A rodent model was developed to assess the osteogenic potential of continuous capacitive electrical stimulation on bone healing around titanium (Ti) implants. Adult male rats were fitted subcutaneously with electrical leads, that were placed around Ti implants inserted in the tibia. One electrical lead was attached directly to the extraosseous component of the implant, and the other was anchored to the adjacent subcutaneous tissues. Bone healing around the Ti implant was assessed histologically after 2, 3, 4, 5, 6, 7, 14 and 21 days of continuous capacitive electrical stimulation as compared to controls and sacrificed immediately. Other groups of animals were given 7 days of continuous capacitive electrical stimulation but sacrificed at day 14 or 21 post-implantation. Histomorphometric analysis of the bone-Ti interface revealed that animals given 5--7 days of continuous capacitive electrical stimulation demonstrated more bone at the surface of the Ti implant than in controls. Radioautographic analyses of bone formation was carried out in rats injected with tritiated (3H)-proline 4 days prior to sacrifice at days 7, 14 and 21. These results showed increased 3H-proline deposition at day 7, corresponding to increased bone formation as shown by morphometric findings. Biomechanical 'pull-out' tests demonstrated that the force required to remove the Ti implants from the tibiae was significantly greater in electrically stimulated animals compared to controls at day 7. Bone densitometric measurements revealed a statistically significant increase in bone density in the electrically-stimulated animals by days 5--7 compared to controls. In summary, an animal model was developed to evaluate the effects of continuous capacitive electrical stimulation on bone healing around Ti implants placed in tibiae of rats. Significant bone growth was demonstrated by days 5--7 postimplantation as in all parameters tested. These findings suggest that continuous capacitive electrical stimula

Since 1983, the WHO has recommended the use of the INR for measuring the level of anticoagulation for patients receiving warfarin therapy. However, no scientifically-derived guidelines, using the INR, for the surgical management of this group of patients exists. In the first part of this study, the protocols followed by oral surgeons, when treating patients receiving warfarin, and who require dental extractions were established by performing a mail survey. The results of the survey illustrated that although the majority of oral surgeons use the INR, most of them use the INR along with the PT and only one fifth of them use this measure alone. In the second part of this study, dental extractions were performed on rabbits which were anticoagulated to various INR levels. The results of this study strongly suggest that dental extractions may be safely performed on subjects receiving oral anticoagulants using routine measures for local hemostasis.

Introduction: Manufactured Colas are consumed universally as soft drinks. Evidence about the acid contents of Cola-beverages and its effects on teeth is rare. Aim: To assess: (i) cola acidity and buffering capacity in vitro, (ii) tooth erosion after swishing with colas in vivo (iii) scanning electron microscopic effects on teeth of colas, and tooth-brush abrasion, and (iv) report a clinical case of erosion from cola consumption. Materials and Methods: (i) We measured six commercially available pop ‘Cola-beverages', pH and buffering capacities using a pH-Mettler Automatic Titrator, with weak solution of Sodium Hydroxide. (ii) Two cohorts, one with teeth, the second without teeth rinsed with aliquots of Cola for 60 seconds. Swished cola samples tested for calcium and phosphorus contents using standardized chemical analytical methods. (iii) Enamel, dentine and the enamel-cemental junction