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American Journal of Orthodontics and Dentofacial Orthopedics Kinzinger et al 583 Volume 136, Number 4 Table III. Dental angular and linear measurements Cephalometric analysis n T1 mean T1 SD T2 M T2 SD D T1-T2 M D T1-T2 SD Significance Dental-angular U1/AN-PNS ( ) 10 107.93 4.80 108.50 4.94 –0.57 0.79 NS U1/SN ( ) 10 101.86 5.28 102.50 5.45 –0.64 0.75 NS U4/AN-PNS ( ) 10 91.86 6.01 90.71 6.11 1.15 2.98 NS U4/SN ( ) 10 85.86 7.61 85.07 7.37 0.79 2.23 NS U5/ANS-PNS ( ) 10 82.29 4.71 79.29 5.62 3.00 2.69 * U5/SN ( ) 10 76.50 5.37 73.29 5.26 3.21 2.86 * U6/ANS-PNS ( ) 10 75.36 3.82 72.57 4.04 2.79 2.51 * U6/SN ( ) 10 69.71 4.79 66.71 4.35 3.00 2.31 * Dental-linear U1-CEJ/PTV (mm) 10 52.54 2.94 52.90 2.98 –0.36 0.32 * U4-CEJ/PTV (mm) 10 38.47 3.37 39.19 3.78 –0.72 0.78 * U5-CEJ/PTV (mm) 10 31.21 3.11 29.34 3.00 1.87 0.74 † U6-CEJ/PTV (mm) 10 22.59 3.31 18.67 3.11 3.92 0.53 ‡ U1-CEJ/ANS-PNS (mm) 10 17.96 2.62 18.10 2.44 –0.14 0.29 NS U4-CEJ/ANS-PNS (mm) 10 15.79 1.53 15.93 1.55 –0.14 0.14 * U5-CEJ/ANS-PNS (mm) 10 14.59 2.06 15.01 1.97 –0.42 0.41 * U6-CEJ/ANS-PNS (mm) 10 13.16 1.78 13.00 1.65 0.16 0.26 NS *P \0.05; † P \0.01; ‡ P \0.001; NS, not significant. Table IV. Proportion of maxillary molar distalization in total movement in the sagittal plane Cephalometric analysis n D T1-T2 mean D T1-T2 SD Dental-linear (mm) U1-CEJ/PTV (mm) 10 –0.36 0.32 U4-CEJ/PTV (mm) 10 –0.72 0.78 U6-CEJ/PTV (mm) 10 3.92 0.53 Total sagittal movement 1-6* 10 4.28 0.51 Total sagittal movement 4-6 † 10 4.64 1.06 Calculation of ratio (%) Proportion of molar 10 91.71 7.32 sagittal movement 1-6 ‡ distalization in total Proportion of molar distalization in total sagittal movement 4-6 § 10 86.56 13.21 *Total movement in the sagittal plane 1-6 5 [U1-CEJ/PTV] 1 [U6- CEJ/PTV]; † Total movement in the sagittal plane 4-6 5 [U4-CEJ/ PTV] 1 [U6-CEJ/PTV]; ‡ Calculation: proportion of molar distalization in total sagittal movement 1-6 5 100 3 (U6-CEJ/PTV)/([U1- CEJ/PTV] 1 [U6-CEJ/PTV]); § Calculation: proportion of molar distalization in total sagittal movement 4-6 5 100 3 (U6-CEJ/PTV)/ ([U4-CEJ/PTV] 1 [U6-CEJ/PTV]). should be derotated with an appropriate appliance, such as a transpalatal bar or a bi-helix. We found, during lateral cephalograph analysis, unlike the results of the in-vitro analysis, that the permanent first molars experienced slight dental crown tipping in the sagittal plane rather than root uprighting. 4 The cause of this might be that the patients’ palatal vaults were not deep enough to enable placement of the loaded coil systems at the level of the center of resistance of the molars. Also, the location of the center of resistance can be determined only by approximation. Moreover, the respective development stages of the second molars might influence the extent of distal tipping of the first molars. In most patients in this study, the second molars were germinating or erupting. In a clinical study with pendulum appliances, Kinzinger et al 8 showed that the extent of distal tipping is relatively greater when the second molars are only germinating. This phenomenon can be explained as follows: a germinating second molar has the same effect as a lever pivot point on the permanent first molar to be distalized; the first molar, when reacting to distalization, tips over the second molar germ. <strong>As</strong> its root is developing and the permanent second molar is erupting, the point of contact between the 2 molars gradually moves coronally. The tendency for the first molar to tip thereby decreases. Conventionally, the anchorage setup of exclusively intraorally anchored appliances for noncompliance molar distalization combines an acrylic button on the palatal mucosa with using the periodontium of anchorage teeth. The disadvantages of this kind of anchorage include, in particular, restrictions to hygiene 5 and contraindications based on certain dentition stages and local situations. 7 Moreover, it must be discussed how far the anchorage effect of an anteriorly placed Nance button potentially relies only on hydrodynamic interactions due to the resilient mucosa. Thereby it would be a disqualifying design for stationary anchorage designs, and hence must not be overestimated in terms of anchorage quality. 5
