Improved positional accuracy of dental implant placement using a haptic and machine-vision-controlled collaborative surgery robot: A pilot randomized controlled trial.

AIM: To compare the implant accuracy, safety and morbidity between robot-assisted and freehand dental implant placement. MATERIALS AND METHODS: Subjects requiring single-site dental implant placement were recruited. Patients were randomly allocated to freehand implant placement and robot-assisted implant placement. Differences in positional accuracy of the implant, surgical morbidity and complications were assessed. The significance of intergroup differences was tested with an intention-to-treat analysis and a per-protocol (PP) analysis (excluding one patient due to calibration error). RESULTS: Twenty patients (with a median age of 37, 13 female) were included. One subject assigned to the robotic arm was excluded from the PP analysis because of a large calibration error due to the dislodgement of the index. For robot-assisted and freehand implant placement, with the PP analysis, the median (25th-75th percentile) platform global deviation, apex global deviation and angular deviation were 1.23 (0.9-1.4) mm/1.9 (1.2-2.3) mm (p = .03, the Mann-Whitney U-test), 1.40 (1.1-1.6) mm/2.1 (1.7-3.9) mm (p < .01) and 3.0 (0.9-6.0)°/6.7 (2.2-13.9)° (p = .08), respectively. Both methods showed limited damage to the alveolar ridge and had similar peri- and post-operative morbidity and safety. CONCLUSIONS: Robot-assisted implant placement enabled greater positional accuracy of the implant compared to freehand placement in this pilot trial. The robotic system should be further developed to simplify surgical procedures and improve accuracy and be validated in properly sized trials assessing the full spectrum of relevant outcomes.

Three-dimensional imaging analysis of CAD/CAM custom-milled versus prefabricated allogeneic block remodelling at 6 months and long-term follow-up of dental implants: A retrospective cohort study.

AIM: This retrospective cohort study aimed to volumetrically investigate the bone stability rate of prefabricated allogeneic bone blocks (PBB) and computer-aided design (CAD)/computer-aided manufacturing (CAM) custom-milled allogeneic bone blocks (CCBB) for ridge augmentation. MATERIALS AND METHODS: Nineteen patients were treated with 20 allografts: 11 CCBB, 9 PBB; 10 in the maxilla and 10 in the mandible. Clinical treatment history and cone beam computed tomography scans before surgery (t0), directly after graft surgery (t1) and after 6 months of healing prior to implant insertion (t2) were evaluated using a three-dimensional evaluation software for absolute bone volume, stability as well as vertical and horizontal bone gain. Furthermore, the inserted implants were analysed for survival, marginal bone loss (MBL) and complications for a mean follow-up period of 43.75 (±33.94) months. RESULTS: A mean absolute volume of 2228.1 mm3 (±1205) was grafted at t1. The bone stability rate was 87.6% (±9.9) for CCBB and 83.0% (±14.5) for PBB. The stability was higher in the maxilla (91.6%) than in the mandible (79.53%). Surgery time of PBB was longer than for CCBB (mean Δ = 52 min). The survival rate of the inserted implants was 100% with a mean MBL of 0.41 mm (±0.37). CONCLUSION: The clinical performance of both allograft block designs was equally satisfactory for vertical and horizontal bone grafting prior to implant placement. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov: NCT06027710.

Influence of sterilization on the retention forces of lithium disilicate and polymer-infiltrated ceramic-network crowns bonded to titanium base abutments: An in-vitro study.

OBJECTIVES: The aim of this study was to evaluate the effect of sterilization on the retention forces of lithium disilicate (LD) and polymer-infiltrated ceramic network (PICN) crowns bonded to titanium base (Ti-base) abutments. MATERIALS AND METHODS: Forty LD and 40 PICN crowns were milled and then bonded to 80 Ti-bases with two resin composite cements: Multilink Hybrid Abutment (mh) and Panavia V5 (pv) for a total of 8 groups (n = 10). Half of the specimens (test) underwent an autoclaving protocol (pressure 1.1 bar, 121°C, 20.5 min) and the other half not (control). Restorations were screw-retained to implants, and retention forces (N) were measured with a pull-off testing machine. The surfaces of the Ti-bases and the crowns were inspected for the analysis of the integrity of the marginal bonding interface and failure mode. Student's t-test, chi-square test, and univariate linear regression model were performed to analyze the data (α = 0.05). RESULTS: The mean pull-off retention forces ranged from 487.7 ± 73.4 N to 742.2 ± 150.3 N. Sterilized groups showed statistically significant overall higher maximum retention forces (p < .05), except for one combination (LD + mh). Sterilization led to an increased presence of marginal gaps and deformities compared to no-sterilization (p < .001), while no statistically significant relationship was found between failure mode and sterilization (p > .05). CONCLUSIONS: Sterilization may have a beneficial effect on the retention forces of LD and PICN crowns bonded to titanium base abutments, although it may negatively influence the integrity of the marginal bonding interface.

