Purpose
To evaluate and compare the mechanical properties (flexural strength and surface hardness) of different materials and technologies for denture base fabrication. The study emphasized the ...digital technologies of computer‐aided design/computer‐aided manufacturing (CAD/CAM) and three‐dimensional (3D) printing.
Materials and Methods
A total of 160 rectangular specimens were fabricated from three conventional heat‐polymerized (ProBase Hot, Paladon 65, and Interacryl Hot), three CAD/CAM produced (IvoBase CAD, Interdent CC disc PMMA, and Polident CAD/CAM disc), one 3D‐printed (NextDent Base), and one polyamide material (Vertex ThermoSens) for denture base fabrication. The flexural strength test was the three‐point flexure test, while hardness testing was conducted using the Brinell method. The data were analyzed using descriptive and analytical statistics (α = 0.05).
Results
During flexural testing, the IvoBase CAD and Vertex ThermoSens specimens did not fracture during loading. The flexural strength values of the other groups ranged from 71.7 ± 7.4 MPa to 111.9 ± 4.3 MPa. The surface hardness values ranged from 67.13 ± 10.64 MPa to 145.66 ± 2.22 MPa. There were significant differences between the tested materials for both flexural strength and surface hardness. There were also differences between some materials with the same polymerization type. CAD/CAM and polyamide materials had the highest flexural strength values. Two groups of CAD/CAM materials had the highest surface hardness values, while a third, along with the polyamide material, had the lowest. The 3D‐printed materials had the lowest flexural strength values.
Conclusions
Generally, CAD/CAM materials show better mechanical properties than heat‐polymerized and 3D‐printed acrylics do. Nevertheless, a material's polymerization type is no guarantee of its optimal mechanical properties.
Implant abutment selection is an important step in implant treatment to restore one or more lost teeth. The aim of this study was to compare stock and individual CAD/CAM full-form abutments after one ...year in function. A total of 64 subjects with one missing tooth were divided into two groups according to the type of abutment: 34 patients were given a stock abutment, and 30 an individual CAD/CAM abutment. Patients were scheduled for check-ups seven days after functional loading and after four, eight, and twelve months. Peri-implant soft tissue status was checked at every check-up by monitoring parameters traditionally used in similar studies: plaque index; bleeding on probing; and probing depth. To assess the stability of the bone tissue, radiological methods of measuring the amount of bone level compared to the implant shoulder were used. When needed, data were analysed by χ2 test or by Fisher’s exact test. The normality of the distribution of quantitative measurements (properties) was tested by the Shapiro–Wilk test. Differences in the distribution of quantitative variables frequencies were analysed by Student’s t-test. Student’s t-test was used for repeated measurements, Mann–Whitney’s U test and ANOVA test for repeated measurements, and Friedmann’s two-way analysis of variance for repeated measurements. The predictive values of the chosen variables on the ABI index were assessed by the logistic regression model (Enter method). The results of this study showed that the impact of the abutment type (individual CAD/CAM or stock) on the average bleeding on probing was significant, especially after eight or twelve months. However, the abutment type did not show a significant correlation with the total crestal bone loss. The level of oral hygiene showed a significant correlation with the average bleeding on probing. The influence of smoking cigarettes on the total crestal bone loss evaluation was also significant. Overall, from a clinical perspective, custom CAD/CAM abutment performed slightly better than stock abutments during the one-year follow-up.
Programming of joint mechanism/parameters (sagittal condylar inclination and Bennett angle) of adjustable dental articulators is a prerequisite for performing positions and movements of the mandible. ...The aim of the study was to test significant differences between the two methods (wax eccentric records and Arcus Digma device) of measuring these joint parameters by using three different dental articulators (SAM 3, Protar 7; and Artex CR).
Thirty asymptomatic younger (age 25.7 ± 2.9 years) subjects (dental medicine students) divided by gender, with normal occlusion (Angle class I) participated in the study. After taking anatomical impressions of both dental arches, master casts were made of hard dental plaster for each subject. The values of the left and right sagittal condylar inclination and Bennett angle by the two methods of wax eccentric protrusive and lateral records and Arcus Digma device were measured for the purpose of programming the mentioned joint parameters in three different articulator systems.
