Solubility of TTCP and β-TCP by solid titration

Objective

Using solid titration with hydroxyapatite (HAp) and octacalcium phosphate, HAp has been found to be more stable than dicalcium phosphate dihydrate (DCPD) even at lower pH, inconsistent with the widely reported view that DCPD is less soluble than other calcium phosphates below pH 4.2. A check of the behaviour of other calcium phosphates (TTCP; Ca/P: 2.00 and β-TCP; Ca/P: 1.33) is necessary.

Methods

Solid titration was used to determine the effective solubility of TTCP and β-TCP in 100 mM KCl solution at 37.0 ± 0.1 °C for pH ∼2.9-9.2 and ∼3-7.4 respectively. The constitution of the precipitate was determined by XRD, particle morphology was observed by SEM and TEM, and the precipitate Ca/P ratio was calculated by EDX.

Results

The only identified solid phase at equilibrium was HAp at both pH 3.60 and 4.50; no residual titrant or other phases were detected. A marked change of slope in the curve occurred at pH ∼3.9 for TTCP.

Conclusion

HAp was verified to be more stable than other calcium phosphates, especially at lower pH. That DCPD is more stable below pH 4.2 is contradicted.     

Instructions for Authors by China Journal of Oral and Maxillofacial Surgery

China Journal of Oral and Maxillofacial Surgery (CJOMS)(ISSN 1672-3244), founded in November 8 2002, is an official journal of ChineseSociety of Oral and Maxillofacial Surgery, being designed to present the latest basic scientific and clinical findings of Oral and Maxillofacial Surgery inChina. It is published quarterly currently by Editorial Board of China Journal of Oral and Maxillofacial Surgery.     

Plasma rich in growth factors promote gingival tissue regeneration by stimulating fibroblast proliferation and migration and by blocking transforming growth factor-β1-induced myodifferentiation

Background: Periodontitis involves inflammation and infection of the ligaments and bones that support the teeth. Gingival fibroblasts are the most abundant cells in periodontal tissue, and they play a role in maintaining the structural integrity of the tissue. Plasma rich in growth factors contain a pool of proteins and growth factors that promote wound healing and tissue regeneration. In the present study, we evaluate the potential of different formulations obtained with this approach to stimulate several biologic processes involved in wound healing, including fibroblast proliferation, migration, adhesion, and the autocrine release of some angiogenic factors and extracellular matrix components. Furthermore, the ability of this technology to prevent and inhibit transforming growth factor β1‐induced myodifferentiation was also determined. Methods: Cell proliferation was evaluated through a colorimetric assay, cell migration was performed on culture inserts, and cell adhesion was studied through a fluorescence‐based method. Enzyme‐linked immunosorbent assay was used to determine some of the biomolecules released by gingival fibroblasts. Smooth muscle actin expression was assessed through immunofluorescence microscopy. Results: Results showed that plasma rich in growth factors significantly increased gingival fibroblast proliferation, migration, and cell adhesion on type I collagen matrix. In addition, it stimulated the autocrine expression of vascular endothelial growth factor, hepatocyte growth factor, and hyaluronic acid. The myofibroblast phenotype, which is characterized by expressing α‐smooth muscle actin, was inhibited and reverted by treating with this technology. Conclusion: These findings suggest that plasma rich in growth factors is capable of promoting regeneration of gingival connective tissue by stimulating some of the main processes involved in wound regeneration.     

Instructions for Authors by China Journal of Oral and Maxillofacial Surgery

China Journal of Oral and Maxillofacial Surgery (CJOMS)(ISSN 1672-3244), founded in November 8 2002, is an official journal of Chinese Society of Oral and Maxillofacial Surgery, being designed to present the latest basic scientific and clinical findings of Oral and Maxillofacial Surgery in China. It is published quarterly currently by Editorial Board of China Journal of Oral and Maxillofacial Surgery.     

Instructions for Authors by China Journal of Oral and Maxillofacial Surgery x

China Journal of Oral and Maxillofacial Surgery （CJOMS）（ISSN 1672-3244）, founded in November 8 2002, is an official journal of Chinese Society of Oral and Maxillofacial Surgery, being designed to present the latest basic scientific and clinical findings of Oral and Maxillofacial Surgery in China. It is published quarterly currently by Editorial Board of China Journal of Oral and Maxillofacial Surgery.     

