Re: "Applying recursive partitioning to a prospective study of factors associated with adherence to mammography screening guidelines".
Explore the source record for details and available documents.
Breast Neoplasms↗
Biomedical subjects
Martin Radespiel-Tröger
Publications and source records attributed to Martin Radespiel-Tröger.
Pancreatic endoprostheses in chronic pancreatitis: criteria to predict stent occlusion.
BACKGROUND: Good clinical results of main pancreatic duct (MPD) stent placement in chronic pancreatitis (CP) are clouded by early stent occlusion. The aim of this study was to increase knowledge about stent occlusion and its effects on clinical symptoms, and to define criteria that enable the prediction of clogging. METHODS: A total of 100 pancreatic endoprostheses of 47 patients (32 men, 15 women; mean age, 53 years; standard deviation, 9 years) with CP were bench tested by simulating the pathophysiologically increased MPD pressure. The main study parameter was the reduction of water flow through clogged stents in comparison with native endoprostheses of identical type, length, and diameter. Major stent occlusion was defined as flow reduction by > or = 75%. The association between time to stent occlusion and stent- or patient-related variables was evaluated. RESULTS: Occlusion took place in nearly all endoprostheses (97%). No significant association of occlusion with clinical or blood parameters was found. Multifactorial analysis proved 4 risk factors for major stent occlusion: (A) stent diameter > 8.5F, (B) stent length > 8 cm, (C) female gender, (D) exocrine pancreatic insufficiency that required regular oral enzyme supplementation. According to the relative risk, these factors were given the following scores: A, 3 points; B to D, 2 points. Stents in patients with a score sum > 5 showed a significantly higher risk of major stent occlusion within 90 days. CONCLUSIONS: Stent clogging in CP seems to be an inevitable phenomenon. Because clinical and laboratory data do not reliably indicate clogging, stent removal or exchange should be performed in high-risk patients (score sum > 5) within 3 months.
Adult↗
Restricted-expressed proliferation-associated protein (Repp86) expression in squamous cell carcinoma of the oral cavity.
PURPOSE: To determine the expression of repp86 (restricted-expressed protein of 86 kDa theoretical molecular mass), a proliferation- associated protein expressed in S-, G(2)- and M-phases of the cell cycle, in samples of normal mucosa as well as squamous cell carcinoma of the oral cavity (OSCC). PATIENTS AND METHODS: The repp86 labeling index (LI) was determined imunohistochemically in ten samples of normal oral mucosa and 59 samples of OSCC. Repp86 LI was correlated with tumor stage, histopathologic grading, and the expression of Ki-67 and topoisomerase IIalpha. RESULTS: Repp86 was detectable in all tissues analyzed. The mean LI was 4.7% for normal mucosa and 18.4% for squamous cell carcinoma (p < 0.0001). Repp86 expression was not related to tumor size, lymph node invasion, or histopathologic grading but was positively correlated with Ki-67 index (r = 0.48; p < 0.01) as well as with topoisomerase IIalpha (r = 0.39; p < 0.01). Ki-67 and topoisomerase IIalpha levels were also significantly correlated with each other (r = 0.34; p < 0.05). CONCLUSION: These results indicate that repp86 expression can be an additional proliferation marker among Ki-67 and topoisomerase IIalpha in OSCC. Further research will be directed at the evaluation of the prognostic value of repp86 expression in OSCC as well as in leukoplakia and early-stage OSCC.
Adult↗
Ten years experience with piezoelectric extracorporeal shockwave lithotripsy of gallbladder stones.
