Bone Formation Using Cross-Linked Chitosan Scaffolds in Rat Calvarial Defects.

PURPOSE: To investigate the osteoconductive effect of a chitosan scaffold in a rat skull defect model. Previous publications have demonstrated the osteoinductive properties as scaffold materials with growth factors; however, whether chitosan alone has osteoconductive ability is unclear. This study used cross-linked chitosan scaffolds for in vivo evaluation of scaffold-supported bone regeneration in rat calvarial defects using histopathological analysis and examination of alkaline phosphatase (ALP), calcium, phosphorus, and calcitonin serum levels. MATERIALS AND METHODS: Scaffolds were made of cross-linked chitosan. After the defect was filled with the scaffold, the periosteum was carefully repositioned and sutured to stabilize the scaffold. The effects of the scaffold on wound repair were examined microscopically. Morphological radiographic and histopathological analyses of wound repair ratios were performed at 3 and 4 weeks after the defects were made. RESULTS: Using the cross-linked chitosan biomaterial of the wounds. The amount of regenerated bone measured was significantly greater in the chitosan-treated group than in the control group. The ALP level in the chitosan group at 4 weeks was higher than at baseline and at the 4-week follow-up in the control group (P < 0.05). CONCLUSIONS: The results show that cross-linked chitosan has an osteoconductive effect on bone regeneration in vivo.

pH-Dependent spectroscopic and luminescent properties, and metal-ion recognition studies of Re(I) complexes containing 2-(2'-pyridyl)benzimidazole and 2-(2'-pyridyl)benzimidazolate.

A series of Re(I) complexes, [Re(CO)(3)Cl(HPB)] (1), [Re(CO)(3)(PB)H(2)O] (2), [Re(CO)(3)(NO(3))(PB-AuPPh(3))] (3), and [Re(CO)(3)(NO(3))(PB)Au(dppm-H)Au](2) (4) [HPB = 2-(2'-pyridyl)benzimidazole; dppm = 2,2'-bis(diphenylphosphinomethane)], have been synthesized and characterized by X-ray diffraction. Complex 1, which exhibits interesting pH-dependent spectroscopic and luminescent properties, was prepared by reacting Re(CO)(5)Cl with an equimolar amount of 2-(2'-pyridyl)benzimidazole. The imidazole unit in complex 1 can be deprotonated to form the imidazolate unit to give complex 2. Addition of 1 equiv of AuPPh(3)(NO(3)) to complex 2 led to the formation of a heteronuclear complex 3. Addition of a half an equivalent of dppm(Au(NO(3)))(2) to complex 2 yielded 4. In both 3 and 4, the imidazolate unit acts as a multinuclear bridging ligand. Complex 4 is a rare and remarkable example of a Re(2)Au(4) aggregate in combination with µ(3)-bridging 2-(2'-pyridyl)benzimidazolate. Finally, complex 2 has been used to examine the Hg(2+)-recognition event among group 12 metal ions. Its reversibility and selectivity toward Hg(2+) are also examined.

Dental Scaling Decreases the Risk of Parkinson's Disease: A Nationwide Population-Based Nested Case-Control Study.

The protective effect of dental scaling in Parkinson's disease (PD) remains inconclusive. The aim of this study was to analyze the association between dental scaling and the development of PD. A retrospective nested case-control study was performed using the National Health Insurance Research Database of Taiwan. The authors identified 4765 patients with newly diagnosed PD from 2005 to 2013 and 19,060 individuals without PD by matching sex, age, and index year. In subgroup 1, with individuals aged 40⁻69 years, individuals without periodontal inflammatory disease (PID) showed a protective effect of dental scaling against PD development, especially for dental scaling over five consecutive years (adjusted odds ratio = 0.204, 95% CI = 0.047⁻0.886, p = 0.0399). In general, the protective effect of dental scaling showed greater benefit for individuals with PID than for those without PID, regardless of whether dental scaling was performed for five consecutive years. In subgroup 2, with patients aged ≥70 years, the discontinued (not five consecutive years) scaling showed increased risk of PD. This was the first study to show that patients without PID who underwent dental scaling over five consecutive years had a significantly lower risk of developing PD. These findings emphasize the value of early and consecutive dental scaling to prevent the development of PD.

Accuracy of Implant Placement with a Navigation System, a Laboratory Guide, and Freehand Drilling.

