Unicystic Ameloblastoma ? A Case Series

Ameloblastoma is a benign, locally aggressive neoplasm that constitutes about 1–3% of the tumors of the jaw. Wide surgical excision with adequate safe margin is the most common treatment of choice. The study aimed to manage cases with unicystic ameloblastoma while preserving the continuity of the mandible (without resection). This article presents a series of cases ranging from 18 to 40 years old patients of both sexes with unicystic ameloblastoma, especially in the mandible showing more male predilection than female. All the cases presented in this article were treated by enucleation and curettage. None of the patients presented post?operative paresthesia. None of the cases went in for resection. Post?operative recovery was uneventful in all the patients. All the patients were followed up for a period of 3.5–5 years. None of the cases reported recurrence at the date of publication.

Feasibility of using cortical bone trajectory screws in osteoporotic thoracolumbar fixation based on evaluation of bone CT values at bone-screw interface / 中华创伤骨科杂志

Objective:To evaluate the feasibility of using cortical bone trajectory (CBT) screws in the osteoporotic thoracolumbar fixation by comparing the bone CT values at the bone-screw interface between traditional trajectory (TT) screws and CBT screws in patients with different bone densities.Methods:The high-resolution CT imaging data of thoracolumbar segments following thoracic or lumbar spine fractures from April 2020 to October 2022 were collected at The Second Hospital Affiliated to Wenzhou Medical University for retrospective analysis. They were divided into 3 groups: a normal bone mass group, an osteopenia group and an osteoporosis group. From each group 30 cases were chosen (90 cases in total, 36 males and 54 females). All the data were imported into Mimics 18.0 for three-dimensional bone reconstruction in which placement of TT and CBT screws was simulated on the vertebrae from T10 to L2 (non-fractured vertebrae). Regions of interest (ROI) where each simulated screw intersected the bone were segmented to measure their CT bone values. For each vertebra in each group, the relative difference percentage in average CT value of ROI between TT and CBT screws was calculated. The CT values of ROI were compared in the same group between TT and CBT screws from T10 to L2; the CT values of ROI were compared in the same screws among the 3 groups from T10 to L2; the CT values of ROI were compared between the CBT screws in the osteopenia and osteoporosis groups and the TT screws in the normal bone mass group; the relative difference percentages in average CT value of ROI between CBT and TT screws were compared between the 3 groups from T10 to L2.Results:The average CT value of ROI for CBT screws was significantly higher than that for TT screws from T10 to L2 in every group ( P< 0.001); as for the CT values of ROI for CBT and TT screws from T10 to L2, the osteoporosis group<the osteopenia group<the normal bone mass group ( P<0.001); from T10 to L2, the CT value of ROI for CBT screws in the osteopenia group was significantly higher than that for TT screws in the normal bone mass group ( P<0.001); the CT value of ROI for CBT screws in the osteoporosis group was not significantly different from that for TT screws in the normal bone mass group ( P>0.05). At T10, T12, and L1, the relative difference percentage in average CT value of ROI between CBT and TT screws was significantly higher in the osteopenia and osteoporosis groups than that in the normal bone mass group ( P<0.05), but there was no such a difference between the osteopenia and the osteoporosis groups ( P>0.05). At T11 and L2, there was no significant difference between the 3 groups in the relative difference percentage in average CT value of ROI between CBT and TT screws ( P>0.05). Conclusions:As bone mass decreases, both CBT and TT screws lead to a significant decrease in the bone density at the bone-screw interface. In patients with osteoporosis, CBT screws can still lead to a higher bone density at the bone-screw interface than TT screws, thus providing a higher strength at the bone-screw interface.

Multiscale Analysis on Changes in Bone Microstructure of Osteoporotic Rats / 医用生物力学

Objective To study changes in bone microstructure of osteoporotic rats by multiscale analysis. Methods A total of 20 5-month-old female SD rats were randomly divided into two groups, i.e., ovariectomy (OVX) group (n=12) and the SHAM group (n=8), respectively. The rats in OVX group were subjected to bilateral ovariectomy and became osteoporosis models after 8 weeks, while sham operation was performed for the SHAM group. Changes in microstructure of cortical bone and cancellous bone at tissue scale, and osteocyte lacunar-canalicular network (LCN) and extracellular matrix (ECM) at cell scale were quantitatively analyzed using Micro-CT and SR-Nano-CT. Results At tissue scale, the cross-sectional area of cortical bone in OVX group was significantly higher than that in SHAM group (P<0.05), and the bone mineral density (BMD) and thickness of cortical bone were not significantly different from those in SHAM group. The trabecular BMD, bone volume fraction, trabecular thickness and trabecular number in OVX group were significantly decreased in comparison with SHAM group (P<0.01), while the trabecular separation was significantly increased (P<0.01). At cell scale, there was no significant difference in the semiaxes of lacunae between OVX group and SHAM group, but the thickness of lacunae and the diameter of canaliculi in OVX group were significantly increased in comparison with SHAM group (P<0.05). At the same time, the porosity of cortical bone in OVX group was significantly higher than that in SHAM group at cell scale (P<0.05). Conclusions The bone microstructure in OVX group varied to different extents at tissue and cell scales. At tissue scale, the cancellous bone loss was severe, while the cortical bone had fewer changes. At cell scale, porosity of the lacunar-canalicular network significantly increased, which directly affected the BMD and strength of cortical bone. Multiscale analysis on changes in bone microstructure of OP rats has potential application value for clinical diagnosis and pathological analysis of osteoporosis.

