Synthesis, Processing, and Characterization of the Cobalt Alloys with Silicon Addition

The composition of the cobalt alloys contains only noncytotoxic elements (Cr, Si, and Mo) that ensure its biocompatibility, and consequently, the development and proliferation of cells at the implant/tissue interface. The cobalt alloy has an original composition with silicon addition and the proportion of the alloying elements was established so as to ensure a high biocompatibility and adequate physical-chemical characteristics for it to be used in various applications. Silicon is known to be a metal with a high biocompatibility; it can replace noble/non-noble metals in commercial alloys, thereby excluding the occurrence of any toxic corrosion products. We chose it as an alloying element because it confers good casting properties, has double role as hardener and oxidant, ensures an increase in the resistance to tear, and offers a proper fluidity in the liquid phase

Study on teeth resistance affected by fluorosis as a response to dental caries

Rezumat. Scopul studiului a fost determinarea rezistenţa la atacul carios a smalţu‑ lui şi dentinei dinţilor afectaţi de fluoroză dentară cu severităţi diferite. S‑au utilizat 40 dinţi fluorotici împărţiţi în 4 grupuri corespunzător gradului de afectare conform clasificării Thylstup‑Fejerskov. S‑a determinat rugozitatea de suprafaţă a smalţului şi dentinei prin examinare AFM. Rezultatele au fost exprimate ca variaţie relativă a rugozităţii. S‑a înregistrat o tendinţă de creş‑ tere a indicelui de rugozitate relativă la nivelul smalţului şi dentinei odată cu creşterea severităţii fluorozei dentare. S‑au obţinut rezultate semnificative statistic atunci când s‑au comparat valorile indicilor de rugozitate al nivelul smalţului în cazul dinţilor afectaţi cu fluoroză cu gradele 2, 3 şi 4 compara‑ tiv cu dinţii sănătoşi şi cu cei având gradul 1. La nivel deninar s‑au obţinut rezultate semnificative din punct de vedere statistic atunci când s‑au com‑ parat toate loturile de studiu între ele. Smalţul dinţilor afectaţi de fluoroză de gradul 1 s‑a dovedit a fi rezistent la atacul acid comparativ cu smalţul dinţilor afectaţi de fluoroză cu grade superioare. Dentina dinţilor afectaţi de fluoroză dentară s‑a dovedit cu atât mai suscetibilă la atacul carios cu cât gradul severităţii fluorozei este mai mare.Abstract. The aim of the study was to assess the susceptibility of fluorotic emanel and dentine to acid challenge. 40 fluorotic teeth having different degree of dental fluorosis according to Thylstup‑Fejerskov classification were split in 4 groups. The surface roughness of the enamel and dentine before and af‑ ter the demineralisation was calculated using AFM evaluation. The values were expressed by relative variation of roughness. The relative roughness indices for enamel and dentine increased with the increase of dental fluo‑ rosis severity. The results were analised using ANOVA and post‑hoc Bon‑ ferroni statistical tests. Significant statistical results were obtained when comparing the enamel roughness indices of the teeth having TF2, 3 and 4 and the teeth having TF0 and 1 and when comparing the dentine rough‑ ness indices for all the study groups. The enamel of healthy and TF1 teeth was significantly more resistent to acid challenge when compared with the enamel of the teeth having superior severity of dental fluorosis.The sus‑ ceptibility of the dentine to acid challenge incresed with the increase of fluorosis severity

