Transaminases in the acquired pellicle

Objective

Transaminases (AST, aspartate amino transferase; ALT, alanine amino transferase) are relevant enzymes in physiology and pathology of the human organism. The aim of the present in situ study was to demonstrate the presence of these enzymes in the enamel pellicle.

Methods

Bovine enamel slabs were fixed on buccal sites of individual upper jaw splints and worn for 3, 30 and 120 min by 5 subjects to allow pellicle formation. The in situ pellicles were tested for AST and ALT. Enzyme activities were measured photometrically via determination of the products pyruvate and oxalacetate using lactate-dehydrogenase and malate-dehydrogenase, respectively.

Results

Enzymatic AST- as well as ALT-activities are present in the acquired pellicle within 3 min. The enzyme activities exposed at the pellicles’ surfaces increased slightly with the pellicle formation time (ANOVA, AST: n.s., ALT: p = 0.021). However, the two enzymes show considerable intraindividual and interindividual variability. The mean AST-activity of the pellicle amounted to 1.07 ± 0.81 mU/cm² (ALT 1.18 ± 0.52 mU/cm²). The ALT-activity of the centrifuged saliva was 26.62 ± 11.09 mU/ml (AST 35.98 ± 29.35 mU/ml).

Conclusions

AST as well as ALT are present in the in situ pellicle layer and may contribute to the intrinsic maturation of pellicle proteins.     

In vitro synchronization of embryonic mouse incisor preodontoblasts and preameloblasts: repercussions on terminal differentiation

Preodontoblasts divide asynchronously and their terminal differentiation occurs gradually. Experimental data suggested that the expression of competence by preodontoblasts to respond to specific epigenetic signals, triggering their overt differentiation, requires a minimal number of cell cycles. The intrinsic timing mechanism could imply division counting and preodontoblasts of juxtaposed cell generations might sequentially withdraw from the last physiological cycle. To test such an hypothesis, embryonic mouse lower incisors were cultured in vitro and treated sequentially with nocodazole in order to induce a transitory synchronization of the dividing preodontoblasts and preameloblasts. This synchronization led to a disorganization of the physiological gradual terminal differentiation of the odontoblasts, giving rise to three distinct domains comprising respectively: 1) odontoblasts with altered polarization and predentin secretion; 2) odontoblasts demonstrating equivalent polarization and predentin deposition; and 3) preodontoblasts-odontoblasts involved in gradual terminal differentiation. These results strongly suggest that the gradient of odontoblast functional differentiation results from sequential withdrawal from asynchronous cell cycles of competent cells able to overtly differentiate.     

A practice-based evaluation of the handling of a new self-adhesive universal resin luting material

OBJECTIVE: Ease of handling of materials may be considered helpful to achieving good results. The handling properties of a new self-adhesive universal resin luting material were tested in clinical use. METHOD AND MATERIAL: Thirteen practitioners were selected at random from the Product Research and Evaluation by Practitioners (PREP) Panel, a United Kingdom-based group of dental practitioners prepared to complete evaluations of new materials and techniques in the practice environment. Explanatory letters, questionnaires and packs of the luting material were sent to the evaluators. The practitioners were asked to use the material and return the questionnaire. RESULTS: 144 restorations were placed using the new self-adhesive resin luting material, which was rated higher by the evaluators for ease of use (4.7 on a visual analogue scale where 5 represented easy to use and 1 represented difficult to use) than both the pre-trial resin-based and 'conventional' luting materials (rated 3.7 and 4.4 respectively on the same scale). The presentation, instructions, convenience of dispensing and handling and viscosity also received high ratings. CONCLUSION: The new material achieved ratings for ease of use superior to the pre-study resin-based and conventional luting materials in the dental practices of 13 UK dental practitioners.     

Molecular evaluation of residual endodontic microorganisms after instrumentation, irrigation and medication with either calcium hydroxide or Septomixine

BACKGROUND AND OBJECTIVE: The correct choice of antimicrobial agents as inter-appointment medicaments is as important as the instrumentation and irrigation to remove pathogens from infected root canals. Calcium hydroxide [Ca(OH)2] and framycetin sulfate (Septomixine) are common endodontic medicaments. Therefore, we evaluated the efficacy of either calcium hydroxide or Septomixine in eliminating residual intra-canal bacteria, particularly Actinomyces spp., during inter-appointment interval in endodontic therapy using molecular methods. METHODS: A total of 31 single-rooted teeth with primary root canal infections were studied immediately after opening the canals and subsequently after instrumentation, irrigation with sterile saline and 1-week medication with either Ca(OH)2 (n = 25) or Septomixine (n = 6). Whole bacterial genomic DNA was isolated directly from samples and PCR with universal primers performed to detect total intra-canal bacteria. The variable regions of 16S rDNA of bacteria were amplified and labeled with digoxigenin for further hybridization to detect Actinomyces spp. A total of seven oligonucleotide probes specific for A. bovis, A. gerencseriae, A. israelii, A. meyeri, catalase-negative A. naeslundii (genospecies 1 and 2), catalase-positive A. naeslundii genospecies 2 and A. odontolyticus were used to detect Actinomyces spp. in 22 of 31 medicated root canals [Ca(OH)2: n = 17; Septomixine: n = 5]. RESULTS: The PCR results showed that 25 of 31 examined canals were positively detected with residual microorganisms after instrumentation, irrigation with sterile saline and 1-week medication with either Ca(OH)2 (n = 20) or Septomixine (n = 5). Thus, only six canals [Ca(OH)2: n = 5, Septomixine: n = 1] were aseptic after treatment. Hybridization results showed higher detection frequency of both A. odontolyticus and A. gerencseriae after treatment. Significant correlation was found between exposed pulp before treatment and positive detection of Actinomyces spp., particularly A. odontolyticus on the second visit (P < 0.05). CONCLUSION: The conventional, 1-week medication of either Ca(OH)2 or Septomixine in endodontic therapy may not effectively inhibit residual bacterial growth in all root canals during inter-appointment intervals. Further investigations using, for instance quantitative real-time PCR analyses, are required to substantiate the present findings.     

