- Universal tooth numbering system
- The U.S. standard: permanent teeth are numbered 1–32, starting at the maxillary right third molar (1) and ending at the mandibular right third molar (32).
- Tooth #1 in the Universal system
- The maxillary right third molar (upper-right wisdom tooth) — numbering begins here.
- Tooth #8 and #9
- The two maxillary central incisors — #8 is the right central, #9 is the left central.
- How many permanent (adult) teeth?
- 32 permanent teeth: 8 incisors, 4 canines, 8 premolars, and 12 molars (including third molars).
- How many primary (baby) teeth?
- 20 primary teeth. In the Universal system they are lettered A through T.
- Four types of teeth and their jobs
- Incisors (cut), canines/cuspids (tear), premolars/bicuspids (crush), molars (grind).
- Mesial surface
- The tooth surface toward the midline of the arch (toward the front centerline).
- Distal surface
- The tooth surface away from the midline (toward the back of the arch).
- Facial surface
- The surface toward the cheek or lip — called buccal on posterior teeth and labial on anterior teeth.
- Lingual surface
- The tooth surface facing the tongue.
- Occlusal surface
- The chewing surface of posterior teeth (premolars and molars).
- Incisal edge
- The biting edge of anterior teeth (incisors and canines).
- Palmer notation system
- Divides the mouth into four quadrants with a bracket symbol; permanent teeth are 1–8 per quadrant from the midline back.
- FDI (international) numbering
- A two-digit system: the first digit is the quadrant (1–4 permanent), the second is the tooth (1–8 from midline).
- Anterior teeth
- The front teeth: incisors and canines.
- Posterior teeth
- The back teeth: premolars and molars.
- Maxillary arch vs mandibular arch
- Maxillary = the upper jaw (fixed to the skull); mandibular = the lower jaw (the movable jaw).
- Angle's Class I malocclusion
- Normal molar relationship (neutrocclusion) but with crowding or other tooth-position problems.
- Angle's Class II malocclusion
- The mandibular (lower) arch is positioned distal (back) to the maxillary — a retruded lower jaw, 'overbite' look.
- Angle's Class III malocclusion
- The mandibular (lower) arch is positioned mesial (forward) to the maxillary — a protruded lower jaw, 'underbite.'
- Four-handed dentistry
- Seated, coordinated team dentistry where the assistant anticipates and passes instruments so the operator never looks away from the field.
- Instrument transfer zone
- The area where instruments are passed — typically near the patient's chin/chest, below the patient's nose, out of sight of the patient's eyes.
- Operating zones (clock concept), right-handed operator
- Operator 7–12 o'clock, assistant 2–4 o'clock, transfer zone 4–7, static (instrument) zone 12–2.
- Normal adult resting pulse rate
- 60–100 beats per minute.
- Normal adult respiration rate
- 12–20 breaths per minute (count discreetly so the patient doesn't alter their breathing).
- Normal adult body temperature
- About 98.6°F (37°C); the febrile (fever) threshold is generally ≥100.4°F (38°C).
- Normal adult blood pressure
- Less than 120/80 mmHg. The top number is systolic (heart contracting); the bottom is diastolic (heart at rest).
- Systolic vs diastolic blood pressure
- Systolic (higher) = pressure when the heart contracts; diastolic (lower) = pressure when the heart rests between beats.
- Why review the medical/dental history?
- To identify conditions, allergies, and medications that affect dental treatment and patient safety before care begins.
- Bisphosphonate medications — dental concern
- They raise the risk of medication-related osteonecrosis of the jaw (MRONJ), especially after extractions or oral surgery.
- Epinephrine in local anesthetic
- A vasoconstrictor added to prolong anesthesia and reduce bleeding by constricting blood vessels at the site.
- Topical anesthetic vs local (injectable) anesthetic
- Topical numbs the surface mucosa before the injection; local/injectable anesthetic blocks the nerve to numb the tooth and tissue.
- Amalgam restorative material
- A silver-colored alloy (silver, tin, copper, mercury) used for posterior fillings; strong and durable.
- Composite resin restorative material
- A tooth-colored filling material that is acid-etched and bonded, then light-cured; used where esthetics matter.
- Acid etch before a composite
- Phosphoric acid (≈37%) is applied to roughen and clean the enamel so the bonding agent and composite mechanically lock on.
