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Transillumination of the Oral Cavity with Use of Fiber Optics
Transillumination of the oral cavitywith use of fiber optics
Joshua Friedman, BEE, DDS Morton I. Marcus, DDS, New York
Fiber optics applied to transillum ination of teeth and other oral structures is a useful technic for de tection of caries, calculus, and soft tissue lesions. It permits a cold, high-intensity light source to be used anywhere in the oral cavity w ith ease and fle x i b ility. It often shows the degree of undermined carious tooth structure more accurately than the usual bitewing radiograph, and may aid in diagno sis of periapical and periodontal abscesses before bony destruction has occurred or swelling is ap parent.
This article describes the application of fiber optic transillum ination as a diagnostic tool for the iden tification o f caries, calculus, and soft tissue lesions in the oral cavity. F ib er optic transillum ination is particularly useful in locating decay on the p ro xi mal areas o f teeth in the posterior as well as an te rior parts of the m outh. I t is also useful for caries detection anyw here in the m outh where proxim al decay is adjacent to a radiopaque restoration, or where buccolingual decay exists in a tooth con taining a radiopaque occlusal restoration.
m itted to the other end by a process o f total in ternal reflection as shown in Figure 1. In the p ro cess o f internal reflection each fiber is clad w ith a refractive layer so that light w hich strikes the in side wall o f the fiber is reflected internally. In this m anner light can be transm itted with high effi ciency. Since applications for a single fiber are no t practical, large num bers of fibers (from 64 to 1 m illion) are clustered together to form a single bundle, ranging from 1/16 inch to 1/4 inch in d i am eter and several feet in length. In the past, fiber optics has been used in the oral cavity to provide intense illum ination of the dental operating field.3-4 F ib er optics, as we have applied it, is used as a diagnostic tool fo r the p u r pose o f transillum ination o f teeth and other oral structures. ■ Transillumination: Transillum ination, the p a s sage o f light through teeth and tissue, is n o t in
fiber optic bundle
■ Fiber optics: F ib er optics is a term given to thin cylindrical fibers o f glass o r plastic of high optical quality. A single fiber resem bling a strand of thread is often as sm all as 10/a1 (0.01 mils) in diam eter fo r the glass variety and 10 mils for plas tic.2 Light entering one end o f the fiber is trans
801
tran s Illu m in a to r
proximal decay
probe
shadow of proximal decay in enamel
shadow of proximal
decay in d e n tin
Fig 2 ■ Proximal decay on posterior teeth is observed as occlusal shadow in fiber optics transillum ination.
itself a new developm ent.5 T he principle o f tran s illum ination o f teeth is simple. It w orks because o f the different index of light transm ission for d e cay, calculus, restorative m aterials, sound tooth structure, inflam m atory exudate, and healthy periodontium . Since tooth decay has a lower in dex o f light transm ission than sound tooth struc ture, an area of decay shows up as a darkened shadow th at follows the spread o f decay along the path o f dentinal tubules6 (Fig 2). Calculus shows up as a darkened region involving the cervical th ird o f teeth. Periapical and periodontal ab scesses m ay also be diagnosed with use of fiber
optic transillum ination. A diagnosis of these co n ditions can som etim es be m ade at an early stage, at a point w here no bony destruction has occurred, w here swelling m ay not be apparent, and where a diagnosis based on a radiograph alone would be difficult.7 U nder conditions o f tissue inflam m ation w here an inflam m atory exudate exists, highly in tense light can be passed through the gingiva, root, and alveolar bone. A n abscess or any acute tissue inflam m ation shows up as a sharply circum scribed area of dim inished light transm ission.5 T his occurs because o f the buildup o f inflam m a tory exudate w hich again has an index of light transm ission lower than the surrounding area of healthy tissue. In a sim ilar m anner, translucent re storative m aterials, all of which have a different index o f light transm ission, can be differentiated from sound o r decayed tooth structure. F o r m any years, light was used in the anterior p art o f the m outh for detection o f caries. H ow ever, its use was discontinued by many dentists b e cause the lam ps w ere too bulky to be used easily in the posterior p art of the m outh. They w ere u n com fortable to the patient because they gave off too m uch heat; or else they did not produce suf ficient light ou tp u t to be used effectively. F ib er o p tics extends the range o f transillum ination. It p e r m its a cold, high-intensity light source to be used anyw here in the oral cavity with ease and flexibil
Fig 3 ■ Central incisor under normal illu m in a tio n (le ft); tra n sillu m in a te d from lingual side—black arrows in d ica te underm ined tooth structure, w h ite arrows show cervical decay (center); radiographic view (right).
802 ■ JADA, Vol. 80, April 1970
ity. Ju st as with any diagnostic tool, the p ractitio n er m ust have clinical experience with transillum i nation to achieve its greatest potential.
Laboratory phase T he study was divided into a laboratory phase and a clinical phase. D uring laboratory experim enta tion, hum an teeth w ere set in m odeling clay and p laster blocks and the effects of light intensity, light placem ent, disclosing solution, and colored and polarized filters w ere observed. E xtracted teeth w ith know n carious lesions were exam ined. A fiber optic bundle 1/8 inch in diam eter, illum i nated by a 150-w att projection light source was used to transillum inate each tooth. A n observa tion was then m ade as to w hat effect varying these factors has on the visual qualities achieved for the diagnosis o f caries. T he effect of transillum ination on an extracted central incisor that has a large area o f proxim al decay is shown in F ig u re 3; F igure 3, left, shows the tooth u nder norm al illum ination. Figure 3, center, shows the same tooth transillum inated from the lingual side; the area of underm ined tooth structure is outlined by the black arrow s, w hereas the w hite arrow s denote cervical decay th at may also be seen in F igure 3, left. Figure 3, right, is a radiograph o f the sam e tooth for com parison.
