Originl Article Dentoskeletl chnges following mini-implnt molr intrusion in nterior open bite ptients Tyler R. Hrt ; Richrd R. J. Cousley b ; Leonrd S. Fishmn c ; Ross H. Tllents d ABSTRACT Objective: To evlute skeletl nd dentl chnges fter intrusion of the mxillry molrs in subjects with nterior open bite. Mterils nd Methods: This retrospective cephlometric study evluted skeletl nd dentl chnges resulting from the use of mxillry orthodontic mini-implnts in 31 consecutively treted ptients. Rdiogrphs were tken t the strt nd end of mxillry molr intrusion to evlute the ssocited chnges. Sttisticl nlysis ws performed using one-smple t-test. Results: The men tretment observtion time ws 1.31 yers (SD 5 2.03). The mxillry first molrs (P 5 0.0026) nd second molrs (P 5 0.039) were intruded. However, the mndibulr first molrs (P 5 0.0004) nd second molrs (P 5 0.003) erupted in dolescent ptients. Both the mxillry nd mndibulr first molrs inclined distlly (P 5 0.025 nd P 5 0.044, respectively). The mndibulr plne ngle decresed (P 5 0.036), lower fcil height decresed (P 5 0.002), nd the occlusl plne ngle incresed (P 5 0.009). The overbite incresed (P,.0001). The ANB ngle decresed (P,.0001). Mndibulr dentl nd skeletl chnges were more pprent in dolescents, while dults tended towrd mxillry chnges. Conclusions: Verticl trction from orthodontic mini-implnts reduces the mxillry posterior dentolveolr height, thereby ssisting orthodontic closure of nterior open bite. However, simultneous eruption or extrusion of the mndibulr molrs should be controlled. Adolescent ptients tend to demonstrte more fvorble effects of mndibulr utorottion thn do dults. (Angle Orthod. 2015;85:941 948.) KEY WORDS: Mini-implnt; Anterior open bite; Molr intrusion INTRODUCTION Resident, Deprtment of Orthodontics nd Dentofcil Orthopedics, University of Rochester Estmn Institute for Orl Helth, Rochester, NY. b Consultnt Orthodontist, Peterborough nd Stmford Hospitls NHS Foundtion Trust, Cmbridgeshire, UK. c Clinicl Professor, Deprtment of Orthodontics nd Dentofcil Orthopedics, University of Rochester Estmn Institute for Orl Helth, Rochester, NY. d Orofcil Pin Progrm Director, Deprtment of Orthodontics nd Dentofcil Orthopedics, University of Rochester Estmn Institute for Orl Helth, Rochester, NY. Corresponding uthor: Dr Tyler R. Hrt, Resident, Deprtment of Orthodontics nd Dentofcil Orthopedics, University of Rochester Estmn Institute for Orl Helth, 625 Elmwood Ave, Rochester, NY 14620 (e-mil: trhrtdds@gmil.com) Accepted: November 2014. Submitted: September 2014. Published Online: December 22, 2014 G 2015 by The EH Angle Eduction nd Reserch Foundtion, Inc. Anterior open bite (AOB) is widely regrded s one of the more difficult mlocclusions to correct, especilly when ssocited with n incresed mxillomndibulr plne ngle (MMPA). Full correction often requires mxillry impction osteotomy to indirectly reduce the MMPA nd lower nterior fce height (LAFH). However, it is possible to successfully correct AOB with the djunctive use of temporry skeletl nchorge. 1 8 It hs been suggested tht pltl lveolr miniimplnts, coupled with customized rigid trnspltl rch provides optiml chnces for mini-implnt stbility nd molr intrusion, especilly in ptients with highrched pltes. 9,10 Severl studies hve investigted the totl effects of molr intrusion, but the results hve included dditionl mndibulr molr intrusion nd verticl mxillry nd mndibulr molr (occlusl) settling following both the intrusion phse nd tretment completion. 1,2,8,11 As result, the principl mxillry molr movements nd ny ssocited mndibulr chnges my be difficult to discern. In ddition, there hs not been n nlysis of ge effects (growing vs nongrowing cses) in the literture. Therefore, this study imed to nlyze the DOI: 10.2319/090514-625.1 941
942 HART, COUSLEY, FISHMAN, TALLENTS Figure 1. Elstomeric trction pplied from bilterl pltl (lveolr) mini-implnts to qud helix pplince. The mxillry second molrs hve been bonded s prt of bilterl sectionl fixed pplinces. dentl nd skeletl effects of mxillry molr intrusion using orthodontic mini-implnts t the end of the intrusion phse in both dolescent nd dult ptients. MATERIALS AND METHODS The Reserch Subjects Review Bord of the University of Rochester pproved this study. The records of 31 consecutively treted cses were collected retrospectively for the study. Ptient ges rnged from 11.6 yers to 55.5 yers (men, 20.7 yers). Twenty-one ptients were femle nd 10 were mle. Inclusion criteri were s follows: 1. Pretretment