Investigation of the wear of prefabricated attachments--an in vitro study of retention forces and fitting tolerances

OBJECTIVE

To quantify wear processes by measuring the retention force changes and the fitting tolerance at different prefabricated attachment systems to estimate the wear constancy and applicability in clinical practice.

METHOD AND MATERIALS

Seven prefabricated attachment systems (Dalbo-Classic, Dalbo-PLUS, Dalbo-Z, Mini-Gerber-PLUS, Stufenexzenter, SpharoLock, and Degussa-Kugelankersystem) with different construction and alloy composition were tested. Twenty samples of each system were subjected to 10,000 insertion-separation cycles in a wear simulator with a periodontium-simulating specimen holder. The simulator was designed to record the force needed to insert and to separate the attachment and the distance moved during the insertion and separation cycles.

RESULTS

All types of anchors showed wear that led to a loss or to an increase in retention force at the beginning of the wear simulation. Anchors with a plastic retention insert showed the slightest changes in retention force. The wear does not have an effect on the fitting tolerance.

CONCLUSION

Anchor systems that possess an adjustable matrix should be preferred. They allow decreasing or increasing the retention force of an anchor if this force is changed by wear. There is no risk of a loss of support if forces in occlusal direction are exerted because there is no clinically relevant change in the fitting tolerance.

Tactile sensibility of single-tooth implants and natural teeth

AIM

The purpose of this randomized split-mouth clinical trial was to determine the active tactile sensibility between single-tooth implants and opposing natural teeth and to compare it with the tactile sensibility of pairs of natural teeth on the contralateral side in the same mouth (intraindividual comparison).

MATERIAL AND METHODS

The hypothesis was that the active tactile sensibilities of the implant side and control side are equivalent. Sixty two subjects (n=36 from Bonn, n=26 from Bern) with single-tooth implants (22 anterior and 40 posterior dental implants) were asked to bite on narrow copper foil strips varying in thickness (5-200 microm) and to decide whether or not they were able to identify a foreign body between their teeth. Active tactile sensibility was defined as the 50% threshold of correct answers estimated by means of the Weibull distribution.

RESULTS

The results obtained for the interocclusal perception sensibility differed between subjects far more than they differed between natural teeth and implants in the same individual [implant/natural tooth: 16.7+/-11.3 microm (0.6-53.1 microm); natural tooth/natural tooth: 14.3+/-10.6 microm (0.5-68.2 microm)]. The intraindividual differences only amounted to a mean value of 2.4+/-9.4 microm (-15.1 to 27.5 microm). The result of our statistical calculations showed that the active tactile sensibility of single-tooth implants, both in the anterior and posterior region of the mouth, in combination with a natural opposing tooth is similar to that of pairs of opposing natural teeth (double t-test, equivalence margin: +/-8 microm, P<0.001, power >80%). Hence, the implants could be integrated in the stomatognathic control circuit.

Podocalyxin-like protein 1 expression in primary hepatic tumours and tumour-like lesions

AIMS

The differential diagnosis of benign hepatic lesions and well-differentiated hepatocellular carcinomas can be a challenge, especially in small biopsy specimens. Recently, novel proteins expressed by the neovasculature in hepatocellular carcinoma (HCC) have been identified. The aim of this study was to compare the expression of podocalyxin-like protein 1 (PODXL1), a CD34-related sialomucin, in HCC and benign liver tumours or tumour-like lesions.

METHODS AND RESULTS

Vascular marker expression was examined using tissue microarrays as well as standard paraffin sections from formalin fixed paraffin-embedded liver tissue samples. Expression of PODXL1 was compared with anti-CD34, CD31 and von Willebrand factor VIII staining by immunohistochemistry. PODXL1 is expressed in tumour-associated microvasculature endothelial cells in HCC, as well as in capillarized sinusoidal endothelium of focal nodular hyperplasia (FNH) and hepatic adenoma. Expression in cirrhotic nodules correlates with CD34 and highlights endothelium in the inflow area. In dysplastic nodules CD34 and PODXL1 are not or only focally expressed.

CONCLUSIONS

Expression patterns of CD34 and PODXL1 are almost identical in primary hepatic tumours and tumour-like lesions. The presence of CD34+ and PODXL1+ sinusoidal endothelial cells aids in the diagnosis of HCC. Sinusoidal expression of PODXL1 is also seen in a less diffuse pattern in FNH and adenoma.

