Treatment of Class III Malocclusions Using

Treatment of Class III Malocclusions UsingMiniplate and Mini-Implant AnchorageSeung-Hak Baek, Il-Hyung Yang, Keun-Woo Kim, and Hyo-Won Ahn

Orthodontic miniplates and mini-implants have become essential tools for

anchorage management. This article presents the treatment of growing Class

III patients with the use of the facemask in conjunction with the mini-plate

(FM/MP), and also the treatment of postadolescent Class III patients camou-

flaged by the use of mini-implants as skeletal anchorage. For FM/MP therapy,

an orthopedic force of more than 500 g per side with a vector of 30° downward

and forward from the occlusal plane was applied 12-14 hours per day after

placement of the curvilinear type surgical miniplates in the zygomatic buttress

areas of the maxilla. After 16 months of maxillary protraction, significant for-

ward displacement of the maxilla (point A) was found. Side effects of maxillary

protraction, such as labial tipping of the upper incisors, extrusion of the upper

molars, clockwise rotations of the mandibular plane, and bite opening, which

are usually observed using tooth-borne anchorage, were minimized. Therefore,

FM/MP can be an effective alternative treatment modality for maxillary hyp-

oplasia with minimal unwanted side effects. Class III patients in the postado-

lescent period can be camouflaged with fixed appliance by the use of mini-

implants as skeletal anchorage. The authors prefer to install the mini-implants in

the buccal attached gingiva between the upper second premolar and the first

molar. Class I intraarch elastics can be used to decompensate the already labially

inclined upper incisors. Class III interarch elastics can be used for distal en masse

movement of the lower dentition. Vertical elastics can be used to correct an open

bite problem if present. Extrusion or intrusion of the lower molars can be con-

trolled with strategic positioning of the mini-implants in the lower arch. With an

understanding of biomechanics, the careful use of miniplates and mini-implants

can expand the boundaries and scope of conventional fixed appliance therapy.

(Semin Orthod 2011;17:98-107.) © 2011 Elsevier Inc. All rights reserved.

desitp

Associate Professor, Department of Orthodontics, School of Den-tistry, Dental Research Institute, Seoul National University, Seoul,South Korea; Fellow Doctor and Graduate Student (PhD), Depart-ment of Orthodontics, School of Dentistry, Seoul National Univer-sity, Seoul, South Korea; Fellow Doctor and Graduate Student(PhD), Department of Orthodontics, School of Dentistry, Seoul Na-tional University, Seoul, South Korea; Resident and Graduate Stu-dent (PhD), Department of Orthodontics, School of Dentistry, SeoulNational University, Seoul, South Korea.

Address correspondence to Seung-Hak Baek, DDS, MSD, PhD,Associate Professor, Department of Oral and Maxillofacial Surgery,School of Dentistry, Dental Research Institute, Seoul National Uni-versity, Yeonkun-dong 28, Jongro-ku, Seoul, South Korea. E-mail:[email protected]

© 2011 Elsevier Inc. All rights reserved.1073-8746/11/1702-0$30.00/0

mdoi:10.1053/j.sodo.2010.12.003

98 Seminars in Orthodontics, Vol 17, N

Facemask in Conjunction withMiniplate as Skeletal Anchorage(FM/MP) Therapy for GrowingClass III Patients

The protraction facemask has been used tostimulate sutural growth at the circum-maxillary suture sites in growing Class III pa-tients with mild-to-moderate maxillary hyp-oplasia.1-3 However, the use of tooth-borne

evices as an anchor, such as palatal arches orxpansion appliances, can lead to unwantedide effects, such as labioversion of the upperncisors, extrusion of the upper molars, coun-erclockwise rotation of the upper occlusallane, and eventual clockwise rotation of the
andible.3-6
o 2 (June), 2011: pp 98-107

mailto:[email protected]

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99Class III Malocclusion and Miniplate/Mini-Implant

Placement of miniplates in the zygomatic but-tress area or other areas in the maxilla can trans-mit the orthopedic force to the maxilla directlyand minimize the rotational effect.7-11 Growing

atients with a Class III malocclusion and max-llary hypoplasia can be successfully treated withM/MP. The protocols of FM/MP are as follows:nder local anesthesia, a 1�2-cm horizontal ves-

ibular incision is made just below the zygomaticuttress area and the zygomatic buttress is ex-

Figure 1. Schematic drawing of installation and forcevector of the miniplate. (Courtesy of Professors BKCha and SM Kim.)

