Thickness Of Cancellous Bone Research Articles

A cross-sectional study of the anatomy of the jaws of a central-European caucasian population using cone beam computer tomography as a prerequisite for designing pre-formed calcium phosphate cement scaffolds

PurposeThis study aims to measure the cortical and cancellous bone thickness in the upper and lower jaws, serving as a data template for developing pre-defined calcium phosphate cement primary implant forms. These measurements are crucial for creating a biphasic scaffold. MethodsForty complete jaws were assessed for cortical bone shape and thickness using statistical analysis and specific software tools. Sex and age were considered, and four groups were created. ResultsThe cumulative thickness of the cortical layer varied from region to region. In both the upper and lower jaws, the cortical layer in the molar region was significantly thicker than in the frontal region. Within the alveolar process, cortical thickness increases with distance from the alveolar crest on both sides. The oral side of the lower jaw is significantly thicker than the vestibular side. For the upper jaw, no significant differences between the oral and vestibular sides were found in this study. Additionally, it is noteworthy that men have a significantly thicker cortical layer than women. Regarding age, no significant overall differences were found. ConclusionMathematical analysis of anatomical forms using polynomial functions improves understanding of jaw anatomy. This approach facilitates the design of patient-specific scaffold structures, minimizing the need for costly and time-consuming planning and enabling more efficient implementation of optimal therapy.

Effect of ultrasound attenuation on piezoelectric signal generation in cancellous bone

The piezoelectric signals generated in cancellous bone by ultrasound irradiation were numerically simulated using a piezoelectric finite-difference time-domain method. The changes of the piezoelectric signals with the cancellous bone thickness were investigated with the changes of the transmitted ultrasound signals. In the ultrasound direction of the strong trabecular orientation, two piezoelectric signals could be observed and was associated with the fast and slow waves in the ultrasound signal. The former wave amplitude did not vary with the thickness. The later wave amplitude randomly varied, but not significantly. In the ultrasound direction of the weak trabecular orientation, the piezoelectric signal due to the overlapped fast and slow waves and its multiple reflected wave could be observed. The former wave amplitude did not vary with the thickness. In both ultrasound directions, the local piezoelectric signal generated at the shallow depth of cancellous bone was dominant, which was because of the high ultrasound attenuation.

Multidimensional tooth movement boundaries in the extended aesthetic zone: a cone-beam computed tomography study

Abstract Purpose To establish tooth movement boundaries in four directions by a novel morphometric analysis of alveolar bone using conebeam computed tomography (CBCT) images. The aim was to assist clinicians in minimising the occurrence of bone fenestration and dehiscence, thereby facilitating safe and efficient orthodontic treatment. Methods CBCT images of 123 male volunteers comprising 55 individuals with hypodivergent vertical skeletal patterns and 68 individuals with normodivergent vertical skeletal patterns and normal occlusions but without a history of previous orthodontic treatment, were analysed. The mesiodistal and labiolingual alveolar bone height (ABH) as well as the labiolingual cancellous bone thickness (CBT) were measured in relation to the maxillary and mandibular anterior teeth and premolars. These parameters were subsequently compared between the different vertical skeletal patterns. Results Teeth within the extended aesthetic zone exhibited a limited range of safe movement on the labial aspect across all three root aspects, with 97.6% of the upper lateral incisors and 98.4% of the lower lateral incisors positioned against the labial cortical plate (<0.5 mm). The lingual aspects had significantly more space for tooth movement compared with the labial aspects (P < 0.05). The ABH was significantly greater in the hypodivergent group than the normodivergent group involving particular teeth and sites in the maxilla (P < 0.05), while no significant difference was noted in the mandible. The hypodivergent group also exhibited thicker cancellous bone on most labial and some lingual aspects. Conclusions The findings provided the average tooth movement range in the horizontal and vertical directions within the extended aesthetic zone in male individuals presenting with a normal occlusion. It was concluded that a hypodivergent growth pattern may have a relatively large range of safe tooth movement in the sagittal and vertical directions.

