Quantitative analysis of the color in six CAD-CAM dental materials of varied thickness and surface roughness: An in vitro study.

STATEMENT OF PROBLEM: Computer-aided design and computer-aided manufacturing (CAD-CAM) monochromatic restorative materials are gaining popularity because of their convenience and efficiency. However, studies that quantitatively analyzed color change associated with thickness and surface roughness are sparse. PURPOSE: The purpose of this in vitro study was to quantitatively evaluate the color of 6 CAD-CAM monochromatic materials of different thickness and surface roughness using the CIELab color system. MATERIAL AND METHODS: A total of 150 12×12-mm square specimens of 6 different CAD-CAM monochromatic materials (VITA Enamic HT [VE], IPS e.max CAD HT [LS], LAVA Ultimate HT [LU], Telio CAD HT [TE], VITA Suprinity HT [VS], and Celtra Duo HT [CD]) in shade A2 and 5 different thicknesses (from 0.5 mm to 2.5 mm, with 0.5-mm increments) were fabricated (n=5). After 3 different surface treatments (polished, roughened by SiC P800-grit, and P300-grit), CIELab color parameters (L*, a* and b*) were measured using a spectrophotometer (VITA Easyshade V), and surface roughness was measured with a profilometer (VK-X200). Color variation was quantified by ΔE00 and 50:50% acceptability and perceptibly thresholds. Data analyses were performed using MANOVA, 2-way ANOVA, post hoc Tukey-Kramer test, and the 1-sample t test (α=.05). RESULTS: The L*, a*, and b* of the monochromatic specimens were significantly influenced by material type, thickness, and surface roughness (P<.001). An overall increase in the L* (from 61.90 to 82.2), a* (from -4.22 to 1.16), and b* (from 5.48 to 43.22) of the specimens was observed with increased thickness. The roughened specimens exhibited lower L* and higher a* and b* than the polished ones (P<.001). The use of P300-grit for roughening resulted in greater ΔE00 compared with P800-grit (P<.001). As thickness decreased or surface roughness increased, the ΔE00 increased and exceeded the acceptability and perceptibly thresholds for color difference. CONCLUSIONS: Material type, thickness, and surface roughness were major factors affecting the color of CAD-CAM monochromatic materials. Variations in thickness of 0.5 mm or more, as well as roughening treatments, may lead to clinically unacceptable color changes.

Effects of thickness and polishing treatment on the translucency and opalescence of six dental CAD-CAM monolithic restorative materials: an in vitro study.

BACKGROUND: Computer-aided design and computer-aided manufacturing (CAD-CAM) materials for prosthetic is gaining popularity in dentistry. However, limited information exists regarding the impact of thickness and roughening treatment on the optical properties of contemporary CAD-CAM restorative materials. This study aimed to quantitatively evaluate the translucency and opalescence of six dental CAD-CAM materials in response to different thicknesses and roughening treatments. METHODS: Six dental CAD-CAM materials, lithium disilicate glass-ceramic (IPS e.max CAD, LS), polymer-infiltrated ceramic (VITA Enamic, VE), resin-nano ceramic glass-ceramic (LAVA Ultimate, LU), polymethyl methacrylate (Telio CAD, TE), and two zirconia reinforced lithium silicate (VITA Suprinity, VS, and Celtra Duo, CD), in shade A2 were prepared as 12 × 12mm2 specimens of four thicknesses (0.5mm, 1.0mm, 1.5mm, and 2.0mm) (N = 240, n = 10). After three different treatments (polished, roughened by SiC P800-grit, and SiC P300-grit), the translucency parameter (TP00) and opalescence parameter (OP) were measured with a spectrophotometer (VITA Easyshade V). The surface roughness was analyzed with a shape measurement laser microscope. The data were analyzed using a MANOVA, post hoc Tukey-Kramer test, the t test, and regression analysis (α = .05). RESULTS: The TP00 and OP were significantly influenced by material type, thickness and roughening treatment (P < .05). TP00 showed a continues decline with increasing thicknesses, while the variations of OP were material-dependent. TP00 ranged from 37.80 (LS in 0.5mm) to 5.66 (VS in 2.0mm), and OP ranged from 5.66 (LU in 0.5mm) to 9.55 (VS in 0.5mm). The variations in TP00 of all materials between adjacent thicknesses ranged from 2.10 to 15.29, exceeding the acceptable translucency threshold except for LU. Quadratic and logarithmic regression curves exhibited the best fit for TP00 among the materials. Compared to polished specimens, rougher specimens exhibited lower TP00 and higher OP in all materials except for LS (P < 0.05). Roughening with P300-grit decreased TP00 and OP by an average of 2.59 and 0.43 for 0.5mm specimens, and 1.26 and 0.25 for 2.0mm specimens, respectively. CONCLUSIONS: Variations in translucency caused by thickness and roughening treatment were perceptible and may be clinically unacceptable. Careful consideration should be given to the selection of CAD-CAM materials based on their distinct optical properties.

