Felipe J. Fernández-González

Recombinant osteoprotegerin effects during orthodontic movement in a rat model.

BACKGROUND AND OBJECTIVES Anchorage is one of the most challenging sides in orthodontics. The use of biological modulators that inhibit osteoclasts could be a solution to address these problems and provide new adjunctive approaches. The aim of this study was to assess the effectiveness of recombinant osteoprotegerin fusion protein (OPG-Fc) in orthodontic anchorage. MATERIALS AND METHODS Two groups of male Sprague-Dawley rats were utilized. The animals in the experimental group received twice-weekly injections with high dose of OPG-Fc (5.0mg/kg) in mesial and distal mucosa of the first molars, and those in the control group received no drugs. Right first maxillary molars were mesialized using a calibrated nickel-titanium spring connected to an anterior mini-screw. Tooth movement was measured by two blinded observers using scanned and magnified stone casts. Receptor activator of nuclear factor κB (RANK), run-related transcription factor 2 (Runx2), type I collagen, vimentin, matrix metalloproteinases 2 and 9, S100 protein and the putative mechanoproteins acid-sensing ion channel (ASIC2) and transient receptor potential vainilloid 4 (TRPV4) were evaluated using immunohistochemistry. RESULTS OPG-Fc group showed an important decreased in mesial molar movement with only 52%, 31%, and 22% of the total mesial molar movement compared with control group at Days 7, 14, and 21, respectively (P < 0.001). RANK ligand and Runx2 positive cells were severely reduced after OPG-Fc treatment. Periodontal ligament architecture, cell arrangement, and immunohistochemical patter for vimentin, type I collagen and the mechanoproteins TRPV4 and ASIC2 were altered by tooth movement and all these parameters altered by the applied treatment. CONCLUSIONS OPG-Fc effectively inhibits osteoclastogenesis resulting in improved bone quantity and orthodontic anchorage. Based on present results, OPG-Fc could have clinical utility in preventing undesired tooth movements.

Osteotome sinus floor elevation without grafting material: results of a 2-year prospective study

Objectives: The aim of this prospective clinical trial was to evaluate the success implant rates during 24 months using OSFE procedure without grafting materials. Study design: 42 adult patients (22 female, 15 male) were selected according to Nedir et al´s inclusion criteria of which 5 patients were excluded, due to periapical pathology in adjacent teeth (n=3) and treatment with bisphosphonates (n=2). 37 patients aged 31-68 years were selected. Smokers were divided in two groups depending on the number of cigarettes consumed per day (a) 0-10, (b) 11-20. One patient was excluded because he was lost to follow-up at 24 months A total of 36 threaded implants were placed, ∅4,1mm Straumann® (Straumann AG, Waldenburg, Switzerland) and ∅3,5mm Klockner® (Klockner Implant System, Barcelona, Spain). The most used implant diameter was 4,1 mm (n=29), followed by 3,5 mm (n=7), and length used was 10 mm (n=32) and 8 mm (n=4). Initial RBH ranged from 4 mm to 9 mm. All statistical data were processed using the program R 3.0.2 for windows. Results: A total of 36 threaded implants were placed. Residual bone height (RBH) at implant placement averaged 7,4 ± 0,4 mm. Mean bone gain was 1,8 ± 0,3 mm. Four implants showed a bone gain exceeding 3 mm. Mean implant protrusion length into the sinus amounted to 2.1 ± 0,3 mm. Regarding the relationship between smoking and periodontal probes, no statistically significant differences were found (P=0,25), neither in relation to the number of threads that the implants showed (P=0,29) or bone gain (P=0,79). After 24 months the implant success rate was 91,6%. Conclusions: Implant rehabilitation of edentulous atrophied posterior maxilla can be safely performed and simplified using the OSFE technique without grafting with reliable long-term results. Key words:Crestal bone loss, dental implants, internal sinus lift, no grafting, osteotome sinus elevation, grafting, sinus floor elevation.

Fracture Resistance of Monolithic High Translucency Zirconia Implant-Supported Crowns.

