Fluoride varnish containing chitosan demonstrated sustained fluoride release.

Fluoride varnish is a professionally applied product that prevents dental caries. However, fluoride varnishes do not provide sustained fluoride release. The objective of this study was to prepare fluoride varnish formulations containing various amounts of chitosan that would generate sustained fluoride release. We evaluated their chemical structure, viscosity, and in vitro fluoride release. Furthermore, the 3-(4, 5-dimethylthiazolyl-2)-2,5diphenyltetrazolium bromide (MTT) assay and direct contact test were used to determine varnish cytotoxicity. We found that all fluoride varnish formulations had the same chemical structure. Their viscosity demonstrated a chitosan concentration-dependent increase. In vitro fluoride release showed a sustained fluoride release. The chitosan fluoride varnishes were cytotoxic to human gingival fibroblasts. We propose the new fluoride varnish formulation as a potential material to be used as a sustained release fluoride varnish.

Effect of Different Neutralizing Agents on Feldspathic Porcelain Etched by Hydrofluoric Acid.

OBJECTIVE: The aim of this study was to evaluate the effect of neutralizing agents on the shear bond strength of hydrofluoric (HF)-etched porcelain in nonaging and aging conditions. SUBJECTS AND METHODS: One hundred and twenty feldspathic porcelain specimens were prepared and divided into six groups to undergo different surface conditioning methods-group 1: control; group 2: HF; group 3: HF + calcium hydroxide; group 4: HF + calcium carbonate; group 5: HF + calcium gluconate; and group 6: HF + ultrasonic. All samples were immersed in 37°C distilled water for 24 h. Half of the samples were thermocycled in water for 5,000 cycles. The shear bond strength test was performed using a universal testing machine at a crosshead speed of 0.5 mm/min. Data were statistically analyzed by two-way ANOVA and Tukey's multiple comparison test at a 95% confidence level. The surface micromorphology and surface elements were analyzed using scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX), respectively. RESULTS: The shear bond strengths of groups 2-6 were significantly higher than the control group in both aging and nonaging conditions (p < 0.05). There were no significant differences among all of the HF-etched porcelain groups (p > 0.05). SEM images of groups 2-6 illustrated similar patterns of irregularity on the specimen surfaces. Elemental analysis of EDX demonstrated identical elements on surfaces of specimens of groups 2-6. CONCLUSION: Within the limitations of this study, shear bond strength values between HF-etched porcelain, HF-etching followed by application of neutralizing agents, and HF-etching followed by ultrasonic cleaning were not significantly different in both nonaging and aging conditions.

The synthesis and characterization of a novel potassium chloride-fluoridated hydroxyapatite varnish for treating dentin hypersensitivity.

Dentin hypersensitivity is treated using materials that occlude the dentinal tubules or release potassium ions that induce nerve desensitization. In this study we formulated a novel varnish containing potassium chloride and fluoridated hydroxyapatite and evaluated its physical properties and cytotoxicity. Potassium ion release from the varnish was measured. Dentin permeability was evaluated by measuring the hydraulic conductance of etched dentin discs treated with the varnish. The direct contact test and MTT assay were performed to evaluate the varnish's cytotoxicity. We found that the varnish released potassium ions over 6 h, and demonstrated a statistically higher reduction in dentin permeability compared to commercial fluoride varnish or control. Dentin disc scanning electron microscopy images demonstrated occluded dentinal tubules in the novel varnish group after brushing. The cytotoxicity tests indicated the varnish was biocompatible with gingival and pulpal fibroblasts. We propose the novel varnish is a potential material for use in hypersensitivity management.

Evaluation of biomimetic scaffold of gelatin-hydroxyapatite crosslink as a novel scaffold for tissue engineering: biocompatibility evaluation with human PDL fibroblasts, human mesenchymal stromal cells, and primary bone cells.