AOB 2. Mxillry molrs hd been intruded with miniimplnt trction s the principl tretment for AOB Exclusion criteri were s follows: 1. previous digit-sucking hbit within 2 yers prior to tretment, 2. bite-closing biomechnics such s multiloop edgewise rchwire nd/or intermxillry elstic trction used, 3. orthodontic spce closure in the mxillry rch during intrusion phse, 4. orthognthic or TMJ surgery during intrusion phse. Vritions in individul growth ptterns, fixed pplince prescription, nd Angle s molr clssifiction were not considered criteri for exclusion. Nor were type, commercil brnd, nd exct loctions of the mini-implnts considered within these criteri. Twenty-five of the ptients (group A) were treted by single orthodontist (R.C.) using stndrdized method tht gined nchorge from bilterl perimolr orthodontic mini-implnts. 9,10 Infinits mini-implnts (DB Orthodontics Ltd, UK; www.infinits-miniimplnt. Figure 2. Elstomeric trction pplied from single midpltl miniimplnt with dumbbell ttchment to trnspltl rch nd second molrs. com) with 1.5-mm dimeter nd 9-mm body length were used in ll cses. For 19 of the 25 ptients, single mini-implnt ws inserted in bilterl pltl lveolr sites between the first nd second molrs. For one dult ptient, they were inserted mesil to the first molr becuse of limited introrl ccess cused by trismus. Insertion sites mesil to the first molrs were utilized in the remining five dolescent ptients becuse of incomplete eruption of the second molrs. Only one of these five ptients hd the mini-implnts on the buccl side of the lveolus. Either modified trnspltl rch or qud helix expnsion pplince ws fitted on the mxillry first molrs during the intrusion phse in order to mintin or increse intermolr width (Figure 1). 9,10 The remining six ptients (group B) were treted by different orthodontist using method tht gined nchorge from single, midpltl mini-implnt. One Toms mini-implnt (Denturum GmbH & Co KG, Ispringen, Germny; www.denturum.de) with 1.5- mm dimeter nd 6-mm body length ws used in ll cses. The mini-implnt ws plced ner the midpltl rphe under locl nesthesi nd ws ttched to dumbbell-type trnspltl rch (Rocky Mountin Orthodontics, Denver, Colo; www.rmortho.com). Trction ws pplied with elstomeric chin from the dumbbell to lingul buttons on the mxillry first nd second molrs (Figure 2). Two lterl cephlometric rdiogrphs were collected for ech ptient. One rdiogrph ws tken before intrusion, nd one ws tken fter the end of the intrusion phse or full tretment. The lterl cephlometric rdiogrphs were clibrted to ctul size using Dolphin softwre nd trced mnully. They were then mesured independently three times by one investigtor to minimize ny errors. Twelve of the mesurements were derived from conventionl cephlometric nlyses. The other 18 were liner nd
MINI-IMPLANT MOLAR INTRUSION IN AOBS 943 Figure 3. Angulr cephlometric mesurements (degrees): 1 5 SNA, 2 5 SNB, 3 5 ANB, 4 5 FH-NA, 5 5 U1-FH, 6 5 L1-MP, 7 5 U1-L1, 8 5 MP-FH, 9 5 PP-SN, 10 5 OP-SN, 11 5 U6-FH, 12 5 L6- MP. Not shown: U7-FH, L7-MP. ngulr mesurements nd were relted to horizontl nd verticl reference lines (Figures 3, 4). The bsion horizontl plne, which is prllel to FH nd pltl plne were used to evlute verticl chnges. Decresing verticl vlues represent superior dentl movements. The reference line to ssess horizontl chnges ws constructed perpendiculr to Frnkfort horizontl (FH), intersecting the nterior curvture of the pterygomxillry fissure (PTM). This ws used becuse of the horizontl stbility of the PTM during growth. 12 An increse in horizontl vlues represents nterior movement. All sttisticl nlyses were conducted using Version 9.3 of the SAS System for Windows (SAS Institute Inc, Cry, NC). One smple sttisticl t-test ws used to evlute whether ny of the chnges were significntly different in terms of both the whole smple nd for two ge subgroups. Twenty-one of the ptients (group 1) were ge 18 yers or less before tretment ws initited, nd were compred with 10 ptients (Group 2) ge 19 yers or more. The estimted men differences nd ssocited 95% confidence intervls were clculted. Person correltion coefficients were clculted reltive to cephlometric chnges nd chronologicl ge. Intrrter relibility ws clculted from the three sets of cephlometric mesurements. Figure 4. Liner cephlometric mesurements (mm): 1 5 LFH (ANS-Me), 2 5 TFH (N-Me), 3 5 PLFH (ANS-MP), 4 5 PTFH (SES-MP), 5 5 U6- PTM, 6 5 L6-PTM, 7 5 OB, 8 5 OJ, 9 5 U6-PP, 10 5 U6-B, 11 5 L6-MP. Not shown: U7-PTM, L7-PTM, U7-PP, U7-B, L7-MP.
