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Table of Content
01 June 2021, Volume 39 Issue 3
  • Mechanism, prevention, and treatment for medication-related osteonecrosis of the jaws
    Pan Jian, Liu Jiyuan
    West China Journal of Stomatology. 2021, 39(3):  245-254.  doi:10.7518/hxkq.2021.03.001
    Abstract ( 2561 )   HTML ( 523 )   PDF(pc) (4714KB) ( 3503 )   Save
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    The morbidity rate of medication-related osteonecrosis of the jaws (MRONJ) increased rapidly in recent years. Thusfar, the mechanism of MRONJ has no consensus. The possible mechanisms may include bone remodeling inhibition theory, angiogenesis inhibition theory, oral microorganism infection theory, immunosuppression theory, cytotoxicity-targeted oral epithelial cells, microcrack formation of maxillary or mandibular bone, and single nucleotide polymorphism. However, the efficacy of prevention and treatment based on a single mechanism is not ideal. Routine oral examination before MRONJ-related drug treatment, treatment of related dental diseases, and regular oral follow-up during drug treatment are of great significance for the prevention of MRONJ. During the treatment of MRONJ, the stage of MRONJ must be determined accurately, treatment must be standardized in accordance with the guidelines, and personalized adjustments must be made considering the specific conditions of patients. This review aimed to combine the latest research and guidelines for MRONJ and the experiences on the treatment of MRONJ in the Maxillofacial Surgery Department of West China Hospital of Stomatology, Sichuan University, and discuss the strategies to improve the clinical process.

    Comprehensive correction of maxillofacial bone deformity—consideration and combined application of orthognathic surgery and facial contouring surgery
    Zhu Songsong, Li Yunfeng
    West China Journal of Stomatology. 2021, 39(3):  255-259.  doi:10.7518/hxkq.2021.03.002
    Abstract ( 1334 )   HTML ( 203 )   PDF(pc) (2884KB) ( 1593 )   Save
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    The maxillofacial skeleton is the basis of the contour of the face. Orthognathic surgery and facial contouring surgery change jaw tissue and affect facial appearance in different manners. Orthognathic surgery is the main method to correct dental and maxillofacial deformities. It changes the shape of the jaw and improves the occlusal relationship by changing the three-dimensional position of the jaw. Facial contouring surgery mainly adopts the method of “bone reduction”, which changes the “amount”of the jawbone by cutting a part of the bone tissue to improve the facial appearance, generally without changing oral function. The combined use of orthognathic surgery and facial contouring surgery is becoming increasingly common in clinical practice. This also requires oral and maxillofacial surgeons to have a holistic consideration of the comprehensive correction of maxillofacial bone deformity, and to perform comprehensive analysis of jaw deformities and jaw plastic surgery to achieve the most ideal results. The author's team has been engaged in the clinical work of orthognathic surgery and facial contouring surgery and accumulated rich clinical experience in the comprehensive correction of maxillofacial bone deformity. In this article, the indications, treatment goals, treatment modes, treatment methods, and key points in the surgical operations of comprehensive maxillofacial bone surgery were summarized.

    Protective effect of low-level laser irradiation on lipopolysaccharide-mediated inflammatory injury of human periodontal ligament fibroblasts
    Jin Xiaolan, Zhang Yanan, Sun Chengrui, Zou Zhaohui
    West China Journal of Stomatology. 2021, 39(3):  260-266.  doi:10.7518/hxkq.2021.03.003
    Abstract ( 448 )   HTML ( 18 )   PDF(pc) (3316KB) ( 286 )   Save
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    Objective

    To study the effect and mechanism of low-level laser irradiation (LLLI) on lipopolysaccharide (LPS)-induced inflammatory injury of human periodontal ligament fibroblasts (hPDLFs).

    Methods

    hPDLFs were inoculated into well plates and randomly divided into the normal group, LPS group, and LPS+LLLI group. The cells in the normal group were cultured in conventional medium. The hPDLFs in the LPS and LPS+LLLI groups were cultured in RPMI1640 medium containing 1 mg·L-1 LPS. The three subgroups of the LPS+LLLI group were exposed to different LLLI. After 4 days, the cell apoptosis, viability, and intracellular free Ca2+ concentration of each group were measured. The contents of tumor necrosis factor-α (TNF-α), interleukin (IL)-8, IL-1β, and IL-6 were measured by enzyme linked immunosorbent assay (ELISA). Reverse transcription-polymerase chain reaction (RT-PCR) and Western blot were used to detect the expression of matrix metalloproteinase (MMP)-2, MMP-3, and MMP-9 genes and proteins of hPDLFs in each group.

