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

In memoriam Prof. Vladimir Lapter 1923 - 2002

Rođen je 21. travnja 1923. godine u Varaždinu, gdje je polazio osnovnu školu i gimnaziju. Godine 1945. upisuje Medicinski fakultet Sveučilišta u Zagrebu i diplomira 1952. godine. Nakon liječničkog staža i obveznog terenskog rada (1952.-1954.) započinje na Klinici za maksilofacijalnu kirurgiju kod akademika prof.dr. Ive Čupara specijalizaciju iz stomatologije i polaže specijalistički ispit 1957. godine. U jesen iste godine počinje akademsku karijeru kao asistent u Zavodu za ortodonciju, gdje je bio do umirovljenja. Godine 1964. postaje sveučilišni docent nakon redovitog habilitacijskog postupka i obrane habilitacijskog rada: “Utjecaj jezika na razvoj gornje čeljusti i zubnog luka kod urođenog rascjepa”.Prof. Lapter was born on 21 April 1923 in Varaædin, where he attended primary and high school. In 1945 he enrolled at the School of Medicine University of Zagreb and graduated in 1952. After obligatory medical practice and fieldwork (1952-1954) he began specialising in dental medicine at the Clinic of Maxillofacial Surgery under Academician Prof. Ivo Čupar, and passed the specialist examination in 1957. In the autumn of the same year he started his academic career as Assistant in the Department of Orthodontics, where he worked until retirement. In 1964 he became Senior Lecturer after defending his thesis “The Effect of the Tongue on Development of the Maxilla and Dental Arch in Congenital Cleft”

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

Gradual Loss of Partial Denture Retentive Forces

Djelomična proteza može se fiziološki ispravno prilagoditi fundamentu samo na osnovi poznavanja biostatike stomatognatoga sustava. Velik broj čimbenika utječe hoće li neka sila biti u funkciji fiziološke stimulacije ili će prouzročiti patološke promjene potpornoga tkiva. Ovim istraživanjem namjerava se utvrditi početna vrijednost retencijskih sila lijevanih kvačica, ankera i magneta, te njihov postupni gubitak sile nakon određenoga broja ciklusa vađenja i stavljanja retencijskih elemenata. Mjerenja su provedena u Zavodu za materijale Fakulteta za strojarstvo i brodogradnju Sveučilišta u Zagrebu. Ispitivani uzorci izrađeni su od materijala i gotovih elemenata prema podatcima proizvođača. Odgovaraju kriterijima koje zahtijeva DIN 13912 i DIN 13906-1 i ostalim internacionalnim standardima. Uređajem za mjerenje retencijske sile može se ciklički uključivati i isključivati retencijske elemente i kontinuirano prikupljati mjerne podatke. Ovim mjerenjima istraživao se postupni gubitak sila ispitivanih retncijskih elemenata. Dobivene vrijednosti kvalitativne raščlambe ispitivanih retencijskih elemenata prikazane su grafički i u tablicama. Tijekom ispitivanje došlo se do spoznaje da vrijednost retencijske sile kvačica i ankera postupno opada, a da se sila magnetskih slitina ne mijenja. Temeljni čimbenik koji bitno utječe na veličinu retencijske sile jest trošenje i zamor materijala. Spojnica uz nazočnost sline ima manju silu retencije, ali zbog smanjena trošenja nastat će i sporije smanjenje retencijske sile.A partial denture can be oppropriately accommodated physiologically on the denture base only with good understanding of the stomatognathic system biostatics. A force can either act as a physiological stimulus or can lead to pathological alterations in supporting tissue, wich depends on a great number of factors. The aim of the study was to determine the initial retentive force values of cast clasps, anchors and magnets as wel as their gradual loss of force after a certain number of retentive elements, extraction and insertion cycles. Measurement were carried out at the Materials Department, School Engineering and Naval Architecture, University of Zagreb. The examined specimens were made of materials and ready-made elements in accordance with the manufacturer’s declaration. They satisfy the DIN 13912 and DIN 13906-1 criteria and comply with other international standards. The device for retentive force measurement can periodically both include and exclude retentive elements thus continually collecting measurement data. Gradual loss of the examined retentive element forces was analysed by these measurings. The obtained values of the examined retentive elements qualitative analysis are presented in graphs and tables. In the course of analysis it was dicovered that the retentive force value of both clasps and anchors gradually decreases whereas the magnetic force of the alloys remains unchanged. The key factors which have a great impact on the retnetive force value are wear and material fatigue. A clasp in a wet environment (saliva) has less retentive force, but due to decreased wear the retnetive force decrease will progress more slowly

