Clinical performance of zirconia-based tooth-supported fixed dental prostheses: a systematic review and meta-analysis.

OBJECTIVES: This study aimed to investigate the clinical performance of zirconia-based fixed dental prostheses (FDPs) in comparison to metal-ceramic (MC) FDPs. METHODS: A comprehensive search on MEDLINE (PubMed), Web of Science (Core Collection), Scopus up to June 2024 was conducted. Studies that compared the success, survival and complication rates between zirconia based FDPs and MC FDPs were eligible for inclusion. RESULTS: Thirty-one articles were identified, of which 22 were included for systematic review and 7 RCTs were included for meta-analysis. 10, 9 and 3 studies were classified to mean follow-up ≤ 5 years, 5 years < mean Follow-up ≤ 10 years, mean Follow-up >10 years, respectively. In the pooled analysis, 180 bilaminar zirconia (ZC) FDPs and 206 MC FDPs were included. ZC FDPs were significantly associated with more failures (RR=3.64, p=0.009) and more Ceramic Chipping (RR=2.92, p<0.0001) when compared to MC FDPs. Higher risks of Framework Fracture (RR=4.57, p=0.18), Loss of Retention (RR=4.79, p=0.17), Secondary Caries (RR=1.25, p=0.68), Endodontic complications (RR=1.30, p=0.74) and Marginal Integrity (RR=1.07, p=0.88) were also found in ZC FDPs when compared to those of MC FDPs, but with no statistical difference. CONCLUSION: The current evidence continues to support the preference for traditional MC FDPs over ZC FDPs. Studies indicate that ZC FDPs have higher failure rates and more complications compared to MC FDPs, with ceramic chipping being a significant concern. There is lack of long term (>10 years follow-up) evidence of the clinical performance of ZC FDPs and monolithic zirconia FDPs. CLINICAL SIGNIFICANCE: The study suggests that despite the growing popularity of zirconia, evidence shows MC FDPs may still be considered preferable to ZC FDPs.

Assessment of oral hygiene and quality of life in rehabilitated patients with fixed parcial dentures.

OBJECTIVE: Analyze the influence of oral hygiene guidance for the maintenance of fixed partial dentures (FPD) and the influence of this treatment on the quality of life (QL) of rehabilitated patients. MATERIAL AND METHODS: The Simplified Oral Hygiene Index (OHI-S) and Bleeding on Probing Index (BOP) methods was employed to evaluate oral hygiene (OH), and the OHIP-14 questionnaire to assessment QL. The sample consisted of 33 patients (26 females and 7 males, mean age 51.53 years) in treatment with FPD. The OH and QL assessments were conducted in temporary FPD placing session and 30 days after definitive cementation. R e s u l t s: OHI-S and BOP showed increasing results (p <0.05) comparing initial and final assessments. There was a negative correlation between OHI-S and BOP, in both periods of analysis. The OHIP-14 showed a significant result according to the Likert scale scores, with an impact reduction from 9.33 to 0.57. CONCLUSIONS: It was concluded that FPD rehabilitations need of properly oral hygiene guidance, that could be influence on oral health status. In addition, the FPD rehabilitation improved the QL of the patients.

Mechanical Properties of Additive-Manufactured Composite-Based Resins for Permanent Indirect Restorations: A Scoping Review.

The introduction of 3D printing technology in dentistry has opened new treatment options. The ongoing development of different materials for these printing purposes has recently enabled the production of definitive indirect restorations via 3D printing. To identify relevant data, a systematic search was conducted in three databases, namely PubMed, Scopus, and Web of Science. Additionally, a manual search using individual search terms was performed. Only English, peer-reviewed articles that encompassed in vitro or in vivo research on the mechanical properties of 3D-printed composite materials were included, provided they met the predefined inclusion and exclusion criteria. After screening 1142 research articles, 14 primary studies were selected. The included studies mainly utilized digital light processing (DLP) technology, less commonly stereolithography (SLA), and once PolyJet printing technology. The material properties of various composite resins, such as VarseoSmile Crown Plus (VSC) and Crowntec (CT), were studied, including Vickers hardness, flexural strength, elastic modulus, compressive strength, tensile strength, fracture resistance, and wear. The studies aimed to compare the behavior of the tested additive composites to each other, conventional composites, and subtractive-manufactured materials. This scoping review examined the mechanical properties of composites used for 3D printing of definitive restorations. The aim was to provide a comprehensive overview of the current knowledge on this topic and identify any gaps for future research. The findings suggest that 3D-printed composites are not yet the first option for indirect restorations, due to their insufficient mechanical properties. Due to limited evidence, more research is needed in this area. Specifically, there is a need for clinical trials and long-term in vivo research.