    Results

    Compared with the normal group, the LPS group showed increased apoptosis rate of hPDLFs and intracellular free Ca2+concentration and decreased cell viability (P<0.05). The TNF-α, IL-8, IL-1β, and IL-6 levels were higher in the cell supernatant (P<0.05), and the expression of MMP-2, MMP-3, and MMP-9 genes and proteins of hPDLFs was significantly increased (P<0.05). Compared with the LPS group, the LPS+LLLI group showed significantly decreased apoptosis rate and intracellular free Ca2+ concentration and significantly increased cell viability (P<0.05). The TNF-α, IL-8, IL-1β, and IL-6 levels in the supernatant of cells and the expression of MMP-2, MMP-3, and MMP-9 genes and proteins of hPDLFs were significantly decreased (P<0.05).

    Conclusion

    LLLI has a protective effect on the inflammatory injury of hPDLFs induced by LPS, and the effect is most obvious when the irradiation intensity is 4 J·cm-2.

    Effect of ionizing radiation on the secretion of the paracellular pathway in rat submandibular glands
    Wu Yanhui, Xu Hui, Yao Qingting, Liu Shaohua, YAKUPU Aipiziguli, Lu Lidan, Shi Liang
    West China Journal of Stomatology. 2021, 39(3):  267-273.  doi:10.7518/hxkq.2021.03.004
    Abstract ( 333 )   HTML ( 21 )   PDF(pc) (4159KB) ( 196 )   Save
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    Objective

    This study aims to investigate the effects of ionizing radiation on the secretion of the paracellular pathway in rat submandibular glands (SMGs) and reveal the changes in the tight junction (TJ) protein claudin-4.

    Methods

    A total of 24 Wistar rats were randomly divided into control and irradiation groups. The irradiation groups were further divided into 1, 4, and 12 weeks groups after irradiation. One-time 20 Gy irradiation was given to the SMG area on the experimental side of the irradiation group. At 1, 4, and 12 weeks after irradiation, the secretion of SMGs was measured using the Schirmer's test. The pathological changes in the gland tissues were observed under light microscopy after hematoxylin?eosin (HE) staining. The changes in the TJ ultrastructure were observed under transmission electron microscopy. The immunofluorescence staining and Western blot were used to detect the expression levels of muscarinic acetylcholine M3 receptor, aquaporin 5 (AQP5), and claudin-4 protein.

    Results

    At 1, 4, and 12 weeks after irradiation, the secretion of SMGs in the irradiation group was significantly decreased and lower than that in the control group (P<0.01). At 1 week, the interstitial edema was observed in SMG tissues. Nuclear pyknosis, decreased number of acinar cells, and small focal necrosis with inflammatory infiltration were also observed over time. However, these changes were most evident at 12 weeks after irradiation. In the irradiation group, the TJ ultrastructure of glands at different times appeared to be fuzzy, collapsed, and had decreased electron density. Moreover, the width of TJs was remarkably decreased (P<0.01). The expression levels of M3 and AQP5 were decreased in a time-dependent manner, and the fluorescence intensity was significantly reduced after irradiation. However, the expression levels and fluorescence intensity of claudin-4 were enhanced in different degrees.

    Conclusion

    The changes in the TJ structure, the upregulation of the claudin-4 expression, and the damage in the paracellular pathway were involved in the hyposecretion of SMGs after irradiation.

    Expressions of cytokeratin 14 and proliferating cell nuclear antigen in the Hertwig’s epithelial root sheath of a Vps4b knockout mouse
    Tian Qing, Wang Yingying, Li Qiang, Chen Dong
    West China Journal of Stomatology. 2021, 39(3):  274-278.  doi:10.7518/hxkq.2021.03.005
    Abstract ( 335 )   HTML ( 23 )   PDF(pc) (3537KB) ( 249 )   Save
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    Objective

    The effect of Vps4b gene mutation on the expressions of cytokeratin 14 (CK14) and proliferating cell nuclear antigen (PCNA) in the Hertwig's epithelial root sheath (HERS) is investigated.

