Intraoral scanner-based monitoring of tooth wear in young adults: 36-month results.

OBJECTIVES: The study continues our longitudinal observation of wear aiming to further monitoring of progression and lesion morphology and to identify relationships with assumed aetiological factors. MATERIALS AND METHODS: Molars (FDI #36 or #46) of 74 participants (23.8 ± 2.2 years) were scanned (Trios 3, 3Shape) at the third follow-up (T3; observation period 1,111 ± 10 days). Data sets from T3, T2 (24-month follow-up) and T1 (12-month follow-up) were superimposed with baseline in a 3D analysis software (GOM Inspect). Wear was quantified as maximum vertical tissue loss (µm; median, 95% CI) in various occlusal areas (4/5 cusps and 2 ridges). Morphologies were classified into cupping (C), facet (F), and combined cupping-facet (CF). Aetiological factors were assessed with questionnaires. RESULTS: Wear increased at T3 significantly at low rates in all areas of the occlusal surface (median between 7.0 (4.0;10.5) and 9.5 (6.0;15.0) µm). There was a clear trend for higher loss values in males, but no association with other factors such as nutrition. C and CF showed significantly higher loss values than F. Areas without initial wear developed F first, which either persisted or developed into C and CF. CONCLUSIONS: Wear continued at low rates with C/CF morphology and sex as significant factors. Cupped lesions seem to develop from facets and thus may not be a valid diagnostic criterion for erosive tooth wear. CLINICAL RELEVANCE: Wear is a cumulative process that apparently follows complex mechanisms that cannot be conceptualized in simplified terms; C and CF may be indicators for higher progression rates.

A comparative retrospective study on the prevalence and therapeutic treatment of dental agenesis between healthy children and children with systemic disease or congenital malformation.

BACKGROUND: Dental agenesis (DA) in the permanent dentition is one of the most common dental anomalies, with a prevalence up to 2-10%. Therefore, the aim of this retrospective study was to investigate the prevalence and therapeutic treatment of DA in healthy children (HC) compared to children with systemic disease or congenital malformation (SD/CM). METHODS: Out of 3407 patients treated at the Department of Paediatric Dentistry of the Justus Liebig University Giessen (Germany) between January 2015 and December 2020, a total of 1067 patients (594 female, 473 male) aged between 4.5 and 18 years were included in this study due to DA. Besides the patients' general medical history and therapeutic treatments, panoramic radiographs were analysed. RESULTS: In contrast to the HC group with 9.7% DA, the SD/CM group showed a significantly higher prevalence of DA (19.8%; p < 0.05). The latter group was further classified into children with ectodermal dysplasia (4.4%), down syndrome (8.2%), cleft lip and palate (4.4%), intellectual disability/developmental delay (16.4%), and other genetic/organic diseases without intellectual disability (45.9%). Regarding therapeutic treatments, the HC group (59.5%) was significantly more often treated with an orthodontic gap opening compared to the SD/CM group (42.6%; p < 0.05), followed by orthodontic gap closing 36.5% in the HC group and 22.9% in the SD/CM group (p < 0.05), whereas no treatment was predominantly performed in the SD/CM group (37.7%) compared to the HC group (4%; p < 0.05). Furthermore, 50% in the SD/CM group required general anaesthesia for therapeutic treatment (vs. 8.1% in the HC group; p < 0.05). CONCLUSIONS: Children with SD/CM suffered more often from DA compared to HC that underlines multi- and interdisciplinary treatment of utmost importance. Furthermore, due to intellectual disability, common treatment methods can be complicated by insufficient compliance. This fact underlines the importance of an early attempt to establish the necessary cooperation enabling children with SD/CM to receive therapy.

Intraoral scanner-based monitoring of tooth wear in young adults: 24-month results.

