The extent of root resorption and tooth movement following the ...

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Original article

The extent of root resorption and tooth movement following the application of ascending and descending magnetic forces: a prospective split mouth, microcomputed-tomography studyTiffany Teen Yu Huang1, Selma Elekdag-Turk2, Oyku Dalci1, Mohammed Almuzian1,3,4, Ersan Ilsay Karadeniz1,5, Carmen Gonzales1, Peter Petocz1,6, Tamer Turk2 and M. Ali Darendeliler1

1Discipline of Orthodontics, Faculty of Dentistry, University of Sydney, Australia, 2Department of Orthodontics, Faculty of Dentistry, Ondokuz Mayis University, Samsun, Turkey, 3Department of Orthodontics, John Radcliffe Hospitals, Oxford University Hospitals, Oxford, 4Department of Orthodontics, Eastman Dental Institute, London, UK, 5Department of Orthodontics, Faculty of Dentistry, Karadeniz Technical University, Trabzon, Turkey, and 6Department of Statistics, Macquarie University, Sydney, Australia

Correspondence to: Mohammed Almuzian, Department of Orthodontics, Second floor, John Radcliffe Hospitals, Oxford Uni-versity Hospitals NHS Trust Foundation, Oxford, UK. E-mail: [email protected]

Summary

Objective: Various factors have been examined in the literature in an attempt to reduce the incidence and severity of root resorption. The purpose of the present investigation is to test the null hypothesis that there is no difference in relation to force level using gradually increasing (ascending) and decreasing (descending) orthodontic force generated by magnets on the severity of Orthodontically Induced Inflammatory Iatrogenic Root Resorption (OIIRR) and amount of tooth movement.Methods: Twenty maxillary first premolars from 10 patients were subjected to ascending (25–225 g, magnets in attraction) and descending (225 to 25 g, magnets in repulsion) buccal forces using a split mouth design over an 8-week period. Polyvinyl siloxane impressions were taken at week 0, 4, and 8 to record the tooth movement. After 8 weeks, the teeth were extracted, scanned, with micro-CT in 16.9 µm resolution, and the root resorption craters were localized circumferentially and quantified at each level of the root.Results: The total volume of OIIRR with ascending force was 1.20 mm3, and with descending force was 1.25 mm3, and there was no statistically significant difference between them. OIIRR on the palatal surface (0.012 mm3) was significantly less than on the buccal surface (0.057 mm3) and than on the mesial surface (0.035 mm3). There is no statistically significant difference in the degree of OIIRR between different level of the root (cervical, middle, and apical) at different surfaces. Moreover, the amount of tooth movement, at 0-, 4-, and 8-week interval, secondary to an ascending and descending force application was not statistically significant.Conclusions: There is no short-term (8 weeks) statistically significant difference between orthodontic ascending and descending forces, from 25 to 225 g and from 225 to 25 g, respectively, in term of severity and location of OIIRR as well as the amount of tooth movement. The buccal surface of the root showed highest degree of OIIRR compared to other root’s surfaces.

European Journal of Orthodontics, 2017, 547–553doi:10.1093/ejo/cjw073

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Introduction

Orthodontically induced iatrogenic inflammatory root resorption (OIIRR) (1) is the pathological inflammatory process that results in loss of mineralized cementum and dentine concurrent with removal of hyalinized tissue (2–4).

Orthodontic force magnitude has been shown to be a major fac-tor in OIIRR in many animal (5–7) and human (8–11) studies. Light forces have been recommended to reduce adverse tissue reactions (3, 12). Recent series of studies by Darendeliler et al. (13–15) dem-onstrated the force magnitude as a significant factor for the extent of root resorption (RR) with the heavy force group having 3.31-folds greater amount of RR than light force group. These findings were similar to the findings of Weltman et al. (16) in their system-atic review. In contrast, some other studies proposed no relationship between force magnitude and severity of OIIRR (17, 18).

The relationship between force magnitude delivered by orthodon-tic appliances and the rate of orthodontic tooth movement remains controversial. According to Quinn and Yoshikawa (19), the rate of tooth movement is related to the force magnitude applied. In a human study, heavy force application demonstrated an increased amount of tooth movement in canine distalization (20). In contrast, it was also shown that light force produced more tooth movement after 28 days (6). However, others proposed that there is no direct relation-ship between force magnitude, type of tooth movement, and amount of displacement in both animal (21) and human studies (22). Using a mathematic model, Ren et al. (23) concluded that neither optimal force nor force range could be calculated to produce maximum tooth movement. Variables previously mentioned, such as alveolar bone density, force magnitude, direction, distribution, and duration need to be considered in obtaining optimal tooth movement.

