Comparisons of student comprehension of 3D-printed, standard model, and extracted teeth in hands-on sessions

INTRODUCTION

Cavity preparation and direct and indirect pulp capping are difficult processes to learn in dentistry. Although plastic teeth are used in universities in Turkey, the standard model does not teach students how to distinguish between dental hard tissues from caries and how this relates to the pulp. The aim of this study was to investigate the differences in learning when a three-dimensional (3D)-printed tooth was employed in comparison with the standard model and extracted teeth. The differences are evaluated in the design, feasibility, and contribution of the 3D-printed dental tooth in pre-clinical education.

MATERIALS AND METHODS

The multi-layer 3D-printed tooth's authentic design and replication of the dental hard tissues and carious lesions are explored with 55 students for pre-clinical education, which includes caries excavation and direct and indirect pulp capping. The students completed questionnaires evaluating the 3D-printed teeth through comparison with the plastic and extracted teeth, rated with scores from 1 to 11 (1: poorest conformity; 11: excellent conformity).

RESULTS

The questionnaire results indicated that students approved the printed tooth model for the practice of theoretical knowledge and the model received ratings between good and excellent. The results were statistically analysed using the Wilcoxon signed-rank test, and the printed teeth had the highest approval from the students (p < .001).

CONCLUSION

The results of this study demonstrated that the use of the designed 3D-printed tooth is preferred by the students based on their perception of learning cavity preparation and pulp capping in a pre-clinical environment. Workflow and production were cost-effective with the use of 3D printing technology. The printed tooth allowed students to gain realistic experience before treating patients.

Association between stereoacuity and simulated clinical performance among dental students: an exploratory investigation

INTRODUCTION

Dentistry is a profession that requires a high level of the hand-eye coordination. Although considerable attention has been put on dental students' manual dexterity, little emphasis was made on students' visual competency as a variable influencing their competency. In this study, we aimed to assess the association between dental students' stereopsis and their pre-clinical performance.

METHODS

Dental students (n = 49) were required to perform the porcelain-fused-to-crown preparation for a lower first molar and an upper central incisor plastic teeth mounted on phantom heads. Performance was assessed by two faculty members based on two rubrics, which collectively included 11 assessment criteria. Afterward, students undertook a stereoacuity test using Randot stereotest. Stereopsis values greater than 40 arc/s were considered abnormal.

RESULTS

A significant negative correlation was seen between stereopsis scores and students' grades for the upper incisor (p < 0.01), but not for the lower molar. An association was also seen between abnormal stereopsis and students' poor performance in preparing the finish line of the incisor tooth (p = 0.024).

CONCLUSION

Abnormal stereopsis can impact dental students' performance, particularly when preparing teeth indirectly using a dental mirror. Dental educators should give attention to students' stereoacuity, in a manner similar to that given to students' manual dexterity.

Effect of Immediate Dentin Sealing on the Bonding Performance of Indirect Restorations: A Systematic Review

The popular immediate dentin sealing (IDS) technique is used to improve the bond strength of indirect restorations. This systematic review assessed whether bond strength is affected by the type of aging conditions, bonding agents, flowable resin composites, impression materials, temporary materials, and/or resin cement used within the IDS procedure. A comprehensive database search of PubMed, Embase, Scopus, Ovid Medline, Web of Sciences, Cochrane Library, Dentistry & Oral Sciences Source, and ProQuest was carried out up to 30 January 2024 without publication year or language limitations. Only in vitro full-texts regarding the effect of IDS on bond strength were included, and the quality of their methods was assessed via a Risk of Bias (RoB) test. In total, 1023 pertinent studies were initially found, and 60 articles were selected for review after screening for the title, abstract, and full texts. IDS application improves the bond strength of indirect restorations to dentin and reduces the negative effects of temporary materials on the bond durability of final indirect restorations. Filled dentin bonding agents or combinations with flowable resin composite are preferred to protect the IDS layer from conditioning procedures.

The Impact of a Web-Based Restorative Dentistry Course on the Learning Outcomes of Dental Graduates: Pre-Experimental Study

BACKGROUND

Restorative dentistry plays a crucial role in dental practice, necessitating professionals to stay abreast with the latest advancements in the field. The advancement of technology has made web-based learning a widely used method of education delivery in dentistry, providing learners with extensive information and flexibility.

OBJECTIVE

This study aims to evaluate how effective an online educational course in restorative dentistry is for dental graduates in Syria.

METHODS

This study used a pre-experimental study design, with pretest and posttest assessments to measure changes in participants' knowledge and skills. A total of 21 dental graduates completed the online course in restorative dentistry, which was hosted on Moodle, using the learning management system of the Syrian Virtual University. Participants were provided with a suggested learning sequence and had the flexibility to navigate the course on their own and at their own pace. The course was developed based on the principles of web course design and web-based course development using the ADDIE (Analysis, Design, Development, Implementation, and Evaluation) general instructional design model. The pretest and posttest assessments consisted of 50 multiple-choice questions with a single correct answer, aligning with the course content. Furthermore, participants were asked to complete a course acceptance survey upon finishing the course.

RESULTS

The results showed a significant improvement in the participants' knowledge of restorative dentistry, supported by a statistically significant P value of less than .05. The effect size of the difference between the pre and posttest indicated that the effect size, as indicated by ω2, demonstrated a significant 62.1% difference between the pre and posttest, indicating a high and statistically significant effect. Furthermore, the value derived from the Haridy obtained work ratio formula indicated that the educational program was effective, with an effectiveness amount of 3.36%. Additionally, 93% (n=19) of respondents expressed confidence in having gained the expected benefits from the educational course upon its completion.

CONCLUSIONS

The findings indicated a notable enhancement in the participants' understanding of restorative dentistry. The participants' high satisfaction rate and positive feedback from the course acceptance survey further emphasize the favorable reception of the web-based learning approach. This study highlights the potential of web-based learning in dental education, opening the door for future research in this area. The findings of this study carry important implications for the design and implementation of web-based educational programs in dentistry, suggesting that such programs can serve as an effective tool for continuous professional development in the field.

A Comparative In Vitro Analysis of Antimicrobial Effectiveness and Compressive Strength of Ginger and Clove-Modified Glass Ionomer Cement

Background Glass ionomer cement (GIC) is widely recognized for its self-adhesive characteristics and biocompatibility, making it commonly used as a restorative material. However, challenges related to limited antibacterial effectiveness and relatively low mechanical properties have hindered its widespread clinical use. Clove and ginger are recognized for their potent antimicrobial activity against numerous pathogenic microorganisms. The present study aims to enhance the clinical applicability of GIC by modifying it with clove and ginger extract. Aim The objective of the study is to assess the antimicrobial effectiveness and compressive strength of GIC modified with ginger and clove extract. Materials and methods Ginger and clove extracts were prepared and incorporated into conventional GIC at three concentrations for each, creating ginger-modified GIC groups (Group A, Group B, and Group C) and clove-modified GIC groups (Group D, Group E, and Group F), with Group G as the control (conventional GIC without modification). The antimicrobial assessment was conducted on disc-shaped GIC specimens (3.0 mm height x 6.0 mm diameter) prepared using molds. Bacterial strains were used to evaluate antimicrobial properties, with minimum inhibitory concentration (MIC) assays conducted at intervals of one to four hours for both modified and unmodified groups. Compressive strength specimens were prepared using cylindrical molds (6.0 mm height × 4.0 mm diameter), according to the ISO (International Organization for Standardization) guidelines. The evaluation was conducted using a Zwick universal testing machine (ElectroPuls® E3000, Instron, Bangalore, India), with the highest force at the point of specimen fracture recorded to determine compressive strength. Statistical analysis was conducted utilizing a one-way analysis of variance (ANOVA) alongside Tukey's post hoc test, with a significance threshold set at p < 0.01. Results The antimicrobial effectiveness of clove and ginger-modified GIC was assessed through a MIC assay, revealing a statistically significant improvement in antimicrobial potency against Streptococcus mutans and Lactobacillus within the modified groups compared to the control group (p < 0.01). Increased extract concentration correlated with enhanced antimicrobial activity. Clove-modified GIC exhibited superior antimicrobial efficacy compared to ginger extract. Compressive strength was higher in clove-modified GIC groups (p < 0.01), with Group F showing a maximum value of 175.88 MPa, while other modified groups demonstrated similar results to the control, with a value of 166.81 MPa (p > 0.01). Conclusion The study concludes that both clove-modified GIC and ginger-modified GIC exhibited antimicrobial activity against Streptococcus mutans and Lactobacillus species. The antimicrobial activity was notably higher in clove-modified GIC compared to ginger-modified GIC. Additionally, the compressive strength of clove-modified GIC surpassed all other groups. Thus, clove-modified GIC emerges as a promising restorative material for addressing recurrent caries. Future investigation is necessary to assess the long-term durability of the material.

