Investigation to Predict Primary Implant Stability Using Frictional Resistance Torque of Tap Drilling.

Objectives: The purpose of this experimental study was to investigate the correlation between the frictional resistance torque of tap drilling prior to implant placement and the primary stability after implant placement. Material and Methods: Solid rigid polyurethane bone blocks of four different densities were used in this study. A computerized surgical implant motor device was utilized to measure the frictional resistance torque of tap drilling. After the tap torque was measured, the dental implants were inserted at the prepared sites. During the implantation, the insertion torque was recorded, and resonance frequency analysis was performed, the value of which was calculated as the implant stability quotient. Thereafter, the correlation between the tap torque and the primary stability of the implant was evaluated and compared with the standard drilling protocol. Results: A significant positive correlation was found between the tap torque and insertion torque (Pearson's r = 0.88, P < 0.0001). Similarly, there was a positive correlation between the tap torque and implant stability quotient (Pearson's r = 0.69, P < 0.0001). Conclusions: These results suggest that measurement of the frictional resistance torque of tap drilling prior to implant placement could provide helpful information for implant primary stability.

In vitro mechanical evaluation of spinal fixation rod connectors / Avaliação mecânica in vitro de conectores das hastes de fixação vertebral / Evaluación mecánica in vitro de conectores de varillas de fijación de la columna

ABSTRACT Objective Evaluate and compare the mechanical resistance and the fatigue behavior associated with the use of three different modalities of vertebral fixation system rod connectors through in vitro pre-clinical mechanical tests developed specifically for this application (linear, lateral with square connector and lateral with oblique connector). Methods Cobalt chromium rods 5.5 mm in diameter were used and coupled with three types of connectors: a) side rod with oblique connector, b) side rod with square connector, and c) rod and linear connectors. Quasi-static mechanical four-point bending and fatigue tests were performed. The variables measured were (I) the bending moment at the yield limit, (II) the displacement at the yield limit, (III) the rigidity of the system in flexion and (IV) the number of cycles until system failure. Results The linear system presented the greatest force and the greatest moment at the yield limit, as well as the greatest stiffness equivalent to bending. All specimens with square and oblique connectors endured 2.5 million cycles in the minimum and maximum conditions of applied moment. The specimens with linear connector endured 2.5 million cycles with fractions of 40.14% of the bending moment at the yield limit, but failed with levels of 60.17% and 80.27%. Conclusions Systems with linear connectors showed greater mechanical resistance when compared to systems with square and oblique connectors. All systems supported cyclic loads that mimic in vivo demands. Level of evidence V; In vitro research.

RESUMO Objetivo Avaliar e comparar a resistência mecânica e o comportamento em fadiga associados ao uso de três modalidades distintas de conectores de hastes do sistema de fixação vertebral por meio de ensaios mecânicos pré-clínicos in vitro desenvolvidos especificamente para essa aplicação (linear, lateral com conector quadrado e lateral com conector oblíquo). Métodos Foram usadas hastes de Cromo-cobalto de 5,5 mm de diâmetro acopladas a três modalidades de conectores: a) haste lateral com conector oblíquo, b) haste lateral com conector quadrado e c) haste e conector lineares. Foram realizados ensaios mecânicos quase-estáticos e de fadiga sob flexão em quatro pontos. As variáveis medidas foram (I) o momento fletor no limite de escoamento, (II) o deslocamento no limite de escoamento e (III) a rigidez do sistema em flexão e (IV) número de ciclos até a falha do sistema. Resultados O sistema linear apresentou a maior força e o maior momento no limite de escoamento, bem como maior rigidez equivalente à flexão. Todos os corpos de prova com conectores quadrados e oblíquos suportaram 2,5 milhões de ciclos nas condições mínimas e máximas de momento aplicado. Os corpos de prova com conector linear suportaram 2,5 milhões de ciclos com frações de 40,14% do momento fletor no limite do escoamento, porém falharam com níveis de 60,17% e 80,27%. Conclusões Os sistemas com conectores lineares apresentaram maior resistência mecânica quando comparados aos sistemas com conectores quadrados e oblíquos. Todos os sistemas suportaram carregamentos cíclicos que mimetizam as solicitações in vivo. Nível de evidencia V; Pesquisa in vitro.

