Intraoral Scanner Research Articles

Comparison of Direct Intraoral Scan and Traditional Impression for CAD/CAM Mandibular Overdenture Base: RCT on Peri-implant Marginal Bone Changes.

This study aimed to evaluate the impact of digital vs traditional impression techniques on peri-implant vertical bone resorption in the creation of mandibular overdenture bases supported by four implants using CAD/CAM technology. Twenty edentulous patients were placed in four mandibular implants and randomly divided into groups: (A) the control group (CIG) (n = 10); patients obtained CAD/CAM denture base using conventional impression technique and group (B) the study (DIG) group (n = 10); patients obtained CAD/CAM denture base using digital impression technique. Peri-implant vertical bone height was measured immediately (T0), 6 (T6), and 12 (T12) months after insertion. Peri-implant vertical bone loss (VBL) was calculated first 6 months (T1), the second 6 months (T2), and 1 year (T3) after insertion. For both groups, the survival rates of inserted implants were 100%. The amount of VBL in the first year in both groups was within normal ranges. In both groups, VBL significantly decreased over time. The control group recorded significantly higher VBL than (DIG) group at T2 (p = 0.006) and at T3 (p = 0.005). Digital intraoral scanning technique may be considered a more beneficial registration method than traditional impression technique for the construction of CAD/CAM 4-implant-assisted overdenture base regarding the preservation of vertical bone levels. Both digital intraoral scanners and conventional impression techniques can be used for the construction of CAD/CAM-implant-assisted overdenture bases regarding the preservation of peri-implant vertical bone resorption. How to cite this article: Seifeldeen AR, Aboelez MA, Gebreel AA, et al. Comparison of Direct Intraoral Scan and Traditional Impression for CAD/CAM Mandibular Overdenture Base: RCT on Peri-implant Marginal Bone Changes. J Contemp Dent Pract 2024;25(6):527-534.

Smartphone‐based scans of palate models of newborns with cleft lip and palate: Outlooks for three‐dimensional image capturing and machine learning plate tool

AbstractObjectivesTo evaluate the performance of smartphone scanning applications (apps) in acquiring 3D meshes of cleft palate models. Secondarily, to validate a machine learning (ML) tool for computing automated presurgical plate (PSP).Materials and MethodsWe conducted a comparative analysis of two apps on 15 cleft palate models: five unilateral cleft lip and palate (UCLP), five bilateral cleft lip and palate (BCLP) and five isolated cleft palate (ICP). The scans were performed with and without a mirror to simulate intraoral acquisition. The 3D reconstructions were compared to control reconstructions acquired using a professional intraoral scanner using open‐source software.ResultsThirty 3D scans were acquired by each app, totalling 60 scans. The main findings were in the UCLP sample, where the KIRI scans without a mirror (0.22 ± 0.03 mm) had a good performance with a deviation from the ground truth comparable to the control group (0.14 ± 0.13 mm) (p = .653). Scaniverse scans with a mirror showed the lowest accuracy of all the samples. The ML tool was able to predict the landmarks and automatically generate the plates, except in ICP models. KIRI scans' plates showed better performance with (0.22 ± 0.06 mm) and without mirror (0.18 ± 0.05 mm), being comparable with controls (0.16 ± 0.08 mm) (p = .954 and p = .439, respectively).ConclusionsKIRI Engine performed better in scanning UCLP models without a mirror. The ML tool showed a high capability for morphology recognition and automated PSP generation.

Clinical and radiographic assessment of gummy smile patients with altered passive eruption: a cross-sectional study in a Thai population.

