___.In its heyday, before the dramatic improvements in communications, the annual Congresses of the European Orthodontics Society (EOS), have deserved well merited appreciation; its meetings that I attended, in London, Florence, Helsinki, Gothenburg, Copenhagen, Bonn, and Rhodes, were memorable. This year, obviously to save money, the EOS had its congress on the campus of a university in a city “so small that everything is within walking distance, or a few minutes bus ride” (Aarhus, Denmark, as described in the Welcome Address of the 80^th EOS Congress). The poster viewing area and the trade exhibition were located in tents, Fig. 1, set up upon wooden pads lying on the grass (which in the first tent was thoroughly soaked, its flimsy roof offering scant protection). Due to the limited space, only one poster for each presenter was accepted.
___.Major or small-scale exhibitors (see list), had small boothes in a tent and in a poorly lit projection room, in odd spaces, marked off with tape, see Fig. 2.
___.Compare Invisalign’s presence there, Fig. 3, with the one it had at the American Association of Orthodontists, Fig. 4 and 5. To accommodate as many exhibitors as possible, eight exhibitors were squeezed in there for three days. The price paid for the rent of the minuscule, triangular space was over US$1100. Coffee was served only in “Area A”, in the narrow space between the long tables and the booths: the crowding made communication between the participant and the exhibitor almost impracticable; many attendants were drinking and eating on the lawn.
___.As one can see from the attached list, the few, small companies exhibiting there were either local or little known. Asked if they had any success, the major exhibitors’ invariable, but sad answer was, “We just had to show that we are still around”. Probably more interested in Denmark’s landmarks, few exhibitors were present through the whole program or remained until the meetings’ end.
___.The only conference room was not enough to host the some 600 registered participants (including their families), mostly from Eastern Europe: the rest had to watch the presentations from other halls, on screens. No programs or other customary basic information, such as city maps, were given to the exhibitors. Even the event’s badges given by the organizers had no names on them, probably not being necessary anyway, as nobody checked for these at the entrances.
___.In a comparison of the gatherings of the most representative orthodontic societies of the US and Europe, the last pales.. At the 104^th Annual Session of theAmerican Association of Orthodontists (AAO) held a month earlier in Orlando, FL, the total attendance was over thirty times greater (19,306), while the number of its exhibitors was 300 vs. 25 in Aarhus. The extra attention paid in the US for four days to these supporters of the meeting ranged from the Exhibit Hall Cafe/Lounge to the AAO Exhibitor Advisory Committee (EAC), a link between AAO and its exhibitors. In its session of August 13, 2004, the EAC, the chair of which is the association’s President Elect, has arrived to the general consensus that the 2004 Annual Session exceeded exhibitors’ expectations. Does EOS have anything similar, or dare to ask opinions?While none of the EOS speakers in Arhus were affiliated with industry, the AAO has traditionally hosted relevant presentations in this field.
___.Illustrative of this attitude is the fact that this writer, Dr. Claude G. Matasa, was accepted to lecture at this EOS meeting not in my capacity as the President of the Ortho-Cycle Co., but as a Professor at the University of Illinois at Chicago. However, unexpectedly, a few hours before my presentation, I was asked to pay extra money because my company had a booth there. While the content of my lecture and poster were duly printed in the Congress’ Scientific Programme (pages 154 and 338, respectively), Dr. Fraser McDonald, the EOS’s Factotum there and its journal’s Honorary Editor, conditioned my 10-minute presentation upon an extra payment to be deposited, amount equivalent to a clinician fee and about a third of the monies already paid as an exhibitor.

___.Taken aback, I remembered more gracious treatment at other recent events, and offended, I refused to pay. At the AAO’s 102^nd Annual Session in Philadelphia, where I was in the same situation, lecturer and exhibitor, instead of paying, I was paid for my presentation. A year before, at the EOS’s congress in Prague, where I didn’t apply as an exhibitor, not only I was not asked for money, but was complimented both by the at the time President of EOS as by the above mentiond EOS’s Factotum, as one can see from Fig. 7 & 8.
___.Was my scientific status inadequate? I have authored over 120 scientific papers, patents, chapters and books (see www.Matasa.net). I am teaching at universities both in US and Europe, and am also a Consultant and Referee for the American Association of Orthodontists. Quite indicative of my recognition is the fact that Dr. F. McDonald has chosen me to refer on EOS’s journal’s scientific manuscripts, Fig. 9.
