Open reduction and internal fixation of paediatric maxillozygomatic complex fractures: An 11-year multicentric retrospective study.

BACKGROUND/AIM: Paediatric maxillozygomatic complex (MZC) fractures are uncommon, and there is a scarcity of data regarding their surgical treatment. The aim of this study was to analyse choices and outcomes of open reduction and internal fixation (ORIF) for MZC fractures among 14 maxillofacial centers around the world. MATERIALS AND METHODS: This multicentric retrospective observational study included patients ≤16 years of age with quadripod MZC fractures treated with ORIF from January 2011 and December 2022. The following data were collected: age, gender, dentition stage (deciduous, mixed, and permanent), cause of injury, type of fracture, surgical approach, site of osteosynthesis (infraorbital rim, zygomaticomaxillary buttress, frontozygomatic, and zygomaticotemporal sutures), material (titanium or resorbable) and number of plates used, and outcome. The minimum follow-up was 6 months. Statistical analyses were performed with Fisher's exact test or chi-squared test, as appropriate. RESULTS: Sixty-four patients (mean age, 12.3 years) with quadripod MZC fractures were included. Seventy-two percent of patients received a single-point fixation. The zygomaticomaxillary buttress was the most common site for fixation, both in single-point and two-point fixation schemes, especially in combination with the frontozygomatic suture. Increasing age was associated with a higher rate of plate removal (p < .001). Postoperative complications included 5 (7.8%) cases of wound infections, 2 (3.1%) infraorbital paraesthesia, 1 (1.6%) ectropion. Residual facial asymmetry was found in 5 (7.8%) patients and was not associated with the type of fixation (p > .05). CONCLUSIONS: This study highlights the possibility of using ORIF, even with a single point of fixation, for the treatment of displaced quadripod MZC fractures in the paediatric population. The zygomaticomaxillary buttress was the preferred site of fixation and allowed for adequate stabilization with no external scars and a low risk of tooth damage. Future prospective studies with long-term follow-up are needed to establish definitive surgical protocols and clarify the surgical decision-making.

Epidemiology, etiopathogenesis, and management of MRONJ: A European multicenter study.

INTRODUCTION: The purpose of this European multicenter study was to describe the general characteristics and risk factors of MRONJ lesions as well as their clinical diagnosis and management at different European Oral and Maxillofacial Surgery centers, in order to minimize selections biases and provide information about the epidemiology, etiopathogenesis, and the current trends in the treatment of MRONJ across Europe. MATERIALS AND METHODS: The following data were registered for each patient: gender; age at MRONJ diagnosis; past medical history; indication for antiresorptive or antiangiogenic therapy; type of antiresorptive medication; local risk factor for MRONJ; MRONJ Stage; anatomic location and symptoms; treatment; surgical complications; recurrence. RESULTS: A total of 537 patients (375 females, 162 males) with MRONJ were included. Statistically significant associations were found between patients with metastatic bone disease and recurrences (P < 0.0005) and between advanced MRONJ stages (stages 2 and 3) and recurrences (P < 0.005). Statistically significant associations were also found between male gender and recurrences (P < 0.05), and between MRONJ maxillary sites and recurrences (P < 0.0000005). CONCLUSIONS: A longer mean duration of antiresorptive medications before MRONJ onset was observed in patients affected by osteoporosis, whereas a shorter mean duration was observed in all metastatic bone cancer patients, and in particular in those affected by prostate cancer with bone metastases or multiple myeloma. Surgery plays an important role for the management of MRONJ lesions.

Patient's perception of recovery following surgical removal of mandibular third molars. A prospective european multi-center study.

This study evaluated patient's perception of recovery following surgical removal of mandibular third molars (SRM3s) including analyze of potential risk factors associated with impaired convalescent. Patient related parameters combined with preoperative questionnaires including Modified Dental Anxiety Scale, Oral Health Impact Profile-14, and Decayed, Missing, Filled Teeth index were correlated with questionnaires assessing pain, swelling, trismus, sick leave, social and working isolation, physical appearance, eating and speaking ability, diet variations, sleep impairment, impaired sensation of the lip, chin, and tongue, one month following SRM3s. Totally, 412 patients (223 females, 189 males) with mean age of 29.4 years were included. Treatment satisfaction and willingness to undergo similar surgery were reported by 92% and 95%, although 21% reported that the surgery and postoperative period had been worse than expected. Mean days with pain, sick leave, and swelling were 3.6, 2.1, and 3.6, respectively. Preoperative symptoms, dental anxiety level, and prolonged surgical time were associated with increased pain and swelling (P < 0.05). Pell and Gregory classification (I-IIIC) were associated with impaired sensation of the lower lip and chin (P < 0.05). Consequently, results from this study improve the surgeon's ability to predict parameters that predisposed to impaired recovery and neurosensory disturbances following SRM3s.