- Curing light
- A device that emits visible blue light to polymerize (harden) light-cured composite resin.
- Amalgam carrier
- An instrument used to carry and dispense amalgam into the prepared cavity.
- Amalgam condenser (plugger)
- An instrument used to pack/condense amalgam firmly into the cavity preparation.
- Carver (e.g., discoid-cleoid)
- An instrument used to shape and contour amalgam to anatomy after condensation.
- Burnisher
- A smooth-tipped instrument used to smooth and adapt the margins/surface of an amalgam restoration.
- Tofflemire matrix retainer + band
- Forms a temporary wall for a Class II restoration so material can be packed and properly contoured at the proximal surface.
- Purpose of a wedge
- Placed at the gingival margin to hold the matrix band tight and establish good contact, preventing an overhang.
- Articulating paper
- Marking paper used to identify high spots and check the patient's occlusion (bite) after a restoration.
- Cavity liner/base purpose
- Placed in a deep preparation to protect and insulate the pulp from thermal, chemical, and mechanical irritation.
- Class I cavity (G.V. Black)
- A cavity in the pits and fissures — occlusal surfaces of posterior teeth and lingual pits of anteriors.
- Class II cavity
- A cavity on the proximal (mesial/distal) surfaces of posterior teeth.
- Class III cavity
- A cavity on the proximal surfaces of anterior teeth, not involving the incisal edge.
- Class IV cavity
- A cavity on the proximal surface of an anterior tooth that does involve the incisal edge.
- Class V cavity
- A cavity in the gingival (cervical) third of the facial or lingual surface of any tooth.
- Fixed prosthesis (bridge)
- A non-removable replacement that anchors artificial teeth to natural teeth or implants (abutments).
- Pontic
- The artificial tooth in a fixed bridge that replaces the missing natural tooth.
- Abutment (bridge)
- The natural tooth (or implant) that supports and anchors a fixed bridge.
- Provisional (temporary) crown
- A short-term crown that protects the prepared tooth while the permanent crown is being fabricated in the lab.
- Removable partial denture (RPD)
- A removable appliance that replaces some teeth and is held by metal clasps on remaining natural teeth.
- Complete (full) denture
- A removable appliance that replaces all the teeth in an arch.
- Alginate impression material
- An irreversible hydrocolloid used for study models and preliminary impressions; mixed with water to a paste.
- Endodontics
- The dental specialty treating the dental pulp and root canals (e.g., root canal therapy).
- Pulp
- The soft tissue inside the tooth containing nerves and blood vessels; the 'living' core.
- Periodontics
- The specialty treating the supporting structures of teeth (gingiva, periodontal ligament, alveolar bone).
- Periodontal probing depth
- Measured in millimeters; a healthy sulcus is about 1–3 mm. Greater depths suggest periodontal pocketing.
- Gingival recession
- Apical migration of the gum margin that exposes root surface; recorded with probing depth for attachment level.
- Prophylaxis (prophy)
- A professional dental cleaning to remove plaque, calculus, and stains and prevent disease.
- Calculus (tartar)
- Hardened, mineralized plaque on the teeth that must be removed with instruments (scaling).
- Sealant
- A thin resin coating placed in the pits and fissures of posterior teeth to prevent decay.
- Fluoride — dental benefit
- Strengthens enamel and helps prevent and remineralize early caries.
- Oral evacuation: HVE vs saliva ejector
- The high-volume evacuator (HVE) removes large amounts of fluid/debris and aerosols; the saliva ejector provides low-volume continuous suction.
- Rubber dam — purpose
- Isolates the tooth, keeps the field dry, improves visibility, and protects the patient from debris and aspiration.
- Air-water syringe
- Delivers air, water, or a spray to rinse, dry, and improve visibility of the operating field.
- Explorer
- A thin, sharp-tipped instrument used to detect caries, calculus, and irregularities on tooth surfaces.
- Periodontal probe
- A blunt, millimeter-marked instrument used to measure sulcus/pocket depths around teeth.
- Mouth mirror — three uses
- Indirect vision, retraction of tissue (cheek/tongue), and reflection of light onto the field.
- Cotton pliers
- Locking or non-locking pliers used to carry and place small items like cotton pellets into and out of the mouth.
- Spoon excavator
- A spoon-shaped hand instrument used to remove soft, decayed dentin (caries) from a preparation.
