Direct versus fully digital indirect bracket bonding: a split-mouth randomized clinical trial on accuracy.

OBJECTIVES: The primary aim is to assess differences in accuracy of orthodontic bracket positioning between fully digital indirect bracket bonding (IDB) and conventional direct bracket bonding (DBB). The secondary aims are to assess differences in bracket bonding failures, bracket repositioning need, clinician experience and patient satisfaction. MATERIALS AND METHODS: This prospective study was designed as a split-mouth randomized clinical trial. In total, 35 patients were analyzed with a six month follow-up period. Translational and orientational deviations from the planned bracket position were determined. Clinician experience and patient satisfaction were evaluated by means of a survey. RESULTS: The difference in translation was 0.34 mm (95% CI: 0.238-0.352, p = 0.017), the difference in orientation was 4.80˚ (95% CI: 3.858-5.727, p < 0.001), both in favour of IDB. IDB showed significantly more immediate (IDB: 3.9%, DBB: 0%) and late (IDB: 5.4%, DBB: 2.5%, p = 0.008) bonding failures. Clinicians and patients experienced a shorter clinical chair time with indirect bonding over direct bonding. CONCLUSIONS: IDB bracket positioning leads to significant smaller translation and orientation deviations from digital IDB planning, than DBB bracket positioning. However, IDB leads to more immediate bonding failures than DBB. The majority of patients preferred IDB over DBB, due to a shorter clinical chair time. CLINICAL RELEVANCE: This study adds to the knowledge of IDB in orthodontics and contributes to evidence on this technique. This evidence is applicable in everyday orthodontics, with respect to patient satisfaction and technical limits of IDB. The trial was registered in the Dutch Trial Register and the International Clinical Trials Registry Platform (ICTRP) of the World Health Organization (WHO), number NL9411.

Effect of fluoride varnish in combination with simulated oral environment on enamel-bracket shear bond strength.

To determine the effect of fluoride varnish application combined with a simulated oral environment prior to bracket bonding on the shear bond strength (SBS) between brackets and tooth enamel. Sixty de-identified, extracted teeth were grouped to either receive or not receive fluoride varnish and then stored for 7 days at 37 °C in phosphate-buffered saline (PBS) solution or PBS combined with three 15-min cycles/day in a demineralizing solution to simulate pH variation following meals. Subsequently, brackets were bonded and after 24-h dark cure at 37 °C, debonded using shear forces in a simulated oral environment. The maximum shear force was used to calculate SBS, and the adhesive remnant index (ARI) was determined by image analysis of photos of the bracket mesh pad after debonding. A statistically higher SBS (10.16 MPa) was observed when fluoride varnish was applied prior to storage in PBS + demineralizing solution compared to SBS (6.38 MPa) following storage in the same solution without varnish application. Based on 37% effect size, this difference is also clinically relevant. In contrast, no significant differences in SBS were observed with varnish application combined with PBS with no demineralizing solution or between storage solution alone. Moreover, there was no significant difference in ARI due to varnish combined with either storage method or storage solution only. Results suggest varnish application prior to bracket bonding in combination with simulated oral environment that included acid exposure is beneficial in maintaining higher SBS between bracket and enamel. Despite higher SBS, adhesive remaining on enamel did not increase.

Accuracy of bracket position using thermoplastic and 3D-printed indirect bonding trays.

AIM: The positional accuracy of bracket placement planned through tooth setup vs actual placement was evaluated by means of conventional thermoplastic indirect bonding trays and customized 3D-printed indirect bonding trays. MATERIALS AND METHODS: A total of 280 bracket positions placed on the crowns of 10 dental plaster models were evaluated. The manual setup method and a thermoplastic indirect bonding tray were used for the manual group. For the CAD/CAM group, the bracket was positioned using a digital setup and a corresponding 3D-printed tray. The positional accuracy of the bracket placement on the duplicated gypsum model using the trays was evaluated by means of 3D software. Six errors of bracket position (height, depth, mesiodistal, torque, rotation, and tip errors), including linear and angular errors, were measured. Differences in variables were compared across subgroups using the independent t test or the Mann-Whitney U test. RESULTS: Only the height error differed significantly (P < 0.05) between groups (manual: 0.2 mm; CAD/CAM: 0.12 mm). For both incisors and molars, the manual group showed significantly greater height errors than the CAD/CAM group (P < 0.05). The analysis of variance of the position error to the whole bracket showed statistically significant differences between tooth positions, linear measurements, and angular measurements (P < 0.05). CONCLUSION: A 3D-printed indirect bonding tray showed accuracy similar to that of conventional methods for bracket placement, with slightly greater bracket height accuracy. Further studies should strive to improve accuracy in terms of tooth positions.

