Does clinical experience affect the bracket bonding accuracy of guided bonding devices in vitro?

OBJECTIVES

To study whether and how the clinical experience of the operator affects the accuracy of bracket placement using guided bonding devices (GBDs) in vitro.

MATERIALS AND METHODS

Five resin models were bonded virtually with brackets, and the corresponding GBDs were generated and three-dimensionally printed. Nine operators, which included three dental students, three orthodontic students, and three orthodontists, bonded the brackets on the resin models using GBDs on a dental mannequin. After being bonded with brackets, the models were scanned, and the actual and designed positions of the brackets were compared.

RESULTS

There was no immediate debonding. The orthodontists spent a significantly shorter time (22.36 minutes) in bracket bonding than the dental students (24.62 minutes; P < .05). The brackets tended to deviate to the buccal side in the dental student group. Linear deviations tended to be smallest in the orthodontic student group, but no significant difference was found among operators with different clinical experience (P > .5). All linear and angular deviations in each group were under 0.5 mm and 2°, respectively.

CONCLUSIONS

Clinical experience was positively related to the bonding accuracy using GBDs, especially in the buccolingual dimension. Inexperience also led to longer bonding duration. However, bonding accuracy was clinically acceptable in general.

3D printed indirect bonding trays: Transfer accuracy of hard versus soft resin material in a prospective, randomized, single-blinded clinical study

OBJECTIVES

This prospective clinical study aimed to compare transfer accuracy and immediate loss rate of hard versus soft transfer trays utilizing a CAD/CAM workflow.

METHODS

We performed virtual bracket placement on intraoral scans of adolescent patients to create individual indirect bonding trays. Orthodontic software (Appliance Designer, 3Shape, Copenhagen, Denmark) was used to design the trays, which were then produced using 3D printing technology. Patients were randomly assigned to the hard or soft resin groups with a 1:1 allocation. Subgroups were determined based on the Little's Irregularity Index and distributed equally.

RESULTS

552 brackets were bonded onto adolescent patients using 46 CAD/CAM indirect bonding trays. The linear mean transfer errors ranged from -0.011 mm (soft) to -0.162 mm (hard) and angularly -0.255° (hard) and -0.243° (soft). No statistically significant differences were found between the subgroups or soft and hard resin groups. However, the transfer accuracy of molar brackets was significantly lower in the transversal and horizontal directions. All mean transfer errors were within the limits of clinical acceptability. The loss rate was 2.4 % in the hard resin group and 2.3 % in the soft resin group. The Intra Observer Correlation was excellent.

SIGNIFICANCE

CAD/CAM technology for indirect bracket bonding has been proven reliable in a randomized clinical trial. Both hard and soft resin showed a low rate of immediate loss compared to the current literature. Soft resin was more favorable than hard resin in terms of accuracy and usability. However, the indirect bonding of molar brackets is significantly less accurate than incisor brackets.

CAD/CAM indirect bonding trays using hard versus soft resin material: a single-blinded in vitro study

OBJECTIVES

The present in vitro study aimed to evaluate the accuracy of three-dimensional (3D) printed indirect bonding trays consisting of hard or soft resin materials produced using computer-aided design and manufacturing (CAD/CAM).

METHODS

Forty-eight dental casts were 3D printed. Four groups based on frontal crowding were defined and divided into hard- and soft-resin groups. After virtual bracket positioning on the digital models, the transfer trays were 3D printed. To evaluate the accuracy of the procedure, measurements were performed using a digital overlay of the virtual (target) bracket position and a post-bonding scan. The horizontal, transverse, and vertical deviations and angular discrepancies were analyzed. The loss rate was evaluated descriptively as a percentage.

RESULTS

A total of 553 brackets were bonded using 24 soft and 24 resilient indirect bonding trays. The mean deviations were of 0.05 mm (transversal), 0.05 mm (horizontal), 0.09 mm (vertical), 0.13° (angulation) in the resilient resin group and of 0.01 mm (transversal), 0.08 mm (horizontal), 0.08 mm (vertical), 0.37° (angular) in the soft resin group. The loss rate was 6.9% and 0.7% in the hard and soft resin groups, respectively. Angular deviations were significantly higher in the soft resin group (P = 0.009), whereas the loss rate was considerably higher in the hard resin group (P < 0.001).

SIGNIFICANCE

The findings indicate that indirect bonding using CAD/CAM is an accurate procedure in the laboratory setting. Soft resins are considered favorable for loss rate and useability.

Comparison of residual monomer amounts released from indirect bonding adhesives

OBJECTIVES

To quantify the amount of residual monomer released from orthodontic adhesives used in the indirect bonding technique and compare it to a direct bonding composite resin.

