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PubMed1984

Temporomandibular disorders and functional occlusion after orthodontic treatment: results of two long-term studies.

The prevalence of temporomandibular (TM) disorders and the status of the functional occlusion in former orthodontic patients many years after treatment were evaluated in two independent clinical studies. In each study, the former orthodontic patients were compared to similar groups of adults with untreated Class I and Class II malocclusions. Both studies reported similar findings with regard to TM disorders; there was no statistically significant difference (p greater than 0.05) between the orthodontic and control groups in either study. The illinois study found a high prevalence of nonfunctional (balancing) contacts in both groups, while the Eastman study found a somewhat lower prevalence. Differences for most of the occlusal parameters between the orthodontic and control groups were not statistically significant in either study. The findings for these two studies are similar and suggest that orthodontic treatment performed during adolescence does not generally increase or decrease the risk of developing TM disorders in later life.

Adult↗
PubMed1996

Vascular changes in the periodontal ligament after removal of orthodontic forces.

Vascular changes in the periodontal ligament after release of orthodontic force and their possible contribution to relapse of relocated teeth are poorly understood. This study documented the periodontal vascular changes after 2 weeks of tooth movement and during a 3-week period after release of orthodontic force. This study is the first comprehensive quantitative description of these events. Changes in blood vessel number and density were correlated with the direction of tooth movement (initially mesial in response to force but later distal because of relapse). Application and removal of orthodontic force produced significant changes in blood vessel number and density, which were not related to changes in tissue volume. The vascular changes were dependent on the site of evaluation and the size of the blood vessel. The periodontal vascular distribution and density can be summarized as follows: (1) increased after application of orthodontic force, (2) transient decrease subsequent to removal of force, (3) transient increase during reactivated distal drift, and (4) normalization. Normalization was achieved during an interval equivalent to the duration of orthodontic force, suggesting that the vasculature could modulate interstitial tissue pressures, resulting in relapse of relocated teeth. The role of the periodontal vasculature in alveolar remodeling and in modifying interstitial tissue fluid pressures coincident to human tooth movement requires further study.

Alveolar Process↗
PubMed1986

Abnormal function of the temporomandibular joints and related musculature. Orthodontic implications. Part II.

Timing of mandibular growth and orthodontic treatment are coincidental, not cause-and-effect. Comparison of cephalometric radiographic tracings made before, during, and after treatment has shown no evidence that orthodontic forces can either arrest or stimulate growth of the condyle. Conversely, the growth behavior of the condyles can have a profound effect on the time required to achieve an orthodontic correction and on the anatomic and functional relationships at the end of treatment and later. Mandibular growth at the moment of orthodontic force application can have important effects on facial growth and function. If there is no growth, the mandible may rotate downward and backward, and condyle displacement and clicking can occur. Future growth rarely leads to recovery of such alterations. With adequate growth at the moment of orthodontic force application, the freeway space is maintained and horizontal tooth movement does not alter mandibular position. The position of the maxillary incisors in the face must be based on many considerations going far beyond arbitrary conformity to some "standard" values based on averages. Functional relationships and their effects on the joints are one of those considerations, along with esthetics. Dynamic thinking requires that maxillary incisors not be over-retracted, anticipating continued growth of the condyle that can reposition the body of the mandible and lower incisors downward and forward. This can occur before, during, or many years after treatment. If a tight incisor relationship is established, or develops naturally, in the early or midteens, and the condyles later outgrow the maxilla, clicking may well develop. Anterior translation of the mandible with the new growth is impeded by the incisors, so posterior displacement of the condyles occurs instead. This is most likely to occur in straight ("good") faces. Facial morphology, or pattern, has an impact on function. In the straight facial pattern, these problems usually involve incisor interference. In convex faces, the problems more often involve vertical molar interferences. Each of these presents its own unique problems and treatment requirements.

Adolescent↗
PubMed2001

Growth hormone receptor and IGF-I receptor immunoreactivity during orthodontic tooth movement in the prednisolone-treated rat.

