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.

Relationship between cortical bone thickness and implant stability at the time of surgery and secondary stability after osseointegration measured using resonance frequency analysis

PURPOSE: It has been suggested that resonance frequency analysis (RFA) can measure changes in the stability of dental implants during osseointegration. This retrospective study aimed to evaluate dental implant stability at the time of surgery (primary stability; PS) and secondary stability (SS) after ossseointegration using RFA, and to investigate the relationship between implant stability and cortical bone thickness. METHODS: In total, 113 patients who attended the Tohoku University Hospital Dental Implant Center were included in this study. A total of 229 implants were placed in either the mandibular region (n = 118) or the maxilla region (n = 111), with bone augmentation procedures used in some cases. RFA was performed in 3 directions, and the lowest value was recorded. The preoperative thickness of cortical bone at the site of implant insertion was measured digitally using computed tomography, excluding cases of bone grafts and immediate implant placements. RESULTS: The mean implant stability quotient (ISQ) was 69.34±9.43 for PS and 75.99±6.23 for SS. The mandibular group had significantly higher mean ISQ values than the maxillary group for both PS and SS (P < 0.01). A significant difference was found in the mean ISQ values for PS between 1-stage and 2-stage surgery (P < 0.5). The mean ISQ values in the non-augmentation group were higher than in the augmentation group for both PS and SS (P < 0.01). A weak positive correlation was observed between cortical bone thickness and implant stability for both PS and SS in all cases (P < 0.01). CONCLUSIONS: Based on the present study, the ISQ may be affected by implant position site, the use of a bone graft, and cortical bone thickness before implant therapy.

Cortical bone thickness at common miniscrew implant placement sites with different vertical skeletal patterns in adults / 口腔疾病防治

Objective@#To provide some references of using miniscrew implants in clinical orthodontic treatment, the bone thickness of maxilla and mandible of different vertical facial type in adults with cone-beam CT (CBCT) was measured.@*Methods @#57 scanned patients were selected as subjects. Among them, 20 were included in the high-angle group, 22 in the normal-angle group, and 15 in the low-angle group. On volumetric images, we measured the buccal and palatal cortical bone thickness of maxilla, the buccal cortical bone thickness of mandible from canine to the second molar teeth at heights of 4.0 mm from cemento-enamel junction (CEJ). The mean of cortical bone thickness was compared between three groups.@*Results @#There were statistical differences among three different vertical facial groups in the cortical bone thickness (P<0.05). The high-angle group has the thinnest cortical bone while the low-angle group has the thickest.@*Conclusion @#Clinicians should be aware of the probability of thin cortical bone plates and the risk of miniscrew implant failures at maxillary posterior miniscrew implant sites in high-angle patients.

Spiral CT evaluation of the alveolar cortical bone mineral density and bone cortex thickness of teenagers and adults / 实用口腔医学杂志

Objective:To compare the alveolar cortical bone density and thickness of jaw bones between teenagers (12-18 years of age) and adults(19-48 years of age).Methods:Spiral computed tomographic images of 60 cases were obtained from the subjects with the ages of 12 to 48 years(27 Males and 33 females,35 teenagers and 25 adults).Buccal cortical bone thickness and density in Hounsfield units were measured at 12 interradicular sites and to a depth of 14 mm.Results:The alveolar cortical bone thicknesses and densities of the jaw bones significantly increased from the crest to base of alveolar crest.The average cortical bone thicknesses rangedfrom 1.0 to 1.5 mm in the anterior part of the jaw bones,1.1 to 1.8 mm in maxillary posterior area and 1.5 to 2.8 mm in the mandible posterior areas.The cortical bone thickness and density were greater in the mandible than in the maxilla(P ＜ 0.05).The thickness values did not show difference between males and females,between adolescents and adults.Higher values of bone density were found in the adults than in the teenagers(P ＜0.05).The highest bone density in the mandible posterior area of adults was observed,and the lowest bone density in the maxillary posterior area of adolescents.Conclusion:Alveolar cortical bone density of adolescents is lower than that of adults,especially in the maxilla posterior region.

