Predentin changes in patients with chronic renal failure

Low Dentin Matrix Protein 1 Is Associated With Incident Cardiovascular Events in Peritoneal Dialysis Patients

Recent reports demonstrated that dentin matrix protein 1 (DMP1) acts as an inhibitor of vascular calcification and might be a potential biomarker for chronic kidney disease-mineral and bone disorder; however, no clinical investigations regarding DMP1 have been performed in dialysis patients. We investigated the prognostic value of DMP1 on cardiovascular outcomes in prevalent peritoneal dialysis patients. We recruited 223 prevalent peritoneal dialysis patients and divided them into high and low DMP1 groups according to log-transformed plasma DMP1 levels. Lateral lumbar spine radiographs were used for measurement of vascular calcification. Major cardiovascular events were compared between the two groups. A Cox proportional hazards analysis determined DMP1 was independently associated with cardiovascular outcomes. In vitro mouse osteocytes were cultured in media containing indoxyl sulfate (IS), and the expressions of DMP1 were examined. The mean age was 52.1 ± 11.8 years, and 116 (52.0%) patients were male. The median value of log DMP1 was 0.91 (0.32-2.81 ng/mL). The multiple logistic regression analysis indicated that DMP1 levels were independently associated with the presence of vascular calcification after adjustment for multiple confounding factors (odds ratio = 0.719; 95% confidence interval [CI] 0.522-0.989; p = 0.043). During a mean follow-up duration of 34.6 months, incident cardiovascular events were observed in 41 (18.4%) patients. A Kaplan-Meier plot showed that the low DMP1 group had a significantly higher rate of incident cardiovascular events compared with the high DMP1 group (log-rank test, p = 0.026). In addition, multiple Cox analysis showed that low DMP1 was significantly associated with incident cardiovascular events (log 1 increase: hazard ratio = 0.855; 95% CI 0.743-0.984; p = 0.029) after adjustment for multiple confounding factors. In IS-stimulated osteocytes, mRNA and protein expression levels of DMP1 were significantly decreased compared with control osteocytes. We showed that low DMP1 levels were significantly associated with presence of vascular calcification and were independently associated with the incident cardiovascular events in prevalent peritoneal dialysis patients. DMP1 might be a potential factor contributing to cardiovascular complications in dialysis patients. © 2016 American Society for Bone and Mineral Research.

Predentin thickness analysis in developing and developed permanent teeth

BACKGROUND

Predentin, the unmineralized organic matrix is important in maintaining the integrity of dentin. It is usually thick where active dentinogenesis occurs. A wide variation in its thickness is reported. Hence, we determined the variation in predentin thickness at various sites of different age groups.

MATERIALS AND METHODS

60 freshly extracted teeth (maxillary and mandibular first premolars) were divided into three groups with 20 teeth in each as, Group 1 - teeth with incomplete root formation (age <16 years), Group 2 - teeth with complete root formation (aged between 16 and 30 years), Group 3 - teeth of patients aged above 30 years. The teeth were fixed, decalcified and sections of 6 μ thickness were obtained, and stained with hematoxylin and eosin. The distance between the odontoblastic cell layers of the pulp to the border line of the dentin was considered for the measurement of the predentin thickness. A total of nine sites were considered for each specimen.

RESULTS

The present study revealed varied mean predentin thickness at all nine sites in all three age groups. Maximum and minimum thickness was observed at the apex and pulp floor respectively in all three groups. There was a statistical significant difference in predentin thickness between groups 1 and 3 and 2 and 3.

CONCLUSION

The predentin thickness in the first group gradually increased toward the growing end near the apex, while it was relatively constant in the second group and increased overall thickness at all the sites in the third group. A notable finding was a linear increase with age in width of the predentin and the thickness vary as a function of odontoblastic activity during different stages of tooth development.

