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The properties of ZnO nanofilms on titanium surface by atomic layer deposition

SUN Wangxinyue ; SHU Fei ; ZHANG Zhihao ; CHEN Hong ; DUN Zhiyue ; LYU Weijin ; ZHANG Qinghong ; LIU Mei

STOMATOLOGY.2023;43(2):97-103. doi:10.13591/j.cnki.kqyx.2023.02.001

Objective: To compare and investigate the physicochemical characteristics and antibacterial effect of ZnO nanofilms prepared by atomic layer deposition(ALD) at different deposition cycles. Methods: According to different ALD cycles, four groups were set up (control group, 300, 600 and 1 200 cycles group). Using DEZn and water as precursors, ZnO nanofilms were prepared by ALD on the surface of pure titanium specimens. Surface morphology of the films was observed by scanning electron microscope (SEM); the element composition and crystal type of the films were observed by energy dispersive spectrometer (EDS) and X-Ray Diffraction (XRD); the hydrophilicity and thickness of the films were detected by water contact angle detector and ellipsometer. The cytotoxicity of the films was evaluated by CCK-8 assay. The antibacterial effect against S. aureus in vitro of the films was evaluated by optical density method. Results: The surface morphology of the films was uniform and compact as shown through SEM. The grain size increased with the increase of the number of ALD cycles. EDS results showed that the films were mainly composed of Zn and O elements. XRD results confirmed that the composition of the films was ZnO. Results of water contact angle showed that the films were hydrophobic. The thickness of the films was nanoscale and there was a linear relationship between the thickness and ALD cycles. All experimental groups showed no cytotoxicity. The 1 200 cycles group showed the highest antibacterial rate of 65.9% and 52.3% at 24 and 48 hours respectively, which was the best among all experimental groups. Conclusion The ZnO nanofilms prepared by ALD at different cycles on pure titanium surface are uniform and compact. Thickness of the films increases with the increase of ALD cycles. The films have good biocompatibility and anti-S. aureus effect in vitro. The 1 200 cycles group has the best antibacterial effect.

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Effect of different tips of posteriors in extraction treatment on three-dimensional forces of teeth with clear aligners

FAN Yongjie ; KOU Yating

STOMATOLOGY.2023;43(2):104-109. doi:10.13591/j.cnki.kqyx.2023.02.002

Objective: To investigate the three-dimensional forces in real-time at different tips of the posteriors created by clear aligners on maxillary teeth during en-masse retraction of anteriors after 2 first premolars extraction treatment. Methods: Four groups of maxillary models with different tips of posteriors(T1-upright of posteriors, T2-posteriors with distal inclination of 5°, T3-posteriors with mesial inclination of 5°, T4-posteriors with mesial inclination of 10°) undergoing 0.25 mm en-masse retraction treatment using clear aligners were simulated on a multi-axis force/torque transducer measurement system. When each clear aligner was inserted, a computer connected to the transducer collected and recorded the three-dimensional force of every tooth in real-time. Each group included 12 aligners. Results: Incisors received smaller lingual and extrusive forces; canines received greater distal forces; smaller mesial forces were observed on the posteriors, and molars received greater buccal and extrusive forces in T2,compared with T1,which showed statistically significant differences(P<0.05). Incisors received smaller lingual and extrusive forces; canines received greater distal forces; greater mesial forces were observed on the posteriors, and molars received greater buccal and extrusive forces in T3 and T4,compared with T1,which showed statistically significant differences(P<0.05). Conclusion Posteriors with distal inclination contributed to the torque of the anterior and anchorage of posteriors. In group T2 posterior teeth experienced larger buccal forces and extrusive forces than in group T1. When the posteriors crown inclined mesially, the anterior teeth were more prone to lingual tip and caused overbite. The more mesially inclined the posterior teeth were, the more serious overbite was, and the posterior teeth were more prone to anchorage loss.

