Frontiers in Dentistry

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Objectives: This study aimed to do a comprehensive systematic review on the comparison of digital and conventional workflows regarding prosthetic outcomes, accuracy of implant impressions, framework passivity and fit, and clinical fabrication of multi-unit implant-supported fixed restorations.

Materials and Methods: The EMBASE, PubMed, Scopus, and Cochrane Library databases were searched for relevant articles published up until April 2020.

Results: No in-vivo article was found to compare full digital and conventional workflows regarding the accuracy of implant impressions, passivity and fit of frameworks, and prosthetic outcomes. There was no study to investigate full digital and conventional workflows for clinical fabrication of multi-unit implant-supported fixed restorations.

Conclusion: This empty review highlights the need for further research to compare full digital and conventional workflows for implant-supported restorations.

Objectives: Fibroblasts are among the most critical connective tissue cells in almost all tissues and organs. Enhancement of fibroblast differentiation, proliferation, and morphogenesis is of paramount importance in tissue regeneration and wound healing. The non-thermal dielectric barrier discharge (DBD) plasma technology has recently gained interest due to its extensive applications and multiple biological effects. This review article outlines the applications of DBD plasma in dentistry, and its biological effects on human fibroblasts.

Materials and Methods: Relevant keywords were searched in PubMed, Ovid, and Google Scholar online databases. The search strategy resulted in selection of 7 studies according to the eligibility criteria.

Results: Most studies reported increased cell proliferation and viability after the application of DBD plasma. Four studies that focused on the development of adhesion-related appendages examined the morphology of fibroblast cells, including the creation of vinculin, protrusion, and actin cytoskeleton. Expression of cyclin D1/P27 genes and genes associated with adhesion and cell attachments was also reported in two studies.

Conclusion: This narrative review discussed the effects of DBD plasma technology on proliferation and behavior of human fibroblasts, and reviewed the available articles in this regard. More in vivo studies are required to understand the exact effects of this emerging technology on human mesenchymal tissues

Objectives: Endodontic treatment of immature teeth poses a significant challenge, especially in achieving a proper seal using traditional obturation methods. Revascularization presents itself as an alternative approach to this problem, and the application of triple antibiotic paste (TAP) has been suggested as a means to achieve disinfection during the procedure. This study aims to compare the antibacterial properties of three different antibiotic combinations to assess their effectiveness on root canal disinfection.

Materials and Methods: Eighty samples were employed to assess the impact of three antibiotic combinations on Enterococcus faecalis, Escherichia coli, Streptococcus mutans, and a combination thereof. The antibiotics included metronidazole, ciprofloxacin, and cefaclor (CCM), the commonly used TAP, and a double antibiotic paste (DAP) composed of metronidazole and ciprofloxacin. Dentin shavings collected using Gates-Glidden drills were placed in microtubes containing a 2ml standard bacterial suspension. Microtube contents were diluted and cultured on BHI agar plates, with colony counts calculated based on dentine shavings' weight in CFU/mg. Kruskal-Wallis and Dunn’s post-hoc tests were used for statistical analysis and P<0.05 was considered significant.

Results: A significant difference in mean CFU was observed among all bacterial groups (P<0.05). Dunn's post-hoc analysis showed a significant difference only between the control group (methylcellulose) and the other antibiotic groups. There was no significant difference between the other antibiotic groups in two-by-two comparisons.

Conclusion: There was no significant difference in the antimicrobial properties of DAP, TAP and CCM. Therefore, DAP and CCM may be used during regenerative treatment.

Objectives: Pregnancy can lead to oral health issues, yet many women remain unaware of the potential negative impact on their pregnancy. This study aimed to assess the dental and periodontal health of pregnant women in Tehran, Iran, and identify its associated factors.

Materials and Methods: A cross-sectional study was conducted with 221 pregnant women attending 12 randomly selected public health centers in Tehran, Iran. A self-administered questionnaire gathered data on background characteristics, oral health knowledge, and self-reported health. Periodontal status, oral hygiene, and dental health were assessed using bleeding on probing (BOP), simplified oral health (OHI-S), and decayed-missing-filled teeth (DMFT) indices. Statistical analysis included simple and multiple linear regression (P<0.05).

Results: The participants' ages ranged from 18 to 42 years (mean: 27.9 years, SD: 5.5). On average, participants scored 4.1 out of 11 (SD: 1.7) for general oral health knowledge and 1.62 out of 4 (SD: 0.9) for knowledge about oral health during pregnancy. The mean DMFT was 8.28 (SD: 5.7), with 65.6% of women having fair oral hygiene according to the OHI-S. Participants reporting poor general health had more debris (B: 0.276, P=0.043), while those with higher general oral health knowledge had fewer missing teeth (B: -0.183, P=0.048).

Conclusion: Despite partial free oral health care provided to pregnant women in Iran, the dental and periodontal conditions of the participants were unsatisfactory. Implementing motivational educational programs within the primary health care system could be instrumental in improving the oral health of pregnant mothers.

Objectives: Antibacterial activity against endodontic pathogens is a desirable feature for root canal sealers. The objective of this study was to compare the antibacterial effect of three resin-based endodontic sealers (AH26, Adseal, and Beta RCS) against Enterococcus faecalis in vitro.

Materials and Methods: The antibacterial properties of the sealers were assessed against E. faecalis using agar diffusion test (ADT) for fresh state (N=10) and direct contact test (DCT) for freshly-mixed and set states of the materials (N=10). In ADT, the diameter of the zones of inhibition was measured after 24h of contact. In DCT, the colony-forming units of the bacteria were counted after 30 minutes and 180 minutes of exposure. The results were analyzed with two-way ANOVA and independent sample t-test. P<0.05 was considered significant.

