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At least 1,099 records · Page 61Linked to original sources
PubMed2003

Age effect on orthodontic tooth movement in rats.

Orthodontic procedures seem to be more time-consuming in adults than in juveniles. This might be related to delay in the initial tissue response or to a slower turnover of the bone and periodontal ligament in adults. To study this problem, we studied orthodontic tooth movement in two groups of 30 rats, aged 6 wks and 9-12 mos, respectively. At one side of the maxilla, 3 molars together were moved mesially with a standardized orthodontic appliance delivering a force of 10 cN. The other side served as a control. The results showed a faster initial tooth movement in juvenile than in adult animals. However, once tooth movement had reached the linear phase, the rate of tooth movement was the same in both groups. The results indicate that, besides a delay in the onset of tooth movement in adult animals, tooth movement could be equally efficient in adults once it had started.

Aging↗
PubMed2000

[Developments in fixed orthodontic appliances].

The Edgewise system and the Begg technique were until the early 1970's two of the most familiar and well-known fixed appliance techniques in orthodontics. During the following years they both underwent some slight adaptations that were generally based on more straightforward biomechanics. These changes have led to what in recent years is called the 'Straight Wire technique'. The latter claims to be the treatment option of choice based on preadjusted appliances and preformed arch wires. Besides biomechanics, treatment tools also concentrated on esthetics. It resulted in the development of smaller brackets as well as tooth coloured ones made from polycarbonates or ceramics. Finally lingual orthodontics starts to play a more important role in the orthodontic treatment options for the new millennium.

Biomechanical Phenomena↗
PubMed2005

Management of hypodontia: orthodontic considerations (II).

Patients with congenitally missing teeth (hypodontia) present with complex problems. Meeting their treatment needs requires a joint effort between the disciplines of orthodontics and restorative dentistry. There are a number of options available to restore space generated by missing teeth. In the majority of patients orthodontic treatment will be required before this space can be restored satisfactorily. The second part of this series reviews the orthodontic considerations for various options.

Anodontia↗
PubMed2005

Orthodontic space maintenance--a review of current concepts and methods.

Crowding and a lack of space in the permanent dentition are amongst the most common orthodontic problems encountered in orthodontic patients. Often the aetiology of these problems is linked to premature loss of one or more deciduous teeth with corresponding loss of space. Many of these cases could have been prevented or their severity alleviated if the practitioner employed adequate planning and space maintenance during initial treatment in the mixed dentition. A review of some of the current orthodontic space maintenance appliances and their indications is presented along with a table to aid the practitioner in treatment planning.

Age Factors↗
PubMed1998

Pain-free and mobility-free orthodontics?

Pain-free and mobility-free orthodontics are not discussed often, although they obviously would be significant advances and very desirable practice-builders. These advantages have occasionally been reported in the orthodontic literature by different authors who used magnetic force fields for molar distalization, aiding tooth eruption, etc., and are presented here in Group I. Group II discusses several different possible mechanisms of action, including among others, an accelerated osteogenic rate and a sensory neuron action potential blockade. All the available evidence seems to confirm that pain-free and mobility-free orthodontics is a real phenomenon.

Animals↗
PubMed1991

[Orthodontic measuring and simulating systems (OMSS) for the static and dynamic analysis of tooth movement].

An orthodontic measurement and simulation system (OMSS) is presented. The major components of this system are two measuring tables each comprising a force/torque sensor and a motor driven, fully three-dimensionally adjustable positioning stage. The force/torque sensors are capable of measuring simultaneously all forces and torques acting on a tooth. Using the computer program "OMSS" which runs on a personal computer, several different measurements can be conducted. On the one hand, the system supports absolute measurements such as the registration of a force/deflection diagram. Furthermore, even multidimensional force/deflection- or torque/distance curves can be measured. On the other hand, simulations of orthodontic tooth movement can be conducted. In such simulations, the force system acting on a tooth is measured and the resulting tooth movements are calculated. By using this "computer typodont", not only the static but the dynamic behaviour of orthodontic appliances can be studied. The application of this system is demonstrated by the analysis of several orthodontic problems.

Computer Simulation↗
PubMed2005

Devastating endophthalmitis following penetrating ocular injury during night sleep from orthodontic headgear: case report and literature review.