- High-speed handpiece
- A water-cooled handpiece running at very high rpm used to cut enamel and remove decay.
- Low-speed handpiece
- A slower handpiece used for caries removal, polishing, and refining a preparation.
- Cement vs base vs liner
- Liner (thin, protects pulp), base (thicker, insulates/supports), cement (luting agent that bonds restorations like crowns).
- Gingiva
- The gum tissue surrounding and protecting the teeth and alveolar bone.
- Three pairs of major salivary glands
- Parotid, submandibular, and sublingual glands.
- Two main parts of a tooth
- The crown (above the gumline, covered by enamel) and the root (below the gumline, covered by cementum).
- Hardest substance in the body
- Enamel — the highly mineralized outer covering of the tooth crown.
- Dentin
- The bulk of the tooth beneath enamel and cementum; it contains tubules and surrounds the pulp.
- Cementum
- The mineralized tissue covering the root surface; anchors the periodontal ligament fibers.
- Periodontal ligament (PDL)
- Connective tissue fibers that attach the tooth root (cementum) to the alveolar bone.
- Permanent eruption: first tooth
- The first permanent molars (the '6-year molars'), erupting around age 6.
- Medical emergency: syncope (fainting)
- Most common dental office emergency; place the patient supine (or Trendelenburg) and ensure airway and oxygen.
- Why monitor vital signs?
- They establish a baseline and reveal conditions (e.g., hypertension) that influence safe dental treatment.
- Coronal polishing
- Polishing the clinical crowns to remove plaque and stains; it does not remove calculus.
- Documentation rule for charting
- Chart accurately, completely, and contemporaneously; never alter records improperly — the chart is a legal document.
- Congenitally missing tooth — charting
- Charted as missing/absent because it never developed (vs. an extracted tooth, which is marked differently).
- Centric occlusion
- The maximum, habitual intercuspation (bite) when the upper and lower teeth are fully meshed together.
- Overbite vs overjet
- Overbite = vertical overlap of upper over lower anterior teeth; overjet = horizontal projection of upper beyond lower.
- Anesthetic computer-tip aspiration — assistant role
- Have anesthetic ready, ensure aspiration before injection to avoid intravascular delivery, and monitor the patient.
- Mandibular block (IAN) injection
- Anesthetizes the inferior alveolar nerve, numbing the lower teeth, lip, and chin on that side.
- Maxillary infiltration injection
- Deposits anesthetic near the tooth apex; works on upper teeth because the maxillary bone is more porous.
- Quadrant
- One of four sections of the dentition — maxillary right/left and mandibular right/left, divided at the midline.
- Sextant
- One of six sections of the dentition (anterior and posterior segments of each arch).
- Primary teeth lettering (Universal)
- Primary teeth are lettered A–T: A is the maxillary right second molar, T is the mandibular right second molar.
- Number of teeth per arch (permanent)
- 16 teeth per arch — 8 on each side: 2 incisors, 1 canine, 2 premolars, 3 molars.
- Apex of a tooth
- The tip of the root, where the nerves and blood vessels enter through the apical foramen.
- Sulcus (gingival)
- The shallow groove between the free gingiva and the tooth surface; probed to assess periodontal health.
- Mandibular vs maxillary teeth (charting)
- Maxillary teeth are upper; mandibular teeth are lower. Always confirm arch and side before charting.
- Curing — incremental placement of composite
- Composite is placed and cured in thin increments to ensure complete polymerization and reduce shrinkage.
- Etch-rinse vs self-etch bonding
- Etch-rinse uses separate phosphoric-acid etching; self-etch primers combine etching and priming in fewer steps.
- Glass ionomer
- A tooth-colored material that bonds chemically to tooth structure and releases fluoride; used as a base, liner, or restorative.
- Impression tray types
- Stock trays (preformed) and custom trays (made on a patient model) hold impression material against the arch.
- Bite registration
- A record of how the upper and lower teeth occlude, used by the lab to mount models correctly.
- Gypsum (dental stone/plaster)
- Powder mixed with water that sets into a hard model when poured into an impression.
- Crown (clinical vs anatomical)
- Anatomical crown = the enamel-covered part; clinical crown = the part visible in the mouth above the gingiva.
- Furcation
- The area where the roots of a multi-rooted tooth divide; furcation involvement indicates periodontal bone loss.
- Mobility (tooth)
- Looseness of a tooth, graded by degree; increased mobility can indicate periodontal disease or trauma.