Results: Regarding DCT results, all test materials indicated an antibacterial effect, both in freshly-mixed and set states. The highest antibacterial effect was related to Adseal, whereas the lowest was observed in Beta RCS. There was a significant difference between all study groups (different sealers, setting states, and contact times; P<0.001), except for freshly-mixed AH26 and Adseal at 180 minutes (P>0.05). According to ADT, AH26 and Adseal represented the widest and the smallest inhibition zones, respectively (P<0.001).

Conclusion: Within the limitations of this in vitro study, AH26, Adseal, and Beta RCS showed antibacterial effects against E. faecalis in both freshly-mixed and set states. The antibacterial effect increased over time in all of the studied sealers.

Objectives: Sublingual varices are characterized by abnormally dilated veins. Some systemic conditions such as cardiovascular disease have been suggested to be associated with sublingual varices. Due to the convenience in examining the sublingual area, the present study aimed to assess the relationship between sublingual varices and hypertension.

Materials and Methods: In this descriptive-analytic study, 500 patients were categorized into two groups: those with sublingual varices and those without. Two oral medicine specialists assessed the lesions, and the blood pressure of all patients was measured while they were in a relaxed sitting position. Age and gender data were recorded for all participants. Statistical analysis included t-test, chi-square, and logistic regression, with significance set at P<0.05.

Results: The frequency of sublingual varices was 21.8%. Mean systolic blood pressure was 139.68±19.01mmHg in patients with sublingual varices and 118.09±13.78mmHg in patients without the lesions (P=0.561). Mean diastolic blood pressure was 100.45±17.81mmHg and 80.31±12.08mmHg in patients with and without sublingual varices, respectively (P<0.001). Smoking was significantly more prevalent among patients who had the lesions (P<0.05). Gender (P=0.686) and age (P=0.875) showed no significant relationship with sublingual varices, while smoking and blood pressure levels were significantly associated with these varices (P<0.001).

Conclusion: It is advisable to monitor and manage blood pressure in patients with sublingual varices who may not be aware of their blood pressure status. Our results showed that smoking could be one of the predictive factors for sublingual varices.

Objectives:  Durable bonding to zirconia is a challenging issue in dentistry. This study aimed to assess the effect of bioglass coating of zirconia on the microshear bond strength of resin cement to zirconia and to study the effect of thermocycling on this bond.

Materials and Methods: This in-vitro experimental study was conducted on 60 yttria-stabilized tetragonal zirconia blocks in six groups (N=10) based on surface pretreatment and thermocycling. Surface pretreatments included no treatment control, alumina particle abrasion, and bioglass-coating of zirconia. Resin bonding was performed with Panavia F2.0 cements. Then, half of the specimens underwent a 24-hour incubation in 37°C water, while the other half were subjected to thermocycling (12000 cycles, 5-55°C, 60s for each batch) following the same incubation period. Subsequently, the microshear bond strength of the specimens was measured. Additionally, one block from each group was subjected to scanning electron microscopy and X-ray diffraction. The data were analyzed using Kruskal-Wallis and Mann-Whitney U tests.

Results: There was a significant difference between the bond strength values of different groups (P<0.001). Alumina particle abrasion and bioglass coating equally increased the bond strength compared to the untreated control group (P<0.001). Thermocycling caused significant decreases in bond strength in all the groups (P<0.001); however, the bond strength value of the thermocycled bioglass-coated group was significantly higher than that reported for the thermocycled alumina particle abraded group (P=0.015).

Conclusion: Despite the decrease in the bond strength values after thermocycling, the long-term efficacy of the bioglass coating of zirconia was promising.

In August 2017, six international senior dental researchers published a critical declaration called ‘La Cascada; Dentistry in Crisis: Time to Change’. This statement outlined major concerns with the current trajectory of the dental profession and proposed recommendations for change. This study piloted an online survey among an exploratory convenience sample of 138 Iranian dentists, ensuring a suitable gender mix and a representative mix of generalists and specialists. The questionnaire included two main questions about the respondents’ agreement with the declaration and some of the recommendations. The majority (72.2%) of the 138 participants expressed agreement with the messages of the La Cascada Declaration by selecting 4 or 5 on a 5-point Likert scale. However, there was not a strong consensus among participants regarding all six selected recommendations. In conclusion, it appears that groups of dentists agree that the dental profession is facing a crisis. However, the profession has not yet reached a consensus on solutions.

Objectives: The reduction of resistance to sliding between the archwire and bracket promotes more seamless tooth movement, leading to a faster and improved orthodontic treatment experience. This research aimed to examine how the degradation of elastomeric modules, different ligation methods, bracket-wire angle, and wire type (nickel titanium, NiTi or stainless-steel, SS) impact the kinetic friction resulting from the interaction between NiTi or SS archwires and SS brackets.

Materials and Methods: The current in vitro study was conducted on nine groups, including NiTi and SS archwires with three types of ligations (O-ring, figure of 8, and SS wire ligature) and two bracket-wire angles (0˚ and 10˚). The kinetic friction in each group was measured using a Universal Testing Machine at four time intervals: baseline, day one, week one, and week four. Repeated measures ANOVA, Mauchly test of sphericity followed by the Greenhouse-Geisser test, and relevant post hoc tests were used for statistical analysis (P<0.05).

Results: The authors found a decrease in kinetic friction in all types of ligations, which confirmed the effect of time on the degradation of ligation modules. The kinetic friction of figure of 8 ligations was higher than both O-ring and SS wire ligations. No difference was observed between O-ring and SS wire ligations. Furthermore, the bracket-wire angle did not affect friction.

Conclusion: The authors suggest that the use of figure of 8 ligations in NiTi and SS wires should be limited due to their high friction and replaced with other types of ligations, if possible.

