International Journal of Computerized Dentistry, Pre-Print

Aim: To report on a novel digital superimposition workflow that enables measuring the supra-crestal peri-implant soft tissue dimensions all along implant treatment and afterwards. Materials and Methods: A preoperative CBCT and intra-oral scans (IOS) are successively taken before surgery, at the end of the healing period, at prosthesis delivery, and over time; they are digitally superposed on a dedicated software. Then, the stereolithography files (STL) of the healing abutment, of the prosthetic abutment and the crown are successively merged into the superposition set of IOSs. Result: The workflow protocol of merging successively the STL of each item into the superposition set of IOSs enables capturing the dimensions of the height and width of the supra-crestal soft tissues, at every level of the healing abutment, the prosthetic abutment and the crown. In addition, it allows measuring the vertical distance that the crown exerts pressure on the gingiva and the thickness of the papillae at every level of the abutment. Conclusion: This novel digital superimposition workflow provides a straightforward method of measuring the vertical and horizontal dimensions of the supra-crestal peri-implant soft tissues, including the papillae, at each stage of the implant treatment process. It allows investigating a certain number of soft tissue variables that were previously inaccessible to clinical research. It should help enhancing our comprehension of the peri-implant soft tissue dynamics. Keywords: CBCT, clinical research, digital merging, gingival height, gingival width, intra-oral scan, papilla, peri-implant soft tissues

Purpose: Is to investigate how integrating intraoral scanners in routine oral diagnosis affects patient-clinician communication, patient perceptions and preferences, offering valuable insights into the patient experience and utility of intraoral scanners in clinical practice. Materials and Methods: A restorative dentistry specialist conducted intraoral examination on 300 patients, initially using conventional techniques and X-rays, followed by a 3D scanner (ITero®element, Align Technologies, San Jose, California, USA). The patient's existing oral issues and treatment plan were initially expressed verbally, and then repeated using a 3D scan. Subsequently, the patients were requested to respond to an 11-question survey, aimed at assessing both modes of examination and communication. Statistical analysis using SPSS v.22 software included employing the Wilcoxon test to compare the patients’ experiences on the same topic before and after the examination with the intraoral scanners, considering significance at p<0.05. Results: Majority (38%) of participants aged 25-35. Gender split was 52% female, 48% male. Patients statistically found it more comprehensible to visualize existing oral issues through 3D scans than through verbal explanation (p=0.000). Also, patients understood oral hygiene recommendations better when explained via 3D scanning by dentists (p=,000). The vast majority of the participants (94%) indicated that being examined with an intraoral scanner motivated them for treatment, while 6% remained undecided. A hundred percent of the participants stated that 3D scanners should be included in the routine oral examination. Conclusion: Intraoral 3D scans enhance patient understanding and communication during oral examination and participants show high preference. However, more research needed to replace conventional diagnostic methods. Keywords: 3D imaging, digital imaging, intraoral scanners, oral diagnosis, oral examination

Objective: To investigate the application of dynamic navigation guidance technology in different implantation scenarios, and to provide a scientific basis for the innovation and advancement of implantation techniques. Methods: Fifteen cases of patients with malocclusions admitted between January 2021 and February 2023 were selected as the study subjects. All patients underwent dynamic navigation-guided oral implantation interventions. CBCT scans were taken after implantation surgery to record deviations of implantation points, including implantation point deviation, endpoint deviation, and angle deviation. Results: Dynamic navigation guidance effectively improves the reliability and stability of implantation in oral implant patients. CBCT effectively evaluated the state of the patient's periodontal implant, analyzed the state of the patient's lesion area, and improved the quality of implant intervention through CBCT guidance. The implantation point deviation was (0.407±0.193) mm, the endpoint deviation was (0.492±0.201) mm, and the implant angle deviation was (2.162±0.283)°. There was no significant difference in implantation point deviation in the anterior and posterior parts of the upper and lower jaws after intervention (P>0.05). However, there were significant differences in endpoint deviation and implant angle deviation among the anterior and posterior parts of the upper and lower jaws (P<0.05). Conclusion: Dynamic navigation guidance effectively improves the reliability and stability of implantation in oral implant patients. However, there is relatively greater endpoint deviation and implant angle deviation in the posterior part of the upper jaw. Keywords: deviation, Dynamic navigation guidance, oral implantation, Oral Implantation, Stomatology

Aim: The current study aimed to compare the responses and satisfaction reported by users with varying levels of experience when using different types of computer-aided design (CAD) software programs to design crowns. Materials and methods: A questionnaire was used to evaluate user responses to five domains (software visibility, 3Dscanned data preparation, crown design and adjustment, finish line registration, and overall experience) of various CAD software programs. The study included 50 undergraduate dental students (inexperienced group) and 50 dentists or dental technicians from two hospitals (experienced group). The participants used four different CAD software programs (Meshmixer, Exocad, BlueSkyPlan, and Dentbird) to design crowns and recorded the features using the questionnaire. Statistical analyses included one-way and two-way analysis of variance (ANOVA) tests to compare scores and verify the interaction between user response and experience. Result: User evaluation scores in the domains of software visibility and 3D-scanned data preparation varied between software programs (P < 0.001), with Exocad being favored by the experienced group. When evaluating crown design and finish line registration, Dentbird and Exocad scored significantly higher than the other software in both groups as they offered automation of the process using deep learning (P < 0.001). Two-way ANOVA showed that prior experience of using CAD significantly affected the users’ responses to all queries (P < 0.001). Conclusion: User response and satisfaction varied with the type of CAD software used to design dental prostheses, with prior experience of using CAD playing a significant role. Automation of design functions can enhance user satisfaction with the software. Keywords: CAD, deep learning, experience, prosthesis, satisfaction

