Effects of screw channel angulation on the fracture resistance of one-piece zirconia crown with titanium base.

PURPOSE: The design of the angulated screw channel in implant restorations allows the possibility to correct angulation discrepancies, especially in the anterior maxilla. However, the effects of varied screw channel angulations on fracture resistances and fracture patterns of the implant restorations are still uncertain, and thus the aim of this study. MATERIALS AND METHODS: Angulated screw channel monolithic zirconia crowns (Nobel Biocare) with three different angulation groups-straight (ASC1), 15° (ASC15), and 25° (ASC25)-were digitally designed from a left central incisor prototype scan. Following fabrication, 10 samples of each group were individually mounted onto implant replicas embedded in standardized type V stone gypsum cylinder jigs (25 mm × 25 mm). All screws were manually torqued to 35 Ncm according to the manufacturer's recommendation, and screw access openings were subsequently sealed with resin composite. To mimic the off-axis loading of the central incisor, the specimens were then loaded at a cephalometric interincisal relationship of 135° between the long axis of the crown and the Instron force applicator, with crosshead speed set at 0.5 mm/min. Fractured abutment surfaces were examined, and selected specimens were further evaluated by scanning electron microscopy. Screw torque values were also measured after the catastrophic loading. One-way ANOVA was used to compare load-to-fracture values between groups, with the statistical significance set at 0.05 (p values). RESULTS: The mean load-to-fracture values in descending order were 331.24N (±34.00N) in ASC15, 325.22N (±35.50N) in ASC25, and 302.04N (±45.10N) in ASC1, with no statistically significant differences between groups. Considerable screw torque losses were found in all groups after catastrophically loading. The average torque loss was 84% in ASC1, 86% in ASC15, and 94% in ASC25. 16 out of 30 specimens experienced screw loosening; one ASC1 screw underwent slight deformation. Crowns of all tested groups exhibited cohesive fracture patterns at the screw-metallic-zirconia interfaces. CONCLUSIONS: Within the limitations of this in vitro study, one-piece monolithic zirconia implant crowns with varied screw channel angulations shared similar fracture-strength and fracture-mode characteristics. The zirconia-titanium base junctions exhibited the weakest link of all restorations.

The role of the adaptive immune system in burn-induced heterotopic ossification and mesenchymal cell osteogenic differentiation.

BACKGROUND: Heterotopic ossification (HO) is the pathologic process of extraskeletal bone formation. Although the exact etiology remains unknown, inflammation appears to catalyze disease progression. The goal of this study is to determine the impact of the adaptive immune system on HO. METHODS: HO was induced in 8-wk-old control C57BL/6 and immunocompromised Rag1tm1Mom (Rag1 KO) male mice deficient in B- and T-lymphocytes via combined Achilles tenotomy and burn injury. Microcomputed tomography quantified the extent of HO formation at the tenotomy site. Adipose-derived mesenchymal stem cells were harvested to evaluate osteogenic differentiation potential. RESULTS: Areas of developing HO demonstrated substantial enrichment of CD45 + leukocytes at 3 wk after injury. HO from Rag1 KO mice was substantially less mature with foci of cartilage and disorganized trabecular bone present 12 wk after injury. Rag1 KO mice formed 60% less bone compared to immunocompetent controls (4.67 ± 1.5 mm versus 7.76 ± 0.65 mm; P = 0.001). Tartrate-resistant acid phosphatase staining and immunofluorescent analysis of osteoprotegerin and nuclear factor kappa-light-chain-enhancer of activated B cells demonstrated no appreciable difference in osteoclast number or activation. Alizarin red staining in vitro demonstrated a significant decrease in osteogenic potential in immunocompromised mice compared to controls (29.1 ± 0.54 mm versus 12.1 ± 0.14 mm; P < 0.001). CONCLUSIONS: We demonstrate a prominent role for the adaptive immune system in the development of HO. In the absence of mature B- and T-lymphocytes, HO growth and development are attenuated. Furthermore, we demonstrate that mesenchymal populations from B- and T-cell deficient mice are inherently less osteogenic. This study identifies a potential therapeutic role for modulation of the adaptive immune system in the treatment of HO.

Evaluation of Salivary Cytokines for Diagnosis of both Trauma-Induced and Genetic Heterotopic Ossification.

