Frontiers in Dentistry

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.  

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.