CLINICAL CASE
Dent. Med. Probl. 2007, 44, 2, 275 280 � Copyright by Silesian Piasts University of Medicine in Wrocław
and Polish Stomatological Association
ISSN 1644-387X
JOANNA ANTOSZEWSKA
Class II Division 2 Treatment
Supported by Absolute Anchorage  Case Report
Leczenie klasy II grupy 2 wspomagane zakotwieniem absolutnym
 opis przypadku
Department of Dentofacial Orthopedics and Orthodontics, Silesian Piasts University of Medicine in Wrocław,
Poland
Abstract
The paper describes a case of class II/2 malocclusion efficiently treated with Absoanchor� system of microscrews
(1.2 diameter and 6 to 8 mm long) placed into alveolar bone and used as anchorage for incisor intrusion and for
class I reestablishment. The microscrew implants were maintained firmly throughout the therapy. Overbite decre-
ase and distalization proceeded with any of adverse reciprocal effects of conventional biomechanics such as: me-
sial molar or premolar tipping, premolar elongation or flaring of incisors. En masse distal movement of the whole
upper dental arch after anterior tooth alignment apparently reduced the active treatment into 12 months, thus ma-
ximizing the efficacy of the treatment. It may be concluded, that microimplants supporting class II/2 treatment are
promising and beneficial solutions for either clinicians or patients (Dent. Med. Probl. 2007, 44, 2, 275 280).
Key words: microscrew implants, orthodontics, class II division 2 malocclusion, non-extraction treatment.
Streszczenie
Opisano przypadek klasy II/2 leczony skutecznie za pomocą systemu Absoanchor�  śrub o średnicy 1,2 mm, dłu-
gości 6 8 mm, implantowanych w wyrostek zębodołowy i pełniących rolę zakotwienia w intruzji zębów siecznych
i odtwarzaniu klasy I. Mikrośruby były stabilne podczas całej terapii. Nagryz pionowy i dystalizacja przebiegły bez
widocznych skutków ubocznych konwencjonalnej biomechaniki, takich jak: mezjoinklinacja zębów trzonowych
lub przedtrzonowych, wydłużenie zębów przedtrzonowych lub wychylenie zębów siecznych. Dystalizacja en masse
wszystkich zębów górnych po uszeregowaniu zębów przednich pozwoliła wyraz
nie skrócić czas aktywnego lecze-
nia do 12 miesięcy, a tym samym maksymalnie je usprawnić. Można zatem twierdzić, że mikroimplanty wspoma-
gające leczenie klasy II/2 są obiecującym i korzystnym rozwiązaniem zarówno dla lekarza, jak i pacjenta (Dent.
Med. Probl. 2007, 44, 2, 275 280).
Słowa kluczowe: mikroimplanty, ortodoncja, klasa II grupa 2, leczenie nieekstrakcyjne.
According to orthodontic nomenclature, distal usually indicated as a non-extraction treatment ap-
position of first lower molars in relation to maxil- proach [1, 2]. The treatment of a class II malocc-
lary ones, accompanied by retrusion of upper inci- lusion without extraction requires posterior move-
sors is qualified as class II/2. This type of malocc- ment of the maxillary dentition, anterior move-
lusion may result from either skeletal abnormali- ment of the mandibular dentition, or a combination
ties and/or dento-alveolar discrepancies, which of both. Force moving molars backwards may have
determines selection of the treatment method. its fulcrum on patient s head and/or neck  when
Age, growth pattern, facial esthetics as well as a headgear is applied, or on premolars  when in-
arch-length deficiency should also be considered traoral distalizing devices are used. Nevertheless,
in the treatment planning. Therefore, in adole- disadvantages of these appliances have been widely
scents with class II/2 malocclusion coinciding discussed in the literature [3 9]. Efficiency of extra-
with moderate crowding (up to 9 mm) and arch- oral traction is basically dependent on patient s
-length deficiency, maxillary molar distalization is compliance, whereas intraoral approach shows
276 J. ANTOSZEWSKA
undesired mesial movement of anchoring teeth
and flaring of incisors. In addition, molars after di-
stalization are usually tipped distally, since the for-
ce vector passes by their centre of resistance.
Elimination of adverse changes on the reactive
part is possible due to fix, extradental anchorage
produced by titan orthodontic screws, temporarily
implanted in alveolar cortical bone. They do not re-
quire osseointegration, therefore may be loaded
immediately; force value must not exceed 400 G,
whereas 180 G per side is sufficient for en masse
retraction [10]. Evidence-based literature [11] pro-
ves that loading of microimplants (cross-sectional
1.3 mm or less) with distalizing forces applied ne-
ar the canine, are transmitted through dental con-
Fig. 1. Facial profile before treatment
tact points to the molars. Subsequently, the whole
dental arch freely moves backwards, since the li- Ryc. 1. Profil twarzy przed leczeniem
kelihood of root-microimplant-contact  certainly
limiting range of required distal displacement  is
diminished proportionally to screw-diameter de- was visible (Fig. 4), then lower round (0.016) Low
crease. Force� was inserted in 0.018 slots of brackets.