Evaluation of buccal cortical bone thickness in maxillary posterior region for orthodontic micro-implants in children by using CBCT / 重庆医学

Objective To quantitatively evaluate the thickness of the buccal cortical bone in the posterior region of the maxillary for orthodontic micro‐implants in children .Methods Forty children (20 males and 20 females) in permanent dentition with Class Ⅱdivision 1 malocclusion were selected .The maxillary posterior alveolar bones of the subjects were scanned and reconstructed by cone‐beam computed tomography (CBCT) .The thickness of the cortical bone between the dental roots of the second upper premolar and the first upper molar at the height of 3 ,4 ,5 ,6 ,7 ,8 ,9 mm from the alveolar crest were determined .The data were analyzed sta‐tistically .Results The thickness of the cortical bone between the second upper premolar and the first upper molar was minimum at the height of 4 mm from the alveolar crest(P<0 .05) .The thickness of the cortical bone increased along with the distance increas‐ing from the alveolar crest at the height of 5 mm .The cortical bones in male were significantly thicker than those in female at the height of 7 ,8 ,9 mm (P<0 .05) .Conclusion The thickness of the buccal corticalbone in children in permanent dentition with ClassⅡ division 1 malocclusion changes with the measured vertical position .Micro‐implant anchorage is better to be placed in the area with a distance of 5 mm from the alveolar crest .

Three-dimensional evaluation of maxillary anterior alveolar bone for optimal placement of miniscrew implants / 대한치과교정학회지

OBJECTIVE: This study aimed to propose clinical guidelines for placing miniscrew implants using the results obtained from 3-dimensional analysis of maxillary anterior interdental alveolar bone by cone-beam computed tomography (CBCT). METHODS: By using CBCT data from 52 adult patients (17 men and 35 women; mean age, 27.9 years), alveolar bone were measured in 3 regions: between the maxillary central incisors (U1-U1), between the maxillary central incisor and maxillary lateral incisor (U1-U2), and between the maxillary lateral incisor and the canine (U2-U3). Cortical bone thickness, labio-palatal thickness, and interdental root distance were measured at 4 mm, 6 mm, and 8 mm apical to the interdental cementoenamel junction (ICEJ). RESULTS: The cortical bone thickness significantly increased from the U1-U1 region to the U2-U3 region (p < 0.05). The labio-palatal thickness was significantly less in the U1-U1 region (p < 0.05), and the interdental root distance was significantly less in the U1-U2 region (p < 0.05). CONCLUSIONS: The results of this study suggest that the interdental root regions U2-U3 and U1-U1 are the best sites for placing miniscrew implants into maxillary anterior alveolar bone.

Cortical and cancellous bone thickness on the anterior region of alveolar bone in Korean: a study of dentate human cadavers

PURPOSE: The cortical bone thickness on the anterior region is important for achieving implant stability. The purpose of this study was to examine the thickness of the cortical and cancellous bones on the anterior region of the maxilla and mandible. MATERIALS AND METHODS: Twenty-five cadaver heads were used (16 male and 9 female; mean death age, 56.7 years). After the long axis of alveolar process was set up, it was measured in 5 levels starting from 2 mm below the cementoenamel junction (L1) at intervals of 3 mm. All data was analysed statistically by one-way ANOVA at the .05 significance level. RESULTS: The cortical bone thickness according to measurement levels in both the labial and lingual sides increased from L1 to L5, and the lingual side below L3 was significantly thicker than the labial side on the maxilla and mandible. In particular, the labial cortical bone thickness in the maxilla was the thinnest compared to the other regions. The cancellous bone thickness according to measurement levels increased from L1 to L5 on the maxilla, and on the mandible it was the thinnest at the middle level of the root. CONCLUSION: For implant placement on the anterior region, a careful evaluation and full knowledge on the thickness of the cortical and cancellous bone are necessary, therefore, these results may provide an anatomic guideline to clinicians.

Evaluation of mandibular cortical bone thickness for placement of temporary anchorage devices (TADs) / 대한치과교정학회지

OBJECTIVE: In this study, we measured the cortical bone thickness in the mandibular buccal and lingual areas using computed tomography in order to evaluate the suitability of these areas for application of temporary anchorage devices (TADs) and to suggest a clinical guide for TADs. METHODS: The buccal and lingual cortical bone thickness was measured in 15 men and 15 women. Bone thickness was measured 4 mm apical to the interdental cementoenamel junction between the mandibular canine and the 2nd molar using the transaxial slices in computed tomography images. RESULTS: The cortical bone in the mandibular buccal and lingual areas was thicker in men than in women. In men, the mandibular lingual cortical bone was thicker than the buccal cortical bone, except between the 1st and 2nd molars on both sides. In women, the mandibular lingual cortical bone was thicker in all regions when compared to the buccal cortical bone. The mandibular buccal cortical bone thickness increased from the canine to the molars. The mandibular lingual cortical bone was thickest between the 1st and 2nd premolars, followed by the areas between the canine and 1st premolar, between the 2nd premolar and 1st molar, and between the 1st molar and 2nd molar. CONCLUSIONS: There is sufficient cortical bone for TAD applications in the mandibular buccal and lingual areas. This provides the basis and guidelines for the clinical use of TADs in the mandibular buccal and lingual areas.