The relationship between gradually increasing orthodontic force and OIIRR is controversial; some showed a direct and significant correlation (17, 18), while other demonstrated no relationship (24).

Magnets have a wide range of clinical applications in orthodon-tics, for example intrusion (25), expansion (26), forced eruption of impacted teeth (27, 28), and functional appliances (29, 30). In addition, magnets have been used in orthodontic tooth movement during complex intra- and inter-arch mechanics (31), molar distali-zation (32, 33), without arch wires (34), and as magnetic edgewise brackets (35, 36). Force consistency and continuity are vital in an optimal orthodontic force system (37). Apart from superelastic NiTi; orthodontic force application uncontrollably decreases over time and tooth movement. Using magnets, it is possible to deliver gradual change in force magnitude, with the force produced by the magnets inversely proportional to the square of the distance between them, this means that the force between any magnets falls dramatically with distance (38). In addition, magnets deliver predictable force lev-els and provide frictionless mechanics (39, 40).

The force magnitude in the initial phase of tooth movement is important because of the dominance of significant metabolic changes during this stage (41) and the general consensus in the literature rec-ommend continuous light force, that is tooth movement by frontal (direct) resorption with minimal hyalinized (indirect) or necrotic changes that is associated with OIIRR (2). The effects of increasing (ascending) or decreasing (descending) orthodontic forces, which are possible by the use of magnets, on OIIRR and tooth movement are inconclusive. In the current literature, the two studies investigating the effects of magnets on tooth movement and OIIRR were done on rats (24, 42). However, currently there is no reported human studies of OIIRR and tooth movement utilizing both ascending and descending forces using magnetic appliances.

The aim of this split mouth study was, therefore, to investi-gate the correlation between gradually increasing (ascending) and decreasing (descending) force, generated by magnet, and the result-ant movement and OIIRR. The null hypothesis is that there is no difference in the amount of tooth movement and OIIRR between ascending and descending magnetic orthodontic force.

Materials and methods

Sample size using the Researcher’s Toolkit calculator indicated that a power of 90 per cent with beta error level of 20 per cent, clinical significance of 0.24 for OIIRR (on cube root scale) and 1 mm for tooth movement would require a data from 16 teeth. Accordingly, 20 maxillary first premolar teeth were collected, to overcome the potential drop out and exclusion, from 10 patients (7 females, 3 males, mean age 15.8 years; range 14.5–17.4 years) who required bilateral extractions for orthodontic purposes at the University of Ondokuz Mayis, Samsun, Turkey. Ethical approvals were obtained from the University of Ondokuz Mayis Medical Faculty Ethics Committee and from the Human Research Ethics Committee at the University of Sydney (ethics approval numbers EK:273 and X09-0277, respectively). The inclusion and exclusion criteria were, as previously described by Yee et al. (20): 1. minimal crowding on each side of the maxillary arch, 2. no craniofacial anomalies, 3. no signifi-cant medical history nor medication(s) that would adversely affect the development or structure of the teeth and jaws and any subse-quent tooth movement, 4. no previous orthodontic or orthopaedic treatment, 5. tooth is vital, in normal function, and not previously restored, 6. no history of trauma, bruxism, or parafunction, and 7. no past or present signs and symptoms of periodontal disease.

Written informed consents were obtained from patients and/or guardians. At the start of the treatment a full records were collected including extra-oral and intra-oral photograph, study model, ortho-pantograph (OPG), and lateral cephalograph. The subjects’ upper first molars were banded with a passive trans-palatal arch (Figure 1). This provided a transverse and anterior–posterior anchorage, so the tooth movements are fully expressed on the experimental teeth, the first premolars. A bite block made of light cure band adhesive (TransBond Plus, 3M Unitek, California, USA) bonded on occlusal surface of molars and acted as an occlusal stop to prevent occlusal interferences. First premolars brackets (3M Unitek) were bonded on the first premolars.

The magnetic force system (MFS) consisted of two components. The first component (MFS1) involved a full dimension 0.019 inch × 0.025 inch stainless steel (SS) cantilever wire extended from the molar buccal tube to the region of the first premolar. The second component (MFS2) comprised of a circular shape with a centred-hole magnet soldered to the end of another sectional 0.019 inch × 0.025 inch SS wire (guiding pin). On the descending force side (DF),

Figure 1. Diagrammatic presentation of appliance design, occlusal view.

