If you are having difficulty viewing this format,

Please click the below link to view as a web-page.

[Click Here]

 

 

OPT-In Clinical Updates for May, 2013

  • Understanding Etching Porcelain
  • New Dental Laboratory Specialties
  • Advanced Technology for PFMs
  • Adhesive Systems Nuances
  • Laboratory Listings

by

Dean Mersky, DDS

 

 


Creating Excellence, Partnering in Growth

 

Who are We and Why are You Receiving This?

 

In October, 2012, Dr. Dean Mersky formed

A national cooperative of small dental laboratory owners

Dedicated to the growth and viability of Private Practice Dental Offices.

A part of our support is providing doctors with evidence-based

information about materials and techniques key to patient care.

 

 

 

Porcelain: To Etch or Not to Etch

 

 

 

The Right Way to Etch Porcelain

 

There are many different beliefs about the best way to prepare porcelain prior to bonding. Is etching with hydrofluoric acid (HF) better or worse than air abrasion? Do all ceramic materials react the same and require the same etching times? What is the best way to clean an etched surface? Does acid concentration make a difference?

 

There are many questions, but few readily available answers. Below, we provide evidence-based information to help unravel the mysteries.

 

The Role of HF

HF needs to be handled with extreme care. It can penetrate skin without burning and cause extensive damage to deeper tissues. With extreme exposures, it can even lead to death. 

 

Dental HF normally comes in 4-10% strengths. It dissolves the glass (silica) portion of ceramics to form a deeply porous surface structure. That's why etching zirconia with HF has no effect. Zirconia has no silica.

 

Left: Feldspathic porcelain etched for 5 minutes with 4% HF. A similar etching pattern is observed when 9% to 10% HF is applied for 90 seconds.

 

Two key questions are, What is the optimum etching time, and Can porcelain be over-etched?

 

HF has to be used differently for different porcelain products because of the variations in porcelain compositions and amounts of SiO2. For example, Barghi showed a 50% leucite content porcelain  required 150 to 180 seconds etching with 10% HF while a 27% leucite content ceramic required a 60-second etch with 10% HF.

 

Differences between porcelain manufacturers can vary quite wildly. IPS.emax (Ivoclar Vivadent) should have 20 seconds etching, Empress (Ivoclar Vivadent), with leucite, is recommended to have 60 seconds etching, while Jensen Industries suggests etching its leucite containing pressible ceramic, Authentic, for 5 minutes, all the above with the same 5% strength HF.

 

Don't Over-etch

Numerous studies show that etching beyond a manufacturer's recommended etching time can lead to a weaker flexural strength, and even lower resin bond strengths. One study  showed a statistically higher shear bond strength to stackable porcelain etched with 10% HF for 2 minutes compared to an etch of 4 minutes.

 

Sometimes, over-etching can lead to a white surface residue comprised of the "reaction products of porcelain and HF" forming insoluble metallic salts that can be very difficult to remove.

 

Rigth: A porcelain veneer was over-etched  with 9.5% HF (15 minutes). "Much of the clearly visible 'white residue,'  could not be removed even after an aggressive air/water spray for 2 minutes and wiping with cotton pellets soaked in acetone," according to Dr. Gary Alex. Photo by Dr. Gary Alex

 

 

Cleaning an Etched Porcelain Surface

Many resources have commented on the difficulty of cleaning an over-etched surface. Investigators suggest that restorations be placed in a baggie with alcohol or acetone, placed in ultrasonic cleaner for 5 minutes, and then scrubbed vigorously, rinsed, and dried.

 

OPT-In Dental Laboratories are all trained to use the manufacturer's recommendations when etching porcelain restorations.

 

Main reference and quotes, with appreciation to:

Compendium; July-Aug, 2008:v29, Number 6. Dr. Gary Alex

 

 

You can submit questions or find the right laboratory for your practice by contacting us at:

 

info@optindentallab.com

 

855-321-OPTN (6786)

 

or visit our website at:

 

http://www.optindentallab.com/

 

 

 

 

 

It Should be Easier to Find the Right Dental Laboratory

 

 

 

OPT-In Dental Laboratory Specialties

 

OPT-In Laboratories are grouped by their specific expertise

To simplify finding

The right laboratory for your needs.

