Search Results (58)

Background: Limited data are available regarding the mechanical performance of 3D-printed fixed partial dentures (FPDs) fabricated from different materials and connector geometries. The purpose of this in vitro study was to evaluate the influence of connector size and material type on the fracture resistance of three-unit posterior FPDs fabricated with two commercially available 3D-printable dental resins. Methods: A standardized metal model with two cylindrical abutments was used to design three-unit FPDs. A total of sixty samples were produced, considering three connector sizes (3 × 3 mm, 4 × 4 mm, and 5 × 5 mm) and two different resins: Temp Print (GC Corp., Tokyo, Japan) and V-Print c&b temp (Voco GmbH, Cuxhaven, Germany) (n = 10). Specimens were fabricated with a DLP printer (Asiga MAX UV), post-processed per manufacturer recommendations, and tested for fracture resistance under occlusal loading using a universal testing machine. Data were analyzed using nonparametric tests (Mann–Whitney U and Kruskal–Wallis; α = 0.05). Results: Significant differences were found between material and connector size groups (p < 0.001). Temp Print (GC Corp., Tokyo, Japan) demonstrated higher mean fracture loads (792.34 ± 578.36 N) compared to V-Print c&b temp (Voco GmbH, Cuxhaven, Germany) (359.74 ± 131.64 N), with statistically significant differences at 4 × 4 and 5 × 5 mm connectors. Fracture strength proportionally increased with connector size. FPDs with 5 × 5 mm connectors showed the highest resistance, reaching values above 1500 N. Conclusions: Both connector geometry and material composition significantly affected the fracture resistance of 3D-printed FPDs. Larger connector dimensions and the use of Temp Print (GC Corp., Tokyo, Japan) resin enhanced mechanical performance. Full article

Objective: This article presents a step-by-step digital technique for fabricating a 3D-printed surgical guide to assist in alveoloplasty for immediate denture placement. Methods: The workflow integrates intraoral scanning, virtual tooth extraction, digital soft tissue modeling, and additive manufacturing to produce a customized guide with an occlusal window and buccal slot, along with a verification stent. Results: This method ensures precise ridge recontouring and verification, enhancing surgical predictability and prosthetic fit. Conclusions: Unlike traditional surgical guides based on conventional casts or manual fabrication, this fully digital approach offers a practical and replicable protocol that bridges digital planning and clinical execution. By improving surgical precision, reducing operative time, and ensuring optimal denture fit, this technique represents a significant advancement in guided pre-prosthetic surgery. Full article

Background/Objectives: Recently, a novel magnetic attachment system was introduced to improve performance. Using the same technology, a new ultra-thin magnetic attachment (UTMA) was possible to produce. This study aimed to evaluate the feasibility of a magnet-retained telescopic partial denture (MTPD) utilizing the new UTMA. Methods: This in vitro study was performed using a titanium master model representing prepared lower first-premolar and second-molar abutment teeth. The inner crowns (ICs) (h: 4 mm, 4° taper) and four-unit MTPDs were fabricated via computer-aided design/computer-aided manufacturing (CAD/CAM) using zirconia. A Ø4 mm UTMA system (magnet assembly and keeper thickness: 0.6 mm and 0.4 mm, respectively) was cemented into the MTPD and the ICs using dual-cure resin cement. A load of 100 N was applied along with 10,000 insertion–removal cycles. The MTPD retentive force was measured before and after every set of 1000 cycles. Stability tests and surface morphology evaluations were conducted before and after cycling. A paired t-test (α = 0.05) was used to observe statistical differences. Results: The average retentive force of the MTPD was 6.86 ± 0.63 N and did not change significantly (p > 0.05) following the load cycles (6.66 ± 0.79 N). The MTPD demonstrated adequate stability under the occlusal load. Minimal deformations were observed on the magnet assemblies, keepers, ICs, and MTPD surfaces after the load tests. Conclusions: Considering the limitations of this study, an MTPD utilizing novel UTMAs fabricated through a digital workflow demonstrated adequate retentive force, stability, and durability for clinical use. Full article