Comparative Evaluation of Antimicrobial Effectiveness and Compressive Strength in Neem and Lemongrass-Modified Glass Ionomer Cement: An In Vitro Study

Background Glass ionomer cement (GIC) demonstrates biocompatibility and fluoride ion release, indicating their potential to inhibit a wide range of bacteria, although this remains uncertain. Lemongrass and neem are recognized for their potent antimicrobial activity against numerous pathogenic microorganisms. The objective of the study is to evaluate the antimicrobial effectiveness and compressive strength of GIC modified with neem and lemongrass. Methodology Lemongrass and neem were incorporated into conventional GIC at varying concentrations. Group I - neem-modified GIC (0.5%, 1%, 2%), group II - lemongrass-modified GIC (0.5%, 1%, 2%), and group III (non-modified GIC as a control group). The disk-shaped specimens were then compared to unmodified GIC (control). Antimicrobial effectiveness was assessed using the minimal inhibitory concentration (MIC) assay against Streptococcus mutans and Lactobacillus. Compressive strength was assessed using a Universal Testing Machine, with a crosshead speed set to 0.5 mm per minute. Statistical analysis was conducted with a significance level set at p < 0.05. Results Neem modification displayed superior antimicrobial effectiveness against both Streptococcus mutans and Lactobacillus at all concentrations when compared to the control, with 2% showing the least mean value of 0.262. In contrast, lemongrass modification exhibited a significant difference in effectiveness against Streptococcus mutans but no difference against Lactobacillus. Neem modification demonstrated superior performance compared to lemongrass (p < 0.05). Both modified groups showed no significant impact on compressive strength. Conclusions Neem-modified GIC demonstrated the highest antimicrobial efficacy against Streptococcus mutans and Lactobacillus without altering its compressive strength. This suggests its potential as a promising alternative material in restorative dentistry. Additional in vivo investigations are needed to assess the extended-term effectiveness of the material.

Color match of single-shade restorations after professional dental bleaching: An in vitro study

Background

Restorative dentistry aims to reproduce natural tooth shades through resin composites that must be layered to obtain colors, opacities, and translucencies, and therefore, clinical success is operator skill dependent.

Aims

The purpose of this study is to evaluate the color shift of single-shade composite restorations before and after dental bleaching.

Materials and Methods

Eighty human extracted posterior teeth were restored with four single-shade composites (Omnichroma OM; Clearfil Majesty ES-2 Universal CL; Essentia Universal ES; Venus Diamond One VE) (n = 20 each). Standardized V class cavities were prepared on buccal side. VITA Easyshade V spectrophotometer was used to register VITA color and color coordinates 24 h before (T0), 24 h after (T1), and 1 week after (T2) dental bleaching (Opalescence Boost PF 40%). Color differences (ΔEab) and (ΔWID) were calculated and subjected to statistical analysis.

Statistical Analysis

Categorical variables were analyzed using Pearson Chi-square, and data from color coordinates were analyzed using one-way analysis of variance and Tukey's multiple comparison test with Bonferroni correction. Paired t-tests were performed to compare continuous measures between groups and treatment time.

Results

Instrumental evaluations revealed statistically significant differences between materials (P < 0.05) with lower values for ES and VE samples followed by CL and OM at T0 and T1. At T2, OM and CL ΔEab values decrease getting closer to ES and VE.

Conclusion

Single-shade composites seem to match with the surrounding bleached tooth.

Investigating the Potential of Acacia nilotica-Enriched Glass Ionomer Cement: An Analysis of Antimicrobial Activity and Compressive Strength

Background According to existing literature, introducing natural antibacterial agents into glass ionomer cement (GIC) has been associated with potential negative impacts on their strength properties. Hence, this study aims to explore the antibacterial effectiveness of glass ionomer cement enriched with Acacia nilotica and subsequently assess its compressive strength characteristics. Aim The objective of the study is to assess the antimicrobial effectiveness and compressive strength of glass ionomer cement modified with Acacia nilotica. Materials and methods  The plant extract was incorporated into the conventional glass ionomer cement in three different proportions (powder GIC: extract: liquid GIC), divided into group I, group II, and group III with ratios of 2:1:1, 3:1:2, and 3:2:1 respectively. Additionally, a control group denoted as group IV was included without any modifications. Subsequently, the specimens were prepared, and their chemical structure was analyzed using Fourier transform infrared spectroscopy (FTIR), followed by testing for antimicrobial activity using the minimum inhibitory concentration (MIC) assay against Streptococcus mutans and Lactobacillus. The assessment of compressive strength was conducted following ISO 9917-1:2007 standards, and the recorded values represent the maximum force the specimen could withstand before fracturing. Results The antimicrobial effectiveness against Streptococcus mutans and Lactobacillus exhibited a notable increase in all modified specimens compared to the control group, with a significance level of p<0.05. Additionally, significant improvements in compressive strength were observed in group III (183.49±2.99) when compared to the remaining groups. The higher concentrations of the plant extract resulted in superior outcomes. Conclusion Therefore, the incorporation of Acacia nilotica into GIC shows promising potential as a restorative material. These investigations can provide valuable insights into the material's performance and durability, contributing to its potential application in dental restorations. Future research is needed to thoroughly investigate the bonding chemistry between Acacia nilotica and GIC, as well as to assess the extent of microleakage.

Agenesis of the maxillary permanent lateral incisors with the deciduous retained: Conservative and biomimetic approach using the BAIR technique

OBJECTIVE

Agenesis of the maxillary permanent lateral incisors is a condition that requires treatment aimed at improving the esthetics, even at an early age. However, traditional therapeutic protocols are long, invasive and have limitations and contraindications imposed by the age of the patient.

CLINICAL CONSIDERATIONS

Recent developments in restorative dentistry have provided a new approach to this clinical situation, in particular when the deciduous laterals are retained. We report two cases regarding the management of missing lateral incisors using Biologically Active Intrasulcular Restoration (BAIR) technique. The BAIR technique allows us to transform the shape of the deciduous lateral incisor into the permanent, acting both on the dental morphology and proportions, and on the appearance of the soft tissues and the gingival parables.

CONCLUSIONS

The BAIR technique is a valid approach to cases of agenesis of the maxillary permanent lateral incisors, when the deciduous are retained. It does not require any preparation of the dental tissues, is reversible and minimally invasive. It is applicable to patients of all ages, and results are obtained in a single appointment.

CLINICAL SIGNIFICANCE

The BAIR technique allows a biomimetic conservative approach for the rehabilitation of congenitally missing permanent lateral incisors, when the deciduous are retained. It is a non-invasive protocol and effective in successfully restoring esthetics.

Myocentric relation in an additive esthetic rehabilitation within a fully digital workflow

In recent years, tooth wear has been a growing concern in dentistry as it has become increasingly prevalent among the population. At the same time, the development of adhesive techniques has enabled minimally invasive treatment protocols, with the goal of preserving and protecting teeth for as long as possible. This clinical report presents the case of a full-mouth rehabilitation patient with tooth wear who was treated using minimally invasive techniques. Esthetic and functional outcomes were designed and monitored using digital tools such as digital impressions, 3D facial scans, a digital tooth library, transcutaneous electrical nerve stimulation (TENS), MRI, and kinesiographic (KS) analysis throughout the treatment. To increase the vertical dimension of occlusion, instead of using traditional centric relation (CR) methods, a myocentric relation (MCR) technique was employed. This approach allowed the clinician to maintain the occlusal Class I situation, avoiding more invasive orthodontic treatment or maxillofacial surgery and resulting in reduced morbidity, treatment time, and cost for the patient. At the 1-year follow-up, good patient adaptation was shown, suggesting that the MCR concept is a viable alternative to conventional CR methods in appropriate cases.

Extended porcelain veneers in the maxillary anterior region. A retrospective study with an up to 27-year follow-up

AIM

The aim of the present retrospective study was to evaluate the long-term results, including technical and biologic outcomes, of maxillary extended porcelain veneers with an incisal edge thickness above 2 mm.

MATERIALS AND METHODS

Patients treated with extended porcelain veneers performed by a single clinician at University of Geneva between 1990 and 2003 were identified and invited to an examination. Of the 37 identified patients, 10 patients with 50 veneers agreed to be examined and were included. A clinical examination was performed to assess survival rates as well as technical and biologic outcomes (modified United States Public Health Services criteria). Patient records were also reviewed to retrieve patient and reconstruction data and every complication event. Patient-reported outcome measures (PROMs) were evaluated using a visual analog scale to measure esthetic satisfaction, functional and phonetic comfort, masticatory improvement, tooth sensitivity, and acceptance of restoration replacement in case of failure. Data were descriptively analyzed, and Kaplan-Meier survival estimators were computed for survival rates and complication events.

RESULTS

The survival rate of the veneers was 96% after a mean follow-up of 20.7 ± 3.7 years in function. The technical complication rate amounted to 30%, including two failures, nine repairable fractures, three cracks, and one displacement due to trauma. No cavitated caries lesions or endodontic complications were registered. PROMs were very high for esthetic satisfaction and phonetic comfort.

CONCLUSIONS

Within the limitations of the present retrospective study, extended porcelain veneers appear to be a successful long-term treatment option in terms of clinical outcomes and patient satisfaction.