PURPOSE: Computer-aided surgery under navigation system guidance is widely applied in dental implant procedures. However, the accuracy of drilling with such navigation systems has not been comparatively evaluated alongside those of laboratory guide-based and freehand drilling. Therefore, this study aimed to compare the accuracies of these three drilling systems. MATERIALS AND METHODS: A navigation system, a laboratory guide, and freehand drilling were used to drill 150 holes on 30 cast models. Two master models-one each for the maxilla and mandible-were prepared with the idea of placing five implants per cast. After drilling five holes on each cast, postoperative cone beam computed tomography images were acquired to measure the magnitude of errors. RESULTS: The navigation system and laboratory guide were more accurate than freehand placement with respect to total errors at the entry and apex, lateral error at the apex, and angular error. The navigation system was more accurate than the laboratory guide with respect to angular error. Laboratory guide-based drilling was more accurate than freehand drilling in terms of lateral error at entry. CONCLUSION: In comparison with the laboratory guide and freehand placement, the navigation system exhibited lower angular and axial errors. Despite its higher accuracy, the navigation system requires the operator to pay greater attention.

Association between chronic periodontitis and the risk of Alzheimer's disease: a retrospective, population-based, matched-cohort study.

BACKGROUND: Although recent short-term cross-sectional studies have revealed that chronic periodontitis (CP) may be a risk factor for increased cognitive impairment in patients with Alzheimer's disease (AD), systematic reviews and long-term longitudinal studies have provided less clear evidence regarding the relationship between CP and AD. Therefore, we conducted a retrospective cohort study using the National Health Insurance Research Database (NHIRD) of Taiwan to determine whether patients with CP are at increased risk of developing AD. METHODS: We conducted a retrospective matched-cohort study using the NHIRD of Taiwan. We identified 9291 patients newly diagnosed with CP between 1997 and 2004. A total of 18,672 patients without CP were matched to the patient cohort according to sex, age, index year, co-morbidity and urbanisation level. Cox proportional hazards regression analyses were performed to evaluate the subsequent risk of AD. RESULTS: Patients with CP had a higher prevalence of hyperlipidaemia, depression, traumatic brain injury and co-morbidities, as well as higher urbanisation levels, than those in the unexposed cohort (all p < 0.01). At the final follow-up, totals of 115 (1.24%) and 208 (1.11%) individuals in the CP exposed and unexposed groups, respectively, had developed AD. Patients with 10 years of CP exposure exhibited a higher risk of developing AD than unexposed groups (adjusted HR 1.707, 95% CI 1.152-2.528, p = 0.0077). CONCLUSIONS: Our findings demonstrate that 10-year CP exposure was associated with a 1.707-fold increase in the risk of developing AD. These findings highlight the need to prevent progression of periodontal disease and promote healthcare service at the national level.

Periodontal inflammatory disease is associated with the risk of Parkinson's disease: a population-based retrospective matched-cohort study.

BACKGROUND: The cause-effect relation between periodontal inflammatory disease (PID) and Parkinson's disease (PD) remains uncertain. The purpose of our study was to investigate the association between PID and PD. METHODS: We conducted a retrospective matched-cohort study by using Taiwan's National Health Insurance Research Database. We identified 5,396 patients with newly diagnosed PID during 1997-2004 and 10,792 cases without PID by matching sex, age, index of year (occurrence of PID), and comorbidity. Cox proportional hazard regression was used to evaluate the risk of subsequent PD. RESULTS: At the final follow-up, a total of 176 (3.26%) and 275 (2.55%) individuals developed PD in the case and control groups, respectively. Patients with PID have a higher risk of developing PD (adjusted hazard ratio = 1.431, 95% CI [1.141-1.794], p = 0.002). DISCUSSION: Our results show that PID is associated with an increased risk of developing PD. Whilst these findings suggest that reducing PID may modify the risk of developing PD, further study will be needed.

Er:YAG Laser for Surgical Crown Lengthening: A 6-Month Clinical Study.

This study evaluated use of a solid-state laser to avoid the flap technique and suturing. An Er:YAG laser was used in 26 consecutive patients referred for osseous crown lengthening in 32 posterior teeth. The distance from the planned restoration margin to the alveolar crest (B) satisfied a 3-mm dentogingival complex. No tissue necrosis and no significant change in the distance from the gingival margin to B or probing depth were detected at 3 and 6 months. Minimally invasive Er:YAG laser surgery decreases the time needed to establish the gingival margin necessary for definitive restoration.