RESUMEN Objetivo Evaluar y comparar la resistencia mecánica y el comportamiento de fatiga asociado al uso de tres modalidades distintas de conectores de varilla del sistema de fijación vertebral a través de ensayos mecánicos preclínicos in vitro desarrollados específicamente para esta aplicación (lineal, lateral con conector cuadrado y lateral con conector oblicuo). Métodos Se utilizaron varillas de cromo-cobalto de 5,5 mm de diámetro acopladas a tres tipos de conectores: a) varilla lateral con conector oblicuo, b) varilla lateral con conector cuadrado y c) varilla y conector lineales. Se realizaron ensayos mecánicos y de fatiga cuasi-estáticos y ensayos por flexión de cuatro puntos. Las variables medidas fueron (I) el momento flector en el límite elástico, (II) el desplazamiento en el límite elástico y (III) la rigidez del sistema en flexión y (IV) el número de ciclos hasta la falla del sistema. Resultados El sistema lineal presentó la mayor fuerza y el mayor momento en el límite elástico, así como la mayor rigidez equivalente a la flexión. Todas las probetas con conectores cuadrados y oblicuos soportaron 2,5 millones de ciclos en las condiciones mínimas y máximas de momento aplicado. Las probetas con conector lineal soportaron 2,5 millones de ciclos con fracciones del 40,14% del momento flector en el límite elástico, pero fallaron con niveles de 60,17% y 80,27%. Conclusiones Los sistemas con conectores lineales mostraron mayor resistencia mecánica en comparación con los sistemas con conectores cuadrados y oblicuos. Todos los sistemas admitían cargas cíclicas que imitan las solicitudes in vivo. Nivel de Evidencia V; Investigación in vitro.

Avaliação da absorção de proteínas em ratas submetidas à colocação de mini-implantes de silicone nanotexturizados e revestidos pela espuma de poliuretano / Evaluation of protein adsorption in rats submitted to nanotextured and polyurethane foam-coated silicone mini-implants

RESUMO Introdução: O controle da absorção de proteínas é necessário para a definição das propriedades dos biomateriais e de seus usos específicos. O plasma sanguíneo contém diversas proteínas diferentes, dentre elas o fibrinogênio, que apresenta importante papel na adesão celular e nos resultados de biocompatibilidade em implantes. Os objetivos deste estudo foram avaliar laboratorialmente as ratas submetidas à colocação de mini-implantes de silicone nanotexturizados e revestidos por espuma de poliuretano a partir da aferição do fibrinogênio sérico e mensuração da proteína plasmática. Métodos: Foram utilizadas 60 ratas albinas, divididas em dois grupos de 30 animais para cada tipo de mini-implante de silicone (nanotexturizado e espuma de poliuretano) e subdivididas em 3 subgrupos, conforme o tempo de eutanásia dos animais (30, 60 e 90 dias). Os mini-implantes foram inseridos no dorso dos animais abaixo do Panniculus carnosus. No momento das eutanásias, amostras de sangue foram obtidas por punção cardíaca. Utilizou-se a técnica de precipitação térmica para determinação das proteínas plasmáticas total e sérica, e o valor do fibrinogênio foi obtido mediante a diferença entre estas duas últimas. Resultados: Quando comparados os grupos entre si, observou-se que o grupo nanotexturizado apresentou uma maior quantidade de fibrinogênio e da proteína plasmática no subgrupo de 90 dias, com significância estatística (p=0,004). Ao comparar os subgrupos entre si, em ambos os grupos, evidenciou-se uma diferença significativa (p<0,001). Conclusão: Os mini-implantes nanotexturizados mostraram uma menor absorção de proteínas em relação aos implantes revestidos pela espuma de poliuretano, no subgrupo de 90 dias.

