Which orthodontic archwire sequence? A randomized clinical trial.

Eur J Orthod. 2006 Dec;28(6):561-6

Authors: Mandall N, Lowe C, Worthington H, Sandler J, Derwent S, Abdi-Oskouei M, Ward S

The aim of this study was to compare three orthodontic archwire sequences. One hundred and fifty-four 10- to 17-year-old patients were treated in three centres and randomly allocated to one of three groups: A = 0.016-inch nickel titanium (NiTi), 0.018 x 0.025-inch NiTi, and 0.019 x 0.025-inch stainless steel (SS); B = 0.016-inch NiTi, 0.016-inch SS, 0.020-inch SS, and 0.019 x 0.025-inch SS; and C = 0.016 x 0.022-inch copper (Cu) NiTi, 0.019 x 0.025-inch CuNiTi, and 0.019 x 0.025-inch SS. At each archwire change and for each arch, the patients completed discomfort scores on a seven-point Likert scale at 4 hours, 24 hours, 3 days, and 1 week. Time in days and the number of visits taken to reach a 0.019 x 0.025-inch SS working archwires were calculated. A periapical radiograph of the upper left central incisor was taken at the start of the treatment and after placement of the 0.019 x 0.025-inch SS wire so root resorption could be assessed. There were no statistically significant differences between archwire sequences A, B, or C for patient discomfort (P > 0.05) or root resorption (P = 0.58). The number of visits required to reach the working archwire was greater for sequence B than for A (P = 0.012) but this could not be explained by the increased number of archwires used in sequence B.

PMID: 17041083 [PubMed - indexed for MEDLINE]

In vitro toxicity evaluation of silver soldering, electrical resistance, and laser welding of orthodontic wires.

Eur J Orthod. 2006 Dec;28(6):567-72

Authors: Sestini S, Notarantonio L, Cerboni B, Alessandrini C, Fimiani M, Nannelli P, Pelagalli A, Giorgetti R

The long-term effects of orthodontic appliances in the oral environment and the subsequent leaching of metals are relatively unknown. A method for determining the effects of various types of soldering and welding, both of which in turn could lead to leaching of metal ions, on the growth of osteoblasts, fibroblasts, and oral keratinocytes in vitro, is proposed. The effects of cell behaviour of metal wires on osteoblast differentiation, expressed by alkaline phosphatase (ALP) activity; on fibroblast proliferation, assayed by the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulphophenil)-2H-tetrazolium-phenazine ethosulphate method; and on keratinocyte viability and migration on the wires, observed by scanning electron microscopy (SEM), were tested. Two types of commercially available wires normally used for orthodontic appliances, with a similar chemical composition (iron, carbon, silicon, chromium, molybdenum, phosphorus, sulphur, vanadium, and nitrogen) but differing in nickel and manganese content, were examined, as well as the joints obtained by electrical resistance welding, traditional soldering, and laser welding. Nickel and chromium, known as possible toxic metals, were also examined using pure nickel- and chromium-plated titanium wires. Segments of each wire, cut into different lengths, were added to each well in which the cells were grown to confluence. The high nickel and chromium content of orthodontic wires damaged both osteoblasts and fibroblasts, but did not affect keratinocytes. Chromium strongly affected fibroblast growth. The joint produced by electrical resistance welding was well tolerated by both osteoblasts and fibroblasts, whereas traditional soldering caused a significant (P < 0.05) decrease in both osteoblast ALP activity and fibroblast viability, and prevented the growth of keratinocytes in vitro. Laser welding was the only joining process well tolerated by all tested cells.

PMID: 17035485 [PubMed - indexed for MEDLINE]

Improvement of pseudoelasticity and ductility of Beta III titanium alloy--application to orthodontic wires.

Eur J Orthod. 2007 Feb;29(1):8-13

Authors: Laheurte P, Eberhardt A, Philippe M, Deblock L

The pseudoelasticity of metastable Beta III titanium alloy (TMAtrade mark) used for orthodontic applications is obtained by cold wiredrawing. This wire has higher rigidity than cold-drawn NiTi (Nitinoltrade mark, superelastic NiTi SE) and lower recoverable deformation. The low ductility value of Beta III is due to the deformation imposed by wiredrawing. The aim of this research was to improve the behaviour of this alloy by modifying the microstructural parameters to decrease the rigidity and increase the recoverable deformation and ductility of the alloy. The effects of second phase precipitate, grain size, and deformation on the wire mechanical properties were also examined. The isothermal precipitation of alpha (alpha) or omega (omega(isoth)) phases precludes the expression of the pseudoelastic effect. The presence of an omega(isoth) phase considerably increases fracture strength, whereas the alpha phase strongly decreases the ductility and adversely affects the strain recovery (epsilon(r)). To control the grain size, the growth of the recrystallized grains was studied by considering several parameters, which are known to have an influence on grain size, including the cold rolled strain, the temperature, the time of annealing, and the initial grain size. A structure with coarse grains, quenched from a temperature higher than the beta transus (T(beta)), associated with a plastic pre-deformation, contributed to an improved pseudoelastic behaviour, due to the presence of a reversible martensite phase (alpha'') induced by the pre-deformation.

PMID: 16954181 [PubMed - indexed for MEDLINE]

Toxicity of used orthodontic archwires assessed by three-dimensional cell culture.

Eur J Orthod. 2006 Oct;28(5):426-32

Authors: Vande Vannet B, Mohebbian N, Wehrbein H

The aim of the present study was to determine whether used orthodontic wires made of different materials cause toxicity and loss of viability on three-dimensional (3D) cell cultures. Three types of orthodontic wires, stainless steel, Nitinol, and TMA (n = 9) which had been used clinically in fixed appliances for a period of 1 month, were retrieved at random from five patients. Both upper and lower archwires were collected and subjected to two different protocols: to assess toxicity, two pieces of each wire were placed on 3D cell cultures (reconstituted human epithelium); to investigate the possibility of cell damage, the 3-(4,5-dimethylthiazol-2-yl)2,5-diphenyl tetrazolium bromide (MTT) assay was used and haematoxylin and eosin staining was performed to evaluate morphological changes. Copper wire served as the control to determine the morphology of severe toxicity, and native cell cultures and silk were used as the negative controls. Morphological evaluation of the native cell cultures revealed no toxic reactions. The ranking, from mild to severe toxicity was as follows: stainless steel < Nitinol = TMA. There were no significant differences between TMA and Nitinol. The MTT assay revealed the following mean percentage values for viability: native cell line (negative control), 100; stainless steel, 102.25; TMA, 87.4; Nitinol, 85.3; and copper wire (positive control) 57.2. Histological evaluation of the 3D cell cultures showed no severe toxicity or loss of viability for any of the wires. However, relative comparison between the different wires revealed that stainless steel induced less toxicity/loss of viability compared with TMA and Nitinol wire.

PMID: 16901961 [PubMed - indexed for MEDLINE]

A modified double pedicle graft technique and other mucogingival interceptive surgeries for the management of impacted teeth: a case series.

Indian J Dent Res. 2006 Jan-Mar;17(1):35-9

Authors: Sunil S, Avinash BS, Prasad D, Jagadish L

Maxillary canine is one of the most common teeth that are impacted. This accounts for 1-2% of all patients who attend orthodontic treatment. The key to achieve maximal eruption of these teeth is their surgical exposure and the role of periodontist in such situations is to provide a functional and satisfactory width of attached gingiva on the labial surface. There are different techniques to surgically expose the impacted teeth, namely--gingivectomy technique, apically positioned flap, closed eruption technique, modified apically positioned flap, double pedicle flap and free gingival graft. Selection of the procedure is dependent on the positioning of the tooth in relation to mucogingival junction and attached gingiva. In the present case series we describe three different techniques for uncovering of impacted teeth, which are apically positioned flap, closed eruption technique and a modified double pedicle graft specially planned for the situation. These procedures when selected diligently using sound selection criteria will create adequate width of attached gingiva which minimizes or eliminates the future mucogingival problems.

