Mandibular tripod advancement of a Class II Division 2 ... · CASE REPORT Mandibular ‘‘tripod’’ advancement of a Class II Division 2 deepbite malocclusion LauraE.Low,a TheodoreE.Moore,b

CASE REPORT

Mandibular ‘‘tripod’’ advancement of a Class IIDivision 2 deepbite malocclusion

Laura E. Low,a Theodore E. Moore,b Kevin R. Austin,c Richard G. Burton,d Steve D. Marshall,e Karin A. Southard,f

and Thomas E. Southardg

Iowa City, Iowa, Lone Tree, Colo, and Nixa, Mo

This case report describes the treatment of a 25-year-old woman with a Class II malocclusion, secondary tomandibular skeletal deficiency, and mild overclosure. Inferior surgical repositioning of the maxilla is often thetreatment of choice for patients with maxillary vertical deficiency; however, this patient had borderline verticaldeficiency that was treated with a mandibular ‘‘tripod’’ advancement (leveling of the mandibular arch after sur-gery) coupled with a setback and down-grafting genioplasty. The surgical-orthodontic treatment plan, com-bined with cosmetic dentistry, resulted in dramatically improved facial esthetics and occlusal relationships.(Am J Orthod Dentofacial Orthop 2010;137:285-92)

Optimal treatment for an adult with mandibularanteroposterior deficiency and maxillary verti-cal deficiency (short lower anterior face height)

can include mandibular advancement and maxillarydown-graft osteotomies. However, for those with man-dibular anteroposterior deficiency, borderline verticaldeficiency, and normal incisal display, a decision mightbe made to advance the mandible only and forego themaxillary down-graft osteotomy. In this latter case, itcan still be advantageous to maximize an increase inthe lower anterior face height as the mandible isadvanced surgically.

How can this be done? Jacobs and Sinclair1 sug-gested that, for vertically overclosed deepbite patients,leveling of the mandibular occlusal plane might bebest after surgery. In this way, the mandibular incisors(not intruded preoperatively) are carried down the lin-gual surfaces of the maxillary incisors more duringthe surgical advancement than if they had been intrudedpreoperatively. Because the curve of Spee is not leveled

aResident, Department of Orthodontics, University of Iowa, Iowa City.bPrivate practice, Lone Tree, Colo.cPrivate practice, Nixa, Mo.dProfessor, Department of Oral and Maxillofacial Surgery, University of Iowa,

Iowa City.eVisiting associate professor, Department of Orthodontics, University of Iowa,

Iowa City.fProfessor, Department of Orthodontics, University of Iowa, Iowa City.gProfessor and head, Department of Orthodontics, University of Iowa, Iowa

City.

The authors report no commercial, proprietary, or financial interest in the

products or companies described in this article.

Reprint requests to: Thomas E. Southard, Department of Orthodontics, College

of Dentistry, University of Iowa, Iowa City, IA 52242; e-mail, tom-southard@

uiowa.edu.

Submitted, June 2007; revised and accepted, October 2007.

0889-5406/$36.00

Copyright � 2010 by the American Association of Orthodontists.

doi:10.1016/j.ajodo.2007.10.063

preoperatively, at surgery, the advanced dentition con-tacts at only the anterior and most posterior tooth oneach side. Hence, the common name for the procedureis ‘‘tripod’’ advancement. Postoperatively, the posteriorteeth can be brought into occlusion by extrusion. We areunaware of any case report that demonstrates this con-cept. The purpose of this report is to present such a case.

DIAGNOSIS AND ETIOLOGY

A 25-year-old white woman came to the orthodonticclinic at the University of Iowa in Iowa City, concernedabout her smile (Figs 1-5). Her medical history showedno contraindications to treatment. She had sufferedtrauma to her maxilla and incisors and had previouslyundergone orthodontic therapy. Her third molars hadbeen extracted.

