Reconstruction of dental roots for implant planning purposes: a retrospective computational and radiographic assessment of single-implant cases.

PURPOSE: The aim of the study was to assess the deviation between clinical implant axes (CIA) determined by a surgeon during preoperative planning and reconstructed tooth axes (RTA) of missing teeth which were automatically computed by a previously introduced anatomical SSM. METHODS: For this purpose all available planning datasets of single-implant cases of our clinic, which were planned with coDiagnostix Version 9.9 between 2018 and 2021, were collected for retrospective investigation. Informed consent was obtained. First, the intraoral scans of implant patients were annotated and subsequently analyzed using the SSM. The RTA, computed by the SSM, was then projected into the preoperative planning dataset. The amount and direction of spatial deviation between RTA and CIA were then measured. RESULTS: Thirty-five patients were implemented. The mean distance between the occlusal entry point of anterior and posterior implants and the RTA was 0.99 mm ± 0.78 mm and 1.19 mm ± 0.55, respectively. The mean angular deviation between the CIA of anterior and posterior implants and the RTA was 12.4° ± 3.85° and 5.27° ± 2.97° respectively. The deviations in anterior implant cases were systematic and could be corrected by computing a modified RTA (mRTA) with decreased deviations (0.99 mm ± 0.84 and 4.62° ± 1.95°). The safety distances of implants set along the (m)RTA to neighboring teeth were maintained in 30 of 35 cases. CONCLUSION: The RTA estimated by the SSM revealed to be a viable implant axis for most of the posterior implant cases. As there are natural differences between the anatomical tooth axis and a desirable implant axis, modifications were necessary to correct the deviations which occurred in anterior implant cases. However, the presented approach is not applicable for clinical use and always requires manual optimization by the planning surgeon.

Feasibility of Implant Strain Measurement for Assessing Mandible Bone Regeneration.

Nonunion is one of the most dreaded complications after operative treatment of mandible fractures or after mandible reconstruction using vascularized and non-vascularized bone grafts. Often diagnosis is made at advanced stage of disease when pain or complications occur. Devices that monitor fracture healing and bone regeneration continuously are therefore urgently needed in the craniomaxillofacial area. One promising approach is the strain measurement of plates. An advanced prototype of an implantable strain measurement device was tested after fixation to a locking mandible reconstruction plate in multiple compression experiments to investigate the potential functionality of strain measurement in the mandibular region. Compression experiments show that strain measurement devices work well under experimental conditions in the mandibular angle and detect plate deformation in a reliable way. For monitoring in the mandibular body, the device used in its current configuration was not suitable. Implant strain measurement of reconstruction plates is a promising methodical approach for permanent monitoring of bone regeneration and fracture healing in the mandible. The method helps to avoid or detect complications at an early point in time after operative treatment.

Analysis of the accuracy of computer-assisted DCIA flap mandibular reconstruction applying a novel approach based on geometric morphometrics.

BACKGROUND: This study evaluated the accuracy of computer-assisted surgery (CAS)-driven DCIA (deep circumflex iliac artery) flap mandibular reconstruction by traditional morphometric methods and geometric morphometric methods (GMM). METHODS: Reconstruction accuracy was evaluated by measuring distances and angles between bilateral anatomical landmarks. Additionally, the average length of displacements vectors between landmarks was computed to evaluate factors assumed to influence reconstruction accuracy. Principal component analysis (PCA) was applied to unveil main modes of dislocation. RESULTS: High reconstruction accuracy could be demonstrated for a sample consisting of 26 patients. The effect of the number of segments and length of defect on reconstruction accuracy were close to the commonly used significance threshold (p = 0.062/0.060). PCA demonstrated displacement to result mainly from sagittal and transversal shifts. CONCLUSIONS: CAS is a viable approach to achieve high accuracy in mandibular reconstruction and GMM can facilitate the evaluation of factors influencing reconstruction accuracy and unveil main modes of dislocation in this context.

Cranial reconstruction evaluation - comparison of European statistical shape model performance on Chinese dataset.

