Corrosion behavior of dental implants immersed into human saliva: preliminary results of an in vitro study.

OBJECTIVE: Over the years, different implant surfaces have been used to try to maximize bone to implant contact. The aim of this study was to compare levels of metallic ions and particles dissolution collected from two different dental implants surfaces immersed into human saliva. PATIENTS AND METHODS: A total of 60 dental implants were tested. Group A: sanded with aluminium oxide medium grade particles and acid-etched; Group B: micro-sanded with calcium phosphate powders and acid-etched. Forty implants were immersed in 20 ml of human saliva, twenty, as a control, in sterile saline solution. ICP-MS was performed to detect any metallic ions released from dental implants at T0, on day 1 (T1), on day 3 (T2), after one week (T3), on day 14 (T4), after 3 months (T5) and after 6 months (T6). RESULTS: Dissolution of metallic particles of titanium and nickel, absent in human saliva (T0), were found after one week (T3) for Group B and after 3 months (T5) for Group A. Vanadium was already detected in small concentrations in either group after 1 day, with an exponential growth for Group B. CONCLUSIONS: Preliminary results reported significant values of Ti, Ni and V released by Group B, showing for the first time statistically significant values of vanadium.

Monolithic zirconia and digital impression: case report.

AIMS: The aim of this study is to present a clinical case of a full arch prosthetic rehabilitation on natural teeth, combining both digital work-flow and monolithic zirconia. PATIENTS AND METHODS: Digital impression was taken with an intraoral optical scanner (CS3500, Carestream Dental, Atlanta, GA, USA). A prosthetic rehabilitation was realized on natural teeth using monolithic zirconia from 1.6 to 1.4 and from 2.7 to 2.4 frameworks, while in the aesthetic area (from 2.3 to 1.3), technicians left on the structure a 0.8 mm vestibular space for ceramic layering. DISCUSSION: The combination of digital impression technology and the use of the monolithic zirconia had demonstrated the delivery of the final prosthetic device in a quick time without the need to remodel functional or aesthetic areas. The digital work-flow combines intraoral optical impression techniques and CAD/CAM technology, in order to achieve a fully digital and successful way to deliver prosthetic restorations to patients, providing aesthetics and function in shorter intervals of time. The clinical outcome of this study was satisfactory but a long-term evaluation is needed.

A randomized clinical trial about presence of pathogenic microflora and risk of peri-implantitis: comparison of two different types of implant-abutment connections.

OBJECTIVE: The aim of this in vivo study was to evaluate two different types of implant-abutment connections: screwed connection and cemented connection, analyzing peri-implant bacteria microflora as well as other clinical parameters. PATIENTS AND METHODS: Twenty implants were selected, inserted in 20 patients, 10 with a screwed implant-abutment connection (Group 1) and 10 with a cemented implant-abutment connection (Group 2). The peri-implant microflora was collected, after at least 360 days from the prosthetic rehabilitation, using paper points inserted in peri-implant sulcus for 30 s. Polymerase chain reaction (PCR) Real-time analyzed the presence of 9 bacteria periodontal-pathogens and Candida albicans. RESULTS: Our findings showed that bacteria colonized all Groups analyzed, the average bacterial count was 3.7 E +08 (±1.19) in Group 1, compared to 2.1 E +08 (±0.16) in Group 2; no statistically significant differences were observed (p>0.0.5). In Group 1, however, bacterial colonization of peri-implant sulci was over the pathogenic threshold for 5 bacteria, indicating a high-risk of peri-implantitis. Also in Group 2, results showed a microflora composed by all bacteria analyzed but, in this case, bacterial colonization of peri-implant sulci was over the pathogenic threshold for only 1 bacterium, indicating a lower risk of peri-implantitis. Moreover, clinical parameters (PPD > 3 mm and m SBI > 0) confirmed a greater risk of peri-implantitis in Group 1 compared to Group 2 (p<0.05). CONCLUSIONS: We concluded that, also after only 360 days, implants with screwed connection showed a higher risk of peri-implantitis that implants with cemented connection.

