Journal of Clinical and Experimental Dentistry最新文献

Background: Guided bone regeneration (GBR) requires resorbable implants that balance corrosion resistance and biocompatibility. Magnesium (Mg) is a promising candidate, but its rapid degradation necessitates protective coatings. This study develops and characterizes a strontium-zinc (Sr-Zn) conversion coating on Mg plates for resorbable tack screws, evaluating its corrosion resistance, surface properties, and biocompatibility.

Material and methods: Mg plates (20×15×2 mm) were etched with HCl, coated with Sr-Zn via immersion (30 min, pH 3-5), and characterized using SEM, EDX, and FTIR. Corrosion resistance was assessed via potentiodynamic polarization in simulated body fluid (SBF). Biocompatibility was evaluated using MG63 osteoblast cultures, with statistical comparison (Student's t-test, p < 0.05) between coated (Group A) and uncoated (Group B) plates.

Results: SEM revealed a dense, fibrous coating with interconnected pores, enhancing cell adhesion. EDX confirmed Zn (46.6 wt%) and Sr (3.7 wt%) incorporation. FTIR identified hydroxyl/carbonyl groups and metal-oxygen bonds. The coating improved corrosion resistance compared to bare Mg plates. In vitro cell culture assays demonstrated that Sr-Zn conversion-coated Mg plates (Group A) showed comparable cell viability to bare Mg plates (Group B) at all tested time points. Peak cell viability was recorded at 24 hours, with Group A achieving 92.66% and Group B reaching 91% (p = 0.238). This statistically non-significant difference suggests successful biocompatibility of the Sr-Zn coating. The enhanced biocompatibility observed is likely attributed to the coating's improved corrosion resistance.

Conclusions: The Sr-Zn coating improved Mg's corrosion resistance while maintaining osteoblast viability, supporting its potential for resorbable GBR tack screws. Key words:Guided bone regeneration, Magnesium implants, Strontium-zinc coating, Corrosion resistance, Biocompatibility, Resorbable screws.

Background: Proper finishing and polishing are crucial for reducing surface roughness and eliminating the incompletely polymerized oxygen-inhibited layer. This study compared surface characteristics - specifically water contact angle, surface roughness, and morphology of three nanohybrid composite resins polished with two different multi-step polishing systems.

Material and methods: We evaluated Filtek Z250 (3M), Tetric N-Ceram (Ivoclar), and Spectra Smart (Dentsply), all in shade A2. Thirty-nine discs per resin (9 mm diameter × 2 mm thickness) were fabricated, stored in distilled water at 37°C for 24 hours, and pre-polished with silicon carbide paper (600, 1000, and 1200 grit). Final polishing employed two systems: the 3-step Astropol system (Ivoclar) and the 2-step ShapeGuard system (Diatech), with each system tested through six reuse cycles (three samples per resin per cycle). Surface analysis included water contact angle measurement, profilometry, scanning electron microscopy (SEM), and energy-dispersive X-ray spectroscopy (EDS).

Results: The Astropol system demonstrated significantly greater hydrophobicity (107.6° ± 10.9°) than ShapeGuard (99.1° ± 9.0°). Among the tested resins, Filtek Z250 polished with Astropol showed the lowest surface roughness (0.27 ± 0.11 µm), while Spectra Smart polished with ShapeGuard showed the highest (0.78 ± 0.20 µm). Polishing system reuse showed no significant effects on results. SEM revealed no noTable morphological changes, and EDS confirmed consistently high SiO2 content across all resins.

Conclusions: Both polishing system and resin composition significantly influence surface characteristics. Filtek Z250 performed optimally with both polishing systems. Further research should investigate the long-term effects of polishing system reuse. Key words:Nanohybrid resins, polishing systems, surface roughness, contact angle, SEM.

Background: The replacement of missing teeth with implants is a frequent procedure in dental practice, and is usually associated with high implant survival rates. Peri-implant diseases are very common, however. It is therefore essential for clinicians to periodically examine and evaluate implant-supported restorations. The main objective of the present study was to evaluate the level of knowledge about peri-implant diseases and determine the possible associations with demographic variables in fifth year dental students of the University of Barcelona (Spain).

