Comparison of the Brackets Bonded With Bulk Fill Composite and Conventional Composite in Patients Undergoing Fixed Orthodontic Treatment - A Split-mouth Randomized Controlled Trial
Phase: EARLY_PHASE1
Conditions: Survival Rate of Bonded Brackets
Sponsor: Rizwan Khalil

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Document Date: 03-Aug-2024 
TITLE: Comparison of the Brackets Bonded with Bulk Fill Composite and Conventional 
Composite in Patients Undergoing Fixed Orthodontic Treatment – A Split-mouth 
Randomized Controlled Trial 
INTRODUCTION: 
Fixed orthodontic treatment aims at correcting malocclusion and improving dental aesthetics.  It 
often entails bonding orthodontic brackets to the teeth.1  The success of fixed orthodontic 
treatment is highly dependent upon the durable and reliable bond between brackets and the tooth 
surfaces.2,3  Bracket bond failure remains a significant concern, leading to compromised 
treatment outcomes.4  Bond failure can occur due to various factors, such as inadequate bonding 
strength, poor oral hygiene and accumulation of dental plaque around the brackets.5  Bond failure 
not only compromises treatment effectiveness but also leads to increased chair side time, 
treatment interruptions and additional costs for patients.6   
To date, light cure conventional composite resins have been widely used for bracket bonding.7,8  
Mechanical properties of the adhesive resins and resin composites, such as the flexural modulus, 
compressive strength, and tensile strength, depends on the degree of cure or monomer 
conversion of the adhesive resin by conventional curing method with light directed from the 
sides of the bracket.9  However, the convexity of the labial tooth surface and the bracket material 
hinder or obstruct direct light propagation resulting in incomplete polymerization of the adhesive 
at the center of the bracket.8,9  Light cure conventional composite resin undergoes polymerization 
shrinkage during the curing process.10  This shrinkage can generate stress at the bracket-tooth 
interface, potentially leading to debonding or adhesive failure over time.  However, 
advancements in dental materials have introduced bulk fill composites as an alternative option.11   
Bulk fill composites are formulated to improve light penetration and depth of cure.12  This 
ensures that the composite is adequately polymerized even at the center of the bracket.  Bulk fill 
composites often exhibit lower polymerization shrinkage stress compared to light cure 
conventional composites.13  The improved formulation and composition help to minimize the 
contraction forces during polymerization, reducing the likelihood of adhesive failure of the 
brackets.14   

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Bracket bond failure is a critical parameter to assess the adhesive strength between brackets and 
tooth surfaces.15,16  In addition to bond failure, dental plaque accumulation and gingival health 
are important aspects to consider during fixed orthodontic treatment.17  Plaque accumulation 
around brackets and along the gingival margins can lead to an increased risk of dental caries, 
enamel demineralization and gingivitis.18  Therefore, it is crucial to evaluate the impact of 
different bracket bonding materials on plaque accumulation and gingival health.   
To the best of our knowledge, there has been no previous study on this subject.  Therefore, the 
idea of comparing brackets bonded with bulk fill composite and light cure conventional 
composite in a split-mouth randomized controlled trial intrigued our attention.  This study will 
address a relevant aspect of fixed orthodontic treatment, bracket bonding and compare two 
adhesive materials that have the potential to impact the efficiency and clinical outcomes of fixed 
orthodontic procedures.   
RATIONALE: 
Bulk fill composites have gained popularity as alternative bracket bonding materials due to their 
potential advantages over light cure conventional composites.19  Bulk fill composites have the 
benefit of increased depth of curing and less polymerization shrinkage.20  However, there is 
limited research comparing the clinical performance of these materials in terms of bracket bond 
failure, dental plaque accumulation and gingival health.  Bond strength of orthodontic brackets 
on bulk fill composite surfaces was not found adequate.21  Understanding the performance of 
different adhesive materials used in bracket bonding is crucial for orthodontists to make 
informed decisions regarding material selection, optimizing treatment outcomes and ensuring 
patients' oral health.  By assessing bracket bond failure, dental plaque accumulation and gingival 
health, this study aims to provide valuable insights into the clinical performance of different 
adhesive materials, contributing to evidence-based practices in fixed orthodontic treatment.   
OBJECTIVE: 
The primary objective of this study is to compare the survival rate (days) of orthodontic bracket 
bond to the tooth, and the secondary objective is to compare the dental plaque accumulation and 
gingival health using plaque index and gingival index respectively between brackets bonded with 

