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PubMed2007

Effects of human relaxin on orthodontic tooth movement and periodontal ligaments in rats.

INTRODUCTION: The rate-limiting step in orthodontic treatment is often the rapidity with which teeth move. Using biological agents to modify the rate of tooth movement has been shown to be effective in animals. Relaxin is a hormone present in both males and females. Its main action is to increase the turnover of fibrous connective tissues. Thus, relaxin might increase the amount and rate of tooth movement through its effect on the periodontal ligament (PDL). The purpose of this study was to measure the effect of relaxin on orthodontic tooth movement and PDL structures. METHODS: Bilateral orthodontic appliances designed to tip maxillary molars mesially with a force of 40 cN were placed in 96 rats. At day 0, the animals were randomized to either relaxin or vehicle treatment. Twelve rats in each group were killed at 2, 4, 7, and 9 days after appliance activation. Cephalograms were taken at appliance placement and when the rats were killed. Tooth movement was measured cephalometrically in relation to palatal implants. Fractal analysis and visual analog scale assessments were used to evaluate the effect of relaxin on PDL fiber organization at the tension sites in histologic sections. The in-vitro testing for PDL mechanical strength and tooth mobility was performed by using tissue from an additional 20 rats that had previously received the same relaxin or vehicle treatments for 1 or 3 days (n = 5). RESULTS: Both groups had statistically significant tooth movement as functions of time. However, relaxin did not stimulate significantly greater or more rapid tooth movement. Fractal and visual analog scale analyses implied that relaxin reduced PDL fiber organization. In-vitro mechanical testing and tooth mobility assessments indicated that the PDL of the mandibular incisors in the relaxin-treated rats had reduced yield load, strain, and stiffness. Moreover, the range of tooth mobility of the maxillary first molars increased to 130% to 170%, over vehicle-treated rats at day 1. CONCLUSIONS: Human relaxin does not accelerate orthodontic tooth movement in rats; it can reduce the level of PDL organization, reduce PDL mechanical strength, and increase tooth mobility at early time points.

Animals↗
PubMed2006

Influence of orthodontic dental movement on the healing process of teeth with periapical lesions.

The purpose of this study was to histomorphologically evaluate (in dog's teeth) the influence of tooth movement in the healing of chronic periapical lesions. Thirty roots of incisors and premolars of two dogs (1-year-old) were used in this research. After pulpectomy, the root canals remained exposed to the oral environment for 6 months for achievement of periapical lesions. Twenty root canals were biomechanically prepared and received a calcium hydroxide dressing for 14 days before being filled with gutta-percha points and Sealapex sealer. After root canal treatment, some incisors were submitted to orthodontic movement, whereas the other roots remained without orthodontic movement. The orthodontic appliance was removed at 5 months and 15 days after treatment, the dogs were killed 15 days later and the specimens were prepared for histomorphological analysis. The results showed that the orthodontic movement delayed, but did not hinder, the periapical healing process.

Animals↗
PubMed1981

Augmentation genioplasty as an adjunct to conservative orthodontic treatment.

Augmentation genioplasty can serve as a valuable adjunct to orthodontic treatment. The borderline extraction patient with a good nasolabial angle, protruding lower incisors and a deficient chin often can be treated better by nonextraction orthodontics followed by advancement of the chin than by any regimen involving orthodontic extraction. Genioplasty also can be used to improve facial esthetics in the patient with a short mandibular ramus in whom mandibular advancement might well lead to unstable results. In some instances, genioplasty may be a way to overcome the appearance of facial asymmetry without requiring jaw surgery which would complicate a pre-existing adequate occlusion. As a relatively straightforward and predictable procedure, augmentation genioplasty should be used more often in conjunction with orthodontic treatment than it has been in the past.

Adolescent↗
PubMed1984

Clinical assessment of injuries in orthodontic movement of impacted teeth. II. Surgical recommendations.

