Analysis of outcome for elderly patients after microvascular flap surgery: a monocentric retrospective cohort study.

OBJECTIVES: Increasingly, aging societies pose a challenge, particularly in the most developed countries. This trend leads to an increasing group of old and very old patients presenting unique requirements and challenges. One of these challenges consists in reassessment and adaption of established treatment strategies for the elderly patients. There is an ongoing discussion taking place among cranio-maxillo-facial surgeons about the appropriate extent of reconstructive flap surgery for old patients. MATERIALS AND METHODS: This monocentric retrospective cohort study investigated 281 reconstructions with microvascular flaps by comparing the risk for a negative outcome, which was defined as revision, flap loss, and patient death, between three subgroups of elderly patients and younger patients. The three subgroups of elderly patients were defined as-1: young old (65-74 years), 2: old (75-84 years), and 3: oldest old (≥ 85 years). The group of the younger patients was defined by age between 50 and 64 years. Data were obtained within a defined period of 42 months. RESULTS: Significant correlations with a negative outcome were found for the variables stay on IMC/ICU, multiple flaps, and radiotherapy prior surgery. Our data showed no significant correlation between age and a higher risk for a negative outcome. CONCLUSION: Defect reconstruction with microvascular flaps in old patients is not related with a higher risk for a negative outcome. CLINICAL RELEVANCE: Independently of age, treatment with microvascular flaps is an option for all operable patients, with an indication for oncologic surgery. For optimal therapy planning, individual patient resources and preferences should be considered instead of chronologic age.

High-level ßIII-tubulin overexpression occurs in most head and neck cancers but is unrelated to clinical outcome.

BACKGROUND: ßIII-tubulin (TUBB3) is an isotype of microtubules, which are involved in crucial cellular roles including maintenance of cell shape, intracellular transport, and mitosis. Overexpression of TUBB3 was found to be associated with poor prognosis and resistance to tubulin-binding drugs and in several solid tumors including head and neck squamous cell carcinomas (HNSCC). Considering the potential high importance of a prognostic biomarker in these cancers, this study aimed to investigate the clinical relevance of immunohistochemical TUBB3 expression in HNSCC. METHODS: Tissue microarray (TMA) sections containing samples from 667 cancers of oral cavity, oro- and hypopharynx, and larynx for which follow-up data were available were analyzed for TUBB3 expression by immunohistochemistry. RESULTS: Over 90% of our analyzed cancers showed unequivocal cytoplasmic TUBB3 expression. Staining was considered weak in 69 (15.5%), moderate in 149 (33.5%), and strong in 188 (42.2%) of cancers. The frequent TUBB3 overexpression showed no significant correlation with pathological grading, tumor stage, nodal status, or surgical margin and had no impact on patient outcomes. CONCLUSION: Despite lacking prognostic utility in HNSCC, the remarkable high prevalence of TUBB3 expression in HNSCC emphasizes its putative relevance as a target for future drugs targeting TUBB3.

Lack of evidence for prognostic value of epidermal growth factor receptor intron-1 CA repeats for oral carcinomas.

Epidermal growth factor receptor (EGFR) expression is altered in several malignancies, including oral squamous cell carcinoma. A CA-repeat polymorphism in intron-1 (CA-SSR-1) of the EGFR gene is reported to influence EGFR expression and is associated with features of various solid tumors and outcomes of cancer patients. In the present study we evaluated the influence of length and zygosity of CA-SSR-1 on the survival of patients with oral squamous cell carcinoma. The length and zygosity of CA-SSR-1 was obtained through microsatellite analysis in 91 patients with oral cancer, who were treated in the Department of Oral and Maxillofacial Surgery of the University Medical Centre Hamburg Eppendorf, Germany, during the years 1998-2008. Follow up was conducted until 2016. Outcome measures were age, gender, tumor stage, occurrence of metastases, and date of recurrence or death. Statistical analysis was conducted using the chi-square test and the log-rank test. Neither length nor zygosity of the CA-SSR-1 in patients with oral squamous cell carcinoma was significantly correlated with sex, age, tumor size, tumor localization, lymph node involvement, metastasis status, disease-free survival, or overall survival. Length and zygosity of the CA-SSR-1 polymorphism in EGFR is not able to serve as a prognostic biomarker in White European patients with oral squamous cell carcinoma.