- Operative (restorative) dentistry
- The branch focused on restoring teeth damaged by caries or trauma — fillings, crowns, and related procedures.
- Prosthodontics
- The specialty that replaces missing teeth with fixed or removable prostheses (crowns, bridges, dentures, implants).
- Oral and maxillofacial surgery
- The specialty performing extractions, implants, and surgery of the mouth, jaws, and face.
- Orthodontics
- The specialty correcting tooth and jaw alignment (malocclusion) with appliances such as braces and aligners.
- Pedodontics (pediatric dentistry)
- The specialty providing dental care for infants, children, and adolescents.
- Dental implant
- A titanium post surgically placed in the jawbone to support a crown, bridge, or denture.
- Aspirating before injection — why
- To confirm the needle is not in a blood vessel, preventing the anesthetic from being delivered intravascularly.
- Most common dental disease
- Dental caries (tooth decay) — caused by acid from bacterial plaque demineralizing enamel.
- Plaque (biofilm)
- A sticky bacterial film on teeth; if not removed it mineralizes into calculus and contributes to caries and gum disease.
- Gingivitis vs periodontitis
- Gingivitis is reversible gum inflammation; periodontitis adds irreversible loss of bone and attachment.
- Patient positioning — supine
- Patient lies back nearly flat for most procedures, allowing ergonomic access for the seated team.
- Informed consent
- The patient's voluntary agreement to treatment after being told the risks, benefits, and alternatives.
- Front desk vs clinical records — privacy
- Keep patient information confidential at all times; protected health information is shared only on a need-to-know basis.
- Tactile sense (explorer)
- The feel of the explorer tip catching on a surface — used to detect caries, calculus, and rough margins.
- Three numbers in a periodontal probing record
- Depths are recorded at multiple sites per tooth (e.g., six points) to map the pocket around the whole tooth.
- Anesthetic carpule
- The pre-filled glass cartridge of local anesthetic that loads into the aspirating syringe.
- Gauge of a needle
- The diameter of the needle; a higher gauge number means a thinner needle.
- Retraction cord
- A cord packed into the gingival sulcus to displace tissue and control fluid before a crown impression.
- ICE: Standard precautions
- Treat ALL human blood, body fluids, secretions, and non-intact skin/mucous membranes as potentially infectious for every patient.
- Single most effective infection-control measure
- Hand hygiene — handwashing or alcohol-based hand rub — performed before and after every patient contact.
- Routine handwashing minimum time
- At least 15–20 seconds with soap and water (longer for a surgical scrub).
- When can an alcohol rub replace handwashing?
- When hands are NOT visibly soiled. If hands are visibly dirty or contaminated, wash with soap and water.
- Correct order to DON PPE
- Gown → mask → eyewear/face shield → gloves.
- Correct order to DOFF (remove) PPE
- Gloves → eyewear/face shield → gown → mask (remove the dirtiest item first; gloves come off first).
- Protective eyewear requirement
- Side shields, to protect the eyes from splatter, aerosols, and debris during patient care.
- When to change a surgical mask
- Between patients and whenever it becomes wet or visibly contaminated (it loses filtration when damp).
- Utility (heavy) gloves
- Puncture-resistant gloves worn for instrument cleaning and handling chemical disinfectants — not exam gloves.
- Hepatitis B vaccine — OSHA rule
- Must be offered to at-risk employees within 10 working days of assignment, at no cost to the employee.
- Three main bloodborne pathogens of concern
- Hepatitis B virus (HBV), hepatitis C virus (HCV), and HIV.
- Highest transmission risk after a single needlestick
- Hepatitis B virus (HBV) — it is the most readily transmitted of the three, which is why HBV vaccination matters.
- Tuberculosis transmission route
- Airborne — via tiny droplet nuclei that stay suspended; requires airborne (respiratory) precautions.
- Chain of infection (four+ links)
- Pathogen → reservoir/source → portal of exit → mode of transmission → portal of entry → susceptible host. Breaking any link stops it.
- Engineering controls (OSHA)
- Devices that isolate or remove a hazard — e.g., sharps containers, self-sheathing needles, biohazard labels.
- Work-practice controls (OSHA)
- Behaviors that reduce exposure — e.g., one-handed needle recapping (scoop), not bending needles, proper hand hygiene.
