From the Bergen County Medical Examiner’s Office, Paramus, NJ.
Manuscript received June 13, 2011; accepted September 27, 2011.
The authors report no conflicts of interest.
Reprints: Gerald Guzy, DDS, 492 Hensler Lane Oradell, NJ 07649. E-mail: email@example.com.
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Abstract: With the increased use of composite resin and the decreased use of amalgam as a dental restorative material, the forensic dental identification of unidentified human remains has become more difficult. Various methods have been used to detect the presence of composite resin restorations including dyes, forensic alternative light sources, quantitative light-induced fluorescence, and ultraviolet lights. Although these methods may be helpful, the expense of the equipment, the electrical requirements, and the need for water to wash the dye from the mouth may make these methods impractical especially in a temporary morgue situation during a mass disaster. The fluorescent properties of composite resins, when exposed to ultraviolet light, are well documented. Standard tube ultraviolet lights have been used to detect the presence of composite resin, but these lights are large and bulky, and the tubes are fragile. The development of ultraviolet light emitting diode flashlights has provided forensic odontologists with a tool that is small, inexpensive, and battery operated. The two forensic dental identification cases described here demonstrate the value of ultraviolet light emitting diode flashlights as an adjunct to a careful clinical and radiographic examination.
According to the American Dental Association, the number of posterior composite resin restorations placed by all private practitioners in 1990 was estimated to be 13,860,000.1 By 1999, that number had increased by more than 300% to 46,116,000.2 The decrease in the use of amalgam as a dental restorative material for posterior teeth and the significant increase in the use of composite resin in the posterior teeth will undoubtedly complicate the forensic dental identification of human remains. This increase can be attributed to the fact that dentists are doing more conservative restorations, that the adhesives that bond the composites to the dentin and enamel are now producing higher bond strengths, and that color stability and wear resistance have been improved.3 Patients are more aware that there are “white fillings” available, and they are requesting them.
Determining the presence of an amalgam restoration during the postmortem clinical examination, even in dentitions involved in fires, is relatively easy. Because the shade of the composite restoration often matches the tooth so closely, it can be overlooked during the postmortem clinical examination. The radiolucency or radiopacity of a particular composite resin is determined by the manufacturer. Resin-based composites may have radiographic properties similar to dentin or enamel, making them difficult to detect during the postmortem radiographic examination. Complicating this is the fact that the forensic odontologist may be performing the identification in a location that he or she is not familiar with such as a funeral home or a temporary morgue in a tent or warehouse. In these locations, access to water and sources of electricity may be limited, making visualization and the ability to thoroughly clean and dry the dentition more difficult.
Researchers have used various methods to detect the presence of composite resins restorative materials. Midda4 (1969) reported that a 0.2% brilliant green solution was used as a disclosing solution to identify synthetic fillings in forensic dental identifications. Clark and Ruddick5 (1985) used long-wave ultraviolet radiation and found that, of 27 composite-filled teeth, “22 were readily observed by ultraviolet absorption and 5 by differential fluorescence.” Clark (1989) also compared ultraviolet and near-infrared wave lengths and found that “composite detection by infrared is less satisfactory than by ultraviolet radiation.”6 Carson et al7 (1997) used a Polilight PL10 (Rofin Australia Pty Ltd, Melbourne, Australia) light to detect white restorative dental materials. The Polilight PL10 is a forensic alternative light source with 9 different wavelengths from 315 to 650 nm. He concluded that “a commercially available forensic alternate light source greatly facilitates identification of tooth colored restorative dental materials.” However, the Polilight PL10 has been replaced by the PL500 model and sells for approximately $17,000. Pretty8 (2003) used the technique of quantitative light-induced fluorescence (QLF) to identify composite restorations. His results showed that QLF (Inspektor Research Systems BV, Amsterdam, The Netherlands) examination “significantly increases the detection of composite restorations.” The QLF instrument required the use of a light source, intraoral camera, computer, monitor, and special software and sold for approximately $24,000. Kazutoshi (2003) was able to show that by attaching filters of different wavelengths to a halogen light curing unit (Jetlight 3000; J. Morita USA, Irvine, Calif), discrimination between teeth and composite resin using their fluorescent properties was possible.9 Several of the research projects showed the potential of using ultraviolet lights for the detection of composite resin restorations during the postmortem forensic dental examination.
The fluorescent properties of dental porcelain and composite resin are well documented.10–13 The fluorescence of dental porcelain is due to the inclusion of rare earth compounds such as europium, ytterbium, and samarium. The fluorescence of composite resin may also be due to the inclusion of rare earth compounds in the filler component or organic compounds in the resin matrix portion.14 However, manufacturers consider this to be proprietary information. When exposed to ultraviolet light, composite resin may fluoresce more than the surrounding tooth and appear brighter than the surrounding tooth. If the composite resin material has little or no fluorescing agents, it may appear dark when exposed to ultraviolet light. The natural fluorescence of the surrounding tooth will contrast with the darker-appearing composite resin. In both instances, it is the contrast between tooth and composite resin that is the basis for detecting composite resin restorations during forensic dental identifications.
