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PubMed2004

[Mechanical properties of human femoral head allografts after physico-chemical treatment (Osteopure)].

PURPOSE OF THE STUDY: Bone grafts and bone substitutes must be biocompatible osteoconductors with satisfactory mechanical properties similar to native bone. When the bone treatment is conducted under specific conditions, the elasticity module under infra-maximal loading can be optimized to achieve reproducible values. The purpose of this work was to determine the effect of the cleaning and sterilization process using Osteopure on the biomechanical properties of trabecular bone harvested from human femoral heads. MATERIAL AND METHOD: Seventy trabecular bone samples were tested: group 1F (fresh samples); group 1N (after application of Osteopure cleaning); group 1S (after Osteopure cleaning and sterilization). Non-destructive and destructive tests (group 1D) were performed. Two fresh femoral heads were used as controls for the destructive test (group 2). The first non-destructive test was applied directly after section (group 1F). Other samples were then purified with Osteopure treatment and a second non-destructive test was conducted (group 1N). A third non-destructive test was conducted after sterilization with 25 kgray radiation (group 1S). Treatments 1 and 2 were performed by OST Developpement SA (Clermont-Ferrand). Finally a destruction test was applied along the directional axis (group 1D). For the 31 samples in group 2 (control) the destructive test was applied along the directional axis immediately after section. Compression tests were performed at a deformation speed of 3 mm/min for 0.3% deformation. RESULTS: The Young module did not exhibit any significant difference between the three steps of the testing in the three orthogonal directions. The Young module was not significantly different between group 1F and group 2 (controls). Maximal force of compression was significantly different (P<0.01). There was a linear relationship between maximal force at rupture and the Young module obtained during destructive tests, for groups 1D and 2 respectively. The compression curves obtained from sterilized samples (group 1D) were not significantly different from those observed for fresh trabecular bone in group 2 (controls). DISCUSSION: The Young module values measured from 70-673 MPa. For non-destructive tests, the module values were to the order of 64% of those obtained for destructive tests. Decreased maximal force of rupture observed for treated samples in comparison with fresh samples can be explained by the extraction of most of the lipids. CONCLUSION: The Osteopure method does not alter stiffness of bone allografts. The elasticity module observed in treated bones is close to that observed in fresh bones. Mechanical resistance to compression is however only half the force of compression observed in the hip joint for daily activities. The linear relationship between the elasticity mode and loading required for rupture is not affected by treatment with Osteopure. The advantages related to elimination of prions or viral contamination appear by far to be more important than the minor changes observed in the mechanical characteristics of allografts.

Aged↗
PubMed2001

Biomimetic configurational arrays of hydroxyapatite nanocrystals on bio-organics.

Biomimetic configurational arrays of hydroxyapatite (HAp) nanocrystals on several bio-organics, collagen (Col), chondroitin sulfate (ChS), and their mixture, were comparatively studied. The nanocomposites of HAp/Col, HAp/ChS, and HAp/Col/ChS were synthesized through a precipitation method with calcium hydroxide suspension and phosphoric acid solution containing Col, ChS, and their mixture, respectively. The (0 0 2) diffraction of the synthesized HAp crystals on a Col fiber showed an around 60 arching angle, while that on a ChS fiber showed just around 10 degrees. The same configurational arrays of HAp crystals could also be obtained on the mixture of Col and ChS fibers. The different electron diffraction patterns of the HAp crystals on the Col and ChS fibers were explained by the different macromolecular configurations of the Col and ChS fibrils which compose their fibers. The results may be applicable to develop a bone substitute which mimics the peculiar configurational arrays of HAp crystals found in bone and their detailed organic composition.

Biocompatible Materials↗
PubMed2001

[Sinus floor augmentation with simultaneous implant insertion using recombinant human osteogenic protein-1].