Cortical Bone Thickness for Mini-implant Placement in Korean

Recently, mini-implant is popular in the orthodontic treatment due to its simplicity and convenient surgical procedure. The objective of this study is to provide the anatomical guideline for mini-implant placement by analysing the cortical bone thickness in Korean. Hemi-sections of sixteen maxillae and twenty-two mandibles with normal teeth were used. Interdental areas between the 1st premolar and the 2nd premolar (Group 1), the 2nd premolar and the 1st molar (Gruop 2), and the 1st molar and the 2nd molar (Group 3) were sectioned and then scanned. After setting the axis of teeth, the cortical bone thickness was measured at the distance of 2 mm, 4mm, 6 mm, and 8 mm from alveolar crest. The mean thickness of cortical bone in the maxilla according to distance from alveolar crest was 1.30 +/- 0.63 mm (2 mm), 1.49 +/- 0.62 mm (4mm), 1.72 +/- 0.64 mm (6mm), and 1.90 +/- 0.90 mm (8 mm) at the buccal side and 1.33 +/- 0.47 mm, 1.31 +/- 0.45 mm, 1.37 +/- 0.55 mm, and 1.39 +/- 0.58 mm at the palatal side. In the mandible, that was 3.14 +/- 1.71 mm, 4.31 +/- 2.22 mm, 4.23 +/- 1.94 mm, and 4.30 +/- 1.57 mm at the buccal side and 1.98 +/- 0.88 mm, 2.79 +/- 1.01 mm, 3.35 +/- 1.27 mm, and 3.93 +/- 1.38 mm at the lingual side. The buccal cortical bone thickness in the maxilla was decreased from Group 1 to Group 3, while the thickness of palatal side was no change. In the mandible, it did not show a tendency at the buccal side and it was decreased from Group 1 to Group 3 without significant difference at the lingual side. Therefore, the buccal side of the Group 1 and Group 2 in both the maxilla and mandible seems to be the most appropriate site for a mini-implant placement with taking the stability and retention.

Maxillary Soft Tissue and Cortical Bone Thickness for Mini-implant Placement / 체질인류학회지

The midpalatal suture area and maxillary interdental area are suitable site for the placement of orthodontic mini-implant. The purpose of this study was to provide a guideline to indicate the best location for mini-implant placement as it relates to the thickness of soft tissue and cortical bone. Fifteen maxilla from 15 cadavers were cut in midsagittal plane and buccopalatal plane to measure the thickness of soft tissue and cortical bone of midpalatal and maxillary posterior interdental areas. Sectioned samples were scanned and the thickness was measured. The thickness of soft tissue and cortical bone were measured at 6 points from the interdental papilla with 5-mm intervals in the mid-sagittal section. And, the thickness of soft tissue and cortical bone were also measured at 5 points from the alveolar crest with 1-mm intervals in the buccopalatal section. The mean and standard deviation of the measurement were calculated. Soft tissue thickness at the midpalatal suture area was 1.46 mm at 15 mm from the interdental papilla and remained uniformly thick posterior to this point, and steeply increased at 35 mm area posteriorly. Cortical bone thickness were greatest (2.13 mm) at 20 mm from the interdental papilla and remained uniformly thick posterior to this point, and decreased at 30 mm area posteriorly. Palatal soft tissues thickness in all groups was thinnest at the 1 mm from the alveolar crest and gradually increased from alveolar crest to apical portion. Cortical bone thickness in all groups was thickest at the 1 mm from the alveolar crest and slightly decreased from alveolar crest to apical portion. Buccal soft tissue thickness in all groups was thickest at the 1 mm from the alveolar crest and gradually decreased from alveolar crest to apical portion. Cortical bone thickness in all groups was thinnest at the 1 mm from the alveolar crest and slightly increased from alveolar crest to apical portion. Soft tissue thicknesses were greater on the palatal side than on the buccal side. Cortical bone thicknesses of the buccal side were thicker than the palatal side. These results provide anatomical data of soft tissue and cortical bone thickness to assist in the determination of safe location for the mini-implant placement in the midpalatal and maxillary interdental areas.