CD151 expression is frequent but unrelated to clinical outcome in head and neck cancer.

OBJECTIVES: CD151 is a plasma membrane protein belonging to the tetraspanin family. CD151 represents a putative therapeutic target and has been suggested as a prognostic marker in several cancer types. The present study aims to investigate the prognostic relevance of immunohistochemical CD151 expression in head and neck squamous cell carcinoma (HNSCC). MATERIALS AND METHODS: Tissue microarray (TMA) sections containing samples from 667 cancers of oral cavity, oro- and hypopharynx and larynx, for which follow-up data were available, were analyzed for CD151 expression by immunohistochemistry. RESULTS: Membranous CD151 immunostaining was recorded in 269 (60.3 %) of 446 analyzable cases. Staining was considered weak in 129 (28.9 %), moderate in 98 (22.0 %), and strong in 42 (9.4 %) of cancers. CD151 expression was unrelated to histological grade, tumor stage, nodal status, or surgical margin. There was a tendency towards a somewhat lower prevalence of CD151 expression in tumors of the oral cavity (52.9 % positive) as compared to cancers of the oro-hypopharynx (62.1 %) and larynx (63.3 %; p = 0.0100). CD151 expression had no impact on patient survival. CLINICAL RELEVANCE: In summary, immunohistochemical analysis of CD151 lacks prognostic utility in HNSCC. The high prevalence of CD151 expression in HNSCC emphasizes its putative relevance as a therapeutic target for further development of anti-CD151 drugs.

Postoperative bleeding risk for oral surgery under continued rivaroxaban anticoagulant therapy.

OBJECTIVES: The purpose of this study was to assess the risk of postoperative bleeding complications after oral procedures performed under continued mono or dual anticoagulation therapy with rivaroxaban (and aspirin). METHODS: This retrospective single-center observational study included 52 oral procedures performed under continued oral anticoagulant therapy with rivaroxaban (20 mg/day). Among them, two procedures were performed under continued dual therapy with aspirin (100 mg/day) added to the regimen. Postoperative bleeding events were compared with 285 oral procedures in patients without any anticoagulation/antiplatelet therapy. RESULTS: Postoperative bleeding complications after oral surgery occurred significantly more often in patients under continued rivaroxaban therapy (11.5 %) than in the control cases without anticoagulation/antiplatelet medication (0.7 %). All of the bleeding events were manageable: Two of them were treated with local compression, three by applying new fibrin glue with (one case) or without (two cases) secondary sutures, one occurred during a weekend and was therefore treated under inpatient conditions with suture replacement. All postoperative bleeding episodes occurred during the first postoperative week. CONCLUSIONS: According to our data, continued anticoagulation therapy with rivaroxaban significantly increases postoperative bleeding risk for oral surgical procedures, although the bleeding events were manageable. CLINICAL RELEVANCE: Oral surgeons, cardiologists, general physicians, and patients should be aware of the increased bleeding risk after oral surgical procedures. Close observation up to 1 week postoperatively is advisable to prevent excessive bleeding.

Linear accuracy and reliability of volume data sets acquired by two CBCT-devices and an MSCT using virtual models: a comparative in-vitro study.

