Biomedical subjects

G Santler

Publications and source records attributed to G Santler.

At least 19 recordsLinked to original sources

PubMed2002

Analysis of midface asymmetry in patients with cleft lip, alveolus and palate at the age of 3 months using 3D-COSMOS measuring system.

INTRODUCTION: Patients suffering from unilateral cleft lip, alveolus and palate exhibit a varying degree of asymmetry of the midface. Evaluation of this asymmetry can be carried out by means of 3D-CT, or a laser surface scanner. MATERIAL AND METHODS: In this paper, 3D-CT-scan data of 21 patients with unilateral clefts of lip, alveolus and palate were analysed using three-dimensional models. Evaluations of the 3D-models were carried out with the computer-aided 3D-operation simulator 3D-Cosmos. RESULTS: Asymmetry was found in the orbital, nasal and maxillary regions. The infraorbital rims were displaced craniocaudally and horizontally as well as laterally of the cleft-sided piriform aperture. This asymmetry corresponded to a dislocation of the maxillary segment on the cleft side. A deficit in volume was not reliably found.

Alveolar Process↗

PubMed2001

Computer assisted tumour resection of the skull base: case report.

This case report demonstrates computer assisted resection of a skull base tumour after combined chemotherapy and irradiation, in a 40-year-old man with a squamous cell carcinoma of maxilla, zygoma, orbit and skull base. The resection of the skull base was performed with computer assistance after conventional resection of the maxilla, midface, exenteration of the orbit and lymph node dissection. Following combined chemotherapy and irradiation, the original, pretherapeutic tumour extent was marked on the new, presurgical CT scan enabling resection of the skull base with the use of a navigation microscope. Thus planned resection from the presurgical CT could be transposed intraoperatively using the navigation system, and the skull base could be resected with precision.

Adult↗

PubMed2000

Three-dimensional planning of alveolar ridge distraction by means of distraction implants.

OBJECTIVE: In recent years, three-dimensional (3D) CT-based planning methods have increasingly been implemented in oral and maxillofacial surgery. Alveolar ridge distraction is accomplished by unidirectional distraction devices which in turn must be positioned optimally in all three dimensions. It is the aim of this study to demonstrate 3D planning of alveolar ridge distraction by means of distraction implants. PATIENTS AND METHODS: In 1997, nine patients were treated with distraction implants for a deficient alveolar ridge. A CT-scan-based 3D milled model of the facial skull was prepared for each patient to enable preoperative diagnosis and operative planning. RESULTS: Exact preoperative diagnosis of the alveolar ridge defect and atrophy was enabled by the 3D polyurethane model. Correct positioning of the distraction implants and predictability of the course of distraction was facilitated by preoperative planning according to the 3D model. CONCLUSION: Three-dimensional planning according to a milled model is an indispensable aid to positioning of distraction implants and therefore to directed augmentation of the alveolar ridge. Correct distractor positioning is vital for optimal subsequent prosthetic treatment.

Adult↗

PubMed2000

[Computerised three-dimensional surgical simulator. Introduction and precision analysis of a new system].

Computed tomography (CT)-based anatomic three-dimensional (3D) models have become important tools in oral maxillofacial surgery. There are three problems involved in the precise transfer of the experience gained and the results of simulation surgery to the patient: (1) 3D models have no precise reference points; (2) it is difficult to measure translations three-dimensionally; and (3) exact transfer to the patient intraoperatively is impossible. We have introduced a new system which solves these problems. In the first step 3D dental arches are replaced by plaster models, using an occlusal device with three radioopaque hemispheres as reference. A computerised electromagnetic tracker makes 3D measurements possible during simulated surgery, and a newly developed transfer system with a neurosurgical head frame to provide stable anchorage is used for positioning during surgery. We present our experience with this system in 15 orthognathic patients undergoing bimaxillary surgery. With the 3D computerised simulation surgery and model operation transfer system (3D-COSMOS) the dental arches can be replaced with a mean accuracy of 0.03 mm. The 3D translations of jaw segments can be measured precisely (0.11 mm) and simultaneously at the osteotomy line and the teeth. The new jaw position is transferred mechanically with a precision of 0.05 mm. Operation time is prolonged only by 15 min.

