Do we need primer for orthodontic bonding? A randomized controlled trial

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.

Comparative Assessment of Bracket Bond Failure Rates of a Novel Chitosan-Based Orthodontic Primer: An In Vivo Split-Mouth Study

Introduction An unavoidable side effect of orthodontic fixed appliance therapy is the demineralization of the enamel surface surrounding the bracket at the adhesive and tooth interface due to a microgap formation, which serves as a nidus for biofilm growth. Due to this, it is advantageous to include antibacterial agents in orthodontic primers without affecting their clinical properties. The aim of this study was to compare the in vivo bracket bond failure rates of a novel chitosan-based primer with a conventional orthodontic primer. Materials and methods Fifty-four subjects and 1,080 brackets were included in this study. At the end of six months, 45 subjects and 960 brackets bonded using novel chitosan-based primers and conventional primers (Anabond, Anabond Stedman Pharma Research Pvt Ltd, Chennai, India). Each was evaluated for a bracketed bond failure rate. Descriptive statistics and Chi-square tests were used for statistical analysis. Results The results revealed that the bracket bond failure rate in Group 1 (novel chitosan-based primer) was 27 brackets (3%) and 23 brackets in Group 2 (conventional primer) (2.5%), with no statistically significant difference between the two groups (p>0.05). There was a statistically significant difference in the bracket failure rate between the maxillary arch (2%) and the mandibular arch (3.5%) (p<0.05). Conclusion Brackets bonded with the chitosan-modified novel orthodontic primer showed no statistically significant difference in bracket bond failure rate when compared to the conventional primer. Bond failure rates were higher in the mandibular teeth when compared to the maxillary teeth.

Pulp chamber temperature rise in light-cure bonding of brackets with and without primer, in intact versus restored teeth

OBJECTIVE

To evaluate the pulp chamber temperature rise (PCTR) in light-cure bonding of brackets with and without primer, in intact and restored mandibular central incisors (M1), maxillary first premolars (Mx4), and mandibular third molars (M8).

MATERIAL AND METHODS

Ninety human teeth were included: M1 (n=30), Mx4 (n=30), and M8 (n=30). Light-cure bonding of brackets was performed in intact (n=60) and restored (n=30) teeth, with primer (n=60) or without (n=30) primer. PCTR was defined as the difference between initial (T0) and peak temperatures (T1), recorded with a thermocouple during light-cure bonding. Differences on PCTR between bonding techniques (primer vs. no primer), teeth types (M1 vs. Mx4 vs. M8), and teeth condition (intact vs. restored) were estimated by ANCOVA, with α=5%.Results: PCTR was significantly higher with the use of primer (2.05 ± 0.08oC) than without primer (1.65 ± 0.14oC) (p=0.02), and in M1 (2.23 ± 0.22oC) compared to Mx4 (1.56 ± 0.14oC) (p<0.01). There was no difference in the PCTR in M8 (1.77 ± 0.28oC) compared to M1 or Mx4 (p>0.05), and no difference between intact (1.78 ± 0.14oC) and restored (1.92 ± 0.08oC) teeth (p=0.38). There was no influence of dentin enamel thickness in the PCTR (p=0.19).

CONCLUSION

PCTR was higher in light-cure bonding of brackets with primer, especially in M1. Light-cure bonding seems less invasive without primer.

Bracket Bond Failures: Incidence and Association with Different Risk Factors-A Retrospective Study

BACKGROUND

Bracket bonding failure is one of the relevant problems in fixed orthodontics therapy, which affects the total treatment and quality of treatment results. The purpose of this retrospective study was to evaluate the frequency of bracket bond failure and find out risk factors.

METHODS

A total of 101 patients with an age range of 11-56 years were included in this retrospective study and treated for a mean period of 30.2 months. Inclusion criteria were: males and females with permanent dentition and completed orthodontic treatment in both fully bonded dental arches. Risk factors were calculated using binary logistic regression analysis.

RESULTS

The overall bracket failure rate was 14.65%. The bracket failure rate was significantly higher in the younger patients' group (p = 0.003). In most cases, patients experienced bracket failures in the first month of the treatment. Most of the bracket bond failures occurred on the left lower first molar (29.1%) and were twice as common in the lower dental arch (66.98%). Patients with increased overbite had an increased likelihood of bracket loss (p = 0.042). Class II malocclusion increased the relative risk of bracket failure, while Class III decreased the rate of bracket failure, but the difference was not statistically significant (p = 0.093).