    Methods

    The bilateral mandibular tissues of mouse on postnatal days 5, 9, 11, 15, and 19 were removed. The mandibular first molar tissue sections were obtained after paraffin embedding. The CK14 and PCNA expressions in the epithelial root sheath of the normal mouse and Vps4b knockout mouse were compared through immunohistochemistry.

    Results

    On postnatal day 5, the normal mouse began to form HERS and had a strong positive PCNA expression in the HERS cells; on postnatal day 9, the HERS structure was continuous, and PCNA was positive in the HERS cells; on postnatal day 11, a small portion of HERS began to break, and PCNA was weakly positive in the HERS cells; on postnatal day 15, HERS continued to fracture; PCNA was weakly and positively expressed in the HERS cells on the root surface; on postnatal day 19, the tooth root reached normal physiological length, and PCNA was positively expressed in the HERS cells of the terminal part. Similar to the normal mouse, the gene knockout mouse also formed a HERS structure on postnatal day 5. However, HERS began to break on postnatal day 9. On postnatal day 19, only a few fragments of HERS were found on the root surface, and the root development was immature. Moreover, the expression intensity of PCNA in the gene knockout mouse was decreased.

    Conclusion

    The Vps4b gene mutation may change the CK14 and PCNA expressions, leading to abnormal root development.

    Effects of different implant surface properties on the biological behavior of Schwann cells
    Wang Yanying, Gong Ping, Zhang Jian
    West China Journal of Stomatology. 2021, 39(3):  279-285.  doi:10.7518/hxkq.2021.03.006
    Abstract ( 382 )   HTML ( 22 )   PDF(pc) (2990KB) ( 265 )   Save
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    Objective

    This study investigated the effects of different implant surface properties on the biological behavior of Schwann cells.

    Methods

    Schwann cells (SCs) were cultured on three types of implant surfaces including smooth polished (SMO), sand-blasted, large grit, acid-etched (SLA), and chemically-modified SLA (modSLA). At different time points, the morphology and adhesion of SCs on the implant surfaces were observed by scanning electron microscope. Cell proliferation activity was detected by MTT method. The expression levels of nerve growth factor (NGF) and brain-derived neurotrophic factor (BDNF) were detected by enzyme-linked immunosorbent assay. Changes in the mRNA levels of NGF and BDNF were detected by real-time fluorescent quantitative polymerase chain reaction (PCR).

    Results

    SCs adhered, stretched, and proliferated well on the three types of implant surfaces. On the 3rd, 5th, and 7th days, the OD values of the SMO group were higher than those of the SLA group and the modSLA group, and the difference was statistically significant (P<0.05). On the 3rd day, the expression and mRNA levels of NGF and BDNF in the SLA group and the modSLA group were higher than those in the SMO group (P<0.05); in particular, the levels in the modSLA group were higher than those in the SLA group (P<0.05).

    Conclusion

    Different implant surface properties have different effects on the biological behavior of SCs. Proliferation of SCs is significantly promoted by smooth surface, while secretion and gene expression of neurotrophic factors are significantly promoted by modSLA surface at early stage.

    Clinical assessment of pterygoid and anterior implants in the atrophic edentulous maxilla: a retrospective study
    Wu Jin, Liu Kun, Li Ming, Zhu Zhijun, Tang Chunbo
    West China Journal of Stomatology. 2021, 39(3):  286-292.  doi:10.7518/hxkq.2021.03.007
    Abstract ( 776 )   HTML ( 91 )   PDF(pc) (2076KB) ( 953 )   Save
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    Objective

    This study aims to evaluate the short-term clinical outcomes and patient satisfaction of anterior and pterygoid implants in the rehabilitation of edentulous maxilla with posterior atrophy.

    Methods

    Given a minimum follow-up of 1 year, 25 patients with fixed maxillary rehabilitation over anterior and pterygoid implants were enrolled in this retrospective study. The implant survival rates, peri-implant soft tissue status (including probing depth, modified sulcus bleeding index, and plaque index), marginal bone loss, and patient satisfaction were measured.

    Results

    The survival rates for anterior and pterygoid implants at 1-year follow-up were 96.5% and 97.8%, respectively (P>0.05). No statistically significant difference in probing depth, modified sulcus bleeding index, and plaque index was observed between the two types of implants (P>0.05). The marginal bone losses of anterior implants were 0.62 mm± 0.44 mm (mesial) and 0.61 mm± 0.40 mm (distal), and those of pterygoid implants were 0.64 mm± 0.46 mm (mesial) and 0.68 mm± 0.41 mm (distal) mm. These results showed no statistical difference in mesial and distal sites (P>0.05). Patients indicated a high degree of satisfaction with the full-arch prostheses supported by anterior and pterygoid implants.