Dens invaginatus type III: report of a case and 10-year radiographic follow-up

AIM: The purpose of this article is to report the 10-year follow-up of a right mandibular central incisor with 'dens invaginatus' that was root filled. SUMMARY: 'Dens invaginatus' is a rare malformation of teeth, probably resulting from an infolding of the dental papilla during tooth development. It has alternatively been called 'dens in dente' and 'dilated composite odontome'. Radiographic examination may clearly demonstrate this feature, although no signs may be recognized clinically. If no entrance to the invagination can be detected and there are no signs of pulp pathosis, then no treatment is required other than fissure sealing of the invagination. In deep invaginations, it is likely that root-canal treatment may be required. Occasionally, when the tooth has an immature root, apexification is necessary. Root-canal treatment of a right mandibular central incisor with 'dens invaginatus' is described along with 10-year follow-up. KEY LEARNING POINTS: Both clinical and radiographic examinations are necessary to determine morphological features of teeth before root-canal treatment. Sensibility testing to determine the pulp condition is critical prior to treatment.     

Campylobacter rectus in human periodontitis

Campylobacter rectus (formerly Wolinella recta ) in periodontitis lesions was studied relative to age and sex distribution, relationship to disease-active periodontitis, response to periodontal debridement and in vitro antimicrobial susceptibility. Subgingival C. rectus was collected with paper points, transported in VMGA III and plated onto nonselective enriched brucella blood agar and Hammond's selective medium for C. rectus , both incubated anaerobically. C. rectus was recovered from 80% of 1654 periodontitis patients. Although the organism showed similar age and sex occurrence, its proportional recovery in culture-positive adults was inversely related to increasing age ( r = 0.999, P <0.001). The organism was positively associated (summary odds ratio = 2.95) with disease activity in a 24-month longitudinal study of 93 adult periodontitis patients on maintenance therapy. C. rectus decreased from 8.2% to 0.7% following local periodontal debridement of 20 culture-positive adult periodontitis patients. The organism exhibited high in vitro susceptibility to therapeutic levels of tetracycline hydrochloride, metronidazole, penicillin G and ciprofloxacin. These findings further delineate the epidemiology and potential pathogenic role of C. rectus in human periodontitis.     

Dens invaginatus in a mandibular lateral incisor

A rare case of dens invaginatus involving a non-carious mandibular lateral incisor with periapical periodontitis is reported. Invaginated teeth present technical difficulties in their clinical management because of their abnormal anatomy. In the present case, non-surgical root canal therapy was chosen. A one-year follow-up clinical and radiographic examination showed a non-symptomatic tooth with osseous healing proceeding.     

同源盒基因HOXC 13在成釉细胞瘤中的表达

目的研究HOXC13 mRNA在成釉细胞瘤（ameloblastoma，AB）中的表达，探讨其发生的意义。方法采用原位杂交法检测47例AB（原发AB 29例，复发AB 14例，恶变AB 4例），同时选取骨纤维异样增殖症2例，牙源性角化囊性瘤（keratocystic odontogenic tumor，KCOT）10例，正常口腔黏膜上皮7例作对照。结果HOXC13 mRNA AB中阳性率为97．9％（46／47），10例KCOT中7例为HOXC13 mRNA阳性表达，但在7例正常口腔黏膜细胞中仅3例为HOXC13 mRNA阳性表达，AB、KCOT、正常黏膜三组间差异有统计学意义（χ^2=21．665，P=0．001），但角化及颗粒样变退化细胞却为阴性。在部分AB间质成纤维细胞质中也有阳性表达，2例骨纤维异常增殖症纤维也为阳性。结论在AB中存在HOXC13的高表达；HOXC13 mRNA在AB上皮中的表达有异质性，该基因可促进上皮的增殖，其丢失可导致上皮细胞的角化和退变。     

Diced cartilage for dorsal augmentation in rhinoplasty: effect on nasal projection and frontal nasal width

This research study was designed to evaluate the aesthetic consequences of different dorsal augmentation techniques using diced cartilage on dorsal width and projection in rhinoplasty. Patients were assigned to three groups based on the dorsal augmentation technique used: diced cartilage wrapped in fascia (DCIF), free diced cartilage under fascia (DCUF), and free diced cartilage without fascia (FDC). Dorsal projection and dorsal aesthetic width were measured at two levels using pre- and postoperative photographs. A total of 98 patients were included in the study. DCIF was used in 51 patients, FDC in 27 patients, and DCUF in 20 patients. There was no significant difference in nasion projection, rhinion projection, or width of the dorsal aesthetic lines at the intercanthal and keystone levels among these groups. Significantly greater nasion and rhinion projection was observed with DCIF in thin-skinned patients followed-up for 6–12 months (nasion, P = 0.028; rhinion P = 0.039) but not at>12 months. Two patients with a graft infection and one with graft malposition were encountered in the DCIF group. Experience from this study suggests that the application of FDC prevents such complications without sacrificing the dorsal augmentation and that DCIF is a better choice for more severe deformities.