 

OPT-In Aesthetics

  • Specialty in multi zone layering and internal staining with attention to the details of vital blending, contours, anatomy and texture for the most demanding aesthetics  

OPT-In Implants

  • Experience in complex implant cases, including fixed-removable, full-mouth fixed and removable implant restorative, milled bars, and various attachments and complex designs

OPT-In General Practice

  • Dedicated to the daily needs of general practice and the wide variety of everyday requirements dentists face, for an equally wide variety of clinical criteria and budgets

OPT-In Prosthetics and Full Mouth Reconstruction

  • Expertise in removable prosthetics, including simple and precision partial denture designs, and standard to complex over-dentures. This group is also familiar with a variety of occlusal approaches and articulators used in reconstruction

OPT-In Orthodontics

  • Provides all aspects of orthodontic laboratory services from the simplest to the most complex

 

Learn More about OPT-In Laboratory' Specialty & Expertise

 

BEGO Certified

 

Visit

 

http://www.optindentallab.com/dentists/services/choose-a-laboratory-specialities/

 

 

 

Advanced Technology Comes to PFMs

Accuracy Defined

 

 

 

 

Little Know Facts About the Advantages & Benefits of

Digitally Designed PFMs,

Using Selective Laser Melting

 

 

BEGO USA is the premier company in the US utilizing digital technology for PFM production, laser sintering of metal, also known as Selective Laser Melting, SLM. This technology was first mastered over 10 years ago at BEGO's research and development center, located in Bremen, Germany. Now, American dentists are able to experience the advantages offered by digital PFMs, including greater consistency in fit and design.

 

The SLM process begins when dental laboratories email digitally designed copings and bridges to BEGO USA. The STL file is then reviewed by a software proprietary to BEGO that certifies the design meets BEGO's SLM criteria.

 

The NP (and soon to be offered SP) SLM alloy can accurately span a full arch of precision  splinted copings and pontics, without the need for connector soldering.

 

Why Choose SLM

Laser sintering eliminates the variables and inconsistencies of metal castings. That's why close to 50 million SLM units have been manufactured world-wide. It eliminates waxing, investing, and casting that are all subject to inaccuracies caused by stresses and distortion. Moreover, because the process is CAD/CAM managed,  finished products can be designed to  improve fit by dialing in margin tolerances, specific cement gaps, consistent wall thicknesses, and maintain greater density, all important factors for porcelain strength.

 

 

 

The SLM Process

SLM is an additive process, whereby, metal particles are layered from the occlusal to the gingival margin and melted to the adjoining lower layer by a precise laser beam. The process continues until the entire coping or bridge is formed. While this is new technology for others, BEGO has established itself as a leader in SLM advancements and owns the software guiding the process.

 

BEGO USA SLM technology fits all C & B needs from single units to full arch bridges.  Its SLM  eliminates alloy shrinkage (during cooling) and C & B investment expansion that affects the fit of casted frameworks and longer span bridges. Moreover, SLM has been shown to provide predictably better fitting long span bridges when compared to traditional cast frames. This has been corroborated by recent research (abstract link, below) indicating that SLM copings fit consistently better than similar cast alloys:

http://www.demajournal.com/article/S0109-5641(10)00492-6/abstract

 

The Alloy

Historically, SLM alloy has been non precious. However, BEGO's Wirobond C+ (CTE 14.0) is Ni-free and Be-free, CoCr with 5% Mo, and provides a lighter oxide than other NP alloys.

 

Bridge is sitting upside down to illustrate the superb retention and fit at the margins of BEGO SLM.