OBJECTIVES: Tooth wear causes irreversible cumulated surface loss and already occurs at a young age. Therefore, the objective of this clinical prospective observational study was to monitor the occlusal surface of a mandibular first molar in young adults for a period of 24 months. Furthermore, potential aetiological factors obtained by a questionnaire were considered. MATERIALS AND METHODS: The study teeth (FDI #36 or #46) of 81 participants (mean age 22.8 ± 2.2 years) were scanned with the intraoral scanner (IOS, Trios 3, 3Shape) at the second follow-up (T2) after an observation period of 24 months. Standard-tessellation-language datasets were superimposed with baseline (T0) and T2 scans in 3D analysis software (GOM Inspect). The maximum vertical substance loss was measured between T0 and T2 at 6/7 areas (4/5 cusps and 2 ridges) of each study tooth and data compared to the already published data of the first follow-up (T1) after 12-month observation period. The morphology of tooth wear was classified into three groups: cupping (C), facet (F) and combined cupping-facet (CF). The analysis of aetiological factors, such as acid impacts, was based on a questionnaire filled out by participants at time points T0, T1 and T2. Non-parametric tests were used for statistical analysis (p < 0.05). RESULTS: The buccal load-bearing cusps (mesiobuccal: median 15 µm, 95%CI 11/18 µm; mesiolingual 8 µm, 0/11 µm) were most affected by tooth wear. Loss values increased significantly at T2 compared to T1 for all areas, although significantly less than in the first 12 months (T0-T1). Areas that already exhibited F at T0 mostly displayed them also at T2 and only rarely developed further into C or CF. The only association between aetiological factors and loss values could be detected for sex as males had significantly higher loss values than females. CONCLUSIONS: Progression of tooth wear could be clearly shown with high interindividual variations in loss values among participants. This indicates the need for individual monitoring with IOS. CLINICAL RELEVANCE: IOSs show the potential for patient-specific monitoring to detect the progression of tooth wear. Thus, data of 24 months fills the gap of tooth wear data for young adults in literature. Further studies over a longer observation period are highly recommended to gain more information about the dynamic of tooth wear and aetiological factors.

Update of students' and lecturers' perspectives on online learning in dental education after a five-semester experience due to the SARS-CoV-2 (COVID-19) pandemic: insights for future curriculum reform.

BACKGROUND: The coronavirus disease (COVID-19) pandemic has accelerated digital transformation in dental education, resulting in a shift from face-to-face teaching to online learning. While online learning could be a common strategy in various fields, the challenge for dental education is that it depends on the requirements of clinical experience to achieve competence in performing the dental treatment. This cross-sectional study aimed to analyse students' and lecturers' perceptions towards online learning after five semesters of experience using a questionnaire survey. METHODS: Since the spring term of 2020, the theoretical part of the curriculum has been conducted in the form of online learning using a combination of synchronous and asynchronous formats. In the following semesters, more theoretical content was shifted back from online learning to face-to-face courses. Preclinical and clinical students enrolled in the dental curriculum during the spring term 2022 semester and all lecturers with at least one year of teaching experience in face-to-face and online learning formats were asked to fill out an online questionnaire regarding the aspects of handling, didactic benefit, motivation, and overall assessment. RESULTS: Students and lecturers rated the implementation of online learning as mostly positive, but pointed out that established 'face-to-face' learning could not be replaced. Moreover, the students reported personal benefits in terms of daily planning. Lecturers also benefitted as their experience increased in online teaching. For future curriculum, students demanded 49.5% (25.1) ((mean (standard deviation) of theoretical part in terms of online learning), while lecturers demanded only 34.1% (24.1). CONCLUSIONS: Despite having no prior need for online learning, students and lecturers showed a positive perspective on online learning which should be considered in the implementation and planning of future dental education. However, in terms of practical training, it cannot replace face-to-face education in dentistry.

The transfer accuracy of digital and conventional full-arch impressions influenced by fixed orthodontic appliances: a reference aid-based in vitro study.