PMID: 16900893 [PubMed - indexed for MEDLINE]

The benefits of aesthetic orthodontic brackets in patients requiring multiple MRI scanning.

J Orthod. 2006 Jun;33(2):90-4

Authors: Harris TM, Faridrad MR, Dickson JA

MRI scans are increasingly used diagnostically in medicine. Scans of the head and neck region can be distorted by metallic components in the vicinity. This paper discusses the consideration for aesthetic brackets (with no metal components) on all teeth including molars in patients requiring MRI scans and especially if those need to be repeated on a regular basis.

PMID: 16751430 [PubMed - indexed for MEDLINE]

BOS MOrth Cases Prize 2004.

J Orthod. 2006 Mar;33(1):7-21

Authors: U&#xFF;s JO

This paper describes the clinical orthodontic treatment of 2 cases that were successfully entered for the 2004 American Orthodontics MOrth Cases Prize. The first case is that of a patient presenting with a Class III malocclusion treated with rapid maxillary expansion and protraction headgear followed by fixed appliance therapy. The second case demonstrates the use of fixed appliances to correct a moderate Class II division I malocclusion.

PMID: 16514129 [PubMed - indexed for MEDLINE]

Galvanic corrosion between orthodontic wires and brackets in fluoride mouthwashes.

Eur J Orthod. 2006 Jun;28(3):298-304

Authors: Schiff N, Boinet M, Morgon L, Lissac M, Dalard F, Grosgogeat B

The aim of this investigation was to determine the influence of fluoride in certain mouthwashes on the risk of corrosion through galvanic coupling of orthodontic wires and brackets. Two titanium alloy wires, nickel-titanium (NiTi) and copper-nickel-titanium (CuNiTi), and the three most commonly used brackets, titanium (Ti), iron-chromium-nickel (FeCrNi) and cobalt-chromium (CoCr), were tested in a reference solution of Fusayama-Meyer artificial saliva and in two commercially available fluoride (250 ppm) mouthwashes, Elmex and Meridol. Corrosion resistance was assessed by inductively coupled plasma-atomic emission spectrometry (ICP-MS), analysis of released metal ions, and a scanning electron microscope (SEM) study of the metal surfaces after immersion of different wire-bracket pairs in the test solutions. The study was completed by an electrochemical analysis. Meridol mouthwash, which contains stannous fluoride, was the solution in which the NiTi wires coupled with the different brackets showed the highest corrosion risk, while in Elmex mouthwash, which contains sodium fluoride, the CuNiTi wires presented the highest corrosion risk. Such corrosion has two consequences: deterioration in mechanical performance of the wire-bracket system, which would negatively affect the final aesthetic result, and the risk of local allergic reactions caused by released Ni ions. The results suggest that mouthwashes should be prescribed according to the orthodontic materials used. A new type of mouthwash for use during orthodontic therapy could be an interesting development in this field.

PMID: 16428255 [PubMed - indexed for MEDLINE]

Observations on the use and clinical effectiveness of lacebacks.

J Orthod. 2005 Dec;32(4):294-5; author relpy 295-6

Authors: Bennett J

PMID: 16333051 [PubMed - indexed for MEDLINE]

Clinical pearl: clinical tips with System-R.

J Orthod. 2005 Dec;32(4):244-6

Authors: Parkin N

The article describes the versatility and ease of use of a relatively new bracket system manufactured by GAC called System-R. This system consists of two bracket types; standard width and reduced width, both of which have an active self-ligating clip. The reduced friction offered by this system allows different mechanics to be employed. Security of ligation and absence of decaying force values allows longer treatment intervals. Fast and reliable opening and closing of the clips means reduced chairside time. Difficulties experienced personally by these brackets are highlighted and some troubleshooting tips are included.

PMID: 16333045 [PubMed - indexed for MEDLINE]

Rescue surgery (surgical repositioning) of impacted lower second molars.

Med Oral Patol Oral Cir Bucal. 2005 Nov-Dec;10(5):448-53

Authors: Garc&#xED;a-Calderón M, Torres-Lagares D, González-Martín M, Gutiérrez-Pérez JL

The impaction of lower second molars, given that its incidence is 0.03 to 0.21%, is a rare complication in tooth eruption. It has been detected more often in unilateral form than bilateral and is more common in the mandible than in the maxillary. It has a slight predilection for males, and mesial inclination is more usual. A wide variety of therapeutic approaches have been published, basically referring to surgical techniques, independent or complemented by means of orthodontic technical aids, with the aim of placing the tooth in the correct position, and which are encompassed under the concept of surgical rescue. In cases resolved with repositioning of an impacted tooth, prophylactic root extraction has been proposed as obligatory. We present a case of a 12 and a half year old patient referred to the University of Seville due to non-eruption of the left lower second molar. The patient was referred by her orthodontist, who detected the impaction before starting orthodontic treatment. The orthodontist requested that, if it was possible, we did not extract the root of the third molar, because its eruption would be feasible in the future (there would be sufficient space in the arch). The spaces available were measured and we decided to attempt the repositioning of the impacted tooth without extracting the root of the wisdom tooth, which was carried out successfully.

PMID: 16264380 [PubMed - indexed for MEDLINE]

How does temperature influence the properties of rectangular nickel-titanium wires?

Eur J Orthod. 2006 Jun;28(3):282-91

Authors: Sakima MT, Dalstra M, Melsen B

Thermodynamic nickel-titanium (NiTi) wires have become increasingly popular. The relationship between the temperature variation within the mouth and the force level delivered is, however, far from elucidated. The aim of this study was to evaluate the influence of possible intraoral temperature differences on the forces exerted by seven commercially available 0.019 x 0.025 inch NiTi archwires. As mouth temperature ranges from 33 to 37 degrees C most of the time, all wires were tested at five different temperatures between 30 and 40 degrees C in an orthodontic wire-testing device, a so-called Force System Identification (FSI) apparatus, placed in a climate chamber. In the FSI a two-bracket system using self-ligating Damon brackets simulated first order displacements up to 4 mm. At each temperature five samples of each archwire brand were tested. The following variables from the activation/deactivation curves were calculated: force and displacement at the yield point, maximum force level, total energy up to maximum displacement, energy loss after deactivation, force and displacement at the beginning and at the finish of the plateau, and the slope of the plateau. Any statistically significant differences in these variables for the different brands and temperature levels were analysed using one-way analysis of variance. The results showed that: (1) The behaviour of all wires was different. (2) Copper NiTi40 showed the lowest and the most constant force level, followed by NeoSentalloy 200 g. On the other hand, these wires may not work properly in mouth breathers as no forces were exerted below 35 degrees C. (3) If the use of superelastic characteristics and low force levels are the reasons for utilizing rectangular NiTi wires, austenitic NiTi wires should be avoided.

PMID: 16199409 [PubMed - indexed for MEDLINE]

How to ... place a lower bonded retainer.

J Orthod. 2005 Sep;32(3):206-10

Authors: Shah AA, Sandler PJ, Murray AM

Post-orthodontic relapse of lower incisors is a common phenomenon. Sometimes a bonded retainer is fitted to prevent this relapse. In this article, we suggest a handy clinical technique of fitting a lower bonded retainer, which is convenient and easy to carry out.

PMID: 16170063 [PubMed - indexed for MEDLINE]

Clinical pearl In-treatment replacement of missing incisors.

J Orthod. 2005 Sep;32(3):182-4

Authors: Hodge TM

Four methods of in-treatment replacement of missing incisors are described.

PMID: 16170059 [PubMed - indexed for MEDLINE]

Ion release and cytotoxicity of stainless steel wires.

