Features of condylography curves / 华西口腔医学杂志

With the kinematic face bow, the condyle movements representing temporomandibular joint function can be recorded instantly. The condylography curves can be utilized for diagnostic analysis, as different pathophysiological conditions have unique curve patterns. By tracing the specific alterations on the curves, the structural and functional statuses of the temporomandibular joint can be predicted. However, to the best of our knowledge, no standardized and practicable evaluation protocol for jaw movement tracing exists. In the current study, the features of either normal or abnormal curves were reviewed. Such features can be clinically used for determining temporomandibular joint status, thereby contributing to a comprehensive diagnosis.

El arco facial en la elaboración de las férulas oclusales tipo Míchigan / Face bows in the production of Michigan occlusal splints

Introducción: la férula oclusal tipo Míchigan (FOM) es un dispositivo usado frecuentemente para el manejo de pacientes con bruxismo. La literatura menciona el uso del arco facial para el montaje de modelos en el articulador semiajustable, sin embargo el beneficio de este en la elaboración de las FOM aún es controvertido. Por lo tanto el objetivo de esta investigación fue comparar el registro de número de puntos de contacto y el tiempo de ajuste entre las FOM elaboradas con y sin el uso del arco facial en pacientes con diagnóstico de bruxismo. Métodos: se elaboraron 90 férulas entregadas a 45 pacientes de la Clínica de Rehabilitación Benemérita Universidad Autónoma de Puebla (BUAP), previo diagnóstico de bruxismo. Las dos férulas elaboradas (una con modelos montados con arco facial y otra sin él), se compararon en el articulador y clínicamente. Se registró el número de puntos de contacto obtenidos en ambas férulas y el tiempo de ajuste requerido. Las comparaciones se hicieron con la prueba estadística de Wilcoxon y significancia menor a 0,05. Resultados: la media de puntos de contacto en boca de las férulas con el uso del arco fue superior (11,67) a la de sin uso del arco (11,58) sin diferencias significativas (p = 0,799). El tiempo de ajuste fue superior en las férulas elaboradas sin arco (51 s) que con arco (33 s), sin diferencias significativas (p = 0,332). Conclusión: no existen diferencias significativas con el uso del arco facial o sin él para la elaboración de las FOM en pacientes bruxómanos.

Introduction: Michigan occlusal splints (MOS) are frequently used for the management of patients with bruxism. The literature mentions the use of face bows for mounting models in semi-adjustable articulators, but its benefit in the production of MOS is still controversial. Therefore, the objective of this study was to compare the record of number of contact points and mounting time between MOS made with and without face bows in patients diagnosed with bruxism. Methods: a total of 90 splints were made and distributed among 45 patients diagnosed with bruxism at the Oral Rehabilitation Clinic of Benemérita Universidad Autónoma de Puebla (BUAP). The two splints (one made with a face bow mounted model and the other one without it) were compared at the articulator and clinically. The number of obtained contact points was recorded in both splints as well as the time needed for mounting. The comparisons were made with Wilcoxon statistical test and a significance level lower than 0.05. Results: the splints with face bows showed a greater average of contact points in the mouth (11.67) compared with the ones without face bows (11.58), with no significant difference (p = 0.799). Mounting time was higher in the splints made without face bows (51 s) compared with the ones with face bows (33 s), with no significant difference (p = 0.332). Conclusion: there are no significant differences in using face bows for developing MOS in bruxism patients.

Accuracy of two face-bow/semi-adjustable articulator systems in transferring the maxillary occlusal cant.

Context: The precision of an arbitrary face-bow in accurately transferring the orientation of the maxillary cast to the articulator has been questioned because the maxillary cast is mounted in relation to arbitrary measurements and anatomic landmarks that vary among individuals. Aim: This study was intended to evaluate the sagittal inclination of mounted maxillary casts on two semi-adjustable articulator/face-bow systems in comparison to the occlusal cant on lateral cephalograms. Materials and Methods: Maxillary casts were mounted on the Hanau and Girrbach semi-adjustable articulators following face-bow transfer with their respective face-bows. The sagittal inclination of these casts was measured in relation to the fixed horizontal reference plane using physical measurements. Occlusal cant was measured on lateral cephalograms. SPSS software (version 11.0, Chicago, IL, USA) was used for statistical analysis. Repeated measures analysis of variance and Tukey's tests were used to evaluate the results (P < 0.05). Results: Comparison of the occlusal cant on the articulators and cephalogram revealed statistically significant differences. Occlusal plane was steeper on Girrbach Artex articulator in comparison to the Hanau articulator. Conclusion: Within the limitations of this study, it was found that the sagittal inclination of the mounted maxillary cast achieved with Hanau articulator was closer to the cephalometric occlusal cant as compared to that of the Girrbach articulator. Among the two articulators and face-bow systems, the steepness of sagittal inclination was greater on Girrbach semi-adjustable articulator. Different face-bow/articulator systems could result in different orientation of the maxillary cast, resulting in variation in stability, cuspal inclines and cuspal heights.

Single step approach to make diagnostic impressions of both the arches and face bow transfer: A novel technique.

