Gholamreza Danesh

Bending properties of rotary nickel-titanium instruments

OBJECTIVE We sought to compare the bending properties of different rotary nickel-titanium instruments and to investigate the correlation between their bending moments and their cross-sectional surface areas. STUDY DESIGN Resistance to bending was determined according to International Standards Organization publication 3630-1. The sample size was 10 files for each type, taper, and size. The cross-sectional surface area of all instruments was determined by using scanning electron microscope photographs of the cross section. The images were scanned and the area was calculated by using special software. Data were analyzed by using analysis of variance and the Student t test and the Newman-Keuls test for all pairwise comparisons. The strength of the correlation between the bending moment and the cross-sectional area was determined by computing the Pearson product moment correlation. RESULTS Bending moments were significantly lower for ProFile and RaCe files than for all other files (P <.05). K3 files were significantly less flexible than all other instruments (P <.05). The correlation between stiffness and cross-sectional area was highly significant (r = 0.928; P <.0001). CONCLUSION Nickel-titanium files with tapers greater than.04 should not be used for apical enlargement of curved canals because these files are considerably stiffer than are those with.02 or.04 tapers.

Interdisciplinary Study of Orthopedic and Orthodontic Findings in Pre-school Infants

Abstract.Background and Aim:The assessment of correlations between orthopedic and orthodontic data based on interdisciplinary studies is of scientific and practical interest in the differentiation of preventive diagnostic and therapeutic fields between orthodontics and orthopedics. In the published literature there are various studies analyzing the correlations between specific Angle classes and orthopedic parameters. Results of these studies indicate a potential correlation between scoliosis and Class II malocclusion as well as between weak body posture and Class II malocclusion. The aim of the present interdisciplinary study was to examine correlations between orthodontic and orthopedic findings in preschool infants and to evaluate them with respect to preventive recommendations.Patients and Method:59 pre-school infants (29 boys, 30 girls) aged 3.5–6.8 years (mean: 5.0 years) were enrolled in this study. A standardized orthodontic and orthopedic examination protocol was used.Results:The orthodontic examination showed Angle class distributions comparable with those in non-selected groups (Class I: 63%, Class II: 32%, Class III: 5%). The orthopedic examination revealed pathologic findings in 52% of the subjects, with statistically significant correlations between scoliosis and Class II malocclusion (p = 0.033) and between weak body posture and Class II malocclusion (p = 0.028).Conclusion:It can be concluded from the results that the orthodontic finding of Angle Class II in pre-school infants should induce prophylactic screening. The orthodontist could then not only initiate early orthodontic treatment to prevent incisor trauma in patients with extreme overjet, but could also take account of potential orthopedic malformations on a preventive interdisciplinary basis in pre-school infants with Class II malocclusions.Zusammenfassung.Hintergrund und Ziel:Die Bewertung von Beziehungen zwischen orthopädischen und kieferorthopädischen Befunden auf der Basis von interdisziplinären Studien ist von wissenschaftlichem und praktischem Interesse für die Differenzierung von präventiven gemeinsamen Diagnostik- und Therapiebereichen zwischen Kieferorthopädie und Orthopädie. Im bekannten Schrifttum finden sich mehrere Studien, welche Zusammenhänge zwischen bestimmten Angle-Klassen und orthopädischen Parametern evaluieren. Ergebnisse dieser Studien deuten auf eine mögliche Beziehung von Skoliosen und hypotoner Körperhaltung mit Angle-Klasse-II-Dysgnathien hin. Prospektives Ziel der vorliegenden interdisziplinären Studie war es, Beziehungen zwischen orthopädischen und kieferorthopädischen Befunden bei Vorschulkindern zu untersuchen und hinsichtlich präventiver Empfehlungen zu evaluieren.Patienten und Methode:59 Vorschulkinder im Alter von 3,5 bis 6,8 Jahren wurden in diese Studie einbezogen. 29 Patienten waren männlich, 30 weiblich. Es erfolgten eine standardisierte klinische kieferorthopädische und orthopädische Untersuchung.Ergebnisse:Bei der kieferorthopädischen Untersuchung zeigte sich eine der Verteilung in unselektierten Gruppen entsprechende Angle-Klasse-Häufigkeit (Angle-Klasse I 63%, Angle-Klasse II 32% und Angle-Klasse III 5%). Die orthopädische Untersuchung ergab bei 52% der Probanden Auffälligkeiten mit den folgenden statistisch signifikanten Korrelationen: Angle-Klasse II und Skoliose (p = 0,033) sowie Angle-Klasse II und hypotone Körperhaltung (p = 0,028).Schlussfolgerung:Aus den Ergebnissen kann geschlussfolgert werden, dass bei Kindergartenkindern der kieferorthopädische Befund der Angle-Klasse II eine mögliche prophylaktische Screeninguntersuchung auslösen sollte. Der Kieferorthopäde kann somit nicht nur bei extremer Frontzahnstufe eine kieferorthopädische Frühbehandlung zur Frontzahntraumaprophylaxe initiieren, sondern auch bei Angle-Klasse-II-Dysgnathien aller Schweregraduierungen interdisziplinär präventiv mögliche orthopädische Fehlentwicklungen berücksichtigen.

