Bone augmentation at titanium implants using autologous bone grafts and a bioresorbable barrier. An experimental study in the rabbit tibia

The aim of the present investigation was to compare the effect of using autologous bone particles covered with a bioresorbable matrix barrier with the use of bone particles alone on bone augmentation at titanium implants installed in the rabbit tibia. Two Br?nemark System implants, one in each tibia, were inserted in each of 9 rabbits in such a way that 5 threads were not covered with bone. Autologous bone particles were harvested from the skull and placed over the exposed implant surfaces on each tibia. The bone graft on one tibia was covered with a Guidor Matrix Barrier, while the bone graft on the other tibia served as a control. After a healing period of 12 weeks, the animals were sacrificed and specimens taken for histomorphometrical analyses. The analyses showed that a significantly larger volume of augmented bone tissue had formed at the test sites. There were, however, no differences in the amount of mineralized bone. In fact, the difference in tissue volume was due to an increased amount of bone marrow at the test sites. The degree of mineralized bone to implant contact as well as the degree of mineralized bone within the threads at the test implants were similar to that at the controls. In conclusion, it was found that the coverage of particulate autologous bone grafts with a bioresorbable barrier resulted in a larger volume of augmented bone than the use of bone grafts not covered with a barrier.     

Guided bone regeneration in long bone. An experimental study

To assess the satisfaction with the department and hospital services provided by a medium-size community hospital during a 2 month period (April-May 1995), 118 randomly chosen patients were asked to complete a questionnaire designed to reflect their opinions during hospitalization. The principal points of the survey concerned the general perception regarding the services in the department and the hospital, the admission and discharge procedures, the quality of food and sanitary conditions, an evaluation of the physicians' and nurses' skill and attitude, as well as their compliance to patients' needs. Overall satisfaction with the medical care was very high, the physicians' attitude and nurses' compliance being the two most important determinants. The role of this type of questionnaire as an instrument for improving health services is emphasized.     

Vertical ridge augmentation around dental implants using a membrane technique and autogenous bone or allografts in humans

This study investigated the effect on vertical bone regeneration of the addition of demineralized freeze-dried bone allograft or autogenous bone chips to a membrane technique. Twenty partially edentulous patients with vertical jawbone deficiencies were selected for this study. The patients were divided into two groups of 10 individuals. The 10 patients of Group A received 26 Br?nemark implants in 10 surgical sites. The 10 patients of Group B received 32 implants in 12 surgical sites. Fifty-two out of 58 implants (22 in Group A and 30 in Group B) extended 1.5 to 7.5 mm superior to the bone crest. Titanium-reinforced expanded polytetrafluoroethylene membranes were used to cover the implants and, before complete membrane fixation, demineralized freeze-dried bone allograft particles were condensed under the membrane in Group A, and autogenous bone chips were used in Group B. At the reentry after 7 to 11 months the membranes were removed and a small biopsy was collected from 11 sites comprehending the miniscrews. The clinical measurements from Group A demonstrated a mean vertical bone gain of 3.1 mm (SD = 0.9 mm, range 1 to 5 mm) with a mean percentage of bone gain of 124% (SD = 46.6%). The measurements from Group B showed a mean vertical bone gain of 5.02 mm (SD = 2.3 mm, range 1 to 8.5 mm) with a mean percentage of bone gain of 95% (SD = 26.8%). Histomorphometric analysis of the present study clearly demonstrated a direct correlation between the density of the pre-existing bone and the density of the regenerated bone. The mean percentage of new bone-titanium contact was from 39.1% to 63.2%, depending on the quality of the pre-existing bone. Both the clinical and histologic results indicate a beneficial effect of the addition of demineralized freeze-dried bone allograft or autogenous bone particles to vertical ridge augmentation procedures in humans.     