The study aimed to evaluate the clinical crown length (CCL) among patients diagnosed with altered passive eruption (APE), the causes of a gummy smile, the prevalence of APE, and the correlation between parameters. A total of 86 gummy smile patients (516 teeth) underwent clinical examination and assessment using cone-beam computed tomography (CBCT), photography, and intraoral scanning. Significantly shorter CCL and distance between the cementoenamel junction and bone crest (CEJ-BC) were observed among APE-affected teeth (p < 0.05). Among the patients, 56.1% of patients were diagnosed with APE, and most of them were affected by a combination of APE and hypermobile upper lip (HUL). Based on 183 APE-affected teeth, the prevalence of APE types and subtypes was as follows: APE1A (96; 19.3%), APE1B (78; 15.9%), APE2A (8; 1.6%), and APE2B (1; 0.2%). Positive correlations were found between keratinized gingival width (KGW) and bone thickness (BT), while negative correlations were observed between gingival thickness (GT) and BT. Shorter CCL and CEJ-BC were the highlighted features of APE. APE affected approximately half of the gummy smile patients, with most of them presenting with a combination of HUL. Almost teeth affected by APE were classified as Type I, with a nearly equal distribution between subtypes A and B. The clinical and radiographic features of APE contribute to a better understanding of this condition and facilitate the management of patients affected by APE. Approximately half of gummy smile patients will require multidisciplinary treatment.

3D-Printed Complete Dentures: A Review of Clinical and Patient-Based Outcomes.

There has recently been an increasing trend to shift the fabrication of complete dentures from conventional to digital workflows to shorten the treatment time and increase patient comfort and satisfaction. Digital fabrication of complete dentures can be achieved either by a subtractive process (milling)or by an additive technique (3D printing). The milling process offers numerous advantages; however, they require large-size production machines and are associated with low production efficiency, increased cost, limited block size, and a considerable waste of material. On the other hand, 3D printing technology can potentially offer the benefits of lower manufacturing and equipment costs, good surface details, and lower material waste.Hence, 3D printing is being considered lately by some researchers as a valid choice for manufacturing digital dentures. Therefore, the aim of the current review was to identify and highlight studies on 3D-printed dentures, mainly those investigating clinical and patient-centered outcomes. A search was conducted using thedatabasesPubMed/MEDLINE, Cochrane Library, Embase, and Google Scholar. After applying the inclusion and exclusion criteria, a total of 16 studies that investigated clinical outcomes (masticatory efficiency, biting force, retention and stability, computerized occlusal analysis, and post-insertion maintenance) as well as patient-based outcomes (patient satisfaction, oral health-related quality of life (OHRQoL), patient-related complications, patient preference, and willingness to pay) were included. After a thorough review and discussion of these articles, it could be concluded that 3D printing of complete dentures offers many advantages from both a clinical and patient-based perspective. Retention and comfort with 3D-printed dentures were found to be comparable or even superior to conventional dentures. Moreover, retention of 3D-printed dentures constructed from conventional impressions and digitized casts demonstrated improved retention when compared to a protocol adopting intraoral scanning (digital impressions). Masticatory efficiency, biting force, OHRQoL, and patient satisfaction with 3D-printed dentures varied and were inconsistent among the included studies. Most of the studies reported positive results in the different domains and assessed aspects, while others reported some concerns (especially in terms of aesthetics and phonetics). With regard to post-insertion maintenance, printed dentures showed comparable results to conventional dentures in the short term. The technique seems promising with numerous benefits; however, further clinical research with larger sample sizes and longer follow-up periods is still needed to confirm these conclusions and address the potential concerns.

Establishing a CAD-CAM workflow for stabilization appliances (Michigan splints).

Stabilization appliances (Michigan splints) are considered well-studied and widely adopted for managing bruxism and temporomandibular disorders (TMDs). Traditionally, these appliances have been fabricated by wax modeling and pressing resin onto casts made from irreversible hydrocolloid or silicone impressions. This article provides a detailed description of an all-digital workflow that uses intraoral scanning and computer-aided design (CAD) software to design a stabilization splint on a digital cast that can be manufactured autonomously by a computer-aided manufacturing (CAM) grinding machine in a subtractive procedure. The workflow is applicable to both dentists and technicians. Special attention is given to aspects and procedures that are important for the successful fabrication of the splint. Working without a cast can save time and money, and the use of CAD-CAM technology provides a homogeneous splint material quality.

