Seminars in Orthodontics 31 (2025) 228−239

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Seminars in Orthodontics
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Purely bone-borne rapid palatal expansion with bracket plates and

replaceable expansion screw assembly
Yu Ri Kim a, Sung-Hoon Lim a,*, Seo-Rin Jeong a, Jae Hyun Park b,c
a
Department of Orthodontics, College of Dentistry, Chosun University, Gwangju, Korea
b
Arizona School of Dentistry & Oral Health, A.T. Still University, Mesa, AZ, USA
c
Graduate School of Dentistry, Kyung Hee University, Seoul, Korea

A R T I C L E I N F O A B S T R A C T

Tooth-bone-borne rapid palatal expansion (RPE) often results in unwanted buccal tipping of anchor teeth, particu-
larly in cases where midpalatal suture expansion is not successful. This report presents a novel approach to treat-
ing transverse maxillary deficiency through purely bone-borne RPE using bracket plates. The method involves
strategically placing four mini-implants in the palate before inserting the RPE screw. Subsequently, right and left
bracket plates are fixed over the mini-implant heads to connect two anteroposterior mini-implants. The RPE screw
is then attached to the bracket plates, securing the RPE connecting arms into 0.032 × 0.040-inch slot brackets on
the bracket plates. The primary advantage of this method is that the RPE screw is replaceable and adjustable. This
enhances the freedom in selecting mini-implant placement sites, ensuring better skeletal anchorage on the palatal
bone compared to tooth-bone-borne RPE, where mini-implant placement sites are limited to the periphery of the
RPE screw. This report presents two cases in which midpalatal suture expansion was successfully achieved using
purely bone-borne RPE without incurring any dental side effects.

Introduction Recently, miniscrew-assisted RPE (MARPE) or maxillary skeletal

expander (MSE) has become popular.14,15 These two appliances use
Transverse maxillary deficiency has been reported in 8-to-10 % of both mini-implant and tooth anchorages, so they can be called tooth-
adolescents and adults and is usually accompanied by unilateral or bilat- bone-borne RPE (TBBRPE) or hybrid-borne RPE. The typical MARPE
eral crossbite, a narrow nasal cavity, and crowding.1,2 Since its initial uses a Hyrax-type RPE screw with two-to-four mini-implants placed at
description by Angell3 in 1860, the rapid palatal expansion (RPE) proce- the holes on the anterior and posterior periphery of the RPE screw. To
dure has established itself as a well-regarded treatment option for cor- avoid dental side effects commonly seen with TBBRPE, various purely
recting maxillary transverse deficiency in adolescents.4 As RPE bone-borne palatal expanders (PBBRPE) have been introduced.16−21
treatment applies forces ranging from 15 to 50 N on the maxilla and par- Bone-borne expansion can result in greater transverse skeletal expansion
amaxillary structures, changes in other skeletal structures beyond the while reducing undesired dental side effects.22,23
maxilla are possible.4 Consequently, widening of the nasal cavity, In common TBBRPE, the RPE screw is placed with orthodontic bands
remodeling of the maxillary sinus, and changes in circumaxillary sutures on the first molars and first premolars, and then orthodontic mini-
have been reported after RPE treatment.5−9 implants are placed into the holes equipped at the anterior and posterior
Unfortunately, RPE using tooth-borne expanders can induce some periphery of the RPE screw. Therefore, there is not much freedom in
adverse effects including buccal tooth tipping, reduced buccal bone selecting mini-implant placement sites. The purpose of this report was
thickness, bone fenestration, buccal gingival recessions, bite opening, to illustrate a new PBBRPE assembly that consists of four palatal mini-
and root resorption.10,11 The problem can be especially pronounced in implants, two bracket plates connecting the mini-implants, and an RPE
older teenagers and adults where tooth-borne RPE might lead to den- screw that is placed on the bracket plates with connecting arms. The
toalveolar tipping that can cause unfavorable periodontal effects due to unique feature of this approach is that the RPE screw is placed after the
the interdigitated midpalatal suture and the decreased elasticity of placement of mini-implants, making the RPE screw semi-removable and
bone.12,13 adjustable. An RPE screw with connecting arms is fabricated in the

* Corresponding author at: Sung-Hoon Lim, Department of Orthodontics, College of Dentistry, Chosun University, 303, Pilmun-daero, Dong-gu, Gwangju 61453,
Korea.
E-mail address: shlim@chosun.ac.kr (S.-H. Lim).

https://doi.org/10.1053/j.sodo.2024.04.005

1073-8746/© 2024 Elsevier Inc. All rights reserved.

