Biocompatibility study of tobacco mosaic virus nanoparticles on human alveolar bone cells.

One of the most important factors in a dental implant's success is an adequate quantity of supporting bone. However, there are still some limitations for the bone substitution material. Previous studies found that tobacco mosaic virus (TMV) had the potential for bone formation induction. The aim of this study was to evaluate the biocompatibility of TMV with primary human alveolar bone cells. Primary human alveolar bone cells were cultured on TMV coated substrates. Cell viability, alkaline phosphatase activity, calcium matrix mineralization forming ability, immunofluorescence staining for osteocalcin synthesis and cell morphology were assessed. The results showed that primary human alveolar bone cells cultured on the TMV coated substrates had a higher metabolic rate than the non-TMV coated control group at days 1, 3, 7 and 14. Moreover, the calcium deposition was positive and the alkaline phosphatase activity assay was found significantly greater than the control group at day 14 (p < 0.05). The osteocalcin protein synthesis was found in both the TMV coated substrates and the control group. The immunofluorescence study revealed that in the TMV coated substrates group, the cell morphology changed into a polygonal shape and aggregated more quickly than the control group. The present findings conclude that TMV is biocompatible with primary human alveolar bone cells and also shows osteoinduction potential.

Effect of probiotic Lactobacillus paracasei on tumor necrosis factor-alpha level in gingival crevicular fluid of patients undergoing impacted third molar removal.

PURPOSE: This study was conducted to evaluate the effects of the probiotic Lactobacillus paracasei in patients undergoing removal of impacted mandibular third molars, focusing on tumor necrosis factor alpha (TNF-α) levels in gingival crevicular fluid, pain, swelling, trismus, and interincisal distance. METHODS: Thirty patients were divided into two groups: (1) wound irrigation with the probiotic, and (2) irrigation with 0.9% normal saline. The data were collected at the baseline, and at 24 h and 7 days after the operation. The TNF-α level in gingival crevicular fluid was determined using the ELISA technique. RESULTS: In the experimental group, the probiotic L. paracasei MSMC39 reduced the TNF-α level in gingival crevicular fluid to a significantly greater degree than in the control group (P < 0.05). Pain, swelling and trismus evaluated in terms of a visual analog scale (VAS) score were lower in the experimental group than in the control group, but not to a statistically significant degree (P > 0.05). The mean interincisal distance in the experimental group was higher than that in the control group (P = 0.014). CONCLUSION: The probiotic L. paracasei is able to reduce the level of TNF-α in gingival crevicular fluid and can ameliorate postoperative complications after mandibular molar removal.

Biocompatibility study of modified injectable hyaluronic acid hydrogel with mannitol/BSA to alveolar bone cells.

The quality and quantity of bone are crucial to the success of dental implant treatment. Recently, bone grafting materials have reached some limitations. This study aimed to evaluate the biocompatibility of novel drug delivery material, injectable methacrylated hyaluronic acid hydrogel incorporated with different ratios of mannitol and BSA (Man/BSA MeHA), to human alveolar bone cells. The three-dimensionally encapsulated cell culture was evaluated with the resazurin cell viability test, alkaline phosphatase activity assay, immunohistochemistry test for collagen type-I synthesis, and cell morphology. The results showed that the encapsulated cells were viable in all four ratios of Man/BSA MeHA hydrogel and the average metabolic rate was not less than the control group. The morphology test showed round shape cells at the upper portion of the hydrogel and fibroblast-like or polygonal shape at the lower portion of hydrogel next to the culture plate. All four groups could express enzyme alkaline phosphatase and collagen type-I. In conclusion, four ratios of Man/BSA MeHA hydrogel were biocompatible with primary human alveolar bone cells.

The expression of Cathepsin L in oral lichen planus.