Adverse effects on periodontal tissues have been associated with surgical techniques used to expose impacted teeth that are to undergo orthodontic tooth movement. The purpose of this study was to compare the effects on the periodontium of two of the more commonly used surgical techniques for labially impacted canines--(1) exposure of the entire labial aspect of the anatomic crown with total excision of all keratinized tissue (the window approach) and (2) a technique which exposes only 4 to 5 mm of the most superficial portion of the labial aspect of the cusp tip while maintaining 2 to 3 mm of keratinized tissue. Twelve patients were selected who had undergone comprehensive orthodontic therapy for a unilateral labial impaction of an upper canine, and who had the impacted canine surgically exposed with a window approach. This group's periodontal status after orthodontic therapy was compared to that of another group of twelve patients who had also undergone comprehensive orthodontic therapy for a unilaterally impacted labial upper canine but in whom the surgical exposure of the impacted tooth had been performed in a manner which preserved 2 to 3 mm of keratinized tissue on the labial aspect. The results indicated that the twelve subjects in whom the window approach had been used had statistically more gingival recession, gingival inflammation, and loss of attachment on the labial and labioproximal surfaces of the impacted teeth than the other group that had 2 to 3 mm keratinized tissue maintained after surgical exposure (p less than 0.05).

Adolescent↗
PubMedDate not supplied

Histomorphometric and biochemical study of osteoclasts at orthodontic compression sites in the rat during indomethacin inhibition.

Prostaglandins affect the number of osteoclasts at compression sites in orthodontic tooth movement. They may also have a role in tooth movement and influence the extent of root resorption. The purpose was to examine the effect of indomethacin on the activity of resident osteoclasts, recruitment of new osteoclasts and root resorption at orthodontic compression sites. Two separate populations of osteoclasts were studied: those resident at the sites after initial appliance activation and those recruited by a subsequent activation. Orthodontic appliances were activated to provide mesially directed forces of 40 g on the maxillary molars of rats. The appliances were activated with the same force after 4 days. The rats were killed at 1, 3, 6 and 10 days after initial activation. Half of the rats were injected with indomethacin. Tooth movement was measured cephalometrically; osteoclast numbers, sizes, numbers of nuclei per osteoclast and root resorption were assessed histomorphometrically; tartrate-resistant acid phosphatase (TRAP) in alveolar bone was measured biochemically. Indomethacin inhibited both initial tooth displacement and that following the delay. It also reduced the increase in osteoclast numbers, total osteoclast surface and alveolar bone TRAP at day 10. It had no effect on the surface area of each individual osteoclast or number of nuclei in each osteoclast. Root resorption increased in both groups but it was enhanced at day 10 in the indomethacin group. These data suggest that orthodontic tooth movement after appliance activation requires the recruitment of osteoclasts to sites of compression and that this is indomethacin-sensitive. Furthermore, indomethacin enhances root resorption at compression sites 10 days after appliance reactivation.

Acid Phosphatase↗
PubMed2003

Analysis of bone resorption after secondary alveolar cleft bone grafts before and after canine eruption in connection with orthodontic gap closure or prosthodontic treatment.

