A Removable Orthodontic Device for the Treatment of Lingually Displaced Mandibular Canine Teeth in Young Dogs Leen Verhaert, DV\{
Sutnwary: Tl4e v,Lnlocclwsion of ti,.ngwntly d.isptaced. rnand,ibwlar cnnine teeth is a. c07,tr.- tmon ot'thod.ontic problenoin the d,orwestic dog. Sepernl treattuent wtethod,s haye been tlescribed., and. their nd'ttantages and disnd.vanta.ges ha.ye been extensively reviewed. This nrticle rl'escribes a funct'ional tecbn'ique used.'in 3B d.ogs of d.ffirent breeds for correction of the r'nnlocclusion. The techn,iqwe co,tosists of stiwulat,ing the dog to play with speciflc toys. It is n sitnph, inexpensive, non-invasive techniqwe that has a. saccess rate cuvnpa,- rable to conventionnl orthod,ontic techruiqwes for trea.tflxerct of this cononoon rualocclwsion. J Vet Dent 16(2); 69-75, 1999. lntroduction Technique The malocclusion of lingually displaced mandibu- This technique for correcting uncomplicated cases lar canine teeth is a relatively common orthodontic of lingually displaced mandibular canine teeth problem in the dog.l-o This malocclusibn may be involves stimulating the dog to play, as often as pos- due to a dental abnormality, a skeletal abnormality, sible, with specific rubber toys of an appropriate-size or a combination of both.7'8 The palatal contact of and shape. Correct diagnosis is critica-l-for success of the mandibular canine crown tips frequently causes treatment. No major jaw length discrepancy should discomfort and pain, and may lead to mucosal ulcer- be present. The diastema berween the maxillary ation, infection, and even oronasal fis6lx1ie1.7-10 third incisor and canine teeth should be wid6 Several treatment methods have been described to enough to accomodate the mandibular canine tooth correct the abnormality or to relieve the discomfort in its corre_cted position. Playing with and chewing of the animal.4,8'I0-13 Movement of the malocclud- on a suitable object forces the mandibular canine ed teeth may be undertaken using orthodontic appli- teeth into a comfortable and more normal occlusal ances: inclined plane (direct or indirect),14-18 tale- position. scoping inclined plane,l8 or active force devices The most appropriate objects ro use are toys with (expansion screw, W-wire, modified euad helix).z,a,tl a round or oval shape. Toys with ropes or handles The majority of these are fixed appliances, though should not be used, since dogs tend to take toys in removable appliances are also described. Othtr their mouth the easiest way, e.g., by the rope if it is treatment options include surgical reposition- present. The size is important. Too small a toy will ing,I3'2o,zru surgical crown reduction anil extrac- not touch both mandibular canines at the same time, fi91.8,10,r1,r3, and also might be taken too deeply into the mouth. All ofthese techniques have advantages and disad- Too large a toy (i.e., one that lies on top of the vantages) which have been reviewqd extensively.4,6,lz canine crown tips) might cause intrusive ra[her than All of them require anesthesia on at least one occa- lateral tipping pressure and might be uncomfortable, sion, with some techniques requiring multiple anes- causing the dog to give up playing. The correct size thetic episodes. of toy sits in between and just behind the canine This paper describes a very simple, inexpensive, teeth, and is larger than the distance between the animal- and owner-friendly technique for correction canine te.eth. and thus applies principally lateral pres- of lingually displaced mandibular canine teeth when sure to the reeth while the dog plays. no other sbvere malocclirsion is present. In some dogs very large toys are needed, because Additionally, the technique enhances the animal- the dog holds objects between its carnassial teeth owner bond. The technique can be described as a rather than the canine teeth. In that case the toy behavior modification tecFniqug using a removable needs to be so large that it does not fit between the orthodontic device. carnassial teeth, as this is likely to result in some
Figure l: D9g, with rubber ball (A) and dog with rubber chew toy in its mouth (B). The potential beneficial effect of the toy on lingually displaced mandibular canine teeth can be clearly seen. The toy subjects tl\e teeth to tipping pressure in a labial direction.
