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

Alveolar bone morphology drives the edentulous patient's rehabilitation. In edentulism, maxillary resorption is often in three vectors: superiorly, medially, and posteriorly, leading to a prosthetically unfavorable pseudo-class III ridge relationship. Longstanding edentulism, especially in the context of ill-fitting dentures, can result in severe maxillary atrophy. Rehabilitation of the severely atrophic maxilla remains a challenge, frequently requiring extensive bone grafting procedures in combination with endosseous dental implants. Graftless options, using longer endosseous and/or tilted dental implants placed into the nasal, pyriform rim, pterygoid process, and zygomatic bone, have been developed to solve this treatment dilemma. These options have specific patient anatomy limitations, can be technique sensitive, and can result in increased patient morbidity. Digitally planned, custom-milled, and rigidly fixated subperiosteal implants offer a recently introduced immediate fixed option when conventional solutions fail or are contraindicated. Cone-beam computed tomography (CBCT) and computer-aided design and computer-aided manufacturing (CAD-CAM) redefine a controversial 70-year-old concept, using prosthodontic reverse-engineering to offer stability, reduced morbidity, and improved patient satisfaction. Long-term follow-up for the use of this technique in fixed definitive restorations is not available at this time.

Rigidly fixated custom subperiosteal implants (SPIs) have been reported in the literature for fixed retention of a prosthesis when there is limited or absent alveolar bone for placement of endosteal implants. Advances in digital technology and manufacturing have provided excellent adaptation and stability for this latest generation of SPIs, and the applications for this technique extend beyond fixed restorations of the partially or completely edentulous arch. In this case report, a modern patient-specific SPI was utilized to retain a surgical obturator without additional interdental or interosseous wiring.

This paper presents a digital technique for creating a dynamic edentulous virtual patient using a 3-dimensional (3D) printed multifunctional intraoral device. By integrating custom impression trays, occlusal rims, a gothic arch tracer, facial scan markers, and an optical jaw tracking device, this multifunctional device allows capturing essential diagnostic datasets in one visit and enables unified alignment within computer-aided design (CAD) software. This approach addresses current key limitations, such as the lack of stable tracking references and difficulties in aligning intraoral and facial scans.

Purpose: The present study aimed to identify and characterize the prosthetic complications associated with the use of the Locator system in implant-supported overdentures. The objectives were to determine their prevalence, evaluate the clinical management of overdentures with Locator abutments in relation to retention loss, and analyze possible associations between these complications and relevant clinical variables.

Materials and methods: A retrospective observational study was conducted at the University Dental Clinic of Universidad Europea de Valencia, including patients over 18 years of age treated between 2016 and 2024 with implant-supported overdentures using the Locator system. A total of 41 patients with 46 overdentures were analyzed. Data collection was based on digital clinical records, and statistical analysis was performed using SPSS software, employing both descriptive and inferential tests.

Results: Of the overdentures analyzed, 69.57% presented at least one prosthetic complication. The most frequent issues were mucosal ulcers and mechanical failures such as loss of the metal housing, loosening or loss of the Locator abutment, and fracture of prosthetic components. Retention loss was the primary reason for clinical intervention, with replacement of retentive inserts being the most common procedure, especially during the first year after placement.

Conclusions: Prosthetic complications in overdentures with the Locator system are common and require early clinical attention. No significant associations were found with clinical variables such as age, sex, treated arch, or number of implants. Prospective studies with larger sample sizes are recommended to identify risk factors and optimize maintenance protocols.

Purpose: This systematic review and meta-analysis evaluated the bond strength effectiveness of a self-etching ceramic primer, specifically Monobond Etch & Prime (MEP), compared to hydrofluoric acid with silane (HF+S) in feldspathic and leucite-reinforced dental glass-ceramics (DGCs).

Materials and methods: This study followed PRISMA-p guidelines and was registered in the Open Science Framework (DOI: 10.17605/OSF.IO/MERJU). Searches were conducted in PubMed/Medline, Scopus, Embase, Web of Science, and gray literature through October 2024. In vitro studies comparing MEP and HF+S without language or year restrictions were included. Risk of bias was assessed using RoBDEMAT. Meta-analyses considered bond strength test methods and aging protocols.

Results: Sixteen studies were included from 1322 records (k = 0.91). Under immediate conditions, no significant differences were observed between MEP and HF+S for feldspathic (p = 0.21) and leucite-reinforced (p = 0.96) DGCs, indicating comparable short-term bond strength performance. After aging, no significant differences were found for feldspathic DGCs (p = 0.14), while HF+S showed higher strength in leucite-reinforced (p < 0.00001) DGCs. Overall, findings remain inconclusive for long-term performance due to high methodological heterogeneity (I² > 50%), variations in aging protocols, reliance on in vitro-only studies, insufficient reporting of randomization, and absence of operator blinding.

Conclusion: Under immediate conditions, MEP demonstrates bond strength comparable to HF+S, with the advantage of a simplified and safer application. Long-term performance remains uncertain due to methodological heterogeneity and in vitro-only evidence, highlighting the need for standardized protocols and clinical validation.

Purpose: The purpose of this in vitro study was to evaluate the effect of the angulation degree of multi-unit abutment (MUA) on the prosthetic screw-joint stability using a reverse torque test of the prosthetic screw and a pull-out test of the bonded coping.

