Biomechanical aspects of external root resorption in orthodontic therapy.

Med Oral Patol Oral Cir Bucal. 2007 Dec;12(8):E610-3

Authors: Abuabara A

External apical root resorption is a common phenomenon associated with orthodontic treatment. The factors relevant to root resorption can be divided into biological and mechanical factors. Some mechanical and biological factors might be associated with an increased or decreased risk of root resorption during orthodontic treatment. For mechanical factors, the extensive tooth movement, root torque and intrusive forces, movement type, orthodontic force magnitude, duration and type of force are involved. For biological factors, a genetic susceptibility, systemic disease, gender and medication intake have been demonstrated influence root resorption. Orthodontic therapy of patients with increased risk of root resorption should be carefully planned. Medical history, medication intake, family history, tooth agenesis, root morphology, oral health and habits must be considerate if we do not want jeopardize our patients by severe root resorption. To monitor apical root resorption the standard procedure is a radiographic examination after 6 months of treatment. In teeth with enhanced risk, a 3-month radiographic follow-up is recommended. The administration of anti-inflammatory drugs might suppress root resorption induced by orthodontic therapy, although none study was enough conclusive to indicate a protocol for patients with enhanced risk. In the event of multiple external root resorption, the diagnostic procedure should focus on the exclusion of the local factors and its associations (such as magnitude, duration and type of orthodontic force; periodontal disease; root form) that might lead to external root resorption. Systemic disorders associated with phosphorus-calcium metabolic alterations shall be suspected. This review searched the current knowledge of the mechanical and biological aspects of root resorption in orthodontic tooth movement.

PMID: 18059250 [PubMed - in process]

Initial pulp changes during orthodontic movement: histomorphological evaluation.

Braz Dent J. 2007;18(1):34-9

Authors: Santamaria M, Milagres D, Iyomasa MM, Stuani MB, Ruellas AC

This study evaluated pulp changes in molars of rats submitted to tooth movement by application of a 0.4 N force. Twenty-five adult male Wistar rats (Rattus norvegicus, albinus) were randomly assigned to 5 groups (n=5), being one control group not submitted to force application, and four study groups of 6, 12, 24 and 72 h of force application. The study groups received a 5-mm long nickel-titanium closed coil spring, placed from the right maxillary first molar to the maxillary incisors of each animal. The coil spring was used for mesial inclination of the first molar. After the specific period of tooth movement of each study group, the animals were sacrificed and specimens containing the teeth submitted to movement were processed and stained with hematoxylin and eosin for histological analysis under light microscopy. The results demonstrated alteration of the odontoblastic layer, with hypertrophy of odontoblasts especially at the mesial area of the coronal pulp, edema of the pulp connective tissue in the central area of the pulp, and vascular alteration with accumulation of erythrocytes and leukocytes inside the vessels, especially at the mesial root of the moved teeth. These changes were less remarkable for the 72-h period. Thus, it may be concluded that tooth movement yielded pulpal tissue alterations compatible with an inflammatory process, which are reversible if the aggression is not more intense than the physiological limit of tissue tolerance.

PMID: 17639198 [PubMed - indexed for MEDLINE]

Alpha11 beta1 integrin-dependent regulation of periodontal ligament function in the erupting mouse incisor.

Mol Cell Biol. 2007 Jun;27(12):4306-16

Authors: Popova SN, Barczyk M, Tiger CF, Beertsen W, Zigrino P, Aszodi A, Miosge N, Forsberg E, Gullberg D

The fibroblast integrin alpha11beta1 is a key receptor for fibrillar collagens. To study the potential function of alpha11 in vivo, we generated a null allele of the alpha11 gene. Integrin alpha11(-/-) mice are viable and fertile but display dwarfism with increased mortality, most probably due to severely defective incisors. Mutant incisors are characterized by disorganized periodontal ligaments, whereas molar ligaments appear normal. The primary defect in the incisor ligament leads to halted tooth eruption. alpha11beta1-defective embryonic fibroblasts displayed severe defects in vitro, characterized by (i) greatly reduced cell adhesion and spreading on collagen I, (ii) reduced ability to retract collagen lattices, and (iii) reduced cell proliferation. Analysis of matrix metalloproteinase in vitro and in vivo revealed disturbed MMP13 and MMP14 synthesis in alpha11(-/-) cells. We show that alpha11beta1 is the major receptor for collagen I on mouse embryonic fibroblasts and suggest that alpha11beta1 integrin is specifically required on periodontal ligament fibroblasts for cell migration and collagen reorganization to help generate the forces needed for axial tooth movement. Our data show a unique role for alpha11beta1 integrin during tooth eruption.

PMID: 17420280 [PubMed - indexed for MEDLINE]

[Effects of rh-GH on the remodeling of periodontium in the ovariectomized rats after orthodontic tooth movement]

Shanghai Kou Qiang Yi Xue. 2006 Oct;15(5):521-5

Authors: Zhang J, Wang SL, Wang XX, Huang Y, Zhang WJ

PURPOSE: To investigate the effects of the recombinant human growth hormone (rh-GH) on the periodontal cells in the ovariectomized rats after orthodontic tooth movement. METHODS: Thirty seven-week-old SPF female Wistar rats were randomly divided into three groups: the control group, the ovariectomy-saline group (OVX-NS group) and the variectomy-GH group(OVX-GH group). Different treatments, including variectomy and injecting normal saline solution, were adminstrated on the rats of the three groups. The number of osteoclast in the compressed alveolar bone was counted on the fifteenth and thirtieth days. Histological changes were observed. The data was analyzed with ANOVA by SPSS12.0 software package. RESULTS: By ANOVA analysis, there were significant differences in the number of osteoclast between the three groups in the same period. The number of osteoclast in the compressed alveolar bone of OVX-NS group was significantly more than that of the OVX-GH group (P < 0.05), and that of the control group was the least. In the same group, there wasn't significant difference between the rats killed 15 days later and 30 days later (P > 0.05). The trauma and inflammation of periodontal membrane of OVX-GH group had been significantly improved compared with the OVX-NS group. CONCLUSION: It is suggested that injecting rh-GH can decrease the number of osteoclast in the compressed alveolar bone in the adult rats after orthodontic tooth movement. At the same time, it can improve the recovery of pathologic changes of periodontal tissue caused by the orthodontic force. There will be a synergetic effect between adult orthodontic treatment and rh-GH.

PMID: 17348229 [PubMed - in process]

Morphohistological change and expression of HSP70, osteopontin and osteocalcin mRNAs in rat dental pulp cells with orthodontic tooth movement.

Bull Tokyo Dent Coll. 2006 Aug;47(3):117-24

Authors: Shigehara S, Matsuzaka K, Inoue T

Morphological change and expression of osteopontin, osteocalcin, and HSP70 mRNAs in rat dental pulp cells with experimental orthodontic tooth movement were investigated. Elastic rubber blocks, 0.65 mm in thickness, were inserted between the maxillary first and second molars in rats. In addition to morphological observations of HE staining and TUNEL staining at days 3, 7, 14 and 28 after insertion of elastic rubber blocks, expression of HSP70, osteopontin and osteocalcin mRNAs was also analyzed using quantitative RT-PCR with a LightCycler. Morphologically, proliferation and vasodilation of capillaries was evident in the pulp at days 3 and 7, and a sparse odontoblast layer and apoptosis in the pulp were observed at days 7 and 14 after rubber block insertion. Expression of HSP70, osteopontin and osteocalcin mRNAs in the experimental groups was higher than that in the control group at all time points. This suggests that orthodontic tooth movement causes degenerative changes and apoptosis in pulp cells, while pulp homeostasis is maintained at the genetic level.

PMID: 17344619 [PubMed - indexed for MEDLINE]

Root resorption and orthodontic treatment. Review of the literature.

Minerva Stomatol. 2007 Jan-Feb;56(1-2):31-44

Authors: Pizzo G, Licata ME, Guiglia R, Giuliana G

The aim of this paper was to provide a systematic review of the literature on the root resorption caused by orthodontic treatment. Original papers on this subject, published in English from January 2000 until December 2005, were located in the MEDLINE/PubMed database. Other sources were taken from the references of the selected papers. Root resorption is the most common sequela of the orthodontic treatment. It is an inflammatory process that leads to an ischemic necrosis localized in the periodontal ligament when the orthodontic force is applied. The onset and progression of root resorption are associated with risk factors related to the orthodontic treatment such as the duration of treatment, the magnitude of the force applied, the direction of the tooth movement, the method of force application (continuous versus intermittent), the orthodontic movement. Patient-related risk factors are the individual susceptibility on a genetic basis, some systemic diseases, anomalies in root morphology, dental trauma, and previous endodontic treatment. The prevention of root resorption during the orthodontic treatment may be performed controlling the risk factors. The periodic radiographic control during the treatment is necessary in order to detect the occurrence of root damages and quickly reassess the treatment goals.