PURPOSE: We sought to analyze the success rate of secondary alveolar cleft bone grafts before and after canine eruption in connection with orthodontic gap closure or gap opening. PATIENTS AND METHODS: Sixty-eight secondary alveolar cleft bone grafts with iliac crest spongiosa were carried out in 57 patients (mean age, 9 years; age range, 8 to 11 years) with 11 bilateral and 46 unilateral clefts of the lip, alveolus, or palate. Gap closures were carried out after 53 bone grafts (78%), and gap openings with subsequent dental implants were carried out with 15 bone grafts (22%). The parameters acquired radiologically (orthopantomograms) at the time of the surgery and the follow-up examination (mean age, 3 years; age range, 7 months to 9 years) were 1) bone resorption in relation to the interdental height of the alveolar process in the vicinity of the cleft and 2) root growth of the teeth in the vicinity of the cleft. The statistically significant differences (P <.05) were monitored with a software program. Resorption grades I and II (>50% of the interalveolar bone height) were considered to be a success. RESULTS: Resorption was grade I in 69%, grade II in 19%, grade III in 10%, and grade IV in 1% of cases. Thus, the overall success rate was 88%. At the time of the osteoplasty, the root growth of the tooth in the immediate vicinity of the cleft was fully completed in 27 teeth (39%), three-quarters completed in 23 teeth (26.5%), and semicompleted in 18 teeth (33.8%). Twelve teeth (18%) in the vicinity of the cleft (lateral incisors/canine) remained unerupted and displaced after the surgery. It was necessary to expose unerupted teeth surgically to reposition them orthodontically. The resorption losses were significantly lower with gap closures than with gap openings (P <.001). However, bone grafts performed before canine eruption were largely carried out with the objective of orthodontic gap closure, in contrast to the bone grafts that were carried out after canine eruption (P <.02). CONCLUSION: Gap closures provide more favorable results than do gap openings in regard to resorption. Controlled dental eruptions or orthodontic gap closures reduce the graft resorption. The exact timing of surgery proved to be only a secondary consideration.

Alveolar Process↗
PubMed2000

Rapid orthodontic tooth movement into newly distracted bone after mandibular distraction osteogenesis in a canine model.

Orthodontic tooth movement through recently distracted fibrous bone tissue has not been investigated previously. We hypothesized that a tooth can be moved into the fibrous new bone created by the distraction process at a rapid rate. Four mature beagle dogs were used in this study. An edentulous space was created in 2 weeks by using a bone-borne intraoral distraction device on each side of the mandibular body between the third and fourth premolars. Calibrated elastic threads with 50 g of orthodontic force were applied to move the fourth premolar into the edentulous space for 5 weeks. On one side, the tooth was moved simultaneously with distraction; and on the opposite side, it was initiated immediately after the cessation of distraction. The fourth premolars were moved 1.2 mm per week. The results indicated that the best time to initiate tooth movement was immediately after the end of distraction. With this approach, most of the periodontal support was preserved after orthodontic tooth movement. In contrast, moderate to severe alveolar bone loss was noted in the fourth premolars moved simultaneously with distraction. This is one of the first experimental studies to demonstrate successful rapid orthodontic tooth movement into an edentulous space newly created by distraction osteogenesis. Clinical implications of these results may be applied to relieve severe dental crowding and to correct sagittal or transverse dental arch discrepancies.

Animals↗
PubMed1995

Pulp and periodontal healing, root development and root resorption subsequent to transplantation and orthodontic rotation: a long-term study of autotransplanted premolars.

One hundred and eighteen premolars transplanted at a stage with 3/4 to 4/4 root development with a wide open apical foramen were followed with standardized clinical and radiographic techniques for signs of pulpal and periodontal ligament healing and root development. Pulp healing, evaluated first by radiographic presence of pulp canal obliteration, appeared to be an earlier sign of pulp healing than the detection of pulp vitality with an electrometric test. Continued root growth of premolars was seen in some cases. Complete arrest of root development was usually followed by development of the missing root structure at the donor site, indicating a separation of the Hertwig's epithelial root sheath. Orthodontic rotation performed on 11 premolars induced slight surface resorption and a significant shortening of tooth length (mean 1.2 mm), compared with nontreated but transplanted control teeth. However, the extent of the apical root resorption is of minor clinical importance, and is equivalent to what has been found in previous investigations of orthodontic treatment of nontransplanted premolars. Late pulp necrosis occurred in 2 of the 11 treated cases 6 years after transplantation and 5 years after orthodontic rotation. To prevent late pulp necrosis, orthodontic rotation is recommended after periodontal healing and before total pulp canal obliteration has taken place, i.e., 3 to 9 months after transplantation.

Bicuspid↗
PubMed1996

Frequency of Bolton tooth-size discrepancies among orthodontic patients.