J. VET DENT. VoL 16 No. 2 June 1999 69 Figure 2: Case 17 at initial presentation, left lateral (A) and right lateral (B) views. Although the displacement of the left mandibular canine tooth is only moderate, clinically the situation is severe, with the tip of the crown of the mandibular canine tooth sitting in the periodontal space of the maxillary canine tooth.
degree of rostral, as well as lateral, tippurg of the In 14 dogs with no other malocclusion present, canine teeth. In selected cases, where rostral as well the mandibular canine teeth displacement had been as lateral tipping is required, carrying the toy corrected within 2 months, treatment sometimes between the carnasial teeth can be useful in some taking as little as 2 weeks. The time required for cor- cases but undesirable in others. rection was recorded for 26 dogs, and ranged from The composition and consistency of the object are 2-12 weeks. For dogs aged 5 months at the start of important. Tl"re toy should be hard rubber, slightly treatment, the time required for correction ranged deforming on chewing. Too soft a toy is unlikely to from 2-B weeks (median 3 weeks); for dogs aged SVz create enough pressure and would be rapidly months) time required was 2-6 weeks (median 4 destroyed b), chewing. Toys that are too hard or weeks); fbr dogs aged 6 months) time required was abrasive could damage the teeth. The toy should 3-4 weeks (median 3.5 weeks); for dogs aged 6Vz have a smooth surface to avoid excessive tooth wear. months, time required was 2-7 weeks (median 4 Active play for 15 minutes, 3 times per day is the weeks); for dogs aged7-9 months) time required was recommended minimum; however, longer and more 5-12 weeks (median 7 weeks). frequent episodes are prefbrable. The owner is advised to play with the dog as often as possible and to take away all other toys. Assuming a I week learning phase before the treatment becomes effec- tive,2 additibnal rveeks are needed before any bene- fit from the treatment is likely to be seen. Occlusion is checked 3 weeks following the start of treatment, then again at monthly intervals as necessary. If no movement is seen after 3 weeks, other treatment methods should be considered. Results Thirty-eight dogs, most of them of large and giant breeds, are included in this series of referral cases seen during a2-year period. The results are summa- rized in Table 1. The extent of displacement of the mandibular canine teeth has been divided into slight, moderate, and severe. Slight displacement indicates that the tips of the mandibular canine teeth contact the buccal half of the diastema between the rnaxillary third incisor and upper canine teeth. Moderate dis- placement indicates that the canine crown tips press into the palatal half of the diastema, and severe dis- placement'the is used for those dogs in which the crown tips of canine teeth impact onto the palate. Table I also includes information on the presence or absence of other malocclusions. Mandibular retrog- nathia was present in several cases and the severity has been divided into either slight (less than 3mm) or significant (more than 3mm gap between the maxillary and mandibular incisor teeth). Cases were followed for 2 weeks up to 2 years. One case was lost to lbllow-up. Long-term follow- up in most cases was done by telephone contact with Figure 3: Case 17 after 17 days of treatment, left the owner or throllgh the referring veterinarians. lateral (A) and right lateral (B) views. The No relapses were reported following use of this tech- mandibular canine crown tips have moved 4mm ruque. labially .
70 J. VET. DENT. Vol. 16 No. 2 June 1999 Figure 4: Case 24 at initial presentation, right Qase 24 four months later, left lateral (C) and lateral (A) and left lateral (B) views. right lateral (D) views.
Four dogs had retained deciduous canine teeth mandible being 2mm longer than the maxilla, the present in the mandible. The deciduous teeth were permanent mandibular canine teeth were touching extracted. The malocclusion was corrected in these the palatal sides of the maxillary third incisor teeth. four dogs. One of these dogs also had rostral The left third incisor tooth had already moved buc- (incisor) crossbite. cally, being inclined 45" compared to a normal posi- Eight dogs had slight to severe narrowing of the tion. The right third incisor tooth was still in a nor- mandible (unilateral or bilateral). In a normal occlu- mal position. To give this dog a more comfortable sion, the mandible needs to be slightly smaller than bite, the left third incisor tooth was extracted. On the maxilla. The buccal face of the mandibular first the right side, only the retained deciduous canine premolar tooth falls just palatal of the palatal face of teeth were extracted, and the dog was given a rubber the maxillary first premolar tooth. If the mandible is ball to play with. Although the left mandibular narrow as compared to the maxilla, a gap can be canine tooth seemed to be trapped behind the max- seen between the mandibular and