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[Uses of MTA, a review. Part 2: Clinical applications].

Mineral trioxide aggregate (MTA) has been used in dentistry for the last five to eight years. Because of its high biocompatibility, its good sealing ability, and the fact that cemental tissues grow on this material, it has a relatively wide range of applications in endodontics. MTA may be used to cap exposed vital pulps, to seal open apices or perforations, or as a retro-filling material in apical surgery. These applications are presented in the current article, and discussed based on case reports.

Aluminum Compounds↗

Current concepts in vital pulpotomies in primary teeth.

Vital pulpotomies in primary teeth are performed to maintain the vitality of the pulp and to hold the tooth until it can be normally exfoliated. There exists much controversy surrounding the issue of pulpotomy agents, and the ideal pulp dressing material has not yet been identified. Therefore, it seems that formocresol will still be the first choice for pulpotomies in primary teeth until such agent is identified.

Aluminum Compounds↗

Mechanical property characterization of a novel directly-placed ceramic restorative material.

PURPOSE: To compare, in vitro, the mechanical properties of a directly-placed ceramic restorative material (Doxadent) to glass-ionomer (Fuji IX), hybrid composite control (Z250) and amalgam control (Tytin). METHODS: Diametral tensile strength (DTS), compressive strength (CS), and Vickers hardness number (VHN) were measured for 10 specimens per group (n = 480 total) with time (1 hour, 24 hours, 1 week, 4 weeks). CS and DTS specimens were cylinders (4 x 8 mm). VHN specimens were disks (9.5 x 1 mm). Specimens were prepared following manufacturers' instructions, stored in deionized water (37 degrees C), and tested in 100% humidity (23 degrees C). CS and DTS specimens were loaded to failure (Instron, CHS = 0.5 mm/minute). VHN discs were indented. Data were analyzed using ANOVAand Tukey's test (P < 0.05) for pairwise comparisons of group means at each time. RESULTS: In CS and DTS, DoxaDent was weakest (P < 0.05) for all testing times except Fuji IX DTS at 1- and 4-week intervals. For VHN, DoxaDent was harder than glass-ionomer, better than composite except at 1 hour and less than amalgam. Except for VHN for Z250, all values improved from 1-24 hours. Based on current in vitro results, this novel restorative material does not yet equal composite or amalgam CS or DTS.

Aluminum Compounds↗

[Effects of different form calcium on growth and tissue calcium level in rats].

In order to solve the problem of calcium deficiency and to look for economic and efficient source of calcium, the effects of calcium carbonate, active calcium and calcium lactate on growth, development and tissue calcium level in rats were compared. Fifty-six 3-week old weaning rats were fed with calcium deficient diet (containing vitamin D 500 IU per kg diet) for 3 weeks, and then were divided into four groups randomly with 14 rats in each group, half male and half female. The diet of control group (A) was the basic diet, while the three experiment diets were supplemented with calcium carbonate (B), active calcium (C) and calcium lactate (D) (3000 mg calcium per kg diet), respectively. The experiment term was 12 weeks. The results showed that the body weight and length of calcium supplemented group were significantly higher than that of control group (P<0.05). Among the calcium supplemented groups, no significant differences were observed except the difference of body length between the group D and the group A in female. Calcium deficiency dramatically hindered the development with reduced dietary intake and decreased food consumption efficiency. The calcium levels in plasma, red blood cells and liver were significantly higher in the supplemented groups than that in the control group (P<0.05), however, there was no difference among the supplemented groups. No significant difference of calcium levels in muscle and heart was observed among all groups. Based on needs for reaching the RDA with additional 400 mg/d from present calcium status in Chinese population, the calcium carbonate is the most economic one and the ideal calcium source for supplementation.

Animals↗

Long-term evaluation of pulpotomy in primary molars using mineral trioxide aggregate or formocresol.

PURPOSE: The objective of this study was to assess the effect of mineral trioxide aggregate (MTA) as pulp dressing material following pulpotomy in primary molars with carious pulp exposure and compare them to those of formocresol (FC). METHODS: Of 33 children, primary molars treated via a conventional pulpotomy technique were randomly assigned to the MTA group (33 teeth) or FC group (29 teeth). Clinical and radiographic follow-up ranged between 4 and 74 months. The mean follow-up time was 38 months, with no difference between the groups. Twenty-nine teeth were followed until uneventful shedding (mean=33 months). Failures were detected after a mean period of 16 months (range=4 to 30). RESULTS: The success rate of pulpotomy was 97% for MTA (1 failure) and 83% for FC (5 failures). Eight teeth presented internal resorption. In 4 of them (2 of each group), progress of the resorption process stopped and the pulp tissue was replaced by a radioopaque calcified tissue. Pulp canal obliteration was observed in 58% of the MTA group and in 52% of the FC group (total=55%). CONCLUSIONS: MTA showed a higher (though not statistically significant) long-term clinical and radiographic success rate than formocresol, and can be recommended as its replacement as, unlike FC, MTA does not induce undesirable responses.

Aluminum Compounds↗

[Luminescence properties and spectral analysis of long phosphorescent phosphors: Ba(1 - x) Ca (x) Al2O4 : Eu2+, RE3+].