Cephalometry↗

PubMed2000

An analysis of 58 traumatically intruded and surgically extruded permanent teeth.

Fifty-eight traumatically intruded and mainly surgically extruded permanent teeth were followed up for 3 years and 4 months (mid-term results: 29 teeth) and 9 months (short-term results: 29 teeth) on average. Statistically, the mid-term results showed more cases of severe crown discoloration (54%) than the short-term results (9%), but no difference in pulpal and periodontal healing. Three teeth (5%) were lost. Factors which positively influenced pulpal healing were shallow intrusion depth, intact crown and immaturity of the root. Factors which positively influenced periodontal healing were shallow intrusion depth and minimal surgical manipulation. Alveolar bone healing was positively influenced only by shallow intrusion depth.

Adolescent↗

PubMed2000

Review of severe osteoradionecrosis treated by surgery alone or surgery with postoperative hyperbaric oxygenation.

We reviewed 41 patients with osteoradionecrosis of the mandible. Each patient was treated by radical resection followed by external beam irradiation. The diagnosis of infected osteoradionecrosis was confirmed clinically, radiologically, and histologically. After operation had failed, 20/41 were given hyperbaric oxygen (HBO) as in 'salvage' treatment. Daily sessions of HBO 2.5 ATA for 60 minutes (mean: 29 sessions) were given. The other 21 patients were treated by operation and antibiotics alone. HBO group (n = 20): The overall success rate for HBO after operation had failed was 13/20. Repeated debridement as first-line treatment followed by postoperative HBO was successful in 12/19. In seven of 19 patients, partial mandibulectomy and microvascular transplantation were required as second-line treatment, and this was successful in five. Primary partial mandibulectomy and microvascular transplantation followed by HBO was successful in 1 patient. Non-HBO group (n = 21): Repeated debridement was successful in 10/11 patients. Partial mandibulectomy was required as second-line treatment in the remaining one. In the other 10, partial mandibulectomy and microvascular transplantation were successful as first-line treatment in four. In the remaining six, further surgical intervention became necessary and were successful for 5-17 months (mean: 13). With a success rate of 13/20, we do not recommend HBO for the treatment of osteoradionecrosis.

Aged↗

PubMed2000

3-D COSMOS: a new 3-D model based computerised operation simulation and navigation system.

A new three-dimensional (3-D) model based system for preoperative planning, simulating the operation and transfer of the operation from 3-D model to patient (navigation) is to be introduced. A computer controlled digitizer with specially designed software enables 3-D measurement and symmetry analysis on the 3-D model with a precision better than 0.01 mm (SD: 0.05 mm, range: -0.2 to +0.04 mm). Translocations of the jaws during simulation are electronically registered with 6D-position sensors and displayed graphically and numerically on the PC screen (measurement accuracy 0.01 mm, 0.002 degrees). A precise transfer of positional data from the model to the patient in the operating theater is necessary if 3-D model operations are to be made. The position transfer (navigation) system to be introduced depends on a neurosurgical headframe on the patient, enabling an easy and three-dimensionally precise transfer of the planned jaw position to the patient. The three-dimensional precision of the positional transfer is 0.05 mm (SD: 0.144 mm, range: -0.36 to +0.69 mm). This new method allows for the first time exact three-dimensional simulation of operation and precise transfer to the patient. Especially in the case of asymmetric malformation and complex dysgnathia, the new method facilitates optimal symmetric and aesthetic results.

Computer Graphics↗

PubMed1999

Fabricating auricular prostheses using three-dimensional soft tissue models.

This article describes a method for fabricating an auricular prosthesis. This procedure uses the contours of the soft tissue surface from computerized tomography scans to fabricate a computer-generated, side-inverted 3-dimensional soft tissue model from a solid block of polyurethane using an Endoplan milling machine. The resultant 3-dimensional soft tissue model can then be used as the basis for a wax sculpture. This procedure facilitates the planning of the prosthesis; symmetrical modeling, especially for large, hemifacial defects; and the impression, which can be made on the model itself.

Acrylic Resins↗

PubMed1999

Fractures of the condylar process: surgical versus nonsurgical treatment.

