Maxillary Bone Density Research Articles

How does orthodontic tooth movement influence the dental pulp? RNA-sequencing on human premolars.

The objective of this study is to analyse the gene expression profile of the dental pulp (DP) of human premolars subjected to 7 and 28 days of orthodontic force (OF) in vivo by using RNA sequencing. The maxillary and mandibular DP were additionally compared. Healthy patients requiring orthodontic premolar extractions were randomly assigned to one of the three groups: control (CG) where no OF was applied, 7 and 28 days, where premolars were extracted either 7 or 28 days after the application of a 50-100 g OF. Total RNA was extracted from the DP and analysed via RNA-seq. Differentially expressed genes (DEGs) were identified using a false discovery rate and fold change threshold of <0.05 and ≥1.5, respectively. Functional analysis was performed. After 7 days of OF, pulp reaction indicates immune response, hypoxia, DNA damage and epigenetic regulation. After 28 days, cell adhesion, migration, organization and tissue repair are evident. The maxillary and mandibular pulp tissues react differently to OF. The maxilla exhibits minimal alterations, mostly related to immune response at 7 days and tissue repair at 28 days, whereas the mandible shows mostly DNA damage and epigenetic regulation at 7 days and return to the original state at 28 days. This study demonstrates that the early reaction of the DP to OF is marked by immune response, hypoxia and DNA damage. In contrast, after 28 days, cell adhesion, migration, organization, tissue repair and dentine formation are observed. Maxillary and mandibular premolars react differently to OF: although the maxilla exhibits minimal alterations at both time points, the mandible mostly shows DNA damage, epigenetic regulation, and immune response at 7 days. These disparities could stem from different blood supplies or the lower maxillary bone density, potentially triggering faster biological changes. Our findings provide insights into the gene regulatory networks modulating DP response to OF.

Effects of tooth loss on anxiety‐like behaviors in Heterocephalus glaber

Tooth loss is an ailment affecting a large percentage of the population, particularly individuals of lower socioeconomic status and the elderly. Extensive tooth loss is known to result in anatomical changes in the face, including atrophy of masticatory muscles and decreases in mandibular and maxillary bone density, as well as volumetric changes within the brain. Human studies have reported strong correlations between tooth loss and levels of both anxiety and depression. However, little has been reported to date regarding the effect of dental health on emotional states, with only sparse information available from animal models regarding the psychiatric effects of tooth loss.Our study investigated the short‐term effects of tooth loss on anxiety‐like behaviors using Heterocephalus glaber, an animal with extensive sensory dedication to and behavioral reliance on its incisors. Adult naked mole‐rats underwent either tooth extraction or sham surgeries, followed by testing in both an open field maze and elevated plus maze in the weeks following. As there are no known studies to date that have utilized this animal model in behavioral tests of anxiety, our study provides critical information about the methodologies and modifications necessary to ascertain these important translational behavioral states so that future researchers can apply similar tests in other fields such as neurodegeneration, aging, and oncology.We hypothesized that tooth extraction will result in greater anxiety‐like behaviors, manifesting in various ways: greater defecation in the mazes, more time spent in the outer regions of the open field maze, and less time in the open arms of the elevated plus maze. The study demonstrated a trend towards tooth extraction increasing anxiety‐like behaviors in naked mole‐rats when investigated using the open field maze paradigm. There is evidence that, with an increase in sample sizes, this research will make evident the causal relationship of tooth loss and anxiety. Future research will investigate the long‐term behavioral changes associated with extensive tooth loss and the neurocircuitry associated with these behavioral alterations. Uncovering these details will provide potential therapeutic targets for negating the mental health difficulties associated with deficits in dental health.

