Effects of different primers and colouring solutions on orthodontic bonding: shear bond strength and colour change.

OBJECTIVES: This in vitro study evaluated the effect of different colouring solutions and primer systems used in the bonding of brackets on enamel colour change and bond strength. MATERIALS AND METHODS: 120 premolar teeth were divided into four main groups; brackets were bonded with 37% orthophosphoric acid + Transbond XT Primer in Group 1, 3 M Single Bond Universal in Group 2, Transbond Plus SEP in Group 3, and G-Premio Bond in Group 4. Each group was divided into three subgroups, and the teeth were placed in a cup containing coffee and tea mixture, in a cup containing cola and in distilled water. A bond strength test was applied to all teeth. Colour measurements of all teeth were performed at 2 different times: before bonding and after the bond strength test. RESULTS: The average bond strength of the 37% orthophosphoric acid group was higher than that of the other groups. The effect of primer and solution groups on colour change was statistically significant (p = 0.001 and p = 0.023, respectively). CONCLUSIONS: In this study, the bond strength was clinically sufficient in all primer groups. The highest colour change was observed when the tea-coffee solution and Transbond Plus SEP primer were used. CLINICAL RELEVANCE: This study has identified enamel discoloration and bond strength from different colouring solutions and primer systems used for bonding braces, which can be used to inform clinicians and patients to achieve better treatment results.

Shear bond strength of orthodontic brackets bonded to high-translucent dental zirconia with different surface treatments: An in vitro study.

PURPOSE: The objective of this study was to compare the shear bond strengths of orthodontic brackets bonded to translucent dental zirconia samples which are anatomically accurate and treated with various surface treatments. METHODS: This in vitro study included 156 samples from 3 brands of high-translucent zirconia split into a control group and 4 surface treatment groups: 9.6% hydrofluoric acid etching, 50-micron aluminium oxide particle air abrasion, and 30-micron tribochemical silica coating (TBS) particle air abrasion with and without silane application. After surface treatment, all groups were primed with a 10-MDP primer and bonded to metal orthodontic brackets. Shear bond strength (SBS) was tested and results were compared between all groups. Data analysis consisted of a balanced two-factor factorial ANOVA, a Shapiro-Wilks test, and a non-parametric permutation test. The significance level was set at 0.05. RESULTS: Among all surface treatments, aluminium oxide particle abrasion produced significantly higher SBS (P≤0.002). Lava™ Plus zirconia samples had significantly higher SBS than Cercon® samples (P<0.0001). TBS surface treatment produced significantly higher SBS on Lava™ Plus samples than it did on the other zirconia brands (P=0.032). CONCLUSIONS: This study indicated that mechanical abrasion using aluminium oxide in combination with a 10-MDP primer creates a higher SBS to high-translucent zirconia than the bond created by tribochemical silica coating. Also, there was no significant difference in ARI regardless of zirconia brand or surface preparation.

The effect of different mechanical retention forms on shear bond strength of rebonding of ceramic brackets.

The objective of this study is to compare the shear bond strength (SBS) and the morphological characteristics and chemical compositions of the base surface of newly bonded and rebonded ceramic brackets with different mechanical retention bases. Sixty extracted human premolars were divided into the newly bonded and rebonded groups. Ceramic brackets with patterned, laser-etched, and particle-coated patterned bases were randomly bonded to the tooth samples in each group (n=10 per base type). The rebonded brackets exhibited significantly lower SBS than the newly bonded brackets (p<0.05). The main chemical composition of the brackets in both groups was aluminum on the energy-dispersive X-ray spectroscopy. Scanning electron microscopy imaging showed the presence of regular-shaped undercuts or irregular micro-undercuts on the bracket bases which mostly remained intact even after debonding and sandblasting, while coated particles disappeared. The rebonded ceramic brackets with mechanical retention bases exhibited clinically acceptable bond strength regardless of retentive forms.

Can antioxidant treatment replace delay in bracket bonding? An in vitro study.

