Examining Vibrations in Dental Procedures

Dugogodišnjim radom mogu se zbog djelovanja vibracija i u stomatologa i u zubnih tenhičara pojaviti određene zdravstvene poteškoće. Svrha rada bila je izmjeriti i usporediti neke parametare u vezi s vibracijama koje utječu na zdravlje stomatologa i zubnih tehničara i to vibracija koje proizvode tehnicki mikromotori sa svrdlima različitih oblika i materijala pri različitim brojevima okretaja. Vibracije su mjerene akcelerometrom postavljenim na tehničkom mikromotoru te na određenim dijelovima tijela ispitanika, uređajem koji se sastoji od piezosenzora, pojačala, filtara i prijenosnog uređaja za snimanje. Dobiveni signali analizirani su računalnim programom SpectraLAB i uspoređeni sa sadašnjim međunarodnim standardima. Statistička raščlamba podataka izvedena je s pomoću programskih paketa: STATISTICA for Windows, Release 5.5 H i SPSS for Windows. Temeljni čimbenik koji utječe na vibraciju jest broj okretaja kojim se služimo tijekom obradbe protetskoga rada. Dobiveni rezultati pokazuju da su vrijednosti ubrzanja vibracija unutar vrijedećih standarda, premda su vrijednosti vibracija radom na 40000 okretaja/min. vrlo blizu gornjoj granici tih standarda. Spektrografska raščlamba vibracija pokazala je da broj okretaja određuje na kojim će frekvencijama biti izražene vršne vrijednosti. Budući da postoje dokazane vibracijske bolesti stomatologa i zubnih tehničara preporučuje se upozoravati osobe koje rukuju takvim alatima na moguće posljedice, a dobiveni rezultati mogu biti korisni da bi se prevenirale takve bolesti i upotrebljavale brzine okretaja koje proizvode najmanje vibracija.Certain health problems may appear both in dentists and dental technicians due to long periods of exposure to vibrations. The aim of the study was to measure and compare some factors related to vibrations which affect the health of dentists and dental techicians, particularly those produced by mocromotors with drills of different shapes, made of different materials rotating at different speeds. Vibrations were measured by an accelerometre which was placed an the technical micromotor and on various body parts of subjects. The device consists of a piezosensor, an amplifier, a filter and mobile recording device. The obtained signals were analysed by the SpectraLAB computer programme and consequently compared with presently valid international standards. Statistical data analysis was carried out by PC software, STATISTICA for Windows, Release 5.5 H and SPSS for Windows, Release 7.5. The main factor that effects vibration is the rotation number used in the course of prosthetic replacement processing. The obtained results point to the fact that the vibration acceleration values are within accepted standards, although the vibration values at 40000 rotations per minute approach the maximum limit of these standards. The spactral analysis of vibration revealed that the rotation number determined the frequencies of the maximum values. Since there is strong evidence to support vibration related illnes in dentists and dental technicians, it is recommended that individuals who use such devices be warned about the possible harmful effects. The obtained results may be used in prevention of such illness. They are also recommended to use rotation speeds which produce the least vibrations