Material and methods: A cross-sectional study of the knowledge about peri-implant diseases was carried out using a survey administered to the fifth year dental students of the University of Barcelona. Descriptive and bivariate analyses using the Student t-test and Pearson correlation coefficient were made. The significance level was set at p < 0.05.

Results: Eighty-three students were included in the study. A mean of 8.7 points (correct answers) were recorded out of a total of 15 possible points. Good student knowledge was observed in relation to prevention and risk factors. No significant associations were observed between the number of correct answers and the different variables studied. Almost all the students (95.2%) underscored the need for further training in peri-implant diseases.

Conclusions: Fifth year students have average level knowledge about peri-implant diseases, with good mastery of prevention and risk factors. There is a general perception that knowledge about prevention and risk factors and the treatment of peri-implant diseases is not enough. In addition, the students are aware of their shortcomings and recognize the need for further training in this field. Key words:Dental education, peri-implant diseases, dental implant, knowledge, dental students, dental education.

Background: Glandular Odontogenic Cyst (GOC) is a rare benign lesion with unique histological features, and more aggressive growth pattern compared to other odontogenic cysts. GOC typically presents as an asymptomatic, slow-growing swelling, predominantly affecting middle-aged males and often localized in the anterior mandible. This report details three cases of GOC affecting the maxilla.

Case report: Case 1 presented a GOC mimicking a residual cyst in the maxilla. Case 2 involved a GOC located within the maxillary sinus. Case 3 showed a multilocular radiolucent GOC in the anterior maxilla. All cases were treated by surgery, and the diagnosis was confirmed through microscopic examination.

Conclusions: Clinicians should consider GOC when evaluating unilocular or multilocular lesions in the maxilla. Key words:Odontogenic cyst, Jaws, Maxilla, Glandular odontogenic cyst.

Background: The aim of this study is to understand the perceptions of young non-dental professionals and orthodontists on the aesthetics of facial profile.

Material and methods: Perceptions were assessed using seven types of profile for both sexes, which represented different relations of the maxilla and mandible. In total, 50 young laypeople and 20 orthodontists were randomly selected to evaluate the aesthetics of each profile using numbers 1 to 10 to rank them in order of attractiveness. Aesthetics score was considered as a quantitative variable and comparison between groups was done with an ANOVA, and age and orthodontic treatment history of the evaluators from the young non-dental population was used as covariates to assess its possible effect.

Results: The following female profiles were rated as most aesthetic: protruding jaw (p<.001; R2:21.9%) and retruded jaw (p<.001; R2:22.1%). The following male profiles were rated as most aesthetic: retruded maxilla (p=.001; R2:14.7%), bi-protruding maxilla and mandible (p<.001; R2: 54.4%) and straight maxilla and mandible (p<.05; R2:8.7%). Based on the sex of the evaluator, only significant differences were observed in these two male profiles. The straight profile showed significant differences (p<.10) with a moderate effect (4.3%), and the bi-retruded profile (p<.05) also had a moderate effect (8.5%); these were rated higher by men. Insufficient statistical evidence was found to admit that a history of orthodontic treatment influences aesthetic perception of male or female profiles. For all the variables, evaluators from the young population scored higher than orthodontists for both male and female profiles.

Conclusions: The straight profile was considered more aesthetic for both sexes. Differences in aesthetic perception depending on sex and previous clinical history of orthodontic treatment were minimal. It can be concluded that the young lay population is less demanding in its evaluations than orthodontists. Key words:Orthodontics, facial profile, aesthetic, aesthetic perception.

Background: Understanding the cephalometric factors that affect the mentolabial angle and lower lip eversion is essential for orthodontics. The objective was to evaluate the influence of various skeletal and dentoalveolar cephalometric features associated with the mentolabial angle and lower lip eversion in young adults.

Material and methods: This cross-sectional study assessed lateral head radiographs of individuals between the ages of 15 and 40 years. Two trained and calibrated evaluators performed angular and linear cephalometric measurements utilizing BlueSky Plan 4 software. The variables evaluated in this study included the presence of the mentolabial angle, labial eversion, overjet, and the position and inclination of the lower central incisors (measured by I-NB, I.NB, IMPA) as well as the upper central incisors (measured by I-NA, I.NA, UIPP). Additionally, we assessed the sagittal positions of the maxilla and mandible using SNA and SNB measurements, along with the sagittal and vertical skeletal relationships determined by the ANB and FMA angles. We applied multiple linear and binary logistic regression tests for statistical analysis (p<0.05).