Evaluation of maxillary canine root and maxillary bone thickness and density in patients with displaced maxillary canines: A cone-beam tomography study

This study investigated lateral incisor and canine morphology and dimensions, maxillary bone density, and volume in subjects with displaced maxillary canines. Cone-beam computed tomography images for 134 palatally displaced canines (PDCs), 57 buccally displaced canines (BDCs), and 87 nondisplaced canines (NDCs) were analyzed. Canine and lateral incisor dimensions, alveolar bone dimensions, and maxillary bone volume and density were measured. The root length of BDCs was short compared with NDC and PDC groups. The lateral incisor was short in the PDC group compared with NDC and BDC groups. In the BDC group, maxillary bone volume was reduced compared with NDCs and PDCs. Significant differences were detected between BDC and PDC groups in bone density buccal to canines and between BDC and NDC groups in bone density distal to canines. The density of maxillary bone was the highest in the PDC group and the lowest in the BDC group compared with the NDC group. Eight variables were associated with the site of maxillary canine displacement: lateral incisor tip, alveolar bone density, alveolar bone width, bone density buccal to canine, canine width labiopalatally, maxillary bone volume, and canine midsagittal width. In PDCs, the maxillary lateral incisor was short, the canine root had a larger crown/root ratio, and maxillary bone volume was increased compared with NDCs. In BDCs, the canine root was shorter than NDCs and PDCs, maxillary bone volume was reduced compared with NDCs, and bone density at the buccal side was reduced compared with the PDC group.

Deflection of mini implants from its intended path of placement on varying bone densities.

Knowledge of bone density in maxilla and mandible will allow the clinician to plan the anchorage strategies and placement of implants with necessary precautions. The study aims to evaluate the deflection changes of titanium alloy self-drilling mini implants from the intended path that occurs during placement in varying bone densities. 63 titanium alloy self-drilling mini implants of the lengths 6mm, 8mm, and 10mm with diameter of 1.3mm were placed in three homogenous solid rigid polyurethane foam (saw bone) with bone densities of 20pcf, 30pcf, and 40pcf simulating anatomic sites in maxilla and mandible. 7mini implants of each length in all bone densities were tested for study. The implants were inserted perpendicularly into artificial bone block held in a custom made stand. The bone blocks were then radiographically exposed and the deviation of the long axis of the implantfrom a true vertical line was measured. There was a decrease in deflection of the mini implant with increase in density. On the other hand, increase in length resulted in increase in the amount of deflection. Longer mini implants can be used in less dense bone as in maxilla, whereas shorter mini implants can be used in high dense bone as in mandible to increase the stability and success rate of implants. Bone density and implant length play a role in deflection of mini implant from its intended path of insertion. Key words:Orthodontic Mini implants, deflection, bone density, anchorage.

Computed tomography assessment of maxillary bone density for orthodontic mini-implant placement with respect to vertical growth patterns.

To quantitatively measure and report bone density of maxilla in the interradicular (alveolar and basal bone) and infrazygomatic crest (IZC) region in various growth patterns among Dravidian individuals. This was a retrospective spiral computed tomography (CT) study. The study was conducted at the Department of Orthodontics, Saveetha Dental College and Hospital, Tamil Nadu, India. Sixty CT scans (24 men, 36 women; mean age = 25.3 years and 23.8 years, respectively) divided equally into three groups based on vertical facial proportions were included. Bone density measurements in Hounsfield units (HU) were performed using Philips and RadiAnt DICOM viewers. Buccal cortical, palatal cortical and cancellous bone regions were analysed in a Philips DICOM viewer and IZC region was analysed in a RadiAnt DICOM viewer. Statistical analysis with one-way ANOVA and post-hoc Tukey HSD test was done. The hypodivergent group had a significantly higher bone density at the buccal cortex in posterior region (P < 0.05) when compared to the normodivergent and hyperdivergent groups. Buccal basal bone was denser than buccal alveolar bone (P < 0.05) in all three groups. In the IZC region, hypodivergent groups had significantly higher density values when compared to the normodivergent and hyperdivergent groups (P < 0.05). The present study concluded that cancellous bone density in the interradicular regions was greatest in the anterior sites and was not influenced by growth pattern. Hypodivergent groups tend to have higher density in the posterior regions (buccal and palatal cortical bone) and at the IZC region compared to normodivergent and hyperdivergent groups.

