In vivo effect of UV-photofunctionalization of CoCrMo in processes of guided bone regeneration and tissue engineering.

Photofunctionalization of implant materials with ultraviolet (UV) radiation have been subject of study in the last two decades, and previous research on CoCrMo discs have showed good results in terms of bioactivity and the findings of apatite-like crystals in vitro. In the current study, CoCrMo domes were photofunctionalized with UV radiation of 254 nm on their internal faces during 24 hr; they were implanted in rabbit tibia and remained for 3, 4, and 6 weeks. The potential to induce bone formation beneath the dome-shaped membranes was evaluated through morphometric, histologic, and density measurements; and the results were compared with those obtained under control untreated domes. Higher density values were observed for irradiated domes at 3 weeks, whereas higher volumes were obtained under photofunctionalized domes for longer periods (4 and 6 weeks). Histologically, woven bone was formed by endochondral ossification in all cases; differences in the architecture and size of the trabeculae and in the number of osteoblasts were noted between irradiated and non-irradiated samples. The UV radiation of 254 nm generated a larger bone volume fraction compared to that found in the absence of UVC radiation and induced an increase of density in the early stages of healing, leading to a better initial bone quality and improved osseointegration.

CoCrMo alloy as biomaterial for bone reconstruction in oral and maxillofacial surgery: a scoping review / Aleación de CoCrMo como biomaterial para la reconstrucción ósea en cirugía oral y maxilofacial: una revisión del alcance

Background: Osseointegration allowed for a breakthrough in biomaterials and techniques and it has contributed to increased application of dental implants. However, insufficient bone level is a frequent problem and it creates an anatomically less favourable base for implant placement. The first surgical procedure should comprise the reconstruction of the alveolar bone height. CoCrMo alloys are nowadays considered as highly corrosion resistant and biocompatible materials in dentistry, and therefore has been suggested as a suitable biomaterial for guided bone regeneration and tissue engineering. Aim: To determine the use of CoCrMo alloy for implantable devices in oral and maxillofacial surgery and to discuss the potential of this alloy for bone regeneration and repair through a scoping review. Material and methods: The search was done by using various databases including PubMed, Thomson Reuters and Scopus. We selected English literature related to studies reporting the CoCrMo properties and manufacturing processes and findings related to bone-forming techniques. Data was compared qualitatively. Results: 90 studies were selected according to the inclusion criteria. We reported different manufacturing techniques and their advantages related to mechanical, chemical and biocompatible properties. Conclusion: Improved tissue reactions of CoCrMo implant devices can be acquired by the application of novel techniques and surface modifications. Moreover, several processes have demonstrated to improve the in vitro and in vivo biocompatibility of the CoCrMo alloy to promote the attachment, proliferation and guided differentiation of seeding cells.

Antecedentes: La osteointegración ha permitido un gran avance en biomateriales y técnicas, y ha contribuido un mayor uso de implantes dentales. Sin embargo, la existencia de un nivel óseo insuficiente es un problema frecuente y crea una base anatómicamente menos favorable para la colocación de implantes. El primer procedimiento quirúrgico debe comprender la reconstrucción de la altura del hueso alveolar. Las aleaciones de CoCrMo se consideran hoy en día como materiales altamente resistentes a la corrosión y biocompatibles en odontología y, por lo tanto, se ha sugerido como un biomaterial adecuado para la regeneración ósea guiada y la ingeniería de tejidos. Objetivo: Determinar el uso de la aleación CoCrMo para dispositivos implantables en cirugía oral y maxilofacial y discutir sobre el potencial de esta aleación para la regeneración y reparación ósea a través de una revisión de alcance. Material y Métodos: La búsqueda se realizó utilizando varias bases de datos, incluidas PubMed, Thomson Reuters y Scopus. Se seleccionó literatura inglesa relacionada con estudios que informan sobre las propiedades de CoCrMo y los procesos de fabricación y los hallazgos relacionados con las técnicas de formación de huesos. Los datos se compararon cualitativamente. Resultados: Se seleccionaron 90 estudios según los criterios de inclusión. y se reportaron diferentes técnicas de fabricación y sus ventajas relacionadas con propiedades mecánicas, químicas y biocompatibles. Conclusión: Las reacciones tisulares mejoradas de los dispositivos de implante CoCrMo pueden adquirirse mediante la aplicación de nuevas técnicas y modificaciones de la superficie. Además, varios procesos han demostrado mejorar la biocompatibilidad in vitro e in vivo de la aleación CoCrMo para promover la unión, proliferación y diferenciación guiada de las células de siembra.