Purpose: Morphological variability of the skull is an important consideration for cranioplasty and implant design. Differences in morphology of the skull based on the ethnicity are known. In a previous study we could show the accuracy and benefits of virtual reconstructions based on a statistical shape model (SSM) for neurocranial defects. As the SSM is trained on European data, the question arises how well this model fares when dealing with patients with a different ethnic background. In this study we aim to evaluate the accuracy and applicability of our proposed method when deploying a cranial SSM generated from European data to estimate missing parts of the neurocranium in a Chinese population. Methods: We used the same data and methods as in our previous study and compared the outcomes when applied to Chinese individuals. A large unilateral defect on the right side and a bilateral defect were created. The outer surface of the cranial table was reconstructed from CT scans, meshed with triangular elements, and registered to a template. Principal component analysis together with Thin Plate Spines (TPS) deformation was applied to quantify modes of variation. The mesh to mesh distances between the original defects´ surfaces and the reconstructed surface were computed. Results: Comparing the Chinese test group with the European control group, regarding the entire defect the analysis shows no significant difference for unilateral defects (test vs. control group/0.46 mm ± vs. 0.44 mm). Reconstruction of bilateral defects exhibited only in slightly higher prediction errors than those of unilateral defects (0.49 mm ± vs. 0.45 mm). Conclusion: The proposed method shows a high accuracy that seems to be ethnical independent - with low error margins for virtual skull reconstruction and implant design.Clinical relevance: Metallic objects may severely impact image quality in several CBCT devices.

Analyzing the Fitting of Novel Preformed Osteosynthesis Plates for the Reduction and Fixation of Mandibular Fractures.

PURPOSE: The known preformed osteosynthesis plates for the midface are helpful tools for a precise and fast fixation of repositioned fractures. The purpose of the current study is to analyze the precision of newly developed prototypes of preformed osteosynthesis plates for the mandible. METHODS: Four newly designed preformed osteosynthesis plates, generated by a statistical shape model based on 115 CT scans, were virtually analyzed. The used plates were designed for symphyseal, parasymphyseal, angle, and condyle fractures. Each type of plate has three different sizes. For analysis, the shortest distance between the plate and the bone surface was measured, and the sum of the plate-to-bone distances over the whole surface was calculated. RESULTS: A distance between plate and bone of less than 1.5 mm was defined as sufficient fitting. The plate for symphyseal fractures showed good fitting in 90% of the cases for size M, and in 84% for size L. For parasymphyseal fractures, size S fits in 80%, size M in 68%, and size L in 65% of the cases. Angle fractures with their specific plate show good fitting for size S in 53%, size M in 60%, and size L in 47%. The preformed plate for the condyle part fits for size S in 75%, for size M in 85%, and for size L in 74% of the cases. CONCLUSION: The newly developed mandible plates show sufficient clinical fitting to ensure adequate fracture reduction and fixation.

The statistical shape model as a quality assurance measure in the treatment of complex midface fractures: a case control study.

BACKGROUND: Complex bilateral midface fractures necessitate a surgically challenging procedure to preserve or restore the occlusion and the sensitive eye area. In this case control study, we aim to show the potential of a statistical shape model (SSM) for measuring the quality of the midface reconstruction, compared to the estimated preoperative situation. METHODS: An individualized SSM was postoperatively registered on 19 reconstructed complex bilateral midface fractures. Using this SSM, the distances from the simulated preoperative situation to the postoperative positions of the fracture segments were calculated. The fracture lines for Le Fort II, Le Fort III, and NOE fractures were chosen as reference points for the distance measurements. RESULTS: The SSM could be registered on all 19 complex bilateral midface fractures. All analyzed fractures showed a dorsal impaction (negative values) of the midface. Le Fort II fractures showed deviation values of -0.98 ± 4.6 mm, Le Fort III fractures showed values of -3.68 ± 3.6 mm, NOE type 2 fractures showed values of -0.25 ± 4.6 mm, and NOE type 1 fractures showed values of -0.25 ± 4.6 mm. CONCLUSIONS: The SSM can be used to measure the quality of the achieved reduction of complex bilateral midface fractures based on the estimated preoperative situation. TRIAL REGISTRATION: DRKS00009719.