MATERIALS AND METHODS

Five hundred stainless steel orthodontic brackets were bonded on bovine incisors using five groups of bonding resins: Transbond XT (TXT), Transbond Supreme LV (SLV), Sondhi Rapid-Set (SRS), Transbond IDB (IDB), and Custom I.Q. (CIQ). Liquid samples were gathered on the first, seventh, 21st, and 35th days. Residual monomer release was measured from the liquid samples with a liquid chromatography device. In addition, the amount and shape of the adhesive between the tooth surface and the bracket base was evaluated using obtained electron microscopy images. The data were analyzed using analysis of variance, and a Tukey post-hoc test was applied.

RESULTS

Hydroxyethylmethacrylate and bisphenol A-glycidyl methacrylate monomers were released by all study groups. Urethane-dimethacrylate was released from the TXT, SLV, IDB, and CIQ groups. Triethylene glycol dimethacrylate was released from TXT, SLV, IDB, and SRS groups. The amount of total monomer release was higher in chemically cured adhesives than in light-cured adhesives. Among the chemically cured adhesives, premix adhesives had the highest amount of total monomer release. The light-cured adhesives had less thickness.

CONCLUSIONS

Light-curing adhesives have significantly less monomer release than chemically polymerized adhesives.

Comparison of bracket bonding between two CAD/CAM guided bonding devices: GBD-U vs GBD-B

OBJECTIVE

To compare the bracket bonding accuracy, efficiency, reproducibility, and three-dimensional (3D) printing duration of the computer-aided design/computer-aided manufacturing (CAD/CAM) unilateral contact guided bonding device (GBD-U) and the bilateral contact guided bonding device (GBD-B) in vitro.

METHODS

Five resin dental model sets were scanned and virtually bonded with brackets. GBD-U and GBD-B were designed and 3D printed for each model. GBD-Us had guide blocks that fit the occlusal sides of the bracket tie-wings, while GBD-Bs had guide arms that fit the occlusal and distal sides of the tie-wings. Five orthodontic residents were recruited to bond brackets on the same 3D-printed copies of resin models in a dental mannequin using GBD-Us and GBD-Bs, respectively. The time for 3D printing of GBDs and bracket bonding was recorded. The linear and angular deviations between the bonded brackets and the virtually bonded ones were measured.

RESULTS

A total of 50 sets of resin models (1000 brackets/tubes) were bonded. The time for 3D printing and bracket bonding was shorter for GBD-Us (41.96 mins/6.38 mins) than for GBD-Bs (78.04 mins/7.20 mins). In both devices, 100% linear deviations and over 95% angular deviations were below 0.5 mm or 2°, respectively. Deviations in the mesiodistal dimension, torque, angulation, and rotation were significantly lower in the GBD-U group (P<0.01). High inter-operator reproducibility of bracket bonding was confirmed for both devices.

CONCLUSION

GBD-U was more time-efficient in 3D printing. Both GBDs showed clinically acceptable accuracy, whereas GBD-U had higher bonding accuracy in the mesiodistal dimension, torque, angulation, and rotation than GBD-B.

CLINICAL SIGNIFICANCE

CAD/CAM GBD-U provides high bracket bonding accuracy in a time-efficient manner and has the potential to be clinically applied.

Transfer Accuracy of Three Indirect Bonding Trays: An In Vitro Study with 3D Scanned Models

Objective

The goal of the current study is to compare the transfer accuracy of two different conventional indirect bonding trays with 3D-printed trays.

Methods

Twenty-two patients' upper dental models were duplicated, scanned and brackets were bonded digitally. Different indirect bonding trays (double vacuum formed, transparent silicone and 3D-printed) were prepared according to three groups. These trays were used for the transfer of the brackets to the patients' models, then models with brackets were scanned. GOM Inspect software was used for the superimposition of virtual bracket setups and models with brackets. A total of 788 brackets and tubes were analyzed. Transfer accuracies were determined according to the clinical limit of 0.5 mm for linear and 2° for angular measurements.

Results

3D-printed trays had significantly lower linear deviation values than other trays for all planes (p<0.05). 3D-printed trays have significantly lower torque and tip deviation values than other groups (p<0.05). Transfer deviations were within the clinically acceptable limit for all transfer trays in horizontal, vertical and transverse planes. Deviation values of the molars were higher than those of the other tooth groups for all trays in the horizontal and vertical planes (p<0.05). Brackets were generally deviated toward the buccal direction in all tray groups.

Conclusion

The transfer accuracy of 3D-printed transfer trays was more successful than the double vacuum formed and transparent silicone trays in the indirect bonding technique procedure. Deviations in the molar group were greater than those in the other tooth groups for all transfer trays.

Impact of different pretreatments and attachment materials on shear bond strength of indirectly bonded brackets using CAD/CAM transfer trays to monolithic zirconia

OBJECTIVE

Investigating the impact of different pretreatment methods, attachment materials and aging regimens on shear bond strength (SBS) between zirconia and indirectly bonded brackets using CAD/CAM transfer trays.