Biomechanical Comparison of Internal Fixation by Traditional and Cortical Bone Trajectory Pedicle Screw / 医用生物力学

Objective To compare the effects of cortical bone trajectory ( CBT) and traditional trajectory ( TT)pedicle screw internal fixation on the range of motion (ROM) and rod system stress of normal and osteoporotic(OP) spines. Methods The L3-S1 finite element models of normal and OP spines were established. The screwrod system with two kinds of trajectory was used for internal fixation of the L4-5 segment, so as to simulate sixphysiological loads, namely, flexion, extension, left / right bending, left / right rotation. The effects of two internalfixation methods on ROMs and maximum equivalent stress of screws in normal and OP spines were compared.Results For both bone conditions, CBT and TT significantly reduced ROM of the fixed segment (L4-5) and theentire segment of lower lumbar spine ( L3-S1). However, the ROM decline of CBT group was slightly smaller than that of TT group, and their ROMs were similar under flexion and extension, but the ROM differences were significant under lateral bending and axial rotation. In addition, for both the normal and OP spine models, themaximum equivalent stress of screws in CBT group was significantly higher than that in TT group. Compared withTT group, the screw stress of CBT group in normal spine model under flexion and extension, lateral bending,axial rotation was increased by 27% , 268% and 58% , respectively. However, when CBT technique was used atthe same time, the OP spine model had a smaller screw stress distribution than the normal spine model.Conclusions Compared with TT technique, CBT technique can achieve higher screw stress under OP conditionand reduce screw stress concentration under normal bone condition. In addition, CBT slightly increases ROMs of each segment, which is conducive to recovery of spinal physiological function after surgery. Lateral bending and axial rotation can produce negative mechanical effects, and these two physiological loads should be avoided.

Cadaveric study of anatomical measurement of isthmus parameters of lumbar spine to guide cortical bone screw placement

SUMMARY OBJECTIVE: To reduce surgical exposure and improve accuracy, this study evaluated the anatomical distance parameter D (including D1, D2, and D3) of the lumbar isthmus for cortical bone screw insertion. METHODS: A total of 25 structurally complete lumbar dry specimens were used for lumbar anatomy measurements. The six cadaver specimens were divided into upper and lower parts on the plane of the T11-T12 vertebrae, and we use the lower parts. Therefore, six lumbar wet specimens and another four complete lumbar dry specimens were selected. The lumbar isthmus tangent point was considered a coordinate origin, and the insertion point was determined through translating the distance of D1 value to the midline of the vertebral body horizontally and then vertically moved toward inferior board of the transverse process with the distance of D3 value. RESULTS: In four dry and six wet intact lumbar specimens, cortical bone screws were placed according to the average value of the isthmus parameter D. A total of 100 trajectories were verified in specimens by X-ray and computed topography scan to evaluate the safety, accuracy, and feasibility of the surgical use of isthmus parameter D. Using this parameter, the rates of excellent screw placement were 95% (38/40) in four dry specimens and 88.7% (53/60) in six wet specimens. CONCLUSION: The isthmus parameter D is easier to use by the operator, which can improve surgical accuracy and reduce operation time. LEVEL OF EVIDENCE: Level IV, prospective study.

Finite Element Analysis on Biomechanical Properties of Traditional Trajectory and Modified Cortical Bone Trajectory / 医用生物力学

Objective To study mechanical properties of traditional trajectory (TT) and modified cortical bone trajectory (MCBT) on osteoporotic vertebrae through finite element analysis. Methods The three-dimensional model of L4 segment was established, and pedicle screw (PS) (diameter 6.0 mm, length 45 mm) and MCBT screw (diameter 4.5 mm, length 40 mm) were placed on both sides of the lumbar spine. The pull-out strength and the load-displacement ratio of screws in two different screw trajectories under up, down, left, right working conditions were analyzed, and the stability between the screw and vertebral body under osteoporotic conditions was evaluated. Results Compared with TT, the pull-out strength of MCBT screw was increased by 13.1%. Compared with PS, the load-displacement ratio of MCBT screw under up, down and left working conditions was increased by 57.2%, 32.4%, and 31.6%. Under right working condition, although the load-displacement ratio of MCBT screw was higher than that of PS, no statistical difference was found. The load-displacement ratio of vertebral body in MCBT group under lateral bending and axial rotation was significantly higher than that in TT group. The load-displacement ratio of vertebral body in MCBT group under flexion was lower than that in TT group. Although the load-displacement ratio of vertebral body in MCBT group under extension was higher that that in TT group, no statistical difference was found. Conclusions MCBT is superior to TT in pull-out strength, screw stability and vertebral body stability under lateral bending and axial rotation, but its vertebral body stability under flexion and extension was weaker than that of TT. The research findings demonstrate the superiority of MCBT under osteoporotic conditions and lay the foundation for clinical application of MCBT.

Relationship between vertebral vessels and cortical path screws in cortical transfixation / Relação dos vasos vertebrais com parafuso de trajeto cortical com transfixação da cortical / Relación de los vasos vertebrales con tornillo de trayectoria cortical con transfijación cortical

ABSTRACT Introduction: This study aims to evaluate the safety of using the cortical path screw with transfixation of the second cortical bone in relation to the vascular structures. Methods: This retrospective observational study (level of evidence: III, study of non-consecutive patients) analyzed data from the medical records of patients who underwent computed angiotomography scans of the abdomen at Hospital Mater Dei, measuring, in millimeters, the distance between the point of the lumbar vertebra considered the anatomical reference for the transfixation of the second cortical bone and the vascular structures adjacent to the spine (abdominal aorta, inferior vena cava, iliac vessels, segmental lumbar arteries). Results: Forty-eight patients were evaluated, with a mean age of 60 years (±8 years, 41-75), of whom 52% were male and 48% female. The measurements obtained between the pre-vertebral vessels and the possible screw exit points did not demonstrate contact in any of the vertebrae studied. Conclusions: The measurements obtained suggest the safety of using the cortical path screw transfixing the second cortical bone. Knowing the position of the vessels is essential to reduce intra- and postoperative complications related to spinal instrumentation. Level of evidence III; Study of non-consecutive patients.