BACKGROUND: Complications associated with the use of extra-oral traction devices (orthodontic headgear or facebow) including facial and ocular injuries, are considered infrequent. METHODS: We describe the case of a 12-year-old boy who was inadvertently injured by the metallic bow of orthodontic headgear during sleep and developed blinding intra-ocular infection (endophthalmitis). RESULTS: The injury resulted in corneal perforation. Visual acuity at presentation was 20/60 but deteriorated rapidly to light perception despite prompt medical and surgical treatment for endophathalmitis. Sympathetic ophthalmia developed and was controlled with systemic corticosteroids and imuran. Bacterial cultures showed mixed infection by gram-negative bacilli and Streptococcus viridans. In 10 (91%) out of the 11 eyes that were reported including our case, the visual acuity was hand movement perception or less. CONCLUSIONS: The increase in case reports of such injuries should prompt the establishment of a standard policy regarding the use of orthodontic headgear and increase awareness of orthodontists and ophthalmologists to the blinding potential of even trivial and minor ocular injuries by orthodontic headgear. Intervention should be one step ahead compared with ocular injuries from other foreign bodies.

Adolescent↗
PubMed2006

Expression of genes for gelatinases and tissue inhibitors of metalloproteinases in periodontal tissues during orthodontic tooth movement.

Orthodontic tooth movement progresses by a combination of periodontal ligament (PDL) tissue and alveolar bone remodeling processes. Besides the remodeling of alveolar bone around the moving teeth, the major extracellular matrix (ECM) components of PDLs, collagens, are degenerated, degraded, and restructured. Matrix metalloproteinases (MMPs) and their specific inhibitors, tissue inhibitors of metalloproteinases (TIMPs), act in a co-ordinated fashion to regulate the remodeling of periodontal tissues. We hypothesized that the expression levels of the genes for MMP-2, MMP-9, and TIMPs 1-3 are increased transiently in the periodontal tissue during orthodontic tooth movement. To test this hypothesis, we employed an animal model of tooth movement using rats, as well as in situ hybridization to analyze the expression levels of Mmp-2, Mmp-9, and Timps 1-3. The expression levels of these genes increased transiently in cells of periodontal tissues, which include cementoblasts, fibroblasts, osteoblasts, and osteoclasts, at the compression side of the moving teeth. The transient increases in gene expression at the tension side were mainly limited to osteoblasts and cementoblasts. In conclusion, the expression levels of Mmp-2, Mmp-9, and Timps 1-3 increase transiently during orthodontic tooth movement at both the tension and compression sides. The expression of these genes is regulated differentially in the periodontal tissue of the tension side and compression side. This altered pattern of gene expression may determine the rate and extent of remodeling of the collagenous ECM in periodontal tissues during orthodontic tooth movement.

Animals↗
PubMed1976

Reconstitution of the human oxytalan system during orthodontic tooth movement.

Orthodontic tooth movement in man has revealed that the oxytalan fiber system possesses a high order of maintenance. Oxytalan fibers did not merely increase in number during orthodontic movement. On the contrary, the oxytalan fiber system underwent reconstruction and adaptation to extensive metabolic and anatomic changes within the periodontium. With the use of light orthodontic forces, the oxytalan fiber system was constantly remodeled on both the tension and compression sides and maintained a characteristic cementum-vascular relationship even when teeth were moved a significant distance through the alveolar bone. In contrast, heavier forces caused localized destruction of the oxytalan system in regions of excessive pressure and tension. Reconstitution of the oxytalan system provided evidence against the concept that oxytalan fibers are stretched by orthodontic movement and subsequently contribute to relapse by elastic rebound. In man the oxytalan fiber system of the periodontal ligament is arranged as a three-dimensional fiber meshwork and exhibits a complex geometry like other fiber systems in the connective tissues. Knowledge of the interaction between elastic and collagen fibrillar assemblies has been used to derive some speculative concepts of oxytalan-collagen interaction. These concepts have been put forward with the intention of stimulating further interest in the oxytalan fiber meshwork. The present investigation emphasizes that the use of the light microscope to examine and record static images of complex biologic changes can provide new knowledge of the structure and function of human connective tissues.

Adolescent↗
PubMed1978

Surgical-orthodontic correction of vertical maxillary excess.

Superior repositioning of the maxilla via maxillary ostectomy has proved to be useful method of treating patients with vertical maxillary excess. It is indicated primarily in patients with lip incompetence, excessive exposure of maxillary anterior teeth, long lower facial height, contour-deficient chin, and either Class I or Class II malocclusion. We have used this procedure as routine treatment for vertical maxillary excess over the past 5 years. Timing of the surgery is not so important in non-open-bite patients, and the procedure can be done with equal success before any orthodontic intervention, during orthodontic treatment, and following all orthodontic procedures. Timing is primarily dependent upon the orthodontist's desires. Since the surgery can produce a much simpler orthodontic problem, thus reducing treatment time and allowing a better over-all result, we recommend that it be done as early in treatment as possible. Clinically, the over-all improvement in facial appearance and the predictability and stability of the results have made this a most versatile and effective procedure when carried out with good planning, proper execution and attention to detail.