Biomimetic gelatin (gel)-hydroxyapatite (HA) composites have been prepared for studying hard tissue engineering scaffolds. However, the biocompatibility test of this form of material using these three cell types, which are periodontal ligament (PDL) fibroblast cells, human mesenchymal stromal cells (HMSc) and primary cells from human hip bone (HBc) has never been evaluated. The objective of this article is to prepare and evaluate the biocompatibility of gel-HA crosslinked scaffold for tissue engineering. Two different scaffolds were prepared: preparation (1), 2.5% gel/2.5% HA; preparation (2), 2.5% gel/5% HA. Three cell types including PDL, HMSc, and HBc were used. Assessment of biocompatibility and osteoblastic cellular responses was evaluated using a three-dimensional cell culture method and scanning electron microscopy (SEM). From SEM, it was observed that scaffold (1) exhibits stable porous formation with well-blended and dispersed HA powder. All three cell types were able to proliferate in both scaffolds. The HMSc and HBc got attached to the scaffolds to a significantly higher degree and subsequently proliferated more than PDL. The alkaline phosphatase (ALP) activities of HMSc and HBc were stronger when cultured in scaffold (S1) than (S2). It was seen that the two scaffold preparations show good biocompatibility with all three cell types tested. The better cellular responses with scaffold (S1) than (S2) might be due to the different structural and morphological characteristics, that is, scaffold (S1) retained more small-sized apatite crystals and a better developed pore configuration than scaffold (S2). Based on these findings, the biomimetically synthesized composite scaffolds have the potential to be used in hard tissue regeneration and tissue engineering fields.

Esthetic alveolar ridge preservation with calcium phosphate and collagen membrane: preliminary report.

OBJECTIVE: The objective of this study was to evaluate clinically, histologically and radiographically a ridge preservation technique used on extraction sockets grafted with biphasic calcium phosphate (BCP) and a resorbable collagen membrane. MATERIAL AND METHODS: Patients having a labial socket wall defect more than one-third in mesio-distal socket width after maxillary central incisor tooth extraction were included. The labial defect was sealed with resorbable collagen membrane and the defect filled with BCP. The grafted socket was covered with a resorbable collagen wound dressing material. The treated sockets were evaluated after a 4-month healing period when implants were placed and followed for up to 12 months. RESULTS: There were 8 subjects enrolled in this study. A statistical difference was found only in ridge width reduction at 3 mm below the cement-enamel junction of the adjacent teeth (P < .05) with 1 mm widening at 8 mm. The amount of new bone formation was extensively varied with diminutive graft remnants. Most cells in the connective tissue were osteopontin positive indicating they were osteoblast-like cells. A declination in the radiodensity of the grafted socket was observed during the analyzed period. CONCLUSION: Ridge preservation with BCP with collagen membrane can be used as an alternative treatment for maintaining ridge dimension before implant placement.

Oral squamous cell carcinoma: a clinicopathological study of 342 Thai cases.

AIM: To conduct a clinicopathological review of oral squamous cell carcinoma (SCC) and to analyze it with respect to gender, age at diagnosis, clinical presentation, lesion location, and histological grading. METHODS AND MATERIALS: Information on the clinicopathological characteristics of SCC was obtained from pathology reports of 342 cases. RESULTS: The male to female ratio was 1:1 and the incidence increased with age. Among the patients 4.7% were younger than 40 years and males were predominant in this subgroup. The alveolar ridge and gingiva were the most commonly affected sites (50%). The majority of the SCC cases presented as ulcers or masses. Swelling and/or pain were the first signs and/or symptoms in most patients (52.6%). The age at diagnosis in relation to the site of occurrence varied. Conventional SCC was the most common subtype (88%). Well-differentiated SCC was the most common histological grading (78.6%). CONCLUSION: In the present study, the incidence of SCC was age-related and showed equal gender distribution. CLINICAL SIGNIFICANCE: Routine examination of the oral cavity by dental practitioners and other health care providers aids in the early detection of premalignant and malignant oral disease. Dentists can play a significant role in disseminating information regarding oral cancer.

