Journal of Research in Dental and Maxillofacial Sciences
Volume:5 Issue: 4, Autumn 2020

High chipping rates of the veneering porcelain of zirconia ceramic restorations have been reported in clinical studies. Thus, the shear bond strength (SBS) between the zirconia core and veneering porcelain requires investigation.

In this in-vitro study, at first, using a computer-aided design/computer-aided manufacturing (CAD/CAM) machine, 16 zirconia cores of Kerox were provided. Using the casting method, 16 base metal cores were provided. All the cores were veneered with the Creation ceramic veneer. Afterwards, the samples were put under a static force in the universal testing machine at a crosshead speed of 1 mm/minute until fracture. T-test was used to analyze the data.

The mean SBS for the base metal and zirconia groups was 27±7.43 and 27.75±8.75 Megapascal (MPa), respectively (P=0.812).

There was no significant difference between the metal-ceramic and zirconia ceramic groups in SBS so that the Creation ceramic veneer may solve the problems related to the bond of all-ceramics to ceramic veneers.

Preparation of root canal with rotary nickel-titanium (NiTi) instruments may potentially create microcracks that can lead to vertical root fracture. This study aimed to compare the incidence of crack formation by BioRaCe and Edge Taper Platinum systems in the mesiobuccal canals of extracted first mandibular molars.

In this experimental study, 50 first mandibular molars, which met all the inclusion criteria, with a canal curve of 25-35 degrees, were selected and randomly divided into two groups of 24. Each specimen was mounted in a resin block and a thin layer of silicone impression to simulate the periodontal ligament (PDL) while the apex was exposed. Group A was prepared by BioRaCe, and group B was prepared by Edge Taper Platinum. Two teeth were left unprepared and served as the control. The roots were sectioned horizontally at 3, 6, and 9mm from the apex and evaluated under a stereomicroscope at ×20 magnification. The presence of dentinal defects was examined and analyzed using Mann-Whitney test.

BioRaCe rotary files showed more cracks (47.3%) than Edge Taper Platinum (19.5%) at all three levels with a significant difference (P=0.038). No statistically significant difference was found between these two systems at the coronal (9mm from the apex) and apical (3mm from the apex) levels but a significant difference was found between BioRaCe and Edge Taper Platinum in the midroot (6mm from the apex; P=0.014).

It seems that the Edge Taper Platinum system causes fewer cracks in curved dentinal walls compared to the BioRaCe system.

Research on reducing the symptoms and discomfort after periodontal surgery is a priority. This study aimed to evaluate the effect of cyanoacrylate adhesive on tissue healing after periodontal surgery.

In this split-mouth clinical trial, all patients who needed periodontal pocket removal surgery in two or more sextants were examined after receiving written informed consent. The mouth of each patient was randomly divided into control and case groups. Cyanoacrylate adhesive was used in the case group, and sutures were used in the control group to close the wound. Pain, plaque index of the surgical site, and tissue healing were evaluated in the first week of follow-up. The probing depth in the surgical site was assessed at the second follow-up (6 weeks after surgery). All the parameters were statistically analyzed by Mann-U-Whitney test.

In the first week of follow-up, the level of pain was 4.7±1.34 in the control group and 4.4±1.68 in the case group with no statistically significant difference (P=0.2). The healing rate was 3.3±0.53 in the control group and 2.7±0.64 in the case group with no statistically significant difference (P=0.3). The plaque index in the first week of follow-up was 3.9±0.82 in the control group and 3.8±0.97 in the case group (P=0.2). The probing depth in the sixth week of follow-up was 2.5±0.67 in the control group and 2.8±0.6 in the case group (P=0.2).

Considering the results, it seems that cyanoacrylate adhesive can be a good alternative to sutures, especially when the patient cannot present for suture removal at the appointed time.

The hardness and wear resistance of denture teeth have great importance in the longevity of dentures. This study assessed the effect of 0.2% chlorhexidine (CHX) and alcohol-free Listerine on the microhardness of acrylic denture teeth.

In this in-vitro experimental study, 26 Major Plus teeth were randomly divided into three groups for immersion in 0.2% CHX, alcohol-free Listerine, and distilled water. Two teeth were not immersed in mouthwash to assess baseline microhardness. The teeth were mounted in wax blocks (20×20×6 mm), which underwent wax burnout and were replaced with heat-cure acrylic resin. The samples were immersed in the solutions for 120 minutes corresponding to 4 months of clinical service. They were removed from the solutions twice daily, each time for 30 seconds, rinsed with distilled water, and placed again in the solutions. Next, they were stored at room temperature for 24 hours. They were thermocycled and subjected to microhardness measurement at the incisal third of their labial surface using the Vickers test. Data were analyzed using t-test.