BACKGROUND: Deterioration in shear bond strength has been reported after immediate bracket bonding following hydrogen peroxide bleaching. This study compared the effectiveness of three antioxidant agents, namely, alpha-tocopherol, green tea extract, and sodium ascorbate, in reversing the bleaching effect and as possible alternatives to delayed bonding. METHODS: A total of 105 extracted human premolars were arbitrarily assigned to 7 groups (n = 15 each), including group 1 as the unbleached control group and six experimental groups, which were bleached with 40% hydrogen peroxide in three sessions of 15 min each. In experimental group 2, bonding was performed immediately after bleaching, whereas in groups 3 and 4, bonding was delayed for 1 and 2 weeks, respectively; meanwhile, the specimens were immersed in artificial saliva at 37 °C. Groups 5, 6, and 7 were treated immediately after bleaching with 10% of alpha-tocopherol, green tea extract, and sodium ascorbate solutions, respectively, for 15 min. Specimens were processed using 500 thermal cycles between 5 and 55 °C, with a dwell time of 30 s after 24 h of bracket bonding, and then tested for shear bond strength. The adhesive remnant index was examined to evaluate fracture mode. One-way analysis of variance, Kruskal-Wallis H, and post hoc Tukey's honestly significant difference tests were used to compare the data. Significant results were subjected to pairwise comparisons with Bonferroni's correction-adjusted of p values ≤ 0.050. RESULTS: Shear bond strength was significantly lower (p < 0.001) in the immediate bonding and 1-week delay groups than in the control group. However, no significant difference was detected among the 2-week delay, antioxidant-treated, and control groups (p > 0.05). CONCLUSIONS: Application of 10% alpha-tocopherol, green tea extract, or sodium ascorbate for 15 min could restore shear bond strength after 40% hydrogen peroxide bleaching as an alternative to delay in bracket bonding.

Colour stability of 3D-Printed orthodontic brackets using filled resins.

OBJECTIVE: To determine the effect of common beverages and accelerated aging on the colour stability of filled resins, which could potentially be used for fabrication of 3D-printed orthodontic brackets. MATERIALS AND METHODS: GR-17.1 (shades A1, A2, and A3), and GR-10 Guide resins (pro3dure medical, Eden Prairie, MN) were printed on an Asiga MAX UV printer into discs 2 mm thick, with a diameter of 10 mm, and then post-print processed as per manufacturer's instructions. Discs were immersed in 5 mL of coffee, tea, red wine, or distilled water for 7 days. Another group was subjected to accelerated aging in accordance with ISO Standard 4892-2. Ten samples were produced per resin, per treatment condition. Colour measurements were taken on the discs before and after treatment using a spectrophotometer against white and black reference tiles to assess colour and translucency differences with the CIEDE2000 colour difference formula. RESULTS: While initial colour of the printed resin discs was acceptable, all resin groups underwent significant colour change during the experiment. Red wine and coffee produced the greatest colour and translucency change, followed by tea, with accelerated aging producing the least change in colour and translucency. CONCLUSION: The 3D-printed resins tested underwent significant changes in colour and translucency following exposure to endogenous and exogenous sources of staining, which may affect their acceptability for fabrication of aesthetic orthodontic brackets.

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.

Ability of a Blue Hemoglobin-Based Liquid as a Novel Technology to Stain Initial Enamel Demineralization: A Proof-of-Concept in vitro Study.

