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Long-term stability of orthodontic treatment results is problematic. Long-term or even lifelong retention with bonded retainers is being increasingly used among clinicians. Bonded retainers can provide an efficient and attractive method of retention, particularly because they require minimal compliance from patients. However, the use of bonded retainers is associated with relatively frequent complications, such as detachments of the adhesive layer or wire fractures, as well as unexpected complications with potentially severe consequences with associated periodontal and general health risks. It is imperative that the whole dental team are aware of these pitfalls and complications, and appreciate how to minimise and address these. Encourages balanced discussion among the dental team concerning long-term retention with bonded retainers, focusing on the possible complications associated with the use of bonded retainers.Discusses the factors influencing occurrence of complications and the potential negative effects on adjacent tissues as well as general health.Stresses the importance of monitoring bonded retainers by all members of the dental team and early interception of complications in order to prevent development of severe clinical consequences. Encourages balanced discussion among the dental team concerning long-term retention with bonded retainers, focusing on the possible complications associated with the use of bonded retainers. Discusses the factors influencing occurrence of complications and the potential negative effects on adjacent tissues as well as general health. Stresses the importance of monitoring bonded retainers by all members of the dental team and early interception of complications in order to prevent development of severe clinical consequences.
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Josef Kučera,*1"Simon"J."Littlewood2 and Ivo Marek3
The main goals of orthodontic treatment
are improve d aesthetics, occlusion and
stability. Achieving long-term stability of the
orthodontic treatment is a signicant challenge
for a number of reasons.1,2 e problem may
be in the denition of long-term stability itself.
If we are aiming to achieve an occlusal result
that is permanent and unchangeable forever,
then both clinicians and patients are likely
to be disappointed. Indeed, this reflects a
general natural tendency in nature for things
to become less organised with time due to the
laws of entropy within biological systems.
Post-treatment changes can arise due to
relapse, dened as the return of teeth towards
their original position,3 but can also relate to
normal age-related changes. Specically, there
is a natural tendency for shortening of the
arches in relation to length and depth, reduced
perimeter, decrease in intercanine width
and subsequently an increase in crowding,
especi ally in the mandibular anterior
segment.4,5,6,7 However, patients and even
clinicians are unable to distinguish between
relapse and normal age changes. We can either
accept these long-term changes as part of the
normal ageing process or resist them with
long-term retention.8
Rationale behind the use of xed
Many studies have shown that long-term
stability is problematic when retention is
discontinued, with some degree of relapse
inevitable.1,2,9 Previous researchers have tried
to define acceptable levels of relapse after
retention has been stopped. Little etal.10
and Alexander etal.11 have suggested that
irregularity of <3.5mm in the labial segment
may be considered an acceptable level of
relapse; however, some patients would not
tolerate this amount of irregularity. As a
result, the use of long-term retention has been
recommended.12,13 Fixed retainers can be used
for long-term retention with minimal patient
Surveys on contemp orar y retention
protocols show an increase in the use of xed
retainers, with clinicians either preferring
lifelong retention or not dening a precise
time to remove them.12,15,16,17,18 However,
long-term retention has implications for the
maintenance of xed retainers and there are
questions about who is responsible for the care
of these retainers.19 Is the clinician who placed
the retainer responsible for monitoring and
maintaining it? Studies have shown that within
a couple of years in retention, the majority of
the patients stop attending for regular check-
ups for various reasons or seek treatment only
when the problem is apparent.20 This may
lead to problems only being noticed when it
is too late – when relapse has occurred and
re-treatment is required. It has been suggested
that, provided appropriate training and
remuneration is in place, the retainers can be
monitored as part of a patients normal regular
dental check-up and specialist advice sought if
problems are noticed.19
According to some studies, xed retainers have
been found to be safe and predictable,21 and
compatible with periodontal health.9 However,
they undoubtedly do have some disadvantages
Encourag es+balanced+discus sion+amon g+the+
with+bon ded+retainers,+focusing+o n+the+possible+
Discusses the factors inuencin g occurrence of
complications and the potential negative eec ts on
Stresses+the+importance+of+monitor ing+bonded+
order+to+prevent+development+of+s evere+clinical+
retainers is being increasingly used among clinicians. Bonded retainers can provide an ecient and attrac tive method
1Depar tment of Ortho dontics, Clinic o f Dental Medicine,
First M edical Faculty, Char les Universit y, Katerinska
32, Prague 2, 1280 0, Czech Republic ; 2Orthodont ic
Depar tment, St Luke’s Hospi tal, Little Ho rton Lane,
Bradfo rd, BD5 0NA, UK; 3D epartment of O rthodontic s,
Clinic of De ntal Medicine, Palac ky Universit y, Palackeho
700/12, Olomouc , 77900, Czech Rep ublic."
*Corresp ondence to: Josef Ku čera"
Email addr ess:
Accepted&8&S eptember&2020
and complications associated with their use,
which include:
Failure of bonded retainer. is may occur
due to debonding of the composite adhesive
from the tooth, failure of the bond between
the wire and the composite, or fracture of
the retainer. Failure rates may be aected
by clinical technique, the choice of retainer
design and material, adhesive used and the
location of the retainer14,22,23,24,25
Adverse eect on periodontal health26,27,28
Unwanted to oth movement with the
retainer insitu14,20,29,30
Adverse eect on general health.31,32
When long-term or lifelong retention is
indicated, an appreciation of these pitfalls and
complications becomes crucial.
Failure of a bonded retainer is a relatively
common complication (Fig. 1) and may be
due to detachments of the wire on single to
multiple teeth either at the enamel-composite
interface (type1), wire-composite interface
(type2) or retainer fracture (type 3).24,33 e
prevalence of common complications reported
in the literature varies significantly, from
1%34 up to 53%.35 e wide range in reported
prevalence of failure is due to influence
from a number of factors, including: how
the complications or failures are recorded,
categorised and calculated;24,25 sele ction
bias;25 experience of the clinician bonding
the retainer;25,33,36 dierence in wire type and
dimension,21,22,24,35 and adhesive material
used;23,37,38 type of retainer;14,25,28,34 and, possibly
most importantly, the length of observational
period.24,25,39 If bo nded reta iner s are l e in pl ace
for the long term, it is almost inevitable that
one of the common complications will occur
at some stage. It is, however, very important
to note that these complications, even when
reported as a failure, do not always negatively
aect or signicantly reduce the eectiveness
of the retainer, provided that the problems are
recognised soon and the retainer is restored to
its full function (Fig. 2).25
Fac tors that affect failure rates are
e most common complication is detachment
at the enamel-composite interface and this may
be attributed to technical problems during
the bonding procedure, such as moisture
contamination, insucient cleaning of the
enamel surface before bonding or movement
of the wire during the bonding procedure.22,40
Most of the enamel-composite failures will
therefore appear within the rst six months
aer bonding of the xed retainer.22,35,36,41 It has
been shown that failure rates are lower among
more experienced operators who have placed
more bonded retainers.25,33,36,42
There is a lack of consensus among
orthodontists regarding the optimal type of
retainer wire.12,15,16 e most commonly used
materials for xed retainers are either exible
multi-strand stainless steel wires bonded to
all the anterior teeth, or thick monolament
stainless steel, cobalt-chromium or titanium-
moly bdenum wires bonded only on the
canines (Fig. 3).
