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Öğe Intake of probiotics as an option for reducing oral and prosthetic microbiota: A clinical study(Elsevier Inc., 2024) Evirgen, Şehrazat; Kahraman, Emine Nur; Korcan, Safiye Elif; Yıldırım, Bengisu; Şimşek, Aysıla Tekeli; Aydın, BüşraStatement of problem: The accumulation of microorganisms on complete dentures has adverse effects on general health. Precautions should be taken to prevent colonization by these harmful pathogens, but whether an intake of probiotics effectively reduces microbiota is unclear. Purpose: The purpose of this clinical study was to examine the effectiveness of probiotics against the microbial colonization of dentures and the oral regions. Material and methods: Sixty-one edentulous participants with dentures were recruited, and samples were collected from the palate, cheek, tongue, and denture surface using sterile erasers before and after applying probiotics containing Lactobacillus acidophilus, Lactobacillus rhamnosus, Lactobacillus casei, and Bifidobacterium bifidum. The count of bacterial species in the original culture was calculated by multiplying the number of colonies by the dilution factor of cells per mL [log10 (CFU/mL)] for different media. Spread plating was used to colonize in vitro. A Wilcoxon test was used to compare the groups according to time reveal. Kruskal–Wallis and Mann–Whitney U tests were performed to compare the values in the various regions studied (α=.05). Results: A statistical difference in microbial count was found before and after probiotic intake (P<.05). For each medium, the microbial count values were statistically lower on the tongue, palate, dentures, and cheek after probiotic intake (P<.05), except for in malt medium on dentures (P>.05). Conclusions: Probiotics reduced the microbial count in the oral region and showed promising results for oral health and denture hygiene. Since the oral microbiota has among the highest levels of species diversity in the human body, further studies are needed. © 2024 Editorial Council for The Journal of Prosthetic DentistryÖğe Effect of coffee thermal cycling on the surface properties and stainability of additively manufactured denture base resins in different layer thicknesses(John Wiley and Sons Inc, 2025) Çakmak, Gülce; Asadolahi, Nura Watson; Schimmel, Martin; Molinero-Mourelle, Pedro; Akay, Canan; Dönmez, Mustafa Borga; Yılmaz, BurakPurpose: To compare the effect of coffee thermal cycling on surface roughness (Ra), Vickers microhardness (MH), and stainability of denture base resins additively manufactured in different layer thicknesses with those of subtractively manufactured denture base materials. Materials and Methods: Eighty disk-shaped specimens (Ø10×2 mm) were fabricated from two subtractively (Merz M-PM [SM-M] and G-CAM [SM-G]) and three additively (NextDent 3D+ [50 µm, AM-N-50; 100 µm, AM-N-100], FREEPRINT Denture [50 µm, AM-F-50; 100 µm, AM-F-100], and Denturetec [50 µm, AM-S-50; 100 µm, AM-S-100]) manufactured denture base materials (n = 10). Ra measurements were performed before and after polishing by using a non-contact optical profilometer, while MH values and color coordinates were measured after polishing. Specimens were then subjected to 5000 cycles of coffee thermal cycling, all measurements were repeated, and color differences (ΔE00) were calculated. A linear mixed effect model was used to analyze Ra and MH data, while one-way analysis of variance was used to analyze ΔE00 data (α = 0.05). Ra values were further evaluated according to a clinically acceptable threshold of 0.2 µm, while ΔE00 values were evaluated according to perceptibility (1.72 units) and acceptability (4.08 units) thresholds. The interaction between the material type and the time interval affected both Ra and MH (p ≤ 0.001). Tested materials had their highest Ra before polishing (p ≤ 0.029). Before polishing, AM-F-100 had the highest, and SM-M and SM-G had the lowest Ra (p < 0.001). After polishing and after coffee thermal cycling, SM-G mostly had lower Ra than those of other materials (p ≤ 0.036). SM-G mostly had higher MH than that of other materials before and after coffee thermal cycling (p ≤ 0.025). Coffee thermal cycling reduced the MH of SM-M and increased that of AM-S-100 (p ≤ 0.024). AM-N-100 had higher ΔE00 than AM-F, AM-S-100, and SM-G (p ≤ 0.009), while AM-F and SM-G had lower ΔE00 than AM-S-50 and AM-N-50 (p ≤ 0.024). Conclusions: Polishing reduced the surface roughness of all materials, whereas the effect of coffee thermal cycling was nonsignificant. Most of the tested materials had acceptable surface roughness after polishing and after coffee thermal cycling according to the reported threshold. Layer thickness only affected the microhardness of tested additively manufactured resins, which was material-dependent. Subtractively manufactured specimens mostly had high microhardness and that of nonreinforced subtractively manufactured resin decreased after coffee thermal cycling. When reported color thresholds are considered, all materials had acceptable color stability. © 2023 The Authors. Journal of Prosthodontics published by Wiley Periodicals LLC on behalf of American College of Prosthodontists.