maxillary first pre- illary third incisor tooth) it moved into a normal molar teeth when looking at the jaws in a ven- position over a period of 5 weeks. trodorsal view. The difference between slight and severe was made in an arbitrary way. The lingual dis- Discussion placement of the canine teeth in six of these dogs Lingually diplaced mandibular canine teeth are a ' was corrected in 2 rveeks to 2 months. In one, a common malocclusion, reported in many breeds.r 6 Staffordshire terrier, the lingual displacement of the Several orthodontic treatments have been canine teeth Was corrected only on the least affected described. The most widely used are inclined planes, side, and crorvn reduction was performed on the attached to the maxillary teeth) in different forms: . canine tooth on the severely affected side. In anoth- direct acrylic inclined plane,l5,rz,ta indirect acrylic or er dog, an Airedale terrier, the tooth moved 3.5mm metal inclined plane.ra'r0 In young, growing dogs in 3 weeks, and then continued to move at a rate of the use of a telescoping inclined plane is preferable, 0.5mm per month. to overcome the problem of inhibited jaw growth Eight dogs had slight or severe mandibular retro- resulting from use of lixed appliances.ro'22 These are ganthia, and these had the worst outcome in the all functional devices, which rely on the dog to cre- series of cases. Three of them, with slight mandibu- ate orthodontic force when it closes its mouth. lar retrognathism,_were corrected.in 2-3 weeks. One Active devices are also used, placed in the mandible. was moving slowly (0.5mm per month), one was Examples are expansion screws) W-wire, and modi- unilaterally corrected, and in three dogs the canine fied quad-he1ix.2,8,10,13,1e Surgical repositioning is teeth did not move. One of these dogs, an Airedale anothtr technique that has been used for movement terrier with a severely narrowed and slightly retrog- of maloccluding teet6.ra'zo'zr For these treatments nathic mandible, did'not want to play wlth any toys. no major jaw discrepancies should be present. When A combination of acrylic inclined planes attached to major jaw discrepancies are present) surgical crown the maxillary canine teeth and gingivoplasty of the reduction (including partial pulpectomy, pulp cap- maxillary third incisor-canine diastema were used to ping, and surface restoration) of the mandibular provide relief of the animal's discomfort. ianine teeth is often the best treatment, although One bull terrier with a wry bite and severe nar- extraction is another option.l0,ll {Jse ofan external rowing and retrognathism of the right mandible fixator for forward movement of mandibular canine showed no movement of the mandibular canine teeth has been described in a case of mandibular ret- tooth over a period of 2 months. One Bichon Fris6 rognathia.23 Some of these techniques are more had a malpositioned righr mandibular canine.tooth. appropriate and have fewer adverse effects than oth- The root of the mandibular right third incisor tooth eis. Fbr successful use of any orthodontic appliance, blocked any labial movement of the canine tooth, a cooperative dog and owner are necessary.4,S'10,r2 and this incisor tooth was extracted. The malposi- Good oral hygiene is necessary to reduce mucosal tioned (ectopic) canine tooth was only half erupted. inflammation around the appliance, and frequent The root was not exposed after extraction of the examination is recommended. All toys should be incisor, but the remainder of the crown (still in the removed to avoid loss or breakage of the appliance. alveolar bone) was exposed. The canine tooth In the rubber-ball technique, cooperation is also moved into normal position over a period of 4 necessary. The owner needs to actively play with the months. One mixed breed dog showed a more com- dog and the dog needs to be willing to play. In most plex malocclusion. Left mandibular and maxillary cases, when working with young dogs, interest in deciduous canine teeth were retained. With the playing is not a problem. Toys other than the round
J.VET. DENT.Vot.16 No.2 June 1999 71 a Tdble I. Clinical Features of 38 dogs with Lingually Displaced Mandibular Canine Teeth
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72 J. VET. DENT. Vol. 16 No. 2 June 1999