Three-dimensional evaluation of the cortical and cancellous bone density and thickness for miniscrew insertion: a CBCT study of interradicular area of adults with different facial growth pattern

AimThe purpose of this study was to evaluate the effect of the density and the thickness of the cortical and the cancellous bone at selected inter-radicular areas in subjects with different facial growth patterns using cone beam computed tomography (CBCT) in order to choose the optimal area for miniscrew insertion.Materials and methodsFrom 150 CBCT scans, 45 scans were included in the study. The subjects were categorized into three groups based on their skeletal growth pattern according to SN-GoMe angle and facial height index. Cortical and cancellous bone density and thickness were measured at the selected inter-radicular areas.ResultsCompared to the other two groups, the hyperdivergent group had thinner cortical bone in the anterior region of the maxilla between the central and the lateral incisors on the buccal side at 4 mm from the alveolar crest (P-value: 0.012) and on the palatal side at 7 mm from the alveolar crest (P-value: 0.030). Cancellous bone density values in these areas were higher in subjects with hypodivergent and hyperdivergent growth pattern. Furthermore, in hyperdivergent group less dense cortical bone in the posterior region of the maxilla on the palatal side between the second premolar and the first molar (p-value: 0.020) and on the buccal side between the first molar and the second molar (p-value: 0.038 & 0.047) was observed. No significant differences were found in the mandible between the three groups. No significant differences were found between the male and the female subjects.ConclusionHyperdivegents presented thinner cortical bone in the anterior of the maxilla between the central and the lateral incisors. Less dense cortical bone was found between maxillary second premolar and first molar on the palatal side and also between the maxillary first molar and the second molar on the buccal side in this group too. Normal showed higher density values in the posterior of the maxilla compared to the other two groups. No significant differences were found among three groups in mandible.

Reliability of Grayscale Value for Bone Density Determination in Oral Rehabilitation using Dental Implants.

Quality and quantity of jaw bones have been previously classified in literature using different methods. Imaging modalities such as computed tomography (CT), successfully determine bone density of jaws. This study aims to establish the role of cone-beam CT (CBCT) in determining the density of cortical and cancellous bones at different jaw sites. Eighty-three possible implant sites in healthy patients were evaluated using NewTomGiano CBCT machine. Cross-sections were obtained and cortical and cancellous bone densities on different aspects of the virtual implant in terms of Hounsfield unit (HU) were determined using New Net Technologies software version 6.1 and were classified according to software from D1 to D4. Data were entered into SPSS software (version 19.0) and were statistically analyzed. The mean HU showed the highest value for cortical and cancellous in the anterior mandible (mean HU 1874.01 and 1131.73, respectively) followed by the posterior mandible (mean HU 1789.20 and 872.95, respectively) and least in posterior maxilla (mean HU 1068.26 and 830.04, respectively). Maximum D1 bone type was found in cortical bone and D2 bone type was noted in cancellous bone area. Males showed very highly significant cortical bone thickness (P < 0.001) whereas females showed more cancellous bone thickness but the results were nonsignificant. A high degree of concordance between different regions of jaw bones with a strong correlation between the four bone types was obtained. Bone density plays a pivotal role in determining the prognosis of the implant. CBCT has proven to be beneficial in bone density analysis.

Retrospective study on the relationship between alveolar-bone morphology at the mandibular incisors and their inclination in adults with low-angle, skeletal class III malocclusion