Aim: Condylar hyperplasia (CH) is a progressive and deforming disease that modifies anatomy of the temporomandibular joint (TMJ) structures. This study aims to correlate the metabolic bone activity of the condyle measured by SPECT with the volumetry anatomic information from the condyle, fossa and joint space provided by CT images, in patients with CH in active and inactive forms. Materials and methods: A cross-sectional comparative study was performed with a set of 116 images from healthy and diagnosed CH patients to compare volumetric measures of the TMJ. Images were acquired through a bone tissue mask using a three-dimensional DICOM reconstruction for SPECT/CT and CBCT images and the Threshold option for segmentation with standardized values for each tissue on the HU scale. Results: there are differences (p<0.01), with greater condylar volume on the affected side in patients with active CH compared to passive CH. The volume of the glenoid cavity shows no differences in either form of CH (p>0.05), however, there were differences for the volume of the joint space on the affected right side of hemimandibular elongation (HE) in the active form. The volume of the mandibular condyle on the affected side in CH cases were larger in HE cases in active and inactive form (p<0.01) compared to healthy patients. Similar results were presented for the glenoid cavity and joint space. Conclusions: Volumetric anatomical evaluation of TMJ structures, as well as information on condylar metabolic activity, can be obtained from SPECT/CT. The study shows a greater condylar volume on the affected side of the CH compared to the contralateral side, but there are more significant differences in the active than in the inactive form. Keywords: CBCT, Condylar hyperplasia, Condylar volume, SPECT/CT, Temporomandibular Joint, tomographic segmentation

Aim: The aim of this scoping review was to identify the scientific evidence related to the utilization of Optical See- Through Head-Mounted Display (OST-HMD) in dentistry, and to determine future research needs. Methods: The research question was formulated using the "Population" (P), "Concept" (Cpt), and "Context" (Cxt) framework for scoping reviews. Existing literature was designated as P, OST-HMD as Cpt, and Dentistry as Cxt. An electronic search was conducted in PubMed, Embase, Web of Science, and CENTRAL. Two authors independently screened titles and abstracts and performed the full-text analysis. Results: The search identified 286 titles after removing duplicates. Nine studies, involving 138 participants and 1760 performed tests were included in this scoping review. Seven of the articles were preclinical studies, one was a survey, and one was a clinical trial. The included manuscripts covered various dental fields: three studies in orthodontics, two in oral surgery, two in conservative dentistry, one in general dentistry, and the remaining one in prosthodontics. Five articles focused on educational purposes. Two brands of OST-HMD were used: in eight studies HoloLens Microsoft was used, while Google Glass was utilized in one article. Conclusions: The overall number of included studies was low; therefore, the available data from this review cannot yet support an evidence-based recommendation for the clinical use of OST-HMDs. However, the existing preclinical data indicate a significant capacity for clinical and educational implementation. Further adoption of these devices will facilitate more reliable and objective quality and performance assessments, as well as more direct comparisons with conventional workflows. More clinical studies must be conducted to substantiate the potential benefits and reliability for patients and clinicians. Keywords: augmented reality, dental education, digital dentistry, mixed reality, scoping review, virtual reality

Aim: Malocclusion has emerged as a burgeoning global public health concern. Individuals with an anterior crossbite face an elevated risk of exhibiting characteristics such as a concave facial profile, negative overjet, and poor masticatory efficiency. In response to this issue, we proposed a convolutional neural network (CNN)-based model designed for the automated detection and classification of intraoral images and videos. Materials and Methods: A total of 1865 intraoral images were included in this study, 1493 (80%) of which were allocated for training and 372 (20%) for testing the CNN. Additionally, we tested the models on 10 videos, spanning a cumulative duration of 124 seconds. To assess the performance of our predictions, metrics including accuracy, sensitivity, specificity, precision, F1-score, area under the precision-recall (AUPR) curve, and area under the receiver operating characteristic (ROC) curve (AUC) were employed. Results: The trained model exhibited commendable classification performance, achieving an accuracy of 0.965 and an AUC of 0.986. Moreover, it demonstrated superior specificity (0.992 vs. 0.978 and 0.956, P < 0.05) in comparison to assessments by two orthodontists. Conversely, the CNN model displayed diminished sensitivity (0.89 vs. 0.96 and 0.92, P < 0.05) relative to the orthodontists. Notably, the CNN model accomplished a perfect classification rate, successfully identifying 100% of the videos in the test set. Conclusion: The deep learning (DL) model exhibited remarkable classification accuracy in identifying anterior crossbite through both intraoral images and videos. This proficiency holds the potential to expedite the detection of severe malocclusions, facilitating timely classification for appropriate treatment and, consequently, mitigating the risk of complications. Keywords: computer aided diagnosis, convolutional neural networks, deep learning, image detection, malocclusion, oral diagnosis