Cortical bone thickness and root proximity at mandibular interradicular sites: implications for orthodontic mini-implant placement / 대한치과교정학회지

OBJECTIVE: The purpose of this study was to provide clinical guidelines to indicate the best location for mini-implants as it relates to the cortical bone thickness and root proximity. METHODS: CT images from 14 men and 14 women were used to evaluate the buccal interradicular cortical bone thickness and root proximity from mesial to the central incisor to the 2nd molar. Cortical bone thickness was measured at 4 different angles including 0degrees, 15degrees, 30degrees, and 45degrees. RESULTS: There was a statistically significant difference in cortical bone thickness between the second premolar/ first permanent molar site, central incisor/central incisor site, between the first/second permanent molar site and in the anterior region. A statistically significant difference in cortical bone thickness was also found when the angulation of placement was increased except for the 2 mm level from the alveolar crest. Interradicular spaces at the 1st/2nd premolar, 2nd premolar/1st permanent molar and 1st/2nd permanent molar sites are considered to be wide enough for mini-implant placement without root damage. CONCLUSIONS: Given the limits of this study, mini-implants for orthodontic anchorage may be well placed at the 4 and 6 mm level from the alveolar crest in the posterior region with a 30degrees and 45degrees angulation upon placement.

Three dimensional finite element method for stress distribution on the length and diameter of orthodontic miniscrew and cortical bone thickness / 대한치과교정학회지

The purpose of the present study is to evaluate the stress distribution on the length and diameter of the miniscrew and cortical bone width. Three dimensional finite element models were made of diameter 1.2mm, 1.6mm, 2.0mm and length 6.0mm, 8.0mm, 10.0mm, 12.0mm and cortical bone width 1.0mm. Also, another three dimensional finite element models were made of diameter 1.2mm, 1.6mm, 2.0mm and length 8.0mm and cortical bone width 1.0mm, 1.5mm, 2.0mm, 2.5mm. Two-hundred grams horizontal force were applied on the center of the miniscrew head and at that stress distribution and its magnitude had been analyzed by ANSYS, which is three dimensional finite element analysis program. The obtained results were as follows : 1. The comparison of the maximum von-Mises stress in the miniscrew showed that as the diameter increases from 1.2mm to 2.0mm stress has been decreased, while on the same diameter stress was not changed regardless of the length change. 2. The comparison of the maximum von-Mises stress in the cortical and cancellous bone showed that as the diameter increases from 1.2mm to 2.0mm stress has been decreased, while on the same diameter stress was not changed regardless of the length change. 3. In the analysis of the stress distribution in the cortical and cancellous bone, the most of the stress had been absorbed in the cortical bone, and did not transmitted much to the cancellous bone. 4. In the analysis of the maximum von-Mises stress according to the cortical bone width, the same diameter of the miniscrew showed a constant stress value regardless of the cortical bone width change. The above results suggest that the maintenance of the miniscrew is more reliable on diameter than length of the miniscrew.

Study Of Maxillary Cortical Bone Thickness For Skeletal Anchorage System In Korean

Recently, Skeletal Anchorage System (SAS) has been focused clinically with the view point that it could provide the absolute intraoral anchorage. First, it began to be used for the patient of orthognathic surgery who had difficulty in taking intermaxillary fixation due to multiple loss of teeth. And then, its uses have been extended to many cases, the control of bone segments after orthognathic surgery, stable anchorage in orthodontic treatment, and anchorage for temporary prosthesis and so on. SAS has been developed as dental implants technique has been developed and also called in several names; mini-screw anchorage, micro-screw anchorage, mini-implant anchorage, micro-implant anchorage (MIA), and orthosystem implant etc. Now many clinicians use SAS, but the anatomical knowledges for the installed depth of intraosseous screws are totally dependent on general experiences. So we try to study for the cortical thickness of maxilla and mandible in Korean adults without any pathologic conditions with the use of Computed Tomography at the representative sites for the screw installation.

A Numerical Study For The Variation Of Cortical Bone Thickness With 6 Endosseous Implant Shapes

Dental implant is increasingly used to rehabilitate the masticatory function of missing teeth. Several types of dental implant have been designed to give an optimal stress distribution to the surrounding bone, In this study, six typer of implant were investigated using finite element methods 1)how the variation of cortical bone thickness affects the stress distribution in bony regions depending upon implant types, and 2) which type gives the best characteristics in the sense of stress distribution and stability. The hybrid-type implant with tapered cylinder and screw gave the optimum properties in view of stability and response due to variation of cortical bone thickness.