Effect of orthodontic bonding with different surface treatments on color stability and translucency of full cubic stabilized zirconia after coffee thermocycling / 대한치과교정학회지

Objective@#To assess the color stability and translucency of full cubic stabilized zirconia (FSZ) following orthodontic bonding with different surface treatments and coffee thermocycling (CTC). @*Methods@#This in vitro study was conducted on 120 disc-shaped specimens of FSZ. Thirty specimens were selected as the control group and remained intact. The remaining specimens were randomly divided into three groups based on the type of surface treatment (n = 30): airborne particle abrasion (APA), silica-coating (CoJet), and carbon dioxide (CO2) laser. After metal bracket bonding in the test groups, debonding and polishing were performed. Subsequently, all specimens underwent CTC (10,000 cycles). Color parameters, color difference (ΔE00), and translucency parameter (TP) were measured three times at baseline (t0), after debonding and polishing (t1), and after CTC (t2). Data were statistically analyzed (α = 0.05). @*Results@#Significant difference existed among the groups regarding ΔE00t0t2 (p < 0.001). The APA group showed minimum (ΔE00 = 1.15 ± 0.53) and the control group showed maximum (ΔE00 = 0.19 ± 0.02) color stability, with no significant difference between the laser and CoJet groups (p = 0.511). The four groups were significantly different regarding ΔTPt0t2 (p < 0.001). Maximal increases in TP were noted in the CoJet (1.00 ± 0.18) and APA (1.04 ± 0.38) groups while minimal increase was recorded in the control group (0.1 ± 0.02). @*Conclusions@#Orthodontic treatment makes zirconia restorations susceptible to discoloration and increased translucency. Nonetheless, the recorded ΔE00 and ΔTP did not exceed the acceptability threshold.

Frequency of different maxillary sinus septal patterns found on cone-beam computed tomography and predicting the associated risk of sinus membrane perforation during sinus lifting

PURPOSE: Analyzing different patterns of maxillary sinus septa in cone-beam computed tomography (CBCT) images and predicting maxillary sinus membrane perforations. MATERIALS AND METHODS: In this cross-sectional study, CBCT images of 222 patients ranging from 20 to 81 years old were evaluated. One hundred fifty-two patients (93 females and 59 males) who had maxillary sinus septa in axial views were included in this study. Cross-sectional images were used to determine classifications of sinus septa and the risk of membrane perforation using a method modified from Al-Faraje et al. Variables of sex, age, and dental status were considered. Chi-squared and Kruskal-Wallis tests were used for data analysis (P 0.05). CONCLUSION: A higher prevalence of moderate risk of membrane perforation in the molar region relative to the premolar region was observed. Furthermore, maxillary sinus septa occur most frequently in the molar region, demonstrating the importance of paying attention to this region during sinus lift surgery. This study did not show any relationship between tooth loss and the presence of septa.

accuracy of four impression-making techniques in angulated implants based on vertical gap

Statement of the Problem: Precision of the impression taken from implant positions significantly determines accurate fit of implant-supported prostheses. An imprecise impression may produce prosthesis misfit

Purpose: This study aimed to evaluate the accuracy of four impression-making techniques for angulated implants by stereomicroscope through measuring the vertical marginal gaps between the cemented metal framework and the implant analog

Materials and Method: A definitive cast with two 15° mesially angulated implants served as the standard reference for making all the impressions and later for accuracy evaluation. Four groups of five samples were evaluated: [1] closed-tray snap-fit transfer, [2] open-tray nonsplinted impression coping, [3] metal splinted impression coping, and [4] fabricated acrylic resin transfer cap. A gold-palladium framework was fabricated over the angulated implant abutments, the fit of which was used as reference. The gaps between the metal framework and the implant analogs were measured in sample groups. Corresponding means for each technique and the definitive cast were compared by using ANOVA and post hoc tests

Results: The mean marginal gap was 38.16+/-0um in definitive cast, 89+/-19.74um in group 1, 78.66+/-20.63um in group 2, 54.16+/-24.29um in group 3, and 55.83+/- 18.30um in group 4. ANOVA revealed significant differences between the definitive cast and groups 1 and 2, but not with groups 3 and 4 [p< 0.05]

Conclusion: Vertical gap measurements showed that metal splinted impression coping and fabricated acrylic resin transfer cap techniques produced quite more accurate impressions than closed-tray snap-fit transfer and open-tray nonsplinted impression coping techniques do

The fabricated acrylic resin transfer cap tech-nique seems to be a reliable impression-making method

[Fabrication of a hybrid screw-retained and cement-retained implant prosthesis: a case report]

Various prosthodontic techniques are used for treatment of implant patients. Fabrication of a cement-retained prosthesis on a screw-retained framework is among these techniques. This type of prosthesis is usually indicated for implants that have been insertedobliquely or in an improper position. Easy retrieval, repair and maintenance are the main advantages of this type of prosthesis. The present articledescribes a method for fabrication of implant supported prosthesis. In this prosthesis, separate crowns are cemented on a screw-retained framework. The metal framework is coated with gingival-colored porcelain in order to support soft tissue. Our patient was a completely edentulous 56 year-old female suffering from severe bone loss as the result of long term use of dentures. The bone resorption was so severe that the normal ridge contour could not be restored even after extensive ridge augmentation using iliac crest bone graft. Thus, a combination of cement-retained and screw-retained prostheses was selected as the treatment of choice for this patient. This technique combines the advantages of both screw-retained and cement-retained prostheses in terms of function and esthetics. Also, despite the hardly-accessible location of the screw access channel in the framework, assessment of implants is always feasible by unscrewing the metal framework. Additionally, the fabricated crowns can be easily repaired or replaced without the need for unscrewing the framework