New long phosphorescent phosphors Ba(1 -x),Ca(x)Al2O4 : Eu2+, RE3+ (RE3+ = Dy3+, Nd3+) with tunable color emission have been prepared by solid state reaction. The luminescence properties of the samples are discussed and analyzed. The emission spectra show that the tuning range of the color emission of the phosphors is between 498 and 440 nm, which is determined by x, under the excitation of UV. The wavelength of afterglow increases with increasing x until x equals 0.6, and when x equals 0.6, the luminescence property of Ba(1-x) Ca(x)Al2O4: Eu2+, RE3+ (RE3+ = Dy3+, Nd3+) is similar to that of CaAl2O4 : Eu2+, RE3+. The XRD measurements were performed to investigate the single phase states of the samples, and it was found that the single phase limit in the phosphors is below an x value of 0.4. The thermoluminescence curves imply that the traps in the hosts are different with different x value, which well explains the varying delay time of the samples.

Aluminum Oxide↗

Dentin bridge formation after mineral trioxide aggregate (MTA) pulpotomies in primary teeth.

PURPOSE: To evaluate the results of using mineral trioxide aggregate (MTA) in pulpotomy procedures in primary teeth. METHODS: Seven patients were selected and a total of 20 molars and two canines were treated with pulpotomy procedures using MTA instead of formocresol. RESULTS: After 6 months, 55% of the molars and 100% of the canines treated showed radiographic signs of dentin bridge formation. Also, 6 months after treatment, 60% of the molars showed root canal calcification (obliteration). Color change of the crown of the canines treated was noticeable. No clinical or radiographic signs of pathology was observed.

Aluminum Compounds↗

[Preparation and properties of calcium silicate-phosphate composite bone cements].

In this paper, alpha-tricalcium phosphate (alpha-TCP) and tetracalcium phosphate (TTCP) respectively were chosen as basic compositions of phosphate bone cements. Other auxiliary materials such as hydroxyapatite (HAP), dicalcium phosphate dihydrate (DCPD), calcium carbonate (CaCO3), calcium oxide (CaO) and amorphous calcium silicate (CaSiO3) were added in the cements. Six kinds of composite bone cements were decided with 1.50 as their Ca/P ratio. Then the primary properties of them were studied. Ringer's simulated body fluid (SBF) tests were carried out for the samples. The changes of pH value in SBF and the compressive strength of the samples with the immersion time were studied. The results showed: the mixing liquid 0.25 M K2HPO4/KH2PO4 and amorphous CaSiO3 were effective for accelerating the setting of the cements; the initial setting time (It) was about 4-5.5 min and the final setting time (Ft) was about 18-19. 5 min. Amorphous calcium silicate can increase the compressive strength of the bone cements remarkably; the compressive strength of the alpha-TCP bone cement with the addition of suitable amount amorphous CaSiO3 reached 45.3 MPa after immersion in SBF for 14 days.

Bone Cements↗

Dentin bridge formation after white mineral trioxide aggregate (white MTA) pulpotomies in primary molars.

PURPOSE: To evaluate, clinically and radiographically, the dentin bridge formation potential of white mineral trioxide aggregate (white MTA) when used in pulpotomy treatments in primary molars. METHODS: A total of 23 primary molars received a pulpotomy treatment using white MTA followed by stainless steel crown restoration and controlled 6 months after treatment. RESULTS: Clinical and radiographic success was 100% as none of the molars showed any clinical or radiographic pathological signs. Reparative dentin deposition was found in some of the cases: stenosis was present in 69.2% of the pulp canals from mandibular molars and formation of dentin bridges was seen in 11.5% of the pulp canals from mandibular molars 6 months after treatment with white MTA.

Aluminum Compounds↗

Persistent sinus tract formation 1 year following cast post-and-core replacements: a case report.

Sinus tracts are paths of drainage for abscesses and can occur both intraorally and extraorally. It is a fact that sinus tracts can heal with proper endodontic therapy. However, there are those types that are persistent and will not respond to any treatment. In these perplexing cases, it may be necessary to elevate a surgical flap to unveil the real etiologic factor. In this article, a case is presented in which 2 persistent and nonhealing sinus tracts were observed around the maxillary left incisor area of a 53-year-old female patient. A difficult cast post-and-core removal had been accomplished to the compromised tooth 1 year previously. A surgical flap had to be reflected, and the cause of the persistent inflammation was determined to be 2 separate root perforations. The granulation tissue was removed, the perforations were sealed with mineral trioxide aggregate, and bone graft was packed in the resorptive bone areas. The symptoms subsided by the time of the 2-week recall. No complaints were noted from the patient during the 4-month follow-up period. This case is a good example that demonstrates the possible complications of post preparation and the necessity of explorative surgery for unveiling the etiologic factor of persistent sinus tract formation.

Aluminum Compounds↗

[Development and laboratory analysis of new remineralizing means].

In laboratory research there were studied different combinations of remineralizing agents allowing production of substances close by chemical composition to hydroxyapatite of hard dental tissues. The most acceptable for practical use in case of demineralizing foci of hard dental tissues treatment can be only 2 calcium orthophosphates that may be synthesized under physiological conditions from solutions of calcium nitrate and twice-substituted ammonium phosphate, in particular, dicalcium phosphate dihydrate (structure of brushite, CaHP0(4) x 2H(2)O) and the so called precipitated hydroxyapatite (Ca(10-x) (HPO(4))(x)(PO(4))(6-x)(OH)(2-x)). The data are the bases for development of remineralizing agents and their further experimental and clinical studies.

Biocompatible Materials↗