Affordable implant prosthetics using a screwless implant system

Many dentists have been reluctant to place dental implants because they have found that most implants are costly and time-consuming to place and have long-term maintenance problems. Most of these problems are caused by using screws to connect the abutment to the implant, the crown to the abutment or both. The use of a screwless implant system and conventional prosthetics, the author contends, can make implant dentistry affordable, versatile and easy to incorporate into all general dental practices.     

Correcting for verification bias in studies of a diagnostic test's accuracy

Standard methods for assessing the accuracy of diagnostic tests require determination of true disease status for each study patient. In practice, some study patients might not have verified disease status. If the decision to verify a patient is influenced by the test result, analysis using only verified cases might lead to biased results, commonly known as verification bias. This paper reviews recent developments in bias-correction methods for studies on the accuracy of diagnostic tests.     

Proximal tibial osteotomy for osteoarthritis of the knee (author's transl)

One hundred and seventeen cases of osteoarthritis of the knee-joint, were treated with tibia osteotomy. The result of the different types of the osteotomy are discussed. The proximal tibial osteotomy without metal-fixation has the best results.     

Total knee replacement after failed tibial osteotomy: results of a matched-pair study

Sixty-three total knee replacements were performed after a failed tibial osteotomy. The goal of this study was to compare the perioperative problems and the outcome of this group of patients (study group) to a group of patients with primary arthroplasties matched for age, gender, length of follow-up, weight, and preoperative Charnley class. Operative problems were more frequently encountered in the study group, with 7 tibial tubercle elevations and 15 lateral retinaculum releases needed, whereas lateral retinaculum release was necessary for only 1 knee in the control group. Outcome was assessed using both the International Knee Society (IKS) scoring system and Hospital for Special Surgery (HSS) knee score. The follow-up period averaged 4.6 years. The IKS score of the control group was significantly higher, averaging 80.9 +/- 13.8, whereas it was 74.4 +/- 14.8 for the study group (P = .0001). Among the parameters included in the knee score, only pain was significantly different with the control group (P = .03). The IKS function score and the HSS score were not statistically different. Conversion of a failed tibial osteotomy is a technically demanding procedure. Careful preoperative planning is needed. Results, especially on pain, appeared to be inferior to those for primary arthroplasties.     

The clamp fixation method in cemented total knee arthroplasty. Dynamic experimental and radiographic studies of the tibial baseplate clamper

We describe 3 cases of Ochrobactrum anthropi meningitis following the implantation of pericardial allograft tissue to cover dural defects following craniotomy. Following an extensive epidemiologic investigation, the tissue allograft was found to have been contaminated with this unusual organism during the harvesting and processing of the tissue in the tissue bank. This organism was only susceptible to imipenem, tetracycline, gentamicin, and ciprofloxacin. The clinical presentation of these patients was subacute. Two of the patients developed osteomyelitis of the bone flap; while another developed a relapse of infection along a former ventriculoperitoneal shunt track 6 months after the initial infection. Appropriate clinical outcome was only observed after removal of tissue allograft implants, debridement of devitalized tissue and bone, removal of shunt devices, and prolonged courses of antibiotics. No deaths were observed.     

Full-arch implant framework casting accuracy: preliminary in vitro observation for in vivo testing

PURPOSE: Conventional techniques for implant metal framework fabrication produce error of a magnitude that is inconsistent with the passive-fit requirement for osseointegrated implants. To understand the correlation between prosthesis fit and the implant-tissue response, evaluation of the interface tissue reactions to customary levels of fit is required. The purpose of this study is to determine the accuracy of torch casting full arch frameworks using a high palladium alloy and a ringless phosphate-bonded investment technique. MATERIALS AND METHODS: Three different variables were considered relative to casting accuracy effect. The first variable, completeness of mold-fill, compared cast specimens where the entire sprue system was filled as part of the casting and cast specimens without the sprue system filled. The second variable, phosphate-bonded investment special liquid concentrations, compared groups of castings produced from 0%, 12%, 25%, and 50% special liquid. The third variable, investment mold shape, compared casting produced from a conventional ringless mold shape with a modified ringless mold shape where the investment in the same horizontal plane as the pattern was equal in thickness at the internal and external surfaces. Horizontal and vertical distances on the wax pattern and resulting framework were measured using a machinists microscope to determine casting error. Combined vertical and horizontal error was used for comparison between groups (one-way analysis of variance). RESULTS: No significant differences existed among the three groups compared (P > 0.05). The mean error comparison between the complete and incomplete mold-fill groups showed no statistical difference, while the incomplete fill group was found to be more porous. The mean error of all groups (0.130 mm) exceeded the recommended level of fit needed to satisfy the passive fit requirement by more than 10-fold. CONCLUSIONS: These results verify clinical observation and suggest that the use of conventional lost wax casting technique to cast one-piece full arch implant frameworks is both imprecise and inaccurate as judged against the passive fit requirement. The consequences of screw-fastening misfitting prostheses to osseointegrated implants is currently under investigation.     

