Frontiers in Dentistry
Volume:12 Issue: 7, Jul 2015

Cleaning and shaping of the root canal system is an important step in endodontic therapy. New instruments incorporate new preparation techniques that can improve the efficacy of cleaning and shaping. The aim of this study was to compare the efficacy of Mtwo and RaCe rotary file systems in straightening the canal curvature using only one file or the conventional method. Sixty mesial roots of extracted human mandibular molars were prepared by RaCe and Mtwo nickel-titanium (NiTi) rotary files using the conventional and only one rotary file methods. The working length was 18 mm and the curvatures of the root canals were between 15-45°. By superimposing x-ray images before and after the instrumentation, deviation of the canals was assessed using Adobe Photoshop CS3 software. Preparation time was recorded. Data were analyzed using three-way ANOVA and Tukey’s post hoc test. There were no significant differences between RaCe and Mtwo or between the two root canal preparation methods in root canal deviation in buccolingual and mesiodistal radiographs (P>0.05). Changes of root canal curvature in >35° subgroups were significantly more than in other subgroups with smaller canal curvatures. Preparation time was shorter in one file only technique. According to the results, the two rotary systems and the two root canal preparation methods had equal efficacy in straightening the canals; but the preparation time was shorter in one file only group.

The aim of this study was to assess and compare the water sorption and flexural strength of thermoplastic and conventional acrylic resins. Water sorption and flexural strength were compared between a thermoplastic modified polymethyl methacrylate (PMMA) denture base resin (group A) and a heat-polymerized PMMA acrylic resin (group B) as the control group (n=10). A threepoint bending test was carried out for flexural strength testing. For water sorption test, 10 disc-shaped samples were prepared. After desiccating, the samples were weighed and immersed in distilled water for seven days. Then, they were weighed again, and desiccated for the second and third times. Differences between the mean values in the two groups were analyzed using Student''s t-test. The mean value of water sorption was 14.74±1.36 μg/mm3 in group A, and 19.11±0.90 μg/mm3 in group B; this difference was statistically significant (P< 0.001). The mean value of flexural strength was 88.21±8.63 MPa in group A and 77.77±9.49 MPa in group B. A significant difference was observed between the two groups (P= 0.019). Flexural strength of group A was significantly higher than that of group B, and its water sorption was significantly lower. Thus, thermoplastic resins can be a suitable alternative to conventional PMMA acrylic resins as denture base materials.

This study aimed to assess the radicular wall thickness in mandibular incisors with two canals and find the maximum and minimum thickness to prevent root canal treatment (RCT) procedural errors. A total of 160 extracted mandibular incisors were selected and radiographed; out of which, 55 had two canals. Three parallel transverse sections were made in each tooth at 1mm below the cementoenamel junction (CEJ), mid-root and 1 millimeter to the apex. Specimens were evaluated under a stereomicroscope and the thickness of radicular walls in each section was determined for the buccal, lingual and proximal surfaces. Data were statistically analyzed using Pearson’s correlation coefficient test. The thickness of radicular wall decreased from the cervical towards the apex. In all three sections (cervical, mid-root and apical), the thickness of lingual wall was significantly greater than the buccal wall. Also, the thickness of buccal and lingual walls was significantly higher than that of the proximal walls. The lingual radicular wall had the highest thickness in two-canal mandibular incisors. Therefore, in these teeth, the lingual canal is a better choice for post placement.

This study aimed to find the factors that affect dental esthetics and smile attractiveness in orthodontically treated patients according to laypeople’s judgment, and to determine whether there is any relationship between dental and smile esthetics. Using the Q-sort technique, 60 laypersons (30 males, 30 females) rated dental and smile photographs of 48 orthodontically treated patients based on their degree of attractiveness. Dental and smile parameters of each rated image were measured by Smile Analyzer software. The Student’s t-test and chi-square test were used to compare dental and smile parameters between attractive and unattractive images. The logistic regression was used to assess which variables predicted dental and smile esthetics in treated individuals. The philtral to commissural height ratio and gingival display were significantly different in attractive and unattractive smiles (P=0.003 and P=0.02, respectively). None of the dental variables were found to be a determinant of dental esthetics at the end of the orthodontic treatment (P>0.05). According to the judgment of all raters (female and male) and the male raters’ judgment, smile attractiveness could be predicted by philtral to commissural height ratio and buccal corridor ratio (P<0.05). There was no statistically significant relationship between dental esthetics and smile attractiveness in orthodontically treated patients (P>0.05). The philtral to commissural height ratio and buccal corridor ratio can be considered as predictors of smile attractiveness in orthodontically treated patients. Achieving dental esthetics at the end of orthodontic treatment does not guarantee smile attractiveness.