In a sim ilar m anner, F igure 4, left, shows an extracted lower prem olar u n der norm al and tra n s illum inated conditions. In this instance the light source was positioned on the buccocervical root surface; note the area o f underm ined tooth stru c ture indicated by the arrow in Figure 4, center. Figure 4, right, is a radiograph of the sam e tooth for com parison. W ith use of the standardized arrangem ent d e scribed previously, light intensity was varied first. It was determ ined that for optim um disclosure o f decay the intensity required varies directly with the thickness of tooth structure. A ccordingly, anterior teeth require low er light levels than pos terio r teeth. In clinical practice, light intensity m ust be increased for observation of posterior proxim al decay; the reason for this will be dis cussed. A ny attem pt to increase light intensity b e yond an optim um level fo r a given tooth results in poor contrast o f decay w ith tooth structure and may even obliterate all indications of decay. Light position was next exam ined in the labo ratory setup. T he fiber optic light output was m oved circum ferentially, axially, and at different angles to the tooth. U nder these conditions, it was determ ined th at for an terio r teeth, light m ust be applied to the labial as well as lingual areas to be m ost effective. In this m anner proxim olingual decay can be observed in a m irror while light is applied labially. F o r proxim olabial decay, light
Fig 4 ■ Lower premolar under normal illum ination (left); transilluminated from buccocervical root surface—note area of undermined tooth structure at arrow (center); radiographic view (right). Friedman—Marcus: TRANSILLUMINATION WITH FIBER OPTICS ■ 803
and the light ou tp u t from the fiber bundles. N one o f these filters im proved visual qualities, however. In addition, polarized filters w ere interposed in a sim ilar m anner and observed with and w ithout another polarized filter; there was no im prove m ent in visual qualities.
C linical phase
Fig 5 ■ Fiber optics transilluminator unit: A, case; B, intensity control; C, disclosing solution; D, glass probe; E, fiber optics bundle; F, fan.
is applied lingually and decay is observed by d i rect vision. T he laboratory arrangem ent w hereby light was passed perpendicular to the coronal p o r tion o f teeth m ounted in plaster blocks proved in effective in locating decay in posterior teeth. A clinical technic was developed in which light is passed cervically through the gingiva, alveolar bone, root, and crown so th at decay can be o b served occlusally. U nder these conditions, in creased light intensity is required (Fig 2). D isclosing solution was used in both the labo ratory and clinical phase. A n iodine-based disclos ing solution was applied to all teeth before tran s illum ination. T his technic was found to offer some im provem ent in the visual observation o f decay by increasing the light opacity of certain carious lesions. It was believed th at visual properties m ight be im proved fu rther by the use o f colored or polarized filters. U n d er laboratory conditions, red, yellow, and blue filters w ere interposed betw een the tooth
T he clinical phase of this study was perform ed at New Y ork U niversity College of D entistry with clinic patients, dental students, and dental assis tants as subjects. Tw enty patients w ere examined. T eeth o f 12 of these 20 patients in which we found proxim al decay or other dental disease, interesting from the p o in t of view o f our study, will be d is cussed. ■ Material and equipm ent: Initially an A m er ican O ptical Com pany industrial-type, 150-w il lum inator with a fiber optic bundle 1/8 inch in diam eter was used for clinical application. L ater a sim ilar u n it o f the authors’ design was used (Fig 5). This u n it consists essentially o f a 150-w p ro jection bulb, a heat absorbing lens, a lam p inten sity control, a cooling fan, and a fiber optic bundle 1/16 inch in diam eter. T he authors’ unit had a glass probe designed so the distal end was contraangled for easy m anipulation in the posterior arch, with a rounded tip for patient com fort. This probe can be rem oved for sterilization and replaced easily. ■ Diagnostic procedure: The patient who is being exam ined for caries should first be given a
Fig 6 ■ Light probe is held on labiocervical area while lingual surface is viewed with m irror (left); light probe is held beyond cervical margin, touching gingiva, for posterior arch examination (right). 804 ■ JADA, Vol. 80, April 1970
Fig 7 ■ Lower incisor: A, mirror; B, light probe position, C, caries (top left); radiograph (top right); upper incisor: A, palatal gingiva; B, silicate restoration; C, caries (bottom left); radiograph (bottom right).
thorough prophylaxis; an iodine-based solution should be applied to all teeth. It was found that, in abo u t 5 0 % o f the teeth exam ined, caries could be m ade m ore opaque by use of a disclosing solution. T he operating room consisted o f a standard d en tal o p eratory that was darkened but n o t left in com plete darkness; a radiograph view er was left on to provide w orking illum ination. Light inten sity was set to medium (of a low, m edium , and high 150-w light source). The anterior segments o f both arches w ere first exam ined. T he probe was held on the linguocervical area and an observation was m ade by direct vision. N ext, the probe was held on the labiocervical area and the lingual su r face was view ed with a m irro r (Fig 6, left). F o r calculus exam ination the cervical th ird o f both the lingual and the labial surfaces was observed. F o r calculus detection no disclosing solution is n eed ed even when there is no stain; otherw ise the
diagnostic procedure is the sam e as for caries. The posterior m axillary and m andibular arches w ere next exam ined (Fig 6, right). A t this point the light intensity was raised to slightly less than high. It was determ ined th at fo r caries detection on posterior teeth the probe m ust actually tran s m it light through the gingival m argin, bone, and root surface through the root (occlusally) for use ful results. U nder this arrangem ent the light probe is placed apically past the cervical m argin, touch ing the gingiva. Proxim al decay is then observed occlusally as a shadow (Fig 2). It is know n that proxim al decay spreads along the dentinoenam el ju n ctio n 6; a shadow outline o f proxim al carious tooth structure is observed w hen decay is exam ined in this m anner. In m ost instances, the occlu sal shadow of proxim al decay shows m ore accu rately the degree o f underm ined carious tooth structure than the usual bitew ing radiograph.
