Search Results (137)

Interim fixed dental prostheses (FDPs) must withstand functional loading, thermal fluctuation, and moisture, yet comparative fracture resistance of additively manufactured, CAD/CAM-milled, and conventionally polymerized provisional materials after artificial aging remains unclear. Ninety three-unit interim FDPs (n = 30 per material) were fabricated from an additively manufactured photopolymer resin, CAD/CAM-milled poly(methyl methacrylate) (PMMA), or a conventionally autopolymerized powder–liquid poly(ethyl methacrylate) (PEMA)-based resin, and divided into non-aged and aged subgroups (5000 thermal cycles, 5/55 °C; n = 15). Restorations were seated without cementation on rigid titanium dies and loaded at the pontic to fracture (4 mm spherical indenter, 0.5 mm/min). The material-fabrication workflow grouping showed the largest effect on maximum fracture load (p < 0.001, η²p = 0.923): CAD/CAM-milled PMMA (1131.95 ± 135.31 N) > PEMA-based resin (475.06 ± 171.96 N) > photopolymer resin (163.34 ± 36.79 N). A material × aging interaction (p = 0.009) indicated that thermocycling reduced fracture load only in milled PMMA. For time to maximum load, only the interaction was significant (p = 0.008), driven by the photopolymer group. Fracture location and pattern varied by group. Within the limitations of this in vitro study, differences in maximum fracture load were primarily associated with the investigated material-fabrication workflow combinations, whereas aging effects were material-dependent. Full article

Background: Severe tooth loss affects approximately 267 million people worldwide and has a significant impact on quality of life and general health. Various prosthetic treatment concepts exist for oral rehabilitation. The All-on-Four concept, first described by Maló in 2003, is considered a modern approach for timely and patient-friendly restoration of oral function and esthetics. Methods: A systematic literature search was conducted in the electronic databases MEDLINE/PubMed and EMBASE (Elsevier). Eligible studies were identified according to the framework, including investigations on the All-on-Four concept (PIO) and alternative implant-supported full-arch rehabilitation strategies (FDP4+, PCO). The methodological quality of the included studies was assessed using the Newcastle–Ottawa Scale. Results: Following the selection process, eleven PIO studies and nine PCO studies were included for qualitative analysis. Reported prosthesis survival rates were comparable between All-on-Four (85.0–100%) and concepts with more than four implants (88.2–100%) over up to 20 years. Implant survival ranged from 89.7–97.9% for All-on-Four and 98.9–99.0% for alternative concepts. Marginal bone loss after 5 years reached up to 1.9 mm for All-on-Four and 2.9 mm for alternative concepts. Metal–ceramic prostheses demonstrated lower fracture rates (7.27–18.2%) compared with metal–acrylic restorations (7.3–36.7%). Discussion: The available evidence suggests that the All-on-Four concept represents a predictable treatment option for edentulous patients, with implant and prosthetic survival rates comparable to FDP4+ concepts. Immediate loading protocols may improve patient satisfaction and reduce treatment time when adequate primary stability is achieved. However, biological and technical complications remain clinically relevant. Interpretation of the findings is limited by heterogeneous study designs and predominantly retrospective evidence. Conclusions: The All-on-Four concept provides a reliable rehabilitation option for patients with advanced ridge atrophy who decline regenerative procedures or removable prostheses. Current evidence indicates no significant differences in survival or complication rates compared to other implant-supported treatment concepts. Full article