PMID: 17287705 [PubMed - indexed for MEDLINE]

The spectrum of Apert syndrome: phenotype, particularities in orthodontic treatment, and characteristics of orthognathic surgery.

Head Face Med. 2007;3:10

Authors: Hohoff A, Joos U, Meyer U, Ehmer U, Stamm T

In the PubMed accessible literature, information on the characteristics of interdisciplinary orthodontic and surgical treatment of patients with Apert syndrome is rare. The aim of the present article is threefold: (1) to show the spectrum of the phenotype, in order (2) to elucidate the scope of hindrances to orthodontic treatment, and (3) to demonstrate the problems of surgery and interdisciplinary approach.Children and adolescents who were born in 1985 or later, who were diagnosed with Apert syndrome, and who sought consultation or treatment at the Departments of Orthodontics or Craniomaxillofacial Surgery at the Dental School of the University Hospital of M&#xFC;nster (n = 22; 9 male, 13 female) were screened. Exemplarily, three of these patients (2 male, 1 female), seeking interdisciplinary (both orthodontic and surgical treatment) are presented. Orthodontic treatment before surgery was performed by one experienced orthodontist (AH), and orthognathic surgery was performed by one experienced surgeon (UJ), who diagnosed the syndrome according to the criteria listed in OMIM. In the sagittal plane, the patients suffered from a mild to a very severe Angle Class III malocclusion, which was sometimes compensated by the inclination of the lower incisors; in the vertical dimension from an open bite; and transversally from a single tooth in crossbite to a circular crossbite. All patients showed dentitio tarda, some impaction, partial eruption, idopathic root resorption, transposition or other aberrations in the position of the tooth germs, and severe crowding, with sometimes parallel molar tooth buds in each quarter of the upper jaw.Because of the severity of malocclusion, orthodontic treatment needed to be performed with fixed appliances, and mainly with superelastic wires. The therapy was hampered with respect to positioning of bands and brackets because of incomplete tooth eruption, dense gingiva, and mucopolysaccharide ridges. Some teeth did not move, or moved insufficiently (especially with respect to rotations and torque) irrespective of surgical procedures or orthodontic mechanics and materials applied, and without prognostic factors indicating these problems. Establishing occlusal contact of all teeth was difficult. Tooth movement was generally retarded, increasing the duration of orthodontic treatment. Planning of extractions was different from that of patients without this syndrome.In one patient, the sole surgical procedure after orthodontic treatment with fixed appliances in the maxilla and mandible was a genioplasty. Most patients needed two- jaw surgery (bilateral sagittal split osteotomy [BSSO] with mandibular setback and distraction in the maxilla). During the period of distraction, the orthodontist guided the maxilla into final position by means of bite planes and intermaxillary elastics.To our knowledge, this is the first article in the PubMed accessible literature describing the problems with respect to interdisciplinary orthodontic and surgical procedures. Although the treatment results are not perfect, patients undergoing these procedures benefit esthetically to a high degree.Patients need to be informed with respect to the different kinds of extractions that need to be performed, the increased treatment time, and the results, which may be reached using realistic expectations.

PMID: 17286873 [PubMed]

MEPE expression in osteocytes during orthodontic tooth movement.

Arch Oral Biol. 2007 Jul;52(7):684-90

Authors: Gluhak-Heinrich J, Pavlin D, Yang W, MacDougall M, Harris SE

MEPE and DMP1 may play a role in mineralisation and demineralisation within the osteocyte microenvironment. Our earlier studies showed that DMP1 is mechanically responsive [Gluhak-Heinrich J, Ye L, Bonewald LF, Feng JQ, MacDougall M, Harris SE, et al. Mechanical loading stimulates dentin matrix protein 1 (DMP1) in osteocytes in vivo. J Bone Min Res 2003;18(5):807-17]. OBJECTIVES: To examine the effect of mechanical loading on the expression of MEPE using mouse tooth movement model, and compare this effect to that on DMP1. METHODS: In situ hybridisation and immunohistochemistry was performed on 38 treated and 38 control bone sites loaded 6-72 h. ImageJ was used for quantification of mRNA expression in osteocytes. RESULTS: Alveolar osteocytes showed high basal level of MEPE that decreased during the first day of loading, followed by 2.8-fold stimulation at day 3, and returning to a control level by day 7. CONCLUSION: The osteocyte specific mechanical stimulation of MEPE was delayed and different, compared to that of DMP1. This suggests a distinct role of MEPE and DMP1 in the response of osteocytes to mechanical loading in vivo.

PMID: 17270144 [PubMed - indexed for MEDLINE]

Magnitude and reproducibility of forces generated by clinicians during laceback placement.

J Orthod. 2006 Dec;33(4):270-5; discussion 256

Authors: Khambay BS, McHugh S, Millett DT

OBJECTIVE: To determine the magnitude and reproducibility of forces generated by clinicians during laceback placement using a force-measuring typodont. SETTING: An in vitro investigation. MATERIALS AND METHODS: An in vitro typodont model was developed, which incorporated strain gauges attached to a personal computer to allow measurement of the force generated on application of lacebacks. Ten operators were instructed to place lacebacks five times, on two separate occasions (T1 and T2). Inter-operator and intra-operator forces produced at T1 and T2 were compared. MAIN OUTCOME MEASURES: Forces generated by laceback placement. RESULTS: The forces generated by clinicians ranged from 0 to 11.1 N. There were significant differences in the mean forces generated by the different operators (P < 0.001), with differences between time points not being consistent across all operators (P < 0.001). Some operators were more consistent than others in the forces generated. CONCLUSION: In vitro, there was a large inter-operator variation in the forces produced during laceback placement. With the in vitro model used in this study, few operators applied similar forces when placing lacebacks on two separate occasions.

PMID: 17142333 [PubMed - indexed for MEDLINE]

Osteoclast distribution within the rat interdental septum coincident to experimental tooth movement using light forces.

Anat Rec A Discov Mol Cell Evol Biol. 2006 Nov 30;

Authors: Johnson RB

There is little quantitative information concerning the number and distribution of bone-matrix resorbing osteoclasts (BMRO) within the adjacent alveolar bone coincident to tooth movement. We moved the right first maxillary molar tooth anteriorly in 40 female rats (E), the left side was untreated, serving as an internal control (IC). Forty female age and weight matched rats were untreated, serving as external controls (EC). BMRO were identified on periosteal and endosteal surfaces of the interdental septum from 1-5 days after initial force application using the MTB-322 antibody. The number of BMRO at periosteal surfaces of E was greater in IC and EC from 2-5 days (P < 0.001). Similarly, the number of BMRO at endosteal surfaces was greater from 1-5 days (P < 0.001). The number of BMRO at periosteal and endosteal surfaces was greater within E than within EC from 1-5 days (P < 0.001). Outcome data from IC were often significantly different from EC. Our data suggest that relatively low forces increase the number of BMRO, which are not uniformly distributed onto both periosteal and endosteal surfaces. Thus, the interdental septum resorbs at the alveolar wall and within spaces between the trabeculae, which, taken together, results in net removal of bone from areas of compression. These data also suggest that experimental tooth movement produces significant differences in the number and distribution of BMRO within IC and EC. Thus, EC groups should be included in studies of tooth movement. Anat Rec Part A 2006. (c) 2006 Wiley-Liss, Inc.

PMID: 17139673 [PubMed - as supplied by publisher]

Influence of alveolar support on stress in periodontal structures.

J Dent Res. 2006 Dec;85(12):1087-91

Authors: Ona M, Wakabayashi N

The influence of alveolar bone support on the functional capability of a tooth remains unclear. It was hypothesized that a reduction in alveolar support causes an increase of maximum stress in the periodontal structures. Mathematical models of the maxillary incisor to simulate in vivo tooth movement were constructed with periodontium of normal or reduced bone height, and normal or widened periodontal ligament (PDL) space. Under simulated bite force, the maximum tensile stress at the lingual cervical region in the PDL increased with bone height reduction, but decreased with PDL widening. The compressive stress at the cervical region in the cortical bone was no more than 22% of the yield strength of bone, and did not increase by the height reduction with widened PDL. The result suggests that the height reduction potentially causes mechanical damage to the PDL, but, of itself, is not likely to have a negative effect on the bone.

