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Expression of Wnt5a in Tooth Germs and the Related Signal Transduction Analysis

Archives of Oral Biology — 1/26/2010

Objective

Wnt5a is generally considered a non-canonical Wnt family member and plays an important role in the development of several tissues through regulation of cell fate, proliferation, migration, polarity and death. This study investigates its expression mode in human tooth development and the involved cell signal transduction pathways, as they remain unclear.

Design

The expression of Wnt5a was analyzed by immunohistochemistry method. Recombinant adenovirus encoding full-length Wnt5a cDNA was constructed to investigate four cell signal pathways and nine dentinogenesis nuclear transcription factors in response to Wnt5a in human dental papilla cells (HDPCs).

Results

Immunostaining revealed that Wnt5a was expressed in enamel epithelium cells from the bud stage, and in odontoblast layers and dental papilla tissues from early bell stage of human tooth development onward. Western blot analysis indicated that p42/44 MAPK, p38 MAPK, JNK and AKT signal pathways could be phosphorylated by WNT5A. RT-PCR analysis showed that Wnt5a increased the expression of DLX1, DLX2, LEF1, MSX2, PAX9 and RUNX2 mRNA, but decreased BARX1 and PITX2 mRNA.

Conclusions

It was concluded that WNT5A is expressed in human tooth development, and that p42/44 MAPK, p38 MAPK, JNK and AKT signal pathways and DLX1, DLX2, LEF1, MSX2, PAX9, RUNX2 could be activated by Wnt5a.

Hyposalivation, Xerostomia and Oral Health Status of HIV-infected Subjects in Thailand before HAART Era

Journal of Oral Pathology & Medicine — 1/5/2010

Background: The aims of this study were to determine hyposalivation, xerostomia, and oral health status of HIV-subjects in Thailand before highly active antiretroviral therapy era.

Methods: Oral examination and measurement of saliva flow rate of both unstimulated and wax-stimulated whole saliva were performed in 135 subjects (56 HIV-subjects, mean age: 34.5 years, and 79 non-HIV controls, mean age: 29.5 years). Presence of oral candidiasis, cervical root caries, and number of existing teeth were recorded. Microbiological investigation of oral Candida was conducted using oral rinse technique. Risk factors associated with hyposalivation and xerostomia were analysed.

Results: The unstimulated flow rates in HIV-subjects and non-HIV controls were 0.19 and 0.33 ml/min (P = 0.0024). For stimulated flow rates, the corresponding figures were 1.45 and 1.62 ml/min (P = 0.31). The unstimulated flow rate was significantly higher in the asymptomatic HIV-subjects: 0.17 ml/min, when compared with the symptomatic/AIDS group 0.11 ml/min (P = 0.003). No significant difference between the groups could be found with respect to stimulated flow rate. Hyposalivation was significantly associated with the colony forming unit of Candida. Smoking and alcohol consumption were significantly associated with hyposalivation, but not xerostomia. The following factors were significantly associated with both hyposalivation and xerostomia; sex, stage of HIV infection, risk group of HIV infection, systemic disease, and medication use.

Conclusions: Salivary flow rate of HIV-subjects in Thailand was affected by HIV infection. The rate was significantly decreased with advanced stage of the disease. Various factors including medication use were associated with hyposalivation and xerostomia among the subjects.

Efficacy of Enzymatic Mouth Rinses for Immobilisation of Protective Enzymes in the in situ Pellicle

Archives of Oral Biology — 12/28/2009

Aim

Mouth rinses containing enzymes are designed for patients suffering from xerostomia. The objective of the present in situ study was to investigate the efficacy of these rinses for targeted accumulation and immobilisation of protective enzymes in the acquired pellicle.

Methods

A number of six healthy subjects carried bovine enamel slabs fixed on individual upper jaw splints for pellicle formation in situ. After 1min, they rinsed with biot�ne or BioXtra for 10min, respectively. Enzyme activities of lysozyme, peroxidase and glucoseoxidase in the in situ pellicle and in the saliva were assayed before as well as 0, 20 and 40min after the rinses. The assays for the respective enzyme activities were based on fluorogenic substrates. Separate experiments were performed for the different enzymes and mouth rinses, respectively. Statistical evaluation was carried out with the Kruskal�Wallis test.

