血链球菌细菌素对伴放线聚集杆菌和白色念珠菌生物膜作用的研究

目的:研究血链球菌细菌素分别对单独培养及混合培养的伴放线聚集杆菌(A.a)和白色念珠菌(C.a)生物膜的最小抑菌浓度(MIC)。利用激光共聚焦显微镜研究血链球菌细菌素对A.a及混合培养的A.a和C.a生物膜活性的影响。方法:通过低温高速离心,细胞破碎,盐析等方法提取血链球细菌素—血链素。采用二倍稀释法,测定血链素对单独和混合培养的A.a及C.a的MIC;血链素作用于A.a及混合培养的A.a和C.a后,利用激光共聚焦显微镜分别在2 h、6 h、12 h、24 h、48 h、72 h观察生物膜活性的变化。结果:血链素对单独培养的A.a的MIC为0.25 g/L;血链素对单独培养的C.a的MIC为0.125 g/L;血链素对混合培养的A.a及C.a的MIC为0.5 g/L。通过激光共聚焦显微镜观察,血链素对A.a生物膜活性有较强的抑制作用,最显著的时间在72 h;血链素对混合培养的A.a及C.a生物膜活性同样具有较强的抑制作用,最显著的时间在48 h。结论:血链素对A.a及混合培养的A.a及C.a生物膜活性均有抑制作用。     

Specific antibodies against Actinobacillus actinomycetemcomitans in serum and saliva of patients with advanced periodontitis

The aim of the present study was to discover any possible correlation between specific antibodies against Actinobacillus actinomycetemcomitans (A.a.) in serum and saliva. The test group consisted of 38 patients aged 31–68 yr (mean 49) with advanced periodontitis. Twenty-nine subjects aged 23–67 yr, without periodontal destruction, formed a control group with a reference level of specific salivary antibodies against A.a. A subgingival plaque sample for culturing A.a. , a specimen of stimulated whole saliva, and a sample of venous blood were taken from each subject of the test group. Specific IgG and IgA antibodies against A.a. were determined from serum and stimulated whole saliva by means of the ELISA test. Fifteen of the patients (39%) had cultivable A.a. Six of the 15 A.a. culture-positive patients and one of the 29 reference subjects exhibited very high antibody titers against A.a. in saliva. Specific IgG and IgA antibodies in saliva correlated highly significantly with the corresponding antibody values in serum among the patients in the test group. It was concluded that among patients with severe adult periodontitis, the less invasive saliva sample has a diagnostic value equal to that of the serum sample concerning specific antibodies against A.a.     

Influence of heat from light curing units and dental composite polymerization on cells in vitro

OBJECTIVES: The aim of the present study was to test the hypothesis that the use of a light curing unit (LCU) with high light power would result in a higher temperature and therefore a statistically significant lower number of living human gingiva fibroblasts within a pulp chamber model than the use of a light emitting diode (LED) LCU. MATERIALS AND METHODS: The composites Admira, Grandio, Filtek Supreme and Filtek Z250 were polymerized with the LCUs Swiss Master Light, Optilux 501 and an LED LCU prototype in a mould on top of a pulp chamber model. The temperature was recorded within the pulp chamber with a thermocouple. The cytotoxicity of the polymerized samples was tested by using the MTT test. RESULTS: In general there was no considerable difference in the temperature increase within the pulp chamber model for the different LCUs and composites. There was no statistically significant difference in the cell number (p=0.3767) when the different LCUs were used. CONCLUSIONS: Using a high power halogen LCU for a short time or a standard halogen or LED LCU for a longer time did not result in a considerable difference in the temperature increase or the number of living cells within a pulp chamber model. This study indicates not only that the temperature may have an effect on the living cells, but also that cells may be negatively affected by the unpolymerized composite or light of the LCUs.     

Use of Cone-beam Computed Tomography as a Critical Component in the Diagnosis of an Infected Nasopalatine Duct Cyst Mimicking Chronic Apical Abscess: A Case Report

Nasopalatine duct cysts (NPDCs) and other nonodontogenic lesions of the oral cavity may mimic odontogenic pathoses. We present a case of a 22-year-old man with a history of dental trauma and a lesion displaying the typical clinical and radiographic signs of a chronic apical abscess— a buccal sinus tract that was traced to a radiolucent area in the periapex of a maxillary central incisor. A comprehensive diagnostic process that included a cone-beam computed tomographic scan and a histopathologic examination of the lesion after complete enucleation led to the final diagnosis of an infected NPDC. The adjacent tooth was vital at the 1-year posttreatment follow-up, and a radiograph demonstrated complete healing of the periradicular structures. This case demonstrates the ability of NPDCs to present clinical and radiographic signs similar to apical inflammatory lesions and the need for a meticulous diagnostic process in order to avoid unnecessary endodontic intervention. The article also discusses the differential diagnoses of nonodontogenic lesions in the premaxillary area.     