CONCLUSIONS

The bracket bond failure rate was higher in younger patients than in older patients. Brackets placed on mandibular molars and premolars had the highest failure rate. Class II was associated with an increased bracket failure rate. Increased overbite statistically significantly increases bracket failure rate.

Evaluation of shear bond strength of orthodontic adhesives with integrated primer: A comparative study

Objectives:

The study aimed to compare the shear bond strength (SBS) of three orthodontic adhesives with integrated primer, with those of self-etching and conventional bonding adhesives.

Material and Methods:

One hundred extracted premolars were randomly allocated to five groups. Brackets were bonded using three adhesives with integrated primer (GC Ortho Connect™, Biofix, and Orthocem). A group of brackets was bonded with the conventional bonding procedure (Transbond XT) and one group was bonded with a self-etching primer (Transbond™ Plus). All samples were subjected to thermal aging (5000 cycles: At 5°C and 55°C media). The compressive strength test was performed and the maximum load when the bracket detached was recorded. The amount of residual adhesive (ARI) remaining on the tooth surface was assessed visually.

Results:

Significantly higher SBS values were recorded with the conventional technique (14.01 ± 5.79 megapascals [MPa]), compared to other groups except for GC Ortho Connect™ (11.86 ± 3.83 MPa). There was no significant difference between the self-etching group and the groups containing integrated primer samples. However, one of the adhesives with integrated primer presented SBS values near-slightly below the limit considered clinically successful (7.65 ± 3.71 MPa). The ARI scores varied between adhesive groups; GC Ortho Connect™ and the self-etching primer samples showed statistically significantly higher scores compared to the three other groups.

Conclusion:

Clinically successful bonding values were achieved with two out of three different adhesives with integrated primer. One of the adhesives with integrated primer provided a similar SBS value to the tri-step conventional bonding procedure. ARI scores varied independently from SBS values.

Influence of Primer Pre-curing and Co-curing on Shear Bond Strength of Orthodontic Brackets Using Three Light-cure Adhesive Systems: An In Vitro Study

AIM

This study aimed to evaluate the shear bond strength (SBS) of orthodontic brackets with primer pre-curing and co-curing using three light cure adhesive systems.

MATERIALS AND METHODS

In this in vitro study, 102 extracted premolar teeth mounted on self-cure acrylic resin blocks were separated into six groups based on primer pre-curing and co-curing with each group receiving stainless steel orthodontic premolar brackets bonded to the buccal surfaces. The following adhesives were used: Transbond XT (3M Unitek, CA, USA), Orthofix (Anabond Stedman, India), and Enlight (Ormco, India). In the groups with pre-curing, the primer was pre-cured for 20 seconds while in the groups with co-curing, the primer and adhesive were cured together. Shear bond strength tests and Adhesive Remnant Index (ARI) were assessed followed by an scanning electron microscope (SEM) view (×3000) of the enamel surface after debonding. Statistical analysis was done using a one-way analysis of variance (ANOVA) test.

RESULTS

The descriptive statistics in the pre-cured groups showed a statistically significant difference. The highest mean SBS was observed for group I, i.e., Transbond XT with primer pre-curing (20.56 ± 3.22 MPa). The lowest mean SBS was for group IV, i.e., Orthofix with primer co-curing (7.57 + 0.49 MPa). The results of ANOVA revealed a significant difference among the groups. The ARI scoring and the SEM analysis also confirmed this finding.

CONCLUSION

Shear bond strength of orthodontic brackets with primer pre-curing showed a better bond strength than brackets with co-curing. The ARI data suggested that the majority of bracket failure happened at the resin-bracket interface. Scanning electron microscope analysis also confirmed the ARI and SBS findings.

CLINICAL SIGNIFICANCE

During the bonding of orthodontic brackets, the primer can be co-cured where the primer and adhesive resin are cured simultaneously or pre-cured where the primer is cured separately. Most orthodontic clinicians to save time co-cure primer. Both these methods affect the SBS of brackets.

