Zsolt Németh

Long-term results with different bone substitutes used for sinus floor elevation.

One of the surgical procedures preceding implantation is elevation of the base of the maxillary sinus. Numerous bone substituting materials (grafts) may be used for this purpose, including autogenous bone, heterografts, xenogenous bone, and synthetic materials alone or in combination or mixed with growth factors and bone morphogenetic protein (BMP) preparations. A study of the frequencies of the failures (graft material resorption or implant loss) after sinus elevations with various graft materials or their combinations was conducted. In the 5-year period from 1996 through 2001, a follow-up investigation of 810 maxillary sinus augmentations was performed, in which the sinus elevations involved the use of autogenous bone, a calcium carbonate-coated polymer, hydroxylapatite of algal origin, calcium carbonate gel produced from coral or &bgr;-tricalcium phosphate alone, autogenous bone mixed with these bone substitutes, or a combination of &bgr;-tricalcium phosphate and platelet-rich plasma. The incidences of graft resorption and implant loss after the augmentations with various bone substitutes were recorded. Total resorption (disappearance) of the bone substitute material was observed in 2.7% of the cases. An essential difference was not experienced between the various bone substitutes from this aspect, with the exception of the gel-state calcium carbonate, where 40% of the grafts were resorbed. In total, 5.46% of the implants were lost; the differences between the various materials were not significant.

Repair of bony defect with combination biomaterials.

BackgroundNumerous possibilities are available for the reconstruction of facial bone defects. The materials used to fill such defects must satisfy various requirements. One of the most important is that they must undergo transformation into autologous bone tissue in the process of remodeling. AimA report is given of the long-term results of augmentations of large bone defects performed with different bone-substitute materials in two patients. Patients and methodsIn one case, augmentation was carried out with &bgr;-tricalcium phosphate after the removal of a fibromyxoma. In the second case, three large cystic lesions in the mandible of a patient with Gorlin-Goltz syndrome were filled with &bgr;-tricalcium phosphate, with a mixture of &bgr;-tricalcium phosphate and platelet concentrate, or with hydroxyapatite of algal origin. The process of ossification was checked at 6-month intervals by means of clinical, radiologic (orthopantomograms and two-dimensional and three-dimensional computer tomograms), and histologic methods. ResultsAt 1 year after the intervention, the site of the augmentation was in all cases occupied by hard tissue of good quality. With the given imaging procedures, it was difficult to distinguish between the original bone and the region filled with bone-substitute material. The three-dimensional computer tomogram images indicated that the contours and quality of the new bone corresponded with the physiologic and anatomical conditions. The histologic examinations show the remodeling of the bone-substitute materials. DiscussionThe bone-substitute materials applied in these cases fully satisfied the demands of transformation into bone (remodeling). The speed of remodeling seemed to be the fastest when the mixture of &bgr;-tricalcium phosphate and platelet concentrate was used.

Possibilities of preventing osteoradionecrosis during complex therapy of Tumors of the oral cavity

In recent years, there has been a dramatic increase in the number of tumors of the head and neck. Their successful treatment is one of the greatest challenges for physicians dealing with oncotherapy. An organic part of the complex therapy is preoperative or post-operative irradiation. Application of this is accompanied by a lower risk of recurrences, and by a higher proportion of cured patients. Unfortunately, irradiation also has a disadvantage: the development of osteoradionecrosis, a special form of osteomyelitis, in some patients (mainly in those cases where irradiation occurs after bone resection or after partial removal of the periosteum). Once the clinical picture of this irradiation complication has developed, its treatment is very difficult. A significant result or complete freedom from complaints can be attained only rarely. Attention must therefore be focussed primarily on prevention, and the oral surgeon, the oncoradiologist and the patient too can all do much to help prevent the occurrence of osteoradionecrosis. Through coupling of an up-to-date, functional surgical attitude with knowledge relating to modern radiology and radiation physics, the way may be opened to forestall this complication that is so difficult to cure.

Atypical courses of the mandibular canal: Comparative examination of dry mandibles and x-rays

Knowledge of the course of the mandibular canal and its anatomic variations is of great importance in oral surgery, especially in preprosthetic operations and the insertion of endosteal implants and during the planning of removable dentures prepared in cases involving extensively atrophied mandibles. We review the literature on duplicated mandibular canals, which is based exclusively on radiologic findings. Then, we compare this with an examination of dry mandibles and further radiologic studies. The incidence of duplicated mandibular canals observed in macroscopic examinations of mandibles was substantially higher than that revealed by radiographs. One case involving a novel variation, a triple mandibular canal, is reported.