The epidemiology and management of odontomas: a European multicenter study.

INTRODUCTION: Odontoma is the most commonly diagnosed odontogenic tumor of the oral cavity. The objective of the present study was to assess the demographic variables, patterns, diagnostic features, and management issues of odontomas treated at several European departments of maxillofacial and oral surgery. MATERIALS AND METHODS: This study was conducted at 8 European departments of oral surgery between January 1, 2004, and December 31, 2018. Only patients with odontomas were included. The following data were recorded for each patient: gender, age, comorbidities, site, size of odontomas, radiographic features, type of odontoma, treatment of odontomas, treatment of associated teeth, complications, and recurrence. RESULTS: A total of 127 patients (70 male and 57 female patients) with odontomas were included. The mean age was 22 years; 71 odontomas were found in the mandible, whereas 56 in the maxilla. In the mandible, the most frequently involved subsite was the parasymphysis, while in the maxilla, the most common subsite was the upper incisor region. The mean size of included odontomas was 15.3 mm. On the whole, 62 complex odontomas, 50 compound odontomas, and 15 mixed-type odontomas were observed. Complete excision of the odontomas was performed in 121 patients. In 24 patients, the extraction of deciduous teeth was performed, and in 43 patients, one or more permanent teeth were removed. Finally, in 9 patients, a partial excision of the odontoma was performed. Recurrence was observed in 4 cases out of 127 patients. CONCLUSIONS: Dental practitioners should be aware of the distinct clinical and radiographic features of odontoma in order to perform an appropriate and early diagnosis. Conventional radiography, such as panoramic radiograph, is often sufficient technique for a diagnosis after clinical suspicion or for an incidental diagnosis to prevent later complications, such as impaction or failure of eruption of teeth.

The epidemiology and management of odontogenic keratocysts (OKCs): A European multicenter study.

The objective of the present study was to assess the epidemiology including demographic variables, diagnostic features, and the management of odontogenic keratocyst (OKCs) at several European departments of maxillofacial and oral surgery. This study is based on a systematic computer-assisted database that allowed the recording of data from treated OKCs. The following data were recorded for each patient: gender, age, voluptuary habits, comorbidities, site, size, radiographic features, treatment of OKCs, length of hospital stay, complications, recurrence, management and complications of eventual recurrence. A total of 405 patients, 249 male and 156 female, with 415 OKCs (407 sporadic and 8 syndromic lesions) were included in the study: 320 lesions were found in the mandible, whereas 95 were found in the maxilla. In the mandible, the most frequently involved subsite was the angle, whereas in the maxilla it was the molar region. The most frequently performed treatment option was enucleation plus curettage/peripheral ostectomy in 204 OKCs (recurrence rate, 9%). Decompression without residual cystectomy (recurrence rate, 66%), marsupialization with residual enucleation with the use of Carnoy's solution (recurrence rate, 50%), decompression with residual cystectomy (recurrence rate, 43%), and simple enucleation (recurrence rate, 24%) were the treatment options with the highest recurrence rates. An appropriate management of odontogenic keratocysts should be individualized, taking into consideration clinical and radiological findings, as well as patients' age and comorbidities.

Imaging of odontogenic keratocysts: a pictorial review.

