Patient satisfaction and masticatory performance of zirconia bar compared to cobalt chromium bar retaining mandibular implant overdenture: A crossover study

Incorporating Stud Attachments in the Bar Design for an Implant-Supported Overdenture

Bone resorption following tooth loss might compromise retention, stability, and support of conventional removable prostheses, and for this reason, implant-supported overdentures are suggested as a viable alternative for completely edentulous patients. Bars, telescopic attachments, or stud attachments have been used to provide retention through a different mechanism of action based on specific design characteristics. The purpose of this report is to thoroughly describe the applied protocol for the fabrication of an implant overdenture supported by two bars incorporating stud attachments. A 67-year-old male patient presented to the Postgraduate Clinic of the National and Kapodistrian University in Athens seeking dental rehabilitation. The remaining teeth were characterized with poor prognosis, mainly due to their periodontal status. The proposed treatment plan included the placement of four implants in the maxilla and two implants in the mandible and the fabrication of implant-supported overdentures. The diagnostic stages revealed adequate prosthetic space that would enable the fabrication of a bar substructure for the maxillary overdenture. To combine the benefits of bars and stud attachments, two bars with four attachments were fabricated. Evaluation of the delivered prosthesis revealed adequate retention, support, and stability achieved with minimal palatal coverage. Patient's reported satisfaction and quality of life were increased. Recall appointments at one, six, and twelve months did not reveal any adverse effects or patient's complaints. According to the present case report, different types of attachments may be used after careful study of each case. More studies are needed to report on different aspects of the chosen treatment plan.

A systematic review and meta-analysis of the clinical performance of implant-supported overdentures retained by CAD-CAM bars

Currently, there is no consensus on the indications and clinical performance of implant-supported overdentures (IODs) involving computer-aided design and manufacturing (CAD-CAM) bars.

OBJECTIVE

To evaluate the performance of IODs involving CAD-CAM bars.

METHODOLOGY

A comprehensive search of studies published until May 2023 was conducted in many databases, including PubMed/MEDLINE, Web of Science, Cochrane Library, and SciELO, following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA). The population, intervention, comparison, outcome (PICO) question was: "How do IODs retained by bars fabricated by CAD-CAM technology perform in daily clinical practice?" The meta-analysis included clinical studies based on effect size and a two-tailed null test with a 95% confidence interval (CI).

RESULTS

Ten studies were included in the meta-analysis. Among them, nine reported a 100% implant survival rate for all CAD-CAM milled bars. Complications were reported in two studies with CAD/CAM-milled titanium bars, and one study reported more fractures in soldered gold bars used in maxillary rehabilitation. However, no fractures were observed in IODs retained by PEEK and zirconia bars. According to six studies, biological complications, including peri-implantitis, were minimal in the BioHPP and PEEK bar groups, while no cases were reported in the titanium or zirconia bar groups. CAD-CAM-milled zirconia bars had higher plaque and bleeding indices compared with titanium bars, as evidenced by findings from five studies. All four studies that evaluated Oral Health Impact Profile (OHIP) scores showed a positive effect of IODs retained by CAD-CAM milled titanium bars on quality of life. Patient satisfaction and acceptance by prosthodontists were significantly high, according to the results of five studies.

CONCLUSION

Overdentures retained with CAD-CAM milled titanium bars show great potential for use in daily clinical practice. Moreover, patient and practitioner satisfaction was very high when this method was used.

Influence of ZrO2 Nanoparticle Addition on the Optical Properties of Denture Base Materials Fabricated Using Additive Technologies

