Assessment of Deviations of Implants Installed with Prototyped Surgical Guide and Conventional Guide: In Vitro Study.

OBJECTIVE: The study aimed to assess the angular and linear deviations of implants installed in mannequins aided by surgical guides produced with the techniques of dual tomography (DT), model-based tomography (MT), and nonprototyped guide. MATERIALS AND METHODS: Implants were installed in mannequins of a partially edentulous maxilla and divided into three groups: Group C (n = 20), implants installed using the conventional technique with flap opening and conventional guide; Group DT (n = 20), implants installed using guided surgery with the dual tomography technique; and Group MT (n = 20), implants installed using the model-based tomography technique. After implant installation, the mannequin was subjected to a computed tomography (CT) to measure the linear and angular deviations of implant positioning relative to the initial planning on both sides. RESULTS: There was a higher mean angular deviation in group C (4.61 ± 1.21, p ≤ 0.001) than in groups DT (2.13 ± 0.62) and MT (1.87 ± 0.94), which were statistically similar between each other. Similarly, the linear deviations showed group C with the greatest discrepancy in relation to the other groups in the crown (2.17 ± 0.82, p = 0.007), central (2.2 ± 0.77, p = 0.004), and apical (2.34 ± 0.8, p = 0.001) regions. CONCLUSION: The techniques of DT and MT presented smaller angular and linear deviations than the conventional technique with the nonprototyped guide. There was no difference between the two-guided surgery techniques.

A new multiphase calcium phosphate graft material improves bone healing-An in vitro and in vivo analysis.

This study aims to evaluate the potential of a novel biomaterial synthesized from amorphous calcium phosphate (ACP), octacalcium phosphate (OCP), and hydroxyapatite (HA) to repair critical-sized defects (CSD) in rabbit calvaria. In vitro analyses of cell viability, cell proliferation, formation of mineral nodules, and cell differentiation using qPCR were performed for comparing experimental calcium phosphate (ECP), deproteinized bovine bone (DBB), and beta-tricalcium phosphate (ß-TCP). Bilateral CSDs were created in 45 rabbit calvaria. Six groups were evaluated: ECP, ECP + fibrin sealant (ECP + S), coagulum, autogenous bone, DBB, and ß-TCP. Euthanasia was performed at 2, 4, and 8 weeks, followed by micro-computed tomography and histological and immunohistochemical analyses. Results from in vitro analyses revealed similar biocompatibility for all tested materials and a tendency for higher gene expression of some bone markers in the ECP group than in ß-TCP and DBB groups at 7 days. In contrast to that in DBB and ß-TCP groups, ECP displayed growing bone volume over total volume percentage (BV/TV%) with time in vivo. Histological analysis revealed a greater number of giant cells and reduced size of grafted particles in ECP during all periods of analysis. RUNX-2 expression was statistically lower in ECP than DBB at 2 and 4 weeks. Despite no statistical significance, ECP presented the highest absolute values for ALP-expression at 2, 4, and 8 weeks compared with other groups. Together, our findings indicate that a combination of the ACP, OCP, and HA phases into ECP is beneficial and promising for bone regeneration.

Local delivery of strontium ranelate promotes regeneration of critical size bone defects filled with collagen sponge.

The effect of local delivery of strontium ranelate (SR) on bone regeneration of critical size bone defects filled with collagen sponge was evaluated. Bone defects of 5 mm diameter created in rat calvaria were filled with collagen sponge (C); collagen sponge with 5 mM Sr2+ SR (C5SR) or collagen sponge with 50 mM Sr2+ SR (C50SR). After 2, 4, and 6 weeks, bone volume (BV), bone surface (BS), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular separation (Tb.Sp) were evaluated by computed microtomography. At 6 weeks, histological analysis was performed. Intragroup comparisons were made by the Friedman test, while comparisons between groups were made by Kruskal-Wallis test (α = 5%). All groups showed increased BV, BS, Tb.Th, and Tb.N over time, but only C50SR promoted the reduction of Tb.Sp (p < 0.05). No significant differences between groups were detected at weeks 2 and 4. However, C50SR showed the highest values of BV, BS, and Tb.Th at 6 weeks (p < 0.05). Histological analysis revealed connective tissue in C and C5SR and immature bone tissue in C50SR. Local delivery of SR 50 mM Sr2+ associated with collagen sponge increased and accelerated bone regeneration in critical bone defects. © 2017 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 106A: 333-341, 2018.