A Computed Tomographic Assessment of Osteitis of Sinus Bony Structures in Horses With Sinonasal Disorders.

Background: Computed tomographic (CT) imaging has shown some horses with sinonasal diseases to have changes in their sinus bony structures. Scintigraphic and clinical evidence of sinus osteitis have also been reported. However, no study has objectively examined for the presence and degree of osteitis in equine sinonasal disease.Objectives: To assess for the presence and extent of osteitis of sinus-related bony structures by examination of CT images of horses with clinically and sinoscopically confirmed unilateral sinonasal disease.Study Design: Retrospective examination of CT images of horses with confirmed, mainly chronic (>2 month duration) unilateral sinus disease of different etiologies.Methods: Bone thickness at designated sites of the maxillary bone (n = 3), frontal bone (n = 1), infraorbital canal (n = 2), and bony nasolacrimal duct (n = 1) were measured, as were the maximal diameters of the infraorbital canal and the bony nasolacrimal duct on both affected and control sides. Maxillary bone density (in Hounsfield Units) was also assessed bilaterally. Bone thickness was compared between affected and controlled sides using paired statistical tests.Results: Bone was significantly thicker in the affected sinuses compared to the control sides at the three maxillary bone sites (all, P < 0.001) and at both infraorbital bone sites (both, P < 0.001), but not at the two most dorsal sites examined, i.e. frontal bone (P = 0.188) and bony nasolacrimal duct (P = −0.260) sites. Infraorbital canal and bony nasolacrimal duct diameters were significantly wider in the affected as compared to the control sides (P < 0.001 and P = 0.002, respectively). Maxillary bone density did not differ significantly between the affected (mean = 1,075 HU, SD = 230.01) and control (mean = 1,100, SD = 200.71) sides (t(58) = −1.03, P = 0.306).Main Limitations: Possible variation in selecting measurement sites. Variation in the severity and chronicity of sinonasal disease between horses.Conclusions: Osteitis and enlargement of paranasal bony structures commonly occurs in horses with sinonasal disease and can explain the clinical presence of ipsilateral diffuse soft tissue facial swelling, epiphora, and scintigraphic evidence of bone inflammation in sinonasal disease.

Alveolar Cortical Bone Density among Different Facial Types: A CBCT Study

Aim: To evaluate and compare the cortical bone density amongst skeletally Class I individuals with different facial forms using Cone Beam Computer Tomography (CBCT). Materials and Methods: Cross-sectional study was conducted using pre-treatment CBCT records of 45 patients, 15 each of hyperdivergent, normodivergent and hypodivergent facial pattern categories selected from the institutional archives. Median bone density was assessed in anterior and posterior sites of maxilla and mandible, followed by comparison of data between hypodivergent, normodiveregent and hyperdivergent subjects. The inter-group statistical comparison of continuous variables was done using Kruskal-Wallis H test. Intra-group statistical comparison of continuous variables was done using Mann-Whitney U test. Results: Median anterior bone density in maxilla and mandible were relatively similar across the 03 facial patterns (P&gt;0.05). However, buccal cortical bone density was increased in normodivergent and hypodivergent subjects compared to hyperdivergent subjects, which was statistically significant (P&lt;0.05). It was also noticed in this study that the density of left buccal region was higher when compared to right which was statistically significant (P&lt;0.05), across 3 facial patterns. Conclusion: This study concludes that hyperdivergent subjects have relatively less dense bones in both maxilla and mandible as compared to other facial patterns. Clinically, it is advised to place wider diameter and increased length TADs in these subjects for better initial and long term stability. However, long term prospective studies with a larger sample size are required to validate the findings of these studies.

