Wolfgang Zemann

Three-dimensional evaluation of secondary alveolar bone grafting using a 3D- navigation system based on computed tomography: a two-year follow-up.

Secondary bone grafting is widely used in the closure of oronasal fistulas and reconstruction of maxillary defects. It often fails from lack of physiological stress or inadequate covering of the transplanted bone with surrounding tissue. The aim of this study was to assess the exact bone volume after secondary alveolar bone grafting over a period of two years using a navigation system based on computed tomography (CT). We examined 20 patients with complete unilateral cleft lip and palate (UCLP) who had been treated by secondary bone grafting during late mixed dentition. CT scans of the upper jaw were taken immediately preoperatively, and 1 and 2 years postoperatively. The cleft defects and the bony bridges were marked on the monitor. The software of the navigation system created three-dimensional models showing the amount and site of bone resorption. The mean bone loss after one and two years was 51% and 52%, respectively. There was a significant correlation between the size of the cleft and the success of the alveolar bone grafting (p=0.01). When the teeth adjacent to the cleft were missing the amount of bone lost was 95% after the first year. There was also significant bone loss in the buccopalatine direction. Three-dimensional reconstruction of the bony bridges with a navigation system accurately shows the amount of bone within the cleft site. This method is definitely superior to conventional two-dimensional orthopantomography.

Osteopathology induced by bisphosphonates and dental implants: clinical observations

ObjectivesAlthough there are many reports about risk factors for the development of BP-associated osteonecrosis of the jaws, the role of dental implants as a local risk factor is still discussed, especially in patients with oral BP treatment. Until now, a few case reports and surveys display a possible minor risk in patients with oral BP therapy, whereas the avoidance of implant placement is generally accepted in patients with intravenous BP therapy.Patient and methodsIn this study, the cases of 14 patients with osteonecrosis of the jaws in association with BP therapy and dental implant placement were analyzed carefully with a detailed literature review.ResultsOf 14 patients, nine had underlying malignant disease and five patients had osteoporosis. In ten patients, implants were placed either in the posterior mandible or maxilla; the mean interval between implant insertion and disease onset was 20.9 months. Pain (n12) and signs of infection (n10) were the most common symptoms. Histologically, signs of infection were found in nine of 11 analyzed patients with presence of Actinomyces in six patients. Two patients turned out to have infiltration of underlying malignant disease.ConclusionsPosteriorly placed implants seem to be of higher risk of development of osteonecrosis of the jaws. Not only the implant placement but also the inserted implant itself seems to be a continuous risk factor.Clinical relevanceThe herein elaborated risk factors help dentists plan dental rehabilitation with implants in this high-risk group of patients and indicate careful and regular dental recall.

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.

Point-to-point registration with mandibulo-maxillary splint in open and closed jaw position. Evaluation of registration accuracy for computer-aided surgery of the mandible

INTRODUCTION Computer navigation plays an increasingly important role in craniomaxillofacial surgery. The difficulties in computer navigation at the craniomaxillofacial site lie in the accurate transmission of the dataset to the operating room. This study investigates the accuracy of the dental-splint registration method for the skull, midface, and mandible. MATERIAL AND METHODS A synthetic human skull model was prepared with landmarks and scanned with cone beam computer tomography (CBCT). Two registration splints fixed the mandible against the viscerocranium in two different positions (closed vs. open). The target registration error was computed in all 278 landmarks spread over the entire skull and mandible in 10 repeated measurements using the VectorVision(2) (BrainLAB Inc., Feldkirchen, Germany) navigation system. RESULTS If registered in the closed position an average precision of 2.07 mm with a standard deviation (SD) of 0.78 mm was computed for all landmarks distributed over the whole skull. Registration in the open position resulted in an average precision of 1.53 mm (SD=0.55 mm). For single landmarks the precision decreases linearly with distance from the reference markers. The longer the three-dimensional distance between the registration points, the more precise the computer navigation is, mainly in the most posterior area of the cranium. CONCLUSION Our findings in the cranium are comparable with those of other studies. Artificial fixation of the lower jaw via splint seems to introduce no additional error. The registration points should be as far apart from each other as possible during navigation with the splint.

