Indirect Restorations Research Articles

Management of subgingival proximal defects

Deep proximal cavities can be progressively elevated by a restorative procedure known as deep margin elevation (DME), which improves margins for either direct or indirect restorations. Dietschi and Spreafico (1998) introduced the non-surgical alternative procedure of DME for crown lengthening. Other names for the DME concept include “coronal margin relocation,” “proximal box elevation,” and “cervical margin relocation.” A DME treatment’s therapeutic effectiveness depends on a proper indication, and its clinical efficacy is largely dependent on how well the DME is adjusted. In addition to maintaining periodontal health, a suitable DME adaption may be able to lessen bacterial buildup and the occurrence of secondary caries. Here, we report on three cases of DME that were performed when adequate isolation was possible, and caries was progressing subgingivally.

Comparison of the microtensile bond strength of direct and indirect resin restorations in the cervical region

ObjectivesTo evaluate in vitro the adhesion system of direct and indirect composite resin restorations in enamel and dentin, in cavities made in the cervical region using microtensile bond strength (μTBS) and to observe the most recurrent types of failure in the different groups. MethodsStandardized cavities were made in the line of the cementoenamel junction (CEJ) in 36 selected human premolars, which were randomly divided into 2 groups. In the Indirect Restorations (IR) group, indirect restorations were cemented in composite resin, using a universal adhesive and dual resin cement, performing selective enamel etching (SEE). In the Direct Restorations (DR) group, direct restorations were made in composite resin, performing SEE and bonding with the universal adhesive. Each specimen was sliced into sections measuring approximately 1 mm2, with enamel and dentin adhesion divided into subgroups DRe, DRd, IRe, and IRd. The sections were subjected to the μTBS test to assess bond strength in both enamel and dentin, comparing direct and indirect restorations in the cervical region. The types of failure in each group were also observed. ResultsThere was no statistically significant difference in μTBS between the DRe and IRe groups (p = 0.314) and also between the DRd and IRd groups (p = 0.145). There was a predominance of adhesive failures. ConclusionsThe bond strength of composite resin restorations was found to be equivalent in enamel and dentin, whether applied directly or indirectly. There was a predominance of adhesive fractures followed by cohesive resin fractures. Clinical significanceThe choice between direct and indirect restorations in the cervical region may consider patient preferences, but with caution, as clinical factors such as operator skill, specific tooth conditions and case complexity are crucial, and both techniques exhibit comparable bond strength.

Bacterial Adhesion and In Situ Biodegradation of Preheated Resin Composite Used as a Luting Agent for Indirect Restorations.

To evaluate surface roughness and bacterial adhesion after in situ biodegradation of the cementation interface of indirect restorations cemented with preheated resin composite. Resin composite blocks (Z250XT/3M ESPE) were cemented to bovine enamel (7 × 2.5 × 2 mm) using preheated microhybrid resin composites: (1) Filtek Z100 (3M ESPE) (Z100); (2) Gradia Direct X (GC America) (GDX); and (3) Light-cured resin cement RelyX Veneer (3M ESPE) (RXV) (n = 21). The resin composites were preheated on a heating device (HotSet, Technolife) at 69°C for 30 minutes. Disk-shaped specimens (7 x 1.5 mm) were made for biodegradation analysis with the luting agents (n = 25). The in situ phase consisted of 20 volunteers' using an intraoral palatal device for 7 days. Each device had six cylindrical wells for the blocks and the disk-shaped specimens. Biodegradation was evaluated through surface roughness (Ra), scanning electron microscopy (SEM) micromorphological analysis, and colony-forming unit (CFU) count. The film thickness of the luting agents was also measured under stereomicroscopy. Increased surface roughness was observed after the cariogenic challenge without differences between the luting agents. Higher variation and surface flaws suggestive of particulate detachment were observed for Z100. No differences were observed in CFU counts. All materials underwent surface biodegradation, and the surface roughness of the resin cements was similar to or lower than that of the preheated resin composites. The resin composites' film thickness was thicker than that of the resin cement. Clinicians should be aware of these factors when choosing the use of preheated resin composite since it can lead to reduced longevity of the cementation interface and, therefore, restorations.