ABSTRACT Introduction: The control of protein absorption is necessary to define biomaterials' properties and their specific uses. Blood plasma contains several different proteins, including fibrinogen, which plays an important role in cell adhesion and biocompatibility results in implants. This study's objectives were to evaluate in the laboratory rats subjected to the placement of nano-textured silicone mini-implants and polyurethane foam-coated mini-implants based on the measurement of serum fibrinogen and plasma proteins. Methods: Sixty albino rats were used, divided into two groups of 30 animals for each type of silicone mini-implant (nanotextured and polyurethane foam) and subdivided into three subgroups, according to the animals' euthanasia time (30, 60 and 90 days). The mini-implants were inserted in the animals' backs below the Panniculus carnosus. At the time of euthanasia, blood samples were obtained by cardiac puncture. The thermal precipitation technique was used to determine total and serum plasma proteins, and the difference between the latter two obtained the fibrinogen value. Results: When the groups were compared, it was observed that the nanotextured group presented a higher amount of fibrinogen and plasma protein in the 90-day subgroup, with statistical significance (p=0.004). When comparing the subgroups among themselves, a significant difference was evidenced (p<0.001). Conclusion: The nanotextured mini-implants showed a lower protein absorption concerning polyurethane foam-coated implants in the 90-day subgroup.

Manganese dioxide coating reduces bacterial adhesion and infection in silicon implants in animal model.

PURPOSE: To propose a new coating to silicone implants using Manganese dioxide. We present bacterial adhesion and proliferation when implants are challenged with Escherichia coli. METHODS: Coated and control silicon implants were placed in two independent subcutaneous pouches in the dorsum of Wistar rats. After skin closure, 0.5 ml of E. coli solution was injected in each incision. The animals were euthanized at 7 and 28 days. Extracted material was cultured and analyzed by confocal microscopy. RESULTS: At 1 week, uncoated implants had a 17-fold higher infection rate (p < 0.001). Coated samples showed a mean bacterial count of 28,700 CFU/ml, while the control ones 503,000 CFU/ml, with a significant mean difference of 474,300 CFU/ml (95% CI 165,900-782,600). At 4 weeks, the mean bacterial growth in coated group was 7600; while in control one was 53,890. The mean difference between groups was 46,200 (95% CI 21,100-71,400). Confocal microscopy presented the percentage of implant's surface with attached bacteria: at 7 days, coated implants had 6.85% and controls 10.9% and the difference was not significant (p =0.32). At 4 weeks, the coated group showed 0.98% of the surface with attached bacteria, while control group showed 7.64%, which resulted in a significant 11-fold difference (p = 0.004). CONCLUSIONS: Manganese dioxide coating inhibits bacterial proliferation and adhesion in subcutaneous silicon implants in an animal model. These findings can be useful to improve development of biomaterials.

Estudo experimental do uso do vidro bioativo com implantes imediatos em cirurgia para levantamento da membrana sinusal: análises histológica, histomorfométrica e imunoistoquímica / Use of bioactive glass with immediate implants in surgery to lift the sinus membrane: histological, histomorphometric and immunohistochemical study

A proposta deste estudo foi avaliar o processo de regeneração óssea com o uso do biomaterial Biogran®, um vidro bioativo, como uma opção de substituto ósseo para técnicas de enxerto em levantamento do assoalho do seio maxilar através de análises histológica e histomorfométrica. Para tal, 24 coelhos da raça Nova Zelândia foram submetidos ao procedimento de levantamento do seio maxilar bilateralmente, sendo divididos em dois grupos: grupo coágulo implante (GCI), no qual foi realizado o levantamento do seio maxilar, seguindo implante imediato, sem enxerto; e o grupo biovidro implante (GBI), no qual foi realizado o levantamento do seio maxilar, preenchimento com Biogran® e instalação de implante imediata. Os animais foram submetidos à eutanásia aos 7, 15 e 40 dias. A análise histológica mostrou no grupo GCI uma formação de tecido ósseo gradual, sendo maior aos 40 dias, com característica lamelar. Porém, não apresentava diferença estatística entre os períodos de 15 e 40 dias de eutanásia (p=0,210). O grupo GBI revelou uma formação de tecido ósseo mais tardia, com maior quantidade aos 40 dias, com reabsorção lenta e progressiva dos grânulos do biomaterial e sinais indicativos de atividade osteoblástica. Este grupo mostrou diferença estatística entre os períodos de 7 e 15 dias quando comparados aos 40 dias (p<0,05). Na análise intergrupos, não houve diferença estatisticamente significante aos 7 e aos 40 dias, mas sim, aos 15 dias. Dessa forma, pode-se concluir que o Biogran® é um biomaterial com propriedades osteocondutoras, de reabsorção lenta, capaz de produzir tecido ósseo satisfatório. Porém, com quantidade semelhante ao coágulo aos 40 dias, o que gera maiores discussões e a necessidade de mais estudos para comprovar a eficácia desse biomaterial a longo prazo(AU)

