Regeneração óssea guiada com o uso de matriz óssea bovina desmineralizada em defeitos ósseos experimentais em cães

Background: The principles of tissue regeneration to repair alveolar bone defects are based on the fabrication of a biologic barrier with different biomaterials. Therefore, the present study aimed to investigate the guided bone regeneration (GBR) by using membrane of demineralized bovine bone matrix (DBBM) on experimental defects in tibia of dogs. Methods: Four dogs were used and after anesthesia, shaving and antisepsis, two standardized bone defects were created on the right tibia of each animal with trephine drill. In the Control Group, the defects were filled with blood coagulum, while in the Treated Group, a membrane of DBBM was used to cover the defects. After 90 days, animals were sacrificed. Results: In the Treated Group, 67.4% of new bone formation was observed and, in the Control Group, 32.6% of the bone tissue reabsorbed when compared with initial bone volume. The membrane remained intact and no inflammatory tissue was observed on membrane/ bone interface. Conclusion: It was concluded that the use of DBBM is an osteoconductive material, presents biocompatibility and may be promise option to repair bone defects.

A proporção de plasma rico em plaquetas/enxerto ósseo autógeno pode influenciar o reparo ósseo de defeito de tamanho crítico: estudo radiográfico em calvária de ratos

Introduction: It has been suggested that bone grafts combined with platelet rich plasma (PRP) present greater density than bone grafts without PRP after healing process. However, this result may depend on proportion PRP/autogenous bone (AB) graft used. Objective: The purpose of this study was to analyze radiographically the influence of the proportion PRP/particulate autogenous bone (AB) graft on bone healing in surgically created criticalsize defects (CSD) in rat calvaria. Material and method: 50 rats were divided into 5 groups: C, AB, AB/PRP-50, AB/PRP-100 and AB/PRP-150. A 5 mm diameter CSD was created in the calvarium of each animal. In Group C the defect was filled by blood clot only. In Group AB the defect was filled with 0.01 mL of AB graft. In groups AB/ RP-50, AB/PRP-100 and AB/PRP-150 the defects were filled with 0.01 mL of AB graft combined with 50, 100 and 150 µL of PRP, respectively. All animals were euthanized at 30 days post-operative. Standardized radiographic images of the rat calvaria were obtained using Digora System (Soredex, Finland). The images were evaluated by three examiners using scores that indicated the percentage of radiopacity of the defect. The obtained data were subjected to statistical analysis (Kruskal-Wallis test, p < 0.05). Result: Group C presented radiopacity significantly lower than groups AB, AB/PRP-50, AB/PRP-100 and AB/PRP-150. Group AB/PRP-50 showed radiopacity significantly greater than groups AB/PRP-100 and AB. Conclusion: It can be concluded that the proportion PRP/AB graft influences bone healing in CSD in rat calvaria.

Impacto do controle glicêmico sobre as complicações associadas ao diabetes mellitus na osseointegração

The increased prevalence of diabetic individuals has become a public health problem. Diabetes Mellitus is a metabolic disorder characterized by an increase in plasma glucose levels. It impairs the physiological equilibrium in utilization of carbohydrate by tissues. The persistent hyperglycemia can produce deleterious effects on bone formation due the microvascular complication. The present paper reviews the bibliography linking the impact of glycemic control at complications associated at diabetes mellitus on osseointegration. In experimental models of diabetes it was observed a reduced level of bone-implant contact. This failure can be reduced by means of hyperglycemia control. Also, several studies point the beneficial effect of coated implant on osseointegration process. It is necessary to take special care into account for the placement of implants in diabetic patient and improve the percentages of implant survival. A rigorous control of plasma glycaemia, together with other measures, like as absence of chronic complications, good oral hygiene and regular medical follow-up has been related to rising the percentages of successful in diabetic patients.

Avaliação longitudinal de duas técnicas de sinus lift

The implant has high success rates and predictability in this decade. However, bone availability is a factor that may limit the installation technique of dental implants in subsequent rehabilitation of the maxillary arch has been proposed technique’s maxillary sinus lifting when it presents itself pneumatized, for installation of dental implants The aim of this paper is to present two clinical cases using the surgical technique and rehabilitation to the patient with surgery maxillary sinus lifting with the use of a biomaterial alone or in combination with autogenous bone and the prosthetic resolution radiographic and clinical follow-up of three years.

Comportamento biomecânico dos sistemas de retenção de overdentures

Objective: to the purpose of this study was to compare the stress distribution in the peri-implant hard tissue on different attachment systems for mandibular or maxillary implant-retained overdentures. Material and methods: the search for published studies was performed on PubMed/Medline database covering the period of January 2000 to April 2014. The selection of the eligible studies was performed according to including and excluding criteria. Results: a total of 140 studies were screened and according to the search strategy, 21 studies were selected for this review. Eight studies perfomed strain-gauge analysis, 5 evaluated the stress distribution though photoelastic test and 7 performed tridimensional finite element analysis. Only one study in vivo was included. Non-splinted O-rings showed better stress distribution than other bar-clip attachment systems. Conclusions: the present study did not find sufficient evidences regarding the most indicated attachment system for overdentures with better stress distribution for the peri-implant hard tissue. The methodologies analyzed should be complemented with other tests and used as a tool for further clinical studies.