BACKGROUND: A critical review of the experience with extracorporeal shockwave lithotripsy (ESWL) of gallbladder stones is needed to clarify whether this method should continue to be applied to patients. METHODS: Patients with symptomatic gallbladder stones were treated by piezoelectric ESWL according to a prospective protocol between 1988 and 1997. ESWL treatment was limited to a maximum of three (solitary stones <20 mm diameter) to five sessions (larger solitary or multiple stones) and 3000 pulses per session. Univariate and multivariate analyses of pretreatment and treatment variables were performed to investigate their impact on fragmentation efficacy and stone clearance. A tree-based analysis was used to identify prognostically homogenous subgroups of individuals with maximum benefit from ESWL. RESULTS: Four hundred and eight patients, 76% female and 24% male, with a mean age of 46 (SD, 13) years, were selected for evaluation. Cox regression analysis identified three pretreatment variables with significant prognostic impact: (1) number of gallstones >1 (relative risk, 2.6 (95% CI, 1.9-3.5)), (2) size of stones >17 mm (1.7 (1.4-2.2)), and (3) computed tomography (CT) density of stones >55 Hounsfield units (H) (1.4 (1.1-1.8)). According to tree-based analysis, the stone clearance rate after 1 year was 85% (95% CI, 75-91%) for solitary stones <16 mm, 79% (70-86%) for solitary stones > or =16 mm with a CT density <84 H, 45% (32-55%) for solitary stones > or =16 mm with a CT density > or =84 H, and 42% (30-51%) for multiple stones. Five years after stone clearance, recurrence occurred in 43% of patients (95% CI, 39-47%). CONCLUSIONS: ESWL treatment showed an acceptable stone clearance in the case of small solitary gallbladder stones (<16 mm) or larger solitary stones with a CT density <84 H, but a very low success rate in the case of multiple stones. The poor long-term success, however, is an important argument against the use of ESWL of gallbladder stones.
Adolescent↗
Improved prediction of recurrence after curative resection of colon carcinoma using tree-based risk stratification.
BACKGROUND: Patients who are at high risk of recurrence after undergoing curative (R0) resection for colon carcinoma may benefit most from adjuvant treatment and from intensive follow-up for early detection and treatment of recurrence. However, in light of new clinical evidence, there is a need for continuous improvement in the calculation of the risk of recurrence. METHODS: Six hundred forty-one patients with R0-resected colon carcinoma who underwent surgery between January 1, 1984 and December 31, 1996 were recruited from the Erlangen Registry of Colorectal Carcinoma. The study end point was time until first locoregional or distant recurrence. The factors analyzed were: age, gender, site in colon, International Union Against Cancer (UICC) pathologic tumor classification (pT), UICC pathologic lymph node classification, histologic tumor type, malignancy grade, lymphatic invasion, venous invasion, number of examined lymph nodes, number of lymph node metastases, emergency presentation, intraoperative tumor cell spillage, surgeon, and time period. The resulting prognostic tree was evaluated by means of an independent sample using a measure of predictive accuracy based on the Brier score for censored data. Predictive accuracy was compared with several proposed stage groupings. RESULTS: The prognostic tree contained the following variables: pT, the number of lymph node metastases, venous invasion, and emergency presentation. Predictive accuracy based on the validation sample was 0.230 (95% confidence interval [95% CI], 0.227-0.233) for the prognostic tree and 0.212 (95% CI, 0.209-0.215) for the UICC TNM sixth edition stage grouping. CONCLUSIONS: The prognostic tree showed superior predictive accuracy when it was validated using an independent sample. It is interpreted easily and may be applied under clinical circumstances. Provided that their classification system can be validated successfully in other centers, the authors propose using the prognostic tree as a starting point for studies of adjuvant treatment and follow-up strategies.
Adenocarcinoma↗
Bagging survival trees.
Predicted survival probability functions of censored event free survival are improved by bagging survival trees. We suggest a new method to aggregate survival trees in order to obtain better predictions for breast cancer and lymphoma patients. A set of survival trees based on B bootstrap samples is computed. We define the aggregated Kaplan-Meier curve of a new observation by the Kaplan-Meier curve of all observations identified by the B leaves containing the new observation. The integrated Brier score is used for the evaluation of predictive models. We analyse data of a large trial on node positive breast cancer patients conducted by the German Breast Cancer Study Group and a smaller 'pilot' study on diffuse large B-cell lymphoma, where prognostic factors are derived from microarray expression values. In addition, simulation experiments underline the predictive power of our proposal.
Breast Neoplasms↗
Low-molecular-weight heparin does not prevent acute post-ERCP pancreatitis.