from unerupted extracted wisdom teeth were examined with a scanning electron microscope after exposure to colas, and tested for tooth-brush abrasion and (iv) a clinical case of pop-cola erosion presentation, are all described. Results: Comparisons among pop-colas tested in vitro reveal high acidity with very low pH. Buffering capacities in milliliters of 0.5M NaOH needed to increase one pH unit, to pH 5.5 and pH 7 are reported. Rinsing in vivo with pop-cola causes leaching of calcium from teeth; SEM shows dental erosion, and pop-cola consumption induces advanced dental erosion and facilitates abrasion. Conclusions: (i) Pop-Cola acid activity is below the critical pH 5.5 for tooth dissolution, with high buffering capacities countering neutralization effects of saliva; (ii) calcium is leached out of teeth after rinsing with pop-colas; (iii) SEM evidence explains why chronic exposure to acid pop-colas causes dental damages; and (iv) a clinical case of pop-cola erosion confirms this. Key Words: Acid, Attrition, Abrasion, Beverages, Buffering, Calcium, Cola, Coca-Cola, Diet-Coke, Diet-Pepsi, Diet-Selection, Erosion, Frangibles, Pepsi, Selection-Cola, Teeth. / Introduction : Il se consomme des boissons gazeuses de type cola partout dans le monde. Les éléments de preuve concernant la teneur en acide des boissons de type cola et ses effets sur les dents sont rares. Objectif : (i) Mesurer l'acidité et le pouvoir tampon du cola in vitro, (ii) mesurer l'érosion dentaire à la suite d'un rinçage in vivo avec des colas, (iii) mesurer les effets du cola sur les dents au moyen d'un microscope électronique à balayage, ainsi que l'abrasion découlant du brossage, et (iv) présenter un cas clinique d'érosion issue de la consommation de cola. Matériel et méthodes : (i) Nous avons mesuré le pH et les pouvoirs tampons de six boissons gazeuses commerciales de type cola au moyen d'un pH-mètre et d'un titrimètre automatique de Mettler, avec une solution faible d'hydroxyde de sodium. (ii) Deux groupes, l'un dont les membres avaient des dents et l'autre non, se sont soumis à un rinçage de 60 secondes avec une aliquote de cola. La teneur en calcium et en phosphore des échantillons se rapportant au rinçage avec du cola a été mesurée au moyen de méthodes normalisées de chimie analytique. (iii) L'émail, la dentine et la jonction émail-cément des troisièmes molaires extraites n'ayant pas fait leur éruption ont été examinés au microscope électronique à balayage après l'exposition au cola, et ont été soumis à un test d'abrasion par brosse à dents, et (iv) un cas clinique d'érosion attribuable au cola est présenté. Résultats : Les comparaisons entre les colas testés in vitro révèlent une acidité élevée avec un pH très bas. Les pouvoirs tampons en millilitres de NaOH 0.5 M devaient augmenter d'une unité de pH, et les mesures de pH 5.5 et pH 7 sont rapportées. Le rinçage in vivo avec du cola entraîne la décalcification des dents. En effet, les examens réalisés au microscope électronique à balayage montrent une érosion dentaire. Par conséquent, la consommation de colas provoque une érosion dentaire avancée et contribue à l'abrasion. Conclusions : (i) L'activité acidifiante du cola se situe sous le seuil critique de pH 5.5 pour la dissolution dentaire, et présente un pouvoir tampon élevé qui annule les effets neutralisants de la salive; (ii) le calcium est éliminé des dents après le rinçage avec les colas; (iii) les analyses réalisées au microscope électronique à balayage expliquent pourquoi l'exposition chronique à l'acidité des colas entraîne une fragilité dentaire ; et (iv) un cas clinique d'érosion due au cola vient confirmer les résultats obtenus. Mots clés : Acide, Attrition, Abrasion, Boissons, Tamponnage, Calcium, Cola, Coca-Cola, Coke diète, Pepsi diète, Sélection diète, Érosion, Fragile, Pepsi, Sélection cola, Dents.

