Originl Article Evlution of mxillry centrl incisors on the noncleft nd cleft sides in ptients with unilterl cleft lip nd plte Prt 1: Reltionship etween root length nd orthodontic tooth movement Ay Med-Iino *; Knko Mrutni *; Minmi Furukw ; Shoko Nkgw ; Sngho Kwon ; Toshiro Kie c ; Mshiro Tezuk c ; Norifumi Nkmur d ; Shouichi Miywki e ABSTRACT Ojectives: To mesure the root lengths of mxillry centrl incisors (U1) nd evlute the reltionship mong U1 root length, tooth movement, nd type of tretment pplince in ptients with unilterl cleft lip nd plte over long-term follow-up period. Mterils nd Methods: Occlusl rdiogrphs of 30 ptients with unilterl cleft lip nd plte, cquired less thn 6 months efore secondry lveolr one grfting (SBG, T1) nd fter edgewise tretment (T2), were mesured for U1 root length (R1 nd R2, root lengths t T1 nd T2, respectively). Frontl nd lterl cephlometric rdiogrphs cquired t eruption of U1 (T0), T1, nd T2 were evluted to determine the inclintion nd position of U1. Results: The verge vlues of R1 nd R2 on the cleft side were significntly lower thn those on the noncleft side. Frontl cephlometric nlysis reveled tht the horizontl distnce of the root pex from the medin verticl line t T0 on the cleft side ws significntly smller thn tht on the noncleft side nd ws correlted with short U1 root length on the cleft side. On the other hnd, R1 in ptients treted with mxillry protrction pplinces etween T0 nd T1 ws significntly shorter thn tht in ptients without mxillry protrction pplinces. However, none of the chnges in cephlometric mesurements were correlted with root length. Conclusions: In ptients with unilterl cleft lip nd plte, the short root length of cleft-djcent centrl incisors might e ssocited with the horizontl position of the root pex. In ddition, orthodontic tretment with mxillry protrction pplince efore secondry lveolr one grfting might e ssocited with short U1 root length. (Angle Orthod. 2017;87:855 862.) KEY WORDS: Root lengths of mxillry centrl incisors; UCLP; orthodontic tooth movement; Long-term follow-up * The first two uthors contriuted eqully to this study. Assistnt Professor, Field of Developmentl Medicine, Helth Reserch Course, Deprtment of Orthodontics nd Dentofcil Orthopedics, Grdute School of Medicl nd Dentl Sciences, Kgoshim University, Kgoshim, Jpn. Postgrdute Student, Field of Developmentl Medicine, Helth Reserch Course, Deprtment of Orthodontics nd Dentofcil Orthopedics, Grdute School of Medicl nd Dentl Sciences, Kgoshim University, Kgoshim, Jpn. c Assistnt Professor, Field of Orl nd Mxillofcil Rehilittion, Advnced Therpeutics Course, Deprtment of Orl nd Mxillofcil Surgery, Grdute School of Medicl nd Dentl Sciences, Kgoshim University, Kgoshim, Jpn. d Professor nd Deprtment Chir, Field of Orl nd Mxillofcil Rehilittion, Advnced Therpeutics Course, Deprtment of Orl nd Mxillofcil Surgery, Grdute School of Medicl nd Dentl Sciences, Kgoshim University, Kgoshim, Jpn. e Professor nd Deprtment Chir, Field of Developmentl Medicine, Helth Reserch Course, Deprtment of Orthodontics INTRODUCTION In ptients with cleft lip nd plte (CLP), some teeth, especilly mxillry incisors, often develop short roots. 1 Those short roots might complicte tretment plnning in orthodontic mngement or nd Dentofcil Orthopedics, Grdute School of Medicl nd Dentl Sciences, Kgoshim University, Kgoshim, Jpn. Corresponding uthor: Dr Shouichi Miywki, Field of Developmentl Medicine, Helth Reserch Course, Grdute School of Medicl nd Dentl Sciences, Deprtment of Orthodontics nd Dentofcil Orthopedics, 8-35-1 Skurgok, Kgoshim, Kgoshim 890-8544 Jpn (e-mil: miywki@dent.kgoshim-u.c.jp) Accepted: July 2017. Sumitted: Mrch 2017. Pulished Online: Septemer 14 2017 Ó 2017 y The EH Angle Eduction nd Reserch Foundtion, Inc. DOI: 10.2319/031317-188.1 855
