Comparison of hyoid bone positions among patients with different sagittal skeletal malocclusions / 口腔疾病防治

Objective@# To compare the hyoid bone position among patients with different sagittal skeletal malocclusions to provide a reference for clinicians to formulate treatment plans.@*Methods@#Lateral cephalograms of 284 orthodontic patients were selected. According to ANB angles, the types of skeletal malocclusion of patients were determined as follows: Class Ⅰ (1° ≤ ANB ≤ 5°), Class Ⅱ (ANB>5°) and Class Ⅲ (ANB<1°). Ten parameters were used to determine hyoid positions. After comparing the hyoid positions of the three groups, stratified analyses based on sex and age were conducted. @*Results @# No significant differences in demographic and vertical facial type features among skeletal Classes Ⅰ, Ⅱ and Ⅲ patients were observed (P>0.05). The angle between the Gonion-hyoid point line and the hyoid point-Menton line (Go-Hy-Me) of Class Ⅱ patients was significantly smaller than that of Class Ⅰ patients, and the angle between the most anterior and inferior point of the third cervical vertebra-hyoid point line and the hyoid point-Sella line (C3-Hy-S) of Class Ⅲ patients was smaller than that of Class I patients (P<0.05). Age-stratified analysis showed that in the juvenile group, the C3-Hy-S of Class Ⅲ patients was significantly smaller than that of Class Ⅰ patients in males and females (P<0.05). In the adult female group, the Go-Hy-Me of Class Ⅱ patients was significantly smaller, and the distance from the hyoid point to the mandibular plane (Hy-MP) was larger than that noted in Class Ⅰ patients (P<0.05); no significant difference in hyoid position between male Class Ⅱ and I patients was observed (P>0.05).@*Conclusions@#Compared with Class Ⅰ patients, the hyoid bone of Class Ⅱ patients in adult females was farther away from the mandible and that of Class Ⅲ patients in juveniles was farther away from the cervical vertebra and posterior cranial base.

Consideraciones Metodológicas en el Estudio Histomorfométrico del Hueso Interradicular de los Primeros Molares Inferiores de Ratas Wistar / Methodological Considerations in the Histomorphometric Study of the Interradicular Bone of the First Lower Molars of Wistar Rats

El objetivo fue evaluar el volumen óseo BV/TV (%) del hueso interradicular en ratas Wistar: A) en relación a la edad; B) en relación a la zona de estudio en animales de la misma edad. Se utilizó Grupo A) 15 ratas Wistar hembras de 6 (I), 10 (II) y 14 (III) semanas, Grupo B) 9 ratas Wistar macho de 8 semanas. Tras la eutanasia, se extrajeron los maxilares inferiores y se procesaron histológicamente para obtener cortes mesio-distales del primer molar inferior coloreados con H.E. Sobre microfotografías digitales se evaluó el BV/TV (%). El análisis estadístico se realizó en A) mediante ANOVA y Bonferroni test y en B) se calculó el rango (R). Los resultados en A) el BV/TV (%) aumenta significativamente con la edad de los animales; en B) se encontró que el BV/TV (%) varía hasta un 20% si se considera el volumen total y este rango disminuye a 8.3% al estudiar su mitad coronal. En conclusión, el BV/TV (%) del hueso interradicular del primer molar inferior de ratas Wistar varía considerablemente con la edad de los animales y en animales de una misma edad -según se considere evaluar todo el hueso interradicular del espacio alveolar o la mitad superior del mismo-. Los resultados de este trabajo recomiendan emplear animales de la misma edad y realizar mediciones histomorfométricas empleando la mitad coronal de dicho hueso, especialmente en los diseños de periodontitis experimental (AU)

Cbct Analysis Of Alveolar Bone Dimensions In Mandibular Posterior Teeth: A Preliminary Study