RESUMO Introdução: Este trabalho objetiva avaliar a segurança do uso do parafuso de trajeto cortical com transfixação da segunda cortical óssea com relação às estruturas vasculares. Métodos: Estudo observacional retrospectivo (nível de evidência: III, estudo de pacientes não consecutivos) analisou dados de prontuários de pacientes submetidos ao exame de angiotomografia computadorizada do abdome no Hospital Mater Dei, realizando a medida, em milímetros, entre o ponto da vértebra lombar considerado a referência anatômica para a transfixação da segunda cortical óssea e as estruturas vasculares adjacentes à coluna (aorta abdominal, veia cava inferior, vasos ilíacos, artérias lombares segmentares). Resultados: Foram avaliados 48 pacientes, com média de idade de 60 anos (±8 anos, 41-75), sendo 52% do sexo masculino e 48% do feminino. As medidas obtidas entre os vasos pré-vertebrais e os pontos possíveis de saída do parafuso não demonstraram contato, em todas as vértebras estudadas. Conclusões: As medidas obtidas sugerem a segurança do uso do parafuso de trajeto cortical transfixando a segunda cortical óssea. Conhecer a posição dos vasos é essencial para reduzir as complicações intra e pós-operatórias relacionadas à instrumentação da coluna vertebral. Nível de evidência III; Estudo de pacientes não consecutivos.

RESUMEN Introducción: Este estudio tiene como objetivo evaluar la seguridad del uso del tornillo de trayectoria cortical con transfijación de la segunda cortical ósea con respecto a las estructuras vasculares. Métodos: Estudio observacional retrospectivo (nivel de evidencia: III, estudio de pacientes no consecutivos) que analizó datos de registros médicos de pacientes sometidos a examen de angiografía por tomografía computarizada de abdomen en el Hospital Mater Dei, realizando la medición, en milímetros, entre el punto de la vértebra lumbar considerado la referencia anatómica para la transfijación de la segunda cortical ósea y las estructuras vasculares adyacentes a la columna (aorta abdominal, vena cava inferior, vasos ilíacos, arterias lumbares segmentarias). Resultados: Se evaluaron 48 pacientes, con una edad promedio de 60 años (±8 años, 41-75); 52% eran hombres y 48% mujeres. Las medidas obtenidas entre los vasos prevertebrales y los posibles puntos de salida del tornillo no demostraron contacto en todas las vértebras estudiadas. Conclusiones: Las medidas obtenidas sugieren la seguridad de utilizar el tornillo de trayectoria cortical transfijando la segunda cortical ósea. Conocer la posición de los vasos es fundamental para reducir las complicaciones intra y postoperatorias relacionadas con la instrumentación espinal. Nivel de evidencia III; Estudio de pacientes no consecutivos.

Cortical bone modifications after radiotherapy: cortex porosity and osteonal changes evaluated over time

Abstract Aiming to evaluate cortical bone microarchitecture and osteonal morphology after irradiation, twelve male New Zealand rabbits were used. The animals were divided: control group (no radiation-NIr); and 3 irradiated groups, sacrificed after: 7 (Ir7d); 14 (Ir14d) and 21 (Ir21d) days. A single radiation dose of 30 Gy was used. Computed microtomography analyzed the cortical microarchitecture: cortical thickness (CtTh), bone volume (BV), total porosity (Ct.Po), intracortical porosity (CtPo-cl), channel/pore number (Po.N), fractal dimension (FD) and degree of anisotropy (Ct.DA). After scan, osteonal morphology was histologically assessed by means: area and perimeter of the osteons (O.Ar; O.p) and of the Haversian canals (C.Ar; C.p). Microtomographic analysis were performed by ANOVA, followed by Tukey and Dunnet tests. Osteon morphology analyses were performed by Kruskal-Wallis, and test Dunn's. Cortical thickness was significant difference (p<0.010) between the NIr and irradiated groups, with thicker cortex at Ir7d (1.15±0.09). The intracortical porosity revealed significant difference (p<0.001) between irradiated groups and NIr, with lower value for Ir7d (0.29±0.09). Bone volume was lower in Ir14d compared to control. Area and perimeter of the osteons were statistically different (p<0.0001) between NIr and Ir7d. Haversian canals also revealed lower values (p<0.0001) in Ir7d (80.57±9.3; 31.63±6.5) compared to NIr and irradiated groups. Cortical microarchitecture was affected by radiation, and the effects appear to be time-dependent, mostly regarding the osteons morphology at the initial days. Cortex structure in Ir21d revealed similarities to control suggesting that microarchitecture resembles normal condition after a period.

Resumo Com o objetivo de avaliar a microarquitetura óssea cortical e a morfologia dos osteons após irradiação, foram utilizados doze coelhos machos da Nova Zelândia. Os animais foram divididos: grupo controle (sem radiação-NIr); e 3 grupos irradiados, sacrificados após: 7 (Ir7d); 14 (Ir14d) e 21 (Ir21d) dias. Foi utilizada uma dose única de radiação de 30 Gy. A microtomografia computadorizada analisou a microarquitetura cortical: espessura cortical (CtTh), volume ósseo (BV), porosidade total (Ct.Po), porosidade intracortical (CtPo-cl), número de canal/ poro (Po.N), dimensão fractal (DF) e grau de anisotropia (Ct.DA). Após a varredura, a morfologia dos osteosn foi avaliada histologicamente por meio de: Área e perímetro do osteon (O.Ar; O.p) e dos canais de Havers (C.Ar; C.p). A análise microtomográfica foi realizada por ANOVA, seguida pelos testes de Tukey e Dunnet. As análises morfológicas do osteon foram realizadas por Kruskal-Wallis e testadas por Dunn. A espessura cortical foi diferente (p<0,010) entre os grupos controle e irradiados, com córtex mais espesso no Ir7d (1,15±0,09). A porosidade intracortical revelou diferenças significativas (p<0,001) entre os grupos irradiados e o controle, com menor valor para Ir7d (0,29±0,09). O volume ósseo foi menor no Ir14d em relação ao controle. Área e perímetro do osteon foi diferente (p<0,0001) entre o controle e Ir7d. Os canais haversianos também revelaram valores mais baixos (p<0,0001) em Ir7d (80.57±9.3; 31.63±6.5) em relação ao controle e demais grupos irradiados. A microarquitetura cortical é afetada pela radiação e os efeitos parecem ser dependentes do tempo, principalmente em relação à morfologia dos osteons nos dias iniciais. A estrutura cortical em Ir21d revelou semelhanças com o controle, sugerindo que a microarquitetura se assemelha à condição normal após um período.