Glycemic control protects against trabecular bone microarchitectural damage in a juvenile male rat model of streptozotocin-induced diabetes.

PURPOSE: To determine which features of the bone microarchitecture are affected by established diabetes mellitus (DM) and the effectiveness of glycemic control in the protection of bone tissue. MATERIAL AND METHODS: Sixty juvenile Wistar male rats were divided into three groups of 20 animals: a control group (C) that included healthy animals, a diabetic group (D) that included animals with induced diabetes, and a controlled diabetic group (CD) that included animals with induced diabetes that were treated with insulin. The animals were euthanized at the periods of 6 and 8 weeks after the induction of diabetes (10 animals per group/period). Vertebral L4 specimens were submitted to µCT analysis to assess the following parameters of the bone microarchitecture: bone volume fraction (BV/TV), trabecular thickness (Tb.Th), trabecular number (Tb.N), and trabecular spacing (Tb.Sp). RESULTS: The D group exhibited lower values of BV/TV (%) and numbers of trabeculae compared with the C group at 6 and 8 weeks and compared with the CD group at 8 weeks. The CD group exhibited higher trabecular thickness values compared with the D group at 8 weeks. There were no differences between the groups regarding the spaces between the trabeculae. CONCLUSION: Induced diabetes affected the microarchitecture of the trabecular bone of the vertebrae by reducing the values of the majority of the parameters in relation to those of the control group. Glycemic control with insulin appears to protect bones from the effects of the hyperglycemia.

Rehabilitation of the maxillary arch after bone graft using immediate loading with implant-supported fixed restoration.

Moderate and controlled loading environments support or enhance osteogenesis, and, consequently, a high degree of bone-to-implant contact can be acquired. This is because when osteoprogenitor cells are exposed to limited physical deformation, their differentiation into osteoblasts is enhanced. Then, some range of microstrain is considered advantageous for bone ingrowth and osseointegration. The primary stability has been considered one of the main clinical means of controlling micromotion between the implant and the forming interfacial tissue, which helps to establish the proper mechanical environment for osteogenesis. Based on the biological aspects of immediate loading (IL), the objective of this study is to present a clinical case of maxillary arch rehabilitation using immediate loading with implant-supported fixed restoration after bone graft. Ten dental implants were placed in the maxilla 6 months after the autogenous bone graft, removed from the mandible (bilateral oblique line and chin), followed by the installation of an immediate-load fixed cross-arch implant-supported restoration because primary stability was reached for 8 implants. In addition, instructions about masticatory function and how it is related to interfacial micromotion were addressed and emphasized to the patient. The reasons for the IL were further avoidance of an interim healing phase, a potential reduction in the number of clinical interventions for the patient, and aesthetic reasons. After monitoring the rehabilitation for 8 years, the authors can conclude that maxillary IL can be performed followed by a well-established treatment planning based on computed tomography, providing immediate esthetics and function to the patient even when autogenous bone graft was previously performed in the maxilla.

Bio-Oss versus Bone Ceramic para elevação bilateral de seio maxilar no mesmo paciente: avaliação histológica qualitativa após seis meses / Bio-Oss versus Bone Ceramic in sinus floor elevation procedures in the same patient: qualitative histological evaluation after six months