The Use of Lasers in Enhancing the Bond Strength of Orthodontic Brackets.

Background: The use of lasers in orthodontics has garnered interest for its potential to enhance the bond strength between orthodontic brackets and tooth surfaces, a crucial factor for successful orthodontic treatment. This study aims to investigate the effect of laser irradiation on the bond strength of orthodontic brackets in a sample of 30 patients. Materials and Methods: Thirty patients undergoing orthodontic treatment were divided into two groups. In Group A, brackets were bonded using conventional methods, while in Group B, brackets were bonded after laser irradiation. A diode laser operating at 810 nm was used, with an energy setting of 2.5 W for 20 s. After bonding, a universal testing machine measured the bond strength in megapascals (MPa). The adhesive remnant index (ARI) was also recorded to determine the mode of bond failure. Statistical analyses were conducted to compare the results between the groups. Results: The mean bond strength in Group B (laser irradiation) was significantly higher (P < 0.05) than in Group A (conventional bonding). Group B exhibited a mean bond strength of 9.72 MPa, whereas Group A showed a mean bond strength of 7.41 MPa. The ARI scores indicated that Group B had more adhesive remaining on the tooth surface, suggesting a stronger bond. Conclusion: Laser irradiation prior to orthodontic bracket bonding resulted in significantly enhanced bond strength compared to conventional bonding methods. The increased bond strength and greater adhesive remnant on the tooth surface indicate that laser irradiation improves the adhesion between brackets and tooth enamel. Integrating lasers into orthodontic procedures has the potential to elevate treatment outcomes by ensuring durable bracket adhesion.

Effects of the conventional, soft start, and pulse delay modes produced by light-emitting diode device on microleakage beneath metal brackets: An in vitro comparative study.

BACKGROUND: This study aimed to evaluate microleakage beneath metal brackets cured by different light curing modes. MATERIALS AND METHODS: Sixty extracted human premolars were randomly divided into three groups according to the light curing mode. Metal brackets were bonded in all groups according to the manufacturer's recommendations with a light-emitting diode device. Light curing was applied as follows: group 1: conventional mode (10 s mesial+10 s distal); group 2: soft start mode (15 s mesial+15 s distal); group 3: pulse delay mode (3 s mesial+3 s distal, followed by 3min of no photoactivation, then 9 s mesial+9 s distal). Radiant exposure was the same in all study groups. After curing, the teeth were incubated at 37 degrees for 24hours, then thermocycled 500 times. Next, they were sealed with nail varnish, immersed in methylene blue 1% for 24hours, sectioned, and examined under a stereomicroscope. Microleakage was measured at both enamel-adhesive and bracket-adhesive interfaces, and the total microleakage for each tooth was computed. Statistical analyses were performed using Kruskal-Wallis and Welch test for comparing microleakage among groups. Wilcoxon signed ranks test was used for comparing microleakage between the bracket-adhesive and enamel-adhesive interfaces. RESULTS: There was no significant difference in microleakage at the bracket-adhesive interface among study groups. At the enamel-adhesive interface and total microleakage, the pulse delay group exhibited significantly lower microleakage than the conventional group. Whereas there was no significant difference between the soft start group and other study groups. In all study groups, microleakage at the enamel-adhesive interface was greater than that at the bracket-adhesive interface. CONCLUSION: The pulse delay mode caused lesser microleakage than the conventional mode. This supports the use of this mode in orthodontic bonding.

Survival rate of indirectly bonded brackets using single vs. two-component orthodontic adhesive: A 12-month split-mouth clinical trial.

Objective: Compare the bonding survival rate of two distinct bonding materials: Ortho Solo + Gradia LoFlo Resin and single component GC Ortho Connect. Materials and Methods: Indirect bonding fixed appliance treatment was required for 26 consecutive patients, 8 males and 18 females, with a mean age of 22.1 +/- 4.2 years. All patients were treated with SWM (Straight-Wire Mirabella) technique (Sweden and Martina, Due Carrare, Padova, Italy). Each patient's bonding process followed a contralateral pattern. Firstly, a 37 % orthophosphoric acid etching gel was used for 20 s, subsequently the single or two components light-cured adhesives were applied through a split-mouth cross-arch procedure. The patients underwent a 12-month follow-up period and brackets failures were rebounded, but not further included in the study. Statistical analysis was performed to analyse the survival rate of the bonding materials and the influence of the variables, with a significant level of α = 0,05. Results: The GC Connect group was used on 349 teeth, while the Ortho Solo + Gradia group was used on 351 teeth, and the indirect debonding rate was respectively 17.5% and 12.8%. With respect to the total sample, statistically significant values were found for both sex and dental arch. The bracket's survival rate for incisors, canines, premolars and molars was not significant. However, a higher debonding rate was clinically appreciable in upper and lower molars. Conclusion: In a 12-months observation period, considering all maxillary and mandibular teeth the indirect survival rate for the group GC Ortho Connect and Ortho Solo + Gradia was respectively 82.5% and 87.2%. Although the difference was not significant, a pronounced tendency to debonding for the single component group was appreciable from a clinically point of view.

