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PubMed1996

The influence of extraction versus non-extraction orthodontic treatment on the soft tissue profile.

The aim of the present study was to study profile changes following orthodontic harmonization of enlarged overjet and to attempt to trace predictive aspects regarding prognosis of the soft tissue changes. Lateral cephalograms and study models of 40 female patients, at least 12 years old at the start of treatment, with an overjet of > or = 6 mm were analyzed before (T1) and after treatment (T2). Twenty patients were treated without extractions, while in the remaining 20 patients extractions of premolars were carried out bilaterally in both jaws. The 2 groups were found to be highly homogeneous as regards overjet, cephalometric characteristics, space condition in the upper arch at T1 and both at T1 and T2 as regards age. The most striking aspect of the findings was the considerable amount of variability of the soft tissue changes. These changes were found to be rather unpredictable for the individual patient, since the regression models employed could give only a very wide individual prediction range. The relatively small changes registered, using superimposition methods, in both groups as regards the sagittal position of the lips in comparison to the very strong changes observed in relation to the esthetic line shows that the influence of the growth of the chin and/or the nose on the facial profile might be more important than the influence of the orthodontic treatment. The interpretation of the findings in the present study suggests that, apart from marked cases of skeletal convexity or concavity, the extraction versus non-extraction decision should be based primarily upon current knowledge of long-term stability of orthodontic treatment results.

Adolescent↗
PubMed1997

Orthodontic treatment and temporomandibular disorder: is there a relationship? Part 2: Clinical implications.

Although a review of the current literature does not reveal compelling evidence for the claim that orthodontic treatment prevents, causes, or cures temporomandibular disorders (TMD), the currently available clinical studies devoted to this topic share some methodological weaknesses, some of which are discussed in the present article. Another purpose of this paper is to extend the current understanding about the relationship between orthodontics and TMD to situations occurring in routine clinical practice. By doing so, we provide suggestions that are intended to help the orthodontist in decision-making when he or she deals with a patient who is in need of orthodontic treatment for dental or skeletal reasons, but has a history of TMD, or who develops TMD signs and symptoms during or after treatment.

Adolescent↗
PubMed2002

Results of transplanting developing third molars as part of orthodontic space management. Part 1: clinical and radiographic results.

PATIENTS AND METHOD: The aim of the present study was to contribute to a more accurate indication and better integration of developing third molar transplantation into orthodontic space management, using the results gleaned from the authors' own pool of patients. For this purpose, a clinical and radiographic examination of 61 transplanted developing molars in 57 patients was carried out after an average of 3.3 years. RESULTS: The overall success rate was 85%. Failure was due in 10% of cases to impaired periodontal healing (inflammatory root resorption, ankylosis, or increased pocket probing depths) and in 5% of cases to insufficient or arrested postoperative root development accompanied by increased transplant mobility. The incidence of postoperative cessation of further root development was significantly higher (p = 0.011) in transplants at early developmental stages, which also had a negative impact on the final root length, the crown-root ratio and the mobility values of these transplants. CONCLUSIONS: The transplantation of developing third molars should be given stronger consideration in treatment plans for orthodontic space management although it represents a real alternative to orthodontic space closure only in exceptional cases. However, unlike implantological or prosthodontic treatment, it offers an opportunity to replace a missing or non-retainable tooth with a patient's own vital and fully functional tooth, provided the appropriate transplant is selected.

Adolescent↗
PubMed2002

Bilateral open bite in dicygotic twins. A combined orthodontic-prosthetic approach.

CASE REPORT: Dizygotic twins, male, 25 years of age, required treatment for an identical orthodontic diagnosis. DIAGNOSIS: Class III malocclusion with mesial molar relation and frontal edge-to-edge bite, lyrate upper dental arch, grouped cross-bite and bilateral open bite in the molar and bicuspid region, retention and lingual inclination respectively of the lower left second bicuspid, mesial inclination of both lower first molars. The severity of the malocclusion differed in the two brothers. THERAPY: Orthodontic treatment was successful concerning the transversal expansion and alignment of the maxillary dental arch, the functional relation of the anterior teeth, the transversally correct relation of the upper and lower dental arches and, following surgical removal of the lower second bicuspids, the reduction of crowding in the lower arch. An attempt was made to upright the molars in the mandibular arch and to close the lateral open bite by means of vertical elastics. However, the 10-month period of resistance to the therapy suggested, after a tongue protrusion habit had been ruled out, a diagnosis of ankylosis. Further orthodontic treatment was renounced and a prosthetic solution was pursued instead: the teeth in infraocclusion were treated with full ceramic overlays and, in the regions with residual gaps, with pontics (Empress II, Ivoclar, Schaan, Liechtenstein), after minimally invasive preparation (confined to removal of existing fillings). CONCLUSION: This case is particularly interesting because the infrapositioned molars in both brothers were very likely due to ankylosis, suggesting a genetic cause.