Relationship between Thoracic, Lordotic, and Pelvic Inclination and Craniofacial Morphology in Adults

OBJECTIVE To analyze the correlation ratios between the spinal posture (thoracic, lordotic, and pelvic inclination) and the craniofacial morphology. MATERIALS AND METHODS The sample consisted of 53 healthy adults (32 women, 21 men; mean age 24.6 years). Six angular skeletal measurements (facial axis, mandibular plane angle, inner gonial angle, lower facial height, facial depth, and maxilla position) were determined based on the analysis of lateral head cephalographs. Rasterstereography was used for a precise reconstruction of the back sagittal profile. From the profile parameters, the upper thoracic inclination, the thoracic angle, the lordotic angle, and the pelvic inclination were determined. The correlations to the craniofacial morphology were calculated by means of the Pearson and Mann-Whitney U-test. RESULTS Significant correlations could be obtained with respect to the facial axis and the lordotic angle, the facial axis and the pelvic inclination, the inner gonial angle and the lordotic angle, the inner gonial angle and the pelvic inclination, the mandibular plane angle and the lordotic angle, the mandibular plane angle and the pelvic inclination, as well as the facial depth and the pelvic inclination. CONCLUSIONS In the case of postural disorders of the back shape, an interdisciplinary treatment approach seems to be of clinical value. Further prospective studies are necessary to prove how changes in craniofacial parameters can affect the postural balance of an individual.

Sagittal Spinal Posture in Relation to Craniofacial Morphology

OBJECTIVE The aim of this study is to determine correlations between the parameters of body posture in the sagittal profile and sagittal jaw position by obtaining objective and valid three-dimensional measurements of the dorsal profile by means of rasterstereography. MATERIALS AND METHODS Fifty-three adults with Class II or III malocclusions were examined, and six angular parameters were determined. For the sagittal analysis of body posture, the Fleche Cervicale and Lombaire as well as trunk inclination were evaluated. RESULTS Statistically significant correlations (P < .05) were found between Facial Axis and Fleche Cervicale, Mandibular Plane angle and Fleche Cervicale, and Facial Depth and the Fleche Cervicale. CONCLUSIONS It can be concluded that the mandible seems to have a greater effect on body posture than other craniofacial parameters. As a clinical result of this study, patients with severe malocclusions should be examined interdisciplinarily before orthognathic surgery is performed to minimize postural influence on the altered jaw relationship after surgery.

Trunk Inclination, Pelvic Tilt and Pelvic Rotation in Relation to the Craniofacial Morphology in Adults

OBJECTIVE To relate the differences in the posture of patients with different craniofacial morphologies. SUBJECTS AND METHODS Fifty-three adult patients with Class II and III malformations were examined by cephalometric analysis and rasterstereography. The facial depth, maxillary position, mandibular plane angle, inner gonial angle, facial axis, and lower facial height were evaluated and classified into a basal distal-mesial group and a horizontal-vertical group by means of threshold parameters. Analyzing the results of the rasterstereography, the spines lateral perpendicular deviation, the pelvic tilt, and the pelvic rotation were calculated by means of mathematical algorithms on the basis of the three-dimensional spine profile. To determine the statistically significant correlations between the studied parameters, the t-test was applied in groups with a normal distribution, and the Mann-Whitney U-test was used in the cases of abnormally distributed variables (significance level P < .05). RESULTS Statistically significant differences (P < .05) in pelvic torsion were documented with respect to the facial axis and facial depth. Moreover, the differences (P < .05) between patients with a skeletal horizontal-vertical facial axis and patients with a basal distal-mesial position for the facial depth could be determined for the pelvic torsion. CONCLUSIONS As a clinical consequence of the results, an extension of the interdisciplinary concepts within the sense of an orthopedic examination can be considered for patients undergoing a combined orthodontic-operative therapy.

A Fused Maxillary Central Incisor with Dens Evaginatus as a Talon Cusp

This report presents a rare case of concurrence of dens evaginatus and dental fusion affecting the maxillary right upper central incisor of a 9-year-old male patient. An association of dens evaginatus and dental fusion within the same tooth is rare. In this case, an orthopantomogram, a lateral cephalogram, intraoral radiographs, and a magnetic resonance tomogram were made to obtain a proper diagnosis and to confirm the exact path of the root canals. Because of a forced bite, an orthodontic treatment involving cusp reduction was initiated. During the cusp reduction, no traumatic intraoperative exposure of pulp tissue occurred, and no endodontic or surgical treatment procedures were necessary. After a multibracket treatment, a harmonious integration of the tooth in the upper dental arch was achieved.