Fractures of retainer wires are less frequent
than debonds but are more likely to occur
in places where occlusal contact with the
retainer is present, typically between upper
lateral incisors and canines or lower canines
and first premolars.21,24 The probability of
fracture may increase with time due to wire
fatigue or damage by food particles or forces
of mastication.24
e thin, exible multi-strand retainers are
available in dierent diameters, cross-sections
Fig. 1 Dierent types of failures of bonded retainers. a) Type1 – detachment on the enamel-composite interface. b) Type2 – gradual wear and
fractures of the adhesive on the wire-composite interface. c) Type 3 – wire fracture
Fig. 2 a, b, c, d) Repair of retainer failure is simple when identied in a timely manner and does
not necessarily reduce the eectiveness of the retainer
and inner organisation of the filaments.
Diameters of the thin flexible wires range
between 0.0155” to 0.0215” with round cross-
section or0.016x0.022” with rectangular
cross-section. e number of laments range
from 3 to 8and these can be organised and
manufactured in dif ferent patterns; for
example, twisted, braided or coaxial. The
mechanical properties of the wire allow
physiological movement of included teeth
while suciently splinting the teeth at the
same time.43 All multi-strand wires seem to
full this criteria; however, small diameter
wires with fewer laments are more susceptible
to damage and have been reported to have
increased failure rate due to lower bond
strength and mechanical instability.12,21,24,29,37
Multi-strand wires also exhibit better retention
of the wire to the composite when compared
to monolament wires.37
e diameter of the thick wires is typically
between 0.025” to 0.036” and these are usually
round in cross-section. These retainers
have lower failure rates when compared
to thin multi-strand wires bonded to all
incisors.14,22,25 ey are sometimes referred
to as ‘fail-safe bonded retainers’ because,
if they become detached from one tooth,
patients will be aware of this and can contact
their orthodontist. Retainers bonded only
to canines are also easier to keep clean.9,21,38
Lower frequencies of failure and thus higher
survival rates have been reported with thick
retainers bonded only to canines. However,
because they are not attached to the incisors,
these teeth are more prone to movement.14,22,44
Dead-so stainless steel wires are also used
due to the ease of use related to the enhanced
degree of formability, but they can be deformed
by the forces of mastication and food particles,
and they do not maintain the intercanine width
as well.21,45
Fibre-reinforced composite, bre-reinforced
plastic or even ceramic materials can be
used.28 However, fibre-reinforced retainers
are prone to greater failure rates due to a lack
of exibility.46 More recently, monolament
nickel-titanium wires constructed by CAD/
CAM procedures have been described and are
currently being investigated.47
Retainer wires are attached to teeth by a layer
of adhesive material. Chemically- or light-
cured composite resin materials can be used
and show similar failure rates.23,37 Flowable
light-curing hybrid composite resin materials
with decreased amount of filler particles
are usually preferred among clinicians for
the ease of application, setting ‘on demand’
and polishability.48 Harder and more wear-
resistant posterior composite materials have
also been suggested as adhesive materials for
xed retainers to resist long-term abrasive
wear from tooth brushing and diet. However,
these rigid materials may be more fragile and
therefore also more prone to failure at the wire-
composite interface, and may complicate wire
Failure between the wire and the composite
is less common but may occur as a result of
gradual wear of the composite layer during
mastication, toothbrush abrasion or occlusal
contacts. e prevalence of this wear increases
with time.22,24 e recommended thickness of
the composite layer has been reported to be
between 0.25mm to 1mm.34 icker layers
exceeding 1mm are not believed to provide
additional advantage.37 If long-term retention
is planned, the composite layer needs to be
checked regularly and will occasionally require
repair to restore function and stability.
Failures of xed retainers are more likely
to occur in the upper arch.24,28,41 is may
be due to occlusal factors. Even when the
wire is placed out of occlusion, occlusal
contacts due to functional movements of the
mandible cannot be excluded and these may
lead to gradual wear of the adhesive layer or
Fig. 3 Dierent thin multi-stranded or thick monolamental stainless steel archwires are used
for construction of bonded retainers. a) 0.0175” three-strand twisted wire. b) 0.0215” six-
stranded coaxial wire. c) 0.016x0.022” eight-stranded braided wire. d) 0.036” monolamental
stainless steel wire bonded only to canines. Panel d is courtesy of Dr Gudrun Edman Tynelius
Fig. 4 Adverse eects on gingival health relate to bonding procedures and on the level of oral
hygiene. a) Bonding of the retainer too close to the gingiva will result in plaque accumulation
and gingival hyperplasia. b) Staining and calculus may form around the retainer; regular oral
hygiene recalls are therefore necessary
wire-fatigue fractures.49 Retainers bonded
to incisors are more prone to failure when
compared to canines in the mandibular arch,
while little difference was found between
central and lateral incisors in the maxillary
arch.25 However, the incidence of failures
increases when upper retainers are extended
to the maxillary canines21 and the first
premolars are included in the lowerjaw.50
Negative eect on periodontal health
Because of the increasing acceptance of
long-term or even lifelong retention with
bonded retainers, t he potential negative
eects on periodontal health are worthy of
consideration. Whi le some authors have
reported no negative effect on adjacent
hard and so tissues in the long term,9,21
increased plaque and calculus accumulation
in the vicinity of bonded retainers with no
detrimental eect on the adjacent tissues is
commonly suggested (Fig. 4),26 and worsening
of periodontal health due to higher plaque
and calculus accumulation in association
with the long-term use of bonded retainers
has also been demonstrated.27 e presence
of calculus in gingival regions adjacent to
bonded retainers may also predispose the
patient to an increased incidence of gingival
recessions.51 It is therefore important to place
the retainer at a sufficient distance from
gingiva, to avoid touching the papillae (in
the incisal third of teeth), ensuring that the
adhesive layer is smooth with no undercuts
predispo sin g to pl aque and calc ulu s
retention.21,22,26,27 is might be challenging
in the upper incisor region, where occlusal
contacts with the edges of the mandibular
incisors may force the clinician to position
the retainer closer to the gingiva. Regular
check-ups and hygiene recalls are needed
to monitor the periodontal health of every
patient, particularly in cases of long-term or
lifelong retention.
Unwanted tooth movement within the retainer
segment can occur even with the retainer
insitu with no previous or apparent failure of
the retainer. Two distinct forms (Fig. 5) can
be identied:
Change in torque between two adjacent
teeth (X eect)
Opposite tipping of contralateral canines
with torquing of the whole anterior segment
(twist eect).