OBJECTIVES: Extraction of mandibular posterior teeth followed by immediate implant placement is considered as an optimal technique of immediate prosthetic rehabilitation. The analysis of alveolar bone dimensions with Cone Beam Computerized Tomography prior to implant placement is a prime determinant in treatment planning. Hence this preliminary study was conducted to analyze the alveolar bone dimensions in dentate mandibular posterior teeth to evaluate the available bone which can be utilized for immediate implant placements. MATERIALS AND METHODS: Retrospective data of 200 cases of full volume CBCT was procured from Riyadh Elm University (REU) database and reviewed for eligibility. Atotal of 10 cases were included in the study. Scans were assessed for thickness of buccal and lingual walls at 4mm below the CEJ (MP1) and at midroot level (MP2). Alveolar width was assessed at most coronal point on alveolar bone (BW1) and at superior border of mandibular canal (BW2). The height was be calculated by measuring the vertical distance between BW1 and BW2. Data was tabulated and statistically analyzed using unpaired t-test. RESULTS: The results of our study indicates that dimensions of buccal and lingual bone walls of all teeth at MP1 and MP2 in PM1, PM2 and M1 were statistically significant. Also only the 1st premolar (PM1) showed statistical significance with regard to dimensions at BW1 and BW2. CONCLUSION: The present study highlights the need for further studies with larger samples which can impact the immediate implant success rates in mandibular posterior teeth

Time series observation on microstructure development of mandibular bone under different occlusal force in rats / 实用口腔医学杂志

Objective: To study the microstructure development of mandibular bone in rats on timing sequence and under different occlusal force. Methods: 63 male SD rats aged 23 days were randomly divided into three groups (n = 7): Baseline group, soft-diet (SD) group and hard-diet (HD) group. 7 rats were killed at week 0, 2, 4, 6 and 8 respectively after feeding the food with different hardness.Micro-CT was used to reconstruct and analysis microstructure of the region of interest in mandible of the rats. Results: Compared with HD group, bone volume/total volume (BV/TV) and trabecular thickness (Tb. Th) decreased significantly after 4 th week (P ＜ 0. 05), the bone surface/bone volume (BS/BV) and trabecular separation (Tb. Sp) increased significantly during the 4 th to the 6 th week (P ＜0. 05) . Conclusion: In the process of mandibular development in rats, reduction of occlusal force may lead to reduction of bone mass, and the changes of microstructure are closely related to the time of intervention.

Mandibular bone necrosis after use of paraformaldehyde-containing paste

Paraformaldehyde has been used in the past as a pulpotomy agent. However, it has a severe cytotoxic effect and may cause alveolar bone necrosis. Depulpin, a devitalizing agent containing 49% paraformaldehyde, is no longer used frequently due to its severe side effects. In the two cases described in the present study, Depulpin was used as a devitalizing agent during root canal treatment. It caused a gradual loss of sensibility in adjacent teeth, gingival necrosis, and osteomyelitis. This case report demonstrates the serious side effects of using a paraformaldehyde-containing paste as a devitalizing agent for pulp, particularly mandibular bone necrosis.

Three-dimensional structure and morphology of the mandible in type 1 diabetes mellitus mice / 中国组织工程研究

BACKGROUND: Diabetes mel itus is one of the most common systemic diseases, which often leads to the changes of the jaw and other bone structure, as wel as the abnormal changes of mineral metabolism. OBJECTIVE: To observe the three-dimensional structure and histopathological changes of the mandible in type 1 diabetes mel itus mice. METHODS: The mice were randomly divided into control group and diabetes mel itus group. The diabetes mel itus group received intraperitoneal injection of 50 mg/kg streptozotocin for 5 days to establish a type 1 diabetes mel itus model, and the control group received intraperitoneal injection of citrate buffer. RESULTS AND CONCLUSION: At 3 weeks after modeling, the micro-CT technique was used to observe the three-dimensional structure of the mandibles in the two groups. The quantitative analysis on the microstructure of cancel ous bone and cortical bone showed that the bone mineral density, bone volume fraction, trabecular number and trabecular thickness of cancel ous bone in the interest region in the mandible of type 1 diabetes mel itus mice were significantly decreased when compared with that in the control group (P < 0.01, P < 0.05), while the structure model index was increased significantly (P < 0.05); the mineral density and area of cortical bone were decreased in the diabetes mel itus group (P < 0.05). Hematoxylin-eosin staining showed that the number and volume of mandibular trabeculae of type 1 diabetes mel itus mice were decreased. The results suggest that the three-dimensional structure of the cancel ous bone and cortical bone in the streptozotocin-induced type 1 diabetes mel itus mice are changed significantly, and the microstructure change of the cancel ous bone is more obvious.