 

Additionally, research has shown this composition to provide the high strength NP alloys are known for, while remaining corrosion resistant and very biocompatible. Below is a link to an independent research report on the biocompatibility of CoCr Mo alloy:

http://onlinelibrary.wiley.com/doi/10.1111/j.1600-0722.2011.00791.x/abstract?deniedAccessCustomisedMessage=&userIsAuthenticated=false

 

Beginning in May, 2013, BEGO will offer Semi Precious,

SLM Copings and Bridges,

The only Semi Precious SLM Bridges available.

 

All OPT-In Dental Laboratories are BEGO Certified

 

Contact us for more Information about

SLM Digital PFMs

 

info@optindentallab.com

 

 

 

http://begousa.com/

 

http://www.optindentallab.com/

 

 

Adhesives, Part 1

 

We will be featuring an ongoing section on adhesives, one of the most confusing materials topics in dentistry. In part 1, we will describe some of the differences between total etch and self-etch.

 

 

Three-step & Two-step, Total Etch

Three-step systems utilize an etch and rinse followed by a primer, then a separate adhesive. The two-step total etch is followed by a single application combining primer with adhesive. The etching process on dentin should not exceed about 15 seconds to avoid damaging the collagen that forms and, etching through the newly formed funnel shaped tubules to depths monomers can't reach. Total etch phosphoric acid pH is <1.


 

 

Top: All Bond 3 (Bisco), 3-step. HL is the hybrid layer, RT notes the resin tags.

Bottom: XP Bond (Dentsply), 2-step, note the differences in resin tags.

 

Self-etching Systems; Is Easier Better?

The self-etching approach is based on the use of non-rinse acidic monomers that simultaneously condition and prime tooth dentin and/or enamel. Regarding technique-sensitivity, this approach eliminates the rinsingg and significantly decreases technique sensitivity.

 

Questions, however, arise from this approach: Could remaining dissolved hydroxyapatite and smear layer interfere in the bond, and, are the self-etch systems able to properly demineralize enamel or sclerotic dentin?

 

Depending on etching aggressiveness, self-etch adhesives can be subdivided into strong (pH<1), intermediary strong (pH≈1.5) and mild (pH≈2.0+).

 

While one might think strong SE systems, such as Adper Prompt L-Pop (3M/Espe), might have the same strength as a 3-step total etch, research has found the opposite, 3-step systems are generally stronger. This can be due to the residual water, required for demineralization, remaining during the polymerization process of SE systems. Adhesive systems that contain high concentrations of acidic resin monomers behave like permeable membranesand allow water movement from dentin to the composite-adhesive interface. This may further compromise durability of resin-dentin bonds and affect the coupling of the self-etching adhesives to auto-cured (or dual-cured) composites.

 

Questions: info@optindentallab.com

Adper Prompt L-Pop (3M/Espe), a strong SE adhesive at pH 0.8 with long resin tags.

 


All-Bond SE, (Bisco), a mild SE adhesive at pH 2.2, with short resin tags.

Mildly acidic SE adhesives keep some hydroxyapatite crystals around collagen fibers. This may protect collagen against hydrolysis and early degradation of the bond.

 

10-MDP, present in Clearfil Liner Bond 2 and SE Bond (Kuraray Medical Inc.), 4-MET as part of Unifil Bond and G-Bond (GC), and phenyl-P found in Clearfil Liner Bond 2 (Kuraray Medical Inc.), can chemically interact with hydroxyapatite. This interaction has been connected to longer term bond strength by preventing micro and nanoleakage.

 

Longer air-drying time (10 sec.) results in significantly higher microtensile bond strength for HEMA-rich, Clearfil S Bond (Kuraray Medical Inc.) compared to  HEMA-free I Bond (Hereaus-Kulzer), and G-Bond (GC). Higher concentrations of HEMA (19-36%)in one-step SE adhesives may reduce initial bond strength due to the attraction of water and droplets on dentin, especially after delay-curing composite. This water may contribute to monomer dilution and reduction in polymerization.