OBJECTIVES: The aim of this in vitro study was to investigate the influence of fixed orthodontic appliances (FOAs) on the transfer accuracy of full-arch impressions by five intraoral scanners (IOSs): CS3600, Primescan, Trios 4, Medit i500, Emerald S, and one conventional alginate impression (CAI). MATERIALS AND METHODS: To compare the data with the actual model situation, an established reference aid-based method was applied. A test model with human teeth was used and modified for each testing group, resulting in five different settings: natural teeth (group A), metal brackets without/with wire (groups B/C), ceramic brackets without/with wire (groups D/E). A total of 300 (n = 12 × 5 × 5) scan datasets of IOSs were analyzed using a 3D software (GOM Inspect) and 60 (n = 12 × 5) plaster casts of CAI were measured with a coordinate measurement machine. The deviations between the reference aid and the impressions were determined. RESULTS: For all groups with brackets (B to E), IOSs showed a higher transfer accuracy compared to CAI, even for long-span distances. However, some significant differences between the IOSs were observed (p < 0.05). CONCLUSIONS: Within the limitations of this in vitro study, IOSs can be recommended for impressions with and without FOAs, even if CAI showed the smallest average deviations in settings without FOAs. CLINICAL RELEVANCE: IOSs are widely used in orthodontics and the current study demonstrated that their use enables fast impression taking even in settings with fixed orthodontic appliances. In addition, for these settings, the transfer accuracy is higher than with conventional alginate impressions. Nevertheless, a re-investigation in a clinical setting should be performed to verify the current in vitro findings.

Insights on the digitalisation of dental practices: A cross-sectional pilot study in Hesse.

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.

[Geriatric assessment in dentistry : A review of chewing function tests]. / Geriatrisches Assessment in der Zahnmedizin : Eine Übersicht zu Kaufunktionstests.

Due to increasing life expectancy and the associated demographic changes, more and more people are dependent on care. To identify a possible need for dental treatment, chewing function tests as assessment instruments have proven their effectiveness. In this article, the reader is given an overview of existing chewing function tests and their implementation. It is important that a patient with pain should be presented to a dentist immediately, regardless of whether a chewing function test is performed. Furthermore, chewing function tests are not a substitute for routine dental examinations, but they could provide information to (dental) laypersons as to whether an appointment should be arranged in a dental practice or whether a dental consultation is necessary.

Accuracy of digital implant impressions in clinical studies: A systematic review.

OBJECTIVES: The use of intraoral scanners (IOSs) for digital implant impressions in daily clinical practice is increasing. However, no structured literature review on the accuracy of digital implant impressions in clinical studies has been described to date. Therefore, this systematic review aimed to answer the PICO question: Which accuracy is described for digital implant impressions in clinical studies? MATERIAL AND METHODS: An electronic database search was conducted in December 2021 using MeSH terms and free-text search. English-language studies addressing the accuracy of digital implant impressions in clinical studies involving at least 10 patients were included. All clinical indications were considered. RESULTS: Eight publications between 2014 and 2021 matched the review criteria. However, the study designs showed considerable differences. The number of implants within the studies ranged from 1 to 6, and the number of patients ranged from 10 to 39. The oldest study (2014) revealed the highest deviation for linear distances at 1000 ± 650 µm, whereas the other studies reported data in the range of 360 ± 46 µm to 40 ± 20 µm. In one study, no numerical data were reported and all studies compared digital and conventional implant impressions. CONCLUSIONS: The number of clinical studies on the accuracy of digital implant impressions is low. Thus, the impact of different factors, such as the scanpath or scanbody, could not be identified. However, the accuracy of recent IOSs for digital implant impressions in patients was shown to be clinically acceptable. Nevertheless, the transfer error still needs to be considered when fabricating implant-supported restorations.

Intraoral scanner-based monitoring of tooth wear in young adults: 12-month results.