METHODS

Zirconia substrates were conditioned with silica coated alumina (CoJet) and a) Clearfil Ceramic Primer Plus (CF), b) RelyX Ceramic Primer (RXP), c) Futurabond U (FU). Brackets were virtually placed, transfer tray designed (OnyxCeph) and 3D-printed for indirect bonding with a) Transbond LV (TBL), b) Nexus NX3 (NX3), c) Maximum Cure (MC). SBS testing was performed with a universal testing machine after 24 h, 500 thermal cycles, 90 d. Directly bonded brackets to human enamel using Transbond XT Adhesive served as control. The adhesive remnant index (ARI) was evaluated. Data was analyzed with Shapiro-Wilk, Kruskal-Wallis and Dunn's post-hoc test with Bonferroni correction, Chi² test (p < 0.05), and the Weibull modulus was calculated.

RESULTS

SBS ranged from 0.1 to 15.5 MPa and were influenced mostly by the attachment material. NX3 generally showed the highest values (9.5-15.8 MPa). Initially RXP/TBL and FU/TBL presented the lowest values (4.3/4.8 MPa). Aging regimens reduced SBS of MC irrespective of pretreatment, after 90 d values ranged from 0.1 to 0.9 MPa. ARI 1 was predominant in all MC groups and FU/NX3, 2 and 3 in the other groups. Weibull moduli ranged between 0.15 (MC/RXP/500 TC) and 6.24 (NX3/RXP/500 TC).

SIGNIFICANCE

MC seems not to be suitable for indirect bonding using CAD/CAM transfer trays to zirconia. NX3 showed similar SBS values compared to the control, TBL lower.

Indirect bonding: an in-vitro comparison of a Polyjet printed versus a conventional silicone transfer tray

OBJECTIVES

To investigate and compare transfer accuracy between a Polyjet printed indirect bonding (IDB) tray (SureSmile, Dentsply Sirona, Richardson, TX, USA) and a conventional two-layered silicone tray.

MATERIALS AND METHODS

Plaster models of 24 patients were digitized with an intraoral scanner, and brackets and tubes were positioned virtually on the provider's homepage. IDB trays were designed over the planned attachments and Polyjet 3D-printed. For the conventional tray, brackets and tubes were bonded in their ideal positions manually before fabricating a two-layered silicone tray. For both trays, attachments were transferred indirectly to corresponding models. A second scan was performed of each bonded model to capture actual attachment positions, which were then compared to initial bracket positions using Geomagic Control (3D Systems Inc., Rock Hill, SC, USA). Linear and angular deviations were evaluated for each attachment within a clinically acceptable range of ≤0.2 mm and 1°. A descriptive statistical analysis and a mixed model were executed.

RESULTS

Both trays showed highest accuracy in the orobuccal direction (99.5% for the 3D-printed tray and 100% for the conventional tray). For the 3D-printed tray, most frequent deviations were found for torque (15.4%) and, for the silicone tray, for rotation (1.9%). A significant difference was observed for angular measurements (P = .004) between the trays.

CONCLUSIONS

Transfer accuracy of Polyjet printed IDB tray is not as high as transfer accuracy of the conventional silicone tray, though both trays show good results and are suitable for clinical application.

Transfer accuracy of 3D-printed trays for indirect bonding of orthodontic brackets

OBJECTIVES

To evaluate the transfer accuracy of 3D-printed indirect bonding trays constructed using a fully digital workflow in vivo.

MATERIALS AND METHODS

Twenty-three consecutive patients had their incisors, canines, and premolars bonded using fully digitally designed and 3D-printed transfer trays. Intraoral scans were taken to capture final bracket positioning on teeth after bonding. Digital models of postbonding scans were superimposed on those of corresponding virtual bracket setups, and bracket positioning differences were quantified. A total of 363 brackets were evaluated. One-tailed t-tests were used to determine whether bracket positioning differences were within the limit of 0.5 mm in mesiodistal, buccolingual, and occlusogingival dimensions, and within 2° for torque, tip, and rotation.

RESULTS

Mean bracket positioning differences were 0.10 mm, 0.10 mm, and 0.18 mm for mesiodistal, buccolingual, and occlusogingival measurements, respectively, with frequencies of bracket positioning within the 0.5-mm limit ranging from 96.4% to 100%. Mean differences were significantly within the acceptable limit for all linear dimensions. Mean differences were 2.55°, 2.01°, and 2.47° for torque, tip, and rotation, respectively, with frequencies within the 2°-limit ranging from 46.0% to 57.0%. Mean differences for all angular dimensions were outside the acceptable limit; however, this may have been due to limitations of scan data.

CONCLUSIONS

Indirect bonding using 3D-printed trays transfers planned bracket position from the digital setup to the patient's dentition with a high positional accuracy in mesiodistal, buccolingual, and occlusogingival dimensions. Questions remain regarding the transfer accuracy for torque, tip, and rotation.

Bracket transfer accuracy with two different three-dimensional printed transfer trays vs silicone transfer trays

OBJECTIVES

To compare the transfer accuracy of two different three-dimensional printed trays (Dreve FotoDent ITB [Dreve Dentamid, Unna, Germany] and NextDent Ortho ITB [NextDent, Soesterberg, the Netherlands]) to polyvinyl siloxane (PVS) trays for indirect bonding.