O objetivo do presente caso clínico foi avaliar histologicamente o comportamento do Bio-Oss e do Bone Ceramic, utilizados separadamente, para elevação bilateral dos seios maxilares de um paciente com 49 anos, do sexo feminino, que procurou a Escola de Odontologia de Cuiabá/MT para reabilitação implantossuportada. Após bloqueios anestésicos adequados, foi realizada em cada hemimaxila a incisão tecidual com lâmina de bisturi de número 15. Para acesso ao rebordo maxilar atrófico, foi feito o descolamento do retalho total utilizando o descolador de Molt. Posteriormente, no rebordo maxilar atrófico, foi confeccionada uma janela lateral utilizando-se broca esférica diamantada. A parede anterior do seio foi ostectomizada, a membrana sinusal foi deslocada e elevada, sem qualquer perfuração. Subsequentemente, foram realizadas as inserções dos biomateriais: Bio-Oss (lado direito) e Bone Ceramic (lado esquerdo), por um único cirurgião-dentista. Após seis meses, foram obtidas biópsias bilaterais que foram processadas para inclusão em parafina. Cortes foram corados com hematoxilina e eosina para análise histológica qualitativa. Os achados histológicos deste caso clínico confirmam as propriedades osteocondutivas dos biomateriais investigados, visto que foram observados íntimos contatos entre o Bio-Oss ou o Bone Ceramic e o tecido ósseo neoformado. Porém, parece haver uma maior presença de tecido ósseo neoformado ao redor do Bio-Oss. Além disso, ao redor do Bone Ceramic, maior quantidade de células inflamatórias é observada. Apesar dos resultados indicarem ligeira superioridade do Bio-Oss, estudos envolvendo um maior número de pacientes devem ser realizados, a fim de confirmar os achados deste caso clínico.

The aim of this case report was to evaluate from the histologic aspect the behavior of Bio-Oss and Bone Ceramic for bilateral maxillary sinus elevation in a 49 years-old female patient. After adequate anesthesia, an incision was placed with a scalpel blade and the mucoperiosteal flap was elevated. Then, a lateral window was made with a round diamond bur. An osteotomy was placed in the anterior sinus wall, the sinus membrane was dislocated without perforation. After, Bio-Oss (right side) and Bone Ceramic (left side) were packed by the same surgeon. Six months later, biopsies were obtained and processed with H&E staining. The histological findings confirmed osteoconductive properties of both materials with close contact at the newly formed bone. However, more bone tissue seems to be available around Bio-Oss. Besides, more inflammation was seen around Bone Ceramic. Although the results indicate a slight superiority for Bio-Oss, more studies with a great sample size are necessary to corroborate the findings of this clinical report.

Reabilitação total dos maxilares com carga imediata / Full mouth rehabilitation using immediate implant loading

O carregamento moderado e controlado dos implantes suporta e reforça a osteogênese, podendo aumentar a superfície de contato osso-implante. Isto ocorre porque quando as células osteoprogenitoras são expostas a uma deformação física limitada, a sua diferenciação em osteoblastos é melhorada. Neste momento, alguma variação de microtensão é considerada vantajosa para a neoformação óssea assim como para a osseointegração. A estabilidade primária é um dos principais pré-requisitos clínicos para o controle da micromovimentação entre o implante e o tecido de formação interfacial, o que ajuda a determinar o ambiente mecânico adequado para a osteogênese. Com base nos aspectos biológicos do carregamento de implantes imediatos, o objetivo deste estudo é apresentar um caso clínico de reabilitação total dos maxilares com carga imediata. Sete implantes foram colocados na maxila e seis na mandíbula seguindo-se a instalação de duas próteses do tipo protocolo com carga imediata, uma vez que a estabilidade primária foi alcançada para todos os implantes. Instruções sobre a função mastigatória e como ela está relacionada com a micromovimentação dos implantes foram abordadas e enfatizadas para o paciente. A razão por essa opção de tratamento foi de reduzir o tempo de tratamento, devolução de estética e função para o paciente. Após dois anos de acompanhamento clínico, os autores concluíram que a reabilitação maxilomandibular simultânea com carga imediata pode ser indicada e realizada após um planejamento adequado do caso clínico com base na tomografia computadorizada, proporcionando estética e função imediatas para o paciente