OBJECTIVES: To investigate tooth wear in young adults, intraoral scanning was used for digital monitoring of the mandibular first molar over 12 months. A possible influence of aetiological factors obtained by a questionnaire on tooth wear was investigated. MATERIALS AND METHODS: A total of 109 participants (mean age at the start of the study: 21.0 ± 2.2 years) were included in this clinical study. At baseline (T0), an intraoral scan (Trios 3, 3Shape) of the study tooth (FDI # 36 or #46) was conducted. After a mean observation period of 373 ± 19 days, a second intraoral scan (T1, n = 94) of the same tooth as at T0 was performed and standard tessellation language datasets were superimposed with 3D analysis software (GOM Inspect). The occlusal surface of the study tooth was divided into 7 areas (5 cusps, 2 ridges) and maximum vertical substance loss was measured between T0 and T1 (n = 91). Three types of tooth wear were defined: cupping (C), facet (F) and combined cupping-facet (CF). Furthermore, a questionnaire on aetiological factors, such as dietary behaviour, was filled out at T0. Data were analysed with non-parametric tests (p < 0.05). RESULTS: Only one study tooth exhibited no tooth wear at T0, whereas 3 teeth showed C, 47 teeth F and 40 teeth CF. A progression of vertical substance loss for all three types was shown. Most affected were the mesiobuccal cusps (43, 38/47 µm; median, 95%CI) followed by distobuccal (36, 33/39 µm), mesiolingual (35, 26/40 µm), distolingual (34, 27/36 µm) and distal (31, 25/34 µm). On mesial and distal ridges, only F was detected with the lowest vertical substance loss of all areas (mesial ridge: 0, 0/0 µm; distal ridge: 0, 0/0 µm). An association between aetiological factors and loss values could not be shown. CONCLUSIONS: All study teeth showed clear signs of wear, and after only 1 year, further substance loss was detectable. This result is of significance for young adults. CLINICAL RELEVANCE: Since data of young adults regarding tooth wear are scarce, the results give a first idea of the amount of vertical loss per year and its relation to aetiological factors such as dietary behaviour. Therefore, further studies over a longer observation period are highly recommended.

New Caries Diagnostic Tools in Intraoral Scanners: A Comparative In Vitro Study to Established Methods in Permanent and Primary Teeth.

The aim of this in vitro study was to systematically investigate new caries diagnostic tools, including three intraoral scanners, and compare them to established diagnostic methods. For a standardized analysis of occlusal and proximal caries lesions, human permanent and primary teeth (n = 64) were embedded in models and investigated in a phantom head using six different caries diagnostic methods: visual examination, bitewing radiography, Diagnocam (KaVo, Biberach, Germany), Trios 4 (3Shape, Copenhagen, Denmark), iTero Element 5D (Align Technology, San José, CA, USA), and Planmeca Emerald S (Planmeca, Helsinki, Finland). The diagnostic methods were investigated and compared to reference µ-CT for permanent and primary teeth separately. For occlusal caries diagnostics in permanent teeth, the best agreement to the reference (reliability) was obtained for Planmeca Emerald S (ĸ = 0.700), whereas in primary teeth, for visual examination (ĸ = 0.927), followed by Trios 4 (ĸ = 0.579). Regarding proximal caries diagnostics, bitewing radiography, as the gold standard, exhibited the highest agreement for permanent (ĸ = 0.643) and primary teeth (ĸ = 0.871). Concerning the analysis of the diagnostic quality (sensitivity and specificity) using receiver operating characteristic (ROC) curve analysis, comparable findings were obtained for area under curve (AUC) values as for reliability. No diagnostic method could be identified that is generally suitable for occlusal and proximal lesions in both dentitions. Overall, caries diagnostics with intraoral scanners seem to be interesting tools that should be further investigated in clinical studies.

A comparative clinical study on the transfer accuracy of conventional and digital implant impressions using a new reference key-based method.

