Biomechanics of Central Incisor Endocrowns with Different Lengths and Milled Materials after Static and Vertical Loading: A Finite Element Study.

Purpose: The aim of this study was to compare and assess the stress distribution and failure possibility of endodontically treated central incisor protected with endocrowns with different heights, with various CAD-CAM blocks such as IPS e.max CAD, Katana Zirconia, and Zolid Fx Zirconia. Materials and Methods: A root canal-treated central incisor (plastic model) restored with an endocrown was scanned with a laser scanner to prepare a control model with a CAD software and then transferred to an FEA software. Proposed crown heights were 2, 4, and 6 mm. The model that was duplicated and restored with CAD-CAM blocks, IPS e.max CAD, Katana Zirconia, and Zolid Fx Zirconia were tested as endocrown materials. Bone geometry was simplified to be two coaxial cylinders in all models. Stress distributions under 50 N axial and oblique (with 135° angle from the vertical plane) loading were analyzed. Each model was then subjected to two occlusal loading conditions-the lingual slope of the incisal edge and the junction between incisal and middle thirds. Eighteen runs and calculations were performed to determine the endocrown height and material effect. Results: The results showed a minor or negligible effect of changing the endocrown material. Increasing endocrown height was shown to reduce stresses and deformations on most of the model components (bone, gutta-percha, periodontal ligament, and endocrown), except root and cement. Differences in deformations and stresses between the two models of 4 and 6 mm were relatively smaller (ranged between 1% and 30%) compared to those between the 2 and 4 mm models (ranged between 10% and 400%). Conclusions: The material used to fabricate endocrowns did not show considerable effect on the underlying structures. However, the endocrown design (2, 4, and 6 mm height) was shown to affect all components of the studied systems. Increasing endocrown height is recommended for bone, periodontal ligaments, and endocrown body, as it reduces stresses and deformations. On the other hand, it dramatically increases stresses on the root and cement layer. Smaller endocrown sizes represent an acceptable treatment option when there is a healthy periodontal state, while using larger sizes will be more suitable when there is a periodontal compromise with bone loss.

PEEK surface treatment on surface roughness and bond integrity to composite resin utilizing Er: YAG, Rosebengal activated by PDT, and aluminum trioxide particles.

AIMS: To evaluate the impact of conditioning protocols, aluminum trioxide (Al2O3), Er:YAG laser (EYL), and Rosebengal (RB), on the surface roughness (Ra) and shear bond strength (SBS) of polyetheretherketone (PEEK) attached to composite restorations. METHOD: Eighty PEEK discs in total were produced and then divided into four groups (n = 20). Group1:Sulfuric acid (SA), Group 2: PDT (RB), Group 3: Al2O3, Group 4 EYL, respectively. The Ra of PEEK discs was evaluated using the surface profilometer. After being luted, the discs were attached to composite resin discs. After that, samples were put to SBS testing on a Universal testing apparatus. A stereo microscope was also used to evaluate the type of breakdown. The data were analyzed using Tukey's test and one-way analysis of variance. RESULTS: The SA treated group exhibited the highest Ra. Nevertheless, the RB specimens activated by PDT treatment had the lowest mean Ra score. The group that received the treatment of SA exhibited the highest average score of SBS. In contrast, specimens treated with PDT and activated by RB exhibited the lowest levels of bond fidelity. Cohesive failure emerges as the prevailing kind of fracture within the various groups subjected to testing. CONCLUSION: The utilization of Al2O3, RB activated by PDT, and EYL shows promise as a viable substitute for Sulfuric acid in enhancing the bond integrity of composite cement and surface roughness in PEEK materials.

Modulation of implants PEEK to composite resin shear bond strength and surface roughness on pre-treatment with contemporary air abrasion techniques vs photodynamic therapy vs conventional diamond grit bur.

