OBJECTIVES: This study aimed to compare the effects of virtual adjustment on occlusal interferences in mandibular posterior single crown and three-unit bridge restorations by using the mandibular movement track and the movement parameters of a virtual articulator. METHODS: Twenty-two participants were recruited. Digital casts of the maxillary and mandibular arches were obtained using an intraoral scanner, and the jaw registration system was used to record the data of the mandibular movement track and the movement parameters of the articulator. Four kinds of restorations with 0.3 mm occlusal interferences were designed with dental design software. In particular, single crowns were designed for teeth 44 and 46, whereas three-unit bridges were designed for teeth 44-46 and 45-47, and the corresponding natural teeth were virtually extracted. Virtual adjustment of the restorations was performed using two dynamic occlusal recordings, namely, the mandibular movement track and the movement parameters of the virtual articulator. A reverse-engineering software was used to measure the root-mean-square of the three-dimensional deviation of the occlusal surfaces between natural teeth and the adjusted restorations. The differences between the two methods of virtual-occlusion adjustment were compared and analyzed. RESULTS: For the same group of restorations, the three-dimensional deviation of the mandibular movement track group were lower than those of the virtual articulator group, and the differences were statistically significant (P<0.05). For the four groups of restorations adjusted by the same method, the three-dimensional deviation of the 46-tooth single crown was the largest and the smallest three-dimensional deviation was that of the 44-tooth single crown. Statistical differences existed between the 44-tooth single crown and the other groups (P<0.05). CONCLUSIONS For the occlusal design of posterior single crown and three-unit bridge, the mandibular movement track could be a more effective approach to virtual occlusal adjustment than the movement parameters of the virtual articulator.
Humans ; Mouth, Edentulous ; Occlusal Adjustment ; Jaw Relation Record ; Dental Articulators ; Software

Objectives: To evaluate the diagnostic consistency of working lengths by observing endodontic files in root canals and periapical subtle structures in digital intraoral radiographs presented in two smartphones, a tablet and a laptop computer. Methods: A dried human skull embedded in an acrylic compound was used for exposing radiographs of the upper and lower second premolars and first molars with two endodontic files (Kerr files size 10 and 15) positioned to the full length of the roots or 1.5 mm short of apexes. A total of 100 radiographs were taken for each of the file sizes. Five observers were asked to assess all the 200 digital radiographs according to a 5-category scale in smartphone A (HUAWEI P9 Plus), smartphjone B (Apple iPhone 7), tablet (Apple iPad 2018) and laptop computer (Lenovo Thinkpad E480), respectively. The gold standard for receiver operating characteristic curve (ROC) analysis was determined with the endodontic Kerr file size 20. A total of 150 roots with files were radiographed, 75 of which with files reaching the radiographic apexes of the respective roots and 75 of which with files 1.5 mm short of the radiographic apexes for each endodontic file size. Results from ROC analysis was analyzed with one-way ANOVA and independent sample t test. Results: For the Kerr file size 10, the area under the ROC curve for laptop, tablet and two smartphones were 0.891±0.037, 0.869±0.037, 0.870±0.017 and 0.849±0.037, while for the Kerr file size 15 the ROC values were 0.957±0.02, 0.961±0.02, 0.961±0.01 and 0.961±0.02, respectively. There were no significant differences for diagnostic accuracy for observing endodontic file positions among digital radiographs presented in the two smartphones, one tablet and one laptop devices (endodontic file size 10: F=1.39, P=0.281; endodontic file size 15: F=0.05, P=0.985). A significant difference was found in the diagnostic accuracy of endodontic file positions between size 10 and 15 files in different display devices (t=-10.65, P<0.001). Conclusions: There was a high diagnostic consistency in the determination of working length and periapical subtle structures of roots by observing digital radiographs displayed on smartphones, tablet and laptop computer.
Dental Instruments ; Dental Pulp Cavity/diagnostic imaging* ; Electronics ; Humans ; Molar ; Observer Variation ; Root Canal Preparation

