Temporomandibular disorder is acollective term embracing a numberof clinical problems that involve themasticatory musculature, the tem-poromandibular joint (TMJ), associ-ated structures, or both that havemany common symptoms. The termis synonymous with others frequentlyutilized such as myofascial pain anddysfunction syndrome, temporo-mandibular joint syndrome and

craniomandibular disorders. Tempor-omandibular disorders are currentlyrecognized as a major cause of non-dental pain in the orofacial region andare considered a subclassification ofmusculoskeletal disorders.1

Classic signs and symptoms associ-ated with TMD are pain in the preauricular region and contiguousareas to include, TM joint and

masticatory and cervical muscles:limitation or deviation in mandibularmovements; and TM joint sounds(clicking, popping, crepitus). Thepain is usually aggravated by chewingor other jaw function. Commonlyassociated co-existing/co-morbidityfactors with TMD are headache, neckache, facial pain, ear and jaw ache.

by S. Jay Bowman, DMD, MSD

Various treatment mechanics havebeen created to direct the eruption ofimpacted teeth, including the appli-cation of intra- and interarch forcesto some type of attachment on theaffected teeth. The present commu-nication describes the use of two sim-ple auxiliaries, the Monkey Hook*and the Kilroy Spring,* for the direct-ed eruption of impacted and/or thecorrection of severely rotated teeth.

The Monkey Hook auxiliaryThe Monkey Hook1 is simply a

short section of wire with open loopson opposite ends (Fig. 1). Forces todirect the eruption or rotation of teethare applied from the Monkey Hookwith intraoral elastics, elastic chains,elastic thread, or super-elastic coil

springs. Closing the loops with plierspermits the secure connection of theMonkey Hook to a bondable “loopbutton” or the linking of one hook toanother to form a “chain” (Fig. 2).

Exposure and attachmentsfor impacted teeth

The advent of direct bonding hasallowed for smaller exposure sitesfor impacted teeth with less associ-ated morbidity when placing attach-ments. For instance, a loop button orbondable eyelet, consisting of a1 mm helix of round wire that iswelded or braised to a small diame-ter bondable base (Fig. 1), may beeasily direct-bonded to nearly anyexposed enamel surface of animpacted tooth.

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Managing impactedcanines with MonkeyHook and Kilroy Spring

Temporomandibular disorders:epidemiologic and etiologicconsiderations (part 1)

Figure 1. A and B. The Monkey Hook isan “S-shaped” section of wire that islinked to a bondable “loop button.” Thisauxiliary is direct-bonded to an impact-ed or rotated tooth to permit the addi-tion of directional forces via intermaxil-lary elastics, super-elastic coils spring,elastic chain or thread. C. The conceptwas influenced by the children’s game,“Barrel Full of Monkeys.”

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by Drs. Ulises A. Guzman & Henry A. Gremillion

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1a.

1b.

Growing pains

Growth in an orthodontic officeneeds to be monitored carefullydepending upon its age. Whetheryours has just opened its doors, oryou’re ready to close down, readhow if you give your practice its duediligence, it will grow, thrive andfinish in a very satisfying condition.

Practice, page 12

Schools launchTMJ study

A team of researchers from NewYork University College of Dentistry(NYUCD) and the NYU School ofMedicine (SOM) partner with theUniversity of Medicine and Dentistryof New Jersey (UMDNJ) on a majorNIH grant to fund the most compre-hensive study to date on the under-lying causes of temporomandibulardisorder.

Student Corner, page 15

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A vital key to effectively market yourpractice is to get exposure to inter-ested consumers during their deci-sion-making or buying cycle. In thepast, that meant being in the YellowPages; today, it means not only hav-ing a credible, information-rich Website, but being found on the top ofsearch engine results. Learn the top10 ways to build a winning Web site.

Industry Report, page 16

1c.

Applying an additional amount ofbonding adhesive (e.g., Fuji GI LC),acting as a fillet, around (and evenover the edge of the bondable base)appears to improve the retention ofthis attachment.

