Onur Kadioglu

Contact damage to root surfaces of premolars touching miniscrews during orthodontic treatment

INTRODUCTION Our aim in this clinical study was to examine premolar root surfaces after intentional contact with miniscrews. METHODS Ten patients (5 male, 5 female; mean age, 15.8 years; range, 13.5-23.2 years) with 2 maxillary first premolars to be extracted as part of their orthodontic treatment participated in the study. Two miniscrews were placed in each patient, and the first premolar roots were tipped into contact with the miniscrews by using tipping springs with a standardized force. Half of the experimental teeth were kept in contact with the screws for 4 weeks (mild resorption) and the other half for 8 weeks (severe resorption). In 5 patients, the screws were removed, and, in the remaining 5, the springs were removed to allow the roots to move back. The roots were allowed to recover for 4 or 8 weeks before extraction. Two premolars with accidental direct contact were used as controls. All teeth were prepared, coated, and examined with scanning electron microscopy. RESULTS In the control group, the periodontal ligament was removed and the dentin surface denuded. The experimental groups showed signs of resorption with structural surface irregularities. However, no apparent denuded dentin surfaces were seen. Although some resorption lacunae were still discernible at 8 weeks, the collagen fibers fully covered the affected areas. The immature fiber organization in the deepest crater represented the ongoing process of fiber reorganization, compared with the fully matured surface areas surrounding the crater. CONCLUSIONS The results indicate that root surfaces that touch miniscrews show swift repair and almost complete healing within a few weeks after removal of the screw or the orthodontic force. These findings are based on 10 patients only; verification in a larger study sample is needed.

Evaluation of 3 retention protocols using the American Board of Orthodontics cast and radiograph evaluation

INTRODUCTION The purpose of this study was to quantify tooth movement among different retention protocols after the orthodontic appliances were removed. METHODS A total of 90 patients were evaluated using the American Board of Orthodontics discrepancy index and the cast and radiograph evaluation at debond and the 1-year recall. These patients were equally divided into 3 retention protocols: upper Hawley/lower Hawley, upper Hawley/lower bonded, and upper Essix/lower bonded. The patients were then equally grouped by extraction or nonextraction treatment and case complexity. Paired t tests were used to compare the paired sample means. Analysis of variance tests were used to compare the means for more than 2 groups. A 2-sided 0.05 alpha level was used to define statistical significance. RESULTS The upper Hawley/lower bonded showed the greatest amount of settling, and the upper Essix/lower bonded had the least settling, but these differences were statistically insignificant. The differences between the extraction and nonextraction treatments were not significant. The group with low discrepancy index scores showed significantly more settling than did the group with high discrepancy index scores. CONCLUSIONS The cast and radiograph evaluation variables that improved overall were marginal ridges, overjet, occlusal contacts, interproximal contacts, root angulation, and total cast and radiograph score. The cast and radiograph evaluation variables that worsened were alignment/rotation, buccolingual inclination, and occlusal relationship. Extraction or nonextraction treatment led to no real difference in settling. The discrepancy index, or initial case complexity, was the greatest factor in determining the improvement of occlusion or settling during the retention phase.

Postsurgical volumetric airway changes in 2-jaw orthognathic surgery patients

INTRODUCTION Findings from early cephalometric studies on airway changes after 2-jaw orthognathic surgery have been challenged because the previous anteroposterior interpretation of airway changes can now be evaluated in 3 dimensions. The aims of this study were to use cone-beam computed tomography to quantify the nasopharynx, oropharynx, and total airway volume changes associated with skeletal movements of the maxilla and mandible in a sample of patients undergoing 2-jaw orthognathic surgery for correction of skeletal malocclusion. METHODS Skeletal movements and airway volumes of 71 postpubertal patients (31 male, 40 female; mean age, 18.8 years) were measured. They were divided into 2 groups based on ANB angle, overjet, and occlusion (Class II: ANB, >2°; overjet, >1 mm; total, 35 subjects; and Class III: ANB, <1°; overjet, <1 mm; total, 36 subjects). Presurgical and postsurgical measurements were collected for horizontal, vertical, and transverse movements of the maxilla and the mandible, along with changes in the nasopharynx, oropharynx, and total airways. Associations between the directional movements of skeletal structures and the regional changes in airway volume were quantified. Changes in the most constricted area were also noted. RESULTS Horizontal movements of D-point were significantly associated with increases in both total airway (403.6 ± 138.6 mm(3); P <0.01) and oropharynx (383.9 ± 127.9 mm(3); P <0.01) volumes. Vertical movements of the posterior nasal spine were significantly associated with decreases in total airway volume (-459.2 ± 219.9 mm(3); P = 0.04) and oropharynx volume (-639.7 ± 195.3 mm(3); P <0.01), increases in nasopharynx (187.2 ± 47.1 mm(3); P <0.01) volume, and decreases in the most constricted area (-10.63 ± 3.69 mm(2); P <0.01). In the Class III patients only, the vertical movement of D-point was significantly associated with decreases in both total airway (-724.0 ± 284.4 mm(3); P = 0.02) and oropharynx (-648.2 ± 270.4 mm(3); P = 0.02) volumes. A similar negative association was observed for the most constricted area for the vertical movement of D-point (-15.45 ± 4.91 mm(2); P <0.01). CONCLUSIONS Optimal control of airway volume is through management of the mandible in the horizontal direction and the vertical movement of the posterior maxilla for all patients. The surgeon and the orthodontist should optimally plan these movements to control gains or losses in airway volume as a result of orthognathic surgery.