Verletzungen der orofazialen Struktur in der ausgewählten Stichprobe der Handballspieler

Injuries of the orofacial tissue frequently occur in many sports, and the possibility of orofacial injury during the sports season amounts to 10%, and throughout a career 33% to 56%. The aim of the present study was to determine the frequency and seriousness of injury of the orofacial structure in a selected population of top handball players (Croatian National Team). The study was carried out via a questionnaire which each player completed(15 players). The total number of injuries of the orofacial structure was 132 injuries, i.e. 8.8 for each player during his career, During the last year 8 injuries have been recorded, which corresponds to the average of several years. The most frequent injuries were lacerations of the lips, tongue and face, which comprised almost 79% of all injuries. The frequency of injury also depends on the position in the team, and consequently goalkeepers were most often injured, followed by field players and then pivot players, while wings were the least frequently injured. Medical intervention was needed in only five cases. When comparing the injuries reported in this investigation with those received by the Croatian Premier League water-polo players similarity was observed in the frequency of injuries to the orofacial structures and also the lack of protective equipment during matches. Injuries which are relatively slight and only occasionally require medical intervention, have a non stimulating effect on the utilization of protective equipment - mouthguards. All injuries to the teeth could be prevented or at least diminished by use of a mouthguard. This study, on such a small but specific sample, has proved that the need has arisen for a further study on a considerably larger sample of handball players.Verletzungen des orofazialen Gewebes kommen in vielen Sportarten vor. Für den Sportler steht die Wahrscheinlichkeit, eine orofaziale Verletzung abzubekommen, bei 10% pro Sportsaison und bei 33%-56% in der ganzen Sportkarriere. Das Ziel dieser Studie war, die Häufigkeit und die Schwere der orofazialen Verletzungen in der ausgewählten Stichprobe der Leistungshandballspieler (kroatische Nationalmannschaft) zu bestimmen. Die Studie wurde mittels eines Fragebogens durchgeführt, den jeder der 15 Spieler ausfüllte. Es wurden im total 132 Verletzungen der orofazialen Strukturangemeldet, d.h. 8,8 pro Spieler in seiner Karriere. In der letzten Saison kamen 8 Verletzungen vor; eine Zahl, die mit dem Durchschnitt von mehreren Jahren übereinstimmt. Die häufigsten Verletzungen waren Lippen-, Zungen- und Gesichtsrisse, die zusammen 79% aller angemeldeten Verletzungen machen. Die Häufigkeit der Verletzungen hangt auch von der Spielposition ab, so dass Torwarte am häufigsten verletzt wurden, von Feldspielern und Pivotspielern gefolgt, während Außenspieler ziemlich wenige Verletzungen abbekamen. Ärztliche Intervention wurde nur in fünf Fallen nötig. Vergleicht man die in dieser Studie beobachteten Verletzungen mit den Verletzungen von Wasserballspielern der Ersten Wasserballliga, sind die Ähnlichkeiten in der Häufigkeit orofazialer Verletzungen sowie in der mangelden Schutzausrüstung beim Spiel bemerkbar. Die ziemlich leichte Verletzungen, die nur ausnahmsweise ärztliche Hilfe ben6tigen, wirken nicht stimulierend auf den Gebrauch der Mundschutzausrüstung. Alle Zahnverletzungen konnten mit so einer Mundmaske vermieden oder zumindest vermindert werden. Da die Ergebnisse dieser Studie auf einer kleinen aber spezifische Stichprobe interessant sind, erwies sich der Bedarf nach weiteren Studien auf einer bedeutend größeren Stichprobe der Handballspieler

A Quantitative Evaluation of the Distal Displacement of the Gingival Zenith in the Maxillary Anterior Teeth

The aim of this study was to quantify the specific distal displacement of the gingival zenith in the maxillary anterior dentition. Bilateral measurements, taken with a digital caliper in maxillary stone casts were recorded in six maxillary anterior teeth to evaluate distal displacement of the gingival zenith in relation to the long axis of the crowns. The gingival zenith was distally displaced between 0.45 and 1.01 mm in 90%, 85% and 60% of the central incisors, lateral incisors and canines, respectively. Contralateral comparisons between the tooth groups revealed significantly larger distal displacement of the zenith in left canine (p<0.05). Ipsilateral comparisons revealed that the lateral displacement of the zenith was significantly larger in central than in lateral incisors (p<0.05). Similarly, the zenith of lateral incisors was displaced significantly more distal than that of canine teeth (p<0.05). Comparisons of the frequency of coincidence of the position of the gingival zenith with the long axis of the tooth revealed that it was significantly greater in canines than in lateral and central incisors (p<0.05). The frequency and magnitude of distal displacement is tooth-dependent and larger in central than in lateral incisors, which in turn, is larger than in canines. These data could be used as reference points during esthetic anterior oral rehabilitation, especially in case of porcelain laminate veneers