Clinical guidelines for posterior restorations based on Coverage, Adhesion, Resistance, Esthetics, and Subgingival management. The CARES concept: Part III – subgingival margins, “ferrule” design, and posts in severely compromised teeth

Despite the clear advances regarding the restoration of posterior teeth, especially with the minimally invasive approach, there are still several topics where the available scientific evidence does not provide clear answers in terms of clinical decisions. The indications, differences, and clinical protocols for partial adhesive restorations (onlays, overlays, and endocrowns) and resistance form restorations (full-contour resistive crowns) were presented in Parts I and II of the present article series based on Coverage of susceptible cusps, Adhesion advantages and limitations, Resistance forms to be implemented, Esthetic concerns, and Subgingival management - the CARES concept. Now, in Part III, the focus is on different approaches of managing subgingival areas, gaining "ferrule" design, and the role of posts on the restorability strategies of severely compromised teeth.

Properties of Nanohybrid Dental Composites-A Comparative In Vitro Study

(1) Background: the current study investigated three nanohybrid composites: two commercial products ClearfilMajestyTM (CM) and HarmonizeTM (HU), compared with an experimental product PS2. (2) Methods: Two sample types were molded using Teflon dies. The first sample type was represented by standard discs (20 mm diameter and 2 mm thickness) (n = 60, 20/each material), used for surface conditioning investigation, specifically roughness monitoring and color stability analysis using AFM and the CIELab test, respectively. The second sample type was a standard cylindrical specimen (4 mm diameter and 6 mm height) for compression testing (n = 60, 20/each material). After complete polymerization, the samples were ground with sandpaper and further polished. The filler size and distribution in the polymer matrix were investigated with SEM. Data were statistically analyzed using the Anova Test followed by Tukey's post hoc test on the Origin Lab 2019 software produced by OriginLab Corporation, Northampton, MA, USA. (3) Results: A mono-disperse system was identified in HU samples, while CM and PS2 revealed both nano- and microfiller particles. The samples' observation after immersion in coffee and tea indicated that a lower roughness combined with optimal filler lamination within the polymer matrix assured the best color preservation. The compression strength was lower for the HU sample, while higher values were obtained for the complex filler systems within CM and PS2. (4) Conclusions: the behavior of the investigated nanohybrid composites strongly depends on the microstructural features.

Deep Margin Elevation - A Retrospective Clinical Study

PURPOSE

The aim of this retrospective study was to assess the short- to mid-term restorative and periodontal outcome of deep margin elevation (DME) performed using resin composite.

MATERIALS AND METHODS

Twenty-eight teeth treated with DME and indirect adhesive restorations were followed-up for a mean of 25.4 months (minimum: 12 months). Clinical and radiographic examination assessed the adaptation of the DME material and indirect restorations, presence of recurrent caries or discoloration, periodontal health at DME and non-DME sites, and periapical health.

RESULTS

The overall success rate was 96.6%. One tooth showed signs and symptoms of apical pathology after 34 months following DME. No caries, discoloration, or periodontal pockets were detected in any of the treated teeth. DME had no detrimental effect on the gingival/periodontal health or plaque accumulation. There was no correlation between the distance from the DME material to the marginal bone level and pocket depth, gingival inflammation, and plaque accumulation (p > 0.05).

CONCLUSION

Deep margin elevation might be considered a safe procedure for teeth with deep subgingival proximal caries in the short- and mid-term.

A Comparative In Vitro Analysis of Antimicrobial Effectiveness and Compressive Resilience in Chirata and Terminalia arjuna Modified Glass Ionomer Cement

BACKGROUND

Glass ionomer cements are commonly utilized in dental restorations due to their biocompatibility, strong chemical bond with dental tissues, and ability to resist tooth decay. However, their effectiveness can be compromised by the presence of persistent cavity-causing microorganisms. Therefore, it is essential to consider incorporating antibacterial agents into these restorative materials. Swertia chirayita (S. chirayita) and Terminalia arjuna (T. arjuna) are well-known for their rich composition of phytochemicals that can potentially inhibit the growth of bacteria. Hence, the current research is focused on modifying glass ionomer cement with Chirayita and T. arjuna extracts to enhance its antibacterial properties.

AIM

This research aims to determine the antimicrobial efficacy and compressive strength of glass ionomer cement modified with Chirayita and T. arjuna extracts.

METHODOLOGY

Plant extracts were prepared from both Chirayita and T. arjuna. The powder and liquid components of conventional glass ionomer cement (GIC) were mixed, followed by adding these extracts at three different concentrations. To assess antimicrobial properties, typical strains of Streptococcus mutans and Lactobacillus were employed to test both the modified GIC and unmodified GIC (used as a control). For Chirayita and T. arjuna-modified GIC, minimum inhibitory concentration (MIC) assays were conducted at three different concentrations. MIC was assessed at various time intervals ranging from 1 to 4 hours for modified and unmodified groups. Moreover, compressive strength was measured using cylindrical molds. The highest force exerted at the point of specimen fracture was recorded to calculate the compressive strength values in megapascal (MPa).

RESULTS

The antimicrobial efficiency of Chirata and T. arjuna-modified GIC was evaluated using a MIC assay, indicating a statistically significant enhancement in antimicrobial potency against S. mutans and Lactobacillus within the modified groups in contrast to the control group (p<0.05). However, there were no notable changes in compressive strength when comparing the control group to the modified groups (p>0.05).

CONCLUSION

The antimicrobial effectiveness against S. mutans was observed to be greater in both T. arjuna and Chirayita-modified GIC. In the case of Lactobacillus, Chirayita-modified GIC exhibited more pronounced antimicrobial properties compared to T. arjuna. Importantly, both extracts did not alter the compressive strength of Conventional (unmodified) GIC. Hence, Chirayita-modified GIC appears to be a promising restorative material for combatting recurrent caries. Additional investigation is required to assess the material's stability over an extended period.

Chewing performance of patients with worn dentition before and after restorations: A scoping review

BACKGROUND

Tooth wear is a multifactorial complex process related to the loss of dental tissue, due to chemical or mechanical processes, by abrasion, attrition, erosion. Restorative treatment represents an attempt to rebuild and recreate the lost structure.

OBJECTIVE

This scoping review aims to investigate whether restorative treatment of worn dentition (either with direct or indirect adhesive composite adhesive procedures or with prosthetic techniques) can have an impact on the masticatory performance parameters.

METHODS

A scoping review was conducted on multiple databases (Pubmed, Medline CENTRAL, ICTRP), following the PRISMA guidelines. Abstracts of research papers were screened for suitability, and full-text articles were obtained for those who satisfied the inclusion and exclusion criteria.

RESULTS

Only one article meet the inclusion criteria of the review. Restorative treatment of worn dentition although have a positive impact on the self-report ability to chew, has no effect on the masticatory performance test.

CONCLUSION

At the moment, not enough evidence to comment on the actual therapeutic role of restorative treatment on tooth wear is available. Clinicians, before taking any clinical decision, should carefully discuss with patients the needs and expectations of the treatment plan.

Zirconia restoration types, properties, tooth preparation design, and bonding. A narrative review

OBJECTIVE

The purpose of this review was to provide dental professionals with information regarding the various types of zirconia restorations, their mechanical and optical properties, tooth preparation design, and bonding protocol in an effort to enhance the longevity and durability of zirconia restorations.

OVERVIEW

The yttria content of zirconia ceramics determines their classification. The mechanical and optical properties of each type are discussed, with an emphasis on the effect of yttria concentration on the properties of zirconia. The processing and sintering methods are also discussed as they have a direct impact on the properties of zirconia. The design of tooth preparation, specifically occlusal reduction, varies depending on the type of zirconia used in each case. Finally, a protocol for zirconia restoration bonding is described to ensure optimal bonding to the tooth structure.

CONCLUSION

Not all zirconia restorations are the same. The selection of zirconia type based on yttria concentration, processing and sintering methods, tooth preparation design, and adherence to the bonding protocol are all critical to the success and longevity of zirconia restorations.

CLINICAL SIGNIFICANCE

Zirconia restorations are the most commonly used indirect restorative material. The selection of the most appropriate zirconia type based on its yttria content, which determines its strength and translucency, is critical to the success and the longevity of the restoration. Tooth preparation design also influences the strength and translucency of the zirconia. Air-borne particle abrasion, followed by a ceramic primer and resin cement, can ensure a durable bond to the tooth structure.

Recent advances in glass-ceramics: Performance and toughening mechanisms in restorative dentistry

The use of glass-ceramics in the medical field has grown significantly since the 1980s. With excellent aesthetic properties, semi-translucency, outstanding mechanical properties, corrosion resistance, wear resistance and great biocompatibility and workability glass-ceramics is one of the most commonly used materials in restorative dentistry and is widely used in veneers, inlays, onlays, all-ceramic crowns, and implant abutments. This review provides an overview of the research progress of glass-ceramics in restorative dentistry, focusing on the classification, performance requirements, toughening mechanisms and their association with clinical performance, as well as the manufacturing and fabrication of glass-ceramics in restorative dentistry. Finally, the developments and prospects of glass-ceramics in restorative dentistry are summarized and discussed.

