Influence of the size of the microgap on crestal bone changes around titanium implants. A histometric evaluation of unloaded non-submerged implants in the canine mandible.

BACKGROUND: Endosseous implants can be placed according to a non-submerged or submerged approach and in 1- or 2-piece configurations. Recently, it was shown that peri-implant crestal bone changes differ significantly under such conditions and are dependent on a rough/smooth implant border in 1-piece implants and on the location of an interface (microgap) between the implant and abutment/restoration in 2-piece configurations. Several factors may influence the resultant level of the crestal bone under these conditions, including movements between implant components and the size of the microgap (interface) between the implant and abutment. However, no data are available on the impact of possible movements between these components or the impact of the size of the microgap (interface). The purpose of this study was to histometrically evaluate crestal bone changes around unloaded, 2-piece non-submerged titanium implants with 3 different microgap (interface) dimensions and between implants with components welded together or held together by a transocclusal screw. METHODS: A total of 60 titanium implants were randomly placed in edentulous mandibular areas of 5 hounds forming 6 different implant subgroups (A through F). In general, all implants had a relatively smooth, machined suprabony portion 1 mm long, as well as a rough, sandblasted, and acid-etched (SLA) endosseous portion, all placed with their interface (microgap) 1 mm above the bone crest level and having abutments connected at the time of first-stage surgery. Implant types A, B, and C had a microgap of < 10 microns, approximately 50 microns, or approximately 100 microns between implant components as did types D, E, and F, respectively. As a major difference, however, abutments and implants of types A, B, and C were laser-welded together, not allowing for any movements between components, as opposed to types D, E, and F, where abutments and implants were held together by abutment screws. Three months after implant placement, all animals were sacrificed. Non-decalcified histology was analyzed histometrically by evaluating peri-implant crestal bone changes. RESULTS: For implants in the laser-welded group (A, B, and C), mean crestal bone levels were located at a distance from the interface (IF; microgap) to the first bone-to-implant contact (fBIC) of 1.06 +/- 0.46 mm (standard deviation) for type A, 1.28 +/- 0.47 mm for type B, and 1.17 +/- 0.51 mm for type C. All implants of the non-welded group (D, E, and F) had significantly increased amounts of crestal bone loss, with 1.72 +/- 0.49 mm for type D (P < 0.01 compared to type A), 1.71 +/- 0.43 mm for type E (P < 0.02 compared to type B), and 1.65 +/- 0.37 mm for type F (P < 0.01 compared to type C). CONCLUSIONS: These findings demonstrate, as evaluated by non-decalcified histology under unloaded conditions in the canine mandible, that crestal bone changes around 2-piece, non-submerged titanium implants are significantly influenced by possible movements between implants and abutments, but not by the size of the microgap (interface). Thus, significant crestal bone loss occurs in 2-piece implant configurations even with the smallest-sized microgaps (< 10 microns) in combination with possible movements between implant components.     

Biologic Width around one- and two-piece titanium implants

Gingival esthetics around natural teeth is based upon a constant vertical dimension of healthy periodontal soft tissues, the Biologic Width. When placing endosseous implants, however, several factors influence periimplant soft and crestal hard tissue reactions, which are not well understood as of today. Therefore, the purpose of this study was to histometrically examine periimplant soft tissue dimensions dependent on varying locations of a rough/smooth implant border in one-piece implants or a microgap (interface) in two-piece implants in relation to the crest of the bone, with two-piece implants being placed according to either a submerged or a nonsubmerged technique. Thus, 59 implants were placed in edentulous mandibular areas of five foxhounds in a side-by-side comparison. At the time of sacrifice, six months after implant placement, the Biologic Width dimension for one-piece implants, with the rough/smooth border located at the bone crest level, was significantly smaller (P<0.05) compared to two-piece implants with a microgap (interface) located at or below the crest of the bone. In addition, for one-piece implants, the tip of the gingival margin (GM) was located significantly more coronally (P<0.005) compared to two-piece implants. These findings, as evaluated by nondecalcified histology under unloaded conditions in the canine mandible, suggest that the gingival margin (GM) is located more coronally and Biologic Width (BW) dimensions are more similar to natural teeth around one-piece nonsubmerged implants compared to either two-piece nonsubmerged or two-piece submerged implants.     