Revolutionizing Periodontics: The Impact of Digitalization on Diagnosis and Treatment

The objective of this review is to explore the impact of digitalization on periodontics, with a particular focus on its role in enhancing both diagnosis and treatment. Drawing from a range of recent technological advancements, the study reviews the implementation of advanced imaging techniques and artificial intelligence (AI) in clinical practice. Key digital tools such as cone-beam computed tomography (CBCT), digital intraoral scanners, computer-aided design and manufacturing (CAD/CAM), and 3D printing are examined for their contributions to the field. The results indicate that the integration of CBCT and digital intraoral scanners enables precise early detection of periodontal diseases, while AI refines diagnostics through predictive analytics and facilitates personalized treatment plans. Additionally, CAD/CAM and 3D printing technologies support minimally invasive procedures and the creation of custom dental prosthetics, leading to improved patient outcomes. Overall, the review highlights the significant potential of digital tools to optimize clinical workflows and elevate patient care standards, in alignment with contemporary policies aimed at advancing healthcare through technology.

A scanning electron microscope evaluation of surface roughness of different clear aligners – A comparative in-Vitro study

Clear aligner are thermoplastic polyurethane materials which produces small increments of tooth movements by each aligner tray. Clinical effectiveness of the treatment largely depend on the mechanical properties of the material. The use of scanning electron microscopy (SEM) in invitro environment allows to evaluate the surface morphology of the aligners The aim of the study is to compare the surface roughness of different types of clear aligners after thermoforming and after invitro aging. A sample of 15 aligners from Group A (DURAN), Group B (ERKODUR), Group C (MONOFLEX) were taken for this study. After screening the subjects were scanned by intraoral scanner and STL file were imported to Maestero 3D software. Then resin models were printed and aligners were fabricated in the models by thermoforming machine. The first set of aligners were scanned by Scanning Electron Microscope and another set of aligners were placed in chewing simulator for simulating intraoral environment. Then the second set of aligners were sent for SEM evaluation. Mean comparison of surface roughness and root mean square surface roughness was compared by paired t test and comparison among the groups was done by one way ANOVA test. The surface roughness of both aligners increased after thermoforming. This could be due to thermoforming process which could be due to temperature variation. After the ageing of the aligners in the invitro environment, there is homogenous and smooth layer of the aligner surfaces which could be due to adhesion of biofilm and polishing effect by chewing strokes.

Effects of the intraoral scanner and implant library on the trueness of digital impressions in the full-arch implant scan: A comparative in vitro study

ObjectiveTo evaluate the effect of intraoral scanners (IOSs) and implant libraries (ILs) on the trueness of digital impressions for the fabrication of implant-supported full-arch (FA) prostheses. MethodsA stone cast of an edentulous maxilla with 6 implant analogues and cylindrical scanbodies (IPD ProCam®, Matarò, Barcelona, Spain) was probed using a coordinate measuring machine to capture a reference model (RM). The cast was mounted on a mannequin and scanned with 3 different IOSs (iTERO Element 5D Plus®, Align Technologies, San José, CA, USA; IS 3800®, Dexis, Quackertown, PN, USA; and i-700®, Medit, Seoul, South Korea). Ten scans were performed by an experienced operator using each IOS, first capturing only the occlusal surfaces, then the buccal and finally the palatal surfaces (less than 45 s per scan). In each scan, the meshes of the SBs were replaced by the corresponding IL file, with and without increment, to obtain the best correction for the mesh growth. The positions of the SBs in each file were compared with those in the RM, to evaluate the linear and cross distances between them. The final outcome was the trueness of the different IOSs, evaluating the effect of using different ILs on the quality of the impressions. ResultsSignificant differences were found between the different IOS scans and the RM, and among the different IOSs, in the different segments. The correction of the mesh growth through incremental ILs did not affect the final trueness of the IOS scans. ConclusionsDifferent levels of trueness were found among the IOSs evaluated, in the different scan segments, but with the cylindrical SBs used herein, the correction of the mesh growth with incremental ILs did not affect the final quality of the digital impressions. Statement of clinical relevanceThere are still errors with IOS in the FA impressions. IOS have an effect on the quality of the digital impressions, and apparently the library has not, with purely cylindrical SBs: further studies are needed to confirm this aspect.