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MFS2 was passed through the hole of MFS1 and its guiding pin bonded by composite to the buccal surface of the premolar surface thus MFS2 lied lateral to MFS1. On the ascending force side (AF), MFS2 was bonded directly to the buccal surface of the premolars while its guiding pin passed through the hole of MFS1 thus MFS2 lied medial to MFS1. These configurations in the MFS were adopted to allow buccal movement of premolars in both AF and DF sides. The AF and DF were produced by the polarity of magnets in attrac-tion or repulsion, respectively. The DF was applied to the premolar on the right side (DF side), whereas the contralateral premolar was exposed to the AF in each case (AF side).

On the AF side, the distance between the magnets was initially more than 1 mm indicating a force of approximately 25 g that increased gradually as the premolar moves buccally to reach a level of 225 g when the magnets are in contact. On the DF side, the two repulsive magnets was initially in contact generating a force level of 225 g which dissipates as teeth move buccaly to reach a level of 25 g.

The magnets used in this study were neodymium-iron-boron magnets (Nd-Fe-B, AMF Magnetics, Sydney, Australia) with Nickel and Copper coating (15–20 µm) and had the following dimen-sions: outer diameter = 5 mm, inner diameter = 1 mm, and thick-ness = 0.75 mm (Figures 2 and 3). These magnets produced the force magnitude ranging from 25 to 225 g as depicted by the force–dis-placement graph (Figure 4). Using the Mach-1 Universal testing machine (Biosyntech, Inc., Quebec, Canada) with a 10 kg load cell and a customized mounting jig, force measurement (in grams) was commenced with the magnetic pair in contact initially and then the magnets were vertically separated 10 mm at a speed of 12 mm/min.

The subjects were assessed every 4 weeks to ensure the experimen-tal appliances were in good condition. In addition, a maxillary arch impression with polyvinyl siloxane material (Imprint II Regular Body/Light Body, 3M ESPE, St Paul, Minnesota, USA) was taken at three time points: Week 0 (appliance placement) as baseline record, Week 4, and Week 8 (appliance removal). Impressions were poured with die stone (Vel-mix, Kerr, Orange, California, USA). In order to quantify the amount of tooth movement, the casts were scanned with OpenScan 3D Laser Scanner (Laserdenta, GmbH Germany). Stable palatal reference

points including the first three palatal rugae (43, 44) and the most inferior point of the buccal and lingual cusp tips of the first premo-lars were marked on digitized models with VG Studio Max v.2.0. This scanner provides a resolution as high as 20 micron (0.02 mm) in each scan. STereoLithography (STL) formatted files of each patients were procrusted over each other (superimposed by matching the reference points in three dimensional space). The rate of tooth movement was determined by the measuring buccal and palatal cusps movements sep-arately and averaging (Figure 5). Each measurement was repeated four times and the mean value was calculated for each sample and exported to an excel sheet for statistical analysis.

After 8 weeks of experimentation, the first premolar teeth were extracted carefully to prevent surgical trauma to the root cementum. The extracted teeth were immediately stored in labelled contain-ers containing sterilized deionized water. Each tooth was placed in ultrasonic bath for 10 minutes to loosen all traces of residual peri-odontal ligament and soft tissue fragments which were subsequently removed by dampened gauze with a rubbing motion. The teeth were then disinfected in 70 per cent alcohol for 30 minutes and bench dried at ambient room temperature (23°C ± 1°C) for 24 hours.

A desktop X-ray micro-tomography system (SkyScan 1172, SkyScan N.V., Aartselaar, Belgium), capable of achieving near 1 × 10–7 cubic mm voxel size, was used to scan each tooth three-dimensionally. Prior to scanning the teeth, a new flat field reference was acquired to correct for sensor non-uniformity and ensures the sensor is in optimal working condition. Teeth was rotated over 360° at 0.2° rotation steps, scanned with X-rays at a voltage of 100 keV and 100 µA current. The high camera resolution setting produced an image matrix of 1500 × 1048 pixels, 1800 projections, frame averaging of 4, and random movement amplitude of 20 lines on the camera. In addition, geometrical correction, median filtering, and flat field correction were applied. A 1.0 mm thick aluminium filter was placed in front of the detector and the resulting X-ray energy spec-trum had an effective mean energy of approximately 60 keV.

The resulting 2D shadow/transmission images (16 bit TIF) were used to reconstruct the 3D object by using a 3D cone beam reconstruction algorithm (NRecon, Version 1.4.2). Beam hardening

Figure 2. Diagram of magnet appliance system, at ascending and descending side, and magnets.

Figure 3. Intraoral view of appliance in situ. (A) Maxillary right, (B) occlusal, and (C) left views.