The tooth movement in these cases does
not occur in the direction of original tooth
position and thus cannot be classif ie d
as relapse.14,20,29 The prevalenc e of these
unexpected complications has been reported
to be quite low, between 1.1%20 and 5%.29
However, around 50% of patients presenting
with these complic at ions may requ ire
orthodontic re-treatment (Fig. 6).29 The type
of treatment required varies depending on
the extent of the tooth movement, ranging
from a simple clear plastic appliance based
on a set-up model and short-term fixed
appliance-based treatment when single teeth
are involved, to more comprehensive full
fixed appliance re-treatment and periodontal
surgery when larger changes occur.30
The aetiology of these changes remains
unclear; however, the presence of a tooth-
moving force is a prerequis ite. Sp ec if ic
aetiological factors may be related to:52
The most frequently dis cussed factors
include instability of the thin multi-strand
spiral wires (unwinding or untwisting of
the wire),20,24,29,53 insufficient passivity of
the bonded wire or activation during the
bonding procedure,29 type or position of
the retainer wire,52 or activation of the wire
during the retention period due to occlusal
contact, habits or damage by hard food
particles, which may undoubtedly generate
forces capable of tooth movement.22,29,54 With
increasing time, progressive wear of the
adhesive layer occurs;24 consequently, larger
portions of wire are exposed and this increases
the risk of activation by occlusal forces and
forces of mastication.52 e possible role of
unrecognised failure on the wire-composite
interface due to microleakage55 creating a
‘tunnelling eect’ has also been suggested,
allowing torquing to occur around the wire
as a centre of rotation.52
It has also been hypothesise d that patient-
related factors including bad habits and
par afunction, such as chewing on pens,
sagittal and ver tical relapse, relaps e in
intercanine wi dth or anterior vec tor of
occlusal force, may be influential.52 Other
contributing anatomica l factors that may
influence the severity and speed of the
unexpecte d tooth movement may also
be the individual quality and quantity of
adjacent bone and soft tissues. It has been
well documented in the literature that the
cortical plate surrounding the lower incisors
is often very thin or may show frequent
dehi scenc es an d fenestrations even in
untreated subjects,56,57 especially in those
Fig. 5 Two distinct types of unexpected complication associated with bonded retainers
can arise. a, b) X eect presents with change in torque on two adjacent incisors. c, d) Twist
eect presents with opposite tip on contralateral canines and change in torque in the incisor
region. In severe cases, gingival recession may be present and adjunctive periodontal surgical
treatment may be required
with increased vertical dimension,58 and
orthodontic treatment can in some cases
further accentuate the reduction of already
deficient buccal cortical plate.59 The timing
of onset of these complications var ies,
ranging f rom months to over ten years,
and most likely depends on the aetiological
factor.20,29,53 Un doubt edl y, mis takes in
fabrication and insufficient passivity while
bonding the retainer are likely to occur
rapidly in the first months after bonding
if not counteracted by another retention
device, while other aetiological factors may
act slowly and become apparent after several
years of retention. It is difficult to establish
the tim ing of the onse t of unexp ected
complications, particularly as attendance
of patie nt s du rin g rete ntion pha se i s
intermittent and the unwanted movement
may go unnoticed until it reaches a level
that is apparent to the patient, dentist or
Adverse eect on general health
It has been suggested that prolonged retention
with bonded retainers may have an eect on
general health as a result of problems with the
biocompatibility of the wires and adhesives.31
is is controversial and there is little clear
evidence to suggest bonded retainers can aect
general health. Composite resins have been
reported to have potentially negative eects
on general health as they contain bisphenol A
(BPA), possibly resulting in decreased sperm
count and fertility, increased risks of breast and
prostate cancers, diabetes, negative behavioural
effects or altered immune functions.60 The
amounts of BPA leaching from bonded
retainers invivo is negligible, but care must be
taken to reduce the immediate leach of BPA
out of the uncured layer of adhesive by proper
light curing and polishing.32 Most bonded
retainers are made of stainless steel, which
contains 8% nickel. Nickel hypersensitivity is
common in the population, with an increase
in prevalence in recent decades.61 Fortunately,
the frequency and magnitude of allergic
responses to nickel intraorally is signicantly
lower compared to skin.62 Severe nickel allergy
reactions to xed orthodontic appliances are
rare and present extraorally with swelling of
the lips and eczema lesions, and intraorally
with symptoms of burning sensation, loss of
taste and gingival hyperplasia.63 One case of
facial eczema attributed to the use of a xed
retainer has been reported.64
Bonded retainers are generally well tolerated
because they are invisible, xed in place and
appear to be safe in the long term for the vast
majority of patients. However, they can be
associated with failure, such as detachment or
fracture, and rare but potentially signicant
unwanted tooth movement with the retainer
still insitu. Patients with bonded retainers
therefore require regular review. Patients
and orthodontists, but also treating dentists
and hygienists, should be aware of these
complications so that any problems can be
identied and intercepted as soon as possible,
in order to mitigate the development of
potential adverse eects.
Conict of interest
e authors declare no conict of interest.
1."Sadow sky C, Schneide r BJ, BeGole EA, Tahir E.
Long-t erm stabilit y after ortho dontic treatme nt:
nonex traction wit h prolonged rete ntion. Am JOrth od
Dentofa cial Orthop 199 4; 106: 243–249.
2."Litt le RM, Riedel R, År tun J. An evaluati on of changes in
mandibula r anterior alignme nt from 10–20years p ost-
retenti on. Am JOrthod 198 8; 93: 423– 428.
3."Blake M, Bibby K . Retention and s tability: A rev iew of
the liter ature. Am JOrtho d Dentofacial O rthop 1998;
114: 299– 306.
4. Sinclair PM, L ittle RM. Dento facial maturatio n of
untreat ed normals. Am JOr thod 1985; 88: 146–156.
5. Bishara S, Tre der JE, Damon P, Olsen M. Changes i n the
dental ar ches and dentitio n between 25and 45yea rs of
age. Angl e Orthod 1996; 66 : 417–422.
6. Behrent s RG. Growth in th e aging craniof acial skeleton .
Monogra ph 17, C raniofacial G rowth serie s. Ann Harbou r:
Centre fo r Human Growth an d Development; Un iversity
of Michigan , 1985.
7."Ab dulraheem S, Schü tz-Fransson U, B jerklin K. Teeth
movemen t 12years af ter orthodon tic treatment wi th
and with out retainer: re lapse or usual change s? Eur
JOrthod 2020; 42: 52–59.
8. Nanda RS, Nanda SK. Consideration of dentofacial growth
in long-term retention and stability: Is active retention
needed? Am JOrthod Dentofacial Orthop 1992; 4: 297–302.
9. Boot h FA, Edelman JM, Pro t WR. Twenty-year
follow- up of patients w ith permanentl y bonded
mandibula r canine-to- canine retainer s. Am JOrthod
Dentofa cial Orthop 2 008; 133: 70 –76.
10. Lit tle RM. The irregu larity index: a q uantitative s core
of mandibu lar anterior alignm ent. Am JOrtho d 1975;
68: 554–563.
Fig. 6 Re-treatment of X eect and twist eect may require a, b, c) partial xed appliance-
based treatment or d, e, f) full-arch xed appliance treatment combined with gingival surgery,
depending on the severity. Images reproduced with kind permission from J. Kučera etal.,
‘Interdisciplinary orthodontic and periodontal treatment of a severe unexpected complication
associated with a lower xed retainer: a case report’, Journal of Clinical Ort hodontics, 201665
11."A lexander RG. The Al exander Disc ipline – Volume 2:
Long-t erm stabili ty. 1st ed. Hanover Par k: Quintessenc e
Publishin g, 2011.
12."Pad mos JAD, Fudalej PS, Renkema AM . Epidemiologic
study o f orthodonti c retention proce dures. Am JOrth od
Dentofa cial Orthop 2 018; 153: 496 –504.
13."Ren kema AM, Fudalej PS. Fixe d-retainers: l ong-term
eec tiveness. In Kats aros C, Eliades T (eds) Stab ility,
Retenti on, and Relapse in O rthodont ics."1st"ed."pp"
203–208 . Surrey: Quinte ssence Publishing, 2 017.
14. Renkem a AM, Renkema A, Bronk horst E, Kats aros C.
Long-t erm eective ness of canine-t o-canine bon ded
exible s piral wire lingual re tainers. Am JOr thod
Dentofa cial Orthop 2 011; 139 : 614–621.