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bulk fill composite and light cure conventional composite in patients undergoing fixed 
orthodontic treatment over a period of three months. 
HYPOTHESIS: 
Null Hypothesis: 
There is no significant difference in the survival rate, dental plaque accumulation and gingival 
health between brackets bonded with bulk fill composite and light cure conventional composite 
in patients undergoing fixed orthodontic treatment.   
Alternate Hypothesis:  
There is a significant difference in the survival rate, dental plaque accumulation and gingival 
health between brackets bonded with bulk fill composite and light cure conventional composite 
in patients undergoing fixed orthodontic treatment.   
OPERATIONAL DEFINITIONS: 
Survival rate of bonded brackets:22 (Annexure A)  
A bracket survived how many days in mouth without detaching from the tooth surface.   
Bulk Fill Composite:23 (Annexure B) 
In this study, 3M™ Filtek™ One Bulk Fill restorative will used as intervention. 
Light Cure Conventional Composite:23 (Annexure C) 
In this study, 3M Unitek Transbond XT - Light Cure Bracket Bonding adhesive will be used as 
control. 
Plaque Index:24 (Annexure D) 
Plaque index is a grading system used to assess the plaque accumulation around the bonded 
brackets and gingival margins.  It consists of four grades including, Grade 0, 1, 2 and 3.  The 
increase in grade indicates the increased amount of plaque along the gingiva.   
 
 

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Gingival Index:24 (Annexure E) 
Gingival index is a grading system that is used to assess the health of the gingiva.  It consists of 
four grades including, Grade 0, 1, 2 and 3.  The increase in grade indicates the compromised 
health of gingiva.   
Split-mouth Technique:25 
A randomized controlled trial in which intervention and control are randomly allocated to the 
different quadrants in the oral cavity.  In our study, bulk fill composite and light cure 
conventional composite will be randomly allocated to the right and left quadrants of maxillary 
and mandibular arches. 
MATERIAL & METHODS: 
Study Design: A split-mouth randomized controlled single-centered trial 
Settings: Dental clinics, Department of surgery, Aga Khan University Hospital, Karachi, 
Pakistan 
Recruitment Time Duration: 01-01-2025 to 30-03-2025 
Study Duration: One year after ethical review committee (ERC) approval 
Sampling Technique: Non-probability consecutive sampling 
SAMPLE SIZE:  
The sample size was calculated using standard estimate where n = 8(CV)2 /(PC)2 [1+(1-PC)2], 
where PC is the proportionate change in means (PC = (μ0 −μ1)/μ0) and CV is the coefficient of 
variation (CV = σ0/μ0 = σ1/μ1).  The study required a minimum sample size of 53 (N) patients.  
With an inflation of 10% for an estimated loss to follow up/non-response rate, we will be 
including 58 (N) participants in this study to achieve 80% power and to detect at least a 20% 
change in mean bracket survival rates of 176.75 ± 76.26 days and 197.19 ± 81.78 days with 
conventional composite and RMGIC, respectively and 40% or less change in coefficient of 
variation at two sided 5% level of significance.  The sample size was calculated by using the 
findings of Qabool et al.26  So, we will have 232 quadrants in total.  Bulk fill composite will be 
used for bonding brackets on the teeth surfaces in half quadrants to either right side or left side 
by using randomization.   

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SAMPLE SELECTION:  
Inclusion Criteria: 
 
Patients aged between 13 - 40 years 
 
Patients undergoing fixed orthodontic treatment  
 
Patients with good oral hygiene, with grade 1 or below on plaque and gingival indices  
 
All patients who will sign the informed consent/assent form  
Exclusion Criteria:  
 
Patients with enamel surface defects 
 
Patients with any periodontal disease i.e. gingivitis or periodontitis 
 
Patients with any systemic diseases i.e. diabetes and hypertension 
 
Pregnant or nursing females 
 
Patients with craniofacial syndromes 
 
Subjects with a previous history of orthodontic or orthopedic treatment 
STUDY GROUPS: 
The patients will be screened using the inclusion and exclusion criteria by the co-investigator.  
Bracket bond failure and clinical measurements (plaque accumulation and gingival health) will 
be recorded at four intervals (T0, T1, T2 and T3).   
Group A (Intervention): Bulk fill composite.  
Group B (Control): Light cure conventional composite.  
The participants will receive routine instructions for oral hygiene maintenance and care of the 
appliance verbally. 
DATA COLLECTION PROCEDURE: 
After obtaining approval from the Ethical Review Committee and taking informed assent and 
informed consent from the child and parents respectively, (Annexure F, G and H), patients 
fulfilling the study selection criteria will be recruited in the study as participants.  Patients 
visiting the orthodontic clinic at the Aga Khan University Hospital Karachi will be included in 

