Avicenna Journal of Dental Research
Volume:15 Issue: 3, Sep 2023

 Clinical long-term success of bonded restorations is depended to reduce marginal microleakage and the laser application with combination of new bonding systems may play positive role. The aim of this study was comparative evaluation of Er,Cr:YSGG and Nd:YAG lasers effect on microleakage of class V composite resin restorations using several universal adhesives.

 In this in vitro study, standard class V cavities were prepared on both lingual and buccal surfaces of 72 intact premolar teeth. For evaluation of microleakage, the cavities were divided into 9 groups according to conditioning method (n=15): G1: G-Premio Bond [GP]; G2: Scotchbond Universal Adhesive [SU]; G3: All-Bond Universal [AB]; G4: GP+Nd:YAG Laser; G5: SU+Nd:YAG Laser; G6: AB+Nd:YAG Laser; G7: GP+Er,Cr:YSGG Laser; G8: SU+Er,Cr:YSGG Laser; and G9: AB+Er,Cr:YSGG Laser. The cavities were filled with composite resin and then subjected to thermocycling, placed in methylene blue solutions, embedded in resin blocks and vertically cut in the bucco lingual direction. The microleakage in occlusal and gingival margins was defined as linear penetration of methylene blue and determined with a stereomicroscope to assign microleakage scores using a four point scale. Data were analyzed by using SPSS software and Kruskal-wallis and Mann-Whitney U tests.

 Microleakage scores had statistically significant different before and after laser irradiation in dependent to the adhesive used (P<0.05) but there were no significant different between Nd:YAG and ER,Cr:YSGG laser, also between different universal adhesives (GP, SU, AB). The results showed that total microleakage scores of occlusal margins had significant statistical different in comparison with gingival margins (P<0.001).

 The results indicate that Nd:YAG and Er,Cr:YSGG lasers irradiation, after using the investigated universal adhesives, had a positive effect on reducing the microleakage of composite Class V restorations. The microleakage rate was shown to be independent of adhesives and lasers type used in this study.

 This study investigated the antibacterial properties of four types of tarragon (Artemisia dracunculus) extracts against two caries contributing bacteria, namely, Streptococcus mutans and Streptococcus sobrinus.

 The extracts of A. dracunculus were prepared using n-hexane, ethyl acetate, methanol, and water solvents. In addition, the diameter of inhibition zones, minimum inhibitory concentrations (MICs), and minimum bactericidal concentrations (MBCs) were determined, and finally, MTT (tetrazolium-based colorimetric assay) was used to analyze the cytotoxic effects of the extracts.

 The well-diffusion method showed the antibacterial property of four tested extracts against bacteria. Methanol and water extracts made the highest inhibition zone diameters (P<0.001). This was true for both tested bacteria. The mIC of the methanol, water, n-hexane, and ethyl acetate extracts were 0.78, 1.5, 3.1, and 1.5 mg/mL, as well as 0.78, 0.78, 1.5, and 1.5 mg/mL against S. mutans and S. sobrinus, respectively. The half-maximal inhibitory concentration (IC50) values for methanolic, aqueous, ethyl acetate, and n-hexane extracts were 0.78, 0.78, 1.56, and 3.12 mg/mL, respectively.

 The results provided a rational reason for the traditional use of A. dracunculus extracts against anti-caries-related bacteria. The methanolic extract demonstrated better activity, thus methanol can probably extract a wider range of plant compounds with antibacterial effects.

 The preventive treatments of primary caries lesions are essential for preventing destructive damage to the tooth structure. One of the common treatments is the application of casein phosphopeptide-amorphous calcium phosphate (CCP/ACP) paste on the enamel surface. The aim of this study was to investigate the effect of different percentages of nano-bioactive glass (nBG) incorporation into synthesized CPP/ACP paste on the remineralization of demineralized enamel.

 In general, 24 extracted human intact premolar teeth were selected, and their crowns were removed for this purpose. Each crown was cut into two halves, and each half was considered as a sample. The samples were placed in a demineralizing solution at a pH rate of 4.6 for 8 hours, in artificial saliva for 1 hour, and again in a remineralizing solution at a pH rate of 7 for 15 hours. The pH cycling was performed for 14 days to demineralize the enamel surface. The samples were randomly divided into 3 groups (n=16), including G1 (without treatment), G2 (treated with synthesized CPP/ ACP paste containing 5% nanobioglass), and G3 (treated with synthesized CPP/ACP paste containing 10% nanobioglass). The paste was then placed directly on the surface of the demineralized enamel for 4 minutes (twice a day for 28 days). The samples were subjected to the Vickers microhardness test. Finally, data were analyzed using SPSS (version 19) and the analysis of variance and Tukey’s tests (α = 0.05).

 There was a significant difference between microhardness values in G1 and G2, as well as G1 and G3 (P<0.05). However, no statistically significant difference was observed between G2 and G3 (P>0.05).

