Impact of adding zirconium oxide nanoparticles to the 3D printable acrylic resin base material for implant-retained overdentures: A clinical comparative parallel study.

STATEMENT OF PROBLEM: Three-dimensionally (3D) printed acrylic resin base materials have been adopted in prosthetic dentistry. However, their mechanical and biological properties require improvement. PURPOSE: The purpose of this clinical study was to evaluate the effect of adding zirconium oxide nanoparticles to a 3D printable acrylic resin base material for a 2-implant-retained complete mandibular overdenture in terms of peri-implant tissue health, surface roughness, and biofilm formation. MATERIAL AND METHODS: Twenty edentulous patients were enrolled in this clinical parallel study. All patients received maxillary complete dentures opposing a 2-implant-retained mandibular overdenture. The participants were randomly divided into 2 equal groups according to the mandibular overdenture base material, nonmodified 3D printable acrylic resin (control group) or 3D printable acrylic resin base material modified with 3.0 wt% zirconium oxide nanoparticles (study group). Peri-implant tissue health and surface roughness were measured immediately at the insertion of the mandibular overdenture (T0), after 3 months (T1), and after 6 months (T2). Microbiological assessment of the denture base was done after 1 week, 1 month, 3 months, and 6 months of overdenture use. The data were analyzed using a statistical software program. The Wilcoxon signed-rank test, paired t test, and Fisher exact test were used to compare distributed data. The Mann Whitney U test and repeated measures ANOVA test were used to compare distributed data at different times (α=.05). RESULTS: The gingival index (GI), plaque index (PI), probing depth (PD), and surface roughness values at the baseline, 3 months, and 6 months were statistically higher with the nonmodified compared with the modified group (P=.001). Regarding the microbiological analysis, the nonmodified group also had a statistically higher mean bacterial and Candida albicans count than the modified group (P<.05). No significant increase in the bacteria was found in the nonmodified group with time (P=.252), but, for the modified group, a statistically significant decrease in bacteria count was found with time (P<.001). CONCLUSIONS: Adding zirconium oxide nanoparticles to a 3D printable acrylic resin base material was found to be promising. This addition improved the peri-implant tissue health and decreased surface roughness and biofilm formation.

Surface hardness and wear resistance of prefabricated and CAD-CAM milled artificial teeth: A cross-over clinical study.

PURPOSE: To clinically evaluate the surface roughness and wear resistance of prefabricated and CAD-CAM milled acrylic resin teeth for complete dentures. MATERIALS AND METHODS: In a cross-over study design, 10 completely edentulous patients were randomly included in this study and given two complete dentures. The first complete denture was made using prefabricated teeth, while the second was constructed using CAD-CAM milled teeth. Following insertion (T0), 3 months (T3), and 6 months (T6), the complete dentures were scanned. Utilizing 3D surface super-imposition techniques, the vertical (2D wear), and volumetric (3D wear) material loss were measured. The hardness of the teeth was evaluated at the time of denture insertion (T0) and then after 6 months (T6) of denture insertion by digital Vickers hardness tester. Statistical analysis was done using SPSS software. Paired groups were compared by paired t-test. Also, a repeated measure test was used. The significant difference was considered if p ≤ 0.05. RESULTS: The time of denture function was linearly correlated with the wear of the prefabricated and CAD-CAM milled denture tooth. Prefabricated acrylic teeth had significantly more vertical and volumetric wear after 3 and 6 months, compared to CAD-CAM milled denture teeth where p-values were 0.01, 0.009, 0.003, and 0.024, respectively. Additionally, CAD-CAM milled teeth displayed significantly higher hardness values than prefabricated teeth both before and after 6 months of use where p-values were 0.001. After 6 months, all studied teeth showed a decrease in their hardness. CONCLUSIONS: In terms of wear resistance and surface hardness, CAD-CAM milled acrylic resin teeth were superior to prefabricated acrylic resin artificial teeth once the complete denture functions.

Patient satisfaction and oral health-related quality of life for four implant-assisted mandibular overdentures fabricated with CAD/CAM milled poly methyl methacrylate, CAD/CAM-milled poly ether ether ketone, or conventional poly methyl methacrylate: A crossover clinical trial.

BACKGROUND: New materials for overdenture base construction were evolved. Thus, more clinical trials are needed to validate these materials. OBJECTIVE: This study aimed to compare the difference between CAD/CAM-milled poly methyl methacrylate (PMMA), poly ether ether ketone (PEEK) and conventional mandibular implant-assisted overdentures regarding patient satisfaction and oral health-related quality of life (OHRQL). METHODS: This randomised, crossover, clinical study included 18 completely edentulous subjects rehabilitated with three mandibular implant-assisted overdentures with three different denture base materials opposing a maxillary single denture. These materials were as follows: CAD/CAM-milled PMMA, CAD/CAM-milled PEEK and conventional PMMA. Every participant first received each mandibular overdenture in a random manner. After 6 months of each overdenture use, patient satisfaction and oral health-related quality of life were assessed using visual analogue scale (VAS) and Oral Health Impact Profile (OHIP-EDENT-19), respectively, and then crossover to other groups was done. The same was repeated to the last group. Comparison of VAS and OHIP-EDENT-19 between groups was done using Kruskal-Wallis test followed by Bonferroni test. RESULTS: Regarding all the VAS items, there were statistically significant higher scores for CAD/CAM-milled PMMA and PEEK than conventional PMMA base except for speech, aesthetic and smell. Regarding OHIP-EDENT-19, many items revealed statistically lower problem scores for CAD/CAM-milled PMMA, and CAD/CAM-milled PEEK than conventional PMMA base except psychological discomfort, psychological disability and social disability. CONCLUSION: Within the limit of this study, CAD/CAM-milled PMMA and CAD/CAM-milled PEEK were recommended as implant-assisted overdenture bases as it revealed higher patient satisfaction and better oral health-related quality of life in comparison with conventional PMMA implant-assisted overdenture.

Efficacy of stabilisation splint and low-level laser therapy for patients with chronic closed lock from non-reducible displaced temporo-mandibular joint discs: A parallel randomised clinical trial.

BACKGROUND: Stabilisation splint therapy (SST) and low-level laser therapy (LLLT) are effective-invasive treatment for temporo-mandibular disorder (TMD) patients. However, the specific efficacy of each therapy in patients with chronic closed lock (CCL) from temporo-mandibular joints (TMJ) disc displacement without reduction (DDwoR) remains unknown. OBJECTIVES: The aim of this study was to assess and compare the efficacy of SST and LLLT alone or in combination in patients with CCL from TMJ DDwoR. METHODS: This parallel randomised clinical trial included 42 patients who were diagnosed with CCL from TMJ DDwoR. Patients were allocated equally and randomly into three treatment groups: group I received combined SST and LLLT, group II received LLLT and group III received SST. Maximum mouth opening (MMO), visual analogue scale (VAS), muscle and joint palpation scores and time required to achieve normal state were evaluated at baseline, 1, 2, 4 weeks, 3 and 6 months after the intervention. Data were collected and analysed using SPSS software. RESULTS: Regarding MMO and VAS, a statistically significant improvement was found between group I versus group II and versus group III at all evaluation times. Regarding muscle and joint palpation scores, a statistically significant difference was found between group I versus group III, while non-significant difference was found between group I and group II. A statistically significant faster improvement was found in group I versus group III and versus group II. CONCLUSION: All treatment modalities can be effective in management of CCL from a TMJ DDwoR cases, but the combined SST and LLLT group seems to provide the best and quickest improvement. CLINICAL TRIAL REGISTRATION NUMBER: NCT05548894.