944 HART, COUSLEY, FISHMAN, TALLENTS Tble 1. Preintrusion nd Postintrusion Verticl Dentl Mesurements (mm) Preintrusion Post-intrusion Difference Men SD Men SD Men SD % Chnge Reltive to Initil Vlues Significnce OP-SN 22.9 5.3 24.2 5.5 1.3 0.13 6.6 ** U6-B 27.4 3.7 25.7 3.7 21.7 0.10 5.9 ** U6-PP 23.7 3.3 21.4 3.2 22.3 0.06 9.6 *** U7-B 24.4 3.8 23.1 4.1 21.3 0.12 4.8 * U7-PP 19.9 3.5 18.3 3.6 21.6 0.90 8 *** L6-MP 30.4 3.1 31.5 3.3 1.1 0.05 3.7 *** L7-MP 28.2 3.1 29.1 3.1 0.9 0.06 3.5 ** L6-MPA 82.1 6.7 79.5 5.4 22.6 0.05 2.9 ** L7-MPA 83.2 8 80.8 8.8 22.4 0.07 2.8 * OB 23.0 1.9 0.8 1.4 3.8 0.94 153 *** * P,.05; ** P,.01; *** P,.001. RESULTS Intrrter relibility ws 98.2% for ll mesurements. Verticl Dentl Chnges (Tble 1) The mxillry first nd second molrs were intruded in 90% (28/31) nd 74% (23/31) of the cses, respectively. The verge intrusion reltive to the pltl plne ws 2.3 mm for the first molrs nd 1.6 mm for the second molrs. The verticl molr chnges rnged from 25 mm to 1 mm for the first molrs nd 25 mm to 2.5 mm for the second molrs. The mndibulr first nd second molrs erupted in 77% (24/31) nd 65% (20/31) of the cses, respectively. The verge increse in distnce from the mndibulr plne ws 1.1 mm for the first molrs nd 0.9 mm for the second molrs. The chnges rnged from 22 mm to 6 mm for both the first nd second molrs. The verticl incisor reltionship, s represented by the overbite (OB), improved in 97% (30/31) of the cses. The verge mount of bite closure ws 3.9 mm, with rnge of 0 mm to 8.5 mm. The verticl incisor chnges re not reported seprtely since they were lso influenced by orthodontic lignment. Horizontl Dentl Chnges (Tble 2) The overjet (OJ) decresed in 65% (20/31) of the cses. The verge mount of OJ reduction ws 1.1 mm, with rnge of 23 mm to 6 mm. Chnges in OJ were not sttisticlly significnt. The mxillry nd mndibulr first molrs demonstrted more nteroposterior tipping thn did the second molrs. The mxillry first molrs tipped distlly in 74% (23/31) of the cses, by n verge of 2.6u, with rnge from 215u to 16u. The mndibulr first molrs tipped distlly in 58% (18/31) of the cses by n verge of 2.5u, with rnge from 26u to 11u. Skeletl Chnges (Tble 3) SNA decresed in 55% (17/31) of the cses by n verge of 0.7u, with rnge from 210.5u to 3u. SNB incresed in 58% (18/31) of the cses by n verge of 0.5u, with rnge from 4u to 26.5u. ANB decresed in 81% (25/31) of the cses by n verge of 1.2u, with rnge from 24u to 1u. Lnde s Angle (FH-NA) decresed in 68% (21/31) of the cses by n verge of 1.5u, with rnge from 211u to 3u. Both nterior nd posterior fcil height decresed. Lower nterior fcil height (ANS-Me) decresed in Tble 2. Preintrusion nd Postintrusion Horizontl Dentl Mesurements (mm) Preintrusion Postintrusion Difference Men SD Men SD Men SD % Chnge Reltive to Initil Vlues Significnce U6-PTM 18.0 4.7 18.2 4.8 0.2 0.20 2.8 NS U7-PTM 9.0 4.6 8.8 4.4 20.2 0.55 9.5 NS L6-PTM 19.6 3.9 20.4 4.3 0.8 0.15 4.8 NS L7-PTM 9.5 4.1 10.2 4.4 0.7 0.59 15.4 NS U6-FH 80.8 6.2 78.1 7.0 22.7 0.07 3.1 * U7-FH 72.1 7.3 74.3 9.2 2.2 0.10 3.2 NS OJ 4.0 2.8 2.9 2.5 21.1 1.40 12.8 NS U1-FH 112.7 8.5 110.8 8.4 21.9 0.06 1.6 NS L1-MPA 91.1 7.4 91.9 7.7 0.8 0.06 1.0 NS U1-L1 123.9 10.8 125.8 7.6 1.9 0.07 1.9 NS NS indictes not significnt; * P,.05; ** P,.01; *** P,.001.