MATERIALS AND METHODS

A total of 10 dental models were constructed for each investigated material. Virtual bracket placement was performed on a scanned dental model using OnyxCeph (OnyxCeph 3D Lab, Chemnitz, Germany). Three-dimensional printed transfer trays using a digital light processing system three-dimensional printer and silicone transfer trays were produced. Bracket positions were scanned after the indirect bonding procedure. Linear and angular transfer errors were measured. Significant differences between mean transfer errors and frequency of clinically acceptable errors (<0.25 mm/1°) were analyzed using the Kruskal-Wallis and χ2 tests, respectively.

RESULTS

All trays showed comparable accuracy of bracket placement. NextDent exhibited a significantly higher frequency of rotational error within the limit of 1° (P = .01) compared with the PVS tray. Although PVS showed significant differences between the tooth groups in all linear dimensions, Dreve exhibited a significant difference in the buccolingual direction only. All groups showed a similar distribution of directional bias.

CONCLUSIONS

Three-dimensional printed trays achieved comparable results with the PVS trays in terms of bracket positioning accuracy. NextDent appears to be inferior compared with PVS regarding the frequency of clinically acceptable errors, whereas Dreve was found to be equal. The influence of tooth groups on the accuracy of bracket positioning may be reduced by using an appropriate three-dimensional printed transfer tray (Dreve).

Comparison of Bracket Failure Rate between Two Different Materials Used to Fabricate Transfer Trays for Indirect Orthodontic Bonding

BACKGROUND

Various techniques have been advocated for over half a century for the fabrication of transfer trays for indirect orthodontic bonding. Authors have aimed to provide better light curing and accuracy of bracket positioning to avoid bracket failure and get the best possible results.

AIM

This study is aimed to compare bracket failure rate when transfer trays were fabricated with a glue gun material and polylactic acid (PLA) filament for an indirect bonding procedure.

MATERIALS AND METHODS

Customized transfer trays were fabricated using a glue gun material and PLA filament, and an indirect bonding procedure was performed. Bracket failure was assessed at regular intervals with adhesive remnant index (ARI) scoring, and reasons for bracket failure were assessed.

RESULTS

Kolmogorov-Smirnov test was employed to test the normality of data. A Chi-square test was performed for the quantitative variables. Results showed higher bracket failure in the PLA transfer tray groups and in the mandibular arch, especially in the posterior region. Adhesive remnant index scores of 2 followed by 3 were prevalent, and the most common reason for bracket failure was an excessive force during PLA transfer tray retrieval followed by masticatory forces.

CONCLUSIONS

Both the transfer tray methods are effective for an indirect bonding procedure. Polylactic acid transfer trays showed more bracket failure as compared to glue gun transfer trays, especially in the mandibular posterior region due to excessive force applied during tray retrieval.

CLINICAL SIGNIFICANCE

This study aims to provide valuable information regarding the efficiency of various in-house methods of fabricating customized transfer trays and their effect on bracket failure rates.

Construction of an In Vivo Debonding Device and Comparison of Bracket Failure Rate and Debonding Force for Indirect Orthodontic Bonding

AIM

A major limitation of indirect bonding is incomplete penetration of the curing light through transfer trays, leading to inadequate curing of light-cure adhesive resin, causing bracket bond failure. Dual-cure adhesive resin is both light and chemically cured, which reduces the requirement of light for curing of the composite. Comparative evaluation of bracket failure rate and bond strength between dual-cure composite and light-cure composite for indirect orthodontic bonding of brackets.

MATERIALS AND METHODS

A split-mouth randomized clinical study was carried out in 51 patients (30 females and 21 males). Indirect orthodontic bonding using Erkogum as adhesive to attach the bracket to cast and glue gun material was utilized to form a transfer tray. Conventional light-cure and dual-cure adhesive resins were compared with regard to their bracket failure rate, adhesive remnant index score, and in vivo clinical bond strength.

RESULTS

Kolmogorov-Smirnov test was employed to test the normality of data. Mann-Whitney U test and Chi-square test were performed for the quantitative variables and it was observed that both the groups showed similar results for the parameters being measured. The mandibular arch showed more bracket failure, the dual-cure composite group showed more bracket failure, however, the adhesive remnant index (ARI) score for both the groups was similar. No statistically significant difference was seen concerning the clinical bond strength between the two adhesive resins.

CONCLUSION

Dual-cure adhesive system can be used for indirect bonding in orthodontics. The mandibular arch had a higher bond failure in the second premolar region. The sequence of bond failure was concordant among both the adhesive groups. However, dual-cure adhesive invariably showed more bracket failure. The highest bond strength was observed for the maxillary canine brackets in the light-cure group, and mandibular canine brackets in the dual-cure group. Whereas, the weakest bond strength in the light-cure group was observed for the mandibular second premolar brackets and for maxillary second premolar brackets in the dual-cure group. There was no significant difference between the in vivo clinical bond strength between the two adhesive systems. On debonding, majority of the adhesive was observed to be on the tooth surface.