Survival and Complication Rates of Polymer-Infiltrated Ceramic-Network Single- Tooth Restorations with an Observation Period of up to Three Years.

This study evaluated the clinical performance of a polymer-infiltrated ceramic-network (PICN) material for up to 3 years. Patients (N=286) received 581 indirect restorations as crowns (417), overlays (131), and inlays/veneers (33) fabricated using the PICN (VITA Enamic) by CAD/CAM procedures using intraoral scanning (Cerec Omnicam) and milling systems (Cerec MC XL). The restorations were evaluated annually and in case of complications. Data were analyzed using Kaplan-Meier estimate. Complications were classified as biological or technical failures. Until final recall (mean observation period: 18.3 months) with a dropout rate of 4.8%, 3 biological and 10 technical complications were observed. The overall success rate of the placed restorations was 97.7%. Biological complications included pulpitis and pulp necrosis. Technical complications were debonding (n=7) and fracture (n=3). PICN materials can be used as an alternative to lithium-disilicate or zirconium dioxide for single tooth reconstructions, providing that early failures included debonding and fractures.

PREVALENCE AND QUALITY OF RESTORATIVE STRUCTURES OF PERMANENT TEETH IN CHILDREN FROM LOWLAND AND MOUNTAINOUS AREAS OF THE TRANSCARPATHIAN REGION OVER THE COURSE OF OBSERVATION

Introduction: Treatment of invasive forms of caries involves the removal of demineralized hard tooth tissues and the restoration of anatomical integrity using various types of restorative materials. The choice and conditions of use of these materials have clear indications. However, the durability of restorative structures, even with strict adherence to the algorithm, is not always sufficient, especially among children living in areas with biogeochemical deficiencies. Objectives: The aim of this study was to analyze the prevalence of fillings made from different restorative materials in the permanent teeth of children living in lowland and mountainous geographical areas of the Transcarpathian region and to determine the percentage of defects in restorative structures over time. Methods: For the analysis, 525 medical records of dental patients (form 043) from two geographical areas of the Transcarpathian region were selected, specifically from Uzhhorod, University Dental Clinic LLC, and Rakhiv, the dental office of the Rakhiv District Hospital. The period of dental treatment covered was from 2018 to 2022. Paraclinical content analysis was performed to determine the number of direct and indirect restorative structures and to assess the occurrence of defects and their loss at 6 and 12 months post-treatment. Statistical probabilities and errors were determined using the computer program STATISTICA 6.1. Results. The rates of patient visits for the restoration of indirect restorations of permanent teeth in children living in the mountainous zone differ from those in children from the lowland zone of residence significantly after 6 months (4.0%; 2.1%; p<0.05), and not significantly after 12 months (10.0%; 10.5%; p>0.05). Comparing the incidence of defects, impaired fixation, or loss of various types of restorative structures in permanent teeth in children living in lowland and mountainous areas of the Transcarpathian region, it was found that the most common defects or loss of fillings made of glass ionomer cements occurred both after 6 and 12 months. The percentage distribution of the appearance of defects or loss of restorative structures made in the permanent teeth of children living in the mountainous zone from glass ionomer cements, light-curing composites on indirect restorations is 6 months (7.2%, 6.0%, 4.0%, p>0.05) and 12 months (16.3%, 11.1%, 10.0%, p>0.05). The differences are not significant. In the permanent teeth of children living in the low-lying area, the percentage of defects or loss of restorative structures made of glass ionomer cements, light-curing composites on indirect restorations is 6 months (6.7%, 4.4%, 2.1%, p<0.05) and 12 months (20.0%, 9.6%, 10.5%, p<0.05). The differences are significant. Conclusions: Thus, when comparing the percentage of defects in various restorative structures and their loss in the permanent teeth of children living in the lowland and mountainous areas of the Transcarpathian region, no significant differences were found. Specifically, for glass ionomer cements, the defect percentages were 6.7% and 7.2% after 6 months (p > 0.05) and 20.0% and 16.3% after 12 months (p > 0.05). For direct composite restorations, the defect percentages were 4.4% and 6.0% after 6 months (p > 0.05) and 9.6% and 11.1% after 12 months (p > 0.05). For indirect composite restorations, the defect percentages were 2.1% and 4.0% after 6 months (p > 0.05) and 10.5% and 10.0% after 12 months (p > 0.05). This indicates that the differences in the percentage of defects between the lowland and mountain zones are not statistically significant for any of the types of restorative structures during the specified periods.

