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.

"Finding the needle in a haystack": oncologic evaluation of patients treated for LUTS with holmium laser enucleation of the prostate (HoLEP) versus transurethral resection of the prostate (TURP).

PURPOSE: To evaluate oncologic parameters of men with bothersome LUTS undergoing surgical treatment with HoLEP or TURP. METHODS: Five hundred and eighteen patients undergoing HoLEP (n = 289) or TURP (n = 229) were retrospectively analyzed for total PSA, prostate volume, PSA density, history of prostate biopsy, resected prostate weight, and histopathological features. Univariate and multivariate logistic regression models were used to identify independent predictors of incidental PCa (iPCa). RESULTS: Men undergoing HoLEP had a significantly higher total PSA (median 5.5 vs. 2.3 ng/mL) and prostate volume (median 80 vs. 41 cc), and displayed a greater reduction of prostate volume after surgery compared to TURP patients (median 71 vs. 50%; all p < 0.001). With a prevalence of incidental PCa (iPCa) of 15 and 17% for HoLEP and TURP, respectively, the choice of procedure had no influence on the detection of iPCa (p = 0.593). However, a higher rate of false-negative preoperative prostate biopsies was noted among iPCa patients in the HoLEP arm (40 vs. 8%, p = 0.007). In multivariate logistic regression, we identified patient age (OR 1.04; 95% CI 1.01-1.07, p = 0.013) and PSA density (OR 2.13; 95% CI 1.09-4.18, p = 0.028) as independent predictors for the detection of iPCa. CONCLUSIONS: Despite differences in oncologic parameters, the choice of technique had no influence on the detection of iPCa. Increased patient age and higher PSA density were associated with iPCa. A higher rate of false-negative preoperative prostate biopsies was noted in HoLEP patients. Therefore, diagnostic assessment of LUTS patients requires a more adapted approach to exclude malignancy, especially in those with larger prostates.

A questionnaire on the use of digital denture impressions in a preclinical setting.

Since February 2010, intraoral scanning (Lava COS system, 3M ESPE, Seefeld, Germany) has been integrated into the preclinical curriculum at the Department of Prosthodontics of the Justus Liebig University. All students were given a lecture and were trained using a guided scan exercise. After preparing three teeth (mandibular first premolars and mandibular first molar in the 4th quadrant) for cast crowns, the students were asked to scan the maxillary and mandibular teeth. Their acceptance of the new module, "Scanning," was analyzed with the use of a questionnaire (n = 108). The evaluation showed that 63.9% of the students perceived the digital impression to be informative, and had an overall positive opinion of this new digital technology. Concerning the difficulty of the scanning process, approximately 60.2% considered it to be manageable, while 55.6% reported that the magnified view of their preparations improved their understanding of preparing chamfer finish lines. Altogether, the majority of students appreciated this intraoral scanning device as an enhancement of their education. They indicated that this method contributes to a better understanding of crown preparations. In conclusion, the implementation of intraoral scanning seems promising in preclinical education and will be continued in the curriculum.

Effects of temperature and temperature-humidity index on the reproductive performance of sows during summer months under a temperate climate.

Heat stress is known to influence sow reproduction, but it is unknown to which extent under temperate climates. Therefore, the impact of temperature and temperature-humidity index (THI) on the reproductive performance of sows during summer months from 2009 to 2011 were studied. Reproductive parameters of 22 264 inseminations and 21 610 resulting farrowings of 22 German commercial farms were analyzed. Climatic records were available from the nearest weather station. Effects of temperature and THI at different periods of the reproductive cycle were estimated from May to September where temperatures were expected to influence climatic conditions indoors. High temperatures and THI values 5 days pre- and 14 days post-breeding reduced litter size by 0.01 to 0.03 piglets (P < 0.05). Prior to farrowing, the number of liveborn piglets was reduced (P < 0.05) and of stillborns increased with rising climatic variables (P < 0.001). On the day of farrowing, reduced numbers of weaned piglets were observed when temperature and THI values were elevated (P < 0.05), but pre-weaning mortality was not influenced (P > 0.05). In conclusion, even under temperate conditions adverse effects of climatic variables on the reproductive performance of sows are present. Thereby, the number of liveborn piglets can be considered as the most sensitive parameter to heat stress. Considering the impact of climate change and predicted heat waves, strategies to mitigate the impact of heat stress are necessary.