Image-based analysis of trabecular bone in osteoporotic rabbits: correlation of morphological features and bone mineral density profile.

OBJECTIVE: To analyse a set of morphological features from digital radiographs (RX) and bone mineral density (BMD) values estimated from quantitative computerized tomography scans (QCT scans) of the knee joint of an osteoporotic rabbits, and to determine the relationship and correlation of these variables to be considered as an alternative diagnosis method. METHODS: The knee joint of rabbits (N = 9 ovariectomized and injected with of methylprednisolone sodium succinate (OVX + MPSS) and 3 sham operated healthy controls) were subjected to radiographic examination before the beginning of the study and after 6 weeks; after sacrifice, they were immediately scanned with a 64-channel CT. A set of morphological features was extracted from RX images and then subjected to Principal Component Analysis (PCA); BMD-values were calculated at different depths from the articular surface of the femur and the tibia. The selected morphological variables and the BMD values were correlated in order to determine useful information in medical diagnostics. RESULTS: Ten morphological variables explained 80.39% of the total variability, but only some of them demonstrated significant differences between baseline and OVX + SSMP states and between OVX + SSMP and control. Spearman analysis showed higher positive and negative correlation of these parameters among them (r = 0.67, 0.81, 0.83 and 1); and a moderate correlation with the BMD values (r = 0.50, 0.52, 0.52 and 0.55) during the progression of osteoporosis (OP). CONCLUSION: The Spearman's rank test supported the overall significant correlation between both, the morphological features and BMD values, making them as a reliable alternative option to the diagnosis of osteoporosis.

Influence of Chromium-Cobalt-Molybdenum Alloy (ASTM F75) on Bone Ingrowth in an Experimental Animal Model.

Cr-Co-Mo (ASTM F75) alloy has been used in the medical environment, but its use as a rigid barrier membrane for supporting bone augmentation therapies has not been extensively investigated. In the present study, Cr-Co-Mo membranes of different heights were placed in New Zealand white, male rabbit tibiae to assess the quality and volume of new bone formation, without the use of additional factors. Animals were euthanized at 20, 30, 40, and 60 days. Bone formation was observed in all of the cases, although the tibiae implanted with the standard membranes reached an augmentation of bone volume that agreed with the density values over the timecourse. In all cases, plasmatic exudate was found under the membrane and in contact with the new bone. Histological analysis indicated the presence of a large number of chondroblasts adjacent to the inner membrane surface in the first stages, and osteoblasts and osteocytes were observed under them. The bone formation was appositional. The Cr-Co-Mo alloy provides a scaffold with an adequate microenvironment for vertical bone volume augmentation, and the physical dimensions and disposition of the membrane itself influence the new bone formation.

Improvement of Cr-Co-Mo Membrane Surface Used as Barrier for Bone Regeneration through UV Photofunctionalization: An In Vitro Study.

Although there are several studies of the ultraviolet (UV) light-mediated photofunctionalization of titanium for use as implant material, the underlying mechanism is not fully understood. However, the results of in vitro and in vivo studies are very encouraging. The use of UV photofunctionalization as a surface treatment on other implant materials, as the Cr-Co-Mo alloy, has not been explored in depth. Using sandblasted Cr-Co-Mo discs, the surface photofunctionalization was studied for ultraviolet A (UVA, 365 nm) and ultraviolet C (UVC, 254 nm), and the surfaces were evaluated for their ability to sustain hydroxyapatite crystal growth through incubation in simulated body fluid for a seven-day period. The variation of the pre- and post-irradiation contact angle and surface composition was determined through the quantification of the weight percentage of Ca and P crystals by the EDAX ZAF method (EDS). Statistically significant differences (p < 0.05) were found for samples irradiated with UVA over 48 h, corresponding with hydrophilic surfaces, and the same result was found for samples exposed to 3 h of UVC. Superhydrophilic surfaces were found in samples irradiated for 12, 24 and 48 h with UVC. The decrease in the carbon content is related with the increase in the surface content of Ca and P, and vice versa over the Cr-Co-Mo surfaces.