___.Was my proposed presentation in Prague self-serving? It dealt with bond strength improvement through surfactants, which has no relation to Ortho-Cycle’s commercial interests. Was it irrelevant to the meeting? Why then was the lecture accepted and its summary published in 2004 EOS Scientific Programme, and then scheduled to be presented Tuesday, June 8, at 17.40 pm? Was my presentation in Prague uninteresting? Why then did two journals, the Kieferorthopadische Nachrichten from Germany (www.KN-Aktuell.de) and the Dental Tribune from Singapore (www.Dental-Tribune.com),select from that whole EOS Conference only my presentation? The lecture (fragments in Fig.10 and 11) was published in both journals in two issues and is maintained accessible in its entirety in their archive. The obvious answer is that at the 80^th EOS Congress in Aarhus, I was also an exhibitor. In the mind of the organizers, I lost my magic cape of a scientist, becoming a ripe money tree instead.
___.At home, none of the professional societies I asked, would have thought to demand exhibitors to pay an extra fee, if their lectures had been accepted. Thus DJ Haman from AAO replied that the only possible extra fee would have been for special audio-visual needs. Sharon Hunt from the Southern Association of Orthodontists(sharhunt@bellsouth.net), Judith K. Salisbury from the Southwestern Society of Orthodontists(JSalis913@.aol. com) and Anne Le Berre, answering for the 6^th Sessionof the International Orthodontic Congress & the WFO in Paris (anne.leberre @europa-organisation.com), all claimed that their societies wouldn’t have asked for money. This raises the question, if the exhibitor, a representative of a trade dedicated to the support of the orthodontic profession, should deserve respect only as long as he pays; the more, the better.
___.In my view, both the clinician and the manufacturer are equally responsible for the advancement of the profession: one without the other may not fare well. Take, for example, the accomplishments of the company whose empty booth is shown in Fig. 3, Align Technologies, of which a respected clinician, Dr. Lester Kuperman from Ft. Worth, TX, wrote in our newsletter:
___.“Ladies and gentlemen, welcome to the new millennium! Orthodontics is changing! Rapidly! We should “embrace” and support those changes with open arms—a positive and encouraging attitude—while at the same time maintaining a totally objective and scientific approach. We should be so thankful that a commercial enterprise was able to raise the vast sum of money required to develop such an awesome technology...that is only in its infancy. Who else was going to do this for us? The AAO? A traditional orthodontic supplier? My only regret is that it wasn’t my idea! I’m sure none of you have heard of Lasik or MRI’s or Cardiac Cath Labs... Where has orthodontic technology been? The costs involved to develop this technology are mind-boggling... and our patients and we are the direct beneficiaries of this exciting process. We could not have afforded to develop this technology via the status quo. Rest assured more is yet to come”...
___.With the steady growth of the national and other regional orthodontic meetings, and the competition of the new upcoming and attractive WFO (September 11-15, 2005, Paris), the EOS has to try its best to win its financial supporters, instead of alienating them. Killing the goose that lays golden eggs is to sacrifice the future. It would be a pity if, heading in its new direction, this formerly prestigious society did not survive to celebrate its centenary in 2007!

Not all latex gloves behave the same

___."I am delighted to see your progress in this important research. If the results can be related directly to actual epithelilal reactions as well as overall allergenic potential, I think you have made a major contribution” (Prof. Gordon Christensen, DDS, MSD, PhD, Founder of Clinical Research Associates, a leading lecturer, author and a prominent product evaluator, May 20, 2004.
___.In its July/August 1999 issue, AAO’s “The Bulletin”¹ used a National Institute for Occupational Safety and Health (NIOSH) publication to advise clinicians on how to prevent the allergic reactions to rubber latex, as some 15% of the health workers in the US are hypersensitive. In its NIOSHTIC-2 database, the institute lists some 50 most significant papers on the matter out of the hundreds which have been published.
___.A pioneer in genomic testing and the commercialization of new diagnostic technologies, Laboratory Corporation of America, one of the world’s largest clinical laboratories which offers more than 4,400 clinical tests ranging from routine blood analyses to the most sophisticated molecular diagnostics, currently screens its patients against this sensitization, see Fig. 1
___.In The Bulletin, among other details, it was stated that the proteins associated to rubber latex can generate dermatitis, asthma and even death, and that the most effective risk management recommended is prevention. As these effects are directly related to leakage³, we have attempted to determine the degree in which a potassium permanganate gel, purple, discolors in the presence of the effluents. The more the gel’s discoloration, the higher is the leaching. This test has already been described in our newsletter,^4,5 specialty journals6 and books.^7,8
___.Subjected to an acidic solution of potassium permanganate, the organic compounds are oxidized while the dark purple-colored MnVII, turns into the nearly colorless MnII. In the industry, colorimetric tests use expensive spectrometers endowed with selectors for continuous variations of wavelength. A variation of the method is accurate enough to determine organic impurities in water9, the difference being that chemical analysis is used instead.
