Adhesive Remnant Index for Type of Bond Failure Clinical Trial
Official title:
Is a Primer Needed for Orthodontic Bonding? A Multi-centre RCT
Orthodontic treatment is carried out by placing fixed attachments(brackets)on teeth with
wires which run through them and create tooth movement. These metal brackets are bonded
(glued) onto the tooth surface by a three step process. Firstly, a mild acid is used to
roughen the tooth surface, secondly a free flowing glue (composite primer) is used to fill
in the roughened pores and thirdly, the bracket is glued on to the tooth surface with a
'composite' material which sets hard by exposure to a high intensity light.The success of
this procedure is measured by bracket failure rates.
The literature review suggests that the scientific evidence is not clear to indicate whether
the use of a primer is absolutely essential to achieve acceptable bracket success rates in a
clinical environment.
The primary aim of the study is to find out if the rate of loss of orthodontic brackets is
clinically acceptable when they are glued onto the tooth surface without the use of a primer
as compared to brackets bonded with a primer over a 12 month study period. The investigators
will also investigate the Bonding time,Type of bracket bond failure,length of treatment and
Peer Assessment Rating scores (PAR)
This RCT will be undertaken on consented NHS patients in 3 hospitals in Yorkshire region by
multiple operators
The results from this study will help improve our knowledge of the best approach to bonding
metal brackets on teeth. If the bracket failure rate is similar in both groups, this would
indicate that the use of a primer is not always necessary. For patients, this would mean
lesser time required to place brackets at the start of orthodontic treatment. For clinicians
and NHS purchasers the outcome will influence cost effectiveness (as the primer is the most
expensive component in the bonding process) and provide a framework for future studies.
AIMS OF THE TRIAL The primary aim of the trial is to find out if clinically acceptable
bracket failure rates can be achieved when metal brackets (fixed brace attachments) are
glued (bonded) to teeth without the use of a primer as compared to brackets glued with a
conventional primer in adolescent and adult orthodontic patients over a 12 month study
period.
The other objectives are to determine if the gluing time per bracket is different between
the groups and the type of glue failure at bracket-tooth interface using Adhesive Remnant
Index. Length of treatment time and Peer Assessment Rating scores will also be analysed.
HYPOTHESES The null hypothesis for the primary outcome is - "there is no difference in the
bracket failure rates when metal brackets are bonded with primer as compared to those which
are bonded without a primer".
The null hypotheses for the secondary outcomes are - "there is no difference in the bonding
time per bracket and the type of bond failure using Adhesive Remnant Index between the
control and experimental group in this study.
METHOD OF INVESTIGATION
1. Sample population All patients referred to the Leeds Dental Institute/Seacroft
hospital/ St.Luke's hospital, Bradford who qualify for orthodontic treatment.
2. Setting Patients treated in a dental teaching hospital and district NHS hospital
setting
3. Operator characteristics All patients will be treated from the start until the end of
the study period by 6 operators of various experience (NHS specialist registrar at two
sites − Leeds Dental Institute and St.Luke's Hospital, orthodontic therapists (SLH) and
consultant orthodontists (SLH/LDI and Seacroft hospitals)
4. Study design A multicentre single-blinded randomised controlled clinical trial in a NHS
hospital setting. Individual patients will be allocated randomly to either the test or
control group.
5. Intervention Test group − Metal brackets will be bonded without a primer Control group
− Metal brackets will be bonded with primer
6. Methods to minimise bias - Randomisation and Blinding All consecutive patients who need
fixed appliance treatment will be taken off the waiting list and no attempt will be
made to match them for age, sex or malocclusion to ensure a representative sample,
except for the exclusion criteria. After informed consent is obtained, they will be
randomly allocated to either the control (with primer) or experimental (without primer)
group. This will be done by preparing opaque numbered sealed envelopes in blocks of 10
in advance by the supervisor (NH) using random number tables. The supervisor will
enroll the participants and assign them to their group using the sealed envelopes which
blinds the two operators and participants to the assignment before enrollment. Once the
envelopes are opened the blinding of the operators will be lost. The operators cannot
be blinded in this trial as the intervention administered to the test group cannot be
blinded. Treatment will be started on all patients within 3 months of the enrollment.