Effects of the conventional, soft start, and pulse delay modes produced by light-emitting diode device on metal brackets bond strength and enamel damage: An in vitro comparative study.

OBJECTIVES: This study aimed to compare the bond strength and enamel damage following debonding of metal brackets cured by different light-curing modes: conventional, soft start, and pulse delay modes. MATERIAL AND METHODS: Sixty extracted upper premolars were randomly divided into three groups according to the used light-curing mode. Metal brackets were bonded with a light-emitting diode device employing different modes. Group 1: conventional mode (10s mesial+10 s distal); group 2: soft start mode (15s mesial+15s distal); group 3: pulse delay mode (3s mesial+3s distal, followed by 3min of no photoactivation, then 9s mesial+9s distal). Radiant exposure was the same in all study groups. Shear bond strengths of the brackets were tested with a universal testing machine. A stereomicroscope was used to determine the number and length of enamel microcracks. One-Way ANOVA and Kruskal-Wallis tests were used to detect significant differences in shear bond strength and microcracks number and length among groups. RESULTS: The soft start and pulse delay modes produced significantly greater shear bond strength than the conventional mode (19.46±4.90MPa; 20.47±4.97MPa; 12.14±3.79MPa, respectively, P<0.001). However, there was no significant difference between the soft start and pulse delay groups (P=0.768). The number and length of microcracks increased significantly after debonding in all study groups. The change in microcracks length was not different among study groups. CONCLUSION: The soft start and pulse delay modes produced greater bond strength than the conventional mode without predisposing enamel to higher risk of damage. Conservative methods for debonding are still required.

Clinical performance of light-cured orthodontic adhesives for bonding brackets - an in-vitro study.

Background: The dental profession is seeing a constant influx of new adhesive systems from manufacturers, each claiming to be more dependable than the last. This study assessed the bond strength and adhesive remnants of different light-cured adhesives used for bonding metal brackets to teeth. Methods: 80 extracted maxillary premolars with the sound crown structure were acid etched and bonded with brackets on their buccal surfaces utilizing primer and light-cured adhesives into four equal groups, which are Transbond XT, Heliosit, Enlight, and Bracepaste. Shear bond strength (SBS) for de-bonding the brackets were evaluated with Instron- testing machine after 48 hours. The de-bonded samples' adhesive remnant index (ARI) scores were also measured. Results: The maximum mean SBS was found for Transbond XT (12.91 ± 2.0 MPa), followed by Bracepaste (12.87 ± 1.59 MPa), Enlight (11.77 ± 1.87 MPa), and lowest for Heliosit (10.93 ± 1.71 MPa). According to the four point scale, adhesive remnant index (ARI), Transbond XT has the least adhesive residue left on the tooth, followed by Heliosit. Enlight and Bracepaste have a similar distribution of adhesive, with both having a maximum amount left. Conclusion: It can be inferred that all groups involved demonstrated a satisfactory level of bond strength from a clinical perspective. Transbond XT is the preferred orthodontic adhesive over the other three adhesives due to its superior SBS and ARI properties.

Comparison of bracket bond failure with the aerosol-generating and novel non-aerosol-generating bonding techniques during the SARS-CoV-2 pandemic among orthodontic patients: A retrospective cohort study.