Platelet preparations are commonly used to enhance bone and soft tissue regeneration. Considering the existing controversies on the efficacy of platelet products for tissue regeneration, more in vitro studies are required. The aim of the present study was to compare the in vitro effects of plasma rich in growth factors (PRGF) and platelet-rich fibrin (PRF) on proliferation and viability of human gingival fibroblasts (HGFs). Anitua''s PRGF and Choukran''s PRF were prepared according to the standard protocols. After culture periods of 24, 48 and 72 hours, proliferation of HGFs was evaluated by the methyl thiazol tetrazolium assay. Statistical analysis was performed using one-way ANOVA followed by Tukey-Kramer’s multiple comparisons and Pvalues<0.05 were considered statistically significant. PRGF treatment induced statistically significant (P<0.001) proliferation of HGF cells compared to the negative control (100% viability) at 24, 48 and 72 hours in values of 123%±2.25%, 102%±2.8% and 101%±3.92%, respectively. The PRF membrane treatment of HGF cells had a statistically significant effect on cell proliferation (21%±1.73%, P<0.001) at 24 hours compared to the negative control. However, at 48 and 72 hours after treatment, PRF had a negative effect on HGF cell proliferation and caused 38% and 60% decrease in viability and proliferation compared to the negative control, respectively. The HGF cell proliferation was significantly higher in PRGF than in PRF group (P< 0.001). This study demonstrated that PRGF had a strong stimulatory effect on HGF cell viability and proliferation compared to PRF.

Bone assessment is essential for diagnosis, treatment planning and prediction of prognosis of periodontal diseases. However, two-dimensional radiographic techniques have multiple limitations, mainly addressed by the introduction of three-dimensional imaging techniques such as cone beam computed tomography (CBCT). This study aimed to assess the accuracy of CBCT for detection of marginal bone loss in patients receiving dental implants. A study of diagnostic test accuracy was designed and 38 teeth from candidates for dental implant treatment were selected. On CBCT scans, the amount of bone resorption in the buccal, lingual/palatal, mesial and distal surfaces was determined by measuring the distance from the cementoenamel junction to the alveolar crest (normal group: 0-1.5mm, mild bone loss: 1.6-3mm, moderate bone loss: 3.1-4.5mm and severe bone loss: >4.5mm). During the surgical phase, bone loss was measured at the same sites using a periodontal probe. The values were then compared by McNemar’s test. In the buccal, lingual/palatal, mesial and distal surfaces, no significant difference was observed between the values obtained using CBCT and the surgical method. The correlation between CBCT and surgical method was mainly based on the estimation of the degree of bone resorption. CBCT was capable of showing various levels of resorption in all surfaces with high sensitivity, specificity, positive predictive value and negative predictive value compared to the surgical method. CBCT enables accurate measurement of bone loss comparable to surgical exploration and can be used for diagnosis of bone defects in periodontal diseases in clinical settings.

This study was undertaken to evaluate the viability of periodontal ligament (PDL) cells of avulsed teeth in three different storage media. Forty-five premolars extracted for orthodontic therapeutic purposes were randomly and equally divided into three groups based on storage media used [Group I: milk (control); Group II: aloe vera (experimental); Group III: egg white (experimental)]. Following extractions, the teeth were placed in one of the three different storage media for 30 minutes, following which the scrapings of the PDL from these teeth were collected in Falcon tubes containing collagenase enzyme in 2.5 mL of phosphate buffered saline. The tubes were subsequently incubated for 30 minutes and centrifuged for five minutes at 800 rpm. The obtained PDL cells were stained with Trypan Blue and were observed under optical microscope. The percentage of viable cells was calculated. Aloe vera showed the highest percentage of viable cells (114.3±8.0), followed by egg white (100.9±6.3) and milk (101.1±7.3). Within the limitations of this study, it appears that aloe vera maintains PDL cell viability better than egg white or milk.

During endodontic treatment, clinicians may face endodontic procedural mishaps such as broken instruments, which is a complex situation especially when the file breaks beyond the apex. This condition is associated with potential risk of contamination, which compromises the healing process. Management of a broken instrument beyond the apex is difficult and time consuming and requires creativity as well as clinical knowledge and skills. Several devices and techniques have been developed to retrieve the fractured instruments, but none are consistently successful. This case report describes a technique using modern ultrasonic tips for retrieval of broken instruments separated beyond the apex.

Palisaded encapsulated (solitary circumscribed) neuromas (PENs) are relatively common intraoral neurogenic tumors, which occur most frequently on the hard palate. Herein, we describe the clinicopathological characteristics of a palisaded encapsulated neuroma of the tongue. This tumor was an exophytic sessile mass measuring 0.3× 0.4 cm with rubbery consistency on the anterior one-third of the dorsum of the tongue. The tumor was excised under the impression of a pyogenic granuloma (PG). No recurrence was reported at 12 months postoperatively. Histopathological examination showed a well-circumscribed mass that composed of interlacing fascicles of spindle cells. The cells were S-100 positive. The nuclei, showing parallel orientation within the fascicles, were wavy and pointed and showed no sign of mitotic activity. Giemsa staining revealed no mast cells within the stroma.

The maxillofacial region is one of the most injury-prone areas during road traffic accidents, personal violence, falls and sports. Maxillofacial trauma can lead to breakage or avulsion of upper anterior teeth, which may cause significant aesthetic and functional problems. There are many treatment options available for rehabilitation including removable partial dentures, fixed partial dentures, crown and bridges and implantsupported prostheses. Herein, two cases are presented where implant placement was done for upper anterior teeth, which were traumatized or avulsed following maxillofacial trauma. Both patients demonstrated a history of maxillofacial trauma and had undergone open reduction and internal fixation. The first patient had a severe maxillary alveolar defect treated via autogenous bone grafting and a six-month period was given for proper integration of the bone graft. The second patient was a smoker with very poor oral hygiene and a deep bite. Thus, implant placement was not initially justified.