AIM: The chief aim of the study was to determine/equate the surface roughness (SRa) and shear bond strength (BS) of pretreated PEEK discs with contemporary air abrasion techniques, photodynamic (PD) therapy by curcumin photosensitizer (PS) and conventional diamond grit straight fissure bur adhered to the composite resin discs. MATERIAL AND METHOD: Two hundred discs of PEEK were prepared of 6 mm × 2 mm × 10 mm dimension. The discs were randomly divided into five groups (n = 40) for treatment, Group I: treatment with deionized distilled water (control group); Group II: PD therapy using curcumin PS; Group III: discs treated and abraded with air-borne particles (ABP) silica (30 µm particle size) modified alumina (Al); Group IV: ABP of alumina (110 µm particle size); and Group V: The PEEK were finished with 600-µm grit size straight diamond cutting bur installed in high speed hand-piece. The surface profilometer was used to evaluate the values of surface roughness (SRa) of pretreated PEEK discs. The discs were luted and bonded to discs of composite resin. The bonded PEEK samples were placed in Universal testing machine to evaluate shear BS. The type of BS failure for PEEK discs pre-treated with five regimes respectively was evaluated under stereo-microscope. The data was statistically analyzed using one-way ANOVA and the comparisons between mean values of shear BS were evaluated by Tukey's test (ρ≤0.05). RESULTS: The PEEK samples pre-treated with diamond cutting straight fissure burs displayed statistically significant highest value of SRa values (3.258± 0.785 µm). Similarly, the shear BS was observed to be higher for the PEEK discs pre-treated with straight fissure bur (22.37±0.78 MPa). A comparable difference but not statistically significant difference was observed between PEEK discs pre-treated by curcumin PS and ABP-silica modified alumina (ρ ≥ 0.05). CONCLUSION: PEEK discs pre-treated with diamond grit straight fissure bur displayed highest values of SRa and shear BS. It was trailed by ABP-Al pre-treated discs; whereas the SRa and shear BS values for the discs pre-treated with ABP-silica modified Al and curcumin PS did not show competitive difference.

Use of final irrigants MTAD, Salvedora Perscia, Malachite green, and Ti-sapphire laser on push-out bond strength of Zirconia post.

AIM: Evaluation of the push-out bond strength (PBS) of zirconia post-bonded to radicular dentin after using different final irrigants (MTAD, Malachite green (MG), Ti-sapphire laser and Salvadora persica (S.persica). MATERIAL AND METHOD: Forty human permanent single-rooted were decoronated above the cement-enamel junction. An experienced endodontist performed all the root canal instrumentation using ProTaper universal rotary files. Canals were irrigated using 5.25% NaOCl solution followed by EDTA as a final sterilant. Obturation with gutta-percha using AH Plus sealer was performed. Post-space preparation was completed using Gates Glidden and specimens were randomly assigned to four groups based on the final disinfectant received (n=10). Group 1: 5.25% NaOCl + MTAD, group 2: 5.25% NaOCl + MG, group 3: 5.25% NaOCl +Ti-sapphire laser, and group 4: 5.25% NaOCl + S. persica. The chemically polymerized resin was used to lute zirconia posts. PBS and failure mode analysis were performed using a universal testing machine and stereomicroscope at 40X magnification. Data were compared between the two groups with 95% CI using one-way analysis of variance (ANOVA) with the Tukey post hoc test. p=0.05. RESULTS: Group4(5.25% NaOCl+ S.persica) specimens demonstrated the maximum (8.94±0.14 MPa) bond strength. Conversely, the apical third of Group 2 (5.25% NaOCl+ MG) (2.87±0.15 MPa) samples revealed the minimum bond strength scores. Intergroup comparison exposed that Group 1 (1.3% NaOCl+ MTAD), Group 3 (5.25% NaOCl+Ti-sapphire laser), and Group 4 (5.25% NaOCl+ S. persica) at all three-thirds unveiled no significant difference in PBS (p<0.05). CONCLUSION: Ti-sapphire laser and Salvedora Persica possess the potential to be used as a final root canal irrigant to improve the push-out bond strength of zirconia post-to-root dentin.

Retentive Forces and Deformation of Fitting Surface in RPD Clasp Made of Polyether-Ether-Ketone (PEEK).