Etiology, Classification, and Restorative Management of Amelogenesis Imperfecta Among Children and Young Adults: A Scoping Review

Amelogenesis imperfecta (AI) is a rare genetic disorder affecting children and adults. Knowledge about AI is limited to clinical representation and radiographical findings. Various treatments are provided to children with AI, yet no definitive treatment guideline has been suggested in the literature. This scoping review highlights the knowledge of the etiology and classification of AI and synthesizes these findings in a comprehensive review, focusing mainly on the various forms of AI in children and management with a restorative conservative approach. Five electronic databases, namely, PubMed, Google Scholar, Embase, Web of Science, and Scopus, were searched for the relevant articles. The search was performed in two phases: first for title and abstract, and second for full-text articles. The studies included in this scoping review were published from 2013 to August 2023. The data extraction was done on a customized sheet. A total of 33 studies were included in this review, of which 19 were reports and series, seven were observational, and seven were reviews. Most patients included in this review suffered from the hypoplastic type of AI (54%), followed by hypomatured (36%), and hypocalcified (10%). The treatment modalities explained were divided into the following three phases: temporary, transient, and permanent. Almost all included reports suggested the requirement for guidelines for treating AI among young children. This scoping review suggests the need for guidelines for treating AI in children. Moreover, pediatric dentists should prioritize early diagnosis and treatment and long-term follow-up for AI in children to effectively enhance the patient's psychological well-being and overall quality of life.

Avulsion Injuries: Assessment and Management

Avulsion injuries, though relatively uncommon, are one of the most serious of dentoalveolar injuries. Replantation at the scene of the incident is almost always the treatment of choice whenever possible. This paper outlines a step-by-step approach for the management of avulsion injuries, including a splinting protocol. This aims to support general dental practitioners in feeling more confident with managing these injuries.

Understanding the Complexities of Cast Post Retention: A Comprehensive Review of Influential Factors

This comprehensive review delves into the intricate landscape of cast post retention in restorative dentistry, encompassing historical perspectives, contemporary techniques, and future directions. Examining factors ranging from tooth-related considerations to prosthesis-related dynamics, the review provides a detailed analysis of clinical techniques, including step-by-step procedures, common challenges, and innovative advancements. Technological breakthroughs, such as digital impressions, computer-aided design and computer-aided manufacturing (CAD/CAM) technology, three-dimensional (3D) printing, and finite element analysis, are explored for their transformative impact on precision and customization. The discussion extends to the promising future of cast post retention, emphasising emerging materials, the integration of artificial intelligence in treatment planning, and patient-specific approaches. Implications for clinical practice underscore the importance of individualised treatment planning and the adoption of advanced technologies. Recommendations for future research advocate for comprehensive long-term clinical studies, investigations into AI-driven treatment planning, and a focus on patient outcomes and satisfaction. This review consolidates existing knowledge and anticipates a future marked by enhanced precision, individualised care, and improved long-term success in cast post-retained restorations.

Metalloproteinases in Restorative Dentistry: An In Silico Study toward an Ideal Animal Model

In dentistry, various animal models are used to evaluate adhesive systems, dental caries and periodontal diseases. Metalloproteinases (MMPs) are enzymes that degrade collagen in the dentin matrix and are categorized in over 20 different classes. Collagenases and gelatinases are intrinsic constituents of the human dentin organic matrix fibrillar network and are the most abundant MMPs in this tissue. Understanding such enzymes' action on dentin is important in the development of approaches that could reduce dentin degradation and provide restorative procedures with extended longevity. This in silico study is based on dentistry's most used animal models and intends to search for the most suitable, evolutionarily close to Homo sapiens. We were able to retrieve 176,077 mammalian MMP sequences from the UniProt database. These sequences were manually curated through a three-step process. After such, the remaining 3178 sequences were aligned in a multifasta file and phylogenetically reconstructed using the maximum likelihood method. Our study inferred that the animal models most evolutionarily related to Homo sapiens were Orcytolagus cuniculus (MMP-1 and MMP-8), Canis lupus (MMP-13), Rattus norvegicus (MMP-2) and Orcytolagus cuniculus (MMP-9). Further research will be needed for the biological validation of our findings.

Alumina and glass-bead blasting effect on bond strength of zirconia using 10-methacryloyloxydecyl dihydrogen phosphate (MDP) containing self-adhesive resin cement and primers

In fact, bonding of zirconia restorations is still a big challenge in clinical situations and many bonding protocols discussed in literature might be still controversial. The aim of this was to study assess the bond strength of zirconia after alumina and glass-bead pre-treatments with two different primers in combination with conventional resin cement and 10-methacryloyloxydecyl dihydrogen phosphate (MDP) containing self-adhesive resin cement without priming. Fully sintered high translucent zirconia samples (n = 160) were assigned into 2 groups of pre-treatments (n  = 80): Alumina-sandblasting (AB) and Glass-bead (GB). Then, each group was divided into 4 sub-groups according to priming and cement used (n  = 20 each): conventional self-adhesive resin cement, MDP-silane Primer, MDP primer both with conventional self-adhesive resin cement, and MDP contained cement. Shear bond strength (SBS) was measured after thermocycling. Failure mode was analyzed using stereomicroscope. Contact angle and surface topography were investigated using other fully sintered samples (n  = 30) constructed for that sole purpose, divided into control (no pre-treatment [unmodified], alumina-, and glass-bead sandblasted groups). Two-way ANOVA was performed for SBS and failure mode was analyzed. The use of Alumina-sandblasting showed higher SBS compared to Glass-bead pre-treatment for MDP-silane primer (p = 0.034) and MDP primer (p < 0.001). While MDP contained cement showed higher but insignificant SBS when pre-treated with glass-beads. Alumina-sandblasting and glass-bead pre-treatments improve bond strength of zirconia combined using primers before cementation with conventional resin cement. Also, self-adhesive MDP contained cement along with surface pre-treatment showed the highest achievable bond strength. It was concluded that both alumina-sandblasting and glass-bead blasting improved SBS combined with MDP containing self-adhesive resin cement reducing the required clinical steps during cementation of zirconia restorations.

Evaluating the prospective crown-root ratio after extrusion and crown lengthening procedures in vitro

For restoration of extensively damaged teeth preprosthetic treatment measures are necessary. Crown lengthening and extrusion affect the prospective crown-root ratio (CRR). The subject of this in vitro study was to compute CRRs for both treatment approaches. 120 human maxillary central extracted incisors were measured. Measurements were calculated for five treatment groups: C (control), E-2 mm (extrusion of 2 mm), E-4 mm (extrusion of 4 mm), CL-2 mm (crown lengthening of 2 mm), and CL-4 mm (crown lengthening of 4 mm). Tooth (TL), root (RL), and crown lengths (CL) were measured from mesial (m) and facial (f) cemento-enamel junction (CEJ), and respective anatomic (CRR) and effective crown-root ratios (eCRR) were calculated. Following CRR values were computed for C: CRR-m = 0.4 ± 0.1, CRR-f = 0.7 ± 0.1. All crown-root ratios were lower (more favourable) for extrusion compared to crown lengthening (p < 0.001). ECRRs were higher than anatomic CRRs. CRR at mesial CEJ was significantly lower than CRR with facial CEJ as reference (p < 0.001). Mesial measurement-based calculations of CRR typically based on radiographic images should be interpreted with caution as they underestimate the eCRR. CRR can be expected as lower, i.e. more favourable, when teeth are extruded than crown lengthened.

Shear Strength of Repaired 3D-Printed and Milled Provisional Materials Using Different Resin Materials with and without Chemical and Mechanical Surface Treatment

The aim of this study was to assess the shear bond strength of 3D-printed and milled provisional restorations using various resin materials and surface finishes. There were 160 preliminary samples in all, and they were split into two groups: the milled group and the 3D-printed group. Based on the resin used for repair (composite or polymethylmethacrylate (PMMA)) and the type of surface treatment utilized (chemical or mechanical), each group was further divided into subgroups. The specimens were subjected to thermocycling from 5 °C to 55 °C for up to 5000 thermal cycles with a dwell time of 30 s. The mechanical qualities of the repaired material underwent testing for shear bond strength (SBS). To identify the significant differences between the groups and subgroups, a statistical analysis was carried out. Three-way ANOVA was used to analyze the effects of each independent component (the material and the bonding condition), as well as the interaction between the independent factors on shear bond strength. Tukey multiple post-hoc tests were used to compare the mean results for each material under various bonding circumstances. The shear bond strengths of the various groups and subgroups differed significantly (p < 0.05). When compared to the milled group, the 3D-printed group had a much greater mean shear bond strength. When compared to PMMA repair, the composite resin material showed a noticeably greater shear bond strength. In terms of surface treatments, the samples with mechanical and chemical surface treatments had stronger shear bonds than those that had not received any. The results of this study demonstrate the effect of the fabrication method, resin type, and surface treatment on the shear bond strength of restored provisional restorations. Particularly when made using composite material and given surface treatments, 3D-printed provisional restorations showed exceptional mechanical qualities. These results can help dentists choose the best fabrication methods, resin materials, and surface treatments through which to increase the durability and bond strength of temporary prosthesis.