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Y.R. Kim et al. Seminars in Orthodontics 31 (2025) 228−239

laboratory and transferred to the patient by securing into the brackets on For PBBRPE, two 2.0 × 8 mm mini-implants were placed in the ante-
the bracket plates. The benefit of this approach is that the mini-implant rior paramedian area, and two 2.0 × 6 mm mini-implants were placed in
can be placed more freely because the RPE screw can be placed above the posterior paramedian area. Because the bone quantity and quality of
the bracket plates in a vertically overlapping manner. This approach the median area of the palate decreases posteriorly, mini-implants were
enables mini-implants to be placed at the palatal bone with better qual- placed as anteriorly as possible. The LIM plate system (Jeil Medical,
ity and quantity. Seoul, Korea) was used for this purpose, although the LIM plate system
is used mostly for maxillary molar distalization (Fig. 2).24−26 Then, two
bracket plates of the LIM plate system were placed over the platforms of
Case 1 the two anteroposterior mini-implant sets, and nuts were fastened to fix
the bracket plate to the mini-implant heads (Fig. 3, A). After scanning,
A 14-year-old female was referred to our department for the treat- the digital model was printed with a 3-dimensional printer (Fig. 3, B,
ment of palatal ectopic eruption of both maxillary lateral incisors and C). The two anterior arms of the RPE screw (Hyrax, Dentaurum,
(Fig. 1). She exhibited both posterior and anterior crossbite, maxillary Ispringen, Germany) were removed, and the two posterior arms were
and mandibular anterior crowding, and end-on Class II molar relation- ground to fit the slot size (0.032 × 0.040-inch) of the bracket on the
ship on the right side. The maxillary dental midline deviated to the right bracket plate (Fig. 3, C).
side causing lingual displacement of the maxillary right lateral incisor. The modified RPE screw was then secured into the brackets of the
Also, her maxillary incisor exposure was deficient both at rest and smil- two bracket plates using 0.012-in ligature wires, and the expansion
ing. The patient showed proper oral hygiene. However, there was an screw was activated until some resistance was felt during activation
occlusal caries at the mandibular right second molar. The panoramic (Fig. 3, D). This procedure was needed because there can be some play
radiograph showed relatively short roots on both right and left maxillary between the bracket and the RPE screw arms. Afterward, 0.8 mm expan-
central incisors, and all third molars were developing (Fig. 1). The ceph- sion was done by the orthodontist at 4-week interval visits. After four
alometric analysis revealed a skeletal Class III with a labioversion of the months of expansion, a periapical radiograph was taken on the maxillary
maxillary and mandibular incisors (Fig. 1 and Table 1). central incisors, and the midpalatal suture opening was observed
To correct the posterior crossbite and to relieve the crowding, (Fig. 4). At this time, a 1.0 mm thickness stainless steel (SS) wire lever
PBBRPE with the extraction of four first premolars was planned. After was inserted into the center hole of the RPE screw that receives the
bonding 0.022 × 0.028-inch slot preadjusted brackets on all teeth except expansion key for screw activation, and then fixed with a flowable com-
for the maxillary incisors, alignment was begun using nickel-titanium posite. An elastomeric chain was applied from the anterior right side of
(NiTi) archwires, bypassing the maxillary incisors. Subsequently, all first the transpalatal arch (TPA) to the lever on the expansion screw for molar
premolars were extracted.

Fig. 1. Pretreatment records of Case 1.

