The influence of directional preference on lateral patellar dislocation: a case report.

BACKGROUND: There is little consensus on the conservative management of lateral patellar dislocations (LPD). Mechanical diagnosis and therapy (MDT) is an established classification system in the spinal and extremity population. This case report describes the use of MDT in the management and classification of a patient with LPD. CASE DESCRIPTION: The patient was a 20-year-old female with a 3-month history of left knee pain precipitated by a lateral patellar dislocation. The patient described pain and a feeling of instability with standing and walking and limitations in work and recreational activities which involve lifting, squatting, and running. Based on the patient's response to repeated end range knee movements, the patient was found to have a directional preference (DP) for knee extension and instruction in performance of knee extension DP exercises was provided. OUTCOMES: The patient's knee examination and subsequent intervention included her responses to repeated end range knee movements. Her knee pain was abolished, and strength, function, and motion were fully restored in five visits. A minimal clinically important difference (MCID) was achieved on the Lower Extremity Functional Scale (LEFS). At discharge, the patient was able to independently manage symptoms and perform all work and recreational activities at a pre-injury level and these improvements were maintained at a 9-month follow-up. DISCUSSION: There are various management strategies for lateral patellar dislocation. This case demonstrated the use of classifying, subgrouping, and treating a patient with lateral patellar dislocation using the principle of DP. CONCLUSION: The patient's outcomes suggest that MDT may be used in the nonoperative management of people with LPD who present with a DP.

Connective tissue growth factor does not affect transforming growth factor-beta 1-induced Smad3 phosphorylation and T lymphocyte proliferation inhibition.

Transforming growth factor-beta 1 (TGF-beta(1)) is a key regulator of immune tolerance. TGF-beta(1) controls T lymphocyte activation and is involved in the immunosuppressive function and generation of regulatory T lymphocytes. Connective tissue growth factor (CTGF) has an essential role in the formation of connective tissue and blood vessels. CTGF expression is induced by TGF-beta(1) in several cell types and CTGF mediates several of the downstream actions of TGF-beta(1). Since little is known about the potential synergy between CTGF and TGF-beta(1) in T lymphocyte biology, the purpose of the present study was to determine whether CTGF can modulate TGF-beta(1)-mediated effects on human CD4+ T lymphocytes. Human recombinant CTGF was expressed in HEK293 cells. rCTGF was biologically active demonstrated by induction of proliferation in the endothelial cell line EA hy 926. rCTGF alone did not potentiate or diminish anti-CD3-induced CD4+ T lymphocyte proliferation and did not activate the Smad signaling pathway in CD4+ T lymphocytes. Furthermore, rCTGF did not attenuate TGF-beta(1)-mediated inhibition of CD4+ T lymphocyte proliferation and TGF-beta(1)-induced Smad signaling in CD4+ T lymphocytes. These results indicate that rCTGF had no detectable effects of its own on human CD4+ T lymphocytes and did not potentiate the effects of low amounts of TGF-beta(1) on human CD4+ T lymphocytes. Overall, these data support the hypothesis that CTGF does not act on CD4+ T lymphocytes.

Haemostatic agents used in periradicular surgery: an experimental study of their efficacy and tissue reactions.

