Effects of a calcium phosphate cement on mineralized nodule formation compared with endodontic cements.

The aim of this study was to investigate mineralizing ability of a premixed calcium phosphate cement (premixed-CPC) compared to mineral trioxide aggregate (MTA) and zinc oxide eugenol cement (SuperEBA) in ROS17/2.8 cells. The measurements of cell proliferation, alkaline phosphatase (ALPase) activity and mineralized nodule formation in the presence or absence (control) of the test materials were performed using a cell culture insert method with the test materials placed on a porous membrane of culture plate insert. Mineralized nodules were detected by staining with alizarin red, and the calcium content of the mineralized nodules was determined quantitatively using a calcium assay kit. Premixed-CPC and MTA indicated significantly higher cell proliferation, ALPase activity, mineralized nodule formation, and calcium content in nodules than those of SuperEBA (p<0.05). The present results suggest that premixed-CPC has the same mineralizing ability as MTA.

A no-contact vibration device for measuring implant stability.

OBJECTIVES: Monitoring implant stability is an important factor in determining the long-term success rate of implants. Periotest values and resonance frequency analysis have been widely used for this purpose, but these indicators mainly reflect the mobility and/or stability of implants. Thus, a no-contact electromagnetic vibration device was developed and tested for monitoring both tooth mobility and periodontal tissue conditions. The aim of this study was to evaluate the ability of a no-contact electromagnetic vibration device to measure implant stability under various peri-implant conditions using mechanical parameters. MATERIAL AND METHODS: The device consisted of three components: the vibrator, detector, and analyzer. The mechanical parameters resonant frequency, elastic modulus, and coefficient of viscosity were used to measure simulated atrophic bone defects in periodontal tissues. RESULTS: The resonant frequency and the elastic modulus increased with an increase in supporting bone height. In contrast, the coefficient of viscosity decreased with bone height. Values for the three parameters for the formed urethane models were lower than those for the urethane models. CONCLUSIONS: A no-contact electromagnetic vibration device may be capable of monitoring implant stability, and mechanical parameters may be useful for assessing the condition of periodontal tissues around implants.

In Vitro and in Vivo Characteristics of Fluorapatite-Forming Calcium Phosphate Cements.

This study reports for the first time in vitro and in vivo properties of fluorapatite (FA)-forming calcium phosphate cements (CPCs). The experimental cements contained from (0 to 3.1) mass % of F, corresponding to presence of FA at levels of approximately (0 to 87) mass %. The crystallinity of the apatitic cement product increased greatly with the FA content. When implanted subcutaneously in rats, the in vivo resorption rate decreased significantly with increasing FA content. The cement with the highest FA content was not resorbed in soft tissue, making it the first known biocompatible and bioinert CPC. These bioinert CPCs might be useful for applications where slow or no resorption of the implant is required to achieve the desired clinical outcome.

Endodontic treatment of bilateral dens evaginatus premolars with large periapical lesions.

Dens evaginatus is a developmental anomaly characterized by the presence of an accessory cusp composed of enamel and dentine, usually containing pulp tissue. This condition is clinically important because of fracture or wear of the tubercle, which can frequently lead to the major complication of pulp necrosis and periapical infection. Treatment varies according to pulp condition, tubercle integrity, and stage of root development. Here we report a case of bilateral dens evaginatus with large periapical lesions. Non-surgical root canal treatment using calcium hydroxide medication was performed for both mandibular second premolars. At the 3-year postoperative recall examination, the teeth were asymptomatic and radiographically showed healing of the periapical lesions.

A 52-week repeated dose toxicity study of ultraviolet absorber 2-(2'-hydroxy-3',5'-di-tert-butylphenyl)benzotriazole in rats.