Expression of pro-inflammatory protein, iNOS, VEGF and COX-2 in Oral Squamous Cell Carcinoma (OSCC), relationship with angiogenesis and their clinico-pathological correlation

One main etiology for oral squamous cell carcinoma (OSCC) is inflammation. Inducible nitric oxide synthase (iNOS), vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) are the important molecules showing close relation to not only inflammation but also carcinogenesis and angiogenesis. Angiogenesis is defined as the formation of new blood vessels from existing vasculature. It is necessary for tumor growth and progression and also involved in metastasis. The objective of this research was to study the expression and relationship among iNOS, VEGF, COX-2, angiogenesis and their clinico-pathological correlation in OSCC. In this study, standard indirect immunohistochemical technique using polyclonal antibodies specific to human iNOS, VEGF, COX-2 and CD31 was performed in formalin-fixed paraffin-embedded tissue sections of 66 OSCC samples. The staining patterns and intensity are measured and analyzed statistically. The results showed that epithelial components of squamous cell carcinomas demonstrated moderate to intense staining for iNOS, VEGF and COX-2. iNOS shows correlation with cervical lymph node metastasis and tumor staging (TNM) of the patients and angiogenesis. VEGF shows correlation with tumor grading, tumor staging and angiogenesis. COX-2 shows correlation with cervical lymph node metastasis. In conclusion, the expression of iNOS, VEGF and COX-2 exists in OSCC. The data provided show the expression of these chemical mediators associated with carcinogenesis and angiogenesis in OSCC. It can be the primary database before using angiogenesis drug against these mediators for OSCC treatment (AU)

Expression of pro-inflammatory protein, iNOS, VEGF and COX-2 in oral squamous cell carcinoma (OSCC), relationship with angiogenesis and their clinico-pathological correlation.

One main etiology for oral squamous cell carcinoma (OSCC) is inflammation. Inducible nitric oxide synthase (iNOS), vascular endothelial growth factor (VEGF) and cyclooxygenase-2 (COX-2) are the important molecules showing close relation to not only inflammation but also carcinogenesis and angiogenesis. Angiogenesis is defined as the formation of new blood vessels from existing vasculature. It is necessary for tumor growth and progression and also involved in metastasis. The objective of this research was to study the expression and relationship among iNOS, VEGF, COX-2, angiogenesis and their clinico-pathological correlation in OSCC. In this study, standard indirect immunohistochemical technique using polyclonal antibodies specific to human iNOS, VEGF, COX-2 and CD31 was performed in formalin-fixed paraffin-embedded tissue sections of 66 OSCC samples. The staining patterns and intensity are measured and analyzed statistically. The results showed that epithelial components of squamous cell carcinomas demonstrated moderate to intense staining for iNOS, VEGF and COX-2. iNOS shows correlation with cervical lymph node metastasis and tumor staging (TNM) of the patients and angiogenesis. VEGF shows correlation with tumor grading, tumor staging and angiogenesis. COX-2 shows correlation with cervical lymph node metastasis. In conclusion, the expression of iNOS, VEGF and COX-2 exists in OSCC. The data provided show the expression of these chemical mediators associated with carcinogenesis and angiogenesis in OSCC. It can be the primary database before using angiogenesis drug against these mediators for OSCC treatment.

The application of acetic acid in the detection of oral squamous cell carcinoma.

BACKGROUND: Oral cancer is the fourth most common cancer in males and the seventh most common cancer in females in Thailand. The survival rates and quality of life of oral cancer patients will significantly be improved if they receive treatment for lesions that are less advanced or premalignant. Early diagnosis is therefore of paramount importance. A number of techniques have been developed to supplement clinical examination for oral malignancy. One interesting screening method is the application of 3% to 5% acetic acid, which has been used for cervical cancer screening. OBJECTIVES: The primary objective of this study was to assess the sensitivity, specificity, and accuracy of using vinegar (5% acetic acid) for the examination of oral cancer. The secondary objective was to investigate the association between clinical examination using acetic acid and expression of the tumor marker, p53. METHODS: The study included 30 participants suspected of having oral squamous cell carcinoma. Five percent acetic acid was applied to the lesions, followed by incisional biopsy. The specimens were microscopically examined for pathological diagnosis and p53 immunohistochemical investigation. RESULTS: The sensitivity, specificity, and accuracy of using acetic acid for oral cancer examination were 83.33%, 84.21%, and 83.64%, respectively. There was a statistically significant association between clinical examination using acetic acid and expression of p53 protein (P = .000). CONCLUSIONS: The results of this study suggest that 5% acetic acid has high sensitivity, specificity, and accuracy in detecting oral squamous cell carcinoma and might be used as an adjunct for oral cancer examination.

