Contrast-enhanced nano-CT reveals soft dental tissues and cellular layers.

AIM: To introduce a methodology designed to simultaneously visualize dental ultrastructures, including cellular and soft tissue components, by utilizing phosphotungstic acid (PTA) as a contrast-enhancement agent. METHODOLOGY: Sound third molars were collected from healthy human adults and fixed in 4% buffered paraformaldehyde. To evaluate the impact of PTA in concentrations of 0.3%, 0.7% and 1% on dental soft and hard tissues for CT imaging, cementum and dentine-pulp sections were cut, dehydrated and stained with immersion periods of 12, 24 h, 2 days or 5 days. The samples were scanned in a high-resolution nano-CT device using pixel sizes down to 0.5 µm to examine both the cementum and pulpal regions. RESULTS: Dental cementum and periodontium as well as odontoblasts and predentine were made visible through PTA staining in high-resolution three-dimensional nano-CT scans. Different segments of the tooth required different staining protocols. The thickness of the cementum could be computed over the length of the tooth once it was made visible by the PTA-enhanced contrast, and the attached soft tissue components of the interior of the tooth could be shown on the dentine-pulp interface in greater detail. Three-dimensional illustrations allowed a histology-like visualization of the sections in all orientations with a single scan and easy sample preparation. The segmentation of the sigmoidal dentinal tubules and the surrounding dentine allowed a three-dimensional investigation and quantitative of the dentine composition, such as the tubular lumen or the ratio of the tubular lumen area to the dentinal surface. CONCLUSION: The staining protocol made it possible to visualize hard tissues along with cellular layers and soft tissues in teeth using a laboratory-based nano-CT technique. The protocol depended on both tissue type and size. This methodology offers enhanced possibilities for the concomitant visualization of soft and hard dental tissues.

PRICE 2020 guidelines for reporting case reports in Endodontics: a consensus-based development.

Case reports can provide early information about new, unusual or rare disease(s), newer treatment strategies, improved therapeutic benefits and adverse effects of interventions or medications. This paper describes the process that led to the development of the Preferred Reporting Items for Case reports in Endodontics (PRICE) 2020 guidelines through a consensus-based methodology. A steering committee was formed with eight members (PD, VN, BC, PM, PS, EP, JJ and SP), including the project leaders (PD, VN). The steering committee developed an initial checklist by combining and modifying the items from the Case Report (CARE) guidelines and Clinical and Laboratory Images in Publications (CLIP) principles. A PRICE Delphi Group (PDG) and PRICE Face-to-Face Meeting Group (PFMG) were then formed. The members of the PDG were invited to participate in an online Delphi process to achieve consensus on the wording and utility of the checklist items and the accompanying flow chart that was created to complement the PRICE 2020 guidelines. The revised PRICE checklist and flow chart developed by the online Delphi process was discussed by the PFMG at a meeting held during the 19th European Society of Endodontology (ESE) Biennial Congress in Vienna, Austria, in September 2019. Following the meeting, the steering committee created a final version of the guidelines, which were piloted by several authors during the writing of a case report. In order to help improve the clarity, completeness and quality of case reports in Endodontics, we encourage authors to use the PRICE 2020 guidelines.

Validation of contralateral premolars as the substrate for endodontic comparison studies.

AIM: To use micro-CT technology and metrology software to validate the use of contralateral premolars as samples in endodontic comparison studies by comparing them before and after canal instrumentation with one instrumentation system. Furthermore, to determine whether contralateral premolar roots (CPRs) will yield non-significantly different outcomes regarding shaping ability (volume), degree of twisting and three-dimensional shape changes. The null-hypothesis (H0 ) is that there are no differences between the CPRs pre- or post-instrumentation. METHODOLOGY: Twenty-eight extracted human contralateral premolars (n = 44 contralateral roots) from 12 donor patients were scanned with microcomputed tomography before and after instrumentation. Root canal lengths (RCLs) were measured visually using a dental-operating microscope, electronic apex locator and micro-CT scans. Data were analysed statistically for differences between pre- and post-instrumentation. RESULTS: Instrumentation increased the volume of the canals significantly (P < 0.05). Degree of twisting for a majority (83%) of the contralateral roots pairs did not change significantly (P > 0.05). There was no significant difference (P > 0.05) in the shape deviation analysis between contralateral pairs. There was no significant difference (P > 0.05) for RCL between the contralateral pairs for any of the three endometric methods. CONCLUSION: Contralateral premolar root canals were associated with similar changes in terms of volume, three-dimensional shape and degree of twisting from pre- to post-instrumentation. There was no difference between the CPR pairs pre- and post-instrumentation, and the study validates contralateral premolars as samples for root canal comparison studies. The null-hypothesis (H0 ) could not be rejected.