AIM: To evaluate the haemostatic efficacy and the histologic tissue responses after the application of different haemostatic agents used in periradicular surgery. METHODOLOGY: The study was conducted in the calvarium of six rabbits. Standardized bone defects (diameter 4 mm) were trephined, and different haemostatic agents were applied and compared with control defects: bone wax (left for 10 min), Stasis (ferric sulphate, left for 5 s), Expasyl (aluminium chloride, left for 2 min and left permanently in situ), and a combination of Expasyl (2 min) and Stasis (5 s). The sites were photographed before the application and after the removal of the haemostatic agents. Three independent examiners judged the initial and final bleeding (on the photographs) using a bleeding score for each site and treatment. The results were compared using Wilcoxon's signed rank test. For the histologic analysis, three animals were killed after 3 weeks and three animals after 12 weeks. Transverse, nondecalcified sections were stained with combined basic fuchsin and toluidine blue for descriptive histology. RESULTS: The most efficient haemorrhage control was provided by Expasyl in combination with Stasis and by Expasyl alone, whereas bone wax had the weakest bleeding reduction effect. The histologic analysis after 3 weeks demonstrated an inflammatory and foreign body tissue response towards all haemostatic agents. At 12 weeks, this tissue response was less pronounced but still present in sites treated with bone wax or Expasyl. In general, the inflammatory tissue reactions were limited to the bone defects, and never extended into the surrounding tissues. CONCLUSIONS: Expasyl alone or in combination with Stasis appeared to be the most efficient of tested agents to control the bleeding within the bony defects created in a rabbit calvarium model.

Peri-implant inflammation defined by the implant-abutment interface.

An implant-abutment interface at the alveolar bone crest is associated with sustained peri-implant inflammation; however, whether magnitude of inflammation is proportionally dependent upon interface position remains unknown. This study compared the distribution and density of inflammatory cells surrounding implants with a supracrestal, crestal, or subcrestal implant-abutment interface. All implants developed a similar pattern of peri-implant inflammation: neutrophilic polymorphonuclear leukocytes (neutrophils) maximally accumulated at or immediately coronal to the interface. However, peri-implant neutrophil accrual increased progressively as the implant-abutment interface depth increased, i.e., subcrestal interfaces promoted a significantly greater maximum density of neutrophils than did supracrestal interfaces (10,512 +/- 691 vs. 2398 +/- 1077 neutrophils/mm(2)). Moreover, inflammatory cell accumulation below the original bone crest was significantly correlated with bone loss. Thus, the implant-abutment interface dictates the intensity and location of peri-implant inflammatory cell accumulation, a potential contributing component in the extent of implant-associated alveolar bone loss.

A procedure to define natural groundwater conditions of groundwater bodies in Germany.

Commissioned by Germany's Working Group of the Federal States on Water Problems (LAWA) the authors developed a procedure to define natural groundwater conditions from groundwater monitoring data. The distribution pattern of a specific groundwater parameter observed by a number of groundwater monitoring stations within a petrographically comparable groundwater typology is reproduced by two statistical distribution functions, representing the "natural" and "influenced" components. The range of natural groundwater concentrations is characterized by confidence intervals of the distribution function of the natural component. The applicability of the approach was established for four hydrochemically different groundwater typologies occurring throughout Germany. Based on groundwater monitoring data from 7920 groundwater monitoring stations, 15 different hydrochemical parameters were evaluated for each groundwater typology. For all investigated parameters the range of natural groundwater concentrations has been identified. According to the requirements of the EC Water Framework Directive (article 17) (WFD) this study is a basis for the German position to propose criteria for assessing a reference state for a "good groundwater chemical status".

Enhanced bone apposition to a chemically modified SLA titanium surface.

Increased surface roughness of dental implants has demonstrated greater bone apposition; however, the effect of modifying surface chemistry remains unknown. In the present study, we evaluated bone apposition to a modified sandblasted/acid-etched (modSLA) titanium surface, as compared with a standard SLA surface, during early stages of bone regeneration. Experimental implants were placed in miniature pigs, creating 2 circular bone defects. Test and control implants had the same topography, but differed in surface chemistry. We created the test surface by submerging the implant in an isotonic NaCl solution following acid-etching to avoid contamination with molecules from the atmosphere. Test implants demonstrated a significantly greater mean percentage of bone-implant contact as compared with controls at 2 (49.30 vs. 29.42%; p = 0.017) and 4 wks (81.91 vs. 66.57%; p = 0.011) of healing. At 8 wks, similar results were observed. It is concluded that the modSLA surface promoted enhanced bone apposition during early stages of bone regeneration.