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Y.R. Kim et al. Seminars in Orthodontics 31 (2025) 228−239

Table 1
Cephalometric Measurements.

Measurement Norm ± SD Case 1 Case 2

Pretreatment Posttreatment Pretreatment Posttreatment

SNA (8) 81.1 ± 3.7 81.7 82.0 83.5 77.6

SNB (8) 78.0 ± 3.8 81.0 79.0 79.3 74.4
ANB (8) 3.5 ± 1.9 0.6* 3.0 4.1 3.2
Wits (mm) −2.7 ± 2.4 −6.0* −2.6 −0.1* −0.5
FMA (8) 29.6 ± 5.7 22.6* 19.0* 27.9 25.9
Occlusomandibular plane angle (8) 19.6 ± 3.7 16.1 14.9* 18.6 18.7
Occlusal plane to FH (8) 10.0 ± 2.0 6.5* 4.0* 9.3 7.1*
U1 to SN (8) 105.3 ± 6.6 112.3* 106.0 110.5 99.4
U1 to FH (8) 113.8 ± 6.4 123.7* 122.1* 118.1 114.2
IMPA (8) 91.6 ± 5.2 101.1* 90.1 93.2 94.1
IIA (8) 125.4 ± 9.2 112.6* 128.9 120.9 125.9

Note: Values are mean ± standard deviation.

* Difference more than one standard deviation.

distalization on the right side (Fig. 3, E). Brackets were bonded after
space was gained by molar distalization and PBBRPE (Fig. 3, F).
The activation took 13 months and was accompanied by fixed ortho-
dontic treatment. The RPE screw was activated to the full expansion
limit of 10 mm (Fig. 3, G). After the palatal expander was removed, a
0.032 × 0.032-inch SS (Burstone Transpalatal Arch SST, Ormco, Glen-
dora, CA) wire segment was placed on the brackets on the bracket plates
to maintain the suture expansion (Fig. 3, H).
Treatment was finished after 2 years and 9 months of treatment
Fig. 2. Components of the LIM plate system (Jeil medical, Seoul, Korea). Bolt-
(Fig. 5). The flat smile arc and lower lip protrusion were improved, and
headed mini-implant and nut assembly (A). A bracket plate is secured to the
platforms of the mini-implant heads using nuts (B)
the posterior and anterior crossbites were resolved. Cephalometric
superimposition showed that the mandible was rotated clockwise, but
this was beneficial in improving the skeletal Class III (Fig. 6). After one
year of retention, a normal buccal overjet was maintained, and also

Fig. 3. Bending the arms of a rapid palatal expansion (RPE) screw. Two bracket plates were placed over the four mini-implant heads (A). Digital model (B). The two
arms of an RPE screw were bent and ground down to 0.032 × 0.040-inch thickness to be placed into the bracket on the bracket plates (C). Four months of treatment
with 2.8 mm of expansion (D). At 8 months of treatment, molar distalization force was added on the right side (E). At 11 months of treatment, 7.4 mm of expansion
was achieved (F). At 19 months of treatment, RPE expansion was completed after 14 months of expansion (G). Then, the RPE screw was removed and a 0.032 × 0.032-
inch stainless steel wire with an expansion loop and posterior extension lever was secured to the two bracket plates (H).

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Fig. 4. A periapical radiograph at 8 months of treatment (A), and cone-beam computed tomography (CBCT) image at 14 months of treatment (B and C). The midpalatal
suture opening was observed in both images.

Fig. 5. Posttreatment records of Case 1.