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* F F E B .* * F rn * F (.1 co co \o o) Gl * \o * r- ' * rn (\| d d rt' o E *{. d' * d € ! € VET. DENT. Vol. 16 No. 2 June 1999 73 or oval rubber chew toy should be taken away, and After orthodontic treatment) a retention period several toys,inay induce-more play activity tt .i-""iy is one. usually necessary to prevent return ofthi tooth to its In m.ukiple dog househojds, many ioy, rn"y bt tormer posrtlon. necessary because ^V\4ren using conventional ortho_ tlie older dogs steai toy, fr"i" u oonuc.apptlances fo1 younger one. treatment, a retention period is generally considered necessary. In the casb of lin_ All the commonly used orthodontic techniques gLta.lty. cllsplaced mandibular canine teeth, a retention require multiple anesthesias with the associated'iisk peri.od is usually nor necessary since the natural den_ and expense. The rubber toy technique is inexpen_ tat lnterlock retains the canine teeth in t]-re desired sive and avoids the necessiry ilf It wbuld position.4,8,r0,r3 With be advisable to obtain full'pre-"n"sth'iria. the technique deicribed in a"a p*1_lr"atment this article, additional rerenrion i, p.o"iJ.J-bt;";_ impres.sions and radiographi, as with'any-orthodon_ tinued use of the toy. It appears iirut bur some owners are not th.r. ii tittle l: !.:hliqye, ;lti;t;; risk of overcorrection (labioversion) oF-the canine have rheir dogs. ane.sthedsed just to take impressi"ons. teeth. This did not happen in any bf tfr. ag As a compromise, hard wax bite wafers can be ;"rii, used he.re, even whin very lar[e toys wcre pro_ to record crown tip positions in most conscious :,.f:jl.q\.loeo long-term. dogs. .Photographs .an be taken to."."ia th. .*t.rri wirh any ot malocclusion, fu technique, correcr diagnosis is critical taking a rostral, left and right view for^ success ofeach of treatment. No major jaw discreoancv case. should be presenr. rubber .ln the .rr. o'f , ii""i.ly i.'t _The ball technique has several other maior nathic. mandible, the ourward "gl advantages.as compa.red to working movemeni of th"e *rt,.in. pi.'"i_ mandlbular canine tooth is inhibired by rhe maxillary ously described appliances, which lan cause several canine '*. problems.2.4.6.8,t0.t2 tooth. In less severe cases, t.inniqu! In young dogs, jaw growth does seem to work might be inhibited . if a very large rubbeiU"tt ls ,rr'eJ by afplian"ces tE"i'iemJrrt th. .1" tip the canine te6th ,iot and'iniiior teeth :p ], only laterally, bui laxilllJV..canine in fi*.J p"rt_ also rosrrally to a certain exrent. The diaiiema sep.o.ru.22 When teeth are not fully erupted ai the berw.een maxillary third incisor and canine teeth time a fixed appliance is placed, ;t ii titeli ttrrt .onl needs rvide trnued eruprion to be enough to accomodate the will result in displacement of the mandibular canine teerh. applrance.s Pressure from applianies might lead to Lingually displaced mandibular soft tissue trauma. Good . canine teeth have oraihygiene iiri"t -urra"- been described as being primarily f"l successfi_rl ourcome caused by reten_ l"ly whe"n using ihe rubber tion of deciduous canind 1s.dr.o,r.i,rs Datl techntque. (Jral soft tissue In this-mandibular ieries of traumi from pres_ 38 cases, only four dogs had retained su.r;, inflammation. and ulceration are very ,nfil;ly oectduous canlne teeth. More than wrth this technique . unless rhe dog 50% of the dogs is allergic to rub_ reported here had a cliniqally clctecrable t."gif, Der.. law growth is not inhibited as is seen with some or width abnormality. ;"* ot the fixed applianccs. Skel'etal malocclirsions ?re considered inherited unless a developmintal cause , People obiiin dogs for their pleasure, but often can reliably cto nor spehd ,be identified.8 Owners bf tt es. aogs enough qualiry time with them. In a need ro be advised world where'ume about the heritabiliry of thls is money and work is often stress_ condition, and r_o informed that the treated a,ig,houd $1, time is left for th. .o-p*iorr-that *a, not be bred. intended to relieve stress in tne nr'.t pta.i. I often To date.,,there have dogs that are been no reports of the fre_ f-!! Vounq bored aid lazy. Th; quency with which lingually displaced moment the owner starts ro actively play canine teeth with the as jaw growth contiiues. Early dog, th9 dog's character changes :",:,1..1 fixed-device drimlJlally;;^; orthodonuc treatment is not recommended.6,s,r0,22 strong bond berween owner-and dog is formea. AJthough treatment as described here (Jnce owners are used.to playing,_they -av not h"u. often will go been necessary fbr some of these on doing so because theyied.t#'U."!ni""a dogs, tLrere is no .;i"i)^ reason not to encourage the owner to play with the ment for the dog and themselves. dog. qlay ti.pe required for this technique _ ffnimum is The success of this very simple and functional not I 74 J. VET. DENT Vot. 16 No. 2 June 1999 1.3. Shioo A. Fahrenkrue P: Practitioners' Gwid'e to Veterinory Aknowledgements oe n t;stii, I st ed. BeverlliHills: Dr Shipps Laboratories,.l 992' The authorlhanks D. A' Crossley for his advice l,i. C;i"" S: Correcti6n of a traumatic malocclusion involving while writing thid article. thi canine teeth in t dog. Brit Wt Dent Assoc Joarnnl (4.) 1994' I 5. 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Fulford M: A review of treatment modalides for ^"-n"i.*,dtetl Swed"bert louinal swppl 36' I986. -uf"iif"ii""t involving the mandibular canine teeth of the dog' Brit Wt Dent Assoc Joirndl(41,199I. i2. Holrt o- S, Fr-ost P, Gammon R Dental Orthodontics' In: Author lnformation Utttiiniry Ot"inl Techniques. Philadelphia: \4lB Saunders, 339- From Dr Leen Verhaert, G.Van der Lindenlaan 15, 387, 1992. B 2570 Duffel. Belgium. 75 J. VET. DENT. Vol. 16 Na. 2 June 1999 t--