The Efficacy of Different Laser Applications on Dentin Sealing in Preventing Discoloration Induced by Mineral Trioxide Aggregate.

The aim of this in vitro study was to evaluate the effect of the pre-application of a dentin-bonding agent and the application of different lasers on the prevention of tooth discoloration caused by mineral trioxide aggregate (MTA) in the presence of blood. Sixty extracted human anterior teeth were selected, with root lengths standardized to 10 mm and root canals shaped using Gates-Glidden drills #3 to #5. The samples were divided into six groups (n = 10): Group 1 with no surface treatment and Groups 2 to 6 with Optibond universal adhesive and Neodymium yttrium aluminum garnet (Nd:YAG), Erbium yttrium aluminum garnet (Er:YAG), Erbium-chromium-yttrium-scandium-gallium-garnet (Er:Cr:YSGG), and diode laser applications, respectively. Root canals were filled with fresh human blood, and ProRoot MTA and a collagen barrier were then placed. Color changes were measured with a spectrophotometer at 0, 7, 30, 90, and 180 days post MTA placement. Color differences (∆E) were analyzed using a two-factor mixed-design ANOVA with the Sidak method (p = 0.05). All treatment groups exhibited discoloration above the acceptability threshold. Although all treatment approaches exhibited less color change compared to the control group (p < 0.05), there was no significant difference among them in terms of preventing color change (p > 0.05). It was determined that none of the methods could guarantee 100% prevention of discoloration caused by MTA-blood contact.

Resistance to fracture of simulated external cervical resorption cavities repaired with different materials.

The aim of the study was to evaluate the fracture resistance (FR) of teeth with simulated external cervical resorption (ECR) cavities repaired with different materials. Following the shaping of the 80 human permanent maxillary central incisors, standard ECR cavities were prepared and restored with a nanohybrid composite resin; a high viscosity GIC Equia Forte Fill; Biodentine; Biodentine + nanohybrid composite resin; MTA BIOREP; MTA BIOREP + nanohybrid composite resin. Then, the root canals were obturated with AH Plus and gutta-percha. The roots were embedded acrylic resin blocks and fracture strength test was applied. The highest FR was observed in the Biodentine group, while the lowest was in Equia group (p < 0.05). No significant results were observed among composite, Biodentine + composite, MTA BIOREP + composite and MTA BIOREP (p > 0.05). Biodentine may be a preferable material for repairing ECR cavities. Adding a composite layer on MTA BIOREP and Biodentine did not improve the FR of these materials.

Examination of caries-affected dentin and composite-resin interface after different caries removal methods: A scanning electron microscope study.

To evaluate the caries-affected dentin and composite-resin interface with scanning electron microscopy (SEM) after different caries removal methods in human molars. Twelve with extensive approximal caries lesions that did not reach the pulp and five caries-free molars (control group [CG]) were used. Carious teeth were divided into four experimental groups: Atraumatic Restorative Treatment (ART), Rotary Instrument (RI), Photo-Ablation, and Papain-Based Enzymatic Gel (Brix 3000®, Brix, Brazil). Class II slot cavities were prepared with RI in the CG. Then all caries removed teeth and control groups were restored (All-Bond Universal, BISCO, USA; Clearfil MajestyES-2, Kuraray, Japan). Specimens were prepared for SEM examinations. Hybrid layer (HL) thicknesses were measured using ImageJ programme. Gap measurements were performed with micro-CT. Data were analyzed with ANOVA and posthoc Dunnett's t-tests (p < .05). The highest HL thickness was found in Photo-Ablation Group, and a statistically significant difference was observed among the control and experimental groups (p < .05). The lowest HL thickness was measured in the Enzymatic Gel Group. In terms of internal gap formation, CG showed statistically significant differences compared to the other groups (p < .05). The highest internal gap was observed in RI Group, while the lowest gap was observed in CG. According to SEM, a uniform HL and resin tags were seen in the CG. Smear layer, irregular HL, and gap formation were observed in ART Group. In RI Group, nonuniform HL formation and resin tags were observed. In Photo-Ablation Group, a uniform HL without smear layer and internal gap was observed. In the Enzymatic Gel Group, both opened dentinal tubules, and melting-like formations were observed on the dentin surface. Especially melting-like formations were observed in peritubular dentin. It can be concluded that all caries removal methods except rotary instrumentation were conservative methods, which preserve more healthy dental tissues. RESEARCH HIGHLIGHTS: Among the caries removal procedures, the photo-ablation caries removal method stands out with the highest hybrid layer (HL) thickness and the lowest internal gap formation. Despite having the lowest HL thickness, the enzymatic gel method can be advantageous for patients requesting an alternative caries removal instead of a rotary instrument.

Perceptions of dental students towards online education during the COVID-19 pandemic.

PURPOSE: This study evaluated the usage habits, attitudes, and perceptions of undergraduate dental students toward distance (online) learning and identified variables related to those attitudes. MATERIALS AND METHODS: The study included 1,605 undergraduate dental students who participated voluntarily. The data collection tool consisted of a distance learning attitude scale, a questionnaire on personal information, and open-ended questions. The perceptions of dental students to distance education according to the year and type of dental school they attended were evaluated. RESULTS: Most students expressed that distance learning in dental courses was not as effective as traditional face-to-face education (59.1%, n=949). While students studying at state universities had a more negative view of distance education, the satisfaction scores of the first-year students were found to be significantly lower than the other students (p<0.05). CONCLUSION: Dental students were generally unhappy with the interruption of traditional education caused by COVID-19 and having to continue their education online. However, under the circumstances, they saw it as an advantage allowing them to continue their education and avoid a complete suspension.