Objective:  To measure and analyse noise levels in the learning–teaching activities at the Dental School of the University of Porto (Portugal).Materials and methods:  Sound levels were measured in five different practice areas and laboratories, selected as representative of a variety of learning–teaching activities. The noise levels were determined using a precision sound level meter that was positioned at ear level and at 1 m distance from the operator.Results:  The noise levels registered vary between 60 and 99 dB(A) and are similar to the data of other international studies. The results recorded differences in sound levels when the equipment was merely turned on and during cutting operations. Differences between brand new and used equipment were also noted. It appears that hearing damage risk may be lesser amongst dentists who use brand new equipment.Conclusion:  The noise levels detected in this study are considered to be close to the limit of risk of hearing loss.

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. 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. 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. 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.

The objective of this in vitro study is to evaluate and compare the precision of digital impressions obtained using intraoral scanners and photogrammetry devices for full-arch implant-supported oral rehabilitation. Three reference models were created with various spatial distributions of Straumann implants, according to the Caramês I Classification: (i) option A with six implants; (ii) option B with four implants; and (iii) option C with four implants. Thirty digital impressions were taken for each of the reference models: ten with the Intraoral 3Shape Trios 3 scanner, ten with the Medit i500 intraoral scanner, and ten with the PIC Dental photogrammetry device. Intra-group best-fit overlaps were performed between the virtual models obtained, and accuracy was evaluated using root mean square (RMS) values. A significance level of p = 0.05 was defined. Mean values were statistically analyzed using the Kruskal–Wallis test. All scanners studied showed high precision, with RMS values similar for each implant distribution. The PIC Dental photogrammetry device demonstrated the best results for the CCI A and B distributions, with mean values of 11.28 µm and 14.44 µm, respectively. For the CCI C distribution, the 3Shape Trios 3 scanner achieved the best result, with a mean value of 5.96 µm. Among all devices, the implant distribution showing the highest RMS values was the CCI B, with mean values between 14.44 µm and 16.96 µm. The PIC Dental device was the only method that did not exhibit statistically significant differences in RMS values across the different distributions studied, indicating that its performance is unaffected by distribution variations. No statistically significant differences (p < 0.05) were observed in the RMS values among the three types of scanners. Overall, a smaller number of implants and closer distribution between them resulted in improved precision for digital impressions in full-arch implant rehabilitation.