During orthodontic treatment, enamel demineralization can occur. Its early detection is the basis for efficient preventive measures to arrest or remineralize lesions. In the present study, the application of a novel blue hemoglobin-based liquid (BlueCheck) was evaluated as proof of concept for detection of artificially demineralized smooth surfaces. 60 samples from extracted human posterior teeth were randomly assigned to four groups (15 per group). In 30 of these samples (groups A and B), superficial enamel was removed to create a ground surface. On the surface of other 30 samples (group C and D), orthodontic metal brackets were bonded. On each surface, BC liquid was applied and rinsed with water after 3 min (baseline). All surfaces were checked by two independent observers for presence of blue areas. On each sample, one side was covered by nail varnish to protect this enamel part from demineralization. The samples were demineralized with lactic acid (pH 4.6) for 7 days (group A and C) and 14 days (group B and D), respectively. Mineral loss was determined using quantitative light-induced fluorescence after demineralization. BlueCheck dye was again applied on the samples and evaluated for presence of stained areas. Histological sections were prepared from randomly selected samples and lesion depth was measured. Kruskal-Wallis test was used for group comparison (α = 0.05). After demineralization, median ΔF value for all samples was -8.25% indicating the presence of an initial demineralization. The difference of ΔF values was not statistically significant between samples at 7 or 14 days of demineralization, nor for samples with and without orthodontic brackets (p = 0.13). At baseline, none of the sample surfaces showed discoloration, whereas a distinctive blue color was visible after demineralization in all samples exposed to acid-exposed areas, corresponding to 100% sensitivity. The internal control surfaces (without demineralization) did not show any staining, corresponding to 100% specificity. Histologically measured lesion depths ranged between 200 and 254 µm. In this in vitro study, staining of demineralized enamel surface areas were shown to be reliable. Based on our results, this easily applicable product seems useful to be an adjuvant method to clinical examination to monitor oral health during an orthodontic treatment on tooth surfaces after removal of dental biofilm.

Effect of cigarette smoke on aesthetic brackets: an in vitro study.

OBJECTIVE: The objective of this study was to evaluate the effect of cigarette smoke (CS) on physical and mechanical properties of ceramic, polycarbonate and alumina ceramic brackets. The null hypothesis tested was that aesthetic brackets would not be influenced by CS. METHODS: Ninety aesthetic brackets were allocated to three groups (n = 30): ceramic (GCE), polycarbonate (GCO) and alumina ceramic (GPS). Ten samples of each group were assigned to color and surface roughness analysis, performed before (T0) and after (T1) exposure to CS; and twenty samples were allocated into control and experimental groups (n = 10) (not exposed and exposed to CS, respectively) for shear bond strength test (SBS). Exposure to CS followed an adaptation of the method described by Le Mesurier. Colorimetric reading, surface morphology and roughness, SBS and adhesive remnant index (ARI) were assessed. Statistical analysis comprised independent and paired t-tests, ANOVA/Tukey and Fisher's exact tests (α = 0.05). RESULTS: Changes were observed in brackets' color (NBS: GCE = 2.4; GCO = 1.9; GPS = 2.1), surface roughness (ΔRa: GCE = 1.1 ± 0.8 µm; GCO = 1.9 ± 1.5µm; GPS = -0.3 ± 0.1 µm / ΔRz: GCE = 1.4 ± 1.0 nm; GPS = -0.5 ± 0.1 nm); and SBS (GPS - experimental = 221.8 ± 48.6 N) after exposure to CS (p< 0.05). CONCLUSIONS: Exposure, in vitro, of aesthetic brackets to CS resulted in changes of color to darker and more opaque shades, surface roughness alterations, and higher SBS values. ARI scores were not associated with exposure to CS.

Mechanical characterization of aesthetic orthodontic brackets by the dynamic indentation method.

The objective of this study is to investigate the mechanical properties, such as the dynamic hardness and indentation elastic modulus, of commercially available aesthetic orthodontic brackets, such as ceramic and plastic brackets, by the dynamic micro-indentation method. Five ceramic brackets, which were made of alumina (both monocrystalline and polycrystalline forms) or zirconia, and two plastic brackets, which were made of glass fiber-reinforced polycarbonate or polyamide, were tested. There were significant differences in the mechanical properties of the monocrystalline and polycrystalline alumina brackets. The mechanical properties of the glass fiber-reinforced plastic bracket were significantly superior to these of the non-glass-fiber-reinforced plastic bracket. The differences in the crystal structures of the ceramic brackets surface affected the dynamic hardness and indentation elastic modulus. Furthermore, the short glass fibers contained in the plastic bracket might contribute to the improvement of the mechanical properties.

