Art + Science = The Digital Restorative Workflow
The Digital Restorative Workflow
Advanced materials and the latest digital technologies are having a positive impact on your crown-and-bridge caseload—improved efficiency and quality
In-office CAD/CAM systems—where indirect restorations are planned, designed, fabricated, and delivered in a single visit—may now be in use in about a third of U.S. dental practices, according to the latest survey conducted by the American Academy of Cosmetic Dentistry. That 34% of reported users, while representing a notable group, might be considered a relatively low adoption rate in light of the fact that CAD/ CAM technology has been available in dentistry for nearly 3 decades.
Perhaps the more significant statistic is the other third of AACD survey respondents who said they don’t have an in-office CAD/CAM system but are considering a purchase. The systems themselves, along with adjunct products and materials, have evolved dramatically in their simplicity, reliability, and clinical quality. So the concept of single-visit fixed prosthetics fabricated in the practice may be at its tipping point and could become the norm in the not too-distant future.
Today’s CAD/CAM dentistry components are the result of ongoing research and development, much of which is inspired by user input. Intraoral scanners are lighter, more compact, faster, and more accurate. Design software is increasingly versatile and flexible, while depending less on human intervention. Milling machines are sturdier, quicker, and precise. Add in the current selection of blocks, primarily glass ceramics and zirconia, and the digital workflow has become virtually foolproof.
Dentistry depends heavily on the newest technology to provide the best end product possible. In the pages ahead, DPS editors showcase a selection of evolving restorative dentistry innovations.
Carestream Dental’s CS 3600 uses continuous scanning technology to reduce scanning time and allow for smooth, uninterrupted capture. Interchangeable tips include a sideoriented tip for hard-to-reach areas like buccal, occlusal, and posterior areas, as well as a smaller posterior tip for improved access to posterior teeth in children and adults with smaller mouths.
The CEREC Omnicam from Dentsply Sirona CAD/CAM is a powder-free scanner with a slim and rounded camera tube for simple rotation and for patient and user comfort. Capable of capturing 2D and 3D data, it has an anti-shake feature and provides a uniform field of illumination.
3Shape’s TRIOS 3 Wireless uses long-lasting rechargeable batteries and offers easy and rapid battery exchange for nonstop scanning. The wand can be used to navigate between scan pages on the monitor, eliminating the need to touch the keyboard or mouse during scanning.
Featuring a streamlined, compact, seamless design, the Planmeca Emerald uses a multicolor laser-based system to produce realistic images with a vibrant color palette. The open architecture integrates with other systems for simplified collaboration with the lab. The tip of the scanner is autoclavable and has an active anti-fog feature.
The iTero Element Flex from Align Technology is a wandonly system for easy transport between locations. Supplied with a custom carrying case, it has a compact footprint, offers enhanced color for precise images in 60 seconds, and incorporates an intuitive, user-friendly touchpad.
Easily transported between operatories, GC America’s Aadva IOS is a cart-based system with a flexible handpiece cradle adjustment and an automatic anti-fog feature. The 19- inch touchscreen monitor provides clear diagnostic graphics and graphical user interface controls.
For end-to-end single-visit CAD/ CAM production in the practice, the major players in the market all comprise the same basic components: intraoral scanning, software, and milling units. But there are variables. As Dr. François Duret, father of CAD/CAM dentistry, advised, “Try all the different brands just as if you were buying a new car. Participate in pretraining sessions. Do not hesitate to contact the various manufacturers to try out the equipment.”
With long histories in the dental technology space, each of these established companies offer a full suite of digital systems, such as CBCT units that can be part of the CAD/CAM workflow when used to scan models. Here are some of the most popular systems.
The open STL file format of the Planmeca FIT system allows seamless integration and collaboration with other systems, and case files can be exported to any third party. The lightweight, compact Planmeca Emerald scanner is a plug-and-play unit that is easily shared between treatment rooms. Its autoclavable tip incorporates an anti-fog feature. It can be integrated into the dental unit for foot-pedal operation.
PlanCAD Easy design software guides the operator through the design process with rich graphics and intuitive navigation. It automatically adapts userspecified contact strength and creates cusps and other anatomical shapes based on adjacent teeth.