BACKGROUND: Malignant transformation of oral lichen planus (OLP) was reported particularly in erosive type, however, it remains inconclusive. Cathepsin L was shown to promote tumor growth and invasion in many cancers. Therefore, cathepsin L expression in erosive and non-erosive OLP compared with oral epithelial dysplasia and oral squamous cell carcinoma (OSCC) were investigated. METHODS: Thirty specimens of OLP (15 cases each of erosive and non-erosive OLP), 10 cases of oral epithelial dysplasia and 10 cases of OSCC were included. Ten healthy gingiva specimens were served as controls. All specimens were stained with cathepsin L antibody using immunohistochemistry technique. RESULTS: Cathepsin L was expressed in all OLP and OSCC cases. In oral epithelial dysplasia and healthy gingiva, the expression was found at 90% and 50% respectively. The percentage of positive cells was the highest in erosive OLP (27.26 ± 12.09%), followed by non-erosive OLP (20.85 ± 7.43%), OSCC (20.15 ± 15.70%), oral epithelial dysplasia (9.24 ± 7.00%) and healthy gingiva (2.27 ± 5.65%). Most of non-erosive OLP cases showed mild staining intensity while erosive OLP and OSCC showed moderate staining intensity. Cathepsin L was mainly expressed at basement membrane zone and inflammatory cells of OLP. In OSCC, the expression was found in tumor islands and keratin pearls. In oral epithelial dysplasia and normal gingiva, cathepsin L expressions were low and presented in scattered pattern in both epithelium and connective tissue. CONCLUSION: According to the patterns of expression in this study, cathepsin L could be implicated in pathogenesis and severity of OLP.

Oral manifestations, salivary flow rates and Candida species in Thai HIV-infected patients.

BACKGROUND: Effects of various Highly Active Antiretroviral Therapy (HAART) regimens on oral heath are unclear. Objectives: We aimed to evaluate effects of HAART on oral manifestations, salivary flow rates (SFR) and Candida species in HIV-infected patients who took mostly non-protease inhibitor-based HAART regimens. MATERIAL AND METHODS: A cross-sectional study was performed on HIV-infected patients taking and never taken HAART who attended Thai Red Cross AIDS Research Centre (n = 48). Non-HIV subjects were recruited as control (n = 20). Oral conditions and salivary flow rates were evaluated using oral examination and measurement of unstimulated and stimulated saliva. In addition, Candida colonization counts (colony forming units; CFUs) and Candida species from the collected saliva were evaluated using CHROMagar. RESULTS: The most common oral manifestation in HIV-infected subjects taking HAART was hyperpigmentation. Unstimulated and stimulated SFR among the three groups were not statistically significant. Candida colonization was detected in 64%, 65% and 35% of HIV-infected subjects taking HAART, HAART-naïve, and non-HIV subjects, respectively. While 20% and 35% of HIV-infected subjects with and without HAART, respectively, had Candida CFUs higher than 500/ml, all non-HIV carriers had Candida CFUs lower than 500/ml. The most common Candida colonization species was C. albicans in HAART and non-HIV groups. Interestingly, HAART-naïve group was colonized more by non-albicans species. CONCLUSIONS: HAART has minimal effects on oral health. While HAART may not prevent Candida colonization, it might lead to reduction of non-albicans species. Because maintaining low Candida counts is important, HAART administration and antifungal sensitivity test should be considered in HIV-infected patients. Key words:HIV, Candida, HAART, Oral manifestation, Salivary flow rates.

Site-specific regulation of oral mucosa-recruiting CD8+ T cells in a mouse contact allergy model.

Contact allergy is a T cell-mediated, delayed-type hypersensitivity generated by contact exposure of an allergen to the skin and mucosal surface. The clinical manifestations of allergic responses between the skin and oral mucosa vary and the differences in immunopathology have not been clarified. We generated hapten-induced contact hypersensitivity (CH) of the buccal mucosa (BM) in parallel studies with ear skin (ES) CH, and observed several characteristic findings of BM CH. The BM challenge induced more rapid and more severe inflammation than the ES challenge, with abundant granulocyte and CD8+ T cell infiltration. However, these inflammatory responses diminished quickly. Recruiting CD8+ T cells in the BM had higher ratios of CD62L-CD44low-hi memory-type cells, and showed impaired IFN-γ, greater PD-1, and comparable Ki-67 expression, suggesting that the recruiting-proliferating CD8+ T cells were unable to differentiate into effector T cells and converted into exhausted T cells at the local site. This finding may explain the rapid recovery of the BM from severe inflammation. Preferentially greater expression of PD-1 ligand (B7-H1), was observed in the BM epithelium under the peak inflammation, and the absence of B7-H1 further accelerated CH responses, suggesting the occurrence of PD-1:B7-H1-mediated immune regulation at the local site. Our results may facilitate the understanding of the unique features of contact allergies in the oral mucosa, and guide the development of new strategies for control of contact allergy.

