Fluorescence-aided Composite Removal in Directly Restored Permanent Posterior Teeth

Fluorescence intensity of composite resin for direct veneer removal using a fluorescence-aided identification technique

OBJECTIVES

This laboratory study evaluated the influence of the fluorescence intensity of composite resins on additional tooth wear and the presence of restorative material in different dental thirds during the retreatment of direct veneers.

MATERIALS AND METHODS

The crown dimensions of 60 bovine incisors were reduced to 10 × 8 mm. The teeth were classified according to the fluorescence intensity of the composites: low (LOW) (TPH Spectra), medium (MED) (Opallis), and high (HIGH) (Essentia) groups. The teeth were divided according to the removal methods: conventional (CON) and fluorescence-aided identification technique (FIT). The specimens were scanned (T0), received veneer preparation, and scanned again (T1). After restorations, the composites were removed and the teeth were scanned (T2). Measurement assessments between T1 and T2 were performed to determine additional wear, presence of residual areas, and the average between additional wear and the presence of residual areas. Kruskal Wallis, Mann-Whitney, Friedman, 2-way ANOVA, and post-Tukey tests were performed (α < 0.05).

RESULTS

The comparison of composite resins indicated a smaller area of additional wear and greater residue presence in the HIGH group than the LOW group for both techniques in the cervical third. Regarding removal methods, the FIT produced greater additional wear than the CON method for the LOW and MED groups in the middle and cervical thirds. The incisal third exhibited greater additional wear than the other thirds.

CONCLUSIONS

Composite resins with high fluorescence intensity removed using FIT had less tooth wear. The incisal third was the most affected area for direct veneer removal procedures.

CLINICAL SIGNIFICANCE

A FIT has been proposed for composite resin removal; however, the different fluorescence intensities of composite resins can influence tooth wear caused during this procedure.

In vitro evaluation of an easy-to-remove orthodontic adhesive with photochromic property

OBJECTIVES

To develop a photochromic bracket adhesive (PCA) with modification using photochromic material and evaluate the biocompatibility, bond strength, photochromic property, and adhesive removal efficiency.

MATERIALS AND METHODS

The resin-modified glass ionomer powder was mixed with the photochromic material and then blended with the liquid agent to form PCA. Biocompatibility was evaluated by CCK-8 kit, and shear bond strength (SBS) was measured. Stereoscopic microscopy and quantitative color analysis were used to assess the photochromic property. Bracket bonding and debonding procedures were performed on a head simulator with the assistance of an ultraviolet radiator. The effectiveness of adhesive removal during bonding and debonding procedures was assessed using a stereomicroscope. Removal time was recorded, and the enamel damage index after debonding was analyzed.

RESULTS

CCK-8 assay and SBS test indicated that 5wt.% mixing ratios of the photochromic material did not compromise the biocompatibility and SBS of the adhesive (PCA5). PCA5 showed photochromic properties and could help the operator remove adhesive more thoroughly without increasing enamel damage.

CONCLUSIONS

Photochromic adhesive (PCA5) can be good for orthodontic adhesive removal and therefore has good clinical translation potential.

Evaluation of five methods to identify composite restorations in human teeth on a forensic purpose-an ex vivo comparative study

The use of tooth-colored composite resin materials in dentistry is increasing. As composite restorations appear similar to the natural tooth structure, their detection is becoming more challenging. The aim of this study was to compare five diagnostic methods for detection of dental restorations and to create reliable postmortem dental records for forensic purposes. A conventional examination method without a direct light source (CONV), with a dental loupe light (DL), Galilean loupes with a direct light source (GDL), a fluorescence-inducing device (FIT), and intraoral radiographs (RX) were compared. Dentists specializing in conservative dentistry or oral surgery and dentistry students participated. Regarding sensitivity, specificity, positive predictive value, and negative predictive value, FIT and RX showed significantly higher results than CONV, DL, and GDL. RX and FIT showed comparable results in identifying composite restorations but depending on their location. The combination of both methods may lead to even better results. In conclusion fluorescence-inducing devices show good results in identifying composite restorations and therefore should be considered as a standard tool in forensic examinations. Another advantage is their small size, low cost, and mobility. Good illumination and magnification devices are recommended to enhance performance during conventional examinations. Involving dentists specialized in conservative dentistry could contribute to dental identification.

Fluorescence-aided identification technique using a low-cost violet flashlight and rotatory instruments for dental trauma splint removal

BACKGROUND/AIM

Removing resin composites used for bonding dental trauma splints may result in irreversible damage to the enamel. This in vitro study evaluated the influence of additional violet illumination and different bur types on damage caused to tooth enamel.

