The International journal of prosthodontics最新文献

Purpose: To develop a system for assessment of the status of a tooth to receive a full coverage crown and depict it on a measurable scale, and to validate its use by assessing examiner reproducibility.

Methods: The index was developed based on the inputs from experts in the field with a consensus on factors (4 periodontal, 2 endodontic, and 4 prosthodontic), stages of severity (stage 1 to stage 4), assigned scores, and relative weights pertaining to varied clinical scenarios. Based on the selection of factor-stage combination, an overall tooth crownability index (TCI) score along with three-factor scores were computed. The validation study included clinical and radiological assessment of cases based on the index criteria by four independent examiners (periodontist, prosthodontist, endodontist, and general practitioner).

Results: Forty teeth were assessed. The distribution of repeated selection by the examiners was quite identical to the initial (kappa = 0.93). There was no statistically significant difference in the mean scores of examiners in TCI and factorial scores. An excellent agreement between the measurements was observed among the examiners (ICC =0.993; Crohnbach α = 0.993).

Conclusions: A tooth crownability index has been developed for a tooth to receive a full coverage crown which has an excellent agreement and good reproducibility among the examiners. TCI will serve as a baseline tool in treatment plan decision-making based on the status of the teeth and in research for evaluating the efficacy of various treatment options available (standard criteria for outcome assessment).

Purpose: To evaluate the surface characteristics, accuracy (trueness and precision), and dimensional stability of tooth preparation dies fabricated using conventional gypsum and direct light processing (DLP), stereolithography (SLA), and polymer jetting printing (PJP) techniques.

Materials and methods: Gypsum preparation dies were replicated according to the reference data and imported into DLP, SLA, and PJP printers, and the test data were obtained by scanning after 0, 1, 3, 7, 14, 28, and 42 days. After analyzing the surface characteristics, a best-fit algorithm between the test and the reference data was used to evaluate the accuracy and dimensional stability of the preparation dies. The data were analyzed by one-way analysis of variance and Tukey test or Kruskal-Wallis H test (α = .05).

Results: Compared with the gypsum group (3.61 ± 0.59 μm), the root mean square error (RMSE) values of the SLA group (5.33 ± 0.48 μm) was rougher (P < .05), the PJP group (2.43 ± 0.37 μm) was smoother (P < .05), and the DLP group (2.92 ± 0.91 μm) had no significant difference (P > .05). For trueness, the RMSE was greater in the PJP (34.90 ± 4.91 μm) and SLA (19.01 ± 0.95 μm) groups than in the gypsum (16.47 ± 0.47 μm) group (P < .05), and no significant difference was found between the DLP (17.10 Å} 1.77 μm) and gypsum groups. Regarding precision, the RMSE ranking was gypsum = DLP = SLA < PJP group. The RMSE ranges in the gypsum, DLP, PJP, and SLA groups at different times were 6.79 to 8.86 μm, 5.44 to 10.17 μm, 10.16 to 11.28 μm, and 10.94 to 32.74 μm, respectively.

Conclusion: Although gypsum and printed preparation dies showed statistically significant differences in surface characteristics, accuracy, and dimensional stability, all tooth preparation dies were clinically tolerated and used to produce fixed restorations.

Purpose: To evaluate the circumferential bone level and the morphological changes in posterior mandibular ridge of mandibular overdenture wearers submitted to conventional and immediate loading through cone beam computed tomography (CBCT) at 1 and 3 years.

Material and methods: Twenty participants who received 2 NDI (Facility - 2.9x10 mm) were randomly allocated to the conventional loading (CL: n=10) or immediate loading (IL: n=10) groups. CBCT scans were performed in each group to analyze the vertical (VBL) and horizontal (HBL) bone level around the implants, analyzed together with the posterior bone remodeling of the mandible measured at distances of 5, 10, 15, and 20 mm from the mental foramen (L1-L4). Differences between groups were verified using the student t test at a significance level of 5%.

Results: The IL group showed a significantly higher HBL in the first year (P=.028) and a significantly higher VBL in the third year (P=.032), with HBL of -0.22 mm and VBL of -0.59 mm, respectively. After the third year, measurements of the percentage of cortical and medullar height indicated that the IL group presented a significantly higher percentage of cortical bone height (40.1 ± 9.3) compared to the CL group (31.8 ± 5.8) at position L1 (P=.05). No difference was found for posterior ridge remodeling (P>.05).

Conclusions: IL group showed slightly higher values of HBL and VBL, and locally displayed more replacement of medullary by cortical bone. However, circumferential bone level values in the IL group are still clinically acceptable and the posterior resorption rate remained stable after 3 years of function, irrespective of the loading type.

