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

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

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.

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)

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.

Alternativa de tratamento simplificado e integrado da retenção intraóssea de incisivo central superior, associada a odontoma: relato de caso

Permanent teeth impaction is highly prevalent among brazilian people. Its etiology is related to local and general factors association. Permanent teeth retention compromises dental occlusion and when anterior teeth are involved, it also brings esthetics impairments which lead to psychological disturbance. Early diagnosis and adequate treatment are extremely important to solve not only occlusal problems but also psychological aspects. Orthodontic traction of impacted teeth can be conducted by using fixed or removable appliances. Although it depends on patient compliance the use of removable appliances provides an anchorage based on the teeth and the palate reducing undesirable side effects. This paper describes the case of a fourteen years old female patient whose right maxillary central incisor was adequately tractioned with a removable orthodontic appliance. Removable orthodontic devices were used at first to reposition teeth in maxillary anterior area what provided adequate space to allow the placement of the impacted incisor and after were also used to traction and position this tooth. The procedure described seemed to be effective, non expensive and a viable treatment to be performed even on the scope of public health services, extending orthodontic treatment to a higher number of patients.

Controlling mechanical undesirable side effects with a tooth indicated for extraction: free anchorage

This manuscript describes the use of a tooth indicated for extraction due
to orthodontic reasons as an anchorage aid to receive undesirable side effects caused by orthodontic uprighting of a contralateral molar tooth. The mandibular right second molar was mesially tipped as a result of loss of the adjacent first molar. Since the treatment plan involved extraction of the mandibular left first premolar, undesirable side effects associated with the molar uprighting movement were transferred to this tooth. Once the second molar was vertical, the premolar was extracted and the treatment continued. The results suggest that treatment time can be reduced if undesirable orthodontic mechanical side effects can be directed to a tooth whose extraction is indicated.

Tratamento cirúrgico de canino incluso em mento: relato de caso

The mandibular and maxillary canines when well positioned in the arch, are important functionally and aesthetically. Although these teeth are frequently malpositioned in the dental arch, their absence of eruption are not common, occuring more frequently with the maxillary canine than the mandibular canine. The canine transmigration is a well-known pre eruptive phenomenon in which the tooth goes thru the facial midline, occurring more frequently in the mandible than in maxila. Females are more susceptible than males and the right side more than the left one. Normally the patients do not show any symptoms, and this condition is observed during radiographic exams to diagnose the late exfoliation of the deciduous canine or for any other purpose. Due to the relationship between impacted canines and pathologic lesions, infection, trauma to the adjacent teeth, pain, ectopic eruption and interference with prosthesis, it´s indicated the surgical extraction of these teeth. The goal of this article is to describe and discuss the surgical treatment of an impacted canine (43) in the chin.

Correlation between pH and surface structural changes on human enamel submitted to different tooth whitening agents

The intense valuation of an esthetic pleasant smile guided the dentistry to bleached tooth due the popularity of whitening treatments. The consequence of it is an increasing interest in searching the effect of peroxides in hard dental tissues. The aim of this work was to analyze qualitatively in vitro the human enamel after three different bleaching treatments: Opalescence PF 10%, White Class 7.5% and Opalescence Xtra Boost 38%, correlating the structural changes in the surface of the enamel with its respective pH. A total of 40 sound human pre-molars were randomly divided into four groups of 10 elements, which had been immersed in artificial saliva during all the experiment. Bleaching protocols followed the recommendations of the respective manufacturers. Each bleached sample and control group were submitted to a scanning electronic microscopy analysis and compared with one another. Bleaching agents used in this experiment had modified the morphologic aspect of the surface of the dental enamel; however, it did not have correlation between the degrees of severity of the alterations and pH. There is a correlation between hydrogen peroxide concentration and changes in the enamel, where G4 showed more severe alterations, followed for G3 and G2.

Estudio del espesor de la mucosa del trígono retromolar con el objetivo de facilitar la planificación de mini implantes en la región

The retromolar triangle is a triangular area located in the mandible, posteriorly to the last molar. This region, due its thickness and bone density, is widely used for the installation of devices that provide an anchorage system for the movement of the lower molars. The aim of this research is to provide morphometric data of the mucosa thickness of the retromolar triangle. Twenty-five patients of portuguese nationality, with indication for extraction of the impacted lower third molar (right and/or left), were studied. In the region of the retromolar triangle were demarcated 3 points corresponding to the vertices of a triangle whose the base was torned for the distal face of the lower third molar and the lenght of the sides corresponded to vestibulolingual dimension of the same tooth, then was demarcated a fourth point corresponding to the geometric center of the triangle. Then, using a finger spreader with silicone stop were measured the mucosal tickness at each point. The data obtained were tabulated and analyzed. The lowest average value found was 5.5mm on the right side and the highest average value found was 7.13mm on the left side. Considering the mean values obtained at the points of the retromolar triangle mucosa measured in this study, we conclude that the retromolar triangle shows thick mucosa, so the mini-implants indicated for this region should have a long transmucosal neck.

Effect of two formulations of 10% sodium ascorbate on fracture resistance of endodontically treated tooth submitted to dental bleaching with hydrogen peroxide associated titanium dioxide nanoparticles

Purpose: This study evaluated the effect of 10% sodium ascorbate (10SA), in gel (10SAg) or aqueous solution (10SAs) formulations, on fracture resistance of endodontically treated tooth submitted to dental bleaching procedures with 15% hydrogen peroxide associated with titanium dioxide (15HP-TiO2) nanoparticles and photoactivated by LED-laser. Material and methods: Forty maxillary premolars were endodontically-treated and embedded in acrylic resin up to the cement-enamel junction. The specimens were divided into four groups (n=10): G1 (negative control): no bleaching, coronal access restored with composite resin; G2 (positive control): three dental bleaching sessions using 15HP-TiO2 and LED-laser photoactivation and restored with composite resin (positive control); G3 (10SAg): similar procedures to G2, but applied 10SA, in gel formulation, for 24 hours before restoration; G4 (10SAs): similar procedures to G3, but applied 10SA, in aqueous solution formulation. The 15HP-TiO2 was applied on buccal and lingual surfaces of the crown tooth and inside the pulp chamber and photoactivated by LED-laser. Between each bleaching session, the teeth were maintained in artificial saliva, at 37oC, for 7 days. In sequence, the teeth were submitted to fracture resistance testing using an eletromechanical machine test. The data was analyzed using Kruskal Wallis test (p = 0.05) Results: There are no differences significant among the groups in relation to fracture resistance of endodontically treated teeth (p>0.05). Conclusions: The use of 10% sodium ascorbate, in gel or aqueous solution formulations, did not interfered on the fracture resistance teeth after dental bleaching using 15HP-TiO2 and LED-laser photoactivation.

Effect of alendronate sodium on tooth movement in ovariectomized rats

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Evaluation of the genotoxicity of waters impacted by domestic and industrial effluents of a highly industrialized region of So Paulo State, Brazil, by the comet assay in HTC cells

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Bonding ability of paste-paste glass ionomer systems to tooth structure: in vitro studies

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)