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Abstract:An increasingly number of patients with Angle Class II has been seeking orthodontic clinics to have their malocclusion treated.Herein, it is presented a new method of promote distal moviments in maxillary molars with a combination of limp-bumper (LB) and miniscrew. This technique was proven to be fast, practical and with low-cost, thus favoring both the professional and the patient. Keywords:Malocclusion, Angle Class II. Orthodontic Anchorage Procedures. Orthodontic Appliances. Tooth Movement.

ntroductionGiven the incessant pursuit of beauty imposed bythe current society, more and more people havebeen looking for orthodontic treatment. The

largest part of the population goes to orthodontic clinics dueto any visible dental or skeletal discrepancies1. Among them,Class II is found in a large group of individuals worldwide. Theprevalence of Class II varies greatly in Brazil, with an average of42%, considering its great territorial extension and considerablemiscegenation.2Such data highlight why professionals areconcerned to treat this type of malocclusion.1,3

The treatment scheme varies according to the etiology ofthe malocclusion and involvement of dental and/or skeletal

discrepancy.1,3-5The protocol for these patients consists ofdental extractions,1,3,4,6functional orthopedic appliances,1,3,4distalizers,1,3-7or orthodontic/surgery treatment.1,4In additionto the etiology, other important factors should be considered,such as age; growth period; patients psychological implications;financial condition; risks and damage to soft, dental andperiodontal tissues; patients compliance; treatment timing;among others1. The sum of all these aspects aware the professional andthe patient about the importance of performing a treatmentplan efficiently and in a shorter time1,3. The treatment protocolfor dental Class II malocclusion without significant skeletalinvolvement is limited to tooth extractions1,6or distalization.1,3,5-7

Extra or intraoral distalization is an excellent alternativefor the treatment of patients with dental Class II,1,3,4,7especially

when the severity of the malocclusion is lower than Class II.The use of extraoral appliances is the best option,1,3,7but dueto aesthetic standards imposed by society, these are not wellaccepted by the patient, making compliance more difficultand consequently leading to treatment failure.1,3,5,7Thus, analternative modality would be the use of intraoral appliances.1,4-7However, these type of appliances lead to some adverse effectssuch as protrusion of the incisors, mesialization of canines and

Distalization Controlled with the Use of Lip-bumper and Mini-screw

as Anchorage: A New Approach

By Tadeu Evandro Mendes Jnior, DDS; Anderson Barbosa Lima, DDS; Tadeu Evandro Mendes, DDS, MSc;Camila Vas Tostes Mendes, DDS; Henrique Damian Rosrio, DDS, MSc, PhD; Luiz Renato Paranhos, DDS, MSc,

PhD

FEATURE This article has been peer reviewed.

premolars, increased overjet, increased facial height, and distalinclination of the molars prolonging the treatment time.1,4,5,7

With the advent of mini-screws for temporary anchorage,a new concept of efficiency upon one of the big issues regardingintraoral distalization, was created.3,6Their widespread use is dueto the easy insertion and removal at various sites of the maxillaand mandible, with little damage to surrounding tissues, low-cost and immediate activation.3,6,8

Given the demand of patients for the treatment of ClassII malocclusion and the anxiety of getting effective treatmentin a short period of time, the aim of this study is to show thecombination of LB and mini-screw for distalization of uppermolars.

Case Report Male patient, aged 9 years and nine months, started histreatment presenting with acceptable facial asymmetry, opennasolabial angle and a little tendency to vertical growth (Figure1).

Figure 1 - A) Frontal photograph of the patient; B) Prole

photograph. Note the tendency to vertical growth and

convex prole.

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The intraoral examination revealed the presence ofdiastema, cross-bite and mixed dentition, moderate dentalcrowding, presence of the right first and second primary molarsin infra-occlusion, and Class II division 1 malocclusion (Figure2). After evaluating the panoramic radiographs and lateralteleradiograph (Figure 3), the patient was diagnosed withmandibular and maxillary retrusion, intruded upright upperincisors, retruded upright incisors, in addition to vertical growth

tendency (Table 1). Treatment options were given to the patient/guardian.The first one consisted of extracting two upper first premolars(14 and 24) due to the patients growth pattern with verticaltendency (SN.Gn 72; SN.GoMe 43). However, thisoption was declined by patients legal guardian. The second option, approved by the patients guardian,corresponded to distalization with the use of lip-bumper forthe maxillary dental arch and use of mini-screw as anchorage.

