Thermal necrosis-aided dental implant removal: A rabbit model pilot study

Background: The significant advances in the materials and biological aspects of dental implants haven't completely eradicated the implant failures. The removal of osseointegrated but otherwise failed implants present several challenges including adjacent tissues damage and necessity of bone augmentation for reimplantation. Controlled thermal necrosis has emerged as an alternative technique to aid removal of osseointegrated dental implants with minimal to no defect to healthy bone or surrounding tissues. This study aimed to evaluate the thermal necrosis-aided implant removal method in a rabbit osseointegration model. Material and methods: A total of 8 male New Zealand rabbits were used in the study. Two dental implants were placed on each femur of the rabbits. Heating of the implants was performed after 7 weeks following the implantation. Heating was done by contacting the tip of an electrosurgey tool in monopolar mode at different power settings and contact durations (5W - 2 seconds, 5W - 10 seconds, and 10 W - 10 seconds). No heating was done on the control group. Implant stability right after implantation, before heat application and after heat application was determined using an Osstell™ Mentor Device. Following the removal of implants histological analyses were performed to determine the effects of heat application at cellular level. Results: ISQ values of the 10W-10s group was significantly lower compared to the other groups (p<0.001). No indication of progressive necrosis or irreversible damage was observed in any of the groups. However, the percent of empty-apoptotic lacunae were statistically higher in the 5W-10s and the 10W-10s groups compared the control and the 5W-2s groups. Conclusions: Within the conditions of this study, we conclude that heat application with an electrosurgery tool using monopolar mode at 10W power for 10 seconds is optimal for reversing osseointegration with no extensive or progressive damage to the bone. (AU)

Impact of implant thread design on insertion torque and osseointegration: a preclinical model

Background: Successful osseointegration of endosteal dental implants has been attributed to implant design, including the macro-, micro- and nano- geometric properties. Based on current literature pertaining to implant design, the resultant cellular and bone healing response is unknown when the thread thickness of the implants is increased, resulting in an increased contact area in implants designed with healing chambers. The aim of this study was to evaluate the effect of two implant designs with different thread profiles on the osseointegration parameters and implant stability at 3- and 6-weeks in vivo using a well-established preclinical dog model.Material and methods: A total of 48 type V Ti alloy implants were divided in two groups according to their thread design (D1= +0.1x/mm and D2= +0.15x/mm) and placed in an interpolated fashion into the radii of six beagles. Insertion torque was measured at time of placement, radii were extracted for histological processing following 3- and 6-week healing intervals. Histologic and histomorphometric analyses were performed in terms of bone to implant contact (%BIC) and bone area fraction occupancy within implant threads (%BAFO). Statistical analyses were performed through a linear mixed model with fixed factors of time and implant thread design.Results: Surface roughness analysis demonstrated no significant differences in Sa and Sq between D1 and D2 implant designs, which confirmed that both implant designs were homogenous except for their respective thread profiles. For insertion torque, statistically significant lower values were recorded for D1 in comparison to D2 (59.6 ± 11.1 and 78.9 ± 10.1 N⋅cm, respectively). Furthermore, there were no significant differences with respect to histological analysis and histomorphometric parameters, between D1 and D2 at both time points.(AU)

Effects of a local single dose administration of growth hormone on the osseointegration of titanium implants

Background: The aim of the present study was to evaluate the effect of different concentrations of growth hormone (GH) on endosteal implant’s surface at the early stages of osseointegration. Material and Methods: Sixty tapered acid-etched titanium implants were divided into four groups: i) Collagen, used as a control group; and three experimental groups, where after collagen coating, GH was administered directly to the surface in varying concentrations: ii) 0.265 mg, iii) 0.53 mg, and iv) 1 mg. Implants were placed in an interpolated fashion in the anterior flange of C3, C4 or C5 of 15 sheep with minimum distance of 6 mm between implants. After 3-, 6- and 12-weeks of healing samples were harvested, histologically processed, qualitatively and quantitatively assessed for bone-to-implant contact (BIC) and bone area fraction occupancy (BAFO). Results: Statistical analysis as a function of time in vivo and coating resulted in no significant differences for BIC and BAFO at any evaluation time point. Histological evaluation demonstrated similar osseointegration features for all groups with woven bone formation at 3 weeks and progressive replacement of woven for lamellar bone in close contact with the implant surface and within the implant’s threads. Conclusions: A single local application of growth hormone to the surface of titanium implants did not yield improved implant osseointegration independent of healing time.(AU)