Localized tissue mineralization regulated by bone remodelling: A computational approach.

Bone is a living tissue whose main mechanical function is to provide stiffness, strength and protection to the body. Both stiffness and strength depend on the mineralization of the organic matrix, which is constantly being remodelled by the coordinated action of the bone multicellular units (BMUs). Due to the dynamics of both remodelling and mineralization, each sample of bone is composed of structural units (osteons in cortical and packets in cancellous bone) created at different times, therefore presenting different levels of mineral content. In this work, a computational model is used to understand the feedback between the remodelling and the mineralization processes under different load conditions and bone porosities. This model considers that osteoclasts primarily resorb those parts of bone closer to the surface, which are younger and less mineralized than older inner ones. Under equilibrium loads, results show that bone volumes with both the highest and the lowest levels of porosity (cancellous and cortical respectively) tend to develop higher levels of mineral content compared to volumes with intermediate porosity, thus presenting higher material densities. In good agreement with recent experimental measurements, a boomerang-like pattern emerges when plotting apparent density at the tissue level versus material density at the bone material level. Overload and disuse states are studied too, resulting in a translation of the apparent-material density curve. Numerical results are discussed pointing to potential clinical applications.

Changes in morphology of alveolar buccal walls following atraumatic internal root fragmentation / Cambios en la morfología de las paredes alveolares bucales después de fragmentación radicular interna atraumática

The buccal alveolar wall represents the most important structure to provide shape and volume of the alveolous following tooth extraction. The aim of the study was the evaluation of buccal alveolar bone structures following minimally invasive surgery. In 15 patients (3 male, 12 female), aged 20­67 years, 3 central incisors, 5 lateral incisors, and 7 bicuspids were removed using flapless enucleation. The enucleation comprised endoscopically assisted mesiodistal root sectioning with inward fragmentation of the oral and apical parts followed by internal reduction of the buccal root lamella. Buccal bone height before extraction was 10.61 mm, following extraction 10.50 mm. Crestal width of the buccal bone plate was 1.11 mm before and 1.40 mm after tooth removal. Apical buccal bone width before was 0.66 mm and after extraction 0.40 mm. Gingival height was 13.58 mm before and 13.56 mm following extraction. Following transalveolar enucleation, the buccal alveolar bone wall remains unchanged concerning height and crestal width.

La pared alveolar bucal representa la estructura más importante para proveer la forma y el volumen de los alveólos dentales posterior a la extracción dental. El objetivo del estudio fue evaluar las estructuras de hueso alveolar bucal después de la cirugía mínimamente invasiva. En 15 pacientes (3 hombres, 12 mujeres), con edades entre 20 a 67 años, 3 incisivos centrales, 5 incisivos laterales y 7 premolares fueron removidos utilizando enucleación sin colgajo. La enucleación comprende el seccionamiento mesio-distal de la raíz dental endoscópicamente asisitido a través de fragmentación interna de la porción lingual y apical radicular y posteriomente una reducción interna de la lamela de raíz bucal. La altura ósea bucal antes de la extracción fue 10,61 mm y después de la extracción fue 10,50 mm. La anchura de la cresta ósea bucal fue 1,11 mm y 1,40 mm después de la extracción del diente. El grosor del hueso apical antes de la extracción fue 0,66 mm y 0,40 mm después de la extracción. La altura gingival fue 13,58 mm antes de la extracción y 13,56 mm después de la extracción. Después de la enucleación transalveolar, la pared del hueso alveolar bucal se mantiene sin cambios en relación con la altura y del grosor del reborde alveolar.

Bone augmentation in rabbit tibia using microfixed cobalt-chromium membranes with whole blood, tricalcium phosphate and bone marrow cells.

