Journal of Dental School, Shahid Beheshti University of Medical Sciences

Evaluation of Shear Bond Strength and Antimicrobial Effects of Resin-Modified Glass Ionomer Containing Titanium Oxide and Silver Nanoparticles

Abdolrahim Davari — 2023-01-18

Objectives Streptococcus mutans, as one of the most important cariogenic bacteria, is responsible for dental caries. To prevent and control dental caries, it is reasonable to use new materials and techniques for eradicating cariogenic bacteria. The present study aimed to evaluate and compare the antimicrobial effects of resin-modified glass ionomer (RMGI) containing silver and titanium oxide nanoparticles, on Streptococcus mutans (S. mutans) and to assess and compare the shear bond strength between coronal and radicular dentins.

Methods This study investigated the antibacterial properties of 16 RMGI discs, containing 3 weight percent (wt.%) of silver and titanium nanoparticles prepared for each group. Also, the shear bond strength of RMGI discs containing nanoparticles between the coronal and radicular dentins were compared. Kolmogorov-Smirnov test was used to evaluate the normal distribution of data. Normally distributed data were analyzed and compared between the groups, using two-way ANOVA test; otherwise, Kruskal-Wallis test was performed to analyze the data. The level of statistical significance was set at 0.05.

Results The mean colony count of S. mutans significantly reduced in both silver and titanium nanoparticle groups after 15 days compared to one-hour and 24-hour intervals (P<0.0001). The shear bond strength test revealed no significant differences between the two experimental groups (P>0.05).

Conclusion Incorporation of silver and titanium oxide nanoparticles at a concentration of 3 wt.% yielded optimal antibacterial characteristics, without causing any significant changes in the shear bond strength. Comparison between nanoparticle containing RMGI and RMGI showed that over time it has more ability to create antibacterial properties against S. mutans bacteria.

Effects of Smoking Cessation Counseling Based on the Stages of Change Model in a Dental School Setting: A Semi-Experimental Study

Zahra Ghorbani — 2023-02-01

Objectives The present study aimed to evaluate the effects of smoking cessation counseling by a dentist on the smokers’ preparation for change to quit smoking.

Methods This study was performed on 150 smokers, admitted to the Dental School of Shahid Beheshti University of Medical Sciences, Tehran, Iran. The patients were randomly divided into two groups of 75 participants. The intervention group received smoking cessation counseling by a single senior dental student for 30 min session. The patient’s status in the stages of change was determined at baseline and after the intervention. For statistical analysis, paired t-test, Mann-Whitney U test, and multivariate linear regression analysis were performed at a significance level of P<0.05.

Results At baseline, there were no significant differences between the intervention and control groups in terms of the stage of change for smoking cessation. Also, there was no significant difference in the stages of change in the control group between the baseline and one-month follow-up. However, this difference was significant in the intervention group (P=0.006). In other words, the number of patients in the pre-contemplation stage decreased by 43%, the number of patients in the contemplation stage increased by 20%, and the number of patients in the action stage increased by 16%.

Conclusion It can be concluded that smoking cessation counseling enhances a person’s forward movement and transition through the stages of change for smoking cessation

Effect of Post Construction Alloy Type (NPG and Ni-Cr) and Cement Type on Fracture Resistance of Endodontically Treated and Restored Teeth by Cast Post-Core

Alireza Hadi — 2023-01-28

Objectives It is claimed that non-precious gold (NPG) alloys with modulus of elasticity (MOE) very close to dentin’s MOE can enhance the fracture resistance of endodontically treated teeth. Since limited studies have been conducted on these alloys, in this study, we tried to investigate the effect of cast alloys with MOE close to dentin and also the use of resin and zinc phosphate cement on the fracture resistance of endodontically treated teeth.

Methods Forty mandibular single canal premolar teeth were assessed after post space endodontic treatment and preparation. The samples were randomly divided into four groups: Group A: Ni-Cr alloy + zinc phosphate cement, group B: Ni-Cr alloy + resin cement (Panavia^® F2), group C: NPG alloy + zinc phosphate cement, and group D: NPG alloy + resin cement (Panavia^® F2). The force needed for fracture and the fracture pattern of each tooth were recorded. The Shapiro-Wilk test was used to examine the normality of data distribution, Levene’s test was used to examine the equality of variances, and Fisher’s test was used to examine the equality of qualitative variables in the groups.

Results A statistically significant difference was observed between the two post-core construction alloys (P<0.0001) and also between the two types of cement used (P<0.001). However, the interaction between alloy and cement type was insignificant (P=0.144). NPG alloy and Panavia^® F2 cement showed better results than the other groups.

Conclusion The NPG alloy + Panavia^® F2 cement technique is preferred in reconstructing endodontically treated teeth.

Dexamethasone-loaded PLGA Microspheres in Calcium Phosphate Cements for Bone Regeneration: Physicochemical Characterization

Fatemeh Karim-Aghaloo — 2023-02-01

Objectives Bone regeneration is one of the most challenging issues in medicine, for which researchers have been seeking new practical strategies. Calcium phosphate cements (CPCs) are proper candidates for bone scaffolds due to their high biocompatibility, self-setting features, and similar mineral content to the bone.

