Effect of connector height and retainer occlusal thickness on the fracture resistance of posterior 4-unit monolithic 5Y-TZP fixed partial dentures after thermomechanical aging.

STATEMENT OF PROBLEM: The connector height and retainer occlusal thickness of fixed partial dentures (FPDs) may affect restoration longevity. PURPOSE: The purpose of this in vitro study was to determine and compare the fracture resistance of 4-unit monolithic 5% yttria tetragonal zirconia polycrystal (5Y-TZP) FPDs made with different connector heights and retainer occlusal thicknesses after thermomechanical aging. MATERIAL AND METHODS: Forty test metal dies were duplicated from a master metal die containing 2 anatomic abutment preparations of the mandibular right first premolar and second molar for a 4-unit FPD. The dies were divided into 2 groups of 20 each for the fabrication of 4-unit FPDs, with 2-mm and 4-mm uniform connector heights at all 3 connectors, resulting in 6.3-mm2 and 12.6-mm2 connector areas. Each of these groups was further divided into 2 subgroups based on the occlusal thickness of the 2 retainers of 1 mm and 2 mm (n=10). Polyvinyl siloxane impressions of the test metal dies were made and poured in Type V dental stone. Laboratory scans were performed on all the stone dies, and 40 5Y-TZP FPDs (Ceramill Zolid FX) were designed and fabricated. Subsequently, all the FPDs were luted on to the metal dies with a self-adhesive resin cement. The FPDs were preloaded (400 000 mechanical cycles; 4000 thermocycles) using a mastication simulator and tested for axial compressive strength. Two-way analysis of variance (ANOVA) was used to examine the effect of connector and occlusal thicknesses on the fracture load (α=.05). The data were further assessed using the post hoc Tukey HSD multiple comparison test (α=.05). RESULTS: The mean fracture load values were between 737 N and 1563 N. Significant differences in the mean fracture load were found between the connector heights (601 N; P<.001) and occlusal thicknesses (225 N; P=.002), but the interaction of the 2 factors was not significant (P=.132) The Tukey post hoc analysis showed significant differences between the connector thicknesses groups (P<.01), but the occlusal thicknesses were found to be similar for the same connector height (P=.609) CONCLUSIONS: Connector height and occlusal retainer thickness influenced the fracture load of 4-unit monolithic 5Y-TZP FPDs after thermomechanical aging.

Double Crown-Retained Removable Prostheses Supported by Implants or Teeth and Implants: A Long-Term Clinical Retrospective Evaluation.

OBJECTIVES: The objective of this retrospective clinical study was to investigate the survival rates and complications of implant (I)-retained or tooth-implant (TI)-retained prostheses and abutments (teeth, implants) over a mean observation period of 11.26 years. The study also aimed to analyze the differences and complication rates between implant-retained double crown removable dental prostheses (I-DC-RDPs) versus tooth-implant-retained double crown removable dental prostheses (TI-DC-RDPs). MATERIAL AND METHODS: We reviewed the clinical data of 110 nonsmokers (mean age = 53.9 years) who received DC-RDPs in maxillary or mandibular arches. 153 teeth and 508 implants were used to restore partially edentulous (PE; TI-DC-RDPs; n = 53) and completely edentulous (CE; TI-DC-RDPs; n = 57) arches. Two designs of the distal extension were used: cantilevers (CANs) and saddles (SADs). Restorations were examined for abutment survival, mechanical, or biological complications. RESULTS: The 10-year survival rates were 99.3% (95% CI: 95.4-99.9%) for teeth and 99.3% (95% CI: 97.5-99.7%) for implants. The cumulative rates of TI- and I-RDPs free of technical complications were 77% and 86%, respectively. The risk of complications was not significantly different between the CAN and SAD subgroups of I-RDPs (p > 0.05). However, for TI-RDPs, technical complication risk was significantly higher in SAD type compared with CAN restorations (p = 0.02). CONCLUSIONS: I- and TI-DC-RDPs seem to be recommendable for restoration of CE or PE arches. The technical and biological complication rates were lower for I-DC-RDPs in the CE arches than for TI-DC-RDPs in the PE arches. Regarding the RDP design, CAN prostheses produced significantly fewer technical complications than did SAD prostheses.