Guided bone regeneration in dental implant treatment using a bioabsorbable membrane

1. Australia has some of the most venomous fauna in the world. Although humans are not usually perceived as being predators against these animals they are often envenomated, accidentally or otherwise. This has led to the development of antivenoms against some of the potentially lethal venoms. However, further understanding of the mechanism(s) of action of these and other venoms is important, not only for developing new treatment strategies but also in the search for novel research tools. 2. The present review discusses the pharmacology of some of the components found in venoms and outlines the research undertaken on some of Australia's venomous animals, with the exception of snakes. 3. Biogenic amines, peptides and enzymes are common venom components and produce a wide range of effects in envenomated humans. For example, respiratory failure observed after envenomation by the box jellyfish (Chirnex fleckeri) and Sydney funnel-web spider (Atrax robustus) is most likely due to potent neurotoxins in the venoms. Stonefish (Synanceja trachynis) and platypus (Ornithorhynchus anatinus) venoms, although not considered lethal, cause severe pain. However, the components responsible for these effects have not been isolated. Venom components, as yet unidentified, may be responsible for the cutaneous necrotic lesions that have been reported after some spider bites (e.g. Lampona cylindrata). Other venoms, such as those of the jumper ant (Myrmecia pilosula) and bull ant (M. pyriformis), may produce only mild skin irritation to the majority of humans but a severe anaphylactic response in sensitized victims. 4. While there has been a renewed interest in toxinology, further research is required to fully elucidate the pharmacological action of many of these venoms.     

Supracrestal bone regeneration around dental implants using a calcium carbonate and a fibrin-fibronectin sealing system: clinical and histologic evidence

This study evaluated a new surgical technique for the treatment of an alveolar ridge deficiency in 11 patients. Twenty-two implants were placed, 15 of which presented with a combination of supracrestal and dehiscence kinds of defects, and seven presented only supracrestal bone loss. Surgical procedures were performed utilizing a combination of the resorbable space-making material calcium carbonate stabilized with a fibrin-fibronectin sealing system and the immediate placement of titanium dental implants. After implant placement, the mean height for supracrestal and dehiscence defects measured 2.57 +/- 1.41 mm and 2.47 +/- 1.54 mm, respectively. The defects were filled with calcium carbonate and a fibrin-fibronectin sealing system, and the flaps were sutured, avoiding any compression of the treated area. Healing was uneventful in all instances. At second-stage surgery at 6 months, a hard bone-like tissue was detectable at the defect sites. Histologic examination of four defects confirmed the presence of newly formed bone and revealed residual particles of calcium carbonate. There was a mean gain of 2.05 +/- 1.47 mm in the supracrestal defects and of 2.23 +/- 1.62 mm in the dehiscences. The results indicated that calcium carbonate, combined with a fibrin-fibronectin sealing system, is a viable alternative in the treatment of supracrestal and dehiscence bony defects.     

Blood-filled spaces with and without filler materials in guided bone regeneration. A comparative experimental study in the rabbit using bioresorbable membranes

We evaluated the correspondence between in-person- and telephone interview-derived data on affective symptoms, health-related quality of life, disability days, and medication compliance in patients with bipolar disorder. Twenty-eight outpatients with DSM-III-R-documented bipolar disorder were randomly assigned to an initial in-person or telephone interview. An average of 4.0 days later, they were reassessed by the other interview method. Results indicate good to excellent agreement between telephone and in-person interviews on measures of mania (intraclass correlation coefficient (ICC) = 0.92) and depression symptoms (ICC = 0.90), suicide risk (kappa = 0.80), and alcohol use (kappa = 0.61), scores on the Medical Outcomes Study 36-item Short-Form Health Survey (ICCs = 0.66-0.92), and medication compliance (ICCs = 0.50-0.66). Measures of bed disability days (ICC = 0.34) and restricted activity days (ICC = 0.66) showed less agreement. Telephone interviews are feasible and reliable for collecting data on psychiatric and other health-related outcomes in bipolar disorder patients.     