Objectives:  This study assessed the effects of two remineralizing agents namely MI Paste Plus containing casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACFP) and Remin Pro containing hydroxyapatite, fluoride and xylitol (HFX) with/without erbium-doped yttrium aluminium garnet (Er:YAG) and CO₂ laser irradiation on demineralized enamel microhardness.

Materials and Methods: In this in vitro study, 70 sound human premolars were mesiodistally sectioned, demineralized at a pH of 4.6 for 8 hours, and randomly divided into 7 remineralization groups (n=10): of (I) MI Paste Plus (CPP-ACFP), (II) Remin Pro (HFX), (III) MI Paste Plus+CO₂ laser (0.7 W power, 50 Hz), (IV) Remin Pro+CO₂ laser, (V) MI Paste Plus+Er:YAG laser (1 W power, 10 Hz), (VI) Remin Pro+Er:YAG laser, and (VII) negative control. The Vickers hardness number of specimens was then measured. The groups were compared by one-way ANOVA and Tukey’s test (α=0.05).

Results: The mean microhardness was 319.8±49.9, 325.3±44.6, 359.4±35.7, 296.4±33.7, 319.9±58.1, 358.9±28.4, and 240.0±41.6 kg/mm2 in groups 1 to 7, respectively. The difference in microhardness was significant among the groups (P<0.0001). Pairwise comparisons revealed significant differences in microhardness between all groups (P≤0.03) except between groups 1 and 2, 1 and 5, 2 and 5, and 3 and 6 (P>0.05).

Conclusion: Both Remin Pro (containing HFX) and MI Paste Plus (containing CPP-ACFP) can cause enamel remineralization.  MI Paste Plus+CO₂ laser irradiation and Remin Pro+Er:YAG laser irradiation were significantly more effective than the application of each remineralizing agent alone.

Objectives: In an ideal pulpotomy, the radicular pulp remains vital, healthy, and fully encased within an odontoblastic layer. Mineral trioxide aggregate (MTA) and bone morphogenetic proteins (BMPs) have been suggested to facilitate this outcome. We aimed to compare the clinical and radiographic failure and success rates of MTA and rhBMP2 as pulpotomy medicaments.

Materials and Methods: Sixty-eight teeth from 3–6-year-old children were randomly assigned to two groups using a split-mouth design. Cervical pulpotomy was performed using MTA in one group and rhBMP2 in the other. Subsequently, the teeth were restored with stainless-steel crowns. Clinical and radiographic assessments were performed at 3, 6, 9, and 12-month follow-up intervals to evaluate success and failure rates. Data were analyzed using Chi-square test and Kaplan-Meier survival analysis (P<0.05)

Results: At six and nine months, one tooth in the BMP2 group and one tooth in the MTA group showed internal resorption, respectively. After 12 months, one tooth in the BMP2 group exhibited PDL widening. The radiographic success rate was 100% for the MTA- and 97.1% for the BMP2-group at six months, 96.7% for both groups at nine months, and 96.7% and 93.3%, respectively, at 12 months. No clinical failure criteria were observed in any of the teeth. Survival analysis revealed no significant difference between the two groups.

Conclusion: The study reveals comparable outcomes between rhBMP2 and MTA, suggesting rhBMP2 as a viable alternative for pulpotomy in primary teeth. With minimal incidences of complications and no significant differences noted, rhBMP2 demonstrates potential for clinical use.

Objectives: This study assessed the effect of chlorhexidine (CHX) and isopropyl alcohol (IA) on immediate and late pushout bond strength (PBS) of fiber posts to dentin.

Materials and Methods: In this in vitro study, 54 single-canal premolars were endodontically treated, and randomly assigned to 3 groups (N=18) for root dentin conditioning with distilled water (control), 2% CHX, and 70% IA after post space preparation. Fiber posts were cemented with TheraCem self-adhesive cement, and each group was subdivided into two subgroups (N=9) for PBS measurement immediately after bonding, and after  5000 thermal cycles (5-55°C). The roots were then sectioned, and their PBS was measured. The mode of failure was evaluated under a stereomicroscope at ×40 magnification. Data were analyzed by repeated measures ANOVA and Tukey’s test (alpha=0.05).

Results: The highest PBS was noted in the IA group (21.12 MPa) after 24 hours and the lowest PBS belonged to the control group after thermocycling (7.48 MPa). The immediate and post-thermocycling PBS were significantly lower in the control group than the CHX group (P<0.05). The PBS in both the control and CHX groups was lower than that in the IA group (P<0.001).  Regardless of the type of detergent, a significant reduction in PBS was observed after thermocycling (P<0.003). The PBS significantly decreased from the cervical towards the apical region in all groups (P<0.001).

Conclusion: According to the results, application of IA before the self-adhesive cement effectively improved the immediate and late PBS, and was significantly more effective than CHX.

Objectives: Teeth bleaching is an accepted and modern treatment in cosmetic dentistry. Bleaching agents may affect amalgam restorations and increase mercury release; therefore, patients are at increased risk of mercury exposure in the body. The aim of this study was to investigate the effect of polishing and universal bonding application on mercury release from aged amalgams exposed to bleaching.

Materials and Methods: In this in-vitro experimental study, 64 dental amalgam specimens with dimensions of 3×5×10 were prepared and divided into two experimental and control groups. Each group was further divided into 4 subgroups and received one of the following treatments: no intervention, surface bonding, polishing, or polishing and surface bonding. Subsequently, the samples were immersed in bleaching agent containing 7% hydrogen peroxide and the amount of mercury released after 96h was measured. The results were analyzed by two-way ANOVA and Tukey post hoc tests (α≤0.05).

