Quantum mechanical analysis of yttrium-stabilized zirconia and alumina: implications for mechanical performance of esthetic crowns.

BACKGROUND: Yttrium-stabilized zirconia (YSZ) and alumina are the most commonly used dental esthetic crown materials. This study aimed to provide detailed information on the comparison between yttrium-stabilized zirconia (YSZ) and alumina, the two materials most often used for esthetic crowns in dentistry. METHODOLOGY: The ground-state energy of the materials was calculated using the Cambridge Serial Total Energy Package (CASTEP) code, which employs a first-principles method based on density functional theory (DFT). The electronic exchange-correlation energy was evaluated using the generalized gradient approximation (GGA) within the Perdew (Burke) Ernzerhof scheme. RESULTS: Optimization of the geometries and investigation of the optical properties, dynamic stability, band structures, refractive indices, and mechanical properties of these materials contribute to a holistic understanding of these materials. Geometric optimization of YSZ provides important insights into its dynamic stability based on observations of its crystal structure and polyhedral geometry, which show stable configurations. Alumina exhibits a distinctive charge, kinetic, and potential (CKP) geometry, which contributes to its interesting structural framework and molecular-level stability. The optical properties of alumina were evaluated using pseudo-atomic computations, demonstrating its responsiveness to external stimuli. The refractive indices, reflectance, and dielectric functions indicate that the transmission of light by alumina depends on numerous factors that are essential for the optical performance of alumina as a material for esthetic crowns. The band structures of both the materials were explored, and the band gap of alumina was determined to be 5.853 eV. In addition, the band structure describes electronic transitions that influence the conductivity and optical properties of a material. The stability of alumina can be deduced from its bandgap, an essential property that determines its use as a dental material. Refractive indices are vital optical properties of esthetic crown materials. Therefore, the ability to understand their refractive-index graphs explains their transparency and color distortion through how the material responds to light..The regulated absorption characteristics exhibited by YSZ render it a highly attractive option for the development of esthetic crowns, as it guarantees minimal color distortion. CONCLUSION: The acceptability of materials for esthetic crowns is strongly determined by mechanical properties such as elastic stiffness constants, Young's modulus, and shear modulus. YSZ is a highly durable material for dental applications, owing to its superior mechanical strength.

The effectiveness of botulinum toxin for temporomandibular disorders: A systematic review and meta-analysis.

OBJECTIVE: The current body of research on utilizing botulinum toxin (BTX) to manage temporomandibular disorders (TMDs) has not yet yielded definitive conclusions. The primary objective of this study was to determine the effectiveness of BTX in pain reduction for TMDs compared to placebo and other treatments. The secondary outcomes evaluated were adverse events, maximum mouth opening, bruxism events, and maximum occlusal force. MATERIALS AND METHODS: A literature search was performed on PubMed, Dimension Publication, Scopus, and Google Scholar. The RoB 2 tool was used for quality assessment. The mean differences in pain scores were estimated to measure the effect of BTX on pain reduction. For adverse events, the risk ratio for the incidence of side effects was calculated. RESULTS: Two hundred and sixty non-duplicate articles were identified; however, only 14 RCTS were included in this review. The total study population included 395 patients. The overall risk of bias showed a low to moderate quality of evidence. Results from 6 studies were reported only narratively; four studies were used for meta-analysis on pain reduction, and five were used for meta-analysis on adverse events. The control used in the meta-analysis was placebo injections. Results of the meta-analysis for pain reduction were statistically insignificant for the BTX group with mean differences at MD = -1.71 (95% CI, -2.87 to -0.5) at one month, -1.53 (95% CI, -2.80 to -0.27) at three months, and -1.33 (95% CI, -2.74 to 0.77) at six months. This showed that BTX treatment was not significantly better than placebo for a reduction in pain scores at 1, 3, and 6 months. Regarding safety, the placebo group showed a relative risk of 1.34 (95%CI, 0.48-6.78) and 1.17 (95%CI, 0.54-3.88) at 1 and 3 months respectively. However, the risks were not statistically significant. There was also no difference in the effectiveness of BTX compared to placebo and other treatments for maximum mouth opening, bruxism events, and maximum occlusal force. CONCLUSION: BTX was not associated with better outcomes in terms of pain reduction, adverse events, maximum mouth opening, bruxism events, and maximum occlusal force. More high-quality RCTs are needed to better understand this topic.

The flexural strength of 3D-printed provisional restorations fabricated with different resins: a systematic review and meta-analysis.

