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News Bulletin : ADA News Bulletin October 2011
49 OCTOBER 2011 clinical hints TEASER Isadoro Ferlito (Carlingford 2118) sent in an excellent radiographic TEASER. The respondent providing the most logical explanation for the radiopaque spots adorning the mandibular molar image will be awarded a handsome, inscribed, cast alloy ADA paperweight. If there are several such responses, they all go in a hat, and a winner will be drawn by Margaret. You get an extra slip in the hat for every clinical hint accompanying your answer. It is always a pleasure for your Columnist to receive hints, anecdotes and TEASERS, especially the last, and more especially radiographs, which always evoke an excellent response. Send yours to Barrie Gillings, Phone: 02 9144 3787; Fax: 02 9440 9159; e-mail: email@example.com The ingenuity and creativity of hinters is a constant source of joy and wonder to your Transcriber. This month they were: ANZAE (per E Rebellato), G Howe, M Knapp, I Martin, J Paterson and N Rock. sapiens successfully re-establish the normal oral flora after it has been removed by the natural process of friction from tongue, cheeks and fibrous foods. However, our modern diets require the effective use of the toothbrush and toothpaste to do this. But this is much to be preferred over the advertisers’ recommendation to kill oral micro-organisms with a mouthwash. Some patients will assume that using a mouthwash will absolve them of the need to brush their teeth and gums “because the mouthwash kills all the germs”. They can’t, they don’t, and we shouldn’t be recommending them except after special consideration of the clinical circumstances. CROWn CORK If you are a home brewer, you will be familiar with the crown cork, also known as the crown cap, crown seal or just crown. It was patented by William Painter in 1892, and was the first product of its type that was a market success. Many people collect them, because they often carry an advertisement or logo, and are small enough and inexpensive enough to permit extensive collections. The NewScientist ‘Last Word’ column published a reader’s enquiry: “Why do the crown corks always have 21 sharp bits?” Such a question is like a flame to a moth to your Expositer, who, on reading this, immediately flew into his own investigation. For ease of examination, this demanded the removal of many crown corks from a variety of bottles, and the concomitant consumption of the bottles’ contents, as he eschews wastage. But that is one of the inevitable burdens of a thorough investigation. The statement appears to be true, as every seal he examined had 21 sharp bits. As Prof Julius Sumner-Miller used to ask, “Why is it so?” Here is the first answer: The crown cork on any bottle is regulated by the internationally accepted German Standard DIN 6099, which dictates the diameter of the bottle neck, the rim form, the cap materials, and the form of the crimp. But the respondent, S Humphreys of Oxted, Surrey, did not explain why there were 21 crimps. But Chitran Durisamy, of Seven Hills, NSW did. He said that the patentee, William Painter, found empirically that the optimum crimp number was 24, and this was standard for many years. However, in 1930 a new cap metal was developed, and the crimp number was reduced to 21 for patent reasons. The next answerer was Barry Painter, of Niederhausen, Germany. He explained that the caps were originally fitted using foot-operated presses. When automatic machines were adopted, the 24 crimp caps, which were delivered by the cylindrical feed tubes, frequently jammed. An uneven number of crimps on the caps prevented this, and because the sealing effectiveness of 23 crimps was no better than 21, the 21 crimps were nominated for the standard. The standard also applies to the later-developed ‘twist-off’ caps. And how many readers noted that this last explanation was provided by a namesake of the original inventor? CLInICAL HInTS The ADA and your Columnist do not endorse or promote these hints. Dentists who submit them have found them helpful, but it is your decision whether to use them. Don’t complain about a hint; just send in a better hint. You can use a pseudonym, or be anonymous, and no one will know which hint is yours. If you have to extract a tooth which is abutting a large restoration, there is a danger of displacing the restoration. Before applying the forceps or elevator, use a long diamond bur in a high speed handpiece to shave the area of contact on the tooth to be extracted. This will ensure that the restoration is not damaged or displaced. It is sometimes difficult to angle a scalpel blade appropriately when performing a gingivoplasty. You can use a special purpose ceramic fibre bur in a high speed handpiece to sculpt the tissue, with acceptable results, but the bur is expensive and easily broken. Instead, try using a suitably shaped greenstone bur. You can run it without coolant with the advantage that the local heat will produce some cauterising. Use the sucker to remove any smell of burning. Most dentists find rubber dam a great assistance in cavity preparation. But if applied with holes for the tooth to be prepared and the abutting teeth, the interproximal section of the dam can be a problem. Consider using the ‘rubber dam cuff technique’. You simply punch dam holes for the teeth abutting the tooth to be prepared, and slit the dam between the holes. Now fit a dam clamp to the distal tooth, then stretch the dam under it and forward to the mesial abutting tooth, then hold it in place with a ‘wedgit’ or perhaps another clamp. This isolates the operating area without any interfering dam. Moisture control is not absolute, but far superior to no dam at all. After restoring a Class II cavity, some operators loosen the matrix band, then remove it, before removing any wedges. This hinter finds it preferable to remove the wedges before removing the band, but some readers may have a cogent argument for leaving them. If so, please tell us. When restoring a Class IV cavity that has a subgingival margin, using a clear Mylar matrix band is likely to result in an overhang which is difficult to remove and polish. Consider fitting a metal matrix band (such as Tofflemire) and restoring the depth of the proximal area with RMGIC such as PhotacFil. Once cured, this partial restoration will allow you to use a mylar matrix band and wedge to complete a standard composite restoration without the danger of interproximal overhang. If a tooth has inadequate supragingival tooth structure, then an indirect restoration such as a crown may not be readily achievable. But before you advise the patient that extraction is the way to go, give a thought to a direct restoration such as an amalgam crown. Always ask the patient how anxious they are to retain the tooth, and whether they would like you to try to save it. You might also discuss other options. If they don’t like the idea of an amalgam crown, you might suggest doing a conventional full crown preparation on the amalgam crown, if the latter is successful.
ADA News Bulletin September 2011
ADA News Bulletin November 2011