Results: The results showed that the type of solution (P<0.05) and surface treatment (P<0.001) significantly affected the level of mercury release. However, there was no significant interaction between surface treatment methods in the bleaching group and those in the phosphate buffer group (P=0.621).

Conclusion: Bleaching agents were found to enhance mercury release from dental amalgam. The application of polishing and universal bonding on amalgam surfaces exhibited significant effects on the reduction of the mercury release.

Objectives: This study aimed to evaluate radiofrequency-induced heating of different amalgam restorations and dental implants during 1.5T magnetic resonance imaging (MRI).

Materials and Methods: Standardized class I cavities (5 mm long, 3 mm wide, and 3 mm deep) were prepared on the occlusal surface of 45 extracted human third molars. The samples were restored by three different types of amalgam including Cinalux amalgam (non-gamma-2, spherical), GS-80 (non-gamma-2, admix), and GK-110 amalgam (non-gamma-2, admix in silver). As a separate intervention group (G4), five titanium mini drive-lock implants with 2mm diameter and 10mm length were also selected and mounted to the base of the Eppendorf tube with 3mm of the implants extending above the mounting putty. The box containing the specimens was placed parallel to the long axis of the standard head and neck coil of the MRI device (64MHz radio-frequency energy with 25kW amplifier, 1.5T). Temperature fluctuations of the metallic materials in each group were monitored during MRI scans using a calibrated thermometer. One-way ANOVA was used to compare temperature changes among the amalgam groups (P<0.05).

Results: Temperature elevations ranged from 0.21°C to 0.70°C in amalgam restorations and from 0.35 to 0.47°C in dental implants. The temperature changes among the three amalgam agents were not statistically significant.

Conclusion: According to our findings, the radiofrequency-induced heating of amalgam restorations and dental implants during MRI examination can be considered within acceptable ranges. Therefore, amalgam restorations and dental implants can be categorized as "MR safe" in terms of radiofrequency-induced heating during 1.5 T MRI.  

Objectives: Evaluation of the effect of grinding on flexural strength of zirconia after low temperature degradation (LTD) and pH-cycling.

Materials and Methods: Sixty-four bar-shaped specimens of yttria-stabilized tetragonal polycrystalline zirconia were milled, sintered, wet-polished, and divided into 8 groups (N=8). The four control groups were not aged while artificial aging was performed in the 4 experimental groups in three steps including  LTD in steam for 40h, pH-cycling, and tooth brushing for artificial aging. All groups underwent surface preparations as follows: standard polishing without surface treatment (Sp), grinding with a blue-yellow band diamond instrument (Gr); grinding with a diamond rotary instrument (DRI) and then over-glazing (Gl); grinding with a DRI followed by two-step intraoral polishing (Po); standard polishing and aging (Sp-Ag); grinding and aging (Gr-Ag), grinding, over-glazing and aging (Gl-Ag); and grinding, polishing and aging (Po-Ag). Monoclinic content was assessed in one specimen of each group by X-ray diffraction (XRD). The 3-point flexural strength test was performed in a universal testing machine. The results were analyzed with two-way ANOVA and Tukey’s test (α=0.05).

Results: Mean flexural strength (Mpa) was significantly higher in groups Gr and Po compared to group Sp (both, P<0.0001) and group Gl (both, P<0.0001). In XRD analyses, the highest monoclinic phase before aging was observed in group Gr (12.6%), and after aging in group Gr-Ag (51.2%).

Conclusion: Grinding and polishing increased the flexural strength, while glazing did not exhibit any significant effect on this parameter.  Furthermore, aging did not adversely affect flexural strength.

Objectives: Some small defects may remain in the impression after making a two-step putty-light body impression. The aim of this study was to evaluate and compare the dimensional accuracy of 2-step and relined 2-step (3-step) putty-light body impressions.

Materials and Methods: In this in vitro study, 30 impressions were made with putty, light body, and extra-light body addition silicone materials using the 2-step and 3-step impression techniques (N=15). An epoxy resin master model was made duplicating a maxillary typodont with left first premolar and first molar teeth prepared with a shoulder finish line and truncated pyramidal-shaped indices in the mid-palate and third molar sites. In addition to creating a reference digital model by scanning the master model, 30 master casts were scanned to produce digital models. The anteroposterior (AP) and cross-sectional (CS) dimensional accuracy of the models were compared with the master model using linear measurements. Moreover, tooth size measurements were made and compared using the root mean square (RMS). Two-sample t-test was applied to analyze the data (α=0.05).

Results: The mean AP and RMS differences between the two study groups were not significant (P>0.05). However, the CS difference between the two groups was significant (P<0.001), and the 3-step impression technique showed smaller discrepancies in comparison to the master model.

Conclusion: There was no significant difference in accuracy of the two techniques for single-unit and multiple-unit preparations. The 3-step impression technique had a higher CS dimensional accuracy.

Objectives: This study aimed to evaluate the shear bond strength of ceramic brackets bonded to the enamel surface using Vertise Flow, with or without the application of phosphoric acid.

Materials and Methods: Forty-five extracted human premolar teeth were randomly assigned to three groups (N=15) based on the adhesive used for bonding: 1) Transbond XT, etch, and bond; 2) Vertise Flow; 3) Etch and Vertise Flow. After a 500-round thermocycling procedure, the shear bond strength was measured using a universal testing machine. The samples were then evaluated under a stereomicroscope to determine failure modes, and the Adhesive Remnant Index (ARI) was measured for each group. The data were analyzed with one-way ANOVA and post-hoc Tamhane at a significance level of P<0.05.