15. L ai CS, Grossen JM, Renke ma AM, Fudalej PS,
Katsar os C. Orthodo ntic retention pr ocedures in
Switze rland. Swiss Dent J 2014; 124: 655 –661.
16. Prat t MC, Kluemper GT, Har tseld JK, Fardo D, Na sh
DA. Eval uation of retentio n protocols among me mbers
of the Ame rican Associa tion of Orthod ontists in the
United St ates. Am JOrtho d Dentofacial O rthop 2011;
140: 520–526 .
17."Renkema AM, S ips ETH, Bronkhors t E, Kupers-
Jagtman AM . A survey on ort hodontic reten tion
precedu res in the Netherl ands. Eur JOrtho d 2009; 31:"
18. Valiath an M, Hughes E. Resul ts of a survey- based study
to identi fy common reten tion practices in t he United
States. A m JOrthod De ntofacial Or thop 2010; 137:"
19. Li ttlewood SJ. Res ponsibilities an d retention. APOS
Trends Ort hod 2017; 7: 211–214.
20. Kucera J, Marek I. U nexpected com plications asso ciated
with man dibular xed retai ners: a retrospe ctive study.
Am JOrt hod Dentofaci al Orthop 2016; 149: 202–211.
21."Zachris son BU. Long-term e xperience with d irect
bonded r etainers: Updat e and clinical advice. JC lin
Orthod 2007; 41: 728–737.
22."Årtun J , Spadafora AT, Shapiro PA . A 3-year follow- up
study o f various type s of orthodont ic canine-to- canine
retaine rs. Eur JOrthod 1997; 5: 501 –509.
23."Pandis N, Flem ing PS, Kloukos D, Polyc hronopoulou
A, Kat saros C, Eliades T. Sur vival of bonded li ngual
retaine rs with chemical o r photo polymer ization over a
2-year per iod: a single-cen tre, randomized con trolled
clinical t rial. Am JOrtho d Dentofacial O rthop 2013; 144:"
24. Dahl EH, Za chrisson BU. Long -term experien ce with
direct- bonded lingual r etainers. JClin O rthod 1991; 25:"
619– 630.
25. Kocher KE, Ge bistorf MC, Pand is N, Fudalej PS,
Katsar os C. Survival o f maxillary and ma ndibular
bonded r etainers 10to 15years af ter orthodon tic
treatm ent: a retrospec tive observ ational study. Pro g
Orthod 2019; 20: 28.
26. Årtun J. C aries and period ontal reactio ns associated
with lon g-term use of di erent types of b onded lingual
retaine rs. Am JOrtho d 1984; 86: 112–118.
27."Pandis N, Vlaho poulos K, Madiano s P, Elia des T. Long-
term per iodontal stat us of patients wi th mandibular
lingual xe d retention. Eur JOr thod 2007; 29: 471–476.
28. Tacken MP, Cosyn J, D e Wilde P, Aert s J, Govaerts E,
Vannet BV. Glass b re reinforced vers us multistrand ed
bonded o rthodontic r etainers: a 2year pr ospective
multi- centre study. Eur JO rthod 2010; 32: 117–123.
29. Ka tsaro s C, Li vas C, R enkema AM. Une xpect ed
comp licati ons of b onded mandib ular lin gual
retainers. Am JOrthod Dentofacial Orthop 2007; 132:"
30. Shaugnessy TG , Prot WR, Samara SA . Inadverten t
tooth mo vement with xed lin gual retainers . Am%
JOrth od Dentofacial O rthop 2016; 149: 277–286.
31."Eliades T, Vout sa D, Sifakakis I, Makou M , Katsaros C.
Release of b isphenol-A fr om a light-cured ad hesive
bonded t o lingual xed retai ners. Am JOrth od
Dentofa cial Orthop 2 011; 139 : 192–195.
32."Kang YG, K im J-Y, Kim J, Won P-J, Nam J -H. Release
of bisphen ol A from resin compos ite used to bond
orth odontic lingual re tainers. Am JOr thod Dentofa cial
Orth op 2011; 14 0: 77 9–789.
33."Forde K , Storey M, Littl ewood SJ, Scott P, Luther F,
Kang J. Bon ded versus vacuum -formed ret ainers: a
randomiz ed controlled tr ial. Part 1: stabilit y, retainer
survi val, and patient sa tisfaction o utcomes after 12
months . Eur JOrthod 2018; 40: 387–398.
34. Ro gers MB, Andrews LJ . Dependable tech nique for
bonding a 3x 3 r etainer. Am JOrth od Dentofacia l Orthop"
2004; 126: 231–233.
35. Störman n I, Ehmer U. A prospec tive randomized s tudy
of diere nt retainer ty pes. JOrofac Or thop 2002; 63:"
36. Lie Sam Foek DJ, Ozc an M, Verkerke GJ, Sandha m
A, Dk stra PU. Surviv al of exible, braid ed, bonded
stainl ess steel lingual re tainers: a histo ric cohort stu dy.
Eur JOrt hod 2008; 30: 199–20 4.
37."Bearn DR, McC abe JF, Gordon PH , Aird JC. Bonded
orth odontic retaine rs: the wire compos ite interface. Am%
JOrth od Dentofacial O rthop 1997; 111: 67–74.
38. Zachrisson BU. T hird generation ma ndibular bonded
lingual 3 –3 retainer. JClin Or thod 1995; 29: 39– 48.
39. Sfondrini MF, Fraticel li D, Castellazzi L, S cribante
A, Gandi ni P. Cli nical evaluation of b ond failures
and sur vival betwee n mandibular canine -to-canine
retaine rs made of exible s piral wire and bre -
reinforce d composite. JClin E xp Dent 2014; DOI:
40. Flemi ng PS, Johal A, Pandis N . Self-etch pr imers and
conventi onal acid-etch t echnique for ort hodontic
bonding: a s ystematic rev iew and meta-ana lysis. Am%
JOrth od Dentofacial O rthop 2012; 142: 8 3–94.
41. Seg ner D, Heinrici B. Bonde d retainers – clin ical
reliabili ty. JOrofac Ort hop 2000; 61: 352–358.
42. Scheibe S, R uf S. Lower bonde d retainers: sur vival
and failur e rates particu larly considerin g operator
experi ence. JOrofac Ort hop 2010; 71: 300–307.
43. Watted N, Wi eber M, Teuscher T, Schmit z N.
Comparis on of incisor mobili ty after inser tion of
canine -to-canine lin gual retainers b onded to two or
to six teet h. A clinical stud y. JOrofac Or thop 2001; 62:"
44. Al-N imri K, Al Habashn eh R, Obeidat M. Ging ival health
and relaps e tendency: a pro spective stu dy of two
type s of lower xed retai ners. Aust Or thod J 2009; 25:"
45. Gunay F, Oz AA. Clin ical eective ness of 2 ortho dontic
retaine r wires on mandibular a rch retention. Am%
JOrth od Dentofacial O rthop 2018; 153: 232–238.
46. Torkan S, O shagh M, Khojast epour L, Shahidi S, He idari
S. Clinica l and radiographi c comparison of the e ects
of two t ypes of xed ret ainers on periodo ntium – a
randomiz ed clinical trial. Pr og Orthod 2014; 15: 47.