Moderate and controlled loading of the implants support or enhance osteogenesis, which may augment the bone-to-implant contact area. This occurs because when osteoprogenitor cells are exposed to limited physical deformation, their differentiation into osteoblasts is enhanced. Then, some range of microstrain is considered advantageous for bone ingrowth and osseointegration. The primary stability has been considered one of the main clinical requisitions for controlling micro motion between the implant and the forming interfacial tissue, which helps to establish the proper mechanical environment for osteogenesis. Based on the biological aspects of immediate implant loading, the objective of this study was to present a clinical case of immediate full mouth rehabilitation. Seven dental implants were placed in the maxilla and six in the mandible followed by the installation of both immediate- -load prosthetic protocols, once primary stability was reached for all implants. In addition, instructions about masticatory function and its relation with interfacial micro motion were addressed and emphasized to the patient. This treatment was chosen aiming at reducing the period of treatment and restore function and aesthetics. After a 2 year follow-up of the rehabilitation, the authors could conclude that simultaneous maxillomandibular rehabilitation with immediate loading can be indicated and performed after a well establish treatment planning based on computed tomography, providing immediate aesthetic and function to the patient

Structural and functional changes in the alveolar bone osteoclasts of estrogen-treated rats.

This study investigated structural and functional features of apoptotic alveolar bone osteoclasts in estrogen-treated rats. For this purpose, 15 female rats 22 days old were divided into three groups: Estrogen (EG), Sham (SG) and Control (CG). The rats of EG received daily intramuscular injection of estrogen for 7 days. The SG received only the oil vehicle. Maxillary fragments containing alveolar bone were removed and processed for light and transmission electron microscopy. Area (OcA) and number of nuclei (OcN) and bone resorption surface per TRAP-positive osteoclasts (BS/OC) were obtained. Vimentin, caspase-3 and MMP-9 immunoreactions, TUNEL/TRAP and MMP-9/TUNEL combined reactions were performed. In EG, the OcA, OcN and BS/Oc were reduced. Moreover, osteoclasts showed cytoplasm immunolabelled by caspase-3 and a different pattern of vimentin expression in comparison with CG and SG. MMP-9 expression was not affected by estrogen and the TUNEL-positive osteoclasts were MMP-9-immunolabelled. In EG, ultrastructural images showed that apoptotic osteoclasts did not exhibit ruffled borders or clear zones and were shedding mononucleated portions. TRAP-positive structures containing irregular and dense chromatin were partially surrounded by fibroblast-like cells. In conclusion, the reduction in the BS/Oc may be due to reduction in OcA and OcN; these effects seem to be related to vimentin disarrangement rather than to an interference of estrogen with osteoclast MMP-9 expression. Osteoclast apoptosis involves caspase-3 activity and vimentin degradation; these cells release portions containing one apoptotic nucleus and, subsequently, undergo fragmentation, giving rise to apoptotic bodies.

Aspectos biológico-celulares da osseointegração baseados nos implantes dentários / Osseointegration: biological and cellular aspects based on implant surfaces no keywords: dental implants

A Osseointegração envolve uma cascata de eventos biológico-celulares, que podem ser acelerados por meio da modificação micro e/ou nanométrica da topografia da superfície dos implantes dentais. Considerando-se que diferentes tipos de tratamentos modificam a superfície do titânio, conferindo-lhe uma topografia mais rugosa, além de alterações físico-químicas que parecem influenciar positivamente a osseointegração, foi realizada uma revisão da literatura sobre os principais tipos de tratamentos de superfícies de implantes de titânio e sua influência na Osseointegração do ponto de vista biológico-celular. Para a realização deste estudo foi feito um levantamento bibliográfico de publicações que datam de 1969 até o presente. Apesar do papel preciso da topografia e da química de superfície sobre a osseointegração de implantes dentários não estar completamente elucidado, os efeitos específicos da superfície de implantes sobre regeneração óssea inicial, cinética e evolução das propriedades mecânicas têm se mostrado bastante promissores. Assim, baseado nas modificações das superfícies de implantes dentais, a Osseointegração pode ser definida como um processo pelo qual a fixação rígida e assintomática de um material aloplástico pode ser alcançada e mantida em íntimo contato com o tecido ósseo, apresentando resistência às cargas funcionais precoces e tardias, podendo este processo ser modulado pelo adequado tratamento da superfície do material aloplástico.