Context: Mounting the maxillary and mandibular dentulous casts for Diagnostic purpose requires many steps (including making maxillary and mandibular impressions, face-bow transfer, and bite registration) or many appointments. A simple new technique of doing all of this together without compromising on the accuracy can save time over the conventional mounting procedure. Aim: To compare the accuracy of a new technique of a single-step diagnostic mounting procedure with that of the conventional diagnostic mounting procedure. Materials and Methods: Ten dentulous patients with the full complement of teeth and without any history of temporomandibular disorder and orthodontic treatment were selected for this study. A detachable metal triple tray to replace the fork part of the face bow fork that further could be attached to face bow was fabricated. Dual-arch impressions and face-bow transfer were made in these subjects using this modified triple tray. These mountings were compared with the ones done with the conventional mounting procedure. Five linear measurements (using stable reference points on the articulator and the cast) were made and the values obtained by both the methods were compared. Statistical Analysis: The Student's 't' test for statistical analysis was used in this study. Results: The measurement values obtained by the single-step method were almost similar to the ones obtained by the conventional method. The various mean measurements for the single step and conventional methods were 37.7 ± 6.8 and 38.5 ± 6.5 mm; 70.0 ± 4.4 and 70.1 ± 4.2 mm; 57.0 ± 4.9 and 57.3 ± 4.2 mm; 71.3 ± 4.5 and 71.0 ± 4.6 mm; and 58.7 ± 2.5 and 58.3 ± 2.3 mm; respectively. The differences between the values obtained by the conventional and single-step methods were not statistically significant. Conclusion: The single-step procedure of diagnostic mounting can be used as an alternative to the conventional method, without compromising the quality of mounting.

Mystery Of Midline In Facebowtransfer : A Pilot Study.

Location of the transverse hing axis is an important step in mounting the casts on an articulator. The axis of the articulator shaft should coincide with the mandibular transverse hinge axis of the patient. In our routine practice the midline of the wax rim coincides with the midpoint of the face bow fork. A pilot study was carried out to observe the effect of deviation of midline of occlusal rim on the face bow fork in the saggittal plane.

A prediction of bony interference between proximal and distal segment of the mandible with integrated 3d solid model and dental cast in orthognathic surgery

Three-dimensional solid model has not been widely used in surgical prediction of orthognathic surgery because freque from occlusal restorations or prosthesis limited the usefulness of simulated surgery involving occlusion. We prepared three-dimensional(3D) solid model from CT data and integrated the 3D solid model with dental cast using a face-bow transfer technique combined with skeletal reference measurement and confirmation with cephalometric radiographs. With this simple and easy method, it was possible to predict bony interference between the proximal and distal segment of the mandible so that we can prevent condylar displacement after sagittal split ramus osteotomy of the mandible with prominent asymmetry. The method error was within 2mm and it seemed to be useful in preoperative planning for maxillofacial surgery with maxillo-mandibular occlusal change

A three-dimensional FEM comparison study about the force, displacement and initial stress distribution on the maxillary first molars by the application of various asymmetric head-gear / 대한치과교정학회지

The purpose of this study was to compare the force, the displacement and the stress distribution on the maxillary first molars altered by the application of various asymmetric head-gear. For this study, the finite element models of unilateral Cl II maxillary dental arch was made. Also, the finite element models of asymmetric face-bow was made. Three types of asymmetric face-bow were made : each of the right side 15mm, 25mm and 35mm shorter than the left side. We compared the forces, the displacement and the distribution of stress that were generated by application of various asymmetric head-gear. The results were as follows. 1. The total forces that both maxillary first molars received were similar in all groups. But the forces that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow shortened. 2. In lateral force comparison, the buccal forces that normally positioned tooth received were increased as the length of the outer-bow shortened, and the buccal forces that mesially positioned tooth received were decreased as the length of the outer-bow shortened. Though the net lateral force moved to the buccal side of normally positioned tooth as the length of the outer-bow shortened, both maxillary first molars received the buccal force. That showed "Archial Expansion Effect" 3. The distal forces, the extrusion forces and the magnitudes of the crown distal tipping that mesially positioned tooth received were increased as the length of the outer-bow shortened, and the forces that normally positioned tooth received were decreased as the length of the outer-bow was shortened. 4. The magnitude of the distal-in rotation that normally positioned tooth received were increased as the length of the outer-bow was shortened. But, mesially positioned tooth show two different results. For the outer-bow 15mm shortened, mesially positioned tooth showed the distal-in rotation, but for the outer-bow 25mm and 35mm shortened, mesially positioned tooth showed the distal-out rotation. Thus, the turning point exists between 15mm and 25mm. 5. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the compressive stress in the distobuccal root of the normally positioned tooth moved from the palatal side to the distal side and the buccal side successively as the length of the outer-bow shortened. 6. This study of the initial stress distribution of the periodontal ligament at slightly inferior of the furcation area revealed that the magnitudes of stress were altered but the total stress distributions were not altered in the mesiobuccal root and the palatal root of normally positioned tooth, and also three roots of mesially positioned tooth as the length of the outer-bow shortened.

A comparative study of TPA-Nance combined anchorage and face bow in reinforcing the maxillary first molar anchorage / 实用口腔医学杂志

0.05).Conclusions:Combined anchorage can provide maximum anchorage compared with traditional face bow and was accepted easily by patients.

Root resorption observation of molars distalized by face bow using dental positioning films / 实用口腔医学杂志

Objective:To evaluate the influence on root resorption after distalizing molars with face bow.Methods:15 cases whose molars were distalized with face bow were selected in present research. Root lengths were measured on pre-treatment and post-treatment dental films taken with the oral positioner. The distances of molar distalization were measured on cephalometric radiographs.The differences of the pre-treatment and post-treatment root lengths were evaluated by the Paired t-test.The correlation between the distance of molars distalization and the root resorption of the maxillary molars was analyzed with Pearson's correlation coefficients.Results:The root lengths between the pre-treatment and post-treatment showed a statistically significant difference(P