Variations in the Trabecular Bone Ratio of the Maxilla According to Sex, Age, and Region Using Micro-Computed Tomography in Koreans

Age estimation using postmortem computed tomography-based Hounsfield unit values of the palate and mandibular condyle and the Eichner classification

Age estimation is important in forensic investigations of unidentified human remains. This study assessed the correlation between age and Hounsfield unit (HU) values of the palate and mandibular condyle based on postmortem computed tomography (CT) and analyzed the influence of occlusal support in developing an age estimation method for Japanese individuals, including older adults. The sample consisted of a training dataset (357 cadavers) and a validation dataset (300 cadavers) that underwent postmortem CT. Three measurements were selected: the respective HU values of the palate and mandibular condyle and the Eichner classification. The correlation coefficients between age and HU values were also evaluated. Multiple stepwise regression analysis was performed to evaluate the significance of four parameters (sex, respective HU values of the palate and mandibular condyle, and the Eichner classification) for age estimation and to determine the best age estimation formula. In the validation tests, inaccuracy and bias were calculated for the groups aged ≥65 or <65 years. Significant correlations between age and HU values of the palate and mandibular condyle were observed, regardless of sex. In multiple stepwise regression analysis, all variables except sex were significantly correlated with age. The age estimation formula from the regression analysis was useful, and the validation test exhibited high accuracy, especially in older adults. The HU values of the palate and mandibular condyle and the Eichner classification are useful for age estimation in Japanese individuals.

Evaluation of the compatibility of C2, C3, and C4 fractal dimension values with hand-wrist and cervical vertebra maturation methods in determining skeletal maturation

OBJECTIVES

To examine the correlation between the fractal dimension (FD) values of cervical vertebrae (C2, C3, and C4) and hand-wrist maturation (HWM) and cervical vertebra maturation (CVM) methods. In addition, the correlation between the pubertal growth spurt (PGS) and FD values was examined.

METHODS

The lateral cephalometric and hand-wrist radiographs of 120 subjects (61 females and 59 males) aged 8-18 years with a mean age of 13 years, were evaluated retrospectively. The CVM stages were determined in accordance with Hassel-Farman's modification of Lamparski criteria. The HWM stages were determined in accordance with Björk and Grave-Brown criteria. Both HWM and CVM stages were divided into two according to PGS. Fractal analysis of cervical vertebrae was performed according to the White-Rudolph method. The relationships between HWM stages, CVM stages and other variables were evaluated by Spearman's rank-order correlation coefficient. The relationships between FD values, chronological age, and divided stages were evaluated by the Pearson correlation coefficient. The Mann-Whitney U test was used to compare the FD values of two divided stages.

RESULTS

There were positive and statistically significant positive correlations between chronological age and both HWM and CVM stages. There was a positive and statistically significant correlation between CVM and HWM stages. In females and total, there were negative and statistically significant correlations between C4 FD values and divided HWM stages, and the differences between C4 FD values of divided HWM stages were also statistically significant. In total, there was a negative and statistically significant correlation between C4 FD values and divided CVM stages, and the difference between C4 FD values of divided CVM stages was also statistically significant.

CONCLUSION

The negative correlations found between C4 FD values and divided HWM and CVM stages suggest the fractal analysis of cervical vertebrae, especially of C4, may be used as an objective tool for evaluating the PGS.

3-D Evaluation of temporary skeletal anchorage sites in the maxilla

Background

The selection of temporary anchorage device (TAD) site can be a challenging task since one should not only consider the 2-D distances between roots, but also the entire 3-D space. Thus, the aim of this study was to evaluate the posterior maxillary region areas available for the insertion of temporary anchorage devices in reconstructed images from cone beam computed tomography (CBCT).

