Purpose
The aim of this prospective cohort study was to investigate clinical and laboratory performance of implant‐supported reconstructions comparing the digital to the conventional workflow.
...Materials and Methods
Twenty study participants were treated in a cross‐over design for single‐tooth replacement in posterior sites, each with a customized titanium abutment plus computer‐assisted design and computer‐assisted manufacturing (CAD/CAM)‐zirconia‐suprastructure (test: digital workflow; n = 20) and a standardized titanium abutment plus PFM‐crown (control: conventional pathway; n = 20). Evaluation of the 40 reconstructions included: 1) feasibility of laboratory cross‐mounting of each abutment‐crown‐connection, and 2) assessment of adaptation time for clinical adjustments of interproximal and occlusal surfaces. Statistical analyses were performed using the exact Wilcoxon rank sum tests.
Results
Laboratory cross‐mounting was feasible for three reconstruction pairings revealing a 15% vice versa transfer success rate. All implant crowns could be provided successfully within two clinical appointments, independently of the workflow used. The mean clinical adjustment time was significantly lower (p < .001) for test reconstructions from the digital workflow with 2.2 min (standard deviation SD ± 2.1) compared with the ones from the conventional pathway with 6.0 min (SD ± 3.9).
Conclusions
The digital workflow was almost threefold more efficient than the established conventional pathway for fixed implant‐supported crowns. Clinical fitting could be predictably achieved with no or minor adjustments within the digital process of intraoral scanning plus CAD/CAM technology.
The aim of this cross-sectional study was to assess maximum restraining lip force (MLF), maximum voluntary bite force (MBF), and patient-related parameters to evaluate their influence on masticatory ...function in four groups of participants with different dental states.
Participants were recruited and assigned to one of four different groups depending on dental status: complete removable dental prostheses (CRDP group); edentulous with two-implant overdentures (IOD group); Kennedy Class I partial removable dental prostheses (PRDP group); or fully dentate (control group). A dental examination was performed and history taken. MLF was measured as the maximum withstood pulling force with three sizes of oral screens, MBF was evaluated using a digital force gauge, and masticatory performance was assessed using a two-color mixing ability test. Linear regression was used to determine the predictive effects of covariates on masticatory performance. Global and pairwise comparisons were also carried out.
A total of 68 participants with an average age of 69.3 ± 7.7 years were recruited. MLF depended on the screen size (P = .0004; Kruskal-Wallis) and increased with CRDP use, especially in challenging tasks, such as restraining the smallest screen. The highest MBF was found in dentate participants (P < .0001; Mann-Whitney). Analysis of variance (ANOVA) showed a global significant difference in masticatory performance between groups, with PRDP patients chewing better than CRDP patients. Dental state, time lapse since last tooth loss, and MBF predicted masticatory function.
Tooth loss significantly affects MBF and masticatory performance. Free-end saddles with a rotational axis in two-implant IODs and Kennedy Class I PRDPs may limit MBF and consequently masticatory performance. CRDP design should facilitate perioral muscular function.
Objective
To analyze the precision of fit of implant‐supported screw‐retained computer‐aided‐designed and computer‐aided‐manufactured (CAD/CAM) zirconium dioxide (ZrO) frameworks.
Materials and ...methods
Computer‐aided‐designed and computer‐aided‐manufactured ZrO frameworks (NobelProcera™) for a screw‐retained 10‐unit implant‐supported reconstruction on six implants (FDI positions 15, 13, 11, 21, 23, 25) were fabricated using a laser (ZrO‐L, N = 6) and a mechanical scanner (ZrO‐M, N = 5) for digitizing the implant platform and the cuspid‐supporting framework resin pattern. Laser‐scanned CAD/CAM titanium (TIT‐L, N = 6) and cast CoCrW‐alloy frameworks (Cast, N = 5) fabricated on the same model and designed similar to the ZrO frameworks were the control. The one‐screw test (implant 25 screw‐retained) was applied to assess the vertical microgap between implant and framework platform with a scanning electron microscope. The mean microgap was calculated from approximal and buccal values. Statistical comparison was performed with non‐parametric tests.
Results
No statistically significant pairwise difference was observed between the relative effects of vertical microgap between ZrO‐L (median 14 μm; 95% CI 10–26 μm), ZrO‐M (18 μm; 12–27 μm) and TIT‐L (15 μm; 6–18 μm), whereas the values of Cast (236 μm; 181–301 μm) were significantly higher (P < 0.001) than the three CAD/CAM groups. A monotonous trend of increasing values from implant 23 to 15 was observed in all groups (ZrO‐L, ZrO‐M and Cast P < 0.001, TIT‐L P = 0.044).
Conclusions
Optical and tactile scanners with CAD/CAM technology allow for the fabrication of highly accurate long‐span screw‐retained ZrO implant‐reconstructions. Titanium frameworks showed the most consistent precision. Fit of the cast alloy frameworks was clinically inacceptable.
Computer-assisted implant planning has become an important diagnostic and therapeutic tool in modern dentistry. This case report emphasizes the possibilities in modern implantology combining virtual ...implant planning, guided surgery with tooth and implant supported templates, immediate implant placement and loading.