Analysis of Condylar Differences in Functional Unilateral Posterior Crossbite during Early Treatment – a Randomized Clinical Study

Objective:The analysis of potential discrepancies in condyle position among different occlusal relations (centric relation and maximum intercuspidation) is a key diagnostic component when treating children with unilateral posterior crossbite. Due to strict requirements imposed by ethics committees, and new regulations regarding the use of X-rays, radiological examinations (axial cephalometric radiographs or postero-anterior cephalometric radiographs) are not feasible. Thus the aim of this study was to apply an alternative procedure for the assessment of condylar deviations.Probands and Methods:We employed ARCUS®digma, a measuring system based on ultrasound technology, to record condylar differences occurring in 65 children (6.9 ± 2.0 years of age) with functional unilateral posterior crossbite in late deciduous and early mixed dentition. After randomization, 31 patients underwent early orthodontic treatment (bonded palatal expansion appliance and U-bow activator), whereas 34 patients remained untreated. Examinations were carried out at the beginning (T1) and after 12 months of treatment (T2). A three-dimensional (3D) assessment of deviations between maximum intercuspidation and centric position was carried out. Statistical analysis was performed using the SPSS® 12.0 software program.Results:Initially, the electronic position analysis revealed no significant differences between the control and therapy groups. A mean condylar deviation of > 2 mm was noted at T1 in the sagittal, frontal and transversal planes for crossbite and the noncrossbite sides. This difference was reduced in the therapy group, a finding that proved statistically highly significant (p < 0.001). We also observed a highly significant (p < 0.001) difference between the control and therapy groups at T2.Conclusion:The Münster concept for early treatment of functional unilateral posterior crossbites in late deciduous and early mixed dentition significantly improved the treated patients’ occlusion in comparison to a randomized control group, which exhibited no spontaneous self-healing tendencies.ZusammenfassungZiel:Die Analyse möglicher Abweichungen der Gelenkposition zwischen differenten okklusalen Relationen (zentrikgeführte und maximale Interkuspidation) erscheint als wichtige diagnostische Komponente bei Kindern mit funktionellem unilateralem posteriorem Kreuzbiss. Durch die strengen Vorgaben der Ethikkomission und auf Basis der neuen Röntgenverordnung sind keine radiologischen Maßnahmen (axiale Schädelaufnahme oder Fernröntgenfrontalaufnahme) möglich. Daher war es Ziel dieser Studie, eine alternative Methode anzuwenden, mit der Abweichungen im kondylären Bereich ermittelt werden konnten.Material und Methodik:Das gelenkfern arbeitende ultraschallbasierte Messsystem ARCUS®digma diente bei 65 Kindern (6,9 ± 2,0 Jahre) mit funktionellem unilateralem posteriorem Kreuzbiss in der späten Milch- und frühen Wechselgebissperiode zur Registrierung von kondylären Differenzen. Nach der Randomisierung erhielten 31 der Patienten eine kieferorthopädische Frühbehandlung (Kunststoffkappenschiene und U-Bügel-Aktivatortherapie); bei 34 Patienten erfolgte keine Therapie. Die Untersuchung wurde zu Beginn (T1) und nach 12 Monaten (T2) durchgeführt. Die Analyse der Abweichung zwischen maximaler Interkuspidation und zentrischer Position erfolgte für die drei Raumebenen. Die statistische Analyse erfolgte mit SPSS®12.0.Ergebnisse:Zu Beginn der Untersuchung ergab die elektronische Positionsanalyse der Kiefergelenke keine signifikanten Unterschiede zwischen der Kontroll- und Therapiegruppe. Zu T1 konnte in der Sagittal-, Frontal- und Transversalebene für die Kreuzbissund die Nichtkreuzbissseite eine mittlere kondyläre Differenz > 2 mm ermittelt werden. Für die Therapiegruppe zeigte sich zwischen T1 und T2 eine statistisch höchstsignifikante (p < 0,001) Reduzierung dieser Differenz. Zu T2 konnte ein statistisch höchstsignifikanter (p < 0,001) Unterschied zwischen Kontroll- und Therapiegruppe ermittelt werden.Schlussfolgerung:Die kieferorthopädische Behandlung des funktionellen unilateralen posterioren Kreuzbisses in der späten Milch- und frühen Wechselgebissperiode nach dem Münsteraner Frühbehandlungskonzept liefert für die beobachteten Probanden signifikante Verbesserungen hinsichtlich funktioneller Parameter des Kiefergelenks gegenüber einer randomisiert etablierten Kontrollgruppe, bei der keine Selbstausheilungstendenz festgestellt werden konnte.

