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PubMed1980

Surgical-orthodontic correction of maxillary retrusion by Le Fort I osteotomy and proplast.

The combined efforts of the orthodontist and surgeon are necessary for successful treatment of most patients with maxillary retrusion. Both the aesthetic and functional manifestations of this dento-facial deformity can usually be effectively treated by maxillary advancement, augmentation of the midfacial region and orthodontics. Treatment planning, pre- and post-surgical orthodontic treatment principles, and surgical considerations in treating 25 adults with maxillary retrusion are described and illustrated. Surgical advancement of the maxilla by Le Fort I osteotomy, proper alignment of the teeth by orthodontics, and augmentation of the paranasal, canine fossae and malar regions with Proplast, were the common denominators of successful treatment.

Adolescent↗

PubMed1996

The measurement of acid and alkaline phosphatase in gingival crevicular fluid during orthodontic tooth movement.

This study examines acid and alkaline phosphatase activities in gingival crevicular fluid (GCF) to learn whether bone turnover dynamics can be monitored in human subjects during orthodontic tooth movement. Three female subjects were observed longitudinally to assess tooth movement, plaque, and inflammation. For each subject, one randomly selected premolar served as the control and was not treated, and another was moved buccally with 100 gm of force. The GCF was collected weekly and assayed for phosphatases. Alkaline phosphatase peaked between the first and third weeks, followed by an increase in acid phosphatase between the third and sixth weeks. After the first week, tooth movement averaged 0.9 mm. Additional 0.9 mm of movement occurred during the next 3 weeks, followed by 1.4 mm during weeks 4 to 6. Thirty additional patients, randomly divided into headgear/biteplate, bionator, and control groups, were also sampled cross-sectionally at the maxillary first molars. The GCF phosphatase activities were assessed as functions of location on the tooth, treatment modality, duration of treatment, gingival inflammation, and plaque accumulation. The plaque index did not show a relationship to either acid or alkaline phosphatase activity on the mesial or distal in the treated groups. However, alkaline phosphatase increased with inflammation on the distal in treated groups and acid phosphatase was consistently higher on the mesial than on the distal in the treatment groups. Alternating peaks of acid and alkaline phosphatase were found in the GCF of treated teeth as functions of treatment duration. The sequence of these changes is similar to that reported for alveolar bone turnover in a rodent orthodontic tooth movement model. We conclude that phosphatase activities in GCF may be a useful means for monitoring tissue responses to orthodontic treatment.

Acid Phosphatase↗

PubMed1996

Early tooth movement pattern after application of a controlled continuous orthodontic force. A human experimental model.

This clinical study was designed to investigate early orthodontic movement of human premolars subjected to a controlled, continuous, horizontally directed force. The maxillary right, first or second premolar in 56 children, 18 boys and 38 girls (mean age 13.8 years), was moved buccally with a fixed orthodontic appliance with a frontal bite-block disengaging the occlusion. The contralateral premolar served as control. A weekly controlled and reactivated force of 50 cN (approximately 50 gm) was applied. The force declined on average about 24% per week. The patient material was subgrouped to comprise eight patients in each of seven groups, for which the experimental periods varied from 1 to 7 weeks. Tooth displacement was studied on dental casts, with a coordinate measuring machine (Validator 100, TESA SA, Renens, Switzerland), which made it possible to measure the displacement in three dimensions. The movement pattern of the test teeth was found to be a combination of horizontal and vertical displacements, including tipping. The horizontal movement of the tooth crown was on average 0.8 mm during the first week and 3.7 mm after 7 weeks. The vertical movements were intrusive in 45% and extrusive in 55% of the teeth. In some tipping movements, the crown was "intruded" at the same time as the apex was "extruded." The individual variations in tooth displacements were considerable. The clinical experimental model used permits detailed study of orthodontic tooth movement under controlled force conditions, as well as detailed histologic analysis of related root resorption.

Adolescent↗

PubMed1997

Heritability of 39 orthodontic cephalometric parameters on MZ, DZ twins and MN-paired singletons.