BACKGROUND: Studies suggest that heparin has anti-inflammatory effects that could prevent acute post-ERCP pancreatitis. The aim of this investigator-initiated, prospective, randomized, double-blind, multicenter study was to determine whether low-molecular-weight heparin can prevent acute post-ERCP pancreatitis. METHODS: Patients at increased risk for acute post-ERCP pancreatitis based on assessment of known risk factors were randomized to receive low-molecular-weight heparin (Certoparin 3000 IU subcutaneously) or placebo (saline solution 0.3 mL subcutaneously) the day before ERCP. The drug was given 2 hours before and 22 hours after ERCP. Documentation and follow-up included patient history, risk factors for acute post-ERCP pancreatitis, procedure-related data, assessment of pain (visual analogue scale, need for pain medication), laboratory findings before and after ERCP (0, 4, and 24 hours), as well as post-ERCP complications. The two-sided Fisher exact test was used for statistical comparison, and a p value < or =0.05 was considered significant. RESULTS: A total of 458 patients were enrolled in the study. Data from 10 patients could not be evaluated, leaving 221 patients in the low-molecular-weight heparin group and 227 in the placebo group (total 448 patients; 135 men, 313 women; mean age 58 [15] years). Low-molecular-weight heparin and placebo groups were comparable with regard to risk factors for acute post-ERCP pancreatitis (gender distribution, age <65 years, history of pancreatitis, pancreas divisum, disorders of sphincter of Oddi) and procedure-related data (difficult cannulation, diagnostic or therapeutic ERCP, needle-knife papillotomy, endoscopic sphincterotomy, biliary or pancreatic procedure, pancreatic contrast injection, success and final diagnosis of ERCP). Acute post-ERCP pancreatitis occurred in 8.5% (38/448), with one death resulting from severe pancreatitis. Low-molecular-weight heparin offered no benefit compared with placebo based on the frequency of acute post-ERCP pancreatitis (low-molecular-weight heparin, 18/221 vs. placebo, 20/227; p=0.87) and the severity of acute post-ERCP pancreatitis (low-molecular-weight heparin, 14 mild, 3 moderate, one severe; placebo, 18 mild, two moderate, 0 severe). The 24-hour serum amylase values and 24-hour pain scores did not differ significantly between the low-molecular-weight heparin group and the placebo group. Bleeding complications occurred in two patients, both in the low-molecular-weight heparin group (one mild, one moderate). CONCLUSIONS: Prophylactic subcutaneous administration of low-molecular-weight heparin does not prevent acute post-ERCP pancreatitis.
Acute Disease↗
Anti-TGFbeta1 antibody for modulation of expression of endogenous transforming growth factor beta 1 to prevent fibrosis after plastic surgery in rats.
The cytokine transforming growth factor beta 1 (TGFbeta1) substantially influences synthesis of extracellular matrix, fibrosis, and neoangiogenesis during wound healing in a dose dependent manner. We carried out experiments in rats to measure the degree of reduction of disorders of wound healing and fibrosis produced by inhibition of endogenous TGFbeta1 by polyclonal antibodies (poAB). A free myocutaneous gracilis flap was transplanted from the groin to the neck region in 30 Wistar rats (300-450 g body weight). In 15 animals intraoperatively and daily from days 3 to 7 postoperatively, 1 microg anti-TGFbeta1 poAB in 500 microl of phosphate buffered saline (PBS) were injected into the neck region. Fifteen animals served as controls. On postoperative days 3, 4, 5, 7, 14, and 28 the expression of endogenous TGFbeta1 in cytoplasm was analysed by immunohistochemistry (ABC-POX; AEC), in situ hybridisation of TGFbeta1-mRNA, and Sirus Red staining of collagen matrix; it was quantified using labelling indices. Neutralisation of the TGFbeta1 activity by specific poAB resulted in inhibition of the cytoplasmatic expression compared with untreated animals. In the transition area between grafted tissue and graft bed, a significant reduction of TGFbeta1 expression (mean (S.D.) 34.7 (6.5)) was found from day 5 in the group treated with anti-TGFbeta1 poAB compared with the control group (mean (S.D.) 48.1 (6.6)) (P <0.03). Up to day 14 the endogenous expression of TGFbeta1 (mean (S.D.) 30.0 (2.8)) was reduced after the application of TGFbeta1 poAB compared with the control group (mean (S.D.) 44.0 (12.3)). Sirus Red staining indicated a more complex packed structure and generally more prominent collagen types I-IV fibres in untreated animals than in animals that were given anti-TGFbeta1 poAB. Expression of TGFbeta-mRNA by in situ hybridisation was reduced in fibroblasts in animals that were given anti-TGFbeta1 poAB. The results indicate that anti-TGFbeta1 might improve the healing of free flaps in the graft beds of patients who are prone to excessive fibrosis.