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artifact was corrected by preselecting a correction level that mini-mized the artifact shown in the preview image, typically a value of 70–80 in the NRecon software was chosen. A resulting dataset of isotropic 16.9 µm voxel size resolution was achieved and the data was maintained at 16 bit TIF information.

For visualization and analysis of three dimensional/volumetric data, VGStudio Max 1.2 (Volume Graphics GmbH, Heidelberg, Germany) was used to analyse root resorption craters. The root sur-faces, extending from the cemneto-enamel junction (CEJ) to the api-cal end, on buccal, lingual, mesial, and distal aspects were divided equally into three-thirds (cervical, middle, apical). Positive identifica-tion of craters was confirmed by scrolling through axial and sagit-tal slices. The resorption craters were located individually, isolated by limiting coordinates in three planes of space in VGStudiomax. The data was then exported to convex hull software (Chull 2D, University of Sydney) to provide a direct measure of the concave volume of the three-dimensional data set.

Statistical analysisSPSS version 18 (SPSS, Chicago, Illinois, USA) was used for statis-tical analysis. A general linear model was used to investigate the differences in total OIIRR between subjects using AF and DF. As Kolmogorov–Smirnov test showed that data were not normally distributed, the cube root transformation was used to obtain nor-mality and thus enabling parametric statistical analysis. The analy-sis was carried out using the cube root of the total volume of RR as the response variable in order to satisfy the statistical assumptions required for application of these techniques. It essentially meas-ures the amount of resorption by the radius (mm) of an equivalent hemispherical crater rather than by the volume in mm3 and has been employed by this research team in previous studies (16, 45).

The analyses included the subject as a random factor; and the force, surface, and height as the fixed factors. The paired t-tests were used to determine the significance of intra-individual

differences in OIIRR between ascending and descending forces. The differences in tooth movement between ascending and descending forces were also examined by paired t-tests. Twenty-five per cent of sample was rescanned and the standard error of measurement for RR crater volumes was less than 2 per cent of the actual mean measurement.

Results

Ascending and descending magnetic forces produced root resorption in all teeth after 8 weeks of force application. The total mean volume of root resorption with ascending force was 1.20 mm3, the descend-ing force was 1.25 mm3, and there was no statistically significant difference between them (Figure 6). A power analysis indicated that the sample size used had a 90 per cent power of picking up a differ-ence of 0.24 (on cube root scale) if it existed. The actual difference found (0.03 on the cube root scale) was much smaller than this, and hence non-significant.

Using an ANOVA model for crater volume with root surface, vertical thirds, ascending, and descending forces as fixed factors and subject as random factor, there was no significant effect of type of magnetic force (ascending versus descending, P = 0.11, Figure 6) or vertical thirds (cervical, middle, and apical, P = 1.00, Figure 7). However, there were marginally significant differences between the amount of root resorption on different tooth surfaces (P = 0.04), with the highest OIIRR on buccal surface, less resorption on mesial and distal surface and least OIIRR on palatal side of the root (Figure 7).

After 4 weeks of forces application, the tooth movement was 0.94 ± 0.33 and 1.00 ± 0.39 mm at AF and DF side, respectively. While at 8 weeks, the total tooth movement was 1.40 ± 0.46 and 1.74 ± 0.53 mm, respectively (Figure 8). However, there was no sig-nificant difference between the groups (difference = 0.34, P = 0.136). With the sample size used, there was a greater than 90 per cent chance of picking up a difference of 1 mm if it existed. The actual difference in movement of 0.34 mm was much less than this, and hence was not found to be significant.

Discussion

Extensive research on OIIRR, the inevitable iatrogenic-effect of orthodontic treatment, encompasses the common goal of employing the most efficient and effective force application to create desired tooth movement whilst causing minimal OIIRR. The different char-acteristic changes in magnitude of the force were considered to be a factor that may contribute to the extent of OIIRR.

This study identified the presence of OIIRR craters on human premolar teeth after application of either ascending or descending forces, and OIIRR craters were quantified using micro-CT. Our study demonstrated that the volume of OIIRR for both ascend-ing (1.20 mm3) and descending (1.25 mm3) force application sides were comparable, and there was no statistically significant differ-ence between them. Although, it was difficult in our study to assess exactly how much force was being applied at the three time points due to narrow function-distance (Figure 4), this finding is compa-rable to Owman-Moll (17, 18), who postulated that the severity of OIIRR (extension and depth of resorbed root contour and size of root area on histological sections) did not differ significantly when the applied force (50 cN) was doubled to 100 cN and increased fourfold to 200cN. Using attractive magnets initially placed apart, it was postulated that ascending forces, as the force levels would start off light, would induce the smooth progression of tooth movement

Figure 4. Magnetic attachment force–distance graph.

