143 research outputs found

    Factors that influence the position of the peri-implant soft tissues: a review

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    Introduction: The implantological rehabilitation of the anterior sector is one of the most demanding and complex treatments due to the necessity of obtaining an optimum esthetic result. At the level of the soft tissues, it involves obtaining the complete formation of the papilla and creating a harmonic contour of the gingival margin.Objective: A bibliographical review has been carried out on the factors that influence the final position of the soft tissues.Material and methods: A search has been carried out in the Pubmed database of articles written in English and Spanish. Articles that presented a clinical series of less than five patients and a monitoring of less than one year were excluded.Results: At the level of the papilla, there are two decisive factors that play an influential role: the formation of the biological width and the distance between the alveolar crest and the contact point. The position of the gingival margin depends mainly of the height and width of the facial bone, as well as on the biotype. The surgical technique, as well as certain prosthodontics aspects related to the implant, can influence the final position of the soft tissues.Conclusions: Although, today we know much more about the factors that influence the position of the soft tissues, there are still certain aspects that should be studied more in-depth, for example the influence of the micro and macro-structure of the implant in the position of the soft tissues

    Resonance estimates for single spin asymmetries in elastic electron-nucleon scattering

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    We discuss the target and beam normal spin asymmetries in elastic electron-nucleon scattering which depend on the imaginary part of two-photon exchange processes between electron and nucleon. We express this imaginary part as a phase space integral over the doubly virtual Compton scattering tensor on the nucleon. We use unitarity to model the doubly virtual Compton scattering tensor in the resonance region in terms of γNπN\gamma^* N \to \pi N electroabsorption amplitudes. Taking those amplitudes from a phenomenological analysis of pion electroproduction observables, we present results for beam and target normal single spin asymmetries for elastic electron-nucleon scattering for beam energies below 1 GeV and in the 1-3 GeV region, where several experiments are performed or are in progress.Comment: 36 pages, 16 figure

    Bottom quark mass and QCD duality

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    The mass of the bottom quark is analyzed in the context of QCD finite energy sum rules. In contrast to the conventional approach, we use a large momentum expansion of the QCD correlator including terms to order alpha(S)(2)(m(b)(2)/q(2))(6) with the upsilon resonances from e(+)c(-) annihilation data as main input. A stable result m(b)(m(b)) = (4.19 +/- 0.05) GeV for the bottom quark mass is obtained. This result agrees with the independent calculations based on the inverse moment analysis

    A Sequential Inspection Procedure for Fault Detection in Multistage Manufacturing Processes

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    Fault diagnosis in multistage manufacturing processes (MMPs) is a challenging task where most of the research presented in the literature considers a predefined inspection scheme to identify the sources of variation and make the process diagnosable. In this paper, a sequential inspection procedure to detect the process fault based on a sequential testing algorithm and a minimum monitoring system is proposed. After the monitoring system detects that the process is out of statistical control, the features to be inspected (end of line or in process measurements) are defined sequentially according to the expected information gain of each potential inspection measurement. A case study is analyzed to prove the benefits of this approach with respect to a predefined inspection scheme and a randomized sequential inspection considering both the use and non-use of fault probabilities from historical maintenance data

    QCD sum rule determination of the charm-quark mass

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    QCD sum rules involving mixed inverse moment integration kernels are used in order to determine the running charm-quark mass in the MS¯ scheme. Both the high and the low energy expansion of the vector current correlator are involved in this determination. The optimal integration kernel turns out to be of the form p(s)=1−(s0/s)2, where s0 is the onset of perturbative QCD. This kernel enhances the contribution of the well known narrow resonances, and reduces the impact of the data in the range s≃20−25GeV2. This feature leads to a substantial reduction in the sensitivity of the results to changes in s0, as well as to a much reduced impact of the experimental uncertainties in the higher resonance region. The value obtained for the charm-quark mass in the MS¯ scheme at a scale of 3 GeV is m¯c(3GeV)=987±9MeV, where the error includes all sources of uncertainties added in quadrature

    Pediatric oral ranula : clinical follow-up study of 57 cases

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    Objective: To present 57 cases of oral ranula in children, analyzing the clinical characteristics, treatment and outcome of these lesions. Methods: The clinical histories of patients diagnosed with oral ranula, seen between 1998 and 2008 at the Oral and Maxillofacial Surgery Unit of a reference Children?s Hospital (0-14 years) were reviewed. All patients with clinical diagnosis of oral ranula were included. Results: Fifty-seven patients, 21 boys and 36 girls, with a mean age of 5.1 years were included in the study. Thirtytwo cases were located on the left side of the floor of the mouth. The lesion diameter varied between 1 and 3 cm in 27 cases, 22 were less than 1 cm, and 8 were larger than 3 cm. Fifty-four cases were asymptomatic and 3 ranulas had pain on swallowing. Twenty-two cases were resolved by opening with a tract dilator and 35 by marsupialization. Seven cases recurred at a mean of 12 months after treatment, three of these from the marsupialization group. Conclusion: The majority of the oral ranulas occurred in females, asymptomatic, on the left side of the floor of the mouth, with a mean size of 1 to 3 cm; all lesions were treated by surgery, of which 7 recurred