BACKGROUND: As per the Centers for Disease Control and Prevention (CDC) guidelines, dentists must avoid the aerosol-generating procedures during the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic. OBJECTIVES: This study aimed to compare the rate of bracket bond failure with the aerosol-generating and non-aerosol generating bonding techniques. MATERIAL AND METHODS: A retrospective cohort study was conducted during the SARS-CoV-2 pandemic on a sample of 44 patients (880 teeth), equally divided into 2 groups: the conventional aerosol-generating bonding technique (ABT); and the novel non-aerosol-generating bonding technique (NABT). The rate of bracket survival and total number of bracket breakages in the 2 groups were assessed by means of the survival regression analysis. The influence of pre-treatment factors, such as the sagittal jaw relationship (ANB), the Frankfort-mandibular plane angle (FMA), overjet, overbite, and upper and lower crowding, on the rate of bracket survival was also evaluated. RESULTS: There was a statistically significant difference between ABT and NABT in terms of bracket survival. The mean bracket survival with ABT was 176.21 ±77.89 days and with NABT it was 162.53 ±83.34 days. The novel technique showed a hazard ratio of bracket survival of 2.99 as compared to the conventional method. There was a statistically significant influence of overjet on the rate of bracket survival (p = 0.010). The posterior segment had a higher rate of bracket failure as compared to the anterior segment in NABT, which was statistically significant (p < 0.001). However, this difference was statistically non-significant in the case of ABT. CONCLUSIONS: There was an increased rate of bracket failure with NABT as compared to ABT. The rate of bracket breakages in the anterior quadrants was comparable for both bonding techniques.

Bracket Transfer Accuracy with the Indirect Bonding Technique-A Systematic Review and Meta-Analysis.

PURPOSE: To investigate the bracket transfer accuracy of the indirect bonding technique (IDB). METHODS: Systematic search of the literature was conducted in PubMed MEDLINE, Web of Science, Embase, and Scopus through November 2021. SELECTION CRITERIA: In vivo and ex vivo studies investigating bracket transfer accuracy by comparing the planned and achieved bracket positions using the IDB technique were considered. Information concerning patients, samples, and applied methodology was collected. Measured mean transfer errors (MTE) for angular and linear directions were extracted. Risk of bias (RoB) in the studies was assessed using a tailored RoB tool. Meta-analysis of ex vivo studies was performed for overall linear and angular bracket transfer accuracy and for subgroup analyses by type of tray, tooth groups, jaw-related, side-related, and by assessment method. RESULTS: A total of 16 studies met the eligibility criteria for this systematic review. The overall linear mean transfer errors (MTE) in mesiodistal, vertical and buccolingual direction were 0.08 mm (95% CI 0.05; 0.10), 0.09 mm (0.06; 0.11), 0.14 mm (0.10; 0.17), respectively. The overall angular mean transfer errors (MTE) regarding angulation, rotation, torque were 1.13° (0.75; 1.52), 0.93° (0.49; 1.37), and 1.11° (0.68; 1.53), respectively. Silicone trays showed the highest accuracy, followed by vacuum-formed trays and 3D printed trays. Subgroup analyses between tooth groups, right and left sides, and upper and lower jaw showed minor differences. CONCLUSIONS AND IMPLICATIONS: The overall accuracy of the indirect bonding technique can be considered clinically acceptable. Future studies should address the validation of the accuracy assessment methods used.

Siloranes-Suitability of a Novel Adhesive for Orthodontic Bracket Bonding.

Recently, an epoxy-based resin-Filtek Silorane-has been proposed for restorative fillings. It was the aim of the investigation to evaluate the suitability of this novel resin for orthodontic bracket bonding on unground enamel. Shear bond strength was measured for two adhesives-Filtek Silorane, Transbond XT-in combination with steel, ceramic and polymer brackets. For Filtek Silorane etching was performed with the Silorane self-etching primer, as well as phosphoric acid. The Transbond XT samples were etched with phosphoric acid only and served as the control group. All samples were thermo-cycled (1000×, 5-55 °C). Shear testing was carried out with an Instron 3344. In addition, ARI scores were evaluated. The Shear bond strength showed a weak adhesion of Filtek Silorane to unprepared enamel, either with the self-etching primer or the conventional etching (0.87-4.28 MPa). The Shear bond strength of the control group was significantly higher (7.6-16.5 MPa). The ARI scores showed a clear failure at the enamel-adhesive interface for all Filtek Silorane samples. For the combination of Transbond XT and different brackets the failure was found at the adhesive-bracket interface. The novel epoxy-based resin Filtek Silorane is not appropriate for bracket bonding to unprepared enamel.

Orthodontic Bracket Bonding Using Self-adhesive Cement to Facilitate Bracket Debonding.