    Conclusion

    For the edentulous maxilla with posterior atrophy, full-arch fixed prostheses supported by anterior and pterygoid implants has an acceptable short-term clinical outcome and excellent patient satisfaction. It may be considered as a predictable and feasible method for maxillary rehabilitation.

    Application analysis of a modified retroauricular hairline incision in the resection of a benign parotid gland tumor
    Chen Fen, Li Yu, Ke Xing, Wu Pingfan, Guo Lingyan, Lei Zhenge, Tan Weibin, Chen Linlin
    West China Journal of Stomatology. 2021, 39(3):  293-299.  doi:10.7518/hxkq.2021.03.008
    Abstract ( 1121 )   HTML ( 168 )   PDF(pc) (4251KB) ( 1279 )   Save
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    Objective

    This study aimed to evaluate the application value of a modified retroauricular hairline incision and a sternocleidomastoid flap with an inferior pedicle in the resection of benign parotid gland tumors.

    Methods

    Forty-eight patients with benign parotid gland tumors were retrospectively analyzed: 19 cases were included in the experimental group with an improved retroauricular hairline incision and a sternocleidomastoid flap with an inferior pedicle, and 29 cases were assigned in the control group with a modified facelift incision. Operation time, postoperative drainage, postoperative esthetic degree, and incidence of facial nerve paralysis, salivary fistula, and Frey's syndrome were compared.

    Results

    After the esthetic procedure, the average score of the experimental group was higher than that of the control group, and the esthetic effect of the former was better than that of the latter (P<0.05). The incidence of the operation time, facial nerve paralysis, salivary fistula, and Frey's syndrome of both groups had no statistically significant differences (P>0.05).

    Conclusion

    The modified retroauricular hairline incision and sternocleidomastoid flap with an inferior pedicle can be applied to resect benign parotid gland tumors safely. It shows a better cosmetic effect and does not cause obvious postoperative complications. Therefore, it should be promoted for tumor treatments.

    Salivary biochemical indices related to early childhood caries
    Zhang Ying, Jia Songbo, Li Fan, Li Shanshan, Zhang Lijuan, Tan Kaixuan, Lu Jie, Yang Fang
    West China Journal of Stomatology. 2021, 39(3):  300-305.  doi:10.7518/hxkq.2021.03.009
    Abstract ( 385 )   HTML ( 20 )   PDF(pc) (1716KB) ( 511 )   Save
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    Objective

    This study aimed to compare the salivary biochemical indices between caries-free individuals and those with early childhood caries (ECC), and construct a saliva-based caries diagnostic model by analyzing the correlation between salivary biochemical indices and caries severity.

    Methods

    A total of 120 children aged 4-6 years were selected and divided into two groups: individuals with ECC (C group, n=60) and healthy children (H group, n=60). Salivary samples were collected to compare the pH, total protein, and ion concentrations between the two groups. The correlation between the salivary biochemical indices and caries severity was examined, and an ECC diagnostic model was established.

    Results

    The NO3- concentration significantly decreased in the C group, whereas the Cl-, Br-, NH4+, and Mg2+ concentrations significantly increased in the C group (P<0.05). In addition, the salivary caries severity had a significantly negative correlation with the NO3- concentration but had a positive correlation with Br-, Cl-, and NH4+ concentrations (P<0.05). The ECC diagnostic model based on salivary biochemical indices could yield satisfactory results in terms of distinguishing the C and H groups with over 85% accuracy.

    Conclusion

    Salivary biochemical indices can contribute to the diagnosis and risk assessment of ECC.

    Clinical performance of intraoral digital impression for fixed prosthodontics: a Meta-analysis
    Chen Ling, Chen Cheng, Li Zhiyong, Zhang Qi
    West China Journal of Stomatology. 2021, 39(3):  306-312.  doi:10.7518/hxkq.2021.03.010
    Abstract ( 549 )   HTML ( 50 )   PDF(pc) (3672KB) ( 495 )   Save
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    Objective

    To analyze the clinical performance of the intraoral digital impression (IDI) in the fixed prosthodontics.

