Hans Kärcher

Scanning electron microscopical analysis of laser-treated titanium implant surfaces—a comparative study

Design and surface qualities of titanium implants are of vital importance for long-term stability following implantation. Four different implant surfaces treated individually were analyzed with special attention focused on laser surface treatment. Surfaces with machine roughness, titanium spray coating, treated by aluminum oxide and treated by laser were examined individually. Evaluation of the surface was carried out by electron microscope examination and mechanical profilometry. The EDS analysis determined the degree of contamination of the implant surface. Electron microscope examination showed that the titanium plasma spray as well as the laser-treated implants have optimum surface qualities: a secondary and tertiary structure with micro-roughness of 10 mm and roughness ranging from 0.5 to 4 mm. The least contamination was found for machine rough surfaces as well as those treated by laser. The other implants showed contamination corresponding to the method of surface treatment. In summary the optimal surface structure with the least contamination was found for the laser-treated titanium surface. Similar surface purity was found for the machine rough surfaces. An optimal structure was also achieved by the titanium plasma spray method, however, at the cost of surface purity.

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.

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.

Changes in soft tissue profile after sagittal split ramus osteotomy and retropositioning of the mandible

PURPOSE The prediction of profile changes as a result of orthognathic surgery remains a problem during preoperative planning because of the different relative movements of the hard and soft tissues. This study analyzed the changes in soft tissue profile after sagittal split ramus osteotomy and mandibular setback. PATIENTS AND METHODS Soft tissue changes relative to hard tissue references were recorded by means of computer-supported measurements of preoperative and postoperative standardized lateral skull radiographs of 60 Class III patients. RESULTS An average backward transposition of the osseous pogonion of 7.1 mm was recorded. Relative to movements of this reference point in the sagittal plane, the soft tissue pogonion moved 83.9%, the soft tissue menton moved 98.9%, the labrale superior moved 32.0%, the stomion moved 45.2%, and the labrale inferior moved 79.6%. The same measurements were performed in the vertical plane, and changes in soft tissue references were analyzed. There was a marked difference in soft tissue changes after mandibular retropositioning when compared with results after mandibular advancement reported in the literature. CONCLUSION It was concluded that it is of great importance to consider both the direction and the surgical method when predicting profile changes in the vertical as well as sagittal plane after orthognathic surgery.

Periodontal disease associated with interdental osteotomies after orthognathic surgery

PURPOSE One of the main reasons for orthodontics and orthognathic surgery is the prevention of dental loss caused by periodontal disease. Until now there have been no published data describing the periodontal situation near interdental osteotomies after orthognatic surgery. The purpose of this study was to evaluate this situation. PATIENTS AND METHODS Thirty patients with Class II malocclusions were studied 4 to 10 years after segmental orthognathic surgery, analyzing the periodontal condition near osteotomies with the aid of periapical and panoramic radiographs. RESULTS Fifty-one pathologic periodontal lesions were found in the 74 segmental osteotomy sites. There were 35 segmental areas with osseous periodontal defects and 16 segmental areas with missing teeth. CONCLUSION A high incidence of dental and periodontal trauma occurs in the region of segmental osteotomies after orthognathic surgery.

Dentoalveolar changes after surgically assisted maxillary expansion: a three-dimensional evaluation.

OBJECTIVES Surgically assisted rapid palatal expansion (SARPE) is a common procedure to correct maxillary transverse deficiency of >5 mm in patients with closed midpalatal suture. The aim of this study was to three-dimensionally analyze skeletal and dentoalveolar changes after SARPE. STUDY DESIGN Eighteen mature patients (mean age 26 years) with a palatal transverse deficiency underwent SARPE. The surgical procedure consisted of a lateral osteotomy combined with an interradicular osteotomy between the roots of the upper central incisors. Measuring points were defined on teeth as well as facial skeleton. Computerized tomography scans were performed preoperatively and immediately after the expansion period. RESULTS Changes of the dentoalveolar and maxillofacial complex were analyzed. CONCLUSIONS Bilateral osteotomy combined with a sagittal osteotomy between the roots of the upper central incisors is a safe method of surgically assisted maxillary expansion. The amount of dentoalveolar tipping was smaller than reported in literature. The expansion was mostly achieved by maxillary expansion.