Do Red Blood Cell Transfusions Influence Long-Term Outcomes in Patients Undergoing Primary Surgery for Oral Squamous Cell Carcinoma?

PURPOSE: There is no consensus on the impact of red blood cell (RBC) transfusion on patients with oral squamous cell carcinoma (OSCC). The purpose of this study was to investigate the association between RBC transfusions and overall survival (OS) and tumor-free survival (TFS) after operative treatment of OSCC. METHODS: In this retrospective cohort study, all patients treated with primary surgery between 2003 and 2017 because of OSCC were chart reviewed. The occurrence and amount of RBC transfusions (0; 1-3; >3 units) was correlated with OS and TFS by Kaplan-Meier survival and Cox regression analyses. Demographic, clinical, and pathological parameters were also evaluated in order to identify confounding factors. RESULTS: Of 420 patients (243 [57.9%] male) with a mean age of 62.6 years, 67 (16.0%) received RBC transfusion. There were statistically significant (P < .01) differences in 5-year OS respectively TFS in transfused patients for the Kaplan-Meier survival analysis (0 units = 70.6%; [95% confidence interval {CI}: 65.0-75.4%] respectively 63.2% [95% CI: 57.4-68.4%], 1-3 units = 47.2% [95% CI: 29.4-63.1%] respectively 40.6% [95% CI: 24.6-55.95%] and >3 units = 48.9% [95% CI: 20.9-72.1%] respectively 30.5% [95% CI: 8.9-55.8%]). After multivariate adjustments for demographic, clinical, and pathological parameters, RBC transfusion could not be sustained as a significant prognostic factor in OS respectively TFS (1-3 units: hazard ratio = 1.5 [95% CI: 0.7-3.2] respectively 1.3 [95% CI: 0.7-2.6]; >3 units: hazard ratio = 1.2 [95% CI: 0.5 - 3.0] respectively 1.1 [95% CI: 0.5-2.4]). CONCLUSIONS: Although RBC transfusion was not identified as a significant prognostic parameter in multivariate analysis, a clear trend for shorter OS and TFS for transfused patients in univariate and Kaplan-Meier survival analysis could be shown.

Dental implants in immunocompromised patients: a systematic review and meta-analysis.

OBJECTIVE: Impaired health conditions and related lack of adequate host healing are among the most important conditions that account for dental implant failure. Today clinicians face an increasing number of immunocompromised patients requesting implant-based rehabilitation. To provide clinical evidence for prospective decision-making, the aim of this systematic review and meta-analysis was to analyse the influence of immunodeficiency on dental implant survival. METHODS: The study was conducted according to the PRISMA Statement and the principles of the Cochrane Collaboration. MEDLINE and Web of Science were searched. Results were calculated by the pooled incidence of implant loss. Reported odds ratios (OR) from fully adjusted models were preferred. Distinct risk estimates were synthesised with 95% confidence intervals. RESULTS: A total of 62 publications including 1751 endosseous implants placed in immunocompromised patients were included. For the follow-up of 24 months and longer, the mean survival rate of implants in patients with HIV was 93.1%, chemotherapy was 98.8%, autoimmune disease was 88.75%, after organ transplantation was 100%. Crohn's disease showed a significant effect on early implant failure and resulted in increased, however not significant, implant loss. CONCLUSION: No significant effect of immunocompromised conditions on implant survival was detectable. Implant-based therapy in immunocompromised patients should not aggravate the general morbidity and must not interfere in life-saving therapies. A careful risk stratification prior implant therapy is fundamental. To further decipher the role of immunosuppression on dental implantology, more data from controlled and randomised studies are needed.

Vascularized scapula and latissimus dorsi flap for CAD/CAM assisted reconstruction of mandibular defects including the mandibular condyle: technical report and clinical results.