Clinical and radiographic examinations showed anAngle Class II Division 2 malocclusion, a convex profilewith mandibular skeletal retrusion (ANB angle, 6�),short vertical proportions (short lower anterior faceheight), low mandibular plane angle, adequate softtissues and bony pogonion, everted lower lip, deeplabiomental sulcus, obtuse lip-chin-throat angle, andmaxillary dental retrusion. Severe attrition of the maxil-lary and mandibular anterior teeth was noted. The max-illary anterior teeth had supraerupted, leading toexcessive gingival display when smiling. Her overbitewas 100%, and overjet was 1 mm. The maxillary dentalmidline was 1 mm to the right, the maxillary tooth size-arch length discrepancy was –3 mm, the curve of Speewas moderate, and there was no evidence of a shiftfrom centric relation to centric occlusion. Examinationof the temporomandibular joint showed an asymptom-atic, anterior-displaced disc with reduction (popping)on the left side and deviation to the right on opening.

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mailto:[email protected]

Fig 1. Pretreatment facial photographs.

Fig 2. Pretreatment intraoral photographs.

286 Low et al American Journal of Orthodontics and Dentofacial Orthopedics

February 2010

TREATMENT OBJECTIVES

Our goals were to improve the patient’s facial es-thetics and provide a harmonious occlusion. Facialtreatment objectives included decreasing overall fa-cial convexity, softening the chin projection, decreas-ing the labiomental sulcus depth, and increasing thelower anterior face height. Dental treatment objec-tives were to correct her Class II molar and canine re-lationships, correct her deepbite, reduce her excessivegingival display, and level, align, and coordinate herdental arches.

TREATMENT ALTERNATIVES

In a recent study at the University of Iowa, patientswho initially had an ANB angle equal to or greater than6� were consistently judged by laypersons to haveprofile improvement after mandibular advancementsurgery.2 In contrast, profiles of patients who initiallyhad an ANB angle less than 6� were sometimes judgedto be improved and sometimes not improved after sur-gery. From this study, the profile of our patient was pre-dicted to be improved after mandibular advancementosteotomy.

Fig 3. Pretreatment study models.

Fig 4. Pretreatment radiographs.

Fig 5. Pretreatment cephalometric tracing.

American Journal of Orthodontics and Dentofacial Orthopedics Low et al 287Volume 137, Number 2

Although a nonsurgical option of masking the un-derlying apical base discrepancy (headgear or extrac-tion of first maxillary premolars) was presented to thepatient as an alternative, the resulting esthetic outcome

Fig 6. Presurgical facial photographs.

Fig 7. Presurgical intraoral photographs.


February 2010

was not recommended. Instead, she chose an orthodon-tic-surgical solution. Additionally, because of her bor-derline short lower anterior face height, a decisionwas made to address the vertical dimension.

The final nonextraction treatment plan consisted ofcomposite restoration of the mandibular incisors to fa-cilitate bonding, placement of fixed orthodontic appli-ances, and alignment of the arches. The curve of Speewould not be leveled to prevent intruding the mandibu-lar incisors. Surgery would consist of a mandibular ‘‘tri-pod’’ advancement to maximize lower anterior faceheight and a genioplasty setback to reduce her chin pro-

jection. Hoffman and Moloney3 suggested that posteriorpositioning of the chin is a reliable procedure to softenthe chin projection after mandibular advancement,particularly in a patient with a Class II Division 2malocclusion.

Additionally, we considered the anterior mandibularheight and its contribution to our patient’s vertically de-ficient face. This dimension of the mandible is oftenoverlooked.4 The sliding setback genioplasty has the ad-vantage of softening pogonion and slightly increasingthe vertical dimension of the lower face. An alternativeoption would have been genioplasty with an anteriorly

Fig 8. Presurgical casts mounted on an articulator for‘‘tripod’’ advancement.


tapered osteotomy, but this type of genioplasty, whiledecreasing chin projection, does not alter the anteriorvertical height of the mandible. After surgery, the man-dibular occlusal plane would be leveled by extrusion ofthe premolars and the first molars with vertical elastics,alleviating the need to overcome the heavy bite forcestypical of a deepbite patient.5

