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PubMed2004

Influence of fluoridated mouthwashes on corrosion resistance of orthodontics wires.

The aim of the present study was to classify the different alloys commonly used to make orthodontic wire according to their corrosion resistance in different media. The four materials analysed were titanium-based alloys: TMA, TiNb, NiTi and CuNiTi, which were tested in three fluoride mouthwashes: Elmex, Meridol and Acorea as well as in Fusayama Meyer artificial saliva. The electrochemical study showed that the alloys could be divided into two groups. In one group were the NiTi-based alloys which were subject to strong corrosion in the presence of monofluorophosphate found in Acorea solution. In the other group were TiNb, which was the most resistant to corrosion, and TMA, which corroded strongly with the stannous fluoride found in Meridol mouthwash. The results obtained in the present study will enable us to provide attending practitioners with advice concerning fluoride mouthwash to recommend, depending on the treatment phase and the alloy used. So we can advise Elmex mouthwash for patients with TMA and NiTi-based orthodontics wires but we suggest Acorea or Meridol mouthwashes for patients with TiNb orthodontics wires.

Corrosion↗
PubMed2005

Comparison of the finite helical axis and the rectangular coordinate system in representing orthodontic tooth movement.

In orthodontics, tooth movement is typically described using the rectangular coordinate system (XYZ); however, this system has several disadvantages when performing biomechanical analyses. An alternative method is the finite helical axis (FHA) system, which describes movement as a rotation about and a translation along a single axis located in space. The purpose of this study was to examine differences between the FHA and the XYZ systems in analyzing orthodontic tooth movement. Maxillary canine retraction was done using sliding mechanics or a retraction spring with midpalatal orthodontic implants used as measuring references. Tooth movement calculated with the FHA was compared with the corresponding movement in the rectangular coordinate system weekly over a 2-month interval in eight patients. The FHA showed that sliding mechanics controlled rotation of the canine better than the retraction spring (Ricketts retractor), and that the Ricketts retractor controlled tipping better. Changes in the FHA direction and position vectors with time showed that the biomechanical forces are not uniform during the treatment period. In both mechanics, the FHA provided a simple biomechanical model for canine retraction.

Adult↗
PubMed2006

Pain discomfort and crevicular fluid changes induced by orthodontic elastic separators in children.

UNLABELLED: The objective of the present investigation was to study the experience of pain after placement of orthodontic elastic separators and the possible associations with the gingival crevicular fluid (GCF) composition changes at the level of interleukin 1-beta (IL-1beta), substance P (SP), and prostaglandin-E2 (PGE2). Eighteen children (mean age 10.8 yrs) in the beginning of the orthodontic treatment were included. Molar elastic separators were inserted mesially to 2 first upper or lower molars. One of the antagonist molars served as control. The GCF was collected from the distobuccal and distopalatal sites from each molar, before (day -7, day 0) and after the placement of separators (1 h, day 1, and day 7). Pain intensity was recorded using a visual analog scale (VAS). The contents of IL-1beta, SP, and PGE2 were determined by enzyme-linked immunosorbent assay. Pain intensity increased after 1 h (VAS = 11) and remained high on day 1 (VAS = 13). On day 7, no significant pain was reported. After 1 h, 1 day, and 7 days, mean GCF IL-1beta levels were significantly elevated at treatment teeth compared to control teeth (highest day 1). The GCF levels of SP and PGE2 for the treatment teeth were significantly higher at day 1 and day 7 than the control teeth. All 3 mediators remained at baseline levels throughout the experiment for the control teeth. The intensity of pain at 1 h was associated to PGE2 levels (R2 = 0.38; P < .05), whereas at day 1, the intensity of pain was associated to IL-1beta levels (R2 = 0.63, P < .0001). Thus, we report a rapid release of biochemical markers (1 h) that peaked after 1 day and partially decreased 7 days later. The intensity of pain followed a similar pattern. Associations were found between the experience of pain intensity and the GCF mediator levels. PERSPECTIVE: The study may help to detect, in an initial stage, individuals prone to perceive higher level of pain during orthodontic treatment. This may help in the development of methods that will better control and/or alleviate the discomfort of pain during tooth movement.

