Fluorescence Visualization Devices in General Dentistry: Seeing the Big Picture

Preventive Dentistry Fluorescence Visualization Devices in General Dentistry: Seeing the Big Picture David C. Morgan, PhD, Chief Science Officer, LED Dental Inc. ental professionals have been might not be apparent to the na- basement membrane. traditionally limited to the ked eye, and to help specialists Duse of incandescent light for determine appropriate surgical • Increase in tissue blood con- the visual inspection of the oral margins. tent, either from inflammation cavity. Direct visualization of re- or angiogenesis (hemoglobin flected white light from mucosal The VELscope induces natural strongly absorbs fluorescence surfaces can enable the detection tissue fluorescence by illuminat- excitation [blue] and emission of gross tissue abnormalities, but ing the oral cavity with a bright light [green]). may fail to identify some early blue light. The resulting tissue disease processes (such as dys- fluorescence is significantly dim- • Presence of pigments (e.g. mel- plasia) that have not yet caused mer than the blue excitation light anin or amalgam particles) changes easily observed using in- reflected from the tissue, but can which absorb light. candescent light. be directly visualized by looking through the device’s handpiece, Fluorescence visualization de- The limitations of white light which blocks reflected light and vices are particularly sensitive have stimulated the search for al- optimizes contrast with filters to dysplasia and cancer, disease ternative modalities, and in 2006, situated along the viewing path. processes which often involve the after extensive research, the first three of the mechanisms VELscope system was approved Mucosal abnormalities often bulleted above. Inflammation, on in Canada and cleared by the present with abnormal fluores- the other hand, is a common oc- FDA in the United States. Like cence patterns that can aid the currence in the oral cavity and subsequent entries in its category, user in detecting unhealthy tis- also presents as a strong loss of such as the Identifi 3000, and the sue. Decreased tissue fluores- fluorescence, as will certain nor- Sapphire Plus Lesion Detection, cence resulting in abnormal fluo- mal tissues, usually because of the VELscope is a non-invasive, rescence patterns arises from a their high vascularity or associ- handheld device that allows the variety of causes1, including: ated blood content. Clinicians uti- direct visualization of oral-cavity lizing fluorescence devices should fluorescence. There are currently • Increases in metabolic activity familiarize themselves with the two approved indications for the in the epithelium. normal appearance and patterns use of oral fluorescence visualiza- of oral cavity fluorescence. This tion devices: to help clinicians • Breakdown of the fluorescent will better equip them to rec- detect cancerous and precancer- collagen cross-links in the con- ognize abnormal patterns when ous lesions and other lesions that nective tissue layer beneath the they present. 6|oralhealth December 2011 www.oralhealthgroup.com Preventive Dentistry By definition, the use of an of applications and methodolo- of VELscope to routine clinical adjunctive device is subordinate gies; in particular, there has been examinations resulted in the de- to a larger diagnostic picture and excellent research devoted to sur- tection of a number of mucosal should not be thought of as a gical applications. Some of the re- abnormalities not detected by the diagnostic test with a definitive search directed towards general conventional exam. These abnor- “yes/no” or “positive/negative” an- use by dentists, however, adopts malities included a number of swer. To properly understand the a narrow vision of the utility of dysplasias, as well as lichen pla- significance of the fluorescence the technology, and often fails nus and other inflammatory le- examination, it must be consid- to evaluate the device accord- sions. The study highlights an as- ered together with the head and ing to its stated indications for pect of fluorescence visualization neck visual and tactile exam — use. In particular, many authors that is often overshadowed by its which itself is embedded within compare the use of fluorescence role in the detection of oral dys- a larger diagnostic process that visualization to a head and neck plasia and cancer. Devices such includes health history, patient exam as a standalone diagnostic as the VELscope provide general interview, and biopsy when re- procedure for oral cancer, instead practitioners with a powerful tool quired. A particular fluorescence of evaluating the added value of to aid in the discovery of most pattern or loss of fluorescence can using fluorescence visualization types of oral lesions, such as viral, mean different