Spannungen innerhalb von Bruckenkonstruktionen bei nicht parallelen Ankerzahnen

Mosne konstrukcije, u okviru fiksno-protetske terapije, kao sredstvo za višestruku rehabilitaciju žvačnog organa, premošćuju i nadoknađuju bezube predjele čeljusti i prenose žvačni tlak neposredno preko zuba nosača na parodont i ostale potporne strukture, približavajući se tim e prirodnim uvjetima koji vladaju u ustima. Potpuna se paralelnost zubi nosača ne može postići u mnogim slučajevima, isključujući pritom ortodontski ili endodontski međuzahvat, no, usprkos tomu, mostovi se uspješno postavljaju i ako postoji disparalelnost nosača i do 30 stupnjeva. Opterećenost ovakvih konstrukcija je neravnomjerna i specifična u odnosu na konstrukcije s paralelnim nosačima.Autor je u ovom radu nastojao, na eksperimentalnim modelima, napravljenim za tu svrhu, pokazati mjesta najvećeg opterećenja mosne konstrukcije, pri koncentričnim silama, neparalelnih nosača. Kao metoda izbora, odabrana je fotoelasticimetrijska analiza, povoljna za prikazivanje unutrašnjih naprezanja, složenim geometrijskim strukturama, a pomoću vidljivih svjetlosnih fenomena, određeni položaj i veličina sile.In fixed prosthetic therapy bridges are used for a manifold rehabilitation of the masticatory organ, for connecting and substituting the areas without teeth and to transfer the masticatory pressure directly through the bearer tooth to parodont and other supporting structures. In this way almost natural conditions are attained in the oral cavity. In a number of cases it is impossible to obtain total parallelism of bearer teeth excluding orthodontic and endodontic treatments. Nevertheless bridges are successfully set if the parallelism of the bearers deviates even for 30 degrees. The loading of such constructions is unequal and specific as compared to constructions with parallel bearers. In this ipaper the points of the highest load of bridge constructions under the effect of concentric forces and nonparallel bearers are shown on the experimental models made for this purpose. The selection method applied was the photoelastic analysis suitable for the presentation of inner tensions in complex geometric structures. The position and size of the force were determined by means of visible light phenomena.Brückenkonstruktionen im Rahmen der fixen prothetischen Therapie als Mittel für die Rehabilitation des Kauorgans, ersetzen zahnlose Kieferabschnitte und leiten den Kaudruck auf das Parodont und die übrigen Stützgewebe. Eine vollständige Parallelität der Ankerzähne ist in vielen Fällen nicht möglich zu erreichen, es sei denn mit orthodontischen und endodontischen Eingriffen. Trotzdem lassen sich Brücken bei Disparallelität bis 30° ohne besondere Schwierigkeiten einsetzen. Die Belastung dieser Konstruktionen ist ungleichmassig und spezifisch im Vergleich m it Konstruktionen bei parallelen Ankerzähnen. Auf experimentellen Modellen gelang es dem Autor die Stellen der grössten Belastung bei konzentrischen Kräften und nicht parallelen Brückenträgern, darzustellen. Als Methode der Wahl wurde die fotoelastizimetrische Analyse angewendet, geeignet zur Darstellung der inneren Spannungen mittels komplizierter geometrischer Strukturen, während sichtbare Lichtfenomäne die Lage und Grösse der Kräfte bestimmen

