The risk of tooth root injuries using cortical screws for intermaxillary fixation and osteosynthesis plates - A retrospective analysis.

Intermaxillary fixation (IMF) and osteosynthesis plates (OP) are widely used for the non-surgical and surgical treatment of mandible and condyle fractures. The aim of this retrospective study was to analyze the frequency of tooth root injuries by IMF and OP screws. Electronic patient reports (2004-2013) were screened for patients treated with either IMF screws and/or OP in the Department of Oral- and Maxillofacial Surgery, University Medical Center Mainz, Germany. The frequency and the position of endangered and injured teeth were analyzed by orthopantomogram (OPTG) and cone beam computer tomography (CBCT). Next, possible predictive factors for tooth root injuries, namely interdental- and crestal distance, screw length and distance between tooth root and screw were evaluated. Further, the accuracy of OPTG vs. CBCT concerning the diagnosis of tooth root injuries was analyzed. Three-hundred sixty-six patients were included and 3388 teeth were defined as endangered by IMF- and OP screws. Overall, 16 injured teeth (0.5%) in 13 patients (3.55%) were detected. Nine injuries (56.3%) were caused by IMF- and seven injuries (43.8%) by OP screws. Three teeth were non-vital, one tooth had to be extracted. No correlation between the predictive factors crestal distance, screw length and tooth root injuries was found. If tooth injury occurred, a significant correlation between the interdental distance and the distance between tooth root and screw was found (κ = 0.48; p < 0,0001). Comparison between OPTG vs. CBCT demonstrated that many of the injuries that were seen in the OPTG (n = 230) could not be verified in the CBCT scans (n = 16) (κ = 0.12). To conclude, screws for IMF and OP can be considered as a safe procedure concerning the risk of tooth root injuries.

Biofunctionalization of synthetic bone substitutes with angiogenic stem cells: Influence on regeneration of critical-size bone defects in an in vivo murine model.

PURPOSE: The aim of this study was to investigate the influence of human bone marrow-derived endothelial progenitor cells (EPC) on vascularization and bone regeneration in combination with a bone-substitute material (BSM) in a critical-size bone defect in a murine model. Critical-size bone defects were performed and the defects were filled according to the group membership. MATERIALS AND METHODS: Eighteen rats were randomized in two experimental groups: BSM (BoneCeramic) with/without EPC biofunctionalization, and a control group without BSM and EPC. Calvaria bone defects were performed and the defects were filled according to the group membership. After 8 weeks, qualitative tissue response of newly formed bone mass was analyzed by histology, cone beam CT (CBCT) and micro-CT (µCT) scans. Occurrence of tumor masses due to EPC vascularization in peripheral organs was investigated microscopically in histological slides of liver and kidney. RESULTS: The combination of EPC and BSM showed smaller bone defects in the CT scans and the histological evaluation as the single use of BSM without EPC by trend (p = 0.067). Further, a higher amount of blood vessels could be found in histological slices of BSM in combination with EPC. No inflammatory response or tumor formation could be found. CONCLUSION: These findings confirm the biocompatibility of the used BSM and provide evidence that the combination of BSM with EPC might be effective for bone vascularization and regeneration. Using EPC in augmentation sites might overall lead to faster and better bone regeneration and should be further investigated in future studies.

Vascular architecture in free flaps: Analysis of vessel morphology and morphometry in murine free flaps.

The aim of this study was to analyze the development of vascular architecture as well as vascular morphometry and morphology of anastomosed microvascular free flaps. Free pectoral skin flaps were raised in 25 rats and anastomosed to the femoral vessels in the groin region. CD31 immunohistology was performed after 3, 7 and 12 d (each 5 animals each) to analyze microvessel density (MVD), microvessel area (MVA) and microvessel size (MVS). Microvascular corrosion casting was performed after 7 and 12 d (5 animals each) to analyze vessel diameter (VD), intervascular distance (IVD), interbranching distance (IBD), and branching angle (BA). Further on, sprout and pillar density as hallmarks of sprouting and intussusceptive angiogenesis were analyzed. Pectoral skin isles from the contralateral side served as controls. A significantly increased MVD was found after 7 and 12 d (p each <0.001). MVA was significantly increased after 3, 7 and 12 d (p each <0.001) and a significantly increased MVS was analyzed after 3 and 7 d (p each <0.001). VD and IVD were significantly increased after 7 and 12 d (p each <0.001). For IBD, a significantly increase was measured after 7 d (p < 0.001). For IBA, sprout and pillar density, no significant differences were found (p each ≥0.05). Significant changes in the vascular architecture of free flaps after successful microvascular anastomosis were seen. Since there was no evidence for sprout and pillar formation within the free flaps, the increased MVD and flap revascularization might be induced by the receiving site.

