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Obturator prostheses for hemimaxillectomy patients

Maxillary defects are created by surgical treatment of benign or malignant neoplasms, congenital malformation and by trauma. The size and location of the defects influence the degree of impairment and difficulty in prosthetic rehabilitation. Lack of support, retention, and stability are common prosthodontic treatment problems for patients who have had a maxillectomy. A prosthesis used to close a palatal defect in a dentate or edentulous mouth is referred to as an obturator. The obturator prosthesis is used to restore masticatory function and improve speech, deglutition and cosmetics for maxillary defect patients.

Evaluation of gloss changes of two denture acrylic resin materials in four different beverages.

OBJECTIVES The primary disadvantages of the materials which are used in construction of complete and removable partial dentures is that their esthetic, physical and mechanical properties change rapidly with time in the oral environment. For esthetics, color stability is one of the criteria that needs careful attention. Color may provide important information on the serviceability of these materials. Color change affects the gloss of these materials. The objective of the present study was to determine the gloss changes resulting from the testing process in four different beverages in one heat-polymerized denture base resin and one cold-polymerized denture base repair resin. METHODS Thirty-six samples were fabricated for each material. Each sample had a smooth polished and a rough unpolished surface. The gloss measurements were made with a glossmeter before testing. Four different beverages (tea, coffee, cola and cherry juice) were used for testing. Two angles of illumination (20 and 60 degrees) were used for the gloss measurements. The samples were immersed in water, tea, coffee, cola and cherry juice solutions. The gloss of the samples was measured again with the glossmeter at the end of the 45th day and 135th day of testing. The arithmetic mean and standard deviation of each of the samples were calculated and compared with each other statistically by using the Wilcoxon test (within times) (p < or = 0.05 significant), the Kruskal-Wallis analysis of variance (p < or = 0.05 significant) and the Mann-Whitney U-test with Bonforoni correction (when the difference between the samples was significant) (p < or = 0.05 significant). RESULTS The results of this study revealed that gloss changes occurred after testing in heat-polymerized denture base resin and cold-polymerized denture base repair resin. The significance of the gloss changes exhibited by each sample, kept for different lengths of time in the same solution, were compared using the Wilcoxon test. The results were statistically significant (p < or = 0.05). According to the Kruskal-Wallis analysis of variance, the difference between measurements for angles of illumination was statistically significant (p < or = 0.05). Also according to the Mann-Whitney U-test, the difference between two polished surfaces or two unpolished surfaces was statistically insignificant (p > 0.05), but the difference between smooth polished and rough unpolished surfaces was statistically significant (p < or = 0.05). SIGNIFICANCE It was found that either the gloss of heat-polymerized denture base resin or the gloss of cold-polymerized denture base repair resin was affected by tested agents, and the four beverages demonstrated noticeable gloss changes. Cherry juice demonstrated the least change, while tea exhibited the greatest change.

Comparison of Effects of Bleach and Cleansing Tablet on Reflectance and Surface Changes of a Dental Alloy Used for Removable Partial Dentures

Proper hygienic care of removable partial dentures is important for maintaining a healthy oral mucosa. A daily home care routine is the responsibility of the patient to maintain oral hygiene. A dentist must inform the patient about denture cleansers used for plaque control. Common denture cleansers may negatively affect the surface of alloys used to make partial dentures. The purpose of this study was to evaluate whether bleach and cleansing tablet have deleterious effects on the surface of a dental alloy used to fabricate removable partial dentures. Nineteen test specimens were prepared from CoCr dental alloy. The specimens were cast into 10 mm long × 10 mm wide × 1 mm thick. Fresh solutions made from a commercial bleach and a commercial cleansing tablet were used for each treating. Three groups (commercial denture cleansing tablet, bleach and tap water) were tested. Six specimens were immersed in 200 mL of tap water containing a single denture cleansing tablet. Two spoons of the commercial bleach was added to 200 mL of tap water. Seven specimens were treated. The control specimens were immersed in 200 mL of tap water. Six specimens were the control group. Each specimen was immersed for 30 min per day in the solution for a period of 30 days. The specimens were analyzed for reflectance with a spectrophotometer, for surface changes with a light microscope and weight which was measured with sensitive balance before and after treatment. The SPSS program was used for the statistical analysis. The Kruskal-Wallis Test and Wilcoxon Signed Ranks Test was used. No significant changes of reflectance was shown in the Kruskal-Wallis Test (p > 0.05). The Wilcoxon Signed Ranks Test was performed for comparison into groups. The difference between before and after treatment was statistically significant for the commercial denture cleansing tablet and the commercial bleach (p = 0.028) (p<0.05). Reflectance was decreased after treatment. Within the limitations of this study, the commercial cleaning solutions had influenced the decrease of reflectance on the surface of the dental alloy. This solutions should not be limitlessly used on dentures with metal components, because they caused clinically significant reflectance changes on the surface of the alloy after 30 days.