Efecto de distintos sistemas de instrumentación con rotación continua o alternante en la conformación y limpieza de los conductos radiculares de raíces mesiales de primeros molares mandibulares / Effect of different rotary and reciprocation instrument systems in the shaping and cleaning of mesial root canals in first mandibular molars

OBJETIVO: Comparar en raíces mesiales de primeros molares mandibulares ex vivo, la acción de distintos sistemas de instrumentación en la conformación y limpieza de los conductos radiculares. Material y MÉTODOS: Se emplearon 25 raíces, cuyos conductos radiculares fueron instrumentados con los sistemas: WaveOne Gold, Reciproc, Mtwo, ProTaper Next y ProTaper Gold. Las raíces fueron seccionadas transversalmente a nivel de los tercios cervi-cal, medio y apical, y las muestras se analizaron con microscopía Confocal. En cada tercio se evaluó: a) Acción de los instrumentos sobre las paredes del conducto radicular, b) Presencia de istmos y su relación con la preparación quirúrgica y c) Medición en micrómetros cuadradas de las zonas no instrumentadas. Para la evaluación estadística se utilizó el análisis de varianza de dos factores con medidas repetidas en el factor tercio. El nivel de significación fue establecido en P < 0,05.RESULTADOS: Todos los sistemas mostraron una preparación regular de la superficie dentinaria excepto el Reciproc R25 que produjo zonas de desgarramiento de dentina. Con todos ellos se generaron fisuras dentinarias, dispuestas perpendiculares, oblicuas o paralelas a la pared del conducto radicular. Los istmos presentaban restos impactados en su interior. En ocasiones, ambos conductos mesiales se encontraban unidos por un istmo determinando a veces un conducto mediomesial. Se observó entre un 19.4% y 42.2% de la superficie de los conductos radiculares no instrumentada, sin diferencias significativas entre grupos ni entre tercios

OBJECTIVE: To compare ex vivo, the action of different systems in cleaning and shaping the mesial root canals of mandibular first molars. Material and METHODS: 25 roots were instrumented with the following systems: WaveOne Gold, Reciproc, Mtwo, ProTaper Next, and ProTaper Gold. The roots were cross-sectioned at the level of the cervical, middle, and apical thirds, and the samples were analyzed with Confocal microscopy. In each third, the following aspects were evaluated: a) Action of the instruments on the walls of the root canal, b) Presence of isthmus and their relationship with the surgical preparation, and c) Measurement in square micrometers of the non-instrumented areas. For the statistical evaluation, the two-factor analysis of varianza with repeated measures in the third factor was used. The level of significance was established at P < 0,05. RESULTS: All systems showed a regular preparation of the dentin surface except Reciproc R25 which produced areas of dentinal tears. With every system, dentin cracks were generated, arranged perpendicular, oblique, or parallel to the wall of the root canal. The isthmus showed the presence of debris packed inside. On occasions, both mesial canals were unified by an isthmus, sometimes conforming a middle mesial canal. Between 19.4% and 42.2% non-instrumented root canal surface was observed, without significant differences between groups or between thirds. CONCLUSIONS: None of the system used completely cleaned and shaped the root canals, leaving a significant porcentage of the dentinal walls non-instrumented

Fracture resistance after implantoplasty in three implant-abutment connection designs

BACKGROUND: To assess the effect of implantoplasty and implant-abutment design on the fracture resistance and macroscopic morphology of narrow-diameter (3.5 mm) dental implants. MATERIAL AND METHODS: SCREW-shaped titanium dental implants (n = 48) were studied in vitro. Three groups (n = 16) were established, based on implant-abutment connection type: external hexagon, internal hexagon and conical. Eight implants from each group were subjected to an implantoplasty procedure; the remaining 8 implants served as controls. Implant wall thickness was recorded. All samples were subjected to a static strength test. RESULTS: The mean wall thickness reductions varied between 106.46 and 153.75 μm. The mean fracture strengths for the control and test groups were, respectively, 1211.90 ± 89.95 N and 873.11 ± 92.37 N in the external hexagon implants; 918.41 ± 97.19 N and 661.29 ± 58.03 N in the internal hexagon implants; and 1058.67 ± 114.05 N and 747.32 ± 90.05 N in the conical connection implants. Implant wall thickness and fracture resistance (P < 0.001) showed a positive correlation. Fracture strength was influenced by both implantoplasty (P < 0.001) and connection type (P < 0.001). CONCLUSIONS: Implantoplasty in diameter-reduced implants decreases implant wall thickness and fracture resistance, and varies depending on the implant-abutment connection. Internal hexagon and conical connection implants seem to be more prone to fracture after implantoplasty

