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Construction of a low-pH-sensing system in Streptococcus mutans.

West China Journal of Stomatology.2017;35(3):239-244. doi:10.7518/hxkq.2017.03.003

OBJECTIVETo construct a low-pH-sensing system in Streptococcus mutans (S. mutans) and to visually detect the pH in situ.

METHODSPromoter of ureaseⅠ(PureⅠ) and green fluorescence protein (gfp) DNA fragments were amplified by polymerase chain reaction (PCR) from the genome of Streptococcus salivarius 57.I and S. mutans containing the gfp fragment. The two amplified DNA fragments were ligated together and further integrated into pDL278 to construct the recombinant plasmid pDL278-pureⅠ-gfp. This recombinant plasmid was then transformed into S. mutans UA159 cells. Subsequently, the intensity of the optical density per unit area of the low-pH-sensing system was measured and compared under different pH conditions and different processing times.

RESULTSPureⅠ and gfp DNA fragments were amplified successfully with the correct molecule sizes (450 and 717 bp, respectively). The recombinant plasmid pDL278-pureⅠ-gfp was constructed and further verified by PCR and sequencing. The intensity of the optical density per unit area of the low-pH-sensing system increased with decreasing pH and increasing processing time.

CONCLUSIONSA low-pH-sensing system was constructed successfully in S. mutans. Our research verified that pureⅠ of Streptococcus salivarius can function well in S. mutans as an acid induced promoter, and provided a new method of detecting the pH of plaque biofilms in situ.

Biofilms ; Dental Plaque ; Green Fluorescent Proteins ; Hydrogen-Ion Concentration ; Plasmids ; Promoter Regions, Genetic ; Streptococcus mutans ; Streptococcus salivarius

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Difficulties and misunderstandings of root canal filling.

Chen ZHANG

West China Journal of Stomatology.2017;35(3):232-238. doi:10.7518/hxkq.2017.03.002

Root canal filling is performed as the final and most important procedure of root canal treatment. The superior 3D filling is the key determinant of endodontic success. However, such procedure remains a challenge because of the complexity of the root canal system and the limitation of root canal filling materials and methods. This paper provides an overview of current principles and practices in root canal filling, focusing on advantages, disadvantages and indications. The process errors and countermeasures in various root canal filling methods are also discussed. This review provides guidance and help for clinical and practice to achieve a satisfactory root canal filling and improve root canal treatment outcome.
Dental Pulp Cavity ; Humans ; Root Canal Filling Materials ; Root Canal Obturation ; Root Canal Therapy

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Confusion and solution for vital pulp therapy.

Dingming HUANG ; Qian LU

West China Journal of Stomatology.2017;35(3):227-231. doi:10.7518/hxkq.2017.03.001

Dental pulp tissue plays a role in forming dentin, providing nutrition, conducting pain, and generating protective responses to environmental stimuli. Bacterial infection is the main cause of pulp disease, where histopathological changes are the histological basis for determining the choice of treatment and the evaluation of therapeutic effect. Thus, particular attention should be given to eliminate infection, as well as preserve and maintain pulpal health in teeth that show reversible or limited pulpal injuries. Vital pulp therapy, especially its indications and prognostic factors, has been a research hotspot that often causes confusion among clinicians. In this paper, we briefly introduce the confusion and solution for vital pulp therapy in terms of indications, pulp condition assessment, infection elimination, and capping material selection. In addition, we develop a clinical pathway and an operation normalization of vital pulp therapy to better perform the therapy.
Dental Care ; Dental Pulp ; Dental Pulp Capping ; Dental Pulp Diseases ; Dentin, Secondary ; Humans

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Dental implantation in a patient with Sjögren's syndrome: a case report.