Titanium implants with oxidized surfaces: the background and long-term results

The purpose of this paper is to give an overview of different implant surface modification technologies?including the presentation of a new technique, involving the formation of a ceramic titanium oxide coating. Three techniques are used to modify metal surfaces: (1) addition of material, (2) removal of material and (3) modification of material already present, e.g. by means of laser or electron-beam thermal treatment. The new technique outlined in this paper relates to the production of a corrosion-resistant, 2000?2500 ? thick, ceramic oxide layer with a consistent crystalline structure on the surface of a titanium implant. The layer is grown electrochemically from the bulk of the metal and modified by heat treatment. Such ceramic oxide-coated implants have advantageous properties compared to implants covered with other coatings: a higher external hardness; a greater force of adhesion between the titanium and the ceramic oxide coating; virtually perfect insulation between an organism and a metal and therefore no possibility of triggering metal allergy. Plates and screws for maxillofacial osteosynthesis and dental root implants with ceramic oxide coatings were subjected to various physical, chemical and electron microscope tests for qualitative characterization, and have been applied in surgical practice over a period of 15 years. The mini-plates removed were examined for the possible surface alterations which may occur during the implantation period. The sites of the removal were inspected for metallosis, which is common when titanium mini-plates are used. The results obtained demonstrate the good properties of the ceramic oxide-coated implants.

False diagnosis caused by Warthin tumor of the parotid gland combined with actinomycosis.

A case is reported in which a unilateral parotid gland cystadenolymphoma was combined with actinomycosis. A 48-year-old woman presented with a mass in the left parotid region and paresis of the lower left palpebra. The computed tomography, echography, and parotid radiographic findings did not exclude a neoplasm of the left parotid gland. The ramus of the mandible was involved in the process. Intraoperative freezing histology, total parotidectomy, and partial mandibulectomy were performed, with sacrifice of the facial nerve followed by nerve reconstruction. The final histological evaluation was Warthin tumor with actinomycosis. Four years after treatment, the patient is free of disease. No similar cases seem to have been reported thus far.

Effect of induction chemotherapy on changes of laminin and syndecan expression in oral squamous cell carcinomas: a prospective, randomized, clinicopathologic and immunohistochemical study.

Sixty patients with tumors of the floor of the mouth or of the tongue (T2N0-1-2M0) were randomized into three treatment groups. The first two groups participated in low-dose inductive chemotherapy, surgery, and then radiotherapy, whereas the third control group underwent only surgery and radiotherapy. In all three groups, studies were made of the stage, grade, sex, localization, extents of expression of the pretreatment laminin and syndecan-1 and the cancer specific survival rate, and the correlations among these. The response to neoadjuvant chemotherapy was assessed by means of a method that we developed, involving measurement of the degree of histologic regression observed in response to chemotherapy. Immunohistochemical methods were applied to investigate the changes in degree of expression of laminin and syndecan-1 in response to the medication and their correlations with the survival. As concerns the overall tumorfree survival rate, a significant difference was not found between the two chemotherapeutic groups. However, there was a significant difference between the survival indices of those who participated in cytostatic treatment (70%) and the control group (40%). In the clinical and immunohistochemical examinations, the initial laminin and syndecan-1 levels obtained from biopsy samples could be used as prognostic factors. Our model measuring the extent of histologic regression clearly demonstrated that the survival indices of the patients who responded to the neoadjuvant cytostatic treatment with adequate tissue regression were better than those of the patients who responded to the treatment to only a decreased extent or not at all. The changes in the expressions of laminin and syndecan-1 in response to cystostatic treatment proved to be important predictive factors. The increase or stagnation of these clearly forecast a good prognosis, whereas their decrease was a definite indication of poor prognosis.