To assess bone augmentation based on a non-critical defect, 1.5 mm deep cobalt-chromium (Co-Cr) barrier membranes were placed on seven adult California rabbits with three different grafting situations: whole blood, whole blood with tricalcium phosphate (TCP), and TCP mixed with bone marrow cells. Macroscopic assessment of the animals was performed once a week and densitometric studies were performed once a month. Three months post-surgery, after detaching the membranes, tibias were sectioned and followed the routine laboratory processing for decalcified sections, with inclusion in paraffin and staining by hematoxylin and eosin technique. Bone augmentation was observed for each animal, even sometimes over the Co-Cr membranes. Compact bone was mostly observed for every situation, with a higher cellular activity on those samples with bone grafts. This could be due to the presence of graft remains at the growth area. It could be concluded that blood supply to the site providing growth factors by the blood clot formation, and the placement of an osteoconductive non-resolvable membrane that favors osseoinduction, may be sufficient elements to achieve bone augmentation in a period of three months in rabbit tibia.

Bone Augmentation in Rabbit Tibia Using Microfixed Cobalt-Chromium Membranes with Whole Blood and Platelet-Rich Plasma.

BACKGROUND: Bone augmentation is a subject of intensive investigation in regenerative bone medicine and constitutes a clinical situation in which autogenous bone grafts or synthetic materials are used to aid new bone formation. METHOD: Based on a non-critical defect, Co-Cr barrier membranes were placed on six adult Fauve de Bourgogne rabbits, divided into two groups: whole blood and PRP. Three densitometric controls were performed during the experiment. The animals were euthanized at 30, 45, 60, and 110 days. The presence of newly formed bone was observed. Samples for histological studies were taken from the augmentation center. RESULTS: External and internal bone tissue augmentation was observed in almost all cases. Significant differences between PRP- and whole blood-stimulated bone augmentation were not observed. At 60 days, bones with PRP presented higher angiogenesis, which may indicate more proliferation and cellular activity. CONCLUSION: PRP activates the bone regeneration process under optimized conditions by stimulation of osteoblast proliferation after six weeks, when a significant difference in cellular activity was observed. Membranes could stimulate bone augmentation at the site of placement and in the surrounding areas.

Influence of implant diameter in the displacement of dental implants in trabecular bovine bone under a static lateral load: experimental results and computational modeling.

PURPOSE: Primary stability and micromovement of dental implants depend on structural properties of the surrounding bone and on implant dimension and design. The purpose of this study was to provide objective data for the influence of implant diameter on the displacement of titanium screw implants. MATERIALS AND METHODS: Ninety Semados implants (length 15 mm, diameter 3.25, 3.75, and 4.5 mm; Bego, Bremen, Germany) were inserted in trabecular bone specimens. All implants were inserted with a torque up to 30 N·cm and loaded horizontally with 10, 20, and 30 N for 2 seconds. RESULTS: All implants showed primary stability. With increasing force, a gradual increase of micromovement was observed (Kruskal-Wallis test, P = 0.000). No significant differences were found (Kruskal-Wallis test, P = 0.148) comparing different diameters for every force. CONCLUSIONS: Variation of the diameter of standard implants between 3.25 and 4.5 mm does not seem to influence the primary stability in trabecular bone specimen. Differences between experimental and computational results may be due to the simplification used when modeling.

Rigid occlusive titanium barriers for alveolar bone augmentation: two reports with 24-month follow-up.

Titanium barriers have been used for guided bone regeneration in preclinical and preliminary clinical reports as a possible alternative to bone grafting. In two cases with lateral bone defects, rigid titanium barriers were used to provide a secluded space in conjunction with bone substitutes. Sufficient lateral bone volume was generated for implant placement, and no complications were observed during 2 years of follow up. In conclusion, space-making stiff titanium barriers may be applied successfully for lateral alveolar crest augmentation.

