Fully digital workflow for retrofitting a new crown to an existing removable partial denture.

A fully digital technique for retrofitting a new crown to a removable partial denture (RPD) is presented. The conventional crown preparation was followed by intraoral scanning of the preparation, the antagonists, and the occlusal relationship and by scanning the RPD both in situ and outside the oral cavity. All the standard tessellation language (STL) files were indexed in a design software program, and the new crown was designed. After conventional dynamic adaptation against the antagonist teeth in the software program, the existing RPD was designated as the antagonist cast, and a second regular static adaptation was performed. This straightforward approach produced a crown which fit the occlusal rest and reciprocating arm without sending the existing prosthesis to the dental laboratory.

The Yin and Yang dualistic features of autophagy in thermal burn wound healing.

Burn healing should be regarded as a dynamic process consisting of two main, interrelated phases: (a) the inflammatory phase when neutrophils and monocytes infiltrate the injury site, through localized vasodilation and fluid extravasation, and (b) the proliferative-remodeling phase, which represents a key event in wound healing. In the skin, both canonical autophagy (induced by starvation, oxidative stress, and environmental aggressions) and non-canonical or selective autophagy have evolved to play a discrete, but, essential, "housekeeping" role, for homeostasis, immune tolerance, and survival. Experimental data supporting the pro-survival roles of autophagy, highlighting its Yang, luminous and positive feature of this complex but insufficient explored molecular pathway, have been reported. Autophagic cell death describes an "excessive" degradation of important cellular components that are necessary for normal cell function. This deadly molecular mechanism brings to light the darker, concealed, Yin feature of autophagy. Autophagy seems to perform dual, conflicting roles in the angiogenesis context, revealing once again, its Yin-Yang features. Autophagy with its Yin-Yang features remains the shadow player, able to decide quietly whether the cell survives or dies.

Compressive and Flexural Strength of 3D-Printed and Conventional Resins Designated for Interim Fixed Dental Prostheses: An In Vitro Comparison.

A provisionalization sequence is essential for obtaining a predictable final prosthetic outcome. An assessment of the mechanical behavior of interim prosthetic materials could orient clinicians towards selecting an appropriate material for each clinical case. The aim of this study was to comparatively evaluate the mechanical behavior-with compressive and three-point flexural tests-of certain 3D-printed and conventional resins used to obtain interim fixed dental prostheses. Four interim resin materials were investigated: two 3D-printed resins and two conventional resins (an auto-polymerized resin and a pressure/heat-cured acrylic resin). Cylindrically shaped samples (25 × 25 mm/diameter × height) were obtained for the compression tests and bar-shaped samples (80 × 20 × 5 mm/length × width × thickness) were produced for the flexural tests, observing the producers' recommendations. The resulting 40 resin samples were subjected to mechanical tests using a universal testing machine. Additionally, a fractographic analysis of failed samples in bending was performed. The results showed that the additive manufactured samples exhibited higher elastic moduli (2.4 ± 0.02 GPa and 2.6 ± 0.18 GPa) than the conventional samples (1.3 ± 0.19 GPa and 1.3 ± 0.38 GPa), as well as a higher average bending strength (141 ± 17 MPa and 143 ± 15 MPa) when compared to the conventional samples (88 ± 10 MPa and 76 ± 7 MPa); the results also suggested that the materials were more homogenous when produced via additive manufacturing.

Bending Fracture of Different Zirconia-Based Bioceramics for Dental Applications: A Comparative Study.

The fabrication of fixed dental prostheses using aesthetic materials has become routine in today's dentistry. In the present study, three-unit full zirconia fixed prosthetic restorations obtained by computer-aided design/computer-aided manufacturing (CAD/CAM) technology were tested by bending trials. The prostheses were intended to replace the first mandibular left molar and were manufactured from four different types of zirconia bioceramics (KatanaTM Zirconia HTML and KatanaTM Zirconia STML/Kuraray Noritake Dental Inc.; NOVAZir® Fusion float® ml/NOVADENT/Dentaltechnik; and 3D PRO Zirconia/Bloomden Bioceramics). In total, sixteen samples were manufactured-four samples per zirconia material. Additionally, the morphology, grain size area distribution, and elemental composition were analyzed in parallelepiped samples made from the selected types of zirconia in three different areas, noted as the upper, middle, and lower areas. The scanning electron microscope (SEM) analysis highlighted that the grain size area varies with respect to the researched area and the type of material. Defects such as microcracks and pores were also noted to a smaller extent. In terms of grain size area, it was observed that most of the particles in all samples were under 0.5 µm2, while the chemical composition of the investigated materials did not vary significantly. The results obtained after performing the bending tests showed that a zirconia material with fewer structural defects and an increased percentage of grain size area under 0.5 µm2, ranging from ~44% in the upper area to ~74% in the lower area, exhibited enhanced mechanical behavior. Overall, the resulting values of all investigated parameters confirm that the tested materials are suitable for clinical use.

