Comparative radiologic study of bone density and cortical thickness of donor bone used in mandibular reconstruction

Three-dimensional Finite Element Analysis of Implant Prosthesis After Mandibular Reconstruction by Upper Distal Free Double-Barrel Fibula

OBJECTIVE

This study aimed to compare the biomechanics of implant prostheses and peri-implant bone among 6 different mandibular reconstruction models based on patient data involving the use of an upper free-end double-barrel fibula.

METHODS

This study was an observational study. Five models were reconstructed using fibular-supported and implant-supported partial dentures. Two of these models were double-barrel fibula models with different gaps between the upper and lower segments. The other 2 were single-layered fibular models (the fibula was placed at the inferior or superior mandibular borders). The fifth model was a double-barrel fibula with a free distal end on the upper segment. In addition, a typical mandibular model was created for comparison. Two fixed partial-denture models were used in this study. The von Mises stress and strain of the models were analyzed.

RESULTS

The maximum stress decreased with increasing gap between the upper and lower fibula. The distal free-end double-barrel fibula showed a potential to reduce the maximum stress around the implant apex while increasing it around the implant neck compared with a fixed distal-end double-barrel fibula.

CONCLUSIONS

Utilizing a free distal end on the upper fibula may be a viable option for mandibular reconstruction, especially when the fibula length is limited.

LONG-TERM OUTCOMES OF DIFFERENT RECONSTRUCTION OPTIONS USING AUTOGENOUS BONE GRAFT FOR MANDIBULAR RECONSTRUCTION: A RETROSPECTIVE COMPARATIVE STUDY

Background: Several recent studies have attempted to document VBG and NVBG following mandibular reconstruction, mainly the advantages and disadvantages, but very few have specifically evaluated the differences in large parameters including both radiographic and functional aspects for long-term follow-up. However, the object of this study is to compare between two different methods of reconstruction in mandibular defects and to determine the outcomes of different reconstruction options using autogenous vascularized and nonvascularized bone grafts for mandibular reconstruction. Patients and Methods: a total of 39 patients, 22 (56.4%) females and 17 (43.6%) males, with a mean age of 36.41 years at the time of presentation (age ranged for 48 years). Study was performed in two stages at the Department of Head and Neck Surgery - Oral and Maxillofacial oncology. In the First stage (N=39), bone-density, bone resorption, and bone graft failure were examined radiographically on panorex and CBCT. The second stage included functional evaluation (physical examination and questionnaire) based on pain, infection, speech and recurrence. Both groups were followed-up for at least 1month, 6 months and 1 year. Results:the results show significant difference in Pain after one month (p=0.032), radiodensity (p=0.05), bone graft resorption (p=0.03) for 1 year follow-up in favor of the VBG group compared to the NVBG group, there was no statistical difference in bone graft failure, infection, speech and recurrence between the two groups. Conclusion: Vascularized bone graft is the method of choice, especially in extensive malignant defects. On the other hand, novascularized bone graft (81.2% success rate) is a suitable complementary flap for mandible reconstruction mainly in benign and healthy patients. For future studies, large sample size with long-term follow-up more than 1 year will be required to validate our study.

Systematic review and pooled analysis of survival rates, success, and outcomes of osseointegrated implants in a variety of composite free flaps

The aim of this review was to provide an update on survival rates of osseointegrated implants into common composite free flaps used for maxillary and mandibular reconstructions and identify factors affecting outcomes. PubMed, Medline, Embase, and Cochrane databases were searched. Included studies reported implant survival by flap type. Results were pooled and survival was estimated with the Kaplan-Meier method. Variables affecting survival were assessed using Cox regression. Thirty-two of the 2631 articles retrieved were included, totaling 2626 implants placed into fibula, iliac crest, scapula, and radial forearm free flaps. Pooled survival showed 94% 5-year survival of implants in fibula and iliac crest with no difference between groups (P = .3). Factors effecting survival included radiotherapy (HR 2.3, 95% CI 1.2-4.6, P = .027) and malignant disease (HR 2.2, 95%CI 1.6-3.1, P < .001). Implant survival appears adequate across common flap types; however, there are limited numbers reported in less common flaps.