INTRODUCTION: The purpose of this study was to examine whether the combination of an osteoinductive protein (recombinant human osteogenic protein-(rhOP-1 = bone morphogenetic protein-7) with natural bovine bone mineral (BioOss) would improve ossification and the bone-implant contact (BIC) in a sinus floor augmentation with simultaneous placement of implants. MATERIAL AND METHODS: In this study, the maxillary sinus floors in five miniature pigs were augmented with 3 ml BioOss containing 420 micrograms rhOP-1 on the test side and 3 ml BioOss alone on the control side. At the time of augmentation a titanium implant (ITI) was inserted from a laterocaudal direction. RESULTS: After 6 months of healing the sites of augmentation were removed and examined in non-decalcified sections by microradiography, fluorescence microscopy of sequentially labelled specimens and by histometry. On both sides, significant amounts of newly formed bone were observed. However, on the test sites, the BIC in the augmented area was 80.0% versus 38.6% on control sites. It can be concluded that the application of bone morphogenetic proteins caused a more rapid and enhanced osseointegration of simultaneously placed implants when compared to the bone substitute alone. DISCUSSION: Therefore recombinant human osteogenic protein-1 delivered by natural bone mineral has the potential to become a clinical alternative for autogenous bone grafts in sinus floor augmentation.

Animals↗
PubMed2005

STEM and EDXS characterisation of physico-chemical reactions at the periphery of sol-gel derived Zn-substituted hydroxyapatites during interactions with biological fluids.

With its good properties of biocompatibility and bioactivity hydroxyapatite (HA) is highly used as bone substitutes and as coatings on metallic prostheses. In order to improve the bioactive properties of HA, we have elaborated Zn2+ doped hydroxyapatite. Zn2+ ions substitute for Ca2+ cations in the HA structure and four Zn concentrations (Zn/Zn+Ca) were prepared at 0.5, 1, 2 and 5 at.%. To study physico-chemical reactions at the materials periphery, we immersed the bioceramics into biological fluids for intervals from 1 day to 20 days. The surface changes were studied at the nanometer scale by scanning transmission electron microscopy associated with energy dispersive X-ray spectroscopy. After 20 days of immersion, we observed the formation of a calcium-phosphate layer at the periphery of the HA doped with 5% zinc. This layer contains magnesium and its thickness was around 200 nm. Formation of this Ca-P-Mg layer represents the bioactive properties of 5% Zn-substituted hydroxyapatite. This biologically active layer improves the properties of HA and will permit a chemical bond between the ceramic and bone.

Body Fluids↗
PubMed1990

Alveolar ridge augmentation by osteoinduction in rats.

The purpose of this study was to evaluate bone substitutes for alveolar ridge augmentation by osteoinduction. Allogenic, demineralized, and lyophilized dentin and bone was tested for osteoinductive properties in order to establish an experimental model for further studies. Implantations were performed subperiosteally on the premaxilla and heterotopically in the abdominal muscles of rats. Light microscopic evaluations revealed that all allogenic, demineralized, and lyophilized dentin and bone implants induced new bone formation. No inflammatory or foreign body reactions were observed.

Abdominal Muscles↗
PubMed1999

Clinical evaluation of the treatment of class II furcation involvements with bioabsorbable barriers alone or associated with demineralized freeze-dried bone allografts.

BACKGROUND: Class II furcation lesions are a challenging scenario for periodontal therapy and a serious threat for tooth prognosis. Guided tissue regeneration represents a viable treatment option, but some aspects remain to be clarified as to the efficacy of bone substitutes used in GTR procedures. The clinical efficacy of demineralized freeze-dried bone allografts (DFDBA) for regenerative procedures is presently under scrutiny. METHODS: This study evaluated the adjunctive clinical effects of DFDBA associated with a bioabsorbable (polylactic acid) barrier membrane in the regenerative treatment of human Class II furcation lesions as compared to the same type of barrier alone. Twelve patients with bilateral Class II furcation defects on lower first molars participated in the study. In each patient, one tooth was randomly assigned to treatment consisting of open surgical debridement followed by the placement of DFDBA (GTR+DFDBA, or test group) and a bioabsorbable barrier, while the contralateral side received the same flap surgery followed by use of the bioabsorbable membrane alone (GTR, or control group). The clinical efficacy of the 2 treatment modalities was evaluated at 6 and 12 months postoperatively. Measurements included vertical probing depth (VPD), horizontal probing depth (HPD), clinical attachment level (CAL), amount of gingival recession (GR), and change in class of clinically detectable furcation involvement (FC). RESULTS: Both treatments yielded significant improvements for all clinical parameters between baseline and 6 and 12 months (P<0.05). The comparison between test and control groups revealed significantly greater reduction in HPD (P=0.01) and higher values of GR (P=0.008) for the test group. The mean gain in HPD for test sites was 2.3 mm, while it amounted to 1.7 mm for controls. A significantly greater proportion of test sites could be classified postoperatively as Class I defects compared to controls (91% versus 50%, respectively). CONCLUSIONS: The results of this study indicate that significant improvements from baseline occurred in VPD, HPD, CAL, and clinically detectable furcation involvement after the treatment of Class II furcation lesions with a bioabsorbable membrane with or without the adjunctive use of DFDBA. In addition, the placement of DFDBA in the furcation defect under the bioabsorbable membrane resulted in a greater mean reduction of horizontal probing depth when compared to the regenerative therapy alone.