Correlação entre a densidade óssea mandibular, femural, lombar e cervical / Correlation among mandibular, femoral, lumbar and cervical bone density

INTRODUÇÃO: diante da maior frequência de pacientes adultos que se submetem atualmente ao tratamento ortodôntico, as condições gerais de saúde dessa faixa etária têm sido motivo de investigações correlacionadas aos eventos ligados ao metabolismo ósseo, haja vista que os movimentos dentários são dependentes do processo de remodelação óssea, ainda que num nível local. Diferentes padrões de densidade óssea podem acarretar diferentes respostas ao movimento ortodôntico. OBJETIVOS: o presente estudo avaliou a correlação da densidade mineral óssea (DMO) geral com aquela da região mandibular. MÉTODOS: para tanto, 22 mulheres saudáveis, com idades entre 30 e 45 anos, foram selecionadas para os exames de densitometria óssea das regiões lombar, cervical e femural, bem como da região mandibular. Foram testadas as correlações entre essas leituras e, também, estabelecidos valores de referência para as áreas cervical e mandibular. RESULTADOS: os resultados não demonstraram correlação significativa entre a densidade mandibular e as demais áreas estudadas. Houve correlação significativa apenas entre a região cervical e a femural. O valor médio DMO normal para a região mandibular foi de 0,983g/cm² (d.p. = 0,334), enquanto para a região cervical foi de 0,768g/cm² (d.p. = 0,102), e os valores médios para a região lombar e femural foram de, respectivamente, 1,127g/cm² (d.p. = 0,067) e 0,925g/cm² (d.p. = 0,078), esses últimos semelhantes aos valores de referência da Organização Mundial de Saúde. CONCLUSÕES: sugere-se que o exame da área femural possa abranger o valor esperado para a área cervical, entretanto há necessidade do exame densitométrico particular para a área mandibular, não sendo adequada a extrapolação dos valores tradicionais (lombar e femural) para estimativa dessa área. Estudos adicionais são necessários para avaliar as variações densitométricas locais e eventual influência sobre a movimentação ortodôntica.

INTRODUCTION: Due to the rise in frequency of adult patients who currently are submitted to orthodontic treatment, general health conditions of this age have been a reason of inquiries correlated to events related to bone metabolism, as dental movements are dependent on the process of bone remodeling, even though in a local level. Different standards of bone density can give different answers to the orthodontic movement. AIM: The present study evaluated the correlation of the general bone mineral density (BMD) to the mandibular region. METHODS: Therefore, 22 healthy women aged between 30 and 45 years old were selected for bone densitometry examinations of lumbar, cervical, femoral, as well as mandibular alveolar region. The correlations to these readings were tested as well as values of reference were established for cervical and mandibular areas. RESULTS: The results did not demonstrate significant correlation among the mandibular density to the others studied areas. There was only significant correlation between cervical and femural region. Normal BMD average value for mandibular region was 0.983g/cm² (SD = 0.334), whereas for cervical region was 0.768g/cm² (SD = 0.102), and the average values for lumbar and femoral regions were respectively 1.127g/cm² (SD = 0.067) and 0.925g/cm² (SD = 0.078), these last ones were similar to the reference values of World Health Organization (WHO). CONCLUSIONS: It is suggested that the examination of the femoral area can comprehend the expected value to cervical area, however particular densitometry examination for the mandibular area is needed, and the exploration of the traditional values (lumbar and femoral) is not appropriate to the estimative of this area. Additional studies are necessary to evaluate local density variations and its influence on orthodontic movement.

Mandibular bone regeneration using autogenous skin-derived precursor cells with a mixed demineralized bone and fibrin glue scaffold in miniature pigs

Cone beam tomography evaluation of lingual cortical mandibular defect diagnosed as Stafne bone cavity / Cone beam tomography evaluation of lingual cortical mandibular defect diagnosed as Stafne bone cavity

Mandibular lingual bone depressions are considered to be developmental anomalies known as Stafne bone cavity. The purpose of the present report is to describe the characteristics of classic Stafne bone cavity in molar region evaluated by cone beam computed tomography (CBCT). A male patient, 27 years old, was submitted to CBCT to evaluation the relation between the right lower third molar roots and mandibular canal and the unilateral cystic image found in the panoramic radiographic below the mandibular canal in the right molar area. It was used a gray scale of 12 bits and voxel of 0.2 mm. The CBCT showed fine images of the Stafne bone cavity. In the present case, periodic clinical and radiological controls were the therapeutic option. In atypical cases or in doubtful diagnosis, surgical intervention and anatomopathological examination may be indicated. Although the diagnosis of a Stafne bone cavity can often be established with plain radiographs, confirmatory tests are sometimes required. In these situations, the diagnosis can be confirmed with CBCT.