CLINICAL SIGNIFICANCE

This study signifies that both light-cure and dual-cure resins can be used for indirect bonding procedures but light-cure composite resin shows a lower bracket failure rate as compared to dual-cure composite resin.

Effect of Direct versus Indirect Bonding Technique on the Failure Rate of Mandibular Fixed Retainer-A Systematic Review and Meta-Analysis

INTRODUCTION

Fixed retainer failure is a common cause of relapse and may require additional orthodontic treatment. The two main methods for bonding the mandibular fixed retainer include direct and indirect techniques. This topic has not been explored previously in a systematic review. Therefore, the objective of this systematic review was to evaluate the effect of direct versus indirect bonding technique on the failure rate of mandibular fixed retainer.

METHODS

Online databases (PubMed, Dental and Oral Science, CINAHL, and Cochrane Central Register of Controlled Trials, Scopus) were systematically searched electronically for articles up until April 2021. Google Scholar and clinicaltrials.gov databases were utilized for hand searching. Randomized, non-randomized clinical trials and cohort studies on human subjects were considered regardless of language or year of publication. Orthodontic patients in their retention phase (mandibular 3×3 fixed retainer), in which the retainer was bonded using direct bonding technique as control and indirect as intervention were included. The outcome assessed was retainer failure rate. Two authors independently examined and extracted the data from the studies that satisfied the inclusion criteria. Risk of bias in clinical trials was assessed using the Cochrane Collaboration's tool, whereas risk of bias in cohort studies was assessed using the Newcastle-Ottawa Scale. The meta-analysis was conducted using the RevMan software V.5.3.5.22. The outcome was estimated using weighted average difference and 95% confidence intervals (CIs). The studies' heterogeneity was assessed using Cochrane's heterogeneity test (I2 Test).

RESULTS

Four articles fulfilling the inclusion criteria were included in qualitative and quantitative synthesis. Retainer failure rates were analysed in a total number of 266 patients bonded with mandibular 3×3 retainers after orthodontic therapy. Direct bonding technique of fixed retainer on 131 patients was compared with indirect technique on 135 patients. There was no statistically significant difference in the rate of retainer failure between the two methods (95% CI, 0.67, 1.40).

CONCLUSIONS

Within the limitations of insufficient evidence this systematic review and meta-analysis concluded that there is no difference in the failure rate of mandibular fixed retainers between direct and indirect bonding techniques. Due to the scarcity of available data, further studies are needed to establish definitively one's clinical benefit over the other.

Transfer accuracy of four different lingual retainer transfer methods using digital orthodontic models: An in vivo comparative study

OBJECTIVES

To compare the transfer accuracy of four different lingual retainer (LR) transfer methods using three-dimensional digital models.

MATERIALS AND METHODS

Four groups of 17 patients each were created: finger transfer (FT), silicone key transfer (SKT), acrylic resin transfer (ART), and indirect bonding (IDB). At the end of orthodontic treatment, the mandibular dental casts of patients were scanned with the LR wire. Then, intraoral scanning of the mandibular arches was performed after bonding the retainer wires. Linear and angular measurements were made using software on superimposed digital models.

RESULTS

Horizontal and vertical errors among the teeth were not significantly different among the FT, SKT, and ART groups. However, in the IDB group, linear transfer errors showed significant differences among the different teeth. The tip and rotation errors in the FT group were not significantly different among the teeth. The angular errors were lower in canines than in the incisors. In all measured parameters, the SKT group showed the lowest errors, whereas the FT group had the highest transfer errors in all parameters except vertical.

CONCLUSIONS

Among the transfer methods tested, SKT was determined to have the highest clinical accuracy.

Comparison of the transfer accuracy of two digital indirect bonding trays for labial bracket bonding

OBJECTIVES

To compare the transfer accuracy of two digital transfer trays, the three-dimensional printed (3D printed) tray and the vacuum-formed tray, in the indirect bonding of labial brackets.

MATERIALS AND METHODS

Ten digital dental models were constructed by oral scans using an optical scanning system. 3D printed trays and vacuum-formed trays were obtained through the 3Shape indirect bonding system and rapid prototyping technology (10 in each group). Then labial brackets were transferred to 3D printed models, and the models with final bracket positioning were scanned. Linear (mesiodistal, vertical, buccolingual) and angular (angulation, torque, rotation) transfer errors were measured using GOM Inspect software. The mean transfer errors and prevalence of clinically acceptable errors (linear errors of ≤0.5 mm and angular errors of ≤2°) of two digital trays were compared using the Mann-Whitney U-test and the Chi-square test, respectively.

RESULTS

The 3D printed tray had a lower mean mesiodistal transfer error (P < .01) and a higher prevalence of rotation error within the limit of 2° (P = .03) than did the vacuum-formed tray. Linear errors within 0.5 mm were higher than 90% for both groups, while torque errors within 2° were lowest at 50.9% and 52.9% for the 3D printed tray and vacuum-formed tray, respectively. Both groups had a directional bias toward the occlusal, mesial, and buccal.