The aim of this in vitro study is to evaluate the stress distribution of different definitive restorative materials designed with different connector dimensions using finite element analysis. Two adjacent prepared maxillary molars were designed digitally. Two-unit splinted fixed dental prostheses (FDPs) were designed with 4 different triangular connector dimensions (2 × 3, 3 × 3, 3 × 4, and 4 × 4 mm (width × length)). The tested materials are Gold Metal, Base Metal Alloy, Feldspathic Porcelain, Lithium Disilicate, Zirconia, and Zirconia-Reinforced Lithium Silicate. A total of 56 two-unit splinted crowns models were designed and evaluated using finite element analysis (FEA) in Autodesk Fusion 360. FEA demonstrated a non-linear relationship between connector size and performance, with the 3 × 4 mm design exhibiting optimal stress distribution and the highest safety factor. Among different materials, the base metal alloy showed the highest safety factor across all configurations, while zirconia and lithium disilicate performed comparably under static loading. The 3 × 4 mm connector demonstrated optimal performance across all tested materials. Base metal alloy exhibited the highest safety factor among all connector dimensions. Full article

Additive manufacturing is increasingly integrated into digital prosthodontic workflows for the fabrication of dental models; however, printing-related parameters may influence the dimensional accuracy of clinically relevant regions. This in vitro study evaluated the effect of support spacing on the region-specific dimensional accuracy of masked stereolithography (MSLA)-printed dental models. A standardized typodont model representing a three-unit posterior fixed dental prosthesis preparation in the FDI 24–26 region was digitized to obtain a reference STL dataset. Three support spacing configurations were evaluated: 3 mm, 5 mm, and 7 mm (n = 8 per group). All specimens were fabricated using an MSLA printer and a photopolymer model resin at a layer thickness of 50 μm. After post-processing, the printed models were rescanned and compared with the reference dataset using three-dimensional deviation analysis. Root mean square (RMS) deviations were calculated for global, marginal, intaglio, and adjacent regions. Significant differences were observed in the global (p < 0.001), marginal (p = 0.001), and intaglio (p = 0.010) regions, whereas adjacent regions were not significantly affected (p = 0.070). Increasing support spacing was associated with greater dimensional deviations in the global and intaglio regions. Overall, the 3-mm support spacing demonstrated the most consistent dimensional performance across the evaluated regions. These findings indicate that support spacing is an important design parameter influencing the dimensional predictability of MSLA-printed dental models and highlight the value of region-specific accuracy assessment for optimizing support design in digital prosthodontic workflows. Full article

Objectives: To systematically evaluate the influence of connector design and pontic span length on the mechanical performance of zirconia fixed dental prostheses (FDPs). Methods: A systematic review was conducted according to PRISMA 2020 guidelines (8). Electronic searches were performed in PubMed, Scopus, Web of Science, and Embase. In vitro and finite element analysis (FEA) studies evaluating zirconia FDPs were included. Results: A total of 11 studies were included. Across all studies, connector regions were consistently identified as the primary site of fracture initiation. Reduced connector dimensions significantly decreased fracture resistance and fatigue life, whereas increased cross-sectional area and optimized geometry improved stress distribution and mechanical performance. Longer pontic spans were associated with increased stress concentration and reduced structural stability. Conclusions: Connector design and pontic span length are critical determinants of the biomechanical behavior of zirconia FDPs. Clinical significance: Optimization of connector dimensions and geometry is essential to improve the longevity and reliability of zirconia FDPs. Full article

Background: Tooth-supported fixed dental prostheses (FDPs) remain relevant when implant therapy is limited, but their mechanical behavior depends on material selection, connector design, retainer design, prosthesis configuration, and abutment support. This systematic review assessed how these factors affect fracture behavior and stress transmission in tooth-supported FDPs. Materials and Methods: PubMed/MEDLINE, Scopus, Web of Science Core Collection, and Dentistry and Oral Sciences Source were searched for English-language studies published from 1 January 2016 to 15 May 2026. Eligible studies were in vitro mechanical, fatigue, fracture-resistance, or finite element analysis (FEA) studies of tooth-supported FDP designs. Clinical studies were screened during eligibility assessment, but no clinical study met the final inclusion criteria for primary synthesis. In vitro components were appraised with the Quality Assessment Tool for In Vitro Studies (QUIN), and FEA components were appraised with the Risk-of-bias Framework for Dental Finite Element Analysis (ROBFEAD). Findings were synthesized narratively by evidence type and biomechanical theme. Results: Twenty-nine studies were included: 11 in vitro-only studies, 14 FEA-only studies, and four combined experimental and computational studies. No eligible clinical study met the final inclusion criteria. Zirconia-based systems were the most frequent focus. Their behavior depended on connector dimensions, connector shape, framework design, span, retainer configuration, loading direction, abutment selection, periodontal support, and bone support. Larger connector dimensions or greater connector height often improved fracture resistance or reduced modeled stress in zirconia models, but connector area alone did not explain performance across all materials and designs. Conservative FDPs were sensitive to retainer geometry, adhesive-interface behavior, connector design, and abutment support. Conclusions: Current evidence is limited to laboratory and computational studies. Tooth-supported FDP biomechanics should be interpreted as a material, design, and support system, not as a material effect alone. Full article