Objectives. This study was undertaken to evaluate whether the effects of hyperbaric oxygen (HBO) therapy could alter the critical size for spontaneous healing of a bone defect in the rabbit calvarial model. / Study design. An animal trial of 12 weeks duration was conducted using 20 New Zealand White rabbits, which were randomly divided into 2 groups of 10 animals each. Calvarial defects were created in the parietal bone of each animal bilaterally. Defects were critical sized, 15mm on one side and supra critical sized, 18mm on the contralateral side. Group 1 received 90 minutes HBO treatment sessions at 2.4 ATA per day for 20 consecutive days. Group 2 served as a control without any HBO treatment sessions. Five animals in each group were sacrificed at 6 and 12 weeks. Data analysis included qualitative assessment of the calvarial specimens, post sacrifice radiographs as well as histomorphometric analysis to compute the amount of regenerated bone within the defects. Two way ANOVA was used for statistical analysis. / Results. Both radiographic analysis and histomorphometric analysis demonstrated that HBO treated animals had significantly more new bone within defects compared with the control group. There was no statistically significant difference between the percentage of new bone forming in the 15mm and 18mm HBO treated defects. There was no difference between the 6 week and the 12 week HBO treated groups. / Conclusion. HBO is effective in enhancing the bone healing of full thickness critical sized as well as supra-critical sized defects in the rabbit calvarial model. Bone regeneration was significantly greater in the HBO treated animals regardless the defect size. HBO may have increased the diameter of the rabbit critical sized calvarial defect to more than 18mm.

INTRODUCTION: Deciduous and permanent teeth differ in shape and calcium content. Deciduous enamel and dentin are thinner and softer than permanent teeth. Chronic, frequent imbibing of acidulated pop-drinks imbibing is erosive, and dentinal pain occurs after rinsing with acidulated pop-drinks. Since calcium and phosphorous leach from teeth with acid drinks, we investigated pop-colas and pop-guaraná for pain sensitivity and erosion in adults and children. AIM: This research assessed (i) in vitro, the pH buffering, calcium, phosphorous and fluoride content of pop-guaraná and pop-colas. This research compares (ii) in situ scanning surface electron microscopy (ESEM) of granular hydroxyapatite crystals (HAP), enamel, dentin and enamel-dentin junctions (AMCJx) after exposure to pop-colas and pop-guaraná. This research reports (iii) in vivo calcium and phosphorous, leached from children and adults derived from erosion after swishing with pop-colas and pop-guaraná. This research assesses (iv) in vivo pain in children and adults after swishing with pop-colas and pop-guaraná. METHODS: Six pop-colas (3 regular; 3 diet) and six pop-guaraná drinks (4 regular; 2 diet) were tested pH, buffering capacity, calcium, phosphorus and fluoride concentrations using standard chemical analytical methods: ICP-OES for calcium and phosphorous, and a Single Orion Electrode for fluoride, coupled to an automated electronic digital recorder. Scanning surface electron microscopy (ESEM), without metal coating, was used to examine calcified samples. The same precise microscopic locations were used for visual comparisons. Three cohort volunteers (adult dentate, adult edentulous and children dentate) swished aliquots of drinks for 30s. Each drink had readings recorded 72 times. Six colas and six guaraná drinks from source and mouth rinse were tested for calcium and phosphorous. VAS scales were used for comparisons of pain for each drink. RESULTS: Data showed significant (p < .0001) increases of calcium and phosphorous after rinsing with colas and significantly less (p < .0001) leaching after rinsing with guaraná. Guaraná induced less pain than colas. Children show more erosion with rinsing colas than guaraná, but less pain after cola rinsing than adults. Little pain with guaraná rinses was recorded in children. All guaraná pop-drinks have fluoride content, with a range from concentration at 0.8 ppm F- to 1.6ppm F. CONCLUSION: While both colas and guaraná are erosive to teeth and cause pain in adults and children, pop-colas are more erosive than guaraná in