The applicability of Resonance Frequency Analysis (RFA) in evaluation implant stability

The most important prerequisite for successful osseointegration is achievement and maintenance of implant stability. Recent clinical findings have demonstrated that only implants with high primary stability can be subjected to immediate loading protocol with predictable result. The purpose of this in vivo study was: (1) to determine the changes in implant stability after 6 months of functional loading by using RFA; (2) to evaluate implant stability of 4 implant systems utilizing different techniques for preparing surface roughness; and (3) to compare the results of RFA measurements with histomorphometrical data. 2 mongrel dogs were edentulated bilaterally in the mandibular and maxillary premolar areas. After 3 months, implants were placed in a pattern, 4 different implants per quadrant (n=32): (1) Mk III (RP), TiUnite, Nobel Biocare, Sweden D-3.75, L-10; (2) ITI-Screw, ITI TPS, Straumann, Switzerland D-4.1, L-10; (3) 3I-Osseotite, Implant Innovation, USA D-3.75, L-10; and (4) XiVE, Cell-Plus, Friadent, Germany D-3.4, L-11. Implants were subjected to immediate loading with 4 unit gold cast bridges (3-5days post implantation). Resonance Frequency Analysis - RFA, (Osstelltm, Integration Diagnostics, Sävedalen, Sweden) was used for measurement of implant stability after insertion, as ISQ surgical, and 6 months later, as ISQ prosthetic. Histomorphometrical evaluation - BIC%, the percentage of implant to bone contacts were quantified in the defined zone of interest (total peri-implant area) by computer assisted histomorphometry. In this experimental setting, all evaluated surfaces achieved a good bone-to-implant contact and implant stability. The study demonstrated no statistically significant difference in implant stability and amount of bone-to-implant contact between implant systems utilizing different techniques for preparing surface roughness. Decrease or increase of ISQ values were not always correspondent to histomorphometrical data

Fracture toughness of zirconia ceramic crowns made by feather-edge tooth preparation design

Background/Aim. Fracture toughness determines functional crown strenght and prevents damages on ceramics during mastication. There is a lack of relevant literature data about fracture toughness of crowns made by feather-edge preparation. Mechanical testing of ceramic samples is supposed to show if feather-edge tooth preparation is a successful method for making ceramic crowns without any risk of reduction of their mechanical properties. This research was done to establish effects of feather-edge tooth preparation on fracture toughness of single zirconia ceramic crowns. Methods. The research was performed as an experimental study. Sixty (60) ceramic crowns were made on non-carious extracted human premolars. Thirty (30) crowns were made on the basis of feather-edge preparation (experimental group I). The group II included 30 crowns made on 1 mm rounded shoulder. Crowns fabrication was executed on a copy mill production system “Zirkonzahn” (Zirkonzahn GMBH, Gais, Germany). The spherical compression test was used to determine fracture toughness, using 6 mm diameter ceramic ball. Fracture load for damaging ceramic crown was recorded on a universal testing machine - Zwick, type 1464, with the speed of 0.05 mm/min. Results. The results of this research introduced significant differences between fracture toughness of ceramic samples in every examined group. However, fracture toughness of crowns from both group was above 2 000 N, what was double beyond a recommended value. The mean value of fracture toughness in the feather-edge group was 2 090 N, and in shoulder group it was 2 214 N. Conclusion. This research showed a high fracture toughness of zirconia crowns made on feather-edge preparation. The examined crowns showed a fracture resistance at a sufficient distance in relation to the minimum values of functional loads. Further research of functional loads of these crown is necessary, as well as research of marginal adaptation of cemented crowns and gingival inflammatory response

Therapeutic efficacy of connective tissue autotransplants with periosteum and platelet rich plasma in the management of gingival recession

