Effects of phosphoric acid concentration and etching duration on enamel and dentin tissues of uremic patients receiving hemodialysis: an AFM study.

PURPOSE: Using atomic force microscopy (AFM), the purpose was to investigate the effect of phosphoric acid (H3PO4) concentration and etching duration on surface roughness (Ra) and micromorphology of enamel and dentin substrates of uremic patients receiving hemodialysis. MATERIALS AND METHODS: Sixty-three enamel and dentin slabs were prepared from 42 sound natural molars collected from uremic patients under hemodialysis and mechanically polished up to 4000-grit roughness. Nine slabs of each substrate were not etched (control group). The remaining slabs were divided into two experimental groups (n = 27) according to etchant concentration (37% or 42%). In each group, 9 specimens were etched for 15, 30, and 60 s. The surface morphology of the control and test specimens was examined by AFM operated in "contact" mode. The obtained Ra was subjected to statistical analysis. RESULTS: Statistical analysis showed that increasing the duration of acid application (irrespective of acid concentration and type of substrate) significantly increased the amount of Ra. H3PO4 at a concentration of 42% was more effective at producing Ra than was H3PO4 at 37% for all 3 application times. The Ra quantity produced by H3PO4 at 42% was time specific, with 15 s being significantly less effective than 30 or 60 s. However, 60 s was significantly better than 30. CONCLUSION: The findings of this study support the use of 42% H3PO4 for etching uremic hard tooth tissues for 60 s.

Decalcification prevention around orthodontic brackets bonded to bleached enamel using different topical agents.

BACKGROUND: The present study was conducted to evaluate the effect of different topical agents utilized for prevention of enamel decalcification around orthodontic brackets bonded to bleached and non-bleached enamel. METHODS: Human maxillary premolars (n = 120) were divided into two equal groups. Teeth in group I were left without bleaching while those in group II were bleached with Vivastyle gel. Metal brackets were bonded to all the teeth using light-cured adhesive. Each group was divided into six equal subgroups (A, B, C, D, E, and F). In subgroup A, no material was applied (control). In subgroups B, C, D, E, and F, the following materials were applied respectively: Profluorid varnish, Enamel Pro Varnish, Ortho-Choice Ortho-Coat, GC Tooth Mousse, and GC MI Paste Plus. All teeth were cycled in a demineralization solution/artificial saliva for 15 days. Laser fluorescence was used to measure the level of enamel mineralization. The data were statistically analyzed. RESULTS: Regarding the non-bleaching subgroups, all studied material revealed significant demineralization reduction in comparison to the control subgroup (P < 0.05). Ortho-Choice Ortho-Coat revealed the highest significant effect while GC Tooth Mousse showed the least effect. In bleached subgroups, Profluorid varnish, Enamel Pro Varnish, and Ortho-Choice Ortho-Coat significantly reduced demineralization (P < 0.05) while either GC MI Paste Plus or GC Tooth Mousse had no significant effects (P > 0.05). CONCLUSIONS: Ortho-Choice Ortho-Coat, and Profluorid and Enamel Pro varnishes could be utilized successfully to reduce enamel demineralization around brackets bonded to either bleached or non-bleached enamel. GC MI Paste Plus and GC Tooth Mousse were effective only in non-bleached enamel.

Impact of three different mouthwashes on the incidence of gingival overgrowth induced by cyclosporine-A: a randomized controlled experimental animal study.

