Enamel loss and adhesive remnants following bracket removal and various clean-up procedures in vitro

Optimizing Ultraviolet Illumination for Detecting Fluorescent Orthodontic Adhesive Residues during Debonding Procedures

BACKGROUND

Fluorescence-aided identification technique (FIT) studies for orthodontic resins are relatively new, using an arbitrary selection of resins, lights, and work parameters. In order to provide FIT guidelines for optimal visualization, the objectives of this study were to describe the electromagnetic characteristics of fluorescent orthodontic resins, determine appropriate light specification, and describe light and work parameter effects on resin fluorescence.

METHODS

This in vitro study assessed five fluorescent orthodontic resins and a non-fluorescent control resin using spectrophotometry, a scaled image analysis of 25 μm thick resins to compare intensities, and a visual assessment. Light sources varied by flashlight lens (narrow [N], average [X], and magnified [Z]) and UV intensity (X and X High). Work parameters included distance (20-300 mm) and angulation (15-70°). Visual scores were assigned to determine discernibility.

RESULTS

The average excitation maxima was 384 nm. Fluorescence increased with more direct UV light exposure. The highest intensity was recorded with Light X High at 50 mm and 70°. Visual assessment followed image analysis trends, and fluorescence was clinically discernable for all 25 μm thick samples.

CONCLUSIONS

Excitation wavelength range of 395-405 nm is appropriate for FIT illumination. All resins were anisotropic and showed greater fluorescence with greater angle, higher UV intensity, and closer proximity.

Structural and Color Alterations of Teeth following Orthodontic Debonding: A Systematic Review

AIM

The objective of this study was to explore the effects of fixed orthodontic appliances on enamel structure by assessing microfractures, surface roughness, and alterations in color.

METHODS

This review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. A systematic search of online databases was conducted using the keywords 'enamel' AND 'orthodontic debonding'. Eligibility criteria included both in vivo and ex vivo clinical trials conducted on human teeth.

RESULTS AND DISCUSSION

A total of 14 relevant papers were analyzed. Various instruments and techniques were utilized across different studies to assess surface roughness, color change, and surface fractures.

CONCLUSIONS

The findings of this study suggest that ceramic brackets may lead to an increase in enamel fractures, particularly during bracket removal. The surface roughness of enamel exhibits variability depending on the adhesive substance and polishing methods used post-removal. Fixed orthodontic appliances could induce changes in enamel color, which may be alleviated by the use of nano-hydroxyapatite or specific polishing techniques. Further research is necessary to identify effective strategies for managing these color changes and improving the overall outcomes of fixed orthodontic treatment.

In Vitro Study on the Influence of the Buccal Surface Convexity of the Tooth upon Enamel Loss after Bracket Removal

Polishing after the removal of brackets is the final step in orthodontic treatment. It is simple to perform, though some studies have reported that polishing causes damage to the enamel surface. An in vitro study was made of the influence of the buccal surface convexity of the tooth upon possible enamel loss when the remaining resin and adhesive are removed after bracket decementing using two different polishing modes: a tungsten carbide bur at low and high speeds. The convexity of the buccal surface was quantified in 30 incisors and 30 premolars. A stereoscopic microscope was used to obtain photographs of the profile of the crown, and Image J software was used to calculate convexity by dividing the length of a line from the cementoenamel junction to the incisal margin by another line from the mentioned junction to the maximum convexity of the buccal surface. Brackets were cemented on all the teeth and were decemented 24 h later. In both groups, the residual composite was removed with a tungsten carbide bur at a low speed in one-half of the teeth and at a high speed in the other half. The buccal surface of each tooth was then photographed again, and the convexity was calculated and compared against the baseline value. The difference between the two values were taken to represent the enamel loss. The convexity of the premolars was significantly greater than that of the incisors, but this did not result in greater enamel loss when the same polishing mode was used. However, the tungsten carbide bur at a high speed proved more aggressive, causing significantly greater enamel loss than when used at a low speed.

Evaluation of enamel surface integrity after orthodontic bracket debonding: comparison of three different system

OBJECTIVE

This study aimed to evaluate enamel surface integrity and time consumed during residual cement removal after bracket debonding using different adhesive removal burs with and without a dental loupe.

MATERIAL AND METHODS

Sixty human-extracted premolars were collected, cleaned, mounted, and prepared for orthodontic bracket bonding. Teeth were randomly divided into three main groups (n = 20) based on the adhesive removal method: tungsten carbide system (TC), sof-lex discs system (SD), and diamond system (DB) groups. Then, each group was subdivided into two subgroups (naked eye and magnifying loupe subgroups). The brackets were bonded and then debonded after 24 h, and the Adhesive Remnant Index (ARI) was assessed. The adhesive remnants were removed by different systems, and the final polishing was performed by Silicone OneGloss. The enamel surface roughness was evaluated before bracketing (T0), after residual cement removal (T1), and finally after polishing (T2) using surface Mitutoyo SJ-210 profilometry and Scanning Electron Microscopy (SEM) to determine the Enamel Damage Index (EDI) score. The time consumed for adhesive removal was recorded in seconds.

RESULTS

The Kruskal Wallis test showed a statistically significant difference in roughness values at T1 compared to T2 between subgroups (p < 0.001). When comparing EDI at T1 and T2, the Kruskal-Wallis H-test showed statistically significant differences in all subgroups. The pairwise comparisons revealed that EDI scores showed a statistically significant difference at T1 and T2 between DB vs. TC and SD (p = 0.015) but not between TC vs. SD (p = 1.000), indicating the highest roughness value observed in the DB group. The time for cement removal was significantly shorter in the magnifying loupe group than in the naked eye group and was shortest with the TC group, whereas the time was the longest with the DB group (p < 0.05).

CONCLUSION

All three systems were clinically satisfactory for residual orthodontic adhesive removal. However, TC system produced the lowest enamel roughness, while the DB system created the greatest. The polishing step created smoother surfaces regardless of the systems used for resin removal.

Quantitative light-induced fluorescence enables effective detection of orthodontic adhesive residues in diverse environments

BACKGROUND

Adhesive remnants post-orthodontic treatment might have deleterious effects on oral health, including enamel demineralization, plaque accumulation, and elevated risk of caries development. The aim of this study was to identify and characterize adhesive residues in an ex vivo environment rich in salivary microbiota using quantitative light-induced fluorescence (QLF) technology.

METHODS

Disc-shaped adhesive samples with thickness ranging from 800 to 100 µm were prepared using GC Ortho, GOTO, T Orthobond, and Transbond XT and subsequently evaluated utilizing a QLF system. Bovine teeth containing GC Ortho and GOTO adhesives and isolated human premolar teeth bonded with brackets were subjected to a 10-day incubation in an artificial saliva environment. Daily imaging was conducted using QLF during incubation. Data with ΔR > 30% and simple hygiene score (SHS) were obtained with a software for further analysis.

RESULTS

Fluorescence intensity exhibited significant differences among the four orthodontic adhesives (p < 0.05). Results of incubation in artificial saliva revealed that red fluorescence surrounding the adhesive on the tooth surface was distinctly observable from day five onwards, with ΔR > 30% and SHS levels higher than those of the control group without adhesive (p < 0.05). Observation of fluorescence images of isolated human premolar teeth with bonded brackets indicated that red fluorescence was primarily present around the brackets.

CONCLUSIONS

Application of QLF is efficacious in identifying and demarcating adhesive residues within an environment rich in salivary microbiota.

Teeth Microcracks Research: Towards Multi-Modal Imaging

This perspective is an overview of the recent advances in teeth microcrack (MC) research, where there is a clear tendency towards a shift from two-dimensional (2D) to three-dimensional (3D) examination techniques, enhanced with artificial intelligence models for data processing and image acquisition. X-ray micro-computed tomography combined with machine learning allows 3D characterization of all spatially resolved cracks, despite the locations within the tooth in which they begin and extend, and the arrangement of MCs and their structural properties. With photoluminescence and micro-/nano-Raman spectroscopy, optical properties and chemical and elemental composition of the material can be evaluated, thus helping to assess the structural integrity of the tooth at the MC site. Approaching tooth samples having cracks from different perspectives and using complementary laboratory techniques, there is a natural progression from 3D to multi-modal imaging, where the volumetric (passive: dimensions) information of the tooth sample can be supplemented by dynamic (active: composition, interaction) image data. Revelation of tooth cracks clearly shows the need to re-assess the role of these MCs and their effect on the structural integrity and longevity of the tooth. This provides insight into the nature of cracks in natural hard materials and contributes to a better understanding of how bio-inspired structures could be designed to foresee crack propagation in biosolids.