856 MAEDA-IINO, MARUTANI, FURUKAWA, NAKAGAWA, KWON, KIBE, TEZUKA, NAKAMURA, MIYAWAKI prosthodontics, which is mjor concern for orthodontists. Aprt from short roots, severl studies hve found tht ptients with CLP lso exhiit delyed root development reltive to norml reference popultions. 1 3 The roots of the mxillry incisors (U1) in ptients with CLP re significntly shorter thn those in ptients without CLP, 1 which suggests tht genetic fctors might ply role in development of short-rooted teeth. On the other hnd, it hs een reported tht root development in cleft-djcent lterl incisors is delyed reltive to tht on the noncleft side 4,5 nd tht root resorption on the cleft side is higher thn tht on the noncleft side. 4 Surgicl cleft repir results in firosis nd reduced lood supply, cusing dmge to developing tooth uds in the cleft re. 6 Mechnisms controlling dentl development re highly influenced y the sme etiologicl fctors tht influence cleft formtion. 7 However, previous studies hve not evluted root development t the sme tretment stge or in ptients of similr ge. Therefore, the cuses of shortness of dentl roots nd root resorption in ptients with CLP hve yet to e demonstrted. Moreover, the reltionship etween root length nd the position or movement of teeth upon orthodontic tretment is yet uncler. This study imed to (1) evlute root length nd tooth position of U1 on the noncleft nd cleft sides in ptients with unilterl CLP (UCLP), (2) compre cephlometric mesurements on the noncleft nd cleft sides, nd (3) evlute the reltionship etween root length nd tooth position following orthodontic tretment using different tretment pplinces. MATERIALS AND METHODS This study ws pproved y the Kgoshim University Ethics Committee (#519, 589, 661). Ptients Among consecutive ptients with CLP treted t the Deprtment of Orthodontics, Kgoshim University Medicl nd Dentl Hospitl, Kgoshim, Jpn, etween 1983 nd 2015, 30 ptients who met the inclusion nd exclusion criteri were enrolled (Tle 1). The inclusion criteri were the presence of complete UCLP, orthodontic nd surgicl tretment for UCLP t the hospitl, nd similr orthodontic tretment in the cleft re in ccordnce with the following protocol (N ¼ 66): (1) lignment of the cleft-djcent U1 y lingul inclintion or rottion, eing creful to void movement of the roots into the cleft re, nd expnsion of the mxillry rch efore secondry lveolr one grfting (SBG) in cses where the mxillry dentl rch displyed constriction of the minor segment; (2) SBG during the mixed dentition; (3) initition of orthodontic Tle 1. Sex nd Age Distriution of Ptients t Ech Evlution Period nd Men Oservtion Period Vrile n/n or Men 6 SD Sex, mle/femle, N) 16/14 Age t T0 (y) 7.80 6 0.87 t T1 (y) 10.50 6 1.51 t T2 (y) 16.49 6 1.70 Oservtion period (y) 8.70 6 1.78 T0 indictes t eruption of centrl incisors; T1, t less thn 6 months prior to secondry one grfting; T2, fter edgewise tretment. SD, stndrd devition. tretment, including edgewise tretment in the grft re, with tretment for cleft-djcent teeth t 3 months post-sbg in cses requiring tooth movement into the grft re; nd (4) edgewise tretment of the mxillry nd mndiulr permnent teeth. The exclusion criteri were tretment involving mxillry orthognthic surgery, unvilility of rdiogrphs required for this study, the presence of cleft-djcent lterl incisors or cleft-djcent supernumerry teeth in the mjor segment, root pex of U1 not closed efore SBG (Noll developmentl stges 8, 9), congenitlly missing U1, nd crown nd root length not mesurle (eg, when the root pex ws not imged or the crown ws fitted with lrge dentl prostheses; N ¼ 36). Mesurement of Root Length Occlusl rdiogrphs of the mxillry nterior occlusion, including the cleft re, were cquired y rdiologists using stndrd rdiologic technique (long-cone technique, with root direction perpendiculr to the pltine midline). Imges cquired less thn 6 months efore SBG (T1) nd fter edgewise tretment (T2) were evluted. The outlines of U1 from occlusl rdiogrphs were trced on cette sheets. Crown height nd root length were defined s shown in Figure 1 9 nd mesured using digitl clipers. Correction fctors (CF) were clculted on the sis of crown heights t T1 nd T2 (C1 nd C2, respectively) s follows: CF ¼ C2/C1. Although root length t T2 (R2) ws determined in ccordnce with the originl mesurement, tht t T1 (R1) ws clculted s follows: Originl mesurement root length t T1 3 CF. To vlidte the ccurcy of occlusl rdiogrph mesurements, the method errors (ME) for occlusl rdiogrph mesurements were compred with those of peripicl rdiogrph mesurements of U1 in 15 ptients who hd undergone imging y oth methods during the sme period. In ddition, inter- nd intrexminer (AM nd KM) reproduciility nd reliility of root length mesurements were ssessed on the sis of ME. U1 in these occlusl nd peripicl rdiogrphs were retrced fter minimum intervl of 2 months. The ME for dentl root length ws clculted using the
ROOT LENGTH OF U1 IN PATIENTS WITH UCLP 857 Figure 1. Mesurement of crown height nd root length. Line, longitudinl xis long the root cnl from the root pex to the incisl edge; line c, line drwn through the mesil nd distl sides of the cementoenmel junction; nd point m, intersection of lines nd c. Crown height nd root length were mesured long line from the incisl edge nd root pex, respectively, to point m. following Dhlerg formul 10 : qffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffiffi Xðd ME ¼ 2 =2nÞ; where d is the intr- nd interexminer difference in root length, nd n is the numer of evluted teeth. The MEs for the inter- nd intrexminer reliility of root length mesurements were 0.25 nd 0.59 for occlusl rdiogrphs nd 0.31 nd 0.45 for peripicl rdiogrphs, respectively. There were no significnt differences in originl root-length mesurements etween occlusl nd peripicl rdiogrphs (mtched pired t- test). Evlution of Frontl nd Lterl Cephlometric Rdiogrphs Figure 2. Frontl cephlometric nlysis. A, noncleft side; B, cleft side;, long-xis ngle (8);, U1-root VL distnce (mm). U1 indictes mxillry incisor; VL, verticl line; HL, horizontl line; CA, centrl incisl xis. Cephlometric rdiogrphs of ll ptients cquired t the eruption of U1 (T0), T1, nd T2 were evluted for dentofcil morphologicl chrcteristics. The rdiogrphs were trced y the uthors, nd the ngles were determined using WinCeph 9.0 softwre (Compudent, Kolenz, Germny). Distnces were mesured using digitl clipers. Figure 2 presents the frontl cephlometric vriles evluted. Two reference lines, horizontl line (HL) connecting the right nd left ltero-oritle points nd verticl line (VL) through the center of the crist glli perpendiculr to HL, were trced for the verticl nd horizontl mesurements. The internl ngle etween HL nd centrl incisl xis CA ws defined s the U1 xis ngle (, Figure 2). The horizontl distnce etween the VL nd the root pex of U1 ws defined s the U1-root VL distnce (, Figure 2). The inclintion nd position of U1 were determined y lterl cephlometric nlysis (Figure 3). Axil proclintion of U1 to the nterior crnil se ws Tle 2. Comprison of Centrl Incisor Root Length Between the Cleft nd Noncleft Sides nd Results of Fixed-Effects Anlysis Mesurement Noncleft Side, n ¼ 30 Cleft Side, n ¼ 30 Fixed Effects Noncleft or Cleft Period, T1 nd T2 Period, T1 nd T2 Noncleft or Cleft 3 Adjusted Men Adjusted Men P Vlue F Vlue P Vlue F Vlue P Vlue F Vlue P Vlue Root length (mm) T1 14.46 12.81.003* 15.628,.001*** 10.747,.001*** 0.075 NS T2 13.07 11.63.010* P vlue, T1 vs T2.013*.036* P vlues derived using generlized liner model with ech ptient eing considered s the covrite. Indictes significnce t P,.05 fter Bonferroni djustment for multiple comprisons. NS indictes not significnt. T1, less thn 6 months prior to secondry one grfting; T2, fter edgewise tretment. *P,.05; ***P,.001.
