Longitudinal study on the influence of Nd:YAG laser irradiation on microleakage associated of two filling techniques.

Objective: This study investigates the effects of Nd:YAG laser irradiation on apical and coronal seals, when used prior to two root canal filling techniques. Background Data: Limited information exists regarding the effects of morphologic changes to dentin walls following Nd: YAG laser irradiation on the sealing ability of root fillings. Methods: Two hundred forty teeth were analyzed by observing coronal and apical leakage of Indian ink (DL), and 60 were analyzed for through-and-through leakage using the fluid transport model (FTM). The Nd: YAG laser parameters were 1.5W, 100mJ, and 15Hz (four times for 5s at 20s intervals). Each group consisted of a lased and a nonlased subgroup: each subgroup had root fills done by either cold lateral condensation (CLC) or hybrid condensation (HC). Leakage was assessed after 48 h, and then at 1, 6, and 12 months. The DL group was divided into four groups of 15 teeth for each evaluation point. Through-and-through leakage (L in microliters/day) was measured for 48h under a pressure of 1.2 atm using FTM, and recorded as L = 0 (L1), 0 10 (L3). Results: Apical and coronal dye leakage was observed in all groups. Significant differences (p < 0.05) in apical leakage were found between HC and HC + Nd after 1, 6, and 12 months, and between CLC and CLC + Nd at 6 and 12 months. No significant differences were found between laser-irradiated and non-laser-irradiated groups with FTM. Conclusion: Pulsed Nd: YAG laser irradiation following root canal preparation may reduce apical leakage in association with hybrid gutta-percha condensation

Investigation of coronal leakage of root fillings after smear layer removal with EDTA or Nd:YAG lasing through capillary flow porometry

Objective: This study investigates the effects of Nd:YAG laser irradiation combined with different irrigation protocols on the marginal seal of root fillings. Background data: Limited information exists regarding the effects of morphologic changes to root canal (RC) walls after Nd:YAG laser irradiation after smear-layer removal with EDTA on the sealing ability of root fillings. Methods: The 75 root-filled teeth (5 × 15 teeth) were analyzed for through-and-through leakage by using capillary flow porometry (CFP). The RC cleaning procedure determined the assignment to a group: (1) irrigation with NaOCl 2.5% and EDTA 17% or standard protocol (SP), (2) SP + Nd:YAG lasing (dried RC), (3) NaOCl 2.5% + Nd:YAG lasing (dried RC), (4) SP + Nd:YAG lasing (wet RC), or (5) NaOCl 2.5% + Nd:YAG lasing (wet RC). Groups 1r to 5r consisted of the same filled teeth with resected apices up to the most apical point of the preparation length. Resection was performed after the first CFP measurement. Roots were filled with cold lateral condensation. CFP was used to assess minimum, mean flow and maximum pore diameters after 48 h, and immediately after these measurements, including root resection. Statistics were performed by using nonparametric tests (p > 0.05). An additional three roots per group were submitted to SEM of the RC wall. Results: Through-and-through leakage was observed in all groups. Statistically significant differences were observed in maximum pore diameter: 1r > 3r, and 1r > 5r; in mean flow pore diameter: 1r > 2r, 2r < 4r (p < 0.05). Typical Nd:YAG glazing effects were observed when the smear layer was present and exposed to the laser fiber (i.e., in the groups without use of EDTA) or when the fiber tip made direct contact with a smear-layer free RC wall. Conclusions: The reduction in through-and-through leakage is significantly higher with the Nd:YAG laser as smear-layer modifier than when smear layer is removed with an EDTA rinsing solution

External cervical resorption: an analysis using cone beam and microfocus computed tomography and scanning electron microscopy

AIM: To provide a three-dimensional representation of external cervical resorption (ECR) with microscopy, stereo microscopy, cone beam computed tomography (CT), microfocus CT and scanning electron microscopy (SEM). SUMMARY: External cervical resorption is an aggressive form of root resorption, leading to a loss of dental hard tissues. This is due to clastic action, activated by a damage of the covering cementum and stimulated probably by infection. Clinically, it is a challenging situation as it is characterized by a late symptomatology. This is due to the pericanalar protection from a resorption-resistant sheet, composed of pre-dentine and surrounding dentine. The clastic activity is often associated with an attempt to repair, seen by the formation of osteoid tissue. KEY LEARNING POINTS: Cone beam CT is extremely useful in the diagnoses and treatment planning of ECR. SEM analyses provide a better insight into the activity of osteoclasts. The root canal is surrounded by a layer of dentine that is resistant to resorption.status: publishe