Bone augmentation with occlusive barriers and cortical particulate allograft in transverse maxillary defects: a pilot study / Aumento óseo con barreras oclusivas y aloinjerto cortical particulado en defectos maxilares transversales: un estudio piloto

The centripetal resorption of maxilla is a continuous process after tooth loss. For treatment of deficient bone sites, autologous bone grafts may be used, as an alternative, biomaterials can be applied which do not require intra or extraoral donor sites. The present report describes the use of occlusive barriers and cortical particulate allograft in transverse maxillary defects. This surgical approach was performed in five patients (4 females and 1 male, aged 20 to 37 years). Clinical results show that sufficient hard tissue was formed to allow implant born rehabilitation in the former insufficient bone sites. Histological evaluation revealed small amounts of newly formed bone with a predominance of collagen fibrous tissue and mature bone with very little cellular elements. Depending on the original site situation, the minimally invasive approach with occlusive barrier and cortical particulate allograft may be applied. We observed a mean of 2.3, 2.7 and 2.9 mm in bone gain for ridge, middle and apical area, respectively.

La reabsorción centrípeta del maxilar es un proceso continuo después de la pérdida dentaria. Para el tratamiento de sitios óseos deficientes, se pueden utilizar injertos de hueso autólogo; como alternativa, se puede aplicar biomateriales, que no requieren sitios donantes intra o extraorales. El presente reporte describe la utilización de barreras oclusivas y aloinjerto cortical particulado en defectos maxilares transversales. Este abordaje quirúrgico fue realizado en cinco pacientes (4 mujeres y 1 hombre, de 20 hasta 37 años de edad). Los resultados clínicos muestran que se formó suficiente tejido duro para permitir la rehabilitación de implantes en los sitios de hueso insuficiente. La evaluación histológica reveló pequeñas cantidades de hueso neoformado con predominantes fibras colágenas y hueso maduro con muy pocos elementos celulares. Dependiendo de la situación del sitio original, se puede aplicar un abordaje mínimamente invasivo con barreras oclusivas y aloinjerto cortical particulado. Se pudo observar un aumento óseo promedio de 2,3, 2,7 y 2,9 mm para las regiones de la cresta ósea, zona media y apical, respectivamente.

Displacement of dental implants in trabecular bone under a static lateral load in fresh bovine bone.

AIM: The study aims to provide objective data for the displacement of titanium screw implants in trabecular bone specimens. One hundred Semados implants (Bego, Bremen, Germany) were inserted in bovine type IV bone specimens. All implants had a diameter of 3.75 mm; 50 implants had a length of 8.5 mm and 50 implants had a length of 15 mm. Insertion torque was determined at intervals of 10, 20, and 30 Ncm. Implants were loaded horizontally with 10, 20, and 30 N for 2 seconds. An indicator strip was attached to the implant abutment to allow direct observation of implant movement relative to the bone surface. Horizontal displacement was assessed with an accuracy of measurement of 10 µm. Seven implants got lost by visible loosening. Degree of displacement was subject to evaluation with all others. Those implants showed a mean displacement of 59 µm for 10 N (n = 100), 173 µm for 20 N (n = 99), and 211 µm for 30 N (n = 93). The mean displacement of 15-mm implants (16, 37, 51 µm) was significantly lower compared with 8.5-mm implants (103, 311, 396 µm) corresponding to 10, 20, and 30 N as lateral loads. CONCLUSIONS: Displacement of screw implants in trabecular bone can be detected and visualized using commercially available endoscopes with a high magnification. A lateral load of 20 N indicates a mean displacement of over 100 µm and therefore results in a critical displacement.

Endoscopically assisted root splitting (EARS): method and first results / Sección radicular endoscópicamente asistida (SREA): método y primeros resultados

The trauma of surrounding bone structures during exodontia represents a mayor clinical shortcoming of conventional oral surgery. An alternative minimal invasive technique is presented to support aesthetic rehabilitation by conservation of alveolar bone walls. Endoscopically assisted root splitting (EARS) is a new technique for root removal wothout ostectomy. EARS consists of enlargment of the root canal, longitudinal root splitting, inward mobilisation and removal of the fragments under endoscopic control. In 24 patients (11 m, 13 f), aged 18-66 years, 8 central incisors, 6 lateral incisor, 5 canines and 5 bicuspids were removed using EARS. Endoscopic observation revealed complete maintenance of the buccal wall at it's preoperative level, control radiographs showed no apical root remnants. EARS has revealed to be a valuable tool to avoid alveolar crest trauma during exodontia...