Persistent acute inflammation at the implant-abutment interface.

The inflammatory response adjacent to implants has not been well-investigated and may influence peri-implant tissue levels. The purpose of this study was to assess, histomorphometrically, (1) the timing of abutment connection and (2) the influence of a microgap. Three implant designs were placed in the mandibles of dogs. Two-piece implants were placed at the alveolar crest and abutments connected either at initial surgery (non-submerged) or three months later (submerged). The third implant was one-piece. Adjacent interstitial tissues were analyzed. Both two-piece implants resulted in a peak of inflammatory cells approximately 0.50 mm coronal to the microgap and consisted primarily of neutrophilic polymorphonuclear leukocytes. For one-piece implants, no such peak was observed. Also, significantly greater bone loss was observed for both two-piece implants compared with one-piece implants. In summary, the absence of an implant-abutment interface (microgap) at the bone crest was associated with reduced peri-implant inflammatory cell accumulation and minimal bone loss.

Evaluation of a prototype trilayer membrane (PTLM) for lateral ridge augmentation: an experimental study in the canine mandible.

The objective of this animal study was to evaluate a biodegradable/bioresorbable prototype trilayer membrane (PTLM) consisting of two collagen layers and an internal polylactide layer for lateral ridge augmentation in conjunction with two different bone grafting materials: particulate autograft or deproteinized bovine bone mineral (DBBM). In four mongrel dogs, two lateral bone defects per side were created in the mandible. The four defects per dog were randomly subjected to the following grafting treatments 3 months later: 1. PTLM+DBBM, 2. PTLM+particulate autograft, 3. ePTFE membrane+DBBM, 4. ePTFE membrane+particulate autograft. After a healing period of 4 1/2 months, the dogs were sacrificed for histological and histomorphometrical analysis. Percentage calculations for areas showing bone regeneration within the former defect outline were 56.8% for PTLM+DBBM, 85.2% for PTLM+autograft, 52.3% for ePTFE+DBBM, and 96.9% for ePTFE+autograft (differences between autograft and DBBM sites were significant at P<0.01 to P<0.05). Measurements of ridge enlargement (horizontal bone gain) were also significantly better for autograft+ePTFE sites compared to the other three grafting treatments. Histology demonstrated for most PTLM sites a moderate infiltration of lymphocytes and plasma cells adjacent to empty spaces corresponding to polylactide fragments. In addition, these reactions appeared to provoke subsequent resorption of newly formed bone. No such findings were seen in ePTFE sites. The tested prototype membrane cannot be recommended for clinical application.

[Cementless socket fixation based on the "press-fit" concept in total hip joint arthroplasty]. / Zementfrei pfannenverankerung nach dem "Press-Fit-Konzept" bei der Totalprothesen-Arthroplastik der Hüfte.