Results: The highest shear bond strength values were observed in the Transbond XT (13.5±5.38MPa), acid etch and Vertise Flow (11.2±2.89MPa), and Vertise Flow (6.2±3.16MPa) groups, respectively, in descending order. The Vertise Flow group exhibited a significantly lower shear bond strength value compared to the other two groups, with no significant difference between the latter two.

Conclusion: While all three study groups demonstrated clinically acceptable shear bond strength values, Vertise Flow showed lower values compared to the other two adhesives. The Vertise Flow composite resin system, whether used alone or with acid etching, remains a suitable choice for bonding ceramic brackets, offering the advantage of a simplified bonding procedure.

Objectives: This study aimed to compare the antimicrobial efficacy of saline, 0.5% and 2% Zataria multiflora (Z. multiflora) essential oil, 0.5% and 2% Mentha piperita (M. piperita) essential oil, and 0.2% chlorhexidine (CHX) as root canal irrigants for primary molar teeth.

Materials and Methods: A total of 64 primary molars were used in this in vitro study. The teeth were randomly assigned to six groups (N=10). The root canals were prepared up to file #35, and all teeth were sterilized before contamination with Enterococcus faecalis (E. faecalis; ATCC 29212) suspension. After 48 hours of incubation, the root canals in each group were irrigated with the respective irrigants. Sterile paper points were then used to collect microbial samples from the root canals. A colony counter was used to count the number of colony-forming units (CFUs). Data were analyzed by SPSS version 20 (alpha=0.05).

Results: The colony count was significantly different among the groups (P<0.001), and 2% M. piperita (P=0.009), 0.5% Z. multiflora (P=0.021), and 0.2% CHX (P=0.002) were significantly more effective than saline in elimination of E. faecalis. The ascending order of microbial count after irrigation was as follows: saline > 0.5% M. piperita > 0.2% CHX > 2% M. piperita > 0.5% Z. multiflora.

Conclusion: The current study showed the optimal antibacterial activity of 0.5% Z. multiflora essential oil and 2% M. piperita essential oil against E. faecalis, and indicated their possible efficacy for use as an irrigant for root canal irrigation of primary molars.

Objectives: This preliminary animal study was conducted to assess the effects of chitosan as a novel obturation material for pulpectomized teeth on periapical inflammation, periodontal ligament (PDL) widening, and hard tissue resorption.

Materials and Methods: Forty premolar root canals in two mature dogs were obturated with zinc oxide eugenol (ZOE) and an experimental 3% chitosan paste (n=20 in each group). The teeth were then restored with amalgam. After 28 days, the dogs were sacrificed, and histopathological assessment was performed. The amount of resorbed obturation material, degree of inflammatory response, degree of PDL widening, and the number of bone/cementum/dentin resorption defects were recorded under ×40 and ×200 magnifications. Data were analyzed using the Mann-Whitney U test, one-sample Wilcoxon signed-rank test, and Fisher’s exact test (α=0.05).

Results: Bone, cementum, and dentin resorption were seen in 6, 10, and 1 chitosan-obturated canals and 14, 15, and 0 ZOE-obturated canals, respectively. Only the bone resorption defects were significantly fewer in the chitosan group (P=0.026). Mild, moderate, and severe inflammation were observed in 17, 3, and 0 chitosan-obturated canals, and 7, 9, and 4 ZOE-filled canals, respectively (P=0.004). Mild, moderate, and severe PDL widening were seen around 15, 5, and 0 chitosan-filled canals and 7, 12, and 1 ZOE-filled canals, respectively (P=0.025).

Conclusion: The 3% chitosan was superior to ZOE in terms of causing less inflammation and PDL widening. It also decreased bone resorption and acted similar to ZOE in terms of dentin and cementum resorption.

Objectives: This study aimed to investigate the effect of different reinforcement techniques on the push-out bond strength of fiber posts to over-flared root canals.

Materials and Methods: Forty-eight extracted human single-canal premolars were endodontically treated, over-flared, and randomly divided into four groups (N=12) including SARC: luting with self-adhesive resin cement, DCC: luting with dual-cure core build-up resin composite, CRR: relining root canal walls with bulk-fill resin composite, and DAP: relining fiber post with bulk-fill resin composite. After 24 hours, the roots were sectioned to obtain three cervical, middle, and apical 3mm slices. The push-out test was performed and failure pattern was examined. Kruskal-Wallis and post-hoc Dunn-Bonferroni tests were used for statistical analysis (P<0.05).

Results: In all three regions, the lowest and highest bond strength was found in the SARC and DAP groups, respectively. In the middle region, there was a statistically significant difference between the bond strength of the SARC group and that of the DCC (P=0.044), CRR (P=0.021), and DAP (P<0.001) groups. There was no significant difference in the apical region. The lowest bond strength was observed in the apical region, and the highest was related to the cervical region. Adhesive failure was the most common failure pattern in all groups.

Conclusion: Based on our results DCC, CRR and DAP methods increased bond strength in the middle and cervical sections of over-flared root regions. Considering that DCC is the easiest and most practical method, we propose that CRR and DAP can be replaced with this method in clinical procedures.

Objectives: Porcelain chipping and delamination are among the shortcomings of all-ceramic restorations. This study aimed to assess the effect of laser irradiation and sandblasting on shear bond strength (SBS) of zirconia to veneering porcelain.

Materials and Methods: In this in vitro, experimental study, 60 zirconia blocks were randomly divided into three groups (n=20) for surface treatment with Er:YAG laser, sandblasting, and no surface treatment (control). Each group was randomly divided into two subgroups (n=10) for porcelain application by the layering or the pressing technique. The surface roughness, SBS, and failure mode were determined and analyzed using two-way ANOVA, Tukey’s HSD test, Chi-square test, and Pearson’s correlation test (alpha=0.05).