Innovative Application of Diathermy in Orthodontics: A Case Report.

INTRODUCTION: Several strategies have been proposed in the literature to accelerate tooth movement, many of which are invasive and have numerous side effects, such as surgical techniques (corticotomy and piezocision technique). This research investigates to what extent diathermy can accelerate the orthodontic alignment phase. MATERIALS AND METHODS: A patient with lower teeth crowding index of the same magnitude was selected. The orthodontic treatment with Nickel-Titanium (NiTi) thermal arc 0.015 in the lower arch was performed, associated with a weekly application of diathermy using the intraoral handpiece. The total duration of treatment was three weeks. During each session, an intraoral transducer was employed to stimulate the hard and soft tissues of the left dental hemiarch, which was also orthodontically aligned like the right one. RESULTS: Comparing the tooth movements of four elements of the two hemiarchies, it was found that, overall, the two teeth examined on the treated side underwent a more significant number of changes than on the untreated side, although not by a significant amount. CONCLUSIONS: The use of diathermy, according to the authors, is a non-invasive approach that may speed up the orthodontic alignment phase and reduce treatment duration, resulting in a lower risk of caries, gingival recessions, root resorptions, and patient compliance improvement, without side effects. Further studies and an adequate sample size will be needed to confirm the findings.

Efficacy of Photobiomodulation Therapy Versus Soft Acrylic Wafer for Reduction of Pain Associated with Orthodontic Metal Bracket Removal: A Clinical Trial.

Objective: This study compared the efficacy of photobiomodulation therapy versus soft acrylic wafer for reduction of pain associated with orthodontic metal bracket removal. Background: It has been demonstrated that different methods of bracket removal are associated with different levels of pain. Photobiomodulation decreases the level of pain due to its biological effects. Methods: This split-mouth randomized clinical trial evaluated 28 orthodontic patients. The four quadrants in each patient were randomly assigned to four groups of diode laser (940 nm, 31.7 J/cm2 energy density, 1.7 cm2 spot size, 300 mW power, continuous-wave, contact mode) irradiated to the buccal and palatal surfaces of each tooth, soft acrylic wafer, laser in off mode (placebo), and no intervention (control). The severity of pain experienced by patients was assessed immediately after bracket removal from each tooth using a visual analog scale. Data were analyzed using the generalized estimating equation (α = 0.05). Results: The mean pain score in the soft acrylic wafer (p = 0.017), control (p < 0.001), and placebo (p < 0.001) groups was significantly higher compared with the laser group. Gender (p = 0.209), age (p = 0.095), and laterality (right/left quadrant; p = 0.383) had no significant effect on the pain score. The pain score in the mandible was significantly lower compared with the maxilla (p = 0.027). The first and second premolars had significantly lower pain scores (p < 0.05). Conclusions: Within the limitations of this study, photobiomodulation therapy and soft acrylic wafer can both decrease the pain associated with metal bracket removal, but laser is more effective.

Evaluation of the photodynamic therapy with riboflavin and curcumin on shear bond strength of orthodontic bracket: An in vitro study.

AIM AND OBJECTIVES: The aim of this study was to evaluate the effect of antimicrobial photodynamic therapy (aPDT) with riboflavin and curcumin on the shear bond strength (SBS) of the orthodontic brackets. METHOD AND MATERIAL: A total of 45 human premolar teeth were used in this study. All teeth were examined under a stereomicroscope. The samples were divided into 3 groups including no intervention (control group), aPDT with riboflavin and 460 nm LED and aPDT with curcumin and 460 nm LED. After aPDT procedure, orthodontic brackets were bonded to enamel surfaces. Then, the samples were thermocycled for 3000 cycles. The brackets were then debonded using a universal testing machine. The adhesive remnant index (ARI) score was assessed. ANOVA with Post-hoc test was used to compare the SBS values between groups. RESULTS: The highest SBS mean value was presented in curcumin group (25.95±3.68) whereas, the lowest SBS mean value was observed in riboflavin group (22.19±4.73). The mode of failure was mostly score 1 and score 2 in all groups. There was no significant difference in SBS values and ARI score between groups. Scanning electron microscope images of the curcumin and control groups showed the honey comb structure, while the microscopic view of the riboflavin group lacked this structure and had less porosity and irregularity after etching. CONCLUSION: Riboflavin and curcumin mediated antimicrobial photodynamic therapy both have acceptable bond strength of the orthodontic brackets and can be used before bonding to reduce inflammation and elimination of microbial biofilms.