PURPOSE OF THE STUDY: The key problem of implant fixation in THR is stress distribution, i.e. load transmission between bone and implant. The closer the load transfer is to the original physiological situation, the easier the adaptation of the periprosthetic bone to the new biomechanical conditions after implantation of the cup and the safer is its longlasting fixation. The aims of the studies were 1) to get information about the physiological load transfer in the normal hip joint, 2) to get information about the load transfer between acetabulum and acetabular sockets and vice versa, 3) to measure the periacetabular pelvic bone deformation as the stimulator of the remodelling process (third stage of osseointegration) in the normal hip joint and in hip joints fitted with different acetabular cups, 4) to study the morphological stages of osseointegration of a non-cemented press-fit cup and to compare the morphological structure of the periacetabular bone with the biomechanical data obtained by the in vitro studies and finally, 5) to compare the clinical and radiological outcome of follow-up studies of the senior author's "Press-Fit cup" with the theoretical hypotheses according to the experimental observations. MATERIAL AND METHODS: Load transfer between the acetabular bone and the femoral head on one side and press-fit cups has been determined by strain gauge measurements, finite element studies, pressure sensitive Fuji prescale films, CT-osteoabsorptiometry and telemetric measurements. Periacetabular deformation has been measured by Imetric Markers. Osseointegration of the senior author's press-fit cup and, thus, the remodelling process of the bony structures adjacent to the cup have been studied in autopsy specimens of THRs which have been in situ for several years. RESULTS: Load transfer measurements have shown that the main load in the original acetabulum as well as in the acetabulum fitted with a press-fit cup is transmitted to the periphery, especially to the acetabular cortical rim whereas the subchondral bone is exposed to lower, predominantly meridional (tension) stresses. Direct measurements of the periacetabular deformation under load revealed an increase of the peripheral press-fit with increasing stability of a (oversized) press-fit cup. Both the normal as well as the acetabulum fitted with a non-cemented cup deforms in a postero-medial direction. The histo-morphology of the periacetabular bone of autopsy specimens showed excellent bony in- and ongrowth of a porous titanium coating (SULMESH) and bone formation, especially at the periphery in zone 1 and 3 according to DeLee and Charnley. CONCLUSION: The studies have shown that the subchondral bone plate of the acetabulum has very little supportive function for non-cemented press-fit cups. For the preparation of the acetabulum it is, therefore, more important to ream the sclerotic subchondral bone until there is a well vascularized, well bleeding bone bed to facilitate osseointegration of a non-cemented acetabular socket than to preserve the subchondral bone plate as is the case in cement fixation. A non-cemented press-fit socket must transmit load predominantly to the cortical bone of the acetabular rim. Therefore, a too far medial positioning of the cup, and therefore loosing contact to the cortical rim, must be avoided under all circumstances. The clinical experience with acetabular revisions and with conversions of hip arthrodeses into a THR (where there is no subchondral bone at all) have shown the superiority of a well vascularized over a sclerotic (even mechanically stronger) bone bed. Furthermore, it has been shown that the additional use of screws for fixation of an acetabular cup is not only unnecessary but can be deleterious and causes complications including osteolysis and aseptic loosening.

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.

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.

Porous tricalcium phosphate and transforming growth factor used for anterior spine surgery.

Harvesting autologous bone graft from the iliac crest is associated with considerable secondary morbidity. Bone graft substitutes such as porous ceramics are increasingly used for spinal surgery. This paper presents the results of an animal study in which beta-tricalcium phosphate (beta-TCP) bone substitutes were used for anterior spinal surgery in sheep and baboons. The presented baboon study also investigated the effect of impregnating the ceramic material with transforming growth factor (TGF). In the first study, using the sheep model, a stand-alone instrumented anterior fusion was performed. The animals were randomized into three treatment groups: autologous bone, beta-TCP granules, and sham group. The results were analyzed biomechanically and histologically at three survival intervals: 8, 16 and 32 weeks. An additional animal group was added later, with ceramic pre-filled implants. In the second study, a baboon model was used to assess the osteointegration of a 15-mm-diameter porous beta-TCP block into the vertebral body. The experiment was partially motivated by a new surgical procedure proposed for local bone graft harvest. Three treatment groups were used: beta-TCP plug, beta-TCP plug impregnated with TGF-beta3, and a sham group with empty defect. The evaluation for all animals included computer tomograms at 3 and 6 months, as well as histology at 6 months. In the sheep model, the mechanical evaluation failed to demonstrate differences between treatment groups. This was because massive anterior bone bridges formed in almost all the animals, masking the effects of individual treatments. Histologically, beta-TCP was shown to be a good osteoconductor. While multiple signs of implant micromotion were documented, pre-filling the cages markedly improved the histological fusion outcomes. In the baboon study, the beta-TCP plugs were completely osteointegrated at 6 months. For the group that used ceramic plugs impregnated with TGF-beta3, no incremental advantage was seen as a result of this particular application. However, TGF-beta3 is a potent growth factor at a very low dose. Not only does it speed up the ceramic material resorption, but it is also responsible for massive regional new bone formation. More experiments are required to better understand the biological effects of this growth factor in relation to bone formation, and to be able to take clinical advantage of them.