A laboratory pilot study on voids in flowable bulk-fill composite restorations in bovine Class-II and endodontic access cavities after sonic vibration

This pilot study investigated whether sonic-powered application of a bulk-fill resin-based composite (RBC) in Class-II or endodontic access cavities reduces void formation. The crowns and roots of 60 bovine teeth with Class-II cavities (C) and endodontic access cavities (E) respectively, were assigned to ten groups (C1-C5, E1-E5). Cavities were filled with RBC (SDR flow + , one increment) using different application techniques: no adaptation (C1 + E1), spreading of RBC on the cavity surfaces with a dental explorer tip (C2 + E2), low (C3 + E3) or high frequency (C4 + E4) direct activation by inserting a sonic-powered tip into RBC and high frequency indirect activation with an ultrasonic insertion tip (C5 + E5). The restorations were light-cured and investigated for voids using microtomography. The number of voids and percentage of voids related to the volume were statistically analysed (α < 0.05). While most voids in Class-II restorations were observed in C4 (p ≤ 0.0031), no significant differences were found between the other groups (p > 0.05). The percentage of voids showed no differences in E1-E5 (p > 0.05). C4 showed a significantly higher percentage of voids compared to C2 (p < 0.001). There is no benefit in applying sonic vibration when filling Class-II or endodontic access cavities.

A critical review of dental biomaterials with an emphasis on biocompatibility

This paper presents the major achievements in the field of biomaterials in restorative dentistry and tissue regeneration reported over the past 3 years. The review aims to summarize the knowledge on important biomaterials and the emerging modification strategies to improve their biointegration, biological activity, mechanical properties, and resistance to the harsh oral environment. We also discuss the main opportunities and challenges associated with the use of biomaterials in dentistry.Much contemporary research focuses on the interactions between biomaterials and the surrounding tissues in the oral environment regarding adhesion, associated stresses and strains, and the durability of dental restoration materials. Dental biomaterials should support cell adhesion and activity, leading to dental tissue regeneration, and are also expected to effectively prevent bacterial infections and inhibit material corrosion in saliva. The degradation, dissolution or corrosion of restorative materials due to exposure to body fluids can alter the structure and mechanical properties of the material, causing various adverse effects.Another aspect addressed in recent literature is the improvement of the mechanical properties and esthetics of restorative materials. The surfaces of biomaterials are usually modified with polymers or nanomaterials to reduce friction while maintaining biocompatibility.Although all modern biomaterials are promising, there is an urgent need for more in vivo and clinical studies to investigate their biological advantages and disadvantages in detail. The computational techniques used to assess the properties of modern dental materials, particularly the mechanical ones, could assist in the development of the materials. Such an approach can help bring new biomaterials to the market by reducing complicated, tedious and expensive experimentation.

Forced surgical extrusion using an axial tooth extraction system as a practicable technique for preserving severely destroyed teeth? - Clinical outcomes up to 4.8 years

OBJECTIVE

Several extrusion techniques have been described to restore teeth with insufficient coronal tooth structure and to avoid their extraction. Still, there is little evidence for a treatment concept combining surgical extrusion using an atraumatic axial extraction system.

MATERIALS AND METHODS

A total of nine patients, each with an iso- or subgingival fractured tooth, were retrospectively examined. Treatment of the damaged tooth comprised an atraumatic forced surgical extrusion performed with an axial tooth extraction system and a more coronal positioning within the socket. The teeth were initially splinted and subsequently restored. The follow-up period was up to 57.1 months and averaged 36.5 (SD: ±13.5) months.

RESULTS

All nine teeth were still in situ, without signs of inflammation. During the period of the provisional restoration, six prosthetic complications occurred, which were resolved with little effort, whereas, success rate for the definitive restoration was 100%. No biological complications were observed concerning the root apex or soft tissue. The radiographically measured mean extrusion distance was 3.4 (SD: ±1.0) mm, so that a sufficient prosthetic ferrule could be reestablished.

CONCLUSIONS

Surgical extrusions using an axial tooth extraction system demonstrate low biological and prosthetic complications rates over observation time.

CLINICAL SIGNIFICANCE

The presented extrusion approach preserves soft and hard tissue and is an efficient treatment option for severely destroyed teeth. Saving hopeless teeth by this relatively predictable and feasible procedure has hardly any disadvantages for patients, and in case of failure, an implant or fixed partial denture are still an option.

Assessment of Proximal Protection Usage by Dental Students During Class II Cavity Preparations: An In Vivo Pilot Study

BACKGROUND

Class II cavity preparations in restorative dentistry pose a risk of iatrogenic damage to adjacent teeth as they could increase their susceptibility to caries and the need for additional restorative procedures. While previous research has explored this issue through in vitro and limited in vivo investigations, the direct clinical observation of proximal protection usage to prevent iatrogenic damage during class II cavity preparations is still limited.

AIM

This in vivo study aimed to assess the prevalence of proximal protection usage and extent of iatrogenic damage induced to adjacent surfaces upon occurrence during class II cavity preparations via direct visual inspection under magnification.

MATERIALS AND METHODS

Data were collected from restorative dentistry consultants supervising fourth-year undergraduate students. Information regarding cavity preparations, proximal protection usage, and iatrogenic damage was gathered through an electronic evaluation form via direct clinical observations once class II cavity preparations were finished. Statistical analyses, including ordinal logistic regression models, were employed to investigate associations and compute odds ratios (ORs).

RESULTS

We examined 82 teeth adjacent to class II cavity preparations in in vivo settings. The prevalence of proximal protection use was 72%, while the prevalence of iatrogenic damage was 17.1% overall, increasing to 47.8% when not using protection and 5.1% when using protective measures. Polishing and restoration of the induced damage were the primary management approaches. The use of protective measures, particularly matrix bands, significantly reduced the risk of iatrogenic damage (P < 0.05). Several factors, including arch, tooth surface, time, operator gender, and the state of the adjacent tooth before treatment, were examined but did not yield statistically significant associations.

CONCLUSION

Our study shows that most undergraduate dental students use proximal protection during class II cavity preparations, which are significant in reducing iatrogenic damage to the adjacent tooth. However, the literature shows that general practitioners often do not use proximal protection. The use of proximal protection should be reinforced and even required for the successful and safe treatment of proximal cavities. Future research with larger and more diverse samples is needed to understand the barriers to the use of proximal protection and develop interventions to promote its adoption.

A Look Into the Cytotoxicity of Composite Fillings: Friend or Foe?

Dental resin composites are widely used restorative materials in dentistry for the treatment of carious and non-carious lesions as well as pit and fissure sealants, cavity liners, and endodontic sealers. They consist of two parts: an organic resin matrix and an inorganic/organic filler. The organic resin matrix phase is made up of multifunctional monomers and light-sensitive initiators, while the inorganic/organic filler phase is made up of micro/nano-sized fillers that primarily serve as reinforcement. Despite being a very promising dental material, its monomeric component has some drawbacks. It is well known for leaching out during incomplete polymerization, which can result in cytotoxicity. Bis-GMA (bisphenol A-glycidyl methacrylate) is the most cytotoxic of all monomeric components that exhibit synthetic estrogenic effects. The purpose of this article is to assess the cytotoxic effects of dental composite, understand the possible mechanism behind them, and explore ways to screen for and reduce this harmful effect, as well as shed light on its future prospects.

Bonding stability of universal adhesives to feldspathic ceramic with or without prior silane application

PURPOSE

This study aimed to assess the bonding stability of three universal adhesives to a CAD-CAM feldspathic ceramic with or without prior silane application.

MATERIALS AND METHODS

The universal adhesives tested were Ambar Universal (FGM), Single Bond Universal (3M), and Ybond Universal (Yller). Scotchbond Multipurpose Plus (3M) was used as a control. The silane used was RelyX Ceramic Primer (3M). Microtensile bond strength (μTBS) to Vitablocs Mark II was measured after 24 h or 6 months of water aging (n = 20). Failure modes were observed through scanning electron microscopy, and pH and degree of C=C conversion (DC) of the adhesives were measured (n = 3). Data were analyzed using one-, two-, and three-way ANOVA.

RESULTS

The pH values differed significantly among the adhesives (p < 0.001), while the DC was similar (p = 0.141). The universal adhesives showed significant differences in μTBS, with higher immediate results when using silane and lower results after aging. Notably, a significant decrease in μTBS was observed after 6 months when silane was applied. In contrast, the control adhesive exhibited consistent results between the 24-h and 6-month storage periods. The universal adhesives showed a decrease in μTBS ranging from 25.5% to 40.1% after prolonged storage. Adhesive failures were predominant in all groups. The presence or absence of silane in the adhesive composition did not affect the bonding performance.

