Journal of Dental Research, Dental Clinics, Dental Prospects
Volume:13 Issue: 4, Autumn 2019

This study aimed to compare the in vitro cytotoxicity of Theracal LC, BiodentineTM, iRoot BP Plus, and MTA Angelus on human pulp fibroblasts (HPF).

Fifteen discs from each calcium silicate-based material were prepared in sterile Teflon molds. After setting, the fabricated discs were eluated with a culture medium for 24 h. HPF cells were plated onto 24-well plates at 5×103 cells/well, and the cells were exposed to the material eluates. The cell viability was evaluated with MTT assay at three different times (24, 48, and 72 h). Data were statistically analyzed. The apoptotic/necrotic status of HPF cells exposed to material eluates was determined by flow cytometry.

The differences between the effects of Theracal LC, BiodentineTM, MTA Angelus, and iRoot BP Plus on HPF cells were found to be statistically significant (P<0.05). Theracal LC was found to be more cytotoxic considering other vital pulp capping materials at 24- (28.3%), 48- (44.9%), and 72-hour (49.2%) intervals. On the other hand, BiodentineTM showed the least cytotoxic effects (97.1%, 130.0%, and 103.7%, respectively) According to flow cytometry results, Theracal LC material increased apoptosis/necrosis ratios compared to the other materials.

Based on the results of the present study, BiodentineTM, MTA Angelus, and iRoot BP Plus can be classified as biocompatible materials in vital endodontic treatments. However, the Theracal LC materials should be used carefully due to their cytotoxic effects.

Zirconia restorations with high mechanical properties are the current treatment options for fixed restorations with advantages of high biocompatibility and low pulp irritation. Although the effect of sintering time and temperature on the optical and mechanical properties of zirconia core material were investigated, the effect of these parameters on the translucent monolithic zirconia is still uncertain. This study aimed to evaluate the effect of the changes in sintering temperature and holding time on the mechanical and structural properties of monolithic zirconia.

Totally, 340 self-colored (A2) zirconia specimens from two different monolithic zirconia groups (n=170) were prepared, measuring 15.5×12.5×1.2 mm. Then, 17 subgroups (n=10), including the control groups, were sintered according to sintering parameters. XRD analysis was used to determine phase transformations. The surface roughness of the specimens was evaluated using profilometry, and the flexural strength of the specimens was evaluated by the three-point bending test. The data were analyzed using three-way ANOVA and post hoc multiple comparison test with Bonferroni correction (a=0.05) at a significance level of 0.05. Independent-samples t-test was used to compare the subgroups between the control groups (P˂0.05).

No tetragonal-to-monoclinic phase transformation was observed in the groups. Changes in the sintering parameters did not significantly affect the surface roughness and flexural strength of monolithic zirconia. Surface roughness values for all the subgroups were above the clinically critical limit.

According to the results of this study, changes in the sintering parameters did not affect the surface phase transformation, surface roughness, and flexural strength of monolithic zirconia.

Oral squamous cell carcinoma (OSCC) is among the ten most frequent malignant tumors, with SCC accounting for 94% of oral malignancies. Myofibroblasts and macrophages are multifunctional cells that have a crucial role in the biological behavior of these tumors. This study aimed to comparatively evaluate the frequency of myofibroblasts and macrophages between oral and cutaneous squamous cell carcinomas.

Sixty paraffin blocks, consisting of 20 cases of OSCC, 20 cases of CSCC, 10 cases of normal skin, and 10 cases of normal oral mucosa, were selected for this descriptive-analytical cross-sectional study. To evaluate the prevalence of myofibroblasts, α-SMA staining and CD163 markers for macrophages were used. In this study, the data were analyzed with Wilk-Shapiro test and t-test using SPSS 19. Statistical significance was set at P<0.05.

The mean myofibroblast scores in CSCC and OSCC were 20.05 and 20.95, respectively, with no significant difference between the means (P>0.05). The mean macrophage scores in the skin and oral cavity were 28.125 and 49.67, respectively, with a statistically significant difference (P<0.05), indicating that the mean oral macrophage score was significantly higher than that in the skin. There was no significant difference between the presence and accumulation of macrophages and myofibroblasts between the oral and cutaneous SCCs; however, the intensity of accumulation and color pattern in OSCC and CSCC were higher than those in the normal skin and mucosa (P<0.05).

