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ABSTRACT: To conduct a pilot study to investigate the potentiality to determine the midpalatal sutural width radiographically with a flat-panel volume computed tomography (fpVCT) in a porcine model.
Bone samples from the midpalatal suture of five young (16 weeks) and five old (200 weeks) sus scrofa domestica were gathered. The midpalatal suture width was measured via fpVCT and compared to respective histological preparations. Results with P < .05 were considered significant.
The data obtained by fpVCT and by histomorphometric analysis reveal a highly significant age dependency of the measured suture width (both P < .0001), with lower suture width values in older subjects compared to the younger group. The averaged suture widths measured in the fpVCT images shows a distinctively higher mean compared to the histomorphometric data with high statistical significance (P < .0001). The evaluated difference between both methods was almost constant.
fpVCT is a powerful tool for determining midpalatal sutural width.
The Angle Orthodontist 08/2011; 82(1):145-50. · 1.21 Impact Factor
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ABSTRACT: To determine the forces and moments delivered to a maxillary central incisor during rotation with aligners when a simulated occlusal force generated during swallowing acts on the appliance.
Five identical appliances were manufactured from four different starting materials (Erkodur 0.8 mm and 1.0 mm; Biolon 0.75 mm and 1.0 mm). An upper central incisor fixed in a measuring device was rotated around its central axis in 0.5-degree steps up to ±10 degrees with the appliance fixed in place. An occlusal force of 30 N generated during swallowing was simulated with a weight positioned on the appliance. For statistical analysis, the moments Tz (rotation) and forces Fz (intrusion) at a deflection of ±0.34 mm to the incisor edge (±5 degrees rotation) were tested. Means and standard deviations for Tz and median and 25% and 75% quartiles for Fz were calculated. An analysis of variance was performed.
The simulated occlusal force increased the measured intrusive force Fz (maximum with a weight, -3.7 N [-3.7, -2.4]; minimum without a weight, -1.3 N [-1.4, -1.1]) and the rotary moment Tz (maximum with a weight, -50.8 Nmm [±0.8]; minimum without a weight, 18.2 Nmm [±0.9]) significantly in all cases (P < .01). This was found for all materials measured and for both directions of rotation.
During rotation with aligners, a simulated occlusal force increases the intrusive force and the rotary moment. The biological adverse side effects of these phenomena remain unclear, especially in patients with periods of bruxism.
The Angle Orthodontist 05/2011; 81(6):1057-63. · 1.21 Impact Factor
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ABSTRACT: The aim of the study was to establish whether juveniles with a Class II malocclusion change the neuromuscular control of mandibular movements during the course of orthodontic treatment with removable functional appliances (RFAs). Neuromuscular control can be indirectly evaluated by recording cyclic planar mandibular movements which were freely carried out by the patients (28 girls, 14 boys, aged 11.1 ± 1.1 years at the start of treatment) and measured with an ultrasonic device before, during, and after Class II functional appliance therapy, with either an activator or a bite jumping plate. The cyclic movements represented simultaneous rotations of the mandible around a maxillary and mandibular fixed axis (MFHA) and could be characterized by μ(α)-diagrams (μ = swing angle of MFHA, α = mouth opening angle) and path length (L) of the MFHA. The μ(α)-diagrams clearly divided into four parts: movement representing protrusion, mouth opening, and two parts of backward closing as known from Posselt diagrams. Parameters from the Posselt and μ(α)-diagrams were checked by one-factor analysis of variance on a 5 per cent significance level for group dependency. For one-third of the patients investigated, no significant changes were seen in any parameter pre- or post-therapy. However, patients showing an initially large mouth opening capacity or a very short condylar path changed their neuromuscular control to that of Class I subjects. Analysis of μ(α)-diagrams provides the possibility of assessing changes in the neuromuscular control of the mandible during Class II treatment.