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this study.  Detailed information regarding the study will be provided to the participants and they 
will be given the choice to either accept or refuse their inclusion in the study.  Bulk fill 
composite and light cure conventional composite will be used to bond the brackets in the study 
participants undergoing orthodontic treatment (Annexure B and C).  Bulk fill composite and 
light cure conventional composite will be randomly allocated to the right and left quadrants of 
maxillary and mandibular arches.  Bracket bond failure and clinical measurements (plaque 
accumulation and gingival health) will be recorded at four intervals.  First, at the time of brackets 
bonding (T0), after one month (T1), two months (T2) and three months follwow-up (T3).  Data 
will be collected on an organized study proforma (Annexure I). 
Interim analysis will be run to ensure that there are no unexpected safety concerns associated 
with the intervention.  The analysis may help determine whether the intervention is effective in 
achieving its desired outcomes or if there are indications of potential success.  If the interim 
analysis will reveal overwhelming evidence of effectiveness or futility, the trial will be 
terminated early, saving time, money, and potential exposure to participants.   
Intention to treat analysis will be applied to maintain the benefits of randomization and avoid 
introducing bias due to non-adherence or dropouts. By analyzing participants as part of their 
original assigned group, the ITT analysis provides a more conservative estimate of treatment 
effects, reflecting real-world scenarios where not everyone perfectly adheres to the assigned 
treatment. 
Randomization:  
Block randomization will be used to determine which side of teeth (right or left side quadrants) 
the bulk-fill composite will be used to bond the brackets in each participant.  This will be 
controlled by a research faculty member of the Section of Dentistry assigned to the research by 
the Clinical Trials Unit AKUH. 
Random Sequence Generation:  
In this two-armed study, fifteen blocks each with a block size of four with any of the following 
six-possible allocation sequences for two treatment arms will be generated.  
(1) AABB, (2) BBAA, (3) ABAB, (4) BABA, (5) ABBA, (6) BAAB 

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The blocks to be utilized and their order will be determined by the research Faculty member 
using sealed envelopeTM online software.28 
Allocation Sequence Concealment:  
The treatment allocation pattern determined against each participant’s ID (01-58, in ascending 
order) by the research faculty member, will be printed individually on paper.  These papers will 
be sealed in an opaque envelope with the participants’ ID mentioned over the envelope by a team 
member independent of the trial.  
Enrollment:  
After obtaining approval from the ERC (AKUH), each participant fulfilling the inclusion criteria 
for the study and consenting to participate in the trial will be assigned a participant ID.  
Implementation:  
During the recruitment of the participants in the trial,  the sealed envelope for a participant ID 
will be opened to reveal the random sequence by the enrolling team member. 
Blinding:  
The study investigators, patients and assessors will not be blinded during the trial.  The patients 
will be recruited by the co-principal investigator.  All the measurements will be recorded by the 
co-investigator on the study proforma (Annexure E). 
POSSIBLE RISKS OR BENEFITS:  
Orthodontic wire might shift more to one side due to bracket bond failure and poke the patient.  
This will be managed by giving instructions to patients that if this happens then you will have to 
report immediately to the outpatient orthodontic clinic.  There are no other serious adverse 
effects.  In case any serious adverse event happens ERC, CTU and the sponsors will be 
informed.   
 