PMID: 17122159 [PubMed - indexed for MEDLINE]

Biomechanical behaviour of the periodontal ligament of the beagle dog during the first 5 hours of orthodontic force application.

Eur J Orthod. 2006 Dec;28(6):547-52

Authors: J&#xF3;nsdóttir SH, Giesen EB, Maltha JC

The aim of this study was to describe the mechanical behaviour of the periodontal ligament (PDL) in response to loading with different forces for a period of 5 hours. Seven young adult male beagle dogs (age 1.0-1.5 years) were used. After extractions and placement of implants, custom-made appliances on both sides of the mandible were used to measure the displacement of the second premolars. Tooth displacement was measured during 5 hours of force application. Each dog underwent two measurement sessions. One premolar was moved with a force of 100 cN in the first session and with 50 cN in the second. The contralateral premolar was moved with forces of 100 and 300 cN, respectively. Time-displacement curves showed a rapid instantaneous response lasting only a few seconds followed by a slowly decreasing creep displacement. The instantaneous response demonstrated a large individual variability, caused by both a dog and a force effect. Differences in tooth and PDL anatomy and in the orientation of the periodontal fibres are probably important in this respect. The individual variability faded after the first seconds of tooth displacement, when the viscoelastic properties of the periodontal fibres became more pronounced. The force effect was non-linear for the first minute. Higher forces did not lead to proportionally larger displacements. The non-linearity decreased in the second response. The PDL is a complex material that might be considered as a non-linear fibre-reinforced poroviscoelastic material.

PMID: 17101705 [PubMed - indexed for MEDLINE]

Biological markers for evaluation of root resorption.

Arch Oral Biol. 2007 Mar;52(3):203-8

Authors: Balducci L, Ramachandran A, Hao J, Narayanan K, Evans C, George A

BACKGROUND: External apical root resorption is a pathologic consequence of orthodontic tooth movement. Cementum and dentin are removed from the root surface while active force is present. OBJECTIVE: The aim of this study was to identify and quantify extracellular matrix proteins, dentin matrix protein 1 (DMP1), dentin phosphophoryn (PP), and dentin sialoprotein (DSP) in the gingival crevicular fluid (GCF) of subjects undergoing orthodontic treatment. METHODS: Subjects with mild (less than 2mm) and severe (more than 2mm) root resorption during orthodontic treatment were identified by radiographs. A control group of subjects with neither signs of root loss nor undergoing orthodontic treatment was also identified. GCF was collected from the upper incisors by using filter paper strips (Periopaper). The absorbed GCF was eluted and the proteins were separated by SDS-PAGE analysis and stained. Western blot and ELISA were also performed. One-way ANOVA and Scheff&#xE9; test were used for statistical analysis. RESULTS: SDS-PAGE analysis identified proteins at 77, 66, 55, 50 and 26kDa. Immunoblotting did not show any differential expression pattern between control and study groups. ELISA results revealed a significant difference in the concentrations of DMP1, PP and DSP between control and root resorption groups. Concentration of PP and DSP in severe root resorption group was also statistically higher than in mild root resorption group. CONCLUSION: DSP and PP could be suitable biological markers for monitoring root resorption during orthodontic treatment, since a significant difference in the level of these dentin specific proteins is detected in all groups.

PMID: 17097600 [PubMed - indexed for MEDLINE]

Which orthodontic archwire sequence? A randomized clinical trial.

Eur J Orthod. 2006 Dec;28(6):561-6

Authors: Mandall N, Lowe C, Worthington H, Sandler J, Derwent S, Abdi-Oskouei M, Ward S

The aim of this study was to compare three orthodontic archwire sequences. One hundred and fifty-four 10- to 17-year-old patients were treated in three centres and randomly allocated to one of three groups: A = 0.016-inch nickel titanium (NiTi), 0.018 x 0.025-inch NiTi, and 0.019 x 0.025-inch stainless steel (SS); B = 0.016-inch NiTi, 0.016-inch SS, 0.020-inch SS, and 0.019 x 0.025-inch SS; and C = 0.016 x 0.022-inch copper (Cu) NiTi, 0.019 x 0.025-inch CuNiTi, and 0.019 x 0.025-inch SS. At each archwire change and for each arch, the patients completed discomfort scores on a seven-point Likert scale at 4 hours, 24 hours, 3 days, and 1 week. Time in days and the number of visits taken to reach a 0.019 x 0.025-inch SS working archwires were calculated. A periapical radiograph of the upper left central incisor was taken at the start of the treatment and after placement of the 0.019 x 0.025-inch SS wire so root resorption could be assessed. There were no statistically significant differences between archwire sequences A, B, or C for patient discomfort (P > 0.05) or root resorption (P = 0.58). The number of visits required to reach the working archwire was greater for sequence B than for A (P = 0.012) but this could not be explained by the increased number of archwires used in sequence B.

PMID: 17041083 [PubMed - indexed for MEDLINE]

Fluid shear stress inhibits TNFalpha-induced osteocyte apoptosis.

J Dent Res. 2006 Oct;85(10):905-9

Authors: Tan SD, Kuijpers-Jagtman AM, Semeins CM, Bronckers AL, Maltha JC, Von den Hoff JW, Everts V, Klein-Nulend J

Bone tissue can adapt to orthodontic load. Mechanosensing in bone is primarily a task for the osteocytes, which translate the canalicular flow resulting from bone loading into osteoclast and osteoblast recruiting signals. Apoptotic osteocytes attract osteoclasts, and inhibition of osteocyte apoptosis can therefore affect bone remodeling. Since TNF-alpha is a pro-inflammatory cytokine with apoptotic potency, and elevated levels are found in the gingival sulcus during orthodontic tooth movement, we investigated if mechanical loading by pulsating fluid flow affects TNF-alpha-induced apoptosis in chicken osteocytes, osteoblasts, and periosteal fibroblasts. During fluid stasis, TNF-alpha increased apoptosis by more than two-fold in both osteocytes and osteoblasts, but not in periosteal fibroblasts. One-hour pulsating fluid flow (0.70 +/- 0.30 Pa, 5 Hz) inhibited (-25%) TNF-alpha-induced apoptosis in osteocytes, but not in osteoblasts or periosteal fibroblasts, suggesting a key regulatory role for osteocyte apoptosis in bone remodeling after the application of an orthodontic load.

PMID: 16998129 [PubMed - indexed for MEDLINE]

Segmental alveolar distraction for the correction of unilateral open-bite caused by multiple ankylosed teeth: A case report.

J Orthod. 2006 Sep;33(3):153-9

Authors: Susami T, Matsuzaki M, Ogihara Y, Sakiyama M, Takato T, Sugawara Y, Matsumoto S

Ankylosed teeth fail to erupt to meet their counterparts in the opposite jaw. In cases where ankylosis occurs in multiple teeth, the occlusion shows an open bite. This article describes a case of unilateral open bite caused by multiple ankylosed teeth, where treatment involved segmental alveolar bone distraction. A 25-year-old female patient presented with a left-sided unilateral open bite. On the left-hand side, only the lower incisors were not ankylosed. On the right, the maxillary first molar was ankylosed. All these ankylosed teeth were positioned below the occlusal plane. Her mother and brother also had multiple ankylosed teeth, and a familial cause was considered. Orthodontic tooth movement was considered impossible and segmental osteotomy on the left maxillary alveolar bone and downward bone distraction were performed as an alternative. A distractor consisting of orthodontic bands, wires and screws was devised and worn in the left mandibular dentition. Multi-bracket orthodontic appliances were also used for distraction. The amount of vertical movement was 7 mm at the premolar region. Five months after distraction, the multibracket appliance was removed, and fixed and removable retainers were placed. Eight months after distraction, prosthodontic restorations on the occlusal surfaces of the ankylosed teeth were made to obtain the final occlusion. The unilateral open bite was successfully treated and a good occlusion was obtained. The occlusion has shown good long-term stability for more than 3 years.

PMID: 16926308 [PubMed - in process]

Initial changes of centres of rotation of the anterior segment in response to horizontal forces.