Adolescent↗
PubMed1979

Frequency of tooth extraction in orthodontic treatment.

Orthodontic extraction frequency describes the percentage of an orthodontic patient population experiencing extractions of one or more permanent teeth, excluding third molars. It is a useful statistical measure of the many variables associated with the extraction-nonextraction decision. For a study sample of 537 North American white orthodontic patients, the frequency of tooth extraction was determined as 42.1 percent. This is compared with a range of 6.5 percent to 83.5 percent reported in the world dental literature. Factors responsible for the enormous differences in orthodontic extraction frequency are explored. The study of extraction frequency offers a simple, valuable aid for the clinician to understand better the nature of his patient population, his treatment methods, and his rationalizations.

Adolescent↗
PubMed1980

Electric currents, bone remodeling, and orthodontic tooth movement. II. Increase in rate of tooth movement and periodontal cyclic nucleotide levels by combined force and electric current.

Piezoelectric currents in mechanically stressed bone were implicated in the activation of bone cells. The objectives of this experiment were to determine the usefulness of exogenous electric currents in accelerating orthodontic tooth movement and to study the effect of electric-orthodontic treatment on periodontal cyclic nucleotides. Maxillary canines were tipped in five cats by 80 g force. Two groups of five cats each were treated by an electric-orthodontic procedure to one maxillary canine for 7 and 14 days, respectively. Teeth treated by force and electricity moved significantly faster than those treated by force alone. Enhanced bone resorption was observed near the anode (PDL compression site), while bone formation was pronounced near the cathode (PDL tension site). Staining for cyclic nucleotides was increased when electric stimulation was added to the mechanical force. These results suggest that orthodontic tooth movement may be accelerated by the use of locally applied electric currents.

Alveolar Process↗
PubMed1986

The effect of indomethacin (an aspirin-like drug) on the rate of orthodontic tooth movement.

Prostaglandins (PGs) have been suggested as mediators of bone resorption. In addition, their presence in the periodontal tissues has also been demonstrated. To characterize the involvement of PGs in orthodontic tooth movement, indomethacin, an aspirin-like drug and a potent inhibitor of PG synthesis, was administered orally to six mongrel cats; another group of six animals served as controls. These animals were fitted with orthodontic appliances that consisted of coil springs stretching between the right side maxillary and mandibular canines and third premolars. The data for tooth-movement measurements were analyzed by repeated measures factorial analysis of variance. At the end of the 21-day experimental period, the rate of tooth movement in experimental animals was approximately one half of controls (P less than 0.01). Findings of this study imply a significant role for PGs in bone resorption during orthodontic therapy. It is recommended that aspirin-like drugs not be administered to patients undergoing orthodontic tooth movement as it may extend the treatment time.

Alveolar Process↗
PubMed1986

Effects of diazepam on orthodontic tooth movement and alveolar bone cAMP levels in cats.

Cyclic AMP has been suggested as a possible intracellular mediator in bone remodeling during tooth movement. Accordingly, an increase in the level of this nucleotide should result in faster tooth movement. Breakdown of cAMP was inhibited by administration of diazepam in eight cats undergoing orthodontic tooth movement; another matched group of eight animals served as controls. Orthodontic appliances consisted of coil springs stretching between the right side maxillary and mandibular canines and third premolars. The data for tooth movement and cAMP concentrations were analyzed by repeated measures factorial analyses of variance. The results indicated that administration of diazepam increased the rate of tooth movement at P less than 0.0005 and, interestingly, although diazepam had no effect on undisturbed tissues, it lowered the cAMP levels in the periodontal tissues of orthodontically moved teeth at P less than 0.01. On the basis of these results, it was concluded that the concentration of cAMP did not correlate with bone remodeling in this model and perhaps should not be used as an index of periodontal-tissue response during orthodontic tooth movement.

Alveolar Process↗
PubMed1988

Effect of orthodontic force on periodontal tissue metabolism. A histologic and biochemical study in normal and hypocalcemic young rats.