The impacts of registration-and-fixation device positioning on the performance of implant placement assisted by dynamic computer-aided surgery: A randomized controlled trial.

OBJECTIVES: To assess the efficacy of dynamic computer-aided surgery (dCAS) in replacing a single missing posterior tooth, we compare outcomes when using registration-and-fixation devices positioned anterior or posterior to the surgical site. Registration is performed on either the anterior or opposite posterior teeth. METHODS: Forty individuals needing posterior single-tooth implant placement were randomly assigned to anterior or posterior registration. Nine parameters were analyzed to detect the deviations between planned and actual implant placement, using Mann-Whitney and t-tests for nonnormally and normally distributed data, respectively. RESULTS: The overall average angular deviation for this study was 2.08 ± 1.12°, with the respective average 3D platform and apex deviations of 0.77 ± 0.32 mm and 0.88 ± 0.32 mm. Angular deviation values for individuals in the anterior and posterior registration groups were 1.58°(IQR: 0.98°-2.38°) and 2.25°(IQR: 1.46°-3.43°), respectively (p = .165), with 3D platform deviations of 0.81 ± 0.29 mm and 0.74 ± 0.36 mm (p = .464), as well as 3D apex deviations of 0.89 ± 0.32 mm and 0.88 ± 0.33 mm (p = .986). No significant variations in absolute buccolingual (platform, p = .659; apex, p = .063), apicocoronal (platform, p = .671; apex, p = .649), or mesiodistal (platform, p = .134; apex, p = .355) deviations were observed at either analyzed levels. CONCLUSIONS: Both anterior and posterior registration approaches facilitate accurate dCAS-mediated implant placement for single missing posterior teeth. The device's placement (posterior-to or anterior-to the surgical site) did not affect the clinician's ability to achieve the planned implant location.

A comparison of accuracy among different approaches of static-guided implant placement in patients treated with mandibular reconstruction: A retrospective study.

OBJECTIVE: This study aimed to evaluate the differences in the accuracy of immediate intraoral, immediate extraoral, and delayed dental implant placement with surgical guides (static computer-aided implant surgery) in patients treated with mandibular reconstruction. METHODS: This was a retrospective study. The patients were divided into three groups: immediate intraoral placement (IIO), immediate extraoral placement (IEO), and delayed placement (DEL). Four variables were used to compare the planned and actual implant positions: angular deviation, three-dimensional (3D) deviation at the entry point of the implant, 3D deviation at the apical point of the implant, and depth deviation. RESULTS: The angular deviation was significantly higher in the IIO group than in the IEO (p < .05) and DEL (p < .05) groups. The 3D deviation at the entry point was significantly higher in the IIO group than in the IEO (p < .05) and DEL (p < .01) groups. The 3D deviation at the apical point was significantly higher in the IIO group than in the IEO (p < .01) and DEL (p < .01) groups. The depth deviation was significantly higher in the IIO group than in the IEO (p < .05) and DEL (p < .05) groups. There was no statistical difference between the IEO and DEL group in angular and 3D deviation. CONCLUSION: With surgical guides, among the different approaches for implant placement, delayed implant placement remains the most accurate approach for patients treated with mandibular reconstruction.

Clinical evaluation of autonomous robotic-assisted full-arch implant surgery: A 1-year prospective clinical study.