MATERIALS AND METHODS

Fifteen maxillary models with four bovine incisor teeth were prepared. All models were scanned using a laboratory scanning system (s600 ARTI; Zirkonzahn). Six experimental groups (n = 10) were generated by two study factors: lighting type (three levels), (1) low-cost (5-7 US$) violet LED flashlight (LUATEK, LT 408); (2) VALO Cordless light curing unit (Ultradent) with black lens; or (3) without additional illumination; and rotatory instrument (two levels), (1) diamond bur or (2) multifluted tungsten-carbide bur. New scanning was performed after splint removal, and the generated files were superimposed on the initial scans using Cumulus software. The light emitted by both violet light sources was characterized by using integrating sphere and beam profile. A qualitative and quantitative analysis of enamel damage and two-way ANOVA followed by Tukey's post hoc was used at an α = 0.05.

RESULTS

The use of low-cost violet flashlight that emitted the violet peak light at 385 nm and VALO Cordless with black lens at 396 nm resulted in significantly lower damage to the enamel surface than those in the groups without additional violet light (p < .001). An interaction between rotatory instruments and lighting was found. When no additional violet lighting was used, the diamond bur presented higher mean and maximum depth values.

CONCLUSIONS

Fluorescence lighting facilitated the removal of remnant resin composite dental trauma splints, leading to less invasive treatment. The diamond bur resulted in higher enamel damage than that affected by the multifluted bur when no violet lighting was used. A low-cost violet flashlight is a useful fluorescence-aided identification technique for removing resin composite dental trauma splints.

Quality of CAD-CAM inlays placed on aged resin-based composite restorations used as deep margin elevation: a laboratory study

OBJECTIVES

To assess the impact of the age of resin-based composite (RBC) restorations used for deep margin elevation (DME) on the marginal quality and fracture resistance of inlays.

MATERIALS AND METHODS

Permanent human molars with direct RBC restorations, involving the mesial, occlusal, and distal surface (MOD), were allocated to four groups (each n = 12). Half of the teeth underwent thermomechanical loading including 240,000 occlusal load cycles and 534 thermal cycles (TML, 5 °C/55 °C; 49 N, 1.7 Hz). With RBC left in one proximal box as DME, all teeth received MOD inlays, made from lithium disilicate (LDS) or a polymer-infiltrated ceramic network material (PICN). The restored teeth underwent TML including 1.2 million occlusal cyclic loadings and 2673 thermal cycles. The marginal quality was assessed at baseline and after both runs of TML. Load-to-fracture tests were performed. The statistical analysis comprised multiple linear regressions (α = 0.05).

RESULTS

Simulated aging of RBC restorations had no significant effect on the marginal quality at the interface between the RBC and the tooth and the RBC and the inlay (p ≥ 0.247). Across time points, higher percentages of non-continuous margin were observed between the inlay and the tooth than between the tooth and the RBC (p ≤ 0.039). The age of the DME did not significantly affect the fracture resistance (p ≥ 0.052).

CONCLUSIONS

Artificial aging of RBC restorations used for DME had no detrimental effect on the marginal quality and fracture resistance of LDS and PICN inlays.

CLINICAL RELEVANCE

This laboratory study suggests that-in select cases-intact, direct RBC restorations not placed immediately before the delivery of an indirect restoration may be used for DME.

Efficacy of Bracket Adhesive Remnant Removal by a Fluorescence-Aided Identification Technique with a UV Light Handpiece: In Vitro Study

Objective

This study aims to analyze the fluorescence-aided identification technique efficacy on adhesive remnant removal from the enamel surface after orthodontic bracket debonding.

Materials and Methods

Forty-five extracted human upper central incisors were divided into 3 groups (n = 15) according to the kind of adhesive for bracket bonding and the use or absence of near UV light for remnant removal: BF/UV- fluorescent adhesive/UV light, BF/0-fluorescent adhesive/no UV light, and TB/0-nonfluorescent adhesive/no UV light. For all teeth, 100% of the adhesive used remained on the enamel surface after debonding. Fifteen dentists performed adhesive removal on the enamel surface using a carbide bur. The specimens were analyzed by a stereomicroscope, and the adhesive remnant percentage from each specimen was calculated. The time used by each dentist to perform the removal was recorded. The data were analyzed by one-way ANOVA and Tukey's test.

Results

Significant differences were observed among groups for adhesive remnant (p=0.0008) and for time (p=0.0001). The means of adhesive remnant were BF/UV (5.84), BF/0 (34.37), and TB/0 (37.02). The mean times necessary to remove adhesive were BF/UV (1 min 40 s), BF/0 (3 min 03 s), and TB/0 (2 min 46 s). For the BF/UV group, significantly lower values of adhesive remnants and time for debonding were found (p < 0.05).