The influence of the pure metal components of four different casting alloys on the electrochemical properties of the alloys

OBJECTIVES The aim of this study was to investigate the influence of the pure metal components of the four different casting alloys on the corrosion behaviors of these alloys tested. METHODS Potentiodynamic polarization tests were carried out on four different types of casting alloys and their pure metals at 37 degrees C in an artificial saliva solution. The ions released from the alloys into the solutions during the polarization test were also determined quantitatively using inductively coupled plasma-mass spectrometry (ICP-MS). RESULTS Ni-Cr (M1) and Co-Cr (M2) alloys had a more homogenous structure than palladium based (M3) and gold based (M4) alloys in terms of the pitting potentials of the casting alloys and those of the pure metals composing the alloys. The total ion concentration released from M3 and M4 was less than from M1 and M2. This may be because M3 and M4 alloys contained noble metals. It was also found that the noble metals in the M3 and M4 samples decreased the current density in the anodic branch of the potentiodynamic polarization curves. In other words, noble metals contributed positively to dental materials. SIGNIFICANCE Corrosion resistance of the casting alloys can be affected by the pure metals they are composed of. Au and Pd based noble alloys dissolved less than Ni-Cr and Co-Cr based alloys.

The electrochemical properties of four dental casting suprastructure alloys coupled with titanium implants

Objectives: As the choice of suprastructure alloy to be combined with titanium for the oral cavity is still a much debated issue, the aim of this study was to investigate the electrochemical interaction of the suprastructure/implant couples under the determined experiment conditions. Material and Methods: The potentiodynamic polarization curves and open-circuit potentials (OCP) of four UCLA type suprastructures coupled with straight Swiss Plus implant fixtures were taken in Afnor type artificial saliva solution at 37°C. The concentration of ions leached into artificial saliva solutions was estimated with ICP-MS. SEM images of the margins of suprastructure/implant couples were obtained before and after the electrochemical tests. Results: The OCP value of titanium became passive at the most negative potential. The lowest difference between the initial and constant OCP value was exhibited by the Au based suprastructure. Suprastructures made greater contributions to the potentiodynamic polarization curves of the implant/suprastructure couples. According to the ICP-MS results, Pd based and Au based couples dissolved less than Co-Ni based and Co-Cr based couples. Conclusions: Within the conditions this study, it may be concluded that the titanium implant forms a stable passive oxide layer in artificial saliva exposed to open air and does not affect the corrosion properties of the suprastructures. Pd based and Au based couples have been found to be more corrosion-resistant than base alloy couples.

The Effect of Fiber Reinforcement Type and Water Storage on Strength Properties of a Provisional Fixed Partial Denture Resin

Fracture resistance of provisional restorations is an important clinical concern. This property is directly related to transverse strength. Strengthening of provisional fixed partial dentures may result from reinforcement with various fiber types. This study evaluated the effect of fiber type and water storage on the transverse strength of a commercially available provisional resin under two different conditions. The denture resin was reinforced with either glass or aramid fiber or no reinforcement was used. Uniform samples were made from a commercially available autopolymerizing provisional fixed partial denture resin. Sixteen bar-shaped specimens (60 × 10 × 4 mm) were reinforced with pre-treated epoxy resin-coated glass fibers, with aramid fibers, or with no fibers. Eight specimens of each group, with and without fibers, were tested after 24 h of fabrication (immediate group), and after 30-day water storage. A three-point loading test was used to measure the transverse strength, the maximal deflection, and the modulus of elasticity. The Kruskal-Wallis Analysis of Variance was used to examine differences among the three groups, and then the Mann-Whitney U Test and Wilcoxon Signed Ranks Test were applied to determine pair-wise differences. The transverse strength and the maximal deflection values in the immediate group and in the 30-day water storage group were not statistically significant. In the group tested immediately, the elasticity modulus was found to be significant (P = 0.042). In the 30-day water storage group, all the values were statistically insignificant. The highest transverse strength was displayed by the glass-reinforced resin (66.25 MPa) in the immediate group. The transverse strength value was 62.04 MPa for the unreinforced samples in the immediate group. All the specimens exhibited lower transverse strength with an increase in water immersion time. The transverse strength value was 61.13 MPa for the glass-reinforced resin and was 61.24 MPa for the unreinforced resin. The aramid-reinforced resin decreased from 62.29 to 58.77 MPa. The addition of fiber reinforcement enhanced the physical properties (the transverse strength, the maximal deflection, the modulus of elasticity) of the processed material over that seen with no addition of fiber. Water storage did not statistically affect the transverse strength of the provisional denture resin compared to that of the unreinforced resin. The transverse strength was lowered at water storage but it was not statistically significant. The transverse strength was enhanced by fiber addition compared to the unreinforced resin. The glass fiber was superior to the other fiber. Also the modulus of elasticity was enhanced by fiber addition compared to the unreinforced resin.