OBJECTIVES: This prospective clinical study aimed to evaluate the accuracy and 1-year clinical follow-up performance of dental implant placement with an autonomous dental implant robot (ADIR) system in full-arch implant surgery. MATERIALS AND METHODS: Twelve patients with edentulous arches or final dentition received 102 implants using the ADIR system. Global platform deviation, global apex deviation, and global angular deviation between the planned and actual implants were calculated after surgery. Data were statistically analyzed for factors including jaws, implant positions, patient sequences, implant systems, and implant length. Surgery duration was recorded. Patients were followed for 3 months and 1 year after surgery. Periodontal parameters, buccal bone thickness (BBT), and facial vertical bone wall peak (IP-FC) were recorded. RESULTS: Among the 102 implants, the mean (SD) global platform deviation, global apex deviation, and global angular deviation were 0.53 (0.19) mm, 0.58 (0.17) mm, and 1.83 (0.82)°, respectively. The deviation differences between the mandible and maxilla did not show statistical significance (p > .05). No statistically significant differences were found for the jaws, implant positions, patient sequences, implant systems, and implant length to the deviations (p > .05). The periodontal parameters, the BBT, and IP-FC remained stable during 1-year follow-up. CONCLUSION: The ADIR system showed excellent positional accuracy. The 1-year follow-up after full-arch implant surgery indicated that the ADIR system could achieve promising clinical performance. Additional clinical evidence is requisite to furnish guidelines for the implementation of the ADIR system in full-arch implant surgery.

The influence of guide stabilizers and their application sequences on trueness and precision of surgical guides in free end situations: An in vitro analysis.

OBJECTIVES: To evaluate the impact of guide stabilizers and their application sequences on implant placement accuracy of guided implant surgery in multiple teeth loss at free end. MATERIALS AND METHODS: In this study, 96 implants were placed in the regions of #34, #36, and #37 of 32 identical mandibular models. The influence of using guide stabilizers or not (group A and group B) and various guide stabilizers application sequences (group B: #34 → #36 → #37; group C: #36 → #34 → #37; group D: #37 → #34 → #36) on implant placement trueness and precision was investigated. Data were analyzed using T-tests and one-way ANOVA. RESULTS: Group B showed significant benefits in enhancing implant placement precision. Compared to group A, it resulted in reducing 3D-deviation at crest and 2D deviation in vestibular-oral direction at both crest and apex. Furthermore, group D demonstrated greater improvement in global implant placement precision by reducing 2D deviation in mesial-distal direction at both crest and apex. Among the three different stabilizer application sequences, group D exhibited the highest level of implant placement precision. CONCLUSIONS: In cases of missing teeth at distal free end, the use of guide stabilizers and their application sequences does not have a significant impact on implant placement trueness. However, they do improve implant placement precision compared to methods that do not utilize guide stabilizers. Specifically, applying a guide stabilizer first at the furthest implant site to change teeth loss classification from free end to edentulous space with posterior support is the most reliable sequence.

Accuracy and patient-centered results of marker-based and marker-free registrations for dynamic computer-assisted implant surgery: A randomized controlled trial.

OBJECTIVES: To compare implant placement accuracy and patient-centered results between the dynamic computer-assisted implant surgeries (d-CAISs) using marker-based and marker-free registration methods. MATERIALS AND METHODS: A double-armed, single-blinded randomized controlled trial was conducted, in which 34 patients requiring single implant placement at the esthetic zone were randomly assigned to the marker-based (n = 17) or marker-free (n = 17) groups. The marker-based registration was performed using a splint containing radiopaque markers, while the marker-free registration used natural teeth. The primary outcome assessed implant positioning accuracy via angular and linear deviations between preoperative and postoperative implant positions in CBCT. Patients were also surveyed about the intraoperative experience and oral health impact profile (OHIP). RESULTS: The global linear deviations at the implant platform (0.82 ± 0.28 and 0.85 ± 0.41 mm) and apex (1.28 ± 0.34 and 0.85 (IQR: 0.64-1.50) mm) for the marker-based and marker-free groups respectively showed no significant difference. However, the angular deviation of the marker-free group (2.77 ± 0.92 ° ) was significantly lower than the marker-based group (4.28 ± 1.58 ° ). There was no significant difference in the mean postoperative OHIP scores between the two groups (p = .758), with scores of 2.74 ± 1.21 for marker-based and 2.93 ± 2.18 for marker-free groups, indicating mild oral health-related impairment in both. Notably, patients in the marker-free group showed significantly higher satisfaction (p = .031) with the treatment procedures. CONCLUSIONS: D-CAIS with a marker-free registration method for single implantation in the anterior maxilla has advantages in improving implant placement accuracy and patients' satisfaction, without generating a significant increase in clinical time and expenses.