Effects of an oral bisphosphonate and three intravenous bisphosphonates on several cell types in vitro.

OBJECTIVE: To analyze the influence of an oral bisphosphonate and compare the potency to intravenous bisphosphonates on various cell types as regards the rarity of bisphosphonate-associated osteonecrosis of the jaw (BP-ONJ) caused by oral bisphosphonate. MATERIALS AND METHODS: A viability assay (MTT), a migration assay (Boyden chamber), and an apoptosis assay (Caspase-Glo® 3/7) were performed to analyze the effect of bisphosphonates on human fibroblasts, umbilical vein endothelial cells (HUVEC), and osteoblasts. RESULTS: Alendronate and intravenous bisphosphonates suppressed cell viability and migration, and induced apoptosis in all tested cell types. Alendronate had a greater impact than ibandronate on the characteristics in fibroblasts and osteoblasts but not as strong as zoledronate. CONCLUSIONS: The incidence of BP-ONJ in oral bisphosphonate treatment is reported to be much lower than that in intravenous bisphosphonates. However, the influences of alendronate on human cells were at least as strong as ibandronate, although it was lower than zoledronate. CLINICAL RELEVANCE: Alendronate showed strong enough effects to suppress human somatic cells and was comparable to certain intravenous bisphosphonates in potency. This study suggests that the lower incidence of BP-ONJ in alendronate treatment is not originated by its potency, but might be due to the low bioavailability of alendronate, lower dosing on a daily basis, and having no additional therapies.

Early cell response of osteogenic cells on differently modified implant surfaces: Sequences of cell proliferation, adherence and differentiation.

OBJECTIVES: Osseointegration of dental implants is a crucial prerequisite for long-term survival. Therefore, surface modifications are needed to interact with the extracellular environment and to trigger osteogenic cell responses such as cell proliferation, adherence, and differentiation. The purpose of this study was to investigate different surface modifications in vitro over 2 weeks. MATERIALS AND METHODS: Commercially available cells from a human osteogenic cell line (HHOB-c) were cultivated on the following surfaces: titanium with smooth surfaces (polished titanium (P), machined titanium (M), polyetheretherketone (Peek)), titanium with rough and hydrophilised surfaces (acid etched titanium (A), sandblasted acid etched titanium (SA and SA2), sandblasted acid etched hydrophilised (SAH), titanium plasma painted titanium (TPS)), titanium with calcium phosphate-containing surfaces (titanium plasma painted calcium phosphate modified titanium (TPS-CaP), sandblasted calcium phosphate modified titanium (S-CaP), sandblasted acid etched calcium phosphate modified titanium (SA-CaP)), and zirconium-oxide (yttrium amplified zirconium (Z), yttrium amplified Ca2+ delivering zirconium (Z-Ca)). Tissue culture polystyrene (TCPS) served as a control. Cell count was assessed after 24 h, 48 h, 72 h, 7 d, and 14 d; osteogenic cell adherence and differentiation were analysed by using cellular Quantitative Immuno-Cytochemistry (QIC) assay for alkaline phosphatase (AP), osteocalcin (OC), integrin alpha V (ITGAV), and talin (T). RESULTS: All tested surfaces showed a positive influence on the differentiation and adherence of osteogenic cells, especially P, M, A, TCPS, and Peek. After 48 h, the surfaces M, SA and SAH had induced a positive influence on adherence, whereas SA2, SA, and SAH triggered proliferation after 14 d. CONCLUSIONS: Rough and hydrophilised surface modifications, such as SAH, trigger osteogenic cell responses. These in vitro results highlight the potential use of SAH surface modifications of dental implants and indicate further clinical studies are warranted.

Biofunctionalization of porcine-derived collagen matrix using enamel matrix derivative and platelet-rich fibrin: influence on mature endothelial cell characteristics in vitro.

