orthodontic treatment of dental class ii with miniscrews ... · orthodontic treatment for dental...

Address for correspondence:

P PUJOLresidence Athenee36 avenue Georges Pompidou31270 [email protected]

DOI: 10.1051/odfen/2013107 J Dentofacial Anom Orthod 2013;16:206� RODF / EDP Sciences

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Orthodontic treatment of Dental Class IIwith miniscrews: an alternative toextraction of upper second molars

Pierre PUJOL

1 – INTRODUCTION

The treatment of severe dental class II byserial extraction of second molars (17-27-38-48) for hypodivergent patients still in thegrowth phase produces interesting estheticresults and at the same time respectsocclusal and orthodontic imperatives. Whenthe patient is still in the growth phase this isa very elegant solution that is contingentupon achieving good vertical control.

However this treatment strategy requiresexcellent cooperation from the patient in thewearing of extra-oral force headgear as wellas the extraction of upper second molars.

When miniscrews first became part of ourtherapeutic arsenal, their key advantages forthe treatment of antero-posterior discrepan-cies totally changed how we worked andexpanded the boundaries of our practice.

Therefore the final goals of treatmentremains identical but our clinical choicesare becoming easier and the extraction

of upper second molars are no longermandatory.

The first part of this article describes thedifferent stages of treatment for correction ofdental class II by using miniscrews, with adescription of the choice of the implant sitefor the miniscrews and of the technicaldetails for using and modifying the me-chanics during the different therapeuticstages.

In the second part of the article, two clinicalcases will demonstrate the effectiveness ofthis protocol for treatment. For these exam-ples, in each initial case, extraction of secondmolars with extra-oral headgear was thetherapeutic plan; and in each case, weswitched the protocol so as to conserve17-27 (and extraction of 18-28) by firstretracting the upper first molars that wasmade possible by the use of miniscrews foranchorage.

Article available at http://www.jdao-journal.org or http://dx.doi.org/10.1051/odfen/2013107

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2 – PROTOCOL FOR TREATMENT AND DIFFERENT THERAPEUTIC STAGES

The orthodontist achieves an essen-tial overall retraction of the arch entireby using miniscrews (posterior, lateraland anterior retraction).

A three stage strategy is required:– simultaneous retraction of the

posterior teeth (6-7) using direct me-chanical force;

– retraction of the buccal teethusing direct mechanical force for 5and indirect mechanical force for 3-4;

– retraction of the 4 upper incisorsusing direct mechanical force.

2 – 1 First stage:retraction of molars to class I(Fig. 1)

Position of the miniscrews

We use intraseptal miniscrews forantero-posterior discrepancies. If ana-tomical conditions allow it, it is prefer-able to place the miniscrew asanteriorly as possible in order to beable to move as many teeth aspossible in the mobilized area: the 7and the 6, and then the secondpremolars during the second stage.

The screw should be positioned be-tween the 4 and the 5.

Force modules

The active module is in the openposition, and here we see a com-pressed open spring placed betweenthe 6 and the 3 (5 and 4 are notbracketted so that they can be by-passed).

Anchorage for mobile elements

(direct mechanical force)

This is an offset system using ante-rior compressive force. The miniscrewis attached to a sliding hook (or directlyby a wire) that maintains anteriorcompression on the spring.

Mechanical analysis (Fig. 2)Despite the presence of extensive

open portions (spaces 3-6), we thinkof the system as a type of rigid slidingconnection because it uses a heavyarch wire (.017 · .025’’) in bracketswith .018 · .025’’ slots.

Figure 2 shows the mechanics ofsimultaneous retraction of 6-7 usingan open spring between 6 and 3,compressed by a tie connected to thescrew between 4 and 5. The metallictie ‘‘forces’’ the point of attachment to

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Figures 1a to 1cRetraction 6-7.