Implantes Platform Switching: longevidade e preservação óssea: revisão crítica da literatura

The concept of switching platform is the use of an implant by platform wider than the abutment. Recently, researches have shown that this type of dental implant design tends to offer a higher preservation of crestal bone when compared to the traditional pattern of bone loss. The present study aims to perform a critical review on the switching platform concept establishing possible advantages of the technique. A search was performed on Medline/Pubmed about the topic “dental implant” and “platform switching”, and after applying inclusion criteria 40 studies were selected. The literature on longevity present prospective studies that show less bone loss, studies in biomechanics exhibit better or similar stress distribution around the bone crest, however, is not yet defined the role of the biological width. Thus, studies of longevity, and randomized prospective studies are of a great relevance to be performed in order to confirm the benefits of this technique and to establish a protocol indication. It is possible, based on this literature review, to conclude that longitudinal and randomized studies show that the platform switching implants have longevity and less bone loss. Biomechanically, the technique is possible.

Influência do material oclusal na distribuição de tensões em próteses implantossuportadas unitárias

Objective: the aim of this study was to evaluate the influence of occlusal veneering material in single fixed implant-supported crowns through the 3-D finite element method. Material and methods: Four models were fabricated using the Rhinoceros 4.0, SolidWorks, and InVesalius softwares. Each model represented a block of mandibular bone with an external hexagon implant of 5 mm x 10 mm and different veneering materials including NiCr (1), porcelain (2), composite resin (3), and acrylic resin (4). An axial load of 200 N and an oblique load of 100 N were applied. Results: model (2) with porcelain veneering presented a lower stress concentration for the NiCr framework, followed by the composite resin and acrylic resin. The stress distribution to the implant and bone tissue was similar for all models. Conclusions: there is no difference of stress distribution to the implant and supporting structures by varying the veneering material of a single implant-supported prosthesis.

Influência do material oclusal na distribuição de tensões em próteses implantossuportadas unitárias

Objective: the aim of this study was to evaluate the influence of occlusal veneering material in single fixed implant-supported crowns through the 3-D finite element method. Material and methods: Four models were fabricated using the Rhinoceros 4.0, SolidWorks, and InVesalius softwares. Each model represented a block of mandibular bone with an external hexagon implant of 5 mm x 10 mm and different veneering materials including NiCr (1), porcelain (2), composite resin (3), and acrylic resin (4). An axial load of 200 N and an oblique load of 100 N were applied. Results: model (2) with porcelain veneering presented a lower stress concentration for the NiCr framework, followed by the composite resin and acrylic resin. The stress distribution to the implant and bone tissue was similar for all models. Conclusions: there is no difference of stress distribution to the implant and supporting structures by varying the veneering material of a single implant-supported prosthesis.

Deslocamento de implante dentário para o seio maxilar: relato de caso

The residual alveolar ridges may be unfavorable for implant placement. The edentulous maxilla is often challenging for the oral surgeon because of the lack of bone as a consequence of alveolar ridge resorption and/or maxillary sinus pneumatization. Accidents or complications may occur when some of these issues are not being known. This article reports one case of implant displaced into the maxillary sinus, 27 days after sinus bone augmentation with simultaneous dental implant installation, causing moderated sinusitis symptoms. The implant was removed through oral cavity access to maxillary sinus.

Implantes osseointegrados: evolução e sucesso

Introduction: The oral rehabilitation with dental implants is a very viable treatment modality for patients. Therefore the discovery of osseointegration, dentistry has reached the trigger with respect to treatment with a high predictability of success. For this various principles, since the surgical protocols, the choice of material and even the technique for the manufacture of implant-supported prosthesis influence a good prognosis for treatment. Objective: Therefore, it is proposed this study a literature review of the fundamentals of osseointegration, explaining the historical and technical parameters of implantology, focusing in what the literature currently is studying with more intensity, the acceleration of osseointegration. Conclusion:well conducted procedures promotes the best aimed success in implantology. Rough surfaces shows great are for implant-bone contact and better mechanical results. The bone quality is fundamental in results foresigh.

Influência do formato do rebordo alveolar sagital em reabilitações com associação de prótese parcial removível de extremidade livre e implante ósseo integrado

