Repair of fractured metal-ceramic restoration using CAD/CAM technologies. Case report.

Fractures in esthetic ceramic veneering are one of the potential failure modes during prosthetic treatment. Depending on the type of chipping fracture, there are three possible outcomes: replacement, restoration repair, or polishing of the fractured area. Computer-aided design and manufacturing (CAD/CAM) technologies provide new methods to the maintenance and repair of fixed metal-ceramic restorations. Here, we report the case of a 68-year-old patient who came to the dentist with comcerns about his appearance due to spontaneous gingival bleeding and a fracture in the ceramic veneering of a metal-ceramic restoration. The patient reported occurrences of bruxism. The proposed treatment plan included consultation with a cardiologist, periodontal treatment, polishing of the chipped areas, repair of the fractured zone with an exposed metal core, and fabrication of a mouth guard. Once the ceramic veneering on the palatal and buccal sides of the retainers had been completely removed, a digital impression was obtained and sent to the dental lab so that milled zirconium veneer could be manufactured. The veneering was cemented the next day using the standard prosthetic field preparation process and resin-modified glass ionomer cement. In conclusion, fixed metal-ceramic restorations that have fractured can be successfully repaired using CAD/CAM methods and materials.

Bonding Efficiency between Artificial Teeth and Denture Base in CAD/CAM and Conventional Complete Removable Dentures.

A common challenge encountered with both traditional and digitally produced dentures involves the extraction of artificial teeth from the denture base. This narrative review seeks to present an updated perspective on the adherence of synthetic teeth for denture base materials, employing diverse methods. Dental technicians often employ chemical approaches and mechanical techniques (including abrasion, laser treatment, and abrasive blasting) to augment the retention of denture teeth. However, the efficacy of these treatments remains uncertain. In certain instances, specific combinations of Denture Base Resin (DBR) materials and artificial teeth exhibit improved performance in conventional heat-cured dentures following these treatments. The primary reasons for failure are attributed to material incompatibility and inadequate copolymerization. As new denture fabrication techniques and materials continue to emerge, further research is imperative to identify optimal tooth-DBR combinations. Notably, 3D-printed tooth-DBR combinations have demonstrated reduced bond strength and less favorable failure patterns, while utilizing milled and traditional combinations appears to be a more prudent choice until advancements in additive manufacturing enhance the reliability of 3D-printing methods.

Assessment of CAD/CAM Fabrication Technologies for Post and Core Restorations-A Narrative Review.

The primary objective of this study is to conduct a comprehensive review of the existing literature that discusses research on post and core restorations, covering aspects such as their composition, manufacturing methods, and clinical effectiveness. The methodology employed in this review encompasses the implementation of a well-defined search strategy, the establishment of criteria for inclusion and exclusion, and the selection of relevant studies to summarize their findings. To gather relevant literature published between 1993 and 2023, the research team conducted separate searches on PubMed, Web of Science, and Embase databases. In total, 168 titles were initially retrieved from these electronic databases. By applying the predefined exclusion criteria, the researchers identified 73 articles that specifically address the conventional and computer-aided design/computer-aided manufacturing (CAD/CAM) technologies employed in post and core restorations. These treatments are commonly employed to restore teeth that have received endodontic therapy and subsequently experienced loss of dental structure. The development of computerized technology for the creation of customized posts and cores has emerged as a straightforward and efficient alternative to traditional methods. The review synthesizes papers discussing the techniques and materials involved in CAD/CAM-based construction of post and cores. It explores strategies for restoring endodontically treated teeth, highlighting both direct and indirect approaches. Commonly mentioned materials include zirconia, composite resin, and hybrid ceramics. Despite the limited literature on CAD/CAM post and core procedures, the review emphasizes the necessity of further research to assess long-term outcomes and efficacy. Additionally, it suggests including implications for future research and clinical recommendations to enhance the depth and practical relevance of the review.

Comparative Analysis of the Mechanical Properties and Biocompatibility between CAD/CAM and Conventional Polymers Applied in Prosthetic Dentistry.

Modern media often portray CAD/CAM technology as widely utilized in the fabrication of dental prosthetics. This study presents a comparative analysis of the mechanical properties and biocompatibility of CAD/CAM (Computer-Aided Design/Computer-Aided Manufacturing) polymers and conventional polymers commonly utilized in prosthetic dentistry. With the increasing adoption of CAD/CAM technology in dental laboratories and practices, understanding the differences in material properties is crucial for informed decision-making in prosthodontic treatment planning. Through a narrative review of the literature and empirical data, this study evaluates the mechanical strength, durability, esthetics, and biocompatibility of CAD/CAM polymers in comparison to traditional polymers. Furthermore, it examines the implications of these findings on the clinical outcomes and long-term success of prosthetic restorations. The results provide valuable insights into the advantages and limitations of CAD/CAM polymers, informing clinicians and researchers about their suitability for various dental prosthetic applications. This study underscores the considerable advantages of CAD/CAM polymers over conventional ones in terms of mechanical properties, biocompatibility, and esthetics for prosthetic dentistry. CAD/CAM technology offers improved mechanical strength and durability, potentially enhancing the long-term performance of dental prosthetics, while the biocompatibility of these polymers makes them suitable for a broad patient demographic, reducing the risk of adverse reactions. The practical implications of these findings for dental technicians and dentists are significant, as understanding these material differences enables tailored treatment planning to meet individual patient needs and preferences. Integration of CAD/CAM technology into dental practices can lead to more predictable outcomes and heightened patient satisfaction with prosthetic restorations.

