Depth of reading within the gingival sulcus of seven intraoral scanners: an in vitro study.

AIM: The present in vitro study aimed to evaluate the depth of reading of intraoral scanners (IOSs) within the gingival sulcus. MATERIALS AND METHODS: A knife-edge preparation for a full crown was performed on a Frasaco model. The gingival sulcus of the scanned model was modified using a dedicated software program (Model Creator, exocad DentalCAD 2.4 Plovdiv) by setting the apical width (AW), coronal width (CW), and gingival sulcus depth (D). Two dental models with different gingival sulcus depths (1 or 2 mm) were printed using the digital light processing (DLP) technique. Each model was scanned 10 times. Seven different IOSs were used: Emerald, Trios 3, Carestream 3600, Dental Wings DWIO, CondorScan, True Definition Scanner (TDS), and Cerec Omnicam. Measurements of D values were performed using 3Shape 3D viewer software. The normality of the data distribution was evaluated using the Shapiro-Wilk test (P < 0.05). The nonparametric Levene's test was used to check for homoscedasticity. The data were statistically analyzed using the Kruskal-Wallis test (α = 0.05) and the Nemenyi test. RESULTS: All IOSs were able to read within the 1-mm-deep gingival sulcus, albeit with some statistically significant differences (P < 0.001). TDS and Trios 3 were able to read within the 2-mm-deep gingival sulcus (P < 0.001). CONCLUSIONS: The depth of reading of different IOSs can vary significantly. In the model with a 2-mm gingival sulcus, even in the absence of oral fluids, the depth of reading was incomplete, suggesting that deep preparations into the gingival sulcus are difficult to detect with IOSs.

Performance of the caries diagnosis feature of intraoral scanners and near-infrared imaging technology-A narrative review.

PURPOSE: To describe and discuss the benefits and drawbacks of various dental caries diagnostic techniques, including the use of intraoral scanners for caries diagnosis based on near-infrared imaging (NIR) technology. MATERIAL AND METHODS: A MEDLINE search from 1980-2023 focused on dental caries diagnostic techniques, emphasizing intraoral scanners using NIR technology. Alternative caries detection methods were also evaluated for their advantages and limitations, enabling a comparison with NIR. The review included traditional caries tools, the latest detection methods, and NIR's role in intraoral scanners, drawing from case reports and both in vivo and in vitro studies. Keywords like "caries detection," "intraoral scanners," and "Near Infrared Imaging (NIRI)" guided the search. After screening titles and abstracts for relevance, full texts with valuable insights were thoroughly analyzed. The data was grouped into three: traditional diagnostics, advanced digital methods, and intraoral scanner-based detection. RESULTS: This comprehensive narrative review described and discussed the current state of dental caries diagnostic methods, given the insufficient number of clinical investigations suitable for a systematic review. Traditional caries diagnosis techniques have shown variable accuracy dependent on a dentist's experience and the potential over-removal of healthy tooth structures. Intraoral scanners have emerged as a novel caries detection method, because of their integration of NIR technology. Various studies have confirmed the efficacy of NIR in detecting interproximal caries and in the early diagnosis of non-cavitated caries. Specifically, intraoral scanners have demonstrated promising results, proving comparable to established diagnostic methods like bitewing radiography. Nevertheless, while the integration of NIR into intraoral scanners seems promising, the technology still faces challenges, notably its accuracy in detecting secondary and subgingival cavities. However, with anticipated integrations of AI, NIR in intraoral scanners could revolutionize early caries detection. CONCLUSIONS: Intraoral scanners with NIR technology offer non-destructive imaging, real-time lesion visuals, and enhanced patient communication. Although comparable to bitewing radiography in some studies, a universally accepted diagnostic tool is lacking. Future research should compare them with existing methods, focusing on clinical outcomes, cost-effectiveness, and patient acceptance.

Potential of intraoral optical scanning to evaluate motor skills' improvement for tooth preparation: A prospective cohort study.

