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The surface characteristics of dental implants play an important role in the osseointegration process. Over the years implant surfaces have been subjected to different treatments, including turning, plasma spraying, coating, sand blasting, acid etching, and anodization. FBR coating is a fully resorbable calcium phosphate (CaP) coating made of brushite, obtained by electrochemical deposition on titanium plasma-sprayed (TPS) implants; this bioactive layer may be totally resorbable in 6-12 weeks and once the FBR coating has been resorbed, the newly formed bone is in contact with the roughness of the TPS surface. Human biopsy of immediately-loaded implants is certainly the most definitive means of determining the occurrence of osseointegration. In this case series the histologic and histomorphometric features of the bone-implant interface are analyzed and discussed in 3 immediately restored implants, retrieved from human subjects at 8, 10 and 12 weeks, respectively. All 3 implants were osseointegrated, with a bone to implant contact (BIC) ranging from 54.4% to 70.1%. The FBR coating was resorbed and replaced by new bone. Osteoconduction was especially noticeable between the implant threads, where the pristine bone was removed during implant bed preparation. The results suggest that the resorption window of 6-12 weeks for the CaP coating seems to be confirmed at least in the human mandible, and that immediately loaded FBR-coated implants placed in the posterior mandible can achieve osseointegration within 6-12 weeks of loading.

Revascularised free flaps retain dual vascularisation, both periosteal and medullary, undoubtedly present optimal survival and minimal re-absorption in view of the prevalence of osteogenetic rather than osteoclastic phenomena. A revascularised free bone flap involves the transfer of a certain amount of bone tissue, whether or not associated with a muscular, skin and/or facial component, with the features of an axial flap, dissecting the vascular stalk of the donor site and re-anastomosing both the arterial and the venous components on to recipient vessels in the site of the primary defect. The vessels in question measure only about 2-4 mm, so that micro-surgery techniques must be applied. For bone defects less than 6 cm, with upkeep of the mandibular or maxillary cortical bone and preservation of the soft tissues, with residual bone of at least 8 mm in height and 4 mm in thickness, alveolar distraction may represent a valid alternative to bone grafts, at the same time as ensuring an increase of the alveolar bone and intraoral soft tissues involved in the distraction process.

High-resolution ultrasound (US) of the hand and wrist was compared with radiography in 26 young patients (mean age: 11.4 years) to be submitted to orthodontic therapy. US scans were targeted on the ossification centers critical for the growth spurt, namely the pisiform and adductor sesamoid bones of the metacarpophalangeal joint of the thumb and the cartilage of the distal phalanx of the third finger. All images were retrospectively reviewed on a double-blind basis by two independent observers who gave a conspicuity score to each structure of interest. All the scores were submitted to statistical analysis with the Wilcoxon test. US images clearly demonstrated the initial appearance of the ossification centers of the pisiform and sesamoid bones. These structures appeared as hyperechoic spots causing marked acoustic shadowing. The persistence of the phalangeal cartilage was depicted as a thin rim interrupting the hyperechoic cortical profile of the bone. US results were statistically equivalent to radiographic findings in the pisiform [p (op1) = .3105; p (op2) = .8886] and sesamoid bones of the thumb [p (op1) = .1386; p (op2) = .354]. A statistically significant difference between the two techniques was found in the third finger cartilage (p (op1) = .0277; p (op2) = .0759) because its profile was poorly depicted on some US images. To conclude, wrist US is proposed as a simple and valuable radiation-free support examination for the follow-up of skeletal maturation in adolescents to be submitted to orthodontic therapy.

The aim of this paper is to describe the development and growth of the middle-line cranial base synchondrosis and nasal septal cartilage of human fetuses. The sample consisted of 25 human fetuses aged from 9 weeks to 6 months. The samples were decalcified and processed in paraffin. Sections were cut at 10 mu and stained with Mallory staining. Histomorphological observation pointed out the presence and development of cranial base synchondrosis and nasal septal cartilage. As far as synchondrosis cell zone layers in endochondral growth sites are described moreover a caudorostral gradient in growth rate was observed. Functional connexions between the cartilaginous nasal capsule and the developing maxillae and premaxillae have been examined. The main connection was found to consist of the anterior septopremaxillary ligament running from the anterior border of the nasal septum posteroinferiorly to blend with premaxillary periosteum and interpremaxillary suture.