Comparison of Enamel Surface Integrity after De-Bracketing as Affected by Seven Different Orthodontic Residual Cement Removal Systems

This study used seven different adhesive removal systems to evaluate and compare enamel surface integrity, heat generation, and time consumed during residual cement removal after de-bracketing. The sample size was 140 human premolars. Teeth were cleaned, mounted, and prepared for orthodontic bracket bonding. Brackets were then debonded using bracket-removing pliers. Teeth were randomly assigned to seven groups based on the residual cement removal system: Group 1: Stainbuster bur, Group 2: Renew diamond bur #129, Group 3: Renew carbide bur, Group 4: OneGloss Complete system, Group 5: Sof-Lex system, Group 6: Enhance Finishing and PoGo Polishing complete kit, and Group 7: Renew friction grip points. The enamel surface was evaluated for roughness before bracketing and after residual cement removal using surface profilometry. The time taken for cement removal was recorded using a digital timer, and heat generation was measured using a laser thermometer before and after cement removal. One-way ANOVA compared the pre- and post-values for enamel surface roughness, temperature, and time consumed. When comparing the difference between the post- and pre-finishing roughness using one-way ANOVA, the Renew diamond bur produced the roughest enamel surface post-removal with a mean of 4.716 μm, while the Sof-Lex recorded the lowest at 0.760 μm. The highest mean temperature was recorded with the Stainbuster bur at 5.545 °C, and the lowest temperature was recorded with the Enhance bur at 2.260 °C. The time for cement removal was the shortest with the Enhance bur at 12.2 s, whereas the time was the longest with the Renew diamond bur at 30.4 s. In conclusion, all the residual cement removal systems used in this clinically simulated study were not able to restore the original enamel surface smoothness. However, the 3M Sof-Lex produced the lowest enamel roughness but with more time consumption and heat generation. When selecting the best residual cement removal system to be used, clinicians should weigh the merits and demerits of each system based on the clinical judgement of the operator.

Evaluation of enamel roughness after orthodontic debonding and clean-up procedures using zirconia, tungsten carbide, and white stone burs: an in vitro study

BACKGROUND

The main goal of orthodontic debonding is to restore the enamel surface as closely as possible to its pretreatment condition without iatrogenic damage. This study aimed to compare the effects of different adhesive removal burs; zirconia burs, tungsten carbide burs, and white stone burs on enamel surface roughness.

MATERIALS AND METHODS

Total sample of 72 extracted premolars was randomly divided into three equal groups (n = 24) depending on the method of adhesive removal: zirconia burs (ZB); tungsten carbide burs (TC); and white stones (WS). The metal brackets were bonded using Transbond XT orthodontic adhesive (3 M Unitek, Monrovia, CA, USA) and debonded after 24 h using a debonding plier, then the ARI was assessed. The adhesive remnants were removed using the different burs and Final polishing was performed using Sof-lex discs and spirals. Thirteen samples from each group were evaluated using a Mitutoyo SJ-210 profilometer to determine average surface roughness (Ra) and three samples from each group were examined under Scanning Electron Microscopy (SEM) to determine EDI score. The evaluations were performed at three time points; before bonding (T0), after adhesive removal (T1) and after polishing (T2) and the time consumed for adhesive removal by burs was recorded in seconds. The data were analyzed statistically by ANOVA, Tukey's test and Kruskal-Wallis H-test.

RESULTS

Kruskal-Wallis H-test showed no statistically significant difference of ARI in all studied groups (p = 0.845) and two-way mixed ANOVA revealed that all burs significantly increased surface roughness at T1 compared to T0 (p < 0.001) in all groups with the lowest Ra values were observed in the ZB group, followed by the TC group, and WS group. The fastest procedure was performed with WS, followed by ZB, then TC bur (p < 0.001). After polishing (T2), Ra values showed no significant difference in ZB group (P = 0.428) and TC group (P = 1.000) as compared to T0, while it was significant in WS group (p < 0.001).

CONCLUSION

zirconia bur was comparable to tungsten carbide bur and can be considered as alternative to white stone which caused severe enamel damage. The polishing step created smoother surface regardless of the bur used for resin removal.

Shear bond strength of adhesive precoated brackets: A comparative in vitro study

OBJECTIVE

This study compared the shear bond strength of orthodontic precoated brackets from different manufacturers.

METHODS

Sixty extracted human premolar teeth were divided into six groups (n=10). The groups were bonded with one of the following brackets: 3M™ Unitek Victory™ Series™ with APC, 3M™ Unitek Clarity™ Advanced Ceramic™ with APC, TP Nu-Edge® NX Cobalt-Chromium and TP In-Vu® ceramic Readi-Base® both with eXact® orthodontic adhesive, 3M™ Unitek Clarity Advanced Ceramic™ and 3M™ Unitek Victory™ Series™ both with Transbond™ XT Adhesive. Each group was tested for shear bond strength using a universal testing machine. Each sample was observed under a dissecting microscope and received an adhesive remnant index (ARI) score. Statistical analysis was performed using Tukey's Standardized Range (HSD) Test to make comparisons among all groups and a Wilcoxon rank-sum test to evaluate for pairwise comparisons between the groups. The P-values<0.05 were considered significant.

RESULTS

The ceramic control was not statistically different from the metal control, 3M™ Victory™ APC™, TP In-Vu® ceramic eXact® or TP Nu-EDGE® eXact® in terms of shear bond strength (7.69±1.41MPa, 7.72±1.25MPa, 8.70±1.93MPa, 4.90±1.76MPa, 5.33±0.78MPa, respectively). However, it was statistically different from 3M™ Ceramic APC™ (10.29±2.78MPa). In terms of modulus, there were no statistical differences. TP's Nu-edge® had the lowest average ARI score, but was not statistically different when compared to the other groups.

CONCLUSION

3M™ Unitek's Ceramic APC had a statistically higher SBS than the non-precoated brackets and TP Orthodontics' precoated brackets. However, all SBS were 4.9 MPA or above, which is deemed clinically acceptable in terms of laboratory forces. There was no statistical difference between manufacturing companies or precoated vs. non-precoated modulus and ARI scores.

Enamel Evaluation after Debonding of Fixed Retention and Polishing Treatment with Three Different Methods

Lack of standardization of the retention phase has led to many studies of stability of movements and characteristic of retainers, disregarding the enamel repercussions of fixed retention on this phase. This study aimed to analyze different methods of enamel polishing after detachment of orthodontic retainers. Forty-five healthy premolars were divided into three groups according to the polishing bur after debonding, and four specimens without intervention were used as control. A 0.038 × 0.015 inches gold chain was bonded between the premolars and then removed. The adhesive remnant was removed with three types of burs according to the study groups (Group 1: white stone at high speed; Group 2: high-speed handpiece with a 30-blade tungsten carbide bur; Group 3: low-speed handpiece and a 30-blade tungsten bur). After debonding and polishing, all samples were analyzed with a confocal microscopy on surface roughness parameters: Sa: Arithmetic mean of the height of the surface. Rq: Square mean of the height of the surface and Sz: Maximum surface height. Mechanical tests were carried out to determine the bonding stress of the retention adhered to the teeth using an electromechanical testing machine. The adhesion stress was 8.23 MPa (±0.87). The quality of the refinement of the enamel after debonding is essential in order to preserve its integrity. The use of the 30-blade tungsten carbide bur provides a smooth enamel surface after polishing.

Introducing and assessing the efficacy of a novel method to reduce enamel damage after orthodontic bracket removal using two herbal-based resin colouring agents: An in vitro study

PURPOSE

The differentiation of resin remnants from enamel is a critical factor to minimize enamel damage after bracket debonding. This study was conducted to produce, and ascertain the efficacy of two colouring agents in minimizing enamel loss, adhesive and bonding remnants, and surface roughness after debonding.

METHODS

Two dyes containing annatto (orange colour) and curcumin (yellow colour) were produced. Seventy-two maxillary premolars were divided into three groups. After bracket bonding and debonding, the adhesive remnant was removed with a fine diamond bur. In groups 1 and 2, the orange and yellow dyes were utilized during the removal process, respectively. In group 3 (control) adhesive was removed with no colouring agent. The buccolingual dimension of the teeth was measured at the occlusal, middle, and apical areas, before bonding and after clean-up. The adhesive remnant index (ARI) and bonding remnant index (BRI) scores were recorded and the surface roughness parameters were measured. Data were analysed by ANOVA, Tukey, and Fisher's exact tests (α=0.05).

RESULTS

Enamel loss was significantly lower in the groups cleaned by the use of colouring agents than that of the control group (P<0.05). No bonding agent was observed when the dyes were used, whereas 65% of teeth in the control group showed the remaining bonding material (P<0.001). There was no significant difference in ARI scores or surface roughness alterations among the study groups (P>0.05).

