Effect of Surface Treatment With Er:YAG and CO2 Lasers on Shear Bond Strength of Polyether Ether Ketone to Composite Resin Veneers.

Introduction: Polyether ether ketone (PEEK) has low surface energy and high resistance to chemical surface treatments. Therefore, different surface treatments such as laser conditioning should be investigated. There is a gap of information regarding the efficacy of laser irradiation in the surface treatment of PEEK, and the efficacy of several laser types needs to be evaluated for this purpose. This study aimed to assess the effect of surface treatment with erbium-doped yttrium aluminum garnet (Er:YAG) and carbon dioxide (CO2) lasers on shear bond strength (SBS) of PEEK to composite resin veneers. Methods: In this experimental study, 60 rectangular-shaped PEEK samples (7 x 7 x 2 mm) were used. The samples were mounted in auto-polymerizing acrylic resin in such a way that only one surface measuring 7x7 mm remained exposed. The samples were then randomly divided into 3 groups (n=20) of control, Er:YAG laser surface treatment (Power=1.5 W, energy density=119.42 J/cm2 , irradiation time=20 s) and CO2 laser surface treatment (Power=4 W, energy density=159.22 J/cm2 , irradiation time=50 s). The bonding agent and PEEK opaque were applied on the surface of samples and they were veneered with a composite resin using a hollow plastic cylinder with an internal diameter of 4 mm. The SBS was then measured and the data were analyzed using one-way ANOVA, Tukey HSD test and Dunnett's test at 0.05 level of significance. Results: The SBS of the 3 groups was significantly different (P<0.001). The Tukey HSD test revealed that the Er:YAG laser had higher SBS than the CO2 laser group (P<0.001). The Dunnett's test showed that both Er:YAG and CO2 laser groups yielded higher SBS than the control group (P<0.001). Conclusion: The Er:YAG and CO2 laser treatments can increase the SBS of PEEK to composite resin veneers, although the Er:YAG laser seems to be more effective for this purpose.

Accuracy of Implant Abutment Level Impression with and without Impression Coping.

AIM: Transferring an accurate copy of the patient's soft and hard tissue to the dental laboratory is of essential importance. Various methods of implant impression have different outcomes on dimensions of final cast. This study aimed to compare two methods of implant impression on abutment level with and without impression coping on two parallel implants. MATERIALS AND METHODS: In this experimental study, a resin model with two holes for fixing the implant was made. The first and second implants had a 4 and 11 mm distance to canine respectively. In this study two methods were used for impression: first was direct (without impression coping) and second was indirect (with the impression coping). Ten impressions were prepared for a total of 10 stone casts. For analyzing the abutment analogs positions, each cast was analyzed using a cruicial malformation and malarticulatoin (CMM) in three dimensions (X, Y, and Z). The difference in dimensions of final casts and laboratory models were analyzed using Independent t-test. RESULTS: The results did not show a significant difference between direct and indirect methods in Z and Y axis in absolute transmission (Δr). The dimensional changes in the X-axis in the direct method was 0.647 ± 0.155 which is 0.067 ± 0.146 more than the indirect method. A significant difference (p = 0.044) was observed between the two methods in X-axis. CONCLUSION: Based on the results, this research found the indirect impression on abutment surface to be more accurate than the direct one. In general, two methods were not significantly different, and dentists can use the simple method of the direct impression for making implant prosthetics. CLINICAL SIGNIFICANCE: Reconstruction of implant's accurate position in the process of impression, along with a tension-free insertion, is the first step in having an accurate prosthesis. Abutment level impression with the impression coping is slightly more accurate than the one without impression coping.

Clinical Evaluation of Effects of Local Application of Aloe vera Gel as an Adjunct to Scaling and Root Planning in Patients with Chronic Periodontitis.

STATEMENT OF THE PROBLEM: Aloe vera gel contains various components with antibiotic and anti-inflammatory characteristics, which may have potential advantages to treat periodontal diseases. PURPOSE: The aim of this study was to evaluate the effects of local application of aloe vera gel as an adjunct to scaling and root planning in the treatment of patients with chronic periodontitis. MATERIALS AND METHOD: This single-blind clinical trial, performed in a split mouth design, was conducted on 20 patients with moderate to severe chronic periodontitis. Following a baseline examination at first day which included the assessments of plaque index (PI), gingival index (GI), and probing depth (PD); patients randomly received either SRP in one quadrant (control group), or SRP combined with aloe vera gel in another quadrant (experimental group). All cases were examined again, assessing PI, GI, and PD at 30th and 60th day. RESULTS: There was no significant difference in PI in the three stages between control and experimental groups. In all patients, there was a significant improvement in the three stages in GI and PD for both quadrants treated only with SRP or combination of SRP and aloe vera. However, experimental group presented significantly lower GI (p= 0.0001) and PD (p= 0.009) than the control group at the end of study period. CONCLUSION: This study revealed that local application of aloe vera gel could be considered as an adjunctive treatment with scaling and root planning for chronic periodontitis.

Designing and assessing fixed dental prostheses 2 multimedia-based education in dentistry students.

Background: Above all methods effective learning results from decent training, acquired in the proper environment and encouraging creative methods. Computer-assisted training by educational software is considered a fundamental measure to improve medical and dentistry education systems. This study aims to design and assess fixed dental prostheses via 2 multimedia instructional contents at the Guilan dentistry school. Methods: This is a descriptive and cross-sectional study. First off, the instructional content was analyzed. The software used to produce multimedia was the iSpring suite Ver.7.0. After designing the instructional multimedia, this software was loaded by LMS. Sixty-nine dentistry students in the 5th semester at Guilan Dentistry School were selected via convenience sampling. At the end of the course, a structured questionnaire containing 26 items were handed to the students to evaluate the instructional multimedia quality. Results: Mean ±SD age was 24.68±3.24 years, 43 were women (62.4%) and 26 were men (37.6%) -the majority of 76.8% used the internet at home. A portion of 33.3% were inclined to use multimedia and the internet with in-person training. About 60% declared that multimedia quality as being good. Conclusion: the instructional multimedia designs which are compatible with lesson objectives and audiovisual facilities can have a great effect on the student's satisfaction. Preparing instructional multimedia makes the instructional content easily accessible for students to be able to review it several times at the proper opportunity and if presented through LMS they would be able to study the lesson subject wherever and whenever accessing the internet.