Regression Equation For Age Estimation Research Articles

PREDICTIVE ABILITY OF MANDIBULAR THIRD MOLAR IN ESTIMATION OF CHRONOLOGICAL AGE

Objective: To determine the predictive ability of mandibular third molar in estimation of chronological age
 Material and methods: This is cross sectional descriptive study was conducted at Saidu college of Dentistry, Swat on 120 participants. The inclusion criteria were both males and females, age from 13 to 25 years, having good quality panoramic X-ray clearly showing lower third molar area. Participants with dental anomalies like oligodontia, Dentinogenesis/Amelogenesis imperfecta, fracture affecting angular region of mandible were excluded. Age, sex and tooth mineralization of lower third molar were recorded. Linear regression was applied using age as dependent and maturation stages of third molar as independent variable.
 Results: The mean age was 16.85±2.39 years. The females were 78 (65%) and males were 42 (35%). Overall the model shows that in 79.9% participant the variation in age can be explained by maturation stages of third molar and gender. The regression equation for age estimation is age= 11.42+1.68x(maturation stage) + 0.13x(gender).
 Conclusion: Mandibular third tooth maturation stages are useful in prediction of chronological age of the patients.

Age Estimation in Han Adults by Thin-Layer CT Scan of Cranial Sutures.

Objective To explore the value of degree of cranial suture closure in forensic adult age estimation by thin-layer CT scan and establish an adult age estimation model of the Han nationality. Methods Thin-layer CT scan samples of the heads of 220 healthy Sichuan Han adults （110 males, 110 females） aged 20 to 70 were collected, of which 20 samples （10 males, 10 females） were randomly selected as test samples. The sagittal suture, coronal suture （both left and right） and lambdoid suture （both left and right） were respectively and equally divided into 2 segments, and every segment was equally divided into 10 layers and the corresponding multiplanar reformation （MPR） images were selected. The closure of cranial sutures on MPR images was classified into the grades 1-7. The correlations between cranial sutures and age were analyzed to build regression equation for age estimation. Results The degree of closure of sagittal suture, coronal suture （both left and right） and lambdoid suture （both left and right） was positively correlated with age. The coefficient of determination （R2） of regression equation was 0.419 in males, 0.589 in females, and 0.522 in all samples. The results of the verification test showed that the mean absolute error （MAE） was 6.39 years in males, 6.16 years in females, and 6.29 years in all samples. Conclusion There was a higher accuracy in adult age estimation by thin-layer CT scan of cranial sutures. The age of Han nationality adults can be estimated by the degree of cranial sutures closure.

A novel method of age estimation in children using three-dimensional surface area analyses of maxillary canine apices.

The study aimed to develop a novel and reliable age estimation method using three-dimensional surface area analyses of maxillary canine apices among Malaysian children using CBCT data. A validated regression equation for age estimation was derived and correlation between chronological age and the surface areas of the developing maxillary canine's apices were investigated. Variations based on ethnicities, gender and status of root development were also investigated in terms of fit to the age estimation model. CBCT images of the patients ranging in age from 7 to 14years were included in the study. Training sample of 191 intact permanent maxillary canines was selected from 191 CBCT images belonging to 100 Malays and 91 Chinese. Moreover, an independent validation sample of 96 permanent maxillary canines was selected from 96 CBCT images belonging to 48 Malays and 48 Chinese. Three-dimensional image modeling and surface area analyses of the developing canine's apices were performed using Mimics and 3-Matics software. A strong correlation (r=0.978) was observed between chronological age and surface area of the developing maxillary canine's apices. 95.6% of the variation in age can be explained by surface area of canine's apices, gender and status of the root development (open/closed apices). However, ethnicity did not contributed to the fit of age estimation model. Female showed advanced development as compared to male. Mean absolute error values indicated that this newly developed 3D surface area analyses of canine apex can be used as a reliable method for age estimation among Malaysian children.

