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.

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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.

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Background and Aim: Prevention of dental caries and periodontal disease is an important health priority. Oral health instruction can help to achieve this goal. This study sought to assess the effect of a short-term, targeted, well-structured comprehensive oral health instruction on the level of the knowledge and behavior of patients. Materials and Methods: This study was conducted on 120 patients who were randomly divided into two groups of case and control (n=60). The control group received routine oral health instructions, while the case group received a two-session comprehensive, well-structured oral health instruction provided by trained dental hygienists. The level of the knowledge in the two groups was assessed before and after the intervention using a questionnaire. To assess the effect of the instructions on the oral health behavior of the patients, bleeding on probing (BOP) and periodontal pocket depth (PPD) were measured before and after the instructions. Data were analyzed using generalized estimating equations (GEE). Results: The level of knowledge, PPD, and BOP were not significantly different between the two groups at the baseline (P>0.05). There were significant differences in the level of knowledge (P=0.02), PPD (P=0.03), and BOP (P=0.03) between the two groups after the intervention such that the patients in the case group experienced a reduction in PPD by 2 mm, while BOP decreased by 45%, and knowledge was enhanced by 16% in the case group, compared to the control group, two months after the intervention. Conclusion: Well-structured, targeted, comprehensive short-term oral health instructions can greatly enhance the knowledge and change the behavior of patients.

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