OBJECTIVE: To discriminate clinically relevant aberrance, the accuracy of linear measurements in three-dimensional (3D) reconstructed datasets was investigated. MATERIALS AND METHODS: Three partly edentulous human skulls were examined. Landmarks were defined prior to acquisition. Two CBCT-scanners and a Quad-slice CT-scanner were used. Actual distances were physically measured with calipers and defined as a reference. Subsequently, from digital DICOM datasets, 3D virtual models were generated using maximum intensity projections (MIPs). Linear measurements were performed by semi-automated image analysis. Virtual and analogue linear measurements were compared using repeated measurements in a mixed model (p ≤ 0.05). RESULTS: No significant difference was found among all of the digital measurements when compared to one another, whereas a significant difference was found in matched-pairs analysis between CBCT and calipers (p = 0.032). All digitally acquired data resulted in lower mean values compared to the measurements via calipers. A high level of inter-observer reliability was obtained in the digital measurements (inter-rater correlation = 0.988-0.993). CONCLUSIONS: The reconstructed datasets led to highly consistent values among linear measurements. Yielding sub-millimeter precision, these modalities are assumed to reflect reality in a clinically irrelevant altered manner. During data acquisition and evaluation, a maximum of precision must be achieved.

Residual deficits in quality of life one year after intensity-modulated radiotherapy for patients with locally advanced head and neck cancer: Results of a prospective study.

PURPOSE: Patients with locally advanced head and neck cancer (LAHNC) undergo life-changing treatments that can seriously affect quality of life (QoL). This prospective study examined the key QoL domains during the first year after intensity-modulated radiotherapy (IMRT) and identified predictors of these changes in order to improve patient outcomes. PATIENTS AND METHODS: A consecutive series of patients with LAHNC completed the European Organisation for Research and Treatment of Cancer (EORTC) Quality of Life Questionnaire Core module (QLQ-C30) and the HNC-specific QLQ-HN35 before (t0) and at the end (t1) of definitive or adjuvant IMRT, then at 6-8 weeks (t2), 6 months (t3), and 1 year (t4) after IMRT. RESULTS: Patients (n = 111) completing questionnaires at all five time points were included (baseline response rate: 99%; dropout rate between t0 and t4: 5%). QoL deteriorated in all domains during IMRT and improved slowly during the first year thereafter. Many domains recovered to baseline values after 1 year but problems with smelling and tasting, dry mouth, and sticky saliva remained issues at this time. Increases in problems with sticky saliva were greater after 1 year in patients with definitive versus adjuvant IMRT (F = 3.5, P = 0.05). CONCLUSION: QoL in patients with LAHNC receiving IMRT takes approximately 1 year to return to baseline; some domains remain compromised after 1 year. Although IMRT aims to maintain function and QoL, patients experience long-term dry mouth and sticky saliva, particularly following definitive IMRT. Patients should be counseled at the start of therapy to reduce disappointment with the pace of recovery.

Virtual planning of complex head and neck reconstruction results in satisfactory match between real outcomes and virtual models.

OBJECTIVES: The reconstruction of large facial bony defects using microvascular transplants requires extensive surgery to achieve full rehabilitation of form and function. The purpose of this study is to measure the agreement between virtual plans and the actual results of maxillofacial reconstruction. MATERIALS AND METHODS: This retrospective cohort study included 30 subjects receiving maxillofacial reconstruction with a preoperative virtual planning. Parameters including defect size, position, angle and volume of the transplanted segments were compared between the virtual plan and the real outcome using paired t test. RESULTS: A total of 63 bone segments were transplanted. The mean differences between the virtual planning and the postoperative situation were for the defect sizes 1.17 mm (95 % confidence interval (CI) (-.21 to 2.56 mm); p = 0.094), for the resection planes 1.69 mm (95 % CI (1.26-2.11); p = 0.033) and 10.16° (95 % CI (8.36°-11.96°); p < 0.001) and for the planes of the donor segments 10.81° (95 % CI (9.44°-12.17°); p < 0.001) The orientation of the segments differed by 6.68° (95 % CI (5.7°-7.66°); p < 0.001) from the virtual plan; the length of the segments differed by -0.12 mm (95 % CI (0.89-0.65 mm); not significant (n.s.)), respectively, while the volume differed by 73.3 % (95 % CI (69.4-77.6 %); p < 0.001). The distance between the transplanted segments and the remaining bone was 1.49 mm (95 % CI (1.24-1.74); p < 0.001) and between the segments 1.49 mm (95 % CI (1.16-1.81); p < 0.001). CONCLUSIONS: Virtual plans for mandibular and maxillofacial reconstruction can be realised with excellent match. CLINICAL RELEVANCE: These highly satisfactory postoperative results are the basis for an optimal functional and aesthetic reconstruction in a single surgical procedure. The technique should be further investigated in larger study populations and should be further improved.