BACKGROUND: Polyetheretherketone (PEEK) has provided the option to fabricate RPDs with aesthetics unlike metal RPDs, but little attention has been paid to its suitability, especially towards the retentive forces and deformation of the clasp. This study aimed to examine the retentive forces and the fitting surface (inner surface) deformation of clasps made from PEEK and compare it with cobalt-chromium (Co-Cr) clasp. METHODS: Forty-two circumferential clasps (14 Co-Cr and 28 PEEK) were fabricated and divided into two groups with clasp undercuts (0.25 mm and 0.5 mm) with thicknesses of 1 mm and 1.5 mm. Each was examined for retentive forces after cycle test on its abutment for 360 cycles. Initial and final retentive forces were recorded. The fitting surface deformation was determined using 3-Matic research analysis software. RESULTS: The results revealed that highest mean initial retentive force was of Co-Cr clasps with 0.50 mm undercut 22.26 N (±10.15 N), and the lowest was the 1 mm PEEK clasps with 0.25 mm undercut 3.35 N (±0.72 N) and highest mean final retentive force was the Co-Cr clasps with 0.50 mm undercut 21.40 N (±9.66 N), and the lowest was the 1 mm PEEK clasps with 0.25 mm undercut 2.71 N (±0.47 N). PEEK clasps had a lower retentive force than Co-Cr clasps with 0.50 undercut. PEEK clasps (1.5 mm) at 0.25 mm undercut had the least deformation (35.3 µm). PEEK showed significantly less deformation (p ≤ 0.014) than Co-Cr. CONCLUSION: The deformation of PEEK clasps fitting surface was lower than Co-Cr clasps and retentive forces were close to the Co-Cr clasps, suggesting the use of PEEK as an aesthetic clasp option for RPD framework.

Dimensional Stability of Light-Activated Urethane Dimethacrylate Denture Base Resins.

An accurate and dimensionally stable trial denture base is required for a successful denture. The aim of this in vitro study was to assess the dimensional stability of a light-activated urethane dimethacrylate (UDMA) visible light cure (VLC) denture base with three fabrication techniques and different curing cycles. Forty-five VLC denture base samples were divided evenly into three groups. Group A used a conventional fabrication technique with a curing cycle of 5 min. Group B used a modified fabrication technique with two 4-min curing cycles. Group C used a multi-step fabrication technique with three curing cycles (4 min, plus 4 min, plus 2 min). The samples were sectioned and observed under a stereomicroscope to measure the discrepancy between the sample and the master cast. The mean dimensional discrepancy (mm) at the molar region at mid-palate, after 24 h in Group A, B and C was 0.790 mm, 0.741 mm and 0.379 mm, respectively; at the right ridge crest, it was 0.567, 0.408 and 0.185, while at the left ridge crest it was 0.475, 0.331 and 0.125, respectively. Statistical analysis showed significantly different dimensional discrepancies among the groups at all three sites; right ridge crest (F = 93.54, p < 0.001), left ridge crest (F = 105.96, p < 0.001) and mid-palate (F = 125.53, p < 0.001). Within the limitations of this laboratory study, it can be concluded that the denture base using a multi-step fabrication technique with three curing cycles provides better adaptation than the conventional technique. The significance of the study is that clinicians should consider performing denture base fabrication using a multi-step technique to enhance adaptation and hence the stability of the dentures for patients.

Therapeutic efficacy of adjunctive photodynamic therapy in the treatment of denture stomatitis.

BACKGROUND: The present report assessed the efficacy of curcumin-mediated photodynamic therapy (CUR-mediated PDT) as an adjunct to antifungal gel treatment by evaluating the salivary interleukin-6 (IL-6) and matrix metalloproteinases-8 (MMP-8) levels together with Candida species counts in denture stomatitis (DS) patients. METHODS: In total, 50 DS subjects were randomly categorized into 2 groups: Group-1: subjects who received the antifungal gel treatment and Group-2: participants who received CUR-mediated PDT. The Sabourad Dextrose Agar and CHROMAgar were utilized for evaluating Candida species counts, while the Enzyme-Linked Immunosorbent Assay was employed to estimate the salivary levels of IL-6 and MMP-8. All clinical evaluations were performed at the baseline, 1 month, and 2 months. RESULTS: In total, group-2 subjects showed a significant decrease in Candida albicans (C. albicans) counts on both follow-ups (i.e., 1-month and 2-month) than group-1 participants. C. krusei count also reduced in group-2 subejcts than group-1 participants at the 2nd follow-up as compared to the baseline, nevertheless, a slight increase in C. krusei count was noticed in group-2 subjects at the 2nd follow-up than the 1st follow-up. The salivary IL-6 and MMP-8 levels in both groups reduced significantly at both follow-ups than the baseline. According to the stepwise logistic regression analysis, no statistically significant correlation was observed between Candida species count and other parameters such as age and gender of the patient, duration of DS, and frequency of treatment(s). CONCLUSION: CUR-mediated PDT is an efficaciousness therapeutic modality for alleviating Candida species counts on the surface of denture and the palatal mucosa, as well as improving the salivary IL-6 and MMP-8 levels in DS patients.