PURPOSE: To evaluate shear bond strength (SBS), adhesive remnant index (ARI), and orthodontic bracket base after debonding of orthodontic brackets bonded using two different adhesives. MATERIALS AND METHODS: Ninety sound human premolars were divided into three groups of n = 30. 1. Transbond, where brackets were bonded with Transbond XT (3M Unitek); 2. Multilink, where brackets were bonded with Multilink Speed (Ivoclar Vivadent); 3. Multilink+etch, where brackets were bonded using Multilink Speed after etching enamel. ARI scores were obtained using a stereomicroscope. SEM was used to evaluate the treated enamel surfaces and the base of the brackets. One-way ANOVA was performed to statistically analyze SBS. The Kruskal-Wallis test was conducted to investigate ARI scores, followed by multiple comparison tests (p < 0.05). RESULTS: SBS was significantly lower in the Multilink group compared to the other groups (p < 0.05). SEM evaluation revealed minimum penetration of resin tags within the enamel and that most of the resin was attached to the base of the brackets in the Multilink group compared to the other two groups (p < 0.05). CONCLUSION: Application of Multilink Speed on nonetched enamel provides acceptable SBS of orthodontic brackets bonded to enamel with minimum penetration of resin tags into enamel and less residual resin on tooth surfaces.

Comparison of the accuracy of two techniques for three-dimensional digital indirect bonding of orthodontic brackets: A randomized controlled trial

ABSTRACT Objective: This study aimed to clinically compare the accuracy of bracket positioning between three-dimensionally (3D) printed indirect bonding trays and vacuum-formed trays made over 3D-printed models. Material and Methods: Fourteen patients, planned for fixed orthodontic therapy, were randomly divided into two equal groups. For both groups, both dental arches were scanned, to acquire virtual models, brackets were virtually positioned from central incisors to second premolars, and scans for the final bracket positions were performed. In the first group, transfer trays were 3D-printed. In the second group, virtual models were 3D-printed, and vacuum-formed soft sheets were thermoformed on the printed model. Teeth were indirectly bonded and then scanned. Superimposition of the virtual and the final bracket positioning scans was performed to measure linear and angular deviations in brackets positions. Results: The first group showed significantly less occlusogingival and buccolingual linear errors than the second group. No significant differences in angular deviations were found between both groups. The frequencies of clinically acceptable linear errors within 0.5 mm and angular errors within 2° showed no statistically significant difference between both groups (p> 0.05 for all measurements). The transfer errors in both groups showed linear directional biases toward the mesial, gingival and labial directions. There was no statistically significant difference in the rate of immediate debonding between both groups (10.7% and 7.1% for the first and the second groups, respectively, p=0.295). Conclusions: 3D-printed indirect bonding trays were more accurate than vacuum-formed trays, in terms of linear deviations. Both types of trays showed similar angular control.

RESUMO Objetivo: Esse estudo teve como objetivo comparar clinicamente a precisão no posicionamento de braquetes usando guias de colagem indireta impressas tridimensionalmente (3D) e guias termoformadas a vácuo em cima de modelos impressos em 3D. Material e Métodos: Quatorze pacientes, planejados para tratamento ortodôntico fixo, foram divididos aleatoriamente em dois grupos de igual tamanho. Em ambos os grupos, as duas arcadas dentárias foram escaneadas para a criação dos modelos virtuais, os braquetes foram posicionados virtualmente dos incisivos centrais aos segundos pré-molares, e foram feitos os escaneamentos das posições finais dos braquetes. No primeiro grupo, as guias de transferência foram impressas em 3D. No segundo grupo, os modelos virtuais foram impressos em 3D e as guias foram termoformadas a vácuo em cima dos modelos impressos. Os braquetes foram colados de forma indireta e depois feitos os escaneamentos. Uma sobreposição das posições planejadas virtualmente e do escaneamento com os braquetes na posição final foi realizada para medir os desvios lineares e angulares nas posições dos braquetes. Resultados: O primeiro grupo apresentou significativamente menos erros lineares oclusogengivais e vestibulolinguais do que o segundo grupo. Não foram encontradas diferenças significativas nos desvios angulares entre os dois grupos. As frequências de erros lineares clinicamente aceitáveis menores que 0,5 mm e de erros angulares menores que 2° não apresentaram diferença estatisticamente significativa entre os dois grupos (p > 0,05 para todas as medições). Os erros de transferência em ambos os grupos mostraram tendências a desvios lineares nas direções mesial, gengival e labial. Não houve diferença estatisticamente significativa entre os dois grupos para a taxa de descolagem imediata (10,7% e 7,1% para o primeiro e o segundo grupos, respectivamente, p=0,295). Conclusões: As guias de colagem indireta impressas em 3D foram mais precisas em termos de desvios lineares do que as guias termoformadas a vácuo. Os dois tipos de guias apresentaram controle angular semelhante.

Tooth color change due to different etching and debonding procedures.