The effect of cyclic loads on the dynamic strength of a filled premolar crown

Mehanizam nastanka početnih pukotina i lomova, koji uzrokuju djelomičan ili potpuni manjak krune čovjekova zuba, izvanredno je složen i ne­potpuno istražen, premda je liječenje ovih oštećenja dobro ponzato i u djelokrugu je svakodnevnog rada stomatologa. Mnogobrojna dosadašnja istraživanaj upućuju na zaključak o različitom pristupu ovom problemu, pri čemu su zanemarena istraživanja cikličkih opterećenja i dinamičke iz­držljivosti zubi. Autor je u radu istraživao djelovanje cikličkih opterećenja na brušenim pretkutnjacima za fasetiranu krunicu. Istraživanje je objavljeno na skupini od 32 zdrava zuba u modificiranom Amslerovom visokofrekventnom pulzatoru. Rezultatima istraživanja utvrđena je gornja granica dinamičke čvrsto­će pretkutnjaka od 1600 N. Dinamičko trajno opterećenje za ovu skupinu zubi iznosilo je 300 N. Dijagramom dinamičke izdržljivosti utvrđeni su brojevi potrebnih ciklusa za pojedine veličine opterećenja, u rasponu od 300 do 1600 Newtona, da dođe do loma zuba.The mechanism of the occurrence of fissures and splits causing a partial or complete lack of crown in human teeth is extremely complex and as yet inadequately studied, although the treatment of these lesions has been widely introduced in daily dental practice. Many studies con­ducted so far point to different approaches to the problem, but studies on cyclic loads and dynamic tooth strength have been neglected. In this study, the effect of cyclic loads on the facet crown of filled premolares was assessed in 32 healthy teeth using a modified Amsler\u27s high-frequency pulsator. The upper limit of the dynamic strength of pre­molars was found to be 1600 N, whereas permanent dynamic load for this group of teeth was 300 N. Using a dynamic strength diagram, the number of cycles for particular loads, ranging from 300 to 1600 Newtons, required for a fissure to occur was determined

[The possibility of the reconstouction of fractured crowns after endodontic treatment]

U današnjoj literaturi postoje različite podjele, tipovi i metode izrade i ugradnje elemenata za nadograđivanje fraikturiranih kliničkih kruna endodontski saniranih zuba. Cilj rada bio je (prikazati i sistematizirati različite načine nadogradnje zuba prema našoj podjeli nadogradnja, komentirati njihova svojstva i potvrditi prednost metode nadograđivanja zuba usvojene na Zavodu za fiksnu protetiku u Zagrebu. Nakon sistematizacije i opisa pojedinih metoda, zaključeno je da konfekcijske nadogradnje imaju ograničeno indikacijsko područje, zbog štandardiziranosti dimenzija, nedovoljno riješenog piatnja ekstraradikularnog dijela i financijskog faktora. Lijevane nadogradnje miaju široko indikacijsfko područje i bolju adaptacijsku sposobnost na morfološke oblike nadograđivanih zuba. Uspoređujući direktnu metodu modelacije u vosku i akrilatu, usvojenu na Zavodu, sa sličnim metodama opisanim u ovom radu, autor zaključuje da je ona brža i jednostavnija, a postiže se isti efekat.Recent publications present different classifications, types and methods for the preparation and reconstruction of new elements to fractured clinical crowns of endodotically cured teeth. The objective of this paper was to present and classify systematically various modes of such affixations, to comment on their advantages and disadvantages and to show the merits of the affixation method adopted by the Institute of Fixed Prosthodontics in Zagreb. After a presentation of the classification and of the description of several methods, it is concluded that ready-made elements for annexing crowns have a limited field of indication, because of their standard dimensions, insufficiently solved extraradicular portion and because of financial expenses. Cast elements have a wide field of indication and are more adaptable to the morphological shapes of the reconstructed teeth. By comparing the direct wax and acrylate modelling method, used at the author\u27s Institute, with some other similar methods presented in this pa\u27per, he concludes that it is faster, simpler and more efficient

Provisional Aesthetic Crowns on a Dowel/Post

Privremene krunice upotrebljavaju se kao sredstvo za zaštitu zuba ili zubi na kojima se provodi trajna protetska terapija, a funkcija im je višestruka: biološka, estetska i mehanička. U radu je prikazan slučaj pacijentice s nedovoljno ispunjenim korijenskim kanalom gornjega središnjeg sjekutića opskrbljenog nepravilno postavljenim i pogrješno indiciranim konfekcijskim kolčićem. Pošto je kolčić izvađen prikazana su tri načina izradbe estetske krunice na kolčić koja će poslužiti kao privremena krunica za vrijeme trajanja endodontske i trajne protetske terapije. Prikazani načini izradbe privremenoga rada s intraradikularnim sidrenjem moguće su smjernice u estetskom pristupu kombiniranoj endodontskoj i protetskoj terapiji prednjih zuba.Provisional crowns are used as a means of protection for a tooth or teeth on which permanent prosthetic therapy is performed. Their function is multiple: biological, aesthetic and mechanical. The paper presents the case of a female patient with insufficiently filled root canal of the upper middle incisor, and an incorrectly placed and erroneously indicated prefabricated dowel. After extraction of the dowel, three methods are presented for construction of an aesthetic crown on a dowel, serving as a provisional crown during endodontic and permanent prosthetic therapy. The presented methods for construction of provisional work with intraradicular anchorage represent possible guidelines for an aesthetic approach to combined endodontic and prosthetic therapy of frontal teeth