PURPOSE: The purpose of this study was to compare outcomes from surgical and nonsurgical treatment of condylar process fractures. PATIENTS AND METHODS: Two hundred thirty-four patients with fractures of the mandibular condylar process were treated by open or closed methods. In the follow-up study, 150 patients with a mean follow-up time of 2.5 years were analyzed using radiologic and objective and subjective clinical examinations. RESULTS: No significant difference in mobility, joint problems, occlusion, muscle pain, or nerve disorders were observed when the surgically and nonsurgically treated patients were compared. The only significant difference was in subjective discomfort. Surgically treated patients showed significantly more weather sensitivity and pain on maximum mouth opening. CONCLUSION: Because of its disadvantages, open surgery is only indicated in patients with severely dislocated condylar process fractures.

Adolescent↗

PubMed1999

Clinical and magnetic resonance findings in the temporomandibular joints of patients before and after orthognathic surgery.

It is difficult to achieve the correct position of the condyle in the temporal fossa during orthognathic surgery in angle class II patients with disorders of the temporomandibular joint. This led us to examine the TMJ of 25 of our own patients before and shortly after orthognathic operations. We recorded the clinical and magnetic resonance imaging findings of the temporomandibular joint preoperatively and three months postoperatively. The patients had skeletal class II dysgnathia and had been treated with fixed orthodontic appliances for a mean of two years and three months before operation. Operation resulted in a mean reduction of maximal incisor distance of 12 mm. In five of the 25 patients, the pattern of mouth-opening changed. Nine patients had less pain than before surgery, and nine had fewer abnormal joint sounds. The magnetic resonance imaging showed displacement of the articular disc in 38 of the 50 joints preoperatively and in 28 postoperatively. Degenerative joint changes were not improved by operation. Improvement of the disc position was achieved by repositioning of the condylar-disc complex during orthognathic surgery in angle class II patients. Clinical and magnetic resonance imaging findings regarding the temporomandibular joint in class II patients correlated significantly both preoperatively and postoperatively.

Adult↗

PubMed1998

Advantage of three-dimensional models in intraoral callus distraction.

Distraction osteogenesis has become an important method of reconstructing hypoplastic facial bones. Intraoral callus distraction is a great aesthetic improvement, because no visible scars are caused. Precise preoperative planning is necessary, however, because the direction of distraction cannot be influenced postoperatively. Nine three-dimensional (3-D) models were used in three intraoral distraction cases: two patients suffered from unilateral hemifacial microsomia and one from micrognathia after bilateral ankylosis caused by multifocal osteomyelitis in childhood. In each case, models of the head were produced and the distraction was simulated preoperatively. The amount of distraction was 18 mm in the two hemifacial microsomia patients and 18 and 14 mm in the ankylosis case. Extension of distraction in the ankylosis patient was shorter on one side in order to achieve a correct midline position. A slight overcorrection of 3-5 mm was allowed to cover relapse and unpredictable future growth deficiency. Three-dimensional models can supply important information when employed in intraoral callus distraction. They allow anticipation of pitfalls and help to achieve a foreseeable result. Further advantages may be expected with complete 3-D enoral distraction in the future.

Child↗

PubMed1998

Stereolithography versus milled three-dimensional models: comparison of production method, indication, and accuracy.

Computed tomography (CT) based three-dimensional (3-D) lifelike models have proved to be of great value, especially in craniomaxillofacial surgery. They improve and facilitate diagnosis, therapeutic planning, model operations, and definitive treatment in tumor surgery, traumatology, dysgnathia, alveolar atrophy, and congenital and asymmetrical malformations. From 1988 to 1998, 760 stereolithography (STL) and milled 3-D models were employed in our department. These two production methods have become the msot commonly used approaches, and the question as to which is preferable is the subject of controversy in the literature. Using two test models the STL and the milling method were compared with regard to production method and accuracy, and the resulting differences in indications for their use are discussed. The limiting factor for increased accuracy is the distance between each pair of CT scans. Milled models show a higher precision compared to STL models within the CT-scan plane, but the more the measurements deviate from this plane (becoming oblique) the more inaccurate the data becomes. STL exhibits greater deviations, but the inaccuracy is randomly distributed. The mean variation from the original was 0.81 mm for STL and 0.54 mm for milled models. Although 90% of the milled and 80% of the STL values are within a deviation of +/- 1 mm, it should be noted that maximum deviations of 3.15 mm in milled models and 2 mm in STL have been shown. Both methods are sufficiently accurate for clinical use. In standard cases involving the upper and lower jaw, malar bone, orbita, and calvaria the shorter production time and lower costs make milled models preferable. In special cases, in which hollows and fine structures play a major role (e.g., those involving the skull base, paranasal sinuses, inner ear, and mandibular canal), STL is indicated.