According to the results of this study, it appears the biological behavior of OSCC and CSCC does not depend on myofibroblasts, and other factors might be involved.

Regeneration of bone defects remains a challenge for maxillofacial surgeons. The present study aimed to compare the effects of octacalcium phosphate (OCP) and the combination of octacalcium phosphate/gelatin (OCP/Gel) on mandibular bone regeneration in rats

In the present study, 36 male Sprague-Dawley rats were used. The animals were randomly assigned to the following experimental groups: OCP (n=12), OCP/Gel (n=12), and the control group (n=12). Defects were created in the rat mandibles and filled with 10 mg of OCP and OCP/Gel disks in the experimental groups. In the control group, however, no substance was administered. Samples were taken on days 7, 14, 21 and 56, respectively, after the implantation. Sections (5 µ) were prepared and stained by H&E. The sections were studied, and the volume fraction of newly formed bone was measured by Dunnett's T3 test based on the significance level (P=0.05).

In the experimental groups, the new bone formation began from the margin of defects 7‒14 days after the implantation. During the healing process, the newly formed bone healed a larger area of the defects and grew structurally. In the control group, the defects were primarily filled with dense connective tissue, and only a small amount of new bone was formed. The present study showed a statistically significant difference in the volume of newly formed bone between the experimental groups and the control group (P<0.001).

OCP/Gel composite can be beneficial in the healing process of mandibular bone defects.

Mesiodistal and buccolingual angulations of teeth are variable in different malocclusion classes. This study aimed to assess the mesiodistal angulation of posterior teeth in orthodontic patients with vertical, normal, and horizontal facial growth patterns.

This descriptive, cross-sectional study evaluated 150 lateral cephalograms of orthodontic patients. According to cephalometric analysis, facial growth patterns were divided into three groups of normal, horizontal, and vertical (n=50). The angulation of maxillary and mandibular posterior teeth was then measured. Data were analyzed using SPSS 22.

The results showed an increase in the mean angle of maxillary and mandibular posterior teeth relative to palatal and mandibular planes in patients with a vertical facial growth pattern. Conversely, their angulation decreased relative to the bisected occlusal plane (BOP). The angulation of posterior teeth decreased relative to palatal and mandibular planes and increased relative to the occlusal plane with an increase in overbite. The mean angle of all maxillary teeth relative to the palatal plane was significantly greater in open bite patients compared to normal and deep bite patients. This value in patients with normal bite was significantly greater than that in deep bite patients (P<0.05).

The current results revealed that in patients with a vertical growth pattern, all the posterior teeth had a forward inclination. Conversely, in patients with a horizontal growth pattern, the teeth had a backward inclination.

Several types of post have been developed for clinical use. A biological dentin post obtained from an extracted tooth eliminates the problems arising from material differences and reduces the fracture rate in teeth undergoing root canal treatment. This study used finite element analysis to compare a biological dentin post with posts made of two different materials.

Three 3D models of the upper central incisor were created, and stainless-steel, glass fiber and biological dentin posts were applied to these models. The restoration of the models was completed by applying a composite as the core structure and a ceramic crown as the superstructure. Using finite element stress analysis in the restoration models, a 100-N force was applied in the vertical and horizontal directions and at a 45º angle, and the suitability of the biological dentin post was evaluated by comparing the data.

Under the applied forces, the greatest stress accumulation was seen in the models with the stainless steel post. Because the stainless steel post was more rigid, stress forces accumulated on the surface instead of being transmitted to the tooth tissue. In the models with the glass fiber and biological dentin posts, the post material responded to the stratification in tandem with the dental tissue and did not cause excessive stress accumulation on the tooth or post surfaces.

The results showed that biological dentin posts prevent the accumulation of stresses that might cause fractures in teeth undergoing root canal treatment. In addition, the physical compatibility and biocompatibility of a biological dentin post with the tooth imply that it is a good alternative to the types of post currently used.