Aim:To evaluate the resistance to axial forces of screw-retained monolithic high translucency zirconia (mHTZr) crowns compared with high translucency zirconia + feldspathic ceramic (HTZrC) crowns, low translucency zirconia + feldspathic ceramic (LTZrC) crowns, and metal-ceramic (MC) crowns, and also to observe the different fracture patterns between all groups. Methods:Twenty-four crowns were fabricated (6 of each group) and loaded until failure, using a testing machine with a 5.0-kN load cell. Results:Mean fracture results varied between 1092.7 N (LTZrC group) and 3439.7 N (mHTZr group). No statistically significant differences were found between the HTZrC, LTZrC, and MC groups. However, statistically significant differences (P < 0.05) were found between mHTZr and the other 3 groups. In the MC group, only chipping of the ceramic veneering occurred. In the mHTZr group, when fracturing occurred, it was of the whole structure. Finally, the LTZrC and HTZrC groups suffered both chipping and core fractures. Conclusion:High translucency monolithic zirconia implant–supported crowns proved to be the toughest group studied when an axial force was applied. Fracture patterns varied between different materials, chipping being the most common occurrence.

Biomechanical Consequences of the Elastic Properties of Dental Implant Alloys on the Supporting Bone: Finite Element Analysis.

The objective of the present study is to evaluate how the elastic properties of the fabrication material of dental implants influence peri-implant bone load transfer in terms of the magnitude and distribution of stress and deformation. A three-dimensional (3D) finite element analysis was performed; the model used was a section of mandibular bone with a single implant containing a cemented ceramic-metal crown on a titanium abutment. The following three alloys were compared: rigid (Y-TZP), conventional (Ti-6Al-4V), and hyperelastic (Ti-Nb-Zr). A 150-N static load was tested on the central fossa at 6° relative to the axial axis of the implant. The results showed no differences in the distribution of stress and deformation of the bone for any of the three types of alloys studied, mainly being concentrated at the peri-implant cortical layer. However, there were differences found in the magnitude of the stress transferred to the supporting bone, with the most rigid alloy (Y-TZP) transferring the least stress and deformation to cortical bone. We conclude that there is an effect of the fabrication material of dental implants on the magnitude of the stress and deformation transferred to peri-implant bone.

Biomechanical evaluation of oversized drilling technique on primary implant stability measured by insertion torque and resonance frequency analysis

Background This study evaluated the influence of implant site preparation depth on primary stability measured by insertion torque and resonance frequency analysis (RFA). Material and Methods Thirty-two implant sites were prepared in eight veal rib blocks. Sixteen sites were prepared using the conventional drilling sequence recommended by the manufacturer to a working depth of 10mm. The remaining 16 sites were prepared using an oversize drilling technique (overpreparation) to a working depth of 12mm. Bone density was determined using cone beam computerized tomography (CBCT). The implants were placed and primary stability was measured by two methods: insertion torque (Ncm), and RFA (implant stability quotient [ISQ]). Results The highest torque values were achieved by the conventional drilling technique (10mm). The ANOVA test confirmed that there was a significant correlation between torque and drilling depth (p<0.05). However, no statistically significant differences were obtained between ISQ values at 10 or 12 mm drilling depths (p>0.05) at either measurement direction (cortical and medullar). No statistical relation between torque and ISQ values was identified, or between bone density and primary stability (p >0.05). Conclusions Vertical overpreparation of the implant bed will obtain lower insertion torque values, but does not produce statistically significant differences in ISQ values. Key words:Implant stability quotient, overdrilling, primary stability, resonance frequency analysis, torque.

Análisis Comparativo de la Repetibilidad y Reproductibilidad de Dos Métodos de Medición de la Dimensión Vertical en Rehabilitación Oral: Una Revisión Sistemática

El objetivo de este estudio establecer si el metodo de evaluacion de la dimension vertical mediante cefalometria y el convencional con rodillos de articulacion, consiguen resultados sin diferencias estadisticamente significativas. Realizacion de una revision sistematica conforme a la metodologia PICO del Centro de Medicina Basada en la Evidencia de Oxford. Se formula una pregunta dirigida al objetivo fijado y se elabora una estrategia de busqueda empleando MeSH key words especificos derivados de la pregunta en la base de datos PubMed hasta 2015 y libros de rehabilitacion oral. Se consultan un total de 833 articulos por titulo, siendo 26 revisados a texto completo. Se analizan trabajos sobre distintos metodos de determinacion de la dimension vertical, haciendo especial hincapie en los basados en metodos cefalometricos. Finalmente 9 articulos cumplen los criterios de inclusion y se realiza una evaluacion critica del nivel de evidencia. No se ha encontrado suficiente evidencia cientifica que demuestre la repetibilidad de ambos metodos. Es necesario realizar estudios controlados y aleatorizados que comparen ambos metodos para determinar si son repetibles y reproducibles y obtienen resultados sin diferencias estadisticamente significativas.