Ultraviolet lights are commonly in the form of tubes or bulbs similar to fluorescent light bulbs and can be as small as 6 in. or as long as 24 in. Most of these lights have power cords that require the availability of an electrical outlet. The tube-type lights do not project the ultraviolet light in a forward direction, which makes them difficult to aim at the unidentified remains being examined. There are also lantern-type ultraviolet lights that can direct the beam in a forward direction, but the beam is very intense, making them more applicable for forensic scanning of an entire room rather than a small intraoral space. The lantern-type lights are bulky and can weigh up to 4 pounds, making them difficult to maneuver. These lights are mostly battery powered by rechargeable battery packs that still require the availability of an electrical outlet. With both the tube type and the lantern type of ultraviolet lights, there is the risk of breaking the glass tube or bulb. Because the size, weight, electrical requirements, and fragility of the ultraviolet bulbs and tube-type and lantern-type lights are not always practical for use in forensic dental examinations.
The ideal ultraviolet light for forensic dental identification use would meet 4 criteria:
1. Inexpensive—so that it can be purchased by any individual who does not have the financial resources of a government agency.
2. Small and lightweight—a light that can fit in a jacket or pants pocket and stored in a forensic kit.
3. Battery operated—so that it is not necessary to locate a source of electricity or to use long extension cords.
4. Effectiveness—the most important criterion is that it must be of value in detecting composite resin restorations.
The development of ultraviolet light emitting diodes (UV LED) in the late 1990s led to the development of UV LED flashlights. Although there are many UV LED flashlights, the Inova X5 UV LED flashlight (Figs. 1 and 2; Emmissive Energy Corp, N. Kingstown, RI) meets the first 3 criteria:
1. Inexpensive—approximately $40.
2. Small and lightweight—12 cm long by 2 cm in diameter and 110 g.
3. Battery operated—2, 3 V lithium batteries powering 5 UV LEDs at approximately 395 nm.
The goal of this study was to determine if the Inova X5 UV LED flashlight could meet the fourth and most important criterion, effectiveness in detecting composite resin restorations, by testing the light during the forensic dental examination of 2 cases of unidentified human remains.
In case 1 (Figs. 3–5), the decomposed remains of an adult were found by hikers in a densely wooded area. Fingerprints were obtained, but there was no match in the databases. The resected maxilla and mandible were examined, charted, and radiographed then re-examined using the Inova X5 UV LED flashlight. Each arch was photographed using overhead fluorescent lighting and then photographed while illuminated with the Inova X5 UV LED flashlight. Composite resin restorations were detected in teeth numbers 3, 4, 8, 9, 14, 17, and 31 using the Inova X5 UV LED flashlight. In addition, a porcelain fused to metal crown on tooth number 30 was detected with the UV LED light and was confirmed radiographically. The comparison of antemortem and postmortem dental records and radiographs confirmed the presence of the composite resin restorations that were detected by the Inova X5 UV LED flashlight. Case number 1 was a positive forensic dental identification.
In case 2 (Figs. 6 and 7), the severely burned remains of an adult were discovered in a house that had been totally destroyed by fire. Fingerprints were not obtainable from the remains. The resected maxilla and mandible were examined, charted, and radiographed then re-examined using the Inova X5 UV LED flashlight. Each arch was photographed using overhead fluorescent lighting and then photographed while illuminated with the Inova UV LED flashlight. Composite resin restorations were detected in teeth numbers 3, 7, 8, 9, 13, 14, and 19 using the Inova X5 UV LED flashlight. In addition, a porcelain fused to metal crown on tooth number 10 was detected with the UV LED light and was confirmed radiographically. The comparison of antemortem and postmortem dental records and radiographs confirmed the presence of the composite resin restorations that were detected by the Inova X5 UV LED flashlight. Case 2 was a positive forensic dental identification.
The two forensic dental identification cases presented here demonstrate the value of using a small, inexpensive, battery-operated UV LED flashlight during forensic dental identifications. In both cases, porcelain crowns were also clearly identified because of their fluorescent properties. The use of UV LED flashlights are not intended to be a substitute but an adjunct to a detailed postmortem examination and high-quality postmortem radiographs.
With the increased use of composite resin, UV LED flashlights can be a valuable aid in detecting the presence of composite resin restorations that may be overlooked during the postmortem visual and radiographic examinations.
1. Calculated from American Dental Association, Survey Center, 1990 Survey of Dental Services Rendered and Distribution of Dentists in the US by Region and State, 1991 Table 11: Estimation of Dental Services Completed in 1990 by Private Practitioners by Dental Specialty.
2. Calculated from America Dental Association, Survey Center, 2005–06 Survey of Dental Services Rendered and Distribution of Dentists in the United States by Region and State, 2005 Table 35: Annual Estimates of Restorative Procedures Completed by Private Practitioners, by Dental Specialty, 2005-06.
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