Shear bond strength of orthodontic molar tubes to composite restoration bonded with particular adhesives after different surface pre-treatments.

OBJECTIVE: To evaluate in vitro the shear bond strength of orthodontic molar tubes to composite restoration bonded with particular adhesives after different surface pre-treatments. SETTING AND SAMPLE POPULATION: The sample population is 60 extracted molars. MATERIALS AND METHODS: After the teeth were thermocycled, they were randomly divided into six groups according to the adhesive and various surface pre-treatments that had been applied. The surface pre-treatments included sandblasting with 50-µm aluminium oxide particles and roughening with diamond bur and 37% phosphoric acid. Transbond XT Adhesive Primer (3M Unitek) (TXT) and Assure Plus (Reliance Orthodontic Products) adhesives were used in the study. Following the application of the adhesives, the brackets were bonded to the surfaces of the teeth. Shear bond strength was measured using a universal testing machine. Data were analysed with one-way ANOVA and LSD tests (P = .05). The adhesive remnant index (ARI) was determined using a stereomicroscope. Data from the ARI scores were submitted to Pearson's chi-squared test (P = .05). RESULTS: The highest shear bond strengths were obtained in the Assure Plus group 15.05 ± 3.72 MPa after sandblasting (P < .05). The lowest shear bond strengths were found in the TXT group (7.52 ± 2.89 MPa; P < .05). Sandblasting and bur pre-treatment for TXT and Assure Plus adhesives increased shear bond strength in both of them. There were no significant differences in the ARI scores between the groups (P > .05). CONCLUSION: Sandblasting and roughening pre-treatment can increase the bond strength of teeth with composite restoration. Assure Plus is also more effective than conventional adhesive systems.

Natural and synthetic photosensitizers activated by photodynamic therapy on enamel reconditioning rebonded to metallic brackets: an in vitro study.

OBJECTIVE: To evaluate the bond efficacy and failure rates of rebonded metallic brackets after enamel reconditioning with chemical 37% phosphoric acid (PA) and natural and synthetic photosensitizers activated by PDT. MATERIALS AND METHODS: A total of 50 non-cavitated, and cautiously extracted human premolars were congregated after sample size calculation. The enamel exterior was etched, washed, dried for adhesive application, and cured. Metallic brackets were then oriented and adapted to enamel surface using composite. Later, brackets were debonded from the surface via a Weingart plier. Enamel was finished for ensuing surface reconditioning. Ultimately, specimens were randomly distributed into five groups (n=10). Enamel surface before rebonding was reconditioned with curcumin photosensitizer (CP), riboflavin photosensitizer (RP), rose bengal photosensitizer (RBP), methylene blue photosensitizer (MBP), and 37% PA (control) respectively. After following reconditioning protocol, brackets were rebonded to the enamel exterior employing a composite adhesive system. Then, specimens were subjected to the universal testing machine for analyzing shear bond strength (SBS), and bond failures were predicted using an ARI index. One-way ANOVA and Tukey multiple comparison tests were used for statistical analysis at a variance value of p < 0.05. RESULTS: Enamel reconditioned with 37% PA demonstrated the highest SBS for bracket rebonding, and the lowest SBS was presented by CP actuated by PDT. Enamel reconditioned with RP and RBP corroborated the analogous SBS outcome to 37% PA. Likewise, enamel surface treatment with MBP revealed a statistically significant result to CP for metallic bracket rebonding. The most prevalent failure scores anticipated among groups were 0 and 1 indicating an adhesive failure with the exemption of group 5 (control) that encountered more score 2 cohesive failure on debonding metallic brackets from enamel exterior. CONCLUSIONS: Rose bengal and riboflavin photosensitizers activated by photodynamic therapy with low ARI scores have the potential to be used as viable enamel reconditioning alternatives to 37% phosphoric acid for rebonding metallic brackets.