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Measurement of gap between abutment and fixture in dental conical connection implants. A focused ion beam SEM observation

BACKGROUND: The aim of the authors was to examine the abutment-fixture interface in Morse-type conical implants in order to verify gaps at this level using a new microscopical approach. MATERIAL AND METHODS: In this in vitro study, 20 abutment-fixture complexes were prepared by sectioning (longitudinal and cross-sectional to the long axis) with a microtome and then with a focused ion beam (FIB). This is a micrometric machine tool that uses gallium ions to abrade circumscribed areas to dig deeper into the cuts obtained with the microtome in order to eliminate cut-induced artifacts. This is because the FIB abrasion is practically free from artifacts, which are normally generated by the action of the microtome blades or other techniques. Samples were then observed by scanning electron microscopy (SEM). RESULTS: The observation of the abraded parts with the FIB permitted measurement of the real gap between the implant-abutment components. A variable amount of gap was retrieved (from 0 to 3 μm) by the observations, confirming the non-hermetic nature of the connection. It has to be pointed out that in approximately 65% of cases, the gap accounted for less than 1 μm. CONCLUSIONS: The reported data confirmed that the analyzed connection system allowed for minimal gap. However, from the evidence of the present analysis, it cannot be assumed that the 2 parts of a Morse-type conical implant are fused in 1 piece, which would create a perfectly matched hermetic connection

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Effect of different solutions in reversing the damage caused by radiotherapy in dentin structure

BACKGROUND: Previous studies have shown that radiotherapy of the head and neck region can cause direct changes in dental structure. This study evaluated the effect of different solutions on the dentin chemical composition and collagen structure of irradiated dentin. MATERIAL AND METHODS: Sixty maxillary canines were distributed in 2 groups (n = 30): non-irradiated and irradiated (radiotherapy: X-rays of 6 MV in 30 cycles of 2 Gy to 60 Gy). The teeth were sectioned, sanded, and polished to obtain 3x3x2 mm fragments, which were redistributed in 3 subgroups (n = 10) according to the treatment employed: chlorhexidine 2% (CL), chitosan 0.2% (QT), and 0.5 M carbodiimide (EDC). The samples were analyzed in FTIR at time zero (T0-control) and after 1 (T1), 3 (T3), and 5 (T5) minutes of immersion in the tested solutions. The data for the areas of the carbonate (C), amide I (AI) bands, and the ratio between the areas of the amide III/proline and hydroxyproline (AIII/PH) bands were analyzed using ANOVA and Tukey test (alpha = 5%).RESULTS: QT showed lower C values at T1, T3, and T5 (P < 0.0001), presenting lower values when compared to CL and EDC subgroups (P < 0.05). AI values at T3 and T5 were higher than T0-control and T1, independently of the radiotherapy and dentin treatment factors (P < 0.05). At T0-control, the AIII/PH ratio was lower in the irradiated group (P < 0.05), whereas the EDC treatment at T1, T3, and T5 and QT at T3 and T5 increased these values (P < 0.05), making them similar to non-irradiated subgroups (P>0.05). CONCLUSIONS: Radiotherapy changes the secondary structure of collagen, and EDC was able to restore collagen integrity after 1 minute of immersion, without changing dentin inorganic composition

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Assessing osseointegration of metallic implants with boronized surface treatment

BACKGROUND: Modification of endosteal implants through surface treatments have been investigated to improve osseointegration. Boronization has demonstrated favorable mechanical properties, but limited studies have assessed translational, in vivo outcomes. This study investigated the effect of implant surface boronization on bone healing. MATERIAL AND METHODS: Two implant surface roughness profiles (acid etched, machined) in CP titanium (type II) alloy implants were boronized by solid-state diffusion until 10-15 µm boron coating was achieved. The surface-treated implants were placed bilaterally into 5 adult sheep ilia for three and six weeks. Four implant groups were tested: boronized machined (BM), boronized acid-etched (BAA), control machined (CM), and control acid-etched (CAA). Osseointegration was quantified by calculating bone to implant contact (BIC) and bone area fraction occupancy (BAFO). RESULTS: Both implant types treated with boronization had BIC values not statistically different from machined control implants at t=3 weeks, and significantly less than acid-etched control (p < 0.02). BAFO values were not statistically different for all 3-week groups except machined control (significantly less at p < 0.02). BAFO had a significant downward trend from 3 to 6 weeks in both boronized implant types (p < 0.03) while both control implant types had significant increases in BIC and BAFO from 3 to 6 weeks. CONCLUSIONS: Non-decalcified histology depicted intramembranous-like healing/remodeling in bone for controls, but an absence of this dynamic process in bone for boronized implants. These findings are inconsistent with in vitro work describing bone regenerative properties of elemental Boron and suggests that effects of boron on in vivobone healing warrant further investigation