Background/Objectives: Oral health is an important element of overall health and quality of life. However, few studies have evaluated the association between quality of life (QOL) and oral function, including tongue and lip movements. This study aimed to investigate the relationship between oral-related QOL and oral function, including tongue and lip movements, in independent elderly people. Methods: The participants were 143 community-dwelling elderly people in Taiwan (40 men, 103 women; 76.4 ± 6.4 years). We used the General Oral Health Assessment Index (GOHAI) to evaluate oral-related QOL. The items used to evaluate oral function were as follows: the speed of tongue movement from side to side, maximum tongue pressure, maximum lip pressure, the repeated saliva swallowing test, oral diadochokinesis (speed and dexterity when pronouncing /pa/, /ta/, and /ka/), and masticatory performance. In addition, we surveyed the number of remaining teeth, denture use, and awareness of problems at mealtimes. For the analysis, we compared the GOHAI score for each group, divided by cutoff values. Results: The univariate analysis revealed significant differences in the GOHAI score according to denture use, the number of remaining teeth, the state of occlusal support areas, the speed of tongue movement from side to side, oral diadochokinesis /ta/ and /ka/, and masticatory performance. The logistic regression analysis revealed that oral diadochokinesis /ka/ was a significant explanatory variable for low GOHAI scores (odds ratio = 13.145). Conclusions: Our results imply that lower oral-related QOL was associated with slow motor function at the rear area of the tongue. Full article

Complete dentures are exposed to complex masticatory forces that may lead to material fatigue and eventual structural failure. Occlusal relationships, such as eugnathic and progenic, influence the distribution of these forces significantly. Understanding their biomechanical impact is essential for improving denture design and longevity. The aim of this study was to evaluate the mechanical behaviour of complete dentures under bite loads in eugnathic and progenic occlusal relationships, using both experimental testing and numerical simulations. The focus was placed on identifying the conditions that lead to initial damage and the patterns of stress distribution. The material properties of the denture base and artificial teeth were determined through experimental tensile and compressive testing on cylindrical PMMA specimens. The denture geometry was acquired via 3D tomography based on impressions of an edentulous patient. Experimental testing of the denture bite was conducted to determine the force thresholds at which the initial cracks occur. Numerical simulations were carried out using finite element analysis at bite loads of 100 N and 200 N in both occlusal types, incorporating the obtained material parameters. The experimental results showed that the first signs of denture damage occurred at 6400 N in eugnathic occlusion and 7010 N in progenic occlusion. The numerical simulations confirmed that, during occlusion, the pressure is redistributed across multiple contact points, with a broader distribution reducing the localised stress. This redistribution was more efficient in eugnathic occlusion, which reduced the risk of longitudinal cracking in acrylic teeth. In contrast, progenic occlusion showed higher susceptibility to fractures within the acrylic denture base, particularly between adjacent teeth. Both the experimental and numerical approaches demonstrated that occlusal relationships affect the mechanical resilience of complete dentures directly. The findings highlight that eugnathic occlusion offers biomechanical advantages in stress distribution, potentially reducing the risk of fracture. Incorporating occlusal analysis into denture design protocols can enhance clinical outcomes and improve prosthetic longevity. Full article

Background: Mandibular movement is inherently complex, involving both lateral and vertical components. In older adults, this complexity is compounded by diminished neuromuscular coordination and reduced proprioceptive feedback, often impairing effective mastication. Objectives: This study aimed to review dental literature on the influence of masticatory parameters in the formation of wear facets on acrylic resin denture teeth. Methods: A targeted literature review was conducted, analyzing peer-reviewed studies from 1991 to 2024 through PubMed and Scopus. The review focused on masticatory parameters, age-related neuromuscular adaptations, chewing patterns, and preferred-side denture tooth wear, affecting older adults using complete removable dentures. Results: Mandibular movement characteristics—particularly velocity, duration, and cycle frequency—were found to significantly influence denture tooth wear, often resulting in reduced bite force and masticatory efficiency. Contemporary denture materials demonstrated improved wear resistance, aiding in the regulation of chewing frequency and velocity. These factors are increasingly important as age-related changes impact the stomatognathic system. Notably, wear facets were most prominent on the maxillary first molars, regardless of the occlusal scheme. Conclusions: This review provided a comprehensive overview of existing research, analyzed current evidence, and offered insights into the role of masticatory function and wear characteristics in older complete denture wearers. Full article