Analysis of bone density in a group of patients with dental inclusion

Background/Aim: Genetic and environmental etiologic factors have been described for maxillary canine impaction, except for the trabecular bone characteristics in the impacted area. The aim of this study was to evaluate the surface area and bone density using cone-beam computed tomography (CBCT) images of patients with maxillary impacted canines. Material and Methods: The sample comprised preorthodontic treatment, CBCT images of 24 participants with unilateral maxillary impacted canines, using the impacted side as study group and the non-impacted side as control group. CBCT images were acquired in portrait mode (17 x 23 cm high field of view) at 120 kV, 5 mA, 8.9 seconds exposure time, and 0.3 mm voxel size. Each root was divided into three levels (cervical, intermediate, and apical) to determine whether the bone density change varied with the tooth level. Moreover, each level was divided into four regions (palatal, distal, mesial, and buccal sides). Bone density was measured using Hounsfield Units. Comparisons were made using paired t tests and linear regression. Repeated measurements were obtained randomly from about 20% of the sample. Results: In subjects with unilateral impactions, the maxillary bone density was higher in the impacted side, with a mean difference of 350 HU. Bone density increases in the corono-apical direction of about 100 HU in the impaction site and about 50 HU in the site of the erupted canine. The repeated measurements showed similar results. Conclusions: The maxillary alveolar bone area and bone density are increased in the impacted side compared with the nonimpacted side.

Alveolar bone density and its clinical implication in the placement of dental implants and orthodontic mini-implants.

Objectives:To assess the bone density in maxilla and mandible in dentate and edentulous patients in Saudi population.Methods:This study involved a retrospective analysis of cone beam CT images of 100 patients (50 male and 50 female) who have come to College of Dentistry, University of Dammam, Dammam, Kingdom of Saudi Arabia between January 2014 and 2015. Using the bone density option in the Simplant software, the Hounsfield unit (HU) was calculated at the edentulous sites. While for dentate sites, a region of interest was selected coronally at 3-5 mm to the root apex using I-CAT vision software. The densities of the buccal bone and cancellous bone were measured at interradicular areas of a specific teeth.Results:The highest bone density at the edentulous sites was at the mandibular anterior region (776.5 ± 65.7 HU), followed by the mandibular posterior region (502.2 ± 224.2 HU). Regarding the dentate sites, the highest bone density was at the buccal cortical plate of the lower incisor teeth (937.56 ± 176.92 HU) and the lowest bone density was at the cancellous bone around the posterior maxillary teeth (247.12 ± 46.75 HU).Conclusion:The alveolar bone density at dentate and edentulous sites in our population is generally lower than the norm reference density of other populations, which dictates the need for quantitative assessment of bone density before implants and mini-implants placement.

Evaluating Maxilla Bone Quality Through Clinical Investigation of Voxel Grey Scale Values from Cone-Beam Computed Tomography for Dental Use.

During the study the relative bone density thickness in maxilla was evaluated in 20 patients. The aim of the study was to investigate relative bone density in maxilla by means of voxel value measurements. The study comprised of 20 patients in whom cone beam computed tomography scans were made for diagnostic purposes. The horizontal scans of the maxilla were used for analysis. The measurements of density of both cortical plates and trabecular bone were taken in interdental spaces. To eliminate negative values a modified grey scale was introduced in which radiological density of the air was determined as "0". For every patient relative bone density was calculated separately for anterior and posterior maxilla. Mean values of relative radiological density for cortical plates and trabecular bone were 0.849 for palatal cortical plate, 0.8978 for vestibular cortical plate and 0.5988 for trabecular bone in anterior maxilla with standard deviation (SD) 0.0931 - 0.0971 - 0.1091 respectively. In posterior maxilla the mean values were 0.5274 for palatal cortical plate, 0.6047 for vestibular cortical plate and 0.3307 for trabecular bone with SD 0.1635 - 0.1515 - 0.126 respectively. The statistically significant difference (p < 0.001) was found for radiological density of dental alveolus in anterior and posterior maxilla. The mean of radiological densities of vestibular cortical plate is higher than that of palatal cortical plate. The mean radiological density of trabecular bone is × 2 lower than the mean radiological density of vestibular cortical plate in posterior region and × 1.5 lower in anterior region of the maxilla. The clinical use of CBCT radiological bone density measurement tool with modified grey scale voxel values creates possibility to evaluate the relative bone density of dental alveolus.