858 MAEDA-IINO, MARUTANI, FURUKAWA, NAKAGAWA, KWON, KIBE, TEZUKA, NAKAMURA, MIYAWAKI Figure 4. Occlusl rdiogrphs showing centrl incisors efore secondry lveolr one grfting (T1) nd fter edgewise tretment (T2) in ptient with unilterl cleft lip nd plte on the left side. Figure 3. Lterl cephlometric nlysis., U1 SN ngle (8);, U1 NA ngle (8); c, U1-root NA distnce (mm). U1 indictes mxillry incisor; SN, sell nsion; NA, nsion. determined y the ngle etween the long xis of U1 (U1 long-xis line) nd the sell-nsion (SN) plne (U1 SN ngle;, Figure 3). According to the Steiner nlysis, the reltionship etween U1 nd nsion (NA) line (line from NA to point A) indictes the reltive protrusion of teeth. The distnce etween the U1 root pex nd the NA line (U1-root-NA distnce; distnce c, Figure 3) nd the ngle etween the long xis of U1 nd the NA line (U1 NA ngle;, Figure 3) were determined. For the ssessment of intrexminer reproduciility nd reliility of the mesurements, 30 ech of rndomly selected frontl nd lterl cephlometric rdiogrphs (T0, T1, nd T2, 10 ech) were retrced fter minimum intervl of 2 months. The evlution of discrepncies in mesurements etween the originl nd retrced rdiogrphs (mtched pired t-test) reveled no sttisticlly significnt differences. Evlution of Orthodontic Applinces Used Most of the ptients received tretment with some orthodontic pplince such s mxillry protrction pplince (MPA), rpid mxillry expnsion, or qud helix efore edgewise tretment. Dt regrding the type of pplince were otined from medicl records. It ws lso investigted whether ech of the ptients did or did not receive ny of the three types of pplinces. Sttisticl Anlysis Mesurements (R1, R2, nd cephlometric prmeters) recorded on the noncleft nd cleft sides t ech time point were compred using generlized liner models djusted for mesurement period nd individul (ech ptient) effects. Sttisticl significnce ws set t P,.05 fter Bonferroni djustment for multiple comprisons. The liner mixed model pproch for longitudinl comprison cross time points nd vrying dt hierrchies ws used (highest-level hierrchy: ptients or tretment pplinces used; next level down: cleft/noncleft side or root length nd cephlometric mesurements on ech side). The proility of significnce ws clculted for ech comprison. Sttisticl tests were performed using SPSS version 24.0 for Windows (IBM, Armonk, N.Y.). RESULTS Both R1 nd R2 on the cleft side were significntly shorter thn those on the noncleft side (P ¼.003 nd.010, respectively, Tle 2). Figure 4 presents occlusl rdiogrphs of typicl cse of UCLP. On oth sides, R2 ws significntly shorter thn R1. However, there ws no sttisticlly significnt chnge in the root length mesurement over time on the noncleft side (P. 0.05, Tle 2), which indicted tht there ws no significnt difference in root resorption from T1 to T2 etween the two sides. Therefore, the next step investigted the reson why R1 on the cleft side ws shorter thn tht on the noncleft side. Almost ll frontl nd lterl cephlometric mesurements on the cleft side differed significntly from those on the noncleft side t ech period (Tle 3). There ws no sttisticlly significnt chnge in cephlometric mesurements over time on the noncleft side (Tle 4), which indicted tht there ws no significnt difference in tooth movement from T0 nd T1 etween the two sides. However, the sttisticlly significnt U1-root-VL distnce t T0 3 noncleft for the R1 indicted differentil tooth position in cephlometric mesurements ccording to the side (noncleft or cleft side; P ¼ 0.044; Tle 5). The effects of orthodontic tretment pplinces on R1 were evluted. The MPA significntly ffected the R1; however, other pplinces nd ech pplince 3