Figure 2. Initial records. (A) Facial photographs; (B)
version of figure is available online.)
osed with a subperiosteal flap. Curvilinear typeurgical miniplates (Martin, Tuttlinger, Ger-any) are bent to conform to the anatomical

hape of the zygomatic buttress. The bone of theygomatic buttress has sufficient thickness andone quality for attachment of the miniplates.12

Placement of miniplates in this area is close tothe center of resistance of the nasomaxillarycomplex so the force vector can be placed closeto the center of rotation of the nasomaxillarycomplex.7,13,14 The mesial end hole of the mini-plate was modified to the shape of a hook forattachment of elastics. After the miniplates are

aoral photographs; (C) Lateral cephalograms. (Color

able 1. Skeletal and Dental Measurements Beforend After Treatment

Initial Debonding

SNA 76.0 80.6SNB 81.4 77.7ANB �5.4 2.9A-N perp �3.4 2.2Pog-N perp 4.7 0.6FMA 32.7 37.0U1 to FH 123.14 119.48IMPA 88.2 76.3Interincisal angle 121.48 135.5

Intr

shed

100 Baek et al

placed into the zygomatic buttress areas, 3 self-tapping type screws per side are used to fix theminiplates. The mesial end of the miniplateshould be exposed through the attached gingivabetween the upper canine and the first premolar

Figure 3. Treatment progress. (A) After 15 months,placed. (C) Normal overbite and overjet were establi

Figure 4. Records at debonding. (A) Facial photograp
(Color version of figure is available online.)
to control the vector of elastic traction. Fourweeks after placement of the miniplates, themobility of the miniplates is checked and anorthopedic force of more than 500 g per sidewith a vector of 30° downward and forward from

overjet was decreased. (B) The fixed appliance was. (Color version of figure is available online.)

B) Intraoral photographs. (C) Lateral cephalograms.

the

hs. (

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the occlusal plane is applied for 12-14 hours perday (Fig 1). It is recommended to overcorrectthe malocclusion into a positive overjet andslight Class II canine and molar relationship.

Patients with cleft lip and or palate oftenpresent with a Class III malocclusions with max-illary hypoplasia. Scar tissue that develops aftercleft lip and palate surgery can disturb normalmaxillary growth. Because of hypoplasia of themaxillary and relative prognathism of the man-dible, treatment with conventional facemasktherapy might not achieve satisfactory results.15

The following Case 1 illustrates the treatment ofa cleft palate patient diagnosed with skeletal

Figure 5. Evaluation of the treatment changes. (A) Sateral cephalogram tracings (red in the online versionnd post-treatment. (Color version of figure is availab

Figure 6. Class III treatment mechanics using distalelastics and eventual counterclockwise rotation (flatt
available online.)
Class III malocclusion and an anterior open biteusing FM/MP.

Case 1

Diagnosis and Treatment Plan

Figure 2 shows a 12-year-old girl who presentedwith a history of a repaired cleft palate and askeletal Class III malocclusion. The patient pre-sented with a concave facial profile, an anteriorcrossbite, and an anterior open bite. The cervi-cal vertebrae maturation index showed a stage 4skeletal maturation, indicating that her skeletal

rimposition between pre- (black) and post-treatment) Comparison of soft tissue profile between pre-, mid-

nline.)

asse movement of the lower dentition with Class IIIg) of the occlusal plane. (Color version of figure is

upe). (B

en menin

tmastottsirtit

102 Baek et al

age was beyond her pubertal growth spurt.16

The cephalometric analysis showed a skeletalClass III open-bite tendency with a steep man-dibular plane angle. This hyperdivergent growthpattern contraindicated conventional facemasktherapy (Table 1). Although growth observationfor 2 years and then reassessment was proposedto the patient, the patient’s parents elected toreceive the FM/MP therapy.