Adolescent↗
PubMed2004

A similarity function to evaluate the orthodontic condition in patients with cleft lip and palate.

The objective of this work is the modeling of a similarity function adapted to the medical environment using the logical-combinatorial approach of pattern recognition theory, and its application to compare the orthodontic conditions of patients with cleft-primary palate and/or cleft-secondary palate congenital malformations. The variables in domains with no a priori algebraic or topological structure are objects whose similarity or difference is evaluated by comparison criteria functions. The range of these functions is an ordered set normalized into the unit interval, and they are designed to allow differentiation and non-uniform treatment of the object-variables. The analogy between objects is formalized as a similarity function that stresses the relations among the comparison criteria and evaluates the partial descriptions (partial similarity/difference) or total descriptions (total similarity/difference) of the objects. For the orthodontic problem we defined a set of 12 variables featuring the unilateral/bilateral fissures, the conditions of maxilla, premaxilla, mandible and patient's bite. The comparison criteria (logical for malocclusion, fuzzy for maxillary collapse unilateral/anteroposterior and for overbite, and Boolean for protrusive/retrusive premaxilla conditions) were assigned a relevance factor based on the orthodontist accumulated knowledge and experience. The modeling of the similarity function and its effectiveness in comparing orthodontic conditions in patients are illustrated by the study of four clinical cases with different clefts. The results through similarity are close to the expected ones. Moreover evaluated at different moments it allows to assess the effect of treatment in a single patient, hence providing valuable auxiliary criteria for medical decision making as to the patient's rehabilitation. We include the potential extension of the methodology to other medical disciplines such as speech therapy and reconstructive surgery.

Algorithms↗
PubMed2002

Successful treatment of orthodontic-associated traumatic endophthalmitis.

PURPOSE: To report successful management of orthodontic-associated traumatic endophthalmitis. DESIGN: Interventional case report. METHODS: A 17-year-old boy developed endophthalmitis after a penetrating corneal injury produced during removal of an orthodontic wire. Treatment included pars plana vitrectomy (PPV) with broad-spectrum intravitreal and systemic antibiotics. RESULTS: Clinical endophthalmitis resolved after PPV with injection of intravitreal vancomycin (1 mg) and ceftazidime (2.25 mg), along with oral ciprofloxacin (750 mg twice daily). Microbiologic cultures of intraocular samples produced Staphylococcus epidermidis, Streptococcus viridans, and Lactobacillus species. Visual acuity improved to 20/20. CONCLUSIONS: Orthodontic-associated endophthalmitis can involve multiple organisms. It can be successfully treated with current treatment modalities, including PPV, intravitreal antibiotics, and systemic antibiotics.

Adolescent↗
PubMed1977

An evaluation of silicophosphate as an orthodontic cement.

In a laboratory and clinical evluation, when used for the cementation of orthodontic bands, a zinc silicophosphate cement has proved to be comparable to zinc phosphate cement in its bond strength to enamel. This was demonstrated in laboratory tests by higher values being required to break the mechanical bond and in the clinical study by the slightly smaller percentage of bands which became loose during orthodontic treatment. In both the laboratory and clinical studies it was found that silicophosphate remained attached to the enamel in higher percentages after a band had become loose. It also was found that the remaining cement was often quite difficult to remove from the enamel. Probably the greatest advantage of using silicophosphate is that no decalcification of enamel was found under bands which had become loose during orthodontic treatment. This may be attributable to the higher bond strength and/or the presence of fluoride in the cement. Further clinical studies of this nature appear warranted.

Dental Bonding↗
PubMed1983

Surface distribution of enamel opacities following orthodontic treatment.