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Candida albicans biofilms on different materials for manufacturing implant abutments and prostheses

BACKGROUND: Morphological, physical and chemical properties of both implants and prostheses can determine the biofilm formation on their surface and increase the risk of biological complications. The aim of this study was to evaluate the capacity of biofilm formation of Candida albicans on different materials used to manufacture abutments and prostheses. MATERIAL AND METHODS: Biofilm formation was analyzed on cp grade II titanium, cobalt-chromium alloy and zirconia, silicone, acrylic resin (polymethylmethacrylate) and nano-hybrid composite. Some samples were partially covered with lithium disilicate glass ceramic to study specifically the junction areas. C. albicans was incubated in a biofilm reactor at 37 °C with agitation. The biofilm formation was evaluated at 24 and 48 hours. In addition, the morphology of the biofilm was evaluated by scanning electron microscopy. RESULTS: C. albicans developed biofilms on the surface of all materials tested. Cobalt-chromium alloy showed the lowest density of adhered biofilm, followed by zirconia and titanium. Silicone and resin showed up to 20 times higher density of biofilm. A higher biofilm formation was observed when junctions of materials presented micro-pores or imperfections. CONCLUSIONS: The biofilm formed in the three materials used in the manufacture of abutments and prostheses showed no major differences, being far less dense than in the resins. Two clinical recommendations can be made: to avoid the presence of resins in the subgingival area of implant prostheses and to design prostheses placing cobalt-chromium alloy/ceramic or titanium/ceramic junctions as far as possible from implants

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Is the re-use of sterilized implant abutments safe enough? (Implant abutment safety)

Background: The reuse of implant healing abutments is common in dental practice. Effective elimination of bacteria and viruses is accomplished by conventional sterilization. The aim of this work was to explore the eventual survival of microorganisms on sterilized healing abutments and to rule out the presence of transmissible organic material after standard procedures. Material and Methods: A total of 55 healing abutments previously used in patients will be washed and sterilized in a steam autoclave at 121ºC for 15 min. Each healing abutment will be cultured in Brain Heart Infusion broth (BHI) under strict aseptic conditions. Besides, two control groups will be included: one of 3 unused healing abut-ments, and the other of just medium. After 10 days at 37°C under a 5% CO2 100 μl of the broth will be plated on solid media (Brain Infusion Agar, BHIA) and Columbia Blood agar to test for sterility. The remaining volume will be centrifuged, the sediment fixed, and a Gram stain performed to discard the presence of non-cultivable micro-organisms. Moreover, to determine the presence of remaining organic material after the cleaning and sterilizing treatments, the bioburden will be determined by measuring total organic carbon (TOC) in another 10 previously used healing abutments, cleaned and sterilized, that will be submerged in Milli-Q water and sonicated

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Effect on osseointegration of two implant macro-designs: A histomorphometric analysis of bicortically installed implants in different topographic sites of rabbit's tibiae

Background: To evaluate the effect of two different implant macro-designs on the sequential osseointegration at bicortically installed implants in the rabbit tibia. A further aim is to compare the osseointegration at different topographic zones. Material and Methods: 27 New Zealand rabbits were implemented. Two implants, one for each macro-design (Ticare Inhex(R) or Ticare Quattro(R), Mozo-Grau, Valladolid, Spain), were randomly implanted in the diaphysis or metaphysis of each tibia. The flaps were sutured to allow a submerged healing. The animals were sacrificed after 2, 4 or 8 weeks. Ground sections were prepared and analyzed. Results: No statistically significant differences were found between the two groups for newly formed bone in contact with the implant surface, being about 16%, 19% and 33% in both groups, after 2, 4, and 8 weeks of healing. Bone apposition was slightly higher in the diaphysis, reaching values of 36.4% in the diaphysis, and 29.3% in the metaphysis at 8 weeks of healing. It was observed that the implant position showed a statistical significance regarding BIC values at 4 and 8 weeks (p < 0.05). Multivariate analysis fails to detect statistical significant differences for the interaction between implant designs and topographic site. Ticare Quattro(R) design had a slight better BIC values at diaphysis sites across healing stages, but without reaching a statistical significance. Conclusions: The both implant macro-designs provided similar degrees of osseointegration. Bone morphometry and density may affect bone apposition onto the implant surface. The apposition rates were slightly better in diaphysis compared to metaphysis