The twin method is one of the most effective methods available for investigating genetically determined variables in orthodontics, as well as in other medical fields, depending on the variance in the shape and the size of skull and teeth, both on genetic and environmental influences. The former have been extensively evaluated and, in particular, most of the facial and dental cephalometric parameters have shown high heritability, the vertical parameters have a higher genetic control compared with the horizontal ones. Nevertheless, most of the results provided by twin research have been considered arbitrary if directly transferred to a singleton population and in further studies, including extensive analysis of the parents, familial and nutritional habits have been recommended. In this study, heritability of 39 lateral orthodontic cephalometric parameters has been estimated by both statistical method of path analysis and Dahlberg' quotient in three orthodontic samples of young monozygotic and dizygotic twins and same-sex pairs of singletons living together, matched for sex and age, to evaluate genetic versus environmental factors affecting heritability of craniofacial features in the aim to obtain results not only statistically significant but also transferrable to a singleton population. Different inheritance trends, showing the highest concordance of values between monozygotic twin pairs when compared with dizygotic twin pairs or the same-sex singletons paired group, come from the 39 selected lateral cephalometric parameters, confirming the hypothesis that strong genetic control is exerted especially on the vertical ones. Heritability seems to have more influence on anterior vertical parameters than posterior. Mandibular structure seems to be more genetically determined than mandibular size. All five Ricketts' cephalometric typological parameters confirm high heritability coefficients, the same applies to the linear horizontal McNamara's measurement and lower incisor to A-Pg line. The two tested statistical methods showed relevant concordance of results.

Adolescent↗

PubMed1998

Later orthodontic appliance reactivation stimulates immediate appearance of osteoclasts and linear tooth movement.

BACKGROUND: Delays in the appearance of osteoclasts at compression sites occur after orthodontic appliance reactivation, when this is done during both the period of osteoclast recruitment and the peak expansion in the osteoclast population. This experiment examines osteoclasts and tooth movement in alveolar bone after appliance reactivation coinciding with alveolar bone formation and the time when reactivation osteoclasts first appear (ie, 10 days after initial appliance activation). METHODS: Bilateral orthodontic appliances were activated to mesially tip maxillary molars with 40 cN in 144 rats. After 10 days, all rats were randomized into two groups of 72. Group I had appliances reactivated in precisely the same manner as the first activation. Group II had appliances sham-reactivated. Nine to 12 rats were then sacrificed at 1, 3, 5, 7, 10, and 14 days in both groups (eg, day 1 represents an interval of 11 days after the first appliance activation and 1 day after either sham or real reactivation). Orthodontic movement was measured cephalometrically; changes in osteoclasts and root resorption were assessed at both compression and tension sites histomorphometrically. RESULTS: Teeth in the reactivated group (Group I) displayed linear tooth movement (62.6 micrometers/day), and 0.9 mm tooth movement by day 10. Significant increases in osteoclast numbers, osteoclast surface percentage, and surface per individual osteoclast were evident in these animals by 1 day postreactivation (P <.01). Significant treatment-related increases in root resorption were not evident at compression sites at any time. CONCLUSIONS: These findings indicate that, after appliance reactivation during the time when reactivation osteoclasts appear, a second cohort of osteoclasts can be recruited immediately, along with immediate and substantial tooth movement and no greater risk of root resorption.

Alveolar Process↗

PubMed1998

Diurnal variation in tooth movement in response to orthodontic force in rats.

The purpose of this study was to determine whether there is any difference in orthodontic tooth movement when the orthodontic force is applied at different times of the day. Twenty-four rats were divided into three experimental groups based on the time of day that maxillary expansive force was applied; i.e., the force was applied continuously throughout the entire experimental period of 21 days in animals in the whole-day group; animals in the dark-period group and the light-period group received force only during the dark period (19:00-07:00) or the light period (07:00-19:00), respectively. Maxillary expansion in the light-period group was about 2 times greater than that in the dark-period group on day 21. There was no significant difference in expansion between the light-period group and the whole-day group. An experiment that used chronologic labeling with NTA-Pb revealed that there was greater formation of new bone on the tension side in the light-period group than in the dark-period group. There was no significant difference in the width of the palate among the three groups. These results indicate that there is a diurnal variation in tooth movement in response to orthodontic external force and that the application of force during the animal's rest period may be more effective than that while it is active.

Analysis of Variance↗

PubMed1999

Gingival response to orthodontic force.

Orthodontic tooth movement is brought about by prolonged application of force on the attachment apparatus. This results in cellular and extracellular changes within the periodontium. As shown in numerous studies, tooth movement is achieved after the remodeling of alveolar bone and the response of the periodontal ligament to the mechanical force. Although gingival changes have also been found to be an important factor in the overall response, the effect of orthodontic tooth movement on the gingiva has been investigated to a lesser extent. Unlike bone and periodontal ligament, which regain their original structure after removal of force, the gingival tissue does not regain its pretreatment structure, a fact on which a hypothesis has been made that tooth relapse after removal of retention may be associated with changes in the gingiva. The present review summarizes available data on the effect of orthodontic force on collagen, elastin, and collagenase in the gingiva and its relevance to understanding the mechanism of tooth relapse.