Conclusion

The fluorescence-aided identification technique significantly reduced the amount of adhesive remnant, and the time necessary to perform this clinical procedure.

Fluorescence-aided removal of orthodontic composites: an in vivo comparative study

Background

To compare the fluorescent properties of 6 different orthodontic adhesives and provide useful information for clinicians in the adhesion choice, in order to remove it easily at the end of orthodontic treatment by using the Fluorescence-aided Identification Technique (FIT).

Methods

Six orthodontic adhesives were included: Ortho Connect, Gradia LoFlo A3.5, Greengloo, Transbond XT, KommonBase Pink, and KommonBase Clear. The same thermoformed template with 1 mm shell thickness on the six anterior teeth was used for adhesive positioning; furthermore, an ultraviolet light-emitting diode flashlight was used for the FIT. The brightness of adhesive area and tooth area (L* color coordinate) were measured on the photographs by using the “color picker” tool of Photoshop software.

Results

GC Ortho Connect, Gradia Direct LoFlo and KommonBase Clear showed the highest differences of brightness (15.5, 16.3 and 13.5, respectively), while Greengloo, Transbond XT and KommonBase Pink registered similar values between resin area and tooth area with FIT (− 0.5, − 0.8 and − 1.0, respectively). The high viscosity adhesive resins, as Greengloo and Transbond XT, showed a similar performance in terms of fluorescence to the KommonBase Pink, the lowest viscous resin adhesive considered.

Conclusions

The most used orthodontic adhesives showed different fluorescence properties. Some resins were brighter with the FIT, facilitating identification and subsequent removal. Other orthodontic adhesives presented no difference between adhesive and tooth. The viscosity of orthodontic adhesives did not influence the brightness emitted with FIT.

Fluorescence-Aided Identification Technique (FIT) Improves Tooth Surface Clean-Up after Debonding of Buccal and Lingual Orthodontic Appliances

The aim of this study was to evaluate the use of fluorescence inducing light to aid the clean-up of tooth surfaces after bracket removal when using buccal or lingual orthodontic appliances. Two full sets of dental arches using extracted human teeth were assembled, with 14 teeth per arch. All teeth were bonded on their buccal and lingual surfaces. After debonding, a single blinded operator performed the tooth surface clean-up, as commonly performed in clinical practice; without the use of fluorescent light (non-FIT) and with two methods using fluorescent light to identify composite remnants on the tooth surfaces (FIT; OPAL and BRACE). Tooth surfaces were scanned before bonding and after clean-up, and the two scans were superimposed using the best-fit method. The results showed that the debonding method, type of tooth and type of tooth surface had a significant effect on the presence of composite remnants, enamel defects, and on debonding time. Contrary to the non-FIT method, there were no composite remnants after clean-up with the use of fluorescence inducing light. Clean-up time was significantly reduced on the buccal surfaces when using the FIT methods. On the lingual surfaces, the FIT methods resulted in larger enamel defects.

Effect of handpiece light and material used in pulp chamber on dentin removal during root canal retreatment

This study evaluated the effect of the use of glass ionomer cement (GIC) and flowable bulk-fill resin composite (BFRC) for filling pulp chambers and the type of high-speed handpiece light used on dentin removal during access preparation for endodontic retreatment in molar teeth. Twenty maxillary molars were treated endodontically. BFRC (Opus Bulk Fill Flow APS, FGM) was used to fill the pulp chamber and replace coronal dentin (n = 10). In the remaining teeth, the pulp chamber was filled with GIC (Maxion R, FGM). Conventional resin composite (Opallis, FGM) was used to restore the enamel layer in all teeth. The samples in each group were divided into two subgroups, and the root canals were reaccessed using a handpiece with white or ultraviolet light. The teeth were scanned using micro-CT before and after root canal reaccess. The dentin volume removed was calculated and analyzed using 2-way analysis of variance and Tukey's test (α = 0.05). The crown and pulp chamber locations with dentin removal are described using frequency distribution. During the access, fewer pulp chamber walls were affected and a lower volume of dentin was removed from the pulpal floor in the group restored with GIC than in the group restored with BFRC. No effect was observed on the coronal dentin walls with respect to the filling protocols and type of light used. For dentin removal from the pulp chamber, handpieces with white light performed better than those with ultraviolet light, irrespective of the filling protocol used. The use of GIC to fill the pulp chamber and use of white handpiece light reduced dentin removal from the pulpal floor and resulted in fewer affected dentin walls.