Absorbable Implants↗
PubMed2004

Cements from nanocrystalline hydroxyapatite.

Calcium phosphate cements are used as bone substitute materials because they may be moulded to fill a void or defect in bone and are osteoconductive. Although apatite cements are stronger than brushite cements, they are potentially less resorbable in vivo. Brushite cements are three-component systems whereby phosphate ions and water react with a soluble calcium phosphate to form brushite (CaHPO4 x 2H2O). Previously reported brushite cement formulations set following the mixture of a calcium phosphate, such as beta-tricalcium phosphate (beta-TCP), with an acidic component such as H3PO4 or monocalcium phosphate monohydrate (MCPM). Due to its low solubility, hydroxyapatite (HA) is yet to be reported as a reactive component in calcium phosphate cement systems. Here we report a new cement system setting to form a matrix consisting predominantly of brushite following the mixture of phosphoric acid with nanocrystalline HA. As a result of the relative ease with which ionic substitutions may be made in apatite this route may offer a novel way to control cement composition or setting characteristics. Since kinetic solubility is dependent on particle size and precipitation temperature is known to affect precipitated HA crystal size, the phase composition and mechanical properties of cements made from HA precipitated at temperatures between 4 and 60 degrees C were investigated.

Bone Cements↗
PubMed2003

Cell-mediated bioresorption of sintered carbonate apatite in rabbits.

Bone apatite contains carbonate and is therefore not pure hydroxyapatite. We have successfully developed sintered carbonate apatite (CA) with a concentration of carbonate of 6 weight% and have evaluated its osteoconductive and bioresorption characteristics. Cylindrical porous sintered CA and sintered hydroxyapatite (HA) measuring 4 x 4 mm with a porosity of 20% were implanted into surgically-created bone defects in the knees of rabbits. The animals were killed after 1, 3, 6 and 12 months. The defects were evaluated by microfocus CT and histology. Bone growth into and around both materials increased. Newly-formed bone was placed in direct contact with both. Osteoclast-like cells resorbed only CA, and were coupled with osteoblasts. The porosity of sintered CA increased, indicating bioresorption, whereas that of sintered HA did not increase. Our findings indicate that sintered CA may be useful as a bioresorbable bone substitute.

Animals↗
PubMed2001

[Toxicity of glass ionomer cement].

BACKGROUND: The hybrid bone substitute ionomeric cement achieves a stable and durable space-free bond to adjacent bone during hardening. Clinical studies have evaluated the material differently: Fully hardened ionomeric cement showed in middle ear surgery, e.g. as an ossicular prosthesis, good biocompatibility with outstanding functional results. In a few cases, freshly mixed ionomeric cement led to severe complications after contact with CSF in skull base surgery. Therefore we intended to evaluate the influence of early fluid contact on the quality of cement and to define the interval for a safe application of the material, using a cell culture model. Further we intended to investigate whether combining cement with homologous and alloplastic materials influenced its quality. METHODS: 1) Ionomeric cement (Ionocem) test bodies were placed in Ringer's solution at different times after the mixing phase. 2) Ionomeric cement (Ionocem) test bodies were coated with different clinically used homologous and alloplastic materials during the setting and hardening phase. The concentrations of released cement-forming ions and the toxic effects on mouse fibroblasts within cell cultures were measured. RESULTS: Cytotoxic effects were observed when ionomeric cement was not carefully protected from fluid contact for the first two hours after mixing. This was due to forced fast elution of large amounts of cement-constituting fluoride ions and aluminium ions and to the development of acid valences and their interactions. A total hardening time of less than 25 min had an especially unfavourable influence on cell behaviour. Cell impairments could be reduced significantly by coating the 30-minute cured cement with PDS sheeting and significantly by covering it with viscous collagene. On the other hand, cement toxicity was intensified in part by combinations with some other coating materials. CONCLUSIONS: Ionomeric cement should be kept dry and protected from any fluid contact for at least 30 minutes after mixing. Contact with soft tissue should also be avoided for this time. With a hardening time of 30 minutes, the quality and biocompatibility of glass ionomeric cement could be substantially optimized by coating it with PDS sheeting. These results should be verified in animal experiments and clinical trials.