Background/Aim. Gingival recession progression in clinical practaice has influenced the development of various surgical procedures and techniques for solving esthetic imperfections and subjective difficulties coused by gingival recession. The aim of this study was to verify efficacy of surgical procedures and to compare both of surgical procedures through the keratinized tissue width. Methods. The study included 20 teeth with gingival recesion, Müller class I and II. Ten teeth with gingival recession were treated with connective tissue autotransplants with periosteum in combination with coronary guided surgical flap (CTG group). On the contralateral side 10 teeth with gingival recession were treated with the same surgical procedures but in combination with platelet-rich plasma (CTGPRP group). We measured the keratinized tissue width. For statistical significance we used the Student's t-test. Results. The study reveled a statistical significance in reducing vertical deepress of recession by both used treatments. Root deepness in CTG and CTG-PRP group was 90% and 93.5%, respectively. With both surgical techniques we achieved larger zone of keratinized gingiva but with a wide zone of keratinized tissue in CTG - the PRP group. Conclusion. The concept regeneration technique with PRP and with the stimulating influence of platele activated growth factors results in the regeneration of deep periodontal tissue as an important prerequisite for the successful treatment of gingival recession

Pouzdanost primene konvencionalnih ključeva za određivanje boje zuba

Background/Aim. Color matching in prosthodontic therapy is a very important task because it influences the esthetic value of dental restorations. Visual shade matching represents the most frequently applied method in clinical practice. Instrumental measurements provide objective and quantified data in color assessment of natural teeth and restorations. In instrumental shade analysis, the goal is to achieve the smallest ΔE value possible, indicating the most accurate shade match. The aim of this study was to evaluate the reliability of commercially available ceramic shade guides. Methods. VITA Easyshade spectrophotometer (VITA, Germany) was used for instrumental color determination. Utilizing this device, color samples of ten VITA Classical and ten VITA 3D - Master shade guides were analyzed. Each color sample from all shade guides was measured three times and the basic parameters of color quality were examined: ΔL, ΔC, ΔH, ΔE, ΔElc. Based on these parameters spectrophotometer marks the shade matching as good, fair or adjust. Results. After performing 1,248 measurements of ceramic color samples, frequency of evaluations adjust, fair and good were statistically significantly different between VITA Classical and VITA 3D Master shade guides (p = 0.002). There were 27.1% cases scored as adjust, 66.3% as fair and 6.7% as good. In VITA 3D - Master shade guides 30.9% cases were evaluated as adjust, 66.4% as fair and 2.7% cases as good. Conclusion. Color samples from different shade guides, produced by the same manufacturer, show variability in basic color parameters, which once again proves the lack of precision and nonuniformity of the conventional method.Uvod/Cilj. Određivanje boje zuba u protetskoj terapiji predstavlja veoma važan zadatak jer utiče na prirodan izgled i estetsku vrednost zubnih nadoknada. Vizuelni metod određivanja boje zuba najčešće se koristi u kliničkoj praksi. Instrumentalna merenja pružaju objektivne i kvantifikovane podatke u proceni boje prirodnih zuba i restauracija. U instrumentalnoj analizi boje cilj je da se postigne najmanja moguća vrednost ΔE, što predstavlja najtačniji izbor nijanse. Cilj ovog istraživanja bio je da se utvrdi pouzdanost najčešće korišćenih ključeva za određivanje boje zuba. Metode. Za instrumentalni izbor boje korišćen je VITA Easyshade spektrofotometar (VITA, Germany). Uz pomoć ovog uređaja, analizirani su uzorci boja 10 VITA Classical i 10 VITA 3D - Master ključeva boja. Svaki uzorak boje analiziran je tri puta i ispitivani su osnovni parametri kvaliteta boje: ΔL, ΔC, ΔH, ΔE, ΔElc. Stepen poklapanje boje nadoknade sa ciljnom nijansom spektrofotometar izražava kroz tri ocene kvaliteta: good, fair i adjust. Rezultati. Nakon izvršenih 1 248 merenja keramičkih uzoraka boje, frekvencije ocena adjust, fair i good statistički su se značajno razlikovale između VITA Classical i VITA 3D - Master ključeva boja (p = 0.002). U VITA Classical ključu boja bilo je 27,1% ocene adjust, 66,3% fair i 6,7% ocene good. U VITA 3D - Master ključu boja bilo je 30,9% ocene adjust, 66,4% fair i 2,7% ocene good. Zaključak. Uzorci boje iz različitih ključeva boja proizvedenih od istog proizvođača, pokazuju varijabilnost u osnovnim parametrima boje, što ukazuje na nepreciznost i neuniformnost konvencionalne metode

