METHODS & TECHNICAL Advances

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1 METHODS & TECHNICAL Advnces Ahmet Keles, DDS, DMSc 1 KELES KEYLESS EXPANDER: A NEW APPROACH FOR RAPID PALATAL EXPANSION Mxillry trnsverse constriction is mong the most common mlformtions in orthodontics. Tretment usully requires rpid pltl expnsion with nded or onded expnders fter eruption of the mxillry first molrs. The history of pltl expnsion goes ck nerly 150 yers nd hs retined its populrity ever since. However, ptient/gurdin complince in ctivting the screw with key is required. Becuse it is difficult to see the hole on the screw, it is hrd to insert the key through the hole. Furthermore, the chnce of injuring the pltl mucos with the pointed wire key nd the risk of swllowing or spirting the key re common undesired outcomes, nd oth occur in dily orthodontic prctice. To overcome these unwnted incidences nd mke pltl expnders more ptientfriendly, new design of pltl expnder hs to e developed for sfe, rpid, nd effective expnsion with minimum ptient coopertion. A newly developed keyless expnder hs uilt-in ctivtion rm, which ptients cn ctivte themselves. In ll 4 treted cses with keyless expnder, expnsion ws effectively chieved in short period of time. World J Orthod 2008;9: Associte Professor, Deprtment of Developmentl Biology, Advnced Orthodontic Grdute Progrm, Hrvrd School of Dentl Medicine, Boston, Msschusetts, USA. CORRESPONDENCE Dr Ahmet Keles Deprtment of Developmentl Biology Advnced Orthodontic Grdute Progrm Hrvrd School of Dentl Medicine 188 Longwood Avenue Boston, MA USA E-mil: keles@post.hrvrd.edu Rpid pltl expnsion (RPE) dtes to 1860 when Dr Angell plced screw pplince etween the mxillry premolrs of 14.5-yer-old girl nd widened her rch qurter of n inch in 2 weeks. 1 The ptient ws provided key nd instructed to keep the shft s uniformly tight s possile. At the end of 2 weeks, the jw ws widened enough to leve spce etween the 2 centrl incisors. This finding cnnot e supported with rdiogrphs, s X-rys hd yet to e discovered. The mechnism of ction of RPE ws clrified in 1950s studies on cts, pigs, nd monkeys. 2 4 These studies showed tht midpltl suture ws opened using this technique s ppliction of intermittent force. These studies were lter supported y Biedermn, 5 Brossmn et l, 6 Chcons nd Cputo, 7 Tnne et l, 8 Melsen, 9,10 nd Murry nd Clell 11 who performed studies on dry skulls nd humn cdvers tht indicted tht ge is n importnt fctor when considering the effect of RPE on crniofcil structures. Within the pst 10 yers, 2 types of RPE pplinces hve een used in orthodontic prctice: onded-type crylic cp splint RPE nd the nded-type (nding the first molrs nd premolrs) RPE pplince. In oth cses, key is required to ctivte 407

2 METHODS & TECHNICAL ADVANCES WORLD JOURNAL OF ORTHODONTICS Fig 1 Design of the keyless expnder, front view. Fig 1 Design of the keyless expnder, side view. Fig 1c Keyless expnder, front view. Fig 1d Keyless expnder, ck view. c d Fig 2 mouth. Applince cemented in the Fig 2 A ptient ctivtes the screw with fingertip. the pplince. The key hs either plstic hndle to ese the ctivtion process or short wire key with piece of dentl floss ttched to prevent the ptient swllowing or spirting it. 12 Nevertheless, ccidentl swllowing of the key is still reported, 13,14 which, mong other things, cretes liility issues. There is desperte need for sfe, ptient-friendly expnder to reduce tretment time nd increse tretment efficiency. APPLIANCE DESIGN The pplince consists of vriety of components (US ptent no. US 7,074,036 B1). Insted of using key to turn the screw, the screw ccommodtes wheel with uilt-in, rtchet-like ctivtion rm (Figs 1 to 1d). The rm utomticlly springs ckwrd with the help of nickeltitnium spring mechnism fter finger press. The wheel s housing consists of 3 qurtocirculr indents nd ccommodtes pin tht ctively turns the screw in unidirectionl fshion nd pssively springs ck. The ptient is instructed to push the rm ckwrd once dy (Figs 2 nd 2), nd ech turn pplies 0.2 mm of expnsion. Bsed on the mount of expnsion needed, the ptient is instructed to turn the rm for certin numer of dys. CASE 1 A femle 14 yers 6 months of ge in the permnent dentition ws dignosed with ilterl mxillry constriction of 5 mm. She required n RPE pplince to resolve skeletl nd dentl trnsverse discrepncy. We nded the mxillry first molrs nd premolrs nd took impressions for construction of keyless expnder. The pplince ws cemented in plce nd the ptient instructed to turn it once dy. She ws seen 22 dys lter to monitor the expnsion. The results re presented in Figs 3 nd 3 nd Figs 4 nd 4. CASE 2 A femle 13 yers 5 months of ge in permnent dentition ws dignosed with ilterl mxillry constriction of 4.5 mm. She required n RPE pplince to resolve skeletl nd dentl trnsverse discrepncy. We nded the mxillry first molrs nd took impressions for construction of keyless expnder. The pplince ws cemented on the first molrs nd onded to the first premolrs. The ptient ws instructed to turn it once dy nd seen 20 dys lter to monitor the expnsion. The results re presented in Figs 5 nd 5 nd Figs 6 nd