Swimming Pool Regulations in the COVID-19 Era: Assessing Acceptability and Compliance in Greek Hotels in Two Consecutive Summer Touristic Periods

The COVID-19 pandemic has urged many countries to issue new regulations to assure safety in pool environments. Greece enforced stricter requirements in 2020 and 2021 for hotel pools. However, even though regulations are important, they can only be effective when accepted by the pool managers and users. The aim of this study was to (a) assess the acceptability of the regulations by hotel managers; (b) assess compliance during the summer touristic periods in 2020 and 2021; and (c) identify challenges during the implementation of the regulations that need to be addressed. Several non-compliances from the regulations were identified. Continuous chlorination with an automatic chlorinator was not a regular practice and suggested water circulation rates were poorly met. The microbiological and chemical testing frequency of the pool water and keeping the number of bathers allowed per surface area in the pool were reported as the most difficult requirements to meet. Most pool managers agreed that new measures contribute to the pool users’ safety; however, they reported increased cost as the main impediment for their implementation. The modernization of regulations governing swimming pools’ function, in terms of risk assessment orientation, will contribute to the adoption of an integrated compliance strategy on emerging health issues, such as COVID-19

A novel multimodular methodology to investigate external cervical tooth resorption

Aim To introduce a multimodular combination of techniques as a novel minimal invasive approach to investigate efficiently and accurately external cervical resorption (ECR). Methodology One case of a central incisor with extensive external cervical resorption was selected to demonstrate the potential of a comparative novel study methodology. ECR diagnosis was based on clinical inspection, digital radiography and cone-beam computed tomography (CBCT). After extraction, the tooth was investigated using microfocus computed tomography (micro-CT), nano-CT and hard tissue histology. These techniques were compared for their accuracy and applicability to highlight their advantages and disadvantages. Results Nano-CT was more effective than micro-CT and CBCT for detailed ex vivo exploration of ECR. The reparative tissue, pericanalar resorption resistant sheet (PRRS), pulp tissue reactions, resorption channels and their interconnection with the periodontal ligament space were accurately visualized by detailed processing and analysis of the nano-CT data set with Dataviewer and CTAn software. Nano-CT analysis provided better insight in the true extent of the resorption, based on quantitative measurements and 3D visualization of the tooth structure. Nano-CT imaging results were similar to hard tissue histology at the mineralized tissue level. To clarify the dynamic phenomenon of reparative tissue formation and substitution of the resorbed tissues, nano-CT needed to be associated with hard tissue histology. Conclusion Nano-CT is a fast and minimal invasive technique for the ex vivo analysis and understanding of ECR and is complementary with hard tissue histology. A combined approach of clinical and CBCT examination, with nano-CT and histological mapping measurements, can provide an ideal platform for future ECR imaging and exploration studies.status: publishe

Regenerative endodontic procedure of an infected immature permanent human tooth: an immunohistological study

OBJECTIVES: An immunohistological study of an infected immature permanent human tooth after a regenerative endodontic procedure (REP) was conducted in order to determine the histologic outcome of this procedure. Besides observed signs of angiogenesis and neurogenesis, repair and/or regeneration of the pulp-dentin complex was also investigated. MATERIALS AND METHODS: A REP was performed on tooth 45 of a 10-year-old girl. Eleven months post-treatment, the tooth had to be removed for orthodontic reasons. The following investigations were performed: immunohistology and radiographic quantification of root development. After hematoxylin-eosin (HE) staining, the following immunomarkers were selected: neurofilament (NF), pan cytokeratin (PK), osteocalcin (OC), and CD34. RESULTS: The REP resulted in clinical and radiographic healing of the periradicular lesion and quantifiable root development. The HE staining matches with the medical imaging post-REP: underneath the mineral trioxide aggregate a calcified bridge with cell inclusions, connective pulp-like tissue (PLT) with blood vessels, osteodentin against the root canal walls, on the root surface cementum (Ce), and periodontal ligament (PDL). The PDL was PK(+). The blood vessels in the PLT and PDL were CD34(+). The Ce, osteodentin, and stromal cells in the PLT were OC(+). The neurovascular bundles in the PLT were NF(+). CONCLUSIONS: Immunohistologically, REP of this infected immature permanent tooth resulted in an intracanalar connective tissue with a regulated physiology, but not pulp tissue. CLINICAL RELEVANCE: REP of an immature permanent infected tooth may heal the periapical infection and may result in a combination of regeneration and repair of the pulp-dentin complex.status: publishe

