Journal of Prosthetic Dentistry最新文献

Statement of problem: Extraoral photogrammetry (PG) systems provide a reliable method for recording implant positions; however, the accuracy of an intraoral PG system integrated into an intraoral scanner (IOS) system remains unknown.

Purpose: The purpose of this in vitro study was to compare the accuracy of complete arch implant scans captured by using 4 extraoral and 1 intraoral PG system.

Material and methods: An edentulous cast with 6 implant abutment analogs (MultiUnit Abutment Plus Replica) was digitized (T710). Five groups were created depending on the PG system used to capture complete arch implant scans: 4 extraoral PG systems, PIC (PIC System), Icam4D (Imetric), Grammee (BlueSkyBio), OxoFit (Oxo), and 1 intraoral PG device, Elite (Shining 3D) (n=30). In each group, the corresponding optical markers were placed on the implant abutment analogs of the reference cast, and 30 consecutive scans were recorded. Euclidean linear and angular measurements were obtained on the digitized reference cast and used to compare the discrepancies with the same measurements obtained on each experimental scan. One-way ANOVA and Tukey tests were used to analyze the trueness data. The Levene test was used to analyze precision values (α=.05).

Results: Significant linear trueness (P<.001) and precision (P<.001) discrepancies were found among the groups. PIC and Icam4D groups obtained significantly better linear trueness than the other PG systems, and PIC obtained the best linear precision. The linear discrepancies ranged from 17 to 30 µm. Significant angular trueness (P<.001) and precision (P<.001) differences were revealed among the groups. The Grammee obtained the best angular trueness, while PIC obtained the best angular precision. The angular discrepancies ranged from 0.17 to 0.34 degrees.

Conclusions: The PG system influenced the trueness and precision of complete arch implant scans. The intraoral PG obtained accuracy values similar to those of the 2 extraoral PGs (Grammee and OxoFit). The discrepancies measured among the systems may not be clinically significant.

Statement of problem: Digitized analog records have been used for the superimposition of intraoral and facial scans. However, the discrepancy in the registration between the digitized occlusal records contained on extraoral scan bodies and the maxillary virtual cast remains uncertain.

Purpose: The purpose of this in vitro study was to evaluate the effect of the registration method, edentulous area, and tooth anatomy on the accuracy of the alignment between the digitized extraoral scan body (ESB) and the maxillary virtual cast.

Material and methods: A scannable ESB and a set of 8 maxillary casts (2 completely dentate simulating unworn and worn tooth anatomy, 5 partially edentulous, and 1 completely edentulous were printed (Pro 95S; SprintRay). Four zirconia markers were attached to the index of the ESB and each of the evaluated casts. Each cast was positioned into the tray of the ESB using occlusal registration material (O-Bite; DMG). The ESB and each corresponding evaluated cast were digitized by using a calibrated laboratory scanner (T710; Medit). Then, each cast and index of the ESB were scanned separately by using the same scanner (n=10). Using a CAD software program, each virtual cast was attached to the ESB 10 times by using 3 different alignment methods: an analog using an iterative closest points (ICP) algorithm and 2 semimanual alignments using a best-fit algorithm for the entire data set with or without including the edentulous areas. A metrology software program was used to measure the linear distance between the corresponding gauge balls and the angulation between the planes defined by the markers on the cast and the ESB. The measurements from the scans of the casts attached to the tray were used as a reference to calculate the discrepancies in each experimental group. Α P value threshold of <.05 was used to determine statistical significance.

Results: The best-fit algorithm registration method produced better trueness and precision than the manual point-to-point registration (P<.05). When the edentulous areas were not included in the analog surface record, the trueness and precision of the best-fit algorithm were significantly worse (P<.05). In respect of tooth anatomy, no significant difference in trueness and precision was found among the investigated groups (P>.05). The completely dentate groups presented significantly better trueness than the edentulous groups (P<.05).

Conclusions: The accuracy of the registration between digitized occlusal surface scans and digital casts was influenced by the registration method, as well as by the location and extent of the edentulous areas.

Statement of problem: Marginal gaps and the internal adaptation of a fixed dental prosthesis are important parameters related to a successful clinical outcome. Several methods have been used to measure these 2 parameters. In addition to conventional analog methods, digital methods have recently been developed. Nevertheless, statistical comparisons of these different approaches are scarce.

Purpose: The purpose of this study was to evaluate the results of the various measuring methods reported in the current literature and compare their results.