Effects of guided bone regeneration around commercially pure titanium and hydroxyapatite-coated dental implants. II. Histologic analysis

The purpose of this study was to determine which treatment of a large osseous defect adjacent to an endosseous dental implant would produce the greatest regeneration of bone and degree of osseointegration: barrier membrane therapy plus demineralized freeze-dried bone allograft (DFDBA), membrane therapy alone, or no treatment. The current study histologically assessed changes in bone within the healed peri-implant osseous defect. In a split-mouth design, 6 implants were placed in edentulous mandibular ridges of 10 mongrel dogs after preparation of 6 cylindrical mid-crestal defects, 5 mm in depth, and 9.525 mm in diameter. An implant site was then prepared in the center of each defect to a depth of 5 mm beyond the apical extent of the defect. One mandibular quadrant received three commercially pure titanium (Ti) screw implants (3.75 x 10 mm), while the contralateral side received three hydroxyapatite (HA) coated root-form implants (3.3 x 10 mm). Consequently, the coronal 5 mm of each implant was surrounded by a circumferential defect approximately 3 mm wide and 5 mm deep. The three dental implants in each quadrant received either DFDBA (canine source) and an expanded polytetrafluoroethylene membrane (ePTFE), ePTFE membrane alone, or no treatment which served as the control. Clinically, the greatest increase in ridge height and width was seen with DFDBA/ePTFE. Histologically, statistically significant differences in defect osseointegration were seen between treatment groups (P < 0.0001: DFDBA/ePTFE > ePTFE alone > control). HA-coated implants had significantly greater osseointegration within the defect than Ti implants (P < 0.0001). Average trabeculation of newly formed bone in the defect after healing was significantly greater for HA-coated implants than for titanium (P < 0.0001), while the effect on trabeculation between treatments was not significantly different (P = 0.14). Finally, there were significantly less residual allograft particles in defect areas adjacent to HA-coated implants than Ti implants (P = 0.0355). The use of HA-coated implants in large size defects with DFDBA and ePTFE membranes produced significantly more osseointegration histologically than other treatment options and more than Ti implants with the same treatment combinations. The results of this study indicate that, although the implants appeared osseointegrated clinically after 4 months of healing, histologic data suggest that selection of both the implant type and the treatment modality is important in obtaining optimum osseointegration in large size defects.     

The effects of guided bone regeneration and grafting on implants placed into immediate extraction sockets. An experimental study in dogs

Guided bone regeneration (gbr) for the treatment of insufficient bone volume around implants can be performed using membranes with or without grafting materials (i.e., autogenous, allogenous, xenogenous, or alloplastic grafts). A possible way to evaluate the quality of implant osseointegration is the torque necessary to remove implants from their bony housing. The aim of this study was to compare the torques necessary to remove dental implants from implant beds reconstructed with different bone substitutes and GBR or GBR alone in 6 adult mongrel dogs. All mandibular premolars were extracted and 3 extraction sockets on each side were enlarged using a trephine bur. A 13 mm titanium screw-type dental implant (3.75 mm diameter) was placed in each enlarged extraction socket so that only the apical 3 to 4 mm were engaged in bone. The 3 defects were then randomly treated with either 1) canine demineralized freeze-dried bone allograft (DFDBA) plus GBR using an expanded polytetrafluoroethylene membrane (DFDBA+GTAM); 2) bioabsorbable hydroxyapatite and GBR (HA+GTAM); or 3) GBR (GTAM alone). After 6 months, the torque to remove the implants was measured in 4 animals and analyzed using ANOVA. There were no statistically significant differences between the 3 groups (GTAM alone: 46.37+/-16.41 Ncm; HA+GTAM: 46.00+/-16.59 Ncm; DFDBA+ GTAM: 52.15+/-29.24 Ncm). In addition, the influence of early removal of barriers on the torque values was evaluated with the t-test. Comparing exposed versus retained membranes by treatment modality, the only statistically significant difference was found in the DFDBA+GTAM group. When the torque values of all implants with exposed and retrieved membranes were compared to all those with retained membranes a significant difference could be detected. Histologic sections were prepared from the 2 dogs not included in the removal torque testing. In the histometric analysis the GTAM alone group showed a mean mineralized bone-to-implant-contact of 27.1%, the DFDBA+GTAM group of 34.6%, and the HA+GTAM of 39.3%. The mineralized bone-to-implant-contact of the HA+GTAM group was significantly higher than that of the GTAM alone group. In addition, the mineralized bone-to-implant-contact was divided into an apical and coronal part using the apical seventh thread as the dividing landmark. In the apical region, there was no significant difference between the groups regarding mineralized bone-to-implant-contact. In the coronal part the mineralized bone-to-implant-contact of the GTAM alone group was significantly lower compared to the other 2 groups. Within the limits of this investigation, it can be concluded that the type of grafting material will not influence torque removal values, but that early membrane exposure and removal will negatively influence the torque measurements. The combination of GBR with a bone substitute increased the mineralized bone-to-implant contact.     

