Preclinical motor chunking and fine motor skill learning in fixed prosthodontics: Contribution of 3D printing and satisfaction of dental students

INTRODUCTION

In fixed prosthodontics, simulators are essential to students for a progressive transition from preclinical to clinical condition. With the 3D printing technology, we developed resin bars allowing students to better visualise by motor chunking technique. Main objectives of this work were to describe this teaching methodology used in preclinic among different promotions of second, third and fourth dental years and to evaluate students' feedback.

MATERIALS AND METHODS

Two hundred seventy resin strips were digitally designed and printed in resin. All participants from second, third and fourth had to fulfil a User Experience Questionnaire (UEQ) after the preclinical work. The scales of this questionnaire covered the complete impression of the user experience. Both classical aspects of usability (efficiency, insight and reliability) and aspects of user experience (originality, stimulation) were measured.

RESULTS

For the second dental years, 'Attractiveness', 'Stimulation' and 'Novelty' were considered 'Excellent'. For the third dental year, novelty average was considered as 'Excellent'. For the fourth dental year, 'novelty' was considered as 'Good'.

DISCUSSION

The resin plates used in this study are original and stimulating for the students, especially for the second-year dental students who found the exercises useful for their learning. This method can also be used by creating scenarios close to the clinical situations encountered in dentistry departments (more dilapidated teeth, preparation of inlays, post and core, etc.). This 3D printed simulation model is not intended to replace the Frasaco® models but is a complement to the learning process.

Volume of unsupported peri-implant soft tissue over time: A cross-sectional observation study

STATEMENT OF PROBLEM

Supraimplant emergence profile changes have revealed that, when not supported, peri-implant soft tissue collapses. However, this phenomenon has not been described qualitatively and quantitatively in 3 dimensions.

PURPOSE

The purpose of this cross-sectional clinical study was to analyze changes in the supraimplant emergence profile digitally over time when the peri-implant soft tissue was not supported.

MATERIAL AND METHODS

A data set consisting of 16 participants with 16 implants was used. After removal of the healing abutment or the interim restoration, 4 intraoral optical impressions were made successively on the patient to record the supraimplant emergence profile at 4 different times: 0 second (T₀), 30 seconds (T_{0.5 min}), 2 minutes (T_{2 min}), and 5 minutes (T_{5 min}). The supraimplant emergence profile surfaces obtained were closed with a 3D meshing software program (Meshmixer) to obtain the volume of the supraimplant emergence profile at each time. The reference volume at T₀ (Vol T₀) corresponded to the volume created during the mucosal healing phase, which, theoretically, should be preserved for the fabrication of the definitive crown. The different volumes (Vol T_{0.5 min}, Vol T_{2 min}, and Vol T_{5 min}) were compared with Vol T₀ to analyze the volumetric changes, kinetics, and topography of this variation by using a 3D visualization and analysis software program (Avizo). A nonparametric Wilcoxon test for paired samples was used for comparison.

RESULTS

The supraimplant emergence profile volume decreased by an average of 5% at 30 seconds (P<.001), 10% at 2 minutes (P<.001), and 14% at 5 minutes (P<.001).

CONCLUSIONS

The supraimplant emergence profile collapsed significantly in 3D when unsupported for 30 seconds or more.

Incidental Findings in Dental Radiology are Concerning for Family Doctors

Cone Beam Computerized Tomography (CBCT) is an imaging technology increasingly used in dentistry. Depending on the size of the examination area, visualization of anatomical structures outside the indication area may reveal incidental findings (IF). The aims of this systematic review and meta-analysis were to 1) evaluate the frequency, location and different types of incidental findings (IF) revealed during CBCT examinations; 2) identify potential influencing factors such as gender or age; 3) highlight what the family doctor should know about CBCT and the benefits for medical care.

70 retrospective studies were included. 60% of IF are in the naso-oropharyngeal airway and paranasal sinuses. Carotid calcifications were observed with a mean prevalence of 9% CI95% [2-21]). Meta-regression showed a significant association of this prevalence with age, irrespective of gender.

Given the high frequency of IF, with varying severity, the whole medical community is fully involved, and its opinion should be sought to ensure the best possible management for the patients. Physicians may also require CBCT examinations that would have been previously prescribed by a dentist, that may serve to better orientate investigations toward another imaging technique. The family doctor is therefore the dentist’s main interlocutor and the main coordinator of the follow-up of IF.

Assessment of automatic segmentation of teeth using a watershed-based method

OBJECTIVE

Tooth 3D automatic segmentation (AS) is being actively developed in research and clinical fields. Here, we assess the effect of automatic segmentation using a watershed-based method on the accuracy and reproducibility of 3D reconstructions in volumetric measurements by comparing it with a semi-automatic segmentation(SAS) method that has already been validated.

METHODS

The study sample comprised 52 teeth, scanned with micro-CT (41 µm voxel size) and CBCT (76; 200 and 300 µm voxel size). Each tooth was segmented by AS based on a watershed method and by SAS. For all surface reconstructions, volumetric measurements were obtained and analysed statistically. Surfaces were then aligned using the SAS surfaces as the reference. The topography of the geometric discrepancies was displayed by using a colour map allowing the maximum differences to be located.

RESULTS

AS reconstructions showed similar tooth volumes when compared with SAS for the 41 µm voxel size. A difference in volumes was observed, and increased with the voxel size for CBCT data. The maximum differences were mainly found at the cervical margins and incisal edges but the general form was preserved.

CONCLUSION

Micro-CT, a modality used in dental research, provides data that can be segmented automatically, which is timesaving. AS with CBCT data enables the general form of the region of interest to be displayed. However, our AS method can still be used for metrically reliable measurements in the field of clinical dentistry if some manual refinements are applied.