Treatment Progress

FM/MP therapy was started 4 weeks after place-ment of the miniplates according to the proto-col advocated by the authors (Fig 3A). Duringprotraction, fixed appliances were placed toalign the dentition (Fig 3B, C).

Figure 7. Schematic drawing of Class III camouflageMini-implant anchorage in the upper arches and elamechanics without significant side effects. (B) Mini-imfirst molar and elastics produce intrusion of the lowplane. (C) Mini-implant anchorage in the retromola
molars and clockwise rotation of the occlusal plane. (Colo
Treatment Results

Figures 4 and 5 and Table 1 show the results ofreatment. There was significant forward move-

ent of the “A point” (A-N perp, 5.6 mm; ANBngle, 8.3°). Class II canine and molar relation-hips and normal overbite and overjet were ob-ained. A slight counterclockwise rotation of thecclusal plane angle occurred, indicating thathere was a minimal side effect of extrusion ofhe upper molars as evidenced by the tracinguperimpositions. Although the FMA angle wasncreased 4.3°, the anterior open bite was cor-ected by downward and forward movement ofhe maxilla. Slight lingual tipping of the upperncisors (U1-FH, 3.7°) occurred despite correc-ion of the anterior cross bite and open bite.

ment using mini-implant anchorage and elastics. (A)produce a similar result with conventional Class IIIt anchorage between the lower second premolar andolars and counterclockwise rotation of the occlusald area and elastics produce extrusion of the lower

treatsticsplaner mr pa

r version of figure is available online.)

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Ta


Treatment of Postadolescent Class IIIPatients by the Use of Fixed Appliancesin Conjunction with Mini-Implants asSkeletal Anchorage

Class III patients with mild-to-moderate skeletaldiscrepancies can be camouflaged by orthodontictooth movement. A half-step Class III molar rela-tionship could be corrected into a Class I molarrelationship by the use of distal en masse move-ment of the lower dentition with Class III elastics,counterclockwise rotation (flattening) of theocclusal plane, and dentoalveolar compensation(Fig 6).17-25 However, this treatment mechanics

as side effects, including labioversion of thepper incisors, extrusion of the upper molars,nd clockwise rotation of the mandible.

With recent development of mini-implant an-horage, the side effects of Class III camouflagereatment can be minimized.26,27 The authors pre-er to insert the mini-implants in the buccal at-ached gingiva between the upper second premo-ar and the first molar. Class I intraarch elastics cane used to decompensate the already labially in-lined upper incisors. Class III interarch elasticsan be used for distal en masse movement of theower dentition. Vertical elastics can be used to

Figure 8. Initial records (T0). (A) Facial photograph(Color version of figure is available online.)

orrect open bite problem if present (Fig 7A).

xtrusion or intrusion of the lower molars can beontrolled with strategic positioning of the mini-mplants in the lower arch (Fig 7B, C). The follow-ng Case 2 illustrates the camouflage treatment of

postadolescent Class III patient using fixed ap-liances in conjunction with mini-implants as skel-tal anchorage.

Case 2

Diagnosis and Treatment Plan

Figure 8 shows an 18-year-old female patientwho presented with lower anterior crowding,ectopic eruption of the upper second premolars,

). Intraoral photographs. (C) Lateral cephalograms.

able 2. Skeletal and Dental Measurements Beforend After Treatment

Initial Debonding

SNA 73.8 75.2SNB 73.5 73.6ANB 0.3 1.6A-N perp �2.0 �0.8Pog-N perp �0.1 �1.5FMA 27.1 27.2U1 to FH 117.3 114.2IMPA 83.0 82

s. (B

Interincisal angle 132.5 136.6

mag o

aaraoesaloCaty

104 Baek et al

protrusive lower lip, and mild skeletal Class IIIalocclusion. The cephalometric analysis showedskeletal Class III open bite tendency with lin-

ually inclined lower incisors (Table 2). Becausethe patient elected to receive a nonsurgical treat-ment option, the treatment plan was extractionof the upper second premolar teeth and Class IIIcamouflage treatment with fixed appliances us-ing mini-implants as skeletal anchorage.

