A Computerized Tomographic Data Analysis System to Evaluate the Dental Implant Surface Roughness

AbstractDental implants have been progressively used in the recent years to support and retain dental prosthesis. Implant surface roughness has been suggested as a crucial factor in implant osseointegration and long term survival of the implant and prosthesis, where a key factor for the success or failure of dental implants is the manner in which stresses are transferred to surrounding bone. In this study completely edentulous patients were rehabilitated by implant retained over denture in which two implant systems with different surface roughness were used. Peri implant bone density in Hounsfield Units (HU) was evaluated by analyze Computerized Tomographic (CT) images to judge the behavior of an implant system under functional loading, where DICOM raw data was imported into the analysis proposed system to correlate the bone density regarding to the HU values. Results are compared with clinical readings and previous findings, which it showed that there is a difference in peri implant bone density around regularly patterned and randomly patterned implant surfaces

Estudo comparativo de protocolos tomográficos na aquisição das imagens para confecção de modelos de prototipagem

Convenio realizado entre la Universidade Federal do Rio Grande do Sul y la Universidad de la República Oriental del Uruguay en el marco del Programa de Post-graduación en Odontología.A especialidade de Prótese Buco-Maxilo-Facial é responsável por reconstruções complexas da face e do crânio. Entretanto, com a utilização de impressões convencionais, é difícil se alcançar uma adequada adaptação clínica para a reabilitação do paciente. Assim, algumas vêzes, faz-se necessária a obtenção de modelos tridimensionais (3D) que reproduzam a realidade clínica. O objetivo deste estudo é comparar os protótipos obtidos com diferentes protocolos de aquisição de imagem provenientes de distintos aparelhos de tomografia computadorizada com relação à rugosidade superficial, área reconstruída e dose de exposição gerada, procurando estabelecer o mais adequado para a confecção de protótipos de crânio. Para isso, nove protótipos de um fragmento craniofacial seco foram confeccionados. A comparação entre os protótipos quanto à lisura superficial e à área reconstruída foi realizada por meio da Análise de Variância (ANOVA). Nos casos em que a avaliação indicou diferença significativa, foi aplicado como complemento o Teste de Comparações Múltiplas de Tukey. O nível de significância adotado foi de 5%. Em relação à análise de rugosidade as diferenças encontradas não demonstraram correlação com a área reconstruída. Já em relação aos diferentes protocolos, diferenças significativas foram observadas nos protótipos com respeito à área reconstruída e dose de radiação gerada. Pode-se concluir, frente aos resultados encontrados, que as imagens geradas pelos tomógrafos de feixe cônico e feixe em leque, utilizando os protocolos com as resoluções máximas estudadas, estão indicadas para a confecção de protótipos. Contudo, o que deve nortear a seleção do melhor protocolo tomográfico deve ser o propósito da indicação clínica correlacionado com o princípio ALARA (As Low As Reasonably Achievable).Oral-maxillo-facial prosthodontics is the study of complex face and skull reconstructions. In view of the insufficient degree of adjustment of conventional impression to enable proper clinical rehabilitation, among other reasons, practitioners increasingly resort to 3D models that accurately reproduce the clinical reality. The aim of this study is to determine the optimal selection of imaging device and protocol for use in skull prototyping. The surface roughness and reconstructed area of nine prototypes obtained from a dried craniofacial specimen using different image acquisition protocols and CT devices were measured, in addition to measurements of the radiation dose potentially received by the patient. ANOVA of the surface roughness, reconstructed area and radiation dose data enabled statistical comparisons among the prototypes. Where significant differences were found, Tukey’s multiple-comparison test was conducted, using a significance level of 5%. No correlation was found between surface roughness and reconstructed area. However, significant differences in reconstructed area and radiation dose were found among the different protocols. These results support the use of images generated by CBCT or fan beam CT for the construction of prototypes, using the protocols with the highest resolution. Nevertheless, the selection of the most appropriate TC protocol should be based on the particular clinical indication along with the ALARA (as low as reasonably achievable) principle

Combined microcomputed tomography, biomechanical and histomorphometric analysis of the peri-implant bone: A pilot study in minipig model

Objectives To present a practical approach that combines biomechanical tests, microcomputed tomography (μCT) and histomorphometry, providing quantitative results on bone structure and mechanical properties in a minipig model, in order to investigate the specific response to an innovative dental biomaterial. Methods Titanium implants with innovative three-dimensional scaffolds were inserted in the tibias of 4 minipigs. Primary stability and osseointegration were investigated by means of insertion torque (IT) values, resonance frequency analysis (RFA), bone-to-implant contact (BIC), bone mineral density (BMD) and stereological measures of trabecular bone. Results A significant positive correlation was found between IT and RFA (r = 0.980, p = 0.0001). BMD at the implant sites was 18% less than the reference values (p = 0.0156). Peri-implant Tb.Th was 50% higher, while Tb.N was 50% lower than the reference zone (p < 0.003) and they were negatively correlated (r = -0.897, p = 0.006). Significance μCT increases evaluation throughput and offers the possibility for qualitative three-dimensional recording of the bone-implant system as well as for non-destructive evaluation of bone architecture and mineral density, in combination with conventional analysis methods. The proposed multimodal approach allows to improve accuracy and reproducibility for peri-implant bone measurements and could support future investigations