A Monkey Hook is connected tothe loop button attachment prior todirect bonding this combination tothe exposed tooth. The vertical loopis positioned parallel to the roots ofthe teeth adjacent to the impactedone. In this orientation, a continuousarch wire may be placed through thelumen of this loop button later intreatment when the directed erup-tion of the tooth is sufficient. If thetooth is deeply impacted, a secondMonkey Hook can be easily linked tothe first one. Then, a stainless-steelligature is used to tie the free end ofthe Monkey Hook to the bracket on atooth adjacent to the exposure site.This will stabilize the hook untilforces are later applied. As a result, aportion of the Monkey Hook mayextend through gingival tissues afterthe exposure and is available for theapplication of a variety of forcemechanics (Fig. 3).

Force applicationsFor palatally-impacted canines, it

is important to direct the eruption ofthe affected tooth away from theroots of any adjacent teeth to reducethe risks of root resorption. In someinstances, the tooth must be movedtowards the lingual or distal beforelateral movements are attempted. Inaddition, these teeth should first beerupted occlusally prior to anyattempt to direct the tooth laterallytowards the dental arch form. Asthere is obviously no periodontalligament surrounding the enamelcrown of a tooth, it is nearly impos-sible to move the crown throughbone. Consequently, erupting thetooth vertically to clear the crownfrom the supporting bone will facili-tate later lateral movements.

Monkey Hook forces

Vertical eruptionCommon intra-arch mechanics

that have been previously used todirect the eruption of impacted teeth(e.g., elastic thread applied to a goldchain) may tend to adversely tip orintrude the adjacent teeth. As analternative, vertical eruptive forcescan be created using intermaxillaryelastics, stretched from the MonkeyHook to the opposing dental arch(Fig. 3). Although there is no effecton teeth adjacent to the exposure,this arrangement introduces theunpredictable factor of patient com-pliance with elastic wear.

Sling Shot EffectAn alternative method is to pro-

duce intra-arch force using multipleMonkey Hooks connected to the sameloop button attachment; much likekeys on a key ring (Fig. 3). Elasticchains are then connected from eachMonkey Hook to teeth adjacent to theexposure; thereby, creating a “slingshot” effect (Fig. 3). A closed coilspring is placed on the base arch wireto prevent tipping of the adjacentteeth towards the impacted tooth. Acombination of intermaxillary elasticsand the “sling shot” may be used toprovide simultaneous vertical and lat-eral eruptive forces (Fig. 3).

The Kilroy Spring auxilliaryThe Kilroy Spring2,3 is a pre-

formed module that is slid onto arectangular continuous arch wire inthe location of an impacted tooth(Fig. 4). The vertical loop of the Kil-roy Spring extends perpendicularlyto the occlusal plane in its passivestate (Fig. 5). A stainless steel liga-ture is then threaded through thehelix at the apex of this verticalloop. Then the vertical loop isdirected toward the impacted tooth.The ligature is tied either directly tothe loop button or to a Monkey Hooklinked to that attachment. As anoth-er alternative, either the MonkeyHook or Kilroy Spring may be tied tothe links of a typical “gold chain”that has been attached to theimpacted tooth.

Kilroy Spring forcesThe Kilroy Spring is supported

by: 1) the rectangular base archwire, 2) reciprocal anchoragederived from the incisal one-third ofthe adjacent teeth (where the later-al extensions or “arms” of the KilroySpring contact those teeth on thebuccal surface) (Fig. 5). It is criticalthat a rectangular base wire is usedto prevent adverse lingual crowntorque of those adjacent teeth. TheKilroy Spring may need to be peri-odically re-tied or adjusted to main-tain a constant force as the tootherupts.

Managing impactedcanines with Monkey ...

ORTHO TRIBUNE | FEBRUARY 2008 Trends 7

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Figure 2. A and B. Monkey Hooks canbe linked together to form a chain.