Clinical evaluation and quantitative occlusal change analysis of posterior implant-supported all-ceramic crowns: A 3-year randomized controlled clinical trial.

OBJECTIVES: To compare the survival and complication rates of posterior screw-retained monolithic lithium disilicate (LS2 )/veneered zirconia (ZrO2 ) single implant crowns (SICs), as well as analyze the occlusal changes observed during a 3-year follow-up period. MATERIALS AND METHODS: Thirty-three patients were included and randomly divided into two groups. The test group consisted of 17 patients who received monolithic-LS2 -SIC, while the control group consisted of 16 patients who received veneered-ZrO2 -SIC. Implant/prosthesis survival rates, technical complications, peri-implant soft tissue conditions, and quantitative occlusal changes of SIC (obtained by the intra-oral scanner and analyzed in reverse software Geomagic Control 2015) were assessed at 1- and 3-year follow-ups. Bone loss and Functional Implant Prosthodontic Score (FIPS) were evaluated at a 3-year follow-up. RESULTS: After a 3-year follow-up period, one patient dropped out of the follow-up. No implant loss was observed. One crown was fractured, resulting in prosthesis survival rates of 93.75% for the monolithic group and 100% for the veneered group. A technical complication rate of 25% (4/16) was observed in the veneered group (p = .333). No significant differences in the marginal bone loss were observed at the 3-year follow-up (0.00 (-0.22, 0.17) mm versus 0.00 (-0.12, 0.12) mm, p = .956). The total FIPS scores for the test group were 9.0 (9.0, 9.0), while the control group received scores of 9.0 (8.0, 10.0) (p = .953). The changes in mean occlusal clearance were 0.022 ± 0.083 mm for the test and 0.034 ± 0.077 mm for the control group (at 3 years, p = .497). The changes in occlusal contact area were 1.075 ± 2.575 mm2 for the test and 1.676 ± 2.551 mm2 for the control group (at 3 years, p = .873). CONCLUSION: After a 3-year follow-up, screw-retained monolithic LS2 and veneered ZrO2 SIC demonstrated similar survival rates. The occlusal performance of implant prostheses needs to be closely examined during follow-up, and appropriate occlusal adjustments need to be considered.

Clinical Effect of Free Gingival Grafts on the Increase in Keratinized Mucosa Width at the Buccal Aspect of Implants in Adjacent Mandibular Molars: A Retrospective Study.

The aim of this retrospective study was to evaluate the effect of free gingival grafts (FGGs) at adjacent mandibular molar implants and to compare the clinical outcomes between the first molar (M1) and second molar (M2) sites. Twenty-one patients with 44 implants were included. At the 3-year follow-up, the mean increase in the keratinized mucosa width (KMW) was 2.35 ± 1.33 mm, and the mean KMW shrinkage rate was 58% ± 23%. M1 sites showed a significantly greater increase of KMW and less graft shrinkage than M2 sites (M1: 2.87 ± 1.40 mm and 49% ± 24%, M2: 1.83 ± 1.06 mm and 66% ± 19%, P < .05). The results show that using FGG to increase KMW in mandibular molar implants was a predictable treatment method, and M1 sites were associated with a greater KMW increase than M2 sites.

Quantitative analysis of color accuracy and bias in 4 dental CAD-CAM monolithic restorative materials with different thicknesses: An in vitro study.

