Use of Stress Analysis Methods to Evaluate the Biomechanics of Oral Rehabilitation With Implants

Because the biomechanical behavior of dental implants is different from that of natural tooth, clinical problems may occur. The mechanism of stress distribution and load transfer to the implant/bone interface is a critical issue affecting the success rate of implants. Therefore, the aim of this study was to conduct a brief literature review of the available stress analysis methods to study implant-supported prosthesis loading and to discuss their contributions in the biomechanical evaluation of oral rehabilitation with implants. Several studies have used experimental, analytical, and computational models by means of finite element models (FEM), photoelasticity, strain gauges and associations of these methods to evaluate the biomechanical behavior of dental implants. The FEM has been used to evaluate new components, configurations, materials, and shapes of implants. The greatest advantage of the photoelastic method is the ability to visualize the stresses in complex structures, such as oral structures, and to observe the stress patterns in the whole model, allowing the researcher to localize and quantify the stress magnitude. Strain gauges can be used to assess in vivo and in vitro stress in prostheses, implants, and teeth. Some authors use the strain gauge technique with photoelasticity or FEM techniques. These methodologies can be widely applied in dentistry, mainly in the research field. Therefore, they can guide further research and clinical studies by predicting some disadvantages and streamlining clinical time.

Inhibition of tooth erosion by milk containing different fluoride concentrations: An in vitro study

Objectives: This in vitro study assessed the effect of milk containing different fluoride concentrations on tooth erosion.Methods: Bovine enamel and root dentine specimens were treated with: (1) bovine whole milk with 0 ppmF; (2) 2.5 ppm F; (3) 5 ppmF;(4) 10 ppmF (all after erosion); (5) whole milk with 0 ppm F (before erosion); (6) NaF (0.05% F, positive control, after erosion) or (7) 0.9% NaCl (negative control, after erosion). The specimens were submitted to pH cycles (4 x 90 s in soft drink) and treatments for 5 days. The specimens were immersed in the treatment solutions for 1 min(only at the first cycle each day) with further exposition to 1: 1 milk: saliva slurry for 10 min. The tooth loss was measured using a contact profilometer and statistically analysed (p < 0.05).Results: Rinsing with milk before erosive challenge significantly reduced tooth loss compared to negative control (67% and 24% reduction in dentine and enamel loss, respectively) and to milk after erosive challenge, only for dentine. The addition of fluoride to milk also reduced tooth loss compared to negative control, but with no significant differences among fluoride concentrations for enamel and dentine (mu m), respectively: 0 ppm (3.63 +/- 0.04 and 2.51 +/- 0.53), 2.5 ppm F (2.86 +/- 0.42 and 1.96 +/- 0.47), 5 ppm F (2.81 +/- 0.27 and 1.77 +/- 0.44), 10 ppm F (2.03 +/- 0.49 and 1.68 +/- 0.59). There was a negative and significant correlation between [F] and the tooth loss.Conclusions: Daily rinse with milk containing F is able to reduce both enamel and dentine erosion in vitro.Clinical significance: Since the prevalence of dental erosion is steadily increasing, rinse with milk or its derivate might be an important strategy to reduce the progression of tooth erosion. (C) 2013 Elsevier Ltd. All rights reserved.

The effect of chronic treatment with fluoride on salivary activity, tooth, and bone in spontaneously hypertensive rats (SHR)

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Clinical Trial Evaluating Color Change and Tooth Sensitivity Throughout and Following In-office Bleaching

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

Effective tooth-bleaching protocols capable of reducing H2O2 diffusion through enamel and dentine

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

Eight-Year Follow-Up of a Fixed-Detachable Maxillary Prosthesis Utilizing an Attachment System: Clinical Protocol for Individuals With Skeletal Class III Malocclusions

The aim of this article is to describe a successful clinical protocol for prosthodontic rehabilitation of a patient with a skeletal Class III malocclusion using a fixed-detachable maxillary prosthesis supported by 6 implants and the MK1 attachment system. The patient was followed up for 8 years. A 46-year-old edentulous woman with a skeletal Class III malocclusion expressed dissatisfaction with her old existing maxillary denture from an esthetic point of view and frustration regarding its function. A fixed-detachable maxillary prosthesis using the MK1 attachment system was made. The patient was followed up clinically and radiographically for 8 years. No bone loss, fracture of prosthetic components, or fracture of the prosthesis was detected in that period. A fixed detachable maxillary prosthesis using the MK1 attachment system is a treatment option for patients with Class III malocclusions who opt not to undergo orthognathic surgery.