Anastomosis, Surgical↗
Improved free vascular graft survival in an irradiated surgical site following topical application of rVEGF.
PURPOSE: Wound healing disorders following surgery in preirradiated tissue are clinically well known and may even become more crucial with the increasing use of neoadjuvant chemoradiation protocols. Both the expression of vascular endothelial growth factor (VEGF) and endoglin (CD105) play a key role in neovascularization and wound healing after soft tissue grafts in irradiated and nonirradiated tissue. Modulation of neovascularization through the application of recombinant VEGF (rVEGF) may be a therapeutic option to reduce wound healing disorders in irradiated tissue. An experimental in vivo model was used to study the possible role of rVEGF for reduction of wound healing disorders and the promotion of neovascularization. METHODS AND MATERIALS: A free myocutaneous gracilis flap was transplanted from the groin into the neck region of Wistar rats (weight 300-500 g) with and without previous irradiation of the neck region with 40 Gy: Group 1 (n = 7) radiotherapy alone; Group 2 (n = 14) flap transplantation alone and rVEGF; Group 3 (n = 14) radiotherapy, transplantation, and rVEGF. Time interval between irradiation and grafting was 10 +/- 1 day. 1.0 micro g rVEGF/500 microL phosphate-buffered saline was applied s.c. intraoperatively and on Days 1 through 7. Neovascularization (CD105) and endogenous VEGF expression were analyzed by means of immunohistochemistry on Days 3, 5, 7, 14, and 28 postoperatively and quantified as labeling indices (LI). RESULTS: After irradiation there was a continuous significant reduction of the cytoplasmic VEGF expression (MEAN LI: 0.018 +/- 0.048) compared with the nonirradiated control (mean LI: 0.042 +/- 0.006) (p < 0.001). VEGF expression after flap transplantation without irradiation after VEGF application was at a constantly higher level from Day 3 (mean LI: 0.044 +/- 0.01) to Day 28 postoperatively compared with the control group (Day 3, mean LI: 0.028 +/- 0.006) (p < 0.001). As an indication of increased neovascularization after the local application of rVEGF, a significantly increased expression of CD105 was found in the transition area and graft bed from Day 7 on (p < 0.001). After irradiation and grafting there was a significant overall increase in the VEGF- and CD105-expression throughout Day 28 after rVEGF in the transition area (p < 0.001). CONCLUSION: Whereas irradiation alone led to a downregulation of the endogenous VEGF expression, rVEGF application resulted in an increased expression and in a CD105 associated neovascularization after soft tissue grafting in irradiated tissues. Application of rVEGF may enable modulation of wound healing by influencing neovascularization. This could indicate a possible clinical approach for reducing fibrosis and chronic wound healing disorders in irradiated tissues.
Animals↗
Continuous positive airway pressure treatment rapidly improves insulin sensitivity in patients with obstructive sleep apnea syndrome.
The obstructive sleep apnea syndrome is typically associated with conditions known to increase insulin resistance as hypertension, obesity, and diabetes. We investigated whether obstructive sleep apnea itself is an independent risk factor for increased insulin resistance and whether continuous positive airway pressure (CPAP) treatment improves insulin sensitivity. Forty patients (apnea-hypopnea index > 20) were treated with CPAP. Before, 2 days after, and after 3 months of effective CPAP treatment, hyperinsulinemic euglycemic clamp studies were performed. Insulin sensitivity significantly increased after 2 days (5.75 +/- 4.20 baseline versus 6.79 +/- 4.91 micromol/kg.min; p = 0.003) and remained stable after 3 months of treatment. The improvement in insulin sensitivity after 2 days was much greater in patients with a body mass index less than 30 kg/m2 than in more obese patients. The improved insulin sensitivity after 2 nights of treatment may reflect a decreasing sympathetic activity, indicating that sleep apnea is an independent risk factor for increased insulin resistance. The effect of CPAP on insulin sensitivity is smaller in obese patients than in nonobese patients, suggesting that in obese individuals insulin sensitivity is mainly determined by obesity and, to a smaller extent, by sleep apnea.
Body Mass Index↗
In Vivo TGF-beta 3 expression during wound healing in irradiated tissue. An experimental study.
