Assessment of the correlation between implant stability and bone density by computed tomography and resonance frequency analysis in fresh cadavers.

PURPOSE: Because of the immediate loading implant process, clinicians must consider implant primary stability issues before initiating surgery. The aim of this study was to assess the correlation between the bone density assessed by computed tomography (CT) images and the primary stability of two implant designs, as determined by resonance frequency analysis (RFA). MATERIALS AND METHODS: Sixty implants (30 NobelActive, 30 NobelSpeedy [Nobel Biocare]) were placed in five totally edentulous fresh cadaver maxillae. Before surgery, CT images were analyzed and bone densities measured. Implant primary stabilities (measured in implant stability quotient [ISQ] units) were determined along the buccolingual and mesiodistal axes by RFA. Correlations were assessed using the Pearson correlation test. RESULTS: Bone densities were similar near NobelActive and NobelSpeedy implants: 434.67 (± 220.53) versus 479.87 (± 209.05) Hounsfield Units (HU). Bone densities and NobelActive primary stabilities were highly correlated with ρ = 0.74 (P = .000) and ρ = 0.78 (P = .000) for the buccolingual and mesiodistal axes, respectively. An association was found between the 350 HU and 50 ISQ values, confirming good primary stabilities. For NobelSpeedy implants, no correlation was found regardless of the axis, with ρ = -0.07 (P = .72) (buccolingual) and ρ = -0.10 (P = .59) (mesiodistal). However, poor and good stabilities were observed in the anterior and posterior areas, respectively. CONCLUSION: This study revealed variations in primary stabilities depending on the implant design. The primary stability of conical implants with a double-lead thread design (NobelActive) seemed bone density-dependent regardless of the area of the maxilla, whereas the primary stability of nearly parallel-wall implants with a classical thread design (NobelSpeedy) seemed dependent on anatomical morphology. These results raise questions about the specific roles of the implant shape and thread design depending on the bone density and alveolar morphology.

Ancient Down syndrome: An osteological case from Saint-Jean-des-Vignes, northeastern France, from the 5-6th century AD.

The pathological skull of a 5-7 year old child from Saint-Jean-des-Vignes (Saône-et-Loire, north-eastern France) dated to the 5-6th century AD is described. Morphological and radiographic features, metrical data and Computed Tomography (CT) scans are used to study the osteological abnormalities in comparison with normal skulls of individuals of similar age and geographic origin. The combination of features is consistent with the diagnosis of Down syndrome (e.g. brachycrany, metopism, hypodontia, periodontitis, a flattened occiput, vault thinness, and an open cranial base angle), although none is pathognomonic of the disease in isolation. Cases of Down syndrome in past populations are rare, frequently poorly described or discovered out of context. This case represents the earliest and youngest example of the condition in the archaeological record. The context and funerary treatment of this child suggests that he/she was not stigmatized by other members of the community, who afforded a normal mode of burial.