Friedman—Marcus: TRANSILLUMINATION WITH FIBER OPTICS ■ 805
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Fig 8 ■ Upper incisor: A, palatal gingiva; B, amalgam restoration; C, secondary caries (left); (see Fig 7, bottom right, for radiograph); lower canine: A, mirror; B, light probe position; C, caries (cen ter); radiograph of lower canine (right).
■ Clinical results: D uring the study, photographs w ere taken w ith fib er optic transillum ination as the only source of illum ination. A periapical or bitew ing radiograph was taken to confirm each diagnosis and com pare the diagnostic value of
fiber optic transillum ination with that o f conven tional radiographs. Figure 7, top left, shows a lower lateral incisor th at is transillum inated with the light source in a labial position. The clinical procedure is shown
Fig 9 ■ Upper premolar, occlusal view: A, proximal caries; B, light probe position; C, occlusal sur face (top left); radiograph (top right); upper premolar, occlusal view: A, proximal caries; B, opera tor’s thumb; C, light probe position; D, canine; E, occlusal surface of premolar (bottom left); radio graph (bottom right). 806 ■ JADA, Vol. 80, April 1970
Fig 10 ■ Lower premolar: A, incipient caries; B, buccal surface, first premolar; C, buccal surface, second premolar; D, inlay; E, light probe (top left); radiograph (top right); lower molar, distal view: A, light probe; B, caries; C, mirror; D, buccal surface (bottom left); radiograph (bottom right).
in Figure 6, left. T he corresponding radiograph, Figure 7, right, confirm s o u r diagnosis. T here is one advantage of fiber optic transillum ination (FO T I) not readily shown in Figure 7, top left. This is the fact th at the light source can be posi tioned at several angles to the tooth and in this m anner can present an alm ost three-dim ensional picture o f caries penetration. This kind of infor m ation would norm ally be available only if more than one radiograph was taken. Figure 7, bottom left, shows a lingual view of an upp er central incisor transillum inated with the light source in a labial position. On the left is a large region o f proxim al decay. On the right is a silicate restoration. This photograph clearly shows the difference in light transm ission between d e cay, the silicate restoration, and sound tooth stru c ture. T he corresponding radiograph confirm s our diagnosis. H ow ever, in the radiograph (Fig 7, bottom right) it is som etim es difficult to differen tiate caries from a radiolucent restorative m ateri al. W ith F O T I this differential diagnosis is sim pli fied. Figure 8, left, shows the lingual aspect o f an u pper lateral incisor. T he tooth has been transil
lum inated from the labial side. This photograph shows an am algam restoration in the cingulum area with secondary decay along the cervical m ar gin o f the restoration. A diagnosis of this condi tion would be difficult to make from the rad io graph (Fig 7, bottom right) alone. W ith F O T I this condition is clearly observed. Figure 8, center, shows the lingual aspect o f a lower canine. The tooth has been transillum inated from the labial side. N ote the decay on the distal portion. The radiograph shown in Figure 8, right, confirm s our diagnosis. F igure 9, top left, shows an occlusal view o f an u p per prem olar. The light source is positioned in the buccocervical area as previously described. T he photograph shows proxim al caries on the distal side of the prem olar as viewed with F O T I. It shows the full extent o f caries penetration in a buccolingual as well as m esiodistal direction. As we see in the radiograph (Fig 9, top right) infor m ation of this type would be im possible to obtain from a standard bitewing radiograph. Figure 9, bottom left, shows the occlusal view o f an upper prem olar. The light source was posi tioned in the buccocervical area. T he photograph
Friedman—Marcus: TRANSILLUMINATION WITH FIBER OPTICS ■ 807
Fig 11 ■ Lower molar, lingual view: A, light probe position; B, mirror; C, occlusal amalgam resto ration; D, pit caries (top left); radiograph (top right); upper molar: A, incipient caries; B, operator's thumb; C, light probe position (bottom left); radiograph (bottom right).