Accuracy of implant placement via dynamic navigation and autonomous robotic computer-assisted implant surgery methods: A retrospective study.

OBJECTIVE: Optimal implant planning and placement allows the prosthesis to be well designed to achieve a satisfactory aesthetic and functional outcome. We aimed to compare deviations between implant planning and placement with the assistance of dynamic computer-assisted implant surgery (d-CAIS) or autonomous robotic computer-assisted implant surgery (r-CAIS) methods in a clinical setting. METHODS: The retrospective analysis of medical records between 2021 July and 2022 December was conducted to compare the implantation accuracy of the d-CAIS and r-CAIS system in partially edentulous patients through cone-beam computed tomography. Patient-reported outcomes (PROs) were recorded using a visual analogue scale (VAS). The Kolmogorov-Smirnov test was used to check the data distribution. Student's t-test or Mann-Whitney U-test was used as appropriate, with a defined significant difference (p < .05). RESULTS: Seventy-seven patients were analysed (124 implants), with 38 patients (62 implants) in the d-CAIS group and 39 patients (62 implants) in the r-CAIS group. The differences between d-CAIS and r-CAIS were 4.09 ± 1.79° versus 1.37 ± 0.92° (p < .001) in angular deviation; 1.25 ± 0.54 versus 0.68 ± 0.36 mm (p < .001) in coronal global deviation; 1.39 ± 0.52 versus 0.69 ± 0.36 mm (p < .001) in apical global deviation; the results of the PROMs showed no statistical difference between the two groups. CONCLUSIONS: r-CAIS allows more accurate implant placement than the d-CAIS technology. And both groups achieved overall satisfactory outcomes via VAS (Chinese Clinical Trial Registry ChiCTR2300072004).

Clinical accuracy of partially guided implant placement in edentulous patients: A computed tomography-based retrospective study.

OBJECTIVES: This retrospective study was intended to evaluate the clinical accuracy of partially guided template in guiding implant placement in edentulous patients. METHODS: A total of 120 implants were placed in 24 patients with at least one completely edentulous arch with a partially guided system. Based on CBCT data, a repeatable method was used to measure linear and angular deviations of implants at 3D level in Mimics medical software. The influence of supporting tissue and implant region on the accuracy was assessed, followed by the evaluation of direction of linear deviations in biologically vital areas. RESULTS: Linear deviations of all implants were 1.91 ± 0.68 mm, 1.47 ± 0.68 mm, and 1.02 ± 0.69 mm at apical, apical lateral, and apical vertical levels. When at the cervical, cervical lateral, and cervical vertical levels, the linear deviations were 1.53 ± 0.65 mm, 0.98 ± 0.53 mm, and 1.01 ± 0.69 mm, respectively. Angular deviation of all implants was 7.14 ± 3.41°. Implants guided by mucosa + tooth-supported templates showed higher linear deviations at apical vertical level (1.21 ± 0.72 mm vs. 0.86 ± 0.63 mm, p < .05) and cervical vertical level (1.18 ± 0.72 mm vs. 0.87 ± 0.63 mm, p < .05) than mucosa-supported templates, and implants in maxilla were found higher angular deviation than mandible (7.89 ± 3.61° vs. 6.29 ± 2.97°, p < .05). CONCLUSIONS: The partially guided template served as clinically viable surgical assistance in implant placement in edentulous patients. When using mucosa + tooth-supported template or placing implants in maxilla, more caution was required, especially in biologically vital areas.

Effect of implant shape and length on the accuracy of robot-assisted immediate implant surgery: An in vitro study.