Results: The mean SBS was 8.16±3.66 MPa, 9.32±2.7 MPa, and 11.85±3.06 MPa in the control, laser, and sandblasting groups, respectively. The SBS was significantly different among the three groups (P=0.002). The failure mode of the three groups was not significantly different (P>0.05). The sandblasted group showed significantly higher surface roughness than the control and laser groups (P<0.001).

Conclusion: Sandblasting yielded higher SBS particularly when the porcelain was applied by the layering technique. Although laser irradiation increased the SBS, the difference with the control group was not statistically significant.

Objectives: The use of fiber posts in endodontically treated primary maxillary central incisors improves the retention of composite resin restorations. The purpose of this study was to evaluate the effect of 4 different luting cements on fracture resistance of primary maxillary central incisors with fiber posts.

Materials and Methods: In this in vitro study, 40 primary maxillary central incisors were endodontically treated and obturated with Metapex. They were then randomly divided into four groups (n=10) for cementation of fiber posts with GC Fuji I glass ionomer luting cement, Panavia F2.0 dual-cure luting cement, Panavia SA Luting Plus cement (self-adhesive), and TotalCem self-adhesive cement. After 1000 thermal cycles, the fracture resistance was measured. Data were statistically analyzed using ANOVA (alpha=0.05).

Results: The mean fracture resistance was 267.07±130.01N in TotalCem, 257.27±102.56N in Panavia F2.0 dual-cure cement, 227.82±110.40N in Panavia SA Luting Plus self-adhesive cement, and 220.89±59.96N in GC Fuji I glass ionomer group. There was no statistically significant difference in fracture resistance among the four groups (P=0.714).  

Conclusion: Type of luting cement had no significant effect on fracture resistance of primary maxillary central incisors with fiber posts. Nonetheless, TotalCem yielded the highest fracture resistance. Considering its self-adhesive property and easy workability, it can be a good option for cementation of fiber posts in endodontically treated primary central incisors.

Objectives: This study assessed the effects of blue and Er:YAG lasers, fluoride varnish, and their combination on microhardness, and calcium and phosphorus content of demineralized enamel.

Materials and Methods: The primary Vickers microhardness of 28 third molars was measured and their enamel calcium and phosphorous content was quantified by energy-dispersive X-ray spectroscopy. They were then randomly assigned to five groups of 5% sodium fluoride (NaF) varnish, 445nm blue laser, Er:YAG laser, 5% NaF + 445nm blue laser, and 5% NaF + Er:YAG laser. The teeth then underwent pH-cycling to induce caries-like lesions. The surface microhardness of the teeth and the calcium and phosphorous content of demineralized enamel were measured again. Data were analyzed by one-way ANOVA and Tukey’s test (alpha=0.05).

Results: NaF, NaF-diode laser, and NaF-Er:YAG laser groups experienced a significant increase in microhardness of demineralized enamel close to the baseline value (P<0.05). The efficacy of NaF-blue laser and NaF-Er:YAG laser was higher than NaF . In blue and Er:YAG laser groups, the mean final microhardness was significantly lower than the baseline microhardness. The percentage of phosphorus in all groups was similar to that of sound enamel. The percentage of calcium in NaF group was significantly lower than that of sound enamel and all other groups. The calcium content in other groups was similar to that of sound enamel.

Conclusion: Fluoride varnish had a synergistic effect with Er:YAG and blue lasers to increase the demineralized enamel microhardness; blue and Er:YAG lasers alone were less effective.

Objectives: Compare the tensile strength and rupture elongation of room temperature vulcanizing silicone (RTV), heat temperature vulcanizing silicone (HTV) and 3% SiO2 reinforced RTV and HTV following disinfection with various agents.

Materials and Methods: According to ASTM D412, 384 samples were fabricated using HTV, RTV, RTV and HTV reinforced with 3% SiO2 nanoparticles. The control group received no disinfection treatment, while the other samples were disinfected for 10 minutes using neutral soap, 4% chlorhexidine, and ozone water, three times a day for 60 days. Additionally, accelerated aging was carried out for 252,504,1008 hours. Tensile strength and rupture elongation were assessed using a universal testing machine at 500 mm/min speed, and the mean values were analyzed using two-way ANOVA and Tukey HSD test (P<0.05).

Results: The mean value of tensile strength of RTV (2.96 ± 0.41), 3%SiO2 RTV (3.26 ±0.33), HTV (3.30 ±0.36),3% SiO2 HTV (4.07 ±0.85) MPa which was statistically significant for control, neutral soap and 4% chlorhexidine at 252,504 ,1008 hours of aging. (P <0.05). The percentage of elongation of RTV (545 ±29.2),3%SiO2 RTV (617 ±30.5), HTV (735 ±48.7),3% SiO2 HTV (801 ±55.7) which was statically significant for control, neutral soap, 4% chlorhexidine and Ozone water for 252, 504 ,1008 hours of aging. (P <0.05).

Conclusion: The HTV silicone showed more tensile strength and rupture elongation compared to HTV, RTV and RTV silicones reinforced with 3% SiO2 nanoparticles. Ozone water disinfection had least effect on tensile strength and rupture elongation of maxillo-facial silicone compared to other disinfectant.

Objectives: This study assessed the efficacy of different combinations of oxalic acid, 35% hydrogen peroxide, and 5.25% sodium hypochlorite (NaOCl) for bleaching of tooth discolorations caused by hemoglobin.

