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Influence of interradicular and palatal placement of orthodontic mini-implants on the success (survival) rate
Head & Face Medicine volume 13, Article number: 14 (2017)
The purpose of this retrospective cohort study was to investigate the success rates of orthodontic mini-implants (OMIs) placed in different insertion sites and to analyse patient and site- related factors that influence mini-implant survival.
Three hundred eighty-seven OMIs were inserted in 239 patients for orthodontic anchorage and were loaded with a force greater than 2 N. Two different insertion sites were compared: 1. buccal inter-radicular and 2. palatal, at the level of the third palatal ruga. Survival was analysed for location and select patient parameters (age, gender and oral hygiene). The level of statistical significance was set at p < 0.05.
The overall success rate was 89.1%. There were statistically significant differences between insertion sites; success rate was 98.4% for OMIs placed in the anterior palate and 71% for OMIs inserted buccal between roots (p < 0.001).
Success rate of OMIs was primarily affected by the insertion site. The anterior palate was a more successful location compared to buccal alveolar bone.
The introduction of temporary anchorage devices (TADs) for skeletal anchorage in orthodontics promised to improve biomechanical possibilities for tooth movement [1, 2]; orthodontic mini-implants (OMIs) are the smallest TADs available . Due to their reduced size, OMIs can be inserted at various sites in both jaws .
OMIs are generally well accepted by patients ; they offer affordable support for anchorage demanding orthodontic biomechanics . Other TADs such as orthodontic mini-plates need soft tissue surgery and are comparatively complex to insert and use; insertion is usually undertaken by oral surgeons. OMIs however can be relatively easily placed and removed, causing little discomfort to the patient ; this can be undertaken by the orthodontist during a routine visit .
A large body of evidence on success rates [6, 8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35,36,37,38,39,40] of OMIs exists, showing an average of approximately 84% [8, 9]. However, considerable variation between different anatomical insertion sites has been reported . A meta-analysis of 52 studies on OMIs reported an overall failure rate of 13.5% .
Parasagittal insertion of OMIs in the anterior palate has one of the highest success rates . A prospective study of Straumann® palatal implants revealed success rates of 95.7% . A systematic review  showed that palatal implants have a better success rate compared to inter-radicular OMIs. The Straumann® palatal implant has a surface area of about 54 mm2 whilst two joined OMIs feature a larger combined surface area (2 × 45.34 mm2) . The success of OMIs may hence be correlated to an increased implant-to-bone contact area rather than the properties of the screws themselves or other proposed factors.
A number of orthodontic appliances, (e.g. for rapid palatal expansion (RPE)  or maxillary molar distalization ) utilise two OMIs that are usually inserted parasagittal in the anterior palate. Parasagittal insertion is mandatory for OMI-supported RPE, whereas various designs have been described for distalization of molars in the upper jaw, some of which use inter-radicular insertion sites .
Success rates greater than 80% [8, 9] should encourage orthodontists to use OMIs. Knowledge of insertion sites with high success rates is therefore crucial as it will affect clinical decision making. Success rates of two joined palatal OMIs have not yet been compared to success rates of appliances supported by inter-radicular insertion sites and to our knowledge no conclusive data on this subject is currently available.
The purpose of this retrospective cohort study was to investigate the success rates of orthodontic mini-implants (OMIs) placed either on the buccal side between roots of the teeth or palatally at the level of the third palatal ruga, and also to determine patient related factors that may have an impact on success rates.
All OMIs had identical dimensions (diameter 1.7 mm; length 8 mm), and were manufactured by the same company (OrthoEasy®, Forestadent, Pforzheim, Germany). Other inclusion criteria were: complete patient records including panoramic and cephalometric radiographs, intraoral photographs of applied orthodontic biomechanics and oral hygiene index measurements (Approximal Plaque Index (API) score) at every visit.
After application of the inclusion criteria, the search generated 239 patient records that were eligible for this investigation (137 females and 102 males). The median age of the patients was 13.8 years (interquartile range (IQR) 11.0–16.9 years). A total of 387 OMIs were inserted: 190 in the anterior palate and 197 in buccal inter-radicular sites.
