The effect of antimicrobial peptide-added adhesive resins on shear bond strength and the adhesive remnant index of orthodontic brackets.

OBJECTIVES: The aim of this study was to evaluate the effect of in-vivo produced Nisin which is an antimicrobial peptide (AMP) added to adhesive resin on shear bond strength (SBS) and the adhesive remnant index (ARI) of orthodontic brackets. METHODS: Bacterial AMP was produced by fermentation and the ideal AMP/Bond concentration and antimicrobial efficacy of the mixture were tested. To evaluate the SBS and ARI scores of AMP-added adhesive resins, 80 maxillary premolar teeth extracted for orthodontic purposes were used and randomly assigned into 2 groups (n = 40). Group 1: Control Group (teeth bonded with standard adhesive resin); Group 2: Experimental Group (teeth bonded with AMP-added adhesive resin). Statistical analysis was performed using the SPSS package program and applying the Mann-Whitney U and Fisher's exact tests. P < 0.05 was considered as statistically significant. RESULTS: Nisin synthesized in-vivo from Lactococcus lactis (L. lactis) (ATCC 7962) bacteria was provided to form a homogenous solution at an ideal concentration To find the minimum AMP/Bond mixture ratio that showed maximum antimicrobial activity, AMP and Bond mixtures were tested at various concentration levels between 1/160 and 1/2 (AMP/Bond). As a result, the optimum ratio was determined as 1/40. The antimicrobial efficacy of Nisin-added adhesive resin was tested against Streptococcus mutans (S. mutans) (ATCC 35,688) and Lactobacillus strains (cariogenic microorganisms). AMP formed a 2.7 cm diameter zone alone, while 1/40 AMP-bond mixture formed a 1.2 cm diameter zone. SBS values of the teeth bonded with Nisin added adhesive (17.49 ± 5.31) were significantly higher than the control group (14.54 ± 4.96) (P = 0.004). According to the four point scale, Nisin added adhesive provided a higher ARI score in favour of the adhesive and tooth compared to the control group (ARI = 3, n = 20). CONCLUSIONS: Nisin produced from L. lactis (ATCC 7962) had greater antimicrobial effects after mixing with adhesive bond against cariogenic microorganisms S. mutans (ATCC 35,688) and Lactobacillus strains. Nisin added adhesive increased shear bond strength (SBS) of orthodontic brackets and ARI scores in favor of adhesive & teeth. CLINICAL RELEVANCE: Clinicians should take into account that using Nisin-added adhesive resin in orthodontic treatments can provide prophylaxis against tooth decay, especially in patients with poor oral hygiene.

Color Alterations, Flexural Strength, and Microhardness of 3DPrinted Resins Treated in Different Coloring Agents.

Purpose This study evaluated the color alterations, flexural strength and microhardness properties of two different 3D-printed permanent crown resins. Materials and Methods Samples were produced from two different 3D Print permanent crown resins: Group 1 (Saremco Crowntec; Saremco, Switzerland), Group 2 (P-crown Version 2; Senertek, Turkey). Color changes (ΔE values), flexural strenght and vickers hardness number of the samples were calculated. Data were analyzed with Shapiro-Wilk normality test, Independent-t test, and Mann Whitney-U tests. Significance level was accepted as P<0.05. Results ΔE values for red wine were found to be significantly higher in Group 1 (6.43Å}2.26; P<0.001). The flexural strength values (MPa) of Group 1 were significantly higher than Group 2 in all three solutions (P<0.001). There was no significant difference between the VHN values of the samples kept in wine and coffee solutions (P= 0.271; 0.827). Conclusion 3D printing resins are affected at different levels by coloring solutions. Microhardness and flexural strength of 3D print samples kept in different coloring agents are different.In the use of 3D printing resins, product selection should be made by taking into account the individual factors such as the eating and drinking habits of the patients and the physical properties expected from the sample.

Comparison of the Flexural Strength of Three Different Aged and Nonaged 3D-Printed Permanent Crown Resins.

AIM: The aim of this study was to evaluate the flexural strength properties of three different aged and nonaged 3D-printed resins built by different 3D printing systems used in dental applications. MATERIALS AND METHODS: Bars (2 × 2 × 25 mm) were additively fabricated using a 3D printer and different dental crown resins (Saremco Crowntec, Senertek P-Crown V2, and Senertek P-Crown V3) per the manufacturers' recommendations. Each subgroup was divided into aged and nonaged subgroups (n = 10 bars per group). Thermocycling procedures (5° to 55°C; 5,000 cycles) were performed under favorable conditions for the aged subgroups from each material. Flexural strength (MPa) was measured in all samples using a universal test machine. RESULTS: When both aged and nonaged resins are compared, significant differences were found in flexural strength measurements (P < .001). The highest flexural strength was observed in the Saremco Crowntec group, while the lowest flexural strength was observed in the Senertek P Crown V2 group. The flexural strength measurements of Saremco Crowntec and Senertek P Crown V3 displayed no significant difference between their aged and nonaged groups (P > .05), while Senertek P Crown V2 (P = .039) showed significant differences between its aged and nonaged groups. CONCLUSIONS: Saremco Crowntec showed the highest flexural strength both in aged and nonaged groups, while Senertek P Crown V2 had the lowest strength. The artificial aging process decreased flexural strength values in all 3D-printed resin groups.

Evaluation of mandibular osseous structure in patients with mandibular asymmetry: a fractal analysis study.

OBJECTIVE: We evaluated the effect of mandibular asymmetry on the trabecular structure of the mandible as measured through fractal analysis (FA). STUDY DESIGN: We divided a sample of 105 patients with skeletal class I occlusion, cervical vertebral maturation CS6, and skeletal vertical dimension ratios within normal limits into right asymmetric, left asymmetric, and symmetric groups. We performed FA on 6 bilateral regions of interest on panoramic radiographs of the patients and calculated the mean fractal dimension (FD) for each region. We performed the Wilcoxon signed-rank and paired t tests to compare the significance of differences in FD between sides within each group and between groups for all regions. Statistical significance was established at P < .05. RESULTS: We found statistically significant differences in mean FD values between the right and left condyles of the 2 asymmetric patient groups. The FD was greater in the left condyle of patients with right asymmetry and in the right condyle of patients with left asymmetry. The right condyle had a significantly greater FD in left asymmetric patients than in right asymmetric patients. CONCLUSIONS: The results of FA indicate that asymmetry is characterized by an increase in the mean FD of the condyle that is responsible for the asymmetry. Fractal analysis can be a valuable diagnostic technique in distinguishing trabecular differences in the condylar areas of asymmetric individuals.

Factors of life satisfaction and happiness among dentists: A cross sectional study.

Objectives: The present study aimed to determine the levels of happiness among dentists and to investigate their associations with emotional well-being and satisfaction with life. Methods: Dentists in Turkey were surveyed with 25 questions on age, gender, place of work, and years of experience, and a five-item life satisfaction scale. Results: A total of 486 dentists completed the survey. Dentists' workplaces and professional titles were associated with their life satisfaction scores. Most dentists (n = 373; 76.25%) reported feeling pressured in their work environment, and the institution where they worked was significantly associated with the degree of pressure (p < 0.001). Institution (p < 0.001), job title (p < 0.001), and work experience (p < 0.019) were significant factors in whether they would recommend their profession to others. Dentists' institutions and titles were significantly associated with life satisfaction (p < 0.001). Conclusions: Our findings suggest that dentists in Turkey have a low life satisfaction with respect to that of other professionals and dentists from other countries. In addition, the factors associated with life satisfaction vary.