Regulation of Branching Morphogenesis in Fetal Mouse Submandibular Gland by Signaling Pathways Activated by Growth Factors and α6 Integrin

The submandibular gland (SMG) of the fetal mouse is useful for understanding the epithelial-mesenchymal interactions required for branching morphogenesis (BrM), which entails cleft formation and stalk elongation. We found that specific signaling pathways activated by growth factors or integrins regulate the processes of cleft formation and stalk elongation. Western blot analysis showed that epidermal growth factor (EGF) strongly stimulated the phosphorylation of extracellular signal-regulated kinase-1/2 (ERK-1/2) and weakly stimulated the phosphorylation of phospholipase Cγ1 (PLCγ1) and phosphatidylinositol-3 kinase (PI3K) in cultured E14 SMG. Meanwhile, fibroblast growth factor (FGF) 7 and FGF10 stimulated the phosphorylation of both PLCγ1 and PI3K, but elicited only minimal phosphorylation of ERK-1/2. Morphological studies revealed that EGF induced cleft formation of epithelial endpieces of mesenchyme-free SMG and that FGF7 stimulated both cleft formation and stalk elongation, whereas FGF10 induced only stalk elongation. U0126 (a MEK inhibitor) completely blocked cleft formation, while U73122 (a PLCγ1 inhibitor) suppressed stalk elongation. These results suggest that EGF stimulates cleft formation by activation of ERK1/2 and that FGF7 stimulates both cleft formation and stalk elongation by activation of PLCγ1 and partial activation of ERK1/2, and that FGF10 stimulates stalk elongation mainly by activation of PLCγ1. GoH3, a neutralizing antibody against the α6 integrin subunit, caused a slight increase over basal levels of ERK1/2 phosphorylation in cultured E14 SMG, but it had no discernible effect on EGF-induced phosphorylation. Based on these new findings regarding the effects of α6 integrin on growth factor receptor signals, we discuss the regulation of salivary gland development.     

Perception by the public and medical profession of oral and maxillofacial surgery--has it changed after 10 years?

Departments of oral and maxillofacial surgery (OMFS) aim to deliver an efficient and effective service. Clear understanding of what the speciality offers is central to appropriate referrals. Studies published 10 years ago showed there was limited awareness of the specialty. We present the results of a simple questionnaire study and compare the results with those of a previous survey. There has been some improvement in the perception of the role of OMFS, but only 34/100 of the public had heard of OMFS and none expected OMFS to treat patients who were unhappy with their facial appearance.     

How reliable and accurate is the shade determination of premolars by spectrophotometry?

Clinical Oral Investigations - To evaluate the reliability and accuracy of spectrophotometric shade determination of premolars and to compare the results with those for incisors. Fifty-seven...     

Periodontal assessment by right- and left-handed examiners: is there a difference?

BACKGROUND: Multiple factors that influence the precision of periodontal probing measurements have been identified. These factors can be categorized as being dependent upon host-related, probe-related, or examiner-related variables. However, the potential influence of examiner handedness (right or left) on the measurement of periodontal probing depths (PDs) has not been addressed. The purpose of this study was to determine whether the measurements of PDs in the right and left quadrants are influenced by the handedness of the examiner. METHODS: Eight systemically healthy adult subjects with varying degrees of attachment loss and a minimum of 20 teeth were examined by five right-handed and five left-handed clinicians. The 10 clinicians were trained and calibrated for reproducible probe placement and angulation. PDs were measured using a conventional periodontal probe at six sites per tooth. Mean PD measurements were compared between right- and left-handed examiners using analysis of variance (ANOVA) with a random patient effect to correlate participant data and a random effect for the examiner. RESULTS: There was no statistical difference in the measurement of PDs between right- and left-handed examiners at various locations in the mouth (P>0.17 in all cases). Only three individual sites showed a statistically significantly different mean PD between right- and left-handed examiners (unadjusted P<0.05; differences at or near 0.5 mm). Overall, right-handed examiners tended to record slightly higher PD measurements than left-handed examiners, but this difference did not reach statistical significance. CONCLUSIONS: The handedness of the periodontal examiner does not appear to influence the recorded measurement of probing depths. This finding is relevant to those conducting clinical research involving assessment of periodontal status.     

Chemical analysis of in vivo–irradiated dentine of head and neck cancer patients by ATR-FTIR and Raman spectroscopy

Objectives

To evaluate the effect of in vivo radiotherapy on the chemical properties of human dentine by Fourier-transform infrared spectroscopy (FTIR) and Raman analysis.

Materials and methods

Chemical composition was evaluated comparing control and irradiated group (n = 8). Irradiated teeth were obtained from radiotherapy patients subjected to fractionated X-ray radiation of 1.8 Gy daily totaling 72 Gy. The teeth were sectioned according to the type of dentine (crown or root dentine), obtaining 3-mm dentine cervical slices. The analyzed parameters by FTIR and Raman spectroscopies were mineral/matrix ratio (M:M), carbonate/mineral ratio (C:M), amide I/amide III ratio, and amide I/CH₂ ratio. Raman also calculated the phosphate and carbonate crystallinity.

