To evaluate the marginal discrepancy of monolithic and veneered all-ceramic crown systems cemented on titanium (Ti) and zirconia implant abutments.Sixty customized implant abutments for a maxillary right central incisor were fabricated of Ti and zirconia (n = 30 of each) for an internal-connection implant system. All-ceramic crowns were fabricated using the following systems (n = 10 per group): monolithic with computer-aided design/computer-assisted manufacture (CAD/CAM) lithium disilicate (MLD), pressed lithium disilicate (PLD), or CAD yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP). The frameworks of the PLD and Y-TZP systems were manually veneered with a fluorapatite-based ceramic. The crowns were cemented to their implant abutments, and the absolute marginal discrepancy of the gap was measured before and after cementation. Data were analyzed statistically.Marginal discrepancies were significantly influenced by the crown system and by cementation, but the material did not significantly affect the results. Interaction terms were not significant. Y-TZP crowns on both Ti and zirconia abutments presented the smallest mean marginal discrepancies before (52.1 ± 17 μm and 56.2 ± 11 μm, respectively) and after cementation (98.7 ± 17 μm and 101.8 ± 16 μm, respectively). Before cementation, MLD crowns showed significantly larger mean marginal openings than PLD crowns on both Ti and zirconia abutments (75.2 ± 12 and 77.5 ± 13 μm for MLD, 52.1 ± 17 μm and 69.7 ± 8 μm for PLD, respectively). After cementation, both Ti and zirconia abutments with MLD crowns (113.5 ± 12 μm and 118.3 ± 14 μm, respectively) showed significantly larger values than with PLD crowns (98.7 ± 17 μm and 109.4 ± 9 μm, respectively).Manually veneered Y-TZP crowns demonstrated more favorable marginal fit on both Ti and zirconia implant abutments before and after cementation compared to those of MLD and PLD.
Abstract Objective To compare the implant–abutment connection microgap between computer‐aided design and computer‐aided manufacturing (CAD/CAM) milled or laser‐sintered cobalt–chrome custom abutments with or without ceramic veneering and titanium stock abutments with or without crown cementation. Material and Methods Six groups of six abutments each were prepared: (1) CAD/CAM cobalt–chrome custom abutments: milled, milled with ceramic veneering, laser‐sintered, and laser‐sintered with ceramic veneering (four groups: MIL, MIL‐C, SIN, and SIN‐C, respectively) and (2) titanium stock abutments with or without zirconia crown cementation (two groups: STK and STK‐Z, respectively). Abutments were screwed to the implants by applying 30 Ncm torque. All 36 samples were sectioned along their long axes. The implant–abutment connection microgap was measured using scanning electron microscopy on the right and left sides of the connection at the upper, middle, and lower levels. Data were analyzed using the Kruskal–Wallis test ( p < .05). Results Mean values (μm) of the microgap were 0.54 ± 0.44 (STK), 0.55 ± 0.48 (STK‐Z), 1.53 ± 1.30 (MIL), 2.30 ± 2.2 (MIL‐C), 1.53 ± 1.37 (SIN), and 1.87 ± 1.8 (SIN‐C). Although significant differences were observed between the STK and STK‐Z groups and the other groups ( p < .05), none were observed between the milled and laser‐sintered groups before or after ceramic veneering. The largest microgap was observed at the upper level in all groups. Conclusions Titanium stock abutments provided a closer fit than cobalt–chrome custom abutments. Neither crown cementation nor ceramic veneering resulted in significant changes in the implant–abutment connection microgap.
This study aimed to compare the marginal fit of 2 kinds of metal-ceramic crowns-crowns cast from commercially pure titanium and Procera titanium crowns.Ten copings of each type were prepared, veneered with low-fusing porcelain, and bonded with glass-ionomer cement. Marginal fit was assessed before and after cementation, and the data were analyzed statistically.There were significant differences among mean values of marginal fit between the groups. Cementation increases discrepancies in both groups.Casting titanium has resulted in the highest discrepancies in marginal fit of both groups.
Abstract Background There is a scarce knowledge on the accuracy of intraoral digital impression systems for dental implants. Purpose The purpose of this study is to evaluate the accuracy of a digital impression system considering clinical parameters. Materials and Methods A master model with six implants (27, 25, 22, 12, 15, 17) was fitted with polyether ether ketone scan bodies. Implant no. 25 was placed with 30° mesial angulation in relation to the vertical plane ( y axis), and implant no. 15 was positioned with 30° distal angulation. Implant no. 22 was placed 2 mm and no. 12, 4 mm below the gingiva. Experienced ( n = 2) and inexperienced operators ( n = 2) performed scanning ( L ava C hairside O ral S canner; 3 M ESPE, St Paul, MN, USA) at standard and high accuracy mode. Measurements involved five distances (27‐25, 27‐22, 27‐12, 27‐15, 27‐17). Measurements with high accuracy three‐dimensional coordinated measuring machine ( CMM ) of the master model acted as the true values. The data obtained were subtracted from those of the CMM values. Results Experience of the operator significantly influenced the results ( p = .000). Angulation ( p = .195) and depth of implant ( p = .399) did not show significant deviation from the true values. The mean difference between standard and high accuracy mode was 90 μm. Conclusions With the active wavefront sampling, technology‐based digital impression system training seems to be compulsory. Impressions of angulated implants may diminish the accuracy of the impression, yet the results were not significant.