Use of auxiliary devices during retreatment of direct resin composite veneers

The removal of direct composite veneers, when the retreatment is necessary, represents a challenge to the clinician, since the healthy dental structure must be preserved. Thus, the aim of this study was to compare the accuracy provided by different auxiliary devices during retreatment of direct composite veneers. Seventy-five bovine teeth were prepared for direct composite veneers, scanned (T1), and restored. Specimens were divided into 5 groups for retreatment: conventional high-speed handpiece without auxiliary device (WD); high-speed handpiece with a white LED (WL); high-speed handpiece with an UV light (UL); electric motor and multiplier 1/5 handpiece (EM); and conventional high-speed handpiece using magnifying loupe (ML). After retreatments, other scanning was performed (T2). Changes on dental wear or composite residues areas, as well as, the average between wear and presence of residues were measured. Data were submitted to Kruskal-Wallis and Dunn’s post-test (p≤ 0.05). There were greater areas of wear for ML, being statistically superior to WD and EM groups. The ML presented smaller residues areas, being statistically lower than the WD and EM groups. Regarding the average between wear and the presence of resin residues, additional wear occurred after re-preparation, regardless of the group. Magnifying loupe promoted greater areas of wear and smaller areas of resin residues than conventional high-speed handpiece and electric motor. Both techniques using light accessories did not differ from other ones.

Accuracy of the fluorescence-aided identification technique (FIT) for detecting tooth-colored restorations utilizing different fluorescence-inducing devices: an ex vivo comparative study

OBJECTIVES

The aim of the present study was to compare the accuracy of the conventional illumination method (CONV) and the fluorescence-aided identification technique (FIT) for distinguishing between composite restorations and intact teeth using different fluorescence-inducing devices commonly used for FIT.

MATERIALS AND METHODS

Six groups of six dentists equipped with one of six different FIT systems each independently attempted to identify composite restorations and intact teeth on a full-mouth model with 22 composite restorations using CONV and, 1 h later, FIT. The entire procedure was repeated 1 week later. Sensitivity, specificity, and positive (PPV) and negative (NPV) predictive values, including 95% confidence intervals (CI), were calculated for CONV and FIT overall and for each device. The influence of examiner age, method, and device on each parameter was assessed by multivariate analysis of variance.

RESULTS

The sensitivity (84%, CI 81-86%), specificity (94%, CI 93-96%), PPV (92%, CI 90-94%), and NPV (90%, CI 88-91%) of FIT was significantly higher than that of CONV (47%, CI 44-50%; 82%, CI 79-84%; 66%, CI 62-69%, and 69%, CI 68-71%, respectively; p<0.001). The differences between CONV and FIT were significant for all parameters and FIT systems except VistaCam, which achieved no significant difference in specificity. Examiners younger than 40 years attained significantly higher sensitivity and negative predictive values than older examiners.

CONCLUSIONS

FIT is more reliable for detecting composite restorations than the conventional illumination method.

CLINICAL RELEVANCE

FIT can be considered an additional or alternative tool for improving the detection of composite restorations.

Restorative CAD/CAM materials in dentistry: analysis of their fluorescence properties and the applicability of the fluorescence-aided identification technique (FIT)

OBJECTIVES

This study investigated the fluorescence properties of the most commonly used fluorescent CAD/CAM materials for monolithic dental restorations and their suitability to perform the fluorescence-aided identification technique (FIT).

MATERIALS AND METHODS

A total of 175 different color shades (n = 1) from 13 CAD/CAM material brands were analyzed with a monochromator-based microplate reader. Additionally, dentin, enamel, and combined dentin-enamel specimens (respectively, n = 11) were analyzed for comparison purposes. The maximum fluorescence intensity, the corresponding excitation and emission wavelength, and the total fluorescence for the wavelength spectrum λ_ex = 395 nm - 415 nm used for FIT were determined.

RESULTS

All assessed CAD/CAM ceramics showed virtually no total fluorescence for the wavelength spectrum λ_ex = 395 nm - 415 nm used for FIT. CERASMART^TM, KZR-CAD HD 2, and LuxaCam Composite displayed total fluorescence values similar to that of the tooth hard substances. All other resin-based CAD/CAM materials showed a significantly higher total fluorescence than the tooth hard substances.

CONCLUSIONS

Apart from the mentioned exceptions, all CAD/CAM materials assessed could be suitable for the FIT, either because they are more fluorescent than hard tooth substances or because they do not fluoresce at all at the respective wavelength of λ_ex = 395 nm - 415 nm.

CLINICAL RELEVANCE

This study provides insight into the not yet well-known fluorescent properties of dental CAD/CAM materials. This knowledge is not only necessary to reproduce the fluorescence properties of natural teeth but also for the applicability of diagnostic fluorescence inducing techniques.