Purpose: Several procedures are performed to achieve optimal esthetic results in single-tooth implants. However, there is discordance regarding the potential benefit and risks of immediate implant loading/provisionalization. The aim of this prospective case series is to investigate the effect of immediate provisionalization of single-tooth implants at healed sites for periimplant soft-tissue conditions, focusing on papilla formation around single implants.

Materials and methods: Twelve patients received a total of 12 implants in the incisor, canine or premolar region of the upper and lower jaw at healed sites with immediate chair-side provisionalization. Four months later, the temporary crown was replaced by the permanent crown. After 40±13.1 months, clinical follow-up was conducted, assessing Probing pocket depth (PPD); Bleeding on Probing(BoP); Mucosal recession (MR) and Width of Keratinized Mucosa (KM). Papilla index (PI) was determined immediately after implant placement (baseline), before removing the temporary crown (t1), 4 weeks after insertion of the definitive crown (t2) and at the final follow-up examination (t3) to evaluate papilla formation and its change over time.

Results: None of the implants were lost. The mean PPD was 2.5±0.39 mm, BoP of 25% and 3.5 mm of KM were observed at the final follow-up. No implants showed MR. PI increased in all patients from 1.5±0.45 at baseline to 2.4±0.56 at t1, 2.6±0.47 at t2 and 3.02.6±0 at t3. The increase in PI between t0 and each individual timepoint from t1-t3 showed statistical significance.

Conclusion: The present results indicate the suitability and benefit of immediate provisionalization to achieve favorable peri-implant soft-tissue conditions and papilla formation.

Purpose: To evaluate the effect of material thickness and coffee thermocycling on the optical properties of definitive resin-based materials created via additive manufacturing (AM) and subtractive manufacturing (SM).

Materials and methods: Specimens were prepared in three thicknesses (1, 1.5, and 2 mm) from three AM (3D-CB, 3D-TH, and 3D-CT) and two SM (G-CAM and VE) resin-based materials (n = 15 per material and thickness combination). Color coordinates of each specimen were measured after polishing and after 10,000 cycles of coffee thermocycling. Color differences (ΔE00s) and relative translucency parameter (RTP) values were calculated. After logarithmic transformation, ΔE00 values were analyzed with two-way ANOVA, while RTP values were analyzed with generalized linear model test (α = .05).

Results: 3D-TH had the highest pooled ΔE00 and G-CAM had the lowest (P ≤ .004). 3D-CB had higher pooled ΔE00 than VE and 3D-CT (P ≤ .002). For the SM group, the 1.5-mm and 2-mm 3DCT specimens and 1-mm 3D-TH specimens had lower ΔE00 than 1.5-mm and 2-mm 3D-TH specimens (P ≤ .036). Most of the AM specimens and 1-mm VE specimens had higher ΔE00 than 2-mm G-CAM specimens (P ≤ .029). Further, most AM specimens had higher ΔE00 than 1.5-mm G-CAM specimens (P ≤ .006). RTP values increased in order of 3D-CT, G-CAM, VE, 3D-CB, and 3D-TH specimens (P < .001). Increased thickness and coffee thermocycling mostly reduced RTP (P < .001).

Conclusions: 3D-TH typically had higher color change values than SM specimens, while G-CAM typically had lower color change values than AM specimens. Only the 1.5-mm and 2-mm 3D-TH specimens had unacceptable color changes. Thickness and coffee thermocycling mostly reduced the translucency.

Purpose: To evaluate the effectiveness and accuracy of a proposed duplication technique in terms of one- and three-dimensional discrepancies between an original abutment and polyurethane duplicates obtained through a conventional workflow in single-implant rehabilitation.

Materials and methods: A titanium, shoulderless abutment was chosen for a single-implant cemented rehabilitation. The master cast was made using a plastic-based die system, and the implant portion was separated. The implant section was consecutively duplicated eight times using a manual technique with polyvinyl siloxane and unfilled polyurethane resin as impression and die materials. The duplicates were analyzed with a coordinate-measuring machine (SmartScope Flash 200, Optical Gaging Products): one- and three- dimensional discrepancies were determined for each duplicate on 20 analysis points (A to T) located on the abutment surface. Changes in the abutment radius were also calculated to estimate the effects on cement thicknesses.

Results: One-dimensional discrepancies were -0.5 Å} 61.2 μm, -6.6 Å} 39.7 μm, and -19.4 Å} 47.8 μm on the X, Y, and Z axes, respectively; three-dimensional variation was -66.4 Å} 60.1 μm. Friedman test showed no significant difference between duplicates' one-dimensional variations on X (P = .059), Y (P = .156), or Z (P = .223) axes; a significant difference was found regarding three-dimensional changes (P < .001). Dunn test showed higher discrepancies on the X axis and on the abutment head. Mean variation of the abutment radius was -12.09 μm.

