A possible novel objective intraoperative measurement of maxillary bone density.

AIM: Implant survival and success rates are strictly related to the density of the bone they are placed in. Bone density, in fact, affects both implant primary stability and implant micromovements after implant positioning. Current bone density classifications rely on subjective, scarcely reproducible evaluations. A novel implant micro motor featuring a bone density measurement probe has been recently introduced. The objective of this study was to test such bone density measurement system for its capability of distinguishing different bone density areas in the upper and in the lower jaw. METHODS: 1254 implant placement sites had their bone density measured during standard implant placement at a single clinical facility. After data collection bone density distribution was statistically analyzed in order to test the hypothesis of a non-homogeneous distribution in four different predefined anatomical maxillary zones, namely pre-antral (between teeth from 14 to 24) and sub-antral (more distally) in the upper maxilla and interforaminal (between and including teeth from 34 to 44) and retroforaminal (more distally) zone. RESULTS: Measured bone density values, organized according the named four anatomical zones, produced a statistically significant inhomogeneous pattern (P<0.001). Density distribution was consistent with data from literature, but not always corresponding with the one achieved by applying the well known Misch classification. CONCLUSION: The measuring system we tested allowed to distinguish different and clinically significant anatomical zones according to their different bone density, and can represent a fundamental diagnostic tool to plan the proper implant placement steps.

Two color free-electron laser and frequency beating.

We review the theory of two color high gain free-electron laser emission, derive the integral equation characterizing the evolution of the optical intensities, and provide a description of the relevant dynamics. The characteristic feature of this regime is the existence of a mutual bunching, whose origin and role are discussed.

Cancer metabolism and the dynamics of metastasis.

Cancer growth dynamics, commonly simulated with a Gompertzian model, is analyzed in the framework of a more recent and realistic model. In particular, we consider the setting of a tumor embedded in a host organ and investigate their interaction. We assume that, at least in some cases, tumor metastasis may be triggered by an 'energetic crisis', when the tumor exceeds the 'carrying capacity' of the host organ. As a consequence, dissemination of clusters of cancer cells is set in motion, with a statistical probability given by a Poisson distribution. The model, although still at a preclinical level, is fully quantitative and is applied, as an example, to the case of prostate cancer. The results confirm that, at least for the more aggressive cancers, metastasis starts very early during tumorigenesis and a quantitative link is found between the tumor's doubling time, its 'aggressiveness' and the metastatic potential.

Maxillary sinus lift through heterologous bone grafts and simultaneous acid-etched implants placement. Five year follow-up.

AIM: The aim of this study was to assess retrospectively at 5 years the clinical outcome of bone regeneration in patients who underwent maxillary sinus lift with different equine-derived, enzyme-deantigenated equine bone grafts, and simultaneous placement of acid-etched surface implants. METHODS: Eighteen patients (10 males and 8 females, age between 55 and 61 years) were considered. They were divided into 2 groups according to the type of bone graft used: a combination of an equine flexible heterologous spongy bone layer (Osteoplant Flex, Bioteck) and equine heterologous cortical and spongy granules (Bio-Gen Mix, Bioteck), group A, or a block of equine heterologous spongy bone (Bio-Gen Block, Bioteck), group B. Surface-treated implants (''TRE'' type, Biotec) were placed simultaneously to sinus augmentations and usual clinical and radiological tests were performed at 6 months and every year up to 5 years after surgery. RESULTS: At 5 years, 45 out of 49 total implants placed (91.8%) were successful according to the Albrektsson and Zarb criteria. The loss of the 4 failed implants was observed in 2 patients of group B during the first days following surgery. CONCLUSION: These results show that the heterologous bone grafts supported properly the bone regeneration inside the sinuses, and that the type of implants used allowed to achieve a satisfying rate of success according to the current standards in implantology.

Complete loss of P/Q calcium channel activity caused by a CACNA1A missense mutation carried by patients with episodic ataxia type 2.

Familial hemiplegic migraine, episodic ataxia type 2 (EA2), and spinocerebellar ataxia type 6 are allelic disorders of the CACNA1A gene (coding for the alpha(1A) subunit of P/Q calcium channels), usually associated with different types of mutations (missense, protein truncating, and expansion, respectively). However, the finding of expansion and missense mutations in patients with EA2 has blurred this genotype-phenotype correlation. We report the first functional analysis of a new missense mutation, associated with an EA2 phenotype-that is, T-->C transition of nt 4747 in exon 28, predicted to change a highly conserved phenylalanine residue to a serine at codon 1491, located in the putative transmembrane segment S6 of domain III. Patch-clamp recording in HEK 293 cells, coexpressing the mutagenized human alpha(1A-2) subunit, together with human beta(4) and alpha(2)delta subunits, showed that channel activity was completely abolished, although the mutated protein is expressed in the cell. These results indicate that a complete loss of P/Q channel function is the mechanism underlying EA2, whether due to truncating or to missense mutations.