The effects of casein kinase 2 interacting protein-1 on the growth and development of craniomaxillofacial soft and hard tissues in mice / 口腔疾病防治

Objective@# To investigate the effect of casein kinase 2 interacting protein-1 (CKIP-1) on craniofacial soft tissues and hard tissues, to provide the basis for the study and treatment of craniomaxillofacial related diseases.@*Methods@#6-month- old male CKIP-1 knockout (KO) mice were selected as the experimental group, and wild-type (WT) mice were selected as the control group. The craniomaxillofacial hard tissues (parietal bone, nasal bone, incisors and molars) were analyzed through micro- CT, and the morphological changes of maxillofacial soft tissues (nasal cartilage, lip mucosa and tongue) were analyzed through HE staining and toluidine blue staining.@* Results@#CKIP-1 negatively regulated bone mass of cancellous bone of cranial and maxillofacial bones and dentin mineralization. Compared with the WT mice, the thickness of the parietal baffle layer increased by 93% in KO mice, while cortical bone showed no significant difference between the two groups. The nasal cancellous bone thickness increased by 160% in KO-mice, while cortical bone showed no significant difference between the two groups; the enamel thickness was normal, but the pulp cavity became smaller and the dentin thickness increased by 48%. Compared with the WT mice, the HE staining and toluidine blue staining analyses of the soft tissues revealed that the thickness of the alar cartilage plate of KO mice increased by 57%, and local ossification was found within the cartilage plate. The thickness of the keratinized layer of the labial mucosa increased by 170% in KO mice and the muscle fiber diameter of the lingual muscle increased by 45%. @*Conclusion@#CKIP-1 genes have different effects on the growth and development of various soft and hard tissues in the maxillofacial region of mice.

Pressure side and tension side comminution of femoral neck cortex are independent risk factors for aseptic necrosis after femoral neck fracture surgery / 中国骨伤

OBJECTIVE@#To investigate the related factors of aseptic necrosis of femoral head after closed reduction and internal fixation of femoral neck fracture.@*METHODS@#From January 2009 to January 2016, 236 patients with femoral neck fracture were treated with closed reduction and internal fixation with 3 hollow lag screws, including 111 males and 125 females, aged from 19 to 89 (50.17±12.88) years. According to the follow-up results, the correlation of aseptic necrosis of femoral head was analyzed. Univariate analysis of age, gender, injured side, body weight, injury mechanism, preoperative waiting time, Garden classification and whether there was comminution of femoral neck cortex was conducted to obtain the independent variables with significant difference. Then binary logistic regression analysis was conducted to explore the independent risk factors of avascular necrosis of femoral head.@*RESULTS@#The average follow-up period of 236 cases was 4.58 years. There were significant differences in the range of injury (24.69% vs. 5.16%, @*CONCLUSION@#High energy injury, preoperative waiting time (>48 h) and comminution of femoral neck cortex were independent risk factors for aseptic necrosis of femoral head. In addition, cortical comminution on the pressure side and tension side of the femoral neck is a strong prognostic risk factor for aseptic necrosis of the femoral head, because it indicates a more serious and complex injury mechanism.

Parâmetros imaginológicos em pacientes com alteração de massa óssea / Imaginological parameters in patients with bone mass alteration

Os inibidores de aromatase (IAs) são medicamentos mais comumente utilizados para tratamento para pacientes com câncer de mama. Os IAs atuam inibindo a enzima aromatase, que é responsável pela conversão de hormônios esteroidais. Vários estudos mostram a importância do estrógeno para a formação óssea. Acredita-se que a privação do estrógeno possa ter um efeito deletério no osso causando o aumento da reabsorção óssea, diminuição da densidade mineral óssea (DMO) e com isso o aumento do risco de osteoporose e fraturas. A osteoporose é uma doença sistêmica multifatorial caracterizada pela redução da massa óssea e desorganização estrutural do tecido ósseo. O diagnóstico da osteoporose é baseado em critérios densitométricos da Organização Mundial de Saúde (OMS) com referência na classificação do T-score, realizada pela técnica de absorciometria de energia dupla de raios X (DXA), cujo valor avalia a DMO. Por se tratar de uma doença sistêmica, a osteoporose também afeta os ossos maxilares. Desta forma, o trabalho tem como objetivo avaliar parâmetros imaginológicos em pacientes mulheres que fazem tratamento com; IAs e encaminhadas para investigação de perda de massa óssea em um hospital de referência no tratamento dessas pacientes. Foram avaliadas 40 mulheres sob terapia com IAs. Foram avaliados índices radiomorfométricos (IR) de tomografia computadorizada de feixe cônico (TCFC) e análise fractal (AF) para algumas regiões de interesse (RI), espessura da cortical mandibular (ECM) e índice cortical mandibular (ICM) em radiografias panorâmicas digitais (RPD). Todas as pacientes foram submetidas ao exame DXA para avaliar a condição de DMO e divididas nos grupos: normal e baixa DMO. Para cada IR e para as RI da dimensão fractal, foram estabelecidas a curva característica de operação do receptor (ROC), a área sob a curva (AUC), a sensibilidade e a especificidade com seus receptivos intervalos de confiança. Os valores de AUC para os índices de RPD variaram de 52,6%-75,8%. O índice com a maior AUC foi a ECM, apresentando sensibilidade de 38,1%-100,0% e especificidade de 36,8%-84,2%. Para a AF, a RI do trabeculado total teve a maior sensibilidade, enquanto a RI anterior ao forame mentual teve a maior especificidade. Na análise da TCFC, os valores de AUC variaram de 51,8%-62,0%. Os índices com a AUC mais elevada foram o índice molar (M), com sensibilidade 18,1%-61,6% e especificidade de 66,9%-98,7% e o índice anterior (A) com sensibidade de 25,7%- 70,2% e especificidade de 48,8%-90,9%. O índice da sínfise (S) apresentou a maior sensibilidade e o índice posterior (P) apreentou a maior especificidade. Os índices de tomografia computadorizada inferior (ITC I) apresentou sensibilidade e especificidade razoáveis. Assim a ECM, a AF das RI do ângulo da mandíbula e do trabeculado total da RPD, bem como os índices ITC (I), M, P e A na TCFC mostraram-se úteis para identificar mulheres na pós-menopausa que usavam AI com baixa DMO.