Objectives: This study aimed to establish reference values for bite force in individuals with various prosthetic restorations and to examine the relationship between prosthetic treatment groups (PTGs) and bite force as an indicator of masticatory muscle function. Materials and Methods: In a cross-sectional study from November 2021 to March 2023, 198 participants aged 18 to 95 years were recruited from multiple dental and geriatric centers. The participants were assigned to seven PTGs based on their dental and prosthetic statuses. Bite force was measured using the Occlusal Force Meter GM10, with three recordings on each side of the jaw, and analyzed using ANOVA. Results: The bite force decreased with fewer teeth and the transition from fixed to removable dentures. Fully dentate participants exhibited the highest bite forces, differing significantly from the other groups (p < 0.001). For the fully dentate individuals (547 ± 240 N), the bite force decreased progressively with the extent of prosthetic restoration, reaching 55 ± 45 N in edentulous individuals with complete dentures in both jaws. However, edentulous participants with two interforaminal implants demonstrated higher bite forces than those with partial dentures. Conclusions: Bite force is significantly impacted by prosthetic restoration type. Fully dentate individuals have the highest bite forces, while edentulous patients with implant-supported dentures also show considerable bite forces, similar to those with partial dentures. Full article

Background: Mucostatic impressions have been always indicated in thin, sharp, or flabby ridges, and have been addressed for their beneficial effect on long-term residual ridge stability. Nonetheless, a purely mucostatic impression was not possible until intraoral scans became available. This provides an option for digital removable denture which is biologically sensible but might reduce retention in comparison with a mucocompressive impression with border molding. On the other hand, pressure applied to the mucosa may have harmful effects on the long-term residual ridge stability, causing higher resorption and ultimately reduced denture retention. Hence, the possibility to merge mucostatics and mucocompressive philosophies would be a clinically and biologically sensible option for oral rehabilitation in aging populations where patients will potentially wear dentures for longer periods. This possibility is demonstrated in this technical report with a cast-free digital workflow. Technique: Baseplates for occlusion rims, closely adapted to the mucosa, were designed on intraoral scans of edentulous arches and, once 3D-printed, used to register maxillomandibular relations and information for tooth arrangement, as well as to perform border molding. Occlusion rims were then scanned and, within the 3Shape Dental System 2024 software program, the intaglio surfaces of their baseplates were segmented and inverted to obtain the digital master casts which incorporated the precise reproduction of the molded borders. Then, denture design was performed and manufactured; no limitations regarding manufacturing options are applicable to the presented technique. Conclusions: The potential benefits (i.e., improved retention in the initial period after denture delivery and the preservation of tissues) of the presented digital cast-free workflow, based on merging mucostatic and mucocompressive philosophies to obtain dentures with a mucostatic intaglio surface and functional borders, are sensible clinical outcomes which recommend the clinical application of the technique, although further validation, especially in the long term, is required. Full article

Biomechanical bite analysis is essential for understanding occlusal forces and their distribution, especially in the design and validation of dental prostheses. Although the finite element method (FEM) has been widely used to evaluate these forces, the existing models often lack accuracy due to simplified geometries and limited material properties. Methods: A detailed finite element model was developed using Abaqus Standard 2023 software (Dassault Systemes, Vélizy-Villacoublay, France), incorporating scanned 3D geometries of mandibular and maxillary bones. The model included cortical and cancellous bones (Young’s modulus: 5.5 GPa and 13.7 GPa, respectively) and was adjusted to simulate bite forces of 220.7 N based on experimental data. Occlusal forces were evaluated using flexible connectors that replicate molar-to-molar interactions, and the stress state was analyzed in the maxillary and mandibular bones. Results: The FEM model consisted of 1.68 million elements, with mesh sizes of 1–1.5 mm in critical areas. Bite forces on the molars were consistent with clinical trials: first molar (59.3 N), second molar (34.4 N), and third molar (16.7 N). The results showed that the maximum principal stresses in the maxillary bones did not exceed ±5 MPa, validating the robustness of the model for biomechanical predictions. Conclusion: The developed model provides an accurate and validated framework for analyzing the distribution of occlusal forces in intact dentures. This approach allows the evaluation of complex prosthetic configurations and their biomechanical impact, optimizing future designs to reduce clinical complications and improve long-term outcomes. The integration of high-resolution FEM models with clinical data establishes a solid foundation for the development of predictive tools in restorative dentistry. Full article