Achilles tendon lengthening for ankle equinus deformity in hemophiliacs: 23 patients followed for 1-24 years

BACKGROUND

Bleeding in the calf or ankle joint may lead to ankle equinus deformity, particularly in childhood and during adolescence. We assessed the long-term functional and radiographic results after Achilles tendon lengthening for ankle equinus deformity in hemophiliacs.

PATIENTS AND METHODS

Between 1975 and 1986, 30 hemophilic patients with pes equinus were surgically managed by Achilles tendon lengthening. Of these, 23 were followed up prospectively twice a year for an average of 13 (1-24) years. The mean age at operation was 29 (12-46) years. The clinical results were documented according to the score of the Advisory Committee of the World Federation of Hemophilia (WFH), while radio-graphs were evaluated using the Pettersson score. On average, preoperative ankle equinus deformity was 21 (5-55) degrees. Mean range of motion was 21 (5-42) degrees prior to surgery.

RESULTS

At the first postoperative examination 1 year after surgery, 21/23 cases were improved, and 9/21 reached dorsiflexion to at least neutral position. At the last follow-up, ankle equinus deformity was 10 (4-20) degrees on average. 20/23 patients still showed significant improvement compared to their condition before surgery. 7 patients still had complete correction of the equinus deformity, while mean range of motion decreased constantly over the observation period. The clinical score was significantly improved 1 year after surgery and diminished only slightly afterwards. Radio-graphic outcome deteriorated, with scores rising from 4.3 (1-10) points preoperatively to 7.3 (3-12) points at last follow-up.

INTERPRETATION

Most patients treated for hemophilic pes equinus by Achilles tendon lengthening experienced long-term benefit concerning the equinus deformity, but gradually lost overall movement of the ankle joint. Progression of the ankle arthropathy cannot be hindered.

MRI in the diagnosis of sporadic Creutzfeldt-Jakob disease: a study on inter-observer agreement

According to the current WHO criteria, technical investigations included in the clinical diagnosis of sporadic Creutzfeldt-Jakob disease (sCJD) are electroencephalogram (EEG) and CSF-analysis for 14-3-3 proteins. MRI is not a criterion for the diagnosis of sCJD, although typical changes have been described. We investigated the reliability of MRI in the sCJD diagnosis, evaluated MRI sequences and compared MRI with EEG and 14-3-3. This study includes 193 consecutive suspected sCJD patients who had been referred to the German CJD Surveillance Unit from 2001 to 2003. Three observers independently analysed MRI scans, blinded to clinical data. MRI was rated as 'typical for sCJD' if increased signal intensity was detected in the caudate nucleus and putamen. We analysed 442 MRI scans [184 T2-weighted sequences, 132 fluid attenuated inversion recovery (FLAIR) sequences, 75 diffusion-weighted sequences and 51 proton-density weighted sequences]. Inter-observer agreement was 123 of 193 patients or 63.7% (overall kappa = 0.53). Sensitivity of MRI in clinically probable or autopsy-proven sCJD was 59.7% for Observer 1, 58.3% for Observer 2 and 70.8% for Observer 3; specificity was high (84.2, 89.5 and 81.6%, respectively). Diffusion-weighted sequences best showed the pathologic changes, followed by FLAIR. Periodic sharp and slow wave complexes were detected in the EEG in 32% (sensitivity), the 14-3-3 proteins in CSF were elevated in 91%. We conclude that the detection of hyperintense basal ganglia in MRI helps to improve the clinical diagnosis, and therefore, we propose to incorporate MRI in the diagnostic criteria for sCJD.

The efficacy of dietary intervention on urinary risk factors for stone formation in recurrent calcium oxalate stone patients

PURPOSE

Nutrition is suggested to be the major environmental risk factor in idiopathic calcium oxalate stone disease. The study was designed to evaluate the effect of dietary intervention on urinary risk factors for recurrence in calcium oxalate stone formers.

MATERIALS AND METHODS

A total of 76 men and 31 women with idiopathic calcium oxalate stone disease collected 24-hour urine on their habitual, self-selected diets and after 7 days on a balanced standardized diet according to the recommendations for calcium oxalate stone formers.