INTRODUCTION: This prospective cohort study investigated the potential of digital assessment using intraoral scanning (IOS) combined with software analysis (prepCheck) to evaluate the outcome of repetitive tooth preparation and its influence on the acquisition of motor skills in dental students. MATERIALS AND METHODS: Twenty-six students completed 177 full-crown preparations of the same tooth in six practice sessions followed by a final examination. Preparations were assessed digitally using prepCheck and conventionally by calibrated faculty instructors. In addition, students assessed their own performance and this was compared with the instructors' assessments. RESULTS: Conventional assessment showed that students preparations improved over time, with 43.5% of students receiving score 2 (highest grade) at the fifth practice session. With the prepCheck assessment, statistically significant improvements indicated by an enlarged area within the tolerance range set at 0.2 mm were found between the first and the second practice session (7.5% improvement; 95% CI: 2.2%, 12.7%, p = 0.006), and between the first run and the final exam preparation (6.7%; 95% CI: 1.7%, 12.5%, p = 0.011). Agreement between instructor/student assessments was best immediately after students received visual feedback using prepCheck (76% agreement; Spearman's rho 0.78). CONCLUSION: These data indicate that IOS technology was useful for student's self-evaluation by visual feedback.

Trueness and Precision Achieved With Conventional and Digital Implant Impressions: A Comparative Investigation of Stone Versus 3-D Printed Master Casts.

OBJECTIVE: To analyze implant casts obtained from intraoral optical scanning and conventional impressions. MATERIALS AND METHODS: Ten optical scans (test) and ten conventional polyether impressions (control) were obtained from a two-implant reference model. Ten casts each were manufactured additively or from stone. All casts were digitized and virtually superimposed to the digital reference (trueness) applying a best-fit algorithm, and secondary analysis for intra-group comparisons (precision). The signed nearest neighbor distance of each surface point (FDI:24/26) was computed and deviations of the three-dimensional vectors (X,Y,Z) analyzed. The groups were compared with the Wilcoxon's rank sum test. RESULTS: The printed casts had mean deviations of 106.0µm and the stone casts 187.9µm compared to the reference. Controls had significantly higher deviations and dispersion (p⟨0.001). The printed casts showed mean intra-group deviations of 149.8µm and the stone casts 181.2µm without significant differences (p=0.162). There was no statistically significant difference in any of the vector analyses (X:p=0.105, Y:p=0.089, Z:p=0.123). CONCLUSION: Optical scanning seems to be an alternative to conventional impressions in terms of trueness and precision of implant master casts, simulating the scenario of a three-unit implant-supported fixed dental prosthesis. Digitally manufactured master casts might serve as reliable reference for the final restorations.

Influence of intraoral scanning on the quality of preparations for all-ceramic single crowns.

OBJECTIVES: To evaluate the influence of intraoral scanning on the quality of preparations for all-ceramic single crowns. MATERIAL AND METHODS: A total of 690 randomly selected and anonymized in vivo single crown preparations were examined. Three hundred twenty-three preparations were directly recorded with an intraoral scanner (group IS). Data from plaster casts digitized by a laboratory scanner (group ID; N = 367) served as control. Comparisons included convergence angle, marginal design, marginal substance reduction, homogeneity of the finish line, and undercuts. Evaluation was performed using fully automated specialized software. Data were analyzed applying Kolmogorov-Smirnov, Mann-Whitney U test, and Fisher's exact test. Level of significance was set at p < 0.05. RESULTS: Convergence angle was above optimum in both groups, but significantly larger for group IS (p < 0.001). Marginal design was more ideal in group IS concerning the absence of featheredge design (p < 0.001) and reverse bevel (p = 0.211). Marginal substance reduction was closer to prerequisites for all-ceramic restorations in group IS (p < 0.001). Finish lines were more homogeneous in group IS regarding the uniformity of their course (p < 0.001). Undercuts were more frequently found in group ID than in group IS (p < 0.001). CONCLUSIONS: Intraoral scanning of prepared teeth has positive impact on the quality of preparations for all-ceramic single crowns regarding marginal substance reduction, marginal design, homogeneity of the finish line, and undercuts. CLINICAL RELEVANCE: Accurate preparation design represents a fundamental condition for success of ceramic crowns. Since there is potential for optimization, intraoral scanning might enhance preparation quality providing instant visual feedback.

