Distalization of the molars has become a popular

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1 SYSTEMATIC REVIEW Are orthodontic distalizers reinforced with the temporary skeletal anchorage devices effective? Piotr Fudalej a and Joanna Antoszewska b Nijmegen, The Netherlands, and Wroclaw, Poland Introduction: Our objective was to perform a systematic review of studies pertaining to the distalization of teeth with appliances reinforced with temporary skeletal anchorage devices. Methods: PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Knowledge, Ovid, and Scopus were searched until the second week of August 2010 to identify all articles reporting on the use of orthodontic implants or miniplates in distalization of teeth. The quality of the relevant studies was ranked on an 11-point scale, from low to high quality. Results: Twelve relevant articles were identified. The distal movement of the maxillary molars was from 3.3 to 6.4 mm; the concomitant molar distal tipping was from 0.80 to The maxillary incisors remained stable during molar distalization. The assessment of study quality showed that 8 studies were of low and 4 of medium quality. Conclusions: Molar distalizers reinforced with the temporary skeletal anchorage devices seem to effectively move molars distally without unwanted mesial incisor tipping. Because of the lack of high-quality studies, however, the findings of this study should be interpreted with caution. (Am J Orthod Dentofacial Orthop 2011;139:722-9) Distalization of the molars has become a popular nonextraction treatment alternative in some patients with Class II malocclusions. There are numerous methods to move teeth distally; some techniques require a patient s active compliance, whereas others do not. Because patients cooperation during orthodontic treatment is frequently problematic, the appliances that eliminate the need for compliance are usually deemed superior to those demanding cooperation. Although popular noncompliance appliances, such as the pendulum 1 and the distal jet, 2 are effective in distalizing molars, the distalization process is associated with the concomitant loss of anterior anchorage. Sfondrini et al 3 critically evaluated various appliances used for molar distalization and found that most noncompliant appliances were associated with mesial movement or tipping of the incisors, a Assistant professor, Department of Orthodontics and Oral Biology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands; Assistant professor, Department of Orthodontics, Palacky University, Olomouc, Czech Republic. b Assisstant professor, Department of Dentofacial Orthopedics and Orthodontics, Wroclaw Medical University, Wroclaw, Poland. The authors report no commercial, proprietary, or commercial interest in the products of companies described in this article. Reprint requests to: Piotr Fudalej, Department of Orthodontics and Craniofacial Biology, Radboud University Nijmegen Medical Centre, 309 Dentistry, PO Box 9101, 6500 HB Nijmegen, The Netherlands; , P.Fudalej@dent.umcn.nl. Submitted, August 2010; revised, December 2010; accepted, January /$36.00 Copyright Ó 2011 by the American Association of Orthodontists. doi: /j.ajodo synonymous with loss of anchorage. Similar conclusions were made by Antonarakis and Kiliaridis, 4 who systematically reviewed the effects of noncompliance tooth-borne distalizers. They found that distalization of molars is related to unavoidable loss of anchorage, which was observed as premolar mesial movement and incisor mesial crown and tipping movements. To reinforce anchorage and reduce unwanted movement of the incisors and premolars, a temporary skeletal anchorage device (TSAD) can be used. The TSAD is defined as a device that is temporarily fixed in bone for reinforcement of orthodontic anchorage. 5 Because a TSAD is stable, it provides absolute anchorage. To date, many distalization appliance designs incorporating TSADs have been developed. They range from the skeletal anchorage system (SAS) with miniplates placed in the zygomatic region in the maxilla 6 or retromolar region of the mandible 7 to appliances supported by a single orthodontic implant in the anterior palate. 8 Although the current studies suggest that these appliances might be effective in moving molars distally, an in-depth analysis is needed to investigate also other aspects of distalization, such as a rate and duration of molar movement. Therefore, the objectives of this systematic review were to evaluate the effectiveness of the distalization of molars with distalizers supported with TSADs and to compare the effectiveness of TSADreinforced distalizers with tooth-borne noncompliance distalization appliances. 722