As such, the major goal of the treatment would be achieved -distalization of the upper molars toward the Class I position. The treatment involved several steps. Firstly, a Haasmodified expander was used to resolve the transversal issue. The

activation protocol proposed consisted of initial activation of4/4 turn (24 hours after installation). Then the legal guardian

was instructed to activate 2/4 turn daily for 5 days, as follows:1/4 turn in the morning and 1/4 turn in the evening. After 5days, the patient was requested to return to the office and anadditional activation of 4 days was recommended following thesame protocol. After transversal correction, the Haas appliance wasreplaced by a modified transpalatal bar with the purpose ofkeeping unaltered the transversal perimeter achieved with

Figure 2 - A) Baseline frontal intraoral photograph; B)

Baseline right-side intraoral photograph; C) Baseline left-

side intraoral photograph.

Figure 3 - A) Baseline lateral teleradiograph showing

a tendency to vertical growth; B) Baseline panoramicradiograph.

Figure 4 - A) Frontal photograph of the lip-bumper

immediately after installation of the mini-screw; B) Right-

side view showing the mini-screw between the molar

and premolar; C) Left-side view showing the mini-screw

between the molar and premolar.

Table 1 Simplifed Cephalometric Tracings

(Downs/Steiner) prior to treatment.Baseline Cephalometry - Simplifed

S.N. A 78.94

S.N. B 76.22

A.N.B 2.72

S.N. D 73.25

S.N.Gn 72.09

S.N.Ocl 17.13

S.N-Go.Me 43.44

1/.N.A 17.17

1/-N.A 3.19 mm

/1.N.B 16.00

/1-N.B 3.83 mm

1/1 144.10

IPMA 77.71

FMA 24.29

FMIA 78.00

H-nose 0.33 mm

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Figure 5 - A) Occlusal photograph after distalization; B)

Right-side periapical radiograph after distalization. Note

the increase of the distances between the roots; C) Left-

side periapical radiograph after distalization. Note the

increase of the distances between the roots.

Figure 6 A) Frontal photograph after distalization; B)

Right-side lateral photograph after distalization, with the

use of Class II elastics; C) Left-side lateral photograph

after distalization, with the use of Class II elastics.

Figure 7 - A) Frontal photograph of the patient; B) Frontal

smiling photograph C) Prole photograph.

Figure 8 - A) Final frontal photograph; B) Final right-side

lateral photograph; C) Final left-side lateral photograph.

the disjunction. Then, a fixed orthodontic appliance, Rothprescription (Morelli, Sorocaba, SP, Brazil), was installed foralignment and leveling. Some months later, the transpalatal bar was removed andthe following procedure was carried out under local anesthesia(2% lidocaine hydrochloride with 1:50,000 norepinephrine

hemi-tartrate): installation of 2 titanium mini-screws sizing1.5 mm diameter and 8 mm length on the buccal region ofthe alveolar bone and mesial region of the molars, which alsocorresponded to the distal region of the lower second premolars.Finally, a lip-bumper (LB) (Morelli) was set, supported by thefirst maxillary molars. In order for the patient to get acquainted, after two weeks,the LB was installed and activated with chain elastics (Morelli)

with force of 250 g each side.1,3,5-7The hook was linked to themini-screw, and distalization was made with the help of strengthof the upper lip9(Figure 4). For 3 months, distalization was checked using periapicalradiographs and photographs of the region of the molars.

Distalization occurred with translational movement and slightinclination which can be considered acceptable (Figure 5). After distalization, the LB and mini-screws were removed.The molar tooth was anchored with the aid of a Nance button,and retraction of anterior teeth was made using elastics for ClassII malocclusion (Figure 6). The treatment was finished with a class I molar and caninerelationship (Figures 7 and 8).

Discussion Despite this was a single clinical case, the use of a distalizerlip-bumper exceeded our initial expectations. It was a quickprocedure, and in only two appointments the mini-screws were

installed and the LB was made and activated. Although a minor surgical procedure is required forinstallation of mini-screws, no unusual event was reported bythe patient. A number of reports in the literature have shownthat the surgical procedure for installation and removal ofmini-screws is simple and brings no discomfort to the patientbefore or after surgery3,6,8. In addition, the mini-screws canbe removed from the original site of installation and replacedelsewhere to further favor distalization of the other teeth oranchorage of the distalized molar. Accordingly, mini-screwsare more advantageous than the procedure for installation