Stability of dental implants in microvascular osseous transplants

&NA; Microvascular iliac crest and scapula transplants have been used in reconstruction of the lower jaw following tumor surgery. It has only been with the insertion of dental implants that a satisfactory prosthetic rehabilitation of the patient has been achieved. For this study, a follow‐up of 38 patients with lower jaw tumors was carried out. The patients had been treated with partial resection of the lower jaw and neck dissection with microvascular iliac crest transplants (n = 20) or microvascular scapula transplants (n = 18); this was followed with dental implants (n = 143) in the region of the transplants or the local lower jaw. One hundred thirty‐nine of the 143 dental implants were loaded by prosthetic superstructures. In all patients, the implant situation was evaluated on average 2 years 5 months after implantation. Periotest values, periimplant probing depths, and contact bleeding were registered, and the extent of periimplant bone loss was defined radiographically. The clinical situation in the region of the implant was compared for both types of implants and also with the nonresected lower jaw. The average Periotest values were within the normal range for all groups. In one scapula implant, however, a better average of Periotesting, ‐ 3.3, was found compared with implants of the iliac crest with Periotest values of ‐0.7. A measurement of ‐2.1 was found for the local lower jaw, similar to that of scapula implants. Pathologic probing depths were found for all three compared groups. The radiographically determined vertical loss of bone was the same for all three groups, on average 1 mm at 27 months postoperatively. The highest incidence of sulcus bleeding was found in the scapula implant group. Thus, it can be stated that the scapula transplants provide a similar transplant site to local lowerjaw bone, whereas implants in iliac crest transplants show lesser bony stability. Periimplant soft‐tissue conditions are worse for both types of transplants compared with local tissue of the lowerjaw. (Plast. Reconstr. Surg. 109: 916, 2002.)

MR imaging of the TMJ. MR diagnosis and intraoperative findings

Magnetic resonance imaging provides the possibility of a non-invasive method for the investigation of the soft tissues of the temporomandibular joint (TMJ). Between March 1991 and August 1992 we performed static and dynamic magnetic resonance images (MRI) on 47 TMJs of 37 symptomatic patients using a MR-tomograph with a 6.5 cm surface coil. MR diagnosis could be verified in 15 joints at operation and in 3 cases by arthrotomography. Disc position was confirmed in 80%, perforations were missed in 2 out of 3 cases and two more perforations became obvious during operation. One patient refused MR examination, in 2 cases MRI had to be abandoned because of the patients claustrophobia. In our work we wanted to show that MRI is a reliable tool to determine disc position, disc shape and disc behaviour during motion. Detection of perforations is still the domain of arthrography.

Cephalometric and occlusal outcome in adults with unilateral cleft lip, palate, and alveolus after two different surgical techniques

OBJECTIVE To assess differences in the aesthetic and functional long-term results of one-stage and two-stage surgical and orthodontic treatment in patients with cleft lip, palate, and alveolus. DESIGN Sixty adult patients who were operated on as children for unilateral cleft lip, palate, and alveolus were examined. In every patient the lip was closed using Tennisons technique. Thirty patients had soft and hard palate closure in two stages and 30 patients in a single stage. Lateral cephalometric and model analyses were conducted at a mean age of 18.4 years. RESULTS In the model analysis, transverse narrowing was seen in all patients after two-stage operations and in three patients after one-stage operations. The deficit was more severe in the molar region in the two-stage group and nearly similar in the premolar and molar region in the one-stage group. A sagittal deficiency in the anterior maxilla was found in 26 patients after two-stage operations and in 16 patients after one-stage operations. In the lateral cephalometric analysis, the mean sella-nasion-point A angle in the one- and two-stage group was 78.2 degrees and 76.8 degrees, respectively. The ANB angle was normal in both groups. In both groups the inclination of the midface was low. There was a low posterior facial height. Minor scarring was seen in the single-stage group. CONCLUSION A more severe impairment of growth of the maxilla in the sagittal and frontal plane was observed after two-stage operations on the cleft palate.

Aesthetic and Functional Outcome of Surgical and Orthodontic Correction of Bilateral Clefts of Lip, Palate, and Alveolus

OBJECTIVE To assess the aesthetic and functional long-term results of surgical and orthodontic treatment of patients with bilateral cleft lip, palate, and alveolus. DESIGN Long-term follow-up study. SETTING Teaching hospital in Austria. PATIENTS Twenty adult patients who had been operated on as children for bilateral cleft lip, palate, and alveolus. INTERVENTIONS Lateral cephalometric and model analysis. The sum of all mesiodistal tooth diameters in the maxilla and mandible were compared with standard Bolton tracings. MAIN OUTCOME MEASURES Aesthetic and functional results. RESULTS (MODEL ANALYSIS): The upper arch was too wide in 12 patients and the mandibular arch was too wide in 4 patients. In 11 patients, the lateral teeth were crowded, and all had a persistent transverse space deficit and a reduction in sagittal measurements. Fifteen patients had alveolar midline displacement of the maxilla as well as of the mandible. RESULTS (LATERAL CEPHALOMETRIC MEASUREMENTS): The lateral cephalograms showed a mean sella-nasion-A point angle of 77 degrees and a maxillary baseline-nasion-sella line angle of 9 degrees, indicating a tendency toward maxillary retrognathia. An anterior facial height index of 42% (compared with the standard 58%) indicated a slight reduction in midface height with consequent increase in the height of the lower face. CONCLUSION There is specific growth impairment of the midface in adults who were treated as children for bilateral clefts of lip, palate, and alveolus. An optimal result can be achieved only by additional orthognathic surgery (Le Fort II osteotomy).