Eur J Orthod. 2006 Oct;28(5):471-4

Authors: Choy K, Kim KH, Burstone CJ

This study investigated the changes in the initial centres of rotation (Crot) of the upper six anterior teeth in response to a horizontal load. Six upper anterior teeth were extracted, splinted as a unit, and embedded in dental stone after the roots were uniformly coated with silicone. An aluminium fixture was bonded to the anterior segment and three linear variable differential transformers (LVDTs) were attached to measure the microdisplacement of the segment. A pulley and dead weight assembly were used to apply a 200 g occluso-gingivally varying horizontal force to the segment. The changes in the Crot for the anterior segment to the horizontal load were recorded. The results showed that the centre of resistance (Cres) of the upper anterior segment was located 14.5 mm apical and 9.5 mm distal from the incisal edge of the central incisors. A linear functional axis (a trace of the measured Crot) was recorded. The functional axis maintained an angle of 14.5 degrees to the vertical axis of the anterior segment passing through the Cres of the segment. The Crot constant, which determines the tipping sensitivity of the segment, was 23 mm(2). The results demonstrate that the upper anterior segment may be slightly intruded when a horizontal force is applied and is less prone to tipping than a single tooth.

PMID: 16916900 [PubMed - indexed for MEDLINE]

A modified double pedicle graft technique and other mucogingival interceptive surgeries for the management of impacted teeth: a case series.

Indian J Dent Res. 2006 Jan-Mar;17(1):35-9

Authors: Sunil S, Avinash BS, Prasad D, Jagadish L

Maxillary canine is one of the most common teeth that are impacted. This accounts for 1-2% of all patients who attend orthodontic treatment. The key to achieve maximal eruption of these teeth is their surgical exposure and the role of periodontist in such situations is to provide a functional and satisfactory width of attached gingiva on the labial surface. There are different techniques to surgically expose the impacted teeth, namely--gingivectomy technique, apically positioned flap, closed eruption technique, modified apically positioned flap, double pedicle flap and free gingival graft. Selection of the procedure is dependent on the positioning of the tooth in relation to mucogingival junction and attached gingiva. In the present case series we describe three different techniques for uncovering of impacted teeth, which are apically positioned flap, closed eruption technique and a modified double pedicle graft specially planned for the situation. These procedures when selected diligently using sound selection criteria will create adequate width of attached gingiva which minimizes or eliminates the future mucogingival problems.

PMID: 16900893 [PubMed - indexed for MEDLINE]

Clodronate inhibits PGE(2) production in compressed periodontal ligament cells.

J Dent Res. 2006 Aug;85(8):757-60

Authors: Liu L, Igarashi K, Kanzaki H, Chiba M, Shinoda H, Mitani H

Periodontal ligament (PDL) cells play an essential role in orthodontic tooth movement. We recently reported that clodronate, a non-N-containing bisphosphonate, strongly inhibited tooth movement in rats, and thus could be a useful adjunct for orthodontic treatment. However, it is not clear how clodronate affects the responses of PDL cells to orthodontic force. In this study, we hypothesized that clodronate prevents the mechanical stress-induced production of prostaglandin E(2) (PGE(2)), interleukin-1beta (IL-1beta), and nitric oxide (NO) in human PDL cells. A compressive stimulus caused a striking increase in PGE(2) production, while the responses of IL-1beta and NO were less marked. Clodronate concentration-dependently inhibited the stress-induced production of PGE(2). Clodronate also strongly inhibited stress-induced gene expression for COX-2 and RANKL. These results suggest that the inhibitory effects of clodronate on tooth movement and osteoclasts may be due, at least in part, to the inhibition of COX-2-dependent PGE(2) production and RANKL expression in PDL cells.

PMID: 16861295 [PubMed - indexed for MEDLINE]

RANKL increase in compressed periodontal ligament cells from root resorption.

J Dent Res. 2006 Aug;85(8):751-6

Authors: Yamaguchi M, Aihara N, Kojima T, Kasai K

The ligand receptor activator of NFkappaB (RANKL) plays an important role in osteoclast formation. However, very little is known about the relationship between external apical root resorption during orthodontic treatment and RANKL. We hypothesized that compressive force is responsible for RANKL formation and up-regulation of osteoclastogenesis in periodontal ligament (PDL) cells from patients with severe orthodontically induced external apical root resorption. RANKL and osteoprotegerin (OPG) production, TRAP-positive cells, and resorptive pits were determined. The increase of RANKL and the decrease of OPG were greater in the severe root resorption group than in the non-resorption group. The numbers of TRAP-positive cells and resorptive pits were also increased in the severe root resorption group than in the non-resorption group. These results support the hypothesis that the compressed PDL cells obtained from tissues with severe external apical root resorption may produce a large amount of RANKL and up-regulate osteoclastogenesis.

PMID: 16861294 [PubMed - indexed for MEDLINE]

Surgical and orthodontic treatment of an impacted permanent central incisor: a case report.

J Indian Soc Pedod Prev Dent. 2006 Jun;24(2):100-3

Authors: Thosar NR, Vibhute P

Although impaction of a permanent tooth is rarely diagnosed during the mixed dentition period, an impacted central incisor is usually diagnosed accurately when there is delay in the eruption of tooth. In this article, the impacted incisor was moved into it's proper position with surgical exposure and orthodontic traction, after which it showed good stability.

PMID: 16823236 [PubMed - indexed for MEDLINE]

Increase of galanin in trigeminal ganglion during tooth movement.

J Dent Res. 2006 Jul;85(7):658-63

Authors: Deguchi T, Yabuuchi T, Ando R, Ichikawa H, Sugimoto T, Takano-Yamamoto T

It is known that nerve fibers containing neuropeptides such as galanin increase in the periodontal ligament during experimental tooth movement. However, the origin of galanin-containing nerve fibers in the periodontal ligament remains unclear. This study was conducted to examine our hypothesis that the increased galanin nerve fibers have a sensory neuronal origin, and that the peptide is associated with pain transmission and/or periodontal ligament remodeling during experimental tooth movement. In control rats, galanin-immunoreactive trigeminal ganglion cells were very rare and were observed predominantly in small ganglion cells. After 3 days of experimental tooth movement, galanin-immunoreactive trigeminal ganglion cells significantly increased, and the most marked increase was observed at 5 days after experimental tooth movement. Furthermore, their cell size spectrum also significantly changed after 3 and 5 days of movement: Medium-sized and large trigeminal ganglion cells began expressing, and continued to express, galanin until 14 days after experimental tooth movement. These findings suggest that the increase of galanin in the periodontal ligament during experimental tooth movement at least partially originates from trigeminal ganglion neurons and may play a role in pain transmission and/or periodontal remodeling.

PMID: 16798869 [PubMed - indexed for MEDLINE]

Is mild dental invagination a risk factor for apical root resorption in orthodontic patients?

Eur J Orthod. 2006 Aug;28(4):307-12

Authors: Mavragani M, Apisariyakul J, Brudvik P, Selvig KA

The purpose of this retrospective study was to assess if dental invagination is a risk factor for root resorption during orthodontic treatment. The sample consisted of 91 patients (32 males, 59 females) with a mean age of 13.1 years (range 9.3-32.1 years) with complete orthodontic records, including periapical radiographs of the maxillary incisors before and after treatment. Forty-nine patients had at least one maxillary incisor invaginated, whilst the remaining 42 patients were free of dental invaginations. Variables recorded for each patient included gender, age, Angle classification, extraction or non-extraction therapy, ANB angle, overjet, overbite, trauma, habits, agenesis, tooth exfoliation, treatment duration, Class II elastics, body-build, general factors, impacted canines, and root form deviation. Crown and root length of the maxillary incisors were measured on pre- and post-treatment long cone periapical radiographs corrected for image distortion. The percentage of root shortening and root length loss in millimetres was then calculated. Most of the invaginated teeth were minor type 1. Statistical analysis revealed no significant difference in the severity of apical root resorption between invaginated and non-invaginated incisors in patients without dental invaginations, nor was the extent of dental invagination related to the severity of apical root resorption. However, invaginated teeth had malformed roots more often than non-invaginated teeth. Dental invagination, and particularly type 1, cannot be considered a risk factor for apical root resorption during orthodontic tooth movement.

PMID: 16763089 [PubMed - indexed for MEDLINE]

Correction of anterior open bite in a case of achondroplasia.

Indian J Dent Res. 2005 Oct-Dec;16(4):159-66

Authors: Karpagam S, Rabin K, George M, Santhosh K

Treatment planning for patients with skeletal deformities is often considered challenging. This article reports a female patient with achondroplasia who presented with severe maxillary retrognathism and vertical excess along with anterior open bite. The clinical and cephalometric findings of the patient are detailed here. The treatment plan consisted of modified anterior maxillary osteotomy for simultaneous vertical and sagittal augmentation along with orthodontic intervention. The course of surgical-orthodontic treatment and the results are presented. This treatment is to be followed by correction of vertical maxillary excess after completion of growth. This paper concludes that the dentoalveolar component of a skeletal deformity can be handled independent of the craniofacial management.