OBJECTIVES: The present study evaluated the effect of an enamel matrix derivative (EMD) and platelet-rich fibrin (PRF)-modified porcine-derived collagen matrix (PDCM) on human umbilical vein endothelial cells (HUVEC) in vitro. MATERIALS AND METHODS: PDCM (mucoderm®) was prepared to 6 mm (±0.1 mm) diameter discs. PDCM samples were incubated with either EMD, PRF, or control solutions for 100 min at 4 °C before the experiments. Cell-inducing properties of test materials on HUVEC cells were tested with cell proliferation assays (MTT, PrestoBlue®), a cytotoxicity assay (ToxiLight®), a Boyden chamber migration assay, and a cell attachment assay. Scanning electron microscopy (SEM) imaging was performed to determine the surface and the architecture of the modified matrices. RESULTS: Cell proliferation was elevated in the EMD and PRF groups compared with control (p each ≤0.046). PRF modification increased HUVEC migration ability by 8-fold compared with both control and EMD groups (p each <0.001). Both treatments significantly promoted the cell attachment of HUVEC to PDCM, as assessed by direct cell counts on the matrices (p each <0.001). CONCLUSIONS: HUVEC cell characteristics were overall improved by EMD- and PRF- modified PDCM. Adsorbed bioactive molecules to the PDCM surface may have contributed to a more preferable environment to surrounding cells. CLINICAL RELEVANCE: The results may give evidence that PDCM modification with EMD or PRF, respectively, might be a useful approach to improve clinical outcomes, to prevent inflammatory reactions and wound-healing disturbances, and to expand the clinical application area of PDCM.

Biomarkers in diagnosis and therapy of oral squamous cell carcinoma: A review of the literature.

Oral squamous cell carcinoma (OSCC) represents the sixth most common cancer, accounting for 2-4% of all malignancies worldwide. The overall survival rate of less than 60% remains generally poor, with prognosis heavily relying on the TNM staging system. Tumor size as well as the presence and extent of lymph node metastases are widely recognized as the most important predictors. However, the underlying mechanisms that lead to an aggressive phenotype are not yet fully understood. Therefore, possible biomarkers are much in need to predict prognosis, to help individualize therapy approaches, and to overcome possible resistance mechanisms. Despite a multitude of recently published biomarkers for OSCC, there is still an ongoing debate regarding their implementation in the clinical workflow. Thus, a systematic literature search via PubMed was performed to update the current literature with the latest evidence. In total, 128 studies were included and over 100 different biomarkers evaluated with reference to their influence of survival, tumor recurrence, advanced grading and lymph node metastasis. In this review, we highlight the important molecular mechanism underlying possible markers in tissue, blood or saliva samples for OSCC. As a major result, no clinical trials could be obtained to prove clinical importance of the validated predictors for survival, tumor recurrence, lymph node metastasis and therapy resistance. Therefore, further clinical investigations are much needed.

Diagnosing oral squamous cell carcinoma: How much imaging do we really need? A review of the current literature.

Complementary imaging techniques that round out the clinical examination are fundamentally important in the work-up of patients with oral squamous cell carcinoma (OSCC). Above all, exact determination of primary tumour extent, metastatic spread, and treatment response highly depend on accurate imaging methods. Despite a multitude of recently published reviews, there is still an ongoing debate regarding the best imaging method. In order to update the current literature with the latest evidence, a systematic literature search via Pubmed was performed. In total, 56 studies were enrolled, 4170 patients were analysed, and twenty different imaging methods were evaluated referring to their sensitivity, specificity, accuracy, positive predictive value (PPV), and negative predictive value (NPV). In summary, CT (computed tomography) and MRI (magnetic resonance imaging) currently remain the gold standard for evaluating extension of the primary tumour site. No additional evidence could be obtained for functional imaging methods displaying metastatic spread in the cervical lymph nodes, but was found for distant metastases. Furthermore, functional imaging seems to be beneficial in evaluating treatment response. There is further evidence in the accuracy of the different imaging methods found in this update that could possibly be implemented into the revision of the current guidelines and obtain a clear and coherent approach in the clinical set-up.

Lactate as a predictive marker for tumor recurrence in patients with head and neck squamous cell carcinoma (HNSCC) post radiation: a prospective study over 15 years.