Implant-retained finger prosthesis with modified retention system

Background: Amputations affect both the physical and the psychological aspects of an individual, causing significant impact on self-esteem. The main causes of finger amputations are work-related accidents with dangerous machinery, road traffic accidents, and animal bites, as well as systemic diseases such as diabetes. This report aims to describe a simple technique for fabrication of implant-retained finger prosthesis with a modified base of the retention system.Case Description and Methods: The O-Ring retention system was used with a modified hexagon-shaped base and a metallic capsule adapted to the acrylic resin to attach the prosthesis to the implant.Findings and Outcomes: The prosthesis was made with silicone, and after osseointegration, it was installed without complications, leading to a patient satisfied with the end result and encouraged to return to social life.

Tooth Discoloration Induced by Endodontic Phenothiazine Dyes in Photodynamic Therapy

Objective: This study sought to assess if discoloration of tooth structures occurs after photodynamic therapy (PDT) and to determine the efficacy of a protocol to remove the photosensitizers. Background data: PDT has been used in root canal treatment to enhance cleaning and disinfection of the root canal system. PDT uses a low power laser in association with a dye as a photosensitizer. Photosensitizers can induce staining of the dental structures, resulting in an unaesthetic appearance. Methods: Forty teeth were randomly divided into four groups according to the photosensitizer used and pre-irradiation time: 0.01% methylene blue for 5 min (MB5); 0.01% methylene blue for 10 min (MB 10); 0.01% toluidine blue for 5 min (TB5); and 0.01% toluidine blue for 10 min (TB 10). Specimens were irradiated with a 660 nm diode laser with a 300 mu m diameter optical fiber, at 40 mW power setting for 3 min. Immediately after, the photosensitizers were removed with Endo-PTC cream +2.5% sodium hypochlorite (NaOCl). The shade was measured by a Vita Easyshade spectrophotometer based on the CIELAB color system (L*a*b* values) at three different experimental times: before PDT (T0), immediately after PDT (T1), and after removal of the photosensitizer (T2). Results: The results showed a decrease in the averages of the L*a*b* coordinate values after PDT (T1) in all the groups, when compared with the number at T0, with a significant statistical difference in group MB10. After photosensitizer removal (T2), all the values of the coordinates increased with significant statistical differences (p < 0.05) between T1 and T2 in L* and a*. Conclusions: It can be concluded that both methylene blue and toluidine blue dyes cause tooth discoloration, and that Endo-PTC cream associated with 2.5% NaOCl effectively remove these dyes, regardless of the pre-irradiation time used for PDT.

Proteins, Pathogens, and Failure at the Composite-Tooth Interface

In the United States, composites accounted for nearly 70% of the 173.2 million composite and amalgam restorations placed in 2006 (Kingman et al., 2012), and it is likely that the use of composite will continue to increase as dentists phase out dental amalgam. This trend is not, however, without consequences. The failure rate of composite restorations is double that of amalgam (Ferracane, 2013). Composite restorations accumulate more biofilm, experience more secondary decay, and require more frequent replacement. In vivo biodegradation of the adhesive bond at the composite-tooth interface is a major contributor to the cascade of events leading to restoration failure. Binding by proteins, particularly gp340, from the salivary pellicle leads to biofilm attachment, which accelerates degradation of the interfacial bond and demineralization of the tooth by recruiting the pioneer bacterium Streptococcus mutans to the surface. Bacterial production of lactic acid lowers the pH of the oral microenvironment, erodes hydroxyapatite in enamel and dentin, and promotes hydrolysis of the adhesive. Secreted esterases further hydrolyze the adhesive polymer, exposing the soft underlying collagenous dentinal matrix and allowing further infiltration by the pathogenic biofilm. Manifold approaches are being pursued to increase the longevity of composite dental restorations based on the major contributing factors responsible for degradation. The key material and biological components and the interactions involved in the destructive processes, including recent advances in understanding the structural and molecular basis of biofilm recruitment, are described in this review. Innovative strategies to mitigate these pathogenic effects and slow deterioration are discussed.

Influence of nanoparticles on color stability, microhardness, and flexural strength of acrylic resins specific for ocular prosthesis

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

BIOMECHANICAL BEHAVIOR OF THE SYSTEM PROSTHESIS/DENTAL IMPLANT: ANALYSIS BY THE PHOTOELASTICITY METHOD

One of the main reasons for the failure in dental implant treatments is the overload, which can cause bone resorption and later, the osseointegration loss in the implant. Therefore, the aim of this study was to analyze the tension generated around dental implants in the rehabilitation of three mandible posterior teeth, varying the connection type, the disposal, and the quantity of implants. The photoelasticity method was used in order to accomplish it. Through photoelasticity, the quantity and localization of the tensions around the implants in the different studied groups were compared (three straight line implants, three offset placement implants, two implants with a mesial cantilever, and two implants with a pontic). The results showed that the tension quantity and disposition around the dental implants of the connection external hexagon and internal hexagon were similar in all groups. In the group where the cantilever was used, an increase of the tension around the implant, adjacent to the cantilever, was observed. From the results it is concluded that the type of connection used in this study did not influence the tension quantity and distribution around the implants; however, the prosthetic configuration with the cantilever use, led to an increase of the tension around the implant, adjacent to the cantilever.