Adult↗
PubMed2003

Apical root resorption after lingual orthodontic therapy.

PURPOSE: Apical root resorptions are among the undesirable side effects of orthodontic therapy. The aim of the present study was to investigate radiologically whether and to what extent resorptions occur in patients treated solely with a fixed lingual appliance, as well as the pathogenetic relevance of the extent and direction of the therapeutically induced apical movement. PATIENTS AND METHODS: The collective comprised 33 female and seven male patients with a mean age of 24.2 +/- 8.4 years. Permanent lower premolars were extracted in five, and permanent upper premolars in 22 patients. In total, 456 upper and lower incisors and canines were assessed. In order to evaluate the relative change in root length and the sagittal and vertical apical movements, pre- and posttherapeutic panoramic radiographs and/or lateral cephalograms were analyzed. RESULTS: After completion of orthodontic treatment the mean root length was 96.3%, corresponding to a resorption rate of 3.7%. The resorption rates of teeth 11, 12 and 21 differed significantly from those of teeth 31, 32 and 43. Upper incisors presented increased mean resorption rates < or = 10%. Only 18% of the 456 teeth analyzed were affected by pronounced resorptions > 10%. 82% of the teeth were resorption-free. A patient-related evaluation revealed that 26 of the 40 patients had no resorptions > 20%, while 14 had between one and four affected teeth. No significant relationship between extent of resorption and parameters such as age, gender, active treatment time, Angle class, or extent and direction of apical movement was recorded. CONCLUSIONS: The results suggest that lingual orthodontic therapy resulted in only slight root resorptions. Pronounced root shortenings were observed in some patients whose individual predisposition may constitute the main risk factor for the occurrence of root resorptions.

Adolescent↗
PubMed2005

Light microscopic and SEM findings after orthodontic treatment--analysis of a human specimen.

AIM: The hard and soft tissue damage caused by orthodontic forces has so far, for obvious ethical reasons, been investigated in animal models primarily. However, the validity of these results as applied to humans remains controversial. The particular value of this study is that the maxilla of a young adult could be analyzed histologically. Thus it was possible to retrospectively study the effects of a routine orthodontic therapy using light microscopy. MATERIAL AND METHODS: The upper jaw of a 24-year-old patient was investigated. He had been in orthodontic treatment with a straight-wire-appliance using superelastic materials for 18 months. Both posterior segments were analyzed in the horizontal plane using the microsection method according to Donath (toluidine blue staining). Both central incisors were analyzed using a scanning electron microscope (SEM). The examination was performed qualitatively and histomorphometrically. RESULTS: 170 lateral root resorptions were found in the nine posterior teeth, while pressure sites and interference areas with the buccal and sinus cortical bone were predominantly affected. However, the extent of root resorption was minimal: mean length 979 +/- 766 microm, mean depth 208 +/- 133 microm. The lateral root erosions presented high repair potential: 55.6% of resorption length, and 28% of the depth were repaired in 76% of all lesions. CONCLUSION: The incidence of detected root resorptions seems high at first. However, the prognosis of the affected teeth is not critically impaired, due to the lesions' minor extent (length, depth) and their high repair capacity.

Adult↗
PubMed2005

Magnetic field interactions of orthodontic wires during magnetic resonance imaging (MRI) at 1.5 Tesla.

BACKGROUND: Orthodontic appliances pose a potential risk during magnetic resonance imaging (MRI) due to forces on metallic objects within the static magnetic field of MRI systems. The aim of the present investigation was to measure forces on orthodontic wires caused by the static magnetic field of a 1.5-Tesla MRI system, and to assess the safety hazards associated with these forces. MATERIALS AND METHODS: Thirty-two different orthodontic wires (21 arch wires, eight ligature wires and three retainer wires) were investigated in a 1.5-Tesla MRI system (Magnetom Symphony, Siemens Medical Solutions, Erlangen, Germany). The translational forces were measured using the deflection angle test (ASTM F2052-02); rotational forces were assessed on a 5-point qualitative scale. RESULTS AND CONCLUSION: All retainer wires and the steel arch wires (the Noninium arch wire being the exception) were subjected to considerable rotational and translational forces within the MRI system's magnetic field. Translational forces were from 9.1- to 27.6-times as high as gravitational forces on these objects. Steel ligature wires and arch wires made of cobalt chromium, titanium molybdenum, nickel-titanium, and brass alloys showed no or negligible forces within the magnetic field. The translational and rotational forces within the MRI magnetic field should pose no risk to carefully-ligated arch wires. Steel retainer wire bonds should be checked to ensure secure attachment prior to an MRI investigation.

