Multivariate statistical analysis of chemical and electrochemical oscillators for an accurate frequency selection.

The effect of experimental parameters on the frequency of chemical oscillators has been systematically studied since the first observations of clock reactions. The approach is mainly based on univariate changes in one specific parameter while others are kept constant. The frequency is then monitored and the effect of each parameter is discussed separately. This type of analysis, however, does not take into account the multiple interactions among the controllable parameters and the synergic responses on the oscillation frequency. We have carried out a multivariate statistical analysis of chemical (BZ-ferroin catalyzed reaction) and electrochemical (Cu/Cu2O cathodic deposition) oscillators and identified the contributions of the experimental parameters on frequency variations. The BZ reaction presented a strong dependence on the initial concentration of sodium bromate and temperature, resulting in a frequency increase. The concentration of malonic acid, the organic substrate, affects the system but with lower intensity compared with the combination of sodium bromate and temperature. On the other hand, the Cu/Cu2O electrochemical oscillator was shown to be less sensitive to changes in the temperature. The applied current density and pH were the two parameters which most perturbed the system. Interestingly, the frequency behaved nonmonotonically with a quadratic dependence. The multivariate analysis of both oscillators exhibited significant differences - while the homogenous oscillator displayed a linear dependence with the factors, the heterogeneous one revealed a more complex dependence with quadratic terms. Our results may contribute, for instance, in the synthesis of self-organized materials in which an accurate frequency selection is required and, depending on its value, different physicochemical properties are obtained.

Orthodontic treatment need, self-esteem, and oral health-related quality of life among 12-yr-old schoolchildren.

The aim of this study was to investigate the association between orthodontic treatment need and oral health-related quality of life (OHRQoL) among 12-yr-old children. The study also assessed whether self-esteem modifies and/or moderates this relationship. Cross-sectional data on 406 schoolchildren aged 12 yr were analyzed. Data on socio-economic and demographic characteristics, dental pain, self-esteem, and OHRQoL were collected using validated questionnaires. Orthodontic treatment need was assessed, through dental examinations, using the dental aesthetic index (DAI). Multiple negative binomial regression and path analysis were used to estimate the association of orthodontic treatment need and self-esteem with OHRQoL. A modifying effect of self-esteem on the relationship between DAI and OHRQoL was observed. Self-esteem did not mediate the abovementioned relationship. Children with lower scores of self-esteem had worse OHRQoL among those with lower orthodontic treatment need (a DAI score of < 31). However, self-esteem did not influence the association between DAI and OHRQoL in children with greater orthodontic treatment need (a DAI score of ≥ 31). Self-esteem attenuated the impact of malocclusion on OHRQoL in children with minor or definite malocclusion, but not among those with severe or very severe malocclusion. Self-esteem appears to buffer the impact of malocclusion on OHRQoL in children with minor orthodontic treatment need.

Adjunctive effect of antimicrobial photodynamic therapy to nonsurgical periodontal treatment in smokers: a randomized clinical trial.

The aim of this study was to investigate the adjunctive effect of antimicrobial photodynamic therapy (aPDT) to scaling and root planing (SRP) in smokers with chronic periodontitis. Twenty subjects had two contralateral teeth randomly assigned to receive SRP (SRP group) or SRP + a single episode of aPDT (SRP + aPDT group), with a diode laser and a phenothiazine photosensitizer. Plaque index, bleeding on probing, probing depth (PD), clinical attachment level (CAL), and gingival recession were recorded, and gingival crevicular fluid was collected for assay of IL-1ß and matrix metalloproteinase (MMP)-8 levels. There was a significant PD reduction (SRP 1.81 ± 0.52 mm/SRP + aPDT 1.58 ± 1.28 mm; p < 0.001) and a significant CAL gain (SRP 1.60 ± 0.92 mm/SRP + aPDT 1.41 ± 1.58 mm; p < 0.001) for both groups. Significant differences were not observed in between-group comparisons. IL-1ß level in gingival crevicular fluid was higher in SRP group after 1 week (SRP 24.65 ± 18.85 pg/µL/SRP + aPDT 34.07 ± 24.81 pg/µL; p = 0.048), and MMP-8 level was higher in SRP group after 12 weeks (SRP 303.31 ± 331.62 pg/µL/SRP + aPDT 534.23 ± 647.37 pg/µL; p = 0.024). There were no statistically significant differences in intragroup comparisons. The adjunctive effect of aPDT did not warrant improvements on clinical parameters in smokers. However, it resulted in a suppression of IL-1ß and MMP-8 when compared with SRP alone.