Imedijatno opterećenje implantata fiksnim zubnim nadoknadama - studija na psima

Background/Aim. Immediate loading is considered to be the most innovative technique in contemporary implant dentistry. Recent clinical and experimental findings have demonstrated that only implants with high primary stability can be subjected to immediate loading protocol with predictable results. It is generally accepted that the most important prerequsite for successful osseointegration is achievement and maintenance of implant stability. The aim of this in vivo study was to investigate the possibility for successful application of immediate loading protocol in implant systems with different surface properties. Methods. In the experimental study 2 mongrel dogs were edentulated bilaterally in the mandibular and maxillary premolar areas. After 3 months implants were placed in a pattern 4 different commercially available implants per quadrant (n = 32): Mk III TiUnite (Nobel Biocare, Sweden), ITI TPS (Straumann, Switzerland), 3IOsseotite (Implant Innovation, USA) and XiVE Cell-Plus (Friadent, Germany). Implants were subjected to immediate loading with 4 unit gold cast bridges, 2 days post implantation. The assessment of implant stability and immediate loading possibilities were done by performing Resonance frequency analysis (RFA). Results. After a 6- month loading period all bridges were in function and all implants occurred well osseointegrated. When summarizing the Implant Stability Quotient (ISQ) values, it was noted that resonance frequency was significantly higher for mandibular implants. The results of this experimental setting showed that all evaluated surfaces achieved good implant stability. Increase of ISQ values was found for all implants in the mandible and partially decrease of ISQ values for maxillary implants after 6 months of functional loading with 4 unit bridges. Conclusions. Investigated endooseal implants did not show different degree of osseointegration, because there was not statistically significant difference among observed parameters (ISQh i ISQp) between implant systems.Uvod/Cilj. Imedijatno opterećenje implantata smatra se jednim od najznačajnijih dostignuća savremene dentalne implantologije. Rezultati novijih kliničkih i eksperimentalnih studija pokazali su da samo implantati visoke primarne stabilnosti mogu biti izloženi protokolu imedijatnog opterećenja zubnom nadoknadom sa predvidivim ishodom. Cilj studije bio je da se ispita mogućnost uspešne primene protokola imedijatnog opterećenja implantata različitog mikrodizajna fiksnim zubnim nadoknadama. Metode. U eksperimentalno istraživanje uključena su dva psa, obezubljena obostrano u premolarnoj regiji gornje i donje vilice. Nakon tri meseca od ekstrakcije zuba, ugrađena su, po predviđenoj šemi, četiri različita implantata po kvadrantu (n = 32): Mk III TiUnite (Nobel Biocare, Sweden), ITI TPS (Straumann, Switzerland), 3I-Osseotite (Implant Innovation, USA) i XiVE Cell-Plus (Friadent, Germany). Implantati su imedijatno opterećeni fiksnim zubnim nadoknadama, četvoročlanim mostovima od plemenite legure zlato-platina, dva dana posle implantacije. Stabilnost implantata i mogućnost imedijatnog opterećenja ocenjivana je na osnovu analize rezonantnih frekvencija (RFA). Rezultati. Šest meseci nakon implantacije i imedijatnog opterećenja fiksnom zubnom nadoknadom, svi mostovi bili su u funkciji i svi implantati uspešno integrisani, ne pokazujući znake mobilnosti. Sumiranjem dobijenih vrednosti koeficijenta stabilnosti implantata (ISQ) ustanovljeno je da su rezonantne frekvencije bile značajno veće kod implantata u donjoj vilici. Rezultati eksperimentalnog istraživanja pokazali su da su sve analizirane površine ostvarile dobru implantatnu stabilnost. Utvrđen je porast ISQ vrednosti kod svih implantata u mandibuli i delimičan pad ISQ vrednosti za implantate u maksili, nakon šest meseci funkcionalnog opterećenja fiksnim zubnim nadoknadama. Zaključak. Ispitivani endoosealni implantati nisu pokazali različit stepen oseointegracije jer se rezultati merenih parametara hirurških (ISQh) i protetkih (ISQp), nisu statistički značajno razlikovali između implantatnih sistema