Methods The present study aimed to fabricate composite CPC/ dexamethasone-loaded PLGA microsphere scaffolds, which significantly affected tissue remodeling, and to determine their potential for bone regeneration purposes. The SEM images were used to study the microstructure of the fabricated scaffolds and to investigate the distribution of PLGA in CPC. Moreover, FTIR analysis was performed to determine the chemical components of the fabricated scaffold and to approve the presence of dexamethasone and PLGA in the composite scaffolds. Next, ultraviolet spectroscopy was used to determine the amount of dexamethasone released over time.

Results The FTIR results confirmed the presence of dexamethasone in the scaffold. Moreover, the cement/dexamethasone-loaded PLGA scaffold had a lower drug release compared to pure PLGA. Besides, a higher level of PLGA loading led to an increase in the drug release rate.

Conclusion According to the results, different weight percentages of dexamethasone-loaded PLGA microspheres incorporated into CPC showed differences in the release time.

Assessment of Sterility and Residual Solvents Agents in Antler-derived and Bovine Xenograft Bone Substitutes: An In-vitro Study

Ardeshir Lafzi — 2023-02-01

Objectives This study aimed to assess and compare the results of sterility and residual solvent testing in a newly developed antler-derived xenograft versus a bovine-derived xenograft.

Methods First, test and control samples were prepared using thermal and chemical procedures, involving immersion in deionized water for 24 hours, drying, boiling in sterile water, chemical treatment with chloroform and methanol, and heating at 650°C in a furnace. Next, they were sterilized via gamma radiation at 25 kGy. The sterility test was then performed based on the ISO 11737-2:2019 standard, using the direct inoculation method. Finally, residual solvent testing was carried out via gas chromatography-mass spectrometry.

Results The sterility test showed no evidence of bacterial or fungal growth in any of the samples during 14 days of incubation. Also, residual solvent testing indicated no sign of residual solvents in the samples.

Conclusion Antler-derived xenograft was safe to use in terms of the sterility and removal of residual solvents. Further studies should be carried out regarding other important laboratory tests as well as the animal and clinical studies.

Effects of Social Media on People’s Tendency Toward Aesthetic Dental Treatments

Saeed Madihi — 2023-01-16

Objectives This study aimed to investigate the impact of social media on people’s tendency toward aesthetic dental treatments in Iran.

Methods This cross-sectional study was performed on 410 individuals, including dentists or dental students and laypeople, who were selected via convenience sampling. A questionnaire, consisting of sociodemographic characteristics, frequency of social media use, tendency toward aesthetic dental treatments, and factors affecting people’s decisions, was completed for data collection. This online questionnaire was created using the Porsline^© website and posted on social media. The collected data were analyzed in SPSS version 21, using Chi-square test. A P-value less than 0.05 was considered statistically significant.

Results Of 410 participants, 157 (38.3%) were dentists or dental students. Only 38.2% of the participants in the dentist group were willing to receive aesthetic dental treatments, whereas laypeople were significantly more inclined to receive such treatments (69.2%) (P<0.001). Almost half of people who used social media platforms several times a day and also 71.8% of people who used social media once a day or less showed tendency toward aesthetic dental treatments (P=0.01).

Conclusion Based on the results, the time spent on social media was not significantly associated with people's tendency to receive aesthetic dental treatments. Also, dentists were less interested in such treatments for themselves.

Cutaneous Metastatic Undifferentiated Carcinoma to the Mandibular Gingiva: A Rare Case Report

Dr.Saede Atarbashi Moghadam — 2023-02-05

Objectives Metastasis to the oral cavity is a rare phenomenon. Basal cell carcinoma (BCC) is the most common skin malignancy, followed by squamous cell carcinoma (SCC) and melanoma. Nevertheless, BCC rarely metastasizes, and most cases of cutaneous metastasis to the oral cavity include melanoma and SCC. Oral metastatic lesions are not typical differential diagnoses and may cause diagnostic challenges.

Case In this paper, we present the case of a 36-year-old female patient with a rapidly growing gingival mass. She had a history of undifferentiated skin carcinoma almost 18 months ago. An incisional biopsy was performed, and according to microscopic findings and medical history, a diagnosis of undifferentiated metastatic carcinoma was made.

Conclusion Oral metastasis needs to be considered in the differential diagnosis of lesions in patients with a history of malignancy.

Extremely Large Mental Foramina in a Rare Case of Oral Hemangiolymphangioma

Mitra Ghazizadeh Ahsaie — 2023-02-05

Objectives Hemangiolymphangiomas (HLAs) are rare vascular malformations of lymphatic and blood vessels. These lesions commonly occur in the head and neck regions. In this paper, we describe a rare case of HLA, with significant effects on the mandibular bone and neurovascular canals.

Case A 28-year-old patient with a history of head and neck HLA was referred to an oral and maxillofacial surgeon for dental implant placement. The results of radiographic analysis and cone-beam computed tomography (CBCT) indicated the mandibular bone enlargement, sclerosis, and bone remodeling. The inferior alveolar nerve canal (IANC) and mental foramen were markedly enlarged on both sides. Additionally, multiple soft tissue calcifications were present. The patient was referred to the oral and maxillofacial surgery (OMFS) department for further dental treatment.

Conclusion Patients with maxillofacial vascular malformations require careful radiographic and imaging assessments before any surgical intervention, especially implant placement. Enlargement of neurovascular canals, especially IAN and mental foramen, along with the presence of sclerotic bone, should be considered as important findings, as they may significantly influence the surgical outcomes.