Immunohistochemical and FISH analysis of EGFR and its prognostic value in patients with oral squamous cell carcinoma.

OBJECTIVES: To study immunohistochemical expression of the epithelial growth factor receptor (EGFR) in oral carcinomas and the head and neck region to examine possible associations with various features of the tumors and survival of the patients. MATERIALS AND METHODS: Sections were made from two tissue arrays composed of 206 oral squamous cell carcinomas and 427 squamous cell carcinomas of the head and neck region, respectively, and examined for EGFR expression and Ki-67 labeling index by means of immunohistochemistry, and for EGFR gene amplification by means of fluorescence in situ hybridization. Correlation between resulting parameters and with clinical features was evaluated using chi-square test and Kaplan-Meyer analysis. RESULTS: A statistically significant association was observed for strong EGFR immunohistochemical (IHC) expression with advanced lymph node involvement (P = 0.02). EGFR immunohistochemical expression did not significantly correlate with patient disease specific (DS) or overall survival (OS). EGFR gene amplification was not correlated with any of the tumor features nor to survival of the patients (DS and OS). DISCUSSION: Epithelial growth factor receptor IHC expression and gene amplification might be suitable to predict locoregional control in oral squamous cell carcinoma patients but an inappropriate predictor for patients survival.

Her2 expression and gene amplification is rarely detectable in patients with oral squamous cell carcinomas.

PURPOSE: Her2 (ErbB2) transforms cells when overexpressed and is an important therapeutic target in breast cancer. Contrary to breast cancer, studies on Her2 overexpression and gene amplification in squamous cell carcinomas of the head and neck region described largely different results. This study was undertaken to learn more on the prevalence and clinical significance of HER2 amplification and overexpression in squamous cell carcinomas of the head and neck. MATERIALS AND METHODS: Her2 expression and gene amplification was analyzed by immunohistochemistry (IHC) and fluorescence in situ hybridization (FISH) on two tissue microarrays composed of 427 squamous cell carcinomas of the head and neck region and 222 oral squamous cell carcinomas. Results were compared with clinicopathological features. RESULTS: Her2 expression and gene amplification was rarely detectable in squamous cell carcinomas of the head and neck region and unrelated to tumor phenotype or survival of the patients with oral squamous carcinoma. DISCUSSION: Our results demonstrate that Her2 protein and gene amplification was only detectable in a small subset of squamous cell carcinomas of the head and neck region as well as oral squamous cell carcinomas. However, it can be speculated that those few patients with Her2 overexpressing and gene amplificated tumors may possibly benefit from an anti-Her2 therapy.

CCND1 amplification and cyclin D1 immunohistochemical expression in head and neck squamous cell carcinomas.

OBJECTIVES: Gene products, which show a significant association to cell proliferation and cell cycle control, are of high scientific interest, because genes as well as gene products could be possible targets for a specific therapeutic approach and eventually be prognostic markers. MATERIALS AND METHODS: Cyclin D1 expression and amplification as well as the Ki-67 expression status were examined in a two tissue microarray analysis for head and neck squamous cell carcinoma (HNSCC) including 546 patients. A tumour site-specific analysis and a survival analysis of 222 oral squamous cell carcinoma (OSCC) patients were performed. Cyclin D1 amplification status was examined with fluorescence in situ hybridisation analysis, while cyclin D1 expression and Ki-67 expression status were examined with IHC. RESULTS: Amplification of the CCND1 gene and immunohistochemical expression of cyclin D1 and Ki-67 were examined in 546 tumours of the head and neck region in two tissue microarrays. CCND1 amplification was significantly more frequent in pharyngeal carcinomas (63%) than in laryngeal (37%) and oral (25%) carcinomas. Among the 222 cases of OSCCs, both CCND1 amplification and cyclin D1 expression were significantly associated with overall survival of the patients (p = 0.0127 and p = 0.0004, respectively). Ki-67 expression was significantly associated with cyclin D1 expression and with amplification of the CCND1 gene (p = 0.0002 and p = 0.0015, respectively) but not with patient overall survival. CONCLUSION: Our results suggest the prognostic value of CCND1 amplification and cyclin D1 expression for patients with OSCC and highlight the genetic differences in HNSCC of different subanatomic localisation. CLINICAL RELEVANCE: Cyclin D1 expression and CCND1 amplification seem to have a prognostic value for OSCC. Further studies of HNSCC should always consider subanatomic genetic differences.