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Development and viability of biofilms grown on experimental abutments mimicking dental implants: An in vivo model

Background: To determine whether an experimental abutment mimicking the macro- and microstructure of a dental implant is a suitable method for recovering biofilm, and to describe the features of biofilms formed around such abutments on healthy implants. Material and Methods: Experimental abutments were used in 15 patients without peri-implant diseases. After 14 days' absence of dental hygiene in this area, the abutments were retrieved and analyzed through confocal laser scanning microscopy and scanning electron microscopy. The biofilm formation on the surface of the first 5 abut-ments was determined by a fluorescence-staining method using SYTO9 nucleic acid stain. In order to study the biofilm's coverage and vitality, 10 additional abutments were assessed using live & dead bacterial viability. Descriptive and bivariate analyses of the data were performed. Results: A global plaque coverage of the abutments was observed in all cases. The submucosal area of the abutment was mostly covered with biofilm (over 21%). Moreover, significant differences between supra- and subgingival locations were detected. Conclusions: This in vivo experimental model allows detailed observation of the extensive plaque growth found on exposed experimental abutments mimicking dental implants when hygiene measures are absent. The biofilm cover-age is significantly higher in the supragingival zone than in the subgingival portion

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Combination Therapy of Clinically Approved Antifungal Drugs Is Enhanced by Conjugation with Silver Nanoparticles

Silver nanoparticles (SN) have been recently developed as a new class of antimicrobial agents against numerous pathogenic microorganisms. SN have also been used as efficient drug delivery systems and have been linked with increasing drug potency. Here, we demonstrated the enhanced antifungal efficacy of nystatin (NYT) and fluconazole (FLU) after conjugation with SN. The antifungal bioactivity of NYT- and FLU-coated SN was evaluated against Candida albicans ATCC 10231 and Aspergillus brasiliensis ATCC 16404 by the agar tube dilution method. The aim of this study was to determine and compare the antifungal efficacy of NYT and FLU with their SN and, finally, the combination of both nanoparticles as NYT-SN + FLU-SN against pathogenic fungi. The results indicated that all test samples showed a dose-dependent response against tested fungi. SN significantly enhanced the antifungal effects of NYT and FLU as compared to drugs alone. We observed a remarkable increase in the percent inhibition of both fungi (90-100%) when treated with a combination of both nanoparticles NYT-SN + FLU-SN at 200 μg/mL only. Furthermore, the morphological modifications occurred at the surface of fungal species were also analyzed by atomic force microscopy (AFM) and scanning electron microscopy (SEM). While tested against primary human cell line, all SN showed negligible cytotoxicity. Hence, these results suggest that the combination of SN with NYT and FLU may have clinical implications in the treatment of fungal infections. However, in vivo studies are needed before recommending the use of these nanoparticles safely in clinical situations

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La evaluación topográfica de las superficies de los implantes de titanio / Topographic evaluation of the titanium implant surfaces

La superficie de los implantes es muy importante para la oseointegración. La superficie rugosa de titanio puede influir en los resultados experimentales y clínicos. Diferentes instrumentos y técnicas de mediciones pueden influir notablemente en los resultados de la caracterización topográfica de los implantes. Las superficies han sido documentadas mediante microscopio electrónico de barrido. La interferometría de luz blanca puede identificar las irregularidades en la superficie por cambios en la luz reflejada. La composición química de las superficies puede ser determinada por la técnica de espectroscopía fotoelectrónica de rayos X. La composición química refleja los procedimientos de la fabricación de los implantes. Una variedad de elementos y compuestos químicos no relacionados con la composición del titanio pueden encontrarse en algunos tipos de implantes; como material inorgánico (ej. cloruro de sodio) y compuestos orgánicos de carbono que pueden deberse a la contaminación durante la fabricación y el almacenaje. Conclusiones: Las modificaciones en la topografía y en la composición química de la superficie de los implantes constituye un importante campo en la implantologia oral experimental y clínica