Öğe Effect of Polymerization Unit, Polishing, and Coffee Thermocycling on the Color and Translucency of Additively Manufactured Resins Used for Definitive Prostheses(Quintessence Publishing Co. Inc., 2024) Dönmez, Mustafa Borga; Çakmak, Gülce; Sabatini, Gabriela Panca; Kahveci, Çiğdem; Orğev, Ahmet; Yoon, Hyunğ-In; Yılmaz, BurakPurpose: To evaluate the effect of polymerization unit, polishing, and coffee thermocycling on the color and translucency of additively manufactured polyurethane-based resins with different viscosities. In addition, their color behavior was compared with the color of the shade tab throughout the fabrication steps and aging. Materials and Methods: Disk-shaped specimens (010 X 2 mm) were fabricated from polyurethane-based resins with different viscosities (Tera Harz TC-80DP and C&B permanent; n = 30 per material). Baseline color coordinates were measured after cleaning. The specimens in each resin group were divided into three subgroups (n = 10 per subgroup) to be polymerized with different polymerization units (Otoflash G171 [FLN], Wash and Cure 2.0 [CLED1], and P Cure [CLED2]), polished, and subjected to coffee thermocycling. Color coordinates were remeasured after each process. Color differences (ΔE00) and relative translucency parameter (RTP) values were calculated. Data were statistically analyzed (α =. 05). Results: Time points and polymerization units affected the ΔE00 for each material (P<. 049). ΔE00 of each polymerization unit pair had significant differences within and among different time points within each material (P <. 024). ΔE00 (when compared with the shade tab) and RTP were mostly affected by polymerization units and time points within both materials (P <. 042). Conclusions: Tested polymerization units, polishing, and coffee thermocycling affected the color difference and translucency of tested resins. Color differences ranged from moderately unacceptable to extremely unacceptable, and the differences in translucency values mostly ranged from perceptible to unacceptable, according to previous thresholds. In addition, tested resin-polymerization unit pairs had unacceptable color differences when compared to the shade tab. CLED1 may enable higher color stability for tested resins © (2024), (Quintessence Publishing Co. Inc.). All Rights Reserved.Öğe Mechanical properties of high- and low-fusing zirconia veneering ceramics fired on different trays and substrates(MDPI, 2024) Hoffmann, Moritz; Coldea, Andrea; Dönmez, Mustafa Borga; Meinen, JohnThis study aimed to evaluate the effect of ceramic type, firing tray, and firing substrate on the density, shrinkage, biaxial flexural strength, Martens' hardness, and elastic indentation modulus of zirconia veneering ceramics. Disk-shaped specimens were fabricated from a high-fusing (HFZ) and a low-fusing (STR) zirconia veneering ceramic. These specimens were then divided into 10 groups according to firing trays (round, small honeycomb-shaped, cordierite [RSC]; round, large honeycomb-shaped, aluminum oxide [RLA]; rectangular, plane, silicon nitride [RCPS]; round, plane, silicon nitride [RPS]; and rectangular, plane, calcium silicate [RCPC]) and firing substrates (firing cotton and platinum foil) used (n = 12). The density, shrinkage, biaxial flexural strength, Martens' hardness, and indentation modulus were measured, and analyzed with generalized linear model analysis (alpha = 0.05). The interaction between the ceramic type and firing substrate affected density (p < 0.001), and the other outcomes were affected by the interaction among all main factors (p <= 0.045). Higher density was observed with HFZ or platinum foil (p <= 0.007). RSC and RLA led to a higher density than RCPS within HFZ and led to the lowest density within STR (p <= 0.046). STR had a higher shrinkage (p < 0.001). RSC mostly led to a lower shrinkage of HFZ (p <= 0.045). The effect of ceramic type and firing substrates on the biaxial flexural strength, Martens' hardness, and indentation modulus was minimal while there was no clear trend on the effect of firing tray on these properties. Ceramic type, firing tray, and firing substrate affected the mechanical properties of the tested zirconia veneering ceramics. Firing the tested zirconia veneering ceramics over a round and small honeycomb-shaped cordierite firing tray with firing cotton mostly led to improved mechanical properties.Öğe Management of Compromised Spacing in the Esthetic Zone by Combining an Ultra-Thin Partial Ceramic Veneer and a Ceramic Implant Crown: A Case Report of a Multidisciplinary Approach and Technique Description(Quintessence Publishing Co. Inc., 2024) Fonseca, Manrique; Molinero-Mourelle, Pedro; Dönmez, Mustafa Borga; Abou-Ayash, Samir; Buser, Daniel; Sculean, Anton; Yılmaz, BurakDental implants are commonly used to replace missing single teeth. However, esthetic rehabilitation of an adjacent tooth may also be required due to diastemas, crowding, or existing large direct restorations to improve the final esthetic outcome. With the advancements in ceramics and bonding techniques, minimally invasive esthetic approaches have become viable for compromised spacing issues. This case report describes a dental technique for the esthetic rehabilitation of compromised anterior spacing with a customized zirconia implant abutment at a maxillary central incisor site and a partial ceramic veneer bonded to the adjacent central incisor. © 2024 by Quintessence Publishing Co Inc.