ABSTRACT
Objectives: the present study evaluated the effect of bar and ball attachment designs on retention and stability of a mandibular overdenture supported by four implants
Methods: an edentulous mandibular acrylic resin model with four implants in the anterior part of the ridge [A, B, D and E] was fabricated. A metal framework simulating the overdenture was also fabricated. Totally, 30 overdentures were divided into three groups based on the attachment design; BL: Four ball attachments in A, B, D and E positions; BB: One bar attachment between B and D positions and two ball attachments at positions A and E; BR: Bar attachments between the positions A, B, D and E with two posterior extensions. To evaluate the retention and stability of the overdenture, tensile dislodging forces were applied in three directions of vertical, oblique and anterior-posterior by a universal testing machine. One-way ANOVA and Tukey's HSD test were performed to analyze the data. All tests were carried out at 0.05 level of significance
Results: there were statistically significant differences between the groups in the peak load [P<0.001]. The peak load values for vertical, oblique and anterior-posterior dislodging forces were the highest for BL with 49.38 +/- 2.19 N, 52.19 +/- 1.44 N, and 49.03 +/- 5.89 N, respectively, while these values were the lowest for BR with 29.78 +/- 2.52 N, 12.10 +/- 0.45 N, and 6.26 +/- 0.45 N, respectively
Conclusion: the attachment designs affected the retention and stability of mandibular implant-supported overdentures
ABSTRACT
PURPOSE: This in vitro study evaluated the effects of four different cements on the color attributes of a zirconia ceramic. MATERIALS AND METHODS: 40 zirconia ceramic disk specimens (0.5 mm thickness, 10 mm diameter, 0.1 mm cement space) were fabricated by a computer-aided design and computer-aided manufacturing system. The specimens were divided into 4 groups of 10 specimens and cemented to composite substrates using four different cements including: Glass Ionomer, Panavia F2.0, Zinc Phosphate, and TempBond. The L*, a*, and b* color attributes of the specimens were measured before and after cementation by a spectrophotometer. Additionally, ΔE values were measured to determine color changes for the groups and then compared with the perceptional threshold of ΔE = 3.3. Repeated Measures ANOVA, Tukey Post Hoc, Bonferroni, One-way ANOVA, and One-sample t-test tests were used to analyze the data. All tests were carried out at the 0.05 level of significance. RESULTS: Statistically significant differences were detected in the ΔE values for Zinc Phosphate (P<.0001) and TempBond (P<.0001) groups. However, there were no statistically significant differences in this respect for Glass Ionomer (P=.99) and Panavia F2.0 (P=1) groups. The means and standard deviations of the ΔE values for Glass Ionomer, Panavia F2.0, Zinc Phosphate, and Tempbond groups were 2.11±0.66, 0.94±0.39, 5.77±0.83, and 7.50±1.16 Unit, respectively. CONCLUSION: Within the limitations of this study, it was concluded that Zinc Phosphate and Tempbond cements affected the color attributes of the tested zirconia ceramic beyond the perceptional threshold. However, Glass Ionomer and Panavia F2.0 cements created acceptable color changes.
Subject(s)
Cementation , Ceramics , Computer-Aided Design , Dental Cements , Glass , In Vitro Techniques , Spectrophotometry , ZincABSTRACT
Objectives: Microtia is the most commonly seen congenital ear defect, and involves an auricular deformity either unilaterally or bilaterally. The aim of this study was to fabricate silicone prostheses for a child with bilateral microtia using an innovative technique.
Methods: This method involved the construction of bilateral ear prostheses using clips, which were located within the layers of the silicone superstructure.
Results: Surgical reconstruction was not indicated due to the patient's age; so prosthetic reconstruction was advised in this case.
Discussion: Two prosthetic ears were manufactured, with one being attached using an adhesive method and the other by a self suspension method. The child and his parents were very satisfied by the cosmetic and aesthetic appearance of the prostheses fitted. This technique has been proven to be suitable for pediatric patients with microtia
ABSTRACT
The aim of this study was to compare retention of implant-tissue supported overdentures with ball attachments in the most anterior and posterior implant positions at symphysis. An acrylic resin model of edentulous mandible with no undercuts was fabricated .Two pairs of implants, two by two, were placed symmetrically in the most anterior and posterior positions at symphysis. Two were placed 5mm from midline in anterior position while two others 5mm infront of mental foramina site in posterior position. A metallic overdenture was made on the model precisely. Then an over denture housing was prepared on the frame work and joined to it. The ball abutments were screwed on the pair of implants in different positions and the complex of attachment housing and clinical insert, were attached into the over denture housing. Five samples were tested for each position. Zwick testing machine loaded and measured tensile forces invertical direction for each sample. Maximum Dislodging Force [MDF] was recorded at the moment of completed attachment of over denture from the model. Independent sample T-test was performed to analyse the data and results reported by confidence coefficient of 95%. There was no statistically difference in retention of implant-tissue supported over dentures in the most anterior and posterior positions of implants at symphyseal region [P>0.05]. The amount of retention is the same in the most anterior and posterior positions of implants in anterior mandible