Efficacy of Selective Grinding Guided by an Occlusal Splint in Management of Myofascial Pain: A Prospective Clinical Trial

Background: For patients whose centric relation (CR) has not been considered at the start and during treatment, the task of achieving an occlusal scheme that works together with the temporomandibular joint, the muscles, and the structures of the stomatognathic apparatus becomes a major concern. Objective: This study aims to describe a reproducible, predictable and to date unreported procedure of selective grinding guided by an occlusal splint and to analyze condylar position (CP) based on the skeletal pattern. Methods: A total of 72 symptomatic patients (38 females and 34 males) were classified into three groups: hyperdivergent, intermediate and hypodivergent. CP was quantified by mounted casts on a measures condyle displacement (MCD) device. Helkimo index was also performed in order to assess the severity of the temporomandibular joint (TMJ) disorders attending to clinical dysfunction, occlusal state and anamnestic dysfunction. Once the stability had been obtained, the splint was progressively reduced until the maximum intercuspation (MIC) was achieved. Results: The vertical displacement was found to be significantly different between the hyperdivergent and other two groups (p<0.01). Comparisons of MCD analysis before and after the selective grinding procedure identified a statistically significant difference in the horizontal and vertical CP (p<0.01) between the different groups whereas the Helkimo Index showed a clear improvement of TMJ disorders. Conclusion: All facial types, specially the hyperdivergent face type, showed a reduction in condylar displacement (CD) and less craniomandibular symptoms using this procedure, making it an excellent technique for clinicians.

Accuracy of Resonance Frequency Analysis by Third Generation Osstell

El analisis de frecuencia de resonancia (AFR) por Osstell® se utiliza en la evaluacion de la estabilidad primaria y secundaria del implante. El objetivo del presente estudio fue establecer la precision del AFR mediante Osstell©, como metodo de prueba empleado en la determinacion de la estabilidad implantaria. Se realizo un estudio experimental in vitro, en el que se colocaron implantes en una costilla de vaca y compararon diferentes mediciones del coeficiente de estabilidad del implante (ISQ) obtenidas sobre estos implantes con un mismo transductor SmartPeg (repetibilidad) o con diferentes SmartPegs (reproductibilidad). El analisis estadistico de los datos mostro una elevada correlacion de los ISQ obtenidos en ambos ensayos, lo cual sugiere una reproductibilidad y repetibilidad elevada del analisis mediante Osstell.

Experimental evidence of pharmacological management of anchorage in Orthodontics: A systematic review

Introduction: Orthodontic anchorage is one of the most challenging aspects of Orthodontics. Preventing undesired movement of teeth could result in safer and less complicated orthodontic treatment. Recently, several reviews have been published about the effects of different molecules on bone physiology and the clinical side effects in Orthodontics. However, the effects of local application of these substances on the rate of orthodontic tooth movement have not been assessed. Objectives: The aim of this research was to analyze the scientific evidence published in the literature about the effects of different molecules on orthodontic anchorage. Methods: The literature was systematically reviewed using PubMed/Medline, Scopus and Cochrane databases from 2000 up to July 31st, 2014. Articles were independently selected by two different researchers based on previously established inclusion and exclusion criteria, with a concordance Kappa index of 0.86. The methodological quality of the reviewed papers was performed. Results: Search strategy identified 270 articles. Twenty-five of them were selected after application of inclusion/exclusion criteria, and only 11 qualified for final analysis. Molecules involved in orthodontic anchorage were divided into three main groups: osteoprotegerin (OPG), bisphosphonates (BPs) and other molecules (OMs). Conclusions: Different drugs are able to alter the bone remodeling cycle, influencing osteoclast function and, therefore, tooth movement. Thus, they could be used in order to provide maximal anchorage while preventing undesired movements. OPG was found the most effective molecule in blocking the action of osteoclasts, thereby reducing undesired movements.