Low serum 25-hydroxyvitamin D levels, tooth loss, and the prevalence of severe periodontitis in Koreans aged 50 years and older

Purpose@#Vitamin D deficiency may cause bone loss and increased inflammation, which are well-known symptoms of periodontal disease. This study investigated whether serum 25-hydroxyvitamin D (25(OH)D) levels are associated with periodontal disease status and tooth loss. @*Methods@#Cross-sectional data from 5,405 individuals aged ≥50 years (2,253 males and 3,152 females) were obtained from the 2008–2010 Dong-gu study, a prospective cohort study of risk factors for chronic diseases. Periodontal examinations were conducted to evaluate the number of remaining teeth, the periodontal probing depth (PPD), the clinical attachment level (CAL), and bleeding on probing. The percentages of sites with PPD ≥4 mm and CAL ≥4 mm were recorded for each participant. The severity of periodontitis was classified using the Centers for Disease Control and Prevention and the American Academy of Periodontology case definitions.Serum 25(OH)D levels were classified as reflecting severe deficiency, deficiency, insufficiency, or sufficiency. Multivariate linear regression analysis was performed to assess the associations of serum 25(OH)D levels with periodontal parameters and the number of remaining teeth after adjusting for confounders including age, smoking status, alcohol consumption status, month of blood collection, and physical activity. Multivariate logistic regression was used to evaluate the association between serum vitamin D levels and severe periodontitis. An overall statistical analysis and a stratified analysis by sex were performed. @*Results@#Overall, the rates of severe deficiency, deficiency, insufficiency, and sufficiency were 6.5%, 67.9%, 22.4%, and 3.2%, respectively. After adjustment for confounders, vitamin D levels were directly associated with the number of remaining teeth, an association that was significant in males, but not in females. Sufficient serum 25(OH)D was associated with a low frequency of severe periodontitis. @*Conclusions@#This population-based cross-sectional study indicates that low serum 25(OH) D is significantly associated with tooth loss and severe periodontitis in Koreans aged 50 years and older.

Effects of implant alignment and load direction on mandibular bone and implant: finite element analysis

Purpose@#To evaluate the effects of load direction, number of implants, and alignment of implant position on stress distribution in implant, prosthesis, and bone tissue. @*Materials and Methods@#Four 3D models were made to simulate posterior mandible bone block: two implants and 3-unit fixed dental prosthesis (FDP) with a pontic in the center (model M1), two implants and 3-unit FDP with a cantilever pontic at one end (model M2), FDP supported by three implants with straight line placement (model M3) and FDP supported by three implants with staggered implant configuration (model M4). The applied force was 120 N axially or 120 N obliquely. @*Results@#Peak von Mises stresses caused by oblique occlusal force were 3.4 to 5.1 times higher in the implant and 3.5 to 8.3 times higher in the alveolar bone than those stresses caused by axial occlusal force. In model M2, the connector area of the distal cantilever in the prosthesis generated the highest von Mises stresses among all models. With the design of a large number of implants, low stresses were generated. When three implants were placed, there were no significant differences in the magnitude of stress between staggered arrangement and straight arrangement. @*Conclusion@#The effect of staggering alignment on implant stress was negligible. However, the number of implants had a significant effect on stress magnitude.

Low serum 25-hydroxyvitamin D levels, tooth loss, and the prevalence of severe periodontitis in Koreans aged 50 years and older

