National Board Dental Examination / Integrated National Board Dental Examination (INBDE) Foundational Biomedical Sciences Syllabus

Which cranial nerve provides taste to the anterior two-thirds of the tongue, and via which branch?

The facial nerve (CN VII) via the chorda tympani branch; general sensation to that area is via the lingual nerve (CN V3).

What is the blood supply to the maxillary and mandibular teeth?

Maxillary teeth: posterior, middle, and anterior superior alveolar arteries (branches of the maxillary artery); mandibular teeth: inferior alveolar artery (branch of the maxillary artery).

From which artery does the maxillary artery arise, and why is it clinically important in dentistry?

It arises from the external carotid artery; it supplies the deep face, teeth, and nasal cavity, and its branches (e.g., inferior alveolar, posterior superior alveolar) are relevant during anesthesia and surgery.

Which lymph nodes drain most of the oral cavity, and where does drainage ultimately converge?

Submental, submandibular, and deep cervical (jugulodigastric) nodes drain the oral cavity; all eventually drain into the deep cervical chain along the internal jugular vein and then the jugular lymphatic trunk.

Why is the danger triangle of the face clinically significant for infection spread?

Veins of the face (from corner of mouth to nose bridge) communicate with the cavernous sinus via the ophthalmic veins without valves, so infection can spread intracranially causing cavernous sinus thrombosis.

A maxillary canine infection that perforates above the muscle attachment can spread to which space, causing periorbital swelling?

The canine space (infraorbital), which can lead to swelling near the eye and potentially cavernous sinus thrombosis if it tracks via the angular vein.

Which fascial space is involved when a mandibular molar infection perforates lingual to the mylohyoid line, and what is the airway risk?

The submandibular space (below mylohyoid); bilateral involvement of submandibular, sublingual, and submental spaces is Ludwig's angina, a life-threatening airway emergency.

Determine whether a mandibular molar abscess drains to the sublingual or submandibular space based on apex position relative to the mylohyoid line.

Apices above (superior to) the mylohyoid line drain to the sublingual space; apices below it (e.g., second and third molars) drain to the submandibular space.

From which embryologic structures do the primary and secondary palate develop?

The primary palate forms from the median palatine process (intermaxillary segment) of the medial nasal prominences; the secondary palate forms from the lateral palatine shelves of the maxillary prominences that fuse in the midline.

What is the embryologic basis of a cleft lip versus a cleft palate?

Cleft lip results from failure of fusion of the maxillary prominence with the medial nasal prominence; cleft palate results from failure of fusion of the palatine shelves with each other or with the primary palate/nasal septum.

Name the stages of tooth development in order.

Bud stage, cap stage, bell stage, then apposition and maturation (crown formation), followed by root formation and eruption.

What is reciprocal induction in odontogenesis, and which two tissues are involved?

The mutual signaling between oral ectoderm-derived dental epithelium (enamel organ) and neural crest-derived ectomesenchyme (dental papilla), which directs differentiation of ameloblasts and odontoblasts.

Which cells form enamel and which form dentin, and from which embryonic origin does each arise?

Ameloblasts (ectoderm/enamel organ) form enamel; odontoblasts (neural crest ectomesenchyme/dental papilla) form dentin.

Compare the mineral content of enamel, dentin, and cementum by weight.

Enamel is ~96% mineral (hardest), dentin ~70% mineral, and cementum ~45-50% mineral; the rest is organic matrix and water.

What are the two main types of dentin produced over time, and what are dentinal tubules?

Primary dentin forms before root completion and secondary dentin forms slowly afterward; dentinal tubules are channels housing odontoblast processes that transmit stimuli, accounting for dentin sensitivity.

What are the four zones of the dental pulp from periphery to center?

Odontoblastic layer, cell-free zone (of Weil), cell-rich zone, and the central pulp core containing vessels and nerves.

Differentiate acellular (primary) from cellular (secondary) cementum.

Acellular cementum covers the cervical root, forms slowly, and anchors Sharpey's fibers; cellular cementum covers the apical root, forms faster, contains cementocytes, and adapts to functional demands.

Describe the principal fiber groups of the periodontal ligament and their function.

Alveolar crest, horizontal, oblique (most numerous, resist axial forces), apical, and interradicular fibers; collectively they suspend the tooth and convert occlusal forces into tension on alveolar bone.

What are Sharpey's fibers in the context of the periodontium?

The terminal ends of periodontal ligament collagen fibers embedded into both the cementum and the alveolar bone, anchoring the tooth in its socket.

Differentiate the three types of oral mucosa by location and keratinization.

Masticatory mucosa (gingiva, hard palate) is keratinized; lining mucosa (cheeks, floor of mouth, soft palate) is non-keratinized; specialized mucosa (dorsum of tongue) bears taste papillae.

Compare the three major salivary glands by secretion type.

Parotid is purely serous, submandibular is mixed (predominantly serous), and sublingual is mixed (predominantly mucous).

Describe the phases of the cardiac action potential in ventricular myocytes.

Phase 0 rapid depolarization (Na+ influx), phase 1 early repolarization, phase 2 plateau (Ca2+ influx balancing K+ efflux), phase 3 repolarization (K+ efflux), phase 4 resting potential.

What events occur at the neuromuscular junction to trigger muscle contraction?

Acetylcholine released from the motor neuron binds nicotinic receptors on the motor end plate, depolarizing it; this triggers an action potential, Ca2+ release from the sarcoplasmic reticulum, and actin-myosin cross-bridge cycling.

State the equation relating cardiac output, heart rate, and stroke volume.

Cardiac output (CO) = heart rate (HR) × stroke volume (SV).

Define tidal volume, residual volume, and vital capacity.

Tidal volume is air moved in a normal breath; residual volume is air remaining after maximal expiration; vital capacity is the maximum air exhaled after maximal inhalation (TV + IRV + ERV).

How do the kidneys regulate blood pressure via the renin-angiotensin-aldosterone system?

Low perfusion triggers renin release, converting angiotensinogen to angiotensin I; ACE converts it to angiotensin II (vasoconstriction), which stimulates aldosterone to increase Na+/water reabsorption, raising blood pressure.

Which bacteria are most associated with dental caries and periodontal disease respectively?

Caries: Streptococcus mutans (and Lactobacillus) which produce acid from sugars; chronic periodontitis: Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola (the 'red complex').

Describe the four stages of dental biofilm (plaque) formation.

1) Acquired pellicle formation (salivary glycoproteins), 2) initial reversible bacterial adhesion (early colonizers like streptococci), 3) coaggregation/maturation, 4) formation of a structured mature biofilm with a matrix.

Distinguish the virology of HSV-1 from the fungal organism causing oral candidiasis.

HSV-1 is a DNA herpesvirus causing recurrent herpes labialis/gingivostomatitis that remains latent in the trigeminal ganglion; Candida albicans is a fungus (yeast) causing pseudomembranous candidiasis (thrush), an opportunistic infection.

Differentiate sterilization, disinfection, and antisepsis, and name the most common dental sterilization method.

Sterilization kills all microbes including spores (e.g., steam autoclave at 121°C/15 psi); disinfection kills most pathogens on inanimate surfaces but not all spores; antisepsis reduces microbes on living tissue. The autoclave is the standard dental sterilizer.