Technical note on introducing a digital workflow for newborns with craniofacial anomalies based on intraoral scans - part I: 3D printed and milled palatal stimulation plate for trisomy 21.

BACKGROUND: Advanced digital workflows in orthodontics and dentistry often require a combination of different software solutions to create patient appliances, which may be a complex and time-consuming process. The main objective of this technical note is to discuss treatment of craniofacial anomalies using digital technologies. We present a fully digital, linear workflow for manufacturing palatal plates for infants with craniofacial anomalies based on intraoral scanning. Switching to intraoral scanning in infant care is advantageous as taking conventional impressions carries the risk of impression material aspiration and/or infections caused by material remaining in the oronasal cavity. MATERIAL AND METHODS: The fully digital linear workflow presented in this technical note can be used to design and manufacture palatal plates for cleft palate patients as well as infants with functional disorders. We describe the workflow implemented in an infant with trisomy 21. The maxilla was registered using a digital scanner and a stimulation plate was created using dental CAD software and an individual impression tray module on a virtual model. Plates were manufactured using both additive and subtractive methods. Methacrylate based light curing resin and Poly-Ether-Ether-Ketone were the materials used. RESULTS: The palatal area was successfully scanned to create a virtual model. The plates fitted well onto the palatal area. Manual post-processing was necessary to optimize a functional ridge along the vestibular fold and remove support structures from the additively manufactured plate as well as the milled plate produced from a blank. The additively manufactured plate fitted better than the milled one. CONCLUSION: Implementing a fully digital linear workflow into clinical routine for treatment of neonates and infants with craniofacial disorders is feasible. The software solution presented here is suitable for this purpose and does not require additional software for the design. This is the key advantage of this workflow, which makes digital treatment accessible to all clinicians who want to deal with digital technology. Whether additive or subtractive manufacturing is preferred depends on the appliance material of choice and influences the fit of the appliance.

Marginal and internal fit of CAD/CAM fiber post and cores.

AIM: To evaluate the marginal adaptation and internal fit of milled fiber post and cores using different scanning methods. MATERIALS AND METHODS: Thirty typodont tooth models (Nissin) with pulp cavity were endodontically treated and prepared to receive 30 fabricated fiber post and cores. Three different methods of scanning were used (n = 10): an intraoral scanner (IOS) (Trios 3; 3Shape) to directly digitalize the post space (Group T) and a laboratory scanner to indirectly digitalize the resin pattern (Group RP) and the silicone impression (Group S) of the post space. All the specimens were examined using an optical microscope for the measurement of the vertical marginal discrepancy (VMD), and five in each group were scanned using microcomputed tomography (µCT) for the assessment of the VMD, the internal fit at the corner (IFC), post apex (PA), and at four horizontal cross-sections (CS1-4) inside the canal. All data were analyzed using mixed-design ANOVA, followed by pairwise testing to identify the differences (α = 0.05). RESULTS: Statistical analysis revealed that Group T was associated with the smallest cement space compared with Group RP (P = 0.001) and Group S (P < 0.001) for VMD using µCT or direct microscopy (OM) (P < 0.001). Similarly, the cement space for Group T was smaller than that of Group S (P = 0.039) when measured at the IFC (µCT), and smaller than Group RP (P = 0.025) when measured at CS1-4 (µCT), with CS1 larger than CS3 (P = 0.015). There was no significant difference at PA (P = 0.271). CONCLUSION: Better adaptation was achieved with a complete digital workflow. Scanning the resin pattern or the silicone impression introduced more variables in the digital process or milling of a one-piece fiber post and core.