Estrogen Deficiency-Associated Bone Loss in the Maxilla: A Methodology to Quantify the Changes in the Maxillary Intra-radicular Alveolar Bone in an Ovariectomized Rat Osteoporosis Model.

The effects of estrogen deficiency on bone characteristics are site-dependent, with the most commonly studied sites being appendicular long bones (proximal femur and tibia) and axial bones (vertebra). The effect on the maxillary and mandibular bones is still inconsistent and requires further investigation. This study was designed to evaluate bone quality in the posterior maxilla of ovariectomized rats to validate this site as an appropriate model to study the effect of osteoporotic changes. Forty-eight 3-month-old female Sprague-Dawley rats were randomly divided into two groups: an ovariectomized (OVX) group (n=24) and Sham-operated (SHAM) group (n=24). Six rats were randomly sacrificed from both groups at time points 8, 12, 16, and 20 weeks. The samples from tibia and maxilla were collected for micro computed tomography (μCT) and histological analysis. For the maxilla, the volume of interest area focused on the furcation areas of the first and second molar. Trabecular bone volume fraction (BV/TV, %), trabecular thickness (Tb.Th.), trabecular number (Tb.N.), trabecular separation (Tb.Sp.), and connectivity density (Conn.Dens) were analyzed after Micro CT scanning. At 8 weeks the indices BV/TV, Tb.Sp., Tb.N., and Conn.Dens showed significant differences (p<0.05) between the OVX and SHAM groups in the tibia. Compared with the tibia, the maxilla developed osteoporosis at a later stage, with significant changes in maxillary bone density only occurring after 12 weeks. Compared with the SHAM group, both the first and second molars of the OVX group showed significantly decreased BV/TV values from 12 weeks, and these changes were sustained through 16 and 20 weeks. For Tb.Sp., there were significant increases in bone values for the OVX group compared with the SHAM group at 12, 16, and 20 weeks. Histological changes were highly consistent with Micro CT results. This study established a method to quantify the changes of intra-radicular alveolar bone in the posterior maxilla in an accepted rat osteoporosis model. The degree of the osteoporotic changes to trabecular bone architecture is site-dependent and at least 3 months are required for the osteoporotic effects to be apparent in the posterior maxilla following rat OVX.

Relation between Spongy Bone Density in the Maxilla and Skeletal Bone Density.

Osteoporosis is a disease affecting more than 300 million people worldwide and is responsible for numerous medical complications. This study aimed to investigate the relation between skeletal and maxillary bone density. Seventy-three patients were recruited and divided between group A (osteoporosis), group B (healthy, control), and group C (osteopenia) on the basis of a dual-energy x-ray absorptiomery (DXA) scan. These patients also received a CT scan on which bone density measurements were performed at five sites: maxilla midline, retromolar tuberosities, incisor, premolars, and molar regions. The bone density was lower in osteoporotic patients compared with the control patients. The bone mineral density (BMD) of the tuberosities showed the strongest correlations with the BMD of the hip and the spine (respectively, r = 0.50 and r = 0.61). The midline region showed moderate correlations with the hip (r = 0.47) and the spine (r = 0.46). For potential implant sites, the correlations with the BMD of the hip and spine were, however, small to insignificant. Based on measurements of bone density of the maxilla, it was possible to predict if the patient was osteoporotic or not with a sensitivity of 65% and a specificity of 83%. The maxillary bone density of subjects with osteoporosis is significantly lower than that of healthy patients. Moreover, there is a direct correlation between the density of the skeleton and the density of some sites of the maxilla. Using measurements of maxillary bone density in order to predict skeletal bone density might be a useful tool for the screening of osteoporosis.