Antimicrobial photodynamic therapy associated to nonsurgical periodontal treatment in smokers: microbiological results.

BACKGROUND: Studies suggest that smokers present more or greater numbers of potential periodontal pathogens than non-smokers. The aim of this study was to investigate the microbiologic effects of adjunctive aPDT on nonsurgical periodontal treatment in smokers with chronic periodontitis (CP). METHODS: Twenty smokers with CP had two contralateral teeth randomly assigned in a split-mouth design to receive SRP (CG) or SRP + a single episode of aPDT (TG), with a diode laser and a phenothiazine photosensitizer. Levels of 40 subgingival species were measured using checkerboard DNA-DNA hybridization at baseline and 1, 4 and 12 weeks after periodontal treatment. RESULTS: All 40 bacterial species evaluated were detected in different levels at baseline, with no statistic significant differences between groups. After periodontal treatment, the levels of some bacterial species decreased, while some other species presented an increase. Despite this variation, the statistical analysis was not able to identify significant differences neither at intragroup nor at intergroup comparisons. CONCLUSION: Periodontal treatment with SRP or SRP + aPDT was not able to reduce levels of 40 subgingival species in smokers with CP. These outcomes indicate that smoking impairs periodontal healing after nonsurgical treatment even associated with aPDT.

Buccal bone plate remodeling after immediate implants with or without synthetic bone grafting and flapless surgery: a histomorphometric and fluorescence study in dogs.

OBJECTIVE: The aim of this study was to evaluate the buccal bone plate remodeling after immediate implantation using the flapless approach with or without bone graft into the gap between the implant and the buccal bone. MATERIAL AND METHODS: Eight dogs had the mandibular bicuspids extracted without flaps, and four implants were installed on each side, totaling eight implants per animal. Randomly, in one side, the implants were positioned at the bone crest level (equicrestal), and on the opposite side, the implants were positioned 2 mm subcrestal. All the implants were positioned 2.0 mm from the buccal bone plate (gap) and associated or not with grafting material. Therefore, the following treatments were performed: implants subcrestal test (SCTG) with bone graft and control (SCCG) without bone graft, and equicrestal test (ECTG) with bone graft and control (ECCG) without bone graft. One week following the surgeries, metallic prostheses were installed. Bone markers were administered 1, 2, 4, and 12 weeks after implant placement for fluorescence analysis. Ground sections were prepared from 12-week healing biopsies, and histomorphometry was performed. RESULTS: The histomorphometric evaluation presents significant better results for the ECTG in the vertical crestal bone resorption, but the other parameters showed better results for the SCCG. The fluorescence evaluation in adjacent areas showed numerically different results between groups with a small decrease at 12 weeks, except for the SCCG, which was higher at this time. The distant area showed a continuous increase in the marked bone. CONCLUSION: The equicrestally placed implants presented little or no loss of the buccal bone wall. The subcrestally positioned implants presented loss of buccal bone, regardless of the use of bone graft. However, the buccal bone was always coronal to the implant shoulder. Both the equicrestal and subcrestal groups were benefited in the early stages of bone healing as evidenced by the fluorescence analysis.

Treatment of intrabony defects with anorganic bone matrix/p-15 or guided tissue regeneration in patients with aggressive periodontitis.