Öğe Fracture resistance of additively or subtractively manufactured resin-based definitive crowns: Effect of restorative material, resin cement, and cyclic loading(Elsevier Inc., 2024) Çakmak, Gülce; Dönmez, Mustafa Borga; Molinero-Mourelle, Pedro; Kahveci, Çiğdem; Abou Ayash, Samir; Peutzfeldt, Anne; Yılmaz, BurakObjective: To evaluate how restorative material, resin cement, and cyclic loading affect the fracture resistance of resin-based crowns fabricated by using additive or subtractive manufacturing. Methods: A right first molar crown standard tessellation language (STL) file was used to fabricate 120 crowns from one subtractively manufactured polymer-infiltrated ceramic network (SM) and two additively manufactured resin composites (AM-B and AM-S) (N = 40). These crowns were randomly divided into 4 groups within each material according to the dual-polymerizing resin cement to be used (RX and PN) and the aging condition (n = 10). After cementation, the crowns without cyclic loading were subjected to fracture testing, while the others were first cyclically loaded (1.7 Hz, 1.2 million cycles, and 49-N load) and then subjected to fracture testing. Data were analyzed with generalized linear model analysis (α = .05). Results: Fracture resistance of the crowns was affected by material, resin cement, and cyclic loading (P ≤ .030). However, none of the interactions significantly affected fracture resistance of tested crowns (P ≥ .140). Among tested materials, SM had the highest fracture resistance, whereas AM-B had the lowest (P ≤ .025). RX led to higher fracture resistance, and cyclic loading decreased the fracture resistance (P ≤ .026). Significance: Tested materials can be considered reliable in terms of fracture resistance in short- or mid-term (5 years of intraoral simulation) when used for single molar crowns with 2 mm occlusal thickness. In the long term, polymer-infiltrated ceramic network crowns cemented with RelyX Universal may provide promising results and be less prone to complications considering higher fracture resistance values obtained. © 2024 The AuthorsÖğe INVESTIGATION OF THE EFFECT OF THE ONSET OF BRUXISM AS A RESULT OF EARLY ANTIDEPRESSANT USE(Medicinska Naklada Zagreb, 2024) Güldiken, İpek; Elbir, Begüm; Nalimov, Andrei; Delilbaşı, ÇağrıBackground: Among antidepressants, selective serotonin and noradrenaline reuptake inhibitors (SSRIs and SNRIs) have been widely used in the treatment of major depression and may induce sleep disorders and bruxism. In the present study, the effects of SSRIs and SNRIs on awake and sleep bruxism have been evaluated. Subjects and methods: A total of 125 patients who had been prescribed SSRIs or SNRIs for the treatment of major depression have been evaluated for bruxism. For the purpose of the study, data from the first week (T1) and the fourth week (T2) of antidepressant treatment have been considered. Results: In conclusion, in the early period, the presence of bruxism has not been observed to be significantly influenced by the use of antidepressants. It has been determined that sleep bruxism increased in the fourth week only in males who were using antidepressants (p = 0.015; p < 0.05). An increase in the presence of sleep bruxism due to specific SSRIs and SNRIs has been determined in the fourth week of drug use. Paroxetine in the SSRI group and duloxetine in the SNRI group have been found to cause an increase in sleep bruxism (p = 0.013; p < 0.05). Other active substances have not been found to affect sleep or awake bruxism significantly. Conclusion: The present study has shown that although some antidepressants increase bruxism in the early period of drug use, the effects of similar drugs on sleep or awake bruxism need to be evaluated in detail in long-term studies. © Medicinska naklada.Öğe Fracture resistance of additively or subtractively manufactured resin-based definitive crowns: Effect of restorative material, resin cement, and cyclic loading(Elsevier, 2024) Çakmak, Gülce; Dönmez, Mustafa Borga; Molinero-Mourelle, Pedro; Kahveci, Çiğdem; Abou-Ayash, Samir; Peutzfeldt, Anne; Yılmaz, BurakObjective: To evaluate how restorative material, resin cement, and cyclic loading affect the fracture resistance of resin -based crowns fabricated by using additive or subtractive manufacturing. Methods: A right first molar crown standard tessellation language (STL) file was used to fabricate 120 crowns from one subtractively manufactured polymerinfiltrated ceramic network (SM) and two additively manufactured resin composites (AM -B and AM -S) (N = 40). These crowns were randomly divided into 4 groups within each material according to the dual -polymerizing resin cement to be used (RX and PN) and the aging condition (n = 10). After cementation, the crowns without cyclic loading were subjected to fracture testing, while