In vitro assessment of internal implant-abutment connections with different cone angles under static loading using synchrotron-based radiation.

BACKGROUND: The stability of implant-abutment connection is crucial to minimize mechanical and biological complications. Therefore, an assessment of the microgap behavior and abutment displacement in different implant-abutment designs was performed. METHODS: Four implant systems were tested, three with a conical implant-abutment connection based on friction fit and a cone angle < 12 ° (Medentika, Medentis, NobelActive) and a system with an angulated connection (< 40°) (Semados). In different static loading conditions (30 N - 90º, 100 N - 90º, 200 N - 30º) the microgap and abutment displacement was evaluated using synchrotron-based microtomography and phase-contrast radioscopy with numerical forward simulation of the optical Fresnel propagation yielding an accuracy down to 0.1 µm. RESULTS: Microgaps were present in all implant systems prior to loading (0.15-9 µm). Values increased with mounting force and angle up to 40.5 µm at an off axis loading of 100 N in a 90° angle. CONCLUSIONS: In contrast to the implant-abutment connection with a large cone angle (45°), the conical connections based on a friction fit (small cone angles with < 12°) demonstrated an abutment displacement which resulted in a deformation of the outer implant wall. The design of the implant-abutment connection seems to be crucial for the force distribution on the implant wall which might influence peri-implant bone stability.

Horizontal bone grafting using equine-derived cancellous bone blocks is associated with severe complications: A prospective clinical and histological pilot study.

AIMS: The aim of this prospective, clinical study was to evaluate the clinical performance and histological outcome of a new equine hydroxyapatite collagenated bone block (eHAC) for horizontal bone grafting prior to implant placement. MATERIALS AND METHODS: Five patients (two male/three female) with a mean age of 51.6 years (range 22-66 years) and a reduced horizontal bone width of the alveolar ridge (mean 3.5 mm) underwent horizontal bone grafting using eHAC at 10 grafting sites. Reentry was performed 6.9 months after the horizontal grafting procedure. Clinical follow-up (mean 28.9 month) considered width gain of the alveolar ridge, soft tissue healing, and complications. To evaluate graft incorporation, four additional patients underwent histological assessment of equine blocks adjacent to autologous blocks 3 and 6 months after grafting. RESULTS: The study was terminated after graft failure was observed in four of five patients. Mean horizontal bone width had increased by 3.6 ± 1.22 mm. Three out of nine implants placed had to be removed due to graft failure. Histological evaluation revealed large amounts of soft connective tissue within the grafts (mean 67.3 ± 9.5%). The proportion of new bone formation 3 months after the lateral grafting procedure revealed an average of 8.6%, compared to 11.4% after 6 to 7 months. CONCLUSION: Lateral ridge grafting using eHAC achieved measurable horizontal width gain but revealed high rates of severe complications. CLINICAL IMPLICATIONS: Within the limitations of this study, eHAC bone blocks cannot be recommended for horizontal bone grafting.

The influence of storage temperature on fracture behavior of cryopreserved teeth-An in vitro study.

OBJECTIVES: Cryopreservation is discussed as a viable method of preserving teeth for determined autogenous tooth transplantation. Unchanged physical properties of hard tooth tissues are crucial for functional healing. Due to different thermal expansion coefficients of enamel and dentin or the crystallization process, the freezing process may lead to crack formation, which could adversely impact the long-term prognosis of the teeth. MATERIAL AND METHODS: Twenty third molars (n = 20) were frozen slowly using a conservative cryopreservation protocol and stored at -80°C (group 1) and -196°C (group 2). After a storage time of 2 weeks, the samples were thawed to a temperature of +36°C and embedded in polymethyl methacrylate blocks. Cyclic loading was carried out using a spherical steel test specimen with 50,000 mechanical load cycles, followed by load to failure testing for determination of critical load. RESULTS: No significant difference in the first load drop could be detected during the load to failure test under different storage conditions. The values until fracture correlated very closely in contralateral tooth pairs, which emphasizes the importance of crown geometry in load to failure tests. CONCLUSIONS: Conclusions: Cryopreservation, specifically the storage temperature, does not appear to have a significant effect on the physical properties of tooth transplants.

WITHDRAWN: Synchrotron-based Radiography of Conical- vs. Butt-joint Implant Abutment Connections.

Ahead of Print article withdrawn by publisher.

Premolar autotransplantation in juvenile dentition: quantitative assessment of vertical bone and soft tissue growth.

OBJECTIVE: Premolar autotransplantation represents an effective therapeutic option for the treatment of juvenile dentition with either aquired or congenital hypodontia. The objective of this prospective clinical study was to quantitatively assess bone and soft tissue levels after autogenous premolar transplantation by clinical and radiographic parameters. STUDY DESIGN: In the study, 26 premolars were transplanted in 20 patients after traumatic tooth loss (n = 16) or congenital aplasia (n = 10) in the anterior maxilla. Based on standardized photographic documentation, the relative soft tissue level was measured compared to the healthy adjacent teeth. Radiographic findings included evaluation of root resorption, pulp canal obliteration, and relative bone height. RESULTS: Average survival rate of transplanted premolars (n = 26) was 100% over a follow-up period of 29 months (range 10-60 months). The relative soft tissue level significantly increased by +1.1 mm (P < .01). Radiographs showed a tendency toward vertical bone growth. Continuous root development and signs of pulpal healing were observed postoperatively in 18 transplants (69.2%). CONCLUSIONS: Autogenous premolar transplantation represents a safe method to ensure functional and aesthetic rehabilitation in the anterior maxilla irrespective of the nature of tooth loss.