Background and Aim: The orthodontic tooth movements should be such that the tooth moves safely within the alveolar bone. The alveolar bone around the mandibular central incisors of patients with skeletal class I and II malocclusion is thicker in comparison to those with skeletal class III malocclusion. The present study aimed to investigate an association between low angle inclination skeletal class-III malocclusion and the alveolar bone morphology around it. Materials and Methods: A retrospective study was carried out on 75 malocclusion patients in the Orthodontics Department of a Tertiary Care Hospital of Islamabad, Pakistan from January 2020 to December 2022. The malocclusions were confirmed in the patients via cone beam computed tomography (CBCT) imaging. The low angle, skeletal class III malocclusions were categorized into three different groups: Group-I (lingual-inclination), Group-II (upright), and Group-III (labial-inclination). Outcomes such as height of alveolar bone and area of cortical as well as cancellous thickness were determined independently on each side. Results: The labial cancellous bone thickness, thickness of labial cortical bone, alveolar bone total thickness, labial alveolar bone total area, and labial alveolar bone height were highest in group-III (labial-inclination). There was a positive correlation between mandibular central incisors and other aforementioned variables.

Structural Mechanical Properties of 3D Printing Biomimetic Bone Replacement Materials

One of the primary challenges in developing bone substitutes is to create scaffolds with mechanical properties that closely mimic those of regenerated tissue. Scaffolds that mimic the structure of natural cancellous bone are believed to have better environmental adaptability. In this study, we used the porosity and thickness of pig cancellous bone as biomimetic design parameters, and porosity and structural shape as differential indicators, to design a biomimetic bone beam scaffold. The mechanical properties of the designed bone beam model were tested using the finite element method (FEM). PCL/β-TCP porous scaffolds were prepared using the FDM method, and their mechanical properties were tested. The FEM simulation results were compared and validated, and the effects of porosity and pore shape on the mechanical properties were analyzed. The results of this study indicate that the PCL/β-TCP scaffold, prepared using FDM 3D printing technology for cancellous bone tissue engineering, has excellent integrity and stability. Predicting the structural stability using FEM is effective. The triangle pore structure has the most stability in both simulations and tests, followed by the rectangle and honeycomb shapes, and the diamond structure has the worst stability. Therefore, adjusting the porosity and pore shape can change the mechanical properties of the composite scaffold to meet the mechanical requirements of customized tissue engineering.

Evaluation of palate-related factors of the effectiveness of microimplant-assisted rapid palatal expansion in late adolescents and adults.

This study investigated the factors of the effectiveness of microimplant-assisted rapid palatal expansion (MARPE) in late adolescents and adults, such as age, midpalatal suture maturation (MPSM) stage, palate length (PL), palatal index (PI), and midpalatal bone thickness (MBT), and at each microimplant position, the palate bone thickness (PBT), the nasal cortical bone thickness (CoTN), the cancellous bone thickness (CaT), and the palate cortical bone thickness (CoTP) were evaluated. Cone-beam computed tomography (CBCT) images of 50 patients (mean, 23.30 ± 7.03years; range, 16-51years) treated with MARPE were evaluated. Maxillary expansion ratio (MER) was used to assess the MARPE effectiveness and grouped patients into low and high MER groups according to the mean of MER. MER was the ratio of maxillary expansion width to MARPE screw expansion measured in CBCT images. Thet-test was used to analyze the differences between the low and high MER groups. The Pearson correlation test was performed to investigate the correlation between MER and age, MPSM stage, PL, PI, MBT, PBT, CoTN, CaT, and CoTP. Age, MPSM stage, and MBT in regions 18mm and 21mm behind the incisor foramen correlated negatively with MER ([Formula: see text], - 0.390, - 0.386, and - 0.335, respectively, all [Formula: see text]), whereas PBT and CoTN of anterior microimplant positions correlated positively with MER ([Formula: see text] and 0.418, respectively, all [Formula: see text]). No correlation was observed between other variables and MER. MARPE effectiveness decreased as age and midpalatal suture maturation stage increased, respectively. Thinner midpalatal suture bone in regions 18mm and 21mm behind the incisor foramen, thicker palate bone, and nasal cortical bone of anterior microimplant positions were related to more effective MARPE. In patients with older chronological age and later MPSM stages, MARPE effectiveness might be unsatisfactory. Clinicians should carefully evaluate the palate bone thickness before MARPE treatment.

Correlation between mandibular anatomy and bad split occurrence during bilateral sagittal split osteotomy: a three-dimensional study.