All OMIs were inserted in a private orthodontic practice over a three years observation period. This implant system has an anodized surface, features a self-tapping and self-drilling design and is made from titanium-vanadium alloy (Ti-6Al-4 V). Following patient consultation and written consent, 0.2 ml to 0.5 ml of local anaesthetic were used (Ultracain® D-S, Sanofi-Aventis Deutschland GmbH, Frankfurt, Germany), and OMIs were inserted without soft tissue incision or predrilling. The OMIs were inserted at two different sites:
Palatal OMIs were loaded within 3 days after placement as the attached appliance had to be manufactured in a dental laboratory. All OMIs were used for direct anchorage. All biomechanics applied to the OMIs produced a force of >2 N and all palatal appliances worked bilaterally therefore exerting equal forces to both implants.
The palatal OMIs used in this study were either for maxillary molar distalization  (Fig. 2a), or rapid palatal expansion using a hybrid RPE (“hybrid hyrax”, Wilmes et al. ) (Fig. 2b). Both of these appliances were directly attached to the OMIs and exerted equal forces of (>2 N) per implant; the exact force values have been previously investigated elsewhere [46, 51].
OMIs remaining in situ over the entire period of treatment that required anchorage were recorded as successful. Premature loss or if removal of the OMI became necessary before achieving the defined treatment aims were charted unsuccessful.
Data collection and statistical analysis
All data were tabulated in a Microsoft Excel® 2007 file (Microsoft Corp., Richmond, Wash., USA). SPSS® for Windows version 22.0 (IBM Corp., Armonk, NY, USA) was used for all statistical analyses. The following parameters were analysed in relation to OMI success rates: 1) insertion site (anatomy); and 2) patient demographic data (age, gender and oral hygiene). Normal distribution of metrical parameters was assessed using Kolmogorov-Smirnov (K-S) tests. Comparisons between nominal variables were performed with the Pearson’s chi-squared test or Fisher’s exact test for non-parametric data. Continuous data not following a normal distribution were analysed using Mann-Whitney U test and descriptive statistics; median and interquartile range (IQR) are displayed accordingly. Survival rates were calculated with the Kaplan-Meier estimator, and their significance was evaluated with log rank tests. Additional Cox regression analysis of multiple variables was performed. Statistical significance was set at p < 0.05.
Three hundred twenty-eight out of 387 orthodontic mini-implants were considered successful; the overall success rate was 84.8% over the observation period.
Analysis by anatomical site
Significant differences in success rates were observed between the palatal and the inter-radicular insertion site (Table 1). The success rate of palatal OMIs was 98.9%. Only 2 out of 190 palatal OMIs were lost. Those were inserted in the same patient, providing anchorage for molar distalization; The implants had to be removed before the treatment objectives had been achieved because they were loose.
Interradicular OMIs were successful in 71.1% of the cases. There was no statistically significant difference in success rates between maxillary inter-radicular and mandibular inter-radicular OMIs (p = 0.628).
Analysis by patient factors
Patient parameters that were assessed included, age and gender (Table 2) and these parameters had an impact on success rates. OMIs inserted in patients older than 30 years were found to have a 29.5% failure rate compared to those used in younger patients that showed lower failure rates of 14.8% (20–30 years) and 13.3% (6–20 years). However, this difference was statistically significant only for the youngest group (6–20 years). A significant difference in success rates was also noted between male and female patients.
Survival rate analysis
Survival rates based on Kaplan-Meier estimates were calculated from day of insertion until day of implant loss, early or scheduled removal of mini-implants. 59 OMIs were either lost or removed prematurely. Analysis of survival rates for the anterior palate compared to inter-radicular insertion sites demonstrated a better performance of palatal OMIs (Fig. 3). Those remained in place for 24.4 months on average. Interradicular insertion showed higher loss rates in the first 13 months with an average survival of 17.4 months. The correlation between insertion site and the failure rate of OMIs was statistically significant (p < 0.001). The results of the Cox-Regression are displayed in Table 3.
During the last decade, numerous studies have assessed the success rates of orthodontic mini-implants [6, 8,9,10,11, 14, 16, 17, 19, 20, 22,23,24,25,26,27,28, 31, 32, 36, 38, 39] and reported values ranging between 66% and 100% . Results from these investigations reveal a mean success rate of 85.50% (median value 85.46%), which is very close to the results (83.6%) of two systematic reviews [8, 9]. The success rate of our retrospective cohort study (84.8%) is similar.
Approximately half (50.9%) of all OMIs in this study were inserted in the anterior palate, and 98.9% of those were successful. However, palatal OMIs were always inserted and used in pairs. Connecting two OMIs may be the reason for better stability due to the increased surface area of two mini-implants . Two palatal OMIs provide a nearly identical surface area as one standard size palatal implant. The failure rate of the latter has been reported to be between 4.3% and 9% [43, 53,54,55]. Only in one patient in our cohort both palatal OMIs were lost; these were providing skeletal anchorage for a distalization appliance.