Age estimation in Western Chinese adults by pulp–tooth volume ratios using cone-beam computed tomography

ABSTRACT The aim of this study was to develop population-specific regression equations for age estimation by investigating the correlation between chronological age and pulp–tooth volume ratios in three types of anterior teeth using cone-beam computed tomography (CBCT) in the Western Chinese population. Three hundred and ninety-two CBCT images of 207 female and 185 male individuals, aged between 16 to 76 years were evaluated. Mimics software was used to calculate the pulp–tooth volume ratios (PTVR) from CBCT images. Regression analysis was conducted with chronological age as a dependent variable and PTVR as an independent variable to establish a mathematical model for age estimation. The mean absolute error (MAE) was calculated to evaluate the accuracy of the regression model using an independent validation sample. Among the three types of anterior teeth, the left maxillary lateral incisor provides the most accurate age prediction for males (MAE = 6.804), and the left maxillary central incisor gave the most accurate results for females (MAE = 6.104). The statistical analysis also found gender differences exist in the PTVR for three types of anterior teeth. This study revealed that gender and tooth type specific equations are recommended when using the PTVR for age estimation.

Correlation between cone-beam CT images of the third and fourth cervical vertebrae and age in female skeletal class Ⅰ patients aged between 9 and 17 years in Qingdao

Objective: To analyze the correlation between the age and the cone-beam CT (CBCT) images of the third and fourth cervical vertebrae in female skeletal class Ⅰ patients aged between 9 and 17 years, and to establish a quantitative evaluation method for calculating the age. Methods: CBCT images of 108 female skeletal class Ⅰ patients aged between 9 and 17 years were collected from Qingdao Stomatological Hospital from September, 2017 to March, 2019. The two-dimensional linear values (AH: height of anterior edge of vertebral body; H: height of middle part of vertebral body; PH: height of posterior edge of vertebral body; AP: width of vertebral body), the two-dimensional linear ratio values (AH/PH, AH/AP, AH/H, H/AP, H/PH, PH/AP) and the three-dimensional volume values of the third vertical vertebrae (C3) and the fourth vertical vertebrae (C4) were measured. By Exponential transformation of measurements and multiple linear regression analysis, the optimal index for evaluating age were screened, and the fitting degree of multiple linear regression equation (R(2)) and the accuracy of age estimation (SEE) were compared. CBCT images of 27 female skeletal class Ⅰ patients aged from 9 to 17 years were added from Qingdao Stomatological Hospital between April, 2019 and July, 2019, by which the accuracy of the regression equation was verified. Results: Multiple linear regression equation for age estimation based on two-dimensional linear indexes was as follows: Y=-113.928+33.743×e(AH)(3)(/100)+58.844×e(PH)(4)(/100)+20.590×e(AP)(4)(/100)( "e" was a natural constant, e≈2.718), R(2)=0.745, SEE=1.31. Multiple linear regression equation for age estimation based on two-dimensional linear ratio indexes was as follows: Y=-0.076-2.284×e(A)H(3)/PH(3)+3.227×e(A)H(3)/AP(3)+2.149×e(A)H(3)/H(3)+1.961×e(A)H(4)/H(4), R(2)=0.576, SEE=1.70. Multiple linear regression equation of age estimation by the volume index was as follows: Y=-16.828+22.184×e(V)(3)(/10 000), R(2)=0.555, SEE=1.71. The data of 27 new patients were tested. The CBCT measurement index of C3 and C4 vertebral bodies inferred the fitting degree (R(2)) and accuracy (SEE) of the equation of the age estimation. The two-dimensional linear value was superior to the two-dimensional linear ratio and the latter was superior to the three-dimensional volume value. The standard error of the estimate about them was 1.74, 2.00 and 2.37, respectively. Conclusions: The two-dimensional linear index of CBCT images of C3 and C4 could be used to estimate the age of 9 to 17-year-old female skeletal class Ⅰ patients, and the accuracy of the method was higher than that of two-dimensional ratio index and three-dimensional volume index.

Juvenile versus adult: A new approach for age estimation from 3-dimensional analyses of the mandibular third molar apices

Abstract Rapidly evolving three-dimensional imaging techniques can be effectively employed in forensic sciences to overcome the limitations of two-dimensional imaging modalities. The aim of the present study was to find a threshold value of 18 years age among Malays to differentiate juvenile verses adults based on three-dimensional image analysis of developing mandibular third molars apices. The study also investigated the correlation between chronological age and the surface area of developing mandibular third molars apices. Malay specific regression equation for age estimation was derived. Seventy three mandibular molars were selected from 73 CBCT images belonging to 37 male and 36 female, ranging in age from 15 to 23 years. Mimics and 3-Matics software were employed to generate 3D image models and quantification of surface area analysis of developing mandibular third molars. The results indicated a strong inverse correlation (r = 0.918, SE = 1.025) between chronological age and the predictor variables. The R-Square (R2) value showed that 84.2% of the variation in age can be explained by surface area of the apices, and status of the root development (open/closed apices). Post hoc analysis indicated that the mean value of apex surface area of 18 years age group was significantly different from the mean values of 15, 16, 17, 22 and 23 years age groups. The results indicated that (based on the 95% confidence interval) if the apex surface area is below 9.25 mm2, then it is more likely that the Malay person is 18 years of age or above, irrespective of gender.

