Differential bonds degradation of two resin-modified glass-ionomer cements in primary and permanent teeth

Objectives: To evaluate the effect of chemical degradation on bond strength of resin-modified glass-ionomer cements bonded to primary and permanent dentin. Methods: Class I cavities of permanent and primary extracted human molars were restored with two resin-modified glass-ionomer cements: Fuji 11 LC and Vitremer, and stored in water for 24 h. Half samples were immersed in 10% NaOCl aqueous solution for 5 h. Teeth were sectioned into beams and tested for microtensile bond strengths. Results were analyzed with multiple ANOVA and Tukey`s tests (p < 0.05). Analysis of debonded surfaces was performed by SEM. Results: 24 h bond strengths for Vitremer and Fuji 11 LC were similar. For Fuji 11, bond strength values were higher for primary than for permanent dentin. Vitremer bond strength was similar for both. Chemical degradation did not affect Fuji I] LC bond strength to dentin. However, decreases in bond strength were found for Vitremer groups after NaOCl immersion. Signs of glass ionomer-dentin interaction were evident by SEM analysis for Fuji 11 LC specimens. Conclusions: Vitremer and Fuji II presented similar bond strength at 24. Vitremer dentin bonds were prone to chemical degradation. Fuji II LC-dentin bonds showed typical features of glass-ionomer dentin interaction at the bonded interfaces, and were resistant to in vitro degradation. (C) 2009 Elsevier Ltd. All rights reserved.

Pulpotomy of human primary molars with MTA and Portland cement: a randomised controlled trial

Objective This study compared the clinical and radiographic effectiveness of mineral trioxide aggregate (MTA) and Portland cement (PC) as pulp dressing agents in carious primary teeth. Methodology Thirty carious primary mandibular molars of children aged 5-9 years old were randomly assigned to MTA or PC groups, and treated by a conventional pulpotomy technique. The teeth were restored with resin modified glass ionomer cement. Clinical and radiographic successes and failures were recorded at 6, 12, 18 and 24-month follow-up. Results All pulpotomised teeth were clinically and radiographically successful at all follow-up appointments. Six out of 15 teeth in the PC group and five out of 14 teeth in the MTA group exfoliated throughout the follow-up period. No statistically significant difference regarding dentine bridge formation was found between both groups throughout the follow-up period. As far as pulp canal obliteration is concerned, a statistically significant difference was detected at 6-month follow-up (p < 0.05), since the beginning of mineralised material deposition could be radiographically detected in 100% and 57.14% of the teeth treated with PC and MTA, respectively. Conclusions PC may serve as an effective and less expensive MTA substitute in primary molar pulpotomies. Further studies and longer follow-up assessments are needed.

Replantation of an avulsed maxillary primary central incisor and management of dilaceration as a sequel on the permanent successor

This case report outlines the sequel and possible management of a permanent tooth traumatized through the predecessor, a maxillary right primary central incisor that was avulsed and replanted by a dentist 1 h after the trauma in a 3-year-old girl. Three years later, discoloration and fistula were present, so the primary tooth was extracted. The patient did not come to the scheduled follow-ups to perform a clinical and radiographic control of the succeeding permanent incisor, and only returned when she was 10 years old. At that moment, the impaction and dilaceration of the maxillary right permanent central incisor were observed through radiographic examination. The dilacerated permanent tooth was then surgically removed, and an esthetic fixed appliance was constructed with the crown of the extracted tooth. Positive psychological influence of the treatment on this patient was also observed.

The effectiveness of mineral trioxide aggregate, calcium hydroxide and formocresol for pulpotomies in primary teeth

Aim To compare the effectiveness of mineral trioxide aggregate (MTA), calcium hydroxide (CH) and formocresol (FC) as pulp dressing agents in carious primary teeth. Methodology Forty-five primary mandibular molars with dental caries in 23 children [AUTHOR QUERY: How many children?] between 5 and 9 years old were treated by a conventional pulpotomy technique. The teeth were randomly assigned to the experimental ( CH or MTA) or control ( FC) groups. After coronal pulp removal and haemostasis, remaining pulp tissue was covered with MTA paste or CH powder in the experimental groups. In the control group, diluted FC was placed with a cotton pellet over the pulp tissue for 5 min and removed; the pulp tissue was then covered with zinc oxide-eugenol (ZOE) paste. All teeth were restored with reinforced ZOE base and resin modified glass-ionomer cement. Clinical and radiographic successes and failures were recorded at 3, 6, 12, 18 and 24 month follow-up. Results Forty-three teeth were available for follow-up. In the FC and MTA groups, 100% of the available teeth were clinically and radiographically successful at all follow-up appointments; dentine bridge formation could be detected in 29% of the teeth treated with MTA. In the CH group, 64% of the teeth presented clinical and radiographic failures detected throughout the follow-up period, and internal resorption was a frequent radiographic finding. Conclusions Mineral trioxide aggregate was superior to CH and equally as effective as FC as a pulpotomy dressing in primary mandibular molars. Internal resorption was the most common radiographic finding up to 24 month after pulpotomies performed with CH.