OBJECTIVES: To compare the accuracy of immediate implant placement of cylindrical implants (CI) and tapered implants (TI) of different lengths using a robotic dental implant system. MATERIALS AND METHODS: CI and TI of three lengths (8, 10, and 12 mm) each were digitally planned and placed in a three-dimensional printed extraction socket model under robotic guidance. There were six groups with three samples in each group, resulting in a total of 18 samples. Implant angular deviation, platform point deviation (total, lateral, depth), and implant apical point deviation (total, lateral, depth) were recorded and compared between the different groups. RESULTS: The angular deviations for CI 8 mm, CI 10 mm, CI 12 mm, TI 8 mm, TI 10 mm, and TI 12 mm were 1.32° ± 0.19°, 1.03° ± 0.56°, 1.31° ± 0.38°, 1.27° ± 0.64°, 1.10° ± 0.43° and 1.05° ± 0.45°, respectively. The total deviations of platform and apical points for CI 8 mm, CI 10 mm, CI 12 mm, TI 8 mm, TI 10 mm, and TI 12 mm were 0.79 ± 0.18 mm, 0.77 ± 0.33 mm; 0.64 ± 0.21 mm, 0.55 ± 0.17 mm; 0.64 ± 0.37 mm, 0.65 ± 0.34 mm; 0.68 ± 0.26 mm, 0.71 ± 0.20 mm; 0.70 ± 0.12 mm, 0.66 ± 0.23 mm; and 0.71 ± 0.15 mm, 0.77 ± 0.29 mm, respectively, and had no significant differences. CONCLUSIONS: Within the limitation of this study, acceptable accuracy can be achieved for both TI and CI using robotic systems. Our study demonstrated that the implant shape and length did not affect the accuracy of immediate implant placement under robotic guidance in vitro. However, further trials are required to confirm their efficacy in clinical practice.

Accuracy of edentulous full-arch implant impression: An in vitro comparison between conventional impression, intraoral scan with and without splinting, and photogrammetry.

OBJECTIVES: The purpose of this in vitro study was to compare the trueness and precision of complete arch implant impressions using conventional impression, intraoral scanning with and without splinting, and stereophotogrammetry. MATERIALS AND METHODS: An edentulous model with six implants was used in this study. Four implant impression techniques were compared: the conventional impression (CI), intraoral scanning (IOS) without splinting, intraoral scanning with splinting (MIOS), and stereophotogrammetry (SPG). An industrial blue light scanner was used to generate the baseline scan from the model. The CI was captured with a laboratory scanner. The reference best-fit method was then applied in the computer-aided design (CAD) software to compute the three-dimensional, angular, and linear discrepancies among the four impression techniques. The root mean square (RMS) 3D discrepancies in trueness and precision between the four impression groups were analyzed with a Kruskal-Wallis test. Trueness and precision between single analogs were assessed using generalized estimating equations. RESULTS: Significant differences in the overall trueness (p = .017) and precision (p < .001) were observed across four impression groups. The SPG group exhibited significantly smaller RMS 3D deviations than the CI, IOS, and MIOS groups (p < .05), with no significant difference detected among the latter three groups (p > .05). CONCLUSIONS: Stereophotogrammetry showed superior trueness and precision, meeting misfit thresholds for implant-supported complete arch prostheses. Intraoral scanning, while accurate like conventional impressions, exhibited cross-arch angular and linear deviations. Adding a splint to the scan body did not improve intraoral scanning accuracy.

Influence of scanning protocol on the accuracy of complete-arch digital implant scans: An in vitro study.

OBJECTIVE: This in-vitro study assessed the influence of two intraoral scanning (IOS) protocols on the accuracy (trueness and precision) of digital scans performed in edentulous arches. METHODS: Twenty-two abutment-level master casts of edentulous arches with at least four implants were scanned repeatedly five times, each with two different scanning protocols. Protocol A (IOS-A) consisted of scanning the edentulous arch before inserting the implant scan bodies, followed by their insertion and its subsequent digital acquisition. Protocol B (IOS-B) consisted of scanning the edentulous arch with the scan bodies inserted from the outset. A reference scan from each edentulous cast was obtained using a laboratory scanner. Trueness and precision were calculated using the spatial fit analysis, cross-arch distance, and virtual Sheffield test. Statistical analysis was performed using generalized estimating equations (GEEs). Statistical significance was set at α = .05. RESULTS: In the spatial fit test, the precision of average 3D distances was 45 µm (±23 µm) with protocol IOS-A and 25 µm (±10 µm) for IOS-B (p < .001), and the trueness of average 3D distances was 44 µm (±24 µm) with protocol IOS-A and 24 µm (±7 µm) for IOS-B (p < .001). Cross-arch distance precision was 59 µm (±53 µm) for IOS-A and 41 µm (±43 µm) for IOS-B (p = .0035), and trueness was 64 µm (±47 µm) for IOS-A and 50 µm (±40 µm) for IOS-B (p = .0021). Virtual Sheffield precision was 286 µm (±198 µm) for IOS-A and 146 µm (±92 µm) for IOS-B (p < .001), and trueness was 228 µm (±171 µm) for IOS-A and 139 µm (±92 µm) for IOS-B (p < .001). CONCLUSIONS: The IOS-B protocol demonstrated significantly superior accuracy. Placement of scan bodies before scanning the edentulous arch is recommended to improve the accuracy of complete-arch intraoral scanning.

