Frontiers in Dentistry最新文献

Objectives: The main purpose of this study was to compare the remineralizing effects of casein phosphopeptide amorphous calcium phosphate fluoride (CPP-ACPF) and tricalcium phosphate (TCP) on artificially induced enamel white spot lesions (WSLs). Materials and Methods: In this in vitro study, 45 sound extracted premolars were immersed in a demineralizing solution (pH=4.5) for 96 hours, and were randomly divided into 3 groups of TCP, MI Paste Plus, and control. They were exposed to the remineralizing agents for 5 minutes once a day for 30 days. After mounting the teeth in resin blocks and polishing, they underwent a microhardness test at 3 different depths from the enamel surface. Data were analyzed by Prism software, two-way ANOVA, and Tukey's test (α=0.05). Results: The volume percentage of mineral content (VPM) was significantly different among the three groups at 30-, 60- and 90µm depths (P<0.0001). At 30µm depth, CPP-ACPF was significantly more effective than TCP (P<0.0001). At 60- and 90µm depths, there was no significant difference between CPP-ACPF and TCP (P>0.05). Conclusion: Both CPP-ACPF and TCP had significant efficacy for remineralization of artificially induced enamel WSLs under in vitro conditions.

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.

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.

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.

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: 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 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.