Journal of Dental Research, Dental Clinics, Dental Prospects
Volume:18 Issue: 4, Autumn 2024

 The accurate timing of growth modification treatments is crucial for optimal results in orthodontics. However, traditional methods for assessing growth status, such as hand-wrist radiographs and subjective interpretation of lateral cephalograms, have limitations. This study aimed to develop a semi-automated approach using machine learning based on cervical vertebral dimensions (CVD) for determining skeletal maturation status.

 A dataset comprising 980 lateral cephalograms was collected from the Department of Orthodontics, Shahid Beheshti Dental School in Tehran, Iran. Eight landmarks representing the corners of the third and fourth cervical vertebrae were selected. A ratio-based approach was employed to compute the values of C3 and C4, accompanied by the implementation of an auto_error_reduction (AER) function to enhance the accuracy of landmark selection. Linear distances and ratios were measured using the dedicated software. A novel data augmentation technique was applied to expand the dataset. Subsequently, a stacking model was developed, trained on the augmented dataset, and evaluated using a separate test set of 196 cephalograms.

The proposed model achieved an accuracy of 99.49% and demonstrated a loss of 0.003 on the test set.

  By employing feature engineering, simplified landmark selection, AER function, data augmentation, and eliminating gender and age features, a model was developed for accurate assessment of skeletal maturation for clinical applications.

 The wear resistance of lithium disilicate glass ceramics remains inadequately understood. Therefore, the primary objective of this in vitro study was to digitally assess the wear characteristics of lithium disilicate and zirconia-reinforced lithium disilicate pressable ceramics following chewing simulation.

 Twenty-two onlay ceramic restorations were fabricated on epoxy dies replicated from the maxillary first premolar ivory tooth master die. The onlay samples were randomly allocated to two equal groups (n=11) based on the material used: group L (lithium disilicate [IPS e.max Press]) and group Z (zirconia-reinforced lithium disilicate [Vita Ambria]). Self-adhesive resin cement was used to cement all of the samples. Each sample was occluded with the buccal cusps of healthy human upper first premolar teeth (n=22). Subsequently, all the samples were scanned using an intraoral scanner (Medit i500) at baseline and after chewing simulation. The acquired standard tessellation language (STL) files of baseline and post-chewing simulation data were superimposed, and the volumetric loss (mm3) and wear depth (μm) of the materials and their enamel antagonists were calculated. Statistical analysis was performed using independent t-test (P=0.05).

 There was no statistically significant difference in the wear behavior of Vita Ambria compared to IPS e.max (P<0.05). Similarly, there was no statistically significant difference in the wear behavior of their enamel antagonists (P<0.05).

 IPS e.max Press and Vita Ambria ceramics demonstrated comparable wear behavior.

 In implant-supported overdentures increase in the number of implants improves the retention and stability of the overdentures. A direct correlation exists between prosthesis retention and patient satisfaction. Therefore, this experimental study assessed the effect of attachment type and implant position on the retention of mandibular implant-supported overdentures.

 A transparent acrylic resin model of the mandible was fabricated, and dental implants were positioned at the first molar area (position 6), between the lateral incisor and canine teeth (positions B and D), and first premolars (positions A and E) bilaterally. Novaloc attachments (strong, medium, and light retentive caps) were used with ABDE, 6AE6, and 6BD6 implant positions. A Dolder bar attachment was also used with the ABDE implant position. Overdenture retention was measured under vertical loading, and the maximum dislodging force (MDF) was recorded. Data were analyzed by two-way and one-way ANOVA and post hoc Tukey tests (α=0.05).

The effects of attachment type and implant position [except for ABDE and 6AE6 with light retention insert (P=0.49), and 6AE6 and 6BD6 with strong retention insert (P=0.48)], and their interaction effect were significant on MDF (P<0.01). The highest retention was recorded for bar attachment (65.15 N), with the lowest for Novaloc attachment with light retention insert at ABDE implant position (11.97 N).

  With Novaloc attachments, minimum retention was recorded in ABDE, and maximum retention was recorded in the 6BD6 implant position due to the increased distance between attachments. The strong insert showed the highest retention value, which confirmed the manufacturer’s claim. Maximum retention was recorded with the bar and clip attachment.

Candida albicans in the oral cavity causes denture-induced stomatitis, but current treatments have side effects and contribute to drug resistance. Selenium nanoparticles (SeNPs) show promise as an antimicrobial agent, but their effectiveness against C. albicans is unknown and warrants further research.

