Philipp Metzler

Three-Dimensional Virtual Surgery Accuracy for Free Fibula Mandibular Reconstruction: Planned Versus Actual Results

PURPOSE Virtual surgical planning (VSP) can promote efficiency, but the ability to transfer the proposed plan to the actual result has not been adequately studied. The purpose of this study was to morphometrically compare the virtually preplanned scenario with the postoperative 3-dimensional (3D) anatomic result. MATERIALS AND METHODS A retrospective review of 10 patients who underwent mandibular reconstruction using a free fibula flap and VSP were evaluated. Pre- and postoperative Digital Imaging and Communications in Medicine files were imported into Mimics 10.01 software (Materialise, Leuven, Belgium) for surgical planning. Preoperative VSP and 1-week postoperative computed tomographic (CT) scans were evaluated to assess surgical accuracy using VSP. The pre- and postoperative morphometric measurements were compared using the Student t test. RESULTS Twenty CT scans from 10 patients (mean age, 56.9±20.2 yr) who underwent partial mandibular resection were analyzed. The dimensions of the fibula segments after osteotomy showed no difference from the preoperative VSP (mean difference in fibula height, 1.2 mm; mean difference in width, 0.9 mm; mean difference in length, 1.3 mm). The postoperative anterior and posterior mandibular angles differed from the VSP by 12.4° and -12.5°, respectively. The condylar distance and inclination showed a discrepancy of only 1.7 mm and 4.6°, respectively, between VSP and postoperative CT scans. CONCLUSIONS VSP confers reproducible precision and accuracy for free fibular mandibular reconstruction. The benefit was most striking for large reconstructions requiring multiple fibular segments. Future directions include assessing the use of external registration devices to enhance surgical accuracy and to follow patients longitudinally to monitor the long-term benefit of VSP.

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.

Bisphosphonate-Induced Osteonecrosis of the Jaw: Comparison of Disease Extent on Contrast-Enhanced MR Imaging, [18F] Fluoride PET/CT, and Conebeam CT imaging

BACKGROUND AND PURPOSE: Imaging of bisphosphonate-induced osteonecrosis of the jaw is essential for surgical planning. We compared the extent of BONJ on contrast-enhanced MR imaging, [18F] fluoride PET/CT, and panoramic views derived from standard conebeam CT with clinical pre- and intraoperative examinations. MATERIALS AND METHODS: Between February 2011 and January 2012, ten subjects with written informed consent (9 women; mean, 69.6 years; range, 53–88 years) were included in this prospective ethics-board-approved study. Patients underwent CEMR imaging, [18F] fluoride PET/CT, and CBCT and were clinically examined pre- and intraoperatively. Surgery was performed, and BONJ was histologically confirmed in 9 patients. Location and extent of BONJ on different modalities/examinations were graphically compared (0 = no pathologic finding, 1 = smallest, 5 = largest extent of BONJ). Rank tests were used to assess overall and paired differences of ratings in 9 patients. A P value <.05 was considered statistically significant. RESULTS: Significant differences in BONJ extent among different modalities and examinations were found (P < .001). The highest median rank was seen in PET/CT (4 ± 1.12) and CEMR imaging (4 ± 1.01), followed by intraoperative examinations (3 ± 0.71), CBCT (2 ± 0.33), and preoperative examinations (1 ± 0). No significant differences were found between PET/CT and CEMR imaging (P = .23), except when comparing PET/CT to either CBCT, pre- and intraoperative examinations (all P < .05). Preoperative examinations showed significantly less extensive disease than all other modalities/examinations (all P < .05). CONCLUSIONS: [18F] fluoride PET/CT and CEMR imaging revealed more extensive involvement of BONJ compared with panoramic views from CBCT and clinical examinations.