OBJECTIVES:: To compare the effects of different etching techniques, 12-, 24-bladed tungsten carbide burs, and polishing discs on tooth color changes during orthodontic treatment. MATERIALS AND METHODS:: 59 individuals (mean age: 15.20 ± 1.59 years) were divided into four groups: 37% phosphoric acid and adhesive primer was used in Groups I and II whereas self-etch primer was used in Groups III and IV for enamel preparation. After orthodontic treatment, residual adhesives were cleaned with 12-bladed tungsten carbide burs in Groups I and III, while 24-bladed tungsten carbide burs were used in Groups II and IV. All teeth were polished with medium and fine Sof-Lex XT discs (3M ESPE, St Paul, Minnesota). Color measurements were taken from upper incisors and canines at pretreatment (T0), after cleaning with tungsten carbide burs (T1) and polishing with discs (T2). Wilcoxon test was used for evaluation of L*, a*, b* changes and Kruskal-Wallis for intergroup comparison of color changes. RESULTS:: L*, a*, b* values, except a* at Groups I, II, IV, and b* at Group III, changed significantly ( P < .05). Groups III and IV showed significantly different color alterations from T0 to T1 ( P < .05). After polishing, tooth color alterations were not significantly different among the groups. CONCLUSIONS:: In self-etch bonding groups, a 12-bladed tungsten carbide bur caused less color change than the 24-bladed tungsten carbide bur. Orthodontic treatment resulted with visible and clinically unacceptable tooth color alterations regardless of the enamel preparation and clean-up techniques. Polishing reduced the effect of tungsten carbide burs, but did not affect the total influence of orthodontic treatment on the tooth color.

In vitro evaluation of microleakage under orthodontic brackets bonded with different adhesive systems.

OBJECTIVE: Adhesives systems have a drawback when utilized for bonding orthodontic brackets: they shrink during photopolymerization creating microleakage. The aim of this study was to assess the stability of different orthodontic adhesives around brackets and enamel. MATERIALS AND METHODS: Sixty noncarious mandibular premolars extracted for orthodontic reasons were randomly divided into six groups of adhesives used for bonding brackets to dental enamel: NeoBond® Light Cure Adhesive Kit, Transbond™ Plus Self-Etching, Victory V-Slot APC PLUS® + Transbond™ MIP, Rely-A-Bond® Kit, Light Cure Orthodontic Adhesive Kit (OptiBond®), and Transbond™ MIP. Following bonding, all teeth underwent 2500 cycles of thermal cycling in baths ranging from 5°C to 55°C before being immersed in 2% methylene blue for 24 h. All samples were examined under a binocular microscope to assess the degree of microleakage at the "bracket-adhesive" and "adhesive-enamel" interfaces in the gingival and occlusal regions of the bracket. RESULTS: A significant difference was found at the "occlusal bracket-adhesive" interface. The highest microleakage values were found in the occlusal region, although no significant. Microleakage was observed in all groups. CONCLUSION: Group 2 had the highest microleakage values whereas Group 6 had the lowest values.

Effects of two erbium-doped yttrium aluminum garnet lasers and conventional treatments as composite surface abrasives on the shear bond strength of metal brackets bonded to composite resins.

BACKGROUND: Bonding brackets to dental surfaces restored with composites are increasing. No studies to date have assessed the efficacy of laser irradiation in roughening of composite and the resulted shear bond strength (SBS) of the bonded bracket. We assessed, for the 1(st) time, the efficacy of two laser beams compared with conventional methods. MATERIALS AND METHODS: Sixty-five discs of light-cured composite resin were stored in deionized distilled water for 7 days. They were divided into five groups of 12 plus a group of five for scanning electron microscopy (SEM): Bur-abrasion followed by phosphoric acid etching (bur-PA), hydrofluoric acid conditioning (HF), sandblasting, 3 W and 2 W erbium-doped yttrium aluminum garnet laser irradiation for 12 s. After bracket bonding, specimens were water-stored (24 h) and thermocycled (500 cycles), respectively. SBS was tested at 0.5 mm/min crosshead speed. The adhesive remnant index (ARI) was scored under ×10 magnification. SEM was carried out as well. Data were analyzed using analysis of variance (ANOVA), Kruskal-Wallis, Tukey, Dunn, one-sample t-test/Wilcoxon tests, and Weibull analysis (α =0.05). RESULTS: The SBS values (megapascal) were bur-PA (11.07 ± 1.95), HF (19.70 ± 1.91), sandblasting (7.75 ± 1.10), laser 2 W (15.38 ± 1.38), and laser 3 W (20.74 ± 1.73) (compared to SBS = 6, all P = 0.000). These differed significantly (ANOVA P = 0.000) except HF versus 3 W laser (Tukey P > 0.05). ARI scores differed significantly (Kruskal-Wallis P = 0.000), with sandblasting and 2 W lasers having scores inclined to the higher end (safest debonding). Weibull analysis implied successful clinical outcome for all groups, except for sandblasting with borderline results. CONCLUSION: Considering its high efficacy and the lack of adverse effects bound with other methods, the 3 W laser irradiation is recommended for clinical usage.