Figure 5. 3D superimposition on palatal rugae to measure tooth movement. Initial, in red; after treatment, in green.


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by frontal resorption, before the gradual increase in force magnitude as the magnets move closer together. However, as magnets move closer, force levels might reach levels above physiological limits and start inducing OIIRR; which might explain the similar extent of

OIIRR observed for AF and DF sides comparable to that of OIIRR values found in previous heavy force studies (14). Another possible explanation for the similar OIIRR craters between the ascending and descending force is because the higher end of the force range in both ascending (25–225 g) and descending (225 to 25 g) groups highly exceed the capillary blood pressure (20–25 g/cm3) (46). As a result, both groups were subjected to high level of force during the experimental period and that caused periodontal ischemia and subsequent OIIRR.

The OIIRR seen on the DF side was not surprising as the ini-tial force levels were similar to that of previous studies using heavy forces (47). However, the results of our AF side are in contrast to the animal study in rats by Tomizuka et al. (24) which demonstrated effective tooth movement using increasing magnetic force with no pathological changes such as OIIRR.

Significantly large volume of OIIRR at cervical region of the buc-cal surface and the apical region on the palatal surface. This was consistent with the buccal tipping movement in which the cervical region of the buccal surface and the apical region on the palatal surface being the pressure areas of buccal tipping movement (47).

As mentioned, our trial found no significant short-term differ-ence (8 week) among the groups with different force level in regard to teeth movement. Previous human study assessing tooth movement under light and heavy forces demonstrated that the force magnitude was not related to the amount of tooth movement in the initial experimental period (Weeks 0–4); however, heavy force application was associated with increased amount of tooth movement in the later periods (Weeks 5–8 and Weeks 9–12) (20). This is contradicting

Figure 6. Volume of root resorption craters at AF and DF side represented using box-and-whisker diagram. Horizontal line within the boxplot represents median, vertical line from the boxes (whiskers) indicating variability outside the upper and lower quartiles, stars and circular points represent the observation point (outliner) (P = 0.11).

Figure 7. Volume of resorption craters at different radicular locations using box-and-whisker diagram (P = 0.04).

Figure 8. Box plot for the tooth movement for the ascending and descending forces using box-and-whisker diagram (P = 0.136).


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with the randomized control trial of Samuels et al. (48) who found that a faster tooth movement at low force level (100 g) compared to higher level (150 and 200 g). This could be explained on the ground that in our study a frictionless force system was used which is rela-tively more accurate than that in Samuels’ study in which sliding friction technique might disseminate the force magnitude.

On the contrary, in an animal study on rats comparing the amount of tooth movement with light and heavy forces, the initial tooth movement (until Day 3) was not found to be different; how-ever, from Day 4 to 28, the molars have moved forwards significantly more in the light force group compared to the heavy force group (6, 49). Using beagle dogs and skeletal anchorage, it was reported that molar moved faster with 300 cN than with 10 cN; and that, the effect of force magnitude on tooth movement had a positive dose-response relation only in the very low force range, and at higher force ranges (600 cN), no effect could be established (50). As our study design included ascending and descending forces, the force reached high lev-els either at the initial stage for descending force group or towards the later stages in the ascending force group, which then might have affected tooth movement in both groups during different stages.

Although split mouth study limited the inter-individual vari-ability but it should be acknowledged that the intra-individual vari-ability might bias the finding of this study especially when the data were pooled, in particular the effect of gender pooling (51–54), when treated in aggregation.

Additionally, it is worth mentioning that the sample size in this study was small, though the statistical power analysis indicated that the sample investigated was large enough to detect a significant dif-ference if there was one present.

A number of contributing factors may have influenced the minor and statistically non-significant differences in OIIRR and tooth movement between the ascending and descending force groups observed in this study. For instance, the duration of treatment (8 weeks) and the distance of tooth movement (buccal tipping) in this study may not be sufficient to detect the presence of potential dif-ferences between ascending and descending forces. In addition, as previously mentioned, the force range of both groups produced high force level during the experiment. Future studies could employ longer treatment duration and larger tooth movement range (such as distalization after extraction) and reduced heavy force levels. Finally, although the objective of using magnet was to eliminate friction but the use of guiding pin is believed to add a light friction that thought to be negligible compared to conventional orthodontic force system.

Conclusions

The null hypothesis was accepted and thus variable orthodontic force level using buccally directed ascending and descending forces, do not cause short-term (8 weeks) difference in the amount of OIIRR or tooth movement. Application of either ascending or descending orthodontic forces using magnets had comparable OIIRR to other conventional force. The buccal surface of the root showed highest degree of OIIRR compared to other root’s surfaces.