Aromatase inhibitors (AIs) are the most commonly used drugs to treat breast cancer patients. AIs work by inhibiting the aromatase enzyme, which is responsible for converting steroid hormones. Several studies show the importance of estrogen for bone formation. It is believed that estrogen deprivation can have a deleterious effect on bone, causing increased bone resorption, decreased bone mineral density (BMD) and thus an increased risk of osteoporosis and fractures. Osteoporosis is a multifactorial systemic disease characterized by reduced bone mass and structural disorganization of bone tissue. The diagnosis of osteoporosis is based on densitometric criteria of the World Health Organization (WHO) with reference to the T- score classification, performed by the dual energy X-ray absorptiometry (DXA) technique, whose value assesses the BMD. As it is a systemic disease, osteoporosis also affects the maxillary bones. Thus, the study aims to evaluate imaging parameters in female patients undergoing treatment with AIs and referred for investigation of bone mass loss in a reference hospital in the treatment of these patients. Forty women undergoing therapy with AIs were evaluated. Radiomorphometric indices (RI) of cone beam computed tomography (CBCT) and fractal dimension (FD) were evaluated for some regions of interest (ROI), mandibular cortical width (MCW) and mandibular cortical index (MCI) in digital panoramic radiographs (DPR). All patients underwent the DXA exam to assess the status of BMD and divided into groups: normal and low BMD. The AUC values for the DPR indices ranged from 52.6%-75.8%. The index with the highest AUC was the mandibular cortical width ([MCW]; sensitivity: 38.1%-100.0%; specificity: 36.8%-84.2%). For FD, the total trabecular index had the greatest sensitivity, while the index anterior to the mental foramen (MF) had the highest specificity. In CBCT analysis, the values of AUC ranged from 51.8%-62.0%. The indices with the highest AUC were the molar index (M, sensitivity: 18.1%-61.6% and specificity: 66.9%-98.7%) and anterior (A, sensitivity: 25.7%-70.2% and specificity 48.8%-90.9%). The symphysis (S) index had the highest sensitivity, and the posterior (P) index presented the highest specificity. Sensitivity and specificity reasonable were obtained to computed tomography index (Inferior) [CTI (I)]. The MCW, FD of ROI of the mandible angle and total mandibular in the DPR, as well as the CTI (I), M, P, and A indices in the CBCT are useful to identify postmenopausal women who were using AI with low BMD.

Análise orofacial de indivíduos com Osteogênese Imperfeita: índices radiomorfométricos, dimensão fractal do osso mandibular e má oclusão / Orofacial analysis of individuals with Osteogenesis Imperfecta: radiomorphometric indices, fractal dimension of the mandibular bone and malocclusion

A Osteogênese Imperfeita (OI) é uma doença genética rara, caracterizada por ossos frágeis com fraturas recorrentes. Na maioria dos casos a OI, é causada por mutações nos genes COL1A1 ou COL1A2 os quais codificam o colágeno tipo I. Mutações em novos genes envolvidos na via do metabolismo ósseo têm sido descobertas. A OI está associada a alterações dentárias e craniofaciais, sendo as mais prevalentes a dentinogênese imperfeita e a má oclusão. A literatura tem mostrado que é possível predizer o risco de fratura óssea ao analisarmos índices radiomorfométricos e dimensão fractal (DF) da mandíbula em radiografias panorâmicas. O objetivo desta pesquisa foi verificar se há diferenças no padrão de oclusão, na cortical e no trabeculado ósseo mandibular de indivíduos com OI quando comparados com indivíduos sem OI. Desse modo, a tese conta com a apresentação de dois artigos científicos. O primeiro artigo objetivou analisar dois índices radiomorfométricos, o índice cortical mandibular (ICM) e o índice mentual (IM), e a DF do trabeculado ósseo mandibular de indivíduos com OI e comparar com indivíduos sem OI. Foi realizado um estudo transversal, pareado por idade e sexo, com 20 indivíduos com OI e 40 sem OI. Os dados foram obtidos por meio de radiografias panorâmicas de pacientes com OI e sem OI atendidos na Faculdade de Odontologia da Universidade Federal de Minas Gerais. O estudo foi aprovado pelo Comitê de Ética em Pesquisa da UFMG (protocolo 02470518.3.0000.5149). O teste t pareado (p <0,05) foi usado para comparar os valores de IM e DF. O teste do qui-quadrado (p <0,05) comparou o ICM entre os grupos. A média de idade de ambos os grupos foi 13,10 anos (± 6,57). O valor médio do IM foi de 2.08 (±0.79) no grupo de indivíduos com OI e 2.91 (±0.60) para indivíduos sem OI (p<0,001). O valor médio de DF do grupo OI [0.3248 (±0.7240)] foi inferior ao do grupo sem OI [0.3814 (±0.5587)] no côndilo mandibular (p=0,002). O grau C3 do ICM foi mais frequente entre os indivíduos com OI (p <0,001). Indivíduos com OI apresentaram valores menores nos IM e DF, além de pior morfologia da cortical mandibular. O segundo artigo, uma revisão sistemática e meta-análise (já publicada), objetivou avaliar se indivíduos com OI são mais afetados por má oclusão do que indivíduos normotípicos. Foi realizada uma busca nas principais bases. A avaliação do risco de viés e a análise da força de evidência foram conduzidas. Em comparação com indivíduos sem OI, o grupo com OI teve 19,69 vezes mais chance de apresentar má oclusão de Classe III de Angle (OR = 19,69, IC: 9,00­43,09) e apresentar maior mordida cruzada anterior (MD = 6,08, CI: 2,40­9,77). Indivíduos sem OI tiveram um ângulo ANB (MD= 3,88, IC: 1,15­6,61) e ângulo SNA (MD = 2,11, IC: 0,24­3,98) significativamente maiores em comparação com indivíduos com OI. Nenhuma diferença entre os grupos foi encontrada para SNB (MD = −0,50, IC: −2,21 a 1,21) e mordida aberta (MD = 0,98, IC: −0,29 a 2,25). A maioria dos estudos incluídos teve qualidade metodológica moderada. A força da evidência foi baixa ou muito baixa. A ocorrência de má oclusão Classe III de Angle e mordida cruzada anterior foi maior entre os indivíduos com OI em comparação com aqueles sem OI.