SAPHO syndrome with affection of the mandible: diagnosis, treatment, and review of literature

The synovitis, acne, pustulosis, hyperostosis, and osteitis (SAPHO) syndrome is a rare syndrome of unknown etiology. Involvement of the mandible is found in almost 10% of cases. In the literature, conservative treatment is recommended most often, because decortication and partial resection are found to be ineffective and of temporary profit. We report a case of SAPHO syndrome in a 44-year-old women with unilateral hyperostosis of the mandible and massive painful swelling of the surrounding soft tissues. Owing to facial disfiguration and pain, resection of the affected bone followed by immediate reconstruction with a microvascular iliac crest flap were performed. The aim of this paper was to present the necessity of surgical intervention in SAPHO syndrome of the mandible in cases of esthetic and functional limitation.

Osteopathology of the jaw associated with bone resorption inhibitors: what have we learned in the last 8 years?

QUESTIONS UNDER STUDY 8 years after discovery of osteonecrosis of the jaw associated with bisphosphonate therapy a lot of experience has been garnered in treating 112 patients with this disease. This disease, although uncommon, is still a burden for the patient as well as the treating specialists and an adequate standardised classification as well as therapy does not exist. This article presents a summary of collected patient data, garnered experience and consequential changes in knowledge, in diagnostic measures and therapy. METHODS The data of in total 112 patients referred to the Special Clinics for patients with bisphosphonate-associated lesions of the jaw was retrospectively analysed and compared with data from the literature. RESULTS In total, 110 patients, 70% women, were included in the data analysis. A quarter of those patients had osteoporosis as the underlying disease, more than half of all patients had extractions as the local influencing factor. The lesion was localised in the mandible in three quarters of all patients and almost all patients showed clinical signs of infection. In total, 58% of all patients were treated surgically with a complete remission rate of 78% over 7 years. CONCLUSIONS This summary of patient data and literature shows that knowledge about bisphosphonate-associated osteopathology of the jaw becomes more and more specific. The range of drugs associated with this disease has increased, but also therapeutic options show more and more success. Classifications, published shortly after the discovery of BRONJ need to be revised and new knowledge included.

Maxillary segmental distraction in children with unilateral clefts of lip, palate, and alveolus

OBJECTIVES Alveolar clefts are commonly closed by a bone grafting procedure. In cases of wide clefts the deficiency of soft tissue in the cleft area may lead to wound dehiscence and loss of the bony graft. Segmental maxillary bony transfer has been mentioned to be useful in such cases. Standard distraction devices allow unidirectional movement of the transported segment. Ideally the distraction should strictly follow the dental arch. The aim of this study was to analyze distraction devices that were adapted to the individual clinical situation of the patients. The goal was to achieve a distraction strictly parallel to the dental arch. STUDY DESIGN Six children with unilateral clefts of lip, palate, and alveolus between 12 and 13 years of age were included in the study. The width of the cleft was between 7 and 19 mm. Dental cast models were used to manufacture individual distraction devices that should allow a segmental bony transport strictly parallel to the dental arch. Segmental osteotomy was performed under general anesthesia. Distraction was started 5 days after surgery. All distracters were tooth fixed but supported by palatal inserted orthodontic miniscrews. RESULTS In all patients, a closure of the alveolar cleft was achieved. Two patients required additional bone grafting after the distraction procedure. The distraction was strictly parallel to the dental arch in all cases. In 1 case a slight cranial displacement of the transported maxillary segment could be noticed, leading to minor modifications of the following distractors. CONCLUSION Distraction osteogenesis is a proper method to close wide alveolar clefts. Linear segmental transport is required in the posterior part of the dental arch, whereas in the frontal part the bony transport should run strictly parallel to the dental arch. An exact guided segmental transport may reduce the postoperative orthodontic complexity.