Influence of barrier occlusiveness on guided bone augmentation. An experimental study in the rat

OBJECTIVE: To investigate the relationships between self-assessed financial difficulties, diet in pregnancy and birthweight. DESIGN: Information on diet composition, difficulty in affording food, smoking habits and parity was collected by self-completion questionnaires at 32 weeks of pregnancy. Information on birthweights was obtained from hospital records. SUBJECTS: A geographically defined population 11833 pregnant women resident in the South-West of England. MAIN OUTCOME MEASURES: Nutrient intakes, food choices and birthweight. RESULTS: Women with greater difficulty in affording food had lower intakes of protein, fibre, vitamin C, niacin, pyridoxine, iron, zinc, magnesium and potassium than did women with little or no difficulty. They were more likely to use cooking and spreading fats with a high saturates content, and less likely to eat fish, fruit, vegetables and salad. In a multivariate analysis including parity and smoking status, financial difficulty was found to have no significant relationship with birthweight. CONCLUSION: The quality of diet in pregnancy falls with increasing difficulty in affording food. However, this does not appear to affect mean birthweight of infants born after 32 weeks gestation.     

The influence of the design of two different bioresorbable barriers on the results of guided tissue regeneration therapy. An intra-individual comparative study in the monkey

The aim of the present study was to compare two bioresorbable barriers to evaluate whether differences in design influence the result of guided tissue regeneration (GTR) therapy. Twenty-four (24) plaque exposed, recession type defects in 4 monkeys were treated. Contralateral defects were randomized for test or control treatment. During a healing period of 6 weeks, gingival recession resulting in device exposure occurred at 3 test and 10 control sites. One control barrier was exfoliated. Histologically, 9 of the 12 test barriers were completely integrated with the surrounding tissues. At 3 test sites, epithelium had migrated apically outside the barrier to a level not exceeding one-third of the height of the device. Seven of the 11 control barriers were enclosed by dentogingival epithelium. The adjacent connective tissue exhibited local inflammatory cell infiltrates (ICT). At the remaining 4 control sites, the epithelial downgrowth as well as the adjacent ICT areas were limited to the coronal 1/3 of the device. New attachment; i.e., new cementum with inserting collagen fibers, averaged 2.2 mm and 0.8 mm at the test and control sites respectively (P < 0.01). Based on the results of the present study, it was concluded that a bioresorbable GTR device, designed to prevent epithelial downgrowth along the barrier surface, has a higher potential to promote new attachment formation than a device which does not have this property.     

Measurements of stability changes of titanium implants with exposed threads subjected to barrier membrane induced bone augmentation. An experimental study in the rabbit tibia

The present study was undertaken to investigate the relationship of microglial activation to amyloid beta protein (A beta) deposition, particularly at the early stage. Using single and double immunostaining methods with a panel of microglia markers and antibodies against A beta and amyloid beta protein precursor (APP), we examined the cerebrum and cerebella of both Alzheimer's disease (AD) and non-demented subjects obtained at autopsy. In nondemented, middle-aged subjects that had small amounts of cerebral A beta deposits, approximately 70% of the diffuse plaques contained ramified microglia. However, no evidence of microglial activation was found in diffuse plaques in any of the non-demented subjects. Dual immunostaining of sections of cerebral cortex using antibodies against A beta and major histocompatibility complex class II antigen showed that in AD subjects, approximately 20% of total diffuse plaques contained a few, activated microglia. Most of these plaques were defined as a transitional from between diffuse and primitive plaques. Both primitive and classic plaques in the cerebral cortex of AD subjects consistently contained clusters of activated microglia. Subpial A beta deposits without neuritic changes lacked microglial activation. In the cerebellum, all of the diffuse plaques lacked microglial activation, and activated microglia in the compact plaques were not as hypertrophic as those in cerebral primitive/classic plaques. Our findings indicate that microglial reactions are absent in the early stages of A beta deposition, and it occurs during the transition from diffuse to primitive plaques, when amounts of A beta deposits and the degree of neuritic changes increase.     