This study aimed to find out the correlation between different anatomical parameters of the mandible and the occurrence of a bad split in patients who had undergone bilateral split sagittal ramus osteotomy (BSSRO). At both the distal roots of the first molar (1) and the retromolar area (2), we measured the distance from the buccal margin of the inferior dental canal (IDC) to the buccal margin of the cortical bone (MCBC), the thickness of both buccal cortical (WBCB) and cancellous bone (WBCA), distance from the superior border of IDC to the alveolar crest (MCAC), buccolingual thickness (BLT), and thickness of cancellous bone (WCA). At the ramus, the distances between the sigmoid notch to the upper part of the lingula (SL) and the inferior border of the mandible (SIBM), the thickness of the ramus at the level of the lingula (BLTR), and the anteroposterior width of the ramus (APWR) were measured. The paired and independent t-tests were used when applicable, and a P-value < 0.05 was considered significant. MCBC1 showed a significant difference between bad and non-bad split sides (P = 0.037). Both WBCA1 and WBCA2 show the same significant difference (P = 0.023, 0.024). Similarly, WCA1 and WCA2 showed a statistical difference between the bad and non-bad split sides (P = 0.027, 0.036). There were no statistically significant differences between the compared sides of WBCB1, WBCB2, MCAC1, MCAC2, SIBM, APWR, SL, and BLTR. Narrow space between IDC and the buccal cortical margin, along with the decrease in the thickness of both buccal cancellous bone and total cancellous bone at the inferior border of the mandible along the course of SSRO, has been implicated in the occurrence of bad split intraoperatively.

Sex differences in appropriate insertion depth for intraosseous access in adults: An exploratory radiologic single-center study.

Intraosseous access is a recommended alternative to venous access in emergencies. For its application, knowledge of the correct insertion depth is indispensable. We aimed to determine sex-specific differences on the appropriate insertion depth for intraosseous access in adults at the insertion sites most frequently used, namely the proximal and distal tibia and the proximal humerus. In this exploratory retrospective study, we measured thickness of soft tissue cover, cortex and cancellous bone along the puncture line on magnetic resonance images or computed tomography scans. Inclusion criteria were both sexes, 18-90 years of age and appropriate image quality. Primary outcome was the appropriate insertion depth to reach the cancellous bone for each sex. This was defined as the corridor between (i) the sum of the soft tissue cover and the cortex and (ii) the sum of (i) plus the diameter of the cancellous bone. Secondary outcomes were the differences in thickness of each layer between sexes. In 179 females and males, the appropriate insertion depth was 32.5-45.5 mm and 20.5-42.0 mm in the proximal tibia, 14.5-30.5 mm and 16.5-34.5 mm in the distal tibia, and 27.5-52.5 mm and 26.0-56.5 mm in the proximal humerus. Although females had a thicker soft tissue cover (+6.8 mm [95% CI 3.7-10.1], p < 0.01) in the proximal tibia, extrapolation by correlation analysis showed no clinically relevant difference between the sexes. In adults, there are no sex-specific differences in the appropriate insertion depth for intraosseous access in the proximal or distal tibia or in the proximal humerus.

Intermittent parathyroid hormone treatment affects the bone structural parameters and mechanical strength of the femoral neck after ovariectomy-induced osteoporosis in rats