Results

None of the investigated rinses had any significant impact on the activities of lysozyme, peroxidase and glucoseoxidase detectable in the in situ pellicle or in the saliva (Kruskal�Wallis test, p>0.05). Despite the fact that both products should contain lactoperoxidase activity according to manufacturers� instructions, no peroxidase activity was measurable in the pure mouth rinses.

Conclusion

With the tested enzymatic mouth rinses targeted accumulation and immobilisation of protective enzymes in the in situ pellicle did not seem possible.

The Relationship between Sense of Coherence and Toothbrushing Behaviours in Iranian Adolescents in Mashhad

Journal of Clinical Periodontology — 12/15/2009

Aim: The aim of this study was to assess the association between Sense of Coherence (SOC) and toothbrushing behaviours in Iranian adolescents in Mashhad.

Materials and Methods: A representative stratified random sample of 1054 grade 6 Iranian students, living in Mashhad, answered a 37-item questionnaire with questions on socio-demographic characteristics, frequency of toothbrushing behaviours and Antonovsky's 13-item SOC scale. Binary logistic regression was used to test the association between SOC and toothbrushing behaviours.

Results: Higher SOC scores were significantly associated with more frequent toothbrushing behaviours (p=0.01). This positive association remained significant after adjusting for sex and father's education level (p=0.01). When testing this association for the boys and girls separately, the association was significant only for girls (p=0.02). However, the interaction between sex and SOC was not significant (p=0.56). The association between toothbrushing and sex remained significant after adjusting for SOC (p<0.001). Boys had a significantly stronger SOC than girls (p=0.04).

Conclusions: SOC was associated with toothbrushing frequency in Iranian adolescents in Mashhad. SOC did not fully explain the sex difference in toothbrushing behaviours.

Microwave Disinfection of Complete Dentures Contaminated In Vitro with Selected Bacteria

Journal of Prosthodontics — 11/26/2009

Purpose: This study evaluated the effectiveness of microwave irradiation for disinfection of simulated complete dentures.

Materials and Methods: Seventy dentures were fabricated in a standardized procedure, subjected to ethylene oxide sterilization, individually inoculated (10⁷ cfu/mL) with Staphylococcus aureus (n = 20), Pseudomona aeruginosa (n = 20), and Bacillus subtilis (n = 30) and incubated for 24 hours at 37�C. After that, 40 dentures were selected for microwaving. For each microorganism, 10 dentures were submitted to microwave irradiation at 650 W for 3 minutes. In addition, 10 dentures contaminated with B. subtilis were irradiated for 5 minutes. Thirty non-microwaved dentures (n = 10 for each bacteria) were used as positive controls. Replicate aliquots (25 μL) of suspensions were plated at dilutions of 10⁻³ to 10⁻⁶ on plates of selective media appropriate for each organism. After incubation (37�C for 48 hours), colonies were counted (cfu/mL). TSB beakers with the microwaved dentures were incubated at 37�C for a further 7 days to verify long-term disinfection. The data were statistically analyzed by the Kruskal-Wallis test (α= 0.05).

Results: No evidence of growth was observed at 48 hours for S. aureus and P. aeruginosa on plates, and no turbidity was visible in the TSB beakers of these specimens after 7 days of incubation. Dentures contaminated with B. subtilis and irradiated for 3 minutes produced microbial growth on six plates and turbidity on all TSB beakers. Microwaving for 5 minutes resulted in survival of B. subtilis in two plates and two beakers.

Conclusion: Microwave irradiation for 3 minutes at 650 W produced sterilization of complete dentures contaminated with S. aureus and P. aeruginosa. Dentures contaminated with B. subtilis were disinfected by microwave irradiation after 3 and 5 minutes at 650 W.