CONCLUSIONS

The application of a separate silane coupling agent improved the immediate bond strength of universal adhesives to CAD-CAM feldspathic ceramic. However, this bond strength significantly decreased after 6 months of water aging. The bond strength remained stable for universal adhesives when applied without silane after 6 months of aging.

Experts consensus on the procedure of dental operative microscope in endodontics and operative dentistry

The dental operative microscope has been widely employed in the field of dentistry, particularly in endodontics and operative dentistry, resulting in significant advancements in the effectiveness of root canal therapy, endodontic surgery, and dental restoration. However, the improper use of this microscope continues to be common in clinical settings, primarily due to operators' insufficient understanding and proficiency in both the features and established operating procedures of this equipment. In October 2019, Professor Jingping Liang, Vice Chairman of the Society of Cariology and Endodontology, Chinese Stomatological Association, organized a consensus meeting with Chinese experts in endodontics and operative dentistry. The objective of this meeting was to establish a standard operation procedure for the dental operative microscope. Subsequently, a consensus was reached and officially issued. Over the span of about four years, the content of this consensus has been further developed and improved through practical experience.

Knowledge and Attitude Toward Esthetic Dentistry and Smile Perception

INTRODUCTION

A smile is important in human communication and is increasingly valued in modern society. The perception of smile attractiveness is subjective and depends on many factors.

AIM

This study aimed to evaluate and compare knowledge and attitude related to esthetic dentistry in dental students versus dental interns, general dentists, and dental specialists, examine the self-perception of their smile, and identify parameters that influence smile perception.

METHODS

This cross-sectional study was conducted at King Abdulaziz University Dental Hospital in Jeddah, Saudi Arabia. Participants included dental students, interns, general practitioners, and specialists. They completed an electronic questionnaire covering demographics, knowledge about esthetic dentistry, attitudes toward smile perception, and previous dental treatments. Data analysis involved descriptive statistics, bivariate analysis, and chi-square tests.

RESULTS

A total of 275 individuals participated in our study. The study found that dental students' exposure and awareness of esthetic dentistry topics increased with academic progression. Gender, age, and marital status influenced self-perception and smile evaluation. More females perceived gender as an influencing factor in smile evaluation, while more males believed in the existence of an ideal smile. A substantial portion of the sample had undergone dental treatments, with no significant income-related disparities observed.

CONCLUSION

This study highlights differences in knowledge and attitudes among dental students and professionals. Dental education appears to impact students' exposure to esthetic dentistry concepts. Moreover, gender, age, and marital status influence self-perception and evaluation of others' smiles.

Applications, functions, and accuracy of artificial intelligence in restorative dentistry: A literature review

OBJECTIVE

The applications of artificial intelligence (AI) are increasing in restorative dentistry; however, the AI performance is unclear for dental professionals. The purpose of this narrative review was to evaluate the applications, functions, and accuracy of AI in diverse aspects of restorative dentistry including caries detection, tooth preparation margin detection, tooth restoration design, metal structure casting, dental restoration/implant detection, removable partial denture design, and tooth shade determination.

OVERVIEW

An electronic search was performed on Medline/PubMed, Embase, Web of Science, Cochrane, Scopus, and Google Scholar databases. English-language articles, published from January 1, 2000, to March 1, 2022, relevant to the aforementioned aspects were selected using the key terms of artificial intelligence, machine learning, deep learning, artificial neural networks, convolutional neural networks, clustering, soft computing, automated planning, computational learning, computer vision, and automated reasoning as inclusion criteria. A manual search was also performed. Therefore, 157 articles were included, reviewed, and discussed.

CONCLUSIONS

Based on the current literature, the AI models have shown promising performance in the mentioned aspects when being compared with traditional approaches in terms of accuracy; however, as these models are still in development, more studies are required to validate their accuracy and apply them to routine clinical practice.

CLINICAL SIGNIFICANCE

AI with its specific functions has shown successful applications with acceptable accuracy in diverse aspects of restorative dentistry. The understanding of these functions may lead to novel applications with optimal accuracy for AI in restorative dentistry.

Distinguishing skill levels with haptic simulation in restorative dentistry: Myth or reality?

INTRODUCTION

This study aims to validate that haptic simulator assistance could distinguish skill levels with haptic simulation in restorative dentistry.

MATERIALS AND METHODS

This work was carried out with 93 first-year, 87 third-year and 44 fifth-year dental students. The promotions of first- and fifth-year dental students made one session to represent the negative and the positive controls, respectively. The third-year dental students were the studied population. Whatever the group, the maximum time for each reparation was restricted to 3 min. All students have to perform the same three exercises. The third-year dental students performed four sessions spread over the whole university year. For each test, the total score provided by the simulator was recorded and analysed.

RESULTS

The exercises are not discriminating in direct vision while the exercise in indirect vision is very interesting to distinguish the levels of the learners.

CONCLUSION

The results underline that the exercises in indirect vision could distinguish different profiles of student having different preclinical and clinical levels, while making it possible to follow the acquisition of clinical competence.

Machine Learning Analysis of Microtensile Bond Strength of Dental Adhesives

Dental adhesives provide retention to composite fillings in dental restorations. Microtensile bond strength (µTBS) test is the most used laboratory test to evaluate bonding performance of dental adhesives. The traditional approach for developing dental adhesives involves repetitive laboratory measurements, which consumes enormous time and resources. Machine learning (ML) is a promising tool for accelerating this process. This study aimed to develop ML models to predict the µTBS of dental adhesives using their chemical features and to identify important contributing factors for µTBS. Specifically, the chemical composition and µTBS information of 81 dental adhesives were collected from the manufacturers and the literature. The average µTBS value of each adhesive was labeled as either 0 (if <36 MPa) or 1 (if ≥36 MPa) to denote the low and high µTBS classes. The initial 9-feature data set comprised pH, HEMA, BisGMA, UDMA, MDP, PENTA, filler, fluoride, and organic solvent (OS) as input features. Nine ML algorithms, including logistic regression, k-nearest neighbor, support vector machine, decision trees and tree-based ensembles, and multilayer perceptron, were implemented for model development. Feature importance analysis identified MDP, pH, OS, and HEMA as the top 4 contributing features, which were used to construct a 4-feature data set. Grid search with stratified 10-fold cross-validation (CV) was employed for hyperparameter tunning and model performance evaluation using 2 metrics, the area under the receiver operating characteristic curve (AUC) and accuracy. The 4-feature data set generated slightly better performance than the 9-feature data set, with the highest AUC score of 0.90 and accuracy of 0.81 based on stratified CV. In conclusion, ML is an effective tool for predicting dental adhesives with low and high µTBS values and for identifying important chemical features contributing to the µTBS. The ML-based data-driven approach has great potential to accelerate the discovery of new dental adhesives and other dental materials.

Trueness, Flexural Strength, and Surface Properties of Various Three-Dimensional (3D) Printed Interim Restorative Materials after Accelerated Aging

Various 3D printing systems for interim fixed dental restorations are commercially available. This study aimed to evaluate the physical and mechanical properties of 3D printed resins used for interim restorations fabricated using various 3D printing systems and printing angulations after accelerated aging. Three different interim restorative materials were provided and printed using their specific 3D printing systems (A: NextDent; B: Asiga; C: Nova3D), and the testing specimens from each system were printed at two building angles: (1) 0° and (2) 90°. The six groups were A1, A2, B1, B2, C1, and C2, with sixteen specimens per group. Half of the specimens in each group (N = 8) were subjected to accelerated aging, including simulated brushing and thermocycling. Three-point bending, surface roughness, and Vickers microhardness tests were performed. Two-way ANOVA and Fisher's multiple tests were used for statistical analyses. The most accurate systems were found in groups C1 and C2 for length, A1 and B1 for width, and A1 and C1 for height. The specimen trueness only changed after aging for groups B1, B2, and C1. The flexural strength of the A2 group (151 ± 7 MPa) before aging was higher than that of the other groups, and the strength decreased after aging only for groups A1 and A2. The flexural strength, microhardness, and surface roughness of the 3D printed interim resins after aging varied depending on the material, system used, and printing angle.

Benefits of using magnification in dental specialties - a narrative review

An increased number of clinicians are using magnification to facilitate their vision when carrying out dental examinations and treatments. The best instrument for this purpose is the microscope, which has proven to enhance quality, longevity and outcome of clinical work. Its use in some dental specialties (such as endodontics) is now well established, but there is also a role for this equipment in other branches of dentistry. To anticipate the contribution of magnification to dentistry in general, recent research and experimental data on the importance of magnification devices will be considered, from the perspectives of optical issues, diagnosing methods and treatment options. It will be shown that, while the microscope is vital to certain specialties (such as endodontics, periodontics, restorative dentistry and prosthodontics), it has little effect on others (orthodontics, for example). This synthesis of current researchattempts to shed light on the optimal magnification used in certain clinical situations, the distinctive benefits of loupes and microscopes for each dental branch, as well as their drawbacks.

