Key takeaways
- A chairside mill is one link in a chain: intraoral scanner, design software, mill, and usually a furnace for crystallizing lithium disilicate or sintering zirconia. Budget and train for the whole chain.
- Wet milling (really wet grinding) suits glass ceramics, lithium disilicate, and composites. Dry milling suits pre-sintered zirconia and PMMA. Several current mills do both.
- Lithium disilicate such as IPS e.max CAD is milled in a softer pre-crystallized state and then fired to full strength. Chairside zirconia is milled oversized in a chalky pre-sintered state and then sintered, where it shrinks to final size.
- Burs, water, and dust extraction are where many milling problems start. Track tool wear, change water and filters on schedule, and use only validated blocks and strategies.
- Same-day crowns pay off when volume is high enough to cover fixed costs and when the freed second appointment can be filled. Run the numbers with your own inputs.
Chairside CAD/CAM lets a practice scan a preparation, design a restoration, mill it from a ceramic or composite block, finish it, and seat it at the same appointment. Done well, it removes temporaries, second visits, and lab turnaround for many single-unit restorations. Done badly, it produces poorly fitting crowns and an expensive machine in a closet. This guide covers how mills work, choosing wet or dry capability, materials, daily operation, maintenance, troubleshooting, and an honest look at the economics. For the scanning side, see intraoral scanners.
What a chairside mill does and how it works
A chairside mill is a compact computer-controlled machine that cuts a restoration out of a prefabricated block using diamond or carbide tools. The design software calculates tool paths from the restoration design, and the mill moves one or more spindles and the block in coordinated axes to cut the inner (intaglio) and outer surfaces. The block is identified by the mill, often by scanning a code on the block, so the mill applies the cutting strategy validated for that material.
Some materials are finished right out of the mill after polishing. Others need a furnace step: lithium disilicate is crystallized to reach full strength and final shade, and zirconia is sintered to full density. See dental furnaces for that equipment.
Parts you should know
- Spindles and motors: hold and spin the tools. Some mills use one spindle with a tool changer; others use two opposing spindles.
- Tools (burs): diamond grinders for glass ceramics and carbide cutters for zirconia and polymers. Many mills track tool use electronically; Dentsply Sirona's CEREC Primemill uses RFID-chipped tools.
- Block holder and chamber: where the block is clamped and cut.
- Water tank, pump, and filter: supply coolant for wet grinding, usually water mixed with a manufacturer additive.
- Dust extraction: for dry milling, a suction system that removes zirconia or polymer dust.
- Touchscreen and software link: receives jobs, identifies blocks, shows tool status, and prompts maintenance.
- Calibration tools: used to calibrate the mill so restorations fit as designed.
Which type does your practice need?
Wet vs. dry milling
| Mode | Materials | How it works | Considerations |
|---|---|---|---|
| Wet (wet grinding) | Glass ceramics, lithium disilicate, zirconia-reinforced lithium silicate, feldspathic ceramics, hybrid ceramics and composites | Coolant flows over the block and tools to control heat and flush debris | Water tank, additive, filter changes, and sludge cleanup |
| Dry | Pre-sintered zirconia, PMMA and some polymers | No coolant; suction removes dust | Dust extraction, filters, and dust handling; zirconia needs a sintering furnace |
| Wet and dry combination | Both groups | Mill switches modes, with a cleaning step between | Most flexible; more maintenance routines to learn |
Current combination units include Dentsply Sirona's CEREC Primemill, which the manufacturer describes as capable of wet and dry milling and wet grinding, and Planmeca's PlanMill 35, which switches between dry milling zirconia and wet milling ceramics and composites.
Block materials
| Material | Processing | Common indications | Notes |
|---|---|---|---|
| Lithium disilicate (for example IPS e.max CAD) | Wet ground in a pre-crystallized "blue" state, then crystallized in a furnace | Crowns, onlays, inlays, veneers, some implant crowns and short bridges per the maker's indications | Ivoclar lists about 530 MPa flexural strength after crystallization and a speed program of roughly 11 minutes in its Programat CS6 |
| Zirconia | Dry milled oversized in the pre-sintered state, then sintered (it shrinks to final size) | Crowns, especially posterior; bridges per indications | Needs a sintering furnace; chairside speed-sintering programs exist |
| Zirconia-reinforced lithium silicate (for example Celtra Duo) | Wet ground; some can be seated after polishing or fired for strength | Crowns, inlays, onlays per indications | Follow the maker's firing guidance |
| Feldspathic ceramic (for example CEREC Blocs) | Wet ground; polish or glaze | Inlays, onlays, veneers, anterior crowns | Esthetic; lower strength than lithium disilicate |
| Hybrid ceramics and composites | Wet milled; polish | Inlays, onlays, some crowns per indications | No firing; easier to adjust and repair |
| PMMA | Dry or wet depending on the mill | Provisionals, try-ins | Temporary use per indications |
Always follow the block manufacturer's minimum thickness and indications. Ivoclar, for example, publishes minimum thicknesses for IPS e.max CAD by indication, and designs thinner than those minimums invite fracture. Use blocks that are validated for your mill; Dentsply Sirona describes the Primemill as compatible with about 50 validated materials.