Osteogenesis Imperfecta (OI) is a rare genetic disease characterized by fragile bones with recurrent fractures. In most cases, OI is caused by mutations in the COL1A1 or COL1A2 genes which encode type I collagen. Mutations in new genes involved in the bone metabolism pathway have been discovered. OI is associated with dental and craniofacial alterations, the most prevalent being dentinogenesis imperfecta and malocclusion. The literature has shown that it is possible to predict the risk of bone fracture when analyzing radiomorphometric indices and fractal dimension (FD) of the mandible in panoramic radiographs. The objective of this research was to verify if there are differences in the occlusion pattern, in the cortical and in the mandibular bone trabeculate of individuals with OI when compared to individuals without OI. Thus, the thesis has the presentation of two scientific articles. The first article aimed to analyze two radiomorphometric indices, the mandibular cortical index (MCI) and the mentual index (MI), and the FD of the mandibular bone trabeculate of individuals with OI and compare with individuals without OI. A cross-sectional study, matched by age and sex, was carried out with 20 individuals with OI and 40 without OI. Data were obtained through panoramic radiographs of patients with OI and without OI treated at the Faculty of Dentistry of the Federal University of Minas Gerais. The study was approved by the Research Ethics Committee at UFMG (protocol 02470518.3.0000.5149). Paired t-test (p < 0.05) was used to compare MI and DF values. The chi-square test (p < 0.05) compared the ICM between groups. The mean age of both groups was 13.10 years (± 6.57). The mean value of MI was 2.08 (±0.79) in the group of individuals with OI and 2.91 (±0.60) for individuals without OI (p<0.001). The mean FD value of the OI group [0.3248 (±0.7240)] was lower than that of the group without OI [0.3814 (±0.5587)] in the mandibular condyle (p=0.002). ICM grade C3 was more frequent among individuals with OI (p<0.001). Individuals with OI had lower MI and DF values, in addition to worse mandibular cortical morphology. The second article, a systematic review and meta-analysis (already published), aimed to assess whether individuals with OI are more affected by malocclusion than normotypic individuals. A search was carried out in the main bases. Risk of bias assessment and strength of evidence analysis were conducted. Compared with individuals without OI, the group with OI was 19.69 times more likely to have Angle Class III malocclusion (OR = 19.69, CI: 9.00­ 43.09) and to have greater anterior crossbite (MD = 6.08, CI: 2.40­9.77). Subjects without OI had a significantly greater ANB angle (MD= 3.88, CI: 1.15­6.61) and SNA angle (MD= 2.11, CI: 0.24­3.98) compared to subjects with hi. No difference between groups was found for SNB (MD = −0.50, CI: −2.21 to 1.21) and open bite (MD = 0.98, CI: −0.29 to 2.25). Most of the included studies were of moderate methodological quality. The strength of the evidence was low or very low. The occurrence of Angle Class III malocclusion and anterior crossbite was higher among individuals with OI compared to those without OI.

Mechanical properties of rat tibia under high-G environment / 中国组织工程研究

BACKGROUND: With the development of Chinese space industry, pilots are exposed to high-G mechanical environment, which will seriously affect their bones. However, as one of the bones that are most prone to fracture, the biomechanical behavior of the tibia under extreme mechanical environment is rarely reported. OBJECTIVE: To explore the effects of different high-G mechanical environments on the rat growth and development and the mechanical properties of the tibia. METHODS: Male Wistar rats were provided by Laboratory Animal Center of Academy of Military Sciences. The cantilever was set to run at different speeds and accelerations with a high-G centrifugal loading device, and the high-G rat model was made. The rats were weighed weekly. The left tibia of rats was used for undergoing a three-point bending experiment, and the deflection and elastic modulus of the tibia were calculated. The right tibia was subjected to a creep test, and constant stress was applied on the surface of tibial cortical bone and kept 3 600 seconds, so as to observe the changes of creep strain. The study was approved by the Laboratory Animal Ethical Committee of Tianjin University of Technology. RESULTS AND CONCLUSION: The high-G environment affected the normal growth and development of rats, inhibited weight gain and reduced the mechanical properties of the tibia, and reduced the limit deflection of the tibia by 8.1%, 12.2%, 37.8%, and 51.4%, respectively. Limit loads were decreased by 16%, 9%, 25.2%, and 29% respectively. To conclude, extremely high-G environment exerts serious negative effects on rats.