the others were first cyclically loaded (1.7 Hz, 1.2 million cycles, and 49-N load) and then subjected to fracture testing. Data were analyzed with generalized linear model analysis ( alpha = .05). Results: Fracture resistance of the crowns was affected by material, resin cement, and cyclic loading ( P <= .030). However, none of the interactions significantly affected fracture resistance of tested crowns ( P >= .140). Among tested materials, SM had the highest fracture resistance, whereas AM -B had the lowest ( P <= .025). RX led to higher fracture resistance, and cyclic loading decreased the fracture resistance ( P <= .026). Significance: Tested materials can be considered reliable in terms of fracture resistance in short- or mid-term (5 years of intraoral simulation) when used for single molar crowns with 2 mm occlusal thickness. In the long term, polymer -infiltrated ceramic network crowns cemented with RelyX Universal may provide promising results and be less prone to complications considering higher fracture resistance values obtained.Öğe Positional accuracy of a single implant analog in additively manufactured casts in biobased model resin(Elsevier, 2024) Diken Türksayar, Almira Ada; Demirel, Münir; Petersmann, Sandra; Spintzyk, Sebastian; Dönmez, Mustafa BorgaObjectives: To evaluate the positional accuracy of implant analogs in biobased model resin by comparing them to that of implant analogs in model resin casts and conventional analogs in dental stone casts. Methods: Polyvinylsiloxane impressions of a partially edentulous mandibular model with a single implant were made and poured in type IV dental stone. The same model was also digitized with an intraoral scanner and additively manufactured implant casts were fabricated in biobased model resin (FotoDent biobased model) and model resin (FotoDent model 2 beige -opaque) ( n = 8). All casts and the model were digitized with a laboratory scanner, and the scan files were imported into a 3 -dimensional analysis software (Geomagic Control X). The linear deviations of 2 standardized points on the scan body used during digitization were automatically calculated on x-, y-, and z-axes. Average deviations were used to define precision, and 1 -way analysis of variance and Tukey HSD tests were used for statistical analyses ( alpha = 0.05). Results: Biobased model resin led to higher deviations than dental stone (all axes, P <= 0.031) and model resin (yaxis, P = 0.015). Biobased model resin resulted in the lowest precision of implant analog position ( P <= 0.049). The difference in the positional accuracy of implant analogs of model resin and stone casts was nonsignificant ( P >= 0.196). Conclusions: Implant analogs in biobased model resin casts mostly had lower positional accuracy, whereas those in model resin and stone casts had similar positional accuracy. Regardless of the material, analogs deviated more towards mesial, while buccal deviations in additively manufactured casts and lingual deviations in stone casts were more prominent.Öğe Modelling Intra-Sinus Fluid Movements and Drainage Through Computational Fluid Dynamics Before and After Maxillary Sinus Augmentation: A Simulation-Based Pilot Study(Multidisciplinary Digital Publishing Institute (MDPI), 2025) Güldiken Sarıkaya, İpek Necla; Tekin, Alperen; Suda, Fatih; Çukurova Yılmaz, Zeynep Gülen; Özcan, MutluObjectives: Sinus lifting, a procedure to augment bone in the maxilla, may cause complications such as sinusitis due to impaired drainage. This study aimed to assess how sinus lifting impacts airflow in the sinus cavity, which is essential for patients undergoing dental implants. Using computational fluid dynamics (CFD), this research analyzed airflow changes after sinus floor elevation, offering insights into the aerodynamic consequences of the procedure. Methods: Digital modeling and CFD analysis were performed using patient cone-beam computed tomography data. Three different sinus elevation scenarios, each with varying implant heights, were simulated. Airflow simulations were conducted to assess how reshaping the sinus cavity affects aerodynamics and airflow dynamics. Nasal resistance, calculated through pressure drops and flow rates, and wall shear stress, indicating potential mucosal damage, were evaluated. Results: Although some airflow changes occurred post-surgery, the implants primarily affected the front and rear of the elevated area, with little impact being seen on air entry points. Conclusions: Maxillary sinus lifting for dental implant placement may impair sinus drainage, especially at higher elevations, increasing the risk of mucosal damage due to intensified airflows in the reduced sinus volume. A more uniform, simplified intra-sinus structure may enhance fluid dynamics and reduce complications. © 2024 by the authors.