MDCG Dental Exam cheat sheet

Trigeminal nerve (CN V) has three divisions: V1 ophthalmic (superior orbital fissure), V2 maxillary (foramen rotundum), V3 mandibular (foramen ovale); V3 is the only division carrying motor fibers to muscles of mastication.

Facial nerve (CN VII) exits the skull via the stylomastoid foramen; branches within the parotid gland are temporal, zygomatic, buccal, marginal mandibular, and cervical (TZBMC).

The mandibular foramen lies on the medial surface of the ramus, its position roughly at the level of the occlusal plane in adults; inferior alveolar nerve block targets just above and behind the lingula.

Lingual nerve lies anterior and medial to the inferior alveolar nerve in the pterygomandibular space; it carries chorda tympani fibers for taste from the anterior two-thirds of the tongue.

The maxillary artery's third part gives the middle meningeal, inferior alveolar, and buccal arteries; the inferior alveolar artery enters the mandibular foramen with the nerve.

Muscles of mastication (masseter, temporalis, medial pterygoid, lateral pterygoid) are all supplied by V3; the lateral pterygoid opens and protrudes the mandible, while the other three elevate it.

The pterygoid venous plexus communicates with the cavernous sinus through emissary veins; this is the anatomical basis for spread of dental infection to intracranial sites.

The temporomandibular joint is a bilateral synovial joint with a fibrocartilaginous disc; the lower compartment performs rotation and the upper compartment performs translation during opening.

The carotid triangle is bounded by the posterior belly of digastric, superior belly of omohyoid, and anterior border of sternocleidomastoid; it contains the carotid bifurcation and internal jugular vein.

Enamel is 96% mineral by weight, formed by ameloblasts, and is acellular and incapable of regeneration; its structural units are rods (prisms) and interrod enamel.

Dentin is about 70% mineral, 20% organic (mostly type I collagen), and 10% water; it is formed by odontoblasts that retreat pulpally, leaving dentinal tubules.

Cementum is avascular and about 45-50% mineral; acellular extrinsic fiber cementum covers the cervical third and provides attachment of principal fibers.

The dental lamina appears at about 6 weeks in utero; the bud stage occurs around 8 weeks, cap stage at 9-10 weeks, and bell stage at 11-12 weeks.

The reduced enamel epithelium and oral epithelium fuse to form the dentogingival junction; the junctional epithelium attaches via hemidesmosomes and internal basal lamina.

Permanent tooth eruption times: first molar 6 years, central incisor 7, lateral incisor 8, first premolar 10, second premolar 11, canine 11-12, second molar 12.

Primary teeth erupt from about 6 months (mandibular central incisor) to 24-30 months (second molars); the primary dentition comprises 20 teeth.

The pulp contains odontoblasts, fibroblasts, undifferentiated mesenchymal cells, and the subodontoblastic cell-free and cell-rich zones (Weil and Höhl layers).

Salivary glands: parotid is serous, submandibular is mixed predominantly serous, sublingual is mixed predominantly mucous; minor glands are mostly mucous except von Ebner glands.

Leukoplakia is a clinical diagnosis of a white patch that cannot be characterized as any other disease; dysplasia is confirmed only histologically, and the risk of malignant transformation increases with dysplasia grade.

Erythroplakia has a much higher malignant transformation rate than leukoplakia and should be biopsied promptly.

Squamous cell carcinoma of the lip most commonly affects the lower lip at the vermilion border; the tongue lateral border is the most common intraoral site.

Ameloblastoma is a locally aggressive odontogenic tumor of the posterior mandible, often multilocular 'soap bubble' radiolucency; treatment is resection with margins.

Odontoma is the most common odontogenic tumor; compound type shows tooth-like structures, complex type shows disordered dental hard tissue.

Dentigerous cyst encloses the crown of an unerupted tooth and attaches at the CEJ; it is the most common developmental odontogenic cyst.