Análise da qualidade de vida de pacientes com a doença de Charcot-Marie-Tooth tipo 1A

A doença de Charcot-Marie-Tooth (CMT) é a mais freqüente das neuropatias hereditárias, mas a sua história natural é pouco conhecida. Apesar da maioria dos pacientes apresentarem uma evolução com características mais “benignas”, é associado à doença com um comprometimento funcional, o que pode ser acompanhado de limitações e incapacitações. O presente estudo teve como objetivo avaliar a qualidade de vida de pacientes afetados pela CMT1A. Considerando que a qualidade de vida pode sofrer influência de variáveis sócio-culturais, um estudo neste contexto mostra-se oportuno. Nenhum estudo de nosso conhecimento realizou tal avaliação no contexto brasileiro. Fizeram parte deste estudo pacientes com CMT decorrente da duplicação 17p11.2-p12 (CMT1A) que foram avaliados quanto ao comprometimento funcional por meio da aplicação do SF-36. Esse questionário é utilizado internacionalmente para aferir a qualidade de vida dos indivíduos. Os resultados obtidos foram submetidos à análise estatística. Como resultados não se observaram associações entre o gênero e os domínios avaliados para a qualidade de vida. Os dados obtidos revelaram que a qualidade de vida dos pacientes com CMT1A se mostrou comprometida principalmente quanto aos seus Aspectos Sociais (p = 0,02) e Aspectos emocionais (p = 0,04). Adicionalmente, houve uma tendência ao comprometimento da Capacidade Funcional (p = 0,08), sendo que os outros índices de avaliação de comprometimento físico se mostraram preservados. A presença ou ausência de ocupação parece influenciar os Aspectos Sociais apresentando uma tendência de diferença significativa (p = 0,07), possuindo o grupo com ocupação valores superiores. Apesar da CMT1A apresentar piora clínica ao longo dos anos, a idade mais avançada não implicou em uma pior percepção da qualidade de vida no grupo de pacientes estudados no presente trabalho... (Resumo completo, clicar acesso eletrônico abaixo)

Saúde bucal do binômio mãe-filho: aspectos clínicos, sócio-comportamentais e qualidade de vida

Pós-graduação em Odontologia Preventiva e Social - FOA

Digital radiography for determination of primary tooth length: in vivo and ex vivo studies

Background. Methods for determining the root canal length of the primary tooth should yield accurate and reproducible results. In vitro studies show some limitations, which do not allow their findings to be directly transferred to a clinical situation. Aim. To compare the accuracy of radiographic tooth length obtained from in vivo digital radiograph with that obtained from ex vivo digital radiograph. Method. Direct digital radiographs of 20 upper primary incisors were performed in teeth (2/3 radicular resorption) that were radiographed by an intraoral sensor, according to the long-cone technique. Teeth were extracted, measured, and mounted in a resin block, and then radiographic template was used to standardise the sensor-target distance (30 cm). The apparent tooth length (APTL) was obtained from the computer screen by means of an electronic ruler accompanying the digital radiography software (CDR 2.0), whereas the actual tooth length (ACTL) was obtained by means of a digital calliper following extraction. Data were compared to the ACTL by variance analysis and Pearson’s correlation test. Results. The values for APTL obtained from in vivo radiography were slightly underestimated, whereas those values obtained from ex vivo were slightly overestimated. No significance was observed between APTL and ACTL. Conclusion. The length of primary teeth estimated by in vivo and ex vivo comparisons using digital radiography was found to be similar to the actual tooth length.

Tratamento ortodôntico da agenesia de incisivo lateral superior com envolvimento de fratura radicular de incisivo central superior

Patients with agenesis of maxillary lateral incisor must have in your planning functional and aesthetic considerations, important to the success of the treatment, regardless of whether the choice of treatment is closing or opening and maintenance of space for rehabilitation with prosthesis. This choice will depend on factors such as skeletal and tooth structure and profile. Children and adolescents are the group of individuals most exposed to trauma and fracture of the maxillary lateral incisor due to the activities they perform. Proper diagnosis and good treatment are essential to the success of the treatment. This article aims to report a case of agenesis of the maxillary lateral incisor along with the involvement of a root fracture of the maxillary central incisor. The orthodontic treatment was successfully finished with a favorable prognosis for the fractured incisor to stay in a esthetic and functional position.