The effects of cyclophosphamide on eruption of the continuously growing mandibular incisor of the rat

Dental developmental complications in pediatric hematopoietic stem cell transplantation patients: A study using CMC clinical data warehouse

OBJECTIVE

This study aimed to investigate the prevalence and extent of dental developmental complications in patients who have undergone pediatric hematopoietic stem cell transplantation (SCT) and identify the risk factors.

MATERIALS AND METHODS

We retrospectively investigated the clinical data warehouse of the Catholic Medical Center information system for identifying patients who: 1) visited the Department of Pediatrics between 2009 and 2019, 2) underwent SCT under the age of 10, and 3) had panoramic radiographs. Thus 153 patients were included in this study. The prevalence and extent of tooth agenesis, microdontia, and root malformation were assessed using panoramic radiographs obtained after SCT, and the risk factors were analyzed using regression analysis.

RESULTS

All 153 patients had at least one dental anomaly. When grouped according to the age at initial chemotherapy (≤ 2.5; 2.6-5.0; 5.1-7.5; > 7.5 years), the prevalence of agenesis showed statistically significant differences among the different age groups (P < 0.001). The prevalence of agenesis was highest in the youngest age group. As the initial age at chemotherapy increased, the number of affected teeth per patient decreased for all three anomalies. The location of the affected tooth was also influenced by the age at initial chemotherapy. Regression analysis demonstrated that young age at initial chemotherapy was a risk-increasing factor for tooth agenesis and microdontia.

CONCLUSIONS

The age at initial chemotherapy may be a critical factor in determining the type, extent, and location of dental complications after SCT. These results suggest that careful dental follow-up and timely treatment are recommended for pediatric patients undergoing SCT.

The effects of aging on the eruptive behavior of the mandibular incisor in male rats

Several studies have highlighted the lack of age changes in the extracellular matrix of the periodontal ligament, but more needs to be known about cellular and functional changes (including the effects upon eruption). For this study, impeded and unimpeded eruption rates were measured over a 2-week period for the mandibular incisors of a group of 24-month-old rats. The technique used for measuring eruption was similar to that described by Bryer [15]. Both impeded and unimpeded eruption rates were found to be significantly increased (p < .01) compared with those obtained from a group of rats aged 8 weeks. These changes might be related to changes in the mechanism(s) responsible for the generation of the eruptive force(s) or to changes in the resistance of the tissues to such forces.

A comparison between a conventional optical method and image-analysis for measuring the unimpeded eruption rate of the rat mandibular incisor

The impeded/unimpeded eruption rates of the rat incisor have been much studied. The most commonly used optical microscopic method, which has inherent weaknesses, was compared here with an image-analysis method to measure the eruption rate of the mandibular incisor. The study also evaluated the incisal edge as a reference point for the measurement of the unimpeded eruption rate, and the frequency of shortening the mandibular incisor. The image-analysis method was found to be a simple and reliable technique that could replace the optical method. There was no significant difference between the data from the two methods; their kappa coefficients were similar at the 0.99 level. It was concluded that shortening the incisor in the measurement of the unimpeded eruption rate should be done at least every 48 h, and that the incisal edge of the shortened incisor can be used as the reference point for that measurement.

The effect of lead on the eruption rates of incisor teeth in rats

The effects of lead on the continuously erupting rat incisors under normo-, hyper- and hypofunctional conditions were investigated. Left lower incisors of 20 rats were rendered unimpeded (hypofunctional) by cutting them out of occlusion every 2 days; the right lower incisors of these rats were considered hyperfunctional. Measurements on normally growing teeth (normofunctional) were carried out in a group of ten rats whose teeth were not cut but only marked every 2 days. On day 7 of the experiment, half of the rats from these two groups were given a single intraperitoneal injection of lead acetate (40 mg/kg), and the other half received sodium acetate (22 mg/kg). Another group of 15 rats was used to obtain blood samples for lead determination 1 h, and 10, 20, and 30 days after lead administration. Animals were killed on day 32. Hypofunctional incisors from lead-treated rats erupted more slowly than control ones (P<0.05). These results show a previously unreported toxic effect of heavy metals.

A scanning electron microscopy study of disturbances in the developing rat molar induced by cyclophosphamide

Scanning electron microscopy was used to study the effect of cyclophosphamide (Cy) on molar development in 18 Sprague-Dawley rats from 15 to 48 days of age after birth. Doses of 30 mg/kg body weight of Cy dissolved in 1 ml 0.9% NaCl were given to the rats at 10 and 13 days of age. Eighteen control rats had injections of 1 ml 0.9% NaCl at the same ages. The most obvious changes in the experimental teeth were found in the developing roots of the first and second molars and in both the crown and roots of the third molar. The roots of the first and second molars were short and showed apical closure in the experimental rats. In addition to the disturbances in crown and root formation, the third molars were also significantly reduced in total size as compared with the third molars in the control rats.