 

Removing water from water rich SE systems is crucial to bond strength. However, use caution in air flow pressure. A powerful airstream can force adhesive pooling in the corners and actually denude the air stream target area. A mild and extended air-blow should help the evaporation of solvent, water, and residual monomers.

 

The above was referenced from:

http://www.scielo.br/scielo.php?pid=S1678-77572010000300002&script=sci_arttext#fig09

 

 

This Newsletter is Presented by Your

OPT-In Dental Laboratory Cooperative Partner

 

http://www.optindentallab.com/dentists/

 

Experience the Difference an OPT-In Laboratory Owner can Make

 

To Find the Right Dental Laboratory Partner for Your Practice

 

Contact Us

info@optindentallab.com

855-321-OPTN (6786)

 

Next month we will discuss restorative materials & more.

 

 

 

 

Proud OPT-In Members

Creating Excellence, Partnering in Growth

OPT-In Dental Laboratories...Always Aware of the Clinical Challenges You Face

Call Today and Experience the Difference

 

Ask for the OPT-In Laboratory Specialty You Need Most

 

 

 

All OPT-In Members own small Dental Laboratories

Dedicated to the successes of the dentists they serve,

The unique needs of each practice, and

Tailored to the individual needs of each patient.

        

                 AZ Steve Dearien                                          CA Marc Gerstel

                 Sundance Dental Laboratory                         Seabridge Dental Lab

                 877-429-3543                                                  805-985-3189

                 CA Steve Killian, CDT                                    CO Pedro Vargas, CDT

                 Killian Dental Ceramics, Inc.                          Logic Dental Solutions

                 949-733-3111                                                 303-933-9263 

                 IL Jeff Null, CDT                                            KY Marvin Janes, CDT

                 Rock Creek Dental Ceramics                          Janes Denture Services

                 618-632-2237                                                  270-932-3810

                 MD Adam Ben-Zev                                         MI Rob Teachout, CDT

                 Triple Crown Dental, Inc.                              Patriot Dental Lab

                 410-371-3885                                                 989-257-2237

                 MN Todd Mayclin, CDT                                   MN Tom Dippel

                 Mayclin Dental Studio, Inc.                           Mississippi/Minnesota Dental Lab

                 952-926-1809                                                  917-747-7519

                 NY David Birnbaum                                        NY Boris Lezaja, MDT

                 MobilTeK Labs, LLC                                        Boris Dental Lab, Inc.

                 651-457-5380                                                  516-864-2515

                 NY Kevin Crane, CDT                                     OR Mark Hidde, CDT

                 Crane Dental Laboratory, Inc.                        Rogue Valley Dental Arts, Inc.

                 585-730-5100                                                  541-779-6503
                 PA Jim Spangler, CDT                                     PA Rick Knect                                                         Select Dental Studio                                      RGK Dental Lab, Inc                              

                 717-578-6320                                                  814-445-7561

                 PA Michael Young, MDT,Joe Young                 PA Mark Walter, II, MDT

                 Young Dental Lab, Inc., CDL                           Smile Renovation Studio

                 215-334-8888                                                  570-687-0049

                 TN Dennis King                                              UT Marva, CDT, & Michele Lotsher

                 King Dental Arts Studio, Inc                          Colourtec, Inc.

                 423-573-9200                                                  801-966 8260

                 VT Bryan Booth                                             WA Mike Dominguez, CDT/TE

                 Booth Dental Lab, Inc.                                  Kymata Dental Studio Arts, Inc
                 802-234-4087                                                 206-683-9484

                                                                              

 

About the Author

Dr. Dean Mersky practiced general dentistry 26 years in Manhattan Beach, CA before spending 7     years    as  director of clinical communication for the Captek Company. Dr Mersky has been a dental lab implant coordinator, a national speaker, authored over a dozen published articles, is a regular on DentalTown.com. He launched OPT-In Management, LLC, in 2012, to help owners of small dental laboratories better understand dentists and the many clinical and business pressures facing today's private practice clinicians.
%%PLUGIN_UNSUBSCRIBE: 12179-Unsubscribe%%