Journal of Prosthodontics-Implant Esthetic and Reconstructive Dentistry最新文献

Purpose: The present study aims to evaluate and compare the retention forces of nylon and polyetheretherketone (PEEK) attachments with different color codes over time and denture cleansers.

Materials and methods: Two plexiglass models were prepared for this study. In the first model, two Astra-Tech EV implants and two Locator abutments were placed, followed by the placement of two corresponding housings in the opposite blocks where nylon attachments were fitted. The second model was mounted with two Medentika Microcone RI implants and two Novaloc abutments. PEEK attachments were then placed in the corresponding housings. Blue-pink-clear nylon and white-yellow-green PEEK attachments' (n = 8 for each group) maximum dislodgement forces were measured at baseline (T₀). Second measurements were conducted after 1080 insertion and removal cycles (T₁). Corega denture cleanser solution was prepared by adding one tablet to 200 mL of tap water. All attachments were soaked in the solution for three minutes and rinsed under running water. Each group of attachments was soaked for 1080 min in total, corresponding to 1 year of clinical use. The final measurements were conducted after storage in the solution. One specimen and abutment were randomly selected from each group and examined using a scanning electron microscope. The data were analyzed by repeated measures ANOVA and Bonferroni multiple comparison test (p < 0.05). The percentage decrease in the dislodgement force of the attachments was also calculated.

Results: Insertion and removal cycles significantly affected the retention values (p < 0.001). Storage in the cleanser did not significantly affect the retention (p > 0.05). The lowest retention value was observed in blue nylon attachments (501.50 ± 33.39 gf [gram force]) after insertion-removal (T₁), with a similar trend after immersion (476.13 ± 39.75 gf) (T₂). The highest retention was observed similarly in clear nylon attachments (1660.38 ± 41.73 gf) after insertion-removal after immersion (1636.50 ± 62.20 gf) (T₂). In terms of percentage loss of retention, yellow PEEK attachments were the most affected group after all test procedures (36.88%), while the lowest affected group was pink nylon attachments (21.56%).

Conclusions: PEEK attachments were the least affected by the denture cleanser but the most affected by insertion and removal cycles. Corega denture cleanser had no significant effect on nylon or PEEK attachments, whereas the insertion-removal cycle had a significant effect on both attachment systems.

Purpose: Interproximal contact loss (ICL) is considered a prevalent complication for a tooth abutting an implant restoration. While numerous potential causes for ICL have been presented, there is no consensus. A review of the current literature with a focus on possible risk factors was performed.

Materials and methods: A PubMed search using keywords "implant OR dental implants OR implant supported prosthesis AND proximal contact loss OR ICL OR loss of interproximal contact OR open contact OR interproximal open contact OR adjacent natural teeth" resulted in 81 citations, 9 of which were relevant to the focus question. Additional references were culled from the reference lists in the identified articles. Systematic reviews, case series, and case reports were reviewed with a focus on causation, association, or correlation.

Results: Eight systematic reviews and 14 case series were reviewed. The prevalence of ICL has been reported to be as low as 16% and as high as 66%. ICL was more common on the mesial side of implants and when a tooth abuts a splinted implant restoration. The absence of a uniform definition to accurately describe an interproximal (IP) contact and an open IP contact is demonstrated in the literature. A lack of standardized measurement strategies that relate to a needed consensus definition further exacerbates the broad range of reported results regarding ICL. The lack of controls for almost all the ICL literature makes it difficult to draw conclusions and comparisons to unrestored, natural tooth IP contacts and the prevalence of ICL in this patient population. As a result, the available studies are inadequate to support a causal theory and the potential risk factors associated with ICL.

Conclusions: There is a large range of reported prevalence for IP contact loss. ICL is more common when a natural tooth abuts a splinted implant restoration. ICL is more common on the mesial, as opposed to the distal, of an implant retained restoration. Consensus in the definition and measurement strategies for ICL needs to be established to provide standardized terminology and methodology. Potential risk factors such as occlusion, restorative material, and tooth contact area need to be investigated.