47. Kravi tz ND, Grauer D, Schumach er P, Jo Y- M. Memotain:
A CAD/CA M nickel-titan ium lingual retaine r. Am%
JOrth od Dentofacial O rthop 2017; 151: 812–815.
48. Sifak akis I, Katsaro s C, Zinelis S, Eliades T. Biom aterials
used for  xed retainers in or thodontic s. In Katsaros
C, Eliades T (e ds) Stability, Rete ntion, and Rela pse in
Orthodontics. 1st ed. pp 189 –202. Surrey: Quinte ssence
Publishin g, 2017.
49. Zachrisso n BU, Büyükyilmaz T. Bo nding in orthod ontics.
In Graber LW, Vanars dall RL, Vig KWL (eds)
Orth odontics – Curr ent principle s and technique s. 5th ed.
pp 727–784. Phil adelphia: Elsevier M osby, 2012.
50. B earn DR. Bonded or thodontic re tainers: a revie w. Am%
JOrth od Dentofacial O rthop 1995; 108: 207–213.
51. A lbandar JM, Kingman A . Gingival reces sion, gingival
bleedin g, and dental calcu lus in adults 30year s of age
and older i n the United States , 1988–1994 .JPeriodontol"
1999; 70: 30 –43.
52. Kucera J, Mare k I, Hanzelka T, Kaminek M. Une xpected
complica tions of xed retai ners. Ortodoncie 2015; 24:"
53. Brenchley ML . A cautionary t ale of simplied re tention.
Br JOrt hod 1997; 24: 113–115.
54. Sif akakis I, Pandis N, Elia des T, Makou M, Katsaros C ,
Bouraue l C. In-vitro as sessment of the for ces generated
by lingual  xed retainers. A m JOrthod De ntofacial
Orth op 2011; 13 9: 4 4–48.
55. Uysal T, Bay sal A, Usumez S, Ulker M . Microleakage
betw een composite-w ire and composite -enamel
interf aces of exible spir al wire retainer s. Part 1:
comparis on of three composi tes. Eur JOrthod 2 009; 31:"
56. R ichman C. Is gingival r ecession a consequ ence
of an ort hodontic tooth s ize and/or tooth positi on
discrepa ncy? “A paradigm s hift”. Compend Cont in Educ
Dent 2011; 32: 62–69.
57. Nahm K-Y, Kang J-H, Moo n S-C etal. Alve olar bone loss
around in cisors in Class I bide ntoalveolar pro trusion
patient s: a retrospec tive three- dimensional cone bea m
CT stu dy. Dentomaxill ofac Radiol 2012; 41: 481– 488.
58. Yagc i A, Veli I, Uysal T, Ucar FI, Oze r T, Enhos S.
Dehiscen ce and fenestrat ion in skeletal Class I , II, and
III malocc lusions assesse d with cone-bea m computed
tomogra phy. Angle Ortho d 2012; 82: 67–74.
59. Kim Y, Park JU, Kook Y. Alveolar bone loss around incisors
in surgical skeletal class III patients. A retrospec tive 3-D
CBCT study. Angle Orthod 2009; 79: 676– 682.
60. Pel ch K, Wignal JA, Go ldstone AE etal. A scop ing
review of t he health and toxic ological acti vity of
bispheno l A (BPA) structur al analogues and fu nctional
alterna tives. Toxicology 2019; 424: 152235.
61. Rie tschel RL, Fow ler JF, Warshaw EM etal. Detec tion
of nickel sen sitivity has in creased in Nort h American
patch- test patients . Dermatitis 2008; 19: 16–19.
62. Neville BW, Damm DD, All en CM, Chi AC. Chapter
9: Allerg ies and immunologi c diseases. In Neville
BW, Damm DD, Allen CM, C hi AC (eds) Oral and
Maxill ofacial Pathol ogy. 4th ed. pp 321.St Louis: El sevier,
63. N oble J, Ahing SI, Kar aiskos NE, Wiltshir e WA. Nickel
allergy a nd orthodont ics: a review and re port of two
cases. B r Dent J 2008; 204: 297–30 0.
64. Feilze r AJ, Laeendecker R , Kleverlaan CJ, van S chendel
P, Muris J. Facial eczem a because of ort hodontic xed
retaine r wires. Contac t Dermatitis 20 08; 59: 118–120.
65. Kučera J, Stre blov J, Marek I, Hanzelk a T.
Interdis ciplinary or thodontic and pe riodontal trea tment
of a severe u nexpected com plication assoc iated with a
lower xe d retainer: A case r eport. JClin Or thod 2016;
50: 34–39.
... These devices have been reported to be reliable and safe; nevertheless, they can have disadvantages and can lead to complications. For example, they can undergo fracture or detachment on single to multiple teeth [6]. A less common, but really dangerous, problem is the unwanted tooth movement, such as crown displacement or torque movements [7]. ...
... Fixed retainers are widely used at the end of active orthodontic treatment as stability cannot be predicted at the individual level [13]. Because they are compliance-free, invisible, and appear to be safe in the long term, patients generally tolerate them well [6]. Clinicians can also choose a removable device for the retention phase because they have 3 Case Reports in Dentistry the advantage of being easier for the patient to maintain oral hygiene. ...
... Among the complications of fixed retainers, detachments, fractures, unexpected tooth movements, and difficulty in maintaining correct oral hygiene occur [6]. ...
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The use of fixed retainers at the end of an orthodontic treatment has become a standard practice. Nonetheless, orthodontic relapse can still occur, requiring retreatment in the most severe cases. This case report describes a patient with a mandibular canine to canine fixed retainer presenting uncontrolled torque on all lower anterior teeth, probably due to tongue thrust and/or activation of the wire. Multibracket orthodontic treatment was performed, and an orthodontic lingual sectional was used to control (reposition) the root movement of the lower right cuspid. This case highlights the need for clinicians and patients to be aware of the potential problems associated with bonded retainers. In addition, patients with an orthodontic fixed retainer need regular short-term observation by an orthodontist in order to detect any adverse movements and long-term control by a general dentist.
... As the long-term benefits of long-term retention have been recognised, there has been an increased use of bonded retainers. However, it is important to recognise that they do have potential complications (Kučera et al., 2021). These include: failure (Kocher et al., 2019); potential for adverse effect on periodontal health Tacken et al., 2010); unwanted tooth movement with the retainer in situ (Kučera and Marek, 2016); and adverse effects on general health (Eliades et al., 2011). ...
... Failures of bonded retainers can occur as a result of debonding of the composite from the enamel, failure between the wire and the composite or fracture of the retainer (Kučera et al., 2021). The most common failure occurs between the adhesive and the enamel (Dahl and Zachrisson, 1991;Forde et al., 2018), which may be the result of poor clinical technique (in particular, lack of moisture control during bonding). ...
... Composite does not bond chemically to wire retainers, so this bond relies on mechanical retention between the composite and the surface of the wire. The likelihood of wire fracture depends on the type and diameter of wire used, and whether there is repeated stress on the wire, as a result of direct occlusal trauma from the opposing arch or repeated flexing of the wire (Kučera et al., 2021). ...