children, and colas induce more dentinal pain in adults than in children. Fluoride in the drink may modulate the erosion. ESEM evidence shows guaraná pop drinks demonstrate marked visual increases in mordant changes of HAP and the hard tissues of teeth. Some pop-guaraná drinks are less erosive than others are. KEYWORDS: Acid, attrition, abrasion, beverages, buffering, calcium, phosphorus, guaraná, erosion, teeth. / RésuméINTRODUCTION : Les dents décidues et les dents permanentes diffèrent par leur forme et teneur en calcium. L'émail et la dentine de dents décidues sont plus minces et moins dure que les dents permanentes. Si utilisée de façon chronique, souvent l'ingestion de boissons gazeuses acidulées est érosive, et la douleur dentinaire se produit après rinçage à boisson gazeuse acidulée. Étant donné la perte de calcium et de phosphore découlant de L'ingestion des boissons acides, nous avons étudié des boissons gazeuses colas et guaraná pour La sensibilité à la douleur et l'érosion. OBJECTIF: Cette recherche a évaluée: (i) in vitro le pH, le pouvoir tampon, le calcium, le phosphore et la quantité de fluorure des boissons gazeuses guaraná et colas, (ii) la comparaison des données in situ: - Surface de microscopie électronique à balayage: cristaux d'hydrox apatite granulaire, émail, dentine, l'émail -dentine jonction (AMCJx) (iii) in vivo la perte de calcium et de phosphore chez enfants et chez adultes pour l'érosion avec des boissons gazeuses colas et de guaraná, et (iv) la douleur après le rinçage. MÉTHODES: Six boissons gazeuses colas (3 régulières; 3 diètes) et six boissons gazeuses guaraná (4 régulières, 2 diètes), ont été testées le pH, le pouvoir tampon, le calcium, phosphures et le fluorure ont été mesurées dans le guaranás. En utilisant des méthodes chimiques classiques d'analyse; ICP-OES pour le calcium et le phosphore et un unique Orion électrode pour le fluorure, couplé à un enregistreur numérique automatisé électronique. Trois cohortes de bénévoles, (la première des adultes dentées, la deuxième des adultes édentés, et la troisième des enfants dentées); rinçage des aliquotes de boissons pendant 30s. Chaque échantillon a été analysé, des mesures ainsi que des moyennes ont été enregistrées (α ÷ 6 = β où α a été la lecture et β la moyenne); 12 échantillons de chaque boisson ont été enregistrés (β X 12 mesures pour toutes les boissons) pour chaque boisson appréciée. En conséquence, chaque boisson a eue des lectures enregistrées pour un total de 72 fois, toutes avec des méthodes standards préétablies. Colas de la source et pos rinçage ont été testés pour le calcium et le phosphore. Des échelles EVA ont été utilisées pour les comparaisons de la douleur, (notes initiales et pos rinçage pour chaque boisson). Chaque analyse a été vérifiée comme décrite pour les six guaraná évaluées. RÉSULTAT: Les données ont montré une augmentation significative du calcium et du phosphore après rinçage avec les colas et beaucoup moins après rinçage avec le guaraná. Le Guaraná cause moins de douleur que les colas. Les enfants montrent une plus grande érosion lors du rinçage avec l'utilisation de cola par rapport le guaraná, mais moins de douleur. Cependant les enfants accusent moins de douleur après rinçage avec cola que les adultes. Chez les enfants, le rinçage avec le guaranás a produit peu de douleur. Toutes les boissons gazeuses à base de guaraná ont une quantité en fluorure. La boisson gazeuse Kuat montrant la plus faible concentration à 0,8ppm F- tandis que l'Antarctica et la régulière Mineiro sont a plus de 1,6ppm F-. CONCLUSION: Bien que les deux colas et le guaraná sont érosifs sur les dents et causent de la douleur chez les adultes et chez les enfants, les boissons gazeuses colas sont plus érosives que le guaraná chez les enfants, et les colas provoquent plus des douleurs dentinaires chez les adultes que chez les enfants. Le fluorure dans la boisson peut moduler l'érosion. La preuve ESEM démontre que les boissons gazeuses au guaranás. Dénotent une augmentation marquée de changements visuels concernant le occlusal/bord incisif de HAP et de tissus durs des dents. Guaraná Mineiro cause moins de dommages par rapport à toutes les boissons gazeuses guaraná testées. MOTS-CLÉS: acides, de l'attrition, l'abrasion, des boissons, le pouvoir tampon, le calcium, le phosphore, le guaranás. , l'érosion, dents.

