Key takeaways
- Modern intraoral units use constant potential (DC, high-frequency) generators. They hold kilovoltage steady through the exposure, allow very short exposure times, and pair far better with digital receptors than older AC units.
- A 2024 ADA expert panel report recommends rectangular collimation for intraoral imaging, collimating the beam to the receptor wherever possible. Budget for rectangular collimators and matching holders.
- Handheld units are FDA-cleared devices, but states regulate how they are used. Some require specific shielding, storage, training, and even lead aprons for the operator.
- When there is no barrier, the operator stands at least 2 meters (about 6.5 feet) from the tube head and out of the primary beam, unless your state rule says otherwise.
- Tubehead drift, oil leaks, and error codes are technician problems. Staff handle cleaning, barriers, technique charts, and logging issues.
Every general practice owns at least one intraoral x-ray unit, and most own one per operatory. Because the units last for decades, it is common to find a 20-year-old tubehead taking images for a brand-new sensor. That mismatch is a common cause of washed-out and overexposed images. This guide covers how the units work, which type fits your office, how to run and maintain them, and what to check when you buy one. For registration and inspection rules, pair it with our guide to dental x-ray registration and inspections.
What an intraoral x-ray unit does and how it works
An intraoral unit produces a short burst of x-rays aimed through the patient's teeth at a receptor in the mouth (a digital sensor, a phosphor plate, or film). Inside the tubehead, a heated filament releases electrons, a high voltage accelerates them across the x-ray tube, and they strike a tungsten target, producing x-rays. The tubehead is filled with oil for insulation and cooling and is lined with lead. Aluminum filtration strips out the lowest-energy photons, which would add dose without adding image information, and a collimator shapes the beam before it leaves the cone.
The three settings that control exposure
- Kilovoltage (kV or kVp): controls beam energy and penetration, and therefore contrast. Most current units run between 60 and 70 kV. The ADA panel report describes 60 to 80 kV as the range for intraoral imaging.
- Tube current (mA): controls how many x-rays are produced per unit of time. Many units offer a few fixed steps; the Midmark Preva, for example, lists 4 to 7 mA settings.
- Exposure time: the setting staff actually change day to day. Digital receptors need short times, often a fraction of what film needed.
Density on the image is driven by the product of mA and time (mAs), while kV changes both density and contrast. On most modern units, staff pick a tooth or region and a receptor type on the control panel, and the unit sets time from a stored technique chart.
DC vs. AC generators
Older units use alternating current (AC, or self-rectified) generators. Their voltage rises and falls with each cycle, so the tube spends only part of each exposure at peak kilovoltage and produces a larger share of low-energy photons that the patient absorbs but that never reach the receptor. Constant potential units, usually called DC or high-frequency units, hold the kilovoltage near peak for the whole exposure. The practical results are shorter exposure times, more consistent output from one exposure to the next, and a beam better suited to digital receptors. Planmeca describes its ProX as a constant potential, microprocessor-controlled unit with exposure times that start at 0.01 seconds, which illustrates how finely a current DC unit can be adjusted.
Parts you should know
- Tubehead: the sealed housing with the tube, oil, shielding, and filtration. Not user-serviceable.
- Position indicating device (PID or cone): sets the source-to-skin distance and holds the collimator. Federal performance standards require at least 18 cm for units that operate above 50 kVp; the ADA panel recommends at least 20 cm.
- Collimator: round or rectangular. Federal rules cap a round beam at 7 cm diameter at the cone tip for most units; a rectangular collimator narrows it to roughly the receptor size.
- Arms: the horizontal and articulating arms, with springs or friction that keep the tubehead still. Drift is a common complaint.
- Control panel and timer: selects technique, shows ready and exposure indicators, and logs errors.
- Exposure switch: a dead-man switch that must be held for the full exposure. Some offices mount it outside the room.
Which type does your practice need?
Intraoral units come in three physical formats. All three can be DC units; the difference is how they attach to the building and how staff use them.
| Type | How it mounts | Best for | Trade-offs |
|---|---|---|---|
| Wall-mount (or ceiling, column, or chair-mount) | Fixed to wall backing or a structure, hardwired | Standard operatories where the unit lives permanently | Needs proper wall backing and an electrical run; arm reach must suit the chair position |
| Mobile stand | Tubehead and arm on a rolling base, plugged into an outlet | Shared use between rooms, temporary setups, rooms where walls cannot take a mount | Takes floor space, can tip if moved carelessly, cable management |
| Handheld | Battery-powered, held by the operator | Mobile and community dentistry, nursing homes, sedation cases, backup unit | State rules vary widely; operator stays in the room; more expensive per unit; battery care |
A decision guide
- Startup or buildout: plan a wall-mount unit per operatory and put the backing in the walls before drywall. See operatory buildout and design.
