Evaluation of marginal/internal fit of fixed dental prostheses after digital, conventional, and combination impression techniques: A systematic review.

Advances of digital technology are rapidly adopted in dental practice. This systematic review aimed to collect evidence on the accuracy of fit of different types of fixed dental prostheses (FDPs) fabricated through digital, conventional, or combination impression techniques. Data collection was based on the guidelines of the preferred reporting items for systematic reviews and meta-analyses (PRISMA). Two databases (PubMed, Scopus) were searched for articles in English published between 2010 and 2021 resulting in 480 articles. Of those, 35 studies fulfilled the inclusion criteria. These articles referred to three groups of materials/techniques including all-ceramic (zirconia; lithium disilicate) and porcelain-fused-to-metal (PFM) restorations. Results showed clinically acceptable marginal fit (< 120 µm) for all materials and impression techniques. Α fully digital workflow appears more promising for the construction of short-span zirconia FDPs. Nevertheless, most articles evaluated marginal/internal fit of single crowns or short-span FDPs in vitro, while clinical data are limited for long-span FDPs. The necessity for gingival retraction remains a major drawback of all impression techniques, increasing procedural time and patient discomfort. Besides, factors related to the fabrication process, including milling and 3D printing of working models significantly influence the outcome. Overall, there still some way to go before digital technology can be incorporated in complex treatment plans in prosthodontics.

Proof of Concept for the Detection of Local Pressure Marks in Prosthesis Sockets Using Structural Dynamics Measurement.

The wear comfort of a prosthesis is of great importance for amputee patients. The wear comfort can be affected by changes in the interface between the residual limb and prosthesis socket, which can be caused by time-dependent volume fluctuations of the tissue, leading to unwanted local pressure marks. The basis to ensure time-independent wear comfort of a prosthesis is to identify these changes. Common techniques for identifying these variations have a negative impact on the sensitive interface between the residual limb and prosthesis. The following paper contains a proof of concept for the detection of local pressure marks without affecting the described interface using structural dynamics measurements, exemplarily shown at a prosthetic socket for transfemoral amputees in a test bench scenario. The dynamical behaviour of the investigated system is analysed in the form of frequency response functions acquired for different pressure locations and preloads using an impact hammer for excitation and a triaxial acceleration sensor. The frequency response functions show major changes for the various boundary conditions with respect to their frequency-dependent compositions. The results demonstrate how the utilised method enables the identification of changes in local pressure marks regarding the variation of position and magnitude.

New mobile-bearing TKA with unique ball and socket post-cam mechanism offers similar function and stability with better prosthesis fit and gap balancing compared to an established fixed-bearing prosthesis.

PURPOSE: A mobile-bearing (MB) posterior-stabilized total knee arthroplasty (TKA) system with ball and socket post-cam mechanism has been developed with the aims of better prosthesis fit and enhanced stability. However, the data are limited to compare its clinical outcomes with an already established fixed-bearing (FB) implant design. METHODS: This is a prospective randomized study comparing 260 patients in the MB group and 133 patients in FB group with a minimum 2 years of follow-up. Intraoperative variables, post-operative functional outcomes and incidence of adverse events were compared. RESULTS: MB group showed better prosthesis fit as the incidence of over-hang of femoral component at junction (medial: 1% vs. 5% and lateral: 2% vs 4%, p < 0.001) and trochlea (medial: 2% vs 30%, p = 0.042 and lateral: 13% vs 21%, p = 0.015) was less than FB group. MB group also showed better gap balancing as the incidence of medio-lateral gap difference more than 2 mm was less in flexion (2.3% vs. 16%, p < 0.001) and extension (3.1% vs. 9.8%, p = 0.005). Post-operative functional outcomes and incidence of adverse events showed no difference between the two groups at 2 years. CONCLUSIONS: New MB design offers similar functional outcomes and stability along with better intraoperative prosthesis fit and gap balancing compared to an established fixed-bearing design. Hence, this new MB design could be an alternative prosthesis of choice for posterior-stabilized TKA. LEVEL OF EVIDENCE: I.