Eur J Orthod. 2005 Dec;27(6):533-40

Authors: Oh KT, Kim KN

Heat treatment is generally applied to orthodontic stainless steel (SS) wires to relieve the stresses that result from their manipulation by orthodontists. The quality and thickness of the oxide films formed on the surface of heat-treated wires can vary, and it is believed that these oxide films can influence the properties of heat-treated wires. The aim of this study was to investigate the influence of heat treatment and cooling methods on the amount of metal ions released and to examine the cytotoxicity of heat-treated wires. In this study, four types of SS wires (Remanium, Permachrome, Colboloy and Orthos) with a cross-sectional area of 0.41 x 0.56 mm were investigated. These wires were heat-treated in a vacuum, air, or argon environment, and were cooled in either a furnace or a water bath. Four control groups and 24 experimental groups were classified according to the type of wires, heat treatment conditions and cooling methods. In each group, the amount of nickel released as well as its cytotoxicity was investigated. The concentration of dissolved nickel ions in artificial saliva was measured for a period of up to 12 weeks. In all groups, the concentration of dissolved nickel ions in artificial saliva was lowest for the vacuum heat treatment-furnace cooling group and a significant difference was shown compared with the other experimental groups. The concentration of dissolved nickel ions in artificial saliva was highest in the groups heat-treated in air (P < 0.05), while the amount of nickel released was highest in the Remanium and Colboloy (P < 0.05). The cytotoxicity was mild in all the experimental groups but the response index of the air groups was slightly higher than in the other groups. According to these results, SS wires retain their high corrosion resistance and low ion release rate when heat-treated in a vacuum and cooled in a furnace.

PMID: 16093259 [PubMed - indexed for MEDLINE]

Evolution of flexural rigidity according to the cross-sectional dimension of a superelastic nickel titanium orthodontic wire.

Eur J Orthod. 2005 Aug;27(4):402-7

Authors: Garrec P, Tavernier B, Jordan L

The choice of the most suitable orthodontic wire for each stage of treatment requires estimation of the forces generated. In theory, the selection of wire sequences should initially utilize a lower flexural rigidity; thus clinicians use smaller round cross-sectional dimension wires to generate lighter forces during the preliminary alignment stage. This assessment is true for conventional alloys, but not necessarily for superelastic nickel titanium (NiTi). In this case, the flexural rigidity dependence on cross-sectional dimension differs from the linear elasticity prediction because of the martensitic transformation process. It decreases with increasing deflection and this phenomenon is accentuated in the unloading process. This behaviour should lead us to consider differently the biomechanical approach to orthodontic treatment.The present study compared bending in 10 archwires made from NiTi orthodontics alloy of two cross-sectional dimensions. The results were based on microstructural and mechanical investigations. With conventional alloys, the flexural rigidity was constant for each wire and increased largely with the cross-sectional dimension for the same strain. With NiTi alloys, the flexural rigidity is not constant and the influence of size was not as important as it should be. This result can be explained by the non-constant elastic modulus during the martensite transformation process. Thus, in some cases, treatment can begin with full-size (rectangular) wires that nearly fill the bracket slot with a force application deemed to be physiologically desirable for tooth movement and compatible with patient comfort.

PMID: 16043477 [PubMed - indexed for MEDLINE]

An in vitro comparison of the shear bond strength of a resin-reinforced glass ionomer cement and a composite adhesive for bonding orthodontic brackets.

Eur J Orthod. 2005 Oct;27(5):477-83

Authors: Movahhed HZ, Ogaard B, Syverud M

The shear bond strength (SBS) of a light-cured, resin-reinforced glass ionomer and a composite adhesive in combination with a self-etching primer was compared after different setting times to evaluate when orthodontic wires could be placed. Additionally, the fracture site after debonding was assessed using the Adhesive Remnant Index (ARI). Eighty freshly extracted human premolars were used. Twenty teeth were randomly assigned to each of four groups: (1) brackets bonded with Transbond XT with a Transbond Plus etching primer and debonded within 5 minutes; (2) brackets bonded with Fuji Ortho LC and debonded within 5 minutes; (3) brackets bonded as for group 1 and debonded within 15 minutes; (4) brackets bonded as for group 2 and debonded within 15 minutes. The SBS of each sample was determined with an Instron machine. The mean SBS were, respectively: (1) 8.8 +/- 2 MPa; (2) 6.6 +/- 2.5 MPa; (3) 11 +/- 1.6 MPa and (4) 9.6 +/- 1.6 MPa. Interpolating the cumulative fracture probability by means of a Weibull analysis, the 10 per cent probabilities of fracture for the groups were found to be attained for shear stresses of 6.1, 3.1, 8.3 and 7.1 MPa, respectively. Chi-square testing of the ARI scores revealed that the nature of the remnant did not vary significantly with time, but the type of bonding material could generally be distinguished in leaving more or less than 10 per cent of bonding material on the tooth. After debonding, the Transbond system was likely to leave adhesive on at least 10 per cent of the bonded area of the tooth. The present findings indicate that brackets bonded with either Transbond XT in combination with Transbond Plus etching primer and Fuji Ortho LC had adequate bond strength at 5 minutes and were even stronger 15 minutes after initial bonding.

PMID: 16043469 [PubMed - indexed for MEDLINE]

British Orthodontic Society, Chapman Prize Winner 2003. A novel in vitro culture model to investigate the reaction of the dentine-pulp complex to orthodontic force.

J Orthod. 2005 Jun;32(2):122-32

Authors: Dhopatkar AA, Sloan AJ, Rock WP, Cooper PR, Smith AJ

OBJECTIVE: To develop a novel mandible slice organ culture model to investigate the effects of externally applied force on the dentine-pulp complex. DESIGN: In vitro organ culture. SETTING: School of Dentistry, Birmingham, UK. MATERIALS AND METHODS: Transverse 2 mm thick sections were cut from the mandibles of five 28-day-old male Wistar rats. Serial sections were used for control and test pairs. Springs made from 0.016-inch and 0.019 x 0.025-inch stainless steel wires were used to apply a 50 g tensile or compressive force, respectively, to test specimens. Control and test specimens were cultured for 5 days in a humidified incubator with 5% CO(2) at 37 degrees C and processed for routine histological investigation. Nine more rats were used to provide control and compression test pairs where the pulps were extirpated after 3 days culture and total RNA isolated for gene expression analysis by reverse transcriptase polymerase chain reaction (RT-PCR). RESULTS: Histology showed the dental and supporting tissues maintained a healthy appearance in the control cultures after culture. Histomorphometric analysis revealed a 20-27% increase in pulp fibroblast density in test specimens compared with controls. Gene expression analyses revealed up-regulation in the test groups of PCNA, c-Myc, Collagen 1alpha, TGF-beta1 and alkaline phosphatase, whilst expression of osteocalcin was reduced. CONCLUSIONS: The results demonstrated that the present organ culture technique provides a valuable in vitro experimental model for studying the effects of externally applied forces. These forces stimulated a cellular response in the pulp chamber characterized by altered gene expression and proliferation of fibroblasts; the latter being unaffected by the nature of the force in terms of compression or tension.

PMID: 15994986 [PubMed - indexed for MEDLINE]

Archwire seating forces produced by different ligation methods and their effect on frictional resistance.

Eur J Orthod. 2005 Jun;27(3):302-8

Authors: Khambay B, Millett D, McHugh S

The aims of this study were to determine the mean tensile force of four different elastomeric modules, the archwire seating force of different ligation methods, and its effect on frictional resistance.To determine the mean tensile force, each elastomeric module (purple, grey, Alastik, and SuperSlick) was extended by 5 mm using two hooks attached to a load cell using a Nene M3000 testing machine. To assess the median archwire seating force, a maxillary premolar bracket (3M Unitek) was welded to a sheet of stainless steel (SS) and glued to a Perspex block. The bracket base was removed and the cut continued into the Perspex below. A length of test wire was taken and bent to form a "U" shape, with the middle portion 20 mm in length. The free ends of the wire were secured to the load cell of the Nene testing machine. Two wire sizes were tested, 0.017 x 0.025 and 0.019 x 0.025 inch SS. The load cell was activated and the force with which the wire was displaced into the slot by the ligation method was measured. Four types of elastomeric module were tested together with a pre-formed 0.09 inch SS ligature. The experimental method used to determine the mean frictional force of each module and wire size was carried out using a method described previously.Statistically significant differences existed in the mean tensile forces and median archwire seating forces between the elastomeric modules. Grey modules with either size wire produced the lowest median archwire seating force, whereas SS ligatures produced the highest forces. SS ligatures with either wire produced the lowest mean frictional forces, whereas grey modules produced significantly higher mean frictional force (P < 0.01). The force with which the wire was seated into the bracket did not seem to be related to the subsequent amount of mean frictional force produced.