Material and methods: An electronic literature search comprising articles published from January 1990 to June 2023was conducted through the MEDLINE (PubMed) and Web of Science databases. After a quality assessment screening, 17 articles were identified for inclusion in the meta-analysis. Data were used for the random-effects model, forest plots were drawn, and significance tests were conducted in the meta-analysis software program of the Cochrane Collaboration (RevManv5.3.5). Additionally, heterogeneity tests and a risk of bias analysis were performed.

Results: In the general comparison of conventional and digital methods, the data did not show significant differences, and the results presented low homogeneity. When the cross-sectional method (CSM) was compared under a scanning electron microscope with the silicone replica Geomagic software program (SRG) method, CSM recorded significantly smaller gap values than SRG and presented high homogeneity. Meanwhile, in the comparison of CSM with the silicone replica technique (SRT) and the triple scan method (TSM), CSM recorded larger gap values than SRT and TSM, and the data did not show a significant difference. All of these results presented low homogeneity.

Conclusions: A comparison of most techniques revealed no significant differences in the internal and marginal gaps, except for SRG, which recorded significantly smaller gaps than CSM. However, the conclusions of these findings are limited because of concerns about bias and heterogeneity and because the found marginal gap data are just one way to assess the consistency and reliability of each method.

Statement of problem: Although intraoral scanners have been increasingly utilized as alternatives to conventional impression techniques, their precision in capturing the complex anatomy of prepared widened root canals, essential for post placement after endodontic treatment, remains underexplored.

Purpose: The purpose of this in vitro study was to assess the efficacy of different intraoral scanners in scanning widened root canals. The study analyzed the depth (mm) and surface area scanned (mm²) and compared 2 scanning techniques.

Material and methods: Ten human single-rooted second premolars were endodontically treated, sectioned perpendicularly to their long axis, subsequently widened, and embedded in 3-dimensionally printed casts. Each specimen was scanned by all 3 intraoral scanners, TRIOS 3, MEDIT i600, and PRIMESCAN, and an impression was subsequently made with acrylic resin to serve as a control. Two scanning techniques were used: conventional, with rectilinear scanning movements, and oscillatory, with rotating oscillating movements over the entire piece to be scanned. The data were analyzed using repeated-measure ANOVA with the Tukey post hoc test for comparison among groups (α=.05).

Results: Significant differences in scanning depth were observed among techniques (P<.001), with the oscillatory method achieving greater depth overall, especially with PRIMESCAN. An interaction between scanner and technique (P<.001) identified their combined impact on accuracy, with PRIMESCAN also capturing the largest surface areas.

Conclusions: Regarding the scanned surface area, the oscillatory technique showed greater effectiveness in all groups, while PRIMESCAN obtained a greater area in the conventional technique.

Statement of problem: Intraorally scanning the palate may affect the accuracy of digital implant scans depending on the maxillary arch anatomy (arch form, palatal vault depth) and the number of implants.

Purpose: The purpose of this in vitro study was to investigate the effect of scanning the palate on the accuracy of maxillary implant complete arch scans with 3 different palatal vault depths and 3 arch forms and also the number of implants.

Material and methods: A maxillary edentulous cast was scanned using a desktop scanner and imported into a computer aided design and computer aided manufacturing (CAD-CAM) software program to create a digital control model. That model was duplicated and modified to create different digital control models that differ in palate depth (shallow, medium, deep), arch form (ovoid, square, tapered), and number of implants (4 or 6). The 18 digital files were used to print 18 physical casts that were scanned using 2 different techniques - palate-less (UP) and palate stitching (SP) - using an intraoral scanner. Each scanning technique was repeated 7 times, and a total of 252 scans (SP and UP) were obtained from the models and superimposed over the corresponding original digital control using an industrial metrology software program to obtain trueness and precision values for each scanning technique according to the different variables. The Kruskal-Wallis test was used to detect the differences in trueness and precision among the experimental groups and with different variables.

Results: No significant association was found between the maxillary complete arch scanning technique (SP and UP) and the accuracy of implant complete arch maxillary digital scans (P=.167). Both scanning methods (SP and UP) were significantly different in trueness and precision when compared with the control group (P<.001). The accuracy between the scans was not affected by arch form or number of implants (P>.05). However, shallow complete arch maxillary scans were more accurate than medium depth scans (P<.001), although the difference was small.

Conclusions: When 3 different palatal depths, 3 different arch forms, 4 versus 6 implants, and SP versus UP scans were examined, none of these variables were found to affect the accuracy of maxillary complete arch digital scans.

Statement of problem: Scientific data on the long-term clinical performance of cantilever zirconia resin-bonded fixed dental prostheses (RBFDPs) replacing missing incisors are lacking.