OBJECTIVES: The objective of this study was to systematically compare the transfer accuracy of conventional and digital implant impressions in patients using a new reference key-based method. MATERIAL AND METHODS: Thirty-nine cases were included in the study (upper jaw 22 edentulous, 8 partially edentulous, average distance between implants 30.15 ± 11.18 mm; lower jaw 6 cases edentulous, 3 cases partially edentulous, average distance between implants 33.19 ± 14.85 mm). Individual reference keys were manufactured and reversibly fixed on implants. A conventional (CVI) and a digital (DI) implant impression was made. The implant positions (center points) of conventional and digital models were measured (coordinate-measuring machine/three-dimensional analysis software) and superimposed with the positions of the reference keys to compare the deviations of the conventional and digital models. For statistical analysis, ANOVA with MIXED procedure was applied (p < .05). RESULTS: Mean deviation ranged from 0.040±0.029 mm (DI/upper jaw) to 0.079 ± 0.050 mm (DI/lower jaw). There were significant differences between the CVI and DI impressions in the lower jaw (p < .05). No significant differences in transfer accuracy were found between partially and completely edentulous patients for the impression methods. CONCLUSIONS: Within the limits of the present study, it can be concluded that full-arch digital implant impressions of the upper jaw in partially or completely edentulous patients showed comparable results to conventional implant impressions. However, with regard to the implant position transfer accuracy, there are still limitations for digital impression in the lower jaw.

Do different methods of digital data analysis lead to different results?

AIM: Dental research involves variations between actual and reference datasets of master models to determine the metric accuracy through transfer accuracy tests. Various methods of measurement are used to analyze the results, which are often subjected to direct comparisons. Hence, the aim of the present study was to analyze the influence and effect on results of different methods of digital data analysis, being coordinate-based analysis (CBA) and best-fit superimposition analysis. MATERIALS AND METHODS: A model with four implants and a reference cuboid was digitized through computed tomography (CT), which served as the master model. Ten implant impressions were made using a Trios (3Shape) intraoral scanner, and three different scan bodies (nt-trading, Kulzer, and Medentika) were used. The deviations between the master model and the digital impressions were analyzed using CBA and best-fit superimposition analysis. Statistical analysis was performed using SPSS 25. RESULTS: The deviations in the CBA and best-fit superimposition analysis ranged from 0.088 ± 0.012 mm (mean ± SE; Medentika, 14) to 0.199 ± 0.021 mm (Kulzer, 26), and from 0.042 ± 0.010 mm (Medentika, 16) to 0.074 ± 0.006 mm (Kulzer, 16), respectively. Significant differences were observed between the implant positions in the CBA and the digital measurements at each implant position, whereas the best-fit analysis showed no significant difference between the scan bodies and implant positions. CONCLUSION: CBA displays an advantage over best-fit superimposition analysis in the detection of possible influencing factors for primarily scientific purposes. However, a global analysis and visualization of angles and torsions is difficult, for which a best-fit evaluation is needed. However, a best-fit analysis better represents the clinical try-in. It is associated with the risk that possible disturbing factors and resulting errors might be leveled out and their identification camouflaged.

Students' and lecturers' perspective on the implementation of online learning in dental education due to SARS-CoV-2 (COVID-19): a cross-sectional study.

BACKGROUND: On account of physical distancing measures, universities worldwide are strongly affected by SARS-CoV-2 (COVID-19). Thus, the dental school of Justus-Liebig-University Giessen (Germany) transferred the established "face-to-face" learning to online learning in the spring term 2020. The aim of this study was to assess the students' and lecturers' perspectives on the implementation of online learning due to COVID-19, using a questionnaire survey. METHODS: After the online period, all students and lecturers were asked to fill out an online questionnaire containing evaluative statements regarding handling, didactic benefit, motivation, and overall assessment. Furthermore, the questionnaire for lecturers contained additional aspects regarding knowledge gain in terms of providing online learning. Besides that, students and lecturers were asked for the amount of online learning in the future curriculum (independent of COVID-19). Data were subjected to regression analysis and T-test (p < .05). RESULTS: 36.8% of students preferred "face-to-face" learning instead of sole online learning. An increase of know how concerning online teaching was observable for lecturers. Both, students and lecturers, want to keep up with online courses in the future curriculum. However, in terms of the optimal amount of online learning a significant difference between students' and lecturers' perspective was observed. While students suggested 53.2% (24.9) (mean (standard deviation)) lecturers only stated 38.6% (21.5). CONCLUSIONS: Within the limitation of this study, students' and lecturers' showed a predominantly positive perspective on the implementation of online learning, providing the chance to use online learning even beyond COVID-19 in the future curriculum.