MINI-IMPLANT MOLAR INTRUSION IN AOBS 945 Tble 3. Preintrusion nd Postintrusion Skeletl Mesurements (u) Preintrusion Postintrusion Difference Men SD Men SD Men SD % Chnge Reltive to Initil Vlues Significnce SNA 79.4 4.2 78.7 4.0 20.7 0.03 0.9 NS SNB 73.9 4.3 74.4 4.4 0.5 0.02 0.6 NS ANB 5.5 3.2 4.3 3.2 21.2 1.22 116.1 *** FH-NA 90.6 3.7 89.0 3.9 21.6 0.03 1.6 ** MP-FH 32.4 6.3 31.3 6.9 21.1 0.09 3.6 * PP-SN 8.2 3.3 7.6 3.4 20.6 0.24 6.7 NS LFH 73.3 7.4 71.8 7.1 21.5 0.03 2.0 ** TFH 120.2 16.6 121.5 8.1 1.3 0.29 4.4 NS PLFH 52.0 7.3 50.9 7.1 21.1 0.04 2.1 ** PTFH 95.4 7.2 94.6 7.0 20.8 0.02 0.8 * NS indictes not significnt; * P,.05; ** P,.01; *** P,.001. 71% (22/31) of the cses by n verge of 1.5 mm, with rnge from 27 mm to 6 mm. Totl fcil height (N-Me) decresed in 74% (23/31) of the cses by n verge of 1.4 mm, with rnge from 26 mm to 7 mm. Posterior lower fcil height (ANS-MP) decresed in 55% (17/31) of the cses by n verge of 1.2 mm, with rnge from 27 mm to 3 mm. Posterior totl fcil height (SES-MP) decresed in 55% (17/31) of the cses by n verge of 0.7 mm, with rnge from 26 mm to 4 mm. The mndibulr plne ngle (MP-FH) decresed in 61% (19/31) of the cses by n verge of 1.1u, with rnge from 27u to 5.5u. Inclintion of the occlusl plne (OP) incresed in 58% (18/31) of the cses by n verge of 1.3u, with rnge from 24u to 6u. Age-Relted Chnges (Tble 4) Chronologicl ge ws negtively correlted with OB (r 5 20.51, P 5 0.0047) nd SNB (r 5 20.36, P 5 0.046) chnges but positively correlted with OP-SN (r 5 0.38, P 5 0.0336) chnges. In group 1 (ptients # 18 yers of ge) the OB incresed in 100% (21/21) of the cses by n verge of 3.7 mm, with rnge from 0.5 mm to 8.5 mm. SNB incresed in 67% (14/21) of the cses by n verge of 0.9u, with rnge from 21u to 4u. ANB decresed in 81% (17/21) of the cses by n verge of 1.0u, with rnge from 23u to 0.5u. MP-FH decresed in 62% (13/ 21) of the cses by n verge of 1.5u, with rnge from 27u to 3u. TFH decresed in 67% (14/21) of the cses by n verge of 1.3 mm, with rnge from 26 mm to 1 mm. Mxillry first nd second molrs intruded in 86% (18/21) nd 71% (15/21) of the cses, respectively. The verge intrusion ws 2.1 mm for the first molrs nd 1.1 mm for the second molrs. Verticl molr chnges rnged from 25 mm to 1 mm nd 23 mmto 2.5 mm, respectively. The mndibulr first nd second molrs moved superiorly (erupted) in 86% (18/21) nd 62% (13/21) of the cses, respectively. The verge verticl movement ws 1.1 mm for both first nd second molrs. The rnges vried from 22 mm to 4 mm nd 21 mm to 6 mm, respectively. They lso tipped distlly in 67% (14/21) nd 62% (13/21) of the cses, respectively. The verge mount of tipping ws 3.4u nd 2.7u, nd the rnges vried from 26u to 11u nd 27u to 21u, respectively. Results for group 2 (ptients $ 19 yers of ge) showed tht the OB incresed in 90% (9/10) of