Laser therapy of a dermal nevus in the esthetic zone of the nasal tip: A case report and comprehensive literature review.

This case report demonstrates the ablation of a dermal nevus using a diode laser in the esthetically very demanding facial area of the nasal tip. The clinical outcome shows good results and a high level of patient satisfaction. Due to effective wound granulation and healing, elaborate skin grafts could be avoided. The application of the contact laser ensures safe treatment in highly perfused areas thanks to haptic feedback and good coagulative effect. The method should therefore be considered as an alternative to other ablative procedures for benign lesions in the facial area.

Influence of intraaortic balloon pump counterpulsation on transesophageal echocardiography derived determinants of diastolic function.

INTRODUCTION: Intraaortic balloon pump counterpulsation (IABP) is often used in patients with acute coronary syndrome for its favourable effects on left ventricular (LV) systolic function and coronary perfusion. However, the effects of IABP on LV diastolic function have not been comprehensively investigated. Acute diastolic dysfunction has been linked to increased morbidity and mortality. The aim of this study was to examine the influence of IABP on LV diastolic dysfunction using standard TEE derived parameters. METHODS: Intraoperative TEE was performed in 10 patients (mean age 65 ± 11 yrs) undergoing urgent coronary artery bypass graft surgery (CABG), who had received an IABP preoperatively. TEE derived measures of diastolic dysfunction included early to late transmitral Doppler inflow velocity ratio (E/A), deceleration time (Dt), pulmonary venous systolic to diastolic Doppler velocity ratio (S/D), transmitral propagation velocity (Vp), and the ratio of early to late mitral annular tissue Doppler velocities (e'/a'). Statistical analyses included the Wilcoxon Sign-Rank test, and a p<0.05 was considered significant. RESULTS: Transmitral inflow E/A ratios increased significantly from 0.86 to 1.07 (p < 0.05), while Dt decreased significantly from 218 to 180 ms (p < 0.05) with the use of IABP. Significant increases in Vp (34 cm/s to 43 cm/s; p < 0.05), and e'/a' (0.58 to 0.71; p < 0.05) suggested a favourable influence of intraaortic counterpulsation on diastolic function. CONCLUSION: The use of perioperative IABP significantly improves TEE derived parameters of diastolic function consistent with a favourable impact on LV relaxation in cardiac surgery patients undergoing CABG.

Primary canine auto-transplantation: a new surgical technique.

OBJECTIVE: The aim of this study was to investigate whether the growth of soft tissue and bone in children with traumatic tooth loss or agenesis of teeth can be developed reliably, using a new technique of autogenous primary canine transplant. STUDY DESIGN: A total of 10 patients (age range, 7-13 years) were treated either for trauma or for agenesis (n = 14 primary canine transplants). In addition to the clinical examination, patients were subjected to radiologic examinations with regard to root resorption, bone height, and soft tissue level. RESULTS: With an average survival rate of 87%, the average survival time of the transplants using the Kaplan-Meier estimator was 5.2 years. In all cases, soft tissue and bone growth was effectively developed. CONCLUSIONS: Autogenous primary canine transplant is a reliable surgical method for rehabilitating children in the early mixed dentition after traumatic tooth loss, enabling adequate soft tissue and bone growth.

Vascular endothelial growth factor expression in nasal polyps of aspirin-intolerant patients.

OBJECTIVE: To study differences between aspirin-tolerant patients and aspirin-intolerant patients concerning vascular endothelial growth factor (VEGF) expression. Recent publications strongly suggest the involvement of VEGF and its receptors in the pathophysiologic process of nasal polyps. DESIGN: We subjected 43 polyp specimens to semiquantitative immunohistochemical analysis. We quantified VEGF and its receptors (Flk, Flt, and neuropilin) in all samples. To gain insight into potential VEGF-mediated cellular responses, we determined proliferative (Ki67) and apoptotic (caspase 3) indices. PATIENTS: Polyp samples were obtained from 22 aspirin-intolerant patients and from 21 aspirin-tolerant patients, and control specimens were obtained from 24 subjects with healthy nasal respiratory mucosa. SETTING: Laboratory; Department of Otorhinolaryngology-Head and Neck Surgery, University Medical Center of the Johannes Gutenberg University Mainz, Mainz, Germany. MAIN OUTCOME MEASURES: Expression levels of VEGF, VEGF receptors. and proliferative and apoptotic indices. RESULTS: We found higher expressed levels of VEGF and neuropilin and stronger proliferation in nasal polyps from aspirin-tolerant and aspirin-intolerant patients compared with controls. In polyps from aspirin-intolerant patients, VEGF was expressed at considerably higher levels compared with those from aspirin-tolerant subjects. Apoptotic activity remained unchanged in all 3 groups. CONCLUSIONS: Nasal polyps from aspirin-tolerant and aspirin-intolerant patients are characterized by strong proliferation and high levels of VEGF and neuropilin expression. Nasal polyps from aspirin-intolerant patients show distinctly increased VEGF levels. The relevance of these findings for future therapeutic approaches is yet to be determined.