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News Bulletin : ADA News Bulletin September 2011
42 SePtember 2011 aesthetic update Guest author Mark Knapp Cases of ASSUmeD iDenTiTY Only the dental fraternity regularly analyse teeth in the anterior segment but almost everyone knows when a smile looks right or wrong. Popular author and physicist Paul Davies has written on how in the 1950s, scientists observed patterns amongst newly discovered subatomic particles and predicted the existence of others from anomalies in the sequence, ‘like gaps in the smile’. People understand instinctively when a smile appears somehow different. Young adults are usually missing anterior teeth because they are either congenitally absent or extracted due to severe crowding. Fortunately, loss due to trauma is uncommon. Teeth that are present tend to assume the position of the absentees to some extent, so spacing is usually only moderate. While patients are regularly dissatisfied with the appearance of their front teeth, many do not appreciate exactly the nature of the problem. TREATMEnT OPTIOnS Usually, there are a number of treatment options and all have advantages and disadvantages. Orthodontics, for instance, can reliably move teeth into an orthodox position so that the missing tooth (or teeth) can be replaced with either an implant or some type of bridge. From one perspective this is a comprehensive treatment. Narrowing of the arch, axial tilting and any centreline shifts can be corrected. Prostheses, whether pontics or implants, can achieve remarkable aesthetics. Nevertheless, many patients are reluctant to pursue such courses of treatment and perceive them as prohibitively expensive and time consuming. Some will view surgery, or the tooth preparation associated with indirect bridging, as invasive and certainly irreversible. Fig 1. Canines were grossly crowded and first premolars had drifted well mesially. “People understand instinctively when a smile appears somehow different.” Patients’ concerns must be respected. The concept of informed consent requires more than simply explaining a single, favoured treatment. It implies the dentist has a responsibility to not only advise, but, where possible, present a range of options, together with their benefits and drawbacks. There is, for instance, a significant biological, as well as financial cost incurred if a conventional bridge is placed. Research suggests that preparation for full coverage removes 63–72% of coronal structure. One study found that over a 10-year period, 29% of originally vital abutment teeth lose pulp vitality. The risk of future endodontic involvement must be explained. Without certain basic information, consent cannot be considered informed. As an alternative approach, if one tooth has assumed the basic position of another, it is possible to change its appearance to mimic that of the one it replaced. Judicious enamel contouring and direct bonding can transform a tooth’s appearance, while at the same time subtly altering its position in the arch. Upper canines can be modified to resemble lateral incisors; first premolars can virtually assume the identity of canines. CASE STUdY – COnvERTInG A fIRST PREMOLAR The patient was a 21-year-old woman, concerned about extreme crowding of her upper canines (Fig 1). First premolars had drifted some millimetres mesially and, to a lesser extent, buccally, while they had also rotated disto-buccally. The lipline was reasonably low. The patient had previously had an orthodontic consultation but did not want to pursue this treatment. Following discussion it was suggested that the canines could be extracted and the upper 4s altered to effectively replace them in the arch. It was explained that enamel trimming carried a very small risk of pulpal damage.
ADA News Bulletin August 2011
ADA News Bulletin October 2011