Caspian Journal of Dental Research
Volume:11 Issue: 2, Sep 2022

Metal brackets are the most commonly used brackets in clinical orthodontics, but the sight of color of the metal bracket can be unpleasant for some patients. Ceramic brackets offer the desired beauty but they have higher frictional resistance.  Considering that in vitro studies suggest that CO2 laser reduces the friction between the wire and slot of the bracket in the sliding mechanics, the aim of this study was to evaluate the clinical effect of CO2 laser on the speed of tooth movement using the sliding mechanics.

This randomized double-blind clinical trial was performed on 7 patients and a total of 13 half jaws in each group. These patients were candidates for bilateral extraction of the first premolars due to lack of space or dentoalveolar protrusion. After alignment and leveling, the ceramic brackets were passively bonded. The ceramic brackets of the experimental group irradiated with the CO2 laser and the brackets of the control group were bonded unchanged. The brackets were examined with an atomic force microscope (AFM) before and after irradiation. Statistical data were analyzed paired t-test to compare the rate of gap closure between the two groups at one-month intervals. ANOVA was used to examine the reduction in spacing at three-month intervals. A value of p<0.05 was considered statistically significant.

The rate of gap closure between the two groups was compared at one-month intervals, which was not statistically significant in either month. Furthermore, in the comparison between the study and control groups, the decrease in the distance between the canine and second premolars was not statistically significant after a total of three months (p=0.0918).

According to the results of this study, CO2 laser irradiation of the bracket surface has no effect on the speed of movement of the canine when sliding on the wire.

Etching the internal surface of ceramic restorations with hydrofluoric (HF) acid and silane is a well-accepted technique to enhance the bond strength. The aim of this study was to assess the effect of concentration of hydrofluoric acid and etching time on microtensile bond strength (µTBS) of zirconia-reinforced lithium silicate (ZLS) ceramics in 2021.

This in vitro study was conducted on 8 Celtra-Duo ceramic blocks size 14 measuring 12×14×18 mm. Each ceramic block was divided into three equal pieces by a cutting machine to obtain a total of 24 specimens. The specimens were randomly divided into 6 groups for etching with 5% and 10% HF acid for 30, 60, and120 seconds. Silane (Clearfil porcelain activator) and bonding agent (Clearfil SE Bond) were applied to the etched specimens. Panavia F2 resin cement was applied on the surfaces and light-cured. The mTBS of resin cement to porcelain was measured by a universal testing machine. The mode of failure was determined under a stereomicroscope at x40 magnification. Data were analyzed by one- and two-way ANOVA (P<0.05).

The mean mTBS of Celtra-Duo ceramics subjected to etching for 30, 60, and 120 seconds was not significantly different in the use of 5% and 10% HF acid concentrations (P>0.05). Two-way ANOVA showed that the effects of HF acid concentration and etching time, and their interaction effect were not significant on µTBS of CAD/CAM Celtra-Duo ceramics (P>0.05). The mode of failure was dominantly adhesive in both concentrations of 5% and 10% HF acid. No mixed failure occurred in both concentrations. 

Considering the non-significant difference in µTBS of ceramics subjected to different concentrations of HF acid for different times, the application of HF acid with lower concentration for a shorter period is recommended to prevent possible adverse effects on ceramic strength.

 The oral cavity has been suggested as a potential reservoir for Helicobacter pylori (H. pylori), which could be a major cause of reinfection after standard systemic therapy. The aim of this study was to evaluate the effect of full-mouth disinfection (FMD) on the recurrence of H. pylori infection.

This randomized clinical trial was conducted on 40 patients with chronic periodontitis and H. pylori infection. Of these, 20 patients received quadruple anti-H. pylori therapy only (group A) and the other 20 patients received quadruple therapy plus FMD (group B). The presence of H. pylori was detected by a 14C-urea breath test (UBT) after 1 and 6 months. Data were analyzed with SPSS 16 using the chi-square test. A value of p<0.05 was considered statistically significant.