INTRODUCTION: The aim of the present article was to review and depict the main radiological features of odontogenic keratocysts (OKCs), thus helping the differential diagnoses from other odontogenic cysts and neoplasms. EVIDENCE ACQUISITION: A review of articles published between January 2000 and October 2020 using Medline and the MeSH Term "odontogenic keratocyst" in combination with the following terms "imaging," "radiology," "panoramic radiograph," and "computed tomography," was performed. EVIDENCE SYNTHESIS: Radiographically, OKCs are well-defined unilocular or multilocular radiolucencies bounded by corticated margins. Most lesions are unilocular; instead, multilocular OKCs represent about the 30% of cases, mainly involving the posterior mandible. When, particularly in large lesions, OKCs display a multilocular presentation with adjacent satellite cysts (daughter cysts) a "soap-bubble appearance" can be recognized. DISCUSSION: Panoramic radiograph and CT still play an important role in the diagnosis and treatment planning of OKCs. Unfortunately, it may not be easy to differentiate OKCs from other odontogenic lesions, especially when they are small and unilocular. CONCLUSIONS: Histopathological findings are still necessary to obtain a definitive diagnosis.

Quality of life following maxillofacial trauma in the elderly: a multicenter, prospective study.

BACKGROUND/AIMS: When facial trauma involves elderly patients, the possible presence of frailty and comorbidities in victims of trauma may worsen the posttraumatic symptoms and decrease quality of life. The aim of this multicenter study was to assess the quality of life following surgical or non-operative management of maxillofacial trauma in elderly patients. MATERIALS AND METHODS: This cohort study was based on the administration of validated self-administered questionnaires to all the geriatric patients (70 years or more) with facial fractures from the involved maxillofacial surgical units across Europe, since 1st January 2019 to 31st June 2019. The following questionnaires were administered: SF36 questionnaire; the VFQ-25 questionnaire; the Oral Health Impact Profile - 14 (OHIP14). Outcome variables were VFQ-25 and OHIP-14 results. RESULTS: A total of 37 patients (14 male and 23 female patients) met the inclusion criteria and were included in the study. Elderly patients had an improvement in almost all the categories examined by the SF-36 questionnaire 6 months after trauma, with the only exception of a worsening as for role limitations due to physical health. An improvement was observed in almost all the categories at SF-36 test. A worsening of scores of OHIP-14 for all the considered dimensions in the whole study population was observed too. CONCLUSIONS: Elderly patients following facial trauma experience significant emotional, social, and functional disturbances. We observed that emotional problems, energy/fatigue, social functioning, and generally social limitations played a great role in the decrease of QoL in elderly patients following maxillofacial trauma.

The epidemiology and management of ameloblastomas: A European multicenter study.

The present study aimed at assessing the epidemiology including demographic variables, diagnostic features, and management of ameloblastomas at several European departments of maxillofacial and oral surgery. The following data were recorded for each patient: gender, age, voluptuary habits, comorbidities, site, size, radiographic features, type, histopathological features, kind of treatment, length of hospital stay, complications, recurrence, management and complications of the recurrence. A total of 244 patients, 134 males and 110 females with ameloblastomas were included in the study. Mean age was 47.4 years. In all, 81% of lesions were found in the mandible, whereas 19% were found in the maxilla. Mean size of included ameloblastomas was 38.9 mm. The most frequently performed treatment option was enucleation plus curettage/peripheral ostectomy in 94 ameloblastomas, followed by segmental resection (60 patients), simple enucleation (46 patients), and marginal resection (40 patients). A recurrence (with a mean follow up of 5 years) was observed in 47 cases out of 244 ameloblastomas (19.3%). Segmental resection was associated with a low risk of recurrence (p = 0003), whereas enucleation plus curettage/peripheral ostectomy was associated with a high risk of recurrence (p = 0002). A multilocular radiographic appearance was associated with a high risk of recurrence (p < .05), as well as the benign solid/multicystic histologic type (p < .05). Within the limitations of the study it seems that the management of ameloblastomas will probably remain controversial even in the future. Balancing low surgical morbidity with a low recurrence rate is a difficult aim to reach.

Management of maxillofacial trauma in the elderly: A European multicenter study.

BACKGROUND/AIMS: Management of maxillofacial trauma in the geriatric population poses a great challenge due to anatomical variations and medical comorbidities. The aim of this study was to analyze the management variables, timing, and outcomes of facial fractures in elderly patients (aged 70 years or more) at several European departments of oral and maxillofacial surgery. MATERIALS AND METHODS: This study was based on a systematic computer-assisted database that allowed the recording of data from all geriatric patients with facial fractures from the involved maxillofacial surgical units across Europe between 2013 and 2017. RESULTS: A total of 1334 patients were included in the study: 665 patients underwent closed or open surgical treatment. A significant association (P < .005) was found between the presence of concomitant injuries and a prolonged time between hospital admission and treatment. The absence of indications to treatment was associated with comorbidities and an older age (P < .000005). CONCLUSIONS: Elderly patients require specific attention and multidisciplinary collaboration in the diagnosis and sequencing of trauma treatment. A prudent attitude may be kept in selected cases, especially when severe comorbidities are associated and function is not impaired.