PMID: 15947232 [PubMed - indexed for MEDLINE]

A stainless steel bracket for orthodontic application.

Eur J Orthod. 2005 Jun;27(3):237-44

Authors: Oh KT, Choo SU, Kim KM, Kim KN

Aesthetics has become an essential element when choosing orthodontic fixed appliances. Most metallic brackets used in orthodontic therapy are made from stainless steel (SS) with the appropriate physical properties and good corrosion resistance, and are available as types 304, 316 and 17-4 PH SS. However, localized corrosion of these materials can frequently occur in the oral environment. This study was undertaken to evaluate the accuracy of sizing, microstructure, hardness, corrosion resistance, frictional resistance and cytotoxicity of commercially available Mini-diamond (S17400), Archist (S30403) and experimentally manufactured SR-50A (S32050) brackets.The size accuracy of Mini-diamond was the highest at all locations except for the external horizontal width of the tie wing (P < 0.05). Micrographs of the Mini-diamond and Archist showed precipitates in the grains and around their boundaries. SR-50A showed the only austenitic phase and the highest polarization resistance of the tested samples. SR-50A also had the highest corrosion resistance [SR-50A, Mini-diamond and Archist were 0.9 x 10(-3), 3.7 x 10(-3), and 7.4 x 10(-3) mm per year (mpy), respectively], in the artificial saliva. The frictional force of SR-50A decreased over time, but that of Mini-diamond and Archist increased. Therefore, SR-50A is believed to have better frictional properties to orthodontic wire than Mini-diamond and Archist. Cytotoxic results showed that the response index of SR-50A was 0/1 (mild), Mini-diamond 1/1 (mild+), and Archist 1/2 (mild+). SR-50A showed greater biocompatibility than either Mini-diamond or Archist.It is concluded that the SR-50A bracket has good frictional property, corrosion resistance and biocompatibility with a lower probability of allergic reaction, compared with conventionally used SS brackets.

PMID: 15947222 [PubMed - indexed for MEDLINE]

An innovative adhesive procedure for connecting transpalatal arches with palatal implants.

Eur J Orthod. 2005 Jun;27(3):226-30

Authors: Crismani AG, Bernhart T, Bantleon HP, Kucher G

The aim of this presentation is to describe an innovative adhesive procedure for connecting palatal implants with transpalatal arches (TPAs). The steps required for completing the procedure, the costs involved and the requisite time were reviewed and compared with those of two alternative procedures reported in the literature. To establish the stability and reliability of the procedure in vitro, tensile stress tests were performed. The results were evaluated in view of a potential loss of anchorage and compared with reported data.The innovative adhesive procedure ensured a stable and precise connection between TPAs and palatal implants during a single visit in a chair-side time of 42 minutes. The costs incurred were euro 12.33. The composite-connected component parts resisted breakage up to a mean force of 3323.16 cN. Absolute stability of the TPA-palatal implant connection in terms of maximal anchorage was limited to a mean force of 408.05 cN at a wire strength of 0.036 inches.

PMID: 15947220 [PubMed - indexed for MEDLINE]

The variable anchorage straight wire technique compared with the straight wire technique in deep overbite correction.

Eur J Orthod. 2005 Apr;27(2):180-5

Authors: Banaie F, Parikakis K, Moberg S, Hellsing E

The aim of this retrospective study was to compare the treatment results and the number of required treatment appointments between the variable anchorage straight wire technique (VAST) and the straight wire (SW) technique. The subjects were 53 Caucasian patients of both sexes (25 males and 28 females, mean age 13.5 years at the start of treatment), with an overjet > or = 4 mm and an overbite > or = 3 mm. The patients were divided into four groups, VAST (n = 31) or SW (n = 22), extraction or non-extraction, and were treated by the same orthodontist. Variables from two lateral cephalograms obtained before and at the completion of active treatment, and the number of scheduled appointments were compared between the two techniques.The main difference between the two techniques was the bracket design. With the VAST, the bracket allowed both tipping and parallel movements with the possibility to combine double archwires. Due to the influence of the Begg technique, no extra-oral traction was needed in the VAST groups and Class II elastics were used at the start of treatment.Both techniques seemed to produce equal treatment results. However, in this study, it was shown that in deep overbite correction, the VAST required fewer scheduled appointments than the SW technique.

PMID: 15817626 [PubMed - indexed for MEDLINE]

Straight talk on braces.

FDA Consum. 2005 Jan-Feb;39(1):20-6

Authors: Bren L

PMID: 15803592 [PubMed - indexed for MEDLINE]

A randomized controlled trial comparing the quadhelix and the expansion arch for the correction of crossbite.

J Orthod. 2005 Mar;32(1):29-35

Authors: McNally MR, Spary DJ, Rock WP

OBJECTIVE: To compare the use of the quadhelix and the expansion arch for the correction of crossbite. DESIGN: A prospective randomized clinical trial supported by preliminary laboratory measurements. The null hypothesis was that there was no difference in the clinical effectiveness of the two expansion devices in terms of crossbite correction. SETTING: Queen's Hospital, Burton on Trent and The University of Birmingham, School of Dentistry.Participants: The first 60 patients on the orthodontic waiting list at Queen's Hospital who required expansion of the maxillary arch as part of the treatment plan were allocated to be treated with either a quadhelix or an expansion arch by random allocation. Twenty-eight and 27 members of each respective group completed the study. MATERIALS: Commercial quadhelix arches (3M Unitek) and custom-made expansion arches METHODS: The force produced by the type of expansion arches used in the study was measured in the laboratory to be 1.8 N at 10 mm of expansion. Quadhelix arches of sizes 2 and 3 were found to produce equivalent forces at 5 and 7 mm of expansion respectively. Either expansion device was fitted to the 60 participants according to random allocation and expanded by the standard amount. Intermolar and intercanine expansion was measured after 4, 8 and 12 weeks. Patient opinion was assessed by using a questionnaire. RESULTS: The quadhelix and the expansion arch were equally effective in producing expansion (p>0.05). After 12 weeks, the two types of archwire had produced mean intermolar expansions of 4.54 and 5.09 mm and intercanine expansions of 1.41 and 2.12 mm, respectively. Both types of arch were reported as uncomfortable by a majority of patients, the quadhelix affected mainly the tongue and the expansion arch the cheeks. The appearance of the quadhelix was disliked by 25% of participants, while 70% disliked the expansion arch. CONCLUSIONS: The null hypothesis was confirmed. However, the expansion arch had several advantages that made it a cheap alternative to the quadhelix for crossbite expansion, because it can be made and fitted at the chairside.

PMID: 15784941 [PubMed - indexed for MEDLINE]

Influence of autoclave sterilization on the surface parameters and mechanical properties of six orthodontic wires.