Comparison of bond strength of metal and ceramic brackets with or without primer

Background:

Aim:

Material and Method:

Result:

Conclusion:

Universal Adhesive for Fixed Retainer Bonding: In Vitro Evaluation and Randomized Clinical Trial

This study aims to assess the efficacy of a universal adhesive (Scotchbond Universal, 3M ESPE) (SB) in total-etch mode, compared to a traditional orthodontic primer (Transbond XT Primer, 3M ESPE) (XT Primer), to perform bonding of orthodontic fixed retainers along with the Transbond XT Light Cure Adhesive Paste (3M ESPE). For the in vitro study, a round section wire (Ortosmail Krugg) was bonded using XT Primer for 20 bovine incisors (Group 1) and SB for other 20 (Group 2). Samples were debonded in a universal testing machine applying a tangential force to specimens (crosshead speed of 1 millimeter per minute). Shear bond strength (SBS) and adhesive remnant index (ARI) scores were calculated. For the in vivo study, 100 patients needing upper and lower canine-to-canine fixed retainers after orthodontic treatment were randomly assigned to two groups of 50 participants each, i.e., group 1 (retainer bonding with XT Primer) and group 2 (retainer bonding with SB). Over two years, examinations were carried out monthly, and detachments were registered by considering the teeth and arches affected. In vitro, no statistically significant differences in SBS and ARI scores were demonstrated between the two groups, both showing a mean bond strength of about 12 MPa and major frequency of ARI “2” (>50% remnant adhesive on the enamel). Conversely, a significantly lower failure rate over 2 years was assessed clinically for group 2 in both arches. Independently of the adhesive and arch, incisors reported a significantly higher failure rate than canines. Scotchbond Universal used in total-etch mode could be a valid alternative to the traditional orthodontic Transbond XT Primer.

Single-component orthodontic adhesives: comparison of the clinical and in vitro performance

OBJECTIVES

To investigate the clinical and in vitro performance of single-component orthodontic adhesives under metal brackets.

MATERIALS AND METHODS

Bimaxillary orthodontic treatment was required for sixty patients and 60 premolar teeth were divided into three groups (n: 20). The single-component orthodontic adhesives Biofix and GC Ortho Connect (GC) that did not require primers were compared to the control group using Transbond XT, which was applied with a primer. For each patient, total bonding time was measured. The Adhesive Remnant Index (ARI_(Bracket)) score was noted over 12 months. In vitro tests were used to evaluate specimens, shear bond strength (SBS), ARI_(Bracket), and Enamel Surface Index (ESI). After in vitro debonding, the enamel surface and bracket base were analyzed using scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX).

RESULTS

Clinical failure rate with primer was 9.0%, while it was 8.0 and 10.0 for GC and Biofix, respectively. The mean in vitro SBS values of the Biofix, GC, and Transbond XT groups were 8.21, 8.07, and 7.37 MPa, respectively. There were no statistically differences in clinical failure (p = 0.160) and SBS values (p = 0.158). Mean differences in bond-up time per jaw were 9.65, 10.51, and 11.97 min, which were statistically significant (p = 0.0001).

CONCLUSION

Single-component adhesives had acceptable SBS values and enamel effects according to SEM-EDX analysis. Clinically, bonding failure was not shown statistically inferior to bonding with primer. There was also a significant difference in bond-up times.

CLINICAL RELEVANCE

Considering an intensely working clinic with bonding processes for at least two jaws per day, this means a saving of the chair time of 1 patient per week. However, better saliva contamination and moisture control with lack of the primer stage and, thereby, an acceptable bracket failure rate will bring clinically significant results with less chair time for clinicians.

Temperatures in the pulpal cavity during orthodontic bonding using an LED light curing unit : An in vitro pilot study

PURPOSE

During bracket bonding, patients often report about thermosensitivity. The reason could be that modern light emitting diode (LED) light curing units run with intensities up to 3200 mW/cm². In this in vitro pilot study with nonpulpal circulation approaches, the temperatures in the pulpal cavity were measured.

METHODS

The study included 60 extracted teeth divided into four equal groups: lower and upper incisors, premolars and molars. Starting at 37 °C (body temperature) as the reference, the temperature increase was measured for the first series on each tooth without a bracket, without and with a recommended hygienic barrier case for the LED light curing unit, and exposition to light once versus twice. The distance between the tooth and light curing unit was 3 mm. In the second test series, a metal bracket was also bonded to each tooth. In the third series, the light exposition distance was increased to 4 mm.

RESULTS

In all three test series, significant intrapulpal temperature increase was found: The highest temperatures were recorded after exposure to light once without the hygienic barrier case. In the first test series, this approach showed temperatures even higher than 42.5 °C in the lower incisors (average 42.99 ± 2.23 °C) and premolars (average 42.94 ± 2.15 °C).