A decision guide
- Restorative-heavy general practice: a combination wet and dry mill with a furnace covers lithium disilicate and zirconia.
- Esthetic focus, mostly anterior and onlays: a wet mill with glass ceramics may be enough.
- Low crown volume: consider sending scans to a lab instead. A scanner without a mill still removes impressions; see the economics below.
- Group practice: one mill can serve several doctors if scheduling and staffing support it. A second mill adds capacity and a backup.
- Space and utilities: plan a stable surface, electrical, network connection, and a place for water changes and sludge disposal. Dry milling adds a suction unit. Keep it out of the sterilization area to avoid dust and cross-traffic.
How to use it: daily operation
These steps are generic. Follow your mill's and block manufacturer's instructions for use (IFU).
Start of day
- Power on the mill and confirm it connects to the design software.
- Check the water level and additive concentration for wet milling, or the suction and filter status for dry milling.
- Review tool status on the screen. Replace tools the mill flags as worn before the first job, not mid-job.
- Confirm the block inventory for the day's scheduled cases, in the right shades and sizes.
For each restoration
- Scan the preparation, opposing arch, and bite, and confirm margins are clear.
- Design the restoration, checking contacts, occlusion, and minimum thickness for the chosen material.
- Select the material and block size in the software, and choose the milling mode (for example fine or fast) appropriate to the case.
- Scan or enter the block code, insert and tighten the block, close the chamber, and start the job.
- When milling ends, remove the restoration carefully, cut or grind the sprue as the IFU describes, and clean off coolant or dust.
- Try in (for lithium disilicate, often in the blue state), adjust as needed, then stain, glaze, crystallize, or sinter per the material's instructions.
- Polish or glaze, then seat per the dentist's protocol.
Between jobs and end of day
- Clean the milling chamber of sludge or dust as the mill prompts. Switching between wet and dry modes usually requires a specific cleaning or drying step.
- At the end of the day, empty and rinse the chamber, wipe seals, and leave the door as the IFU specifies (some mills should be left open to dry).
- Log jobs, block use, tool changes, and any errors.
Give one trained person ownership of the mill, including water changes, tool stock, calibration, and software updates. Mills that "belong to everyone" tend to run on overdue water, worn burs, and skipped calibrations.
Maintenance schedule
| Task | Frequency | Who | Notes |
|---|---|---|---|
| Clean milling chamber of sludge or dust | After each job or daily, as prompted | Trained assistant | Never use compressed air to blow out zirconia dust |
| Check water level and additive; check suction | Daily | Trained assistant | Use the manufacturer's additive at the specified ratio |
| Replace worn tools | When the mill flags them or per tool count | Trained assistant | Worn tools cause chipping and poor fit |
| Change water and clean tank and filter | Per manufacturer (often weekly or by job count) | Trained assistant | Stale water can smell, grow biofilm, and clog lines |
| Replace dust extraction filters or bags | Per manufacturer | Trained assistant | Handle as the SDS for the material requires |
| Calibrate the mill | Per manufacturer, after moves, and when fit drifts | Trained staff | Use the manufacturer's calibration tools |
| Software and firmware updates | As released, after compatibility check | Office manager with the dealer | Keep scanner, design, and mill software compatible |
| Inspect seals, doors, and clamps | Monthly | Trained staff | Leaks and loose clamps cause errors and damage |
| Preventive maintenance | Annually or per manufacturer | Authorized technician | Spindles, pumps, and motion systems |
Troubleshooting
Staff handle tools, water, cleaning, calibration, and software settings. Spindles, motors, pumps, electronics, and electrical work go to an authorized technician.
| Symptom | Likely causes | What to try | When to call a technician |
|---|---|---|---|
| Chipped margins or rough surfaces | Worn tools, fast mode on a thin design, wrong material selected | Replace tools; use a finer mode; confirm material and thickness | If chipping persists with new tools |
| Crowns too tight or too loose across cases | Mill out of calibration, design spacer settings, scanner calibration | Calibrate the mill and scanner; review design parameters | If calibration fails or fit drift continues |
| Tool breaks during milling | Worn tool, block not seated, wrong block type, debris in chamber | Check clamping and block code; clean chamber; replace tool | If breakage repeats with correct setup |
| Water pump or low-water error | Low level, clogged filter, air in the line | Refill with the correct mix; clean or replace the filter; follow the IFU priming steps | If the pump does not run or leaks |
| Suction or dust error in dry mode | Full filter or bag, blocked hose, suction unit off | Replace filter; check hose and connection | If suction fails with clean filters |
| Block not recognized | Damaged or dirty code, unsupported block, software database out of date | Clean the code; enter manually if allowed; update the material database | Dealer support if validated blocks are rejected |
| Lithium disilicate cracks or distorts after firing | Wrong firing program, thin areas, moisture or contamination, firing support | Confirm program and support; check thickness | Furnace service if programs are correct and failures recur |
| Zirconia crown wrong size after sintering | Wrong block data or enlargement factor, wrong sintering program | Confirm block lot data and program | If correct data still misfits |
| Mill will not connect to design software | Network change, software version mismatch | Restart both; check the network; confirm versions | Dealer or IT support |
| Grinding noise, vibration, or spindle error | Bearing wear, spindle fault | Stop use and record the error | Always |
Safety and compliance
- FDA: intraoral scanners in CAD/CAM systems are regulated as optical impression systems under 21 CFR 872.3661, Class II, and restorative blocks are regulated dental materials with labeled indications. Use each block within its cleared indications.