The European Journal of Orthodontics 01/2011; 33(6):628-35. · 0.89 Impact Factor
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ABSTRACT: The forces delivered by aligners during torquing have still not been investigated. The purpose of this study was to measure the forces delivered to an upper central incisor during torquing with three different materials of the same thickness, and to describe the biomechanical principles of torquing with aligners. Five identical appliances were manufactured from each of three materials, all with a thickness of 1.0 mm (Ideal Clear®, Erkodur®, and Biolon®). An upper central incisor, as part of the measuring device, was torqued in defined steps in the vestibular and palatal directions with the respective appliance in place. For statistical analysis, the resulting forces, Fx (forces acting in the palatal and facial directions) and Fz (intrusive force as a side-effect) at a displacement of ±0.15 and ±0.8 mm from the tooth at the gingival margin were calculated. The mean Fx forces for ±0.15 mm displacement ranged from -1.89 N [standard deviation (SD) 0.48] to 0.11 N (SD 0.1). The mean Fz forces were between -0.97 N (SD 0.57) and -0.07 N (SD 0.22). The highest intrusive forces were measured during palatal displacement of the measuring tooth. An influence of direction of displacement on the levels of force was observed, especially for Fz at the greater displacement of ±0.8 mm. In relation to the intended amount of root movement during torquing, aligners tend to 'lift up' and therefore no effective force couple can be established for further root control. The force delivery properties are also influenced by the material used and the shape of the tooth.
The European Journal of Orthodontics 05/2010; 32(6):607-13. · 0.89 Impact Factor
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ABSTRACT: To determine the forces and moments delivered to a maxillary central incisor during rotation by three different thermoplastic appliances with identical thickness.
Five identical appliances were manufactured from each of three materials (Ideal Clear 1.0 mm, Erkodur 1.0 mm, Biolon 1.0 mm). An upper central incisor fixed in a measuring device was rotated around its central axis in 0.5-degree steps to +/-2.5 degrees, +/-5 degrees, and +/-7.5 degrees (equivalent to an activation of +/-0.17 mm, +/-0.34 mm, and +/-0.51 mm of the incisor edge) in the clockwise and anticlockwise directions with the respective appliance fixed in place. For statistical analysis, the moments Tz (rotation) and forces Fz (intrusion) were tested. Means and standard deviations for Tz and median and 25% and 75% quantiles for Fz were calculated. An analysis of variance (ANOVA) was performed.
The minimal moment was determined at a rotation of -0.17 mm (-7.3 Nmm, +/-0.8), and the maximal moment at a deflection of -0.51 mm (-71.8 Nmm. +/-2.5) was recorded. The minimal value for Fz was measured at an activation of -0.17 mm (0.0 N), and the highest intrusive forces were evaluated for a rotation of -0.51 mm (-5.8 N). The particular material sometimes had a significant (P < .05) influence on the forces delivered and the moments.
During rotation with aligners, an intrusive force can also be observed. The direction of rotation, and the materials used all exert an influence on the force delivery properties of the appliance.
The Angle Orthodontist 03/2010; 80(2):239-46. · 1.21 Impact Factor
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ABSTRACT: Nonsyndromic orofacial clefts might affect family functioning and probably reduce the quality of life in school-age children and their parents. One hundred seventy consecutive children with orofacial clefts between 8 and 12 years and their families were asked to answer the Impact on Family Scale and KINDL. The results were compared with the quality of life in an age- and sex-matched group of unaffected schoolchildren. One hundred thirty-two families participated in this study. Family functioning was found superior in families with children with cleft lip than in families with children with cleft palate only or cleft lip and palate. Sex had no significant influence on family functioning. The quality of life in schoolchildren with orofacial clefts was found superior to the control group. Reductions were observed in children with cleft lip and palate in the dimensions "family" and "friends," indicating problems in the social field. Boys with orofacial clefts experienced a lower quality of life than girls. Children with cleft lip and palate and cleft palate only experienced a lower quality of life than children with cleft lip. Even years after successful cleft reconstruction, coping and mastering the diagnosis of orofacial cleft is a relevant concern for affected families. Several limitations of the quality of life in schoolchildren were identified, mostly affecting their social role.