Quantifying Aerosolization of Facial Plastic Surgery Procedures in the COVID-19 Era: Safety and Particle Generation in Craniomaxillofacial Trauma and Rhinoplasty

Background: COVID-19 poses a potentially significant infectious risk during procedures of the head and neck due to high viral loads in the nasal cavity and nasopharynx. Facial plastic surgery has significant exposure to these areas during craniomaxillofacial trauma procedures and rhinoplasty. Methods: Airborne particulate generation in the 1-10 μm range was quantified with an optical particle sizer in real time during cadaveric-simulated rhinoplasty and facial trauma conditions. Procedures tested included mandibular plate screw drilling, calvarial drilling, nasal bone osteotomy, nasal dorsal rasping, and piezoelectric saw use. Particulate generation was measured both adjacent to the surgical site and at surgeon mouth level (SML). Results: Mandibular plate screw drilling without irrigation generated significant particulate both adjacent to the surgical site and at SML (p < 0.01). Irrigation mitigated particulate generation at SML to nonsignificant levels. Calvarial drilling additionally produced substantial particulate above baseline adjacent to the surgical site (p < 0.01). Standard nasal osteotomies and dorsal rasping did not generate detectable airborne particulate, whereas piezoelectric saw use was associated with significant particulate generation both adjacent to the surgical site (p < 0.001) and at SML (p < 0.01). At SML, smaller particulate represented a significantly higher proportion of total particulate detected. Conclusions: The majority of craniomaxillofacial trauma procedures involve particle generation that may be limited in spread by the use of local irrigation. Most bony work involved in rhinoplasty can be safely performed without a high degree of particle formation. The use of piezoelectric instruments in rhinoplasty should be avoided when concerned for particulate generation.

The Anatomical Variation of the Scapular Spine in A Chinese Population

Background

The occurrence of fractures and risks following reverse total shoulder arthroplasty (rTSA) is common due to the variation of scapular spine (SS). Therefore, the consideration of the variable osteological features of SS prior to surgery may prove to be significant for the implementation of rTSA. This study aimed to propose a classification of SS through particular and quantitative parameters.

Material/Methods

In total, 354 intact dry scapulae were geometrical measured and classified on account of anatomical characteristics and the shapes of SS.

Results

Type I SS was found, and this was the most frequency was type (27.97%). The least common type was type II. The type of SS had a direct association with bone stock and bone mineral density. Type II represented an association with a much thinner spine and restricted cortical and cancellous bone; types II and V were also associated with a crooked SS, which had a more complex morphology.

Conclusions

This study offered a comprehensive classification of SS in the Chinese population. On the whole, this study indicates that knowledge of the morphological variations of SS can prompt the diagnosis of scapular fractures and can promote more successful rTSA procedures, and the relative clinical trial is necessary to support it.

3D Finite Element Study on: Bar Splinted Implants Supporting Partial Denture in the Reconstructed Mandible

AIM:

This study aimed to estimate the stress patterns induced by the masticatory loads on a removable prosthesis supported and retained by bar splinted implants placed in the reconstructed mandible with two different clip materials and without clip, in the fibula-jaw bone and prosthesis using finite element analysis.

METHODS:

Two 3D finite element models were constructed, that models components were modeled on commercial CAD/CAM software then assembled into finite element package. Vertical loads were applied simulating the masticatory forces unilaterally in the resected site and bilaterally in the central fossa of the lower first molar as 100N (tension and compression). Analysis was based on the assumption full osseointegration between different types of bones, and between implants and fibula while fixing the top surface of the TMJ in place.

RESULTS:

The metallic bar connecting the three implants is insensitive to the clips material. Its supporting implants showed typical behavior with maximum stress values at the neck region. Fibula and jaw bone showed stresses within physiologic, while clips material effect seems to be very small due to its relatively small size.