Digital Tissue Preservation Concept: A Workflow for Guided Immediate Implant Placement and Restoration.

The digital workflow presented here allows for fabrication and placement of a definitive custom abutment at the time of tooth extraction and guided immediate implant placement, thus preserving soft tissue anatomy. Since abutment design was based on the shape of the original tooth, it represented a de facto emergence-analog that provided ideal soft tissue support. The approach of superposing and merging of custom abutment design data with data captured intraorally after abutment placement enabled a digital impression without gingival displacement and associated trauma. The generated data facilitated the fabrication of a precisely fitting restoration concurrent with the implant healing period.

Two digital strategies in modern implantology - root-analogue implants and the digital one-abutment/one-time concept.

The irreversible trend toward digitization in dentistry and dental technology has resulted in technical progress and continuous changes to conventional workflows. In particular, implantology and prosthetics have benefited from a multitude of interesting new possibilities. Three-dimensional (3D) computed radiography and digital surface scanning can be invaluable in terms of backward planning and making implant surgery and denture fabrication more predictable. In this context, two digital implant-prosthetic treatment strategies are presented that allow for an efficient digital workflow while ensuring a minimally invasive surgical procedure. By means of digital intraoperative scanning of the implant position, the digital one-abutment/one-time concept allows for the insertion of computer-aided design/computer-aided manufacturing (CAD/CAM)-manufactured single crowns instantly after uncovering the implant. The second approach uses 3D radiographic data to preoperatively manufacture a one-piece root-analogue implant (RAI) and insert it immediately after tooth extraction. Both ideas promise some advantages in terms of quality and preservation of periimplant tissues as well as a noticeable reduction in overall treatment time.

Automatic removal of soft tissue from 3D dental photo scans; an important step in automating future forensic odontology identification.

The potential of intraoral 3D photo scans in forensic odontology identification remains largely unexplored, even though the high degree of detail could allow automated comparison of ante mortem and post mortem dentitions. Differences in soft tissue conditions between ante- and post mortem intraoral 3D photo scans may cause ambiguous variation, burdening the potential automation of the matching process and underlining the need for limiting inclusion of soft tissue in dental comparison. The soft tissue removal must be able to handle dental arches with missing teeth, and intraoral 3D photo scans not originating from plaster models. To address these challenges, we have developed the grid-cutting method. The method is customisable, allowing fine-grained analysis using a small grid size and adaptation of how much of the soft tissues are excluded from the cropped dental scan. When tested on 66 dental scans, the grid-cutting method was able to limit the amount of soft tissue without removing any teeth in 63/66 dental scans. The remaining 3 dental scans had partly erupted third molars (wisdom teeth) which were removed by the grid-cutting method. Overall, the grid-cutting method represents an important step towards automating the matching process in forensic odontology identification using intraoral 3D photo scans.

Impact of Scanbody Geometry and CAD Software on Determining 3D Implant Position.

The implementation of CAD software in the digital production of implant prosthetics stands as a pivotal aspect of clinical dentistry, necessitating high precision in the alignment of implant scanbodies. This study investigates the influence of scanbody geometry and the method of superimposing in CAD software when determining 3D implant position. A standardized titanium model with three bone-level implants was digitized to create reference STL files, and 10 intraoral scans were performed on Medentika and NT-Trading scanbodies. To determine implant position, the generated STL files were imported into the Exocad CAD software and superimposed-automatically and manually-with the scanbody geometries stored within the software's shape library. Position accuracy was determined by a comparison of the 3D-defined scanbody points from the STL matching files with those from the reference STL files. The R statistical software was used for the evaluation of the data. In addition, mixed linear models and a significance level of 0.05 were applied to calculate the p-values. The manual overlay method was significantly more accurate than the automatic overlays for both scanbody types. The Medentika scanbodies showed slightly superior precision compared to the NT-Trading scanbodies. Both scanbody geometry and the type of alignment in the CAD software significantly affect digital workflow accuracy. Manual verification and adjustment of the automatic alignment process are essential for precise implant positioning.

