Journal of Dental School
Volume:38 Issue: 1, Winter 2020

Objectives

This paper describes the fabrication of a new porous 3D-printed scaffold composed of polycaprolactone (PCL) and polyether-ether ketone (PEEK) micro-particles for bone tissue engineering (BTE) applications.

In order to improve the compatibility of the reinforcing PEEK powder with polycaprolactone, the PEEK powder was surface-modified by an amino-silane coupling agent. After modification, Fourier-transform infrared spectrometry (FTIR) and differential scanning calorimetry (DSC) were used to investigate the chemical reaction between PEEK and silane coupling agent. In order to increase the compressive modulus of the 3D printed PCL scaffold, 10% silane-modified PEEK was incorporated into the PCL polymeric matrix. Scanning electron microscopy (SEM) was used for cell morphology and attachment evaluation.

The results indicated that the silane coupling agent was successfully grafted onto the particle surface. The compressive modulus of PCL scaffold increased by incorporating the silane-modified PEEK, despite having higher porosity, compared with the pure PCL scaffolds. Addition of amino-silane had a positive impact on cell response, and that surface modification led to improved particle dispersion.

In conclusion, it seems that the incorporation of surface-modified PEEK micro-particles into the PCL porous scaffold could enhance its mechanical properties, and may be applicable for the management of large bone defects.Keywords Polyetheretherketone; Polycaprolactone; Amino-propyl-triethoxysilane; Tissue Scaffolds; Printing, Three-Dimensional

This study aimed to assess the effect of head position on linear cephalometric measurements by cone-beam computed tomography (CBCT).

CBCT scans of four human dry skulls were obtained by NewTom 3G volume scanner with alarge (15 x15 cm)field of view in 1 centric and 18 eccentric positions: 10°, 20°, and 30° tilt (right and left), 10°, 20°, and 30° rotation (right and left), 10°, 20°, and 30° extension and 10°, 20°,and 30° flexion. The distances between the selected landmarks namely the Nasion (N), Sella (Se), anterior nasal spine (AN S), Menton (Me), Gnathion (Gn), Gonion (Go), and Condylion (Co) were measured by two observers on maximum intensity projection reconstructions using the NNT Viewer software, and compared with the actual measurements (gold standard). The inter-class correlation coefficient (ICC) and the student’s t-test were used for statistical analysis.

The mean inter-rater agreement was excellent for all head positions (ICC=96.89%). The maximum error in absolute mean measurements was 2.56 mm (P=0.03) The minimum error was for the N-Me line, which is a vertical line closest to the midline.

The greatest error was observed in 30° left ward rotation for the left CoGn linear measurement. Although this level of error may not be of clinical significance, it is suggested that clinicians acquire the scans in ideal head position to minimize distortion and errors.

The aim of this study was to compare the shear bond strength and durability of one/two-bottle All-Bond Universal used in self-etch (SE) and total-etch (TE) modes on dentin discs.

In this in vitro study, 144 human premolars were allocated to 12 groups for use of one-bottle or two-bottle adhesive in SE and TE modes and their assessment at three time points. Dentin discs with 2 mm thickness were prepared. They were polished with 600 and 800 grit silicon carbide abrasive papers. One/two-bottle All-Bond Universal bonding agent was used in SE and TE modes in the groups. Composite resin cylinders were made by the Tygon tubes on the bonding surface and then cured . Shear bond strength was measured by a universal testing machine at 24 h, and 6 and 12 months, and the mode of failure was determined under a stereomicroscope at x10 magnification. Data were analyzed by two-way ANOVA and Bonferroni test.

After 24 h and 6 and 12 months, the micro-shear bond strength was significantly lower in one-bottle SE compared with other groups. The two-bottle TE group showed the highest bond strength (P<0.001). In all groups, the bond strength significantly decreased at 12 months, compared with 24 h (P<0.05).

Two-bottle TE system showed higher bonding durability and bond strength compared with other groups.

Objectives Infection control is one of the most important aspects of dentistry. Since intraoral radiographic films are directly in contact with the oral environment, microbial contamination may transmit infectious diseases. The purpose of this study was to investigate the frequency of microbial contamination of intraoral radiographic films and compare the probable microbial contamination of two intraoral radiographic film brands available in the Iranian market. Methods in this in vitro, experimental study, 900 radiographic films of two commercial brands, i.e. Intra X-ray and Carestream films were placed in aerobic, anaerobic, and fungal culture media immediately after removal from the packaging in sterile conditions. The samples were transferred to the respective culture media after incubation. The cultured bacteria were Gram-stained, and microscopically observed. The percentage of the contaminated intraoral radiographic films and the type of microbial contamination were reported. Data were analyzed using the Chi-square test. Results Of all, 32.6% of the Carestream films and 44.6% of Intra X-ray films were infected by aerobic microorganisms, mostly Bacillus. In the anaerobic culture, the turbidity of the medium indicated the possible presence of microorganisms. In the fungal culture, no fungal hyphae were observed microscopically. Conclusion The results of this study showed that intraoral films cannot be considered sterile. Intra X-ray radiographic films were significantly more contaminated than Care stream radiographic films.