bracket plates and two mini-implants were removed and a hypermentalis activity. Her chin was deviated to the left by 1.5 mm with
0.017 × 0.025-inch SS wire segment was placed between the remaining right-side down canting of the chin and occlusal plane. There was a
two mini-implants and fixed with nuts as a simpler retainer for the mid- 3.5 mm open bite with occlusal contacts only on her molars. Also, there
palatal suture expansion (Fig. 7). were 2.0 mm of Class II molar relationship on the right side, 2.5 mm of
Class II molar relationship on the left side, and anterior crowding. Ceph-
Case 2 alometric analysis showed a skeletal Class I (Fig. 8 and Table 1). The
lowered tongue posture was seen on the cephalogram, and she reported
A 13-year-old female presented with the chief complaint of not being having a mouth-breathing habit. The maxillary arch was narrower than
able to bite with her anterior teeth. She had a tongue-thrust habit and the mandibular arch due to the lowered tongue posture.
her tongue was positioned between her maxillary and mandibular inci- Although an extraction treatment was suggested, the parents opted
sors when at rest (Fig. 8). She had a convex facial profile and for non-extraction treatment which included rapid palatal expansion

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Y.R. Kim et al. Seminars in Orthodontics 31 (2025) 228−239

Fig. 6. Superimposition of pretreatment (blue) and posttreatment (red) lateral cephalometric radiographs of Case 1. Superimposition of pretreatment (yellow) and
posttreatment (blue) models. Anterior teeth were retracted into the premolar extraction spaces and the maxillary arch width was expanded, correcting the shallow buc-
cal overjet.

Fig. 7. Intraoral photographs after 1 year of retention in Case 1.

Two Bracket plates and two palatal mini-implants were removed
and a simple wire bar was fastened on the bolted heads of the two
remaining mini-implants with nuts.

with the space gained from the expansion to be used for the alignment. new 0.032 × 0.032-inch stainless steel wire segment with two poste-
Also, maxillary molar distalization was planned to correct the Class II rior extension levers was placed on the bracket plates for retention
molar relationships and to induce clockwise rotation of the maxillary of the skeletal expansion and also for maxillary molar intrusion
occlusal plane in the hope of closing the open bite. (Fig. 10, F). At this time, a 1.5 mm open bite remained after the
For PBBRPE, four 2.0 × 6 mm mini-implants were placed in the expansion and alignment. To intrude the maxillary posterior teeth,
palate (Fig. 9, A), and then an impression was taken for laboratory Damon brackets (Ormco) were bonded to the lingual surfaces of the
procedures. Two 0.032 × 0.032-inch stainless steel wire segments four maxillary premolars, and a 0.021 × 0.025-inch stainless steel
were bent to be placed into the brackets of the working model on TPA was engaged into these Damon brackets. Then, elastomeric
their apical ends while the opposite occlusal ends were positioned chains were applied from the brackets and sheaths on the lingual sur-
on the RPE screw, and then the wire segments were laser-welded to faces to the levers placed in the bracket plates to generate intrusive
the RPE screw (Fig. 9, B and C). At the next appointment, the forces (Fig. 10, G, and H). During treatment, the mandibular dental
0.032 × 0.032-inch stainless steel wire segment was ligated on the midline was deviated to the left. To correct this, a 2.5 × 14 mm
brackets on the bracket plates of her palate, and then the RPE screw mini-implant (JS, Jeil Medical) was placed after the extraction of the
was activated until some resistance was felt (Fig. 10, A). The RPE mandibular right third molar (Fig. 11, A). Then, distalization force
screw was activated 0.8 mm at each visit until sufficient buccal over- was applied from the mini-implant (Fig. 11, B, and C).
jet was achieved. After three months of treatment, simple tubes27 After two years and seven months of treatment, the treatment was
were bonded on both arches except for the maxillary second premo- finished. Maxillary and mandibular dental midlines coincided, normal
lars, where brackets were bonded. Simple tubes were chosen for overjet and overbite were achieved, and normal buccal overjet was also
their aesthetics and hygienic benefits.27,28 After full expansion to the achieved (Fig. 12). Expansion of the lateral wall of the nasal cavity, J
10 mm limit of the RPE screw, the RPE screw was removed, and a (jugular process) point, and alveolar bone were observed on the CBCT

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Fig. 8. Pretreatment records of Case 2.