the cses by n verge of 4.3 mm, with rnge from 0 mm to 8 mm. SNA decresed by 1.9u nd SNB ws reduced by 0.4u, cusing reduction of ANB in 80% (8/ 10) of the cses by n verge of 1.5u, with rnge from 24u to 1u. FH-NA decresed in 90% (9/10) of the cses by n verge of 2.7u, with rnge from 0u to 11u. OP inclintion incresed in 80% (8/10) of the cses by n verge of 2.4u, with rnge of 22u to 5u. Lower fcil height (LFH) ws reduced by 1.9 mm. Mxillry first nd second molrs intruded in 100% (10/ 10) nd 80% (8/10) of the cses, respectively. The verge intrusion ws 2.7 mm for the first molrs nd 2.6 mm for the second molrs. Verticl molr movements rnged from 21 mmto24.5 mm nd 26 mmto 2 mm, respectively. The mxillry first molrs tipped distlly in 80% (8/10) of the cses by n verge of 4.8u, with rnge from 23u to 13u. The mxillry incisors retroclined in 70% (7/10) of the cses by n verge of 5.7u, with rnge from 25u to 14u. DISCUSSION The retrospective smple studied here ws heterogeneous in terms of ptient ge, severity of AOB, incisor reltionship nd inclintions, nd tretment biomechnics. There re inherent weknesses in retrospective studies, nd these fctors probbly ccount for the wide rnges in cephlometric chnges (Tble 5). For exmple, while the men mxillry first molr intrusion ws 2.3 mm, the mximum chieved
946 HART, COUSLEY, FISHMAN, TALLENTS Tble 4. Tretment Chnges According to Age Subgroups: Group 1 (#18 y); Group 2 ($19) Totl Smple (31) Group 1 (21) Group 2 (10) Men SD Significnce Men SD Significnce Men SD Significnce SNA 20.7 0.03 NS b 20.2 0.01 NS 21.9 0.04 NS SNB 0.5 0.02 NS 0.9 0.02 ** 20.5 0.03 NS ANB 21.2 1.22 *** 21.0 0.96 *** 21.4 1.68 * FH-NA 21.6 0.03 ** 21.0 0.03 NS 22.8 0.03 * MP-FH 21.1 0.09 * 21.4 0.09 * 20.5 0.08 NS OP-SN 1.3 0.13 ** 0.8 0.12 NS 2.4 0.14 ** PP-SN 20.6 0.24 NS 20.7 0.23 NS 20.5 0.27 NS LFH 21.5 0.03 ** 21.3 0.02 *** 21.9 0.05 NS TFH 1.3 0.29 NS 2.7 0.35 NS 21.7 0.03 NS PLFH 21.1 0.04 ** 20.7 0.03 NS 22.0 0.05 NS PTFH 20.8 0.02 * 20.6 0.02 NS 21.0 0.01 NS U6-B 21.7 0.10 ** 21.3 0.10 NS 22.6 0.09 ** U6-PP 22.3 0.06 *** 22.1 0.06 *** 22.7 0.04 *** U7-B 21.3 0.12 * 20.6 0.12 NS 22.8 0.12 ** U7-PP 21.6 0.90 *** 21.1 0.08 ** 22.6 0.09 ** L6-MP 1.1 0.05 *** 1.0 0.04 *** 1.2 0.07 NS L7-MP 0.9 0.06 ** 1.1 0.06 ** 0.5 0.06 NS L6-MPA 22.6 0.05 ** 23.4 0.05 ** 20.8 0.05 NS L7-MPA 22.4 0.07 * 22.9 0.07 * 21.4 0.05 NS U6-PTM 0.2 0.20 NS 20.8 0.23 NS 20.8 0.08 NS U7-PTM 20.2 0.55 NS 0.1 0.65 NS 20.7 0.18 NS L6-PTM 0.8 0.15 NS 0.8 0.17 NS 0.8 0.13 NS L7-PTM 0.7 0.59 NS 0.7 0.71 NS 0.6 0.20 NS U6-FH 22.7 0.07 * 21.5 0.08 NS 25.0 0.06 ** U7-FH 2.2 0.10 NS 2.4 0.11 NS 1.7 0.07 NS OB 3.8 0.94 *** 3.7 0.73 *** 4.2 1.34 ** OJ 21.1 1.40 NS 21.0 1.74 NS 21.4 0.53 NS U1-FH 21.9 0.06 NS 20.1 0.06 NS 25.8 0.06 * L1-MPA 0.8 0.06 NS 0.6 0.06 NS 1.1 0.04 NS U1-L1 1.9 0.07 NS 0.6 0.06 NS 4.6 0.07 NS Liner cephlometric mesurements re in millimeters nd ngulr mesurements re in degrees. b NS indictes not significnt. * P,.05; ** P,.01; *** P,.001. ws 5 mm, to the extent tht some of these ptients hd verticl molr chnges such s expected only with orthognthic surgery. The men molr intrusion nd AOB correction demonstrted here is similr to those of other studies of dult subjects. 