PIERRE PUJOL

2 Pujol P. Orthodontic treatment for Dental Class II with miniscrews: an alternative to extraction of upper second molars

distribute forces on a centered sphereat the screw and of a radius equal tothe length of the metallic tie. Thetension of the ligature, with a radialforce directed toward the screw willbalance any centrifugal radial force(unless it breaks). An analysis of themovement of the anchorage pointrequires the break down of the forcevectors of the force system into:

– a radial component Fr, incompa-tible with the connection;

– a tangential component (to thesphere) Ft compatible with the con-nection.

This Ft component must be brokedown into its forces vector to:

– an activation parallel to the arc Fhthat allows the point of anchorage toslide;

– a perpendicular activation to theFv arc that makes it possible to movethe entire arch (with a slight intrusionand counter clockwise rotation sincethe force is applied in front of thecenter of resistance of the arch),which is a useful movement in orderto correct a hypodivergent class II withoverbite.

2 – 2 Second stage: retractionof the premolars and thecanines to Class I

• Retraction 5 (Figs. 4 and 5)The 5 is for the most part often

retracted by transseptal fibers (Fig. 3),the position of the screws and themechanical system (anchorage andmodulation of force) are the same asthose mentioned previously (Figs. 4and 5) with direct mechanical force isdirect.

• Retraction 4-3 (Fig. 6)Position of the miniscrews (Fig. 7)The orthodontist moves the minis-

crew into the posterior area which isnow stabilized 7-6-5. The practitionernow places the miniscrew between 5and 6.

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Molar retraction, direct force analysis with rigid archwire, (mini)screw between 4-5

Legend:

Miniscrew

Center of resistanceRigid metal archwireCompressed open coilspring

Figure 2Mechanical analysis of the stage of molar retraction.

Figures 3a to 3cRetraction 6-7 to Class I after 4 months of therapy, partial retraction of the 5’s due to the trans-septal fibers.

ORTHODONTIC TREATMENT FOR DENTAL CLASS II WITH MINISCREWS: AN ALTERNATIVE TO EXTRACTION OF UPPER SECOND MOLARS

J Dentofacial Anom Orthod 2013;16:106. 3

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Figures 4a to 4cRetraction of the 5’s : intraoral views.

Retraction of second premolars, direct forceanalysis with rigid archwire (mini)screw between 4-5

Figure 5Mechanical analysis of the stage of retractionof the second premolars.

Figures 6a and 6bRetraction 3’s.

A miniscrew between the 5 & 6 and retied to the 5 by a steelligature, a Guerin Lock screwed-on at the mesial of the 6,crimped hook distal of the 2’s, the A-lastic chain from the 3’sto the mini-screws that are visible in the pictures.

Figures 7a to 7cAfter retraction to Class I of the 5’s-6’s-7’s the miniscrew is relocated distally between the 5-6.

PIERRE PUJOL


Force modules

We use active modules for spaceclosure, in this case, elastomericmodules.

Anchorage method on the stable

element (indirect mechanical force)

(Figs. 8 and 9)The orthodontist secures the screw

to the stable element by using a steelligature tied to the bracket of the 5.The need, even though the screws aresecured, to have a balanced relation-ship between moveable anchorageand stable anchorage will lead to theuse of remote groups of teeth forstable anchorage. During the premo-lar-molar retraction phase, as soon asthe 5 is sufficiently retracted, it isblocked by the screw. The gap of theretracted teeth in the upper anteriorsis closed (6 is blocked by a hook and 5by the screw). The arch is blockedanteriorly (by hooks crimped distally tothe 3s) and the stable anchoragegroup for the retraction of the succes-sive teeth becomes:

– for the 4: 3-2-1 plus 5-6-7 that arealready retracted and the supportscrew for anchorage;

– for the 3: 2-1 plus 4-5-6-7 that arealready retracted and the supportscrew for anchorage.