Among different orthodontic screw-systems 0.016 � 0.022 Low Force� and 0.018 stainless ste-
available on the Polish market only Absoanchor� el archwires respectively replaced the initial ones.
(produced by Dentos�, supplied by Orto Trading�) The next phase required implantation of two coni-
provides with tapered microimplants, therefore cal, 8-mm-long microscrews  1.2 diameter  into
their unique features were utilized in treatment of the vestibular, cortical bone, between roots of
presented class II/2 case. upper second premolar and first molar, on either
sides. All hitherto used microimplants were trea-
ted as self-tapping ones: vertical 4-mm-long inci-
Case Report sion of oral mucosa and preparation of an oblique
canal with a pilot-drill (Fig. 5) preceded screw
Patient L. S., 13-year-old, presented for ortho- tightening. Anatomy of the buccal alveolar surface
dontic treatment in December 2005. Her facial compelled vertical positioning of microimplants in
profile displayed skeletal class II relationship: the borderline between low and high position 
B line-crossing the base of the upper lip and the 5 mm above the archwire level. Consequently, the
chin was angulated distally in relation to A line- distalizing force passing beneath the center of re-
-crossing bases of the nose and the upper lip (Fig. 1). sistance of the frontal teeth could have possibly in-
Intraorally she had an Angle class II (Fig. 2a b) tensified initial retrusion of upper incisors. Such
and increased overbite (Fig. 2c). Cephalometric undesired phenomena was prevented by extra
analysis showed no significant abnormalities, elongated hooks bent on the basic, 0.016 � 0.022
except high value of ANB angle (5.1o)  skeletal stainless steel archwire. Nevertheless, hooks 10-mm
component of class II, and retruded upper incisors -long displayed high tendency to bend distally,
(1 + NA = 14o). Additional factors, such as young therefore  in order to keep them upright  a stabi-
patient s age and merely  2 mm of dentoalveolar lizing, passive sectional archwire was utilized
discrepancy  all together called for nonextraction (Fig. 6).
treatment. It started from banding and bonding of Lateral microimplants were loaded after 2 weeks
brackets with 0.018 slots in the upper arch; for le- of soft tissue healing; 8-mm-long closed coil-
veling 0.016 round NiTi archwire with minimum springs were stretched between screws and hooks
friction was applied (Low Force�, Forestadent�). thus generating 180 G of distalizing force. Special
At this stage, a 7-mm-long microscrew  1.2 dia- tiny holes in eye-lets of coil-springs (manufactu-
meter  was placed between central incisors, under red by Dentos�) enabled tightening them firmly to
the nasal spine, in medium position: 7 mm above microscrews (Fig. 7). Six months later, molar and
the archwire plane. Subsequently, upper incisors canine class I relationships on both sides were re-
were intruded with a force of 50 G generated by established (Fig. 8a b), upper and lower midlines
a rectangular elastic thread (Superthread�, Den- coincided (Fig. 8c).
tos�), extending from the microimplant to the ma- During finishing, for occlusion settling with-
in archwire (Fig. 3). After 8 weeks bite-opening out any side-effects on first lower molars, two mi-
Class II Division 2 Treatment by Absolute Anchorage
277
a b
Fig. 2. Dental casts before treatment:
a  right side, b  left side, c  en face
Ryc. 2. Modele przed leczeniem: a  strona prawa,
b  strona lewa, c  z przodu
c
Fig. 4. Treatment progress: apparent overbite decrease
Ryc. 4. Postęp leczenia: widoczne spłycenie nagryzu
pionowego
Discussion
Conventional consecutive distal movement of
Fig. 3. Scheme of Superthread� (0 attached to main
>)
archwire and passing through the hole in the head of teeth, despite of its effectiveness, still brings a cer-
screw ( ), thus loading the microimplant
tain amount of anterior anchorage loss  mesial
Ryc. 3. Schemat nici Superthread� (0>) dowiązanej do movement of premolars contributes 20 to 40% of
łuku podstawowego i przechodzącej przez otwór
the space created during distalization of molars;
w główce śruby ( ), obciążającej w ten sposób mikro-
furthermore distal tipping of the latter ones (rang-
implant
ing from 4 to 14o) also becomes evident in routine
biomechanics [12, 13]. Intra-arch devices, such as
Keles Slider with NiTi coil-spring [14] or lingual
croscrews were implanted buccaly between roots NiTi coil [15] successfully overcame the problem
of first and second molars, on either sides of the of molar tipping, nevertheless both still provided
mandible. Implantation technique, suitable for movement of single teeth against the device rather
self-tapping screws, resembled one applied in the than simultaneous retraction of the whole denti-
maxilla. Two weeks later, microimplants were tion.
loaded with 150 G of force per side, generated by Search for stationary absolute anchorage have
ź medium elastics (Fig. 9) displacing whole man- demonstrated that implants utilized in prosthetics
dible forward; finishing phase is still in progress. were also applicable for orthodontic purposes. Pa-
latal implants supporting modified Distal Jet [16]
278 J. ANTOSZEWSKA
a
Fig. 5. Scheme of pilot drilling and angulation
of the canal for microscrew-implant
Ryc. 5. Schemat prowadzenia wiertła pilotowego i na-
chylenia kanału dla mikrośruby
b
Fig. 6. Segmented archwire keeping hooks upright.
