Rehabilitation of atrophic maxilla: a review of 101 zygomatic implants

Introduction: Zygomatic implants are a good rehabilitation alternative for upper maxilla with severe bone reabsorption. These implants reduce the need for onlay-type bone grafting in the posterior sectors and for maxillary sinus lift procedures - limiting the use of bone grafts to the anterior zone of the upper jaw in those cases where grafting is considered necessary. Objective: To evaluate the survival of 101 zygomatic implants placed in upper maxilla presenting important bone reabsorption, with a follow-up of 1-72 months. Patients and methods: A retrospective study was made of 101 Zygoma® implants (Nobel Biocare, Göteborg, Sweden) placed in 54 patients with totally edentulous and atrophic upper maxilla, in the period between 1998-2004. There were 35 women and 19 men, subjected to rehabilitation in the form of fixed prostheses and overdentures using 1-2 zygomatic implants and 2-7 implants in the anterior maxillary zone. The principal study variables were smoking, a history of sinusitis, the degree of bone reabsorption, and peri-implant bone loss, among others. Results: The descriptive analysis of the 101 zygomatic implants placed in 54 patients with a mean age of 56 years (range 38-75) yielded a percentage survival of 96.04%, with four failed implants that were removed (two before and two after prosthetic loading). Nine patients were smokers, and none of the 54 subjects reported a history of sinus disorders. Discussion and conclusions: Zygomatic implants are designed for use in compromised upper maxilla. They allow the clinician to shorten the treatment time, affording an interesting alternative for fixed prosthetic rehabilitation. This study confirms that zygomatic bone offers predictable anchorage and acceptable support function for prostheses in atrophic jaws. However, these implants are not without complications. Longer-term evaluations are needed of zygomatic implant survival in order to establish a correct clinical prognosi

Endosseous dental implant fractures an analysis of 21 cases

Implant fracture is an infrequent cause of implant failure. The present study evaluates 21 fractured implants, with an analysis of patient age and sex, the type, length and diameter of the implant, positioning in the dental arch, the type of prosthetic rehabilitation involved, the number of abutments and pontics, the presence or absence of distal extensions or cantilevers, and loading time to fracture. Implant fracture was more common in males than in females (15:4), and the mean patient age was 56.9 years. Most cases (n = 19) corresponded to implant-supported fixed prostheses - 16 with cantilevers of different lengths ? while only two fractured implants were supporting overdentures instead of fixed prostheses. The great majority of fractured implants (80.9%) were located in the molar and premolar regions, and most fractured within 3-4 years after loading. It is important to know and apply the measures required to prevent implant fracture, and to seek the best individualized solution for each case - though complete implant removal is usually the treatment of choice

Assessment of bone-regeneration using adipose-derived stem cells in critical-size alveolar ridge defects: an experimental study in a dog model

Purpose: To assess bone regeneration potential of a fibronectin- and adipose-derived stem cell-covered ceramic biomaterial in three-wall critical size alveolar ridge defects. Materials and methods: In 18 dogs, four dehiscence-type and critical size defects were created surgically in the edentulous alveolar ridge. Defects were randomly regenerated using biomaterials coated with particulate ß-tricalcium phosphate (ß-TCP), ß-TCP with fibronectin (Fn) (ß-TCP-Fn), and ß-TCP with a combination of Fn and autologous adipose-derived stem cells (ADSCs) (ß-TCP-Fn-ADSCs), leaving one defect as control. The animals were divided into three groups according to the time of euthanasia (1, 2, or 3 months of healing). Results: At the time of sacrifice, statistically significant differences between the four types of defects in the total area of bone regeneration, percentage of neoformed bone matrix, medullary space, or contact between particulate biomaterial and neoformed bone matrix were not found. All defects showed a significant increase in neoformed bone matrix as sacrifice was delayed, but a uniform pattern was not followed. Only defects treated with ß-TCP-Fn-ADSCs showed a significant increase in the bone regeneration area when animals sacrificed at 3 months were compared to those sacrificed at 1 month (P = .006). Conclusion: The use of ADSCs in bone regeneration processes of critical size defects of the alveolar ridge did not entail an advantage regarding greater bone regeneration as compared with other biomaterials. However, the use of ß-TCP coated with a combination of Fn and ADSCs appeared to favor stabilization of the regenerated area, allowing a more efficient maintenance of the space at 3 months of healing

Metastable polymorphic phases in monolayer TaTe2

Polymorphic phases and collective phenomena—such as charge density waves (CDWs)—in transition metal dichalcogenides (TMDs) dictate the physical and electronic properties of the material. Most TMDs naturally occur in a single given phase, but the fine-tuning of growth conditions via methods such as molecular beam epitaxy (MBE) allows to unlock otherwise inaccessible polymorphic structures. Exploring and understanding the morphological and electronic properties of new phases of TMDs is an essential step to enable their exploitation in technological applications. Here, scanning tunneling microscopy (STM) is used to map MBE-grown monolayer (ML) TaTe2. This work reports the first observation of the 1H polymorphic phase, coexisting with the 1T, and demonstrates that their relative coverage can be controlled by adjusting synthesis parameters. Several superperiodic structures, compatible with CDWs, are observed to coexist on the 1T phase. Finally, this work provides theoretical insight on the delicate balance between Te…Te and Ta–Ta interactions that dictates the stability of the different phases. The findings demonstrate that TaTe2 is an ideal platform to investigate competing interactions, and indicate that accurate tuning of growth conditions is key to accessing metastable states in TMD

La educación social en los extremos: justicia social y paradojas de la práctica

Presentación de la obra colectiva La Educación Social en los extremos: justicia social y paradojas de la práctica en la que se abordan desde diversas perspectivas y miradas las paradojas de y en la Educación social afirmando que, según nuestro parecer, es necesario tener una visión positiva de las contradicciones y de las paradojas existentes en el campo de la educación social, pues dichas paradojas y contradicciones son necesarias para el debate y el progreso de dicho campo disciplinar. Ello implica no entenderlas como un juego de contrarios o una oposición que no es resoluble sin la negación de una de las partes, sino que deben abordarse desde una perspectiva integrativa y deliberativa. Debemos entenderlas en clave dialéctica, considerándolas como una oposición en la que los diversos términos implican una parte de su opuesto, al estilo de las filosofías orientales, tan diferentes del racionalismo y del maniqueísmo occidentales modernos