PMID: 16761710 [PubMed - indexed for MEDLINE]

Comparative 35S-sulfate and 3H-proline metabolism within the interdental septal bone and adjacent periodontal ligament.

Anat Rec A Discov Mol Cell Evol Biol. 2006 Jul;288(7):817-26

Authors: Johnson RB

Tooth movements require rapid remodeling of the periodontal ligament (PDL) and adjacent alveolar bone. Our objective was to compare the regional metabolism of sulfated-glycosaminoglycans (sGAG) within the PDL and adjacent alveolar bone and compare it to the metabolism of collagenous proteins using radioautographic techniques. Rats were injected with either (3)H-proline or (35)S-sulfate and maxillae were removed at 1, 6, and 12 hr 1-7 days later. Silver grains were counted over the PDL and adjacent alveolar bone and the incorporation and removal rates for each radioisotope were determined. In general, net collagenous protein incorporation and removal were greatest within the distal and net sGAG incorporation and removal were greatest within the mesial compartments of the periodontium. The rate of removal of (3)H-proline was significantly greater within the distal alveolar bone surface than the adjacent PDL at all levels (P < 0.001). In contrast, the rate of removal of (35)S-sulfate was significantly greater in the PDL than within the adjacent mesial surface of the interdental septum at all levels (P < 0.001). The mesial surfaces of the interdental septum had a slower rate of removal of both isotopes than distal surfaces at all levels (P < 0.001). Our data suggest significant regional differences in the metabolism of (35)S-sulfate and (3)H-proline within the PDL and alveolar bone, which likely result from the characteristics of the forces produced by the adjacent teeth and may be a factor in the remodeling of the alveolar wall coincident to tooth movement.

PMID: 16761288 [PubMed - indexed for MEDLINE]

The tissue, cellular, and molecular regulation of orthodontic tooth movement: 100 years after Carl Sandstedt.

Eur J Orthod. 2006 Jun;28(3):221-40

Authors: Meikle MC

The first experimental investigation of orthodontic tooth movement was published by Sandstedt in 1904-1905. After 100 years, there is a good understanding of the sequence of events at both tissue and cellular levels and now the current focus of research is at the molecular level. The techniques of reverse transcription-polymerase chain reaction and in situ hybridization to detect mRNAs of interest have revolutionized tooth movement studies and an expanding list of antibodies and enzyme-linked immunosorbent assays directed against human and animal proteins will facilitate their identification in tissue sections and/or culture supernatants. Nevertheless, although this technology has greatly simplified research for the clinical and laboratory investigator, message is not always translated into protein, and the presence of a protein does not necessarily mean it is biologically active. In vivo and in vitro methods have been widely used in tooth movement studies. However, data from in vitro models, in which the mechanical stimulus can be carefully controlled (tension versus compression; intermittent versus continuous), should be correlated with in vivo data from animal models. The current evidence suggests that downstream from the initial mechanotransduction event at focal adhesions which link the extracellular matrix to the cytoskeleton, mechanically induced remodelling is mediated by a complex feedback mechanism involving the synthesis of cytokines such as interleukin-1 (IL-1), IL-6, and receptor activator of nuclear factor k B ligand by cells of the osteoblast and/or fibroblast lineages. These in turn act in an autocrine/paracrine fashion to regulate the expression of transcription factors, cytokines, growth factors, enzymes, and structural molecules involved in the differentiation, proliferation, and function of mesenchymal and other cell types. Contrary to the impression gained from the literature, tooth movement is not confined to events within the periodontal ligament. Orthodontic tooth movement involves two interrelated processes: (1) deflection or bending of the alveolar bone and (2) remodelling of the periodontal tissues.

PMID: 16687469 [PubMed - indexed for MEDLINE]

Initial changes in pulpal microvasculature during orthodontic tooth movement: a stereological study.

Eur J Orthod. 2006 Jun;28(3):217-20

Authors: Santamaria M, Milagres D, Stuani AS, Stuani MB, Ruellas AC

Any alteration in blood flow or vascular pressure caused by a trauma may damage the pulp tissue. The aim of this study was to evaluate the vascular changes during the initial period of tooth movement. These alterations were assessed in coronal molar pulp tissue of 20 male Wistar rats, 90 days of age, submitted to mesial inclination movement by a closed coil spring, placed from the right maxillary first molar to the maxillary incisors. The animals were divided into three experimental groups of 6, 24, and 72 hours of 0.4 N force application, with five animals in each group, and a control group of five animals without tooth movement. The volume density of blood vessels (V(v)) of the coronal pulp tissue in the experimental groups was calculated by stereology and compared with the control group. The results demonstrated a significant increase in V(v) at 6 hours of 10.2 per cent compared with 7.2 per cent for the control group (P <or= 0.05). At 24 and 72 hours, V(v) was reduced, with values close to those observed for the control group (P > 0.05). These results demonstrate the high capacity of adaptation of the pulp tissue to an aggression, provided the biological limits of tolerance of the pulp are respected.

PMID: 16675546 [PubMed - indexed for MEDLINE]

Unilateral molar distalization with a modified slider.

Eur J Orthod. 2006 Aug;28(4):361-5

Authors: Sayinsu K, Isik F, Allaf F, Arun T

Although there are numerous publications on bilateral non-compliance molar distalization appliances, there is limited information on problems such as asymmetrical unilateral Class II malocclusions. The aim of the present investigation was to examine the distalization of molars unilaterally in patients with a unilateral Class II molar relationship utilizing a Keles Slider, designed without a bite plane. Ten girls (mean age 13.94 +/- 2.13 years) and seven boys (mean age 13.12 +/- 1.51 years) comprised the study material. Following insertion of the appliance, the patients were seen monthly and the screw was reactivated every 2 months. After a super-Class I molar relationship was achieved, the appliance was removed and the molars were stabilized with a Nance appliance for 2 months before the second-phase of orthodontic treatment. The Nance appliance was maintained in the palate until the end of canine distalization. Lateral cephalometric radiographs were obtained before and immediately after insertion of the molar distalizer. The results showed that the maxillary first molars were distalized bodily on average by 2.85 mm. The maxillary first premolars moved forward bodily 2 mm and were extruded 2.03 mm. In all, 1.32 mm of protrusion, 1.12 mm of extrusion, and 1.79 degrees of proclination of the upper incisors were observed. The mandibular incisors and mandibular molars erupted 0.83 and 0.95 mm, respectively. The unilateral Keles Slider distalized molars successfully to a Class I molar relationship.

PMID: 16648210 [PubMed - indexed for MEDLINE]

Mechanical loading stimulates expression of connexin 43 in alveolar bone cells in the tooth movement model.

Cell Commun Adhes. 2006 Jan-Apr;13(1-2):115-25

Authors: Gluhak-Heinrich J, Gu S, Pavlin D, Jiang JX

Bone osteoblasts and osteocytes express large amounts of connexin (Cx) 43, the component of gap junctions and hemichannels. Previous studies have shown that these channels play important roles in regulating biological functions in response to mechanical loading. Here, we characterized the distribution of mRNA and protein of Cx43 in mechanical loading model of tooth movement. The locations of bone formation and resorption have been well defined in this model, which provides unique experimental systems for better understanding of potential roles of Cx43 in bone formation and remodeling under mechanical stimulation. We found that mechanical loading increased Cx43 mRNA expression in osteoblasts and bone lining cells, but not in osteocytes, at both formation and resorption sites. Cx43 protein, however, increased in both osteoblasts and osteocytes in response to loading. Interestingly, the upregulation of Cx43 protein by loading was even more pronounced in osteocytes compared to other bone cells, with an appearance of punctate staining on the cell body and dendritic process. Cx45 was reported to be expressed in several bone cell lines, but here we did not detect the Cx45 protein in the alveolar bone cells. These results further suggest the potential involvement of Cx43-forming gap junctions and hemichannels in the process of mechanically induced bone formation and resorption.