Study regarding stepwise therapy in deep caries

Rezumat Scopul studiului. Studiul a urmărit evaluarea rezultatelor terapiei stepwise în cadrul unui lot de dinţi cu carii dentare profunde cu evoluţie acut‑progresivă. Material și metodă. Lotul de studiu a inclus 80 de dinţi cu leziuni carioase profunde acut‑progresive la un grup de 48 pacienţi cu vârste cuprinse între 15 şi 40 de ani. Au fost selectaţi dinţi la care îndepărtarea dentinei afectate ar fi condus la deschiderea camerei pulpare în cazul terapiei cariei dentare prin metoda clasică. La prima şedinţă a fost îndepărtată cu ajutorul unui excavator complet dentina periferică şi parţial dentina necrotică şi afectată localizată pe fundul cavităţii carioase. Au fost realizate, prin intermediul inspecţiei vizuale şi palpării cu sonda, evaluări standardizate ale culorii şi consistenţei dentinare. Coafajul indirect a fost realizat cu ajutorul unor materiale antiseptice, remineralizatoare şi cu rol de stimulare a depunerii de dentină terţiară: lot 1 (20 dinţi)‑hidroxid de calciu (Dycal, DeTreyDentsply), lot 2 (10 dinţi)‑ eugenat de zinc (Caryo‑ san, Spofa) şi lot 3 (10 dinţi)‑cement glassionomer (Ketac, ESPE). Rezultate. Pe parcursul terapiei stepwise are loc o modificare progresivă a culorii dentinare în galben‑brun sau brun‑închis şi modificarea consistenţei. Cele mai bune rezultate au fost obţinute prin asocierea hidroxidului de calciu cu eugenat de zinc care a asigurat o rată de succes de peste 90%. În cadrul lotului de dinţi studiat, un număr de 14cazuri (17,5%) au prezentat pierderea vitalităţii dentare şi au determinat aplicarea unei terapii endodontice. Concluzii. Rata crescută de succes după 6 luni de monitorizare demonstrează că terapia stepwise poate fi recomandată în terapia cariilor cu evoluţie acută. Hidroxidul de calciu asociat cu eugenatul de zinc este alegerea de elecţie dar, în unele situaţii clinice cu distrucţii coronare extinse, asocierea hidroxidului de calciu cu cement glassionomer poate fi considerată o alternativă viabilă.Summary Study regarding stepwise therapy in deep caries This study aimed to assess the results of stepwise excavation therapy in deep carious lesions with acute‑progressive evolution. Material and methods. The material comprised 80 teeth with deep carious lesions (acute‑progressive evolution) in a group of 48 patients which the clinicians considered would result in pulp perforation if treated by a single and terminal excavation. At the first visit excavation of the peripheral dentine was completed. The outermost part of the central and necrotic dentine was gently removed with a sharp excavator. Standardized assessments of the dentine colour and consistency were made before application of calcium hydroxide‑containing base material (Dycal, DeTreyDentsply), zinc‑oxide eugenol (Caryosan, Spofa) and glassionomer cement (Ketac, ESPE). The final excavation was completed after a treatment interval ranging from 6 weeks, 12 weeks to 24 weeks. Reassessments of the dentine colour and consistency were made before complete removal of demineralized dentine. Results. The colour of the central dentine changed to yellow‑brown or dark brown and consistency less softened. The best results were obtained with calcium hydroxide and zinc‑oxide eugenol that had a 90% succes rate. For all cases taken in study only 14 cases (17,5%) resulted in pulp perforation during the final excavation. Conclusion. The high success rate of teeth surviving the final treatment without pulp exposure after 6 months of observation shows that stepwise therapy can be recommended for deep caries with acute‑progressive evolution. Calcium hydroxide associated with zinc‑oxide eugenol must be preffered but in some cases with extensive coronal destruction glassionomer cements associated with calcium hydroxide can be a good alternative stepwise therapy

Study Regarding Neodentinogenesis, Dentinal Hypermineralisation and Pulp Calcification in Dental Caries

Introduction. The aim of study was to correlate dental-pulp reactions to dental caries with diverse localization, evolution and depth. Materials and method. The study was realized on a group of 87 patients with age ranging between 15-35 years. 222 posterior teeth with carious lesions were examined both on clinical and radiographs (ortopantomographs). Type of pulp-dentinal defensive reactions visible on radiographs were as follows: neodentinogenesis with advanced deposition of tertiary dentin, dentinal hypermineralisation, difuse pulp calcification. Parameters taken in study were as follows: sex, age group, dental group, radiographic indices (depth, location). Data were recorded in tables and expressed in Microsoft Excel graphs. Results and discussions. Clinical and radiographic data showed correlation between deep chronic caries localized on occlusal surfaces of mandibular molars and dentinal hypermineralisation reactions; deep chronic caries localized on maxillary molars were associated with massive retraction of pulp room through neodentinogenesis. Lack of pulp-dentinal complex reactions was observed especially for patients with age 15-25 and dental caries with acute evolution. Conclusions. Age, localization and evolution of dental caries can be correlated with presence of specific forms of pulp-dentinal reactions

ON THE EROSIVE EFFECT OF SOME BEVERAGES FOR SPORTSMEN UPON DENTAL ENAMEL

The aim of the study was to compare the surface morphology of enamel and the variation of the mineral ions concentration after the manifestation of the erosive effect determined by various commercial beverages for athletes. 14 premolars extracted from orthodontic reasons have been cut in two halves. On each section, an enamel surface of 3x3 mm was preserved for investigations. The samples have been divided into 4 groups. In the control group, the 7 sections were kept in artificial saliva while, in the other 3 groups, the sections were introduced in 3 beverages for athletes: Gatorade Citron (Pepsi Cola Co.), 5-hour Energy (Living Essentials), Powerade Cherry (Coca Cola Co.). The samples were analyzed on an electronic microscope with Vega II LSH scanning device, coupled with EDX Quantax QX2 detector. SEM analysis evidenced erosion zones at the level of enamel, which appears pinched in the samples subjected to the action of acid beverages. A decreasing tendency of the average values of calcium ion concentrations was observed in the batches in which the enamel samples had been subjected to the action of beverages for athletes. The highest relative variations of calcium and phosphorous ions (10%, respectively 8%) were recorded for Gatorade, followed, in decreasing order, by Powerade, for which variations of 9%, respectively 6%, were noticed, and by the 5-hour Energy beverage, in which the relative losses were of 5%, respectively 3%. All beverages for athletes tested in the present study showed erosion potential upon the dental enamel. Gatorade appeared as the most aggressive beverage for athletes followed by Powerade and 5-hour Energy

COMPARATIVE STUDY REGARDING SOURFACE ROUGHNESS OF DIFFERENT TYPES OF COMPOSITE RESINS AFTER FINISHING AND POLISHING METHODS AND GLAZE MATERIAL APPLICATION