shows that decay has penetrated into the enamel only, as com pared to Figure 9, top left, in which the decay has penetrated into dentin. T he radio graph (Fig 9, bottom right) confirm s o u r diagnosis. F igure 10, top left, shows incipient decay on the distal portion o f a low er prem olar. In this photograph the light source was positioned on the lingual side and the buccal aspect is view ed direct ly. If the X -ray angulation is poor, this condition can easily b e obscured.8 See Figure 10, top right, for the radiograph of this situation. F igure 10, bottom left, is a m irror view o f the distal portion of a low er second m olar. T he tooth contains an existing M O am algam restoration and the radiograph, Figure 10, bottom right, shows decay on the distal proxim al surface. T he dentist w ho treats such a condition usually thinks in terms o f rem oving the M O am algam filling and replac ing it w ith an M OD am algam filling. However, in this instance, com plete excavation o f decay and rem oval o f underm ined enam el resulted in a large reduction o f tooth structure, both buccal and lingual, and the restoration o f choice was an inlay. If the dentist had the benefit o f FOT1 he could observe, as in Figure 10, bottom left, the extent to which decay has underm ined the buccal and 808 ■ JADA, Vol. 80, April 1970
lingual tooth structure. This kind o f know ledge would perm it a better choice of arm am entarium . T he bitew ing radiograph (Fig 10, bottom right) shows that inform ation regarding buccal and lin gual extension o f decay is unavailable. Figure 11, top left, shows the decay on the lin gual side o f a lower first m olar. Because o f an existing occlusal am algam restoration, decay on the lingual side cannot be observed on a radio graph (Fig 11, top right). W ith use of m axim um intensity, F O T I has disclosed lingual pit caries by passing light from the buccal side around the radiopaque restoration through to the lingual side. Figure 11, bottom left, shows an area of incipi ent decay on the m esiobuccal surface of an upper first m olar. L ight was passed from palatal to buc cal aspects, and the light probe was positioned in the palatocervical area. The radiograph (Fig 11, bottom right) shows that an area of decay can be obscured by the superim position of enamel. W ith F O T I an area o f incipient decay can easily be detected. Figure 12, left, shows how calculus looks under F O T I. T he light intensity was set to low and light was passed from labial to lingual aspects. This photograph is a m irror view of the linguoanterior
Fig 12 ■ Lower anterior teeth, lingual view: A, mirror; B, light probe position—arrows denote calcu lus (left); deciduous molar: A, mirror; B, crown; C, abscess; D, light probe (center); radiograph (right).
region. Calculus is observed as darkened areas in the cervical third o f the teeth. N o disclosing solu tion was used. F igure 12, center, shows how F O T I was used as an aid in the diagnosis of a periapical or interradicular abscess in a deciduous m olar. The p a tient com plained of pain in the low er deciduous m olar region. C linically the surrounding gingival area appeared slightly reddened with no sign o f swelling or frank inflam m ation. A positive diag nosis could not be m ade from the radiograph (Fig 12, right). T he F O T I light pro b e was placed deep in the m ucobuccal fold. Light o f m axim um intensity was passed through the gingiva, alveolar bone, and root structure. On the lingual gingiva and mucous m em brane we observed a sharply circum scribed dark area shown in the m irro r in Figure 12, cen ter. T his is an area o f inflam m atory exudate. It has a low er index o f light transm ission and does not pass light in the sam e m anner as the surround ing healthy periodontium . W ith F O T I we were able to diagnose this condition before bony d e struction had progressed and before it becam e well defined on X -ray film.
Summary T ransillum ination can be m ade a m ore useful tool through the application o f fiber optics. T he tech nics described are based on im proving the identi fication o f proxim al caries, especially in posterior teeth, w here transillum ination was n o t feasible previously. F O T I also m akes it possible to detect calculus w ithout the use o f disclosing solutions. In addition, the study shows how F O T I can be used as an aid in diagnosing periapical or interradicular lesions. A dditional work in this area is still required. O ther potential applications for which FO TI
m ay aid in diagnosis are: O bserving cracks and fissures, vitality testing, subgingival calculus and food pockets, visualization of root canals in end odontic treatm ent, and sinus involvem ent. The desirability o f using F O T I as a diagnostic tool is that it is fast and requires no film process ing. It may be used in screening exam inations by auxiliary personnel. It is low in cost and can be used repeatedly w ithout radiation hazard. It is ideal as a field unit for exam ining invalids, for the arm ed forces, or in any application w here the use of a standard X -ray m achine w ould be im practical.
This article is based on the table clinic, “ Transillumina tion of Teeth Using Fiber Optics,” presented by J. Friedman at the 109th annual session of the American Dental Associ ation, Miami Beach, Fla, Oct 28, 1968. The authors wish to thank Arthur H. Morrison, chairman, department of operative dentistry, New York University College of Dentistry, for his cooperation in the preparation of this article. Doctor Friedman is assistant research scientist and Doc tor Marcus is associate professor of operative dentistry, New York University College of Dentistry, 421 First Ave, New York, 10010.
1. Fiber optics light wires—application bulletin. Roches ter, NY, Bausch and Lomb, Glass Fiber Optics Division. 2. Designing with Crofon light guides. W ilmington, Del, E. I. DuPont de Nemours and Co., Inc., Plastics dept. 3. Taylor, R.C.; Ware, W.H.; and McDowell, J.A. Illum ina tion of the oral cavity. JADA 74:1207 May 1967. 4. Baurmash, H., and Mandel, L. Fiber optic lighting in oral surgery. NY Dent J 35:29 Jan 1969. 5. Cameron, W.J. Diagnosis by transillum ination. Chi cago, Cameron's Publishing Co., 1927. 6. Tiecke, R.W.; Stutevilie, O.H.; and Calandra, J.C. Pathologic physiology of oral disease. St. Louis, C. V. Mosby Co., 1959, p 402. 7. McGehee, W.H.O.; True, H.A.; and Inskipp, E.F. A textbook of operative dentistry, ed 4. New York, McGrawHill, 1956, p 45. 8. Wuehrmann, A.H., and Manson-Hing, L.R. Dental radiology. St. Louis, C. V. Mosby Co., 1965, p 257.