Discrepancy between Self-reported and Recorded Age and Height among Students: a Forensic Anthropological Investigation

Age and stature estimation have apparent implications in personal identification in the events of murder, accidents or natural disaster mainly concern with forensic identification analysis. Self-reported anthropometric data is convenient and inexpensive, but relying on this data requires an accurate estimation of age and height. The biasness, precision, and accuracy of adult’s self-reported age and height across subpopulations were examined using a representative sample of adults. Aim of the present study is to report bias in an individual’s reported and documented age and height estimates. The study sample were included more than 200 young adult students (100 male and 100 female subjects approximately) from Panjab university, Chandigarh, age from 18 to 25. Linear and multiple regression analysis were done to formulate equations which would be helpful for estimation of stature and age from self-reported data for both male and females. The best correlation estimation in multiple and linear regression equations for age estimation in male was shown self-reported data whereas in females reported to be data from parents rather than self-reported data , females tends to decrease their age number as shown in results while in stature best variable is self-reported. The weakest correlation was reported to be data from close friends in both males and females.

Maximum length of deciduous dentition as an indicator of age during the first year of life: Methodological validation in a contemporary osteological collection

Out of all the available methods for estimating age at death from immature human skeletal remains, those based on odontometric variables of deciduous dentition have proved to be one of the most accurate. The development of odontometric methods has been improved through the creation of documented human osteological collections, allowing their validation in different populations. The present study aims to test the regression equations for age estimation proposed by Liversidge et al. 1993, Irurita Olivares et al. 2014, and Cardoso et al. 2019, on the basis of the maximum length of deciduous teeth in an Argentinian sample of 35 infants of known age at death. The results showed that the absolute mean difference between estimated and chronological age was 5.76±6.33 weeks for Liversidge’s method, 5.71±6.41 weeks for Irurita Olivares’s method, and 6.79±5.80 for Cardoso’s method. It was also found that, for Liversidge’s method, the canines provided the most accurate and the least biased estimations. For Irurita Olivares’s method, mandibular anterior teeth were the most accurate, while the first mandibular molars offered the least biased estimations. For Cardoso’s method, the canines presented the most accurate estimations, while the lateral incisors the least biased ones. Finally, 95% confidence intervals of estimated ages were calculated for each method, finding that Irurita Olivares’s method provided the most reliable age estimations when using mandibular central incisors and mandibular first molars.

Three-dimensional image analysis of developing mandibular third molars apices for age estimation: A study using CBCT data enhanced with Mimics & 3-Matics software.

Three-dimensional imaging has improved the method of analysis in many forensic science investigations. The study aimed to derive regression equation for age estimation by investigating the relationship between chronological age and surface area of the developing mandibular 3rd molars apices. Furthermore, other predictor variables: ethnicity (Malay and Chinese), gender and status of the root development completion (open/closed apices) were also investigated in terms of fit to the age estimation model. One hundred and twenty eight training and 55 validation samples of intact mandibular 3rd molars were selected from 183 CBCT scans. The samples comprised of 93 Malays and 90 Chinese, ranging in age from 13 to 24 years. Three-dimensional image modeling and surface area analysis of the developing mandibular 3rd molars apices were performed using Mimics and 3-Matics software. Multiple linear regression analysis was used to derive age estimation model using chronological age as a dependent variable and surface area of the apices, ethnicity, gender and status of the root development completion (open/closed apices) as predictor variables. A strong inverse correlation (r = 0.95, SD = 1.144) was observed between chronological age and all the predictor variables. The results showed that 89.6% of the variation in age can be explained by the predictor variables. Mean absolute error (MAE) value of 0.8223 was observed when the derived regression equation was tested on the independent validation sample. In conclusion, three-dimensional surface area analysis of the developing mandibular 3rd molars apices can be used as a reliable method for age estimation.