Success rates were significantly influenced by the combination of load and insertion site. In our investigation palatal OMIs were nearly always successful. Buccal mini-implants were clearly less successful. 59 (15.3%) out of 387 inserted OMIs were lost, and 57 of those had been inserted buccal between roots to support space closure mechanics. It appears that the combination of inter-radicular insertion combined with the type of use resulted in a poorer survival rate.
Existing evidence suggests that moderate loading of OMIs is preferable [56, 57]. Osseointegrated dental implants, featuring treated surfaces, larger diameters and lengths, are probably better suited for the application of heavy loads . Bicortical insertion of OMIs has also been recommended for improved stability when heavy forces are applied [59, 60].
Anchorage design might have an effect on success rates. The findings of Antoszewska et al.  indicated that indirect use seemed to have a higher success rate (96.96%) than direct loading (92.60%) but this difference was not statistically significant. In our study, all OMIs were directly loaded, which might have influenced the success rate for buccal inter-radicular insertion (71.1%). In addition all directly loaded OMIs in the palate were joint to one appliance, while the buccal inter-radicular OMIs were used individually and this may have had an impact on success rates.
Other than oral hygiene, gender and age revealed statistically significant differences, but only for younger patients (6–20 years). It is remarkable that OMIs inserted in patients older than 30 years had a failure rate that was twice as high (29.5%) compared to those used in younger patients: 14.8% (20–30 years) and 13.3% (6–20 years), respectively. These differences might be explained by the fact that OMIs in the older patient group (>30 years) were mostly used for molar protraction with forces >2 N, with an associated success rate of 70.5%.
Throughout the entire study period, 59 of 387 OMIs were lost or removed prematurely with an average survival time of 24.4 months. OMIs inserted between roots demonstrated considerably higher loss rates within the first 5 months, with an average survival of 17.4 months. Consequently, the correlation between insertion site and loss of OMIs was highly significant (p < 0.001), confirming results from previous research [10, 39].
In summary, our investigation was a large retrospective cohort study and our results concur with previous research [24, 61]. Apart from location and application of OMI we also investigated selected patient related factors. To our knowledge this is the first time that success rates of two joined parasagittal palatal OMIs were compared to inter-radicular insertion sites, adding new data supporting the exiting body of evidence. Maybe not surprisingly the success rate of palatal OMIs of our study was very similar to that of the Straumann® palatal implant . This suggest that two joined palatal OMIs might be used as an alternative for a palatal implant; OMIs can be loaded immediately compared to palatal implants that require 12 weeks’ for osseointegration. However once osseointegrated, palatal implants remain absolutely stable when loaded compared to OMIs [62, 63]. A drawback of our investigation is the retrospective design which may have introduced bias and prospective data from a randomized trials may make results more reliable .
Extensive research has been undertaken [42, 65] trying to analyse risk factors for OMI failure but many questions remained unanswered . Further research, ideally using prospective randomized designs or a prospective cohort investigation in this field are needed.
This retrospective investigation demonstrated that the success rate of OMIs loaded with forces greater than 2 N was mainly affected by the site of their insertion. Two OMIs inserted in the anterior palate, joined together and used for direct anchorage offered survival rates close to 100%. Individually used OMIs inserted between roots in the buccal alveolus resulted in significantly lower (71.1%) success rates; there was no statistically significant difference for upper and lower buccal insertion sites.
Baumgaertel S, Razavi MR, Hans MG. Mini-implant anchorage for the orthodontic practitioner. Am J Orthod Dentofac Orthop. 2008;133:621–7.
Papadopoulos MA, Tarawneh F. The use of miniscrew implants for temporary skeletal anchorage in orthodontics: a comprehensive review. Oral Surg Oral Med Oral Pathol Oral Radiol Endod. 2007;103:6–15.
McGuire MK, Scheyer ET, Gallerano RL. Temporary anchorage devices for tooth movement: a review and case reports. J Periodontol. 2006;77:1613–24.
Baumgaertel S. Temporary skeletal anchorage devices: the case for miniscrews. Am J Orthod Dentofac Orthop. 2014;145:560.
Zawawi KH. Acceptance of orthodontic miniscrews as temporary anchorage devices. Patient Prefer Adherence. 2014;8:933–7.