7. Agreed start and end points Upper and lower teeth will be bonded when appropriate. If
upper and lower teeth are bonded at separate visits, then the specific dates will be
considered as the start point. The follow up period will be for 12 months and the
incidence of first bracket loss will be recorded (i.e. event). Any subsequent bracket
loss will also be recorded. For patients who have no failures the bracket survival time
will be followed up until the end of fixed appliance treatment by the original or
subsequent operator (i.e. anybody involved in the follow−up of these patients after the
end of 12 month study period). In the event of repeated failures in the same patient or
in the same area, the data will be recorded and statistical analysis for clustering
will be appropriately selected.
8. Subject withdrawal criteria Any participant can voluntarily withdraw from the study at
any time without any compromise to the agreed and proposed treatment. Such a subject
will be accounted for during data and statistical analysis. The drop-out sample will
not be replaced during the trial. All data pertaining to first time bracket failure
will be recorded as agreed until the withdrawal date for an individual sample. The
follow up of such a patient will be for orthodontic treatment only and data pertaining
to the trial will not be recorded after a sample confirms a withdrawal.
9. Trial termination - reasons for abandoning the trial The trial will be terminated if
more than 50% of the brackets fail ( greater than 8 brackets per patient) in the
experimental group in at least three patients within the first review appointment (6
weeks). This is because such a high failure rate is clinically unacceptable for
continuation of routine orthodontic treatment in the experimental group.
10. Bracket Bonding procedure As the bracket failure rate for the control group has been
calculated from a previous study by Littlewood et al., a similar procedure to bond
brackets will be followed in this study to avoid intervention bias. All teeth will be
bonded including molar teeth. A pre−calibrated light curing unit will be used for
setting the glue hard as follows -
CONTROL GROUP
1. 30 second wash and 30 second dry using 3 in 1 syringe
2. 30 second treatment with 37% phosphoric acid gel
3. 30 second wash and 30 second dry using 3 in 1 syringe
4. Application of primer to acid treated enamel and air thinned.
5. Metal bracket placed at long axis point on the outer surface of the tooth
6. Light polymerisation; 30 seconds each on either side of each tooth
TEST GROUP
1. 30 second wash and 30 second dry using 3 in 1 syringe
2. 30 second treatment with 37% phosphoric acid gel
3. 30 second wash and 30 second dry using 3 in 1 syringe
4. Metal bracket placed at long axis point on the outer surface of the tooth
5. Light polymerisation; 30 seconds each on either side of each tooth
11. Type of data collected
The following data will be collected:
1. Bracket lost for the first time and subsequent failure with the respective tooth
notation
2. Date of bracket failure*
3. Tooth number
4. Whether a primer was used or not
5. Operator involved
6. Time taken from the first step of bonding procedure until the last bracket is placed in
each arch
7. Adhesive Remnant Index of debonding interface
8. Patient identification number
9. Length of treatment
10. Peer Assessment Rating score (PAR) *If a patient attends an appointment with a bracket
failure but the actual failure date cannot be accurately recalled by the patient, then
the date of first attendance with bracket failure will be noted.
12. Outcomes (primary and secondary)
1. Primary outcome - Bracket failure rate for test and control group
2. Secondary outcomes - Bonding time per bracket, Type of bond failure (using Adhesive
Remnant Index), length of treatment and PAR scores.
Summary of main issues -
1. PURPOSE AND DESIGN
Routinely orthodontic treatment is carried out by placing orthodontic brackets on teeth
and wires which run through them which help move teeth. These metal brackets are bonded
or glued onto the tooth surface by a three step process. Firstly, a mild acid is used
to roughen the tooth surface, secondly a free flowing glue (composite primer) is used
to fill in the roughened pores and thirdly, the bracket is glued on to the tooth
surface with a 'composite' material which sets hard by exposure to a high intensity
light. In routine studies, the success of this procedure is measured by bracket failure
rates.
