International Journal of Computerized Dentistry, 04/2018

Functional diagnostic examinations such as clinical functional analysis and manual structural analysis ('orthopedic tests') allow the dentist to establish a structured diagnosis. Previously, the process of correlating findings with the appropriate diagnoses was guided by human thought processes alone. The experimental diagnostic randomized controlled trial (RCT) in this study investigated whether computer-aided diagnosis (CADx) of temporomandibular disorders (TMD) offers quality advantages over traditional diagnosis (TRAD). Subjects and methods: Thirty-nine 5th-year dental students (examiners) at a university in Hamburg, Germany, received joint training in the diagnosis of TMD by clinical functional analysis and manual structural analysis ('orthopedic tests'). This study is based on anonymized data from 10 patients who were consecutively recruited at a specialized TMJ treatment center. The examiners were randomly allocated to two groups. Each examiner established a structured diagnosis through a traditional diagnostic method and by computer-aided diagnosis (CMDfact 4 functional diagnostics software) of five cases, each using the AB/BA crossover design. The diagnoses established by each individual examiner were then compared with the corresponding reference diagnoses (gold standard) and with those of the other examiners. Results: Cohen's kappa coefficient analysis showed that median agreement with the reference diagnoses was significantly higher (P 0.001) with computer assistance (median 0.692) than without it (0.553). Fleiss' kappa showed that the median interexaminer consistency of diagnoses was significantly higher (P 0.001) with computer assistance (0.497) than with traditional diagnostic methods alone (0.271). Likewise, the number of false-positive and false-negative diagnoses was significantly lower with computer assistance (P 0.001). Conclusions: This study determined that dentists who are less experienced and not specialized in dental functional diagnostics achieve a significantly better and more consistent diagnostic quality with computer assistance by means of the system used in this study. Therefore, it seems advisable to extend computer-aided diagnostics to further functional examination techniques (condylar position analysis and jaw motion analysis). Keywords: computer-aided diagnostics, temporomandibular disorders (TMD), clinical functional analysis, manual structural analysis, orthopedic tests, randomized controlled trial, diagnostic classification, CMDfact

Terminal hinge axis (THA) determination is recommended in some clinical situations and for some diagnostic purposes. Different methods are described and are available for this task. In particular, circle fitting or iterative trace recording methods, in the conventional process known as the pantographic or Lauritzen method, have mostly been applied in clinical settings and have even been used as exact reference measures in many studies. The aim of this study was to investigate whether the conditions for THA determination by these methods principally allow for the differentiation between a pure rotational movement and a combined translational and rotational movement. A further question relates to how large the uncertainties are if an additional translational movement is present during the first phase of mouth opening or closing. These questions were investigated by an exact simulation. The methods under consideration are seen to be able to detect a pure rotational movement, if one or both of the following conditions are met: a) the traces recorded around the rotational center perform a circlelike motion, and b) a point or pin on the rotational center remains at rest during movement. It can be proven that in the relevant clinical situation these conditions also hold in the case of a combination of translational and rotational movement. Furthermore, small translations of 1.1 mm lead to a deviation of the THA of around ± 6.7 mm, and a translation of 2.2 mm to an uncertainty of even ± 13.5 mm. The significance of these results suggests that the commonly used methods for THA determination should be reevaluated, and the literature on this topic should be carefully scrutinized. Keywords: Terminal hinge axis, temporomandibular joint, pantographic method, articulator, computer simulation

Recent reports in the literature demonstrate the influence that digital dentistry is having on the preclinical training of dental students. However, none of these articles have discussed the use of PrepCheck (Sirona Dental Systems) in the evaluation of preparation taper in a preclinical environment. The present study compared the subjective grading of student tooth preparations by experienced, well-calibrated faculty with objective digital grading of the same preparations by means of the PrepCheck software. Sixty-nine sophomore dental student preparations were first subjectively graded by their dental instructors, and then the preparations were evaluated by the PrepCheck software. Neither the students nor the instructors were aware that the second PrepCheck evaluation was going to occur. The statistically significant results of this study conclude that the subjective instructor grades were inflated compared with the digital PrepCheck grades. The inflated grading by the instructors may give students a sense that their progress is better than it actually is. The objective, exact nature of the PrepCheck evaluation gives students immediate feedback regarding their preclinical preparations. Although taper was the only parameter examined in this study, PrepCheck allows the operator to examine many other features of a student's preparation. Also made evident in this study is the fact that the present standard for preparation taper is unattainable in a preclinical environment and needs to be readjusted to a wider, attainable range. Keywords: education technology, digital grading, PrepCheck, preparation taper