Self-ligating brackets might be more efficient than conventional appliance systems during the initial alignment stage of orthodontic treatment due to reduced frictional resistance. This study aimed to compare the alignment efficiency and pain experience of Damon3 self-ligating and MBT pre-adjusted brackets in the initial alignment stage.

In this randomized clinical trial, 30 patients aged 14‒20 years, who needed non-extraction treatment in both maxillary and mandibular arches, were randomly assigned to two groups; 15 patients were treated with MBT pre-adjusted brackets, and 15 patients received Damon3 self-ligating brackets, both with 0.022-in slots. Alginate impressions were taken at the start of treatment (T0) and four monthly visits (T1, T2, T3, and T4). Little’s irregularity index (LII) was used to assess the tooth displacements. The patients rated their pain experience immediately after the insertion of the archwire, 4 hours, 24 hours, 3 days, 7 days, and at each monthly visit using a visual analog scale (VAS).

The rate of upper dental alignment between T0 and T4 was significantly higher with the Damon3 compared to MBT brackets (P=0.015). Although significantly more changes in the lower LII scores were observed during the first three months with the Damon3 system, the rate of improvement in the irregularity of lower teeth over the 4-month period was not significantly different between the two groups (P=0.50). The patients’ pain experience was not significantly different between the bracket groups (P=0.29).

During the four-month alignment stage, significantly more improvement in the upper dental irregularity was observed with self-ligating compared to conventional brackets. The bracket type had no effect on pain experience during the alignment stage.

The most common problem associated with dental implants is the abutment screw loosening. This research aimed to investigate the effect of the type of connection on screw loosening, using a finite element method (FEM).

Periosave system and different types of the implant–abutment connection were used for modeling. After being measured, CAD files were modeled using CATIA software and imported to the ANSYS analysis software, and the model was loaded.

A force of 100 N was applied at 0.1 second, and no force was applied at 0.42 second. The screw head deformation at 0.1 and 0.42 seconds was 8 and 3.8 μm, and 7.6 and 2.8 μm at morse taper and octagon dental implant connections, respectively. The displacement rate of the internal surface of the abutment at 0.1 and 0.42 seconds was 10.7 and 8.4 μm, and 5.7 and 5.6 µm in the octagon and morse taper dental implant connections, respectively. The displacement of the implant suprastructure–abutment interface from the screw head at 0.1 and 0.42 seconds was 9 and 7 μm, and 7 and 6 μm in the morse taper and octagon dental implant connections, respectively. At intervals of 0 to 0.1 seconds and 0.6 to 0.8 seconds, the octagon connection was separated at the maximum screw head displacement and the internal part of the abutment, but the morse taper connection did not exhibit any separation. In the above time intervals, the results were similar to the maximum state in case of the minimum displacement of the screw head and the internal part of the abutment.

Screw loosening is less likely to occur in the morse hex connection compared to the octagon connection due to the lack of separation of the screw from the internal surface of the abutment.

Local anesthesia is given to decrease pain perception during dental treatments, but it may itself be a reason for pain and aggravate the dental fear. Computer-controlled local anesthetic delivery system (CCLADS) is one of the alternatives for decreasing the patients’ pain during local anesthesia. This study compared the time required for the recovery from anesthesia, pain/discomfort during injection and pain/discomfort 24 hours after administering local anesthesia with CCLADS, a standard self-aspirating syringe and a conventional disposable 2-mL syringe.

The study was conducted on 90 subjects (an age group of 20-40 years), who suffered from sensitivity during cavity preparation. They were randomly divided into three groups of 30 individuals each to receive intraligamentary anesthesia (2% lignocaine with 1:80,000 adrenaline) using either of the three techniques: CCLADS, a standard self-aspirating syringe, or a conventional disposable 2-mL syringe. The onset of anesthesia, time required for recovery from anesthesia (in minutes), pain/discomfort during injection and pain/discomfort 24 hours after administering local anesthesia were recorded.

