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D esigning toothpastes and toothbrushes is a time-con- suming process involving the production and testing of numerous samples. Using a new type of simulation, various parameters such as bristle shape and abrasive particle size can be modified with just a click. This en- ables manufacturers to improve the qual- ity of new dental care products and bring them to market more quickly. When we wake up in the morning, there is a fur-like coating on our teeth: this is a biological film that forms overnight. Over time, this can lead to the development of caries — which is why it is critical that we remove this “rug” using a toothbrush. There is a large selection of dental hy- giene products on the market, includ- ing brushes whose bristles are rounded, pointed, hard, and soft. There are also brushes with bristles of varying lengths. Until now, to determine which ones clean the most thoroughly while doing as little damage to the tooth enamel as possible, manufacturers have had to conduct ex- periments. This was also the case when selecting the right abrasive particles to be used in toothpastes. Various toothpaste formulations had to be mixed and then tested on artificial tooth enamel models — a laborious task. Another drawback to this approach is that the brush, paste and enamel can be ana- lyzed only as a complete system, which means that manufacturers have a diffi- cult time determining which effects ob- served in these experiments are derived from which of the various parameters. Help has arrived in the form of a new type of simulation developed by re- searchers at the Fraunhofer Institute for Mechanics of Materials IWM in Freiburg, Germany. “With our procedure, manu- facturers of dental hygiene products can determine the cleaning effectiveness of each individual parameter in a fast, eco- nomical and reliable manner,” says IWM scientist Dr. Christian Nutto. “Unlike in real-world experiments, the individual parameters in the simulation can be eas- ily modified — be it the size, shape and quantity of abrasive particles in a tooth- paste, or the material from which they are made, or the shape and elasticity of the bristles.” Simulated tooth brushing Researchers can increase the scope of the experiments far beyond what is possible in real-world testing, and that makes a noticeable difference in the quality of the products. What effects do the shape and stiffness of the bristles have when brushing? How do the different abrasives or toothpaste viscosity affect the enamel, and how do they affect their intended target, the biofilm on the teeth? Simula- tion testing can deliver reliable answers to questions such as these, and it does so long before the manufacturer ever mixes the toothpaste. Nutto relies on SimPARTIX® simulation software developed at the IWM, which uses the Smoothed Particle Hydrodynam- ics (SPH) particle simulation method. “We specify characteristics for the abrasive particles such as density, shape and fill factor,” he says. Even parameters for the tooth enamel are included. The virtual toothbrush bristle is then rubbed over the tooth enamel, with the simulation providing data on how the scrubbing par- ticles interact with the elastic bristle. It also calculates cleaning effectiveness, as well as the aggressiveness of the abrasives Testing toothpastes, toothbrushes against the tooth enamel. Here, the team from the Powder Technology, Fluid Dy- namics group can vary the speed at which the bristles pass across the enamel as well as their pressing force. The SimPARTIX team, together with the Fraunhofer In- stitute for Algorithms and Scientific Computing SCAI, designed an additional software tool to integrate the particle simulation into standardized simulation programs. But do the findings correspond to real- ity? The comparative experiments were conducted by Dr. Andreas Kiesow and his staff at the Fraunhofer Institute for Micro- structure of Materials and Systems IMWS in Halle as well as the MikroTribologie Centrum µTC in Karlsruhe. In the tests, a brush bristle was placed in a fastener and brushed at a constant speed across an ar- tificial tooth enamel model onto which toothpaste had been applied. It was con- cluded that the simulation can precisely predict how the toothpaste and bristles will affect the tooth enamel. At a later stage, it will also be able to predict the ef- Improving dental hygiene products through virtual brushing Simulation of pressure distribution in suspensions of varying viscosities with spherical abrasive particles as a toothbrush bristle rubs against tooth enamel: The more viscous toothpaste suspension leads to greater abrasion on enamel. Fig. 1: Lower viscosity (1 mPas). Fig. 2: Higher viscosity (20 mPas). Left-side images show pressure distribution in the suspension (a deeper red indicates higher pressure). Right-side images show stress input against the tooth enamel by abrasive particles (a deeper red indicates greater abrasion). Images/Provided by Fraunhofer IWM Some 2,000-plus attendees are expect- ed at the American Dental Hygienists’ Association Center for Lifelong Learn- ing (CLL) at the 93rd Annual Session. The event will be from June 8–14 at the David Lawrence Convention Center in Pitts- burgh. The program will feature a diverse offering of continuing education pro- grams within six different tracks. Follow a track, or plot your own Attendees can choose from 30 C.E. pro- grams and elect to follow a specific track, or diversify their selections based on in- terest and educational requirements. New this year, the ADHA’s Institute for Downtown Pittsburgh to host ADHA Center for Lifelong Learning Oral Health is hosting the In Motion: 5K Run/Walk/Fun. Taking place on Thursday, June 9, at 8 p.m. along Pittsburgh’s river- front, the event will enable attendees to participate in a unique fundraising activ- ity to support the institute’s commitment to empowering, supporting and develop- ing education and research opportunities for dental hygiene professionals. “ADHA’s CLL at the 93rd Annual Ses- sion is a one-of-a-kind, all- encompassing event for dental hygiene professionals and students,” said ADHA President Jill Rethman, RDH, BA. “Each year, this signa- ture event offers outstanding opportuni- ties that include excellent educational content, fun networking events and a rewarding community outreach project. With the introduction of the In Motion: 5K Run-Walk-Fun, we’re engaging dental hygienists to participate in an exciting event that supports overall health and wellness. In addition, this event promotes opportunities for dental hygiene research and education by benefiting the ADHA’s Institute for Oral Health.” This year’s CLL again features a com- munity service day on June 8; plenary sessions slated for June 9 and 11; and an two-day (June 10–11) exhibition hall show- casing more than 125 companies involved in oral health and dental hygiene. HYGIENE TRIBUNE The World’s Dental Hygiene Newspaper ·U.S. Edition www.dental-tribune.com MAY 2016 — Vol. 9, No. 4 ” See TESTING, page C2 Low viscosity toothpaste suspension High viscosity toothpaste suspension Fig. 1 Fig. 2 “CLL is an event that offers a unique opportunity in the oral health and den- tal hygiene community,” said ADHA CEO Ann Battrell, MSDH. “All of our attendees benefit from not just the education but the experience, the networking, the en- gagement. They have the opportunity to interact with their peers, corporate spon- sors and mentors in the field to build their knowledge in oral health and create new career opportunities.” To learn more about the ADHA’s CLL at the 93rd Annual Session, you can visit www.adha.org/annual-session. (Source: ADHA)