Effects of erosion and abrasion on resin-matrix ceramic CAD/CAM materials: An in vitro investigation.

The aim of the study was to evaluate the effects of erosion and abrasion on resin-matrix ceramic CAD/CAM materials [CERASMART (GC); VITA ENAMIC (VITA Zahnfabrik); Lava Ultimate (3 M)] in comparison to feldspar ceramic (VITABLOCS Mark II, VITA Zahnfabrik) and resin composite materials (ceram.x universal, Dentsply Sirona). Daily brushing and acid exposure were simulated using a brushing apparatus and a solution of 0.5 vol% citric acid. Microhardness, surface roughness, and substance loss were measured at baseline and after simulation of 1 and 3 years of function. All materials showed a decrease in microhardness after 3 years and an increase in surface roughness (Ra) after 1 and 3 years. The Ra increase was statistically significantly lower for the resin-matrix ceramics than for feldspar ceramic and similar to composite material. After 3 years, only feldspar ceramic showed no significant substance loss. In conclusion, resin-matrix ceramics demonstrate reduced roughening compared to feldspar ceramics, potentially improving restoration longevity by preventing plaque buildup, but differences in abrasion resistance suggest the need for further material-specific research. Future research should aim to replicate clinical conditions closely and to transition to in vivo trials.

Finishing technique effect on strength of zirconia-reinforced lithium silicate ceramic.

The aim of this study was to evaluate the effect of two finishing techniques, glazing or polishing, in comparison with the as-cut condition, on the biaxial-flexural-strength (BFS) of a zirconia-reinforced lithium silicate ceramic (ZLS). Cylinders were milled from CAD/CAM blocks and sliced to obtain disc-shaped specimens (ISO6872:2015). Polished and glazed specimens were processed following the manufacturer's instructions. Thirty-three specimens were obtained for each condition and microstructural and BFS/fractographic characterizations were performed. BFS and roughness data were analyzed using Weibull statistics and ANOVA one-way with Tukey post-hoc test, respectively. While a rougher surface was observed for as-cut specimens, smoother surfaces were observed for polished and glazed ZLS at microscopical evaluation and confirmed through surface-roughness evaluation. X-ray spectra depicted a glass phase for all groups and characteristic metasilicate, lithium disilicate, and lithium phosphate peaks for the as-cut and polished specimens. Glazed specimens showed higher characteristic strength than polished and as-cut specimens, which did not differ significantly. While higher Weibull-modulus was observed for the polished than for the as-cut specimens, no statistically significant differences were noted between glazed and polished, and between glazed and as-cut specimens. ZLS presents higher strength when glazed, and polishing increases the structural reliability of the material relative to the as-cut condition. Both finishing techniques reduced surface roughness similarly.

Influence of different immediate dentin sealing strategies on bond strength of indirect resin nanoceramic restorations.

