(1) Background: This study evaluates the effect of a conventional/low-voltage light-curing protocol (LV protocol) (10 s with 1340 mW/cm2) and high-voltage light-curing protocol (HV protocol) (3 s with 3440 mW/cm2) on the microhardness (MH) of dental resin-based composites (RBCs). Five resin composites were tested: conventional Evetric (EVT), Tetric Prime (TP), Tetric Evo Flow (TEF), bulk-fill Tetric Power Fill (PFL), and Tetric Power Flow (PFW). (2) Materials and Methods: Two tested composites (PFW and PFL) were designed for high-intensity light curing. The samples were made in the laboratory in specially designed cylindrical molds; diameter = 6 mm and height = 2 or 4 mm, depending on the type of composite. Initial MH was measured on the top and bottom surfaces of composite specimens 24 h after light curing using a digital microhardness tester (QNESS 60 M EVO, ATM Qness GmbH, Mammelzen, Germany). The correlation between the filler content (wt%, vol%) and the MH of the RBCs was tested. For the calculation of depth-dependent curing effectiveness, the bottom/top ratio for initial MH was used. (3) Conclusions: MH of RBCs is more dependent on material composition than on light-curing protocol. Filler wt% has a greater influence on MH values compared to filler vol%. The bottom/top ratio showed values over 80% for bulk composites, while for conventional sculptable composites, borderline or suboptimal values were measured for both curing protocols.
Abstract Objectives The aim of the study was to analyze the occurrence of stress on teeth with abfraction lesions restored with six different restorative materials, and by introducing the tensile strength parameters to calculate the safety factor of the material under the load (ratio between the strength of the material and the maximum stress). Materials and Methods Three-dimensional models of the mandibular premolar are created from a microcomputed tomography images. An abfraction lesion is modeled on the tooth. The stress of the dental tissues and six restorative materials under functional and nonfunctional occlusal loading of 200 (N) are analyzed by finite element method. Statistical Analysis CTAn program 1.10 and ANSYS Workbench (version 14.0) were used for analysis. Results are presented in von Mises stress. Results Oblique loads caused ≈ four times higher stress in restorative materials than the axial ones. It is noticeable that high values of von Mises stress are measured at the bottom of the sharp lesion, even up to 240 MPa, that are significantly reduced after the restoration. The highest stresses at the restorative material are present at the lower (gingival) margin of the restoration. The highest stresses under both types of loads are measured in nanohybrid composite (Tetric EvoCeram, Ivoclar Vivadent). The lowest values of the stress are measured in the flowable composite (Tetric Flow, Ivoclar Vivadent), but at the same time, the highest value of the stress is measured in the surrounding dental tissues on the tooth restored with the flowable composite. The microhybrid composite (Herculite XR, Kerr), with the highest safety factor, is the material that best withstands the stresses it is exposed to. The obtained safety factor did not exceed the critical limit, except for the glass ionomer cement, with the safety factor lower than 1. Conclusion The type of tooth loading has the greatest influence on the intensity of stress. The value of the obtained stresses in the restorative material and dental tissues differ due to the different mechanical properties of the materials. Restoration of noncarious lesions significantly reduces extremely high stress values at their bottom.
OBJECTIVE The aim of this paper was to analyze the distribution of stress and deformation on the mandibular first premolar under two types of loading (axial and para-axial load of 200 N) using the FEM computer method. MATERIALS AND METHOD For this research a µCT scan of the first mandibular premolar was used, and the method used in this research was FEM analysis under two types of loading. RESULTS The values of the von Mises stress measured in the cervical part of an intact tooth under axial load were up to 12 MPa, and under paraaxial load over 50 MPa. The values of the stress measured on the bottom of the noncarious lesion are very high ≈ 240 Mpa. Stress values in the cervical part of the intact tooth are higher in the zone of the sub-surface enamel. The deformation values of the tooth under para-axial loading were ≈ 10 times higher than the value of the deformation under axial load. The greatest deformations were seen in the area of the tooth crown. CONCLUSIONS Occlusal loading leads to significant stress in the cervical part of teeth. The values of the measured stress are greater under the action of paraxial load. The values of stress in abfraction lesions measured under a paraxial load are extremely high. Exposing the lesion to further stress will lead to its deepening. The total deformation of the entire tooth under paraxial load was ≈ 10 times higher compared to the deformation value of the tooth under axial load.