Age regression for Malaysian males using cortical bone Histomorphometry

Bone microstructures have the capability to record the variations in its structure that occur during the life span. These variations can be analysed to estimate human age at death. This study analysed 30 Malaysian male samples in order to create a regression equation for age estimation. Bone samples were collected from human long bones i.e humerus, radius, ulna, tibia, fibula and femur. Two morphological and five histological variables were selected for analysis. Cortical thickness and medullar cavity diameter did not show any significant relation with increasing age however haversian canal parameters and osteon count showed significant correlation with age. Regression equation with lowest SEE 7.2 was based on Haversian canal area, haversian canal radius and osteon count. The regression equation estimated age at death within 10 years of range for 85% samples. The mean value of the known ages was 39.8 years while the mean value of the estimated ages was 37.03 years. Increasing number of samples including female samples for further research might produce promising results.

Mental foramen: A predictor of age and gender and guide for various procedures

Background: The distance from the inferior border of mental foramen (MF) to lower border of mandible remains constant throughout the life. Considering this fact the present study was carried out to determine role of MF in age and gender estimation and also its importance in planning various treatments. Aims and Objective: (1) To determine the most common type and shape of MF 2) To measure the height of the mandibular body (H), the distance between the superior margin of the MF to the alveolar crest (SM-AC), the distance between the superior margin of the MF to the inferior border of the mandible (SM-IB), the distance between the inferior margin of the MF to the inferior border (IM-IB) on the right side and left side. (3) To compare the above measurements for age and gender determination. (4) To determine effect of various factors on above measurements (5) to evaluate whether any significant difference in measurement occurs on right and left side. (6) To derive a regression equation for age estimation. Materials and Methods: A total of 300 Orthopantomogram were studied. Measurements such as H, SM-AC, SM-IB and IM-IB were carried out on both sides on type II MF in males and females in all the six age groups. Statistical analysis was carried using IBM SPSS version 24 to determine differences in measurements and linear regression analysis was carried out to determine age of individuals. Result: The most common appearance of MF was type II and shape was oval. Statistically significant differences occurred in measurements using which regressive equation for age estimation was derived for males & females. Conclusion: MF, being a stable landmark in mandible, serves as a good indicator for the determination of age and gender. Hence, using certain measurements related to MF, it can help in determining the age of the individual. Further, its position and distance from the alveolar crest serve as a guide for orthognathic surgeries, implant placement, and pre-prosthetic surgery.

Mandibular Ramus and Gonial Angle Measurements as Predictors of Sex and Age in an Egyptian Population Sample: A Digital Panoramic Study

Objective: The determination of sex and age is necessary in forensic practice and medico legal purposes. Mandible may play a vital role in sex estimation as it is the most dimorphic bone of skull that often recovered intact. In this respect, the availability of plentiful antemortem orthopantomograms may be of great value in studying and developing population specific standards for accurate sex and age estimation. Therefore, the purpose of the current study was to assess the usefulness of various mandibular ramus linear and gonial angle measurements on digital panoramic images as indicators for sex and age in an Egyptian population sample. Methods: 191 panoramic images (105 males and 86 females) of Egyptian patients aged (6-70) years old were selected. Five mandibular ramus linear measurements (upper ramus breadth, lower ramus breadth, projective height,condylar ramus height and coronoid ramus height) and gonial angle measurements were performed bilaterally resulting in a total of 382 rami being assessed. Stepwise discriminant and regression analyses were performed to determine the most significant predictors of sex and age respectively. Results: Males showed statistically significant higher mean linear ramus measurements and lower mean gonial angle values than females. Condylar and coronoid ramus heights were the most significant predictors for sex and age respectively. The discriminate function equation was: (D= 14.698 - 1.895 Condylar ramus height) with an accuracy of 81% in males and 77.9% in females and an overall accuracy of 79.6%. The regression equation for age estimation in the whole studied sample was: (Age= - 32.306 + 8.481 Coronoid ramus height) that yields no significance on comparing actual and estimated ages. Conclusion: In the selected Egyptian population sample, the mandibular ramus showed a high sexual dimorphism and proved to be beneficial in sex and age estimation; while, the gonial angle could assist in sex estimation only.

The study on telomere length for age estimation in a Thai population.