- Small practice with tight budget: one unit shared between two adjacent rooms on a pass-through mount can work if the layout allows it, but it slows hygiene.
- Hygiene-heavy practice: a unit in every room, with arm reach that clears the patient's head from either side, saves time at every appointment.
- Mobile, public health, or nursing home work: a handheld unit is often the only practical choice. Confirm your state's handheld rules before buying.
- Special needs or sedation cases: some offices keep one handheld as a supplement, not a replacement. A 2021 AAOMR-published position states that handheld devices should supplement, not replace, conventional equipment.
Who should buy what
Most offices should buy a DC wall-mount unit with a rectangular collimator for each operatory and treat everything else as a supplement. If you are replacing only one thing this year, replacing an AC unit that cannot time short enough for your sensors can improve images more than a new sensor would.
How to use it: daily operation
These steps are generic. Your unit's instructions for use (IFU), your state radiation rules, and your office's written radiation safety procedures come first.
Start of day
- Turn on the unit and confirm the ready indicator comes on without an error code.
- Look over the tubehead and cone for cracks, and the arm for drift. Log anything unusual.
- Confirm the correct receptor type (sensor, PSP, or film) is selected on the control panel so the technique chart matches.
- Place fresh barriers on the tubehead, cone, arm handle, and control panel if your office uses barriers there.
For each patient
- Confirm which images the dentist has prescribed. Images are ordered on clinical judgment, not by habit; the ADA and AAOMR patient selection recommendations published in January 2026 reinforce that.
- Have the patient remove eyeglasses, removable appliances, and jewelry in the field. Thyroid collars and lead aprons are no longer recommended for patients under the 2024 ADA panel report, but follow your state's rule if it still requires them.
- Use a receptor holder with an aiming ring, and align the rectangular collimator to the holder so the beam matches the receptor.
- Select the tooth region and patient size on the panel. Do not adjust exposure time to "fix" images without checking positioning first.
- Step to your protected position, maintain sight of the patient, and hold the exposure button until the exposure indicator and tone stop. Releasing early cuts the exposure short and usually means a retake.
- Review the image before moving on. If it is too light or too dark with good positioning, note it for the technique chart rather than changing settings case by case.
Between patients
- Remove barriers with gloved hands, then clean and disinfect the tubehead, cone, and handles with a product the manufacturer approves. The Preva manual, for example, calls for a moistened towel with a non-alcohol disinfectant and warns against spraying the unit directly.
- Return the arm to its folded position so it is not struck by staff or patients.
End of day
- Clean and disinfect all touched surfaces and turn off the unit if the IFU calls for it.
- Store handheld units in a secured location and put the battery on its charger.
- Record any retakes, errors, or drift in the equipment log.
Post a technique chart for each receptor type at every unit, and update it when you change sensors or PSP systems. Some states require a posted chart. A chart that still lists film times after a switch to digital is one of the most common reasons images come out burned out.
Operator position, ALARA, and ALADA
The operator's protection comes from distance, position, and barriers. The 2024 ADA panel report says that when no barrier is available, the operator should stand at least 2 meters from the tube head and out of the primary beam. Traditional teaching adds that the safest spot is roughly 90 to 135 degrees from the direction of the beam, which is where scatter is lowest. Some state rules phrase this as six feet from the patient or behind a protective barrier with a way to see the patient; Ohio's dental rule is one example. Never hold the receptor or the tubehead for a patient, and never ask a staff member to.
ALARA (as low as reasonably achievable) is the long-standing radiation protection principle. ALADA (as low as diagnostically acceptable) is a newer framing used in dental radiology that asks whether the image answers the clinical question, not whether it is as beautiful as possible. In practice both point to the same habits: prescribe images based on need, use digital receptors, use rectangular collimation, get positioning right the first time, and avoid retakes.