PURPOSE: Heterotopic ossification (HO) occurs in the setting of persistent systemic inflammation. The identification of reliable biomarkers can serve as an early diagnostic tool for HO, especially given the current lack of effective treatment strategies. Although serum biomarkers have great utility, they can be inappropriate or ineffective in traumatic acute injuries and in patients with fibrodysplasia ossificans progressiva (FOP). Therefore, the goal of this study is to profile the cytokines associated with HO using a different non-invasive source of biomarkers. METHODS: Serum and saliva were collected from a model of trauma-induced HO (tHO) with hind limb Achilles' tenotomy and dorsal burn injury at indicated time points (pre-injury, 48 h, 1 week, and 3 weeks post-injury) and a genetic non-trauma HO model (Nfatc1-Cre/caAcvr1fl/wt ). Samples were analyzed for 27 cytokines using the Bio-Plex assay. Histologic evaluation was performed in Nfatc1-Cre/caAcvr1fl/wt mice and at 48 h and 1 week post-injury in burn tenotomy mice. The mRNA expression levels of these cytokines at the tenotomy site were also quantified with quantitative real-time PCR. Pearson correlation coefficient was assessed between saliva and serum. RESULTS: Levels of TNF-α and IL-1ß peaked at 48 h and 1 week post-injury in the burn/tenotomy cohort, and these values were significantly higher when compared with both uninjured (p < 0.01, p < 0.03) and burn-only mice (p < 0.01, p < 0.01). Immunofluorescence staining confirmed enhanced expression of IL-1ß, TNF-α, and MCP-1 at the tenotomy site 48 h after injury. Monocyte chemoattractant protein-1 (MCP-1) and VEGF was detected in saliva showing elevated levels at 1 week post-injury in our tHO model when compared with both uninjured (p < 0.001, p < 0.01) and burn-only mice (p < 0.005, p < 0.01). The Pearson correlation between serum MCP-1 and salivary MCP-1 was statistically significant (r = 0.9686, p < 0.001) Similarly, the Pearson correlation between serum VEGF and salivary VEGF was statistically significant (r = 0.9709, p < 0.05). CONCLUSION: In this preliminary study, we characterized the diagnostic potential of specific salivary cytokines that may serve as biomarkers for an early-stage diagnosis of HO. This study identified two candidate biomarkers for further study and suggests a novel method for diagnosis in the context of current difficult diagnosis and risks of current diagnostic methods in certain patients.

Patrones Epidemiológicos del Trauma Dentoalveolar (PatologíaGES) en Pacientes Adultos Atendidos en un Centro de Trauma de Chile Durante 2 Períodos / Epidemiological Patterns of Traumatic Dental Injuries (GES Disease) in Adult Patients Treated at a Chilean National Trauma Center during 2 Periods

El trauma dentoalveolar (TDA) constituye un conjunto de lesiones que comprometen los dientes o a sus estructuras periodontales. En Chile, desde el año 2007, la primera consulta/tratamiento de urgencia del TDA está cubierta por la Ley N 19.966, para todas las personas afiliadas al Fondo Nacional de Salud (FONASA) y a las Instituciones de Salud Previsional Privadas (ISAPRE) a través del Programa de Garantías Explícitas en Salud (GES). Escasos estudios nacionales se han realizado en TDA de adultos y ninguno en relación al impacto del GES en estas lesiones. Se realizó un estudio retrospectivo, descriptivo y transversal de TDA con los Datos de Urgencia de todos los pacientes adultos atendidos en el Hospital de Urgencia Asistencia Pública. Se compararon las variables clínicas, etiológicas, demográficas y sociales entre 2 períodos: pre-GES (1 de Julio de 2005 al 30 de Junio de 2006) y post-GES (1 de julio de 2012 al 31 junio de 2013). En los 2 períodos se observó una mayor frecuencia de TDA en el sexo masculino del grupo de 20­29 años, producidos en la mayoría de los casos por violencia interpersonal. Sin embargo se observó en el período post-GES una mayor consulta de TDA por Accidente vehículo-motorizado, presentándose lesiones de mayor gravedad. A pesar de la implementación del GES, se observó una alta frecuencia de TDA no tratados, esto podría deberse a la gravedad del estado sistémico del paciente (postergando el tratamiento de TDA), a la falta de insumos o a la inequidad en la entrega de recursos a los servicios de salud. Es necesario realizar más estudios y vigilancia de parte de la autoridad sanitaria para mejorar las garantías del GES en el tratamiento de los TDA.

Traumatic dental injury (TDI) is a group of injuries that affect hard dental tissues and/or periodontal structures. Since 2007 the first emergency treatment/consult of TDI, for both the National Health Fund (FONASA) and profit private insurer (ISAPRE) affiliates, is guaranteed in the Regulation of Explicit Health Guarantees (GES) established by Chilean Law 19.966. Few national TDI studies in adults have been carried out, and none in relation to the impact of GES in this type of lesion. A retrospective cross sectional study of emergency charts of all adult patients attended at the Hospital de Urgencia Asistencia Pública. Etiological, clinical, demographic and social variables were compared between 2 time periods, Pre-GES period (July, 1 2005 to June, 30 June 2006) versus Post-GES period (July, 1 2012 to June, 31 2013). A high incidence of TDI caused by interpersonal violence in males between 20 and 29 years old was observed in both periods. However, an increased TDI with more severe injuries caused by automobile accident was observed during the post-GES period. In spite of GES implementation, high frequency of non-treated TDI was seen in the present study, this could be due to the severity of the patient´s systemic condition (delaying the TDI treatment), a lack of resources and/or inequity in the delivery of these healthcare resources. More studies and surveillance programs by the Government are needed to improve TDI treatment guarantees, and as well as regular assessment of GES compliance.