The association of mandibular distal extension removable partial dentures with an osteointegrated implant is a treatment option at hasn't been fully explored by modern rehabilitation dentistry yet. The objective of this study is to evaluate, by means of the bidimensional method of finite elements, the distribution of tension on the structures supporting the distal extension removable partial denture (DERPD), associated to a 10.0 x 3.75 mm osteointegrated implant with an ERA retention system, in alveolar ridges of different shapes. Eight models were created, representing, from a sagittal perspective: Model A (MA) – a half arch with a horizontal ridge without posterior support, with the presence of the lower left canine, and a conventional DERPD, with metallic support in the incisal aspect of this canine, as replacement for the first and second pre-molars and the first and second molars of the lower left half arch; Model B (MB) – similar to MA, but different because of the presence of a 3.75 x 10.00 mm implant with an associated ERA retention system in the posterior region of the DERPD base; Model C (MC) - similar to MA, however with a distally ascending ridge format; Model D (MD) – similar to MC, but different because there is an implant associated to a retention system; Model E (ME) - similar to MA, however with a distally descending ridge format; Model F (MF) – similar to ME, but ditfferent in the sense that there is an implant with an associated ERA retention system; Model G (MG) – similar to MA, however with a distally descending-ascending ridge format; Model H (MH) – similar to MG, but different in the sense that there is an implant with an associated ERA retention system. The finite element program ANSYS 9.0 was used to load the models with vertical forces of 50 N, on each cuspid tip. The format of distal descending edge (ME and MF) was that presented worse results, so in the models with conventional RPD as in the models with RPD associated to the implant and ERA system of retention, for the structures gingival mucosa and tooth support. 1) the distally descending ridge presented the most significant stress in the model with the conventional RPD (ME) or with a prosthesis associated to an implant (MF) and 2) the horizontal ridge (MB) provided more relief to the support structures, such as the tooth and the spongy bone, when there was an implant associated to an ERA retention system. The incorporation of the implants with the ERA system retention, in the posterior area of the toothless edge, it promotes larger stability and retention to PPREL, improving the patient's masticatory acting and, consequently, its comfort and function.

The influence of the alveolar ridge shape on the stress distribution in a free-end saddle removable partial denture supported by implant

The alveolar ridge shape plays an important role in predicting the demand on the support tooth and alveolar bone in the removable partial denture (RPD) treatment. However, these data are unclear when the RPD is associated with implants. This study evaluated the influence of the alveolar ridge shape on the stress distribution of a free-end saddle RPD partially supported by implant using 2-dimensioanl finite element analysis (FEA). Four mathematical models (M) of a mandibular hemiarch simulating various alveolar ridge shapes (1-distal desceding, 2- concave, 3-horizontal and 4-distal ascending) were built. Tooth 33 was placed as the abutment. Two RPDs, one supported by tooth and fibromucosa (MB) and other one supported by tooth and implant (MC) were simulated. MA was the control (no RPD). The load (50N) were applied simultaneously on each cusp. Appropriate boundary conditions were assigned on the border of alveolar bone. Ansys 10.0 software was used to calculate the stress fields and the von Mises equivalent stress criteria (σvM) was applied to analyze the results. The distal ascending shape showed the highest σvM for cortical and medullar bone. The alveolar ridge shape had little effect on changing the σvM based on the same prosthesis, mainly around the abutment tooth.

Displasia cementária periapical: considerações sobre conduta e relato de caso

A displasia cementária periapical (DCP) consiste em uma lesão óssea não neoplásica geralmente assintomática, sendo detectada em exame radiográfico de rotina. Em seu primeiro estágio apresenta-se radigraficamente semelhante a uma lesão periapical inflamatória, todavia na DCP os dentes encontram-se vitais. Neste relato de caso foi realizado o acompanhamento por sete meses de uma paciente negra com 37 anos de idade afetada por DCP no periápice de incisivos, caninos e pré-molares inferiores bilateralmente. Ao exame radiográfico foi possível notar que a lesão apresentou-se em dois estágios: osteolítico e de maturação. Os dentes reagiram positivamente aos testes de vitalidade/sensibilidade pulpar descartando, com auxílio do exame de imagem, diversas hipóteses diagnósticas do grupo das periapicopatias crônicas, contribuindo assim para uma adequada escolha do tratamento, evitando iatrogenias.

Root reconstructed with mineral trioxide aggregate and guided tissue regeneration in apical surgery: a 5-year follow-up

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Influência da menopausa no tratamento endodôntico

A menopausa é uma das mudanças fisiológicas caracterizadas pelo encerramento dos ciclos menstrual e ovulatório, ocorrendo nas mulheres entre a quarta e a quinta década de vida. Com ela, ocorre uma diminuição na produção de estrógeno, um importante hormônio que atua em muitos processos fisiológicos do indivíduo, como a regulação do sistema esquelético. O declínio nos níveis de estrógeno resulta em perda de densidade mineral óssea, aumento do risco de fratura, bem como no aparecimento de doenças ósseas, como a osteoporose, um processo patológico onde há o aumento na reabsorção de cavidades que não são completamente preenchidas por osso neoformado. Além disso, a deficiência de estrógeno pode causar muitas mudanças na saúde bucal do indivíduo. Na presença de uma infecção bacteriana no tecido pulpar, essa deficiência pode agravar a periodontite apical. Vários medicamentos têm sido estudados como potenciais agentes terapêuticos para suprir a deficiência de estrógeno. Essas drogas têm como objetivo reduzir o risco de fraturas e prevenir a perda óssea e distúrbios cardiovasculares e mentais resultantes de deficiência hormonal pós-menopausa. O raloxifeno (RLX), é uma das drogas terapêuticas mais estudadas, demonstrando prevenir a perda óssea. Mesmo com a indicação e benefícios do raloxifeno no metabolismo ósseo e na manutenção da densidade óssea, estudos sobre o seu papel na infecção endodôntica em organismos osteopênicos precisam ser realizados.