Does the type of endodontic access influence in the cyclic fatigue resistance of reciprocating instruments?

Clinical Oral Investigations - The aim of the present study was to compare the cyclic fatigue resistance of Reciproc R25 (R25) and Reciproc Blue R25 (R25B) instruments, after simulated clinical use...     

Does the presence of maxillary midline diastema influence the perception of dentofacial esthetics in video analysis?

ObjectiveTo evaluate the influence of a midline diastema on dentofacial esthetic perceptions of orthodontists, restorative dental specialists or prosthodontists, and laypersons in a frontal facial evaluation performed by means of video.Materials and MethodsTwo individuals aged between 20 and 25 years, one of each gender, with presence of a midline diastema were selected. An acrylic resin mockup was made of the maxillary anterior region, simulating ideal conditions of smile esthetics. Four standardized frontal view videos of the complete face were filmed of each individual in the following situations: with the ideal smile (unchanged mockup) and with the presence of midline diastemas of 0.5, 1.0, and 1.5 mm created by the mockup. In all videos, the patient said a certain sentence and, at the end, simulated a posed smile. Dentofacial esthetic perceptions of all four videos of each individual were evaluated by 51 orthodontists, 51 restorative dental specialists or prosthodontists, and 51 laypersons by means of visual analog scales. Data were evaluated using analysis of variance and Tukey post hoc test, with the level of significance set at 5%.ResultsThe most attractive videos for all groups of examiners were those without diastema and with a diastema of 0.5 mm, for both the woman and the man. For a diastema of 1 mm or 1.5 mm, the dentofacial characteristics were considered unesthetic.ConclusionsDiastemas equal to or greater than 1 mm negatively influence dentofacial esthetics in a frontal facial evaluation performed by means of video.     

Is hard tissue formation in the dental pulp after the death of the primary odontoblasts a regenerative or a reparative process?

Objectives

Conceptually, two types of tertiary dentine may be produced in response to caries and environmental irritations: “reactionary dentine” that is secreted by existing primary odontoblasts and “reparative dentine”, formed after the death of the odontoblasts by proliferation and differentiation of progenitor cells into odontoblast-like cells. Because histologic evidence for tubular dentine generated by newly differentiated odontoblast-like cells is lacking in human teeth, the present study examined pulpal cellular changes associated with caries/restorations, in the presence or absence of pulpal exposures.

Methods

Ninety-six extracted human teeth were histologically processed and serial sectioned for light microscopy: 65 contained untreated enamel/dentine caries; 20 were heavily restored and 11 had carious exposures managed by direct pulp-capping.

Results

Sparsely distributed, irregularly arranged dentinal tubules were identified from the tertiary dentine formed in teeth with unexposed medium/deep caries and in restored teeth; those tubules were continuous with the tubules of secondary dentine; in some cases, tubules were absent. The palisade odontoblast layer was reduced to a single layer of flattened cells. In direct pulp-capping of pulp exposures, the defects were repaired by the deposition of an amorphous dystrophic calcified tissue that resembled pulp stones more than dentine, sometimes entrapping pulpal remnants. This atubular hard tissue was lined by fibroblasts and collagen fibrils.

Conclusions

Histological evidence from the present study indicates that reparative dentinogenesis cannot be considered as a regenerative process since the so-formed hard tissue lacks tubular features characteristic of genuine dentine. Rather, this process represents a repair response that produces calcified scar tissues by pulpal fibroblasts.

Clinical significance

Formation of hard tissue in the dental pulp after the death of the primary odontoblasts has often been regarded by clinicians as regeneration of dentine. If the objective of the clinical procedures involved is to induce healing, reduce dentine hypersensitivity, or minimise future bacteria exposure, such procedures may be regarded as clinical success. However, current clinical treatment procedures are not adept at regenerating physiological dentne because the tissues formed in the dental pulp are more likely the result of repair responses via the formation of calcified scar tissues.     

Does the presence of maxillary central incisor edge asymmetry influence the perception of dentofacial esthetics in video analysis?