The purpose of this study was to determine the percentage of orthodontic patients who present with an interarch tooth-size discrepancy likely to affect treatment planning or results. The Bolton tooth-size discrepancies of 157 patients accepted for treatment in an orthodontic residency program were evaluated for the frequency and the magnitude of deviation from Bolton's mean. Discrepancies outside of 2 SD were considered as potentially significant with regard to treatment planning and treatment results. Although the mean of the sample was nearly identical to that of Bolton's, the range and standard deviation varied considerably with a large percentage of the orthodontic patients having discrepancies outside of Bolton's 2 SD. With such a high frequency of significant discrepancies it would seem prudent to routinely perform a tooth-size analysis and incorporate the findings into orthodontic treatment planning.

Dental Arch↗
PubMed1990

The case for postoperative orthodontics in orthognathic surgery.

In patients with orthognathic problems, in whom a combination of surgery and orthodontics is required, it seems to us better to defer orthodontic treatment until after surgery has been completed and a possible relapse tendency has petered out. This conclusion is reached on the basis of arch instability and the incidence of root resorption as reported in the orthodontic literature. The soundness of "permanent retention" after orthodontic therapy is questioned. The author's concepts are illustrated with a few case reports.

Humans↗
PubMed1997

Orthodontic-endodontic treatment planning of traumatized teeth.

Occasionally, an orthodontic patient will accidentally traumatize a maxillary anterior tooth before or during orthodontic treatment. In some situations, the trauma will be substantial and avulse the tooth. In other accidents, the tooth may not avulse, but the pulp becomes nonvital. If the pulp is devitalized, and the root has not fully formed, the apex of the root canal may be wide. In this situation, the endodontist may recommend apexification procedures to help close the apex before conventional obturation of the root canal. If the patient is currently undergoing orthodontic movement of the traumatized incisor, what effect will the tooth movement have on the success of the apexification? If the tooth were avulsed, replanted, and then ankylosed, should it be extracted? If so, when should the ankylosed incisor be removed? What effect will further facial growth have on the ankylosed tooth and the potential to achieve a successful esthetic restoration? The answers to these questions are important during the interdisciplinary treatment planning of the patient with traumatized teeth. This article will elucidate the endodontic-orthodontic considerations for patients with traumatized anterior teeth.

Adolescent↗
PubMed2001

Agreement between normative and perceived orthodontic need amongst deprived multiethnic school children in London.

The Index of Orthodontic Treatment Need (IOTN) has been used in dental epidemiology and to prioritize orthodontic treatment. The aim of this paper was to use the aesthetic component (AC) of the IOTN to measure agreement between normative and perceived orthodontic need amongst school children. Three hundred and seventy-eight children aged 11-14 years, enrolled in London UK state schools participated in this survey. The study focused on three ethnic groups: white, black and South Asian. Townsend deprivation scores suggested that the children were from areas of high socio-economic deprivation. Logistic regression analysis was carried out for agreement between normative and perceived need at each threshold value. Perceived need for braces, ethnic background, social class and hours of television viewing were significant variables. Black pupils were significantly less likely to concur on normative and perceived need scores, tending to perceive less need for treatment than did the dentist. Subjects from lower social classes were significantly more likely to concur on normative and perceived need scores. In conclusion, the study showed that using the IOTN AC at various points along the scale, different influences play a significant role in agreement/disagreement between normative and perceived needs, indicating that patient-clinician agreement regards orthodontic treatment is sensitive to several cultural factors.

Journal Article↗
PubMed2004

CD40-CD40L expression during orthodontic tooth movement in rats.