Bone remodeling during tooth movement is regulated by local and systemic factors. Two regulators of bone metabolism are growth hormone (GH) and insulin-like growth factor-I (IGF-I). Their effects are mediated via binding to GH receptor (GHR) and IGF-I receptor (IGF-IR) in target tissues. Corticosteroids may affect the activity of these growth factors. This study examined the effect of prednisolone on GHR and IGF-IR expression in dental tissues following orthodontic tooth movement. The corticosteroid-treated group (N = 6) was administered prednisolone (1 mg/kg) daily and the control group (N = 6) received equivalent volumes of saline. An orthodontic force (30 g) was applied to the maxillary first molar. Animals were sacrificed 12 days postappliance insertion. Sagittal sections of the first molar were stained for GHR and IGF-IR immunoreactivity. GHR and IGF-IR cell counts were elevated following appliance-treatment. Orthodontic tooth movement appeared to up-regulate GHR and IGF-IR immunoreactivity, but this up-regulation was reduced following prednisolone treatment. The suppression of GHR and IGF-I immunoreactivity in steroid-treated animals infers the mechanism whereby bone resorption and deposition, necessary for orthodontic tooth movement, may be inhibited by prednisolone. However, at 12 days postappliance insertion, no difference in orthodontic tooth movement was observed following low-dose prednisolone treatment.

Alveolar Process↗
PubMed2003

Optimum force magnitude for orthodontic tooth movement: a systematic literature review.

The aim of this study was to perform a meta-analysis of the literature concerning the optimal force or range of forces for orthodontic tooth movement. Over 400 articles both on human research and animal experiments were found in Medline and by hand searching of main orthodontic and dental journals. Articles on animal experiments were in the majority. A wide range of animal species such as rat, cat, rabbit, beagle dog, monkey, mouse, and guinea pig were used. Besides variation in species, there was also a wide range of force magnitudes, teeth under study, directions of tooth movement, duration of experimental period, and force reactivation. Furthermore, hardly any experiments were reported that provide information on the relation between the velocity of tooth movement and the magnitude of the applied force. Data from human research on the efficiency of orthodontic tooth movement appeared to be very limited. The large variation in data from current literature made it impossible to perform a meta-analysis. Therefore, we have systematically reviewed the literature. It appeared that no evidence about the optimal force level in orthodontics could be extracted from literature. Well-controlled clinical studies and more standardized animal experiments in the orthodontic field are required to provide more insight into the relation between the applied force and the rate of tooth movement.

Animals↗
PubMed2004

Effects of PGI2 and TxA2 analogs and inhibitors in orthodontic tooth movement.

This study evaluates the effects of prostacyclin (PGI2) and thromboxane A2 (TxA2) in orthodontic tooth movement and osteoclastic activity in rats. The study sample consisted of 150 male Sprague-Dawley rats. The rats were randomly divided into five equal groups, and each group was again equally divided into three subgroups (SGs). Twenty grams of reciprocal force was applied to maxillary incisors of the rats with a spring bent from 0.35 mm stainless steel wire, except for the rats in the last SG. Iloprost (PGI2 analog), indomethacin (PGI2 inhibitor), U 46619 (TxA2 analog), and imidazole (TxA2 inhibitor) were dissolved in 0.9% NaCl (saline solution), and each material was prepared in three different concentrations (10(-4), 10(-5), and 10(-6) M/L). Iloprost was administered (20 microL/12 hours) in the first three SGs with the sequence of 10(-4), 10(-5), and 10(-6) M/L. Indomethacin, U 46619, and imidazole were administered in the next nine SGs with the same sequence and dose. In SG 13, 0.9% NaCl solution was administered (20 microL/ 12 hours) to the rats together with orthodontic force. Only orthodontic force was not used in SG 14, and neither any solution nor orthodontic force was used in the last SG. The rats were sacrificed on the fifth day of the experiment, premaxillae were dissected, and cross samples were taken. The results showed that PGI2 and TxA2 analogs increased the number of multinuclear osteoclasts, osteoclastic bone resorption, and rate of orthodontic tooth movement.

15-Hydroxy-11 alpha,9 alpha-(epoxymethano)prosta-5↗
PubMed2001

A comparison of the reliability and validity of 3 occlusal indexes of orthodontic treatment need.

Several occlusal indexes are currently used to ascertain eligibility for orthodontic treatment. A comparison of 3 indexes of orthodontic treatment need was made with the consensus opinion of a panel of 15 experienced orthodontists. Sets of study casts (170) representing the full spectrum of malocclusions were selected. An examiner, calibrated in the Dental Aesthetic Index, the Handicapping Labiolingual Deviation with the California Modification, and the Index of Orthodontic Treatment Need, scored the casts. The panel of orthodontists individually rated the same casts for their degree of orthodontic treatment need. The mean rating of the panel on the need for treatment was used as the gold standard for evaluating the validity of the indexes. Intrarater and interrater reliability was high (kappa > 0.8). Overall accuracy of the indexes, as reflected in area under receiver-operating characteristic curves, was also high: Dental Aesthetic Index, 95%; Handicapping Labiolingual Deviation with the California Modification, 94%; and Index of Orthodontic Treatment Need, 98%. Cutoff points for the indexes that resulted in the closest agreement with the gold standard differed from the published cutoff points for the indexes. The indexes appear to be valid measures of treatment need as perceived by orthodontists. The published cutoff points for the indexes were more conservative in assigning patients for treatment than a panel of orthodontists. However, adjusting the cutoff points moved all 3 indexes into close agreement with the experts.