Evaluation of Marginal and Internal Fit of a CAD/CAM Monolithic Zirconia-Reinforced Lithium Silicate Porcelain Laminate Veneer System.

PURPOSE: To evaluate the marginal and internal fit of monolithic computer-aided design/computer-aided manufacturing (CAD/CAM) ZLS (Vita Suprinity) glass ceramic porcelain laminate veneers (PLVs), in terms of marginal and internal gap widths, in comparison to monolithic lithium disilicate (LDS) [IPS e.max CAD] CAD/CAM veneers, and, also, to analyze the effect of incisal preparation designs (butt joint and chamfer), on the marginal and internal fit accuracy. MATERIALS AND METHODS: Forty dental stone dies poured from impressions made of two master metal dies with different incisal preparation designs were scanned to produce digital models. Forty ceramic veneers were designed and milled using the virtual models-10 ZLS butt joint, 10 ZLS chamfer, 10 LDS butt joint, and 10 LDS chamfer. The monolithic ceramic veneers produced were then subjected to marginal and internal gap width evaluation using X-ray nano-computed tomography and computerized digital analysis (n = 10). Descriptive analyses of data were performed and the influence of "material" and "preparation design" on the marginal and internal fit of veneers was assessed using 2-way ANOVA (α = 0.05). Bonferroni post-hoc multiple comparison tests were used to further analyze the interactions between the material and preparation design after adjusting the α value by Holm-Bonferroni method (α = 0.01). RESULTS: Mean marginal and internal gaps for ZLS PLVs were 65 ±11 µm and 112 ±14 µm for butt joint, and 100 ±24 µm and 100 ±21 µm for chamfer, respectively. Corresponding values for LDS PLVs were 78 ±25 µm and 114 ±17 µm for butt joint, and 104 ±18 µm and 106 ±7 µm for chamfer. Marginal gap and internal gap differences between ZLS and LDS PLVs were not significant (marginal gap: F = 1.786, p = 0.190; internal gap: F = 0.807, p = 0.375). However, the preparation designs (butt joint and chamfer) differed significantly in terms of marginal gaps (F = 23.797, p = 0.000), but not internal gaps (F = 3.703; p = 0.059). CONCLUSIONS: Butt joint margins produced better marginal accuracy in terms of marginal gap, compared to chamfers, for ZLS CAD/CAM laminate veneers.

Peri-implant mucosal response to implant-supported overdentures: A systematic review and meta-analysis.

OBJECTIVES: To systematically review and evaluate the effects of different types of attachments, implant numbers and loading protocols on the peri-implant mucosa of implant-supported overdentures (ISODs). BACKGROUND: The impact of peri-implant tissue health on the ISOD treatment outcome is unclear, and current evidence is inadequate on this aspect. MATERIALS AND METHODS: A systematic literature search for randomised controlled trials or prospective studies was conducted in indexed databases from 1995 to April 2020. The focused question was as follows: How does the peri-implant mucosa respond to implant-supported or implant-tissue-supported complete overdentures based on different types of attachments, implant numbers, and loading protocols, in terms of clinical outcomes achieved [plaque index (PI), gingival index (GI), probing pocket depth (PD) and bleeding index (BI)]? A random- or fixed-effects model was applied to measure the significance of standardised mean differences (SMD) of PD between the groups. RESULTS: Seventeen studies met the eligibility criteria. The SMD for PD between splinted/bar and unsplinted/stud attachments was 0.10 mm (95% CI: -0.27 to 0.47; P = .60) and between 2- and 4-implant groups was 0.15 mm (95% CI: -0.16 to 0.45; P = .34), which were not statistically significant. Significant difference (P = .003) was observed between immediate/early loading and delayed loading (SMD = 0.46 mm [95% CI: 0.16 to 0.75]). CONCLUSIONS: Probing depth for the immediate loaded implants was significantly higher than for the delayed loading group. No attachment type, implant number or loading protocol seemed to have a clear advantage over the other, in terms of other peri-implant mucosal outcome measures.

Fracture Resistance of Posterior Milled Nanoceramic Crowns after Thermomechanical Aging.