OBJECTIVE: This study aimed to evaluate the effects of three different mouthwashes on the incidence of cyclosporine-A-induced gingival overgrowth. STUDY DESIGN: One hundred albino rats were divided into five equal groups. Group I rats received no treatment. Group II rats were administered cyclosporine-A. Group III, IV, and V rats were handled as group II and concomitantly treated with chlorhexidine gluconate, cetylpyridinium chloride, and essential oil mouthwashes, respectively. Ten rats from each group were euthanized after the first week of treatment, and the remaining rats were euthanized after the second week of treatment. The obtained specimens were stained with hematoxylin and eosin, Masson's trichrome, and tumor growth factor beta (TGF-ß), matrix metalloproteinase 1 (MMP-1), and interleukin 6 (IL-6) immunohistochemical stains. RESULTS: The histologic findings at the end of the first and second weeks revealed marked increases in gingival overgrowth for groups II and IV in comparison with groups III and V. Increased epithelial thickness and collagen accumulation were prominent in groups II and IV compared with the other groups. Groups II and IV revealed the highest immunoreactivities for TGF-ß and for IL-6. Groups I, III, and V revealed the highest level of MMP-1 expression. CONCLUSIONS: Essential oils and chlorhexidine gluconate mouthwashes significantly reduced the incidence of gingival overgrowth compared with cetylpyridinium chloride.

The effects of surgicel and bone wax hemostatic agents on bone healing: An experimental study.

BACKGROUND: The biological effects of hemostatic agends on the physiological healing process need to be tested. The aim of this study was to assess the effects of oxidized cellulose (surgicel) and bone wax on bone healing in goats' feet. MATERIALS AND METHODS: Three congruent circular bone defects were created on the lateral aspects of the right and left metacarpal bones of ten goats. One defect was left unfilled and acted as a control; the remaining two defects were filled with bone wax and surgicel respectively. The 10 animals were divided into two groups of 5 animals each, to be sacrificed at the 3(rd) and 5(th) week postoperatively. Histological analysis assessing quality of bone formed and micro-computed tomography (MCT) measuring the quantities of bone volume (BV) and bone density (BD) were performed. The results of MCT analysis pertaining to BV and BD were statistically analyzed using two-way analysis of variance (ANOVA) and posthoc least significant difference tests. RESULTS: Histological analysis at 3 weeks showed granulation tissue with new bone formation in the control defects, active bone formation only at the borders for surgicel filled defects and fibrous encapsulation with foreign body reaction in the bone wax filled defects. At 5 weeks, the control and surgicel filled defects showed greater bone formation; however the control defects had the greatest amount of new bone. Bone wax filled defects showed very little bone formation. The two-way ANOVA for MCT results showed significant differences for BV and BD between the different hemostatic agents during the two examination periods. CONCLUSION: Surgicel has superiority over bone wax in terms of osseous healing. Bone wax significantly hinders osteogenesis and induces inflammation.

Altered coronal tissue of the human dental pulp in chronic hepatitis C virus infected patients.

INTRODUCTION: Hepatitis C virus (HCV) infection is characterized by a high rate of chronicity and concerns 170 million individuals worldwide. Extrahepatic manifestations are frequently observed in patients with chronic viral hepatitis. Although extrahepatic manifestations do exist with all hepatitis viruses, they are more commonly associated with chronic HCV infection. This study aimed to evaluate qualitatively and quantitatively the effect of chronic HCV infection on the coronal tissue of the human dental pulp. METHODS: Thirty sound impacted teeth were obtained from healthy individuals as healthy controls. The patient group included another 30 sound impacted teeth obtained from chronic HCV-infected patients. The coronal pulp tissues were carefully removed, fixed, and processed to be stained with hematoxylin-eosin, alcian blue (2.5)/periodic acid-Schiff, van Gieson, and fibronectin. RESULTS: The tissue sections of chronic HCV patients revealed disorganized pulp tissue, chronic inflammatory cell infiltrate, thickening, stenosis and occlusion of large-sized blood vessel arteriole, and collapsed venule and lymphatic system. The acidic, neutral, and mixed mucins were increased, whereas the amount of collagen was decreased, accompanied with marked decrease in the distribution and quantity of fibronectin glycoprotein. Application of Kruskal-Wallis test showed that there were statistically significant changes between the 2 groups (P ≤ .05). CONCLUSIONS: The coronal tissue of the dental pulp, like any other body tissues, is affected by chronic HCV infection, with an inappropriate cellularity, vasculature, and extracellular matrix proteins. The clinician should be alerted to these histologic changes and their subsequent implications.