Guided tissue regeneration using bioresorbable membranes: what is the limit in the treatment of combined periapical and marginal lesions?

The maintenance of single teeth may often be of crucial importance for the prognosis of the total dentition. In such cases, as when a single tooth supports a fixed partial denture, a special effort should be made to maintain that tooth. This study reports the treatment of six such terminal cases. The results of a combination of local and systemic antibiotics and the use of guided tissue regeneration with resorbable membranes and grafting material is demonstrated. After defect debridement and root planing, the defects were filled with Biostite (Coletica), and Paroguide (Coletica) membranes were placed. The results at reentry demonstrated the efficacy of these treatments, and all six treatments were considered successful. The influence of the individual components used in treatment is discussed.     

The regenerative potential of oxytalan fibers. An experimental study in the monkey

Although a number of studies have described the oxytalan fibers as being a natural component of the periodontal ligament, little information exists about the regenerative potential of these connective tissue fibers. The aim of the present study was to examine whether oxytalan fibers have the capacity to reform after regenerative periodontal therapy. Intrabony defects were produced surgically at the mesial aspects of teeth 37, 35, 45, 47 and at the distal aspects of teeth 11, 21, 31, 41 in one monkey (Macaca fascicularis). After 3 months, the defects were exposed using a full-thickness flap procedure. The root surfaces were debrided and subsequently PDGF-growth factors were placed in the defects. 4 of the 8 sites were covered with a bioresorbable membrane before closure of the wound. Post-surgically, antibiotics were given systemically for 1 week, and tooth cleaning was carried out 1x a week during the entire experimental period. After 5 months, the animal was sacrificed and the oral tissues were fixed by perfusion with 10% buffered formalin. Specimens containing the defects and surrounding tissues were dissected free and histological sections were cut in the mesio-distal direction, parallel to the long axes of the teeth. The sections were stained with hematoxylin and eosin or with the oxone-aldehyde-fuchsin-Halmi staining method and subsequently examined in the light and in the electron microscope. The results revealed that new oxytalan fibers oriented mainly in an apico-occlusal direction had developed in the regenerated periodontal ligament. Many of the newly-formed fibers were inserted into the new cementum, thus suggesting a strong relationship between this tissue and the oxytalan fibers. It is concluded that the regenerated periodontal ligament connective tissue formed after surgery contains oxytalan fibers similar to those present in the original tissue. These results demonstrate that oxytalan fibers develop de novo in the newly-formed periodontal ligament.     

Guided tissue regeneration therapy of 203 consecutively treated intrabony defects using a bioabsorbable matrix barrier. Clinical and radiographic findings

