123 research outputs found
Ghost cells in compound odontoma: a study of undemineralized material
Calcifications and ghost cells at the enamel surface or in the ameloblastic epithelium were studied in twelve odontomas using undemineralized material.Calcified material formed focally in the intercellular portion of the enamel epithelium: this material showed a concentric layers arrangement.Ghost cells were present in most of the odontomas.These ghost cells were epithelial cells which enlarged, became eosiniphilic and underwent an aberrant type of keratinization with the formation of large masses of keratin, that didnât stain as deeply as normal keratin. These cells often showed karyolysis of the nucleus as keratinization progressed. Frequent was the appearance of dystrophic calcifications in individual cells or clusters of cells, characterized by extremely fine basophilic granularity. The outlines of these keratinized cells could often still be discerned, even if with some difficulty.Les calcifications et les cellules fantĂŽmes Ă la surface de lâĂ©mail ou dans lâĂ©pithĂ©lium amĂ©loblastique ont Ă©tĂ© Ă©tudiĂ©es dans 12 odontomes en utilisant du matĂ©riel non dĂ©caldfiĂ©.Le matĂ©riel calcifiĂ© est formĂ© focalement dans les portions intercellulaires de l'Ă©pithĂ©lium de l'Ă©mail: ce matĂ©riel montre un agencement en couches concentriques.Les cellules fantĂŽmes sont prĂ©sentes dans la plupart des odontomes. Ces cellules fantĂŽmes sont des cellules Ă©pithĂ©liales qui augmentent de taille, deviennent Ă©osinophiles et subissent un type aberrant de kĂ©ratinisation avec formation de larges masses de kĂ©ratine qui ne se colorent pas aussi intensĂ©ment que la kĂ©ratine normale. Ces cellules montrent souvent une karyolyse du noyau au fur et Ă mesure de la progression de la kĂ©ratinisation. Il Ă©tait frĂ©quent de rencontrer lâapparition de calcifications dystrophiques dans des cellules isolĂ©es ou en Ăźlots, caractĂ©risĂ©es par des granulations basophiles extrĂȘmement fines. Les contours de ces cellules kĂ©ratinisĂ©es peuvent ĂȘtre encore souvent discernĂ©s, quoique avec certaines difficultĂ©s
Light and Laser Scanning Microscopy analysis of hydroxyapatite used in periodontal osseous defects in man: evidence of a different resorption pattern in bone and soft tissues
Hydroxyapatite (HA) is a highly biocompatible material that recently has been shown to undergo biodegradation. The mechanisms of this phenomenon are unclear, and humoral and cellular events have been thought to be implicated. In the present study HA particles were put into infraosseous defects on teeth that were to be extracted for prosthetic reasons and then retrieved after a 1 year period. The specimens were processed with the cutting grinding system. Results show a very sharp difference of the biodegradation processes, related to the tissues that surround the HA particles. HA in tight contact with mineralized bone showed no evidence of degradation or resorption, while on the contrary, in the areas where bone loose connective tissue was present, it was possible to observe HA crystals detached and scattered in cells cytoplasm or extracellular fluids. This dissolution and resorption phenomenon were observed also by Laser Scanning Microscope (LSM) in fluorescent mode. These differences in degrees of degradation between bone and loose connective tissue could be due to the small amount of interstitial fluid present in mineralized bone and the greater flow of fluid through connective tissue.Lâhydroxyapatite (HA) est un matĂ©riel hautement biocompatible qui sâest rĂ©vĂ©lĂ© rĂ©cemment capable de subir une biodĂ©gradation. Le mĂ©canisme de ce phĂ©nomĂšne nâest pas clair, et semble impliquer une particination humorale et cellulaire. Notre recherche a portĂ© sur la mise en place de particules dâHA dans des dĂ©fects intraosseux en rapport avec des dents qui doivent ĂȘtre extraites pour des raisons prothĂ©siques, et sur leur etude suite Ă leur ablation un an aprĂšs. Les rĂ©sultats ont dĂ©montrĂ© des diffĂ©rences marquĂ©es dans le processus de dĂ©gradation en rapport avec les tissus qui entourent lâHA. Les particules dâHA qui sont en contact avec lâos minĂ©ralisĂ© ne prĂ©sentent pas de signes de dĂ©gradation ou de rĂ©sorption, tandis que dans les rĂ©gions oĂč du tissu conjonctif Ă©tait prĂ©sent, il est possible dâobserver des cristaux dâHA dĂ©tachĂ©s et dispersĂ©s dans le cytoplasme des cellules et dans le liquide extracellulaire. Ces phĂ©nomĂšnes de dissolution et de rĂ©sorption ont Ă©tĂ© Ă©galement Ă©tudiĂ©s au Microscope Electronique Ă Balayage au Laser en fluorescence. Ces diffĂ©rences dans le degrĂ© de dĂ©gradation observĂ©s dans lâos et dans le tissu conjonctif lĂąche pourraient ĂȘtre dues Ă la faible quantitĂ© de liquide interstitiel dans lâos minĂ©ralisĂ© et Ă la quantitĂ© plus grande de flux liquidien dans le tissu conjonctif