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Efficacy of the photon-induced photoacoustic streaming combined with nano-silver solution on Enterococcus faecalis in root canals

CUI Jingwen ; FAN Jianlin

STOMATOLOGY.2023;43(2):110-113. doi:10.13591/j.cnki.kqyx.2023.02.003

Objective: o explore the antibacterial effect of combined use of photon-induced photoacoustic streaming (PIPS) and silver nanoparticles (AgNPs) on Enterococcus faecalis biofilm in root canals. Methods: A total of 36 isolated teeth with single root canal were collected to establish an experimental root canal model of Enterococcus faecalis infection. Samples were randomly divided into six groups and 0.9% NaCl, 2% NaClO, 0.1% AgNPs solutions were used with conventional needle irrigation (CNI) or PIPS for root canals. Colony count method was used to measure the number of Enterococcus faecalis biofilm in root canals before and after treatment, and the percentage of colony count reduction was calculated. Results: The inhibitory effect of Enterococcus faecalis biofilm in all experimental groups was stronger than that in the control group (P<0.05). The decrease amplitude of 0.9% NaCl, 2% NaClO, 0.1% AgNPs assisted with PIPS was greater than that of 0.9% NaCl, 2% NaClO, 0.1% AgNPs assisted with CNI (P<0.05). The decrease in the 0.1% AgNPs assisted with PIPS group was significantly greater than that in the 2% NaClO assisted with PIPS group (P<0.05). Conclusion PIPS-assisted AgNPs solution washing can significantly improve the effect of clearing Enterococcus faecalis biofilm in root canals.

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A comparative study on apical sealing performance between single cone obturation and warm gutta-percha root canal filling

XU Zhangfeng ; ZHANG Hao ; ZHOU Yongqing

STOMATOLOGY.2023;43(2):114-117. doi:10.13591/j.cnki.kqyx.2023.02.004

Objective: To compare the sealing performance of three kinds of sealers AH-Plus, iRoot SP and GuttaFlow2 combined with single cone obturation and warm gutta-percha root canal filling. Methods: Seventy premolars with single root canal were extracted recently and prepped to P# by Waveone gold system after truncating tooth crown. Then they were randomly divided into 6 experimental groups (10 premolars per group) and 2 control groups (5 premolars per group). Single tip filling and warm gutta-percha filling were performed, namely AH-Plus single tip filling group (A1), AH-Plus warm gutta-percha filling group (A2), iRoot SP single tip filling group (B1), iRoot SP warm gutta-percha filling group (B2), GuttaFlow2 single tip filling group (C1), GuttaFlow2 warm gutta-percha group (C2), positive control group (D group) and negative control group (E group). After dye penetration test was performed on the filled teeth, microleakage of root tip was detected by longitudinal section method. Results: A1 group had the largest microleakage value, while B2 group had the smallest microleakage value. There was no statistically significant difference in apical sealing between single-tip filling and hot dental glue filling with the same sealant (P>0.05), and also no statistically significant difference in apical sealing between the three kinds of sealant with the same filling technology (P>0.05). Conclusion None of the three root canal sealers can completely seal the root canal, and there is no significant difference in the sealing effect between single tip filling and warm gutta-percha filling.

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Clinical effects of iRoot BP plus and mineral trioxide aggregate in treatment of apical periodontitis with open apical permanent teeth