ZrO2 Ceramic as an Esthetic Post

Uspješna endodontska terapija omogućuje da se spase jako oštećeni zubi. Manjak retencijske površine zuba najčešće se nadograđuje metalnim, konfekcijskim ili individualnim nadogradnjama. Problem je te restauracije sivoplava obojenost zubnih struktura. Zato nemetalni kolčići i nadogradnje imaju prednost kao retencijska podloga potpuno keramičkim krunicama, osobito kada se radi o prednjim prelomljenim ili obojenim devitaliziranim zubima. Osim staklo keramike sve češću uporabu kao biomaterijal u stomatološkoj protetici ima cirkonij-keramika zbog dobrih estetskih, kemijskih i mehaničkih svojstava te zbog dimenzijske stabilnosti. U radu će biti prikazan slučaj protetske sanacije prednjeg zbog traume prelomljenog zuba. Zub je endodontski obrađen. Temeljem rtg snimke normiranim je čeličnim i dijamantnim svrdlima odstranjena i izbrušena gutaperka do željene duljine korijenskoga kanala. Odabran je kolčić cirkonijevoga oksida (Biopost, Alfred Bech GmbH, Offenburg, Njemačka) prikladne duljine. Kolčić je nahrapavljen i pjeskaren sa zrncima Al2O3, veličine 150µm te adhezivno cementiran. Preostali dio kliničke krune nadomješten je kompozitom. U gingivni sulkus stavljen je retrakcijski končić. Temeljem dvofaznoga otiska izrađena je potpuna keramička krunica (Empress 2, Ivoclar, Schaan). Krunica je konačno pričvršćena adehzivnim cementom. Provedenom terapijom postignut je optimalan estetski i funkcijski učinak. Sve faze slikovno su prikazane.Successful endodontic therapy allows patients to retain severely damaged teeth. A minor retention surface is usually restored with metallic, commercial or individual posts. Silver-gray color posts is an esthetic problem in reconstruction of antetior teeth. Nonmetallic posts in combination with all-ceramic crowns are esthetically preferable for the restoration of endodontically treated anterior teeth with fractured or discolored coronal aspects. Glass ceramics as well as zirconimum oxide ceramik have been used as biomaterials in prosthodontics. Zirconium has good esthetic, chemical and mechanic properties and is dimensionally stable. In this study, a clinical case with prosthetic restoration of an upper fractured incisor has been discribed. After endodontic and radiograph treatment , the root canal was prepared with specific cylindrical steel and diamond burns. Gutta-percha was removed to the optimal depth of the root canal. Zirconium oxide post (Biopost, Alfred Becht GmbH, Offenburg, Germany) was chosen of suitable lenght. After roughening and sandblasting the surface of the ZrO2 post with particles Al2O3, size 150 µm, the post was adhesively cemented. The clinical crown was built with composite. Retraction thread was placed in gingival slucus. Monophase impression was taken. An all-ceramic crown, Empress 2 (Ivoclar, Schaan, Lichtenstein) was made. The ceramic crown was fixed with adhesive cement. Good esthetic and functional effect was achieved. All phases of the therapy have been illustrated by figures

METALLIC MATERIALS FOR USE IN DENTISTRY

Dentistry as a branch of medicine has an important role in the health of the human, while applying new technologies the maintaining of oral health is much more effective. For that purpose many dental products are used, such as crowns, bridges, implants, which are made of various metallic materials the mostly by casting or forging. They have to possess an adequate properties among which a biocompatibility, hardness and strength are the most important. Metal as an individual element with its properties does not meet certain conditions, therefore, the process of alloying results in different alloys that may be applied in oral environment. The most common classification of metallic materials for use in dentistry divides them in: noble and non-noble alloys and dental amalgames. Further, development of new technologies provides a new metallic materials with more adequate properties. Among them, titanium and titanium-based alloys stand out as materials of future in dentistry. Also, progress in computer technology results in faster production of economic dental products of much more quality

Zirconium Oxide Ceramics in Prosthodontics

Keramički materijali opravdavaju sve češću uporabu u restauraciji oštećenoga žvačnog sustava. »isti keramički sustavi rabe se u izradbi inleja, krunica i mostova manjih raspona. Cirkonijev dioksid je poznat polimorf. Dodatkom magnezijeva ili itrijeva oksida u određenom postotku, ZrO2 je potpuno ili djelomično stabiliziran i time je omogućena njegova uporaba u stomatološkoj protetici. Tetragonski cirkonski polikristal (TZP) stabiliziran s 3mol% itrija ima izvanredna mehanička i estetska svojstva i ima sve veću uporabu u restauraciji endodontski saniranih zuba, izradbi krunica i mostova CAD/CAM sustavom. Očekivati je da će taj keramički materijal nadomjestiti kovinsko-keramičke nadomjestke i u sanaciji gubitka većega broja zuba.Dental ceramics justifies more frequent use in prosthetic restoration of damaged dental status. Inlays, crowns and three-unit bridges have been made of all-ceramic system. Zirconia dioxide is a well- known polymorph. The addition of stabilising oxides like MgO, Y2O3 to pure zirconia, makes it completely or partially stabilized zirconia which enables use in prosthodontics. Tetragonal Zirconia Polycrystals (TZP) stabilized with 3mol % yttria, has excellent mechanical and esthetical properties. Fixed prosthetic appliances of this ceramic have been made using CAD/CAM techniques. It can be expected that zirconium oxide ceramics will replace metal-ceramics in restorations that require high strength

