies, jaw cysts, odontogenic neoplasms, and bone pathology is essential for accurate radiographic interpretation, differential diagnosis, and patient care planning.
1. Developmental Hard Tissue Anomalies
Developmental anomalies of teeth arise during initiation, proliferation, histodifferentiation, morphodifferentiation, or apposition stages of odontogenesis.
Abnormalities in Tooth Size & Number
Microdontia: Teeth that are physically smaller than normal. True generalized microdontia occurs in pituitary dwarfism. Localized microdontia affects individual teeth, most commonly the maxillary lateral incisor ("peg lateral") and maxillary third molars.
Macrodontia: Teeth that are physically larger than normal. True generalized macrodontia occurs in pituitary gigantism.
Anodontia: Complete absence of all primary and permanent teeth. Rare condition strongly linked to hereditary ectodermal dysplasia.
Hypodontia & Oligodontia: Hypodontia is the developmental absence of one to five teeth; oligodontia is the absence of six or more teeth (excluding third molars). Most commonly missing teeth in order of frequency: third molars , mandibular second premolars , and maxillary lateral incisors .
Hyperdontia (Supernumerary Teeth): Presence of extra teeth resulting from cleavage of the dental lamina. The most common supernumerary tooth is the mesiodens , a small peg-shaped tooth located between the maxillary central incisors at the midline. The second most common is the distomolar (fourth molar) located distal to the third molar.
Anomalies in Morphodifferentiation & Shape
Gemination: Developmental anomaly where a single tooth germ attempts to divide, resulting in a tooth with a single root, single root canal , and a large bifid crown featuring a notch on its incisal edge. Clinical Rule: When counting teeth, gemination results in a normal total tooth count .
Fusion: Developmental anomaly resulting from the union of two normally separate adjacent tooth germs at the enamel and dentin levels. Results in a large crown with two separate roots and two root canals . Clinical Rule: When counting teeth, fusion results in one less than the normal tooth count (unless fusing with a supernumerary tooth).
Concresence: A form of fusion in which two fully formed adjacent teeth are united along their root surfaces exclusively by cementum . Most frequently observed between maxillary second and third molars.
Dilaceration: An abnormal, sharp bend or curve in the root or crown of a tooth, caused by trauma or mechanical displacement of the calcified portion of the tooth germ during root development. Poses severe challenges during endodontic therapy and tooth extraction.
Dens in Dente (Dens Invaginatus): A developmental anomaly caused by the invagination of the enamel organ into the dental papilla prior to calcification. Radiographically presents as a "tooth within a tooth" appearance, most commonly affecting the maxillary lateral incisor . The deep invaginated lingual pit communicates directly with the pulp, predisposing the tooth to early pulpal necrosis and periapical pathology without obvious coronal caries.
Dens Evaginatus & Talon Cusp: Dens evaginatus is an accessory enamel cusp projecting from the occlusal surface of premolars (most common in Asian populations). A talon cusp is an accessory cusp located on the lingual surface of maxillary or mandibular incisors, containing a extension of pulp tissue susceptible to exposure during routine occlusal adjustment.
Taurodontism: A developmental anomaly characterized by an elongated body, enlarged pulp chamber, and apically displaced furcation, giving the tooth a "bull-like" appearance. Associated with Down syndrome, Klinefelter syndrome, and ectodermal dysplasia.
Hypercementosis: Excessive deposition of secondary cementum along the root surface. Radiographically appears as a bulbous enlargement of the root surrounded by a continuous intact periodontal ligament (PDL) space and lamina dura. Associated with Paget disease of bone and chronic occlusal trauma.
2. Odontogenic & Non-Odontogenic Cysts
A cyst is defined as a pathological fluid-filled or semi-fluid-filled cavity lined by epithelium and surrounded by a connective tissue capsule. Cysts of the jaws are broadly categorized as odontogenic (derived from tooth-forming epithelium) or non-odontogenic.