Background Bonded retainers are widely used to maintain the positions of anterior teeth after orthodontic treatment. Various types of bonded retainer exist however, there is a lack of evidence to indicate which type is superior. Aim To compare upper and lower CAD/CAM nitinol bonded retainers (Memotain ® ) with upper and lower chairside rectangular-chain bonded retainers (Ortho-FlexTech™), in terms of stability, retainer failures and patient satisfaction. Trial design Multi-centre, two-arm, parallel-group, randomised controlled clinical trial with 1:1 allocation. Setting Three trial centres: University Teaching Hospital; District General Hospital; and Specialist Orthodontic Practice. All treatment was provided free as part of a state-funded healthcare system. Materials and methods A total of 68 patients were randomly allocated to receive either upper and lower Memotain ® bonded retainers or upper and lower Ortho-FlexTech™ bonded retainers. Ten trained operators placed and reviewed the bonded retainers. Measurements were carried out on study models taken at debond and after six months. Patient satisfaction questionnaires were completed at six months following debond. Results The trial was terminated due to the high number of failures (50%) of the upper Memotain® retainers within six months. Memotain ® retainers were three times more likely to fail (unadjusted hazard ratio = 2.82, 95% confidence interval = 1.00-7.99) than Ortho-FlexTech™ retainers at six months in the upper arch. Patients were satisfied with both types of retainer. Limitations Early termination of the trial means that the a priori sample size was not reached, so outcomes should be interpreted with caution. Conclusion The trial was terminated early due to the high failure rate of upper Memotain ® bonded retainers. They had a higher risk of failure in the maxillary arch when compared to upper Ortho-FlexTech™ bonded retainers after six months.
... Indeed, WS seems to be due to a combination of different and multifactorial etiologies. In addition, it appears that the delay in apparition varies with etiology [29]. Early WS could probably be explained by an error in wire adaptation (lack of passivity) or bonding [29]. ...
... In addition, it appears that the delay in apparition varies with etiology [29]. Early WS could probably be explained by an error in wire adaptation (lack of passivity) or bonding [29]. When WS appears several years after orthodontic placement, wire-related etiologies are preferred. ...
... When WS appears several years after orthodontic placement, wire-related etiologies are preferred. Regarding dysfunction, some authors hypothesized that oro-vestibular forces exerted by the tongue could cause undesirable movement [2,22,29], although Shaugnessy et al. excluded the role of the tongue because its pressure would be less than that required to deform the wire [4]. In addition, the risk of wire deformation also increases with time due to the progressive wear of the composite, which results in a larger section of the wire being exposed to deformation [29]. ...
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(1) Background and objective: Tooth movements described as unexplained, aberrant, unexpected, unwanted, or undesirable can occur in the presence of an intact orthodontic retention wire, without detachment or fracture. This iatrogenic phenomenon, known little or not by many practitioners, responsible for significant dental and periodontal complications, both functional and aesthetic, is called “Wire Syndrome” (WS). It is therefore considered an undesirable event of bonded orthodontic retainers, which must be differentiated from an orthodontic relapse. The objective was to perform, for the first time, a systematic review of the literature in order to define the prevalence of WS and to study its associated clinical characteristics. (2) Methods: A systematic review of the literature was performed following the guidelines of Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) and recommendations using an electronic search strategy on four databases complemented by a manual search. All the prospective and retrospective clinical studies, including case reports and series, written in English or French, clearly mentioning the description, detection, or management of WS were included. Three independent blinding review authors were involved in study selection, data extraction, and bias assessment using the Mixed Methods Appraisal Tool (MMAT). (3) Results: Of 1891 results, 20 articles published between 2007 and 2021 fulfilled the inclusion criteria, with a globally high risk of bias since 16 articles were case report/series. The analysis of each article allowed the highlighting of WS through 13 categories, as follows: prevalence, apparition delay, patient characteristics, arch and tooth involved, families of movements, dental and periodontal consequences, type of wire, risk factors, etiologies, treatment, and preventive approach. (4) Conclusion: This systematic review of the literature elaborated a synthesis on WS, allowing general practitioners, periodontists, and orthodontists to understand this adverse event, to facilitate the diagnostic approach, and to underline preventive measures against WS. This review was registered in the International Prospective Register of Systematic Reviews (PROSPERO; number CRD42021269297).
... The main factors to consider for a longterm s uccessful lingual retainer are the material used in its fabrication (stainless steel, FRC, etc.), the adhesive material used for retainer bonding, the number of teeth bonded, and the location on t he lingual site of the teeth where the retainer is bonded (Kučera et al., 2021). ...
Background and Objectives: This in vitro study was performed to assess the shear bond strength (SBS) of three different fixed lingual retainers using two types of different adhesive systems and fracture modes (Adhesive Remnant Index -ARI) of different retainer’s wire-adhesive combination. Materials and methods: one hundred eighty (180) extracted sound human upper premolar teeth were divided into two groups (90 for each group). Then each group subdivided to three subgroups (30 for each subgroup) bonded with three different fixed lingual retainers (Straight-8 strand braided flat soft wire 0.028 x 0.008 inches db UK, 3M Unitek coaxial multi strand 0.0195-inch wire USA and Ultra-Flex Lingual Retainer 0.9 mm x 0.4 mm IOS USA), which were bonded to the lingual surface of the teeth using two types of different adhesive systems (3M™ Transbond™ LR Adhesive USA and HeyTec Flow SE Composite, Heydent Germany). To assess the shear bond strength, the samples were debonded using a Universal testing machine (Instron). For each specimen, the site of failure was examined using a Stereomicroscope. One-way analysis of variance was used for the statistical analysis. Results: There was a high statistically significant difference between the two study groups (p < 0.001). Straight-8 strand braided flat soft wire combined with 3M Transbond LR Adhesive had the strongest shear bond strength (14.0 ± 4.0 MPa) whereas the minimal SBS was noted in Ultra-Flex Lingual Retainer 0.9 mm x 0.4 mm bonded with HeyTec Flow SE Composite (4.5 ± 2.7 MPa). The site of failure in group one was predominantly at the wire composite interface (cohesive failure), while in group two was in enamel/composite interface (adhesive failure). Conclusion: The simplified bonding procedures (self-etching composite) resulted in unfavorable reduction in shear bond strength. There is still support for the traditional multi-step adhesive technique
... More information about safety issues is provided in other papers in this issue. 66,67 Are fixed retainers more likely to be associated with periodontal breakdown? ...
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In view of the diversity of orthodontic presentations, a single optimal retention protocol does not exist, with approaches tailored based on pre-treatment characteristics, treatment-induced changes and general patient characteristics. However, orthodontic practitioners should be responsive to the best available evidence to formulate optimal retention protocols in terms of appliance type, design and regimen, in particular. Based on a comprehensive search strategy, we discuss fundamental aspects concerning orthodontic retention of particular interest both to orthodontists and general dentists. These include stability and periodontal outcomes, cost-effectiveness, patient experiences, survival and failure rates of retainers, and the duration of retention.