Chairside measurement of the marginal and internal fit of crowns: a new intraoral scan-based approach.

OBJECTIVES: To investigate the marginal and internal fit of crowns, a new intraoral scanner-based digital approach for chairside measurement (D-IOS) was systematically analysed and compared with the conventional silicone replica technique (CV-SR) and digital 3D analysis software (D-GOM). MATERIALS AND METHODS: Two models, representing different clinical situations, were constructed, and the first molar was prepared for a full-coverage crown. On the basis of an intraoral scan (Trios 3), copings of three different materials (non-precious alloy, zirconium dioxide, and resin composite) with two different cement spaces (80 µm, 50 µm) were manufactured. The fit of the copings was investigated by all three methods (CV-SR, D-IOS, D-GOM). Therefore, the cement space was visualized with low-viscosity silicone and digitalized with a second intraoral scan. Evaluation of fit by the D-IOS-method was measured in the intraoral scanner software, whereas for analysis by D-GOM, both intraoral scan datasets were transferred to 3D analysis software (GOM Inspect). The CV-SR-method was used as a control group. For all copings, the measurements were repeated five times. The data were analysed with ANOVA. RESULTS: No significant differences between the three evaluation methods and the coping materials were shown. However, in the occlusal area, the internal gap was significantly higher compared to the internal gap in the marginal and axial areas regardless of the cement space setting (p < .05). The target parameter of the cement spaces did not match the actual measured internal gaps. CONCLUSIONS: All three evaluation methods and coping materials can be used for the measurement of fit within different clinical situations. CLINICAL RELEVANCE: The digital chairside measurement implemented in the intraoral scanner software enables an easy, applicable evaluation of fit of crowns without additional laboratory devices or special software applications.

Undergraduate dental students' perspective on the implementation of digital dentistry in the preclinical curriculum: a questionnaire survey.

BACKGROUND: Digitalisation is an expanding field in dentistry and implementation of digital teaching methods in dental education is an essential part of modern education. Therefore, two digital training modules were implemented in the preclinical curriculum at the Justus Liebig University Giessen. The aim of this study was to assess the students' perspective on the implementation with a questionnaire survey. METHODS: Since the fall term 2017/18, students of the course of dental prosthodontics I attended the training module I, where they learned to use computer-aided learning (CAL) approaches for the digital analysis of tooth preparations. In training module II, students of the course of dental prosthodontics II learned how to manufacture a computer-aided design/computer-aided manufacturing restoration. After the completion of the training modules, all students starting with the fall term 2017/18 to the spring term 2019 were asked to fill in a questionnaire regarding the aspects of handling, didactic benefit, motivation, and overall assessment. RESULTS: Students rated the implementation of digital aspects in teaching as positive in terms of handling, didactic benefit, and motivation, but gave preference to the assessment of the tooth preparations by dental instructors. In addition, students assessed the feedback from the faculty regarding tips and tricks better than the digital feedback. More than 90% of the students indicated that they could imagine using an intraoral scanner for treatment of patients in the dental office in future. CONCLUSIONS: The results of the present study revealed a positive perspective of students on the implementation of digital dentistry in the preclinical curriculum. However, difficulties with CAL systems were reported and most students preferred evaluation of preparation by dental instructors. Thus, CAL approaches offer an additional teaching method besides the traditional teaching of manual skills.

Microleakage of composite crowns luted on CAD/CAM-milled human molars: a new method for standardized in vitro tests.