California↗
PubMed1991

The efficacy of two-stage titanium implants as orthodontic anchorage in the preprosthodontic correction of third molars in adults--a report of three cases.

Orthodontic movement of teeth is often required to satisfactorily treat a variety of oral rehabilitation problems. Considerable limitations in the clinical application of orthodontic treatment may result from the lack of teeth suitable for anchorage. Three patients with edentulous posterior segments are presented illustrating how implants can be utilized for preprosthodontic correction of impacted third molars rendering them suitable as bridge abutments. The patients have been followed for 8-10 years. Two-stage titanium implants were used as orthodontic anchorage as no dental anchorage was available. Edgewise orthodontic mechanics were used to move the third molars mesially with forces up to 2.5 N (about 250 g). No movement of the implants occurred and they were radiologically and clinically intact at the end of the orthodontic loading and were, therefore, subsequently used as bridge abutments.

Adolescent↗
PubMed1996

The hyaline zone and associated root surface changes in experimental orthodontics in rats: a light and scanning electron microscope study.

Light and scanning electron microscopic (SEM) examinations were used to study the hyaline zone and associated root resorption after orthodontic treatment of the upper first molars of rats. The orthodontic treatment consisted of a fixed buccal expansion appliance with an initial force of 250 mN. The animals were divided into nine experimental groups with orthodontic treatment and one control group without orthodontic treatment. Three groups were sacrificed immediately after 1, 3, and 7 days of treatment, and six groups after 7 days of treatment followed by 1, 2, 3, 4, 5, and 6 weeks without treatment. A hyaline zone on the pressure side of the mesial root was identified at the light microscopic level of examination as well as the SEM examination as early as 1 day after the initiation of treatment. In the SEM it was found that on the roots of teeth studied in the first few days after initiation of treatment the hyaline tissue was so firmly attached to the root that it remained in place during the extraction and preparation procedures. After longer treatment periods these hyaline zones were lost at extraction or during the preparation for the SEM examination. The cementum surface under the hyaline zone had a smooth appearance suggesting that the surface had been modified by substances released from the hyaline zone. After 1 week of treatment, resorption in the cementum could be noticed. The resorption extended to the dentine as uncovered dentinal tubuli were found. Formation of reparative cementum started two weeks after treatment. Changes in the cementum surface as well as root resorption cavities could be seen for as long as 6 weeks after the cessation of orthodontic treatment.

Activator Appliances↗
PubMed1998

Enhanced angiogenesis induced by diffusible angiogenic growth factors released from human dental pulp explants of orthodontically moved teeth.

The aim of this study was to determine if diffusible angiogenic growth factors were released in human dental pulp during orthodontic tooth movement. These factors, if diffusible, could induce angiogenesis in other tissues, and may then be isolated and identified. The pulps from 14 premolar teeth treated with straight wire fixed orthodontic appliances for 2 weeks were compared with those of 14 untreated control premolar teeth from the same subjects. Following tooth extraction and sectioning, 1-mm horizontal sections of pulp tissue were embedded in collagen with 1-mm sections of rat aorta and co-cultured in growth media for up to 4 weeks. Sections of rat aorta alone were also cultured. Angiogenic changes in the form of microvessel growth were observed by light microscopy. Microvessel identification was confirmed by electron microscopy and by immunohistochemistry using staining for factor VIII-related antigen marker for endothelial cells. When compared at days 5, 10, and 14 of co-culture, the number of microvessels was significantly greater in the pulps from orthodontically moved teeth than in those from the control teeth. The number of rat aorta microvessels was also significantly greater when co-cultured with pulp from orthodontically moved teeth than with pulp from control teeth and when compared with control cultures of rat aorta alone. There were no significant differences in microvessel numbers between the rat aorta co-cultured with pulp from control teeth and control cultures of rat aorta alone. These results indicate an increase in angiogenic growth factors in the pulp of orthodontically moved teeth, and the enhanced response of the rat aorta when co-cultured with this pulp shows that these factors appear to be diffusible.