Surface roughness is the major contributor for extrinsic discoloration of resin composite restorations. This property is closely related to the organic matrix, inorganic filler composition of the composite, and finishing and polishing procedures. Rough surface greater than 0.2 µm provides higher chances of biofilm accumulation, leading to staining and/or discoloration of the restoration’s body or margins. The purpose of the study was to compare the finishing and polishing technique of some composite resins with their sealing using a glaze material type, in terms of surface roughness. Materials and methods: 45 composite specimens were manufactured( ormocer- ADMIRA, nanohybrid – TETRIC EVOCERAM, nanocomposite – FILTEK ULTIMATE), and divided into 3 groups(n=15, control, polished and finished, and glaze material). Roughness(Ra) was messured before and after immersing in artificial saliva. For all composite resins the sourface roughness decreased after 90 days

STUDY CONCERNING THE INFLUENCE OF THE FINISHING AND POLISHING SYSTEMS ON THE SURFACE STATE OF VARIOUS TYPES OF COMPOSITE RESINS

The aim of the study was to evaluate the effect of three different one-step and two-steps polishing systems on the surface roughness of two composite resins, one with nanoparticles and one microhybrid: Filtek Supreme XT (3M ESPE) and Filtek Z 250 (3M ESPE). 35 samples (30 mm X 8 mm X 2 mm) were made from each material. 5 samples of each material were polished using the finishing long flame bur for composite resins (NTI, Kahla GmbH, Germany) without water cooling, 5 samples using the one-step abrasive rubber P20032 (NTI, Kahla GmbH, Germany) without water cooling, 5 samples using the two-steps finishing system which uses the abrasive rubbers P1932 and P19032 (NTI, Kahla GmbH, Germany). The other samples were finished with the same systems, but under water cooling. 5 non-finished and non-polished samples of each material were considered control samples. The samples surfaces were analyzed using the atomic force microscopy. The use of two-steps polishing systems led to a significantly smoother surfaces of both types of composite resins when comparing with the one-step polishing systems (Anova and Bonferroni statistical test, p<0,05). All finishing and polishing systems used in association with water led to a significantly smoother surfaces when comparing to those obtained using the same systems without water for both types of composite resins

Study Regarding The Influence Of Different Methods Used To Remove The Organic Debris On The Diagnostic Accuracy Of Diagnodent

The aim of this study was to analyse the influence of different cleaning methods of occlusal dental surfaces on the values recorded with DIAGNOdent. A number of 78 pits from 42 molars and bicusps occlusal surfaces were analysed using visual method. The cleaning of dental units was then performed using prophylactic paste Detartrine (Septodont) and rotary brush. The occlusal surfaces were assessed using DIAGNOdent. After a new cleaning of residual paste using rotary brush, the occlusal surfaces were submitted to cleaning using water/air abrasion with Prophyjet (Dentsply DETREI) and the assessment with DIAGNOdent was repeated. After the visual and laser fluorescence examination, teeth were extracted. The teeth were cut, polished and a single examiner has assessed the slices using a stereomicroscope Neophot 21. The carious lesions were classified according the 5 scores in clinical and histological examination and 4 classes in DIAGNOdent examination. The values recorded using DIAGNOdent were both influenced by tooth brushing using professional cleaning paste and water/air abrasion method. The cleaning method using toothpastes determined the highest differences on the occlusal surfaces presenting incipient enamel carious lesions. The sensitivity and specificity of laser fluorescence diagnostic method were not influenced by any cleaning method used for the removal of external organic debris

SEM STUDY OF THE INTERFACE BETWEEN THE CAVITY WALL AND COMPOSITE RESIN IN CAVITIES FILLED USING VIBRATION

Oscillation energy has been proposed in a new method to condense resin composites. The principle of this technique assumes that vibration lowers the viscosity of the resin, allowing the material to flow and easily adapt to the cavity walls, in a similar way as a flowable composite. The aim of the study was to assess the efficiency and quality of composite compaction, using one of these new devices. MATERIALS AND METHOD: The study included 20 class I cavities prepared in extracted human molars. The teeth were randomly divided into two groups of 10 cavities. Both groups were filled with composite material Filtek Z250 and the adhesive system Single Bond Plus Adhesive Adper TM Adhesive (3M ESPE).  In the control group, condensation of the composite was done with standard instruments. In the experimental group, condensation was done using a vibration instrument: Compothixo (Kerr).  The prepared sections were observed on a scanning electron microscope (SEM), VEGA II model LSH (TESCAN). RESULTS: When using Compothixo, the average working time was 8.53 min / restoration while, when using standard instruments, the average working time was 10.32 min, which seems to indicate that the vibration technique was more effective than traditional condensation. Microscopic images have shown that neither vibrating condensation nor manual condensation precluded the formation of a hiatus in some areas of the interface between the restoration and the cavity walls, especially in areas of small irregularities. CONCLUSIONS: Condensation of composite resins can be faster when using vibrating instruments. Adaptation of the material to the cavity walls is comparable to that obtained by traditional techniques