In vitro study of bond strength at the resin/brackets interface in first premolars using orthodontics resins and restorative resins

The shear bon strength (SBS) to brackets to the teeth, is necessary strength to resist orthodontic movements, mastication forces induced by food and other forces. The retention mechanism of the bracket base, the preparation of dental and the adhesive material affecting the adhesion between the metal brackets and tooth enamel. Therefore, the purpose of this study is to investigate different systems adhesion; Z100 (3M Unitek, USA), Transbond XT (3M Unitek, USA) and Trulock (RMO, USA) on the shear bond strength of brackets to the enamel. 135 first human premolars, mounted on an acrylic base, were divided into 3 groups of 45 pieces each. They are prepared following the same protocol and a same type of metal brackets bonded, light activated for 40 s, and stored. SBS was performed in an Instron at crosshead speed of 2.0 mm/min. Data were submitted to the Student t test. The Adhesive Remaining Index (ARI) was evaluated. The is no statistical difference between 3 groups. The ARI showed a predominance of scores 2 and 3 for all groups. It is possible conclude that Z100 restoration resin can be used to the adhesion of the orthodontic brackets.

Primer-Treated Ceramic Bracket Increases Shear Bond Strength on Dental Zirconia Surface

The purpose of this study is to evaluate the shear bond strength (SBS) of a primer-treated ceramic bracket on dental zirconia and to compare it with conventional ceramic bracket bonding on surface-treated zirconia. Sintered and finished dental zirconia was sandblasted. Samples were divided according to the treated surfaces: no treatment (X), ceramic primer on zirconia (Z), ceramic primer on bracket base (B), and ceramic primer on both zirconia and bracket base (ZB). The ceramic bracket was bonded on zirconia and SBS was measured before (T0) and after 10,000 cycles of thermocycling (Tf). The failed surfaces were examined under field emission scanning electron microscope (FE-SEM), and adhesive remnant index (ARI) was evaluated. SBS was significantly higher in ZB and significantly lower in X in both T0 and Tf. There was no significant difference between Z and B. In X and B, adhesive failure occurred while ZB showed mixed failures. There was no apparent change in the zirconia surface except for the existence of some adhesive and resin remnants. The application of ceramic primer on the bracket base increased the bonding strength to the level of conventional bonding with fewer adhesive remnants. The highest bonding strength was obtained when the primer-treated bracket was bonded on the primer-treated zirconia.

Relative Assessment of Bonding Strength of Orthodontic Adhesives

Current study was carried for evaluating the shear bond strengths of 3 clinical micro-filled adhesives. The experiments were performed on extracted premolars for orthodontic purpose. The sample size was selected by randomized sampling technique. Sample size was 90 which were divided into three groups. The extracted maxillary first premolars were selected according to inclusion and exclusion criteria. The three adhesives selected for the study were applied to the bracket base according to manufacturer instructions. A Universal Test Machine has been utilized to record the bond shear intensity. The existing remnant adhesive on the teeth has been stereo-microscopically observed and is measured utilizing the Adhesive Remnant Index (ARI).

Effect of Yd:YAG laser irradiation on the shear bond strength of orthodontic metal brackets

ABSTRACT Objective: The purpose of this study was to evaluate the effect of the Yd:YAG laser irradiation on orthodontic bracket base surface. Shear bond strength (SBS) values and sites of the bonding failure interfaces were quantified. Methods: Brackets were divided into two groups: OP (One Piece - integral sandblast base) and OPL (One Piece - laser irradiation). The brackets were randomly bonded on an intact enamel surface of 40 bovine incisors. The SBS tests were carry out using a universal test machine. A stereomicroscopy was used to evaluate the adhesive remnant index (ARI), and surface characterization was performed by scanning electron microscopy (SEM). Student’s t-test was used to compare the SBS between the two groups (p< 0.05). Frequencies and chi-square analysis were applied to evaluate the ARI scores. Results: OPL group showed higher value (p< 0.001) of SBS than OP group (43.95 MPa and 34.81 MPa, respectively). ARI showed significant difference (p< 0.001) between OPL group (ARI 0 = 100%) and OP group (ARI 0 = 15%). SEM showed a higher affinity between the adhesive and the irradiated laser base surface. Conclusions: Yd:YAG laser irradiation on bracket base increased SBS values, showing that bonding failure occurs at the enamel/adhesive interface. Laser-etched bracket base may be used instead of conventional bases in cases where higher adhesion is required, reducing bracket-bonding failure.

Failure mode investigation and re-design of heavy-duty commercial vehicle bogie bracket

Heavy-duty commercial vehicles play a significant role in commodity logistics. For each of these vehicles, the suspension is the most essential system to support the load and road shock. Bogie type suspension system is employed to safeguard the vehicle from road shock. The bogie bracket is a juncture between the chassis and the axle in the suspension system. The bogie bracket has been identified as a critical part of the suspension system. In the present study, bogie bracket base design and modelling was performed using computer-aided engineering (CAE). The strength of the bogie was tested to identify weaker sections. Design modifications were performed to improve the strength on identified critical sections through reinforcement techniques. A road load data acquisition (RLDA) test was conducted under different road conditions to validate CAE results. Five different rough-road road surfaces were chosen for RLDA testing. Using strain gauges, strain data were acquired during the test. Corresponding stress values were obtained and maximum stress was found in all driving conditions. For the base design bogie bracket, under RLDA test, crack initiation and crack propagation were identified under vertical loads. A reinforced bogie bracket was designed and found to have a higher strength and longer expected life than that of the base design.

