Comparison of digitally assessed quality of posterior crown preparations performed with and without previous practice on patient-specific three-dimensional-printed teeth models.

INTRODUCTION: Three-dimensional (3D)-printing technology can provide customizable simulations, but its effects on patient care quality have not been well studied. This study aimed to assess the impact of practicing with patient-specific 3D-printed teeth models on the quality of patients' dental preparations performed by students transitioning to clinical training. Accordingly, the quality of posterior crown preparations was evaluated by objectively analyzing digital scans and grades in two groups: the study group, which practiced beforehand with patient-specific 3D-printed teeth models, and the control group, which did not practice with these models. METHODS: All 78 fourth-year dental students who had just finished their fixed prosthodontics course at the simulation laboratory with training on phantom heads and without previous clinical experience in crown preparations were invited to participate in the study. Sixty-eight agreed to take part and were randomly divided into a study group that practiced crown preparations on 3D-printed models of their own patient's teeth and a control group that did not practice with 3D-printed models and started their clinical work straightforwardly after simulation training. Students completed validated perception questionnaires on self-confidence and clinical skills before and after the protocol, which were compared using a chi-squared test. Crown preparations performed on 3D-printed models and then on patients were digitally scanned and objectively graded by prepCheck software for critical parameters, such as undercuts, taper, and occlusion reduction. Non-parametric tests were used to compare preparations on 3D-printed models and on patients performed by the study group and those on patients made by the control group. RESULTS: Initially, both groups reported similar perceptions of self-confidence and clinical skills levels. The study group significantly improved both aspects after the protocol. Analysis of the scanned preparations demonstrated that the study group removed less tooth structure from actual patients than from the initial 3D-printed models. In contrast, the control group showed excess occlusal clearance in their patients compared to the study group. CONCLUSIONS: Practicing patient-specific 3D-printed teeth before performing procedures clinically appears to enhance preparation quality and minimize unnecessary tooth reduction in early clinical experiences.

Students' and tutors' perceptions of a deliberate simulated practice using patient-specific virtual and three-dimensional printed teeth models: A pilot study.

OBJECTIVE: This pilot study aimed to investigate the perceptions of dental students and their tutors of a deliberate simulated practice using patient-specific virtual and three-dimensional (3D) printed teeth models. This is before they perform their first indirect posterior tooth restoration on their patients. METHODS: Seventy-eight fourth-year dental students from the 2021 Comprehensive Clinic I course at the University of the Andes, Chile, were invited to participate in a deliberate practice protocol. This consisted of digitally scanning their patients' teeth, printing the files three-dimensionally, and loading them into a virtual reality (VR) dental simulator to create patient-specific models. Subsequently, they practiced the same indirect posterior restorations on these models before performing them on their actual patients. Perceptions about students' preparedness to perform tooth preparations before and after the protocol were collected from students and their tutors through surveys. RESULTS: Sixty-three students (43 female) and six clinical tutors (all male) participated in the study. Before practicing with their patient-specific models, most students believed they had the knowledge, practical skills, and self-confidence to perform indirect restorations on their patients. However, after the protocol, most students thought their self-confidence increased and felt better prepared to treat their patients. Most students preferred the 3D-printed models over the VR models to practice but mentioned that it did not feel like drilling dental enamel. Tutors believed that participating students had higher self-confidence when treating their patients and were more autonomous. CONCLUSIONS: This study demonstrated that students and clinical tutors had positive perceptions of practicing with patient-specific virtual and 3D-printed teeth models before students performed their first indirect restorations on their patients.

Effect of macro-design in the primary stability of short and extra-short implants using resonance frequency analysis. An ex vivo study.

OBJECTIVE: This study aimed to determine the effect of macro design in the primary stability of short and extra-short implants using resonance frequency analysis (RFA). MATERIAL AND METHODS: On an ex-vivo model using pig's ribs, we inserted 80 short and extra-short dental implants (20 implants per brand): Biohorizons®(B) 4.6 × 6mm; Intralock®(I) 4.75 × 6.5 mm; Straumann®(S) 4.1 × 4mm; and Tixos®(T) 5 × 5mm. Primary implant stability was measured using an RFA device. We compared mean ISQ values through ANOVA test. RESULTS: Mean ISQ values: B = 73.36 (±3.39); I = 75.13 (±3.88); S = 65.38 (±8.38); T = 72.13 (±11). B and I showed higher ISQ than S (p-value < 0.001). Short (I) showed higher ISQ than extra-short (B,S,T) implants (p-value = 0.001). Tapered (B,I) had higher ISQ than parallel (S,T) implants (p-value < 0.001). There was a moderate positive correlation between ISQ and length (r = 0.52), and a weak correlation with diameter (r = 0.33). DISCUSSION: The final result is a combination of implant design, length, and diameter. Tapered design (B and I) and larger implants (I) showed better primary stability in terms of ISQ values. This information could be beneficial at implant selection in a severely reabsorbed low-quality bone, privileging length (as long as it is safe), and conical walls design.

The occlusal appliance effect on myofascial pain.

There are limited studies about the effects of occlusal appliance (OA) after three months of use. This study aimed to compare myofascial pain (MP) according to RDC/TMD, craniocervical relationships (CR) and masseter and temporalis bilateral electromyographic (EMG) activity, before and after three months of occlusal appliance use. Nineteen patients participated in this study. Cephalometric and RDC/TMD diagnostics were performed previously (baseline) and at the end of the study period (three months). EMG recordings at clinical mandibular rest position (MRP), during swallowing of saliva (SW) and during maximum voluntary clenching (MVC) were performed as follows: after one hour of use of an OA; after three months of using the OA for a minimum of 16 hours each day; and immediately after removal from the mouth. MP was relieved in all patients at the end of the study period. CR did not change significantly between baseline and after removal of the OA at the end of the study period. EMG activity during MRP, SW, and MVC decreased in both muscles after one hour using the OA and maintained the same level for the three-month period. When comparing baseline versus final EMG activity without OA, a significant decrease was only observed in the masseter muscle. The results observed in the present study are relevant to clinicians because they imply that the therapeutic effect of OA does not significantly affect the homeostasis of the craniocervical system.