Dental ceramic damage associated with incorrect laboratory procedures.

Ceramic is a commonly used material in dentistry for reconstructing missing teeth or their tissues due to its biocompatibility, durability and excellent esthetic properties. Despite these advantages, the ceramic restoration damage remains a significant clinical problem. Its causes can be divided into clinical and laboratory factors. The most known include uneven occlusion, improper preparation, trauma, or parafunctions. This study focuses on characterizing less known laboratory causes of ceramic restoration damage. We reviewed the current literature available in the PubMed and Scopus databases. On the basis of 63 selected studies, 3 basic causes of damage were identified: excessive stresses between the framework and ceramic veneering, poor quality of the connection between the facing layer and the substructure, and defects resulting from the nature of the ceramic material such as defects in the ceramic layer, brittleness and lack of flexibility. The stages of the manufacturing process of various permanent ceramic restorations were presented. By controlling these procedures, we can eliminate the errors, resulting in long-term effective functioning of the ceramic restorations.

Anatomical features of the mandibular canal and their clinical significance - review of literature.

The clinical issues related to the anatomical variation of the mandibular canal have been extensively analyzed since the 19th century. Evolving dentistry techniques and advancements in the prosthetics forced to collect detailed information about anatomical variations of the mandibular canal due to its neurovascular content. Therefore, its radiographic imaging became an essential part of the oral surgery, in order to avoid complications resulted from an accidental damage of the mandibular canal.

The Impact of Sintering Technology and Milling Technology on Fitting Titanium Crowns to Abutment Teeth-In Vitro Studies.

INTRODUCTION: The aim of the study is to evaluate the marginal and internal fit of titanium alloy (Ti6Al4V) crowns using the Selective Laser Melting (SLM) method and CAD/CAM milling. MATERIALS AND METHODS: The research materials are abutment teeth and prosthetic crowns. The method is based on scanning the abutments and the interior of the substructures, creating their 3D models, using the program for comparison, and determining error maps of fitting crowns to the reference models, in the form of positive and negative deviations. Adding the deviations gives information about the tightness of the crowns. The Shapiro-Wilk test and the one-way ANOVA analysis were performed. The level of significance was p = 0.05. RESULTS: The crowns made in SLM, a slightly better internal fit was found than for milled crowns, as well as a comparable marginal fit. The mean deviations for the sintering were the values [mm]: -0.039 and +0.107 for tooth 15 and -0.033 and +0.091 for tooth 36, and for the milling -0.048 and +0.110 for tooth 15 and -0.038 and +0.096 and for tooth 36. CONCLUSION: Based on the research conducted and the experience in therapeutic procedures, it can be indicated that the fitting of titanium alloy crowns in SLM and milling meets the clinical requirements. To evaluate the technology, a method was developed that determines the accuracy of mapping the shape of the tooth abutments in the crown substructures for the individual conditions of the patient.

Strength Tests of Alloys for Fixed Structures in Dental Prosthetics.

The production of fixed prosthetic restorations requires strength identification in terms of cognition and the targeted clinical applications. The aim of the study is to evaluate the static strength in axial tensile and compression tests of titanium and cobalt alloys for the supporting foundations of crowns and bridges produced using Computer Aided Design and Manufacturing (CAD/CAM) technologies: Direct Metal Laser Sintering (DMLS) and milling. The test materials are samples of Ti6Al4V and CoCrMo alloys obtained using digital technologies and, for comparison purposes, CoCrMo samples from traditional casting. For the studied biomedical alloys, R0.05, Rp0.2, Rm and Ru were determined in the tensile tests, and in the compression tests R0.01, Rp0.2 and the stress σ at the adopted deformation threshold. Tensile and compression tests of titanium and cobalt alloys indicate differences in strength parameters resulting from the technology applied. The manufacturing of the structures by DMLS provides the highest stress values that condition elastic deformations for cobalt biomaterials: R0.05 = 1180 MPa, R0.01 = 1124 MPa and for titanium biomaterials: R0.05 = 984 MPa, R0.01 = 958 MPa. The high resistance to deformation of CoCrMo and Ti6Al4V from DMLS may be beneficial for fixed prosthetic structures subjected to biomechanical stresses in the stomatognathic system and the impact of these structures on the dento-alveolar complex.

The effect of root canal rinsing protocol on the push-out bond strength to the dentin cementation of the fiber post.