The use of endosseous titanium implants, for the replacement of missing teeth, has become a predictable treatment alternative in restorative dentistry. Success of dental implants appears to be related to the quality of bone. Bone of high quality will ensure better implant stability and, consequently, better conditions for osseointegration. This thesis reviews both and human data related to bone quality in association with endosseous titanium implant placement. / Biomechanical pull out testing is one among several methods used to quantitatively assess the forces required to remove an implant from bone. Pull out testing has the advantage of assessing the biomechanical stress between two materials of different physical and chemical properties, in this case bone and a titanium, implant surface. The variability of our results in the animal model led us to review our laboratory notes. Interesting correlations between the initial implant stability and the eventual pull out values were identified. Clinical data involving many variables were available from previous clinical trials and an attempt was made to retrospectively evaluate this information. The goal of this process was to determine, clinically, if a similar correlation could be identified between initial impressions at the time of implant placement and ultimate implant success. / Clinical data revealed that the following variables were important for the final prognosis of an implant: dental arch, implant length, method of insertion, bone graft, the surgeon, jaw bone quality and jaw bone quantity. Using a sophisticated statistical analysis, generalized estimating equation, most of these factors were found only to indirectly influence the success or failure of an implant. Our clinical findings suggested that jaw bone quality and quantity were the primary determining factors for implant success. This supports our observations from the animal study.

Bone is constantly undergoing remodeling of its bony matrix in response to various stimuli impinged upon the tissue. Bony remodeling occurs in both the dentate and edentulous states, but the edentulous lose more bone over time. This study analyzed sex, age and years edentulous for their influence on the height, width and shape of the anterior residual alveolar ridge of the jaws. Significantly greater amounts of mandibular residual alveolar bone height were found in males (p < 0.0001) and in those with more edentulous years in the maxilla (p = 0.003). The maxilla showed significantly greater amounts of residual alveolar bone height in the group with fewer edentulous years (p = 0.004). No significant associations were detected when sex, age and years edentulous were compared with anterior maxillary bone width. Statistical analysis of this study population also revealed no significant associations between sex, age, and years edentulous and anterior maxillary bone shape.

<p> Objectives: The oral cavity may be an important and overlooked reservoir of systemic infection, and athletic appliances may constitute a potentially important and under-recognized risk factor for infection. </p><p> Athletic mouthguards are difficult to clean and provide retentive sites for microorganisms. These microrganisms are organized as biofilms and can adhere to the acrylic, which has porosities on its outer and inner surfaces that create favorable conditions for bacterial colonization. Athletic appliances are not disinfected routinely at home and there is no specific clinical protocol for the control of bacterial biofilm on these appliances. Although adequate brushing or scrubbing with a dentrifice is an effective means of controlling the biofilm, inappropriate home-care quality and frequency are factors that compromise the efficacy of the mechanical control of biofilm. In addition, many athletic mouthguards are often left in the locker-room, and while in use at the athletic site, are often transferred from the mouth to hands, and temporarily stored or carried at distant sites (eg helmuts, shorts, sleeves, socks etc). </p><p> The two most frequently gram-positive cocci isolated from athletic mouthguards were <i>Staphylocccus aureus</i> and <i>Staphylococcus epidermidis, </i> prominent skin pathogens that are also associated with endocarditis, pericarditis, pneumonia, osteomyelitis, food intoxication, and athletic equipment contamination. Methicillin-resistant <i>S. aureus</i> is an important nosocomial pathogen, which is often transmitted from the colonized site to the site of subsequent infection, and