Effects of Desensitizers, Temporary Cements, and Dentin Cleaning Methods on the Bond Strength of Self-Etch/ Adhesive Resin Cements to Dentin: An In Vitro Study

Aim: The aim of this study was to evaluate the effect of desensitizer, temporary cements, dentin cleaning methods on shear bond strength (SBS) of self-etch and self-adhesive resin cements to dentin. Materials and Methods: Four hundred eighty buccal or lingual/palatine coronal portions of human molar teeth were mounted in the acrylic blocks. Teeth surfaces were prepared until the dentin was exposed. Specimens were divided into four groups. One group separated as control and three groups of teeth were treated with a desensitizing agent containing calcium-phosphate desensitizer (Teethmate Desensitizer, TMD), resin-based self-reinforcing monomer (Shield Force Plus, SFP) and 2-hydroxyethyl methacrylate and glutaraldehyde (Gluma Desensitizer). Two different temporary cement containing calcium hydroxide (Dycall) and zinc oxide based (Rely X Temp NE) temporary cement were applied to the dentin surfaces. Temporary cement was removed with one of three cleansing techniques: 2% chlorhexidine digluconate and glass particles containing agent (Consepsis Scrub), cleansing bur (OptiClean), and ıntra/extracoronal rotary brush (Starbrush). All groups were further divided into two cementation subgroups (Panavia V5 and Panavia SA). The SBS (MPa) was measured using a universal testing machine at 0.5 mm/min crosshead speed. The data were analyzed statistically with a four-way analysis of variance and Tukey’s Honest Significant Difference test ( α = 0.05). Results: Although SFP showed higher SBS, there was no statistically significant difference between other groups ( P > .05). There were no significant differences between temporary cements ( P > .05). OptiClean rotary bur showed higher mean SBS values in all groups. The dual-polymerized Panavia V5 showed the highest SBS values in all groups ( P <.05). Conclusion: Cleaning of dentin surface from temporary cement remnants with a silicon bur and dual-cure resin cement showed the highest bond strength values.

The Effect of Dentin Treated with Calcium Phosphate Desensitizer on Shear Bond Strength with Different Resin Cement: An In Vitro Study

Aim: The aim of this study was to evaluate the effect of calcium phosphate based desensitizing agent on shear bond strength of self-etch/adhesive resin cements to dentin. Materials and Methods: Eighty dentin specimens were prepared from freshly extracted human third molar teeth and were classified, randomly ( n = 20). Half of groups were treated with calcium phosphate based Teethmate Desensitizer and then Panavia V5, RelyX Ultimate (containing self-etch primer), Panavia SA, and RelyX U200 self-adhesive resin cements were luted to all dentin surfaces. All specimens were stored in an incubator at 37°C for 24 h. Shear bond strength was tested by a universal test machine at a 0.5 mm/min crosshead speed. The data were analyzed with a statistical program. Two-way ANOVA was used for statistical differences ( P <.05). Dentin surfaces were examined with scanning electron microscopy (SEM) at x5000 and x10000 magnifications. Results: The higher shear bond values were observed in the groups with Teethmate Desensitizer applied and cemented with self-etch (16.05 ± 6.24 and 14.73 ± 4.75), whereas the lowest bonding values were observed in the groups with self-adhesive resin cement without Teethmate Desensitizer (3.73 ± 0.77 and 5.85 ± 4.19; P <.001). As the main effect of the treatment, the bond strength was 9.39 ± 6.04 in the control group, whereas it was 13.49 ± 5.44 in the Teethmate applied groups ( P <.05) Conclusions: Calcium phosphate desensitizer did not adversely effected shear bond strength of self-etch/adhesive resin cements to dentin. It even significantly increased the shear bond strength of self-adhesive resin cements.