Crestal bone changes around titanium implants: a methodologic study comparing linear radiographic with histometric measurements.

Generally, endosseous implants can be placed according to a nonsubmerged or a submerged technique and in 1-piece or 2-piece configurations. Recently, it has been shown that peri-implant crestal bone reactions differ significantly radiographically as well as histometrically under such conditions and are dependent on a rough/smooth implant border in 1-piece implants and on the location of a microgap (interface) between the implant and the abutment/restoration in 2-piece configurations. The purpose of this study was to evaluate whether standardized radiography as a noninvasive clinical diagnostic method correlates with peri-implant crestal bone levels as determined by histometric analysis. Fifty-nine implants were placed in edentulous mandibular areas of 5 foxhounds in a side-by-side comparison in both submerged and nonsubmerged techniques. Three months after implant placement, abutment connection was performed in the submerged implant sites. At 6 months, all animals were sacrificed, and evaluations of the first bone-to-implant contact (fBIC), determined on standardized periapical radiographs, were compared to similar analyses made from nondecalcified histology. It was shown that both techniques provide the same information (Pearson correlation coefficient = 0.993; P < .001). The precision of the radiographs was within 0.1 mm of the histometry in 73.4% of the evaluations, while the level of agreement fell to between 0.1 and 0.2 mm in 15.9% of the cases. These data demonstrate in an experimental study that standardized periapical radiography can evaluate crestal bone levels around implants clinically accurately (within 0.2 mm) in a high percentage (89%) of cases. These findings are significant because crestal bone levels can be determined using a noninvasive technique, and block sectioning or sacrifice of the animal subject is not required. In addition, longitudinal evaluations can be made accurately such that bone changes over various time periods can be assessed. Such analyses may prove beneficial when trying to distinguish physiologic changes from pathologic changes or when trying to determine causes and effects of bone changes around dental implants.

Incidence and indications for reintubation during postoperative care following orthotopic liver transplantation.

STUDY OBJECTIVE: To analyze the incidence and indications for reintubation during postoperative care following orthotopic liver transplantation (OLT). DESIGN: Retrospective chart review. SETTING: Large metropolitan teaching hospital. PATIENTS: 546 adult liver transplant recipients. MEASUREMENTS AND MAIN RESULTS: The medical charts of 546 patients who underwent OLT at our institution between January 1992 and September 1996 were reviewed for the incidence and indications of reintubation throughout primary hospitalization. Eighty-one of 546 patients (14.8%) required one or more episodes of reintubation after OLT. In the majority of cases, reintubation was performed for pulmonary complications (44.6%), followed by cerebral (19.1%) and surgical (14.5%) complications. Cardiac (9.1%) and peripheral neurologic (2.7%) complications were less frequent reasons for reintubation. Overall patient survival, according to the Kaplan-Meier estimates, was 89.9%, 87.5%, 86.5%, and 82.2% after 1, 2, 3, and 5 years, respectively. In patients with one or more episodes of reintubation, overall survival decreased to 62.5% after 1, 2, and 3 years, and to 56.4% after 5 years (p < 0.001). CONCLUSIONS: The main indications for reintubation after OLT were pulmonary, cerebral, and surgical complications. These reintubation events had a considerable influence on the patient's postoperative recovery, and were associated with a significantly higher rate of mortality, than for OLT patients who did not undo reintubation.

Lateral ridge augmentation and implant placement: an experimental study evaluating implant osseointegration in different augmentation materials in the canine mandible.