A 52-week repeated dose toxicity study of an ultraviolet absorber, 2-(2'-hydroxy-3',5' -di-tert-butylphenyl)benzotriazole (HDBB), was conducted according to OECD TG 452 under GLP. CD(SD)IGS rats were given HDBB by gavage at 0, 0.1, 0.5, or 2.5 mg/kg/day in males and 0, 0.5, 2.5, or 12.5 mg/kg/day in females. No substance-related deaths or clinical signs of toxicity were observed in any group; however, a lowered body weight was found from day 36 to the end of the 52-week administration period at 2.5 mg/kg in males. At the completion of the dosing period, a decrease in red blood cells at 0.5 mg/kg and higher, and in hematocrit at 2.5 mg/kg, was detected in males. Blood biochemical changes, including increases in the levels of alkaline phosphatase and glucose and the A/G ratio, were also found at 0.5 mg/kg and higher in males and at 12.5 mg/kg in females. At necropsy, absolute and relative liver weight was increased at 0.5 mg/kg and higher in males and at 12.5 mg/kg in females. Histopathological changes were observed in the liver; centrilobular hypertrophy of hepatocytes at 0.5 mg/kg and higher in males, and at 12.5 mg/kg in females, and altered hepatocellular foci at 0.5 mg/kg and higher, and cystic degeneration and lipofuscin deposition in hepatocytes at 2.5 mg/kg in males. Based on these findings, the no observed adverse effect level was concluded to be 0.1 mg/kg/day in male rats and 2.5 mg/kg/day in female rats.

Susceptibility of newborn rats to hepatotoxicity of 1,3-dibromopropane and 1,1,2,2-tetrabromoethane, compared with young rats.

Newborn rat studies were conducted with oral administration of 1,3-dibromopropane (DBP) and 1,1,2,2-tetrabromoethane (TBE) from postnatal Days 4 to 21 to allow comparison of NOAELs and unequivocally toxic levels with those from 28-day young rat studies starting at 5-6 weeks of age. The unequivocally toxic level was estimated by our specified criteria, requiring simultaneous change of organ weights, histopathology, some biochemical parameters and body weights, because in this study only hypertrophy of hepatocytes was observed as a major histopathological change. DBP caused centrilobular hypertrophy of hepatocytes with alteration in biochemical parameters, as well as lowering of body weights, regardless of sex, in both newborn and young rats. NOAELs and unequivocally toxic levels were considered to be 50 and 150 mg/kg/day in newborn rats and 10 and 250 mg/kg/day in young rats, respectively. In the newborn rat study of TBE, some hepatic effects observed at the top dose of 50 mg/kg were not considered adverse because of the lack of histopathological changes. Significant lowering of body weight was noted at 200 mg/kg in the dose-finding study but histopathological data were not available. In the young rat study, there was no definite toxicity at 6 mg/kg and hypertrophic changes in liver and thyroids without body weight change occurred at 200 mg/kg. There were no clear sex differences in both the newborn and young rat studies. NOAELs were considered to be 50 and 6 mg/kg/day in newborn and young rats, respectively, but unequivocally toxic levels for both rats could not be estimated. Abnormalities of external and sexual development and reflex ontogeny in the newborn were not observed with either chemical. Based on these results, it can be concluded that the target organ of DBP and TBE is the liver in both newborn and young rats, and that while the doses at which toxic signs began to appear are higher in newborn rats, those causing clear toxicity may be paradoxically lower in the newborn case.

Comparative toxicity study of 2,4,6-trinitrophenol (picric acid) in newborn and young rats.

The toxicity of oral 2,4,6-trinitrophenol (TNP) was determined in newborn rats, and compared with that in young rats. In newborn rats, males and females were given TNP at 0, 16.3, 81.4 or 407 mg/kg per day on postnatal days (PND) 4-17 for the dose-finding study, and at 0, 4.1, 16.3 or 65.1 mg/kg per day on PND 4-21 for the main study. Deaths, lower body weight (BW) and behavioral changes were found at 81.4 and 407 mg/kg per day in the dose-finding study, and lower BW was observed in males at 65.1 mg/kg per day during the dosing period of the main study. In young rats, 5-week-old males and females were given TNP at 0, 20, 100 or 500 mg/kg per day for 14 days as the dose-finding study and at 0, 4, 20 or 100 mg/kg per day for 28 days as the main study. Deaths were observed at 500 mg/kg per day in the dose-finding study. Deaths or changes in BW were not found at 100 mg/kg per day or less. At 100 mg/kg per day, hemolytic anemia and testicular toxicity were found. In conclusion, toxicity profiles induced by TNP were markedly different between newborn and young rats.