A cross-sectional study was carried out to determine the prevalence and severity of enamel opacities occurring on different surfaces of the dentition as well as the distribution of these lesions on individual teeth following orthodontic treatment. The sample consisted of 527 patients examined prior to and 269 other patients examined after completion of multibanded orthodontic treatment. The results showed that following orthodontic treatment there was a significant increase in the prevalence of enamel opacities on the vestibular and lingual surfaces of the dentition. The increase was significantly greater on the cervical and middle thirds of the crown. Among individual teeth, there was a statistically significant increase in the prevalence and severity of enamel opacities on the maxillary and mandibular first molars, the maxillary lateral incisors, and the mandibular lateral incisors and canines. The increase was greatest on the cervical and middle thirds of the vestibular surface of these teeth.

Adolescent↗
PubMed1983

"Single-step" orthodontic bonding systems: possible mutagenic potential.

Six commercially available orthodontic direct-bonding resin systems used to attach orthodontic brackets to tooth enamel were tested for bacterial mutagenicity by means of the Ames test. Components of two systems were found to yield positive spot test results with strains of Salmonella typhimurium. Positive spot test results were also obtained on the components applied to orthodontic brackets. Dose response curves for components of these systems were determined for aqueous and DMSO extracts using strain TA-100.

Dental Bonding↗
PubMed1985

Periodontal complication during orthodontic therapy. A case report.

Occasionally periodontal complications arise during adult orthodontic therapy, although conditions may also occur in adolescent patients. This case report describes the periodontal condition that developed during orthodontic treatment of an adolescent girl. Eleven months after the start of treatment, an unusual hyperplastic soft-tissue lesion developed that did not respond to conservative treatment. The case history, orthodontic treatment, periodontal treatment, histopathology, and follow-up are described. Suggestions for prevention and early diagnosis of similar problems are reviewed since particular periodontal infections may progress subclinically.

Adolescent↗
PubMed1985

A reassessment of force magnitude in orthodontics.

The relationship between the force magnitude delivered by orthodontic appliances and the rate of orthodontic tooth movement is controversial. This paper critically reviews the experimental data base that has shaped this controversy and graphically presents four hypotheses proposed to represent the relationship between force magnitude and the rate of tooth movement. The clinical implications of each hypothesis for treatment planning and space-closing mechanics are discussed. The authors' analysis of the data from six heavily cited clinical studies in the orthodontic literature appears to support one of the four proposed hypotheses (No. 4, Fig. 2). Acceptance of this hypothesis leads the clinician to a rational approach in manipulating the final position of teeth. Anchorage can be conserved by means of treatment strategies that reduce stress magnitudes in the periodontium of the posterior teeth while maximally efficient stress is maintained on the anterior teeth. Appliances with low load-deflection rates and relatively constant moment/force ratios allow the clinician to take advantage of the type of tooth movement proposed in this hypothesis.

Biomechanical Phenomena↗
PubMed2003

Angiogenic growth factors released in human dental pulp following orthodontic force.

OBJECTIVE: The aim of this study was to investigate if a combination of five diffusible angiogenic growth factors were released in human dental pulp during orthodontic force application, by using growth factor neutralising antibodies (NAs) to block their effects. MATERIALS AND METHODS: Dental pulps from 18 premolar teeth treated with orthodontic fixed appliances for 2 weeks were divided vertically, and each half pulp further sectioned and co-cultured with a section of rat aorta in collagen surrounded by growth media. NAs (anti-h VEGF, anti-h FGF2, anti-h PDGF, anti-TGFbeta and anti-h EGF) were added to the media of the co-cultures from one half of each pulp from 10 teeth. The co-cultures from the remaining eight teeth acted as controls. Sections of rat aorta alone were also cultured with and without NAs. Cultures were examined daily by light microscopy for growth and number of microvessels. RESULTS: NAs significantly reduced microvessel numbers in the co-cultures, but not in the rat aorta alone cultures. CONCLUSIONS: The results show that a combination of these angiogenic growth factors are released in the pulp following orthodontic force.

