Development of craniofacial superimposition: a review / Desarrollo de la superposición craneofacial: una revisión

SUMMARY: Craniofacial superimposition is a method for identifying individuals by using secondary data in order to identify a target group of persons before a DNA process can be used, or to identify an individual instead of using primary data in cases where DNA, fingerprint or dental records are not found. Craniofacial superimposition has continued to evolve, with various techniques, including computer-assisted and photography techniques, to help the operation be more convenient, faster and reliable. The knowledge of forensic anthropology is applied, with a comparison between anatomical landmarks. The study of developments in craniofacial superimposition using computer-assistance has yielded satisfactory results.

La superposición craneofacial es un método para identificar individuos mediante el uso de datos secundarios, se utiliza para identificar un grupo objetivo de personas, antes de que se pueda utilizar un proceso de ADN, o para identificar a un individuo en lugar de utilizar datos primarios en los casos en que no se cuenta con registros de ADN, huellas dactilares o dentales. La superposición craneofacial ha seguido evolucionando, con diversas técnicas, incluidas las técnicas fotográficas y asistidas por computador, para ayudar a que la operación sea más conveniente, rápida y confiable. Se aplica el conocimiento de la antropología forense, con una comparación entre hitos anatómicos. El estudio de la evolución de la superposición craneofacial con asistencia informática ha arrojado resultados satisfactorios.

Evaluation of adjacent tooth displacement in the posterior implant restoration with proximal contact loss by superimposition of digital models

PURPOSE: This study was conducted to investigate patterns of adjacent tooth displacement in the posterior implant with interproximal contact loss (ICL) by 3-D digital superimposition method. MATERIALS AND METHODS: Posterior partially edentulous patients, restored with implant fixed partial prostheses before 2011 and suffered from food impaction of ICL between 2009 and 2011, were included. Two dental casts, at the time of delivery and at the time of food impaction in a same patient, was converted into 3-D digital models through scanning and superimposition was performed to assess chronologic changes of the dentition. Directions of tooth displacement were evaluated and the amount of ICL was calculated. Correlations between the amount of ICL and elapsed time, or between the amount of ICL and age after function, were assessed at a significance level of P.05). CONCLUSION: Natural teeth showed various directional movements to result in occlusal change in the arch. The 3-D superimposition of chronologic digital models was a helpful method to analyze the changes of dentition and individual tooth displacement adjacent to implant restoration.

Preliminary Study of Craniofacial Superimposition by Mathematics Programming in a Thai Population

@#Craniofacial superimposition are used in cases where one has found an unknown human skull. The purpose of this research was to develop craniofacial superimposition by applying mathematical programme to increase the credibility of craniofacial superimposition in Thailand. To calculate the overlay position of face-real skull photo and face photo from the same owner were compared to the face-randomised skull photo and face photo. This study was carried out on a sample of 20 skulls, divided into 10 male skulls and 10 female skulls. All samples of bones were taken from the Forensic Osteology Research Center (FORC), Faculty of Medicine, Chiang Mai University. Skull and face photography of the deceased took only the front-straight face position. The similarity was found out from edges of them that compared at important points with the mathematical programme, in which the researchers applied functions and mathematical principles of matrix and logical. In each individual experiment between face-real skull and face-randomised skull, the results were recorded and explained in the form of qualitative experiments. From the experiment found that the used programme can be able to correctly assess the similarity are 19 cases of 20 cases. Craniofacial superimposition can save the budget of DNA testing and can be screening for the initial assumption. This research will be able to facilitate, work faster, more reliable and save budget in the identifying process.