Fig. 9. Modification of the RPE screw in Case 2. Mesial wings of the bracket plates were removed with a high-speed bur because the mini-implants were placed close
together to take advantage of the thicker bone near the midpalatal suture (A). Arms of the Hyrax screw were removed and 0.032 × 0.032-inch stainless steel wire seg-
ments were bent and then laser-welded to connect the bracket plate and RPE screw.

superimposition (Figs. 13-15, and Table 2). Furthermore, it was midpalatal suture.30 MARPE devices have shown a high success rate in
observed that the right maxillary first molar exhibited a decrease in maxillary skeletal expansion in late adolescents and young adults.31
molar inclination, and left maxillary first molar maintained its inclina- MARPE can produce midpalatal suture expansion with fewer dental side
tion, indicating that PBBRPE minimized the effect on teeth compared to effects and more orthopedic response than conventional RPE.22,32 How-
TBBRPE. ever, due to the limitations of the mini-implant anchorage for orthopedic
expansion and patient-specific limitations, successful suture expansion
Discussion cannot be guaranteed in older patients.33 When the midpalatal suture
expansion fails, severe dental side effects can occur when a TBBRPE is
In the two cases presented here, jaw growth during treatment was used. A finite-element analysis of a PBBRPE showed that stress was con-
minimal, indicating that the pubertal growth spurt had already passed centrated around the mini-implants and midpalatal suture.34,35 There
before the start of treatment. MARPE is recommended for patients who was no stress around the teeth. On the other hand, with TBBRPE and
have passed their pubertal growth spurt.29 Midpalatal suture expansion Hyrax-type arms on the first premolars and first molars, a large stresses
in older teenagers and adults is challenging due to the maturation of the developed not only in the midpalatal suture and mini-implants but also

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Y.R. Kim et al. Seminars in Orthodontics 31 (2025) 228−239

Fig. 10. Progress of treatment of Case 2. After 1 month of treatment (A), At 2 months of treatment, 5.8 mm activation of the RPE screw was achieved (B). At 4 months
of treatment, 6.8 mm of activation was achieved (C). At 6 months of treatment, a transpalatal arch was placed for molar distalization (D). At 8 months of treatment,
RPE expansion was completed to its full extent (E). A new 0.032 × 0.032-inch stainless steel lever was placed on the bracket plates for the retention of the expansion
and also for molar intrusion (F). Brackets were bonded on the lingual side of the four maxillary premolars, and a 0.021 × 0.025-inch stainless steel transpalatal arch
was engaged into these brackets. Then, elastomeric chains were applied from the TPA to the levers placed in the bracket plates to generate intrusive forces (G and H).
After completion of intrusion (I).

Fig. 11. A 2.5 × 14 mm mini-implant (JS, Jeil Medical) was placed in the extraction socket of the mandibular right third molar for the distalization of the mandibular
right dentition and midline correction in Case 2 (A). One week after mini-implant placement (B). After 2 months of mandibular total arch distalization (C to E).

in the roots of the anchorage teeth.34 From this perspective, PBBRPE can Quadexpander was introduced.16 With this appliance, the mini-implants
be a better treatment option, especially in skeletally mature patients in are placed with a surgical guide and then the customized expander is
whom the risk of suture separation failure is high. placed and connected to the mini-implants. This concept uses what is
In this aspect, various designs for PBBRPE were developed.16−21 The known as the ‘bone first principle,’38 offering greater freedom in the
mini-implants for most TBBRPE appliances are placed after the RPE selection of the mini-implant placement sites than with conventional
screw is placed. This results in the placement of the mini-implants at the TBBRPE, in which the mini-implant placement sites are predetermined
holes of the RPE screw periphery which often leads to the posterior by selecting the position of the TBBRPE appliance because the holes for
mini-implants being placed too posteriorly where the bone quality and mini-implant placement are equipped at the anterior and posterior
quantity are poor.36,37 In 2022, a PBBRPE appliance known as the periphery of the TBBRPE appliance. Although the Quadexpander

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Y.R. Kim et al. Seminars in Orthodontics 31 (2025) 228−239

Fig. 12. Posttreatment records of Case 2. Composite resin was

applied between the bracket plates to maintain the midpalatal
suture expansion.

