Dental Research Journal最新文献

Background: Pregnant women have poor knowledge of oral hygiene during pregnancy. One problem with the follow-up of dental caries in this group is zero accumulation in the decayed, missing, and filled teeth (DMFT) index, for which some models must be used to achieve valid results. The studied population may be heterogeneous in longitudinal studies, leading to biased estimates. We aimed to assess the impact of oral health education on dental caries in pregnant women using a suitable model in a longitudinal experimental study with heterogeneous random effects.

Materials and methods: This longitudinal, experimental research was carried out on pregnant women who visited medical centers in Tehran. The educational group (236 cases) received education for three sessions. The control group (200 cases) received only standard training. The DMFT index assessed oral and dental health at baseline, 6 months, and 24 months after delivery. The Chi-square test was used for comparing nominal variables and the Mann-Whitney U test for ordinal variables. The zero-inflated Poisson (ZIP) model was applied under heterogeneous and homogeneous random effects using R 4.2.1, SPSS 26, and SAS 9.4. The level of significance was set at 0.05.

Results: Data from 436 women aged 15 years and older were analyzed. Zero accumulation in the DMFT was mainly related to the filled teeth (51%). The heterogeneous ZIP model fitted better to the data. On average, the intervention group exhibited a higher rate of change in filled teeth over time than the control group (P = 0.021).

Conclusion: The proposed ZIP model is a suitable model for predicting filled teeth in pregnant women. An educational intervention during pregnancy can improve oral health in the long-term follow-up.

This systematic review and meta-analysis aimed to compare the efficacy of using platelet-rich fibrin (PRF) or connective tissue graft (CTG) for papilla reconstruction in the treatment of black triangles. A comprehensive electronic search across PubMed, Cochrane, Web of Science, ProQuest, and Scopus was conducted to identify the relevant randomized-controlled trials (RCTs), cohort studies, and case series. Quality assessment and meta-analysis were performed using R Statistical Software, focusing on the parameters such as papilla height, gingival index, plaque index (PI), clinical attachment level (CAL), and pocket probing depth. Registration number: CRD42022322934. From 191 initial studies, 7 were eligible for full-text review, with 4 RCTs and one retrospective study included in the meta-analysis. The analysis favored CTG over PRF in terms of black triangle height at 3-6 months postsurgery and in PI improvement at 3 months. No significant differences were found in CAL and probing pocket depth. While PRF can yield satisfactory results in papilla augmentation, CTG demonstrates superior clinical outcomes in specific parameters. Further research with more extensive clinical data is warranted.

Background: Smile esthetics can be subjective. This study aims to assess the effect of culture/geographic location on judging smile esthetics by comparing the perception of smile characteristics between American laypersons (Western culture) and Iranians (Eastern).

Materials and methods: One hundred residents from each country were recruited for this analytical cross-sectional study. A frontal picture of a posed smile with standard norms which are mentioned in the Contemporary Orthodontics textbook by William R. Proffit was selected. Adobe Photoshop 7 was used to alter midline diastema, gingival display (GD), maxillary midline-to-face discrepancy, buccal corridor (BC), and smile arc. Images were given to groups to determine the most attractive and acceptable smile. Data were analyzed by Chi-square, Mann-Whitney, and Spearman correlation coefficient in SPSS-22 (α =0.05).

Results: Americans were less critical in judging diastema (P < 0.001), GD (P = 0.013), and BC (P = 0.004) for smile attractiveness than Iranians. No difference was between the two groups in choosing the acceptability threshold and determining the most attractive smile except for BC (P = 0.002).

Conclusion: Overall, Americans were more tolerant of variations in smile characteristics than Iranians. Both groups agreed on most smiles. Therefore, it seems that it is reasonable to use similar standards for smile characteristics while considering the small differences.

Background: This study was designed to evaluate the antimicrobial activity of common gum protection and antiplaque toothpastes against Porphyromonas gingivalis (P. gingivalis) and Streptococcus oralis (S. oralis) as important periodontal pathogens.

Materials and methods: This experimental study investigated the antimicrobial activity of 15 commonly used toothpastes from different companies on the two common types of periopathogens, S. oralis and P. gingivalis . The antimicrobial activity of toothpaste was evaluated at three concentrations of 100%, 50%, and 25% and analyzed by agar well diffusion plate method and zone of inhibition. The obtained data were compared and statistically analyzed by SPSS software using one-way ANOVA and the least significant difference post hoc tests (α = 0.05).

Results: One-way ANOVA showed that the mean diameter of the two-bacterial zone of inhibition was significantly different at 100%, 50%, and 25% concentrations of toothpastes (P < 0.001). In general, the mean diameter of the zone of inhibition was greater at 100% concentration than the other two concentrations in all toothpastes. The highest zone of inhibition of the S. oralis was in the toothpastes containing tin. Further, the highest zone of inhibition of P. gingivalis was found in the triclosan-containing toothpastes.

Conclusion: Toothpastes containing triclosan had the most antimicrobial activity against P. gingivalis . Moreover, toothpastes containing tin compounds had the most antimicrobial effect against S. oralis .

Background: The presence of treatment-resistant microorganisms is known as the main cause of pulpectomy failure in the endodontic treatment of deciduous teeth. The usage of lasers can contribute to reducing these microorganisms. This study aimed to compare the effect of three disinfection methods for deciduous teeth canals using laser diode 810 nm, photodynamic therapy with laser 660 nm and methylene blue, and sodium hypochlorite.

