Journal of Dental School
Volume:41 Issue: 3, Summer 2023

Fixed orthodontic retainers are pivotal in determining the success of treatment outcomes. However, the bonding materials utilized in their construction are not completely inert. These materials may release bisphenol A (BPA), a compound associated with various health risks. This study aimed to evaluate the cytotoxicity of potential bonding agents used in fixed orthodontic retainers.

In this experimental study, human gingival fibroblasts were cultured and subjected to various dental materials. These materials included acrylic resin (representing removable retainers), Transbond LR, and Enlight LV (which are common adhesives for fixed retainers), as well as Gradia Direct, Direct Flo, and Herculite XRV (commonly used in restorative composites). A control group was also exposed to normal saline. Discs measuring 0.5×1×1 mm were prepared from these materials. The viability of the fibroblasts was assessed using the MTT assay, and a statistical analysis (one-way analysis of variance) was conducted to compare the groups at a significance level of 0.05.

The results of statistical analysis indicated no significant difference between the groups in terms of cytotoxicity for human gingival fibroblasts (p= 0.71).

 None of the tested materials negatively impacted the viability of human gingival fibroblasts. These results provide valuable clinical insights, reassuring orthodontic practitioners about the safety profile of these commonly used materials in the context of fixed orthodontic retention and restorative procedures.

Artificial intelligence (AI) technologies in orthodontics improve accuracy and personalization, automating tasks such as identifying reference points in cephalograms, assessing skeletal age, and predicting treatment needs. Treatment planning is streamlined, reducing duration and enhancing outcomes. Machine learning enables virtual exploration of treatment options and prediction of tooth movement. AI visualization tools improve patient communication. Ethical considerations and patient privacy are important. AI complements orthodontists' expertise, resulting in personalized plans and improved outcomes.

 Although dental caries is the most common chronic oral disease globally, there is no comprehensive plan for preventing this microbial disease. Streptococcus mutans is one of the essential causes of dental caries. Owing to the adverse effects associated with antibiotics, researchers are focusing their efforts on the development of antimicrobial compounds derived from medicinal plants. This study aimed to investigate the antimicrobial effects of the ethanol extract derived from the leaves of Myrtus communis on S. mutans.

 In this in vitro study, the researchers initially procured the Myrtus communis extract. Subsequently, they determined its dry weight and evaluated its antimicrobial activity utilizing the well-dilution method. The antimicrobial efficacy was determined by measuring the minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), and the inhibition zone diameter surrounding the extract. Ultimately, the data were examined using the Mann-Whitney test. Differences less than (P<0.05) was significant statistically.

 The MIC and MBC of the extract for S. mutans were found to be 5 mg/mL and 10 mg/mL, respectively. Chlorhexidine, used as a positive control, exhibited the same values. Furthermore, the diameter of the inhibition zone around both the extract and chlorhexidine was measured to be 17±1 mm and 15±1 mm, respectively. The difference between these measurements was not statistically significant (P=0.077).

 The ethanol extract from the myrtle leaves was as efficient as chlorhexidine mouthwash against S. mutans. Further investigations are needed into the antibacterial effects of different medicinal plants on cariogenic microorganisms.

 Having knowledge of root canal morphology is a crucial requirement for effective treatment. Taking into account the impact of factors such as age, gender, and race on the diversity of root canals in teeth, this study aimed to investigate the prevalence of middle mesial (mid-mesial) canals and isthmus in mandibular first and second molars in a specific subpopulation of Tabriz patients. Cone-beam computed tomography (CBCT) was used for this investigation.

 CBCT radiographs of 215 patients were examined to determine the presence of the mid-mesial canal and isthmus in mandibular first and second molars without endodontic treatment based on gender. All samples were obtained from the Faculty of Dentistry, Tabriz University of Medical Sciences, in 2019. The obtained results were analyzed using SPSS version 16, employing a chi-square test (P < 0.05).

 On the left mandibular side, twenty-eight samples (13%) exhibited a mid-mesial canal in both the first and second molars. On the right side, these values were 29 (13.5%) and 47 (21.9%) for the first and second molars, respectively. Regarding the frequencies of isthmus in mandibular first and second molars, the values were 2 (0.9%) and 18 (8.4%) on the right side and 5 (2.3%) and 21 (9.8%) on the left side, respectively (P-values = 0.147, P = 0.938, P = 0.193, and P = 0.713 in left first, left second, right first, and right second mandibular molars, respectively, which were insignificant).

 This study revealed a low prevalence of mandibular first and second molars with mid-mesial canal and isthmus. The left and right sides and gender did not influence this prevalence.

The canalis sinuosus (CS) is an auxiliary canal that encompasses the anterior superior alveolar nerve, artery, and vein. Understanding the location of this neurovascular structure during surgery can help prevent severe complications. This study aimed to assess the frequency, location, and classification of the CS using CBCT images.

CBCT images of 200 patients were examined considering factors, such as age, sex, presence of impacted teeth, the diameter of the canal’s orifice, and the location of the CS. In sagittal images, the distance from the CS to the buccal cortex, nasal floor, and alveolar crest was measured. Statistical analyses were conducted to compare variables between males and females, as well as between the right and left sides. The Chi-square, Fisher’s exact test, Wilcoxon test, paired t-test, and Kruskal-Wallis tests were utilized for data analysis at a significance level of 5%.