Computer Simulation↗

PubMed1998

[Stereolithography models vs. milled 3D models. Production, indications, accuracy].

Anatomic, life-like, three-dimensional models have a definite place in cranio-maxillofacial surgery. Our experience with 541 computer tomographic (CT)-based three-dimensional (3D)-models for diagnostic purposes, preoperative planning and model operations in our department was gained using stereolithographic and milled models. The question of which production method is preferable is a matter of controversy in the literature. Both methods are based on CT and magnetic resonance imaging data, but the differences in production give rise to specific advantages and disadvantages. For comparison we scanned two measurement models, fabricated milled and stereolithographic models, and analyzed the differences concerning accuracy and shape of specific structures. The scan distance (feed) is the limiting factor for the accuracy for both methods. Milled models show the highest precision in the plane of CT scanning--the more oblique the measurements became to this plane, the greater the decrease in accuracy. Hollows and undercuts can only be produced by splitting the model. Stereolithographic models show higher deviations with randomly distributed errors. The mean deviation was 0.81 mm on stereolithography and 0.54 mm on milled models. The accuracy of both methods is sufficient for clinical use. In routine cases the milling method seems to be superior because of shorter production time and lower costs. In special cases, where hollows and fine structures play a major role, stereolithography is the method of choice.

Humans↗

PubMed1998

Application of combined three-dimensional bone and soft tissue model. A case report.

This article describes a new application in three-dimensional modelling. By adding the contours of important soft tissue structures to the bone contours, it is possible to produce a combined bone and soft tissue model. The advantages of this technique are shown in a patient suffering from a parapharyngeal tumour. The model not only enabled the precise localisation of the tumour in relation to the surrounding bone, but also identified important structures like the internal carotid artery in relation to the tumour.

Adult↗

PubMed1998

The Graz hemisphere splint: a new precise, non-invasive method of replacing the dental arch of 3D-models by plaster models.

Three-dimensional (3-D) anatomical models have proven their great value in the field of cranio-maxillofacial surgery. One major disadvantage is the limited representation of the teeth in milled and stereolithographic models. This is mainly caused by the limited resolution of the CT-scan, especially in the plane perpendicular to that of the scan. A new, precise, non-invasive and standardized method of replacing teeth of 3-D models by plaster models is introduced. The accuracy of tooth replacement is analysed. A plastic human skull is scanned with different interscan distances (scan feed), eight 3-D models are fabricated from this data and the positioning precision of the replaced plaster models in the three main axes is examined. Statistical analysis is carried out with a paired samples t-test. A mean positioning deviation of 0.44 and 0.52 mm in all directions is found using a CT feed of 2 and 3 mm. With 4 and 6 mm, the accuracy decreases showing 0.95 mm and 1.08 mm deviation. No significant difference is found between 2 mm and 3 mm scans, but significant differences between 2, 3 mm and 4, 6 mm are found. For the replacement of model teeth, at least three definitive fixed marks are required. With the aid of a hemisphere, used as a marker, the limited resolution in z-direction is overcome. The hemisphere is visible on several scans as semicircles of varying size. In the 3-D model, it allows precise positioning even on the z-axis enabling the exact replacement of teeth for the first time. A scan feed of 3 mm is sufficient for precise tooth replacement.

Calcium Sulfate↗

PubMed1998

Indications and limitations of three-dimensional models in cranio-maxillofacial surgery.