We report a 64-year-old woman who developed nausea, headache, and consciousness disturbance. She was well until four years before the onset of her neurologic illness when (April of 1990 at her 59 years of the age) she was found to have an early cancer in her anterior wall of the lower stomach. Subtotal gastrectomy was performed and the operative result was reported as curative. Four years after the surgery (December of 1994 at her 64 years of the age), she noted suboccipital headache and nausea which had become progressively worse and she was admitted to our service on May 24, 1995. On admission, she appeared chronically ill but general physical examination was unremarkable with normal vital signs. Neurologically she was alert and not demented, and the higher cerebral functions were intact. Cranial nerves were also unremarkable. She was able to walk in tandem and on heels. No motor weakness or ataxia was noted. Deep tendon reflexes were moderately increased, however, no Babinski sign was noted. Although she had headache, no meningeal signs were seen. Slight superficial and vibratory sensory loss was noted in both feet. Routine blood work was again unremarkable except for slight increase in CEA to 8.3 ng/dl (N < 5 ng/dl). The opening pressure of lumbar CSF was 180 mm H2O and the CSF contained 39 cells/microliter, 79 mg of protein, and 10 mg/dl of glucose. Approximately half of the cells were atypical malignant cells. Plain CT was unremarkable, however, tentorial border showed enhancement after contrast infusion. FGS showed no malignant tumors in the stomach. She was treated with intravenous glycerol and whole brain radiation, however, she continued to complain of severe headache, and her sensorium started to be disturbed one month after the admission. Follow-up cranial CT scan revealed enlargement of the lateral and the third ventricles. Her consciousness progressively deteriorated and she became comatose three months after the admission. Repeated cranial CT scan showed enlargement of the ventricles, but no mass lesions were seen within the brain. She developed respiratory arrest on September 25 of the same year. She was discussed in a neurological CPC and the chief discussant arrived at the conclusion that the patient had a gastric cancer with meningeal seeding developing meningeal carcinomatosis. The cause of deep coma was ascribed to damage of cerebral cortical areas secondary to metastatic carcinoma cells and fibrinous materials in the surface of the brain. Postmortem examination revealed thickening and clouding of leptomeninges of the cerebral convexity. On histologic observation, patchy areas of fibrous thickening were seen in the cerebral leptomeninges; in such areas, adenocarcinomatous cells were seen scattered. The basal meninges were free of carcinoma cells, however, leptomeninges of the cerebellum and brain stem tegmentum contained scattered carcinoma cells. The lateral and the third ventricles were enlarged, however, insides of the brain were free of pathologies; the ependymal layer were intact. In the stomach no carcinoma cells were remaining. Pneumonic changes were seen in the right upper and the left lower lobes which appeared to be the direct cause of her death. No evidence of tentorial herniation was noted. The cause of her deep coma was not clearly determined, however, combination of hydrocephalus and cortical malfunction due to leptomeningeal carcinoma cell infiltration and fibrinous material accumulation appeared to have played a role.     

Influence of metal implants on infection. An experimental study in rabbits

We implanted cylinders of cobalt-chrome or titanium, with smooth or porous surfaces, into rabbit bones which had been inoculated with suspensions of Staphylococcus aureus in various doses. The bacterial concentration required to produce infection of porous-coated titanium implants was 2.5 times smaller than that necessary to infect implants with polished surfaces. Porous-coated cobalt-chromium implants required bacterial concentrations that were 40 times smaller than those needed to infect implants with polished surfaces, and 15 times smaller than those required to infect porous-coated titanium implants. The other advantages and disadvantages of the various implants, such as improved osseointegration, larger ion-release surfaces, surface wear and relative stiffness, must be weighed against the higher infection rates in the porous-coated implants, and particularly in the cobalt-chromium implants.     

Reintegration of mobilized titanium implants. An experimental study in rabbit tibia

BACKGROUND: Microsatellites are short repetitive nucleotide sequences that, through mutation, can undergo either expansion or contraction. This novel mutational mechanism known as microsatellite instability may play a role in carcinogenesis. We investigated the incidence of microsatellite instability in a series of primary breast carcinoma surgical specimens. METHODS: Using polymerase chain reaction techniques followed by polyacrylamide/urea gel electrophoresis, we analyzed 46 pairs of normal and primary breast tumor samples at seven different microsatellite loci, five of which were located on chromosome 17. RESULTS: Thirteen of our 46 tumors (28.2%) demonstrated microsatellite instability. Five tumors (10.8%) were unstable at two or more loci, and of those, four (8.7%) were unstable at different loci on different chromosomes. An additional five tumors demonstrated loss of heterozygosity alone when compared with their normal counterparts. CONCLUSIONS: These findings indicate that microsatellite instability is present in primary breast cancer populations and, although the mechanism of action has yet to be elucidated, may play a role in breast carcinogenesis.     