Animals↗

PubMed2004

Effects of nitric oxide in orthodontic tooth movement in rats.

The purpose of this study was to evaluate the role of nitric oxide (NO) in orthodontic tooth movement in rats. Nomega-nitro-L-arginine methyl ester (L-NAME) was used as NO synthase (NOS) inhibitor, and nitro-L-arginine (NLA) was used as NOS precursor. Fifty-four Sprague-Dawley rats were divided into 3 equal groups, and each group was divided into 3 subgroups. In the first 8 subgroups, 20 g of force was applied to the maxillary incisors with a spring. NLA was administered in the first 3 subgroups at 10(-4), 10(-5) and 10(-6) mol/L (20 microL/12 hours), respectively. L-NAME was administered in the next 3 subgroups with the same order, amount, and prescription. The last 3 subgroups were evaluated as control groups; in the seventh subgroup, 0.9% NaCl (saline solution) was injected (20 microL/12 hours). Only the force was administered in the eighth subgroup, and no chemical solution or orthodontic force was used in the last subgroup. The rats were killed on the fifth day of the experiment. Their premaxillae were dissected, and tissue sections were obtained from the coronal, middle, and apical thirds of the incisor roots. Multinuclear osteoclasts, Howship's lacunae, capillary vascularization, and orthodontic tooth movement were significantly increased in the NLA groups compared with the L-NAME and control groups.

Animals↗

PubMed1996

Mucogingival considerations in orthodontic treatment.

Alterations in the mucogingival complex will occur during orthodontic tooth movement, but these are independent of the apico-coronal width (height) of the gingiva. The integrity of the periodontium can be maintained during orthodontic therapy also in areas that have only a minimal zone of gingiva. In terms of changes in the position of the soft tissue margin and in gingival dimensions, the important factors to consider are the direction of the tooth movement and the bucco-lingual thickness of the gingiva. Lingual tooth movement will result in an increased bucco-lingual thickness of the tissue at the facial aspect of the tooth which results in coronal migration of the soft tissue margin (decreased clinical crown height). Facial tooth movement, on the other hand, will result in a reduced bucco-lingual tissue thickness and thereby a reduced height of the free gingival portion and an increased clinical crown height. The risk for development of recession type defects in conjunction with orthodontic tooth movement is present only if the tooth has been moved out of the alveolar bone housing, ie, when an alveolar bone dehiscence has been created.

Adult↗

PubMed1999

Corrosion and biocompatibility of orthodontic wires.

With the increasing number of orthodontic treatments using devices containing nickel and the growing prevalence of nickel allergy in the average population, biocompatibility studies of these devices have become a topic of major interest. The corrosion behavior of orthodontic wires is a decisive factor determining their biocompatibility. Therefore four nickel-titanium guiding arches, a titanium-molybdenum and a stainless steel wire were analyzed for corrosion behavior under realistic conditions. Pure potentiostatic, pure mechanical and combined potentiostatic and mechanical stresses were applied to the specimens. Subsequently, the surfaces of the wires were investigated employing atomic force microscopy (AFM) and nickel loss was measured with an atomic absorption spectrophotometer. The results yield information about the relative corrosion tendency of the wires under in vitro conditions. The wires examined can be classified into two groups, one with a high and a second group with a low tendency towards corrosion, that is American Orthodontics Memory wire as well as GAC Neo Sentalloy and Ormco Ni-Ti as well as Unitek Nitinol respectively. Although corrosion behavior under clinical conditions can not be directly derived from these results, analyses of wires after clinical usage indicate that changes of wire surfaces might show the same characteristics under in vitro conditions.

Journal Article↗

PubMed2002

Anisotropic orthodontic force from the hollow super-elastic Ti-Ni alloy wire by transforming the wire cross-section.

The purpose of this research was to devise a method for transforming the cross-section of the hollow super-elastic Ti-Ni alloy round wire and to examine the changes in its bending properties for clinical orthodontic application. The specimen wires were pressed with the use of heated pliers to transform the cross-sectional shape. As a result, transformation of the wire cross-section with super-elasticity was possible. As a verified by cantilever test and three-point bending test of the transformed specimens, a two-dimensional orthodontic force, which was different in each bending direction, was obtained. The hollow wire showed considerably high load level in the long axis along with markedly low load level in the short axis, which was mainly caused by the change in the moment of inertia by transforming the cross-section. It was revealed that, by transforming the wire cross-section of the hollow super-elastic Ti-Ni alloy round wires, anisotropic orthodontic force in bending properties could be obtained with super-elasticity.