OBJECTIVES: Lactate as a key regulator of the glycolytic phenotype has been recently described in fueling tumor growth and metastatic spread in head and neck squamous cell carcinoma (HNSCC). However, in context of tumor recurrence following adjuvant radiation, the underlying mechanisms remain uncertain. We therefore investigate the role of lactate towards radioresistance in HNSCC in this prospective study for the first time in vivo. MATERIALS AND METHODS: Herein, we analyzed biopsies of primary squamous cell carcinoma after surgery and adjuvant irradiation in 17 patients. Tumor tissue levels of ATP, glucose, and lactate were detected using induced metabolic bioluminescence imaging (imBI) and correlated with clinical data within an observation period of up to 15 years. RESULTS: High amounts of lactate levels in tumors of HNSCC are significantly negatively correlated with overall patient survival. Moreover, high expression of lactate in a primary tumor site is significantly correlated with tumor recurrence post radiation, whereas ATP and/or glucose showed no such correlation. CONCLUSION: Lactate can be seen not only as a waste product of altered glycolytic metabolism but also as a key master of malignancy as well as resistance mechanism towards irradiation. CLINICAL RELEVANCE: High expression of lactate levels in tumor tissue, obtained by metabolic bioluminescence imaging, may therefore serve as a predictor for overall and recurrence-free survival and could represent a future biomarker in the validation of adjuvant irradiation.

Influence of porcine-derived collagen matrix on endothelial progenitor cells: an in vitro study.

Porcine-derived collagen matrix (PDCM) has been reported as a promising alternative to autogenous soft tissue grafts in periodontal plastic surgery. The aim of this study was to analyze the influence of a novel PDCM on endothelial progenitor cells (EPC) in vitro. EPC were isolated from human peripheral blood, cultured and transferred on the PDCM (mucoderm®). Tissue culture polystyrene surface (TCPS) served as control. Cell viability of EPC on PDCM was measured by a MTT and PrestoBlue® assay. Migration ability was tested using a Boyden migration assay. A ToxiLight® assay was performed to analyze the influence of PDCM on adenylate kinase (ADK) release and apoptosis rate of EPC. Using the MTT assay, EPC cultured on PDCM demonstrated a significantly increased cell viability compared to the control group at days 3, 6 and 12 (p each <0.001). According to the PrestoBlue® assay, EPC showed a significant increase of cell viability compared to the control group at 48, 72, and 96 h (p each <0.001). In the Boyden migration assay, a significantly increased EPC migration ability could be observed after 3-12 days (p each ≤0.001). No significantly increased apoptosis rate of EPC on PDCM could be observed with exception after 96 h (p each >0.05). Overall, our results suggest a good biocompatibility of PDCM without any cytotoxic effects on EPC, which might support a rapid revascularization and therefore a sufficient ingrowth of the PDCM.

Angiogenesis in the Development of Medication-Related Osteonecrosis of the Jaws: An Overview.

Medication-related osteonecrosis of the jaws (MR-ONJ) is one of the most relevant side effects of bisphosphonate therapy; it is clinically defined as a non-healing wound in combination with an avascular and necrotic jaw within ongoing bisphosphonate therapy or after completed bisphosphonate therapy. Different theories concerning the development of MR-ONJ have been reported, while the exact pathophysiology is still unknown. Recent studies have increasingly focused on angiogenesis and revascularization concerning MR-ONJ pathophysiology, which seems to be a relevant factor in the development of MR-ONJ and a possible and promising point of action for MR-ONJ prevention and therapy. Therefore, and with respect to the different aspects and specific forms of angiogenesis, the enclosed review summarizes the possible role of angiogenesis and revascularization in the pathophysiology of MR-ONJ. Special focus is given to the strong negative influence of bisphosphonates on progenitor and mature endothelial cells in vitro as well as on microvessel sprouting in vitro and in vivo, which might result in overall reduced wound healing of oral soft and hard tissues, and therefore in an exposed and avascular jaw from a clinical viewpoint. Further, it will be summarized whether and in what way the aspect of angiogenesis might be used for possible MR-ONJ prevention and therapy.

Modified free pectoral skin flaps in rats.