Friedman—Marcus: TRANSILLUMINATION WITH FIBER OPTICS ■ 809
Joshua Friedman, BEE, DDS Morton I. Marcus, DDS, New York
Fiber optics applied to transillum ination of teeth and other oral structures is a useful technic for de tection of caries, calculus, and soft tissue lesions. It permits a cold, high-intensity light source to be used anywhere in the oral cavity w ith ease and fle x i b ility. It often shows the degree of undermined carious tooth structure more accurately than the usual bitewing radiograph, and may aid in diagno sis of periapical and periodontal abscesses before bony destruction has occurred or swelling is ap parent.
This article describes the application of fiber optic transillum ination as a diagnostic tool for the iden tification o f caries, calculus, and soft tissue lesions in the oral cavity. F ib er optic transillum ination is particularly useful in locating decay on the p ro xi mal areas o f teeth in the posterior as well as an te rior parts of the m outh. I t is also useful for caries detection anyw here in the m outh where proxim al decay is adjacent to a radiopaque restoration, or where buccolingual decay exists in a tooth con taining a radiopaque occlusal restoration.
m itted to the other end by a process o f total in ternal reflection as shown in Figure 1. In the p ro cess o f internal reflection each fiber is clad w ith a refractive layer so that light w hich strikes the in side wall o f the fiber is reflected internally. In this m anner light can be transm itted with high effi ciency. Since applications for a single fiber are no t practical, large num bers of fibers (from 64 to 1 m illion) are clustered together to form a single bundle, ranging from 1/16 inch to 1/4 inch in d i am eter and several feet in length. In the past, fiber optics has been used in the oral cavity to provide intense illum ination of the dental operating field.3-4 F ib er optics, as we have applied it, is used as a diagnostic tool fo r the p u r pose o f transillum ination o f teeth and other oral structures. ■ Transillumination: Transillum ination, the p a s sage o f light through teeth and tissue, is n o t in
fiber optic bundle
■ Fiber optics: F ib er optics is a term given to thin cylindrical fibers o f glass o r plastic of high optical quality. A single fiber resem bling a strand of thread is often as sm all as 10/a1 (0.01 mils) in diam eter fo r the glass variety and 10 mils for plas tic.2 Light entering one end o f the fiber is trans
801
tran s Illu m in a to r
proximal decay
probe
shadow of proximal decay in enamel
shadow of proximal
decay in d e n tin
Fig 2 ■ Proximal decay on posterior teeth is observed as occlusal shadow in fiber optics transillum ination.
itself a new developm ent.5 T he principle o f tran s illum ination o f teeth is simple. It w orks because o f the different index of light transm ission for d e cay, calculus, restorative m aterials, sound tooth structure, inflam m atory exudate, and healthy periodontium . Since tooth decay has a lower in dex o f light transm ission than sound tooth struc ture, an area of decay shows up as a darkened shadow th at follows the spread o f decay along the path o f dentinal tubules6 (Fig 2). Calculus shows up as a darkened region involving the cervical th ird o f teeth. Periapical and periodontal ab scesses m ay also be diagnosed with use of fiber
optic transillum ination. A diagnosis of these co n ditions can som etim es be m ade at an early stage, at a point w here no bony destruction has occurred, w here swelling m ay not be apparent, and where a diagnosis based on a radiograph alone would be difficult.7 U nder conditions o f tissue inflam m ation w here an inflam m atory exudate exists, highly in tense light can be passed through the gingiva, root, and alveolar bone. A n abscess or any acute tissue inflam m ation shows up as a sharply circum scribed area of dim inished light transm ission.5 T his occurs because o f the buildup o f inflam m a tory exudate w hich again has an index of light transm ission lower than the surrounding area of healthy tissue. In a sim ilar m anner, translucent re storative m aterials, all of which have a different index o f light transm ission, can be differentiated from sound o r decayed tooth structure. F o r m any years, light was used in the anterior p art o f the m outh for detection o f caries. H ow ever, its use was discontinued by many dentists b e cause the lam ps w ere too bulky to be used easily in the posterior p art of the m outh. They w ere u n com fortable to the patient because they gave off too m uch heat; or else they did not produce suf ficient light ou tp u t to be used effectively. F ib er o p tics extends the range o f transillum ination. It p e r m its a cold, high-intensity light source to be used anyw here in the oral cavity with ease and flexibil
Fig 3 ■ Central incisor under normal illu m in a tio n (le ft); tra n sillu m in a te d from lingual side—black arrows in d ica te underm ined tooth structure, w h ite arrows show cervical decay (center); radiographic view (right).
802 ■ JADA, Vol. 80, April 1970
ity. Ju st as with any diagnostic tool, the p ractitio n er m ust have clinical experience with transillum i nation to achieve its greatest potential.
Laboratory phase T he study was divided into a laboratory phase and a clinical phase. D uring laboratory experim enta tion, hum an teeth w ere set in m odeling clay and p laster blocks and the effects of light intensity, light placem ent, disclosing solution, and colored and polarized filters w ere observed. E xtracted teeth w ith know n carious lesions were exam ined. A fiber optic bundle 1/8 inch in diam eter, illum i nated by a 150-w att projection light source was used to transillum inate each tooth. A n observa tion was then m ade as to w hat effect varying these factors has on the visual qualities achieved for the diagnosis o f caries. T he effect of transillum ination on an extracted central incisor that has a large area o f proxim al decay is shown in F ig u re 3; F igure 3, left, shows the tooth u nder norm al illum ination. Figure 3, center, shows the same tooth transillum inated from the lingual side; the area of underm ined tooth structure is outlined by the black arrow s, w hereas the w hite arrow s denote cervical decay th at may also be seen in F igure 3, left. Figure 3, right, is a radiograph o f the sam e tooth for com parison.