Materials and methods: In this experimental study, 58 single-root deciduous teeth with no root resorption were investigated in four groups, including one control group of 10 and three intervention groups of 16. Preparation of the samples was done using manual files up to three numbers after the initial file. After sterilizing the samples in an autoclave, Enterococcus faecalis bacteria were cultured in the canals. In the first group, irrigating with hypochlorite 2.5% was done; in the second group, photodynamic therapy was performed using a laser diode and 0.1 mg/mL methylene solution; and in the third group, high-intensity laser 810 nm direct radiation was done into the canal. Next, samples were taken from all canals. The colony formation unit (CFU) of the bacteria was counted in the blood agar culture medium. The data were analyzed using Kruskal-Wallis and negative binomial regression test (α =0.05).

Results: The mean CFU differed significantly between the four groups. The rate of incidence of E. faecalis colonies showed a reduction in all three intervention groups compared to the negative control. In the high-intensity laser 810 nm group, there was 68.4%; in the photodynamic therapy with diode 660 nm and methylene blue, there was 88%; and in the hypochlorite group, 98.3% reduction was observed compared to the negative control group.

Conclusion: Based on the results of this study, to compare three disinfection methods of the deciduous teeth canals without preparation of canals, sodium hypochlorite had greater efficiency. All three groups of laser, photodynamic therapy, and sodium hypochlorite showed reductions of E. faecalis bacterial colony compared to the control group. The reductive effects of CFU were greater in the hypochlorite sodium group, followed by photodynamic and direct laser radiation groups.

Background: The aim of this study was to investigate the influence of abutment material, alveolar bone density, and occlusal forces on stress distribution around maxillary anterior implants.

Materials and methods: An in-vitro study was conducted. The maxillary anterior implant was modeled using a three-dimensional finite element model in D2 and D3 bones with three different abutment materials: titanium, zirconia, and poly-ether-ether ketone (PEEK). Von Mises stress was evaluated after the application of vertical and oblique loads of 100 N, 175 N, and 250 N. Statistical analysis was done by Friedman-Wilcoxon signed-rank test, Mann-Whitney U test, and Kruskal-Wallis test. The probability value <0.05 is considered a significant level.

Results: Stress distribution around D3 bone was higher than D2 bone in all the abutment materials with greater values seen in oblique load than vertical load with insignificant difference (P > 0.05). Statistically insignificant stress values were seen greater in PEEK than titanium or zirconia abutment (P > 0.05). A statistically significant difference was observed between 100 N and 175 N of load (P < 0.05).

Conclusion: PEEK, zirconia, and titanium as abutment material in the anterior region showed similar properties. The stress on the bone was proportionately increased during the vertical and oblique loads suggesting the influence of mechanical load in crestal bone loss rather than the type of abutment material.

Background: The additive manufacturing technology made the topology optimization technique feasible. This technique can indefinitely reduce the weight of the printed items with a promising increase in the mechanical properties of that item.

Materials and methods: In the current experimental study, 50 samples were fabricated for a 3-point bending test. They were divided into (n = 5) as a control Group 1 free of internal geometries, (n = 15) for each of Groups 2-4, and they were subdivided into (n = 5) for each percentage of reduction per volume (10%, 15%, and 20%). Spherical, ovoid, and diamond shapes were each group's fundamental geometries, respectively. Cylindrical tunnels connected the voids in each group. Radiographic images were performed to validate the created geometries, the weight was measured, and flexural strength and modulus of elasticity were calculated. Data were analyzed by one-way ANOVA and Duncan's post hoc tests at P < 0.05.

Results: The weight results showed a significant reduction in mass. The flexural strength of Group 2 at a 10% reduction per volume had the highest mean significantly without compromising the elastic modulus. In comparison, the means of group 4 at 20% reduction showed the lowest level of toughness.

Conclusion: The weight was reduced according to the reduction percentage. The flexural strength of Group 2 at a 10% reduction showed the highest degree of toughness among all groups. The void shape and density influenced the mechanical properties tested.

Background: Tissue fixation is a crucial step to preserve the tissues in a life-like state with minimal disruption to its cellular and chemical composition for histopathological examination. The search for an effective alternate tissue fixative to the routinely used formaldehyde has gained interest as constant exposure to formaldehyde has proven to be toxic. Honey, an organic substance with high acidity and hygroscopic nature, exhibits tissue fixative properties and has been used in the present study. The present study aimed to standardize honey as a tissue fixative for histopathology by comparing it with formalin.

Materials and methods: In vitro study Oral tissue samples of goat were fixed in 10% honey and 10% formalin solution, respectively, for 24-48 h, followed by routine tissue processing and microscopic examination of 37 slides per group. 2200 epithelial cells (1100 per group) were selected for the computer-aided morphometric image analysis (Fiji-Image J) by three observers. Cell area (CA), cell perimeter (CP), nuclear area (NA), nuclear perimeter (NP), cytoplasmic area (Cyt A), and nuclear-cytoplasmic ratio were the parameters studied. Mann-Whitney U-test (STATA/IC version 16) for inter-group comparison was done and P < 0.05 was considered statistically significant.

Results: The probability of epithelial cells in the honey-fixed group to have greater NA, NP, and N/C ratio was about 50%-60%. The probability of epithelial cells in formalin-fixed tissues to have greater CA, CP, and Cyt A was about 70%.

Conclusion: Honey is a better nuclear fixative than formalin. Cytoplasmic shrinkage of epithelial cells should be taken into consideration while fixing tissues with honey.