مجله تحقیق در علوم دندانپزشکی
سال بیست و سوم شماره 1 (پیاپی 87، بهار 1405)

Radiographic imaging is one of the main pillars of diagnosis in dentistry, and cone-beam computed tomography (CBCT) has widespread application due to its high accuracy. However, exposure to ionizing radiation has consistently raised concerns regarding biological and cellular effects. Therefore, identifying strategies to reduce radiation-induced damage is of particular importance. This study was conducted to investigate the effect of curcumin on nuclear changes and the repair process of buccal mucosal cells following CBCT imaging.

This clinical trial was conducted in 2024 on 76 patients referred to the Department of Oral and Maxillofacial Radiology at Islamic Azad University. Participants were divided into four groups: the first group received CBCT only; the second group consumed curcumin supplementation (600 mg per day) before CBCT; the third group consumed curcumin after CBCT; and the fourth group consumed curcumin both before and after CBCT. Buccal mucosal cell sampling was performed before imaging, immediately after exposure, and ten days later, and nuclear changes were evaluated using microscopy.(P<0.001)

No statistically significant differences were observed among the groups in the first and second sampling stages . However, in the third sampling stage, the micronucleus, karyolysis, and broken egg indices were significantly lower in the curcumin-receiving groups, particularly in the groups consuming curcumin after CBCT and both before and after CBCT, compared with the control group . .(P<0.001)

Curcumin consumption can help reduce CBCT radiation–induced nuclear damage and may play an effective protective role against the harmful effects of X-ray radiation.

White spot lesions are common complications of fixed orthodontic treatment. This study aimed to investigate the association between salivary secretor phenotype and the incidence or progression of these lesions.

This observational follow-up study was conducted on 90 candidates for fixed orthodontics. Demographic data and blood groups were recorded, and unstimulated saliva samples were collected. Secretor status was determined using the agglutination inhibition test. WSLs were evaluated based on ICDAS criteria and standardized photography immediately and three months after bonding. Statistical analysis, including comparative tests (e.g., chi2, Wilcoxon, and Mann–Whitney) and binary logistic regression adjusted for confounding variables, was performed using SPSS v.27.

Among 90 patients, 66 (73.3%) were secretors. The overall frequency of WSLs increased from 5.6% at baseline to 32.2% at the three-month follow-up (p < 0.001). By the end of the third month, the incidence or progression of lesions was significantly higher in non-secretors (58.3%) compared to secretors (22.7%, p < 0.05). Logistic regression identified secretor status as a significant predictor for WSLs (p = 0.009), with secretors having a 70% lower risk (OR = 0.3). Stratified analysis showed varying impacts across different blood groups.

Salivary non-secretor status is a significant risk factor for the development of white spot lesions during early orthodontic treatment. Identifying this phenotype can facilitate targeted preventive strategies for high-risk patients.

The strength and durability of porcelain veneers on teeth are of great importance. The purpose of this study was to evaluate the effect of different incisal reduction designs on the fracture resistance of ceramic laminate veneers.

This experimental in vitro study was conducted on 30 human maxillary central incisors with similar dimensions. The samples were randomly divided into five groups of six specimens each. Initially, all samples were debrided and mounted in acrylic resin. All preparations had a butt-joint incisal finish line. Impressions were taken, and ceramic laminate veneers were fabricated in the laboratory and subsequently cemented onto the specimens. The samples were then subjected to fracture resistance testing using a universal testing machine (UTM). Veneers were loaded at a 90° angle to the lingual surface until fracture occurred. The obtained data were analyzed using one-way analysis of variance (ANOVA) and LSD post hoc tests. Statistical analysis was performed using SPSS software version 25.

The results showed that the fracture resistance of ceramic laminate veneers with 1-mm incisal reduction (312.5 ± 19.24 N) was significantly higher than that of veneers with 3-mm incisal reduction (236.5 ± 16.88).  P<0.001 In addition, veneers bonded to enamel (1-mm reduction) exhibited significantly higher fracture resistance compared to veneers bonded to dentin (3-mm reduction). The results also indicated that veneer thickness (1 mm versus 3 mm) had no significant effect on the fracture resistance of ceramic laminate veneers. (P=0.196)

Incisal edge reduction has a significant effect on the fracture resistance of ceramic laminate veneers, regardless of veneer thickness. Increasing veneer thickness does not significantly enhance fracture resistance.