Adolescent↗
PubMed1993

Histomorphometric study of dental pulp during orthodontic tooth movement.

Orthodontic tooth movement has been implicated in secondary changes to the dental pulp. The purpose of this study was to correlate the effects of orthodontic tooth movement on the dental pulp by histomorphometric parameters. Four groups, each consisting of 36 male adult Sprague-Dawley strain rats, were studied with differing force magnitudes. These included a sham group in addition to groups with bilaterally placed appliances activated to 20, 40, and 60 g of initial force designed to mesially tip the maxillary first molars. Six rats were killed at 1, 3, 5, 7, 10, and 14 days. Specimens were fixed, embedded, and stained with tetrachrome. Pulpal measurements were made with an image analyzer and included changes in predentin and vascularity. Findings indicated a significant increase (p < or = 0.05) relative to time and force magnitude in capillary number. An initial pulpal hyperemia was observed following activation of orthodontic force which was unrelated to force magnitude. A force-dependent increase in predentin width was measured at the peak of the tooth movement cycle.

Animals↗
PubMed2003

An optimized synthetic substrate for orthodontic bond strength testing.

OBJECTIVE: The purpose of this study was to investigate the suitability of different synthetic calcium phosphate based substrates as a biomimetic enamel surface model for orthodontic bond strength testing. METHODS: Carbonated apatite, amorphous calcium phosphate and commercial hydroxyapatite specimens were prepared as substrates for orthodontic bond strength testing. Carbonated apatite specimens were prepared by pressing, sintering and treatment with NaF. The shear bond strength was measured with a universal testing machine. RESULTS: Hydroxyapatite, amorphous and cold pressed carbonated hydroxyapatite exhibited fractures within the substrate after debonding. Mean bond strength values for carbonated hydroxyapatite were 7.38 (1.75) MPa for specimens pressed at 300 degrees C and 9.55 (2.23) MPa for specimens pressed at 300 degrees C and then sintered at 600 degrees C. An additional NaF treatment after sintering resulted in lower bond strength measurements of on average 6.52 (1.03) MPa. SIGNIFICANCE: Hot pressed and sintered carbonated hydroxyapatite showed acceptable shear bond strength values and may represent a suitable biomimetic model for orthodontic bond strength testing.

Apatites↗
PubMed2003

Ion release from NiTi orthodontic wires in artificial saliva with various acidities.

NiTi orthodontic wire products from different manufacturers would have different corrosion resistance. We assayed the corrosion resistance, in terms of ion release, of different NiTi orthodontic wires in artificial saliva with various acidities. Four types of as-received commercial NiTi orthodontic wires were immersed in artificial saliva (37 degrees C) at pH 2.5-6.25 for different periods (1-28d). The amount of Ni and Ti ions released from NiTi wires was determined using an atomic adsorption spectrophotometer. Surface morphology and roughness of wires were related to the corrosion resistance. Results showed that the manufacturer, pH value, and immersion period, respectively, had a significantly statistical influence on the release amount of Ni and Ti ions. The amount of Ni ions released in all test solutions was well below the critical value necessary to induce allergy and below daily dietary intake level. The amount of Ti ions released in pH>/=3.75 solution was mostly not detectable, representing that the TiO(2) film on NiTi wires exhibited a good protection against corrosion. Pre-existed surface defects on NiTi wires might be the preferred locations for corrosion. The NiTi wire with the highest release amount of metal ions had the maximal increase in surface roughness after immersion test, while a rougher surface did not correspond to a higher metal ion release.

Corrosion↗
PubMed2003

Orthodontic preparation for orthognathic surgery: how long does it take and why? A retrospective study.