BACKGROUND: Reconstruction of mandibular continuity and function after tumor resection is challenging, particularly in cases including the mandibular condyle. Various approaches for reconstruction after disarticulation resection have been reported. However, the scapula flap has received little attention as a treatment option in these cases. PATIENTS AND METHODS: Three cases of computer aided design and computer aided manufacturing (CAD/CAM) assisted reconstruction after disarticulation resection using a vascularized scapula and latissimus dorsi flap are reported. All cases required reconstruction of the mandibular ramus and condyle in combination with the reconstruction of large and complex soft tissue defects. RESULTS: The surgical procedure was deemed successful in all cases. The scapula flap could be placed as preoperatively planned and patients regained their preoperative occlusion pattern and satisfying mouth opening-ranges. The large soft tissue defects could reliably be reconstructed using a latissimus dorsi flap. CONCLUSIONS: The scapula and latissimus dorsi flap can be considered a suitable option for the reconstruction of mandibular disarticulation resection defects in combination with large soft tissue defects.

Analysis of the accuracy of a novel preformed osteosynthesis plate for the reduction and fixation of zygomaticomaxillary complex fractures.

INTRODUCTION: There has been a shift toward surgical treatment of ZMC (zygomaticomaxillary complex) fractures with open reduction and subsequent fixation in the past decades. Anatomically preformed osteosynthesis plates, already used in the field of craniomaxillofacial surgery for the treatment of fractures of the mandible and the orbit, might be a suitable option for ZMC fractures as well. MATERIAL AND METHODS: A statistical shape model was created from 179 cranial CT scans. Based on this surface model, an anatomically preformed plate for the reduction and fixation of ZMC fractures was developed in 3 sizes (S, M, L). Virtual analysis of the accuracy of the plate was performed on a dataset consisting of 120 CT scans. RESULTS: Within a determined tolerance range of 0-1.5 mm, analysis revealed a high accuracy of the plate in 70-87 % of the CT scans. The S-sized plate has the highest overall accuracy, whereas the L-sized plate has highest accuracy at the "base" region which is essential for the placement of the plate. DISCUSSION: The newly developed plate can be placed via an intraoral approach and analysis of the plate has confirmed its accuracy to be sufficient to ensure an adequate fracture reduction and fixation. It thus might allow for a less extensive approach and less approaches/incisions necessary overall to reduce and fixate ZMC fractures.

Virtual reconstruction of bilateral midfacial defects by using statistical shape modeling.

PURPOSE: Mirroring and manual adaptation as the main virtual reconstruction method of midfacial defects is time demanding and ignores asymmetrical skull shapes. By using a statistical shape model (SSM), the reconstruction can be automatized and specified. The current study aims to show the ability of the SSM in the virtual reconstruction of artificial bilateral defects. METHODS: Based on 131 pathologically unaffected CT scans of the adult midface region, an SSM was created. DICOM data were generated, segmented and registered on one mesh, which serves as template for the SSM. The SSM consists of the registered surface meshes and includes the shape variability of the cranial vault. Fractured or missing parts were calculated by the known shape variability of healthy midface data. Using 25 CT scans not included in the SSM, the precision of the reconstruction of virtually placed bilateral defects of the orbital floor (Group 1) and bilateral naso-orbital-ethmoid (NOE) fractures (Group 2). Distances to the corresponding parts of the intact skull were calculated to show the accuracy of the virtual reconstruction method. RESULTS: All defects could be reconstructed by using the SSM and GM technique. The analysis shows a high accuracy of the SSM-driven reconstruction, with a mean error of 0.75 ± 0.18 mm in group 1 and with a mean error of 0.81 ± 0.23 mm in group 2. CONCLUSION: The precision of the SSM-driven reconstruction is high and its application is easy for the clinician because of the automatization of the virtual reconstruction process in the field of computer-assisted surgery (CAS). Respecting of the natural asymmetry of the skull and the methods of GM are reasons for the high precision and the automatization of the new shown reconstruction workflow.

Catching condyle - Endoscopic-assisted transoral open reduction and rigid fixation of condylar process fractures using an auto reposition and fixation osteosynthesis plate.