Effect of abutment superimposition process of dental model scanner on final virtual model / 대한치과보철학회지

PURPOSE: The purpose of this study was to verify the effect of the abutment superimposition process on the final virtual model in the scanning process of single and 3-units bridge model using a dental model scanner. MATERIALS AND METHODS: A gypsum model for single and 3-unit bridges was manufactured for evaluating. And working casts with removable dies were made using Pindex system. A dental model scanner (3Shape E1 scanner) was used to obtain CAD reference model (CRM) and CAD test model (CTM). The CRM was scanned without removing after dividing the abutments in the working cast. Then, CTM was scanned with separated from the divided abutments and superimposed on the CRM (n=20). Finally, three-dimensional analysis software (Geomagic control X) was used to analyze the root mean square (RMS) and Mann-Whitney U test was used for statistical analysis (α=.05). RESULTS: The RMS mean abutment for single full crown preparation was 10.93 µm and the RMS average abutment for 3 unit bridge preparation was 6.9 µm. The RMS mean of the two groups showed statistically significant differences (P<.001). In addition, errors of positive and negative of two groups averaged 9.83 µm, −6.79 µm and 3-units bridge abutment 6.22 µm, −3.3 µm, respectively. The mean values of the errors of positive and negative of two groups were all statistically significantly lower in 3-unit bridge abutments (P<.001). CONCLUSION: Although the number of abutments increased during the scan process of the working cast with removable dies, the error due to the superimposition of abutments did not increase. There was also a significantly higher error in single abutments, but within the range of clinically acceptable scan accuracy.

Modified Bisecting Angle Technique: A Novel Method to Eliminate Zygomatic Superimposition over the Apices of Maxillary Molars

Objectives Intra oral radiographic imaging is the most widely used method for obtaining information about root canal anatomy and working length determination. Measuring exact working length is the most essential step for the success of root canal treatment. Bisecting angle technique (BAT) is the most widely used technique for this purpose. However, zygomatic superimposition over the apices of maxillary molars makes it difficult for the dentist to estimate exact working length. The present study made certain modifications in BAT to overcome these undiagnostic shadows. The aim of the study is to compare three techniques, namely paralleling cone technique (PCT), BAT and modified bisecting angle technique (MBAT) to prevent such superimposition over molar apices. Materials and Methods A total of 53 patients requiring endodontic treatment for maxillary molars were included in the study. Three radiographs one with each PCT, BAT, MBAT were made. Each radiographic image was recorded acceptable or unacceptable based on the zygomatic superimposition. The data thus collected was subjected to statistical analysis using chi-square test. Results The percentage of acceptability in MBAT was 56.6% (n = 30) when compared with BAT which was only 28.3% (n = 15) and PCT was 58.3% (n = 31) indicating statistically significant difference between BAT and MBAT. But no statistically significant difference was found between MBAT and PCT. Conclusion In the present study, MBAT was found to be more accurate than BAT, and it was relatively as accurate as PCT in eliminating zygomatic superimposition over the apices of maxillary molars.

Evaluation of the invisible bracketless appliance on maxillary molar distalization / 实用口腔医学杂志

Objective:To evaluate the clinical effects of invisible bracketless appliance on the upper molar distalization.Methods:15 patients with class Ⅱ malocclusion(at the average age of 25.3 years) were treated by invisible bracketless appliance,the pre and post three-dimensional digital models were superimposed and measured,the effects of molar distalization were analysed.Results:After treatment,the maxillary first molars were distalized by 2.58 mm on both sides.The left and fight second molars were distalized by 2.57 mm and 2.68 mm respectively.Bilateral central incisors were moved mesially by 0.34 mm.There was no significant difference in the horizontal movement of central incisor.But the left and fight first molars were moved buccally by 0.96 mm and 0.97 mm respectively,the left and fight second molars were moved buccally by 1.01 mm and 1.11 mm separately.Bilateral first molars were intruded by 0.26 mm,the left and right second molars were intruded by 0.37 mm and 0.36 mm,respectively.But the central incisors had no significant vertical movement.There was no significant difference in the buccally or palatally rotation of bilateral first and second molars.Conclusion:Invisible bracketless appliance is efficient for distalization of upper molar,but it may result in mild molar intrusion and anterior anchorage loss.

Total intrusion and distalization of the maxillary arch to improve smile esthetics / 대한치과교정학회지

This case report illustrates the successful treatment of a patient with skeletal Class II malocclusion and an unesthetic smile involving excessive gingival display and large buccal corridors. By applying dual buccal interradicular miniscrews, total intrusion of the maxillary dentition along with distalization was induced to improve both the occlusion and smile esthetics. In addition to the conventional cephalometric superimposition, three-dimensional superimposition was performed and evaluated to validate the treatment outcome.