CONCLUSION

The two dyes produced in this study were effective in enhancing the visibility of residual resin materials and minimizing enamel loss during the clean-up process.

Revelation of microcracks as tooth structural element by X-ray tomography and machine learning

Although teeth microcracks (MCs) have long been considered more of an aesthetic problem, their exact role in the structure of a tooth and impact on its functionality is still unknown. The aim of this study was to reveal the possibilities of an X-ray micro-computed tomography ([Formula: see text]CT) in combination with convolutional neural network (CNN) assisted voxel classification and volume segmentation for three-dimensional (3D) qualitative analysis of tooth microstructure and verify this approach with four extracted human premolars. Samples were scanned using a [Formula: see text]CT instrument (Xradia 520 Versa; ZEISS) and segmented with CNN to identify enamel, dentin, and cracks. A new CNN image segmentation model was trained based on "Multiclass semantic segmentation using DeepLabV3+" example and was implemented with "TensorFlow". The technique which was used allowed 3D characterization of all MCs of a tooth, regardless of the volume of the tooth in which they begin and extend, and the evaluation of the arrangement of cracks and their structural features. The proposed method revealed an intricate star-shaped network of MCs covering most of the inner tooth, and the main crack planes in all samples were arranged radially in two almost perpendicular directions, suggesting that the cracks could be considered as a planar structure.

Comparison of Enamel Surface Roughness after Bracket Debonding and Adhesive Resin Removal Using Different Burs with and without the Aid of a Magnifying Loupe

AIM

This study aimed to evaluate the impact of using a magnifying dental loupe on enamel surface roughness during adhesive resin removal by different burs.

MATERIALS AND METHODS

Ninety-six extracted premolar teeth were randomly divided according to the bur used with or without the aid of a magnifying loupe into four equal groups (N = 24): group I: naked eye tungsten carbide burs (NTC); group II: magnifying loupe tungsten carbide burs (MTC); group III: naked eye white stones (NWS); and group IV: magnifying loupe white stones (MWS). The initial surface roughness (Ra) T0 was evaluated using a profilometer, and the scanning electronic microscopy (SEM) technique. The metal brackets were bonded and debonded after 24 hours with debonding plier. After adhesive removal, Ra was evaluated again (T1) also the time spent on adhesive removal was recorded in seconds. The samples were finally polished by Sof-Lex discs and Sof-Lex spirals, and the third Ra evaluation was performed (T2).

RESULTS

The results of two-way mixed analysis of variance (ANOVA) showed that all burs increased surface roughness at T1 as compared to T0 (p < 0.001) with the highest Ra values shown in group III followed by group IV, group I, and group II. After polishing, no significant difference was noted in Ra values in group I and group II at T0 vs T2 (p = 1.000), while it was significant in group III and group IV (p < 0.001). Regarding the time required for adhesive removal, the shortest time was in group IV followed by groups III, II, and I, respectively.

CONCLUSION

The use of a magnifying loupe affects the quality of the clean-up procedure by reducing the enamel surface roughness and the time spent on adhesive removal.

CLINICAL SIGNIFICANCE

Using a magnifying loupe was helpful during orthodontic debonding and adhesive removal.

The effect of beer and milk tea on the shear bond strength of adhesive precoated brackets: An in vitro comparative study

Objectives

The objectives of this study were to evaluate the long-term effects of beer and milk tea on the shear bond strength (SBS) of adhesive precoated brackets and conventional adhesive on brackets.

Methods

The 150 metal brackets were bonded to maxillary permanent premolars and divided into two groups based on adhesive type: (1) Transbond PLUS Color Change Adhesive (TP) and (2) Flash-Free adhesive precoated (APC FF). The bonding processes were carried out exactly as recommended by the manufacturer. Each group’s samples were randomly divided into five subgroups with different immersion solutions and thermal cycles (n = 15): (1) at 24 h after bonding, (2) milk tea at 6 months, (3) milk tea at 1 year, (4) beer at 6 months and (5) beer at 1 year. The SBS differences between groups were analyzed using an independent-sample T test and one-way ANOVA with Dunnett’s T3 as a post hoc analysis.

Results

The SBS of TP were 20.66 ± 4.88 (X ± SD MPa), 23.14 ± 2.33, 17.54 ± 5.12, 24.64 ± 2.26, and 20.91 ± 6.19 for subgroups 1 to 5, respectively. The SBS of APC FF were 13.86 ± 4.14, 17.02 ± 4.04, 13.74 ± 4.40, 15.77 ± 4.11, and 16.21 ± 3.51 for subgroups 1 to 5 respectively. However, the SBS of APC FF was significantly lower than TP for all subgroups (p < 0.05). Beer showed a minor influence on the SBS (p > 0.05). The TP milk tea subgroup increased significantly throughout the 1-year thermal age period (p = 0.028). Both TP and APC FF showed higher values in the milk tea subgroups after 6 months of thermal age than in the beer subgroups (p < 0.05).

Significance

The APC FF group showed significantly lower SBS than the TP group. We found that milk tea increased the SBS in both the TP and the APC FF groups. However, beer had no significant effect on either group.

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.

Quantifying composite restoration removal and cavity re-preparation using novel region-specific volumetric analysis

OBJECTIVES

This in-vitro study investigated the effect of 400-405nm light used during removal of a composite restorations on volume of tooth tissue removed iatrogenically (IATR) and the volume of residual composite.

METHODS

Thirty unrestored premolar teeth obtained via a university tissue bank were evenly allocated to test and control groups; material removal with and without violet light. Three clinicians (blinded to the protocol) prepared class V buccal cavities in the teeth. The teeth were scanned using CEREC Omnicam and reallocated to another clinician prior to restoration and rescanning. The teeth were reallocated, and the restorations were removed prior to rescanning. Volumetric scan data was obtained on: changes in cavity volume; the volume of IATR; the volume of residual composite. Data were analysed using Shapiro-Wilk and Kruskal-Wallis tests to a significance of p<0.05.

RESULTS

Data showed that there is more IATR when the light was used with mean volume CAV2-over cut of (3.4 mm3, SD 4.22) whereas less IATR was seen when the light was not used (1.2 mm3, SD 1.00), (p<0.05). Data also showed that there is no significant difference in the overall volume of resin composite left when the light was used or not (p> 0.05). However when the light was used, less resin composite material was left around the margins of the cavities when compared to the no light group.

SIGNIFICANCE

This novel region-specific cavity analysis method reveals patterns of iatrogenic damage and retained composite which may hold clinical relevance. The use of violet light may result in more complete removal of composite at margins, but also increase IATR. Further research using the novel method is required to ascertain the repeatability and clinical significance of findings.

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.

Therapeutic properties of glass-ionomer cements: Their application to orthodontic treatment

Fluoride has been shown to be an effective agent in the prevention of caries during orthodontic treatment. Resin-modified glass-ionomer cements possess therapeutic anticariogenic properties acting as a fluoride reservoir and releasing fluoride into the environment, particularly at low pH where there is a threat of enamel demineralisation and white spot lesions (WSL's). Patient compliance to instructions in standard oral hygiene measures limits the success of caries prevention and the routine use of glass-ionomer cements can mitigate the lack of compliance, although RMGIC's are not a panacea against WSL's. The adhesion of GIC's to the enamel surface is a physicochemical bond rather than a mechanical bond which reduces the risk of iatrogenic damage to the enamel when bonding and debonding attachments. RMGIC's can be recommended as a bonding adhesive for all attachments but one needs to be selective when bonding molar attachments to avoid occlusal interferences as masticatory forces can be high in these areas.

Three-dimensional non-destructive visualization of teeth enamel microcracks using X-ray micro-computed tomography

Although the topic of tooth fractures has been extensively analyzed in the dental literature, there is still insufficient information about the potential effect of enamel microcracks (EMCs) on the underlying tooth structures. For a precise examination of the extent of the damage to the tooth structure in the area of EMCs, it is necessary to carry out their volumetric [(three-dimensional (3D)] evaluation. The aim of this study was to validate an X-ray micro-computed tomography ([Formula: see text]CT) as a technique suitable for 3D non-destructive visualization and qualitative analysis of teeth EMCs of different severity. Extracted human maxillary premolars were examined using a [Formula: see text]CT instrument ZEISS Xradia 520 Versa. In order to separate crack, dentin, and enamel volumes a Deep Learning (DL) algorithm, part of the Dragonfly's segmentation toolkit, was utilized. For segmentation needs we implemented Dragonfly's pre-built UNet neural network. The scanning technique which was used made it possible to recognize and detect not only EMCs that are visible on the outer surface but also those that are buried deep inside the tooth. The 3D visualization, combined with DL assisted segmentation, enabled the evaluation of the dynamics of an EMC and precise examination of its position with respect to the dentin-enamel junction.