The time required for the onset of anesthesia and recovery from anesthesia was shorter with CCLADS (4.83±2.31 and 34.2±1.895, respectively) as compared to the standard self-aspirating group (10.83±1.90 and 43.5±7.581, respectively) and the conventional group (11.00±2.03 and 43.5±6.453, respectively) (P<0.001). The patients in the CCLADS group experienced no pain during local anesthesia administration as compared to the patients in the self-aspirating and conventional groups. The CCLADS and self-aspirating groups showed lower pain response as compared to the conventional group for pain after 24 hours.

CCLADS can be an effective and pain-free alternative to conventional local anesthetic procedures.

This in vitro study aimed to evaluate the microshear bond strength (μSBS), microhardness and morphological characteristics of primary enamel after treating with sodium fluoride (NaF) and acidulated phosphate fluoride (APF).

Forty-eight primary canines were cut into mesial and distal sections and assigned to five groups randomly: group 1 (immersed in saliva as a control), group 2 (treated with NAF and immersed in saliva for 30 minutes), group 3 (treated with APF and immersed in saliva for 30 minutes), group 4 (treated with NAF and immersed in saliva for 10 days), and group 5 (treated with APF and immersed in saliva for 10 days). Composite resin (Filtek Z250) was bonded on the specimens (n=15) for measuring the μSBS. After storage in 37°C artificial saliva for 24 hours, µSBS and Vickers hardness tests (10 readings) were performed. The data were analyzed using one-way ANOVA and Kolmogorov-Smirnov, Levene’s and Tukey HSD tests (P<0.05). Morphological analysis of enamel and modes of failure were carried out under a scanning electron microscope (SEM) on two remaining specimens.

Significant differences in μSBS were only noted between groups 2 and 4 (P=0.024). Group 3 showed a significant decrease in hardness after storage in artificial saliva (P<0.001), with a significantly lower hardness than the other groups (P<0.001). The SEM observations showed irregular particles in groups 3 and 5; uniform, smooth and thin coats were seen in groups 2 and 4.

Fluoride therapy with NaF and APF gels prior to restorative treatments had no adverse effects on the microshear bond strength.

The surgery-first approach (SFA), which proceeds without presurgical orthodontic treatment, is assumed to shorten the treatment course because the direction of post-surgical orthodontic tooth movement conforms to the normal muscular forces. Moreover, the regional acceleratory phenomenon (RAP), evoked by surgery, helps in tooth alignment and compensation in a faster way. Although SFA has definite advantages, especially in class III individuals, there is a lack of data about its indications in patients with facial asymmetry. In this article, we reviewed recently published articles on the treatment of asymmetric patients using the SFA. Different aspects, including the three-dimensional assessment of stability in different planes, approaches for fabrication of a surgical splint, predictability of the results, skills needed for bimaxillary surgery, indications as the treatment of choice for condylar hyperplasia, and combination with distraction osteogenesis in candidates with severe asymmetries were found to be the main topics discussed for patients presenting with facial asymmetry.

It is difficult to achieve successful pulpal anesthesia in mandibular posterior teeth with symptomatic irreversible pulpitis. The present study aimed to compare the effect of articaine/epinephrine anesthesia with articaine/epinephrine at a combination of 0.5 mol/mL of mannitol for the inferior alveolar nerve block (IANB) in patients presenting with symptomatic irreversible pulpitis in the mandibular first molar tooth.

One hundred patients with symptomatic irreversible pulpitis in the mandibular first molar tooth were selected and randomly divided into two groups based on the injection method. The first group underwent an IANB technique with 1.8 mL of articaine, whereas the second group received 2.9 mL of a formulation, consisting of 1.8 mL of articaine plus 1.1 mL of 0.5 mol/L of mannitol. Fifteen minutes after injections and anesthesia of the lip, the access cavity was prepared. According to the visual analog scale (VAS) criteria, no pain or mild pain for caries removal, pulp exposure and canal instrumentation were regarded as success. Chi-squared test was used for the analysis of data. The level of significance was set at 0.05.

The success rate in the group with articaine/epinephrine anesthesia plus mannitol was higher than that in the group with articaine/epinephrine anesthesia, with no significant difference between the two groups (P>0.05).

It was concluded, under the limitations of this study, that adding mannitol to articaine/epinephrine anesthesia did not increase the success of IANB in mandibular posterior teeth with symptomatic irreversible pulpitis.