Attitudes of orthodontists and laypersons towards tooth extractions and additional anchorage devices
Changsiripun and Phusantisampan Progress in Orthodontics
Attitudes of orthodontists and laypersons towards tooth extractions and additional anchorage devices
Chidsanu Changsiripun 0
0 Department of Orthodontics, Faculty of Dentistry, Chulalongkorn University , Henri-Dunant Road, Wangmai, Patumwan, Bangkok 10330 , Thailand
Background: This study investigated the attitudes of orthodontists and laypersons towards the choice of extracting second premolars, rather than first premolars, based on tooth condition and the use of additional anchorage devices. Methods: Questionnaires were sent to two groups: 324 orthodontists who were members of the Thai Association of Orthodontists, and 100 randomly selected Thai laypersons aged above 20 years and who were unrelated to the field of dentistry. Descriptive and chi-square statistics were used to analyze the data. Results: Questionnaires were returned by 142 orthodontists (43.8%) and completed by 100 laypersons. The larger the size of the caries lesion in the maxillary second premolar was found, the more orthodontists and laypersons both chose to extract a carious maxillary second premolar instead of a healthy maxillary first premolar. For orthodontists, the use of mini-implant anchorage was significantly related to their extraction decision. Orthodontists who were familiar with mini-implants usage would choose to extract the second premolar at a lower size of extent of caries. Besides, when larger sizes of caries lesions in maxillary second premolars were considered, laypersons tended to have greater acceptance of the use of additional anchorage devices in order to keep the healthy maxillary first premolar. Conclusions: In this study, tooth condition and the use of anchorage devices are currently the main considerations by both orthodontists and laypersons when selecting the teeth to be extracted for orthodontic treatment.
Extraction; Tooth condition; Anchorage devices; Orthodontists; Laypersons
One of the most common dental problems bringing
patients to see an orthodontist is anterior crowding and
]. One of the treatment options to create
space for solving this tooth size-arch length discrepancy
is tooth extraction, which allows the remaining teeth to
be moved into perfect alignment. Although the tooth
misalignment problem occurs within the anterior esthetic
zone, these anterior teeth should not be removed because
of their specific shapes and esthetic impact. Thus,
orthodontists typically choose to extract the first or
second premolar because of their lower impact on
esthetics and masticatory function compared to anterior
teeth and molars. Being close to the problem area, the first
premolar is the first choice for removal, compared with
the second premolar, because it is then simpler to close
the space created. In addition, keeping the second
premolar helps control the anchorage required to relieve the
anterior crowding. Therefore, most orthodontists would
choose to remove the first premolar to correct anterior
protrusion or crowding and to meet two of the goals of
orthodontic treatment, i.e., minimizing treatment time
and minimizing the distance the teeth must be moved [
Mini-implants play an important role in modern
orthodontic treatment planning as they can be the absolute
anchorage control [
]. Consequently, extracting the closest
tooth to the problem area may no longer be the best choice
for all moderate to severe crowding patients. Instead, the
concern seemed to shift to the long-term prognosis for the
tooth when selecting extraction sites in orthodontic
treatment. However, up to date, we still cannot find enough
studies which support this assumption.
Orthodontic treatment is considered to be a long
continuous process, compared with other dental treatments,
and patient compliance is essential for treatment success.
From personal experiences, it has been found that patients
who understand their condition and accept the proposed
treatment plan are more compliant. Therefore, studying the
attitude of laypersons regarding their preference of which
tooth to remove might be meaningful for orthodontic
treatment planning. However, currently, there are no
data regarding patients’ attitudes about this choice.
Previous investigations on tooth extraction for orthodontic
reasons evaluated whether first or second premolar
extraction decreased facial dimension [
dimensional changes measured from cephalometric analysis
], affected the soft tissue of upper lip areas [
allowed third molar eruption [
]. However, there are no
studies concerning the relative condition of the first
and second premolars when deciding which one to
extract. It was reported that the second premolars are more
vulnerable to caries attack than the first premolars with a
ratio of 1.6:1 [
]. Thus, the present study was undertaken
to answer the question as to how severe dental caries in
maxillary second premolar would make orthodontists and
laypersons choose to extract the maxillary second
premolar, instead of a healthy maxillary first premolar, in a
Class I Angle relationship with anterior crowding or
protrusion. The underlying assumption was that the case
had been analyzed and it had been decided to extract four
bicuspids with the need for maximum anchorage in the
A modified version of the Mount and Hume [
Classification System was used in our self-administered
questionnaires as a measure of the size of the caries lesion.
