Journal ofOrthodontîcZ^ol 40, 2013, 256-263 !

CLINICALSECTION

Skeletal class III maloeclusion treatedusing a non-surgieal approachsupplemented with mini-implants: acase reportMarcel Marchiori Farret^ and Milton M. Benitez Farret^'Private Practice, Brazil; ^Department of Orthodontics, Federal University of Santa Maria, RS, Brazil

We describe a 28-year-old man who sought orthodontic treatment complainitig about the esthetics of his smile and difficulties |associated with masticatory function. The patient had a straight facial profile, skeletal atid dental class III relationship, |anterior open bite and posterior crossbite. He refused orthognathic surgery and was therefore treated with camouflage iorthodontics supplemented with the placement of one mini-implant in each side of the mandible to facilitate movement of the 'lower dentition distally, tooth-by-tooth. At the end of treatment, a class I molar relationship was obtained, with an idealoverjet and overbite and excellent intercuspation. Furthermore, the open bite and crossbite were corrected. Analysis 2 yearsafter treatment revealed good stability of treatment outcome.

Key words: Class III maloeclusion, non-surgical treatment, mini-implants

Received 23 October 2012: accepted 27 January 2013

IntroductionAn Angle class III maloeclusion has a low incidenceamong patients who seek orthodontic treatment inWestern countries.' However, these few cases canrepresent the greatest challenge for the orthodontist,because of the complexity of treatment and high tendencyfor relapse.^ When associated with skeletal features, aclass III maloeclusion becomes more difficult to treat.^Severe skeletal discrepancies in adults usually requireorthodontic treatment and orthognathic surgery; how-ever, mild-to-moderate discrepancies can sometimes becompensated using non-surgical orthodontic treatmentalone.''^^ In this context, skeletal anchorage with mini-plates or mini-implants has improved the success ofcompensating treatments.^'^^' Mini-plates are the moreinvasive option, and are required when large discrepan-cies are diagnosed and therefore, greater dental adjust-ments are needed and more anchorage is necessary.^'^''°Mini-implants are less invasive for skeletal anchorage andmay be used for mild discrepancies; they are thetreatment of choice when movements will be small orwhen the patient refuses mini-plates owing to the extentof the surgical procedure.^'""'^ This manuscriptdescribes the treatment of a 28-year-old man with a

Address for correspondence: M. M. Farret, 1000/113 FlorianoPeixoto St, Santa Maria, RS 97015370, Brazil.Email; marcelfarret@yahoo.com.br© 2013 British Orthodontic Society

skeletal class III maloeclusion associated with anterioropen bite and posterior crossbite, treated by orthodonticcamouñage with one mini-implant placed in each side ofthe mandible.

Case report

Facial analysis revealed that the patient had a straightprofile; the lower facial third was enlarged and smileesthetics was impaired because of the class III relation-ship and anterior open bite (Figure 1). Intraoral analysisrevealed a class III maloeclusion, anterior open bite,posterior crossbite on the left side, a slight deviation ofthe upper midline to the right and mild crowding of theanterior region in the lower arch (Figure 2). Panoramicradiography showed good parallelism among the rootsand small roots associated with the lower secondpremolars, while cephalometric analysis confirmed theskeletal class III maloeclusion and accentuated loweranterior facial height (Figure 3).

Treatment objectives were to achieve class I molar andcanine relationships, eliminate the posterior crossbiteand anterior open bite and establish and ideal overjetand overbite. The facial appearance should be improvedbecause of the retraction of the lower incisors and

DOI 10.1179/1465313313Y.0000000046

JO September 2013 Clinical Section Class III malocclusion treated with mini-implants 257

Figure 1 Pre-treatment extra-oral facial photographs

elimination of the crossbite and edge-to-edge posteriorrelationship, producing a counterclockwise rotation ofthe mandible. However, this was largely a secondaryobjective of treatment because the patient elected toavoid orthognathic surgery and had no major com-plaints about his facial appearance.

A number of treatment options were consideredfor this patient. The first was a combined orthodontic-surgical approach with maxillary advancement, pos-terior impaction and mandibular counterclockwiserotation to close the open bite and reduce the LAFH.Orthognathic surgery was rejected by the patient. The

Figure 2 Pre-treatment intra-oral photographs

7O September 2013

Figure 3 Pre-treatment panoramic and cephalometric radiographs

Figure 4 Treatment progress. Folowing implant placement, the lower second molars have been moved distally before lower first molardistal movement

JO September 2013 Clinical Section Class III malocclusion treated with mini-implants 2591

L J

Figure 5 Post-treatment extra- and intra-oral photographs

second option was a non-surgical approach usingelastics and a sliding jig on the lower arch to obtaindistal movement of the lower dentition, tooth-by-tooth.This option was considered disadvantageous because ofthe possibility of upper molar extrusion using the classIII elastics, increasing the LAFH and impairing closureof the anterior open bite; consequently, this option wasalso disregarded. A third option considered extractionof a lower incisor to provide space for lower incisorretraction and orthodontic camouflage. The finaloption, involved the use of mini-implants in the lowerarch to provide anchorage for moving the lower teethdistally, avoiding the collateral effects of elastics andinvasive procedures such as the orthognatic surgery.

extractions or mini-plate insertion. It was decided toproceed with this treatment plan.