In Vitro Trueness and Precision of Intraoral Scanners in a Four-Implant Complete-Arch Model.

(1) Background: New intraoral (IOS) and laboratory scanners appear in the market and their trueness and precision have not been compared. (2) Methods: Seven IOS and two laboratory scanners were used to scan a mandibular edentulous model with four parallel internal hexagon implant analogues and PEEK scan bodies. Digital models in Standard Tessellation Language (STL) were created. The master model with the scan bodies was scanned (×10) with a computerized numerical control 3D Coordinate Measuring Machine (CMM). The short (distances of adjacent scan posts) and long distances (distances of the scan posts with non-adjacent sites in the arch) among the centroids of the four analogues were calculated using CMM special software. Trueness (comparisons with the master model) and precision (intragroup comparisons) were statistically compared with ANOVA, chi-square and Tukey tests. (3) Results: Laboratory scanners had the best trueness and precision compared to all IOSs for long distances. Only iTero (Align Technologies Inc., Milpitas, CA, USA) had comparable trueness with one laboratory scanner in short and long distances. For short distances, CS3600 (Carestream Health, Inc., Rochester, NY, USA), Omnicam, Primescan (Sirona Dental Sys-tems GmbH, Bens-heim, Germany) and TRIOS 4 (3Shape A/S, Copen-hagen, Denmark) had similar trueness to one laboratory scanner. From those, only Omnicam and Primescan had similar precision as the same laboratory scanner. Most IOSs seem to work better for smaller distances and are less precise in cross-arch distances. (4) Conclusions: The laboratory scanners showed significantly higher trueness and precision than all IOSs tested for the long-distance group; for the short distance, some IOSs were not different in trueness and precision than the laboratory scanners.

Comparison of the measurement error of optical impressions obtained with four intraoral and one extra-oral dental scanners of post and core preparations.

Statement of problem: Innovations in intraoral scanner (IOS) technology are opening up ever more indications for computer-aided design and manufacturing (CAD-CAM). The manufacturers claim that the latest generations of scanners allow the digitizing of root canal preparations. However, there is a lack of studies evaluating the quality of the optical impressions made for this type of treatment. Purpose: The purpose of this study was to evaluate the measurement error of 4 IOSs and a laboratory scanner used for the digitizing of root canal preparations and to highlight the effect of the presence or absence of adjacent teeth on the quality of the digital model. Material and methods: Two models: one presenting adjacent teeth, one without adjacent teeth, both presenting a 10 mm deep nominal conical pit mimicking a root canal preparation were fabricated. Each model was scanned 10 times with a laboratory scanner (E3) and 4 intraoral scanners (Primescan, Omnicam, TRIOS 4, and Medit i700). The digital models were then exported as standard tessellation language (STL) files and analyzed to evaluate the mean measurement error of the digitizing of the root preparation at three different depths: 0-3 mm, 3-6 mm, and 6-9 mm. Significant differences were assessed with a 1-way ANOVA test and the pairwise comparison between scanners was done by Tukey's multiple comparison test. Results: Statistical differences were found between scanners (P < 0.05). The mean measurement error ranged from 9.8 ± 0.5 µm with the Medit i700 to 28.2 ± 10 µm with the E3. The E3 and Omnicam scanners were in some cases incapable of digitizing the conical preparation in its entirety. The group Primescan, TRIOS 4, and Medit i700 showed minimally significant differences. The presence of adjacent teeth had a negative effect on the model quality for some scanners, mainly because of the obstruction of the IOS's head. Conclusions: Significant differences were found among the dental scanners used for digitizing root canal preparations. Optical impressions with modern intraoral scanners seem to be an adapted method of registration of root canal preparation for post-and-copings of post-and-cores fabrication.