The baseline microhardness (n=2) was 27.9±0.98. The microhardness of samples immersed in CHX was 12 units (36.8%) lower than that of samples immersed in distilled water; this difference was statistically significant (P<0.002). The microhardness of samples in Listerine was 7.4 units (29.4%) lower than that of samples in distilled water with no statistically significant difference (P=0.1).

Immersion of acrylic teeth in 0.2% CHX can significantly decrease their microhardness. The effect of non-alcoholic Listerine on microhardness is similar to that of distilled water.

The selection of an appropriate imaging or diagnostic technique is an important therapeutic step, which protects patients from the harmful effects of radiation. This study aimed to evaluate the knowledge and attitude of dentists and dental students towards cone-beam computed tomography (CBCT).

This analytical-descriptive study evaluated a closed-ended questionnaire consisting of 16 questions, which was given to 100 participants, including faculty members, postgraduate students, and interns of our institution. Their response was analyzed by chi-square test.

In total, 100 questionnaires were analyzed. The mean age of the study population was 31.43±18 years (range: 23-45 years). Approximately 94% of the participants knew that the radiation dosage of CBCT is lower than that of CT. They obtained knowledge about CBCT through the committed dose equivalent (CDE), journals, seminars, internet, etc. Approximately 40% of the participants preferred CBCT scans for implant placement, 24% for trauma, 22% for cysts and tumors, and 14% for root canal treatment. About 54% of the participants considered CBCT as a part of the oral medicine and radiology domain and considered it necessary in oral and maxillofacial radiology departments only.

This study showed that the participants had the knowledge and a positive attitude towards the regular use of CBCT for various clinical applications. This study also suggests that CBCT training of dental students helps all dentists to improve the precision and reliability of oral and maxillofacial-related diagnosis, treatment planning, and prognosis by effectual use of this technology.

Root canal preparation with systems with the least chance of dentin cracking can increase the success of endodontic treatment. This study aimed to compare the One-Shape and XP-endo Shaper rotary files in the dentin crack incidence in the mesiobuccal canals of mandibular first molars.

In this experimental study, 60 eligible extracted mandibular first molars were randomly divided into three groups. The roots were prepared to #30 and 4% taper in the XP-endo Shaper group and #25 and 6% taper in the One-Shape group. The control samples were left intact. All groups were sectioned at 2, 4, and 6mm from the apex and examined under a stereomicroscope at 20× magnification. The incidence, location, and type of cracks were analyzed using chi-square test.

There were no cracks in the controls. The crack percentage was 23.33% (n=14) and 11.66% (n=7) in the One-Shape and XP-endo Shaper groups, respectively, with a significant difference with crack-fee samples. There was no significant difference between One-Shape and XP-endo Shaper systems in the three sections (P>0.05). In the 2mm section, cracks were observed in six sections (10%) with One-Shape and four sections (20%) with XP-endo Shaper. In the 4mm section, cracks were observed in one section (5%) with One-Shape and five sections (25%) with XP-endo Shaper. In the 6mm section, cracks were observed in seven sections (35%) with One-Shape and one section (5%) with XP-endo Shaper.

The One-Shape and XP-endo Shaper systems were similar in crack incidence in the mesiobuccal canal of mandibular first molars.

The calcifying odontogenic cyst (COC) is a rare cystic lesion, mainly affecting the anterior aspect of the jaws. It is usually discovered in unexpected settings and can be clinically observed as a painless and well-defined lesion. The COC may be associated with other odontogenic tumors, such as odontomas. Nearly 50% of COCs are associated with an unerupted tooth, most often a canine. The most unique features of this pathology are histopathological features, including a cystic lining with characteristic ghost epithelial cells with a tendency for calcification. Radiological examinations often reveal a radiolucent and unilocular lesion, sometimes associated with radiopaque lesions. Pathological assessments are required for the final diagnosis. Management is through complete excision with annual radiographic monitoring for five years.

Here, we report a classic case of COC in the left mandibular region associated with an extremely displaced impacted canine in a 16-year-old girl.

Although uncommon, COCs are frequently associated with impacted teeth. The radiolucencies associated with impacted teeth have different effects on the surrounding structures and require different treatment plans, depending on the type of the lesion.