Arthroscopic capsular release for the treatment of refractory postoperative or post-fracture shoulder stiffness.

BACKGROUND: Arthroscopic capsular release is used to treat idiopathic adhesive capsulitis (frozen shoulder) that is refractory to nonoperative treatment or manipulation under anesthesia. The role of arthroscopic capsular release in the treatment of frozen shoulder after shoulder surgery or fracture is less clearly understood. The purposes of this study were to define the outcome of arthroscopic capsular release in the management of frozen shoulder after surgery or fracture and to compare these results with those of arthroscopic capsular release in the treatment of idiopathic frozen shoulder. METHODS: We evaluated the results of arthroscopic capsular release in three different groups of patients with shoulder contracture refractory to nonoperative management and manipulation under anesthesia. The three groups consisted of patients who had an idiopathic frozen shoulder, shoulder stiffness after surgery, or shoulder stiffness after fracture. We evaluated pain, function, patient satisfaction, and range of motion in all three groups before and after the study treatment. RESULTS: At a mean of twenty months (range, twelve to forty-six months) after the operation, fifty patients were available for assessment of function and range of motion of the involved shoulder. At the time of follow-up, each group had a significant improvement in the scores for pain, patient satisfaction, and functional activity as well as in the overall outcome score (p < 0.01). Comparison of the scores among the different groups revealed that all had a similar degree of improvement in range of motion of the involved shoulder, but patients with postoperative frozen shoulder had significantly (p < 0.05) lower scores for pain (p < 0.03), patient satisfaction (p < 0.004), and functional activity (p < 0.002) than did those with idiopathic or post-fracture frozen shoulder. CONCLUSIONS: Arthroscopic capsular release was as effective for improving range of motion in patients with postoperative contracture of the shoulder as it was in patients with idiopathic and post-fracture contracture. However, there was less improvement in the subjective scores for pain, function, and patient satisfaction in the postoperative group.     

Cytokine regulation of proliferation and cell adhesion are correlated events in human CD34+ hemopoietic progenitors

Adhesive interactions with the extracellular matrix of the bone marrow (BM) stroma are of critical importance in the regulation of hematopoiesis. In part, these interactions are presumed to play an important role in retaining CD34+ hematopoietic progenitor cells (HPCs) within the BM environment, in close proximity with BM stromal cells and the cytokines they produce. Evidence of a more direct role for cell adhesion in the regulation of hematopoiesis is provided by recent data showing that adhesive interactions can also provide important costimulatory signals. We have previously shown that normal CD34+ HPCs express high levels of fibronectin (Fn) receptors very late antigen-4 (VLA-4) and VLA-5 in a low-affinity state, which do not allow HPCs to strongly adhere on immobilized Fn, and that cytokines such as interleukin-3, granulocyte-monocyte colony-stimulating factor, and stem cell factor transiently activate these receptors, providing HPCs with an adhesive phenotype on Fn. Thus, knowledge of the functional states of adhesion receptors is critical to our understanding of the physiological mechanisms responsible for the regulation of normal hematopoiesis. Herein, we show that combinations of cytokines that synergize to stimulate the proliferation of CD34+ HPCs result in additive stimulation of the adhesion of these cells to Fn. Thus, the activation level of Fn receptors expressed by normal CD34+ HPCs is highly correlated with their proliferative state, suggesting a functional link between these two events. Therefore, we propose a 2- step model with an initial activation of VLA-4 and VLA-5 generated by cytokine receptors that is followed by a secondary signal resulting from Fn binding to VLA-4 and VLA-5, which may cooperate with those generated by cytokine receptors.     