2 Fudalej and Antoszewska 723 MATERIAL AND METHODS PubMed, Embase, Cochrane Central Register of Controlled Trials, Web of Knowledge, Ovid, and Scopus were searched until the second week of August of 2010 to identify all articles reporting on the use of TSADs in distalization of molars. The search strategy used in this review is shown in Table I. Based on the data from titles and abstracts of the retrieved studies, both authors independently selected articles that met the following inclusion criteria. 1. Studies on human subjects, published in English. 2. Studies that included clear descriptions of the distalization appliance and the technique. 3. Prospective or retrospective original studies (case reports and review and summary articles were excluded). 4. Studies with minimum 10 subjects in the sample. The reference lists of these articles were perused, and references related to the articles were followed up. If there was disagreement between the authors, inclusion of the study was confirmed by mutual agreement. From the identified articles, the authors independently extracted data referring to year of publication, type of study, sample size, site of implant or miniplate placement, type of distalizing appliance, magnitude of force exerted on the teeth, duration of treatment, age at the start of treatment, presence of second molars, calculation of the method error, amounts of molar retraction and tipping, and changes of the position of the central incisors (Table II). According to the Centre for Reviews and Dissemination, evaluation of methodologic quality gives an indication of the strength of evidence provided by the study because flaws in the design or conduct of a study can result in bias. 9 However, no single approach for assessing methodologic soundness is appropriate to all systematic reviews. The best approach should be determined by contextual, pragmatic, and methodologic considerations. Therefore, quality assessment performed independently by the authors comprised evaluation of the selection process (including information about whether the sample consisted of consecutively treated patients), sample size estimation, adequacy of outcome measures, adequacy of method error estimation, and adequacy of statistical analysis (Table III). If there was disagreement between the authors, consensus was reached after discussion. The quality of the studies was ranked on an 11-point scale and assessed accordingly: high, with a total score of 11 points; medium high, with a total score 9 or 10 points; medium, with a total score 7 or 8 points; and low, with a total score below 7 points. Table I. Search strategy 1. orthodontic* 2. micro-implant* OR microimplant* OR micro implant* 3. mini-implant* OR mini implant* 4. orthodontic implant* 5. mini-plate* OR mini plate* 6. palatal implant* OR midpalatal implant* 7. buccal implant* 8. miniscrew* OR mini-screw* OR mini screw* 9. microscrew* OR micro-screw* OR micro screw* OR 3 OR 4 OR 5 OR 6 OR 7 OR 8 OR AND 10 Statistical analysis A meta-analysis of the results of the studies that used comparable techniques of distalization was planned with the aid of the RevMan software (version 5.0, The Nordic Cochrane Centre, Copenhagen, Denmark). 10 Heterogeneity of the studies was assessed first by calculating the I 2 index. 11 According to the recommendation of the Cochrane Collaboration, if heterogeneity is high (I 2,.75%), a meta-analysis might produce misleading results, and omitting it from a systematic review should be considered. 10 RESULTS The search of PubMed yielded 357 publications; Embase, 272; Cochrane Central, 45; ISI Web of Knowledge, 802; Ovid, 919; and the Scopus, 518; there was overlap among the databases. Application of the inclusion and exclusion criteria and follow-up on the referred studies allowed identification of 12 relevant publications (Fig, Table II). Heterogenity of the results of the investigation with a similar technique of distalization was high (.85%). 