A critical analysis of the degree of conversion of resin-based luting cements

Objective

This study analyzed the degree of conversion (DC%) of four resin-based cements (All Ceram, Enforce, Rely X ARC and Variolink II) activated by two modes (chemical and dual), and evaluated the decrease of DC% in the dual mode promoted by the interposition of a 2.0-mm-thick IPS Empress 2 disc.

Material and Methods

In the chemical activation, the resin-based cements were prepared by mixing equal amounts of base and catalyst pastes. In the dual activation, after mixing, the cements were light-activated at 650 mW/cm² for 40 s. In a third group, the cements were lightactivated through a 2.0-mm-thick IPS Empress 2 disc. The DC% was evaluated in a FT-IR spectrometer equipped with an attenuated total reflectance crystal (ATR). The data were analyzed by two-way ANOVA and Tukey''s HSD test.

Results

For all resin-based cements, the DC% was significantly higher with dual activation, followed by dual activation through IPS Empress 2, and chemical activation (p<0.05). Irrespective of the activation mode, Rely X presented the highest DC% (p<0.05). Chemically activated Variolink and All Ceram showed the worst results (p<0.05). The DC% decreased significantly when activation was performed through a 2.0-mm-thick IPS Empress 2 disc (p<0.05).

Conclusions

The results of the present study suggest that resin-based cements could present low DC% when the materials are dually activated through 2.0 mm of reinforced ceramic materials with translucency equal to or less than that of IPS-Empress 2.     

A rare complication of idiopathic osteosclerosis

Idiopathic osteosclerosis (IO) is described as a localized no expansible radiopacity with unknown etiology. The IO is generally asymptomatic and could appear as round, elliptical or irregular in shape. The internal aspect is usually uniformly radiopaque. IO should be distinguished from condensing osteitis of dental origin, or other alveolar bone related radiopacities such as periapical cemental dysplasia. This condition may cause changes in tooth position or problems during orthodontic treatment. The purpose of the present study is to report a case of tooth resorption caused by ectopic eruption rote caused by IO. This condition represents a rare complication of IO.     

Analysis of the association of polymorphism in the osteoprotegerin gene with susceptibility to chronic kidney disease and periodontitis

Background and Objective:  Chronic kidney disease (CKD) is a complex disorder, which results in several complications involving disturbance of mineral metabolism. Periodontal disease is an infectious disease that appears to be an important cause of systemic inflammation in CKD patients. Periodontal disease is characterized by clinical attachment loss (CAL) caused by alveolar bone resorption around teeth, which may lead to tooth loss. Osteoprotegerin (OPG) is a key regulator of osteoclastogenesis. Polymorphisms are the main source of genetic variation, and single nucleotide polymorphisms (SNPs) have been reported as major modulators of disease susceptibility. The aim of this study was to investigate the association of a polymorphism located at position –223 in the untranslated region of the OPG gene, previously known as –950, with susceptibility to CKD and periodontal disease.
Material and Methods:  A sample of 224 subjects without and with CKD (in hemodialysis) was divided into groups with and without periodontal disease. The OPG polymorphism was analyzed by polymerase chain reaction and restriction fragment length polymorphism.
Results:  No association was found between the studied OPG polymorphism and susceptibility to CKD or periodontal disease.
Conclusion:  It was concluded that polymorphism OPG –223 (C/T) was not associated with CKD and periodontal disease in a Brazilian population. Studies on other polymorphisms in this and other genes of the host response could help to clarify the involvement of bone metabolism mediators in the susceptibility to CKD and periodontal disease.     

Myoepithelial carcinoma of the submandibular gland: report of a case with multiple cutaneous metastases

Myoepithelial carcinoma is a rare and aggressive neoplasm of the salivary glands. One-third of the patients may develop regional distant metastases, and lungs and kidneys have been regarded as the most usual sites for implantation. There is, however, little information on the metastatic behavior of this malignancy. We report the first case of patient with multiple cutaneous metastases from a myoepithelial carcinoma of the submandibular gland, which depicted a very aggressive clinical course.     

