Adenoviral-mediated gene transfer into bone marrow: an effective surgical technique in rat.

BACKGROUND: The role of transforming growth factor-beta 1 (TGF-ß1) in the onset of bone marrow fibrosis has been confirmed in some animal models. To further understand the genetic expression of some myeloproliferative disorders affecting marrow stem cells, however, it is necessary to develop a specific and reliable procedure to deliver modified adenoviral vectors into the bone marrow cavity. The aim of this paper is to report a surgical technique designed to deliver an adenoviral vector-mediated gene expressing TGF-ß1 into the bone marrow of rat femurs. METHODS: Forty-two Sprague-Dawley rats were used in the study. Rat femurs were exposed and the compact and trabecular bones at the proximal head removed. An intrabone marrow injection of a mutated TGF-ß1 adenoviral vector, a null adenoviral vector, or PBS was delivered into the bone. Three groups were accounted (n = 14 per group): fibrogenic and positive and negative controls. The quality of the surgical entrance was assessed by means of computerized tomography and histological changes were assessed by histochemistry. The concentration of TGF-ß1 in the bone marrow was determined by ELISA. RESULTS: The surgical technique was conducted under ideal timing (approx. 10 min) and no surgical or postsurgical complications were observed. Computerized tomography revealed no changes in the bone tissue and a clean entrance was delimited through the bone to the bone marrow. HE and Masson's trichrome staining indicated highly fibrotic areas in the profibrotic group and bone marrow lavage reported a significantly higher concentration of TGF-ß1 (p < 0.05) in that same group. CONCLUSIONS: The present study confirmed that the proposed surgical technique is an effective method to deliver adenoviral vectors into the femoral bone marrow to investigate the physiopathology of bone marrow fibrosis in rats.

Prostaglandin E2 affects osteoblast biology in a dose-dependent manner: an in vitro study.

OBJECTIVE: This study aimed to determine in vitro how exogenous PGE(2) affects the expression of genes in cultured osteoblasts by relative quantitation PCR. DESIGN: Cultured osteoblasts were exposed to 10(-3)M, 10(-5)M or 10(-7)M PGE(2) over 5, 10, 15 and 20 days. RESULTS: RANKL expression was higher after 5 days of exposure (p<0.05), but thereafter reduced in those treated with the two lower doses of PGE(2) (p<0.01). RANKL/OPG ratio reported in favour of OPG gene expression and alkaline phosphatase gene expression increased in osteoblasts exposed to the two lower doses of the eicosanoid after 15 days. Conversely, prostaglandin E synthase, a cytokine produced during PGE(2) synthesis, gene expression was significantly reduced at 15 and 20 days (p<0.01 and 0.05 respectively). The results from this study add to the current knowledge of the mechanisms by which PGE(2) modulates the osteoblast biology in a dose-dependent manner. CONCLUSIONS: It is proposed that PGE(2)at a low dose switch osteoblast's biology in favour of bone apposition by: first, inducing a significantly higher OPG gene expression overwhelming RANKL gene expression; second, reducing PGEs synthesis; and third, increasing ALP gene expression. An opposite effect is expected when the concentration of the eicosanoid overpass certain levels.

ER: YAG laser for composite removal after bracket debonding: a qualitative SEM analysis.

OBJECTIVE: To qualitatively compare the effectiveness of the Er:YAG laser with conventional methods for removing the composite remnants and the enamel ablation produced after bracket debonding. MATERIALS AND METHODS: Brackets were bonded on 12 extracted premolars and the composite remnants were removed by 3 different methods: tungsten-carbide bur and 2 Er:YAG laser intervals. Four other premolars were used as a control group. Samples were analyzed with scanning electron microscopy (SEM) and the amount of composite remaining on the teeth and the amount of enamel ablated on each sample were qualitatively ranked by 3 examiners. The results were statistically analyzed by the Tukey test. RESULTS: The Er:YAG laser performed significantly better than the conventional technique for removing the composite remnants, but the amount of enamel ablation produced was significantly higher. CONCLUSIONS: The Er:YAG laser can be used to remove composite remnants after orthodontic bracket debonding, but further studies are required to determine the ideal specifications of this type of laser to reduce the amount of enamel ablation produced under the specifications used in this study.

Prevalence of malocclusions in a young Brazilian population.