The purpose of this study was to evaluate the bone regeneration process with the use of the Biogran® biomaterial, a bioactive glass, as a bone substitute option for grafting techniques in the maxillary sinus floor through histological and histomorphometric analysis. To that end, 24 New Zealand rabbits underwent a bilateral maxillary sinus removal procedure, and were divided into two groups: an implant clot group (ICG), in which the maxillary sinus was removed, followed by immediate implantation without graft ; and the implant bioglass group (GBI), in which the maxillary sinus was removed, filled with Biogran® and implanted in the immediate implant. The animals were submitted to euthanasia at 7, 15 and 40 days. The histological analysis showed a formation of gradual bone tissue in the GCI group, being larger at 40 days, with a lamellar characteristic. However, there was no statistical difference between the periods of 15 and 40 days of euthanasia (p = 0.210). The GBI group revealed a later bone formation with a greater amount at 40 days, with slow and progressive resorption of the biomaterial granules and signs indicative of osteoblastic activity. This group showed statistical difference between the periods of 7 and 15 days when compared to the 40 days (p <0.05). In the intergroup analysis, there was no statistically significant difference at 7 and 40 days, but at 15 days. Thus, it can be concluded that Biogran® is a biomaterial with osteoconductive properties, of slow resorption, able to produce satisfactory bone tissue. However, with a similar amount to the clot at 40 days, which generates more discussions and the need for further studies to prove the efficacy of this biomaterial in the long term(AU)

Radiographic analysis of dental implant extensions using bone grafts on dogs.

BACKGROUND: Despite the wide use of dental implants they can bring inconveniences, as the moment one reaches osseointegration, these can no longer be extended. Therefore, if a problem occurs regarding its positioning, the options open are substitution or burial of the implant. With implant substitution, there exists the risk of local bone loss and/or future loss of the new implant. PURPOSE: This study proposes a new device (implant extender) for extending the dental implant. The feasibility of this technique is verified through installing dental implant extensions onto the humerus bone of dogs with autogenous bone grafts. MATERIALS AND METHODS: Implants of 3.3 mm in diameter by 6 mm in length and implant extensions with a 3.3 mm diameter and 2.2 mm length were installed onto humerus of 4 healthy dogs, using an autogenous bone graft in a block made from ilium. The biomechanical percussion tests were performed on the implant extensions and then the implant-extension sets were removed for radiographic analysis. RESULTS: In the biomechanical percussion, none of the extensions present clinical mobility. As for the x-rays, these were analyzed by 20 professionals, who concluded that there was a 100% success rate with bone formation around the implants, 74.1% for bone neoformation of the implant extensions, and 80.1% referring to the adaptation of the implant extension. DISCUSSION AND CONCLUSION: Bone formation occurred in every installed dental implant. In most cases, there occurred bone neoformation of the extensions and adaptation of the extension/implant set, according to the x-ray analysis performed by the evaluators. An absence of clinical mobility in the extensions was also observed. Although the results were promising, these techniques still need to be researched in humans, as an alternative for reducing elongated prosthetic crowns or poorly installed implants, as well as the modification of the type of implants among other applications.

Morphological, comparative and qualitative tissue reaction analysis due to the implantation of alloplant™ to the eyelid and subcutaneous of rabbits / Análise morfológica comparativa e qualitativa da reação tecidual à colocação do alloplant™ (aloimplante) em pálpebra e dorso de coelhos