Adenomatoid odontogenic tumors: an analysis of 67 cases in a Thai population.

OBJECTIVE: The aim of this study was to determine the biologic profile of the adenomatoid odontogenic tumor (AOT) in a Thai population. STUDY DESIGN: Sixty-seven cases of AOT registered from January 1974 to May 2006 were studied retrospectively. Age, sex, variants of AOT, site and extent of tumors, associated impacted teeth, initial clinical diagnoses, clinical presentations, and duration of symptoms were analyzed. RESULTS: All AOT cases were intraosseously located, of which 55.2% were follicular and 44.8% extrafollicular. The 2 variants together were found more frequently in the maxilla than in the mandible, with a ratio of 2:1. Females were affected more often than males, with a ratio of 1.8:1. The peak incidence (56.7%) was found in the second decade of life. The majority of AOT lesions (68.7%) was found in the anterior jaws. Adenomatoid odontogenic tumors were observed more often on the left side of jaws (50.7% vs. 38.8%). Canines were the most common teeth associated with follicular AOT (67.5%), and the maxillary canines alone accounted for 51.3% of all cases. The majority of our patients presented with a painless swelling and with duration of symptoms of 6 months and longer. CONCLUSIONS: The distribution and characteristics of AOT in a Thai population are similar to the findings found in other populations. Interestingly, in this series we observed a case involving an impacted deciduous canine and a case associated with an impacted maxillary third molar.

Osteopontin expression in normal skin and non-melanoma skin tumors.

Osteopontin (OPN) is an adhesive, matricellular glycoprotein, whose expression is elevated in many types of cancer and has been shown to facilitate tumorigenesis in vivo. To understand the role of OPN in human skin cancer, this study is designed to determine whether OPN is expressed in premalignant [solar/actinic keratosis (AK)] and in malignant skin lesions such as squamous cell carcinomas (SCC) and basal cell carcinomas (BCC), as well as in normal skin exposed or not exposed to sunlight. Immunohistochemical analyses showed that OPN is expressed in SCC (20/20 cases) and in AK (16/16 cases), which are precursors to SCC, but is absent or minimally expressed in solid BCC (17 cases). However, positive staining for OPN was observed in those BCC that manifest differentiation toward epidermal appendages such as keratotic BCC. In sunlight-exposed normal skin, OPN is minimally expressed in the basal cell layer, but in contrast to those not exposed to sunlight, OPN is more prominent in the spinous cell layer with increasing intensity toward the granular cell layer. Additionally, OPN is expressed in the hair follicles, sebaceous glands, and sweat glands of normal skin. In conclusion, these data suggest that OPN is associated with keratinocyte differentiation and that it is expressed in AK and SCC, which have metastatic potential, but minimally expressed in solid BCC.

An updated clinical and epidemiological profile of the adenomatoid odontogenic tumour: a collaborative retrospective study.

BACKGROUND: Adenomatoid odontogenic tumour (AOT) is a benign odontogenic jaw lesion. The aim of this study was to update the biological profile of AOT. MATERIAL AND METHODS: Cases published in the literature and cases in files of co-authors were included. RESULTS: 550 new cases were retrieved, and of a total of 1082 cases analysed, 87.2% were found in the second and third decades. The M:F ratio was 1:1.9. 70.8% were of the follicular variant (extrafollicular: 26.9%, peripheral: 2.3%). 64.3% occurred in the maxilla. 60% of follicular AOTs were associated with unerupted canines. Nineteen cases of AOT (2.8%, M:F ratio was 1:1.4) were associated with embedded third molars. Twenty-two peripheral AOTs (2.3%, M:F ratio was 1:5.3) were recorded. The relative frequency (RF) of AOT ranged between 0.6% and 38.5%, revealing a considerably wider AOT/RF range than hitherto reported (2.2-7.1%). CONCLUSIONS: This updated review based on the largest number of AOT cases ever presented, confirms the distinctive, although not pathognomonic clinicopathological profile of the AOT, its worldwide occurrence, and its consistently benign behaviour.