Higher prevalence of oral human papillomavirus infection in HIV-positive than HIV-negative Thai men and women.

OBJECTIVE: This study was designed to investigate the prevalence of oral human papillomavirus (HPV) infection among HIV-positive and HIV-negative Thai men and women. METHODS: Participants including men who have sex with men (MSM) and heterosexual women were enrolled at the Thai Red Cross Anonymous Clinic in Bangkok. History taking and oral examination were performed by three independent dentists after calibration. HPV infection was evaluated from oral rinse with mouthwash collected at the time of examination. HPV typing was performed by PCR and nucleic acid hybridization to detect thirty-seven HPV DNA genotypes using Linear Array(®) HPV Genotyping Test (Roche Molecular System, Inc.). RESULTS: 244 subjects were enrolled in the study, consisted of 187 HIV-positive (51.9% women and 48.1% MSM) and 57 HIV-negative (21.0% women and 79.0% MSM) Thai subjects. The prevalence of oral HPV infection was 17.2% in HIV-positive subjects whereas only 5.3% of HIV-negative cases had HPV detected in their oral rinses (p=0.0346). Among HIV positive subjects, MSM had higher chance of having HPV infection than females (25% vs. 9.4%, p=0.0074). CONCLUSIONS: HIV-positive Thai MSM and women had higher prevalence of oral HPV infection than those without HIV.

Thai dental practitioners' knowledge and attitudes regarding patients with HIV.

To investigate the knowledge and attitudes of Thai dental practitioners regarding patients with HIV, a cross-sectional study using self-administered questionnaires was conducted. The questionnaires requested demographic information and included questions evaluating the knowledge and attitude of dental practitioners towards HIV. The results were analyzed using Scheffe method for multiple comparisons at the 95 percent confidence level. Out of 1,200 questionnaires sent, 446 questionnaires were returned (response rate 37.2 percent). The subjects included final (sixth)-year dental students (11.9 percent), general dentists (29.1 percent), specialist dentists (15.5 percent), dental hygienists (30.5 percent), and dental assistants (13 percent). More than 80 percent of the dental practitioners correctly answered the questions testing their basic knowledge of HIV such as routes of transmission and common opportunistic infections. However, knowledge about HIV pathogenesis, complications, and advances in HIV management was lacking. Dental hygienists and dental assistants had statistically significant lower scores in knowledge about HIV than other groups. Sixty-seven percent of dental practitioners said they feel worried when treating patients with HIV, and 20.4 percent said they would deny treatment for patients with HIV if possible. While knowledge about HIV may be adequate among dental practitioners in Thailand, greater effort should be put into emphasizing positive attitudes towards patients with HIV.

Perceived dental needs and attitudes toward dental treatments in HIV-infected Thais.

Despite the advancement in highly active antiretroviral therapy and improved health status of HIV-infected individuals, dental problems are still affecting their life and well-beings. We aimed to establish the prevalence of oral and dental complaints among HIV-infected patients, the prevalence of delayed access to dental service, and factors related with delayed access to dental service. A cross-sectional study using self-report questionnaire completed by the HIV-positive subjects was conducted at the largest HIV research clinic in Thailand during 2009-2010. Of all 299 subjects (28.6% males, 71% females, and 0.4% sex change from male to female: ages ranged from 22 to 59 years [mean 36.7±5.53)]), 84.3% reported of having past or present illnesses or problems related to the dental or oral conditions. The most reported problems were dental hypersensitivity (93.3%), bleeding from the gum (92.1%), and having dental caries (65.9%). Two-hundred and forty-two subjects (80.9%) would not disclose their HIV status when seeing a dentist. The most cited reasons of such behavior were their personal right whether to reveal or not, and being afraid of not receiving dental treatment from the dentists or staffs (51.7 and 40.9%, respectively). It is important to note that HIV-subjects admitted to having fear of being discriminated by the dental staffs even if they trusted their dentists as having high morality. In conclusion, our HIV-subjects had good basic knowledge of oral health with regard to HIV infection, experienced common dental problems, and wished to have accesses to HIV-dental specialist services, if possible.

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.