Decision Making in the Restoration of Endodontically Treated Teeth: Effect of Biomimetic Dentistry Training

The restoration of endodontically treated teeth (ETT) is challenging as these teeth often present with structural deficiencies. Currently, there is no consensus regarding the final restoration choice. Historically, the full coverage crown was the universally selected treatment for endodontically treated teeth. With advances in adhesive and biomimetic dentistry, more minimally invasive treatment modalities have become a viable option. With this study, we aim to understand the restorative decision of the general dentist with or without additional training in biomimetic dentistry. Seventy-eight general dentists, with or without biomimetic training, were surveyed to determine their restorative preferences on five extracted posterior teeth, categorized according to volumetric loss of tooth structure, as indicated by the number of missing walls, the isthmus width, the presence or absence of marginal ridges, and cusps. CAD/CAM reconstructions were made with the teeth to analyze the volume of tooth loss and compare these with the survey results. Data were compared using the chi-squared test and Fisher's exact test. The frequency of responses recommending a crown and the volume of tooth loss were correlated using the Pearson test (p < 0.05). For all five teeth, survey responses showed a statistically significant difference in the restorative decision of full coverage versus alternative restorations, with biomimetic dentists selecting a direct restoration or inlay/onlay in lieu of a full coverage crown (n = 63, p < 0.05). The age of the participant did not have a significant impact on the restorative decision making process for these teeth. The biomimetic trained dentists showed a greater tendency to select a crown option only when the volume of tooth loss was greatest, otherwise their restorative decisions tended towards the conservative treatment options. This study also demonstrates a novel method of digitally developing a volume of tooth loss to compare against the visual interpretation of the volume of tooth loss.

Intramedullary bone tissue reaction of ion-releasing resin-modified glass-ionomer restoration versus two calcium silicate-based cements: an animal study

This comparative study was conducted to assess the intramedullary bone tissue reaction of an ion-releasing resin modified glass-ionomer cement with claimed bioactivity (ACTIVA bioactive resin) restorative material versus Mineral Trioxide Aggregate High Plasticity (MTA HP) and bioceramic putty iRoot BP Plus. Fifty-six adult male Wistar rats were assigned into 4 equal groups (14 rats each). A surgical intramedullary bi-lateral tibial bone defects were performed in rats of the control group I (GI) and left without any treatment to be considered as controls (n = 28). The rats of groups II, III and IV were handled as group I except that the tibial bone defects were filled with ACTIVA, MTA HP and iRoot BP, respectively. In all groups, rats were euthanized after one month and specimens were processed to histological investigation, SEM examination and EDX elemental analysis. In addition, semi-quantitative histomorphometric scoring system was conducted for the following parameters; new bone formation, inflammatory response, angiogenesis, granulation tissue, osteoblasts and osteoclasts. The clinical follow-up outcome of this study revealed the recovery of rats after 4 days post-surgical procedure. It was observed that the animal subjects returned to their routine activities, e.g., walking, grooming and eating. The rats showed normal chewing efficiency without any weight loss or postoperative complications. Histologically, the control group sections showed scanty, very thin, new bone trabeculae of immature woven type located mostly at the peripheral part of the tibial bone defects. These defects exhibited greater amount of thick bands of typically organized granulation tissue with central and peripheral orientation. Meanwhile, bone defects of ACTIVA group showed an empty space surrounded by thick, newly formed, immature woven bone trabeculae. Moreover, bone defects of MTA HP group were partially filled with thick newly formed woven bone trabeculae with wide marrow spaces presented centrally and at the periphery with little amount of mature granulation tissue at the central part. The iRoot BP Plus group section exhibited an observable woven bone formation of normal trabecular structures with narrow marrow spaces presented centrally and at the periphery showed lesser amount of well-organized/mature granulation tissue formation. Kruskal Wallis test revealed total significant differences between the control, ACTIVA, MTAHP and iRoot BP Plus groups (p < 0.05). Meanwhile, Mann-Whitney U test showed significant difference between control and ACTIVA groups, Control and MTA HP groups, control and iRoot BP Plus groups. ACTIVA and MTA HP groups, ACTIVA and iRoot BP Plus (p ˂ 0.05) with no significant difference between MTA HP and iRoot BP Plus (p > 0.05). The elemental analysis outcome showed that the lesions of the control group specimens were filled with recently created trabecular bone with limited marrow spaces. EDX tests (Ca and P analysis) indicated a lower degree of mineralization. Lower amounts of Ca and P was expressed in the mapping analysis compared with other test groups. Calcium silicate-based cements induce more bone formation when compared to an ion-releasing resin modified glass-ionomer restoration with claimed bioactivity. Moreover, the bio-inductive properties of the three tested materials are likely the same. Clinical significance: bioactive resin composite can be used as a retrograde filling.

Bismuth release from endodontic materials: in vivo analysis using Wistar rats

Calcium silicate-based materials are used to block the communication between the root canal and the periodontal ligament space. This brings the materials into contact with tissues and the potential for local and systemic elemental release and movement. The aim of the study was to evaluate the elemental release of bismuth from ProRoot MTA in contact with connective tissues after 30 and 180 days as well as any accumulation in peripheral organs using an animal model. Tricalcium silicate and hydroxyapatite containing 20% bismuth oxide (HAp-Bi) were used as controls. The null hypothesis was that bismuth migrates from tricalcium silicate-based materials when associated with silicon. The materials were examined using scanning electron microscopy, energy dispersive spectroscopy (SEM/EDS) and X-ray diffraction prior to implantation as well as using SEM/EDS, micro X-ray fluorescence and Raman spectroscopy after implantation to assess elemental presence in surrounding tissues. Histological analysis was used to evaluate the changes in tissue architecture and inductively coupled plasma mass spectrometry (ICP-MS) was used to investigate the elemental deposition. For the systemic investigation, routine blood analysis was performed and organs were obtained to evaluate the presence of bismuth and silicon using ICP-MS after acid digestion. In the histological analysis of the implantation sites, macrophages and multinucleated giant cells could be observed after 30 days which after 180 days became a chronic infiltrate; although, no major differences were identified in red and white blood cell analyses and biochemical tests. Implantation altered the materials as observed in the Raman analysis and bismuth was detected both locally and within kidney samples after both periods of analysis, indicating the potential for accumulation of bismuth in this organ. Smaller amounts of bismuth than observed in the kidney were also detected in blood, liver and brain for the ProRoot MTA and HAp-Bi after 180 days. Bismuth was released from the ProRoot MTA locally and was detected systemically and in samples without silicon; thus, the null hypothesis was rejected. The bismuth release demonstrated that this element accumulated both locally and systemically, mainly in the kidneys in comparison with brain and liver regardless of the material base.

Dental Fiber-Post Systems: An In-Depth Review of Their Evolution, Current Practice and Future Directions

The field of dental medicine is constantly evolving and advancing toward minimally invasive techniques. Several studies have demonstrated that bonding to the tooth structure, particularly enamel, yields the most predictable results. In some instances, however, significant tooth loss, pulpal necrosis, or irreversible pulpitis may limit the options available to the restorative dentist. In these cases, placement of a post and core followed by a crown is the preferred treatment option, provided all requirements are met. This literature review provides an overview of the historical development of dental FRC post systems as well as a comprehensive examination of the currently available posts and their bonding requirements. In addition, it offers valuable insights for dental professionals seeking to understand the current state of the field and the prospects of dental FRC post systems.

Conservative esthetic management of brown enamel fluorosis using combination therapy: A clinical report

Dental fluorosis is caused by ingestion of excessive fluoride during tooth development resulting in hypomineralization of the enamel and can present as white or brown intrinsic lesions. This case report describes a combination of minimally invasive techniques: microabrasion, bleaching, and resin infiltration to address brown enamel fluorosis present on the maxillary anterior teeth of a young patient. Before resin infiltration, air microabrasion was targeted at subsurface lesions located on the maxillary central and lateral incisors, and chairside bleaching was done with 37% hydrogen peroxide (Opalescence). After which, hypoplastic lesions on the buccal surfaces were etched before being treated with two sessions of resin infiltration (ICON and DMG). Following treatment, satisfactory esthetic outcomes were achieved. Accurate diagnosis, depth of lesions, and understanding the effectiveness and limitations of each technique are essential to select the appropriate type of treatment to obtain the best esthetic outcome. In conclusion, the conservative management of varying severity of dental fluorosis may require the appropriate use of combination treatment modalities, such as microabrasion, bleaching and resin infiltration, when clinically indicated, to address the treatment needs and achieve a desired outcome.

Soft Tissue Grafting Procedures before Restorations in the Esthetic Zone: A Minimally Invasive Interdisciplinary Case Report

An esthetically pleasing smile is a valuable aspect of physical appearance and plays a significant role in social interaction. Achieving the perfect balance between extraoral and intraoral tissues is essential for a harmonious and attractive smile. However, certain intraoral deficiencies, such as non-carious cervical lesions and gingival recession, can severely compromise the overall aesthetics, particularly in the anterior zone. Addressing such conditions requires careful planning and meticulous execution of both surgical and restorative procedures. This interdisciplinary clinical report presents a complex case of a patient with esthetic complaints related to asymmetric anterior gingival architecture and severely discolored and eroded maxillary anterior teeth. The patient was treated using a combination of minimally invasive ceramic veneers and plastic mucogingival surgery, resulting in a successful outcome. The report emphasizes the potential of this approach in achieving optimal esthetic results in challenging cases, highlighting the importance of an interdisciplinary team approach in achieving a harmonious balance between dental and soft tissue aesthetics.