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of mini-plates8,10or osseointegrated implants,6,8which areusually reported as more invasive procedures, with significantpostoperative discomfort for the patient.6,8,10The latter requirea healing time of 3-6 months,6,8,10whereas mini-screws can beloaded immediately after installation, even though some authorshave indicated a 2-week waiting period prior to application ofthe load8. The laboratory phase for the preparation of the LB

was found to be advantageous as it is a simple device,9with

reduced cost when compared to other intraoral distalizationappliances.1,4,5,7Currently, some companies manufacture thiskind of prefabricated appliance, which implies that solely theability of the professional is required to adapt it in the sameappointment. In relation to the treatment time, only 3 months wereneeded using the distalizer LB to correct the relationshipof Angle Class II toward Class I with overcorrection. Thisreduction in the treatment time may be related to the mild (2-5g/cm2) and constant force of the upper lip,9when compared totraditional intraoral distalizers that take on average 4-7 monthsfor the correction.1,4-7

The use of nitinol open springs would be the option

of choice for distalization for presenting constant force.10

Nevertheless, due to injuries caused by the muscle pressure ofthe buccal mucosa, especially overnight, we opted for the useof chain elastics, and the intervals between appointments wereshortened though, which may have favored the distalizationtime.

Final Considerations Despite not having achieved an ideal distalization appliance,

we found that the LB combined with the use of a mini-screwproved to be a mechanical alternative to achieve the AngleClass I relationship, with very satisfactory results. The mainadvantages are the ease of installation and activation of all

components in a single appointment, and movement is achievedin a short period of time, although there is a little discomfortregarding the use of the LB.

References1. Pinzan-Vercelino CRM, Pinzan A, Janson G, Almeida RR, Henriques JFC,

Freitas MR. Comparison of the occlusal outcomes and the treatment timeof Class II malocclusion with the Pendulum appliance and with extractionof two maxillary premolars.Dental Press J Orthod2010; 15(1):89-100.

2. Freitas MRde, Freitas DSde, Pinheiro FHdeSL, Freitas KMSde. Prevalenceof Malocclusions in Patients Enrolled For Orthodontic Treatment in BauruDental School - USP. Rev Fac Odontol Bauru2002; 10(3):164-169.

3. Shimizu RH, Ambrosio AR, Shimizu IA, Godoy-Bezerra J, RIbeiro, JS,Staszak KR. Biomechanic principles of the headgear appliance. R DentalPress Ortop Facial 2004; 9(6):122-156.

4. Bassani M, Platcheck D. Mechanical alternatives to distalize molar teeth inpatients with class II malocclusion. Stomatos 2004; 10(18):21-28.

5. Bussick T, McNamara J. Dentoalveolar and skeletal changes associatedwith the pendulum appliance.Am J Orthod Dentofac Orthop 2000;7(3):333-343.

6. Gelgr EI, Bykyilmaz T, Karaman AIY, Dolanmaz D, Kalayci A.Intraosseous Screw-Supported Upper Molar Distalization.Angle Orthod2004; 74(6):838-850.

7. Ghosh J, Nanda RS. Evaluation of an intraoral maxillary molardistalization technique.Am J Orthod Dentofacial Orthop 1996; 110:639-46.

8. Nascimento MHA, Arajo TM, Bezerra F. Orthodontic micro-screws:installation and peri-implant hygienic orientation Orthodontic micro-

Dr. Tadeu Evandro Mendes Jnior is an OrthodonticSpecialist in Brazil INAPS - Varginha, MG,Brazil.

Dr. Anderson Barbosa Lima is an OrthodonticSpecialist in Brazil INAPS - Varginha, MG,Brazil.

Dr. Tadeu Evandro Mendes is an OrhtodonticSpecialist. He is professor of the INAPS, in Varginha,

MG, Brazil.

Dr. Camila Vas Tostes Mendes, works in a private clinic

in the city of Varginha, MG, Brazil.

Dr. Henrique Damian Rosrio is an OrthodonticSpecialist in Brazil. He is also a researcher in dentalmaterials. He addresses orthodontists on the futuretrends of orthodontics. He is an Orthodontics Professorin FUNORTE SC, Brazil.

Dr. Luiz Renato Paranhos is an Orthodontic Specialist

in Brazil. He has been published and has lecturednationally and internationally and is regarded as anexpert on facial morphology. He is a Professor in FederalUniversity of Sergipe - Department of Dentistry, SE,Brazil.

screws: installation and peri-implant hygienic orientation. R Clin OrtodonDental Press 2006; 5(1):24-31.

9. Hsler R, Ingervall B. The effect of maxillary lip bumper on toothpositions. Eur J Orthod2000; 22(1):25-32.

10. Nur M, Bayram M, Celikoglu M, Kilkis D, Pampu AA. Effects ofmaxillary molar distalization with Zygoma-Gear Appliance.Angle Orthod2012; 82(4):596-602.