Obstructive sleep apnea (OSA) is a relatively common sleep disorder, which leads to multiple sleep arousals and hypoxemia. We aimed to assess the knowledge and attitude of students and faculty members of Shahid Beheshti Dental School, Tehran, Iran about OSA.

We conducted a cross-sectional study on undergraduate and postgraduate students and faculty members of oral and maxillofacial (OMF) surgery, orthodontics, and oral medicine departments of Shahid Beheshti Dental School. The Obstructive Sleep Apnea Knowledge and Attitude (OSAKA) questionnaire was used to obtain information. We used the Chi-square, Kruskal Wallis, and Mann-Whitney U tests for statistical analysis. The data were analyzed by SPSS 22.0 (α <0.05).

One hundred ninety-seven participants, including 43 dental students, 68 postgraduate students, and 64 faculty members filled out the questionnaire. The mean knowledge score among all participants was 10.69±3.133. Overall, OMF medicine and OMF surgery faculty members had significantly higher correct answer choices in the knowledge section than fifth and sixth-year dental students (P<0.001). There was no significant difference among other groups (P>0.05). About attitude, 91% of respondents reported that OSA is an important or extremely important disorder. However, only 10.2% and 16.9% felt confident about the ability to manage patients with OSA and identifying patients at risk of OSA, respectively. Overall, gender and educational level were correlated with the mean attitude score (P<0.05).

All participants had poor knowledge but a positive attitude towards OSA. This shows the necessity of better education about OSA.

Asparagus officinalis (A. officinalis) extract has several bioactive ingredients. This study assessed the healing effects of A. officinalis methanolic extract.

In this experimental study, after preparing the methanolic extract of A. officinalis with a concentration of 100 , its bioactive ingredients were determined using high-performance liquid chromatography (HPLC) and then its cytotoxicity was assessed using the methyl thiazolyl tetrazolium (MTT) assay. Five experimental groups with 25 samples were assessed as follows: (I)human gingival fibroblast(HGFs) cultured in high-glucose Dulbecco’s modified Eagle’s medium (DMEM), (II) same as group Ibut with 10 μg/mL methanolic extract of A. officinalis, (III) same as group Ibut with 25μg/mL methanolic extract of A. officinalis, (IV) same as group Ibut with 50 μg/mL methanolic extract of A. officinalis, and (V)same as group Ibut with 100μg/mL methanolic extract of A. officinalis. Cell motility in the control group and group Vwas examined quantitatively using the cell scratch assay at 24 h. We used one-way ANOVA and t-test to analyzethe cytotoxicity of A. officinalis extract and the motility of HGFs, respectively.

The MTT assay showed no significant difference in cell viability among the experimental groups (P=0.07). A remarkable cellular wound closure equal to 60.85% was noted after 24 h.

The methanolic extract of A. officinalis with a concentration of 100 μg⁄mL showed significant healing effects on an experimental scratch setup of HGFs.

Spindle-shaped lesions, which include a wide range of reactive lesions from malignant to very invasive, are among the most challenging head and neck pathologies. Herein, we report a case of leiomyosarcoma (LMS) of the mandible for which, immunohistochemistry was performed to find out whether it was a primary or a metastatic tumor.

This case report presents a 23-year-old female with a 3-month history of pain and mild swelling in the anterior mandible. Panoramic radiography and cone-beam computed tomography revealed an osteodestructive lesion in the mandible. The tumor was composed of interlacing fascicles of spindle-like cells with pleomorphism, hyperchromatism, and atypical mitotic figures. Immunohistochemical (IHC) staining revealed that the tumor cells were positive for vimentin, smooth muscle actin (SMA), desmin, and P53 and had negative reactivity for estrogen receptor (ER) and S100. The patient underwent hemi-mandibulectomy with immediate reconstruction via a microvascular fibula flap. The patient died 15 months after surgery due to metastasis to the right pleura.

Primary LMS of the jaws is rare and can be confirmed by IHC staining

At present, clear aligners are widely used for treatment of complicated orthodontic cases such as severe crowding, and class II or III malocclusion. However, some movements such as extrusion, derotation, torque formation, or closing of large spaces are still challenging to perform with clear aligners. Resin attachments, elastics, some certain gingival margin designs, and thermopliers have been suggested to increase the predictability of tooth movement with aligners. At present, it is well understood that attachments are a non-negligible part of treatment with aligners. Different experimental and clinical studies have assessed these features, but there is still no exact guideline for indications of each feature, or their effectiveness. Thus, the aim of this study was to review in vitro and clinical studies and to discuss the best approach to achieve more predictable tooth movement with clear aligners.

Different databases including PubMed, Google Scholar and Scopus were searched and articles evaluating retention of aligners, different approaches to increase retention, and characteristics of attachments were included in this review.

39 experimental and clinical studies were included for this narrative review.

The composition of aligner material probably plays a more important role than material thickness in retention. However, more comprehensive studies should be performed to confirm this. There is no doubt upon the necessity of using attachments to increase the retention of aligners and predictability of tooth movements. It seems that rectangular attachments are more efficient than ellipsoid ones. Also, quarter-sphere shaped attachments are preferred for rotational and root movements.