Objective: The purpose of these two clinical cases reports was to present the variations in the surgical and prosthetic procedures related to an implant-supported fixed dental prosthesis (FDP) in the edentulous maxilla, following a fully guided implantation protocol and immediate loading. Case presentation: Two patients, one with terminal dentition and one with a completely edentulous maxilla, expressed the desire for immediate rehabilitation with an FDP and avoidance of multiple and complex surgical procedures. The clinical protocol for both cases included meticulous presurgical planning combining radiographic examination, diagnostic wax-up (conventional or digital), prosthetically driven digital planning of implant placement, fabrication of a surgical guide for fully guided implant installation, and delivery of a screw-retained fixed restoration. There was no report of any implant failure; the FDPs could be delivered as planned, and both patients expressed their satisfaction with the functional and esthetic outcomes. The clinical situation was stable at the recall. Full article

Background/Objectives: Halitosis in geriatric patients is multifactorial, but the joint contribution of prosthetic rehabilitation type and polypharmacy after routine dental procedures has rarely been quantified. We investigated how prosthesis type, polypharmacy, and salivary function were associated with volatile sulfur compound (VSC) burden and self-perceived halitosis in elderly dental patients. Methods: This cross-sectional study enrolled 88 patients aged ≥65 years, four weeks after completing routine dental procedures. Participants were stratified into three groups: complete denture wearers (n = 30), partial removable denture wearers (n = 28), and fixed prostheses/implants (n = 30). We measured unstimulated salivary flow rate (uSFR), tongue coating index (TCI), denture biofilm index, total VSCs (Halimeter^®), organoleptic score (0–5), and self-perceived halitosis. Polypharmacy, comorbidities, and the Geriatric Oral Health Assessment Index (GOHAI) were recorded. Analyses included one- and two-way ANOVA, Spearman correlations, theory-informed multivariable linear and logistic regression, exploratory mediation analysis, and ROC curves. Results: Forty-two participants (47.7%) reported halitosis. Mean VSC differed across groups (complete dentures 278.2 ± 38.6 ppb; partial 211.2 ± 46.3 ppb; fixed 164.4 ± 43.9 ppb; ANOVA p < 0.001). uSFR correlated inversely with VSC (ρ = −0.61, p < 0.001) and TCI correlated positively (ρ = 0.56, p < 0.001). A significant prosthesis × polypharmacy interaction was observed (F = 3.74, p = 0.029, η²_p = 0.082): polypharmacy was associated with higher VSC most clearly among partial and fixed prostheses wearers, whereas complete denture wearers showed high VSC levels regardless of polypharmacy status. Exploratory mediation findings were consistent with partial indirect association, with 45.9% of the polypharmacy–VSC association statistically explained by reduced uSFR; however, the cross-sectional design precludes causal or temporal interpretation. The full multivariable model showed apparent discrimination for self-perceived halitosis (AUC = 0.92), while the simplified four-item chairside composite model showed AUC = 0.89; neither estimate was optimism-corrected or externally validated. Conclusions: In elderly post-procedure patients, complete denture wearing, polypharmacy, and salivary hypofunction were independently and jointly associated with higher halitosis burden. Reduced salivary flow was consistent with a partial indirect statistical pathway in the polypharmacy–VSC association, supporting hydration counseling and meticulous prosthesis hygiene as low-cost geriatric interventions. Sensitivity analyses excluding implant-supported restorations, participants with MMSE scores of 24–26, and expanded mediation models including TCI and biofilm/plaque did not materially change the main inference. Full article