We investigated the duration of pre-operative orthodontic treatment of patients who had combined orthodontic and orthognathic treatment and examined the variables that influenced this. Records of patients who had undergone such treatment in the past 5 years were collected (n=65) from three consultant orthodontists and one Senior Specialist Registrar/Fixed Term Training Appointment (FTTA). The number of days from placement of the first active orthodontic component to the day that final planning impressions were taken was used to calculate the duration of treatment before the patient was ready for operation. The variables investigated were: sex, age, malocclusion, extractions (excluding third molars), and the clinician. The median duration of pre-operative treatment was 17 months (range 7-47). Only the orthodontist appeared to affect this duration, but this requires further investigation as it may merely reflect variation in other factors such as compliance. We conclude that patients should be informed that the pre-operative phase may last 12-24 months.

Adolescent↗
PubMed1999

Third molar management: a case for routine removal in adolescent and young adult orthodontic patients.

The role of the orthodontist is to treat patients to optimal function, aesthetics, and long-term stability. The controversy surrounding third molars has focused on the pathologic problems they may cause and the risk/benefits of their removal. Although malocclusion is not considered a disease, it is unreasonable to ignore the orthodontic issues related to third molars, especially in patients who make the investment to achieve an ideal occlusion. Part of a complete orthodontic treatment plan is a recommendation regarding third molars. The plan should include a rationale and recommendation for their removal based on the orthodontic treatment objectives.

Adolescent↗
PubMedDate not supplied

In vitro peel/shear bond strength of orthodontic adhesives.

OBJECTIVES: The purpose of this study was to evaluate the in vitro peel/shear bond strength of a selection of orthodontic bracket adhesives to human premolar teeth. METHODS: Twenty-two commercially available bracket adhesives were used to bond the same bracket type (Miniature Twin, 3M Unitek, Monrovia, CA. USA) on 264 intact human premolar teeth and then adhesively tested to failure. Peel/shear bond strength values were calculated in newtons and megapascals. The site of bond failure was scored according to the Adhesive Remnant Index. Statistics included one-way analysis of variance and Tukey's Studentized Range test together with Weibull analysis. The latter is a survival analysis able to describe the performance of a material. RESULTS: The mean bond strengths varied from 9.9 MPa for Concise to 4.1 MPa for Heliosit Orthodontic. The overall F-test showed a significant difference (P < 0.0001). No significant differences in bond strength were found between Concise, AccuBond, Imperva Dual, Transbond XT, Kurasper and Spectrum. CONCLUSION: Concise and AccuBond are among the materials of choice for bonding fixed orthodontic appliances to teeth. These materials combine high bond strength with a reliable bond that is easily and quickly debonded.

Acrylic Resins↗
PubMed1999

Fluoride release from orthodontic bonding agents: a comparison of three in vitro models.

The aim of this in vitro study was to compare fluoride release from two cement disc models (partially varnished and unvarnished) of three orthodontic bonding materials with fluoride release from the same materials when used to bond an orthodontic bracket onto a tooth surface. A resin-modified glass ionomer cement (Vitremer) and a compomer material (Dyract Ortho) were compared with a conventional resin adhesive (Right-On). Ten discs (3.0 mm diameter and 1.5 mm thick) of each material were manufactured in a silicone mould and ten premolar teeth were bonded with orthodontic brackets using each material. All the premolar teeth were covered with nail varnish up to the bracket periphery and five of the discs for each material were coated with nail varnish on both upper and lower surfaces which halved the surface area. The fluoride released into 2 ml of deionised water, from each tooth or disc, was measured at regular intervals over 60 days. At 60 days, cumulative fluoride release was highest from the unvarnished discs, less for the varnished discs and least from the tooth-bracket model for both test materials. Despite having twice the surface area, the unvarnished disc model released only 1.2 to 1.5 times more fluoride than the varnished disc model. Compared with the tooth-bracket model, the unvarnished discs released 3.0 to 4.5 times more fluoride, whereas the varnished discs released only 2.2 to 3.7 times more fluoride. For the materials tested in this study, halving the surface of the discs did not reduce the cumulative fluoride release by half. The tooth/bracket model with minimal bonding material demonstrated substantial cumulative fluoride release. The pattern of fluoride release was similar for all models tested.

Analysis of Variance↗