TREATMENT PROGRESS

The maxillary dentition was banded and bondedwith edgewise appliances (0.022 3 0.028-in slot). Themandibular central incisors were restored, and the man-dibular arch was banded and bonded. The arches werealigned and coordinated. Iowa spaces, 2 to 3 mm ofspace distal to the lateral incisors, were placed in themaxillary arch to facilitate full mandibular canine ad-vancement into a Class I relationship without interfer-ence from the incisors (Figs 6 and 7). The curve ofSpee was not leveled, and casts were mounted on an ar-ticulator (‘‘tripod’’ advancement) to confirm the surgicalmovements presurgically (Fig 8). Surgery was per-formed a year after treatment started. In addition tomandibular advancement, the surgery included setbackand down-grafting genioplasty. After surgery, the pa-tient used guiding elastics for a week. Leveling of themandibular arch was started with bilateral triangle elas-tics at the canines and posterior box elastics. Finalorthodontic detailing proceeded, and the patient wasdebanded 10 months after surgery.

Eight days after debanding, the patient was in an au-tomobile accident. All 4 maxillary incisors were sublux-ated lingually and were mobile when she came to the

orthodontic clinic. She was instructed to wear her tem-porary retainers full time in an attempt to correctly po-sition them. Later, she underwent a rhinoplasty tocorrect a nasal deformity resulting from the accidentalong with root canal therapy and composite buildupsof her maxillary incisors. Maxillary and mandibularHawley retainers were placed with instructions for ini-tial full-time wear and then long-term nighttime wear.

TREATMENT RESULTS

Facial esthetics were dramatically improved at theend of treatment (Figs 9-13). The apical base discrep-ancy was reduced as the mandible was advanced, andthe ANB angle decreased from 6� to 1�. Lower anteriorface height was increased after the mandibular incisorswere advanced downward and forward along the lingualsurfaces of the maxillary incisors. The labiomental sul-cus was reduced, and the projection of the soft-tissuepogonion was softened. The patient’s final smile es-thetics were enhanced through reduction in gingival dis-play and attainment of a balanced smile arc. Compositebuildups enhanced her smile esthetics and were an inte-gral part of the treatment plan.

A well-interdigitated Class I molar and canine rela-tionship was achieved, and the final overbite and overjetwere minimal (Figs 10 and 11). The mandibular midlinewas approximately 1 mm to the left of the face. Canineguidance was established bilaterally during lateralexcursive movements. The posttreatment panoramicradiograph showed blunting of the maxillary centralincisor roots with minimal change in root length.

As demonstrated by superimposition of the initialand final lateral cephalometric tracings (Fig 14), themandible was advanced significantly downward andforward. The maxillary incisors were proclined, withminimal movement of the mandibular molars andincisors.

DISCUSSION

There is a general lack of information on the ‘‘tri-pod’’ advancement in the literature. Yet, this treatmentcan be valuable for patients with borderline lower ante-rior face height deficiency. By leveling the mandibulararch after surgery, additional lengthening of the loweranterior face can be achieved.

Was this the appropriate procedure for this patient?Would a maxillary down-graft, in conjunction withmandibular advancement, have resulted in a more favor-able result? In this patient, if the maxilla had been ver-tically deficient, it would have been a mild deficiency.Furthermore, the initial resting lip to incisor distancewas 7 mm. Ideal incisor display is 2 to 4 mm, but the

Fig 10. Posttreatment intraoral photographs.

Fig 9. Posttreatment facial photographs after the incisor buildups.


February 2010

maxillary incisors were supraerupted after incisal-edgeattrition.6 Also, the upper lip length was 17 mm, whichis at the short end of normal for women, and the patienthad a high smile line and excessive incisor and gingivaldisplay, at least in part due to hyperactivity of her smilemusculature. In such a patient, maxillary incisor posi-tion should be judged after the maxillary arch is leveledand the maxillary incisors are provisionally restored.