Implant surface is very important for the osseointegration. Roughened surface titanium may influence in experimental and clinical results. Different measures instruments and techniques strongly influence the outcome of a topographic characterization of surface implant. Surfaces has been documented by scanning electron microscopy. White light interferometer may identify the surface irregularities that cause phase changes in the reflected light. The surfaces chemical composition was determined using a technique of X-ray photoelectron spectroscopy. Chemical composition reflect the type of fabrication procedures applied to implants. A variety of elements and chemical compounds not related to the titanium composition were found on some implant types. They ranged from inorganic material (i.e. sodium chloride) to specific organic as carbon compounds believed to be due to contamination during fabrication or storage. The experimental findings are believed to make a contribution to a better understanding of the interplay between industrial fabrication procedure and physico-chemical implant surface properties. Conclusions: The topographic and chemical composition modifications of surface implants constitute an important field in experimental and clinical implant dentistry

La biología de la oseointegración en los implantes postextraccion / The biology of osseointegration in postextraction implants

Los fenómenos biológicos de la oseointegración comprenden un proceso de reabsorción y formación ósea que ha sido descrito en estudios histológicos en animales y humanos. La extracción de dientes seguida de la inserción de implantes inmediatos provoca alteraciones en las dimensiones del hueso alveolar con gaps horizontales y verticales entre las paredes del alveolo y el implante. La reabsorción de la pared vestibular parece ser más pronunciada. Esta deshicencia ósea despues de la inserción de implantes postextracción ha sido corroborada en experimentos con animales y confirmada en studios clínicos con pacientes. Diversos factores pueden afectar a la respuesta biológica de los tejidos periimplantarios y el contacto hueso-implante en los alveolos postextracción como la densidad de hueso, la superficie y el diseño del implante y la técnica quirúrgica. Conclusión: La investigación experimental y clínica indica que la inserción de implantes en alveolos frescos no perjudica la remodelación de los tejidos periimplantarios. Sin embargo, tiene lugar la reabsorción ósea tanto de la pared vestibular como lingual

The biology of osseointegration involve a process of healing with bone resorption and bone apposition, as described histologically in animal and human studies. The removal of teeth followed by immediate implant placement results in marked alterations to alveolar ridge dimensions as well as horizontal and vertical gaps between the bone walls and the implant. Resorption of the buccal plate was seen to be more pronounced; this bone dehiscence following implant placement corroborates findings reported in animal experiments and confirmed in clinical studies with patients. Several factors affecting the biologic response of peri-implant tissues and bone-implant contact in postextraction implants as original bone density, implant surfaces, implant design and surgical technique. Conclusions: Experimental and clinical research studies suggest that the insertion of implant in fresh sockets does not jeopardize remodeling of periimplant tissues. However, bone resorption can be expected on both the lingual and buccal aspects

La oseointegración de implantes de titanio con diferentes superficies rugosas / Osseointegration of titanium implant with several rough surfaces

La superficie de los implantes es muy importante para conseguir la oseointegración. Existen muchos tipos de superficies en los implantes dentales. La investigación en superficie de implantes comienza con la superficie mecanizada. La superficie rugosa incrementa la adherencia celular y muestra una mayor área de contacto hueso-implante. El recubrimiento con plasma de titanio e hidroxiapatita fueron métodos comunes para modificar la rugosidad de la superficie. Más recientemente, el arenado (ej. alúmina) y el grabado ácido (ej. chorhídrico, sulfúrico, nítrico) son otros procesos que pueden incrementar la superficie rugosa de los implantes. Más recientemente, la tecnología ha comenzado en la implantología oral con el desarrollo de superficies porosas que manifiestan una mejor respuesta osteogénica e incrementa la unión mecánica hueso-titanio. La oseointegración parece estar influenciada por los modelos de especies animales. En el conejo el proceso es más rápido que en el perro, y en el perro es más rápido que en el hombre. La incorporación de nuevos materiales y procesos técnicos en la investigación sobre superficies de implantes ofrecen nuevas posibilidades de mejorar su respuesta tisular y su potencial óseo regenerativo. Conclusiones: El tratamiento de la superficie de los implantes constituye un importante campo en futuras investigaciones de la implantología oral mediante los estudios de experimentación