OBJECTIVES: To investigate debonding of full crowns made of CAD/CAM composites, CAD/CAM technology was applied to manufacture standardized test abutments to increase the reproducibility of human teeth used in in vitro studies. MATERIALS AND METHODS: A virtual test abutment and the corresponding virtual crown were designed and two STL data sets were generated. Sixty-four human third molars and CAD/CAM blocks were milled using a CNC machine. Crowns of four different composite blocks (Lava Ultimate (LU), Brilliant Crios (BC), Cerasmart (CS), Experimental (EX)) were adhesively bonded with their corresponding luting system (LU: Scotchbond Universal/RelyX Ultimate; BC: One Coat 7 Universal/DuoCem; CS: G-PremioBond/G-Cem LinkForce; EX: Experimental-Bond/Experimental-Luting-Cement). Half of the specimens were chemical-cured (CC) and the others were light-cured (LC). Afterwards, specimens were artificially aged in a chewing simulator (WL-tec, 1 million cycles, 50-500 N, 2 Hz, 37 °C). Finally, a dye penetration test was used to detect debonding. For inspection, the specimens were sliced, and penetration depth was measured with a digital microscope. Data were analyzed with the Mann-Whitney U test. RESULTS: No cases of total debonding were observed after cyclic loading. However, the LC specimens showed a significantly lower amount of leakage than the CC ones (p < 0.05). Furthermore, the CC specimens exhibited broad scattering. Only the LC-EX blocks showed no debonding. The CC-CS blocks showed the highest leakage and scattering of all tested specimens. CONCLUSIONS: Natural human teeth can be manufactured by CAD/CAM technology in highly standardized test abutments for in vitro testing. For CAD/CAM composites, light curing should be performed. CLINICAL RELEVANCE: The success of a restoration depends on the long-term sealing ability of the luting materials, which avoids debonding along with microleakage. For CAD/CAM composites, separate light curing of the adhesive and luting composite is highly recommended.

In vitro comparison of analog versus digital impressions of the periodontally compromised dentition focused on interdental areas.

AIM: For orthodontic aligner treatment, excellent full-arch impressions with correctly displayed interdental areas (IAs) are required. To analyze the ability of impression taking of the IAs in periodontally compromised dentitions, two intraoral scanning systems and one conventional impression technique were investigated in vitro under standardized testing conditions. MATERIALS AND METHODS: A total of 60 impressions of the maxilla and mandible were taken from a periodontally compromised test model (A-PB) with three different techniques (n = 20): One conventional impression (EXA'lence) (CVI) and two digital impressions with the intraoral scanners Trios III (3Shape) (TIO) and True Definition (3M ESPE) (TRU). Standard tessellation language (STL) datasets were generated for TIO and TRU, whereas type IV dental stone casts were manufactured for CVI. The casts were then digitized with a laboratory scanner (ATOS). The percentage of displayed IAs in relation to the complete IA was calculated for each IA using evaluation software (GOM Inspect). Finally, the data were subjected to the median test. RESULT: TRU showed a significantly higher percentage of displayed IAs compared with the other two methods (P < 0.05). Only a few IAs were shown in CVI. TIO showed significantly better results compared with CVI, although the results were not as good as those of TRU. CONCLUSION: Within the limitations of this in vitro study, intraoral scanners - and especially the one based on active wavefront sampling (AWS) technology (as for TRU) - can be recommended for the reproduction of wide IAs (undercuts) in periodontally compromised patients.

Update on the Accuracy of Digital Implant Impressions in 2023: A Coordinate-Based Analysis.

