Mesiobuccal Root Canal Morphology of Maxillary First Molars in a Brazilian Sub-Population - A Micro-CT Study.

Objective: This study aimed to investigate the root canal system morphology of maxillary first molar mesiobuccal (MB) roots in a Brazilian sub-population using micro-computed tomography. Methods: Ninety-six MB roots were scanned with a micro-CT (Skyscan 1173, Bruker). Three-dimensional images were analyzed regarding the number of pulp chamber orifices, the number and classification of the canals, the presence of accessory canals in different thirds of the root as well as the number and type of apical foramina. Results: A single entrance orifice was found in 53.0% of the samples, two in 43.9% and only 3.1% had three orifices. The second mesiobuccal root canal (MB2) was present at some portion of the root in 87.5% of the specimens. A single apical foramen was present in 16.7%, two in 22.9%, and three or more foramina in 60.4% of the roots. Only 55.3% and 76.1% of the root canals could be arranged by Weine's and Vertucci's classifications, respectively. Conclusion: The number of orifices at the pulp chamber level could not work as a predictor of the MB2 presence. The most prevalent canal configuration was Weine type IV / Vertucci type V. The anatomical complexity of the MB root could not be entirely classified by the current most accepted classifications.

Impact of Weight Loss With Intragastric Balloon on Bone Density and Microstructure in Obese Adults.

The historical concept that obesity protects against bone fractures has been questioned. Weight loss appears to reduce bone mineral density (BMD); however, the results in young adults are inconsistent, and data on the effects of weight loss on bone microstructure are limited. This study aimed to evaluate the impact of weight loss using an intragastric balloon (IGB) on bone density and microstructure. Forty obese patients with metabolic syndrome (mean age 35.1 ± 7.3 yr) used an IGB continuously for 6 mo. Laboratory tests, areal BMD, and body composition measurements via dual-energy X-ray absorptiometry, and volumetric BMD and bone microstructure measurements via high-resolution peripheral quantitative computed tomography were conducted before IGB placement and after IGB removal. The mean weight loss was 11.5%. After 6 mo, there were significant increases in vitamin D and carboxyterminal telopeptide of type 1 collagen levels. After IGB use, areal BMD increased in the spine but decreased in the total femur and the 33% radius. Cortical BMD increased in the distal radius but tended to decrease in the distal tibia. The observed trabecular bone loss in the distal tibia contributed to the decline in the total volumetric BMD at this site. There was a negative correlation between the changes in leptin levels and the measures of trabecular quality in the tibia on high-resolutionperipheral quantitative computed tomography. Weight loss may negatively impact bone microstructure in young patients, especially for weight-bearing bones, in which obesity has a more prominent effect.

Influence of Heat Treatment of Nickel-Titanium Rotary Endodontic Instruments on Apical Preparation: A Micro-Computed Tomographic Study.

INTRODUCTION: The aim of this study was to make a 3-dimensional comparison of the canal transportation and changes in apical geometry using micro-computed tomographic imaging after canal preparation with K3 (SybronEndo, Orange, CA) and K3XF (SybronEndo) file systems. METHODS: Twenty-eight mandibular molars were randomly divided into 2 groups according to the rotary system used in instrumentation: K3 or K3XF. The specimens were scanned by micro-computed tomographic imaging before and after instrumentation. Images before and after instrumentation from each group were compared with regard to canal volume, surface area, and structure model index (SMI) (paired t test, P < .05). After instrumentation, the canals from each group were compared regarding the changes in volume, surface area, SMI, and canal transportation in the last 4 apical mm (t test, P < .05). RESULTS: Instrumentation with the 2 rotary systems significantly changed the canal volume, surface area, and SMI (P < .05). There were no significant differences between instrument types concerning these parameters (P > .05). There were no significant differences between the 2 groups with regard to canal transportation in the last 4 apical mm (P > .05). CONCLUSIONS: Both rotary systems showed adequate canal preparations with reduced values of canal transportation. Heat treatment did not influence changes in root canal geometry in the apical region.

Bone density and microarchitecture in endogenous hypercortisolism.

OBJECTIVE: Osteoporosis is a serious and underestimated complication of endogenous hypercortisolism that results in an increased risk of fractures, even in patients with normal or slightly decreased bone mineral density (BMD). Alterations in bone microarchitecture, a very important component of bone quality, may explain bone fragility. The aim of this study was to investigate bone density and microarchitecture in a cohort of patients with endogenous Cushing's syndrome (CS). DESIGN: Cross-sectional study. PATIENTS: Thirty patients with endogenous active CS and fifty-one age-, sex- and body mass index-matched controls were included. MEASUREMENTS: Participants were studied for areal BMD (dual-energy X-ray absorptiometry) of the lumbar spine (LS), femoral neck (FN), total femur (TF) and radius (33%), and for volumetric bone density (vBMD) and structure using high-resolution peripheral quantitative computed tomography (HR-pQCT) of the distal radius and distal tibia. RESULTS: Patients with active CS exhibited lower areal BMD and Z-score values in the LS, FN and TF (P < 0·003 for all comparisons). At HR-pQCT, the patients with CS also had lower cortical area (P = 0·009 at the radius and P = 0·002 at the tibia), lower cortical thickness (P = 0·02 at the radius and P = 0·002 at the tibia), lower cortical density (P = 0·008 at the tibia) and lower total vBMD (P = 0·002 at the tibia). After the exclusion of hypogonadal individuals, the patients with CS maintained the same microarchitectural and densitometric alterations described above. CONCLUSIONS: Endogenous hypercortisolism has deleterious effects on bone, especially on cortical bone microstructure. These effects seem to be a more important determinant of bone impairment than gonadal status.