CONCLUSIONS

The 3D printed tray generally scored better in terms of transfer accuracy than did the vacuum-formed tray. Both types of trays had better linear control than angular control of brackets.

Standard vs computer-aided design/computer-aided manufacturing customized self-ligating systems using indirect bonding with both

OBJECTIVE

To compare treatment duration and quality between standard vs computer-aided design/computer-aided manufacturing (CAD/CAM) customized self-ligating systems using indirect bonding with both.

MATERIALS AND METHODS

This comparative trial included 24 patients: 12 treated with a CAD/CAM custom indirect bonding self-ligating system (CAD/CAM) and 12 others treated with an indirect bonding self-ligating standard system (I-STD). For each group, overall orthodontic treatment (OT) time was calculated and included the time needed to place each arch as well as the duration of the alignment and fine-tuning phases. The quality of the final result was analyzed using the American Board of Orthodontics Cast-Radiograph Evaluation. Patient-reported outcome measures (PROMs) were also evaluated.

RESULTS

Patient characteristics were similar between the 2 groups except for age, which was slightly lower in the I-SDT group. Overall OT time was increased by 26% in the I-STD group compared with the CAD/CAM group (497 ± 40 days vs 393 ± 55 days, P = 0.0002) due to a shorter fine-tuning phase in the latter group (P<0.01). No difference was found between the groups for alignment phase. Quality of the final result was similar (I-STD, 25.7 ± 6.1; CAD/CAM, 21.6 ± 6.3) among the groups. Finally, no difference was found in the PROMs variables.

CONCLUSIONS

Despite a 26% longer OT time when compared with the CAD/CAM customized bracket system, the indirect bonding self-ligating bracket system demonstrated the same quality of treatment. PROMs demonstrated a high level of acceptance and satisfaction for both techniques.

Bond strength of indirect bonded brackets in orthodontic adhesives with different viscosities

The aim of this study was to assess the effects of three adhesives with different viscosities and an adhesion promoter on the shear bond strength (SBS) of orthodontic brackets bonded to human premolars with an indirect bonding system (IDBS). High, medium and low viscosity IDBSs with and without application of the adhesion promoter were used. The mean SBSs of the high and low viscosity IDBSs were significantly higher than that of the medium viscosity IDBS. Application of the adhesion promoter significantly increased the SBSs. The adhesion promoter significantly increased the surface roughness and free-energy of enamel. Irrespective of application or nonapplication of the adhesion promoter, the high and low viscosity IDBSs are effective for bracket bonding. Use of the medium viscosity IDBS in combination with the adhesion promoter is recommended for obtaining a clinically acceptable SBS.

Digital assessment of direct and virtual indirect bonding of orthodontic brackets: A clinical prospective cross-sectional comparative investigation

OBJECTIVE

The objective of this report is to use in orthodontic patients the methods of virtual indirect bonding and direct bonding using eye vision or loupes in order to compare their accuracy in the three dimensions of space.

MATERIAL AND METHODS

Brackets were directly placed by one clinician to 18 patients with a total number of 298 permanent teeth. Then loupes were used to improve bracket positioning. Intraoral scanning of the dental arches was performed before bonding, after direct bonding and after the use of loupes. Subsequently, an orthodontic software was used to virtually indirectly bond the brackets on the first intraoral scanning taken before bonding. A three-dimensional mesh processing software was used to superimpose the three scans and to perform measurements in the mesio-distal and occlusal-gingival dimensions as well as in the mesio-distal angulation.

RESULTS

Virtual indirect bonding was more accurate in bracket positioning compared to direct bonding by eye vision or using loupes in all teeth and most of the teeth groups measured. Specific teeth and locations in the dental arch areas exhibited more bonding inaccuracies in the two direct bonding groups as compared to virtual indirect bonding. The use of loupes did not significantly increase the bonding accuracy compared to direct vision.

CONCLUSION

Indirect virtual bonding facilitated accurate bracket positioning compared to direct vision or with loupes direct bonding in the dimensions and angulation measured.

Comparison of three-dimensional printing guides and double-layer guide plates in accurate bracket placement

Background

In the current study, we aimed to evaluate the accuracy of indirect bonding by either three-dimensional (3D) printing guides or double-layer guide plates. The results may serve as a clinical reference for bracket placements.

Methods

In total, 140 teeth were collected and arranged into five pairs of full dentition. The marking points were labeled on the buccal/labial surface of the crown in these orthodontic study models. (1) 3D printing guide: A digital profile was generated using an intraoral scanner. Two types of indirect bonding guide, namely the whole denture type and the single tooth type, were designed with the 3Shape TRIOS® Standard intraoral scanner and fabricated using 3D printing technology. (2) Double-layer guide plate: A working model was obtained by replicating the experimental models, and the double-layer guide plate was then made of the inner layer soft film (1.0 mm thickness) and the outer layer hard film (0.6 mm or 0.8 mm thickness). Brackets were transferred from working models to study models by the indirect bonding trays. We measured and analyzed the distance between marking points and bracket placement. Statistical analysis was done using SPSS 20.0 software. The accuracy of indirect bonding between 3D printing guide and double-layer guide plate was compared using paired t-test.