Adolescent↗
PubMed2005

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

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.

Adult↗
PubMed2002

Internal root resorption associated with inadequate caries removal and orthodontic therapy.

This case report presents a case of internal root resorption originating from inadequate caries removal and orthodontic therapy in maxillary right lateral incisor in a 13-yr-old female. A preoperative, panoramic radiograph taken at the orthodontic office showed no evidence of resorption, however, the composite restoration in the coronal portion was inadequate. During 4 months of nickel titanium orthodontic wire activation, the patient suffered spontaneous pain. Periapical radiographs revealed internal root resorption in the middle third of the root. Endodontic treatment was accomplished and coronal restorations were completed with composite resin. Periodical radiograph examination as well as orthodontic treatment was continued. The tooth was clinically and radiographically healthy at the 18-month follow-up. The importance of the preoperative radiographic examination as well as radiographs during orthodontic treatment is affirmed.

Adolescent↗
PubMed1991

Periodontal tissue reactions to orthodontic extrusion. An experimental study in the dog.

Orthodontic tooth extrusion is used at crown lengthening procedures or in conjunction with periodontal therapy aimed at eliminating or reducing angular bone defects. A technique for orthodontic extrusion combined with resection of the supracrestal attachment fibers (fiberotomy) was recently proposed as an adjunct to certain restorative procedures. The aim of the present investigation was to analyze reactions of the periodontal tissues to orthodontic extrusion when combined with fiberotomy. In 5 beagle dogs, the mesial roots of the 2nd, 3rd and 4th hemisected mandibular premolar were used as target roots while the distal roots served as reference units. After a baseline examination, an orthodontic extrusion device (stent) was installed and reactivated at 2-week intervals during an 8-week period of active tooth movement. Immediately following the installation of the stent and once every 2nd week, the target roots were exposed to fiberotomy. After the active period, the teeth were retained in their new position for a period of 8 weeks. Clinical, radiographical and histological measurements were performed. The results from the investigation demonstrated that orthodontic extrusion combined with supracrestal fiberotomy resulted in a coronal displacement of the tooth and was associated with pronounced recession of the gingival margin and extensive loss of connective tissue attachment. The degree of gingival recession and the amount of loss of connective tissue attachment were, however, less extensive than the amount of tooth extrusion. Thus, repeated fiberotomy obviously failed to entirely prevent coronal migration of the attachment apparatus. It was also observed that undesired attachment loss had occurred at the reference roots.

Animals↗
PubMed2005

Bone response to different strength orthodontic forces in animals with periodontitis.

BACKGROUND: Occlusal alterations resulting from tooth movements caused by periodontitis-related bone loss are often corrected with orthodontic treatments. Although the outcome is usually satisfactory, a quantitative histomorphometric study of bone response would contribute to improving treatment planning and optimizing results. METHODS AND RESULTS: This study is a histomorphometric analysis of alveolar bone response to 51 and 75-g orthodontic forces applied to rat molars subjected to experimental periodontitis by placing a ligature around the neck of the molar during 48 h. The orthodontic device consisted of two bands with a tube welded to their palatine aspect, through which the arms of a helicoidal spring were threaded so as to exert force toward palatine. The device was placed immediately and 48 h after removing the ligatures. When applied 48 h post-removal of the ligature, both orthodontic forces caused an increase in bone volume in the periodontitis group. CONCLUSIONS: Our study shows that application of orthodontic forces once periodontal infection has been controlled contributes to increasing alveolar bone volume, consequently improving bone quality.

Alveolar Bone Loss↗
PubMed2004

Tissue reaction to orthodontic tooth movement in acute and chronic corticosteroid treatment.

