The Fluorescence-aided Identification Technique is a practicable, fast, and reliable approach for the differentiation of composite resin restorations from tooth substance, and facilitates the minimally invasive and complete removal of composite resin restorations and composite bonded trauma splints.
The detection and removal of tooth-colored filling materials is a major challenge for every dentist. The Fluorescence-aided Identification Technique (FIT) is a noninvasive tool to facilitate the distinction of composite resin material from sound tooth substance. Compared to conventional illumination, FIT is a very accurate, reliable, and fast diagnostic method. When composite resin is illuminated with a wavelength of approximately 398 ± 5 nm, certain fluorescent components make the composite resin appear brighter than the tooth structure. Any fluorescence-inducing light source with the appropriate wavelength can be used for this method. Optimally, this technique is used without additional natural or artificial lighting. The application of FIT can be used for diagnostic purposes, for example, dental charts, and additionally for the complete and minimally invasive removal of composite resin restorations, bracket debonding, and trauma splint removal. The assessment of volumetric changes after composite removal can be provided by overlapping pre- and postoperative scans and subsequent calculation using suitable software.
The application of FIT facilitates the distinction of composite resin materials from sound tooth substance compared to conventional illumination, for example, by a dental unit lamp1,2. Fluorescence occurs when a material emits the light at a higher wavelength than it has been absorbed. As a result of this illumination, the material appears brighter than the tooth3. The maximum fluorescence of composite resin materials occurs when illuminated by a wavelength of 398 ± 5 nanometers3. Fluorescence in composite resin materials appears due to rare earth oxides added to the glass fillers, some of the main components of composite resins4,5. The addition of these fluorescent substances intends to adapt the optical properties of composite resins to the tooth structure to improve the esthetic properties of composite resins4,5. FIT is applicable on many composite resin materials as they show these fluorescence properties3. However, fluorescence decreases with the ageing of the composite resin materials6,7,8,9.
The distinguishment of composite resin materials from tooth structure with conventional illumination is a challenge since modern composite resin materials match the optical properties of tooth substance almost perfectly10,11. The misdiagnosis of composite resin results in inaccurate dental charts, false caries risk assessment, and inappropriate treatment planning11. Moreover, epidemiological data is falsified12.
Composite resin is the material of choice for direct restorations due to its straightforward handling, esthetic properties, and clinical performance13. Nevertheless, many composite restorations must be renewed due to secondary caries, fractures, or other reasons14,15. However, the removal of residual composite resin materials can be demanding under conventional light conditions. Even with the application of a magnification aid and the use of tactile probes or extensive drying of the teeth, composite residues are sometimes difficult to distinguish from sound tooth structure. Leftovers of composite remnants during the removal of the adhesive restoration lower the quality of further restorations and have an esthetic impairment due to possible discoloration of the margins1,16,17,18,19,20,21,22. On the contrary, an overpreparation due to misdiagnosis of composite resin versus tooth structure may result in unnecessary substance loss1,2.
In dental traumatology, fixation of the injured teeth using trauma splints is frequent and mandatory in many cases23. The trauma splints are usually fixed on the teeth using a flowable composite resin material. Incomplete removal of the composite resin material in this scenario may lead to the impairments described above. Since dental trauma occurs mostly in front teeth, an impairment of the esthetics and sufficient adhesion of further reconstructions are crucial. Therefore, the aim of the article is to demonstrate the application of the FIT method as an efficient and straightforward approach for detecting and removing composite resin materials.
The teeth used in this study were part of a project approved by the local Ethics Committee (EKNZ UBE-15/111). The participants provided written informed consent, and all data were de-identified to protect patient confidentiality.
1. Detection of tooth colored composite resin material using FIT
2. Removal of composite resin-bonded trauma splints using FIT
Usage of the FIT method makes most composite resin materials appear brighter than sound tooth structure (Figure 2 and Figure 5). Therefore, FIT is applicable not only in the detection of composite resin material, but it also facilitates the removal of composite resin materials in general, and explicitly in posterior teeth, during orthodontic bracket debonding and in trauma splint removal1,2,24,25,26,27,28,29,30,31,32.
Figure 6 shows a tooth model after trauma splint removal under conventional illumination (teeth 13, 12, 11) and with the aid of FIT (teeth 21, 22, 23). Figure 6C shows the quantification of composite remnants and tooth substance loss in the software (unchanged areas: green, substance loss: blue and violet, excess material: yellow and red). The discrepancy of the pre- and postoperative scan measured by the Distance tool revealed composite remnants and substance loss of ± 0.1 mm in teeth 13, 12, and 11. Teeth 21, 22, and 23 showed nearly no changes in the surface (± 0.01 mm) after trauma splint removal. Moreover, the composite remnants are made visible by the FIT method (Figure 6B), whereas they remain undetected under conventional light illumination (Figure 6A).
Figure 1: Fluorescence-inducing light source. Please click here to view a larger version of this figure.
Figure 2: Tooth model with several composite resin restorations. (A) Conventional illumination, (B) FIT. Abbreviation: FIT = Fluorescence-aided Identification Technique. Please click here to view a larger version of this figure.