Animals↗
PubMed1994

Bone formation in coralline hydroxyapatite. Effects of pore size studied in rabbits.

We analyzed osseous reactions in the rabbit femoral condyle to coralline hydroxyapatite bone substitutes of various pore sizes by radiology and histology. The results were compared to bone repair of empty cavities and to integration of allografts. Spontaneous bone repair of the empty cavities took approximately 12 weeks, while integration of the cryopreserved allografts occurred after 9 weeks. However, no signs of new bone formation were found with the 200 microns pore size hydroxyapatite. In contrast, there was substantial production of bone within the 500 microns pore size implants at 12 and 26 weeks. Our results indicate that the pore size of the coralline hydroxyapatite influenced the development of bone in the implants in the cancellous bone bed of the rabbit femoral condyle. The results also show that spontaneous bone repair should be taken into consideration when the integration of implants is evaluated.

Animals↗
PubMed1990

[The regenerative ability of the iliac crest following spongiosa removal in man--induction by phosphate ceramics? I].

The starting point for the investigation of calcium phosphate ceramics is given by the bone regeneration, including osteoconduction, osteostimulation and osteoinduction. The amount of the autogeneic bone, which can be used for transplantation to induce the organo typical regeneration, is a small one. Calcium phosphate ceramics are used as bone substitute. The basic knowledge of clinical employment is summarized. A new model for investigation of bone regeneration is introduced. In part II the results will be discussed.

Biocompatible Materials↗
PubMed2001

[Experimental study of bone repair induced by cryopreserved allograft periosteum and fetal bone composition in bone defect].

OBJECTIVE: To investigate the repairing effect of transplantation of allogeneic fetal bone in combination with a covering cryopreserved periosteal allograft to bone defect. METHODS: Twenty Long-eared white male rabbits were chosen as experimental model of bilateral 12 mm combined bony and periosteal radial defect. Cryopreserved allograft periosteum with allogeneic fetal bone were implanted in the left defect as experimental side and fetal bone was simply transplanted in the right defect as control side. Bone repair process in the two groups were compared by macroscopy, microscopy, roentgenograms and the contents of calcium and phosphate in the defect area at 2, 4, 8 and 12 weeks after transplantation. RESULTS: There was significant statistic difference in the contents of calcium and phosphate between the experimental and control sides at 4, 8 and 12 weeks after transplantation (P < 0.05). With time passing by, the contents of calcium and phosphate have the increasing trends. In the experimental group, lamella bone was seen and medullary canal recanalized at 8 weeks postoperatively. The histological section showed the bone lacuna and lamella bone were formed. CONCLUSION: It suggests that allogeneic fetal bone in combination with a covering cryopreserved periosteal allograft can promote bone repair, and allogeneic fetal bone is excellent bone substitute.

Animals↗
PubMed2003

[Spinal instrumentation, source of progress, but also revealing pitfalls].