RESULTS

On the usual diet, a urine volume of less than 2.0 l per 24 hours was present in 57.9%, hypercalciuria in 25.2%, hypomagnesuria in 18.7%, hyperoxaluria in 14.0%, hyperuricosuria in 41.3% and hypocitraturia in 57.0% of patients. The frequency of metabolic abnormalities and the risk of calcium oxalate stone formation decreased significantly on the ingestion of the balanced diet, due to the significant increase in urinary volume, pH and citrate excretion and the significant decrease in urinary calcium and uric acid excretion. No change occurred in urinary oxalate and magnesium excretion.

CONCLUSIONS

The evaluation of urinary risk profiles of the patients on their usual dietary habits revealed a high risk for calcium oxalate stone formation. A low fluid intake and an increased intake of protein and alcohol were identified as the most important dietary risk factors. The shift to a nutritionally balanced diet according to the recommendations for calcium oxalate stone formers significantly reduced the stone forming potential.

The role of overweight and obesity in calcium oxalate stone formation

OBJECTIVE

The aim of the study was to assess the influence of overweight and obesity on the risk of calcium oxalate stone formation.

RESEARCH METHODS AND PROCEDURES

BMI, 24-hour urine, and serum parameters were evaluated in idiopathic calcium oxalate stone formers (363 men and 164 women) without medical or dietetic pretreatment.

RESULTS

Overweight and obesity were present in 59.2% of the men and in 43.9% of the women in the study population. Multiple linear regression analysis revealed a significant positive relationship between BMI and urinary uric acid, sodium, ammonium, and phosphate excretion and an inverse correlation between BMI and urinary pH in both men and women, whereas BMI was associated with urinary oxalate excretion only among women and with urinary calcium excretion only among men. Serum uric acid and creatinine concentrations were correlated with BMI in both genders. Because no association was established between BMI and urinary volume, magnesium, and citrate excretion, inhibitors of calcium oxalate stone formation, the risk of stone formation increased significantly with increasing BMI among both men and women with urolithiasis (p = 0.015). The risk of calcium oxalate stone formation, median number of stone episodes, and frequency of diet-related diseases were highest in overweight and obese men.

DISCUSSION

Overweight and obesity are strongly associated with an elevated risk of stone formation in both genders due to an increased urinary excretion of promoters but not inhibitors of calcium oxalate stone formation. Overweight and obese men are more prone to stone formation than overweight women.

Dietary risk factors for hyperoxaluria in calcium oxalate stone formers

BACKGROUND

Hyperoxaluria is a major predisposing factor in calcium oxalate urolithiasis. The aim of the present study was to clarify the role of dietary oxalate in urinary oxalate excretion and to assess dietary risk factors for hyperoxaluria in calcium oxalate stone patients.

METHODS

Dietary intakes of 186 calcium oxalate stone formers, 93 with hyperoxaluria (>or=0.5 mmol/day) and 93 with normal oxalate excretion (<0.4 mmol/day), were assessed by a 24-hour weighed dietary record. Each subject collected 24-hour urine during the completion of the food record. Oxalate content of foods was measured by a recently developed analytical method.

RESULTS

The mean daily intakes of energy, total protein, fat and carbohydrates were similar in both groups. The diets of the patients with hyperoxaluria were estimated to contain 130 mg/day oxalate and 812 mg/day calcium as compared to 101 mg/day oxalate and 845 mg/day calcium among patients without hyperoxaluria. These differences were not significant. The mean daily intakes of water (in food and beverages), magnesium, potassium, dietary fiber and ascorbic acid were greater in patients with hyperoxaluria than in stone formers with normal oxalate excretion. Multiple logistic regression analysis revealed that urinary oxalate excretion was significantly associated with dietary ascorbate and fluid intake, and inversely related to calcium intake. Differences of estimated diet composition of both groups corresponded to differences in urinary parameters.

CONCLUSIONS

These findings suggest that hyperoxaluria predominantly results from increased endogenous production and from intestinal hyperabsorption of oxalate, partly caused by an insufficient supply or low availability of calcium for complexation with oxalate in the intestinal lumen.

[Value of sonography after rotator cuff repair: a comparison with MRI and clinical results]

AIM

How well do ultrasound- and MRI-results after rotator cuff reconstruction correlate with postoperative clinical findings?