The aim of this study was to investigate the expression of the costimulatory molecules CD40 and CD40L in periodontal and bone cells in orthodontically treated and untreated teeth using immunohistochemistry. The upper first molars were moved mesially by a fixed appliance. In the experimental group, CD40+ cells were detected at both the tension and the resorption sides in fibroblast-, macrophage-, and dendritic-like cells. The staining was more pronounced on the resorption side. The strongest expression was observed on day 3, decreased on day 7, and reached a low level on day 10 after application of orthodontic force. In contrast, in the treated animals CD40 ligand was expressed on day 3, the expression was enhanced on day 7, and was more pronounced on day 10. CD40L-expressing cells were found predominantly around hyalinized tissue in the resorption zone and the tension areas of the distal root. CD40L was expressed in the bone marrow cells in the pressure zone. In the tension side, some cells of the cellular cementum expressed CD40L. The expression of CD40 and CD40L was low in untreated teeth. These results suggest that CD40-CD40L interaction appears to be an active process during orthodontic tooth movement and that orthodontic force induces T-cell activation. Such activation may be involved in the induction of inflammatory mediators and subsequent bone remodeling. In addition, this may lead to the generation of anti-inflammatory mediators that support defense mechanisms against root resorption, which depend on the type of immune response that is induced regarding CD40-CD40L expression.

Animals↗
PubMed2000

The relationship of 2 professional occlusal indexes with patients' perceptions of aesthetics, function, speech, and orthodontic treatment need.

The aim of this study was to determine the relationship between patients' perceptions of orthodontic treatment need and need as determined with professionally derived indexes, namely the dental aesthetic index and the index of orthodontic treatment need. This study was undertaken at orthodontic offices in San Francisco, Calif. The pretreatment study casts of 50 consecutive patients, presenting for orthodontic treatment, were objectively assessed with these indexes by 2 examiners trained and calibrated in their use. Patients were asked to complete a questionnaire consisting of 4 questions addressing appearance, function, speech, and treatment need, using either a 5-point Likert scale or a yes/no response. The professionally derived indexes showed that statistically significant correlations existed between the aesthetic component and dental health component (r = 0.46; P <.01), the aesthetic component and dental aesthetic index (r = 0.54; P <.01), and the dental health component and dental aesthetic index (r = 0.46; P <.01). Statistically significant correlations were also found for subjective assessments between biting/chewing and speech (r = 0.31; P <.05), between speech and the aesthetic component (r = -0.39; P <. 01) and the dental aesthetic index (r = 0.34; P <.05), and between the aesthetic component and appearance (r = -0.28; P <.05). Logistic regression analysis after dichotomization (treatment/no treatment need) confirmed that the aesthetic component was the only statistically significant factor (odds ratio, 0.57; 95% confidence limits 0.34 to 0.97).

Adolescent↗
PubMed2001

Osteoclast clearance from periodontal tissues during orthodontic tooth movement.

The presence of osteoclasts at locations of alveolar bone remodeling is antecedent to orthodontic tooth movement. Cell recruitment and clearance are the mechanisms by which osteoclast populations are regulated. Research in other tissues has revealed that many cells die after their functional lives are past by a process called apoptosis, or programmed cell death. The purpose of this study was to examine the role of apoptosis in osteoclast clearance at orthodontically treated sites as a function of time and location. Orthodontic appliances were placed on 96 rats of the Sprague-Dawley strain. The rats were assigned to either treatment or sham (control) groups and killed 1, 3, 5, and 7 days after appliance placement. Tissue samples were prepared for histochemical evaluation and quantification of morphologic features. Tartrate-resistant acid phosphatase (TRAP) and ApopTag (TdT-mediated dUTP-biotin nick 3' end labeling) stains were used to identify osteoclasts and committed preosteoclasts and to discriminate between apoptotic and nonapoptotic nuclei. Pyknotic nuclei and apoptotic bodies were also counted as a morphologic assessment of apoptosis. The percentages of TRAP/ApopTag-positive nuclei were measured in 4 different periodontal regions. There was a highly significant difference in the overall percentage of TRAP/ApopTag-positive nuclei between the control and the treatment groups at 3, 5, and 7 days (P <.001). Morphologic criteria were also statistically different at days 5 and 7 (P <.05). These data strongly suggested that osteoclasts recruited for orthodontic tooth movement are, at least in part, cleared by apoptosis.