Fourier transform Infrared spectroscopic characterization of mineralizing type I collagen enzymatic trivalent cross-links

The most abundant protein of bone's organic matrix is collagen. One of its most important properties is its cross-linking pattern, which is responsible for the fibrillar matrices' mechanical properties such as tensile strength and viscoelasticity. We have previously described a spectroscopic method based on the resolution of the Amide I and II Fourier transform Infrared (FTIR) bands to their underlying constituent peaks, which allows the determination of divalent and pyridinoline (PYD) collagen cross-links in mineralized thin bone tissue sections with a spatial resolution of ~6.3 μm. In the present study, we used FTIR analysis of a series of biochemically characterized collagen peptides, as well as skin, dentin, and predentin, to examine the potential reasons underlying discrepancies between two different analytical methodologies specifically related to spectral processing. The results identified a novel distinct FTIR underlying peak at ~1,680 cm(-1), correlated with deoxypyridinoline (DPD) content. Furthermore, the two different methods of spectral resolution result in widely different results, while only the method employing well-established spectroscopic routines for spectral resolution provided biologically relevant results, confirming our earlier studies relating the area of the underlying 1,660 cm(-1) with PYD content. The results of the present study describe a new peak that may be used to determine DPD content, confirm our earlier report relating spectroscopic parameters to PYD content, and highlight the importance of the selected spectral resolution methodology.

Retentiveness of metal coping luted to teeth of uremic patients undergoing hemodialysis using five different luting cements

OBJECTIVES

This study aimed to assess the retention of metal copings luted to uremic teeth with five different luting agents.

METHODS

A total of 35 sound natural molars was collected from uremic patients and randomly assigned into five groups (n=7). The teeth were prepared for metal copings using diamond tips and water coolant. Metal copings with a loop on the occlusal surface were fabricated using base metal alloy (Rexillium III). The copings were luted using Fuji I, glass ionomer (GI); Fuji Plus, resin-modified glass ionomer (RMGI); Panavia F 2.0, resin cement; Rely X Unicem, self-adhesive cement (SA); and Adhesor, zinc phosphate cement (ZPh). All specimens were incubated at 37°C for 24 hours, conditioned in artificial saliva for 7 days, and then thermocycled for 5000 cycles (5°C-55°C). The dislodging force was measured using a universal testing machine at a crosshead speed of 2 mm/min. The mode of failure of the loaded adhesive copings was evaluated. Statistical analyses were performed using one-way analysis of variance and Tukey post hoc test.

RESULTS

GI and SA cements had the highest and the lowest mean retentive strength, respectively (580.90±17.3, 406.6±12.7). There was no significant difference between ZPh, SA, and resin cements. These cements were inferior to GI and RMGI cements (p<0.05), which showed statistically similar retentive strengths.

CONCLUSIONS

The results of this study support the use of glass ionomer and resin-modified glass ionomer cements for luting of metal copings to uremic teeth with retentive preparations.

Effect of 16% carbamide peroxide bleaching gel on enamel and dentin surface micromorphology and roughness of uremic patients: an atomic force microscopic study

Objectives:

To investigate the effect of 16% carbamide peroxide bleaching gel on surface micromorphology and roughness of enamel and root dentin of uremic patients receiving hemodialysis using atomic force microscopy (AFM).

Methods:

A total of 20 sound molars were collected from healthy individuals (n=10) and uremic patients (n=10). The roots were separated from their crowns at the cemento-enamel junction. Dental slabs (3 mm x 2 mm x 2 mm) were obtained from the buccal surface for enamel slabs and the cervical third of the root surface for dentin slabs. Dental slabs were then flattened and serially polished up to #2500-grit roughness using silicon carbide abrasive papers. Half of the slabs obtained from healthy individuals and uremic patients were stored in artificial saliva and left without bleaching for control and comparison. The remaining half was subjected to a bleaching treatment using 16% carbamide peroxide gel (Polanight, SDI Limited) 8 h/day for 14 days and stored in artificial saliva until AFM analysis was performed. Statistical analysis of the roughness average (Ra) results was performed using one-way ANOVA and Bonferroni post hoc multiple comparisons test.