CONCLUSION:

Switching loading force direction from tensile to compression did-not change the stresses and deformations distribution, but reversed their sign from positive to negative.

Classification and Morphological Parameters of the Scapular Spine: Implications for Surgery

Incidence of scapular spine (SS) fractures as a result of complications of reverse total shoulder arthroplasty is relatively high leading to inferior clinical outcomes and an increased risk of revision and dislocation. Fractures of SS because of trauma, including the acromion, constitute 6% to 23% of scapula fractures. The purpose of this study was to classify the SS and present specific geometrical parameters according to osteologic features. A total of 319 intact dry scapulae were collected and classified based on morphological characteristics and shape of the SS. Nine bony landmarks were also chosen and described for their relevance to regions of interest for scapular fixation. Five specific types of SS were noted and the most prevalent groups were Type 1 (Fusiform shape) (47.17%) and Type 5 (Horizontal S-shape) (19.18%). Overall, Types 3, 4, and 1 showed thicker landmark values compared to Type 5, with Type 2 having smaller values. Our classification into 5 distinct types allowed appreciation of the anatomical variance of SSs. The contours of Types 5 and 1 presented a more complex morphology and may lead to a worse surgical approach due to a fracture. As Types 2 and 5 were much thinner than the other types, these may be more susceptible to fractures.

Comparison of Stresses Around Dental Implants Placed in Normal and Fibula Reconstructed Mandibular Models using Finite Element Analysis

PURPOSE

This study was formulated to evaluate and compare stresses around endosseous implants in various normal and fibula reconstructed mandibular models using finite element analysis method.

MATERIALS AND METHODS

CT scan data of a completely edentulous patient and a fibula reconstructed patient was made and the Dicom images were used to design 3-D mandibular models using software. Based on the information from the scan data, various types of reconstructed FEA models were made. Implants (fixtures) and superstructures were then embedded in each model and Von Mises stress around the neck of each implant under a vertical loading of 200 N and Horizontal load of 50 N was calculated using finite element structural analysis software. The results were compared between the reconstructed mandible and their respective normal mandible.

RESULTS

Higher stress values were obtained for all the reconstructed types under horizontal loading and in reconstructed models involving larger area of reconstruction the stress were more. In the models involving smaller area of reconstruction like symphysis alone or body alone there is no significant change in the stress values on vertical loading.

CONCLUSION

Stresses were comparatively smaller in mandibles involving a smaller area of reconstruction. Hence, fixed prosthesis could be advised and a bar retained over denture for reconstruction for larger area of reconstruction.

Three-dimensional finite element analysis of implant-supported crown in fibula bone model

PURPOSE

The purpose of this study was to compare stress distributions of implant-supported crown placed in fibula bone model with those in intact mandible model using three-dimensional finite element analysis.

MATERIALS AND METHODS

Two three-dimensional finite element models were created to analyze biomechanical behaviors of implant-supported crowns placed in intact mandible and fibula model. The finite element models were generated from patient's computed tomography data. The model for grafted fibula was composed of fibula block, dental implant system, and implant-supported crown. In the mandible model, same components with identical geometries with the fibula model were used except that the mandible replaced the fibula. Vertical and oblique loadings were applied on the crowns. The highest von Mises stresses were investigated and stress distributions of the two models were analyzed.

RESULTS

Overall stress distributions in the two models were similar. The highest von Mises stress values were higher in the mandible model than in the fibula model. In the individual prosthodontic components there was no prominent difference between models. The stress concentrations occurred in cortical bones in both models and the effect of bicortical anchorage could be found in the fibula model.

CONCLUSION

Using finite element analysis it was shown that the implant-supported crown placed in free fibula graft might function successfully in terms of biomechanical behavior.