BPA qualtitative and quantitative assessment associated with orthodontic bonding in vivo.

OBJECTIVE: To assess the in vivo amount of BPA released from a visible light-cured orthodontic adhesive, immediately after bracket bonding. METHODS: 20 orthodontic patients were recruited after obtaining informed consent. All patients received 24 orthodontic brackets in both dental arches. In Group A (11 patients), 25 ml of tap water were used for mouth rinsing, whereas in Group B (9 patients) a simulated mouth rinse formulation was used: a mixture of 20 ml de-ionized water plus 5 ml absolute ethanol. Rinsing solutions were collected before, immediately after placing the orthodontic appliances and after washing out the oral cavity and were then stored in glass tubes. Rinsing was performed in a single phase for 60s with the entire volume of each liquid. The BPA analysis was performed by gas chromatography-mass spectrometry. RESULTS: An increase in BPA concentration immediately after the 1st post-bonding rinse was observed, for both rinsing media, which was reduced after the 2nd post-bonding rinse. Water exhibited higher levels of BPA concentration than water/ethanol after 1st and 2nd post-bonding rinses. Two-way mixed Repeated Measures ANOVA showed that the primary null hypothesis declaring mean BPA concentration to be equal across rinsing medium and rinsing status was rejected (p-value <0.001). The main effects of the rinsing medium and status, as well as their interaction were found to be statistically significant (p-values 0.048, <0.001 and 0.011 respectively). SIGNIFICANCE: A significant pattern of increase of BPA concentration, followed by a decrease that reached the initial values was observed. The amount of BPA was relatively low and far below the reference limits of tolerable daily intake.

Resin bonding of metal brackets to glazed zirconia with a porcelain primer.

OBJECTIVE: The aims of this study were to compare the shear bond strength between orthodontic metal brackets and glazed zirconia using different types of primer before applying resin cement and to determine which primer was more effective. METHODS: Zirconia blocks were milled and embedded in acrylic resin and randomly assigned to one of four groups: nonglazed zirconia with sandblasting and zirconia primer (NZ); glazed zirconia with sandblasting, etching, and zirconia primer (GZ); glazed zirconia with sandblasting, etching, and porcelain primer (GP); and glazed zirconia with sandblasting, etching, zirconia primer, and porcelain primer (GZP). A stainless steel metal bracket was bonded to each target surface with resin cement, and all specimens underwent thermal cycling. The shear bond strength of the specimens was measured by a universal testing machine. A scanning electron microscope, three-dimensional optical surface-profiler, and stereoscopic microscope were used to image the zirconia surfaces. The data were analyzed with one-way analyses of variance and the Fisher exact test. RESULTS: Group GZ showed significantly lower shear bond strength than did the other groups. No statistically significant differences were found among groups NZ, GP, and GZP. All specimens in group GZ showed adhesive failure between the zirconia and resin cement. In groups NZ and GP, bonding failed at the interface between the resin cement and bracket base or showed complex adhesive and cohesive failure. CONCLUSIONS: Porcelain primer is the more appropriate choice for bonding a metal bracket to the surface of a full-contour glazed zirconia crown with resin cement.

Measurement and comparison of bracket transfer accuracy of five indirect bonding techniques.

OBJECTIVE: To measure and compare bracket transfer accuracy of five indirect bonding (IDB) techniques. MATERIALS AND METHODS: Five IDB techniques were studied: double polyvinyl siloxane (double-PVS), double vacuum-form (double-VF), polyvinyl siloxane vacuum-form (PVS-VF), polyvinyl siloxane putty (PVS-putty), and single vacuum-form (single-VF). Brackets were bonded on 25 identical stone working models. IDB trays were fabricated over working models (n  =  5 per technique) to transfer brackets to another 25 identical stone patient models. The mesiodistal (M-D), occlusogingival (O-G), and faciolingual (F-L) positions of each bracket were measured on the working and patient models using digital photography (M-D, O-G) and calipers (F-L). Paired t-tests were used to compare bracket positions between working and patient models, and analysis of variance was used to compare bracket transfer accuracy among the five techniques. RESULTS: Between the working and patient models, double-VF had the most teeth with significant differences (n  =  6) and PVS-VF the fewest (n  =  1; P < .05). With one exception, all significant differences were ≤0.26 mm and most (65%) were ≤0.13 mm. When the techniques were compared, bracket transfer accuracy was similar for double-PVS, PVS-putty, and PVS-VF, whereas double-VF and single-VF showed significantly less accuracy in the O-G direction. CONCLUSIONS: Although overall differences in bracket position were relatively small, silicone-based trays had consistently high accuracy in transferring brackets, whereas methods that exclusively used vacuum-formed trays were less consistent.