The aim of this study was to compare the effect of two bleaching agent, hydrogen peroxide 40% and carbamide peroxide 20% on the surface roughness of two types of composite resins: microhybrid and nanohybrid .

In this experimental study, 60 nanohybrid and microhybrid composite disks with a diameter of 10 mm and a thickness of 2 mm were prepared. After measuring the initial surface roughness, the specimens in each composites group  were divided into three subgroups: control, 20% carbamide peroxide and 40% hydrogen peroxide(n=10).In the control subgroup, the specimens were stored in distilled water for 14 days ,with the  water  changed daily.The specimens in the  20% carbamide peroxide group were exposed to the bleaching agent for 4 hours daily for 14 consecutive days according to the manufacture’s instructions.The specimens in the 40% hydrogen peroxide group were exposed to the bleaching agent  for 60 minutes in three 20-  minutes in one day, according to the manufacture’s instructions.  Surface roughness of all specimens was then remeasured using a profilometer.Data were analyzed using t-test,repeated measure  ANOVA,post-hoc test,and 3 -way ANOVA with Pass11  software.

In all groups,regardless of the type of bleaching agent, surface roughness after bleaching was significantly  higher than the control group (p=0.0001). In the microhybrid composite group, specimens exposed to 40% hydrogen peroxide showed greater surface roughness than those exposed to  20% carbamide peroxide (p=0.339).

Bleaching agents  can affect the surface roughness of  resin composite restorations, also,  type of bleaching agent and restorative material may affect these changes.

With the introduction of self-adhesive flowable composites to the market, the need to compare their mechanical properties, including flexural strength, with other composite materials has become increasingly important. Although self-adhesive flowable composites were developed to simplify clinical procedures, existing evidence regarding their mechanical properties, particularly flexural strength, has reported inconsistent findings. Therefore, it remains unclear whether these materials can serve as suitable alternatives to conventional flowable composites in terms of flexural strength. The aim of this study was to compare the flexural strength of a self-adhesive flowable composite (Vertise Flow) with a conventional flowable composite (Grandio Flow) during the academic year 2022–2023 at the Faculty of Dentistry, Islamic Azad University of Tehran, in an in vitro setting.

In this in vitro study, 24 composite specimens were prepared in two groups (n=12), including Vertise Flow (Kerr, USA) and Grandio Flow (VOCO, Germany). Flexural strength was measured using a three-point bending test in accordance with ISO 4049. Data were analyzed using the Shapiro–Wilk test for normality assessment. Based on Levene’s test results, mean flexural strength values were compared using the Independent Samples t-test.

The mean flexural strength was 188.62 ± 18.25 MPa for Grandio Flow and 147.62 ± 17.53 MPa for Vertise Flow. The difference between the groups was statistically significant (p < 0.001).

Within the limitations of this in vitro study, Grandio Flow demonstrated higher flexural strength compared to Vertise Flow. However, extrapolation of these findings to clinical conditions requires further investigations under intraoral conditions.

The nasal cartilaginous septum is one of the key structural elements in rhinoplasty and serves as the main source for graft harvesting. Its dimensions and morphology vary considerably among individuals, which can influence surgical planning and outcomes. Precise preoperative evaluation of the cartilage’s morphometric parameters may help optimize graft utilization and preserve nasal stability.

This descriptive cross-sectional study was conducted on 148 patients who were referred to Velayat Hospital, Guilan University of Medical Sciences, between 2021 and 2023 for midface cone-beam computed tomography (CBCT) imaging that included the nasal region. The nasal septal cartilage was reconstructed three-dimensionally using NEWTOME software. Statistical tests were performed at a significance level of 0.05.

The mean age of participants was 37.99 ± 3.79 years (58.8% female, 41.2% male). The most common deviation type was C-shaped (31.8%), while the least frequent was reverse C-shaped (19.6%). Males had significantly longer cartilage (p = 0.044), whereas females had a greater width (p = 0.029). Younger patients (≤ 38 years) exhibited significantly larger dimensions (p < 0.01). Surface area differed significantly among deviation types (p < 0.001), with the maximum area observed in S-shaped deviations.