things in differ- in combination with the head and fungal and bacterial infections; ent clinical contexts. Fluorescence neck exam for the detection of inflammation from a variety of visualization never replaces the oral disease. This confusion is causes (including lichen planus clinical judgment of the clinician puzzling, as fluorescence visual- and other lichenoid reactions); nor overrules areas of concern ization is intended to be, and is squamous papillomas, salivary discovered by means of the tradi- approved as, an adjunctive meth- gland tumours, etc. tional examination. The value of odology for the detection of all fluorescence visualization lies in oral mucosal abnormalities. CLINICAL EXAMPLES the fact that it is based on a dif- The following clinical examples ferent type of interaction with tis- There have been some notable have been chosen to illustrate the sue than conventional reflectance exceptions; Huff et al9 conducted above concepts. of white light, and can therefore an interesting retrospective anal- show the clinician areas of con- ysis comparing consecutive years Figure 1 illustrates an im- cern that may have been missed in a private dental practice. During portant point — automatically during the white light exam. This the second year a VELscope ex- associating a loss of fluorescence can lead to the early discovery amination was added to the head with pathology is misguided. of lesions, with consequent ben- and neck exam and ten dysplastic Note that the left tonsillar pil- efits: enhanced quality of care lesions were detected in the pa- lars, palatine tonsil and orophar- provision for the clinician; more tient population as compared to ynx are predominantly dark (i.e., effective, less invasive therapeu- none in the previous year. Most show a “loss of fluorescence”) tic intervention for the patient; recently, a 620-patient study at because of absorption of light by potential improvement of the pa- the University of Washington18 the associated presence of vascu- tient’s quality of life. demonstrated that the addition larity and lymphoid tissue. Not Over the past six years, considerable research has attempted to evaluate the use of fluorescence visualization (predominantly focused on the VELscope system) as an aid for the general dentist and special- ist.1-18 In addition, some re- view articles have attempted to evaluate the general ben- efits of oral cancer screening, and of adjunctive aids such as FIgurE 1—Normal factors such as vascularity and lymphoid tissue contribute to the VELscope.19-21 This work has spectrum of normal pattern variability under fluorescence visualization. encompassed a broad spectrum www.oralhealthgroup.com December 2011 oralhealth|7 Preventive Dentistry Inflammatory changes from a wide variety of causes are rel- atively commonplace. Probably the most common occurrence is trauma-associated inflammation, as seen in this example on the left buccal mucosa (Fig. 2). The subtle visual appearance under white light is trans- formed, under VELscope, into two dramatic areas of loss of FIgurE 2—Trauma-associated inflammation on the left buccal mucosa. (Images cour- fluorescence that are difficult tesy of the University of Washington Oral Medicine Program.) not to notice. Once seen, the fluorescence response together with the white light presenta- tion paints a consistent picture of the underlying cause. The two dark patches correspond to the two mildly erythema- tous areas visible under white light. The vessel damage on the upper part of the buccal surface presents predictably as a dark area under fluores- FIgurE 3—Loss of fluorescence under VELscope paired with observable inflammation cence due to blood absorption, under white light contributed to a diagnosis of oral candidiasis. (Images courtesy and is consistent with the pic- of Dr. Samson Ng.) ture of trauma from the teeth. Rather than being viewed as some sort of “false positive” or distraction, the fluorescence response should help focus the clinician on a legitimate (albeit non-life threatening) possibility of chronic trauma to the buccal mucosa, that may not have otherwise been noticed. This type of trauma can be caused FIgurE 4—Fluorescence and white light confirm the resolution of candidiasis (as pre- by parafunctional habits, sharp sented in Figure 3) after treatment. (Images courtesy of Dr. Samson Ng.) or jagged cusps or malposed teeth, and could be addressed all individuals, however, show ing of fluorescence and conven- through counseling, oral appli- this type of lymphoid aggregate tional white light photographs, ances or smoothing of rough tooth proliferation. With a little experi- even of normal appearing tissue, surfaces. ence, one becomes familiar with facilitates this process by estab- the spectrum of normal variation

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