Purpose:To compare by optical microscopy, tissue reaction caused by the Alloplant ™ to conjunctiva and backs of 24 rabbits.Methods:All rabbits underwent implantation of Alloplant ™ on the inner third of the lower eyelid, replacing the tarsal conjunctiva of one eye. After thirty days six rabbits (Group I) were sacrificed and lower eyelids of both sides and a back fragment (control) routed to optical microscopy. After sixty days six rabbits (group II) were sacrificed and their eyelids and a back fragment (control) sent for microscopic examination. That day were also performed surgical implantation of Alloplant ™ on the back of the twelve remaining rabbits. They were sacrificed ninety days (group III) and one hundred and twenty days (group IV) after the first surgery of the eyelids and microscopic study backs.Results:The “Alloplant™” (aloimplante), caused an intense inflammatory reaction, mixed exudative and proliferative with a predominance of lymphocytes, macrophages and formation of foreign body granulomas in both locations, which evolved with the replacement of the implant by dense fibrous connective tissue.Conclusion:eyelid inflammatory reaction was more intense and more prolonged in the eyelid than in the back. In the back the formation of fibrosis was more intense, what is not suitable for eyelid surgery.

Objetivo:Analisar comparativamente através da microscopia óptica, a reação tecidual causada pelo Alloplant Ô na conjuntiva e dorso de 24 coelhos.Métodos:Todos os coelhos foram submetidos a implantação do AlloplantÔ no terço interno da pálpebra inferior, em substituição à conjuntiva tarsal de um dos olhos. Após trinta dias seis coelhos (grupo I) foram sacrificados e as pálpebras inferiores dos dois lados e um fragmento do dorso (controle) foram encaminhados para a microscopia óptica. Após sessenta dias foram sacrificados mais seis coelhos (grupo II) e suas pálpebras um fragmento do dorso (controle) foram encaminhados para estudo microscópico. Nesse dia também foram realizadas implantações cirúrgicas do aloimplanteÔ no dorso dos doze coelhos restantes, os quais foram sacrificados noventa (grupo III) e cento e vinte (grupo IV) dias após a primeira cirurgia para estudo microscópico das pálpebras e dorsos.Resultados:O “Alloplant Ԕ (aloimplante), causou intensa reação inflamatória mista exsudativa e proliferativa com predominância de linfócitos, macrófagos e formação de granulomas de corpo estranho nas duas localizações, que evoluiu com a substituição do implante por tecido conjuntivo fibroso denso.Conclusão:na pálpebra a reação inflamatória foi mais intensa e mais prolongada do que no dorso e no dorso a formação de fibrose foi mais intensa, mostrando inadequação ao uso cirúrgico.

Estudo experimental comparativo de remendos arteriais de polidimetilsiloxano com reforço de tecido de poliéster (PDMSr) versus politetrafluoretileno expandido (PTFEe) em aorta de coelhos / Patch of polydimethylsiloxane reinforced with polyester fabric for aortic angioplasty in rabbits

Introdução: Apesar de bons resultados descritos na literatura, o substituto ideal para a utilização como remendo no fechamento arterial ainda não existe. Por este motivo, ainda há espaço para a busca por remendo que seja biocompatível, e que apresente facilidade de manuseio e resultados satisfatórios. Avaliamos remendos arteriais de silicone (polidimetilsiloxano com reforço em poliéster - PDMSr) em comparação com remendos arteriais de PTFEe. Objetivo: O objetivo deste trabalho é comparar, em modelo experimental, em coelhos, os resultados de remendos arteriais feitos em PDMSr com remendos de PTFEe. Materiais e Método: A amostra foi definida em 10 animais que completassem todas as etapas da pesquisa em cada grupo. Os animais foram submetidos à laparotomia mediana e abertura longitudinal da aorta de aproximadamente 8mm, realizando-se o seu fechamento com remendo do grupo selecionado, seguido do fechamento por planos. Os animais foram mantidos em biotério até o 60º PO, quando, então, realizou-se arteriografia de controle, e análise macro e microscópica de peça. Resultados: Para se atingir a amostra desejada, foram necessários 12 procedimentos no grupo PDMSr e 16 no grupo PTFEe. Ocorreram 2 óbitos no grupo PDMSr e 6 no grupo PTFEe. Apesar do número maior de óbitos no grupo PTFEe não houve diferença estatística na sobrevida entre os grupos. Um animal do grupo PDMSr apresentou monoparesia em pata posterior direita e um animal do grupo PTFEe apresentou hérnia incisional. Não houve diferença estatística nas complicações entre os grupos. O tempo operatório foi estatisticamente maior no grupo PTFEe quando comparamos todos os animais, fato que não se repetiu quando excluímos os animais que faleceram...