Diabetes mellitus negatively affects peri-implant bone formation in the diabetic domestic pig

AIM Diabetes mellitus is classified as a relative contraindication for implant treatment, and higher failure rates have been seen in diabetic patients. The aim of the present study was to investigate the effect of diabetes on peri-implant bone formation in an animal model of human bone repair. MATERIALS AND METHODS Diabetes was induced by an intra-venous application of streptozotocin (90 mg/kg) in 15 domestic pigs. Implants were placed after significant histopathological changes in the hard and soft tissues were verified. The bone-implant contact (BIC), peri-implant bone mineral density (BMD), and expression of collagen type-I and osteocalcin proteins were qualitatively evaluated 4 and 12 weeks after implantation. Fifteen animals served as healthy controls. RESULTS Diabetes caused pathological changes in the soft and hard tissues. The BIC and BMD were significantly reduced in the diabetic group after 4 and 12 weeks. Collagen type-I was increased in the diabetic group at both time points, whereas osteocalcin was reduced in the diabetic group. CONCLUSIONS Poorly controlled diabetes negatively affects peri-implant bone formation and bone mineralization. These findings have to be taken into consideration for diabetic patients with an indication for implant therapy.

The effect of current used bone substitution materials and platelet-rich plasma on periosteal cells by ectopic site implantation: An in-vivo pilot study

The aim of this study was to investigate de novo bone formation following ectopic site implantation of bone substitutes covered by periosteum, with and without the application of autologous platelet-rich plasma (PRP). Twenty-four weeks after subcutaneous implantation of various bone substitutes (bovine hydroxyapatite (bHAP), phycogenic hydroxyapatite (pHAP), and bioglass (BG)) in 35 mini-pigs, bone regeneration rates were compared microradiographically and histologically. Without PRP, bHAP showed a mean de novo bone formation of 32.41%±29.99, in contrast to the other substitute materials where no mineralization could be detected. In combination with PRP, in the bHAP (63.61%±12.98; p±0.03) and pHAP (34.37±29.38; p=0.015) group, significantly higher de novo bone formation was ascertained than without PRP. No ossification could be detected in the BG group. In conclusion, bHAP and pHAP bone substitutes in combination with PRP showed a significant positive effect on periosteal cells by de novo bone formation after ectopic, subcutaneous, low-vascular site implantation.

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.

Assessment of three-dimensional nasolabial response to Le Fort I advancement

BACKGROUND Le Fort I advancement induces soft tissue changes to the nasolabial region. The correlation of sagittal skeletal movement to soft tissue alteration has been studied using 2D methods. However, the influence of maxillary advancement has not been adequately assessed using three-dimensional means. The purpose of this study is to analyze nasolabial changes following Le Fort I advancement using 3D photometric measurements. METHODS Patient demographic information and their amount of advancement were tabulated. Pre- and postoperative 3D photographs (3D VECTRA photosystem, Canfield, Fairfield, NJ) were recorded. Nasolabial anthropometric measurements were performed using the corresponding 3D post-processing software (Mirror). Six month minimum follow-up elapsed before final evaluation. RESULTS Forty-four 3D photo data sets were included. Mean maxillary advancement was 5.5 (±1.9) mm. Male/female ratio was 0.7 with a mean age of 16.7 years. Significant increases (p < 0.0001) were seen in the alar base, alar widths, nostril width, and in the soft triangle and lateral alar angles. Significant decreases (p < 0.0001) were noted in the nasofrontal angle and in nostril height. A significant (p < 0.05) increase of the nasal tip, columella and upper lip projection was seen. Philtral height showed no significant changes (p > 0.05) after maxillary advancement. No significant correlation (p > 0.05) between the degree of soft tissue changes and the amount of maxillary advancement was found. CONCLUSION Le Fort I advancement significantly impacts the nasolabial soft tissue envelope. The 3D soft tissue changes are predictable and similar for any advancement up to 10 mm.