BACKGROUND: Three-dimensional (3D) printing technology has revolutionized dentistry, particularly in fabricating provisional restorations. This systematic review and meta-analysis aimed to thoroughly evaluate the flexural strength of provisional restorations produced using 3D printing while considering the impact of different resin materials. METHODS: A systematic search was conducted across major databases (ScienceDirect, PubMed, Web of Sciences, Google Scholar, and Scopus) to identify relevant studies published to date. The inclusion criteria included studies evaluating the flexural strength of 3D-printed provisional restorations using different resins. Data extraction and quality assessment were performed using the CONSORT scale, and a meta-analysis was conducted using RevMan 5.4 to pool results. RESULTS: Of the 1914 initially identified research articles, only 13, published between January 2016 and November 2023, were included after screening. Notably, Digital Light Processing (DLP) has emerged as the predominant 3D printing technique, while stereolithography (SLA), Fused Deposition Modeling (FDM), and mono-liquid crystal displays (LCD) have also been recognized. Various printed resins have been utilized in different techniques, including acrylic, composite resins, and methacrylate oligomer-based materials. Regarding flexural strength, polymerization played a pivotal role for resins used in 3D or conventional/milled resins, revealing significant variations in the study. For instance, SLA-3D and DLP Acrylate photopolymers displayed distinct strengths, along with DLP bisacrylic, milled PMMA, and conventional PMMA. The subsequent meta-analysis indicated a significant difference in flexure strength, with a pooled Mean Difference (MD) of - 1.25 (95% CI - 16.98 - 14.47; P < 0.00001) and a high I2 value of 99%, highlighting substantial heterogeneity among the studies. CONCLUSIONS: This study provides a comprehensive overview of the flexural strength of 3D-printed provisional restorations fabricated using different resins. However, further research is recommended to explore additional factors influencing flexural strength and refine the recommendations for enhancing the performance of 3D-printed provisional restorations in clinical applications.

Role of Chitosan Hydrogels in Clinical Dentistry.

Biopolymers are organic polymers that can be treated into intricate designs with porous characteristics that mimic essential biologic components. Due to their superior biosafety, biodegradability, biocompatibility, etc., they have been utilized immensely in biomedical engineering, regeneration, and drug delivery. To obtain the greatest number of results, a literature search was undertaken in scientific search engines utilizing keywords. Chitosan is used in a variety of medical sectors, with the goal of emphasizing its applications and benefits in the clinical dental industry. Chitosan can be dissolved in liquid form and combined with other substances to create a variety of products, including fibers, hydrogels, membranes, microspheres, resins, sponges, pastes, tablets, and micro granules. Chitosan has been studied in a variety of dental applications. Chitosan is used in the prevention of caries and wear, in pulpotomy to accelerate osteogenesis in guided tissue regeneration due to its hemostatic property, and primarily to benefit from its antimicrobial activity by adding it to materials, such as glass ionomer cement, calcium hydroxide, and adhesive systems. With its antibacterial activity and biocompatibility, chitosan is leading the pack as a promising ingredient in the production of dental materials. The current review provides an update on the background, fundamentals, and wide range of uses of chitosan and its gels in dental science.

Effects of Bacterial Metabolites on the Wnt4 Protein in Dental-Pulp-Stem-Cells-Based Endodontic Pulpitis Treatment.

Porphyromonas gingivalis is associated with endodontic pulpitis, causing damage to the dental pulp, leading to severe pain and a decline in quality of life. Regenerative pulp treatments using dental pulp stem cells (DPSCs) can be hindered by interactions between DPSCs and the infecting bacteria. The protein WNT family member 4 (Wnt4) plays a critical role in the differentiation of DPSCs and the regeneration of odontogenic tissue. However, the specific influence of P. gingivalis on Wnt4 remains unclear. In this study, we employed a computational approach to investigate the underlying mechanisms through which P. gingivalis-produced metabolites inhibit the Wnt4 protein, thereby diminishing the regenerative potential and therapeutic efficacy of odontogenic tissue. Among the metabolites examined, C29H46N7O18P3S-4 exhibited the strongest inhibitory effect on the Wnt4 protein, as evidenced by the lowest binding energy score of -6782 kcal/mol. Molecular dynamic simulation trajectories revealed that the binding of C29H46N7O18P3S-4 significantly altered the structural dynamics and stability of the Wnt4 protein. These alterations in protein trajectories may have implications for the molecular function of Wnt4 and its associated pathways. Overall, our findings shed light on the inhibitory impact of P. gingivalis-produced metabolites on the Wnt4 protein. Further in vitro, in vivo, and clinical studies are necessary to validate and expand upon our findings.