Eur J Orthod. 2005 Feb;27(1):72-81

Authors: Pernier C, Grosgogeat B, Ponsonnet L, Benay G, Lissac M

Orthodontic wires are frequently packaged in individual sealed bags in order to avoid cross-contamination. The instructions on the wrapper generally advise autoclave sterilization of the package and its contents if additional protection is desired. However, sterilization can modify the surface parameters and the mechanical properties of many types of material.The aim of this research was to determine the influence of one of the most widely used sterilization processes, autoclaving (18 minutes at 134 degrees C, as recommended by the French Ministry of Health), on the surface parameters and mechanical properties of six wires currently used in orthodontics (one stainless steel alloy: Tru-Chrome RMO; two nickel-titanium shape memory alloys: Neo Sentalloy and Neo Sentalloy with Ionguard GAC; and three titanium-molybdenum alloys: TMA(R) and Low Friction TMA Ormco and Resolve GAC).The alloys were analysed on receipt and after sterilization, using surface structure observation techniques, including optical, scanning electron and atomic force microscopy and profilometry. The mechanical properties were assessed by three-point bending tests.The results showed that autoclave sterilization had no adverse effects on the surface parameters or on the selected mechanical properties. This supports the possibility for practitioners to systematically sterilize wires before placing them in the oral environment.

PMID: 15743866 [PubMed - indexed for MEDLINE]

Factors influencing the wearing of protective gloves in orthodontic practice.

Eur J Orthod. 2005 Feb;27(1):64-71

Authors: Cheng HC, Lee SY, Chou HY

The purpose of this study was to explore how wearing, or not wearing, protective gloves affects the efficiency of orthodontists in performing certain orthodontic procedures. Thirty-six volunteers were randomly selected from members of the Taiwan Association of Orthodontists. A visual analogue scale (VAS) was used to determine the degree of convenience subjects felt in performing 11 specified orthodontic procedures, with and without gloves. In addition, the time required to bend round and rectangular archwires and to tie and untie ligature wires was recorded.The results showed that for 10 of the 11 orthodontic tasks there was perceived to be no difference when wearing, or not wearing, gloves. Only when bending a round archwire was there perceived to be a difference. When the four orthodontic procedures were undertaken on a typodont and timed, no significant difference was found between the use of gloves/no gloves.

PMID: 15743865 [PubMed - indexed for MEDLINE]

Soluble cytokine receptor treatment in experimental orthodontic tooth movement in the rat.

Eur J Orthod. 2005 Feb;27(1):1-11

Authors: J&#xE4;ger A, Zhang D, Kawarizadeh A, Tolba R, Braumann B, Lossdörfer S, Götz W

Pro-inflammatory cytokines, such as interleukin-1 (IL-1) and tumour necrosis factor-alpha (TNF-alpha), are believed to play a role in the biological processes involved in the course of orthodontic tooth movement and especially in root resorption. The inhibition of cytokine activity, e.g. by soluble receptors, could be beneficial in reducing this unwanted side-effect.The aim of this study was to investigate the role of cytokines IL-1 and TNF-alpha in the course of experimentally induced tooth movement. The upper left first molar was moved orthodontically in 80 male Wistar rats using a coil spring with a force of 0.5 N. Starting at day -1, three groups of 20 animals each received daily intraperitoneal injections (ip) of 2 ml of 1 mug/ml soluble receptors (a) to IL-1(sIL-RII), (b) to TNF-alpha (sTNF-alpha-RI) and (c) a combination of (a) and (b). Twenty animals served as the control. After 3, 6, 9 and 12 days, the animals were killed in groups of five. The amount of tooth movement was registered and the maxillae were prepared for histological and histomorphometric analysis. Osteoclasts and odontoclasts were identified using tartrate-resistant acid phosphatase (TRAP) histochemistry.The amount of tooth movement was reduced in all receptor-treated groups by approximately 50 per cent. At the same time, the number of TRAP-positive cells on the desmodontal bone surface and on the surface of the roots was reduced. Thus, systemic application of soluble receptors to IL-1 and TNF-alpha following experimental induction of tooth movement in the rat reduced the number of osteoclasts as well as odontoclasts.

PMID: 15743857 [PubMed - indexed for MEDLINE]

Factors affecting friction in the pre-adjusted appliance.

Eur J Orthod. 2004 Dec;26(6):579-83

Authors: Moore MM, Harrington E, Rock WP

A jig was constructed to measure the frictional forces created by various tip and torque values in association with two types of straightwire bracket moving along tainless steel (SS) archwires. Forces were measured during translation of the bracket using an Instron machine. Steel and cobalt chromium brackets were tested in association with 0.019 x 0.025 and 0.021 x 0.025 inch steel archwires at tips from 0 to 3 degrees and torque values in 2 degree increments from 0 to 6 degrees.The mean values for static (2.2 N) and kinetic (2.1 N) friction were very similar (P = 0.71), as were the overall friction values for stainless steel (2.1 N) and chromium cobalt (2.2 N) brackets of similar dimensions (P = 0.44). Use of 0.021 x 0.025 inch wire produced three times as much friction as 0.019 x 0.025 inch wire, 3.0 N against 1.2 N (P < 0.01). Increased tip and torque were associated with highly significant increases in friction (P < 0.01). Every degree of tip produced approximately twice as much friction as comparable torque. The main conclusion of the study was that space closure should be completed on a 0.019 x 0.025 inch archwire before a 0.021 x 0.025 inch wire is used to complete tooth alignment.

PMID: 15650066 [PubMed - indexed for MEDLINE]

The effectiveness of laceback ligatures: a randomized controlled clinical trial.

J Orthod. 2004 Dec;31(4):303-11; discussion 300

Authors: Irvine R, Power S, McDonald F

OBJECTIVE: To evaluate the effects of laceback ligatures on the anteroposterior and vertical position of lower incisors and the mesial position of the lower first molars. DESIGN: Randomized controlled trial. SETTINGS: Patients under treatment in the Department of Orthodontics, Royal Bournemouth Hospital, Dorset, during a 6 month period from November 1999 to March 2000. SUBJECTS: Sixty-two adolescents (mean 13.7 years, range 11.2-16.8 years) with similar malocclusions, requiring extraction of all first premolars, were randomly assigned to experimental (laceback: 30; 12 male, 18 female) and control (non-laceback: 32; 14 male, 18 female) groups. INTERVENTIONS: Treatment using upper and lower fixed appliances following extraction of four premolars. One group had lacebacks placed, whilst the control group had no lacebacks. MAIN OUTCOME MEASURES: The participants were examined clinically and radiographically, and lateral cephalograms with radio-opaque tooth markers and lower study casts records were taken when lower fixed appliances were placed (T1) and following sufficient leveling with a 0.018 inch stainless steel round wire (T2). Linear measurements were recorded following digitization of the lateral cephalograms and using a vernier caliper on the study casts. A Student t-test was used to examine differences between the two groups following assessment for normality. RESULTS: In both groups the lower incisors retroclined during T1-T2; (Mean+/-SD: Experimental -0.53+/-1.9 mm, Control -0.44+/-1.29 mm). There was no statistical significance between the two groups (p = 0.84). The lower incisors extruded in both groups; 0.47+/-0.98 mm in the experimental group and 0.44+/-0.87 mm in the control group. There was no statistical difference between the groups (p = 0.9). The lower first molars showed 0.83 mm greater mesial movement in the experimental group, which was statistically significant (p < 0.05). Labial segment crowding decreased in both groups (experimental -3+/-1.6 mm, control -2.67+/-2.28 mm), the difference between the groups being non-significant (p = 0.51). Arch length decreased in both groups (experimental -2.08+/-2.82 mm , control -2.9+/-3.06 mm), but the difference between them was not significant (p = 0.28) CONCLUSIONS: In first premolar extraction cases, the lower labial segment does not procline during the leveling stage with the pre-adjusted edgewise appliance and the use of laceback ligatures conveys no difference in the anteroposterior or vertical position of the lower labial segment. Furthermore, the use of laceback ligatures creates a statistically and clinically significant increase in the loss of posterior anchorage.

PMID: 15608345 [PubMed - indexed for MEDLINE]

Clinical management in extraction cases using palatal implant for anchorage.