provides more freedom in selecting the mini-implant sites compared to interlocking suture in older patients and achieve maximum orthopedic
typical TBBRPE, it still needs to be placed outside of the RPE screw expansion, the bicortical mini-implant anchorage is necessary.
because a vertical overlap of the RPE screw and the mini-implants is not In the present cases, only 6 or 8-mm-long mini-implants were placed.
allowed to secure the access space for the screw cap driver. In contrast, This is shorter than the mini-implants usually used in MARPE or bone-
the new approach shown here uses an assembly of bracket plates and an borne RPEs. Despite this short length, bicortical anchorage was achieved
RPE screw, thus overlapping of the two is allowed because the connect- without penetrating the nasal mucosa. This was possible because the
ing arms are tied on the brackets of the bracket plates. This increases the bracket plates were placed at the level of 1 - 2 mm distance from the pal-
freedom in selecting the mini-implant placement sites. Another benefit atal mucosa. In a typical TBBRPE, this distance is increased requiring
of this approach is that the corticopunture technique39,40 for releasing longer mini-implnat because the vertical position of the RPE screw with
the tight midpalatal suture can be applied more easily after temporarily holes for mini-implant is limited by the contact between the appliance
disassembling the RPE screw from the bracket plates. and the mucosa of the palatal vault. To prevent the perforation of the
PBBRPE depends more on skeletal anchorage than the TBBRPE does nasal mucosa, the thickness of the palatal bone should be measured to
because it uses no tooth anchorage. Therefore, achieving excellent bony select appropriate mini-implant length.
support is crucial to the success of the PBBRPE. For this, the “bone first” Another advantage of this approach is that the expansion can be
principle38 and the preferred T-zone20 can be utilized more freely with maintained by just connecting the two mini-implants after removing the
the new technique. Also, selecting patients with less ossification of the RPE screw and bracket plates. This is not feasible with typical TBBRPE
midpalatal suture is needed to lessen the burden of skeletal anchorage. appliances because the mini-implants must be removed first to remove
The degree of midpalatal suture ossification can be analyzed with CBCT, the RPE screw because the hole for the mini-implant placement is a part
especially for older adolescents and adults.41−43 Also, mini-implant sta- of the RPE screw. Another benefit of the present method is that the RPE
bility is essential for successful skeletal orthopedic expansion.44 Bicorti- screw can be replaced after its full expansion without having to replace
cal anchorage should be considered when heavy anchorage is required, the mini-implants. After the full expansion of the RPE screw, the con-
as it has been demonstrated to be biomechanically more favorable than necting arms of the RPE screw are untied from the brackets on the
monocortical anchorage for orthodontic tooth movement.45,46 Finite ele- bracket plates, and then an intraoral scan is done to fabricate new con-
ment analysis studies have reported that bicortical anchorages result in necting arms for the new RPE screw.
improved mini-implant stability, decreased mini-implant deformation The disadvantage of the present method is the difficulty in fabricat-
and fracture, more parallel expansion, and increased expansion during ing the connecting arms that are placed in the bracket slots of the
bone-borne palatal expansion.34,44,47 Therefore, to effectively split the bracket plate. Fortunately, this can be overcome by fabricating the

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Y.R. Kim et al. Seminars in Orthodontics 31 (2025) 228−239

Fig. 13. 3-dimensional superimposition of pretreatment (yellow) and posttreatment (blue) CBCTs of Case 2 showed expansion of the whole maxilla. The Cephalomet-
ric superimposition of pretreatment (blue) and posttreatment (red) showed 1 mm of mandibular growth. 3D superimposition of pretreatment (yellow) and posttreat-
ment (blue) digital models showed expansion of the maxillary arch.