Purpose: The purpose of this clinical study was to evaluate the survival, retention, and success rates of cantilever zirconia ceramic RBFDPs replacing missing maxillary and mandibular incisors.

Material and methods: A total of 258 patients had been provided with 328 cantilever zirconia RBFDPs to replace missing incisors in the period 2001 to 2022. Tooth preparation was minimal, limited to the enamel, and consisted of a veneer design. All restorations had been adhesively bonded, and the patients were periodically followed up. The Kaplan-Meier test was applied to assess survival, retention, and success rates. The Log-Rank test was used to compare the aforementioned rates among 3 groups (Group C: maxillary central incisor RBFDPs; Group L: maxillary lateral incisor RBFDPs; and Group M: mandibular central and lateral RBFDPs).

Results: Seventeen patients could not be evaluated because of loss of contact (dropout rate 6.6%). A total of 310 cantilever zirconia RBFDPs inserted in 241 patients were followed for a mean period of 85 ±55 months. A 15-year survival rate of 97.3% (confidence interval [CI]: 95.7%-98.9%) was calculated using the Kaplan-Meier method. Over the observation time, 17 RBFDPs debonded, resulting in a retention rate of 82.3% (CI: 77.2%-87.4%), of which 16 were adhesively rebonded with no further complications. Pontic location did not statistically affect the survival or retention rates (P>.05) but did significantly affect the success rate (P=.021).

Conclusions: Zirconia ceramic cantilever RBFDPs provided a minimally invasive treatment option for replacing missing maxillary and mandibular incisors with excellent clinical outcomes.

Double crown removable partial dentures (RPDs) are suitable treatment options for patients with a significantly reduced dentition. The prognosis for these prostheses is greatly influenced by the number, position, and distribution of the abutment teeth. If the remaining natural teeth are unfavorably positioned, placing implants in strategic positions may enhance the long-term prognosis of the prosthesis. In this clinical report, 3 patients with a reduced dentition were treated with combined tooth-implant-supported double crown RPDs using a gold electroforming system. During an up to 18-year follow-up, the implants and natural abutment teeth showed no pathologic signs. By following the 3 strategies for placing supplementary implants outlined in this clinical report, the combined tooth-implant-supported double crown RPD using a gold electroforming system can be highly recommended.

Statement of problem: Low-pressure airborne-particle abrasion has been used to improve the adhesion of zirconia to resin cement. However, whether a polyelectrolyte multilayer can be used to reduce bacterial adhesion to abraded zirconia is unclear.

Purpose: The purpose of this in vitro study was to evaluate whether polyelectrolyte multilayers added to airborne-particle abraded zirconia can minimize biofilm development.

Material and methods: Commercially available zirconia powders with yttria content between 3 and 5 mol% were isostatically pressed into Ø20-mm disks and sintered at 1450 °C for 2 hours (n=8). Untreated specimens were compared with airborne-particle abraded ones. Specimens with 3 mol% yttria were further coated with polyelectrolyte multilayers (n=4). The surfaces were characterized by measuring the roughness, hydrophobicity, and surface charge using profilometry, atomic force microscopy, tensiometry, and electrokinetic analyzer, respectively. The extent of bacterial adhesion was determined using spectrophotometry and scanning electron microscopy. Data were analyzed with a single-factor ANOVA and F-test for variance (α=.05).

Results: The airborne-particle abrasion of zirconia increased the surface roughness, which led to the pronounced adhesion of Streptococcus mutans. However, polyelectrolyte multilayer coatings made of chitosan and pol(yacrylic acid) reduced the extent of bacterial adhesion, especially in as-sintered specimens, with 70% fewer adhered bacteria than airborne-particle abraded specimens. The effect of polyelectrolyte multilayer coating on the airborne-particle abraded series was greatest with the poly(acrylic acid)-terminating specimens, with 50% fewer adhered bacteria than the uncoated ones.

Conclusions: Airborne-particle abraded zirconia specimens coated with biocompatible polyelectrolyte multilayer coatings with a negatively charged terminating layer were associated with a 50% reduction in bacteria adhesion compared with uncoated specimens.

This technique involves intraoral scanning of the dentition, open occlusal cone beam computed tomography (CBCT) of the jaw cyst, and digital data from the recording of the decompression window and adjacent teeth to construct 3-dimensional (3D) images of the jaw cyst-mucosa-dentition after decompression. Following the digital design of the crown, clasp arms, and multilayer porous channels, a plug with good retention, adequate drainage, and high patient satisfaction was digitally printed with elastic resins in a single visit.