Static and dynamic validation of kinect for ergonomic postural analysis using electro-goniometers as a gold standard:A preliminary study.

BACKGROUND: Evaluation of the working postures and development of new techniques are paramount in reducing the awkward postures and occurrence of musculoskeletal disorders (MSDs). The Kinect sensor, a portable and cost-effective device, appears to be a promising alternative to study work postures. OBJECTIVE: The current study aimed to evaluate the validity of Kinect against the gold-standard instrument (electro-goniometers) for body joint angle measurements. METHODS: A unique software application was developed to measure the critical body joint angles for postural evaluation by using the Kinect's skeletal tracking feature. The body joint angle data of ten volunteers were measured simultaneously by both Kinect and electro-goniometers. The validation analysis was conducted in both static and dynamic domains of application. RESULTS: Minimal variation was observed between the two techniques, and the Kinect correlated well for upper-arm joint angles of 45∘, 60∘ and 90∘; lower-arm joint angles of 30∘, 45∘, 60∘, and 90∘; straight neck position, neck joint angle at maximum possible flexion; straight trunk position, trunk bend angle at full flexion. In dynamic analysis, four out of five ICC values were > 0.75 except for the upper arm. Discrepancies in the results indicated the disapproval of Kinect for only wrist measurements. CONCLUSION: The results of the static and dynamic studies gave a sufficient basis to consider the Kinect tool as an alternative to contemporary posture-based ergonomic evaluation methods.

Clinical Trial to Assess Physiology and Activity of Masticatory Muscles of Complete Denture Wearer Following Vitamin D Intervention.

Background and Objectives: Little information is available on the role of Vitamin D as a micro-nutrient deficiency with masticatory muscle efficiency and its effect on the function of removable prosthesis. The aim of this study was to evaluate the role of vitamin D on masticatory muscle activity among completely edentulous patients and its effect on the retention of removable complete dentures (RCDs). Materials and Methods: A non-randomized clinical control trial was conducted on completely edentulous patients (60.53 ± 7.01 years) in the Indian population between 2017 and 2019. Subjects were evaluated for temporomandibular disorders according to the Diagnostic Criteria for Temporomandibular Disorders (DC/TMD). Serum Vitamin D (S Vit D) levels, Ultrasonography (USG), and surface Electromyography (sEMG) readings of the masseter muscle were recorded at enrolment (Level 0), after 3 months of Vitamin D therapy (Level 3), and after consecutive 3 months of maintenance therapy, i.e., after 6 months from baseline (Level 6). The fabrication of new RCDs was done for all after the enrolment, and the retention of RCDs was assessed by asking a question regarding denture retention and asking respondents to mark their satisfaction on a 5-point Likert scale. Data were analysed using ANOVA, Paired'-test and Pearson correlation coefficients. A p-value less than 0.05 indicated a statistically significant association. Results: Between enrolment and a six-month follow-up, S Vit D levels showed an increase from 16.03 ± 5.68 ng/mL to 31.35 ± 9.28 ng/mL, showing an increase of 15.32 ± 9.38 ng/mL (95.57% rise). Statistically significant values were observed for USG and sEMG. Conclusions: Results showed that S Vit D affects masticatory muscle activity by improving its thickness and boosting its tonicity. Healthy muscles assist in the retention of RCDs, consequently aiding in mastication, speech, and phonetics, hence improving patient satisfaction. Clinical implication: Acknowledging the fact that the prevalence of Vitamin D deficiency is worldwide. We suggest Vitamin D therapy as a nutritional intervention among the elderly completely edentulous population, following dietary counselling, and consider Vitamin D therapy to be an adjunct to nutritional counselling for improving masticatory muscle activity and efficiency, which aids in RCD retention and stability. Consequently, improving oral health-related quality of life for individuals.

Effectiveness of a Single Chair Side Application of NovaMin® [Calcium Sodium Phosphosilicate] in the Treatment of Dentine Hypersensitivity following Ultrasonic Scaling-A Randomized Controlled Trial.