METHODS

Ultrasound- and MR-imaging of the afflicted shoulder on 40 patients who were surgically managed for isolated tear of the tendon of supraspinatus was performed at least 24 months after intervention. Patients were also clinically assessed. Based on the clinical result, sensitivity and specificity for the two imaging procedures was determined.

RESULTS

Only 11 (27.5%) patients had a completely inconspicuous ultrasonography. By ignoring the sonographic parameter "echogenicity" this number was raised to 29 (72.5%) patients. Without the above mentioned parameter ultrasonography demonstrated a good specificity (90.3%) yet a poor sensitivity (33.3%). Incorporation of "echogenicity" markedly weakened both values. MR-imaging showed an intact cuff in 32 (80%) patients, 5 (12.5%) had signs for a partial tear and in 3 (7.5%) a recurrent tear was diagnosed. Based on the clinical result, MR-imaging showed sufficient specificity (87.1%), yet also a poor sensitivity (44.4%).

CONCLUSION

After rotator cuff repair MRI- and ultrasound-findings frequently stand in distinct discrepancy to clinical results. Based on clinical findings, postoperative MR-imaging shows a slightly higher sensitivity than ultrasonography. Despite this, both radiographic methods do not allow deductions concerning the clinical outcome. The postoperative shoulder-scan and MRI should therefore be interpreted with utmost care. Symptoms and functional results are of high clinical relevance in the assessment of the postoperative shoulder.

Prospective Study on the Efficacy of a Selective Treatment and Risk Factors for Relapse in Recurrent Calcium Oxalate Stone Patients

OBJECTIVE

The present study was performed to examine the efficacy of a selective treatment according to the guidelines for the prevention of recurrence in calcium oxalate stone patients and to assess risk factors for stone recurrence.

METHODS

To investigate the effect of specific diagnostic and therapeutic measures, 134 recurrent calcium oxalate stone formers participated in a prospective study for two years with regular follow-ups of at least every six months. Depending on the results of analysis of 24-hour urine, nutrition record and metabolic situation, selective recommendations were given concerning diet and medication.

RESULTS

Throughout the follow-up period, 57 (43%) of the patients experienced relapses. In recurrence-free patients, the significant increase in urinary volume, as well as urinary pH, potassium and citrate excretion, three indexes of compliance with alkalization, resulted in a significant decrease in the calculated risk of calcium oxalate stone formation. In patients with recurrences during follow-up, the relative supersaturation with calcium oxalate increased significantly, mainly due to the significant rise in urinary oxalate excretion exceeding the significant increases in urinary volume, pH, potassium and citrate excretion. Multiple logistic regression analysis revealed previous ESWL treatment and a history of multiple stones as independent predictors of the risk for recurrence.

CONCLUSIONS

The results indicate that compliance with drinking advice and alkalization therapy was highest among both, patients with and without recurrences, compared with all other therapeutic measures. The increase in oxalate excretion is identified as the major urinary risk factor for relapse during follow-up in recurrent calcium oxalate stone disease.

Dietary risk factors for hyperoxaluria in calcium oxalate stone formers

BACKGROUND

Hyperoxaluria is a major predisposing factor in calcium oxalate urolithiasis. The aim of the present study was to clarify the role of dietary oxalate in urinary oxalate excretion and to assess dietary risk factors for hyperoxaluria in calcium oxalate stone patients.

METHODS

Dietary intakes of 186 calcium oxalate stone formers, 93 with hyperoxaluria (>or=0.5 mmol/day) and 93 with normal oxalate excretion (<0.4 mmol/day), were assessed by a 24-hour weighed dietary record. Each subject collected 24-hour urine during the completion of the food record. Oxalate content of foods was measured by a recently developed analytical method.

RESULTS

The mean daily intakes of energy, total protein, fat and carbohydrates were similar in both groups. The diets of the patients with hyperoxaluria were estimated to contain 130 mg/day oxalate and 812 mg/day calcium as compared to 101 mg/day oxalate and 845 mg/day calcium among patients without hyperoxaluria. These differences were not significant. The mean daily intakes of water (in food and beverages), magnesium, potassium, dietary fiber and ascorbic acid were greater in patients with hyperoxaluria than in stone formers with normal oxalate excretion. Multiple logistic regression analysis revealed that urinary oxalate excretion was significantly associated with dietary ascorbate and fluid intake, and inversely related to calcium intake. Differences of estimated diet composition of both groups corresponded to differences in urinary parameters.