Fibroblast interaction with carboxymethylchitosan-based hydrogels.

The interaction between L929 cells and carboxymethylchitosan (CM-chitosan)-based hydrogels, hydrogels from pure CM-chitosan and its blends, was examined in this study. Cytotoxicity of all materials was also assessed. The cellular morphology and behavior on the surfaces of the hydrogels were observed by scanning electron microscopy (SEM). The effects of various parameters, e.g., type and content of blended polymers, surface structure of hydrogels, and steaming condition used for the preparation of the hydrogels, on the cell-material response were investigated. The results of the cytotoxicity test revealed that all hydrogels were non-cytotoxic. The SEM micrographs demonstrated that the cells proliferated and spread onto a porous CM-chitosan sample. Better cell spreading was found on a flat surface of a CM-chitosan film. Rounded cells were observed when poly(vinyl alcohol) (PVA) was incorporated into CM-chitosan. Fewer cells were found when the content of PVA increased. Spherical clusters of the aggregated cells existed in the blends with ultra high viscosity carboxymethylcellulose (CM-cellulose). In contrast, with the use of low viscosity CM-cellulose, the cells appeared more spreading. The attached cells on the CM-chitosan film steamed at the highest temperature and longest period appeared to spread the most among all tested steaming conditions.

Preparation of acrylic grafted chitin for wound dressing application.

Chitin grafted with poly(acrylic acid) (chitin-PAA) was prepared with the aim of obtaining a hydrogel characteristic for wound dressing application. The chitin-PAA films were synthesized at various acrylic acid feed contents to investigate its effect on water sorption ability. Acrylic acid (AA) was first linked to chitin, acting as the active grafting sites on the chain that was further polymerized to form a network structure. The evidences of grafting were found from FTIR and solid state 13C NMR spectra. The TGA results exhibited the high degradation temperature of the grafted product suggesting the formation of a network structure. The degree of swelling (DS) of chitin-PAA films was found in the range of 30-60 times of their original weights depending upon the monomer feed content. The chitin-PAA film with 1:4 weight ratio of chitin:AA, possessed optimal physical properties. The cytocompatibility of the film was investigated with a cell line of L929 mouse fibroblasts. The morphology and behavior of the cells on the chitin-PAA film were determined after different time periods of culture up to 14 days. The L929 cells proliferated and attached well onto the film. These results suggested that the 1:4 chitin-PAA has a potential to be used as a wound dressing.

Invasion of Porphyromonas gingivalis into human gingival fibroblasts in vitro.

Porphyromonas gingivalis, one of the important periodontal pathogens, exhibits many virulence properties. Among these, the adhesion to and invasion into host tissues are crucial for the initiation and progression of periodontal diseases. While evidence indicating the ability of this organism to adhere to and invade into epithelial cells as well as endothelial cells has accumulated, that involving the gingival fibroblasts is very limited. Therefore, this study aimed to determine the ability of P. gingivalis to invade primary cultures of human gingival fibroblasts using the antibiotic protection assay. In addition, interactions between P. gingivalis and the gingival fibroblasts were investigated using electron microscopy. The results demonstrated that P. gingivalis 381 could invade human gingival fibroblasts with an invasion efficiency of 0.17%. Using the scanning electron microscopic study, numerous filopodia were seen on the surfaces of gingival fibroblasts after P. gingivalis adhesion. The transmission electron microscopy revealed the presence of an intracellular bacterium. After 90 min incubation, the bacterium was found in the cytoplasm of the gingival fibroblasts, without membrane surrounding. Some fibroblasts contained a number of vacuoles and dilated rough endoplasmic reticulum even when bacteria were not found intracellularly. Thus, the invasion of this organism into the gingival fibroblasts may play a direct role in the destruction of the periodontal tissues and may also relate to the difficulties of eradicating the bacteria from periodontitis lesions.

Effects of autoclave sterilization on properties of dental rubber dam as related to its use as barrier membrane in guided tissue regeneration.

