Duygu Karakis

Resin cementation of zirconia ceramics with different bonding agents

The aim of this study was to evaluate the effects of sandblasting and different chemical bonding agents on shear bond strength of zirconia and conventional resin cement. In this study, 35 zirconia specimens were treated as follows: Group I: control; Group II: sandblasting; Group III: sandblasting + Monobond S; Group IV: sandblasting + Monobond Plus; Group V: sandblasting + Z-Prime Plus. The specimens in each group were bonded with conventional composite resin cement Variolink II. After cementation, specimens were stored in distilled water (at 37 °C) for 24 h and shear test was performed. The highest shear bond strength values were observed in Groups IV and V. The lowest shear bond strength values were observed in Group I. Using 10-methacryloyloxy-decyl dihydrogenphosphate monomer-containing priming agents, e.g. Monobond Plus and Z-PRIME Plus, combined with sandblasting can be an effective method for resin bonding of zirconia restorations.

The craniofacial morphology and maximum bite force in sleep bruxism patients with signs and symptoms of temporomandibular disorders

Abstract Objectives: The purpose of the present study was to compare craniofacial morphology and bite force of bruxist patients with signs and symptoms of temporomandibular disorders. Method: Fourteen subjects with sleep bruxism and 14 healthy subjects participated. The signs and symptoms of the temporomandibular disorders were identified according to the Craniomandibular Index (CMI). Maximum bite force was measured using strain-gage transducers. Lateral cephalometric films were taken, and linear and angular measurements were performed. Results: Bite force between bruxist and non-bruxist females was not significant, whereas males with bruxism revealed higher bite forces. None of the linear and angular measurements differed significantly between bruxist and non-bruxist males. However, higher mandibular corpus length and anterior cranial base length, and lower gonial angle were observed in bruxist females compared to non-bruxist females. Negative correlation between bite force and CMI values was found in both genders. Discussion: Bruxist females had higher CMI values than bruxist males, which could lead to relatively lower bite forces.

The bite force and craniofacial morphology in patients with acromegaly: a pilot study.

Objectives: Acromegaly is a metabolic disorder caused by increased growth hormone secretion. As a consequence of acromegaly some typical craniofacial morphology changes appear. This pilot study was conducted to compare the bite force and the characteristic size and shape of the craniofacial components of acromegalic patients with the healthy Turkish individuals. In additon, the correlations between bite force and craniofacial morphology of patients with acromegaly and control individuals were evaluated. Study Design: The maximum bite force of the participants was recorded with strain-gage transducer. Lateral x-ray scans were made under standard conditions, in centric occlusion. On cephalograms, the linear and angular measurements was performed. Results: Patients with acromegaly showed increased anterior and posterior total face height, ramus length, width of frontal sinuse, gonial angle and a negative difference between maxillary and mandibular protrusions. In addition, females with acromegaly showed larger lower anterior face height and sella turcica, decreased facial angle, increased mandibular plane angle. The cephalometric measurements, except one did not showed correlation with the bite force in acromegalic patients. In control group, significant correlations were observed between anterior total face height and anterior lower face height, mandibular plane angle and gonial angle. Conclusions: The greater changes were observed in the mandible. The maximum bite force of patients with acromegaly showed no difference from healthy individuals. The non-significant difference of bite force between healthy participants and acromegalic patients provide important information for dental treatment and prosthetic rehabilitation of acromegalic patients. Key words:Acromegaly, bite force, cephalometric analysis, mandibular prognathism.

Evaluation of the effect of two different occlusal splints on maximum occlusal force in patients with sleep bruxism: a pilot study

PURPOSE The occlusal splint has been used for many years as an effective treatment of sleep bruxism. Several methods have been used to evaluate efficiency of the occlusal splints. However, the effect of the occlusal splints on occlusal force has not been clarified sufficiently. The purpose of this study was to evaluate the effect of occlusal splints on maximum occlusal force in patients with sleep bruxism and compare two type of splints that are Bruxogard-soft splint and canine protected hard stabilization splint. MATERIALS AND METHODS Twelve students with sleep bruxism were participated in the present study. All participants used two different occlusal splints during sleep for 6 weeks. Maximum occlusal force was measured with two miniature strain-gage transducers before, 3 and 6 weeks after insertion of occlusal splints. Clinical examination of temporomandibular disorders was performed for all individuals according to the Craniomandibular Index (CMI) before and 6 weeks after the insertion of splints. The changes in mean occlusal force before, 3 and 6 weeks after insertion of both splints were analysed with paired sample t-test. The Wilcoxon test was used for the comparison of the CMI values before and 6 weeks after the insertion of splints. RESULTS Participants using stabilization splints showed no statistically significant changes in occlusal force before, 3, and 6 weeks after insertion of splint (P>.05) and participants using Bruxogard-soft splint had statistically significant decreased occlusal force 6 weeks after insertion of splint (P<.05). There was statistically significant improvement in the CMI value of the participants in both of the splint groups (P<.05). CONCLUSION Participants who used Bruxogard-soft splint showed decreases in occlusal force 6 weeks after insertion of splint. The use of both splints led to a significant reduction in the clinical symptoms.