Effect of immediate dentin sealing on the fracture strength of indirect posterior restorations:Systematic review and meta-anlysis protocol.

Background Immediate Dentin Sealing (IDS) is a technique that applies an adhesive layer immediately after tooth preparation, prior to the placement of indirect restorations. This method is gaining attention due to its potential to improve the bond strength and mechanical properties of restorations, particularly in the posterior region where restorations endure significant masticatory forces. The objectif of this systematic review and meta-analysis is to evaluate the effect of IDS on the fracture strength of indirect posterior restorations. Methods Following PRISMA guidelines, a comprehensive literature search was conducted in four databases: Web of Science, Scopus, Cochrane Library, and PubMed. Inclusion criteria focused on in vitro studies involving human teeth with indirect posterior restorations, published between 2014 and 2023. Studies using IDS were compared to those using conventional methods. The risk of bias was assessed using the Cochrane Collaboration’s tool, and a meta-analysis was performed with a random-effects model. The standard mean difference and 95% confidence intervals were calculated to compare fracture strength, with I2 statistics assessing heterogeneity. Forest and funnel plots were employed to visualize results and publication bias, respectively. Discussion The results indicate that IDS generally enhances the fracture strength of indirect posterior restorations, particularly with ceramic materials like lithium disilicate. However, the effectiveness of IDS varies depending on the material and restoration type. While some studies demonstrated improved fracture resistance with IDS, others showed minimal benefit, especially with composite restorations. Additionally, IDS improved marginal adaptation and internal fit but increased the risk of severe failures, such as root fractures. Systematic review registration PROSPERO: CRD42024584545 (Registered on 08/09/2024).

The Effects of Different Restoration Materials on the Trueness of Intraoral Scanners

Aim: This study aimed to assess how different restoration materials affect the trueness of intraoral scanners. Materials and Methods: Artificial teeth on a typodont model were prepared for crowns and fixed partial dentures (FPDs) using full metal, monolithic zirconia, and porcelain-fused-to-metal (PFM) materials. Each group underwent 10 scans with a Trios intraoral scanner, generating 60 STL files. A reference scanner created a master model using scanning spray to reduce reflection errors. The STL files were aligned with reverse engineering software for comparison and were analyzed in micrometers (μm) using Root Mean Square (RMS) and Mean Distance measurements. The Levene test and two-way ANOVA with Post Hoc analysis were used for statistical evaluation. Results: The RMS deviations for the FPDs were 77.9 ± 15.2 μm (full metal), 84.6 ± 6.9 μm (monolithic zirconia), and 130 ± 19.7 μm (PFM). For the crowns, the RMS values were 76.9 ± 6.5 μm (metal), 71 ± 8.2 μm (monolithic zirconia), and 153 ± 22.4 μm (PFM). The mean distance deviations for the FPDs were 11.4 ± 4.8 μm (metal), 11.2 ± 3.4 μm (monolithic zirconia), and 18.3 ± 2.6 μm (PFM). For the crowns, the mean distances were 8.6 ± 3.4 μm (metal), 10.2 ± 3 μm (monolithic zirconia), and 24.7 ± 3.3 μm (PFM). Significant differences were noted in the PFM groups. Conclusion: Restoration materials notably affected intraoral scanner trueness, especially PFM restorations. The restoration length did not significantly affect the accuracy.