Fig. 14. 3-dimensional superimposition showing buccal expansion in Case 2. 1.6 mm and 1.9 mm of expansion of the buccal alveolar bone was observed on the right
and left sides, respectively.

connecting arms with CAD/CAM or 3-dimensional printing technology. expansion (Table 2). This can be attributed to the flexibility of the con-
Another factor to be considered is the flexibility of the connecting arms necting arms. In the present cases, RPE screws were activated until some
that are placed in the bracket plate. Although 0.032 × 0.032-inch or resistance to the activation was felt on the day of placement. This was
thicker stainless steel connecting arms were used, the expansion necessary because the expansion force was transmitted through the con-
between the right and left mini-implants was about half the RPE screw necting arms.

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Y.R. Kim et al. Seminars in Orthodontics 31 (2025) 228−239

Fig. 15. Measurements of tooth inclinations as angles between tooth axis and the horizontal plane for both maxillary right and left first molars before expansion (left)
and after expansion (right).

Table 2 it is advisable to use 0.030-inch ligature wire. Double ligation can be

Expansion measurements between pretreatment and posttreatment. helpful although it is not needed routinely. During this procedure, the
ligature wire can be threaded under the bracket plate instead of relying
Measurement Case 1 Case 2
solely on the bracket wings.
The amount of buccal movement of the mesio-buccal Rt. +0.9 +1.2 A maxillary expansion rate of 0.8 mm per 4-week interval of the
cusp of the maxillary first molar (mm) Lt. −0.7 +2.6 present method represents a relatively slow skeletal expansion
Inter molar width (mm) Pre 51.1 48.9
speed,48 comparable to the rate of dental expansion achieved with
Post 51.3 52.7
The amount of buccal movement of alveolar bone in the Rt. -* +2.0 removable appliances. With conventional RPE, this slower expansion
maxillary first molar (mm) Lt. -* +2.5 rate may primarily result in dental expansion without significant
The amount of buccal movement of the mesio-buccal Rt. -* +1.6 skeletal expansion, as tooth movement can occur at this speed with-
apex of the maxillary first molar (mm) Lt. -* +2.4
out effectively transferring the expansion force to the midpalatal
The amount of buccal movement of J pointy (mm) Rt. -* +2.3
Lt. -* +2.1 suture. However, PBBRPE can still induce skeletal expansion even at
The amount of buccal movement of NC pointz (mm) Rt. -* +1.5 this slower rate due to its direct anchorage on the bone, bypassing
Lt. -* +1.5 the dental anchorage.
The amount of screw expansion (mm) +10.0 +10.0 The advantage of this gradual expansion is the prevention of
The amount of change between screws on the anterior part (mm) +6.8 +5.2
unsightly diastema formation during expansion, allowing for simulta-
The amount of change between screws on the posterior part (mm) +6.3 +4.9
neous orthodontic treatment for tooth alignment alongside RPE. While
* No pretreatment cone-beam computed tomography in case 1, so measure- this slower expansion may promote more physiologic expansion of the
ments unavailable.;. suture, it could extend the overall treatment duration. Further research
y
Jugular process;.
z is necessary to evaluate these aspects comprehensively.
Nasal cavity at widest point.

Conclusions
The presence of connecting arm between the RPE screw and the
bracket plates can be helpful for the fan-type expansion of the max- PBBRPE with bracket plates and RPE screw assembly offers a sig-
illa in the coronal plane with the center of rotation near the nasion. nificant advantage over TBBRPE due to its assembly sequence. In
Although a more parallel expansion was claimed as a benefit of the this new method, the RPE screw is installed after placing mini-
PBBRPE compared to the TBBRPE, this may increase the difficulty implants and bracket plates. This approach makes the RPE screw
of skeletal expansion because the separation of the sutures closer to replaceable and adjustable. This design increases the freedom in
the cranial base is more difficult. With bone-borne expansion, fan- selecting mini-implant placement sites, enabling the application of
type expansion may not cause buccal tipping of the posterior teeth the bone first principle. This improves the skeletal anchorage on the
because the teeth tend to be tipped lingually during PBBRPE as palatal bone compared to TBBRPE, where mini-implants are placed
opposed to the expansion with TBBRPE where buccal tipping of the at the RPE screw periphery after cementation of the RPE appliance.
anchor teeth for the RPE is inevitable. This new method may enhance the success of RPE treatment without
Another drawback of the current method is that securing the ligature incurring dental side effects.
tie on the connecting arm to the bracket plate can be challenging, espe-
cially when the RPE screw is positioned in such a way that it overlaps Patient consent
the bracket plates. Furthermore, the ligature ties may not be adequately
tight. To prevent slippage of the connecting arms during RPE activation, Consent was obtained from the parents of all two patients