Investigation of the Correlation Between the State of Prosthodontic Appliances, Organ System Dysfunctions and the Degree of Independence in Elderly Home Residents

Svrha istraživanja bila je procijeniti kakvoću protetskih nadomjestaka u vezi s kroničnim bolestima organskih sustava i stupnjem pokretljivosti u skupini osoba starije dobi. Istraživanje je provedeno na skupini od 175 štićenika umirovljeničkih domova grada Zagreba starijih od 60 godina (prosječna starost 76,8 godina, S D 10,72), koju je činilo 66 muških (37%) i 109 ženskih (63%) osoba. Stomatološki pregled popraćen je općemedicinskom i stomatološkom anamnezom. Procjena kakvoće fiksnoprotetskih radova učinjena je prema sustavu Kalifornijske stomatološke udruge (CDA) (10), a proteza prema modificiranome Nevalainen i sur. indeksu. Za utvrđivanje stupnja pokretljivosti uporabljen je indeks za procjenu aktivnosti dnevnoga života prema Miuri, Arakiju i Umenaiju. U viπe od 82% ispitanika trebalo je izraditi nove fiksne, mobilne ili kombinirane protetske nadomjestke. Najčešći zdravstveni problemi uključivali su kardiovaskularni (29%) i lokomotorni sustav (18%). Utvrđena je povezanost između lošega stanja protetskih nadomjestaka i kroničnih bolesti lokomotornoga sustava (r=0,69, p<0,05), kardiovaskularnoga sustava (r=0,54, p<0,05), duševnih bolesti (r=0,88, p<0,05), neuroloških poremećaja (r=0,72, p<0,05), i bolesti probavnoga sustava (r=0,65, p<0,05). Spearmanova raščlamba korelacije utvrdila je znatnu povezanost između procijenjene ADL vrijednosti i vrijednosti CDA indeksa (ρ= -0,468, p<0,01) s jedne strane, te vrijednosti modificiranog Nevalainenova indeksa (ρ=-0,572, p<0,01). Niža ADL vrijednost bila je povezana s lošijim stanjem protetskih nadomjestaka.The aim of the investigation was to evaluate the quality of prosthodontic appliances relative to chronic organ system dysfunctions and the level of independency in a group of elderly individuals. The study group included 175 elderly home residents in the Zagreb region over 60 years of age (average 76.8 years, S.D. 10.72), which consisted of 66 male (37%) and 109 female (63%) individuals. The examination included dental status, oral and general health history. Quality of prosthodontic appliances was evaluated according to the CDA index for fixed, and the modified Nevalainen et al. index for removable prosthodontic appliances. Assessment of functional independency of an individual was done using the Activity of Daily Living index by Miura, Araki and Umenai. Over 82% of individuals were in need of fixed, removable or combined prosthodontic treatment. The most common general health conditions involved cardiovascular (29%) and locomotor (18%) systems. Correlation was determined between the poor state of prosthodontic appliances and chronic conditions of CVS (r=0.54, p<0.05) and locomotor (r=0.69, p<0.05) systems, psychological (r=0.88, p<0.05), neurological (r=0.72, p<0.05) and digestive (r=0.65, p<0.05) dysfunctions. Spearman\u27s correlation analysis determined significant correlation between the ADL and the CDA indices scores (r=-0.468, p<0.01), and the ADL and the modified Nevalainen\u27s et al. indices scores (r=-0.572, p<0.05), where lower ADL scores were correlated to the poorer condition of the prosthodontic appliances