- Dust and chemicals: ceramic and zirconia dust and coolant additives come with safety data sheets. OSHA's Hazard Communication Standard requires that you keep SDSs available and train staff. Follow the SDS for respiratory protection and cleanup, and do not blow dust out with compressed air.
- Waste: dispose of milling sludge, coolant, and dust per the manufacturer's guidance and local rules. Do not assume the office drain is acceptable for everything.
- Furnaces: high surface temperatures and electrical requirements. Follow the furnace IFU and see dental furnaces.
- Infection control: restorations tried in the mouth before firing or final finishing are handled per your office's protocol and the material maker's instructions; keep the milling area separate from sterilization and clinical zones. See the compliance chapter.
Requirements vary by state and locality. Confirm with your own compliance advisors.
Same-day crown economics
Chairside milling does not usually raise the fee for a crown; the savings come from lab fees avoided, one fewer appointment, and no temporary. Against that sit the equipment payment, service and software fees, blocks, tools, furnace consumables, and staff time. The table below is entirely hypothetical. Every number is made up for illustration. Replace each one with your own quotes, lab fees, and staff costs.
| Hypothetical input | Example value | Notes |
|---|---|---|
| Equipment package (scanner, software, mill, furnace) | $120,000 | Financed over 7 years at 7 percent, about $1,810 per month |
| Service plan, software, and warranty | $500 per month | Varies widely by brand and bundle |
| Total fixed cost | About $2,310 per month | Paid whether you mill or not |
| Lab fee avoided per crown | $180 | Your actual lab fee |
| Block, tools, glaze and firing consumables | $68 per crown | Block cost dominates |
| Added staff time for design, milling, finishing | $10 per crown | More if the dentist does the finishing |
| Net savings per crown | $102 | $180 minus $68 minus $10 |
| Break-even volume | About 23 crowns per month | $2,310 divided by $102 |
| Hypothetical crowns per month | Savings from milled crowns | Less fixed costs | Net per month (before chair time value) |
|---|---|---|---|
| 10 | $1,020 | $2,310 | Minus $1,290 |
| 20 | $2,040 | $2,310 | Minus $270 |
| 30 | $3,060 | $2,310 | Plus $750 |
| 40 | $4,080 | $2,310 | Plus $1,770 |
This leaves out chair time. If the seat appointment you no longer need is refilled with productive work, that value can move break-even well below the table. If it is not refilled, it adds nothing. It also leaves out remakes, the doctor's time if the dentist designs and finishes, tax treatment (see Section 179 and confirm with your CPA), and financing terms (see leasing vs. financing). Your practice's crown volume, lab fees, and staffing decide the answer.
Buying new vs. used
Used mills can be good buys, but the software is the catch. Design software licenses, block databases, and mill firmware must be compatible with each other and with your scanner, and licensing for a new owner may cost extra or be unavailable. Mechanical wear is concentrated in spindles and motion systems.
Used chairside mill checklist
- Serial number confirmed with the manufacturer: supported model, software compatibility, and license transfer terms in writing
- Compatible with your scanner and design software version
- Wet, dry, or both, matching the materials you plan to use
- Spindle hours or job counts and service history available
- Test mill of a restoration, with fit checked on a model
- Calibration tools, block holders, water tank, filters, and suction unit included
- Furnace included or budgeted if you plan to use lithium disilicate or zirconia
- Deinstalled and packed per the manufacturer's transport instructions
- Local technician or dealer willing to support a secondhand unit
Red flags: a mill sold without its software license or with a license tied to the seller; an unsupported model; missing calibration tools; spindle noise or error history; a unit shipped wet with water in the tank and lines; a price that assumes software you cannot actually license.
Rough price ranges and lifespan
As rough guidance only, varying by brand, bundle, condition, region, and year: a complete new chairside package of scanner, design software, mill, and furnace is often a six-figure purchase, while a mill alone costs less. Used mills sell for a fraction of new, but licensing and support can close much of the gap. Mechanically, mills can serve for many years with maintenance; software support and spindle life usually set the practical limit. See equipment lifespan by category.
Brands and models you will see
Examples include Dentsply Sirona CEREC Primemill (and the earlier CEREC MC XL), Planmeca PlanMill 30 S, 35, and 60 S, Ivoclar PrograMill One, and Roland DGA's DWX-42W chairside wet mill. Common chairside furnaces include the Dentsply Sirona CEREC SpeedFire and Ivoclar Programat CS6.
Related guides
Milling depends on the rest of the digital chain. Read intraoral scanners, dental furnaces, and dental 3D printers (for models, provisionals, and guides), plus in-office lab equipment. Browse used units on the marketplace.
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.