Treatment Progress

After extraction of the upper second premolarteeth, leveling and alignment were started (Fig9A). At the end of leveling and alignment, therewas no significant aggravation of the overbiteand overjet while the lower anterior crowdingwas resolved (Fig 9B). At the 17th month oftreatment, 0.019 � 0.025 stainless-steel wireswere used in both arches. The mini-implantswere placed in the upper posterior area accord-ing to the protocol advocated by the authors andClass I intraarch elastics, Class III interarch elas-tics (1/4�, 6 oz) and anterior vertical elastics(3/16�, 6 oz) were used for key correction and

Figure 9. Treatment progress. (A) After extraction ofstarted. (B) After leveling and alignment, there was nThe mini-implants were installed in the upper arch andof figure is available online.)

occlusal settling (Fig 9C).

Treatment Results

Figures 10 and 11 and Table 2 show the resultsf treatment. After 25 months of fixed appli-nce treatment with mini-implants as skeletalnchorage, there was resolution of the ante-ior crowding, establishment of Class I caninend Class II molar relationship, and decreasef the lower lip protrusion. Significant distaln mass movement of the lower dentition re-ulted from mini-implants and Class III inter-rch elastics. Slight decompensation of theabially inclined upper incisors (U1-FH 3.0°)ccurred attributable to mini-implants andlass I intraarch elastics. Normal overbite waschieved by anterior vertical elastics. Thereatment results were well maintained after 1ear of retention (Fig 12).

Discussion

Advantages of FM/MP Therapy for GrowingClass III Patients

Because the miniplates are independent of the

pper second premolars, leveling and alignment werenificant aggravation of the overbite and overjet. (C)

ss (I) III and vertical elastics were used. (Color version

the uo sigCla

dentition, there are several advantages in FM/

line

cT


MP. Firstly, simultaneous orthodontic treat-ment and maxillary protraction using FM/MPis possible. Secondly, FM/MP can be used forrelatively longer periods than conventionalfacemask therapy and result in uniform ad-

Figure 10. Records at debonding (T1). (A) Faciacephalograms. (Color version of figure is available on

Figure 11. Evaluation of the treatment changes. (Aephalogram tracings (red in the online version). (B
0; Right: T1). (Color version of figure is available online
vancement of the maxilla during the entiretreatment period. Finally, MP/FM can mini-mize clockwise rotation of the mandible andprevent aggravation of the facial profile in thevertical growth pattern.

otographs. (B) Intraoral photographs. (C) Lateral.)

uperimposition between T0 (black) and T1 lateraltal en masse movement of the lower dentition (Left:

l ph

) S) Dis

.)

106 Baek et al

Advantages of Camouflage Treatment ofPostadolescent Class III Patients Using FixedAppliances in Conjunction with Mini-Implantsas Skeletal Anchorage

Insertion of mini-implants in the buccal at-tached gingiva between the upper second pre-molar and the first molar is relatively easier andshows a higher success rate than the lower pos-terior area.28

When Class III interarch elastics are used fordistal en masse movement of the lower denti-tion, the mini-implants inserted in the upperposterior area can decrease the side effects, suchas labioversion of the upper incisors, extrusionof the upper molars, counterclockwise rotationof the upper occlusal plane, and eventual clock-wise rotation of the mandible. In addition, ClassI intraarch elastics from the mini-implants in-serted in the upper area posterior to the upperarchwire can decompensate the already labiallyinclined upper incisors and decrease upper lipprotrusion and the nasolabial angle. This ClassIII mechanics with mini-implants can producebetter changes in the both the upper and lower

Figure 12. One-year retention records (T2). (A) Fa-cial photographs. (B) Intraoral photographs. (Colorversion of figure is available online.)

dentitions without significant side effects.

Conclusions

Careful use of miniplates and mini-implants to-gether with an understanding of the biome-chanical principals involved can expand theboundaries and scope of conventional fixed ap-pliance therapy.

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Treatment of Class III Malocclusions Using