Öğe Fatigue behavior of implant-supported cantilevered prostheses in recently introduced CAD-CAM polymers: An in vitro study(Elsevier Inc., 2024) Dönmez, Mustafa Borga; Çakmak, Gülce; Güven, Mehmet Esad; Dede, Doğu Ömür; Abou Ayash, Samir; Yılmaz, BurakStatement of problem: Cantilevered complete arch implant-supported prostheses are commonly fabricated from zirconia and more recently from strength gradient zirconia. Different polymer-based materials indicated for definitive fixed prostheses that could be used with additive or subtractive manufacturing have also been marketed recently. However, knowledge on the long-term fatigue behavior of cantilevered implant-supported prostheses made from these polymer-based materials and strength gradient zirconia is lacking. Purpose: The purpose of this in vitro study was to evaluate the fatigue behavior of implant-supported cantilevered prostheses of recently introduced computer-aided design and computer-aided manufacturing polymers and zirconia. Material and methods: A master standard tessellation language file of a 9×11×20-mm specimen with a titanium base (Ti-base) space that represented an implant-supported cantilevered prosthesis was used to fabricate specimens from additively manufactured interim resin (AM), polymethyl methacrylate (SM-PM), nanographene-reinforced polymethyl methacrylate (SM-GR), high-impact polymer composite resin (SM-CR), and strength gradient zirconia (SM-ZR) (n=10). Each specimen was prepared by following the respective manufacturer's recommendations, and Ti-base abutments were cemented with an autopolymerizing luting composite resin. After cementation, the specimens were mounted in a mastication simulator and subjected to 1.2 million loading cycles under 100 N at 1.5 Hz; surviving specimens were subjected to another 1.2 million loading cycles under 200 N at 1.5 Hz. The load was applied to the cantilever extension, 12-mm from the clamp of the mastication simulator. The Kaplan–Meier survival analysis and Cox proportional hazards model were used to evaluate the data (α=.05). Results: Significant differences in survival rate and hazard ratio were observed among materials (P<.001). Among tested materials, SM-ZR had the highest and AM had the lowest survival rate (P≤.031). All materials had a significantly higher hazard ratio than SM-ZR (P≤.011) in the increasing order of SM-GR, SM-PM, SM-CR, and AM. Conclusions: SM-ZR had the highest survival rate with no failed specimens. Even though most of the tested polymer-based materials failed during cyclic loading, these failures were commonly observed during the second 1.2 million loading cycles with 200 N. All materials had a higher hazard ratio than SM-ZR. © 2024 The AuthorsÖğe Effect of barium silicate on mechanical properties, transmittance, and protein adsorption of resin for additive manufacturing containing zwitterionic polymer(Elsevier Inc., 2024) Dönmez, Mustafa Borga; Kim, Hyun-Tae; Lee, Yun-Hee; Jo, Ye-Hyeon; Yoon, Hyung-In; Yılmaz, BurakStatement of problem: Studies on the effect of barium silicate on the material properties of additively manufactured (AM) resins containing 2-methacryloyloxyethyl phosphorylcholine (MPC) for dental applications are lacking. Purpose: The purpose of this in vitro study was to evaluate the mechanical properties, transmittance, and protein adsorption of MPC-containing AM resin incorporated with different barium silicate contents and to compare these findings with those of a commercially available unfilled AM resin marketed for definitive restorations. Material and methods: Resins incorporating 6 wt% MPC and 4 different concentrations of barium silicate (10 wt%, MB10; 20 wt%, MB20; 30 wt%, MB30; and 40 wt%, MB40) were prepared. An MPC-containing resin with no filler was also prepared (0 wt%, MBN). Surface roughness (n=15), Vickers hardness (n=15), flexural strength and modulus (n=15), fracture toughness (n=15), transmittance (n=15), and protein adsorption (n=3) of the filled resin specimens were measured and compared with those of commercially available unfilled resin specimens. All data were analyzed using the Kruskal–Wallis and Dunn tests (α=.05). Results: All experimental resins had higher surface roughness than the unfilled resin (P≤.048). MB40 had higher hardness, flexural strength, flexural modulus, and fracture toughness than most other groups (P≤.047). MB10 had higher transmittance than most other groups (P≤.012). All experimental resins had lower protein adsorption than the unfilled resin, regardless of the barium silicate content (P≤.023). Conclusions: The experimental resin containing 6 wt% MPC and 40 wt% barium silicate showed better mechanical properties and lower protein adsorption than the resin with no MPC or ceramic fillers. Transmittance decreased with the increase of barium silicate in the resins. © 2024 Editorial Council for The Journal of Prosthetic DentistryÖğe Effect of femtosecond laser induced surface patterns on the flexural strength of monolithic zirconia(Wiley, 2024) Okutan, Yener; Gündoğdu, Yasemin; Dönmez, Mustafa Borga; Şeker, Hüseyin; Kılıç, Hamdi ŞükürTo investigate how patterns generated by femtosecond (fs) laser and femtosecond laser power affect the surface roughness (Ra) and biaxial flexural strength (BFS) of monolithic zirconia. Eighty disk-shaped zirconia specimens were divided into eight subgroups (n = 10): Control (C), airborne-particle abrasion (APA), 400 mW fs laser (spiral [SP(400)], square [SQ((400))], circular [CI(400)]), and 700 mW fs laser ([SP(700)], [SQ((700))], [CI(700)]). Ra values were calculated by using a surface profilometer. One additional specimen per group was analyzed with scanning electron microscopy and x-ray diffractometry. BFS values were obtained by using the piston-on-3-ball test. One-way ANOVA and either Tukey's HSD (BFS) or Tamhane's T2 (Ra) tests were used to evaluate data (alpha = 0.05). Regardless of the pattern and power, fs laser groups had higher Ra than C and APA, while SP groups had lower Ra than CI and SQ groups (p <= 0.004). For each pattern, Ra increased with higher laser power (p < 0.001), while the laser power did not affect the BFS (p >= 0.793). CI and SQ groups had lower BFS than the other groups (p <= 0.040), whereas SP groups had similar BFS to C and APA (p >= 0.430). Fs laser microstructuring with spiral surface pattern increased the Ra without jeopardizing the BFS of zirconia. Thus, this treatment might be an option to roughen tested zirconia.Öğe Surface roughness, optical properties, and microhardness of additively and subtractively manufactured CAD-CAM materials after brushing and coffee thermal cycling(John Wiley and Sons Inc, 2025) Çakmak, Gülce; Dönmez, Mustafa Borga; de Paula, Marcella Silva; Akay, Canan; Fonseca, Manrique; Kahveci, Çiğdem; Abou-Ayash, Samir; Yılmaz, BurakPurpose: To evaluate the surface roughness, optical properties, and microhardness of additively or subtractively manufactured CAD-CAM materials after simulated brushing and coffee thermal cycling. Material and methods: Two additively manufactured resins (Crowntec, CT and VarseoSmile Crown Plus, VS) and 3 subtractively manufactured materials (a reinforced composite (Brilliant Crios, BC), a polymer-infiltrated ceramic network (Enamic, VE), and a feldspathic ceramic (Mark II, VM)) were used to fabricate disk-shaped specimens (Ø10×1-mm) (n = 10). Surface roughness, Vickers microhardness, and color coordinates were measured after polishing, while surface roughness was also measured before polishing. Specimens were then subjected to 25000 cycles of brushing and 10000 cycles of coffee thermal cycling, and measurements were repeated after each time interval. Color difference (ΔE00) and relative translucency parameter (RTP) were calculated. Robust analysis of variance test was used to evaluate surface roughness, ΔE00, and RTP data, while generalized linear model analysis was used for microhardness data (α = 0.05). Results: Material type and time interval interaction affected tested parameters (p ≤ 0.002). In addition, material type affected all parameters (p < 0.001) other than surface roughness (p = 0.051), and time interval affected surface roughness and microhardness values (p < 0.001). Tested materials mostly had their highest surface roughness before polishing (p ≤ 0.026); however, there was no clear trend regarding the roughness of materials within different time intervals along with ΔE00 and RTP values within materials or time intervals. VS and CT had the lowest microhardness regardless of the time interval, while the remaining materials were listed as VM, VE, and BC in decreasing order (p < 0.001). Coffee thermal cycling only reduced the microhardness of VM (p < 0.001). Conclusions: Tested additively manufactured resins can be considered more susceptible to simulated brushing and coffee thermal cycling than the other materials, given the fact that their surface roughness and ΔE00 values were higher than previously reported acceptability thresholds and because they had the lowest microhardness after all procedures were complete. © 2023 The Authors. Journal of Prosthodontics published by Wiley Periodicals LLC on behalf of American College of Prosthodontists.Öğe Dimensional stability of additively manufactured dentate maxillary diagnostic casts in biobased model resin(MDPI, 2024) Demirel, Münir; Türksayar, Almira Ada Diken; Petersmann, Sandra; Spintzyk, Sebastian; Dönmez, Mustafa BorgaThis study aimed to evaluate the dimensional stability of maxillary diagnostic casts fabricated from a biobased model resin, which consists of 50% renewable raw materials for sustainable production, a model resin, and stone, over one month. A master maxillary stone cast was digitized with a laboratory scanner to generate a reference file. This master cast was also scanned with an intraoral scanner to additively manufacture casts with a biobased model resin (BAM) and a model resin (AM). Polyvinylsiloxane impressions of the master cast were also made and poured in type III stone (CV) (n = 8). The same laboratory scanner was used to digitize each model one day (T0), 1 week (T1), 2 weeks (T2), 3 weeks (T3), and 4 weeks (T4) after fabrication. Deviations from the reference file were calculated with an analysis software and analyzed with generalized linear model analysis (alpha = 0.05). The interaction between the material and the time point affected measured deviations (p < 0.001). Regardless of the time point, CV had the lowest and AM had the highest deviations (p < 0.001). BAM mostly had lower deviations at T0 and mostly had higher deviations at T4 (p <= 0.011). AM had the highest deviations at T4 and then at T3, whereas it had the lowest deviations at T0 (p <= 0.002). The measured deviations of CV increased after each time point (p < 0.001). BAM casts had deviations within the previously reported clinically acceptable thresholds over one month and had acceptable dimensional stability. Therefore, tested biobased resin may be a viable alternative for the sustainable manufacturing of maxillary diagnostic casts that are to be used clinically.