The effect of waste dental metallic materials on environment

Dental medicine is a profession dedicated to promoting and enhancing oral health and well- being and therefore plays a significant role in human health. Dental practices produce many types of dental wastes, such as: heavy metals and biomedical waste, which could cause harm to the environment if it is disposed improperly. Among them, mercury, silver and lead are the most harmful for humans and the environment as well. In order to reduce the impact on the environment dentists should take all possible activities to completely avoid the production of any waste or at least try to reduce the amount of waste to a minimum. In that context, eco- friendly dentistry as a new approach to dental practice is developed. It is based on use of non-toxic products, waste reduction, energy conservation and pollution prevention. Finally, education regarding the proper management and disposal of waste from dental offices needs more attention

Influence of the Partial Denture on the Articulation of Dental and Postalveolar Sounds

Dental prosthesis is a foreign body in oral cavity and thus necessarily interferes with speech articulation. The purpose of this study was to examine influence of partial denture on speech quality and to show eventual differences in pronunciation of dental sounds c, z, s and postalveolar sounds č, ž and š. We have examined differences in pronunciation between subjects with removable partial dentures, the same group without partial dentures and a control group. The study was performed on 30 subjects with removable partial dentures and 30 subjects with complete dental arch. All subjects were recorded while reading six Croatian words containing the examined sounds. Recordings were analyzed with Multispeech Program (Kay Elemetrics Inc.). Acoustic analysis – LPC (linear prediction coding) provided formant peaks (Hz) for each examined sound, its intensity (dB) and formant bandwidths (Hz). Results showed that subjects with partial dentures had 50% less distorted variables and that prostheses did not completely restore articulation of postalveolar sounds. Groups with and without prostheses had lower formant peaks intensities and wider formant bandwidths in comparison to the control group. Partial dentures have not significantly interfered with resonance frequency. At the same time, pronunciation of the examined sounds was significantly improved. However, precision of the articulation movements has deteriorated

The effect of waste dental metallic materials on environment

Dental medicine is a profession dedicated to promoting and enhancing oral health and well- being and therefore plays a significant role in human health. Dental practices produce many types of dental wastes, such as: heavy metals and biomedical waste, which could cause harm to the environment if it is disposed improperly. Among them, mercury, silver and lead are the most harmful for humans and the environment as well. In order to reduce the impact on the environment dentists should take all possible activities to completely avoid the production of any waste or at least try to reduce the amount of waste to a minimum. In that context, eco- friendly dentistry as a new approach to dental practice is developed. It is based on use of non-toxic products, waste reduction, energy conservation and pollution prevention. Finally, education regarding the proper management and disposal of waste from dental offices needs more attention