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Y.R. Kim et al. Seminars in Orthodontics 31 (2025) 228−239

Funding expanders. J Orofac Orthop Fortschritte Kieferorthop€

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This study was supported by research funds from Chosun University Clin Orthod. 2012;46(10):608–612.
Dental Hospital, Korea, 2023. 18. Garib DG, Navarro RDL, Francischone CE, Oltramari PVP. Rapid maxillary expansion
using palatal implants. J Clin Orthod. 2008(11).
19. Kr€ usi M, Eliades T, Papageorgiou SN. Are there benefits from using bone-borne maxil-
Author contributions lary expansion instead of tooth-borne maxillary expansion? A systematic review with
meta-analysis. Prog Orthod. 2019;20(1):9. https://doi.org/10.1186/s40510-019-
0261-5.
All authors attest that they meet the current ICMJE criteria for 20. Wilmes B, DMD MSD, et al. The T-Zone: median vs. Paramedian Insertion of Palatal
Authorship. Mini Implants. J Clin Orthod JCO. 2016;L:545.
21. Aghazada H, Campobasso A, Annarumma F, Battista G. Design and manufacturing of a
fully digital boneborne palatal expander. J Clin Orthod JCO. 2023(10).
Declaration of competing interest 22. Lin L, Ahn HW, Kim SJ, Moon SC, Kim SH, Nelson G. Tooth-borne vs bone-borne rapid
maxillary expanders in late adolescence. Angle Orthod. 2014;85(2):253–262. https://
doi.org/10.2319/030514-156.1.
The authors declare the following financial interests/personal rela- 23. Tausche E, Hansen L, Schneider M, Harzer W. Bone-supported rapid maxillary expan-
tionships which may be considered as potential competing interests: sion with an implant-borne Hyrax screw: the Dresden Distractor. Orthod Francaise.
Sung-Hoon Lim reports financial support was provided by Chosun Uni- 2008;79(2):127–135. https://doi.org/10.1051/orthodfr:2008008.
24. Kim MS, Lim SH, Jeong SR, Park JH. Maxillary molar intrusion and transverse decom-
versity Dental Hospital. If there are other authors, they declare that they pensation to enable mandibular single-jaw surgery with rotational setback and trans-
have no known competing financial interests or personal relationships that verse shift for a patient with mandibular prognathism and asymmetry. Am J Orthod
could have appeared to influence the work reported in this paper. Dentofacial Orthop. 2020;157:818–831. https://doi.org/10.1016/j.ajodo.2019.02.022TagedAPTR-
AEnd.
The author (JP), serving as an editorial board member was not 25. Lim SH, Kim KB. Role of skeletal anchorage in modern orthodontics. Clinical Orthodon-
involved in the peer review or final decision-making process for the tics: Current Concepts, Goals, and Mechanics. 2nd ed. Elsevier Health Sciences;
manuscript. 2014:199–252.
26. Lim SH. Clinical application of palatal TADs. Temporary Anchorage Devices in Clinical
Orthodontics. John Wiley & Sons, Ltd; 2020:359–368. https://doi.org/10.1002/
Acknowledgments 9781119513636.ch36.
27. Jeong SR, Kim HI, Lim SH. Treatment of Class I crowding using simple tubes bonded
with customized resin coverings: a case report. Korean J Orthod. 2019;49(2):116–123.
There is nothing to declare. https://doi.org/10.4041/kjod.2019.49.2.116.
28. Zhu P, Lin H, Han Y, Lin Y, Xu Y, Zhang Z. A computational fluid dynamic analysis of
peri-bracket salivary flow influencing the microbial and periodontal parameters. PLoS
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