LEI Gang ; WEI Xin ; YAN Ming ; ZHOU Lili ; YU Jinhua ; WANG Juan ; WU Jintao

STOMATOLOGY.2023;43(2):118-124. doi: 10.13591/j.cnki.kqyx.2023.02.005

Objective: To analyze and evaluate the clinical application effect of bioceramic material mineral trioxide aggregate and iRoot BP plus on the formation of apical barrier in adult teeth with incomplete apical foramen. Methods: A total of 200 permanent teeth with apical periodontitis whose apical foramen were not closed were randomly divided into two groups, and the apical barrier was prepared with MTA and iRoot BP plus, respectively. The operation time of MTA and iRoot BP plus and effects of different types of apical foramen destruction, lesion range of apical area, the filling of apical area and patients' age on the treatment success rate was analyzed and compared. Results: The operation time of preparing apical barrier in iRoot BP plus group was shorter than that in MTA group, and the difference was statistically significant (P<0.05). However, different types of apical foramen destruction, lesion scope of apical area, filling of apical area and patients' age had no effect on the treatment success rate of the two groups (P>0.05). Conclusion The clinical effects of MTA and iRoot BP plus in the treatment of apical periodontitis of permanent teeth with unclosed apical foramen are similar, but the operation performance of iRoot BP plus is better.

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Study on clinical efficacy of a 3D model based on crown-root integration in clear aligners

YANG Jintao ; FAN Dian ; SU Ming ; SHAN Danni ; ZHENG Pengpeng ; CHEN Hongyan ; YANG Xinyu ; ZHANG Liang

STOMATOLOGY.2023;43(2):125-129. doi:10.13591/j.cnki.kqyx.2023.02.006

Objective: To evaluate the clinical effect of clear aligners in the anterior region in non-extraction cases by establishing a three-dimensional model of crown-root fusion to guide clinical application. Methods: Eleven patients visiting the orthodontic department of Xuzhou Stomatological Hospital from December 2020 to December 2021 were collected, and the orthodontic plan was designed using Maestro 3D Dental Studio scheduling software to obtain the expected three-dimensional model of the patient's orthodontic treatment result. CBCT, intraoral scan, and 3D reconstruction software were used to create a postoperative model of the patient. The crown and root data were aligned in Geomagic Studio 2014, and differences in torque and axial inclination between the actual model after treatment and the predicted model of the anterior teeth before treatment were compared in 3-matic. Results: The actual torque angles of the anterior teeth were all smaller than the predicted angles before treatment, with the highest realization rate of 77.55% for lateral incisors and the lowest of 60.70% for central incisors; the actual axial inclination angles of the anterior teeth were also smaller than the predicted angles before treatment, with the highest realization rate of 81.49% for central incisors and the lowest of 74.95% for cuspids. Conclusion A digital model of crown-root integration based on a combination of 3D reconstruction and intraoral scanning techniques is advantageous in assessing the efficacy of clear aligners. In non-extraction cases with clear aligner, the efficiency of movement is higher for small areas of the anterior region.

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Radiological measurement and analysis of trans-inferior alveolar nerve implantation

LIU Jinming ; WU Wenli ; DU Lingyi ; SHEN Ming

STOMATOLOGY.2023;43(2):130-134. doi:10.13591/j.cnki.kqyx.2023.02.007

Objective: To measure the position of the mandibular nerve canal at the mandibular second molar by CBCT image data, analyze the theoretical implantation range of trans-alveolar implantation, and provide a theoretical solution to insufficiency of posterior mandibular bone volume in clinical practice. Methods: Eighty patients with missing mandibular second molars whose vertical bone height of the edentulous area was less than 9 mm were selected for CBCT image measurement, and the distances from the mandibular nerve canal to the buccal cortex, lingual cortex, and alveolar crest were measured to simulate trans-inferior alveolar nerve implantation. The angular range of the buccolingual inclination of the implant was also measured. Results: The distances from the mandibular nerve canal to the buccal cortex, lingual cortex and alveolar crest at the mandibular second molar were(6.913±1.222)mm, (2.859±0.891)mm and (7.991±0.783)mm, respectively. The distance from the mandibular nerve canal to the buccal cortex was significantly greater than that to the lingual cortex. And, 75% of the patients could be implanted by the inferior alveolar nerve. The minimum angle of buccolingual inclination of the simulated implant was 19.360°±7.086°, and the maximum angle was 39.462°±6.924°. Conclusion The mandibular nerve canal at the mandibular second molar is inclined toward the lingual side, which ensures sufficient buccal bone volume. Most patients with severe mandibular atrophy can still adopt implants of conventional length by trans-inferior alveolar nerve implantation to keep a safe distance from the nerve canal.