Biocompatible Materials↗
PubMed2006

Orthodontic procedures in the treatment of obstructive sleep apnea in children.

INTRODUCTION: Even minor dimensional changes in the child's upper airway can already affect the resistance therein. Craniofacial anomalies may constrict the upper airway and are suspected to be a direct cause of obstructive sleep apnea syndrome (OSAS) in children. CASE REPORTS: In the present two cases we report on the successful orthodontic treatment of an 8-year-old girl and a 6 1/2-year-old boy with craniofacial anomalies and severe OSAS diagnosed during a sleep study. The primary treatment aim was to improve the cardio-respiratory situation during sleep by enlarging the upper airway and preventing its collapse. Prior to the onset of treatment we had ruled out the presence in both children of any adenotonsillar hypertrophy requiring surgical treatment. Patient 1 (the girl) presented mouth breathing predominantly while sleeping and a narrow skeletal maxilla that was treated via rapid maxillary expansion followed by a Fränkel-II appliance. A function regulator type-II was applied in the second patient, a boy suffering from OSAS, and spinal muscular dystrophy with a narrow skeletal upper jaw and mandibular retrognathism. We were able to successfully treat both cases of obstructive sleep apnea with these orthodontic procedures. CONCLUSION: Orthodontic therapeutic measures should be considered as a causal treatment option in children with OSAS and craniofacial anomalies restricting the upper airway. Parents and patient cooperation, as well as good interdisciplinary care within the field of sleep medicine are mandatory for this kind of treatment.

Anodontia↗
PubMed2006

Mini- and micro-screws for temporary skeletal anchorage in orthodontic therapy.

OBJECTIVE: Mini- and micro-screws are of increasing interest in orthodontic therapy in cases where maximum anchorage is requested. In this study we aimed to identify the criteria that influence the clinical success of micro-implants. MATERIAL AND METHODS: 239 micro-implants were inserted for skeletal anchorage in 85 patients undergoing orthodontic therapy. The survival rates of the first 133 implants were analyzed and those results were later applied in treating subsequent patients. RESULTS: In so doing, we were able to reduce the loss rate from 23% to 5%. Using thicker implants on the labial side of the lower jaw and the lingual side of the upper jaw was an important factor in reducing failure rates. We found the lower jaw's lingual side to be an inadequate region for inserting micro-implants. Thinner micro-implants were selected for the upper jaw's labial side. CONCLUSION: By following these guidelines, practitioners may find mini- and micro-screws to offer reliable orthodontic support.

Adolescent↗
PubMed2006

Parameters affecting primary stability of orthodontic mini-implants.

AIM: Treatment options in orthodontics have been expanded by skeletal anchorage via mini-implants over the last few years. Sufficient primary stability is imperative to minimize implant loss rate. The aim of this study was to quantitatively analyze the factors influencing primary stability: bone quality, implant-design, diameter, and depth of pilot drilling. MATERIAL AND METHODS: Thirty-six pelvic bone segments (ilium) of country pigs were dissected and embedded in resin. To determine the primary stability, we measured the insertion torque of five different mini-implant types (tomas-pin [Dentaurum, Ispringen, Germany] 08 and 10 mm, and Dual Top [Jeil Medical Corporation, Seoul, Korea] 1.6 x 8 and 10 mm plus 2 x 10 mm). Twenty-five or 30 implants were inserted into each pelvic bone segment following preparation of the implant sites using pilot drill diameters of 1.0, 1.1, 1.2 and 1.3 mm and pilot drill depths of 1, 2, 3, 6 and 10 mm. Five implants were inserted for reference purposes to establish comparability. Thicknesses of bone compacta were measured via micro-computer tomography. RESULTS: Insertion torques of orthodontic mini-implants and therefore primary stability varied greatly, depending on bone quality, implant-design, and preparation of implant site. Compared with the tomas-pin, the Dual Top screw showed significantly greater primary stability. Torque moments beyond 230 Nmm caused fractures of 9 Dual Top screws. CONCLUSION: Compacta thickness, implant design and implant site preparation have a strong impact on the primary stability of mini-implants for orthodontic anchorage. Depending on the insertion site and local bone quality, the clinician should choose an optimum combination of implant and pilot-drilling diameter and depth.