Effect of Prosthesis Lateral Movement on the Value of Magnetic Retention Force

Retencija i način njezinog mjerenja kod mobilnih proteza odavno su privlačili pozornost brojnih istraživača. Ovo ispitivanje poduzeto je s namjerom da se utvrdi utjecaj lateralnih pomaka proteze na konačnu vrijednost retencije koju dobijemo s pomoću magnetskih legura. Istraživanja su obavljena na uzorku od 157 parova magnetskih legura na čiju su privlačnu magnetsku silu utjecale lateralne sile.Mjerenja su obavljena na Institutu za fiziku Sveučilišta u Zagrebu. Svi uzorci magnetskih legura su neoštećeni, točnih promjera i visina, zaglađenih i poliranih površina. Promjeri magneta kretali su se od 4 do 7,1 mm. Visine mjernih magneta bile su 2, 2,5 i 3 mm. Na uzorku su mjerene vrijednosti retencijskih sila između dva SmCo5 magneta jednakih ili različitih dimenzija. Mjerenja su izvođena na magnetskom dinamometru, aparaturi konstruiranoj u tu svrhu. Prosječna vrijednost retencije u uzorku s lateralnim pomakom magneta, pri razmaku od 0,4 mm, iznosila je 1,71 N, pri razmaku od 1 mm 1,31 N, a pri razmaku od 1,6 mm 1,08 N.Retention and methods of its measurement in mobile prostheses have long attracted attention of many investigators. The aim of this study was to determine the effect of prosthesis lateral shifts on the retention final value obtained by magnetic alloys. Experiments were performed in a sample of 157 pairs of magnetic alloys, their magnetic force being influenced by lateral forces. Measurements were carried out at the Institute of Physics, University of Zagreb. All magnetic alloy specimens were intact, of exact diameter and height, and of smooth and polished surface. Magnet diameter ranged from 4-7.1 mm, and their height was 2, 2.5 and 3 mm. The values of retention forces between two SmCo5 magnets of identical or different dimensions were measured in the sample. The measurements were performed on a magnetic dynamometer, a device constructed for this purpose. The mean value of retention in the sample with lateral magnet shift was 1.71, 1.31 and 1.08 N at a distance of 0.4, 1 and 1.6 mm, respectively

Die Position der Neigung der Kondylenbahn im verhältniss zum weitesten durchmesser der Gelenkgrube des TM-gelenkes

Autori su izvršili komparaciju nagiba kondilne staze i nagiba najšireg dijela fosse articularis, od mediosagitalne ravnine, pripadnika naše nacionalne skupine. Ispitali su i stupanj korelacije tih varijabla. Na temelju svojih ispitivanja, predlažu otklon centralne zrake, u vrijednosti od 161 lučnog stupnja, rendgenograma, na kojima se želi dobiti precizna istovremena tangencijska snimka kondilne staze i aksijalna snimka najšireg dijametra fosse articularis i kondila, s time da vrijednost od 161 lučnog stupnja predstavlja otklon centralne zrake od mediosagitalne ravnine, koju registriramo s početnih 0 stupnjeva, koji se nalaze na torusu occipitalisu.The authors have compared the inclination of the condyle path and the inclination of the widest part of the fossa articularis from the median sagittal plane, in our population. They have investigated the degree of correlation of the found variables. Based on their findings, they propose a deflection of the central beam in the value of 161 arcus degree in x-rays if it is required at the same time to obtain a precise tangential picture of the condyle path and an axial finding of the widest diameter of the fossa articularis and the condyle. The value of 161 arcus degree represents the deflection of the central beam from the median sagittal plane which is registered beginning on zero degree at the torus occipitalis.Die Autoren haben die Neigung der Gelenkbahn mit der Neigung der grössten Breite der Gelenkgrube in Abhängigkeit von der mesiosagittalen Ebene, verglichen. Der Grad der Korrelation dieser Variabilen wurde ebenfalls untersucht. Aufgrund dieser Untersuchungen wird eine Abweichung des Zentralstrahls im Werte von 161 Bogengrade für Röntgenaufnahmen welche gleichzeitig eine tangentiale Aufnahme der Kondylenbahn und eine axiale Aufnahme des breitesten Diameters der Gelenkbahn darstellen soll, empfohlen. Der Wert von 161 Bogengrad ist die Abweichung des Zentralstrahls von der mediosagittalen Ebene, welche mit O Grad als Ausgangspunkt am Torus occipitalis registriert wird