DIGITAL IMPRESSION VERSUS CONVENTIONAL IMPRESSION FROM THE POINT OF VIEW OF DENTIST PREFERENCES

Nowadays digital impression represents a new breakthrough for dental offices, since more and more dentists use dental scanners. From the point of view of the dentist's preferences, there are not many studies regarding the use of the digital impression in comparison with the conventional impression. (1) Background: The aim of this study was to make a comparison between the digital impression and the classic impression and highlight the advantages and disadvantages of using the two methods, both in terms of the patient and the dentist; (2) Methods: To fulfill the objectives of this study, the Google Forms Platform was used to distribute a questionnaire regarding digital impression and classic impression. The questionnaire included 14 questions with the possibility of choosing only one answer and was addressed to dentists. (3) Results: 42 responses were recorded to the 14 questions contained in the questionnaire; (4) Conclusions: Intraoral scanning dental impression compared to traditional impression has less effect on patient gag effect, breathing difficulties, stress and anxiety, and results in better patient perception and comfort.

Augmented reality assisted intraoral scanning of mandibular arch: A proof-of-concept pilot clinical study

ObjectivesTo investigate whether the scanning time, trueness and number of photos are influenced when augmented reality (AR) heads-up display (HUD) is utilized during the intraoral scan of fully dentate mandibular arches. MethodsA total of 10 patients (6 females and 4 males) were included. The mandibular arch of each patient was scanned twice using an intraoral scanner (Trios4 Pod IOS: 3Shape): one with and one without AR-HUD (ML2; Magic Leap). Further, alginate impression was taken, and the cast was digitized to acquire the reference model for trueness comparison (T310, Medit). The scan time and number of photos were recorded. Trueness was evaluated qualitatively and quantitatively using colored heat maps and RMSE values respectively. t-test was used to evaluate the difference in scan time, trueness, and number of photos between the two groups (α = .05). ResultsAR-assisted IOS resulted in significantly faster scan time (44 s) compared to the time consumed following conventional scan method without AR-HUD (63 s) (P = <0.001). The number of photos was also significantly less with AR-assisted IOS (836) compared to IOS using conventional technique without AR-HUD (1209) P = <0.001. No statistical difference was detected in RMSE between the test groups. ConclusionsIntegration of AR technology with IOS process represents a promising potential to acquire digital impressions with reduced scan acquisition time and reduced images count while simultaneously maintaining the trueness of the acquired scans. Clinical SignificanceAugmented Reality presents an emerging potential in Prosthodontics to acquire digital impressions with decreased number of images and acquisition time.

Color Comparison Between Intraoral Scanner and Spectrophotometer Shade Matching: A Systematic Review and Meta-Analysis.

This systematic review and meta-analysis compared the accuracy of intraoral scanners and spectrophotometers in determining tooth shade. An electronic search of five databases (PubMed, Scopus, Embase, Web of Science, CENTRAL) was conducted on October 19, 2023. A total of 163 studies were identified from the databases, of which 23 articles were eligible for inclusion. In vivo and in vitro quasi-experimental studies were included. After data extraction, a quantitative analysis was performed to determine the accuracy of the intraoral scanner in subgroups using four outcomes: trueness and precision with different measurement locations. A random-effects model was used to pool effect sizes. The pooled proportion with a 95% confidence interval (CI) was used for the effect size measure. Eleven articles were included in the meta-analysis. Trueness with the intraoral scanner was between 0.28 (CI: 0.09-0.60) and 0.38 (CI: 0.24-0.53). Repeatability was between 0.81 (CI: 0.64-0.91) and 0.85 (CI: 0.74-0.92). Trueness showed low, and precision had moderate certainty of evidence. The trueness of shade matching with intraoral scanners is low compared to spectrophotometers, although the precision is considered high and is similar to spectrophotometers. Shade determination with intraoral scanners is not recommended.

Time wears on everyone, but not equally quickly

In 30 patients (average age 38 ± 8 years, 77% male, 23% female) with intra-oral scans made at intake and after 3 years, tooth wear progression was measured. With the aid of GeoMagic to superimpose the scans, the maximum difference in height of 64 surfaces was measured per surface. A large variation was found in progression rates between patients, between various teeth in a single mouth, and between surfaces on a single tooth. Tooth wear progression rates are therefore highly individual and can even be very localized. Treatment must therefore be individualized, with an essential role for measuring tooth wear when deciding on the need for restorative treatment.