The Journal of craniofacial surgery 10/2009; 20(6):2061-6. · 0.81 Impact Factor
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ABSTRACT: The aim of the study was to quantify the forces delivered by thermoplastic appliances made of 2 materials with 2 thicknesses to a maxillary central incisor during tipping.
Two materials were tested, each in 2 thicknesses: Erkodur (Erkodent Erich Kopp GmbH, Pfalzgrafenweiler, Germany) 1.0 and 0.8 mm, and Biolon (Dreve Dentamid GmbH, Unna, Germany), 1.0 and 0.75 mm. For each material, 5 appliances were produced. To measure the forces applied, an isolated measuring tooth, part of a standardized resin model, was deflected in 0.05 degrees steps from 0 degrees to 0.42 degrees in the vestibular and palatine directions, after placing the respective appliance on the model. For statistical analysis, the force components Fx/tipping and Fz/intrusion at a displacement of +/- 0.151 mm from the incisor edge were selected. Means and standard deviations were calculated. The Wilcoxon 2-sample test for group pairings was used.
The norms for the mean Fx forces ranged from 1.62 (SD, 0.41) to 5.35 N (SD, 0.63). The mean Fz forces were between 0.07 (SD, 0.13) and -2.47 N (SD, 0.34). The highest intrusive forces were measured during vestibular displacement of the measuring tooth. The forces delivered by the thick appliances were overall significantly higher (P <0.0001) than those of the thin materials. The forces delivered by the Biolon appliances were generally significantly higher (P <0.0001) than those for the Erkodur materials.
The forces applied were mostly too high when compared with those stated in the literature as ideal. In addition to thickness, the thermoforming process influences the magnitude of the force delivered by a thermoformed appliance.
American journal of orthodontics and dentofacial orthopedics: official publication of the American Association of Orthodontists, its constituent societies, and the American Board of Orthodontics 08/2009; 136(1):12.e1-7; discussion 12-3. · 1.33 Impact Factor
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ABSTRACT: The force properties of thermoformed appliances have not been systematically investigated. Therefore, the aim of the present study was to quantify the forces delivered by thermoplastic appliances manufactured from three different materials, with the same thickness, on a central upper incisor, during tipping. Five identical appliances were manufactured from three different materials all with a thickness of 1.0 mm (Ideal Clear, Erkodur, and Biolon). For measuring the forces, an isolated measuring tooth, as part of a standardized resin model incorporated in a newly developed measuring device, was tipped in nine 2.7 arc minute (0.04629 degree) steps, from 0 to 0.416 degrees in the vestibular and palatal directions around a rotational axis through the virtual apex, after positioning an appliance on the model. For statistical analysis, the force components Fx/tipping and Fz/intrusion at a displacement of +/-0.151 mm from the incisor edge were determined. Means and standard deviations (SDs) were calculated. The Kruskal-Wallis test for overall effects and the Wilcoxon two-sample test for individual group pairings were used (P < 0.05 significance level). The mean Fx forces ranged from -2.82 N (SD 0.62) to 5.42 N (SD 0.56). The mean Fz forces were between -0.14 N (SD 0.52) and -2.3 N (SD 0.43). The highest intrusive forces were measured during vestibular displacement of the measuring tooth. The forces delivered by the Biolon appliance were found to be much greater (P < 0.01) than those of the other materials. The forces delivered by the materials investigated were mostly higher than those stated in the literature.
The European Journal of Orthodontics 07/2009; 31(6):625-31. · 0.89 Impact Factor
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ABSTRACT: An investigation was conducted to compare the image quality of prototype flat-panel volume computed tomography (fpVCT) and multislice computed tomography (MSCT) of suture structures.