A straight forward approach was followed for the mandible presenting with hopeless lower incisors. Diagnosis, decision making and treatment approach were based on clinical findings and detailed virtual three-dimensional implant planning. Extractions of the hopeless mandibular incisors, immediate and guided implant placement of six standard implants, and immediate loading with a provisional fixed dental prosthesis (FDP) were performed fulfilling patient's functional and esthetic demands. The final computer assisted design / computer assisted manufacturing (CAD/CAM) FDP with a titanium framework and composite veneering was delivered after 6 months. At the 1-year recall the FDP was free of technical complications. Stable bony conditions and a healthy peri-implant mucosa could be observed.
Computer assisted implantology including three-dimensional virtual implant planning, guided surgery, and CAD/CAM fabrication of provisional and final reconstructions allowed for a concise treatment workflow with predictable esthetic and functional outcomes in this mandibular full-arch case. The combination of immediate implant placement and immediate loading was considerably more complex and required a high level of organization between implantologist, technician and patient. After the usage of a first tooth-supported surgical template with subsequent extraction of the supporting teeth, a second surgical template stabilized on the previously inserted implants helped to transfer the planned implant position in the extraction sites with a guided approach.
Statement of problem The increasing demand by patients for esthetic and metal-free restorations has driven the development of ceramic restorations with good esthetic and mechanical stability. Recent ...clinical studies have investigated the use of zirconium dioxide as a core material for complete crowns and computer-aided-design/computer-aided-manufacturing fabricated restorations. Purpose The aim of this systematic review was to evaluate the clinical survival rates of porcelain-fused-to-zirconia (PFZ) single crowns on anterior and posterior teeth and to compare them with metal ceramic (MC) crowns. Material and methods A systematic search was conducted with PubMed and manual research to identify literature written in English that refers to in vivo studies published from January 1, 1950 through July 1, 2011. Clinical trials that evaluated PFZ and MC single crowns on natural teeth were selected for further analysis. Titles and/or abstracts of articles identified through the electronic searches were reviewed and evaluated for appropriateness. In addition, a hand search of relevant dental journals was peformed, and reference lists of culled articles were screened to identify publications. Results The search resulted in a total of 488 initial matches. Nineteen studies with a total of 3621 crowns met the inclusion criteria. The survival rates of PFZ crowns (total 300) ranged from 92.7% to 100% for a follow-up time of 24 to 39 months, whereas those of MC crowns (total 3321) ranged from 70% to 100% for a follow-up time of 12 to 298 months. Studies that reported long-term results were found only for the MC crown group. Conclusions The scientific clinical data available to compare PFZ and MC crowns are limited. The survival rates may well be influenced by the selection and appropriate use of the veneering ceramic, and, therefore, additional prospective long-term clinical trials are necessary to draw reliable conclusions.
Objective
To compare the precision of fit of long‐span vs. short‐span implant‐supported screw‐retained fixed dental prostheses (FDPs) made from computer‐aided‐design/computer‐aided‐manufactured ...(CAD/CAM) titanium and veneered with ceramic. The null hypothesis was that there is no difference in the vertical microgap between long‐span and short‐span FDPs.
Materials and methods
CAD/CAM titanium frameworks for an implant‐supported maxillary FDP on implants with a flat platform were fabricated on one single master cast. Group A consisted of six 10‐unit FDPs connected to six implants (FDI positions 15, 13, 11, 21, 23, 25) and group B of six 5‐unit FDPs (three implants, FDI positions 21, 23, 25). The CAD/CAM system from Biodenta Swiss AG (Berneck, Switzerland) was used for digitizing (laser scanner) the master cast and anatomical CAD of each framework separately. The frameworks were milled (CAM) from a titanium grade V monobloc and veneered with porcelain. Median vertical distance between implant and FDP platforms from the non‐tightened implants (one‐screw test on implant 25) was calculated from mesial, buccal, and distal scanning electron microscope measurements.
Results
All measurements showed values <40 μm. Total median vertical microgaps were 23 μm (range 2–38 μm) for group A and 7 μm (4–24 μm) for group B. The difference between the groups was statistically significant at implant 21 (P = 0.002; 97.5% CI −27.3 to −4.9) and insignificant at implant 23 (P = 0.093; −3.9 to 1.0).
Conclusions
CAD/CAM fabrication including laboratory scanning and porcelain firing was highly precise and reproducible for all long‐ and short‐span FDPs. While all FDPs showed clinically acceptable values, the short‐span FDPs were statistically more precise at the 5‐unit span distance.
ABSTRACT
Objectives: To analyze computer‐assisted diagnostics and virtual implant planning and to evaluate the indication for template‐guided flapless surgery and immediate loading in the ...rehabilitation of the edentulous maxilla.