This questionnaire divided the size of lesions into seven
levels, from 0 to 6 (Table 1). We developed our own
questionnaires based on this classification, which comprised
two main parts for both orthodontists and laypersons to
Part I: general information of respondent such as
gender, age, educational degree, and orthodontic work
Part II: attitudes concerning removal of the maxillary
second premolar, rather than the maxillary first
premolar, according to the scenario described above and
attitudes towards the use of anchorage devices.
The study population was divided into two groups. The
first group was composed of all 324 active members of
the Thai Association of Orthodontists. The second
group included 100 Thai laypersons above 20 years old,
who would like to receive orthodontic treatment at the
orthodontic clinic, Faculty of Dentistry, Chulalongkorn
University, and were not related to the field of dentistry.
An identical patient education video was shown to all
potential orthodontic patients before they filled a
Statistical analyses were performed by descriptive and
chi-square analysis with SPSS software version 17.00
(SPSS Inc., Chicago, IL, USA). Statistical significance
was determined at P < 0.05.
Questionnaires were returned by 142 orthodontists (a
response rate of approximately 43.8%) and a hundred
laypersons were randomly surveyed individually. Some
returned questionnaires were incomplete, hence the
discrepancy in response numbers between individual items.
The orthodontists’ demographic details are displayed in
Table 2. The respondents were predominantly female
(68.3%), almost half were 31–40 years old (46.5%) and
Exposed pulp caries with extensive loss of enamel and dentine. Root canal treatment followed by crown restoration
is necessary in order to maintain the tooth.
approximately one third (31.7%) had up to 5 years’
experience as an orthodontist.
The demographics of laypersons are shown in Table 3.
More than half of the respondents were female (61%),
approximately two thirds were less than 30 years old
(76%), and the majority (80%) had a bachelor’s degree as
their highest level of education.
Attitudes towards caries extent
Regarding the scenario in the questionnaire, there were
three orthodontists and three laypersons who never
choose to extract the maxillary second premolar instead
of the maxillary first premolar, no matter what size of
the caries lesion in the second premolar. The responses
of the remaining respondents to items inquiring about
tooth condition are found in Fig. 1. It was found that the
larger the size of the caries lesion in the maxillary second
premolar, the more both orthodontists and laypersons
chose to extract the maxillary second premolar rather
than the maxillary first premolar. The greatest percentage
of respondents in both groups, orthodontists and
laypersons at 48.9 and 27.8%, respectively, chose the fourth size
of caries lesion as the minimum to confirm removal of the
maxillary second premolar rather than the maxillary first
premolar. The lowest minimum lesion size chosen by
orthodontists was 3 (10.8%), while that of laypersons was
Attitudes towards factors that influence an extraction decision
Responses to the items enquiring about the factors
influencing the respondents’ extraction decision are given in
Fig. 2. More than half of the respondents in both groups
(orthodontists, 51.5%; laypersons, 63.5%) agreed that
tooth condition was the main factor in making the
decision to remove the second premolar rather than the first
premolar. The second most important factor for
orthodontists was the total distance to move the anterior
teeth (20.6%). Although space closure was not important
to laypersons, the orthodontist’s opinion on which tooth
to remove had a greater influence (15.6%). Expense
was considered as the third most significant factor in
laypersons’ decisions (7.3%), while only 0.7% of
orthodontists took this into account.
Attitudes towards treatment plan discussion
Almost all orthodontists agreed with discussing the
treatment plan with patients, including which tooth to
remove (94.2%), while 5.1% finalized the treatment plan
themselves. 0.7% of responses were excluded as the
treatment plan was not discussed with the patient. For
laypersons, three quarters of patients agreed that it was
necessary to discuss the treatment plan with the
orthodontist, whereas some patients wanted to know about
the treatment plan; however, the final decision depended
on the orthodontist’s opinion (25%).