The PlanMill 30 S is designed for optimal precision by combining highperformance servo motor technology and durable milling components. Capable of reaching maximum speeds of 100,000 RPMs, a 4-axis highspeed spindle is ideal for single-visit restorations and everyday milling of inlays, onlays, crowns, or bridges.
The longest-running brand in chairside CAD/CAM, Dentsply Sirona CAD/CAM’s CEREC includes the CEREC Omnicam scanner for full-color powderless scanning; its Easy Shade analysis feature provides objective support for selecting the proper shade. It is available in mobile cart, tabletop, and integrated formats.
Offering user-friendly and intuitive operation, CEREC Software 4.6 provides better initial proposals based on biogeneric calculation along with automatic calculation of the prep margin. Its Anatomic Connector function enables the creation of interproximal spaces that realize natural tooth shape for improved esthetics.
Depending on the practice’s needs, CEREC has 3 milling units. CEREC MC is an entry-level unit ideal for single-tooth restorations from a block size up to 20 mm. CEREC MC X expands applications to bridges, abutments, and surgical guides. CEREC MC XL is a premium unit with 4 grinding motors that mill plastic, ceramic, and metal along with an optional extra-fine grinding feature and a user-friendly touch display.
As the deluxe scanning option of Carestream Dental’s CS Solutions, the CS 3600 offers 3 dedicated workflows to minimize scanning time. The restorative workflow is for in-office or lab fabrication of crowns, bridges, inlays, and onlays. The implant workflow simplifies the acquisition process for scanning abutments or scan bodies. The orthodontic workflow provides a user interface to simplify the acquisition process for digital models or ortho appliances. CS Restore design software features Automatic Margin, an advanced algorithm that automatically defines and traces the preparation margin on the model (and it can be edited manually if necessary). Additionally, occlusal surfaces can be defined with a single click; the software
reconstructs a natural occlusion based on the opposing dentition and fullarch morphology.
The 4-axis brushless motor of the CS 3000 milling machine offers high torsion resistance with minimal deviation. With an average milling time for a crown of less than 15 minutes, the unit’s high-speed, vibration-free milling creates smooth surfaces.
In many practices, monolithic crowns and bridges fabricated via CAD/CAM techniques have all but replaced PFMs. Today’s millable materials, primarily offered in block form, are available based on different chemistries, with zirconia and lithium disilicate used most widely. Each formulation has its benefits and limitations in terms of design capabilities, esthetics, and strength.
Incorporating a flexible nano-ceramic matrix, GC America’s CERASMART exhibits excellent impact dispersion, marginal integrity, and high strength after bonding. The tooth-colored, naturally opalescent material is well suited for posterior, anterior, inlay, onlay, and implant restorations and also enables minimum tooth reduction for minimally invasive restorations.
Based on Shofu’s Ceramage zirconium silicate micro ceramic, HC Block includes porous ceramic fillers for natural light transmission, durability, flexural strength, and long-lasting esthetics.
3M’s Lava Plus high-translucency zirconia is formulated with antagonist-preserving wear properties to resist abrading or roughening under occlusal load. VOCO’s Grandio blocs are made of nano-hybrid composite with an 86% filler content by weight. Requiring no firing, they impart high flexural strength and abrasion resistance. Their toothlike elasticity and thermal expansion allow for thinner crown margins.
Suitable for monolithic and pressed-to-metal restorations, Glidewell’s Obsidian is a lithium silicate ceramic formulated to simulate the function and vitality of natural dentition.
Kuraray’s KATANA Zirconia STML (Super Translucent MultiLayered) allows light transmission in the incisal area, but not in the cervical area, allowing full-contour prosthetics regardless of the abutment color.
Made of yttrium-stabilized zirconium oxide, Dentsply Sirona CAD/CAM’s Cercon exhibits high flexural strength (more than 900 MPa) along with natural esthetics. Cercon is indicated in the anterior and posterior segments for crowns, telescopic primary crowns, and multiunit bridges with no more than 2 pontics between abutment crowns and no more than 6 units.