 Acrylic resins containing different concentrations of SeNPs (0.2, 2, and 10 g/mL) were formulated and evaluated against C. albicans isolates. The minimum inhibitory concentration (MIC) of SeNPs was determined, and a fungal biofilm was developed on acrylic samples. The quantity of biofilm was assessed using scanning electron microscopy (SEM) and optical density (OD) at 570 nm after staining with crystal violet. Statistical analysis was performed using STATA software, with Kruskal-Wallis and Mann-Whitney tests to establish significance (P<0.05).

 The MIC of SeNPs was 25%. The OD in the group with 10% SeNPs was 0.477 and 0.547 in the group with 0.2%. Kruskal-Wallis test results showed that at least two groups among those studied had significant differences (P=0.0273). In pairwise comparisons, the differences between all the groups were statistically significant (P=0.049). SEM analysis confirmed the destruction of C. albicans cell walls, leading to reduced colonization, with the 10% group showing the highest efficacy.

The study demonstrated that SeNPs are effective against C. albicans colonization when combined with acrylic resin. Specifically, SeNPs exhibited enhanced antifungal properties at a concentration of 10%. These findings confirm that SeNPs are a promising alternative to traditional antifungal agents for treating oral candidiasis and denture-induced stomatitis.

 Zirconia-reinforced lithium disilicate (ZLD) is a promising material for esthetic dental restorations due to its strength, translucency, and color stability. However, its durability under accelerated aging conditions needs further investigation. The present in vitro study evaluated the effect of UV accelerated aging on the translucency and color stability of ZLD at varying thicknesses, using IPS e.max Press (LD) as a reference.

 Seventy-two samples were divided into two groups: high translucent (HT) Vita Ambria (ZLD) and IPS e.max Press (LD) (n=36, each). Each group was further subdivided into four thicknesses: 0.5, 1.0, 1.5, and 2.0 mm (n=9). The samples were fabricated, polished, and subjected to UV weathering for 384 hours, simulating one year of clinical service. Translucency and color changes were assessed using a spectrophotometer. Data were analyzed using SPSS 20, with independent t-test, paired t-test, and one-way ANOVA at a significance level of P≤0.05.

Vita Ambria exhibited significantly higher translucency before and after aging compared to IPS e.max press at all thicknesses (P=0.000). In both materials, translucency decreased when the thickness increased (P=0.000), observed before and after UV aging. Vita Ambria also displayed a greater color change (ΔE=2000) compared to IPS e.max press across all thicknesses (P=0.000).

  ZLD exhibited higher translucency than LD before and after accelerated artificial aging, indicating that the accelerated aging process adversely impacted the optical properties of the tested material. However, LD demonstrated superior color stability.

Considering the few studies on the effect of bleaching protocols on the color properties of a newly developed monochromatic universal composite resin, the present study evaluated the effect of different bleaching protocols on the color change and translucency of Omnichroma (OMN) composite resin.

  In this laboratory study, 45 cylindrical OMN composite resin disks with a diameter of 10 mm and a thickness of 2 mm were used. The samples were randomly divided into three groups (n=15) based on the bleaching protocols: group 1: 40% hydrogen peroxide (HP) for 20 minutes, twice a day for three sessions one week apart; group 2: 20% carbamide peroxide (CP) for 8 hours a day, for 14 consecutive days; group 3: 40% HP with Nd:YAG laser (HP+Nd:YAG laser) applied on the gel for 30 seconds twice. Baseline and post-bleaching measurements of color parameters were done using a Vita Easyshade spectrophotometer. Data was analyzed using paired-samples t-test, one-way ANOVA, and post hoc Tukey tests (P<0.05).

  All the bleaching protocols significantly changed the color (P<0.001) and translucency (P<0.001) parameters. CP caused the most color changes (P<0.05) and translucency (P<0.05), which were significant, and color and translucency changes caused by HP and HP+Nd:YAG laser were not significant (P>0.05).

  Bleaching caused a noticeable change in the color and translucency of the OMN composite resin. The effect of the at-home bleaching protocol was greater than the in-office ones.

 Chewable vitamins are dietary supplements in which vitamins are combined with a flavor that appeals to children. The acidic nature of some vitamins and some flavoring agents may cause dental erosion. We investigated the effect of children’s chewable vitamin supplements on the loss of minerals in teeth.

 Forty-two human tooth enamel samples were prepared and randomly assigned to seven groups (n=6). Six groups contained different chewable vitamin tablets dissolved in deionized water, and a control group contained only deionized water. Each tablet was ground before its dissolution, and its pH was measured. Each tooth sample was immersed in a vitamin solution and artificial saliva in periodic cycles for 14 days. Each sample was weighed before and after immersion to calculate its weight loss percentage. Scanning electron microscopy was used to investigate the morphology of the enamel surfaces. For statistical analysis, the weight loss percentages between groups were compared using Welch’s ANOVA, followed by post hoc Dunnett’s T3 analysis (P<0.05).