Radicular cyst is inflammatory, arises from epithelial rests of Malassez at the apex of a non-vital tooth, and is the most common odontogenic cyst overall.

Recurrent aphthous stomatitis presents as painful, recurrent, round ulcers with a yellow fibrinous base and erythematous halo; minor aphthae heal in 7-14 days without scarring.

Oral lichen planus shows Wickham striae, a band-like lymphocytic infiltrate, and basal cell liquefaction degeneration; it carries a small malignant transformation risk and is managed as a chronic condition.

Periapical radiograph findings: widened PDL, loss of lamina dura, and periapical radiolucency indicate apical periodontitis; a sinus tract indicates a chronic apical abscess.

Streptococcus mutans is the principal cariogenic organism; it produces glucosyltransferases that synthesize insoluble glucans and adheres to the pellicle.

Lactobacillus species are associated with progression of existing carious lesions rather than initiation.

Porphyromonas gingivalis, Tannerella forsythia, and Treponema denticola form the 'red complex' associated with periodontitis.

Aggregatibacter actinomycetemcomitans is associated with aggressive (stage III/IV grade C) periodontitis and produces leukotoxin.

Dental unit waterlines must meet ≤500 CFU/mL heterotrophic bacteria; flushing and independent water reservoirs or filters are used to control biofilm.

Sterilization by autoclave is validated with biological indicators (Geobacillus stearothermophilus spores) and chemical indicators for each load.

Spore-forming organisms such as Bacillus and Clostridium are the reference challenge for sterilization; prions are not reliably inactivated by standard autoclave cycles.

Standard precautions apply to all patients regardless of diagnosis; gloves, masks, eye protection, and hand hygiene are minimum requirements.

Hepatitis B is the most transmissible bloodborne pathogen percutaneous exposure (risk up to 30% from a needlestick with HBeAg-positive blood); hepatitis C is about 3% and HIV about 0.3%.

Immunoglobulins: IgA is the predominant secretory antibody in saliva, IgG dominates in gingival crevicular fluid during inflammation, and IgE mediates type I hypersensitivity.

Lidocaine 2% with 1:100,000 epinephrine: maximum recommended dose is 7 mg/kg (4.4 mg/kg for a 70 kg adult ≈ 300 mg; about 8 cartridges of 1.8 mL).

Articaine 4% with 1:100,000 epinephrine: maximum dose 7 mg/kg; 1.8 mL cartridge contains 72 mg articaine.

Mepivacaine 3% plain maximum dose is 6.6 mg/kg; bupivacaine 0.5% with 1:200,000 epinephrine provides the longest duration (up to 8-12 hours pulpal).

Epinephrine limit in a healthy patient is about 0.2 mg per appointment; a 1:100,000 cartridge of 1.8 mL contains 0.018 mg epinephrine.

Amoxicillin is the first-line antibiotic for odontogenic infection; dose 500 mg every 8 hours or 875 mg every 12 hours; penicillin allergy alternatives are clindamycin, azithromycin, or cephalexin (with caution).

Antibiotics are adjuncts to drainage and source control; they are not indicated for localized, self-limiting infections without systemic involvement.

NSAIDs such as ibuprofen inhibit COX-1 and COX-2; aspirin irreversibly acetylates platelet COX-1, and bleeding risk persists 7-10 days after stopping.

Paracetamol (acetaminophen) overdose causes hepatic necrosis through the NAPQI metabolite; N-acetylcysteine is the antidote.

Chlorhexidine 0.12-0.2% is a cationic bisbiguanide; it binds to oral tissues with substantivity of about 12 hours and can cause staining and taste alteration.

Fluoride varnish (5% NaF, 22,600 ppm) is applied to caries-active surfaces; systemic fluoride supplements are indicated only when water fluoride is deficient.

Root canal working length is typically 0.5-1.0 mm short of the radiographic apex; the apical constriction is the reference point for obturation.

The apical foramen is usually located 0.5-1.0 mm from the anatomic apex and often deviates from the long axis of the root.