584 Kinzinger et al American Journal of Orthodontics and Dentofacial Orthopedics October 2009 Table V. Studies using different conventionally intraorally anchored appliances for maxillary molar distalization Author/reference Distalization appliance Treatment Soft-tissue subjects (n) support* Dental anchorage † Share of molar distalization in total movement (%) Angelieri et al 31 Hilgers pendulum with uprighting activation 22 NP 2 B PM1 35.7 PM1, 45.4 I 2 OW PM2 Bolla et al 32 Distal jet 20 NP 2 B PM1 71.1 PM1 Bondemark and Kurol 33 Magnets 10/10 NP 2 B PM2 70 I Bondemark et al 34 Magnets/supercoils 18/18 NP 2 B PM2 53.7 I/62.7 I Bondemark and Kurol 35 Magnets/supercoils 18/18 NP 2 B PM2 55 I/59 I Bondemark 36 Magnets/NiTi coils 21/21 NP 2 B PM2 59.1 PM1, 57.8 I/67.6 PM1, 61.9 I Brickman et al 37 Jones jig 72 NP 2 B PM2 55.7 PM1 Bussick and McNamara 38 Hilgers pendulum 101 NP 4 OW 76.0 PM1 Byloff and Darendeliler 39 Hilgers pendulum 13 NP 4 OW 70.9 PM1 Byloff et al 40 Hilgers pendulum with 20 NP 4 OW 64.2 PM1 uprighting activation Chaques-<strong>As</strong>ensi and Kalra 41 Hilgers pendulum 26 NP 2 B PM1 70.6 PM1; 71.8 I Chiu et al 42 Distal jet/Hilgers pendulum 32/32 NP 2 B PM2/4 OW 51.8 PM1/81.3 PM Fortini et al 43 FCA 17 NP 2 B PM2 70.2 PM1; 76.9 I Fuziy et al 44 Hilgers pendulum 31 NP 2 B PM1 63.5 PM1 2 OW PM2 Gosh and Nanda 45 Hilgers pendulum 41 NP 4 OW 56.9 PM1 Gulati et al 46 Jones jig 10 NP 4 B PM1 and PM2 55.0 PM1 Haydar and Üner 47 Jones jig 10 NP 2 B PM2 45.0 PM1 Joseph and Butchart 48 Hilgers pendulum 7 NP 4 OW 57.9 I Kinzinger et al 50 Pendulum K 50 NP 4 OW 72.5 I Kinzinger et al 8 Pendulum K 36 NP 4 OW 70.2 I Kinzinger et al 50 Pendulum K 30 NP 4 OW 76.3 PM1; 74.2 I Kinzinger et al 51 Pendulum K 10 NP 4 OW 73.5 I Mavropoulos et al 52 Jones jig 66 NP 2 B PM2 47.8 PM2; 51.3 I Ngantung et al 53 Distal jet 33 NP 2 B PM2 44.9 PM2 Nishii et al 54 Distal jet 15 NP 2 B PM2 63.1 PM1; 61.5 I Papadopoulos et al 55 Modified jig 14 NP 2 B PM2 35 PM1, 37.8 I NiTi, Nickel-titanium; FCA, first-class appliance. * Intraoral anchorage designs: NP, Nance pad; B, premolar bands anchored to the Nance pad with connecting wires; OW, occlusal wire rests anchored to the Nance pad; PM1, first premolars; PM2, second premolars. † With specific reference: PM1, first premolar; PM2, second premolar; I, central incisor. Alternative anchorage components for molar distalization appliances include titanium miniscrews of small diameter and orthodontic implants of short length. In clinical application, short endosseous titanium implants provide quality stationary anchorage. 9-13 So-called miniscrews, placed at a location paramedian to the palatal suture in the patients in this study, are less costly and, compared with short implants, can be placeed and removed with minimal invasion. Most clinical and experimental studies as well as case reports on anchorage with miniscrews deal with primary stability, rate of loss, and patient comfort of these implants. 14-27 Only a few studies provide information on position stability of these anchorage components during orthodontic treatment. Liou et al 28 and Kinzinger et al 29 examined the anchorage quality of miniscrews subjected to orthodontic forces and concluded that, although they allowed stable anchorage, they did not fully maintain their positions under continuous loading. According to Park et al, 30 some mobility in orthodontic screw implants does not necessarily mean that the outcome is compromised. Rather, even minimally mobile miniscrews can provide sufficient anchorage quality. Our results show that the described miniscrew-supported periodontal anchorage does not allow anchorage of stationary quality. Nevertheless, it offers essential advantages compared with conventional anchorage designs; by limiting the number of occlusal rests to 2, treatment is possible even with fewer teeth, with lower anchorage quality in the supporting zone. Spontaneous distal drifting of the second premolars, which were not part of the anchorage setup, reduced the length of the subsequent treatment phase. In this study, the second premolars drifted distally after the molars almost bodily
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