Materials and Methods: In this in vitro study, 40 sound extracted human premolars were disinfected and decoronated. Their primary color parameters were measured (T1). The teeth were then centrifuged with human blood for 3 days, rinsed, polished, and their color parameters were measured again (T2). They were randomly divided into 4 groups (N=10) and treated as follows: Group A: in-office bleaching with Pola-Office Plus followed by 30 seconds of light-curing, group B: 0.24 M oxalic acid for 5 minutes followed by in-office bleaching, group C: 5.25% NaOCl for 5 minutes followed by in-office bleaching, and group D: 0.24 M oxalic acid (5 minutes) followed by 5.25% NaOCl (5 minutes) and subsequent application of in-office bleaching gel. The color parameters of the teeth were measured again (T3). Data were analyzed by one-way ANOVA and paired sample t-test (alpha=0.05).

Results: T2-T3 ∆E in groups B and D was significantly higher than that in group A (P<0.05); the difference between groups B and D was not significant. The mean ∆E and ∆L in group C were not significantly different from those in group A (P>0.05). ∆L significantly and equally increased in groups B and D after bleaching.

Conclusion: Application of oxalic acid followed by in-office bleaching gel is more effective than the bleaching gel alone for correction of tooth discolorations caused by hemoglobin.

Objectives: This study evaluated the effect of a flipped oral health educational program for primary healthcare providers (PHCPs) on their knowledge, attitude, and practice.

Materials and Methods: This field trial was conducted on PHCPs (N=118; 61 cases and 57 controls) in District Health Centers (DHCs) of Tehran, Iran in 2012. The participants filled out a self-report questionnaire with questions on knowledge (N=34), attitude (N=8), and oral health practice (N=14). The intervention included an educational booklet delivered to the staff followed by a brief educational session using the flipped approach and a reminder pamphlet after 1 month. After 4 months, the questionnaire was completed again by the participants. Statistical analysis included paired sample t-test, ANCOVA, and linear and logistic regression.

Results: Most participants were females (N=114), and the mean age was 37±8 years. The scores of the three domains of knowledge and also the total knowledge score, the attitude score, and the practice score significantly improved in the intervention group compared to the control group (P<0.001). Knowledge about the oral health of children (P=0.001) and the total knowledge score (P<0.05) significantly increased in the control group, but the increase in other domains was not statistically significant (P>0.05).

Conclusion: The oral health knowledge of PHCPs was insufficient, and their practice and attitude were not desirable. The oral health educational program with the flipped approach had a positive impact on the PHCPs’ knowledge, attitude and practice, and may be utilized in the academic curriculum or continuing medical education (CME) courses.

Objectives: We aimed to evaluate ceramic-alloy interface and emphasize the alteration of alloy microstructure after ceramic layering.

Materials and Methods: Thirty-two discs made from a ceramic-alloy combination of pre-sintered cobalt-chromium (CoCr), cast CoCr, cast nickel-chromium (NiCr), or pre-sintered zirconia were prepared with eight discs in each group. Four specimens were examined as manufactured and four were ceramic-layered. Scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-Ray diffractometer (XRD), and an atomic force microscope were used for analysis. Non-layered specimens received ceramic fire-heating without adding any ceramic. Alloy microstructure was compared before and after ceramic veneering or heating within the same group. Mean differences in grain size and surface roughness were compared among groups. P<0.05 was considered significant.

Results: SEM showed a close bonding interface between alloys and ceramics. EDX demonstrated differences compared to the manufacturer’s composition. Ceramic-layering reduced grain size for both milled alloys (P<0.05), whereas grain size increased in cast groups (P=0.011). Heat treatment did the same for the CoCr groups (P=0.013). Ceramic veneering increased the surface roughness of the cast CoCr (Gi) (P=0.029) and NiCr (Wi) (P=0.005) groups, whereas zirconia roughness average (Ra) showed a slight decrease (P=0.282). XRD showed no differences among zirconia, NiCr, and milled CoCr groups before and after veneering. Crystallite size differed between monoclinic and tetragonal phases in zirconia.

Conclusion: The study highlights that ceramic-layering induces significant microstructural changes in alloys, enhancing bonding potential and mechanical stability. Pre-sintered materials show a fine homogeneous surface, optimizing ceramic adherence and potentially improving clinical outcomes.

Objective the main purpose of this study was to compare the effects of casein phosphopeptide amorphous calcium phosphate fluride (CPP-ACPF) and tricalcium phosphate on artificial early enamel carious lesions.

Materials and Methods 45 sound extracted premolars were divided, and placed in the demineralization solution (pH=4.5) for 96 hours, divided randomly in 3 groups (TCP-MI paste Plus-Control) then they were exposed with the treating materials for 5 minutes once a day in 30 days. After mounting in the resin blocks and polishing, they were subjected to micro hardness test in 3 different depths from the surface of enamel. Data were analyzed using ANOVA test. The significance was set at 0.05.

Results the average volume percent mineral (VPM) showed that in 30, 60 and 90 µm depths there was a significant difference (P Value<0.0001) between both TCP and CPP-ACPF and control group. In 30 µm depth, CPP-ACPF was more effective (P Value<0.0001) than TCP. In 60 and 90 µm depths there was no significant difference between the two groups.

Conclusion In this study we concluded that both CPP-ACPF and TCP have a significant effect on the remineralization of white spot lesions of dental enamel.

Objectives: Surface roughness is one of the important properties of composite restorations. Different polishing systems are used to provide an appropriate composite restoration surface. The aim of this study was to evaluate the effects of Sof-Lex, Eve, and Astropol polishing systems on composite resin surface roughness after aging.

Materials and Methods: In this in vitro study, 36 composite discs (8×2mm) were fabricated. The specimens were randomly divided into three groups (N=12) for polishing with (I) Sof-Lex (3M ESPE), (II) Eve (Ernst Vetter GmbH), and (III) Astropol (Ivoclar/Vivadent) polishing systems. The specimens were then subjected to thermocycling. Surface roughness of the specimens was measured before and after polishing, and after thermocycling by a contact profilometer. Repeated Measures ANOVA was used to analyze the data (α=0.05).