Lean mass as a predictor of bone density and microarchitecture in adult obese individuals with metabolic syndrome.

The effects of obesity and metabolic syndrome (MS) on bone health are controversial. Furthermore, the relationship between body composition and bone quality has not yet been determined in this context. The aim of this study was to investigate the correlations between body composition and bone mineral density (BMD) and bone microstructure in obese individuals with MS. This cross-sectional study assessed 50 obese individuals with MS with respect to their body composition and BMD, both assessed using dual X-ray absorptiometry, and bone microarchitecture, assessed by high-resolution peripheral quantitative computed tomography (HR-pQCT) of the distal tibia and radius. Several HR-pQCT measurements exhibited statistically significant correlations with lean mass. Lean mass was positively correlated with parameters of better bone quality (r: 0.316-0.470) and negatively correlated with parameters of greater bone fragility (r: -0.460 to -0.310). Positive correlations were also observed between lean mass and BMD of the total femur and radius 33%. Fat mass was not significantly correlated with BMD or any HR-pQCT measurements. Our data suggest that lean mass might be a predictor of bone health in obese individuals with MS.

Bone metabolism in obese rats programmed by early weaning.

OBJECTIVE: Obesity and osteoporosis seem to have a common pathogenesis, especially because bone and adipose tissue have common origins. Since early weaning (EW) decreases adipogenesis and osteogenesis in neonate, further programming for obesity and hyperleptinemia, we hypothesized that these changes in adipogenesis could affect bone metabolism. MATERIALS/METHODS: Lactating rats were separated into 3 groups: control - dams whose pups ate milk throughout lactation; mechanical EW (MEW) - dams were involved with a bandage interrupting suckling in the last 3days of lactation; pharmacological EW (PEW) - dams were bromocriptine-treated (0.5mg/twice a day via intraperitoneal injection) 3days before weaning. The adult offspring was subjected to dual-energy X-ray absorptiometry and bone tissue was also evaluated by computed tomography, microcomputed tomography and biomechanical tests, beyond serum analyses. RESULTS: MEW and PEW presented higher total bone mineral density (BMD), total bone mineral content, spine BMD and bone area in postnatal day 150 (PN150). In PN180, both groups also presented increase of these parameters and higher femur BMD and fourth lumbar vertebra (LV4) BMD, femoral head radiodensity and LV4 vertebral body radiodensity, trabecular number, stiffness and break load; lower trabecular separation, maximal deformation and break deformation, and also hyperleptinemia and higher visceral fat mass and 25-hydroxivitamin D, whereas parathyroid hormone was unchanged. Serum C-terminal cross-linked telopeptide of type I collagen was lower for both groups. CONCLUSIONS: Since both models program for obesity and increased bone mass, and leptin increases plasma vitamin D levels, probably leptin is the link between obesity and higher bone mass.

Late adherent human bone marrow stromal cells form bone and restore the hematopoietic microenvironment in vivo.

Bone marrow stromal cells (BMSCs) are a valuable resource for skeletal regenerative medicine because of their osteogenic potential. In spite of the very general term "stem cell," this population of cells is far from homogeneous, and different BMSCs clones have greatly different phenotypic properties and, therefore, potentially different therapeutic potential. Adherence to a culture flask surface is a primary defining characteristic of BMSCs. We hypothesized that based on the adherence time we could obtain an enriched population of cells with a greater therapeutic potential. We characterized two populations of bone marrow-derived cells, those that adhered by three days (R-cells) and those that did not adhere by three days but did by six days (L-cells). Clones derived from L-cells could be induced into adipogenic, chondrogenic, and osteogenic differentiation in vitro. L-cells appeared to have greater proliferative capacity, as manifested by larger colony diameter and clones with higher CD146 expression. Only clones from L-cells developed bone marrow stroma in vivo. We conclude that the use of late adherence of BMSCs is one parameter that can be used to enrich for cells that will constitute a superior final product for cell therapy in orthopedics.

Acromegaly has a negative influence on trabecular bone, but not on cortical bone, as assessed by high-resolution peripheral quantitative computed tomography.

INTRODUCTION: Acromegaly is one of the causes of secondary osteoporosis, although studies of bone mineral density (BMD) have yielded conflicting results and none of them have evaluated the bone properties. OBJECTIVES AND PATIENTS: Our objective was to correlate, in a cohort of 82 acromegalic patients, BMD and bone microarchitecture, using dual-energy x-ray absorptiometry and high-resolution peripheral quantitative computed tomography, with the presence of type 2 diabetes mellitus (T2DM), disease activity, and gonadal status and to compare these bone parameters between 45 eugonadal acromegalic patients and 45 healthy controls. RESULTS: Acromegalic patients with T2DM had lower trabecular density and trabecular bone volume to tissue volume ratio in the distal tibia. Patients with active acromegaly exhibited a higher BMD and T-score in the lumbar spine (P = .02 for both) and a higher cortical density in the distal tibia when compared with those with controlled acromegaly (P = .001). After multiple linear regression (including age, presence of T2DM, acromegaly activity, and gonadal status), eugonadism remained the main determinant of bone parameters. The 45 acromegalic patients with eugonadism were compared with 45 age- and sex-matched controls and exhibited lower trabecular densities and impaired microstructures. CONCLUSIONS: Acromegaly appears to have a deleterious effect on trabecular bone microarchitecture, and in this specific population, the gonadal status might be more important than T2DM or acromegaly activity in determining bone health. High-resolution peripheral quantitative computed tomography seems promising for evaluating acromegalic bone properties and for addressing the limitations posed by dual-energy x-ray absorptiometry.