1,2,6,8,13 As in previous studies, 1,2,8,11 mndibulr plne ngultion, OB, nd mxillry first molr height (reltive to the pltl plne) ll demonstrted significnt chnges fter molr intrusion. These published studies lso demonstrted decreses in skeletl Clss II fetures, s represented by the ANB ngle, except tht of Deguchi et l. 2 Totl fcil height (TFH), LFH, nd mndibulr first molr height reductions were lso significnt in the current study, in greement with the study by Xun et l. 11 It seems tht combintion of chnges cuses the overll clinicl chnges of relevnce, especilly the increse in OB, reduction in the Clss II reltionship, nd long-fce fetures. In the current study, both the mxillry nd mndibulr molrs moved in n nterosuperior direction prllel to the PTM line. They lso demonstrted distl tipping. This my be explined by posterosuperior direction of trction on the mxillry first molr in mny of these ptients (where the mini-implnts were inserted distl to tht tooth). The sttisticlly insignificnt results of the chnges in OJ were initilly surprising compred with findings in other studies. 2,11 As the mndible moves nteriorly nd superiorly with closure of the AOB, it ppers logicl tht the OJ would decrese. However, such decrese ws demonstrted in only 65% of the cses. This lck of significnce is possibly due to considerble vritions (lrge stndrd devitions) in pretretment incisl inclintion nd whether the incisors were ligned during the observtion period. In prticulr, those ptients with full fixed pplinces for lignment of Clss II division 2 incisor reltionship would tend towrd reduction in OB t the sme time tht molr intrusion ws cusing n OB increse. Chronologicl ge ws not considertion in the exclusion criteri, nd our results suggest tht the reltive effects of molr intrusion my differ ccording to whether the ptient is growing. Buschng et l. (2011) 5 reported pilot study of nine dolescent
MINI-IMPLANT MOLAR INTRUSION IN AOBS 947 Tble 5. Tretment Chnges Reltive to Mini-Implnt Biomechnics Group A (25) Group B (6) Preintrusion Postintrusion Chnge SD Preintrusion Postintrusion Chnge SD SNA 79.2 78.7 20.5 0.02 80.2 78.3 21.9 0.05 SNB 73.8 74.4 0.6 0.02 74.4 74.0 20.4 0.04 ANB 5.4 4.3 21.1 1.06 5.8 4.3 21.5 1.86 FH-NA 90.4 89.4 21.0 0.03 91.1 87.7 23.4 0.04 MP-FH 32.7 31.0 21.7 0.08 31.2 32.5 1.3 0.08 OP-SN 23.0 24.7 1.7 0.14 21.0 22.2 1.2 0.13 PP-SN 8.4 7.6 20.8 0.26 7.8 7.9 0.1 0.13 LFH 74.0 72.5 21.5 0.02 69.8 68.6 21.2 0.06 TFH 124.0 122.2 21.8 0.32 119.0 118.4 20.6 0.05 PLFH 52.7 51.8 20.9 0.04 48.9 46.9 22.0 0.05 PTFH 96.5 95.6 20.9 0.02 90.7 90.4 20.3 0.02 U6-B 27.0 25.5 21.5 0.10 27.0 26.4 20.6 0.10 U6-PP 24.0 21.5 22.5 0.04 23.0 20.6 22.4 0.10 U7-B 24.5 22.9 21.6 0.12 23.7 23.9 0.2 0.14 U7-PP 20.0 18.2 21.8 0.08 19.0 18.3 20.7 0.11 L6-MP 31.0 31.6 0.6 0.04 29.0 30.8 1.8 0.09 L7-MP 28.0 29.5 1.5 0.06 28.0 27.5 20.5 0.07 L6-MPA 83.0 79.9 23.1 0.08 80.0 77.9 22.1 