Multifocal Intraoral Melanoacanthomas: Two Case Reports and a Literature Review.

Intraoral melanoacanthoma is a rare, reactive pigmented lesion that is mostly seen in black individuals with a tendency to occur more frequently in younger females. The color of melanoacanthoma may vary from brown to black, and it is commonly seen as a solitary lesion in the buccal mucosa. This lesion requires no treatment, and no malignant potential has been observed to date. The clinical presentation of multifocal oral melanoacanthoma (MOMA) (the rate of growth and the recurrence) is usually diagnostic. On the other hand, solitary oral melanoacanthoma might be difficult to diagnose, and a biopsy should be performed and examined by a well-trained oral pathologist. Here, we report two cases of MOMA with an unusual location in one case.

Recurrent Dentinogenic Ghost Cell Tumor: A Case Report.

BACKGROUND Dentinogenic ghost cell tumor (DGCT) is a rare, locally invasive odontogenic neoplasm, considered as a solid variant of the calcifying odontogenic cyst (COC). DGCT accounts for only 2% to 14% of all COCs and less than 0.5% of all odontogenic tumors. It is characterized by an ameloblastomatous odontogenic epithelium and the presence of ghost cells and dentinoid material. CASE REPORT A 42-year-old male patient presented to the clinic with recurrent pain and swelling in the left maxilla. The patient had a similar presentation 3 years before, which had been managed by excisional biopsy and was misdiagnosed as unicystic ameloblastoma. Examination revealed a mild swelling in the left cheek with boney expansion on the posterior area of the left maxilla, with mobility in adjacent teeth. Radiographic evaluation revealed a large, well-demarcated radiolucent lesion with a sclerotic border involving the left maxilla and associated with root resorption in the adjacent teeth. An incisional biopsy was performed, and a diagnosis of DGCT was made. Segmental maxillectomy with safe margins was conducted, considering the aggressiveness of this pathological entity. The defect was reconstructed using the buccal fat pad. Histopathology examination confirmed the diagnosis of DGCT, which was characterized by ameloblastomatous odontogenic epithelium, dentinoid material, and ghost cells. One month follow-up revealed good healing of the surgical site. The patient was scheduled for regular follow-up. CONCLUSIONS This case reports the aggressiveness and high recurrence rates of DGCT. It is recommended to treat DGCT aggressively with safe margins and a long-term follow-up.

Factors affecting SARS-CoV-2 (COVID-19) pandemic, including zoonotic, human transmission and chain of infection. Reducing public health risk by serum antibody testing, avoiding screening in unhygienic places and false PCR reporting. A scientific review

During December 2019, a rapid increase in the number of SARS-CoV-2 (COVID-19) cases was reported worldwide. We investigated several factors for rapid increase in SARS-COV-2. Genomic sequence reveals that domestic and wild animals were likely ancestors and zoonotic source for SARS-CoVs, MERS-CoVs, and SARS-CoV-2; these viruses replicated in animals and humans during past several decades, exhibiting diverse mutations and self-limiting diseases except during outbreaks. SARS-CoV-2 has been retrospectively isolated in different studies in August 2019, several months before Wuhan reported. Hence, there is a possibility that viruses went undetected and infecting sub-clinically, in past several years, and SARS-CoV-2 antigens and neutralizing antibodies may have been present in humans since years. All SARS-CoVs are basically respiratory viruses, spread by droplets, hence droplet precautions are essential. Furthermore, silent phase of transmission (asymptomatic/subclinical) can be beneficial for humans. Lack of symptoms eventually lessen virus transmission and reduce the pathogen's long-term survival and provide strong humoral herd immunity (with sropositivity and diverse antibodies) up to several years and during epidemics. RT-PCR has low sensitivity and specificity, carries a high risk of handling live virus antigens, and requires difficult protocols. As viral load also sharply declines after few days of onset of infection, this technique might overlook infection. Furthermore, SARS-CoV-2 infection may be present in blood when oropharyngeal swabs are negative by RT-PCR. Conversely, antibodies against SARS-CoVs develop robustly in by reduced amount of antigens and ELISA for diagnosing antibodies demonstrates 100% specificity and 100% sensitivity, even in clinically asymptomatic individuals. These antibodies can be used for serologic surveys, monitoring and screening (AU)

Pediatric Stainless-Steel Crown Cementation Finite Element Study.