PMID: 16613785 [PubMed - indexed for MEDLINE]

[Effects of He-Ne laser irradiation on the expression of transforming growth factor beta1 during experimental tooth movement in rabbits]

Shanghai Kou Qiang Yi Xue. 2006 Feb;15(1):52-7

Authors: Sun XH, Wang R, Zhang XY

PURPOSE: The purpose of this study is to investigate the effect of He-Ne laser irradiation on the expression of transforming growth factor beta1 (TGF-beta1) during experimental tooth movement in rabbits. METHODS: Thirty-five rabbits were used in this study. The animals were randomly divided into 7 groups equally: normal group and experimental (1, 3, 5, 7, 14, 21 days) groups, 5 rabbits in each group. An orthodontic appliance, consisting of a coil spring was ligated to the bilateral first maxillary molar and connected to an orthodontic wire ligated onto the incisors, and exerting a force of approximately 80 g. The left side was used as control, and the right side was designed as irradiated side. The animals from each group were sacrificed at the time discontinued. The histological sections were proceeded with immunohistochemical staining of TGF-beta1. Then it was analyzed by Computer Image Analyzing System and statistically processed with SPSS10.0 software package for the paired Student's t test. RESULTS: The expression of TGF-beta1 was demonstrated in the area of tension and pressure of periodontium tissue in both of the irradiated and control sides. The TGF-beta1 staining in the pressure area of the irradiated side decreased significantly at 1 day (P<0.05) compared with the control side. TGF-beta1 staining increased significantly at 3 to 5 days in the pressure area (P<0.05). But in the tension area of the irradiated side, TGF-beta1 staining were significantly increased at 3 to 7 days (P<0.05). The peak value of the area of tension and pressure both appeared at the same time of the 5th day. CONCLUSION: It is concluded that He-Ne laser irradiation can effectively accelerate the expression of TGF-beta1 in periodontal tissue of rabbits during experimental tooth movement.

PMID: 16525610 [PubMed - in process]

Compressive force induces osteoblast apoptosis via caspase-8.

J Dent Res. 2006 Mar;85(3):240-4

Authors: Goga Y, Chiba M, Shimizu Y, Mitani H

Periodontal remodeling during orthodontic tooth movement is a result of mechanical stresses. The application of excessive orthodontic force induces cell death. However, the nature of compressive force-induced cell death is unclear. We examined whether the in vitro application of continuous compressive force would induce apoptosis in human osteoblast-like cells (MG-63 cells), and investigated the mechanism by which apoptosis was initiated. The cells became aligned irregularly, and cell viability decreased, indicating that the compressive force caused cell death. According to the TUNEL analysis, the number of apoptotic cells increased significantly in a time-and force-dependent manner. Caspase-3 activity increased with the magnitude of the compressive force, and this effect was reduced significantly by a caspase-8 inhibitor, whereas a caspase-9 inhibitor had no such effect. We conclude that the in vitro application of compressive force can induce apoptosis in MG-63 cells through the activation of caspase-3 via the caspase-8 signaling cascade.

PMID: 16498071 [PubMed - indexed for MEDLINE]

Effects of a segmented removable appliance in molar distalization.

Eur J Orthod. 2006 Feb;28(1):65-73

Authors: Akin E, Gurton AU, Sagdic D

The aim of the present investigation was to evaluate the skeletal and dentoalveolar treatment effects of a segmented removable appliance [removable molar distalizer (RMD)] for molar distalization. The study was conducted on 28 patients (12 females and 16 males), with a mean age of 11.8 years. All presented with a skeletal Class I malocclusion and a bilateral dental Class II molar relationship. The pre- and post-distalization records included lateral head films, study models and standard photographs. The findings were evaluated with a paired samples t-test. The average maxillary first molar distalization with the RMD was 3.98 mm, with 4.61 degrees of distal tipping. The maxillary second premolars drifted distally 2.13 mm on average with 1.54 degrees of distal tipping, while the maxillary first premolars showed 1.23 mm of mesial movement and 1.98 degrees of mesial tipping. The incisors protruded 1.09 mm with 1.27 degrees of labial tipping. The RMD was effective in distal molar movement and all patients attained a bilateral Class I molar relationship in an average period of 4.5 months. Hygiene problems and mucosal irritations, frequently found with fixed intraoral distalization techniques, were not observed during the distalization period.

PMID: 16436365 [PubMed - indexed for MEDLINE]

The treatment effects of Invisalign orthodontic aligners: a systematic review.

J Am Dent Assoc. 2005 Dec;136(12):1724-9

Authors: Lagrav&#xE8;re MO, Flores-Mir C

BACKGROUND: The authors conducted a systematic review of the literature to determine the treatment effects of the Invisalign orthodontic system (Align Technology), Santa Clara, Calif.). TYPES OF STUDIES REVIEWED: The authors reviewed clinical trials that assessed Invisalign's treatment effects in nongrowing patients. They did not consider trials involving surgical or other simultaneous fixed or removable orthodontic treatment interventions. RESULTS: The authors searched electronic databases (PubMed, MEDLINE, MEDLINE In-Process & Other Non-Indexed Citations, Evidence Based Medicine Reviews, EMBASE Excerpta Medica, Thomsen's ISI Web of Science and LILACS) with the help of a senior health sciences librarian. They used "Invisalign" as the sole search term, and 22 documents appeared in the combined search. Thereafter, they used "clinical trials," "humans" and "Invisalign treatment effects" as abstract selection criteria. Only two published articles met these inclusion criteria, though after reading the actual articles, the authors determined that they did not adequately evaluate Invisalign treatment effects. Both articles identified methodological issues. CLINICAL IMPLICATIONS: The inadequately designed studies the authors found represented only a lower level of evidence (level II). Therefore, the authors found that no strong conclusions could be made regarding the treatment effects of Invisalign appliances. Future prospective randomized clinical trials are required to support, with sound scientific evidence, the claims about Invisalign's treatment effects. Clinicians will have to rely on their Invisalign clinical experience, the opinions of experts and the limited published evidence when using Invisalign appliances.

PMID: 16383056 [PubMed - indexed for MEDLINE]

Root resorption associated with orthodontic force in inbred mice: genetic contributions.

Eur J Orthod. 2006 Feb;28(1):13-9

Authors: Al-Qawasmi RA, Hartsfield JK, Everett ET, Weaver MR, Foroud TM, Faust DM, Roberts WE

Root resorption (RR) is an unwanted sequela of orthodontic treatment. Despite rigorous investigation, no single factor or group of factors that directly causes RR has been identified. The purpose of this study was to examine the effect of the genotype on susceptibility or resistance to develop RR secondary to orthodontic force. Nine-week-old male mice from eight inbred strains were used and randomly distributed into control (C) or treatment (T) groups as follows: A/J (C = 9,T = 9), C57BL/6J (C = 7,T = 8), C3H/HeJ (C = 8,T = 6), BALB/cJ (C = 8,T = 6), 129P3/J (C = 6,T = 8), DBA/2J (C = 8,T = 9), SJL/J (C = 8,T = 10), and AKR/J (C = 9,T = 8). Each of the treated mice received an orthodontic appliance to tip the maxillary left first molar mesially for 9 days. Histological sections of the tooth were used to determine RR and tartrate resistant acid phosphatase (TRAP) activity. The Wilcoxon ranked-sum non-parametric test was used to evaluate differences between the groups. The results showed that the DBA/2J, BALB/cJ, and 129P3/J inbred mouse strains are highly susceptible to RR, whereas A/J, C57BL/6J and SJL/J mice are much more resistant. The variation in the severity of RR associated with orthodontic force among different inbred strains of mice when age, gender, food, housing, and orthodontic force magnitude/duration are controlled support the hypothesis that susceptibility or resistance to RR associated with orthodontic force is a genetically influenced trait.

PMID: 16373453 [PubMed - indexed for MEDLINE]

Relationship between substance P and interleukin-1beta in gingival crevicular fluid during orthodontic tooth movement in adults.

Eur J Orthod. 2006 Jun;28(3):241-6

Authors: Yamaguchi M, Yoshii M, Kasai K

Metabolism by peptidases plays an important role in modulating the levels of biologically-active neuropeptides, while that of substance P (SP), a component of gingival crevicular fluid (GCF), may potentiate the inflammatory process in orthodontic tooth movement. The aim of this study was two-fold: (1) to investigate GCF levels of SP and interleukin-1beta (IL-1beta) during human orthodontic tooth movement, and (2) to determine the correlation coefficients between SP and IL-1beta levels in the GCF. The subjects were 3 males, with a mean age of 21.3 +/- 2.8 years old, and 6 females, with a mean age of 23.1 +/- 2.4 years, undergoing orthodontic movement of a single tooth, with the contralateral tooth used as the control. GCF was sampled at the control and treatment (compression) sites before and 1, 4, 8, 24, 72, 120, and 168 hours after initiation of orthodontic treatment. Prevention of plaque-induced inflammation allowed assessment of the dynamics of mechanically stimulated SP and IL-1beta levels in the GCF, which were determined using enzyme-linked immunosorbent assay (ELISA) kits. GCF levels of SP and IL-1beta for the treated teeth were significantly higher (P < 0.001) than for the corresponding control teeth from 8 to 72 hours, and peaked at 24 hours. These results show that the amounts of SP and IL-1beta in GCF increase with orthodontic tooth movement, and indicate that such increases may be involved in inflammation in response to mechanical stress.