Mechanical analysis

(indirect mechanical force) (Figs. 8and 9)

The metallic ligature ‘‘forces’’ thepoint of attachment to move onto thecentered sphere using the screw andthe radius equal to the length to thesteel ligature. The tension on theligature, radial force directed towardsthe screw, will balance any centrifugalradial force (unless it breaks). Theanalysis of the movement of theanchorage point requires the breakdown of the force vectors of thesystem of forces into:

– a radial Fr component, incompa-tible with the connection;

– a tangential Ft component (tothe sphere), compatible with theconnection.

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Retraction of the first premolars, direct force analysis with rigid archwire (mini) screw between 5-6

Legend:HooksElastomeric modules

Figure 8Mechanical analysis of the step in the retraction of thefirst molars.

Canine retraction, indirect mechanical force with rigid archwire, (mini) screw between 5-6 steel ligature from 6-5-4.

Figure 9Mechanical analysis of the step in retraction of thecanines.



This Ft component must be brokendown into the force vectors of thesystem of forces:

– into a parallel action to the Fh arcwhich allows the stabilized group toslide along the arch;

– into an Fv perpendicular actionwhich mobilizes the entire arch (slightintrusion and practically no rotationsince Fv is applied to the center ofresistance of the arch).

Comment (Fig. 10)When the orthodontists succeed in

overcorrecting the premolar-molar oc-clusal relationship (7-6-5) in the firststages or in achieving anchoragepreparation on the lower jaw (byconventional mechanical force or with

miniscrews), they avoid moving themaxillary screws in the posterior area.The retraction of the anterior dentition(4-3 then 2-1) will be achieved eitherby reciprocal anchorage in the firstcase with an identical configuration tothe preceding one but without thesupport of miniscrews (Fig. 10) or byexerting Class II mechanical force inthe second case (on the preparedlower arch).

2 – 3 Third stage: retraction ofthe incisors (Fig. 11)

Position of the miniscrews

The screw stays positioned in thegaps 5-6.

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Figures 10a to 10cRetraction of the 3’s with reciprocal anchorage, hooks crimped mesial to the 6’s and distal to the 2’s.

Figures 11a to 11cRetraction of the maxillary incisors.

PIERRE PUJOL


Force modules

We use active module for closure(stretched closed coil helical springs).

Modality of anchorage on the

mobilized element (direct mechan-

ical force)

The tensioned closed coil springsare retied from the miniscrews tohooks soldered to the arch wire distalthe 3’s. This allows for modulation ofthe vertical force component in reg-ulating the respective attitudes of theminiscrew/anchorage on the arch.

The closed coil helical springs areapplied directly onto the mobile group.The F force is broken down into itsforce vectors of an Fh horizontal

component and an Fv vertical compo-nent. The Fh horizontal component iscompatible with the connection itcreates and it causes the intraarchmovement (closing of the ‘‘drawer’’).The Fv component is incompatible; itconflicts with the overall resistance ofthe arch that is globally subject to asmall intrusion along Fv and most ofthe time subject to a counter clock-wise rotation depending on the Fv.Bamoment.

The practitioner should note thatthere are several possible situationsbased on the site of the miniscrewsand of the height of the hook (Fig. 13).

4 – CLINICAL CASES

4 – 1 Case no 1: Jonathan(Figs. 14 to 24)

Jonathan comes in for a consulta-tion 03/27/2008 at the age of 11 yearsand 11 months.

• Clinical examination 03/27/2008

Extra-oral clinical examination

(Fig. 14)He presents with a gummy smile

and a harmonious a profile despite amarked labial-chin furrow.

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Retraction of maxillary incisors, sectional intra-arch sliding mechanics on a rigid arch wire).

Force applied directly to the moveable elementsFh: Horizontal component compatible with sliding mechanics It causes a pure translational movementIt pits the value of group anchorage against the resistance of the group to be movedFv: Vertical component incompatible with the linkupIt does not cause any movementIt pits the value of global resistance of the linkup, that is to say, the value of anchorage of the entire arch

Figure 12Mechanical analysis of the step of retraction of theincisors.

