Pablo Galindo

Immediate implant loading: current status from available literature.

The introduction of osseointegrated implants in dentistry represents a turning point in dental clinical practice. Thanks to their multiple therapeutic possibilities and the high predictability of success, implant therapy is now regarded as an extremely reliable approach to replace missing teeth. The concept of immediate implant loading has recently become popular due to less trauma, reduced overall treatment time, decreased patients anxiety and discomfort, high patient acceptance and better function and esthetics. Nonetheless, research and understanding in this area are confuse and sometimes contradictory. Hence, it is the purpose of this review to provide rational for immediate implant loading, summarize current available literature, and analyze factors that influencing this newly introduced treatment method. Results from this review indicated that immediate implant loading achieved similar high success rate as that noted in the conventional approach (delayed protocols). However, a careful case selection, proper treatment plan, meticulous surgery and proper design of prosthesis are essential for optimal outcomes when this approach is adopted.

The influence of remaining alveolar bone upon lateral window sinus augmentation implant survival

Background of Problems:Sinus augmentation is a predictable procedure to increase bone height in the posterior maxilla to facilitate ideal implant placement. However, the effect of residual alveolar bone height upon overall implant success remains unclear. Aims:Hence, the objective of this study was to review and evaluate the correlation between amount of remaining crest alveolar bone before sinus augmentation and implant survival rate in grafted areas. Materials:Medline search was used to identify articles published through September 2006, with preset selection criteria. Results:A total of 156 peer-reviewed publications were selected. Eighteen publications fulfilled the selection criteria. Despite the great het erogeneity found among the selected studies, we were able to group the selected articles in 2 distinct groups and show average implant survival rate in the following residual bone categories: (1) <5 mm: 96% (80%–100%); and (2) >4 mm 99% (97%–100%). Conclusion:The data reviewed from the literature suggests a higher implant survival predictability as available residual bone increases. However, prospective studies with adequate sample size and control of confounding factors are needed to validate this observation.

Significance of p53 expression in non-tumoral epithelium adjacent to oral squamous cell carcinomas

Alterations of the p53 gene are the most frequently documented genetic abnormalities in human cancer. The aim of the present study was to analyse if this alteration is an early event in oral tumorigenesis and if the suprabasal expression of p53 is a marker of the presence and severity of epithelial dysplasia. Immunohistochemical p53 expression in 78 specimens of oral squamous cell carcinoma and non-tumoral adjacent epithelium was analysed. Non-tumoral epithelium was observed in 53 cases (67.9 per cent), being normal in six cases (7.6 per cent), hyperplastic in 24 cases (30.7 per cent) and dysplastic in 48 cases (61.5 per cent). Epithelial dysplasia was mild (23 cases, 47.9 per cent); moderate (23 cases, 47.9 per cent) and severe (two cases, 4.1 per cent). Twenty-one cases of the dysplasias (43.8 per cent) expressed p53. No p53 expression appeared in any normal epithelium. Basal p53 expression always appeared in mild dysplasias (two cases). Suprabasal p53 expression appeared in mild and moderate dysplasias in nine cases and in one severe dysplasia. No statistical correlation was observed between suprabasal expression of p53 and the presence or severity of the dysplasia. The expression of p53 is an early event in oral tumorigenesis but it does not behave as an objective marker of the presence or severity of epithelial dysplasia.

McGehee regularization of general SO(3)- invariant potentials and applications to stationary and spherically symmetric spacetimes

The McGehee regularization is a method to study the singularity at the origin of the dynamical system describing a point particle in a plane moving under the action of a power-law potential. It was used by Belbruno and Pretorius (2011 Class. Quantum Grav. 28 195007) to perform a dynamical system regularization of the singularity at the center of the motion of massless test particles in the Schwarzschild spacetime. In this paper, we generalize the McGehee transformation so that we can regularize the singularity at the origin of the dynamical system describing the motion of causal geodesics (timelike or null) in any stationary and spherically symmetric spacetime of Kerr–Schild form. We first show that the geodesics for both massive and massless particles can be described globally in the Kerr–Schild spacetime as the motion of a Newtonian point particle in a suitable radial potential and study the conditions under which the central singularity can be regularized using an extension of the McGehee method. As an example, we apply these results to causal geodesics in the Schwarzschild and Reissner–Nordstrom spacetimes. Interestingly, the geodesic trajectories in the whole maximal extension of both spacetimes can be described by a single two-dimensional phase space with non-trivial topology. This topology arises from the presence of excluded regions in the phase space determined by the condition that the tangent vector of the geodesic be causal and future directed.

Regularization of geodesics in static spherically symmetric Kerr-Schild spacetimes

We describe a method to analyze causal geodesics in static and spherically symmetric spacetimes of Kerr-Schild form which, in particular, allows for a detailed study of the geodesics in the vicinity of the central singularity by means of a regularization procedure based on a generalization of the McGehee regularization for the motion of Newtonian point particles moving in a power-law potential. The McGehee regularization was used by Belbruno and Pretorius to perform a dynamical system regularization of the central singularity of the motion of massless test particles in the Schwarzschild spacetime. Our generalization allows us to consider causal (timelike or null) geodesics in any static and spherically symmetric spacetime of Kerr-Schild form. As an example, we apply these results to causal geodesics in the Schwarzschild and Reissner-Nordstrom spacetimes.