A 3D-simulation study of the deformation, tension, and stress of 3D-printed and conventional denture base materials after immersion in artificial saliva.

INTRODUCTION: The worldwide application of digital technology has presented dentistry with transformative opportunities. The concept of digital dentures, incorporating computer-aided design (CAD) and computer-aided manufacturing (CAM) techniques, holds the promise of improved precision, customization, and overall patient satisfaction. However, the shift from traditional dentures to their digital counterparts should not be taken lightly, as the intricate interplay between oral physiology, patient comfort, and long-term durability requires thorough examination.

Clinical and laboratory study of corrosion resistance of a base dental alloy for selective laser melting.

INTRODUCTION: CAD/CAM technologies are becoming widely used for the production of metal ceramic dental restorations. Powder Co-based alloys are developed for selective laser melting. The corrosion resistance of the dental alloy affects the biocompatibility, functional suitability, and longevity of the prosthetic restoration.

A Comparative Analysis of Post-Retraction Changes in Gingival Height after Conventional and Surgical Gingival Displacement: Rotary Curettage, Diode and Er:YAG Laser Troughing.

The aim of the current article is to analyze and compare post-retraction gingival height changes resulting from six different types of gingival-displacement methods, encompassing both conventional and surgical approaches. The study involved a comparative analysis of 263 teeth (consisting of 128 front teeth, 69 premolars, and 66 molars) from 23 patients. For the investigation, three classic retraction methods were utilized, namely the single-cord technique, retraction paste Expasyl, and retraction paste Astringent. Additionally, three surgical techniques were employed, which included ceramic bur rotary curettage, Er:YAG laser troughing, and diode laser troughing. A randomized split-mouth design was implemented, and a significance level of 0.05 was used for the study. The recovery of the free gingival margin height was assessed on gypsum models that were scanned using an intraoral scanner during the first and second week after the retraction procedure. The results revealed that all retraction methods, except for ceramic bur rotary curettage, led to clinically insignificant levels of gingival recession. The article provides insights into the effectiveness and safety of various gingival-displacement techniques, highlighting that most methods tested in the study resulted in minimal or negligible gingival recession post-retraction.

Clinical Evaluation of Corrosion Resistance, Ion Release, and Biocompatibility of CoCr Alloy for Metal-Ceramic Restorations Produced by CAD/CAM Technologies.

BACKGROUND: CAD/CAM technologies facilitate using powder CoCr alloys to produce metal-ceramic dental restorations. However, base alloys may induce oxidative stress in the oral cavity due to corrosion and ion release. This study evaluated resistance to corrosion and release of metal ions from 3D printed CoCr dental alloy and their effect on oral oxidative stress. METHODS: Metal-ceramic crowns with 3D printed copings from CoCr alloy EOS CobaltChrome SP2 (EOS, Germany) were fabricated for 35 patients. Inductively coupled plasma mass spectrometry (ICP-MS) was used for measuring the concentration of Co and Cr ions in non-stimulated saliva before prosthetic treatment (BPT), at 2 h and 7 days after the dental treatment (APT2, APT7, respectively). Open circuit potentials (Eocp) were evaluated at APT2 and APT7. Estimating oral oxidative stress, measurements of 8-isoprostaglandin F2-alpha were conducted using liquid chromatography-tandem mass spectrometry (LC-MS/MS) at stages BPT, APT2, and APT7. RESULTS: Salivary Co level increased at APT2 and decreased to the initial levels at APT7. No statistical difference was found between the levels of 8-isoPGF2-alpha measured, and between the Eocp measurements at APT2 and APT7. CONCLUSIONS: The studied alloy showed stable corrosion resistance and the metal ion release did not induce oral oxidative stress.

Surgical Treatment of Lung Abscess Due to an Awn Aspiration in a 9-Year-Old Child: A Case Report.