As with the milling materials, permanent dental cements come in a variety of categories, each with their own distinct properties and indications. The newest incarnations are intended to offer ongoing health and healing benefits beyond the requisite impermeable seal and longevity. From zinc phosphate and polycarboxylate to resin and glass ionomer, cements should be selected according to the unique needs of the individual case.
Incorporating nanostructurally integrating bioceramic (NIB) chemistry, Doxa’s Ceramir Crown & Bridge integrates with natural tooth structure, is stable in the mouth, and exhibits tooth-like physical and mechanical properties. The material creates an alkaline environment with high pH to resist acid and bacterial decay.
TheraCem from BISCO is a dual-cured, calcium- and fluoride releasing, self-adhesive resin formulation that offers easy cleanup and high radiopacity. It delivers a strong bond to zirconia and other substrates.
DenMat’s self-adhesive Infinity syringes are easily placed to create non-microleaking, stress-resistant margins and eliminate the risk of postop sensitivity. It exhibits low film thickness and high fracture resistance.
Parkell’s SEcure dual-cure resin cement is supplied with complementary 4-META-based low-viscosity adhesive primer that eliminates the need for a separate etching step. Its biocompatibility creates a bond between prosthesis and tooth surface, and occludes tubules to guard against bacteria and other sensitivity-causing agents.
Containing antibacterial zinc oxide, SoloCem from COLTENE is formulated to provide high adhesion values for stability on enamel and dentin without bonding.
PANAVIA SA Cement Plus from Kuraray is self-adhesive, self-etching, fluoride-releasing, and dual curing. This next-generation cement in the PANAVIA line offers stronger shear bond strengths, faster light-curing time, and room temperature storage. It comes in auto-mix and hand-mix versions.
Formulated for simplified handling, 3M’s RelyX Unicem 2 offers convenient dispensing, an optimal consistency, and easy removal of excess. The self-adhesive resin cement is strong and moisture tolerant.
The self-etching, self-adhesive Maxcem Elite Chroma from Kerr Restoratives dispenses pink before fading at the gel state, indicating that excess is ready for cleanup. The excess cement is easily removed with the unique one-peel cleanup.
Upon application, Pentron’s Breeze conditions dentin, enamel, and the restoration in a single step, reducing procedure time and the risk of postop sensitivity.
BiFix SE from VOCO requires no refrigeration, hand mixing, or trituration. It exhibits high bond and mechanical strengths without an adhesive. Its low 10 µm film thickness cuts down on adjustment time.
Incorporating Shofu’s proprietary Giomer filler chemistry, BeautiCEM SA allows a 2-second flash cure for easy marginal cleanup. Low film thickness provides sufficient space for tight fits and undetectable margins.
SDI’s riva cem is a self-curing, paste/paste RMGI luting cement formulated without Bisphenol A or derivatives. Its light tack-cure option allows for gentle, easy removal of excess with a scaler or explorer.
Supplied in a 7-gram syringe or unit-dose mixing tips, Natural Elegance Resin Cement from Henry Schein is a dual-cure automix resin formulation. White, A2, and translucent shades are available.
Ultradent’s PermaFlo DC is highly filled (70% by weight) for maximum strength, durability, and wear resistance. The dual-cured, thixotropic luting material has a low film thickness of 9 µm.
Incorporating an anaerobic accelerator to promote complete curing, IntegraCem from Premier Dental exhibits low viscosity and film thickness to enable excess to vent uniformly for a precise marginal fit.
Tokuyama’s Bistite II DC is a selfetching, dual-cured adhesive resin formulated to provide high bond strength, low film thickness, optimal handling, and simple removal of excess. It comes in an all-inclusive self-etching kit with precious metal and ceramic primers to enhance bonding.
THE FUTURE IS UPON US
Looking ahead at fixed prosthodontics, CAD/CAM remains front and center. More and more dentists are discovering the value of integrating the digital scanning and milling workflow with cone beam imaging for improved diagnosis and treatment planning, particularly for implant-supported restorations. And new materials, accessories, and techniques—notably 3D printing— are continually entering the market to make the digital restorative workflow simpler and more clinically successful.