Nur Hersek

Color stability of denture base acrylic resins in three food colorants

STATEMENT OF PROBLEM Three commonly used artificial dyes in food technology are erythrosine, tartrazine, and sunset yellow. PURPOSE The color stability of 5 commercially available denture base acrylic resins (QC-20, Meliodent, Trevalon, Trevalon High, and Lucitone) was studied in vitro. METHODS The specimens were exposed to 3% erythrosine, tartrazine, and sunset yellow solutions at 23 degrees C +/- 1 degrees C. Color changes were determined with a computer-controlled spectrophotometer. Five specimens from each material were processed, and initial color measurements were made after 1, 3, and 6 months of exposure to the staining solutions. Finally, the color stability was quantitatively measured again, and color differences (DeltaE) were calculated. RESULTS For the observations made in 1, 3, and 6 months intervals, the specimens that exhibited the least color change were in the sunset yellow solution. The greatest color changes observed according to the National Bureau of Standards unit system were Lucitone (2.71) in erythrosine solution, Lucitone (2.54), QC-20 (1.71) in tartrazine solution, and QC-20 (1.66) in sunset yellow solution. The changes in the other acrylic resins in the 3 solutions were slight and at trace level. CONCLUSIONS All materials tested were acceptable from the standpoint of color stability for long-term exposure to these food colorants.

Comparison of the Fracture Resistance of Six Denture Base Acrylic Resins

Fracture strength of denture base resins is of great concern, and many approaches have been used to strengthen acrylic resin dentures. Fracture resistance of six commercially available acrylic resin denture base materials were compared, through impact and transverse strength tests. Three rapid heat-polymerised resins (QC 20, Meliodent and Trevalon), two high-impact strength resins (Trevalon Hi and Lucitone 199) and a strengthened injection-moulded acrylic resin (SR Ivocap plus) were included in the study. Twenty acrylic resin test specimens were fabricated from each resin. For impact strength test, ten notched specimens were tested in a Charpy-type impact tester. The other ten specimens were used for transverse strength tests, deflection and modulus of elasticity values were also determined, which were assessed with three-point bending tests using an Universal Testing Machine. Impact test values showed significant differences among acrylic resins (F = 4.817 p = 0.0). SR Ivocap resin showed the highest impact strength values, followed by Trevalon Hi and Lucitone 199. The transverse strength test values were not significant when six acrylic resins were compared (F = 1.705 p = 0.151). High-impact resins can be recommended to increase the impact strength of denture base. If the cause of fracture is mechanical or anatomical, strengthened acrylic resins and conventional acrylic resins have similar fracture resistance.

Effect of muscle relaxation splint therapy on the electromyographic activities of masseter and anterior temporalis muscles.

The purpose of this study was to compare the effectiveness of splint therapy on the electromyographic activity of masticatory muscles (anterior temporalis and masseter) before and after the application of a muscle relaxation splint. Electromyography recordings from the masseter and anterior temporalis muscles were analyzed quantitatively during maximal biting in the intercuspal position both before and after treatment without a splint. Fourteen patients whose chief complaint was masticatory muscle pain were selected for the study. After the initial evaluations muscle relaxation splints were applied, and the patients were instructed to use the splints for 6 weeks. Surface electromyographic recordings were taken from each patient before the beginning of clinical therapy and after 6 weeks of wearing the splints. The data obtained were analyzed through paired sample t tests and Wilcoxons signed rank tests. The results of the study were as follows: (1) the electromyographic activity of the two muscles during maximal biting was not markedly changed after the muscle relaxation splint was used; and (2) the changes observed in electromyographic activity of the involved and noninvolved sides were insignificant as well.

Oral health status in a group of the elderly population residing at home.

OBJECTIVES To determine the oral health status and treatment needs of subjects aged 65 years and older residing in different districts of Ankara. MATERIALS AND METHODS A total of 1300 patients, 751 females and 549 males, age 65 and over with a mean age of 72.8 ± 6.34 were included in this study. The subjects were visited at home and toothbrushing habits, visiting the dentist, tooth loss, denture needs were questioned and body mass index values were recorded. RESULTS 52.5% of the subjects were completely edentulous, 83.3% subjects reported wearing a removable denture. Females had a higher total tooth loss frequency when compared to males (p < 0.05). Total tooth loss between 65 and 69 ages was 47.3%, and increased to 62.4% among those aged 75 and over (p < 0.05). 16.2% of the subjects had not visited a dentist in the last 10 years, and only 3% visited a dentist for control check-ups; no gender-based difference was observed as to the frequency of dental visits (P > 0.05). No significant relationship was found between tooth loss and BMI values (P > 0.05). 46.3% of the subjects had chewing problems. CONCLUSIONS The subjects included in this study showed high tooth loss frequency and poor oral hygiene habits. Education regarding maintenance of oral hygiene and regular dental check up should be stressed for the elderly.

Effect of Anterior Repositioning Splints on the Electromyographic Activities of Masseter and Anterior Temporalis Muscles

The effect of anterior repositioning (AR) splint therapy on masticatory muscle activity was investigated in seventeen patients with internal derangement; disk displacement with reduction in particular. Integrated electromyography (EMG) recordings from the masseter and anterior temporalis muscles were analyzed quantitatively during maximal biting in intercuspal position before and after eight week treatment period, EMG recordings were taken for each subject prior to the beginning of clinical therapy and final EMG recordings were made without AR splint to provide a standard for comparison. The results of the investigation revealed the following: 1. AR splint therapy did not cause any significant modification of the EMG activity in the recorded muscles during maximal biting in intercuspal position; 2. Before and after treatment the EMG activity from the masseter muscle was less than from the temporal muscle; 3. AR splint therapy resulted in reduction of the pain (88.2%) and jaw joint sounds (64.7%) and mean vertical opening which was 42.17 mm before treatment increased to 45.06 mm.