Of 40 dyspeptic patients, 15(75%) and 18(90%) of 20 in groups A and B, respectively, had a negative UBT after 4 weeks. Of the patients with successful eradication of H. pylori after 1 month, 8(53.3%) and 6(33.3%) of 15 in group A and 18 in group B, respectively had a positive UBT after 6 months. There were no statistically significant differences between the two groups in the follow-up periods (p>0.05).

Implementation of quadruple therapy plus FMD may reduce recurrence of the infection although further studies are recommended to confirm the results.

Accurate duplication of casts is necessary to fabricate a proper prosthetic appliance with good adaptation. Alginate is an inexpensive impression material and is available in most dental offices. The aim of the present study was to evaluate the accuracy of the casts duplicated using alginate impression mold.

In this in vitro study, at first, a metallic tray and condensational silicone impression material were used to prepare 60 master impressions of a maxillary dental model. The impressions were poured using stone gypsum, and their dimensions were measured via a digital Vernier caliper with accuracy of 0.01 mm. Then, the casts were fixed on the floor of a flask filled with alginate with two folds volume of cold water recommended by the manufacturer. The resulting impressions were immediately poured, and the measurements were repeated. The data were analyzed with SPSS 26 using MANOVA and ICC index (p<0.05).

Statistical analyses showed that dimensional changes of the duplicated casts were not significant relative to the master casts (P=0.90). In addition, insignificantly, the duplicate casts were smaller than the master casts and the dimensional changes in the transverse dimension were more than those in the anteroposterior dimension.  

The results indicated that alginate duplicate impressions taken using the alginate molding technique had good dimensional accuracy when they were poured immediately. Since alginate is inexpensive, this technique can be used in the dental office by saving time to decrease laboratory costs and avoid using expensive impression materials.

Oral lichen planus (OLP) is a chronic mucocutaneous inflammatory disorder with an unknown etiology. Although a considerable body of evidence suggests that immunologic factors are involved in the etiology of OLP, the involvement of cytokines in the pathogenesis of the disease is not fully understood yet. The aim of the present study was to assess interleukin-6 (IL-6) levels as a proinflammatory cytokine in the saliva of OLP patients compared to healthy controls.

This case-control study was conducted on 30 OLP patients (12 males and 18 females)  and 30 healthy control subjects, selected from individuals who were referred to the Department of Oral and Maxillofacial Diseases in Faculty of Dentistry, Babol University of Medical Sciences. Samples of unstimulated saliva were collected. Salivary IL-6 levels were measured using an ELISA kit and compared between OLP patients and healthy controls. The collected data were analyzed by Chi-square, independent t-test, and receiver operating characteristic (ROC) curve using SPSS 18 Sensitivity, specificity, positive predictive values (PPVs), and negative predictive values (NPVs) ​​were calculated. A value of p<0.05 was considered significant.

Mean salivary IL-6 values in OLP patients and healthy controls were 24.68±9.90 ng/L and 13.76±9.27 ng/L, respectively. The difference was statistically significant (P<0.001). The mean IL-6 values in reticular and erosive forms of OLP clinically were 24.35±9.26 ng/L and 24.91±10.64 ng/L, respectively. This difference was not statistically significant (P=0.87).

Higher levels of IL-6 in saliva of OLP patients compared with healthy controls support the role of IL-6 in the pathogenesis of the disease.

One of the factors affecting the success of bonded restoration is the use of appropriate adhesives and attention to their maintenance time. The aim of this study was to investigate the effect of three time periods related to the expiration date of two universal adhesives on the bond strength of resin composite to dentin.

In this in-vitro study, 30 intact third human molars were selected. The roots of the teeth were cut and the crown part was mounted in acrylic resin in such a way that the enamel of the buccal surface was clearly visible. Using abrasive disks, the enamel of the buccal surface of the teeth was abraded to create a flat dentin area with dimensions of 25 mm2. The samples were randomly divided into 2 groups based on adhesive type (All Bond (Bisco, Fchaumburg,IL, USA) G-Permio  and each group was divided into 3 subgroups based on expiration date. After the bonding process and fabrication of composite samples, microtensile bond strength (TBS) was measured at a speed of 1 mm/min. The data were analyzed using the Kruskal-Wallis test and post hoc Tukey's test. P<0.05 was considered as significant level.