Impact of Fixed Partial Dentures on Oral Microbial Flora and Gingival Health: An In Vitro Assessment of Salivary Microbial Profiles.

Introduction The oral cavity hosts diverse microorganisms affected by factors like pH, temperature, and oxygen levels, influencing disease potential. Dentists manage oral diseases and improve aesthetics using durable restorations. Understanding periodontal response to crowns and fixed partial dentures (FPDs) is essential for effective treatment. This study aims to assess the impact of FPDs on periodontal health by comparing microbial colonies in individuals with and without FPDs. The hypothesis is that there will be no difference in microbial flora and gingival health between the two groups. Materials and methods This in vitro study utilized 40 salivary samples divided into two groups: 20 from patients with FPDs/crowns (Group 1) and 20 from patients without (Group 2). Unstimulated saliva was collected, diluted, and cultured on nutrient agar and Sabouraud Dextrose Agar to quantify anaerobic bacteria and Candida colonies. Colony counts were scored from 0 to IV based on colony-forming unit (CFU), and microscopic examination identified the types of microbes present. Data were analyzed using an unpaired t-test with IBM SPSS Statistics for Windows, Version 26 (Released 2019; IBM Corp., Armonk, New York, United States), with significance set at p < 0.05. Results The independent t-test analysis showed significantly higher mean CFUs of anaerobic microbes in Group 1 (experimental) compared to Group 2 (control) (p = 0.000). However, mean CFUs of Candida did not significantly differ between groups (p = 0.194). Microscopic examination identified Enterococcus faecalis, Pseudomonas aeruginosa, Candida albicans, Staphylococcus aureus, and Streptococcus mutans in the experimental group, whereas the control group contained only Staphylococcus aureus and Streptococcus mutans. Conclusion Individuals with FPDs exhibit higher concentrations of anaerobic microbes and specific bacteria, suggesting an increased risk of gingival inflammation and emphasizing the importance of maintaining good oral hygiene.

Enhancing Fixed Partial Denture Pontic Fabrication: An In Vitro Comparative Study of the Digital and Manual Techniques.

Background Advancements in computer-aided design (CAD) and computer-aided manufacturing (CAM) technology have significantly improved the accuracy and consistency of producing fixed partial dentures (FPDs) compared to traditional manual methods. However, the fully digital transfer of mock-up morphology to final FPDs is not yet fully explored. Proper pontic design, which avoids direct gingival contact, is essential for maintaining oral hygiene and preventing tissue irritation. Aim and objectives This study aims to compare the effectiveness of digital versus manual methods in FPD pontic fabrication, focusing on the trueness of digitally fabricated FPD patterns. Key objectives include assessing thickness, vertical gaps, and anatomical accuracy to determine the advantages of CAD-CAM technologies over traditional techniques. Materials and methods In this in vitro study, a total of 45 FPD pontics were fabricated and divided into three groups (15 each): digitally fabricated (using CAD software and CAM systems), manually fabricated (using traditional wax-up techniques), and a control group (typodont teeth). Tooth preparation was performed on a typodont, and impressions were taken to create casts. One cast was scanned and digitally designed, while the other was used for manual fabrication. Outcome assessments included vertical gap measurement using a stereo microscope, thickness evaluation with a digital caliper, and anatomical similarity assessment by independent evaluators. Statistical analysis involved one-way analysis of variance (ANOVA), post hoc Tukey's analysis, and unpaired t-tests using SPSS software version 26.0 (IBM Inc., Armonk, New York). Statistical significance was set at 0.05. Results The digital group exhibited lower mean thickness at the incisal (1.92±0.130 mm vs. 2.46±0.219 mm for manual, p=0.000), middle (7.00±0.223 mm vs. 8.88±0.983 mm for manual, p=0.001), and cervical sites (9.06±0.134 mm vs. 10.08±0.454 mm for manual, p=0.000). No significant differences were found between the digital and control groups. No significant differences were observed between digital, manual, and control groups at any site (p=0.688 to 0.997). The digital group demonstrated superior accuracy and consistency compared to the control group (mean value of 1.00±0.00 vs. 2.93±0.798, p=0.000). Conclusion CAD-CAM technology greatly improves the precision and consistency of FPD pontic fabrication compared to traditional manual techniques. Digital methods produce thinner pontics with superior anatomical accuracy, although vertical gap measurements are similar across methods. These findings emphasize the benefits of CAD-CAM in enhancing prosthetic outcomes and suggest potential improvements in clinical practices for prosthodontic rehabilitation.

