Effect of Misfit on Preload Maintenance of Retention Screws of Implant-Supported Prostheses

The aim of this study was to evaluate the effect of unilateral misfit at different levels on a crown-implant-retention screw system of implant-supported crowns. Hexagon castable UCLA abutments were cast in Co-Cr alloy to fabricate 48 metallic crowns divided into four groups (n = 12). Group A: crowns did not present misfit; Groups B, C and D: crowns were fabricated with unilateral misfit of 50, 100, and 200 mu m, respectively. The crowns were attached by titanium retention screw with 30 N/cm to external hexagonal osseointegrated implants embedded in acrylic resin. After 2 min, the retention screw of each replica was submitted to detorque evaluation by an analogic torque gauge. Three retention screws were used to perform detorque evaluation at each replica and the procedure was repeated twice with each screw. Each group was submitted to 72 detorque measurements. Data were evaluated by ANOVA and Tukey test (P < 0.05). All groups exhibited significant decrease (P < 0.05) in preload and the lowest decrease occurred in Group A. Groups B, C, and D were statistically significant different from Group A (P < 0.05), but there was no statistically significant difference between Groups B and D (P > 0.05). Crowns with unilateral misfit presented higher preload decrease than crowns completely fitted to osseointegrated implants.

Interleukin-1 beta and Interleukin-6 Expression and Gene Polymorphisms in Subjects with Peri-Implant Disease

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

A Strain Gauge Analysis of Microstrain Induced by Various Splinting Methods and Acrylic Resin Types for Implant Impressions

Purpose: The aim of this study was to investigate the level of microstrain that is exerted during polymerization of acrylic resins used for splinting during implant impressions. Material and Methods: Two acrylic resins (GC Pattern Resin, Duralay II) and square transfer coping splinting methods were evaluated by means of strain gauge analysis. Two implants were embedded in a polyurethane block, and the abutments were positioned. Sixty specimens were prepared using two square transfer Copings that were rigidly connected to each other using the acrylic resins. The specimens were randomly divided into three groups of 20 each for the splinting methods: Method 1 was a one-piece method; in method 2, the splint was separated and reconnected after 17 minutes; and in method 3, the splint was separated and reconnected after 24 hours. In each group, half the specimens were splinted with GC Pattern Resin and the other half were splinted with Duralay II. Three microstrain measurements were performed by four strain gauges placed on the upper surface of the polyurethane blocks at 5 hours after resin polymerization for all groups. The data were analyzed statistically. Results: Both resin type and splinting method significantly affected microstrain. interaction terms were also significant. Method 1 in combination with Duralay II produced significantly higher microstrain (1,962.1 mu epsilon) than the other methods with this material (method 2: 241.1 mu epsilon; method 3: 181.5 mu epsilon). No significant difference was found between splinting methods in combination with GC Pattern Resin (method 1: 173.8 mu epsilon; method 2: 112.6 mu epsilon; method 3: 105.4 mu epsilon). Conclusions: Because of the high microstrain generated, Duralay II should not be used for one-piece acrylic resin splinting, and separation and reconnection are suggested. For GC Pattern Resin, variations in splinting methods did not significantly affect the microstrain created. Int J Oral Maxillofac Implants 2012;27:341-345

Retention force and fatigue strength of overdenture attachment systems

This study evaluated retention force and fatigue resistance of two overdenture attachment systems. Twenty samples (O-ring and Bar-Clip) from two manufacturers (Conexao Sistemas de Protese and Lifecore Biomedical) were prepared and divided into four groups: (i) Conexao/O-ring; (ii) Conexao/Bar-Clip; (iii) Lifecore/O-ring and (iv) Lifecore/Bar-Clip, with five samples in each group. They were submitted to mechanical fatigue test using a servohydraulic machine performing 5500 cycles of insertion and removal (f=0.8 Hz), immersed in artificial saliva. Retention force values were obtained three times (0, 3000 and after 5500 cycles) simulating the clinical service, using a tensile strength at 1 mm min(-1) and load cell of 1 kN. Data were analysed with analysis of variance and Tukey's test at 5% level. Results showed that Conexao/Bar-Clip specimens had significantly higher retention values than Lifecore/Bar-Clip (44.61 and 18.44 N, respectively), Conexao/O-ring specimens had significantly lower values than Lifecore/O-ring (13.91 and 19.75 N, respectively). Conexao/Bar-Clip values were always significantly higher than those of Conexao/O-ring group (44.61 and 13.91 N, respectively). Lifecore (O-ring and Bar-Clip) presented similar values (19.75 and 18.44 N, respectively). The systems evaluated showed satisfactory retention force values, before and after fatigue testing. Conexao/Bar-Clip specimens presented the highest values. A 5-year simulation of insertion and removal did not decrease retention values or fracture components.