Implant surface is very important for enhance the osseointegration. They are many types of dental implant surfaces. Implant surface research begins with machined surface. Roughened surface titanium increase cell adhesion and exhibit stronger bone-implant contact area. Plasma-spray and hydroxyapatite coating were common methods for rough surface modification. Most recently, blasting (i.e. alumina) and acid-etching (i.e. hydrochloric, sulphuric and nitric) are another process by which surface roughness can be increased. Most recently, technology begins in implant dentistry with the development of porous surfaces that manifest better osteogenic response and increase bone-titanium mechanical interlocking. Osseointegration appeared to be strongly influenced by the animal species model. The rabbit model was faster compared to the dog model, and the dog model was faster the human model. The introduction of new materials and new technical process in dental surfaces research offering new possibilities for better tissue response and bone regenerative potential. Conclusions: The surface modifications of titanium constitute an important field for future research of implant dentistry by experimental studies

Radiosensitization by gold nanoparticles

Recent years brought increasing use of gold nano particles (GNP) as a model platform for interaction of irradiation and GNPs aiming radiosensitization. Endocytosis seems to be one of the major pathways for cellular uptake of GNPs. Internalization mechanism of GNPs is likely receptor-mediated endocytosis, influenced by GNP size, shape, its coating and surface charging. Many showed that DNA damage can occur as a consequence of metal-enhanced production of low energy electrons, Auger electrons and alike. Kilovoltage radiotherapy (RT) carries significantly higher dose enhancement factor (DEF) that is observed with megavoltage irradiations, the latter usually been at the order of 1.1-1.2. Higher gold concentrations seem to carry higher risk of toxicity, while with lower concentrations the DEF can be reduced. Adding a chemotherapeutic agent could increase level of enhancement. Clinical trials are eagerly awaited with a promise of gaining more knowledge deemed necessary for more successful transition to widespread clinical practice (AU)

Effect of three prophylaxis methods on surface roughness of giomer

Objectives: Plaque and stains are removed by prophylaxis methods from tooth surfaces. Since prophylaxis methods can have a detrimental effect on the surface finish of restorations, the aim of this in vitro study was to investigate the effect of three prophylaxis methods, including pumice with rubber cup, pumice with brush, andair-powder polishing device (APD) on the surface roughness of giomer.Study design: Sixty four cylindrical giomer (Beautifil II, Shofu) samples with a diameter of 6 mm and a heightof 2 mm were used. Subsequent to a 3-month period of storage in distilled water at 37ºC, the samples were randomly divided into four groups of 16. In group 1 (control), no prophylaxis procedure was carried out. In groups2 to 4 the samples were exposed to pumice with rubber cup, pumice with brush, and APD prophylaxis methods,respectively. The surface roughness of the samples was measured using a profilometer and the effect of different prophylaxis methods on surface topography was characterized by atomic force microscopy (AFM). All data were analyzed by one-way ANOVA and Duncan’s post hoc test at a significance level of P < 0.05.Results: There were statistically significant differences in surface roughness among the groups (P < 0.0005).Furthermore, in pairwise comparisons there were statistically significant differences between all the groups (P <0.05). The roughest surfaces, in descending order, were observed with the use of APD, pumice with brush, and pumice with rubber cup.Conclusions: The use of different prophylaxis methods resulted in an increased surface roughness of giomer compared with the control group. APD prophylaxis exerted the most detrimental effects on the surface of giomer (AU)

Early bone healing around implant surfaces treated with variationsin the resorbable blasting media method. A study in rabbits

Objective: this study aimed to histomorphologically and histomorphometrically evaluate the in vivo response tothree variations in the resorbable blasting media (RBM) surface processing in a rabbit femur model. Study Design:screw root form implants with 3.75 mm in diameter by 8 mm in length presenting four surfaces (n=8 each):alumina-blasted/acid-etched (AB/AE), bioresorbable ceramic blasted (TCP), TCP + acid etching, and AB/AE +TCP were characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM). The implantswere placed at the distal femur of 8 New Zeland rabbits, remaining for 2 weeks in vivo. After sacrifice, theimplants were nondecalcified processed to 30 micro m thickness slides for histomorphology and bone-to-implantcontact (BIC) determination. Statistical analysis was performed by one-way ANOVA at 95% level of significanceconsidering implant surface as the independent variable and BIC as the dependent variable. Results: SEM andAFM showed that all surfaces presented rough textures and that calciu-hosohate particles were observed at theTCP group surface. Histologic evaluation showed intimate interaction between newly formed woven bone and allimplant surfaces, demonstrating that all surfaces were biocompatible and osseoconductive. Significant differencesin BIC were observed between the AB/AE and the AB/AE + TCP, and intermediate values observed for the TCPand TCP + Acid surfaces. Conclusion: irrespective of RBM processing variation, all surfaces were osseoconductiveand biocaompatible. The differences in BIC between groups warrant further bone-implant interface biomechanicalcharacterization (AU)