Implant survival and success rates in patients with risk factors: results from a long-term retrospective study with a 10 to 18 years follow-up.

OBJECTIVE: Risk factors for implant therapy are represented by all general and local conditions that through various mechanisms can increase either short-term and long-term failure risk. The aim of this study is to assess the implant survival and implant success rates with single and multiple risk factors. PATIENTS AND METHODS: To address the research purpose, a retrospective cohort study was designed and implemented, including a sample of 225 patients with a total of 871 implants placed. The following risk factors were considered: smoking, bruxism, bone augmentation procedures and the presence of load risk (implants with crown/implant relation > 0.8; angulation > 25°; presence of cantilever). Follow-up ranged from 10 years to 18 years (average follow-up 13.6 years). Failures were subdivided into short-term failures, before the prosthetic phase, and long-term failures, after definitive prosthesis. The success criteria published by Albrektsson and Zarb were adopted. A Cox proportional hazard regression model was used to calculate hazard ratio, with a statistically significant p-value <0.05. RESULTS: Out of the 871 implants placed, 138 did not meet the success criteria, (success rate 84.16%), sixty (43.47%) were classified as "early failure" and seventy-eight as "late failure" (56.53%). A total of 70 dental implants were removed, with a survival rate of 91.96%. CONCLUSIONS: The presence of a single risk factor does not imply a marked increase of failure risk. Among the analyzed factors, the one that proved to be the most dangerous was bruxism, even when presented as the only risk factor. Bruxism with load risk proved to be the most dangerous association (success rate 69.23%) and could be included among the absolute contraindications for implant treatment.

Salivary bacterial leakage into implant-abutment connections: preliminary results of an in vitro study.

OBJECTIVE: The occurrence of bacterial leakage in the internal surface of implants, through implant-abutment interface (IAI), is one of the parameters for analyzing the fabrication quality of the connections. The aim of this in vitro study is to evaluate two different types of implant-abutment connections: the screwed connection (Group 1) and the cemented connection (Group 2), analyzing the permeability of the IAI to bacterial colonization, using human saliva as culture medium. PATIENTS AND METHODS: A total of twelve implants were tested, six in each experimental group. Five healthy patients were enrolled in this study. Two milliliters of non-stimulated saliva were collected from each subject and mixed in a test tube. After 14 days of incubation of the bacteria sample in the implant fixtures, a PCR-Real Time analysis was performed. Fisher's exact test was used to compare the proportions of implant-abutment assembled structures detected with bacterial leakage. Differences in the bacterial counts of the two groups were compared using the Mann-Whitney U test. A p value < 0.05 was considered significant. RESULTS: The results showed a decreased stability with the screwed implant-abutment connections compared to the cemented implant-abutment connections. A mean total bacterial count of 1.2E+07 (± 0.25E+07) for Group 1 and of 7.2E+04 (± 14.4E+04) for Group 2 was found, with a high level of significance, p = .0001. CONCLUSIONS: Within the limitations of this study it can be concluded that bacterial species from human saliva may penetrate along the implant-abutment interface in both connections, however the cemented connection implants showed the lowest amount of bacterial colonization.

Evaluación de la patogenicidad en ratas del Paecilomyces lilacinus LPL-01 utilizando vías diferentes de exposición / Pathogenicity evaluation of Paecilomyces lilacinus to rats