 

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DATA ANALYSIS:  
Data will be entered and analyzed in SPSS for Windows (version 23.0, SPSS Inc. Chicago).  
Shapiro-Wilk test will be used to check the normality of the data.  Descriptive statistics, such as 
means and standard deviations for normally distributed or median and interquartile range (IQR) 
for non-normally distributed data will be reported for all baseline clinical factors.  Paired t-
test/Wilcoxon test will be used for the pairwise comparison.  Gingival index and plaque index 
will be analyzed as quantitative variables.  Gingival and Periodontal health scores will be 
assessed between the two groups using Paired t test / Wilcoxin sign rank test.  The rate of bracket 
survival and total number of bracket breakages in the two groups will be assessed by Cox 
proportional hazards model, with stratification on the matched pairs.  A p-value < 0.05 at 95% 
confidence interval will be considered as statistically significant. 
ETHICAL CONSIDERATION: 
This study will be carried out as per the guidelines of the World Medical Association’s 
Declaration of Helsinki27 and the principles of Good Clinical Practice (GCP).  Any modifications 
in the protocol will be re-submitted to the ERC.  The study will be conducted in compliance with 
regulations and a copy of the final study protocol will be submitted to ERC.  All the recorded 
data of patients will remain confidential.  Access will be provided to no one except the 
investigators.  Participants’ names and identities will remain undisclosed; however, data may be 
seen by ERC or any local regulatory body.  Data will be saved for 10 years as per GCP and 
institutional guidelines.   
FINANCE: 
The Aga Khan University Hospital, Karachi (Department of Surgery).   
PUBLICATION POLICY/PLAN: 
For publication the data will be utilized and it could be presented in either national or worldwide 
forums.   
 
 

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DATA CONFIDENTIALITY:  
All the recoreded data of patients will remain confidential.  Access will be provided to no one 
except the investigators.  Participants’ names and identities will remain undisclosed; however, 
data may be seen by ERC or any local regulatory body.  Data will be saved for 25 years as per 
GCP and institutional guidelines.  

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Annexure A: Bond failure22 
 
 
 

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Annexure B: Bulk fill composite resin23 
 
 
Storage: Stored at room temperature in cabinets of dental procedure rooms where other 
materials are stored and protected from humidity and sunlight.   
Usage: Steps for light -cure composite bonding are: 
a. Prepare teeth with oil-free pumice, and rinse thoroughly for 15 seconds with water.  
b. Air dry tooth surface for 5 seconds until dry field is maintained and isolate with cotton 
rolls.  
c. Etch enamel surface with 37% phosphoric acid for 15 seconds. 
d. Rinse the etched surface for 20 seconds to remove the acid and precipitates that might 
have formed during the etching procedure. 
e. Thoroughly dry etched surface with moisture free air.  Tooth surface should appear frosty 
white; if not then re-etch for 5 seconds.    
f. Brush thin uniform amount of primer on every tooth surface.   
g. Apply a small amount of adhesive paste onto bracket base and position the bracket on 
tooth surface.  
h. After accurately placing bracket on tooth surface, apply visible blue light for 30 seconds 
on center of bracket.   
 

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Annexure C: Light cure conventional composite resin23 
 
 
Storage: Stored at room temperature and protected from humidity.   
Usage: Steps for light -cure composite bonding are: 
a. Prepare teeth with oil-free pumice, and rinse thoroughly for 15 seconds with water.  
b. Air dry tooth surface for 5 seconds until dry field is maintained and isolate with cotton 
rolls.  
c. Etch enamel surface with 37% phosphoric acid for 15 seconds. 
d. Rinse the etched surface for 20 seconds to remove the acid and precipitates that might 
have formed during the etching procedure. 
e. Thoroughly dry etched surface with moisture free air.  Tooth surface should appear frosty 
white; if not then re-etch for 5 seconds.    
f. Brush thin uniform amount of primer on every tooth surface.   
g. Apply a small amount of adhesive paste onto bracket base and position the bracket on 
tooth surface.  
h. After accurately placing bracket on tooth surface, apply visible blue light for 30 seconds 
on center of bracket.   
 
 
 

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Annexure D: Plaque Index24 
 
0 
No plaque 
1 
Thin plaque layer at the gingival margin, only detectable by scraping 
with a probe 
2 
Moderate layer of plaque along the gingival margin; interdental 
spaces free, but plaque is visible to the naked eye 
3 
Abundant plaque along the gingival margin; interdental spaces filled 
with plaque 
 
 
 

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Annexure E: Gingival Index24 
 
0 
Normal gingiva; no inflammation; no discoloration (erythema); no 
bleeding 
1 
Mild inflammation; slight erythema; minimal superficial alterations; 
no bleeding 
2 
Moderate inflammation; erythema; bleeding on probing 
3 
Severe inflammation; severe erythema and swelling; tendency to 
spontaneous bleeding; possible ulceration