P53 immunohistochemical expression does not correlate with clinical features in 207 carcinomas of the oral cavity and in the head and neck region.

OBJECTIVES: The present study aims to investigate the relevance of immunohistochemical p53 expression in carcinomas of the oral cavity and of the head and neck region. Long-term clinical and histopathological follow-up findings as well as HPV status are correlated with the results of this examination. MATERIALS AND METHODS: Sections made from two tissue arrays composed of 222 oral squamous cell carcinomas and 427 squamous cell carcinomas of the head and neck region, respectively, were examined for p53 expression and Ki-67 index by means of immunohistochemistry. Correlation of long-term clinical findings of the patients and pathological features of tumours with laboratory results were examined statistically. RESULTS: No significant correlation was found between the p53 immunohistochemical expression in the 207 oral carcinomas and features of the tumours and patient outcomes. There was no significant association between the Ki-67 labelling index and the p53 expression. DISCUSSION: Our failure in detecting any association of the p53 immunohistochemical expression regardless of HPV status with clinical features of these tumours suggests it lacks a prognostic value for squamous cell carcinomas of the oral cavity. CLINICAL RELEVANCE: The prognostic value of p53 immunostaining in oral squamous carcinoma is not clarified yet. In the present study, there is no impact on any prognostical item nor even a correlation with cell proliferation (Ki-67) regardless of HPV status.

Imaging of the midfacial and orbital trauma.

The severity of midfacial and orbital injuries depends on the one hand on cause, force vector, load point, or area and on the other hand on the bony and soft tissue resistance as well as individual anatomy. These variables result in a variety of possible injuries of the midfacial and orbital complex. The time critical choice of an adequate imaging modality of these injuries is influenced by the possible severity of concomitant injuries. Besides the confirmation of a clinical diagnosis, the need for high-resolution three-dimensional imaging for preoperative planning of facial reconstruction using intraoperative navigation has become more and more important in the past years. To achieve optimal functional and esthetic outcomes, the anatomical complexity of the midface has to be addressed and the adequate imaging modality has to be chosen keeping the upcoming surgical treatment in mind. The current imaging modalities for midfacial and orbital trauma are presented and critically evaluated depending on the indications. Furthermore, new strategies to support surgeons in achieving best possible midfacial reconstructions are discussed. An algorithm to choose the adequate imaging modality in midfacial and orbital traumatology is provided.

Immunohistochemical analysis of p16 expression, HPV infection and its prognostic utility in oral squamous cell carcinoma.

OBJECTIVES: Functional inactivation of p16 is an early and frequent event in the carcinogenesis of tumours of the head and neck region. However, the prognostic relevance of p16 protein expression for these tumours has been controversial. This study aims to examine immunohistochemical expression of p16 and HP virus in a large number of oral carcinomas, and possible correlation with clinical features of the tumours and survival of the patients. METHODS: Two tissue microarrays composed of 222 oral carcinomas and 427 squamous cell carcinomas of the head and neck region were used for this study. Sections were stained immunohistochemically (anti-p16), and PCR analysis (HPV status) was carried out. Correlation of p16 expression/HPV status with features of tumours and with survival of the patients was analysed by means of Chi-squared test and using Kaplan-Meier analysis, respectively. RESULTS: p16 expression was found immunohistochemically in 74% of tumours, but was not significantly correlated with features of the tumours, but recurrence-free survival of the patients (P = 0.009) if located predominantly nuclear. On the other hand neither intensity of p16 expression (P = 0.41) nor HPV status (P = 0.82) had any effect on these two aspects. CONCLUSION: Immunohistochemical expression of p16 alone provides a limited tool for diagnosis and prognosis of carcinomas of the head and neck region. Immunohistochemical analysis of p16 depending on its intracellular location might serve as a surrogate marker for HPV infection.