OBJECTIVE: To study the effect of using different cement types under pediatric stainless-steel crown (SSC) around mandibular second primary molar using three-dimensional (3D) finite element analysis. MATERIALS AND METHODS: A 3D finite element model was built for pediatric mandibular molar by laser scanning of natural extracted tooth. Four types of cement (zinc phosphate, glass ionomer, resin-modified glass ionomer, and resin) of 200 µm layers thickness were tested under a stainless-steel crown of 130-µm thickness. Twelve case studies were reported within this research, as the applied load of 330 N was tested with three angulations: vertical, oblique at 45°, and laterally. RESULTS: Linear static stress analysis was performed. The resultant stresses and deformations' distribution patterns did not change with cement type, while the values were altered. All deformations and stresses were found within the normal range. CONCLUSIONS: Analysis results indicated that using stiffer cement material increases tooth structure stresses and reduces crown body stresses and deformations, while bone was nearly insensitive to cement type.

Knowledge and attitude regarding child abuse among primary health care physician in Abha, Saudi Arabia, 2018.

BACKGROUNDS: Child abuse or child maltreatment is physical, sexual, or psychological maltreatment or neglect of a child or children, especially by a parent or other caregiver. Child abuse may include any act or failure to act by a parent or other caregiver that results in actual or potential harm to a child, and can occur in a child's home or in the organizations, schools, or communities the child interacts with. This study was conducted to assess the primary health care (PHC) centers' physicians' knowledge and attitude toward child abuse including its types, and child neglect with their behavior regarding reporting of abuse cases. METHODS: A cross-sectional study was conducted in Abha which is the capital of Aseer Province, including all PHC physicians (about 475) working in PHC centers. Data regarding physicians' demographic characteristics, perception, and awareness regarding child abuse and neglect were collected by self-administrative questionnaire in the PHC center during their time between patients' consultation. RESULTS: The study included 300 PHC physicians whose ages ranged from 25 to 50 years old with mean age of 28 years. About 65% of the physicians were males and 69% of them were married with about 73% having at least one child. Overall, 96.3% of the physicians recorded good awareness level regarding types of child abuse and 97.3% recorded good awareness level regarding child neglect patterns. Underreporting of child abuse cases was recorded by about 64% of physicians. CONCLUSION: Regarding child abuse and neglect, PHC physicians have good knowledge, optimal attitude, and positive perception. There was also the problem of underreporting of suspected child abuse cases among PHC physicians in Saudi Arabia, with many barriers to report, such as community traditions; unclear reporting strategy was identified.

Knowledge, attitude and practice of pediatricians and pharmacists in Riyadh City toward the use of sugar free medications.

OBJECTIVE: This study was intended to assess the knowledge, attitude and practice of pediatricians and pharmacists about sugar free medications (SFMs) and their impact on oral health. MATERIALS AND METHODS: Self-administered close ended questionnaire was handed out to all pediatricians and pharmacists in five tertiary hospitals in Riyadh (King Khalid University Hospital, King Saud Medical City, King Fahad Medical City, Prince Sultan Medical Military City, Security Forces Hospital) to investigate the knowledge, attitude and practice concerning SFMs. RESULTS: Eighty-five pediatricians and 77 pharmacists participated in this study. The results showed that pediatricians and pharmacists have a good knowledge, but negative attitude toward SFMs. Only (5.9%) of pediatricians had formal undergraduate training which is significantly lower than pharmacists (15.6%) (p = 0.04). One-third of pediatricans and pharmacists prescribe or dispense SFMs. The most influencing factors toward prescription (pediatrician) of SFMs was the medical status of the patient (70.6%), while the most influencing factor of dispensing (pharmacists) SFMs was the availability in the pharmacy (64.9%). Two-third of pediatricians (67%) guide the parents about the risk associated with sugar-containing medications (SCMs) which is significantly higher than pharmacists (p < 0.0001). Also, 53% of pediatricians recommend oral hygiene instructions when prescribing SCMs which is also significantly higher than pharmacists (p = 0.0 02). CONCLUSION: There is a considerable knowledge about SFMs and its impact on dental caries, among pediatricians and pharmacists participated in this study. However, their attitude toward prescribing or dispensing SFMs was not positive and may be linked to the gap in knowledge. Further training and education of healthcare providers regarding the use of SFMs and its negative impact on dental caries has to be reiterated.