Labor reduction for mold preparation of a commercial titanium cast denture system using a heat-shock method.
The purpose of this study was to investigate the application of a heat-shock method to fabricate titanium cast plates. Duplications of a maxillary model were prepared using DM under different firing schedules. Molds with patterns on the duplications were made by an outer investment (D), followed by heat shock at 850 degrees C. Duplications heat shocked at 850 degrees C after 30 min from mixing exploded within a few minutes. This explosion was successfully avoided by a drying procedure prior to the heat-shock. The molds were available for the heat shock at 850 degrees C when the duplicate models were prepared by firing either using the conventional method and the heat shock above method described. Therefore, we could reduce the preparation time from about 16 hr with the conventional method to about 10 hr at the longest with the heat-shock method. These results suggested that the heat-shock method was labor-saving for fabricating titanium cast denture plates when controlling preliminary conditions prior to use. (+info)
Retention force of complete palate coverage and palate-less dentures in vitro.
The purpose of this study was to investigate the retention force of complete palate coverage and palate-less dentures made with three polymerization systems (DS system, SR-Ivocap system, microwave polymerization system) in vitro. The retention force between each denture and a polyurethane model by intervening artificial saliva was measured using a tensile tester. In addition, discrepancies between the denture base and the stone cast were measured at several points. The retention force of complete palate coverage and palate-less dentures made with the 3 polymerization systems shows that the DS system had a greater retention force than the SR-Ivocap system and the microwave system. Moreover, the retention force of palate-less dentures was greater than that of complete dentures only in the case of the DS system. The interaction of the polymerization system and the denture type also had a statistically significant effect on the retention force. Dentures made with the DS system had smaller discrepancies compared with dentures processed with the other systems. The retention force correlated very closely with discrepancies at the denture border and the residual ridge. (+info)
Prosthodontic rehabilitation in Papillon-Lefevre syndrome: a case report.
Papillon-Lefevre syndrome is a rare recessive genetic disorder. The clinical manifestations include palmar-plantar hyperkeratosis with precocious rapidly progressive periodontal disease that results in premature exfoliation of primary and permanent dentitions. Patients are often edentulous at an early age. Here is the report of prosthodontic rehabilitation of a case of Papillon-Lefevre syndrome in a 6-year-old child. (+info)
Dimensional stability of distances between posterior teeth in maxillary complete dentures.
The aim of this study was to assess the displacement of posterior teeth in maxillary complete dentures stored in water at 37 degrees C. Twenty acrylic resin-based maxillary complete dentures were constructed with the anterior teeth arranged in normal overlap and the posterior teeth in Angle class I. Metallic pins were placed on the labial cusp of the first premolars (PM), and on the mesiolabial cusp of the second molars (M). The final acrylic resin pressing was made in a metallic flask with aid of the RS tension system, and polymerized in a moist-hot cycle at 74 degrees C for 9 hours. The dentures were deflasked after cooling in their own polymerizing water or after cooling in polymerizing water plus bench storage for 3 hours, and stored in water at 37 degrees C for periods of 7, 30, and 90 days. Following deflasking and after each storage period tested, the PM-PM (premolar to premolar), M-M (molar to molar), LPM-LM (left premolar to left molar), and RPM-RM (right premolar to right molar) distances were measured with an STM Olympus microscope, with an accuracy of 0.0005 mm. Collected data were submitted to ANOVA and Tukey's test (5%). There was no statistically significant difference for the PM-PM, M-M, and LPM-LM distances after all storage periods when the flask cooling methods were considered. With exception of the RPM-RM distance after the 30-days water plus bench storage period, the other distances remained statistically stable. (+info)
Carving of a master cast to obtain a posterior palatal seal of a complete maxillary denture as performed by four prosthodontists: a pilot study.
This study was conducted to clarify the degree to which a master cast needs to be carved to obtain a posterior palatal seal according to Swenson, based on a comparison among four dental practitioners. Sections of the casts with the seal scraped were made, and an optical microscope was used to measure the sagittal and vertical dimensions. It was found that the sagittal dimension may show a smaller difference in carving of the master cast in the posterior palatal seal area. The present results also suggest that the clinical experience of the prosthodontist in applying this method seems to have an effect on the carved shape and depth of the posterior palatal seal. (+info)
Denture-induced fibrous hyperplasia. Treatment with carbon dioxide laser and a two year follow-up.
Denture-induced fibrous hyperplasia (DIFH) is a persistent lesion caused mostly by the prolonged wear of an ill-fitting, over-extended denture. Although the condition frequently coexists with denture stomatitis, it is a distinct entity with a different protocol for management. The article describes successful treatment for a case of DIFH using carbon dioxide laser and a two year follow-up. The inherent advantages of using carbon dioxide laser over conventional surgical techniques are discussed. (+info)
Hypertrophy of the mandibular coronoid process and structural alterations of the condyles associated with limited buccal opening: case report.
This paper reports the case of a patient who presented limited buccal opening, though, without apparent symptomatology. The patient was partially toothless and exodontia of the remaining teeth was indicated. Clinical examination and clinical interview were performed as well as panoramic radiograph, transcranial radiograph of the temporomandibular joints (TMJ) and, later, computed tomography (CT), emphasizing the importance of complementary exams in the diagnostic phase. Analysis of the CT scan confirmed the structural alteration in the condylar and coronoid processes of the jaw, explaining the limited buccal opening. The remaining teeth were extracted and complete upper and lower dentures were fabricated, reestablishing the occlusal relationship and the patient's stomatognathic functions. Surgical treatment of the coronoid process was discarded. (+info)
Influence of storage period and effect of different brands of acrylic resin on the dimensional accuracy of the maxillary denture base.