Cuifen LUO ; Guoguang PENG ; Yu

West China Journal of Stomatology.2017;35(1):108-111. doi:10.7518/hxkq.2017.01.018

We reported one case of a patient with Sjögren's syndrome and dental implant. This patient was followed up for more than one year. The patient was diagnosed with Sjögren's syndrome for 5 years and treated with long-term corticosteroid. Four implant-tissue interface hydrophilic implants were placed on 15, 16, 44, and 46 of the mandibular and maxillary areas. After the surgery was completed, the patient was treated with oral antibiotic and "shenggu pills" to prevent infection and glucocorticoid to manage Sjögren's syndrome. Consequently, six implants were placed in other parts of the mandibular and maxillary areas. After more than one year of follow-up, the implants and prosthesis remained stable and had no complications. Cone beam CT reconstruction showed good implant-bone combination.
Dental Implantation ; Dental Implants ; Follow-Up Studies ; Humans ; Mandible ; Maxilla ; Sjogren's Syndrome

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Research progress on a nanodrug delivery system for prevention and control of dental caries and periodontal diseases.

Yaling JIANG ; Mingye FENG

West China Journal of Stomatology.2017;35(1):104-107. doi:10.7518/hxkq.2017.01.017

Dental caries and periodontal diseases are common chronic infectious diseases that cause serious damage to oral health. Bacteria is the primary factor leading to such conditions. As a dental plaque control method, chemotherapeutic agents face serious challenges in dental care because of the specific physiological and anatomical characteristics of the oral cavity. Nanodrug delivery system is a series of new drug delivery systems at nanoscale, and it can target cells, promote sustainedrelease effects, and enhance biodegradation. This review focuses on research progress on nanodrug delivery systems for prevention and control of dental caries and periodontal diseases.
Dental Care ; Dental Caries ; Dental Plaque ; Drug Delivery Systems ; Humans ; Periodontal Diseases

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Research progression of the relationship between integrin α2β1 and drug-induced gingival overgrowth.

Yingzhu KANG ; Shujuan GUO

West China Journal of Stomatology.2017;35(1):99-103. doi:10.7518/hxkq.2017.01.016

Drug-induced gingival overgrowth (DIGO) is characterized by fibrous gingival hyperplasia and increased gingival volume. DIGO is histologically associated with proliferation of cells and deposition of extracellular matrices, particularly collagen. Integrin α2β1 is related to collagen phagocytosis and involved in the occurrence and progression of DIGO. This paper reviews the progress of research on the relationship between integrin α2β1 and DIGO.
Collagen ; Gingiva ; Gingival Overgrowth ; Humans ; Integrin alpha2beta1 ; Phagocytosis

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Accuracy of computer-guided implant placement and influencing factors.

Jinmeng LI ; Guomin OU

West China Journal of Stomatology.2017;35(1):93-98. doi:10.7518/hxkq.2017.01.015

Digital technology is a new trend in implant dentistry and oral medical technology. Stereolithographic surgical guides, which are computer-guided implant placement, have been introduced gradually to the market. Surgeons are attracted to this approach because of it features visualized preoperative planning, simple surgical procedure, flapless implant, and immediate restoration. However, surgeons are concerned about the accuracy and complications of this approach. This review aims to introduce the classification of computer-guided implant placement. The advantages, disadvantages, and accuracy of this approach are also analyzed. Moreover, factors that may affect the outcomes of computer-guided implant placement are determined. Results will provide a reference to surgeons regarding the clinical application of this approach.
Dental Implantation, Endosseous ; Patient Care Planning ; Surgery, Computer-Assisted

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Research on bond durability among different core materials and zirconia ceramic cemented by self-adhesive resin cements.

Xinyu LUO ; Xiangfeng MENG

West China Journal of Stomatology.2017;35(1):89-92. doi:10.7518/hxkq.2017.01.014

OBJECTIVEThis research estimated shear bond durability of zirconia and different substrates cemented by two self-adhesive resin cements (Clearfil SA Luting and RelyX U100) before and after aging conditioning.

METHODSMachined zirconia ceramic discs were cemented with four kinds of core material (cobalt-chromium alloy, flowable composite resin core material, packable composite resin, and dentin) with two self-adhesive resin cements (Clearfil SA Luting and RelyX U100). All specimens were divided into eight test groups, and each test group was divided into two subgroups. Each subgroup was subjected to shear test before and after 10 000 thermal cycles.