Background and Objectives: Halitosis is a prevalent oral concern that meaningfully affects oral health-related quality of life (OHRQoL), yet how active dental treatment is associated with short-term changes in the objective–subjective halitosis–QoL nexus remains poorly quantified. Interpretation is complicated by the multifactorial nature of malodor and by baseline differences between patients selected for different dental procedures. We compared changes in volatile sulfur compound (VSC) emissions, organoleptic ratings, tongue-coating burden, and OHIP-14 across three contrasting treatment modalities and explored whether VSC change statistically accounted for OHRQoL change. Methods: In a non-randomized prospective comparative study, 119 adults (18–67 y) commencing one of three procedures were assessed at baseline and at 8 weeks: scaling and root planing (Group A, n = 42), fixed prosthodontic rehabilitation (Group B, n = 38), or fixed orthodontic appliance bonding (Group C, n = 39). Outcomes included Halimeter^® VSC (ppb), Rosenberg organoleptic score (0–5), Winkel tongue-coating index (TCI), self-perceived halitosis, and OHIP-14 total and seven-domain scores. Mixed-design ANOVA, ANCOVA, prespecified multivariable regression, mediation (5000 bootstrap resamples), receiver operating characteristic analysis, and four-class latent class analysis were performed. A sensitivity-analysis framework including expanded covariate adjustment, propensity-score overlap weighting, and baseline-severity strata was also applied to address residual baseline imbalance. Secondary mediation, ROC, and latent-class analyses were considered exploratory. Results: At 8 weeks, VSCs fell by 116.4 ± 38.7 ppb in Group A and 35.4 ± 29.1 ppb in Group B but rose by 34.3 ± 28.6 ppb in Group C (p < 0.001). OHIP-14 improved by 10.3 and 4.9 points in A and B and worsened by 3.7 in C (p < 0.001). ΔVSC correlated with ΔOHIP-14 (ρ = 0.51, p < 0.001) and most strongly with the psychological discomfort domain (ρ = 0.58). VSC change mediated 35.1% of the periodontal-versus-orthodontic association on QoL (indirect β = −4.7; 95% CI −6.3 to −3.1). Because VSC and OHIP-14 changes were measured over the same interval, mediation was interpreted cautiously. A ΔVSC threshold of −63 ppb predicted clinically meaningful OHIP-14 improvement (AUC = 0.81). Latent class analysis identified four distinct responder phenotypes. The cutoff and responder classes were internally derived and require external validation. Sensitivity analyses preserved the direction of the primary contrasts, but residual confounding remains possible. Conclusions: Treatment modality was associated with the direction and magnitude of halitosis and QoL change, with orthodontic patients constituting a vulnerable subgroup. Targeted oral-hygiene reinforcement during fixed-appliance therapy is warranted. Full article

Tooth-supported fixed partial dentures (FPDs) exhibit complex biomechanical behaviour because occlusal loads are transferred through the periodontal ligament (PDL) and heterogeneous mandibular bone. This pilot study aimed to develop a patient-specific NURBS-based finite element analysis (FEA) workflow for anatomically realistic mandibular reconstruction and to evaluate the biomechanical effect of geometric simplification in tooth-supported FPD simulations. Cone beam computed tomography data from a single subject were segmented and reconstructed into a layered three-dimensional model of the mandible and dentition, including cortical bone, cancellous bone, teeth, and PDL. A high-fidelity reference model (V0) and four simplified variants (V1–V4) were analysed under static 500 N loads applied at 0° and 30°. The reference model yielded a maximum von Mises stress of 507 MPa and a peak displacement of 0.74 mm, with stress concentrations consistently localised at the retainer–pontic connector region. Inclusion of the PDL markedly affected the mechanical response, doubling denture displacement in simplified comparative models. Among the simplified configurations, V4, which preserved cortical morphology and PDL representation while omitting detailed trabecular architecture, showed the closest agreement with the reference model, with mean deviations of 6.1% and 5.8% under the two loading conditions, respectively. These findings suggest that patient-specific NURBS–FEA modelling provides a robust framework for biomechanical assessment of tooth-supported FPDs, while controlled simplification may improve computational efficiency without substantially compromising accuracy under static loading conditions. Full article