Guided tissue regeneration for the treatment of intraosseous defects using a biabsorbable membrane. A controlled clinical study

The aim of this controlled, clinical study was to evaluate guided tissue regeneration using a bioabsorbable membrane in periodontal intraosseous defects. Forty patients, each contributing one defect > or =4 mm in depth participated. The control group (18 individuals) received conventional flap therapy, while the test group (22 individuals) was treated using the bioabsorbable membrane, Guidor. Clinical assessments were made by one examiner, blinded with respect to treatment group, at baseline, 6 and 12 months following surgery. Baseline probing pocket depths of 7.7+/-1.4 mm in the membrane group and 7.6+/-1.9 mm in the control group were measured. Twelve month results showed a significant clinical attachment level gain in both control (1.1+/-1.8 mm), and membrane group (1.3+/-2.1 mm). Probing pocket depth reduction of 2.6+/-1.9 mm and 2.7+/-1.9 mm was observed in the respective groups. Bone sounding showed a non-significant gain of 0.4+/-1.8 mm and 0.6+/-1.4 mm at membrane and control sites, respectively. Radiographic evaluation confirmed these results. There were no significant differences found between treatment groups for any of the tested variables. Smoking had a negative effect on healing in both groups. In conclusion, clinical and radiographic results indicate that guided tissue regeneration using a bioabsorbable membrane at intraosseous defects did not predictably achieve greater clinical attachment level gain nor bone gain when compared to conventional flap therapy.     

Radiographic analysis of regenerated bone around endosseous implants in the canine using recombinant human bone morphogenetic protein-2

A selective and sensitive HPLC method was developed for the determination of U-39968E in rat plasma. The assay involved solid-phase extraction of the analyte and the internal standard and precolumn derivatization with cyclohexane-1,3-dione reagent before injection on to the HPLC column. The samples were chromatographed on a Spherisorb S5 CN column (25 cm x 4.6 mm i.d.) with a mobile phase containing acetonitrile-trifluoroacetic acid-water (17:0.2:83, v/v/v) at a flow rate of 1.5 ml min-1. The column eluent was monitored by flourescence detection with excitation at 272 nm and emission at 320 nm. The assay is linear over the range 4-759 ng ml-1. The relative standard deviation at the limit of quantification, 4 ng ml-1, was 7.1%. This method was successfully applied to the determination of U-89968E in rat plasma during pharmacokinetic studies.     

Maxillary sinus augmentation using different grafting materials and dental implants in monkeys. Part I. Evaluation of anorganic bovine-derived bone matrix

The aim of this study was to evaluate clinically, histologically and histometrically the use of anorganic bovine bone matrix (i.e. Bio-oss) as a grafting material for maxillary sinus augmentation procedures. In 4 adult male rhesus monkeys (i.e. Macaca mulatta) the 1st, 2nd and 3rd maxillary molars on one side of the jaws were extracted. The remaining bone between the alveolar crest and the bottom of the sinus was then reduced to 3-4 mm. After 3 months, maxillary sinus augmentation procedures were performed on one side of the jaws in each monkey and the sinuses were grafted with the bovine bone matrix. At that time, 2 IMZ pure titanium plasma coated implants were immediately placed into the augmented sinuses (i.e. simultaneous implants-loaded group). After 4 months, 2 additional similar implants were placed into these previously augmented sinuses (i.e. delayed implants-loaded group). Four months later, the abutment connection was performed and all 4 implants were loaded with a gold-alloy bridge for 6 months (i.e. until sacrifice of the animals). The contralateral side of each monkey received the same treatment with the exception that the extractions were performed 7 months after those in the opposite side and that the implants in this side were not loaded. Thus, 2 additional study groups (i.e. simultaneous implants-unloaded group and delayed implants-unloaded group) were obtained. Clinically, all loaded implants were stable at the day of sacrifice. Histologically, the grafted sinuses exhibited significant bone formation with integration of the bovine bone matrix particles to the new bone. Direct mineralized bone-to-implant contact was greater for the delayed implant placement groups than for the implants installed simultaneously with the sinus augmentation. Furthermore, the percentage of direct mineralized bone-to-implant contact was greater in the residual bone than in the augmented area. It was concluded that the anorganic bovine bone matrix facilitated bone formation and implant osseointegration in the augmented sinuses and that the delayed implant placement in combination with the sinus augmentation procedure seemed to be preferable.