Kuroda S, Sugawara Y, Deguchi T, Kyung HM, Takano-Yamamoto T. Clinical use of miniscrew implants as orthodontic anchorage: success rates and postoperative discomfort. Am J Orthod Dentofac Orthop. 2007;131:9–15.
American Association of Orthodontics (AAO). Temporary Anchorage Devices (TADs). For predictable tooth movement. [ https://nf.aaoinfo.org/eweb/DynamicPage.aspx?Action=Add&ObjectKeyFrom=1A83491A-9853-4C87-86A4F7D95601C2E&WebCode=ProdDetailAdd&DoNotSave=yes&ParentObject=CentralizedOrderEntry&ParentDataObject=Invoice%20Detail&ivd_formkey=69202792-63d7-4ba2-bf4e-a0da41270555&ivd_cst_key=00000000–0000–0000-0000-000000000000&ivd_prc_prd_key=0A27B9E1-2BE3-465F-B3E0-34C218E99CA1. Accessed: 13–07-2014 ].
Crismani AG, Bertl MH, Celar AG, Bantleon HP, Burstone CJ. Miniscrews in orthodontic treatment: review and analysis of published clinical trials. Am J Orthod Dentofac Orthop. 2010;137:108–13.
Schätzle M, Mannchen R, Zwahlen M, Lang NP. Survival and failure rates of orthodontic temporary anchorage devices: a systematic review. Clin Oral Implants Res. 2009;20:1351–9.
Antoszewska J, Papadopoulos MA, Park HS, Ludwig B. Five-year experience with orthodontic miniscrew implants: a retrospective investigation of factors influencing success rates. Am J Orthod Dentofac Orthop. 2009;136:158–9.
Baek SH, Kim BM, Kyung SH, Lim JK, Kim YH. Success rate and risk factors associated with mini-implants reinstalled in the maxilla. Angle Orthod. 2008;78:895–901.
Basha AG, Shantaraj R, Mogegowda SB. Comparative study between conventional en-masse retraction (sliding mechanics) and en-masse retraction using orthodontic micro implant. Implant Dent. 2010;19:128–36.
Berens A, Wiechmann D, Dempf R. Mini- and micro-screws for temporary skeletal anchorage in orthodontic therapy. J Orofac Orthop. 2006;67:450–8.
Chaddad K, Ferreira AF, Geurs N, Reddy MS. Influence of surface characteristics on survival rates of mini-implants. Angle Orthod. 2008;78:107–13.
Chen CH, Chang CS, Hsieh CH, Tseng YC, Shen YS, Huang IY, et al. The use of microimplants in orthodontic anchorage. J Oral Maxillofac Surg. 2006;64:1209–13.
Chen YJ, Chang HH, Huang CY, Hung HC, Lai EH, Yao CC. A retrospective analysis of the failure rate of three different orthodontic skeletal anchorage systems. Clin Oral Implants Res. 2007;18:768–75.
Cheng SJ, Tseng IY, Lee JJ, Kok SH. A prospective study of the risk factors associated with failure of mini-implants used for orthodontic anchorage. Int J Oral Maxillofac Implants. 2004;19:100–6.
Hedayati Z, Hashemi SM, Zamiri B, Fattahi HR. Anchorage value of surgical titanium screws in orthodontic tooth movement. Int J Oral Maxillofac Surg. 2007;36:588–92.
Justens E, De Bruyn H. Clinical outcome of mini-screws used as orthodontic anchorage. Clin Implant Dent Relat Res. 2008;10:174–80.
Lee SJ, Ahn SJ, Lee JW, Kim SH, Kim TW. Survival analysis of orthodontic mini-implants. Am J Orthod Dentofac Orthop. 2010;137:194–9.
Lim HJ, Eun CS, Cho JH, Lee KH, Hwang HS. Factors associated with initial stability of miniscrews for orthodontic treatment. Am J Orthod Dentofac Orthop. 2009;136:236–42.
Luzi C, Verna C, Melsen B. A prospective clinical investigation of the failure rate of immediately loaded mini-implants used for orthodontic anchorage. Prog Orthod. 2007;8:192–201.
Luzi C, Verna C, Melsen B. Guidelines for success in placement of orthodontic mini-implants. J Clin Orthod. 2009;43:39–44.
Manni A, Cozzani M, Tamborrino F, De Rinaldis S, Menini A. Factors influencing the stability of miniscrews. A retrospective study on 300 miniscrews. Eur J Orthod. 2011;33:388–95.