AcknowledgementsWe acknowledge the Australian Society of Orthodontists Foundation for Research and Education for their financial assistance of this research. The authors also thank Professor William Walsh of the University of New South Wales and Mr Dennis Dwarte of the Australian Centre for Microscopy and Microanalysis for the facilities and the scientific and technical assistance.

Conflict of interestThere is no financial interests or connections, direct or indirect, or other situations that might raise the question of bias in the work reported or the conclusions, implications or opinions stated—including pertinent commercial or other sources of funding for the individual author(s) or for the associated department(s) or organization(s), personal relationships, or direct academic competition.

References 1. Brezniak, N. and Wasserstein, A. (2002) Orthodontically induced inflam-

matory root resorption. Part I: the basic science aspects. The Angle Ortho-dontist, 72, 175–179.

2. Brudvik, P. and Rygh, P. (1994) Multi-nucleated cells remove the main hyalinized tissue and start resorption of adjacent root surfaces. European Journal of Orthodontics, 16, 265–273.

3. Reitan, K. (1974) Initial tissue behavior during apical root resorption. The Angle Orthodontist, 44, 68–82.

4. Rygh, P. (1977) Orthodontic root resorption studied by electron micros-copy. The Angle Orthodontist, 47, 1–16.

5. Dellinger, E.L. (1967) A histologic and cephalometric investigation of premolar intrusion in the Macaca speciosa monkey. American Journal of Orthodontics, 53, 325–355.

6. Gonzales, C., Hotokezaka, H., Yoshimatsu, M., Yozgatian, J.H., Darende-liler, M.A. and Yoshida, N. (2008) Force magnitude and duration effects on amount of tooth movement and root resorption in the rat molar. The Angle Orthodontist, 78, 502–509.

7. King, G.J. and Fischlschweiger, W. (1982) The effect of force magnitude on extractable bone resorptive activity and cemental cratering in orthodontic tooth movement. Journal of Dental Research, 61, 775–779.

8. Casa, M.A., Faltin, R.M., Faltin, K., Sander, F.G. and Arana-Chavez, V.E. (2001) Root resorptions in upper first premolars after application of continuous torque moment. Intra-individual study. Journal of Orofacial Orthopedics, 62, 285–295.

9. Chan, E.K., Petocz, P. and Darendeliler, M.A. (2005) Validation of two-dimensional measurements of root resorption craters on human premolars after 28 days of force application. European Journal of Orthodontics, 27, 390–395.

10. Darendeliler, M.A., Kharbanda, O.P., Chan, E.K.M., Srivicharnkul, P., Rex, T., Swain, M.V., Jones, A.S. and Petocz, P. (2004) Root resorption and its association with alterations in physical properties, mineral con-tents and resorption craters in human premolars following application of light and heavy controlled orthodontic forces. Orthodontics & Crani-ofacial Research, 7, 79–97.

11. Faltin, R.M., Faltin, K., Sander, F.G. and Arana-Chavez, V.E. (2001) Ultra-structure of cementum and periodontal ligament after continuous intru-sion in humans: a transmission electron microscopy study. European Jour-nal of Orthodontics, 23, 35–49.

12. Vardimon, A.D., Graber, T.M., Voss, L.R. and Lenke, J. (1991) Determi-nants controlling iatrogenic external root resorption and repair during and after palatal expansion. The Angle Orthodontist, 61, 113–122; dis-cussion 123.

13. Barbagallo, L.J., Jones, A.S., Petocz, P. and Darendeliler, M.A. (2008) Phys-ical properties of root cementum: Part 10. Comparison of the effects of invisible removable thermoplastic appliances with light and heavy ortho-dontic forces on premolar cementum. A microcomputed-tomography study. American Journal of Orthodontics and Dentofacial Orthopedics, 133, 218–227.

14. Cheng, L.L., Türk, T., Elekdağ-Türk, S., Jones, A.S., Petocz, P. and Daren-deliler, M.A. (2009) Physical properties of root cementum: Part 13. Repair of root resorption 4 and 8 weeks after the application of continuous light and heavy forces for 4 weeks: a microcomputed-tomography study. Amer-ican Journal of Orthodontics and Dentofacial Orthopedics. 136: 320.e1–320.e10; discussion 320.

15. Chan, E. and Darendeliler, M.A. (2005) Physical properties of root cemen-tum: Part 5. Volumetric analysis of root resorption craters after applica-


Dow



Hohenheim


tion of light and heavy orthodontic forces. American Journal of Ortho-dontics and Dentofacial Orthopedics, 127, 186–195.