ROOT LENGTH OF U1 IN PATIENTS WITH UCLP 859 Tle 3. Comprison of Cephlometric Mesurements Between the Cleft nd Noncleft Sides nd Among Different Periods Mesurements Noncleft Side, n ¼ 30 Adjusted Men Cleft Side, n ¼ 30 Adjusted Men P Vlue Frontl cephlometric nlysis U1-xis ngle (8) T0 90.77 72.05,.001*** T1 94.48 72.60,.001*** T2 94.27 81.66,.001*** P vlue, T0 vs T1 NS NS P vlue, T1 vs T2 NS,.001*** U1-root VL distnce (mm) T0 5.74 0.63,.001*** T1 5.61 0.08,.001*** T2 4.84 2.16,.001*** P vlue, T0 vs T1 NS NS P vlue, T1 vs T2 NS,.001*** Leterl cephlometric nlysis U1 SN ngle (8) T0 91.11 85.70.013* T1 94.51 90.30 NS T2 101.63 101.43 NS P vlue, T0 vs T1 NS NS P vlue, T1 vs T2.003**,.001*** U1 NA ngle (8) T0 14.02 7.95.004** T1 17.39 13.19.045* T2 26.83 25.62 NS P vlue, T0 vs T1 NS.035* P vlue, T1 vs T2,.001***,.001*** U1-root NA distnce (mm) T0 7.10 5.01,.001*** T1 5.57 4.40.007** T2 5.57 4.47.007** P vlue, T0 vs T1.007** NS P vlue, T1 vs T2 NS NS U1 indictes centrl incisor; T0, t eruption of U1; T1, less thn 6 months prior to secondry one grfting; T2, fer edgewise tretment; VL, verticl line; SN, sell nsion; NA, nsion-point A. P vlues derived using generlized liner model with ech ptient eing considered s the covrite. Indictes significnce t P,.05 fter Bonferroni djustment for multiple comprisons. NS indictes not significnt. *P,.05; **P,.01; ***P,.001. Tle 5. Reltionship Between Cephlometric Mesurements on the Noncleft or Cleft Side t T0 nd Root Length t T1 Fixed Effects Root Length t T1 (R1) F Vlue P Vlue Noncleft or cleft side 0.279 NS U1 xis ngle t T0 (8) 0.047 NS U1-root VL distnce t T0 (mm) 1.299 NS U1 SN ngle t T0 (8) 0.045 NS U1 NA ngle t T0 (8) 0.172 NS U1-root NA distnce t T0 (mm) 0.011 NS U1 xis ngle t T0 3 noncleft side 0.810 NS U1-root VL distnce t T0 3 noncleft side 4.234.044 c * U1 SN ngle t T0 3 noncleft side 1.199 NS U1 NA ngle t T0 3 noncleft side 3.879 NS U1-root NA distnce t T0 3 noncleft side 1.423 NS U1 indictes centrl incisor; T0, t eruption of U1; T1, less thn 6 months prior to secondry one grfting; VL, verticl line; SN, sell nsion; NA, nsion-point A. P vlues derived using the mixed model pproch. NS indictes not significnt. c The estimted vlue ws 0.742 (stndrd error, 0.36) when the U1-root VL distnce on the noncleft side ws compred with tht on the cleft side. *P,.05. noncleft did not (Tle 6). There ws no sttisticlly significnt chnge in cephlometric mesurements over time on the ptients treted without MPA (Tle 7), which indicted tht there ws no significnt difference in tooth movement from T0 to T1 etween with or without MPA. Ptients treted with MPA exhiited significntly shorter R1 in ll U1 on the noncleft side thn did ptients treted without MPA (P ¼.013 nd.035, respectively, Tle 8); there ws no significnt difference in R1 on the cleft side etween the two groups of ptients. In ptients treted without MPA, R1 on the cleft side ws significntly shorter thn tht on the noncleft side (P ¼.005, Tle 8). In contrst, in ptients treted with MPA, there ws no significnt difference in R1 etween the two sides (Tle 8). Tle 4. Results of Fixed-Effects Anlysis of Cephlometric Mesurements Noncleft or Cleft Fixed Effects Period, T0 nd T1 Noncleft or Cleft 3 Period, T0 nd T1 Mesurements F Vlue P Vlue F Vlue P Vlue F Vlue P Vlue Frontl cephlometric mesurements U1 xis ngle (8) 280.181,.001*** 3.091 NS 0.196 NS U1-root VL distnce (mm) 430.318,.001*** 0.498 NS 1.374 NS Lterl cephlometric mesurements U1 SN ngle (8) 13.763,.001*** 9.519.003** 0.218 NS U1 NA ngle (8) 17.168,.001*** 12.034.001** 0.570 NS U1-root NA distnce (mm) 29.885,.001*** 11.206.001** 1.800 NS U1 indictes centrl incisor; T0, t eruption of U1; T1, less thn 6 months prior to secondry one grfting; VL, verticl line; SN, sell nsion; NA, nsion-point A. P vlues derived using the mixed model pproch. NS indictes not significnt. **P,.01; ***P,.001.