In this study, we evaluated the effect of four different strategies for bonding a CAD/CAM resin nanoceramic restoration (Lava Ultimate, 3M) to the dentin surface using a universal adhesive (Scotch Bond Universal, 3M) and adhesive resin cement (RelyX Ultimate, 3M) on the shear bond strength (SBS) and failure mode. The strategies comprised: (i) immediate sealing, immediate bonding; (ii) immediate sealing, bonding after 2 weeks with provisional restoration; (iii) immediate sealing with flowable resin composite reinforcement and bonding after 2 weeks with provisional restoration; and (iv) no immediate sealing, and bonding after 2 weeks with provisional restoration. After bonding, all the specimens were thermocycled, shear tests were performed using a universal testing machine, and failure modes were determined using stereomicroscope and scanning electron microscopy. The highest mean SBS was recorded with immediate sealing, immediate bonding strategy. Most adhesive failures with exposed dentinal tubules were noted in specimens exposed to bonding after 2 weeks with no immediate sealing, which was associated with the lowest SBS. Mixed failures predominated in all immediate dentin sealing groups. Immediate sealing with universal adhesives improves SBS, particularly in the single-visit approach, which has shown significantly better performance, whereas the provisional phase has a negative effect.

Comparative Accuracy of Intraoral and Extraoral Digital Workflows for Short Span Implant Supported Fixed Partial Denture Fabrication: An In Vitro Study.

BACKGROUND The advent of digital impressions using computer-aided design and manufacturing technology (CAD/CAM) has simplified and improved the fabrication of implant prostheses in dentistry. The conventional impression has several drawbacks, including tray selection, material type, impression technique, impression disinfection, and cast model storage. The inaccuracies caused by distortion and contraction of impression material can be minimized with digital impressions. This study aimed to compare digital dental impressions of 10 working casts made using the Pindex laser removable die system to fabricate parallel drill channels vs 10 working casts made using the Di-Lok plastic tray removable die system. MATERIAL AND METHODS An implant master die with 2 dental implant analogs was fabricated. Ten working casts using the Pindex laser removable die system with parallel drill channels and 10 working casts using the Di-Lok plastic tray removable die system were fabricated. The working casts were scanned using an extra-oral laboratory scanner and the implant master model was scanned with an intra-oral scanner. RESULTS The properties of the casts made using the 2 systems were evaluated and analyzed with ANOVA and post hoc Tukey test. The mean horizontal linear distances between A1B1 (P<0.021), A2B2 (P<0.018), C1D1 (P<0.026), C2D2 (P<0.03), B1C1 (P<0.01), and mean vertical distances between B1A2 (P<0.015), C1D2 (P<0.001), B1B2 (P<0.028), and C1C2 (P<0.001) were significantly different between the Pindex system and Di-Lok tray system as compared to intra-oral scans. CONCLUSIONS Complete digital workflow with intra-oral scans were more than the partial digital workflow with extra-oral scans for the Pindex system and Di-Lok tray systems.

Letter to editor: Exploring complications following cranioplasty after decompressive hemicraniectomy: A retrospective bicenter assessment of autologous, PMMA and CAD implants.

This study presents a critical analysis of complications following cranioplasty (CP) after decompressive hemicraniectomy, focusing on autologous, polymethylmethacrylate (PMMA), and computer-aided design (CAD) implants. The analysis encompasses a retrospective bicenter assessment, evaluating factors influencing surgical outcomes and emphasizing the significance of material selection in minimizing postoperative complications. The study's comprehensive examination of complication rates associated with various implant materials contributes significantly to understanding CP outcomes. While polymethylmethacrylate (PMMA) and autologous bone flaps (ABFs) exhibited higher rates of surgical site infection (SSI) and explantation, a meta-analysis revealed a contrasting lower infection rate for polyether ether ketone (PEEK) implants. The study underscores the critical role of material selection in mitigating postoperative complications. Despite its strengths, the study's retrospective design, reliance on data from two centers, and limited sample size pose limitations. Future research should prioritize prospective, multicenter studies with standardized protocols to enhance diagnostic accuracy and treatment efficacy in CP procedures.

Can a Point-of-Care 3D Printing Workflow Produce Accurate and Successful Results for Craniomaxillofacial Trauma?

