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Bone Quantity (bone + quantity)
Selected AbstractsAccuracy of Linear Measurement Provided by Cone Beam Computed Tomography to Assess Bone Quantity in the Posterior Maxilla: A Human Cadaver StudyCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 4 2008Sophie Veyre-Goulet DDS ABSTRACT Purpose: The aim of this study was to assess, for implant placement in the posterior maxilla, the accuracy of linear measurements provided by cone beam computed tomography (CBCT) using an image intensifier tube and television (TV) chain as an X-ray detector despite a loss of contrast resolution. The NewTom® 9000 (Quantitative Radiology, Verona, Italy) was used to explore the posterior maxilla. Materials and Methods: Fourteen measurements were taken in three dry maxillaries. On every anatomical site, three fiducial markers were placed on the bony crest to define a plane. Dry maxillaries were submitted to CBCT imaging examination. The maxillaries were then sawn according to the previously defined planes, and bone height and width were assessed using a caliper. The same measurements were taken on images. Results: Clinical analysis demonstrated no difference between real measurements and image measurements. Conclusions: Although cadaver bone density may not correspond to the density of vital bone, this in vitro study indicates that CBCT images provided by technique using image intensifier tube and TV chain as an X-ray detector are reliable to define the bone volume of the posterior maxilla for the purpose of planning the implant axis. [source] Exercise When Young Provides Lifelong Benefits to Bone Structure and Strength,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2007Stuart J Warden PT Abstract Short-term exercise in growing rodents provided lifelong benefits to bone structure, strength, and fatigue resistance. Consequently, exercise when young may reduce the risk for fractures later in life, and the old exercise adage of "use it or lose it" may not be entirely applicable to the skeleton. Introduction: The growing skeleton is most responsive to exercise, but low-trauma fractures predominantly occur in adults. This disparity has raised the question of whether exercised-induced skeletal changes during growth persist into adulthood where they may have antifracture benefits. This study investigated whether brief exercise during growth results in lifelong changes in bone quantity, structure, quality, and mechanical properties. Materials and Methods: Right forearms of 5-week-old Sprague-Dawley rats were exercised 3 days/week for 7 weeks using the forearm axial compression loading model. Left forearms were internal controls and not exercised. Bone quantity (mineral content and areal density) and structure (cortical area and minimum second moment of area [IMIN]) were assessed before and after exercise and during detraining (restriction to home cage activity). Ulnas were removed after 92 weeks of detraining (at 2 years of age) and assessed for bone quality (mineralization) and mechanical properties (ultimate force and fatigue life). Results: Exercise induced consistent bone quantity and structural adaptation. The largest effect was on IMIN, which was 25.4% (95% CI, 15.6,35.3%) greater in exercised ulnas compared with nonexercised ulnas. Bone quantity differences did not persist with detraining, whereas all of the absolute difference in bone structure between exercised and nonexercised ulnas was maintained. After detraining, exercised ulnas had 23.7% (95% CI, 13.0,34.3%) greater ultimate force, indicating enhanced bone strength. However, exercised ulnas also had lower postyield displacement (,26.4%; 95% CI, ,43.6% to ,9.1%), indicating increased brittleness. This resulted from greater mineralization (0.56%; 95% CI, 0.12,1.00%), but did not influence fatigue life, which was 10-fold greater in exercised ulnas. Conclusions: These data indicate that exercise when young can have lifelong benefits on bone structure and strength, and potentially, fracture risk. They suggest that the old exercise adage of "use it or lose it" may not be entirely applicable to the skeleton and that individuals undergoing skeletal growth should be encouraged to perform impact exercise. [source] Genetically Based Influences on the Site-Specific Regulation of Trabecular and Cortical Bone Morphology,JOURNAL OF BONE AND MINERAL RESEARCH, Issue 4 2004Stefan Judex Abstract The degree of site-specificity by which genes influence bone quantity and architecture