Intra-articular tibial plateau stress fracture associated with osteoarthrosis and valgus knee deformity

Human capillary blood drawn by finger pricking was absorbed on Whatman no. 4 filter paper and tested for anti-Leishmania antibodies using the direct agglutination test (DAT). Over 1400 filter paper samples were collected from L. infantum endemic areas in northern Pakistan and compared with 569 serum samples obtained from the same area. Eleven filter paper samples (0.8%) gave positive results (antibody titre > or = 1:3200), compared with 8 serum samples (1.4%); the difference was not statistically significant (P = 0.35). The filter paper eluates compared well with their homologous sera, and were strongly correlated with respect to antibody titre (r = 0.7, P < 0.0001).     

Thoracoscopic surgery using voice controlled robot for spontaneous pneumothorax

Although there is abundant literature on the association of L-asparaginase and acute pancreatitis in patients undergoing chemotherapy, few studies have investigated the usefulness of pancreatic enzyme measurement in the early diagnosis of L-asparaginase-induced acute pancreatitis. We measured levels of serum pancreatic enzymes before, during, and after L-asparaginase therapy in nine children with acute lymphocytic leukaemia or non-Hodgkin lymphoma. Serum levels of amylase, pancreatic isoamylase, and lipase did not change between the 1st and 30th day of L-asparaginase administration. However, the serum trypsin and elastase- levels, 10 and 20 days after beginning L-asparaginase therapy, were significantly higher than those prior to therapy. CONCLUSION: L-asparaginase may induce subclinical pancreatitis and the estimation of serum trypsin and elastase-1 may be useful in the early diagnosis of L-asparaginase-induced acute pancreatitis.     

Psychophysical and speech perception studies: a case report on a binaural cochlear implant subject

Further improvements in speech perception for cochlear implant patients in quiet and in noise should be possible with speech processing strategies using binaural implants. For this reason, presented here is a series of initial psychophysical and speech perception studies on the authors' first binaural cochlear implant patient. For an approximate matching of the places of stimulation on the two sides, the patient usually reported a single percept when the two sides were simultaneously stimulated. Lateralization was strongly influenced by amplitude differences between the electrical stimuli on the two sides, but only weakly by interaural time delays. Speech testing, comparing monaural with binaural electrical stimulation, showed a binaural advantage particularly in noise.     

Hydroxyapatite coating versus cemented fixation of the tibial component in total knee arthroplasty: prospective randomized comparison of hydroxyapatite-coated and cemented tibial components with 5-year follow-up using radiostereometry

A mathematical model that characterizes the response of venous oxygenation to changes in cerebral blood flow (rCBF) and oxygen consumption has been previously presented. We use this model to examine the dampening phenomenon in functional MRI (fMRI) signals with rapidly alternating periodic stimulation bursts. Using a mass balance approach, the equations for an input-output model are derived and solved using Matlab (the Math Works Inc.). Changes in venous oxygenation are related to the results of fMRI experiments using progressively shorter periods of stimulation. An impulse-response function for the model is derived in an attempt to explore the source of the lag in cerebral hemodynamics. Increasing the frequency of stimulation bursts eventually produces a dampening in the fMRI signal. The dampening phenomenon in fMRI signals occurs with stimulation of high frequency on-off alternation. The dynamics of signal dampening, as well as the impulse-response function of a blood oxygen level-dependent model, lend strong indirect support to the hypothesis that blood oxygen level-dependent contrast at the level of the venous blood pool, rather than R1 inflow effects or changes in oxygenation at the level of the capillary bed, underlies the observed signal changes in fMRI.     

Reconstruction of compound tibial and soft tissue loss using a traction histogenesis technique

We used simultaneous bone and soft tissue transport for reconstruction of large compound tissue loss in the lower leg. We report the results and complications of a 12-patient series. The average age of the patients was 31.2 years (range 20 to 48 years). Seven patients had grade IIIB open tibial fractures, three had complications after grade II or IIIA, and two had an en-bloc resection of bone, muscle, and skin for a malignant bone tumor. Arteriography was routinely performed, and demonstrated at least one patent tibial artery. Every patient had normal sensibility of the sole. The first stage of the reconstruction was an aggressive excision of the all necrotic skin, muscle, and bone. The Ilizarov external fixator was applied and wires were secured under a tension of 100 kg, using a dynamometric tensioner. Cutaneous tissue loss was not replaced in 10 patients, when the bone was not exposed. A medial gastrocnemius flap was performed in two patients and lengthened with the bone. Corticotomy was performed 15 days after the first stage with careful respect for the periosteum. Distraction was initiated 15 days after the corticotomy. The average bone defect was 12.5 cm after initial excision. An average of 9 operative procedures and 18 months of treatment were required before bony union. The mean duration of bone transport was 6.5 months, and the mean duration of external fixation was 12 months. The final functional results were fair and only two patients returned to work. One patient had a below-knee amputation after 10 months of treatment.(ABSTRACT TRUNCATED AT 250 WORDS)     

Synovial immunohistochemical changes after high tibial osteotomy for osteoarthritis of the knee. Two-year prospective follow-up

