Structural changes induced by tetracycline in secretory ameloblasts in young rats

Effects of Amoxicillin on the Structure and Mineralization of Dental Enamel and Dentin in Wistar Rats

Objectives:

The development of teeth is affected by genetic and environmental factors. Amoxicillin is a widely prescribed semi-synthetic antibiotic. Its most frequent side effects are gastrointestinal disorders and hypersensitivity reactions. The purpose of this study was to determine the effect produced by amoxicillin administration on dental enamel and dentin in Wistar rats.

Materials and Methods:

Twelve pregnant adult Wistar rats were equally divided into four different groups. Negative controls were prescribed with a saline solution. Positive controls were prescribed with tetracycline (130 mg/kg). The other two groups were treated with amoxicillin doses of 50 and 100 mg/kg (every 8 hours), respectively. The treatments were daily administered by oral gavage from the 13th gestation day to the end of gestation. After birth, the offspring also received the same treatment as their mothers from day one to day twelve. After 24 hours, the newborns were sacrificed, the jaws were dissected, and the first molar teeth were collected. The samples were fixed in 10% formaldehyde solution and were histomorphologically and histopathologically observed to determine enamel and dentin abnormalities.

Results:

The mean ameloblastic layer thickness, enamel thickness, odontoblastic layer thickness, and dentin thickness were significantly different in the tetracycline group and the amoxicillin 50 and 100 mg/kg groups compared to the control group. Also, dentin hypomineralization and vacuolization of the odontoblastic layer were observed in the tetracycline- and amoxicillin-treated groups.

Conclusion:

This study showed that amoxicillin interferes with amelogenesis and dentinogenesis and reduces enamel and dentin thickness.

Nonproliferative and Proliferative Lesions of the Rat and Mouse Skeletal Tissues (Bones, Joints, and Teeth)

The INHAND (International Harmonization of Nomenclature and Diagnostic Criteria for Lesions in Rats and Mice) Project (www.toxpath.org/inhand.asp) is an initiative of the Societies of Toxicological Pathology from Europe (ESTP), Great Britain (BSTP), Japan (JSTP) and North America (STP) to develop an internationally accepted nomenclature for proliferative and nonproliferative lesions in laboratory animals. The purpose of this publication is to provide a standardized nomenclature for classifying microscopic lesions observed in the skeletal tissues and teeth of laboratory rats and mice, with color photomicrographs illustrating examples of many common lesions. The standardized nomenclature presented in this document is also available on the internet (http://www.goreni.org/). Sources of material were databases from government, academic and industrial laboratories throughout the world.

Effects of a Macrolide Antibiotic on Enamel Formation in Rat Incisors-Primary Lesion of Ameloblast at the Transition Stage

A novel macrolide antibiotic was administered orally to 5-week-old Jcl:Wistar rats at a dose of 5,000 mg/kg/day for 5 weeks, and then a half of animals were maintained without any treatment for 10 weeks. A white discolored lesion with horizontal stripes developed on the surface of the upper and lower incisors after dosing for 4 weeks, and these macroscopical incisal lesions disappeared with the eruption in 4 weeks after stop of administration. Histopathologically, increase in number of karyopycnosis of ameloblast at the transitional stage, vacuolar degeneration of ameloblast and cystic change in the maturation stage, and impaired iron pigment secretion at the pigmentation stage were observed. Microradiography, calcio-traumatic zones, which means hypocalcification, were observed on the superficial layer of enamel. These results suggest that the primary lesion induced by a novel macrolide antibiotic is the increased karyopycnosis of ameloblast at the transitional stage, and followed by later stage.

Fluoride toxicity: a biochemical and scanning electron microscopic study of enamel surface of rabbit teeth

The present study has been carried out to investigate the effect of fluoride toxicity on the morphology as well as inorganic chemical constituents of rabbit teeth. Rabbits were administered sodium fluoride at a dose of 10 mg NaF/kg body weight every 24 h for 18 and 23 months. The incisor and molar teeth (whole tooth) were investigated for fluoride, calcium and phosphorus content in 18- and 23-month treated animals. The enamel surfaces of incisor teeth of 23-month treated animals were examined under scanning electron microscope. A significant increase in fluoride levels and significant decrease in calcium content was found following fluoride administration for 18 and 23 months as compared to control. Ca/P ratio was significantly increased only in 23-month treated animals. The scanning electron micrographs revealed hypoplastic, rough, uneven, pitted and cracked enamel surfaces covered with granular deposits as a result of excessive intake of fluoride. It can be concluded that long term fluoride administration leads to severe structural alterations on the enamel surface, possibly through defective mineralization.