Various types of murine free flaps have been developed for microsurgical training and research. We present a new modification of the free pectoral skin flap in Sprague-Dawley rats. Twelve free pectoral skin flaps were raised according to the standard protocol except that we deviated from it by transecting the common thoracic vessels at the origin of the axillary vessels and anastomosing them end-to-side to the femoral vessels in the groin. This reduced operating time and complications as well as postoperative morbidity and mortality. Overall, it simplified the procedure considerably and therefore made the model more attractive to beginners in microvascular surgery.

The influence of geranylgeraniol on human oral keratinocytes after bisphosphonate treatment: An in vitro study.

This in vitro study analyzed the influence of geranylgeraniol (GGOH) on human oral keratinocytes (HOK) after exposure to bisphosphonates. HOK were incubated with four different bisphosphonates (clodronate, ibandronate, pamidronate, zoledronate) in two experimental set-ups: with and without GGOH. MTT and PrestoBlue assays were used to analyze HOK cell viability. HOK migration ability was examined with Boyden and Scratch assays, and Tunel and ToxiLight assays were used to detect the HOK apoptosis rate. No significant differences between the experimental set-ups, with and without GGOH, could be found for clodronate (p each >0.3). For the nitrogen-containing bisphosphonates, negative effects could be shown in the experimental set-ups without GGOH in all assays. In the GGOH experimental set-ups, the levels of HOK cell viability were significantly increased (MTT: p each ≤0.001; PrestoBlue: p each ≤0.012). The HOK migration ability was also greater (Boyden: p each <0.001; Scratch: p each ≤0.015). Regarding the apoptosis rate, reduced numbers of apoptotic HOK in the Tunel assay (p each <0.001) and decreased adenylate kinase release in the ToxiLight assay (p each ≤0.002) were observed. GGOH reversed the negative effects of bisphosphonates on HOK. These findings provide evidence that GGOH could be a promising treatment option for BP-ONJ.

Analysis of implant-failure predictors in the posterior maxilla: a retrospective study of 1395 implants.

The aim of this study was to analyze predictors for dental implant failure in the posterior maxilla. A database was created to include patients being treated with dental implants posterior to the maxillary cuspids. Independent variables thought to be predictive of potential implant failure included (1) sinus elevation, (2) implant length, (3) implant diameter, (4) indication, (5) implant region, (6) timepoint of implant placement, (7) one-vs. two-stage augmentation, and (8) healing mode. Cox regression analysis was used to evaluate the influence of predictors 1-3 on implant failure as dependent variable. The predictors 4-9 were analyzed strictly descriptively. The final database included 592 patients with 1395 implants. The overall 1- and 5-year implant survival rates were 94.8% and 88.6%, respectively. The survival rates for sinus elevation vs. placement into native bone were 94.4% and 95.4%, respectively (p = 0.33). The survival rates for the short (<10 mm), the middle (10-13 mm) and the long implants (>13 mm) were 100%, 89% and 76.8%, respectively (middle-vs. long implants p = 0.62). The implant survival rates for the small- (<3.6 mm), the middle- (3.6-4.5 mm) and the wide diameter implants (>4.5 mm) were 92.5%, 87.9% and 89.6%, respectively (p = 0.0425). None of the parameters evaluated were identified as predictor of implant failure in the posterior maxilla.

Paraoxonase-2 (PON2) protects oral squamous cell cancer cells against irradiation-induced apoptosis.

PURPOSE: Patients with oral squamous cell carcinomas (OSCC) often receive radiotherapy to preferentially induce apoptosis of cancer cells through generation of overwhelming DNA damage. This is amplified by generation of reactive oxygen species (ROS), thereby causing oxidative stress and cell death. However, tumors resist through different mechanisms, including upregulation of anti-apoptotic factors and enhanced ROS resistance. We recently reported that the antioxidative enzyme PON2 significantly enhances cellular stress resistance by attenuating mitochondrial ROS-mediated apoptosis. Further, PON2 is often upregulated in cancer. This prompted us to investigate its yet unknown role in the protection of OSCC against irradiation-induced cell death. METHODS: PON2 expression was determined after 7 Gy singular irradiation in four OSCC cell lines (PCI-13, PCI-52, SCC-4, SCC-68) accompanied by the detection of caspase 3/7 activity. A direct role of PON2 was tested by siRNA-mediated knockdown. In vivo PON2 expression was tested in five patients with oral carcinoma and compared with healthy mucosa for the evaluation of clinical significance. RESULTS: PON2 is variably expressed in OSCC in vitro and in vivo. Compared with the other cell lines, SCC-4 cells showed twofold more basal PON2 (p ≤ 0.05) and the lowest caspase 3/7 activity after singular irradiation (p ≤ 0.05). Contrarily, irradiation led to 1.2-fold induction of PON2 in PCI-13 with no effect on SCC-4 (≤0.05), suggesting that PON2 levels reflect the cells' irradiation sensitivity. In agreement, PON2 knockdown resulted in significant higher apoptosis rates (p ≤ 0.05). CONCLUSION: Our findings give first evidence that upregulation of PON2 may protect OSCC against irradiation-induced apoptosis.