Aim: The purpose of this study is to develop software at a low cost that enables the detection of tooth colors by capturing photographs using various devices, and to compare its effectiveness with existing expensive methods. Material and Methods: A total of 60 anterior central incisor teeth from 30 individuals were included in the study. The CIELAB values (L,a,b) of each tooth were measured using a spectrophotometer, which is considered the gold standard. Subsequently, photographs of the teeth were taken using four different smartphones (iPhone- Xiaomi) and one digital camera (Canon). These images were then subjected to image processing techniques and compared with measurements obtained through computer-based analysis in order to assess the correlation. Data with three or more groups, the Kruskal-Wallis H test was utilized, and multiple comparisons were conducted using the Dunn test. A significance level of p<0.05 was considered. Results: Upon examining the results of multiple comparisons, a statistically significant difference was observed (p<0.001) between the DeltaE values obtained from the camera of the iPhone and those obtained from the Canon DSLR and Xiaomi cameras. The iPhone cameras yielded result values ranging from 2.68 to 2.90 for DeltaE. Conclusions: It is reported that color determination methods based on image processing of photographs taken with iPhone mobile phones could potentially gain an advantageous position in routine clinical practice, as compared to spectrophotometry. Keywords: Color Detecting, Image Processing, Shade Matching, Smartphones, Spectrophotometer

Aim: The aim of this study was to evaluate the physical-mechanical behavior of the occlusal veneers when subjected to thermomechanical cycling. Materials and Methods: Sixty specimens were divided into 04 groups (n=15 per group), according with the different restorative materials and thicknesses: material – lithium dissilicate LD (IPS e.max CAD, Ivoclar Vivadent) and nano- ceramic-resins NCR (ESPE Lava Ultimate, 3M); thickness - 0.6 and 1.2mm. The occlusal veneers were bonded over human flattened fresh extracted molars with dual-polymerizing luting agent (Variolink N, Ivoclar Vivadent and RelyX Ultimate 3M) using the respective adhesive system following the selective-etch technique (self-etch in dentin and total etch in enamel). The resin cement was light cured for 40 seconds each face, using a LED light cure equipment (BlueStar II, Microdont, 1100 mW/cm2). The response variables consisted of veneer survival rates (crack formation, catastrophic cracks and debonding) when subjected to thermal cycling from 5° to 55° C and simultaneous mechanical cycling performed at load intensities of 100, 200, 300, 400 and 450N for 20,000 cycles each. Result: Data were submitted to the Kruskall Wallis test and Pairwise Comparison, adopting a significance level of 5%. NCRs presented a lower incidence of failures (p<0.05) when compared to LD. According to thickness factor, 1.2mm thick occlusal veneers withstand higher cycling loads. Conclusion: NCR occlusal veneers with 1.2mm thickness presented superior physical-mechanical behavior than lithium disilicate and 0.6mm restorations. Keywords: CAD/CAM, Ceramics, Digital Dentistry, Minimally Invasive Dentistry, Occlusal veneers, Resin Composite

Objectives: To evaluate the peri-implant marginal bone loss (MBL) and prosthodontic complications of maxillary screw-retained implant prosthesis fabricated from digital versus conventional full- arch implant impression. Material and Methods: 28 participants with edentulous maxillary arches were randomly selected and enrolled in two equal groups; Group I conventional impression group (CIG) and Group II Digital impression group (DIG). All patients were rehabilitated with maxillary screwretained implant prosthesis retained by 6 implants. Peri-implant MBL and prosthodontic complications and were registered at 6, 12, and 24 months (m). Data was collected and statistically analyzed. Results: Regarding the effect of time, there was a statistically significant increase in MBL at 6, 12 and 24 m follow-up periods (P<.001). As for the effect of groups, there was no statistically significant difference in MBL between CIG and DIG at 6, 12 and 24 m where P value was 0.083, 0.087 and 0.133 respectively. Prosthetic complications were recorded 19 times in the conventional group and 12 times in the digital group with no significant difference between both groups (P=.303). Conclusion: Digital full -arch implant impression is a reliable impression technique and may represent an alternative to conventional impression technique in the fabrication of maxillary screw-retained implant prosthesis. Keywords: conventional implant impression, digital implant impression, full- arch implant impression, marginal bone loss, maxillary screw-retained prosthesis, prosthodontic complications