Non-Invasive Optical Coherence Tomography Data-Based Quantitative Algorithm for the Assessment of Residual Adhesive on Bracket-Removed Dental Surface

The aim of this study was to quantitatively assess the residual adhesive on orthodontic ceramic bracket-removed dental surface. In orthodontic process, ceramic bracket was repeated debonding physically, then the adhesive remained on the dental surface. The residual adhesive caused a lack of adhesive strength between dental and ceramic bracket. Since commonly used adhesive in orthodontics is translucent, residual adhesive is hard to be detected with conventional microscopes. Therefore, 1310 nm center wavelength swept-source OCT system based on laboratory customized image processing algorithm was used for the precise detection of residual adhesive on tooth surface. The algorithm separates residual adhesive from dental surface by comparing the height of adjacent B-scan images, while providing color-scaled images emphasizing the thickness information of residual adhesive. Finally, the acquired results were compared with microscopic and adhesive remnant index scoring gold standards, while the comparison confirmed the potential merits and the improvements of the proposed method over gold standards.

Micron-scale human enamel layer characterization after orthodontic bracket debonding by intensity-based layer segmentation in optical coherence tomography images

In clinical orthodontic practice, fixed brackets are widely used for tooth movement and adjustments. Although years of research and development have improved the workability of fixed orthodontic brackets, there are still controversies regarding its plausible destructive influence on the enamel surface of tooth. This, in turn, makes the quantitative assessment of the enamel surface after specific orthodontic treatment procedures important in order to opt for the most effective treatment procedure. Through this study, we show the practical applicability of optical coherence tomography (OCT) as a non-ionizing and nondestructive assessment tool for measuring enamel loss after each step of orthodontic bracket bonding. Two-dimensional and volumetric OCT images are used for the evaluation of the tooth enamel. From the depth intensity profile analysis of cross-sectional OCT images, the changes in the individual internal layer thickness are calculated. A software algorithm was developed to evaluate the structural connectivity in the enamel for analyzing enamel loss on the tooth surface and for detecting enamel abrasion. An intensity-based layer segmentation algorithm is also developed to analyze and evaluate enamel wear in the tooth after each step. Using the proposed algorithms, the total enamel present after each treatment procedure was measured and tabulated for analysis.

Enamel Surface Damage following Debonding of Ceramic Brackets: A Hospital-Based Study

Methods

The current study includes 80 extracted premolars of human from the patient visiting for orthodontic treatment of Coorg Institute of Dental Sciences, Karnataka, India. The brackets were debonded using four different methods. The enamel surface damage after the procedure was assessed with the Enamel Surface Index (ESI); similarly, the Adhesive Remnant Index (ARI) score was used to determine the adhesive residual deposit. Scanning electron microscopy (SEM) was used to visualize better microporosities and micromechanical retention of adhesive remnants on the enamel surface. The normality of the data was tested using the Kolmogorov–Smirnov test. Depending upon the normality test result, the one-way ANOVA test or Kruskal–Wallis test was used to test the mean ESI and mean ARI differences among different debonding methods along with the appropriate post hoc tests. The necessary ethical clearance was obtained from the Ethics Committee of the institute.

Results

The ultrasonic scaler (US) technique led to more significant enamel surface damage, with 13 (65%) samples in the ESI scores III and IV against the satisfactory surface in 2 (10%) samples with the ligature cutter (LC) technique (ESI-I) reflecting LC as a better technique. The ESI scores (III and IV) for debonding plier (DP) and thermal method (TM) reflected a higher value in 12 (60%) and 10 (50%) samples and caused more damage to the enamel surface as compared to the LC technique. The ARI score was highest (ARI-1 = 40%) with the LC technique, followed by the US (ARI-1 = 20%), TM (ARI-1 = 15%), and DP (ARI-1 = 5%) methods. We have observed a significant association (p value <0.05) of the ARI score among four different debonding ways in terms of each tooth's residual adhesive after the bracket removal.

Conclusion

The result establishes the LC technique as a more acceptable one as it causes minimal harm to the debonded surface. The adhesive left on the debonded area is also minimum as compared to the other three methods tested. Therefore, it can be suggested as an ideal method.

Case Reports of Enamel Microabrasion Associated with At-home Dental Bleaching After Orthodontic Bracket Removal

Adequate removal of residual bonded materials from the enamel surface after orthodontic bracket debonding is critical, since any remaining composite may compromise enamel surface morphology and esthetics. The following clinical case reports present the association of at-home dental bleaching using 10% carbamide peroxide and the removal of residual bonded material using a super fine, tapered diamond bur followed by the use of an enamel microabrasion product after orthodontic bracket debonding. The proposed treatment considerably improved the esthetics and successfully removed the grooves created during the removal of the bonding composite, resulting in a smooth enamel surface.

Effects of Orthodontic Adhesives on Dental Enamel Color Alteration Using Chemically Cured and Light-Cured Composites

Objectives:

The purpose of this investigation was to evaluate the color alteration of dental enamel following the use of light-cured and chemically cured composites for bonding of metal brackets.

Materials and Methods:

Sixty extracted human premolars divided into five groups (n=12) were included in this study. Metal brackets were bonded using chemically cured (System 1+ and Unite) and light-cured (Transbond XT and Grengloo) composites. The control group remained untreated. After 72 hours of immersion in a staining solution and 24 hours of photoaging, the brackets were debonded, and adhesive remnants were cleaned using a 12-blade tungsten carbide bur and polished with Sof-Lex discs. The color was assessed at the baseline and after cleaning procedures in accordance with the CIE L*a*b (lightness, red/green, blue/yellow) color system. Statistical analyses were performed using paired sample t-test and one-way analysis of variance (ANOVA).

Results:

The L*, a*, and b* parameters showed a significant increase in all adhesive groups (P<0.001). The experimental groups showed significant color changes (P<0.05), and the mean ΔE ranged from 2.46 to 3.15 units. No significant difference was found between the ΔE of the adhesive groups (P>0.05).

Conclusion:

The enamel color change is influenced by bonding and debonding procedures. Chemically cured and light-cured composites have similar effects on dental enamel color alterations.

In vivo examination of enamel microcracks after orthodontic debonding: Is there a need for detailed analysis?

INTRODUCTION

Our aim was to assess changes in the number of enamel microcracks (EMCs) after removing metal brackets in teeth with and without visible EMCs before the bonding procedure.

METHODS

Before bonding, 13 patients having teeth with visible EMCs and 13 subjects whose teeth were free of EMCs were included in the study. All patients were asked to complete a questionnaire with a detailed medical history at the beginning of treatment and after removing metal brackets. The number of teeth with visible EMCs and the number of premolars without EMCs were recorded for each subject twice, that is, before bonding and after debonding, together with the tooth sensitivity assessments elicited by compressed air and cold testing.

RESULTS

The number of visible EMCs in premolars increased after removing metal brackets. EMCs were recorded in at least 25.0% of all evaluated teeth for the patients having teeth with and without visible EMCs at the beginning of treatment. However, the changes in the number of visible EMCs were not significantly different (P = 0.619) between the groups. For the subjects with visible EMCs, tooth sensitivity caused by cold was registered nearly 3 times more often after removing brackets compared with the patients without EMCs prior bonding.

CONCLUSIONS

Formation of EMCs was noticed after debonding. Changes in the number appeared to be similar for the subjects with and without visible EMCs before bonding. Higher incidence of EMCs was associated with more frequent tooth sensitivity perceptions after removing brackets.

Fluorescence-aided composite removal during lingual bracket debonding

OBJECTIVE

This report describes the fluorescence-aided composite removal during lingual bracket debonding with an ultraviolet light emitting diode flashlight. The purpose of this technique is to help clinicians in composite removal without enamel surface damage.

CLINICAL CONSIDERATIONS

The bracket debonding requires clinical attention in order to remove all composites and resins without enamel surface damage. Different protocols can be used in order to minimize the enamel damages and the excess bonding remnants. The fluorescence-aided composite removal permits to have an immediate visualization of the composites and adhesives, especially for the uneven lingual surfaces, of which the interindividual morphological variability is greater than the buccal surfaces.

CONCLUSIONS

The fluorescence-aided composite removal during lingual brackets debonding minimizes the risks described in literature and it is an easier, more accurate, reliable, noninvasive, inexpensive, and time-saving method.