PURPOSE: To evaluate a program designed to help high school students with depressive symptomology to effectively cope. DESIGN: Two-phase experimental study. METHODS: Rural high school students (N = 222), ages 14 through 19 years, were surveyed to identify teens with depressive symptomatology, identify stressful life events and coping styles of at-risk subjects, and evaluate a cognitive-behavioral group intervention to enhance students' coping and affect levels of depression. Students with depressive symptomatology were randomized into control (n = 18) or intervention (n = 23) groups. Intervention subjects were treated with a nurse-led, 8-week cognitive skills group, conducted at school. RESULTS: On posttesting, the intervention groups demonstrated reduced depressive symptoms in females and a wider range of coping compared with controls. CLINICAL IMPLICATIONS: School-based nurses are in an ideal position to provide assessment, referral, and intervention programs in the natural setting of the school. Results of this study indicate that such programs can be implemented successfully in schools and have the potential to promote mental health in teenagers.     

Repair of a deep digital tendon deficit in a horse using a polypropylene implant

A yearling horse was treated for a chronic wound with a 4 cm deficit in the deep digital tendon. The gap in the tendon was bridged with paired polypropylene braided implants designed for use as a ligament augmentation device. Uncomplicated healing and return to function occurred.     

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.     

Posterior tilting of the tibial component decreases femoral rollback in posterior-substituting knee replacement: a computer simulation study

The extensor tendons of the fingers and toes form part of the capsule of the interphalangeal joint and press against the proximal phalanx during flexion. Previous work on the fingers has shown that there is a "sesamoid" fibrocartilage on the deep surface of each tendon that labels immunohistochemically for a variety of glycosaminoglycans and collagens. However, we know little about the molecular composition of the tendon in the toes. This question is of special interest, because the mechanics of the interphalangeal joints differ in the upper and lower limbs-the toes balance the forefoot, distribute load during the gait cycle, and transmit the pull of larger muscles. This means that their extensor tendons are more often under higher tension than those in the fingers. Here, we report the presence of an equivalent fibrocartilage and compare its immunolabelling characteristics in all the toes. Six forefeet were removed from elderly cadavers, and the interphalangeal (IP) joints were fixed in 90% methanol. The extensor tendon and its enthesis were dissected out from the IP joint of the big toe and from the proximal interphalangeal (PIP) joint of all lesser toes, decalcified, cryosectioned, and immunolabelled with a panel of monoclonal and polyclonal antibodies for type I, II, III, and VI collagens; chondroitin 4 and 6 sulphates; and dermatan and keratan sulphate. Antibody binding was detected with the Vectastain ABC Elite avidin-biotin-peroxidase kit (Vector Laboratories, Burlingame, CA). The extensor tendon in all the toes had a metachromatic, sesamoid fibrocartilage on its deep surface that immunolabelled for all glycosaminoglycans and for type I, III, and VI collagens. Labelling for type II collagen was seen in the sesamoid fibrocartilage of all toes but was particularly characteristic of the 2nd through 5th toes. The immunolabelling patterns of the enthesis fibrocartilage were similar in all toes and to results reported previously for fingers. The normal occurrence of type II collagen in the sesamoid fibrocartilage of the 2nd through 5th toes is in contrast to our published data on the fingers. The finding can be related to the more constant loading of the tendon in the toes. The greater prominence of type II collagen in the sesamoid fibrocartilage of the 2nd through 5th toes could be related to a difference in joint position during walking between the 1st toe and the 2nd through 5th toes--the PIP joints of the latter are usually more flexed than the IP joint of the former.     

Patellofemoral complications following total knee arthroplasty. Correlation with implant design and patient risk factors

Grooming behavior of which the primary function appears to be the removal of lice on other (Tanaka and Takefushi [1993] Anthropological Science 101:187-193) was studied in Japanese maceques at Jigokudani Monkey Park, Japan, June 1990-July 1993. Several louse egg-handling techniques used during grooming were identified (with differences in efficiency) in a free-ranging group. In the low-ranking maternal lineages, the distribution of these techniques is quite homogeneous, suggesting social transmission with goal emulation (one form of social learning) based on maternal kin. However, there is considerable variation in the high-ranking matriline. The social system of dominance--the tendency of subordinates to groom more often than to be groomed--may result in oblique transmission of more effective techniques from low-ranking monkeys to some offspring of high-ranking females.     

The island posterior calf fasciocutaneous flap: an alternative to the gastrocnemius muscle for cover of knee and tibial defects

By repeatedly presenting an alien scent to territory-owning beavers, Castor canadensis, we tested two competing hypotheses about the function of scent marking: scent fence and scent matching. The scent-fence hypothesis predicts that territory owners should respond increasingly strongly over time towards a recurrent alien scent because of the ineffectiveness of previous responses. The scent-matching hypothesis predicts that the intensity of response should be the same or decrease because, without the presence of the intruding signaller coupled with the chemical signal, the presence of the scent itself does not advertise the ownership of a territory. The response level of resident beaver families was stable to strangers' anal gland secretions (AGSs) and decreased to strangers' castoreum during a period of 6 days. These results support the scent-matching hypothesis but not the scent-fence hypothesis. Copyright 1998 The Association for the Study of Animal Behaviour. Copyright 1998 The Association for the Study of Animal Behaviour.