In a sim ilar m anner, F igure 4, left, shows an extracted lower prem olar u n der norm al and tra n s illum inated conditions. In this instance the light source was positioned on the buccocervical root surface; note the area o f underm ined tooth stru c ture indicated by the arrow in Figure 4, center. Figure 4, right, is a radiograph of the sam e tooth for com parison. W ith use of the standardized arrangem ent d e scribed previously, light intensity was varied first. It was determ ined that for optim um disclosure o f decay the intensity required varies directly with the thickness of tooth structure. A ccordingly, anterior teeth require low er light levels than pos terio r teeth. In clinical practice, light intensity m ust be increased for observation of posterior proxim al decay; the reason for this will be dis cussed. A ny attem pt to increase light intensity b e yond an optim um level fo r a given tooth results in poor contrast o f decay w ith tooth structure and may even obliterate all indications of decay. Light position was next exam ined in the labo ratory setup. T he fiber optic light output was m oved circum ferentially, axially, and at different angles to the tooth. U nder these conditions, it was determ ined th at for an terio r teeth, light m ust be applied to the labial as well as lingual areas to be m ost effective. In this m anner proxim olingual decay can be observed in a m irror while light is applied labially. F o r proxim olabial decay, light
Fig 4 ■ Lower premolar under normal illum ination (left); transilluminated from buccocervical root surface—note area of undermined tooth structure at arrow (center); radiographic view (right). Friedman—Marcus: TRANSILLUMINATION WITH FIBER OPTICS ■ 803
and the light ou tp u t from the fiber bundles. N one o f these filters im proved visual qualities, however. In addition, polarized filters w ere interposed in a sim ilar m anner and observed with and w ithout another polarized filter; there was no im prove m ent in visual qualities.
C linical phase
Fig 5 ■ Fiber optics transilluminator unit: A, case; B, intensity control; C, disclosing solution; D, glass probe; E, fiber optics bundle; F, fan.
is applied lingually and decay is observed by d i rect vision. T he laboratory arrangem ent w hereby light was passed perpendicular to the coronal p o r tion o f teeth m ounted in plaster blocks proved in effective in locating decay in posterior teeth. A clinical technic was developed in which light is passed cervically through the gingiva, alveolar bone, root, and crown so th at decay can be o b served occlusally. U nder these conditions, in creased light intensity is required (Fig 2). D isclosing solution was used in both the labo ratory and clinical phase. A n iodine-based disclos ing solution was applied to all teeth before tran s illum ination. T his technic was found to offer some im provem ent in the visual observation o f decay by increasing the light opacity of certain carious lesions. It was believed th at visual properties m ight be im proved fu rther by the use o f colored or polarized filters. U n d er laboratory conditions, red, yellow, and blue filters w ere interposed betw een the tooth
T he clinical phase of this study was perform ed at New Y ork U niversity College of D entistry with clinic patients, dental students, and dental assis tants as subjects. Tw enty patients w ere examined. T eeth o f 12 of these 20 patients in which we found proxim al decay or other dental disease, interesting from the p o in t of view o f our study, will be d is cussed. ■ Material and equipm ent: Initially an A m er ican O ptical Com pany industrial-type, 150-w il lum inator with a fiber optic bundle 1/8 inch in diam eter was used for clinical application. L ater a sim ilar u n it o f the authors’ design was used (Fig 5). This u n it consists essentially o f a 150-w p ro jection bulb, a heat absorbing lens, a lam p inten sity control, a cooling fan, and a fiber optic bundle 1/16 inch in diam eter. T he authors’ unit had a glass probe designed so the distal end was contraangled for easy m anipulation in the posterior arch, with a rounded tip for patient com fort. This probe can be rem oved for sterilization and replaced easily. ■ Diagnostic procedure: The patient who is being exam ined for caries should first be given a
Fig 6 ■ Light probe is held on labiocervical area while lingual surface is viewed with m irror (left); light probe is held beyond cervical margin, touching gingiva, for posterior arch examination (right). 804 ■ JADA, Vol. 80, April 1970
Fig 7 ■ Lower incisor: A, mirror; B, light probe position, C, caries (top left); radiograph (top right); upper incisor: A, palatal gingiva; B, silicate restoration; C, caries (bottom left); radiograph (bottom right).
thorough prophylaxis; an iodine-based solution should be applied to all teeth. It was found that, in abo u t 5 0 % o f the teeth exam ined, caries could be m ade m ore opaque by use of a disclosing solution. T he operating room consisted o f a standard d en tal o p eratory that was darkened but n o t left in com plete darkness; a radiograph view er was left on to provide w orking illum ination. Light inten sity was set to medium (of a low, m edium , and high 150-w light source). The anterior segments o f both arches w ere first exam ined. T he probe was held on the linguocervical area and an observation was m ade by direct vision. N ext, the probe was held on the labiocervical area and the lingual su r face was view ed with a m irro r (Fig 6, left). F o r calculus exam ination the cervical th ird o f both the lingual and the labial surfaces was observed. F o r calculus detection no disclosing solution is n eed ed even when there is no stain; otherw ise the
diagnostic procedure is the sam e as for caries. The posterior m axillary and m andibular arches w ere next exam ined (Fig 6, right). A t this point the light intensity was raised to slightly less than high. It was determ ined th at fo r caries detection on posterior teeth the probe m ust actually tran s m it light through the gingival m argin, bone, and root surface through the root (occlusally) for use ful results. U nder this arrangem ent the light probe is placed apically past the cervical m argin, touch ing the gingiva. Proxim al decay is then observed occlusally as a shadow (Fig 2). It is know n that proxim al decay spreads along the dentinoenam el ju n ctio n 6; a shadow outline o f proxim al carious tooth structure is observed w hen decay is exam ined in this m anner. In m ost instances, the occlu sal shadow of proxim al decay shows m ore accu rately the degree o f underm ined carious tooth structure than the usual bitew ing radiograph.