Options for replacing a single lost anterior tooth in a dentition with reduced periodontal health

To restore comfort, function, and esthetics while maintaining occlusal stability, restoring a single missing anterior tooth in a periodontally impaired dentition is a significant task. An implant-supported crown, traditional three-unit fixed partial denture (FPD), cantilever FPD, resin-bonded FPD, or removable partial denture can be considered in a normal, healthy dentition; however, problems with mobility and poor periodontal support of the remaining dentition may make these procedures unfeasible options as it might be difficult to avoid overloading of the implant in periodontal compromised adjacent teeth, difficult to achieve proper esthetics with conventional FPD, to maintain the stability of dental arch with acrylic resin removable partial dentures is not possible and incidences of frequent debonding of resin bonded FPD are high when abutments are mobiles. Fiber-reinforced composite resin FPD is often effective in these clinical situations to provide a conservative therapy option to restore the patient’s ease and esthetics by limiting mobility.

Performance of large language artificial intelligence models on solving restorative dentistry and endodontics student assessments

ObjectivesThe advent of artificial intelligence (AI) and large language model (LLM)-based AI applications (LLMAs) has tremendous implications for our society. This study analyzed the performance of LLMAs on solving restorative dentistry and endodontics (RDE) student assessment questions.Materials and methods151 questions from a RDE question pool were prepared for prompting using LLMAs from OpenAI (ChatGPT-3.5,-4.0 and -4.0o) and Google (Gemini 1.0). Multiple-choice questions were sorted into four question subcategories, entered into LLMAs and answers recorded for analysis. P-value and chi-square statistical analyses were performed using Python 3.9.16.ResultsThe total answer accuracy of ChatGPT-4.0o was the highest, followed by ChatGPT-4.0, Gemini 1.0 and ChatGPT-3.5 (72%, 62%, 44% and 25%, respectively) with significant differences between all LLMAs except GPT-4.0 models. The performance on subcategories direct restorations and caries was the highest, followed by indirect restorations and endodontics.ConclusionsOverall, there are large performance differences among LLMAs. Only the ChatGPT-4 models achieved a success ratio that could be used with caution to support the dental academic curriculum.Clinical relevanceWhile LLMAs could support clinicians to answer dental field-related questions, this capacity depends strongly on the employed model. The most performant model ChatGPT-4.0o achieved acceptable accuracy rates in some subject sub-categories analyzed.

Prevalence of Decay and Tooth Condition Changes Adjacent to Restored Dental Implants: A Retrospective Radiographic Study.

This study examined the association between a dental implant and changes in adjacent teeth over time. Electronic health records of 1818 patients who received a dental implant were retrospectively evaluated over 14 years (2005-2019) in a university setting. The status of the adjacent tooth and vertical and horizontal distance from the implant platform to adjacent teeth were determined using digital intraoral radiographs taken at baseline and the last follow-up visit (1-14 years, median 4 years). In total, 1085 dental implants were evaluated. There were 234 instances of a change in the adjacent tooth. Decay was observed in 83 (7.6%) of adjacent teeth; the mean time to development was 4 years (range 1-14 years). Approximately 9% of adjacent teeth received direct restorations, 4.8% received indirect restorations, 1% received endodontic root canal treatment, and 5.6% were extracted. The mean horizontal distance between the implant platform and the adjacent teeth was 3.56 mm; the mean vertical distance from the contact point to the alveolar crest on the tooth side was 6.2 mm at the first time of the reported decay on X ray. These distances did not significantly influence the occurrence of caries. The prevalence of interproximal contact loss was higher on the mesial of the implant crown at 63% compared with 20% on the distal side. This large retrospective analysis identified that teeth adjacent to a dental implant were at risk of decay and changes in their condition. In addition, the implant-to-tooth distance and inadequate emergence profile may contribute as caries risk factors in addition to hygiene and a high sugar level diet. These findings appear essential for clinicians when making treatment decisions and discussing outcomes with patients.