Classification system for maxillary fixed dental prostheses.

PURPOSE: To present an addendum to existing fixed dental prostheses (FDPs) classification system for maxillary prostheses. The new classification identifies the relationships between FP-1 (fixed prostheses) designs and newly developed clinical interdental gingival contours. MATERIALS AND METHODS: Clinical and laboratory descriptions of the various types of full-arch fixed prostheses are described with photographic illustrations. Benefits and limitations of the various prosthetic designs are explained. Surgical differences in the amount of alveolectomy are illustrated. One clinical case is demonstrated. RESULTS: A new classification system for maxillary implant fixed complete dentures is presented. The new system will serve as an improved communication aid for clinicians, patients, and laboratory technicians. Treatment of patients with edentulous maxillae and/or terminal dentitions and implant fixed complete dentures include several options relative to design and materials. Restorative space can have a major impact on prosthesis design and longevity. Early on in dental implant therapy, prostheses were generally made with cast metal frameworks, denture bases and denture teeth. Prosthetic complications were widely reported. With increased clinical experience and improved materials, computer-aided design and computer-aided manufacturing (CAD-CAM) protocols were developed that allowed stronger prostheses to be constructed in reduced or small restorative volumes. FP-1 ceramic implant-supported fixed prostheses (CISFPs) are designed to replace only the dental hard tissues and to promote preservation and rehabilitation of gingival soft tissues. The physical properties and minimum thickness requirements in full arch prostheses are influenced by several factors including distances between implants and rigid connector sizes. CONCLUSION: FP-1 CISFPs may be the closest prostheses the profession can offer edentulous patients that mimic the look, feel, and function of missing dentitions. Aesthetic outcomes of FP-1 CISFPs are variable and depend on a multitude of factors. This article presented a classification system that builds on existing classification by identifying the level of papilla heights achieved with FP-1 CISFPs.

Factors influencing speech improvement following maxillary complete-arch implant-supported restorations: A retrospective study.

OBJECTIVE: This study explored factors affecting speech improvement in patients with an edentulous maxilla after the delivery of a complete-arch implant-supported fixed dental prosthesis (IFDP). MATERIALS AND METHODS: Patients who had received IFDP for edentulous maxilla were enrolled, and various potential speech improvement-related factors were considered, including patient demographics, anterior residual bone volume, preoperative facial features, preoperative acoustic parameters, and adaptation time. Acoustic analysis and perceptual ratings were used to assess three fricatives [s], [f], and [ɕ]. Correlation and regression analyses were conducted to assess the association between changes in fricatives and potential factors (α = .05). RESULTS: The study included 50 patients (18 females and 32 males, aged 50.62 ± 15.71 years, range 19-76). Significant correlations were found among the change in the center of gravity (ΔCoG) of [s] and anterior residual bone volume, zygomatic implants number and proportion (p < .05). These correlations were largely mirrored in the perceptual score (ΔPS) changes. After controlling for age, sex, preoperative acoustic parameters, and adaptation time, the ΔCoG and ΔPS of fricatives were mainly correlated with the anterior residual bone volume, preoperative acoustic parameters, and adaptation time. CONCLUSION: Speech improvements post-IFDP delivery are mainly related to preoperative speech characteristics, anterior residual bone volume, and adaptation time. The residual bone volume's impact on consonants varies with specific articulatory gestures. This study provides insights into forecasting speech outcomes following IFDP restoration and provides recommendations and methods for data collection in developing future prediction models.