Comparative Investigation of the Fracture Strengths of Crowns of Three Different Non-metal Materials

Zahtjevi pacijenata za visokom estetikom tijekom rekonstruktivnih protetskih zahvata pospješili su razvoj novih materijala i tehnologija. Sile koje djeluju u postkaninom dijelu zubnoga niza iznose ≥ 500 N, pa i materijali koji se upotrebljavaju za izradbu nadomjestaka moraju izdržavati te sile. Svrha je istraživanja bila istražiti otpornost na lom triju nekovinskih materijala: 1. ceromer (Targis, Ivoclar-Vivadent), 2. ceromer ojačan vlaknasto ojačanim kompozitom (Targis/Vectris, Ivoclar-Vivadent), 3. nekovinski keramički sustav (IPS Empress 2, Ivoclar-Vivadent). Iz svake vrste materijala izrađeno je po 18 istovjetnih krunica na gipsanome modelu izbrušenog prirodnog drugoga donjeg pretkutnjaka, prema uputama proizvođača. Isti je brušeni zub upotrijebljen za izradbu kovinskoga modela na kojemu su umetane krunice u univerzalnu kidalicu ZWICK. Tlačna je ploča modificirana s trnom dijametra 7 mm koji je djelovao silom na okluzijsku plohu pod kutom od 180°. Sila je aplicirana do prvoga znaka loma, a iznos je zabilježen. Polovina je uzoraka prije ispitivanja termociklirana 1000 puta po 20 sekunda na temperaturi od 2°C i 55°C s razmakom od 40 sekunda između urona za temperiranje uzoraka. Izmjerena srednja vrijednost iznosa sile do loma za netermociklirane uzorke iznosile su za krunice iz ceromera 577,8 ± 113,4 N, za krunice iz ceromera i vlaknasto ojačanoga kompozita 923,3 ± 229 N, a za krunice iz nekovinske keramike 1208,9 ± 161,8 N. Mann-Whitney U testom utvrđena je znatna razlika između svih triju materijala (p<0,05) u iznosima opterećenja do loma uzorka. Termocikliranje nije znatno smanjilo iznos sile do loma uzorka. Istraživanjem je utvrđeno da su sva tri materijala pogodna za izradbu trajnih nadomjestaka u području žvačnoga središta, jer svi mogu izdržati silu veću od 500 N.The demands of patients for high aesthetics during reconstructive prosthetic procedures accelerated the development of new materials and technology. Forces acting in the post-canine part of the dental arch amount to ≥ 500 N, and thus the material used for fabrication of the restoration must withstand such forces. The aim of this investigation was to study the resistance to fracture of three non-metal materials: 1. ceromer (Targis, Ivoclar-Vivadent), 2. ceromer reinforced with fibre reinforced composite (Targis/Vectris, Ivoclar-Vivadent), and 3. non-metal ceramic system (IPS Empress 2, Ivoclar-Vivadent). Eighteen identical crowns were fabricated from each type of material on a plaster model of a polished natural second lower premolar, according to the manufacturer’s instructions. The same tooth was used for fabrication of a metal model on which crowns were placed in the universal testing device ZWICK. The compressive plate was modified with a pin 7mm in diameter, which acted with force on the occlusal surface at an angle of 180˚. Force was applied up to the first sign of fracture, and the amount recorded. Half of the samples prior to the examination were thermocycled 1000x for 20 seconds at temperatures of 2˚C and 55˚C with 40 second intervals between immersion of the tempered sample. The mean value measured of the amount of force up to fracture for non-thermocycled samples amounted to 577.8 +/- 113.4 N for crowns of ceromer, 923.3+/- 229 N for crowns of ceromer and fibre reinforced composite, and 1208.9 +/- 161.8 N. for crowns of non-metal ceramic. Significant difference was determined by Mann-Whitney U test between all three materials (p < 0.05) for the amounts of loading up to fracture of the samples. Thermocycling did not significantly reduce the amount of force up to fracture of the sample. The investigation determined that all three materials are satisfactory for fabrication of permanent restorations in the area of the masticatory centre, as all withstand force greater than 500 N