Dentinal hypersensitivity or cervical dentinal sensitivity is one of the commonest clinical problems. The aim of this randomized controlled trial was to evaluate the effectiveness of a single chair side application of 100% pure calcium sodium phosphosilicate (NovaMin®) in reducing dentin hypersensitivity following ultrasonic scaling as evaluated on a visual analogue scale (VAS). The study included 50 subjects who were selected based on an evaluation of dentinal hypersensitivity on a VAS carried out using a metered air blast from a three-way syringe and divided into two groups (n = 25/group); i.e., the test group (Group A) received the NovaMin® paste and the control group (Group B) received a placebo paste made from pumice. All the 50 subjects included in the study were had VAS scores of 3 or more. The NovaMin® powder mixed with distilled water was applied. Dentinal hypersensitivity was reassessed immediately and after 1, 2 and 4 weeks after the procedure. Results showed that the percentage reduction of dentinal hypersensitivity following a single application of NovaMin® in powder form was about 76.38% immediately, 67.72% one week postoperatively, 52.76% two weeks postoperatively and 26.78% four weeks postoperatively. It can be concluded from the results of the current clinical study demonstrated that a single chair side application of NovaMin® in powder form has a significant and immediate reduction in dentinal hypersensitivity, which lasted nearly for four weeks.

Comparison between Restorative Materials for Pulpotomised Deciduous Molars: A Randomized Clinical Study.

AIM: To evaluate and compare the clinical outcomes of Cention-N (CN) and stainless steel crowns (SSCs) as restorations for pulpotomised primary molars, and to study clinical and radiographic outcomes of pulpotomies restored with these materials. METHODS: The study was conducted on 60 pulpotomised molars with occlusoproximal caries. These were randomly divided into two groups and restored with either stainless steel crowns or Cention-N. Clinical performance of restorations and clinical and radiographic success of pulpotomy was examined at 6, 9 and 12 months. RESULTS: The mean scores for marginal integrity deteriorated significantly at 6, 9 and 12 months in both groups but in comparison were insignificant. The mean for proximal contact deteriorated significantly for the Cention-N group, whereas the mean for gingival health deteriorated remarkably for the stainless steel crown group at successive evaluations. No tooth in either group showed secondary caries or discomfort on biting, except for one tooth in Cention-N group which presented with secondary caries. The clinical success rate for pulpotomised molars was 100% for both groups until nine months, although this had reduced by the end of 12 months. Radiographically, the success rate was 79.3% for Cention-N, while it was 86.6% for stainless steel crowns at 12 months. There was no significant difference in clinical and radiographic success between either group. CONCLUSION: Cention-N and stainless steel crowns are comparable for marginal integrity. However, crowns maintain significantly better proximal contacts while Cention-N was notably better for gingival health of the restored tooth. Both materials do not show secondary caries and discomfort on biting and are comparable in clinical and radiographic success of pulpotomy at the end of one year.

Non-surgical management of dens invaginatus type IIIB in maxillary lateral incisor with three root canals and 6-year follow-up: A case report and review of literature.

BACKGROUND: The presence of dens invaginatus (DI) complicates treatment of any tooth, from diagnosis to access cavity and biomechanical preparation and obturation. Reports of successful non-surgical management of DI type IIIB in maxillary lateral incisor are rare. Here, we report such a case, with three root canals and a long follow-up. CASE SUMMARY: A 13-year-old female patient presented with mild pain in the maxillary right lateral incisor (#7) for 10-15 d. On examination, the tooth was slightly rotated, with slight tenderness on percussion and grade I mobility but with no caries, pockets or restorations and non-vital pulp (via vitality tests). Radiographic examination revealed unusual configuration of the tooth's root canals, with an enamel-lined invagination extending to the apex, suggesting the possibility of DI Oehler's type IIIB and a periapical radiolucency. Widening the access cavity lingually revealed one distinct buccal orifice and two distinct palatal orifices; under higher magnification of a dental operating microscope (DOM), the mesio-palatal and disto-palatal orifices were observed as connected by a C-shaped groove. The root canals were prepared with hand K-files following a step-back technique, and obturated using a combination technique of lateral condensation and vertical compaction. At the 6-year follow-up, the patient was asymptomatic, and the periapical radiography displayed significant healing around the apical end of the root. CONCLUSION: Proper knowledge of unusual root canal anatomy is required in treating DI. Conventional methods of root canal treatment can successfully resolve such complex cases, facilitated by DOM and cone-beam computed tomography.

In vitro Results of Scanning Technique on Assessing Cement Thickness and Interfacial Nanoleakage of Luted CAD/CAM-Fabricated Fiber Posts.