Intracoronal mandibular Kennedy Class I implant-tooth supported removable partial overdenture: a 2-year multicenter prospective study.

PURPOSE: The aim of this study was to assess the clinical status and radiographic and densitometric peri-implant tissue changes as parameters for the success or failure of 40 mandibular implants supporting intracoronal mandibular Kennedy Class I removable partial overdentures in a 2-year prospective study. MATERIALS AND METHODS: Twenty consecutively treated men who received mandibular implants bilaterally to support an intracoronal Kennedy Class I removable partial overdenture were selected. Plaque and gingival bleeding indices, probing pocket depths, marginal bone loss, and bone mineral density were recorded. Bone loss and density were assessed through intraoral periapical radiographs and dual-energy x-ray absorptiometry, respectively. Data were recorded at the time of overdenture insertion and 6, 12, 18, and 24 months later. RESULTS: Two implants failed, resulting in a success rate of 95% after 24 months. The plaque and gingival bleeding indices changed significantly between the different observational periods. Within the physiologic limit, there were detrimental effects on both marginal bone levels and probing pocket depths. Meanwhile, the bone mineral density around the implants increased significantly in a time-dependent manner. CONCLUSION: Within the limitations of this study, mandibular implants supporting an intracoronal Kennedy Class I removable partial overdenture can be recommended as a viable treatment modality for rehabilitation of patients with partial bilateral mandibular posterior edentulism.

Vasculitis of dental pulp associated with cryoglobulinemia in hepatitis C virus patients: case report.

INTRODUCTION: This report presents a case of impacted lower third molar extracted for surgical reasons in patient with uncontrolled hepatitis C. After decalcification, dental pulp vasculature and its tissue quality were investigated. METHODS: Serial sections of 4-µm thickness along the midline buccolingually for the demineralized specimen were obtained, mounted on a glass slide, stained with hematoxylin-eosin, covered, and viewed under the light microscope. RESULTS: The histologic investigation of the pulp tissue revealed thickening, stenosis, and occlusion of the vessel wall, ectopic calcification of the pulp tissue in close association with pulpal blood vessels, interrupted and vacuolated odontoblastic layer in the coronal pulp chamber, with an inflammatory cell infiltrate throughout the pulpal tissue. CONCLUSIONS: Cryoglobulinemia associated with uncontrolled hepatitis C virus infection in patients endangers the dental pulp vasculature and alters its normal tissue architecture.

Influence of selective immunosuppressive drugs on the healing of exposed dogs' dental pulp capped with mineral trioxide aggregate.

INTRODUCTION: Immunosuppressive drugs are used in clinical medicine for a variety of disorders, but their effects on the reparative capacity of the dental pulp are unknown. This study evaluated the influence of selected immunosuppressive drugs on pulpal tissue healing after direct pulp capping of mechanically exposed dog's teeth with mineral trioxide aggregate (MTA). METHODS: Ten healthy male dogs were assigned into 5 experimental groups: a control group in which no drug was received and 4 experimental groups in which the immunosuppressive drugs prednisone, mycophenolate mofetil, sirolimus, and cyclosporine A were administered 45 days before the operative procedures and until the dogs were killed. Class V cavities were prepared on the buccal surfaces of 12 teeth in each dog. In each cavity, the pulp was exposed and capped with MTA. The pulpal tissue responses to capping material were assessed 65 days postoperatively. RESULTS: Compared with the control group, variable responses was recorded in the groups treated with mycophenolate mofetil, sirolimus, and cyclosporine A, which were characterized by moderate to severe inflammatory reactions, tissue necrosis, and total absence of hard tissue bridging. Pulpal tissue responses in the group treated with prednisone were characterized by inflammatory cell infiltration, limited tissue necrosis, as well as partial to complete hard tissue bridging. CONCLUSIONS: From these findings, it seemed evident that acceptable repair of the dentin-pulp complex, eg, wound healing with hard tissue formation after capping with MTA, is unlikely with mycophenolate mofetil, sirolimus, or cyclosporine A immunosuppressive drug therapy.

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.