Prosthetic rehabilitation of a bone defect with a teeth-implant supported, removable partial denture

The use of teeth-implant, mucosa-supported removable dentures for rehabilitation of partially edentulous patients involves highly complex biomechanical aspects. This type of prosthesis associates 3 kinds of support that react differently to the functional and parafunctional forces developed in the oral cavity. Although the construction of removable partial dentures may seem paradoxical when osseointegrated implants are placed, in some cases, this option is an excellent alternative to solve difficulties related to the anatomic, biologic, psychomotor, and financial conditions of the patient. This article reports on a case in which a teeth-implant, mucosa-supported removable partial denture was the option of choice for a patient with financial and anatomic limitations, having a large structural loss of the residual alveolar ridge caused by trauma by a gunshot injury at the mandible. The 5-year follow-up did not reveal any type of biomechanical or functional problem. Copyright © 2006 by Lippincott Williams and Wilkins.

Instalación inmediata de prótesis provisionales en la reapertura de implantes

The study of techniques to reach aesthetics in the anterior region when using osseointegrated implants is of great importance. A literature review was made to compare effivciency and suitability of immediate provisionalization in re-opening of osseointegrated implants with respect to the set time (use of standardized cicatrizants and emergency profile cicatrizants). Immediate provisional denture in the phase of re-opening makes the restoration of the gingival contourn quicker when compared to the use of cicatrizants without intermediate phases required. © 2008 1995, Editorial Ciencias médicas.

Comparison of manual versus sonic and ultrasonic toothbrushes: a review.

PURPOSE: This review of the literature intends to evaluate the effect of brushes with high frequency motion when compared with manual toothbrushes regarding the indices of plaque and gingival bleeding. METHODS: Patients presenting gingivitis and/or chronic periodontitis were evaluated in addition to patients having osseointegrated implants and fixed orthodontic appliances. Pertinent literature was reviewed to select articles according to previously defined inclusion criteria. RESULTS: In the assessed studies results showed significant decreases in plaque and gingival indices by utilization of both types of brushes. However, in the selected studies where sonic brushes were tested in orthodontic and dental implant patients there was a more significant decrease in the indices. Furthermore, there was no indication of gingival recession attributed to product use. CONCLUSION: Future studies with a more homogeneous methodology and better experiment designs will be needed.

Titanium in Dentistry: Historical development, state of the art and future perspectives

Titanium is a metallic element known by several attractive characteristics, such as biocompatibility, excellent corrosion resistance and high mechanical resistance. It is widely used in Dentistry, with high success rates, providing a favorable biological response when in contact with live tissues. Therefore, the objective of this study was to describe the different uses of titanium in Dentistry, reviewing its historical development and discoursing about its state of art and future perspective of its utilization. A search in the MEDLINE/PubMed database was performed using the terms 'titanium', 'dentistry' and 'implants'. The title and abstract of articles were read, and after this first screening 20 articles were selected and their full-texts were downloaded. Additional text books and manual search of reference lists within selected articles were included. Correlated literature showed that titanium is the most used metal in Implantology for manufacturing osseointegrated implants and their systems, with a totally consolidated utilization. Moreover, titanium can be also employed in prosthodontics to obtain frameworks. However, problems related to its machining, casting, welding and ceramic application for dental prosthesis are still limiting its use. In Endodontics, titanium has been used in association to nickel for manufacturing rotatory instruments, providing a higher resistance to deformation. However, although the different possibilities of using titanium in modern Dentistry, its use for prostheses frameworks still needs technological improvements in order to surpass its limitations. © 2012 Indian Prosthodontic Society.

Aplicação do copolímero PLA/PGA adicionado ao fosfato de cálcio ao redor de implantes osseointegráveis instalados sem estabilidade primária em tíbia de coelhos: estudo biomecânico, histométrico e imunoistoquímico

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Avaliação do copolímero de ácido polilático e poliglicólico ao redor de implantes osseointegráveis sem estabilidade primária: análise biomecânica, histométrica e imunoistoquímica em coelhos

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

Análise histológica de defeitos ósseos preenchidos com biomateriais e associados a implantes osseointegrados. Estudo em cães

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Efeito da deficiência de magnésio na dieta sobre a densidade e o metabolismo ósseo ao redor de implantes com osseointegração estabelecida: estudos em ratos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Avaliação da influência da angulação do implante osseointegrado associado à prótese parcial removível classe I mandibular pelo método dos elementos finitos

Pós-graduação em Odontologia - FOA

Avaliação da influência da força de mordida na prótese parcial removível classe I mandibular associada ao implante osseointegrado, pelo método dos elementos finitos

Pós-graduação em Odontologia - FOA

Avaliação da influência do diâmetro e comprimento do implante osseointegrado associado à PPR Classe I mandibular pelo método dos elementos finitos

Pós-graduação em Odontologia - FOA