Evaluation of corrosion resistance and surface characteristics of orthodontic wires immersed in different mouthwashes.

BACKGROUND: Patients use mouthwashes in addition to mechanical cleaning during orthodontic treatment. The effects of mouthwashes on the archwires have not been examined yet. OBJECTIVE: To compare the corrosion resistance of four different arch wires and corrosion effects of different mouthwashes to formulate a biocompatible and mechanically useful arch wire and mouthwash combination. METHODS: Each group comprised of 4 wire samples of 2 cm 0.016 × 0.022 inch. 1st group: ion implanted nickel titanium (INT), 2nd group: nickel titanium, without ion implantation (NT), 3rd group: micro layered esthetic nickel titanium (ENT), 4th group: stainless steel (SS) wires. They were immersed inside 2 ml of artificial saliva solutions (AS) for the control, or AS (9%) combined with 1 of the 3 mouthwashes (91%) for study groups, for 24 hours. These mouthwashes were essential oil (EO), chlorhexidine (CHX), sodium-fluoride (NaF). An electrochemical analyzer was used for electrochemical impedance spectroscopy measurements. RESULTS: High corrosion resistance was obtained for ENT than the other wires. The corrosion potentials are 0.007, -0.042, 0.074 and -0.015 V (Ag/AgCl) for ENT, INT, SS and NT in the artificial salivary, respectively. In NaF containing mouthwash Rp value of ENT is significantly high in comparison to others. The impedance responses of all materials increased significantly in the presence of NaF mouthwash as well as in the CHX mouthwash. Low frequencies are seen at all materials in EO mouthwash. Diameters of loops are 22, 5.9, 5.9 and 3.7 MΩ at ENT, INT, SS and NT. CONCLUSIONS: In this study, micro layered esthetic nickel titanium wires are found biocompatible among other wires and NaF and CHX mouthwashes can be recommend for their good corrosion resistance during fixed orthodontic therapy.

Landmark errors on posteroanterior cephalograms.

INTRODUCTION: It is important to reduce the method errors when evaluating posteroanterior cephalograms to see either small deviations from normal or transverse changes caused by orthodontic treatment. The aim of this study was to determine horizontal and vertical intraexaminer and interexaminer agreement in localization of landmarks in posteroanterior cephalograms of adult patients. METHODS: The sample was gathered retrospectively from the archives of the Department of Orthodontics of Yeditepe University in Istanbul, Turkey. Radiographs of 39 patients diagnosed with skeletal asymmetries (20 women, 19 men) were drawn manually, and a coordinate system was established with software. The tracings were made by 2 operators, after a calibration session on 29 landmarks (22 bilateral, 7 midline). Intraclass correlation coefficients and the Bland-Altman test were used for detecting interexaminer and intraexaminer agreement for each cephalometric variable. RESULTS: The interexaminer agreement test showed that the most problematic landmark was crista galli, which showed moderate consistency between 2 examiners in the y coordinates at 2 time points. Condylar and zygomatic landmarks showed good agreement. The greater wing inferior and superior orbit, maxillary point, menton, anterior nasal spine, antegonial notch, mandibular and maxillary molar point, maxillary and mandibular incisor point, and maxillary and mandibular incisor edge landmarks had excellent agreement between the 2 examiners at the 2 time points in both the x and y coordinates. CONCLUSIONS: There are fewer errors in intraexaminer than in interexaminer correlations in landmark identifications on posteroanterior radiographs. All landmarks investigated except crista galli showed good agreement between measurements.

Maxillary buccal cortical plate inclination at mini-screw insertion sites.

OBJECTIVE: To evaluate whether buccal cortical bone inclination varies for the maxillary alveolar processes of adult patients with decreased, normal, and increased facial heights. MATERIALS AND METHODS: Cone-beam computed tomography images of 135 adult patients, including 49 hypodivergent subjects (26 women, 23 men), 40 hyperdivergent subjects (24 women, 16 men), and 46 normodivergent (25 women, 21 men) were analyzed. Cortical bone inclination measurements were made relative to the occlusal plane. Cross-sectional slices of the maxilla were taken at interdental sites from the distal aspect of maxillary canine to the mesial aspect of maxillary second molar. RESULTS: Analysis of variance indicated significant differences (P < .05) between the angles formed by the line tangent to the cortical bone and the occlusal plane among the vertical facial types for the regions between canine and first premolar and between second premolar and first molar at miniscrew insertion sites. CONCLUSION: The results of this study indicate that vertical facial pattern should be taken into consideration when adjusting the insertion angle of miniscrews at the maxillary buccal region.