Materials and method.
___.Experiment I. A ready made 0.2% solution of potassium permanganate (0.05N, equivalent to 0.01M (Lab Chem, Pittsburgh, PA) was acidified with sulfuric acid (Spectrum, Gardena, CA, CAS#: 7664-93-9) to pH 2 and then gellified by thoroughly stirring it with fumed silica (Aerosil 200, Degussa, Cleveland, OH, CAS#: 7631-86-9; CAS#: 112945-52-5).
___.Twenty four rubber latex gloves from different manufacturers were cut at about an inch from the tip of the fingers and five pieces each were immersed in the gel for 48 hours and then photographed, Fig. 2.
___.Experiment II. To avoid possible differences between the gloves from the same batch or due to the size of the surfaces exposed, disks having the diameter of 1 inch were die-cut from nine of the most leaching and immersed in the same gel for 12 h. As differences continue to show up, an acidulated permanganate solution was tried instead of the gel.
___.Experiment III. A glove each of twenty nine brands shown in Table I were slightly stretched over glass cups. Four drops of the acidulated permanganate solution previously described were added within five minutes on each as well as on the control (a glass lens in position E-6), as shown in Fig. 3 and Table I (in which the last column indicates the positions). The photographs were taken after five and twenty minutes.
___.As the discoloration of drops occurred very fast in some instances, the influence of a variation in surface activity was suspected. To eliminate the cause, latex disks were extracted with a hydrotrope solution. After ten minutes stirring and heating at 70^oC as shown in Fig. 4 in a 5% soln. of Stepanate SXS ( Stepan Co.., Northfield, IL) , the disks were dried on filter paper and retested.
___.Experiment IV. The fast reaction of acidulated permanganate on rubber latex surfaces lends itself to the use of one of the most common methods of analyse, titration. In our case, the difference resides in the fact that the sample is a leaching solid.
___.A titration is the gradual addition of one reactant to another until the reaction is complete. The solution that is gradually added is called the titrant. By observing how much volume of the reactant solution (of known concentration) is required to react completely with a given surface of a reducing agent such as the latex disk, one can then determine the unknown concentration through a calculation leading to a “Permanganate Index”. While widely used in industry, this has never been applied, as far as we know, to determine the effluents from a solid sample.
___.The solution that has the known concentration is called a standard solution. The point at which just enough titrant has been added to complete the reaction is called the equivalence point and the point at which the titration is stopped is called the endpoint. Ideally the equivalence point and the endpoint are identical; in practice they rarely are. In our specific case, the difference between these two points is facilitated by the sudden disappearance of the purple color; a signal that at titration time, the reaction has been completed. Another particularity of our test resides in the fact that the titration detects only the amount of dissolved effluents at a particular time; the leaching may continue long after the test.
Latex disks were submitted under a controlled exposure (15 min) to the attack of 10 ml potassium permanganate 0.05 N found in an oxidizing solution containing 30 ml water and 10 ml sulfuric acid, 50% vol. The excess of potassium permanganate was determined by titration with oxalic acid as shown in Fig. 4. While the last acid is a reducing substance that can be readily measured, its concentration has to be continuously reported to that of the permanganate it titrates, the solutions’ factor F. The Permanganate Index I was calculated with the formula:
___.___.I=Fx10(ml. soln. permanganate 0.05N)-m(ml oxalic acid 0.05N)
___.To make sure that the conditions are similar (sample size, size, stirring, temperature, duration of the attack and oxidizing reagent composition), a “blank” of the reactants alone was run along with each set of samples. Since a temporary brownish staining of the samples was always possible, the best conditions found were obtained when just one disk was subjected to attack, when the brownish staining of the samples was absent or minimal, and no turbidity appeared after the end point of the titration. To stop the attack at titration time, the disk(s) were removed from the liquid (placed on the beaker’s wall): after the 15 minutes selected as standard, these were re-immersed for titration.

Results.
___.Experiment I. The test showed that the gel responds differently to the various “fingers” of the gloves tested, indicating that some of these leach more than the others. This can be seen by examining auras after 48 h. Thus, in Fig. 2, tray D, row 20 shows less permanganate reduced (less leaching) than the rows 23 and 24.
___.Experiment II. The use of equal surface disks, Fig. 3, showed that even if cut from different parts of several gloves of the same brand, their permanganate-reducing properties in the gel remain the same. While some disks curled, the reliability of the readings was better. As the amount of effluents released in time was found high enough, this experiment led to the replacement of the gel through a solution.