Patients with Down syndrome (DS) have a high incidence of obstructive sleep apnea (OSA) due to hypotonia, weight, underdeveloped midface, and relative macroglossia. This article presents three cases of young adults with DS, who were diagnosed with mild to severe OSA and unable to tolerate positive airway pressure therapy. These patients have been successfully treated with a custom-made mandibular advancement device (MAD) or dual treatment with MAD and bi-level positive airway pressure (PAP) therapy. The baseline apnea-hypopnea index (AHI) of the three patients were 15.5/h, 31.8/h, and 41.3/h. The follow-up AHI after the application of MAD in three patients was 25/h (13 months after), 6/h (ODI 4%, 57 months after), and 21.8/h (21 months after), respectively. The application of MAD to treat OSA in patients with DS is a reasonable alternative when patients refuse PAP therapy. Although MAD might be less effective than PAP therapy, significant symptomatic improvement could be found in patients with DS after oral appliance therapy. The combination of MAD and PAP can decrease the PAP pressure and therefore improve adherence. This is the first case report to show that young adult patients with DS can successfully benefit from oral appliance therapy for OSA treatment.

Purpose: This study aimed to evaluate the accuracy and precision of two smartphone colorimeter apps, Color Grab, and Color Picker, in measuring forehead skin color and to compare their readings with those from a spectrophotometer.

Materials and methods: Fifty participants (26 males, 24 females; median age 23 years, range 21-45) were included. Using a smartphone camera, images of forehead skin were captured, and CIELAB color values were reported by both apps. Measurements from a reference spectrophotometer (MiniScan EZ 4500L, 45°/0° geometry) served as the gold standard. Trueness and precision were assessed using CIELAB and CIEDE2000 formulas. Statistical analyses included one-way ANOVA and Mann-Whitney tests, with significance at p < 0.05.

Results: Both apps showed comparable accuracy in capturing skin color, with absolute trueness (ΔE_Abs) for Color Grab at 7.59 (CIEDE2000) and Color Picker at 7.65. Relative trueness (ΔE_Rel) was 3.79 for Color Grab and 3.70 for Color Picker. Precision (MCDM) demonstrated significant differences between the apps: Color Grab at 1.34 (CIEDE2000) compared to Color Picker at 0.96 (p < 0.0001).

Conclusion: While smartphone apps may not match the accuracy of spectrophotometers, they offer valuable alternatives for color matching in maxillofacial prostheses. Future studies should focus on minimizing systematic errors related to environmental factors and camera settings to enhance measurement accuracy.

Purpose: To evaluate the impact of varying concentrations of 3 mol% yttria-stabilized tetragonal zirconia polycrystalline ceramic (3Y-TZP) nanoparticles on mechanical properties of three-dimensional (3D)-printed resins in stereolithography (SLA) technology.

Materials and methods: A total of four groups (n = 6) of specimens were printed. Pure 3D-printed resin was used as the control group (0 wt%). For the experimental groups, modified 3Y-TZP nanoparticles were dispersed into 3D-printed resin at 1, 3, and 5 wt% concentrations to fabricate nanocomposites. Mechanical tests, including degree of conversion (DC), flexural strength, flexural modulus, fractography, and hardness, were evaluated and analyzed by one-way analysis of variance followed by the Games-Howell post-hoc test or Tukey post-hoc test (α = 0.05).

Results: The DC of the control group showed the lowest value (p < 0.0001). The DC values peaked at the 5 wt% group, with no significant difference between the 3 wt% group. The flexural strength and modulus of the experimental groups were significantly higher than those in the control group. The addition of 1 and 3 wt% 3Y-TZP nanoparticles significantly improved the flexural strength and modulus (p < 0.05), while 5 wt% resulted in a significant decrease. The 1 wt% group showed the lowest hardness value. Maximum hardness value was observed in the 3 wt% group (p < 0.05). No significant difference was observed between the control and 5 wt% groups (p = 0.428).

Conclusion: Optimal mechanical properties were obtained with the 3 wt% group, indicating its potential as a dental material in clinical application.

Purpose: This study aims to evaluate the fracture strength of three-unit, implant-supported fixed dental prostheses (FDPs) constructed from 3D-printed resin. It compares structures with and without fiber-reinforced composite (FRC) frameworks under conditions that mimic artificial aging.

Materials and methods: Forty FDPs were fabricated and divided into two groups: monolithic (n = 20) and bi-layer (n = 20). The monolithic group (MG) consisted entirely of FDPs made from 3D-printed resin for permanent restorations, while the bi-layer group (BG) featured FDPs with an FRC framework veneered with the same 3D-printed resin. Each group was subdivided into two subgroups: one subjected to artificial aging (MTG, n = 10; BTG, n = 10), and the other served as the baseline control (n = 10). All subgroups underwent a mechanical bending test, applying a single load to failure using a universal testing machine.