Osteoporosis detection using intraoral densitometry

To determine the diagnostic accuracy of mandibular and maxillary bone density in detecting osteoporosis using receiver operating characteristic (ROC) analysis. 671 women between 45 years and 70 years of age underwent dual energy X-ray absorptiometry (DXA) of the hip and lumbar spine. This was the gold standard for diagnosing osteoporosis. Intraoral radiography of the upper and lower right premolar region was performed, using an aluminium wedge as a densitometric reference. Jaw bone density was determined using dedicated software. Observer differences and ROC curves were analysed. For detecting osteoporosis using jaw bone density, the area under the ROC curve (A(z)) was 0.705. For separate analysis of mandibular and maxillary films, sensitivity varied from 33.9% to 38.7% and specificity from 83.5% to 85.3% when using a threshold of 4.3 mm Al equivalent. Density of the premolar region reaches a fair diagnostic accuracy, which might improve when including additional factors in the analysis and refining the densitometric tool.

Surgical intervention in enchondral and membranous bone: intraindividual comparisons in the rabbit.

The long bones, which are of enchondral origin, are often used in histologic evaluations of dental implants that clinically will be placed in bones of membranous origin. The aim of this investigation was to study the effect of surgical trauma by multiple drill perforations on both enchondral and membranous bone--the tibial and maxillary bone architecture--8 weeks after surgery. In eight rabbits the medial metaphyses of both tibiae and the edentulous ridges of both sides in the maxilla were surgically exposed. On the test sides, 25 to 30 holes were drilled through the cortical plate and 5 mm into the medullary space. The contralateral sides underwent no treatment and served as controls. Eight weeks later the animals were killed to obtain transverse ground sections for histomorphometry. A paired analysis of the bone densities of the tibiae and the jaw specimens was made. In general the morphologic appearances of the test and control tibiae were similar. In the control group the anatomy of the medullary space appeared normal, with few bone trabeculae and with abundant marrow tissue. In the test group, areas of resorption were evident on the cortical bone plate that had been perforated 8 weeks previously; also evident were ingrowths of marrow tissue and bone formation. In a few specimens some newly formed bone trabeculae were found in the medullary space, both contiguous to the perforated cortical bone plate and as small islets in the marrow tissue. The mean test and control site values for each parameter were similar, and no statistically significant differences were found. In the maxilla, the bone architecture had altered substantially by way of an increase in the proportion of trabecular bone and a decrease in the proportion of cortical bone. Drilling appeared to have little effect on tibial bone density, which did not significantly differ between test and control sites. Maxillary bone density, however, was significantly greater at the test sites than at the control sites. Comparisons of bone density between tibia and jaw specimens revealed no significant differences either between test sides or between control sides. Thus, the same magnitude of surgical trauma that altered the bone architecture and density of the rabbit maxilla was not found to have altered those of the tibia in the same animal 8 weeks after surgery. The reasons for the differences are discussed in this article. As observed 8 weeks post surgery, multiple drill perforations were not found to cause significant alterations in the metaphysis of the tibia whereas a considerable change in bone architecture and an increase in bone density were found in the maxilla. Whether this depends on different embryologic origins or reflects morphologic and functional differences in the mature bone demands further study.

Incisor Adaptation to Fossorial Life in the Blind Mole-Rax Spalax ehrenbergi

Blind mole-rats (Spalax ehrenbergi) are aggressive and solitary fossorial rodents, highly specialized to their environment. They use their lower incisors mainly to excavate their tunnel systems. We found that the lower incisors of the mole-rat grow significantly faster than the upper incisors. Upper and lower incisors of males grow significantly faster than incisors of females. Density of incisors of males was significantly higher than in females and in male laboratory rats (Rattus norvegicus). In both sexes of mole-rats, maxillary bone density at the root apex area of the incisor was significantly higher than the anterior area where incisors emerge from the bone and the same area densities in male laboratory rats. We suggest that the rapid growth rate and high density of incisors in mole-rats compared with male laboratory rats represent an adaptation to their digging life-style and compensate for the extensive incisor attrition resulting from the mechanical forces of digging. Inter-sexual differences in mole-rat incisor growth and incisor plus maxillary bone densities are in accordance with intersexual behavioral differences: males excavate wider and longer tunnels than females and are more aggressive. Because incisors of males are used more extensively in digging and fighting than those of females, we suggest that male mole-rats develop stronger incisors with a higher compensatory growth rate than females.