    Methods

    Databases of Medline (Ovid), EMBASE, Cochrane Central Register of Controlled Trials, and CNKI were searched for randomized controlled trial (RCT) on the use of IDI in fixed prosthodontics until May 2020. Two reviewers independently screened literature, extracted data, and assessed the risk of bias of included studies. A Meta-analysis was conducted when available.

    Results

    Eleven RCTs involving 618 patients were included in this study. A total of 2 and 3 studies had low and high risks of bias, respectively, and other included studies had a medium risk of bias. Results illustrated that the IDI group could shorten the impression-taken time [SMD=-5.63, 95%CI (-11.25, -0.01), P=0.05] and improve the accuracy of the marginal fit [SMD=-0.53, 95%CI (-0.84, -0.22), P=0.000 7] compared with the conventional impression group. However, no significant difference was observed in the internal fit.

    Conclusion

    Evidence indicated a good clinical performance of IDI for fixed prosthodontics. Notably, high-quality studies are expected to further support the conclusion.

    Biological effects of exosome derived from Cal27 on normal human gingival fibroblasts
    Jia Mei’e, Li Zhiyong, Xu Kai, Wang Yiheng, Yu Fei, He Xiangyi
    West China Journal of Stomatology. 2021, 39(3):  313-319.  doi:10.7518/hxkq.2021.03.011
    Abstract ( 396 )   HTML ( 24 )   PDF(pc) (2839KB) ( 660 )   Save
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    Objective

    The proliferation, migration capacity, and expression of activation-related proteins of NHGFs+Cal27-exo were determined by coculturing Cal27 exosome (Cal27-exo) with normal human gingival fibroblasts (NHGFs) to explore the effects of Cal27-exo on the activation and biological behavior of NHGFs.

    Methods

    Cal27-exo was extracted using supercentrifugation, and exosomes were identified using Western blot, transmission electron microscopy (TEM), and particle size detection. Cal27-exo was cocultured with NHGFs to detect the uptake of Cal27-exo by NHGFs, and the proliferation and migration capacity of NHGFs+Cal27-exo were detected using CCK8 and wound healing tests, respectively. The expression levels of NHGF activation-related proteins, i.e., matrix metalloproteinase-9 (MMP-9), fibroblast-activating protein (FAP), alpha smooth muscle actin (αSMA), and transforming growth factor-β (TGF-β), were detected using real-time quantitative polymerase chain reaction (qRT-PCR).

    Results

    Cal27-exo was extracted u-sing supercentrifugation, and Western blot showed the positive expression levels of Alix and CD63. TEM showed that Cal27-exo had a circular double-layer vesicle. The particle size was between 30 and 150 nm. Cal27-exo labeled with PKH67 entered NHGFs after the coculture method. The wound healing test showed that the migration capacity of NHGFs+Cal27-exo was stronger after the scratch compared with that of NHGFs. CCK8 results showed that the proliferation activity of NHGFs+Cal27-exo was enhanced. qRT-PCR results showed that the MMP-9 levels of NHGFs+Cal27-exo were upregulated, whereas the TGF-β and αSMA mRNA levels of NHGFs+Cal27-exo were downregulated (P<0.05).

    Conclusion

    The proliferation and migration ability of NHGFs+Cal27-exo are enhanced, and the mRNA expression of related proteins is changed. Cal27-exo can activate NHGFs, which suggests that Cal27-exo has potential significance in tumor invasion and metastasis.

    Effect of the regulator of G-protein signaling 2 on the proliferation and invasion of oral squamous cell carcinoma cells and its molecular mechanism
    Lin Chengzhong, Liu Zheqi, Zhou Wenkai, Ji Tong, Cao Wei
    West China Journal of Stomatology. 2021, 39(3):  320-327.  doi:10.7518/hxkq.2021.03.012
    Abstract ( 458 )   HTML ( 19 )   PDF(pc) (2843KB) ( 313 )   Save
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    Objective

    This study aims to investigate the effect of the regulator of G-protein signaling 2 (RGS2) on the proliferation and invasion of oral squamous cell carcinoma (OSCC) cells and its potential molecular mechanism. Metho?ds The expression status and clinical significance of RGS2 in head and neck squamous cell carcinomas and matched adjacent normal tissues were evaluated using TCGA database. Three OSCC cell lines (i.e., SCC-9, Cal27, and Fadu) were overexpressed with RGS2, and the effect of RGS2 on cell proliferation and invasion was determined using the Transwell, clone formation, and cell counting kit (CCK)-8 assays. Moreover, the yeast two-hybrid scree-ning and co-immunoprecipitation (Co-IP) assays were conducted to detect the correlation of RGS2, four and a half LIM domains protein 1 (FHL1), and damage DNA-binding protein 1 (DDB1).