Results:

The micromorphological observation of bleached, healthy enamel showed exaggerated prism irregularities more than non-bleached specimens, and this observation was less pronounced in bleached uremic enamel specimens with the lowest Ra. Bleached healthy dentin specimens showed protruded peritubular dentin and eroded intertubular dentin with the highest Ra compared to bleached uremic dentin.

Conclusions:

The negative effects of the bleaching gel on uremic tooth substrates are less dramatic and non-destructive compared to healthy substrates because uremia confers different micromorphological surface changes.

The effect of fluoride on enamel and dentin formation in the uremic rat incisor

Renal impairment in children is associated with tooth defects that include enamel pitting and hypoplasia. However, the specific effects of uremia on tooth formation are not known. In this study, we used rat mandibular incisors, which continuously erupt and contain all stages of tooth formation, to characterize the effects of uremia on tooth formation. We also tested the hypothesis that uremia aggravates the fluoride (F)-induced changes in developing teeth. Rats were subjected to a two-stage 5/6 nephrectomy or sham operation and then exposed to 0 (control) or 50 ppm NaF in drinking water for 14 days. The effects of these treatments on food intake, body growth rate, and biochemical serum parameters for renal function and calcium metabolism were monitored. Nephrectomy reduced food intake and weight gain. Intake of F by nephrectomized rats increased plasma F levels twofold and further decreased food intake and body weight gain. Uremia affected formation of dentin and enamel and was more extensive than the effect of F alone. Uremia also significantly increased predentin width and induced deposition of large amounts of osteodentin-like matrix-containing cells in the pulp chamber. In enamel formation, the cells most sensitive to uremia were the transitional-stage ameloblasts. These data demonstrate that intake of F by rats with reduced renal function impairs F clearance from the plasma and aggravates the already negative effects of uremia on incisor tooth development.

Pathologie buccodentaire et sa prise en charge chez les insuffisants rénaux chroniques

Bad dental status is very often observed in hemodialyzed patients due to the fact of a frequent poor oral hygiene and, in addition of the traditional risk factors, the consequences of uraemic state and its treatment. However , among such immunodepressed patients, oral and dental lesions represent a risk of septic complications. Moreover some works point out the prevalence of inflammation and denutrition due to dental lesions in the uraemic population, with potential atherosclerosis. Therefore, in order to anticipate all these adverse effects and to restore their mouth to health, patients have to be encouraged to have regularly a full dental evaluation and correction if not elimination of all potential sources of infection and other complications. To ensure the best treatment, a close collaboration has to be established with dental practitioners who must be aware and convinced of the complexity of such patients: immunodepression due to uraemic state and sometimes to drug therapy; importance of prophylactic antibiotic therapy surrounding dental cares; cautions to hemostasis circumstances; adjusted use of some medications. To illustrate this matter, we report here a study involving 96 hemodialyzed patients who were investigated by panoramic radiography and clinical cross- examination about their dental complaints and habits. We then expose our practices and detail our collaboration with their dentists in establishing a plan of dental treatment.

Oral and dental aspects of chronic renal failure

The present article reviews, in detail, the current knowledge of the oral and dental aspects of chronic renal failure (CRF). Worldwide, increasing numbers of persons have CRF; thus, oral health care staffs are increasingly likely to provide care for patients with such disease. Chronic renal failure can give rise to a wide spectrum of oral manifestations, affecting the hard or soft tissues of the mouth. The majority of affected individuals have disease that does not complicate oral health care; nevertheless, the dental management of such individuals does require that the clinician understand the multiple systems that can be affected. The clinician should also consider the adverse side-effects of drug therapy and appropriate prescribing, in view of compromised renal clearance.

Effect on human teeth of renal transplantation: a postmortem study

Extracted teeth from five deceased patients treated by renal transplantation were examined radiographically and histologically, and compared with teeth from healthy persons of approximately the same age. In three of the patients with a renal transplant, the radiographs showed normal pulp chamber sizes, but histologic examination revealed a widened predentin zone, approximately four times greater than in the controls. In two of the patients the radiographs showed marked reduction of the pulp chamber size. The histologic changes of these teeth were mainly an extensive amount of secondary dentin along the pulp chamber walls and the root canals, with a markedly reduced pulp space. One explanation for the difference between the patients was that patients with extensive pulp calcifications were given a higher total amount of corticosteroids than patients with a widened predentin zone.