 The results showed adding bioactive glass into synthetic CPP/ACP paste increases enamel remineralization in spite of the percentage of bioactive glass incorporation.

One of the advantages of resin composites as a restorative material is their repairability. The purpose of the current study was to compare the repair bond strength of conventional and bulk-fill composites with different bonding systems.

In this in vitro study, sixty cylindrical specimens of materials were prepared according to the six groups under study (two types of conventional Gradia Direct and N-Ceram Bulk-Fill Tetric composites and three bonding systems: Single Bond Universal and Clearfil SE Bond and Single Bond 2). The samples were divided into 6 groups of 10 Single Bond/Gradia Direct composite (G1), Single Bond/Tetric N-Ceram bulk-fill composite (G2), Clearfil SE bond/Gradia Direct (G3), Clearfil SE Bond/Tetric N-Ceram bulk-fill composite (G4), single bond universal/Gradia Direct composite (G5), and Single Bond Universal/Tetric N-Ceram bulk-fill composite (G6). Repair bond strength in each group was measured using the Universal Testing Machine (Hounsfield). All data were analyzed by SPSS 21 using ANOVA, Student’s t-test, and chi-square statistical tests (P<0.05).

The highest and lowest bond strength (15.81±2.44 and 14.02±1.57, respectively) belonged to the Clearfil SE Bond-Tetric N-Ceram and Single Bond (Etch & Rinse)-Gradia Direct groups, respectively. The ANOVA test results demonstrated no significant difference in the bonding strengths of the study groups (P=0.537).

Bulk-fill composite Tetric N-Ceram, apart from the bonding system, had higher repair bond strength compared to the conventional Gradia Direct composite. It seems that self-etch bonding systems (Clearfil SE Bond and Single Bond Universal) have had more bond strength than etch and rinse bonding (Single Bond 2 bonds).

The passivity of the fit may be at risk during the casting as well as the firing of the veneering ceramic. In this study, the comparison of the passivity between computer-aided design/computer-assisted manufacturing (CAD/CAM) implant frameworks and three different conventional techniques before and after applying veneering porcelain was investigated.

In this laboratory cross-sectional study, four groups (n=6) of 3-unit screw-retained implant-supported denture prostheses (ISDPs) were fabricated on a master model with 2 implants. The study groups were as follows: conventional casting with Ni-Cr alloy (group 1), casting with Ni-Cr alloy followed by sectioning and soldering the samples (group 2), double casting with Ni-Cr framework (group 3), and using CAD/CAM-fabricated framework (group 4). All frameworks received porcelain veneer. The one-screw test was performed before and after veneering to measure the vertical misfit at the abutment-framework interface using a stereomicroscope. The mean vertical misfit values were determined at the buccal, lingual, and proximal aspects. The data were analyzed using the Kruskal-Wallis and post hoc tests (α=0.05).

The accuracy of the fit varied significantly before and after veneering among the study groups (P<0.001). Frameworks prepared with CAD/CAM showed lower mean marginal misfit values compared to the other fabrication methods (P<0.001).

Firing the veneering porcelain attached to a screw-retained ISDP may have an adverse effect on the accuracy of the fit. Soft non-pre-sintered CAD/CAM frameworks had better passivity compared to other three conventional methods applied.

 The practice scheme of dentists during the coronavirus disease 19 (COVID-19) pandemic changed markedly around the world. The impacts of these changes on the economic concerns of dentists and the oral health of their patients have been the focus of some recent studies. This study aimed to assess probable alterations in the practice and patient mix of general dentists (GDs) and dental specialists in Isfahan, Iran during the COVID-19 outbreak.

 This analytic cross-sectional study was performed among dentists during the COVID-19 pandemic (April-June 2021). A specific self-administrated questionnaire was designed, the validity and reliability of which were verified by calculating the content validity index and intra-class coefficients (test-re-test techniques), respectively. The questionnaire had 21 items in four sections, including demographic and work characteristics, probable changes in the practice scheme, composition of patients, and the type of the provided treatments. The collected data were analyzed using the SPSS software, descriptive and analytical analysis, including t-test, Chi-square, and ANOVA (α= 0.05).

 Overall, 152 general (response rate= 88%) and 171 specialist dentists were recruited, of whom 206 (63.8%) were males. In addition, 74% of the dentists, especially prosthodontists and restorative specialists, reduced the number of patients per working day (P<0.001). Further, 68.5% reported a decrease in the number of their elderly patients. Based on the results, 77% of the dentists reported an increase in tooth decay and hopeless teeth. Although extraction, emergency treatments, and extensive restorations were increased, prophylactic treatments and follow-ups represented a decline. The highest concern was reported to be about family health (7 out of 10). Finally, prosthodontists, endodontists, and surgery specialists reported the least use of these facilities (P<0.001).

