Printing orientation is one of the printing parameters that affect the properties of three-dimensional (3D)-printed resins. Different printing orientations and directions have been suggested; however, no clear and specific orientations are recommended in the literature in terms of the printing orientation effect on the accuracy and fit of 3D-printed removable dental prostheses. This review aimed to evaluate the effect of printing orientation on the fit and accuracy of 3D-printed removable dental prostheses. The PubMed, Scopus, and Web of Science databases were searched for published articles that investigated the effect of printing orientations on the accuracy and fit of the 3D-printed denture base. Full-length English published articles were searched between January 2010 and December 2023, which examined topics related to printing orientations, building angles, 3D printing, printing technology, accuracy, dimensional changes, internal fit, marginal integrity, marginal discrepancies, trueness, precision, and adaptation. Of the ten included studies, one investigated maxillary and mandibular denture bases, seven assessed maxillary denture bases, and two evaluated mandibular bases. Different printing orientations, ranging from 0° to 315°, were explored, with a higher prevalence of 0°, 45°, and 90°. The included studies utilized stereolithography and digital light processing printing technologies. High accuracy was observed at 45°, followed by 90. Additional struts and bars on the cameo surface increased the accuracy of the 3D-printed denture base. These results shows that printing orientation has a significant effect on the accuracy of 3D-printed resin, with 45° exhibiting the highest accuracy. In addition to the support structure, the density and position can impact the accuracy.
(1) Background: In this study, the efficacy of cone-beam computed tomography (CBCT) in detecting dental posts was compared to periapical radiography. (2) Methods: A retrospective evaluation of 53 patients' periapical radiographs and CBCT images was performed. The presence and type of the intra-canal dental post were initially determined on the periapical images (PA) radiographs' examination and were then compared to the observer's ability to detect the dental post on a CBCT image. The effect of the post's type (metal cast or prefabricated) on its detection on CBCT images was determined. (3) Results: 10.5% of teeth that were identified as having a post on a PA radiograph were not identified as having a post on the CBCT examination (p < 0.05). Approximately 17.6% of teeth that were identified as not having a post on a PA radiograph were identified as having a post on the CBCT examination (p < 0.05). Moreover, 16.3% and 50% of teeth with a prefabricated or cast posts on PA radiographs were falsely identified on the CBCT examination, respectively (p < 0.05). (4) Conclusions: A CBCT image is an insufficient tool for the identification of metal prefabricated and cast posts. A PA image is the recommended radiographic tool for achieving information about the post-endodontic restoration status of teeth candidates for endodontic retreatment in patients with a former CBCT scan.
Purpose: The aim of this article is to analyze the incidence of undiagnosed obstructive sleep apnea (OSA) in patients affected by dento-skeletal malformation. We also evaluated the patterns most affected by the condition and calculated the post surgical changes. Methods: We conducted a retrospective cohort study on 71 patients including 35 men and 36 women. The patients studied were affected by dento-skeletal class II and III malformations and underwent bimaxillary orthognathic surgery in all cases. Patients were evaluated with polysomnography before surgery and at least 6 months after surgery to assess any improvement or worsening of the apnea hypopnea index (AHI) index. Regarding AHI evaluation criteria, an AHI > 5 was considered indicative of OSA, 4 < AHI < 5 was considered borderline and AHI < 4 was considered indicative of non-OSA. We also considered demographic variables like age at the time of intervention and gender, and anatomical variables like the pattern of the dento-skeletal deformity and the presence or absence of maxillary hypoplasia. Qualitative variables were described as absolute and relative frequencies, while quantitative variables were summarized as mean and standard deviation. To quantitatively express the relationship between two variables, the correlation coefficient was calculated. The covariance array was used to evaluate multiple correlations. Results: Our study shows that there is a significant percentage (33%) of patients who undergo orthognathic surgery with an AHI > 5 and also a percentage of patients (11%) who can be considered to be "borderline." It emerges that the pattern most at risk is the one characterized by retruded maxilla and patients with dento-skeletal class II. Considering the post surgical period, the statistical analysis shows that after surgery, only 8% of malformed patients present an AHI > 5, compared to the 20.5% described in the Italian population. Conclusions: In patients who receive orthognathic surgery, the presence of obstructive sleep apnea is significantly higher than in the general population. When planning the surgical correction of a dento-skeletal malformation, the surgeon must aim not only for the esthetics results, but also for proper stomatognathic and respiratory function; this cannot be achieved without taking polysomnography information into account.