Purpose@#Vitamin D deficiency may cause bone loss and increased inflammation, which are well-known symptoms of periodontal disease. This study investigated whether serum 25-hydroxyvitamin D (25(OH)D) levels are associated with periodontal disease status and tooth loss. @*Methods@#Cross-sectional data from 5,405 individuals aged ≥50 years (2,253 males and 3,152 females) were obtained from the 2008–2010 Dong-gu study, a prospective cohort study of risk factors for chronic diseases. Periodontal examinations were conducted to evaluate the number of remaining teeth, the periodontal probing depth (PPD), the clinical attachment level (CAL), and bleeding on probing. The percentages of sites with PPD ≥4 mm and CAL ≥4 mm were recorded for each participant. The severity of periodontitis was classified using the Centers for Disease Control and Prevention and the American Academy of Periodontology case definitions.Serum 25(OH)D levels were classified as reflecting severe deficiency, deficiency, insufficiency, or sufficiency. Multivariate linear regression analysis was performed to assess the associations of serum 25(OH)D levels with periodontal parameters and the number of remaining teeth after adjusting for confounders including age, smoking status, alcohol consumption status, month of blood collection, and physical activity. Multivariate logistic regression was used to evaluate the association between serum vitamin D levels and severe periodontitis. An overall statistical analysis and a stratified analysis by sex were performed. @*Results@#Overall, the rates of severe deficiency, deficiency, insufficiency, and sufficiency were 6.5%, 67.9%, 22.4%, and 3.2%, respectively. After adjustment for confounders, vitamin D levels were directly associated with the number of remaining teeth, an association that was significant in males, but not in females. Sufficient serum 25(OH)D was associated with a low frequency of severe periodontitis. @*Conclusions@#This population-based cross-sectional study indicates that low serum 25(OH) D is significantly associated with tooth loss and severe periodontitis in Koreans aged 50 years and older.

Effects of implant alignment and load direction on mandibular bone and implant: finite element analysis

Purpose@#To evaluate the effects of load direction, number of implants, and alignment of implant position on stress distribution in implant, prosthesis, and bone tissue. @*Materials and Methods@#Four 3D models were made to simulate posterior mandible bone block: two implants and 3-unit fixed dental prosthesis (FDP) with a pontic in the center (model M1), two implants and 3-unit FDP with a cantilever pontic at one end (model M2), FDP supported by three implants with straight line placement (model M3) and FDP supported by three implants with staggered implant configuration (model M4). The applied force was 120 N axially or 120 N obliquely. @*Results@#Peak von Mises stresses caused by oblique occlusal force were 3.4 to 5.1 times higher in the implant and 3.5 to 8.3 times higher in the alveolar bone than those stresses caused by axial occlusal force. In model M2, the connector area of the distal cantilever in the prosthesis generated the highest von Mises stresses among all models. With the design of a large number of implants, low stresses were generated. When three implants were placed, there were no significant differences in the magnitude of stress between staggered arrangement and straight arrangement. @*Conclusion@#The effect of staggering alignment on implant stress was negligible. However, the number of implants had a significant effect on stress magnitude.

Stress distribution in premolars restored with inlays or onlays: 3D finite element analysis

PURPOSE: To analyze stress distribution in premolars restored with inlays or onlays using various materials. MATERIALS AND METHODS: Three-dimensional maxillary premolar models of abutments were designed to include the following: 1) inlay with O cavity (O group), 2) inlay with MO cavity (MO group), 3) inlay with MOD cavity (MOD group), and 4) onlay (ONLAY group). A restoration of each inlay or onlay cavity was simulated using gold alloy, e.max ceramic, or composite resin for restoration. To simulate masticatory forces, a total of 140 N static axial force was applied onto the tooth at the occlusal contact areas. A finite element analysis was performed to predict the magnitude and pattern of stresses generated by occlusal loading. RESULTS: Maximum von Mises stress values generated in the abutment teeth of the ONLAY group were ranged from 26.1 to 26.8 MPa, which were significantly lower than those of inlay groups (O group: 260.3–260.7 MPa; MO group: 252.1–262.4 MPa; MOD group: 281.4–298.8 MPa). Maximum von Mises stresses generated with ceramic, gold, and composite restorations were 280.1, 269.9, and 286.6 MPa, respectively, in the MOD group. They were 252.2, 248.0, 255.1 MPa, respectively, in the ONLAY group. CONCLUSION: The onlay design (ONLAY group) protected tooth structures more effectively than inlay designs (O, MO, and MOD groups). However, stress magnitudes in restorations with various dental materials exhibited no significant difference among groups (O, MO, MOD, ONLAY).