Effect of blue light plus chlorhexidine therapy on Streptococcus mutans biofilm and its regrowth in an in vitro orthodontic model.

INTRODUCTION: Fixed orthodontic appliances create areas of stagnation for dental biofilms and make it difficult to clean the teeth; therefore, there is a risk of developing incipient caries lesions during the orthodontic treatment. The objective of this study is to determine if the combination of 2 different therapies, phototherapy by blue light (BL) and the antimicrobial 0.12% chlorhexidine (CHX) on enamel, orthodontic brackets, and elastics, would reduce or inhibit mature Streptococcus mutans biofilms and their regrowth on these substrates 24 hours after the application of the treatment; and if this treatment would interfere with bracket adhesion to the enamel. METHODS: Biofilms of S. mutans UA159 were formed for 5-days over samples composed of a bovine enamel, orthodontic bracket, and orthodontic elastic. Then, the specimens were treated with 0.89% NaCl for 1 minute, BL for 12 minutes (72 J/cm2), 0.12% CHX for 1 minute, and BL for 12 minutes, followed by 0.12% CHX for 1 minute (BL+CHX). Biofilm was evaluated by colonies forming units and dry weight immediately after treatments and 24 hours after treatments (regrowth). The pH of the spent media was measured on the fifth and sixth days. Biofilm formation on the samples after the treatments and regrowth was visually evaluated by confocal laser scanning microscopy. Shear bond strength (SBS) between bracket and enamel was evaluated using a universal testing machine at a crosshead speed of 1 mm/min. After bonding, specimens were thermocycled (500× at 5-55°C), treated, and thermocycled again. RESULTS: After 5 days of biofilm formation, BL+CHX significantly reduced the bacterial viability on enamel compared with NaCl (P = 0.004) and BL (P = 0.014). For bracket and elastic, all the treatments resulted in similar bacterial viability (P ≥0.081). In the regrowth, CHX and BL+CHX significantly reduced the bacterial viability in the enamel compared with the NaCl (P ≤0.015) and BL (P ≤0.013). For bracket, BL+CHX significantly reduced the bacterial viability compared with NaCl (P = 0.008) and BL (P = 0.009). For the elastic, BL+CHX eliminated the biofilms from the substrate. CHX and BL+CHX significantly reduced the bacterial viability 24 hours after treatment for all substrates (P ≤0.05). The media pH significantly increased when samples were treated with CHX and BL+CHX (P ≤0.001). Confocal laser scanning microscopy images visually showed an abundant quantity of red cells in the samples treated with BL+CHX. There was no difference in the SBS between the treatments (P ≥0.932). CONCLUSIONS: The association between BL and CHX reduced S. mutans biofilm and its regrowth on an in vitro orthodontic model and did not influence the bonding strength between bracket and enamel.

Colour stability of 3D-printed resin orthodontic brackets.