Journal Article↗

PubMed2001

Orthodontic movement in bone defects augmented with Bio-Oss. An experimental study in dogs.

OBJECTIVE: To study if it was possible to move, by orthodontic means, a tooth into an area of the jaw that had been augmented with Bio-Oss. MATERIAL AND METHODS: 5 beagle dogs were used. The 1st, 2nd, and 4th mandibular premolars on each side were removed. The defect at the left 4th premolar site was filled with a biomaterial (Bio-Oss) while the corresponding defect in the right side was left for spontaneous healing. 3 months later, an orthodontic device was inserted in each side of the mandible. The device was designed to allow distal, bodily movement of the 3rd premolars. When the experimental teeth had been moved into the extraction sites of the 4th premolars, the animals were sacrificed and biopsies of the premolar-molar regions of the mandible sampled. The tissues were prepared for histological analysis using standard procedures. In the sections, 3 zones were identified: zone A=the bone tissue within the distal portion of the previous extraction site (4th premolar), zone B=the pressure side of the 3rd premolar, zone C=the tension side of the 3rd premolar. The area occupied by mineralized bone, Bio-Oss particles and bone marrow was determined by a point counting procedure. The width of the periodontal ligament as well as the percentage of the root surface (in zone B) that exhibited resorption was determined. RESULTS: The findings demonstrated that it was possible to move a tooth into an area of an alveolar ridge that 3 months previously had been augmented with a biomaterial. It was also demonstrated that 12 months after grafting, Bio-Oss particles remained as inactive filler material in the not utilized part of zone A. The biomaterial was not present in zone C but present in small amounts in zone B. CONCLUSION: During the orthodontic tooth movement the graft material (Bio-Oss) was degraded and eliminated from the part of the alveolar ridge that was utilized for the experiment. In the non-utilized part of the ridge the biomaterial, however, remained as a seemingly inactive filler material.

Alveolar Process↗

PubMed2003

Tissue reaction to orthodontic tooth movement in different bone turnover conditions.

OBJECTIVES: To study the tissue reaction to orthodontic load in normal, high, and low bone turnover states. DESIGN: 'Split mouth' design performing orthodontic tooth movement in 52, 6-month-old male rats with: normal (n = 19), high (n = 16), and low bone turnover (n = 17), the latter two being obtained by induction of hyperthyroidism and hypothyroidism, respectively. Performed at the Department of Orthodontics at Aarhus University. EXPERIMENTAL VARIABLE: The upper left first molar was moved for 21 days. Bone markers were administered 7 and 2 days before killing. Histological sections were cut at the coronal and apical levels. OUTCOME MEASURE: Alveolar socket area, periodontal ligament width, the relative extension of alveolar wall with erosion surfaces, and the mineralizing surfaces were measured and compared in the three groups. RESULTS: Alveolar socket, periodontal ligament width, and erosion surface were larger on the treated than on the control side in the three groups. The normal and hypothyroid groups showed a wider periodontal ligament at the bucco-distal site at the coronal level, while the hyperthyroid group showed a widening which was not spatially oriented. The normal and hyperthyroid groups showed higher erosion at the corono-mesial site. The mineralizing surfaces were larger on the treated than on the control side in the normal and hypothyroid groups, but not in the hyperthyroid group. CONCLUSION: In the hyperthyroid group, the widening of the periodontal ligament was not spatially oriented and the increased erosion was not accompanied by increased formation, as observed in the normal and hypothyroid groups.

Alveolar Process↗

PubMed2002

Cell proliferation and cell death in periodontal ligaments during orthodontic tooth movement.

The purpose of this study was to investigate cellular responses of periodontal ligaments during tooth movement. Twenty-eight male Sprague-Dawley rats, weighing 200-250 g each, were used. To create the orthodontic force, elastic rubber blocks (0.65 mm thick) were inserted between the maxillary first and second molars on both sides. On days 3, 7, 10, 14, 21 and 28 after rubber block insertion, histopathological changes in both the tension and the pressure sides were examined by immunohistochemistry using proliferating cell nuclear antigen (PCNA) and by the TUNEL method. The ratios of PCNA-positive cells on the tension side 3 and 7 days after rubber block insertion were higher than those on the pressure side. The ratios of PCNA-positive cells on the tension side were highest at day 3 after insertion and then decreased during the remainder of the experimental period. On the pressure side, the ratios of PCNA-positive cells increased up to day 10 post insertion, then decreased from 14 to 28 days. The ratios of TUNEL-positive cells on both the tension and the pressure sides increased throughout the entire experimental period. These results indicate that the periodontal ligaments on the tension side are able to respond more promptly to orthodontic forces than those on the pressure side. The data also suggest that the ratios of cell proliferation and of cell death are closely related to the regeneration and reconstruction of periodontal ligaments which reflect the orthodontic force.