Evaluation of surface roughness of the bracket slot before and after burning

Slot bracket base is one important element to enable sliding movement of the archwire. Bracket reconditioning by means of burning changes the surface roughness of slot bracket base. The heat above 450 °C shows microstructure changes of the slot surface. On this basis, the present study aims to evaluate surface roughness changes of the slot bracket base before and after reconditioning by means of burning. Sixteen premolar brackets standard edgewise were divided into two groups each consisting of eight brackets. These two groups were tested at three different points using Scanning Electron Microscopy (SEM), with 3000 times of magnification. Subsequentl,group A was burned for 5 seconds (approximately 450 °C) and group B was burned for 10 seconds(approximately 643 °C). After treatment,these two groups were tested for the second time using Scanning Electron Microscopy (SEM), with 3000 times magnification and the images were analyzed using a discrete scale quantitative classification. Afterwards, the data were analyzed using ANOVA (p≤0.05) and post hoc analysis. The result showed that surface roughness of the slot bracket base burned for 10 seconds experienced more significant change than that of bracket burned for 5 seconds and that of the control bracket(p≤0.05).Bracket reconditioning using burning either for 5 to 10 seconds change the surface roughness of the slot bracket base.

Flash-Free Orthodontic Adhesive System Compared with the Conventional Direct Bonding Method

The latest technology in the field of orthodontic materials is represented by the Flash-Free Orthodontic Adhesive System. In the present study this novel technique is compared with the conventional direct bonding method. Ten extracted human premolars were separated into two groups: in the Group 1, APC Flash-Free Adhesive Coated Appliance System (3M Unitek, Monrovia, CA, USA) was bonded, while in the control Group 2, Clarity Advanced braces (3M Unitek, Monrovia, CA, USA) were bonded using XT Adhesive Paste (3M Unitek, Monrovia, CA, USA) applied by the clinician on the bracket base. Bonding times were recorded for each sample. Shear bond strength (SBS) was recorded using Zwick Zoel Z005. After debonding, the adhesive remnant index (ARI) was established for both groups. Group 1 showed a mean bonding time of 21 s, while Group 2 needed about 45 s for each bracket bonding. Both groups had clinically accepted SBS values, but the difference between them was significant (10.97 MPa versus 8.23 MPa). ARI scores were equal to 1 for most samples. In conclusion, reducing the time for bracket placing, APC Flash-Free Coated Appliance System showed a brackets bonding time reduced to half compared to the conventional technique. This aspect, combined with significantly higher SBS values, makes this novel system better than the classical one. For both groups, more than half of the adhesive remained on the bracket base, which facilitates cleaning after debonding.

Shear bond strength and adhesive remnant index of orthodontic brackets bonded to enamel using adhesive systems mixed with TiO2 nanoparticles

ABSTRACT Introduction: It is recently suggested that titanium dioxide (TiO2) nanoparticles can be added to bracket luting agents in order to reduce bacterial activity and protect the enamel. However, it is not known if this addition can affect the shear bond strength (SBS) below clinically acceptable levels. Therefore, this study examined this matter within a comprehensive setup. Methods: This in vitro experimental study was conducted on 120 extracted human premolars randomly divided into four groups (n=30): in groups 1 and 2, Transbond XT light-cured composite with or without TiO2 was applied on bracket base; in groups 3 and 4, Resilience light-cured composite with or without TiO2 was used. Brackets were bonded to teeth. Specimens in each group (n=30) were divided into three subgroups of 10 each; then incubated at 37°C for one day, one month, or three months. The SBS and adhesive remnant index (ARI) were calculated and compared statistically within groups. Results: The SBS was not significantly different at one day, one month or three months (p>0.05) but composites without TiO2 had a significantly higher mean SBS than composites containing TiO2 (p<0.001). The SBS of Transbond XT was significantly higher than that of Resilience (p<0.001). No significant differences were noted in ARI scores based on the type of composite or addition of TiO2 (p>0.05). Conclusions: Addition of TiO2 nanoparticles to Transbond XT decreased its SBS to the level of SBS of Resilience without TiO2; thus, TiO2 nanoparticles may be added to Transbond XT composite for use in the clinical setting.

Injuries and Complications Management with Forsus Appliance

Introduction: Forsus is a useful appliance for non-compliant Class II problems, however various problems can occur when using them.Objective: To demonstrate a comprehensive series of of critical situations that can occur using the Forsus device and to provide the possible solutions of each complication.Materials & Method: The clinical management of the Forsus appliance was analyzed for eighty consecutively treated patients. The Forsus was used five months on average and pictures and clinical record were registered each time a patient had a problem or an injury.Discussion: The most common problem was breakage of the appliance. Breakage could occur as debonding of the lower first premolars or unsoldering of the upper first molar tubes. Lower premolar debonding could be prevented and fixed with an extra layer of flow composite surrounding the bracket base. Lesions of the cheek mucosa were found in several patients. A soft cotton pad used as “wax” was an effective solution to allow soft tissue healing and to prevent spring rubbing against the cheek. Upper molar intrusion occurred mainly when second molars were not included in the upper arch. Some patients experienceddisconnection of the spring and the push rod while opening the mouth wide. They were taught to self-adjust the appliance.Conclusion: The use of the Forsus appliance may lead to relatively frequent problems that the orthodontist can easily preventand manage.