Orthodontists’ attitudes towards mini-implant usage and
More than half of the orthodontists’ based their decision
to extract the maxillary first or second premolar on the
anchorage situation (65.5%) while the remainder said it
had no effect.
Responses to items enquiring about orthodontists’ usage
of mini-implant anchorage are presented in Table 4.
Almost half of the respondents (45.3%) always placed
mini-implants themselves; one third sometimes did
(31.7%), while slightly less than one fifth (18.7%) had
never placed a mini-implant. Less than 5% had never
used a mini-implant as the absolute anchorage.
Chi-square analysis indicated that there was no
significant association between orthodontists’ ages and choice of
lesion size indicating extraction or between their working
experience and such choice. However, the lesion size was
significantly related to the orthodontists’ familiarity with
the use of mini-implant anchorage (MIA) (P = 0.04,
gamma = −0.3). Thus, orthodontists who used
miniimplants would choose to extract the maxillary second
premolar at a smaller lesion size, compared with those
who were less familiar.
Laypersons’ attitudes towards the use of anchorage
Responses to items enquiring about the use of different
anchorage devices chosen by laypersons are shown in
Fig. 3. If the maxillary second premolar was extracted
rather than the maxillary first premolar, additional anchorage
devices, such as a transpalatal arch (TPA), headgear, or
mini-implant, need to be installed. Patients were asked to
decide if they still wanted to remove the maxillary second
premolar when aware of this treatment requirement. When
they chose to keep the healthy maxillary first premolar, all
the laypersons agreed to wear the additional devices at
every size of caries lesion on the maxillary second premolar.
The larger the lesion, the more laypersons agreed to
wear additional devices. A TPA was the most acceptable,
followed by a mini-implant, and the least popular choice
was headgear at every caries lesion size.
Most of the chief complaints which prompt the patient
to seek orthodontic treatment in any populations are either
incisor protrusion or crowding [
]. The presence of
these clinical problems, even with a Class I molar
relationship, had influenced the extraction sequence decision, and
the choice of particular extraction sequences seems to have
been based largely on clinical opinion [
]. There have
been a number of previous studies demonstrating that
premolars are the most commonly extracted teeth for
orthodontic purposes due to their location between anterior
and posterior segments [
]. When comparing first and
second premolars, the first premolars are more often
extracted because of their position, being located nearer to the
problem site. Therefore, it is easier for anchorage control in
solving the patient’s chief complaint . On the other hand,
when second premolars are extracted, the posterior teeth
could be expected to move more forward than after a first
premolar extraction, leaving inadequate remaining space for
the relief of crowding and the retraction of anterior teeth
]. This is the reason why, in the past, orthodontists
almost always chose to extract the first premolars and keep
the second premolars, even though the second premolars
might be in far worse condition than the first premolar.
However, this was not found to be the case in the
present study. We found that most orthodontists and
laypersons set tooth condition as the most important
factor above others: for example, space closure, treatment
time, or expense, when deciding which tooth to remove.
Our study demonstrated that a number of orthodontists
and laypersons choosing maxillary second premolar
removal instead of healthy maxillary first premolar removal
increased for larger lesion sizes. That might be because
most laypersons who participate in this study are well
educated; 80% of them having a bachelor’s degree. They
prefer to keep a healthy tooth rather than a carious
tooth, even though they are informed of the requirement for
the additional anchorage device. Otherwise, anterior tooth
retraction or alignment of the teeth might not be optimal.
In part of the orthodontists’ opinion, we found that their
decision was significantly related to the familiarity with the use
of MIA. Orthodontists who typically placed mini-implants
themselves were likely to decide to remove the second
premolar with a smaller lesion compared with those who were
not familiar with mini-implant usage. This finding supported
the idea of MIA causing a paradigm shift in the orthodontic
world by not only making an unpredictable movement
possible, such as retraction of the whole maxillary dentition in
Class II division 1 malocclusions to achieve a Class I canine
and molar relationship without extraction [
], intrusion of
the entire maxillary dentition to correct gummy smile [
and intrusion of the upper posterior region to correct
anterior open bite [
], but also its impact on orthodontists’
decision towards extraction choice.