OBJECTIVE: To evaluate the colour stability of polymeric resins that could be used to 3D-print orthodontic brackets. DESIGN: In vitro, laboratory study. MATERIALS AND METHODS: Disc-shaped specimens were fabricated via 3D printing using three resins: Dental LT; Dental SG; and Clear. Five conditions were evaluated for each resin (n = 10 per treatment per resin) to assess its corresponding effect on colour and translucency: immersion in (1) red wine, (2) coffee, (3) tea and (4) distilled water (control), and (5) exposure to accelerated aging. Colour and translucency measurements were made before and after exposure using a spectrophotometer. Mean colour differences (ΔE00) and changes in translucency parameter (ΔTP00) were calculated for each sample using the CIEDE2000 colour difference formula. RESULTS: Statistically significant effects of the resin material, the treatment condition and interactions effects of material and condition were observed for ΔE00 and ΔTP00 (P < 0.001). The most pronounced changes in colour (ΔE00) were a result of the staining effects of wine on all three resins, ranging from 14.5 ± 0.6 to 20.8 ± 1.2. Dental LT, Dental SG and Clear resins all showed changes in colour when exposed to certain staining agents. Dental SG and Clear resins exhibited changes in colour with aging, while the colour of Dental LT resin remained stable with aging. CONCLUSIONS: The colour changes of the resins investigated does not support their use in 3D-printed aesthetic bracket applications.

The lingual enamel morphology and bracket shear bond strength influenced by Nd:YAG laser and aluminum oxide sandblasting preconditioning.

OBJECTIVES: This study aimed to investigate the influence of Nd:YAG laser and aluminum oxide sandblasting on the shear bond strength (SBS) of lingual brackets and to optically analyze the behavior of the enamel morphology. MATERIALS AND METHODS: Thirty-five bovines' incisors teeth were divided into 5 groups (n = 7), according to the surface preconditioning: G1, control group; G2, Nd:YAG laser; G3, laser + aluminum oxide sandblasting (Al2O3); G4, Al2O3; and G5, Al2O3 + laser. All groups had lingual brackets bonded and shear debonded after 72 h. SBS values were analyzed, and the enamel morphology was evaluated by optical coherence tomography (OCT) and scanning electron microscope (SEM), before and after preconditioning surface. The optical attenuation coefficient (α) analysis was obtained from OCT images. Data analysis used the ANOVA test, followed by post hoc Tukey, Kruskal Wallis, and post hoc Dunn tests (significance of 5%). RESULTS: The SBS values presented similarly among groups, but the value of α showed statistical difference (p-value = 0.0124) between G3 and G5 with the others. Optical analyses indicated a melting on the enamel that suffered laser irradiation for G2 and G5 and crystal surface disorganization for G4. Sandblasting partially removes the melting of the laser effect (G3). CONCLUSION: The sandblasting is a dispensable step for bonding lingual brackets, and the melting of the enamel after laser irradiation does not compromise the bracket adhesive resistance. CLINICAL RELEVANCE: The Nd:YAG laser became an interesting tool to prevent caries and decrease prevalence of white spot lesions in orthodontic treatments, without systemic effects in patients with genetic high risks of caries.

Comparison of rate of orthodontic tooth movement in adolescent patients undergoing treatment by first bicuspid extraction and en-mass retraction, associated with low level laser therapy in passive self-ligating and conventional brackets: A randomized controlled trial.

BACKGROUND: Low Level Laser Therapy (LLLT) is one of the various interventions to accelerate the rate of Orthodontic Tooth Movement (OTM) in adolescent patients who are undergoing en-mass retraction after all first bicuspid extractions. OBJECTIVES: To assess the efficacy of LLLT in increasing the rate of OTM. MATERIALS AND METHODS: Setting and sample population: Institutional Department of Orthodontics and Dentofacial Orthopaedics. Participants, study design and methods: 65 Patients requiring all first premolar extractions were randomly allocated to three groups. Two groups (Comprising of passive self-ligating brackets and conventional brackets) were treated with LLLT and one group served as the control (conventional brackets). The allocation ratio was 1:1:1.32. Eligibility criteria: adolescent patients with sound and healthy permanent dentition with Little's Irregularity Index<5mm. MAIN OUTCOME: rate of tooth movement in mm/month. Randomization and blinding: computer-generated random allocation sequence; only the data analyser was blinded by coding the digital models. Patients were reviewed once every month till the completion of space closure. STATISTICS: data normality was checked using Shapiro-Wilks test and Q-Q Plot. Parametric tests were applied for the inferential statistics (ANCOVA) with Dunnett's t test being used for post hoc analysis. RESULTS: There was a statistically significant enhancement in the rate of OTM in the 2 experimental groups (0.68/0.67mm/month in the right and left side of the maxilla and 0.66/0.65mm/month in the right and left side of the mandible) when compared with the control group (0.48mm/month in the maxilla and 0.48mm/month in the mandible) (P<0.05), but when the 2 experimental groups were compared no difference was observed (P>0.05). No serious harms were reported. CONCLUSION: A significant increase in the rate of OTM was observed with the application of LLLT. No difference was observed in the rate of OTM when comparing different ligation methods treated with LLLT. REGISTRATION: National Trial Registry (CTRI No- CTRI/2018/04/013156). Protocol was not published before trial commencement.