Age is one of the key parameters in establishing a physical characteristic profile of an individual. For biological evidence left in crime scenes such as blood, saliva, hair, etc, the evidence owner's age can be determined only by DNA extracted from these materials. Previous researches have found that there are certain DNA regions with specialized characteristic and function called telomere being able to predict age. The present study was to determine the correlation between telomere length and age as well as the effect of sex on the correlation and to create linear regression equation for age estimation in Thai population for forensic purposes. Blood samples obtained from unrelated healthy Thai fresh cadavers without anatomical organ abnormalities were used in this study. All cadaver subjects underwent the postmortem examination in jurisdiction of the Department of Forensic Medicine, Faculty of Medicine Siriraj Hospital, Mahidol University, and Institute of Forensic Medicine, Police General Hospital. Fifty blood samples from both sexes of all ages divided into 6 groups for equal age distribution (0-11, 12-23, 24-35, 36-47, 48-59, and 60 years old and older) were collected for a total of 100 samples. The extracted genomic DNA samples were then subjected to telomere length estimation by terminal restriction fragment (TRF) assay. The results showed that the mean TRF length was inversely correlated with age (r = -0.625), and sex did not have a statistically significant influence on the association between age and mean TRF length (P > 0.05). The obtained linear regression equation was y = 113.538 ± 9.604 - 0.012 × (R = 0.391; P < 0.001). However, the correlation was too low to be used for age estimation with high certainty and a possible reason for this in part would be the postmortem DNA degradation at some level, even using fresh cadaver blood, and other biological factors such as ethnicity and DNA sources. Roughly, those individuals who had a mean TRF length longer than 6.3 kilobase (kb), between 5.5 and 6.3 kb, and shorter than 5.5 kb aged younger than 28 years, 30 to 44 years, and older than 46 years, respectively (P < 0.01). As a preliminary study, this study highlighted that telomere length could act as a useful biomarker of aging in human population and might be used for rough age estimation in a Thai population. However, further studies with a larger sample size and/or in living human bloods as well as other cell types are recommended to support the results of this study.

Age estimation based on three-dimensional measurement of mandibular central incisors in Japanese

The purpose of this study was to investigate an age estimation method that considers gender as well as three-dimensional measurement of the components, specifically enamel and dentin. A total of 155 mandibular central incisors aged 12–79 years old which was chosen from the collection stored at the Department of Anatomy in Tokyo Dental College and had no opened apex, caries or restorative treatment, were examined. Samples were scanned using micro-CT HMX225 ACTIS4. Based on the sliced image data, three-dimensional structures were obtained and the volumes of enamel, dentin, and pulp cavity were measured. Regression equations for age estimation were then determined. The accuracy of age estimation equations for each region, volume ratio, and sex was assessed using the determination coefficient R 2 as well as the standard errors of estimated values. The root region alone had a comparable accuracy to that of the whole tooth and the crown region had a relatively lower accuracy. In the whole tooth and the crown region, slightly higher correlations were observed for pulp/tooth volume ratios in which enamel was excluded. Females tended to have higher accuracy compared to males. The estimated age was higher in males compared to females for the same volume ratio of the pulp cavity. The highest correlation in both genders with age was observed for the volume ratio of the pulp cavity to the whole tooth excluding the enamel (males, R 2 = 0.67; females, R 2 = 0.76). The 95% confidence intervals for the population regression showed different distributions for each sex. In the 95% prediction intervals for age estimation, females tended to have narrower intervals and higher accuracy compared to males. Therefore, the use of gender-specific equations is recommended for age estimation.

Age estimation on the female sternum by quantification theory I and stepwise regression analysis

One hundred and nine sternums from Chinese females aged 18–50 years were examined in this study. Six morphological characteristics and their changing degree in the female sternum were observed and scored. The data were statistically processed by quantification theory I and stepwise regression analysis on a computer and the following regression equation for age estimation of the female sternum was calculated: y = 19.28 + 1.83 x 1 + 1.66 x 2 + 3.02 x 3 + 1.57 x 4 + 3.02 x 5 + 7.75 x 6 + 1.25 x 7 + 3.45 x 8 + 4.88 x 9 + 0.82 x 10 + 2.76 x 11 + 2.48 x 12 + 7.84 x 13 + 1.26 x 14 + 3.80 x 15 (the correlation coefficient R = 0.9774, the standard deviation S = 2.20, F > 0.01). For convenience, the changing degree of the morphological characters and the equation were also converted into two tables. This method of age estimation on the female sternum is simple and accurate and is of importance to forensic medicine and anthropology.