Effect of the CAD/CAM Milling Protocol on the Fracture Behavior of Zirconia Monolithic Crowns.

Although advancements in CAD/CAM technology allow for more personalized treatments, it is not clear how modifications in the CAD/CAM milling process could affect the restoration surface conditions and their mechanical behavior. The objective of this study was to evaluate the effect of different CAD/CAM milling protocols on the topography and fracture behavior of zirconia monolithic crowns (3Y-PSZ) subjected to a chewing simulation. Monolithic 3Y-PSZ premolar crowns were milled using three protocols (n = 13) (slow (S), normal (N), and fast (F)). Crowns were cemented on a dentin analog abutment and subjected to mechanical aging (200 N, 2 Hz, 1,500,000 cycles, 37 °C water). Surviving crowns were subjected to compressive load test and analyzed using fractography. Fracture load data were analyzed with two-parameter Weibull analysis. The surface topography of the crowns was examined with a stereomicroscope and a 3D non-contact profiler. All crowns survived the chewing simulation. Crowns milled using the F protocol had the greatest characteristic fracture load, while crowns produced with the S protocol showed high Weibull modulus. Groups N and S had a more uniform surface and detailed occlusal anatomy than group F. The CAD/CAM milling protocol affected the topography and mechanical behavior of 3Y-PSZ monolithic crowns.

A proof of concept on implant-supported bilateral cantilever bridges: The T-Bridge approach.

The concept of bilateral cantilevers on a single central implant (T-design) for three-unit implant-supported fixed dental prostheses (ISFDPs) has not been explored nor tested. This technical hypothesis aimed to explore the feasibility of such an approach as a cost-effective alternative to conventional treatments. Careful considerations regarding implant diameter, length, ideal position, occlusal scheme, and bone remodeling are essential to ensure adequate support, stability, and prevention of complications. In this proof of concept, we present a preliminary case with this novel design to replace missing posterior teeth in a patient with narrow bone conditions. In addition, a series of planned investigations and preliminary results, including preclinical studies, are presented to illustrate our concept and its potential clinical implications. Clinically, after two-year follow-up, healthy and stable peri-implant tissues around the ISFDP exemplarily demonstrated excellent stability, functionality, and comfort, which is supported by acceptable fracture resistance data in vitro, suggesting indeed the practical potential and suitability. Thus, we claim that such a treatment modality has the at least theoretical potential to revolutionize implant dentistry by providing innovative and cost-effective treatment options for patients with partial ISFDPs in very specific cases. Of course, further research and evaluations are necessary to validate the clinical implications of this innovative hypothesis. Implementing the 3-on-1 T-bridge approach in partial ISFDPs could offer a promising alternative to traditional methods. If proven successful, this technique may lead to significant advancements in clinical practice, providing a less invasive cost-effective treatment option.

Validation of the pink esthetic score/white esthetic score at single tooth-supported prostheses in the esthetic zone: A randomized clinical trial.

OBJECTIVES: To validate the reproducibility and inter/intra-observer variability of the Pink Esthetic Score/White Esthetic Score (PES/WES) of single tooth-supported prostheses in the maxillary esthetic zone (13-23). MATERIALS AND METHODS: Forty-five patients were randomly assigned to one of the three treatment options (15 patients per group) receiving each one a different crown type: Porcelain fused to metal (PFM), monolithic zirconia, and lithium disilicate. Eight observers from each of four different specialties (Prosthodontists, Orthodontists, Periodontists, and Oral Surgeons) were recruited and assessed twice and four weeks apart (i.e., T1 and T2) 45 photographs of the single tooth-supported prosthesis using PES/WES and compared them with contralateral teeth. RESULTS: According to the ANOVA and post hoc tests, the zirconia crown type obtained the highest mean score by all observers, with a mean value of 16.70 ± 2.94. The prosthodontists and oral surgeons assigned the lowest mean score to PFM crowns, 13.03 ± 3.47 and 13.80 ± 3.17, respectively. Notably, the prosthodontists awarded the highest scores, specifically 17.50 ± 2.81 for the zirconia crowns. Intraobserver agreement was calculated utilizing the paired t-test. Pairwise comparisons between observers of different specialties revealed significant intraobserver agreement. Interclass correlation coefficient (ICC) scores were statistically significant among four specialties. No difference was detected concerning the interobserver agreement. CONCLUSIONS: The PES/WES index remains consistent across various observers from different specializations, yielding uniform results in the overall esthetic evaluation. Consequently, in light of the presented preliminary positive results, its use might also be considered for the esthetic assessment of single-tooth-supported prostheses. CLINICAL SIGNIFICANCE: The PES/WES index may be employed clinically to evaluate single tooth-supported prostheses as it emerged as a reproducible esthetic scoring system.