Evaluation of the marginal and internal gaps of three different dental prostheses: comparison of the silicone replica technique and three-dimensional superimposition analysis

PURPOSE: The purposes of this study were to evaluate the marginal and internal gaps, and the potential clinical applications of three different methods of dental prostheses fabrication, and to compare the prostheses prepared using the silicone replica technique (SRT) and those prepared using the three-dimensional superimposition analysis (3DSA). MATERIALS AND METHODS: Five Pekkton, lithium disilicate, and zirconia crowns were each manufactured and tested using both the SRT and the two-dimensional section of the 3DSA. The data were analyzed with the nonparametric version of a two-way analysis of variance using rank-transformed values and the Tukey's post-hoc test (α = .05). RESULTS: Significant differences were observed between the fabrication methods in the marginal gap (P .350), deep chamfer (P > .719), and axial wall (P > .150). As the 3DSA method is three-dimensional, it allows for the measurement of arbitrary points. CONCLUSION: All of the three fabrication methods are valid for measuring clinical objectives because they produced prostheses within the clinically acceptable range. Furthermore, a three-dimensional superimposition analysis verification method such as the silicone replica technique is also applicable in clinical settings.

Superimposition: a simple method to minimize occlusal adjustment of monolithic restoration / 대한치과보철학회지

The development of translucent zirconia enabled clinicians to choose a monolithic zirconia crown as one treatment modality in the posterior dentition. Careful occlusal adjustments are recommended for monolithic zirconia crowns because grinding zirconia inevitably causes phase transformation, which may deteriorate mechanical properties. intraoral scanners enable the clinician to scan and superimpose a complete tooth structure before preparation onto the prepared abutment. This technique helps to reproduce the original tooth form and occlusion of the patient. In this case report, prostheses were fabricated for patients with cracked or fractured tooth by applying intraoral scanner, Computer aided design-computer aided manufacturing (CAD-CAM) and monolithic zirconia crown to reproduce the occlusion of original tooth and to minimize occlusal adjustment. The clinical results were satisfactory in both esthetic and functional aspects.

Fusión de imágenes y protección de hipocampo para el tratamiento de metástasis cerebrales con radioterapia / Image fusion and hippocampus protection in radiotherapy treatment of brain metastases

Las imágenes de simulación obtenidas mediante TAC son actualmente el estándar para uso en los sistemas de planificación de haces externos empleados en los tratamientos de radioterapia. Sin embargo, una de las limitaciones es su bajo contraste y poca especificidad para la identificación y caracterización de lesiones tumorales y algunas estructuras a nivel de sistema nervioso central. Los nuevos algoritmos implementados en los sistemas de planificación de radioterapia permiten realizar la fusión de imágenes de RM con TAC de simulación, definir y proteger estructuras como el hipocampo, buscando administrar dosis bajas en esta zona, lograr mayores dosis a los volúmenes tumorales y disminuir los efectos secundarios derivados de tratamientos holoencefálicos con radioterapia. En este artículo se presentan las imágenes correspondientes a esta técnica de tratamiento.

CT simulation images are the current standard in external beam radiotherapy planning systems. However, the limitations of images obtained from CT scanning include their low contrast and low specificity in the identification and characterization of tumor lesions and some central nervous system structures. The new algorithms implemented in radiotherapy planning systems allow image fusion to be performed using MRI images and CT simulation images. It also allows structures like the hippocampus to be defined and protected, by administering lower Radiosurgery; doses to this area and higher doses to the tumor volume, thus decreasing side effects arising from whole brain radiotherapy treatment. Images corresponding to this treatment technique are presented in this article.