Green tea extract solutions can control bacterial biofilms formed on space maintainers.

BACKGROUND: Microorganisms in the mouth are protected from negative environmental conditions by forming biofilms; however, the use of anti-plaque agents in children is not preferred due to toxic side effects. Green tea has been reported to have anti-microbial and anti-dental caries properties. AIMS: The aim of this study was to assess the ability of green tea extract to prevent the formation of biofilm on the teeth of children using space maintainers. METHODS: Bacteria were isolated from samples obtained from children aged between 8 and 10 years. The micro-titer plate method and Congo red agar were used to assay biofilm formation. Green tea leaves were obtained from Rize, Turkey. Methanol, hexane and distilled water were used for preparing the extracts. The effects of green tea extract and chlorhexidine on biofilm formation were examined using scanning electron microscopy. RESULTS: Presence of S. mutans 3,3, S. anginosus 2.1.b, S. dysgalactie 6.1.4.1, and E. faecium 10.2. was measured in the biofilm samples. The extracts showed a bacteriostatic effect on the test bacteria, and among the green tea extracts, the methanol extract was found to exhibit the highest efficacy against biofilm formation by S. mutans 3.3. CONCLUSION: Green tea extract showed good efficacy in controlling bacterial growth, and is recommended as a better-tasting alternative for daily oral hygiene due to a lack of known side effects.

Colour change of ceramic brackets with the use of coloured beverages in adolescent patients: A randomized clinical trial.

OBJECTIVE: To clinically evaluate colour change of ceramic orthodontic brackets with the use of coloured beverages as ceramic brackets' resistance to discoloration has become a major concern. MATERIAL AND METHODS: A prospective two parallel groups-split mouth randomized trial with a 1:1 allocation ratio. Two equal groups including 40 adolescent patients from the orthodontic department (Faculty of Dentistry, Mansoura University, Egypt), scheduled for maxillary premolar extractions were bonded with 2 types of mono-crystalline ceramic brackets: Type 1 (Inspire ICETM) and Type 2 (Radiance PlusTM). Participants in each group were asked to rinse with either black tea or Cola. After extraction, the colour of the 80 debonded brackets was compared to that of 20 control brackets from each type by spectrophotometer according to the international standard CIELAB colour space (CIE L*a*b*). The latter consists of three coordinates: L* (lightness value), a* and b* (the colour channels). The total colour difference ΔE* is the distance between two colours in this three-dimensional colour space. The colour change was also assessed by digital image analysis according to the RGB model. RESULTS: Type 1 brackets showed mean ΔE* values of 2.24±0.25 in black tea and 1.76±0.1 in Cola groups (P<0.001), while Type 2 brackets showed means of 1.99±0.15 in black tea and 1.56±0.1 in Cola groups (P<0.001). The mean RGB values were 174.3±12.02 in black tea and 185.6±6.9 in the Cola groups of type 1 brackets (P<0.001), while were 166.5±17.8 in black tea and 190.8±8.9 in Cola groups of type 2 brackets (P<0.001). CONCLUSION: Black tea showed more significant effect than Cola on the two bracket types. Bracket type affected the colour change in each beverage group.