Full-Mouth Rehabilitation of a 15-Year-Old Girl Affected by a Rare Hypoparathyroidism (Glial Cell Missing Homolog 2 Mutation): A 3-Year Follow-Up.

OBJECTIVE: Familial isolated hypoparathyroidism is a rare genetic disorder due to no or low production of the parathyroid hormone, disturbing calcium and phosphate regulation. The resulting hypocalcemia may lead to dental abnormalities, such as enamel hypoplasia. The aim of this paper was to describe the full-mouth rehabilitation of a 15-year-old girl with chronic hypocalcemia due to a rare congenital hypoparathyroidism. CLINICAL CONSIDERATIONS: In this patient, in the young adult dentition, conservative care was preferred. Onlays or stainless-steel crowns were performed on the posterior teeth, and direct or indirect (overlays and veneerlays) were performed on the maxillary premolars, canines, and incisors, using a digital wax-up. The mandibular incisors were bleached. The treatment clearly improved the patient's oral quality of life, with fewer sensitivities, better chewing, and aesthetic satisfaction. The difficulties were the regular monitoring and the limited compliance of the patient. CONCLUSION: Despite no clinical feedback in the literature, generalized hypomineralized/hypoplastic teeth due to hypoparathyroidism in a young patient can be treated as amelogenesis imperfecta (generalized enamel defects) with a conservative approach for medium-term satisfactory results. HIGHLIGHTS: This study provides new insights into the management of enamel hypoplasia caused by familial isolated hypoparathyroidism, helping to improve patient outcomes in similar cases.

Evaluation and assessment of the survival of tooth implant supported prosthesis in tooth and implant supported rehabilitation cases with metal frameworks.

INTRODUCTION: Over the years, implant therapy has been a commonly used treatment option for individuals who are partially or totally edentulous, with a long-term success rate of over 90%. With significant advancements in biomaterials and technology, implant dentistry can now conduct prosthetic rehabilitations in the majority of patients catering to all types of needs. However, in order to meet the demands of a patient base that is always growing, new trends in implantology are emerging in recent years that are focused on minimally invasive surgery and financial sustainability. In certain clinical scenarios, connecting teeth and implants to support fixed partial prosthesis (FPPs) may be a predictable and workable course of treatment. MATERIALS AND METHODS: 22 patients were selected for this study who had tooth and implant supported prosthesis placed as a final restoration. Out of these 22 patients; 12 were male and 10 were female patients. Implants were placed following proper protocol and if grafting procedures were required they were carried out. A second stage surgical procedure was carried out and delayed loading protocols were followed. The statistical analysis was done using the IBM SPSS 24.0, Chicago, USA. The survival of the implants and teeth were measured by the Kaplan Meier survival scale. Bone loss was assessed at baseline(upon loading), 12 months and 24 months. RESULTS: The implant survival rate was measured at 6 months, 12 months, 18 months and 24 months. At 24 months, one implant showed failure, so the survival rate of the implants were 95.4%. Bone loss of 1 mm was seen around one implant at 12 months. Bone loss of 1 and 2 mm was present around two implants and one implant respectively at 24 months. CONCLUSION: From the results of this study, we can conclude that tooth implant supported prosthesis show very good survival when used in rehabilitation cases.

Mechanical stability of posterior implant-supported monolithic zirconia cantilever on titanium-base abutments. An in vitro study.