ABSTRACT In the management of periodontitis patients, periodontal risk assessment (PRA) tool is currently being applied during periodontal review (PR). However, an assessment of risk profiles during examination and diagnosis (E&D) may and would effectively assess and diagnose patients’ periodontal conditions, provide personalised treatment planning, and render an enhanced patient care through periodontal management by risk assessment (PEMBRA). From a retrospective study on selected records of 81 patients treated for chronic periodontitis, the PRA profiles of the patients were evaluated during E&D and two to three months after completion of nonsurgical periodontal therapy (NSPT) during PR. The results were analysed using SPSS version 24 for descriptive statistics. On E&D, the patients presented with 25.9% localised and 74.1% generalised chronic periodontitis. Of these, 2.5% of low-risk patients on E&D increased to 21% during PR signifying an improvement after the treatment. However, the medium-risk patients have a slight increase from 32% to 35%, and patients with a high risk of 62% were reduced to 43%. The improvement of the risk profiles for both low and high-risk groups was mostly contributed by the reduction in the plaque score, percentages of bleeding on probing (BOP), and probing pocket depth (PPD) ≥ 5 mm. This evidence-based evaluation of PRA tool during E&D and PR is important for PEMBRA as it encouraged the clinicians to adopt periodontal management through basic periodontal examination, detailed periodontal charting, radiographic interpretation, tooth per tooth prognosis, diagnosis, and targeted NSPT.
Risk Assessment ; Periodontal Diseases -- diagnosis ; Dental Instruments

Various engine-driven NiTi endodontic files have been indispensable and efficient tools in cleaning and shaping of root canals for practitioners. In this review, we introduce the relative terms and conceptions of NiTi file, including crystal phase composition, the design of the cutting part, types of separation. This review also analysis the main improvement and evolution of different generations of engine-driven nickel-titanium instruments in the past 20 years in the geometric design, manufacturing surface treatment such as electropolishing, thermal treatment, metallurgy. And the variety of motion modes of NiTi files to improve resistance to torsional failure were also discussed. Continuous advancements by the designers, provide better balance between shaping efficiency and resistance to of NiTi systems. In clinical practice an appropriate system should be selected based on the anatomy of the root canal, instrument characteristics, and operators' experience.
Dental Alloys/chemistry* ; Dental Instruments ; Equipment Design ; Nickel/chemistry* ; Root Canal Preparation ; Titanium/chemistry*

OBJECTIVE: To evaluate the three-dimensional (3D) reconstruction accuracy of the intercuspal occlusion (ICO) of the dental casts, by the dental articulator position method, and provide a reference for clinical application. METHODS: The standard dental casts in ICO were mounted on average values articulator, and five pairs of milling resin cylinders were respectively attached to the base of both the casts. 100 μm articulating paper and occlusal record silicone rubber were used to detect the occlusal contact number between the posterior teeth of casts mounted on articulator in ICO. The occlusal contact numbers NA detected by the two methods were calculated simultaneously, as the reference. After the upper and lower casts were scanned separately, and the buccal data of casts in ICO were scanned with the aid of the dental articulator position, registration was carried out utilizing the registration software. Then the digital casts mounted in ICO as well as the buccal occlusal data were saved in standard tessellation language (STL) format. Geomagic Studio 2013 software was used to analyze the contact number NS between digital upper and lower casts by the "deviation analysis" function. The differences were compared between N_S and N_A, to evaluate the sensitivity and positive predict value (PPV) of the model scanner to reproduce the occlusal contact with the aid of dental articulator position. The distance D_R between the centers of the circles at the top surface of the upper and lower corresponding cylinders was obtained by the three-coordinate measuring system Faro Edge, as the reference value. The Geomagic Studio 2013 software was used to construct the cylinders of digital casts and the distance D_M between the centers of the circles at the top surface of the corresponding cylinders were measured, as the test value. The one-sample T test was used to analyze the variable differences between D_M and D_R. RESULTS: The PPV of reproducing the occlusal contact point was 0.76 and sensitivity was 0.81. The distance error of the opposite cylinder was (0.232±0.089) mm. There was no statistical difference between the feature points 5-5', while there were statistical differences between the other feature points. CONCLUSION By the dental articulator position method, the model scanner reproduces the occlusal contact point with high sensitivity and PPV, and that meets clinical needs. Meanwhile, the distance between the feature points is greater than the reference value, which will lead to occlusal disturbance, and require clinical grinding.
Dental Articulators ; Dental Occlusion ; Imaging, Three-Dimensional ; Jaw Relation Record ; Models, Dental ; Software