___.Experiment III. The rapid discoloration of some samples indicates strong differences in surface activity. After their extraction with the hydrotrope, the disks were not found contaminated with the latter substance, but cleaned from powders and surfactants: the treated samples showed an almost even time until the applied drops of the permanganate solution changed color.
___.Experiment IV. The titration with oxalic acid of the unreacted permanganate, left after its exposure for 15 min to latex disks, showed slight but significant differences between the samples tested. After removing powders and surfactants with the help of the hydrotrope solution, the differences leveled. As performed, the test showed that while indicative, the Permanganate Index of five samples varied only between low values, between 0.8 and 1.2, a fact which requires analytical skills.
Discussion
___.Although natural latex is the best product available for price and performance, bad reputation and litigation potential has caused customers to shy away from it and look for more expensive and mostly inferior substitutes. While many efforts were made to dispose off the proteins, protein traces still remain and cause irritation in sensitive people. The mechanism by which the proteins in latex products harm is direct contact, penetration through the skin. The sap of Hevea braziliensis is a colloidal suspension containing 30-40% rubber particles (cis-1, 4-polyisoprene), 2-3% proteins, 55-65% water , 0.1-0.5% sterol glycosides, 1.5-3.5% resins as well as carbohydrates and salts. It is generally presumed that part of the proteins form intermolecular, peptide bonds with the rubber molecules: accordingly, it is considered that some proteins inevitably remain in the latex even if subjected to a high deproteinization treatment.
___.According to the American Society for Testing and Materials (ASTM), the “total” quantity of latex proteins in latex products can be evaluated by measuring the amount of total water extractable protein followed by an assay of the protein content¹⁰. Being controversial, the standard does not purport to address all of the safety concerns. If a cleaning process could reduce their level from 100 ppm to 20 ppm, then the proteins would be below detection¹¹, leading to the belief that the latex is safe. Unfortunately, the 20 ppm proteins left might still be harmful to some.
Conclusions
___.A simple, standard use of the Permanganate Index to evaluate the proteins associated to latex has several problems:
___.a. Instead of reflecting only the content in harmful proteins, its value will comprise also the other oxidizable compounds leached from latex.
___.b. The permanganate’s combination with sulfuric acid denaturates and dissolves proteins. Participating in the reactions involved, it cannot be used to measure the preexisting amount.
___.c. Its value is conventional, as the titration reflects the amount leached in specific conditions and after a precise exposure. In fact, according to Le Chatelier’s law, part of the proteins may continue to leach long after the analysis has ended and there permangante is still around.
___.While only after more research it may become possible to achieve Dr. G. Christensen’s desire to have a ready to use detection kit, the present findings could allow skilled operators to sort risky latex products using a conventional scale: even if other ingredients will also be oxidized, less leaching will always be preferred. From the point of view of technical progress, the above findings constitute a protein-removing process based upon oxidation, using instead of sodium hypochlorite12 or chlorinated water13, a solution of potassium permanganate and sulfuric acid.
References
1. AAO Council on Scientific Affairs, Take measures to reduce, prevent allergic reaction to natural rubber latex in the orthodontic office environment. The Bulletin, 1999; 17(5): 11
2. NIOSH, www.cdc.gov./niosh/homepage.html
3. Muto CA, Sistrom M, Glove leakage rates as a function of latex content and brand: caveat emptor. Arch Surg. 2000; 135: 982-985
4. Matasa CG, Reactive gel entrapment, a new simple way to test leaching plastics, The Orthod. Mater Insider 2004; 16 (1): 3-7
5. Matasa CG, A do-it-yourself detection of leaching polymers, The Orthod. Mater Insider 2002; 14 (1): 5-8
6. Matasa CG, Screening orthodontic polymers for leaching, World J. Orthod. 2003; 4: 157-161
7. Matasa CG, Polymers in orthodontics: a present danger? In: Graber TM, Eliades T, Athanasiou AE, eds. Quintessence, Chicago, 2004
8. Matasa CG, Orthodontic Biomaterials. In Orthodontics, Current principles and techniques, Graber TM, Vanarsdall R, Vig, KW, eds., Mosby, St. Louis 2005
9. Water Quality. Determination of Permanganate Index, ISO 8660, 1988, Geneva
10. ASTM International, ASTM D5712-99, Standard Test Method for the analysis of aqueous extractable protein in natural rubber and its products using the modified Lowry method.
11.www.smtl.co.uk/MDRC/Latex/FumedSilica/fumedsilica.html
12. Pugh L, Culp; Russell D, Power-free latex articles and methods of making the same, US Patent 5,780,112, 1998
13. Momose A, Powderfree surgical gloves, Patent 4,597,108, 1986