- Contaminated sharps disposal
- Place immediately into a labeled, puncture-resistant, leak-proof, color-coded sharps container — never recap by hand.
- When to replace a sharps container
- When it reaches the fill line (about 3/4 full) — before it overfills.
- Regulated (biohazardous) medical waste
- Items that can release blood/saliva if compressed, caked with dried blood, sharps, and extracted teeth or tissue.
- Sterilization (definition)
- A process that destroys ALL microorganisms, including bacterial spores.
- Disinfection (definition)
- Destroys many or all pathogenic microorganisms but NOT necessarily bacterial spores; used on surfaces, not critical instruments.
- Spaulding: Critical instruments
- Penetrate soft tissue or bone (e.g., surgical burs, scalpels) — must be heat-sterilized or single-use.
- Spaulding: Semicritical instruments
- Contact mucous membranes but don't penetrate (e.g., mouth mirror) — heat-sterilize when possible.
- Spaulding: Noncritical surfaces/items
- Contact only intact skin (e.g., BP cuff) — intermediate- or low-level disinfection is sufficient.
- Instrument processing workflow (order)
- Receiving/cleaning → packaging → sterilization → storage — moving from dirty to clean to sterile.
- Why clean instruments before sterilizing?
- Bioburden (blood, debris) insulates microbes and blocks the sterilant; sterilization fails on dirty instruments.
- Ultrasonic cleaner
- Uses cavitation (sound-wave bubbles) to loosen and remove debris from instruments before sterilization — safer than hand-scrubbing.
- Most common sterilization method in dentistry
- Steam under pressure (the autoclave) — typically 121°C (250°F) at 15 psi for the rated cycle time.
- Dry heat sterilization
- Uses high heat without moisture; good for items corroded by steam, but needs higher temperatures and longer times.
- Chemical vapor sterilization (chemiclave)
- Uses a chemical-solution vapor under heat/pressure; preserves sharp edges (less rust) but requires ventilation.
- Biological monitor (spore test)
- Bacterial spores run through the sterilizer to verify it actually kills spores — the only true test of sterilization. Run at least weekly.
- Process indicator (external)
- Tape/markings that change color to show a package was exposed to heat — confirms processing, NOT sterilization.
- Process integrator (internal indicator)
- Placed inside a package; responds to time, temperature, and (for steam) moisture to better reflect sterilization conditions.
- Surface barriers
- Disposable covers (plastic/foil) placed on hard-to-clean surfaces and changed between patients to prevent contamination.
- Precleaning vs disinfecting surfaces
- Clean (remove bioburden) first, then disinfect with an EPA-registered hospital disinfectant — you cannot disinfect a dirty surface.
- EPA-registered disinfectant categories
- Intermediate-level (tuberculocidal, kills TB and most pathogens) and low-level — chosen by the contamination risk of the surface.
- Aseptic technique
- Practices that prevent contamination by pathogens — keeping clean items clean and avoiding cross-contamination.
- Cross-contamination
- Spread of microorganisms from one person, surface, or instrument to another.
- Dental unit waterline concern
- Biofilm can form in waterlines; flush lines and use treatments so water meets CDC quality standards (≤500 CFU/mL).
- Postexposure (needlestick) first steps
- Wash the area with soap and water, report the exposure immediately, and follow the facility's exposure-control plan and evaluation.
- Exposure Control Plan (OSHA)
- A written plan each dental office must have describing how it protects workers from bloodborne pathogen exposure; reviewed annually.
- Safety Data Sheet (SDS)
- A document giving hazard, handling, and first-aid information for each chemical in the office (Hazard Communication Standard).
- PPE (definition)
- Personal protective equipment — gloves, masks, protective eyewear, and gowns — worn to create a barrier against exposure.
- Splash/spatter vs droplet vs airborne
- Spatter = larger particles that fall quickly; droplet = small respiratory droplets (short range); airborne = tiny nuclei that linger (e.g., TB).
- Hand hygiene before gloving
- Always perform hand hygiene before donning and after removing gloves — gloves are not a substitute for handwashing.
- Latex allergy management
- Identify latex-sensitive patients/staff and use nonlatex (nitrile/vinyl) gloves and latex-free supplies.
- Heat-tolerant vs heat-sensitive items
- Heat-tolerant instruments are sterilized; heat-sensitive items are single-use or high-level disinfected per manufacturer instructions.
