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Biomedical subjects

N Hardt

Publications and source records attributed to N Hardt.

At least 19 recordsLinked to original sources
PubMed2003

Long-term results following miniplate eminoplasty for the treatment of recurrent dislocation and habitual luxation of the temporomandibular joint.

Twenty patients with recurrent mandibular dislocation or habitual luxation of the temporomandibular joint who underwent miniplate eminoplasty between 1994 and 1999 are presented. The follow-up period ranged from 2 to 7 years. Clinical examination showed no evidence of recurrent dislocation. No significant reduction of normal mouth opening was found one year postoperatively. The pain level, self-estimated by the patients on a scale from 0 to 10, decreased significantly from 4.1 preoperatively to 1.2 one year postoperatively. In seven patients fractures of the miniplates occurred 3 to 7 years after eminioplasty (two bilateral fractures, five unilateral fractures). Due to the high incidence of plate fractures miniplate eminoplasty cannot be recommended as the surgical treatment of choice for recurrent dislocation or habitual luxation of the mandible, although the recurrence rate is low and pain is reduced considerably.

Adult↗
PubMed2002

[Juvenile ossifying fibroma. Case report with diagnostic and therapeutic considerations].

BACKGROUND: Fibro-osseous lesions of the jaws, including juvenile ossifying fibroma, pose diagnostic and therapeutic difficulties due to their clinical, radiological and histological variability. CASE REPORT: The case of an 8-year-old girl with a juvenile ossifying fibroma of the mandible is presented. Extirpation of the tumor and filling of the defect with cancellous bone was performed. After 9 months, a recurrence occurred which made a second extirpation of the tumor necessary. This was done without osteoplasty. After a 2-year follow-up the patient is free of tumor. DISCUSSION: Different classifications for fibro-osseous lesions of the jaws can be found in the literature. This makes a correct diagnosis and standardized treatment difficult. Based on the case presented here, the histological features of juvenile ossifying fibroma and the differentiation from osteosarcoma are discussed. At present, conservative surgical treatment seems to be adequate for these tumors.

Bone Transplantation↗
PubMed2002

Dynamic simulation of chemical industry wastewater treatment plants.

High variability, stringent effluent permits, and often extreme operating conditions define the practice of wastewater treatment in the chemical industry. This paper reviews the benefits and challenges of applying dynamic simulation to chemical-industry wastewater treatment plants by describing case studies at full-scale wastewater treatment plants (WWTP). The applications range from process troubleshooting to optimization and control. The applications have been valuable and useful in developing a deeper understanding of the plants as integrated systems. However there still remains substantial work to implement the dynamic simulations for daily real-time use by plant engineers and operators. This opportunity to improve plant operations is still largely untapped and will remain so until dynamic state estimation and data reconciliation are incorporated into simulation packages for use in developing the on-line simulations.

Bioreactors↗
PubMed2001

Periradicular surgery of molars: a prospective clinical study with a one-year follow-up.

AIM: The purpose of this prospective clinical study was to evaluate the outcome of periradicular surgery of molars after one year. METHODOLOGY: The material consisted of 25 molars with 39 roots demonstrating periradicular lesions of endodontic origin. Surgical treatment included root-end resection, root-end preparation with sonic microtips, and root-end filling with Super-EBA cement. At the one-year follow-up examination, healing was evaluated clinically and radiographically. Healing was assigned to three categories: (i) success (ii) improvement, and (iii) failure using well defined criteria. RESULTS: Eighty-eight per cent of the surgically treated molars showed successful healing. In 8%, the healing was rated as improved and only 4% were failures. CONCLUSIONS: The outcome of the present study and data of recently published studies show that periradicular surgery may result in a predictable treatment outcome in molars with persistent periradicular lesions.

Adult↗
PubMed2001

Long-term results following reconstruction of craniofacial defects with titanium micro-mesh systems.

Introduction: Reconstruction of craniofacial defects can be carried out with autogenous tissue (calvarium, rib, iliac crest), allogeneic implants (AAA-bone, lyophilized cartilage) or alloplastic material (methacrylate, hydroxyapatite, titanium implants and mesh systems). Selection of the implant material used for reconstruction is still controversial. Material and Methods: At the Department of Oral and Maxillofacial Surgery, Kantonsspital Luzern, 20 patients with defects in the craniofacial and/or orbito-ethmoidal region have been treated using titanium micro-mesh between 1991 and 1998. Two different mesh systems, micro-titanium augmentation mesh and dynamic mesh, have been used for bony reconstruction in non load-bearing areas. The defects were caused by acute trauma, osteomyelitis of the frontal bone and previous operations. The titanium micro-mesh was used with the following indications: (1) immediate reconstruction in the primary treatment of comminuted fractures with bone loss in non load-bearing areas, (2) treatment of contour irregularities (possibly in combination with bone or cartilage grafts). All patients were followed up clinically and radiographically at quarterly intervals for a year. Results: No wound infections, exposures or loss of the mesh have been observed. Long-term stability of the reconstructions was excellent. When walls of the paranasal sinuses were reconstructed complete repneumatisation took place. Conclusions: Advantages of this reconstructive technique are: (1) universal applicability (craniofacial, orbital, sinus defects, comminuted fractures); (2) stable 3-D reconstruction of complex anatomic structures were easily performed; (3) immediate availability with no donor site morbidity as bone or cartilage grafts were not necessary; (4) combination with bone or cartilage grafts is possible; and (5) very low susceptibility to infection. Copyright 2001 European Association for Cranio-Maxillofacial Surgery.