BACKGROUND: Wound-healing disorders frequently present a clinical problem in patients with squamous epithelial carcinomas of the head and neck region after surgical interventions such as grafts of free flaps in preirradiated graft bed tissues. Here, inflammatory changes and the expression of cytokines can lead to delayed healing and to the induction of fibrosis. The isoforms of the transforming growth factor beta (TGF-beta(1-3)) play a central role in this process. While it was possible to experimentally show a fibrosis-inducing activity for TGF-beta(1) and TGF-beta(2), a fibrosis-reducing and radioprotective effect has been described for TGF-beta(3) on epithelial cells and fibroblasts. The influence of irradiation and tissue grafting on the TGF-beta(3) expression, however, remains uncertain. The objective of the in vivo study was therefore to analyze the expression profile of TGF-beta(3) in the graft bed and in the transition area between the graft and the graft bed after irradiation and/or after surgery. MATERIAL AND METHODS: A total of 48 Wistar rats (male, weight 300-500 g) were used in the study. A free myocutaneous gracilis flap was transplanted in 30 rats: group 1 (n = 18 rats) no transplantation, only irradiation (3 x 10 Gy); group 2 (n = 14 rats) transplantation without preoperative irradiation; group 3 (n = 16 rats) transplantation following preoperative irradiation (3 x 10 Gy). The interval between radiotherapy and grafting was 4 weeks. Tissue samples were taken perioperatively and postoperatively after 3, 4, 7, 11, 14, 28, and 30 days from the transition area between the graft and the graft bed and from the graft bed itself. The TGF-beta(3) expression was analyzed immunohistochemically (labeling index) both qualitatively and quantitatively and checked for statistical differences between the groups (p < 0.05). RESULTS: The success rate for graft healing was 75% in the group irradiated with 30 Gy, and 86% in the nonirradiated group. The rats that were irradiated but not operated on showed significantly (p = 0.04) reduced TGF-beta(3) expression in the graft bed immediately after the end of the irradiation. Whereas only minor differences in TGF-beta(3) expression were observed postoperatively in the graft bed and in the transition area between the graft and the graft bed in the group where a graft was carried out without preirradiation, the group that was preirradiated with subsequent grafting showed a significantly reduced expression in the bed (p = 0.018). CONCLUSION: After irradiation, it was possible to measure reduced TGF-beta(3) expression in the irradiated graft bed. The exogenous application of TGF-beta(3) could therefore present a new therapeutic approach for improving wound healing through radioprotection of nontransformed epithelial cells and fibroblasts after preoperative radiotherapy and surgery.
Animals↗
Agreement of two different methods for measurement of heart rate variability.
BACKGROUND: The widespread use of affordable devices with sufficient precision for measurement of heart rate variability (HRV) might lead to early detection of abnormalities in a large number of high-risk patients and athletes. The purpose of this study was to determine the limits of agreement of two devices for measuring HRV parameters differing in price and assumed precision. SUBJECTS AND METHODS: 36 healthy subjects (22 men and 14 women) with a mean age of 27.4 (SD 11.1) years were included. The two devices used for comparison were PowerLab with Chart software as the reference golden standard, and Polar Transmitter/Advantage with Precision Performance software, respectively. Measurements included the following heart rate variability parameters: heart rate, range of R-R-interval duration, SDNN, rMSSD, total Power, VLF power, LF power, and HF power. Measurements were taken during metronomic respiration over a total period of 3 minutes. Statistical analysis was performed according to Bland and Altman and by means of scatterplots and Spearman correlation coefficients. RESULTS: Good agreement was found for heart rate (95 % CI of limits of agreement: -0.7-0.6 bpm; r = 0.999), range of duration of R-R-intervals (95 % CI: -18.9-17.0 ms; r = 0.997), rMSSD (95 % CI: -1.5-2.5 ms; r = 0.999), and SDNN (95 % CI: -3.0-3.1 ms; r = 0.997). Correlation of measurements was high for the variables total Power, VLF power, LF power, and HF power. Analysis of method agreement for frequency domain variables was statistically not feasible. CONCLUSION: The level of agreement for the analyzed time domain variables between the reference golden standard and the inexpensive device is sufficient to permit initial screening by family doctors, and self-administration by high-risk patients and athletes.
Adult↗
Implant stability and histomorphometry: a correlation study in human cadavers using stepped cylinder implants.