This study investigated the translucency of 3D-printed denture base resins modified with zirconium dioxide nanoparticles (ZrO₂NPs) under thermal cycling. A total of 110 specimens were fabricated and divided into 3 groups according to the materials, i.e., heat-polymerized resin, and 3D-printed resins (NextDent, and ASIGA). The 3D-printed resins were modified with 0, 0.5, 1, 3, and 5 wt.% of ZrO₂NPs. All the specimens were subjected to 5000 thermal cycles. The translucency was measured using a spectrophotometer. The results showed that the heat-polymerized resin had considerably higher translucency than the 3D-printed resins. Compared to the unmodified group, the translucency decreased significantly after adding 5% ZrO₂NPs to NextDent and 3% ZrO₂NPs to ASIGA resins. The highest translucency was achieved for NextDent by adding 0.5% ZrO₂NPs and for ASIGA without any ZrO₂NPs. It was found that the average concentration level in ASIGA was significantly higher than that in NextDent. These findings revealed that 3D-printed resins have lower translucency than heat-polymerized acrylic resin, and adding ZrO₂NPs at low concentrations did not affect the translucency of the 3D-printed resins. Therefore, in terms of translucency, 3D-printed nanocomposite denture base resins could be considered for clinical applications when ZrO₂NPs are added at low concentrations.

Translucency parameter and color masking ability of CAD/CAM denture base materials against metal substrates

PURPOSE

To investigate the translucency parameters of traditional, milled, and 3D-printed denture base materials at 3 different thicknesses and the color masking ability of each material against a metallic background between different thicknesses.

MATERIAL AND METHODS

A traditional heat-polymerizing polymethylmethacrylate (PMMA) (H-Lucitone) material was used as the control group. Two milled pre-polymerized resin blocks (M-Lucitone and IvoBase) and five 3D-printed denture base materials (P-Lucitone, Dentca LP, Dentca OP, Formlabs, and Kulzer) were used as experimental groups. A total of 240 samples, (n = 30, per material) were fabricated to a final specimen dimension of 12×12 mm and in thicknesses of 1.0, 2.0, and 3.0 mm (n = 10 per thickness/material) according to the manufacturers' recommendations. The color coordinates (L*, a*, b*) in CIELab color space for all specimens placed against a white, black, and metallic background were measured with a spectrophotometer. The translucency parameters (TP₀₀ ) at each thickness and the color differences between 1 mm and 2 mm (dE_00M1-2 ) and between 2 mm and 3 mm (dE_00M2-3 ) against the metallic background were calculated with the CIEDE2000 color matrix. Comparisons between the groups for differences in TP₀₀ were made using One-way ANOVA separately for each thickness. Comparisons of groups and materials for differences in dE_00M1-2 and dE_00M2-3 were made using Two-way ANOVA and Fisher's Protected Least Significant Differences (α = .05).

RESULTS

The TP₀₀ decreased with increasing thickness in all 8 material groups. All 3D-printed materials, except P-Lucitone, had higher TP₀₀ than milled pre-polymerized resin materials (M-Lucitone and IvoBase), and traditional heat-polymerizing PMMA (H-Lucitone) material (P<.001) at all thicknesses. In the 1 mm and 2 mm thickness, heat-polymerizing acrylic resin (H-Lucitone) had the lowest TP₀₀ , and in the 3 mm thickness, milled acrylic resin (M-Lucitone and IVOBase) had had lowest TP₀₀ (P<.001). All material groups had significantly lower values of dE_00M2-3 than dE_00M1-2 (P<.001). The color differences dE_00M2-3 were significantly lower in H-Lucitone, M-Lucitone, P-Lucitone, and IvoBase groups than in other materials, while the color difference of dE_00M1-2 was significantly lower in H-Lucitone, P-Lucitone and Dentca LP than other materials (P<.001).

CONCLUSIONS

The results from this study provide clinicians and dental technicians with information regarding the selection of denture base materials to achieve desired color masking outcomes, according to available prosthetic space. Thicker prostheses significantly improved the color masking abilities of denture acrylic resins against a metallic background. In a thickness of 1 and 2 mm, the heat-polymerizing acrylic resin had a lower translucency parameter and better color masking ability. When the prosthesis thickness reached 3 mm, the milled acrylic resin had a lower translucency parameter and better color masking ability. When compared to the heat-polymerizing resin and milled acrylic resin materials, except for one 3D-printing resin (P-Lucitone), the color masking abilities of the remaining 3D-printing resin materials were low, regardless of prosthesis thickness. This article is protected by copyright. All rights reserved.