Öğe Development and performance evaluation of a novel scintillation-based active shielding gamma probe(Springer Science and Business Media Deutschland GmbH, 2024) Kolcu, Onur Buğra; Yetkin, Taylan; Zengin, A. T.; İren, Emre; Günay, E. C.The gamma probe is a commonly used detector for localizing sentinel lymph nodes after the injection of radiopharmaceuticals. In recent years, studies have focused on improving the features of gamma probes to achieve more consistent localization of the radiotracer uptake. As part of this effort, a novel gamma probe prototype based on an active shielding was developed, and its characteristics, including sensitivity, resolution and shielding effectiveness, were determined. The prototype integrates trapezoidal-shaped bismuth germanate (BGO) array coupled with a silicon photomultiplier (SiPM) array, accompanied by dedicated electronics and software for stand alone usage. We conducted a thorough characterization, validating experimental observations through Monte Carlo simulations using the GEANT4 simulation package. In scattering environment, with a probe-source distance of 30 mm, the experimental results show that the detector sensitivity is 120±5 cps/MBq, and the spatial and angular resolutions, in terms of full width at half maximum (FWHM), are 44.8±1.3 mm and 87.3±1.5∘, respectively. The shielding effectiveness of the probe was determined to be greater than 95%. The prototype with active shielding was found to have comparable performance to conventional gamma probes. © Australasian College of Physical Scientists and Engineers in Medicine 2024.Öğe Clinical and radiographic evaluation of two different apexification protocols in traumatized immature permanent incisors(Turkish Association of Trauma and Emergency Surgery, 2025) Koyuncuoğlu, Gülhan; Eren, GamzeBACKGROUND: Dental trauma can cause damage to the pulp tissue in immature teeth. Revascularization therapy is a possible option in the treatment of non-vital, immature permanent teeth with a history of trauma. The aim of this prospective study was to evalu-ate the radiographic and clinical results of immature teeth with a history of trauma treated by regenerative endodontic procedures and mineral trioxide aggregate apexification techniques. METHODS: Forty-one patients aged between 7 and 12 years with traumatized immature permanent maxillary incisors were included in the study. These patients were divided into two groups: those who had previously received endodontic treatment and those who had not. Twenty-four patients who applied directly to the university clinic and had not received endodontic treatment before were included in the regenerative endodontic protocol group (Group 1). Seventeen patients who had previously undergone endodontic intervention on their relevant teeth were included in the mineral trioxide aggregate apexification group (Group 2). The patients were followed for a period of 24 months. Clinical success rates were evaluated, and pre-treatment and control radiographs were analyzed to calculate the percentage increase in root dentin width and root length. RESULTS: After 24 months of follow-up, positive periapical healing was detected in the radiographic findings in the majority of cases. In Group 1, a limited increase in root length and root dentin width was observed, while a narrowing in the apical opening was evident. The radiographic evaluation of two of the cases, which could be accessed 11 years later, emphasized the importance of long-term follow-up in assessing the effectiveness of the chosen methods. CONCLUSION: The revascularization method is a treatment option that has positive results in terms of root development in teeth with necrotic pulp as a result of trauma. © 2025, Turkish Association of Trauma and Emergency Surgery. All rights reserved.Öğe Awareness and knowledge of halitosis among students at two different dental universities in Turkey: a cross-sectional survey(2025) Kahraman, Emine Nur; Erensoy, Şehrazat; Dikilitaş, Ahu; Gülşahı, Ayşe; Aydın, Esra Özge; Ateş, Funda Seher ÖzalpBackground Halitosis, or bad breath, significantly affects social and psychological well-being and is often caused by intraoral factors. Dentists play a key role in the diagnosis and treatment of halitosis, but inadequate education may lead to ineffective patient care. This study examines the levels of knowledge and awareness of halitosis among undergraduate dental students. Methods This study employed a cross-sectional design and used an online questionnaire that was developed via Google Forms. The questionnaire was distributed to a convenience sample of 250 undergraduate students from two different dentistry faculties who had completed their clinical internships. All the statistical analyses were performed using