Repair of large sinus membrane perforations using stabilized collagen barrier membranes : surgical techniques with histologic and radiographic evidence of success
The most frequent intraoperative complication with sinus elevation is perforation of the schneiderian membrane. In most instances, the repair of this perforation is necessary to contain particulate grafting material and complete the procedure. New techniques are presented
here for the management of large perforations of the schneiderian membrane. A bioabsorbable collagen membrane is stabilized outside the antrostomy and then folded inward to create either a new superior wall that can obliterate a large perforation or a âpouchâ that can completely contain the particulate material. This can make it possible to complete a procedure
that otherwise may have had to be aborted by preventing dispersion of the particulate graft within the sinus cavity. Clinical cases are shown, along with follow-up at 6 to 9 months, demonstrating histologic and/or radiographic evidence of success, continued sinus health, and superior vital bone formation. The authors have used this technique on 20 consecutive patients without experiencing any procedural failures
Autologous tooth graft after endodontical treated used for socket preservation: A multicenter clinical study.
The aim of the study was to evaluate the tooth extracted use as autologous tooth graft after endodontic root canal therapies used for socket preservation. To this purpose, the Tooth Transformer shredding and decontamination machine has been used. The graft obtained in this way, was inserted at the time of the extraction or at a second surgery altogether with the chosen regenerative therapy. This clinical trial enrolled patients with post-estractive defects requiring the restoration bone dimension and shape in the maxillary and mandibular zone. In addition, 98 patients with 119 extraction sockets were enrolled across 10 standardized centers. An innovative preparation method, using the dedicated automated device Tooth Transformer, able to transform autologous teeth in suitable grafting material, has been used. The extracted tooth was cleaned and treated using a Tooth Transformer and made a socket preservation. Thirteen Biopsies were realized to analyze the histologic outcomes at the average time of four months to demonstrate that the autologous tooth graft made from root after endodontic therapy should be used in human bone regeneration as graft for dental implant placement
Influence of menopause on mandibular bone quantity and quality in Japanese women receiving dental implants
Improved Methods for Acrylic-Free Implants in Non-Human Primates for Neuroscience Research
Traditionally, head fixation devices and recording cylinders have been implanted in nonhuman primates (NHP) using dental acrylic despite several shortcomings associated with acrylic. The use of more biocompatible materials such as titanium and PEEK is becoming more prevalent in NHP research. We describe a cost effective set of procedures that maximizes the integration of headposts and recording cylinders with the animalâs tissues while reducing surgery time. Nine rhesus monkeys were implanted with titanium headposts, and one of these was also implanted with a recording chamber. In each case, a three-dimensional printed replica of the skull was created based on computerized tomography scans. The titanium feet of the headposts were shaped, and the skull thickness was measured preoperatively, reducing surgery time by up to 70%. The recording cylinder was manufactured to conform tightly to the skull, which was fastened to the skull with four screws and remained watertight for 8.5 mo. We quantified the amount of regression of the skin edge at the headpost. We found a large degree of variability in the timing and extent of skin regression that could not be explained by any single recorded factor. However, there was not a single case of bone exposure; although skin retracted from the titanium, skin also remained adhered to the skull adjacent to those regions. The headposts remained fully functional and free of complications for the experimental life of each animal, several of which are still participating in experiments more than 4 yr after implant
The Bone-Forming Effects of HIF-1α-Transduced BMSCs Promote Osseointegration with Dental Implant in Canine Mandible