16. Weltman, B., Vig, K.W., Fields, H.W., Shanker, S. and Kaizar, E.E. (2010) Root resorption associated with orthodontic tooth movement: a system-atic review. American Journal of Orthodontics and Dentofacial Orthope-dics, 137, 462–476; discussion 12A.

17. Owman-Moll, P., Kurol, J. and Lundgren, D. (1996) Effects of a doubled orthodontic force magnitude on tooth movement and root resorptions. An inter-individual study in adolescents. European Journal of Orthodontics, 18, 141–150.

18. Owman-Moll, P., Kurol, J. and Lundgren, D. (1996) The effects of a four-fold increased orthodontic force magnitude on tooth movement and root resorptions. An intra-individual study in adolescents. European Journal of Orthodontics, 18, 287–294.

19. Quinn, R.S. and Yoshikawa, D.K. (1985) A reassessment of force magni-tude in orthodontics. American Journal of Orthodontics, 88, 252–260.

20. Yee, J.A., Türk, T., Elekdağ-Türk, S., Cheng, L.L. and Darendeliler, M.A. (2009) Rate of tooth movement under heavy and light continuous ortho-dontic forces. American Journal of Orthodontics and Dentofacial Ortho-pedics, 136, 150.e1–150.e9; discussion 150.

21. Melsen, B. (1999) Biological reaction of alveolar bone to orthodontic tooth movement. The Angle Orthodontist, 69, 151–158.

22. Kiliç, N., Oktay, H. and Ersöz, M. (2010) Effects of force magnitude on tooth movement: an experimental study in rabbits. European Journal of Orthodontics, 32, 154–158.

23. Ren, Y., Maltha, J.C., Van ‘t Hof, M.A. and Kuijpers-Jagtman, A.M. (2004) Optimum force magnitude for orthodontic tooth movement: a mathematic model. American Journal of Orthodontics and Dentofacial Orthopedics, 125, 71–77.

24. Tomizuka, R., Kanetaka, H., Shimizu, Y., Suzuki, A., Igarashi, K. and Mitani, H. (2006) Effects of gradually increasing force generated by per-manent rare earth magnets for orthodontic tooth movement. The Angle Orthodontist, 76, 1004–1009.

25. Dellinger, E.L. (1986) A clinical assessment of the Active Vertical Correc-tor—a nonsurgical alternative for skeletal open bite treatment. American Journal of Orthodontics, 89, 428–436.

26. Vardimon, A.D., Graber, T.M., Voss, L.R. and Verrusio, E. (1987) Magnetic versus mechanical expansion with different force thresholds and points of force application. American Journal of Orthodontics and Dentofacial Orthopedics, 92, 455–466.

27. Darendeliler, M.A. and Friedli, J.M. (1994). Case report: treatment of an impacted canine with magnets. Journal of Clinical Orthodontics, 28, 639–643.

28. Sandler, J.P. (1991) An attractive solution to unerupted teeth. American Journal of Orthodontics and Dentofacial Orthopedics, 100, 489–493.

29. Darendeliler, M.A. and Joho, J.P. (1993) Magnetic activator device II (MAD II) for correction of Class II, division 1 malocclusions. American Journal of Orthodontics and Dentofacial Orthopedics, 103, 223–239.

30. Vardimon, A.D., Graber, T.M., Voss, L.R. and Muller, T.P. (1990) Functional orthopedic magnetic appliance (FOMA) III—modus operandi. American Journal of Orthodontics and Dentofacial Orthopedics, 97, 135–148.

31. Blechman, A.M. (1985) Magnetic force systems in orthodontics. Clinical results of a pilot study. American Journal of Orthodontics, 87, 201–210.

32. Bondemark, L. and Kurol, J. (1992) Distalization of maxillary first and second molars simultaneously with repelling magnets. European Journal of Orthodontics, 14, 264–272.

33. Gianelly, A.A., Vaitas, A.S., Thomas, W.M. and Berger, D.G. (1988) Distali-zation of molars with repelling magnets. Journal of Clinical Orthodontics: JCO, 22, 40–44.

34. Muller, M. (1984) The use of magnets in orthodontics: an alternative means to produce tooth movement. European Journal of Orthodontics, 6, 247–253.

35. Darendeliler, M.A. and Joho, J.P. (1992) Class II bimaxillary protrusion treated with magnetic forces. Journal of Clinical Orthodontics: JCO, 26, 361–368.

36. Kawata, T., Hirota, K., Sumitani, K., Umehara, K., Yano, K., Tzeng, H.J. and Tabuchi, T. (1987) A new orthodontic force system of magnetic brack-ets. American Journal of Orthodontics and Dentofacial Orthopedics, 92, 241–248.