CONCLUSIONS

These findings suggest that hyperoxaluria predominantly results from increased endogenous production and from intestinal hyperabsorption of oxalate, partly caused by an insufficient supply or low availability of calcium for complexation with oxalate in the intestinal lumen.

Long-term follow-up after osteotomy for haemophilic arthropathy of the knee

In this study the long-term value of corrective osteotomy around the knee was evaluated by means of clinical and radiographic parameters. Between 1974 and 1984 we performed 52 corrective osteotomies in the vicinity of the knee on patients affected by haemophilic arthropathy. Forty-two patients (45 osteotomies) were adequately followed-up at an average 11.6 years postoperatively. Using the clinical score of the Advisory Committee of the World Federation of Haemophilia, 38 patients showed a postoperative improvement, five remained clinically unchanged and two showed deterioration. Range of motion of the knee joint did not significantly improve postoperatively. The radiographic Pettersson score showed only a marginal decrease by an average 0.003 points at the time of follow-up. Only one patient needed subsequent joint replacement of both knees, on the left side 13 years after osteotomy and on the right side 8 years after osteotomy. Even in cases of marked radiographic joint destruction, corrective osteotomy shows acceptable long-term clinical results, underlining the feasibility of this management option in the treatment of haemophilic arthropathy of the knee. Although moderate cartilage degenerations in the femoropatellar complex and in the contralateral compartment can be tolerated, this therapy should primarily be contemplated for those patients where damage is unicompartmental and a corresponding axial deviation is found. Particularly the younger patient can benefit from this treatment option in that joint replacement may possibly wholly be avoided or at least postponed to a later stage of life.

Omega-3 fatty acids and low carbohydrate diet for maintenance of remission in Crohn's disease. A randomized controlled multicenter trial. Study Group Members (German Crohn's Disease Study Group)

BACKGROUND

There is no established therapy for maintaining remission in patients with Crohn's disease. Following different suggestions from the literature, two potential interventions for maintaining remission were tested against placebo, using either 5 g/day of a highly concentrated omega-3 fatty acid compound or a carbohydrate-reduced diet (84 g/day).

METHODS

A total of 204 patients were recruited after they had had an acute relapse. After remission (CDAI < or = 150) was attained with steroid therapy, patients were randomized to receive either omega-3 fatty acids (n = 70), placebo (n = 65), or diet (n = 69). Low-dose prednisolone was given to all patients for the first 8 weeks of intervention. CDAI and an acute-phase protein (CRP) were used as criteria for a relapse.

RESULTS

The proportion of patients without relapse within a year were similar in the placebo and active treatment group (intention-to-treat analysis: placebo, 30%; active treatment, 30%; protocol-adhering patients, 29% versus 28%). Patients did gain benefit (53%; p = 0.023) for as long as they maintained the diet. However, intention-to-treat analysis (diet group, 40%) did not show a noticeable difference when compared with placebo.

CONCLUSIONS

Omega-3 fatty acids did not show an effect on extending the remission in Crohn's disease. For the diet patients the question remains whether the noncompliant patients dropped out early because they sensed a relapse approaching or whether their condition deteriorated because they failed to comply with the diet.

Functional health status in male patients without restenosis following successful PTCA

In a prospective pilot study, subjective and objective parameters of the health status were assessed in 148 male patients (mean age 56 +/- 8.4 years) before and 4 months after successful coronary angioplasty (PTCA). Restenosis was defined as residual diameter stenosis > 50%. Although 96 patients (65%) had not developed restenosis at 4 months' invasive follow-up, subjective assessment of general well-being was unchanged in 26% or worse in 71%; overall anginal status and exercise performance had however improved. Of 71 men younger than 60 years who had no restenosis at follow-up, 4 men retired and 13 remained on medical leave. The striking disparity between subjective and objective parameters was not related to significant differences of age, exercise capacity, and left ventricular ejection fraction, as well as to baseline characteristics (previous myocardial infarction, extent of coronary heart disease, comorbidity) compared with 52 patients with restenosis. Thus, despite documented sustained success after PTCA, the majority of patients failed to resume the status of subjective well-being.