The impact of GSTM1/GSTT1 polymorphism for the risk of oral cancer.

OBJECTIVES: Since development of oral squamous cell cancer (OSCC) is triggered by various noxa, different variants of the antioxidant glutathione S-transferases (GSTs) can counteract toxic compounds (e.g., tobacco smoke). Because different polymorphisms of GST are known to have an increased sensitivity to carcinogenic agents, the aim of this study was to analyze whether GSTM1 or GSTT1 polymorphisms increase the risk for the development of OSCC. MATERIALS AND METHODS: GSTM1 and GSTT1 polymorphism was examined in healthy volunteers (n = 93) and in patients with OSCC (n = 100) by PCR after brush biopsy of oral mucosa. Odds ratio (OR) was calculated to evaluate the risk of oral cancer development. RESULTS: GSTM1 and GSTT1 deletion was found in 57% (53/93) and 18% (17/93), respectively, in healthy patients, while the OSCC group showed 57% (57/100) for GSTM1 deletion and 22% (22/100) with a deletion of GSTT1. Odds ratio for GSTM1 polymorphism was 1.00 and for GSTT1 1.26. Comparing smokers and nonsmokers with GSTM1 deletion polymorphism, OR was 4.35, while smokers without GSTM1 deletion showed an OR of 1.45. Adapting these data to the smoking habits of the general population in Germany, the OR was 9.25 for smokers with a GSTM1 deletion and OR 6.68 for smokers without a GSTM1 deletion. In smokers with GSTT1 deletion polymorphism, OR was 1.6 (adapted to the smoking habits of the general population: OR 6.16) and 3.16 (OR 8.56) in smokers without deletion in GSTT1 gene. CONCLUSIONS: Analysis of GST-M1 polymorphism in smokers could help to identify patients with a higher risk for the development of oral cancer. CLINICAL RELEVANCE: Early detection of OSCC due to a close meshed monitoring program for patients with GST-M1 polymorphism could help to improve the patient outcome. For polymorphism investigations, the oral brush biopsy is a sufficient method to gain DNA material.

Effects of a low-level diode laser on oral keratinocytes, oral fibroblasts, endothelial cells and osteoblasts incubated with bisphosphonates: An in vitro study.

Bisphosphonate-associated osteonecrosis of the jaw may have multiple causes, including altered bone remodeling, angiogenesis inhibition and impact of bisphosphonate on the soft tissues. Successful treatment is difficult. As a positive effect of low-level laser application on wound healing is well known, an in vitro study was designed to analyze the effect of low-level laser (280 mW, 670 nm) treatment on keratinocytes, fibroblasts, endothelial cells and osteoblasts treated with clodronate, ibandronate, pamidronate or zoledronate. Pure irradiation had a positive effect on cell viability, whereas bisphosphonate treatment had a negative impact. Viability was significantly increased in cells treated with bisphosphonates and sequel irradiation. There was no effect when the bisphosphonate medium was irradiated. The revealed effect of laser stimulation on cell viability is not due to an inactivation of the bisphosphonates. These results may support the idea of low-level laser therapy as a supportive therapy in patients receiving bisphosphonates to prevent and treat bisphosphonate-associated osteonecrosis of the jaw.

In vitro effects of bisphosphonates on chemotaxis, phagocytosis, and oxidative burst of neutrophil granulocytes.