Figure 3. A. Monkey Hooks can be applied to a bonded loop button on a buccallyor palatally-impacted tooth. B. Elastic chain, stretched from the Monkey Hooks tobrackets on the teeth adjacent to an impacted tooth, produce lateral and/or verticaldirectional forces (i.e., “sling shot” effect). C. Intermaxillary elastics, supported by theopposite dental arch, can be attached to a third Monkey hook to produce verticaleruptive forces.

Figure 4. A. Kilroy Springs, auxiliaries that are slid onto a rectangular continuousarch wire, were designed to produce both vertical and lateral eruptive forces forimpacted teeth. The design of the Kilroy I Spring (for palatal canines) reminded thedesigner of the iconic “Kilroy Was Here” graffiti of the 1940s. B and C. Kilroy IISpring was designed for use with labially-impacted canines. The cantilever natureof the auxiliary requires careful adjustment to balance forces to prevent tissueimpingement.

Figure 5. A. When passive, the verticalloop of the Kilroy Spring is positionedperpendicular to the plane of occlusion.B. To activate the Kilroy Spring, a stain-less steel ligature is passed through thehelix, at the end of the vertical loop, andtied to the bonded loop button on theimpacted tooth. C. The vertical loop hasbeen directed to the impacted tooth andsecured in place. D. Vertical and lateraleruptive forces are directed to theimpacted tooth by the Kilroy Spring. E.Support is derived from 1) the continu-ous rectangular arch wire and 2) theincisal 1/3rd of the adjacent teeth as con-tacted by the extensions of the auxiliary.

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The Kilroy Spring was designed toproduce primarily vertical and someconcurrent lateral eruptive forces forpalatally-impacted canines (Figs. 4, 6,7, 8). The Kilroy II Spring producesvertical forces and was intended forbuccally-impacted teeth (Fig. 4).

Due to the multiple helices and

cantilever design of the Kilroy II,there is a chance of tissue impinge-ment adjacent to the impacted tooth;therefore, more frequent visits tomonitor progress are recommended.

The amount of force produced byeither Kilroy Spring is increased ordecreased by bending the verticalloop towards or away from theimpacted tooth prior to its installa-tion (Fig. 9).

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Figure 6. A. Thirteen-year-oldfemale with palatally-impacted

right canine. After surgicalexposure and placement of a

bonded loop button, a Kilroy Springauxiliary was ligated to the affectedcanine as part of typical continuousarch mechanics. B and C. After two

months, the tooth has been mildlyhyper-erupted. D. Super-elastic wire

is inserted through the loop buttonattachment to direct the tooth

labially. E. A .018” stainless-steelarch wire was used to “step” the

canine into position. F. Fivemonths after surgical exposure, a

bracket is bonded to the canineand a Compliance+ spring*

auxiliary is slid onto the round archwire and secured in the vertical slot

of the Butterfly System bracket*5,6

and an intermaxillary elastic wasused to activate the spring to

produce labial root torque.G. Immediately upon removal ofthe fixed appliances, a positioner

was worn 24 hours/day for oneweek to finalize the occlusion

and improve the gingival health7,8

H. Final result achievedin 21 months.

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Figure 7. A 1 and 2. Twelve-year-old female with palatally-impacted right canine.B. 1 and 2. Kilroy Spring auxiliary was slid onto a rectangular arch wire and thevertical loop was ligated to the bonded attachment on the canine. Reciprocal forces todirect the eruption of the impacted tooth were derived from the adjacent teeth and thearch wire. C. Vertical and lateral displacement after four months. D. A second bond-ed attachment is placed on the buccal surface and two Monkey Hooks with elasticschains are connected to the attachments to produce a rotational couple. E. After onemonth of rotation. F. After 4 months of rotation, a bracket is bonded to the tooth. G.Final results. Note: Kilroy Spring was in place for 8 months and rotation with theMonkey Hooks required 4 months.

Fig. 7A1

& 2

Fig. 6 e, f, g and h

Fig. 6 a, b, c and d

Fig. 7B1& 2

Fig. 7G1& 2

7c.

7e. 7f.

7d.