8,12-18 A meta-analysis was not performed for this reason. In total, 223 subjects (78 male, 145 female) were examined. However, 2 studies most likely evaluated the outcome in the same samples. 8,12 The mean age at the start of molar distalization in the evaluated samples ranged from 13 years 13 to 27.3 years. 19 Overall, in 6 studies, the samples comprised teenagers; in 3 studies, adults; and in 1 study, the sample included teenagers and adults. 20 Onçag etal 16 did not report on the mean age at the start of treatment, and Gelg or et al 8 gave only the age range at the start of distalization. In 6 studies (153 subjects), an area adjacent to the median suture in the anterior region of the hard palate was chosen as the site for placement of the orthodontic implant; the anchorage devices were also placed in the infrazygomatic crest region (2 studies, 42 subjects) and the anterior margin of the mandibular ramus (1 study, American Journal of Orthodontics and Dentofacial Orthopedics June 2011 Vol 139 Issue 6

3 724 Fudalej and Antoszewska Table II. Characteristics of the samples, distalization techniques, and outcomes in the included studies. Type of study; consecutive patients (Y, N); control group (Y, N) Study Cornelis and De Clerck, Y; N Escobar Y; N Gelg or Prospective; NR; N Gelg or * Gelg or y Kinzinger Kircelli N; Y N; Y N; N Prospective; NR; N Oberti Prospective; NR; N Oncag Y; Y Park Y; N Polat-Ozsoy N; Y Sample size 17 (15 female, 2 male) 15 (6 girls, 9 boys) 25 (18 girls, 7 boys) 20 (8 girls, 12 boys) 20 (11 girls, 9 boys) 10 (8 girls, 2 boys) 10 (9 girls, 1 boy) 16 (4 girls, 12 boys) 15 (9 girls, 6 boys) 13 (8 girls, 5 boys) 22 (15 girls, 7 boys) Age at start of treatment in years (SD) Site of placement of the TSAD TSAD diameter, length Osseointegration (Y or N) Distalization appliance 27.3 (NR) Infrazygomatic crest Miniplate N Elastics attached to maxillary fixed appliance 13 (2.1) Anterior palate 2 implants: 2.0 mm, 11 mm 13.8 (NR) Anterior palate 1.8 mm, 14 mm NR (NR); range, NR (NR); range, Anterior palate Anterior palate 1.8 mm, 14 mm 1.8 mm, 14 mm 12.1 (NR) Anterior palate 1.6 mm, 8-9 mm 13.5 (1.8) Anterior palate 2.0 mm, 8mm 14.3 (NR) Anterior palate 2 implants: 2.0 mm, 11 mm NR (NR) Anterior palate 3.8 mm; 9mm 17.9 (5.7) 9 patients: Mn implants distal to second molars or in retromolar area; 2 patients: Mx implants in buccal alveolar bone between second premolars and first molars; 2 patients: both Mn and Mx implants Magnitude of force 150 g N Modified pendulum appliance 250 g N Transpalatal bar 250 g between premolars supported by implant and nickel-titanium open coil between premolar and molar on the buccal side N Transpalatal bar 250 g between premolars supported by implant and nickel-titanium open coil between premolar and molar on the buccal side N Appliance 250 g consisting of acrylic palatal button attached to implant, premolar rests, and nickeltitanium open coils on the lingual side N Distal jet 200 g N N Y Pendulum appliance Dual force distalizer Pendulum springs made of beta nickel-titanium wire various NR Nickel-titanium coils and elastomeric thread NR g 300 g 200 g 13.6 (2.0) Anterior palate 2.0 mm, 8 mm N Pendulum appliance 230 g June 2011 Vol 139 Issue 6 American Journal of Orthodontics and Dentofacial Orthopedics

4 Fudalej and Antoszewska 725 Table II. Continued Study Type of study; consecutive patients (Y, N); control group (Y, N) Sugawara N; N Sugawara et al., N; N Sample size 15 (12 female, 3 male) 25 (22 female, 3 male) Age at start of treatment in years (SD) Site of placement of the TSAD 26.9 (NR) Anterior margin of mandibular ramus 23.9 (NR) Infrazygomatic crest TSAD diameter, length Titanium plates Titanium plates Osseointegration (Y or N) Distalization appliance Magnitude of force N SAS NR N SAS NR Treatment duration in months (SD) Presence of second molars Method error Study Cornelis and De Clerck, Escobar 7.8 (NR) NR Intraclass correlation coefficient Amount of molar distal movement/ tipping (mm/ ) Monthly rate of molar movement (mm) Amount