Aim of this study was to examine the existence of sexual dimorphism of the first permanent maxillary molars in the population of central Bosnia. The sample for the study comprised 94 subjects with intact crowns of the first permanent maxillary molars, without orthodontic anomalies. Mesiodistal and buccopalatal diameters were measured on the plaster models, based on calculated variables: robustness index or crown area (IRC) and sexual dimorphism (SD). Linear dimensions of the first permanent maxillary molars, as well as the IRC exhibited sexual dimorphism with larger values in males, except MD diameter on the left side. The greatest sexual dimorphism demonstrates IRC from the right. Linear dimensions of the first permanent maxillary molars and IRC can be used for sex determination in population of Central Bosnia.
Aims: In this study, a sample of 28 patients followed the clinical functionality and durability of inlay fiber-reniforced composite (FRC) bridge restorations, laboratory fabricated, for a period of 7 years. Materials and Methods: Patients with the loss of a first molar in the posterior region were selected for the study. Fabrications of FRC structures were made of longitudinal and woven fibers and ceramic optimized polymer material was used for veneering. Statistical Analysis Used: The restorations were evaluated using the modified United States Public Health Service (USPHS) parameters system for the clinical evaluation of dental restorative materials. Kaplan-Meier survival test was used for analyzing the data. Results: During the evaluation period, no fracture of the FRC construction was found. At all tested restorations, significant color change of the Ceromer veneering material was observed. During the investigation time, the color of the restorations became slightly lighter, with loss of gloss. In two patients, a chip off from the veneered material was noticed after 4 years, in three patients over 5 years and in three patients after 6 years. Conclusions: FRC-Ceromer inlay fixed prosthetic restorations for a period of 7 years showed acceptable clinical durability and functionality. Clinical Relevance to Interdisciplinary Dentistry Fiber reinforced composite inlay restorations for a period of seven years showed exceptional durability and functionality with minimal preparation of the abutment teeth. FRC restorations present an acceptable alternative to the classical construction of the metal ceramic or full ceramic bridge which needs to make preparation with extensive reduction of the abutment teeth.
Adresa za dopisivanje Alma Dozic ACTA, Academic Center for Dentistry in Amsterdam Department of Dental Materials Gustav Mahlerlaan 3004 1081 LA Amsterdam, Netherland a.dozic@acta.nl Sažetak Ljudski zubi građeni su od organskih i anorganskih tkivnih komponenata sličnih kostima. Može se pretpostaviti da strukturalna promjena boje zuba u različitim prirodnim uvjetima može poslužiti u forenzičnoj tafonomiji kao, na primjer, u slučaju kad se potvrđuje okoliš i uvjeti ukopa te vrijeme provedeno nakon smrti (PMI-a). Danas se uočavaju i vrlo male promjene u nijansi zuba zahvaljajući dobro razvijenim dentalnim spekrtofotometrima. Poznato je da zubi, ako su izloženi utjecaju zraka, brzo dehidriraju, ali stupanj i način tih promjena u vremenskom intervalu dosad nije objektivno izmjeren. Svrha istraživanja: Svrha ovog istraživanja bila je odrediti stupanj i obrazac promjene boja zuba izloženih određeno vrijeme trima različitim uvjetima. Materijal i postupci: Za istraživanje su odabrani impaktirani treći kutnjaci zato što do tada nisu bili izloženi okolišnim