Maxillary incisor retraction, different situations encountered based on the height of the retraction hook

Schematization of different situations encountered with:-A situation based on MIA (low pull 5-6 mm) frequently encountered with a weak band of attached gingiva which determines essentially the situation wherein the resultant force is directed through the center of resistance of the arch for this type of traction -The height of the power arm (short arm 6 mm, medium arm 8 mm and long arm 10 mm)

Figure 13Mechanical analysis of the step of incisor retractionaccording to different situations encountered based onthe height of the retraction hooks.



Intra-oral clinical examination

(Fig. 15)The examination indicates a need

for improved hygiene. The molars andcanines are in a full Class II relation-ship. The overbite present from themixed dentition is significant. The 75is still present in the arch. We did notnotice any crowding in the lower jaw.

Panoramic x-ray examination

(Fig. 16)The examination does not reveal

any missing, supernumerary or trans-posed teeth. We did notice the pre-sence of the 45 under the 85. The fourwisdom teeth are present, the buds ofthe 38-48 are situated at the base ofthe ascending ramus.

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Figures 14a to 14cPortraits: profile, full face and smile at the start of treatment (03-08; 11 y 9 m).

Figures 15a to 15cIntra-oral views at the start of treatment (03-08; 11 y 9 m).

Figure 16Panoramic x-ray at the start oftreatment (03-08; 11 y 9 m).

Case No 1 : Jonathan

PIERRE PUJOL


Cephalometric examination

(Fig. 17)This examination makes it possible

to do a cephalometric analysis (Tab. I)and to calculate the objectives ofcephalometric treatment (Tab. IIa andIIb). The Tweed analysis of total spaceallows us to measure posterior crowd-ing (Tab. III).

• Synthesis of the diagnosis

Class II hypodivergent skeletalprofile.

Bimaxillary retrusion with overbite.

Severe dental Class II division 2.• Discussion and treatment plan

Choice of extraction and explana-

tion

Based on the Root Analysis Chart,treatment requires the extraction of17-27-38-48 and wearing an extra-oraldevice (headgear) for 18 months.Since the patient refused to wearheadgear, the orthodontist performeda therapeutic test using miniscrewsand anchorage was sufficient to avoidextraction of 17-27.

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Figures 17a and 17bTraced lateral cephalometric x-rayat the start of treatment (03-08; 11y 9 m).

Table ICephalometric analysis at the start of

treatment (March 3; 11 y 9 m).




Type of appliance

A Root pre-programmed maxillaryand mandibular multibracketted appli-ance.

Maxillary slot .018 · .024’’.Mandibular slot .022 · .025’’.• Results at the end of treatment

06/07/2010Treatment lasted 28 months.

Extra-oral photographs (Fig. 18)– The smile is harmonious.– The profile is balanced (Fig. 19)

and the conspicuous furrow line is nolonger present on the labial chin area.

Intra-oral photographs (Fig. 20)Dental hygiene has still not im-

proved. The occlusion achieved corre-sponds to the Andrews standards.

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Analysis Chart

1. Curve of Spee

2. Crowding

3. Reposition lower incisor

4. Molar mesialization

5. Reduction ANB (R/M)

6. Hyper/hyperdivergent

7. Palatal plane

8. Extraction delay

9. Value of extractions

10. Total

11. Net (severity factor)

12. T.I.M. Cl III/”j hooks”

13. F.E.O./ “j hooks”

Problem Ideal goal Treatment goal

Table IIa and IIbRoot Analysis, chevrons and ‘‘boxes’’ (March 3; 11 y 9 m).

Total space

analysis

Anterior

Middle

Posterior

Total dental deficit

CrowdingCorrection Ceph.