Deflection changes of mini implants at different bone densities: An In vitro study

AIM OF THE STUDY: This study was performed to radiographically evaluate the deflection changes of titanium alloy self-drilling mini implants from the intended path that occurs during placement in varying bone densities. METHOD: 63 titanium alloy self-drilling mini implants of the lengths 6mm, 8mm, and 10mm with constant diameter of 1.3mm were used. Three homogenous Solid rigid polyurethane foam (saw bone) with bone densities of 20pcf, 30pcf, and 40pcf were used in this study to simulate anatomic sites for clinical insertion of mini implants in maxilla and mandible. Total of 63 bone blocks, 27 in each bone X 2 were used. 7 mini implants of each length in all the densities were tested for study. The implants were inserted perpendicularly into artificial bone block held in a custom made stand. One mini implant was inserted per bone block. The bone blocks were then radiographically exposed and the deviation of the long axis of the implant from a true vertical line drawn through the centre of entry of the implant into cortical bone was measured. RESULTS: There was a decrease in deflection of the mini implant with increase in density. On the other hand, increase in length resulted in increase in the amount of deflection. CONCLUSION: Knowledge of bone density in the maxilla and mandible will correlate many of the clinical findings as well as allow the clinician to plan the anchorage strategies and placement of implants with necessary precautions accordingly. Longer mini implants can be used in less dense bone as in maxilla, whereas shorter mini implants can be used in high dense bone as in mandible to increase the stability and success rate of implants. Bone density and implant length play a role in deflection of mini implant from its intended path of insertion. There by evaluation of the relationship of the insertion pathway with the adjacent structures is needed to reduce the iatrogenic damage

Peri-implantitis experimental. Etiología y tratamiento

Tesis inédita de la Universidad Complutense de Madrid, Facultad de Odontología, leída el 12/02/2021. Tesis formato europeo (compendio de artículos)Peri-implantitis is a chronic inflammatory disease caused by bacteria resulting in peri-implant tissue inflammation and bone loss. Several factors such as the implantabutment connection or the implant surface are known to be closely related to the maintenance of peri-implant bone levels. Different implant to abutment configurations, such as platform switching have shown to facilitate bone stability by providing extra space for the peri-implant soft tissue seal. However, its influence on the initiation and progression of peri-implantitis remains unclear. Similarly, innovations in the chemical composition of the implant surface have shown a stronger bond between the implant and the surrounding bone. However, whether this covalent bonding may as well provide increased protection against bacterial challenge and hence, a lesser incidence of periimplantitis, is still unknown. With current regenerative surgical interventions, re-osseointegration of a previously contaminated implant surface has been shown to be possible, although its predictability has not been demonstrated. Growth factors such as bone morphogenetic proteins have demonstrated osteogenic activity when used in bone regenerative interventions, mainly when used in sinus lifting and lateral bone augmentation procedures. However, studies using BMP-2 aiming for re-osseointegration of periimplantitis bone defects have showed conflicting results. Objectives: The objectives of this series of investigations were: a) to evaluate the degree of bone regeneration and re-osseointegration when combining a xenogeneic bone replacement graft plus rhBMP-2 and a collagen membrane in ligature induced periimplantitis osseous defects in dogs (study 1); b) to evaluate the rate of bone loss progression during experimentally induced peri-implantitis using two different implantabutment connections in implants with identical surface topography (study 2); c) to evaluate the influence of modifying the implant surface by adding a monolayer of multiphosphonate molecules on de-novo bone formation and osseointegration (study 3); and d) to evaluate the susceptibility to bone loss of a novel multi-phosphonate implant surface treatment during experimental peri-implantitis (study 4)...La peri-implantitis es una enfermedad inflamatoria crónica causada fundamentalmente por bacterias, que produce inflamación y pérdida de hueso periimplantaria. Diferentes factores como el tipo de conexión entre el pilar y el implante o las características de superficie influyen directamente en el mantenimiento de los niveles óseos peri-implantarios. Un tipo de conexión implante-pilar conocida como “cambio de plataforma” ha demostrado mayor estabilidad del hueso peri-implantario gracias al espacio extra que proporciona a los tejidos blandos y su consiguiente sellado mucoso alrededor del implante. Sin embargo, el papel que juega en el inicio y progresión de la peri-implantitis sigue sin estar claro. De forma similar, innovaciones en la composición química de la superficie implantaria han demostrado proporcionar una unión más íntima entre el implante y el hueso. Sin embargo, el hecho de que dicho incremento en el contacto entre el hueso y el implante proporcione mayor protección frente a la periimplantitis sigue siendo una incógnita. Mediante los procedimientos de cirugía regenerativa actuales es posible conseguir re-oseointegración de una superficie previamente contaminada, sin embargo, dicha reoseointegración sigue siendo impredecible y difícil de obtener de forma completa. En este sentido, factores de crecimiento como las proteínas morfogenéticas han demostrado incrementar la capacidad osteogénica de procedimientos como la elevación de seno maxilar o el aumento horizontal de cresta. Sin embargo, los estudios que evalúan la capacidad de la BMP-2 en el incremento de la reoseointegración han arrojado resultados contradictorios. Objetivos: Los objetivos de esta serie de estudios fueron: a) evaluar el grado de regeneración ósea y re-oseointegración mediante la utilización de una combinación de un sustituto óseo xenogénico junto a rhBMP-2 y una membrana de colágeno en defectos óseos producidos tras peri-implantitis experimental (estudio 1); b) evaluar la pérdida ósea a lo largo del proceso de peri-implantitis experimental usando dos tipos de conexión implante-pilar diferentes en implantes con la misma superficie (estudio 2); 3) evaluar la influencia de la modificación de la superficie peri-implantaria mediante la adición de una monocapa de fosfonatos en la oseointegración (estudio 3); y 4) evaluar la susceptibilidad de esta nueva superficie en el desarrollo de la peri-implantitis experimental (estudio 4)...Fac. de OdontologíaTRUEunpu