    Orofacial dermoid cysts in pediatric patients : a review of 8 cases

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    Objective: The aim was to analyze the clinical characteristics, treatment and outcome of 8 orofacial dermoid cysts (DC) in pediatric patients. Material and Methods: A retrospective observational study was made, reviewing the medical records with clinical diagnosis of dermoid cyst between 1987 and 2006 in the Children?s Maxillofacial Surgery Department of the Hospital Universitario La Fe, Valencia, Spain. The following data were collected: sex, age, location, size and duration of the lesion, treatment, length of follow-up, and recurrence. Results: Eight patients (3 girls and 5 boys) with a mean age of 2.7 years (range 0-12 years). Four DC were located in the oral area (3 sublingual and 1 lingual), one in the periorbital and three in the nasal areas. The size ranged from 0.8 cm to 4 cm. The mean duration of the lesion was 13.7 months (range 4 days to 2 years). All DC were diagnosed pathologically following surgical removal of the lesion. There were no recurrences. Conclusion: The appearance of DC in the maxillofacial region of pediatric patients is uncommon. The floor of the mouth is the most frequently affected area in the oral cavity. Treatment is surgical removal of the lesion. Recurrence is unusual

    Chiral corrections to the SU(2)×SU(2)SU(2)\times SU(2) Gell-Mann-Oakes-Renner relation

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    The next to leading order chiral corrections to the SU(2)×SU(2)SU(2)\times SU(2) Gell-Mann-Oakes-Renner (GMOR) relation are obtained using the pseudoscalar correlator to five-loop order in perturbative QCD, together with new finite energy sum rules (FESR) incorporating polynomial, Legendre type, integration kernels. The purpose of these kernels is to suppress hadronic contributions in the region where they are least known. This reduces considerably the systematic uncertainties arising from the lack of direct experimental information on the hadronic resonance spectral function. Three different methods are used to compute the FESR contour integral in the complex energy (squared) s-plane, i.e. Fixed Order Perturbation Theory, Contour Improved Perturbation Theory, and a fixed renormalization scale scheme. We obtain for the corrections to the GMOR relation, δπ\delta_\pi, the value δπ=(6.2,±1.6)\delta_\pi = (6.2, \pm 1.6)%. This result is substantially more accurate than previous determinations based on QCD sum rules; it is also more reliable as it is basically free of systematic uncertainties. It implies a light quark condensate 2GeV=(267±5MeV)3 \simeq \equiv |_{2\,\mathrm{GeV}} = (- 267 \pm 5 MeV)^3. As a byproduct, the chiral perturbation theory (unphysical) low energy constant H2rH^r_2 is predicted to be H2r(νχ=Mρ)=(5.1±1.8)×103H^r_2 (\nu_\chi = M_\rho) = - (5.1 \pm 1.8)\times 10^{-3}, or H2r(νχ=Mη)=(5.7±2.0)×103H^r_2 (\nu_\chi = M_\eta) = - (5.7 \pm 2.0)\times 10^{-3}.Comment: A comment about the value of the strong coupling has been added at the end of Section 4. No change in results or conslusion

    Clinical characteristics, treatment and outcome of 28 oral haemangiomas in paediatric patients

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    Objective: To present a large series of oral haemangiomas in children, analyzing the clinical characteristics, treatment and outcome of oral haemangiomas in 28 children. Material and Methods: We conducted an observational retrospective study, reviewing medical records with clinical diagnosis of haemangioma between 1990 and 2006 at the Children?s Maxillofacial Surgery Service of the Hospital Universitario la Fe, Valencia. All patients with a clinical, radiographic, pathologically confirmed diagnosis of oral haemangioma were included. Results: The study included 28 patients (19 females and 9 males) with a mean age of 4.27 years (range 0-14 years). Nine were congenital haemangioma. The most frequent location of oral haemangioma was in the lip with 23 cases, followed by three cases in the tongue and 2 in the buccal mucosa. The mean diameter of the lesion was 1.67 cm (range 1-3cm). The mean duration of the lesion was 6.3 months (range 1 month to 5 years). Of the 28 haemangiomas, 13 were surgically removed, 2 were treated with embolization and 13 disappeared spontaneously. The mean follow up was 2.7 months (1-8 months). There were no cases of recurrence. Conclusions: Haemangiomas usually present in children, and can be seen from birth. They have a predilection for females. They are uncommon in the oral cavity. In the oral region, the most common location is the lip. Most congenital haemangioma regress spontaneously without treatment. The treatment of choice is surgical excision of the lesion
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