Surgical management of unilateral body fractures of the edentulous atrophic mandible.

INTRODUCTION: Management of body fractures in patients with edentulous atrophic mandibles represents a challenging task due to patient's age, medical comorbidities, poor bone quality, and vascularity, as well as reduced contact area between the fracture ends. The aim of the study was to assess the demographic and clinical variables, the surgical technique, and outcomes of unilateral body fractures of the edentulous atrophic mandible managed at several European departments of oral and maxillofacial surgery. METHODS: This study is based on a systematic computer-assisted database that allowed the recording of data of all patients with fractures of the atrophic edentulous mandible from the involved maxillofacial surgical units across Europe between 2008 and 2017. The following data were recorded for each patient: gender, age, comorbidities, etiology, synchronous body injuries, degree of atrophy of the mandible according to Luhr classification, type of surgical approach and fixation, length of hospitalization, and presence and type of complications. RESULTS: A total of 43 patients were included in the study: 17 patients' mandibles were classified as class I according to Luhr, 15 as class II, and 11 as class III. All patients underwent open reduction and internal fixation by extraoral approach in 25 patients, intraoral in 15 patients, and mixed in 3 patients. A single 2.0 miniplate was used in 16 patients, followed by a single 2.4 reconstruction plate in 13 patients, by two 2.0 miniplates, and three 2.0 miniplates. Outcome was considered to be satisfying in 30 patients, with no complications. Complications were observed in 13 cases. CONCLUSIONS: Treatment of unilateral body fractures of the edentulous mandible must still be based on the type of fracture, degree of atrophy, experience of the surgeon, and patients' preference. An adequate stability can be obtained by different plating techniques that have to be appropriately tailored to every single specific patient.

The epidemiology of edentulous atrophic mandibular fractures in Europe.

INTRODUCTION: The objective of the present study was to assess the demographic variables, causes, and patterns of edentulous atrophic fractures of the mandible managed at several European departments of oral and maxillofacial surgery. The results of this multicenter collaboration over a 10-year period are presented. METHODS: The data of all patients with fractures of the atrophic edentulous mandible from the involved maxillofacial surgical units across Europe between January 1, 2008, and December 31, 2017 were recorded: gender; age; voluptuary habits; comorbidities; etiology; fracture sites; synchronous body injuries; atrophy of the mandible according to Luhr classification; eventual type of treatment; timing of the eventual surgery; length of hospital stay. RESULTS: A total of 197 patients (86 male and 111 female patients) with 285 mandibular fractures were included in the study. Mean age of the study population was 75 years. Statistically significant associations were found between Luhr classes I - II and condylar fractures on one hand (p < .0005), and between Luhr class III and body and parasymphyseal fractures on the other hand (p < .05). Finally, 135 patients underwent open reduction and internal fixation, 56 patients did not undergo any intervention, and 6 patients underwent closed reduction. No statistically significant association was observed between treatment, timing of treatment, comorbidities, and concomitant injuries. CONCLUSIONS: The management of edentulous atrophic mandibular fractures remains challenging. Treatment decisions should continue to be based on the clinician's previous experience and on the degree of bone resorption in edentulous mandible in relation to fracture subsites.

Motor vehicle accidents-related maxillofacial injuries: a multicentre and prospective study.

OBJECTIVES: The purpose of this European multicenter prospective study was to obtain more precise information about the demographic characteristics and etiologic/epidemiologic patterns of motor vehicle accidents (MVA)-related maxillofacial fractures. STUDY DESIGN: Of the 3260 patients with maxillofacial fractures admitted within the study period, 326 traumas were caused by MVAs with a male/female ratio of 2.2:1. RESULTS: The maximum incidence was found in Zagreb (Croatia) (18%) and the minimum in Bergen (Norway) (0%). The most frequent mechanisms were car accidents, with 177 cases, followed by motorcycle accidents. The most frequently observed fracture involved the mandible, with 199 fractures, followed by maxillo-zygomatic-orbital (MZO) fractures. CONCLUSIONS: In all the 3 groups (car, motorcycle, and pedestrian), mandibular and MZO fractures were the 2 most frequently observed fractures, with some variations. The importance of analyzing MVA-related facial injuries and their features and characteristics should be stressed.