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Effect of miniscrew-assisted rapid palatal expansion on mandibular position

LEI Qiaoling ; HE Wendan ; LEI Qiyin ; XIONG Peiying ; WANG Zhongdong

STOMATOLOGY.2023;43(2):135-140. doi:10.13591/j.cnki.kqyx.2023.02.008

Objective: To explore the effect of miniscrew-assisted rapid palatal expansion (MARPE) on mandible position in the treatment of adult skeletal Class Ⅰ malocclusion with maxillary transverse deficiency. Methods: In this retrospective study, 20 cases of adult skeletal Class Ⅰ malocclusion with maxillary transverse deficiency treated with MARPE in our hospital from July 2019 to March 2022 were selected as research objects. CBCT data of three time points before treatment (T0), immediately after expansion (T1) and six months after retention (T2) were collected. The head position was standardized and calibrated by Dolphin software, and then mandible landmarks (left and right Condylion, left and right Gonion, Menton) were positioned. The linear distance changes of each landmark relative to the reference plane of coronal plane, axial plane and sagittal plane were measured, which represented the sagittal, vertical and horizontal displacement of mandible respectively. Repeated measurement ANOVA and LSD multiple comparison were used to evaluate the position change of each landmark. Results : The Menton and right Gonion rotated clockwise at T1, and relapsed to the initial position at T2. No lateral displacement of Menton was found. Conclusion When MARPE is used to treat skeletal Class Ⅰ malocclusion with maxillary transverse deficiency, it causes a transient clockwise rotation of the mandiblar. The mandible does not show sagittal, vertical and horizontal position changes in long-term evaluation.

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Research on the effects of tooth demineralization prevention with Duraphat frequently used in orthodontic patients

GUAN Zhaolan ; QIAN Yajing ; WANG Wei

STOMATOLOGY.2023;43(2):141-144. doi:10.13591/j.cnki.kqyx.2023.02.009

Objective: To investigate the effect of frequently used Duraphaton preventing dental demineralization of patients with fixed orthodontic appliances. Methods: A total of 50 orthodontic patients wearing fixed appliances at Department of orthodontics, Affiliated Stomatological Hospital, Nanjing Medical University from June to December 2021 were selected as study subjects by convenient sampling method. They were then randomly divided into experimental group and control group according to random numbers. The experimental group received high-frequency fluoride treatment for unilateral maxillary lateral incisors and no treatment on the contralateral side. Meanwhile, the control group received placebo treatment for unilateral maxillary lateral incisors and no treatment on the contralateral side. Each patient was followed up for 6 months. The initial and final photographs of patients' maxillary lateral incisors were observed and scored to determine the mean demineralization progression index for each group. Results: The difference in mean demineralization progression index was statistically significant when comparing different groups(P<0.05), and the lowest incidence of demineralization was reported in the Duraphattreated group (0.960±0.465), followed respectively by the fluoride-free control group (1.213±0.713), the placebo control group (1.267±0.720) and the placebo treatment group (1.307±0.713). Conclusion High frequency use of Duraphatis is effective in reducing the incidence of demineralization in patients with fixed orthodontic appliances.

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Periodontal therapy for stage Ⅳ grade C generalized periodontitis: A case report of 7-year follow-up

DAI Anna ; DING Peihui

STOMATOLOGY.2023;43(2):145-152. doi:10.13591/j.cnki.kqyx.2023.02.010

Periodontal disease is individual-specific and site-specific. Therefore, the periodontal sequence treatment plan should not only base on the patient's condition and disease progression, but also take local conditions into account. This paper reports the whole periodontal therapy of a young patient with stage Ⅳ grade C generalized periodontitis with longitude observation of 7 years. We analyze the factors between extraction and maintenance of hopeless teeth from individual-specific and site-specific perspectives. We also discuss the importance of keratinized mucosa around implants in order to provide reference for the treatment of periodontitis.

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