On the suitability of photocuring-assisted DIW for manufacturing complex prosthesis from commercial dental composites

A 3-D printing method to produce dental prostheses of complex shapes from a commercial, photocurable resin-ceramic slurry is developed and optimized. The microstructure, mechanical properties and wear behavior of the resulting material are evaluated and compared with a conventional/control sample and other ceramic-polymer dental composites. Commercial resin-ceramic dental slurries can be successfully extruded and appropriately photocured in a low cost 3-D printing system to produce cost-efficient complex dental parts that could be used in indirect restorations. The printing process does not appreciably introduce defects in the material and the 3-D printed composites exhibit mechanical properties (hardness, elastic modulus) and wear resistance comparable to the control material and analogous, conventional dental composites. The main wear mechanisms under sliding contact against a hard antagonist are plastic deformation at the asperity level and ceramic particle pull-out due to filler/matrix interfacial weakness.Graphical 3-D printing commercial resin-filler slurries creates cost-efficient tooth prostheses with properties akin to conventional dental composites

Biomechanical behaviour of tilted abutment after fixed partial denture restoration of CAD/CAM materials

BackgroundFailure to restore missing teeth in time can easily lead to the mesial tilting of the distal abutment teeth. However, a fixed partial denture (FPD) can improve stress conduction and distribution and prevent periodontal injuries. In these more complex cases, it is necessary to consider various factors comprehensively to improve conventional treatment planning and achieve better results.MethodsWe selected a patient with a missing first molar and a mesial inclination of the second molar, leaving inadequate space or bone mass for implant denture restoration, necessitating an FPD for restoration. Three-dimensional finite element analysis (3D-FEA) combined with photoelastic analysis were used to explore how the inclination angle (0 ‒ 30°) and different dental restoration materials (zirconia, lithium disilicate, polymer-infiltrated ceramic network, and resin composite) affect the biomechanical behaviour of FPD‒abutments‒periodontal tissue complex.ResultsThe stress was easily concentrated in the FPD connectors, enamel shoulder collar, periapical area, and root bifurcation. The stress on FPD and the periodontal ligament (PDL) of the second premolar increased with an increase in the elastic modulus of FPD, with an opposite trend in the abutments, the alveolar bone, and the PDL of the second molar. The stress on the FPD and alveolar bone increased with increased inclination angle of the distal abutment. The stress on two abutments and their PDL were positively correlated with the inclination angle in two stages; however, when the inclination angle > 12°, the second premolar and its PDL showed a negative correlation.ConclusionsFPDs can be used for restoration within 24° of distal abutment inclination, but protecting the abutments (< 12° especially) and the periodontal tissue (> 12° especially) must be taken seriously. For this purpose, an FPD material with higher strength is recommended.

Effect of different preparation designs and material types on fracture resistance of minimally invasive posterior indirect adhesive restorations.

To evaluate the impact of various preparation designs and the material type on fracture resistance of minimally invasive posterior indirect adhesive restorations after aging using a digital standardization method. One-hundred sixty human maxillary premolars free from caries were assigned into 16groups (n=10): bevel design on enamel substrate with mesial box only (VEM), butt joint design on enamel substrate with mesial box only (BEM), bevel design on enamel substrate with mesial and distal box (VED), butt joint design on enamel substrate with mesial and distal box (BED), bevel design on dentin substrate with mesial box only (VDM), butt joint design on dentin substrate with mesial box only (BDM), bevel design on dentin substrate with mesial and distal box (VDD), and butt joint design on dentin substrate with mesial and distal box (BDD). Each group was restored with pressable lithium disilicate (LS2) or disperse-filled polymer composite (DPC) materials. Adhesive resin cement was used to bond the restorations. The specimens were aged for 10,000 thermal cycles (5°C and 55°C), then 240,000 chewing cycles. Each specimen was subjected to compressive axial load until failure. A two-way analysis of variance (ANOVA) test followed by a post hoc Tukey test was used to analyze the data (α=0.05). The two-way ANOVA test revealed a significant difference among designs (p<0.001) and materials (p<0.001) with no interaction effect (p=0.07) between the variables. The Post hoc Tukey test revealed that the VEM group exhibited the highest mean fracture resistance value, while the BDM group had the lowest. The LS2 groups showed the highest mean fracture resistance values. The DPC groups showed a restorable fracture pattern compared to the LS2 groups. Bevel and butt joint designs with mesial or distal boxes are recommended for conservative posterior indirect adhesive restorations in premolar areas. Enamel substrate improved load distribution and fracture resistance. DPCs have restorable failure patterns, while pressed LS2 may harm underlying structures.