Fracture resistance is an important parameter used to predict the performance of indirect dental restorations. The purpose of this in vitro study was to assess the fracture load of posterior milled nanoceramic crowns, in comparison with the lithium disilicate crowns, after fatigue loading, for two different restoration occlusal thicknesses. Forty test metal dies were fabricated by duplicating a master metal model consisting of an anatomic abutment preparation of the maxillary first premolar for a single crown. The dies were divided into two groups of 20 each for the fabrication of nanoceramic (Lava Ultimate) and lithium disilicate (IPS e.max CAD) single crowns. Each material group was further divided into two sub-groups of 10 dies each, based on crown occlusal thickness, of 0.5-mm and 0.75-mm (n = 10). Dental Type V stone dies poured from polyvinyl siloxane impressions of the test metal dies were laboratory scanned in order to design and mill 40 ceramic crowns. The crowns were cemented on to the test metal dies with a self-adhesive resin luting cement. All crowns were thermocycled (2500 cycles) and mechanically loaded (250,000 cycles) in a chewing simulator followed by static loading until failure, and the values noted. The data were statistically analyzed by 2-way ANOVA and Tukey HSD post-hoc multiple comparison tests (α = 0.05). The mean fracture loads ranged from 1022 to 1322 N for nanoceramic crowns and from 1145 to 1441 N for the lithium disilicate crowns. Two-way ANOVA revealed insignificant differences between the nanoceramic and lithium disilicate crowns (p > 0.05) in terms of fracture load. Significant differences were noted in the fracture resistance of crowns based on occlusal thickness (303 N; p = 0.013) regardless of the material used. Multiple comparisons by Tukey HSD post-hoc test showed insignificant differences between the four material-occlusal thickness groups (p > 0.05). The nanoceramic crowns were found to be comparable with lithium disilicate crowns in terms of fracture load. The mean fracture loads of all of the tested crowns were within the normal physiological masticatory load limits. Based on the fracture-resistance results, nanoceramic crowns seem to be suitable for clinical use for the tested occlusal thicknesses.

Graftless Immediate Dual Implant Anatomic Placement With Immediate Provisional Passive Loading and Definitive Hybrid Crown for the Restoration of Mandibular Molar: A Clinical Report.

Immediate implant placement is well-known science and treatment in implant dentistry. It is a multitasking treatment consisting of surgical, prosthodontic, and periodontal aspects, implemented to obtain long-term clinically esthetic and functioning prosthesis. Immediate placement enables clinicians to reduce the number of surgical steps and shorter treatment duration. It has become a standard surgical protocol in modern implant practice. According to existing literature, dual implant placement can be done to avoid any cantilever effect in a single implant and to distribute masticatory forces. This clinical report describes the extraction of an infected mandibular right first molar, (46, Federation Dentaire Internationale) followed by immediate dual placement of dental implants in the rinsed and cleansed sockets. The tooth was atraumatically extracted from the socket, and the latter was prepared to the required depth, and endosseous implants were placed in both the mesial and distal sockets. This atraumatic graft-free operating technique and immediate placement resulted in the preservation of hard and soft tissues. It also increased the patient's comfort, acceptance, and satisfaction due to immediate loading with a provisional removable prosthesis. This was later replaced with a dual screw-retained hybrid implant crown.

The Effect of Nanosilver Sodium Fluoride on the Mechanical and Physiochemical Properties of Artificially Demineralised Dentin.