Sodium hypochlorite (0.5-5.25%) dissolves organic tissue and is antimicrobial; EDTA (17%) removes the smear layer and chelates calcium.

Irrigant extrusion beyond the apex risks tissue necrosis and nerve injury; the needle should be loose-fitting and not wedged in the canal.

C-shaped canals are most common in mandibular second molars; the mesiobuccal root of the maxillary first molar frequently has two canals (MB1 and MB2).

Rubber dam isolation is the standard for endodontic treatment and is required for adhesive dentistry to control moisture.

Cementoenamel junction is the key landmark for restoration margins and endodontic access; enamel is thicker at cusps and thinnest at the cervical margin.

Composite resin bonding to enamel relies on acid etching (37% phosphoric acid) creating microporosity; dentin bonding uses etch-and-rinse or self-etch systems.

Posterior teeth with large MOD restorations are at risk of cusp fracture; cuspal coverage (onlay or crown) is indicated when remaining walls are thin.

Gingivitis is reversible inflammation confined to the gingiva; periodontitis involves attachment loss and alveolar bone loss.

Probing depth is measured from the gingival margin to the base of the sulcus; clinical attachment level is measured from the CEJ to the base of the sulcus.

Bleeding on probing has high sensitivity but low specificity for disease progression; absence of bleeding on probing has high negative predictive value for stability.

Periodontal staging (2018 classification): Stage I/II early/moderate, Stage III/IV advanced with tooth loss and complexity factors; grading (A, B, C) reflects rate of progression.

Non-surgical periodontal therapy (scaling and root planing) is the first-line treatment; re-evaluation occurs at 6-8 weeks before surgical decisions.

Furcation involvement is classified Glickman I-IV; grade IV indicates through-and-through involvement with gingival recession.

Aggressive periodontitis (now stage III/IV grade C) often presents with molar-incisor pattern in young patients and familial aggregation.

Risk factors for periodontitis include smoking, poorly controlled diabetes (HbA1c >7%), and genetic predisposition; smoking reduces bleeding and masks inflammation.

Peri-implant mucositis is reversible inflammation of soft tissue around an implant; peri-implantitis involves bone loss and is not fully reversible.

Inferior alveolar nerve block landmarks: coronoid notch, pterygomandibular raphe, and occlusal plane; target is 6-10 mm above the occlusal plane, 1 mm above the lingula.

Positive aspiration rates are highest with the inferior alveolar nerve block (10-15%); aspirate in two planes before injecting.

Extraction of a mandibular third molar risks injury to the inferior alveolar nerve and lingual nerve; cone-beam CT is indicated when roots are close to the canal.

Dry socket (alveolar osteitis) presents 2-4 days post-extraction with severe pain and an empty socket; management is irrigation and a medicated dressing.

Ludwig's angina is a bilateral submandibular, submental, and sublingual cellulitis; it is a surgical emergency requiring airway assessment and incision and drainage.

Maxillary sinus communication after extraction is managed by avoiding nose-blowing and may require primary closure; a large defect needs a flap.

Local anesthetic maximum doses: lidocaine 7 mg/kg with epinephrine, 4.4 mg/kg plain; bupivacaine 1.3 mg/kg with epinephrine.

Syncope is the most common medical emergency in dental practice; management is supine position with legs elevated and airway monitoring.

Malignant hyperthermia is triggered by succinylcholine and volatile anesthetics; dantrolene is the specific treatment.

Class I molar relationship: mesiobuccal cusp of maxillary first molar occludes in the buccal groove of the mandibular first molar.

Class II molar relationship: mesiobuccal cusp of maxillary first molar occludes mesial to the buccal groove; Class III occludes distal to the groove.

Angle's classification is based on the first permanent molars; canine relationship and incisor relationship are also recorded.

Cephalometric landmarks: Sella, Nasion, A-point, B-point; ANB angle indicates skeletal Class II (ANB >4°) or Class III (ANB <0°).