Influence of the antineoplastic agent cyclophosphamide on dental development in rat molars

The effect of cyclophosphamide (Cy) on tooth development was studied in molars of 18 young Sprague-Dawley rats. Doses of 30 mg/kg body weight of Cy dissolved in 1 ml 0.9% NaCl were administered to 18 experimental rats and 1 ml 0.9% NaCl to 18 control rats at 10 and 13 days of age. The most obvious changes in the experimental teeth could be seen in the developing pulp of the third molar and developing roots of the first and second molars. Wide cell-free areas appeared in the third molar 2 days after the last injection; later these areas turned into mineralized osteodentin. Similar areas could be observed also in the roots of the first and second molars. These changes were related to the developmental stage of the area.

The effect of cyclophosphamide on the eruption of impeded and resected incisors in rats

It is known that a single dose of cyclophosphamide (40 mg.kg-1 intraperitoneal) slows the eruption of unimpeded incisors but has no effect on impeded incisors. In this study incisors that were impeded when cyclophosphamide was given were subsequently made unimpeded. When they were unimpeded they erupted more slowly than the controls. Therefore the changes cyclophosphamide produces which slow eruption are formed in impeded incisors but have an effect only in unimpeded incisors. It has been reported that cyclophosphamide slows the eruption of resected incisors when it is given before the resection. In a second experiment cyclophosphamide was given after the resection and had no effect on eruption rates. It is suggested from these and earlier findings that cyclophosphamide slows eruption by imposing a maximum on the rate at which it can occur and that it does so through the changes it produces in the periodontal ligament. The periodontal changes make it harder for the tooth to move rather than altering the forces moving the tooth. This explanation of how cyclophosphamide slow eruption produces an alternative interpretation of some, but not all, of the findings that have been cited as evidence that there are two mechanisms of tooth eruption.

The effect of corticosteroids and cyclophosphamide on the eruption of resected incisor teeth in the rat

It has been observed that there may be two mechanisms making resected rat incisors erupt during their phase of normal eruption rates, only one of which works during their slow phase of eruption. The effects of cyclophosphamide and corticosteroids on the eruption of non-resected teeth may also be consistent with the presence of two eruptive mechanisms, one responsive to cyclophosphamide and corticosteroids, the other not, or less, responsive to them. To see whether this previous work has, in different experiments, revealed the same pair of mechanisms, the effects of cyclophosphamide and corticosteroids on resected incisors were investigated. Cortisone accelerated their eruption and cyclophosphamide slowed it when they were erupting at normal rates, but neither compound had any effect during the initial slow phase.

Altered dental root development in long-term survivors of pediatric acute lymphoblastic leukemia. A review of 17 cases

Seventeen patients treated for acute lymphoblastic leukemia by combination chemotherapy before their reaching 10 years of age were studied for altered dental root development of their premolar teeth. Five of the 17 patients showed subjective radiographic evidence of marked shortening of the premolar dental roots; 13 had thinning of the roots. A quantitative analysis was developed and verified, which disclosed a 63.33% to 84.38% reduction of premolar root length when compared with the mean of the historical controls. With recent significant increases in long-term survival rates of children with malignancies, altered dental development becomes an important factor to follow years after chemotherapy is discontinued. The findings of these chemotherapy-associated dental development changes impacts on the patient's quality of life and also can serve as a research tool to assess permanent effects of chemotherapy on normal tissue growth and development.

Effects of colchicine and hydrocortisone on unimpeded eruption rates of root-resected mandibular incisors of rats

A single injection of colchicine and daily injections of hydrocortisone have opposite effects on tooth eruption, respectively causing marked reduction and marked increase in unimpeded eruption rates in the root-resected incisors of rats. Unimpeded eruption rates of both root-resected and normal, non-resected, incisors responded identically to these two drugs, providing support for the view that the eruptive process following root resection is physiological. It was not possible to obtain direct evidence relating to either the hydrostatic pressure or the periodontal fibroblast hypotheses of tooth eruption; the drugs used to affect the eruption rates of resected rat incisors could also affect either the tissue hydrostatic pressure or the motility or contractibility of periodontal fibroblasts or both.

Interactions between thyroxine, hydrocortisone and cyclophosphamide in their effects on the eruption of the rat mandibular incisor

The effects on the unimpeded eruption rates of the rat mandibular incisor of daily doses of thyroxine (0.5 mg/kg) and hydrocortisone (12.5 mg/kg) and of a single injection of cyclophosphamide (40 mg/kg), either alone or in combination, were studied over approximately 15 days. Both the thyroxine and hydrocortisone alone produced increases in eruption, whereas a decrease was recorded with cyclophosphamide alone. When thyroxine was combined with hydrocortisone, the increase in eruption rate was greater than that with thyroxine or hydrocortisone alone. When cyclophosphamide was combined with hydrocortisone, there was no difference compared with cyclophosphamide alone. These results obtained with drug combinations are consistent with eruption having a multifactorial basis.