The presence of insufficient bone volume remains a major clinical problem for dental implant placement to restore the oral function. Gene-transduced stem cells provide a promising approach for inducing bone regeneration and enhancing osseointegration in dental implants with tissue engineering technology. Our previous studies have demonstrated that the hypoxia-inducible factor-1α (HIF-1α) promotes osteogenesis in rat bone mesenchymal stem cells (BMSCs). In this study, the function of HIF-1α was validated for the first time in a preclinical large animal canine model in term of its ability to promote new bone formation in defects around implants as well as the osseointegration between tissue-engineered bone and dental implants. A lentiviral vector was constructed with the constitutively active form of HIF-1α (cHIF). The ectopic bone formation was evaluated in nude mice. The therapeutic potential of HIF-1α-overexpressing canine BMSCs in bone repair was evaluated in mesi-implant defects of immediate post-extraction implants in the canine mandible. HIF-1α mediated canine BMSCs significantly promoted new bone formation both subcutaneously and in mesi-implant defects, including increased bone volume, bone mineral density, trabecular thickness, and trabecular bone volume fraction. Furthermore, osseointegration was significantly enhanced by HIF-1α-overexpressing canine BMSCs. This study provides an important experimental evidence in a preclinical large animal model concerning to the potential applications of HIF-1α in promoting new bone formation as well as the osseointegration of immediate implantation for oral function restoration
Influence of bone density on implant stability parameters and implant success: a retrospective clinical study
<p>Abstract</p> <p>Background</p> <p>The aim of the present clinical study was to determine the local bone density in dental implant recipient sites using computerized tomography (CT) and to investigate the influence of local bone density on implant stability parameters and implant success.</p> <p>Methods</p> <p>A total of 300 implants were placed in 111 patients between 2003 and 2005. The bone density in each implant recipient site was determined using CT. Insertion torque and resonance frequency analysis were used as implant stability parameters. The peak insertion torque values were recorded with OsseoCare machine. The resonance frequency analysis measurements were performed with Osstell instrument immediately after implant placement, 6, and 12 months later.</p> <p>Results</p> <p>Of 300 implants placed, 20 were lost, meaning a survival rate of %. 93.3 after three years (average 3.7 ± 0.7 years). The mean bone density, insertion torque and RFA recordings of all 300 implants were 620 ± 251 HU, 36.1 ± 8 Ncm, and 65.7 ± 9 ISQ at implant placement respectively; which indicated statistically significant correlations between bone density and insertion torque values (p < 0.001), bone density and ISQ values (p < 0.001), and insertion torque and ISQ values (p < 0.001). The mean bone density, insertion torque and RFA values were 645 ± 240 HU, 37.2 ± 7 Ncm, and 67.1 ± 7 ISQ for 280 successful implants at implant placement, while corresponding values were 267 ± 47 HU, 21.8 ± 4 Ncm, and 46.5 ± 4 ISQ for 20 failed implants; which indicated statistically significant differences for each parameter (p < 0.001).</p> <p>Conclusion</p> <p>CT is a useful tool to determine the bone density in the implant recipient sites, and the local bone density has a prevailing influence on primary implant stability, which is an important determinant for implant success.</p
A new biphasic osteoinductive calcium composite material with a negative Zeta potential for bone augmentation
The aim of the present study was to analyze the osteogenic potential of a biphasic calcium composite material (BCC) with a negative surface charge for maxillary sinus floor augmentation. In a 61 year old patient, the BCC material was used in a bilateral sinus floor augmentation procedure. Six months postoperative, a bone sample was taken from the augmented regions before two titanium implants were inserted at each side. We analyzed bone neoformation by histology, bone density by computed tomography, and measured the activity of voltage-activated calcium currents of osteoblasts and surface charge effects. Control orthopantomograms were carried out five months after implant insertion. The BCC was biocompatible and replaced by new mineralized bone after being resorbed completely. The material demonstrated a negative surface charge (negative Zeta potential) which was found to be favorable for bone regeneration and osseointegration of dental implants
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