Noticeable symptoms of improper oral hygiene requi-
c
red professional re-training and plaque removal
Fig. 8. Intraoral pictures after 12 months of treatment:
Ryc. 6. A
uk odcinkowy pionizujący haczyki. Wyraz
ne
a  right side, b  left side, c  en face
symptomy niewłaściwej higieny wymagały ponowne-
Ryc. 8. Zdjęcia wewnątrzustne po 12 miesiącach
go profesjonalnego instruktażu i usunięcia złogów na-
leczenia: a  strona prawa, b  strona lewa,
zębnych
c  z przodu
Fig. 9. Class II elastics stretched between lower mi-
croscrew and hook of the canine-bracket, stabilizing
reestablished class I
Ryc. 9. Wyciągi klasy II rozpięte między dolną mikro-
śrubą i haczykiem zamka na kle, stabilizujące odtwo-
rzoną klasę I
or Pendulum appliances [17], turned out to be re-
Fig. 7. Scheme of biomechanics applied for class II/2
sistant against 250 G of distalizing force absolute-
treatment. Symbols:  center of resistance,
ly adequate to provide en masse retraction. How-
 head of microimplants,  closed coil spring,
ever, high cost, limited number of implantation
 eyelet. Line displays archwire with the
areas and necessity of delayed loading result in
customized hook
cortical screws privilege over endosseous choice.
Ryc. 7. Schemat biomechaniki zastosowanej w lecze-
Sliding mechanics with the aid of the micro-
niu klasy II/2. Oznaczenia:  centrum oporu,
 główka mikroimplantu,  zwój sprężyny screw implant anchorage (MIA) and its applica-
zamkniętej,  zaczep oczkowy. Linia oznacza łuk
tion for nonextraction treatment has not been wi-
podstawowy z indywidualnie dogiętym haczykiem
dely discussed, although since screws have been
Class II Division 2 Treatment by Absolute Anchorage
279
introduced in clinical orthodontics [18] these pre- lute anchorage against which posterior teeth could
sented the clinician with a versatile option. The be retracted as a unit shorten treatment time due to
use of microscrews in the case reported enabled en group movement of teeth, not to rapid tooth move-
masse retraction of teeth, without any reciprocal ment possibly increasing risk of root resorption. It
effect on the anchored unit; screws remained sta- was also true in the presented case were en masse
ble and did not show any mobility throughout the retraction of the whole dentition was achieved
treatment. Choice of self-tapping method of im- after 6 months. Relation of microscrew to the
plantation could have possibly been crucial for crown of the second premolar (Fig. 8a) displayed
firm fixation of screws: incision of gingiva and pi- efficiency and range of distal movement of the
lot drilling prohibited either dragging of soft tissue upper teeth. Buccal crown torque and buccal fla-
into screw-canal or excessive pressure during ring bend prevented against undesired lingual tip-
screw tightening. By placing microscrew implants ping and distal rotation reported in the literature
at 30 40o to the long axes of the crowns, the api- [20] as the side effects of a distalizing force ap-
ces of the microscrew implants were kept apart plied on the vestibular side.
from the roots. Therefore, the possibility of dama- The author conclude that efficient distal move-
ge to the roots was eliminated as well as a chance ment of upper molars is difficult to achieve co-
that the roots of the teeth might have touched mi- nventionally, since routine biomechanics enforces
croscrew implants during retraction. The occlusal- either adverse anchorage loss or uncontrolled mo-
-gingival height of the microimplants and position lar rotation and tipping. Furthermore, there is no
of the customized hooks together determined the possibility to obtain dental unit withstanding si-
direction of the line of force relative to the center multaneous retraction of all teeth, so class II divi-
of resistance, thus permitting predictable biome- sion 2 treatment requires several, time-consuming
chanical control of the movements. The contact on phases of distalization.
the crowns of teeth acted as a resistance to move- Ability to provide absolute anchorage for the
ment, which created a counterclockwise moment en masse distal bodily movement not only counte-
on the anterior teeth, resulting in their distal dis- racts undesired movement but shortens the treat-
placement and proclination favorable in class II di- ment time distinctly, therefore nonextraction treat-
vision 2 treatment. ment supported by the microscrew implants is be-
Park [19] proved that ability to produce abso- neficial for both clinicians and patients.
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Address for correspondence:
Joanna Antoszewska
Department of Dentofacial Orthopedics and Orthodontics
Silesian Piasts University of Medicine
Krakowska 26
50-425 Wrocław
Poland
Tel.: [phone]
E-mail: [e-mail]
Received: 10.01.2007
Revised: 26.03.2007
Accepted: 31.05.2007
Praca wpłynęła do Redakcji: 10.01.2007 r.
Po recenzji: 26.03.2007 r.
Zaakceptowano do druku: 31.05.2007 r.