Malocclusions are generally treated in adolescents and adults, but they are established at an early age. The purpose of this study was to determine the prevalence of malocclusions in a young Brazilian population. The sample included 926 children, 8 to 12 years old, attending 5 public schools in the state of Goias, Brazil The type of occlusion was visually determined during the oral exam and statistical analysis, Chi-square test, was performed to correlate the prevalence of malocclusion with gender and with age. 819 patients out of the 926 patients had some type of malocclusion. From those, 513 patients had a class I malocclusion, 201 patients were classified as class II malocclusion, and 105 patients were class III malocclusion. Vertically, 62 patients showed a deep bite and 61 patients had an open bite. Transversely, 40 patients presented a bilateral posterior crossbite, 54 patients had a posterior crossbite on the left side, and 39 patients had a posterior crossbite on the right side. No significant correlation between gender and malocclusions was found and the number of patients with malocclusions between boys and girls were similar. Considering the three spatial planes, there is a high prevalence of malocclusions among the young Brazilian population. Therefore, the dental community must improve health policies and treat malocclusions earlier.

Dimensional changes in dental arches after treatment with a prefabricated functional appliance.

The purpose of this study was to determine the effect of the T4K, a prefabricated functional appliance, on the transverse and anterior-height dimensions of the maxillary and mandibular dental arches. Dimensions before and after treatment were measured on the sample, then, natural growth was subtracted from the treatment effects and compared with twice the error of the method. A clinically significant increase of both dimensions was observed in the maxilla and mandible when Class II malocclusion patients were treated with the T4K. Therefore, this retrospective study demonstrates that T4K is a valid treatment choice at an early age when transverse expansion is part of the treatment goal.

Prostaglandin E2 enhances transforming growth factor-beta 1 and TGF-beta receptors synthesis: an in vivo and in vitro study.

The aims of this study were to determine how Prostaglandin E2 (PGE2) locally applied affected the immunodistribution of latent transforming growth factor-beta 1 (TGF-beta1), and how the eicosanoid modified TGF-beta1 release and TGF-beta receptors gene expression in cultured osteoblasts. PGE2 locally delivered on the rat mandible at doses of 0.1 and 0.05 mg/day, but not 0.025 mg/day, over 20 days significantly increased latent TGF-beta1 immunodistribution (P<0.001), comparing with a placebo-treated group. Cultured osteoblasts stimulated with 10(-5) or 10(-7)M PGE2 significantly varied the level of activated TGF-beta1 released into supernatants at different experimental periods compared with negative and positive controls. TGF-beta receptor type I gene expression was significantly increased in osteoblasts (P<0.01) after 10 days of treatment with 10(-5) and 10(-7)M PGE2, whereas 10(-3) M PGE2 produced the opposite effect. It is concluded that PGE2 may stimulate bone deposition by affecting TGF-beta pathway. This effect on the pathway appears to be dose-dependent.

Local application of prostaglandin E2 reduces trap, calcitonin receptor and metalloproteinase-2 immunoreactivity in the rat periodontium.

It has been shown that prostaglandin E2 (PGE2) locally released adjacent to the mandible over a 20-day period increases alveolar bone area, in part, due to a reduction in the percentage of eroded surface. To determine the effect of PGE2 on alveolar bone resorption, left mandibles from 24 Lewis rats were treated over a 20-day period with a local application of PGE2 (0.1, 0.05 or 0.025 mg/day) or placebo. The right side served as the non-treated matched control. Tissue sections were stained for tartrate resistant acid phosphatase (TRAP) calcitonin receptor (CTR) and metalloproteinase-2 (MMP-2). Matched samples were analysed by Wilcoxon matched pairs test and, a non-parametric one-way analysis of variance compared groups of treatment. Those tissues treated with PGE2 at doses of 0.1 and 0.05 mg/day showed significantly reduced numbers of TRAP and CTR-positive multinucleated cells compared with matched controls (p<0.005), as well as significantly reduced numbers of TRAP- and CTR-positive multinucleated cells when compared with the placebo-treated group (p<0.001). The number of periodontal ligament cells expressing MMP-2 was also significantly reduced in tissues treated with the two higher doses of PGE2 (p<0.001) comparing with both matched controls and the placebo-treated group. Following a 20-day period, locally released PGE2 at doses of 0.1 and 0.05 mg/day appears to affect alveolar bone resorption in the periodontium of rats, as the number of multinucleated cells expressing TRAP and CTR are significantly reduced. Furthermore, the same doses of PGE2 also significantly reduced the expression of MMP-2 by the periodontal cells.