Effects of implant system, impression technique, and impression material on accuracy of the working cast.

PURPOSE: This in vitro study aimed to identify the effects of the implant system, impression technique, and impression material on the transfer accuracy of implant impressions. The null hypothesis tested was that, in vitro and within the parameters of the experiment, the spatial relationship of a working cast to the placement of implants is not related to (1) the implant system, (2) the impression technique, or (3) the impression material. MATERIALS AND METHODS: A steel maxilla was used as a reference model. Six implants of two different implant systems (Standard Plus, Straumann; Semados, Bego) were fixed in the reference model. The target variables were: three-dimensional (3D) shift in all directions, implant axis direction, and rotation. The target variables were assessed using a 3D coordinate measuring machine, and the respective deviations of the plaster models from the nominal values of the reference model were calculated. Two different impression techniques (reposition/pickup) and four impression materials (Aquasil Ultra, Flexitime, Impregum Penta, P2 Magnum 360) were investigated. In all, 80 implant impressions for each implant system were taken. Statistical analysis was performed using multivariate analysis of variance. RESULTS: The implant system significantly influenced the transfer accuracy for most spatial dimensions, including the overall 3D shift and implant axis direction. There was no significant difference between the two implant systems with regard to rotation. Multivariate analysis of variance showed a significant effect on transfer accuracy only for the implant system. CONCLUSIONS: Within the limits of the present study, it can be concluded that the transfer accuracy of the intraoral implant position on the working cast is far more dependent on the implant system than on the selection of a specific impression technique or material.

Influence of two functional complete-denture impression techniques on patient satisfaction: dentist-manipulated versus patient-manipulated.

This preliminary clinical study aimed to identify the impact of two border-molding techniques (dentist-manipulated and patient-manipulated) on patient satisfaction, the occlusal force at denture dislodgment, and number of pressure sores. Salivary flow rate and residual ridge resorption were analyzed as covariates. Thirty-six edentulous patients in need of a relining of their existing maxillary denture were included. After relining, no significant influence of the border-molding technique on any of the variables investigated could be identified. It can be concluded that the impact of the border-molding technique on patient satisfaction and denture function probably has been overestimated in the past.

Factors influencing marginal cavity adaptation of nanofiller containing resin composite restorations.

OBJECTIVES: The aim of this study was to investigate the effects of polymerization contraction, shrinkage stress and Young's modulus of nanofiller containing resin composites on early marginal adaptation of restorations in cavities. METHODS: Six nanofiller containing and two reference resin composites were studied. Marginal gap widths of restorations in cylindrical 4.2mm wide and 1.5mm deep dentin cavities, non-bonded or bonded with a self-etch adhesive, and in Teflon cavities of same dimensions were determined 15 min after irradiation (n=8). Polymerization shrinkage strains were measured using the bonded-disk (n=8) and a strain gage method (n=8). For determination of contraction stress the composites (n=10) were bonded to and cured in Araldit molds using a photoelastic method. Flexural moduli of the restoratives were studied according to ISO specification 4049 (n=5). Statistical analysis was performed with one- and two-way ANOVA, Kruskal-Wallis ANOVA test and post hoc tests (p<0.05). RESULTS: Only two nanofiller composites (Kalore, GC, Japan) and Venus Diamond (Heraeus Kulzer, Germany) showed consistently gap-free margins in bonded dentin cavities. The mean gap widths in non-bonded and in Teflon cavities were 6.1-12.8 and 14.1-25.5 µm, and linearly correlated (r(2)<0.85). Significant linear relationships were observed between strain, stress and marginal gap widths in non-bonded and Teflon cavities (p<0.01). Flexural moduli (15 min) were between 1.66 and 8.63 GPa. SIGNIFICANCE: Marginal cavity adaptation of restorations in bonded dentin cavities reflects complex interactions between adhesive bonding on the one hand, and polymerization contraction strain, stress and elastic modulus, on the other.