PURPOSE: Investigate survival and technical complications of two-unit posterior implant-supported cantilever made of monolithic zirconia on titanium-base abutments (Zr-TiB) vs. porcelain-fused-to-metal on castable gold abutments (PFM-GA) using two different implant connections, internal butt-joint (IBJ) and internal conical (IC). MATERIALS AND METHODS: Forty-eight implants (4.3 mm diameter) were divided into four groups (n = 12) to support 2-unit mandibular premolar cantilevers with two different materials (Zr-TiB vs. PFM-GA) and two connection types (IBJ vs. IC). Tested groups were as follows: (1) IBJ/Zr-TiB; (2) IBJ/PFM-GA; (3) IC/Zr-TiB; and (4) IC/PFM-GA. Specimens were thermomechanical aged (1,200,000 cycles, 98 N, 5-55°C) with occlusal axial load on the pontic. Catastrophic and non-catastrophic events were registered, and removal torque values measured before and after aging. Specimens surviving aging were subjected to loading until failure. Survival, total complication rates, torque loss (%), and bending moments were calculated. RESULTS: From 48 specimens, 38 survived aging. Survival rates significantly varied from 16.7% (IC/PFM-GA) to 100% (IBJ/Zr-TiB; IBJ/PFM-GA; IC/Zr-TiB) (p < .01). Internal conical connection revealed significantly higher torque loss (IC/ZrTiB - 67%) compared to internal butt-joint (IBJ/Zr-TiB - 44%; IBJ/PFM-GA - 46%) (p < .01). Bending moments were higher in internal butt-joint connections than in internal conical (p < .05). CONCLUSION AND CLINICAL IMPLICATIONS: Two-unit posterior implant-supported cantilever FDPs replacing mandibular premolars composed of monolithic zirconia on titanium-base abutments demonstrated higher mechanical stability compared to porcelain-fused-to-metal on castable gold abutments in this in vitro study. The internal conical connection combined with porcelain-fused-to-metal on gold abutments revealed a high number of failures; therefore, their clinical use may be considered cautiously for this indication.

Impact of fixed dental prosthesis on neuroimaging: assessment of artefacts.

Objectives: To determine the frequency and extent of artefacts in magnetic resonance imaging and/or computed tomography scans of head caused by fixed dental prosthesis. METHODS: The retrospective study was conducted at Aga Khan University Hospital from July to December 2021, and comprised magnetic resonance imaging and/or computed tomography scans from January 2015 to December 2020 of the head of individuals with existing fixed dental prosthetic work at the time of exposure. They were analysed for the presence of artefacts. The association between artefacts and the presence of fixed dental prosthesis was explored. Data was analysed using SPSS 23. RESULTS: Of the 297 images evaluated, 173 (58%) were magnetic resonance imaging scans, and 124(42%) were computed tomography scans. The most common artefacts was grade I 148(49.8%), followed by grade II 140(47.1%) and grade III 9(3%). There was no significant association between fixed dental prosthesis and the artefacts (p>0.05). Conclusion: There should be no reservations in placing fixed metal prosthesis in individuals on account of future brain scans.

Rehabilitating Long Edentulous Span by Using Pier Abutment as a Non-rigid Connector: A Case Report.

An abutment having edentulous space on both sides is referred to as a pier abutment. The rehabilitation of a patient whose primary concern when they first came to the hospital was missing teeth is discussed in this case report. When using a pier abutment for a fixed dental prosthesis, there is a problem with fulcrum and torqueing pressures at the intermediate abutment. Forces on the pier abutment may become localized as a result of using a rigid connector. It has been suggested that non-rigid connectors be used to overcome this. Here, using a non-rigid connector as a stress breaker resulted in less stress being placed on the prosthetic assembly and abutment. This article offers a clinical case report that details the use of a non-rigid connector in a pier abutment scenario for rehabilitation.

Influence of different convergence angles of abutment teeth and cement spaces on internal adaptation of anterior CAD-CAM fixed dental prostheses.