Objective: The aim of this study was to examine the color stability of laminate veneer restorations restored with CAD/CAM material applied to bleached teeth. Material and methods: In this study, 80 upper central teeth extracted because of periodontal, orthodontic or trauma problems were used. The teeth were embedded in acrylic blocks and divided into 8 groups (n=10). Groups A, B, C and D were bleached with vital bleaching agent before preparation, and teeth were prepared for laminate veneer restorations. Groups E, F, G and H were prepared without bleaching. Groups A and E were restored with A1 GC LiSi İnitial HT blocks, Groups B and F were restored with A1 GC LiSi İnitial LT blocks, Groups C and G were restored with A1 IPS Emax CAD HT blocks, Groups D and H were restored with A1 IPS Emax CAD LT blocks. All restorations were adhesively cemented and aged for 2 and 5 years with thermal cycle. Color measurements of the restorations at the beginning, after 2 and 5 years of aging were measured with a spectrophotometer. Results:All bleached groups had more color changes than the unbleached groups. The least color change after 2 years of aging was observed in GC LiSi Initial LT (ΔE00=0.81) and IPS Emax CAD LT (ΔE00=0.81) materials which were used on unbleached teeth and the most color change was observed in GC Initial LiSi HT (ΔE00=0.93) and IPS Emax CAD HT material (ΔE00=0.92) which were used on bleached teeth. After 5 years of aging, the least color change was observed in IPS Emax CAD LT (ΔE00=0.83) and GC LiSi Initial LT material (ΔE00=0.84) which were used on unbleached and the highest color change was observed in GC Initial LiSi HT (ΔE00=0.96) and IPS Emax CAD HT material (ΔE00=0.94) which were used on bleached teeth. Conclusion: Bleaching and translucency affect the color stability. No difference was detected between the color changes of GC LiSi Initial and IPS Emax CAD materials. The increase in aging time increased the color changes of all materials. Clinical Significance: Bleaching and laminate veneer restorations may be preferred in many patients. For this reason, the long-term color change of laminate veneer restorations applied to bleached teeth is clinically very important. This study aimed to evaluate the effect of tooth bleaching on the long-term color change of laminate veneer restorations produced with different translucent CAD/CAM materials. Keywords: Bleaching, CAD/CAM, Color, Laminate veneer, Spectrophotometer

Aim: The aim of this in vitro study was to investigate the influence of scan paths on the accuracy (trueness and precision) of intra-oral scanning of an implant impression on an edentulous patient. Material and methods: An epoxy resin maxillary model was made with 6 bone level implants (NobelParallel Conical Connection RP, NobelBiocare®). The implants were placed at the spot of the first incisor, the canine and the first molar. The trans gingival component (Multi-unit, NobelBiocare®) was screwed onto the implants. The scanbodies (IO 2C-A, Elos Accurate®) were then screwed onto the multi-units. The model was run through a coordinate measurement machine to obtain a control cast. Then, five different scanning paths, respectively the zigzag technique (ZZT), the zigzag technique with palatal (ZZTP), the wrap technique (WT), the wrap technique with palatal (WTP), and the big zigzag technique (BZZT), were applied by a single operator. Finally, each scan was compared to the control model. Results were assessed by one-way ANOVA and linear mixed effects models at P<0.05. Results: The study showed that scan paths ZZT and ZZTP had significantly lower absolute positioning errors and residual mean square errors than the others (P<0.0001). For distances between consecutive implant axes and for absolute vertical errors, their superiority was borderline (P<0.10). Overall, techniques ZZT and ZZTP were equally performant and proved to be the most accurate. Conclusions: This in vitro experimental study demonstrates that the scan path can have an influence on the accuracy of the optical impression for full arch rehabilitation on implants. Keywords: Accuracy, Dental implants, Digital impression, Edentulous, Intra-oral scanner, Scan path

Objectives: Mandibular single-implant overdenture is a well-established treatment modality for the management of completely edentulous patients. The use of CAD/CAM printing technology to fabricate complete dentures and overdentures is burgeoning. The trial aimed to clinically evaluate 3D-printed single-implant overdentures and compare outcomes to those of overdentures manufactured using conventional techniques. Materials and Methods: A randomized clinical trial (RCT) was designed. Twenty-eight participants were randomly allocated into two equal groups. Participants in the control group received conventionally manufactured single-implant overdentures, while participants in the printed group received digital light processing (DLP) printed single-implant overdentures. An evaluation was conducted to assess the rates of implant survival and success, as well as overdenture survival and success, along with the measurement of maximum biting force (MBF) over a one-year follow-up period. Data was collected and subjected to statistical analysis. Statistical significance was determined using a two-sided p-value with a threshold of less than 0.05. Results: The printed denture group had higher implant survival (100%) and success rates (92.8%) compared to the conventional denture group (85.7% survival, 85.7% success). Overdenture survival and success rates were 100% in the printed group and 78.6% in the conventional group. Both groups showed a significant increase in maximum biting force (MBF) at 3, 6, and 12 months of follow-up (P<0.001). The printed group demonstrated a statistically significant improvement in MBF compared to the conventional group (P<0.001). Conclusions: 3D-printed mandibular single-implant overdentures may represent an alternative to conventionally fabricated ones. Keywords: 3D printing, Biting Force, Denture Survival, Implant, Implant Survival, Overdenture