The second half of the XXo century and especially the last 30 years have been the source of a great improvement for surgical treatment of spinal pathology essentially in 3 directions:--First, for the patient himself and his comfort by suppression for most of the cases of any post operative external support thanks to the rigidity, security and strength of segmental fixation given by the hooks, screws and rods systems, as well for posterior as anterior instrumentation. In addition, these new techniques allow the patient to return quickly to standing and walking activity and subsequently the surgery for adult people increased dramatically especially for all kind of degenerative diseases and more and more extended spinal deformities.--The second major improvement came from the real and new understanding of the 3 dimensions for all the physiology and pathology of the spine leading to practical applications for the design and surgical strategies for correction. The exploding expansion of the era of computer technology brought a lot of help in such understanding as well as for the development of spinal instrumentation.--Finally the impressive development of medical imaging with CT scan and less and less invasive techniques like MRI allow a much better vision of spinal cord and roots (a major concern for the spinal surgeon). All this occurs also because simultaneous revolution occurred in the field of anesthesia and intensive care especially post operatively, but also because the big progress for monitoring of vital function as well as neurological monitoring during surgery. The consequence of that was an improvement for the results concerning the patient for functional quality of life as well as for cosmesis. The subsequent failures resulting of these improvements came from various fields even if we exclude infection or neurological complications more and more controlled now.--At the level of the indications because of these lack of post operative external immobilization, indication for cosmesis extend widely including adults. But also because these adult peoples are asking more and more for an active way of life including often sports. The indications for function also extend requiring more and more pre operative checking to limit the increase of the risk.--At the level of the pre operative strategy, most surgeons were establishing the strategy looking only on more or less close similar cases already done. In fact no personalized strategy done on biomechanical static and dynamic data of the patient as well as its connective and bone tissue proper qualities were really performed. It is why it is still now difficult to know pre operatively the behavior of the not fused area above and mainly below the instrumented area. Because the power of correction was very much improved with the new instruments, we can get some 3D imbalance immediately after or secondary acquired after such surgery as well from anterior or posterior devices. It is why we need pre operative simulation of surgery thanks to the computer.--At the level of surgery itself: it is not entered in the practical field any per operative 3D reliable measurement to know exactly the surgeon is doing because the maximum of reduction is not the optimum for many cases and this has to be quantified. The last thing is of course the difficulty to translate the lying position of the patient during surgery to the standing functional one. Some answers or perspectives for the future may come from:--The real pre operative simulation of the surgery (including levels of instrumentation amount of correction in 3D) according to the personalized values, stiffness, quality of soft tissues, weight, size, of the patient, localization and type of the deformity, etc.... Computer software already exists or are on the way to be expanded.--Per operative 3D control of what is doing the surgeon are also emerging with real time information in order to adjust the correction according to the pre op. simulation. In addition the noticed improvements on the biological field for fusion with bone activators like BMP, Hydroxyapatite, or bone substitutes like bio-active ceramics will probably help for fusion and decrease necessity of bone grafting. It is the same about disc regeneration which is on the way. Finally it is evident that the first steps already done for spinal surgery avoiding fusion will extend.--For children and growing spine, the challenge is major, but with memory metal instruments, laser precise destruction of abnormal growing structures as well as posterior flexible instrumentation avoiding stripping of the periosteum and leaving integrity of the disc and facet joints function, improvements are also on the way.--For adult and degenerative spinal deformities and pain, the development of spinal arthroplasty already done for the disc replacement will improve as well as for the posterior joints units where artificial ligaments experience will be replaced by real artificial joints still on experiment. In conclusion, some general biological medical questions are still waiting for answers:--Neurology and erect posture--Growth and degeneration--Malignancy (comprehension and control)--Pain and suffering. And of course what is the fact of the genetics for all of these problems: plenty of work for the future.

Adolescent↗
PubMedDate not supplied

Four-year follow-up of larger-diameter implants placed in fresh extraction sockets using a resorbable membrane or a resorbable alloplastic material.