Animals↗
PubMed1976

Preventing enamel decalcification during orthodontic treatment.

One hundred thirty-two extracted premolar teeth were selected and divided into four equal groups. The first group of thirty-three teeth received a topical application of acidulated phosphate fluoride; the second group, a topical application of stannous fluoride; the third group, an application of a polymeric adhesive coating; the fourth group was left untreated to serve as a control. On each tooth a loosely fitted orthodontic band was cemented to place. After cementation, the band was broken to simulate a loose orthodontic band in vivo. The four groups of teeth were simultaneously immersed in a decalcifying gelatin and were left undisturbed for 11 weeks. The teeth were then removed and a record was made of the decalcification produced. A chi-square test was used to compare the teeth in each group to those in every other group. Compared to a control group of teeth, those teeth treated with polymeric adhesive coating, acidulated phosphate fluoride, or stannous fluoride produced a statistically significant reduction in decalcification of the tooth surfaces beneath loose orthodontic bands. For a one-application technique, the polymeric adhesive coating provided more protection against decalcification of teeth under loose orthondontic bands than did either acidulated phosphate fluoride or stannous flouride.

Calcium Metabolism Disorders↗
PubMed1978

Bone reaction to orthodontic forces on vitreous carbon dental implants.

On the basis of a very small sample in dogs, it appears that orthodontic techniques cannot be used to move a vitreous carbon implant. Therefore, one should not use implants before the completion of orthodontic treatment in persons who may require orthodontic service unless the implants are to be used for anchorage. Alveolar bone heals in very close apposition to vitreous carbon implants in dogs. Prior experiments with vitreous carbon implants have been conducted with free-standing implants; in this study a substantial number of implants became excessively mobile and exfoliated. Therefore, it is recommended that implants be stabilized through the bone-healing period. Because of the small sample, this study should be considered as only a pilot study and observations made should be considered solely as guidelines.

Animals↗
PubMed1983

Primate models in surgical orthodontics.

Between 1969 and 1980, 22 studies using nonhuman primates for experimental research in surgical orthodontics were published in the American Journal of Orthodontics, Angle Orthodontist, Journal of Oral Surgery, or International Journal of Oral Surgery. The most common species used was the rhesus monkey, Macaca mulatta. As laboratory animals, monkeys are relatively expensive and difficult to obtain. These problems have limited the design of experimental studies. Sample sizes are often too small for statistical analysis, control groups are small or omitted, and it has frequently been necessary to pool animals of different ages and sexes. These compromises might be appropriate if monkeys are the best available experimental model for humans, but there is little evidence that this is the case. Monkeys do not fill the usual role of good experimental models, which is to simplify a complex system. The monkeys used for craniofacial surgery have normal craniofacial function and morphology for their species, unlike human clinical patients. Cephalometric radiographs and skull measurements taken on monkeys of the five most common experimental species indicate that all experimental animals are much more prognathic than humans, and sex differences in prognathism are small. However, because many species have a large sex difference in canine size, females are a better experimental model than males for some questions. Considering recent federal legislative interest in animal research and the decreasing financial support for research, it is essential that the choice of experimental animals be justifiable and cost-effective. It would be worthwhile to consider alternatives to primates as the species of choice for experimental research in surgical orthodontics.

Animals↗
PubMed1983

The surgical-orthodontic correction of mandibular deficiency. Part II.

As discussed in Part I of this study, persons with mandibular deficiency and Class II malocclusions exhibit a wide spectrum of esthetic, cephalometric, and occlusal characteristics. In many such patients optimal overall results are best obtained via a combined orthodontic-surgical approach. In such patients a critical evaluation is essential to decide (1) the optimal operation and (2) the appropriate orthodontic-surgical sequencing. Our method of making these two basic decisions was presented in Part I. In this article the indications for mandibular advancement with or without genioplasty, total subapical mandibular advancement, superior repositioning of the maxilla, and inferior repositioning of the maxilla are discussed in detail. These alternatives are illustrated with representative cases, and the results are discussed. The intention of these two presentations is to illustrate an orthodontic-surgical approach to the correction of mandibular deficiency and Class II malocclusion that is predicated on a systematic evaluation of the individual patient rather than a standard approach.

Adolescent↗
PubMed1983

Maximum forces and deflections from orthodontic appliances.