Journal Article↗
PubMed1998

[Results of transcranial and subcranial management of fractures of the naso-ethmoid-orbital system in complex midfacial fractures].

Injuries of the nasoethmoid-orbital (NEO) region are associated with midfacial fractures or fractures of the frontobase in over 90% of all cases. In up to 70% fractures of the skull base run through the roof of the ethmoidal bone or the lamina cribrosa. There are different surgical approaches for the treatment of these complex fractures. Between 1990 and 1997 50 patients with midfacial fractures in association with NEO fractures were treated in the Klinik für Mund-, Kiefer- und Gesichtschirurgie, Kantonsspital Luzern, Switzerland. Of these, 25 had suffered midfacial fractures combined with fractures of the nasoethmoid-orbital and frontobasal region and were treated via a transcranial approach. The other 25 patients with midfacial and NEO fractures without involvement of the frontobasis were managed by subcranial incisions. A total of 47 patients were followed up for up to 4 years. The results were reevaluated retrospectively. There was no case of secondary liquorrhea, intracranial or ethmoidal infection. Our therapeutic concept of transcranial and subcranial management of NEO fractures in combination with frontobasal and midfacial fractures is demonstrated.

Adolescent↗
PubMed1998

Localized ridge augmentation using a micro titanium mesh: a report on 27 implants followed from 1 to 3 years after functional loading.

The present paper describes the clinical and radiographic healing results of 27 implants followed from 1 to 3 years after functional implant loading. Prior to implant placement, alveolar ridges with insufficient bone volume were augmented using autogenous bone grafts and a micro titanium mesh for graft stabilization. After a mean interval of 5.2 months implants were installed. Following an osseointegration period of on average 7.2 months, implants were supplied with suprastructures. The mean loading period for the 27 implants was 21 months. All implants exhibited ankylotic stability and healthy peri-implant soft tissues. The detailed analysis of clinical parameters (probing depth, level of mucosal margin, attachment level, modified plaque and sulcus bleeding indices) and radiographic measurements (crestal bone level), revealed findings similar to those at implants placed into non-augmented bone. Peri-implant bone resorption was calculated to be 1.0 mm for the 1st year after implant loading and 0.1 mm for the following year. Pain, suppuration or semilunar bone defects were absent at all implants. It was concluded that loaded dental implants which have been inserted into an augmented alveolar ridge using autogenous bone grafts and a micro titanium mesh for graft stabilization, demonstrate clinical and radiographic findings similar to those of implants placed into a pristine ridge.

Adult↗
PubMed1998

Preliminary results and analysis of a new set of sonic instruments for root-end cavity preparation.

The introduction of microinstruments for root-end cavity preparation has clearly improved the surgical technique in periradicular surgery with apicectomy. The new generation of sonic and ultrasonic root-end preparation devices, usually termed 'retrotips', has simplified the preparation of a sufficiently deep cavity that follows the original path of the root canal. The present paper describes the use of a new set of diamond-surfaced retrotips driven by a sonic handpiece. For clinical evaluation a prospective study was carried out, with assessment of pre-, intra- and postoperative data in 50 teeth (43 patients). This paper analyses: (i) the applicability of the new retrotips; (ii) the quality of the root-end filling assessed radiographically; (iii) the immediate postoperative course. Access with the retrotips to the resected root-end was found to be excellent in 80% of the treated teeth. The postoperative radiographs showed a root-end filling of at least 3 mm in 70% of the resected teeth. Healing was uneventful in all cases and most patients presented without any symptoms after 5 days and 10 days. The long-term treatment outcome will be reported in a future paper.

Adolescent↗
PubMed1997

[Synovial chondromatosis of the temporomandibular joint with invasion into the middle cranial fossa].

Synovial chondromatosis of the temporomandibular joint is a rare occurrence. Resorption of the floor of the skull base caused by the tumour with invasion into the middle cranial fossa has only been described a few times. We report on diagnosis, histologic examination and therapy of a patient with synovial chondromatosis in the articular tubercle of the right temporomandibular joint invading the middle and cranial fossa. After tumour exstirpation the defect in the floor of the middle cranial fossa was reconstructed using a split-skull graft via an intracranial approach.