The present study investigated the osseointegration of dental implants with a titanium plasma-sprayed surface (TPS) in regenerated and native bone in an experimental dog study. Initially, lateral bone defects were created in the alveolar ridge on both sides of the mandible. Two months later, lateral ridge augmentation was performed with (1) autogenous corticocancellous block grafts, (2) autogenous corticocancellous block grafts and e-PTFE membrane, (3) tricalcium phosphate particles and e-PTFE membrane, or (4) canine-derived demineralized freeze-dried bone allograft particles and e-PTFE membrane. After 4 months, membranes were removed, and non-submerged titanium implants were placed in regenerated bone (test implants) and in native bone (control implants). Two months later, the animals were sacrificed and non-decalcified orofacial sections were evaluated histometrically. All implants demonstrated high percentages (59% to 75%) of bone-to-implant contact, with no significant differences across the various treatment groups. The different grafting techniques did not significantly influence the location of first bone-to-implant contact and the horizontal bone width at the most coronal bone level.

Lateral ridge augmentation using different bone fillers and barrier membrane application. A histologic and histomorphometric pilot study in the canine mandible.

Lateral ridge augmentation has become a standard treatment option to enhance the bone volume of deficient recipient sites prior to implant placement. In order to avoid harvesting an autograft and thereby eliminating additional surgical procedures and risks, bone grafting materials and substitutes are alternative filler materials to be used for ridge augmentation. Before clinical recommendations can be made, such materials must be extensively studied in experimental models simulating relevant clinical situations. The present pilot study was conducted in three dogs. Different grafting procedures were evaluated for augmentation of lateral, extended (8 x 10 x 14 mm) and chronic bone defects in the mandibular alveolar ridge. Experimental sites received tricalcium phosphate (TCP) granules or demineralized freeze-dried bone allograft (DFDBA) particles. Barrier membranes (ePTFE) were placed for graft protection. These approaches were compared to ridge augmentation using autogenous cortico-cancellous block grafts, either with or without ePTFE-membrane application. After a healing period of six months, the sites were analyzed histologically and histomorphometrically. Autografted sites with membrane protection showed excellent healing results with a well-preserved ridge profile, whereas non-protected block grafts underwent bucco-crestal resorption, clearly limiting the treatment outcome. The tested alloplastic (TCP) and allogenic (DFDBA) filler materials presented inconsistent findings with sometimes encapsulation of particles in connective tissue, thereby reducing the crestal bone width. The present pilot study supports the use of autografts with barrier membranes for lateral ridge augmentation of extended alveolar bone defects.

Postoperative tracheal extubation after orthotopic liver transplantation.

BACKGROUND: The duration of postoperative mechanical ventilation and its influence on pulmonary function in liver transplant recipients is still debated controversially. METHODS: We retrospectively analyzed the incidence of immediate tracheal extubation, prolonged mechanical ventilation (>24 h following surgery), and episodes of reintubation in 546 patients who underwent orthotopic liver transplantation (OLT) at our institution. RESULTS: Immediate tracheal extubation in the operating theater was achieved in 18.7% of patients, and prolonged mechanical ventilation was required by 11.2% of patients. In these, median time of extubation was 49.5 h, whereas the remaining 70.1% of patients required ventilation support for a median 5 h after OLT. As risk factors for prolonged mechanical ventilation we identified the indications of acute liver failure and retransplantation, as well as factors such as mechanical ventilation prior to OLT, massive intraoperative bleeding, and severe reperfusion injury of the liver graft. The incidence of reintubation was 8.8% in patients who were immediately extubated following surgery, and 13.1% in patients who underwent extubation within 24 h. The incidence was significantly increased in patients requiring prolonged mechanical ventilation (36.1%). CONCLUSIONS: Immediate tracheal extubation was safe and well tolerated. The incidence of reintubation was not increased when compared to patients in whom extubation succeeded later. However, special attention should be given to transplant recipients presenting in reduced clinical condition at the time of OLT, undergoing complicated surgery, or receiving liver allografts with severe reperfusion injury because of an increased risk for prolonged mechanical ventilation.

Periodontal regeneration with an autogenous bone-Bio-Oss composite graft and a Bio-Gide membrane.