Clinical assessment of monolithic zirconia crowns fabricated using an intraoral scanner.

This in vivo study assessed the accuracy of single-tooth monolithic zirconia crowns made using an intraoral scanner (IOS) and computer-aided design/computer-aided manufacturing (CAD/CAM) technology. Thirty patients requiring single posterior crowns were selected. The teeth were prepared with a deep chamfer finish line with a 1-mm extension subgingivally and a 1-mm reduction in all surfaces by one prosthodontist. The gingival margins were retracted using a gingival retraction paste before making impressions using a Trios scanner. All the digital impression files were sent to one laboratory using the dental designer software (3Shape, Copenhagen, Denmark). After completing the milling and sintering processes, the crowns were dyed and glazed. After removing the temporary crown, the qualitative assessment of proximal contacts of definitive monolithic zirconia crowns was performed according to the CDA criteria. Data were analyzed with Friedman's two-way analysis and independent t-test at α=0.05. The difference in axial and total gaps between premolar and molar teeth was not significant; however, the mean marginal gap of molars was higher than that of the premolars (P=0.043). Furthermore, the comparison of the axial, total, and marginal gaps between the upper and lower jaws showed no significant difference (P>0.05). The distribution of occlusal and proximal contacts indicated 60% and 66.7% proper contacts and no contacts in 6.7% and 10% of cases, respectively. Using IOSs could result in accurate monolithic zirconia crowns in terms of adaptation. Also, most occlusal and proximal contacts did not need any adjustments.

Deviation parameters of intraoral scanning with and without artificial markers versus conventional impression of total, partial and congenital nasal defects: A pilot non-randomized clinical trial

PurposeThis pilot clinical trial aimed to investigate accuracy of intra-oral scanning (IOS) with and without artificial reference markers in capturing total, subtotal and congenital nasal defects. Basic proceduresThirteen patients with 3 types of nasal defects were selected and digitally scanned using an IOS with (ScM) and without artificial markers (Sc). Patients were grouped as follows; Group T (total nasal defect), Group P (partial/subtotal nasal defect), Group C (congenital defect). Silicone impressions of the defects were made and poured to get a model that was scanned using a Desktop scanner (Imp). The standard tessellation language (STL) files obtained from IOS were registered and compared to each other using a processing software. RMS, positive and negative average values were used to report deviations between the scans. Kruskal Wallis test was used to study the effect of defect type, while Friedmann was used to study the effect of impression technique. Results were considered significant at P≤.05. Main findingsAll deviation values showed statistically significant differences among the 3 studied nasal defects and among the 3 investigated impression techniques. The smallest deviation values were recorded in Sc-ScM of congenital defects (RMS= 0.13±0.04, +average=0.08±0.01, -average=-0.09±0.02), while the largest deviation values were recorded in IMP-Sc in the total defects (RMS= 0.38±0.05, +average=0.29±0.04, -average=-0.29±0.04). ConclusionsWithin the limitations of this study, it was concluded that the nasal defect type and the use of artificial markers during scanning affect the deviation parameters of the obtained scan. The combined effect of the studied parameters calls for the use of markers in when scanning total nasal defects.

Precision Test of a Multifunctional Scan Body for the Scan and Cross-Mount of an Edentulous Arch: A Pilot Case-Control Study.

The primary goal of this pilot study was to evaluate, via 3D analysis, the scan body precision of an intraoral digital scan utilizing a custom multifunctional scan body compared to that of digitized stone models fabricated from a conventional open tray impression in the fully edentulous maxilla and mandible. The secondary goal of this study was to showcase a method for utilizing the scan body library to generate a fixed fiducial marker for the cross-mount of an edentulous arch. Comparative analysis was performed as a case-control study. A custom scan body was utilized to generate the positions of the titanium bases from the intraoral models and digitized stone models of three maxillary arches (All-On-6, All-On-5, and All-On-4) and two mandibular arches (both All-On-4). The titanium base positions were compared using advanced 3D inspection software. The mean ± SD deviation was 30.38 ± 17.78 μm (95% CI: [14.8 to 45.97 μm]), with mean deviations of 38.73 ± 19.24 μm (95% CI: 16.96 to 60.5 μm) in the maxilla and 17.85 ± 0.92 μm (95% CI: 16.58 to 19.12 μm) in the mandible. The present results were promising, showing that deviations between the intraoral impressions and the digitized stone models fell within established tolerance ranges. Initial studies showed promising results that the digital workflow could be implemented with success similar to the conventional approach. Using the scan body library to generate a fiducial marker successfully demonstrated an efficient method for cross-mounting the edentulous arch.