Background and Objectives: Functional rehabilitation in patients with hemimandibulectomy remains a challenge no matter what method of reconstruction is chosen by physicians. In this paper, we aim to evaluate the feasibility of an acceptable occlusal restoration in patients who have undergone hemimanidublectomy without the reestablishment of mandibular continuity. Materials and Methods: Data were collected retrospectively on 10 patients with varying degrees of mandible resection. The greatest challenge in the restoration of an acceptable occlusion form is the natural latero-deviation that occurs in patients whose mandibular continuity was not restored. This causes an unbalanced and uncoordinated occlusal plane. Based on our research, this deviation is highly dependent on three main factors: the presence of teeth (which allow for a proprioceptive stimulus that counteracts the deviation), the extension of the defect and the presence or lack of the coronoid process. Results: Based on the presence of dental elements or lack thereof, patients were either rehabilitated with implant-supported dentures or removable partial dentures. Although the gold standard of care for these patients remains the restoration of mandible continuity through use of bone grafts, an acceptable rehabilitation of occlusion and therefore function may be acquired in non-grafted patients. Conclusions: Both physicians and patients must manage their expectations carefully and be eager to find a compromise to provide the best possible solution given the challenges of the premises. Full article

The purpose of this study was to determine the effect of fiber reinforcement materials on the magnitude of stresses in a critical part of the maxillary denture base under thermal and occlusal load. Thermal stress analyses of the models were carried out using the finite element method. The models consisted of bone, soft tissue, interface gap, and maxillary dentures with and without reinforcements. A concentrated occlusal load of 230 N was applied bilaterally on the molar teeth. A 36 °C reference and 0 °C, 36 °C, and 70 °C variable ambient temperatures were applied to the models. CrCo, unidirectional and woven carbon/epoxy, unidirectional and woven glass/epoxy, and unidirectional and woven Kevlar/epoxy were used as reinforcing materials in the maxillary denture base made of PMMA (polymethyl methacrylate). Stress distributions on the maxillary denture’s midline and lateral line direction were evaluated. Maximum stresses in the incisal notch and the labial frenal notch of the maxillary denture were determined. Failure analysis of reinforcement materials used in maxillary dentures was carried out using the Tsai-Wu index criterion. The results obtained show that the thermal properties of reinforcement materials should be considered as an important criterion in their selection. Full article

Background and Objectives: Oral rehabilitation seeks to enhance mastication, a vital component of oral function that is compromised by tooth loss. This study aimed to assess the degree of improvement of masticatory performance in partially edentulous patients rehabilitated with removable partial dentures (RPD) or fixed partial dental prosthesis (FPDP). Changes in the occlusal contact area (OCA) and satisfaction with their chewing ability during the adaptation period were also evaluated. Materials and Methods: in total, 34 partially edentulous participants (median age 65.3 years; 56% women) who received an RPD or FPDP were assessed using masticatory performance assay, OCA calculation, and a visual analog scale (VAS). Results: Masticatory performance improved by 20% (range from 17% to 25%, p < 0.05) depending on the edentulism and the rehabilitation types. The OCA improved by 4.7 mm² (p < 0.05) and satisfaction with the masticatory function improved by 9% (p < 0.05) 3 months after prosthesis insertion. Conclusions: Conventional prostheses benefited partially edentulous individuals, improving masticatory performance by 20%. Treatment also increased the OCA in all types of partial edentulism, except in Kennedy class I patients rehabilitated with RPD. Patients’ satisfaction with their chewing ability only increased in Kennedy class III patients rehabilitated with RPD. Full article

Additive manufacturing resins used in dental prosthetics may retain uncured monomers post-polymerization, posing potential long-term patient exposure risks. Understanding the biological safety of these materials is crucial, particularly for 3D-printed acrylic-based prosthodontic devices such as occlusal nightguards, complete and partial dentures, and temporary fixed prostheses. This paper reviews the literature evaluating the cytotoxicity of such materials. Following the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA) guidelines, we conducted a scoping review using the MESH keywords related to population (P), intervention (I), comparison (C), and outcome (O) across databases, including OVID Medline, EMBASE, and SCOPUS. Our search, limited to peer-reviewed English language articles from 2015 to 2023, resulted in 22 papers. These studies, utilizing digital light processing (DLP) or stereolithography (SLA) printing methods, varied in examining different 3D-printed materials, as well as washing and post-curing protocols. The primary experimental cells used were human gingival fibroblasts (HGF) and mouse fibroblasts (L929). There are no statistical differences in biocompatibility regarding different commercially available resins, washing solutions, or methods. Improvements in cell viability were related to an increase in washing time, as well as post-curing time. After the polishing procedure, 3D resin-based printed occlusal devices perform similarly to milled and conventionally processed ones. Our findings underline the importance of appropriate washing and post-curing protocols in minimizing the cytotoxic risks associated with these 3D-printed resin-based devices. Full article