Identification of Dominant Bacteria Isolated From Periodontal Abscesses

Aim: Various methods investigating the bacterial content causing periodontal abscesses have been applied in studies conducted until today. However, these studies have focused on periodontopathogens. Our study was carried out to research whether different pathogens other than the known periodontopathogens are present in periodontal abscess formation. Therefore, dominant bacterial samples obtained from the periodontal abscess content using the culture-dependent method were identified by 16S rDNA sequencing. Materials and Methods: Samples were obtained using a syringe or a periopaper from periodontal abscesses of 20 volunteers who met the research criteria. The three different bacterial colonies that were observed most intensely in each sample were selected and purified, and the isolates obtained were kept until the next characterization. Genomic DNA was isolated from each isolate; 16S rRNA genes were amplified by polymerase chain reaction and identified using DNA sequencing analyses. Results: As a result of culture-dependent methods, bacterial species belonging to Streptococcus, Staphylococcus, Neisseria, Actinomyces, Morococcus, Moraxella, and Enterococcus genera were isolated from a total of 60 bacterial isolates, three of which were the most densely growing colonies from each periodontal abscess sample. Conclusion: In our study, most of the bacterial species detected were identified for the first time in the bacterial content of periodontal abscesses. In some previously done studies, most of these bacteria species were shown to cause abscesses in different parts of the body. It was concluded that further studies are needed to determine the number and proportion of these bacteria species in total bacterial content to evaluate whether they cause periodontal abscesses.

Evaluation of Color Changes of Different Resin Cements in Feldspathic Ceramic Crowns After Accelerated Aging: An In Vitro Research

Aims: To evaluate the color changes that occur after accelerated aging in feldspathic ceramic crowns cemented with three different dual-cured resin cements. Materials and Methods: For each of the A2-colored RelyX U200, G-CEM LinkForce, and Panavia V5 cement groups, 45 dies from A2-colored zirconia blocks and 45 crowns from CEREC blocks were prepared. Color measurements after 24 h of cementation (T1) and after cycles of aging of 1750 (T2), 3500 (T3), and 7000 (T4) in the thermal cycle device were made using SpectroShade Micro device. The coordinates of the color were used L*, a*, and b* as base and the color change was calculated with ∆ E00 in determining the color. One-way analysis of variance test was used to compare the times in terms of ∆ L*, ∆ a*, and ∆ b* values. Results: It was found that ∆ L* value decreased significantly in period of the T2, T3, and T4 times compared to T1 in all groups ( P < .05), whereas the change between period of T2, T3, and T4 times was not significant ( P > .05). The ∆ a* value increased significantly in the period of T3 and T4 times compared to T1 in the only G-CEM LinkForce group, whereas the ∆ b* value increased significantly in the period of T4 time compared to T1 in the only Panavia V5 group. The changes in ∆ E00 values, which were observed in all period of times, were found to be between 0.43 and 1.04, 0.43 and 1.43, and 0.40 and 0.97 in RelyX U200, G-CEM LinkForce, and Panavia V5 groups, respectively. Conclusion: After accelerated aging, it was found that the color of all cements became darker and the G-CEM LinkForce group turned red and the Panavia V5 group turned yellow. However, it was found that the color changes that occurred were within clinically acceptable visible levels.

The Microbial Neck: A Biological Review of the Various Implant–Abutment Connections

Aim: This study reviews the importance of selecting implant systems with connection designs that ensure better long-term prognosis of the prosthesis, thus placed. Materials and Methods: An electronic search on the PubMed database was done using MeSH keywords (“dental implant OR abutment OR connection AND microleakage OR bone loss”) to review English language articles published since the year 2011, which compared the crestal bone levels and microleakage around various implant–abutment connection designs (external hex, internal hex, and Morse taper). The search screened for articles on human trials and in vitro studies to be included within the review. Results: Based on the inclusion and exclusion criteria applied to the preliminary search, a total of four articles were included in the review for evaluating the influence of connection type on peri-implant bone loss, while nine articles were included to study the influence on bacterial leakage across the implant–abutment interface. Conclusion: Based on the studies reviewed, the conical connection design proved to be the most biologically stable junctional geometry because of the better microbial seal and the lesser micromovement observed in these types of implants during functional loading. Moreover, this review even emphasizes the need for more longitudinal clinical trials to assess the microbial seal of these connection designs within the actual oral environment to evaluate long-term changes in the peri-implant tissues, and subsequently even factor the prognosis of the planned prosthetic intervention.