Anatomical, life-like, three-dimensional (3D) models have a definite place in cranio-maxillofacial surgery. Our experience with 541 computer tomography (CT)-based 3D models employed in aiding corrective surgery of tumours, dysgnathia, traumatology, alveolar atrophy, congenital malformation and asymmetrical malformations in our department is discussed. From July 1988 to February 1997, 3D models of 346 patients were used. Most of these were produced at our clinic. The indications, advantages and limitations of 3D-models were analysed retrospectively. In the case of congenital malformations (n = 60), models facilitated precise diagnosis of the skeletal deformity. Simulation surgery allowed prediction and solution of intraoperative problems prior to the actual patient operation. Size, shape and localization of defects caused by trauma (n = 64), osteoradionecrosis (n = 17) or osteomyelitis (n = 2) determined the choice of transplant donor site. In patients suffering from dysgnathia (n = 144), 3D models enabled exact positioning of the jaws. Precise planning could only be accomplished with the help of 3D models, especially for asymmetrical malformations (n = 12). In cases of severe atrophy of the alveolar crest (n = 45), exact measurement of the bone was possible and facilitated the decision as to whether dental implants, bone transplants or a combination of these were indicated. The positioning of transplants and implants was carried out in the ideal relation to the opposite jaw. In tumour patients (n = 186), it is not always possible to identify the tumour borders precisely on the CT scan or 3D model. Therefore, the defect was assumed to be bigger, a longer bridging plate constructed and this measurement corrected according to the intraoperative situation. The advantage of the 3D models consisted of an accurate representation of anatomical structures, bone or soft tissue. This allows precise preoperative diagnosis, operation planning and model operations. Due to this, the correct approach as well as operation technique could be chosen, outcomes of constant high quality were achieved, and there was a reduction in operation time.

Adolescent↗

PubMed1998

Treatment planning for sinus lift augmentations through use of 3-dimensional milled models derived from computed tomography scans: a report of 3 cases.

OBJECTIVE: Three-dimensional models created by milling machines and stereolithography on the basis of 3-dimensional computed tomography scans have become essential in the diagnosis and therapy planning of oral and maxillofacial disorders. The purpose of this study, based on 3 clinical cases, was to examine the advantages of using 3-dimensional computed tomography scans and 3-dimensional milling models of the maxillary sinus before operative sinus elevation and of developing an operative layout with the aid of 3-dimensional models. REPORT DESIGN: Three patients with atrophy of the maxillary alveolar ridge received computed tomography scans before operative sinus elevation with iliac bone transplants and simultaneous dental implantation. These computed tomography data were used to create 3-dimensional graphic and plastic reconstructions of the maxillary sinuses. RESULTS: The 3-dimensional milling models enabled the development of an exact preoperative layout that took into consideration the exact shape of the iliac bone and the selection of dental screw implants. Furthermore, the models offered the possibility of producing an acrylic device for precise implant insertion. Precise planning resulted in good success with implantation 2 years after surgery. CONCLUSION: Three-dimensional diagnosis and treatment layout have become an acknowledge method of operative maxillary sinus floor augmentation combined with simultaneous dental implantation in the upper jaw in difficult cases of sinus lift operations. As far as transplant shape and sinus anatomy are concerned, this has resulted in greater intraoperative precision. A 1-step procedure can thus be performed for augmentation and implantation through use of a well-adapted block transplant and dental screw implants in patients with extensive alveolar ridge atrophy.

Alveolar Bone Loss↗

PubMed1994

[Criteria for selecting the donor region in microsurgical reconstruction of bone defects in the area of the mouth, jaw and face].

In the time between October 1985 and April 1993 96 free vascularized bone transplantation were performed. We used iliac crest, scapular and rib grafts. The decision which donor site to use depends on several things. The pedicle of the transplant must be long at recipient sites like calvarium or upper jaw. In the lower jaw a long pedicle is needed only in cases one has to connect the vessels on the contralateral side. Scapula pedicled at the thoracodorsal artery with its long vessels is superior in these cases. Bone quality and soft tissue coverage have a great influence on the decision too. Localisation of the defect and position of the recipient vessels are the most important criteria in the choice of the donor site. So we suggest first to do the preparation of the defect and the recipient vessels and then decide the donor site.

Adolescent↗