The maximum bending moment of an orthodontic wire is an important parameter in the design and use of an orthodontic appliance. It is the wire property that determines how much force an appliance can deliver. A bending test which allows direct measurement of the maximum bending moment was developed. Data produced from this test are independent of wire length and configuration. The maximum bending moment, percent recovery, and maximum springback were determined for round and rectangular cross sections of stainless steel, nickel-titanium, and beta-titanium wires. The data suggest the need for more specifically defining maximum moment and maximum springback. Three maximum bending moments are described: Me, My, and Mult. My and Mult are clinically the most significant. Appliances that are required to have no permanent deformation must operate below My. Appliances that exhibit marked permanent deformation may be used in some applications and, if so, higher bending moments can be produced. In order of magnitude, the maximum bending moment at yield is largest in stainless steel, beta-titanium, and nickel-titanium for a given cross section. Nickel-titanium and beta-titanium have significantly larger springback than stainless steel determined at the moment at yield. Nickel-titanium did not follow the theoretical ratio between ultimate bending moment and the bending moment at yield, exhibiting a very large ratio. The study supports the hypothesis that most orthodontic appliances are activated in a range where both plastic and elastic behavior occurs; therefore, the use of yield strengths for calculation of force magnitude can lead to a significant error in predicting the forces delivered.

Dental Alloys↗
PubMed1986

Root resorption in maxillary central incisors following active orthodontic treatment.

The purpose of this study was to determine if apical root resorption associated with orthodontic treatment continues after the termination of active treatment (that is, the removal of fixed appliances). A sample of 45 subjects who had experienced root resorption during treatment was selected from the orthodontic clinic at the State University of New York at Buffalo. The length of the maxillary central incisors was measured from lateral cephalometric radiograms taken before treatment, after active treatment, and after retention. From these data, the resorption occurring during and after active treatment was calculated. The mean amount of root resorption during active treatment was 2.93 mm. The mean amount of root resorption during the posttreatment period was 0.1 mm. There was a statistical difference between these two means using the Student's t test at the 0.05 level of significance. The reliability coefficient comparing the first tracings and measurements in the 19 cases that were retraced and remeasured was r = 0.993. The data from this radiographic study support the hypothesis that root resorption associated with orthodontic treatment ceases with the termination of active treatment. There was also evidence to suggest that when posttreatment root resorption does occur, it is not necessarily associated with large amounts of root resorption during the active treatment period. It is more likely associated with other factors, such as traumatic occlusion and active force-delivering retainers.

Adolescent↗
PubMed1990

Substance P immunoreactivity in periodontal tissues during orthodontic tooth movement.

Neurotransmitters, such as substance P (SP), may mediate the biological response to mechanical stress applied to teeth during orthodontic treatment. This hypothesis was investigated immunohistochemically on maxillae of cats which had one maxillary canine tipped distally for a period of time ranging from 1 h to 14 days. Horizontal histological sections 5 microns thick, collected on adhesive tape while still frozen, then freeze-dried, were stained by an immunoglobulin-enzyme bridge method using rabbit anti-SP polyclonal antibodies. The specificity of the staining was evaluated either by using the serum of non-immunized rabbits in lieu of anti-SP serum, or by pre-incubating the anti-SP serum with the antigen. Only sparse SP-like immunoreactivity was detected in the dental pulp, near or in the walls of blood vessels, or in the periodontal ligament (PDL) of unstressed canines. However, the density of neuronal elements exhibiting positive staining for SP appeared to increase markedly after application of an orthodontic force. This phenomenon occurred rapidly (3 h) in the dental pulp, but later in the PDL (24 h to 14 days), mainly at compression sites. These results demonstrate that the stimulation of periodontal nerve terminals by means of orthodontic forces may induce the peripheral release of the neurotransmitter SP, suggesting that it may be an initial trigger for a biochemical cascade which comprises the activation of various types of PDL cells.

Animals↗
PubMed1993

Shear bond strength of orthodontic brackets using Panavia: an in-vitro study.

In this study, Panavia (a phosphonated Bis-GMA resin which is known to develop very high bond strengths with resin-bonded bridges) is compared to a conventional no-mix orthodontic Bis-GMA bracket adhesive. Results showed that there was no statistically significant difference in the shear bond strengths between the two resins when used as adhesives for bonding orthodontic brackets. Coupled with the fact that Panavia requires an anaerobic environment for complete polymerization, its routine use as a bracket adhesive in direct bonding of orthodontic brackets is not indicated.

Dental Bonding↗