The aim of the present study was to determine the correlation between the primary stability of dental implants placed in edentulous maxillae and mandibles, the bone mineral density and different histomorphometric parameters. After assessing the bone mineral density of the implant sites by computed tomography, 48 stepped cylinder screw implants were installed in four unfixed human maxillae and mandibles of recently deceased people who had bequeathed their bodies to the Anatomic Institute I of the University of Erlangen-Nuremberg for medical-scientific research. Peak insertion torque, Periotest values and resonance frequency analysis were assessed. Subsequently, histologic specimens were prepared, and bone-to-implant contact, the trabecular bone pattern factor (TBPf), the density of trabecular bone (BV/TV) and the height of the cortical passage of the implants were determined. The correlation between the different parameters was calculated statistically. The mean resonance frequency analysis values (maxilla 6130.4+/-363.2 Hz, mandible 6424.5+/-236.2 Hz) did not correlate with the Periotest measurements (maxilla 13.1+/-7.2, mandible -7.9+/-2.1) and peak insertion torque values (maxilla 23.8+/-2.2 N cm, mandible 45.0+/-7.9 N cm) (P=0.280 and 0.193, respectively). Again, no correlations could be found between the resonance frequency analysis, the bone mineral density (maxilla 259.2+/-124.8 mg/cm(3), mandible 349.8+/-113.3 mg/cm3), BV/TV (maxilla 19.7+/-8.8%, mandible 34.3+/-6.0%) and the TBPf (maxilla 2.39+/-1.46 mm-1, mandible -0.84+/-3.27 mm-1) (P=0.140 and 0.602, respectively). However, the resonance frequency analysis values did correlate with bone-to-implant contact of the oral aspect of the specimens (maxilla 12.6+/-6.0%, mandible 35.1+/-5.1%) and with the height of the crestal cortical bone penetrated by the implants in the oral aspect of the implant sites (maxilla 2.1+/-0.7 mm, mandible 5.1+/-3.7 mm) (P=0.024 and 0.002, respectively). The Periotest values showed a correlation with the height of the crestal cortical bone penetrated by the implants in the buccal aspect of the implant sites (maxilla 2.5+/-1.2 mm, mandible 5.4+/-1.2 mm) (P=0.015). The resonance frequency analysis revealed more correlations to the histomorphometric parameters than the Periotest measurements. However, it seems that the noninvasive determination of implant stability has to be improved in order to give a more comprehensive prediction of the bone characteristics of the implant site.
Aged↗
Bone contact, growth, and density around immediately loaded implants in the mandible of mini pigs.
The aim of the study was to compare the bone mineral apposition rate (BMAR) of immediately loaded implants with an unloaded control during the early healing phase in the partially edentulous mandible. In seven mini pigs, three premolars and the first molar were removed in the left mandible. Three months later, five implants were installed. Four implants received a fixed provisional restoration and were loaded immediately. The most anterior implant was used as unloaded control. Polychromatic fluorescence labelling was performed to assess the BMAR. After 4 months, the implants were retrieved together with the adjacent bone. Histological specimens were prepared and subjected to a fluorescence microscopic and histomorphometric analysis. Two provisional restorations were found partially lost at the end of the observation period. One implant that had lost the splinting fixation showed soft connective tissue healing. The BMAR did not differ statistically significantly between loaded and unloaded implants and within the single groups during the observation period (BMARloaded days 14-42=1.8+/-0.2 microm/d, BMARloaded days 42-70=1.8+/-0.1 microm/d, BMARloaded days 70-98=1.6+/-0.1 microm/d, pBMARloaded days 14-42/42-70/70-98 =0.156, BMARunloaded days 14-42=1.7+/-0.1 microm/d, BMARunloaded days 42-70=1.8+/-0.2 microm/d, BMARunloaded days 70-98=1.6+/-0.4 microm/d, pBMARunloaded days 14-42/42-70/70-98=0.368, pBMARloaded/unloaded days 14-42=0.073, pBMARloaded/unloaded days 42-70=0.098, pBMARloaded/unloaded days 70-98=0.262). Four months after implant placement, the bone-to-implant contact was 77.8+/-17.3% for the loaded and 78.0+/-5.8% for the unloaded implants (P=0.753). Immediate loading does not affect the bone mineral apposition rate when compared with unloaded implants. Rigid splinting seems to be the crucial factor for implant success. Uncontrolled masticatory forces can cause failure after partial loss of the provisional restoration.