Effectiveness of disinfectants on the adherence of Candida albicans to denture base resins with different surface textures

The aim of the present study was to compare the effects of some disinfectants, including ethanol extract of propolis (EEP), on the adhesion of Candida albicans to denture base resins. Seventy-two acrylic resin samples were prepared, half of which was polished and the other half was roughened. C. albicans strain ATCC 10231 was incubated on Sabouraud dextrose agar (SDA) at 37°C for 48 h. The adhesion period was completed by keeping the cells in this suspension for 90 min at 37°C. Specimens were then immersed in the following solutions: 1%, 2%, and 5% sodium hypochlorite; 4% chlorhexidine gluconate; and 10% EEP. Quantification of the antifungal activity of the chemical solutions was performed using the colorimetric MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assay test. One-way ANOVA and post-hoc Tukey tests were performed to evaluate the effectiveness of chemical agents. Polished and roughened surfaces were compared using independent sample t-test. The mean surface roughness value was 0.35 (±0.04) µm for the polished group and 1.2 (±0.2) µm for the roughened group. The contact angles of both surfaces showed statistically significant difference, and 10% EEP solution exhibited significantly less removal of adherent viable C. albicans cells in both groups. All forms of sodium hypochlorite solutions yielded higher efficiency than 4% chlorhexidine gluconate and EEP solutions (P < 0.05). (J Oral Sci 58, 431-437, 2016).

The evaluation of maximum bite force in the occlusal rehabilitation of patient with Angle Class III malocclusion: a case report

The case report describes the occlusal rehabilitation of a male patient with Angle Class III malocclusion and its effect on maximum bite force. The main complaints of patient were masticatory difficulty and poor esthetic. The patients expectations from the treatment were a good esthetic and function with a less invasive and relatively promptly way. Therefore, increasing of the occlusal vertical dimension (OVD) and then restoring the maxillary and mandibular teeth was chosen by the patient among the treatment options. At the beginning of treatment maximum bite force of patient was measured. Then an occlusal splint was provided to evaluate the adaptation of the patient to the altered OVD. Full mouth rehabilitation with metal ceramic restorations was made. After the completion of full mouth restoration, bite force measurement was repeated and patient exhibited increased maximum bite force. Full mouth restorative treatment in a patient with Class III malocclusion could be an effective treatment approach to resolve esthetic concern and to improve masticatory function related to maximum bite force.

In Vitro Cytotoxicity of Maxillofacial Silicone Elastomers: Effect of Nano-particles

PURPOSE Silicone elastomers are generally used for maxillofacial extraoral prostheses. The purpose of this in vitro study was to evaluate the cytotoxicity of different kinds of nanoparticles added to two types of maxillofacial elastomers. MATERIALS AND METHODS A-2000 and A-2006 silicone elastomers were used. The silicone specimens were divided into eight groups according to the presence of additional nanoparticles (n = 18). The following represents the groups in the study: Group A: A-2000 silicone (control group); Group B: A-2006 silicone (control group); Group C: A-2000 silicone and the addition of titanium dioxide (TiO2 ); Group D: A-2006 silicone and the addition of TiO2 ; Group E: A-2000 silicone and the addition of fumed silica; Group F: A-2006 silicone and the addition of fumed silica; Group G: A-2000 silicone and the addition of silaned silica; Group H: A-2006 silicone and the addition of silaned silica. A paired sample t-test was used to analyze the cytotoxicity of each group after 24, 48, and 72 hours. RESULTS Based on the results of the 24-hour analysis, the biocompatibility values of the (A-2006) fumed silica group were higher than those of the control groups. There was no statistically significant difference in A-2006 and A-2000 groups. The cytotoxicity values of the control groups and TiO2 (A-2000 silicone) elastomer groups increased at all test times; however, the cytotoxicity values of the TiO2 (A-2006), fumed silica (A-2006), silaned silica (A-2006), fumed silica (A-2000), and silaned silica (A-2000) groups increased significantly only from 24 to 48 hours. CONCLUSION Nanoparticles of TiO2 , fumed silica, and silaned silica added to a commercial silicone-based elastomer used for fabrication of maxillofacial prostheses are nontoxic.