B a c k g r o u n d: Studies on the effect of root canal rinsing protocols on fiber post bonding to dentin are inconclusive. This study reports investigation of this topic. O b j e c t i v e s: to determine effects of irrigation protocol by means of a push-out test on the strength of adhesion between the post and dentin in an in vitro study. Materials and Method: Thirty human single-rooted teeth were prepared using hand instruments and the step-back technique, filled with gutta-percha, sealed with AH Plus (Dentsply), and divided into three groups: A: rinsed with NaCl; B: rinsed with 2% chlorhexidine (CHX); C: not rinsed before cementation of posts. The fiber posts were set using RelyX and Built-it. The tooth roots were sliced and the push-out test was performed. The area of contact between the post and dentin was calculated and the destroying force was established. The results were statistically analyzed. R e s u l t s: The mean adhesive strength was 10.69 MPa in group A, 16.33 MPa in group B, and 16.72 MPa in C. The adhesive strength in group B and C was statistically significantly higher than in group A (p = 0.0016, ANOVA). Conclusion: Rinsing root canals with CHX seems to be the most effective method prior to setting a fiber post.

The role of serial carotid intima-media thickness assessment as a surrogate marker of atherosclerosis control in patients with recent myocardial infarction.

INTRODUCTION: Despite percutaneous coronary intervention (PCI), patients after their first myocardial infarction (MI) are at high risk of ischemic event recurrence. Therefore, there is a need for objective markers of adequate atherosclerosis control, independent of prescribed pharmacotherapy and patients' compliance. Such a potential indicator of major adverse cerebral and coronary event (MACCE) risk might be change in carotid intima-media thickness (CIMT), which indicates atherosclerosis growth. AIM: To evaluate the potential associations between CIMT changes and the incidence of MACCE and recurrent MI. MATERIAL AND METHODS: The CIMT assessments at baseline and during 2 follow-up visits were performed in 215 patients admitted with MI, in whom PCI was performed for an index lesion, followed by best medical treatment. The incidences of MACCE (cardiovascular death, recurrent MI, ischemic stroke) and new onset angina were recorded prospectively. RESULTS: The MACCE were recorded in 65 (30.2%) patients and angina due to coronary lesion progression (CLP) in 27 (12.5%) patients. Although initial CIMT values were similar in patients who suffered MACCE vs. MACCE-free patients (1.43 ±0.40 vs. 1.45 ±0.44 mm; p = 0.486), patients in whom MACCE occurred had greater annual CIMT growth as assessed at the first (0.024 ±0.12 vs. 0.009 ±0.16 mm/year; p < 0.001) and subsequent follow-up visit (0.050 ±0.1 vs. 0.001 ±0.1 mm/year; p < 0.001), in mean 36.5 ±29.3 and 53.3 ±37.1 months, respectively. An optimal cut-off value for annual CIMT change of > 0.003 mm/year (sensitivity: 84.5%, specificity: 49.3%) for MI plus CLP (AUC = 0.673) occurred an independent indicator of MACCE (HR = 3.00; 95% CI: 1.496-6.016), recurrent MI (HR = 4.59, 95% CI: 1.591-13.217), and MI plus CLP (HR = 3.50, 95% CI: 1.759-6.964). CONCLUSIONS: Annual CIMT change might be a potentially valuable marker of atherosclerosis response to post-MI treatment.

The Evaluation of Anthropometric Measurements of Young Polish Women's Faces.

Face proportions are under constant evaluation during prosthetic or surgical diagnostics and treatment. The aim was to evaluate the proportions of the faces of young Polish women as compared with other ethnic groups. MATERIALS AND METHODS: The evaluation included 60 photographs of the faces of women, average age 17.9 years. En face images were made with the camera lens situated at the same distance from the photographed subjects. Using Adobe Photoshop software, midsaggital and even anthropometric points were determined in the photographs and then the distance between these points was measured. Four relationships between vertical measurements, 3 between horizontal measurements, and 4 proportions between vertical and horizontal measurements were calculated. The results were evaluated in comparison with the golden ratio (1.618) and the measurements performed for native Americans and Latin American beauty contests winners described in the relevant literature. RESULTS: The result for the average vertical face proportion value of the examined women was close to the golden ratio (GR) and amounted to 1.592 for the proportions between nasion-stomion and stomion-gnation (98% of GR) and 1.372 for nasion-subnasale and subnasale-gnation (85% of GR).Average measurement results for young Polish women's faces were not statistically significantly different for 6 out of 11 relationships under evaluation as compared with the population of native American females and only 2 face proportions were the same as for beauty contests winners from Latin America. CONCLUSION: Face proportions of young Polish women were different from those of the females living in the American continent.

Prospective study on the prognostic value of repeated carotid intima-media thickness assessment in patients with coronary and extra coronary steno-occlusive arterial disease.