Incorporation of channel-forming peptides in a Hg-supported lipid bilayer

The channel-forming peptides gramicidin and alamethicin were incorporated in a mercury-supported lipid bilayer composed of a tethered thiolipid monolayer with a self-assembled dioleoylphosphatidylcholine monolayer on top of it. The thiolipid consists of a hexapeptide chain with a high tendency to form a 3₁₀-helical structure, which terminates at the N-terminus end with a sulfydryl group for anchoring to the metal while the C-terminus end is covalently linked to the polar head of dimyristolylphosphatidylethanolamine. The hexapeptide moiety has two triethyleneoxy side chains that impart a satisfactory hydrophilicity and are intended to keep the anchored thiolpeptide chains sufficiently apart, so as to accommodate water molecules and inorganic ions and to create a suitable environment for the incorporation of integral proteins. Changes in the conductance of this biomimetic membrane following the incorporation of gramicidin and alamethicin were detected by impedance spectroscopy. The surface dipole potential of the hexapeptide chain and the transmembrane potential of the lipid bilayer were estimated by using a simple electrostatic model of the mercury|solution interphase.     

Odontogenic keratocyst in maxillary sinus with invasive behaviour

Odontogenic keratocyst is a cystic lesion characterized by a high rate of recurrence. This report describes a rare case of ciliated epithelium-lined odontogenic keratocyst in the maxilla of a 27-year-old female. Panoramic radiography showed a lytic lesion on the right maxilla associated with an impacted molar tooth. Computerized tomography image revealed the involvement of the lesion with the right maxillary sinus, destroying the sinus floor. Histopathologically, the typical keratinized epithelial-lined cyst of odontogenic keratocyst abruptly changed into a ciliated epithelium, suggesting the fusion of both these epithelia rather a metaplastic transformation. The biological behaviour of odontogenic keratocysts is discussed.     

New insights into the nature of Warthin's tumour

Warthin's tumour is considered heterogeneous as to its pathogenesis with some data supporting a polyclonal origin for the epithelium, implying a non-neoplastic nature. After inconsistent reports, current information from molecular studies suggests that a recurrent t(11;19) and associated CRTC1-MAML2 fusion oncogene characterizes a subset of Warthin's tumours and supports a clonal origin in such cases. CRTC1-MAML2 is also a frequent feature of mucoepidermoid carcinoma. These findings, and the recent reports of Warthin's tumour and co-existent mucoepidermoid carcinoma with common CRTC1-MAML2 expression, provide a morphological and molecular framework for future studies as a basis for a fresh appraisal of the pathogenesis of Warthin's tumour. The underlying molecular basis and the pivotal studies defining such events are discussed.     

Fabrication of a Movable Obturator Following Maxillary Reconstruction with Slit‐Shaped Fenestration

Extensive maxillary resection has generally been reconstructed with free skin flaps. Because drooping of the transferred flap causes instability of the obturator prosthesis, maxillary reconstruction often incorporates a slit‐shaped oronasal fenestration. Although obturator prostheses for edentulous patients are stabilized with the help of oronasal slits, those for dentate patients are unstable because of flap mobility, resulting in a harmful lateral force exerted on the abutment teeth, causing dislodging of the denture. This report evaluates the benefits of a movable obturator prosthesis for a 60‐year‐old dentulous patient with maxillary sinus carcinoma. The patient underwent left‐sided total maxillectomy, and the defect was reconstructed with a slit‐shaped fenestration using a rectus abdominis flap. A conventional obturator prosthesis was inserted; however, drooping of the flap caused instability of the obturator, resulting in nasal regurgitation and fracture of the clasp. To solve this problem, we designed an obturator prosthesis with a movable connection consisting of a ball attachment (patrix) in the metal base and a socket (matrix) in the obturator, which acted as a stress breaker against the harmful force exerted by the flap. Application of this movable obturator prosthesis was a useful solution for a compromising situation created by the surgical procedure. No clinical disorders were observed at the 3‐year follow‐up.     

