Frontiers in Dentistry
Volume:16 Issue: 3, May-Jun 2019

The purpose was to investigate the effect of casein phosphopeptide-amorphous calcium phosphate fluoride (CPP-ACPF) paste, Remin Pro paste, and 0.05% sodium fluoride (NaF) mouthwash on teeth discoloration after home bleaching.

In this in-vitro study, 48 intact and unstained human incisors were divided into four groups (n=12): control (Group 1), CPP-ACPF paste (Group 2), Remin Pro paste (Group 3), and 0.05% NaF mouthwash (Group 4). The specimens were bleached using 20% carbamide peroxide gel for 21 days and were subjected to pH cycling and surface treatment with remineralizing agents for one month. The color of the specimens was determined according to the CIELAB color space at baseline, after bleaching, and after surface treatment. Data were analyzed using one-way analysis of variance (ANOVA), post-hoc least significant difference (LSD) test, and one-sample t-test (P=0.05).

ANOVA showed a significant difference in the mean ΔE of the four groups after surface treatment (P<0.05). Post-hoc LSD test showed a significant difference between the mean ΔE of the control group and those of the treatment groups (P<0.05) with no significant difference between the treatment groups, except for Remin Pro. The mean ΔE and ΔL of the Remin Pro group showed less change than those of the CPP-ACPF and NaF groups, indicating that Remin Pro has the lowest potential for post-bleaching tooth discoloration.

CPP-ACPF paste, Remin Pro paste, and 0.05% NaF mouthwash cause noticeable teeth discoloration immediately after bleaching. Remin Pro has less effect on tooth color than the other two products.

The present study aimed to evaluate the bond strength of heat-cure denture base resin to newly designed Iranian artificial acrylic teeth.

In this in-vitro experimental study, shear bond strengths of Ivoclar acrylic, Apple composite, and B-Star nanocomposite teeth to heat-cure acrylic denture base resin were compared. A total of 18 samples were selected from each group of teeth. The samples were attached to heat-cure resin according to ISO 10477 standard. For the assessment of bond strength, the samples were placed in a universal testing machine and were subjected to shear forces at a speed of 1 mm/minute to record the fracture load. Descriptive statistics, including frequency, mean, and standard deviation, were calculated using SPSS 20 software. Two-way analysis of variance was used to compare the shear bond strength of the groups with and without monomers and the studied artificial teeth.

The mean shear bond strengths of Ivoclar acrylic teeth were 392.22±23.76 MPa and 337.11±32.18 MPa with and without adding monomers to the tooth surface, respectively. The mean shear bond strengths were 250.44±29.84 MPa and 238.33±27.28 MPa (without monomers) and 438.33±24.16 MPa and 311.56±32.78 MPa (with monomers) for Apple composite and B-Star nanocomposite artificial teeth, respectively.

The greatest shear bond strength was attributed to Ivoclar acrylic teeth followed by Apple composite and B-Star nanocomposite artificial teeth. Addition of monomers to the tooth surface significantly strengthened the shear bonding of acrylic base resin to the teeth.

This study aimed to assess the microshear bond strength (MSBS) of Scotchbond Universal adhesive, used in self-etch and etch-and-rinse modes, to primary and permanent dentin at 24 hours and six months.

A total of 88 composite micro-cylinders were divided into eight groups (n=11) as follows: (A) Etch-and-rinse, 24 hours, primary dentin; (B) Self-etch, 24 hours, primary dentin; (C) Etch-and-rinse, six months, primary dentin; (D) Self-etch, six months, primary dentin; (E) Etch-and-rinse, 24 hours, permanent dentin; (F) Self-etch, 24 hours, permanent dentin; (G) Etch-and-rinse, six months, permanent dentin; (H) Self-etch, six months, permanent dentin. The MSBS was measured by a testing machine at a crosshead speed of 0.5 mm/minute. Data were analyzed using three-way analysis of variance (ANOVA).

The mean MSBS was 12.3±2.3 MPa in A, 18.8±4.1 MPa in B, 11.9±3.7 MPa in C, 16±2.9 MPa in D, 19.1±2.7 MPa in E, 22.8±4.1 MPa in F, 16.2±2.6 MPa in G, and 17.2±4.4 MPa in H. In the self-etch mode, the MSBS was significantly higher than that in the etch-and-rinse mode (P<0.001). The MSBS in permanent teeth was significantly higher than primary teeth (P<0.001). At six months, the MSBS significantly decreased in all groups (P<0.001).

