In vitro evaluation of a ceramic bracket with a laser-structured base

Fluorescent Orthodontic Adhesive With APTES-Modified ZnO Quantum Dots: Bond Strength, Cytocompatibility, and Clinical Feasibility

INTRODUCTION

To develop a fluorescent adhesive by incorporating 3-aminopropyltriethoxysilane (APTES)-modified ZnO quantum dots (A-ZnOQDs) and to evaluate its bond strength, rheological properties, cytocompatibility, and removal performance.

METHODS

ZnOQDs were modified with APTES and blended with commercial orthodontic adhesive to construct the fluorescent adhesive, which was divided into four groups (0, 2, 4, and 6 wt.%). Shear bond strength (SBS) was measured with a universal testing machine. Rheological properties were evaluated through a dynamic shear rheometer (DSR) test. Cytocompatibility was assessed with a CCK-8 kit. Bracket bonding and debonding procedures were performed on a head simulator. Adhesive removal effectiveness during bonding and debonding procedures was assessed.

RESULTS

There was no significant difference in SBS among four groups (0%: 10.06 ± 4.81 MPa, 2%: 8.98 ± 3.70 MPa, 4%: 10.88 ± 5.12 MPa, 6%: 8.09 ± 3.43 MPa, p > 0.05). DSR displayed that the rheological curves of group-2% and group-4% were close to that of group-0%. CCK-8 assay indicated cell vitality did not differ among group-0%, group-2%, and group-4% (p > 0.05). Group-4% showed less excess adhesive area (0%: 1.81 ± 1.58 mm2, 4%: 0.95 ± 1.33 mm2, p = 0.0465), less remnant adhesive area (0%: 0.73 ± 0.79 mm2, 4%: 0.07 ± 0.21 mm2, p = 0.0002), more time taken in removing excess adhesive (0%: 40.76 ± 6.44 s, 4%: 47.19 ± 8.40 s, p = 0.0046), and similar time taken in removing remnant adhesive (0%: 40.04 ± 10.05 s, 4%: 43.54 ± 10.18 s, p = 0.2365).

CONCLUSIONS

Fluorescent orthodontic adhesive containing 4 wt.% of A-ZnOQDs with reliable SBS, rheological properties, and cytocompatibility was successfully constructed, with proof that it can be recognised and removed efficiently.

Effect of Different Liquids and Thermal Aging Procedures on the Shear Bond Strength of APC II, APC Flash-Free, and Conventional Ceramic Brackets: An In Vitro Study

Objective

The purpose of this study was to compare the effects of cherry juice, coffee, coke, gastric acid, and the thermo-aging procedure (TAP) on the shear bond strength (SBS) of APC II, APC flash-free, and conventional ceramic brackets.

Methods

A total of 180 human premolar teeth were randomly divided into three major groups according to the type of ceramic bracket. Then, six subgroups (n=10) were established from each major group: Group 1: control; Group 2: only TAP; Group 3: 72 hours of cherry juice exposure + TAP; Group 4: 72 hours of coffee exposure + TAP; Group 5: 72 hours of coke exposure + TAP; and Group 6: 24 hours gastric acid exposure + TAP. SBS was assessed for each specimen using a universal test device, and the adhesive remnant index (ARI) was scored under a light microscope. Kruskal-Wallis and post-hoc Tamhane tests were used to analyze the data.

Results

Among the control groups, the highest SBS value belonged to conventional ceramic brackets (p<0.01). SBS values for all groups decreased as a result of each liquid and TAP. Gastric acid and coke had the greatest detrimental effects on SBS, while TAP had the least negative effects. The SBS values of APC II, APC flash-free, and conventional brackets were found to be statistically insignificant after different liquid exposures and TAP.

Conclusion

TAP and various fluids had a negative impact on the SBS value of ceramic brackets. SBS values, however, were still higher than clinically acceptable (8-9 MPa) values, even after exposure to gastric acid and coke.

Evaluation of stress and displacement of maxillary canine during the single canine retraction in the maxillary first premolar extraction cases- A finite element study

OBJECTIVES

This finite element study aimed to simulate maxillary canine movement during anterior teeth retraction.

MATERIALS AND METHODS

Three methods of maxillary canine movement including miniscrew sliding with high hooks (MSH), miniscrew sliding with low hooks (MSL), and the traditional sliding method (TS) without using miniscrews were simulated using three-dimensional finite element analysis. The initial displacement of the maxillary canine, the maximum principal stress of the periodontal ligament and the Von Mises stress were calculated.

RESULTS

The distolingual tipping movements of the canine were shown in three movement modes. MSH showed a small tendency to lingual tipping movement and a extrusion movement while MSL had the largest lingual inclination. TS demonstrated a tendency toward distolingual torsion displacement. Compressive stress values were mainly concentrated in the range - 0.003 to -0.006 MPa. For tensile stress, the distribution of MSH and MSL was concentrated in the range 0.005 to 0.009 MPa, TS was mainly distributed about 0.003 MPa. Von Mises equivalent stress distribution showed no significant difference.

CONCLUSIONS

The loss of tooth torque was inevitable, irrespective of which method was used to close the extraction space. However, miniscrew application and higher hooks reduced the loss of torque and avoided lingual rotation.

CLINICAL RELEVANCE

This study shows that miniscrew implants with different hooks can better control the movement of the maxillary canines. The non-invasive nature of the finite element analysis and its good simulation of dental stress and instantaneous motion trend have a clinical advantage in the analysis of tooth movement.

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.

Bonding Surface Designs in Fixed Orthodontic Attachments

Fixed orthodontic attachments/appliances work as a medium to transfer the force applied to the teeth. In bonded types, several factors affect the attachment bond strength and their clinical success. The primary approach for increasing the bond strength focused on altering the time and concentration of acid etching; however, the results showed that these changes might increase susceptibility to enamel decalcification. The bonding mechanism of orthodontic attachments may be chemical, mechanical, or a combination of both. Most attachment bonding surfaces (ABSs) have no chemical bond to resin composites. Hence, mechanical retention plays a major role. Developing more bonding surfaces by increasing the macroscopic size of the attachments has esthetic and hygienic limitations, so the ABS design plays a more important role in maintaining and improving the bond strength. In this research, different ABS designs are reviewed and categorized according to manufacturing methods and their features.

The Effect of Brilliant Blue-Based Plaque-Staining Agents on Aesthetic Orthodontic Appliances

Orthodontic appliances discolour over treatment time, and a yellowish plaque builds up on the contact area of the brackets, adhesive and teeth. Brilliant Blue-based plaque-staining agents (BBPSAs), which increase tooth brushing efficiency, have the potential to support the maintenance of proper oral hygiene during orthodontic treatment. However, they exhibit strong colouring properties, and their impact on the aesthetics of braces remains unclear. Therefore, the aim of this study was to investigate the influence of commercially available BBPSAs on the colour of aesthetic orthodontic materials. A light-cured, colour-changing orthodontic adhesive and new-generation, monocrystalline, sapphire brackets were chosen for the experiments. The effect of the staining agent on the tested materials was investigated in terms of the reaction temperature and time, as well as the presence of black tea-induced impurities on the materials. The CIELAB (Commission Internationale de L'éclairage L* a* b*) colour system parameters were measured, and the colour differences (ΔE*ab and ΔE00-the Commission Internationale de L'éclairage 2000 colour-difference) were determined for the materials under several experimental conditions. The braces' green-red colour expression was positively affected by the BBPSA. Under in vitro conditions, the regular use of the BBPSA for 90 days visibly improved the unfavourable colour change caused by the black tea.