Finite Element Analysis of Stress Distribution on Telescopic System for Mandibular Implant Supported Overdenture / 대한치과보철학회지

PURPOSE: The purpose of this study was to investigate the stress distribution in mandibular implant overdentures with telescopic crowns compared to bar attachment. MATERIAL AND METHODS: Three-dimensional finite element models consisting of the mandibular bone, 4 implants, and primary bar-splinted superstructure or secondary splinted superstructure with telescopic crowns were created. Vertical and oblique loads were directed onto the occlusal areas of the superstructures to simulate the maximal intercuspal contacts and working contacts such as group function occlusion. Maximum stress and stress distribution were analysed in mandibular bone, implant abutments, and superstructures. RESULTS: 1. In comparison of von Mises stress on mandibular bone, telescopic overdenture had a little lower stress values in vertical load and working side load except oblique load. In the mandible, the telescopic overdenture distributed more uniform stress than the bar overdenture. 2. In comparison of von Mises stress on implant abutments, telescopic overdenture had much lower stress values in all load conditions. In implant abutments, the telescopic overdenture distributed stress similar to the bar overdenture. Stress was concentrated on the distal surfaces of the posterior implant abutments in both mandibular overdentures. 3. In comparison of von Mises stress on superstructures, the telescopic overdenture had much more stress values in all load conditions. However, the telescopic overdenture distributed more uniform stress on superstructure than the bar overdenture. In the bar overdenture, stress was concentrated on each cental area of bar structures and connected area between implant abutments and bar structures. CONCLUSION: In the results of this study, the telescopic overdenture had lower stress values than the bar overdenture in mandibular bone and implant abutments, but more stress values in superstructures. However, if optimal material was selected in making superstructures, the telescopic overdenture was compared to the bar overdenture in stress distribution.

Radiological Morphometric Analysis of the Mandibular Bone Structure after Ovariectomy in Mature Cynomolgus Monkeys / Oral Science International

[Purpose] The effects of experimental osteoporosis on the trabecular bone structure of the mandible in cynomolgus monkeys were examined by radiological bone morphometric analysis. [Methods] Ovariectomy (OVX) was performed on twelve 10-year-old female cynomolgus monkeys, which were fed a controlled diet for 2 years. Twelve monkeys in a sham control group were fed under the same conditions. Using a microfocus tube and computed radiography, the removed mandibular bone samples were imaged by standardized magnification radiography, and two-dimensional digital imaging data were obtained. The structural parameters, such as skeletal area, perimeter, number, complexity, continuity and anisotropy, were measured using radiological bone morphometric analysis. The bone mineral density (BMD) was measured by dual energy X-ray absorptiometry. The width of the cortical bone was measured using magnified radiographic images. [Results] There were no significant differences between the OVX and the sham control groups in the skeletal structure indicated by the skeletal volume, number, width, perimeter, complexity, continuity, separation and spacing. However, there were significant differences between the two groups in the BMD of the mandibular body, cortical bone width, anisotropy and some parameters of the skeletal continuity. Among these parameters, the difference in the thinning of the cortical bone was most significant. [Conclusions] Using two-dimensional digital radiographic image data, this study suggests that the cortical bone width is more useful than the trabecular bone structure as the morphologic parameter for diagnosis of osteoporosis in the mandibular body.

Experimental Study of Early Repair of Mandibular Defect Following High Velocity Missile Wound / 中华创伤杂志

This study was done based on the principle of early repair of mandible defect after firearms wound. The results showed that the delayed one stage reconstruction could be used to repair of maxillofactial defect caused by firearms wound, using vascularized graft was supperior to the free bone graft alone. The latter is not suitable for the repair of maxiUofacial firearms defects in early stage.