Autologous cortical bone block for repair of implant-site jaw bone defects / 中国组织工程研究

BACKGROUND: Autologous bone with good biocompatibility possesses the characteristics of bone conduction, osteoinduction and osteogenesis. However, the healing process after autologous bone grafting is still controversial. The focus of controversy is whether the bone graft is completely absorbed and replaced or whether it can retain cell viability for a long time. OBJECTIVE: To observe the histological changes in bone remodeling and regeneration after cortical bone grafting. METHODS: Six healthy beagle dogs were selected as the research animals. The maxillary premolars of experimental dogs were extracted and the bone plates with width of 10 mm, length of 15 mm and thickness of 2 mm were removed from the buccal side. A bone defect model was established. The corresponding size of cortical bone block was cut on the buccal side of the bilateral mandibular body. Cortical bone grafts were fixed in the maxillary defect area. On one side pure cortical bone block was used as grafting material; on the other side the implant was placed simultaneously with the bone graft. Samples were harvested at 3 and 6 months after bone grafting. The cell survival and bone graft resorption of autologous cortical bone graft were analyzed by gross observation and histological observation. The study protocol was approved by the Animal Ethics Committee of Dalian Medical University, China. RESULTS AND CONCLUSION: The size of the grafted bone was gradually reduced, and the margin was blunt and firmly bonded to the base bone. All implants lost after 6 months. A newly formed connection between the graft and the base bone was shown by hard tissue ground sections. The porosity of bone lacuna in the grafted bone block at 6 months was significantly lower than that at 3 months (P < 0.05). The grafted bone resorption rate at 6 months was significantly higher than that at 3 months (P < 0.05). These findings indicate that osseointegration exists between grafted cortical bone block and the base bone of the recipient area. Osteocytes in the graft bone partially remain alive. With the prolongation of healing period, the proportion of new bone cells increases, and the volume of the grafted bone gradually decreases. Osseointegration of the concurrent implant is disturbed due to the absorption of cortical bone graft.

Mechanical stability of the fracture at the junction of lumbar vertebral body and pedicle after implantation with different diameters of pedicle screws / 中国组织工程研究

BACKGROUND: Most scholars believe that the fracture of the lumbar spine and pedicle is stable, and transvertebral pedicle screw implantation can improve the stability of fractures. However, the diameter of the transvertebral pedicle screw, mechanical stability and safety of the vertebrae still remain controversial. OBJECTIVE: To analyze the effect of pedicle screws of different diameters and pedicle cortex on the mechanical stability of the fractured vertebrae and pedicle by three-dimensional finite element method. METHODS: Based on normal adult L2-L3 CT DICOM data, a mimics software was used to establish a model of the fracture at L2 vertebral body and the pedicle. At the same time, a three-dimensional model of L3 vertebra was created. The L2-L3 model was imported into 3-matic in stl format, and a model of pedicle screws with different diameters (diameter of 6.5 and 6.0 mm, and length of 45 mm) was established. The model was imported into ansys after the material attributes were assigned in the mimics software. A vertical load of 500 N was applied to the upper surface of the L2 vertebral body to simulate the biomechanical performance of a adult with standard body mass after implantation with transvertebral pedicle screw with different diameters under upright condition. RESULTS AND CONCLUSION: (1) After implantation with 6.0 mm screw, the equivalent load on the lower, upper, inner, and outer walls of the pedicle at the junction of the lumbar vertebra and the pedicle was (1.28±0.62), (0.95±0.18), (0.62±0.37), and (0.36±0.16) MPa, respectively. The difference was significant among groups (F=4.298, P < 0.05). (2) After implantation with 6.5 mm screw, the equivalent load on the lower, upper, inner, and outer walls of the pedicle at the junction of the lumbar vertebra and the pedicle was (1.82±0.76), (1.11±0.18), (0.93±0.38), and (0.43±0.14) MPa, respectively. The difference was significant among groups (F=7.034, P < 0.05). (3) The equivalent load on the lower, upper, inner, and outer walls of the 6.5 mm pedicle screw model was significantly higher than that on the 6.0 mm pedicle screw model (P < 0.05). (4) These results imply that the larger the pedicle screw is, the greater the load on the cortical bone at the junction of the lumbar vertebra and the pedicle is, and the stronger the holding force is. The load on the upper, lower, inner and outer walls of the pedicle is positively related to its cortical thickness. The cortical bone of the inferior wall is thickest, the equivalent load it bears is largest, and the cortical bone of the outer wall is thinnest, and it has the smallest equivalent load. The closer the pedicle screw is to the lower medial wall within the pedicle, the stronger the holding force and the better the stability. The closer it is to the upper and outer side walls, the smaller the gripping force and the worse the stability. However, the placement of nails on the upper and outer walls is safer than the placement of nails on the lower inner wall, and the pros and cons need to be weighed in accordance with the experience of the surgeon during placement.

Correlation of cortical bone thickness and x-ray gray value in different planes of proximal femur with brittle fracture of female hip / 中国组织工程研究

BACKGROUND: With the aging of population, brittle fracture diseases have attracted more and more attention from clinicians. Bone mineral density detection cannot meet the risk assessment of brittle fracture. As one of the new directions and methods to evaluate the risk of brittle fracture, cortical thickness has been studied and discussed by more and more scholars. OBJECTIVE: To explore the correlation of bone cortical thickness values and X-ray gray values in different planes of proximal femur with hip brittle fracture in women aged over 50 years old under X-ray DR photography, so as to evaluate the most appropriate measurement plane for predicting the risk of hip brittle fracture in women among different planes of proximal femur. METHODS: According to the inclusion criteria, relevant clinical data of 100 female patients aged over 50 years old who underwent X-ray DR pelvic radiograph examination at Department of Radiology of the Ninth Affiliated Hospital of Guangxi Medical University from July 2018 to June 2019 were collected. All patients signed the informed consents and the study was approved by the ethics committee of the hospital. The measurement planes of cortical thickness of the proximal femur were designed to be the middle part of femoral neck, within 1 cm above the lesser trochanter, and within 1 cm below the lesser trochanter, with a total of three groups of measurement planes. The gray value of X-ray was measured by taking the line between the middle point of the great rotor and the small rotor as the rectangular diagonal line to take the rectangular area for measurement. RESULTS AND CONCLUSION: (1) Women aged 50-64 years were as group A (n=50) and those aged 65 years and older were as group B (n=50). (2) The cortical thickness and X-ray gray value within 1 cm below the lesser trochanter, and within 1 cm above the lesser trochanter in the group B were significantly lower than those in the group A; fracture rate was higher in group A than in group B (P 0.05). (3) On the whole, cortical thickness values were highest in the within 1 cm below the lesser trochanter, followed by within 1 cm above the lesser trochanter and lowest in the middle part of the femoral neck (P 0.05). (5) The difference of cortical thickness within 1 cm below the lesser trochanter and within 1 cm above the lesser trochanter between fracture and non-fracture groups in the group A was significant (P 0.05). At the age above 50 years, the difference of cortical thickness and X-ray gray value in each measured plane between fracture and the non-fracture groups was significant (P < 0.05). (6) To conclude, the cortical thickness becomes thinner and the gray value of X-ray becomes smaller, and the possibility of brittle fracture of hip becomes higher. When assessing the risk of hip fracture in women aged over 50 years using cortical thickness of the proximal femur, measurement within 1 cm below the lesser trochanter is recommended.