Rectangular collimation in practice
The 2024 ADA panel report recommends that the beam be collimated to the receptor size and shape wherever possible, using rectangular collimation for intraoral imaging. Rectangular collimation is commonly cited as reducing patient dose several-fold compared with a round 7 cm beam. The cost is technique sensitivity: a misaligned rectangular beam produces cone cuts. The fix is holders with aiming rings that lock the collimator to the receptor, and training. Some units offer a rectangular collimator as a factory option (Planmeca lists a 33 by 43 mm rectangular option for the ProX), and add-on collimators exist for round cones. Confirm any add-on is compatible with your unit and your state rules.
Handheld units: what is different
Handheld intraoral units are FDA-cleared medical devices, and current models include a clear backscatter shield at the front of the device that protects the operator's body from scatter off the patient. The DEXIS NOMAD Pro 2, for example, is described by its maker as a 60 kV DC unit with an acrylic backscatter shield and an optional rectangular collimator. The operator holds the device steady, arms extended, with the shield between the patient and the operator's body, and does not leave the room.
State rules are where handhelds get complicated. Two examples from state rules at the time of writing:
- Ohio requires a backscatter shield of at least 0.25 mm lead equivalent, limits handhelds to intraoral use, bars their use in hallways and waiting rooms, requires secure storage, and requires the operator to wear a lead apron of at least 0.25 mm lead equivalent.
- Oregon requires a permanently attached backscatter shield of 0.25 mm lead equivalent, bars use in hallways and waiting rooms, requires machine-specific operator training, and requires a report within 72 hours if a handheld unit is lost or stolen.
Other states have different rules, and they change. Before buying one, read your state radiation program's rules and ask your state program directly if anything is unclear. You can find your program through the CRCPD directory.
Never buy a handheld unit that is not FDA-cleared, including imported units sold online at low prices. A unit that does not meet federal requirements may not be registrable in your state, and it may not have adequate shielding for the operator. Ask the seller for the FDA clearance and check it before you pay.
Maintenance schedule
| Task | Frequency | Who | Notes |
|---|---|---|---|
| Barrier and disinfect tubehead, cone, handles, panel | Between patients | Assistant or hygienist | Use disinfectants the IFU allows; do not spray the unit directly |
| Visual check for cracks, drift, error codes | Daily | Clinical staff | Log issues with the date and room |
| Charge and inspect handheld batteries | Daily | Clinical staff | Use only the manufacturer's charger |
| Confirm technique chart matches receptor in use | Weekly and after any receptor change | Office manager or lead assistant | Update the posted chart |
| Image quality check with a phantom or step wedge | Monthly or per your QA program | Designated staff | Some states require receptor and processing QA records |
| Review retake log | Monthly | Dentist or office manager | Retakes point to technique, holder, or equipment problems |
| Function check of arms, switch, indicators, and labels | Annually | Qualified service technician | Midmark's Preva manual calls for an annual system function check |
| Equipment performance evaluation | At installation, then at state-set intervals | Registered service provider or qualified expert | The ADA panel suggests at least every 4 years for conventional units; your state may require more often |
| Registration renewal and records | Per state schedule | Owner or office manager | Keep the registration, Form FDA 2579, and test reports together |
Troubleshooting
Staff can check settings, positioning, power, and technique. Anything inside the tubehead, arm springs, wiring, or control electronics is for a qualified, state-registered service technician. Radiation-producing equipment is not a do-it-yourself repair.
| Symptom | Likely causes | What to try | When to call a technician |
|---|---|---|---|
| Images consistently too dark | Technique chart still set for film or a different receptor; wrong patient size setting | Confirm receptor type on the panel; review the chart with the dentist | If correct settings still overexpose, output may be off |
| Images consistently too light or noisy | Exposure time too short; kV set low; receptor problem | Check settings; take a test image on a phantom with a second receptor | If output seems low on multiple receptors |
| Cone cuts (clear or blank edge on image) | Collimator not aligned with holder or receptor | Use aiming rings; retrain on rectangular alignment | If the collimator is loose or damaged |
| Blurry images | Patient or tubehead movement; drifting arm | Stabilize the patient; wait for the tubehead to settle before exposing | If the arm will not hold position |
| Tubehead drifts up, down, or sideways | Worn arm springs, loose joints, wall mount issue | Stop using the drifting position; fold and tag the unit if it is severe | Always; arm tension and mounts are technician work |
| Early termination error or incomplete image | Exposure button released before the exposure ended | Hold until the tone and indicator stop; wait for the unit to reset | If it happens with the button held |
| Unit will not expose, ready light flashing | Tube cooling between exposures (duty cycle), power switch, loose line cord | Wait for the cool-down; check the switch and plug | If it will not become ready after cooling |
| Error code on the panel | Internal fault detected by the unit | Write down the code; power cycle once if the IFU allows | Any repeated or unexplained code |
| Oil on the tubehead, burning smell, unusual noise, visible damage | Seal failure, electrical fault, impact damage | Stop using it immediately and tag it out of service | Always, before any further use |
| Handheld battery drains quickly | Aging battery, wrong charger | Charge per IFU; use the manufacturer's charger | For battery replacement or if it will not hold a charge |
Safety and compliance
- FDA: because the x-ray source sits outside the mouth, conventional intraoral imaging units fall under the FDA's extraoral source x-ray system classification (21 CFR 872.1800, Class II); the separate intraoral source category covers devices that place the source inside the mouth. The equipment must meet the federal performance standard in 21 CFR 1020.31, which sets requirements such as minimum source-to-skin distance and maximum field size. Installers of certified components file a report of assembly (Form FDA 2579).