El trauma de las estructuras circundantes al hueso durante la exodoncia representa una de las principales deficiencias de la cirugía cirugía oral convencional. Se presenta una técnica alternativa mínimamente invasiva para apoyar la rehabilitación estética mediante la conservación de las paredes alveolares óseas. La sección radicular endoscópicamente asistida (SREA) es una nueva técnica para la eliminación de raíz sin osteotomía. La SREA consiste en la ampliación del canal de la raíz, división longitudinal de la raíz, movilización hacia el interior y eliminación de los fragmentos bajo control endoscópico. En 24 pacientes (11 hombres y 13 mujeres), con edades comprendidas entre 18-66 años, 8 incisivos centrales, 6 incisivos laterales, 5 caninos y 5 premolares fueron eliminadas mediante SREA. La observación endoscópica reveló la mantención completa de la pared ósea bucal a nivel preoperatorios, y las radiografías de control no mostraron restos radiculares apicales. SREA se muestra como una valiosa herramienta para evitar el trauma de la cresta alveolar durante la exodoncia...

Immediate loading of freestanding implants using cortical satellite implants: 3-year results of an ongoing prospective study.

BACKGROUND: It has previously been demonstrated that immediate full occlusal loading of freestanding anterior implants can be performed using cortical satellite implants, obtaining a success rate similar to conventional protocols. The aim of this report was to present the outcomes after 36 months after initial placement. METHODS: Twenty patients received 2 single-standing titanium screw implants, which were stabilized during healing time with cortical satellite implants. Immediately after surgery, mandibular overdentures were placed using ball attachments. The satellite implants were removed after 3 months. RESULTS: Implant survival analysis showed a 100% success rate. The following parameters were assessed during the study: Periotest values, -5.89 (minimum: -7.00, maximum: -4.00); radiographic assessment of bone resorption, 0.51 mm (minimum: 0.00 mm, maximum: 1.50 mm); and pocket probing depth, 2.60 mm (minimum: 1.00 mm, maximum: 8.00 mm). CONCLUSIONS: The results suggest that immediate loading of freestanding implants stabilized with satellite implants is a successful concept at 3 years observation time.

Functional treatment of snoring based on the tongue-repositioning manoeuvre.

Orofacial biofunction comprises muscular and physical effects, which may contribute to stabilization of the oropharyngeal airway. The tongue-repositioning manoeuvre (TRM) provides physical stabilization of the tongue and the soft palate together with, as a prerequisite, a nasal breathing mode. The aim of the present study was to evaluate the influence of a TRM treatment concept on primary snoring. The TRM was used to achieve a closed biofunctional rest position of the orofacial system and to re-educate the nasal breathing pattern. Pressure indicating oral shields were used for home exercises as a biofeedback instrument and to support nocturnal mouth closure. Treatment was undertaken on 125 consecutive primary snorers [101 males, mean age 52.4 years, range 34-75, mean body mass index (BMI) 28.1, range 18.9-38.5, and 24 females, mean age 55.2 years, range 36-70, mean BMI 26.8, range 22.7-31.9]. Bed partner ranking was performed, and snoring was judged using a 10-cm visual analogue scale (VAS). The VAS score was 8.4 (range 6-10) before treatment and decreased to 4.1 (range 0-10) after treatment [mean observation time 4.6 months (1-10)]. Analysis of variance showed a significant influence of treatment in subjects with a normal body weight (BMI 18.5-25). The data provide evidence that dynamic stabilization of the orofacial system with the TRM in conjunction with nocturnal wear of an oral shield is beneficial for reducing the symptoms in primary snorers with a normal BMI.