It is well known that closure of the premolar extraction
sites occurs by retraction of anterior segments, mesial
movement of posterior segments, or both. Maximum
anchorage is indicated to prevent mesial movement of the
posterior segments. One cephalometric study has shown
that greater mean maxillary incisor retraction was found in
the maxillary first premolar extraction group than in the
maxillary second premolar group [
]. Therefore, patients
also need to consider the additional anchorage requirement
when choosing to remove the maxillary second premolar,
in order to use the extraction space in a similar way to that
when extracting the maxillary first premolar. In the past,
headgear has been used as a standard maximum anchorage
system. However, it is almost always rejected by patients
because of social and esthetic concerns [
]. The present
study also showed that the larger the size of the caries
lesion, the higher the percentage of laypersons who
accepted wearing an anchorage device, including headgear.
This part of our result revealed the preference of laypersons
in the twenty-first century towards the type of additional
anchorage devices. Although a TPA was found to be the
most popular choice, unfortunately, it was reported to be
associated with anchorage loss during retraction of maxillary
anterior teeth [
]. MIA, which was as effective as headgear
with the non-compliance approach [
], is preferred by
patients to the alternative approaches available.
To our knowledge, the present work was the first
study investigating attitudes of laypersons towards their
decision of tooth extraction. Nowadays, there is a growing
awareness of conflict between orthodontists and patients
]. We believe that a greater communication before
starting the treatment is needed which will lead to improved
relationships and to a lessening of misunderstanding. Our
data supported this assumption by showing that both
groups of respondents agreed that it is necessary to discuss
the treatment plan together, particularly concerning tooth
removal. Therefore, our results are not only helpful in the
process of treatment planning between orthodontists and
orthodontic patients but also could be useful for general
practitioners by preventing unnecessary treatment on a
severely carious second premolar if the patient intends to
receive orthodontic treatment in the near future.
Nevertheless, some limitations in this study should be
noted. First, the response rate from orthodontists was
quite low (43.8%), although the number was almost
similar to other studies using the same method in the same
]. In the matter of gender, the
predominantly female sample of orthodontists (68.3%) could be
representative of the true population (64.8% female) [
Second, the data acquired in this study towards extraction
decision was based on one particular situation, which was
to decide between maxillary first or second premolar
extraction in a Class I Angle classification with anterior
crowding or protrusion with the need of maximum
anchorage in the upper arch. Our data showed that most of
orthodontists’ extraction decision (65.5%) was influenced
by how to manage the anchorage situation: maximum,
moderate, or minimum. Thus, we decided to create the
questionnaire by focusing only on a maximum anchorage
situation for the reasons of eliminating this confounding
factor and reducing the complications. Different results
might also be found if it was the situation in the lower
arch, as every orthodontist knows the differences in
anchorage control between in the maxilla and the mandible.
Therefore, this set of data should be applied with caution,
and further study is required with the series of
questionnaire including several types of anchorage in both arches.
Tooth condition and anchorage devices are currently the
main considerations when selecting which tooth to
extract in orthodontic treatment for both orthodontists
and laypersons in the present study.
The authors are grateful to Professor Martin Tyas for his constructive
comments in review of this manuscript. We also would like to thank Dr.
Chompunuch Tiyawongmana and Dr. Hathaiwan Ngamsukonthapusit for
their help in the process of collecting questionnaires.
CC contributed to the study conception and design, performed the literary
research, participated in the interpretation of the data, and wrote the
manuscript. PP carried out the data collection, data analysis, and wrote part
of the paper. Both authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Ethics approval and consent to participate
This study was conducted in full accordance with the World Medical Association
Declaration of Helsinki. Ethics approval was received from the Faculty of Dentistry,
Chulalongkorn University Human Research Ethics Committee and consent was
implied by all participants who completed the survey.
Springer Nature remains neutral with regard to jurisdictional claims in
published maps and institutional affiliations.
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