BACKGROUND AND OBJECTIVE: Dental rubber dams (RDs) were used as barrier membranes in guided tissue regeneration for the treatment of periodontal intraosseous defects with acceptable clinical results. The aim of the present study was to investigate the effects of autoclave sterilization on properties of RD as related to its use as a barrier membrane in guided tissue regeneration. METHODS: RDs were sterilized by either an autoclave, gamma irradiation, or chemical agents and then co-cultured with human gingival fibroblasts. The cell responses to sterilized RDs were investigated by inverted phase contrast microscopy, scanning electron microscopy (SEM) and 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) technique. The surface alterations of the autoclaved RDs were observed under SEM. The tensile strength, tear strength and elongation at break of the autoclaved RDs were tested by a universal testing machine. RESULTS: The results from cell culture, microscopic and MTT studies showed that RDs sterilized by autoclave and gamma irradiation did not deteriorate gingival fibroblasts and provided surfaces suitable for cell attachment, whereas chemical-sterilized RDs were toxic to these cells. Ultrastructurally, surface changes from the non-autoclaved RDs, including some melted areas, small pores and folds were observed on the autoclaved RD surface. The tensile strength and tear strength of the autoclaved RDs were significantly lower than those of the non-autoclaved RDs (p = 0.042, p < 0.001, respectively). In contrast, the elongation at break of the autoclaved RDs was higher than that of the non-autoclaved RDs (p < 0.001). CONCLUSION: These results suggest that the autoclave sterilization deteriorated the physical properties of RDs even though they seemed to be compatible to the cultured human cells. Therefore, the sterilization method should be taken into consideration when RDs are utilized as barrier membranes.

Connective tissue and bacterial deposits on rubber dam sheet and ePTFE barrier membranes in guided periodontal tissue regeneration.

The aim of this study was to compare the connective tissue and bacterial deposits on rubber dam sheets and expanded polytetrafluoroethylene membranes used as barrier membranes in guided tissue regeneration for periodontal treatment. Twenty patients having intrabony defects and/or furcation defects were surgically treated by guided tissue regeneration employing either rubber dam sheets (10 patients) or expanded polytetrafluoroethylene membranes (10 patients) as barrier membranes. Four to six weeks after the first operation, membranes were retrieved from the lesion sites and processed for scanning electron microscopy. The lesion-facing surfaces of membranes were examined for the presence of connective tissue and bacterial deposits. The differences between the numbers of fields and the distributions of connective tissue and bacteria on both types of membranes were analysed by the Chi-square test at the level of 0.05 significance. The results showed a lot of fibroblasts with their secreted extracellular matrices, known as components of the connective tissue on rubber dam sheets and expanded polytetrafluoroethylene membranes. There was no significant difference in the total number of connective tissue on both types of membranes (P = 0.456). Many bacterial forms including cocci, bacilli, filaments and spirochetes with the interbacterial matrices were identified. The total number of bacteria on rubber dam sheets was statistically less than that on expanded polytetrafluoroethylene membranes (P < 0.001). The comparable number of connective tissue on both types of membranes suggests that the healing process under both types of membranes was also comparable. Therefore, the rubber dam sheet might be used as a barrier membrane in guided tissue regeneration.

Effects of lead on the proliferation, protein production, and osteocalcin secretion of human dental pulp cells in vitro.

Teeth have been recognized as providing a useful long-term record of lead (Pb2+) uptake. However, information regarding the effects of lead on dental pulp tissue cells that foster dentinogenesis is scarce. This study investigated the effects of lead on dental pulp tissue using human dental pulp fibroblasts in vitro. Dental pulp cells from the teeth of young patients (aged 17-24 years) were cultured and subsequently treated with lead glutamate. It was shown that, in serum-free conditions, all the tested concentrations of lead (4.5 x 10(-5) M, 4.5 x 10(-6) M, and 4.5 x 10(-7) M) significantly increased pulpal cell proliferation. In the presence of 2% fetal bovine serum, increasing cell proliferation was observed only after exposure to a lead concentration of 4.5 x 10(-5) M. However, protein, procollagen type I, and osteocalcin productions were significantly decreased. The alteration of cell population and protein production of affected human dental pulp shown in this study are toxic effects of the lead.