Simulation accuracy of cortical bone fracture based on different types of strain criterion / 中国组织工程研究

BACKGROUND: Cortical bone crack caused by accident or other external factors is one of the main causes of fracture, so the mechanism of crack formation and propagation for cortical bone under different loads should be understood primarily to avoid fracture. Bone specimens may be destructed in experiments, which can lead to a difficulty to observe the interior mechanical state of bone structure before and after fracture. Therefore, it is important to find a finite element method that can accurately simulate the processes of cortical bone crack formation, propagation, and fracture. Current simulations mainly use the principal strain or the equivalent strain to determine the mechanical state of the element in the finite element model and to perform fracture simulation, but there are few studies on the simulation accuracy when using these two types of strains. OBJECTIVE: To testify the simulation accuracy of cortical bone fracture with the principal strain and the equivalent strain. METHODS: The principal strain and the equivalent strain were applied to perform the three-point bending simulation, and the simulation results were compared with the experimental results to determine which strain was more accurate. RESULTS AND CONCLUSION: (1) The failure time of the cortical bone simulated by the principal strain was significantly later than that obtained by the equivalent strain. (2) Compared with the experimental results, it was found that the simulation results obtained by equivalent strain were closer to the experimental results. (3) Therefore, simulating cortical bone crack and fracture using the equivalent strain is accurate.

Application of the tent bone augmentation technique in dental implants / 口腔疾病防治

@#Tent bone augmentation technology, including the tenting screw technique, autogenous cortical bone tenting technique and implant tent-pole technique, has recently been considered as a type of bone augmentation method to solve serious alveolar bone deficiency. The tenting screw technique is simple to perform and widely used in clinical practice; it can effectively increase bone in both horizontal and vertical directions in local bone defect areas with fewer complications than other techniques. The autogenous cortical bone tenting technique is mainly used for bone augmentation in large bone defect areas. The operation is relatively simple, but it needs to be combined with partial autogenous bone grafting, with high technical sensitivity and complications. The implant tent-pole technique is the most complex method and is mainly used for bone augmentation in severe alveolar ridge absorption areas of the mandible. The maximum vertical bone augmentation height can be obtained by combining this method with autogenous bone grafting, and the number of postoperative complications is relatively high. This article reviews recent research on the application of this technique to repair various alveolar bone defects in order to provide reference for clinical implant treatment.

Application of three-dimensional reconstruction simulation to define the starting point of lumbar cortical bone trajectory / 中国修复重建外科杂志

Objective: CT three-dimensional reconstruction technology was used to simulate the placement of the lumbar cortical bone trajectory (CBT), to determine the starting point and direction of the screw trajectory. Methods: Between February 2017 and April 2018, 24 patients with lumbar CT were selected as the study object. There were 7 males and 17 females, with an average age of 50.4 years (range, 37-68 years). The CT DICOM data of patients were imported into Mimics 16.0 software, and the three-dimensional model of lumbar spine was established. A 5 mm diameter cylinder was set up to simulate the CBT by using Mimics 16.0 software. According to the different implant schemes, the study was divided into groups A, B, and C, the track of the screw respectively passed through the upper edge, the medial edge, and the lower edge of the isthmus of the pedicle. The intersection of simulated screw and lumbar spine was marked as region of interest (ROI) and a mask was generated. The average CT value [Hounsfield unit (HU)] and the screw length of ROI were automatically measured by Mimics 16.0 software. In addition, the head inclination angle and head camber angle of the screw were measured respectively. Point F was the intersection of the level of the lowest edge of the transverse process and the lumbar isthmus periphery. The horizontal and vertical distance between point F and the starting point were measured, and the relationship between the three schemes and the position of the zygapophysial joint and spinous process was observed. Results: Plan A has the highest ROI average HU, with the maximum value appearing in L 4; plan B has the longest screw length, with the maximum value appearing in L 5; plan C has the largest nail track head inclination angle, with the maximum value appearing in L 4; plan B has the largest nail track head camber angle, with the maximum value appearing in L 3. The screw length and head camber angle of the nail in group B were significantly greater than those in groups A and C ( P0.05). In plan A, 74.48% (143/192) screws had a horizontal distance of -2 to 4 mm from point F, a vertical distance of 6-14 mm from point F, a head inclination angle of (14.64±2.77)°, and a head camber angle of (6.55±2.09)°, respectively; in plan B, 84.58% (203/240) screws had a horizontal distance of 1-6 mm from point F, a vertical distance of 1-5 mm from point F, a head inclination angle of (26.93±2.21)°, and a head camber angle of (10.29±2.46)°, respectively; in plan C, 85.94% (165/192) screws had a horizontal distance of -2 to 3 mm from point F, a vertical distance of -2 to 4 mm from point F, a head inclination angle of (33.50±3.69)°, and a head camber angle of (6.47±2.48)°, respectively. Conclusion: Plan B should be selected as the starting point of the L 1-L 5 CBT implant. It is located at the intersection of the lowest horizontal line of the transverse process root and the lateral edge of the lumbar isthmus, which is 1-6 mm horizontally inward, 1-5 mm vertically upward, with a head inclination angle of (26.93±2.21)°, and a head camber angle of (10.29±2.46)°, respectively.