The leeway space is the difference in mesiodistal width between primary canines and molars and their permanent successors; it is about 1.5 mm per side in the mandible.

Eruption of the first permanent molar at age 6 is the key event for occlusal development; space maintenance is indicated when primary teeth are lost early.

Fluoride toothpaste concentration: 1,000-1,500 ppm for children, 2,800-5,000 ppm for high caries risk; a smear or pea-sized amount is used for young children.

Pulpotomy is indicated for a vital pulp with coronal inflammation; pulpectomy is indicated when radicular pulp is involved.

Hand-over-mouth and papoose board are restrictive techniques requiring informed consent and documentation; tell-show-do is the first-line behavior guidance method.

Complete denture retention depends on adhesion, cohesion, surface tension, and atmospheric pressure; the post dam improves the posterior seal.

The neutral zone is the space where forces from the tongue, lips, and cheeks are balanced; teeth are positioned there in complete dentures.

Balanced occlusion in complete dentures requires bilateral simultaneous contacts in centric and eccentric positions to prevent tipping.

The curve of Spee and curve of Wilson are incorporated in denture tooth arrangement; the compensating curve helps maintain balanced occlusion.

Fixed partial denture abutment selection requires an anticlastic curve; a minimum of two abutments is needed, and the span should not exceed two pontics in most cases.

Ferrule effect: at least 1.5-2 mm of circumferential dentin above the crown margin improves resistance to fracture of endodontically treated teeth.

Implant success criteria include less than 0.2 mm annual bone loss after the first year, no mobility, and no peri-implant radiolucency.

Occlusal vertical dimension is assessed by freeway space (2-4 mm) and facial proportions; loss of vertical dimension can cause angular cheilitis.

Abutment preparation taper should be 6-10 degrees for optimal retention and resistance form.

Bitewing radiographs show crowns and alveolar crests; they are indicated for caries detection and crestal bone assessment.

Periapical radiographs show the entire tooth and periapical tissues; the paralleling technique reduces distortion compared with bisecting-angle technique.

Panoramic radiograph is a tomographic image with about 20-30% magnification; it is a screening tool, not a substitute for intraoral images.

Cone-beam CT provides three-dimensional imaging with lower dose than medical CT; it is indicated for implant planning, impacted teeth, and complex endodontics.

The ALARA principle (as low as reasonably achievable) governs dose optimization; collimation, filtration, and digital sensors reduce patient dose.

Radiolucent structures: enamel is the most radiopaque dental tissue, followed by dentin, cementum, and pulp (least radiopaque).

A radiolucency at the apex with loss of lamina dura suggests periapical pathology; a well-defined corticated radiolucency suggests a cyst.

Caries appears as a radiolucent area; occlusal caries is often underestimated on radiographs and requires clinical examination.

Anatomic landmarks on panoramic radiographs: mandibular canal, mental foramen, maxillary sinus, and nasal fossa; the ghost image of the opposite side appears above the contralateral ramus.

Informed consent requires disclosure of diagnosis, proposed treatment, alternatives, risks, and consequences; it must be documented and obtained before treatment.

The four principles of biomedical ethics are autonomy, beneficence, non-maleficence, and justice.

Confidentiality is a legal and ethical duty; disclosure is permitted with patient consent, legal requirement, or public health exception.

Mandatory reporting obligations vary by jurisdiction; suspected child abuse or neglect is reportable in most jurisdictions.

Negligence requires four elements: duty of care, breach of duty, causation, and damages.

Record retention requirements vary by jurisdiction; a common minimum is 7 years after last treatment, and longer for minors (until age of majority plus a period).

Scope of practice is defined by licensure; delegating procedures to unlicensed personnel is prohibited.

Fee splitting and kickbacks are generally prohibited; advertising must be truthful and not misleading.

Risk management includes thorough documentation, informed consent, and clear communication; adverse events should be disclosed to the patient.