CLINICAL SIGNIFICANCE

The application of this technique allows, with inexpensive flashlights, to remove all the composite on the lingual surfaces during debonding, without damaging the tooth and saving time.

Analysing the potential of hydrophilic adhesive systems to optimise orthodontic bracket rebonding

Introduction

Bond failure during fixed orthodontic treatment is a frequently occurring problem. As bracket rebonding is associated with reduced shear bond strength, the aim of the present investigation is to analyse the effect of different innovative rebonding systems to identify optimised rebonding protocols for orthodontic patient care.

Methods

Metallic brackets were bonded to the frontal enamel surfaces of 240 bovine lower incisors embedded in resin bases. Teeth were randomly divided into two major experimental groups: in group 1 a hydrophilic primer (Assure™ PLUS) was compared to commonly used orthodontic adhesives (Transbond XT™, BrackFix®, Grengloo™) and a zero control. In group 2 different rebonding systems were analysed using a hydrophilic primer (Assure™ PLUS), a methyl methacrylate-consisting primer (Plastic Conditioner) and a conventional adhesive (Transbond XT™). All teeth were tested for shear bond strength according to the DIN-13990 standard, the Adhesive Remnant Index and enamel fracture rate.

Results

The hydrophilic primer enhanced shear bond strength at first bonding (Assure™ PLUS 20.29 ± 4.95 MPa vs. Transbond XT™ 18.45 ± 2.57 MPa; BrackFix® 17 ± 5.2 MPa; Grengloo™ 19.08 ± 3.19 MPa; Meron 8.7 ± 3.9 MPa) and second bonding (Assure™ PLUS 16.76 ± 3.71 MPa vs. Transbond XT™ 13.06 ± 3.19 MPa). Using Plastic Conditioner did not seem to improve shear bond strength at rebonding (13.57 ± 2.94). When enamel etching was left out, required shear bond strength could not be achieved (Plastic Conditioner + Assure™ PLUS 8.12 ± 3.34 MPa; Plastic Conditioner: 3.7 ± 1.95 MPa). Hydrophilic priming systems showed decreased ARI-scores (second bonding: 2.63) and increased enamel fracture rates (first bonding: 55%; second bonding 21,05%).

Conclusions

Based on the present study we found that rebonding strength could be compensated by the use of hydrophilic priming systems. The additional use of a methyl methacrylate-consisting primer does not seem to enhance shear bond strength. No etching approaches resulted in non-sufficient bond strength.

Effects of polishing with paste containing surface pre-reacted glass-ionomer fillers on enamel remineralization after orthodontic bracket debonding

Surface pre-reacted glass-ionomer (S-PRG) technology allows for the release of multiple ions. This study was performed to investigate the remineralization of etched enamel after removal of the bracket using a novel paste containing S-PRG filler. Surfaces of polished enamel were etched with phosphoric acid and then subdivided into two regions. Bracket bonding resin was thinly applied to one region. After 24-hr immersion in artificial saliva, the bonding resin on the enamel surfaces was removed by grinding with tungsten carbide bur at low-speed, followed by polishing with one of four different polishing systems: (a) nonfluoridated paste (NF); (b) fluoridated paste (F); (c) S-PRG filler-containing paste (S-PRG); or (d) nonfluoridated plus S-PRG filler-containing paste (NF + S-PRG) (n = 15). The polished specimens were then immersed in an artificial saliva solution for 7 days. Nanoindentation testing of enamel surfaces was performed and their mechanical properties were compared. Representative specimens were examined with scanning electron microscope. In all specimens, the mechanical properties of the enamel surfaces were markedly degraded by acid etching. However, the mechanical properties of both regions (etched and resin-infiltrated enamels) showed recovery after polishing and 7-day immersion. Polishing with NF + S-PRG paste led to significant recovery of mechanical properties compared to polishing with NF or S-PRG paste alone, and remineralization was equivalent to that seen with F paste. Porous etched enamel surfaces were filled with a remineralization layer after each polishing procedure and 7-day immersion in all polishing groups. Polishing using NF + S-PRG paste can facilitate enamel remineralization after bracket removal.

Evaluation of Enamel Roughness in Vitro After Orthodontic Bracket Debonding Using Different Methods of Residual Adhesive Removal

Objective

The aim of the present study was to compare different techniques for resin remnant removal (RRR) after orthodontic bracket debonding and to evaluate alterations on the dental enamel caused by these methods. The null hypothesis tested was that there is no difference between RRR techniques in relationship the changes caused on the dental enamel.

Methods

A total of 75 bovine mandibular permanent incisors were used in the study. Brackets were bonded and debonded in each tooth in two experimental regions. Five RRR techniques were used in the experimental groups (n=15): Group 1-diamond bur (6-bladed), Group 2-diamond bur (12-bladed), Group 3-diamond bur (30-bladed), Group 4-aluminum oxide sandblasting (AOS), and Group 5-Er:YAG laser. Enamel surface was evaluated using profilometry, and surface roughness analysis was performed at three time intervals: before bracket bonding, after RRR techniques, and after final polishing. Qualitative analyses of the enamel surfaces were performed using scanning electron microscopy.

Results

Multiblade burs showed the best results, and the 30-bladed bur created a less irregular enamel surface. AOS caused greater enamel wear, and Er:YAG laser caused more surface irregularity.

Conclusion

The null hypothesis was rejected. The multiblade burs were the least harmful than the other techniques. Enamel surface roughness after using the 30-blade bur was similar to the original enamel. These results indicate that the type of bur tested (30-bladed) can be indicated to remove resin remnants after bracket debonding.

Do fluorescent agents alter the mechanical strength of orthodontic adhesives? An in vitro and clinical study

Background

Fluorescent agents are added to orthodontic adhesives with the aim of making them visible under ultraviolet (UV) light, which ensures the complete, safe removal of remnants after orthodontic treatment. However, it is necessary to evaluate if the mechanical strength of these materials is maintained. Therefore, this study evaluated whether the addition of fluorescent agents influences the shear bond strength and clinical performance of a UV light-sensitive adhesive system.

Methods

This study consisted of two stages: (1) In vitro phase: 40 human teeth were selected, divided at random into 2 groups (n = 20), according to the adhesive system used: UV group—adhesive with fluorescent agent, and control group—conventional adhesive. A shear bond strength test was performed using a DL 2000 universal testing machine, at a speed of 0.5 mm/min. The accessories were removed and an evaluation of the Adhesive Remnant Index (ARI) was carried out. (2) Clinical phase: 8 patients were selected and had their appliances bonded using the split-mouth design (160 teeth) with the same tested adhesive systems (UV, n = 80; control, n = 80). The patients were monitored for bonding failure for a period of 24 months. Statistical analysis was performed using the Independent t test, chi-squared tests, and Mann-Whitney test, at a level of significance of 5% and confidence interval of 95%.

Results

Regarding the in vitro phase, the shear bond strength test yielded similar results in the two groups (p > 0.05) and the ARI showed statistically significant differences between the groups with a score of 1 being the most frequent ARI for both groups (70%). In addition, there was no clinical difference in terms of bonding failure between the groups (p > 0.05).

Conclusion

The addition of fluorescent elements does not alter the mechanical strength and performance of the orthodontic adhesive and represents a viable alternative for clinical application.

Comparison of the Effects of Various Methods Used to Remove Adhesive from Tooth Surfaces on Surface Roughness and Temperature Changes in the Pulp Chamber

Objective

The purpose of the present study was to compare the effects of three methods of removing adhesive on enamel surface roughness and dental pulp temperature.

Methods

Ninety human maxillary premolars were randomly divided into three groups (n=30) according to the type of adhesive clean-up procedure: aluminum oxide-based burs, erbium-doped yttrium aluminum garnet (Er:YAG) laser, and tungsten carbide bur. The surface roughness of enamel was measured using a non-contact optical profilometer. After the first readings of surface roughness were measured (T1), orthodontic brackets were attached to the enamel surface with composite. The brackets on the teeth were debonded using bracket removal pliers. The residue of adhesive was eliminated from the enamel surface of the teeth by different procedures in each group. While removing adhesive from the tooth surface, the intrapulpal temperature rise was simultaneously measured using a thermocouple. One-way ANOVA and post-hoc Tukey HSD tests were used to analyze data with a significance level set at 0.05.

Results

The highest roughness average (Ra) values were observed for the Er:YAG laser group, with a significant difference with the aluminum oxide bur group and tungsten carbide bur group (p<0.001). Ra values for the aluminum oxide bur group were significantly lower than those for the other groups (p<0.001). Comparing the thermal changes in each group showed a significant decrease in the Er:YAG laser group, but a significant increase in two other groups.