Long-term treatment with oral sildenafil in addition to continuous IV epoprostenol in patients with pulmonary arterial hypertension

OBJECTIVES: To evaluate the effect of long-term oral therapy with sildenafil in patients with pulmonary arterial hypertension receiving long-term IV epoprostenol. DESIGN: Open, uncontrolled trial. SETTING: University hospital. PATIENTS: Two patients with primary pulmonary hypertension and one patient with pulmonary arterial hypertension after surgical closure of an atrial septal defect. All patients were receiving continuous epoprostenol for 1.7 to 7.1 years; two patients also received inhaled iloprost for 1.8 years and 3.8 years, respectively. INTERVENTIONS: Addition of oral sildenafil, up to 200 mg/d, divided in four to six single doses, and hemodynamic measurements and the 6-min walking distance (6MWD) before and after 5 months of treatment with sildenafil. RESULTS: One patient was treated with sildenafil, 200 mg/d; two patients received 75 mg/d due to nausea and headache. Long-term treatment with sildenafil in the three patients reduced mean pulmonary artery pressure by 14%, 41%, and 22%, respectively; in two patients, pulmonary vascular resistance was decreased by 52% and 55%. The 6MWD increased by 34%, 6%, and 29%, respectively. No significant systemic hypotension or decrease of arterial oxygen saturation was seen. CONCLUSION: Sildenafil therapy may be of benefit in patients with pulmonary arterial hypertension receiving long-term infusion of epoprostenol.     

Reductions in physiologic shear rates lead to CD11/CD18-dependent, selectin-independent leukocyte rolling in vivo

In this study, we tested the hypothesis that reducing shear rates in postcapillary venules causes CD18-dependent, selectin-independent leukocyte rolling. Intravital microscopy was used to assess shear rate- dependent leukocyte rolling in 25- to 40-microns rat mesenteric venules. Pretreatment of animals with 25 mg/kg fucoidin, a carbohydrate moiety that binds to and inhibits selectin function, essentially abolished the number of spontaneously rolling leukocytes. When shear rates were reduced by 50% (from 438 +/- 36 s-1 to 222 +/- 19 s-1) in the presence of fucoidin, leukocyte rolling increased fourfold, suggesting a selectin-independent mechanism of leukocyte rolling. Administration of CL26, an anti-CD18 antibody, prevented the leukocyte rolling associated with reduced shear rates. A second objective was to determine if the integrin-mediated leukocyte rolling at reduced shear rates would lead to firm adhesion of leukocytes in the presence of a chemotactic stimulus. Animals were pretreated with fucoidin and 100 nmol/L platelet-activating factor (PAF) was superfused over the mesentery. Fucoidin prevented leukocyte rolling and subsequent PAF- induced adhesion at normal shear rates; however, when shear rates were reduced by 50%, a significant CD18-dependent increase in leukocyte rolling (10-fold) and adhesion (5-fold) was noted within 15 minutes. These data raise the possibility that, at lower shear rates, as is the case in various inflammatory conditions, selectin-independent, CD18- dependent leukocyte rolling and subsequent adhesion can occur in postcapillary venules.     

Aerosolized iloprost therapy could not replace long-term IV epoprostenol (prostacyclin) administration in severe pulmonary hypertension

OBJECTIVES: To switch patients with severe pulmonary hypertension and previous life-threatening catheter-related complications from long-term IV epoprostenol therapy to aerosolized iloprost therapy. DESIGN: Open, uncontrolled trial. SETTING: Medical ICU of a university hospital. PATIENTS: Two patients with primary pulmonary hypertension and one patient with pulmonary hypertension after surgical closure of atrial septal defect (mean pulmonary artery pressure > or =50 mm Hg). All were classified as New York Heart Association class II under treatment with continuous IV epoprostenol for 4 years. INTERVENTIONS: Stepwise reduction of IV epoprostenol (1 ng/kg/min steps every 3 to 10 h) during repeated inhalations of aerosolized iloprost (150 to 300 microg/d with 6 to 18 inhalations/d). Continuous pulmonary and systemic arterial monitoring were performed. RESULTS: Aerosolized iloprost reduced pulmonary artery pressure by 49%, 49%, and 45%, respectively, and increased cardiac output by 70%, 75%, and 41% in the three patients. The effect lasted for 20 min and was similar at different doses of IV epoprostenol. Persistent treatment change to inhaled iloprost could not be achieved because all patients developed signs of right heart failure. After termination of iloprost inhalations, return to standard epoprostenol therapy led to clinical and hemodynamic restoration. CONCLUSIONS: Although aerosolized iloprost demonstrated short-term hemodynamic effects, it could not be utilized as alternative chronic vasodilator in patients with severe pulmonary hypertension.     