Metal ion release from silver soldering and laser welding caused by different types of mouthwash.

OBJECTIVE: To compare metal ion release from samples welded with silver soldering and laser welding when immersed into mouthwashes with different ingredients. MATERIALS AND METHODS: A total of 72 samples were prepared: 36 laser welded and 36 silver soldered. Four samples were chosen from each subgroup to study the morphologic changes on their surfaces via scanning electron microscopy (SEM). Each group was further divided into four groups where the samples were submerged into mouthwash containing sodium fluoride (NaF), mouthwash containing sodium fluoride + alcohol (NaF + alcohol), mouthwash containing chlorhexidine (CHX), or artificial saliva (AS) for 24 hours and removed thereafter. Subsequently, the metal ion release from the samples was measured with inductively coupled plasma mass spectrometry (ICP-MS). The metal ion release among the solutions and the welding methods were compared. The Kruskal-Wallis and analysis of variance (ANOVA) tests were used for the group comparisons, and post hoc Dunn multiple comparison test was utilized for the two group comparisons. RESULTS: The level of metal ion release from samples of silver soldering was higher than from samples of laser welding. Furthermore, greater amounts of nickel, chrome, and iron were released from silver soldering. With regard to the mouthwash solutions, the lowest amounts of metal ions were released in CHX, and the highest amounts of metal ions were released in NaF + alcohol. SEM images were in accord with these findings. CONCLUSIONS: The laser welding should be preferred over silver soldering. CHX can be recommended for patients who have welded appliances for orthodontic reasons.

In vitro effects of two topical varnish materials and Er:YAG laser irradiation on enamel demineralization around orthodontic brackets.

The aim of this in vitro was to evaluate the effects of tricalcium phosphate (TCP) and amorphous calcium phosphate (ACP) containing varnish materials and Er:YAG laser irradiation on enamel demineralization around orthodontic brackets. Forty extracted human premolar teeth were randomly divided into four treatment groups (i.e., 10 in each group): (1) 5% NaF-ACP varnish, (2) 5% NaF-TCP varnish, (3) Er:YAG laser, and (4) control (no treatment). Er:YAG laser was operated at a wavelength of 2.94 µm and the energy output was 80 mJ per pulse; a pulse duration of 200 µsec and and a frequency of 2 Hz were used with water cooling. All samples were then put into pH cycles. Surface microhardness values and representative SEM images were assessed. Surface microhardness values were evaluated using Kruskal-Wallis and Mann-Whitney U tests. The results revealed that demineralization was significantly lower in the TCP and ACP varnish groups, whereas mean surface microhardness values of the TCP varnish were found higher than the ACP (P < 0.05). TCP and ACP varnish materials were found effective for reducing enamel demineralization around orthodontic brackets. Use of Er:YAG laser irradiation as described in this study for inhibition of demineralization was found not satisfactory.

Effects of fixed functional therapy on tongue and hyoid positions and posterior airway.

OBJECTIVE: To evaluate how therapy with a fixed functional appliance affects airway dimensions, dentoalveolar changes, and tongue and hyoid positions. MATERIALS AND METHODS: A retrospective study was carried out on 46 pre- and posttreatment lateral cephalometric radiographs of 23 post-peak Class II patients (12 girls, 11 boys) treated with a Forsus Fatigue Resistant Device (FRD) appliance. The radiographies were taken at the start and at the end of Forsus FRD appliance therapy when a Class I or overcorrected Class I canine and molar relationship was achieved. The process took an average of 5 months 13 days ± 1 month 4 days. Skeletal and dental parameters were measured using Dolphin software, and the sagittal airway area was measured by AutoCAD software. RESULTS: Analyses of the pre- and posttreatment means revealed that there was no statistically significant skeletal correction of the sagittal malocclusion; increase of lower incisor inclination, decrease of upper incisor inclination, decrease of interincisal angle, and rotation of occlusal plane all contributed to the reduction of overjet. The tongue area and intermaxillary space area increased in response to these dentoalveolar changes; however, there was no statistically significant change in the hyoid position or the oropharyngeal area between the two time points. CONCLUSIONS: The dentoalveolar changes produced by Forsus FRD appliance did not cause any significant posterior airway changes in young adult patients.

The effects of three different mouth rinses in a 4-day supragingival plaque regrowth study.