OBJECTIVES: Bisphosphonate-associated osteonecrosis of the jaws is a serious side effect that mainly occurs in patients receiving highly potent, nitrogen-containing bisphosphonates. Usually the diagnosis is made due to exposed bone and a nonhealing wound. Neutrophil granulocytes are essential for sufficient wound healing; therefore, the influence of different bisphosphonates on neutrophil granulocytes was the focus of this study. MATERIAL AND METHODS: The effect of nitrogen-containing bisphosphonates (ibandronate, pamidronate, and zoledronate) and one non-nitrogen-containing bisphosphonate (clodronate) on chemotaxis, phagocytosis, and oxidative burst of neutrophil granulocytes in human whole blood was analyzed using standard cytometric flow assays. RESULTS: Chemotaxis of neutrophils was reduced by almost 50 % when cells were treated with ibandronate and zoledronate. All tested nitrogen-containing bisphosphonates moderately increased the percentage of phagocytizing neutrophils, whereas the percentage of oxidizing cells was extremely affected. Zoledronate increased the oxidative burst activity even at low concentrations. Treatment with ibandronate and pamidronate reached the same level, but only in at least 10 times the higher concentrations. The maximal burst activity of a single cell reached nearly 150 % compared to control. In this case, zoledronate also caused maximal effects even at low concentrations. Clodronate did not show any effects. CONCLUSION: The results show a proinflammatory effect of the nitrogen-containing effect on neutrophil granulocytes which might contribute to the development of osteonecrosis. CLINICAL RELEVANCE: The altered neutrophil defense might play a key role in the pathogenesis of bisphosphonate-associated osteonecrosis of the jaws, although the underlying causation between inflammatory reaction and the development of necrosis is yet unknown.

Retentive strength of monolithic all-ceramic crowns on implant abutments.

The aim of the study was to determine the retentive strength of monolithic all-ceramic crowns cemented on titanium implant abutments. 225 crowns (75 crowns each of Mark II, Empress CAD, and e.max CAD) were milled using a CAD/ CAM system. The crowns were cemented onto sandblasted titanium implant abutments using five luting agents (Multilink Implant, Variolink II, RelyX Unicem, Fujicem, and Panavia 2.0). After thermocycling, the crowns were removed using a universal testing machine. The location of luting agent residue on the abutment and inner crown surfaces was evaluated. Statistical analysis was performed using ANOVA with the Bonferroni correction. In comparing the luting agents, no significant difference was found between Vita Mark II and Empress CAD. For e.max CAD, the luting agent RelyX Unicem had a significantly higher mean retentive strength than did Multilink Implant (p = 0.003) or Panavia 2.0 (p = 0.001). In comparing the ceramic materials, e.max CAD showed significantly higher pull-off strengths than the other two ceramic materials when the luting agents RelyX Unicem and Fujicem were used (all p < 0.001). The residues of nearly all luting agents were located entirely or almost entirely (75%-100%) on the inner crown surfaces of all ceramic materials, except for the luting agent GC Fujicem, which left more luting agent residue (0%-75%) on the abutment surfaces of all ceramic materials. In comparing the five luting agents, significant differences in the resulting retentive strength were only found for the ceramic material e.max CAD. The other ceramic materials did not show significant differences in retentive strength, independent of the luting agent.

Imaging angiogenesis: perspectives and opportunities in tumour research - a method display.

The growth of solid tumours necessitates angiogenesis. The aim of this paper is the presentation and evaluation of different ex vivo methods for analysing tumour angiogenesis. Oral squamous cell carcinomas (SCC) were induced in mice by subcutaneous injection of tumour cells in the groin region and processed for histology and microvascular corrosion casting. Vascularization was analysed light microscopically using CD31 immunochemistry. Corrosion casts were analysed by scanning electron microscopy (SEM), micro computed tomography (µCT) and synchrotron radiation-based micro computed tomography (SRµCT). Immunochemistry allows for a simple and authentic detection and stereological quantification of the SCC vascularization. µCT imaging of the corrosion casts gives a high-quality overview over the three-dimensional (3D) microvascular architecture. SEM and SRµCT allow a high-definition display of the vessel morphology, providing magnificent detail recognition down to the capillary level enabling imaging of different forms of tumour angiogenesis, e.g., sprouting and intussusceptive angiogenesis. Immunochemistry and SEM are regarded as suitable for most of the morphometrical and morphological assessments because of the simple procedure and the high explanatory power, especially in combination with each other. High resolution SRµCT helps answering specialized questions, however, requires sophisticated data processing for visualization and is of limited availability.