INTRODUCTION: Foreign body aspiration is a common condition in the child population and is one of the leading causes of accidental deaths in children. The aspiration of an awn (grass inflorescences) is extremely rare. AIM OF THE STUDY: This study aims to describe the symptoms, diagnosis, therapeutic difficulties, and results of the aspiration of grass inflorescence. They are all related to the shape of the awn's head and its behavior in the tracheobronchial tree. CASE DESCRIPTION: We present a 9-year-old boy with a history of an awn aspiration and recurrent respiratory infections. After antibiotic and symptomatic treatment, two bronchoscopies were performed, and both showed stenosis and obturation of the segmental and subsegmental bronchi of the left posterior basal segment, but no foreign body was found. After recanalization and continuous medicamentous treatment, a computed tomography (CT) verified the lung abscess. Video-assisted thoracoscopic surgery (VATS) was performed, and an atypical lung resection was conducted. During the surgery, a foreign body-grass inflorescence from the species Hordeum murinum-was found in the resected tissue. The patient recovered uneventfully after the surgery. CONCLUSIONS: Grass inflorescence aspiration in the child population is an extremely rare event, and it represents a diagnostic and therapeutic issue. The exact timing of surgery is very important to reduce complications and avoid death.

Fracture resistance of 3-unit monolithic ZrO2 ceramics FPDs with different preparation designs of the distal abutment - an in-vitro study.

INTRODUCTION: Masticatory pressure increases in the distal areas of the dentition. This should be considered when restoring partially edentulous patients with a metal-free fixed partial denture (FPD). An alternative abutment preparation design can be used in order to increase the materials' volume in the most fracture-prone "connector area" of an FPD. The increased size of the connection might positively influence the constructions' mechanical durability, thereby increasing its success and survivability. AIM: The aim of the present study was to investigate the influence of two preparation designs of the distal abutment on the fracture resistance of three-unit, monolithic, ZrO2 FPDs. MATERIALS AND METHODS: 3D printed replicas of a partially edentulous mandibular segment and a ZrO2, milled in full-contour, three-unit FPDs were used for this investigation. Two experimental groups (n=10 ) were defined based on the preparation design of the distal abutment tooth - classical shoulder preparation 0.8 mm deep, and endocrown preparation with a 2-mm retention cavity. The bridge - mandibular segment replica assembly was done with relyXU200(3M ESPE, USA), light-cured for 10 seconds per side with D-light Duo (GC, Europe). After cementation the test specimens were subjected to loading in a universal testing machine Zwick (Zwick-Roell Group, Germany). Statistical analysis was performed using R and includes descriptive statistics, t-test for quantitative and chi-squared test for qualitative variables. RESULTS: The results showed no difference between the two studied groups in the maximum force required to fracture the test specimens [t=-1.8088 (17.39), p-value=0.087; P>0.05]. 95% of the fracture lines were located in the distal connector. CONCLUSIONS: Within the limitations of this study, it can be concluded that both tested preparation designs show similar results in terms of the load required to fracture the test specimens. Furthermore, it is confirmed that the distal connector is the weakest area of an all-ceramic 3-unit FPD in the posterior area.

The impact of dental metal restorations on the oral oxidative stress level.

Background: Dental materials may influence the equilibrium between production and destruction of free radicals, thus creating conditions for developing of local or general oxidative stress. Metal ions, emitted from base dental alloys, may cause changes in cell structures and functions. Isoprostane concentration may indicate possible cell damage, caused by free radicals, and can be used for evaluation of the oxidative stress level. The aim of this study was to compare the level of 8-isoPGF2-alpha in saliva in patients with and without metal dental restorations. Material and Methods: 35 patients were divided in two groups according to the presence or absence of metal dental objects. Non-stimulated and stimulated saliva samples were collected. The concentration of 8-isoPGF2-alpha was measured by liquid chromatography tandem mass spectrometry. For statistical analysis non-parametric Mann-Whitney test, Kruskal Wallis test, and Wilcoxon signed-rank test were applied. Results: There was a significant difference in the concentration of 8-isoPGF2-alpha between the samples of non-stimulated and stimulated saliva. The concentration of 8-isoPGF2-alpha in non-stimulated saliva in patients with metal dental restorations was significantly higher than the one in the group of patients without metal objects. Conclusions: The presence of metal dental restorations increases the concentration of 8-isoPGF2-alpha in non-stimulated saliva. Key words:Saliva, dental metal restorations, oxidative stress.

Recent Advances in 3D Printing of Polymers for Application in Prosthodontics.

Contemporary mass media frequently depict 3D printing as a technology with widespread utilization in the creation of dental prosthetics. This paper endeavors to provide an evidence-based assessment of the current scope of 3D printing's integration within dental laboratories and practices. Its primary objective is to offer a systematic evaluation of the existing applications of 3D-printing technology within the realm of dental prosthetic restorations. Furthermore, this article delves into potential prospects, while also critically examining the sustained relevance of conventional dental laboratory services and manufacturing procedures. The central focus of this article is to expound upon the extent to which 3D printing is presently harnessed for crafting dental prosthetic appliances. By presenting verifiable data and factual insights, this article aspires to elucidate the actual implementation of 3D printing in prosthetic dentistry and its seamless integration into dental practices. The aim of this narrative review is twofold: firstly, to provide an informed and unbiased evaluation of the role that 3D printing currently plays within dental laboratories and practices; and secondly, to instigate contemplation on the transformative potential of this technology, both in terms of its contemporary impact and its future implications, while maintaining a balanced consideration of traditional dental approaches.