OBJECTIVE: This study compares the effects of three different mouth rinses with respect to reducing Streptococcus mutans (S. mutans) colony counts on the teeth and tongue surfaces. MATERIALS AND METHODS: In this study, comparison tests using the alcohol-free 0.1% chlorhexidine mouth rinse, alcohol-containing essential oil mouth rinse, and alcohol-free essential oil-containing mouth rinse were conducted. Patients were instructed to avoid mechanical cleaning with either a toothbrush or toothpick for 4 days. The first samples were collected from teeth surfaces and the dorsum of the tongue after a professional cleaning, and the second samples were collected after a 4-day plaque re-growth period. The supragingival plaque from the buccal surfaces of teeth #11, 14, 31, 34 as well as samples from the dorsum of the tongue, were assessed using the Dentocult(®) strips. RESULTS: The Listerine(®) and Ondrohexidine(®) groups did not show any statistically significant differences between the values of the two samples (P = 0.734, P = 0.307). The MC(®) group and the control group showed significantly higher results than the first sample values. The effectiveness of the mouth rinses on S. mutans colony counts from the teeth surfaces were higher in the Listerine(®), Ondrohexidine(®), and Mouthwash Concentrate(®) groups. The difference between the first and second samples of the S. mutans colony counts from the tongue surface was found to be statistically significant, and S. mutans colony counts were higher than the first sample (P = 0.015). CONCLUSION: Alcohol and essential oil-containing Listerine(®) mouth rinse, alcohol-free Ondrohexidine(®), alcohol-free essential oil-containing MC(®) mouth rinse had the same effect on S. mutans counts, higher than the 1% alcohol solution on teeth surface. They had the ability to maintain the S. mutans counts at the same level for 4 days in patients who did not perform any mechanical oral hygiene regimen.

The genetic basis of dental anomalies and its relation to orthodontics.

The interruption of odontogenesis by any etiological factor may result in dental anomalies. Apart from the environmental factors, the impact of genetics in dental anomalies was found to be a factor in different levels. Many authors had questioned a common genetic defect resulting in different phenotypic conditions such as absent, malformed, malposed or ectopic teeth. Because the multidisciplinary treatment of these dental anomalies such as hypodontia, impaction etc., involves orthodontic intervention, orthodontists must be aware of the etiology and possible correlative conditions with dental anomalies.

The genetic basis of facial skeletal characteristics and its relation with orthodontics.

Successful treatment of any orthodontic problem depends on an appropriate diagnosis of its etiology. It is well known that the genetics, as well as environmental factors, play an important role on the etiology of skeletal anomalies. Recent studies and advances in genetic sciences allowed the orthodontists to better understand the effects of genetics on the etiology of dentofacial characteristics and pathologies which in turn supported the effects of the genes in the development of dentofacial complex. In orthodontic practice, the genetic basis of a skeletal anomaly should also be considered during the diagnosis. Therefore orthodontic treatment plan should be chosen accordingly. However, further genetic studies are required to clearly determine all the specific genes leading to a particular skeletal variability caused by the polygenic nature of craniofacial traits. This article includes the current information on the association between orthodontics and genetics, an outline of the evidence based impact of heredity on dentofacial development as a review of the etiological factors of skeletal anomalies from the genetic point of view.

Effects of different application durations of scanning laser method on debonding strength of laminate veneers.

Porcelain laminate veneers as esthetic and minimally invasive restorations are being used as an alternative to full veneer crowns. However, the removal of porcelain veneers that have failed may be an uncomfortable and time-consuming procedure because of the high bond strength between the porcelain laminate veneers and the tooth surface. The purpose of this study was to prepare a simple and reliable method for porcelain laminate veneer debonding by using an Er:YAG laser with the scanning method and to determine the amount of lasing time required. Eighty cylindrical specimens with a thickness of 0.7 mm and a diameter of 5 mm were fabricated from Empress II ceramic material. They were cemented on the labial surface of extracted bovine mandibular incisors using Variolink II (Ivoclar Vivadent AG, Schaan, Liechtenstein) and light cured for 40 s. The specimens were randomly divided into four groups of 20. The first group was assigned as the control group and no laser application was performed. The Er:YAG laser was applied on each specimen in the other three study groups for 3, 6, and 9 s by using the scanning method. One second after the lasing, a mechanical force was applied to remove the laminate veneers by using an Instron Universal Testing machine. Results of this study exhibited statistically significant differences between the control group and the three study groups. Intergroup comparison of shear bond strengths of the three study groups showed a statistically significant difference (p = 0.0001). This study showed that all three application times of Er-YAG laser were effective for debonding ceramic laminate veneers by softening the adhesive resin.