Due to the flexibility of the KilroySpring, it can be adjusted to fit the avail-able arch length, even if the space forthe impacted tooth is wider or narrow-er than the impacted tooth. In addition,the vertical loop of the Kilroy Springcan be adjusted to produce some mildforce to assist in closing, maintaining,or opening of that space (Fig. 9).

Rotational couples, retractionwith the Monkey Hook

Impacted teeth are also fre-quently rotated and may requiredirectional forces to turn them intoappropriate alignment. A secondloop button may be bonded to the

crown of the affected tooth on theside opposite that of the originalattachment. Monkey Hook andelastic chain combinations are con-nected from each loop button inopposite directions to produce arotational couple (e.g., forcesdirected to the lingual cleat of amolar and also directed to the ante-rior teeth) (Figs. 7, 8).

These Monkey Hook and elasticchain or Niti coil spring combina-tions can also be used for slidingspace closure or for retracting indi-vidual teeth and can be connected tothe heads of mini-screw anchors aswell (Fig. 10).4 In these situations,

the Monkey Hook is attached to asoldered, crimpable, or vertical slothook.5,6 As a “low friction” alterna-tive, a right angle bend is made atone end of the Monkey hook and

then it is “hooked over” the archwire in the appropriate location toproduce retraction (Fig. 10).

ORTHO TRIBUNE | FEBRUARY 2008 Trends 9

Figure 8. A, B and C. Sixteen-year-oldfemale with palatally-impacted caninesthat were surgically-exposed and loopbuttons were direct-bonded. KilroySprings were placed onto a rectangulararch wire and the vertical loops were tiedto the bonded attachments with stainlessligatures to direct vertical eruption for 6months. D, E and F. The lingual surfaceof the crowns were facing labially andrequired a rotational couple from twoMonkey Hooks and elastic chain to rotatethem into correct position along with sub-stantial labial root torque and intermax-illary elastics. G. Treatment completed in34 months.

Figure 9. A. The force produced by the Kilroy Spring can be adjusted by simplybending the vertical loop away from the impacted tooth (more force) or towardsthe tooth (less force) B. The Kilroy Spring can be expanded or constricted to fit theavailable arch length where the impacted tooth is missing or to produce some mildforces for opening or closing that space.

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1. Surgical exposure.2. Direct bonding a loop button

attachment linked with MonkeyHook.

3. Add a fillet of additional adhe-sive around, or even over, thebonding base of the attachmentto improve retention.

4. Tie a steel ligature from theMonkey Hook to a bracket or thearch wire to stabilize it untilforces are applied.

5. Vertical eruptive forces — inter-maxillary elastics from the Mon-key Hook to the opposing arch.

6. Distal directed forces prn —Monkey Hook with elastic chainconnected to a cleat or buttonattachment on the lingual of thefirst molar.

7. Vertical eruptive forces — Kilroy

Spring tied to the Monkey Hookor loop button.

8. Sling Shot forces — Two MonkeyHooks with elastic chain, linkedto the loop button, directing thetooth towards the base arch wire.Coil springs on the continuousarch wire are used to open orhold space for the impacted tooth.

9. Rotational couple — loop buttonsplaced on opposite sides of thetooth with Monkey hooks andelastic oriented in oppositedirections to “spin” the tooth.

10. Base arch wire or superelastic“overlay” auxilliary wire thread-ed through the loop buttonto center the tooth within thealveolus.

11. Bonding an orthodontic bracketto detail the correction.

Possible steps for directing theeruption of an impacted tooth:

9a.

8f.

8e.

8d.

8c.8b.

8a.

8g.

9b.

SummaryInitiating treatment with a bond-

able loop button (with a linked Mon-key hook), attached during the rou-tine surgical exposure of animpacted tooth, provides for a num-ber of mechanical options: 1) inter-maxillary elastics may be employedfrom the open loop of the MonkeyHook to generate vertical eruptiveforces, 2) a pre-formed KilroySpring auxiliary may be tied to theMonkey Hook or directly to the loopbutton for vertical and lateral erup-tive forces without dependenceupon compliance, 3) two MonkeyHooks (linked to elastic chain) maybe added to produce lateral or verti-cal “sling shot” eruptive forces.