    Results

    The expression level of RGS2 in OSCC was significantly lower than that in matched adjacent normal tissues (P=0.023). The high RGS2 expression level was negatively correlated with lymphovascular invasion (P<0.001). After transfection with lentiv-RGS2, the expression of RGS2 was increased, and the invasion and proliferation abilities of OSCC cell lines were evidently inhibited. FHL1 could competitively bind with RGS2, which decreased the integration of DDB1 and RGS2, inhibited the ubiquitination process of RGS2, and maintained the stability of the RGS2 protein.

    Conclusion

    RGS2 plays an important role in the inhibition of OSCC proliferation and invasion. The structure stability of RGS2 is competitively regulated by FHL1 and DDB1.

    Effects of isoprenylcysteine carboxylmethyltransferase silencing on the migration and invasion of tongue squamous cell carcinoma
    Zhou Nan, Chi Zengpeng, Li Wenjian, Zhao Kai, Wang Shaoru, Wang Qimin, Tong Lei, He Zongxuan, Han Hongyu, Wang Ying, Chen Zhenggang
    West China Journal of Stomatology. 2021, 39(3):  328-335.  doi:10.7518/hxkq.2021.03.013
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    Objective

    The effect of isoprenylcysteine carboxymethyltransferase (ICMT) silencing on the migration and invasion of tongue squamous cell carcinoma was investigated by constructing the small interfering RNA (siRNA) of ICMT.

    Methods

    Through liposomal transfection, siRNA was transfected into human tongue squamous cell carcinoma CAL-27 and SCC-4 cells (ICMT-siRNA group) with a negative control group (transfected with NC-siRNA) and a blank control group (transfected with a transfection reagent but not with siRNA). Quantitative real-time polymerase chain reaction was performed to analyze the mRNA expression of ICMT and RhoA in each group of cells after transfection and to measure the silencing efficiency. Western blot was applied to examine the expression levels of ICMT, total RhoA, membrane RhoA, ROCK1, matrix metalloproteinase (MMP)-2, and MMP-9 proteins in each group. The migration and invasion abilities were evaluated via wound healing and Transwell motility assays.

    Results

    After CAL-27 and SCC-4 cells were transfected with ICMT-siRNA, the expression levels of ICMT genes and proteins decreased significantly in the experimental group compared with those in the negative and blank control groups (P<0.05). The mRNA and total protein expression levels of RhoA in the two groups were not significantly different (P>0.05). The expression levels of RhoA membrane protein, ROCK1, MMP-2, and MMP-9 decreased (P<0.05). The migration and invasion abilities were inhibited (P<0.05).

    Conclusion

    The migration and invasion abilities of CAL-27 and SCC-4 cells were reduced significantly after the transfection of ICMT-siRNA, and the involved mechanism might be related to the RhoA-ROCK signaling pathway.

    A randomized controlled study on color stability of tetracycline teeth restored with ceramic veneer
    Shi Shuya, Gu Xiaoyu
    West China Journal of Stomatology. 2021, 39(3):  336-340.  doi:10.7518/hxkq.2021.03.014
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    Objective

    This study aimed to evaluate the color stability of tetracycline teeth restored with ceramic veneers of different thicknesses combined with different resin cement systems after aging.

    Methods

    Twenty patients with tetracycline teeth, including two maxillary central incisors, were selected clinically. The patients were randomly divided into four groups and restored with 0.5 and 0.75 mm ceramic veneers by using a veneer adhesive system, either with light-cured or dual-cured reaction. The color difference (ΔE) values after cementation and 1, 6, 12, and 24 months of use were obtained by quantification of L*, a*, and b* values with a colorimeter. The results were analyzed statistically with two-way ANOVA and Student's t test.

    Results

    The ΔE values of ceramic veneers detected after aging were less than 2.25. The 0.5 mm groups exhibited greater color change than the 0.75 mm-thick veneers (P<0.05). No significant difference was found on the color change of dual- or light-cured resin cements.