J Orthod. 2004 Dec;31(4):288-94

Authors: Giancotti A, Greco M, Mampieri G, Arcuri C

This case report presents a Class I extraction treatment in an adult patient with bimaxillary crowding using a palatal implant for anchorage control. The implant (pure titanium 6 mm SLA) is inserted in the middle of the palate, after a careful radiological assessment on a lateral cephalogram. At the end of the healing period (13 weeks), an anchorage device, such as a squared trans-palatal bar connecting the maxillary molars to the palatal implant, is projected and placed in order to obtain the posterior anchorage control. The orthodontic treatment was performed according to the bidimensional technique.

PMID: 15608343 [PubMed - indexed for MEDLINE]

How to effectively use a 2 x 4 appliance.

J Orthod. 2004 Sep;31(3):248-58

Authors: Dowsing P, Sandler PJ

A mixed dentition treatment can efficiently and effectively be provided using a 2 x 4 appliance. The indications for early treatment are discussed and advantages of fixed appliances over traditionally used removable appliances illustrated using four case reports.

PMID: 15489369 [PubMed - indexed for MEDLINE]

In vitro cytotoxicity of orthodontic archwires in cortical cell cultures.

Eur J Orthod. 2004 Aug;26(4):421-6

Authors: David A, Lobner D

There have been a number of studies regarding the toxicity of orthodontic archwires, but little is known concerning the mechanism of their toxicity. This investigation used murine cortical cell cultures to examine the in vitro neurotoxicity of commonly used orthodontic metallic archwire alloys. The materials examined included 0.016 inch nickel-titanium (NiTi), copper-nickel-titanium, titanium-molybdenum, Elgiloy, and stainless steel archwire alloys. Standard sized samples of each material were placed on tissue culture inserts suspended above the cell cultures. Neuronal death was determined using the lactate dehydrogenase release assay 24 hours after exposure to the archwires. The results indicated that NiTi, copper-nickel-titanium and titanium-molybdenum alloys were not neurotoxic, while stainless steel and Elgiloy were significantly toxic. Washing the archwires for 7 days in a saline solution did not alter the toxicity. However, the free radical scavenger, trolox, blocked the toxicity of both stainless steel and Elgiloy, indicating that the death was free radical mediated. The caspase inhibitor, Z-VAl-Ala-Asp-fluoromethylketone (zVAD-FMK), blocked the toxicity of stainless steel, but not Elgiloy, suggesting that stainless steel induced apoptosis. Further evidence that stainless steel induced apoptosis was provided by propidium staining which showed nuclear chromatin condensation and fragmentation into discrete spherical or irregular shapes, characteristic of apoptosis. The specific metal responsible for the toxicity was not determined; the metals common to each of the toxic archwires were nickel, iron, and chromium.

PMID: 15366387 [PubMed - indexed for MEDLINE]

[The effects of combined reverse Nance and TPA on reinforcement of anchorage]

Shanghai Kou Qiang Yi Xue. 2004 Aug;13(4):262-5

Authors: Chen W, Chen RJ, Shen G

PURPOSE: To evaluate the effects of combined reverse Nance and TPA on anchorage control. METHODS: 16 female adults with Class II division 1 malocclusion were treated with the combined mechanism of reverse Nance and TPA in an attempt to reinforce molar anchorage. Cephalometric analysis and model measurements were conducted for the assessment of anchorage control. RESULTS: The mesial movement of the upper first molars were minimized within 1/5 extracted space, parameters such as UMVD, MP-FH, ANS-Me remained unchanged, indicating the molar anchorage was controlled effectively. CONCLUSION: The modified combination of reverse Nance and TPA might be effective in anchorage forcement.

PMID: 15349660 [PubMed - indexed for MEDLINE]

Three-dimensional finite element analysis in distal en masse movement of the maxillary dentition with the multiloop edgewise archwire.

Eur J Orthod. 2004 Jun;26(3):339-45

Authors: Chang YI, Shin SJ, Baek SH

The purpose of this study was to compare the effects of a multiloop edgewise archwire (MEAW) on distal en masse movement with a continuous plain ideal archwire (IA). Three-dimensional finite element models (FEM) of the maxillary dentition in which the second permanent molars had been extracted were constructed to include the periodontal membrane, alveolar bone, standard edgewise bracket (0.018 x 0.025 inch), stainless steel IA (0.016 x 0.022 inch), and MEAW (0.016 x 0.022 inch). The stress distribution and displacement of the maxillary dentition were analysed when Class II intermaxillary elastics (300 g/side) and 5 degree tip-back bends were applied to the IA and MEAW for distal en masse movement of the maxillary dentition. Compared with the IA, the MEAW showed that the discrepancy in the amount of tooth displacement was lower and individual tooth movement was more uniform and balanced. There was minimal vertical displacement or rotation of the teeth using the MEAW when compared with the IA. The MEAW seems to have advantages for distal en masse movement of the maxillary dentition.

PMID: 15222721 [PubMed - indexed for MEDLINE]

Evaluation of methods of archwire ligation on frictional resistance.

Eur J Orthod. 2004 Jun;26(3):327-32

Authors: Khambay B, Millett D, McHugh S

The aim of the study was to investigate the effect of elastomeric type and stainless steel (SS) ligation on frictional resistance using a validated method. To assess the validity of the new test system to measure mean frictional forces, SS and TMA wires, each with dimensions of 0.017 x 0.025 and 0.019 x 0.025 inches, were used in combination with a self-ligating Damon II bracket or a conventional preadjusted edgewise premolar SS bracket without ligation. Four types of elastomeric module, purple, grey, Alastik or SuperSlick, and a pre-formed 0.09 inch SS ligature were then assessed as methods of ligation using preadjusted edgewise premolar SS brackets. The specimens were tested on a Nene M3000 testing machine, with a crosshead speed of 5 mm/minute and each test run lasted for 4 minutes. Each bracket/wire combination with each method of ligation was tested 10 times in the presence of human saliva and the mean frictional force was recorded. The mean frictional forces were compared using three-way analysis of variance. The Damon II self-ligating bracket and unligated conventional SS bracket produced negligible mean frictional forces with any of the wires tested. For the 0.017 x 0.025 SS, 0.019 x 0.025 SS or 0.019 x 0.025 inch TMA wires, SS ligatures produced the lowest mean frictional forces. With the 0.017 x 0.025 TMA wire, purple modules produced the lowest mean frictional force. There was no consistent pattern in the mean frictional forces across the various combinations of wire type, size and ligation method. Under the conditions of this experiment, the use of passive self-ligating brackets is the only method of almost eliminating friction.

PMID: 15222719 [PubMed - indexed for MEDLINE]

[Orthodontic wires in a simulated oral environment:change in mechanical properties]

Shanghai Kou Qiang Yi Xue. 1997 Sep;6(3):159-62

Authors: Tang GH, Liu K, Cao HJ, Lu J, Zhang CW

In this study,some different kinds of orthodontic archwires were tested to evaluate the changes of their mechanical properties.The results showed that in oral environment,all wires suffered degradation of their properties:the force-generating capacity decreased and the permanent deformation increased.The force-generating capacity decreased and the permanent deformation increased.The force decay resulted mainly from the tooth movement.The deformation occurred within 7 days.Chinese-NiTi alloy suffered less stress-relaxation and residual deformation than the stainless steel wires.Arch wires with vertical loops showed similar properties with NiTi,which could deliver more constant force.

PMID: 15160221 [PubMed - as supplied by publisher]

[Properies of orthodontic wires in simulated teeth alignment test]

Shanghai Kou Qiang Yi Xue. 1997 Sep;6(3):156-8

Authors: Tang GH, Liu K, Cao HJ, Lu J, Zhang CW

In this study,methods were developed to test and compare leveling archwires that commonly used in domestic practice.The results showed that the stainless steel arch wires were stiff.The Ni-Ti wires and the wires with loops were flexible and could deliver more constant force.The 0.014 Chinese Ni-Ti wires demonstrated the superelastic property,but 0.016 Ni-Ti wire did not appear the same property before they generated 250g force.

PMID: 15160220 [PubMed - as supplied by publisher]

A clinical study of glass ionomer cement.