BACKGROUND: Computer-aided design and manufacturing (CAD/CAM) is having a profound impact on craniomaxillofacial surgery, and point-of-care (POC) solutions for repairing facial trauma are starting to emerge. PURPOSE: The purpose of this study was to demonstrate the success and accuracy of a POC 3D printing workflow for craniomaxillofacial trauma. STUDY DESIGN, SETTING, SAMPLE: A retrospective cohort study was undertaken to analyze subjects presenting to a level 1 trauma center after sustaining facial trauma and were then treated using the POC 3D printing workflow. Subjects were excluded if they were not treated with the POC 3D printing workflow, were lost to follow-up, or if clinical data were incomplete. PREDICTOR VARIABLE: Predictor variables included the cause of trauma (mechanism), location of the mandibular fracture, type of fracture, mandibular severity score, and repair error (ie, root mean square error (RMSE) value for planned vs actual outcome). MAIN OUTCOME VARIABLE(S): The primary outcome variables were case success and case error. Success was defined as clinical and radiographic evidence of bony stability at 3 months. Case accuracy was calculated overlaying preoperative plan data to postoperative data generating a numerical value (RMSE value, mm). COVARIATES: Covariates included age (years), gender (male/female), surgery time (mins), and CAD/CAM time (preoperative). ANALYSES: Descriptive statistics were calculated for each variable. Dependence between rates or counts was established using the Wilcoxon rank sum or Fisher's exact test. Linear regression model was computed to discern how predictor variables influence RMSE. A P value < .05 was considered statistically significant. RESULTS: The sample included 27 subjects (19 male/8 female). The average age of all subjects was 46.4 ± 18.0 years. Common mechanisms of injury were assault (33%) and self-inflicted gunshots (SIGSW; 30%), and the average severity score for mandible injury was (13.5 ± 3.3). Ninety-three percent of cases were deemed successful. The average repair accuracy (RMSE value) was 3.4 ± 1.8 mm. A linear regression model indicated those injured by a fall (ß-coefficient 1.99; P = .010), motor vehicle collision (ß-coefficient 1.49; P = .043), or SIGSW (ß-coefficient 2.82; P < .001) correlated with RMSE. CONCLUSION AND RELEVANCE: In-house CAD/CAM technologies can be utilized at the POC to repair complex facial trauma accurately and successfully.

Virtual Surgical Guidance Improves Quality of Life Following Scapular Free-Flap Reconstruction of Maxillary Defects.

BACKGROUND: The best approach to maxillary reconstruction with negative impact on the patient's quality of life (QOL) remains the subject of debate. PURPOSE: This study was designed to evaluate the QOL outcomes following maxillary reconstruction using a scapular-free flap, with and without the computer-aided design and computer-aided manufacturing (CAD/CAM) technique. STUDY DESIGN, SETTING, SAMPLE: A prospective randomized controlled clinical trial was performed following the CONSORT checklist. To be included, patients suffering from maxillary defects without previous surgery or lymph node involvement were selected. Patients with poor oncological prognosis, deficient performance status, preoperative chemotherapy, or radiotherapy, besides vascular contraindications, were excluded. PREDICTOR VARIABLE: The predictor variable was the reconstruction technique, grouped into two equal categories. Patients were randomly assigned to reconstruction with a scapular-free flap, with the control group not utilizing a guide and the study group utilizing a CAD/CAM-customized guide. MAIN OUTCOME VARIABLE: The primary outcome variable was the various domains of QOL, measured using the University of Washington Quality of Life score, 12 months after reconstruction. COVARIATES: Age; sex; scapular flap side; and maxillary defect tumour type, histopathology, side, length, class, sagittal, and axial differential areas were considered. ANALYSES: Shapiro-Wilk and Kolmogorov-Smirnov tests were performed for normality. For comparisons between the two groups, Student's t-test and Mann-Whitney test were used. The category variables were compared using the χ2 test. P ≤ .05 was considered statistically significant. RESULTS: The sample was composed of twenty-two eligible patients, eleven in each group. The mean age of the control group was (50.09 ± 17.14) years, and 45.45% were male, while in the study group, the mean age was (48.36 ± 14.14) years, with 36.36% male. All the patients were evaluated, showing statistically significant differences between control and study groups in terms of pain, appearance, chewing, swallowing, speech, and shoulder (P ≤ .05), indicating that the scapular-free flap with a CAD/CAM osteotomy guide had improved the patient's QOL. CONCLUSION AND RELEVANCE: The findings of this study indicate that virtual surgical planning with a CAD/CAM customized osteotomy guide using a scapular-free flap can improve QOL in maxillary reconstruction in terms of pain, appearance, chewing and swallowing food, pronouncing words, and shoulder QOL outcomes.