The "European Mandibular Angle" research project: the analysis of complications after unilateral angle fractures.

OBJECTIVE: The aim of this study was to analyze the complications and outcomes of surgical treatment of angle fractures managed at departments of maxillofacial surgery in several European countries. STUDY DESIGN: Patients hospitalized with unilateral isolated angle fractures between 2013 and 2017 were included. The following data were recorded: gender and age of patients, fracture etiology, presence of the third molar, maxillomandibular fixation, osteosynthesis technique, and complications. RESULTS: In total, 489 patients were included in the study. The Champy technique was found to be the most frequently chosen osteosynthesis technique. Sixty complications were observed, at a rate of 12.3%. Complications were associated with the absence of third molars (P < .05). Instead, the Champy technique was associated with fewer complications (P < .05), in comparison with the other adopted techniques. CONCLUSIONS: The management of angle fractures still represents a challenging task with a significant complication rate. The Champy technique still seems to be a valid option for the treatment of such injuries.

The "European zygomatic fracture" research project: The epidemiological results from a multicenter European collaboration.

PURPOSE: Fractures of the zygomaticomaxillary complex (ZMC) are common injuries that may lead to loss of an aesthetically pleasing appearance and functional impairment. The aim of this study was to analyze the demographics, causes, characteristics, and outcomes of zygomatic fractures managed at several European departments of oral and maxillofacial surgery. MATERIALS AND METHODS: This study is based on a multicenter systematic database that allowed the recording of all patients with ZMC fractures between 1 January 2013 and 31 December 2017. The following data were recorded: gender, age, personal medical history, etiology, side of zygomatic fracture, classification of ZMC fracture, associated maxillofacial fractures, symptoms at diagnosis, type of performed treatment, and sequelae/complications. RESULTS: A total of 1406 patients (1172 males, 234 females) were included in the study. Statistically significant correlations were found between assault-related ZMC fractures and the A3 class (p < .0000005) and between Infraorbital Nerve (ION) anesthesia and B class (p < .00000005). CONCLUSION: The most frequent cause of ZMC fractures was assault, followed by falls. The most frequently involved decade of age was between 20 and 29 years. The decision and type of surgical treatment of ZMC fractures depends on several issues that need to be considered on a case by case basis.

The "European Mandibular Angle" Research Project: The Epidemiologic Results From a Multicenter European Collaboration.

PURPOSE: The aim of this study was to analyze the demographic variables and causes and characteristics of mandibular angle fractures managed at several European departments of maxillofacial surgery. MATERIALS AND METHODS: This study was based on a multicenter systematic database that allowed the recording of data from all patients with mandibular angle fractures between January 1, 2013, and December 31, 2017. The following data were recorded: gender, age, etiology, side of angle fracture, associated mandibular fractures, presence of third molar, intermaxillary fixation, and osteosynthesis. RESULTS: The study included 1,162 patients (1,045 male and 117 female patients). A significant association was found between the presence of a third molar and the diagnosis of an isolated angle fracture (P < .0000005). Furthermore, assaults were associated with the presence of voluptuary habits (P < .00005), a younger mean age (P < .00000005), male gender (P < .00000005), and left-sided angle fractures (P < .00000005). CONCLUSIONS: Assaults and falls actually represent the most frequent causes of angle fractures. The presence of a third molar may let the force completely disperse during the determination of the angle fracture, finding a point of weakness.

Bacteremia Following Closed and Open Dental Extraction.