After preoperative orthodontic treatment, the restingmaxillary incisor position was approximately 2 mm (al-lowing for several millimeters of buildup material).

This, coupled with hyperactivity of the smile muscula-ture, led us to increase the patient’s lower anterior facialheight with the ‘‘tripod’’ advancement and avoida down-graft of the maxilla that would have been unes-thetic and would have increased her gummy smile.

How much did the ‘‘tripod’’ advancement help thevertical dimension? The amount of additional verticaldimension gained should equal the amount that themandibular incisors were not intruded preoperatively.In a recent systematic review and meta-analysis, theamount of true mandibular incisor intrusion during

Fig 11. Postreatment study models.

Fig 12. Posttreatment radiographs.

Fig 13. Posttreatment cephalometric tracing.


orthodontic treatment ranged widely from –0.19 to 2.84mm depending on the appliances used.7 Even a few mil-limeters of additional facial height, which one canassume was gained here, can improve esthetics in

Fig 14. Pretreatment and posttreatment superimposed cephalometric tracings.


February 2010

a patient who is vertically deficient. Additionally, level-ing of the curve of Spee by using conventional mechan-ics has been shown to be relatively stable.8,9

How much did the genioplasty procedure aid in theesthetic outcome? Wessberg et al10 noted that, ina short-face patient, the deformity is often located inthe anterior mandible. By bringing the chin down 5mm, in addition to setting it back, the labiomental sulcuswas reduced, and facial height was increased. The totalincrease in facial height with mandibular ‘‘tripod’’ ad-vancement and genioplasty down-graft was approxi-mately 13 mm. Overall, the vertical change wassubstantial.

CONCLUSIONS

Treatment of a patient with a Class II malocclusionand vertical overclosure was presented. Nonextractioncorrection of the malocclusion was achieved with ortho-dontic treatment, surgical advancement of the mandible,a setback and down-grafting genioplasty, and cosmeticdentistry. By postponing leveling of the mandibulararch until after surgery (‘‘tripod’’ advancement), addi-tional facial height was achieved.

REFERENCES

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orthognathic surgery cases. Am J Orthod 1983;84:399-407.

2. Shelly A, Southard T, Southard K, Casko J, Jakobsen J,

Fridrich K, et al. Evaluation of profile esthetic change with man-

dibular advancement surgery. Am J Orthod Dentofacial Orthop

2000;117:630-7.

3. Hoffman G, Moloney F. The stability of facial osteotomies. Part 6.

Chin setback. Aust Dent J 1996;41:178-83.

4. Fridrich K, Casko J. Genioplasty strategies for anterior facial ver-

tical dysplasias. Int J Adult Orthod Orthognath Surg 1997;12:

35-41.

5. Pepicelli A, Woods M, Briggs C. The mandibular muscles and

their importance in orthodontics: a contemporary review. Am J

Orthod Dentofacial Orthop 2005;128:774-8.

6. Burstone C. Lip posture and its significance in treatment planning.

Am J Orthod 1967;53:262-84.

7. Ng J, Major P, Heo G, Flores-Mir C. True incisor intrusion attained

during orthodontic treatment: a systematic review and meta-anal-

ysis. Am J Orthod Dentofacial Orthop 2005;128:212-9.

8. Shannon K, Nanda R. Changes in the curve of Spee with treatment

and at 2 years posttreatment. Am J Orthod Dentofacial Orthop

2004;125:589-96.

9. De Praeter J, Dermaut L, Martens G, Kuijpers-Jagtman AM.

Long-term stability of the leveling of the curve of Spee. Am J

Orthod Dentofacial Orthop 2000;121:266-72.

10. Wessberg G, Fish L, Epker B. The short face patient: surgical-

orthodontic treatment options. J Clin Orthod 1982;16:668-85.

Mandibular tripod advancement of a Class II Division 2 ... · CASE REPORT Mandibular ‘‘tripod’’ advancement of a Class II Division 2 deepbite malocclusion LauraE.Low,a TheodoreE.Moore,b

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