The micro-shear bond strength of Scotchbond Universal adhesive decreases over time and depends on the type of tooth and the mode of application of the adhesive.

Color stability of composite resins has a significant role in their durability and clinical service. Considering the increasing use of composite resins and their gradual discoloration, this study aimed to assess the efficacy of Listerine whitening mouthwash for color recovery of two discolored composite resins.

This in-vitro experimental study was performed on 20 samples fabricated of Filtek Z350XT (3M ESPE, St. Paul, MN, USA) and IPS Empress Direct (Ivoclar Vivadent, Schaan, Liechtenstein) composite resins. Primary colorimetry was performed using a spectrophotometer. The samples were immersed in a coffee drink for 7 days. They were then immersed in Listerine mouthwash for 4 minutes daily for 56 days. After this period, the color change of composite resins was reevaluated. Data were analyzed using repeated-measures analysis of variance (ANOVA) and t-test.

The primary color change of Z350XT after immersion in coffee was 1.6 times greater than that of IPS composite (P<0.0001). The color recovery of IPS and Z350XT after immersion in the mouthwash was 1.06±0.58 (P<0.01) and 2.58±1.65 (P<0.001) units, respectively. The color change of Z350XT after exposure to the mouthwash was 25% (1.4 times) greater than that of IPS (P<0.01).

Both composite resins experienced a clinically unacceptable discoloration after exposure to coffee (∆E>3.3). Filtek Z350XT showed greater color change than IPS. Use of Listerine whitening mouthwash caused significant color recovery in both composite resins.

Eradication of Aggregatibacter actinomycetemcomitans (A. action-mycetemcomitans), as an opportunistic periodontopathogen, and inhibition of its virulence factor expression require a new adjunctive therapeutic method. In this study, we accessed the expression level of rcpA gene, as a virulence factor associated with A. actinomycetemcomitans biofilm formation, following treatment by antimicrobial photodynamic therapy (aPDT) using indocyanine green (ICG) doped with chitosan nanoparticles (CS-NPs@ICG).

CS-NPs@ICG was synthesized and examined using scanning electron microscopy (SEM). A. actinomycetemcomitans ATCC 33384 strain was treated with CS-NPs@ICG, as a photosensitizer, which was excited with a diode laser at the wavelength of 810 nm with the energy density of 31.2 J/cm2. Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to determine the changes in rcpA gene expression level.

Synthetized CS-NPs@ICG was confirmed via SEM. The results revealed that CS-NPs@ICG-mediated aPDT could significantly decrease rcpA gene expression to 13.2-fold (P<0.05). There was a remarkable difference between aPDT using CS-NPs@ICG and ICG (P<0.05). The diode laser, ICG, and CS-NPs@ICG were unable to significantly downregulate rcpA gene expression (P>0.05).

aPDT with CS-NPs@ICG leads to a decrease of the virulence factor of A. actinomycetemcomitans and can be used as an adjunct to routine treatments for successful periodontal therapy in vivo.

Internal fit of implant frameworks is an important factor determining the long-term success of dental implant restorations. This in-vitro study aimed to evaluate dimensional changes of implant-supported zirconia frameworks fabricated by two computer-aided design/computer-aided manufacturing (CAD/CAM) systems from scanning to sintering.

A master model of a three-unit fixed partial denture was fabricated with two implant abutments. In each CAD/CAM system (AmannGirrbach and Zirkonzahn), the master model was scanned 12 times, and data were saved as Standard Transformation Language files (scanning groups). Using semi-sintered zirconia, 12 real-size frameworks (milling groups) and 12 enlarged frameworks, were sintered (sintering groups) and made by each system. Dimensions of the master model and frameworks in each phase were measured. Dimensional changes (compared to the master model) were calculated. Data were analyzed using repeated measures analysis of variance, independent t-test, and paired sample t-test (α=0.05).

Comparison of the two CAD/CAM systems revealed that although dimensional changes were greater in the Zirkonzahn system in the milling phase, they were greater in the AmannGirrbach system in the sintering phase. Evaluation of fabrication phases in each system revealed greater dimensional changes in the milling phase compared to other phases in the Zirkonzahn system (P<0.05). However, in the AmannGirrbach system, the values were not significantly different between the milling and sintering phases (P>0.05).