uvjetima. Njihove vrijednosti CIE L*a*b* nakon ekspozicije u suhim uvjetima, natrijevu kloridu (NaCl) i umjetnoj slini (kontrola) izmjerio je iskusni stručnjak dentalnim spektrofotometrom u razmacima od 1 sat, 24 sata, 1 tjedan, 3 tjedna, 5 tjedana i 7 tjedana. Rezultati: Vrijednosti koordinata za L*-lightness (svjetlost) i b*-blue-yellow (plavo-žutu boju) bile su znatno povišene u suhim uvjetima (p < ,001 za svjetlost i p ≤ ,050 za boju), a koordinate za a*-green-red (zeleno-crveno) nisu pokazale statistički značajan pomak. Izloženost ekstrahiranih trećih kutnjaka suhim uvjetima prouzročila je veliko povećanje kordinata L* i b* prema svjetlijem i žućem dijelu, u usporedbi s izloženošću zuba umjetnoj slini i natrijevu kloridu, u svim testiranim uvjetima koordinata a* pokazala se kao vrlo promjenljiva. Zaključak: Izloženost ekstrahiranih impaktiranih umnjaka suhim uvjetima uzrokovala je znatno uzastopno povećanje vrijednosti L* i b* u usporedbi s izloženošću zuba natrijevu kloridu i umjetnoj slini. Ključne riječi forenzička stomatologija; smrt; vlaga; zub; odontometrija; kolorimetrija 1 ACTA – Stomatološki akademski centar u Amsterdamu, Zavod za dentalne materijale, Amsterdam, Nizozemska ACTA, Academic Center for Dentistry in Amsterdam, Department of Dental Materials, Amsterdam, Netherland 2 Stomatološki fakultet Sveučilišta u Sarajevu, BiH Faculty of Dentistry, University of Sarajevo, Bosnia and Herzegovina 3 Zavod za sudsku medicinu i kriminalistiku Medicinskog fakulteta Sveučilišta u Rijeci, Hrvatska Department of Forensic Medicine and Criminalistics, Rijeka University School of Medicine, Croatia
Human teeth consist of organic and anorganic tissue components similair to bones. Therefore, it is assumable that the registration of structural changes of teeth color in different enviromental conditions may prove useful within forensic taphonomy field, for example, for verification of burial environment and postmortem interval (PMI). Registration of very smal alterations of teeth color is nowadays possible due to well developed dental spectrophotometers. It is known that teeth exposed to air quickly dehydrate, but the degree and the pattern of these color changes in time intervals have not been objectively measured. Purpose: The objective was to determine the degree and patern of color alterations of teeth exposed to three different conditions in time. Material and Methods: The impacted third molars were used in this study because they were not previously exposed to any enviromental conditions. Their CIE L*a*b* values after exposure to dry conditions, NaCl and artificial saliva (control) were measured with dental spectrophotometer in time intervals of 1 hour, 24 hours, 1 week, 3 weeks, 5 weeks and 7 weeks by one trained operator. Results: The L*-lightness and the b*-blue-yellow color coordinate increased in dry conditions (p < .001 and p ≤ .050 respectively), which was statistically significant, whereas a*-green-red color coordinate showed shifts of color in this condition which were not statistically significant. The exposure of extracted third molars to dry conditions caused significant increase of L* and b* color coordinate towards more light and more yellow in comparison to the exposure of teeth to artificial saliva and NaCl. The a* color coordinate displayed high variability of its alteration in all tested conditions. Conclusions: The exposure of extracted impacted wisdom teeth to dry conditions caused a considerable consecutive increase of lightness (L*) and blueness-yellowness (b*) in comparison with the exposure of teeth to NaCl and artificial saliva.