The literature presents insufficient data evaluating the displacement and micromotion effects resulting from the combined use of tooth-implant connections in fixed partial dentures. Analyzing the biomechanical behavior of tooth-implant fixed partial denture (FPD) prothesis is vital for achieving an optimum design and successful clinical implementation. The objective of this study was to determine the relative significance of connector design on the displacement and micromotion of tooth-implant-supported fixed dental prostheses under occlusal vertical loading. A unilateral Kennedy class I mandibular model was created using a 3D reconstruction from CT scan data. Eight simulated designs of tooth-implant fixed partial dentures (FPDs) were split into two groups: Group A with rigid connectors and Group B with non-rigid connectors. The models were subjected to a uniform vertical load of 100 N. Displacement, strain, and stress were computed using finite element analysis. The materials were defined as isotropic, homogeneous, and exhibiting linear elastic properties. This study focused on assessing the maximum displacement in various components, including the bridge, mandible, dentin, cementum, periodontal ligament (PDL), and implant. Displacement values were predominantly higher in Group B (non-rigid) compared to Group A (rigid) in all measured components of the tooth-implant FPDs. Accordingly, a statistically significant difference was observed between the two groups at the FPD bridge (p value = 0.021 *), mandible (p value = 0.021 *), dentin (p value = 0.043 *), cementum (p value = 0.043 *), and PDL (p value = 0.043 *). Meanwhile, there was an insignificant increase in displacement values recorded in the distal implant (p value = 0.083). This study highlighted the importance of connector design in the overall stability and performance of the prosthesis. Notably, the 4.7 mm × 10 mm implant in Group B showed a displacement nearly 92 times higher than its rigid counterpart in Group A. Overall, the 5.7 mm × 10 mm combination of implant length and diameter showcased the best performance in both groups. The findings demonstrate that wider implants with a proportional length offer greater resistance to displacement forces. In addition, the use of rigid connection design provides superior biomechanical performance in tooth-implant fixed partial dentures and reduces the risk of micromotion with its associated complications such as ligament overstretching and implant overload, achieving predictable prognosis and enhancing the stability of the protheses. Full article

Objective: This randomized, single-blind controlled study aimed to investigate the QoL and satisfaction of patients wearing complete dentures with lingualized (LO) and bilaterally balanced occlusion (BBO). Participants were stratified based on their prior experience with complete dentures. Methods: The study involved 131 complete denture wearers who were categorized into four groups: G1—first-time prosthesis wearers treated with LO (n = 33); G2—first-time prosthesis wearers treated with BBO (n = 31); G3—participants with prior prosthesis experience treated with LO (n = 34); G4—participants with prior prosthesis experience treated with BBO (n = 33). After wearing the prosthesis for one month, all participants completed the Oral Health Impact Profile (OHIP-14) questionnaire. A statistical analysis was conducted using the χ² test, Kruskal–Wallis analysis and Mann–Whitney test, with significance determined at p < 0.05. Results: After dividing the respondents into two groups, a statistically significant difference was observed in the distribution of scores for three questions related to oral pain severity, anxiety, and difficulty relaxing. However, the distribution of scores for all other questions did not show a statistically significant difference between the groups studied (p < 0.05). The total OHIP-14 score was also not statistically different (z = 0.469; p = 0.639). However, when respondents were divided into four groups, the median score for first-time denture wearers was 3.9 points higher in respondents who received dentures with BBO compared to those with LO (p < 0.001). Furthermore, the median score for first-time denture wearers who received BBO was higher than for those in the second group who received BBO (p = 0.013). Conclusion: Patients wearing complete dentures for the first time demonstrated significantly higher satisfaction with the LO scheme compared to the BBO scheme. In contrast, satisfaction levels between occlusal schemes did not significantly differ among patients with prior denture-wearing experience. Novice denture wearers reported heightened sensations of oral discomfort, anxiety, and difficulty relaxing regardless of the occlusal scheme compared to experienced wearers, likely due to the unrealistic expectations that first-time wearers often have about complete dentures. Full article