PMID: 16373450 [PubMed - indexed for MEDLINE]

Observations on the use and clinical effectiveness of lacebacks.

J Orthod. 2005 Dec;32(4):294-5; author relpy 295-6

Authors: Bennett J

PMID: 16333051 [PubMed - indexed for MEDLINE]

Clinical pearl: clinical tips with System-R.

J Orthod. 2005 Dec;32(4):244-6

Authors: Parkin N

The article describes the versatility and ease of use of a relatively new bracket system manufactured by GAC called System-R. This system consists of two bracket types; standard width and reduced width, both of which have an active self-ligating clip. The reduced friction offered by this system allows different mechanics to be employed. Security of ligation and absence of decaying force values allows longer treatment intervals. Fast and reliable opening and closing of the clips means reduced chairside time. Difficulties experienced personally by these brackets are highlighted and some troubleshooting tips are included.

PMID: 16333045 [PubMed - indexed for MEDLINE]

Localized sequential use of resilient lining to generate orthodontic force in thermoformed active removable appliances.

J Orthod. 2005 Dec;32(4):235-40

Authors: Ng EW

A new modality of orthodontic treatment based on the thermoformed appliance was developed and trialled clinically. A light-cured resilient lining material commonly used for denture relining was placed locally and sequentially in thermoformed appliances to generate orthodontic forces. The new method appeared to be effective. All the presented cases showed substantial improvement in dental alignment. A number of orthodontic movements were demonstrated. Localized use of resilient lining in thermoformed orthodontic appliances appeared to be a promising alternative to other thermoformed active removable appliance (TARA) treatments. Further studies are required to optimize the procedures and explore its full potential.

PMID: 16333043 [PubMed - indexed for MEDLINE]

Essix-based molar distalization appliance.

J Orthod. 2005 Dec;32(4):229-34

Authors: Babacan H, Doruk C

A new design of molar distalization appliance and its fabrication are described in this article. This case report illustrates distal movement of mandibular molars with negligible loss of anterior anchorage. This new vacuum-formed Essix appliance can be a reasonable alternative to conventional appliances.

PMID: 16333042 [PubMed - indexed for MEDLINE]

Rescue surgery (surgical repositioning) of impacted lower second molars.

Med Oral Patol Oral Cir Bucal. 2005 Nov-Dec;10(5):448-53

Authors: Garc&#xED;a-Calderón M, Torres-Lagares D, González-Martín M, Gutiérrez-Pérez JL

The impaction of lower second molars, given that its incidence is 0.03 to 0.21%, is a rare complication in tooth eruption. It has been detected more often in unilateral form than bilateral and is more common in the mandible than in the maxillary. It has a slight predilection for males, and mesial inclination is more usual. A wide variety of therapeutic approaches have been published, basically referring to surgical techniques, independent or complemented by means of orthodontic technical aids, with the aim of placing the tooth in the correct position, and which are encompassed under the concept of surgical rescue. In cases resolved with repositioning of an impacted tooth, prophylactic root extraction has been proposed as obligatory. We present a case of a 12 and a half year old patient referred to the University of Seville due to non-eruption of the left lower second molar. The patient was referred by her orthodontist, who detected the impaction before starting orthodontic treatment. The orthodontist requested that, if it was possible, we did not extract the root of the third molar, because its eruption would be feasible in the future (there would be sufficient space in the arch). The spaces available were measured and we decided to attempt the repositioning of the impacted tooth without extracting the root of the wisdom tooth, which was carried out successfully.

PMID: 16264380 [PubMed - indexed for MEDLINE]

A comparative study of dental arch widths: extraction and non-extraction treatment.

Eur J Orthod. 2005 Dec;27(6):585-9

Authors: Işik F, Sayinsu K, Nalbantgil D, Arun T

The aim of this study was to determine the pre- and post-treatment width changes in the canine, premolar and molar regions in subjects treated with extraction of four first premolars, non-extraction, and non-extraction with rapid maxillary expansion (RME). Pre- and post-treatment orthodontic study models of 60 females (13.83 +/- 2.77 years) and 24 males (14.33 +/- 2.67 years) who underwent comprehensive orthodontic therapy were evaluated. Forty-two were treated non-extraction with fixed appliance therapy, 15 non-extraction with RME, and 27 with extraction of the first premolars. In addition to standard descriptive statistical calculations, one way ANOVA was used for comparison of the groups, and the post hoc Tukey multiple comparison test for comparison of the subgroups. The results revealed that the distance between the upper canines was not affected by the treatment modality. Upper premolar and molar arch widths increased more in the non-extraction subjects when compared with those with extractions, with the greatest increase in patients with RME. In the lower canine area the extraction group showed the widest arch width at the end of treatment. There was also a 0.60 mm decrease in the lower canine width in the non-extraction group. A decrease was found in lower inter-premolar and molar distances due to consolidation of the extraction spaces. When making a decision between non-extraction with maxillary expansion and extraction treatment modalities in borderline cases where there is constriction in the upper inter-premolar distance, apart from taking profile values into consideration, it should be borne in mind that expansion treatment can be helpful in achieving a wider arch form.

PMID: 16257988 [PubMed - indexed for MEDLINE]

Cell transplantation in wounded mixed connective tissues.

Anat Rec A Discov Mol Cell Evol Biol. 2005 Dec;287(2):1256-63

Authors: Lekic PC, Nayak BN, Al-Sanea R, Tenenbaum H, Ganss B, McCulloch C

Direct transplantation of multipotent precursor cells into the periodontium could provide a therapeutic approach for restoring periodontal tissues destroyed by periodontitis or trauma. To improve the understanding of cell migration, proliferation, and differentiation, we used a rodent model combining orthodontic tooth movement and transplantation of Lac-Z-positive murine-cultured periodontal ligament (PL) or femur-derived bone marrow precursor cells into a defined mandibular wound site, thus promoting tissue regeneration in wounded periodontium. Our results show that in orthodontically traumatized tissues, transplanted PL and bone marrow cells migrated systemically, contributing to the repopulation of sites with reduced cell/matrix density. The transplanted PL cells proliferated in adjacent alveolar bone marrow spaces, thus migrating to vascular tissues in the PL. The capillary walls in the PL serve as delivery sites for these cells and other marrow-derived hematopoietic cells, including monocytes. The transplanted marrow cells, extracted from femur of transgenic (TgR) mice exhibited similar behavior to those of transplanted PL cells, showing high proliferative activity in alveolar marrow as well as intensive repopulating capacity in wounded periodontium. On the other hand, the buccal skin fibroblasts failed to migrate and home effectively and thus the transplantation of these cells had no effect on periodontium regeneration. Based on these results, we conclude that the transplanted PL and bone marrow cells migrate systemically and following a cyclical process of growth and development and differentiate into PL fibroblasts, osteoblasts, and cementoblasts, thereby contributing to periodontal regeneration.

PMID: 16247794 [PubMed - indexed for MEDLINE]

Osteoclastogenic activity during mandibular distraction osteogenesis.

J Dent Res. 2005 Nov;84(11):1010-5

Authors: Wang LC, Takahashi I, Sasano Y, Sugawara J, Mitani H

Mandibular distraction osteogenesis is a well-developed clinical modality for the treatment of craniofacial deformities and dental arch discrepancies, in combination with orthodontic treatment. However, in our previous study, orthodontic tooth movement into the distraction gap caused severe root resorption. The present study aimed to clarify the osteoclastogenic activity of cells in the distraction gap. We hypothesized that the gene expression of osteoclastogenic- and osteoclast-supporting molecules in osteoblasts and stromal cells would increase at distraction sites during the consolidation period. An animal model experiment involving rabbits was designed for mandibular distraction osteogenesis and subjected to in situ hybridization analysis. The number of osteoclasts was larger in the distraction gap during the early consolidation period than in normal controls, due to an increase of gene expression for osteoclastogenic cytokines in osteoblasts. It was concluded that osteoclastogenic and osteoclastic activities are stimulated at distraction sites during the early consolidation period.

PMID: 16246932 [PubMed - indexed for MEDLINE]

Early responses of periodontal ligament cells to mechanical stimulus in vivo.