of central incisor mesial movement/ tipping (mm/ ); negative value for distal movement/ tipping Success rate 7.0 (2.0) 100% N 3.3/ /NR 100% 6.0/ / 2.5 Unclear 4.6 (NR) 88% Dahlberg s Gelg or 3.9/ /1.0 NR method Gelg or 4.6 (NR) 90% Dahlberg s 4.0/ / 1.1 NR * method 1 correlational analysis Gelg or 5.4 (NR) 85% Dahlberg s 3.9/ / 0.1 NR y method 1 correlational analysis Kinzinger 6.7 (NR) 20% fully N 3.8/ / 0.6 NR erupted, 25% erupting Kircelli (1.8) NR Spearman correlation coefficient between repeated measurements 6.4/ / 0.6 NR Oberti (NR) Unerupted or just recently erupted Oncag Intraclass correlation coefficient 5.9/ / 0.8 NR Left side, 2/ (NR) NR ANOVA test 4.0/ Right side, 0.1/1.0 NR Park (5.7) Mostly Paired t test Mn first * Mn central 90% present molars, 2.9/5 incisors, NR Polat-Ozsoy (1.7) 13.6% Spearman correlation coefficient between repeated measurements 4.8/ / 1.7 Unclear Sugawara (NR) 100% Unclear 3.5/NR; tipping ratio, 46.3% Sugawara 19 (NR) 100% Unclear 3.8 mm crown, mm root Y, yes; N, no; NR, not reported; Mn, mandibular; Mx, maxillary. *Group 1 evaluated by Gelg or et al 8 ; y group 2 evaluated by Gelg or et al NR NR 0.2 NR NR American Journal of Orthodontics and Dentofacial Orthopedics June 2011 Vol 139 Issue 6

5 726 Fudalej and Antoszewska Table III. Assessment of the study quality A. Description of B. C. D. E. Choice of F. Adequacy of G. Adequacy of Judged selection Prospective or Consecutive Sample outcome method error statistical Quality quality Study process retrospective cases size measure analysis analysis score standard Points 0, 1, or 2 0 or 2 0 or 1 0 or 1 0, 1, or 2 0, 1, or 2 0 or 1 Cornelis and Low De Clerck, Escobar Low Gelg or Medium Gelg or Low Kinzinger Low Kircelli Medium Oberti Medium Oncag Low Park Medium Polat-Ozsoy Low Sugawara Low Sugawara Low Description of quality score assignment: A: 0, if inadequate description; 1, if some details of sample selection missing; 2, if in-depth description of sample selection. B: 0, if retrospective; 2, if prospective. C: 0, if sample comprised unconsecutive patients or no information regarding this was included; 1, if sample comprised consecutive patients. D: 0, if \20 subjects; 1, if $20 subjects. E: 0, if inadequate outcome measure; 1, if partially adequate outcome measure; 2, if adequate outcome measure. F: 0, if method error not evaluated; 1, if partially adequate method error analysis; 2, if adequate method error. G: 0, if inadequate; 1, if adequate. 15 subjects). The pendulum appliance was used most frequently to distalize the molars. In subjects in whom miniplates were placed, elastomeric power chains attached to the fixed orthodontic appliance were used. The duration of treatment ranged from 4.6 to 28.9 months. However, in most studies, distalization of molars did not last more than 8 months. In the studies that reported treatment time exceeding 8 months, enmasse retraction of the whole dentition was carried out. The mean distal movement (Table II) of the maxillary molars ranged from 3.5 to 6.4 mm. Concomitant distal tipping ranged from 0.80 to (Table II). The position of the central incisors was largely stable; only Cornelis and De Clerck 19 found a statistically significant retraction by 1.4 mm (P\0.05), and Oberti et al 17 detected 0.5 mm of retraction of the central incisors (P \0.05). The assessment of the quality showed that 8 studies were of low quality, and 4 studies demonstrated medium quality. In general, the methodologic soundness of the studies was compromised by retrospective designs without inclusion of consecutively treated patients, inadequate sample sizes, and lack of analysis of method errors. DISCUSSION In this study, we aimed to review articles that had evaluated the effectiveness of orthodontic distalizers reinforced with TSADs. A systematic review seemed the most appropriate, because its methodology makes June 2011 Vol 139 Issue 6 American Journal of Orthodontics and Dentofacial Orthopedics