Adult↗
PubMed1997

Results of a modified staircase technique for reconstruction of the lower lip.

Our experience with a modified staircase technique for closure of lower lip defects is reported. The procedure is based on the original technique of Johanson et al. (1974). However, the integrity of the orbicularis oris muscle is respected when advancing lower lip flaps. Twenty patients with squamous cell carcinoma of the lower lip were treated using this modified reconstruction technique. The size of the defects ranged from 30-60% of lower lip width. No recurrences were observed during a 3-year to 5-year follow-up. All patients showed symmetrical lip movement, an adequate buccal sulcus and intact labial commissures. No symptomatic microstomia was seen and the aesthetic results were excellent. The surgical technique is explained in detail. Four types of flap are presented according to the size and location of lip defects. Lower lip defects up to 60% of the lip width can be closed easily, with good aesthetic results. The technique is also applicable to upper lip reconstruction.

Carcinoma, Squamous Cell↗
PubMed1997

Treatment of severe peri-implant bone loss using autogenous bone and a resorbable membrane. Case report and literature review.

Clinical case reports and animal studies have demonstrated that the principle of guided bone regeneration can be applied for surgical treatment of moderate to profound peri-implant bone loss (peri-implantitis). However, the degree of bone regeneration within the peri-implant osseous defect was reported to be variable depending on different clinical factors and on the postoperative course. Most papers dealing with surgical treatment of peri-implantitis advocate the use of a non-resorbable ePTFE membrane for secluding the peri-implant bone defect enabling bone regeneration. Additionally some surgeons fill the defects with allografts or alloplasts. The present case report demonstrates another surgical approach by using autogenous cancellous bone for grafting into the peri-implant bone defect and placing a bioresorbable polylactide membrane as a matrix barrier. The successful outcome of this modified surgical approach enabled the patient to maintain the implant for prosthetic reconstruction after early but severe bone loss.

Absorption↗
PubMed1996

The use of micro-titanium mesh for maxillary sinus wall reconstruction.

Operations on the maxillary sinus can lead to extensive bony defects of the facial and laterodorsal walls of the sinus. If there is no autogenous bone material available, the problem is to find a suitable substitute for reconstruction. We examined the suitability of micro-titanium mesh for reconstruction of the walls of the maxillary sinus. In 13 adult patients large defects of the walls of the maxillary sinus were reconstructed using micro-titanium mesh. Indications for operation were tumours, large dental-type cysts, traumatic bone loss and chronic inflammation in sinuses which had been previously operated on. Clinical and radiological examinations were carried out immediately after surgery and after a 3 months interval. Control by sinuscopy was performed in all patients. Great importance was attached to the following aspects: 1. correctly shaped reconstruction of the maxillary sinus 2. prevention of soft tissue prolapse into the sinus 3. aeration of the maxillary sinus 4. preservation of the facial contour

Adolescent↗
PubMed1996

[Results of follow-up of temporomandibular joint fractures in 30 children].

Disturbances of facial growth and occlusion as well as temporomandibular joint dysfunction are possible sequelae of temporomandibular joint fractures in children. In a follow-up study we examined 30 children with conservatively treated condylar fractures of the mandible (age at time of accident from 9 months to 13 years) regarding dysfunction or growth disturbances within the stomatognathic system. The mean interval between the accident and the follow-up was 4 years and 11 months. We found 6 cases with tilted occlusional planes in the 'en face' analysis, 3 of them with bilateral condylar fractures. There was only one case with a facial asymmetry. The interincisive distance was never below 35 mm. Only 3 patients, all of them with bilateral condylar fractures, had a restricted mobility of the mandible. Remodelling of the condylar head was good in 92% of the cases. Two patients with bilateral fractures showed formation of a bifid condyle without ankylosis. Deviation of the ascending ramus in the horizontal plane was observed radiographically in 21% of the cases with unilateral fractures and in 33% with bilateral fractures respectively and always in a medial direction. Measurement of the length of the Processus articularis in the orthopantomogramm showed a shortening in 70% of the cases on the fracture side. The radiographic evaluation of facial asymmetry after Ricketts and Mulick only revealed an angle difference of more than 5 degrees in some cases.

Adolescent↗
PubMed1995

[Effect and sequelae of supernumerary tooth in the premaxilla].

Although uncommon, anterior maxillary supernumerary teeth (mesiodentes) are the most frequent supernumerary teeth. A disturbed or delayed eruption of the adjacent permanent incisors may be due to a mesiodens and should lead to a further radiographic examination. In some cases the exact radiographic location of the mesiodens may prove difficult. The surgical removal of mesiodentes is especially difficult in extreme cranial displacement. The records of 90 patients with 113 mesiodentes are discussed with special reference to their degree of retention, topographical location, width of pericoronal space and surgical removal, and incidence of retention and malposition of the adjacent permanent incisors, respectively.

Adolescent↗