Three dimensional accuracy analysis of dental stone casts fabricated using irreversible hydrocolloid impressions

PURPOSE: The objects of this study was to evaluate the accuracy of the dental stone casts made from alginate impressions according to storage condition and stone pouring time. MATERIALS AND METHODS: Each of upper and lower impressions of dental model was taken. The dental stone models were made immediately, 10, 30, 60, 180, 360 minutes after the impressions were taken at each storage condition. 3D models were constructed by scanning the stone model using 3D laser scanner. With Reference points, positioned on digital models, linear measurements of the dimensional change were compared by 3D metrology software, 3D average models were made and superimposition to identify the specific site of dimensional change and to measure surface deviation (mm). RESULTS: Dental stone models which were made immediately after taking the impression showed the smallest linear dimensional change. As the stone pouring time was prolonged, the linear dimensional change was increased. More than 180 minutes after impression taking, linear dimensional change and surface distortion increased in the posterior molar region, regardless of the storage condition. CONCLUSION: For the optimum accuracy of the dental stone casts, alginate impression should be poured as soon as possible. If there were a need for storing, a humidor with 100% relative humidity must be used and be stored less than 180 minutes to fabricate the accurate dental model.

A reliable method for evaluating upper molar distalization: Superimposition of three-dimensional digital models / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. METHODS: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. RESULTS: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. CONCLUSIONS: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

A reliable method for evaluating upper molar distalization: Superimposition of three-dimensional digital models / 대한치과교정학회지

OBJECTIVE: The aim of this study was to evaluate the reliability of measurements obtained after the superimposition of three-dimensional (3D) digital models by comparing them with those obtained from lateral cephalometric radiographs and photocopies of plaster models for the evaluation of upper molar distalization. METHODS: Data were collected from plaster models and lateral cephalometric radiographs of 20 Class II patients whose maxillary first molars were distalized with an intraoral distalizer. The posterior movements of the maxillary first molars were evaluated using lateral cephalometric radiographs (group CP), photocopies of plaster models (group PH), and digitized 3D models (group TD). Additionally, distalization and expansion of the other teeth and the degrees of molar rotation were measured in group PH and group TD and compared between the two groups. RESULTS: No significant difference was observed regarding the amount of molar distalization among the three groups. A comparison of the aforementioned parameters between group PH and group TD did not reveal any significant difference. CONCLUSIONS: 3D digital models are reliable to assess the results of upper molar distalization and can be considered a valid alternative to conventional measurement methods.

Método de superposición estructural de Björk para evaluar crecimiento y desarrollo craneofacial / Björk structural superimposition method to evaluate craniofacial growth and development

La superposición cefalométrica es una herramienta indispensable en la práctica de la Ortodoncia ya que permite evaluar los cambios que sufre el complejo craneofacial a través del proceso de crecimiento y desarrollo o aquellos cambios logrados mediante un tratamiento. En la literatura se han descrito múltiples técnicas de superposición cefalométrica; la mayoría de ellas utilizan como puntos de referencia zonas anatómicas poco estables durante el periodo de crecimiento y desarrollo. El doctor Björk describió una técnica de superposición cefalométrica basada en estudios con implantes metálicos, lo cual permitió identificar puntos de referencia y zonas anatómicas mas estables durante este periodo, por lo que permite medir y valorar los cambios craneofaciales de una manera mas confiable. El Objetivo de este articulo es describir la técnica de superposición estructural de Björk para su utilización como herramienta en la practica clínica e investigativa de la Ortodoncia.

Cephalometric superimposition is a critical tool in Orthodontics when evaluating changes affecting the craniofacial complex through the process of growth and development, or those obtained with treatment. Several cephalometric superimposition techniques have been reported previously, but most of them use unstable anatomical landmarks as reference areas or points to establish changes during growth and development. Björk's method describes a cephalometric superimposition technique based on studies with metal implants which allowed to identify stable reference points during the growth and therefore enable the possibility of measuring and evaluating craniofacial changes in amore reliable manner. The objective of this article is to describe Björk structural superimposition method as a tool in clinical practice and research in Orthodontics.

Fotogrametría del perfil facial en ortodoncia / Photogrammetry of facial profile in orthodontics

Se incorporaron dos sencillos elementos en las fotografías del perfil facial en ortodoncia. La aplicación de un sello, automático, de tinta común con una escala preestablecida de aplicación fácil, ágil y reproducible, directamente sobre la piel del paciente, para otorgar mayorprecisión en la comparación de imágenes en el tiempo; como así también, la utilización de un plano de referencia denominado plano lefraconformado por dos puntos que unen ojo y oído, permitiendo evaluar los cambios producidos en el rostro por medio de la superposición fotográfica. Al finalizar el presente trabajo se concluyo que la utilización del sello y la superposición sobre el plano lefra permiten asimilar eltamaño de las fotografías y a su vez dar una zona referencial estable, facilitando la comparación entre el pre y post tratamiento.