6 Fudalej and Antoszewska 727 QUOROM Flow Diagram Potentially relevant articles after search of the electronic databases (n = 1215) Manual search; relevant articles (n = 3) Articles retrieved for more detailed evaluation (n = 1130) Articles retrieved for more detailed evaluation (n = 888) Included articles (n = 9) Excluded articles, non- English (n= 85) Excluded articles, nonhuman studies, reviews (n= 242) Excluded articles, not relevant to the subject of the present study, case reports, description of technique, < 10 subjects in sample (n = 879) Total number of included articles (n = 12) Fig. Flowchart illustrating the selection of relevant articles. possible identification, appraisal, and synthesis of most available evidence. Depending on the quality of the included studies, a systematic review can provide various levels of scientific evidence ranging from the highest, if only randomized clinical trials are included, to the lowest, if only retrospective investigations are reviewed. 21 In the latter case, a systematic review summarizes what is already known, indicates the weaknesses of the studies, and highlights the areas requiring further research. This systematic review included only nonrandomized prospective and retrospective studies. The methodologies of these investigations were generally of low and medium quality (Table III). Consequentially, our findings should be interpreted with caution, and conclusions that can be drawn from them are necessarily tentative. These results suggest that the TSADs used as anchors supporting distalizing appliances reduce the unwanted side effects of tooth-borne appliances. Antonarakis and Kiliaridis 4 found in their systematic review that tooth-borne distalizers could move maxillary molars distally on average 2.9 mm; however, the associated undesirable incisor mesial movement was 1.8 mm. Our findings indicate that reinforcement of anchorage with orthodontic implants or miniplates increased the amount of molar distalization. The distal movements of the maxillary molars in the studies with comparable distalization techniques were from 3.9 to 6.4 mm. 8,12-18 At the same time, the maxillary incisors remained stable. This implies better outcomes produced by TSADreinforced distalization devices than by tooth-borne appliances. A distal movement of the molars is the effect of bodily tooth movement and tipping, which is usually not desired clinically. The findings of the studies that used similar techniques of distalization showed that the distalization of molars was associated with 3.0 to of distal tipping. 8,12-18 Only Gelg or et al 8 found minimal molar tipping (0.80 ) in 1 of their 2 study groups. This was also found by Antonarakis and Kiliaridis, 4 who reported 5.40 of molar distal tipping after the use of tooth-borne distalizing appliances. The greater molar distal tipping observed in patients with the TSADs might have resulted from excessive pressure exerted on the molars by the distalizers. Assuming that the force values generated by the tooth-borne and TSADssupported appliances were comparable, less pressure was applied to the molars in subjects with the toothborne appliances than in those with the TSADs because, American Journal of Orthodontics and Dentofacial Orthopedics June 2011 Vol 139 Issue 6

7 728 Fudalej and Antoszewska in the former group, the force was dissipated also in the anterior direction, causing mesial movement or tipping of the maxillary incisors. In subjects with TSADs, this was not possible because of the stability of the implants. Nonintegrated TSADs placed in the paramedian region of the anterior palate were used to reinforce distalization appliances in most studies in this review. In comparison with osseointegrated TSADs, nonintegrated TSADs offer several advantages to the clinician, such as immediate loading, simpler surgery, lower cost, and less discomfort to the patient. Our results suggest that nonintegrated TSADs were successful in anchorage reinforcement during distalization. However, few data regarding failure rates limit the strength of this conclusion. Only the authors of 2 studies showed the proportions of successfully and unsuccessfully treated patients. 