BackgroundMenopause-induced decline in estrogen levels in women is a main factor leading to osteoporosis. The objective of this study was to investigate the effect of intermittent parathyroid hormone (PTH) on bone structural parameters of the femoral neck in ovariectomized rats, in addition to correlations of maximum fracture force.MethodsFifteen female Wister rats were divided into three groups: (1) control group; (2) ovariectomized (OVX) group; and (3) OVX + PTH group. All rats were then killed and the femurs extracted for microcomputed tomography scanning to measure volumetric bone mineral density (vBMD) and bone structural parameters of the femoral neck. Furthermore, the fracture forces of femoral neck were measured using a material testing system.ResultsCompared with the control and OVX + PTH groups, the OVX group had significantly lower aBMD, bone parameter, and mechanical strength values. A comparison between OVX and OVX + PTH groups indicated that PTH treatment increased several bone parameters. However, the OVX + PTH groups did not significantly differ with the control group with respect to the bone structural parameters, except for trabecular bone thickness of cancellous bone, which was greater. In addition, among the bone structural parameters, the CSA and BSI of cortical bone were significantly correlated with the maximum fracture force of the femoral neck, with correlations of, respectively, 0.682 (p = 0.005) and 0.700 (p = 0.004).ConclusionIntermittent PTH helped treat ovariectomy-induced osteoporosis of cancellous bone and cortical bone in the femoral necks of rats. The ability of the femoral neck to resist fracture was highly correlated with the two parameters, namely cross-sectional area (CSA) and bone strength index (= vBMD × CSA), of cortical bone in the femoral neck and was less correlated with aBMD or other bone structural parameters.

Racial Differences in Iliac Crest Cancellous Bone Composition: Implications for Preoperative Planning in Spinal Fusion Procedures.

This was a retrospective cohort study. The objective of this study was to determine whether race, specifically American white and American black, correlates with the ratio of cancellous to total bone at the iliac crest. Studies have demonstrated higher proximal femur bone density in American blacks than American whites. However, whether differences occur at the iliac crest, a common site for autologous graft material in spinal fusion surgery, is not well studied. Understanding such differences could aid orthopedic surgeon decision-making regarding graft options. A retrospective review was performed on 133 sequential patients ages 18-75 who underwent computed tomography scan of the pelvis, at a single academic medical center from January 1, 2014, to January 1, 2016. The cohort included 46 American white (21 females, 25 males) and 87 American black participants (40 females, 37 males), an average age of 51.8 years. Groups were matched regarding age, sex, body mass index, and Charlson Comorbidity Score. Measurements of cortical and cancellous bone thickness in the right and left iliac crests were performed using bone window protocol on computed tomography scans. Statistical significance was determined using a 2-tailed t test. The interobserver interclass correlation coefficient reliability (N=2) for measurements at the right iliac crest is 0.895 (95% confidence interval, 0.852-0.925), and the interclass correlation coefficient for the left iliac crest is 0.912 (95% confidence interval, 0.877-0.938). A statistically significant difference in the mean cancellous bone ratio was found between American black (0.667±0.065) and American white (0.750±0.051) groups (P<0.001). At the iliac crest, American black patients had a lower mean ratio of cancellous to the total bone as compared with American white patients. This population may benefit from alternative graft options. While iliac crest autograft remains the first option for fusion surgeries, alternative options should be considered to ensure that each patient receives the best-personalized care.

Interradicular distance and alveolar bone thickness for miniscrew insertion: a CBCT study of Persian adults with different sagittal skeletal patterns

BackgroundThis study aimed to assess the interradicular distance and alveolar bone thickness of Persian adults with different sagittal skeletal patterns for miniscrew insertion using cone-beam computed tomography (CBCT).MethodsThis cross-sectional study was conducted on maxillary and mandibular CBCT scans of 60 patients (18–35 years) in three groups (n = 20) of class I, II and III sagittal skeletal pattern. Anatomical and skeletal parameters were measured at 2, 4 and 6 mm apical to the cementoenamel junction (CEJ) by one examiner. The intra- and inter-class correlation coefficients were calculated to assess the intra, and interobserver reliability. Data were analyzed by ANOVA and Tukey’s test (alpha = 0.05).ResultsThe intra- and interobserver reliability were > 0.9 for all parameters. The largest inter-radicular distance in the maxilla was between the central incisors (1–1) in classes I and III, and between premolars (4–5) in class II patients. The largest inter-radicular distance in the mandible was between molar teeth (6–7) in all three classes. The buccal cortical plate thickness was maximum at the site of mandibular first and second molars (6–7). The posterior maxilla and mandible showed the maximum thickness of cancellous bone and alveolar process. Wide variations were noted in this respect between class I, II and III patients.ConclusionsThe area with maximum inter-radicular distance and optimal alveolar bone thickness for miniscrew insertion varies in different individuals, depending on their sagittal skeletal pattern.