is responsible for considerable morbidity and mortality. Athletic mouthguards may be a reservoir for these bacteria to hibernate and thus be a mechanism of transmittal from one site to another. An increase in community associated MRSA (aka close-quarter MRSA) outbreaks has been noted in basketball, football, rugby, volleyball, and wrestling athletes. and some strains of S. aureus are the most common cause of cultured skin abscesses in athletes. </p><p> Good personal hygiene is the key to prevention and control of community associated MRSA outbreaks. Such practices among athletes include frequent hand washing, covering abrasions or seeping wounds, disallowing athletes with open wounds in whirlpools or saunas, discouraging shared personal items, requiring showers after all practices and games, wearing sandals in showers, isolating athletes who have infections, and washing protective gear after each use. Recommended infection control measures include regular and thorough cleaning of equipment, however when antimicrobial treatment is recommended, specific products are not identified. Therefore , the purpose of this study was to assess alternative methods of disinfecting samples of acrylic from surface and subsurface inoculates of specific bacteria, having in mind methods that maybe used at the athletic site and in the locker-room. </p><p> <i>Methods:</i> In this study, we tested the efficacy of the Nature/Zone&trade; ozone sanitizing chamber and Purell&trade; hand sanitiazer in disinfecting surfaces of acrylic specimens prepared from mouthguards. <i> Staphylococcus epidermidis</i> (aka <i>S. aureus</i>), <i> Lactobacillus casei,</i> and <i>Escherichia coli</i> were purchased from the American Type Culture Collection, Manasas, Va. All experiments were conducted in a laminar flow hood and all equipment was autoclaved prior to use. Growing cells were placed on the surface of sterile acrylic discs and then either Purell was added to the disc for three iv minutes, or the inoculated discs were subjected to ozone in the chamber for three minutes. Alternatively, growing cells were placed in Eppendorf tubes to simulate porosities in the acrylic. All specimens (discs or inoculates) were then transferred to 10 ml of culture broth, grown overnight, and compared to positive and negative controls. After overnight incubation, each working solution was diluted in ten-fold steps for the purpose of estimating bacterial cell numbers. From the dilutions , 0.1 ml was spread evenly across the surface of their respective agars. All agar plates were incubated for 24 hrs. at 37 C, after which all visible colonies were counted. The number of colony forming units (CFU) were determined by counting segments of the plates. All experiments were performed in triplicate, and experimental samples were compared to positive and negative controls. One way analysis of variance was used to compare colony counts between positive control samples , experimental ozone chamber samples, and experimental Purell&trade; samples. </p><p> <i>Results:</i> Three trials indicated that there was no inhibition of growth of the organisms when sterile discs or eppendorf tubes were incubated in the ozone chamber for 3 minutes. As compared to positive control and the ozone chamber experimental samples, surface application of hand sanitizer (Purell&trade;) for 3 minutes significantly inhibited growth of all three bacteria (p = 0.05, one way ANOVA). </p><p> <i>Conclusions:</i> These findings indicate that ozone produced by the Nature/Zone UV sanitizer is ineffective in reducing bacterial counts of the three organisms used in these in vitro experiments. On the other hand, Purell hand sanitizer, significantly reduced the number of bacterial counts of all three organisms. Thus, whereas the hand sanitizer is an effective disinfectant, the ozone chamber is not an effective disinfectant.</p>

