A study to investigate the bond strengths of orthodontic brackets bonded to prosthetic acrylic teeth

3D-Printed One-piece Versus Two-piece Orthodontic Clear Aligner Attachments Bonded with Provisional Crowns: A Proof of Concept

OBJECTIVES

This study aimed to introduce a novel technique for fabricating provisional crowns integrated as a single unit with aligner attachments.

METHODS

A total of 60 crowns with attachments were prepared: 20 conventional (Protemp) and 40 3D-printed (20 bonded with attachments; 20 integrated with composite attachments as a single unit) using NextDent resin. Two central incisors were scanned (once without attachments and once with attachments) to create STL files for specimen printing. Half of the specimens (30, n=10 per group) underwent thermal cycling (5000 cycles). Shear bond strengths (MPa) were evaluated using a universal testing machine. The debonded areas and attachment failures were analyzed to determine the fracture type. Data analyses were performed using ANOVA and post hoc Tukey tests (α = .05).

RESULTS

The 3D-printed specimens showed higher strength values than the bonded attachments per group (P <0.001). The 3D-printed crowns with attachments demonstrated the highest strength (12.39±1.92 MPa). Thermal cycling significantly decreased the bond strength of the attachments (P <0.001), except in the 3D-printed crowns with composite attachments as a single unit, which showed no significant change after thermal cycling (P=0.643). In the bonded attachment groups, the adhesive type was the predominant failure mode, while in the 3D-printed groups, attachment fractures were the primary cause of failure.

CONCLUSION

The 3D-printed provisional crowns with attachments have high strength and is clinically appropriate for orthodontic treatment when temporization of teeth is indicated.

CLINICAL SIGNIFICANCE

The developed technique for fabricating 3D-printed provisional restorations with orthodontics attachments as a single unit is a promising approach. The technique may be incorporated into the digital orthodontic treatment workflow when temporization is indicated.

The effect of surface treatment and thermal aging on the bonding of clear aligner attachments to provisional resin-based material: shear bond strength analysis

Objectives

The aim of this study is to evaluate the effect of different surface treatments on the shear bond strength (SBS) of clear aligner attachments bonded to Bis-acryl provisional crowns.

Methods

120 cylindrical bisacrylic composite material (ProTemp type) specimens were prepared and divided into six groups (n = 20) based on surface treatment, control: (no treatment); super coarse grit diamond bur, carbide bur, alumina-blasting, non-thermal plasma treatment, and Er:YAG laser treatment. The features of treated surfaces were examined using scanning electron microscopy (SEM). A flowable composite resin (Transbond XT; 3M Unitek) was bonded to the specimens forming the attachment. Half of specimens were subjected to thermal cycling (5,000 cycles). SBS was measured before and after thermal cycling. Each specimen was loaded at the attachment/resin interface at a speed of 0.5 mm/min until failure. The nature of the failure was analyzed using the composite remnants index (CRI). Two-way ANOVA and Tukey HSD were used for data analysis α =  0.5. For CRI scores analysis, Kruskal-Wallis test and Dunn's multiple comparison were used as post-hoc test.

Results

SEM analysis showed that all surface treatments altered surface properties and increase surface bonding area. The specimens treated with plasma, Er:YAG laser, and alumina-blasting had higher SBS values before and after thermal cycling. In comparison to control plasma, Er:YAG laser, and alumina-blasting showed a significant increase in SBS (P < 0.001) while carbide and diamond bur groups showed no significant differences (P > 0.05). Thermal cycling significantly decreased the SBS of control, carbide bur, diamond bur, and Er:YAG laser while no significant effect of alumina-blasting and plasma group. Er:YAG laser and plasma groups significantly exhibited more dominance for scores 2 and score 3 and the absence of score 0.

Conclusion

Alumina-blasting, Er:YAG laser, or non-thermal plasma surface treatments increased the shear bond strength between clear aligner attachments and resin-based restorations.