Early treatment of posterior crossbite - a randomised clinical trial

BackgroundThe aim of this randomised clinical trial was to assess the effect of early orthodontic treatment in contrast to normal growth effects for functional unilateral posterior crossbite in the late deciduous and early mixed dentition by means of three-dimensional digital model analysis.MethodsThis randomised clinical trial was assessed to analyse the orthodontic treatment effects for patients with functional unilateral posterior crossbite in the late deciduous and early mixed dentition using a two-step procedure: initial maxillary expansion followed by a U-bow activator therapy. In the treatment group 31 patients and in the control group 35 patients with a mean age of 7.3 years (SD 2.1) were monitored. The time between the initial assessment (T1) and the follow-up (T2) was one year. The orthodontic analysis was done by a three-dimensional digital model analysis. Using the ‘Digimodel’ software, the orthodontic measurements in the maxilla and mandible and for the midline deviation, the overjet and overbite were recorded.ResultsSignificant differences between the control and the therapy group at T2 were detected for the anterior, median and posterior transversal dimensions of the maxilla, the palatal depth, the palatal base arch length, the maxillary arch length and inclination, the midline deviation, the overjet and the overbite.ConclusionsOrthodontic treatment of a functional unilateral posterior crossbite with a bonded maxillary expansion device followed by U-bow activator therapy in the late deciduous and early mixed dentition is an effective therapeutic method, as evidenced by the results of this RCT. It leads to three-dimensional therapeutically induced maxillary growth effects. Dental occlusion is significantly improved, and the prognosis for normal craniofacial growth is enhanced.Trial registrationRegistration trial DRKS00003497 on DRKS

Elution characteristics of residual monomers in different light- and auto-curing resins.

The aim of this in vitro study was to assess different auto-curing resins based on methylmethacrylate (MMA) and new light-curing resins based on urethane dimethacrylate (UDMA) regarding the residual monomers remaining in the resin and their elution over time. Specimens from three auto-curing and three light-curing resins were produced following the manufacturers instructions. The concentration of residual MMA and UDMA monomers present in the resins as well as the quantity of the residual monomers released into artificial saliva solution after immersion times of 1, 3, and 7 days were analyzed by high-performance liquid chromatography (HPLC). Data were statistically analyzed using ANOVA and the post hoc Student-Newman-Keuls test. The highest and lowest amounts of residual monomers were found in the group of light-curing resins (p<0.05). The light-curing resins Triad Trans Sheet (0.06 wt%) and Primosplint (0.06 wt%) released over the entire immersion time of 7 days the smallest (p<0.05) quantity of UDMA. These two light-curing resins based on UDMA exhibited lower elution of residual monomers than auto-curing resins (MMA). The elution characteristics of the residual monomers do not seem to correlate with the residual monomer concentration in resins. These observations demonstrate that the quantitative determination of residual monomers alone - as required by the ISO specification 20795-1 - does not seem to be sufficient for an assessment of the biological properties of different resins. Instead, the evaluation of elution characteristics appears to be of higher clinical relevance.

Facial landmark localization by curvature maps and profile analysis

IntroductionThree-dimensional landmarks of the face are important for orthodontic examination, harmony assessment and treatment planning. Currently, facial landmarks are often measured by orthodontists via direct observation and manual soft tissue image analysis. This study wants to evaluate and present an objective method for measuring selected facial landmarks based on an analysis of curvature maps and of sagittal profile obtained by a laser-scanning method.MethodsThe faces of 15 people were scanned in 3D by means of the laser scanner FastSCAN™. It allowed the recording of a curvature map of the face in under a minute, which depicted the distribution of Gaussian and mean curvatures. The median-sagittal profile line of the face was localized in this map, and a mathematical analysis comprising its first and second derivatives was performed. Anatomical landmarks were identified and facial measurements performed. To assess validity the obtained data were compared with manual measurements by orthodontists by means of Lin’s concordance correlation CCC coefficient and reliability was determined by consecutive measurements.ResultsFacial landmarks, such as the soft tissue glabella and nasal tip, could be easily and accurately identified and located. Lin’s CCC showed substantial agreement between digital and manual measurements for 4 of the 7 distances evaluated. Larger discrepancies were due to inadequate image quality and scanning errors. Reliability of consecutive measurements by the same operator was excellent.ConclusionsIn our pilot study the three-dimensional laser-scanning method FastSCAN™ allowed a reliable and accurate identification of anatomical landmarks of the face. The obtained distances between certain landmarks, such as the intercanthal distance, were largely consistent with those from manual measurements. Due to its easy and rapid implementation, the method facilitates facial analysis and could be a clinically valid alternative to manual measurements, when remaining problems in scanning accuracy can be resolved.