Evaluation of the Impact of Digital Dentistry on the Precision of Implant Placement and Prosthesis Fabrication: An In-Vitro Study.

BACKGROUND: Digital dentistry has revolutionized the field of implant dentistry, offering enhanced accuracy and precision in implant placement and prosthesis fabrication. This study aims to evaluate the effect of digital dentistry on the accuracy of implant placement and prosthesis fit through a comprehensive in-vitro assessment. METHODS: In this in-vitro study, a Digital Dentistry Group and a Conventional Group were compared regarding implant placement accuracy and prosthesis fit. Measurements of coronal deviation, apical deviation, global deviation, angulation deviation, and depth deviation were obtained for implant placement accuracy, while marginal fit and internal fit were assessed for prosthesis fit. Statistical analysis was performed to determine significant differences between the two groups. RESULTS: The Digital Dentistry Group demonstrated significantly lower values of coronal deviation, apical deviation, global deviation, angulation deviation, and depth deviation compared to the Conventional Group (p < 0.001). Similarly, the Digital Dentistry Group exhibited superior marginal fit and internal fit (p < 0.001) when compared to the Conventional Group. CONCLUSION: This in-vitro study provides evidence supporting the superior accuracy of implant placement and improved prosthesis fit achieved through digital dentistry techniques. The use of intraoral scanners, computer-aided design/computer-aided manufacturing (CAD/CAM) systems, and three-dimensional (3D) imaging enables precise digital impressions, virtual planning, and custom-made prostheses with superior fit and esthetics. Incorporating digital dentistry into clinical practice can enhance treatment outcomes and patient satisfaction in implant dentistry.

Exploring the Impact of 3D Printing Technology on Patient-Specific Prosthodontic Rehabilitation: A Comparative Study.

Introduction: The rapid advancement of 3D printing technology has opened new avenues for patient-specific prosthodontic rehabilitation. This study aimed to explore the impact of 3D printing technology on prosthodontic outcomes and patient satisfaction through a comparative analysis. Materials and Methods: A total of 100 patients requiring prosthodontic rehabilitation were recruited for this study. The patients were randomly divided into two groups: the experimental group, where 3D printing technology was utilized for the fabrication of patient-specific prostheses, and the control group, where conventional fabrication techniques were employed. Various parameters were assessed, including prosthesis fit, occlusion, esthetics, and patient-reported outcomes such as comfort and satisfaction. Digital measurements and subjective evaluations were conducted to compare the outcomes between the two groups. Statistical analysis was performed using appropriate tests. Results: Preliminary findings indicated that the use of 3D printing technology in prosthodontic rehabilitation resulted in superior prosthesis fit, enhanced occlusal stability, and improved esthetics compared to conventional methods. Moreover, patients in the experimental group reported higher levels of comfort and overall satisfaction. The advantages of 3D printing technology were observed across different types of prosthodontic restorations, including crowns, bridges, and dentures. These results highlight the potential of 3D printing technology to revolutionize patient-specific prosthodontic rehabilitation. By facilitating precise fabrication, customization, and improved functional outcomes, 3D printing can enhance the overall quality of prosthodontic care. Further long-term studies are warranted to validate these findings and explore the cost-effectiveness and long-term durability of 3D-printed prostheses. Conclusion: In conclusion, this study demonstrates that the integration of 3D printing technology in patient-specific prosthodontic rehabilitation holds great promise for achieving optimal functional and esthetic outcomes. The findings contribute to advancing prosthodontic practices and provide valuable insights for clinicians and researchers seeking to incorporate this innovative technology into their treatment protocols.

Biomedical and psychosocial factors influencing transtibial prosthesis fit: a Delphi survey among health care professionals.