Accuracy of Intraoral Scanners in Depthof Post Spaces. A Systematic Review

Accuracy of Intraoral Scanners in Depthof Post Spaces. A Systematic Review

Accuracy Analysis of Digital Models from Intraoral Scanners and 3D-Printed Casts in Children and Teenagers.

The aim was to analyze the accuracy of digital models and 3D-printed casts from full-arch digital impressions using two intraoral scanners (iTeroTM and PrimescanTM). A crossover reliability study was designed, scanning children and teenagers with iTeroTM and PrimescanTM. Accuracy was evaluated by measuring intercanine, intermolar, and ipsilateral canine-molar distances intraorally and comparing these measurements with those from plaster casts, digital models obtained with intraoral scanners, and 3D-printed casts. A paired comparison and a general linear model with a one-way repeated measures ANOVA procedure were carried out with a confidence level of 95% (p ≤ 0.05). A total of 51 subjects were analyzed (mean age 12.35 ± 2.57). Statistical differences (p < 0.05) were found in the upper and lower arch regarding accuracy in comparison to intraoral measurements, except for the iTeroTM-printed cast and canine-molar upper right and intercanine lower distances (p > 0.05 for all comparisons). Regarding a comparison between reproduction methods, the plaster cast oversized the intercanine upper distance in comparison with both intraoral scanners' digital models and the PrimescanTM-printed cast (p = 0.001), but there were no differences in the lower arch (p > 0.05 for all comparisons). Intraoral scanners reproduce tooth structures with similar accuracy to conventional methods.

Evaluating the accuracy of CEREC intraoral scanners for inlay restorations: impact of adjacent tooth materials

BackgroundThe accuracy of intraoral scanning is critical for computer-aided design/computer-aided manufacturing workflows in dentistry. However, data regarding the scanning accuracy of various adjacent restorative materials and intraoral scanners are lacking. This in vitro study aimed to evaluate the effect of adjacent restorative material type and CEREC's intraoral scanners on the accuracy of intraoral digital impressions for inlay cavities.MethodsThe artificial tooth was prepared with an occlusal cavity depth of 2 mm, a proximal box width at the gingival floor of 1.5 mm, and an equi-gingival margin extended disto-occlusally at the transition line angle on both the lingual and buccal sides for an inlay restoration. The adjacent teeth were veneered with crowns made of gold and zirconia, and an artificial tooth (resin) was utilized as the control group. The inlay cavity and adjacent teeth (Gold, Zirconia, and resin) were scanned 10 times using Chairside Economical Restoration of Esthetic Ceramics (CEREC) Primescan (PS), Omnicam (OC), and Bluecam (BC). A reference scan was obtained using a laboratory scanner (3-shape E3). Scanning was performed according to the manufacturer's instructions, including powder application for the BC group. Standard tesselation language files were analyzed using a three-dimensional analysis software program. Experimental data were analyzed using a two-way analysis of variance and the Tukey’s post-hoc comparison test.ResultsThe restorative materials of the adjacent teeth significantly affected the accuracy of the intraoral digital impressions (p < .05). The zirconia group exhibited the highest trueness deviation, followed by the resin and gold groups, with each demonstrating a statistically significant difference (p < .05). The resin group demonstrated the highest maximum positive deviation and deviation in precision. Gold exhibited the lowest average deviation value for trueness compared with those of the other adjacent restorative materials. Intraoral scanner type significantly influenced the trueness and precision of the scan data (p < .05). The average deviation of trueness according to the intraoral scanner type increased in the following order: BC > PS > OC. The average deviation in precision increased in the following order: PS>OC>BC (p < .05).ConclusionThe restorative materials of the adjacent tooth and the type of intraoral scanner affect the accuracy of the intraoral digital impression. The trueness of the digital images of the BC group, obtained by spraying the powder, was comparable to that of the PS group. Among the adjacent restorative materials, zirconia exhibited the lowest trueness. In contrast, PS demonstrated the highest precision among the intraoral scanners, while resin displayed the lowest precision among the adjacent restorative materials.

