Detection and Removal of Tooth-Colored Composite Resin Using the Fluorescence-Aided Identification Technique

Summary

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.

Abstract

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.

Introduction

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 lamp^1,2. 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 resins^4,5. 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 resins^4,5. FIT is applicable on many composite resin materials as they show these fluorescence properties³. However, fluorescence decreases with the ageing of the composite resin materials^6,7,8,9.

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 perfectly^10,11. 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 reasons^14,15. 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 margins^{1,16,17,18,19,20,21,22}. On the contrary, an overpreparation due to misdiagnosis of composite resin versus tooth structure may result in unnecessary substance loss^1,2.

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.

Protocol

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

1. Darken the room (natural and artificial light).
2. Wear clear or yellow-tinted safety glasses with UV protection.
3. Use a fluorescence-inducing light source to illuminate the tooth substance and tooth-colored composite resin restoration (Figure 1).
   NOTE: The composite resin material will appear brighter than the tooth substance (Figure 2). Any device with a wavelength of 398 ± 5 nm might be used as a fluorescence-inducing light source. Headlamp systems appear to be particularly suitable since the light spot illuminates the entire oral cavity and enables simultaneous tactile examination. Obstructive factors such as saliva and plaque do not interfere with the FIT method; therefore, previous cleaning and repeated drying of the teeth is not necessary.

2. Removal of composite resin-bonded trauma splints using FIT

1. Preoperative scan with an intraoral scanning device and appropriate software for experimental evaluation purposes
   1. Start the intraoral scanning device and open the software (see the Table of Materials).
   2. Press Add New Patient to register your patient, fill in the gaps Last Name, First Name, Date of Birth, and Patient ID, and press Add Case.
   3. Choose Jaw Scan and Impressions under the section Indications. Then, press Next.
   4. Darken the room (natural and artificial light) and dry the field of operation to ease the scanning procedure.
   5. Start the intraoral scanner and perform a digital surface scan of the field of operation (Figure 3A).
2. Visualization of the composite resin material
   1. Repeat steps 1.1-1.3.
   2. Remove the composite resin material using the common methods (e.g., a high-speed contra-angle handpiece with diamond burs and polishing devices) (Figure 4).
      NOTE: Remove the composite resin remnants close to the enamel with a carbide bur designed for debonding.
3. Postoperative scan for experimental volumetric assessment
   1. Repeat steps 2.1.1-2.1.5.
       
       
4. Experimental volumetric assessment
   1. Press Export to export the pre- and postoperative scans as surface tessellation language (STL) in highest resolution.
   2. Open suitable software and press recombine.
   3. Upload the pre- and postoperative scans to the software by pressing Import.
   4. Press Arrangement to superimpose the pre- and postoperative scans by the best fit method.
   5. Press Analysis to visualize the volumetric changes from pre- to postoperative scans. Select the tooth sites where volumetric changes presumably occurred by choosing Region under the section Tools. Analyze volumetric changes by using the linear and volumetric measurement software tools, Distances tool and Volume Analysis tool, respectively.
      1. Press Distances under the section Tools for linear quantification of tooth substance loss and composite resin remnants in color (e.g., unchanged areas: green, substance loss: blue and violet, excess material: yellow and red, Figure 3B). Use the color bar on the left to quantify linear volumetric changes. Additionally, locate the cursor on the relevant tooth sites; look for the exact cursor distance in the box on the left.
      2. Press Volume Analysis under the section Tools for volumetric quantification of tooth substance loss and composite resin remnants . Look for the volumetric change in the box on the left.

Results

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 removal^1,2,

Discussion

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 substance

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
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.