The aim of the present study was to develop an analytical computer-supported assessment concept for the objective evaluation of students' practical skills, and to investigate the assessor-dependent differences by setting tolerance limits applied during the 'glance and grade' evaluation. A sample of 54 conventionally supervised dental undergraduates were given training in the preparation of a macroretentive Class II cavity. The course participants then took a mandatory practical examination. Three (plus one) course instructors performed the visual evaluations of the examination tasks according to predefined assessment criteria, followed by optical impressions (quadrant scan using Omnicam; Cerec; Dentsply Sirona, Wals, Austria) and subsequent assessment of the prepared cavities (tooth 46) using the prepCheck application (Dentsply Sirona). In this course, the maximum permissible deviation was set at ± 10% from the predefined assessment criteria. If no tolerance was applied, the statistical analysis revealed a significant difference between the actually achieved cavity dimensions and the predefined values of a master preparation (P = 0.0001; Student's t-test), thus leading to an overall failure rate of 100%. The application of the initially targeted 10% tolerance led to an insignificant reduction (96.3%), while the stepwise elevation of the permissible deviation up to 35% finally matched with the result of the visual assessment (total failure rate of approximately 20%). Unlike the pronounced subjectivity of the tutors during the assessment of students' practical skills, the utilization of the prepCheck application enables precise evaluations. Further studies are clearly warranted to investigate the possible educational outcome of an advanced interactive computer-supported training with implemented tolerance corridors. Keywords: computer-aided assessment, phantom lab, practical skills, preclinical dental education, prepCheck

Objective: To evaluate the accuracy of the new endodontic planning software (3D Endo Dentsply Sirona) based on cone beam computed tomography (CBCT) to predetermine root canal lengths compared with measurements performed with an electronic apex locator (Raypex 6; VDW) ex vivo. Materials and methods: CBCT scans of forty extracted human maxillary (n = 20) and mandibular (n = 20) molars were taken, and root canal lengths were predetermined with the 3D Endo software using the apical foramen (AF) and the adjoining cusp as references. Root canal lengths were determined with the Raypex 6 using the same references. To evaluate the accuracy, absolute differences between both methods and the actual root canal length (gold standard) were calculated and statistically analyzed. Results: Differences between lengths measured with the 3D Endo and the Raypex 6 compared with the gold standard showed no significant differences (P = 0.879). Mean differences were 0.37 mm versus 0.35 mm in the maxillary molars, and 0.30 mm versus 0.31 mm in the mandibular molars. A total of 75.8% (3D Endo) and 79.1% (Raypex 6) of all measurements were within the limits of ± 0.5 mm. Both methods showed a tendency to result in short measurements (P 0.001). Conclusions: Within the limitations of this study, the 3D Endo software enables an accurate three-dimensional (3D) predetermination of root canal lengths. Keywords: 3D Endo, ERCLMD, CBCT, Raypex 6, root canal length determination

The aim of the present pilot study was to analyze the reliability of interocclusal contact records generated with an intraoral scanner (TRIOS Standard) and an extraoral scanner (Zfx Evolution). Ten patients were selected. The number of occlusal contacts was first determined with the conventional method using 8-µm articulating paper (gold standard) (control). These conventional records were then compared with the intra- and extraoral digital records. Diagnostics tests (sensitivity, specificity, predictive values for positives and negatives), receiver operating characteristic (ROC) curve, and Cohen's kappa coefficient were performed to analyze the data. The kappa index of the extraoral scanner (40.7%) was considered to be 'moderate,' and better than that of the intraoral scanner (26.1%), which was considered to be 'low.' The extraoral scanner showed better results in the diagnostic test and in the ROC curve. The first results suggest that the extraoral scanner is more reliable for recording occlusal contacts than the intraoral scanner. Keywords: occlusal contacts, articulating paper, intraoral scanner, extraoral scanner, digital impressions

This clinical report describes a digital workflow using an intraoral digital impression and cone beam computed tomography (CBCT) volumetric data to create a three-dimensional (3D) virtual model of the dentition, defect area, and soft and hard tissue of a patient who had undergone a hemimaxillectomy. Stereolithography (SLA) 3D printing technology was used to produce a resin mold, from which an obturator prosthesis was fabricated through a conventional technique. Keywords: CBCT, intraoral scanner, 3D printing, obturator

3D imaging in dentistry plays an essential part in diagnostics and treatment planning. To transform digital images into a real object that can be experienced haptically may provide new opportunities to practitioners regarding patient communication, skills training, and treatment planning. Therefore, the aim of this article is to provide a practical guide from 3D imaging to 3D printing using low-cost printers and open source software; the authors used 3D Slicer software and a Meshmixer printer, including the printer's own software. The article presents step-by-step instructions on how to perform rapid prototyping via fused deposition modeling (FDM) and stereolithography (SLA). As an example, we printed the skull of a patient with Saethre-Chotzen syndrome who was undergoing maxillofacial surgery. The protocol explained here should enable the technically interested clinician to produce patient-specific 3D models in-house, prefabricate osteosynthesis plates, and take advantage of the benefits of 3D printing for dentist-patient communication. Keywords: 3D imaging, 3D printing, FDM printing, SLA printing, rapid prototyping, preoperative treatment planning