RESULTSAll factors (core materials, cements, and thermal cycle) significantly influenced bond durability of zirconia ceramic (P<0.00 1). After 10 000 thermal cycles, significant decrease was not observed in shear bond strength of cobalt-chromium alloy luted with Clearfil SA Luting (P>0.05); observed shear bond strength was significantly higher than those of other substrates (P<0.05). Significantly higher shear bond strength was noted in Clearfil SA Luting luted with cobalt-chromium alloy, flowable composite resin core material, and packable composite resin than that of RelyX U100 (P<0.05). However, significant difference was not observed in shear bond strength of dentin luted with Clearfil SA Luting and RelyX U100 (P>0.05).

CONCLUSIONSDifferent core materials and self-adhesive resin cements can significantly affect bond durability of zirconia ceramic.  .

Adhesives ; Ceramics ; Chromium Alloys ; Composite Resins ; Dental Bonding ; Dental Cementum ; Dentin ; Humans ; Materials Testing ; Resin Cements ; Zirconium

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Cone beam computed tomography evaluation of bifid mandibular canals in the adult population in Sichuan Province.

Li YE ; Yafei CHEN

West China Journal of Stomatology.2017;35(1):82-88. doi:10.7518/hxkq.2017.01.013

OBJECTIVETo investigate the incidence of bifid mandibular canals (BMC), and analyze the types, courses, and anatomic features of the variant canals in the adult population in Sichuan Province.

METHODSFive hundred patients (1 000 hemimandibles) underwent cone beam computed tomography (CBCT) were included in this study. The incidence, bifurcate types and courses of the BMC were evaluated.

RESULTSThe incidence of BMC was 13.8% (69/500) in the study, 9.2% in terms of total hemimandibles. The most frequently type was retromolar canals, followed by the dental and buccolingual type, meanwhile the lowest was the forward type. The mean diameter of the accessory canals was 0.90 mm and the mean length was 9.39 mm.

CONCLUSIONSCBCT used in this study has shown that the incidence of BMC assessed by CBCT was significantly higher than panoramic radiography. Furthermore, CBCT can depict the position, course, size and the branches of the mandibular canals. .

Animals ; Cone-Beam Computed Tomography ; Dental Pulp Cavity ; Humans ; Incidence ; Mandible ; Radiography, Panoramic

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Three-dimensional finite element analyses of the deep wedge-shaped defective premolars restored with different methods.

Ling ZHAO ; Liyuan YANG

West China Journal of Stomatology.2017;35(1):77-81. doi:10.7518/hxkq.2017.01.012

OBJECTIVEThe objective of this paper is to analyze the stress distribution in the deep wedge-shaped defective mandibular first premolars restored with different methods.

METHODSThree-dimensional finite element models of mandibular first premolar with deep wedge-shaped defect were created. The model, which was untreated after root canal treatment, served as the control group. Then, according to different treatment designs, four experimental groups were established as follows: resin filling (A), post restoration after resin filling (B), crown restoration after resin filling (C), and post and crown restoration after resin filling (D). Four different post materials were then chosen for establishing the subgroup models: fiber post (B1, D1), AuPd post (B2, D2), pure Ti post (B3, D3), and CoCr post (B4, D4). A force of 100 N was applied at a 30° angle on the buccal-inclined surface near the top of the buccal cusp. The maximum principal stress and Von Mises stress were investigated using finite element analysis software.

RESULTS1) For the control group, the maximum principal stress and Von Mises stress of the residual dentine were the same as those of the tip of the defect. 2) Compared with the control group, the maximum principal stress and Von Mises stress of groups A, B, C, and D decreased greatly (P<0.05). The maximum principal stress and Von Mises stress of groups C and D with crowns were similar. The maximum principal stress and Von Mises stress of the post-dentine surface of groups B and D with fiber post were less than those in the cast metal post models (P<0.05). 3) The displacement of the buccal cusp of group A was similar to that of the control group (P>0.05) and larger than those in groups B, C, and D (P<0.05).

CONCLUSIONSIt is necessary for deep wedge-shaped defective teeth to be treated with full crowns, but a post is not necessary. If a post is used, fiber post with elastic modulus closer to the dentine is more suitable than metal post. .

Bicuspid ; Crowns ; Dentin ; Finite Element Analysis ; Humans ; Post and Core Technique ; Root Canal Therapy ; Tooth Crown

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