- Standard vs transmission-based precautions
- Standard precautions apply to ALL patients; transmission-based (contact/droplet/airborne) are added for specific known infections.
- Reusable vs single-use (disposable) devices
- Single-use devices are used once and discarded; reusable devices must be properly cleaned and sterilized between patients.
- Holding (presoak) solution
- A solution used to keep instruments moist before cleaning so debris doesn't dry and harden on them.
- CDC's role in dental infection control
- Publishes the guidelines for infection prevention in dental settings that the standard of care follows.
- OSHA's role in dental infection control
- Enforces workplace safety, including the Bloodborne Pathogens Standard and Hazard Communication, to protect employees.
- Autoclave failure — first action
- Remove the sterilizer from use, repeat the biological (spore) test, and do not use processed items until the cause is found and a passing test confirms function.
- Flash (immediate-use) sterilization
- Rapid steam sterilization of an unwrapped item for immediate use; used only when there is no alternative.
- Why packages must dry before storage
- Wet packs wick microorganisms inward ('wicking'), compromising the sterile barrier — packages must be dry before handling/storage.
- Event-related vs time-related shelf life
- Event-related: a package stays sterile until its integrity is compromised; time-related: it expires on a set date.
- Hepatitis B post-vaccination titer
- A blood test confirming the worker developed protective antibodies (immunity) after the HBV vaccine series.
- Recapping needles safely
- Use a one-handed scoop technique or a mechanical device — never a two-handed recap, which risks a needlestick.
- HIV occupational transmission risk
- Lower than HBV/HCV per single exposure, but still requires immediate reporting and post-exposure evaluation/prophylaxis.
- Immunizations recommended for dental staff
- Hepatitis B, influenza, MMR, varicella, Tdap, and others per CDC guidance for healthcare personnel.
- Biohazard label requirement
- Regulated waste containers and contaminated equipment must carry the orange-red biohazard symbol/label.
- High-level disinfection
- Destroys all microorganisms except large numbers of bacterial spores; used for heat-sensitive semicritical items when sterilization isn't possible.
- Cleaning before disinfection — surfaces
- Spray-wipe-spray (or wipe-discard-wipe): clean to remove bioburden, then apply disinfectant for the full contact (kill) time.
- Contact (kill) time of a disinfectant
- The time the surface must stay wet with the product to kill the microbes listed on the label.
- Hand care for dental staff
- Keep nails short, avoid artificial nails (harbor microbes), and cover cuts; intact skin is a barrier to infection.
- Aerosol vs spatter in dentistry
- Handpieces and ultrasonic scalers create fine aerosols (linger in air) and larger spatter; both require PPE and source control.
- Disposal of extracted teeth with amalgam
- Teeth containing amalgam are NOT placed in regular biohazard or general trash — handle as amalgam/special waste to protect the environment.
- Sterilization vs disinfection — which for instruments?
- Critical and semicritical instruments are STERILIZED; environmental surfaces are DISINFECTED.
- Heat-sterilization indicator strip color change
- Confirms the package was exposed to a heat process — it does NOT prove the contents are sterile (only a spore test does).
- Source control (respiratory)
- Having coughing patients wear a mask, use tissues, and perform hand hygiene to limit spread of respiratory pathogens.
- ALARA principle
- As Low As Reasonably Achievable — keep radiation exposure to patients and operators as low as possible.
- Paralleling technique
- The receptor is placed parallel to the long axis of the tooth and the central ray is aimed perpendicular to both — the preferred, most accurate technique.
- Bisecting angle technique
- The central ray is aimed perpendicular to an imaginary line that bisects the angle between the tooth's long axis and the receptor.
- Bitewing radiograph — best for
- Detecting interproximal (between-teeth) caries and evaluating the height of alveolar bone (crestal bone).
- Periapical radiograph — shows
- The entire tooth from crown to root apex plus surrounding bone — used to evaluate the root and periapical area.
- Panoramic radiograph
- An extraoral image showing both arches, the jaws, the TMJs, and sinuses on one film — broad coverage, less fine detail.
- Occlusal radiograph
- A larger intraoral film showing a broad area of the maxilla or mandible; the patient bites on the receptor.
- Elongation — cause
- Insufficient vertical angulation (too flat) in the bisecting technique — the image looks too long.
- Foreshortening — cause
- Excessive vertical angulation (too steep) — the image looks too short.