The average values of the measured parameters of sagittal condylar inclination and Bennett angle of wax eccentric records were higher (ranging from 5ºto 10º) in relation to the values measured by Arcus Digma device. Statistically significant differences found between the measured joint parameters (p <0.025) were influenced by the articulator system design and measurement methods (t-test for dependent samples and MANOVA).
The use of Arcus Digma device should be considered reliable and valid for individualized programming of dental articulators, rather than the use of wax eccentric records.
The objective of this pilot study was to examine the impact of occlusal splint treatment on mandibular border movements and the condyle position in subjects with bruxism.
The study included 9 ...subjects diagnosed with bruxism (mean age 28.7) and 9 subjects in the control group (mean age 30.5). All subjects were adults, eugnathic, and with a dentoalveolar Angle Class I, without prosthetic restorations, previous or current orthodontic treatments, a systemic disease or previous surgical interventions in the temporomandibular joint. All experimental and control group subjects were provided with a standardized relaxation occlusal splint, which they wore for 8 weeks. During this time, an initial and three additional measurements of incisal opening (IO), left condyle opening (OLC), right condyle opening (ORC), left laterotrusion (LLI) and right laterotrusion (LRI) (after 2, 4 and 8 weeks) were performed using an Arcus Digamma II (Kavo) ultrasound device for mandibular movements recording. Using the same instrument, the condylar position during protrusion, left and right laterotrusion, and in the centric relation position (CR) was analyzed initially and after 8 weeks using the maximum intercuspation as reference point. Continuous variables were described using basic statistical parameters, and the statistical significance of differences between the variables was checked by the t-test and χ2 test (p <0.05).
The values of IO, OLC, ORC, LLI and LRI increased after 8 weeks of wearing, with the highest increase for OLC, by 13.8%. No statistically significant difference (p <0.05) was found for any changes in movements. Changes in the condyle position during all movements and those in the CR were higher in the experimental group for 10 out of 14 measured parameters compared to the control group. A statistically significant difference was established for 5 out of 14 measured parameters after the occlusal splint treatment.
The results of this pilot study have proven the influence of the occlusal splint treatment on mandibular border movements in subjects with bruxism by increasing the range of movements. Also the changes of the condyle position in subjects with bruxism were greater compared to those in healthy subjects.
Tooth loss can cause loss of occlusal, masticatory, esthetic, physiognomic, phonetic and psychosocial function of patients. The most frequently used treatment method of completely edentulous patients ...and patients with a small number of remaining teeth are complete dentures or overdentures. One of the most important clinical and laboratory procedures in their fabrication is functional impression taking. The aim of this paper was to present procedures of taking functional impressions in fabrication of complete dentures and overdentures, using standardized techniques and materials. An accurate functional impression together with other correctly performed clinical and laboratory procedures ensure good retention and stability of dentures, which is a precondition for restoring patients' lost functions.
The purpose of this investigation was to study sagittal condylar inclination values within a uniform sample (Angle class I occlusion) using 'articulator-related registration' and Camper's plane as a ...reference plane. The study was performed on a sample of 58 Angle class I subjects (mean age 25.1, SD 3.1). Measurements were performed with an ultrasonic jaw tracking device with six degrees of freedom. After a paraocclusal tray was fixed in the mouth, each subject had to make three protrusive movements and three right and left laterotrusive movements. From protrusive movements the software of the device automatically calculated the left and the right sagittal condylar inclination values used for setting of the articulator. The mean sagittal condylar inclinationvalue was 41.0° (SD 10.5) for the right joint and 40.7° (SD 9.8) for the left joint. The maximum value was 65.0° for the right and 68.6° for the left joint, and the minimum value was 13.7° for the right and 21.7° for the left joint. The results of this study suggested the average articulator setting for sagittal condylar inclination for fully dentate adult subjects to be 40° in relation to Camper's plane. This is especially important for the articulators that are set up in relation to Camper's plane.
The aim of the study was to establish the subjective perception of dental medicine students' knowledge and skills in prosthodontics and to determine both how their perception changed during their ...study, by gaining clinical experience. Also, the aim was to investigate if there were any socio-demographic factors that influenced students' perception.