PURPOSE: The aim of this randomized study was to evaluate and compare the long-term success rates of cylindric, screw-type titanium implants with a larger diameter (5.9 mm) that were placed in fresh extraction sockets in association with resorbable bone substitutes or a resorbable membrane. MATERIALS AND METHODS: Eighty-three partially edentulous adult patients, selected from among those treated in 1997 and 1998 at the San Raffaele Institute in whom 1 or more implants had been placed into fresh posterior mandibular or maxillary sockets, were included in the study. A total of 111 implants were placed, 36 in mandibles and 75 in maxillae. Fifty-six implants were placed in combination with resorbable hydroxyapatite (HA group) and 55 with a resorbable membrane (MR group). Intraoral radiographs and follow-up examinations, including verification of implant stability via the Periotest, were carried out at second-stage surgery 3, 6, 9, and 12 months later; and then annually up to 4 years after placement of the definitive restoration. The radiographic examination was conducted by means of a standardized procedure to verify osseointegration. RESULTS: There was 100% attendance at the follow-up examination after 4 years. At second-stage surgery, which was performed after 4 to 6 months' healing time, none of the implants showed any signs of mobility, peri-implantitis, or bone loss. Two implants failed in the MR group, one at 3 months and one at 9 months after placement; 1 implant failed in the HA group at 4 months after placement. After 4 years, the implant success rate was 97.3% (108 of 111 implants were considered successful). The success rate did not differ significantly between the HA group (98.2%) and the MR group (96.4%). DISCUSSION: The use of larger-diameter implants served to minimize the anatomic discrepancies that would have evolved when substituting a molar with a standard-diameter implant. According to the accepted criteria for success, the 5-year success rate should be at least 85%; therefore both methods may be considered satisfactory. CONCLUSION: Implants placed in combination with a resorbable allogeneic material or with a resorbable membrane provided predictable long-term results when restored with a fixed partial denture.

Absorbable Implants↗
PubMed1998

Epidural application of ionomeric cement implants. Experimental and clinical results.

During setting and hardening, the hybrid bone substitute ionomeric cement (Ionocem) achieves a stable and durable bond with the apatite of the adjacent bone without interpository soft tissue. Fluid contact during setting results in the release of aluminium ions which may reach critical levels as high as 3000 micrograms/l. On epidural application it is, therefore, essential to prevent cement constituents from gaining access to the intradural space. After the cement has hardened, the presence of aluminium is demonstrable in the adjacent bone to a maximum depth of 20 microns (EDX microanalysis). In rabbits, epidural placement of freshly mixed cement causes slight thickening of the dura. There is reason to believe that human dura, with a thickness 10 times greater, is impermeable to components of the cement. After epidural application of the freshly mixed cement in the frontobasal and laterobasal regions and at the skull cap and petrous apex, 76 patients in all have been followed for up to 6.5 years. During this period no complications have arisen and functional (and cosmetic) results are promising. The availability of preformed implants (Ionoroc, Ionocast) permitted the peridural placement of minimal quantities of freshly mixed cement. These implants were fixed to localized sites on the adjacent calvarial bone by use of Ionocem. Notwithstanding the stringent manufacturer guidelines, there have been reports in the literature that during the vulnerable stage of setting neurotoxic aluminium ions were released into the dural space with a fatal outcome in two cases. In view of potential intradural complications, such as may occur in case of dural leaks, it was considered that further application of the material adjacent to the dura was no longer warranted. The production of Ionocem was discontinued in May 1995.

Aluminum Silicates↗
PubMed2005

Predisposing conditions for retrograde peri-implantitis, and treatment suggestions.

BACKGROUND: Recent case reports introduced the term retrograde peri-implantitis as a lesion (radiolucency) around the most apical part of an osseointegrated implant. It develops within the first months after insertion. This retrospective study aimed to find predisposing conditions for such peri-apical lesions and to evaluate treatment strategies. METHODS: All single implants (426 in the upper, 113 in the lower jaw, all Brånemark system type) placed at the department of Periodontology of the University Hospital (Catholic University Leuven) were included in this retrospective evaluation to check the incidence of retrograde peri-implantitis. Eventual predisposing factors such as patient characteristics (age, medical history), recipient site (local bone quality and quantity, cause of tooth loss), periodontal and endodontic conditions of neighboring teeth, implant characteristics (length, surface characteristics), and surgical aspects (guided bone regeneration, osseous fenestration, or dehiscency) were considered. Moreover, implants with retrograde peri-implantitis were followed longitudinally to verify their treatment outcome by means of different parameters (Periotest values (PTV), marginal bone level, radiological size of peri-apical defect). RESULTS: Seven implants in the upper (1.6%) and 3 in the lower jaw (2.7%) showed retrograde peri-implantitis, before or at abutment connection. In comparison with successful implants, such peri-apical lesions occurred preferably at sites with a history of an obvious endodontic pathology of the extracted tooth to be replaced. The incidence of retrograde peri-implantitis was significantly higher (P<0.0001) for TiUnite implants when compared with the machined implants (8/80 vs. 2/459). The machined implant surface, however, showed a higher failure rate (6.8%) than the TiUnite implants (2.5%). Failures with machined surfaces preferably occurred at extraction sites of teeth with a history of endodontic pathology or sites adjacent to teeth with an obvious endodontic pathology. No other predisposing factors could be identified. A curettage of the peri-apical lesions and the use of a bone substitute material prevented further progression of such lesions in the upper jaw (implants maintained their marginal bone and low PTV scores). A treatment in the lower jaw was less successful. CONCLUSIONS: Within the limitations of a retrospective study, these results seem to indicate that retrograde peri-implantitis is provoked by remaining scar or granulomatous tissue at the recipient site: endodontic pathology of extracted tooth (scar tissue-impacted tooth) or possible endodontic pathology from a neighboring tooth.