 An increase in the number of hopeless and decayed teeth, as well as an increase in emergency treatments (pain and abscesses) and a decrease in preventive care, confirms an untoward change in the dental practice pattern during the pandemic.

 Higher education faced difficult conditions caused by the coronavirus pandemic after January 2020. In such a situation, education through virtual space was one of the highly important and considerable proposed programs. So far, to our knowledge, no study has compared online and offline virtual education with traditional education in dentistry students. Accordingly, this study compared the efficacy of online and offline virtual training on theoretical knowledge of dentistry students in primary tooth pulp treatment with that of traditional training.

 This semi-experimental study was conducted on dental students who have taken the theoretical pediatrics 2 course in the second half of the academic year 2020-2021. All students were randomly divided into three groups of 20 people, including online and offline virtual training and traditional training (control) groups. Educational contents were delivered to students in the form of an identical PowerPoint for all groups. The PowerPoint slides were prepared and virtual and face-to-face classes were held by the same person (Instructor). In addition, the pre-test and post-test were performed virtually with the same questions (20 questions designed by the instructor). Finally, SPSS-23 was used to describe and analyze the data.

 The participants were 60 students with an average age of 23±0.48 years, including 42 males (70.0%.). No significant difference was observed among groups in terms of gender, age, grade point average (GPA), and pre-test score (P>0.05). The post-test score was significantly higher than the pre-test score (P<0.01), but there was no significant difference in terms of post-test and “post-test-pre-test” scores among the groups (P>0.05). GPA was significantly correlated with the post-test score (P<0.001) and score changes (post-test-pre-test score) (P<0.001).

 It was found that online and offline virtual education are two suitable alternatives for the traditional education of dental students in the primary teeth pulp treatment course.

 The aim of this narrative literature review was clinical indications as well as common complications of the most common treatment options for oral rehabilitation of the upper jaw. The paper also introduced a novel decision-making tool for guiding the selection of the most appropriate treatment for oral rehabilitation based on patients’ residual bone height, width, and quality.

 This study is a review article based on PubMed and Scopus that was done by reviewing articles from 2000 to 2022. Treatment choices for edentulous maxillae with the insufficient bone for implant placement comprise two broad classifications: bone defect compensation by bone augmentation techniques and modified implant designs for specific situations to utilize the remaining bone. The following factors have to be taken into consideration: the residual bony anatomy, remaining bone volume and quality, skeletal maxillomandibular relationship, scientific evidence, the experience of the clinicians, and, the patients’ increasing demands and expectations.

 Grafting techniques are often demanding for both patients and surgeons. Likewise, they are associated with a prolonged treatment time, increased financial cost, and higher complication risks, especially in medically compromised patients. Several non-grafting alternative options have been reported such as zygomatic implants (ZIs), short implants, tilted implants, and the like.

 Oral rehabilitation in the upper jaw should follow a comprehensive assessment and examination of the patient’s quality and dimensions of residual bone. The clinical decision between grafting versus non-grafting options is associated with several factors.

Cellular cannibalism (CC) is a phenomenon during which the tumor cell engulfs other cells, including sibling tumor cells or non-tumor cells such as neutrophils and lymphocytes (known as Xeno-CC). This case report aimed to present CC in three ameloblastomas. Microscopically, hematoxylin and eosin-stained slides of 14 ameloblastoma cases were observed at 400× magnification to identify CC. The findings revealed that 3 cases (21.42 %), including 2 plexiform and 1 follicular ameloblastoma were identified with CC and neutrophil Xeno-CC in stellate reticulum-like cells. Furthermore, a few CC were seen in peripheral ameloblast-like tumor cells. CC has been described as an exclusive morphologic feature of malignancies; however, since it has been reported in benign tumor cells such as ameloblastoma, it seems that this concept needs to be revised. Given the relation between CC and aggressiveness of tumor lesions, this phenomenon can be suggested as one of the predicting factors for aggressive biologic behavior of ameloblastoma.

A dentigerous cyst is a benign and asymptomatic lesion that may become extremely large and then interfere with tooth eruption. Marsupialization is known as the best treatment option for large cysts involving an unerupted permanent tooth. A 16-year-old female has been referred with the chief complaint of an unerupted tooth, extraoral and intraoral swelling, and pain. Radiographic examination demonstrated a unilocular, well-defined, and large radiolucent lesion extended from the distal of the right mandibular canine approximately to the left first mandibular molar. The mandibular left canine was also embedded within the lesion. The selected treatment plan was marsupialization, followed by performing orthodontic treatment of the unerupted mandibular canine. This clinical report presented the successful eruption of an impacted mandibular canine over a 4-years follow-up. The findings of this study revealed that the combination of marsupialization and orthodontic treatment is an effective treatment for large jaw cysts with impacted teeth.