Digital tooth-based superimposition method for assessment of alveolar bone levels on cone-beam computed tomography images

INTRODUCTION Cone-beam computed tomography images have been previously used for evaluation of alveolar bone levels around teeth before, during, and after orthodontic treatment. Protocols described in the literature have been vague, have used unstable landmarks, or have required several software programs, file conversions, or hand tracings, among other factors that could compromise the precision of the measurements. The purposes of this article are to describe a totally digital tooth-based superimposition method for the quantitative assessment of alveolar bone levels and to evaluate its reliability. METHODS Ultra cone-beam computed tomography images (0.1-mm reconstruction) from 10 subjects were obtained from the data pool of the University of Oklahoma; 80 premolars were measured twice by the same examiner and a third time by a second examiner to determine alveolar bone heights and thicknesses before and more than 6 months after orthodontic treatment using OsiriX (version 3.5.1; Pixeo, Geneva, Switzerland). Intraexaminer and interexaminer reliabilities were evaluated, and Dahlbergs formula was used to calculate the error of the measurements. RESULTS Cross-sectional and longitudinal evaluations of alveolar bone levels were possible using a digital tooth-based superimposition method. The mean differences for buccal alveolar crest heights and thicknesses were below 0.10 mm for the same examiner and below 0.17 mm for all examiners. The ranges of errors for any measurement were between 0.02 and 0.23 mm for intraexaminer errors, and between 0.06 and 0.29 mm for interexaminer errors. CONCLUSIONS This protocol can be used for cross-sectional or longitudinal assessment of alveolar bone levels with low interexaminer and intraexaminer errors, and it eliminates the use of less reliable or less stable landmarks and the need for multiple software programs and image printouts. Standardization of the methods for bone assessment in orthodontics is necessary; this method could be the answer to this need.

Prostaglandin E2 levels in gingival crevicular fluid during tooth- and bone-borne expansion

The purpose of this study was to compare Prostaglandin E(2) (PGE(2)) levels in gingival crevicular fluid (GCF) of young adults with maxillary constriction during tooth- and bone-borne expansion. Thirty patients, 15 females and 15 males, with a mean age of 17.3 +/- 2.8 years were divided into three groups. Group I consisted of 10 patients, five females and five males, treated by transpalatal distraction (TPD) as a bone-borne device, group II 10 patients, five females and five males, with a Hyrax appliance as a tooth-borne device, and a control group of 10 patients, five females and five males, without any expansion appliances. GCF samples were collected with filter paper strips at six observation periods in order to evaluate the effect of heavy orthopaedic forces in both groups. In group II, the samples were additionally collected at two pre-treatment time points in order to evaluate the effect of the forces generated by the separators. An automated enzyme immunoassay was used to measure PGE(2) in the GCF. The differences within the groups were evaluated with a pairwise t-test and the differences between the groups were determined by the Mann-Whitney U-test. The mean PGE(2) level was significantly elevated on day 4 after placement of the separators in group II (P < 0.05). The PGE(2) values in group II were significantly different to those in group I and the controls at all observation periods. Lower PGE(2) levels were observed in group I compared with group II and the controls. Expansion using the TPD method could potentially enhance the prognosis of the teeth by inducing more skeletal dental changes when compared with the Hyrax appliance.

Flexural properties of rectangular nickel-titanium orthodontic wires when used as ribbon archwires.

OBJECTIVE: To compare the flexural properties of rectangular nickel-titanium (Ni-Ti) orthodontic wires in occlusoapical and faciolingual orientations using a standardized test method. MATERIALS AND METHODS: Twenty-two rectangular Ni-Ti wire groups were tested in occlusoapical (ribbon) orientation: eight conventional Ni-Ti products, five superelastic Ni-Ti products, and nine thermal Ni-Ti products (n = 10 per group). Six products of thermal Ni-Ti wire were tested in faciolingual (edgewise) orientation. A three-point bending test was performed to measure deactivation force at 3.0-, 2.0-, 1.0-, and 0.5-mm deflections of each rectangular wire at 37.0 ± 0.5°C. Analysis of variance and post hoc Student-Newman-Keuls tests were used to compare the mean values of the different groups (α = .05). RESULTS: The ranges of deactivation forces varied greatly with different kinds, sizes, products, and deflections of Ni-Ti wires. One product of conventional and superelastic Ni-Ti wires had steeper force-deflection curves. Four products had similarly shaped flat force-deflection curves, whereas the sixth product had a moderately steep force-deflection curve. Thermal Ni-Ti wires had smaller deactivation forces ranging from 0.773 N (78.8 g) to 2.475 N (252.4 g) between deflections of 1.0 and 0.5 mm, whereas wider ranges of force from 3.371 N (343.7 g) to 9.343 N (952.7 g) were predominantly found among conventional Ni-Ti wires between deflections of 3.0 and 2.0 mm. CONCLUSIONS: Clinicians should critically select archwires for use in the occlusoapical orientation not only based on Ni-Ti wire type, size (0.022 × 0.016-in or 0.025 × 0.017-in), and product but also with deactivation deflections from 0.5 and 1.0 mm to obtain light forces in the occlusoapical orientation.