Effect of Antioxidant and Buffering Agent Mixture on Dentin Shear Bond Strengths of Laminate Veneer and pH Change of External Medium After Intracoronal Bleaching

Aim: To investigate the effect of sodium ascorbate (SA), an antioxidant and calcium hydroxide (Ca(OH)2), a buffering agent mixture, on the shear bond strength of a luting resin to dentin, and pH changes of the extraradicular medium solution after intracoronal bleaching with hydrogen peroxide. Materials and Methods: In this in vitro study, 60 human maxillary central incisors were randomly assigned into six groups ( n: 10): Group 1: restored, no bleach; group 2: bleached, bonded immediately; group 3: bleached, treated with 10% SA applications before bonding; group 4: bleached, treated with calcium hydroxide applications before bonding; group 5: bleached, treated with CaOH2 and SA mixture applications before bonding; group 6: delay bonding by seven days. For bleach treatment in groups 2 to 6, intracoronal bleaching was performed with 35% hydrogen peroxide for four days. SA or CaOH2 or mixture of SA and CaOH2 were left in the access cavity for four days. Hybrid blocks, 4 mm × 4 mm wide × 2–mm thick, were luted with resin cements on dentin surface and then the specimens were subjected to shear bond strength testing. Analysis of variance and Tukey post hoc multiple comparison tests were applied ( P < .05). Results: G2 and G4 showed significantly low bond strength values and they were lower than the other groups ( P < .05). There were no significant differences between G1, G3, and G6 ( P > .05). The pH values had risen markedly in the groups containing calcium hydroxide (G4 and G5) after four days ( P < .05). Conclusion: The application of 10% SA or 10% SA and CaOH2 mixture were effective at reversing bleaching effects on bond strength. CaOH2 or CaOH2 and 10% SA mixture increased the external medium pH and were effective for alkalinization after intracoronal bleaching.

Influence of Apical Patency, Coronal Preflaring and Calcium Hydroxide on the Accuracy of Root ZX Apex Locator for Working Length Determination: An In Vitro Study

Aim: One of the main steps in a successful endodontic treatment is determining the correct working length (WL) of the root canal. In this regard, electronic apex locators (EAL) have been widely used for measuring the WL. The accuracy of EALs in determining the WL may be influenced by various factors. This study is aimed to evaluate the effects of apical patency, coronal preflaring, and calcium hydroxide on the accuracy of the EAL. Materials and Methods: In this in vitro study, 20 central incisor single-rooted human teeth with fully formed apex were considered. Then, samples were randomly divided into two study groups, ten samples in each group. The WL was determined and recorded at 0.5 mm distance to the apex using Root ZX apex locator before and after creating patency, coronal preflaring, and calcium hydroxide administration. All WLs were measured separately for each tooth and reviewed independently by two experienced operators with extensive experience in using EALs. Paired t test and Wilcoxon signed-rank test were applied and the significant level was at .05. Results: Statistical analysis of the obtained data showed a significant decline in the WL after apical patency and coronal preflaring ( P < .05). Moreover, WL exhibited a significant enhancement after calcium hydroxide application ( P < .05). Conclusion: Apical patency and coronal preflaring increased the accuracy of apex locators in determining the WL of the teeth. Besides, calcium hydroxide residues in the root canal reduced the accuracy of the apex locator.