PURPOSE: To synthesise and characterise nanosilver sodium fluoride (NSSF) and assess the effect of applying this formulation in vitro on artificially demineralised root dentin lesions, compared with the application of silver diamine fluoride (SDF), sodium fluoride (NAF) or no treatment, in terms of mechanical, chemical and ultrastructural properties. MATERIALS AND METHODS: NSSF was prepared using 0.5 wt% chitosan solution. On 40 extracted human molars, the buccal aspect of the cervical thirds of roots were prepared and divided into 4 groups of 10 each: control (no treatment), NSSF, SDF and NaF (n = 10). The specimens were examined using scanning electron microscopy (SEM), atomic force microscopy (AFM), and x-ray photoelectron spectroscopy (XPS). Fourier transform infrared spectroscopy (FTIR), surface and cross-sectional microhardness and nano-indentation tests were performed to determine the mineral and carbonate content, microhardness, and nanohardness, respectively. Statistical analysis was performed to determine the differences between the different treatment groups for the set parameters using parametric and non-parametric tests. Tukey's and Dunnet's T3 post-hoc tests were further used for multiple comparisons between groups (α = 0.05). RESULTS: The control group (no treatment) was found to have statistically significantly lower mean scores for surface and cross-sectional microhardness compared with all other test groups (NaF, NSSF and SDF) (p < 0.05). Spearman's rank correlation test showed statistically insignificant differences between the mineral-to-matrix ratio (M:M) and carbonate content of all groups (p < 0.05). CONCLUSIONS: Treatment of root lesions with NSSF yielded comparable results to SDF and NaF under in-vitro conditions.

Zygomatic implant-retained fixed complete denture for an elderly patient.

Dental rehabilitation of a completely edentulous geriatric patient has always been a challenge to the clinician, especially in treating those with higher expectations and demands. Treatment duration and the amount of residual alveolar bone available are often important considerations when planning for dental implant-based fixed treatment for these patients. With the introduction of zygomatic implants, a graftless alternative solution has emerged for deficient maxillary bone with provision for immediate loading. This article describes the treatment of a completely edentulous elderly patient using zygomatic implants in conjunction with conventional implants. The implants were immediately loaded using a definitive acrylic resin fixed denture reinforced with a cast metal framework, to provide function and aesthetics.

Metal-ceramic screw-retained implant fixed partial denture with intraoral luted framework to improve passive fit.

Passive fit of a long-span screw-retained implant prosthesis is an important criteria for the success of the restoration. This article describes a technique for fabricating a ceramometal implant fixed dental prosthesis (FDP) for a long-span partially edentulous situation by altering the conventional screw-retained design. The possibility of a passive fit is maximized by intraoral luting of the cast frame to milled abutments, and the potential framework distortion during fabrication is compensated to a major extent. Retrievability is ensured by screw retention of the prosthesis to the implants. Compared with conventional porcelain fused to metal screw-retained FDP, this prosthesis is relatively inexpensive to fabricate.

Treatment Intricacies in Mandibular Implant-Supported Rehabilitation of a Patient With Down Syndrome: A Clinical Report.

Edentulism is considered a poor health condition and may compromise the quality of life. Prosthodontic replacement of missing teeth results in significant improvement of oral functions. Treating a patient with Down syndrome can pose clinical challenges in handling the emotional aspect as well as in rendering treatment. Careful oral analysis and diagnosis of the existing conditions in such patients will enable and pave the way for clinically acceptable treatment results. This clinical report describes the challenges encountered in the prosthodontic management of an edentulous young patient with Down syndrome.

Clinical outcomes of single crown and 3-unit bi-layered zirconia-based fixed dental prostheses: An upto 6- year retrospective clinical study: Clinical outcomes of zirconia FDPs.