X-ray fluorescence with synchrotron radiation to elemental analysis of lead and calcium content of primary teeth

Primary teeth were analyzed by micro-SRXRF. The aim of this study was to determine the elemental distribution of lead and calcium in different regions of primary incisor of children living in a notoriously contaminated area (Santo Amaro da Purificacao, Bahia State, Brazil). The measurements were performed in standard geometry of 45 incidence, exciting with a white beam and using a conventional system collimation (orthogonal slits) in the XRF beamline at the Synchrotron Light National Laboratory (Campinas, Brazil). (C) 2009 Elsevier Ltd. All rights reserved.

Analysis of enamel microbiopsies in shed primary teeth by Scanning Electron Microscopy (SEM) and Polarizing Microscopy (PM)

The aims of this study were 1) to verify how close to the theoretically presumed areas are the areas of enamel microbiopsies carried out in vivo or in exfoliated teeth; 2) to test whether the etching solution penetrates beyond the tape borders: 3) to test whether the etching solution demineralizes the enamel in depth. 24 shed upper primary central incisors were randomly divided into two groups: the Rehydrated Teeth Group and the Dry Teeth Group. An enamel microbiopsy was performed, and the enamel microbiopsies were then analyzed by Scanning Electron Microscopy (SEMI) and Polarizing Microscopy (PM). Quantitative birefringence measurements were performed. The ""true"" etched area was determined by measuring the etched enamel using the NIH Image analysis program. Enamel birefringence was compared using the paired t test. There was a statistically significant difference when the etched areas in the Rehydrated teeth were compared with those of the Dry teeth (p = 0.04). The etched areas varied from -11.6% to 73.5% of the presumed area in the Rehydrated teeth, and from 6.6% to 61.3% in the Dry teeth. The mean percentage of variation in each group could be used as a correction factor for the etched area. Analysis of PM pictures shows no evidence of in-depth enamel demineralization by the etching solution. No statistically significant differences in enamel birefringence were observed between values underneath and outside the microbiopsy area in the same tooth, showing that no mineral loss occurred below the enamel superficial layer. Our data showed no evidence of in-depth enamel demineralization by the etching solution used in the enamel microbiopsy proposed for primary enamel. This study also showed a variation in the measured diameter of the enamel microbiopsy in nineteen teeth out of twenty four, indicating that in most cases the etching solution penetrated beyond the tape borders. (C) 2009 Elsevier B.V. All rights reserved.

International market selection: Developing a model from Australian case studies

This paper develops a theory that firms seek out new country markets on the basis of expected commercial returns. These expectations depend on judgements about the attractiveness of the market and the firm's competitive position in it, which in turn are influenced by informants. It is the number and strengths of these informants that will underlie the probability of a country being identified and assessed as a new market by any firm.

Familial varieties of primary aldosteronism

1. Improved approaches to screening and diagnosis have revealed primary aldosteronism (PAL) to be much more common than previously thought, with most patients normokalaemic. The spectrum of this disorder has been further broadened by the study of familial varieties. 2. Familial hyperaldosteronism type I (FH-I) is a glucocorticoid-remediable form of PAL caused by the inheritance of an adrenocorticotrophic hormone (ACTH)- regulated, hybrid CYP11B1/CYP11B2 gene. Diagnosis has been greatly facilitated by the advent of genetic testing. The severity of hypertension varies widely in FH-I, even among members of the same family, and has demonstrated relationships with gender, degree of biochemical disturbance and hybrid gene crossover point position. Hormone day curve studies show that the hybrid gene dominates over wild-type CYP11B2 in terms of aldosterone regulation. This may be due, in part, to a defect in wild-type CYP11B2-induced aldosterone production. Control of hypertension in FH-I requires only partial suppression of ACTH and much smaller glucocorticoid doses than previously recommended. 3. Familial hyperaldosteronism type II (FH-II) is not glucocorticoid remediable and is not associated with the hybrid gene mutation. Familial hyperaldosteronism type II is clinically, biochemically and morphologically indistinguishable from apparently non-familial PAL. Linkage studies in one informative family did not show segregation of FH-II with the CYP11B2, AT1 or MEN1 genes, but a genome-wide search has revealed linkage with a locus in chromosome 7. As has already occurred in FH-I, elucidation of causative mutations is likely to facilitate earlier detection of PAL.

Prevalence and diagnostic workup of primary aldosteronism: new knowledge and new approaches

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