13,18 Escobar et al 13 reported that the treatment of 2 patients was unsuccessful (success rate, 87%) because of tissue inflammation and failure of the screw. They, however, used a modified pendulum appliance attached to the palate with 2 screws. It is unclear whether all TSADs in the remaining subjects were stable. Polat- Ozsoy et al 18 reported the lack of stability of 4 TSADs in 3 subjects. Because most patients wore distalization appliances supported by 2 TSADs, instability of the TSADs was noticed during accidental damage of the distalizing spring or at the appliance removal. Although the clinical success rate in the study by Polat-Ozsoy et al was 100%, it is difficult to generalize these data because other investigators used distalization appliances supported by a single palatal implant. It is possible, then, that loosening of the implant in such cases could lead to clinical failure. Therefore, conclusions regarding the effectiveness of the nonintegrated TSADs can be made only after more data concerning rates of successful and unsuccessful outcomes are obtained. The rates of molar distalization achieved with different devices, calculated as millimeters of molar distal movement per month, can be an important factor for a clinician during selection of the distalization appliance. The results of this review showed that the mean distal movement of the maxillary molars was 0.7 mm (SD, 0.3 mm) per month (range, mm). The slowest rate was observed for the SAS system described by Sugawara et al 6 ; a similar technique was used by Cornelis and De Clerck, 19 and the fastest was when the dual-force distalizer was used. 17 The slowest distalization rate found for the SAS was most likely because the whole maxillary dentition was distalized simultaneously, since the distal force was applied to the fixed appliances worn by the patient. Conversely, the fastest rate of distalization was achieved when the force was applied to the molars only. The use of the dual-force distalizer allowed obtaining the highest rate of molar distal movement from 2 force systems: 1 from the palatal and 1 from the buccal side, exerting pressure on the molars. The difference in the rate of distalization, however, might be clinically meaningless because distalization is usually followed by a phase of comprehensive treatment, which can cancel the effects of rapid distalization. Therefore, it is possible that a comparable overall treatment outcome can be achieved faster with the SAS rather than with the dual-force distalizer. Erupted second maxillary molars might affect the rate of distalization. According to Kinzinger et al 22 and Karlsson and Bondemark, 23 efficiency of distalization is greater if it is started before the eruption of the second molars. The results of this study, however, do not support this claim unambiguously. Although the greatest monthly distal movement of maxillary first molars was noted in the patients treated with the dual-force distalizer whose maxillary second molars were unerupted or just recently erupted, other groups differing in the number of erupted second molars showed comparable rates of distalization. 17 For example, in the samples investigated by Gelg or et al 8,12 and Polat-Ozsoy 18 the maxillary first molars were moved distally by 0.7 to 0.8 mm per month despite considerable differences in the percentages of erupted second molars. In the groups examined by Gelg or 8,12 approximately 90% of the second molars were erupted, whereas in the sample of Polat-Ozsoy et al 18 only 13.6% of second molars were present. These findings suggest that presence or absence of second molars might play a smaller role when implant- or miniplate-supported distalization appliances are used. The molars are usually distalized early during orthodontic therapy, and it is followed by other stages of comprehensive treatment. The position of the molars or the inclination of the incisors achieved during distalization might be affected during later stages of treatment. Therefore, 2 important issues should be considered before making conclusions regarding the effectiveness of TSADsupported distalizers. First, are the end-of-treatment outcomes with TSADs better than those obtained with alternative tooth-borne anchorage? Second, are outcomes with TSADs more stable than conventional methods? Unfortunately, no studies included in our review addressed these questions. All of them were focused on the shortterm effects of distalization. The lack of long-term evaluations necessarily weakened the conclusions. CONCLUSIONS On the basis of this systematic review, the following can be concluded. June 2011 Vol 139 Issue 6 American Journal of Orthodontics and Dentofacial Orthopedics