Friedman—Marcus: TRANSILLUMINATION WITH FIBER OPTICS ■ 805
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Fig 8 ■ Upper incisor: A, palatal gingiva; B, amalgam restoration; C, secondary caries (left); (see Fig 7, bottom right, for radiograph); lower canine: A, mirror; B, light probe position; C, caries (cen ter); radiograph of lower canine (right).
■ Clinical results: D uring the study, photographs w ere taken w ith fib er optic transillum ination as the only source of illum ination. A periapical or bitew ing radiograph was taken to confirm each diagnosis and com pare the diagnostic value of
fiber optic transillum ination with that o f conven tional radiographs. Figure 7, top left, shows a lower lateral incisor th at is transillum inated with the light source in a labial position. The clinical procedure is shown
Fig 9 ■ Upper premolar, occlusal view: A, proximal caries; B, light probe position; C, occlusal sur face (top left); radiograph (top right); upper premolar, occlusal view: A, proximal caries; B, opera tor’s thumb; C, light probe position; D, canine; E, occlusal surface of premolar (bottom left); radio graph (bottom right). 806 ■ JADA, Vol. 80, April 1970
Fig 10 ■ Lower premolar: A, incipient caries; B, buccal surface, first premolar; C, buccal surface, second premolar; D, inlay; E, light probe (top left); radiograph (top right); lower molar, distal view: A, light probe; B, caries; C, mirror; D, buccal surface (bottom left); radiograph (bottom right).
in Figure 6, left. T he corresponding radiograph, Figure 7, right, confirm s o u r diagnosis. T here is one advantage of fiber optic transillum ination (FO T I) not readily shown in Figure 7, top left. This is the fact th at the light source can be posi tioned at several angles to the tooth and in this m anner can present an alm ost three-dim ensional picture o f caries penetration. This kind of infor m ation would norm ally be available only if more than one radiograph was taken. Figure 7, bottom left, shows a lingual view of an upp er central incisor transillum inated with the light source in a labial position. On the left is a large region o f proxim al decay. On the right is a silicate restoration. This photograph clearly shows the difference in light transm ission between d e cay, the silicate restoration, and sound tooth stru c ture. T he corresponding radiograph confirm s our diagnosis. H ow ever, in the radiograph (Fig 7, bottom right) it is som etim es difficult to differen tiate caries from a radiolucent restorative m ateri al. W ith F O T I this differential diagnosis is sim pli fied. Figure 8, left, shows the lingual aspect o f an u pper lateral incisor. T he tooth has been transil
lum inated from the labial side. This photograph shows an am algam restoration in the cingulum area with secondary decay along the cervical m ar gin o f the restoration. A diagnosis of this condi tion would be difficult to make from the rad io graph (Fig 7, bottom right) alone. W ith F O T I this condition is clearly observed. Figure 8, center, shows the lingual aspect o f a lower canine. The tooth has been transillum inated from the labial side. N ote the decay on the distal portion. The radiograph shown in Figure 8, right, confirm s our diagnosis. F igure 9, top left, shows an occlusal view o f an u p per prem olar. The light source is positioned in the buccocervical area as previously described. T he photograph shows proxim al caries on the distal side of the prem olar as viewed with F O T I. It shows the full extent o f caries penetration in a buccolingual as well as m esiodistal direction. As we see in the radiograph (Fig 9, top right) infor m ation of this type would be im possible to obtain from a standard bitewing radiograph. Figure 9, bottom left, shows the occlusal view o f an upper prem olar. The light source was posi tioned in the buccocervical area. T he photograph
Friedman—Marcus: TRANSILLUMINATION WITH FIBER OPTICS ■ 807
Fig 11 ■ Lower molar, lingual view: A, light probe position; B, mirror; C, occlusal amalgam resto ration; D, pit caries (top left); radiograph (top right); upper molar: A, incipient caries; B, operator's thumb; C, light probe position (bottom left); radiograph (bottom right).