OBJECTIVES: The aim of this retrospective clinical study was to evaluate the survival and the occurrence of technical and biological complications in bi-layered zirconia-based (Zi) single crown and 3-unit fixed dental prostheses (FDPs). Also, the study aimed to analyze the effects of tooth vitality (vital versus non-vital), abutment location (anterior versus posterior), and luting cement (self-adhesive resin versus resin-reinforced glass ionomer) on clinical outcomes. METHODS: A total of 147 prostheses (in 94 patients) placed by undergraduate dental students in a university dental center during the period 2015-2021 were examined clinically using modified United States Public Health Service (USPHS) and California Dental Association (CDA) criteria. The mean duration of follow-up was 37 months (range, 6 - 63 months) for the single crowns (n = 77) and 25 months (range, 6 - 68 months) for the 3-unit FDPs (n = 70). Data were descriptively analyzed to determine the types and rates of complications based on USPHS and CDA criteria. The Kaplan-Meier survival estimation method was used to determine the cumulative survival and success rates of the prostheses (α=0.05). Differences in clinical outcomes (survival or failure) according to tooth vitality, luting cement, and location were statistically analyzed using cross-tabulations and Ð¥2 test (α=0.05). RESULTS: The Kaplan-Meier cumulative survival rate was estimated as 96% for the Zi 3-unit FDPs after 5.5 years, and 90% for the Zi single crowns after 4.8 years. The 5-year estimated success rate was 68% for both 3-unit FDPs and single crowns. Seven (9.1%) 77Zi single crowns and 70 2 (2.9%) Zi 3-unit FDPs were recorded as failures with occlusal roughness being the most commonly-observed complication (crowns: 4 [5.6%]; 3-unit FDPs: 8 [11.4%]). In terms of clinical outcomes, statistically significant differences were found between all included vital and non-vital teeth (p = .006), and cement types (p = .028). Taking single crowns alone, significant differences in clinical outcomes according to tooth vitality were noted (p = .036), but not for PFDPs. The location of the prostheses did not produce any significant differences in the clinical outcomes, for both prostheses types independently or combined (p > .05). CONCLUSIONS: The estimated cumulative survival rates in this study for single crowns and 3-unit Zi FDPs concurred with the ranges reported in systematic reviews. Zi-based prostheses on vital teeth produced better clinical outcomes than those placed on non-vital teeth, and type of luting cement influenced the final clinical outcome. CLINICAL SIGNIFICANCE: Zi crowns and 3-unit PFDPs fabricated using the specific CAD-CAM system used in the controlled environment of this study showed good clinical performance with minimal veneer porcelain chipping. Root canal treated teeth seem to be at higher risk for failure of Zi prostheses compared with vital teeth.

Evaluation of the marginal fit of a CAD/CAM zirconia-based ceramic crown system.

PURPOSE: To evaluate the marginal fit of zirconia (Zi) CAD/CAM crowns in terms of gap and overhang compared to lithium disilicate (LDS) computer-aided design crowns, as well as the effect of finish line design on marginal accuracy. MATERIALS AND METHODS: Stone dies were acquired from two master metal dies (n = 20 each) with two different finish lines and were scanned to produce digital models. Ceramic crowns (ZS-Ronde Zi, KaVo and IPS e.max CAD LDS, Ivoclar Vivadent) were designed and milled on the resulting 40 dies: 10 Zi-shoulder, 10 Zi-chamfer, 10 LDSshoulder, and 10 LDS-chamfer. Marginal gap and overhang were evaluated at six designated margin locations. The data were obtained, and the influence of material and finish line on the marginal fit of crowns was assessed using two-way analysis of variance and Bonferroni multiple comparisons test (α = .05). RESULTS: Mean marginal gap and overhang on Zi crowns were 30 ± 14 µm and 79 ± 27 µm for the shoulder, respectively, and were 68 ± 34 µm and 104 ± 34 µm for the chamfer. The corresponding values for LDS crowns were 57 ± 22 µm and 74 ± 29 µm for the shoulder, and 62 ± 12 µm and 59 ± 27 µm for the chamfer. ANOVA revealed that the differences in marginal gap between the two materials were not significant (P > .05), but that the finish line effect and interaction were significant (P < .05). With regard to marginal overhang, significant differences were found between Zi and LDS crowns (P < .05), although the finish line geometries did not show any significant differences (P > .05). LDS crowns showed no differences between shoulder and chamfer margins for gap or overhang (P > .05), whereas significant differences were found in marginal gap between the Zi shoulder and chamfer margins (P lt; .005). CONCLUSION: In terms of marginal accuracy, shoulder margins produced smaller marginal gaps compared to chamfers for Zi CAD/CAM crowns.

Association of fit of partial denture metal framework with various framework design features using alginate as a final impression material: A prospective clinical study.