Animals↗
Anatomic site evaluation of the zygomatic bone for dental implant placement.
Thirty human zygomatic bone specimens (15 females mean age 81.60 +/- 11.38 years, 15 males, mean age 78.47 +/- 6.58 years) were examined by quantitative computed tomography and histomorphometry. The aim of the study was to assess the bone mineral density, the trabecular bone volume and the trabecular bone pattern factor. Moreover, the anterior-posterior and the medio-lateral dimensions and the estimated implant length within the zygomatic bone were determined. For quantitative computed tomography the specimens were scanned together with a bone mimicking anthropomorphic reference phantom. The bone mineral density was calculated for the specimens in the plane of the intended direction of the implant placement. Subsequently, with the sawing and grinding technique, the specimens were prepared in the same plane for histomorphometry. The trabecular bone mineral density was 369.95 +/- 188.80 mg/cm3 for the female and 398.94 +/- 99.11 mg/cm3 for the male specimens (P = 0.23). The male trabecular bone volume showed a value of 27.32 +/- 9.49%, while the female group reached a value of 19.99 +/- 7.60% (P = 0.23). The trabecular bone pattern factor was 1.2 x 10-2 +/- 1.28 mm-1 for the male and 1.02 +/- 0.96 mm-1 for the female specimens (P = 0.045). The study reveals that the zygomatic bone consists of trabecular bone with parameters that are unfavourable for implant placement. However, the success of implants placed in the zygomatic bone is secured by the employment of at least four cortical portions.
Aged↗
Transforming growth factor beta1 and beta2 (TGFbeta2 / TGFbeta2) profile changes in previously irradiated free flap beds.
BACKGROUND: Following preoperative radiotherapy prior to ablative surgery of squamous epithelial carcinomas of the head and neck region, inflammatory changes and the expression of cytokines involved in wound healing could be observed. These processes lead to a delayed healing of free flaps in the graft bed. The aim of the present experimental study was to analyze the expression profiles of transforming growth factor (activated TGFbeta(1), TGFbeta(2)) and latency-associated peptide (LAP) in the irradiated graft beds and the transition area between grafts and irradiated graft beds. METHODS: In Wistar rats (male, weight 300-500 g) undergoing preoperative irradiation of the neck region with 30 Gy (30 animals) and non-irradiated rats (42 animals), a free myocutaneous gracilis flap taken from the groin was transplanted to the irradiated region of the neck. The interval between irradiation and transplantation was 4 weeks. In each group on postoperative days 3, 7, 14, and 28, cytoplasmatic expression of activated TGFbeta(1), LAP, and TGFbeta(2) was analyzed by immunohistochemistry to determine labeling indices (positive stained cells/total cells). RESULTS: The success rate in graft beds irradiated with 30 Gy was 76% and in non-irradiated graft beds was 86% (p =.02). In the graft beds irradiated with 30 Gy, there was an increased expression of activated TGFbeta(1) (range, 19.0-33.0), LAP (14.0-21.0), and TGFbeta(2) (3.0-19.5) together with obvious fibrosis. The expression was located in perivascular fibroblasts and endothelial cells. In contrast, a lower expression of activated TGFbeta(1) (11.0-21.0), LAP (1.0-8.0), and TGFbeta(2) (0.0-0.9) (p =.006) was observed in non-irradiated graft beds. In the transition area between graft and irradiated graft bed, high expression of activated TGFbeta(1) (37.0), LAP (19.0), and TGFbeta(2) (16.7-33.4) was observed on the 3rd postoperative day in contrast to the transition area in non-irradiated graft beds (activated TGFbeta(1) 26.0, LAP 7.0, and TGFbeta(2) 0.l). CONCLUSION: The radiation induced, increased de novo synthesis of LAP, activation of TGFbeta(1), and increased expression of TGFbeta(2) may represent at least one mechanism for the increased fibrosis and wound healing disorders seen in irradiated tissues and in the transition area to graft tissue. The expression of TGFbeta(1,) LAP, and TGFbeta(2) might possess prognostic value with regard to wound healing and fibrosis in previously irradiated graft beds.
Animals↗
Vascularization in the transition area between free grafted soft tissues and pre-irradiated graft bed tissues following preoperative radiotherapy in the head and neck region.