0.04 L7-MPA 83.0 81.0 22.0 0.08 84.0 78.9 25.1 0.10 U6-PTM 18.5 17.7 20.8 0.22 21.2 20.1 21.1 0.08 U7-PTM 8.4 8.5 0.1 0.59 11.0 10.0 21.0 0.24 L6-PTM 19.0 20.3 1.3 0.15 22.0 20.8 21.2 0.09 L7-PTM 8.9 10.1 1.2 0.63 11.9 10.6 21.3 0.25 U6-FH 79.0 76.9 22.1 0.08 86.0 83.6 22.4 0.05 U7-FH 71.0 73.9 2.9 0.10 76.0 75.7 20.3 0.11 OB 22.9 0.6 3.5 1.05 23.8 1.6 5.4 0.27 OJ 4.0 2.9 21.1 1.57 3.8 3.0 20.8 0.20 U1-FH 112.0 111.0 21.0 0.07 115.0 110.0 25.0 0.12 L1-MPA 90.0 91.4 1.4 0.06 93.0 93.8 0.8 0.04 U1-L1 125.0 126.3 1.3 0.07 121.0 124.1 3.1 0.03 Liner cephlometric mesurements re in millimeters nd ngulr mesurements re in degrees. ptients, but ours is the first pper to report both skeletl nd dentl chnges resulting from molr intrusion in dolescent ptients. Tretment t n erlier chronologicl ge, coincident with dolescent growth, showed sttisticlly significnt correltions with the chnges in OB, OP- SN, nd SNB. Adult ptients (group 2) demonstrted greter dentl chnges in terms of mxillry molr intrusion nd OB closure. This ws ssocited with greter steepening of the occlusl plne nd tendency to more reduction in SNA nd less nterior displcement of the mndible (SNB increse) thn in the dolescents (group 1) (Tble 4). In contrst, the dolescent group hd more fvorble mndibulr utorottion s demonstrted by men increse in SNB nd significnt reduction in MP-FH. Both ge groups hd men reduction in the LFH, but this ws t odds with n overll 2.7-mm men increse in TFH in dolescents. This my be interpreted s n indiction tht the intrusion-relted chnges in mndibulr position (reductions in LFH nd MP-FH) offset the underlying pttern of verticl fcil growth in growing individuls. The dult cses hd similr reduction in both LFH nd TFH. While the subgroup numbers re too smll for meningful sttisticl nlysis, our results lso indicte tht dult ptients demonstrted more mxillry second molr intrusion thn did the dolescents. This might be becuse most dult AOB occlusions re propped open on the second molr occlusl contcts while in dolescents these teeth would still be erupting. Both ge groups exhibited t lest some verticl mndibulr molr chnges, representing continued eruption or overeruption of the mndibulr molrs. However, these chnges were not significnt in the dult subgroup. Since uncontrolled eruption of the mndibulr molrs could mitigte the beneficil effects of the mxillry molr intrusion, the uthors recommend tht mndibulr molr positions be controlled from the strt of mxillry molr intrusion, especilly in dolescent ptients whose second molrs re still erupting. This could be chieved using either occlusl coverge of these molrs with vcuum-formed pplince (retiner), full fixed pplince enggement of ll erupted molr teeth, or nother relible form of mndibulr second molr nchorge. Future studies should include stndrdiztion of the clinicl intrusion technique including mini-implnt loction, mount nd vector of trction, trnspltl