shows that decay has penetrated into the enamel only, as com pared to Figure 9, top left, in which the decay has penetrated into dentin. T he radio graph (Fig 9, bottom right) confirm s o u r diagnosis. F igure 10, top left, shows incipient decay on the distal portion o f a low er prem olar. In this photograph the light source was positioned on the lingual side and the buccal aspect is view ed direct ly. If the X -ray angulation is poor, this condition can easily b e obscured.8 See Figure 10, top right, for the radiograph of this situation. F igure 10, bottom left, is a m irror view o f the distal portion of a low er second m olar. T he tooth contains an existing M O am algam restoration and the radiograph, Figure 10, bottom right, shows decay on the distal proxim al surface. T he dentist w ho treats such a condition usually thinks in terms o f rem oving the M O am algam filling and replac ing it w ith an M OD am algam filling. However, in this instance, com plete excavation o f decay and rem oval o f underm ined enam el resulted in a large reduction o f tooth structure, both buccal and lingual, and the restoration o f choice was an inlay. If the dentist had the benefit o f FOT1 he could observe, as in Figure 10, bottom left, the extent to which decay has underm ined the buccal and 808 ■ JADA, Vol. 80, April 1970
lingual tooth structure. This kind o f know ledge would perm it a better choice of arm am entarium . T he bitew ing radiograph (Fig 10, bottom right) shows that inform ation regarding buccal and lin gual extension o f decay is unavailable. Figure 11, top left, shows the decay on the lin gual side o f a lower first m olar. Because o f an existing occlusal am algam restoration, decay on the lingual side cannot be observed on a radio graph (Fig 11, top right). W ith use of m axim um intensity, F O T I has disclosed lingual pit caries by passing light from the buccal side around the radiopaque restoration through to the lingual side. Figure 11, bottom left, shows an area of incipi ent decay on the m esiobuccal surface of an upper first m olar. L ight was passed from palatal to buc cal aspects, and the light probe was positioned in the palatocervical area. The radiograph (Fig 11, bottom right) shows that an area of decay can be obscured by the superim position of enamel. W ith F O T I an area o f incipient decay can easily be detected. Figure 12, left, shows how calculus looks under F O T I. T he light intensity was set to low and light was passed from labial to lingual aspects. This photograph is a m irror view of the linguoanterior
Fig 12 ■ Lower anterior teeth, lingual view: A, mirror; B, light probe position—arrows denote calcu lus (left); deciduous molar: A, mirror; B, crown; C, abscess; D, light probe (center); radiograph (right).
region. Calculus is observed as darkened areas in the cervical third o f the teeth. N o disclosing solu tion was used. F igure 12, center, shows how F O T I was used as an aid in the diagnosis of a periapical or interradicular abscess in a deciduous m olar. The p a tient com plained of pain in the low er deciduous m olar region. C linically the surrounding gingival area appeared slightly reddened with no sign o f swelling or frank inflam m ation. A positive diag nosis could not be m ade from the radiograph (Fig 12, right). T he F O T I light pro b e was placed deep in the m ucobuccal fold. Light o f m axim um intensity was passed through the gingiva, alveolar bone, and root structure. On the lingual gingiva and mucous m em brane we observed a sharply circum scribed dark area shown in the m irro r in Figure 12, cen ter. T his is an area o f inflam m atory exudate. It has a low er index o f light transm ission and does not pass light in the sam e m anner as the surround ing healthy periodontium . W ith F O T I we were able to diagnose this condition before bony d e struction had progressed and before it becam e well defined on X -ray film.
Summary T ransillum ination can be m ade a m ore useful tool through the application o f fiber optics. T he tech nics described are based on im proving the identi fication o f proxim al caries, especially in posterior teeth, w here transillum ination was n o t feasible previously. F O T I also m akes it possible to detect calculus w ithout the use o f disclosing solutions. In addition, the study shows how F O T I can be used as an aid in diagnosing periapical or interradicular lesions. A dditional work in this area is still required. O ther potential applications for which FO TI
m ay aid in diagnosis are: O bserving cracks and fissures, vitality testing, subgingival calculus and food pockets, visualization of root canals in end odontic treatm ent, and sinus involvem ent. The desirability o f using F O T I as a diagnostic tool is that it is fast and requires no film process ing. It may be used in screening exam inations by auxiliary personnel. It is low in cost and can be used repeatedly w ithout radiation hazard. It is ideal as a field unit for exam ining invalids, for the arm ed forces, or in any application w here the use of a standard X -ray m achine w ould be im practical.
This article is based on the table clinic, “ Transillumina tion of Teeth Using Fiber Optics,” presented by J. Friedman at the 109th annual session of the American Dental Associ ation, Miami Beach, Fla, Oct 28, 1968. The authors wish to thank Arthur H. Morrison, chairman, department of operative dentistry, New York University College of Dentistry, for his cooperation in the preparation of this article. Doctor Friedman is assistant research scientist and Doc tor Marcus is associate professor of operative dentistry, New York University College of Dentistry, 421 First Ave, New York, 10010.
1. Fiber optics light wires—application bulletin. Roches ter, NY, Bausch and Lomb, Glass Fiber Optics Division. 2. Designing with Crofon light guides. W ilmington, Del, E. I. DuPont de Nemours and Co., Inc., Plastics dept. 3. Taylor, R.C.; Ware, W.H.; and McDowell, J.A. Illum ina tion of the oral cavity. JADA 74:1207 May 1967. 4. Baurmash, H., and Mandel, L. Fiber optic lighting in oral surgery. NY Dent J 35:29 Jan 1969. 5. Cameron, W.J. Diagnosis by transillum ination. Chi cago, Cameron's Publishing Co., 1927. 6. Tiecke, R.W.; Stutevilie, O.H.; and Calandra, J.C. Pathologic physiology of oral disease. St. Louis, C. V. Mosby Co., 1959, p 402. 7. McGehee, W.H.O.; True, H.A.; and Inskipp, E.F. A textbook of operative dentistry, ed 4. New York, McGrawHill, 1956, p 45. 8. Wuehrmann, A.H., and Manson-Hing, L.R. Dental radiology. St. Louis, C. V. Mosby Co., 1965, p 257.
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