Within the limitations of this study, the results showed that fabrication phases, type of CAD/CAM system, and abutment size had significant effects on dimensional changes.

Temporomandibular disorder (TMD), as a prevalent condition, has been reported to be related to changes in sleep quality. This study aims to assess the association between TMD severities and sleep quality in a selected Iranian population by the application of the Helkimo index and the Pittsburgh Sleep Quality Index (PSQI) questionnaire.

This study comprised 50 non-TMD subjects and 150 TMD patients, which were equally selected from each TMD severity category. The study was conducted at the School of Dentistry, Shiraz University of Medical Sciences, Shiraz, Iran. The patients were first examined and categorized into four TMD severity groups according to the Helkimo index: Non-TMD, mild, moderate, and severe. Then, the patients completed the PSQI questionnaire, which was a standard version translated into Persian and adjusted for Iranian patients.

Comparison of mean PSQI scores of the four groups revealed a significant difference (P<0.001). Pairwise comparisons showed that the severe, moderate, and mild TMD groups and the control received the highest to the lowest PSQI scores (12.26±2.35, 8.20±1.92, 6.88±1.89, and 5.28±1.32, respectively). Similarly, regression analysis indicated that by controlling the effect of demographic variables, the mean PSQI significantly increased as TMD severity increased.

According to the results, all three categories of mild, moderate, and severe TMD patients showed poor quality of sleep in comparison with non-TMD controls. The higher the severity of the disease, the lower the sleep quality.

Calcium hypochlorite (Ca(OCl)2) is currently used as a root canal irrigant. The aim of this study was to compare the effects of calcium hypochlorite and sodium hypochlorite (NaOCl), as root canal irrigants, on the bond strength of posts cemented with a self-adhesive resin cement.

In this in-vitro study, 40 maxillary central incisors with similar root lengths were decoronated. The teeth were randomly divided into five groups based on the irrigant used: Group 1: normal saline (control), Group 2: 2.5% sodium hypochlorite, Group 3: 5.25% sodium hypochlorite, Group 4: 2.5% calcium hypochlorite, and Group 5: 5% calcium hypochlorite. Root canal treatments were performed with Gates-Glidden drills and the irrigant corresponding to each group was used upon changing the file and for irrigating the post space. Then, glass fiber posts were cemented by BisCem self-adhesive cement. After applying 1,000 thermocycles at 5-55°C, three samples of the mid-section of each root were prepared: one for scanning electron microscopy (SEM), and the rest for push-out testing. The results were evaluated using SPSS 23 software according to one-way analysis of variance (ANOVA) and post-hoc Tukey’s test.

The highest and the lowest mean bond strengths were recorded in groups 5 and 1, respectively. There was a significant difference between the 5% calcium hypochlorite group and the other groups (P<0.001). The difference between the other groups was not significant.

The use of 5% calcium hypochlorite with self-adhesive cements increases the push-out bond strength of fiber posts to radicular dentin.

To achieve natural-appearing aesthetic results and for the conservation of tooth structure, it is important for practitioners to be aware of technological advances in materials science as well as the proper use of aesthetic dental techniques. This clinical report describes the restoration of a left maxillary lateral incisor using a one-piece post and core laminate veneer. This proposed restoration technique represents an alternative to traditional restoration procedures, such as metal-ceramic restorations, all-ceramic crowns, and conventional porcelain laminate veneers. It also conserves the remaining tooth structure, reestablishes function, and offers satisfactory aesthetics with the use of adhesive bonding techniques.

The success of nonsurgical endodontic management depends on the complete elimination of infection that compromises the tooth function. Thorough knowledge about the root canal anatomy is one of the principal factors in achieving a successful outcome. The morphology of root canals is not always typical. Maxillary molars, known for varied morphology, require advanced imaging modalities such as cone-beam computed tomography (CBCT). This case report describes a series of four maxillary molars with different forms, numbers, and configurations of root canals and with unusual morphology, including a case of a third mesiobuccal (MB3) canal, a case of a second mesiobuccal (MB2) canal with two palatal canals [mesiopalatal (MP) and distopalatal (DP)], a case of three mesiobuccal canals (MB1, MB2, MB3), three distobuccal (DB1, DB2, DB3) canals, and two palatal canals [mesiopalatal (MP) and distopalatal (DP)], and a case of taurodontism, where different access cavity modifications, diagnostic methods, and magnifications were considered.