The research, based on an anonymous survey for dental medicine students was carried out at the School of Dental Medicine, University of Zagreb in 2015. YES/NO/DO NOT KNOW questions were used for assessment of students' knowledge, and a 50 mm visual analog scale was used for assessment of their abilities and skills. The Chi-square test, t-test for independent samples, analysis of variance and the Pearson's correlation coefficient were used for statistical data analysis.
Students' response (4th, 5th and 6th year of study) to the study amounted to 71,3%. The results showed that clinical experience and the number of correct answers from knowledge assessment increased with the year of study. Students with completed dental laboratory technician school took statistically significantly larger number of impressions and fabricated a significantly larger number of fixed restorations. Additionally, the results showed a significantly higher level of agreement with the statements about their perception of knowledge and skills.
Students' perceptions on learning positively correlated with the number of completed semesters in prosthodontics and the students' own clinical experience.
Gubitak zuba može uzrokovati gubitak pacijentove okluzijske, žvačne, estetske, fizionomske, fonetske i psihosocijalne funkcije. Najčešća metoda terapije potpuno bezubih pacijenata i onih s malim ...brojem preostalih zuba su potpune ili pokrovne proteze. Jedan od najvažnijih kliničkih i laboratorijskih postupaka u njihovoj izradi jest izrada funkcijskog otiska. Svrha ovog rada je prikazati postupke uzimanja funkcijskih otisaka u izradi potpunih i pokrovnih proteza korištenjem standardnih tehnika i materijala. Točan funkcijski otisak, zajedno s ostalim pravilno provedenim kliničkim i laboratorijskim postupcima, osigurava dobru retenciju i stabilizaciju proteze, što je preduvjet da se pacijentu vrate izgubljene funkcije.
Dentists and dental students can be exposed to the human immunodeficiency virus (HIV), hepatitis B virus (HBV), and hepatitis C virus (HCV) during routine work. The aims of this study were to assess ...a group of dental students’ knowledge about HIV, HBV, and HCV infections; assess their attitudes and risk perceptions about the treatment of patients with HIV, HBV, and HCV; and identify factors associated with their knowledge and willingness to treat these patients. An anonymous survey was administered to 534 predoctoral students at the School of Dental Medicine, University of Zagreb, Croatia. The response rate was 71.9 percent. Students’ knowledge increased with each year of study. Senior students (in their third, fourth, and fifth years) had more professional attitudes and were significantly more positive about dentists’ professional obligation to treat patients who are HIV‐positive than were junior students (in their first and second years; p=0.0002). Senior students also expressed significantly more willingness to treat intravenous drug users and patients with hepatitis (p=0.016 and p=0.033, respectively). Female students were significantly more convinced than male students that routine dental treatment carried a significant risk of HIV and hepatitis infection (p=0.025). These students’ knowledge negatively correlated with the lack of willingness to treat intravenous drug users and patients with hepatitis, and they expressed their willingness to receive further theoretical and practical education on this topic.
Aim Oral health of Croatian Army recruits has been researched. In2001, 505 19-year-old recruits in the barracks in Koprivnica wereclinically examined and asked about their health care habits.Methods ...The oral status of all teeth (except wisdom teeth) wasdescribed by the DMFT index (decayed, missing, and filled teeth)and compared with the FST index (filled and sound teeth). Thelevel of the recruits’ restored teeth was calculated by the formulaFTx100/DFT.Results The research showed the average DMFT index value of7.32. The average value of the FST index was 23.56, and 47.8%of the teeth were restored. A statistically significant difference accordingto domicile was determined in the DT, MT, FT and FSTindex. The subjects from rural environments had more teeth affectedby caries, and those from urban environments had more restoredteeth (66.59%). The health condition of the subjects fromurban environments is better (higher values of the FT index andslower cumulative distribution and statistical significance of theFST index).Conclusion The FST index is more adequate than the DMFT indexfor application in populations with a higher level of teeth affectedby caries. The research conducted contributes to the determinationof dental health of the Croatian Army recruits as well as to theorganisation of optimal preventive programs.
PDF