Los ortodoncistas deben informar completamente a los pacientes sobre las implicaciones del tratamiento de ortodoncia y la subsiguiente necesidad de retención. Esta revisión brinda una actualización sobre las recidivas, los movimientos no deseados y los diferentes factores que pueden causar la pérdida de estabilidad después del tratamiento de ortodoncia. Dado que es difícil predecir qué pacientes presentarán algún grado de pérdida de estabilidad después del tratamiento, es importante que sean tratados como si tuvieran un alto potencial de recaída. La presente revisión incluyó una búsqueda bibliográfica en las principales fuentes de revisión científica, incluyendo Medline vía PubMed, Scopus y la biblioteca Cochrane. La estrategia de búsqueda se llevó a cabo hasta el 5 de mayo de 2022. Solo 34 estudios cumplieron con los criterios de selección. Nuestros resultados mostraron que mantener los dientes en la posición correcta después del tratamiento de ortodoncia es un gran desafío para los ortodoncistas. La etiología de la recaída es compleja y aún no está claramente establecida. Su origen se atribuye a factores como el tiempo de reorganización del tejido gingival y periodontal, y a los cambios producidos por el crecimiento, comprometiendo la estabilidad de los resultados alcanzados con el tratamiento de ortodoncia. La fase de retención es necesaria después del tratamiento de ortodoncia para evitar la recaída o la pérdida de los resultados de oclusión obtenidos. Sin embargo, los retenedores fijos pueden inducir un movimiento dental no deseado que puede ocurrir a pesar de que estos retenedores estén colocados e intactos. Actualmente, no hay consenso entre los ortodoncistas con respecto al tipo de alambre ideal para la contención fija. Concluimos que la recidiva postratamiento de ortodoncia es el resultado de una regresión hacia la maloclusión original. Sin embargo, también pueden ocurrir cambios en la posición de los dientes que se consideran movimientos no deseados y tienen un origen multifactorial.
Background: The aim of this trial was to assess the effect of enamel sandblasting in addition to the acid-etch technique in reducing first-time failures of fixed mandibular retainers placed over a 12-month period. Materials and methods: Ethical approval was obtained. Participants were recruited in a single private practice. The primary outcome of this study was any first-time failure of the mandibular fixed retainer assessed at three timepoints over a 12-month period. Three consecutive teeth either on the left or right side (from lower canine-lower central incisor) were randomly allocated to the intervention (sandblasting) and the control (non-sandblasted). Randomization was performed using a centralized randomization service. The patients were randomized in blocks of four and eight with allocation concealment secured by contacting the sequence generator for group assignment. Blinding of either the patient or clinicians was not possible at time of placement of the mandibular retainer. Results: One hundred and ninety-seven participants were randomized to receive enamel sandblasting (intervention) and non-sandblasting (control) in the region of the six anterior mandibular teeth in a split-mouth fashion. Participants were recruited between December 2018 to October 2020. The data for all participants were analysed resulting in 394 observations. Overall, the risk of first-time failure was 11.4%. No difference in first-time failures was observed between the intervention (sandblasting) and control (non-sandblasting) groups [hazard ratio (HR), 1.05; 95% confidence interval (CI), 0.59, 1.88, P = 0.88]. Males had a higher instant probability of first-time failures (HR, 3.18; 95% CI, 1.65-6.14; P < 0.01). Participants with a fair level of co-operation had a lower instant probability of first-time failures (HR, 0.37; 95% CI, 0.16-0.86; P = 0.02). There were no harms reported to either the participant or their dentition. Conclusions: No difference in the first-time failures of mandibular bonded retainers placed with conventional etch-bond technique with or without enamel sandblasting was observed. The overall risk of first-time failure was 11.4%. Registration: This trial was not registered prior to trial commencement.
Cerebral palsy is a common cause of chronic motor neuron impairment. A constant prevalence of 2 to 3/1000 births in industrialized countries has been described. This case report describes the treatment of a 9 year old boy presenting this form of motor neuron impairment and class II malocclusion with an overjet of 14 mm, hyperdivergent growth pattern and various habits. Orthodontic treatment consisted mainly of a two-phase treatment. The first phase was treated with removable appliances and followed by a phase with fixed appliances. Treatment duration with removable appliances was 4 years and 5 months and for the fixed appliance phase, 1 year and 7 months. A class I occlusion could be achieved in this case by removable and fixed orthodontic appliances combined with adjunctive treatment for the hypotonic orofacial musculature.
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Background: The long-term evidence regarding failures of fixed retainers is limited and the aim of this cohort study was to assess the long-term risk of failure of one type of maxillary and two types of mandibular fixed lingual retainers. Trial design: Retrospective cohort study. Methods: Eighty-eight patients in retention 10-15 years after orthodontic treatment were included. The type of failure; number of failures per tooth, per patient, and retainer; and adverse effects were assessed by (1) a questionnaire, (2) clinical examination, and (3) screening patients' clinical charts. Descriptive statistics were calculated and a Cox regression was used to assess possible predictors for mandibular retainer survival. Results and conclusions: In the mandible, 47 (53.4%) .016″ × .022″ braided stainless steel retainers (SS) were bonded to all six anterior teeth, and 41 (46.6%) .027″ β-titanium (TMA) retainers were bonded to the canines only. From the SS retainers 40.4% and of the TMA retainers 61% had no failures during the whole observation period. SS failures per retainer were 2.17 (3.15) vs. 0.66 (1.03) for TMA. The type of retainer was the only significant predictor for failure. In the maxilla, 82 (93.2%) .016″ × .022″ braided SS retainers were bonded to all four incisors and six retainers (6.8%) to all six anterior teeth. The latter group was not further analyzed due to the small sample size. From the retainers bonded to all four incisors, 74.4% had no failure during the whole observation period. SS average number of failures per retainer bonded to the four incisors was 1.14 (SD 2.93). Overall, detachments were the most frequent type of first failure followed by composite damage. From the original mandibular retainers 98.9% and of the original maxillary retainers 97.6% were still in situ 10-15 years after debonding. No adverse torque changes were observed. Limitations: Potential effects of selection bias, information bias, and attrition bias as well as possible confounding factors cannot be fully excluded in this study.
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Aims: To identify if lower incisor movements after orthodontic treatment are due to the relapse of the orthodontic treatment or due to natural growth. Subjects and methods: The subjects consisted of 92 patients who have had orthodontic treatment, divided into three groups, group 1: 38 individuals had no retainer in the lower jaw. Group 2: 24 individuals had a retainer 0.028 inch, a spring hard wire bonded to the mandibular canines only. Group 3: 30 individuals had a 0.0195-inch Twist-Flex wire, bonded to all mandibular incisors and canines. Study models before orthodontic treatment (T0), immediately after orthodontic treatment (T1), 6 years after orthodontic treatment (T2), and 12 years after orthodontic treatment (T3) were used for the measurements. The wires in groups 2 and 3 were removed after mean 2.6 years (SD 1.49). Little Irregularity Index (LII), inter-canine distance, available mandibular anterior space, and number of crowded incisors were registered. A Tooth Displacement Index (TDI) was developed to measure the tooth displacement directions at T0 and T3. Results: The LII showed equal values before treatment (T0) and at the follow-up registrations (T2 and T3). But about 25 per cent of the tooth displacements at T2 and T3 did not exist before treatment, at T0. This indicates usual growth changes and not relapse of the orthodontic treatment. Conclusion: As about 25 per cent of the displaced incisors can be considered as an effect of natural growth, not a relapse of the orthodontic treatment, it is valuable to use a displacement index in combination with other variables for investigations of stability after orthodontic treatment. Importance of the present study is that it is possible to differ between relapse and usual growth changes.