J Dent Res. 2005 Oct;84(10):902-6

Authors: Kawarizadeh A, Bourauel C, G&#xF6;tz W, Jäger A

Previous studies have indicated that human periodontal ligament cells undergo osteoblastic differentiation via the ERK pathway under mechanical stress in vitro. This study aimed to verify this principle in vivo. The right upper first molars of 25 anesthetized rats were loaded with constant forces of 0.1 N for up to 8 hrs. The untreated contralateral side served as a control. Paraffin-embedded sections were analyzed by immunohistochemistry for proliferating cell nuclear antigen (PCNA), runt-related transcription factor 2 (Runx2/Cbfa1), and phosphorylated extracellular signal-regulated kinases 1/2 (pERK1/2). In selected areas under tension, the proportions of Runx2-positive and pERK1/2-positive cells increased within 8 hrs of loading, whereas these proportions in selected areas under pressure were significantly lower than those in control teeth. Moreover, there were no significant changes in the number of PCNA-positive cells. Thus, mechanical stimulus up-regulates Runx2, and this regulation may be achieved via the ERK pathway.

PMID: 16183788 [PubMed - indexed for MEDLINE]

A 2-year outcome audit of a versatile orthodontic bone anchor.

J Orthod. 2005 Sep;32(3):175-81

Authors: Mommaerts MY, Michiels ML, De Pauw GA

This study examined complications leading to, or possibly leading to, treatment failure, related to the use of the orthodontic bone anchor (OBA). The OBA is a potential means of providing absolute anchorage and consists of a base-plate fixed with mono-cortical screws, a neck piercing the soft tissues, and a coronal part with conventional orthodontic hooks, tubes or slots. The investigation took the form of a single centre prospective registry at a supra-regional teaching hospital. Eighteen patients (average age 21 years) had one to four OBAs placed between January 2000 and February 2002. Altogether 35 OBAs were placed. Follow-up took place until April 2004. Reasons for placing the OBAs were noted together with any associated complications during the follow-up period. Twenty-three OBAs have been removed so far, four prematurely (one of them before it was taken into use, due to a change of treatment plan enforced by loss of the contralateral OBA). Nineteen were removed as planned after completion of the intended tooth movements. Common (but minor) complications included granulations, acute gingivitis and gingival recession. Light mobility of the OBA was also noted in some cases, but without clinical repercussions. The OBA can be loaded directly, at the level of the orthodontic archwire or more occlusally. It can be placed at any site at the circumference of the jaws, given good quality and thickness of the bony wall. Conventional biomechanical techniques can be applied. However, the failure rate (premature loss of OBA) of 8.6% is considered high, and has necessitated changes in the hardware and protocol.

PMID: 16170058 [PubMed - indexed for MEDLINE]

The diary of an orthognathic patient aged 30 3/4.

J Orthod. 2005 Sep;32(3):169-74

Authors: Murphy TC

This article reports on the experiences of an orthodontist who has actually undergone combined orthodontic and orthognathic treatment. The aim is to give the reader an insight into not only what we, the orthodontists, fail to tell our orthognathic patients, but also what they fail to tell us.

PMID: 16170057 [PubMed - indexed for MEDLINE]

Evolution of flexural rigidity according to the cross-sectional dimension of a superelastic nickel titanium orthodontic wire.

Eur J Orthod. 2005 Aug;27(4):402-7

Authors: Garrec P, Tavernier B, Jordan L

The choice of the most suitable orthodontic wire for each stage of treatment requires estimation of the forces generated. In theory, the selection of wire sequences should initially utilize a lower flexural rigidity; thus clinicians use smaller round cross-sectional dimension wires to generate lighter forces during the preliminary alignment stage. This assessment is true for conventional alloys, but not necessarily for superelastic nickel titanium (NiTi). In this case, the flexural rigidity dependence on cross-sectional dimension differs from the linear elasticity prediction because of the martensitic transformation process. It decreases with increasing deflection and this phenomenon is accentuated in the unloading process. This behaviour should lead us to consider differently the biomechanical approach to orthodontic treatment.The present study compared bending in 10 archwires made from NiTi orthodontics alloy of two cross-sectional dimensions. The results were based on microstructural and mechanical investigations. With conventional alloys, the flexural rigidity was constant for each wire and increased largely with the cross-sectional dimension for the same strain. With NiTi alloys, the flexural rigidity is not constant and the influence of size was not as important as it should be. This result can be explained by the non-constant elastic modulus during the martensite transformation process. Thus, in some cases, treatment can begin with full-size (rectangular) wires that nearly fill the bracket slot with a force application deemed to be physiologically desirable for tooth movement and compatible with patient comfort.

PMID: 16043477 [PubMed - indexed for MEDLINE]

Validation of two-dimensional measurements of root resorption craters on human premolars after 28 days of force application.

Eur J Orthod. 2005 Aug;27(4):390-5

Authors: Chan EK, Petocz P, Darendeliler MA

The aims of this study were to develop a three-dimensional (3D) mathematical model of a typical root resorption crater and to correlate two-dimensional (2D) surface area measurements to 3D volumetric measurements of root resorption craters created under light and heavy orthodontic forces. Data were obtained from a previous study of 36 first premolars from 16 subjects requiring extraction of these teeth as part of their orthodontic treatment. Buccal tipping forces of 25 or 225 g were applied for an experimental period of 28 days. After extraction, the samples were prepared for scanning electron microscopy (SEM) imaging, image processing and analysis. Surface area (2D) and volumetric (3D) measurements of all craters were obtained. A mathematical analysis of the 2D/3D relationship enabled the determination of an appropriate digital model for the shape, type and dimensions of resorption craters, which was also able to distinguish between a 'hemispheric' model versus a 'layered' model of craters.The results demonstrated that 2D and 3D measurements were strongly correlated (r = 0.991**). Within the light and heavy force groups, the measurements were also strongly correlated (r = 0.978** and r = 0.994**, respectively). For a 28 day experimental period, 2D measurements of root resorption craters were found to be as reliable as 3D measurements.

PMID: 16043475 [PubMed - indexed for MEDLINE]

Alterations in gingival dimensions following rapid canine retraction using dentoalveolar distraction osteogenesis.

Eur J Orthod. 2005 Aug;27(4):324-32

Authors: G&#xFC;rgan CA, Işeri H, Kişnişci R

The aim of this clinical prospective study was to evaluate the alterations that occurred in the gingival dimensions of canine teeth following dentoalveolar distraction (DAD) during a 12 month follow-up period.The study sample comprised 36 maxillary canines of 18 growing or adult subjects with a mean age of 16.94 years (13.08-25.58 years) at the start of treatment. Full retraction of the canines was achieved in 10.36 +/- 1.93 days (range 8-14 days) at a rate of 0.8 mm/day using a custom-made intraoral rigid tooth-borne distraction device. Before surgery (pre-DAD), immediately after removal of the device (post-DAD), and at 1, 6, and 12 months post-DAD, the plaque index (PI), gingival index (GI), pocket depth (PD) and width of keratinized gingiva were recorded and the width of attached gingiva was calculated. The alterations in clinical measurements among different evaluation periods were analysed by Friedman and repeated measure ANOVA tests.There were significant differences between pre- and post-DAD for PD measurements for all sites, with the highest at the distal site. The palatal sites likewise showed significant differences at the 1, 6, and 12 month follow-up periods compared with the post-DAD period. The buccal sites showed no significant changes at any time point. The width of keratinized gingiva also showed no significant change during the follow-up period, while the width of attached gingiva was significant only between the pre- and post-DAD periods (P < 0.01). On the basis of the above findings, it could be concluded that DAD is an innovative technique with no unfavourable long-term effects on the gingival tissues of rapidly retracted canine teeth.

PMID: 16043471 [PubMed - indexed for MEDLINE]

Distraction osteogenesis may promote periodontal bone regeneration.

J Dent Res. 2005 Aug;84(8):757-61

Authors: Faber J, Azevedo RB, B&#xE1;o SN

Distraction osteogenesis has numerous applications in the treatment of conditions affecting the dentofacial complex, from midface advancement to orthodontic tooth movement produced by transversal distraction of the periodontal ligament. The purpose of this study was to test the hypothesis that periodontium can be consistently distracted toward the tooth crown to promote periodontal bone regeneration. After the surgical production of periodontal defects in maxillary canines of 5 mongrel dogs, periodontal bone distraction was performed. Light microscopy was used for histopathological and morphometric analysis. Periodontal bone regeneration occurred in all animals. Periodontal bone regeneration in the distraction sites (Mean +/- SD: 5.45 +/- 2.01 mm) differed from that in control sites (0.008 +/- 0.67 mm; p < 0.0001). Periodontal bone distraction resulted in periodontal bone regeneration. This finding may establish periodontal bone distraction as a new treatment alternative for periodontal defects.

PMID: 16040736 [PubMed - indexed for MEDLINE]