PURPOSE: The aim of this study was to investigate the influence of different convergence angles of abutment teeth and different cement spaces on internal adaptation of anterior fixed dental prostheses (FDPs) fabricated with a computer-aided design-computer-aided manufacturing (CAD-CAM) system. METHODS: Composite resin FDPs for 99 standardized maxillary central incisors were fabricated according to nine parameters: three total convergence angles (4 [DG4], 12 [DG12], and 20 degrees [DG20]) and three cement space settings (10 [CS10], 50 [CS50], and 90 µm [CS90]). Internal space values were measured with a cement space replica technique. The Kruskal-Wallis and Steel-Dwass tests were used to evaluate differences in the total convergence angles and luting agent spaces, respectively (α = 0.05). RESULTS: For all three cement spaces tested, the median marginal gap values between abutment teeth and FDPs decreased significantly as the total convergence angle increased (P < 0.05). For the CS10 and CS50 groups, the internal space values at the axial area increased significantly as the total convergence angles increased (P < 0.05). CONCLUSION: Total convergence angles of the abutment teeth and cement spaces affected the marginal and internal adaptation of anterior FDPs fabricated with a CAD-CAM system.

Fracture Resistance of Posterior Tooth-Supported Cantilever Fixed Dental Prostheses of Different Zirconia Generations and Framework Thicknesses: An In Vitro Study.

The rehabilitation of free-end situations is a frequent indication in prosthetic dentistry. Cantilever fixed dental prostheses (cFDPs) made of 1st and 2nd generation zirconia are one treatment option. Due to a unique gradient technology, combinations of different zirconium dioxide generations are thus feasible in one restoration. However, data about these materials are rare. The purpose of this study was therefore to investigate the fracture resistance and fracture modes of tooth-supported cFDPs fabricated from different zirconia materials (gradient technology) and different framework thicknesses. A total of 40 cFDPs were fabricated using the CAD/CAM approach and belonged to five test groups. The different groups differed in the yttria content, the proportion of the tetragonal/cubic phases, or in wall thickness (0.7 mm or 1 mm). After completion, the cFDPs were subjected to thermal cycling and chewing simulation (1.2 × 106 load cycles, 108 N load). Afterwards, cFDPs were statically loaded until fracture in a universal testing machine. A non-parametric ANOVA was compiled to determine the possible effects of group membership on fracture resistance. In addition, post-hoc Tukey tests were used for bivariate comparisons. The mean fracture loads under axial load application ranged from 288 to 577 N. ANOVA detected a significant impact of the used material on the fracture resistances (p < 0.001). Therefore, the use of cFDPs fabricated by gradient technology zirconia may not be unreservedly recommended for clinical use, whereas cFPDs made from 3Y-TZP exhibit fracture resistance above possible masticatory loads in the posterior region.

Initial damage and failure load of zirconia-ceramic and metal-ceramic posterior cantilever fixed partial dentures.

OBJECTIVES: The aim of this study was to compare failure load and initial damage in monolithic, partially veneered, and completely veneered (translucent) zirconia cantilevered fixed partial dentures (CFPDs), as well as completely veneered metal-ceramic CFPDs under different support and loading configurations. MATERIALS AND METHODS: Eight test groups with anatomically congruent CFPDs (n = 8/group) were fabricated, differing in CFPD material/support structure/loading direction (load applied via steel ball (Ø 6 mm) 3 mm from the distal end of the pontic for axial loading with a 2-point contact on the inner cusp ridges of the buccal and oral cusps and 1.3 mm below the oral cusp tip for 30° oblique loading): (1) monolithic zirconia/CoCr abutment teeth/axial, (2) monolithic zirconia/CoCr abutment teeth/oblique, (3) partially veneered zirconia/CoCr abutment teeth/axial, (4) partially veneered zirconia/CoCr abutment teeth/oblique, (5) completely veneered zirconia/CoCr abutment teeth/axial, (6) completely veneered CoCr/CoCr abutment teeth/axial (control group), (7) partially veneered zirconia/implants/axial, and (8) partially veneered zirconia/natural teeth/axial. Restorations were artificially aged before failure testing. Statistical analysis was conducted using one-way ANOVA and Tukey post hoc tests. RESULTS: Mean failure loads ranged from 392 N (group 8) to 1181 N (group 1). Axially loaded monolithic zirconia CFPDs (group 1) and controls (group 6) showed significantly higher failure loads. Oblique loading significantly reduced failure loads for monolithic zirconia CFPDs (group 2). Initial damage was observed in all groups except monolithic zirconia groups, and fractography revealed design flaws (sharp edges at the occlusal boundary of the veneering window) in partially veneered zirconia CFPDs. CONCLUSIONS: Monolithic zirconia CFPDs might be a viable alternative to completely veneered CoCr CFPDs in terms of fracture load. However, oblique loading of monolithic zirconia CFPDs should be avoided in clinical scenarios. Design improvements are required for partially veneered zirconia CFPDs to enhance their load-bearing capacity. CLINICAL RELEVANCE: Monolithic zirconia may represent a viable all-ceramic alternative to the established metal-ceramic option for CFPD fabrication. However, in daily clinical practice, careful occlusal adjustment and regular monitoring should ensure that oblique loading of the cantilever is avoided.