Regeneración ósea guiada: microfijación de membranas reabsorbibles en tibia de conejo / Guided bone regeneration: microfixation or resorbable membranes in rabbit tibia

Se estudió la regeneración ósea guiada en tibia de conejo utilizando membranas de copolímero de PLA/PGA. Se realizaron osteotomías a nivel de metáfisis proximal tibial y algunas membranas fueron microfijadas. Las placas radiográficas a los 30 días mostraban signos de consolidación que se acentuaron con el transcurso de la experiencia. Pasados 6 meses de la cirugía, se observó macroscópicamente tejido óseo compacto uniforme. En las muestras con membrana no microfijadas se observ ó una depresión de la superficie tibial. Se observó formación de hueso harvesiano, tejido osteoide y estroma fibroso y restos de membranas de PLA/PGA con tejido adenomatoso levemente inflamatorio en todas las muestras. Los resultados sugieren que la microfijación impide el colpaso de estas membranas. Si bien a los seis meses se produjo una reparación ósea en todas las muestras, las membranas de PLA/PGA no se reabsorbieron completamente durante este período

Regeneración ósea guiada: microfijación de membranas reabsorbibles en tibia de conejo / Guided bone regeneration: microfixation or resorbable membranes in rabbit tibia

Se estudió la regeneración ósea guiada en tibia de conejo utilizando membranas de copolímero de PLA/PGA. Se realizaron osteotomías a nivel de metáfisis proximal tibial y algunas membranas fueron microfijadas. Las placas radiográficas a los 30 días mostraban signos de consolidación que se acentuaron con el transcurso de la experiencia. Pasados 6 meses de la cirugía, se observó macroscópicamente tejido óseo compacto uniforme. En las muestras con membrana no microfijadas se observ ó una depresión de la superficie tibial. Se observó formación de hueso harvesiano, tejido osteoide y estroma fibroso y restos de membranas de PLA/PGA con tejido adenomatoso levemente inflamatorio en todas las muestras. Los resultados sugieren que la microfijación impide el colpaso de estas membranas. Si bien a los seis meses se produjo una reparación ósea en todas las muestras, las membranas de PLA/PGA no se reabsorbieron completamente durante este período (AU)

Immediate occlusal loading of freestanding implants using cortical satellite implants: preliminary report of a prospective study.

Freestanding implants with mandibular overdentures are used frequently after 3 months' healing time. Immediate full loading may be applied to this approach if sufficient primary stability is provided. The present study evaluates the success rate of two single-standing interforaminal implants stabilized with cortical satellite implants and loaded immediately with overdentures. Twenty patients (five male and 15 female; age, 45-87 years) received two single-standing titanium screw implants (Semados, Bego, Bremen, Germany). All implants were stabilized during healing time with cortical satellite implants (2.0-mm bone screws; Medartis, Basel, Switzerland) via individual connectors attached to the implant abutment subgingivally. Mandibular overdentures were incorporated immediately after surgery using ball attachments as retentive elements. The patients were under no restrictions concerning diet and loading. The satellite implants were removed after 3 months. All implants were osseointegrated after 10 months' mean observation time. The mean Periotest value was -4.9, and the mean marginal bone loss was 0.7 mm. No dropouts were observed, and 19 of 20 patients would recommend the treatment to a close friend. Preliminary follow-up data indicate that cortical stabilization of two anterior mandibular implants with satellite implants leads to osseointegration of the implants under immediate load conditions with an overdenture. This concept contributes to reduction of prosthetic treatment costs and permits immediate enhancement of masticatory function.

In vitro evaluation of horizontal implant micromovement in bone specimen with contact endoscopy.

Primary stability of dental implants is mandatory for their osseointegration. A method is described that allows objective measurements of implant displacement in bone sites during lateral loading. Ten samples of bovine bone (2 cm x 2 cm) with bone type II, III, and IV according to Lekholm and Zarb were used for the experiment. Ten Semados dental implants of 15-mm length and 3.75-mm diameter were placed. All implants were loaded with lateral forces of 5, 10, 20, and 30 N through 8-mm abutments for 2 seconds each. Lateral displacement was observed by means of contact endoscopy. Micromovement was detected with the help of a transmitter strip attached to the abutment. Endoscopic images were processed digitally and microdisplacement was calculated relative to the reference body (microscrew) placed adjacent to the implant. Micromovement observed varied with the force applied. Lateral force of 5 N resulted in a mean displacement of 39 microm; for 30 N, the mean displacement was 157 microm. Bone type also influenced the amount of movement. Contact endoscopy represents a new method for direct observation of implant movement relative to the bone surface in vitro. In combination with support immersion technique, contact endoscopy could be used as an office procedure to evaluate intraoperatively implant stability during functional loading.