Network participation for unpromoted female dentists in relation to psychosocial support

Studies have shown that female unpromoted general practice (GP) dentists have a taxing work situation with many problems related to their psychosocial work environment. This study aims to describe: 1) the participation of this group in organized network activity (support groups) in a region (Scania) in Sweden, 2) the sense of support compared with another organization and with a nationwide sample of GP dentists, and 3) the covariation of network participation with support. All unpromoted female dentists within the Public Dental Health Service (PDHS) in Scania received a questionnaire and 94% responded. Those participating in network activity ≥4 times a year constituted 12% of respondents. Cooperation between colleagues was lower than in the nationwide sample. Support from the PDHS was experienced as weak. It was not possible to explain why female unpromoted GP dentists participated ≥4 times a year, while those who felt lonely in their work were to a higher degree participants in a network. Almost 9 out of 10 reported being strengthened by the network both as a person and in a professional role. The female dentist was three times more likely to participate in a network if she had a male head of clinic. The main findings are a paucity of inter‐colleague contact and a lack of association between support and network participation. The many affirmative comments indicated that network participation might be a good coping strategy for unpromoted female GP dentists.     

Fabrication of a hollow obturator as a single unit for management of bilateral subtotal maxillectomy

Prosthetic rehabilitation with an obturator for a total or subtotal maxillectomy patient is a challenging task, as there are little or no residual maxillary structures to depend on for support, retention, and stability of the prosthesis. This clinical report describes the prosthodontic management of a patient operated on for a bilateral subtotal maxillectomy secondary to ameloblastoma of the palate with a closed hollow obturator. The processing technique described in this article to fabricate the hollow obturator is a variation of other well-known techniques. The variation comprises the use of a wax bolus to maintain a predictable internal dimension for a hollow obturator. This technique allows fabrication of a complete hollow obturator prosthesis as a single unit in heat-polymerized acrylic resin using a single-step flasking procedure.     

Hibitane in the treatment of oral candidiasis

Denture stomatitis (chronic atrophic candidosis) is a very common complication to the wearing of complete dentures. The infection is due to a contamination of the denture by yeasts. In a number of studies the clinical effect of Hibitane when used as a denture disinfectant has been studied. It was found that Hibitane (0.2--2%) caused a significant amelioration of inflamed palatal tissues and a reduction in the number of yeast cells harbored on the palatal mucosa and the fitting surface of the dentures. However, relapse of the infection was frequent after treatment was sustained. It was concluded that Hibitane could not be recommended for routine denture disinfection, first, because it caused staining of the dentures, second, because of the relative resistance of the yeast to the action of the drug. However, it seems justified to use Hibitane prophylactically as a denture disinfectant in patients who are highly susceptible to developing disseminating or systemic candidosis. Hibitane is a valuable drug in the treatment of denture stomatitis when used as a denture disinfectant.     

Helicobacter pylori and Campylobacter rectus share a common antigen

AIM: The aim of this study was to investigate the presence of antigens with immunological cross-reactivity in periodontopathogenic bacteria and Helicobacter pylori, the pathogen associated with gastritis and peptic ulcers in human. MATERIALS AND METHODS/RESULTS: Among the putative periodontopathogens tested (Actinobacillus actinomycetemcomitans, Campylobacter rectus, Fusobacterium nucleatum, Porphyromonas gingivalis, Prevotella intermedia and Treponema denticola), cross-reactive bands were only detected in C. rectus by SDS-PAGE/Western immunoblotting analysis using a polyclonal antibody directed to H. pylori cells. One of these cross-reactive antigens, a 64-kDa band antigen, also reacted with a monoclonal antibody directed to the human heat shock protein (HSP) 60. The N-terminal amino acid sequence of this C. rectus protein revealed a high degree of homology with corresponding regions of other HSPs belonging to the HSP60 family, indicating that the 64-kDa antigen was a GroEL protein. The nucleotide sequence of the C. rectus GroEL protein coded for a 547 amino acid protein with a predicted size of 57.8 kDa. Comparison of the alignment of the deduced amino acid sequence of the GroEL protein of C. rectus with that of H. pylori showed a high degree of similarity throughout its length (76.8%). GroEL protein from C. rectus possessed the ability to stimulate production of IL-6 by a confluent monolayer of human gingival epithelial cells and was cytotoxic when used at a high concentration. CONCLUSIONS: This study reveals an immunological relationship between H. pylori and C. rectus, and clearly indicates that one of the shared antigens is a GroEL protein possessing a biological activity that might play a role in the initiation and progression of periodontal disease.     