Many dental devices combine acrylic (i.e. poly-methyl methacrylate or bisphenol A-glycidyl methacrylate) and metallic parts (i.e. titanium or stainless steel) that are bonded together. These devices often present catastrophic mechanical failures due to weak bonding between their acrylic and metallic components. These devices include dental prostheses, combining metallic frameworks (i.e. titanium) and wrought wires with acrylic resin; and orthodontic appliances, combining acrylic resin with stainless steel wrought wires or composite with stainless steel brackets. The bonding between metals and polymers in dental devices is usually performed by the mechanical interlocking, but its bond strength is still too low for dental applications. The bond strength between them would be high if the chemical bonding, which does not occur spontaneously, uses in addition to the mechanical interlock. The objective of this study was to develop a new method of creating a strong chemical bond between alloys and polymers for dental devices based on diazonium chemistry.The chemical bond between metals (i.e. titanium or stainless steel) and polymers (i.e. poly-methyl methacrylate, PMMA or Bisphenol A-glycidyl methacrylate, Bis-GMA) was achieved in two steps. In the first reaction step (primer), the aryldiazonium salts were chemically reduced to form aryl radicals which spontaneously got grafted onto the metallic surfaces. The second step of the reaction (adhesive) was optimized to achieve covalent binding between the grafted layer and PMMA or Bis-GMA. The chemical composition of the treated surfaces was analyzed with X-ray photoelectron spectroscopy (XPS), and the bonding strengths between alloys and PMMA or Bis-GMA were measured. XPS characterization and contact angle measurement confirmed the presence of a polymer coat on the treated metallic surfaces. Whereas, the mechanical test results showed a significant increase of the tensile bond strength between PMMA and treated titanium or stainless steel wire by 5.2 and 2.5 folds, respectively, compared to the untreated control group (P<0.05). Moreover, the bonding strength between metallic brackets and Bis-GMA composite was increased after the treatment depending on the bracket design by 2 to 3.9 folds compared to untreated brackets. Diazonium chemistry provides an effective way of achieving a strong chemical bond between alloys and PMMA or Bis-GMA. The resulting bonding method can be utilized to further improve the properties of dental devices, reduce debonding of dental prostheses and brackets, provide more leverage in orthodontic cases with complex mechanics, and allow the use of brackets with smaller bases. / De nombreux appareils dentaires sont composés d'acrylique (c'est à dire d'un poly -méthacrylate de méthyle ou de bisphénol A- glycidyle méthacrylate) et de parties métalliques (par exemple en titane ou en acier inoxydable) qui sont collés ensemble. Ces dispositifs présentent souvent des défaillances mécaniques catastrophiques en raison de la faiblesse de la liaison entre les composantes en acrylique et celles en métal. Ces dispositifs comprennent les prothèses dentaires, alliant des cadres métalliques (c'est à dire de titane) et fils forgé avec de la résine acrylique, et les appareils orthodontiques, combinant de la résine acrylique avec des fils forgé en acier inoxydable ou un composite avec des supports en acier inoxydable. La force de liaison entre eux serait élevée si la liaison chimique, ce qui ne se produit pas spontanément, est utiliser en plus du verrouillage mécanique. Dans la première étape de la réaction, les sels d'aryl diazonium sont réduits chimiquement pour former des radicaux aryles qui sont spontanément greffés sur les surfaces métalliques La deuxième étape de la réaction a été optimisée pour réaliser la liaison entre la couche greffée et le PMMA ou le Bis-GMA. La caractérisation XPS et la mesure de l'angle de contact a confirmé la présence d'une couche de polymère sur les surfaces métalliques traitées. Les résultats des essais mécaniques ont montré une augmentation significative de la force d'adhérence à la traction entre le PMMA et le titane traité ou d'un fil en acier inoxydable de 5,2 et 2,5 plis, respectivement, par rapport au groupe témoin non traité (p < 0,05). La chimie de diazonium fournit un moyen efficace d'atteindre une liaison chimique forte entre les alliages et le PMMA ou le Bis-GMA. Le procédé de collage qui en résulte peut être utilisé pour améliorer les propriétés des appareils dentaires, réduire le décollement de prothèses dentaires et des supports, et permettre l'utilisation de supports avec des bases plus petites.