Bone samples were taken from the midpalatal suture of 5 young (16 weeks) and 5 old (200 weeks) Sus scrofa domestica and fixed in formalin solution. An fpVCT prototype and an MSCT were used to obtain images of the specimens. The facial reformations were assessed by 4 observers using a 1 (excellent) to 5 (poor) rating scale for the weighted criteria visualization of the suture structure. A linear mixed model was used for statistical analysis. Results with P < .05 were considered to be statistically significant.
The visualization of the suture of young specimens was significantly better than that of older animals (P < .001). The visualization of the suture with fpVCT was significantly better than that with MSCT (P < .001).
Compared with MSCT, fpVCT produces superior results in the visualization of the midpalatal suture in a Sus scrofa domestica model.
Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 05/2009; 108(3):443-9. · 1.50 Impact Factor
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ABSTRACT: The objective of this study consisted in determining the variability of the ANB angle in relation to the position of the A- and B-points in the sagittal vertical plane.
Using a theoretical model, we varied the position of the cephalometric points A and B in the sagittal vertical plane while its sagittal relationship was kept constant (Wits value = 0 mm). For this purpose, seven lines were erected perpendicular to the occlusal plane on a lateral cephalogram. The position of points A and B were determined on each of the vertical lines by calculating one anterior and one posterior angle in each case. In this way, the positions of all A- and B-points were clearly defined in the sagittal vertical plane.
The characteristic of the ANB angle in the sagittal vertical plane was graphically represented by determining both points A and B using two angles instead of one. This revealed that the ANB angle for the same sagittal base relationship was characterized by major variations depending on the position of the A- and B-points in relation to the anterior cranial base. The larger the SNA and SNB angles were, the larger the corresponding ANB angle. At the same time, the absolute value of ANB increased with the length of the vertical distance between the points A and B.
The ANB angle is strongly influenced by geometric factors. Accurate diagnosis of the sagittal base relationship should thus take the individual character of the ANB angle into account.
Fortschritte der Kieferorthopädie 04/2009; 70(2):152-8. · 0.89 Impact Factor
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ABSTRACT: The aim of this study was to evaluate the time requirement of a newly developed device made of neodymium-iron-boron (NdFeB) magnets for positioning a multi-stranded, canine-to-canine retainer during bonding compared with dental floss and a transfer tray. Forty-five patients aged between 12 and 33 years (26 male, 19 female) previously treated with fixed appliances were enrolled in the study. The patients were randomly allocated to three groups (15 per group). For each group a mandibular canine-to-canine retainer of 0.018 inch Dentaflex multi-stranded wire (Dentaurum) was prefabricated for each patient on a cast. The bonding procedure was identical, except for the method of positioning the wire during adhesive fixation: group A dental floss, group B a small prefabricated transfer tray of dental resin and group C the NdFeB magnet device. For each group, the time required for the complete bonding process was measured. Kruskal-Wallis and Wilcoxon-Mann-Whitney tests were used for group and pairwise comparisons, respectively. The three methods required statistically significant different times (P < 0.001). The Wilcoxon-Mann-Whitney test revealed that wire positioning with the magnet device was significantly faster [4.98 minutes; standard deviation (SD) 0.68 minutes] than with dental floss (7.65 minutes, SD 1.14 minutes; P = 0.0001) or with transfer tray (5.75 minutes, SD 0.57 minutes; P = 0.001). The NdFeB magnet device is a timesaving appliance for positioning a multi-stranded, canine-to-canine retainer during bonding when compared with dental floss and an individually prefabricated transfer tray.
The European Journal of Orthodontics 08/2008; 30(5):433-6. · 0.89 Impact Factor
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ABSTRACT: Our aim was to evaluate the capacity of flat-panel volume computerized tomography (fpVCT) to enable the observer to detect and differentiate 3 different sizes of simulated tooth root defects in radiographs.