Results

According to our data, there was a significant difference between the 0.6 mm group and 0.8 mm group when the brackets were indirectly adhered using double-layer guide plates (p = 0.036). However, no statistical significance in bracket positioning accuracy was revealed between two types of 3D printing guide (p = 0.078), as well as between the 3D printing guide group and the 0.6 mm double-layer guide plate group (p = 0.069).

Conclusions

When applying double-layer guide plates for indirect bonding, the 0.6 mm group is more accurate than the 0.8 mm group. When utilizing 3D printing guides for indirect bonding, whole denture type is more accessible than single tooth type but with no significant difference in accuracy. The accuracy of indirect bonding is comparable when using 3D printing guides (whole denture type) and double-layer guide plates (0.6 mm).

Accuracy evaluation of bracket repositioning by indirect bonding: hard acrylic CAD/CAM versus soft one-layer silicone trays, an in vitro study

OBJECTIVES

Rapid development of digital technologies and 3D printing provide new tools for orthodontic indirect bonding. The purpose of this in vitro study is to evaluate the clinical acceptability of hard CAD/CAM indirect bonding tray.

MATERIAL AND METHODS

Ten soft silicone transfer trays and ten hard CAD/CAM trays were produced, and 200 brackets were placed on them. The brackets were then transferred to twenty stereolithography -printed models by indirect bonding. These models were scanned and digitally compared with the reference model by three-dimensional superimpositions (GOM software). The linear and angular measurements were collected and analyzed.

RESULTS

For the CAD/CAM trays, 100% of the mesiodistal, vertical, and transverse measurements of incisors were within the clinically acceptable range of the American Board of Orthodontists (ABO) standards. More specifically, the clinically acceptable linear measurements were between 97 and 100% for silicone trays while they were between 89 and 100% for CAD/CAM trays. The clinically acceptable angular measurements varied between 87 and 100% for the silicone trays and between 79 and 100% for the CAD/CAM trays. Silicone trays were more precise than CAD/CAM trays. The difference was significant for all linear and angular measurements.

CONCLUSIONS

While the CAD/CAM group shows clinically acceptable results according to the ABO, silicone remains to be more precise than CAD/CAM for transfer trays and is therefore still the reference.

CLINICAL RELEVANCE

We demonstrate here that the orthodontic indirect bondings, whether they are realized using silicone transfer trays or CAD/CAM trays, are clinically acceptable in terms of the repositioning accuracy of brackets.

Reproducibility of digital indirect bonding technique using three-dimensional (3D) models and 3D-printed transfer trays

OBJECTIVE

To evaluate the reproducibility of digital tray transfer fit on digital indirect bonding by analyzing the differences in bracket positions.

MATERIALS AND METHODS

Digital indirect bonding was performed by positioning brackets on digital models superimposed by tomography using Ortho Analyzer (3Shape) software. Thirty-three orthodontists performed indirect bonding on prototyped models of the same malocclusion using prototyped transfer trays for two types of brackets (MiniSprint Roth and BioQuick self-ligating). The models with brackets were scanned using an intraoral scanner (Trios, 3Shape). Superimpositions were made between the digital models obtained after indirect bonding and those from the original virtual setup. To analyze the differences in bracket positions, three planes were examined for each bracket: vertical, horizontal, and angulation. Three orthodontists repeated indirect bonding after 15 days, and Bland-Altman plots and intraclass correlation coefficients were used to evaluate inter- and intraevaluator reproducibility and reliability, respectively. Repeated-measures analysis of variance (ANOVA) was used to analyze the differences between bracket positions, and multivariate ANOVA was used to evaluate the influence of orthodontists' experience on the results.

RESULTS

Differences between bracket positions were not statistically significant, except mesial-distal discrepancies in the BioQuick group (P = .016). However, differences were not clinically significant (horizontal varied from 0.04 to 0.13 mm; angulation, 0.45° to 2.03°). There was no significant influence of orthodontist experience and years of clinical practice on bracket positions (P = .314 and P = .158). The reproducibility among orthodontists was confirmed.

CONCLUSIONS

The reproducibility of digital indirect bonding was confirmed in terms of bracket positions using three-dimensional printed transfer trays.

Effectiveness, efficiency and adverse effects of using direct or indirect bonding technique in orthodontic patients: a systematic review and meta-analysis

Background

The direct and indirect bonding techniques are commonly used in orthodontic treatment. The differences of the two techniques deserve evidence-based study.

Materials and methods

Randomized controlled trials (RCTs), wherein direct and indirect bonding techniques were used in orthodontic patients were considered. The MEDLINE, EMBASE, CENTRAL and Web of Science databases were searched to identify relevant articles published up to December 2018. Grey literature was also searched. Two authors performed data extraction independently and in duplicate using the data collection form. The included trials were assessed using the Cochrane risk of bias assessment tool.