A brief review on micro-implants and their use in orthodontics and dentofacial orthopaedics

The aim of this study was to review the literature and evaluate the failure rates and factors that affect the stability and success of temporary anchorage devices (TADs) used as orthodontic anchorage. Data was collected from electronic databases: MEDLINE database and Google Scholar. Four combinations of term were used as keywords: \u201cmicro-implant\u201d, \u201cmini-implant\u201d, \u201cmini-screw\u201d, and \u201corthodontics\u201d. The following selection criteria were used to select appropriate articles: articles on implants and screws used as orthodontic anchorage, published in English, with both prospective and retrospective clinical and experimental investigations. The search provided 209 abstracts about TADs used as anchorage. After reading and applying the selection criteria, 66 articles were included in the study. The data obtained were divided into two topics: which factors affected TAD success rate and to what degree and in how many articles they were quoted. Clinical factors were divided into three main groups: patient-related, implant related, and management-related factors. Although all articles included in this meta-analysis reported success rates of greater than 80 percent, the factors determining success rates were inconsistent between the studies analyzed and this made conclusions difficult

Design of a precision compactor for use in guided bone regeneration in the area of oral surgery

During the processes of guided bone regeneration in the maxillary bones, which aim to recover or preserve support tissue for the placement of implants on which dental prostheses are retained, the use of various particulate graft biomaterials from different sources (animal or synthetic) is standardized. At present, the pressure of compaction of this material in the recipient bone is manual, dependent on the clinician, although there is some scientific evidence on the effects of different compressive forces on angiogenesis and prognosis of the regeneration of the grafted areas. The aim of the present study is to design, calibrate and verify in vitro a compaction instrument for clinical use, which allows a controlled and precise compaction pressure of the particulate graft biomaterial and standardize the procedure. The designed instrument is a precision compactor of adequate size for proper intra and extraoral clinical manageability and manufactured in a sterilizable material by autoclaving. The range of compression that allows (0 -1, 82 Newton), is within the forces that are commonly applied in surgery and that have been determined by a specific test on 8 oral surgeons. Instrument calibration has been performed by an independent accredited company. The testing of the instrument was carried out by an in vitro test where the biomaterial was compacted at different forces (0, 80 and 1, 82 Newton) and was observed by a computerized micro-tomography that when increasing the compression force, decreased the space between particles provided for the migration and proliferation of new blood vessels and cells. Durante los procedimientos de regeneración ósea guiada en los huesos maxilares, que tienen como objetivo recuperar o preservar tejido de soporte para la colocación de implantes sobre los que se retienen las prótesis dentales, está estandarizado el uso de diversos biomateriales de injerto particulado de diferente procedencia (animal o sintético). En la actualidad la presión de compactación de dicho material en el hueso receptor es manual, clínico dependiente, pese a que existe cierta evidencia científica sobre los efectos de las diferentes fuerzas de compresión en la angiogénesis y pronóstico de la regeneración de las zonas injertadas. El objetivo del presente estudio es el de diseñar, calibrar y comprobar in vitro un instrumento de compactación para uso clínico, que permita una presión de compactación controlada y precisa del biomaterial de injerto particulado y estandarizar el procedimiento. El instrumento diseñado es un compactador de precisión de tamaño adecuado para una correcta manejabilidad clínica intra y extraoral y fabricado en un material esterilizable por autoclavado. El rango de compresión que permite (0 – 1, 82 Newton), está dentro de las fuerzas que se aplican comúnmente en cirugía y que se han determinado mediante una prueba específica sobre 8 cirujanos orales. La calibración del instrumento se ha realizado por una empresa acreditada independiente. La comprobación del instrumento se ha realizado mediante un ensayo in vitro donde se compactó el biomaterial a diferentes fuerzas (0, 80 y 1, 82 Newton) y se observó mediante micro-tomografía computerizada que al aumentar la fuerza de compresión disminuía el espacio entre partículas provisto para la migración y proliferación de los nuevos vasos sanguíneos y células