Epidemiological Study on Removable Denture Deliveries in Different Districts of Croatia, 1996–2001 and 2002

Aim of this study was to determine the prevalence of removable denture (complete and partial) deliveries through Croatian Public Health Service (covered by insurance) in different districts of Croatia and to compare the two periods: 1996 to 2001 and 2002. Number of dentures delivered was obtained from Croatian Institute for Health Insurance for the district of Zagreb, Rijeka, Split and Karlovac. Information of the population living in the same districts was obtained from the National Institute for Statistics. The percentage of fully edentulous inhabitants varied from more than 13% to more than 20%, dependent on the district, while the percentage of partial edentulism reconstructed with removable partial dentures varied from more than 13% to more than 30%. The highest percentage (average for living population) of complete and removable partial dentures was delivered in Zagreb in the both observed periods. In all districts, the number of complete denture wearers increased in 2002, except in Split. The percentage of removable partial denture deliveries increased significantly in all examined districts. Partial and complete denture deliveries increased in higher percentage in population younger than 70 years than in older population. The percentage of metal framework removable partial dentures increased significantly in all districts. The prevalence of removable denture deliveries increased, especially in patients younger than 70 years. This was attributed not only to the consequences of the 1991–1995 war, the migrations from rural to urban areas, decrease of economic status, but also to the new rules of the Croatian Insurance System

[Analysis of metal consumption in the manufacture of cast superstructures]

U svakodnevnoj stomatološkoj praksi često se liječeni zubi oštećenih kliničkih kruna uključuju u fiksnoprotetski izdjeljak, kojemu potporu uz preostali dio očuvane kliničke krune čini «lijevana nadogradnja. Svrha rada bila je istražiti relativnu količinu utroška paladiij-srebrne slitine pri izradi ovog tipa nadogradnje s obzirom na vnstu zuba i spol. Pomoću izraza za masu poznatog volumena odredile su se i usporedile količine utroška poludragocjene (paladij-srebrne) i dragocjenih (20 kt. zlatne i 18 + 8 platinsko-zlatne) slitina za jednake volumene nadogradnji. Istraživanje je provedeno na 900 nadograđivanih zuba u objema čeljustima pacijenata svih životnih dobi. Modelacija nadogradnji načinjena je voskom i akrilatom direktnom metodom u ustima pacijenta, a mjerenje težine odljeva preciznom vagom. Dobiveni rezultati pokazali su da prosječna težina odljeva nadogradnji iz paladij-srebrne slitine varira između 0,77 gr. na donjim sjekutićima do 2,66 gr. na gornjim kutnjacima. Nadogradnje u muških ispitanika bile su prosječno teže od ženskih za istu vrstu zuba 0,10— 0,20 grama. Matematičkom analizom ustanovljeno je da za jednake volumene nadogradnji, treba utrošiti 60% veću količinu dragocjenih od poludragocjenih slitina.In the stomatological routine, treated teeth of the damaged clinical crowns are frequently inserted into a fixed prosthetic appliances, supported by both a cast superstructure and the remaining part of the clinical crown preserved.The aim of this work was to study the relative amount of the palladium-silver alloy consumed during the construction of this type of appliance, in relation to age and type of teeth. The amounts of a isernnprecious (palladium-silver) and precious (20 ct gold and 18 + 8 platinum-gold) alloys consumed during manufacture of identical volumes of appliances were assessed and compared using the expression for known volume mass. The study was carried out in 900 teeth with superstructures in both jaws of patients of all age groups. Casting of the superstructure was made by means of wax and acrylate using the direct method, i.e. im the patient’s mouth, whereas the cast weigh was determined using a precise balance. The results obtained have shown the mean weight of superstructures cast from the palladium-silver alloy to range from 0,77 g on lower incisors to 2,66 g on upper molars. In males, the supersturctures weighed 0,10— 0,20 g more than in females for the same teeth. Mathematical analysis has revealed that a 60% higher amount of precious alloys compared to semi-precious ones has to be consumed for the same volumes of superstructures