Prostaglandin E2 enhances alveolar bone formation in the rat mandible.

Prostaglandin E2 (PGE2) induces bone formation in stress-bearing bones. The mandible, a stress-bearing bone, is loaded daily during mastication. The aim of this study was to determine if PGE2 delivered locally to the mandible over 20 days enhances alveolar bone deposition. In 18 Lewis rats, controlled-release pellets containing PGE2 were implanted on the buccal aspect on the left-hand side of the mandible, mesial to the root of the first molar. Controlled-release pellets locally delivered 0.1, 0.05, or 0.025 mg/day of PGE2. The right side of the mandible was used as a matched control for each animal. Six sham-treated animals were implanted with a placebo pellet. On days 7 and 19, animals were injected with the bone markers tetracycline and calcein, respectively. On day 21, animals were sacrificed and undecalcified tissues obtained for morphometrical analysis. Morphometrical measurements were analyzed by paired t test to determine differences between the matched samples and one-way ANOVA to compare the different treatment groups. A significant increase in alveolar bone area was observed in mandibles treated with 0.1 and 0.05 mg/day when compared with matched controls and the placebo group. This was accompanied by a significant increase in alveolar bone height and width. The proportions of double-labeled surface (dLS), the mineral apposition rate (MAR), and bone formation rate (BFR) were significantly increased in mandibles treated with the two higher doses of PGE2. The proportion of resorptive surface (RS) was significantly reduced in these two groups. It is concluded that PGE2 induces alveolar bone formation in the mandible when locally delivered at a dose of 0.1 or 0.05 mg/day for 20 days.

Periodontal treatment needs in a native island community in Colombia determined with CPITN.

AIMS: To identify the prevalence and different degrees of periodontal disease in an isolated community (Isla Grande, Colombia) with no dental services and low educational level with the use of CPITN, and to establish periodontal treatment needs in different age groups. RESULTS: Of 116 people examined, 0.9% were in periodontal health (CPITN value 0), 18.1% had gingival bleeding (CPITN value 1), 51.7% had supra or subgingival calculus (CPITN value 2), 18.1% presented pockets 3.5-5.0 mm deep (CPITN value 3), and 11.2% had pathological pockets of 5.5mm or deeper (CPITN value 4). No clear differences were observed between sexes. CONCLUSIONS: This study shows that 81% of the sample has some type of periodontal treatment need, with 69.8% of them requiring periodontal treatment that may be supplied by a hygienist and 11.2% requiring specialised treatment. Implementation of oral health education and oral prevention programmes was recommended to the authorities for this community.

Incisor disocclusion in rats affects mandibular condylar cartilage at the cellular level.

UNLABELLED: The effect of altered occlusion on the mandibular condylar cartilage remains unclear. OBJECTIVE: This study investigated the effect of unilateral incisor disocclusion on cartilage thickness, on mitotic activity and on chondrocytes maturation and differentiation in the mandibular condylar cartilage of rats. DESIGN: The upper and lower left incisors were trimmed 2mm every second day in five rats. In other five rats, the incisor occlusion was not altered. Condylar tissues from both sides of each mandible were processed and stained for Herovici's stain and immunohistochemistry for bromodeoxyuridine (BrdU), transforming growth factor-beta1 (TGF-beta1), alkaline phosphatase (ALP) and osteocalcin (OCN). Measurements of cartilage thickness and the numbers of immunopositive cells for each antibody were analysed by one-way analysis of variance (ANOVA). RESULTS: No significant differences were observed in cartilage thickness after 7 days of unilateral incisor disocclusion. However, the numbers of immunopositive cells for BrdU as a marker of DNA synthesising cells, TGF-beta1 as a marker of chondrocytes differentiation, and ALP and OCN as markers of chondrocytes maturation, were significant higher in the cartilage cells on both sides when incisor occlusion was unilaterally altered. Interestingly, alkaline phosphatase was highly expressed on the condylar side of incisor disocclusion, whereas osteocalcin was highly expressed on the side opposite to the incisor disocclusion. CONCLUSIONS: It is demonstrated that after 7 days, unilateral incisor disocclusion affects the mandibular condylar cartilage at the cellular level by increasing the mitotic activity and by accelerating chondrocytes maturation. Chondrocytes maturation appears more accelerated on the side opposite to incisor disocclusion.