Intrabony periodontal defects present a particular treatment problem, especially in patients with generalized aggressive periodontitis (G-AgP). Regenerative procedures have been indicated for this clinical situation. The aim of this study was to compare treatment outcomes of intrabony periodontal defects with either anorganic bone matrix/cell binding peptide (ABM/P-15) or guided tissue regeneration (GTR) in patients with G-AgP. Fifteen patients, with two intrabony defects ≥3 mm deep, were selected. Patients were randomly allocated to be treated with ABM/P-15 or GTR. At baseline and at 3 and 6 months after surgery, clinical and radiographic parameters and IL-1ß and IL-6 gingival fluid concentrations were recorded. There was a significant probing pocket depth reduction (p<0.001) for both groups (2.27 ± 0.96 mm for ABM/P-15 group and 2.57 ± 1.06 mm for GTR group). Clinical attachment level gain (1.87 ± 0.94 mm for ABM/P-15 group and 2.09 ± 0.88 mm for GTR group) was also observed. There were no statistically significant differences in clinical parameters between the groups. The radiographic bone fill was more expressive in ABM/P-15 group (2.49 mm) than in GTR group (0.73 mm). In subtraction radiographs, the areas representing gain in density were 93.16% of the baseline defect for ABM/P-15 group versus 62.03% in GRT group. There were no statistically significant differences in inter-group and intra-group comparisons with regards to IL-1ß and IL-6 quantification. Treatment of intrabony periodontal defects in patients with G-AgP with ABM/P-15 and GTR improved significantly the clinical outcomes. The use of ABM/P-15 promoted a better radiographic bone fill.

Treatment of Intrabony Defects with Anorganic Bone Matrix/P-15 or Guided Tissue Regeneration in Patients with Aggressive Periodontitis

Intrabony periodontal defects present a particular treatment problem, especially in patients with generalized aggressive periodontitis (G-AgP). Regenerative procedures have been indicated for this clinical situation. The aim of this study was to compare treatment outcomes of intrabony periodontal defects with either anorganic bone matrix/cell binding peptide (ABM/P-15) or guided tissue regeneration (GTR) in patients with G-AgP. Fifteen patients, with two intrabony defects ≥3 mm deep, were selected. Patients were randomly allocated to be treated with ABM/P-15 or GTR. At baseline and at 3 and 6 months after surgery, clinical and radiographic parameters and IL-1β and IL-6 gingival fluid concentrations were recorded. There was a significant probing pocket depth reduction (p<0.001) for both groups (2.27 ± 0.96 mm for ABM/P-15 group and 2.57 ± 1.06 mm for GTR group). Clinical attachment level gain (1.87 ± 0.94 mm for ABM/P-15 group and 2.09 ± 0.88 mm for GTR group) was also observed. There were no statistically significant differences in clinical parameters between the groups. The radiographic bone fill was more expressive in ABM/P-15 group (2.49 mm) than in GTR group (0.73 mm). In subtraction radiographs, the areas representing gain in density were 93.16% of the baseline defect for ABM/P-15 group versus 62.03% in GRT group. There were no statistically significant differences in inter-group and intra-group comparisons with regards to IL-1β and IL-6 quantification. Treatment of intrabony periodontal defects in patients with G-AgP with ABM/P-15 and GTR improved significantly the clinical outcomes. The use of ABM/P-15 promoted a better radiographic bone fill.

Defeitos periodontais infra-ósseos representam um desafio particular no tratamento, especialmente em pacientes com periodontite agressiva generalizada (PAg-G). Procedimentos regenerativos tem sido indicados para esta situação clínica. O objetivo deste estudo foi comparar os resultados do tratamento de defeitos periodontais infra-ósseos com associação de matriz óssea inorgânica bovina com o P-15 (MOI/P-15) ou regeneração tecidual guiada (RTG) em pacientes com PAg-G. 15 pacientes com PAg-G, com pelo menos dois defeitos periodontais infra-ósseos (profundidade de sondagem ≥4 mm e componente infra-ósseo ≥3 mm) foram selecionados. Os pacientes foram aleatoriamente alocados para serem tratados com MOI/P-15 ou RTG. No exame inicial, e aos 3 e 6 meses após a cirurgia, os parâmetros clínicos e radiográficos e as concentrações de IL-1β e IL-6 no fluido gengival foram registrados. Houve uma redução significativa profundidade de sondagem (p<0,001) para ambos os grupos (2,27 ± 0,96 mm para o grupo MOI/P-15 e 2,57 ± 1,06 mm para o grupo RTG). Um ganho no nível clínico de inserção (1,87 ± 0,94 mm para o grupo MOI/P-15 e 2,09 ± 0,88 mm para o grupo RTG) também foi observado. Na comparação entre grupos, não houve diferenças estatisticamente significativas nos parâmetros clínicos. O preenchimento ósseo radiográfico foi mais expressivo no grupo MOI/P-15 (2,49 mm) do que no grupo RTG (0,73 mm). Na análise radiográfica, as radiografias de subtração apresentaram ganho médio de área radiopaca em relação ao defeito inicial de 93,16% para grupo MOI/P-15, contra 62,03% para o grupo RTG. Na análise das citocinas, não foram observadas diferenças estatisticamente significantes nas comparações intra e entre os grupos. O tratamento de defeitos infra-ósseos com MOI/P-15 ou RTG em pacientes com PAg-G, em um período de 6 meses, levou a melhoras nos parâmetros clínicos. O uso de MOI/P-15 levou a um maior preenchimento radiográfico.