    Conclusion

    Resin cements and veneer thickness influence the color of ceramic veneers after aging. Cementation of veneers with either dual- or light-cured resin cements does not affect the long-term color stability of tetracycline teeth differently.

    Effect of ceramic materials on the optical properties of porcelain veneers for tetracycline-stained teeth
    Chen Jin, Xia Qi, Zhang Lingling, Qian Huifen, Li Xingxing
    West China Journal of Stomatology. 2021, 39(3):  341-346.  doi:10.7518/hxkq.2021.03.015
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    Objective

    To analyze the chromatic properties and translucency of porcelain veneers made from different ceramic materials against the background of tetracycline-stained teeth.

    Methods

    Porcelain specimens (A1, A3, B2, B4) measuring 0.50 mm in thickness were prepared by heat-press casting and layering. The L*, a*, and b* values of the specimens against simulated tetracycline tooth and black-and-white backgrounds were measured by a spectrophotometer, and color differences ΔE001 between specimens on simulated tetracycline backgrounds and the backgrounds themselves and ΔE002 between specimens on simulated tetracycline backgrounds and the white background were calculated. The translucent parameter (TP) was also evaluated.

    Results

    The ΔE001 of feldspathic specimens (IPS d.SIGN) with the opaque layer was significantly greater than that of glass ceramic specimens (IPS e.max Press LT), and the ΔE001 of group B4 was consistently greater than those of the other color groups (P<0.05). The ΔE002 values of all feldspathic specimens with the opaque layer were less than 1.25, and the ΔE002 values of the glass ceramic specimens were greater than 2.23. However, no significant difference was observed among the different color groups (P>0.05). The TP values of feldspathic specimens with the opaque layer were significantly lower than those of glass ceramic specimens(P<0.05), but no significant difference was observed among different color groups (P>0.05).

    Conclusion

    When changing the color of tetracycline-stained teeth, 0.50 mm-thick IPS d.SIGN feldspathic veneers with an opaque layer provide better chromatic properties than IPS e.max Press LT glass ceramic veneers. However, the translucency of feldspathic veneers is generally poorer than that of glass ceramic veneers.

    Periodontal treatment of furcation involvement at the mandibular first molar with a follow-up of 27 years
    Su Wenqi, Shi Jiahong, Cheng Yan, Lei Lang, Li Houxuan
    West China Journal of Stomatology. 2021, 39(3):  347-354.  doi:10.7518/hxkq.2021.03.016
    Abstract ( 810 )   HTML ( 79 )   PDF(pc) (5698KB) ( 692 )   Save
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    Due to the complicated anatomical structures in the furcation area of multirooted mandibular first molars, dental hygiene is greatly compromised once the furcation is involved in the periodontitis, leading to the unfavorable prognosis of teeth with furcation involvement. A patient came to a dental office with the chief complaint of “mobile mandibular posterior tooth” 27 years ago. The periapical film showed alveolar bone resorption at the root furcation of the right mandibular first molar. Flap surgery and fine supportive therapy were conducted. The patient was diagnosed with “furcation involvement Class Ⅲ” during a revisit three years ago. Satisfactory and healthy periodontal statuses were observed 2, 9, 24, and 33 months after the periodontal flap surgery plus tunneling procedures. A follow-up of 27 years in the present case demonstrated that a favorable prognosis of furcation involvement can be achieved after adequate periodontal treatment.

    Multifocal eosinophilic granuloma of the jaws with long-term follow-up: a case report
    Si Yuchen, Liu Qian, Hou Haijuan, Huang Ping
    West China Journal of Stomatology. 2021, 39(3):  355-361.  doi:10.7518/hxkq.2021.03.017
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    Eosinophilic granuloma, a rare disease, has various clinical manifestations and no specific X-rays features and is thus easily misdiagnosed. This paper reports a case of multifocal eosinophilic granuloma of jaw with long-term follow-up. The patient initially presented with periodontal tissue destruction.The diagnosis, treatment and prognosis of multifocal eosinophilic granuloma of jaw were discussed in combination with the literature to alert this disease in clinical practice.

    Impacted molar upright with self-made helical spring
    Xu Yanzhe, Li Zhihua
    West China Journal of Stomatology. 2021, 39(3):  362-367.  doi:10.7518/hxkq.2021.03.018
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    With a case of mesial impaction of maxillary first and second molar, the mechanical analysis and clinical applications of a self-made helical spring for the uprighting treatment of mesial impacted molars was introduced.