Los nemátodos parásitos de las plantas, conocidos como plagas agrícolas desde el siglo XIX, causan un 9% de pérdidas de cultivos en los países desarrollados y un 14% en los países en desarrollo. El Paecilomyces lilacinus es un hongo parásito que ataca formas sedentarias de los nemátodos, como los huevos. Su valoración como agente microbiano de control debe incluir una evaluación de su virulencia hacia organismos no-diana, tomando en consideración las vías posibles de exposición de los humanos. Para evaluar la patogenicidad de la cepa LPL-01 del P. lilacinus en ratas, se administró por las vías oral, pulmonar e intravenosa. Las observaciones clínicas fueron diarias, y se evaluó el comportamiento del peso corporal. Se estimó el aclaramiento mediante recolección de las heces fecales y análisis de muestras de los pulmones y de la sangre, según la vía de administración, y se evaluó la infectividad mediante toma de muestras de órganos de animales inoculados sacrificados a intervalos. Durante estos sacrificios, y al final de los ensayos, se realizó la necropsia de los animales. No ocurrieron mortalidades, ni evidencias de patogenicidad relacionada con el tratamiento en los ensayos oral y pulmonar, no provocando el hongo una infestación significativa. Por vía endovenosa, el microorganismo provocó alteraciones anátomo-patológicas en hígado y bazo, coincidiendo con el período de máxima infestación. Se concluyó que la cepa LPL-01 del P. lilacinus, a las dosis evaluadas, no es patogénica por las vías oral y pulmonar, siendo levemente patogénica por vía endovenosa

Plant parasitic nematodes have been recognized as agricultural pests in Europe as early as the late 19th century. It has been estimated that plant parasitic nematodes cause crop yield losses of nearly 9% in the developed world, and over 14% in developing countries. The Paecilomyces lilacinus is a parasitic fungi attacking sedentary stages of nematodes, e.g. eggs. Evaluation of this fungus as a microbial control agent, must include an evaluation of its virulence towards non-target organisms, especially vertebrates, with consideration given to potential human exposure scenarios. With the aim of assessing the pathogenicity in rats of the strain LPL-01 of Paecilomyces lilacinus, this fungus was given using several routes of exposure (oral, pulmonary and intravenous route). In all of the assays, clinical examinations were performed daily after administration, and body weight gain of animals was evaluated. Clearance was estimated by means of collection of feces and examination of lungs and blood, depending on the route used, and ineffectiveness was evaluated by enumerating microorganisms from organs and corporal fluids in animals sacrifice at intervals. A gross necropsy of all animals was performed at interim or final sacrifice. There were no mortalities, and no evidence of pathogenicity or treatment-related toxicity either in oral or pulmonary toxicity/pathogenicity tests, without significant infection of test animals. In the intravenous toxicity/pathogenicity test, P. lilacinus caused anatomopathological changes in liver and spleen at the same period when higher infectivity was achieved. It was concluded that P. lilacinus is not pathogenic by oral and pulmonary route, but has some pathogenic effects when intravenous injection is performed

Failure of exogenous LH to prevent PGF2alpha-induced luteolysis in beef cows.

Henderson and McNatty (Prostaglandins 9:779, 1975) proposed that LH from the preovulatory LH surge attached to receptors on luteal cells and that this attachment might protect the early corpus luteum from PGF2alpha induced luteolysis. To test this hypothesis, experiments were performed on heifers at day 10-12 of the cycle. Both jugular veins were catheterized and infusions of either saline (0.64 ml/min) or LH-NIH-B9 (10 microgram/min; 0.64 ml/min) were given. Saline infusions were from 0-12 h; LH infusions were for 10 h and were preceded by a 2 h saline infusion. All animals were given 25 mg PGF2alpha im at 6 h (6 h into the saline infusion and 4 h into the LH infusion). Blood samples were taken at 0.5 h, 1 h and 4 h intervals from 0-12h, 13-18 h and 12-42 h respectively. Serum was assayed for LH and progesterone by radioimmunoassay methods. Two animals received saline and two received LH in each experiment. Each treatment was replicated 6 times. LH infusion resulted in a mean serum LH of 75 ng/ml compared to 0.90 ng/ml in saline infused animals. This elevation of LH did not alter PGF2alpha induced luteolysis as indicated by decline in serum progesterone. This experiment does not support the hypothesis that the newly formed corpus luteum is resistant to PGF2alpha because of protection afforded by the proestrus LH surge.