The authors report on the use of US in the evaluation of osteogenesis in the fractures treated with external fixation. From April 1991 to October 1992, fifty patients with diaphyseal fractures were submitted to real-time US examinations, with 7.5-5 MHz probes, mainly on longitudinal scans. The evolutive stage of bone callus was studied and, in the presence of periosteal bone bridge, its length and height were measured. In all but 4 patients US, unlike radiology, allowed the signs of osteogenesis to be detected as early as from day 10 on and the peculiar bilobate pattern known as primary callus response was clearly demonstrated. This stage is of fundamental importance because it allows, when periosteal callus is absent, direct intervention on the dynamic process, by varying the external fixation-bone complex so as to make it more flexible. In 80% of patients periosteal apposition was observed on day 24. Delayed osteogenesis depended on the patient's age and on fracture type. Such pathologic signs as hyperstimuli, pseudoarthrosis and/or hematoma persistence were quite unfrequent findings. Even though the study of US semiology is still in progress, our results are in substantial agreement with literature data and emphasize the role of US in the early evaluation of the bone callus and its evolution.

A study has been carried out on the dynamics of the osteogenesis induced in vitro by an intermittent mechanical load applied on intact metatarsals isolated from 12 day-old rats. The metatarsals, as soon as isolated, were deprived of both the ends and placed in culture medium (BGJb enriched with 10% FCS, 65 micrograms of ascorbic acid, penicillin, strepto) without a mechanical load. After 4-5 hours, half the bones were placed in our device, described in our previous paper (2), and submitted to a daily cycle of an intermittent mechanical load (11.6 g/mm2) 1/2 h long, at 1 Hz frequency. The remaining bones, used as control, were cultured in the same medium, without any mechanical load. 24, 48 and 72 hours from the first application of the load the bones were fixed, embedded (decalcified or undecalcified) and serially sectioned. The sections were stained with toluidin blu and trichromic Masson-Goldner. On the perimeter of 5 non-consecutive sections of each bone the number of the osteoblasts at 250x, and the nuclear volume of the same cells at 1000x were evaluated. In the culture media the alcaline phosphatase activity (p-nitrophenol as substrate) and the concentration of osteocalcin (RIA) were measured. The number and nuclear volume of the osteoblasts are higher in the loaded than in the control bones (tab. 1). The alcaline phosphatase activity does not vary in the control bones between 24 and 72 h, while it increases in the loaded bones. The concentration of the osteocalcin shows a slight increase at 48 h in the control bones, and a significant decrease int he loaded bones (fig. 1).(ABSTRACT TRUNCATED AT 250 WORDS)

The long-term results of 21 patients treated with modular screw cementless hip prostheses are reported. An examination of periprosthetic osteogenesis and function evaluated by gait analysis revealed good incorporation of the prosthesis and good clinical results in all of the cases studied.

Human teeth morphogenesis was studied by optical microscopy from the 10th to 20th week of fetal life. Enamel, dentin and pulp development were analyzed. An important observation on mandibu teeth arises from this investigation that consists in a biforcation of mandibular ossification in two branches, this could allow to the teeth to develop inside the mandibular arch.

The study of four cases of osteosis caused by primary hyperparathyroidism, tree female and one male, which have undergone surgery for pathological fractures in met-epiphysis bone, allows to analyze with the help of scanning electron microscope modifications occurring in periosteal and endosteal bone matrix. The periosteal surface appears abundantly furrowed by large and deep canals, irregularly joined together. Areas of resorption, these at rest and these of osteodeposition are distributed in changeable but regular way. The bone turnover of endosteal side is particularly accentuated. This surface contains the bone trabeculae residuals and is widely marked by deep Howship's lacunae, which show intense osteoclastic activity. It seem that osteocytes cells participate actively in the process of osteolysis, widening the lacunae and small canals which appear to be surrounded by calcospherites arranged in irregular way. Osteogenetic activity, with large areas of deposition, is very intense, as a defence attempt against osteolytic resorption process.