INTRODUCTION: Fractures of the mandibular condyle are reported to account for 9 %-45 % of all mandibular fractures. There has been a long lasting controversy on the superiority of different treatment options with endoscopic-assisted transoral approaches gaining increasing attention in recent years. In this article, we report the application of a newly developed osteosynthesis plate for an auto reposition, reconstruction and rigid fixation of condylar process fractures. MATERIAL AND METHODS: We present 6 cases of uni- or bilateral fractures of the condylar process treated with a transoral open reduction and rigid fixation using an auto reposition plate. Via a transoral endoscopic assisted approach the proximal condyle fragment is captured using an anatomical defined clinch of the cranial part of the plate. The reposition of the condyle is facilitated with the distal bridge of the plate ranging around the posterior part of the ascending ramus. RESULTS: The results show a sufficient reposition, rigid fixation and no facial nerve palsy or postoperative long-term occlusal disturbances. The mean operating time was 86 min. CONCLUSION: Transoral endoscopic-assisted surgery with application of an auto reposition, reconstruction and fixation plate offers a quick and convenient way for open reconstruction and rigid fixation of condylar process fractures.

Necrotizing fasciitis as a complication of osteonecrosis of the jaw related to oral bisphosphonate application in a patient with osteoporosis: a case report.

BACKGROUND: Necrotizing fasciitis has been reported as a complication secondary to bisphosphonate-related osteonecrosis of the jaw (BRONJ) in a low number of patients. The only report of such a case in an osteoporosis patient found in current literature was related to short-term bisphosphonate but long time corticosteroid and methotrexate treatment. CASE PRESENTATION: In this article, we report a case of necrotizing fasciitis secondary to osteonecrosis of the jaw related to long-term oral bisphosphonate treatment in an osteoporosis patient additionally suffering from poorly controlled type 2 diabetes. Diabetes mellitus not only has been reported to be a systemic risk factor regarding BRONJ but also to be the most common comorbidity in patients presenting with necrotizing fasciitis and to increase mortality of this condition. Necrotizing fasciitis and BRONJ in the patient could eventually be resolved by a surgical approach and intravenous antibiotic therapy. CONCLUSIONS: The case presented suggests diabetes mellitus potentially having been an important factor in the particularly unfavorable course of therapy. It emphasizes the importance of an adequate therapy and surveillance of modifiable systemic risk factors like diabetes mellitus in patients being at risk for development of BRONJ. If necrotizing fasciitis is suspected, early diagnosis and aggressive surgical and medical management are essential to minimize morbidity and mortality.

Numb Chin as Signal for Malignancy-Primary Intraosseous Diffuse Large B-Cell Lymphoma of the Mandible.

Malignant lymphomas are about 5% of all malignant tumors. Extranodal non-Hodgkin's lymphomas (NHLs) are found in 26% of these cases. Lymphomas of the head-and-neck area occur in 2%-3% of all malignancies, with 28% with an extranodal manifestation. Extranodal NHLs in the oral cavity are usually found in the maxilla, and rarely in the mandible. Their symptoms and clinical manifestation have no pathognomonic features; therefore, the expression of this uncommon entity can be diagnosed with an odontogenic inflammatory process, leading to a misdiagnosis. Delay in the decision for a biopsy, and adequate treatment for the patient directly impairs the prognosis of this neoplasm. This study reports a case of a patient with discomfort in the right mandible and paresthesia of the right lower lip and chin without any dental focus. After performing further diagnostic examinations including a subsequent biopsy, the final diagnosis was a diffuse large B-cell lymphoma (DLBCL). Intraosseous DLBCLs are uncommon in the daily clinical routine, but emphasize the need for careful examination by the clinicians also considering the differential diagnosis of sensory neuropathy. Neurological symptoms with no apparent cause should raise the suspicion of malignancy until the opposite is proven.

Planning of skull reconstruction based on a statistical shape model combined with geometric morphometrics.