Estimation of age is standard procedure during forensic exa-mination. Dental methods can be used to estimate age. There is a wide range of such methods. The oldest dental method of age esti-mation in adults was described by Gustafson in 1950 (1, 2, 3, 4). This is the first method that proposed using statistical methods in cal-culating age on the basis of teeth. In 1994 and 1995, Kvaal and Sol-heim worked on using dental ra-diography to estimate age. These non-sectioned or non-destruc-tive methods of age estimation are highly regarded in archaeological studies and in identifying living persons where we cannot afford to “sacrifice” a tooth (5, 6, 7). The main focus of method proposed by Kvaal and Solheim is on regres -sive changes that are visible on ra -diographs. For example, deposi-tion of secondary dentin results in decrees of pulp cavity. Measuring the dimensions of the pulp cavity on radiographs can indirectly give an estimate of the quantity of sec-ondary dentin (5, 6, 8). One have to have in mind that radiographs are part of standard dental pa-tients records, so it is important to search for different ways of exami-nation in order to obtain more an -te-mortem and post-mortem in-formation.There are many ongoing re-search projects in the world to-day dealing with issues of age es-timation. Most are based on Gus-tafson’s criteria, individual or variously combined and in con-junction with different statistical methods. It is believed that dif-ferent techniques, new methods and using statistical methods pre -vents subjective judgments by re-searchers and enables more pre-cise age estimation. The VSC 5000
Throughout the history of the dentistry, dental amalgam represents the most often used restorative material. However, the fact that one of its main components is mercury is the cause of the intensive discussions about the safety of these restorative materials and during the last 150 years polarizes the professional and scientific circles. Proamalgamists consider amalgam safe and useful material, but antiamalgamists mark it as cause of the whole spectrum of diseases. The wish of the authors was that, through the presentation of the literature published from the nineties of the last century to date, present the review of this very issue, which still causes the dilemma in the modern dentistry.
A non-carious cervical lesion ( NCCL) is defined as loss of dental hard tissue in the cervical part of the tooth, not caused by caries, multicausal and insufficiently clarified etiology. Identification of specific etiological factors NCCL is a key in making decisions about treatment. The authors conducted a study to evaluate the prevalence and distribution of noncarious cervical lesions in adults. Material and Methods: The sample of 210 respondents, were divided into three age groups. Clinical inspection has determined the distribution of NCCL within the respondents in relation to their age, teeth groups, vestibular and oral surfaces of the teeth, sides of the jaws and expression of NCCL according to the tooth wear Smith– Knight Index. Results: This research points to a very common finding NCCL within our respondents. Cervical lesions were diagnosed in 78.6% respondents in the first, 91.4% in the second and 97.2% in the third group. It has been shown that the number and expression of cervical lesions increases with age of respondents. Noncarious cervical lesions are usually the most visible on premolars, furthermore the first molars and canines, the second molars and then incisors. The minimum number of lesions were diagnosed in the third molars. Conclusion: Given the high prevalence of NCCL’s, there are reasonable grounds for introducing the tooth wear Index to the wider clinical practice, recording noncarious cervical lesions in dental records, creating specific prevention strategies and effective treatments.
The aim of our study was to establish the prevalence of dental anomalies among the student population at the Faculty of Dentistry of Sarajevo University. The aim of the research was to find out the most common dental anomalies in this particular group. The participants were 268 students at the Faculty of Dentistry. The examined students came from different regions of Bosnia and Herzegovina. The students were examined by the dentists employed at the Faculty while the findings were recorded on charts created specifically for this purpose and in accordance with the recommendations of WHO (World Health Organization). The students’ age ranged from 18 to 23. The results were statistically analyzed, and compared with the relevant facts from the literature. Our conclusion is that the most prevalent dental anomalies pertain to the teeth position (54%) followed by the teeth crowding at ICS (intercanine segment) (50%). The most negligible changes were found in the tooth shape, and this could be accounted for by the anthropological changes of the human teeth.
Nema pronađenih rezultata, molimo da izmjenite uslove pretrage i pokušate ponovo!
Ova stranica koristi kolačiće da bi vam pružila najbolje iskustvo
Saznaj više