Evaluation of the anti-cariogenic potential and bond strength to enamel of different fluoridated materials used for bracket bonding / Avaliação do potencial anti-cariogênico e da resistência adesiva ao esmalte de diferentes materiais contendo fluoreto, utilizados para colagem de braquetes

Objective: To evaluate the in vitro and in situ anti-cariogenic potential and bond strength to enamel of materials containing fluoride (F), used for bracket bonding: Transbond XT (GT, negative control), Transbond Plus Color Change (GTF), Transbond-Self-Etching Primer (GSAF) and Vitremer (GV, positive control). Material and method: In the in vitro study, the specimens were premolars with bonded brackets (n=12/group). After pH cycling, the F release, bond strength, fracture mode and presence of white spot lesions were assessed. In the in situ study, the specimens were enamel fragments with bonded brackets (n=12/group). Twelve volunteers wore palatal appliances in 4 phases, with cariogenic challenge. Bond strength, fracture mode and change in surface hardness (%SH) were determined. Result: Relative to the in vitro study, F release (ppm) was: GT=0.257±0.068c; GTF=0.634±0.100b; GSAF=0.630±0.067b; GV=2.796±1.414a. Only GV showed no white spot lesions. Bond strength values (MPa) were GT=7.62±7.18a; GTF=5.15±6.91ab; GSAF=3.42±2.97bc; GV=2.87±2.09c. Adhesive fracture was the most frequent type, except for GTF. In the in situ study, %SH was: GT=-56.0±18.3a; GTF=-57.6±11.9a; GSAF=-57.1±11.3a; GV=-52.4±25.8a. Bond strength values were GT=9.5±4.4a; GTF=11.1±5.9a; GSAF=13.2± 6.6a; GV=6.6±4.0a. Cohesive fracture in material was the most frequent type, except for GTF. Conclusion: Vitremer (GV) showed the highest anti-cariogenic potential in the in vitro study. However, it was not confirmed by the in situ study. Regarding bond strength values from the in situ study, all materials were shown to be adequate for clinical practice.

Objetivo: Avaliar in vitro e in situ o potencial anti-cariogênico e a resistência adesiva ao esmalte de materiais contendo fluoreto utilizados para a colagem de braquetes: Transbond XT (GT, controle negativo), Transbond Plus Color Change (GTF), Transbond Self Etching Primer (GSAF) and Vitremer (GV, controle positivo). Material e método: No estudo in vitro, as unidades experimentais foram premolares com braquetes colados (n = 12/grupo). Após ciclagem de pH, a liberação de F, resistência adesiva, modo de fratura e presença de mancha branca foram avaliados. No estudo in situ, as unidades experimentais foram fragmentos de esmalte com braquetes colados (n = 12/grupo). Os doze voluntários utilizaram dispositivos palatinos em 4 fases, com desafio cariogênico. Resistência adesiva, modo de fratura e variação de dureza superficial (%SH) foram determinados. Resultado: No estudo in vitro, a libertação de F (ppm) foi: GT=0,257±0,068c; GTF=0,634±0,100b; GSAF=0,630±0,067b; GV=2,796±1,414a. Apenas GV não apresentou lesões de mancha branca. Os valores de resistência de união (MPa) foram GT=7,62±7,18a; GTF=5,15±6,91ab; GSAF=3,42±2,97bc; GV=2,87±2,09c. A fratura adesiva foi mais frequente, com exceção de GTF. Para o estudo in situ, % SH foi: GT=-56,0±18,3a; GTF=-57,6±11,9a; GSAF=-57,1±11,3a; GV=-52,4±25,8a. Os valores de resistência de união foram GT=9,5±4,4a; GTF=11,1±5,9a; GSAF=13,2±6,6a; GV=6,6±4,0a. Fratura coesiva no material foi a mais frequente, exceto para GTF. Conclusão: Vitremer (GV) apresentou maior potencial anti-cariogênico no estudo in vitro, mas isso não se confirmou no estudo in situ. Os valores de resistência de união, a partir do estudo in situ, demonstraram que eles são adequados para a prática clínica.