Conclusion

Within the limitations of the present study, one-step finisher and polisher bur created the smoothest enamel surface, whereas Er:YAG laser the roughest. Tungsten carbide and aluminum oxide-based burs generated more heat than Er:YAG laser.

A Novel Etchant System for Orthodontic Bracket Bonding

Orthodontic treatment is widely used to correct irregular teeth and/or jaw discrepancies to improve oral function and facial aesthetics. However, it is frequently associated with enamel damage that include chipping, demineralisation, and white spot formation. So far, current bonding systems that can maintain shear bond strengths (SBS) suitable for clinical performance are unable to limit enamel demineralisation, adhesive remnants and damage caused on removal of brackets after treatment. This study reports a novel "safe enamel etch" clinically viable procedure that was accomplished via application of novel etchant pastes developed with β-tricalcium phosphate and monocalcium phosphate monohydrate powders mixed with citric acid (5 M) or phosphoric acid (37% PA) to yield BCA and BPA etchants respectively. Although enamel etched with clinically used PA gel yielded higher SBS than the BCA/BPA etchants, it exhibited greater adhesive remnants with evidence of enamel damage. In contrast, the experimental etchants resulted in unblemished enamel surfaces with zero or minimal adhesive residue and clinically acceptable SBS. Furthermore, the BPA etchant caused lower enamel decalcification with extensive calcium-phosphate precipitation. The study conclusively showed that BPA facilitated in vitro enamel adhesion without detrimental effects of the aggressive PA gel with potential for remineralisation and saving time at the post-debonding step.

Evaluation of a Fluorescence-aided Identification Technique (FIT) to assist clean-up after orthodontic bracket debonding

OBJECTIVES

To compare a fluorescence-aided identification technique (FIT) with a conventional light source (CLS) for removing composite during debonding of brackets with respect to time needed, composite remnants, and tooth substance loss.

MATERIALS AND METHODS

Twelve maxillary models with 10 bovine teeth each were digitally surface-scanned and metal brackets were bonded on each tooth with Opal Seal and Opal Bond. Two operators: an experienced orthodontist (A) and an undergraduate student (B) received six models each and were asked to remove the composite remnants with a tungsten carbide bur and Sof-Lex discs by both a conventional light source (CLS group, n = 3), and fluorescent inducing light (FIT group, n = 3). The time taken was recorded, and a postoperative scan was digitally superimposed on the preoperative scan to quantify number of teeth with composite remnants and volume and thickness of enamel loss and composite remnants. Chi-square test and independent t-tests were performed to compare methods with a significance level of 5%.

RESULTS

Compared to CLS, both operators needed significantly less time when using the FIT method and degree of enamel loss, height, and volume of composite remnants and total remaining composite remnants were significantly reduced. By FIT, the volume of enamel loss was significantly reduced for operator A only. Operator B removed the same enamel volume with either method.

CONCLUSIONS

Cleanup after orthodontic debonding with the FIT was superior regarding time needed and removal of composite remnants. Total enamel loss reduction was operator-dependent.

Impact of Fluorosis on the Tensile Bond Strength of Metal Brackets and the Prevalence of Enamel Microcracks

The objective of this in vitro study was to determine the effects of dental fluorosis on the tensile bond strength of metal brackets bonded to human teeth and to evaluate the changes in the tooth enamel surface after debonding. The study sample consisted of 68 recently extracted human upper premolars, which were divided into 2 groups: the fluorosis group (34 fluorosed teeth) and the control group (34 healthy teeth). Identical premolar metal brackets were bonded on the buccal surfaces of the teeth. Both groups were submitted to a tension test using a universal testing machine. The number and length of the enamel microcracks in the buccal surface of each tooth were determined before bracket bonding and after debonding using a stereomicroscope. The percentage adhesive remnant index (PARI) was calculated after debonding. The results showed that the tensile bond strength (TBS) of brackets bonded to fluorosed teeth was 21.08% lower than that of brackets bonded to healthy teeth (p < 0.0001). The length of the enamel microcracks on fluorosed teeth increased by 47.4% after debonding, whereas the control group showed an increase of only 12.6%. The PARI showed lower values for fluorosed teeth in comparison to the control group (p = 0.047). In conclusion, dental fluorosis has a negative impact on tensile bond strength and the length of microcracks formed after bracket debonding.

Enamel microcracks in the form of tooth damage during orthodontic debonding: a systematic review and meta-analysis of in vitro studies

Objectives

To evaluate and compare the enamel microcracks (EMCs) characteristics (qualitative and quantitative) in the form of tooth damage before and after debonding from human teeth of in vitro studies.

Eligibility criteria

Laboratorial studies evaluating EMCs characteristics before and after debonding metal and ceramic brackets from human teeth with intact buccal enamel.

Information sources

An electronic search of four databases (all databases of the Cochrane Library, CA Web of Science, MEDLINE via PubMed, and Google Scholar) and additional manual searches were carried out, without language restrictions. Studies published between 2000 and 2017 years were selected. Reference lists of the included articles were screened, and authors were contacted when necessary.

Risk of bias

The following six parameters were analyzed: blinding of examiner and outcome assessment, incomplete outcome data before bonding and after debonding, selective outcome reporting, and incomplete reporting of EMCs assessment.

Included studies

Out of 430 potentially eligible studies, 259 were screened by title and abstract, 180 were selected for full-text analysis, 14 were included in the systematic review. Seven studies were selected for the meta-analysis.

Synthesis of results

The results for EMCs characteristics were expressed as mean differences (MDs) with their 95 per cent confidence intervals (CIs), and calculated from random-effects meta-analyses. Debonding was associated with the increase in number (three studies, MD = 3.50, 95% CI, 2.13 to 4.87, P < 0.00001), length (seven studies, MD = 3.09 mm, 95% CI, 0.75-5.43, P < 0.00001), and width (three studies, MD = 0.39 µm, 95% CI, -0.01 to 0.79, P = 0.06) of EMCs. Considerable statistical heterogeneity was found for two forest plots evaluating the changes of number and length characteristics during debonding.

Conclusions

There is weak evidence indicating length and width of EMCs increase following bracket removal and the scientific evidence concerning quantitative evaluation of the number parameter before and after debonding is insufficient. However, there is a strong evidence that after debonding the number of EMCs is likely to increase.

Registration

No registration was performed.

An in vitro comparison of ultraviolet versus white light in the detection of adhesive remnants during orthodontic debonding

OBJECTIVES

To assess the effectiveness and efficiency of ultraviolet (UV) illumination compared to conventional white light in the detection of fluorescent-tagged adhesive remnants during orthodontic debonding.

MATERIALS AND METHODS

Orthodontic brackets were bonded to extracted human premolars using one of two bonding resins having fluorescent properties (Pad Lock, Reliance Orthodontics, Itasca, Ill; Opal Bond MV, Opal Orthodontics, South Jordan, Utah; n = 40 each). The brackets were then debonded and, in each adhesive group, half the teeth had the remaining adhesive resin removed under illumination using the operatory light and the other half using a UV (395 nm) light emitting diode (LED) flashlight (n = 20/group). Time for teeth cleanup was recorded. Follow-up images were obtained under a dissecting microscope using UV illumination, and the surface area of adhesive remnants was calculated. Effectiveness of adhesive removal was also assessed using scanning electron microscopy imaging. Analysis of variance and Kruskal-Wallis tests were used to analyze time and adhesive remnants, respectively.

RESULTS

Assessment using the dissecting microscope found groups using UV light during adhesive removal had statistically significantly lower amounts of adhesive remnants than groups using white light (P ≤ .01). Time for adhesive removal was significantly lower with Opal Bond MV adhesive using UV light when compared with the white light (P ≤ .01). Assessment by scanning electron microscopy showed that thin remnants of adhesive (<2 μm) remained undetected by UV illumination.

CONCLUSIONS

UV light is more effective and tends to be more efficient than white light in the detection of fluorescent adhesive during orthodontic debonding. Although there are limitations, the use of UV LED lighting is a practical tool that aids in adhesive detection.

Enamel gloss changes induced by orthodontic bonding

OBJECTIVE

The purpose of this study was to assess enamel gloss changes induced by orthodontic bracket bonding with a light-cured composite or a light-cured resin-reinforced glass ionomer cement.

SETTING

The Department of Biomaterials, School of Dentistry, National and Kapodistrian University of Athens, Greece.

DESIGN

Laboratory study.