- Overlapping — cause
- Incorrect horizontal angulation — the central ray was not directed through the contacts, so proximal surfaces overlap.
- Cone cut
- A clear, curved unexposed area on the film caused by the position-indicating device (PID) not covering the whole receptor.
- Position-indicating device (PID / cone)
- The aiming tube that directs the x-ray beam; rectangular PIDs reduce patient exposure by limiting beam size.
- Collimation
- Restricting the size and shape of the x-ray beam (e.g., a rectangular collimator) to reduce patient exposure.
- Filtration (aluminum)
- Aluminum filters remove low-energy, nonuseful x-rays from the beam, reducing patient skin dose.
- Receptor-holding (beam alignment) device
- A device (e.g., Rinn XCP) that holds the receptor parallel to the tooth and aligns the beam — reduces cone cuts and retakes.
- Labial mounting convention
- Films are mounted with the raised (embossed) dot toward the viewer; you view the films as if facing the patient.
- Patient's right side on a mounted FMS
- Appears on the viewer's LEFT (you are facing the patient, like shaking hands).
- Scatter radiation
- Radiation deflected from its path after striking matter; it travels in all directions and is the main operator exposure source.
- Primary vs secondary vs scatter radiation
- Primary = the useful beam from the tube; secondary = produced when the beam hits matter; scatter = a type of secondary that's deflected.
- SI unit of absorbed dose
- The gray (Gy). (The traditional unit is the rad.)
- SI unit of dose equivalent (biological effect)
- The sievert (Sv). (The traditional unit is the rem.)
- Stochastic (non-threshold) effects
- Effects (like cancer) with no threshold dose — any exposure carries some probability of risk; severity is not dose-dependent.
- Deterministic (threshold) effects
- Effects that occur above a threshold dose and worsen with dose (e.g., skin erythema, cataracts).
- Most radiosensitive cells
- Cells that are young, rapidly dividing, and undifferentiated (e.g., bone marrow, reproductive cells) are most sensitive to radiation.
- Cumulative dose
- The total amount of radiation a person absorbs over a lifetime — exposure adds up, so minimize every dose.
- Dosimetry (film) badge
- A device worn by dental personnel to monitor their occupational radiation exposure over time.
- Where to wear a dosimetry badge
- On the trunk of the body (at the waist/chest), outside the lead apron — never on the same hand or near the beam.
- MPD for occupational whole-body exposure
- The maximum permissible dose for occupationally exposed workers is 50 mSv (5 rem) per year.
- MPD for non-occupationally exposed (public)
- 1 mSv (0.1 rem) per year — far lower than the occupational limit.
- Operator distance rule
- Stand at least 6 feet from the patient/tube head during exposure (or behind a barrier).
- Operator position rule (no barrier)
- Stand 90–135 degrees to the primary beam and at least 6 feet away — never in the path of the primary beam.
- Lead apron — purpose
- Shields the patient's trunk and reproductive organs from scatter radiation; used for all exposures.
- Thyroid collar — purpose
- Protects the radiosensitive thyroid gland from scatter; especially important for children and women of childbearing age.
- Why no thyroid collar for panoramic
- A thyroid collar would block part of the beam and obscure the image, so it is not used for panoramic radiography.
- kVp (kilovolt peak)
- Controls the energy/penetrating power of the x-ray beam and affects image contrast (higher kVp = lower contrast, longer scale).
- mA (milliamperage)
- Controls the number of x-rays produced (beam quantity); with time it determines density of the image.
- Exposure time
- The duration of x-ray production; with mA it controls the total quantity of radiation (and image density).
- Density (radiograph)
- The overall darkness of the image; controlled mainly by mA and exposure time (and kVp).
- Contrast (radiograph)
- The difference between light and dark areas; controlled mainly by kVp.
- Inverse square law
- Radiation intensity is inversely proportional to the square of the distance — doubling the distance cuts intensity to one-fourth.
- Image receptor types
- Film, photostimulable phosphor (PSP) plates, and direct digital sensors (CCD/CMOS).
- Digital radiography — exposure benefit
- Digital sensors need less radiation than film and give an immediate image with no chemical processing.
- Radiolucent vs radiopaque
- Radiolucent = dark areas (less dense, e.g., pulp, sinuses); radiopaque = light/white areas (dense, e.g., enamel, metal).