Leech therapy in reconstructive maxillofacial surgery.

PURPOSE: Corrective plastic surgery is indicated after accidents, burns, cancer surgery, or postoperative wound healing disorders with large tissue defects. The range of reconstructive techniques includes local skin flaps, pedicle grafts, and microvascular anastomosed flaps in the case of large defects. Main complications such as arterial and venous insufficiency caused by a vessel collapse or a vascular spasm are reported regularly in the area of anastomosed vessels and are the concern of any surgeon. Today, leeches are used if wound healing is at risk because of hemodynamic imbalance or a venous insufficiency. PATIENTS AND METHODS: A retrospective evaluation of 148 patients who underwent medical leech therapy in the case of local or pedicaled flaps and some patients who had undergone reconstruction with microvascular flaps from 2005 and 2010 was conducted. Our sample had the typical symptoms of venous congestions of their flaps, despite suture removal, relief of pressure on the flap, and the elimination of a hematoma beyond the flap after surgery. Medical leech therapy was used in these cases. RESULTS: Our series has confirmed the excellent and predictable healing after medical leech therapy for local and microsurgical anastomosed flaps in the case of venous congestion. CONCLUSION: Leech therapy should be considered as a reliable additional procedure and an advantage in maxillofacial and plastic reconstructive surgery to remedy complications resulting from a hemodynamic imbalance or venous insufficiency in the immediate postoperative period.

Current concepts in cleft care: A multicenter analysis.

The current surgical techniques used in cleft repair are well established, but different centers use different approaches. To determine the best treatment for patients, a multi-center comparative study is required. In this study, we surveyed all craniofacial departments registered with the German Society of Maxillofacial Surgery to determine which cleft repair techniques are currently in use. Our findings revealed much variation in cleft repair between different centers. Although most centers did use a two-stage approach, the operative techniques and timing of lip and palate closure were different in every center. This shows that a retrospective comparative analysis of patient outcome between the participating centers is not possible and illustrates the need for prospective comparative studies to establish the optimal technique for reconstructive cleft surgery.

Immediate loading of subcrestally placed dental implants in anterior and premolar sites.

PURPOSE: Immediate loading of dental implants has been evolving into an appropriate procedure for the treatment of partially edentulous jaws. The purpose of this study was to evaluate the clinical success and radiological outcome of immediately and delayed loaded dental implants in anterior and premolar sites. MATERIALS AND METHODS: In this retrospective study, data of 163 individuals requiring tooth removal with subsequent implant placement in anterior and premolar sites were analyzed. Implants were immediately loaded by provisional acrylic resin bridges or loaded with delay. Implants were followed up annually for up to 9 years including intraoral radiographs. RESULTS: A total of 285 implants in 163 patients were placed. 218 implants were immediately loaded and 67 implants with delay. Fifteen implants failed during the follow-up period resulting in survival rates of 94.5% for immediate loading and 95.5% for delayed loading. After an initial decrease of 0.3 mm in the first 12 months the marginal bone level remained stable. No statistically significant differences were found in marginal bone loss between immediately and delayed loaded implants (P = 0.518, 95% CI). CONCLUSION: Within the limits of this study, immediate loading of immediately subcrestally placed dental implants in anterior and premolar sites is a reliable treatment option for dental rehabilitation.

Biocompatibility and Osseointegration of Titanium Implants with a Silver-Doped Polysiloxane Coating: An In Vivo Pig Model.