Results: 138 radiographs were evaluated (73 females and 65 males). The mentolabial angle is, on average, 7.68° greater in women than men (p=0.001). An increase in the IMPA and overjet decreases 0.40° (p=0.012) and 2.02° (p=0.003) in the mentolabial angle, respectively. Likewise, females are 82% less likely to experience lip eversion than males (exp B = 0.18, 0.05 to 0.60 CI 95%; p=0.006). Furthermore, for each degree increase in lower incisor inclination (I. NB) or overjet, the risk of developing lip eversion increases by 1.17 times (1.02 - 1.34 CI to 95%, p=0.023) and 1.85 times (1.23 - 2.78 CI to 95%, p=0.003), respectively.

Conclusions: The inclination of the lower incisors and the overjet primarily influences the mento-labial angle. Women tend to have a greater mento labial angle, meaning it is more retrusive, compared to men. Additionally, the likelihood of lip eversion is higher in males. For each degree of increased lower incisor inclination or overjet, the risk of developing lip eversion also rises. Key words:Cephalometry, Chin, Dental Esthetics, Lip.

Background: Squamous cell carcinoma (SCC) of the head and neck is the main histological type and the sixth most common cancer in the world. However, tumors other than squamous cell carcinoma can affect the oral cavity, such as salivary gland carcinomas, lymphomas and sarcomas.

Material and methods: A quantitative, retrospective, observational and cross-sectional study, in which 395 medical records of patients diagnosed/treated with non-SCC head and neck tumors from 2000 to 2020 at the Haroldo Juaçaba Hospital/Ceará Cancer Institute (HHJ/ICC) were analyzed. The data was compared using Pearson's chi-square test or Fisher's exact test, Kaplan-Meier overall survival curves were constructed and the Mantel-Cox log-rank test was used.

Results: Salivary gland tumors (1st = Adenoid Cystic Carcinoma), followed by sarcomas (1st = Kaposi's Sarcoma) and lymphoproliferative tumors (1st = Diffuse Large B-Cell Lymphoma). The majority of the sample were women, with a mean age of 56 and a low level of education. Median overall survival was (95%CI = 57.29-101.71) months, with no difference between the lesion groups (p=0.727). Salivary gland tumors and sarcomas affected significantly younger age groups (p=0.011). Most of the sample was N0 (p=0.006) and multimodal therapy was the preferred choice, especially for salivary gland tumors, sarcomas and melanomas (p<0.001). Schooling (p=0.007) was inversely associated with overall survival and the independent predictor of death was the presence of lymph nodes (p=0.039).

Conclusions: The frequency of non-SCC head and neck tumors is very low. There is no difference between men and women, age is a determining factor in differentiating tumors and lymph node metastasis is the main predictor of survival. In addition, schooling is an important risk factor for mortality in these patients. Key words:Head and Neck Neoplasms, Squamous Cell Carcinoma, Salivary Gland Neoplasms, Survival.

Background: The objective of this study was to determine the esthetic preference of the upper central incisor (UCI) inclination from a smiling profile view in laypeople of Latin American origin.

Material and methods: This descriptive and cross-sectional study used a smiling profile photograph that was digitally modified to generate 7 types of UCI inclinations (+15°, +10°, +5°,0°, -10°, and -15°). Thus, 160 evaluators distributed in 4 groups (40 Peruvians, 39 Mexicans, 40 Brazilians and 41 Colombians) assessed the images using a visual analog scale. Kruskal-Wallis and Dunn Bonferroni tests were applied for multiple comparisons of ratings between groups (p<0.05).

Results: The general sample of evaluators of the four nationalities considered -5° the most attractive slant and 0° the second most attractive slant, although a significant difference was found in the intensity of preference (p<0.001). Further, Peruvians rated the intensity of preference being -5° (Visual analogic scale (VAS) = 80 points) and 0° (VAS = 77 points) the most attractive inclinations, Mexicans rated 0° (VAS = 90 points) and -5°, -10° and 5° (VAS = 80 points) as the most attractive, Brazilians rated the most attractive inclinations at -5° and 0° (both with VAS = 80 points) and Colombians rated the most attractive inclinations at -5°, 0°, 5° and 10° (VAS = 60 points).