The CS was detected in 135 cases (67.5%) on both sides, while it was not visible in 19 cases (9.5%). In 46 images (23%), the CS was observed only on one side. The canal was most commonly located in the lateral incisor region, followed by the canine area. The average distance from the canal’s orifice to anatomical landmarks, such as the alveolar crest, buccal cortex, and nasal floor, was greater in males than in females. However, this difference was not significant between the right and left sides (P=0.56, P=0.31, P=0.98; respectively). When comparing males and females, no significant differences were observed in the occurrence of CS(P=0.728), the diameter of the canal(P=0.114), the buccopalatal position of the CS(P=0.800), or the canal location within the arch(P=0.132).

It appears that CBCT and other 3D imaging techniques are essential for detecting the CS prior to performing surgery in the anterior maxillary region.

Tooth impaction refers to the failure of a tooth to properly emerge in its expected position within a given timeframe. Several local factors influence the occurrence of tooth impaction, one of which is the specific morphometric characteristics of the mandible. The objective of this study is to examine the association between these factors and the type of impaction observed in the mandibular third molar.

In this Cross-sectional study, 186 impacted mandibular third molar from patients with 20 to 30 years of age were evaluated. The mandibular third molars were categorized according to Pell and Gregory classification into A (third molar is at the same level as the occlusal plane of the second molar), B (third molar is between the occlusal plane and Cementoenamel junction (CEJ) of the second molar) and C (third molar is below the CEJ of the second molar) groups. The Chi-square test was used for statistical analysis of the data. The relation between gonial angle and ramus height with third molar impaction type was assessed using a Pearson correlation test.

The mean±SD for gonial angle in A, B and C groups were 121.05±6.33, 120.24±5.43 and 119.67±5.17 respectively. The mean±SD for ramus height in A, B and C groups were 58.51±5.01, 57.63±5.14 and 57.38±4.51 respectively. There was no significant relation between mandibular third molar impaction type and gonial angle and ramus height (P>0.05).

There was no significant relationship between the gonial angle and ramus height and the type of mandibular third molar tooth impaction according to Pell & Gregory classification as well as eruption and impacted state of mandibular third molar. The results of this study can be used by dentists to assess the difficulty of mandibular third molar extraction prior to their surgeries.

The use of shark cartilage as a supplementary treatment has a long yet unresolved history in the realm of complementary-alternative medicine. This study aimed to investigate the impact of concentrated and purified extracts from Persian Gulf shark cartilage (PGSC) on oral cavity squamous cell carcinoma (SCC) (specifically, the KB cell line) induced in an animal model.

Ectopic tumors of oral cavity SCC were induced in eight nude mice through the heterotransplantation of the KB cell line. Once the tumor volume reached 100 mm3, the mice were randomly divided into two groups: treatment and control. The treatment group received shark cartilage at a dosage of 50 mg/kg body weight, while the control group received a phosphate buffer. The drug was administered daily for four days via the intraperitoneal route. Following this, the drug administration was halted for a period of five days before resuming (as per the NCI protocol). After 54 days, the animals were sacrificed, and their tumors were sent for immunohistochemical evaluation using Ki-67 and CD34 markers.

The findings revealed a significant reduction in intratumoral blood vessels in the treatment group compared to the control group (P-value = 0.001). While there was a decrease in both the size of the tumor and the proliferation of tumor cells, this reduction was not statistically significant. The average proliferation index was 13.33% for the treatment group and 33.33% for the control group.

 Significant decrease in intra-tumoral vascularity can control tumor spreading and metastasis, potentially playing an important role in cancer management of oral cavity SCC.

The use of telephone surveys to explore people's oral health and its determinants is gaining popularity around the world. In Iran, several oral health surveys have been carried out using telephone interviews, each providing unique perspectives on the subject. This study aimed to examine the context, methodology, and findings of these surveys.

A comprehensive search was conducted on online databases, such as PubMed, Google Scholar, MagIran, and IranMedex, supplemented by a free online lookup, to find available oral health studies in Iran involving telephone interviews up to June 2023. The literature was investigated with respect to the background setting, study design, outcomes, and other pertinent content.

 Thirteen papers, both published and unpublished, from eight studies were identified, spanning from 2006 to 2023. The primary target groups were predominantly the entire adult population of the respective cities. All studies that mentioned their call settings used fixed telephone lines. The calculated sample sizes ranged from 368 to 1475, with the number of participants varying from 302 to 1475. The ratio of completed interviews to answered calls fluctuated between 41% and 100%. A significant disparity was noted in the reporting of sample size calculations and response rates among the studies included.

 A relatively small number of oral health surveys have been conducted via telephone in Iran. The reported benefits and disadvantages of using phone calls for interviews suggest that the advantages outweigh the drawbacks, thus garnering interest in using this method in the country. It is recommended that the design of these studies follow a clear and comprehensive approach, thereby facilitating easier interpretation, comparison, and decision-making