The authors conducted a histologic study on the modalities of ossification of the "diaphyseal osseous ferrule" in embryos between the sixth and eighth week of intrauterine life: the ossification of this "diaphyseal osseous ferrule" presents some peculiarities compared to that of other areas: it occurs with the modalities of periosteal ossification, exploiting, however, a cartilagenous substrate. In addition, the authors compared the ossification of the diaphyseal ferrule to that of the "perichondrial ferrule of the layer of ossification", examining histologic sections of embryos in the 25th week of intrauterine life.

A review of the physical properties of the magnetic fields is reported. Particular attention has been paid to the biological and clinical aspects of the electromagnetic fields applied to living structures of cells and bone tissue both susceptible to this exposition.

252 turkey eggs were put in an incubator at 39 degrees C and relative humidity 75%. From the 8th day of incubation up to the 28th, the authors opened 12 eggs a day, 6 at 8 a.m. and 6 at 8 p.m. The embryos were fixed by 10% buffered formaline for three days, dehydrated by alcohol 96% for seven days, eviscerated, coloured by alizarin S red and by alcian blue 8GX, then made diaphanans by means of KOH solutions. Then the authors have described the appearance times of the ossification nuclei in turkey, showing that in turkey the embryonal ossification occurs in a characteristic chronological order, different from that described in other birds, even if they belong to related species.

A 12-month old dog was sacrificed 4 months after fixation of the left anterior limb, in a cutaneous pouch, to the thoracic wall, and division of the ipsilateral brachial plexus; 27 and 7 days before sacrifice, Alizarin red (20 mg/Kg) was injected intravenously. Rarefaction of spongy bone and increase in the rate of osteogenic activity were recorded from the sections of the distal end of the unloaded left radius compared to the corresponding part of the control bone. The events mentioned appeared more marked in the "tubular" than in the "lamellar" spongiosa. These findings seem to offer new evidence supporting the suggestion that in adult life bone tissue reconstruction rate is relatively higher in the areas of spongy bone comparatively less involved in the mechanical resistance.

The main phases of ossification are shown-based on the results achieved by re-examining the X-ray pictures of 14 patients affected by tubular bones pseudoarthrosis treated with Ilizarov's closed compression-distraction osteosynthesis. The roentgen signs in particular are examined which are considered as expressive of positive evolution of the pseudoarthrosis. An outline of X-ray evolution of nonunions is also proposed, referring to the peculiar biological characters of ossification under compression-distraction stimulation.

Sinus pericranii is unusually demonstrated in the region of the obelion. The radiological findings are those of large parietal foramina and the overlying soft tissue is bulging, suggesting vascular collection. The possible relationship between ossification of parietal bone and vascular anomaly is discussed.

In a 14-month old dog, injected twice with Alizarian red 27 and 7 days before sacrifice, both the distribution of the osteogenic areas and the rate of new bone tissue formation have been studied in the distal metaphysis of the right radius submitted to mechanical overloading by removing a piece of the ulnar shaft. The normally loaded left radius was used as a control. Following a four-month overloading, the bone tissue deposition rate appeared markedly reduced in the more peripherally located "tubular" spongiosa which underwent in parallel conspicuous structural changes. No alterations in the reconstruction rate and in the microscopical structure as compared to the control radius were observed instead in the deep-seated "laminar" spongiosa. The present, as well as previous findings, seem to support the view that (1) the two types of trabecular bone, i.e. the "tubular" and the "laminar" spongiosa, are subjected to quantitatively diverse loading, and (2) mechanical factors play a significant role in the control of the topographic distribution of bone tissue reconstruction.