CONCLUSIONS

Significant increases in the temperature of the pulpal cavity (up to 42.5 °C) may occur during bonding brackets according to the manufacturer's recommendation with an LED light curing unit with in vitro nonpulpal circulation approaches. Therefore it could be reasonable to critically question the recommendation of the manufacturer.

Orthodontic bonding procedures significantly influence biofilm composition

BACKGROUND

Because changes in surface properties affect bacterial adhesion, orthodontic bonding procedures may significantly influence biofilm formation and composition around orthodontic appliances. However, most studies used a mono-species biofilm model under static conditions, which does not simulate the intraoral environment and complex interactions of oral microflora because the oral cavity is a diverse and changeable environment. In this study, a multi-species biofilm model was used under dynamic culture conditions to assess the effects of the orthodontic bonding procedure on biofilm formation and compositional changes in two main oral pathogens, Streptococcus mutans and Porphyromonas gingivalis.

METHODS

Four specimens were prepared with bovine incisors and bonding adhesive: untreated enamel surface (BI), enamel surface etched with 37% phosphoric acid (ET), primed enamel surface after etching (PR), and adhesive surface (AD). Surface roughness (SR), surface wettability (SW), and surface texture were evaluated. A multi-species biofilm was developed on each surface and adhesion amounts of Streptococcus mutans, Porphyromonas gingivalis, and total bacteria were analyzed at day 1 and day 4 using real-time polymerase chain reaction. After determining the differences in biofilm formation, SR, and SW between the four surfaces, relationships between bacteria levels and surface properties were analyzed.

RESULTS

The order of SR was AD < PR < BI < ET, as BI and ET showed more irregular surface texture than PR and AD. For SW, ET had the greatest value followed by PR, BI, and AD. S. mutans and P. gingivalis showed greater adhesion to BI and ET with rougher and more wettable surfaces than to AD with smoother and less wettable surfaces. The adhesion of total bacteria and S. mutans significantly increased over time, but the amount of P. gingivalis decreased. The adhesion amounts of all bacteria were positively correlated with SR and SW, irrespective of incubation time.

CONCLUSIONS

Within the limitations of this study, changes in SR and SW associated with orthodontic bonding had significant effects on biofilm formation and composition of S. mutans and P. gingivalis.

A Clinical Comparison of Failure Rates of Metallic and Ceramic Brackets: A Twelve-Month Study

Objective

Clinical comparison of the survival rates between stainless steel and ceramic brackets over a 12-month period.

Materials and Methods

The study involved 20 consecutive patients with diagnosed malocclusion that required two-arch fixed appliance treatment. The participants were randomly divided into two 10-member groups. Group 1 was treated with Abzil Agile (3M Unitek) stainless steel brackets; group 2 was treated with Radiance (American Orthodontics) monocrystalline ceramic brackets. All the brackets were bonded by the same operator. Over the next 12 months, all bracket failures were recorded with each appointment. The received data were processed statistically using the Mantel–Cox test, Kaplan–Meier method, and Cox hazard model.

Results

A total of 381 brackets were bonded, 195 of which were metallic brackets and 186 were ceramic ones. In the 12-month observation period, there were 14 metal (7.2%) and 2 ceramic bracket (1.1%) failures. The overall failure rate was 4.2% (n = 16). The majority of failures (14 brackets; 87.5%) occurred during the first 6 months of the experiment, 12 (83%) of which were metal brackets and 2 (100%) were ceramic brackets. The statistical analysis revealed significant differences between the groups (p < 0.05).

Conclusions

Metal brackets demonstrated significantly higher failure rates than ceramic brackets for both 6- and 12-month observation periods (p < 0.05). The 6% difference between the brackets is clinically significant as it corresponds to one additional failure within 12 months.

Clinical performance of precoated brackets and self-etch bonding technique: a prospective comparative study

OBJECTIVE

The aim was to compare the clinical performance of uncoated and adhesive precoated brackets bonded with either self-etching primer (SEP) or conventional two-step etch and primer method (CEM).

SUBJECTS AND METHODS

The sample consisted of 63 patients with a mean age of 15.20 ± 1.6 years. In group I (n = 15), uncoated brackets and CEM; in group II (n = 16), precoated brackets and CEM; in group III (n = 16), uncoated brackets and SEP; in group IV (n = 16), precoated brackets and SEP were used for bonding. Bonding time, bracket failure rate, and adhesive remnant index (ARI) scores were measured. The mean orthodontic treatment time was 1.13 ± 0.18 years. One-way variance ANOVA was used to determine bonding time differences and the chi-square test was used to determine differences in bracket failure rates and ARI scores.

