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Background: Clinicians needed to be aware of the thinness of the palatal bone plate when identifying severe protrusion of maxillary incisors, as this could result in perforation of the palatal bone plate during surgical procedures associated with immediate maxillary implant placement. Purpose: This study evaluated the thickness of the palatal bone plate, the buccolingual angulation of maxillary incisors, and the correlation between these two parameters in relation to immediate implant placement. Materials and Methods: Cone‐beam computed tomography images of 37 Asian patients (20‐60 years old) with no evidence of dental treatment in the maxillary incisor area were collected and classified into groups based on sex and incisor locations. Sagittal slices were used to measure the palatal bone plate thickness at the cervical, middle, and apical levels, and the buccolingual angulation of each tooth was also measured. The intraclass correlation, Shapiro‐Wilk test, descriptive analysis, Student's t‐test, and Pearson correlation were used for statistical and correlation analyses, with P < .05 applied as the criterion for statistical significance. Results: At the apical level of all inspected teeth and the middle level of lateral incisors, the palatal bone was significantly thicker in males than in females. The inclination of the maxillary lateral incisor showed a moderate negative linear correlation with the palatal bone thickness at the apical level (R = −0.517 and R = −0.579 for males and females, respectively). Conclusions: In an Asian population, an increased buccolingual angulation of the maxillary lateral incisors was correlated with a thinner palatal bone plate at the apical level. [ABSTRACT FROM AUTHOR]

Background Dental implants have become reliable and predictable tools for treating missing teeth. The survival rate of dental implants is markedly influenced by the host bone quality and quantity of the jawbone. A better host bone provides higher initial stability of the dental implant, resulting in better osseointegration and a higher success rate. Host bone quality and quantity are determined by the crestal cortical bone thickness and inner cancellous bone density. Objective The purpose of this study was to determine the crestal cortical bone thickness at dental implant sites in different regions of the jawbone through the use of dental cone-beam computed tomographic (CBCT) images. Materials and Methods A total of 661 dental implant sites (81 in the anterior mandible, 122 in the anterior maxilla, 224 in the posterior mandible, and 234 in the posterior maxilla) were obtained from the jawbones of 173 humans. The data were subjected to statistical analysis to determine any correlation between crestal cortical bone thicknesses and jawbone regions using one-way analysis of variance with Tukey's post-test. Results The crestal cortical bone thicknesses at dental implant sites in the four regions decreased in the following order: posterior mandible (1.07 ± 0.47 mm, mean ± SD) >anterior mandible (0.99 ± 0.36 mm) >anterior maxilla (0.82 ± 0.30 mm) >posterior maxilla (0.75 ± 0.35 mm). Conclusion The dental CBCT data demonstrate that crestal cortical bone thickness varies markedly between dental implant sites in the four regions of the jawbone. [ABSTRACT FROM AUTHOR]

ABSTRACT Purpose: This study investigated how the primary stability of a dental implant as measured by the insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ) is affected by varying thicknesses of cortical bone and strengths of trabecular bone using synthetic bone models. Materials and Methods: Four synthetic cortical shells (with thicknesses of 0, 1, 2, and 3 mm) were attached to four cellular rigid polyurethane foams (with elastic moduli of 137, 47.5, 23, and 12.4 MPa) and one open-cell rigid polyurethane foam which mimic the osteoporotic bone (with an elastic modulus 6.5 MPa), to represent the jawbones with various cortical bone thicknesses and strengths of trabecular bone. A total of 60 bone specimens accompanied with implants was examined by a torque meter, Osstell resonance frequency analyzer, and Periotest electronic device. All data were statistically analyzed by two-way analysis of variance. In addition, second-order nonlinear regression was utilized to assess the correlations of the primary implant stability with the four cortex thicknesses and five strengths of trabecular bone. Results: ITV, ISQ, and PTV differed significantly ( p < .05) and were strongly correlated with the thickness of cortical bone ( R2 > 0.9) and the elastic modulus of trabecular bone ( R2 = 0.74-0.99). Conclusions: The initial stability at the time of implant placement is influenced by both the cortical bone thickness and the strength of trabecular bone; however, these factors are mostly nonlinearly correlated with ITV, PTV, and ISQ. Using ITV and PTV seems more suitable for identifying the primary implant stability in osteoporotic bone with a thin cortex. [ABSTRACT FROM AUTHOR]

Background Lysyl oxidase (LOX) is a copper-dependent enzyme that cross-links collagen and elastin in the extracellular matrix. LOX overexpressed in various tumors. The manner in which LOX affects tumor growth remains controversial. Methods Chemical treatment and gene transfection were used to induce LOX overexpression or inhibition in cell lines SAS and SVEC4-10. LOX mRNA, protein, and activity were confirmed before tube formation assay and tumorigenesis. The microvessels in the tumor section were detected by immunostaining CD31-positive endothelial cells. Results LOX overexpression and copper induction of LOX activity increased SVEC4-10 tube formation. LOX silencing and β-aminopropionitrile inhibition of LOX activity had opposite effects. LOX overexpression increased proliferation and proliferating cell nuclear antigen expression. High LOX expression clones increased tumor size in a tumorigenesis model. The microvascular numbers were higher in LOX overexpression tumors than in control tumors. Conclusion LOX can induce cell proliferation and angiogenesis in oral squamous cell carcinoma. © 2012 Wiley Periodicals, Inc. Head Neck, 2013 [ABSTRACT FROM AUTHOR]