37. Burstone, C.J. (1986) The biophysics of bone remodelling during ortho-dontics—optimal force considerations In: Norton, L.A., Burstone, C.J. (ed.), The Biology of Tooth Movement. CRC Press, Boca Raton, pp. 321–333.

38. Darvell, B.W. and Dias, A.P. (2006) Non-inverse-square force-distance law for long thin magnets. Dental Materials, 22, 909–918.

39. Darendeliler, M.A., Darendeliler, A. and Mandurino, M. (1997) Clinical application of magnets in orthodontics and biological implications: a review. European Journal of Orthodontics, 19, 431–442.

40. Noar, J.H. and Evans, R.D. (1999) Rare earth magnets in orthodontics: an overview. British Journal of Orthodontics, 26, 29–37.

41. Brudvik, P. and Rygh, P. (1993) The initial phase of orthodontic root resorption incident to local compression of the periodontal ligament. European Journal of Orthodontics, 15, 249–263.

42. Tomizuka, R., Shimizu, Y., Kanetaka, H., Suzuki, A., Urayama, S., Kikuchi, M., Mitani, H. and Igarashi, K. (2007) Histological evaluation of the effects of initially light and gradually increasing force on orthodontic tooth movement. The Angle Orthodontist, 77, 410–416.

43. Almeida, M.A., Phillips, C., Kula, K. and Tulloch, C. (1995) Stability of the palatal rugae as landmarks for analysis of dental casts. The Angle Ortho-dontist, 65, 43–48.

44. Bailey, L.T., Esmailnejad, A. and Almeida, M.A. (1996) Stability of the palatal rugae as landmarks for analysis of dental casts in extraction and nonextraction cases. The Angle Orthodontist, 66, 73–78.

45. Harris, D.A., Jones, A.S. and Darendeliler, M.A. (2006) Physical proper-ties of root cementum: part 8. Volumetric analysis of root resorption cra-ters after application of controlled intrusive light and heavy orthodontic forces: a microcomputed tomography scan study. American Journal of Orthodontics and Dentofacial Orthopedics, 130, 639–647.

46. Schwarz, A.M. (1932) Tissue changes incident to orthodontic tooth move-ment. International Journal of Orthodontics, 18, 331–352.

47. Paetyangkul, A., Turk, T., Elekdag-Turk, S., Jones, A.S., Petocz, P. and Darendeliler, M.A. (2009) Physical properties of root cementum: part 14. The amount of root resorption after force application for 12 weeks on maxillary and mandibular premolars: a microcomputed-tomography study. American Journal of Orthodontics and Dentofacial Orthopedics, 136, 492 e1–492.e9.

48. Samuels, R.H., Rudge, S.J. and Mair, L.H. (1998) A clinical study of space closure with nickel-titanium closed coil springs and an elastic module. Amer-ican Journal of Orthodontics and Dentofacial Orthopedics, 114, 73–79.

49. Gonzales, C., Hotokezaka, H., Arai, Y., Ninomiya, T., Tominaga, J., Jang, I., Hotokezaka, Y., Tanaka, M. and Yoshida, N. (2009) An in vivo 3D micro-CT evaluation of tooth movement after the application of different force magnitudes in rat molar. The Angle Orthodontist, 79, 703–714.

50. Van Leeuwen, E.J., Kuijpers-Jagtman, A.M., Von den Hoff, J.W., Wagener, F.A. and Maltha, J.C. (2010) Rate of orthodontic tooth movement after changing the force magnitude: an experimental study in beagle dogs. Orthodontics & Craniofacial Research, 13, 238–245.

51. Sameshima, G.T. and Sinclair, P.M. (2001) Predicting and preventing root resorption: Part I. Diagnostic factors. American Journal of Orthodontics and Dentofacial Orthopedics, 119, 505–510.

52. Blake, M., Woodside, D.G. and Pharoah, M.J. (1995) A radiographic comparison of apical root resorption after orthodontic treatment with the edgewise and Speed appliances. American Journal of Orthodontics and Dentofacial Orthopedics, 108, 76–84.

53. Apajalahti, S. and Peltola, J.S. (2007) Apical root resorption after ortho-dontic treatment—a retrospective study. European Journal of Orthodon-tics, 29, 408–412.

54. Lund, H., Gröndahl, K., Hansen, K. and Gröndahl, H.G. (2012) Apical root resorption during orthodontic treatment. A prospective study using cone beam CT. The Angle Orthodontist, 82, 480–487.


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