OBJECTIVES: To study tissue reaction to orthodontic loading during the course of short- and long-term corticosteroid administration. DESIGN: 'Split-mouth' design to perform orthodontic tooth movement in 64 six-month-old male rats divided into groups: no drug administration (n = 19), acute (n = 22) and chronic (n = 23) 8 mg/kg/day corticosteroid treatment. Performed in the Department of Orthodontics at Aarhus University. EXPERIMENTAL VARIABLE: The upper left first molar was moved for 21 days. Bone markers were administered at 7 and 2 days before sacrifice. Histological sections were cut at the coronal level. OUTCOME MEASURE: Tooth movement rate, alveolar socket area, the relative extension of alveolar wall with erosion, and the mineralizing surfaces were measured and compared in the three groups. RESULTS: Tooth movement rate increased in the chronic group. The mechanical load induced an enlargement of the alveolar wall that was less pronounced in both medicated groups. In the acute group the drug suppressed bone resorption and formation without mechanical stimulus. Force application resulted in significant increase in the relative extension of resorption and formation in both drug groups; it was particularly pronounced in the chronic group. CONCLUSION: Because acute corticosteroid ingestion reduces bone turnover, in these patients orthodontic treatment might best be postponed until a time the patient is free of the drug. Chronic steroid ingestion leads to an increased biological reaction to mechanical perturbation indicating that the orthodontic force level should be reduced and controlled more frequently in patients on chronic steroid treatment.

Alveolar Bone Loss↗
PubMed1996

Angiogenesis in human dental pulp following orthodontic tooth movement.

The pulpal response to orthodontic force is thought to involve cell damage, inflammation, and wound healing. These situations are likely to be associated with the release of angiogenic growth factors. We therefore investigated human dental pulps to determine if angiogenic changes could be detected after orthodontic force application. Fifteen premolar teeth were treated with straight-wire fixed orthodontic appliances for two weeks, and comparisons were made with 15 untreated control premolar teeth from the same subjects. The teeth were extracted and sectioned. The pulps were removed, divided into 1-mm sections, embedded in collagen, and cultured in growth media for up to four weeks. Cultures were examined daily, by light microscopy, for growth and number of microvessels. Apparent microvessels were observed within five days. Confirmation of microvessel identification was by electron microscopy for endothelial cell morphology. There were significantly greater numbers of microvessels at day five and day ten of culture in the pulp explants from orthodontically treated teeth compared with those from the pulps of control teeth. These results are consistent with the hypothesis that there is an increase in angiogenic growth factors in the pulp of orthodontically moved teeth.

Angiogenesis Inducing Agents↗
PubMed2003

The in vivo levels of matrix metalloproteinase-1 and -8 in gingival crevicular fluid during initial orthodontic tooth movement.

Orthodontic force induces biochemical responses in the periodontal ligament (PDL), but the matrix metalloproteinase (MMP)-dependent molecular mechanisms in orthodontically induced periodontal remodeling have remained unclear. Previous studies indicate that mechanical stress induces MMP-1 production in human PDL cells in vitro. We tested the hypothesis whether the in vivo levels, molecular forms, and degree of activation of MMP-1 and MMP-8 in gingival crevicular fluid (GCF) reflect an early stage of orthodontic tooth movement. Molecular forms of MMP-1 and MMP-8 were analyzed by Western blot, and MMP-8 levels by quantitative immunofluorometric assay (IFMA). The results showed that GCF MMP-8 levels for orthodontically treated teeth were significantly higher at 4-8 hrs after force application than before activation, and when compared with the control teeth (p < 0.05). Analysis of our data indicates that the cells within the periodontium are up-regulated to produce MMP-8, and the increased expression and activation of GCF MMP-8 reflect enhanced periodontal remodeling induced by orthodontic force.

Adolescent↗
PubMed2004

GENETIC FACTORS IN EXTERNAL APICAL ROOT RESORPTION AND ORTHODONTIC TREATMENT.

External apical root resorption (EARR) is a common sequela of orthodontic treatment, although it may also occur in the absence of orthodontic treatment. The degree and severity of EARR associated with orthodontic treatment are multifactorial, involving host and environmental factors. Genetic factors account for at least 50% of the variation in EARR. Variation in the Interleukin 1 beta gene in orthodontically treated individuals accounts for 15% of the variation in EARR. Historical and contemporary evidence implicates injury to the periodontal ligament and supporting structures at the site of root compression following the application of orthodontic force as the earliest event leading to EARR. Decreased IL-1beta production in the case of IL-1B (+3953) allele 1 may result in relatively less catabolic bone modeling (resorption) at the cortical bone interface with the PDL, which may result in prolonged stress concentrated in the root of the tooth, triggering a cascade of fatigue-related events leading to root resorption. One mechanism of action for EARR may be mediated through impairment of alveolar resorption, resulting in prolonged stress and strain of the adjacent tooth root due to dynamic functional loads. Future estimation of susceptibility to EARR will likely require the analysis of a suite of genes, root morphology, skeleto-dental values, and the treatment method to be used-or essentially the amount of tooth movement planned for treatment.

Journal Article↗