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Torque de desinserción y propiedades fisico-químicas de implantes dentales grabados con ácidos fluorhídrico y nítrico. Estudio experimental en perros Beagle / Removal torque and physico-chemical characteristics of dental implants etched with hydrofluoric and nitric acid. An experimental study in Beagle dogs

Objetivo: Estudiar la composición, características superficiales y respuesta al torque de desinserción de una superficie implantaria tratada inicialmente con ácido fluorhídrico y posterior pasivado con ácidos fluorhídrico y nítrico.Diseño del estudio: En una primera fase, se seleccionaron 12 implantes en los que se estudiaron las características fisico-químicas mediante mediciones de energía dispersa de rayos X (EDS), microscopio electrónico de barrido y análisis de XPS (espectrometría de fotoelectrones). Asimismo, se colocaron 24 implantes –doce de 8 mm y doce de 10 mm de longitud-, en seis perros beagle, en los que tras un período de reposo, se procedió a la retirada de 12 implantes a las seis semanas y los 12 restantes a las doce semanas, mediante un calibrador de torque Gauge TonichiR modelo BGT150CN-S -con un rango de registro de fuerza de 0 a 150 Ncm.Resultados: El análisis de la composición química superficial mediante EDS sólo mostró la presencia de titanio en las superficies grabadas. En el análisis mediante XPS, al igual que sucede con las superficies de otros implantes dentales, aparecieron trazas de otros elementos presentes en la superficie, fundamentalmente de carbono.La morfología de la superficie tras el doble grabado con ácido, permitió observar la rugosidad creada por el ataque ácido, con una morfología bastante homogénea. Los valores de rugosidad obtenidos fueron superiores al micrómetro.Los valores medios encontrados para el torque de desinserción, a las seis semanas, fueron de 79,7 Ncm para los implantes de 8 mm de longitud y 115 Ncm para los implantes de 10 mm. A las doce semanas, estos valores incrementaron hasta 101,2 Ncm para los implantes de 8 mm y 139,7 Ncm para los implantes de 10 mm de longitud.Conclusiones: El grabado con ácido fluorhídrico y nítrico, posee características superficiales óptimas y comparables al de otras superficies. Los valores de torque de desinserción abren la posibilidad para su aplicación en clínica humana para procedimientos de carga precoz o inmediata

Objective: To study the composition, surface characteristics and response to removal torque of an implant surface subjectedto hydrofluoric acid etching and posterior passivating with hydrofluoric and nitric acid.Study design: Twelve implants were initially selected and their physico-chemical characteristics were evaluated by means of energy-dispersive X-rays (EDS), scanning electron microscopy (SEM) and photoelectron spectroscopy (XPS). In addition, 24 implants – 12 measuring 8 mm and 12 measuring 10 mm in length – were implanted in 6 Beagle dogs. Twelve implants were removed after a recovery period of 6 weeks, followed by removal of the remaining 12 implants after 12 Medeweeks,using a torque calibrator (Gauge Tonichi® model BGT150CN-S) with a force registry range of 0-150 Ncm.Results: EDS analysis of the surface chemical composition only revealed the presence of titanium in the etched surfaces. In the same way as with the surfaces of other dental implants, XPS analysis revealed traces of other elements present in the surface, fundamentally carbon. Following dual acid etching, the surface showed the roughness resulting from acid action, with a morphology that proved to be quite homogeneous. The roughness values obtained exceeded 1 ìm. The mean removal torque values after 6 weeks were 79.7 Ncm for the 8 mm implants and 115 Ncm for the 10 mm implants. After 12 weeks, these values increased to 101.2 Ncm and 139.7 Ncm, respectively.Conclusions: Hydrofluoric and nitric acid etching affords optimum surface characteristics comparable to those of other surfaces. The recorded removal torque values raise the possibility of human clinical application for early or immediate loading procedures