The effect of restorative material selection and cementation procedures on the durability of endocrowns in the anterior teeth: an in-vitro study.

OBJECTIVE: To investigate the fracture resistance and failure modalities of anterior endocrown restorations fabricated employing diverse ceramic materials, and bonded using various cementation methodologies. MATERIALS AND METHODS: Forty maxillary central incisors were divided into two main groups based on the ceramic materials used; GroupI (Zir): zirconia endocrwons (Zolid HT+, Ceramill, Amanngirrbach) and GroupII (E-Max): e-max endocrowns (IPS e.max CAD, Ivoclar Vivadent). Both groups were further split into two subgroups depending on the cementation protocols; subgroup IA "ZirMDP": endocowns cemented with MDP primer + MDP resin cement, subgroup IB (ZirNon-MDP): cemented with MDP primer + non-MDP resin cement, subgroup IIA (E-maxMDP): cemented with MDP primer + MDP resin cement, subgroup IIB (E-maxNon-MDP): cemented with MDP primer + non-MDP resin cement. (n = 10/subgroup). Endocrowns were manufactured using CAD/ CAM. Teeth were subjected to 10,000 thermal cycles. The fracture test was performed at 45o with a palatal force direction until the fracture occurred. Test results were recorded in Newton. The failure mode was examined using a stereomicroscope. A One-way ANOVA test was utilized to compare different groups regarding fracture strength values. Tukey`s Post Hoc was utilized for multiple comparisons. RESULTS: The comparative analysis of fracture strength across the diverse groups yielded non-significant differences, as indicated by a p-value exceeding 0.05. Nonetheless, an observable trend emerged regarding the mode of failure. Specifically, a statistically significant prevalence was noted in fractures localized within the endocrown/tooth complex below the cementoenamel junction (CEJ) across all groups, except for Group IIB, "E-max Non-MDP," where fractures within the endocrown/tooth complex occurred above the CEJ. CONCLUSIONS: Combining an MDP-based primer with an MDP-based resin cement did not result in a significant effect on the anterior endocrown fracture strength. CLINICAL RELEVANCE: Regardless of the presence of the MDP monomer in its composition, adhesive resin cement achieved highly successful fracture strength when used with MDP-based ceramic primers. Additionally, ceramic materials exhibiting elastic moduli surpassing those of dentin are discouraged due to their propensity to induce catastrophic fractures within the tooth structure.

Five-year randomized clinical trial to evaluate the clinical performance of high-viscosity glass ionomer restorative systems in small class II restorations.

OBJECTIVE: Evaluate and compare the 5-year clinical performance of three high-viscosity glass ionomer restorative materials in small class II restorations. MATERIALS AND METHODS: Forty patients, each with four class II restorations, were enrolled in this trial. A total of 160 restorations were placed, 25% for each material, as follows: three high-viscosity conventional glass ionomer restorative systems (Ketac Universal Aplicap, EQUIA Forte and Riva Self Cure HV) and a microhybrid resin composite system (Filtek Z250). Clinical evaluation was performed at baseline and after 1, 3, and 5 years by two independent examiners using FDI criteria. Epoxy resin replicas were observed under scanning electron microscope (SEM) to examine surface characteristics. Data were analyzed with Kruskal-Wallis, Mann-Whitney U, Friedman, and Wilcoxon signed-rank tests (p < 0.05). RESULTS: The success rates were 100% for resin composite, 97.4% for Ketac Universal, and 94.9% for both EQUIA Forte and Riva HV restorations. Statistically significant differences were observed between all groups in terms of surface luster and color match criteria (p < 0.05). Statistically significant changes were found over time for all criteria except for fracture of material, postoperative hypersensitivity, recurrence of caries, tooth integrity, periodontal response, adjacent mucosa, and oral health criteria (p > 0.05). SEM evaluations were in accordance with the clinical findings. CONCLUSIONS: Although drawbacks in surface luster and color match appeared over the 5-year evaluation period, the three high-viscosity glass ionomer restorative materials provided successful clinical performance in small to medium sized class II cavities compared to microhybrid resin composite. CLINICAL SIGNIFICANCE: Glass ionomer restorations exhibited clinical performance similar to that of microhybrid resin composite restorations in small class II cavities subsequent to 5-year evaluation.

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.

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.