This study evaluated the clinical, radiographic, and histologic response to the composite use of Bio-Oss porous bone mineral and autogenous bone in combination with a Bio-Gide bilayer collagen membrane to achieve regeneration when treating human periodontal bone defects. Preoperative recordings for four treatment areas included radiographs, clinical probing depths, and attachment levels; these recordings were repeated at 9 months. Histologic evaluation revealed new cementum with inserting collagen fibers and new bone formation on the surface of both types of graft materials. This grafting combination not only compared favorably with the previous use of Bio-Oss and Bio-Gide, but exceeded that result with almost complete periodontal regeneration. This human histologic study demonstrates that autogenous bone in combination with porous bone mineral matrix, together with the Bio-Gide collagen membrane, has the capacity to stimulate substantial new bone and cementum formation with Sharpey's fiber attachment.

Crestal bone changes around titanium implants. A histometric evaluation of unloaded non-submerged and submerged implants in the canine mandible.

BACKGROUND: Today, implants are placed using both non-submerged and submerged approaches, and in 1- and 2-piece configurations. Previous work has demonstrated that peri-implant crestal bone reactions differ radiographically under such conditions and are dependent on a rough/smooth implant border in 1-piece implants and on the location of the interface (microgap) between the implant and abutment/restoration in 2-piece configurations. The purpose of this investigation was to examine histometrically crestal bone changes around unloaded non-submerged and submerged 1- and 2-piece titanium implants in a side-by-side comparison. METHODS: A total of 59 titanium implants were randomly placed in edentulous mandibular areas of 5 foxhounds, forming 6 different implant subgroups (types A-F). In general, all implants had a relatively smooth, machined coronal portion as well as a rough, sandblasted and acid-etched (SLA) apical portion. Implant types A-C were placed in a non-submerged approach, while types D-F were inserted in a submerged fashion. Type A and B implants were 1-piece implants with the rough/smooth border (r/s) at the alveolar crest (type A) or 1.0 mm below (type B). Type C implants had an abutment placed at the time of surgery with the interface located at the bone crest level. In the submerged group, types D-F, the interface was located either at the bone crest level (type D), 1 mm above (type E), or 1 mm below (type F). Three months after implant placement, abutment connection was performed in the submerged implant groups. At 6 months, all animals were sacrificed. Non-decalcified histology was analyzed by evaluating peri-implant crestal bone levels. RESULTS: For types A and B, mean crestal bone levels were located adjacent (within 0.20 mm) to the rough/smooth border (r/s). For type C implants, the mean distance (+/- standard deviation) between the interface and the crestal bone level was 1.68 mm (+/- 0.19 mm) with an r/s border to first bone-to-implant contact (fBIC) of 0.39 mm (+/- 0.23 mm); for type D, 1.57 mm (+/- 0.22 mm) with an r/s border to fBIC of 0.28 mm (+/- 0.21 mm); for type E, 2.64 mm (+/- 0.24 mm) with an r/s border to fBIC of 0.06 mm (+/- 0.27 mm); and for type F, 1.25 mm (+/- 0.40 mm) with an r/s border to fBIC of 0.89 mm (+/- 0.41 mm). CONCLUSIONS: The location of a rough/smooth border on the surface of non-submerged 1-piece implants placed at the bone crest level or 1 mm below, respectively, determines the level of the fBIC. In all 2-piece implants, however, the location of the interface (microgap), when located at or below the alveolar crest, determines the amount of crestal bone resorption. If the same interface is located 1 mm coronal to the alveolar crest, the fBIC is located at the r/s border. These findings, as evaluated by non-decalcified histology under unloaded conditions, demonstrate that crestal bone changes occur during the early phase of healing after implant placement. Furthermore, these changes are dependent on the surface characteristics of the implant and the presence/absence as well as the location of an interface (microgap). Crestal bone changes were not dependent on the surgical technique (submerged or non-submerged).