Conclusions: Slightly retroclined (-5°) and neutral (0°) inclinations of central incisor were the most preferred by the Latin American individuals. This result should be considered by orthodontists for treatment planning. Key words:Upper central incisors, inclination, esthetic preference, perception.

Background: Nickel-based alloys in fixed orthodontic appliances are susceptible to electrochemical corrosion in the oral environment, releasing ions with cytotoxic and allergenic potential. While previous studies have documented initial nickel release patterns, the longitudinal dynamics of its accumulation across oral biospaces (saliva, biofilm, gingival tissue) and interactions with salivary pH remain poorly characterized. This study investigates nickel accumulation in saliva, oral biofilm, and gingival tissue over 12 months of orthodontic treatment and its association with salivary pH.

Material and methods: This 12-month prospective cohort study enrolled 120 participants undergoing fixed orthodontic treatment. Nickel concentrations were quantified via graphite furnace atomic absorption spectrophotometry in three biospaces at baseline (T0), 6 months (T1), and 9-12 months (T2). Salivary pH was measured concurrently. Statistical analyses included non-parametric longitudinal comparisons, inter-biospace contrasts, Spearman correlations, and multivariate regression modeling to identify predictors of nickel accumulation.

Results: Nickel exhibited distinct spatiotemporal patterns: progressive accumulation in biofilm (0.0008→21.5833 µg/L, p<0.001) versus biphasic kinetics in gingiva and saliva (peaking at T1 then declining). By T2, biofilm concentrations were 1000× higher than other biospaces (p<0.001). Treatment duration was the strongest predictor across all compartments (β=0.56-0.67, p<0.001), with biofilm accumulation additionally modulated by salivary pH (β=0.22, p=0.027) and age (β=-0.19, p=0.041). A time-dependent correlation emerged between salivary pH and biofilm nickel (T0: r=0.17, p=0.112; T2: r=0.41, p=0.008), suggesting pH-microbiome interactions.

Conclusions: Oral biofilm serves as the dominant long-term nickel reservoir during orthodontic treatment, with accumulation dynamics influenced by treatment duration, pH, and age. The pH-dependent biofilm-metal interaction highlights its potential as a biomarker for exposure monitoring and a target for preventive strategies. These findings support the development of pH-modulating oral care protocols and corrosion-resistant orthodontic materials to mitigate nickel exposure risks. Key words:Nickel, saliva, Spectrophotometry, Atomic, Orthodontic Appliances, Hydrogen-Ion Concentration.

Background: This study compared the impact of varying irrigating solution volumes and two ultrasonic tips on removing hard tissue debris (HTD) during passive ultrasonic irrigation (PUI) in mesial roots of mandibular molars.

Material and methods: Sixty roots were instrumented using WaveOne Gold 35/.06 divided into 5 groups (n=12): Irrisonic 6 mL (IR6), Irrisonic 30 mL (IR30), Irrisonic Power 6 mL (IRP6), Irrisonic Power 30 mL (IRP30), and a control group with conventional irrigation. Microcomputed Tomography was used to measure HTD removal. Statistical analysis used ANOVA, Tukey, and t-Student tests (α = 5%).

Results: Significant differences were observed in HTD removal between the IR30, IRP6, IRP30 groups, and the control group (P < 0.0001), while no statistical significance was found between IR6 and the control group (P > 0.05). A statistical difference was observed between IR30 and IR6 (P < 0.05). IR30 achieved the highest debris removal rate (87.63%), while IR6 showed the lowest (80.16%). Significant differences were observed between experimental and control groups (P < 0.05), except for IR6 (P > 0.05).

Conclusions: A larger volume of irrigating solution (30 mL compared to 6 mL) during the PUI protocol resulted in greater removal of HTD. Additionally, the Irrisonic Power tip did not significantly enhance HTD removal. Key words:Endodontics, Passive Ultrasonic Irrigation, Root Canal Irrigant, Ultrasonic tip, X-ray microtomography.