Dental Research Journal
Volume:20 Issue: 9, Sep 2023

Similarity in the appearance of a monolithic restoration with the adjacent teeth is necessary. This study aims to influence the foundation material type and ceramic thickness on the final color of zirconia‑reinforced lithium silicate (ZLS) ceramic.

In this experimental study, the A2 translucent blocks of ZLS were sectioned into rectangular specimens with thicknesses 1, 1.5, and 2 mm (n = 15). Substructure materials include resin composite (B1, D2, A2, A3, and C3), nickel chrome alloy, amalgam, and white and black substrate. Substructure material of resin composite with A2 color was proposed as the control group. The value of the color difference (ΔE00) is calculated by the CIEDE2000 formula. Data analysis was accomplished by two‑factor repeated measures ANOVA and one‑sample t‑test (α =0.05).

The mean value of maximum ΔE00 with a black substrate (12.13 ± 0.17) at 1 mm ceramic thickness and the mean value of minimum ΔE00 with B1 resin composite foundation material (0.02 ± 0.17) at 2 mm ceramic thickness are visible. The significant effect of the foundation restoration type, thickness, and interaction between them is visible on ΔE00 (P < 0.001).

Different thickness is required to meet ideal esthetic outcomes with different substrates. Under the conditions of this investigation, zirconia‑reinforced lithium silicate over black, white, nickel–chromium, and amalgam did not meet acceptable outcomes.

Charcoal in the composition of some kinds of toothpaste has created concerns regarding abrasiveness and subsequent complications. Considering the popularity of charcoal toothpaste, and the manufacturers’ claims that no porosity is caused by activated carbon, this study aimed to compare the effects of two charcoal kinds of toothpaste and three conventional tubes of toothpaste on enamel surface roughness of permanent primary teeth.

This in vitro experimental study evaluated 75 teeth mounted in acrylic resin. Teeth were divided into five groups (n = 15). The primary surface roughness of teeth was measured by a profilometer. The teeth were then subjected to wear test in a V8 cross‑brushing machine with Bencer and RP charcoal toothpaste, Crest 7, Colgate Optic White, and Bencer fresh mint toothpaste. After rinsing and drying specimens, their secondary surface roughness was measured. The mean changes in the roughness profile of specimens were analyzed by a one‑sample Kolmogorov–Smirnov test at a 0.05 significance level.

There was no significant difference in the mean surface roughness of specimens before and after the wear test (P > 0.05). The difference in the mean wear of five types of toothpaste was not significant either (P = 0.597). The mean changes in surface roughness were 0.0685 μm for Bencer charcoal, −0.0620 μm for RP charcoal, 0.0765 μm for Crest 7, 0.1137 μm for Colgate Optic White, and 0.1052 μm for Bencer fresh mint toothpaste.

Numerous kinds of toothpaste investigated in this study did not reveal any difference in terms of wear index; however, more studies are needed to evaluate the effectiveness and efficiency of these types of toothpaste.

The retention of cement‑retained implant‑supported restorations can be affected by surface treatments such as anodizing. This study aimed to assess the effect of the anodization of titanium abutments on their tensile bond strength to implant‑supported lithium disilicate (LDS) all‑ceramic crowns.

This in vitro, experimental study was conducted on 26 straight abutments in two groups of anodization and control. In the anodization group, seven flat 9 V batteries connected in series were used to generate 64 V energy. A glass container was filled with 250 mL of distilled water, and 1 g of trisodium phosphate was added to it to create an electrolyte solution. The anode was then disconnected and the abutment was rinsed with acetone and deionized water. The surface roughness of abutments was measured by a profilometer. The abutments were scanned by a laboratory scanner, and maxillary central incisor monolithic crowns were fabricated by inLab SW18 software. The crowns were seated on the abutments and temporarily cemented with TempBond. They were then incubated in artificial saliva and subjected to 5000 thermal cycles. The tensile bond strength of crowns was then measured. Data were analyzed by the Student’s t‑test and Mann–Whitney U‑tests (α =0.05).

The mean bond strength was significantly higher in anodized abutments (P = 0.003). The surface roughness of anodized abutments was slightly, but not significantly, higher than that of the control group (P > 0.05). The frequency of adhesive failure was almost twice higher in anodized abutments.

Anodization of titanium abutments significantly improved their tensile bond strength to implant‑supported LDS all‑ceramic crowns.

This study compared the effect of various grafting materials on the area and volume of minerals attached to dental implants.

In this animal study, 13 dogs were divided into three groups according to the time of sacrificing (2 months, 4 months, or 6 months). The implants were placed in oversized osteotomies, and the residual defects were filled with autograft, bovine bone graft (Cerabone), or a synthetic substitute (Osteon II). At the designated intervals, the dogs were sacrificed and the segmented implants underwent micro‑computed tomography analysis. The bone‑implant area (BIA) and bone‑implant volume (BIV) of bone and graft material were calculated in the region of interest around the implant. The data were analyzed by two‑way analysis of variance (ANOVA) at P < 0.05.