Comparative Strength Study of Indirect Permanent Restorations: 3D-Printed, Milled, and Conventional Dental Composites.

Background/Objectives: Limited research has been performed to assess the strength of resin-bonded 3D-printed restorations. Based on that, this study investigates the impact of different manufacturing methods on the fracture load of indirect composite restorations (ICRs) following an aging process. Methods: Three manufacturing techniques-conventional (CRC), milled (MRC), and printed (PRC)-were evaluated using 60 specimens, each with a diameter of 10 mm and a thickness of 1.0 mm. Sandblasting with Al2O3 particles was employed to optimize the bonding process, significantly influencing surface roughness parameters (Ra, Rz, RSm). All specimens were bonded to the dentin analog using composite resin cement and subjected to either 10,000 thermocycles (TC) or storage (ST) at 37 °C in distilled water. Fracture load assessments were performed using a universal testing machine. A finite element analysis was conducted to assess stress distribution. Results: Two-way ANOVA results indicated that the manufacturing method significantly affected mean fracture load values (p < 0.001), with PRC showing the highest mean fracture load (4185 ± 914 N), followed by MRC (2495 ± 941 N) and CRC (599 ± 292 N). The aging protocol did not have a significant impact on fracture load. Conclusions: This study revealed that 3D-printed resin composite exhibited comparable strength to milled resin composite when adhesively cemented, suggesting it is a promising option for indirect composite restorations based on its mechanical performance. However, further research is needed to evaluate its bond strength and optimal surface treatment methods to prevent early debonding.

The effectiveness of direct versus indirect restoration techniques following canal therapy

The restoration of endodontically treated teeth is a critical aspect of dental practice, with the choice between direct and indirect restoration techniques being central to optimizing clinical outcomes. Direct restorations, such as composite resins, offer advantages in terms of cost, time efficiency, and preservation of tooth structure. However, their long-term performance, particularly in posterior teeth, may be compromised by issues such as marginal leakage, wear, and discoloration. Indirect restorations, including crowns, onlays, and inlays, provide enhanced durability, fracture resistance, and aesthetic outcomes, particularly for teeth that have undergone significant structural loss. These restorations, often made from ceramics or metals, offer superior longevity but come with higher costs and longer treatment times. The aesthetic performance of restorations plays a significant role in patient satisfaction. While direct restorations allow for immediate aesthetic adjustments and are generally more affordable, they may suffer from discoloration and wear over time. Indirect restorations, particularly porcelain-based options, offer better color stability and natural appearance, making them a preferred choice for patients with high aesthetic demands. Cost-effectiveness is another critical factor influencing clinical decision-making. While direct restorations are more affordable initially, their long-term cost-effectiveness may be compromised by the need for repairs or replacements. Indirect restorations, despite their higher upfront cost, often prove to be more economical in the long run due to their durability and reduced need for maintenance. The decision between direct and indirect restoration techniques should be individualized, considering factors such as tooth location, the extent of damage, aesthetic requirements, and financial constraints. A comprehensive evaluation of these factors, along with clear communication with the patient, is essential for achieving optimal clinical outcomes. Indirect restorations generally offer better long-term performance, particularly for heavily compromised teeth, while direct restorations remain a viable option for cases where cost and time efficiency are prioritized.

Enhancing the Opacity of Glass Ceramics by Applying Opaque Stains to the Intaglio Surface.