Sphingomyelin phosphodiesterase 3 (SMPD3), a plasma membrane-bound enzyme, cleaves sphingomyelin to generate ceramide and phosphorylcholine. These two bioactive lipid metabolites regulate many cellular activities. A recessive mutation called fragilitas ossium (fro) in the Smpd3 gene leads to impaired bone and tooth mineralization in the fro/fro mice. Most fro/fro mice do not survive beyond the perinatal period that makes it difficult to get enough number of mice for the phenotypic analyses. Our specific aims are: 1) Generate viable fro/fro mice on a C57BL/6-C3H/HeN mixed background to analyze their tooth mineralization defects; and 2) Generate viable fro/fro mice on a pure C57BL/6 background by transient expression of Smpd3 during late embryonic development, and characterize their skeletal phenotype. We observed an improved survival of the fro/fro mutants on the C57BL/6-C3H/HeN mixed background. Examination of the teeth of these mixed background-mutants revealed a delayed mantle dentin mineralization and consequently, a delay in enamel mineralization. These tooth abnormalities progressively improved with time. The restoration of Smpd3 expression driven by a Col1a1-Smpd3 transgene in the odontoblasts corrected the tooth mineralization defects in fro/fro;Col1a1-Smpd3 mice. In order to obtain viable fro/fro mice on the C57BL/6 background, we followed a strategy based on the Tet-On inducible gene expression system. Following a complex breeding strategy, we generated fro/fro;ROSA-rtTA;TRE-Smpd3 compound mutant mice. The ubiquitous ROSA promoter drives the expression of rtTA transactivator in these mice. When treated with doxycycline, TRE-Smpd3 expression was induced in the cells synthesizing the rtTA protein in the compound mutants. The doxycycline treatment given to the pregnant mothers during the late gestation period resulted in the correction of the limb deformities and the skeletal mineralization defects in fro/fro;ROSA-rtTA;TRE-Smpd3 embryos. However, induction of Smpd3 expression in the adolescent fro/fro;ROSA-rtTA;TRE-Smpd3 mice was not sufficient to correct the defects in trabecular bone mineralization and the impaired growth of the long bones. This novel mouse model will be a useful tool to study SMPD3 biology in vivo. / La sphingomyéline phosphodiestérase 3 (Smpd3) code pour enzyme liée à la membrane plasmique qui clive la sphingomyéline et génère du céramide et de la phosphorylcholine. Ces métabolites lipidiques bioactifs jouent un rôle important dans de nombreuses activités cellulaires. Une mutation autosomique récessive du gène smpd3 est à l'origine du modèle murin fragilitas ossium (fro). Cette mutation est associée à une altération de la minéralisation des os et de la matrice extracellulaire des dents chez les souris fro/fro. De plus, ces souris sont de plus petites tailles et ont un taux élevé de mortalité périnatale, ce qui rend difficile l'obtention d'un nombre suffisant de souris pour l'analyse phénotypique. Nos objectifs étaient de 1) augmenter le taux de survie des fro/fro souris et de caractériser les défauts de minéralisation des dents, et 2) générer un modèle fro/fro sur un fond génétique pur C57BL/6 par l'expression transitoire de Smpd3 au cours du développement embryonnaire tardif. Normalement, aucune fro/fro souris sur le fond C57BL/6 ne survit au-delà de la période périnatale. Cependant, nous avons observé une meilleure survie des fro/fro mutants sur le fond mixte C57BL/6-C3H/HeN. De plus, L'examen des dents de ces derniers a révélé un retard dans la minéralisation du manteau dentinaire et, par conséquent, un retard dans la minéralisation de l'émail. Mais, ces anomalies dentaires se sont progressivement améliorées avec le temps. Par contre, la restauration de l'expression de Smpd3 contrôlée par le transgène Col1a1-Smpd3 dans les odontoblastes a corrigé les défauts de minéralisation des dents des souris fro/fro;Col1a1-Smpd3. Afin d'obtenir des souris viables fro/fro sur le fond C57BL/6, nous avons suivi une stratégie basée sur le système d'expression génique inductible Tet-On et sur une méthode complexe de sélection pour générer des souris fro/fro;ROSA-rtTA;TRE-Smpd3 double mutants. Dans ce système, l'expression du TRE-Smpd3 sera induite par l'activation du transactivateur rtTA sous le contrôle du promoteur ubiquitaire ROSA par la Dox uniquement dans les cellules synthétisant la protéine rtTA. Après avoir traité les souris gestantes avec de la Dox, les embryons fro/fro;ROSA-rtTA;TRE-Smpd3 ont montré une minéralisation normale et une correction des membres déformés vers la fin de la gestation. Bien que les niveaux d'expression inductible de Smpd3 dépendaient de la dose de la Dox, aucune dose administrée n'a été suffisante pour complétement sauver les défauts de minéralisation de l'os ou le retard de croissance des os longs chez les adultes fro/fro;ROSA-rtTA;TRE-Smpd3. L'analyse du profil d'expression des gènes suggère que l'expression inductible de TRE-Smpd3 n'était pas assez forte pour pouvoir corriger les anomalies du squelette chez les souris adultes fro/fro;ROSA-rtTA;TRE-Smpd3.