Cytogenetic studies and their prognostic significance in agnogenic myeloid metaplasia: a report on 47 cases

Cytogenetic analysis was performed in 47 newly diagnosed patients with agnogenic myeloid metaplasia (AMM); 32 had a normal karyotype (68%, group I), whereas 15 had clonal abnormalities (32%, group II). The most frequent abnormal findings were a 20q- deletion in six cases (either alone or within complex anomalies), interstitial 13q- deletion in three cases (and monosomy 13 in one case), and acquired trisomy 21 or 21p+ in three cases. Four cases exhibited complex aberrations involving several chromosomes, sometimes with a mosaicism. In two patients with an initial abnormal karyotype, further cytogenetic analysis during the disease course showed the appearance of additional clonal anomalies, and particularly of a probable Philadelphia (Ph1) variant in one case. Treatment was essentially supportive. Survival was significantly shorter in group II (median, 30 months) compared with group I (median, not reached at 6 years; P = .015). In univariate analysis, other parameters significantly associated with a poor prognosis (P less than .05) were higher age, anemia, and increased percentage of circulating blasts. However, in a multivariate analysis, only cytogenetic abnormalities and age retained their independent prognostic value.     

Artérite de Takayasu: explorations vasculaires et prise en charge thérapeutique. Expérience à propos de 16 patients

Purpose. -- There is no consensus in regard to vascular explorations and therapeutical management of Takayasu's arteritis. The objective of this study was therefore to establish the most appropriate vascular explorations and to analyze current treatments.Methods. -- Clinical, biological and morphological findings related to either diagnosis or treatment were retrospectively evaluated in sixteen patients diagnosed with Takayasu's arteritis according to the American College of Rheumatology criteria.Results. -- Median delay between the occurrence of the first symptoms and the diagnosis was 9 months. Aortic lesions and aortic valvular incompetence were more frequent. Statistical analysis showed the existence of a correlation between the lack of relapse and corticosteroid therapy (Fisher exact test, P = 0,021). Percutaneous transluminal angioplasty led to stabilization of vascular lesions. Surgical management led to satisfactory results, except for patients with aortic lesions, as survival was then less than 1 year.Conclusion. -- Early diagnosis is mandatory in patients with Takayasu's arteritis in order to propose appropriate therapy, particularly corticosteroid therapy. Surgery and angioplasty prove to be useful in occlusive forms. Late diagnosis is accompanied by severe aortic lesions and fatal outcome.

Résumé

Propos. -- Dans le cadre de l'artérite de Takayasu, il n'existe pas de consensus concernant les explorations vasculaires et la prise en charge thérapeutique. L'objectif de notre étude était d'analyser chez 16 malades souffrant d'artérite de Takayasu les méthodes d'exploration les plus adaptées et les traitements employés.Méthodes. -- Seize patients atteints d'artérite de Takayasu selon les critères de l'American College of Rheumatology ont été évalués de façon rétrospective de 1975 à 1997, cliniquement, biologiquement, morphologiquement, sur le plan diagnostic et thérapeutique.Résultats. -- Dans notre série, la médiane de retard diagnostique était de 9 mois. L'atteinte aortique et valvulaire aortique était plus fréquente. Les résultats ont montré l'existence d'une corrélation statistiquement significative entre l'absence de rechute et l'emploi des corticoïdes (test exact de Fisher, p = 0,021). L'utilisation de l'angioplastie a entraîné une stabilisation des lésions. La prise en charge chirurgicale s'est montrée satisfaisante, en dehors des patients ayant une atteinte aortique pour lesquels la survie était inférieure à 1 an.Conclusion. -- L'analyse de notre série montre la nécessité d'un diagnostic précoce afin de proposer une thérapeutique adéquate, en particulier la corticothérapie. La chirurgie et l'angioplastie sont des recours efficaces en cas de forme occlusive. Les formes diagnostiquées tardivement comportent une atteinte aortique sévère dont l'évolution est le plus souvent fatale.