Calcium hydroxide barrier over the apical root-end of a type III dens invaginatus after endodontic and surgical treatment

AIM: To report the simultaneous endodontic and surgical treatment of a tooth associated with Oehlers type III dens invaginatus and a persistent periapical lesion, which comprised root-end resection, root-end filling and application of a calcium hydroxide barrier placed on the resected dentine surface. SUMMARY: Three root canals were identified in a tooth with a type III dens invaginatus, which presented with a necrotic pulp, wide foraminal opening and extensive periapical lesion, and with a previous history of acute abscess, intracanal exudate and fistula. After root canal preparation followed by intracanal application of calcium hydroxide pastes, the clinical-pathological status persisted. After periapical curettage and root-end resection, the root canals were filled, followed by root-end filling with Sealer 26 mixed with zinc oxide powder to a clay-like consistency. Calcium hydroxide paste was then applied over the exposed dentinal surface forming a covering over the root apex. At the 20-month follow-up examination the patient had no symptoms and no fistula; advanced periapical bone repair was obvious on the radiograph. KEY LEARNING POINTS: Because of the variable morphology and extent of invagination, type III dens invaginatus represents a challenge for conventional treatment, often leading to the need for a surgical approach. Sealer 26 thickened with zinc oxide powder provided satisfactory clinical properties for use as a root-end filling material. Application of a calcium hydroxide barrier over the resected root-end is a potential treatment option to encourage tissue repair.     

Autotransplantation of a maxillary third molar to replace a maxillary premolar with vertical root fracture

Aim To report the successful autotransplantation of a fully developed third molar that required nonsurgical and surgical interventions for tooth adaptation. Summary This case report describes the autotransplantation of a third molar with complete root development after the loss of a fractured premolar in a 47-year-old male. To allow better adaptation of the donor tooth, the buccal roots of the third molar were removed using a diamond bur and the canal entrances were filled. Recall examination 6 years after completion of root-canal treatment showed normal periodontal healing with absence of infection, ankylosis or progressive resorption. The transplantation of a third molar is seen as a promising method to replace a lost permanent tooth, and to restore aesthetics and function. Key learning points

• • Autotransplantation is a viable option for the treatment of a missing tooth or for replacement of traumatized tooth when there is a donor tooth available.
• • Fully developed third molars are potentially reliable candidates in the absence of other suitable donor teeth.

     

In vivo fractures of endodontically treated posterior teeth restored with enamel-bonded resin

Abstract The cumulative survival rate of 190 endodontically treated posterior teeth were assessed in a retrospective study; all teeth had an MO/DO or an MOD cavity restored with a composite resin without cuspal overlays after previous acid-etching of the enamel. In contrast to our previous study on endontically treated posterior teeth restored with amalgam, the survival rate of the MOD resin-restored teeth was equal to that of MO/DO teeth. Teeth restored with a light-activated resin had a much lower survival rate than teeth restored with a chemically-activated material, the cause presumably being that the light-activated resins were insufficiently irradiated. Nearly 25% of the teeth had been restored with a microfilled resin for anterior use and these teeth had a lower survival rate than had teeth restored with a macrofilled or hybrid resin. It was also found that a beveling technique did not decrease the fracture rate while the use of an intermediate layer of low-viscosity resin resulted in a significant improvement.     

Calculation of colour resulting from composite/compomer layering techniques

This study determined the influence of optical properties of constituent layers on the colour of double-layer aesthetic filling materials. Multiple regression equations for the Commission Internationale de I'Eclairage (CIE) L*, a* and b* of layered materials were calculated from the optical values of the covering and underlying layers. Specimens (10 mm diameter, 1 mm thickness) of two light-cured resin composites and one compomer of seven to 11 shades were used. CIE L*, a* and b* values of each specimen were measured with a colour spectrophotometer backed by a standard white background. The scattering coefficient (S), absorption coefficient (K), contrast ratio (C) and translucency parameter (T) were calculated. Double-layered specimens were formed in optical contact by joining two different shades from the same material, or resin composite as covering with a compomer underlying layer. Each of the L*, a* and b* of layered material was used as a dependent variable, and 14 optical values of underlying and covering layers were used as independent variables in forward regression analysis (P = 0.01). CIE L* after layering had a positive correlation with S of covering layer (correlation coefficient; beta = 0.79-0.91, P < 0.01) and a correlation with L* of underlying layer (beta = 0.14-0.16). CIE a* after layering had a correlation with a* of covering layer (beta = 0.83-0.94) and a correlation with a* of underlying layer (beta = 0.30-0.56). CIE b* after layering had a correlation with b* of covering layer (beta = 0.77-0.90) and a correlation with T of covering layer (beta = 0.40-0.59). The layered colour of these materials can be predicted by the derived regression equations within the limitations of this study. CIE L*, a* and b* values of double-layer material are mainly influenced by S, CIE a* and b* of covering layer, respectively.     