Enamel matrix derivative and transforming growth factor-beta1 in Class III furcation defects. A histomorphometric study in dogs.

The objective of this study was to evaluate histomorphometrically, in dogs, the effect of enamel matrix derivative (EMD), with or without transforming growth factor-beta1 (TGF-beta1), in a periodontal Class III furcation model. Class III furcation defects were created in P3 and P4 of six dogs. The defects were allowed to stabilize for 21 days. Four experimental conditions were established: G1: control (propylene glycol alginate); G2: EMD; G3: TGF-beta1 and G4: EMD + TGF-beta1. After 12 weeks, the dogs were euthanized. Their jaws were removed, fixed, decalcified, dehydrated and embedded in paraffin. Semi-serial sections were obtained, stained and examined with light microscopy. The furcation defects were not completely closed in any specimen, with downgrowth of the junctional epithelium into the furcation area. The morphologic characteristics of the newly formed tissues in the test groups were similar to the control group, with slight differences in average values, but with no statistically significant differences between the groups. This study was not able to provide histological evidence that EMD, TGF-beta1 and EMD + TGF-beta1 present additional advantages in periodontal bone formation in a Class III furcation model in dogs.

Buccal bone plate remodeling after immediate implant placement with and without synthetic bone grafting and flapless surgery: radiographic study in dogs.

Recent studies in animals have shown pronounced resorption of the buccal bone plate after immediate implantation. The use of flapless surgical procedures prior to the installation of immediate implants, as well as the use of synthetic bone graft in the gaps represent viable alternatives to minimize buccal bone resorption and to favor osseointegration. The aim of this study was to evaluate the healing of the buccal bone plate following immediate implantation using the flapless approach, and to compare this process with sites in which a synthetic bone graft was or was not inserted into the gap between the implant and the buccal bone plate. Lower bicuspids from 8 dogs were bilaterally extracted without the use of flaps, and 4 implants were installed in the alveoli in each side of the mandible and were positioned 2.0 mm from the buccal bone plate (gap). Four groups were devised: 2.0-mm subcrestal implants (3.3 × 8 mm) using bone grafts (SCTG), 2.0-mm subcrestal implants without bone grafts (SCCG), equicrestal implants (3.3 × 10 mm) with bone grafts (ECTG), and equicrestal implants without bone grafts (ECCG). One week following the surgical procedures, metallic prostheses were installed, and within 12 weeks the dogs were sacrificed. The blocks containing the individual implants were turned sideways, and radiographic imaging was obtained to analyze the remodeling of the buccal bone plate. In the analysis of the resulting distance between the implant shoulder and the bone crest, statistically significant differences were found in the SCTG when compared to the ECTG (P = .02) and ECCG (P = .03). For mean value comparison of the resulting linear distance between the implant surface and the buccal plate, no statistically significant difference was found among all groups (P > .05). The same result was observed in the parameter for presence or absence of tissue formation between the implant surface and buccal plate. Equicrestally placed implants, in this methodology, presented little or no loss of the buccal bone. The subcrestally positioned implants presented loss of buccal bone, even though synthetic bone graft was used. The buccal bone, however, was always coronal to the implant shoulder.