Results: There was a statistically significant difference in fracture strength due to the presence of the FRC framework (p < 0.01). The framework became the FDP more resistant to load. The mean load to failure and standard deviations were as follows: MG 406.59N (±33.84), MTG 286.20N (±152.15), BG 1142N (±162.88), and BTG 945N (±211.52). Although no statistical differences in strength were observed between aged and nonaged subgroups, variations in failure patterns emerged, with the BG and BTG groups showing a predominance of failures compared to the MG.

Conclusions: The inclusion of an FRC framework significantly enhanced the fracture strength of the FDPs. While the aging protocol did not alter the strength, failures predominantly occurred in the 3D-printed resin superstructure at the connectors. The highest rate of fractures occurred in the premolar connector.

Purpose: To measure the effect of daily immersion in varying beverages (distilled water, tea, carbonated beverage, and orange juice) on surface roughness and color stability of 3D-printed denture base resins.

Materials and methods: 160 acrylic resin discs (15 × 2.5 mm) were made from heat-polymerized (HP), and 3D-printed resins (FormLabs, ASIGA, and NextDent). Resin discs (N = 40) were immersed in different solutions (distilled water, tea, carbonated beverage, or orange juice; (n = 10/group)). Surface roughness (R_a, µm) was measured initially (T₀), 6 months post immersion (T₁), and 12 months post immersion (T₂) using a non-contact profilometer. Color change (∆E₀₀) was calculated using CIEL2000 at T₁ and T₂ using a spectrophotometer. The data were analyzed using Mann-Whitney U test and Kruskal-Wallis test in addition to general linear modeling (α = 0.05).

Results: Significant differences in surface roughness (R_a) were found between the baseline and immersion in distilled water, carbonated beverage, and orange juice (p < 0.05). HP resin showed increased roughness with all immersion solutions compared to T₀ with the highest value seen at T₁ with tea. ASIGA resin had the highest mean R_a of 1.78 (0.43) after carbonated beverage immersion, while FormLabs resin had the lowest mean R_a of 0.88 (0.06) after distilled water immersion. Tea immersion did not significantly affect R_a among the resins (p > 0.05). Noticeable color changes were observed after immersion in tea, carbonated beverage, and orange juice. All resins exceeded perceptibility and acceptability thresholds at T₁ and T₂. The combined effect of time and resin on color change was statistically significant (p < 0.001), while the combined effects of time/immersion solution, immersion solution/resin, and immersion solution/resin/time were not.

Conclusion: Carbonated beverage, tea, and orange juice increase the surface roughness of 3D-printed resins. Tea, carbonated beverage, and orange juice resulted in noticeable color changes of HP and 3D-printed denture base resins and this change was time-dependent.

Purpose: To assess the flexural strength (FS), surface roughness, and color stability of additive manufactured (AM) and subtractive manufactured (SM) denture teeth materials, as well as the effect of thermocycling on these properties.

Materials and methods: Eighty strips (20/material type; 64×10×3.3 mm) and 60 discs (15/material type; 12×4 mm) were fabricated from four different denture teeth materials (Straumann, Flexcera, Ivoclar, and Candulor). The specimens were divided into two subgroups (nonthermal cycled and 5000 thermal cycled,10 per subgroup), and subjected to a 3-point test for FS using a universal testing machine at a crosshead speed of 5.0 mm/min. Surface roughness (R_a, µm) and color differences (ΔE₀₀) of disc specimens were measured before and after thermocycling using a noncontact optical profilometer and a spectrophotometer, respectively. The CIEDE2000 formula was used to calculate the color differences (ΔE₀₀) before and after thermocycling. Data were analyzed using 2-way ANOVA followed by post hoc multiple comparison tests (α = 0.05).

Results: There was no significant difference in flexural strength between nonthermal cycled SM materials (p = 0.15), which were significantly higher than AM materials (p < 0.001). The flexural strength values of all tested materials were significantly reduced after thermocycling (p < 0.05). The material type had a significant effect on the R_a values (p < 0.001), whereas thermocycling did not (p = 0.81). After thermocycling, all materials exhibited color changes lower than the clinical perceptible threshold (ΔE₀₀ = 2.7).

Conclusions: Thermocycling decreased the FS of denture teeth materials manufactured with AM and SM, but did not affect the surface roughness. The FS values of SM groups were significantly higher than AM materials, irrespective of thermocycling. No clinically significant color changes of the denture teeth material were noted.