Objective:To investigate the influence of incisal edge asymmetry of the maxillary central incisors on dentofacial esthetics among orthodontists, prosthodontists, and laypersons using video analysis.Materials and Methods:Full-face films of a 52-year-old afro-descendant woman displaying various levels of incisal wear in the esthetic zone were captured. An acrylic resin mockup was made of the maxillary anterior region, enabling the reproduction of an attractive smile and restoring tooth wear. Four different levels of incisal asymmetry between the upper central incisors in 0.5 mm increments were prepared from this mockup. A film was made for each level of asymmetry (0.5, 1.0, 1.5, and 2.0) and one with no asymmetry, with the patient repeating a sentence, totaling five films. After a pilot study and sample calculation, the films were evaluated by 138 examiners: 46 orthodontists, 46 laypeople, and 46 prosthodontists. Each examiner evaluated the dentofacial esthetics of each film using visual analog scales. Data collected were statistically analyzed.Results:Highest scores were awarded to the film with no asymmetry between upper centrals and the one with 0.5 mm of asymmetry. The asymmetries of 1.5 mm and 2.0 mm had the lowest scores from all three groups.Conclusions:The results of this video analysis indicate that asymmetries equal to or greater than 1.0 mm between the upper central incisors edges jeopardize dentofacial esthetics.     

Does pulp cavity affect the center of resistance in three-dimensional tooth model? A finite element method study

Clinical Oral Investigations - To compare the center of resistance (Cres) of the maxillary central incisor in models with and without the pulp cavity and to evaluate the association of pulp...     

Does oral dryness influence pressure pain sensitivity in the oral mucosa of removable denture wearers?

Clinical Oral Investigations - This study aimed to determine if oral dryness is associated with oral pain sensitivity in removable denture wearers. The pressure pain threshold (PPT) in the mucosa...     

Anti-inflammatory mechanism of PPARγ on LPS-induced pulp cells: role of the ROS removal activity

ObjectivesPPARγ has an anti-inflammatory effect on LPS-induced pulpal inflammation by decreasing the expression of MMPs, ICAM-1 and VCAM-1. However, the anti-inflammatory mechanism of PPARγ on the cell adhesion molecules and their upper signal pathways has not been clarified in pulp cells. The aim of this study is to investigate the anti-inflammatory mechanism of PPARγ in pulpal inflammation.MethodsHuman dental pulp cells (HDPCs) were isolated from freshly extracted third molar and cultured. The over-expression of PPARγ was used by adenoviral PPARγ (Ad/PPARγ). The formation of ROS was analysed using DCFH-DA with FACS, and NO was analysed using colorimetric bioassay. The expression of inflammatory molecules and inflammatory mechanism of PPARγ involved signal pathway were determined by immunoblotting.ResultsLPS-induced HDPC decreased PPARγ expression gradually and strongly activated the ERK1/2 signals amongst the MAPK, and induced NF-κB translocation from the cytosol to the nucleus. On the other hand, the cells to restore PPARγ with Ad/PPARγ were inhibited ERK1/2 despite being stimulated with LPS. In addition, the cells treated with rosiglitazone (PPARγ agonist) also were inhibited ERK1/2 activation, and the expression of ICAM-1, VCAM-1 and NF-κB translocation under LPS stimulation. The GW9667 (PPARγ antagonist)-treated HDPC did not affect the adhesion molecules and signal activation. LPS-induced HDPC produced significant NO and ROS levels, but their production was attenuated in the PPARγ over-expressed cells. Overall, the PPARγ effect under LPS stimulation is due to the removal activity of cellular NO and ROS formation.ConclusionThese results suggest that anti-inflammatory mechanism of PPARγ is due to the removal activity of NO and ROS, and its removal effect suppressed ERK1/2 signal activation and NF-κB translocation. Therefore, the NO and ROS removal activity of PPARγ suggests major anti-inflammatory mechanism in HDPC, and it might offer us a possible molecule for various types of inflammatory inhibition.     

Does the nature of the definitive impression material influence the outcome of (mandibular) complete dentures?

The effects of impression materials on the outcome of complete dentures are poorly understood. This double-blind cross-over randomized controlled trial investigated eleven adult edentulous patients. Each received a maxillary denture and three mandibular dentures (which differed only in the three materials used to record the definitive impressions). The three mandibular dentures were given in a random order. Patients' opinions of each denture were recorded using a Linear Analogue Scale. There was a statistically-significant difference between the outcome of the dentures constructed when zinc-oxide eugenol was used, this material being least favoured (p < 0.001). It would therefore appear that care should be exercised when selecting impression materials when constructing mandibular complete dentures.     

Does the skin color of patients influence the treatment decision-making of dentists? A randomized questionnaire-based study

Clinical Oral Investigations - To investigate whether patients’ skin color could exert an influence on the dentist’s decision-making for treatment, in four different cities in Brazil....     

Tooth autotransplantation. What's the limit of our possibilities in conservative treatments?

Aim

When an extraction is necessary, it is possible to choose a donor tooth and transplant it into the site of the previous extraction. Aim of the present article is to present a series of cases of tooth autotransplantation to demonstrate how it is possible to preserve natural teeth and avoid or delay implant therapy.