After sufficient eruption of thecrown of the tooth, any rotations maybe resolved by introducing a rotation-al couple using two Monkey Hooks.Elastic chains are connected to thesehooks; directing forces in opposingdirections from loop buttons that areapplied on opposite sides of the tooth.In addition, the base arch wire or amore flexible, auxiliary “overlay”wire may be threaded through theloop on one end of the Monkey Hookor through the lumen of the loop but-

ton to complete the directed eruptionprior to the placement of a typicalbracket on the tooth. The combina-tion of the Monkey Hook, the loopbutton, and the Kilroy Spring offersimple and predictable solutions forthe resolution of impacted andseverely rotated teeth.9,10,11

*American Orthodontics, Inc.,1714 Cambridge Ave.,

Sheboygan, WI 53082-1048.

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Managingimpactedcanines ...

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References1. Bowman, S.J. and Carano, A.: The

Monkey Hook: An auxiliary forimpacted, rotated, and displacedteeth, J. Clin. Orthod. 36:375-378,2002.

2. Bowman, S.J. and Carano, A.: KilroySpring for impacted teeth, J. Clin.Orthod. 37:683-688, 2003.

3. Corrado, G.: Un nuovo dispositivo atrazione verticale per canini mas-cellari in inclusione palatale: “Kil-roy Spring I”. Master’s Thesis, Uni-versità Degli Studi di Siena FacoltàMedicina e Chirugia, Siena, Italy,2005.

4. Bowman, S.J.: Thinking outside thebox with mini-screws, In: Microim-plants as Temporary OrthodonticAnchorage, ed. McNamara, Jr. andRibbens, Craniofacial GrowthSeries, Ann Arbor, Vol. 45, 2008

5. Bowman, S.J. and Carano, A.:Improvements in pre-adjustedappliances: Butterfly brackets,Good Prac. 2:5-7, 2001.

6. Bowman, S.J., and Carano, A.: TheButterly System, J. Clin. Orthod.38:274-287, 2004.

7. Bowman, S.J. and Carano, A.: Short-term, intensive use of the toothpositioner in case finishing, J. Clin.Orthod. 36:216-219, 2002.

8. Bowman, S.J.: Fine-tuning case com-pletion with the new Pro-flex posi-tioner, AOAppliances, etc. 7:1-2,2003.

9. Bowman, S.J.: Canine obediencetraining, University Dental Hospi-tal, University of Sydney, Sydney,Australia, June 25, 2003.

10. Bowman, S.J. and Carano, A.:Canine obedience training: Mon-key Hooks and Kilroy Springs, J.Indian Orthod. Soc, 36:179-184,2004.

11. Bowman, S.J.: Trouble-shooting tril-ogy: simple solution to everydayclinical problems, 104th AnnualSession of the American Associa-tion of Orthodontists, San Francis-co, 2005.

T4CII made by Myofunctional Research Co.by Dr. Denis Cunneen

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About the authorOT

Figure 10. A and B. Combination ofMonkey Hook and super-elastic coilspring used to retract individual teeth ordental segments. One end of the Monkeyhook is bent 90 degrees and is hookedover the arch wire. C. Monkey Hookscan also be used to connect from theheads of mini-screws (TADs) to elasticchain or super-elastic coil springs.11

Dr. Bowman is in the private practice oforthodontics. He is an Adjunct Associate

Professor at Saint Louis University andthe Straightwire instructor at The Uni-versity of Michigan. He is co-editor of anew book, Mini-Implants in Orthodon-tics: Innovative Anchorage Concepts,with Björn Ludwig and SebastienBaumgaertel, Quintessence, 2008. Hehas a financial interest in the devicesdescribed in this article.

Dr. Jay Bowman1314 West Milham AvenuePortage, MI 49024E-mail: drjwyred@aol.com

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