Background/Objectives: Immediate-loading interim implant-supported complete-arch fixed dental prostheses (ISCFDPs) are widely used for immediate loading in edentulous patients. Although traditional denture conversion techniques are well established, newer systems aim to improve efficiency and prosthesis integrity. This clinical report aims to describe and compare four chairside conversion techniques for immediate-loading interim ISCFDPs. Methods: Four clinical cases were treated using different conversion techniques, including conventional denture conversion, guided conversion with static computer-assisted implant surgery (s-CAIS), and two closed-mouth pickup systems (SMART Denture Conversion and EasyPro). Clinical workflows, procedural characteristics, and prosthetic considerations were evaluated. Results: All techniques enabled the successful fabrication of immediate-loaded interim ISCFDPs. Conventional conversion was flexible and cost-effective but technique-sensitive and associated with increased risk of prosthesis weakening. Guided conversion improved structural integrity and reduced intraoral adjustment but required precise planning and higher costs. Closed-mouth systems preserved occlusion, minimized denture modification, and reduced chairside time, though they relied on proprietary components and had limited clinical evidence. Conclusions: Each conversion technique presents distinct advantages and limitations. Selection should be based on clinical conditions, available resources, and clinician experience. Further studies are needed to validate the long-term outcomes of emerging conversion systems. Full article

The aim of this in vitro study is to evaluate the stress distribution of different provisional materials designed with different connector dimensions using finite element analysis. Two adjacent prepped maxillary molars were designed digitally. Two-unit connected fixed dental prostheses (FDPs) were designed with four different connector dimensions (2 × 3, 3 × 3, 3 × 4, 4 × 4 mm (width × length)). The tested materials included polymethyl methacrylate (PMMA), bis-acrylate composite, and polyetheretherketone (PEEK). A total of 24 two-unit FDPs were tested using FEA in Autodesk Fusion 360. The study demonstrated a non-linear relationship between connector size and performance, with the 3 × 4 mm design exhibiting optimal stress distribution and the highest safety factors. Among materials, PMMA showed the greatest resistance to deformation, while PEEK provided the highest safety margins against yielding in optimal connectors. The 2 × 3 mm bis-acrylate composite configuration presented a critical failure risk, with stresses exceeding the material yield strength by 25-fold. Force angulation (0° vs. 10°) showed minimal effect on overall displacement patterns. Within the study limitations, the 3 × 4 mm connector demonstrated optimal performance across all materials. PEEK provided the highest safety factor in well-designed connectors, while bis-acrylate composite posed the greatest failure risk, particularly in smaller dimensions. Full article

Background/Objectives: Connective tissue grafting (CTG) has been proposed to enhance ridge contour at pontic sites; however, its long-term volumetric stability remains unclear. This systematic review evaluated three-dimensional (3D) volumetric and linear soft-tissue changes over time following CTG at pontic sites. Methods: A systematic search was conducted in PubMed/MEDLINE, Embase, Cochrane Library, LILACS, Scopus, Web of Science, and Google Scholar. Clinical studies assessing linear and/or volumetric soft-tissue outcomes at pontic sites treated with CTG, with a minimum follow-up of six months, were included. Study selection, data extraction, and risk-of-bias assessment were performed independently by two reviewers using RoB 2 and ROBINS-I tools. Results were synthesized descriptively. Results: Seven studies (two randomized and five non-randomized) were included. CTG was associated with consistent early improvements in ridge contour and soft-tissue volume. Over time, minor dimensional reductions were observed, and differences between grafted and nongrafted sites tended to decrease after the initial remodeling phase. Long-term follow-up (up to 15 years) suggested overall stability of both volumetric and linear outcomes. However, the evidence is limited by a small number of studies, methodological heterogeneity, and predominance of non-randomized designs. Conclusions: CTG provides early soft-tissue augmentation at pontic sites, but its long-term advantage over non-grafted healing appears limited. Given the very low certainty of evidence, these findings of such studies should be interpreted with caution in clinical decision-making. Full article