The literature review revealed 7 studies which were relevant to bonding of orthodontic
brackets with and without use of primers. Out of these 5 were invitro experimental
studies, 1 was a retrospective study and 1 was a prospective non−randomised controlled
study. Most studies in this field have been lab based studies which have measured bond
strength and failure rates in extracted human teeth. The methodologies used have been
retrospective and lack robust study design to eliminate bias. This literature review
suggests that the scientific evidence is not clear to indicate whether the use of a
primer is absolutely essential to achieve acceptable bracket success/failure rates in a
clinical environment. A RCT was designed and carried out in Bradford/Leeds (see
previous reference number) which showed no statistical difference between the primer
and non primer groups. However, this was a single operator study who was an orthodontic
trainee. This study aims for a 'real world' effect by using multiple operators with
various degrees of orthodontic experience.
To summarise, arguably the evidence available from previous studies to either support
or refute the use of primer prior to bonding brackets in a clinical setting appears to
be weak. The main drawbacks of these studies were related to inconsistent study designs
and many of the conclusions may not be applicable for the following reasons -invitro
studies, use of chemically cured resins rather than light cured systems which are
currently used, different bracket systems, variation in bonding steps, use of flowable
composites which are not routinely used for bonding and lack of a prospective
randomized controlled study in a clinical setting. All these studies have concluded the
need for further research to investigate if clinically acceptable bond strength can be
achieved without the use of a primer. If this hypothesis is true, then bonding brackets
may become faster, efficient and cost effective. Therefore, a well designed randomized
controlled study could be justified to clarify if the use of a primer is essential
prior to bonding brackets.
The results from this randomised clinical trial will help improve our knowledge of the
best approach to bonding metal brackets on teeth. If the bracket failure rate is
similar in both groups, this suggests that the use of a primer is not always necessary
to gain sufficient bond strength in a clinical environment. From a patient's
perspective, this would mean lesser clinical time required to place brackets at start
of orthodontic treatment. For clinicians and NHS purchasers the outcome of the study
will influence clinical chair side time, cost effectiveness (as the primer is the most
expensive component in the bonding process) and provide a framework for future studies
in this field.
The trainee student will benefit from training in broad research methodology,
scientific critique, statistical concepts and experience in undertaking a randomised
clinical trial as a part of Masters project.
PROTOCOL/ QUALITY ASSURANCE The research will be undertaken as a part of routine
orthodontic care provided by a consultant led service in orthodontic departments in
Leeds Dental Hospital, St Lukes Hospital and Seacroft hospital. All the patients
recruited into the project will receive the same standard of quality orthodontic
treatment as provided if they did not choose to partake in the study. All the
procedures for orthodontic treatment at the Leeds Dental Institute/Bradford teaching
hospitals are quality assured by the Deanery/General Dental Council and Specialist
Advisory Committee (SAC) as part of an established three year training programme in
Orthodontics (this relates to the fact that one of the researchers will be an
orthodontic registrar on on a training pathway). The other clinicians are orthodontic
consultants and orthodontic therapists supervised by orthodontic therapists.
The research committee at Leeds Dental Institute consists of Clinical/Academic
Orthodontic Consultants from the region and are routinely involved in supervision of
MSc/DDS students regarding their research projects every year. This panel was asked to
review the protocol prior to submission and the members include independent reviewers
not involved in the study.
RECRUITMENT All consecutive patients who need fixed appliance therapy will be taken off
the NHS waiting list and no attempt will be made to match them for age, sex or
malocclusion to ensure a representative sample, except for the exclusion criteria.