Regenerative Endodontic Procedures Posttrauma: Immunohistologic Analysis of a Retrospective Series of Failed Cases

INTRODUCTION: Regenerative endodontic procedures (REP) are a novel treatment modality to restore the function of necrotic pulp tissue via stimulation or transplantation of stem cells into the root canal. This study aimed to investigate the immunohistologic outcome of 3 extracted teeth because of sequelae of trauma and unsatisfactory REP outcomes. METHODS: Three immature permanent maxillary central incisors of 3 female patients (6-9 years) were extracted 5.5-22 months after REP. Additionally, 1 sound permanent immature central maxillary incisor of 1 of the included patients was extracted for orthodontic reasons. The teeth were immunohistologically stained with Masson's trichrome, neurofilament (NF), pan cytokeratin, dentin sialophosphoprotein, and Gram+/-. RESULTS: The REP-teeth presented intracanalar vascularized connective/mineralized reparative tissue (RT), which was less organized than the pulp tissue of the sound tooth. Moderate to considerable calcification was observed below the Portland cement used during REP. In 1 case, the RT was NF+; in the 2 other cases, the periodontal ligament and apical granuloma/papilla were NF+. All teeth were Gram+/- negative; nevertheless, inflammatory cells were present in 2 cases. The pan cytokeratin and dentin sialophosphoprotein stainings were not specific enough for 2 cases. CONCLUSIONS: This immunohistologic study of failed REP cases resulted in bacteria-free intracanalar RT and biomaterial-induced calcification. Nevertheless, the presence of inflammatory cells revealed a persistent inflammation. Hence, the clinical and radiographic signs were decisive for tooth survival and multidisciplinary outcome determination.status: publishe

Applications of CT for non-destructive testing and materials characterization

Several important technological and economic trends are shaping the research on non-destructive testing techniques. X-ray computed tomography is also a NDT product of these ongoing developments and has become a very important tool for doctors, material scientists, geologists, biologists, civil engineers, bio-engineers, dentists, quality engineers, etc., all dealing with materials of which the fine internal structure or the changes within the material are of outmost importance to understand the behaviour of the material or to have insights in the processes going on. X-ray CT with micron- and submicron resolution is now well accepted in those disciplines. In the next paragraphs a wide variety of application fields will be addressed in order to show how X-ray CT can be applied as an NDT technique for quality control, the study of the material behaviour and its functional properties under specified environmental conditions, and for production and material optimization

Application of multivariate statistical methods for groundwater physicochemical and biological quality assessment in the context of public health

Three representative areas (lowland, semi-mountainous, and coastal) have been selected for the collection of drinking water samples, and a total number of 28 physical, chemical, and biological parameters per water sample have been determined and analyzed. The mean values of the physical and chemical parameters were found to be within the limits mentioned in the 98/83/EEC directive. The analysis of biological parameters shows that many of the water samples are inadequate for human consumption because of the presence of bacteria. Cluster analysis (CA) first was used to classify sample sites with similar properties and results in three groups of sites; discriminant analysis (DA) was used to construct the best discriminant functions to confirm the clusters determined by CA and evaluate the spatial variations in water quality. The standard mode discriminant functions, using 17 parameters, yielded classification matrix correctly assigning 96.97% of the cases. In the stepwise mode, the DA produced a classification matrix with 96.36% correct assignments using only ten parameters (EC, Cl (-aEuro parts per thousand), NO(3) (-aEuro parts per thousand), HCO(3) (-aEuro parts per thousand), CO(3) (-aEuro parts per thousand 2), Ca (+ 2), Na (+) , Zn, Mn, and Pb). CA and factor analysis (FA) are used to characterize water quality and assist in water quality monitoring planning. CA proved that two major groups of similarity (six subclusters) between 17 physicochemical parameters are formed, and FA extracts six factors that account for 66.478% of the total water quality variation, when all samples' physicochemical data set is considered. It is noteworthy that the classification scheme obtained by CA is completely confirmed by principal component analysis