8 Fudalej and Antoszewska Orthodontic distalizers reinforced with the TSADs seem to be effective in molar distalization. They also appear to produce fewer unwanted side effects. 2. The methodologic soundness of the reviewed studies was relatively low. 3. The long-term effectiveness of TSAD-reinforced molar distalization should be studied. REFERENCES 1. Hilgers JJ. The pendulum appliance for Class II non-compliance therapy. J Clin Orthod 1992;26: Carano A, Testa M. The distal jet for upper molar distalization. J Clin Orthod 1996;30: Sfondrini MF, Cacciafesta V, Sfondrini G. Upper molar distalization: a critical analysis. Orthod Craniofac Res 2002;5: Antonarakis GS, Kiliaridis S. Maxillary molar distalization with noncompliance intramaxillary appliances in Class II malocclusion. A systematic review. Angle Orthod 2008;78: Cope JB. Temporary anchorage devices in orthodontics: a paradigm shift. Semin Orthod 2005;11: Sugawara J, Kanzaki R, Takahashi I, Nagasaka H, Nanda R. Distal movement of maxillary molars in nongrowing patients with the skeletal anchorage system. Am J Orthod Dentofacial Orthop 2006;129: Sugawara J, Daimaruya T, Umemori M, Nagasaka H, Takahashi I, Kawamura H, et al. Distal movement of mandibular molars in adult patients with the skeletal anchorage system. Am J Orthod Dentofacial Orthop 2004;125: Gelg or IE, Karaman AI, B uy ukyilmaz T. Comparison of 2 distalization systems supported by intraosseous screws. Am J Orthod Dentofacial Orthop 2007;131:161.e Centre for Reviews and Dissemination. Systematic Reviews. CRD s guidance for undertaking reviews in healthcare. York, United Kingdom: University of York NHS Centre for Reviews and Dissemination; The Cochrane Collaboration. In: Higgins JPT, Green S, editors. Cochrane handbook for systematic reviews of interventions. Chichester, United Kingdom: Wiley-Blackwell; p Higgins JP, Thompson SG, Deeks JJ, Altman DG. Measuring inconsistency in meta-analyses. BMJ 2003;327: Gelg or IE, B uy ukyilmaz T, Karaman AI, Dolanmaz D, Kalayci A. Intraosseous screw-supported upper molar distalization. Angle Orthod 2004;74: Escobar SA, Tellez PA, Moncada CA, Villegas CA, Latorre CM, Oberti G. Distalization of maxillary molars with the bone-supported pendulum: a clinical study. Am J Orthod Dentofacial Orthop 2007; 131: Kinzinger GS, G ulden N, Yildizhan F, Diedrich PR. Efficiency of a skeletonized distal jet appliance supported by miniscrew anchorage for noncompliance maxillary molar distalization. Am J Orthod Dentofacial Orthop 2009;136: Kircelli BH, Pektaş ZO, Kircelli C. Maxillary molar distalization with a bone-anchored pendulum appliance. Angle Orthod 2006;76: Onçag G, Seçkin O, Dinçer B, Arikan F. Osseointegrated implants with pendulum springs for maxillary molar distalization: a cephalometric study. Am J Orthod Dentofacial Orthop 2007;131: Oberti G, Villegas C, Ealo M, Palacio JC, Baccetti T. Maxillary molar distalization with the dual-force distalizer supported by mini-implants: a clinical study. Am J Orthod Dentofacial Orthop 2009;135:282.e Polat-Ozsoy O, Kircelli BH, Arman-Ozçirpici A, Pektaş ZO, Uçkan S. Pendulum appliances with 2 anchorage designs: conventional anchorage vs bone anchorage. Am J Orthod Dentofacial Orthop 2008;133:339.e Cornelis MA, De Clerck HJ. Maxillary molar distalization with miniplates assessed on digital models: a prospective clinical trial. Am J Orthod Dentofacial Orthop 2007;132: Park HS, Lee SK, Kwon OW. Group distal movement of teeth using microscrew implant anchorage. Angle Orthod 2005;75: Phillips B, Ball C, Sackett D, Badenoch D, Straus S, Haynes B, et al. Centre for Evidence-Based Medicine. Levels of evidence. Available at: Accessed on August 28, Kinzinger GS, Fritz UB, Sander FG, Diedrich PR. Efficiency of a pendulum appliance for molar distalization related to second and third molar eruption stage. Am J Orthod Dentofacial Orthop 2004;125: Karlsson I, Bondemark L. Intraoral maxillary molar distalization: movement before and after eruption of second molars. Angle Orthod 2006;76: American Journal of Orthodontics and Dentofacial Orthopedics June 2011 Vol 139 Issue 6