Results

Of the 1557 studies screened, 42 full articles were scrutinized and assessed for eligibility. Eight RCTs (247 participants) were finally included for the analyses. The qualitative synthesis showed that no significant difference existed in the accuracy of bracket placement and oral hygiene status between the two bonding techniques. The indirect bonding was found to involve less chairside time but more total working time compared with the direct bonding. The meta-analysis on bond failure rate demonstrated no significant difference between the direct and indirect bonding (RR = 1.13, 95% CI = 0.78–1.64, I² = 22%, P = 0.50). Consistent results were obtained in the subgroup analyses and sensitivity analyses.

Conclusion

Weak evidence suggested that the direct and indirect bonding techniques had no significant difference in bracket placement accuracy, oral hygiene status and bond failure rate, for bonding orthodontic brackets. The indirect bonding might require less chairside time but more total working time in comparison with the direct bonding technique. High-quality well-designed randomized controlled trials are needed before a conclusive recommendation could be made.

Electronic supplementary material

The online version of this article (10.1186/s12903-019-0831-4) contains supplementary material, which is available to authorized users.

Comparison of Shear Bond Strength of Orthodontic Brackets Using Direct and Indirect Bonding Methods in Vitro and in Vivo

Aim:

Aim of article was to compare the shear bond strength of indirectly and directly bonded orthodontic brackets.

Materials and methods:

The experimental in vitro study included 60 maxillary and mandibular premolars. Teeth were mounted on cold-cure acrylic blocks for each tooth separately and divided into two groups: directly bonded brackets (30 teeth) and indirectly bonded brackets (30 teeth). Brackets (Discovery, Roth 0.022”, Dentaurum, Ispringen, Germany) were bonded using Transbond XT (3M Unitek, Monrovia, CA, USA) in direct method, while in indirect technique, a combination of Transbond XT and Sondhi Rapid Set (3M Unitek, Monrovia, CA, USA) was used. The shear bond strength and adhesive remnant index (ARI) were evaluated. The in vivo study included 30 subjects - 15 with indirectly bonded brackets and 15 with directly bonded brackets. Survival rate was assessed during the period of 6 months.

Results:

No statistically significant difference in the shear bond strength was found in direct (7.48±1.61 MPa) and indirect labial bonding methods (7.8.2±1.61 MPa). Both methods produced very similar amount of adhesive remnant on tooth surface (median = 1; interquartile range 1–2). There were no significant differences in bracket survival rate between methods.

Conclusion:

Regarding the shear bond strength, adhesive remnant on tooth surface, and survival rate, both indirect and direct methods of orthodontic bracket bonding seem to be equally valuable methods in clinical practice.

Indirect Bonding Revisited

In recent years, the popularity of indirect bonding increased due to advantages such as reduction of chair time and enhancement of patient comfort. Although the indirect bonding technique has improved over the years, the literature has shown different techniques of bracket placement; furthermore, new materials were specially developed for this technique. The aim of this article is to provide a review of the literature, advantages, disadvantages, and laboratory and clinical stages of the indirect bonding technique.

Self ligating lingual appliance

Adult demand for orthodontics has grown considerably over the past 10 years propelling increased demand for Esthetic Orthodontics. Lingual appliances are a viable option toward providing Esthetic Orthodontics. The lingual surface of the teeth has a unique morphology that makes it difficult to place brackets in ideal positions. Indirect bonding has become the established methods of overcoming these discrepancies, along with the latest designs of self ligating brackets which offer more efficient mechanics and shorter treatment time.

Transfer accuracy of vinyl polysiloxane trays for indirect bonding

OBJECTIVE

To elicit the magnitude, directional bias, and frequency of bracket positioning errors caused by the transfer of brackets from a dental cast to the patient's dentition in a clinical setting.

MATERIALS AND METHODS

A total of 136 brackets were evaluated. The brackets were placed on dental casts and scanned using cone beam computed tomography (CBCT) to capture 3-D positioning data. The brackets were then transferred to the patient's dentition with an indirect bonding method using vinyl polysiloxane (VPS) trays and later scanned using CBCT to capture the final bracket positioning on the teeth. Virtual models were constructed from the two sets of scan data and digitally superimposed utilizing best-fit, surface-based registration. Individual bracket positioning differences were quantified using customized software. One-tailed t tests were used to determine whether bracket positioning was within limits of 0.5 mm in the mesiodistal, buccolingual, and vertical dimensions, and 2° for torque, tip, and rotation.

RESULTS

Individual bracket positioning differences were not statistically significant, indicating, in general, final bracket positions within the selected limits. Transfer accuracy was lowest for torque (80.15%) and highest for mesiodistal and buccolingual bracket placement (both 98.53%). There was a modest directional bias toward the buccal and gingival.

CONCLUSION

Indirect bonding using VPS trays transfers the planned bracket position from the dental cast to the patient's dentition with generally high positional accuracy.

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.