Determination of the Volume and Density of Mandibular Ramus as a Donor Site Using CBCT.

This study aimed to assess the quantity and quality of available bone to provide the autologous bone graft from mandibular ramus. CBCT scans were collected and mandibular ramus was evaluated by measuring a variety of parameters including volume, bone height, cortical, and cancellous bone thickness. Data analysis was performed using descriptive statistics and inferential statistics. We used the Kolmogorov-Smirnov test for the evaluation of data normality. We then applied Pearson correlation and independent t-test for normal variables, and Spearman and Mann-Whitney correlation tests for abnormal variables. Statistical analysis was performed using SPSS version 19 and P value < 0.05 was considered significant. A total of 52 women and 32 men (aged 21 to 70) were included in this study. The mean bone volume was 2.7 ± 0.70 cm3 [95%confidence interval (CI) 1.3-4.5]. The mean bone density in the middle section was 1016.36 ± 231.58Gy value (95% CI 475.6-1520.9). Kolmogorov-Smirnov test revealed that the variables such as apical cortical/cancellous ratio (P = 0.005), middle-cancellous bone thickness (P = 0.016), and middle cortical/cancellous ratio (P = 0.005) were abnormal and the rest were normal. Bone density, as well as the amount of cortical bone in the middle and apical regions, had a significant reverse correlation with age (P < 0.001). The volume, density, and cortical/cancellous ratio are independent of sex. The reverse relationship between age and bone density, as well as the amount of cortical bone in several parts, indicates a decrease in bone quality with aging.

Morphometric and density comparisons of Bos taurus scapulae as a proxy to human frontal crania

BackgroundIn the absence of cadaveric tissues, forensic simulation, trauma modelling, and cranial surgical training necessitates a surrogate for the human calvaria. This study investigates the validity of Bos taurus scapulae as a proxy for human frontal bones by comparing the laminar and cancellous bone thickness, as well as the bone mineral density (BMD) of cadaveric frontal bones and adult Bos taurus scapulae.ResultsThis study aimed to validate the bovine scapulae as a valid proxy for forensic experiments, which benefit researchers and investigators who need to recreate forensic scenarios where synthetic proxies are found unsuitable due to their non-viscoelastic nature and cadaveric human models are unavailable due to ethical restrictions. Our results identified different total thicknesses of the relative bones, but non-different cortical measurements between human frontal bone and bovine scapulae. The bone mineral density is similar between both groups.ConclusionThis study has found Bos taurus scapulae to be a suitable proxy for human frontal bones as it has a similar morphology with regard to thickness and structure as well as a comparable density. However, there is a significant difference between the cancellous bone, and therefore, the overall thickness.

Radiological Assessment of Egyptian Mandible Morphometric Parameters Using Cone Beam Computed Tomography (CBCT)

Introduction Accurate appraisal of bone dimensions and morphology is essential for preoperative planning. The present study was conducted to estimate the different morphometric parameters and to determine the mandibular canal and mental foramen location using CBCT. Materials and Methods CBCT imaging of 48 Egyptians was performed. The mandibles were investigated around the 1st molar, for total height (TH), upper distance (UD) , lower distance (LD), total thickness (TT), buccal cortical bone thickness (BCB), lingual cortical bone thickness (LCB) and cancellous bone thickness (CAB), diameter of the mandibular canal (DOM) and gonial angle (GA). Variations in mandible shape and mental foremen sites were also assessed. Results A significant difference between the mean TH in both groups was detected, while the mean UD and LD showed insignificant differences. The mean values of TT and CAB were greater in males however the mean BCB and LCB were greater in females. DOM was greater in males but statistically insignificant. Statistically insignificant differences between the mean GA in females (greater) and males were observed. The TH, LD, TT and CAB, DOM showed positive correlations to the age in both groups however the UD, BCB, LCB and GA showed negative correlations. The commonest position of the mental foramen was opposite the apex of the fifth tooth (54.2%). The shape of the mandible were categorized into type A (83.3%), B (0%), C (10.4%) and straight (6.3%). Conclusion Mandibular measurements and morphology are unique and their assessment by CBCT becomes crucial before any dental implant.