The Effect of Woven, Chopped and Longitudinal Glass Fibers Reinforcement on the Transverse Strength of a Repair Resin

Fracture resistance of prosthesis is an important clinical concern. This property is directly related to transverse strength. Strengthening of prostheses may result from reinforcement with various fiber types. This study evaluated the effect of fiber type on the transversestrength of a commercially available autopolymerizing resin that is used for repairing prosthesis. The resin was reinforced with woven form, chopped form and longitudinal form, and no reinforcement was used.Uniform samples were made from autopolymerizing resin. In total, twenty-four bar-shaped specimens (60 × 10 × 4 mm) were reinforced with glass fibers. Nine specimens were prepared without fiber. Athree-point loading test was used to measure transverse strength, maximal deflection, and modulus of elasticity. The Kruskal-Wallis analysis of variance was used to examine differences between the four groups. Although the results of the analysis between these groups showed no statistical significances, the transverse strength, maximal deflection and modulus of elasticity increased more with fiber than without the fiber group. This finding may be of clinical significance. Because the addition of fiber reinforcement enhanced the physical properties of the processed material, specially woven form glass fiber was superior to the other forms.

Change in a maxillo-facial prosthesis material effecting from environmental factors: a clinical report.

The purpose of this study was to indicate change in an auricular prosthesis resulting from environmental factors. An auricular prosthesis was made from a commercially maxillo-facial dental materials. The patient used this prosthesis. After one year, the auricular prosthesis was changed, it was nonesthetic. The prosthesis was made over againfrom the beginning. The prosthesis was changed from environmental factors such as sunlight, wetting and drying, cleaning and secretions. Facial prosthesis was fabricated anew because of color changes and surface changes.

Full-Crown Castings Made with Water-Saturated and Dry Casting Ring Liners

The carcinogenic potential of asbestos has led to the development of non-asbestos materials for use as casting ring liners. Cellulose paper are replacing asbestos paper. The brass die and crown were made to produce full crowns. The standardized wax pattern was replicated twenty-nine times. Two grooves were marked on the die and wax patterns. The marginal gaps between wax pattern and die shoulder were measured. Then, the wax specimens were divided into three groups. The dry ring liner and the water-saturated ring liner were used, in the third group, any liner was used. The castings were fabricated and were fitted on the die. Measurements were made of the distance separating the gingival margin of the castings from the shoulder on the die. Measurement points (X and Y) were the same points used for wax pattern measurement. The difference between wax pattern and casting was found to be statistically significant in all the groups (p = 0.0051). There was no statistically significant difference between groups on the comparative fit of the castings. The mean marginal space in the water-saturated liner group was 0.51 ± 0.12 mm (X), 0.51 ± 0.11 mm (Y), and in the dry liner group, the mean marginal space was 0.47 ± 0.09 mm (X), 0.49 ± 0.08 mm (Y). In the unlined group, they were 0.52 ± 0.18 mm (X), 0.55 ± 0.17 mm (Y). Use of dry ring lining material resulted in smaller marginal spaces between castings and the die than use of water-saturated cellulose ring lining material. The results demonstrated that the use of dry liners may improve the fit of castings to dies.

Management of Obstructive Sleep Apnea in an Edentulous Lower Jaw Patient with a Mandibular Advancement Device

Obstructive sleep apnea (OSA) is the most common sleep-related breathing disorder with periodic reduction or cessation of airflow during sleep. It is associated with loud snoring, disrupted sleep, and witnessed apneas. Treatment of OSA varies from simple measures such as oral appliances and nasal continuous positive airway pressure (CPAP) to surgical procedures like uvulopalatopharyngoplasty and tracheostomy. Oral appliances are a viable nonsurgical treatment alternative in patients with OSA, of which mandibular advancement devices are most common. Edentulism which contributes to the worsening of OSA reduces the number of available therapeutic strategies and is considered a contraindication to oral appliance therapy. This clinical report describes the treatment of a 63-year-old edentulous OSA patient for whom a mandibular advancement device was designed.