860 MAEDA-IINO, MARUTANI, FURUKAWA, NAKAGAWA, KWON, KIBE, TEZUKA, NAKAMURA, MIYAWAKI Tle 6. Reltionship Between Tretment Applinces on the Noncleft or Cleft Side nd Root Length t T1 DISCUSSION Fixed Effects Root Length t T1 (R1) F Vlue P Vlue Treted with MPA, N ¼ 12 5.90.021* QH, N ¼ 22 1.30 NS RME, N ¼ 7 1.23 NS Tretment with MPH on the noncleft side c 2.63 NS Tretment with QH on the noncleft side c 1.37 NS Tretment with RME on the noncleft side c 0.10 NS T1 indictes less thn 6 months prior to secondry one grfting; MPA, mxillry protrction pplince; QH, qud helix; RME, rpid mxillry expnsion. P vlues derived using the mixed model pproch. NS indictes not significnt. c Both sides were nested within ech tretment pplince. *P,.05. Computed tomogrphy is the most relile method for mesurement of ctul dentl root length. 11 However, it ws not possile to employ this method in this retrospective study. Previous studies hve routinely used peripicl rdiogrphs for mesurement of root length. 12,13 The present study employed occlusl rdiogrphs for mesurement of U1 root length ecuse there were only few peripicl rdiogrphs ville tht included U1 on oth the noncleft nd cleft sides. However, there were no significnt differences in originl root length or ME etween occlusl rdiogrphs cquired fter edgewise tretment nd peripicl rdiogrphs of U1 cquired during the sme period. Therefore, root length mesurement using occlusl rdiogrphs cquired fter edgewise tretment ws judged to e n cceptle method. An issue encountered during mesurement of U1 root length ws tht nteroposterior inclintions of U1 on the noncleft side t T1 were significntly different from those on the cleft side, lthough the corresponding mesurements t T2 on oth sides were comprle; this discrepncy ws rectified y pplying CFs clculted in ccordnce with crown heights t T1 nd T2. We elieve tht the methods used to evlute U1 root length on the noncleft nd cleft sides using occlusl rdiogrphs were cceptle. In the present study, cleft-djcent U1 roots were shorter thn non-cleft-djcent U1 roots t T1 (just efore SBG). Previous studies hve reported symmetric tooth formtion ptterns in ptients with unilterl CLP. 4,5 One of the etiologicl fctors for delyed tooth formtion in the mxillry cleft is the lck of spce for tooth formtion in the cleft re 14,15 nd growth ttenution due to indequte nutrition. 6 Upon frontl cephlometric nlysis, the U1-root VL distnce t T0 on the cleft side ws found to e lower thn tht on the noncleft side; this vrile ws sttisticlly correlted with root length t T1. During tretment, cre ws tken to void movement of roots into the cleft re efore SBG. Consequently, the root-pex position on the cleft side hd not chnged significntly etween T0 nd T1. This suggests tht cleft-djcent U1 with the root-pex position shifted to the noncleft side t T0 might hve hd short roots ecuse of lck of spce for development on the cleft side. At T2, the roots of cleft-djcent U1 were shorter thn those of U1 on the noncleft side, similr to the trend t T1. However, there ws no significnt difference in the chnge in root length from T1 to T2 etween the two sides. The cleft nd noncleft sides exhiited comprle root resorption in U1 etween T1 nd T2. Short dentl root length on the cleft side fter edgewise tretment (R2) might e correlted with root length efore SBG (R1). Root resorption etween T0 nd T1 could not e evluted ecuse the root pices t T0 hd not closed yet nd, consequently, it ws not possile to mesure the root length. However, most ptients with Tle 7. Results of Fixed-Effects Anlysis of Cephlometric Mesurements in Ptients Without MPA Fixed Effects Without MPA Period, T0 nd T1 Without MPA 3 Period, T0 nd T1 Mesurements F Vlue P Vlue F Vlue P Vlue F Vlue P Vlue Frontl cephlometric mesurements U1 xis ngle (8) 0.123 NS 2.427 NS 0.218 NS U1-root VL distnce (mm) 1.979 NS 0.286 NS 0.009 NS Lterl cephlometric mesurements U1 SN ngle (8) 4.656.039* 8.387.005** 0.301 NS U1 NA ngle (8) 3.918 NS 10.809.001** 0.173 NS U1-root NA distnce (mm) 4.441.046* 11.506.001** 0.586 NS U1 indictes centrl incisor; T0, t eruption of U1; T1, less thn 6 months prior to secondry one grfting; MPA, mxillry protrction pplince; VL, verticl line; SN, sell nsion; NA, nsion-point A. P vlues derived using the mixed model pproch. NS indictes not significnt. *P,.05; **P,.01.