Acid Phosphatase↗
PubMed1994

The need for orthodontic treatment in the child population of the United Kingdom.

The effective management of a public dental health system requires accurate data on the needs of the population. Previous assessments of the levels of orthodontic treatment need in populations, by both epidemiologists and orthodontists, vary considerably. This paper presents the findings of two independent investigations into orthodontic treatment need in the United Kingdom using the Index of Orthodontic Treatment Need (IOTN, Brook and Shaw, 1989). The results indicate that approximately one-third of 11-12-year-olds were in objective need of orthodontic treatment. The basis for allocation to the treatment need groups was similar in both studies, as were the proportions of the most severe occlusal traits.

Chi-Square Distribution↗
PubMed2001

Prevalence of malocclusion and orthodontic treatment need in children and adolescents in Bogota, Colombia. An epidemiological study related to different stages of dental development.

The aim of the study was to assess the prevalence of malocclusion in a population of Bogotanian children and adolescents in terms of different degrees of severity in relation to sex and specific stages of dental development, in order to evaluate the need for orthodontic treatment in this part of Colombia. A sample of 4724 children (5-17 years of age) was randomly selected from a population that attended the Dental Health Service; none had been orthodontically treated. Based on their dental stages the subjects were grouped into deciduous, early mixed, late mixed and permanent dentition. The registrations were performed according to a method by Björk et al. (1964). The need for orthodontic treatment was evaluated according to an index used by the Swedish National Board of Health. The results showed that 88 per cent of the subjects had some type of anomaly, from mild to severe, half of them recorded as occlusal anomalies, one-third as space discrepancies, and one-fifth as dental anomalies. No clear sex differences were noted, except for maxillary overjet, spacing, tooth size (all more frequent in boys), and crowding (more frequent in girls). Occlusal anomalies and space discrepancies varied in the different dental developmental periods, as did tipped and rotated teeth. Little need for orthodontic treatment was found in 35 per cent and moderate need in 30 per cent. A great need was estimated in 20 per cent, comprising children with prenormal occlusion, maxillary overjet, or overbite (> 6 mm), posterior unilateral crossbite with midline deviation (> 2 mm), severe crowding or spacing, congenitally missing maxillary incisors, impacted maxillary canines or anterior open bite (> 3 mm in the permanent dentition). Urgent need for treatment was estimated to be 3 per cent, comprising subjects with extreme post- and pre-normal occlusion, impacted maxillary incisors or extensive aplasia.

Adolescent↗
PubMed2003

The level of cathepsin B in gingival crevicular fluid during human orthodontic tooth movement.

This investigation examined gingival crevicular fluid (GCF) levels of lysosomal cystein protease, cathepsin B (CAB), during human orthodontic tooth movement. The study included 10 patients (five males, mean age 22.5 +/- 2.8 years and five females, mean age 23.4 +/- 3.9 years), each having one tooth undergoing orthodontic movement, while the contralateral and antagonist teeth were used as the controls. The GCF was sampled at the control and treatment (compression) sites before activation and at 1, 24, and 168 hours. Prevention of plaque-induced inflammation allowed this study to focus on the dynamics of mechanically stimulated CAB levels in GCF. The CAB levels in GCF were determined by fluorospectrometry, using Z-Arg-Arg-MCA as the substrate and by Western blotting analysis. The GCF levels of CAB for the treated teeth were significantly (P< 0.001) higher than those of the control teeth at 24 hours. At the control sites, CAB levels at 24 hours did not change significantly with time. At the experimental site where orthodontic forces were applied, Western blot analysis demonstrated that the molecular forms were 29 kDa mature enzymes. These results indicate that the amount of CAB in GCF is increased by orthodontic tooth movement. This increased CAB may be involved in extracellular matrix degradation in response to mechanical stress.

Adult↗