AIM: To observe bacteremia following closed and open dental extraction. MATERIAL AND METHODS: The study included two subject groups each comprising 29 participants. Group I patients received a single closed dental extraction, and group II patients ­ a single open extraction. Venous blood from the cubital vein of each patient was collected in three samples ­ preoperatively, 30 seconds after surgery, and 15 minutes after surgery. Anaerobic and aerobic hemocultures (Bact/ALERT, BioMerieux, Inc., Durhamn, N.C.) were used to study the bacteremia process. RESULTS: Preoperatively, bacteremia was confirmed in 4 patients (6.9%) undergoing closed extraction and in 1 patient (1.7%) undergoing open extraction. Additionally, we found statistically significant relation between bacteremia and age (p=0.002). Thirty seconds after surgery bacteriemia was evident in 6 patients (10.3%) from group I and in 3 (5.2%) from group II. Fifteen minutes following surgery bacteremia was evident in 4 patients (6.9%) undergoing typical extraction and in one patient (1.7%) undergoing surgical extraction. No statistically significant relation between type of extraction and presence of bacteria in the bloodstream at 30 seconds (p=0.285) and at 15 minutes (p=0.166) was found. Coagulase-negative Staphylococcus was the most frequently found microorganism (22.2% of aerobic and 11.1% of anaerobic hemocultures). The results show greater significance of bacteremia at 30 seconds, compared to preoperative samples for both subject groups (p=0.03). CONCLUSIONS: Bacteremia following dental extraction is unaffected by duration of intervention, type of extraction and gender.

Salivary creatinine and urea in patients with end-stage chronic kidney disease could not be used as diagnostic biomarkers for the effectiveness of dialysis treatment.

INTRODUCTION: End-stage chronic kidney disease (CKD) is characterized by kidney failure with the organ's functions reduced or lost completely, where the kidneys are incapable of filtering excess fluids. Renal replacement therapy may be provided by peritoneal dialysis, hemodialysis or renal transplantation. Among the key indicators for tracking patients' current status are urea and creatinine levels. AIM: The study analyzed saliva as a medium to detect and measure urea and creatinine levels in end-stage CKD patients as well as to use it as criteria for the effectiveness of the dialysis treatment by comparing salivary urea and creatinine levels with their blood levels. MATERIAL AND METHODS: The study targeted 70 end-stage CKD patients from northeastern Bulgaria undergoing hemodialysis treatment. The urea in blood serum was carried out using the UV kinetic method. Creatinine levels were measured using Jaffe reaction colorimetric method without deproteinezation, adapted on an Olympus AU 400 automated biochemical analyzer (Beckman Coulter Inc., USA). Samples from whole unstimulated saliva were collected in a 15 ml sterile test tube as per Navazesh method. The qualitative determination of salivary urea was performed using the UV kinetic method. Creatinine levels in whole unstimulated saliva were measured using Jaffe reaction colorimetric method. RESULTS: There was a statistically significant reduction in blood urea levels (P=0.000) and in blood creatinine levels (P = 0.000) following hemodialysis. The results revealed that there was no statistically significant dependence between both, the urea levels (P=0.240) and the creatinine levels (P=0.065) in whole unstimulated saliva obtained prior to and after a hemodialysis. CONCLUSIONS: Despite the parallel increase of the urea and creatinine levels in blood serum and in whole unstimulated saliva in end-stage CKD, salivary urea and creatinine levels could not be used as diagnostic biomarkers for the effectiveness of dialysis treatment.

Taste disorders in patients with end-stage chronic kidney disease.

The authors aimed to explore taste distortion in patients with chronic kidney disease (CKD). One hundred and four patients were divided into a control group and a study group. The data was collected through a questionnaire and was statistically analyzed. The results showed that 28.7% of respondents had a loss of taste (96.60% CKD patients). There was a statistically significant correlation between the duration of treatment and taste loss, between patients' age and taste impairment, and between patients' age and the sense of a metallic taste in the mouth. Distortion in the sense of taste is an oral manifestation characteristic of CKD patients.

Sagliker syndrome: first four cases in Bulgaria.

UNLABELLED: Sagliker syndrome characterized with uglifying the appearance of the face due to secondary hyperparathyroidism in patients with chronic renal failure receiving dialysis long time ago. The aim of the study was to identify any patients with Sagliker syndrome among the 78 patients receiving dialysis at the Dialysis ward, University Hospital "St. George", Plovdiv, Bulgaria. RESULTS: Four patients metthe criteria for Sagliker syndrome: chronic renal insufficiency, secondary hyperparathyroidism, short stature, severe changes in the skull and jaw that lead to festoon-like uglifying face, dental abnormalities, "brown" tumors, deformations of the phalanges of the fingers, psychological diseases and depression. CONCLUSION: The lack of control of the level of calcium and phosphorus in the blood in patients with chronic kidney disease leads to severe bone changes and psychological changes in patients with prolonged dialysis.