Histological estimation of age at death using microradiographs of humeral compact bone

The purpose of this study is to develop an age estimating method for skeletal remains using microradiographs of compact bone. Compact bones of the humerus were collected from 40 Japanese males ranging from 23 to 80 years of age. Microradiographs taken from cross-sections were histomorphometrically examined by using an image analyzer. Histological parameters used in this study included 10 items, that is, osteon number, double-zoned osteon number, type II osteon number, low-density osteon number, osteon fragment number, resorption space number, total and average osteon area, and total and average Haversian canal area. The osteon fragment number showed the highest correlation coefficient with advancing age ( r = 0.786). The measurement data obtained from 10 histological parameters were subjected to multiple regression analysis for producing multiple regression equations for age estimation. In practice, 8 histological parameters were selected for the equation and its multiple correlation coefficient and standard error of estimate were 0.903 and 6.1, respectively.

Estimation of age at death from second metacarpals

This study examined the estimation of age at death from the second metacarpal in 227 individuals aged 30-98 years. Variables ascertained from each bone were: cortical thickness and microdensitometric cortical bone density measured on radiographs of the bone and total osteon count and density recorded on microradiographs of the complete cross section at its midshaft. Based on the latter two variables, two age groups were formed; a middle age group representing those individuals aged 30-65 years, and an older group aged 65+. Stepwise regression analysis of the four variables produced a series of regression equations for age estimation for the middle, old and combined age groups for each sex and sexes combined. Sex-specific equations provided better results than nonspecific ones, especially in females. Total osteon density and combined cortical thickness were found to be the most useful estimators in the middle and the old age group, respectively. The standard error of estimate was 6.71 and 6.90 years in each age group for the sexes combined. In the combined age group, age could be estimated accurately from total osteon count, cortical thickness and MD cortical bone density with the standard error of estimate of 11.10 years. The relative error of estimate ranged within +/- 30% in almost all individuals aged above 60 years.

Histologic estimation of age at death using the anterior cortex of the femur

This report describes a new histologic method for determination of age at death, the latest in a series of studies that began with Kerley's pioneer presentation in 1965. The study population was collected from 328 documented individuals from an anatomy dissecting room in the United States, from two modern cemeteries in the Dominican Republic, and from autopsies performed in a Chilean hospital. Undecalcified thin sections 1.0 cm wide were made from specimens taken from the femoral midshaft directly opposite the linea aspera. Five 0.886 mm2 fields were located at the periosteal edge and photographed, mainly for purposes of defining the fields and providing a permanent record. Secondary osteons, type II osteons, osteon fragments, resorption spaces, and non-Haversian canals were recorded as number/mm2, and a 100-space grid was used to measure average percent of unremodeled, osteonal, and fragmental bone. Stepwise regression analysis of the measurements produced a series of regression equations for age estimation for females, males, and sexes combined. Most equations have a standard error of estimate of about 10 years, but the coefficients of determination (r2) range from 0.48 to 0.72. In practice, sex-specific equations gave better results than opposite-sex or nonspecific equations, mainly because males and females differed in the pattern of relations between osteons and osteon fragments with advancing age.

Estimation of age at death by tibial osteon remodeling in an autopsy series

Estimation of age at death by histological methods in tibiae has been found to be inaccurate in individuals less than 55 years of age. This study describes reasons for the inaccurate age estimates and provides a new regression equation for age estimation. Bone cores were removed from tibiae in 53 individuals at autopsy ranging in age from 17 years to 53 years of age; 48 males and 5 females. The sample contained 41 whites and 12 blacks. Variables ascertained from each core were: cortical thickness, cortical bone density, secondary osteon number, area, and perimeter, and Haversian canal area and perimeter. The results showed significant differences in secondary osteon number, area, and perimeter between groups aged less than and greater than 35 years of age. Multiple linear regression analysis indicated osteon number to be the best predictor of age in this sample aged less than 55 years of age. Age at death was accurately estimated for 11 additional forensic cases using osteon number in tibiae. No significant histological differences were observed between males and females and between blacks and caucasians.