Results

FTIR revealed that M:M had a decrease in both factors (p = 0.008; p = 0.043, respectively) and root dentine showed a lower C:M in the irradiated group (p = 0.003). Raman revealed a higher phosphate crystallinity and a lower carbonate crystallinity in crown dentine of irradiated group (p = 0.021; p = 0.039). For amide I/amide III, the irradiated showed a lower ratio when compared to the control group (FTIR p = 0.002; Raman p = 0.017). For amide I/CH₂, the root dentine showed a higher ratio than the crown dentine in both methods (p < 0.001).

Conclusions

Radiotherapy altered the chemical composition of human dentine. The exchange of phosphate-carbonate ions in the hydroxyapatite and higher concentration of organic components was found after radiotherapy.

Clinical relevance

The increased risk of radiation-related caries in patients undergoing head and neck radiotherapy is due not only to salivary, dietary, and microbiological changes but also to changes in tooth chemical composition.

     

Stress-related suicide by dentists and other health care workers: Fact or folklore?

BACKGROUND: The media repeatedly portrays dentists and other health professionals as being at risk of committing suicide. While this message often is accepted without question, there are little reliable data available that verifies this alleged risk. The relationship between professional stress and suicide, if any, has not been substantiated or quantified. TYPES OF STUDIES REVIEWED: The author evaluated the contemporary literature on stress and suicide in health professionals in an effort to verify or refute the widely held belief that dentists and other health care professionals are at higher risk of committing stress-related suicide. The author also surveyed dental schools to determine what efforts were being made to provide students with stress-management skills. RESULTS: The author found that there is little valid evidence that dentists are more prone to suicide than the general population, although some related data suggest that female dentists may be more vulnerable. Large-scale studies are needed before firmer conclusions can be reached. The author's survey shows that dental students generally receive some education on stress management, but many dental hygiene and graduate students do not. The author makes several recommendations for future research. CLINICAL IMPLICATIONS: Although some dentists leave the profession by way of suicide or career change at a time when their careers should be the most rewarding, available data on stress and its impact on suicide incidence are inconclusive and flawed. The profession needs to identify the causes of stress-related suicides and provide assistance to those people who are affected by stress.     

Statins regulate interleukin-1β-induced RANKL and osteoprotegerin production by human gingival fibroblasts

Stein SH, Dean IN, Rawal SY, Tipton DA. Statins regulate interleukin‐1β ‐ induced RANKL and osteoprotegerin production by human gingival fibroblasts. J Periodont Res 2011; 46: 483–490. © 2011 John Wiley & Sons A/S Background and Objective: Three‐hydroxy‐3‐methyl‐glutaryl‐CoA (HMG‐CoA) reductase competitive inhibitors, or ‘statins’, are widely used for lowering cholesterol and thereby reducing the risk of a heart attack. Recent data suggest that statins influence metabolic bone activity by their actions on three molecules: RANKL; RANK; and osteoprotegerin (OPG), the soluble decoy receptor for RANKL. The purpose of this study was to evaluate OPG and RANKL production in resting and interleukin‐1β (IL‐1β)‐activated human gingival fibroblasts (HGFs), and to determine the effect of statins on their production. Material and Methods: Fibroblasts were pre‐incubated with atorvastatin or simvastatin for 24 h in serum‐free medium, and then incubated with IL‐1β for 6 d. The concentration of OPG or RANKL in culture supernatants was measured by specific ELISA. Data were analyzed using analysis of variance and Scheffe’s F procedure for post hoc comparison. Results: IL‐1β (1 × 10^?8 m ) stimulated a significant increase in the production of OPG on days 1, 3 and 6. There was a trend towards an increase in RANKL production as a result of stimulation with IL‐1β. Both statins, at multiple concentrations, significantly increased the constitutive RANKL/OPG ratio. Only atorvastatin at the highest concentration (5 × 10^?6 m ) significantly increased the IL‐1β‐stimulated RANKL/OPG ratio. Conclusion: IL‐1β significantly increased OPG production by HGFs. The statins differed minimally in their effects on OPG and RANKL production by resting and IL‐1β‐activated HGFs. Both statins increased constitutive RANKL/OPG ratios, but generally not IL‐1β‐stimulated ratios. Thus, statins may influence the production of RANKL and OPG by HGFs to favor bone catabolism, under noninflammatory conditions.