Inflammatory & Developmental Odontogenic Cysts
Cyst Entity Radiographic Appearance Anatomical Location & Tissue Origin Key Clinical Features
Radicular Cyst (Periapical Cyst) Well-circumscribed unilocular radiolucency at root apex Apex of a non-vital tooth ; derived from Rests of Malassez Most common jaw cyst (~70%); secondary to pulpal necrosis
Residual Cyst Well-circumscribed radiolucency in an edentulous area Site of a previously extracted tooth Occurs when a radicular cyst is incompletely curetted
Dentigerous Cyst (Follicular Cyst) Well-circumscribed radiolucency attached at CEJ surrounding crown Crown of an unerupted or impacted tooth ; reduced enamel epithelium 2nd most common cyst; most common around impacted 3rd molars and canines
Primordial Cyst Well-circumscribed radiolucency in place of a missing tooth Site where a tooth failed to develop; derived from stellate reticulum Most common in mandibular 3rd molar area
Odontogenic Keratocyst (OKC) Multilocular or unilocular radiolucency with smooth scolloped borders Posterior mandible ramus; derived from dental lamina High recurrence rate (~30%); thin parakeratinized epithelium; link to Gorlin Syndrome
Lateral Periodontal Cyst Small, teardrop unilocular radiolucency between roots Lateral root surface of vital teeth ; mandibular canine/premolar area Tooth remains vital; derived from dental lamina rests
Gingival Cyst of Adult Soft tissue swelling without bone involvement Attachment gingiva of canine/premolar region Soft tissue counterpart of lateral periodontal cyst
Non-Odontogenic & Pseudocysts
Nasopalatine Duct Cyst (Incisive Canal Cyst): The most common non-odontogenic cyst of the oral cavity. Radiographically appears as a characteristic heart-shaped or oval radiolucency located between the apices of the maxillary central incisors at the midline. Caused by epithelial remnants of the nasopalatine duct. Teeth remain vital.
Globulomaxillary Cyst: An anatomical description of a pear-shaped radiolucency located between the roots of the maxillary lateral incisor and canine, causing root divergence. Previously thought to be a developmental fissural cyst, most are now classified as lateral periodontal cysts, radicular cysts, or OKCs.
Stafne Defect (Static Bone Cyst / Lingual Mandibular Salivary Gland Depression): A pseudocyst (lacks an epithelial lining). Radiographically presents as a well-circumscribed, oval radiolucency located below the inferior alveolar nerve canal near the angle of the mandible. Caused by a focal concavity on the lingual cortex accommodating the submandibular salivary gland. Always asymptomatic and requires no treatment.
Traumatic Bone Cyst (Simple Bone Cyst / Solitary Bone Cyst): A pseudocyst presenting radiographically as a well-demarcated radiolucency with characteristic scalloping up between the roots of mandibular teeth. Surgical exploration reveals an empty, air-filled bony cavity without an epithelial lining. Teeth remain vital.
- 3. Benign & Malignant Odontogenic & Bone Neoplasms
- Benign Odontogenic Tumors
Ameloblastoma: The most common clinically significant odontogenic neoplasm. Arises from dental lamina remnants, enamel organ, or dentigerous cyst linings. Radiographically features a characteristic multilocular "soap-bubble" or "honeycomb" radiolucency , most frequently in the posterior mandible and ramus region. Causes cortical expansion, severe tooth displacement, and root resorption. Locally aggressive with a high recurrence rate if managed by curettage alone; requires wide surgical resection.
Odontoma: The most common odontogenic tumor overall (considered a hamartoma rather than a true neoplasm). Composed of mature enamel, dentin, cementum, and pulp tissue.
Compound Odontoma: Composed of multiple small, tooth-like structures (denticles) surrounded by a radiolucent halo. Most commonly located in the anterior maxilla .
Complex Odontoma: Composed of a disorganized, irregular mass of hard dental tissues that bears no anatomical resemblance to teeth. Most commonly located in the posterior mandible .
Cementoblastoma (True Cementoma): A benign neoplasm of cementoblasts. Radiographically presents as a dense, well-defined radiopaque mass attached directly to the root apex of a tooth, surrounded by a thin radiolucent halo. Causes root resorption and fusion with the root. The associated tooth is vital but painful.
Odontogenic Myxoma: A benign gelatinous tumor derived from embryonic dental papilla mesenchymal tissue. Radiographically presents as a multilocular radiolucency with thin, straight trabeculae creating a "tennis racket" or "stepladder" pattern in the posterior mandible.
Bone Neoplasms & Systemic Bone Pathology
Osteosarcoma: The most common primary malignant bone tumor of the jaws. Occurs most frequently in young adults (~30 years old). Early radiographic sign is a symmetrical widening of the periodontal ligament (PDL) space around involved teeth. Advanced cases exhibit a characteristic "sunburst" pattern caused by delicate spicules of malignant bone projecting outward beneath the elevated periosteum.
Paget Disease of Bone (Osteitis Deformans): A chronic metabolic bone disorder characterized by uncoordinated osteoclast-mediated bone resorption followed by disorganized osteoblast-mediated bone deposition. Most common in older males. Radiographically exhibits a "cotton-wool" appearance of the skull and jaws in late stages. Causes hypercementosis of roots, expansion of the maxilla ("hat size increases"), and elevated serum alkaline phosphatase levels.
Central Cemento-Osseous Dysplasia (COD): Benign fibro-osseous lesions occurring in the periapical regions of anterior mandibular teeth, overwhelmingly affecting middle-aged Black females. Affected teeth are vital . Radiographically progresses from early radiolucent stages to mixed and late radiopaque stages surrounded by a radiolucent halo. Requires no treatment; biopsy is contraindicated due to risk of osteomyelitis.