DANB (RHS) Exam
The Dental Assisting National Board, Inc. (DANB) offers the Certified Dental Assistant (CDA) Examination for national certification purposes. In pursuit of CDA certification, candidates must successfully complete three tests – GC, RHS and ICE – in 5 years. The tests are acknowledged and/or mandatory in 37 states. The Radiation Health and Safety (RHS) examination is one of the three tests included in the CDA Exam as a whole.
Candidates must meet specific eligibility requirements before taking this assessment. Candidates can choose to take a computer-based or paper and pencil version of the test.
For the RHS assessment, you will have 1 hour and 15 minutes to finish 100 multiple-choice questions. The content of the test is broken down as follows:
- Expose and evaluate (intraoral, extraoral) – 37%
- Process – 16%
- Mount/label – 11%
- Radiation safety-patient – 24%
- Radiation safety-operator – 12%
The raw score, or the number answered correctly, will be converted to a scaled score in the 100-900 range. The minimum passing scaled score is 400. If unsuccessful in the attempt, a candidate may apply to take it again, but check with the local jurisdiction to find out if additional educational requirements have to be met first.
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DANB-RHS Practice Questions
1. A full-mouth survey generally includes:
- 14 periapical views and 4-6 bitewings
- 10 periapical views and 8 bitewings
- 14 periapical views and 4-6 bitewings and a panoramic
- 8 periapical views and 4 bitewings
2. When identifying anatomical structures and dental materials on radiograph, which of the following is TRUE?
- The enamel is radiolucent and located at the crown of the tooth
- The root canals are radiopaque and extend from the pulp chamber to the apex of the tooth
- The periodontal ligament can be visualized as radiopaque
- The dentin is not as radiopaque as enamel
3. What is the maximum permissible dose (MPD) of radiation for a dental assistant?
- 5 rem/year
- 0.5 rem/year
- 10 rem/year
- 50 rem/year
4. Which statement best describes the effects of long-term low-dose radiation exposure?
- The effect of long-term low-dose radiation exposure will cause genetic defects for both men and women in their childbearing years
- The effect of long-term low-dose radiation exposure will cause cancer
- The effect of long-term low-dose radiation exposure can cause changes at the cellular level in the human body that would be observed within 2 years
- The effect of long-term low-dose radiation exposure can cause changes at the cellular level in the human body that would not be observed for many years
5. During what stage of pregnancy is the fetus most sensitive to the effects of radiation exposure?
- Weeks 2 through 15
- Weeks 16 through 24
- Weeks 24 to term
- The entire pregnancy
Answers & Explanations
1. A: A full mouth survey (FMX) is often used in conjunction with a dental examination. It is a type of intraoral radiograph procedure. FMX includes 14 periapical views and generally 4-6 bitewings. New patients should have a full mouth series and this should be repeated as needed depending upon the need to follow up on ongoing conditions or to check for new issues. The paralleling technique is generally recommended over the bisecting technique because it causes less radiation exposure to the patient and produces a better quality image. With the parallel technique, #1 film is used and 3 or 4 images are taken of each arch (mandibular and maxillary). With the bisecting technique, #2 film is used and 3 anterior images are taken on each arch.
2. D: As a dental assistant, it is important to be able to interpret radiographs and identify structures appropriately. Structures that are visualized as radiopaque are dense structures that block the x-rays from passing through them. There may be a range of radiopacity; they may be seen as white to light gray on the film. Structures that will be viewed as radiopaque include enamel, dentin, cementum, lamina dura, interradicular bone, and interdental bone. Other radiopaque areas will include the hard palate, nasal septum, and maxillary tuberosity. Radiolucent areas on dental radiographs will appear within the range of dark gray to black. The structures are not as dense as the radiopaque structures and the x-rays are able to penetrate the structures to some degree. Structures that will be viewed as radiolucent include the pulp chamber, pulp canals, periodontal ligament, mandibular canal, lingual foramen, and mandibular foramen.
3. A: A dental assistant is considered an occupationally exposed individual to radiation. It is important to monitor exposure to radiation over the long term. There are 2 ways to measure exposure. The traditional system uses roentgen (R), the radiation absorbed dose (rad), and the roentgen equivalent in man (rem). The other system is newer and utilizes the metric system. It is called the International System of Units (SI). It measures radiation using coulomb per kilogram (c/kg), the gray (Gy), and the sievert (Sv). The National Council on Radiation Protection and Measurements (NCRP) sets the standard for the Maximum Permissible Dose (MPD). For the general public, the MPD is 0.1 rem/year (or 0.001 Sv/year using the SI system). For pregnant employees with occupational exposure, it is 0.5 rem/year (or 0.005 Sv/year using the SI system). For other workers with occupational exposure, it is 5 rem/year (0.05 Sv/year using SI system). The cumulative lifetime dose is calculated by multiplying 10 mSv times the age of the employee in years.
4. D: About half of radiation exposure in the United States occurs because of medical procedures such as x-rays, CT scans, or other types of procedures. Low doses of radiation do not cause an immediate medical or genetic effect. The effects of long-term low-dose radiation exposure are typically not seen for at least 5 to 20 years and may manifest as changes in the cellular level in the human body. The main concerns for radiation exposure are cancer and genetic defects. The chances for either to occur are possible but are less likely to occur from low-dose exposure.
5. A: During pregnancy, the adverse health effects of radiation exposure to the fetus are dependent upon the amount of radiation and the timing of the exposure. Fetuses are most sensitive to radiation during weeks 2 through 15. This is the time when the fetus is made up of cells only. Damage during this period may interfere with normal development of organs; however, because the mother absorbs most of the radiation, it is less likely that birth defects will occur from occupational exposure. A larger risk will occur if the mother inhales radioactive material or receives a very high dose of radiation. A higher dose of radiation would be the equivalent of 500 chest x-rays. Birth defects are even less likely to occur after the 26th week of pregnancy because the baby is fully formed.