Comparative analysis of tensile strength between three types of retraction cords.

INTRODUCTION: Gingival retraction is the withdrawal of the marginal gingiva away from the tooth. This procedure creates a space between the prepared tooth and the gingival tissues to catch more fine details of the impression material. The most common retraction device used in clinical practice is the retraction cord.

Development and validation of an LC-MS/MS method for determination of 8-iso-prostaglandin f2 Alpha in human saliva.

Background: Increased formation of reactive oxygen species may be caused by the ion release of the metal alloys used in prosthetic dental restorations due to the corrosion process. As products of lipid peroxidation, isoprostanes can be used as a marker for oxidative stress in the body. There are two significant advantages of using isoprostanes as an oxidative stress marker - presence in all fluids in the body and low reactivity. Saliva provides noninvasive, painless, and cost-effective sample collection and can be used as an alternative testing medium of blood and urine. Methods: This study presents the development and validation of a sample LC-MS/MS method to quantify 8-isoprostaglandin F2-a in human saliva using salt-out assisted liquid-liquid extraction (SALLE). Results: The selected sample preparation procedure optimized chromatographic separation and mass detection provided high recovery and sensitivity of the analysis. The calibration curve was obtained in the predefined range 25-329 ng/L with R2 larger than 0.995. Normalized matrix varied between 89.7 % and 113.5%. The method showed sufficient accuracy and precision - accuracy in the range 89.7 %-113.9 %, and precision between 2.3% and 5.4%. Conclusions: The proposed method is validated according to current EMA/FDA industrial guidance for bioanalysis and offers an appropriate level of sensitivity and sufficient accuracy and precision.

Histological Gingival Assessment after Conventional and Laser Gingivectomy.

BACKGROUND: Gingivectomy is a procedure often performed in everyday clinical practice using numerous instruments. AIM: To evaluate and compare the gingival cut surface after gingivectomy with 6 different surgical instruments - a surgical scalpel, an Er:YAG laser, a CO2 laser, a ceramic bur, an electrocautery device, and a diode laser. MATERIALS AND METHODS: Gingivectomy using the above listed instruments was performed in 18 patients. The histological samples excised with a surgical scalpel were assigned as a control group and the other five types - as test groups. The following histological parameters were measured: coagulation layer thickness (in µm); presence or absence of a microscopic rupture and presence or absence of hemostasis in-depth. RESULTS: The best instrument of the above listed ones which demonstrated excellent results is the CO2 laser. The Er:YAG laser has a thin coagulation layer and lack of hemostasis in-depth. The diode laser has the widest coagulation layer which is an advantage from a clinical point of view. Electrocautery proved to be as effective as the diode laser, but it should not be used around metal restorations. The ceramic bur has less pronounced hemostasis in-depth. CONCLUSIONS: Modern dentistry uses a wide variety of methods that are designed to be applied in everyday practice. Good knowledge of the ways to use them, their advantages and disadvantages is essential to obtaining the optimal result depending on the clinical case.

A new method for photodynamic disinfection of prosthetic constructions and impressions in prosthetic dentistry.

INTRODUCTION: Photodynamic therapy is a topical treatment of pathogens that involves the use of a photoactive dye (photosensitizer), which is non-toxic when not exposed to light and activated by light of a specific wavelength in the presence of oxygen. The highly cytotoxic oxygen species generated by the induced photophysical processes inactivate the pathogenic cells. The PURPOSE of this study was to present a new method we developed for photodynamic disinfection of prostheses and impressions in prosthetic dentistry and to assess its effectiveness in comparison with some conventional methods of disinfection. MATERIALS AND METHODS: The method was developed on the basis of series of experimental studies (30 experiments for each type of disinfectant, 30 controls with no disinfection for each material, and 30 direct cultures of each test microorganism--MRSA, P. aeruginosa and C. albicans) using standard test specimens made of prosthesis plastic and impression materials. RESULTS: The new method of photodynamic disinfection with GaPc1 as photosensitizer was 100% efficient in C-silicones, A-silicones and polyethers, but not in alginates (40%). To plastics the photodynamic method shows the same efficiency as the conventional disinfectants of hypochlorite solutions and denture cleansing tablets (100% effect). CONCLUSION: The method of photodynamic disinfection we developed is a good therapeutic choice against orally transmitted diseases in prosthetic dentistry.