Free fibular flap with periosteal excess for mandibular reconstruction

BACKGROUND

In microvascular transfer of fibular osteocutaneous flap for mandible reconstruction after cancer ablation, good bone union is necessary to allow timely radiation therapy after surgery. As the area of bone contact between fibula and the original mandible at the edge of the mandibular defect is small, a periosteal excess at both ends of the fibula covering the bone junction can be used to increase the chance of bone union. The purpose of this study is to investigate whether a periosteal excess surrounding both ends of the fibula flap can provide better blood supply and, therefore, ensure bone union and wound healing at 6 weeks after surgery and before radiation therapy initiation.

PATIENTS AND METHODS

The transfer of fibular osteocutaneous flap with periosteal excess was only applied to reconstruct segmental mandibular defects. As a consequence, only cases in which osteotomy of fibula was not performed were included in this study. A total of 34 fibular flaps without osteotomies were performed between 2000 and 2008; 17 with and 17 without the periosteal excess. The bone union was evaluated in terms of osseous callus formation using X-rays and CT three-dimensional images at 6 weeks after surgery, and results were assessed by three independent radiologists.

RESULTS

There was a significant difference between reconstructions with and without the periosteal excess in terms of bone union (P = 0.022). With reference to postoperative complications, the group reconstructed without periosteal excess presented a higher number of complications, mainly consisting of partial and total flap necrosis, respectively six (35.29%) and two (11.76%) cases. In the group reconstructed with periosteal excess, no loss of the skin island has occurred. A significant difference was observed in terms of partial flap necrosis (P = 0.024), while the other complications did not reveal a statistically significant difference (P > 0.05).

CONCLUSIONS

The use of a periosteal excess at both ends of the fibula flap provides better blood supply and is, therefore, able to ensure good bone healing and skin paddle survival regardless of the radiotherapy.

Implants in bone: part II. Research on implant osseointegration: material testing, mechanical testing, imaging and histoanalytical methods

PURPOSE

In order to determine whether a newly developed implant material conforms to the requirements of biocompatibility, it must undergo rigorous testing. To correctly interpret the results of studies on implant material osseointegration, it is necessary to have a sound understanding of all the testing methods. The aim of this overview is to elucidate the methods that are used for the experimental evaluation of the osseointegration of implant materials.

DISCUSSION

In recent decades, there has been a constant proliferation of new materials and surface modifications in the field of dental implants. This continuous development of innovative biomaterials requires a precise and detailed evaluation in terms of biocompatibility and implant healing before clinical use. The current gold standard is in vivo animal testing on well validated animal models. However, long-term outcome studies on patients have to follow to finally validate and show patient benefit.

CONCLUSION

No experimental set-up can provide answers for all possible research questions. However, a certain transferability of the results to humans might be possible if the experimental set-up is carefully chosen for the aspects and questions being investigated. To enhance the implant survival rate in the rising number of patients with chronic diseases which compromise wound healing and osseointegration, dental implant research on compromised animal models will further gain importance in future.

Sporicidal efficacy of genipin: a potential theoretical alternative for biomaterial and tissue graft sterilization