The aim of this study was to assess the effect of opaque stain application to the intaglio surface of lithium disilicate glass ceramics on the masking ability of discolored substrates and bond strength to a resin-based luting agent (depending on etching time); the stain film-thickness was also assessed. Ceramic specimens were produced with CAD-CAM blocks of lithium disilicate (IPS e.max CAD). Two opaque stains were tested at ceramic intaglio surface: opaque glassy stain for titanium frameworks (OP-ti) and low-fusion glassy stain for ceramic characterization (LFG-iv). Non-stained ceramic specimens served as controls. For optical and colorimetric analyses, A2-shaded ceramics of medium and low-translucencies were tested, in thicknesses of 1.0- and 1.5-mm (n = 10), with two coupling agents (non-shaded-glycerin and A2-shaded try-in paste). CIEDE2000 formula was used for calculation of translucency parameter (TP00) and color differences (ΔE00). Whiteness index for dentistry (WID) was also reported. ΔE00 were assessed over discolored substrates (tooth-shaded A2-reference, A4, C3, and C4; coppery metal, silvery metal, white zirconia, and PEEK). Microshear bond strength of stained and non-stained ceramic specimens to a resin-based luting agent was evaluated. Film-thickness of stains was assessed by scanning electron microscopy. The application of opaque stains to the intaglio surface of lithium disilicate ceramics resulted in significant reduction of TP00 (p < 0.001) and WID (p < 0.001) and differences in L*, C*, and ho color coordinates (especially with OP-ti) (p < 0.001). ΔE00 was significantly reduced in stained ceramic groups in comparison with the control, for all discolored substrates (p < 0.001). Acceptable color matching was obtained with stained ceramic specimens for all discolored substrates, depending on the type of stain, ceramic thickness, ceramic translucency, and coupling agent. The application of stains to the ceramic intaglio surface was not detrimental to bond strength to a resin-based luting agent, but depended on the time of hydrofluoric acid-etching (20 s for OP-ti and 60 s for LFG-iv) (p < 0.001). Film-thickness of stains presented mean values <70 μm. The application of opaque stains to the intaglio surface of lithium disilicate glass ceramics was effective to mask severely discolored substrates, presenting adequate bond strength to the luting agent and thin film-thicknesses. For indirect restorations over severely discolored substrates, the application of opaque stain to the intaglio surface of lithium disilicate glass ceramic ensures acceptable color matching, with adequate bond strength to resin-based luting agents and clinically acceptable stain film-thickness.

Silica infiltration as a strategy to overcome zirconia degradation

The excellent clinical performance of yttria-partially stabilized zirconias (Y-SZs) makes them promising materials for indirect restorations. However, the Y-SZ phase stability is a concern, and infiltrating Y-SZs with a silica nanofilm may delay their degradation processes. In this study, we analyzed stabilities of silica-infiltrated zirconia surfaces after exposure to artificial aging (AA).Four zirconia materials with different translucencies (n = 40) were used, including low translucency 3 mol% Y-SZ (3Y-LT, Ceramill ZI, Amann Girrbach); high translucency 4 mol% Y-SZ (4Y-HT, Ceramill Zolid); and two high translucency 5 mol% Y-SZs (5Y-HT, Lava Esthetic, 3M and 5Y-SHT, Ceramill Zolid, FX white). Sintered specimens were exposed to 40 cycles of silica (SiO2) through room temperature atomic layer deposition (RT-ALD) using tetramethoxysilane (TMOS) and ammonium hydroxide (NH4OH). AA was applied for 15 h in an autoclave (134°C, 2 bar pressure). Stabilities of zirconia-silica surfaces were characterized in terms of hardness and Young's modulus using nanoindentation techniques and crystalline contents using x-ray diffraction (XRD) analyses. Silica deposition was also characterized by X-ray photoelectron spectroscopy (XPS).There was a significant effect of the interaction of materials and surface treatments on the hardness and Young's modulus values of zirconia-silica surfaces (p < 0.001). Silica deposition on zirconia surfaces improved the material resistance to degradation by AA.

