Statement of problem. Accurate marginal and internal fit of dental restorations are essential for their long-term success. The fit of zirconia restorations prepared using digital scan systems has not been fully evaluated.Purpose. The purpose of this in vitro study was to compare the marginal and internal fit of 3-unit zirconia frameworks fabricated using direct and indirect digital scans.Material and methods. In a maxillary model, the left first premolar and first molar were prepared to receive 3-unit zirconia fixed dental prostheses. Conventional impressions were made using stock trays and 2-step putty/wash polyvinyl siloxane material and were scanned using laboratory scanner (Conventional Impression-Laboratory scanner [CIL] group). The impressions were then poured, and the stone casts were scanned (Dental Cast-Laboratory scanner [DCL] group). Digital scans were made using TRIOS (TRIOS Intraoral scanner [TRI] group) and CS3600 (CS3600 Intraoral scanner [CSI] group) scanners (n=10). Zirconia copings were designed and milled from presintered blocks and subsequently sintered. Marginal, mid-axial, axio-occlusal, and mid-occlusal discrepancies were measured using the silicone replica technique with stereomicroscopy at ×50 magnification. The data were analyzed using 1-way ANOVA (a=.01).Results. The ANOVA revealed significant differences among the studied groups in terms of all studied characteristics (P.01). Marginal gap was significantly higher in the DCL group (106 ±45 mm) compared with all other groups (P.01). However, no significant differences were observed in marginal gap between the TRI (60 ±15 mm) and CSI (55 ±13 mm) groups (P>.01). Internal gap in the mid-occlusal and axio-occlusal regions were significantly higher in the CIL (238 ±92 mm and 227 ±95 mm) and DCL (248 ±71 mm and 216 ±68 mm) groups than those recorded in the TRI (104 ±27 mm and 126 ±31 mm) and CSI (128 ±16 mm and 147 ±28 mm) groups (P.01). Internal discrepancies in the mid-axial position were similar between the TRI (70 ±15 mm) and CSI (72 ±23 mm) groups (P>.01), but these values were significantly lower than those recorded in the CIL (88 ±31 mm) and DCL (85 ±30 mm) groups (P.01). Conclusions.Within the limitations of this study, zirconia frameworks in the TRI and CSI groups had lower marginal and internal gaps compared with those in the DCL and CIL groups. Marginal gap in all groups was within a clinically acceptable range. (J Prosthet Dent 2020;123:105-12)

This case report describes the oral rehabilitation of a patient with cleidocranial dysplasia who received a removable partial denture along with silicone-based permanent soft liner to improve esthetic and masticatory function. This patient was the candidate of neither implant nor orthodontic treatment due to medical conditions, history of mandible fracture, age, and risk of fracture after mandibular teeth extractions. Cone-beam computed tomography has made it possible to obtain comprehensive information regarding the morphology and positional relationship of impacted supernumerary teeth. Also, proper collaboration between surgeon and prosthodontist helped to achieve significant improvements in patient’s self-esteem, masticatory function, and esthetic.

Background: Glass fiber posts, along with their esthetic properties, may have a better stress distribution than cast posts, Therefore, the aim of the present study was to investigate the effect of glass fiber, casting, titanium, and zirconia posts on stress distribution in maxillary central tooth treated with different amounts of ferrule using finite-element analysis. Materials and Methods: In this experimental study, three-dimensional models of maxillary central incisors that have undergone root canal treatment were designed. Then, the models were divided into four groups according to the type of post (Ni-Cr casting, glass fiber, titanium, and zirconia) used. Zirconia monolithic crowns were used in all the four groups. Ferrule heights were repeated at 0 and 2 mm in all models. Models were entered into COMSOL Metaphysics software. Then, the force of 100 N with the angle of 135° on the palatal surface was applied to the longitudinal axis of the tooth, and the stress distribution in the models was investigated. Results: Maximum stress was observed in the middle third of posts. Stress distribution in glass fiber post was better than zirconia and casting posts. Stress accumulation in models with zirconia, titanium, and casting posts was also found in the site between the middle third and coronal third, whereas in models with glass fiber post, stress accumulation was found between the crown and the cemento-enamel junction. In models without ferrule, stress accumulation was observed in one-third of the coronal, especially in glass fiber posts. Conclusion: The post material and ferrule height affected stress concentration. The stress in the cervical area of the dentin was more for glass fiber post when compared to other posts. The use of glass fiber post in teeth with no ferrule results in lower stress along the post, but greater stress in the simulated tooth region.

Background/Purpose. The biocompatibility and cytotoxicity of formaldehyde and monomer are essential in resin-based denture’s byproducts. This present study was performed to compare the release of formaldehyde and monomer and biocompatibility of three brands of heat-curing acrylic resins, including Ivoclar, Bayer, and Acropars, with different mixing properties and the same processing methods. Materials and Methods. In this experimental in vitro study, 18 samples were fabricated from Ivoclar, Bayer, and Acropars heat-curing acrylic resins (each group consisting of 6 samples). The released formaldehyde and monomer level were measured and registered for 1, 7, and 30 days. Also, methyl methacrylate release from samples was used to test cell cytotoxicity using L-929 murine fibroblast. The data were analyzed with repeated measures, one-way ANOVA, and Kruskal–Wallis tests. Results. For formaldehyde release of 1 day, Ivoclar acrylic resin showed the lowest level, followed by Bayer and Acropars acrylic resins ( P < 0.05 ). On 7 and 30 days, Bayer acrylic resin released the lowest formaldehyde, followed by Ivoclar and Acropars acrylic resins ( P < 0.05 ). Acropars showed the weakest and most significant results regarding biocompatibility and monomer release in all three points of time, respectively ( P < 0.05 ). Conclusion. Acropars acrylic resin showed the most significant formaldehyde and monomer release and least biocompatibility compared to Bayer and Ivoclar for 1, 7, and 30 days; however, after 30 days, all three resins displayed the same amount of formaldehyde release.

Taurodontism is an unusual developmental anomaly that most often affects the permanent molars. It is characterized by an elongated pulp chamber, bifurcation near the apex, and no constriction at the level of cementoenamel junction. Endodontic treatment of a taurodont tooth is complicated and requires special consideration because it is hard to find the orifices, preparation, and obturation of root canals. In this case report, mandibular right first molar (tooth#30) of a 10-year-old boy patient was diagnosed hypertaurodont and endodontically treated with an open apex by placement of mineral trioxide aggregate as an apical plug to seal the end of distal root.