Material and Methods

Sample consisted of 72 patients with indication for orthodontic treatment, grouped into three distinct age groups: 11 to 14 years (age group 1), 15 to 19 years (age group 2) and aged 20 years or older (age group 3), which were further subdivided as to the type of malocclusion (Angle Class I, II and III). Orthopantomographic reconstructions and cross sections were obtained with the Dolphin Imaging software. The distance between the roots of maxillary teeth (canines, premolars and first molars) was determined at 5 mm of the cementoenamel junction, as well as the depth of bone availability at different insertion angles (90°, 75°, 60°, 45°). The influence of different angulations, age, and malocclusion on bone availability was evaluated by ANOVA, followed by the Bonferroni post-test. For the evaluation of the interaction of these factors, 2-way ANOVA was used.

Results

Bone availability was found to be poor between roots in the molar region. There was a reduction in bone availability with increasing age. With regard to angulations, greater bone availability was found in depth for 45° angulation in the canine and first premolar regions and for angulation of 75° or 90° in the molar region. However, there was no difference between bone availability in the region of the second premolars.

Conclusions

According to applied methodology it can be concluded that the region between canines and premolars accepts better vertical angular variations for TADs insertion.

Key words:Cone-Beam Computed Tomography, Orthodontic Anchorage Procedures.

Symposium: Imaging modalities for drug-related osteonecrosis of the jaw (6), assessment of mandibular metabolism due to long-term administration of an anti-resorptive agent by bone scintigraphy (secondary publication)

It is not yet known why anti-resorptive agent-related osteonecrosis specifically affects the jaw. Here we assessed changes in the bone metabolism of the mandible in response to long-term bisphosphonate (BP) therapy, and we compared the bone metabolism changes of the mandible with those of other bone sites using a quantitative analysis by bone scintigraphy. The region of interest was selected by identifying without an abnormal accumulation of the mandible, humerus, second and fourth lumbar vertebrae, iliac crest, intertrochanteric femur and diaphysis. Bone scintigraphy images were quantified using a value we termed the ‘bone uptake value (BUV)’. In the low-dose bisphosphonate (LBP) group (n = 21), the patients were undergoing osteoporosis treatment with low-dose BP. The high-dose BP (HBP) group consisted of 12 bone metastasis patients undergoing high-dose BP treatment. The Control group was 47 subjects with oral disease who had never been treated with an anti-resorptive agent. Our analyses demonstrated that with long-term BP administration, the bone metabolism of the iliac crest and intertrochanteric femur was suppressed but that of the mandible was enhanced. There was no significant difference in bone metabolism with either the low-dose BP or high-dose BP treatment. The effects of the long-term administration of BP were site-specific.

Mechanical adaptation of trabecular bone morphology in the mammalian mandible

Alveolar bone, together with the underlying trabecular bone, fulfils an important role in providing structural support against masticatory forces. Diseases such as osteoporosis or periodontitis cause alveolar bone resorption which weakens this structural support and is a major cause of tooth loss. However, the functional relationship between alveolar bone remodelling within the molar region and masticatory forces is not well understood. This study investigated this relationship by comparing mammalian species with different diets and functional loading (Felis catus, Cercocebus atys, Homo sapiens, Sus scrofa, Oryctolagus cuniculus, Ovis aries). We performed histomorphometric analyses of trabecular bone morphology (bone volume fraction, trabecular thickness and trabecular spacing) and quantified the variation of bone and tooth root volumes along the tooth row. A principal component analysis and non-parametric MANOVA showed statistically significant differences in trabecular bone morphology between species with contrasting functional loading, but these differences were not seen in sub-adult specimens. Our results support a strong, but complex link between masticatory function and trabecular bone morphology. Further understanding of a potential functional relationship could aid the diagnosis and treatment of mandibular diseases causing alveolar bone resorption, and guide the design and evaluation of dental implants.

