Accuracy of Silicone Impressions and Stone Models Using Two Laboratory Scanners: A 3D Evaluation.

PURPOSE: To evaluate the in vitro accuracy of impressions obtained with two silicone and corresponding stone models using two laboratory scanners. MATERIALS AND METHODS: A master model with synthetic resin teeth with two single-unit crown preparations was created and scanned using a 12-megapixel scanner. Five conventional impressions of the physical model were prepared with different silicone impression systems (Zhermack and Coltene) using the double-mix technique and poured with gypsum. The impressions and stone models obtained were scanned using two extraoral scanning systems (Identica T500, Medit; S600 ARTI, Zirkonzahn). All best-fit superimpositions of the teeth areas were conducted between the master model and the scans of the impressions and models obtained with the two scanners. A P < .05 level was considered significant. RESULTS: The Identica T500 Medit scanner showed an accuracy of 102.34 (89.67, 115.01) µm for Coltene silicone and 79.51 (67.82, 91.21) µm for Zhermack silicone, while the S600 ARTI Zirkonzhan scanner presented 110.79 (98.24, 123.33) µm and 91.91 (81.29, 102.54) µm, respectively, with significant differences between scanners for Zhermack silicone (P = .008) and for the corresponding stone models (P = .002). Zhermack silicone presented overall discrepancies lower than Coltene silicone, with statistically significant differences in both scanners analyzed (P < .001; P = .017). However, the discrepancies found were within clinically acceptable values. With the Zirkonzahn scanner, discrepancies found in the Zhermack impressions were lower than in the corresponding stone models (P < .001). CONCLUSIONS: The direct digitization of silicone impressions with laboratory scanners presented comparable results to conventional techniques with stone models.

The Thermal Influence of Oral Rehabilitation on the Cranio-Cervico-Mandibular Complex: A Thermographic Analysis.

PURPOSE: Assess the thermal effect of prosthodontic treatment on the cranio-cervico-mandibular complex using infrared thermography. METHODS: The treatment group was composed of adults of both sexes who underwent a prosthodontic treatment in which at least posterior occlusal contacts were added and/or the vertical dimension of occlusion was reestablished. The control group (CG) was constituted of adult subjects of both sexes, with no more than a single missing posterior tooth, excluding third molars. Thermograms were taken of the treatment group with a Flir i7 IR camera both before oral rehabilitation (TGB; n = 33) and two months after treatment was concluded (TGA; n = 19). CG (n = 33) had only one occasion for data acquisition. RESULTS: Statistically significant differences were found when the thermal difference (ΔT) and the health status of the orbicularis oris muscle were compared between the TGB and the TGA groups (p = 0.020 and p = 0.003, respectively). By comparing the health status of the masseter muscle between the CG and TGB, statistically significant differences were also observed (p = 0.030). CONCLUSION: A prosthodontic treatment appears to have a minimum or null effect on the ΔT and/or on the health status of the TMJ and the temporal muscle. In contrast, orbicularis oris muscles exhibited significant thermal variations.

Students' self-confidence and perceived quality of prosthodontics education: A study in the Faculty of Dental Medicine of the University of Porto.

INTRODUCTION: Oral rehabilitation with removable dentures (RDs) is still a viable choice for the edentulous population. Fostering students' confidence in prosthodontic procedures should be a major concern in dental schools. This study has three purposes: (a) to measure the self-reported confidence levels of undergraduate dental students when performing removable prosthodontic treatments; (b) to evaluate the students' perceived quality of removable prosthodontics education; and (c) to assess the students' suggestions to improve removable prosthodontics education. MATERIALS AND METHODS: An anonymous questionnaire was delivered to third-, fourth- and fifth-year students of the Faculty of Dental Medicine of the University of Porto (FMDUP) (n = 176). Data from quantitative questions were statistically analysed with IBM SPSS Statistics for Windows (V.24.0), whilst qualitative data were clustered into topics and analysed in Excel. RESULTS: With a 100% response rate, most students felt "confident" and "very confident" in RD clinical procedures. Overall, the 5th-year students had higher confidence than 4th-year ones, except when surveying diagnostic casts. Our findings also revealed that students considered the removable prosthodontics education "Good" and "Very good," and their main suggestions were related to increasing the time allocated to clinical practice. CONCLUSIONS: Students' confidence in carrying out removable prosthodontic procedures grew as they progressed through the course. Overall, the students' evaluation of the quality of prosthodontics education was positive, and their main suggestion to improve their confidence levels was increasing the clinical experience.

The role of IL-1 gene polymorphisms (IL1A, IL1B, and IL1RN) as a risk factor in unsuccessful implants retaining overdentures.

PURPOSE: Implant-supported overdentures are an alternative predictable rehabilitation method that has a high impact on improving the patient's quality of life. However, some biological complications may interfere with the maintenance and survival of these overdenture implants. The goal of this article was to assess the factors that affect peri-implant success, through a hypothetical prediction model for biological complications of implant overdentures. METHODS: A retrospective observational, prevalence study was conducted in 58 edentulous Caucasian patients rehabilitated with implant overdentures. A total of 229 implants were included in the study. Anamnestic, clinical, and implant-related parameters were collected and recorded in a single database. "Patient" was chosen as the unit of analysis, and a complete screening protocol was established. The data analytical study included assessing the odds ratio, concerning the presence or absence of a particular risk factor, by using binary logistic regression modeling. Probability values (p values) inferior to 0.05 were considered as representing statistically significant evidence. RESULTS: The performed prediction model included the following variables: mean probing depth, metal exposure, IL1B_allele2, maxillary edentulousness, and Fusobacterium nucleatum. The F. nucleatum showed significant association with the outcome. Introducing a negative coefficient appeared to prevent complications or even boost the biological defense when associated with other factors. CONCLUSIONS: The prediction model developed in this study could serve as a basis for further improved models that would assist clinicians in the daily diagnosis and treatment planning practice of oral rehabilitation with implant overdentures.