Conclusions: The abutment duplication technique was shown to be an accurate and repeatable procedure for single cementable restorations.

Purpose: To examine the influence of abutment emergence angle and abutment height on marginal peri-implant bone stability in patients not considered susceptible to peri-implantitis. Furthermore, it was analyzed whether titanium-base (Ti-base) abutments lead to wider abutment emergence angles compared to one-piece abutments.

Materials and methods: A total of 48 abutments (ie, 24 Ti-base and 24 one-piece abutments in 24 patients) were evaluated at abutment installation, after 1 year, and thereafter on a yearly basis for up to 5 years. Clinical and radiographic outcome variables were assessed.

Results: With regard to peri-implant marginal bone stability, only moderately negative, albeit significant, correlations were found on the mesial sides of the one-piece abutments after 4 and 5 years for an abutment emergence angle > 30 degrees. No statistically significant negative correlations were found for distances of ≤ 1.5 mm between the restoration margin and the crestal peri-implant bone level for either Ti-base or for one-piece abutments. Furthermore, abutments bonded to Ti-bases were not associated with larger emergence angles than one-piece abutments.

Conclusions: For patients at low risk of developing peri-implantitis, it can be concluded that neither a larger abutment emergence angle (> 30 degrees) nor a distance of ≤ 1.5 mm between the restoration margin and the crestal peri-implant bone level are associated with marginal peri-implant bone loss. Furthermore, abutments bonded to Ti-bases are not associated with wider emergence angles than one-piece abutments.

Purpose: To evaluate relevant material properties (flexural strength [σf], elastic modulus [E], water sorption [Wsp] and solubility [Wsl], and biocompatibility) of an additive manufacturing (AM) polymer vs a heat-curing acrylic resin (AR; control) for the manufacture of complete dentures, testing the hypothesis that fabrications from both materials would present acceptable material properties for clinical use.

Materials and methods: The σf, E, Wsp, and Wsl were evaluated according to the ISO 20795-1:2013 standard, and the biocompatibility was evaluated using MTT and SRB assays. Disk-shaped specimens were fabricated and used for Wsp (n = 5), Wsl (n = 5), and biocompatibility (n = 3) testing. For assessment of σf and E, bar-shaped specimens (n = 30) were fabricated and stored in 37°C distilled water for 48 hours or 6 months before flexural testing in a universal testing machine with a constant displacement rate (5 ± 1 mm/minute). Data from σf, E, Wsp, Wsl, and biocompatibility tests were statistically analyzed using Student t test (α = .05). Weibull analysis was also used for σf and E data.

Results: Significant differences between the two materials were found for the evaluated material properties. Water storage for 6 months did not affect the flexural strength of the AM polymer, but this material showed inadequate σf and Wsl values.

Conclusions: Despite adequate biocompatibility and strength stability after 6 months of water storage, the AM polymer recommended for complete dentures needs further development to improve the material properties evaluated in this study.

Purpose: The aim of this scoping review is to categorize 3D-printing applications of polymeric materials into those where there is evidence to support their clinical application and to list the clinical applications that require a greater evidence base or further development before adoption.

Materials and methods: An electronic search on PubMed, EMBASE, Scopus (Elsevier), and Cochrane Library databases was conducted, including articles written in English and published between January 2003 and September 2023. The search terms were: ((3D printing) OR (3-dimensional printing) OR (three dimensional printing) OR (additive manufacturing)) AND ((polymer) OR (resin)) AND (dent*). Case reports, in vitro, in situ, ex vivo, or clinical trials focused on applications of 3D printing with polymers in dentistry were included. Review articles, systematic reviews, and articles comparing material properties without investigation on clinical application and performance/accuracy were excluded.

Results: The search provided 3,070 titles, and 969 were duplicates and removed. A total of 2,101 records were screened during the screening phase, and 1,628 records were excluded based on title/abstract. In the eligibility phase, of the 473 full-text articles assessed for eligibility, 254 articles were excluded. During the inclusion phase, a total of 219 studies were included in qualitative synthesis.

Conclusions: There is lack of clinical evidence for the use of 3D-printing technologies in dentistry. Current evidence, when investigating clinical outcomes only, would indicate non-inferiority of 3D-printed polymeric materials for applications including diagnostic models, temporary prostheses, custom trays, and positioning/surgical guides/stents.