Medical imaging technology has greatly improved over the last 40 years. A good example of this is the improved 3D reconstruction capabilities of CTs, which enable photorealistic reconstructions. This technological advancement has also taken place in the computer industry, and the development of modern graphics cards has fueled progress in video games. In art, many of the techniques used to improve three-dimensionality have been known for centuries. At first sight, these fields seem unrelated, but there is actually considerable confluence. This paper focuses on three areas: fine arts, video games and radiology. The art section illustrates different drawing techniques used to create three-dimensionality. The section on video games shows the development of video games from the 1980s to the present day. Finally, the medical imaging section focuses on the first 3D radiography reconstructions in the 1980s and the improvements to the present day. Contemporary video games and 3D reconstructions of CTs enable photorealistic impressions of 3D anatomical structures. An important factor is shadow casting and light, which has been known in fine arts for centuries. The effect on the observer of photorealistic 3D reconstructions in video games and in medical imaging can be largely explained by the knowledge of 3D techniques in drawings and paintings. Keywords: 3D-reconstruction, Anatomy, Fine arts, Radiology, Video Games

Objective: To compare the accuracies among three oral implant surgical techniques: freehand (FH), static computer-assisted implant surgery (sCAIS), and robotic computer-assisted implant surgery (rCAIS). Methods: The polyurethane and bovine femur implant models were fabricated, and 126 and 96 implant sites were designed on them. The implant sites were divided into three groups: FH, sCAIS, and rCAIS, according to the implantation method. The deviation between the actual implant position and the planned position was analyzed and compared by cone beam computed tomography. Results: In the polyurethane model test, the entry deviation, entry-level deviation, apical deviation, apical level deviation, and angle deviation in sCAIS and rCAIS groups were significantly reduced compared with those in the FH group (P<0.05). No significant differences were observed in all kinds of deviations between the sCAIS and rCAIS groups (P>0.05). In the bovine femur model test, the entry deviation, entry-level deviation, apical deviation, apical level deviation, and angle deviation in both sCAIS and rCAIS groups were significantly reduced compared with those in the FH group (P<0.05). No significant differences were observed in all kinds of deviations between the sCAIS and rCAIS groups (P>0.05). Conclusion: This in vitro study shows that the rCAIS technique is superior to the freehand, but has the same accuracy as the sCAIS. Keywords: robotic computer-assisted implant surgery, accuracy, dental implants, freehand, static computer-assisted implant surgery

Aim: To assess the agreement rates of dental records derived from intraoral scan-based digital three-dimensional models (3DM) and 3DM + panoramic radiographs (3DM+PAN-X) compared to clinical findings. Materials and Methods: Based on the 3DM/3DM+PAN-X of 50 patients undergoing supportive periodontal therapy (SPT), ten remote raters (inexperienced in using IOS or 3DM) assessed for each site of the dental scheme (32 sites) whether a tooth was missing (M), filled (F), restoration- and caries-free (H), replaced by an implant (I) or decayed (D). Remote records were compared to the clinical reference record of each patient at tooth-level. The clinical records were assessed by an experienced dentist who supplemented the clinical findings with information from available radiographs and the patient records to define the clinical reference record. Results: The agreement-rates for 3DM/3DM+PAN-X at tooth-level are: M: 93%/94%, F: 84%/88%, H: 92%/92%, I: 65%/96%, D: 29%/29%. The overall agreement-rate is 88% for the 3DM-based dental records (14093 of 16000 entries true) and 91% for 3DM+PAN-X (14499 of 16000 entries true). Using 3DM for dental record assessment, posterior teeth had higher odds of correct findings compared to anterior teeth (upper jaw OR=2.34, lower jaw OR=1.27). Conclusions: The remote detection of healthy, missing and filled teeth and implants by raters inexperienced in using IOS or 3DM shows a high agreement-rate with the clinical findings. The additional evaluation of PAN-X increased the agreement-rate significantly for implants. Thus, the remote assessment of dental records using 3DM+PAN-X has a high accuracy when applied in SPT-patients with low caries activity. Keywords: dental record remote assessment, digital dentistry, digital imaging, full-arch impression, intraoral scanners, supportive periodontal therapy

Aim: To develop a periodontal disease prediction software and a patient-based gingival recession simulator for clinical practice aiming at improving oral hygiene motivation of patients with periodontal problems. Materials and Methods: Periodontal Disease Prediction (PDP) software has three components: a) Data Loading Window (DLW) b) Three-Dimensional Mouth Model (3DM) and c) Periodontal Attachment Loss Indicator (PLI). Demographic and clinical examinations of 1057 volunteers were recorded to DLW. An unsupervised machine learning K means clustering analysis was used to categorize the data obtained from the study population and identified the periodontal risk groups. An intraoral scanner was utilized to capture direct optical intraoral data of a patient and transferred to the 3DM. The intraoral model went under two algorithm steps for obtaining a recessed model. First, gingival curves separating gingiva and tooth were extracted using a Dijkstra’s algorithm. Limit curves determining boundaries of recessed regions in the intraoral model were then obtained using gingival curves. Results: Study participants were divided into three different periodontal risk categories defined as low risk (n=462), medium risk (n=336) and high risk (n=259). Gingival curves separating gingiva and tooth were extracted, and recessed models were obtained given inputs for the expected amount of recession via the proposed method. Furthermore, the user can also demonstrate the gingival recession gradually via the slider method attached to the developed programme. Conclusions: User-friendly computer-based periodontal risk estimation tool and patient-specific gingival recession simulator was developed and presented for clinical usage of dentists. Keywords: Computer-aided design, Dijkstra's algorithm, Gingival recession, Oral hygiene motivation, Periodontitis