Three simulated tooth root defects of different sizes and a defect-free area (160 sites in total) were randomly distributed on the buccal and lingual surface of 20 mandibular premolar roots of Sus scrofa domestica with round burs. For the imaging of the specimens, an fpVCT prototype was used. Findings were evaluated by 3 observers.
Cavity 0 (no lesion) was correctly identified in 53%, cavity 1 in 69%, cavity 2 in 96%, and cavity 3 in 89%. Altogether, the simulated cavities were classified in a correct manner in 77%. The values were compared using receiver operating characteristic curves. The area under the curve (AUC) for cavity 0 versus the pooled results for cavities 1-3 was found to be 0.72. The AUC for the pooled results for 0-2 (no pathologic impact) versus cavity 3 (potential pathologic impact) was 0.94. There was no significant dependence of the results on the observer (P = .37). Results with P < .05 were considered to be significant.
Flat-panel volume computerized tomography, which is currently used only as a research tool, has a high potential in detection and differentiation at an early stage of external root resorption cavities with pathologic relevance..
Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics 07/2008; 107(2):272-8. · 1.50 Impact Factor
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ABSTRACT: Examinations of the curvature morphology of the temporomandibular joints (TMJs) in macerated human skulls yielded that in initial protrusive cranial border motion, parts of the condylar articulating surfaces are only functional under force transmission. These areas were found on the lateral-central side of the condyle. In contrast to the Cercopithecus mona, a monkey species, the human TMJ apparently possesses a distinctly higher spatial performance range.
Annals of Anatomy - Anatomischer Anzeiger 02/2007; 189(4):339-41. · 1.86 Impact Factor
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ABSTRACT: The subject of this study was to analyse how functional parameters of stomatognathic systems are influenced by growth. For this purpose, two cephalometric radiographs of 65 patients with class-II-relation treated with functional appliances were superimposed on the occlusal plane. The two patient groups consisted of 32 open bite and 33 deep bite cases. The direction of the condylar growth significantly differed for both cases. Nevertheless the hypothesis could be confirmed that the original functional structure was hardly affected by growth.
Annals of Anatomy - Anatomischer Anzeiger 02/2007; 189(4):404-6. · 1.86 Impact Factor
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ABSTRACT: For the physiological intact stomatognathic system, the three main functional states (occlusat articular functions, free mandibular movements, and ideal bolus function) were biomechanically discussed concerning the structure of movement, rolling-gliding characteristics, and force transfer in the temporomandibular joint (TMJ). In all three cases, rolling is not possible in the TMJ since the instantaneous rotational axis is positioned outside of the joint-rolling is not necessary because the TMJ is not loaded by appreciable forces. In the aged stomatognathic system with a lost discus and considerable Loads in the TMJ, however, the attrition of the joint is eased by rolling movement at the articulating surfaces. The destruction of the discus can be seen as a physiological adaptation which brings back the joint to an original odontogen condition.
Annals of Anatomy - Anatomischer Anzeiger 02/2007; 189(4):393-6. · 1.86 Impact Factor
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ABSTRACT: The primary aim of the study was to reveal whether the free opening movement of the mandible can be determined by only 2 rotational axes as suggested in recent literature. For this purpose, the free opening movement of the mandible was registered in 20 asymptomatic patients using an ultrasonic measuring system. Subsequently, the locations of the instantaneous centers of rotation (ICR) were determined directly from the raw data. In a second approach, the same data were used to construct a mandibular and maxillar rotational axis according to the dimeric link chain (DLC) concept. On the basis of the angular velocities around these 2 axes, the positions of the ICR were calculated in the sagittal-vertical plane. Calculating the ICR by the DLC method provides similar results to that of the conventional approaches. It can be concluded that the DLC method is a valid approach and that considering the planar mandibular movement as a movement with 2 degrees of freedom is justified.
Annals of Anatomy - Anatomischer Anzeiger 02/2007; 189(4):390-2. · 1.86 Impact Factor