BACKGROUND: Fiber posts are broadly used due to their good esthetics and elasticity close to that of dentin, which allows for uniform stress distribution within a root and lowers the possibility of nonrestorable root fractures. AIM AND OBJECTIVES: The study assessed the layer of cement thickness and interfacial nanoleakage of luted fiber posts which were fabricated with CAD/CAM technology following direct scanning of the post space (DS) method, scanning of a polyether impression of the post space (IS), and scanning of a plaster model of the post space (MS). METHODOLOGY: Ninety premolars were chosen randomly and were assigned to three groups according to the scanning technique. Posts were computer designed and milled from experimental fiber-reinforced composite blocks. RESULTS: The mean and standard deviation values of cement thickness, respectively, were: DS 172 ± 39 = m; IS 199 ± 55 = m, and MS MPa 272 ± 81 = m. The fiber posts fabricated following DS technique demonstrated superior performance compared to posts fabricated upon IS and MS, in terms of the post retention. The cement thickness did not differ between DS and IS, whereas in MS group, the cement layer was significantly thicker than in the remaining two groups. The scanning technique did not influence the sealing ability, as all groups showed comparable nanoleakage. CONCLUSION: Fiber posts fabricated following DS technique demonstrated superior performance. Furthermore, scanning technique did not influence the sealing ability, as all groups showed comparable nanoleakage.

Synergistic Effect of Plant Extracts on Endodontic Pathogens Isolated from Teeth with Root Canal Treatment Failure: An In Vitro Study.

BACKGROUND AND OBJECTIVES: This study aimed to evaluate the synergistic antimicrobial activity of extracts obtained from Salvadora persica (Miswak), Commiphora molmol (myrrh) and Azadirachta indica (neem) in combination with commercially available antimicrobial agents: penicillin, tetracycline, ofloxacin and fluconazole on endodontic pathogens such as Enterococcus faecalis, Streptococcus mitis,Actinomyces naeslundii and Candida albicans. MATERIALS AND METHODS: Microbiological samples from the root canals of the teeth undergoing retreatment were taken using sterile paper points kept at full length in the canal for 30 s. The disc diffusion method was used to check the susceptibility of microbes to the plant extracts and antimicrobials by measuring the diameter of the inhibition zones. Against the microbes, minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC)/minimum fungicidal concentration (MFC) of the plant extracts were assessed. The fractional inhibitory concentration index (FICI) was used to estimate the synergistic effect of plant extracts combined with antimicrobials against the resistant endodontic microbes. RESULTS: The findings clearly indicate the effectiveness of all the three plant extracts, Commiphora molmol, Azadirachta indica, Salvadora persica, against all the experimental pathogenic microorganisms except for the ineffectiveness of Azadirachta indica, Salvadora persica against Candidaalbicans. Maximum antimicrobial activity was displayed by Azadirachta indica against Enterococcusfaecalis (MIC = 0.09 ± 1.2 mg/mL, MBC = 0.78 ± 1.25 mg/mL) and the minimum antimicrobial activity was displayed by Commiphora molmol against Actinomyces naeslundii (MIC = 12.5 ± 3.25 mg/mL, MBC = 100 ± 3.75 mg/mL). The best synergy was displayed by Commiphora molmol with fluconazole against Candidaalbicans (FICI = 0.45). CONCLUSIONS: The current study delineates the variable antimicrobial activity of plant extracts against the experimental endodontic pathogenic microorganisms. Plant extracts in conjunction with various antimicrobials can be valuable aids in combating relatively resistant endodontic microorganisms that have been the cause of worry in recent years, leading to failure even in treatment procedures following all required protocols.

Effect of Fluoride Concentration in Drinking Water on Dental Fluorosis in Southwest Saudi Arabia.

This study was intended to evaluate the fluoride concentration in drinking water and its effect on dental fluorosis in Southwest Saudi Arabia. Water samples were gathered rom wells, filtration plants and commercial brands (bottled water) in distinct urban and rural areas of Asir region of the Kingdom of Saudi Arabia (KSA). Overall, 63 water samples were collected from 12 locations and 9 brands of bottled water. ExStik® FL700Fluoridemeter was used in the analysis of water samples for fluoride levels. The total number of screened patients for dental fluorosis, aged between 9 and 50 years, was 1150; among them, 609 were males and 541 were females. Dean's index criteria were used to examine the patients for dental fluorosis. The results revealed that fluoride levels varied between 0.03 and 3.8 ppm. People who drank well water displayed increased fluoride levels (>0.81 ppm). The prevalence of dental fluorosis was established to be 20.43% among the total number of examined patients. The findings of this study show very mild to moderate dental fluorosis prevail among the patients who consume well water in the Asir region.