Aim: The aim is to record the surface roughness of monolithic chairside CAD/CAM zirconia materials to evaluate the influence of milling speed on the ability to achieve a clinically desirable surface. The null hypothesis is that there is no significant difference in the surface roughness of different zirconia materials based on the speed of subtractive milling. Materials and Methods: All test samples were milled from four different monolithic CAD/CAM zirconia blocks including CEREC Zirconia (Dentsply Sirona), CEREC Zirconia+ (Dentsply Sirona), CEREC MTL Zirconia (Dentsply Sirona), and Katana Zirconia (Kuraray Noritake). Four different dry milling speeds, Super Fast/Good, Super Fast/Very Good, Fast, and Fine were used to dry mill the specimens in a CEREC Primemill (Dentsply Sirona). A 3D measuring laser microscope (OLS4100 LEXT by Olympus) was used to measure surface roughness. Results: An Analysis of Variance (ANOVA) was used to analyze the surface roughness data for each material and milling speed. There was a significant difference for milling speed (p < 0.05) but not between zirconia materials (p > 0.05). Conclusion: Based on the limitations of this study, the milling speed influenced the surface roughness of dry milled and sintered zirconia with slower speeds resulting in smoother surfaces. The largest improvement in surface roughness occurred between Super Fast and Fast milling with a smaller incremental improvement in surface roughness with Fine milling for the Primemill. All recorded surface roughness values are within the expected range of values to be able to efficiently hand polish a clinically acceptable surface finish. Keywords: CAD/CAM, CEREC, mill speed, Surface Roughness, zirconia

Aim: To evaluate the failure rate of palatal computer-guided miniscrews, placed in paramedian and parapalatal regions for orthodontic purposes. In addition, to investigate the presence of a learning curve using computer guided miniscrew insertion, and to evaluate the peri-implant soft tissues response at 2-, 6- and 12- month follow-ups. Materials and Methods: 202 palatal computer-guided miniscrews were inserted in 78 subjects for orthodontic purposes. A surgical guide was designed after planning the appropriate insertion sites on three-dimensional images created by the fusion of cone-beam computed tomography (CBCT) and digital dental model images. The devices were disassembled monthly to perform the percussion test and to evaluate the mobility of each miniscrew. To determine the presence of a learning curve, the time of miniscrew failures and the number of surgeries were evaluated. Bleeding on probing (BOP) and probing pocket depth (PPD) were recorded for each miniscrew, at 2- (T0), 6- (T1), and 12-month follow ups (T2). Results: An immediate failure rate of 4.95%, due to lack of primary stability immediately following miniscrew insertion, was recorded, with statistically significant higher failure rate of parapalatal miniscrews (P= 0.00). Miniscrew failure occurred at random time, with an absence of a learning curve. The BOP (mean: 3.13%) and PPD (mean: 1.68mm) measurements remained stable over time. Conclusions: Computer-guided miniscrew insertion in the palatal vault showed a low failure rate without a determined learning curve to obtain predictable results and with long-term stability of peri-implant soft tissues indexes. Keywords: computer-guided surgery, failure rate, Orthodontics, skeletal anchorage, TADs

Aim: To evaluate the accuracy and reproducibility of real and virtual occlusal contact points in implant-supported, fixed complete dentures. Materials and methods: The study included 19 participants using mandibular interim complete-arch fixed prosthesis supported by 3 or 4 implants as opposed to conventional removable complete dentures. At installation, an examiner installed the prostheses and verified the occlusal contact points through 2 methods: recording the real contact points with carbon paper (RC) followed by occlusal photography and intraoral scanning (VC) to record the virtual contact points to obtain a screen print of the software. Then, the two images were randomized to determine the order to be inserted into Microsoft PowerPoint for blind and paired evaluation. The independent variables consisted of the distribution of occlusal contacts points (qualification through pre-defined scores based on the position of the contact points on the surfaces of the teeth) and the reproducibility of the methods by verifying the number of occlusal points. For this, a descriptive analysis was used to evaluate the distribution of occlusal contacts points and the Wilcoxon test for the reproducibility of the occlusal contact points between the methods (p<0.05). Results: The methods had 100% and 73.6% real and virtual occlusal contact points, respectively, which is considered clinically excellent. There was no significant difference regarding the reproducibility of the methods by the number of occlusal contact points (RC: x̅13.32; VC: x̅13.68; p=0.715). Conclusion: The use of the tested intraoral scanner can be an easy and fast tool for studying and mapping the occlusion, and storing data for future treatment, with the conventional method being the preferred method for performing the occlusal adjustment. Keywords: implant-fixed dental prosthesis, dental occlusion, edentulous, jaw, Occlusal adjustment, three-dimensional imaging