SPSS for Windows 11.5 (SPSS Inc., Chicago, IL, USA). Responses to the questionnaire were compared between groups using the Pearson chi-square test or Fisher's exact test. The correct answer scores were compared between groups via the Mann-Whitney U test. Results There was a significant difference in the degree of attention devoted to halitosis between X University and Y University (p < 0.05). When asked, "Have you ever treated patients with halitosis? ", 28.5% of fourth-year students and 60.5% of fifth-year students answered affirmatively, indicating a statistically significant difference (p < 0.001). There was no significant difference in the number of correct answers between fourth- and fifth-year students (U = 7714.00, p = 0.886). There was a significant difference in the number of correct answers between the universities (U = 5817.50, p = 0.001). The number of correct answers of X University students was slightly higher than that of Y University students. Conclusions These results support the importance of developing training programs to improve dentists' self-confidence, social skills, and communication skills, thereby enhancing the diagnosis and treatment of halitosis. A manual for the diagnosis and treatment of halitosis could be helpful for improving dentists' attitudes and behaviours and for promoting optimal oral health.Öğe Cameo and intaglio surface stability and variability of additively, subtractively, and conventionally manufactured occlusal devices after long-term storage(Elsevier, 2024) Orgev, Ahmet; Dönmez, Mustafa Borga; Almogbel, Lolowh; Çakmak, Gülce; Marques, Vinicius Rizzo; Kahveci, Çiğdem; Yılmaz, BurakStatement of problem: Additive and subtractive manufacturing have become alternative technologies for fabricating occlusal devices. However, knowledge of the long-term stability of occlusal devices fabricated using these recent technologies is limited. Purpose: The purpose of this in vitro study was to evaluate the cameo and intaglio surface stability and variability of additively, subtractively, and conventionally manufactured occlusal devices after 18 months of storage. Material and methods: A standard tessellation language (STL) file of a dentate maxillary typodont was used to design a master occlusal device. The STL file of this design was used to fabricate occlusal devices additively either with a digital light processing (AM-1) or a continuous liquid interface production (AM-2) printer, subtractively with 2 different 5-axis milling units (SM-1 and SM-2), and conventionally (TM-HP) (n=10). STL files of each device's cameo and intaglio surfaces were generated using a laboratory scanner after fabrication and after 18 months of storage in a moist environment. These generated files were imported into an analysis software program (Geomagic Control X) to analyze the dimensional stability of tested devices by using the root mean square method. The average deviation values defined the variability of measured changes over time. Cameo and intaglio surface deviations were analyzed using the Kruskal-Wallis and Dunn tests, while the variability of measured deviations was analyzed with 1-way analysis of variance and the Tukey HSD tests (α=.05). Results: Significant differences were observed among tested devices when the intaglio surface deviations and the cameo surface variability were considered (P<.001). SM-2 had significantly higher intaglio surface deviations than AM-1, SM-1, and AM-2 (P≤.036). Among the test groups, AM-1 had the greatest cameo surface variability (P≤.004). Conclusions: SM-2 resulted in lower intaglio surface stability than the additive and the other subtractive manufacturing technologies, while AM-1 led to the highest cameo surface variability among the test groups.Öğe Investigation of COVID-19 Fear and Burnout in General Surgery Assistants(Oğuz Karabay, 16 Haziran 2024) Mollaoglu, Murat Can; Karadayı, KürşatObjective: The aim of the study is to examine the burnout of general surgery assistants due to fear of Covid-19. Materials and Methods: The study, which had a descriptive and cross-sectional design, was conducted with 103 general surgery residents. Data; It was obtained with the Personal Information Form, Covid-19 Fear Scale and Maslach Burnout Scale. The data were evaluated in the SPSS program. Results: The average score of the residents on the Fear of Covid-19 Scale was found to be above the middle score. While depersonalization and emotional exhaustion, which are the sub-dimensions of the Maslach Burnout Scale, were experienced at moderate levels, it was determined that there was a significant decrease in the personal accomplishment dimension. It has been determined that assistants with a high fear of Covid-19 experience high levels of emotional exhaustion and high levels of depersonalization, as well as a feeling of decreased personal accomplishment. Conclusion: It is important to consider general surgery assistants, who are at high risk of contracting the Covid-19 virus, as risky groups during epidemic periods, and to implement necessary protective measures and crisis management policies including psychological support in reducing burnout syndrome.