Bond Strength of Orthodontic Brackets to Temporary Crowns: In vitro Effects of Surface Treatment

Background

To evaluate bond strength of orthodontic brackets to temporary crowns.

Materials and Methods

A bis-acrylic composite was used to create a total of 25 discs, which were then divided into five groups based on how their surfaces were treated with black, blue, green, and sandblasted diamond burs, in addition to a control group. Software called SPSS was used to analyze the outcome.

Results

The average pressures measured for the green bur, black bur, and sandblasting, respectively, were 12.05 MPa, 12.87 MPa, and 19.25 MPa. Comparing the control and blue groups, a substantial variation in shear bond strength was only noticed with reference to sandblasting.

Conclusion

The binding strength of orthodontic brackets is increased by sandblasting temporary crowns.

Effect of Different Surface Treatments on the Shear Bond Strength of Metal Orthodontic Brackets Bonded to CAD/CAM Provisional Crowns

BACKGROUND

The aim of this study was to find the best surface treatment for CAD/CAM provisional crowns allowing the optimal bond strength of metal brackets.

METHODS

The sample consists of 30 lower bicuspids and 180 provisional crowns. The provisional crowns were randomly divided into six different groups. Orthophosphoric acid etching (37%) was applied to 30 lower bicuspids. The provisional crowns had undergone different surface treatments. Group 1: No treatment (Control Group). Group 2: Diamond bur. Group 3: Sandblasting. Group 4: Plastic Conditioner. Group 5: Diamond bur and Plastic Conditioner. Group 6: Sandblasting and Plastic Conditioner. The brackets in all groups were identically placed using Transbond XT^® Primer and Transbond XT^® Paste. Then, the entire sample underwent an artificial aging procedure, and a measurement of the bond strength was conducted. After debonding, the surface of the crowns was examined to determine the quantity of the adhesive remnant.

RESULTS

Bonding to natural crowns recorded the highest average, followed by the averages of groups 5 and 6. However, group 1 recorded the lowest average. Groups 2 and 4 had very close averages, as well as groups 5 and 6. A statistically significant difference between the averages of all groups was recorded (p < 0.001) except for groups 2 and 4 (p = 0.965) on the one hand, and groups 5 and 6 (p = 0.941) on the other hand.

DISCUSSION

The bonding of brackets on provisional crowns is considered a delicate clinical procedure. In fact, unlike natural crowns, the orthophosphoric acid usually used does not have any effect on the surface of provisional crowns.

CONCLUSIONS

Using a diamond bur combined with the plastic conditioner and sandblasting combined with that same product resulted in a bond strength close to natural crown.

Bond Strength of Orthodontic Brackets to Temporary Crowns: In Vitro Effects of Surface Treatment

Background

The number of patients seeking orthodontic treatment has been consistently increasing. During orthodontic treatment, it is recommended to place the provisional restoration and to delay the final restoration until completion of orthodontic treatment. Recurrent bracket debonding necessitates orthodontists to prepare the bonding area with special measures.

Objective

This study aimed to evaluate the effect of different grit sizes of diamond burs and sandblasting surface treatment on the shear bond strength of orthodontic brackets to provisional crowns.

Materials and Methods

A total of 75 discs were fabricated from a bisacrylic composite and divided into 5 groups (n = 15) according to surface treatment by black, blue, and green diamond burs and sandblasting in addition to a control group. Metal orthodontic brackets were bonded to discs in a standardized conventional manner. All specimens were subjected to thermocycling with 5000 cycles of alternating 5°C and 55°C waterbaths. The shear bond strength test was performed using a universal testing machine. A scanning electron microscope (SEM) was used to analyze the surface treatment effect and features of debonded surfaces. The amount of composite resin left on the specimen surfaces was analyzed and classified with the adhesive remnant index. One-way ANOVA was performed at α = 0.05.