Qualitative and morphological evaluation of the mandibular bone using computed tomography.

Determining the amount of cortical and cancellous bone present in the mandible is an important criterion for the selection of proper implant size and reduction of post implant placement complications. It becomes difficult to manage the presence of lingual undercuts when there is perforation of either the buccal or lingual cortical plates. Computed tomography (CT) images of the mandible can reduce the risk of complications by evaluating the thickness of cortical and cancellous bone in the mandible. Evaluate thickness of the buccal and lingual cortical plates and cancellous bone. Gender variation in the cancellous bone and cortical bone thickness. Determine the shape of the mandible. A retrospective study was conducted using the CT scan images of pathologies pertaining to the Head and Neck region. CT scan images of 30 patients, comprising of 22 males and 8 females. The mental foramen was considered as the anatomical landmark and the vertical marking was considered at a height of 20 mm from basal bone. The thickness of both cortical and cancellous bone was noted 6 mm anterior to it and 18 mm posterior. The shape of the buccal and lingual cortical bone was also considered. Statistical analysis was done using Student's t-test or Chi-square test. The mean thickness of cortical bone was more in anterior mandible than posterior mandible and cortical bone density was thickest at height of 20 mm, whereas for cancellous bone, it was highest at 5 mm from the basal bone, thickness. Buccal concavity, type A (68.2%), was the most common in the anterior region for males, followed by round shape, type C (56-58%) in the posterior region. For females, type C (25-31%) in the posterior region and lingual concavity, type B (18-30%) were the most common types in the anterior region. Lingual concavity may pose serious problems in cases of perforations during implant placement. Lingual cortical plates were thicker than the buccal cortical plates and it is concave anterior mandible. Thus, CT imaging can help in characterizing the quantity and morphology of the mandible.

Relationship between alveolar bone thickness, tooth root morphology, and sagittal skeletal pattern : A cone beam computed tomography study.

The goal of this work was to examine the relationship between sagittal facial pattern and thickness of alveolar bone in conjunction with root morphology of teeth by using cone beam computed tomography (CBCT). The study was carried out on the CBCT scans from 3group of patients (n = 20 in each group). The first group involved skeletal class1, the second group involved skeletal class2, and the third group involved skeletal class3 patients. In all, 14permanent teeth and interdental regions in the maxilla and mandible were evaluated. Root length and root width were measured on each tooth. Buccal cortical bone thickness, cancellous bone thickness, and lingual cortical bone thicknesses were measured in each interdental region. Analysis of variance, Kruskall-WallisH and Mann-WhitneyU tests were used for statistical comparisons. No significant difference was found between the groups for root length, root width, buccal cortical bone and lingual cortical bone thickness. A significant difference was observed between the groups for cancellous bone thickness as it was thicker in skeletal class2 group. Cortical bone was thicker in the mandible compared to maxilla on both buccal and lingual sides and it was thicker in the posterior region compared to the anterior region on the buccal side. Differences in cancellous bone thickness between different sagittal facial patterns and differences in cortical bone thickness between different alveolar regions should be taken into consideration when planning orthodontic tooth movements and anchorage mechanics.