Initially, 0.022 x 0.028-inch standard edgewise brack-ets were bonded to the upper and lower arches.Alignment and leveling was achieved using 0.012-inchnickel-titanium arch wires to 0.020-inch stainless steelarch wires in the lower arch and up to a full size0.022 X 0.028-inch stainless steel arch wire on the upperarch. At this point, one mini-implant (Neodent,Curitiba, PR, Brazil) of 1.6-mm diameter and 9.0-mmlength was inserted buccally between the first andsecond premolars on each side of the mandible. Themini-implants were connected to canines using stainlesssteel 0.012-inch ligatures to establish an indirect

Ciinicai Section

Figure 6 Post-treatment panoramic and cephalometric radiographs

anchorage for distal movement of the molars. Thebrackets of the second premolars were removed and twonickel-titanium open coil springs inserted on each side(Figure 4). After the second molar had been moved 2-mm distally, a new arch wire was fabricated with anomega-loop close to the tube, to avoid any relapse.Then, the first molar was also moved distally; subse-quently, the second premolar again received a bracketand was moved. At this point, the mini-implants wereremoved, and the first premolar and canines were moveddistally with elastic chains connected directly to theposterior teeth. Lower incisors were retracted witha 0.018 X 0.025-inch arch wire with bull loops. Onthe upper arch, the rectangular arch wire of0.022 X 0.028 inches was expanded and made withaccentuated buccal torque of the roots to correct theposterior crossbite. The total time of treatment was28 months.

At the end of the treatment, an acceptable facialappearance associated with a class I molar and canine

relationship was achieved, as well as excellent intercuspa-tion, with an ideal overjet and overbite. Further, theposterior crossbite was corrected with upper-arch expan-sion and lower arch contraction and distal movement(Figure 5). Panoramic and cephalometric radiographydemonstrated good parallelism among the roots withoutany significant résorption (Figure 6). Cephalometricsuperimposition showed that the lower first molar hadbeen uprighted and moved distally, the lower incisorsretroclined and the mandible rotated slightly in acounterclockwise direction (Figure 7 and Table 1). Twoyears after treatment, stability of these treatment out-comes had occurred (Figure 8).

Discussion

The development of skeletal anchorage represents theemergence of a new paradigm in orthodontics.'" Certainskeletal maloeelusions, which in the past were onlytreatable with orthognatic surgery, can now be treated

Clinical Section Class III malocclusion treated with mini-implants 261

with orthodontics alone.^"'''''^ Several skeletal discre-pancies are still best treated with orthognatic surgery,which serves as the best option to solve either esthetic orfunctional problems.'*'^ However, moderate skeletal

Table 1 Cephalometric measurements.

Figure 7 Cephalometric superimposition. Anterior cranial base registered on the inner countour of sella and mandible registered on theinner cortical structure of the symphysis

problems, such as the case described in this manuscript,can now be successfully treated with anchorage facili-tated by mini-implants and/or mini-plates.

Potential treatment options for the compensation orcamouflage of the maloeclusion described here includethe use of elastics, a protraction facemask, cervicalheadgear on the lower arch, or even a lingual archto improve anchorage and develop class IIImechanics.•'•^''^•'^ The use of class III elastics, even withrectangular arch wires, causes the extrusion of uppermolars, provoking clockwise rotation of the mandible,increasing the LAFH and opening the anterior bite.'^Consequently, as this patient already had an accentu-ated LAFH, this option was contraindicated. Extra-oralanchorage with a protraction facemask or headgear wasdismissed as possibilities; those devices are usuallyrefused by adult patients and require strict complianceto be successful. Mini-plates are obviously the bestanchorage unit for orthodontic mechanics and allow themovement of a large number of teeth and sometimes,even the whole arch may be moved at once withmini-plates.''''"''^ Nevertheless, the installation andremoval of mini-plates both entail invasive surgicalprocedures, which sometimes discourage the patient andleads to them opting instead for mini-implants.^'""'^ In

Measurements

SNASNBANB

Facial convexity (NA.APog)Facial angle (PoOr.NPog)Y-axisSN.GoGn1-NA D1-NA (mm)1-NB (°)

1-NB (mm)Inter-incisal angleUl-S lineLl-S lineIMPAFMAFMIA

Norms (SD)

82"(3)80° (3)2° (2)

0°(2)87° (3)59' (6)32° (3)22"5 mm

25°5 mm131° (5)0 mm (2)0 mm (2)90° (4)25° (3)65° (4)

Initial

82°84.5°-2.5°

- l r92°

56°20°32°8 mm24°4.5 mm128°—2 mm096°16°68°

Final

83"86°

-3°-11°93°55°19°34°9 mm20°2 mm132°- 1 mm1 mm90°15°75°

262 Farret et al JO September 2013

Figure 8 Intra-oral photographs two years post-treatment

the case presented here, we needed a mediimi rate ofdistal movement and, therefore, we offered the choice ofone mini-implant or mini-plate in each side of themandible. The patient chose the less invasive option,despite knowing that this course of treatment wouldtake more time.

The treatment achieved an ideal overjet and overbite,which remained evident at 2-year follow up aftertreatment. The establishment of good intercuspation,overjet and overbite are especially important formaintaining the stability of the occlusion, mainly incases of class III malocclusion. The total superimposi-tion yielded a small improvement on the facial profile,because of the sHght mandibular counterclockwise shift.Further improvement may be conditional dependingupon the elimination of the edge-to-edge contact on theright side and the crossbite on the left side. Furthermore,the distal movement and uprighting of the lower molarswas achieved without extrusion. Superimposition alsorevealed mesial migration of the upper first molar, whichwas caused by expansion on the upper arch, andfacilitated easier correction of the class III relationship.

Conclusion

The use of a single mini-implant in each side of themandible to move the lower teeth distally proved to beefficient in the treatment of moderate skeletal class IIImalocclusion.

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