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

How prenatal environmental factors affect rat molar enamel formation?

Amelogenin (AMELX) and ameloblastin (AMBN) are crucial for enamel formation, and interruptions in the production of these proteins may cause enamel defects. We investigated how prenatal environmental factors (chronic stress, bisphenol A (BPA), amoxicillin, and lipopolysaccharide (LPS)) affect AMELX and AMBN production of ameloblasts. Fifteen pregnant Sprague-Dawley rats were divided into four experimental groups and a control group. Chronic-stress group rats were exposed to a 12:12 light/light cycle (LL) from day E18 until delivery. BPA group rats were orally administered 5 μg/kg BPA daily from day E1 until delivery. Amoxicillin group rats were injected 100 mg/kg amoxicillin daily from day E18 until delivery. LPS-infection group rats were injected 125 μg/kg bacterial LPS once on day E18. Seven pups from the control group and ten pups from the experimental groups were euthanized on P10. Sections were stained with hematoxylin and eosin (H&E) and Gomori's one-step trichrome staining (GT) and incubated with rabbit polyclonal antibodies to AMELX and AMBN, to evaluate staining intensity at ameloblast stages. The surface morphology was evaluated with a stereomicroscope. AMELX (p = 0.008, p = 0.0001, p = 0.009) and AMBN (p = 0.002, p = 0.001, p = 0.0001) staining of all groups were significantly lower than that of the control group in the secretory, transitional, and maturation stages. Abnormal enamel matrix formation was observed in the H&E and GT staining sections of all experimental groups. Yellowish coloration of the amoxicillin group was observed in morphologic evaluation.

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.

Molar-incisor hypomineralization and the association with childhood illnesses and antibiotics in a group of Finnish children

OBJECTIVE

Molar-incisor hypomineralization (MIH) is a developmental enamel defect affecting 1-4 first permanent molars (FPMs) and often also incisors. The aim of this study was to assess whether childhood illnesses or medication are associated with MIH.

MATERIAL AND METHODS

FPMs and incisors of 287 Finnish children were examined for MIH in line with the criteria of the EAPD. Health data from the first 3 years of life was collected from medical records and the associations with MIH and MIH2 (lesions in at least one FPM and incisor) were assessed using simple and multiple logistic regression analyses.

RESULTS

The prevalence of MIH and MIH2 were 11.5% and 6.3%, respectively. During the first 3 years of life, the children with MIH had sought care for infectious illnesses more often than the children without MIH (mean number of visits (SD) 7.9(6.4) vs. 6.0(5.1), p = 0.045, independent samples t-test). After adjustment for confounding factors, children who had received penicillin or macrolides within the first year, or amoxicillin within the first 3 years had a higher risk for MIH (2.61, 4.07 and 2.58 times, adjusted OR, respectively) or MIH2 (3.16 times, aOR for penicillin and amoxicillin) compared to those who had not received that antibiotic. Of the illnesses, children with at least one episode of otitis within the first year had a higher risk for MIH (2.28 times, aOR) than those who had not suffered from otitis.

CONCLUSIONS

Acute otitis media and the use of certain antibiotics were associated with the elevated risk of MIH/MIH2.

Amoxicillin diminishes the thickness of the enamel matrix that is deposited during the secretory stage in rats

BACKGROUND

The use of amoxicillin during early childhood has been associated with molar incisor hypomineralization.

AIM

The objective of this study was to determine whether the use of amoxicillin interferes with enamel development, during secretion and early mineralization stages.

DESIGN

Fifteen pregnant rats were randomly assigned to three groups that received physiological solution (sham group), 100 mg/kg/day amoxicillin (A100G), and 500 mg/kg/day amoxicillin (A500G). After birth, the pups in each group received the same treatment until post-natal day 7 or 12. The upper first molars were analyzed histomorphometrical and immunostaining with amelogenin on day 7, and MMP-20 on day 12 was performed using a semiquantitative method (H-score).

RESULTS

At 7 days, several vacuolar structures were observed in the ameloblasts in the A100G and A500G groups. A significant reduction of the enamel thickness (P < 0.001) was found in amoxicillin-treated rats compared with the sham group. Significant differences were not observed in enamel thickness (P > 0.05) between the groups of 12-day-old rats. Moreover, significant differences were not observed in the number of amelogenin- and MMP-20-immunolabeled ameloblasts (P > 0.05) between groups.

CONCLUSION

The present results suggest that amoxicillin interferes with the initial stages of amelogenesis by causing structural changes in the ameloblasts and a reduction of the enamel matrix.

Aetiology of Molar-Incisor Hypomineralisation: A systematic review

AIM

This was to review and assess the studies on aetiology of Molar-Incisor Hypomineralisation (MIH) or, as a proxy, of demarcated opacities in permanent first molars and to consider the potential factors involved with findings obtained in animal experiments.

METHODS

A systematic search by Medline online database was performed. Abstracts behind appropriate titles were studied and finally the full articles were evaluated for their strength of evidence in the aetiology of MIH.

RESULTS

From a total of 1,142 articles 28 were identified and selected for review. The selected papers covered medical problems in prenatal, perinatal and postnatal period, medication of the child during the first years of life, and exposure to fluoride or environmental toxicants (dioxins and PCBs) in the early childhood. Based on the assessment of the articles it was still not possible to specifically name those factors causing MIH although correlations between several potential factors and MIH were presented. Among the factors suggested and found to cause enamel defects in animal experiments were: high fever, hypoxia, hypocalcaemia, exposure to antibiotics (amoxicillin, a macrolide), and dioxins.

CONCLUSION

Despite increased knowledge on the aetiology of MIH insufficient evidence to verify the causative factors exists. Further studies, especially prospective ones, are needed to improve the level and strength of evidence of the role of the present putative factors and to reveal new factors that may be involved. Any combined effect of several factors should be taken into account. Experimental dose/response studies and research on the molecular mechanisms causing the abnormal function of the ameloblasts are also necessary to deepen our knowledge of MIH.