After informed consent is obtained, they will be randomly allocated to either the
control (with Transbond primer) or experimental (without primer) group. This will be
done by pre paring opaque numbered sealed envelopes in blocks of 10 in advance by the
supervisor (NH) using random number tables. The supervisor will enroll the participants
and assign them to their group using the sealed envelopes which blinds the two
operators and participants to the assignment before enrollment. Once the envelopes are
opened the blinding of the operators will be lost. The operators cannot be blinded in
this trial as the intervention administered to the test group cannot be blinded.
Treatment will be started on all patients within 3 months of the enrollment.
INCLUSION / EXCLUSION Inclusion criteria •Patients requiring single or two arch fixed
appliance therapy (with no history of previous orthodontic treatment)including patients
requiring orthognathic surgery
•Willing to consent to participate in the trial
Exclusion criteria
- Patients with craniofacial anomalies
- Patients with several buccal restorations or congenital enamel defects
- Hypodontia cases (with more than one tooth missing in each quadrant)
CONSENT Children under 16 Routine orthodontic treatment is undertaken at about 12 years
of age onwards and a majority of patients requiring orthodontic treatment will be from
this age group on a NHS waiting list. These patients have to be included in the study
as any clinical relevance of the study will be applicable to patients in this age
group, in addition to adults. Appropriate informed consent with parental involvement is
routinely followed at the start of treatment for these patients as per NHS trust
policy.
Each participant will be given a patient information sheet outlining the objective,
details of the study and answer any frequently asked questions. The patient information
sheet will be drafted individually for both adults and children below 16 years of age.
The informed consent process will be done by the registrar treating the case or the
supervising consultant, usually at the next appointment so that enough time is given to
the patient if they choose to participate. All participants will be explained regarding
the research prior to consent. For participants below 16 years of age, the informed
consent process will involve the responsible parent who will sign the form in addition
to the child.
A minimum of 24 hours upto 6 weeks (until the next appointment) of time will usually be
available for the patient to think over the decision to participate. In routine
orthodontic treatment, usually the registrar/clinician will take treatment records at
the initial visit and give a patient information leaflet. Routinely any treatment
planning and consent is done at the subsequent appointment which is usually in a few
weeks under consultant supervision.
Any participant requiring language interpretation will be provided with a suitably
qualified interpreter, as per the NHS trust protocol. No participant will be excluded
on the basis of ethnic origin, language preferences, religion, sexual preference or
gender.
Any involvement of patients with significant learning disability or special needs
raises sensitive issues related to comprehension and consent. Although they will be not
excluded from participation if they wish to do so, these patients will be offered to
partake and the views of the person with parental authority will be considered.
RISKS, BURDEN AND BENEFITS Possibly, greater failure of brackets (fixed brace
attachments) in the experimental group which may need to be glued back on soon after.
These failures will not affect the treatment outcome in any way.
Possibly, extra visit to the department if brackets fail, so that they can be glued
back on. This may add on a few weeks of additional time to overall treatment, but will
not affect the treatment outcome in any way.
As per the drafted protocol for the trial " the trial will be terminated if more than
50 % of the brackets fail in the experimental group in at least three patients within
the first review appointment (6 weeks). This is because such a high failure rate is
clinically unacceptable for continuation of routine orthodontic treatment in the
experimental group " In such a situation all the participants will be informed in
writing regarding trial termination and all steps would be taken to ensure that routine
orthodontic treatment is continued as planned. In such cases all the brackets which
have been bonded as per the protocol for the experimental group will be replaced to
match the control group i.e. routine treatment.
CONFIDENTIALITY Each patient will have a patient identification number as per trust
policy and this will be quoted on all forms relevant to the study. No other
identifiable information will be available on the forms. All electronic data pertaining
to the study will be stored in computers within the NHS site and these systems are
subject to local NHS trust data protection policies and caldicott principles. No
external source will have access to this data. The data will be shared only within the
members of the research team for analysis purposes.
The data will be stored in NHS computers and will be protected as per the NHS trust
protocol under the Data Protection Act. The Chief investigator and members of the
research team will have access to the data
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Allocation: Randomized, Endpoint Classification: Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind (Outcomes Assessor), Primary Purpose: Treatment