Results

The shear bond strength of specimens treated with sandblasting was significantly higher than that of the control group under thermal aging conditions (p=0.022), as well as blue burs (p=0.001), while no significant differences were found between different grit diamond burs and the controls (p > 0.05).

Conclusion

Under thermocycling conditions, sandblasting of provisional crowns increases the bond strength of orthodontic brackets.

A Modified Pontic Appliance for Missing Maxillary Incisors

A modified pontic technique is presented that simplifies the management of patients with missing anterior teeth during the course of comprehensive orthodontic care. This technique demonstrates a lingual arch attached to lingual sheaths with the pontic placed on the lingual arch. Information presented includes appliance design, improved bond strength of the bracket on the pontic tooth, preparing the appliance for use as anchorage, and the incorporation of an anterior biteplate in the appliance. A modified pontic appliance improves esthetics and function when treating patients with missing maxillary anterior teeth.

Effect of surface treatment of prefabricated teeth on shear bond strength of orthodontic brackets

Objective:

The aim of this in vitro study was to evaluate and compare the effects of grinding, drilling, sandblasting, and ageing prefabricated teeth (PfT) on the shear bond strength (SBS) of orthodontic brackets, as well as the effects of surface treatments on the adhesive remnant index (ARI).

Methods:

One-hundred-ninety-two PfT were divided into four groups (n = 48): Group 1, no surface treatment was done; Group 2, grinding was performed with a cylindrical diamond bur; Group 3, two drillings were done with a spherical diamond bur; Group 4, sandblasting was performed with 50-µm aluminum oxide. Before the experiment, half of the samples stayed immersed in distilled water at 37^oC for 90 days. Brackets were bonded with Transbond XT and shear strength tests were carried out using a universal testing machine. SBS were compared by surface treatment and by ageing with two-way ANOVA, followed by Tukey’s test. ARI scores were compared between surface treatments with Kruskal-Wallis test followed by Dunn’s test.

Results:

Surface treatments on PfT enhanced SBS of brackets (p< 0.01), result not observed with ageing (p= 0.45). Groups II, III, and IV showed higher SBS and greater ARI than the Group 1 (p< 0.05). SBS was greater in the groups 3 and 4 (drilling, sandblasting) than in the Group 2 (grinding) (p< 0.05). SBS and ARI showed a positive correlation (Spearman’s R²= 0.57; p< 0.05).

Conclusion:

Surface treatment on PfT enhanced SBS of brackets, however ageing did not show any relevance. Sandblasting and drilling showed greater SBS than grinding. There was a positive correlation between SBS and ARI.

Bond strength of stainless steel orthodontic brackets bonded to prefabricated acrylic teeth

OBJECTIVES

The purpose of this in-vitro study was to evaluate the force to debond stainless steel orthodontic brackets bonded to acrylic teeth using different combinations of adhesive and surface treatments.

MATERIALS AND METHODS

One hundred prefabricated upper lateral incisor acrylic teeth were divided into 4 equal groups: Transbond XT® adhesive only (Group 1, control), Transbond XT® adhesive with sandblasting (Group 2), Transbond XT® adhesive with abrasion / + methyl methacrylate (MMA) (Group 3) and Triad® Gel only (Group 4). The force in Newtons (N) to debond the brackets was measured. One-way analysis of variance (ANOVA) and pairwise multi-comparison of means (Šidak's adjustment) were undertaken.

RESULTS

The highest force to debond was recorded for Group 2 (275.7 N; SD 89.0) followed by Group 3 (241.9 N; SD 76.0), Group 1 (142.7 N; SD 36.7) and Group 4 (67.9 N; SD 21.1). Significant differences in bond strength measurements between the experimental groups were detected. Mean force values for the groups revealed no significant differences between Group 2 and Group 3 (p>0.05).

CONCLUSIONS

Both sandblasting and surface abrasion/+ application of methyl methacrylate (MMA) in combination with Transbond XT® adhesive are recommended for bonding stainless orthodontic brackets to acrylic teeth.