RESULTS

The bonding time was significantly lower for Groups III and IV, when compared to Groups I and II (p < 0.001). The bond failure rates were not different between the groups. Significant difference was observed between the procedures in relation to ARI scores (p < 0.001), which were higher in group IV.

CONCLUSIONS

Precoated brackets with SEP application significantly reduced chair time without compromising bracket failure rate.

CLINICAL RELEVANCE

Precoated brackets with SEP application can be safely used for bonding. Regarding the mode of failure, this group can be thought as favorable with a reduced risk of enamel tear.

In vitro analysis of shear bond strength and adhesive remnant index of different metal brackets

Introduction:

There is a great variety of orthodontic brackets in the Brazilian market, and constantly evaluating them is critical for professionals to know their properties, so as to be able to choose which product best suits their clinical practice.

Objectives:

To evaluate the bond strength and the adhesive remnant index (ARI) of different brands of metal brackets.

Material and Methods:

A total of 105 bovine incisors were used, and brackets of different brands were bonded to teeth. Seven different bracket brands were tested (MorelliTM, American OrthodonticsTM, TP OrthodonticsTM, Abzil-3MTM, OrthometricTM, TecnidentTM and UNIDENTM). Twenty-four hours after bonding, shear bond strength test was performed; and after debonding, the ARI was determined by using an optical microscope at a 10-fold increase.

Results:

Mean shear bond strength values ranged from 3.845 ± 3.997 (MorelliTM) to 9.871 ± 5.106 MPa (TecnidentTM). The majority of the ARI index scores was 0 and 1.

Conclusion:

Among the evaluated brackets, the one with the lowest mean shear bond strength values was MorelliTM. General evaluation of groups indicated that a greater number of bond failure occurred at the enamel/adhesive interface.

Orthodontic bonding with and without primer: a randomized controlled trial

OBJECTIVE

To evaluate the incidence of failure of brackets bonded with and without primer.

DESIGN

A single-operator, cross-mouth, randomized controlled trial (RCT).

SETTING

The Orthodontic Department at the Postgraduate Dental Education Centre, Örebro, Sweden.

ETHICAL APPROVAL

Ethical approval was granted by the Regional Ethical Review Board, Uppsala, Sweden.

PROTOCOL

The protocol was not published before trial commencement.

SUBJECTS AND METHODS

Fifty consecutive patients requiring bimaxillary orthodontic treatment with fixed appliances and with an equal number of teeth on each side of the dental arch, were included in this RCT. A cross-mouth methodology was applied. In each patient, two diagonal quadrants (i.e. upper right and lower left, or vice versa) were randomly assigned to the primer group (control group) and the contralateral diagonal quadrants to the non-primer group (experimental group). The randomization process was as follows: A computer-manufactured block-randomization list was acquired and stored with a research secretary at the Postgraduate Dental Education Centre. Each time a patient gave consent, the secretary was contacted by e-mail, and information about which quadrants were to be bonded with and without primer was obtained. All incidents of bracket failure and debonding noted in patient records during the 2012-14 observation period were compiled by the other co-author, whom was blinded to the study and did not perform any orthodontic treatment on the study patients.

MAIN OUTCOME MEASURES

Number of bracket failures over 18 months.

RESULTS

Failure rate without primer was 5.5 per cent and with primer 3.1 per cent; P = 0.063, odds ratio (OR) 1.89 [95% confidence interval (CI) 0.97-3.68] in the adjusted model. Younger ages (10-13 years), boys, and mandible were significantly associated with higher failure rates. Interaction tests indicated that younger patients had significantly higher failure rates without (12.1 per cent) than with primer (4.1 per cent), P < 0.001, OR 3.51 (95% CI 1.93-6.38) in the adjusted model. No failure rate differences between study settings were found for older patients (14-18 years).

LIMITATIONS

The difference between two groups was powered at 5 per cent. Some clinicians may consider a difference less than 5 per cent clinically significant.

CONCLUSION

Bonding Victory Series™ brackets with Transbond™ XT with or without Transbond™ MIP primer seems overall to work equally well in a clinical setting, except in younger children where lower failure rate was found in the primer setting.