Eur J Orthod. 2004 Apr;26(2):185-9

Authors: Oliveira SR, Rosenbach G, Brunhard IH, Almeida MA, Chevitarese O

The aim of this investigation was to compare the clinical performance of a glass ionomer cement (GIC) with a composite resin when used for direct bonding of standard edgewise orthodontic brackets. Fourteen patients (10 females, four males), in whom 242 teeth were bonded with brackets, were divided into two groups: GIC (121 teeth) and composite (121 teeth). The brackets were allocated to alternate quadrants and first-time failures were recorded over a period of 24 months. Data were analysed statistically (non-parametric chi-squared test). The results demonstrated a significantly lower unpreviewed debonding index (UDI) (15.7 per cent) for the composite than for the GIC (28.1 per cent) (P = 0.042). The use of heavy archwires was largely responsible for this difference. No difference was observed when light and medium archwires were used. GIC may be a viable alternative to composite for use with light archwires and with limited treatment objectives.

PMID: 15130042 [PubMed - indexed for MEDLINE]

Dynamic frictional behaviour of orthodontic archwires and brackets.

Eur J Orthod. 2004 Apr;26(2):163-70

Authors: Clocheret K, Willems G, Carels C, Celis JP

The aim of this study was to evaluate the frictional behaviour of 15 different archwires and 16 different brackets using small oscillating displacements when opposed to a standard stainless steel bracket or a standard stainless steel wire. Tests were run according to a pilot study at a frequency of 1 Hz and with a reciprocating tangential displacement of 200 microm, while the wire remained centred in the bracket slot under a load of 2 N. The results indicated a significant difference between the evaluated wires and brackets. The mean coefficient of friction (COF) of the wires varied from 0.16 for Imagination NiTi tooth-coloured wire to 0.69 for the True Chrome Resilient Purple wire, while for the brackets it ranged from 0.39 for Ultratrimm to 0.72 for the Master Series. The fact that in this study, a large number of different commercially available archwires and brackets were evaluated with the same apparatus according to the same protocol, allows a direct comparison of the different archwire and bracket combinations, and can assist in the choice of the optimal bracket-wire combination with regard to friction.

PMID: 15130039 [PubMed - indexed for MEDLINE]

Orthodontic palatal implants: clinical technique.

J Orthod. 2004 Mar;31(1):3-8

Authors: Tinsley D, O'Dwyer JJ, Benson PE, Doyle PT, Sandler J

The aim of this paper is to familiarize the readers with some of the clinical considerations necessary to ensure successful use of mid-palatal implants. Both surgical and technical aspects will be discussed along with a description of impression techniques used.

PMID: 15071143 [PubMed - indexed for MEDLINE]

A comparative study of the static and kinetic frictional resistance of titanium molybdenum alloy archwires in stainless steel brackets.

Eur J Orthod. 2004 Feb;26(1):105-11

Authors: Cash A, Curtis R, Garrigia-Majo D, McDonald F

This ex vivo study compared the static and kinetic frictional resistance of eight different archwires tested in a single, stainless steel, zero base 0.022 x 0.028 inch (0.56 x 0.711 mm) slot standard edgewise bracket. The archwires evaluated were 0.019 x 0.025 inch (0.483 x 0.636 mm) in dimension, manufactured from the following alloys: beta titanium (TMA), 'low friction' coloured beta titanium (aqua, honeydew, purple and violet), ion-implanted beta titanium, Timolium and a stainless steel control. Prior to friction testing, bracket and archwire dimensions were measured by direct digital imaging via a desktop computer linked to a binocular light microscope. Frictional force was evaluated using an Instron universal testing machine. All experiments were carried out at room temperature, with no ligation, in the dry state with 20 degrees of added torque. The results demonstrated that static and kinetic friction were statistically significant (P < 0.001) for all archwire types. Ion-implanted and standard TMA archwires were found to have no significant advantage over stainless steel. The archwire alloys may be ranked as follows: stainless steel produced the lowest frictional resistance followed by honeydew, ion-implanted TMA and Timolium, with aqua, purple and violet producing frictional resistance values as high as standard TMA. It was also found that the percentage difference between the archwire and bracket slot dimensions claimed by the manufacturers and those measured in this experiment produced tolerances ranging from +5.37 to -6.67 per cent.

PMID: 14994890 [PubMed - indexed for MEDLINE]

Perception of pain during orthodontic treatment with fixed appliances.

Eur J Orthod. 2004 Feb;26(1):79-85

Authors: Erdin&#xE7; AM, Dinçer B

The aims of this study were to investigate the initial time at which pain occurs after insertion of two initial wires of different sizes, the duration of the pain, the areas affected within the mouth, the level of self-medication, the effect of this pain on daily life, and whether gender is important in the perception of pain. The study group consisted of 109 patients (52 boys, 57 girls) with a mean chronological age of 13.6 years for boys and 14.7 years for girls. Insertion of either a 0.014 or 0.016 inch wire was by random selection. Following insertion of the archwires, a questionnaire comprising a total of 49 questions was given to the patients. They described the time of initial pain in the first question, answered the next 24 questions as 'yes' or 'no', and used a visual analogue scale for the final 24 questions. No significant differences were found in terms of gender, in the perception period of initial pain as regards the areas affected within the mouth or the effect of pain on daily living when the 0.014 and 0.016 inch wire groups were compared at 6 hours, 1, 2, 3, 4, 5, 6 and 7 days. At 24 hours, which was found to be statistically significant, more pain relief was used in the 0.014 inch archwire group. The results show that in both groups, initial pain was perceived at 2 hours, peaked at 24 hours and had decreased by day 3.

PMID: 14994886 [PubMed - indexed for MEDLINE]

[Developing a straight wire bracket placement gauge]

Shanghai Kou Qiang Yi Xue. 2003 Oct;12(5):349-51

Authors: Shi L, Liu DX, Wang RY

OBJECTIVE: To develop a new straight wire bracket placement gauge, providing measurement instrument for it's accurate position. Methods The gauge was made of 3.0 mm x 6.0 mm stainless steel, after being curved in certain form, made by machine process and cleaned through removing tough and polishing. The bracket placement gauge is divided into three parts: the middle straight stem, the curve head and the measurement head. It was 146 mm long, the angle between straight stem and curve was 145 degrees,the angle between the curve and measurement head was 105 degrees.The measurement head was made of occlusion placement item and slot placement item. The occlusion placement item was 10 mm long and 2 mm thick. The slot placement item was 2 mm long and 0.4 mm thick. This suit of gauge had 7 pieces, the measurement scope was 2.5 mm-5.5 mm which reflected the different vertical distances from occlusion edge to the middle point of slot. RESULTS: This gauge can determine the vertical position of bracket. CONCLUSION: The gauge improve the accuracy with individual straight wire bracket position table.

PMID: 14966609 [PubMed - indexed for MEDLINE]

The load/deflection characteristics of thermally activated orthodontic archwires.

Eur J Orthod. 2003 Aug;25(4):417-21

Authors: Parvizi F, Rock WP

The objective of the study was to investigate the load/deflection characteristics of three commercially available thermally active nickel-titanium orthodontic archwires using a standard nickel-titanium archwire as a control. The thermally active wires were Regency Thermal, Orthoform, and Eurotherm and the control was Memory. Round 0.4 mm and rectangular 0.4 x 0.56 mm wires were subjected to 2 and 4 mm of deflection in a water bath at temperatures of 20, 30, and 40 degrees C and forces were measured in three-point bend and phantom head situations. Analysis of variance revealed that, irrespective of the test set up and wire type, wire size had a significant effect (P < 0.001) on the forces produced. An increase in size from 0.4 mm round to 0.4 x 0.56 mm rectangular wire approximately doubled the force values for a given deflection. The effect of wire deflection on the force values varied according to the test system, forces being much higher in the phantom head tests than in the beam tests. In the beam tests, an increase in wire deflection from 2 to 4 mm had no significant effect on the forces exerted, but in the phantom head tests the forces produced by each wire at 4 mm deflection were four to five times greater than those at 2 mm deflection. Each of the thermally active wires produced less force that the non-thermally active wire. However, there was a large variation between the three types of thermally active wire. In the beam tests each 10 degrees C rise in temperature from 20 to 40 degrees C had a highly significant effect on the force produced by each thermoelastic wire (P < 0.001). In the phantom head tests there were significant force increases between 20 and 30 degrees C (P < 0.001), but between 30 and 40 degrees C the forces did not change significantly.