Biofilm Adhesion and Micromorphology Analysis after Professional Oral Hygiene Procedures on CAD/CAM Milled and Veneered Zirconia Restorations: In Vitro Study

Objective: The purpose of this study was to evaluate the surface texture and biofilm adhesion of veneered or CAD/CAM milled zirconia (partially stabilized with yttrium) after professional oral hygiene procedures. The samples (4 × 4 mm, thickness 2 mm; n  =  72) were separated from zirconia blanks (3Y-TZP-LA). One group was veenered with ceramics, and the other group of samples was CAD/CAM milled. Each group had two subgroups: polished and glazed. The samples were subjected to simulated strokes of professional brushing using abrasive paste and ultrasonic scaling. The parameters of surface micromorphology and receptivity to biofilm were calculated before and after simulating the given methods of the professional maintenance of oral hygiene. Scanning electron microscopy (SEM) was used to evaluate zirconia surface properties. Microbial (bacterial/fungal) species (Staphylococcus aureus, Streptococcus sanguinis and Candida albicans) were used and cultured on respective sterilized zirconia surfaces. Colony-forming unit (CFU) counts were used to quantify the amount of biofilm formation on zirconia samples surfaces. Results: The SEM analysis showed the greatest change in surface microtopography after the use of ultrasonic scaling on glazed zirconia samples. Less formation of colonies on the surfaces of CAD/CAM milled zirconia restorations was observed. Conclusion: Routine methods of oral hygiene professional maintenance can damage the surfaces of glazed zirconia restorations

Kombinovana metoda izrade privremenih mostova

Perfect temporary care guarantees us the complete trust of our patients. From a chemical standpoint Luxatemp or Acrytemp can be classified as bis-acrylic materials. This class of materials has numerous advantages that give us many possibilities for successful clinical use: compatibility with the pulp, lowest setting temperatures, good flexural strength, low shrinkage and high abrasion resistance. The purpose of this paper is to present method of fabrication fixed provisional restorations using a vacuum formed tray matrix with new generation of temporary materials.Adekvatno izrađene privremene nadoknade nam obezbeđuju između ostalog i sticanje pacijentovog poverenja. Luxatemp ili Acrytemp pripadaju grupi bis-akrilatnih kompozita. Ovi materijali imaju brojne prednosti: kompatibilnost sa pulpo-dentinskim kompleksom, nisku temperaturu polimerizacije, dobru otpornost na savijanje, malu kontrakciju i dobru otpornost na abraziju. Cilj ovog rada je bio da prikaže kombinovanu metodu izrade privremenih mostova upotrebom transparentnih plastičnih kalupa u kombinaciji sa novom generacijom materijala za izradu privremenih nadoknada

Mehanske lastnosti materialov za nočne zobne ščitnike

The aim of this study is to investigate the mechanical properties of polymethyl methacrylate (PMMA) and thermoplastic polycarbonate (TPC) materials in order to produce night bruxoguards. For this purpose we used a static tensile test. In the next step the microstructures of PMMA and TPC were observed. Within this framework special attention was paid to the examination of the tensile-test tube fracture surfaces for both materials. This approach revealed that PMMA is a brittle and TPC is a plastic material. Certain mechanical properties and a review of the crucial areas confirmed that the TPC material is extremely favourable for making occlusal splints.Namen te študije je preiskava mehanskih lastnosti polimetil metakrilata (PMMA) in termoplastičnega polikarbonata (TPC) za izdelavo nočnih zobnih ščitnikov. Za ta namen je bil uporabljen statični natezni preizkus. V naslednjem koraku je bila preiskana mikrostruktura PMMA in TPC. Posebna pozornost je bila namenjena preiskavi površine preloma na ceveh za natezni preizkus, izdelanih iz obeh materialov. Tako je bilo ugotovljeno, da je PMMA krhek material, TPC pa plastičen. Nekatere mehanske lastnosti in pregled ključnih področij potrjujejo, da je za izdelavo okluzalne opornice izredno primeren material TPC