Terminal sterilization of musculoskeletal allografts by gamma radiation minimizes the risk of disease transmission but impairs allograft mechanical properties. Commonly employed crosslinking agents can sterilize tissues without affecting mechanical properties adversely; however, these agents are toxic. Genipin is reported to be a benign crosslinking agent that strengthens mechanical properties of tissues; however, the antimicrobial capacity of genipin is largely unknown. The present study's aims were: (1) to assess the sporicidal potential of genipin, (2) to improve antimicrobial capacity by changing chemical and physical treatment conditions. To establish genipin's sterilization potential Bacillus subtilis var. niger spore strips were treated with 0-10% genipin in PBS or in 1:1 DMSO:PBS up to 72 h at room temperature (RT). Sterilizing doses and concentrations of genipin were used to treat B. pumilus and Geobacillus stearothermophilus spores to assess broader spectrum sporicidal activity of genipin. Scanning electron microscopy (SEM) was performed to evaluate gross morphological changes after genipin treatment. Optimal sterilization conditions were determined by evaluating the effects of temperature (RT-50 °C), DMSO:PBS ratio (0:100-100:0), and treatment duration (24-72 h) on B. subtilis. Genipin penetration of full thickness bovine patellar tendon and cortical bone specimens was observed to assess the feasibility of the agent for treating grafts. Initial studies showed that after 72 h of treatment at RT with 0.63-10% genipin/DMSO:PBS B. subtilis spore strips were sterilized; 0.63% genipin/PBS did not sterilize spore strips at 72 h at RT. Genipin doses and concentrations that sterilized B. subtilis spore strips sterilized B. pumilus and G. stearothermophilus spore strips. SEM revealed no gross morphological differences between untreated and treated spores. Treatment optimization resulted in sterilization within 24 h with 100% PBS, and DMSO facilitated sporicidal activity. Genipin penetrated full thickness patellar tendon specimens and 3.72 ± 0.58 mm in cortical bone specimens. Genipin sterilizes B. subtilis, B. pumilus, and G. stearothermophilus spore strips. It penetrates soft and hard tissues at doses previously shown to be non-toxic and to improve mechanical strength in collagen-rich soft tissues. Further studies are indicated to assess genipin's effects on the mechanical properties of genipin-sterilized grafts, the ability of genipin to eradicate infectious species other than spores, and to assess whether sterilant activity persists after penetrating tissues and biomaterials.

Reconstruction of mandibular defects - clinical retrospective research over a 10-year period -

Backround

Functional and cosmetic defects in the maxillofacial region are caused by various ailments and these defects are addressed according to their need. Simplicity of procedure, intact facial function and esthetic outcome with the least possible donor site morbidity are the minimum requirements of a good reconstruction. Oro-mandibular reconstruction, although a challenge for the head and neck reconstructive surgeon, is now reliable and highly successful with excellent long-term functional and aesthetic outcomes with the use of autogenous bone grafts. Reconstruction of trauma- or mandibular oncologic defects with bony free flaps is considered the gold standard. However the the optimal reconstruction of mandibular defects is still controversial in regards to reconstructive options which include the donor site selection and the timing of surgery. The purpose of this study was to determine the outcome of different osseous reconstruction options using autogenous bone grafts for mandibular reconstructions.

Methods

This study was carried out on 178 patients with mandibular bone defects. They were reconstructed with autogenous bone grafts from different donor sites. At post operative visits they were evaluated for functional and cosmetic results.

Results

The success rate found in this study was around 90%. Only 7.6% of the cases showed poor results regarding facial contours and mouth opening. All other patients were satisfied with their cosmesis and mouth opening at the recipient sites was in the normal range during last follow-up visits. Donor sites were primarily closed in all cases and there was no hypertrophic scar.

Conclusion

Based on this study, autogenous bone grafts are a reliable treatment modality for the reconstruction of mandibular bone defects with predictable aesthetic and functional outcomes. As the free vascularized fibular flap has the least resorption and failure rate, it should be the first choice for most cases of mandiblular reconstruction.

Implant stability and peri-implant parameters in free vascularized iliac graft transplantation patients: report of three ameloblastoma cases

BACKGROUND

Ameloblastoma, a benign but locally aggressive tumor, accounts for 9% to 11% of all odontogenic tumors. Radical procedures, including resection, are performed. To restore functions after resection, free vascularized iliac grafts followed by a dental implant-supported prosthesis are used as a successful treatment option. The aim of this case report is to evaluate the peri-implant clinical status and stability of dental implants placed in patients with advanced-stage mandibular ameloblastomas.

METHODS

Examinations of three patients revealed extensive ameloblastomas, and hemimandibulectomies were performed. Six months after surgeries, two to four dental implants were placed. After 6 months of healing, one fixed prosthesis and two removable prostheses were delivered. The stability of implants was evaluated at the surgical baseline and 1, 3, 6, 9, and 12 months after surgery by resonance-frequency (RF) analysis. Peri-implant clinical parameters (i.e., plaque index [PI], gingival index [GI], gingival bleeding time index [GBTI], and peri-implant probing depth [PD]) were recorded at the delivery of the prosthesis and at follow-ups at 1, 3, and 6 months.