was investigated in the femur of three strains of mice. Morphological indices were highly dependent on both genetic makeup as well as anatomical location showing that the assessment of bone structure from a single site cannot be extrapolated to other sites even within a single bone. Introduction: The identification of genes responsible for establishing peak BMD will yield critical information on the regulation of bone quantity and quality. Whereas such knowledge may eventually uncover novel molecular drug targets or enable the identification of individuals at risk of osteoporosis, the site-specificity by which putative genotypes cause low or high bone mass (and effective bone morphology) is essentially unknown. Materials and Methods: ,CT was used to determine morphological and microarchitectural features of the femora harvested from three genetically distinct strains of 4-month-old female mice, each with distinct skeletal mass (low: C57BL/6J [B6], medium: BALB/cByJ [BALB], high: C3H/HeJ [C3H]). Two trabecular regions (distal epiphysis and metaphysis) were considered in addition to four cortical regions within the metaphysis and diaphysis. Results and Conclusions: Comparing morphological properties of the different trabecular and cortical femoral regions between the three strains of mice, it was apparent that high or low values of specific parameters of bone morphology could not be consistently attributed to the same genetic strain. Trabecular metaphyseal bone volume, for instance, was 385% larger in C3H mice than in B6 mice, yet the two strains displayed similar bone volume fractions in the epiphysis. Similarly, BALB mice had 48% more trabecular bone than C3H mice in the epiphysis, but there were no strain-specific differences in cortical bone area at the diaphysis. These data suggest that the genetic control of bone mass and morphology, even within a given bone, is highly site-specific and that a comprehensive search for genes that are indicative of bone quantity and quality may also have to occur on a very site-specific basis. [source] Quantity and Quality of Trabecular Bone in the Femur Are Enhanced by a Strongly Anabolic, Noninvasive Mechanical InterventionJOURNAL OF BONE AND MINERAL RESEARCH, Issue 2 2002Clinton Rubin Ph.D. Abstract The skeleton's sensitivity to mechanical stimuli represents a critical determinant of bone mass and morphology. We have proposed that the extremely low level (<10 microstrain), high frequency (20-50 Hz) mechanical strains, continually present during even subtle activities such as standing are as important to defining the skeleton as the larger strains typically associated with vigorous activity (>2000 microstrain). If these low-level strains are indeed anabolic, then this sensitivity could serve as the basis for a biomechanically based intervention for osteoporosis. To evaluate this hypothesis, the hindlimbs of adult female sheep were stimulated for 20 minutes/day using a noninvasive 0.3g vertical oscillation sufficient to induce approximately 5 microstrain on the cortex of the tibia. After 1 year of stimulation, the physical properties of 10-mm cubes of trabecular bone from the distal femoral condyle of experimental animals (n = 8) were compared with controls (n = 9), as evaluated using microcomputed tomography (,CT) scanning and materials testing. Bone mineral content (BMC) was 10.6% greater (p < 0.05), and the trabecular number (Tb.N) was 8.3% higher in the experimental animals (p < 0.01), and trabecular spacing decreased by 11.3% (p < 0.01), indicating that bone quantity was increased both by the creation of new trabeculae and the thickening of existing trabeculae. The trabecular bone pattern factor (TBPf) decreased 24.2% (p < 0.03), indicating trabecular morphology adapting from rod shape to plate shape. Significant increases in stiffness and strength were observed in the longitudinal direction (12.1% and 26.7%, respectively; both, p < 0.05), indicating that the adaptation occurred primarily in the plane of weightbearing. These results show that extremely low level mechanical stimuli improve both the quantity and the quality of trabecular bone. That these deformations are several orders of magnitude below those peak strains which arise during vigorous activity indicates that this biomechanically based signal may serve as an effective intervention for osteoporosis. [source] Early Complete Failures of Fixed Implant-Supported Prostheses in the Edentulous Maxilla: A 3-Year Analysis of 17 Consecutive Cluster Failure