Two simple elements were incorporated in the photographs of facial profile in orthodontics. The application of a seal, automatic, common ink on a prescribed scale of easy, fast and reproducible application, directly on the skin of the patient profile, which gives more accurate comparison of images in time; as well as the use of a reference plane called lefra plane, which consists of two points linking eye and ear, allowing to evaluate the changes in the face by means of photographic superimposition. Upon completion of this work, was concluded that the use of the seal and the overlay on the lefra plane allow to assimilate the size of the photographs and in turn provide a stable reference area to facilitate the comparison between pre and post treatment.

A method for mandibular dental arch superimposition using 3D cone beam CT and orthodontic 3D digital model / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to develop superimposition method on the lower arch using 3-dimensional (3D) cone beam computed tomography (CBCT) images and orthodontic 3D digital modeling. METHODS: Integrated 3D CBCT images were acquired by substituting the dental portion of 3D CBCT images with precise dental images of an orthodontic 3D digital model. Images were acquired before and after treatment. For the superimposition, 2 superimposition methods were designed. Surface superimposition was based on the basal bone structure of the mandible by surface-to-surface matching (best-fit method). Plane superimposition was based on anatomical structures (mental and lingual foramen). For the evaluation, 10 landmarks including teeth and anatomic structures were assigned, and 30 times of superimpositions and measurements were performed to determine the more reproducible and reliable method. RESULTS: All landmarks demonstrated that the surface superimposition method produced relatively more consistent coordinate values. The mean distances of measured landmarks values from the means were statistically significantly lower with the surface superimpositions method. CONCLUSIONS: Between the 2 superimposition methods designed for the evaluation of 3D changes in the lower arch, surface superimposition was the simpler, more reproducible, reliable method.

Validity of Superimposition Range at 3-Dimensional Facial Images

The evaluation of rotational movements of maxillary posterior teeth using three dimensional images in cases of extraction of maxillary first premolar / 대한치과교정학회지

Cephalometric superimposition is unable to evaluate tooth movement along the occlusal plane and the errors of photographing and superimposition of the occlusogram is also inevitable. The purpose of the present study was to evaluate the rotational movements of the maxillary posterior teeth following space closure after extraction of maxillary first premolars, using 3D dental images. In 19 adult females, analysis of rotational movements of the maxillary posterior teeth was performed between the initial and final 3D dental images superimposed on the maxillary hard palate. The results showed a diversity of rotational movements of posterior teeth. The causes of various rotational movements may be different rotation of molars in each case at the beginning of treatment, individual characters of the dental arch and tooth morphology. The results of the study indicate that accurate evaluation of rotational movements of posterior teeth following space closure after extraction of premolars using 3D dental images can be obtained through the subdivision of tooth movement during the initial aligning, space closure and finishing stages.

Mapping the human retina / 医疗卫生装备

Age-related macular in human retinal results in strict loss and enduring decrease in visual acuity. A lot of medical evidence has shown that macular degeneration, associated with Choroidal neovascularization (CNV), leads to irreversible injure in composition and function of retinal tissue. A new analytical and restorative treatment, scotoma-based photocoagulation (SPB), curdles the affected areas so effectively and timely that it can delay or prevent age-related macular degeneration (AMD). A scanning laser ophthalmoscope (SLO) image is involved and the function and character of scotometry are analyzed. Combining anatomical and pathological features, this paper introduces process of acquiring the image and algorithms of analyzing it. Furthermore, integrate image of retinal is extracted from SLO through feature extraction, special registration and superimposition. The treatment can be applied to clinical diagnosis without great revisions and provide direction for pertinent fields.

Subarachnoid Hemorrhage Due to a Ruptured Middle Cerebral Artery Bifurcation Aneurysm Superimposed by an Idiopathic Intracerebral Hematoma

A rare case of idiopathic subcortical intracerebral hematoma superimposed on the subarachnoid hemorrhage due to the rupture of an ipsilateral middle cerebral artery bifurcation aneurysm is reported and pertinent literatures are reviewed.