The relationship between fibre post geometry and flexural properties: an assessment through a modified three-point bending test

The aim of this study was to investigate the flexural properties of five types of fiber-reinforced dowels using a modified three-point bending test. Fiber-reinforced resin dowels were tested by a modified three-point bending test associated with models for cylindrical and conical simple-supported beams. The fracture load ranged from 86 to 246 N and the flexural strength from 423 to 1192 MPa. FRC Postec had significantly higher flexural strength and fracture loads values. Thus, the present study demonstrated higher flexural strength values for the FRC Postec fibre posts, suggesting that this system would present a better response to the forces of mastication.     

Prevalence and determinant factors of malocclusion in children with special needs

Careful attention to malocclusion in children with special needs leads to a considerable improvement in the quality of life. The present study analysed the prevalence of malocclusion in children with Down syndrome (DS) and cerebral palsy (CP) as well as associations with individual, socio-economic, and behavioural factors. A cross-sectional study was carried out that included 181 mothers and their children with DS and CP (aged 3-12 years) at two institutions for individuals with special needs in Rio de Janeiro, Brazil. Data were collected using a questionnaire administered to the mothers and a dental examination of the children. Clinical examination recorded the following: anterior/posterior crossbite and anterior openbite (AOB). The control variables were the mother's level of education as well as the gender and age of the child. Statistical analysis of the data was performed using the chi-square test and multiple logistic regression. An anterior crossbite was present in 20.4 percent, a posterior crossbite in 21.5 percent, and an AOB in 29.8 percent. The presence of DS, bottle feeding, and non-nutritive sucking habits for 24 months or more was determinant factors for an anterior crossbite and the presence of DS, bottle feeding and non-nutritive sucking habits for 24 months or more, and respiratory infection in the previous 6 months was determinant factors for a posterior crossbite. The presence of CP and non-nutritive sucking habits for 24 months or more was determinant factors for an AOB. Thus, the prevalence of malocclusion in children with special needs was associated with the type of disability, use of bottle feeding and non-nutritive sucking habits for 24 months or more, and respiratory infection in the previous 6 months.     

Investigating Potential Correlations between Endodontic Pathology and Cardiovascular Diseases Using Epidemiological and Genetic Approaches

Introduction

Apical periodontitis (AP) and cardiovascular diseases (CVDs) are chronic conditions triggered by an inflammatory process and sharing similar pathogeneses and molecular players. Previous studies have suggested that AP may perpetuate a systemic inflammation state and, in turn, contribute to CVD. In this study, we investigated the potential association between endodontic pathology and CVD using epidemiological and genetic approaches.

Radiographic diagnosis of incipient proximal caries: an ex-vivo study

The aim of this ex vivo study was to compare visual clinical and radiographic examinations to the histological analysis for proximal caries diagnosis in extracted permanent molars and premolars. The relationship between clinical aspects and carious lesions was also evaluated. Eighty-eight proximal surfaces (44 freshly extracted teeth) were longitudinally sectioned with a 370-microm diamond disk, thinned with wet silicon carbide paper and observed with a stereomicroscope at x40 magnification. Sensitivity and specificity were 65.6% and 83.3% for clinical examination and 29.7% and 95.8% for radiographic examination, respectively. Kappa values ranged from 0.64 to 0.91. The white spots corresponded to lesions restricted to enamel, while the dark spots corresponded to lesions that reached the dentinoenamel junction. In most cases, cavitation corresponded to dentin lesions. It may be concluded that interproximal radiographic examination is not a reliable method for detection of incipient proximal carious lesions.     

Effect of implant diameter on reliability and failure modes of molar crowns

The reliability and failure modes of molar crowns supported by three different implant-supported designs were tested according to the following groups: group 1, one standard-diameter implant (3.75 mm); group 2, one narrow-diameter implant (3 mm); and group 3, two narrow-diameter implants (3 mm). Loads were applied as mouth-motion cycles using a step-stress accelerated life-testing method. ? values for groups 1 and 3 (1.57 and 2.48, respectively) indicated that fatigue accelerated the failure of both groups, but not for group 2 (0.39). Abutment screw failure was the chief failure mode. Strength and reliability were significantly higher for groups 1 and 3 compared to group 2.