Perio-prosthodontic pontic site management, part II: Pontic site reconstruction strategies to enhance the esthetic and biological outcomes.

OBJECTIVE: Ridge deformities are present in most patients after tooth extraction; these defects make the management of future implant and pontic sites challenging to deal with. The restorative team should be able to diagnose and treat these deformities to allow for successful outcomes. Many approaches have been described to reconstruct pontic sites, each with specific indications. This article describes the different approaches to reconstructing pontic sites and their indications to allow for a proper esthetic and biological environment for future restorations. CLINICAL CONSIDERATIONS: Depending on the severity of the defect, location, and the esthetic necessity, pontic site enhancement can be done through different approaches, some requiring soft tissue grafting, hard tissue grafting, or both. Understanding the indications of the treatment options is essential to allow the clinician to make the right therapeutic decision and achieve the best possible perio-prosthodontic outcomes. CONCLUSIONS: An adequate balance between the soft tissue and prosthetics is essential to achieve successful results on implant-supported or tooth-supported fixed dental prostheses (FDPs). Selecting the right approach to treat ridge deformities is necessary to increase treatment success, reduce over-treatment, and create a biologically sound environment for restorations. CLINICAL SIGNIFICANCE: Pontic site enhancement through reconstructive surgery will allow for esthetically pleasing and biologically stable results, allowing restorations to emulate natural structures lost after tooth extraction.

Screw-retained ceramic-veneered/monolithic zirconia partial implant-supported fixed dental prostheses: A 5 to 10-year retrospective study on survival and complications.

PURPOSE: To assess the clinical performance of screw-retained, ceramic-veneered, monolithic zirconia partial implant-supported fixed dental prostheses (ISFDP) over 5-10 years and to evaluate implant- and prosthesis-related factors influencing treatment failure and complications. MATERIALS AND METHODS: Partially edentulous patients treated with screw-retained all-ceramic ISFDPs with 2-4 prosthetic units with a documented follow-up of ≥5 years after implant loading were included in this retrospective study. The outcomes analyzed included implant/prosthesis failure and biological/technical complications. Possible risk factors were identified using the mixed effects Cox regression analysis. RESULTS: A screened sample of 171 participants with 208 prostheses (95% of the restorations were splinted crowns without a pontic) supported by 451 dental implants were enrolled in this study. The mean follow-up duration after prosthesis delivery was 82.4 ±17.2 months. By the end of the follow-up period, 431 (95.57%) of the 451 implants remained functional at the implant level. At the prosthesis level, 185 (88.94%) of the 208 partial ISFDPs remained functional. Biological complications were observed in 67 implants (14.86%), and technical complications were observed in 62 ISFDPs (29.81%). Analysis revealed only emergence profiles (over-contoured) as a significant risk factor for implant failure (P<0.001) and biological complications (P<0.001). Full-coverage ceramic-veneered zirconia prostheses had a significantly greater chance of chipping (P<0.001) compared with buccal-ceramic-veneered or monolithic zirconia prostheses. CONCLUSIONS: Screw-retained ceramic-veneered, monolithic partial ISFDPs have a favorable long-term survival rate. Over-contoured emergence profile is a significant risk factor associated with implant failure and biological complications. Buccal-ceramic-veneered and monolithic zirconia partial ISFDPs lower the initial prevalence of chipping compared with a full-coverage veneered design.