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Introduction: The aims of this study were to survey current retention procedures applied by Dutch orthodontists and to examine their acquaintance with "unintentionally active retainers." Methods: A questionnaire was sent to all 306 Dutch orthodontists involved in patient treatment. Questions were clustered in 4 parts: (1) general information, (2) retention procedures, (3) characteristics of wire materials for bonded retainers, and (4) acquaintance with "unintentionally active retainers." Results: The response rate was 98%. The most applied retention modality in the maxillary arch was a combination of a removable and a bonded retainer (54%); in the mandibular arch, mainly a bonded retainer without a removable retainer was used (83%). Bonded retention was aimed to be lifelong for the maxillary arch (90%) and the mandibular arch (92%). Mean removable retention duration was 2 years. Vacuum-formed retainers were used more frequently and Hawley-type retainers less frequently. The wire materials used for bonded retainers were diverse. All orthodontists were familiar with unintentionally active retainers; 44% believed this phenomenon is caused by the properties of round multistrand wires. The opinion that unwanted changes in tooth position can arise due to the properties of round multistrand wire material was associated with changing the wire material (P <0.005). Conclusions: Lifelong retention with bonded retainers continues to increase. All orthodontists were acquainted with unintentionally active retainers and their impact. There is a need to identify all causative factors of inadvertent tooth movement in relation to bonded retainers and to prevent the onset of unintentionally active retainers.
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As our understanding of orthodontic relapse has improved, there is an increasing move toward long-term retention. Safely reducing relapse using appropriate long-term retention imposes considerable responsibilities on the orthodontist, the patient, and the patient's general dentist. This article will describe these responsibilities.
Recent studies report widespread usage or exposure to a variety of chemicals with structural or functional similarity to bisphenol A (BPA), referred to as BPA analogues or derivatives. These have been detected in foodstuffs, house dust, environmental samples, human urine or blood, and consumer products. Compared to BPA, relatively little is known about potential toxicity of these compounds. This scoping review aimed to summarize the human, animal, and mechanistic toxicity data for 24 BPA analogues of emerging interest to research and regulatory communities. PubMed was searched from March 1, 2015 to January 5, 2019 and combined with the results obtained from literature searches conducted through March 23, 2015, in The National Toxicology Program’s Research Report 4 (NTP RR-04), “Biological Activity of Bisphenol A (BPA) Structural Analogues and Functional Alternatives”. Study details are presented in interactive displays using Tableau Public. In total, 5748 records were screened for inclusion. One hundred sixty seven studies were included from NTP RR-04 and 175 studies were included from the updated literature search through January 2019. In total, there are 22, 117, and 221 human epidemiological, experimental animal, or in vitro studies included. The most frequently studied BPA analogues are bisphenol S (BPS), bisphenol F (4,4-BPF), and bisphenol AF (BPAF). Notable changes in the literature since 2015 include the growing body of human epidemiological studies and in vivo studies conducted in zebrafish. Numerous new endpoints were also evaluated across all three evidence streams including diabetes, obesity, and oxidative stress. However, few studies have addressed endpoints such as neurodevelopmental outcomes or impacts on the developing mammary or prostate glands, which are known to be susceptible to disruption by BPA. Further, there remains a critical need for better exposure information in order to prioritize experimental studies. Moving forward, researchers should also ensure that full dose responses are performed for all main effects in order to support hazard and risk characterization efforts. The evidence gathered here suggests that hazard and risk characterizations should expand beyond BPA in order to consider BPA structural and functional analogues.
Introduction: The aim of this study was to evaluate and compare the clinical success of 2 lingual retainer wires. Methods: The 120 patients included in the study were divided into 2 groups randomly. In group 1, 0.0175-in 6-strand stainless steel wire (Ortho Technology, Lutz, Fla) was used, the lingual retainers were fabricated on plaster models, and a silicon transfer key was used. In group 2, 0.0195-in dead-soft coaxial wire (Respond; Ormco, Orange, Calif) was used, and the lingual retainers were fabricated directly in the patient's mandibular arch without a study model. Pretreatment, posttreatment, and posttreatment 3-month, 6-month, 9-month, and 12-month 3-dimensional orthodontic models were evaluated. Failure rates, mandibular arch irregularity values, intercanine distances, and arch lengths were compared. Results: The clinical bond failure rates were 13.2% for the 0.0175-in 6-strand stainless steel wire and 18.9% for the 0.0195-in dead-soft wire. The difference in bond failures between the 2 groups was not statistically significant. There was a statistically significant increase in mandibular arch irregularity in both groups during the 12-month follow-up. However, the increase was significantly higher in the second group than in the first one. Furthermore, the intercanine distance decreased over time in the second group. Conclusions: Our findings regarding mandibular arch measurements indicate that fabrication of lingual retainers can be more safely accomplished with 0.0175-in 6-strand stainless steel wire than with 0.0195-in dead-soft coaxial wire.
Background: There is a shortage of evidence on the best type of retainer. Objectives: Evaluate upper and lower bonded retainers (BRs) versus upper and lower vacuum-formed retainers (VFRs) over 12 months, in terms of stability, retainer survival, and patient satisfaction. Trial design: Two-arm parallel group multi-centre randomized controlled clinical trial. Methods: Sixty consecutive patients completing fixed appliance therapy and requiring retainers were recruited from 3 hospital departments. They were randomly allocated to either upper and lower labial segment BRs (n = 30) or upper and lower full-arch VFRs (n = 30). Primary outcome was stability. Secondary outcomes were retainer survival and patient satisfaction. A random sequence of treatment allocation was computer-generated and implemented by sealing in sequentially numbered opaque sealed envelopes independently prepared in advance. Patients, operators and outcome could not be blinded due to the nature of the intervention. Results: Thirty patients received BRs (median [Mdn] age 16 years, inter-quartile range [IQR] = 2) and 30 received VFRs (Mdn age 17 years, IQR = 4). Baseline characteristics were similar between groups. At 12 months, there were no statistically significant inter-group differences in post-treatment change of maxillary labial segment alignment (BR = 1.1 mm, IQR = 1.56, VFR = 0.76 mm, IQR = 1.55, P = 0.61); however, there was greater post-treatment change in the mandibular VFR group (BR = 0.77 mm, IQR = 1.46, VFR = 1.69mm, IQR = 2.00, P = 0.008). The difference in maxillary retainer survival rates were statistically non-significant, P = 0.34 (BR = 63.6%, 239.3 days, 95% confidence interval [CI] = 191.1-287.5, VFR = 73.3%, 311.1 days, 95% CI = 278.3-344.29). The mandibular BR had a lower survival rate (P = 0.01) at 12 months (BR = 50%, 239.3 days 95% CI = 191.1-287.5, VFR = 80%, 324.9 days 95% CI = 295.4-354.4). More subjects with VFRs reported discomfort (P = 0.002) and speech difficulties (P = 0.004) but found them easier to clean than those with BRs (P = 0.001). Limitations: Results are after 1 year and we do not know how much the removable retainers were worn. Conclusions: After 1 year, there is no evidence of a significant difference in stability or retainer survival in the maxilla. In the mandible, BRs are more effective at maintaining mandibular labial segment alignment, but have a higher failure rate. In comparison with patients wearing VFRs, patients wearing BRs reported that they caused less interference with speech, required less compliance to wear them, and were more comfortable to wear than VFRs. Patients found the BRs harder to keep clean. Trial registration: The trail was not registered.
Approximately 1/2 of maxillary and 1/5 of mandibular multi-stranded lingual retainers fail during retention in some form, either bond failure or wire breakage. Memotain is a new CAD/CAM fabricated lingual retainer wire made of custom-cut nickel-titanium, as an alternative to multi-stranded lingual retainers. It offers numerous perceived advantages to the traditional multi-stranded stainless steel wire, including precision fit, avoidance of interferences, corrosion resistance and even the potential for minor tooth movement as an active lingual retainer.