Figure 3: Preoperative scan and visualization of the volumetric changes after trauma splint removal. (A) Preoperative surface scan. (B) Visualization of the volumetric changes from pre- to postoperative scans in color (unchanged areas: green, substance loss: blue and violet, excess material: yellow and red). The color bar on the left enables the quantification of tooth substance loss and composite resin remnants. Please click here to view a larger version of this figure.
Figure 4: Suitable devices for the removal of composite resin during trauma splint removal. Left to right: diamond bur, bonding resin remover, mandrel, contouring and polishing discs, brush polishing system. Please click here to view a larger version of this figure.
Figure 5: Tooth model with trauma splint fixed with composite resin. (A) Conventional illumination, (B) FIT. Abbreviation: FIT = Fluorescence-aided Identification Technique. Please click here to view a larger version of this figure.
Figure 6: Tooth model after trauma splint removal under conventional illumination (teeth 13, 12, 11) and with the aid of FIT (teeth 21, 22, 23). (A) Under conventional light illumination, (B) illuminated by FIT (marked: composite remnants), (C) volumetric assessment (marked: composite remnants and substance loss). Abbreviation: FIT = Fluorescence-aided Identification Technique. Please click here to view a larger version of this figure.
The conventional illumination (for example by a dental unit lamp) is an unsatisfactory diagnostic tool for the identification of composite resin restorations. For superior diagnostics with conventional illumination, a magnification aid, drying, or even effortful cleaning of the teeth is necessary. Even under ideal circumstances, conventional illumination seems to be insufficient. A study showed that conventional illumination may lead to misdetection of composite resin restorations and sound tooth substance33. The FIT method seems to be superior in many ways. FIT is a diagnostic tool with a high accuracy, reproducibility, and repeatability1,2. Even obstructive factors such as saliva or biofilm do not influence the result of FIT1.
FIT also shows excellent inter- and intraoperator agreement1. Studies have shown FIT to provide satisfying results when used by dentists with different levels of experience1,33. Even dental students showed comparable results with experienced dentists using FIT1,33. However, the visual acuity which shows individual variation is influenced by many factors. In people above the age of 40 years, a physiological loosening of accommodation (presbyopia) occurs34. In studies, younger examiners under 40 years showed a higher sensitivity in detecting a composite resin restoration than a group older than 40 years33.
Any fluorescence-inducing light source is applicable for the FIT method33. Expensive and tedious systems can be avoided, and straightforward and low-cost systems, such as head-lamps, hand-lamps, or a modified micromotor can be favored. Given the availability of a suitable system for the FIT method, FIT is a diagnostic tool with a wide range of applications. FIT can be used for diagnostic purposes and as an additional tool for the removal of composite resin materials in reconstructive dentistry, dental traumatology (trauma splint removal), and orthodontics (bracket debonding)24,25,26,27,28,29,30,31,32. FIT is also advantageous in dental forensics, as several studies have found that more restoration sites can be detected using FIT35,36,37,38,39.
The evaluation of composite remnants and sound tooth substance loss after trauma splint removal using software after overlapping pre- and postoperative scans illustrates the accuracy of the FIT method. Intraoral scanners are suitable for this purpose since they are accurate and reliable28. Minor volumetric changes can be detected with a high level of precision28. Many of the available composite resin materials show fluorescence properties. However, fluorescence luminosity varies significantly according to the manufacturer and the shade of contemporary composite resin materials39.
Notably, some materials fluoresce less or even not enough for the application of the FIT method3,36,37,39. Moreover, the fluorescence signal of the composite resin materials decreases with time6,7,8,9. It might be harder to identify older composite resin restorations with the FIT method. These factors are the main drawback of the FIT method and must be taken into account when applying FIT. In conclusion, FIT is a reliable, fast, and noninvasive approach for the detection of composite resins.
The authors have nothing to disclose.
This study was supported by a research grant from the Swiss Dental Association (SSO Research Grant 292-16).
Bonding Resin Remover, H22ALGK 016 | Komet Dental, Lemgo, Germany | Any other material/equpiment with the same function/purpose might be used. | |
Cerec Omicam, Connect SW 5.1.3 | Dentsply Sirona, York, PA, USA | Any other material/equpiment with the same function/purpose might be used. | |
Diamant bur | Intensiv SA, Montagnola, Switzerland | Any other material/equpiment with the same function/purpose might be used. | |
Mandrell | 3M, Saint Paul, MN, USA | Any other material/equpiment with the same function/purpose might be used. | |
MASTERmatic | KaVo Dental GmbH, Biberach, Germany | Any other material/equpiment with the same function/purpose might be used. | |
Occlubrush | Kerr, Orange, CA, USA | brush polishing system | |
OraCheck Software, Version 5.0.0 | Cyfex AG, Zurich, Switzerland | Any other material/equpiment with the same function/purpose might be used. | |
SIROInspect | Dentsply Sirona, York, PA, USA | Any other material/equpiment with the same function/purpose might be used. | |
Sof-Lex | 3M, Saint Paul, MN, USA | Contouring/polishing discs; any other material/equpiment with the same function/purpose might be used. |