The relationship between force and degradation activity after application of orthodontic force is still obscure. Of particular clinical interest are the etiologic factors behind excessive root resorptions appearing in connection with orthodontic movement of teeth that has been proposed to be influenced by systemic factors regulating the tissue-degrading activity in periodontal tissues. Thus, the aim was, by histologic and new biochemical methods, to investigate the effect of orthodontic forces on the periodontal tissues in the normal and the hypocalcemic situation with secondary hyperparathyroidism. Root resorptions were induced in upper incisors of normal and hypocalcemic rats by subjecting the teeth to a moderate orthodontic force. In both groups the resorption of the roots occurred consistently in the vicinity of reorganizing areas of the periodontal ligament (PDL) with ongoing degradative activities and alveolar bone resorption. Furthermore, specific cell metabolic changes in alveolar bone and PDL in tension and pressure zones were detected and quantified by biochemical determination of alkaline phosphatase activity. This biochemical quantification of the metabolic changes together with the morphologic observations gave the clinically valuable information that the observed increase in occurrence and severity of root resorptions in moderate hypocalcemia was related to an increase in alveolar bone turnover. This study has shown that root resorptions were clearly related to the degradation process occurring in the vicinity of the hyaline zone and that in the hypocalcemic situation, the increase in root resorptions was related to an enhanced alveolar bone resorption. Thus, factors that minimize the time for resorptive/degradative activity should be discussed in this context rather than force per se.

Alkaline Phosphatase↗
PubMed1989

Internal derangement of the TMJ: changes associated with mandibular repositioning and orthodontic therapy.

Because of its apparent success in relieving symptoms, especially pain, anterior mandibular repositioning therapy is a popular mode of nonsurgical treatment for patients with painful, clicking internal derangement of the temporomandibular joint. Posterior open bites are a frequent consequence of such therapy and may necessitate either continued appliance wear or closure by equilibration, prosthetics, or orthodontics. The anatomic and functional changes that occur subsequent to mandibular repositioning during orthodontic closure of the posterior open bite are not well understood. A case of a patient with a Class II, deep bite malocclusion and painful internal derangement of the TMJ is presented. Transcranial and cephalometric radiographs, arthrograms, and mandibular movement recordings were obtained before treatment and after both repositioning therapy and orthodontic treatment. Regarding occlusal improvement and pain relief, the treatment was successful. However, not all of the changes that occurred during repositioning therapy were maintained after orthodontic treatment. The strategy used in this case (mandibular repositioning/orthodontic finishing) was evaluated by an examination of these anatomic and functional changes with a discussion centered on the possible mechanisms involved.

Adolescent↗
PubMed2004

Repair of orthodontically induced root resorption by ultrasound in humans.

Root resorption is an adverse outcome of orthodontic tooth movement. In addition to the iatrogenic response and compromising the crown-root ratio, root resorption has led to increased malpractice litigation against orthodontists. A clinically acceptable method of treating root resorption has not been validated in the literature to date. Previous research has shown that low-intensity pulsed ultrasound (LIPUS) can enhance healing of various types of traumatized connective tissues and stimulate dental tissue formation. The purpose of this study was to evaluate the effect of LIPUS on the healing process of orthodontically induced tooth-root resorption in humans. Twelve orthodontic patients who were seeking orthodontic treatment that necessitated extracting the first premolars before mechanotherapy participated in this study. For each patient, buccally activated springs were used to tip the maxillary first premolars buccally, with an initial force level of 50 g; the springs were checked weekly to ensure continuous force levels. A short period of LIPUS was applied to 1 side of each patient's mouth, with the other side used as a control. After 4 weeks, the experimental premolars of all patients were extracted, and the premolars of 6 patients were studied by scanning electron microscopy (SEM); the premolars of the other 6 patients were studied histologically. The number and total area of resorption lacunae as examined by SEM were compared between the LIPUS-treated and the control premolars with a t test. The SEM study showed a statistically significant decrease in the areas of resorption and the number of resorption lacunae in the LIPUS-exposed premolars. Histologic examination showed healing of the resorbed root surface by hypercementosis. The results of this study provide a noninvasive method for reducing root resorption in humans.

Bicuspid↗
PubMed2005

Alkaline phosphatase activity in dental pulp of orthodontically treated teeth.

INTRODUCTION: The aim of this study was to examine alkaline phosphatase (ALP) activity in the dental pulp of orthodontically treated teeth. METHODS: Sixteen healthy subjects (mean age 17.0 +/-1.6 years) who required extraction of 4 first premolars for orthodontic reasons participated. One maxillary first premolar subjected to orthodontic force was the test tooth. The contralateral first premolar, bracketed but not subjected to mechanical stress, was the control tooth. After a week of treatment, the first premolars were extracted and the dental pulp removed from the teeth. ALP activity was determined spectrophotometrically and the results expressed as units/liter per milligram of pulp tissue [U/(L x mg)]. RESULTS: ALP activity was 89 +/- 26 U/(L x mg) in the test teeth and 142 +/- 33 U/(L x mg) in the control teeth. The difference between the groups was statistically significant (P < .01). CONCLUSIONS: Orthodontic treatment can lead to significant early-phase reduction in ALP activity in human dental pulp tissue.

Adolescent↗