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progress in orthodontics 1 3 ( 2 0 1 2 ) 78–83

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Clinical contribution

Upper molar distalization on palatal miniscrews:an easy to manage palatal appliance

Luis Tomas Huanca Ghislanzonia,∗, Claudio Piepoli b

a PhD student, Department of Human Morphology, University of Milan, Italyb Orthodontic laboratory technician in Almenno San Bartolomeo, Bergamo, Italy

a r t i c l e i n f o

Article history:

Received 30 August 2011

Accepted 12 September 2011

Keywords:

a b s t r a c t

Upper molar distalization supported by miniscrews has become increasingly popular in the

last years. A detailed clinical and lab procedure for the realization of a distalization appliance

(fast back or distal jet) connected to miniscrews inserted in the anterior region of the palate is

presented. A case report illustrates the use of a fast back appliance supported by miniscrews

to correct the mesial shift of the molars and of the premolars as a consequence of an early

Implant-Supported

Orthodontic Anchorage Procedures

Orthodontic Appliance Design

Orthodontic Appliances

Tooth Movement

loss of the maxillary deciduous canines.

© 2012 Società Italiana di Ortodonzia SIDO. Published by Elsevier Srl. All rights reserved.

1. Introduction

The use of miniscrews as an aid in the distalization of theupper molars has become popular in the recent years1–11.Miniscrews has been placed in different sites in the max-illary bone according to the biomechanical system selectedfor distalization. Some Authors1,4,10 prefer to place TADs inthe interradicular space on the vestibular side of the maxillaand use miniscrews as indirect anchorage. A drawback of thisapproach is the poor quality of maxillary bone on the vestibu-lar side,12 with few ideal sites for miniscrew insertion.13

Furthermore, sooner or later throughout the therapy, minis-crews must be removed because they are “on the way” of teethmoving in a distal direction (usually premolars).

12,14

∗ Corresponding author. Department of Human Morphology, UniversE-mail address: [email protected] (L.T. Huanca Ghislanzoni).

1723-7785/$ – see front matter © 2012 Società Italiana di Ortodonzia SIdoi:10.1016/j.pio.2011.09.004

zone of the palate has been considered as ideal for miniscrewinsertion14. Some Authors3,7,9 inserted TADs in the intermax-illary suture while others at its side (2 to 3 mm of distance fromit)2,5,6,8. In growing patient where the midpalatal suture can bestill open15, a position close to the suture may be preferable.

The purpose of this paper is to describe the clinical man-agement of an effective distalization appliance (fast back ordistal jet) supported by miniscrew(s) inserted in the anteriorregion of the palate close to the the midpalatal suture. A casereport illustrates the use of the appliance to correct a mesialshift of the molars and premolars as a consequence of an earlyloss of the maxillary deciduous canines.

2. Clinical procedure

ity of Milan, Italy.

The clinical procedure is divided into two appointments. Dur-ing the first appointment the insertion of the miniscrews

DO. Published by Elsevier Srl. All rights reserved.

tics 1 3 ( 2 0 1 2 ) 78–83 79

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Fig. 1 – Possible configurations of the appliance: (A) Nancebutton with bilateral fast back, (B) Nance button withunilateral fast back, (C) Soldered stainless steel structure

progress in orthodon

s performed and a precise impression with polyvinylsilox-ne (PVS) is taken and sent to the technician. In the secondppointment the appliance is delivered to the patient andctivated.

The miniscrews used are 8 mm TADs (3 M Unitek, Monrovia,alifornia, USA). This system was chosen because of the-Cap, a hemispherical stainless steel structure with an

nner O-Ring that is easy to connect to the head of thecrew. This peculiar piece allows the technician to buildifferent structures as needed either by connecting the-Caps with a soldered stainless steel structure or by embed-ing them in a Nance button (Fig. 1). Since the O-Ring

s made of rubber it allows some insertion play betweenhe head of the minimplant and the O-Cap. This feature

akes the installation of the appliance easier regardless ofinor errors that may occur during the impression and lab

rocedures.

. First appointment – Insertion of theiniscrew(s)

ccording to the width of the palatal vault (a preliminaryransversal expansion may be needed) one or two miniscrews

ay be placed. Since it’s not clear in the literature whichs the affordable limit of force (1.5 to 2 N for 9 mm minis-rews when the force is applied transversal to the head ofhe miniscrews)16 it is preferable to place two miniscrews asnchorage whenever possible. When the palatal vault is hight may be preferable to place one single miniscrew as two

iniscrews would be too close to each other and it would bempossible to accommodate two O-Caps on the screw heads.y far, no problems were encountered on molar distalizationupported by a single screw.

Miniscrews should be placed 2-3 mm aside of the mid-alatal suture at the height of the contact point between therst and second premolars, roughly distally to the third palatalugae17 (Fig. 2). The direction of insertion should be parallel tohe sagittal plane, with a slight anterior inclination so that the

iniscrew is almost perpendicular to a plane tangent to thealatal vault at the insertion site (Fig. 3).

After insertion the clinician should check for primary sta-ility of the screws, since the impression procedure whichollows is quite demanding in terms of stress for the implants.f stability is poor a new screw can be placed a little anteriorr posterior to the failed one. If stability is good an O-Cap islaced on the head of each screw as shown in Figure 2. Whilelacing the O-Cap, it is important to safeguard the patient fromwallowing it by holding it with a stainless steel 0.010-inchigature.

. First appointment - Precision impression

he orthodontist could take advantage of the impressionaterials used by the prosthodontist. The author suggests a

PVS putty base is placed in the impression tray by the assis-ant while the orthodontist covers the O-Cap and the molarurfaces with a light body PVS impression material. The result

connecting the O-Caps with bilateral distal jet.

is an impression that is very precise in the palatal zone and inthe molar area, a factor that is critical for a good manufactur-

80 progress in orthodontics 1 3 ( 2 0 1 2 ) 78–83

Fig. 2 – Ideal insertion site of miniscrews (highlighted ingreen).