A novel reference model for dental scanning system evaluation: analysis of five intraoral scanners.

PURPOSE: The aim of this in vitro study was to investigate the accuracy (trueness and precision) of five intraoral scanners (IOS) using a novel reference model for standardized performance evaluation. MATERIALS AND METHODS: Five IOSs (Medit i500, Omnicam, Primescan, Trios 3, Trios 4) were used to digitize the reference model, which represented a simplified full-arch situation with four abutment teeth. Each IOS was used five times by an experienced operator, resulting in 25 STL (Standard Tessellation Language) files. STL data were imported into 3D software (Final Surface®) and examined for inter- and intra-group analyses. Deviations in the parameter matching error were calculated. ANOVA F-test and Kruskal-Wallis test were applied for inter-group comparisons (α = .05); and the coefficient of variation (CV) was calculated for intra-group comparisons (in % ± SD). RESULTS: Primescan (matching error value: 0.015), Trios 3 (0.016), and Trios 4 (0.018) revealed comparable results with significantly higher accuracy compared to Medit i500 (0.035) and Omnicam (0.028) (P < .001). For intra-group comparison, Trios 4 demonstrated the most homogenous results (CV 15.8%). CONCLUSION: The novel reference model investigated in this study can be used to assess the performance of dental scanning technologies in the daily routine setting and in research settings.

Development of a photothermal bead-based nucleic acid amplification test (pbbNAAT) technique for a high-performance loop-mediated isothermal amplification (LAMP)-based point-of-care test (POCT).

We have developed a novel molecular diagnostic platform (photothermal bead-based nucleic acid amplification test; pbbNAAT) that greatly improves the low sensitivity of direct loop-mediated isothermal amplification (LAMP) and allows for specific detection of LAMP amplicons in complex samples. The pbbNAAT integrates specific ligand-functionalized polypyrrole-coated iron oxide particles (PPy@IOs) capable of photothermal conversion and single-molecule magnetic capture of target analytes, the released nucleic acid, and LAMP-amplified products under external light energy control and magnetic manipulations. This allows for sample pretreatment, pbbLAMP amplification, and subsequent amplicon detection with bead-based ELISA in a one-stop microreactor without loss. In addition, photonic heating with PPy@IOs and external light control provide instant and uniform heating for thermolysis and pbbLAMP implementations. Moreover, it generates higher primer annealing stringency for LAMP primers in pbbLAMP; thus, it can detect pathogen-specific DNA accurately and promptly in pathogen-spiked complex materials. The sample pretreatment procedure of pbbNAAT can greatly reduce inhibitors originating from complex samples, which enables the maintenance of maximal enzyme activities for highly sensitive detection. More importantly, the pbbLAMP assay coupled with magnetic capture permits subsequent bead-based ELISA detection to determine true positive LAMP amplicons on PPy@IOs. The pbbNAAT platform has a high tolerance to inhibitors originating from complex samples, high analytical specificity, and limitation of detection (LoD) as low as 8 CFU/reaction to detect E. coli spiked in human whole blood, bovine milk, and can be completed in less than 1 h. Therefore, we believe that pbbNAAT can serve as a suitable direct LAMP platform for on-site POCTs.

Analysis of The Reproducibility of Subgingival Vertical Margins Using Intraoral Optical Scanning (IOS): A Randomized Controlled Pilot Trial.