Effect of self and dual-curing on degree of conversion and crosslink density of dual-cure core build-up materials

PURPOSE Dual-cure core build-up resins have been developed to take advantages of both self and light-cured resin. The aim of present study was to determine the polymerization characteristics of self and dual-cured modes of dual-cure core build-up composites evaluating degree of conversion (DC) and crosslink density by measurement of glass-transition temperature (Tg) and hardness decrease in ethanol. METHODS Clearfil Dc Core Automix (CLF) and Grandio Core Dc (GR) core build-up resins were selected. Twelve specimens for both composites were polymerized using quartz-halogen-tungsten light curing unit (QTH) and 12 specimens polymerized chemically. DC was determined by ATR-FTIR spectroscopy. TG/DTA analysis was performed to determine Tg. Microhardness value of specimens was determined by Vickers-tester before and after specimens stored in absolute ethanol for 24h. RESULTS One-way ANOVA showed no different DC values between dual and self-cured mode of GR and dual-cured CLF composites had higher DC than self-cured mode. Tg and percentage of softening in ethanol values of GR and CLF revealed significant difference between self and dual-cured mode. CONCLUSIONS In comparison of GR and CLF, DC showed no statistical difference in both curing modes. However, dual and self-cured GR has statistically higher Tg values and lower percentage of softening in ethanol than CLF. Polymerization characteristics of dual-cure core build-up composites have superiority in dual-cured mode than self-cured.

Effect of Chemical Disinfectants on Candida albicans Biofilm Formation on Poly (Methyl Methacrylate) Resin Surfaces: A Scanning Electron Microscope Study

Objective: The purpose of this study was to understand the complexities of Candida albicans biofilm formation and to evaluate the effectiveness of most used antimicrobial agents. Materials and Methods: About 24 acrylic resin specimens (2 mm thickness, 10 mm diameter) were prepared. The contact angle and surface roughness of all specimens were measured. C. albicans ATCC10231 was incubated in Sabouraud dextrose agar (SDA) at 37°C for 24 h. Subsequently, SDA was incubated at 37°C for 48 h. Specimens were immersed to 1% and 2% sodium hypochlorite and phosphate-buffered saline for 10 min and 4% chlorhexidine gluconate for 5 min. The efficiency of chemical disinfectants in removing C. albicans biofilm was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium-bromide assay test. After application of chemical disinfectant, acrylic resin specimens were examined using scanning electron microscopy (SEM). The evaluation of the efficiency of chemical disinfectant was analyzed with one-way ANOVA and post-hoc Tukey test. Results: The highest and lowest efficiency to remove C. albicans biofilm was identified for 1% sodium hypochlorite and 4% chlorhexidine gluconate. The efficiency of 1% and 2% sodium hypochlorite solution to remove biofilm showed no statistical difference. SEM analysis indicated that after the application of 1% and 2% sodium hypochlorite no fungal cells were observed, and application of 4% chlorhexidine gluconate revealed a few remaining blastospores and hyphal cells attached to the resin surfaces. Conclusions: Disinfection with 1% and 2% sodium hypochlorite solutions revealed the most impressive results to reduce the C. albicans biofilm formation than 4% chlorhexidine gluconate solution.

A comparison of wear rate of direct and indirect resin composites: A two-body wear abrasion test

Purpose The objective of this in vitro study was to investigate and compare two-body wear of hybrid, microhybrid, and nanohybrid direct and indirect composite resins. Materials and methods A pin-on-disc wear device was used to study the effects of the water on two-body wear rate of two microhybrid composites (Solidex® and Dialog®), a nanohybrid composite (Grandio®SO), and three direct composite resins: a hybrid composite (Herculite Classic™), a submicron hybrid composite (Charisma®), and a nanohybrid composite (Tetric® N-Ceram). For testing, 12 specimens of each material with 6.5 mm diameter and 4 mm height were made and half of the specimens were stored in the distilled water for 1 week at 37℃. In order to evaluate the wear rate of samples, a normal load of 15 N was applied to specimen’s surface. The 6.5 mm diameter composite sample held to pin holder and AISI 316 L stainless steel was employed as the disc. The following experimental parameters were kept constant for all tests: sliding velocity = 0.6 m/s, temperature 25 ± 3℃, 1.2 Hz, and 10,000 cycles. One-way Analysis of Variance (ANOVA) and post hoc Tukey’s test were performed to compare the wear rate of resin composites. Results Ranking of wear rate (most to least) without water exposure was as follows: Dialog>Solidex>Charisma>GrandioSO>Tetric Ceram=Herculite. No significant difference in wear was observed between GrandioSO, Tetric N-Ceram, and Herculite Classic, with and without water exposure (p > .05, respectively). Conclusions The nanohybrid resins—regardless of indirect or direct use—showed significantly less abrasive wear than the microhybrid resins.