Evaluation of the theoretical optimal angle of the tibial tunnel in transtibial anatomic posterior cruciate ligament reconstruction by computed tomography

Background“Killer turn” effect is a critical explanation for the recurrent posterior laxity following transtibial posterior cruciate ligament (PCL) reconstruction, which affected by the angle of the tibial tunnel. Meanwhile, excessive tunnel angle would have an adverse impact on the healing of tendon to bone. The purpose was to evaluate the theoretical optimal angle of the tibial tunnel in transtibial anatomic PCL reconstruction.MethodsThe measurements were performed on CT sagittal plane, including the thickness of cancellous bone (L1), the theoretical optimal angle of the tibial tunnel (TOA, which was measured between tibial plateau and the extension cord connecting the center of PCL insertion site with a point 5 mm superior from marrow cavity vertex), L2 - the distance from anterior tunnel aperture to anterior end of tibial plateau, L3 - the distance from anterior tunnel aperture to tibial tuberosity (lowest edge of patellar ligament attachment).ResultsThe value of TOA and L3 were 35.4 ± 7.9 ° and 26.8 ± 11.4 mm, respectively. L1 and L2 were higher in males than females (L1, P = 0.002; L2, P = 0.046). Regarding age, L1, TOA, L2 and L3 were higher in the 46–60 years group than 31–45 years group (P = 0.02, P = 0.001, P = 0.038, P = 0.032, respectively). With regard to height, L1 was lower in group I - < 1.66 m than group II - 1.66 to 1.75 m and group III - > 1.75 m (I v II, P = 0.015, I v III, P = 0.026). L2 was also lower in group I than group II and group III (I v II, P = 0.026, I v III, P = 0.006). TOA and L3 showed no significant differences among sex and height groups (P > 0.05).ConclusionsTOA (35.4 ° ± 7.9 °) and L3 (26.8 ± 11.4 mm) could be used as a reference for ideal tibial tunnel placement in transtibial anatomic PCL reconstruction, so as to prevent recurrent PCL laxity and ensure good graft healing. However, further clinical validation is needed.

The value of cross raft screws technique to prevent postoperative collapse of tibial plateau fracture

Objective To assess the clinical value of cross raft screws technique in preventing postoperative collapse of tibial plateau fracture. Methods From September 2014 to November 2017, data of 14 patients with tibial plateau fracture who were treated by cross raft screws technique were retrospectively analyzed. There were 9 males and 5 females aged from 30-65 years old (average, 44.4±1.7 years). There were 8 patients that the thickness of subchondral cancellous bone measured preoperatively by CT data was less than 4 mm, and 6 patients that the thickness of subchondral cancellous bone measured intraoperatively was less than 4 mm. 1/4 tubular plate was placed along the anterior rim of lateral tibial plateau, and the 3.5 mm cortical bone screws were fixed as bamboo raft from anterior to posterior through the plate. The collapse of tibial plateau after surgery were measured by CT scan after union of the fracture. The function of knee was evaluated by Rasmussen Anatomical and Functional Grading. Results The time of tubular plate procedure was 18 to 35 min (average, 24.1±5.4 min). All 14 patients were successfully followed-up for 13.8±5.1 months. The height of collapse preoperatively by CT scan was 5-21 mm (average, 8.00±1.40 mm). 3 days after the operation, the height between articular line and lateral articular surface was 0-2 mm (average, 0.80±0.06 mm). Compared with CT data preoperatively, the collapse was corrected postoperatively that was proved by CT scan (P< 0.05). After the fracture was healed, according to CT data, the height between articular line and lateral articular surface was 0-2 mm (average, 0.70±0.08 mm). Compared with CT data postoperatively, there was no postoperative collapse happened (P=0.466). The position and length of nails were placed appropriately. The average healing time of fracture was 3.6 months. There were no infection, nonunion and pain of tendon happened. The plate could be touched subcutaneously in 2 patients, who had no discomfort feelings. The patient's postoperative Rasmussen Anatomical Grading were 13-18 (average, 16.7), including 8 cases excellent and 6 cases good. The postoperative Rasmussen Functional Grading was 18-28 (average, 25.7), including 11 cases excellent and 3 cases good. Conclusion The cross raft screws technique is a good way to prevent the postoperative collapse of the lateral articular surface of tibial plateau. Key words: Tibial fractures; Fracture fixation, internal; Treatment outcome