Learning tooth preparation techniques and the finesse required is an important part of preclinical dental education. Being able to practice surgical skills without loss of Frasaco® teeth while being provided with performance analysis data is a boon to students and educators. We investigated the combination of haptics-enhanced virtual reality (Simodont®) and conventional phantom head practice in a preclinical dental course, evaluating the students’ performances and perceptions. Forty students were randomized into two groups: Group One began within a VR-haptic setting while Group Two worked with Frasaco® teeth. Halfway through the course the scenarios were switched. A crown preparation test on Frasaco® teeth was conducted at the end of the course. Students’ performances and satisfaction were assessed anonymously. Analysis of the students’ performances included clinical metrics (occlusal and axial reduction, convergence angle, damage to adjacent teeth). The perceived usefulness of VR-haptic and phantom head simulations was assessed. In Group One, the tooth preparation metrics were more in line with the requested parameters compared to Group Two. All students ranked VR-haptics highly regarding manual dexterity improvement. In conclusion, this study shows that by combining VR-haptics with conventional dental procedures, it is possible to improve important preparation metrics in fixed prosthodontics tooth preparation. Keywords: dental training, manual dexterity, practice-based learning and improvement, survey, VR-haptic simulation

Aim: The adjustment and transfer of a stable occlusion can be a major challenge in prosthetic rehabilitations. The aim of this study was to assess a non-invasive treatment option for complex prosthetic rehabilitations and occlusal analyses using 3D-printed restorations clinically. Materials and Methods: Eleven patients received a partial or complete rehabilitation with the aid of 3D-printed restorations (n=171). After 12 months of clinical service, all restorations were analyzed using the United States Public Health Service (USPHS) criteria. Results: The 12-month clinical data revealed that 3D-printed restorations showed a survival rate of 84.4%. Complications occurred mostly regarding the anatomical form (7%) or marginal integrity (6AC%) and were consequently rated “Charlie” or “Delta.” Color stability and color match of 3D-printed restorations were rated “Alpha” in 83% and 73%, respectively, of all restorations. Marginal inflammation was rated “Alpha” in 89% of all restorations. An excellent surface texture and no secondary caries or postoperative sensitivities (100%) were observed. Conclusions: 3D-printed restorations might be an alternative treatment option for initiating complex prosthetic rehabilitations. Technical complications rarely occurred. Biological complications did not occur at all. The color stability showed promising results after 12 months of clinical service. However, the results should be interpreted with caution. Long-term results with a high number of restorations should be awaited. Keywords: 3D-printing, additive manufacturing, CAD/CAM, color stability, in vivo, wear behavior

Aim: To evaluate and compare the marginal adaptation and fracture resistance of resin matrix ceramic crowns fabricated using 3-dimensional (3D) printing and computer aided design/computer aided manufacturing (CAD/CAM) milling technology. Materials and Methods: Thirty extracted human maxillary first premolars were prepared to receive crown restorations and grouped into 3 groups according to 3 different crown materials (n = 10): VE: teeth restored with milled Vita Enamic, CS: teeth restored with milled Cerasmart 270 and VSC: teeth restored with 3D-printed VarseoSmile Crown Plus. Marginal analysis was performed with the aid of a digital microscope at (230x) magnification, both before and after cementation with self-adhesive resin cement and analyzed with Image J analysis software. The fracture loads for each sample were then recorded using a universal testing machine in a single load-to-failure test up until the crowns failed. Results: The lowest marginal gap values were recorded for VSC before (8.03 μm) and after (15.07 μm) cementation with significant difference compared to the other crown materials (p <0.05), while the differences between the milled groups were non-significant both before, (CS (11.35 μm) and VE (11.86 μm)), and after cementation, (CS (20.01 μm) and VE (21.08 μm)). In terms of fracture resistance, VE recorded significantly lower fracture load values (727.8 N) (p <0.05) than the crowns fabricated from CS (1213.8 N) and VSC (1181.5 N), which showed no statistically significant differences between each other. Conclusion: 3D printed definitive crowns outperformed CAD/CAM milled crowns in terms of marginal adaptation, along with comparable fracture resistance values. Keywords: 3D printing, CAD/CAM milling, Fracture resistance , Marginal adaptation , Resin matrix ceramics