Objectives: Endodontic complications are among the most frequently reported biological complications in tooth-supported fixed dental prostheses (FDPs). The aim of this study was to evaluate the prevalence of periapical complications in FDPs placed on vital and non-vital abutments and to identify risk factors for these lesions. Methods: This retrospective clinical trial was conducted on participants who had attended routine follow-up visits at the dental hospital at Qassim University, Saudi Arabia. Participants were examined clinically and radiographically for the presence of periapical lesions. Information was recorded on the design, material, location of the prostheses, and oral hygiene. The survival and lesion-free survival rates were determined using the Kaplan–Meier method. Life-table analysis was performed to assess the mean time to event. Univariate Cox proportional hazards regression analysis was used to assess potential risk factors for the development of periapical lesions (α = 0.05). Results: A total of 495 FDPs were placed in 302 participants, with a mean age of 45.7 ± 13.4 years and a mean follow-up period of 7.5 ± 6.5 years. Lesions were detected in 32.3% of FDPs during follow-up. There were no significant differences in the prevalence of lesions in vital compared with non-vital abutments or between males and females (p > 0.05). Poor oral hygiene was the most significant risk factor for the development of periapical lesions (p < 0.05). Univariate Cox regression analysis showed that anterior–posterior FDPs had a higher risk of lesions (p = 0.035). No significant associations were found between lesions and the material used or the design of the abutment (p > 0.05). Conclusions: Periapical complications in FDPs are mainly influenced by oral hygiene and the location of the FDPs, whereas abutment vitality and material type appear to have limited impact. Full article

Aim: Fixed dental prostheses (FDPs) are increasingly fabricated from high-strength ceramic materials; however, their fracture behavior under flexurally dominated loading remains incompletely understood. This in vitro study aimed to compare the mechanical performance and fracture mechanisms of four FDP material systems under standardized bending conditions. Materials and Methods: Three-unit CAD/CAM-fabricated FDPs were produced from metal-ceramic (P1), zirconia-ceramic (P2), monolithic zirconia (P3), and monolithic lithium disilicate (P4) materials (n = 9 per group). Specimens were subjected to three-point bending until failure. Crack initiation load, maximum load, displacement, and stiffness were recorded, and fracture behavior was analyzed using stereomicroscopy, micro-computed tomography (μCT), and scanning electron microscopy (SEM). Results: Metal-ceramic FDPs (P1) exhibited the highest crack initiation load (0.89 kN) and maximum load (1.91 kN), with failure predominantly occurring through ceramic veneer delamination without complete framework fracture. Monolithic zirconia FDPs (P3) demonstrated the most brittle failure behavior, characterized by abrupt fracture and unstable crack propagation immediately after crack initiation. Zirconia-ceramic (P2) and lithium disilicate (P4) FDPs showed intermediate mechanical performance, with lithium disilicate exhibiting greater resistance to catastrophic failure (F_max = 0.94 kN) compared with zirconia–ceramic FDPs. Conclusions: These findings refine current assumptions regarding the mechanical reliability of monolithic zirconia FDPs under flexural loading and highlight the importance of fracture behavior, rather than peak strength alone, in material selection. Lithium disilicate and metal-ceramic systems exhibited more favorable damage-tolerant responses under static flexural loading. These findings should be interpreted within the limitations of this in vitro model and should not be directly extrapolated to long-term clinical performance. Full article