PURPOSE: We aimed to reach consensus among professionals caring for prosthesis users, on definitions of biomedical and psychosocial factors, to assess their influence on fit of transtibial prosthesis and to identify new factors. METHOD: A three-round, internet-based, Delphi survey was conducted among experts recruited via the Dutch National Amputee and Prosthesis Work Group. The main outcome measure was consensus among care professionals on statements concerning new and presented biomechanical and psychosocial factors that influence transtibial prosthesis fit. RESULTS: Fifty-four experts participated in the survey, and consensus was reached on 67% (46/69) of all statements. Consensus on statements relevant for good prosthesis fit was reached in most of the statements concerning psychosocial factors and on statements concerning the biomedical factors "prosthesis support and suspension". Least consensus was reached on statements concerning the biomedical factor "skin problems and pain in the residual limb". CONCLUSIONS: Biomedical and psychosocial factors influence transtibial prosthesis fit. Consensus was reached among care professionals in a majority of the presented statements concerning these factors. Implications for Rehabilitation Prosthesis fit and comfort is suboptimal in many prosthesis users. Both biomedical and psychosocial factors influence fit. Biomedical and psychosocial factors should be checked during transtibial prosthesis prescription to achieve and maintain an optimal fit. Consensus on many factors influencing prosthesis fit is achieved among care professionals. Consensus was largest regarding prosthesis support and suspension and least regarding skin problems and pain in the residual limb. This consensus contributes to systematic assessment of prosthesis fit.

Implant/abutment vertical misfit of one-piece cast frameworks made with different materials

This study compared vertical and passive fit of one-piece cast frameworks made with 3 different materials: commercially pure titanium (CP Ti - G1), cobalt-chromium alloy (Co-Cr - G2) and nickel-chromium-titanium alloy (Ni-Cr-Ti - G3). Fifteen frameworks were obtained simulating bars for fixed prosthesis in a model with 5 implants. The passive and vertical fit of the framework interface was measured using an optical microscope at ×30 magnification. Data were statistically analyzed by ANOVA and LSD tests (α=0.05). Mean and standard deviation values for passive fit and vertical fit were, respectively: G1 [472.49 (109.88) µm and 29.9 (13.24) µm], G2 [584.84 (120.20) µm and 27.05 (10.30) µm], and G3 [462.70 (179.18) µm and 24.95 (11.14) µm]. For vertical fit, there were no significant differences among G1, G2 and G3 (p=0.285). There were no significant differences for passive fit between G1 and G3 (p=0.844), but both differed significantly from G2 (p=0.028 and p=0.035, respectively), which showed the highest misfit values. It may be concluded that the vertical fit of frameworks was not affected by the tested materials, and that one-piece cast frameworks resulted in inadequate passive fit. The Co-Cr alloy presented the worst values for passive fit.

Este estudo tem como objetivo comparar o ajuste vertical e a passividade de infraestruturas em monobloco confeccionadas em 3 diferentes materiais: titânio comercialmente puro (Ti cp - G1), cobalto-cromo (Co-Cr - G2) e níquel-cromo-titânio (Ni-Cr-Ti - G3). Quinze infraestruturas foram obtidas simulando barras para próteses fixas em um modelo com 5 implantes. O ajuste vertical e a passividade da interface da infraestrutura foram medidos usando um microscópio óptico (30×). Os dados foram analisados estatisticamente por meio da ANOVA e teste LSD (α=0,05). A média dos valores e o desvio-padrão da passividade e do ajuste vertical estão apresentados respectivamente: Ti cp [472,49 (109,88) μm e 29,9 (13,24) μm], Co-Cr [584,84 (120,20) μm e 27,05 (10,30) μm], Ni-Cr-Ti [462,70 (179,18) μm e 24,95 (11,14) μm]. Para o desajuste vertical, não houve diferença significante entre o Ti cp e as ligas Co-Cr e Ni-Cr-Ti (p=0,285). Para passividade, não houve diferença significante entre Ti cp e Ni-Cr-Ti (p=0,844), mas ambos foram estatisticamente diferentes do Co-Cr (p=0,028 e p=0,035, respectivamente), o qual apresentou os piores resultados. Pode-se concluir que os materiais utilizados para confecção das infraestruturas não influenciaram o ajuste vertical e que infraestruturas fundidas em monobloco resultaram em inadequados ajustes passivos. A liga de Co-Cr apresentou os piores resultados para a passividade.