Significant differences were found among samples with different expiration dates in both All-Bond Universal (p=0.0001) and G-Premio (p=0.0001) groups in terms of micro TBS (μTBS). In both adhesive groups, a significant difference was found between 2 months after expiration with expiration time and 2 months before expiration, but there was no significant difference between expiration time and 2 months before expiration.

 The end of the expiration date has a reducing effect on the μTBS of universal adhesives investigated in this study. However, the amount of this effect varies depending on the type of adhesive.

 Recently, a new category of dental bonding agents called universal adhesives has been introduced to the market, which are claimed to be able to create a strong bond between composite resins and teeth, metal surfaces and all types of ceramics alone and without the use of other primers. The aim of this study was to evaluate the performance of universal adhesives in the repair of amalgam restorations with composite resins in comparison with the conventional method.

 In this experimental in vitro study, 80 amalgam blocks were prepared and after abrading the surface with an intraoral sandblaster and performing the aging process, the specimens were divided into 4 groups of 20 each, depending on how each surface was prepared by different bonding in the following order: Single Bond2 (S), Alloy Primer and Single Bond (AS), G-Premio Bond (G) and Alloy Primer and G-Premio Bond (AG). The composite blocks were then cured on the surface of the specimens. Finally, the specimens were tested for micro-shear bond strength (µSBS) using a micro-tensile tester and their cross-section was examined for fracture pattern under a stereomicroscope. Data were analyzed using Kruskal-Wallis, Man Whitney, and chi-square tests. A value of P<0.05 was considered significant.

 The highest and lowest bond strengths belonged to the AG and S groups, respectively. The mean difference of µSBS in the four groups was significant, except in the AS and G groups.

 G-Premio universal bond is able to create sufficient bond strength between composite and amalgam. However, it is recommended to use a combination of Alloy Primer with all bonding systems to improve bond strength.

 Adequate knowledge of dental anatomy is essential for successful endodontic treatment. The aim of this study was to determine the frequency of radix molaris in permanent mandibular first and second molars using cone-beam computed tomography (CBCT) in Rafsanjan-Iran in 2020.

 The present study was conducted on CBCT images taken at a private oral and maxillofacial radiology clinic in Rafsanjan, Iran, in 2020. A total of 407 teeth were examined. An experienced radiologist reconstructed and examined the images in axial and, if necessary, sagittal section. Finally, the data were entered into SPSS 22 and analyzed using the chi-square test. A value of P<0.05 was considered statistically significant.

 A total of 365(89.8) teeth, including 156 first molars and 209 second molars, were included in the study. Of these, 212 (58.1%) belonged to females and 153 (41.9%) to males. Sixteen (4.4%) teeth had three roots, all of which were first molars. Moreover, the extra roots were on the distolingual side and were radix entomolaris in all 16 cases. The prevalence of radix molaris was significantly higher in first molars (P=0.001) but did not differ by tooth side or sex.

 The three-rooted mandibular first molars may occur in the Iranian population and are not a rare phenomenon.

Peripheral ameloblastoma (PA) is a rare subtype of ameloblastoma that occurs in soft tissue. It most commonly affects the mandible and is more common in males. It most commonly occurs in the sixth decade of life. This case report represented a 19-year-old girl with a 10-mm lesion on the lingual gingiva of the mandible. The surface was papillary and no pain or bleeding was noted. Histopathologic examination revealed neoplastic proliferation of odontogenic epithelial cells nested in a connective tissue context. Unlike many other PA cases, these nests appeared to originate from the basal cell layer of the epithelium. Cone-beam computed tomography and orthopantomogram did not reveal severe bone involvement and aggression. The patient is planned to be followed-up for 10 years. The prognosis of patients with PA is generally good, but cases of lesion recurrence have been reported. Due to the rarity of PA, further studies are needed on its development and treatment outcome.