OBJECTIVES: To assess the fit of PRDP frameworks fabricated using alginate as a final impression material in metal stock trays, in terms of number of fabricated frameworks needed until realization of clinically adequate fit. Also, any association of framework fit achieved with its design features, namely major connector design, and numbers of guide plates and occlusal/incisal rests was investigated. METHODS: 147 partially dentate patients were provided with Co-Cr PRDPs, in single or both arches, by undergraduate dental students. Final impressions were made with alginate in metal stock trays. At metal framework try-in, clinical examinations were carried out by two prosthodontists and relevant information noted with regard to proper fit. The relationship between three PRDP design features and number of frameworks that needed to be made in each case to achieve satisfactory fit was determined using factorial analysis of variance (ANOVA) (α = 0.05). RESULTS: 86% (148) of the 173 frameworks fabricated were found to be clinically satisfactory at the first try-in visit (with or without any chairside adjustment). The remaining 14% (25) required new impressions for re-fabrication and passed at the second attempt. None of the examined design features were significantly associated with the number of construction attempts needed, for all 173 arches, or when maxillary and mandibular arches were considered independently (p > 0.05). CONCLUSIONS: PRDP design features were not associated with the level of accuracy of fit achieved. CLINICAL SIGNIFICANCE: Alginate in metal stock trays seems to be acceptable for final impressions of all types of Co-Cr PRDP designs with just 1 in 7 castings not fitting after chairside adjustment.

Effect of Finish Line Design on the Fit Accuracy of CAD/CAM Monolithic Polymer-Infiltrated Ceramic-Network Fixed Dental Prostheses: An In Vitro Study.

A polymer-infiltrated ceramic network (PICN) material has recently been introduced for dental use and evidence is developing regarding the fit accuracy of such crowns with different preparation designs. The aim of this in vitro study was to evaluate the precision of fit of machined monolithic PICN single crowns in comparison to lithium disilicate crowns in terms of marginal gap, internal gap, and absolute marginal discrepancies. A secondary aim was to assess the effect of finish line configuration on the fit accuracy of crowns made from the two materials. Two master metal dies were used to create forty stone dies, with twenty each for the two finish lines, shoulder and chamfer. The stone dies were scanned to produce virtual models, on which ceramic crowns were designed and milled, with ten each for the four material-finish line combinations (n = 10). Marginal gaps and absolute marginal discrepancies were evaluated at six pre-determined margin locations, and the internal gap was measured at 60 designated points using a stereomicroscope-based digital image analysis system. The influence of the material and finish line on the marginal and internal adaptation of crowns was assessed by analyzing the data using two-way analysis of variance (ANOVA), non-parametric, and Bonferroni multiple comparison post-hoc tests (α = 0.05). ANOVA revealed that the differences in the marginal gaps and the absolute marginal discrepancies between the two materials were significant (p < 0.05), but that those the finish line effect and the interaction were not significant (p > 0.05). Using the Mann-Whitney U test, the differences in IG for 'material' and 'finish line' were not found to be significant (p > 0.05). In conclusion, the finish line configuration did not seem to affect the marginal and internal adaptation of PICN and lithium disilicate crowns. The marginal gap of PICN crowns was below the clinically acceptable threshold of 120 µm.

Evaluation of accuracy of multiple dental implant impressions using various splinting materials.

PURPOSE: The aim of the present study was to compare the accuracy of casts obtained from nonsplinted and splinted direct impression techniques employing various splinting materials for multiple dental implants. MATERIALS AND METHODS: A reference model with four Nobel Replace Select implant replicas in the anterior mandible was fabricated with denture base heat-curing acrylic resin. Impressions of the reference model were made using polyether impression material by direct nonsplinted and splinted techniques. Impressions were divided into four groups: group A: nonsplinted technique; group B: acrylic resin-splinted technique; group C: bite registration addition silicone-splinted technique; and group D: bite registration polyether-splinted technique. Four impressions were made for each group and casts were poured in type IV dental stone. Linear differences in interimplant distances in the x-, y-, and z-axes and differences in interimplant angulations in the z-axis were measured on the casts using a coordinate measuring machine. RESULTS: The interimplant distance D1y showed significant variations in all four test groups (P = .043), while D3x values varied significantly between the acrylic resin-splinted and silicone-splinted groups. Casts obtained from the polyether-splinted group were the closest to the reference model in the x- and y-axes. In the z-axis, D2z values varied significantly among the three test groups (P = .009). Casts from the acrylic resin-splinted group were the closest to the reference model in the z-axis. Also, one of the three angles measured (angle 2) showed significant differences within three test groups (P = .009). Casts from the nonsplinted group exhibited the smallest angular differences. CONCLUSION: Casts obtained from all four impression techniques exhibited differences from the reference model. Casts obtained using the bite registration polyether-splinted technique were the most accurate versus the reference model, followed by those obtained via the acrylic resin-splinted, nonsplinted, and bite registration addition silicone-splinted techniques.