Materials and methods: Thirty specimens with a two-implant segmental portion of an implant-supported fixed dental prosthesis design were prepared. Titanium copings (Variobase; Straumann USA) were cemented to the zirconia specimens (ZirCAD; Ivoclar Vivadent) using RelyX Universal Cement and Scotchbond Universal Plus Adhesive (3 M ESPE). The groups were defined as follows: Group S-S: straight implant + 0° MUA and straight implant + 0° MUA, used as the controls; Group S-17: straight implant + 0° MUA and 17° angulated implant + 17° MUA; and Group S-30: straight implant + 0° MUA and 30° angulated implant + 30° MUA. The initial torque value and initial reverse torque values of prosthetic screws were recorded using a digital torque gauge (Model HTGS-15; Imada Inc.). Zirconia specimens and cemented titanium copings were treated with thermal cycling (5000 cycles of 5°C-55°C, dwelling time 20 s). After this limited thermal cycling, all prosthetic screws were replaced with new screws to connect the zirconia plate to MUAs with tightening to 15 Ncm. All specimens were then subjected to masticatory simulation using cyclic loading treatment (300 N, 1.5 Hz in a 37°C water bath for 5000 cycles). At the end of the cyclic loading, final reverse torque values were recorded. A pull-out test of the cemented coping was conducted using a universal testing machine with a crosshead speed of 5 mm/min for all specimens. Failure patterns of the titanium copings and damage to the prosthetic screws were examined under an optical microscope. Mixed-effects linear modeling and estimated marginal means were used to analyze torque value changes. One-way ANOVA was used to analyze retentive force values from the pull-out test at α = 0.05.

Results: The torque value loss percentage of individual abutments ranged from 16.43% to 28.78%. There was a significantly higher torque value loss of Group S-30 when compared to Group S-S before cyclic loading (p = 0.01). After cyclic loading treatment, there is an increased torque value loss in Group S-S compared with before cyclic loading (p = 0.02). No statistically significant differences in pull-out force were observed among groups (p = 0.689). Debonding of titanium coping occurred in Group S-S only, while prosthetic screw deformations occurred 100% in Group S-30.

Conclusions: Prosthetic screw loosening was expected to occur at the same rate in all tested groups after cyclic loading treatment. However, when complications such as debonding of titanium coping or prosthetic screw fracture occurred, the modes of failure differed in each group.

Purpose: Achieving optimal surface roughness and flexural strength for zirconia, regardless of whether it is produced using additive or subtractive manufacturing, remains a challenge. Moreover, the effect of polishing protocol timing, relative to sintering, on those properties is not comprehensively known yet. The purpose of the study was to evaluate the effect of the timing of polishing, considering the sintering stage, on the surface roughness and flexural strength of additively or subtractively manufactured 3Y-TZP zirconia.

Materials and methods: Disc-shaped (n = 40) and bar-shaped (n = 64) zirconia specimens were either subtractively manufactured (SM) or additively manufactured (AM) for surface roughness measurements and flexural strength tests, respectively. Specimens were polished following different protocols depending on timing: before sintering, before and after sintering, after sintering, and some received no polishing. Surface roughness was measured with a noncontact optical profilometer at each stage. Flexural strength was assessed using a three-point bending test according to ISO 6872:2015. The data were analyzed using two-way ANOVA and post hoc tests to evaluate the effects of material type and polishing protocol on the surface roughness and flexural strength (α = 0.05).

Results: The lowest R_a values were recorded when polishing was done before and after sintering (AM: 0.22 ± 0.03 µm; SM: 0.18 ± 0.02 µm) (p ≤ 0.05). AM zirconia specimens demonstrated a greater reduction in surface roughness compared to SM across all polishing protocols (p < 0.001). The highest flexural strength was recorded in specimens polished before and after sintering in the AM group (1049.98 ± 71.61 MPa) (p ≤ 0.05).

Conclusions: Polishing performed both before and after sintering enabled clinically acceptable surface roughness for AM zirconia. In all polished specimens, AM specimens polished before and after sintering had the highest flexural strength.

Purpose: This study aimed to evaluate the effect of internal wall inclination of Morse taper dental implants on the stress distribution on the peri-implant area, using the photoelasticity method.

Materials and methods: The analysis of stress was performed in three groups (EH: External Hexagon, MT: Morse Taper, GM: Grand Morse), dividing the photoelastic models between implants with external (HE) and internal (MT and GM) connections. Two different inclinations of the internal walls were assessed for implants with internal connection: MT: 11.5° and Grand Morse: 16°. The implant-supported prostheses were submitted to 100 N axial and oblique loads within the photoelastic models. The qualitative analysis was performed by describing the fringes formed in the photoelastic block. The quantitative analysis of the stresses was performed using the table recommended by the ASTM D4093-95 standard, which relates the colors of the isochromatic fringes to the numerical stress values.

Results: The results showed that the HE had a greater concentration of stresses in the apical region, while the implants with internal connections (MT and GM) showed a similar biomechanical pattern of stress distribution, regardless of the inclination of the internal walls.

Conclusions: Increasing the internal wall inclination from 11.5° to 16° did not yield any additional biomechanical advantages in implant-supported rehabilitation.