DANB NELDA key terms

A unit that expresses the amount of radiation exposure in air by measuring the ionization it produces. It describes exposure, not the dose actually absorbed by a person's tissue.

The amount of radiation energy actually deposited in a material or body tissue. It is measured in gray or rad and reflects how much energy the tissue received rather than how much was in the air.

The SI unit of absorbed radiation dose, equal to one joule of energy deposited per kilogram of tissue. One gray equals 100 rad.

The SI unit used to express equivalent and effective dose, adjusting absorbed dose for the biological harm of the radiation type. It is used to compare risk across exposure situations.

An acronym meaning as low as reasonably achievable. It is the guiding principle that every exposure should be kept to the minimum practical level while still producing a diagnostically acceptable image.

A rule stating that radiation intensity decreases in proportion to the square of the distance from the source. Doubling the distance from the tube reduces the intensity to one quarter.

The open-ended tube or cone attached to the x-ray head that aims the beam at the patient and limits its spread. Its length and alignment affect both exposure and image quality.

The use of metal diaphragms or shutters in the x-ray head to restrict the beam to a small, defined area. Limiting beam size reduces the volume of patient tissue exposed.

Protective garments worn by the patient during radiography that absorb scattered radiation before it reaches radiosensitive organs. The thyroid collar shields the neck, and the apron covers the torso and gonads.

Radiation that has been deflected from its original path by interaction with matter, such as the patient's tissues. It is the main source of occupational exposure in dental radiography.

A small badge worn by personnel to record cumulative occupational radiation exposure over a set period. It is read by a monitoring service to confirm that exposure stays within limits.

An intraoral image that shows the crowns of upper and lower teeth on the same film along with the crest of the alveolar bone. It is used mainly to detect interproximal caries and bone loss.

An intraoral image that shows the entire tooth from crown to root apex plus the surrounding bone. It is used to evaluate root anatomy, periapical disease, and bone height.

An intraoral method in which the image receptor is held parallel to the long axis of the tooth and the beam is directed perpendicular to both. It reduces distortion but requires a holder.

An intraoral method in which the receptor is placed along the tooth and the beam is aimed perpendicular to an imaginary line bisecting the angle between tooth and receptor. It is used when paralleling is not possible.

Distortion errors caused by incorrect vertical angulation. Elongation makes a tooth look stretched and long, while foreshortening makes it look shortened; both result from the beam not being perpendicular to the tooth and receptor.

A clear, unexposed area on a radiograph caused by the beam not covering the entire receptor. It usually results from misaimed or improperly positioned beam alignment.

A radiographic error in which the images of adjacent teeth merge because the beam was not directed through the contacts at the correct horizontal angle. It can hide interproximal caries.

The capture of x-ray images using a sensor or phosphor plate that converts radiation into electronic data instead of film. Images appear on a monitor and can be enhanced, stored, and shared electronically.

Any device that records the x-ray pattern, such as film, a digital sensor, or a phosphor storage plate. Its placement and angulation determine image quality.

Terms describing how structures appear on a radiograph. Radiolucent structures appear dark because they let x-rays pass through easily, while radiopaque structures appear light because they absorb more x-rays.

A set of infection-control practices applied to every patient regardless of known infection status. They include hand hygiene, gloves, and barriers whenever contact with blood or body fluids is possible.

Barrier items worn to prevent contact with bloodborne pathogens and other contaminants, including gloves, masks, protective eyewear, and gowns. Selection depends on the task and expected exposure.

Cleaning the hands with soap and water or an alcohol-based rub at specified moments, such as before gloving and after glove removal. It is the single most important step in preventing cross-contamination.

The sequence required for an infection to spread: a pathogen, a reservoir, a portal of exit, a mode of transmission, a portal of entry, and a susceptible host. Breaking any link prevents transmission.

A process that destroys all microorganisms, including bacterial spores, on an item. It is required for critical instruments that penetrate tissue or contact the bloodstream.

A device that sterilizes instruments using pressurized steam at high temperature. Proper loading, monitoring, and cycle verification are needed to confirm that sterilization actually occurred.

A test strip or vial containing resistant bacterial spores used to verify that a sterilizer is working. It is the most reliable routine check of sterilization effectiveness.

An item that penetrates soft tissue or contacts bone or the bloodstream and therefore must be sterile before use. Examples include scalers, surgical burs, and extraction forceps.

An item that contacts mucous membranes but does not penetrate tissue, such as a mouth mirror or impression tray. It requires at least high-level disinfection or sterilization.

A disposable plastic cover placed over items that are hard to clean or sterilize, such as light handles, chair controls, and air-water syringes. It is removed and replaced between patients.

A suction device with a wide tip that removes large volumes of saliva, blood, and aerosol near the treatment site. Its use reduces spatter and airborne contamination during procedures.

Fine airborne particles of saliva, blood, or water produced by handpieces and ultrasonic devices. Aerosols can carry microorganisms and are controlled with suction, rubber dams, and PPE.

A latex or nonlatex sheet clamped over a tooth to isolate it from the rest of the mouth. It keeps the field dry, protects the patient from debris, and reduces exposure to oral fluids.

A puncture-resistant, labeled container used to discard needles, scalpel blades, and other sharp items immediately after use. It prevents needlestick injuries and complies with disposal regulations.

A finger rest used to stabilize the hand and instruments during scaling or other fine procedures. A stable fulcrum improves control and reduces the risk of injuring soft tissue.

Measuring the depth of the gingival sulcus with a calibrated probe to assess periodontal health. Depths are recorded at several points around each tooth along with bleeding and recession.

A slender, pointed hand instrument used to detect caries, calculus, and irregularities on tooth surfaces. The sharp tip is used with light touch and a stable finger rest.

A method in which the dentist and assistant work together as a coordinated team, with the assistant anticipating needs and transferring instruments efficiently. It improves ergonomics and shortens procedure time.

The coordinated exchange of a used instrument for the next one within the assistant's transfer zone. A smooth transfer keeps the operator's hands in place and reduces procedure time.

A dental syringe with a harpoon or similar mechanism that allows the operator to pull back the plunger and check for blood before injecting. It is used to confirm that the needle is not in a blood vessel.

A drug that temporarily blocks nerve conduction in a localized area, preventing pain during dental treatment. It is delivered by injection and must be selected and dosed based on patient factors.

A device placed around a prepared tooth to hold restorative material in place and restore the contact and contour of the tooth. It is removed after the material has set.

A metallic restorative material made by mixing silver alloy powder with mercury. It is strong and durable but requires mechanical retention and careful moisture control during placement.

A tooth-colored restorative material made of resin and filler particles that is bonded to tooth structure and hardened with a curing light. It requires a dry field for reliable adhesion.

Applying an acid gel to enamel or dentin to create microscopic porosity so bonding agents and resin can grip the surface. It is a key step in adhesive dentistry.

A device that emits a specific wavelength of light to harden light-cured restorative materials. Proper tip placement and adequate exposure time are needed for full polymerization.

A negative copy of teeth and surrounding tissues made with a tray and a setting material, used to create a model or restoration. Accuracy depends on proper tray selection, material mixing, and seating.

A powder-and-water impression material derived from seaweed that sets into a flexible gel. It is used for study models and provisional work but is not dimensionally stable for long storage.

A positive reproduction of the teeth and arches poured from an impression, used for treatment planning, patient education, and records. It is also called a diagnostic cast.

Suction devices that remove fluids and debris from the mouth during treatment. The high-volume evacuator handles large volumes, while the saliva ejector removes pooled fluids in the lower areas of the mouth.