Pulp narrowing in renal end stage and transplanted patients

A comparison of relative dental pulp size in chronic renal disease patients with dental pulp size in healthy controls revealed a significant pulp narrowing in the kidney disease group (n = 44). A strong correlation between the chronicity of the renal disease and the pulp narrowing was found in the premolar and molar teeth of the tested group. A review of the literature concerning pulp narrowing is also presented.

Dentin in chronic renal failure: an ultrastructural study

Disturbances in the mineralization of hard tissues in patients suffering from chronic renal failure and in patients undergoing chronic hemodialysis are a well-established phenomenon. These disturbances are the result of complex pathophysiologic alterations in calcium and phosphorus metabolism. Disturbances in the dentin of teeth, analagous to those occurring in bone, were not recognized until 1983 when it was reported that a significantly thicker predentin layer was present in the teeth of patients with chronic renal failure and in patients being treated with chronic hemodialysis (1). The aim of the present study was to conduct a comparative ultrastructural (SEM) analysis of dentin in this group of patients. A wide spectrum of changes was detected, ranging from mild disturbances with increasing tubule irregularity and focal obliteration of tubule lumens, to widespread formation of dysplastic dentin exhibiting numerous mineralized, largely atubular globules with only occasional large, irregular tubules. In general, these changes appeared to reflect the type and effectiveness of treatment rendered (renal transplant or hemodialysis therapy). The findings suggest that dentin exhibits significant ultrastructural alterations when the underlying homeostatic regulation of calcium and phosphorus metabolism is disturbed in systemic disorders such as chronic renal failure.

Oral manifestations of oxalosis secondary to ileojejunal intestinal bypass

Oxalosis is a rare condition that may be either hereditary or acquired. It may be secondary to a number of primary causes, which include renal failure, oxalate poisoning, malabsorption syndromes, and in this case, ileojejunal bypass surgery. Systemic oxalate overload following such bypass surgery results from a defect in the enterohepatic circulation and from the loss of calcium and bile salts in the feces. The oxalate is then absorbed into the circulation, and the supersaturated solution precipitates in the systemic tissues. Reported cases of oral involvement are rare. This article presents a 2 1/2-year follow-up of such a patient and the resultant progressive and unrelenting nature of the disorder. As a result of our experience, we suggest early aggressive oral surgical management of the widespread oral lesions.

Dental management of chronic haemodialysis patients

In 44 patients (22 females, 22 males, aged 18-61 years, mean 36 years) regular dental screening and treatment were started in January 1982. Two years follow-up revealed that the oral hygiene of these haemodialysis patients was worse than that of the average population. In 42 cases calculus formation and gingivitis, in each case atrophy of the alveolar bone and pocket formation were found. We consider these symptoms as cardinal in uraemic haemodialysis patients. As a consequence, the teeth had a pathologic mobility which was proportional to the bone resorption. Although not very typical, 10 cases were found with clicking of the temporomandibular joint associated with painfulness of the joint and the surroundings. Owing to the increased tendency to caries and the parodontal disease, the majority of patients lost most of their teeth untimely. Therefore special measures should be taken to achieve restoration. We emphasize the need for special dental care of haemodialysis patients.

The effect of aging on tooth morphology: a study on impacted teeth

The effect of age on dental tissues was studied on histologic sections of totally impacted teeth obtained from patients between 11 and 76 years of age. Impacted teeth were used in order to obviate the influence of the environmental effects prevalent in the oral cavity. The presence of concentric denticles and diffuse calcifications was determined, and the width of secondary dentin, predentin, and cementum was measured. The width of predentin and cementum increased linearly with age, whereas the aging process of secondary dentin formation and diffuse calcifications followed a different pattern. The incidence of concentric denticles was identical for all age groups.