Aims: The objective of this study was to compare the precision and trueness of full-arch impressions using either a conventional polyvinylsiloxane (PVS) material or 2 intraoral optical scanners. Methods: Full arch impressions were obtained of a reference model using addition silicone impression material (Aquasil Ultra; Dentsply Caulk, Delaware, USA) and two optical scanners (Trios, 3Shape, Copenhagen, Denmark and CEREC Omnicam, Sirona, Wals, Austria). Surface matching software (Geomagic® Control™, 3D Systems©, Rock Hill, SC, USA) was used to superimpose the scans within groups in order to determine the mean deviations (μm) between the scans. The overall mean precision and trueness for each group was calculated and compared statistically using one-way analysis of variance with post-hoc Bonferroni (trueness) and Games-Howell (precision) tests (IBM© SPSS® ver 24, IBM UK Ltd, Portsmouth, England). Qualitative analysis was also carried out from three-dimensional maps of differences between scans. Results: Mean and standard deviations (SD) of precision for conventional, Trios and Omnicam groups were 21.7 (±5.4), 49.9 (±18.3), and 36.5 (±11.12), respectively. Mean and standard deviations (SD) for trueness were 24.3 (±5.7), 87.1 (±7.9), and 80.3 (±12.1) respectively. The conventional impression showed statistically significant improved mean precision (P<.006) and mean trueness (P<.001) compared to both digital impression procedures. There were no statistically significant differences in precision (P=0.153) or trueness (P=0.757) between the digital impressions. The qualitative analysis revealed local deviations along the palatal surfaces of the molars and incisal edges of the anterior teeth in the order of <100μm. Conclusion: Conventional full-arch PVS impressions exhibited improved mean accuracy compared to 2 direct optical scanners. No significant differences were found between the two digital impression methods.

Objectives:The aim of this study was to analyze the possible correlation between using a partial coverage interocclusal plaque and the probability of changes in dental positioning. Methods: this is a transversal study, where twenty patients with temporomandibular muscle dysfunction (tmd) were selected in the city of aracaju-se-brazil, with both gender and aged over 18 years. The clinical examination was carried out by the research diagnostic criteria/tmd, patients were classified according to the subgroup of dysfunctions. Individuals classified as muscular tmd were positioned in the dental chair and submitted to orthodontic button bonding procedures on the buccal surface of the central incisors and on the first molars, in such a way that they served as a guide for overlapping tomographic images. Soon after, the anterior partial device was adapted to the antero-inferior teeth and the patients underwent cone-beam computed tomography. The research participants were instructed to use such a device daily, for eight hours, for a period of eight weeks and, thus, they were submitted to a new tomographic image for later evaluation in three dimensions and measurement of the dental positioning modification, if it occurred. Results: in this study we observe no statistically significant association between the presence of tooth movement and the use of the partial cover plate. Conclusion: according to the results of this study, there was no statistical correlation between the use of the partial-coverage interocclusal plaque and the change in dental positioning for the period evaluated.

There are situations in which intraradicular retainers have to be removed and replaced. The objective of this research was to evaluate the apical seal after the removal of a custom cast post and core with a carbide bur or with an ultrasound apparatus. Twenty five roots of extracted human incisors were used. They were endodontically treated and prepared to receive the posts. The posts and cores were cast with 2 types of dental alloys, CuAlZn and PdAg, and were cemented with zinc phosphate cement. After 24 hours, they were removed using the two above mentioned techniques. Then, the roots had their external surface made impermeable by two layers of cyanoacrylate adhesive, leaving only the cervical area for dye penetration. The teeth were immersed in rhodamine for 24 hours. They were then cut and observed under an optical microscope and analyzed with appropriate software (Imagelab). The results were submitted to ANOVA, and they evidenced that, regarding the alloy factor, PdAg posts presented a larger mean infiltration value (2.23 +/- 0.48 mm) as compared to the posts made of CuAlZn (1.39 +/- 0.48 mm) (p = 0.025). Regarding the technique factor, there was no significant difference (p = 0.9) between the removal of the intraradicular retainer using ultrasound (1.99 +/- 0.62 mm) or using a rotating cutting instrument (1.62 +/- 0.62 mm). Under these experimental conditions, it was possible to conclude that the degree of apical leakage was directly related to the alloy type, and it was present in both techniques used.