The aim of this prospective study was to evaluate the clinical performance of zirconia-based posterior four-unit fixed dental prostheses (FDPs) after 4 years of clinical observation.Between 2006 and 2010, 10 patients (5 women, 5 men; mean age: 52.8 years) received 17 posterior four-unit FDPs. Two calibrated examiners evaluated the FDPs independently 1 week (baseline), 6 months, and 1, 2, 3, and 4 years after placement using California Dental Association (CDA) criteria. Periodontal status was assessed on both the abutment and contralateral control teeth using Plaque Index, Gingival Index, probing attachment level, and Margin Index parameters. Statistical analysis was performed using descriptive statistics and the Wilcoxon signed-rank test.Three restorations were lost because of fractures at their distal connectors after a mean clinical service of 25.3 months, and one abutment tooth was extracted because of vertical root fracture 23 months after cementation. Three FDPs presented chipping of a moderate size 1 week before framework fracture, and minor chipping was observed in 2 other FDPs 1 week and 36 months after cementation. After 4 years of clinical service, the cumulative survival rate of the posterior four-unit FDPs was 76.5%. No caries lesions were detected on the abutment teeth. The remaining restorations were judged to be satisfactory according to the CDA criteria. Periodontal parameters did not show significant differences between test and control teeth, but Gingival Index scores demonstrated a slight increase in inflammation in the distal abutments after 4 years (P = .016).The use of zirconia-based posterior four-unit FDPs should be restricted for patients with high esthetic demands, except in patients where at least 4 mm of height is available for connector thickness.
ABSTRACT Objective This case report presents the interdisciplinary retreatment of a patient with a worn full‐mouth rehabilitation using defect‐oriented restorations, horizontal preparations, and vertical dimension of occlusion (VDO) increase. Clinical Considerations A 58‐year‐old woman with a previous full‐mouth rehabilitation presented with worn dentition, loss of VDO, and reduced posterior support. Examination revealed signs of parafunctional habits, tetracycline‐stained teeth, and compromised aesthetics with exposed discolored teeth and open embrasure spaces. Additionally, the veneers showed wear and ceramic chipping. The retreatment started with a diagnostic phase, including a wax‐up and mock‐up to guide the treatment plan. Mucogingival surgery was performed to correct gingival recession according to the restorative margins established by the mock‐up. The full‐mouth rehabilitation involved increasing the VDO through anterior crowns and veneers, posterior overlays, and dental implant restoration. Horizontal chamfer preparations ensured sufficient thickness for the ceramic material, allowing for durable adhesive restorations. Conclusions The interdisciplinary approach, combining diagnostic, surgical, and prosthetic phases, enabled the successful retreatment of this complex case, restoring function and aesthetics. A 2‐year follow‐up confirmed the stability and positive outcomes of the rehabilitated dentition. Clinical Significance This interdisciplinary approach provides an effective strategy for managing complex full‐mouth rehabilitations, integrating aesthetics, function, and periodontal health through defect‐oriented preparation techniques.
To evaluate the accuracy of a digital impression system based on parallel confocal red laser technology, taking into consideration clinical parameters such as operator experience and angulation and depth of implants.A maxillary master model with six implants (located bilaterally in the second molar, second premolar, and lateral incisor positions) was fitted with six polyether ether ketone scan bodies. One second premolar implant was placed with 30 degrees of mesial angulation; the opposite implant was positioned with 30 degrees of distal angulation. The lateral incisor implants were placed 2 or 4 mm subgingivally. Two experienced and two inexperienced operators performed intraoral scanning. Five different interimplant distances were then measured. The files obtained from the scans were imported with reverse-engineering software. Measurements were then made with a coordinate measurement machine, with values from the master model used as reference values. The deviations from the actual values were then calculated. The differences between experienced and inexperienced operators and the effects of different implant angulations and depths were compared statistically.Overall, operator 3 obtained significantly less accurate results. The angulated implants did not significantly influence accuracy compared to the parallel implants. Differences were found in the amount of error in the different quadrants. The second scanned quadrant had significantly worse results than the first scanned quadrant. Impressions of the implants placed at the tissue level were less accurate than implants placed 2 and 4 mm subgingivally.The operator affected the accuracy of measurements, but the performance of the operator was not necessarily dependent on experience. Angulated implants did not decrease the accuracy of the digital impression system tested. The scanned distance affected the predictability of the accuracy of the scanner, and the error increased with the increased length of the scanned section.