Soft tissueSub-totalCrowding

Curve of SpeeClass II

Sub-totalCrowdingGrowth

Sub-totalDental difficulty

0

0-3

-3

-3

-3

4

0

0

012

-2

1.5

1.5-1.5

1.5

0.515

4 41

13

-4

-18

/

/

Table IIITweed Analysis (total space) (March 3; 11 y 9 m).

PIERRE PUJOL



(Fig. 21)Root parallelism is satisfactory. The

eruption of the wisdom teeth will becarefully watched.

Cephalometrics and superimposi-

tions

Cephalometric analysis (Fig. 22,Tab. IV)

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Figures 18 a and 18bFull face and smile portraits at the end of treatment (07-10; 14 y 3 m)

Figure 19Profile change during treatment.

Figures 20a to 20cIntra-oral views at the end of treatment (07-10; 14 y 3 m).

Figure 21Panoramic x-ray at the end oftreatment (07-10; 14 y 3 m).




ANB diminished 2 degrees concur-rently with retraction of the incisors,the inter-incisal angle was notablyreduced going from 150 degrees to128 degrees.

General and local superimpositions(Figs. 23 and 24) reveal a significantcouter clockwise maxillary rotationwith a lesser clockwise mandibularrotation with retraction of 16-26 withcorrection of maxillary torque and aleveling of the deep overbite of the

maxillary incisors; note a repositioningof the lower incisors conforming to theobjectives of proper vestibular align-ment.

4 – 2 Case no 2: Louis(Figs. 25 to 35)

Louis comes in for a consultation on05/23/2007 at the age of 13 years and1 week.

• Clinical examination 05/23/2007

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Figures 22a and 22bTraced lateral cephalometric x-ray atthe end of treatment (07-10; 14 y3 m).

Figure 23General superimposition.

Figure 24Local superimposition of the maxilla and themandible.

Table IVCephalometric analysis at

the end of treatment(October 7; 14 y 10 m).

PIERRE PUJOL


Extraoral clinical examination

(Fig. 25)The examination shows a convex

profile with a retrognathic mandible.Intraoral clinical examination

(Fig. 26)

The examination indicates full ClassII molar and canine relationships. Theoverbite arising in the mixed dentitionis pronounced.


(Fig. 27)

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Figures 25 a to 25 cPortraits: Profile, full face and smile at the start of treatment (05-07 ; 13 y 0 m)

Figures 26a to 26cIntra-oral views a the start of treatment (05-07 ; 13 y 0 m).

Figure 27Panoramic x-ray at the start oftreatment (05-07; 13 y 0 m).Case N�2: Louis



This examination does not indicateany missing, supernumerary or trans-posed teeth. The four wisdom teethare present, the buds of 38-48 aresituated on the base of the ascendingramus.

Cephalometric examination

(Fig. 28)This examination allows us to per-

form a cephalometric analysis (Tab. V)and to calculate the objectives ofcephalometric treatment (Tab. VIaand VIb) and to calculate the extentof posterior crowding (Tab. VIII).

• Synthesis of the diagnosis

Class II hypodivergent skeletal pro-file.

Bimaxillary retrusion with overbite.Severe dental Class II division 2.• Discussion and treatment plan

Choice of extraction and justifica-

tion

As with the first clinical case, basedon the Root Analysis chart, treatmentshould begin with extraction of 17-27-38-48 and wearing of extra-oral force(headgear) for 1 year. The same

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Figures 28a and28bTraced lateral Cephalometric x-ray atthe start of treatment (05-05; 13 y0 m).

Table VCephalometic analysis at

the start of treatment(October 7: 13 y 0 m).

PIERRE PUJOL


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Analysis Chart

1. Curve of Spee

2. Crowding

3. Reposition lower incisor

4. Molar mesialization

5. Reduction ANB (R/M)

6. Hyper/hyperdivergent

7. Palatal plane

8. Extraction delay

9. Value of extractions

10. Total

11. Net (severity factor)

12. T.I.M. Cl III/”j hooks”

13. F.E.O./ “j hooks”

2

3

5

5

2

3

Problem Ideal goal

Table VIa and VIbRoot Analysis, chevrons and ‘‘boxes’’ (October 7; 13 y 0 m).