PURPOSE: To test the antimicrobial properties, surface topography, reaction of surrounding tissue (biocompatibility), and osseointegration of ultrathin implant surfaces containing polysiloxane and nanoscaled silver particles. MATERIALS AND METHODS: Implants with polysiloxane coating and nanoscaled silver particles (Ag/SiOxCy; HyProtect, Bio-Gate) were compared with implants with polysiloxane coating alone and with noncoated (grit-blasted and acid-etched) implants. A total of 72 implants were inserted into the calvaria of eight domestic pigs (nine implants each, three of each type). After 3 months, histologic sections were evaluated for inflammatory cell infiltration and bone implant contact. RESULTS: Roughness parameters did not differ between all three implant types. The Ag/SiOxCy coating exhibited a good antimicrobial effect in vitro and no sign of inflammatory cell infiltration in vivo. The noncoated implants demonstrated 10.85% and 14.48% more bone contact than the polysiloxane-coated implants (P = .003) and the Ag/SiOxCy­coated implants (P ≤ .001), respectively. Osseointegration was not significantly different between the Ag/SiOxCy­coated and polysiloxane-coated implants (P = .72). CONCLUSION: The osseointegration capability of the Ag/SiOxCy-coated implants was equal to that of the polysiloxane-coated implants but less than that of the grit-blasted and acid-etched implants. Because of the biocompatibility of the polysiloxane coating, further studies should be conducted in load-bearing models and in the oral cavity to investigate the antimicrobial effect of the embedded silver clusters.

Accuracy of Bone Measurements in the Vicinity of Titanium Implants in CBCT Data Sets: A Comparison of Radiological and Histological Findings in Minipigs.

PURPOSE: The aim of this animal study was the determination of accuracy of bone measurements in CBCT (cone-beam computed tomography) in close proximity to titanium implants. MATERIAL AND METHODS: Titanium implants were inserted in eight Göttingen minipigs. 60 implants were evaluated histologically in ground section specimen and radiologically in CBCT in regard to thickness of the buccal bone. With random intercept models, the difference of histologic measurements and CBCT measurements of bone thickness was calculated. RESULTS: The mean histological thickness of the buccal bone was 5.09 mm (CI 4.11-6.08 mm). The four raters measured slightly less bone in CBCT than it was found in histology. The random effect was not significant (p value 1.000). Therefore, the Intraclass Correlation Coefficient (ICC) was 98.65% (CI 100.00-96.99%). CONCLUSION: CBCT is an accurate technique to measure even thin bone structures in the vicinity of titanium implants.

Novel silk protein barrier membranes for guided bone regeneration.

This study assesses the biocompatibility of novel silk protein membranes with and without modification, and evaluates their effect on facilitating bone formation and defect repair in guided bone regeneration. Two calvarian bone defects 12 mm in diameter were created in each of a total of 38 rabbits. Four different types of membranes, (silk-, hydroxyapatite-modified silk-, ß-TCP-modified silk- and commonly clinically used collagen-membranes) were implanted to cover one of the two defects in each animal. Histologic analysis did not show any adverse tissue reactions in any of the defect sites indicating good biocompatibility of all silk protein membranes. Histomorphometric and histologic evaluation revealed that collagen and ß-TCP modified silk membranes supported bone formation (collagen: bone area fraction p = 0.025; significant; ß-TCP modified silk membranes bone area fraction: p = 0.24, not significant), guided bone regeneration and defect bridging. The bone, which had formed in defects covered by ß-TCP modified silk membranes, displayed a more advanced stage of bone tissue maturation with restoration of the original calvarial bone microarchitecture when compared to the bone which had formed in defects, for which any of the other test membranes were used. Micro-CT analysis did not reveal any differences in the amount of bone formation between defects with and without membranes. In contrast to the collagen membranes, ß-TCP modified silk membranes were visible in all cases and may therefore be advantageous for further supporting bone formation beyond 10 weeks and preventing soft tissue ingrowth from the periphery. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2603-2611, 2017.