ORAL HEALTH AND THE NEED FOR DENTAL CARE IN A GROUP OF PATIENTS FROM OLTENIA

(1) Background: Oral diseases are a major health burden in many countries and affect people throughout life, causing pain, discomfort, changes in facial physiognomy, and even death. The aim of the study was to determine dental treatment needs in a group of patients from Oltenia; (2) Methods: The retrospective study included 813 people, 341 men and 472 women, aged 6-93 years, presented for diagnosis and dental treatment between 2008-2018. The dental records of patients were used to evaluate the state of oral health, and the treatment needs of the patients. Data were collected and stratified into a database in Excel Windows (3) Results: Dental treatment needs included: oral health education sessions (33%), periodontal treatment (30.62%), fillings or other types of direct or indirect dental restorations (20.04%), including endodontic treatments, non-carious lesions treatment, extractions (27.42%), prosthetic restorations (71.83%), of which 10.08% complete dentures or overdentures with tooth or implant support and 43.9% partial dentures or bridges with tooth or implant support. (4) Conclusions: Social factors (socio-economic status and education of the population) and behavioral factors (diet and dental hygiene) have a great influence on dental health status.

A Literature Review of Adhesive Systems in Dentistry: Key Components and Their Clinical Applications

The central aim of adhesive dentistry is to improve the compatibility between current adhesives and a range of substrates by employing diverse application techniques. Therefore, the overarching objective of this review is to offer a comprehensive analysis of dentin bonding systems, starting with an introduction to adhesion and a detailed overview of enamel and dentin structures, their histology, and the impact of dentin structure on resin–dentin bonding. It covers the mechanisms of resin–dentin bonding, including resin adhesive application, bonding mechanisms, and factors influencing efficacy. Further, this review explores the composition of resin adhesive systems, including acidic components, cross-linking monomers, solvents, and other critical elements. It also examines various adhesive strategies—etch-and-rinse, self-etch, and universal adhesives—highlighting their applications and advantages. The review extends to clinical applications of dental adhesion, including direct restorations, indirect restorations, and immediate dentin sealing (IDS), demonstrating the practical implications of adhesive systems in enhancing restoration longevity and performance. In conclusion, despite significant advancements, no gold-standard method for optimal adhesion exists. Each adhesive system has distinct strengths and limitations. The review emphasizes the importance of evaluating methods for achieving durable adhesion and staying current with technological advancements in adhesive systems. Summary: This review provides a thorough analysis of dentin bonding systems, delving into the structures and bonding mechanisms of both enamel and dentin. By exploring various adhesive systems and their components, it highlights the ongoing challenges in achieving optimal resin–dentin adhesion. The review also addresses the clinical applications of dental adhesion, including direct restorations, indirect restorations, and immediate dentin sealing (IDS), illustrating how different adhesive techniques impact clinical outcomes. It underscores the necessity for continuous innovation and assessment of adhesive systems to enhance long-term bonding effectiveness in clinical practice.

Effect of Prosthetic Material and Support Type on Stress Distribution of Fixed Partial Dentures: A Finite Element Study

Choosing an appropriate prosthetic material for the superstructure of an implant-supported or tooth-implant supported fixed partial denture (FPD) is crucial for the success of the prostheses. The objective of this study was to examine the effect of prosthetic material type and tooth-to-implant support on stress distribution of FPDs using three-dimensional finite element analysis (3D FEA). Two FEA models were generated, distinguished by their support configurations: Model I representing an FPD supported by implants, and Model II depicting an FPD supported by both a tooth and an implant. Two different restorative materials, porcelain-fused-to-metal (PFM) and monolithic zirconia, were evaluated for stress distribution under axial and oblique loads of 300 N applied to the pontic. Under both axial and oblique loading conditions, the maximum von Mises stress values were observed to be higher in the implant-abutment complex of both zirconia implant-supported and tooth-implant-supported FPDs compared to PFM FPDs. In the case of axial loading, comparable stress values were found in the cortical bone for PFM (12.65 MPa) and zirconia implant-supported FPDs (12.71 MPa). The zirconia tooth-implant-supported FPD exhibited the highest stress values in the implant-abutment system.