Totalspace

analysis

Anterior

Middle

Posterior

CrowdingCorrection Ceph.

Soft tissueSub-totalCrowding

Curve of SpeeClass II

Sub-totalCrowdingGrowth

Sub-total Total dental deficit

0

0

-3.2

-3.2/

1.51

11

0.5

0

0

3.2/

/

3.2

22

2

22

-2

-2

-1612-4 0.59.2 7.2Dental difficulty

Table VIITotal space analysis

Case N�2: Louis

Figures 29a and 29bFull face and smile portraits at the end of treatment (02-10; 15 y 9 m).

Figure 30Facial change during treatment.



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Figures 31a to 31cIntra-oral views at the end of treatment (02-10; 15 y 9 m).

Figure 32Panoramic x-ry at the end oftreatment (02-10; 15 y 9 m).

Case N�2: Louis

Figures 33a and 33bTraced lateral cephalometric x-rayat the end of treatment (02-10; 15 y9 m).

PIERRE PUJOL


therapeutic procedure was adopted inorder to avoid extraction of 17-27.

Type of appliance

A Root pre-programmed maxillaryand mandibular multibracketted appli-ance.

Maxillary slot .018 · .025’’.Mandibular slot .022 · .025’’.• Results at the end of treatment

02/16/2010Treatment lasted for 33 months

because the patient missed manyappointments.

Extraoral photographs

An examination of the face at theend of treatment shows a goodmandibular anterior rotation (Fig. 30).

Intraoral photographs

After removing the appliance, theocclusion is in Class I molar andcanine (Fig. 31), the arches are sym-metrical and the Curve of Spee isleveled.


(Fig. 32)The final panoramic x-ray objectively

demonstrated posterior crowding andtherefore justifies the extraction of18-28-38-48 at the end of treatment.

Cephalometrics and superimposi-

tions (Figs. 33 to 35)– Cephalometric analysis (Fig. 33,

Tab. VIII) shows normalizations of theANB angle and of the AoBo distanceresulting from the increase of the SNBangle, going from 75o to 80o. TheClass II improvement is especiallynoted on the upper incisors that gofrom 18o to 24o.

– The general and local super-

impositions (Figs. 34 and 35) showthe counter clockwise rotation of theupper jaw and especially of the lowerjaw that made it possible to avoidadversely impacting the profile of thepatient in spite of significant nasalgrowth.

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Table VIIICephalometric analysis at the endof treatment (October 2; 15 y9 m).

Figure 34General superimposition.

Figure 35Local superimposition of the maxilla and themandible.



5 - CONCLUSION

Using miniscrews for treating Den-tal Class II appears to be a remarkablenew tool since they can delay indica-tions for extraction and surgical deci-sions and at the same time reduce theneed for the cooperation of the pa-tient.

New standard protocols for correc-tion of Class II malocclusions thatinclude miniscrews have been intro-duced, implying that we must updateour skills with a new mechanical forcetechnique that is essential for morecomplex and notably a typical clinicaland therapeutic situations most nota-bly for atypical clinical situations.

The orthodontic discipline is con-stantly changing and we, the practi-t i one rs , can qu i ck l y becomeoverwhelmed and concerned by thissteady influx of information.

The profusion of new materials, ofnew technologies and of new instru-ments represents considerable pro-gress and obviously provides us withintellectual stimulation. However, acritical analysis of the mechanics ofminiscrews is a necessary ‘‘safe-guard’’ that should temper our clinicalobservations.

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PIERRE PUJOL


orthodontic treatment of dental class ii with miniscrews ... · orthodontic treatment for dental...

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