ILs and MMPs Levels in Inflamed Human Dental Pulp: A Systematic Review.

A wide range of mediators are released from the pulp tissue because of bacterial invasion which causes inflammation. Interleukins (ILs) and matrix metalloproteinases (MMPs) have a leading role in initiating and spreading of inflammation because of their synergic action. Biomarkers such as ILs and MMPs can be identified via several methods, establishing the inflammatory response of the dental pulp. The aim of this systematic review is to evaluate the levels of ILs and/or MMPs in human dental pulp. PubMed, OVID, Cochrane, Scopus, Web of Science and Wiley online library databases were searched for original clinical studies. After applying inclusion and exclusion criteria, a quality assessment of studies was performed based on a modified Newcastle-Ottawa scale. In the review were included articles that evaluated the presence of ILs and/or MMPs in pulp tissue using enzyme-linked immunosorbent assay (ELISA) or western blot or multiplex assay. Six articles were included in the present synthesis. Although various diagnostic methods were used, statistically significant higher levels of ILs and/or MMPs were mostly found in the experimental groups compared to healthy pulp samples. The biomarkers studied can be a promising tool to evaluate pulp tissue health or even in pulpitis treatment.

Biochemical Interaction between Materials Used for Interim Prosthetic Restorations and Saliva.

The purpose of this study was to analyze the oxidative stress level and inflammatory status of saliva in the presence of certain materials used for obtaining interim prosthetic restorations. Four types of interim resin materials were investigated: a pressure/heat-cured acrylic resin (Superpont C+B, SpofaDental a.s Czech Republic, /KaVo Kerr Group), a milled resin (Telio CAD polymethyl methacrylate, Ivoclar Vivadent AG, Liechtenstein), a 3D printed resin (NextDent C&B MFH, NextDent by 3D Systems, the Netherlands), and a pressure/heat-cured micro-filled indirect composite resin (SR Chromasit, Ivoclar Vivadent AG, Liechtenstein). The disk-shaped resin samples (30 mm diameter, 2 mm high) were obtained in line with the producers' recommendations. The resulting resin specimens were incubated with saliva samples collected from twenty healthy volunteers. In order to analyze the antioxidant activity of the tested materials, certain salivary parameters were evaluated before and after incubation: uric acid, gamma glutamyl transferase (GGT), oxidative stress responsive kinase-1 (OXSR-1), and total antioxidant capacity (TAC); the salivary levels of tumor necrosis factor (TNFα) and interleukin-6 (IL-6) (inflammatory markers) were measured as well. The obtained results are overall favorable, showing that the tested materials did not cause significant changes in the salivary oxidative stress level and did not influence the inflammatory salivary status.

A Review on the Biocompatibility of PMMA-Based Dental Materials for Interim Prosthetic Restorations with a Glimpse into their Modern Manufacturing Techniques.

This paper's primary aim is to outline relevant aspects regarding the biocompatibility of PMMA (poly(methyl methacrylate))-based materials used for obtaining interim prosthetic restorations, such as the interaction with oral epithelial cells, fibroblasts or dental pulp cells, the salivary oxidative stress response, and monomer release. Additionally, the oral environment's biochemical response to modern interim dental materials containing PMMA (obtained via subtractive or additive methods) is highlighted in this review. The studies included in this paper confirmed that PMMA-based materials interact in a complex way with the oral environment, and therefore, different concerns about the possible adverse oral effects caused by these materials were analyzed. Adjacent to these aspects, the present work describes several advantages of PMMA-based dental materials. Moreover, the paper underlines that recent scientific studies ascertain that the modern techniques used for obtaining interim prosthetic materials, milled PMMA, and 3D (three-dimensional) printed resins, have distinctive advantages compared to the conventional ones. However, considering the limited number of studies focusing on the chemical composition and biocompatibility of these modern interim prosthetic materials, especially for the 3D printed ones, more aspects regarding their interaction with the oral environment need to be further investigated.