STATEMENT OF PROBLEM: Computer-aided design and computer-aided manufacturing (CAD-CAM) monolithic restorative materials have become a popular option because of advantages such as convenience and efficiency. However, studies that quantitatively analyzed their color accuracy and bias are lacking. PURPOSE: The purpose of this in vitro study was to evaluate the color accuracy and bias of 4 CAD-CAM monolithic restorative materials with different thicknesses by using the CIELab color space. MATERIAL AND METHODS: Four types of dental CAD-CAM monolithic restorative materials in shade A2, lithium disilicate glass-ceramic (IPS e.max CAD), infiltrated ceramic (VITA Enamic), resin-nano ceramic (LAVA Ultimate), and polymethyl methacrylate (Telio CAD), were prepared as 12×12-mm specimens of 10 different thicknesses (from 0.5 to 5.0 mm) (N=200, n=5). After polishing with SiC P1500-grit, CIELab color coordinate parameters of the specimens were measured with a spectrophotometer (VITA Easyshade V). The color accuracy and bias were described by ΔE00, ΔL∗, Δa∗, and Δb∗ in the CIELab color space, and the data were analyzed by using a 2-way ANOVA, post hoc Tukey-Kramer test, and the t test (α=.05). RESULTS: The ΔE00, ΔL∗, Δa∗, and Δb∗ were significantly influenced by material type and thickness (P<.001). Specimens at a thickness of 0.5 mm represented the maximum ΔE00. The minimum ΔE00 was observed at a thickness of 2.0 mm for LAVA Ultimate, 1.5 mm for VITA Enamic and Telio CAD, and 4.0 mm for IPS e.max CAD. The ΔE00 of all specimens significantly exceeded the 50:50% acceptability threshold (1.8 unit) (P<.001). LU exhibited higher ΔE00, Δa∗, and Δb∗ than the other 3 materials in all thickness expect for 0.5 mm. For color bias, the ΔE00 was more influenced by Δb∗ and ΔL∗ than Δa∗. CONCLUSIONS: The color accuracy and bias were significantly affected by material type and thickness. The color inaccuracy of the tested materials was statistically significant and clinically perceptible. Improved clinical outcomes may be expected from the 1.5-mm- to 2.0-mm-thick restorations.

Patient-reported outcome measures and clinical outcomes following peri-implant vestibuloplasty with a free gingival graft versus xenogeneic collagen matrix: a comparative prospective clinical study.

BACKGROUND: The objective of this study was to compare patient-reported outcome measures (PROMs) and clinical outcomes after augmentation with xenogeneic collagen matrix (XCM) or free gingival graft (FGG) during different postoperative phases. METHODS: Forty-two patients (21 per group) with keratinized mucosa width (KMW) of < 2 mm at buccal implant sites in the posterior mandible were enrolled. All underwent vestibuloplasty and were allocated to either FGG (control) or XCM (test) group. Intraoperative morbidity of pain, stress, nausea, tolerance to time, and acceptance of surgery were evaluated immediately after surgery. The severity and duration of subjective pain, swelling, and bleeding were compared within a 2-week postoperative period. The willingness to retreat and satisfaction were assessed at 6 months. All PROMs were obtained using questionnaires and visual analog scales. The buccal KMW and other peri-implant parameters were also evaluated. RESULTS: No significant between-group differences were observed in PROMs immediately after surgery, except acceptance of surgery (0, 0-30.0 vs. 30, 0-50.0, p = 0.025). At 2 weeks, pain severity (46.7 ± 25.9 vs 61.9 ± 20.2, p = 0.040) and duration (5.52 ± 3.57 vs 8.48 ± 2.80, p = 0.005) were significantly lower in the test group, and pain perception during speaking and chewing was significantly higher for FGG, with no significant between-group differences in swelling and bleeding. At 6 months, the test group showed a higher willingness to retreat (76% vs 43%, p = 0.021); however, satisfaction with treatment outcomes was similar in both groups. At 6 months, the gain of KMW was significantly higher in FGG than in XCM (XCM: 1.57 ± 1.69 mm, FGG: 2.68 ± 1.80 mm, p = 0.003). Other peri-implant parameters did not show significant differences. CONCLUSIONS: Within the limitation of the present nonrandomized study, XCM demonstrated more positive PROMs than FGG during different postoperative phases, mainly for less pain perception during the early healing stage, but was inferior to FGG in terms of gain of KMW. For KMW augmentation in the posterior mandible, XCM may be indicated when patients can bear little pain. CLINICAL TRIAL REGISTRATION: ChiCTR1900022575 , date of registration: 17/4/2019, retrospectively registered.

Effects of printing layer thickness on mechanical properties of 3D-printed custom trays.

STATEMENT OF PROBLEM: The layer thickness serves as a straightforward and controllable parameter to alter the mechanical properties of 3D-printed custom trays. However, how the printing layer thickness affects the mechanical properties of the trays is not fully understood. PURPOSE: The purpose of this in vitro study was to investigate the effects and their underlying mechanisms and to optimize the mechanical properties through modulation of the printing layer thickness. MATERIAL AND METHODS: Polylactic acid (PLA) specimens were 3D-printed with 5 layer thicknesses from 0.1 mm to 0.5 mm. The bond, flexural, and tensile strengths were measured by using a universal test machine. Postfracture interfaces were examined by means of scanning electron microscopy. Additionally, the printing dimensional accuracy was estimated by measuring the size deviations between the printed and virtual specimens, and the printing times were recorded. RESULTS: With increasing PLA printing layer thickness, the tensile bond strength first increased and then decreased, peaking at a thickness of 0.4 mm. While the flexural and tensile strengths decreased, the printing dimensional accuracy remained constant from 0.1 mm to 0.4 mm and then decreased at 0.5 mm. The printing time sharply decreased as printing layer thickness increased. CONCLUSIONS: Moderate layer thickness provided the best properties for 3D-printed custom trays.

Clinical and radiographic outcomes of reentry lateral sinus floor elevation after a complete membrane perforation.

BACKGROUND: Although small perforation of the maxillary sinus schneiderian membrane is a well-documented complication during lateral sinus floor elevation (LSFE), complete perforations larger than 10 mm often result in discontinuation of surgery. Reports on reentry LSFE and its long-term outcomes are sparse. PURPOSE: To evaluate the long-term outcomes of reentry LSFE following complete membrane perforation to elucidate the technical details of the reentry procedure. MATERIALS AND METHODS: We assessed the medical records of all patients receiving LSFE from 2008 to 2017 in the Department of Oral Implantology, Peking University Hospital of Stomatology. Twenty-two patients receiving reentry LSFE after complete membrane perforation were enrolled. Data were recorded using cone beam computer tomography: including the residual bone height, membrane thickness of the sinus prior to surgery (MT1 ), and before reentry (MT2 ), and height of the bone graft during the reentry procedure (HBG). Cumulative survival rate of implants (CSR), marginal bone loss (MBL), and subsequent complications were also recorded. RESULTS: From 2008 to 2017, 2023 consecutive patients (2262 sinuses) who underwent LSFE were screened. Complete membrane perforation occurred in 28 patients and resulted in discontinuation of surgery (1.2%). Twenty two patients were enrolled and received reentry LSFE within 3-6 months. Two patients undergoing the reentry procedure were suspended due to excessive membrane perforation, while the other 20 finished reentry sinus bone graft. In the reentry procedure, the HBG was 9.73 ± 2.67 mm with 34 implant placements. The MT1 and MT2 were 1.03 ± 0.43 and 1.91 ± 1.45 mm, respectively, showing a statistically significant difference (P < .05). After a follow-up of 2-10 years, CSR was 97.1%, and MBL was 0.64 ± 0.50 mm. CONCLUSIONS: The long-term outcome of reentry LSFE is predictable and reentry LSFE offers a reliable alternative following complete membrane perforation. However, the procedure is relatively sensitive and should be performed by experienced surgeons.

Evaluation of intraoral digital impressions for obtaining gingival contour in the esthetic zone: accuracy outcomes.

OBJECTIVES: To assess the accuracy of intraoral digital impressions for gingival contour captured in the esthetic zone in vivo. MATERIAL AND METHODS: Five participants with full upper dentition were recruited. For each participant, three scans were taken using two intraoral scanning (IOS) systems (3Shape TRIOS Color, TRC; CEREC Omnicam, OC) respectively; three conventional impressions (CIs) were taken using vinyl polysiloxane materials. The CIs of all participants were casted and then digitized with a model scanner (IScan D103i, Imetric). Precision was evaluated by superimposing three repeated STL datasets per participant within each group and calculating the (90th-10th)percentile/2 values. The CIs were the reference for evaluating the level of system error of the two IOS systems from the true value. Digital models from CI and each IOS group were superimposed and (mean positive deviation-mean negative deviation)/2[mean negative deviation, mean positive deviation] were calculated to assess trueness level of the two IOS systems. RESULTS: For the soft tissue acquisition, precision results of each group were 45.10 ± 12.54 µm in TRC, 66.04 ± 13.46 µm in OC, and 63.66 ± 17.19 in CI (TRC vs OC, p < 0.001; TRC vs CI, p = 0.001; OC vs CI, p = 0.66). Trueness results were 80.12 ± 8.69[- 112.10 ± 9.88, 48.13 ± 13.79] µm in TRC and 82.70 ± 8.85[- 121.41 ± 15.40, 43.98 ± 11.86] µm (p > 0.05). CONCLUSIONS: In dentate situations, the two tested IOS systems achieved a clinically satisfying accuracy for capturing gingival contour in anterior maxilla, with a comparable or superior precision to the CI. TRC achieved a similar trueness and a higher precision level compared with OC. CLINICAL RELEVANCE: Intraoral digital impressions could be a recommended method for recording 3-dimensional gingival contour in the esthetic zone.

Quantitative clinical adjustment analysis of posterior single implant crown in a chairside digital workflow: A randomized controlled trial.

OBJECTIVES: To compare the three-dimensional changes in quantity and morphology following clinical adjustment of a posterior single implant crown between chairside digital workflow (test) and hybrid digital workflow (control). MATERIALS AND METHODS: A total of 33 participants were included for single-tooth replacement with screw-retained crowns in posterior sites of either the maxillary or mandible. A total of 17 participants were carried to a chairside digital workflow, receiving monolithic lithium disilicate (LS2)-crowns (test), while the remaining 16 participants were fitted with CAD/CAM-fabricated zirconia superstructures and hand-layered ceramic veneering crowns (control). As each crown underwent intraoral scanning (3Shape TRIOS Color, 3Shape), 3D digital models were rendered. These scans were taken both before and after try-in. Clinical adjustment dimensional changes were measured by superimposing the optical scans of models within a reverse software (Geomagic Control 2014). Adjustment counts and amounts (from vertical dimension) between two workflows were assessed and compared. Time consumption was recorded for efficiency analysis. RESULTS: All patients were successfully treated in both groups. The median maximum vertical adjustment (taking both occlusal and interproximal surfaces into consideration) was 237 µm ± 112 in the test group and 485 µm ± 195 in the control group (p < .0001), respectively. The median adjustment count was 2.00 ± 1.09 in test group and 3.00 ± 1.05 in control group (p = .001), respectively. The total active working time/ total time for two workflows was 92.3/113.7 min for the test group and 146.3/676.3 min for the control group, respectively. CONCLUSION: The test group showed fewer adjustments and apparent precision on the occlusal surface compared with the control group with only a fifth of the consumption of a hybrid workflow.

Accuracy of multi-implant impressions using 3D-printing custom trays and splinting versus conventional techniques for complete arches.

PURPOSE: To assess the three-dimensional (3D) accuracy of multi-implant impressions for complete arches obtained using 3D printing technology, and to determine the clinical feasibility of this approach by comparing the results obtained with those obtained with conventional impression techniques. MATERIALS AND METHODS: A maxillary model matrix with four implant analogs was used to fabricate 10 stone reference models (control) to simulate edentulous patients. Ten 3D-printed impressions were made using polylactic acid custom open trays with component splinting (3D-printed group). To make 10 conventional impressions of the reference models, the poly(methyl methacrylate) open trays with splinting technique was used (conventional group). Impressions were poured with a type IV dental stone, which had been digitalized utilizing a high-resolution laboratory scanner after connecting the polymer scan bodies. Standard tessellation language (STL) datasets from the two groups of stone models were superimposed with the corresponding reference models. The interimplant distances and interimplant angulations for each implant pair were measured for the reference models and for the two test groups' definitive models, to assess 3D deviations. In addition, the mechanical properties of polylactic acid and poly(methyl methacrylate) tray materials were compared by means of three-point loading and tensile bond tests. The Student t test was used to compare the differences in implant position and mechanical properties between the two groups, while implant angulations were analyzed with Wilcoxon's rank-sum test, at P = .05. RESULTS: There was less implant-position deviation for the 3D-printed group (mean ± SD: 56.37 ± 12.52 µm) than for the conventional group (71.94 ± 18.86 µm) (P = .014). No significant differences were found in angular deviation between the two groups (P > .05). Flexural strength results suggested that polylactic acid (112.7 ± 1.62 MPa) was stronger than poly(methyl methacrylate) (104.0 ± 2.17 MPa; P < .0001). The tensile bond strength of polylactic acid (0.07 ± 0.005 MPa) was higher than that of poly(methyl methacrylate) (0.03 ± 0.004 MPa; P < .0001). CONCLUSION: The 3D-printing multi-implant impression technique could be an alternative to conventional impression techniques for complete arches.

Labial soft tissue contour dynamics following immediate implants and immediate provisionalization of single maxillary incisors: A 1-year prospective study.

BACKGROUND: Soft tissue dynamics in the esthetic zone are gaining increasing attention in recent years. Emerging intraoral scanning technology allows easier capture of soft tissue contours. PURPOSE: To quantitatively assess the time-dependent contour alterations of labial soft tissue following single immediate implants and immediate provisionalization (IIPP) in maxillary incisors via intraoral scanning. MATERIALS AND METHODS: This was a prospective cohort study. Thirty eligible consecutive patients were included and received immediate replacement of a failure maxillary single incisor. A screw-retained immediate restoration was delivered for each patient. Subsequently, the anterior maxillary region was scanned by an intraoral scanning system at four time points: preoperation (baseline, BL), 3 months (3 m), 6 months (6 m), and 12 months (12 m). The Standard Tessellation Language files were exported to a dedicated software and superimposed for visual analysis. At 3, 6, and 12 months, the mid-facial mucosa level (ML) was assessed, and the precise three-dimensional (3D) configuration of the altered volume was calculated and reconstructed for visual analysis. Furthermore, quantitative analysis of the reconstructed morphology was performed using the following parameters: mean change in thickness (△d), mesio-distal width (w), coronal-apical height (h), and horizontal and vertical position of the thickest point represented by coordinates (x, z). RESULT: Twenty-seven of thirty enrolled patients were finally available for analysis at the 1-year follow-up. In general, the frontal view of the reconstructed volume exhibited a crescent shape. The mid-facial ML change at 3, 6, and 12 months was -0.05 ± 0.36 mm, -0.03 ± 0.32 mm, and -0.24 ± 0.37 mm, respectively (P = .012). The mean change in thickness at 3 months (△d3m ), 6 months (△d6m ), and 12 months (△d12m ) was 0.50 ± 0.19 mm, 0.59 ± 0.21 mm, and 0.62 ± 0.22 mm, respectively (P <.001). At 12 months, nine patients had a △d less than 0.5 mm. The mean △d3 m /△d12 m and △d6 m /△d12 m was 0.81 ± 0.17 and 0.96 ± 0.13. The w, h, x, and z results showed no significant differences during the 1-year observation (P = .126, P = .324, P = .635, P = .263). At 12 months, w, h, x, and z were 11.57 ± 1.77 mm, 6.46 ± 2.01 mm, 0.03 ± 1.43 mm, and 2.16 ± 0.65 mm, respectively. CONCLUSION: During the 1-year observation following single IIPP treatment in maxillary incisors, the labial soft tissue contour showed a continuous alteration resulting in a mean change in thickness of 0.62 mm that occurred mainly in the first 3 months and tended to be relatively stable after 6 months, while the crescent-like shape, width, height, and thickest point position of the alteration volume remained stable after 3 months. No advanced mid-facial recession was observed.