OBJECTIVE: To establish the workflow of determining the jaw position of repositioning splint with the aid of digital technique, and to evaluate the accuracy of this workflow and compare the accuracy of raising different vertical dimensions in vitro. METHODS: A volunteer was recruited. The data of full-arch scans, cone beam computed tomography (CBCT) image and ultrasonic jaw motion tracking of the volunteer were acquired. The full-arch scans were merged with the CBCT image, which were then matched to the jaw motion tracking reference system. The jaw position of repositioning splint was determined when the anterior teeth opening was 3 mm and the condyle was in centric relation of the fossa in the sagittal plane. A digital repositioning splint was designed in the software based on virtual articulator and fabricated with additive manufacturing technique. After the splint was tried in, another CBCT image was taken and a qualitative analysis was conducted to compare the position of condyle between these two CBCT images. In the in vitro study, standard dental plaster casts with resin ball markers attached to the base were mounted onto a fully adjustable articulator in the intercuspal position. The dental casts were scanned by an extraoral scanner to establish digital models. The ultrasonic jaw motion tracking device was used to obtain simulated jaw movements on the articulator, which was repeated for three times. The digital models and data of jaw movements were merged in one coordination with the aid of bite forks. The jaw position of repositioning splint was determined by adjusting data of jaw movements, each of which was used to determine three vertical jaw positions 4 mm, 5 mm, and 6 mm with the horizontal jaw position of protrusion 2 mm. The virtual articulators with differently adjusted jaw movements were applied in designing repositioning splints, and the final repositioning splints and virtual jaw relationships were exported in STL format. Then the repositioning splints were fabricated with additive manufacturing technique and tried in plaster casts on the mechanical articulator, which were scanned and the jaw relationships on the mechanical articulator were exported later. The virtual jaw relationships and scanned jaw relationships were registered according to lower models and displacement of upper models was calculated. Ball markers were fit to acquire the coordinates of centers and absolute difference values of centers along three coordinating axes X, Y, and Z were calculated. One-way analysis of variance was conducted using SPSS 18.0 software to compare deviations of the three different vertical jaw relationships in two-side test and the significance level was 0.05. RESULTS: With the aid of multi-source data fusion and individualized jaw motion, the clinical workflow of determining jaw position of repositioning splint was preliminarily established. The designed jaw position was realized on the right and the condyle was more inferior than the designed position on the left. Both displacement of the upper models and absolute difference values of centers showed no significant differences (P>0.05) in different vertical jaw dimensions. The displacement of the upper models was (0.25±0.04) mm. The absolute difference values of centers along the three coordinating axes X, Y, and Z were respectively (0.08±0.01) mm, (0.30±0.02) mm, and (0.21±0.04) mm. CONCLUSION A novel method of determining the jaw position of repositioning splint with the aid of digital technique is established. It is proved to be feasible by try-in after multi-data fusion, computer-aided design and computer-aided manufacturing. As is shown in vitro, it is accurate to apply this method in adjusting jaw position. Further clinical trial will be designed to evaluate its clinical effect.
Computer-Aided Design ; Cone-Beam Computed Tomography ; Dental Articulators ; Humans ; Jaw Relation Record ; Occlusal Splints ; Software ; Splints

OBJECTIVES: The purpose of this study was to investigate the correlation of periodontitis with metabolic syndromes and menopause status. METHODS: The 2013 Korea National Health and Nutrition Examination Survey data of 645 postmenopausal and 663 premenopausal women were analyzed using the Pearson's chi-squared test and multiple regression analysis with the Statistical Package for the Social Sciences (PASW statistics) software version 21.0. Metabolic syndromes and community periodontal index (CPI) were analyzed. RESULTS: CPI 3, CPI 4 (P<0.001), and the prevalence of periodontal disease were significantly higher in the postmenopausal group (P<0.001). Periodontal disease was significantly higher (P<0.001) in postmenopausal women not using dental floss (2.69 times), hypertensive postmenopausal women (1.60 times), and premenopausal women with high blood glucose levels (1.67 times). In the multiple logistic regression analysis, after adjusting for age, smoking habit, and alcohol consumption, significant risk factors for periodontal disease were the lack of dental floss use (odds ratio [OR]: 1.83; 95% confidence interval [CI]: 1.26–2.67), menopause (OR: 1.71; 95% CI: 1.22–2.41), and number of metabolic syndromes (when 1 or 2, OR: 2.22 and 95% CI: 1.50–3.29; when 3 or more, OR: 2.22 and 95% CI: 1.58–3.13). CONCLUSIONS: In summary, menopause status is associated with periodontal disease. Therefore, oral health programs for middle-aged women with menopause and metabolic syndromes should be conducted to improve their oral health-related quality of life.
Alcohol Drinking ; Blood Glucose ; Dental Devices, Home Care ; Female ; Humans ; Korea ; Logistic Models ; Menopause ; Nutrition Surveys ; Oral Health ; Periodontal Diseases ; Periodontal Index ; Periodontitis ; Prevalence ; Quality of Life ; Risk Factors ; Smoke ; Smoking ; Social Sciences