Fig. 4 – Optimal screw placement results in the O-Cap beingtotally embedded in the impression material (A). If theminiscrew is inserted too deep in the bone, the O-Caps maylay too superficial in the impression (B).

An optimal screw placement results in the O-Cap beingtotally embedded in the impression material. If the minis-crew is inserted too deep into the bone, the O-Cap may laytoo superficial in the impression (Fig. 4) and sometimes itmay remain in the mouth when the tray is removed. In thiscase the orthodontist should place the missing O-Cap in theimpression.

Finally a “courtesy” O-Cap should be placed on the head ofeach miniscrew so that the patient can feel more comfortablewhen swallowing or passing the tongue on the palatal vault.

5. Laboratory procedure

The technician must insert miniscrew analogues (or oldscrews) into the O-Cap and pour a stone model (Fig. 5). Fol-lowing the indication of the orthodontist the technician canvary the appliance design as already mentioned (Fig. 1). Beforesending the appliance back to the orthodontist, the O-Ringsshould be replaced with new ones because they are usually

Fig. 3 – Forward inclination of the miniscrew as seen byplacing a miniscrew into the O-Cap incorporated into theimpression (for demonstration purposes only).

6. Second appointment - Delivery of theappliance

The orthodontist should remove the “courtesy” O-Caps thatare in the patient mouth, taking care of ligating them to avoidaccidental swallowing. A rapid test of miniscrew stability isrecommended.

Appliance cementation is then similar to any other appli-ance with bands, with the exception of the palatal area wherea light pressure will be enough to let the O-Caps integratedinto the Nance button accommodate onto the miniscrewheads.

Activation of the distalization device (distal jet or fast back)should begin immediately with a moderate initial load. Dur-ing the subsequent appointments the orthodontist should

progress in orthodontics 1 3 ( 2 0 1 2 ) 78–83 81

Fig. 5 – The stone models are a precise reproduction of theminiscrew position (A) with the O-Cap acting as a“transfer” (B).

Fig. 6 – The one screw/fast back appliance: palatal view.The O-Ring should be replaced by the technician beforei

7

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Fig. 7 – Pre-treatment photographs: a mesial shift of themaxillary first permanent molars and deciduous molarsoccurred (A) together with the opening of spaces betweenthe incisors (B) as a consequence of early loss of thedeciduous canines.

Fig. 8 – Pre-treatment (A) and post-distalization

nsertion in the mouth.

. Case report

10-year-old patient presented with an early loss of theaxillary deciduous canines. As a consequence, the max-

llary permanent first molars and the deciduous molarsigrated mesially while the lateral incisors migrated distally

Fig. 7). The panoramic radiograph showed that the unerupted

(B) panoramic radiographs: the premolar-caninerelationship improved as a consequence of molardistalization.

82 progress in orthodontics

Fig. 9 – Superimposition on maxillary stable structuresshowing bodily distalization of the maxillary permanent

premolars followed the mesial shift of the deciduous molars,closing the space for the eruption of the permanent canines(Fig. 8). A one screw/bilateral fast back appliance was

Fig. 10 – Post-distalization photographs: spaces for theeruption of the permanent canines were restored (A) andan overcorrection of the molar relationship was achieved(B). Brackets were applied to distribute the spaces and tocorrect root inclinations.

r

1 3 ( 2 0 1 2 ) 78–83

the molar relationship was achieved. The post-distalizationpanoramic radiograph revealed the improvement in the incli-nations of premolars and canines (before bracket placement)and the spontaneous distalization of the second premolars(Fig. 8). A superimposition of the lateral cephalograms on themaxillary stable structures18 showed a bodily distalization ofthe permanent first molars (-3.1 mm) without vertical erup-tion (-0.4 mm) or side effects on the upper incisors (Fig. 9).Brackets were then applied to distribute the spaces and tocorrect root inclinations (especially second premolars) whilewaiting for spontaneous eruption of the permanent canines(Fig. 10).

8. Conflict of interest

The authors have reported no conflict of interest.

Riassunto

La distalizzazione dei molari superiori supportata da miniviti godedi una crescente popolarità negli ultimi anni. E’ presentata nel det-taglio una procedura clinica e di laboratorio per la realizzazione diun apparecchio di distalizzazione (fast back o distal jet) connessoa miniviti inserite nella regione anteriore del palato. Un case reportillustra l’utilizzo di un apparecchio fast back supportato da minivitiper correggere la deriva mesiale di molari e premolari in seguito allaperdita precoce dei canini decidui.

Résumé

Ces années-ci, la distalisation de la molaire supérieure à l’aide demini-vis a connu un essor de plus en plus important. Une procéduredétaillée clinique et de laboratoire est présentée pour la réalisationd’un appareil de distalisation (fast back ou bien distal jet) relié àdes minivis placées dans la partie antérieure du palais. Une étudede cas montre l’utilisation d’un appareil fast back soutenu par desmini-vis dans le but de corriger le déplacement mésial des molaires etdes prémolaires suite à une perte précoce des canines mandibulairestemporaires.

Resumen

En estos últimos anos, la distalización del molar superior con el aux-ilio de minitornillos se ha tornado cada vez más popular. Presentamosun procedimiento detallado clínico y de laboratorio para realizar unaparato de distalización (fast back o bien distal jet) conectado a min-itornillos, colocados en la región anterior del paladar. Un estudio decaso destaca el uso de un aparato fast back apoyado en minitornillospara corregir el desplazamiento mesial de los molares y los premo-lares a raíz de una pérdida temprana de los caninos mandibularestemporales.

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