Animals↗

PubMed2003

Orthodontic movement in traumatically intruded teeth: a case report.

Intrusive luxation of permanent mature teeth is one of the most serious injuries to the periodontal ligament in dental traumatology. Various treatment approaches are currently practised. The treatment of choice for traumatically intruded teeth was to combine orthodontic repositioning and endodontic treatment. This case report describes the treatment of a 50-year-old male patient, with four completely intruded mature permanent maxillary incisors. Orthodontic extrusion was initiated 1 week after the trauma. After 10 days, the crowns of the teeth were exposed to start endodontic therapy. Nine weeks after the injury and 8 weeks after the beginning of orthodontic extrusion, the intruded incisors were back about to their original position before the displacement occurred. All treatment management as well as a follow-up 8 years after the trauma are described.

Humans↗

PubMed2006

What is the most effective adhesive for attaching orthodontic bands?

DATA SOURCES: The Cochrane Oral Health Group's Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL), Medline and Embase were used and a search of the internet also undertaken. There was no restriction with regard to publication status or language of publication. STUDY SELECTION: Randomised controlled trials (RCT) and controlled clinical trials (CCT), including split-mouth studies, of adhesives used to attach orthodontic bands to molar teeth were selected. DATA EXTRACTION AND SYNTHESIS: All review authors were involved in study selection, validity assessment and data extraction without blinding to the authors, adhesives used or results obtained. All disagreements were resolved by discussion. RESULTS: Five RCT and three CCT were identified as meeting the review's inclusion criteria. All the included trials were of split-mouth design. Four trials compared chemically cured zinc phosphate and chemically cured glass ionomer; three trials compared chemically cured glass ionomer cement with light-cured compomer; one trial compared chemically cured glass ionomer with a chemically cured glass phosphonate. Data analysis was often inappropriate within the studies that did meet the inclusion criteria. CONCLUSIONS: There is insufficient evidence to determine the most effective adhesive for attaching orthodontic bands to molar teeth in patients with full-arch fixed orthodontic appliances.

Comment↗

PubMed2006

Local RANKL gene transfer to the periodontal tissue accelerates orthodontic tooth movement.

It has been reported that not only selective alveolar-bone resorption, but also receptor activator of nuclear factor kappa B ligand (RANKL) expression is induced on the compressed side of an orthodontically moving tooth. Numerous reports have described the pharmacological acceleration of tooth movement (TM) through the activation of osteoclasts. However, because of rapid flush out by blood circulation, daily systemic administration or daily local injection is needed. Previously, we discovered that every-3-days OPG gene transfer to the periodontal-tissue inhibited RANKL-mediated osteoclastogenesis and diminished experimental TM. Therefore, we hypothesized that local RANKL gene transfer into the periodontal tissue would accelerate TM. The upper first molars of 6-week-old male Wistar rats were moved palatally using fixed orthodontic wires. The inactivated hemagglutinating-virus of Japan (HVJ) envelope vector containing the mouse RANKL expression plasmid was injected periodically into the palatal periodontal tissue of the upper first molars during TM. Local RANKL gene transfer significantly enhanced RANKL expression and osteoclastogenesis in periodontal tissue without any systemic effects. The TM rate was significantly increased in the RANKL gene transfer side. In conclusion, we demonstrated that transfer of the RANKL gene to the periodontal-tissue activated osteoclastogenesis and accelerated the amount of experimental TM. Local RANKL gene transfer might be a useful tool not only for shortening orthodontic treatment, but also for moving ankylosed teeth where teeth, fuse to the surrounding bone.

Animals↗

PubMed1995

Correlation of orthodontic treatment demand with treatment need assessed using two indices.

The orthodontic treatment need of 105 first year university students (51 males and 54 females, mean age 19.75 years) at the University of Hong Kong was assessed using the Occlusal Index (OI) and the Index of Orthodontic Treatment Need (IOTN). The results were compared with the subjects' orthodontic treatment demand derived from a questionnaire. The OI assessment correlated better with the individuals' own perceptions of appearance than did the IOTN, and the treatment need indicated by the OI also correlated better with the individuals' actual treatment demands.

Adult↗