Objective The purpose of this study was to determine the relationships and differences in three-dimensional (3D) bone mineral density ( BMD) and microtrabecular structures between autogenous bone grafts and their adjacent native bone after a healing period following maxillary sinus augmentation. Materials and methods Nine rod-shaped human bone biopsy samples were taken from patients receiving two-stage sinus augmentation therapy in implantation areas and analyzed using microcomputed tomography (micro- CT). Before micro- CT scanning, two BMD phantoms were placed near to the bone biopsy samples for executing BMD calculations of the grafted and native bone samples. In addition, 3D structural parameters of the trabeculae were analyzed for both the grafted and native bone, including percentage of bone volume [bone volume ( BV)/tissue volume ( TV)], bone-specific surface [bone surface ( BS)/ BV], trabecular thickness ( Tb. Th), trabecular number ( Tb. N), trabecular separation ( Tb. Sp), trabecular pattern factor ( Tb. Pf), and structure model index ( SMI). Results No significant correlations with regard to BMD and trabecular-structure parameters were found between native bone and grafted bone; however, BS/ BV and Tb. Pf were higher and Tb. Th and Tb. Sp were 37.35% and 12.74% lower in grafted bone than in native bone. For grafted bone, there were significant correlations ( P < 0.05) between BMD and BV/ TV, and Tb. N. Conclusions When using autogenous bone as a graft material, BMD and micromorphological conditions of grafted bone were not influenced by the condition of the native bone in the maxilla. Differences were found in surface complexity, trabecular thickness, trabecular separation, and the connectivity of trabeculae between grafted and native bone. The BMD in grafted bone was affected by the quantity of the trabeculae. [ABSTRACT FROM AUTHOR]

The aim of this study was to evaluate the effects of cortical bone thickness and trabecular bone elastic modulus on the strain in the bone surrounding an immediately loaded implant. We also examined the correlations between bone structure and the following indices of primary implant stability: insertion torque value (ITV), Periotest value (PTV), and implant stability quotient (ISQ). The ITV, PTV, and ISQ were measured in 24 artificial jaw bone models representing cortical bone with four thicknesses (0, 1, 2, and 3 mm) and trabecular bone with four elastic moduli (137, 47.5, 23, and 12.4 MPa). Two loading conditions were applied (force of 130 N applied vertically and at 45° laterally), and the strains in the crestal region were measured by rosette strain gauges with a data acquisition system. When the cortical bone thickness and the elastic modulus of trabecular bone decreased, the bone strains increased by 10.3-52.1% and 39-73.1%, respectively, for vertical loading and by 35-62% and 42.4-56.2% for lateral loading. The cortical bone thickness has a stronger correlation ( R=0.95-0.71) with ITV, PTV, and ISQ than the elastic modulus of trabecular bone ( R=0.89-0.59). The initial stability at the time of implant placement is influenced by both the cortical bone thickness and the elastic modulus of trabecular bone; however, these parameters are not totally linearly correlated with ITV, PTV, and ISQ. The placement of an immediately loaded implant in cases with thin cortical bone and/or weak trabecular bone can induce extreme bone strains and may increase the risk of implant failure. Huang H-L, Chang Y-Y, Lin D-J, Li Y-F, Chen K-T, Hsu J-T. Initial stability and bone strain evaluation of the immediately loaded dental implant: an in vitro model study. Clin. Oral Impl. Res. , 2011; 691-698 doi: 10.1111/j.1600-0501.2010.01983.x [ABSTRACT FROM AUTHOR]

Three-dimensional finite element (FE) models of splinted prosthetic crowns were studied and stress analyses were evaluated with different types of implant support, including standard, wide or two implant(s) for partial, posterior edentulous restorations. The FE models were constructed based on a cadaver mandible containing the 2nd premolar and the 1st molar. The crowns of these two teeth were modeled as connected and disconnected to mimic the splinted and non-splinted designs, respectively. One standard implant was placed at the premolar region, while three types of implant support, one at a time (the standard implant, wide implant and two implants), were used to support the molar crown. A 100 N oblique load was applied to the buccal cusp on each crown. The FE simulation was validated experimentally via strain gauge measurement. The experimental data were well correlated with the FE predictions ( r2=0.97). When compared with the standard implant used in the molar area, the wide implant and two implants reduced the peak stress in crestal bone by 29–37% for both splinted and non-splinted cases. Inserting the standard implant into both the premolar and molar area, the bone stresses were identical for splinted and non-splinted designs. However, splinting the adjacent crowns has shown to decrease the bone stresses at the premolar region by 25%, while the wide implant or two implants were placed at the molar region. The biomechanical advantages of using the wide implant or two implants are almost identical. The benefit of load sharing by the splinted crowns is notable only when the implants on the premolar and molar regions have different supporting ability. [ABSTRACT FROM AUTHOR]