PMID: 12938849 [PubMed - indexed for MEDLINE]

Constant versus dissipating forces in orthodontics: the effect on initial tooth movement and root resorption.

Eur J Orthod. 2003 Aug;25(4):335-42

Authors: Weiland F

The aim of this clinical and confocal laser scanning microscopic study was to compare the effects of two frequently used archwires on tooth movement and root resorption. A total of 84 premolars in 27 individuals (10 boys, 17 girls, with a mean age of 12.5 years) was moved buccally with an experimental fixed orthodontic appliance. In a split mouth experimental design the premolar on one side was activated with a stainless steel wire with a buccal offset of 1 mm, which was reactivated every four weeks and the contralateral premolar was moved with a superelastic wire with a force plateau of 0.8-1 N. This wire had an initial activation of 4.5 mm and was not reactivated during the 12-week experimental period. At the end of the experimental period the teeth were extracted. Six premolars were used as control teeth and were extracted before the experiment started. Tooth displacement was studied three-dimensionally on dental casts with a co-ordinate measuring machine. The depth, perimeter, area, and volume of the resorption lacunae was measured using three-dimensional digital images made with a confocal laser scanning microscope (CLSM). On these images the resorbed portions of the root surface were 'reconstructed' mathematically. The results show that the teeth activated with the superelastic wire moved significantly more than the teeth with the steel wire during the experimental period. The depth of the resorption lacunae did not differ significantly between the groups; however, perimeter, area, and volume of the resorption lacunae on the teeth of the 'superelastic group' were 140 per cent greater than on the teeth of the 'steel group'. It may be concluded that a greater amount of tooth movement occurred with superelastic wires, offering a force level of 0.8-1 N compared with stainless steel wires, with initially higher but rapidly declining forces in an experimental set up for a period of 12 weeks. The amount of root resorption was significantly larger in the superelastic group.

PMID: 12938838 [PubMed - indexed for MEDLINE]

Nickel allergy and orthodontics.

J Orthod. 2003 Jun;30(2):171-4

Authors: Rahilly G, Price N

Nickel is the most common metal to cause contact dermatitis in orthodontics. Nickel-containing metal alloys, such as nickel-titanium and stainless steel, are widely used in orthodontic appliances. Nickel-titanium alloys may have nickel content in excess of 50 per cent and can thus potentially release enough nickel in the oral environment to elicit manifestations of an allergic reaction. Stainless steel has a lower nickel content (8 per cent). However, because the nickel is bound in a crystal lattice it is not available to react. Stainless steel orthodontic components are therefore very unlikely to cause nickel hypersensitivity. This article discusses the diagnosis of nickel allergy in orthodontics and describes alternative products that are nickel free or have a very low nickel content, which would be appropriate to use in patients diagnosed with a nickel allergy.

PMID: 12835436 [PubMed - indexed for MEDLINE]

Root resorption related to hypofunctional periodontium in experimental tooth movement.

J Dent Res. 2003 Jun;82(6):486-90

Authors: Sringkarnboriboon S, Matsumoto Y, Soma K

Orthodontic movement of non-occluding teeth may result in undesirable apical root resorption. These teeth present with a histologically altered periodontium and are considered to be hypofunctional. The purpose of this study was to compare the amount of root resorption associated with a normal and a hypofunctional periodontium in rats during experimental tooth movement caused by heavy continuous force. The mandibular first molar was induced into a non-occluding condition in the hypofunctional periodontium group. Mesial orthodontic force was applied by means of 50-gram-force closed-coil springs for 15 days in both groups. The active root-resorption lacunae from histological sections, identified by tartrate-resistant acid phosphatase, were measured in terms of length, depth, and area. The results showed that the amount of root resorption was significantly greater in teeth with a hypofunctional periodontium than in those with a normal periodontium (p < 0.05). These results suggest that orthodontic movement of non-occluding teeth should be performed with caution.

PMID: 12766204 [PubMed - indexed for MEDLINE]

The effect of prostaglandin E2 and calcium gluconate on orthodontic tooth movement and root resorption in rats.

Eur J Orthod. 2003 Apr;25(2):199-204

Authors: Seifi M, Eslami B, Saffar AS

Possible modifications in orthodontic tooth movement (OTM) and root resorption as a result of local injections of prostaglandin E2 (PGE2) alone and with calcium gluconate (Ca) formed the aim of the present study. Twenty-four 8-week-old male Wistar rats were selected and randomly divided into three groups of eight. Both quadrants of the upper jaws of the first group of animals were used; therefore this group comprised two groups: control and normal. The upper left first molars of these eight animals were not placed under orthodontic force and received no injection, to serve as the normal group, considered for root resorption comparison only. The control group had localized submucosal injections of normal saline on the buccal side of the upper right first molar. In the third group, 0.1 ml of 1 mg/ml PGE2 was injected at the same site and the fourth group received an intraperitoneal injection of 200 mg/kg Ca (10%) in addition to the PGE2. All the injections were performed on days 0 and 7. The orthodontic appliance consisted of a closed coil spring ligated to the upper right first molar and incisor, exerting a force of 60 g during the 21-day experimental period, after which the animals were sacrificed. Palatal halves were removed for histological examination and for calculation of the amount of root resorption. Statistical analysis of data showed a significant (P < 0.05) acceleration in OTM after PGE2 injection compared with the control group. The addition of Ca reduced OTM but a significant increase (P< 0.05) was still recorded. A significant difference (P < 0.05) in root resorption was only observed between the PGE2 and normal groups. The findings show the importance of calcium ions working in association with PGE2 in stabilizing root resorption while significantly increasing OTM.

PMID: 12737218 [PubMed - indexed for MEDLINE]

Photo-elastic stress analysis of initial alignment archwires.

Eur J Orthod. 2003 Apr;25(2):117-25

Authors: Badran SA, Orr JF, Stevenson M, Burden DJ

Photo-elastic models replicating a lower arch with a moderate degree of lower incisor crowding and a palatally displaced maxillary canine were used to evaluate the stresses transmitted to the roots of the teeth by initial alignment archwires. Six initial alignment archwires were compared, two multi-strand stainless steel wires, two non-super-elastic (stabilized martensitic form) nickel titanium wires, and two stress-induced super-elastic (austenitic active) nickel titanium wires. Three specimens of each archwire type were tested. Analysis of the photo-elastic fringe patterns, in the medium supporting the teeth, revealed that the non-super-elastic nickel titanium archwires produced the highest shear stresses (P = 0.001). However, the shear stresses generated by the super-elastic alignment archwires and the multi-strand stainless steel archwires were very similar (P = 1.00). These results show that even in situations where large deflections of initial alignment archwires are required, super-elastic archwires do not appear to have any marked advantage over multi-strand stainless steel alignment archwires in terms of the stresses transferred to the roots of the teeth.

PMID: 12737209 [PubMed - indexed for MEDLINE]

Broken orthodontic trans-palatal archwire stuck to the throat of orthodontic patient: is it strange?

J Orthod. 2003 Mar;30(1):11

Authors: Abdel-Kader HM

Trans-palatal arch wire is in common use in orthodontic practice. This case report of broken trans-palatal wire, swallowed and stuck to the throat of an orthodontic patient, is presented in the hope that it will stress the importance of careful examination of the appliance at each scheduled visit.

PMID: 12644601 [PubMed - indexed for MEDLINE]