BACKGROUND: The aim of this randomized controlled trial was to evaluate the capability of an IOS (Intra Oral Scanner) device, used in standardized conditions, to detect margins of abutments prepared with knife-edge finishing line located at three different levels in relation to the gingival sulcus. METHODS: sixty abutment teeth for treatment with full crowns were selected and randomly divided in three groups accordingly to the depth of the finishing line: Group A: supragingival margin; Group B: 0.5-1.0 mm into the sulcus; Group C: 1.5-2.0 mm into the sulcus. Temporary crowns were placed for two weeks and then digital impressions (Aadva IOS 100, GC, Japan) were made of each abutment. As controls, analog impressions were taken, poured, and scanned using a laboratory scanner (Aadva lab scanner, GC, Japan). Two standard tessellation language (STL) files were generated for each abutment, subsequently processed, and superimposed by Exocad software (Exocad GmbH, Darmstadt, Germany), applying the "best-fit" algorithm in order to align the scan of the conventional with the digital impressions. The distances between each preparation margin and the adjacent gingival tissue were measured. Four measures were taken, two interproximally and buccally, for a total of six measures of each abutment considering three modes of impressions. The data were statistically evaluated using two-way analysis of variance (ANOVA) for each site and the Bonferroni test. RESULTS: there was no difference between the two kinds of impression in Group A in both sites, in Group B a difference of 0.483 mm and 0.682 mm at interproximal and buccal sites, respectively, and in Group C 0.750 mm and 0.964 mm at interproximal and buccal sites, respectively. The analysis performed on a site level (mesial/distal/vestibular) for the depth of both vertical preparations revealed significant differences (p < 0.0001). After a post hoc analysis (Bonferroni), vestibular sites of the shallow vertical preparations resulted in significantly lower values compared to the other sites prepared deeply. CONCLUSIONS: the results showed that the location of the margin is an important factor in making a precise and complete impression when IOS (Intra Oral Scanner) is used. Moreover, deep preparation into the sulcus is not recommended for IOS (Intra Oral Scanner) impressions.

Influence of implant scanbody material, position and operator on the accuracy of digital impression for complete-arch: A randomized in vitro trial.

PURPOSE: To evaluate the influence of implant scanbody (ISB) material, position and operator on the accuracy of a confocal microscopy intraoral scanning (IOS) for complete-arch implant impression. METHODS: An edentulous maxillary model with 6 internal hexagonal connection analogues was scanned with an extraoral optical scanner to achieve a reference file. Three ISBs made of different materials (polyetheretherketone (Pk), titanium (T) and Pk with a titanium base (Pkt)) were scanned with IOS by 3 operators. The resulting 45 test files were aligned to the reference file with a best fit algorithm. Linear (ΔX, ΔY and ΔZ-axis) and angular deviations (ΔANGLE) were assessed. Absolute values of the linear discrepancies were summed up to obtain a global measure of linear absolute error (ΔASS). Influence of ISB material, position and operator was statistically assessed using the mixed general linear model. RESULTS: At multivariate analysis, whenΔASS was considered as response variable, it was identified a significant influence of material (p<0.0001) and position (p=0.0009) while no significant operator effect was detected. When ΔANGLE was considered as response variable, material and position significantly influenced the expected ΔANGLE (p=0.0232 and p<0.0001) and no operator effect was identified. CONCLUSIONS: The investigated IOS for complete-arch digital impression was influenced by the ISB material with peek reporting the best results on both linear and angular measurements followed by titanium, peek-titanium resulting as the less accurate. Implant angulation affected significantly the linear deviations while implant position the angular deviations. Operator did not show any significant effect on the IOS accuracy.

Full arch precision of six intraoral scanners in vitro.