BACKGROUND: The healing of free vascular grafts in a pre-irradiated graft bed is characterized by an increased risk of wound healing disorders. For that reason, the aim of this study was to examine quantitative vascularization pattern between free vascular grafts and the pre-irradiated graft bed as a function of the preoperative irradiation dose. METHODS: A total of 217 free microvascular hard and soft tissue grafts were used within 199 patients in the head and neck region to cover defects after ablative tumor surgery. Seventy-six patients (group 1) had no prior radiation (RT), 50 patients (group 2) were treated with preoperative radiochemotherapy using 40 to 50 Gy and 5-FU/cisplatin, and 73 patients (group 3) had prior RT (60-70 Gy) between 1 and 7 years before surgery. After healing of the grafts, samples were taken from 42 patients from the graft, the irradiated graft bed, and the transition area between graft and irradiated graft bed. Samples were analyzed as follows: capillary sprouting, structural changes, and distribution patterns were analyzed by immunohistochemical staining (CD34 labeling of capillary endothelium). Three histological sections (2-4 microm) per sample were examined histomorphometrically (ratio capillary area/total area, capillary lumen, and the number of capillaries) by (National Institute of Health) NIH-image-digitized measurements. A statistical analysis was performed using the Kruskal-Wallis and Mann-Whitney test (two-tailed p <.05). RESULTS: The success rate of vascular grafts in group 1 (0 Gy) was 94%, in group 2 (40-50 Gy/5-FU/cisplatin) 90%, in group 3 (60-70 Gy) 84%. In contrast to groups 1 and 2, group 3 showed qualitatively reduced and more irregular capillary distribution with more marked pericapillary fibrosis in the irradiated tissue. Quantitatively, the ratio capillary area/total area, as a marker of improved capillarization, was significantly reduced in group 3 (median 0.01; IQR 0.02) compared with group 1 (median 0.53; IQR 0.32) and group 2 (median 0.44; IQR 1.40) (p <.001). CONCLUSION: After preoperative RT, vascularization of the graft bed decreased continuously as a function of the total dose and time after RT. The results strongly advocate the use of a primary reconstruction after a time interval between 4 and 6 weeks following preoperative RT and suggest the use of a total radiation dose of 40 to 50 Gy.
Adult↗
Morbidity of harvesting of retromolar bone grafts: a prospective study.
20 retromolar bone grafts were harvested in outpatients for augmentation of the implant site from January to June 2000 (10 female, 10 male, 40.9 +/- 12.8 years, minimum 17 years, maximum 66 years). The aim of the study was to assess typical complications of this procedure in a prospective manner. For the determination of the superficial sensory function of the inferior alveolar and the lingual nerve, an objective method was used. The bone grafts were harvested for single tooth reconstruction. In 14 cases a ridge augmentation and in 6 cases an endoscopically controlled crestal sinus floor elevation was performed. Preoperatively, the height of bone above the cranial aspect of the inferior alveolar nerve in the retromolar region was assessed radiologically with known markers. The maximum mouth opening was determined. The superficial sensory function of the inferior alveolar and the lingual nerve was assessed with the Pointed-Blunt Test, the Two-Point-Discrimination Test and the objective method of the 'Pain and Thermal Sensitivity' Test (PATH Test). Moreover, the pulp sensitivity of the teeth of the donor site was determined by cold vitality testing. All tests were repeated 1 week postoperatively. Intraoperatively, the width of the retromolar region was measured with a caliper. The patients rated the operative strain on a visual analogue scale. The height of bone above the inferior alveolar nerve in the retromolar region was 11.0 +/- 2.2 mm. The width of the retromolar area was 14.2 +/- 1.9 mm. Postoperatively, the maximal mouth opening changed significantly (40.8 +/- 3.5 mm preoperatively, 38.9 +/- 3.7 mm postoperatively, P = 0.006). However, the reduction was not relevant clinically. A direct injury of the inferior alveolar or lingual nerve did not occur. A sensitivity impairment could not be detected for either of the nerves by the different test methods 1 week postoperatively. The operative strain related to the donor site was significantly less than the strain generated by the implant placement (rating on a visual analogue scale 2.8 +/- 1.0 and 4.1 +/- 2.0, respectively, P = 0.027). Retromolar bone grafts are a viable method for augmentation of the implant site in conjunction with single tooth reconstruction with low strain on the patient and minimal risk of complications.
Adolescent↗