ROOT LENGTH OF U1 IN PATIENTS WITH UCLP 861 Tle 8. Comprison of U1 Root Length Between Ptients nd Sides Treted With nd Without MPA Without MPA, N ¼ 18 With MPA, N ¼ 12 Without vs With MPA Adjusted Men P Vlue Adjusted Men P Vlue P Vlue All Teeth, Noncleft Cleft Noncleft vs All Teeth, Noncleft Cleft Noncleft vs All Noncleft Cleft Mesurement n ¼ 36 U1s Side Side Cleft Sides n ¼ 24 U1s Side Side Cleft Sides Teeth Side Side Root length t T1 (mm) 14.27 15.23 13.03.005** 12.75 13.31 12.47 NS.013*.035* NS U1 indictes centrl incisor; T1, less thn 6 months prior to secondry one grfting; MPA, mxillry protrction pplince. P vlues derived using generlized liner model with ech ptient eing considered s the covrite. Indictes significnce t P,.05 fter Bonferroni djustment for multiple comprisons. NS indictes not significnt. *P,.05; **P,.01. UCLP in the present study hd received tretment with orthodontic pplinces etween T0 nd T1. Root length in ptients treted with MPA ws significntly shorter thn tht in ptients treted without MPA, lthough there were no significnt differences in chnges oserved in frontl nd lterl cephlometric mesurements etween the two groups. Some studies hve reported tht externl picl root resorption is ssocited with the type of loding force used. 16 18 An orthodontic force of pproximtely 350 g per side ws pplied with the MPA, with prt of this force trnsmitted s intermittent force to the mxillry nterior teeth through orl pplinces such s lingul rch. Intermittent orthodontic force hs een shown in some studies to hve cused less root resorption thn continuous force of the sme mgnitude. 16,17 On the other hnd, in nother study, force exerted y J-hook hedger (force pplied continuously t night nd then completely relesed during the dy) cused greter root resorption thn the force pplied y tightening ligture tied from miniscrew to cuse intrusion. 18 The uthors of tht study suggested tht intermittent orthodontic forces such s those exerted y J-hook hedger might cuse jiggling, which is known risk fctor for externl picl root resorption. Recently, study in rts suggested tht jiggling might e risk fctor for root resorption nd tht it might induce root resorption through production of inflmmtory cytokines during orthodontic tooth movement. 19 Jiggling due to the MPA in this study might hve cused root resorption or prevented root formtion, resulting in short dentl roots efore SBG. Therefore, tretment with MPA should e strted t n erly stge, efore the eruption of mxillry permnent U1, to decrese the tretment period with MPA fter U1 eruption. In ddition, mxillry protrction with skeletl nchorge should e considered during the mixed dentition period. In ptients with UCLP, the root lengths of U1 were found to e comprtively short on the cleft side nd in teeth treted with MPA. The implictions of these findings should e reflected in the tretment pln for UCLP ptients. CONCLUSIONS Centrl incisor roots on the cleft side were shorter thn those on the noncleft side oth efore SBG nd fter edgewise tretment. At eruption nd efore SBG, cleft-djcent U1 exhiited greter shift of the root pex towrd the noncleft side thn did non-cleft-djcent U1. This prmeter ws correlted with root length. Root length just efore SBG in ptients who received tretment with MPA ws significntly shorter thn tht in ptients who received tretment without MPA. Thus, orthodontic force exerted y the MPA might result in short dentl roots. ACKNOWLEDGMENTS This study ws supported y grnts-in-id for scientific reserch (16K11791) from the Jpn Society for the Promotion of Science. We re grteful for the ssistnce of the clinicl stff of Kgoshim Hospitl. We thnk Dr Koji Atk nd Dr Suguru Kwzu, Kgoshim University, for their help with the sttisticl nlyses. REFERENCES 1. Al-Jml GA, Hzz AM, Rwshdeh MA. Crown-root rtio of permnent teeth in cleft lip nd plte ptients. Angle Orthod. 