The shaping ability of the BR, PTN and GN NiTi file systems was equally effective. All instrumentation systems prepared curved root canal systems with no evidence of undesirable changes in 3D parameters or significant shaping errors.

Introduction Due to COVID‐19, innovative, virtual educational methods are being developed to provide students with learning experiences comparable to established clinical practices. Our objective was to produce the Periodontal Senior Case Clinical Challenge (PSCCC) that would provide fourth‐year students an alternative for senior case presentations and would be a formative assessment for which student opinions would be provided and analysed. The PSCCC would utilise an online, case‐based, written, clinical assessment and follow‐up, structured discussion to challenge students to demonstrate ability to apply didactic periodontal knowledge to patient‐based experiences. We hypothesised the PSCCC would provide effective learning and a formative assessment. Material and Methods Relevant didactic resources were distributed to 48 students for independent review. The PSCCC was delivered in two sections, (1) a case‐based assessment via a virtual classroom with written student responses, and (2) oral discussions conducted via virtual meetings that were moderated and assessed by ten periodontists, with the collaboration of nine residents. A voluntary six‐statement survey was used to evaluate the students’ opinions of the PSCCC. The scores for 75% (36/48) of students who participated were evaluated for statistical and clinical importance. Results The value of our PSCCC was supported by 91.7% (33/36) of the analyses (p < .0008). Discussion The PSCCC was a successful alternative pathway to assess students’ clinical and didactic integrated knowledge in periodontics. It provided a unified vision of treatment of the selected case, building on all aspects of the students’ periodontal education whilst allowing interaction in a simultaneous, three‐tiered educational approach, involving dental students, periodontal residents and faculty. Conclusion In support of our hypothesis, for each of the 6 statements, ≥94.44% (34/36) of the scores given by the students were considered exceptionally strong clinical support for our pedagogical strategy that combines educational resources and can be successfully implemented in other programmes.

Objective. To analyze the need for referral to a specialist and to identify the reasons of referrals among Lithuanian general dental practitioners. Material and methods. Questionnaires were sent to all 2879 Lithuanian dental practitioners registered on the Lithuanian Dental Chamber license registry. The questionnaire was made with multiple-choice answers. Respondents were asked to choose only one category of answer that best fitted their clinical attitude. Questions included in the questionnaire concerned general and specific information regarding the need and main reasons for endodontic referral. Results. Of the 2879 questionnaires mailed, 1532 questionnaires containing useful information were returned. The response rate was 53.2%. Of the 1532 respondents, 1431 were general dental practitioners. Majority (72.1%) of the respondents performed complicated root canal treatment by themselves. Almost half (49.6%) of them would like to refer patients to an endodontist. Two of the reasons, which restricted their decision, were the shortage of endodontists and high cost of the procedures in the specialized clinics. Approximately 19% of the respondents referred patients to an endodontist. The main reasons for referral were fractured instruments (86.6%), dental trauma (83.6%), difficulties in diagnostics (79%) followed by persistent symptoms (78.1%). Conclusion. The findings of the present study suggest that the need for referral of patients to an endodontist among Lithuanian dental practitioners exists. The main reasons for referrals were complications of endodontic treatment, traumatic injuries, difficulties in diagnostic procedures, and persistent symptoms.

The present study evaluated the porosity distribution of BioRoot RCS/single gutta-percha point (BR/SC) and MTA flow (MF) fillings, which were used as plugs for the apical perforation repair in curved canals of extracted mandibular molars using micro-computed tomography (μCT). Forty mesial root canals of mandibular first molars were shaped with ProTaper NEXT X1–X5 files 2 mm beyond the apex to simulate apical perforations that were randomly divided into two groups (n = 20) according to the material and technique used for the apical plug: BR/SC or MF. The specimens were scanned before and after canal filling at an isotropic resolution of 9.9 μm. The volumetric analysis of voids in the apical 5 mm of the fillings was performed. Data were analyzed using one-way ANOVA with Bonferroni correction (p < 0.05). Micro-computed tomography (µCT) evaluation revealed significant differences between the groups in terms of porosity: the total volume and percentage volume of voids was lower in the BR/SC group in comparison with the MF group (p < 0.05), with the predominance of open pores in both groups. Neither of the materials and/or application techniques were able to produce void-free root fillings in the apical region of artificially perforated curved roots of mandibular molars.

