Evidence-based dentistry: More than just P values

LETTERS TO THE EDITOR Send your letters to the Editor, British Dental Journal, 64 Wimpole Street, London, W1G 8YS Email . Priority will be given to letters less than 500 words long. Authors must sign the letter, which may be edited for reasons of space. Readers may now comment on letters via the BDJ website (www.bdj.co.uk). A 'Readers' Comments' section appears at the end of the full text of each letter online. DENTAL RADIOGRAPHY Gold thread therapy Sir, a 58-year-old woman presented for prosthodontic treatment. Her medical history revealed only previous breast and head and neck cancers. Extraoral and intraoral examination revealed no unusual findings apart from her partially edentulous state and extensive restorations but, in the course of investigation, multiple unusual linear radio-opacities were evident over a wide area on pantomography (Fig. 1). On further questioning the patient revealed she had undergone ‘gold thread therapy’ for facial ‘rejuvenation’. lasts 8-15 years.4 It is occasionally used in chronic diseases (eg sinusitis, arthritis, rheumatism)5 and in acupuncture. The evidence base for any therapeutic efficacy, however, is slender.6 B. Mizrahi, C. Scully By email 1. 2. 3. 4. 5. 6. Wang Y F, Wang C C, Liu K L. A woman’s secret. Filler rhinoplasty with Radiesse (Merz Aesthetics, San Mateo, CA) and gold thread implantation. Ann Emerg Med 2013; 62: 224–234. Alsaadi G, Jacobs R, Quirynen M, van Steenberghe D. Soft tissue augmentation of the cheeks detected on intra- and extraoral radiographs: a case report. Dentomaxillofac Radiol 2008; 37: 117–120. Rondo Junior W, Vidarte G, Michalany N. Histologic study of the skin with gold thread implantation. Plast Reconstr Surg 1996; 97: 256–258. Gold thread rejuvenation technology description. Available at: http://www.gold-thread.com/technology (accessed 8 May 2014). Gold thread. What is it? History of the Gold Thread method. Available at: http://www.goldthreaduk. co.uk/What_is_it.html (accessed 8 May 2014). Shin K C, Bae T H, Kim W S, Kim H K. Usefulness of Gold Thread Implantation for crow’s feet. Arch Plast Surg 2012; 39: 42–45. DOI: 10.1038/sj.bdj.2014.455 DENTAL INSTRUMENTS Operating otoscope Fig. 1 Pantomography revealed multiple unusual linear radio-opacities It is recognised that some ‘cosmetic’ procedures can be demonstrated radiographically1,2 but we are unaware of other reports on gold thread. The technique (Gold Filament, Gold Lift; Remaillage; Gold Reinforcement; Gold Silk) involves the implantation of a 99.99% pure gold thread of diameter 0.1 mm to 0.5 mm into the sub-dermal skin, the concept being that gold promotes angiogenesis, as the immediate area surrounding the thread is richer in blood vessels, and the mast cells numbers around the gold thread increase over time,3 which, it is suggested, may result in skin ‘rejuvenation’. The latest Gold Thread Implantation™ is performed with 0.1 mm gold thread and purportedly requires no anaesthesia, and is associated with no pain, no haemorrhage, and no scars – and Sir, oral examination for patients with limited oral opening presents considerable technical challenges to the examiner and can be an uncomfortable process for both examiner and patient. Most overhead or floor lights do not permit adequate examination, and headlights and mirrors, while offering more positioning flexibility and preserving hands-free feature, do not accommodate patients with more challenging oral features. Penlights can be helpful, but most are too dim and do not direct light well enough for considerable clinical use. Some clinicians have seen the benefits of using diagnostic otoscopes, which solve many of the above technical problems of examination and have the added benefit of magnification (Fenton S A. Personal communication. July 2009). Use of diagnostic otoscopes, which have a closed head not that does not permit bi-directional airflow, is limited by fogging of the lens. Use of an operating otoscope, which has an open head and is less prone to fogging, 606 eliminates all of the above challenges. Operating otoscopes may be used for oral examination with or without speculum attached (Figs 1 and 2). If hands-free use is required and the patient is to remain in one position for a prolonged period, a vice clamp and c-arm extension could also be used, but we have not found this necessary. Use of an operating otoscope for oral examination is the standard technique employed for all patients in our group, irrespective of oral opening. Fig. 1 Operating otoscope with speculum attached. While the light distribution is narrow, light is sufficient when using the magnification lens and if doing ear examination, there is no interruption of the examination process to remove the speculum Fig. 2 Operating otoscope without speculum attached. Without the speculum attached, the entire oral cavity is easily illuminated R. J. McCormick, M. I. Poling Buckhannon, USA DOI: 10.1038/sj.bdj.2014.456 EVIDENCE-BASED DENTISTRY More than just P values Sir, as dental clinicians, we should be all aware of the increased effort to incorporate an evidence-based approach BRITISH DENTAL JOURNAL VOLUME 216 NO. 11 JUN 13 2014 © 2014 Macmillan Publishers Limited. All rights reserved RISK TO FISH-EATING VERTEBRATES Sir, the European Commission Scientific Committee on Health and Environmental Risks (SCHER) has published an updated opinion on the environmental risks and indirect health effects of mercury from dental amalgam at http://ec.europa. eu/health/scientific_committees/ environmental_risks/docs/scher_o_165. pdf. The opinion seeks to cover three areas: Are mercury releases from amalgam a risk to the environment? Does mercury from amalgam which is then released into the environment harm human health? How does environmental risk from mercury in amalgam compare with risks from alternative restorative materials? The report paints pictures of best to worst case scenarios and concludes that in the local extreme examples of its worst case scenario: maximal dentist density, maximal mercury use and absence of separator devices, the risk of mercury poisoning to fish-eating vertebrates cannot be excluded. Similarly in the extreme worst cases they conclude that mitigation measures might be needed to protect humans from eating contaminated fish. Looking at alternative restorative materials they acknowledge to enable best decisions about patient care. However, there has been little discussion in dentistry of the limits of P values in interpreting the results of published studies. This is despite a growing consensus in medicine that the simple use of P values to determine whether the results of a study are valid are insufficient or misleading.1,2 Discussion of the limitations of P values are beyond the scope of this letter but there is a growing movement in medicine to include alternative approaches including Bayesian methods. The P value is the probability of observing events as extreme or more extreme than the obse (...truncated)