Evaluation of the marginal fit of a zirconia ceramic computer-aided machined (CAM) crown system.

STATEMENT OF PROBLEM: The marginal fit of crowns is a concern for clinicians, and there is no conclusive evidence of any one margin configuration yielding better results than others in terms of marginal fit. PURPOSE: The purpose of this study was to evaluate the marginal fit with respect to gap and overhang of Y-TZP (yttria-stabilized tetragonal zirconia polycrystals) ceramic crowns and compare them with lithium disilicate pressable and complete metal crowns. The influence of margin configuration on the marginal fit was also evaluated. MATERIAL AND METHODS: Impressions were made of premolar dies prepared with shoulders or chamfers with a 20-degree total occlusal convergence (n=30). Type IV stone dies were then distributed into test groups (n=10) for the fabrication of Cercon Y-TZP, IPS Empress II, and complete metal (noble type IV alloy) crowns. The crowns were then subjected to marginal gap and overhang evaluation at 6 designated margin locations using a computerized digital image analysis system. The data were calculated and statistically analyzed using 2-way ANOVA and Bonferroni post hoc tests (α=.05). RESULTS: The overall mean (SD) marginal gap at the marginal opening for the crowns was 66.4 (42.2) µm for Cercon, 36.6 (32.1) µm for IPS Empress II, and 37.1 (22.3) µm for complete metal (control). Overall mean (SD) overhang was -15.2 (47.5) µm for Cercon, -22.1 (34.7) µm for IPS Empress II, and 30.9 (31.3) µm for complete metal (control). The ANOVA revealed significant effects by material and no significant effects by marginal configuration for marginal gap. There were significant differences in the marginal overhang values between the 2 margins, but no significant differences were found between the material groups for overhang. CONCLUSIONS: The Cercon system showed significantly larger (P<.05) marginal gaps than both the IPS Empress II and complete metal (control) crowns, but no significant differences were found in marginal overhang among the 3 material groups. There was no significant difference in marginal gap between the 2 margin configurations, namely, chamfer and shoulder, for all test groups; however, there were significant differences (P<.05) in marginal overhang values between chamfer and shoulder margins.

Treatment of a maxillary dento-alveolar defect using an immediately loaded definitive zygoma implant-retained prosthesis with 11-month follow-up: a clinical report.

This article describes the dental implant-based rehabilitation of a partially edentulous patient with a unilateral maxillary dento-alveolar defect. A screw-retained prosthesis with a modified design was fabricated on zygomatic and regular dental implants. One section of the implant prosthesis has cemented crowns and the other section is conventional screw-retained. The design of the prosthesis overcame the hard and soft tissue deficit and provided the desired esthetics.

Full-arch metal-resin cement- and screw-retained provisional restoration for immediately loaded implants.

Abstract This article describes the clinical and laboratory procedures involved in the fabrication of laboratory-processed, provisional, screw-retained, implant-supported maxillary and mandibular fixed complete dentures incorporating a cast metal reinforcement for immediate loading of implants. Precise fit is achieved by intraoral luting of the cast frame to milled abutments. Effective splinting of all implants is attained by the metal substructure and retrievability is provided by the screw-retention of the prosthesis.

Edentulous arch treatment with a CAD/CAM screw-retained framework and cemented crowns: a clinical case report.

This article describes the rehabilitation of a completely edentulous patient using a milled titanium implant framework and cemented crowns. This combined approach significantly offsets unsuitable implant position, alignment, or angulation, while ensuring the easy retrievability, repair, and maintenance of the prosthesis. Hence, the dual advantage of cemented-retained crowns reproducing appropriate esthetics and function, irrespective of where the screw access openings are located in the substructure, can be obtained, along with the splinting effect and management of soft and hard tissue deficits achievable with a screw-retained framework.

Multi-Implant Impressions. To Splint or Not to Splint: A Critical Review.

This invited commentary reviews the use of splinting vs nonsplinting in implant impressions.