Methodological challenges in the study of dental occlusion

This narrative review describes the methodological challenges in the study of dental occlusion. The reigning confusion about the scope of this topic is discussed, and a conceptual framework for understanding dental occlusion research is suggested. The characteristics of clinical studies used in the study of dental occlusion are presented within this proposed framework consisting of a triad comprising the relative positions of the teeth-mandible-maxilla, the oral functions and oral appearance. Challenges in the preparation for a clinical study of dental occlusion are reviewed, which include a discourse on the objectives of a clinical study and appropriateness of different study designs. Guidelines are provided for the conduct of studies with a central focus on dental occlusion and diagnostic tests, prognosis, therapy and aetiology, respectively. Summarising chapters present methodological challenges in designing a clinical study of dental occlusion and threats to the proper conduct of a clinical study.     

Serial extraction: 20 years of follow-up

This paper reports a case treated by a serial extraction program at the mixed dentition stage followed by a corrective orthodontic treatment, with a long-term follow-up period. Twenty years after the interceptive treatment, a harmonious face was observed along with treatment stability in the anterior posterior direction, deep overbite (which has been mentioned as a disadvantage of the serial extraction program), and a small relapse of anterior tooth crowding. All these conditions have been regarded as normal occurrences for most orthodontic treatments with a long-term follow-up period. This case report demonstrated that the establishment of a serial extraction protocol determined relevant esthetic changes that afforded an improvement of the patient''s self-esteem, with a positive social impact. Furthermore, the low cost of this protocol permits the use of this therapy with underprivileged populations. It is important to emphasize that an early correction of tooth crowding by this protocol does not guarantee stability, but small relapses do not invalidate its accomplishment.     

Complex endodontic and conservative treatment of a traumatized central incisor

ObjectivesThe functional recovery of a tooth with open-apex already endodontically treated is possible thanks to the materials, such as the MTA, able to produce an effective seal of the apex which can induce a restitutio-ad-integrum. A direct composite resin restoration may then provide a coronal seal immediate and effective in time, able to ensure a complete healing of the endodontic pathology.Materials and methodsThe hereby-clinical case describes a combined approach (endodontic and conservative) for the aesthetic-functional recovery of a severely fractured upper incisor of a child of 11 years.Results and conclusionsAt the control visit, after 12 months from the completion of the coronal restoration, a complete healing of periradicular bone tissue is observed through Rx. Clinical examination showed gingival tissue without inflammation and the probing depth is not increased, despite the presence of a cavity margin placed below the gingival margin.     

Influence of differences in the hardness and calcium content of diets on the growth of craniofacial bone in rats

Objective:To examine the effects of a soft diet and a low-calcium diet on the craniofacial growth and bone architectures of the maxilla and mandible.Materials and Methods:Male rats (n  =  20, 3 weeks old) were divided into four groups. Ten rats were given a normal-calcium diet, and the other rats were given a low-calcium diet. Each group was then divided into two subgroups, which were fed a hard or a soft diet. After 4 weeks, craniofacial growth and architecture in maxillary and mandibular bone were analyzed using cephalometry, micro-computed tomography, and histopathology.Results:The low-calcium diet had no effect on serum calcium levels. The low-calcium diet had the greatest effect on craniofacial bone growth, while the soft diet affected the growth of several bone sites that are attached to the masseter muscle. A low-calcium diet resulted in the deterioration of the connectivity of the trabeculae in the furcation region of the maxillary and mandibular first molar, while a soft diet resulted in the diffuse disappearance of trabeculae in the central part of the furcation regions. In the midpalatal suture, a low-calcium diet resulted in inhibition of cartilaginous ossification, although the midpalatal suture had a normal cartilaginous structure. A soft diet resulted in narrower cartilage cell layers in the midpalatal suture.Conclusions:We demonstrated that a low-calcium diet and a soft diet resulted in a deterioration of bone structures in both the maxilla and in the mandible; however, the mechanisms underlying these effects differed between diets.