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A design engineer at a dental equipment company is handed a challenging assignment. The firm’s development team must devise a suite of products that includes a new dental delivery system. The system’s improved ergonomics and compact nature will require the engineer to redesign its fluidic path. And the new suite of products must be ready for market introduction in nine months.

That’s a challenge that haunts many medical and dental equipment design engineers. The dental delivery system is a key element in the practice suite — supplying air and water to the dentist’s hand tools. It must have efficient and reliable fluid control to permit effective operator performance and patient comfort.

In the past, the engineer could have adapted a legacy fluidic path design to meet the needs of the new delivery system’s specifications. However, a host of demands are driving significant changes in fluid control design.

  • A U.S. Safe Drinking Water Act (SDWA) amendment went into effect January 4, 2014, that lowered the lead content of plumbing fittings and fixtures used with potable water to not more than a weighted average of 0.25 percent of their wetted surface areas. Fluidic path components in dental systems must comply with these regulations.
  • Dental suites are getting smaller, driving equipment and delivery systems to more compact sizes that require miniaturized fluid control components.
  • Dental practices are embracing more stylish and pleasing environments that address the psychological needs and comfort of patients. These include sleeker, more elegant, and refined delivery system armatures, controls, and tools.
  • Improved equipment ergonomics has emerged as an important design issue as dentists and assistants seek relief from repetitive motion injuries. The result has been the development of new over-the-patient and rear dental delivery configurations.
  • Product development cycles are getting shorter. Times to market are shrinking from years to months, leaving less time for engineering and qualification work.

Designing an all-new fluidic path — plus qualifying and sourcing its components — has been a complex undertaking that requires considerable engineering time.

In response, engineers are beginning to embrace a promising new design strategy — pre-engineered fluid control. These plug-and-play modules simply drop into the delivery system and incorporate integrated fluidics that fulfill the needs of virtually any design. They reduce system complexity and dramatically speed up the development process.

Delivery System Fluid Control — What’s Inside?

It’s beneficial to understand the components that make up a dental delivery system’s fluidic path. These devices regulate the volume and pressure of the hand tool’s air, suction, and irrigation media. They also control the pneumatic air that drives the system’s rotary tools.

The key components of the typical fluid control system include the following types of miniature devices:

  • Liquid isolation valves control dental irrigation and flushing. Hermetic separation of the control mechanism and the fluid ensures maximum water purity and minimizes the formation of limestone on internal parts. This drastically reduces the need for cleaning and maintenance.
  • General service valves control the air and suction functions. They turn the air or vacuum on or off.
  • Proportional valves regulate the speed of the rotary tools. Controlled by a foot-pad, the valves proportionally adjust the pneumatic air that drives the tools’ turbines.
  • Manifolds hold the valves that control the system’s air and water. They also incorporate the fittings for tube attachment.
  • Flow controllers allow the user to adjust the flow of the media.

Traditional Fluid Control Design Requires a Custom Approach

Fig. 1 - Traditional fluidic path design workflow.

Traditionally, when a dental delivery system demanded a new fluidic path, the engineer developed a custom design. This approach calls for a highly iterative product development process with considerable interaction between the original equipment manufacturer (OEM) and its suppliers. However, valve suppliers’ lack of dental application knowledge left OEM engineers with limited technical support. As a result, designing an all-new fluidic path required substantial amounts of time and money.

The typical workflow to design and develop a new dental delivery system’s custom fluidics involves the following steps (see Figure 1):

  • Conceptual design: this step begins with the development of a fluidic path that integrates with the new dental suite. The delivery system’s functional capabilities and specifications must be determined.
  • Component identification: the types of components are identified that fulfill the functions required by the fluidic path.The work includes selecting material types approved for dental application, determining valve sizes and fluidic channel lengths that optimize efficiencies and flow rates, mating valves with manifolds, and developing component specifications.
  • Design review with suppliers: fluidic path design and specifics are shared with component suppliers. Product samples are procured for flow rate testing.
  • Prototype testing: fluid control system prototypes are assembled and tested to determine proper fit, channel efficiencies, and life cycle expectations for individual components.
  • Component selection and qualification: final components (valves, manifolds, flow controllers, fittings, and tubing) are chosen and qualified. Proper regulatory approvals are confirmed.
  • Component sourcing: manufacturers are selected, prices are negotiated, quality is validated, and products are shipped.