Human papillomavirus subtypes in oral lesions compared to healthy oral mucosa.

BACKGROUND: Human papillomaviruses (HPV) are involved in the etiology of cervix cancer, but it is still unclear whether they play a role in related oral lesions. OBJECTIVES: The presence of HPV in oral leukoplakia biopsies (n=50) and oral squamous carcinoma biopsies (n=50) was compared to normal oral mucosa swabs (n=50) for the purpose of indicating a possible etiological role for the virus. STUDY DESIGN: DNA was extracted from tissue biopsies and from mucosa swabs of control samples. Nested PCR was performed with primers targeting conserved sequences within the capsid gene L1. PCR products were sequenced to identify the HPV genotype. RESULT: The results reveal a profile of low-risk HPV genotypes in oral leukoplakia similar to that in healthy controls, while HPV was less frequently observed in oral squamous carcinoma. CONCLUSIONS: HPV does not seem to represent an important causal factor for the development of oral leukoplakia or oral squamous carcinoma.

Extraradicular infection: a methodological study.

Whether bacteria live or die in periapical lesions of endodontic origin is debated. Sampling of periapical bacteria is difficult due to possible contamination from the indigenous microflora. The aim of this study was to examine whether bacteria were present in periapical lesions of asymptomatic teeth before sampling or were transferred there during sampling. Thirty patients with root-filled teeth and periapical radiolucencies were divided into two groups, each containing 15 patients. In Group 1, a marginal incision was made to explore the periapical lesion. In Group 2, a submarginal incision was made. Before incision, the gingiva and mucosa were washed with 0.2% chlorhexidine gluconate. Bacterial samples were taken from the mucosa before reflecting the flap, and from the alveolar bone and the periapical lesion immediately after. All samples were cultured anaerobically on all-purpose and selective media. In Group 1, 12 of the 15 patients (80%) yielded bacteria from their mucosal samples despite the chlorhexidine wash. Bacterial growth was observed in all samples (100%) from the alveolar bone while the periapical lesions gave bacterial growth in 11 of 15 cases (73%). In Group 2, bacteria were cultured from the mucosa in 11 of 15 (73%) patients. Three samples (20%) from the alveolar bone and 10 from the periapical lesions (67%) gave positive growth. The predominant cultivable bacteria were anaerobic. Phenotypic profiling, performed with the data-based API bioMérieux system, indicated that the sampling technique used prevented mucosal bacteria from reaching the exposed bone and the periapical lesions. Profiling also indicated that following marginal incision, bacteria from the periodontal pocket might have reached the underlying tissues by surgeon-released bacteremia or direct translocation. Most organisms detected in the periapical lesions were clearly different from the bacteria present at neighboring sites and appeared to have been there before sampling.

Assessment of periradicular microbiota by DNA-DNA hybridization.

In the present study the "checkerboard" DNA-DNA hybridization technique was used to identify bacteria in periapical endodontic lesions of asymptomatic teeth. Thirty-four patients with root-filled teeth and apical periodontitis were divided into two groups, each containing 17 patients. In Group 1, a marginal incision was performed during surgery to expose the lesion, and in Group 2, a submarginal incision was applied. The gingiva and mucosa were swabbed with an 0.2% chlorhexidine gluconate solution prior to surgery. Bacterial DNA was identified in all samples from the two groups using 40 different whole genomic probes. The mean number (+/- SD) of species detected was 33.7 +/- 3.3 in Group 1 and 21.3 +/- 6.3 in Group 2 (P < 0.001). The majority of the probe-detected bacteria were present in more lesions from Group 1 than from Group 2. The differences were most notable for Campylobacter gracilis, Porphyromonas endodontalis, Propionibacterium acnes, Capnocytophaga gingivalis, Fusobacterium nucleatum ssp. nucleatum, Fusobacterium nucleatum ssp. polymorphum, Prevotella intermedia, Treponema denticola, Streptococcus constellatus and Actinomyces naeslundii I. Bacterial species such as Actinobacillus actinomycetemcomitans and Bacteroides forsythus were detected in more than 60% of the lesions from both groups. Also, P. endodontalis was abundant in periapical tissue. The data supported the idea that following a marginal incision, bacteria from the periodontal pocket might reach the underlying tissues by surgeon-released bacteremia. The study provided solid evidence that bacteria invade the periapical tissue of asymptomatic teeth with apical periodontitis. The detection of much more bacteria with the "checkerboard" DNA-DNA hybridization method than has previously been recovered by anaerobic culture indicated that the endodontic (and periodontal) microfloras should be redefined using molecular methods.