Osseointegration involves a cascade of biological events, which can be accelerated by modifying the micro and/or nanometric topography of dental implant surfaces. Considering that different treatment types modify the titanium surface giving it a more pronounced rough topography, and physicochemical changes that appear to positively influence the osseointegration process, a literature review was made on the main types of surface treatments and their influence on the biological and cellular aspects of osseointegration, with publications dating from 1969 until the present moment. Although the precise role of the implant surface on the osseointegration of dental implants is not completely clear, the specific effects of implant surface on bone regeneration, initial kinetics, and evolution of mechanical properties have shown to be quite promising. Thus, based on dental implant surface modifications, osseointegration can be defined as a process by which rigid asymptomatic fixation of an alloplastic material can be achieved and kept in close contact with bone tissue, being resistant to early and late functional loads. This process can be modulated by an appropriate treatment of the alloplastic material surface.

Mecanismos celulares e moleculares do estrógeno na reabsorção óssea / Cellular and molecular mechanisms of the estrogen in the bone resorption

O osso é um tecido conjuntivo mineralizado cuja homeostase está sob a influência de diversos fatores sistêmicos e locais. Entre os fatores sistêmicos, sabe-se que o estrógeno é um hormônio que inibe a reabsorção óssea e, por essa razão, tem sido amplamente utilizado no tratamento e na prevenção da osteoporose. Os mecanismos de ação do estrógeno na reabsorção óssea não estão completamente esclarecidos. Assim, nesta revisão, está descrito o papel do estrógeno no tecido ósseo, enfocando alguns mecanismos celulares e moleculares de ação desse hormônio. Informações clínicas a respeito da possível relação entre osteoporose, homeostase dos ossos maxilares e tratamentos dentários foram também incluídas nesta revisão. De acordo com os dados da literatura, o estrógeno atua na via RANK/RANKL/OPG, inibindo a formação de osteoclastos. Também tem sido mostrado que o estrógeno promove a apoptose de osteoclastos e, assim, diminui a reabsorção óssea. Esse hormônio também reduz a reabsorção óssea inibindo proteases produzidas por osteoclastos. Se o estrógeno age diretamente em osteoclastos, ou indiretamente por meio dos osteoblastos, ainda é controverso. Porém, pode-se concluir que o estrógeno inibe a reabsorção óssea agindo em vias relacionadas à formação, à atividade e à sobrevivência dos osteoclastos. Considerando-se que tem sido observada uma correlação entre osteoporose e perda óssea nos maxilares, o conhecimento dos mecanismos do estrógeno na reabsorção óssea, pelo cirurgião-dentista, pode contribuir para o sucesso de diversos tratamentos dentários. Além disso, o cirurgião-dentista pode contribuir para o diagnóstico dessa patologia, bem como encaminhar o paciente para um tratamento especializado.

Bone is a mineralized connective tissue that depends upon numerous interacting systemic and local factors for its homeostasis. Among systemic factors, it is known that estrogen is a hormone, which exerts an inhibitory function on bone resorption and, for this reason, it has been widely used in the treatment and prevention of osteoporosis. The mechanisms of action of the estrogen on bone resorption are not completely understood. Thus, in this review, we described the role of the estrogen in the bone, focusing on some cellular and molecular mechanisms of action of this hormone. Clinical information concerning possible association among osteoporosis, oral bone homeostasis and dental treatments were also included in this review. According to literature, estrogen acts on the RANK/RANKL/OPG system, inhibiting osteoclastogenesis. It has also been shown that estrogen promotes osteoclasts apoptosis and thereby decreases bone resorption. Moreover, estrogen reduces bone resorption by inhibiting proteases produced by osteoclasts. Whether estrogen acts directly on osteoclasts, or indirectly through osteoblasts, is still controversial. However, we may conclude that estrogen inhibits bone resorption by acting on pathways associated with the formation, activity and survival of osteoclasts. Since a relationship between osteoporosis and oral bone loss has been observed, the knowledge of the mechanisms of the estrogen on bone resorption by the dentist may contribute to the prognosis and success of several dental treatments. Besides, the dentist can contribute to diagnosis of the osteoporosis and to indicate the pacient to an specialized treatment.