PURPOSE: To update data on the transfer accuracy of digital implant impressions by using a coordinate-based analysis, latest intraoral scanners (IOSs) were investigated in an established clinical close model set-up. MATERIALS AND METHODS: An implant master model (IMM) of the maxilla with four implants in the posterior area (#14/#24 and #16/#26) and a reference cube was scanned with four different IOS (i700 (Medit), Primescan (Dentsply Sirona), Trios 4 and Trios 5 (3Shape) ten times each. Datasets were compared with a reference dataset of IMM that was generated with x-ray computed tomography in advance. 3D deviations for the implant-abutment-interface points (IAIPs) were calculated. Statistical analysis was performed by multifactorial ANOVA (p < .05). RESULTS: Overall deviations for trueness (mean) ± precision (SD) of the IAIPs ranged from 88±47 µm for the Primescan, followed by 112±57 µm for the i700, 121±42 µm for the Trios 4 and 124±43 µm for the Trios 5 with decreasing accuracy along the scan path. For trueness, one significant difference between the Primescan and the T4 was detected for one implant position. For precision, no significant differences were noticed. CONCLUSIONS: Although the latest IOS showed a significant improvement in transfer accuracy, the accumulating deviation along the scan path is not yet resolved. Considering the Trios system, the innovation seems to be limited as no improvement could be detected between Trios 4 and 5.

Digital plaque monitoring: An evaluation of different intraoral scanners.

OBJECTIVES: Intraoral scanners (IOS) display disclosed plaque, and the scientific literature has reported that plaque levels can be monitored on intraoral scans using one IOS system (Dexis 3800; control IOS). This study aimed to investigate whether this is also possible with other IOS systems (i700, Primescan, Trios 5; test IOS). MATERIALS AND METHODS: Ten participants (29.6 ± 5.5 years) were enrolled. After plaque accumulation and subsequent toothbrushing, intraoral scans were performed with the control IOS and the three test IOS. All scans were aligned and the vestibular/oral surfaces of the Ramfjord teeth (16, 21, 24, 36, 41, 44) were analysed with automated planimetry using a predefined threshold value. The proportion of pixels assigned to plaque-covered areas was expressed as a percentage of the total number of pixels (P%). We then assessed whether the planimetrically determined plaque-covered areas corresponded to those identified visually. This revealed that a threshold correction (P%corr) was required for approximately 20 % (i700 and Trios 5) to over 65 % (Primescan) of the images. RESULTS: Bland-Altman analysis showed no significant systematic bias and limits of agreement ranging from approximately -20 to +20 P% units, with a tendency towards lower values at higher plaque coverage. Manual correction improved the agreement and halved the limits of agreement. All test IOS could detect a reduction in plaque after brushing, as well as the typical site-dependant plaque distribution patterns. CONCLUSIONS: All test IOS appeared to be suitable for plaque monitoring. Planimetric methods must be adapted to the colour representation of the IOS. CLINICAL SIGNIFICANCE: Plaque monitoring using IOS opens a new field of application in preventive dentistry.

Occlusal Caries Detection with Intraoral Scanners in Pediatric Dentistry: A Comparative Clinical Study.

Background: The aim of this clinical study was to compare the occlusal caries detection (OCD) performance of the intraoral scanners (IOSs) Trios 4 (TIO, 3Shape) and Emerald S (EME, Planmeca) and the Diagnocam (DIA, KaVo) with the established visual (WHO) examination (VIS, reference method). Methods: Between 08/2022 and 02/2023, 60 children (mean age 9.6 ± 2.5 years) were examined as part of their regular dental checkups. OCD was performed at the tooth level, separately for primary and permanent unrestored teeth. Furthermore, two thresholds were analyzed: sound versus overall caries (pooled data of enamel and dentin caries, TH1) and pooled data of sound and enamel caries versus dentin caries (TH2). Results: The best agreement with the reference method (reliability) in both dentitions was obtained for DIA (ĸ = 0.829/ĸ = 0.846; primary/permanent teeth), followed by EME (ĸ = 0.827/ĸ = 0.837) and TIO (ĸ = 0.714/ĸ = 0.680). Similar results were shown for the diagnostic quality (sensitivity, specificity and area under the curve of the receiver operating characteristic curve), with higher values for TH1 than for TH2. Both IOSs and the DIA showed worse results than the reference method VIS. Conclusions: Currently, IOS should be used as an additional caries detection tool, especially for visualization, and cannot be recommended as a basic tool for diagnosis or invasive/noninvasive therapy decisions in OCD.