Aim: This randomized controlled clinical study focused on graft volume alterations after sinus floor augmentation with a deproteinized bovine bone mineral (DBBM, Geistlich Bio-Oss®), deproteinized porcine bone mineral (DPBM, THE GRAFT®) or a biphasic calcium phosphate (BCP, OSOPIA®). Material and Methods: 28 patients with edentulous situations in the posterior maxilla with less or equal to 5 mm of residual bone height received a two- staged external sinus grafting procedure with DBBM, DPBM or BCP. CBCT scans were performed prior surgery (CBCT1), directly after surgery (CBCT2) and after a healing period of 4-6 months prior implant placement (CBCT3). CBCT scans were used to analyze volumetric alterations of the sinus grafts by virtual 3D model matching of CBCT1- CBCT2 (situation after sinus grafting) and CBCT1 and CBCT2 (situation prior implant placement). Results: The volume of the bone graft in the maxillary sinus (volume (VOL%) directly after grafting rated as 100%) was stable after the healing period in the DBBM (VOL%: 103±4%) and the PBBM groups (VOL%: 112± 23) with no statistically significant differences concerning 3D measurements. In the BCP group, the grafted volume declined to 66± 25% (VOL%), statistically inferior to the DBBM and DPBM groups. Conclusion: Concerning bone graft stability/ 25 volume DBBM and DPBM show comparable outcomes. Due to resorption, BCP showed inferior bone graft volume after healing (statistically significant) compared to DBBM and DPBM. Keywords: 3D evaluation, Bone substitute, CBCT, Sinus grafting, volumetric stability

Aim: Even though today, many fields in dentistry allow digital processes, analogue procedures are still widely used. This cross-sectional pilot study aimed to survey insights on the digitalisation of dental practices using the example of Hesse. Materials and Methods: Between April and June 2022, 4840 active practicing dentists registered by the State Dental Association of Hesse were invited via e-mail to fill out an online questionnaire regarding their technical requirements in dental practice, dental treatment procedures, and attitude towards digitalisation in dentistry. Demographic questions were asked. Besides descriptive statistics, correlations were analyzed (P < 0.05). Result: Questionnaires of 937 dentists (279 female, 410 male, four inter/divers, 244 no answer; mean age of 51.4 ± 10.4 years) were examined representing a respond rate of 19.36%. In the area of practice administration and dental radiography, the majority of the dentists surveyed is already working digitally, which is predominantly assessed as a positive development. Already one third of the respondents state that they use an intraoral scanner for dental treatments, but the indication is mainly limited to smaller restorations. However, many dentists rate the use of social media accounts and telemedicine rather negative. Conclusion: Within the limitation of this pilot study, many processes especially in dental treatments are still analogue. However, 60% of the participants plan digitalisation of their dental practices within the next five years, which indicates a clear shift from analogue to digital dentistry. Keywords: Analog-Digital Conversion, CAD/CAM, Dental Practice Pattern, Digital Technology, Intraoral Scanner, Organisation and Administration, Real World Data on Dentistry, Surveys and Questionnaires

Objectives: Virtual Reality (VR) technologies can be used as a content-delivery system for the purposes of both entertainment and education. Remote and digital education has become ever so important in a world where global disruptive events such as pandemics and natural disasters can define access to a face-to-face learning environment. An important aspect of VR technologies for dentistry is the creation of digital 3D models. The primary of this review was to answer the focused research question, “What software techniques are used in the creation of digital 3D models for use in dental education.” Methods: This study systematically evaluates current software and techniques used for creating digital 3D models in dental education using the Preferred Reporting Items for Systematic Reviews (PRIMSA). Results: The search strategies did not find any studies specific to the creation of dental-related 3D models. Therefore, this study for the first time provided an overview of common techniques of 3D model fabrication is discussed. Further some examples of methods of creating 3D models relevant to dentistry such armamentarium and anatomical oral structures have been discussed in considerable detail. Conclusion: The creation of 3D modelling is a rapidly evolving field with software updates and new programs being continually released. This work highlights fundamental lack of published work in the creation of 3D dental models for educational applications. Keywords: 3D modelling, dental education; , dentistry, digital modelling, Virtual Reality

Aim: The purpose of this systematic review and meta-analysis is to evaluate the marginal adaptation of single unit full coverage lithium disilicate fixed dental restorations fabricated with the conventional heat pressed technique and the digital CAD/CAM workflow. Materials and Methods: This study is according to the Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) statement. study research was conducted in MEDLINE via PubMed and Cochrane Library databases together with a hand search of studies published until June 2022. The search terms were combining suitable Medical Subject Headings (MeSH terms) together with free text words in single or multiple conjunctions. A modified methodological index was used to assess the risk of bias of the included studies. A random effect model was applied to pool the effect estimates, and further assessment of the heterogeneity across studies using the Q test and the I2 metric was conducted. All statistical analyses were performed using Rstudio software, version 4.1.2, using the “meta” package. Results: The electronic search and hand search identified 51 articles. Eighteen met the inclusion criteria and were included in the systematic review, 17 of which were in vitro and only one was an in vivo study. However, 17 of the initial 18 could be included in the meta-analysis, due to lack of statistical data in one of the in vitro studies. Statistical analyses were conducted by using the Rstudio software program. Meta-analysis was performed with the random effects model (α=.05). No statistical difference was found between the two fabrication methods (p-value=0.49). Conclusions: Although the mean marginal adaptation of lithium disilicate single crowns was found to be better with the heat-pressed technique, there was no statistical significance with the CAD/CAM fabricated restorations and both resulted in a clinically acceptable result. Nonetheless, more clinical studies are needed for safer conclusions. Keywords: all-ceramic restoration, CAD/CAM, dental ceramics, glass-ceramics, lithium disilicate crown, marginal fit, single crown