Introduction: Although good results are reported for various materials for use as patches for arterial closure, as yet none of these is ideal. Therefore, research is continuing into development of a patch that is biocompatible and provides ease of handling, while having satisfactory outcomes. A new silicone arterial patch (polydimethylsiloxane reinforced with polyester fabric, PDMSr) was compared with patches made of expanded polytetrafluoroethylene (ePTFE). Objective: To compare the outcomes between arterial patches made of PDMSr with those made of ePTFE, in an experimental rabbit model. Materials and Method: Rabbits were placed in two groups, and received either PDMSr or ePTFE arterial patches (PDMSr group and ePTFE group, respectively). The animals underwent laparotomy and longitudinal opening of the aorta, which was then closed with the selected patch, followed by suture of all layers. The animals were kept in their cages until the 60th postoperative day, when arteriography, removal of the aorta, and macroscopic and optic and scanning electron microscopic analyzes of the aorta were performed. Ten rabbits from each group that had completed all stages of the research were included in analyses. Results: Twelve procedures were performed in the PDMSr group and 16 in the ePTFE group. There were 2 deaths in the PDMSr group and 6 in the ePTFE group. Despite the higher number of deaths in the ePTFE group, there was no statistical difference in survival rate between the groups. One animal in the PDMSr group developed monoparesis in its right hind paw and 1 animal in the ePTFE group had an incisional hernia. There was no statistical difference in complications between the groups. The operative time was significantly longer in the ePTFE group when all animals were included in analysis, but not when animals that died were excluded...

Implantes de polietileno poroso em calota de coelho: análise histológica comparativa / Porous Polyethylene Implants in Rabbit Calvarium: Histological Comparasion

O objetivo deste estudo foi comparar histologicamente o comportamento de implantes nacionais de polietilenoporoso (Polipore®) e de enxerto ósseo autógeno em defeitos ósseos em osso parietal de coelho. Foram utilizados 20 coelhos, os quais receberam osteotomias parietais bilaterais com o auxílio de uma trefina de 6mm dediâmetro. No Grupo I (GI), a cavidade foi preenchida com enxerto ósseo retirado do lado oposto, e, no GrupoII (GII), a cavidade foi preenchida com Polipore®. Não foram utilizados meios de fixação para os enxertos e implantes. Após 5, 15, 30, 60 e 120 dias, ocorreu a eutanásia dos animais, e as calotas cranianas foram processadas, segundo rotina histológica para coloração em H.E. Observou-se reação inflamatória discreta no(GI) aos 5 dias e moderada no GII, persistindo até aos 30 dias no GII. Os enxertos ósseos apresentaram-se incorporados ao leito receptor aos 120 dias. E somente aos 120 dias, no GII, observou-se presença de tecido conjuntivo no interior dos poros do implante. Concluímos que os enxertos foram eficientes na reparação do defeito ósseo, devido à incorporação ao leito receptor; O Polipore® foi biocompatível, mas não possui quantidadee tamanho de poros adequados para permitir o crescimento fibrovascular no interior do material

The aim of this study was to histologically compare national porous polyethylene implants and autogenous bone graft in cranial vault defects in rabbits. Cranial vaults defects were surgically created with a trephineburr of 6mm diameter in the parietal bones of 20 rabbits. In group I (GI) the bone defects were filled with autogenous bone graft from the contralateral parietal side, and in group II (GII), the bone defects were filledwith Polipore®. The grafts and implants were not fixed on the site. After 5, 15, 30, 60 and 120 days the animals were sacrificed and the cranial vaults were processed according to histological routine for stainingwith H&E. On the 5th day a discreet inflammatory reaction was observed in GI , while in GII, a moderate, inflammatory reaction persisted up to the 30th day. The bone grafts were incorporated to the host bedwithin 120 days. Only then, connective fibrous tissue was observed into the pores of the implant in GII. Bone grafts can efficiently repair bone defects, due to their incorporation into the bone host bed; the Polipore®implant is biocompatible, but does not have the adequate quantity and size of pores to permit fibrovascular tissue ingrowth into the material