948 HART, COUSLEY, FISHMAN, TALLENTS fixtures, nd mndibulr molr nchorge, prticulrly for dolescent subjects. Lrger ge subgroups in prospective study compred with controls would offer more meningful sttisticl nlysis of chnges in growing nd nongrowing ptients. CONCLUSIONS N Orthodontic mini-implnts provide dequte skeletl nchorge for mxillry molr intrusion in ptients with nterior open bites. N Therefore, this tretment modlity cn be considered resonble lterntive to orthognthic surgery for AOB correction in pproprite cses wherein the mlocclusion rther thn fcil esthetics is the primry issue. N While mxillry molr intrusion ids in the correction of AOB irrespective of ge, dolescent ptients tend to demonstrte more fvorble mndibulr utorottion chnges (Clss II correction). In contrst, more chnges occur in the occlusl plne ngle nd mxillry prmeters in dults. ACKNOWLEDGMENT Dr. Richrd Cousley hs finncil interest in the Infinits mini-implnt system, s sold by DB Orthodontics Ltd. No other reltionships, conditions, or circumstnces present conflict of interest for Dr. Cousley or ny of the other three uthors involved in the preprtion of this mnuscript. REFERENCES 1. Bek MS, Choi YJ, Yu HS, Lee KJ, Kwk J, Prk YC. Longterm stbility of nterior open-bite tretment by intrusion of mxillry posterior teeth. Am J Orthod Dentofcil Orthop. 2010;138:396.e1 e9; discussion, 396 398. 2. Deguchi T, Kurosk H, Oikw H, et l. Comprison of orthodontic tretment outcomes in dults with skeletl open bite between conventionl edgewise tretment nd implntnchored orthodontics. Am J Orthod Dentofcil Orthop. 2011;139(Suppl):S60 S68. 3. Krvitz ND, Kusnoto B, Tsy TP, Hohlt WF. The use of temporry nchorge devices for molr intrusion. J Am Dent Assoc. 2007;138:56 64. 4. Prk HS, Kwon TG, Kwon OW. Tretment of open bite with microscrew implnt nchorge. Am J Orthod Dentofcil Orthop. 2004;126:627 636. 5. Buschng PH, Crrillo R, Rossouw PE. Orthopedic correction of growing hyperdivergent, retrognthic ptients with miniscrew implnts. J Orl Mxillofc Surg. 2011;69: 754 762. 6. Akn S, Kocdereli I, Akts A, Tsr F. Effects of mxillry molr intrusion with zygomtic nchorge on the stomtognthic system in nterior open bite ptients. Eur J Orthod. 2013;35:93 102. 7. Kurod S, Ski Y, Tmmur N, Deguchi T, Tkno- Ymmoto T. Tretment of severe nterior open bite with skeletl nchorge in dults: comprison with orthognthic surgery outcomes. Am J Orthod Dentofcil Orthop. 2007; 132:599 605. 8. Lee H, Prk Y. Tretment nd posttretment chnges following intrusion of mxillry posterior teeth with miniscrew implnts for open bite correction. Koren J Orthod. 2008;38: 31 40. 9. Cousley RR. The Orthodontic Mini-Implnt Clinicl Hndbook. 1st ed. Wiley-Blckwell; 2013:184. 10. Cousley RR. A clinicl strtegy for mxillry molr intrusion using orthodontic mini-implnts nd customized pltl rch. J Orthod. 2010;37:202 208. 11. Xun C, Zeng X, Wng X. Microscrew nchorge in skeletl nterior open-bite tretment. Angle Orthod. 2007;77:47 56. 12. King EW. A roentgenogrphic study of phryngel growth 1. Angle Orthod. 1952;22:23 37. 13. Erverdi N, Keles A, Nnd R. The use of skeletl nchorge in open bite tretment: cephlometric evlution. Angle Orthod. 2004;74:381 390.