The Reliability of a Three-Dimensional Photo System- (3dMDface-) Based Evaluation of the Face in Cleft Lip Infants

Ample data exists about the high precision of three-dimensional (3D) scanning devices and their data acquisition of the facial surface. However, a question remains regarding which facial landmarks are reliable if identified in 3D images taken under clinical circumstances. Sources of error to be addressed could be technical, user dependent, or patient respectively anatomy related. Based on clinical 3D photos taken with the 3dMDface system, the intra observer repeatability of 27 facial landmarks in six cleft lip (CL) infants and one non-CL infant was evaluated based on a total of over 1,100 measurements. Data acquisition was sometimes challenging but successful in all patients. The mean error was 0.86 mm, with a range of 0.39 mm (Exocanthion) to 2.21 mm (soft gonion). Typically, landmarks provided a small mean error but still showed quite a high variance in measurements, for example, exocanthion from 0.04 mm to 0.93 mm. Vice versa, relatively imprecise landmarks still provide accurate data regarding specific spatial planes. One must be aware of the fact that the degree of precision is dependent on landmarks and spatial planes in question. In clinical investigations, the degree of reliability for landmarks evaluated should be taken into account. Additional reliability can be achieved via multiple measuring.

Craniofacial landmarks in young children: how reliable are measurements based on 3-dimensional imaging?

Introduction Different approaches for 3-dimensional (3D) data acquisition of the facial surface are common nowadays. Meticulous evaluation has proven their level of precision and accuracy. However, the question remains as to which level of craniofacial landmarks, especially in young children, are reliable if identified in 3D images. Potential sources of error, aside from the systems technology itself, need to be identified and addressed. Reliable and unreliable landmarks have to be identified. Materials and Methods The 3dMDface System was used in a clinical setting to evaluate the intraobserver repeatability of 27 craniofacial landmarks in 7 young children between 6 and 18 months of age with a total of 1134 measurements. Results The handling of the system was mostly unproblematic. The mean 3D repeatability error was 0.82 mm, with a range of 0.26 mm to 2.40 mm, depending on the landmark. Single landmarks that have been shown to be relatively imprecise in 3D analysis could still provide highly accurate data if only 1 of the 3 spatial planes was relevant. There were no statistical differences from 1 patient to another. Conclusions Reliability in craniofacial measurements can be achieved by such 3D soft-tissue imaging techniques as the 3dMDface System, but one must always be aware that the degree of precision is strictly dependent on the landmark and axis in question. For further clinical investigations, the degree of reliability for each landmark evaluated must be addressed and taken into account.

Stafne bone cavities: systematic algorithm for diagnosis derived from retrospective data over a 5-year period

Stafne bone cavities are usually found in men 50-70 years old. Typically they appear as lingual, open, ovoid lesions of the molar region of the lower jaw, and most contain parts of the submandibular gland. We have retrospectively examined panoramic radiographs acquired over a 5-year period. All lesions suspected of being Stafne bone cavities were included and analysed further to retrieve statistical information and derive a systematic diagnostic algorithm. We identified 21 Stafne bone cavities among 2928 patients (0.7%). Four of these were confirmed on cone-beam computed tomography (CT). One patient had magnetic resonance imaging (MRI) to confirm the diagnosis. The M:F ratio was 14:7 and the mean age 53 years (range 22-82). All cavities were located in the posterior mandible, 9 on the right and 12 on the left. The mean length was 10.9 (range 4.5-23) mm and height 5.7 (range 3.3-17.3) mm. All cavities were located in the posterior mandible. Sixteen panoramic radiographs (0.6%) were classified as possibly having a Stafne bone cavity but did not fulfil enough criteria to confirm the diagnosis. These 16 were not further analysed. It is rare to diagnose a Stafne bone cavity on a panoramic radiograph. Thorough investigation is essential to exclude differential diagnoses such as keratocystic odontogenic tumour, ameloblastoma, or a metastasis. In atypical presentations 3-dimensional cone-beam CT is helpful to verify the lingual opening. If the diagnosis is still not clear, it can be confirmed by MRI.