3 VOLUME 9, NUMBER 4, 2008 Keles Fig 3 Fig 3 Cse 1, initil frontl view. Cse 1, initil occlusl view. Fig 4 Cse 1, midtretment frontl view (note the centrl distem). Fig 4 Cse 1, midtretment occlusl view. Fig 5 Fig 5 Cse 2, initil frontl view. Cse 2, initil occlusl view. Fig 6 Cse 2, midtretment frontl view (note the correction of the posterior crossite in the molr region). Fig 6 view. Cse 2, midtrement occlusl 409

4 METHODS & TECHNICAL ADVANCES WORLD JOURNAL OF ORTHODONTICS Fig 7 Fig 7 Cse 3, initil frontl view. Cse 3, initil occlusl view. Fig 8 Cse 3, midtretment frontl view (note the midline distem nd correction of the crossite in the right molr region). Fig 8 Cse 3, midtretment occlusl view (note the improvement of the rch symmetry). Fig 9 Fig 9 Cse 4, initil frontl view. Cse 4, initil occlusl view. Fig 10 Cse 4, midtretment frontl view (note the midline distem nd correction of the crossite in the molr region). Fig 10 Cse 4, midtretment occlusl view. 410

5 VOLUME 9, NUMBER 4, 2008 Keles CASE 3 A femle 14 yers 1 month of ge in permnent dentition ws dignosed with unilterl mxillry constriction of 7 mm. She required n RPE pplince to resolve skeletl nd dentl trnsverse discrepncy. We nded her mxillry first molrs nd took impressions for construction of keyless expnder. The pplince is cemented on the first molr nd onded to the first premolr. The ptient ws instructed to turn the screw once dy nd ws seen 24 dys lter to monitor the expnsion. The results re presented in Figs 7 nd 7 nd Figs 8 nd 8. CASE 4 A femle 12 yers 6 months old in permnent dentition ws dignosed with ilterl mxillry constriction of 5 mm. She required n RPE pplince to resolve skeletl nd dentl trnsverse discrepncy. We nded the mxillry first molrs nd took impressions for the construction of the newly developed expnder. The pplince is cemented on the first premolrs nd onded to the first premolrs. The ptient ws instructed to turn the screw once dy nd ws seen 14 dys lter to monitor the expnsion. The results re presented in Figs 9 nd 9 nd Figs 10 nd 10. CONCLUSION The results of the ove cses show tht the keyless expnder is n effective mens to chieve mxillry expnsion with minimum ptient coopertion. The conventionl expnders require key for ctivtion; if you do not complete the one-qurter turn, the next hole on the screw does not pper, therey mking it impossile for the ptient to proceed ctivtion. The keyless expnder does not require key, nd the ptient needs only turn the rm once dy with finger tip. The other dvntge is tht fter completion, the screw does not unwind ecuse of its design. The uilt-in rm llows for esy ctivtion of the screw without the risk of dropping the key down ptient s throt or ctivting the ptient s gg reflex. The risks of spirtion, swllowing, nd injuring the plte hve een eliminted. In this cse report, the first phse (expnsion) tretment ws completed in n verge of 3 weeks, enling the second phse to egin without dely. ACKNOWLEDGMENTS The uthor would like to thnk Dr Edwrd Seldin, Dr Donld Nelson, Dr Doil Kim, nd Dr Ping-Lin Ben Chung for their contriutions. REFERENCES 1. Angell EC. Irregulrities of teeth nd their tretment. Sn Frncisco Medicl Press 1860;1: Denne EF. A cephlometric nd histologic study of the effect of orthodontic expnsion of the midpltl suture of the ct. Am J Orthod 1958;44: Hs AJ. Gross rection to the widening of the mxillry dentl rch of the pig y splitting of the midpltl suture. Am J Orthod 1959;45: Strnch H, Byne D, Clell J, Sutelny JD. Fcioskeletl nd dentl chnges resulting from rpid mxillry expnsion. Angle Orthod 1966;36: Biedermn W. Rpid correction of Clss 3 mlocclusion y midpltl expnsion. Am J Orthod 1973;63: Brossmn RE, Bennett CG, Merow WW. Fcioskeletl remodelling resulting from rpid pltl expnsion in the monkey (Mcc cynomolgus). Arch Orl Biol 1973;18: Chcons SJ, Cputo AA. Oservtion of orthopedic force distriution produced y mxillry orthodontic pplinces. Am J Orthod 1982;82: Tnne K, Schdev R, Miysk J, Ymgt Y, Skud M. A study of strin nd stress levels in the circummxillry suturl systems during rpid mxillry expnsion: An pproch using oth the strin guge technique nd the theoreticl stress nlysis. J Osk Univ Dent Sch 1986;26: Melsen B. Pltl growth studied on humn utopsy mteril. A histologic micrordiogrphic study. Am J Orthod 1975;68: Melsen B. A histologicl study of the influence of suturl morphology nd skeletl mturtion on rpid pltl expnsion in children. Trns Eur Orthod Soc 1972: Murry JM, Clell JF. Erly tissue response to rpid mxillry expnsion in the midpltl suture of the rhesus monkey. J Dent Res 1971;50: McNmr JA. Brudon WL. Orthodontics nd Dentofcil Orthopedics, ed 2. Ann Aror: Needhm Press, Nzif MM, Redy MA. Accidentl swllowing of orthodontic expnsion pplince keys: Report of two cses. ASDC J Dent Child 1983;50: Sfondrini MF, Cccifest V, Len A. Accidentl ingestion of rpid pltl expnder. J Clin Orthod 2003;37: