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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.

Background: To evaluate changes in hard and soft tissue during the first 6 months after immediate implant placement and provisionalization (IIPP) of a single maxillary incisor.Methods: Failed maxillary incisors were replaced with IIP implants in 34 patients. Intraoral scans and cone beam computed tomography (CBCT) were performed before and 6 months after IIPP. Changes in soft tissue thickness, soft tissue contour, and hard tissue contour were measured by a three-dimensional superimposition method. The correlations of hard and soft tissue contour changes were assessed.Results: A total of 31 patients completed the study. Soft tissue contour tended to collapse after 6 months. Soft tissue was significantly thickened 1–3 mm below the gingival margin. Correlation analysis showed strong correlations between the hard and soft tissue contour changes at 0–5 mm apical to the implant platform. The mid-facial recession at 6 months was −0.46 ± 0.55 mm.Conclusions: Soft tissue contour collapsed after tooth extraction, regardless of IIPP. Both soft and hard tissue change affected the soft tissue contour change.

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.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.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 ΔEThe ΔEThe 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.

To assess the accuracy of intraoral digital impressions for gingival contour captured in the esthetic zone in vivo.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.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, p0.001; 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 (p0.05).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.Intraoral digital impressions could be a recommended method for recording 3-dimensional gingival contour in the esthetic zone.

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

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.

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

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.

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

The power generation characteristics of bifacial PV module on water surface are complicated. This paper proposed a water surface reflectivity model, which takes the light reflection characteristics on the calm water surface and the fluctuating water surface into consideration. The experimental data shows that the average absolute difference between actual water surface reflectivity and simulation data is 0.88%. A power generation model of the bifacial PV module was proposed on the basis of considering of the background reflectivity and the feature of bifacial PV module. The experimental data shows that the average absolute difference between actual PV power generation and simulation data is 2.1%. An approximate power generation enhancement ratio was proposed to estimate the power generation of bifacial PV module. Experimental results show that the average absolute difference between the approximate data and the actual data is 0.7%.