Salivary biomarkers: relationship between oxidative stress and alveolar bone loss in chronic periodontitis.

OBJECTIVES: Oxidative stress is implicated in the pathogenesis of many systemic and oral diseases such as periodontal disease. The main aim of this study is to explore a possible association between salivary markers of OS and alveolar bone loss. MATERIALS AND METHODS: The study included 20 patients with chronic periodontitis and 20 controls. Salivary OS biomarkers 8-hidroxy-desoxguanosine (8-HOdG), malondialdehyde (MDA), uric acid, total antioxidant capacity (TAC) and glutathione peroxidase (GPx) were evaluated. Bone loss markers such as C-terminal telopeptide of type I collagen (CTX I), matrix metalloproteinases-8 (MMP-8), osteocalcin and 25-hydroxy vitamin D3 (25- OH D) were detected in this study. The methods included general biochemical tests and ELISA. RESULTS: Salivary 8-OHdG, MDA levels were significantly higher in the chronic periodontitis group compared with controls (p < 0.05). Salivary activities for uric acid, TAC and GPx were significantly decreased in patients with chronic periodontitis vs controls (p < 0.05). Salivary levels for CTX I, MMP-8, 25-OH D and Osteocalcin were significantly higher in the chronic periodontitis group compared to the controls (p < 0.05). A significant positive correlation was observed between salivary levels of MDA and CTX I. Significant negative correlations between uric acid and CTX I and between MMP-8 and uric acid have been found. Significant positive correlations were observed between CTX I, MMP-8, 25-OH D, osteocalcin and clinical parameters of periodontal disease. CONCLUSIONS: Important oxidative stress associated with alveolar bone loss biomarkers can be detected in saliva of patients with periodontal disease.

Saliva--a diagnostic window to the body, both in health and in disease.

Saliva, the most available and non-invasive biofluid of the human body, permanently "bathes" the oral cavity and is trying to cope with an ever-changing milieu. The oral cavity, a very complex and unique milieu due to its dual function, is the only place in the body where the mineralized tissue is exposed to the external environment in which there are complex interactions between various surfaces: host soft and hard tissues, food, air, and microorganisms. Saliva includes a large number of inorganic and organic compounds, which act as a "mirror of the body's health." In addition to its other functions, saliva could constitute the first line of defense against oxidative stress. Due to its composition and functions, saliva could have a significant role in controlling and/or modulating oxidative damages in the oral cavity. As a diagnostic fluid, saliva offers distinctive advantages over serum. Furthermore, saliva may provide a cost-effective approach for the screening of large populations. Gland-specific saliva can be used for diagnosis of pathology specific to one of the major salivary glands. Whole saliva, however, is most frequently used for diagnosis of systemic diseases. As we enter the era of genomic medicine, sialochemistry will play an increasingly important role in the early detection, the monitoring and progression of the systemic and oral diseases. We reviewed the current data within literature and of our research concerning clinical potential of the saliva.

Cigarette smoke effect on total salivary antioxidant capacity, salivary glutathione peroxidase and gamma-glutamyltransferase activity.

Saliva is the first biological fluid that inhaled cigarette smoke (CS) encounters. CS contains several carcinogens known to initiate and promote tumourigenesis and metastasis. One of the aims of this study was to establish if glutathione peroxidase and gamma-glutamyltranspherase (GGT) could be used as possible markers for evaluating the oral oxidative stress caused by smoking. The effect of CS on free radical generation was investigated using two methods. Using different assays, different antioxidants present in saliva may be evidenced due to the different principles on which they are based. Our results indicate that exposure to CS caused a statistically significant decrease of both salivary glutathione peroxidase (p < 0.01) and salivary GGT (p < 0.01). We also found that exposure to CS caused a statistically significant decrease of salivary total antioxidant status (p < 0.01). Such decreases may have a consistent role in the mechanisms by which the toxic effects of CS initiate oral inflammatory diseases, promote precancerous transformations, and destroy the oral cavity homeostasis. Therefore the evaluation of total antioxidant capacity of saliva is important but it must be done together with the evaluation of salivary specific markers of oxidative stress, such as uric acid, albumin and possibly, GGT.