Miyawaki S, Koyama I, Inoue M, Mishima K, Sugahara T, Takano-Yamamoto T. Factors associated with the stability of titanium screws placed in the posterior region for orthodontic anchorage. Am J Orthod Dentofac Orthop. 2003;124:373–8.
Mommaerts MY, Michiels ML, De Pauw GA. A 2-year outcome audit of a versatile orthodontic bone anchor. J Orthod. 2005;32:175–81.
Moon CH, Lee DG, Lee HS, Im JS, Baek SH. Factors associated with the success rate of orthodontic miniscrews placed in the upper and lower posterior buccal region. Angle Orthod. 2008;78:101–6.
Moon CH, Park HK, Nam JS, Im JS, Baek SH. Relationship between vertical skeletal pattern and success rate of orthodontic mini-implants. Am J Orthod Dentofac Orthop. 2010;138:51–7.
Motoyoshi M, Yoshida T, Ono A, Shimizu N. Effect of cortical bone thickness and implant placement torque on stability of orthodontic mini-implants. Int J Oral Maxillofac Implants. 2007;22:779–84.
Oh YH, Park HS, Kwon TG. Treatment effects of microimplant-aided sliding mechanics on distal retraction of posterior teeth. Am J Orthod Dentofac Orthop. 2011;139:470–81.
Park HS. Clinical study on success rate of microscrew implants for orthodontic anchorage Korean J Orthod. 2003;33:151–6.
Park HS, Jeong SH, Kwon OW. Factors affecting the clinical success of screw implants used as orthodontic anchorage. Am J Orthod Dentofac Orthop. 2006;130:18–25.
Park HS, Lee SK, Kwon OW. Group distal movement of teeth using microscrew implant anchorage. Angle Orthod. 2005;75:602–9.
Park HS, Yoon DY, Park CS, Jeoung SH. Treatment effects and anchorage potential of sliding mechanics with titanium screws compared with the tweed-Merrifield technique. Am J Orthod Dentofac Orthop. 2008;133:593–600.
Santiago RC, de Paula FO, Fraga MR, Picorelli Assis NM, Vitral RW. Correlation between miniscrew stability and bone mineral density in orthodontic patients. Am J Orthod Dentofac Orthop. 2009;136:243–50.
Tsaousidis G, Bauss O. Influence of insertion site on the failure rates of orthodontic miniscrews. J Orofac Orthop. 2008;69:349–56.
Tseng YC, Hsieh CH, Chen CH, Shen YS, Huang IY, Chen CM. The application of mini-implants for orthodontic anchorage. Int J Oral Maxillofac Surg. 2006;35:704–7.
Viwattanatipa N, Thanakitcharu S, Uttraravichien A, Pitiphat W. Survival analyses of surgical miniscrews as orthodontic anchorage. Am J Orthod Dentofac Orthop. 2009;136:29–36.
Wiechmann D, Meyer U, Buchter A. Success rate of mini- and micro-implants used for orthodontic anchorage: a prospective clinical study. Clin Oral Implants res. 2007;18:263–7.
Woo SS, Jeong ST, Huh YS. Hwang: a clinical study of the skeletal anchorage system using miniscrews. J Korean Oral Maxillofacial Surg. 2003;29:102–7.
Tsui WK, Chua HD, Cheung LK. Bone anchor systems for orthodontic application: a systematic review. Int J Oral Maxillofac Surg. 2012;41:1427–38.
Papageorgiou SN, Zogakis IP, Papadopoulos MA. Failure rates and associated risk factors of orthodontic miniscrew implants: a meta-analysis. Am J Orthod Dentofac Orthop. 2012;142:577–95. e577
Männchen R, Schatzle M. Success rate of palatal orthodontic implants: a prospective longitudinal study. Clin Oral Implants res. 2008;19:665–9.
Nienkemper M, Wilmes B, Pauls A, Drescher D. Multipurpose use of orthodontic mini-implants to achieve different treatment goals. J Orofac Orthop. 2012;73:467–76.
Wilmes B, Nienkemper M, Drescher D. Application and effectiveness of a mini-implant- and tooth-borne rapid palatal expansion device: the hybrid hyrax. World J Orthod. 2010;11:323–30.
Ludwig B, Glasl B, Kinzinger GS, Walde KC, Lisson JA. The skeletal frog appliance for maxillary molar distalization. J Clin Orthod. 2011;45:77–84.