PURPOSE: Virtual reconstruction of large cranial defects is still a challenging task. The current reconstruction procedures depend on the surgeon's experience and skills in planning the reconstruction based on mirroring and manual adaptation. The aim of this study is to propose and evaluate a computer-based approach employing a statistical shape model (SSM) of the cranial vault. METHODS: An SSM was created based on 131 CT scans of pathologically unaffected adult crania. After segmentation, the resulting surface mesh of one patient was established as template and subsequently registered to the entire sample. Using the registered surface meshes, an SSM was generated capturing the shape variability of the cranial vault. The knowledge about this shape variation in healthy patients was used to estimate the missing parts. The accuracy of the reconstruction was evaluated by using 31 CT scans not included in the SSM. Both unilateral and bilateral bony defects were created on each skull. The reconstruction was performed using the current gold standard of mirroring the intact to the affected side, and the result was compared to the outcome of our proposed SSM-driven method. The accuracy of the reconstruction was determined by calculating the distances to the corresponding parts on the intact skull. RESULTS: While unilateral defects could be reconstructed with both methods, the reconstruction of bilateral defects was, for obvious reasons, only possible employing the SSM-based method. Comparing all groups, the analysis shows a significantly higher precision of the SSM group, with a mean error of 0.47 mm compared to the mirroring group which exhibited a mean error of 1.13 mm. Reconstructions of bilateral defects yielded only slightly higher estimation errors than those of unilateral defects. CONCLUSION: The presented computer-based approach using SSM is a precise and simple tool in the field of computer-assisted surgery. It helps to reconstruct large-size defects of the skull considering the natural asymmetry of the cranium and is not limited to unilateral defects.

Virtual reconstruction of midface defects using statistical shape models.

PURPOSE: This study evaluates the accuracy of a statistical shape model (SSM) for virtual fracture reconstruction of the lateral midface. MATERIALS AND METHODS: A uniform bony defect of the right zygoma was created. A virtual reconstruction was performed by using the standard procedure of mirroring the unaffected to the affected side (Group I) and by using the statistical model based on 178 pathologically unaffected CT scans (Group II). The accuracy of the statistical shape model was evaluated in comparison to the present mirroring protocol. The reconstructed region was compared with the original bone evaluating the mean deviation of both surfaces. RESULTS: All zygomas could be reconstructed with all methods. On the affected side the mean deviation was 1.10 mm ± 0.23 mm in group I and 0.85 mm ± 0.26 mm in group II. The differences between the groups were significant. CONCLUSION: SSM offers a more precise reconstruction of midface defects than mirroring procedures. As an additional element SSM could automatize the CAS workflow in many respects.

Corrigendum to "Effect of Short-Term Stimulation with Interleukin-1ß and Differentiation Medium on Human Mesenchymal Stromal Cell Paracrine Activity in Coculture with Osteoblasts".

[This corrects the article DOI: 10.1155/2015/714230.].

The effect of gabapentin-lactam hydroxamic acid derivatives on ovine osteoblast proliferation and phenotype: perspectives for tissue engineering application.

PURPOSE: Modern bone tissue engineering associated with mesenchymal stem cells (MSCs) provides promising treatment alternatives for the loss of bone, one of the foremost challenges in oral and craniofacial surgery today. The effect of gabapentin-lactam (GBP-L) and its analogs on osteogenic differentiated MSCs has not yet been deciphered. Consequently, this study investigates the effect of novel trans-8-tertbutylgabapentin-lactam (trans-8-TB-GBP-L) hydroxamic acid derivatives on metabolism, proliferation, and physiologic mineralization characteristics of ovine osteoblast cells. MATERIALS AND METHODS: Osteoblasts were extracted and prepared from sheep femoral heads and cultured in medium enriched with hydroxamic acid derivatives of trans-8-TB-GBP-L. The cell proliferation rate, cell metabolism, cell viability, and basic osteoblastic function were assessed. RESULTS: After 3 and 5 days of incubation, no significant increase in DNA content was detected in any of 12 test groups versus the control group. However, after 8 days of incubation, a significant increase of DNA contents in the test groups containing nanomolar concentrations of trans-8-TB-GBP-L hydroxamic acid derivatives was found. No significant aberration in metabolic activity was detected when any of the test substances were applied. ALP displayed similar activity rates among the test groups and the control at all time points. Calcification of osteoblastic cells occurred solely when nanomolar concentrations were used. CONCLUSION: Trans-8-TB-GBP-L hydroxamic acid derivatives do not interfere with physiologic function and phenotype of ovine osteoblasts. However, when applied at nanomolar concentrations, the assessed GBP-L derivatives significantly increased the cell proliferation rate after 8 days of incubation, indicating a dose-response curve with the maximum peak at nanomolar concentration and a retarded drug response between 5 and 8 days.