METHODS

A total of twenty extracted upper human first premolars were included in this study and each tooth served as a control for itself. Their buccal surfaces were subjected to 60^o-angle gloss measurement (G%60) with a standardized and secure repeated analysis of the same site. After baseline evaluation, a bracket was bonded on the buccal surface of each tooth. Half of the specimens were bonded with acid-etching and a light-cured composite whereas the other half with a light-cured resin-reinforced glass ionomer cement without prior enamel conditioning. Gloss measurements were repeated after bracket debonding and removal of the composite/glass ionomer cement with an 18-fluted carbide bur. Gloss differences between the two measurement conditions (baseline and post-debonding) were analyzed through linear regression with standard errors derived using the bootstrap method. Level of significance was set at a < 0.05.

RESULTS

A statistically significant difference was detected between the tested groups for the outcome of interest. Teeth bonded with light-cured composite exhibited larger enamel gloss changes as compared to resin-reinforced glass ionomer cement (β = 0.74; 95% CIs: 0.10, 1.38; p = 0.02).

CONCLUSIONS

Bracket bonding with two common bonding protocols (acid-etching with a light-cured composite vs. no etching with resin reinforced glass-ionomer cement) and subsequently debonding and adhesive removal with an 18-fluted carbide bur induced enamel gloss changes.

Tooth wear during orthodontic treatment with fixed appliances: a systematic review

OBJECTIVES

Tooth wear, additional to the physiologic alterations of the dentition, may occur during orthodontic treatment. The objective of the present review was to investigate systematically the literature relevant to its progression in patients having undergone comprehensive orthodontic treatment.

DATA SOURCES

Search without restrictions in eight databases since inception and hand searching until October 2017 was performed.

DATA SELECTION

Studies evaluating tooth wear immediately before and after the completion of orthodontic treatment with fixed appliance were evaluated independently and in duplicate.

DATA EXTRACTION

Following study retrieval and selection, data on volumetric and surface tooth wear was extracted. Individual study risk of bias assessment was performed using the Risk Of Bias In Non-randomised Studies - of Interventions (ROBINS-I) tool, and the overall quality of the evidence was assessed with the Grades of Recommendation, Assessment, Development and Evaluation approach.

DATA SYNTHESIS

All three finally included studies reported wear of teeth during the period of treatment but were at serious risk of bias. Two of them investigated tooth wear by 3D volumetric measurements and one used grading scales. The mean volume reduction was 1.02 mm³ per tooth for the incisor group [95% Confidence Interval (CI): 0.84-1.20], 1.62 mm³ for the canines [95% CI: 0.8-2.38; I²= 96%; random effects method] and 0.95 mm³ for premolars and molars [95% CI: 0.84-1.07]. The overall quality of evidence limited the confidence in the observed estimates.

CONCLUSIONS

Varying degrees of tooth wear were reported after comprehensive orthodontic treatment. Further studies are needed in order to elucidate how much is associated with orthodontic treatment and/or physiologic alterations of the dentition.

Detection of residual resin-based orthodontic adhesive based on light-induced fluorescence

INTRODUCTION

This study evaluated the fluorescence of orthodontic adhesives using quantitative light-induced fluorescence-digital (QLF-D) images, and compared differences in the color characteristics of the fluorescence between adhesive and the adjacent tooth with that under white-light illumination in specimens containing residual adhesive of various thicknesses.

METHODS

Disc-shaped adhesive samples and samples comprising adhesive attached to extracted human teeth were prepared using Transbond XT, Blugloo, and Enlight, and they were ground to thicknesses ranging from 800 to 20 μm. Fluorescence and white-light images of the two types of specimens were taken with a QLF-D system. The color parameters for the fluorescence from the discs and the color difference (ΔE) between residual adhesive and the adjacent tooth were quantified in images using the CIE L*a*b* system.

RESULTS

The fluorescence color values of the discs differed significantly among the three adhesive products (P <  0.05). The ΔE values in fluorescence (ΔE_F) and white-light (ΔE_W) images for all three adhesives were lower for thinner residual adhesive specimens. The thickness of the adhesive could be perceived over a range of 50-100 μm for fluorescence images and 400-800 μm for white-light images (ΔE > 3.3). ΔE_F was significantly larger than ΔE_W for all of the residual adhesives, Blugloo specimens thicker than 100 μm, and Transbond XT and Enlight specimens thicker than 50 μm (P <  0.05).

CONCLUSIONS

Detecting and analyzing fluorescence signals can improve the ability to detect residual adhesive on a tooth and also provide thickness information.

Evaluation of a Fluorescence-aided Identification Technique (FIT) for removal of composite bonded trauma splints

BACKGROUND/AIM

Accurate removal of composite bonded titanium trauma splints (TTS) can be challenging. The aim of this study was to evaluate a Fluorescence-aided Identification Technique (FIT) compared with a conventional light source (CT) for removal of trauma splints regarding loss of tooth substance, residual composite, and time taken.

MATERIALS AND METHODS

Twenty maxillary models with six bovine teeth (13 - 23) were fabricated. An optical three-dimensional impression was taken and a TTS was applied from 12 to 22 with two bonding sites on every tooth under standardized conditions using an etch-and-rinse adhesive and resin composite. Two operators removed 10 splints each (5x FIT and 5x CT). For FIT, a 405 nm light-emitting headlamp was used. Time was recorded. A post-operative scan was superimposed on the pre-operative scan using OraCheck software. A qualitative and quantitative analysis of tooth defects and composite remnants was performed by two operators and statistically analyzed.

RESULTS

Compared with the CT, FIT led to significantly fewer and smaller enamel defects (mean volume: -0.04 mm³ vs -0.33 mm³ ) (P < 0.001), significantly less composite remained (mean volume: 0.02 mm³ vs 0.28 mm³ ) (P < 0.001), and the removal procedure with FIT was significantly quicker (mean: 162 seconds vs 268 seconds) (P < 0.001), CONCLUSIONS: FIT facilitated the removal of composite used to bond trauma splints leading to less time-consuming as well as less invasive treatment. It left fewer composite residues on enamel surfaces.

Enamel Roughness Changes after Removal of Orthodontic Adhesive

The aim of this study was to evaluate enamel roughness, quality of the enamel surfaces and time duration comparing different orthodontic adhesive removal protocols. Premolars were used to test three adhesive removal methods (n = 20): five-blade carbide bur, 30-blade carbide bur, and ultrasonic diamond bur. Bracket was bonded using Transbond^TM XT adhesive. Roughness with different parameters was measured before bracket bonding and after adhesive remnants removal. Micromorphological analysis of enamel surface (n = 5) was performed by SEM images and categorized in enamel damage index-"perfect"; "satisfying"; "imperfect"; and "unacceptable". Time was measured in seconds. All removal methods caused increased roughness in relation to R_a, R_q, and R_z parameters (X axis) comparing to healthy enamel surface. Enamel surface resulted from removal using five-blade burs was scored as satisfactory. Carbide bur groups decreased the roughness values of R_a, R_q, and R_z parameters on the Y axis and enamel surface was considered unacceptable. The 30-blade group increased symmetry (R_sk) and flattening (R_ku) parameters of roughness and surface was scored as unsatisfactory. Diamond bur removed adhesive in 54.8 s, faster than five-blade carbide bur. The five-blade bur group resulted in less enamel roughness than the 30-blade and diamond groups.

Orthodontic bonding and debonding induces structural changes but does not alter the mechanical properties of enamel

Background

The purpose of the study is to investigate the effect of the bonding procedure on the mechanical properties of human enamel.

Methods

A total of 20 extracted human premolars were included in this study, with the half of each tooth acting as its own internal control. Embedded and horizontally cut specimens were prepared, and two bucco-orally zones were separated. The first enamel zone of each tooth remained untreated. The opposing zone was subjected to simulated bonding and debonding, including etching with 37% phosphoric acid, bonding with primer and flowable composite resin, and subsequent removal of the composite with an adhesive removal bur. The properties tested were (a) elemental composition by energy-dispersive X-ray analysis, (b) mechanical properties of specimens by instrumented indentation testing (Martens hardness, elastic modulus, and elastic index), (c) enamel morphology by low-vacuum scanning electron microscopy, and (d) molecular composition by Raman microspectroscopy. Statistical analysis was performed by one-way mixed-effects analysis of variance at a = 0.05.

Results

No significant differences could be found in the mechanical properties (Martens hardness, elastic modulus, and elastic index) and elemental composition of intact and treated enamel, with the possible exception of Si traces, which were found only in the latter. Raman analysis revealed no differences between the two surface states while shallow grooves and parallel lines were found on the surface of treated enamel by SEM analysis.

Conclusions

Under the limitations of the conditions of the study, there were no mechanical properties’ alterations on enamel subjected to orthodontic bonding.