Dental implant abutment and prosthetic materials, their surface treatment, and cleaning modalities are important factors for the formation of a peri-implant soft tissue seal and long-term stability of bone around the implant. This study aimed to investigate the influence of a polymeric material surface cleaning method on the surface roughness, water contact angle, and human gingival fibroblasts (HGF) proliferation. Polymeric materials tested: two types of milled polymethylmethacrylate (PMMA-Ker and PMMA-Bre), three-dimensionally (3D) printed polymethylmethacrylate (PMMA-3D), polyetheretherketone (PEEK), and polyetherketoneketone (PEKK). Titanium (Ti) and zirconia oxide ceramics (ZrO-HT) were used as positive controls. A conventional surface cleaning protocol (CCP) was compared to a multi-step research cleaning method (RCP). Application of the RCP method allowed to reduce Sa values in all groups from 0.14–0.28 µm to 0.08–0.17 µm (p < 0.05 in PMMA-Ker and PEEK groups). Moreover, the water contact angle increased in all groups from 74–91° to 83–101° (p < 0.05 in the PEKK group), except ZrO-HT—it was reduced from 98.7 ± 4.5° to 69.9 ± 6.4° (p < 0.05). CCP resulted in higher variability of HGF viability after 48 and 72 h. RCP application led to higher HGF viability in PMMA-3D and PEKK groups after 48 h, but lower for the PMMA-Ker group (p < 0.05). After 72 h, no significant differences in HGF viability between both cleaning methods were observed. It can be concluded that the cleaning method of the polymeric materials affected surface roughness, contact angle, and HGF viability at 48 h.

The better understanding of the clinically important behavioral features of new instrument systems has an important significance for the clinical endodontics. This study aimed to investigate the shaping and centering ability as well as cyclic fatigue resistance of HyFlex CM (CM), HyFlex EDM (EDM) and EdgeFile (EF) thermally treated nickel–titanium (NiTi) endodontic instrument systems. Sixty curved root canals of the mesial roots of mandibular molars were randomly assigned into three groups (n = 20) and shaped using CM, EDM and EF files up to the size 40 and taper 04 of the instruments. µCT scanning of the specimens before and after preparation was performed and the morphometric 2D and 3D parameters were evaluated in the apical, middle and coronal thirds of root canals. In each group, 40.04 instruments (n = 20) were subjected to the cyclic fatigue resistance test in artificial root canals at 37 °C temperature until fractures occurred, and the number of cycles to failure (NCF) was calculated. The fractographic analysis was performed using a scanning electron microscope, evaluating topographic features and surface profiles of the separated instruments. The one-way analysis of variance with post hoc Tuckey’s test was used for statistical analysis of the data; the significance level was set at 5%. All systems prepared the comparable percentage of root canal surface with the similar magnitude of canal transportation in all root thirds (p > 0.05), but demonstrated significantly different resistance to cyclic fatigue (p < 0.05). The most resistant to fracture was EF, followed by EDM and CM. The length of the fractured fragments was not significantly different between the groups, and fractographic analysis by SEM detected the typical topographic features of separated thermally treated NiTi instrument surfaces.

The Nanotite implant discs were the most difficult to disinfect, likely because of their chemical and physical properties. Citric acid and tetracycline were most effective for disinfecting the Osseotite implant discs, and further clinical research is needed to verify these effects in vivo. The Nd:YAG laser was the weakest disinfection method, and it is not recommended for disinfecting implant surfaces until its effectiveness is improved.

The aim of this study was to investigate the shaping ability and cyclic fatigue resistance of Genius (GN) and WaveOne (WO) nickel-titanium (NiTi) instruments. Forty mesial root canals of mandibular molars were randomly divided into two groups, according to the instrument system used for root canal preparation (n = 20): GN and WO. Root canals were prepared to the full working length using the crown-down technique, with up to 40.04 instruments for GN group and 40.08 instruments for WO group. Specimens were scanned with a µCT before and after instrumentation. The changes in 3D parameters and degree of canal transportation were evaluated in the apical, middle and coronal thirds of root canals. Size 25, taper 0.04 (GN) and 0.08 (WO) instruments (n = 20) were used in simulated root canals until fracturing, and the number of cycles to failure (NCF) was recorded. The fractured files were investigated under a scanning electron microscope to characterize fractured surfaces. Data were analyzed using ANOVA post hoc Tuckey’s tests with the significance level set at 5%. The GN system was able to prepare the higher percentage of the canal surface with less canal transportation in all root canal thirds and displayed the higher resistance to cyclic fatigue in comparison to WO instruments (p < 0.05). However, the length of the fractured segments was not significantly different among the groups; meanwhile, SEM investigations revealed the typical topographic characteristics of fractured surfaces. Hybrid GN instruments demonstrated superior shaping ability and resistance to cyclic fatigue. However, both NiTi instrument systems prepared the root canals with no significant shaping errors, considerable changes in 3D parameters and no significant differences in the topographic appearances of the instrument surfaces after fractures.