There was no significant difference in BIA and BIV between the healing intervals for any of the grafting materials (P > 0.05). ANOVA exhibited comparable BIA and BIV between the grafting materials at 2 and 4 months after surgery (P > 0.05), although a significant difference was observed after 6 months (P < 0.05). Pairwise comparisons revealed that BIA was significantly greater in the autograft‑stabilized than the synthetic‑grafted sites (P = 0.035). The samples augmented with autograft also showed significantly higher BIV than those treated by the xenogenic (P = 0.017) or synthetic (P = 0.002) particles.

All graft materials showed comparable performance in providing mineral support for implants up to 4 months after surgery. At the long‑term (6‑month) interval, autogenous bone demonstrated significant superiority over xenogenic and synthetic substitutes concerning the bone area and volume around the implant.

Horizontal condylar guidance (HCG) is registered by protrusive interocclusal records but in nonarcon articulators, these records can affect the accuracy. The present study aimed to evaluate the effect of a novel rotation coordinating device (RCD) on condylar guidance setting with protrusive interocclusal records.

The study was designed as a comparative in-vitro investigation. Stone maxillary and mandibular casts were mounted on a fully adjustable instrument as the patient. Duplicate casts were mounted on an arcon and a nonarcon articulator with corresponding face bow records and in maximum intercuspation relation. Five different condylar guidance inclinations for both sides (20°, 30°, 40°, 50°, and 60°) were set on the fully adjustable instrument and 16 protrusive interocclusal records were established at each setting. HCG was set for arcon, nonarcon articulators, and nonarcon articulators with RCD. Data were analyzed using one‑sample t‑test to compare with actual HCG and one‑way analysis of variance (α =0.05).

Mean HCG for studied articulators was 35.40 for arcon, 30.31 for nonarcon without RCD, and 35.61 for nonarcon with RCD which were significantly different from actual HCG (P < 0.05). HCG of the nonarcon with RCD showed no significant difference with arcon articulator (P = 0.71) while both were significantly different from nonarcon without RCD (P < 0.001).

“The RCD” compensates the condylar guidance inclination difference between arcon and nonarcon articulators. The device precisely transfers the hinge movement of the upper member of the articulator to the condylar track.

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer with heterogeneous molecular pathogenesis. Oral lichen planus (OLP) is demonstrated potentially can transfer to OSCC malignant lesions. Unfortunately, there are no definitive prognostic and predictive biomarkers for the clinical management of OSCC patients. The present research is the first study that compared an oral premalignant lesion such as OLP to malignant lesions like OSCC for NOTCH1 expression levels to better understand its oncogenic or tumor suppressive role.

In this cross‑sectional study, mRNA expression of NOTCH1 was evaluated by quantitative polymerase chain reaction in 65 tissue‑embedded Paraffin‑Block samples, including 32 OSCC and 33 OLP. Furthermore, we collected demographic information and pathological data, including tumor stage and grade. The association between NOTCH1 and GAPDH gene expressions was determined by Chi‑squared, Spearman, and Mann–Whitney tests. A P < 0.05 was considered statistically significant for all statistical analyses.

Comparison of OSCC and OLP groups showed a statistically significant difference between the quantitative expression of the NOTCH1 gene (P < 0.001). Qualitative gene expression was divided into low expression and high expression. Both study groups demonstrated a statistically significant gene expression difference (P < 0.001). There was a statistically significant difference between age and NOTCH1 expression in the OLP group (P = 0.036). There was no correlation between NOTCH1 expression and age, gender, tumor grade, and stage.

Since the OSCC is a malignant lesion and the OLP showed the possible nature of malignancy transformation, we can consider the NOTCH1 as a biomarker for the assessment of the tumorigenesis process with a definition of a standard threshold for potentially malignant lesions and malignant OSCC tumors.

A successful endodontic treatment requires a comprehensive knowledge of the root canal morphology. This study compared the diagnostic accuracy of cone‑beam computed tomography (CBCT) and the sectioning technique for the assessment of mandibular first molar (MFM) root canal morphology.

In this in vitro, experimental study, 48 eligible MFMs were mounted in 12 blocks (groups of 4) made of acrylic resin and sheep bone powder and underwent CBCT. Next, the teeth were mounted in transparent self‑cure acrylic blocks, and their roots were sectioned at three points with 3 mm intervals. Images underwent multiplanar reconstruction in NNT Viewer software and were analyzed by one radiologist with the cooperation of an endodontist. The sections were also evaluated by an endodontist under a stereomicroscope (gold standard). The frequency and percentage of single‑canal, and two‑canal roots were determined by each technique. The agreement between CBCT and the Gold standard was analyzed by calculating the kappa coefficient (P < 0.05).

The diagnostic accuracy of CBCT for the assessment of the MFM root canal morphology was 80% on the mesial surface, 99% in the distal surface, and 96% in total. In the mesial surface, 94.2% of two‑canal roots and 66.7% of single‑canal roots were correctly detected by CBCT. These values were 100% and 97.4% in the distal surface, and 95.2% and 95.8% in total, respectively. A significant agreement was noted between CBCT and the Gold standard with κ =0.412 for the mesial, 0.939 for the distal, and 0.907 for the total surfaces (P < 0.001).

CBCT can be reliably used for the assessment of the complex root canal morphology of MFMs when other modalities fall short.