Enamel evaluation by scanning electron microscopy after debonding brackets and removal of adhesive remnants

Background

The bonding of accessories in the dental crown during the orthodontic treatment creates microporosities, thus promoting micromechanical retention of the adhesive to the enamel structure. After debonding brackets, at the end of the active orthodontic treatment, a certain amount of adhesive remnants must be mechanically removed from the enamel. The objective of this study was to compare, by means of scanning electron microscopy, three different methods to remove the adhesive remnants after orthodontic bracket removal.

Material and Methods

An experimental analytical study was conducted on human premolar specimens, extracted within a year or less. The preparation of the enamel was carried out with the application of 35% phosphoric acid and Transbond XT Light Cure Adhesive Primer® adhesive. Edgwise Standart prescription brackets, slot .022 “(Morelli Orthodontia) were glued to the enamel using Transbond XT® bonding resin. The brackets were placed on the center of the vestibular face of the clinical crown, and a 300-gram pressure was exerted against the surface of the enamel, measured with an orthodontic dynamometer. The brackets were debonded with adhesive removing pliers, and the samples were divided into groups, according to the protocol used for adhesive remnant removal: high-speed multi-laminated drill bit, low-speed multi-laminated drill bit, and low-speed glass fiber. After removal of the adhesive remnants, the samples went through scanning electron microscopy, obtaining electro micrographs with a magnification range of 150 X, 500 X, and 2,000 X.

Results

The tested method showed that the best effectiveness for the removal of the adhesive remnants after bracket debonding was the use of a tungsten carbide multi-laminated high speed, followed by the use of a tungsten carbide multi-laminated, low-rotation drill. The use of fiberglass drill alone has proved to be inefficient for clinical use, given the large amounts of adhesive remnants it leaves on the enamel.

Conclusions

All methods evaluated in this study proved to be inefficient for total removal of adhesive remnants from the enamel.

Key words:Dental enamel, microscopy, orthodontics.

Assessing abrasion of orthodontic surface sealants using a modified ophthalmic optical coherence tomography device

OBJECTIVE

Optical coherence tomography (OCT) is a clinical standard in ophthalmology. Currently, its application in dentistry is gaining increasing interest. In this study, we tested the possibility to use a modified commercially available spectral domain OCT (SD-OCT) to assess the layer thickness of orthodontic surface sealants.

MATERIALS AND METHODS

Reference samples of surface sealants for calibration and repeatability testing were measured using a micrometer screw. SD-OCT measurements were compared with micro-CT and light microscopic analyses. After validating the calibration of the SD-OCT, surface sealant layer thickness after aging (thermo cycling) and simulation of professional tooth cleaning (PTC) was assessed using the SD-OCT on 45 extracted teeth assigned to three test groups (n = 15 each): Light Bond™ Sealant, Pro Seal®, and Opal® Seal.

RESULTS

SD-OCT showed excellent repeatability and accuracy for measurements of surface sealant layer thickness. Compared with micro-CT, SD-OCT showed better accordance with the reference measurements. The analysis of surface sealants after thermo cycling and PTC revealed poor resistance of Light Bond after only aging and demonstrated substantial wear of all sealants after aging and PTC.

CONCLUSION

Imaging using commercially available ophthalmic SD-OCT might represent a suitable non-invasive methodology for longitudinal assessments of surface sealant layer thickness in vitro and in vivo.

CLINICAL RELEVANCE

SD-OCT might be a suitable non-invasive method for longitudinal assessments of surface sealant durability in clinical trials.

Enamel defects during orthodontic treatment

Background/Aim: Orthodontic treatment has an inherent potential for causing defects to enamel in the course of bonding and debonding procedures, interproximal enamel stripping and induce the presence of white spot lesions, enamel discoloration or wear. The aim of this study is to present the stages of orthodontic therapy associated with potential damage to enamel and list the enamel alterations observed in each stage. Material and Methods: A literature search was carried out in MEDLINEPubMed database for papers published up to and including February 2015. Results: Enamel loss is induced by cleaning with abrasives before etching, the acid etching process itself, forcibly removing brackets, and mechanical removal of composite remnants with rotary instruments. Loss of enamel or topographic changes in the form of cracks, scarring and scratches may occur. Clinicians may cause structural damage of enamel by interproximal enamel stripping. Additionally, the enamel surface may become demineralized due to plaque accumulation around the orthodontic attachments. Additional complications are enamel color alterations due to its microstructural modifications or discoloration of adhesive remnants and enamel wear due to contact with the brackets of the opposing teeth. Conclusions: Therapeutic procedures performed in the course of orthodontic treatment may cause irreversible physical damage to the outermost enamel. To avoid this, the orthodontic practitioner should take great care in every stage of the treatment and manage the enamel surface conservatively. Moreover, patients should follow an effective oral hygiene regimen. Given these conditions enamel damage during orthodontic therapy is eliminated and longevity of the dentition is promoted.

Efficiency of different protocols for enamel clean-up after bracket debonding: an in vitro study

Objective:

This study aimed to assess the efficiency of six protocols for cleaning-up tooth enamel after bracket debonding.

Methods:

A total of 60 premolars were divided into six groups, according to the tools used for clean-up: 12-blade bur at low speed (G12L), 12-blade bur at high speed (G12H), 30-blade bur at low speed (G30L), DU10CO ORTHO polisher (GDU), Renew System (GR) and Diagloss polisher (GD). Mean roughness (Ra) and mean roughness depth (Rz) of enamel surface were analyzed with a profilometer. Paired t-test was used to assess Ra and Rz before and after enamel clean-up. ANOVA/Tukey tests were used for intergroup comparison. The duration of removal procedures was recorded. The association between time and variation in enamel roughness (∆Ra, ∆Rz) were evaluated by Pearson's correlation test. Enamel topography was assessed by scanning electron microscopy (SEM).

Results:

In Groups G12L and G12H, original enamel roughness did not change significantly. In Groups G30L, GDU, GR and GD, a smoother surface (p < 0.05) was found after clean-up. In Groups G30L and GD, the protocols used were more time-consuming than those used in the other groups. Negative and moderate correlation was observed between time and (∆Ra, ∆Rz); Ra and (∆Ra, ∆Rz); Rz (r = - 0.445, r = - 0.475, p < 0.01).

Conclusion:

All enamel clean-up protocols were efficient because they did not result in increased surface roughness. The longer the time spent performing the protocol, the lower the surface roughness.

Enamel Resistance to Demineralization After Bracket Debonding Using Fluoride Varnish

The aim of this study was to evaluate the elemental content and morphology of enamel subjected to demineralization cycles after bracket debonding, adhesive remnant removal, and application of a fluoride varnish. 125 bovine teeth were divided into five groups (n = 25): 1) Intact enamel; 2) Intact enamel + demineralization cycles (DC); 3) Enamel after adhesive removal; 4)Enamel after adhesive removal + DC; 5) Enamel after adhesive removal + Profluorid + DC. The weight percentages of calcium (Ca), phosphorous (P) and fluoride (F) were calculated using energy dispersive X-ray spectroscopy (EDX). Samples were observed under scanning electron microscopy (SEM). Data were analyzed using Kruskal-Wallis and Mann-Whitney test. The weight percentages of Ca and P in Group 1 were significantly higher than Groups 2, 4, and 5. The weight percentages of Ca and P in Group 2 were significantly higher than Groups 4 and 5. Group 3 presented significantly higher percentages of Ca and P than Group 4. Group 5 showed a significantly higher percentage of Ca than Group 4. The presence of F was detected in Group 5. SEM images showed more signs of demineralization in Group 4 than Group 5. Fluoride varnish application may protect enamel from demineralization after bracket debonding.

On-line laser radiation controlled to the removal of adhesive on teeth after bracket debonding

BACKGROUND AND AIMS

After bracket debonding a correct removal of the adhesive from tooth surfaces without causing any iatrogenic damage to the enamel is needed. However, conventional techniques do not allow a selective removal process. The present article focuses on the removal of adhesive on teeth after bracket debonding by using laser radiation at 355 nm (third harmonic wavelength of a Q-switched Nd:YAG).

MATERIAL AND METHODS

Brackets were bonded to 10 extracted human premolars from young patients and removed after a storage period of 2 months. As real-time diagnostic technique, laser-induced breakdown spectroscopy (LIBS) elemental analysis was applied for precisely controlling the removal of the adhesive and morphological analysis of the etched surfaces was carried out by scanning electron microscopy (SEM).

RESULTS

LIBS technique allowed an on-line precise control in the adhesive removal process. SEM analysis revealed the capability of the 355 nm UV laser radiation to complete the removal of the adhesive on the tooth with no signs of damage on the enamel.

CONCLUSION

Laser ablation process at 355 nm monitored by the LIBS technique allows to carry out efficient removal of the adhesive on teeth.