Chemical Durability of Dental Ceramic Material in Acid Medium

Stomatološki materijali moraju se ispitati prema strogim kriterijima kako bi se odredila njihova dugotrajna terapijska vrijednost. Kemijska degradacija dentalne keramike povećava njezinu hrapavost i istodobno trošenje antagonističkog zuba ili restorativnog materijala, povećava prianjanje plaka na keramiku, oslabljuje strukturu keramike uzrokujući kritičnu izmjenu iona na njezinoj površini i povećava osjetljivost keramike na buduće kemijske agense. Svrha rada bila je ispitati gubitak mase uzoraka četiriju različitih dentalnih keramika u kiselom mediju. Najmanji gubitak mase izmjeren je kod apatitne staklo-keramike (IPS-Empress 2 za slojevanje) (4,9±0,3 μg/cm2), a najveći kod glinične keramike (Vitadur alpha) (15,0±0,2 μg/cm2). Litijska disilikatna staklo-keramika (IPS-Empress 2 za bojenje) i glinična (IPSClassic) pokazale su vrlo slične rezultate (9,4±3,4 μg/cm2 i 10,1±0,3 μg/cm2). Vrijednosti gubitka mase uzoraka u ovom radu, kao i u većini pronađenih u literaturi, minimalne su, te vjerojatno nemaju kliničke i toksikološke posljedice. Ali, to ne znači da se mogu uopćavati i prenositi na neispitane vrste dentalne keramike.Dental materials need to be thoroughly examined in order to assess their long-term therapeutical value. Chemical degradation of dental ceramic material enhances its roughness, leading to the wear of the opposing natural tooth or restorative material, greater plaque attachment to ceramics, weakening of the ceramic structure causing the critical ion exchange at the surface and enhancing the sensitivity to future chemical agents. The aim of this study was to test loss of mass in samples of four different dental ceramic materials in an acid medium. The least mass loss was recorded in apatite glass ceramic (IPS-Empress 2 for layering) (4.9±0.3 μg/cm2), and most mass loss was recorded in alumina ceramic (Vitadur alpha) (15±0.2 μg/cm2). Lithium disilicate glass ceramic (IPS-Empress 2 for coloring) and alumina (IPS-Classic) showed very similar results (9.4±3.4 μg/cm2 and 10.1±0.3 μg/cm2). The values of mass loss in samples in this work, as well as in the most of the literature, are minimal and presumably do not have any clinical or toxicological effects. However, it does not imply that these values can be generalized and transferred to dental ceramic materials that were not yet analyzed

Macroscopic Analysis of Co-Cr Base Alloys Joints

Kobalt-kromove legure standardni su gradivni materijal za proteze. Prekid tehničke ili funkcijske trajnosti toga protetičkog rada može se popraviti lemljenjem ili zavarivanjem. Svrha rada bila je ocijeniti makroskopski izgled lemišta i zavara odljevaka triju Co-Cr legura za izradu protezne baze. Zbog toga su po tri uzorka svake legure (32x10x1,5 mm) prerezana po sredini i spojena na mjestu reza lemljenjem, laserom i elektrolučno (TIG-om). Svi spojevi imali su „I“ oblik i rabljen je dodatni materijal. Spojene površine analizirane su svjetlosnim mikroskopom pod povećanjem od 50 do 200 puta. S makroskopskog stajališta, lemljenje svih uzoraka bilo je uspješno. Na zavarenim uzorcima, spajanima laserom ili TIG-om, uočljivo je bilo nedovoljno preklapanje točkastih udara, te pukotine i pore. To upućuje na to da je potrebno pravilno rukovati s uzorcima i optimizirati parametre (trajanje impulsa, napon i snagu) za svaki način spajanja i analiziranu leguru. Makroskopska ocjena kvalitete spoja što ga obavlja zubni tehničar, jedan je od čimbenika u procjeni funkcijske trajnosti protetičke konstrukcije.Cobalt-chromium alloys are used as standard restorative material in prosthodontics. Some errors in laboratory procedure or breaks of metallic parts during functional period must be repaired. The purpose of this study was to compare joint quality, obtained by different thermal techniques on Co-Cr as cast alloy. Three samples (32x 10 x 1,5 mm) of each alloy were cut and joined by soldering, laser and Tungsten Inert Gas (TIG) welding. All samples were I-shaped. The connested surfaces were analysed by microscope, under 50 - 200 X magnification. From the macroscopic view, soldering of all specimens was successful. On the welded samples, either by laser or by TIG welding, overlapping of welding spots was insufficient, cracks and porosity were present. There is a need for proper handling and optimization of all parameters (impulse duration, voltage and power) for each applied method and for analysed alloys. It could be concluded that macroscopic analysis of the quality of joint, done by technician, is one of the aspects to predict the functional durability of prosthetic construction