 All the tested supplements were acidic, with a pH range of 2.99‒4.77. Most of the vitamin groups tested led to significant weight loss; it was greater for the vitamin C groups than the multivitamin groups. Scanning electron microscopy revealed erosion and destruction of enamel surfaces following vitamin exposure.

 All the chewable vitamin supplements were acidic, with the majority potentially eroding enamel. The erosive potential was less pronounced in vitamin supplements containing minerals.

 Platelet-rich fibrin (PRF) enhances tissue healing by releasing essential growth factors. Surgical extraction of deeply impacted mandibular third molars poses a common challenge, often leading to significant defects at the distal root of the second molar. This study explored the role of PRF in soft and hard tissue healing after surgical extraction.

This triple-blind, split-mouth, randomized controlled trial involved patients with bilateral impacted mandibular third molars. Single-stage surgical extraction was performed, and PRF was applied at one site while the other served as the control. Plaque index (PI), sulcus bleeding index (SBI), clinical attachment levels (CALs), postoperative pain, edema, tenderness, sensitivity, and bone level were assessed on day 1, day 3, first week, and first, third, and sixth months.

  Sixty-four (34 males and 30 females) patients were found eligible for assessment. The test group exhibited a significant decrease in mean pain scores compared to controls (P<0.001), notably resolving by one month. Edema scores were significantly lower in the test group at all intervals up to one month (P=0.045). Tenderness showed a significant difference at one week (P=0.001), resolving by three months. No significant hard tissue changes were noted (P=0.825).

  Significant benefits over postoperative pain, bleeding, tenderness, and initial sensitivity underscored the importance of PRF in soft tissue healing following impacted mandibular third molar extraction. However, no improvement in bone height outlined its limited potential in hard tissue regeneration over exposed root surfaces of the mandibular second molar.

Managing benign oral soft tissue lesions presents a clinical challenge, often requiring invasive procedures with associated drawbacks. The Er,Cr:YSGG laser has emerged as a potential solution, given its precision and minimal tissue disruption in other medical contexts.

  This pre-post study involved 16 participants diagnosed with benign oral soft tissue lesions. The lesions were excised using the Er,Cr:YSGG laser (2780 nm) with 2.75‒3.75-W power outputs. Pain was quantified using a numerical rating scale from 0 to 10, and edema presence was noted. Function interference and satisfaction were graded. Healing was assessed via the Early Wound Healing Score (EHS). The observation spanned three postoperative intervals: day 1, day 3, and day 7.

This study included 16 participants with benign oral soft tissue lesions, predominantly pyogenic granuloma and fibroepithelial polyp. Initial discomfort and bleeding were common, while a small proportion reported pain. Er,Cr:YSGG laser treatment significantly reduced discomfort (VAS score) and promoted healing (EHS score) over time. Function interference decreased, and patient satisfaction improved from day 1 to day 7. Additionally, bleeding scores decreased drastically, confirming the laser’s effective hemostatic properties.

  The findings suggest that Er,Cr:YSGG laser treatment presents a promising, less invasive approach for managing oral benign soft tissue lesions, prioritizing patient well-being and contentment alongside successful lesion removal.

Understanding the characteristics of the pterygoid hamulus (PH) is crucial for diagnosing and treating various oropharyngeal and craniofacial conditions. It also aids in interpreting radiographs and diagnosing unexplained oropharyngeal pains. Cone-beam computed tomography (CBCT) is a valuable tool, offering clinical insights into this previously understudied area. Accordingly, this study aimed to evaluate the morphology and dimensions of the PH and its changes by ageing in 20-40-year-old women in the Dental Branch of Islamic Azad University of Sciences, Tehran, Iran.

  This cross-sectional study was conducted on CBCT scans from 258 women aged 20-40. The morphology, length, width, and angle of the PH in coronal and sagittal planes were investigated.

The average length of the right and left hamulus was 5.50±1.37 and 5.37±1.36 mm. The average width of the right and left hamulus was 2.16±0.72 and 2.11±1.06 mm. The average coronal angle of the right and left hamulus was 22.3±9.79° and 30.16±8.99°. The average sagittal angle of the right and left hamulus was 26.11±7.26° and 26.34±7.63°. In contrast with the sagittal angle, the right and left hamulus’s length, width, and coronal angles were not symmetrical. Slender morphology was the most frequent morphology, and it was symmetrical only in the 20-30-year-old age group. Finally, no variable was affected by ageing.

  Hamulus dimensions and morphology did not change with ageing in women aged 20-40. The PH symmetry varied by age group. Also, CBCT was a suitable tool for investigating hamulus changes.