Results: Although Astropol showed slightly higher surface roughness in comparison to Sof-Lex and Eve, the level of surface roughness before and after polishing and after aging was not significantly different among the three polishing systems (P=0.704).

Conclusion: Within the limitations of this in vitro study, Sof-Lex, Eve, and Astropol showed similar acceptable results with regard to composite resin surface roughness.

Objectives: The goal of this investigation was to see how a dentin pretreatment with 5% DMSO affected the microtensile bond strength (μTBS) of universal adhesives.

Materials and Methods: In terms of adhesive kind and etching procedure, 32 healthy third human molars were randomly separated into eight groups. Three universal adhesives with etch-and-rinse and self-etch strategies (G-Premio Bond: GPB.ER/SE, All-Bond Universal: ABU.ER/SE, Prime & Bond Elect: PBE.ER/SE), one two-stage self-etch adhesive (Clearfil SE Bond: CSB), and one two-stage etch-and-rinse adhesive (Adper Single Bond 2: ASB) were employed in with and without DMSO modes (group/N=16). Dentin pretreatment was conducted with 50 μl of 5% DMSO, followed by the use of an adhesive. The μTBS of samples was tested. The influence of adhesive type and DMSO application on bond strength was evaluated using a two-way analysis of variance (ANOVA) (=0.05).

Results: The dentin-adhesive μTBS was significantly affected by DMSO administration (P=0.003), type of adhesive (P=0.001), and the combination of DMSO application and type of adhesive (P=0.027). In the DMSO application mode, the average bond strength of universal adhesives with etch and rinse mode was significantly higher than in the non-application mode, but in the self-etch technique, there was no significant difference pattern between DMSO applications and non-application modes in terms of adhesive bond strength.

Conclusion: The use of DMSO in an etch-and-rinse technique can dramatically enhance the universal adhesive-dentin μTBS and has promise benefits for clinicians in terms of enhancing dentin bond performance.

Conventional obturator prostheses might cause dissatisfaction in patients with hard or soft palate defects due to inadequate retention and function during speech, mastication, and swallowing. Thus, surgical reconstruction and implant-supported obturators are considered as alternative treatments for these patients.

This case-report study describes the prosthetic reconstruction of an 88-year-old patient suffering from a hard palate defect after surgical resection of verrucous carcinoma in the left side of the hard palate. Fifteen months after radiotherapy, two implants were placed in the right side of the remaining ridge, in the second and third molar region. After the implant healing period, the implant-supported obturator prosthesis was fabricated. The patient was satisfied with the esthetics and function of the obturator at the 12-month recall visit and radiographs showed normal healing and no bone loss around the implants.

Restoring severely damaged teeth has always been challenging when the remaining crown structure is limited, and retention might be necessary from the root canal using intracanal posts. However, the real challenge is when the root canal walls are also weak, and there is a high risk of vertical root fracture due to the wedging forces of a rigid post. This case report presents a tooth with flared root canal walls successfully restored with a newly introduced polymer made of polyether ether ketone (PEEK) (BioHPPfor2press,Bredent,UK) with one-year follow-up. Regarding its close elastic modulus to dentin, the ability to bond to tooth structure, shock-absorbing ability, and therefore favorable stress distribution, using this material for an intracanal post may minimize the risk of fractures commonly observed with cast metal posts. It combines good fitness of cast posts with low modulus of elasticity and optical properties of prefabricated fiber posts.

Hypodontia is the most common dental developmental disorder. Several underlying mechanisms have been proposed to be involved in its pathogenesis. Occurrence of hypodontia as an isolated trait due to genetic mutations has also been reported. Hypodontia most commonly involves the mandibular premolars, maxillary lateral incisors and second premolars. However, hypodontia of permanent second molars is a rare occurrence. To the best of the author’s knowledge, only two studies on orthodontic patients have reported hypodontia of permanent second molars in Iran.

This case report describes non-syndromic bilateral missing of permanent mandibular second molars in a 10-year-old child. Clinical examination revealed no systemic underlying condition, and no clinical evidence of any syndrome, or hereditary or familial pattern. Due to the potential impact of hypodontia on the function of dentition, prompt management of hypodontia is imperative. Furthermore, due to the possible mutations associated with hypodontia, additional screening for cancer susceptibility may be recommended.

Porcelain laminate veneers (PLV) offer a conservative aesthetic solution for interdental space closure. However, space is typically not distributed symmetrically, and the mesiodistal width of the restored teeth may increase unless multiple teeth are prepared for conventional PLV to maintain appropriate individual tooth proportion. Ceramic fragments can be suggested to close the space without modifying tooth size and dental proportion. This article presents two cases where interdental gaps were closed using lingually placed porcelain laminate (LPPL). All stages of the restorative procedures, including treatment planning, temporization, tooth preparation, and cementation of these delicate restorations, are detailed. Based on the results of these clinical reports, we regard the use of LPPL as a successful treatment option in selected cases, as evidenced by 2- and 6-year follow-ups. The Modified United State Public Health Criteria is reported.

Ectopic eruption of molars occurs more frequently in developing permanent dentition, and requires immediate intervention. Herein, two cases are discussed with ectopic eruption of permanent maxillary first molars which were diagnosed and managed conservatively using a modified Humphrey's appliance, named the NR’s appliance. The appliance was fabricated by band adaptation and using wire components of a 21-gauge stainless-steel wire. Also, the Nance palatal arch was used as the anchorage unit. The molars were uprighted and distalized within 3 months. Early diagnosis and prompt treatment could result in prevention of malocclusion in the early mixed dentition period.