Comparison of postoperative complications following bone harvesting from two different donor sites for autologous bone replacement (hipbone and proximal epiphysis of the tibia)

Whereas autologous bone replacement was earlier applied in maxillofacial surgery virtually only for the restoration of mandibular defects and for the osteoplasty of patients with cleft alveolar process, the free transplantation of autologous bone (spongiosa or cortical bone or both) is nowadays primarily used for implantation purposes. Autologous bone is still the gold standard for bone replacement. This is the case even though a wide selection of bone substitutes is currently available, with which new bone equivalent to autologous bone can be produced in certain cases. Autologous bone is often obtained from intraoral sources, but if a larger quantity of spongiosa is required, these sites (the chin, the retromolar area of the mandible, the muscular process, etc.) are not suitable. Of the extraoral donor sites, the most frequently used site is the iliac crest, but the proximal epiphysis of the tibia is also appropriate for this purpose since we have recently performed bone transplantations on appreciable numbers of patients, we decided to compare the morbidity data relating to the two donor sites. In the 9 months between March and November 2007, sinus elevations were carried out on 14 patients with bone taken from the tibia, while in 38 patients bone was taken from the iliac crest for osteoplasty on clefted alveolar process. The comparison was based on postoperative clinical examinations, the complaints of the patients and objective study of the morbidity relating to the two donor sites. Clinically the patients tolerated both interventions well. Mobilization took place on the day of intervention. There were no major complications; one minor haematoma was observed after each type of surgery. The postoperative complaints of the patients did not reveal any essential difference. Following bone harvesting from the iliac crest, the gait of the patients slightly hampered for up to 10 to 14 days. In the tibia cases, the patients experienced no pain on walking by the second day. As regards donor site morbidity, protracted (1-2 weeks) oedema was observed after hip surgery, with paraesthesia of the area of innervation of the n. cutaneous femoris lateralis in 1 case, while there was a minor seroma following tibia surgery in 1 case. Our clinical experience suggests that, if 10-15 cm(3) spongiosa is required for augmentation purposes and there is no need for cortical bone, the patient is exposed to less stress when bone is taken from the proximal epiphysis of the tibia.

Overall survival of oropharyngeal cancer patients treated with different treatment modalities.

Therapeutic modalities of use in tumor therapy can be applied in various combinations to treat malignant lesions of the mesopharynx. A study was made of the overall survival of patients with mesopharyngeal carcinoma treated with different modalities in our institution in the period 1995-2000. In this retrospective study, a total of 66 patients were divided into 4 groups: Patients who took part in 1) intra-arterial chemotherapy and subsequent irradiation; 2) intra-arterial chemotherapy and surgical care; 3) only surgical care; or 4) only irradiation or palliative treatment. In each group, the five-year survival rate was examined, as a function of the age of the patient, the initial tumor size, the lymph node status and the clinical stage. The five-year overall survival rate in group 1 was 28.57%, in both group 2 and group 3 was 66.66%, and in group 4 was 20%. For all of the 66 patients, it was 43.93%. For groups 2 and 3, the Kendall rank correction test did not reveal a significant effect of the lymph node state or the clinical stage on the survival, whereas the effects of the age and the initial tumor size did prove to be significant. The Cox regression test showed the latter of these two effects to be the stronger. As 64 of the 66 patients examined were treated for tumors in clinical stages III or IV, the five-year survival rate of 43.93% may be said to be good. The comparison of groups 2 and 3 revealed that (in spite of the poorer initial prognosis in group 2) the survival rates were the same, i.e. the neoadjuvant intra-arterial chemotherapy improved the prognosis.

Carbon/carbon implants in the oral and maxillofacial surgery – Part 1

UNLABELLED Over the past 20-30 years various carbon implant materials have become more interesting, because they are well accepted by the biological environment. The traditional carbon-based polymers give rise to many complications. The polymer complication may be eliminated through carbon fibres bound by pyrocarbon (carbon/carbon). AIM The aim of this study is to present the long-term results of carbon/carbon implants. METHODS Mandibular reconstruction was performed with pure (99.99%) carbon implants in 16 patients. Predominantly tumorous cases were included (10 malignant tumors, 4 large cystic lesions and 2 augmentative processes). RESULTS Because the interventions had been performed 6-8 years before the last follow-up visit, the authors report long-term results. Of the 16 patients, the implants had to be removed earlier in 5 patients because of the defect that arose on the oral mucosa above the carbon plates. The most probable cause of this complication was the strain in the oral mucosa and disturbances in its blood supply (previous surgery, irradiated tissue, etc.). During the long-term follow-up, plate fracture, loosening of screws, infection or inflammation around the carbon/carbon implants were not observed. After 8 years one carbon implant was substituted with an autogenous bone. CONCLUSIONS The clinical conclusion is that if the soft part cover is appropriate, the carbon implants are cosmetically and functionally more suitable than titanium plates. The structural and chemical investigation of the removed implant will be published in the near future.