Accuracy of intraoral scanners based on jaw curve and inter-implant distance

Background: In digital dentistry, the intraoral scanner (IOS) is the primary data-collecting device. The data must be accurate to prevent undesirable stresses and technological difficulties resulting from prosthetic misfits. The span length of restorations influences the accuracy of IOS impressions. Purpose: This research aimed to compare the accuracy of virtual models scanned by different IOSs to determine whether jaw curvature and inter-implant distance affect accuracy. Methods: Four mandibular edentulous models were prepared by replacing the site of the missing tooth with an implant. The prepared holes were drilled at 7mm, 14mm, 21mm, and 28mm. Five scans for each model were taken with a desktop laboratory scanner as a reference model and with Trios3Shape and 3Disc Heron IOSs to evaluate trueness and precision (T&amp;P). The scans were saved as standard triangulation language files and statistically analyzed at a level of significance (P ≤ 0.05). Results: There was a significant difference between the IOSs in inter-implant distances (P &lt; 0.05). The greatest distortion was reported in the 21mm and 28mm groups for both scanners (P ≤ 0.05), while the lowest distortion was observed in the 7mm and 14mm groups for the Trios3Shape scanner. Conclusion: Jaw curvature and inter-implant distance impacted the accuracy of the IOS. Distortion and reduced reproducibility of T&amp;P increased with jaw curve and inter-implant distance. The Trios3Shape IOS showed maximum accuracy at 7mm and 14mm inter-implant distances, while the 3Disc Heron IOS produced significant distortion of trueness at 21mm and 28mm inter-implant distances.

Effect of cut-out rescanning protocol on the accuracy of digital impressions in convergent implants positioned at varying depths: An in vitro study

BackgroundThis study aimed to assess the effect of the "cut-out rescan" strategy on the accuracy of intraoral digital scans from 25° convergent implants positioned at two distinct depths. Material and methodsTwo customized models were fabricated, each designated to receive two posterior converged implant fixtures: one at a depth of 1 mm and the other at a depth of 4 mm. Initially, the models were scanned as reference casts using a lab scanner. The test group was involved in scanning the 1-mm and 4-mm implant models using an intraoral scanner in the following order: (1) scanning the 1-mm (T1; n = 10) and (2) 4-mm (T4; n = 10) implant groups with scan bodies connected to both fixtures in each model; (3) cut-out rescan (COR) in the 1-mm (COR1; n = 10) and (4) 4-mm (COR4; n = 10) models, leading to 40 digital files in standard tessellation language format. The mean absolute deviation (MAD), in terms of trueness and precision, between the experimental and control scans was assessed through the alignment of their respective datasets using three-dimensional analysis software. Two-way analysis of variance (ANOVA) and Levene's tests were used to analyze the data. ResultsThe COR4 group exhibited the highest MAD, indicative of both trueness and precision (Mean ±SD: 55.659 ±34.802). In contrast, the T1 group demonstrated the lowest MAD (Mean ±SD: 43.225 ±19.237). However, the ANOVA analysis showed no significant influence of depth (P = 0.506) or type of scan (P = 0.442) on the MAD. Precision also did not differ significantly across groups (P = 0.071). ConclusionsThe cut-out rescan approach demonstrated an accuracy comparable to that of the one-time scan method. Clinical significanceDigital intraoral scanning provides clinicians with a range of tools to navigate challenging conditions in which conventional methods may prove difficult, such as cases involving angled adjacent implants. In these scenarios, the cut-out rescan tool serves as a valuable resource, aiding clinicians in overcoming the challenges associated with impression-making owing to the convergence of placed implants.