- Mental foramen on a radiograph
- A radiolucent (dark) area near the mandibular premolar apices that can be mistaken for periapical pathology.
- Three ways to reduce patient exposure
- Use the fastest receptor (digital/F-speed film), rectangular collimation, and a lead apron/thyroid collar (plus avoid retakes).
- Most common cause of retakes
- Operator error — cone cuts, wrong angulation, or receptor placement errors; retakes double the patient's dose.
- Patient who must not be in the room
- No one should hold the receptor or stay in the room during exposure unless absolutely necessary and properly shielded.
- Selection criteria (prescribing radiographs)
- Radiographs are ordered based on the patient's individual needs and history — not routinely — to keep exposure justified (ALARA).
- Pregnant patient radiographs
- Dental radiographs with a lead apron and thyroid collar are considered safe when necessary; defer elective imaging per clinical judgment.
- Latent period (radiation)
- The time between radiation exposure and the appearance of biological effects.
- Sources of background radiation
- Natural sources like radon, cosmic rays, and terrestrial/earth radiation that everyone is exposed to daily.
- X-ray tube components
- A cathode (filament that produces electrons) and an anode (tungsten target the electrons strike to produce x-rays).
- Central ray
- The center-most portion of the x-ray beam, aimed to achieve correct angulation onto the receptor.
- Vertical vs horizontal angulation
- Vertical angulation (up/down) controls elongation/foreshortening; horizontal angulation (side to side) controls overlapping.
- Processing error: light/thin image
- Underexposure or underdevelopment, or too low mA/time — the image appears too light.
- Processing error: dark image
- Overexposure or overdevelopment, or too high mA/time — the image appears too dark.
- Herringbone (tire-track) pattern
- Appears when film is exposed backward (the lead foil's embossed side faces the beam) — reposition the film correctly.
- Double exposure
- Two images on one film/sensor area from exposing the same receptor twice — separate exposed and unexposed receptors.
- Blurred image — cause
- Patient, tube head, or receptor movement during exposure — stabilize all three and re-expose.
- Fog (radiograph)
- An overall gray, low-contrast image from stray radiation, light leaks, old/heat-stored film, or chemical contamination.
- Reticulation
- A cracked, network appearance from a sudden large temperature change between processing solutions (film).
- Developer vs fixer (film processing)
- Developer makes the latent image visible (blackens exposed silver); fixer removes unexposed silver and hardens the emulsion.
- Why use the fastest receptor
- Faster film/digital sensors require less radiation for a diagnostic image, lowering patient dose (ALARA).
- Rectangular vs round collimation
- Rectangular collimation matches the receptor shape and exposes far less tissue than a round beam — preferred for dose reduction.
- Full-mouth series (FMS)
- A complete set of intraoral radiographs (periapicals + bitewings) showing all teeth and surrounding structures.
- Vertical bitewing — use
- Oriented tall to capture more bone height; useful for patients with periodontal bone loss.
- Children's radiographs — dose care
- Children are more radiosensitive; use shielding, fast receptors, and order images only when clinically justified.
- Edentulous patient imaging
- Panoramic imaging is often used to evaluate the jaws, residual ridges, and any retained roots before dentures or implants.
- Half-value layer (HVL)
- The thickness of material (aluminum) that reduces the beam's intensity by half — a measure of beam quality.
- Photons (x-ray)
- Packets of electromagnetic energy that make up the x-ray beam; they have no mass or charge and can ionize tissue.
- Ionizing radiation
- Radiation with enough energy to remove electrons from atoms (ionize), which can damage cells and DNA.
- Genetic vs somatic effects
- Genetic effects damage reproductive (germ) cells and may pass to offspring; somatic effects damage the exposed individual's body cells.
- Three principles of radiation protection
- Time (minimize), distance (maximize), and shielding (use barriers/lead) to reduce exposure.
- Why operators stand behind a barrier
- A protective wall/barrier absorbs scatter radiation, keeping operator exposure as low as reasonably achievable.
- Long vs short PID
- A longer PID increases the target-to-receptor distance, producing a more parallel beam and a sharper, less-magnified image.
- Receptor placement for mandibular molars
- Place the receptor low and lingual against the floor of the mouth, parallel to the teeth, with a holder for the paralleling technique.
- Exposure factors that affect patient dose
- kVp, mA, exposure time, collimation, filtration, receptor speed, and number of exposures all influence patient dose.