RESULTS

Nine implants that supported one removable prosthesis and two fixed prostheses were placed. RF analysis revealed no significant changes in implant stability during 12 months of follow-up. Peri-implant clinical parameters (PI, GI, and GBTI) showed slight improvements during follow-up. Although advancements were observed in 6 months, PDs were found to be deeper than optimal measurements for the whole observation time.

CONCLUSION

The implant-supported prosthetic rehabilitation of patients with ameloblastomas reconstructed with free vascularized iliac crest grafts can be a predictive alternative for improving the quality of life of patients in which a high implant stability and acceptable peri-implant health may be achieved.

Assessments of trabecular bone density at implant sites on CT images

OBJECTIVES

To evaluate the association between trabecular bone density measurements of potential implant sites made on axial DICOM images (DentaCT software) and on the same images with eFilm workstation, to correlate bone densities in Hounsfield units (HU) with subjective classification, and to establish a quantitative scale for each bone quality class.

STUDY DESIGN

Twenty-seven maxillary and 27 mandibular computed tomographic (CT) examinations of 75 potential implant sites were selected. Trabecular bone density was evaluated with DentaCT and eFilm. Bone quality was subjectively evaluated by 2 examiners. Descriptive statistics, between- and within-group comparison, correlation analysis, and Bland-Altman plot were used for data analysis.

RESULTS

DentaCT measurements were higher than eFilm (P < .001). Bone type 2 was the most prevalent, and bone density was significantly reduced from bone types 1 to 4. Quantitative parameters ranged as follows: bone type 4 <200 HU, bone types 2 and 3 >200 to <400 HU, and bone type 1 >400 HU.

CONCLUSION

Different qualities of bone can be found in any of the anatomical regions studied (anterior and posterior sites of maxilla and mandible), which confirms the importance of a site-specific bone tissue evaluation prior to implant installation.

Scapular thickness--implications for fracture fixation

The purpose of this study was to measure and map scapula osseous thickness to identify the optimal areas for internal fixation. Eighteen (9 pairs) scapulae from 2 female and 7 male cadavers were used. After harvest and removal of all soft tissues, standardized measurement lines were made based on anatomic landmarks. For consistency among scapulae, measurements were taken at standard percentage intervals along each line approximating the distance between two consecutive reconstruction plate screw holes. Two-mm-diameter drill holes were made at each point, and a standard depth gauge was used to measure thickness. The glenoid fossa (25 mm) displayed the greatest mean osseous thickness, followed by the lateral scapular border (9.7 mm), the scapula spine (8.3 mm), and the central portion of the body of the scapula (3.0 mm). To optimize screw purchase and internal fixation strength, the lateral border, the lateral aspect of the base of the scapula spine, and the scapula spine itself should be used for anatomic sites of internal fixation of scapula fractures.

Management of deficient anterior maxillary alveolus with mandibular parasymphyseal bone graft for implants

This paper discusses the use of autogenous bone graft from the symphyseal region of the mandible to widen the deficient anterior maxilla. Compressing short or narrow implants into deficient ridges is a poor technique that often fails to correctly replace ridge anatomy or afford stable restorations. Patients who were missing a maxillary incisor, and exhibiting a loss of supporting bone in the area, were found suitable for this technique. Ten patients were included in the study. In the anterior maxilla, the thin cortices can be split, and a corticocancellous bone graft from the mandibular symphyseal region can be positioned on the labial-buccal cortex. This surgical procedure enables implant placement in previously deficient bone within the maxilla. In comparison with other techniques, the use of a mandibular symphysis graft technique offers ease of access, good bone quantity for localized repair, a corticocancellous block graft morphology, low morbidity, decreased complaints of postoperative sensory disturbances and discomfort, and minimal graft resorption. An improved bone density results along with a shorter healing time as compared with other methods for bone repair. A success rate of 81.2% was obtained after a mean follow-up period of 3 years.