INTRODUCTION It is debatable whether the rate of change in carotid intima­media thickness (CIMT) may be used as a risk indicator of major adverse cerebral and coronary events (MACCEs) in patients with either coronary (CAD) and peripheral artery disease (PAD). OBJECTIVES This prospective study aimed to evaluate the association between CIMT changes and the incidence of MACCEs, in patients with symptomatic CAD and PAD. PATIENTS AND METHODS The study comprised 466 patients admitted with steno­occlusive disease, in whom revascularization was performed for an index lesion. Group 1 included 305 subjects with CAD, and group 2, 161 patients with PAD. CIMT was measured at baseline and at a median of 21 and 41 months afterwards. The incidence of MACCE, cardiovascular death (CVD), myocardial infarction (MI), and ischemic stroke was recorded prospectively during 5 years. RESULTS CIMT increased with a mean (SD) progression rate of 0.027 (0.16) mm/y in group 1 and 0.026 (0.17) mm/y in group 2 (P = 0.89). CIMT regression was recorded in 112 patients (36.7%) and 61 patients (37.9%) in groups 1 and 2, respectively, at baseline (P = 0.80), and 82 patients (26.9%) and 42 patients (26.1%) in groups 1 and 2, respectively, in follow­up (P = 0.85). Maintained CIMT regression was independently associated with a reduced risk of MACCEs (hazard ratio [HR], 0.25; 95% CI, 0.15-0.42), MI (HR, 0.32; 95% CI, 0.20-0.51), ischemic stroke (HR, 0.29; 95% CI, 0.18-0.45), and CVD (HR, 0.24; 95% CI, 0.15-0.40), while the CIMT progression rate of 0.056 mm/y was associated with an increased risk of MACCEs (sensitivity, 53.2%; specificity, 72.2%; area under the receiver operating curve, 0.65). CONCLUSIONS Maintained CIMT regression is associated with 68% to 75% reduction in the risk of a cardiovascular event. However, a long­term maintained CIMT regression is achieved in one­fourth of patients with either CAD or PAD.

The evaluation of the effect of carbon dioxide laser radiation on dentine tissue.

of this study was to analyze the effects of carbon dioxide (CO2) laser light on the structure and elemental composition of dentine. METHODS: The evaluation was conducted on samples from extracted teeth. The surface of the dentine was exposed to the radiation from a CTL 1401 CO2 laser (Centre of Laser Technology, Poland). The radiation and frequency parameters were as follows: group I with 5 W and 1 Hz, group II with 10 W and 1 Hz, group III with 5 W and 5 Hz, and group IV with 10 W and 5 Hz. The altered dentine structure was macroscopically and microscopically evaluated using a Nova NanoSEM 200 Scanning Electron Microscope (FEI Europe) with integrated microanalysis X-ray system for elemental analysis in points. RESULTS: There were significant differences between groups in the macro- and microstructure of laser defects. CONCLUSIONS: CO2 laser radiation causes irreversible, destructive changes in dentine. The structural dentine lesions developed under the influence of the CO2 laser radiation may hinder proper adhesion of bonding systems with the damaged tissue. Laser defects in the structure should be treated like defects of noncarious origin requiring preparation and filling with composite materials in accordance with the procedures.

The Prevalence of TMD in Polish Young Adults.

PURPOSE: The prevalence of temporomandibular disorders (TMD) in the general Polish population has not yet been thoroughly investigated. The aim of this study was to determine how frequently Polish young adults demonstrated the signs and symptoms of TMD, and how often they were aware of these. MATERIALS AND METHODS: The study involved 260 volunteers of approximately 18 years of age (and with an F:M ratio of 2.8), who had completed the Research Diagnostic Criteria for Temporomandibular Disorders (RDC/TMD) questionnaire in its internationally accepted Polish version. The volunteers were students from three randomly selected high schools in Kraków, Poland. Following the clinical examinations, all participants received none or one or more of the RDC/TMD axis I diagnoses on one or both sides: muscle disorders (group I), disk displacements (group II), arthralgia, osteoarthritis, and osteoarthrosis (group III). Classification on RDC/TMD axis II involved pain-related impairment (Graded Chronic Pain Severity, from 0: no TMD pain in the prior 6 months, to IV: high disability-severely limiting), depression, and somatization levels (normal, moderate, severe). RESULTS: On the RDC/TMD axis I, 69 (26.5%) of the participants received one or more of the possible diagnoses. Awareness of TMD was present in 20 (7.7%) people from that group, in the form of self-complaints. The difference between females and males was statistically significant (p  = 0.0013). On the RDC/TMD axis II assessment, a diagnosis of pain, depression, or somatization was given in 38 (14.6%) cases from that group. CONCLUSION: Muscle disorders were most frequently diagnosed in the group of Polish young adults, and the prevalence of the disease did not differ across similar groups of young people.

The evaluation of the accuracy of shape imaging of prosthetic abutment.