OBJECTIVES: The aim of this in vitro study was to evaluate the push-out bond strength of a novel calcium silicate-based root repair material-BIOfactor MTA to root canal dentin in comparison with white MTA-Angelus (Angelus) and Biodentine (Septodont). MATERIALS AND METHODS: The coronal parts of 12 central incisors were removed and the roots were embedded in acrylic resin blocks. Midroot dentin of each sample was horizontally sectioned into 1.1 mm slices and 3 slices were obtained from each root. Three canal-like standardized holes having 1 mm in diameter were created parallel to the root canal on each dentin slice with a diamond bur. The holes were filled with MTA-Angelus, Biodentine, or BIOfactor MTA. Wet gauze was placed over the specimens and samples were stored in an incubator at 37°C for 7 days to allow complete setting. Then samples were subjected to the push-out test method using a universal test machine with the loading speed of 1 mm/min. Data was statistically analyzed using Friedman test and post hoc Wilcoxon signed rank test with Bonferroni correction. RESULTS: There were no significant differences among the push-out bond strength values of MTA-Angelus, Biodentine, and BIOfactor MTA (p > 0.017). Most of the specimens exhibited cohesive failure in all groups, with the highest rate found in Biodentine group. CONCLUSIONS: Based on the results of this study, MTA-Angelus, Biodentine, and BIOfactor MTA showed similar resistances to the push-out testing.
Calcium ; Dental Instruments ; Dental Pulp Cavity ; Dentin ; In Vitro Techniques ; Incisor ; Incubators ; Methods ; Miners ; Pemetrexed

OBJECTIVES: It was the aim of this study to evaluate the effect of cooling water temperature on the temperature changes in the pulp chamber and at the handpiece head during high-speed tooth preparation using an electric handpiece. MATERIALS AND METHODS: Twenty-eight intact human molars received a standardized occlusal preparation for 60 seconds using a diamond bur in an electric handpiece, and one of four treatments were applied that varied in the temperature of cooling water applied (control, with no cooling water, 10°C, 23°C, and 35°C). The temperature changes in the pulp chamber and at the handpiece head were recorded using K-type thermocouples connected to a digital thermometer. RESULTS: The average temperature changes within the pulp chamber and at the handpiece head during preparation increased substantially when no cooling water was applied (6.8°C and 11.0°C, respectively), but decreased significantly when cooling water was added. The most substantial drop in temperature occurred with 10°C water (−16.3°C and −10.2ºC), but reductions were also seen at 23°C (−8.6°C and −4.9°C). With 35°C cooling water, temperatures increased slightly, but still remained lower than the no cooling water group (1.6°C and 6.7ºC). CONCLUSIONS: The temperature changes in the pulp chamber and at the handpiece head were above harmful thresholds when tooth preparation was performed without cooling water. However, cooling water of all temperatures prevented harmful critical temperature changes even though water at 35°C raised temperatures slightly above baseline.
Burns ; Dental Instruments ; Dental Pulp Cavity ; Head ; Humans ; Molar ; Thermometers ; Tooth Preparation ; Tooth ; Water

PURPOSE: Surface finishing of a zirconia restoration is essential after clinical adjustment. Herein, we investigated the effects of a surface finishing protocol for monolithic zirconia on final roughness and bacterial adherence. MATERIALS AND METHODS: Forty-eight disk-shaped monolithic zirconia specimens were fabricated and divided into four groups (n = 12) based on initial surface treatment, finishing, and polishing protocols: diamond bur+polishing bur (DP group), diamond bur+stone grinding bur+polishing bur (DSP group), no diamond bur+polishing bur (NP group), and no diamond bur+stone grinding bur+polishing bur (NSP group). Initial and final surface roughness was measured with a profilometer, and shown using scanning electron microscope. Bacterial adhesion was evaluated by quantifying Streptococcus mutans in the biofilm. Kruskal-Wallis and Mann-Whitney U tests were used to compare results among groups, and two-way analysis of variance was used to evaluate the effects of grinding burs on final roughness (α=.05). RESULTS: The DP group had the highest final Ra value, followed by the DSP, NP, and NSP groups. Use of the stone grinding bur as a coarse-finishing step significantly decreased final Ra values when a diamond bur was used (P < .001). Omission of the stone grinding bur increased biofilm formation on specimen surfaces. Combining a stone grinding bur with silicone polishing burs produced the smallest final biofilm values, regardless of the use of a diamond bur in initial surface treatment. CONCLUSION: Coarse finishing of monolithic zirconia with a stone grinding bur significantly decreased final Ra values and bacterial biofilm formation when surfaces had been roughened by a diamond bur.
Bacterial Adhesion ; Biofilms ; Dental Instruments ; Dental Polishing ; Diamond ; Silicon ; Silicones ; Streptococcus mutans