Stress Analysis of Implant-Supported Removable Partial Denture with Anterior Fixed Prostheses and Conventional Implant-Supported Overdentures in the Edentulous Mandible

Aim: To compare new design implant-supported removable partial dentures retained with anterior fixed prosthesis with a conventional locater and bar attached implant overdenture prostheses retained by two or four implants via photoelastic stress analysis. Materials and Methods: Seven edentulous mandibuler acryclic models prepared and divided into two main groups; two to four implant models, subgroup separation as stated; for two implant models overdenture with locator attachment, crown design retained removable prosthesis with clasp retention, bridge design retained removable prosthesis with clasp retention, bridge design retained removable prosthesis with precision attachment retention; and for four implant models prosthesis with bar attachment overdenture, fixed bridge design retained removable prosthesis with clasp retention, fixed retained removable prosthesis with precision attachment retention. A 300 N load was applied to the first premolars. Photoelastic stress analysis method that is a specific method concerning stress visualization, and does not require statistical analysis, was used. The stress distributions were seen in optically using a poloriscope. Results: In the models with two implant-retained removable partial dentures, the stress distribution was found to be lower than that with the four implant-retained removable partial dentures. Nonsplinted implants caused high stress around the distal implant on the loading side. Conclusion: The stress loads were transmitted to other implants by splinting. Implant-supported removable partial dentures with an anterior fixed prosthetic design show lower stress distributions compared with bar retained prosthesis. These dentures appear to be advantageous in terms of stress transmission.

Indian Propolis Little Known and More to Explore for Dental Applications: A Review

Aim: The present trend in health care is toward the use of natural products for curing diseases. “Propolis” or bees wax is a natural, nontoxic resinous material collected by bees from exudates and buds of the plant. It has many beneficial biological and pharmacological properties such as antimicrobial, anti-inflammatory, antifungal, antiviral, and anticancer activities. Propolis is widely applied in dentistry as an anticariogenic agent, hypersensitivity reducing agent, and endodontic disinfection to name a few. The diverse phytochemical constituents of propolis are responsible for its valuable properties. Considering its vast potential, propolis has gained the attention of many researchers. The aim of this study is to offer a comprehensive evidence which will enable the readers and researchers to appreciate the prospects of the application of Indian propolis in present-day dentistry. Material and Methods: In vitro and in vivo studies on Indian propolis and its application in dentistry searches were performed in PubMed, Scopus, and Cochrane library databases up to December 2020. Results: The search identified 31 records; 12 full-text articles which met the eligibility criteria were assessed. Based on the results of in vitro studies, further in vivo studies need to be carried out to prove the feasibility of Indian propolis as an anticariogenic agent, a desensitizing agent, and an intracanal irrigant/medicament in the field of dentistry. Conclusion: Indian propolis has shown an immense amount of potentiality which demands for more clinical research to have sufficient evidence-based literature for future usage in oral health care.

The Effect of Cooling Times on the Bonding Between Porcelain and Metal Alloys Fabricated by Different Techniques: In Vitro Study

Aim: The aim of this study was to evaluate the effect of different cooling times on shear bond strength between cobalt–chromium metal frameworks fabricated by different techniques and veneering porcelain. Materials and Methods: One hundred twenty cobalt–chromium metal ceramic samples were obtained by three different techniques (casting, milling, and laser sintering). During the porcelain firing, fast and slow cooling protocols were applied. Ten specimens from each group were determined for all groups. The shear bond strength of the metal ceramic samples was measured by a universal testing machine with a constant crosshead speed of 0.5 mm/min. One sample from each group was evaluated by the scanning electron microscopy analysis in terms of surface change and fracture morphology. Variance analysis and Tukey test were used to analyze statistically significant differences between groups. Results: It was seen that the difference between the bond strengths of the metal frameworks obtained by different techniques was statistically significant ( P < .05). All groups except for difference between the bond strengths of all the frameworks metal groups with G-Ceram porcelain were statistically significant ( P < .05). The best bond strengths that were statistically significant were fast cooling G-Ceram (19.65 ± 2.65 MPa) with metal frameworks fabricated by laser sintering, fast cooling with metal framework fabricated by milling Noritake (19.17 ± 2.91 MPa), and the metal framework fabricated by casting was found to be slow cooling Noritake (12.99 ± 2.08 MPa) were seen. Conclusion: The porcelain cooling times had significant effect on the shear bond strength of porcelain to casting, milling and laser sintering alloys.