2010;80:1122 1128. 2. Brouwers HJ, Kuijpers-Jgtmn AM. Development of permnent tooth length in ptients with unilterl cleft lip nd plte. Am J Orthod Dentofcil Orthop. 1991;99:543 549. 3. Hzz AM, Rwshdeh MA, Al-Jml G, Al-Nimri KS. Dentl development in children with cleft lip nd plte: comprison etween unilterl nd ilterl clefts. Eur J Peditr Dent. 2009;10:90 94. 4. Rieiro LL, ds Neves LT, Cost B, Gomide MR. Dentl development of permnent lterl incisor in complete unilterl cleft lip nd plte. Cleft Plte Crniofc J. 2002;39:193 196. 5. Solis A, Figuero AA, Cohen M, Polley JW, Evns CA. Mxillry dentl development in complete unilterl lveolr clefts. Cleft Plte Crniofc J. 1998;35:320 328. 6. Rnt R. A review of tooth formtion in children with cleft lip/ plte. Am J Orthod Dentofcil Orthop. 1986;90:11 18. 7. Demirjin A, Goldstein H, Tnner JM. A new system of dentl ge ssessment. Hum Biol. 1973;45:211 227.
862 MAEDA-IINO, MARUTANI, FURUKAWA, NAKAGAWA, KWON, KIBE, TEZUKA, NAKAMURA, MIYAWAKI 8. Noll C. The development of the permnent teeth. J Dent Child. 1960;27:254 266. 9. Fontn ML, de Souz CM, Bernrdino JF, et l. Assocition nlysis of clinicl spects nd vitmin D receptor gene polymorphism with externl picl root resorption in orthodontic ptients. Am J Orthod Dentofcil Orthop. 2012;142:339 347. 10. Dhlerg G. Sttisticl Methods for Medicl nd Biologicl Students. London: Allen nd Unwin; 1940; 122 132. 11. Lund H, Gröndhl K, Gröndhl HG. Cone em computed tomogrphy for ssessment of root length nd mrginl one level during orthodontic tretment. Angle Orthod. 2010;80:466 473. 12. Becker A, Chushu S. Long-term follow-up of severely resored mxillry incisors fter resolution of n etiologiclly ssocited impcted cnine. Am J Orthod Dentofcil Orthop. 2005;127:650 654. 13. Levnder E, Mlmgren O. Long-term follow-up of mxillry incisors with severe picl root resorption. Eur J Orthod. 2000;22:85 92. 14. Eerens K, Vlietinck R, Heidüchel K, et l. Hypodonti nd tooth formtion in groups of children with cleft, silings without cleft, nd nonrelted controls. Cleft Plte Crniofc J. 2001;38:374 378. 15. Peterk M, Tvrdek M, Müllerová Z. Tooth eruption in ptients with cleft lip nd plte. Act Chir Plst. 1993;35:154 158. 16. Acr A, Cnyürek U, Kocg M, Erverdi N. Continuous vs. discontinuous force ppliction nd root resorption. Angle Orthod. 1999;69:159 163. 17. Bllrd DJ, Jones AS, Petocz P, Drendeliler MA. Physicl properties of root cementum: prt 11. Continuous vs intermittent controlled orthodontic forces on root resorption. A microcomputed-tomogrphy study. Am J Orthod Dentofcil Orthop. 2009;136:8.e1 e8. 18. Deguchi T, Murkmi T, Kurod S, Yuuchi T, Kmiok H, Tkno-Ymmoto T. Comprison of the intrusion effects on the mxillry incisors etween implnt nchorge nd J- hook hedger. Am J Orthod Dentofcil Orthop. 2008;133:654 660. 19. Hikid T, Ymguchi M, Shimizu M, Kikut J, Yoshino T, Ksi K. Comprisons of orthodontic root resorption under hevy nd jiggling reciprocting forces during experimentl tooth movement in rt model. Koren J Orthod. 2016:46:228 241.