PatientsCLINICAL IMPLANT DENTISTRY AND RELATED RESEARCH, Issue 2 2006Odont Dr/PhD, Torsten Jemt DDS ABSTRACT Background, Clusters of implant failures in the edentulous maxilla seem to occur in some patients. To create groups for analysis with higher numbers of these patients implies large original groups for inclusion. Purpose, The aim of this study was to retrospectively describe and compare a group of "cluster failure patients" with randomly selected patients treated in the edentulous maxilla. Materials and Methods, From a group of 1,267 consecutively treated patients in one clinic, all patients presenting failing fixed implant-supported prostheses within the first 3 years of follow-up were included. All patients were treated with turned titanium implants using two-stage surgery. A control group of equal number of patients were created for comparison. Data on patients were retrospectively retrieved from their records, and compared. Results, Seventeen patients (1.3%) met the inclusion criteria in the entire group. The bone resorption index revealed less bone quantity in the study group (p < .05) during implant placement, but there was no difference regarding primary implant stability at first-stage surgery. The distribution of short and long implants showed relatively higher number of short implants in the study group (p < .05), and more patients had a presurgical discussion on the risk of implant failure prior to treatment in this group (p < .05). Only 5 out of 102 implants (4.9%) were lost before prosthesis placement as compared to 38 and 25 lost implants during the following two years in the study group. Smoking habits and signs of bone loss related to periodontitis in the lower dentition were more frequent in the study group, but did not reach a significant level (p > .05). Conclusion, The results indicate that bone quantity, reflected in fixture length, has a significant impact on increased implant failure risk. Other factors of interest as predictors for implant failures could be smoking habits and also possibly signs of periodontitis in the opposing dentition. [source] Long-term, retrospective evaluation (implant and patient-centred outcome) of the two-implant-supported overdenture in the mandible.CLINICAL ORAL IMPLANTS RESEARCH, Issue 5 2010Part 2: marginal bone loss Abstract Objective: In part 2 of this long-term, retrospective study on the two-implant-supported overdenture in the mandible, the annual marginal bone loss was evaluated in detail and parameters, with a significant effect on the annual bone loss, were verified. Material and methods: For all 495 patients with an overdenture in the mandible at least 5 years in function, data up to their last follow-up visit had been collected, including long-cone radiographs (taken at the abutment connection and after years 1, 3, 5, 8, 12 and 16 of loading) and probing data at their last evaluation. General information (medical history, implant data, report on surgery) was retrieved from the patient's file. Two hundred and forty-eight patients had been clinically examined recently. For the others, information on bone level and probing depths were retrieved from the patient's files, as all patients had been enrolled in our annual follow-up schedule. Results: The mean annual bone loss on a site level (without considering the first year of bone remodelling) after 3 years of loading was 0.08 mm/year (SD=0.22, n=1105), after 5 years of loading 0.07 mm/year (SD=0.14, n=892), after 8 years of loading 0.06 mm/year (SD=0.12, n=598), after 12 years 0.04 mm/year (SD=0.07, n=370) and 0.05 mm/year (SD=0.05, n=154) after 16 years of loading. Ongoing bone loss was seen in a number of implants (n=26) with the annual bone loss exceeding 0.2 mm. Some factors clearly showed a significant impact on bone loss: smoking (,10 cigarettes/day), GBR, the presence of dehiscence and bone quantity(the latter only during the first year). The probing data showed a favourable condition, with <1.2% of the approximal pockets being ,6 mm, and 4.1%=5 mm. Conclusions: The mean annual bone loss over the study period was <0.1 mm/year after the first year of loading. However, a small number (2.5%) of the implants showed continuing bone loss. To cite this article: Vercruyssen M, Quirynen M. Long-term, retrospective evaluation (implant and patient-centred outcome) of the two-implants-supported overdenture in the mandible. Part 2: marginal bone loss. Clin. Oral Impl. Res. 21, 2010; 466,472. doi: 10.1111/j.1600-0501.2009.01902.x [source] | ||||||||||