Assessment of cephalometric characteristics in the elderly

This cross-sectional study aimed at assessing the cephalometric characteristics in the elderly, taking into account differences between genders, age ranges, ethnic groups and dental aspects. The sample consisted of 250 elderly subjects of both genders (163 female, mean age: 68 yr.; 87 male: 70.4 yr.). Conventional lateral cephalograms for cephalometric analysis were scanned and analyzed by Dolphin Imaging software 11.5. The statistical treatment of the data evaluated the influence of gender and age range variables (independent t test), as well as ethnic group, facial profile, and dental characteristics (one-way ANOVA), on cephalometric measurements. A confidence interval of 95% and level of significance of 5% were considered for all the tests performed. The results revealed: 1) The cephalometric measurements evaluated showed significantly lower values for the female gender; 2) a significant decrease in the cephalometric values was observed in relation to the growth pattern, with the advancement of age; 3) significant cephalometric differences were observed between the ethnic groups and the facial profiles; 3) dentulous patients had greater absolute values for all the components evaluated, followed by the individuals with partial dental losses and by those who were edentulous. It may be concluded that the cephalometric alterations observed in this study are inherent to facial maturity, and that they represent specific characteristics regarding each of the variables evaluated. These modifications must be taken into account when planning the treatment for younger patients, to minimize the modifications arising from the natural aging process.

Anatomic Study of the Dorsalis Pedis Artery, First Metatarsal Artery, and Second Metatarsal Bone for Mandibular Reconstruction

PURPOSE

The purpose of this study was to clarify the anatomic variation of the dorsalis pedis and first metatarsal arteries and to define the trabecular-to-cortical bone ratio (TBR) of the second metatarsal bone to ascertain their suitability as implants.

MATERIALS AND METHODS

Fifty-two specimens were prepared for this study. Each specimen was dissected on the dorsal side of the foot to search for the dorsalis pedis artery.

RESULTS

Three types of dorsalis pedis artery were found: in type A, which was the most common, the artery continuously formed the first metatarsal artery; in type C, which was the second most common, the artery coursed below the first dorsal interosseous muscle; and in type B, the artery coursed from the lateral side. Five variations of the first metatarsal artery were identified: the most common was type IIb, in which the artery coursed below the first dorsal interosseous muscle; followed by type Ib, in which the artery coursed obliquely through the muscle; type Ic, in which the artery coursed parallel to the muscle; type IIa, in which the artery coursed above and below the muscle; and type Ia, in which the artery coursed only above the muscle. The second metatarsal bone was divided into 5 regions. There was no trabecular bone in regions 1 and 5. The TBR appeared to be lower in region 3 than in regions 2 and 4 and highest in region 2.

CONCLUSION

All regions of the second metatarsal bone appear to be suitable as implants, but when placing the implant in the proximal end, care should be taken not to overheat the bone and to be wary of perforation when placing it on the middle side.

Real-time thermographic analysis of low-density bone during implant placement: a randomized parallel-group clinical study comparing lateral condensation with bone drilling surgical technique

OBJECTIVES

To compare the effect of two surgical techniques, lateral condensation and bone drilling, on changes in temperature of the adjacent low-density bone during implant placement into posterior maxilla and to investigate the influence of the host factors - age, gender, region of implantation, bone density, and thickness of the cortical bone at the recipient sites.

MATERIAL AND METHODS

Local bone temperature was measured thermographically during implant placement into posterior maxilla following lateral bone condensing (test group) or bone drilling (controls). The main study outcomes were baseline bone temperature prior to implantation and maximum bone temperature recorded during implantation. Early implant success was evaluated after 6 months of healing.

RESULTS

A total of 40 implants were randomly allocated to test and control groups and placed into maxillary premolar and/or molar region of 18 participants of both genders and average age of 51.74 years. All recorded bone temperatures were below the threshold for thermal necrosis. Although both groups showed significant increase in bone temperature during implant placement procedure (P ≤ 0.0005), it was significantly higher for bone condensing compared with drilling (P ≤ 0.0005; 3.79 ± 1.54°C; 1.91 ± 0.70°C respectively). No host factor was singled out as a significant predictor of bone temperature changes, although trend of higher increase was observed in young patients, regardless of gender, during implant placement procedure into maxillary first premolar region with bone density type 3 and cortical layer thicker than 1 mm. Early implant success rate after 6 months follow-up was 100%.

CONCLUSION

Although both surgical techniques, bone condensing and bone drilling, can be considered safe regarding their thermal effect on the bone of posterior maxilla, bone drilling is associated with fewer local bone heating during implantation. Host factors do not affect the bone thermal changes significantly.