Effect of gas phase and particulate phase of cigarette smoke on salivary antioxidants. What can be the role of vitamin C and pyridoxine?

The effect of smoking is in our days a serious global public health problem of major concern. Incidence of oral squamous cell carcinoma (SCC) in cigarette smokers is four to seven times higher than in nonsmokers. There is a constant and direct attack of various cigarette smoke constituents on the oral epithelial cells, which gradually accumulate and cause malignant transformation. Saliva is the first biological fluid that encounters inhaled cigarette smoke (CS). We have studied the influence of CS on salivary antioxidant capacity, uric acid, amylase and LDH (lactate dehydrogenase). In our study both, gas and particulate phase of CS were tested separately, and possible antioxidant effect of pyridoxine on salivary components was examined. Our results indicate that exposure to both, gas and particulate phase of CS caused a statistically significant decrease in salivary uric acid, LDH and amylase activity. We have also studied the effect of vitamin C (10 mg/dl) and vitamin B6 (1 mM) during incubation of saliva in the presence of CS. The addition of vitamin C had a significant (p < 0.05) protective effect on salivary uric acid level (0.25 +/- 0.12 for saliva incubated with gas phase of CS vs. 0.65 +/- 0.12 for saliva incubated with gas phase of CS in the presence of vitamin C). Vitamin C was not able to maintain/restore the original uric acid level. In the presence of the gas phase, pyridoxine had no protective effect, neither on salivary uric acid level nor on the FRAP activity of saliva. The purpose of our study was to discover a connection between the level of antioxidants in saliva in the presence of the two components of CS. Our results show that salivary antioxidant system is significantly and distinctly affected by both gas and particulate phase of CS and suggest that an adequate intake of antioxidants may help smokers to avoid CS-induced oxidative damage and to prevent degenerative diseases.

Salivary aspartate aminotransferase, alanine aminotransferase and alkaline phosphatase: possible markers in periodontal diseases?

BACKGROUND: Saliva can be used as a diagnostic fluid in medicine. Components of saliva proposed as disease markers include enzymes (alkaline phosphatase, esterase, glucuronidase, aminopeptidase), immunoglobulins (IgA, IgG), and hormones (steroid hormones). Many of these salivary components appeared to be useful biochemical markers of the evolution of periodontal disease, for which salivary analysis can offer a cost-effective approach for monitoring the disease. The salivary components proposed as markers for periodontal disease activity are aspartate aminotransferase (AST), alkaline phosphatase (ALP), aminopeptidases, and glucuronidases. The purpose of our study was to illustrate the influence of periodontal disease on the level of salivary AST, alanine aminotransferase (ALT) and ALP. METHODS: All clinical periodontal examinations were performed by the same periodontist. All patients included in the study presented a probing depth >5 mm, bleeding on probing and alveolar bone loss >40%. Salivary AST, ALT and ALP activities were measured using DiaSys analysis kits from Diagnostic Systems. The methods were adapted for saliva. RESULTS: Salivary AST activity in patients with periodontal disease was significantly increased (p<0.01) (median 81.75+/-23 U/L) compared with controls (15.25+/-10.5 U/L). Salivary ALT activity was not significantly modified in saliva from patients with periodontal disease compared with the control group. Our results showed a significant (p<0.01) increase in salivary ALP activity (34.38+/-1.5 U/L) in patients with periodontal disease compared with controls (6.6+/-4.2 U/L). CONCLUSIONS: Our results revealed that periodontal destruction such as periodontal pockets, gingival bleeding and suppuration are related to higher ALP and AST levels in saliva. Salivary AST could be used as a useful marker for monitoring periodontal disease. The increase in salivary ALP activity in periodontitis demonstrated could be associated with alveolar bone loss, a key feature of periodontal disease. More studies are necessary to evaluate which specific clinical, microbiological and histological characteristics of periodontal disease are associated with elevated levels of AST and ALP in saliva.