A novel glass ionomer cement with silver zeolite for restorative dentistry

OBJECTIVE

To develop an antimicrobial silver zeolite glass ionomer cement (SZ-GIC) and determine its biocompatibility, physical, adhesive and antibacterial properties.

METHODS

Silver nitrate and sodium zeolite were used to synthesize silver zeolite (SZ). SZ-GICs were prepared by incorporating SZ into GIC at 5% (SZ-GIC5), 2% (SZ-GIC2), or 1% (SZ-GIC1) by weight, respectively. The SZ-GICs were characterized by evaluating surface morphology, topography and elemental composition. SZ-GICs' biocompatibility was assessed by evaluating cell cytotoxicity. Their physical properties were determined by testing setting time, compressive strength, flexural strength, water sorption and solubility. Their adhesive property was assessed by evaluating micro-tensile bond strength. Their antibacterial properties were assessed by evaluating biofilm growth kinetic, metabolic activity, viability and morphology. GIC was used as a control.

RESULTS

SZ was a three-dimensional crystalline mineral. SZ-GICs (including SZ-GIC 5, 2 and 1) showed similar surface morphology and topography to GIC. SZ-GIC1 and GIC had no difference in cell cytotoxicity (p>0.05). SZ-GICs and GIC showed no difference in setting time (p>0.05). SZ-GICs had higher compressive and flexural strength than GIC (p<0.05). SZ-GIC2 and SZ-GIC1 showed lower water sorption and solubility than GIC (p<0.05). SZ-GICs had higher micro-tensile bond strength than GIC (p<0.05). Biofilms on SZ-GICs' surfaces showed lower colony-forming units, decreased metabolic activities, higher percentages of dead cells and more ruptured bacterial cells compared with those on GIC.

CONCLUSION

SZ-GIC with silver zeolite at 1% by weight are as biocompatible as conventional GIC. The SZ-GICs have enhanced physical, adhesive and antibacterial properties than GIC.

CLINICAL SIGNIFICANCE

A silver zeolite glass ionomer cement was developed. The SZ-GICs have great potential for caries prevention and management.

Randomised controlled trial on testing an increased vertical dimension of occlusion prior to restorative treatment of tooth wear

BACKGROUND

Evaluation of a new vertical dimension of occlusion (VDO) in complex restorative treatments is considered a necessary step prior to placement of restorations.

OBJECTIVES

This randomised controlled trial (RCT) aimed to assess the effects of using an evaluation of a VDO increase before restorative treatment in patients with moderate-to-severe tooth wear, on OHRQoL, freeway space (FWS) and interventions to restorations.

METHODS

Forty-two patients with tooth wear were included and randomly allocated to either a test phase with a Removable Appliance (RA) or no test phase. Restorative treatment consisted of restoration of all teeth using composite restorations in an increased VDO. OHIP-score, freeway space (FWS) and clinical acceptability of restorations were assessed at baseline and at recall appointments (1 month and 1 year). Intervention to restoration was scored in case of material chipping or when the abutment tooth had increased sensitivity that could be linked to occlusal overloading. ANCOVA analyses, Univariate Cox regression, t-tests and descriptive analyses were performed (p < .05).

RESULTS

Clinical follow-up after 1 year was completed for 41 patients. No significant effect of testing the VDO with a RA could be found on the OHIP-score (p = .14). Reduction of FWS in the RA group, compared to the control group, was significantly lower at 1 year (p = .01, 95% CI -1.09 to -0.15). No effect on early interventions to restorations was found (p = .94).

CONCLUSION

This RCT showed that a removable appliance is not indicated to functionally test the increased VDO prior to restorative treatment in patients with tooth wear.

Investigating correlations between the PAT and three hand-skill exercises to performance in preclinical laboratory courses

OBJECTIVES

Perceptual ability test (PAT) is a valid determinant for spatial perceptions. However, proven psychomotor skill tests for dentistry do not currently exist. This study aimed to determine whether performance on the PAT, Operation game, mirror tracing, and wax carving exercises correlate to preclinical laboratory performance in Dental Anatomy and Restorative Dentistry courses.

METHODS

First-year dental students (n = 96) participated in the study. Final laboratory grades were obtained from course directors of preclinical Restorative Dentistry and Dental Anatomy courses. Admissions committee provided participants' PAT results. Participants completed a wax carving exercise by carving a cube and a semicircle into a wax block using the wax subtraction method. Two calibrated faculty graded the carvings as Ideal (5), Satisfactory (3), or Unsatisfactory (1). Time to complete the Operation game and number of infractions were recorded. Participants traced the six-pointed star pattern on the Auto Scoring Mirror Tracer instrument in both clockwise and counterclockwise directions. Completion times and number of instances outside the pattern were recorded. Spearman Rank Correlations were used to determine associations at 0.05 confidence interval.

RESULTS

Mean PAT score was 21.7; mean times to complete the Operation game and mirror tracing exercise were 4:20 and 1:30, respectively. Mean score on the wax carving exercise was 3.19. Correlations between the independent and dependent variables were minimal to weak. The wax carving exercise was the most reliable predictor of performance.

CONCLUSIONS

When PAT scores are striated into low (less than 20), middle (21-22), and high (23-30), it was possible to predict performance in both preclinical laboratory courses.

Five-Year Clinical Performance of Complex Class II Resin Composite and Amalgam Restorations-A Retrospective Study

The aim of this retrospective study was to investigate the clinical performance of posterior complex resin composite (RC) and amalgam (AM) restorations after a five-year period. One hundred and nineteen complex Class II restorations placed by dental students were evaluated using the USPHS criteria. Data were analyzed using Chi-square, Mann-Whitney, and Wilcoxon tests at a 0.05 level of significance. After five years, the percentages of clinically satisfactory complex Class II RC and AM restorations were 78% and 76.8%, respectively. The main reasons for the failure of AM restorations included secondary caries (Bravo-10.1%), defective marginal adaptation (Charlie-8.7%), and fracture of the tooth (Bravo-7.2%). RC restorations presented failures related to the fracture of the restoration (Bravo-16%) and defective marginal adaptation (Charlie-8.2%). There was a significantly higher incidence of secondary caries for AM restorations (AM-10.1%; RC-0%; p = 0.0415) and a higher number of fractures for RC restorations (AM-4.3%; RC-16%; p = 0.05). Regarding anatomy, AM restorations presented a significantly higher number of Alfa scores (49.3%) compared to RC restorations (22.4%) (p = 0.0005). The results of the current study indicate that complex class II RC and AM restorations show a similar five year clinical performance.

Minimally Invasive Laminate Veneer Therapy for Maxillary Central Incisors

Minimally invasive dentistry is a considered process that requires the clinician to be prepared with the ideal sequence and the tools needed. This report describes a well-planned ultraconservative approach using only two ceramic laminate veneers for the maxillary central incisors to significantly improve the patient's overall smile. A 30-year-old female presented with the chief complaints of having diastemas between the central and lateral incisors as well as incisal wear. Diagnostic wax-up and mock-up were performed, and the patient approved the minimally invasive treatment with veneers only for central incisors. A reduction guide aided the conservative tooth preparations, and hand-crafted feldspathic veneers were bonded under total isolation with a rubber dam. The two final conservative veneers significantly improved the smile and fulfilled the patient's expectations. Following proper planning and sequencing, predictable outcomes were obtained and fulfilled the patient's esthetic demands. Minimally invasive restorative dentistry with only two single veneers can impact the entire smile frame. Overtreatment in the esthetic zone is unnecessary to meet a patient's esthetic expectations.

Stamp Technique: An Explorative SEM Analysis

BACKGROUND

Achieving correct tooth anatomy and saving time at the dental chair are some of the goals of modern restorative dentistry. Stamp technique has gained acceptance in clinical practice. The aim of this study was to evaluate the effectiveness of this technique in terms of microleakage, voids, overhangs and marginal adaptation of Class I restorations, and to analyse the operative times in comparison with traditional restorative procedures.

METHODS

Twenty extracted teeth were divided into 2 groups. Ten teeth in the study group (SG) were Class I prepared and restored using stamp technique, and ten teeth in the control group (CG) were Class I restored traditionally. SEM analysis was performed to evaluate voids, microleakage, overhangs, and marginal adaptation, and operative times were recorded. A statistical analysis was performed.

RESULTS

There were no significant differences in microleakage, marginal adaptation and filling defects between the two groups, however, the stamp technique seems to facilitate the formation of large overflowing margins that require a careful finishing phase.

CONCLUSIONS

Stamp technique does not seem to have any critical aspects in terms of restoration durability and it can be performed in a short time.