Ozkalayci N, Yetmez M. A new orthodontic appliance with a mini screw for upper molar Distalization. Appl Bionics Biomech. 2016;5728382:27.
Ludwig B, Glasl B, Kinzinger GS, Lietz T, Lisson JA. Anatomical guidelines for Miniscrew insertion: vestibular Interradicular sites. J Clin Orthod. 2011;45:165–73.
Ludwig B, Glasl B, Bowman SJ, Wilmes B, Kinzinger GS, Lisson JA. Anatomical guidelines for miniscrew insertion: palatal sites. J Clin Orthod. 2011;45:433–41. quiz 467
Hourfar J, Ludwig B, Bister D, Braun A, Kanavakis G. The most distal palatal ruga for placement of orthodontic mini-implants. Eur J Orthod. 2015;37:373–8.
Sander C, Huffmeier S, Sander FM, Sander FG. Initial results regarding force exertion during rapid maxillary expansion in children. J Orofac Orthop. 2006;67:19–26.
Wilmes B, Drescher D, Nienkemper M. A miniplate system for improved stability of skeletal anchorage. J Clin Orthod. 2009;43:494–501.
Asscherickx K, Vannet BV, Bottenberg P, Wehrbein H, Sabzevar MM. Clinical observations and success rates of palatal implants. Am J Orthod Dentofac Orthop. 2010;137:114–22.
Jung BA, Kunkel M, Gollner P, Liechti T, Wehrbein H. Success rate of second-generation palatal implants. Angle Orthod. 2009;79:85–90.
Jung BA, Kunkel M, Gollner P, Liechti T, Wagner W, Wehrbein H. Prognostic parameters contributing to palatal implant failures: a long-term survival analysis of 239 patients. Clin Oral Implants Res. 2012;23:746–50.
Owens SE. Clinical and biological effects of the mini implant for orthodontic anchorage: an experimental study in the beagle dog. Tex Dent J. 2005;122:672.
Büchter A, Wiechmann D, Koerdt S, Wiesmann HP, Piffko J, Meyer U. Load-related implant reaction of mini-implants used for orthodontic anchorage. Clin Oral Implants Res. 2005;16:473–9.
De Pauw GA, Dermaut L, De Bruyn H, Johansson C. Stability of implants as anchorage for orthopedic traction. Angle Orthod. 1999;69:401–7.
Brettin BT, Grosland NM, Qian F, Southard KA, Stuntz TD, Morgan TA, et al. Bicortical vs monocortical orthodontic skeletal anchorage. Am J Orthod Dentofac Orthop. 2008;134:625–35.
Morarend C, Qian F, Marshall SD, Southard KA, Grosland NM, Morgan TA, et al. Effect of screw diameter on orthodontic skeletal anchorage. Am J Orthod Dentofac Orthop. 2009;136:224–9.
Melo AC, Andrighetto AR, Hirt SD, Bongiolo AL, Silva SU, Silva MA. Risk factors associated with the failure of miniscrews - a ten-year cross sectional study. Braz Oral Res. 2016;30
Liou EJ, Pai BC, Lin JC. Do miniscrews remain stationary under orthodontic forces? Am J Orthod Dentofac Orthop. 2004;126:42–7.
Nienkemper M, Handschel J, Drescher D. Systematic review of mini-implant displacement under orthodontic loading. Int J Oral Sci. 2014;6:1–6.
Vandenbroucke JP. Observational research, randomised trials, and two views of medical science. PLoS med. 2008;5:0050067.
Dalessandri D, Salgarello S, Dalessandri M, Lazzaroni E, Piancino M, Paganelli C, et al. Determinants for success rates of temporary anchorage devices in orthodontics: a meta-analysis (n > 50). Eur J Orthod. 2014;36:303-13.
The authors express their thanks to Mrs. J. Pasch for participating in the collection of data.
Availability of data and materials
For confidentiality issues, the data will only be shared in aggregate form as presented in the tables.
JH conceived the project, gathered and processed the data, created the material presented (tables, electronic images, references, et cetera) and drafted the manuscript. JAL, DB and GK critically revised the manuscript. BL reviewed the process and critically revised the manuscript. All authors read and approved the final manuscript.
The authors declare that they have no competing interests.
Consent for publication
Ethics approval and consent to participate
Ethical approval for the use of existing radiographic material was granted (No 224/13, Ärztekammer des Saarlandes, Saarbrücken, Germany). Written consent is available for all patients.