- State radiation control program: registration, shielding, performance testing, operator rules, dosimetry, and inspections are set by your state and vary widely. Our registration and inspection guide shows how much.
- Dental board: who may take radiographs, and with what training or certification, is set by your state dental board.
- Infection control: CDC treats the tubehead and cone as clinical contact surfaces; clean and disinfect them with an EPA-registered hospital disinfectant or protect them with barriers. See the CDC dental sterilization and disinfection summary.
- ADA guidance: the ADA's x-rays topic page links the 2024 radiation safety report and the 2026 patient selection recommendations.
Radiation rules vary by state and change. This is general information, not legal or regulatory advice; confirm your obligations with your state radiation control program and dental board.
Buying new vs. used
Intraoral tubeheads are durable, which makes them a reasonable used purchase. The catch is that installation, registration, and performance testing cost about the same whether the unit is new or used, so the savings are smaller than the sticker suggests. See new vs. used equipment and the hidden costs of used equipment.
Used intraoral x-ray checklist
- FDA certification label present and legible, with make, model, serial number, and manufacture date
- DC (constant potential) generator, or you have a clear reason to accept an AC unit
- Shortest available exposure time suits your sensors or plates
- Rectangular collimator included or available for that model
- Arm holds any position without drifting, with no cracked joints or loose covers
- No oil residue, dents, or cracks on the tubehead
- Control panel, exposure switch, and indicators all work; no stored error codes
- Wall mount, backing plate, and arm length match your operatory layout
- Manufacturer still supplies parts for the model
- Installed by a registered installer who will file the report of assembly and handle testing
- Seller has given, or will give, any required state notice of sale
Red flags: no certification label or a label that has been removed; a tubehead with oil stains; a unit removed by someone other than a qualified technician; an AC unit priced like a DC unit; a handheld unit with no FDA clearance or no backscatter shield; a seller who cannot tell you the model's parts availability.
Rough price ranges
These are rough ranges only, and they vary by model, condition, region, and year. New DC wall-mount units from major brands generally cost in the low-to-mid thousands of dollars before installation. Used wall-mount units often sell for a fraction of that, but installation, electrical work, and testing can close much of the gap. Handheld units usually cost more than a wall-mount unit. Get installed quotes before comparing.
Lifespan
Well-maintained tubeheads commonly last well over a decade, and many run for twenty years or more. The practical end of life is usually a failed tube, an unavailable part, or an AC design that cannot keep up with digital receptors. See how long dental equipment lasts.
Brands and models you will see
Examples include the Planmeca ProX, Midmark Preva DC, DEXIS FOCUS, Dentsply Sirona Heliodent Plus, and Carestream Dental CS 2200 among wall-mount units, and the DEXIS NOMAD Pro 2 among handhelds. Older units from Gendex, Belmont, and Progeny are common on the used market. Confirm parts availability for any older model before you buy.
Related guides
A good intraoral unit is only half the image chain. Read digital dental sensors or phosphor plate scanners for the receptor side, panoramic units for extraoral imaging, and the digital sensor buying guide before replacing sensors. When you are ready to shop, browse the marketplace and run the pre-purchase checklist.
Always follow the manufacturer's instructions for use (IFU) for your specific model. Repairs involving electrical, pressure vessel, radiation, or gas line work belong with a qualified technician. Infection control and radiation rules vary by state. Prices are rough ranges that vary by model, condition, region, and year. ChairsideSource is not affiliated with any manufacturer named here.