Stress distribution of implants with external and internal connection design: a 3-D finite element analysis

PURPOSE: This study aims to analyze the stress distribution of mandibular molar restoration supported by the implants with external hex and internal taper abutment connection design. MATERIALS AND METHODS: Models of external connection (EXHEX) and internal connection (INCON) implants, corresponding abutment/crowns, and screws were developed. Supporting edentulous mandibular bony structures were designed. All the components were assembled and a finite element analysis was performed to predict the magnitude and pattern of stresses generated by occlusal loading. A total of 120 N static force was applied both by axial (L1) and oblique (L2) direction. RESULTS: Peak von Mises stresses produced in the implants by L2 load produced 6 – 15 times greater than those by L1 load. The INCON model showed 2.2 times greater total amount of crown cusp deflection than the EXHEX model. Fastening screw in EXHEX model and upside margin of implant fixture in INCON model generated the peak von Mises stresses by oblique occlusal force. EXHEX model and INCON model showed the similar opening gap between abutment and fixture, but intimate sealing inside the contact interface was maintained in INCON model. CONCLUSION: Oblique force produced grater magnitudes of deflection and stress than those by axial force. The maximum stress area at the implant was different between the INCON and EXHEX models.

Taurine ameliorates hyperglycemia and dyslipidemia by reducing insulin resistance and leptin level in Otsuka Long-Evans Tokushima fatty (OLETF) rats with long-term diabetes

This study aimed to determine whether taurine supplementation improves metabolic disturbances and diabetic complications in an animal model for type 2 diabetes. We investigated whether taurine has therapeutic effects on glucose metabolism, lipid metabolism, and diabetic complications in Otsuka Long-Evans Tokushima fatty (OLETF) rats with long-term duration of diabetes. Fourteen 50-week-old OLETF rats with chronic diabetes were fed a diet supplemented with taurine (2%) or a non-supplemented control diet for 12 weeks. Taurine reduced blood glucose levels over 12 weeks, and improved OGTT outcomes at 6 weeks after taurine supplementation, in OLETF rats. Taurine significantly reduced insulin resistance but did not improve beta-cell function or islet mass. After 12 weeks, taurine significantly decreased serum levels of lipids such as triglyceride, cholesterol, high density lipoprotein cholesterol, and low density lipoprotein cholesterol. Taurine significantly reduced serum leptin, but not adiponectin levels. However, taurine had no therapeutic effect on damaged tissues. Taurine ameliorated hyperglycemia and dyslipidemia, at least in part, by improving insulin sensitivity and leptin modulation in OLETF rats with long-term diabetes. Additional study is needed to investigate whether taurine has the same beneficial effects in human diabetic patients.

Role of Glucocorticoids in Fasting-induced Changes in Hypothalamic and Pituitary Components of the Growth Hormone (GH)-axis

To directly test if elevated glucocorticoids are required for fasting-induced regulation of growth hormone (GH)-releasing hormone (GHRH), GHRH receptors (GHRH-R) and ghrelin receptors (GHS-R) expression, male rats were bilaterally adrenalectomized or sham operated. After 7 days, animals were fed ad libitum or fasted for 48 h. Bilateral adrenalectomy increased hypothalamic GHRH to 146% and decreased neuropeptide Y (NPY) mRNA to 54% of SHAM controls. Pituitary GHRH-R and GHS-R mRNA levels were decreased by adrenalectomy to 30% and 80% of sham-operated controls. In sham- operated rats, fasting suppressed hypothalamic GHRH (49%) and stimulated NPY (166%) mRNA levels, while fasting increased pituitary GHRH-R (391%) and GHS-R (218%) mRNA levels. However, in adrenalectomized rats, fasting failed to alter pituitary GHRH-R mRNA levels, while the fasting-induced suppression of GHRH and elevation of NPY and GHS-R mRNA levels remained intact. In fasted adrenalectomized rats, corticosterone replacement increased GHRH-R mRNA levels and intensified the fasting-induced decrease in GHRH, but did not alter NPY or GHS-R response. These data suggest that elevated glucocorticoids mediate the effects of fasting on hypothalamic GHRH and pituitary GHRH-R expression, while glucocorticoids are likely not the major determinant in fasting-induced increases in hypothalamic NPY and pituitary GHS-R expression.