Causality↗
PubMed2003

[Treatment of solitary bone cysts by intra-medullary nailing or steroid injection in children].

PURPOSE OF THE STUDY: Several methods are used to treat essential bone cysts in children: curettage with bone graft, simple drainage, steroid injection, intramedullary nailing. No one method is preferred by all. We compared two retrospective series of children with solitary bone cysts treated by steroid injection or intramedullary nailing. MATERIAL AND METHODS: Seventy-two cysts were treated by the same team: 54 by injection of methylprednisolone, and 18 by intramedullary nailing. Fifty cysts were disclosed by bone fracture. The others were revealed by pain or discovered fortuitously. Seventy-five percent of the patients were boys. The humerus was involved in two-thirds of the cases. Patient age ranged from 5 to 10 years. Intramedullary nailing was used for the femur in 10 cases and the humerus for 8. Steroid injections were given after cyst opacification using 160 mg per injection, total mean dose 800 mg (range 80-2400 mg). RESULTS: Cure was obtained at 4 years on the average, with no difference between the two series. Complications observed were transient or definitive and more severe in patients treated by steroid injections. Most of the complications were transient effects of steroid overdosage or limb length discrepancy: 7 shortenings (1-8 cm) for injected cysts (all in patients given > 100 mg methylprednisolone), compared with 2 shortenings<2 cm after intramedullary nailing. DISCUSSION: Steroid injections have been used for many years with variable results depending on the reported series. Cyst opacification before injection is recommended to identify anomalies which could compromise outcome. Strict compliance with the rules of steroid treatment is required to avoid complications, as observed in our patients, which are dose dependent. The percutaneous method is attractive but can be used with other products such as bone marrow or bone substitutes to optimize results. Intramedullary nailing has the advantage of providing immediate support of the damaged bone while allowing cyst drainage and evacuation of the lytic segments. This method should probably be preferred for weight-bearing segments whether the cyst is associated with fracture or not. For non-weight-bearing segments, the choice between percutaneous treatment, and the substance to use, and intramedullary nailing depends largely on bone quality.

Adolescent↗
PubMed2004

Bioresorbable composite bone paste using polysaccharide based nano hydroxyapatite.

Aim of this study concerns to the development of bioresorbable composite materials for bone repair and regeneration. Despite nano hydroxyapatite (HA) has wide range of medical applications, particles mobilization and slow resorbable nature limits its use in certain applications particularly, periodontal and alveolar ridge augmentation. To enhance its usage, we have prepared HA composite bone paste with a natural polysaccharide, chitosan, using wet chemical method at low temperature. The prepared composites were analyzed by various physicochemical methods and suggesting that the nano HA crystallites are well intact with the chitosan macromolecules. FT-IR results are indicating the existence of hydroxyl and amide groups in addition to the characteristic peaks of nano HA in the composite paste. The physical nature of paste form implies that it would be highly beneficial for the particle immobilization upon implantation. In vitro physiological stability and solubility of the composite was performed in phosphate buffered saline under physiological condition and found that the rate of resorbability of composite was quite higher than nano HA. These findings suggest that the HA/chitosan composites may have a great impact on human health care systems as bioresorbable bone substitute.

Absorbable Implants↗