Materials and Methods: Forty patients with an edentulous maxilla were selected for this study. The three‐dimensional analysis and virtual implant planning was performed with the NobelGuide™ software program (Nobel Biocare, Göteborg, Sweden). Prior to the computer tomography aesthetics and functional aspects were checked clinically. Either a well‐fitting denture or an optimized prosthetic setup was used and then converted to a radiographic template. This allowed for a computer‐guided analysis of the jaw together with the prosthesis. Accordingly, the best implant position was determined in relation to the bone structure and prospective tooth position. For all jaws, the hypothetical indication for (1) four implants with a bar overdenture and (2) six implants with a simple fixed prosthesis were planned. The planning of the optimized implant position was then analyzed as follows: the number of implants was calculated that could be placed in sufficient quantity of bone. Additional surgical procedures (guided bone regeneration, sinus floor elevation) that would be necessary due the reduced bone quality and quantity were identified. The indication of template‐guided, flapless surgery or an immediate loaded protocol was evaluated.
Results: Model (a) – bar overdentures: for 28 patients (70%), all four implants could be placed in sufficient bone (total 112 implants). Thus, a full, flapless procedure could be suggested. For six patients (15%), sufficient bone was not available for any of their planned implants. The remaining six patients had exhibited a combination of sufficient or insufficient bone. Model (b) – simple fixed prosthesis: for 12 patients (30%), all six implants could be placed in sufficient bone (total 72 implants). Thus, a full, flapless procedure could be suggested. For seven patients (17%), sufficient bone was not available for any of their planned implants. The remaining 21 patients had exhibited a combination of sufficient or insufficient bone.
Discussion: In the maxilla, advanced atrophy is often observed, and implant placement becomes difficult or impossible. Thus, flapless surgery or an immediate loading protocol can be performed just in a selected number of patients. Nevertheless, the use of a computer program for prosthetically driven implant planning is highly efficient and safe. The three‐dimensional view of the maxilla allows the determination of the best implant position, the optimization of the implant axis, and the definition of the best surgical and prosthetic solution for the patient. Thus, a protocol that combines a computer‐guided technique with conventional surgical procedures becomes a promising option, which needs to be further evaluated and improved.
To evaluate technical complications and failures of zirconia-based fixed prostheses supported by implants.
Consecutive patients received zirconia-based single crowns (SCs) and fixed dental prostheses ...(FDPs) on implants in a private clinical setting between 2005 and 2010. One dentist performed all surgical and prosthetic procedures, and one master technician performed and coordinated all laboratory procedures. One-piece computer-aided design/ computer-assisted manufacture technology was used to fabricate abutments and frameworks, which were directly connected at the implant level, where possible. All patients were involved in a recall maintenance program and were finally reviewed in 2012. Data on framework fractures, chipping of veneering ceramics, and other technical complications were recorded. The primary endpoint was failure of the prostheses, ie, the need for a complete remake. A life table analysis was calculated.
A total of 289 implants supported 193 zirconia-based prostheses (120 SCs and 73 FDPs) in 127 patients (51 men, 76 women; average age: 62.5 ± 13.4 years) who were reviewed in 2012. Twenty-five (13%) prostheses were cemented on 44 zirconia abutments and 168 (87%) prostheses were screw-retained directly at the implant level. Fracture of 3 frameworks (1 SC, 2 FDPs) was recorded, and significant chipping resulted in the remake of 3 prostheses (1 SC, 2 FDPs). The 7-year cumulative survival rate was 96.4% ± 1.99%. Minor complications comprised 5 loose screws (these were retightened), small chips associated with 3 prostheses (these were polished), and dislodgement of 3 prostheses (these were recemented). Overall, 176 prostheses remained free of technical problems.
Zirconia-based prostheses screwed directly to implants are clinically successful in the short and medium term.
Purpose
The study aims to evaluate three‐dimensionally (3D) the accuracy of implant impressions using a new resin splinting material, “Smart Dentin Replacement” (SDR).
Materials and Methods
A ...titanium model of an edentulous mandible with six implant analogues was used as a master model and its dimensions measured with a coordinate measuring machine. Before the total 60 impressions were taken (open tray, screw‐retained abutments, vinyl polysiloxane), they were divided in four groups: A (test): copings pick‐up splinted with dental floss and fotopolymerizing SDR; B (test): see A, additionally sectioned and splinted again with SDR; C (control): copings pick‐up splinted with dental floss and autopolymerizing Duralay® (Reliance Dental Mfg. Co., Alsip, IL, USA) acrylic resin; and D (control): see C, additionally sectioned and splinted again with Duralay. The impressions were measured directly with an optomechanical coordinate measuring machine and analyzed with a computer‐aided design (CAD) geometric modeling software. The Wilcoxon matched‐pair signed‐rank test was used to compare groups.
Results
While there was no difference (p = .430) between the mean 3D deviations of the test groups A (17.5 μm) and B (17.4 μm), they both showed statistically significant differences (p < .003) compared with both control groups (C 25.0 μm, D 19.1 μm).
Conclusions
Conventional impression techniques for edentulous jaws with multiple implants are highly accurate using the new fotopolymerizing splinting material SDR. Sectioning and rejoining of the SDR splinting had no impact on the impression accuracy.
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