Sagittal maxillary growth in children with unilateral cleft of the lip, alveolus and palate at the age of 10 years: An intercentre comparison

OBJECTIVE Aim of this intercentre study was to compare sagittal facial growth in children with unilateral cleft lip and palate treated with different surgical protocols. A first evaluation had been carried out at the age of 6 years, now the patients have been re-evaluated at the age of 10 years. MATERIAL AND METHOD 22 patients had been analyzed in centre 1, 32 patients in centre 2. All patients had presurgical orthopaedics. Centre 1 had lip repair at the age of 3 months and one-stage palatal closure with 1 year. Centre 2 had lip repair with 6 months, soft palate repair at 12 and hard palate repair at the age of 30 months. Sagittal growth was evaluated on lateral cephalograms. As control, data of 35 non-cleft children were used. Statistical analysis was carried out with students t-test, multiple comparisons with Bonferroni. RESULTS There was considerably normal sagittal facial growth in centre 1, with tendency of forward growth of the mandible. In centre 2 there was a slight decrease in sagittal maxillary and mandibular growth with unchanged intergnathic relation. There was no statistically significant difference in sagittal growth between the centres. A re-evaluation has to be carried out after the final growth spurt.

Is mandibular reconstruction using vascularized fibula flaps and dental implants a reasonable treatment

PURPOSE this study retrospectively analyzed the rate of screwed implant insertion and risk factors in patients undergoing mandibular reconstruction with microsurgical revascularized fibula flaps. METHODS This study retrospectively analyzed all patients with microvascularized fibula grafts between 1997 and 2005. Collected data included general data and risk factors (e.g., smoking, alcohol use), and irradiation was the main predictor variable. The number of patients rehabilitated with dental implants and the implant success rate were evaluated, possible influencing factors were identified, and the results were compared with previously published data. RESULTS The sample included 33 patients (17 men, 16 women; mean age: 52 years); 76% were smokers, 42% drank alcohol regularly, and 73% had undergone mandible irradiation. Twenty-three patients received 140 screw-retained implants for dental rehabilitation. Twenty-three implants were lost. Overall 1- and 5-year implant survival rates were 94% and 83%, respectively. Implant survival rates were 86% in non-irradiated mandibular bone, 86% in non-irradiated grafted fibular bone, 82% in irradiated mandibular bone, and 38% in irradiated grafted fibular bone. CONCLUSION This study showed that the use of dental implants in patients with fibula flaps is an appropriate and successful option for dental rehabilitation, even in those with risk factors such as smoking, alcohol use, and irradiation. Implant placement in irradiated grafted bone seems to be a high-risk procedure.

Registration for computer-navigated surgery in edentulous patients: A problem-based decision concept

BACKGROUND Surgical navigation is a commonly used tool in cranio-maxillofacial surgery. Registration is the key element for precision, and a number of studies have shown different techniques to be accurate. Nonetheless, uncertainty surrounds the special situation in edentulous patients and a practical approach to what can be a challenging problem. MATERIALS AND METHODS Four registration strategies for the Brainlab VectorVision(2) system are presented for surgical navigation of edentulous patients: three landmark-based, point-to-point techniques and one surface-based matching strategy are evaluated. RESULTS The methods described differ in overall accuracy as well as in the region covered. In general, the more time-consuming and invasive the technique, the more precise it is. The non-invasive techniques are less precise, and they cover only small regions with sufficient accuracy. CONCLUSIONS Taking into account which type of accuracy is clinically relevant and that the whole skull does not always need to be covered with the greatest possible accuracy, all the described techniques have their indications. The simpler and less invasive techniques can spare time, decrease costs, and harm patient. A decision tree is presented to the reader.