PURPOSE: Intraoral scanners may offer an alternative to traditional impressions. That intraoral scanners produce precise scans is essential. Popular methods used to evaluate precision tend to rely on mean distance deviation between repeated scans. Mean value measurements may underestimate errors resulting in misleading conclusions and clinical decisions. This study investigated the precision of six intraoral scanners using the traditional method of measuring mean error, and a proposed method considering only the most extreme and clinically relevant aspects of a scan. METHODS: An edentulous model was scanned five times using six intraoral scanners. The repeated scans were aligned, uniformly trimmed and mean surface deviation measured across all 20 scan combinations within each scanner group. All scan combinations were then measured by arranging scan vertices from greatest to smallest unsigned distance from its compared scan and measuring the median value within the 1% of most greatly deviating points. Traditional mean deviation results and upper-bound deviations were compared. RESULTS: The upper-bound deviation within a scan reported errors up to two times greater than those found when measuring global mean distances. Results revealed clinically relevant errors of more than 0.3mm in scans produced by the Planmeca and Dentalwings scanners, findings not seen when measuring mean distance error of the complete scan. CONCLUSIONS: Upper-bound deviation of a cropped scan may provide a clinically useful metric for scanner precision. The Aadva, 3Shape, CEREC and TDS produced scans potentially appropriate for clinical use while Planmeca and Dentalwings produced deviations greater than 0.3mm when measuring the upper-bound deviation.

Development of artificial neural network model for prediction of post-streptococcus mutans in dental caries.

BACKGROUND AND OBJECTIVE: Streptococcus mutans is the primary initiator and most common organism associated with dental caries. Prediction of post-Streptococcus mutans favours in the selection of appropriate caries excavation method which eventually results in meliorate caries-free cavity preparation for restoration. The objective of this study is to predict the post-Streptococcus mutans prior to dental caries excavation based on pre- Streptococcus mutans using iOS App developed on Artificial Neural Network (ANN) model. METHODS: For the current research work, children with occlusal dentinal caries lesion were chosen, 45 primary molar teeth cases were studied. Caries excavation was done with carbide bur, polymer bur and spoon excavator. The colony forming units for pre and post-Streptococcus mutans were recorded, data emanating from clinical trials was employed to develop the ANN models. ANN models were trained, validated and tested with the registered clinical data using different ANN architectures. RESULTS: Feedforward backpropagation ANN model with an architecture of 4-5-1, predicts post-Streptococcus mutans with an efficiency of 0.99033, mean squared error and mean absolute percentage error for testing cases were 0.2341 and 4.967 respectively. CONCLUSIONS: Caries excavation methods and pre-Streptococcus mutans are feed as inputs, while post-Streptococcus mutans as targets to develop ANN model. Based on the developed ANN model, an ingenious iOS App was developed, the global clinician may utilize the App to meticulously predict post-Streptococcus mutans on iPhone based on pre-Streptococcus mutans, which in turn aids in decision making for the selection of caries excavation method. This study manifests the potential application of iOS App with built-in ANN model in efficiently predicting the post-Streptococcus mutans. Also, the study extends scope for applications of iOS App with built-in ANN models in clinical medicine.

Precision of maxillo-mandibular registration with intraoral scanners in vitro.

PURPOSE: To compare the precision of maxillo-mandibular registration and resulting full arch occlusion produced by three intraoral scanners in vitro. METHODS: Six dental models (groups A-F) were scanned five times with intraoral scanners (CEREC, TRIOS, PLANMECA), producing both full arch and two buccal maxillo-mandibular scans. Total surface area of contact points (defined as regions within 0.1mm and all mesh penetrations) was measured, and the distances between four pairs of key points were compared, each two in the posterior and anterior. RESULTS: Total surface area of contact points varied significantly among scanners across all groups. CEREC produced the smallest contact surface areas (5.7-25.3mm2), while PLANMECA tended to produce the largest areas in each group (22.2-60.2mm2). Precision of scanners, as measured by the 95% CI range, varied from 0.1-0.9mm for posterior key points. For anterior key points the 95% CI range was smaller, particularly when multiple posterior teeth were still present (0.04-0.42mm). With progressive loss of posterior units (groups D-F), differences in the anterior occlusion among scanners became significant in five out of six groups (D-F left canines and D, F right canines, p<0.05). CONCLUSIONS: Maxillo-mandibular registrations from three intraoral scanners created significantly different surface areas of occlusal contact. Posterior occlusions revealed lower precision for all scanners than anterior. CEREC tended towards incorrect posterior open bites, whilst TRIOS was most consistent in reproducing occluding units.