PURPOSE: The aim of the study was the in vitro evaluation of the accuracy of shape imaging of abutment teeth using different impression compounds. METHODS: To compare the accuracy of the shape of the numerically imaged real prosthetic abutments with the tested models of abutments obtained with the replica technique, the Geomagic Qualify program was applied. Making use of the licensed program Statistica, statistical analysis of the results obtained was conducted. RESULTS: In the research procedures, analyses were conducted for 10 abutment premolars and 10 abutment molars. The tests allowed us to state that the dimensional accuracy of the models of prosthetic abutments obtained with the application of elastic compounds tested ensures comparable shape imaging. CONCLUSIONS: The objective method developed and applied here is suitable for controlling the imaging of the abutment teeth. The Geomagic Qualify program that was used during the research is a reliable tool of 3D analysis for the estimation of procedure of abutment tooth preparation and indication of an error of shape of prepared occlusal surface, lateral surface of abutment and errors of shaping the chamfer zone.

Microstructural and micromechanical tests of titanium biomaterials intended for prosthetic reconstructions.

PURPOSE: The aim of the present paper was a question of structural identification and evaluation of strength parameters of Titanium (Ticp - grade 2) and its alloy (Ti6Al4V) which are used to serve as a base for those permanent prosthetic supplements which are later manufactured employing CAD/CAM systems. METHODS: Microstructural tests of Ticp and Ti6Al4V were conducted using an optical microscope as well as a scanning microscope. Hardness was measured with the Vickers method. Micromechanical properties of samples: microhardness and Young's modulus value, were measured with the Oliver and Pharr method. RESULTS: Based on studies using optical microscopy it was observed that the Ticp from the milling technology had a single phase, granular microstructure. The Ti64 alloy had a two-phase, fine-grained microstructure with an acicular-lamellar character. The results of scanning tests show that titanium Ticp had a single phase structure. On its grain there was visible acicular martensite. The structure of the two phase Ti64 alloy consists of a ß matrix as well as released α phase deposits in the shape of extended needles. Micromechanical tests demonstrated that the alloy of Ti64 in both methods showed twice as high the microhardness as Ticp. In studies of Young's modulus of Ti64 alloy DMLS technology have lower value than titanium milling technology. CONCLUSIONS: According to the results obtained, the following conclusion has been drawn: when strength aspect is discussed, the DMLS method is a preferred one in manufacturing load structures in dentistry and may be an alternate way for the CAD/CAM system used in decrement processing.

Dentinogenesis imperfecta - hardness and Young's modulus of teeth.

Dentinogenesis imperfecta type II (DI-II) is the most common dental genetic disease with reported incidence 1 in 8000. Elasticity and hardness of the enamel of teeth are important values which are connected with their resistance to attrition. It is hypothesized that values of physical properties for healthy teeth and teeth with DI-II are different. The aim of the study was to investigate some physical properties of teeth extracted from patients with DI-II in comparison with normal teeth. The material of the study was six teeth: three lower molars, with clinical signs of DI-II, which were extracted due to complications of pulp inflammation and three other lower molars which were extracted for orthodontic reasons - well formed, without any signs of pathology. The surfaces of DI-II and normal teeth were tested on the CSM Instruments Scratch Tester machine (producer CSEM Switzerland) by Oliver and Pharr method. The indenter used was Vicker's VG-73 diamond indenter. Additionally, the Scanning Electron Microscopy (SEM) analysis of the surface of the teeth with DI-II was made. Vickers hardness of the teeth with dental pathology (DI-II) was seven times smaller, and Young's modulus six times smaller than those of healthy teeth. The parameters of hardness and elasticity of enamel of teeth with clinical diagnosis of DI-II were very much smaller than in normal teeth and because of that can be responsible for attrition.

Mycological analysis of the oral cavity of patients using acrylic removable dentures.

Background. The problems of fungal infections in edentulous have been discussed in literature. Findings show that oral mycosis has an influence on the mycosis of oesophageal mucosa. Based on this we started to follow from 2007 in patients who wear dentures mycological examination, to evaluate changes of yeasts numbers, the sensitivity to antibiotics and determine the impact of types of prosthesis, time of using, gender and age of patients. 1230 patients who were wearing dentures participated in the retrospective study. The material for mycological examination was sampled as a smear from the palate. After the mycological identification of Candida species and assessment of growth, the susceptibility testing with Fluconazole and Nystatin was made. The number of 23 Candida species was diagnosed microbiologically in five years. C. albicans and C. glabrata were increasing in number-from 33,7% to 46,9% and 6,7% to 14,0%, respectively. There was a significant statistical difference between yeasts growth and gender (P = 0, 017 < 0.05). The conclusion is that a large percentage of persons wearing removable denture has been affected by Candida species and that could lead to the mycosis of farther gastrointestinal tract sections. The mycological examination before treatment, especially in patients using acrylic denture, appears to be necessary.