CBCT enables accurate visualization of the nasal septal cartilage, helping predict harvestable graft volume and identify deviation patterns. Age and septal morphology significantly affect cartilage surface area and play a crucial role in individualized rhinoplasty planning.

The increasing integration of artificial intelligence (AI) into dentistry necessitates an evaluation of dentists’ awareness, knowledge, and attitudes in this field. This Study aimed to evaluate the Attitudes of Students, Residents, and Faculty Members of Tehran Islamic Azad University of Medical Sciences towards the Application of Artificial Intelligence in Dentistry during the Academic Year 2024-2025.

This descriptive cross-sectional study was conducted on a total of 243 participants, including 138 undergraduate dental students, 49 postgraduate dental residents, and 56 faculty members. To assess attitudes toward the application of artificial intelligence (AI) in dentistry, a questionnaire was developed based on a previous study. Face validity of the instrument was confirmed by experts, and its reliability was verified using Cronbach’s alpha (0.68). The questionnaire consisted of two main sections: Demographic information Attitude-related items (questions 1–15), Respondents were asked to indicate their level of agreement on a Likert scale. To examine the effect of independent variables on the total questionnaire score, a multiple linear regression model was employed.

Overall, the mean attitude score was 39.46 ± 8.54. The mean attitude scores were 41.55 ± 7.94 among faculty members, 35.85 ± 10.04 among residents, and 39.90 ± 7.85 among students. With increasing age, the average attitude score increased (p=0.004). Men had a higher average attitude score towards the use of artificial intelligence in dentistry than women (p=0.041). With increasing academic year, the average attitude score decreased (p=0.008). Position (faculty members, students, residents) did not have a significant effect on the average attitude score towards the use of artificial intelligence in dentistry (p=0.223).

The attitudes of students, residents, and faculty members were at a moderate level. Overall, dental students demonstrated a positive perspective toward the use of AI in dentistry, particularly in areas such as radiographic diagnosis, implant placement planning, and the diagnosis of periodontal diseases.

Management of immature permanent molars with necrotic pulp and apical periodontitis is clinically challenging. This study reports a case of regenerative endodontic treatment (RET).

Following clinical and radiographic diagnosis, the root canals were minimally instrumented and chemically disinfected using 1.5% sodium hypochlorite. An intracanal medicament consisting of a mixture of calcium hydroxide, ciprofloxacin, and metronidazole was placed for four weeks. In the subsequent visit, after irrigation with EDTA, apical bleeding was induced to form a blood clot containing stem cells, and mineral trioxide aggregate (MTA) was applied as a coronal barrier. After MTA setting, the tooth was restored with glass ionomer and a preformed stainless steel crown (SSC). At 3-month, 6-month, and 1-year follow-ups, the patient was asymptomatic, and radiographs demonstrated healing of periapical lesions and continued root development.

RET using a combination of calcium hydroxide and antibiotics with coronal sealing by MTA is an effective option for managing necrotic immature permanent molars. Future studies could compare RET with apexification techniques to better evaluate its impact on periapical healing.

Dental nanomaterials, with their unique properties, have the potential to revolutionize restorative and preventive dentistry. Despite the diversity of nanomaterials, there is insufficient clarity about their mechanisms, clinical benefits, and limitations. The aim of this study is to provide a comprehensive overview of the principles, innovations, and applications of nanomaterials in dentistry.

This study was conducted as a narrative review. A structured search of PubMed, Scopus, and Web of Science was performed for articles published between 2010 and 2025. Original laboratory, animal, and clinical studies on dental nanomaterials were included, while irrelevant or methodologically weak studies were excluded. The findings were analyzed qualitatively using descriptive and comparative approaches. No formal statistical analysis was performed due to the narrative nature of the review.

Dental nanomaterials include nanocomposites, metal nanoparticles, nanotubes, PLGA, and bioactive glasses, which offer clinical benefits such as increased hardness and durability of restorative materials, antibacterial properties, remineralization, and targeted drug delivery. However, limitations such as potential toxicity, challenges of stabilization in resin, and regulatory restrictions have also been reported.

Understanding the physical principles and applications of dental nanomaterials is essential to exploit the benefits and reduce the limitations. Nanotechnology has the potential to significantly improve clinical outcomes and patient care in restorative and preventive dentistry by improving existing materials and providing novel applications.