While the customized approach results in a solution designed for a specific dental delivery system, it is a time-consuming process that can require from 9 to 12 months to complete. Different manufacturers build the valves, manifolds, and flow controllers — adding supply chain complexity. Plus, the components require configuration and integration work that adds considerable time to the process.

Pre-engineered fluid control modules are flexible and have valves that can control all types of fluidic channels — air for drying or suction, liquid for irrigation, and pneumatic air for drills and rotary tools. (Credit: Emerson)

The Breakthrough: Pre-engineered Fluid Control

An alternative to custom design is now available to dental system designers. Pre-engineered fluid control eliminates the OEM design work that adds time and cost to dental equipment development. This approach follows a trend in the broader medical device market where fluid control manufacturers are offering pre-engineered assemblies that contain customizable packages of valves, manifolds, and fittings.

The pre-engineered modules are sized and configured by the fluid control manufacturer to the typical specifications and materials required for dental delivery systems. For example, pressure ratings range from 0 to 6 bars for general service valves and 0 to 3 bars for water isolation valves. The modules’ solenoids can accept 12-V, or 24-V DC power. Seals are made of ethylene propylene diene monomer (EPDM) rubber that resists contamination.

Dental equipment OEMs can easily integrate these off-the-shelf, plug-and-play fluid control modules into their designs. The assemblies are pre-qualified for dental applications and are manufactured in a ISO class 8 equivalent clean room.

In the past, a manifold module could control only one type of fluidic channel. This resulted in a complex design scheme that required multiple space-consuming devices. In contrast, a pre-engineered module is flexible and can control all types of fluidic channels — air for drying or suction, liquid for irrigation, and pneumatic air for drills and rotary tools. Each module can support three fluidic channels, and up to four modules can be mated in a system to support a total of 12 channels. For example, one manufacturer is offering three types of pre-engineered modules.

  • One configuration incorporates two channels for general service valves controlling the air and suction channels, and one channel for an isolation valve that regulates irrigation water.
  • Configuration two includes one channel for each of the three valve types: liquid isolation, general service, and proportional.
  • Configuration three has a channel for one liquid isolation valve plus two open ports that allow the OEM to add additional fluidic path functionality to the dental delivery system.
Pre-engineered fluid control enables OEMs to easily provide options that accommodate the diversity of tools required by dentists. (Credit: Emerson)

As a result, there is an almost unlimited amount of functionality available to the designer. In addition, the modules can be modified to meet specific OEM requirements.

The compact pre-engineered modules enable OEMs to provide a significant range of options that accommodate the diversity of tools required by dentists. These include pneumatic rotating tools with interchangeable tool heads for brushing, polishing, and cutting; water spray tools for wetting and cleaning teeth; air-spray tools for drying the teeth and blowing away debris; and vacuum suction tools to remove debris and liquid waste. Each module’s channels have their own manual flow controllers that allow fine tuning for maximum performance. In addition, barbed brass ports used for hydraulic and pneumatic connections reduce assembly time.

Fig. 2 - Fluidic path design with pre-engineered assemblies.

The new pre-engineered approach brings multiple benefits to dental equipment designers. Since the fluidic path comes as a single unit, engineering time is eliminated (see Figure 2). Modules can be selected, qualified, and installed in 30 days. This enables OEMs to get dental delivery systems to market faster, and reduces design cost and the nonrecurring engineering expense associated with tooling.

Conclusion

Dental industry trends, patient demands, and government regulations are changing the size, functionality, and materials of dental delivery systems. OEM engineers can no longer rely on legacy fluid control designs for the systems of the future. New fluidic paths must be developed to meet the pressures and trends of the market.

Using a traditional custom design approach for fluid control development is a time-consuming and expensive process. OEM engineers are turning to a promising alternative — pre-engineered fluid control. These highly flexible, plug-and-play modules enhance functionality, eliminate design time and engineering, dramatically reduce cost, and accelerate times to market.

This article was written by Tony Gaglio, Emerson Product Marketing Manager for ASCO, Novi, MI. He has 20 years of experience in the analytical and diagnostic instrumentation industry. For more information, visit here.